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Sample records for caracteristiques mecaniques residuelles

  1. Mechanical behaviour of uranium; Comportement mecanique de l'uranium

    Energy Technology Data Exchange (ETDEWEB)

    Bernard, J L; Coureau, G [Commissariat a l' Energie Atomique, Dir. Industrielle, Saclay (France). Centre d' Etudes Nucleaires

    1957-07-01

    The chief mechanical properties of uranium, taken at room and at different temperatures, are presented in this report. (author) [French] Dans ce rapport sont presentees les principales caracteristiques mecaniques de l'uranium, relevees a l'ambiante et a differentes temperatures. (auteur)

  2. Caracteristiques epidemiologiques, cliniques et pronostiques de la ...

    African Journals Online (AJOL)

    Caracteristiques epidemiologiques, cliniques et pronostiques de la mortinaissance par cesarienne : etude de 97 cas colliges de Janvier 2008 a Decembre 2012 au chu Kara. Epidemiological, clinical and pronostical characteristics of stillbirth by cesarean se.

  3. Mechanics and electronics as auxiliary techniques in nuclear research and exploitation; Mecanique et electronique auxiliaires de la recherche et de l'exploitation nucleaire

    Energy Technology Data Exchange (ETDEWEB)

    Weill, J. [Commissariat a l' energie atomique et aux energies alternatives - CEA, Centre d' Etudes nucleaires de Saclay, Departement Electronique, Groupe Controle des Reacteurs (France)

    1959-07-01

    Electronics and mechanics form the basic techniques used in the field of measurement and control in nuclear physics experiments, and in nuclear machine installations. The delegate describes some instruments typical of the use of these techniques in the fields of calculation, detection, amplification and nuclear Installations. Reprint of a paper published in 'Bulletin S.F.M.' n. 25 (3. quarter 1957) [French] L'electronique et la mecanique constituent les techniques de base utilisees clans le domaine des mesures et du controle effectues dans les experiences de physique nucleaire et dans les installations des engins nucleaires. Le Conferencier decrit plusieurs appareils caracteristiques de l'emploi de ces techniques dans les domaines du calcul, des detecteurs, de l'amplification et des lnstallations nucleaires. Reproduction d'un article publie dans le 'Bulletin S.F.M.' n. 25 (3e trimestre 1957)

  4. Physical properties of beryllium oxide - Irradiation effects; Proprietes physiques et caracteristiques mecaniques de l'oxyde de beryllium fritte - Effet de l'irradiation et guerison

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    Elston, J; Caillat, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1958-07-01

    This work has been carried out in view of determining several physical properties of hot-pressed beryllium oxide under various conditions and the change of these properties after irradiation. Special attention has been paid on to the measurement of the thermal conductivity coefficient and thermal diffusivity coefficient. Several designs for the measurement of the thermal conductivity coefficient have been achieved. They permit its determination between 50 and 300 deg. C, between 400 and 800 deg. C. Some measurements have been made above 1000 deg. C. In order to measure the thermal diffusivity coefficient, we heat a perfectly flat surface of a sample in such a way that the heat flux is modulated (amplitude and frequency being adjustable). The thermal diffusivity coefficient is deduced from the variations of temperature observed on several spots. Tensile strength; compressive strength; expansion coefficient; sound velocity and crystal parameters have been also measured. Some of the measurements have been carried out after neutron irradiation. Some data have been obtained on the change of the properties of beryllium oxide depending on the integrated neutron flux. (author)Fren. [French] L'objet de cette etude est la determination de plusieurs proprietes physiques de l'oxyde de beryllium fritte sous charge dans differentes conditions et l'evolution de ces proprietes apres irradiation. Une attention particuliere a ete portee sur la mesure de la conductibilite et de la diffusivite thermiques. Differents montages ont ete realises pour mesurer la conductibilite thermique. Ils permettent la determination entre 50 et 300 deg. C, entre 400 et 800 deg. C; quelques mesures ont ete faites au-dessus de 1000 deg. C. Pour la mesure du coefficient de diffusivite thermique, on realise une attaque thermique, de frequence et d'amplitude reglables d'une face parfaitement plane d'un echantillon d'oxyde de beryllium. Les variations de temperature sont ovees en plusieurs points, on en deduit le coefficient de diffusivite thermique. Ont ete mesures egalement: la resistance a la traction; la resistance a la compression; le coefficient de dilatation; la vitesse de propagation du son; les parametres cristallins. Certaines des mesures ont ete effectuees apres irradiation par des neutrons. Quelques indications ont ete obtenues sur les variations des proprietes de l'oxyde de beryllium en fonction du flux integre recu. (auteur)

  5. Influence of rolling and annealing conditions on texture and mechanical properties of zirconium (1960); Influence des conditions de laminage et de recuit sur la texture et les proprietes mecaniques du zirconium (1960)

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    Orssaud, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1958-06-15

    Rolling and annealing textures of KROLL zirconium samples at several rolling rates were studied by pole figures with an automatic recorder versus the position in the sheet thickness. Tensile tests, hardness measurements and micrographic examinations allowed to study the evolution of the recrystallization and the variation of the mechanical properties after rolling and/or annealing. Annealing textures slightly varies with the annealing temperature. Annealing at 500 deg. C gives several peculiarities. This temperature seems characteristic in the study of zirconium. (author) [French] Les textures de laminage et de recuit d'echantillons de zirconium KROLL lamine a divers taux ont ete etudiees en tracant des diagrammes de figures de poles en divers points de l'epaisseur des toles, a l'aide d'un appareil a enregistrement automatique. Des essais de traction et des mesures de duretes ainsi que des micrographies ont permis de suivre l'evolution de la recristallisation et les variations des caracteristiques mecaniques au divers stades du laminage et du recuit. La texture de recuit parait varier avec la temperature utilisee. De nombreuses particularites qui apparaissent apres recuit vers 500 deg. C montrent l'importance de cette zone de temperature dans l'etude du zirconium. (auteur)

  6. Etude des phenomenes dynamiques ultrarapides et des caracteristiques impulsionnelles d'emission terahertz du supraconducteur YBCO

    Science.gov (United States)

    Savard, Stephane

    Les premieres etudes d'antennes a base de supraconducteurs a haute temperature critique emettant une impulsion electromagnetique dont le contenu en frequence se situe dans le domaine terahertz remontent a 1996. Une antenne supraconductrice est formee d'un micro-pont d'une couche mince supraconductrice sur lequel un courant continu est applique. Un faisceau laser dans le visible est focalise sur le micro-pont et place le supraconducteur dans un etat hors-equilibre ou des paires sont brisees. Grace a la relaxation des quasiparticules en surplus et eventuellement de la reformation des paires supraconductrices, nous pouvons etudier la nature de la supraconductivite. L'analyse de la cinetique temporelle du champ electromagnetique emis par une telle antenne terahertz supraconductrice s'est averee utile pour decrire qualitativement les caracteristiques de celle-ci en fonction des parametres d'operation tels que le courant applique, la temperature et la puissance d'excitation. La comprehension de l'etat hors-equilibre est la cle pour comprendre le fonctionnement des antennes terahertz supraconductrices a haute temperature critique. Dans le but de comprendre ultimement cet etat hors-equilibre, nous avions besoin d'une methode et d'un modele pour extraire de facon plus systematique les proprietes intrinseques du materiau qui compose l'antenne terahertz a partir des caracteristiques d'emission de celle-ci. Nous avons developpe une procedure pour calibrer le spectrometre dans le domaine temporel en utilisant des antennes terahertz de GaAs bombarde aux protons H+ comme emetteur et detecteur. Une fois le montage calibre, nous y avons insere une antenne emettrice dipolaire de YBa 2Cu3O7-delta . Un modele avec des fonctions exponentielles de montee et de descente du signal est utilise pour lisser le spectre du champ electromagnetique de l'antenne de YBa 2Cu3O7-delta, ce qui nous permet d'extraire les proprietes intrinseques de ce dernier. Pour confirmer la validite du modele

  7. Les superpolynomes symetriques dans les problemes a plusieurs corps de la mecanique quantique supersymetrique

    Science.gov (United States)

    Desrosiers, Patrick

    S'inspirant de la supersymetrie, on construit dans cette these une nouvelle generalisation de la theorie des fonctions symetriques. Une theorie physique est supersymetrique si: (1) elle contient des bosons (particules de spin entier) et des fermions (particules de spin demi-entier); (2) elle reste inchangee suite a une transformation des bosons en fermions et vice versa. Les fonctions symetriques dans le superespace (superfonctions symetriques) incorporent a la fois des variables commutatives (bosoniques) et anticommutatives (fermioniques). Ces dernieres engendrent une algebre de Grassmann. Une superfonction symetrique est invariante sous l'echange simultane des variables bosoniques et fermioniques (action diagonale du groupe symetrique); elle se caracterise par une superpartition, i.e., une juxtaposition appropriee de partitions usuelles d'entiers non negatifs. On utilise deux approches dans l'elaboration de la theorie des superfonctions symetriques: l'une provient de la combinatoire et l'autre, de la physique. Suivant la premiere approche, on obtient l'extension des elements standards de la theorie des fonctions symetriques fonctions monomiales, fonctions symetriques elementaires, fonctions completement symetriques, series de puissances, fonctions generatrices et formules de Cauchy. On demontre egalement qu'il existe une extension naturelle, a un parametre, du produit scalaire combinatoire defini par l'orthogonalite des series de puissances dans le superespace. La seconde approche consiste a resoudre des problemes a N corps de la mecanique quantique supersymetrique. On etudie les extensions supersymetriques des modeles Calogero-Moser-Sutherland (CMS), lesquels decrivent l'evolution de particules dont le potentiel d'inter action est proportionnel a l'inverse du carre de la distance separant les particules. Deux modeles supersymetriques CMS sont resolus: trigonometrique (sur un cercle) et rationnel (sur une ligne) avec confinement harmonique. Leurs fonctions d

  8. On the density of eigenvalues of a random matrix; Concernant la densite des racines caracteristiques d'une matrice stochastique

    Energy Technology Data Exchange (ETDEWEB)

    Mehta, M. L. [Institute of Fundamental Research Bombay (India); Gaudin, M. [Commissariat a l' energie atomique et aux energies alternatives - CEA, Centre d' Etudes Nucleaires de Saclay, Gif-sur-Yvette (France)

    1960-07-01

    An exact expression for the density of eigenvalues of a random- matrix is derived. When the order of the matrix becomes infinite, it can be seen very directly that it goes over to Wigner's 'semi-circle law'. Reprint of a paper published in 'Nuclear Physics' 18, 1960, p. 420-427 [French] On deduit une expression precise pour la densite des racines caracteristiques d'une matrice stochastique. Quand l'ordre de la matrice devient infini, on peut voir facilement qu'elle obeit a la loi dite 'semi-circulaire' de Wigner. Reproduction d'un article publie dans 'Nuclear Physics' 18, 1960, p. 420-427.

  9. Durability of cement-based materials: modeling of the influence of physical and chemical equilibria on the microstructure and the residual mechanical properties; Durabilite des materiaux cimentaires: modelisation de l'influence des equilibres physico-chimiques sur la microstructure et les proprietes mecaniques residuelles

    Energy Technology Data Exchange (ETDEWEB)

    Guillon, E

    2004-09-15

    A large part of mechanical and durability characteristics of cement-based materials comes from the performances of the hydrated cement, cohesive matrix surrounding the granular skeleton. Experimental studies, in situ or in laboratory, associated to models, have notably enhanced knowledge on the cement material and led to adapted formulations to specific applications or particularly aggressive environments. Nevertheless, these models, developed for precise cases, do not permit to specifically conclude for other experimental conclusions. To extend its applicability domain, we propose a new evolutive approach, based on reactive transport expressed at the microstructure scale of the cement. In a general point of view, the evolution of the solid compounds of the cement matrix, by dissolutions or precipitations, during chemical aggressions can be related to the pore solution evolution, and this one relied to the ionic exchanges with the external environment. By the utilization of a geochemical code associated to a thermodynamical database and coupled to a 3D transport model, this approach authorizes the study of all aggressive solution. The approach has been validated by the comparison of experimental observations to simulated degradations for three different environments (pure water, mineralized water, seawater) and on three different materials (CEM I Portland cement with 0.25, 0.4 and 0.5 water-to cement ratio). The microstructural approach permits also to have access to mechanical properties evolutions. During chemical aggressions, the cement matrix evolution is traduced in a microstructure evolution. This one is represented from 3D images similarly to the models developed at NIST (National Institute of Standards and Technology). A new finite-element model, validated on previous tests or models, evaluates the stiffness of the cement paste, using as a mesh these microstructures. Our approach identifies and quantifies the major influence of porosity and its spatial distribution on the Young modulus evolution of a chemically degraded cement paste. (author)

  10. Elaboration de nouvelles approches micromecaniques pour l'optimisation des performances mecaniques des materiaux heterogenes

    Science.gov (United States)

    Aboutajeddine, Ahmed

    donner de bons resultats. Finalement, ce modele de Mori-Tanaka corrige est utilise avec les operateurs de Hill pour construire un modele de transition d'echelle pour les materiaux ayant une interphase elastoplastique. La loi de comportement effective trouvee est de nature incrementale et elle est conjuguee a la relation de la plasticite de l'interphase. Des simulations d'essais mecaniques pour plusieurs proprietes de l'interphase plastique a permis de dresser des profils de l'enrobage octroyant un meilleur comportement au materiau.

  11. Electrical characteristics of sphere-plane type spark counters; Caracteristiques electriques de compteurs a etincelles du type sphere-plan; Ehlektricheskie kharakteristiki iskrovykh schetchikov tipa shar-ploskost'; Caracteristicas electricas de los contadores de chispas del tipo esfera-plano

    Energy Technology Data Exchange (ETDEWEB)

    Laborie, P; Blanc, D [Centre de Physique Nucleaire, Faculte des Sciences de Toulouse (France)

    1962-04-15

    The authors describe here the mechanical construction and operating characteristics of spark detectors using a small (0.30 mm) diameter sphere as anode, set opposite to a plane cathode and working by the ''corona'' effect, in air at atmospheric pressure. Counting characteristics are very similar to those of Rosenblum-type anode wire detectors. However, the sphere counter has a certain superiority over the Rosenblum counter inherent in its geometry : (a) there sidual current (background) is low and the release of ozone and nitrous oxides during the spark is not of great significance; (b) its self-capacity being very small, the detector gives a faster response; (c) unlike in the case of wire counters, efficiency is independent of particle incidence direction; (d) its sensitive volume, that of a solid of revolution around the axis of symmetry of the detector, amounts to a few cubic millimetres and, being very clearly defined, permits realization of accurate telescopic devices. (author) [French] Les auteurs decrivent la realisation mecanique et les caracteristiques de fonctionnement de detecteurs a etincelles utilisant comme anode une sphere de petit diametre (0,30 mm), disposee en regard d'une cathode plane, et fonctionnant en regime d'effet , dans l'air sous la pression atmospherique. Les caracteristiques de comptage sont voisines de celles des detecteurs a fil anodique, du type Rosenblum. Le compteur a sphere presente cependant sur le compteur de Rosenblum un certain nombre d'avantages lies a sa geometrie: a) le courant residuel (bruit de fond) est faible, et le degagement d'ozone et d'oxydes de l'azote lors des etincelles est peu considerable; b) sa capacite propre etant tres petite, le detecteur presente une reponse plus rapide; c) l'efficacite est independante de la direction d'incidence de la particule, contrairement a ce qui a lieu pour les compteurs a fil; d) le volume sensible de revolution autour de l'axe de symetrie du detecteur, qui est de

  12. Characteristics and construction problems of EL 4; Caracteristiques et problemes de construction d'EL4

    Energy Technology Data Exchange (ETDEWEB)

    Carle, R; Schulhof, P [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires; Sevin, Ph [Electricite de France (EDF), 75 - Paris (France); Buttin, J [Societe INDATOM (France)

    1964-07-01

    detail and the connections to be employed were tested. The whole circuit is made in fairly classical materials (slightly alloyed steels) whose behaviour in the carbon dioxyde at 500 deg. C was proved. The CO{sub 2}, and heavy water circuits construction will begin in October 1964. Aerodynamic tests were carried out for the helico-centrifugal blowers (of unit power 9 MW). The choice of a pressure as high as 60 kg/cm{sup 2} does not seem to induce new problems in connection with leaks on the machine shafts. Finally, the choice of a type of CO{sub 2} - steam heat exchanger with forced circulation led Electricite de France to test the operation and stability of a prototype exchanger in its test plant The reactor will be equipped with a de-pressurizing and de-superheating system which will allow the reactor to operate at 20 p. 100 of its nominal power whether the turbo-alternator is available or not. (authors) [French] EL 4 est le prototype d'une filiere originale de reacteurs moderes a l'eau lourde et refroidis au gaz carbonique. Son etude a ete menee dans la double optique de: - realiser un reacteur suffisamment important et complet pour y tester l'ensemble des problemes de construction et d'exploitation de la filiere; - menager dans l'installation les possibilites de tenir compte des ameliorations (materiaux nouveaux, elements combustibles ameliores) qui sont etudiees par ailleurs. Le premier objectif n'etait envisageable que sous reserve d'un volume d'etudes preliminaires important. A ce titre, ont ete realises et essayes de 1962 a 1964 plusieurs canaux prototypes, hors pile, mais dans les conditions reelles de temperature et de pression. Ces essais ont montre la bonne tenue des materiaux aux difficiles conditions mecaniques et chimiques du projet. Ces installations seront d'ailleurs disponibles pour eprouver, avant mise en pile, les modifications ulterieures. D'importants essais touchant la securite du reacteur en cas d'explosion du circuit de CO{sub 2}, ont ete realises

  13. Physico-chemical characteristics of uraniferous supergene minerals (1960); Caracteristiques physico-chimiques des mineraux uraniferes supergenes (1960)

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    Semat, M A [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    Transport and deposit conditions of uraniferous minerals are briefly described. The synthesis of crystallographic, physical, optical and thermal properties allows to define the main characteristics of this mineralogical group. Tables have been arranged in order to make easy the identification of the supergene U minerals: - investigation by anion and cation; - system, cleavages, cell parameters, interplanar spacings, refractive indices, optical bearings; - classification by decreasing values of the most intense line of the powder diagram; - by anion, diagram for the 3 higher interplanar spacings; - by anion, diagram of the refractive indices. (author) [French] Les conditions de transport et de depot des mineraux uraniferes sont brievement exposees. La synthese des proprietes cristallographiques, physiques, optiques et thermiques permet de definir les caracteristiques essentielles de ce groupe mineralogique. Les tableaux suivants ont ete etablis pour faciliter l'identification des mineraux uraniferes supergenes: - recherche par anion et cation; - systeme, clivages, parametres, distances reticulaires, indices et refraction, orientation optique; - classement par valeurs decroissantes de la raie la plus intense du diagramme de poudre; - diagramme, etabli par anion, selon les 3 distances reticulaires les plus elevees; - diagramme, etabli par anion, d'indices de refraction. (auteur)

  14. The multi-sphere technique. 1 - general characteristics and applications; La technique multisphere. 1 - caracteristiques generales et applications

    Energy Technology Data Exchange (ETDEWEB)

    Zaborcwski, H [Commissariat a l' Energie Atomique, Cadarache (France). Centre d' Etudes Nucleaires

    1965-07-01

    A study is made of the general characteristics and the applications of the multisphere technique for flux measurements, dosimetry and the spectrometry of neutron sources ranging from thermal, up to 7 MeV neutrons. We give the equations relating to three fluxmeters (proportional long counters) for the measurements of the flux. Other equations have been derived : 1 - for multi-collision rad and rem dosimetry and first collision rad dosimetry; 2 - for the spectrometry and dosimetry of neutrons in five energy bands using a method similar to that used by threshold detectors. (author) [French] Nous etudions les caracteristiques generales et les applications de la technique multisphere pour les mesures de flux, la dosimetrie et la spectrometrie des sources de neutrons depuis les thermiques jusqu'a 7 MeV. Nous donnons les equations relatives a trois fluxmetres (longs compteurs equivalents) pour les mesures en flux. D'autres equations ont ete derivees: 1 - pour la dosimetrie en rad et en rem de multicollision et en rad de premiere collision; 2 - pour la spectrometrie et la dosimetrie des neutrons en cinq bandes energetiques suivant une methode voisine de celle utilisee par detecteurs a seuil. (auteur)

  15. Characteristics of breathing apparatus used in health physics; Caracteristiques de l'appareil respiratoire utilisables en radioprotection

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    Perissin-Pirasset, F. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1967-07-01

    The present state of knowledge makes it possible to envisage the calculation of doses absorbed by various parts of the respiration apparatus following inhalation of radio-active dusts contained in aerosols. After recalling some anatomical and histological considerations, the author presents various curves showing the deposition of dusts in the three parts of the breathing apparatus: - the rhino-pharynx - the trachea and wind-pipe - the pulmonary parenchyma. The dusts can be classified in three groups of biological solubility according to which the rates of elimination of the particles from the organs are different. A synthesis of these data is given in elimination diagrams. In order to calculate the doses it is necessary furthermore to know certain anatomical and physiological characteristics of a standard man. (author) [French] L'etat actuel des connaissances permet d'envisager le calcul des doses recues par les differentes parties de l'arbre respiratoire, a la suite d'inhalation de poussieres radioactives contenues dans des aerosols. Apres un rappel de notions anatomiques et histologiques, nous presentons differentes courbes de depot des poussieres dans les trois etages respiratoires: - le rhino-pharynx - la trachee et les bronches - le parenchyme pulmonaire. Les poussieres peuvent etre classees en trois groupes de solubilite biologique selon lesquels les vitesses d'elimination des particules a partir des organes sont differentes. Ceci peut etre synthetise dans des schemas d'elimination. Pour permettre le calcul des doses, il faut en outre disposer des caracteristiques d'un homme standard, du point de vue anatomique et physiologique. (auteur)

  16. Characteristics of breathing apparatus used in health physics; Caracteristiques de l'appareil respiratoire utilisables en radioprotection

    Energy Technology Data Exchange (ETDEWEB)

    Perissin-Pirasset, F [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1967-07-01

    The present state of knowledge makes it possible to envisage the calculation of doses absorbed by various parts of the respiration apparatus following inhalation of radio-active dusts contained in aerosols. After recalling some anatomical and histological considerations, the author presents various curves showing the deposition of dusts in the three parts of the breathing apparatus: - the rhino-pharynx - the trachea and wind-pipe - the pulmonary parenchyma. The dusts can be classified in three groups of biological solubility according to which the rates of elimination of the particles from the organs are different. A synthesis of these data is given in elimination diagrams. In order to calculate the doses it is necessary furthermore to know certain anatomical and physiological characteristics of a standard man. (author) [French] L'etat actuel des connaissances permet d'envisager le calcul des doses recues par les differentes parties de l'arbre respiratoire, a la suite d'inhalation de poussieres radioactives contenues dans des aerosols. Apres un rappel de notions anatomiques et histologiques, nous presentons differentes courbes de depot des poussieres dans les trois etages respiratoires: - le rhino-pharynx - la trachee et les bronches - le parenchyme pulmonaire. Les poussieres peuvent etre classees en trois groupes de solubilite biologique selon lesquels les vitesses d'elimination des particules a partir des organes sont differentes. Ceci peut etre synthetise dans des schemas d'elimination. Pour permettre le calcul des doses, il faut en outre disposer des caracteristiques d'un homme standard, du point de vue anatomique et physiologique. (auteur)

  17. Porosity determination of damaged fault zones and role of rock state on fluid flow during fluid rock interactions. Mineralogy, porosity structures and mechanical properties; Determination de la porosite des zones endommagees autour des failles et role de l'etat du materiau sur les proprietes d'echange fluides-roches: Mineralogie, structures de porosite, caracteristiques mecaniques

    Energy Technology Data Exchange (ETDEWEB)

    Surma, F.

    2003-07-01

    Fault zone structure is characterized by a fault core (gouge, cataclasite, mylonite), a damage zone (small faults, fractures, veins fold) and a proto-lith. We can clearly describe these structures in the Soultz-sous-Forets granite (HDR Project, France) and in the Nojima Fault zone (Kobe, Japan). This work shows us that the structures are the same ones in the two sites in spite of their different deformation mode one in extension and the other in compression. We propose, starting from the petrographic observations, a study of porosity and physical properties, a fluid flow model in a altered and fractured granite, taking into account the evolution of the fluid pressure and the processes of dissolution-precipitation during an earthquake. In the case of extension, the inter-seismic period is associated to an opening of the fractures in the fault damaged zone and an increase in porosity due to the rock alteration. During the earthquake, the fractures are closed and the fluid is expelled. In the case of compression, the inter-seismic period is associated to the closing of the fractures in the matrix and the expulsion of the fluids towards the fault whereas curing the earthquake the fractures open because of the fluid pressure increase. Thus, there is a constant competition between the processes which enhance permeability and those which tend to reduce it. These processes (stresses, mineral precipitation, fluid pressure variation... etc) are the same ones in the various contexts, but they do not interfere at the same time during an earthquake. (author)

  18. Tables of formulae for calculating the mechanics of stacks in gas-graphite reactors; Formulaire pour le calcul de la mecanique des empilements des reacteurs graphite-gaz

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1968-07-01

    This collection of formulae only gives, for nuclear graphite stacks. The mechanical effects due to the strains, thermal or not, of steel structures supporting or surrounding graphite blocks. Equations have been established by mean of experiments made at Chinon with large pile models. Thus, it is possible to calculate displacement, strain and stress in the EDF type stacks of horizontal triangular block lattice. (authors) [French] Le domaine de ce formulaire est strictement limite aux effets mecaniques, pour les empilements, des deformations, thermiques ou autres, des structures metalliques de soutien (aire - support et corset). On propose un ensemble de relations qui ont ete etablies a la suite des essais de CHINON sur des maquettes de grande taille. Ces relations permettent le calcul des mouvements, des deformations et des contraintes dans les empilements du type EDF, a reseau horizontal triangulaire regulier. (auteurs)

  19. Intermediate energy neutron fast chopper associated to the pile EL3; Spectrometre mecanique rapide pour neutrons intermediaires associe a la pile EL3

    Energy Technology Data Exchange (ETDEWEB)

    Julien, J; Netter, F; Martin, R; Rouge, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Arditti, R; Chaffiotte, P [S.E.M. Hispano-Suisa (France)

    1958-07-01

    The apparatus is a fast chopper placed on a beam issued from the tank of the pile EL3. It is composed of a steel rotor with a rigid vertical axis and eight pairs of slits in the maximum cross-section plane (diameter 48 cm). The originality of the apparatus consists mainly in the driving system by oil turbine, whiclows a more reliable and versatile operation. The spectrometer is running regularly at 15000 r.p.m. In the conditions, the slits (precision of cutting: {+-} 5 microns) release neutron beams with time half-width equal to 1/4 micro-second. Therefore, with a 20 meter flight-path, the resolution power of the fast chopper is about 10 milli-microsecond/metre. All the safety devices are provided to ensure a steady running, without permanent control. The speed of rotation is stabilized to better than {+-} 1/1000 in all the rate range between 6 000 and 15 500 r.p.m. A lead device for moving in and out the sample allows to work with radioactive samples. The apparatus is connected to a hundred 1/4 microsecond channel time-of-flight selector. A thousand channel selector with magnetic memory (Argonne type) will be ready in a few months. (author)Fren. [French] L'appareil est un spectrometre mecanique rapide dispose sur un des faisceaux sortant de la cuve de la pile EL3. Il comprend un rotor d'acier a axe vertical rigide avec huit paires de fentes disposees dans le plan de section maximum (diametre 40 cm). L'originalite de l'appareil tient surtout dans le systeme d'entrainement par turbine a huile, qui assure une grande securite et une grande souplesse de fonctionnement. Le spectrometre tourne a 15000 tours/mn de fa n reguliere. Dans ces conditions, les fentes (executees a {+-} 5 microns pres liberent des faisceaux de neutrons avec une largeur a mi-hauteur en temps de 1/4 de microseconde. Avec une base de parcours de 20 m, le pouvoir de resolution du spectrometre mecanique est donc voisin de 10 millimicroseconde/metre. Tous les dispositifs de securite sont prevus pour

  20. Characteristics of membranes which are suitable for isotopic separation by gaseous diffusion; Caracteristiques des barrieres utilisables pour la separation isotopique par diffusion gazeuse

    Energy Technology Data Exchange (ETDEWEB)

    Massignon, D [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1958-07-01

    rayon de pore r{sub wicke} effectif en regime intermediaire, le rayon de pore r{sub sep.} effectif en separation et les repartitions de rayons de pore definies par la porosimetrie au mercure, le B.E.T. et la diffusion centrale des rayons X. Nous donnerons d'abord la definition adoptee en pratique pour ces grandeurs empiriques, adaptees a un controle rapide des qualites des barrieres, en les reliant aux proprietes caracteristiques de quelques modeles de structure poreuse. Dans une seconde partie, nous montrerons sur quelques exemples empruntes aux mesures de routine, comment elles permettent, par recoupement, d'ecarter les barrieres a structure defavorable. (auteur)

  1. Determination experimentale des principales caracteristiques ...

    African Journals Online (AJOL)

    Through the present research work, usual scientific parameters and characteristics of Borassus palm wood from Benin, are determined. Specifically, infradensity, shrinkage coefficient and behaviour, breaking stress in the direction of the fibbers at pulling, compression and bending, are known as well as Young modulus at ...

  2. The use of probe characteristics in plasma in the presence of a magnetic field (1960); Utilisation des caracteristiques de sondes dans des plasmas en presence de champ magnetique (1960)

    Energy Technology Data Exchange (ETDEWEB)

    Brunet, A; Geller, R; Leroy, J [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    In this article we recall the principal methods of interpretation of probe characteristics in plasma in the presence of magnetic fields. Our purpose is to resume and to present the methods in such a form as to be immediately applicable in a particular case. This article is therefore principally useful to experimenters. Finally we expose our practical view points by comparing of experimental methods. (author) [French] Dans cet article, nous rappelons les principales methodes d'interpretation des caracteristiques de sonde dans des plasmas en presence de champs magnetiques. Notre but est de resumer et de presenter sous forme inmediatement applicable ces methodes. Cet article est donc destine aux experimentateurs. Enfin, nous developpons nos etudes pratiques sur la question en etablissant des comparaisons experimentales entre les methodes. (auteur)

  3. Improvement of spectrographic analyses by the use of a mechanical packer in the arc distillation technique; Amelioration de l'analyse spectrograpique par l'utilisation d'un tasseur mecanique dans la methode de distillation dans l'arc

    Energy Technology Data Exchange (ETDEWEB)

    Buffereau, M; Deniaud, S; Pichotin, B; Violet, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-07-01

    One studies improvement of spectrographic analysis by the 'carrier distillation' method with the help of a mechanical device. Experiments and advantages of such an apparatus are given (precision and reproducibility improvement, operator factor suppression). A routine apparatus (French patent no 976.493) is described. (authors) [French] On etudie l'amelioration des analyses spectrographiques par la methode de distillation avec entra eur dans l'arc au moyen d'un tasseur mecanique. On indique les experiences realisees et les avantages de l'emploi d'un tel appareil (amelioration de la precision et de la reproductibilite, suppression du facteur operateur). On decrit l'appareil de routine objet du brevet no 976.493 du 29 mai 1964. (auteurs)

  4. TiNi shape memory alloys: effects of the fabrication route, the oxygen content and the zirconium or hafnium additions on the metallurgical characteristics and the thermomechanical properties; Alliages a memoires de forme de base TiNi: influence du mode de fabrication de la teneur en oxygene et de l`ajout de Zr ou Hf sur les caracteristiques metallurgiques et les proprietes mecaniques

    Energy Technology Data Exchange (ETDEWEB)

    Olier, P.

    1996-12-31

    In order to promote the development of Ti-Ni shape memory alloys, we have studied the correlation between the fabrication route, the chemical composition (O{sub 2} content, Zr or Hf additions), the metallurgical characteristics and the thermomechanical properties. A conventional sintering does not allow to obtain a homogeneous compound of pure Ti{sub 50}Ni{sub 50} alloy because of the occurrence of Kirkendall porosities which act as a diffusion barrier. An original process including combustion synthesis and hot-extrusion was successfully developed. Resulting products exhibit a smaller grain size (15-20{mu}m) and an enhanced workability in comparison with products obtained by arc-melting and subsequent hot rolling. The presence of oxygen in equiatomic Ti-Ni alloy induces the oxide precipitation of Ti{sub 4}Ni{sub 2}O{sub x} type (with x {<=} 1). The precipitated particle fraction is proportional to the oxygen nominal content of the alloy. We show that the decrease of the transformation temperatures is correlated with the decrease of Ti in solid solution due to Ti{sub 4}Ni{sub 2}O precipitation. Moreover, we find that a fine and homogenous oxide dispersion is suitable to decrease the grain size during hot rolling and to enhance to the one way shape memory properties. An increase of the typical transformation temperatures is obtained through of Zr or Hf (in substitution to Ti). But, an increase of the hardness is measured, and consequently the workability of the ternary alloys becomes reduced. However, it is worthwhile to point out that a Ti{sub 38}Ni{sub 50}Hf{sub 12} product obtained by arc melting and hot extrusion is able to fully recover an apparent plastic strain of more than 4% during tensile tests performed under special loading conditions. Such as behaviour is of great interest with respect to potential applications in a temperature range higher that 100 deg. C. (author). 105 refs.

  5. Study of portable particle accelerators used as neutron sources. Report 7-9. Characteristics of accelerators currently available on the market; Etude sur les accelerateurs de particules du type transportable utilises en tant que sources de neutrons. Rapport 7-9. Caracteristiques des accelerateurs actuellement sur le marche

    Energy Technology Data Exchange (ETDEWEB)

    Godar, Serge [Communaute europeenne de l' energie atomique - Euratom, Brussels (Belgium)

    1964-08-15

    This report indicates characteristics of available accelerators adapted to neutron production. Indicated information are for example: brand and type, brief description, maximum high voltage, ion source, ion current, gas introduction system, titanium self-target, beam focusing system, target diameter, reaction used for neutron production, target cooling, generator use temperature, dimensions, weight, manufacturer address, and so on [French] L'ensemble de cette etude bibliographique est traitee dans une serie de huit rapports, chacun ayant trait a un aspect ou un domaine particulier. Ce rapport (No. 7-9) a pour but de donner des renseignements generaux aux chercheurs desirant acquerir un accelerateur de particules adapte a la production de neutrons. Les recherches concernant les caracteristiques des appareils actuellement sur le marche ont ete arretees a la date du 15 octobre 1963. Il n'est malheureusement pas possible de garantir toutes les caracteristiques fournies, etant donne les modifications continuelles apportees a ces generateurs.

  6. The main characteristics of the Saclay proton synchrotron, and the results obtained at the time of its setting in operation; Les caracteristiques principales du synchrotron a protons de Saclay et les resultats obtenus lors de la mise en route

    Energy Technology Data Exchange (ETDEWEB)

    Bruck, H; Debraine, P; Levy-Mandel, R; Lutz, J; Maillet, R; Podliasky, I; Prevot, F; Taieb, J; Winter, S D [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1958-07-01

    This paper consists on the one hand of a brief outline of the chief advantages of some characteristics peculiar to Saturne, particularly: the separation of the pole pieces from the body of the magnet, the structure of the vacuum chamber, the system of electrostatic deflectors of the injection optics and the HF cavity; and on the other hand of the difficulties encountered since starting up to improve the number of particles supplied by an induction electrode. The results obtained are also given, as for example the photographs taken in the propane chamber. (author)Fren. [French] La presente communication comporte d'une part un bref apercu des principaux avantages de quelques caracteristiques propres a Saturne et en particulier: la separation des pieces polaires de la masse de l'aimant, la structure de la chambre a vide, le systeme de deflecteurs electrostatiques de l'optique d'injection et la cavite HF; d'autre part, les difficultes rencontrees depuis la mise en route pour ameliorer le nombre de particules donne par une electrode d'induction, ainsi que les resultats obtenus comme par exemple les photographies prises dans la chambre a propane. (auteur)

  7. Application of general methods for the study of porous materials to the determination of the characteristics of barriers; Application des methodes generales d'etudes des corps poreux a la determination des caracteristiques des barrieres

    Energy Technology Data Exchange (ETDEWEB)

    Plurien, P; Charpin, J; Mommejac, S [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1958-07-01

    Barriers foreseen for the separation of uranium isotopes by gaseous diffusion must posses pores of about 100 Angstrom radius and as high an output as possible. They should thus be of small but uniform thickness. In view of these conditions it is necessary to adapt the normal methods available for studying porous materials in order to check the characteristics of the prototypes examined. It has been found that only by cross-comparison of data from various methods can progress in the development of different prototypes be followed. The following account consists of two parts: 1) A review of the main experimental methods we have used: a) various absorption methods, b) electron microscopy, c) X-ray studies, d) mercury porosimetry, e) liquid permeability, f) gas permeability, g) measurement of separation efficiency. 2) Comparison of the results obtained using these various methods and their application with a view to acquiring as complete a knowledge as possible of the structure of the barrier. (author) [French] Les barrieres susceptibles d'etre utilisees pour la separation des isotopes de l'uranium, par diffusion gazeuse, doivent presenter des pores de rayon de l'ordre de 100 Angstrom et un debit aussi grand que possible. Elles doivent donc avoir une epaisseur faible et constante. Ces conditions necessitent une adaptation des methodes usuelles d'etude des corps poreux pour controler les caracteristiques des prototypes etudies. Il est apparu que seul le recoupement entre diverses methodes permet de suivre les progres dans la realisation de differents prototypes. L'expose qui va suivre comprend deux parties: 1) Une revue des principales methodes experimentales que nous utilisons: a) differentes methodes d'absorption, b) microscopie electronique, c) rayons X, d) porosimetrie a mercure, e) permeabilite aux liquides, f) permeabilite aux gaz, g) mesure de l'efficacite de separation. 2) Comparaison des differents resultats obtenus par ces diverses methodes et leur application

  8. Contribution to the micro-calorimetric study of the characteristics of radio-elements and to their qualitative and quantitative analysis; Contribution a l'etude microcalorimetrique des caracteristiques des radio-elements et a leurs analyses qualitative et quantitative

    Energy Technology Data Exchange (ETDEWEB)

    Ozias, Y [Centre de Production de Plutonium de Marcoule, 30 (France)

    1964-10-01

    equal to that obtained by mass spectrography (destruction of the sample) 1 to 3 per cent, and higher than that obtained by counting techniques (greater than 5 per cent). (author) [French] Le principe de cette etude consiste a enregistrer avec le microcalorimetre E. CALVET le flux d'energie emis par les radioelements en fonction du temps at a partir de cette courbe de determiner soit leurs caracteristiques (periode et energie du rayonnement), soit la composition d'un melange de radioelements. Dans une premiere partie on a adapte les relations theoriques de la radioactivite a l'etude microcalorimetrique. Dans une deuxieme partie on determine experimentalement au microcalorimetre E. CALVET les caracteristiques de divers radioelements, yttrium 90, phosphore 32, soufre 35, iode 131, etc. et leurs melanges. On a etudie plus particulierement l'analyse isotopique du melange de {sup 239}Pu, de {sup 240}Pu et eventuellement de {sup 241}Pu. La methode microcalorimetrique n'a pas la sensibilite des methodes classiques de comptage, sa limite actuelle para etre de l'ordre du micro-watt pour les appareils utilises, mais elle est la plus directe pour les emetteurs de rayonnements facilement absorbables({alpha} et {beta}). Pour les emetteurs {gamma} une partie seulement de l'energie est absorbee par les parois du recipient. La determination de leurs caracteristiques et de leurs masses dans les melanges ne depend ni de la forme, ni de la dilution, ni surtout de l'auto-absorption de la source. Pour des echantillons de forte activite, cette auto-absorption est pour les methodes classiques la source de grosses difficultes entra ant de multiples manipulations: divisions, mise en solution, dilutions qui introduisent autant de causes d'erreur. La methode calorimetrique permet de travailler sur l'echantillon brut. Toutes les mesures ont ete faites avec le microcalorimetre E. CALVET classique; mais pour effectuer une mesure tres precise de' l'energie due au rayonnement {gamma} il faut faire

  9. Mechanical time-shutter for spectrograph with exposure times from 1.5 {mu}s to 3 ms; Un obturateur mecanique pour spectrographe dont le temps d'exposition varie de 1,5 microseconde a 3 millisecondes

    Energy Technology Data Exchange (ETDEWEB)

    Becker, L; Drawin, H W [Commissariat a l' Energie Atomique, Association Euratom - CEA, Groupe de Recherches sur la Fusion Controlee, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1965-07-01

    A mechanical time-shutter for exposure-times ranging from l,5 {mu}s to 3 ms is described. The apparatus is designed for spectrographic observations of pulsed electrical discharges which show rapidly varying spectral emissivities. For the mechanical part of the shutter we used a specially formed fast rotating disk having a slit. Triggering of the discharge is achieved by the rotating disk - in connection with photocells. Both the instant at which - after the beginning of the electrical discharge - the exposure shall begin, and the duration of exposure which will then follow can be 'preselected' on a special electronic control device. All functions: rotation of the disk - ignition of the discharge - exposure - switch-off of the disk are controlled electronically. The principle and the main electronic control parts of this versatile instrument are described. (authors) [French] On decrit un obturateur spectrographique rapide ayant des temps d'exposition allant de 1,5 {mu}s a 3 ms. L'obturateur est concu pour faire des observations spectrographiques de decharges pulsees dont l'emission spectrale varie rapidement. En ce qui concerne la partie mecanique nous avons utilise un disque comprenant une fente, qui tourne devant la fente d'entree du spectrographe. L'amorcage de la decharge est assure par le disque lui-meme, a l'aide de cellules photoelectriques. L'instant a partir duquel l'observation doit commencer - apres avoir amorce la decharge -, ainsi que la duree d'exposition qui suit, peuvent etre preselectionnes sur un tiroir electronique. Toutes les fonctions: mise en rotation du disque - amorcage de la decharge - exposition - freinage du disque se suivent automatiquement. Le principe ainsi que les circuits electroniques de controle de cet appareil sont decrits. (auteur)

  10. Cellular properties of slug flow in vertical co-current gas-liquid flow: slug-churn transition; Caracteristiques cellulaires du regime a poches en ecoulement gaz-liquide co-courant vertical. Transition vers le regime destructure

    Energy Technology Data Exchange (ETDEWEB)

    Lusseyran, Francois

    1990-12-13

    This research thesis reports the study and description of the structure of a slug flow regime in a co-current vertical cylindrical duct, and the characterization and prediction of its transition towards a slug-churn (de-structured) regime. Flow physical mechanisms highlighted by the measurement of two important dynamics variables (wall friction and thickness of liquid films) are related to hypotheses of cellular models. The author first proposes an overview of slug flow regimes: theoretical steady and one-dimensional analysis, mass assessment equations of cellular models, application to the assessment of the flow rate and of the thickness of the film surrounding the gas slug. In the second part, the author addresses the slug flow regime transition towards the slug-churn regime: assessment of the evolution of flow dynamic properties, use of average wall friction analysis to obtain a relevant transition criterion. The third part presents experimental conditions, and measurement methods: conductometry for thickness measurement, polarography for wall friction measurement, and gas phase detection by using an optic barrier or optic fibres [French] Les ecoulements gaz-liquide en conduite verticale presentent quatre configurations ou regimes d'ecoulement. Ce travail porte sur le regime a poches et sur la transition vers la configuration qui lui succede: le regime destructure (churn flow). Les mesures sont effectuees a 200D du point d'injection du gaz, dans une conduite de 12.2 mm de diametre et pour le couple de fluides eau-azote. Les deux principales grandeurs mesurees en fonction des flux d'entree sont: le frottement parietal instantane (methode electrochimique) et l'epaisseur de film instantanee (methode conductimetrique). Une detection optique simultanee de la presence des phases permet un traitement conditionnel de la base de donnees. Les caracteristiques de la cellule moyenne representative de chaque point de fonctionnement en sont deduites: longueur de la cellule

  11. caracteristiques hydrochimiques et microbiologiques des eaux

    African Journals Online (AJOL)

    AISA

    composés azotés minéraux (NO2. -, NO3. -, NH4. +) ont été dosés à l'aide d'un autoanalyseur. Technicon AA2 selon les modalités préconisées par (Strickland et Parsons (1972)). ANALYSES BACTERIOLOGIQUES. Le dénombrement des coliformes a été effectué après une incubation à 44° C durant 24 h sur milieu gélosé ...

  12. Caracteristiques Sociodemographiques Du Begaiement En Milieu ...

    African Journals Online (AJOL)

    Introduction: The objective of this study was to look for the prevalence of stuttering and describe the epidemiological profile of the stutterer in school environment in Lome in Togo. Material and methods: our work was to frame 5 official public primary schools of the capital including the municipality of Lome 2 and 3 in the ...

  13. Relativistic quantum mechanics; Mecanique quantique relativiste

    Energy Technology Data Exchange (ETDEWEB)

    Ollitrault, J.Y. [CEA Saclay, 91 - Gif-sur-Yvette (France). Service de Physique Theorique]|[Universite Pierre et Marie Curie, 75 - Paris (France)

    1998-12-01

    These notes form an introduction to relativistic quantum mechanics. The mathematical formalism has been reduced to the minimum in order to enable the reader to calculate elementary physical processes. The second quantification and the field theory are the logical followings of this course. The reader is expected to know analytical mechanics (Lagrangian and Hamiltonian), non-relativistic quantum mechanics and some basis of restricted relativity. The purpose of the first 3 chapters is to define the quantum mechanics framework for already known notions about rotation transformations, wave propagation and restricted theory of relativity. The next 3 chapters are devoted to the application of relativistic quantum mechanics to a particle with 0,1/5 and 1 spin value. The last chapter deals with the processes involving several particles, these processes require field theory framework to be thoroughly described. (A.C.) 2 refs.

  14. EVOLUTION D'UN PROBLEME DE MECANIQUE :

    OpenAIRE

    YAVUZ, Ahmet

    2008-01-01

    Ce travail a pour objectif de mettre en évidence l'évolution du rapport à la résolution de problèmes en mécanique à travers l'étude du dispositif de la machine d'Atwood dans les manuels parus entre XVIIIe et XIXe siècle. L'étude de cette évolution permet de mieux comprendre certaines habitudes des enseignants et des étudiants lors de la résolution de problème, ainsi que de répondre à la question pourquoi la résolution de problème est une activité importante en physique. D'abord, les développe...

  15. A study of filtering problems of background noise in nuclear spectrometry, improvement of signal-to-noise ratio, and of pulse characteristics produced by the optimum predictor device; Etude de problemes de filtrage de bruit de fond en spectrometrie nucleaire, amelioration du rapport signal sur bruit et des caracteristiques de l'impulsion mise en forme par le dispositif du predicteur optimum

    Energy Technology Data Exchange (ETDEWEB)

    Benda, J [Commissariat a l' Energie Atomique, 91 - Saclay (France). Centre d' Etudes Nucleaires

    1967-05-01

    The purpose of nuclear spectrometry is the precise measurement of particles energy. The resolving power of a spectrometer design is an important factor. Two main phenomena are involved in the limitation of this resolving power: The statistical fluctuations of the detector itself, and the background noise. For a given noise, the theory of filters enables the calculation of networks specially designed for the improvement of signal to noise ratio. The proposed system should lead to an improvement of 10.5 per cent of this ratio. Experiments have confirmed this theoretical estimation. The predictor device also makes possible the obtaining of shortened pulses. (author) [French] Les mesures en spectrometrie nucleaire ont pour but la determination precise de l'energie des particules. Le pouvoir de resolution d'une chaine de spectrometrie est une caracteristique importante. Deux phenomenes principaux concourent a limiter ce pouvoir de resolution: les fluctuations statistiques du detecteur et le bruit de fond. Pour un bruit de fond donne, la theorie des filtres permet de calculer des reseaux susceptibles de modifier le rapport signal sur bruit. Le systeme propose permet d'ameliorer de 10.5 pour cent ce rapport lorsqu'on se place dans les conditions optimales. Les resultats experimentaux confirment les previsions. Le dispositif predicteur permet aussi un raccourcissement de l'impulsion dans le temps. (auteur)

  16. Elaboration d'une structure de collecte des matieres residuelles selon la Theorie Constructale

    Science.gov (United States)

    Al-Maalouf, George

    Currently, more than 80% of the waste management costs are attributed to the waste collection phase. In order to reduce these costs, one current solution resides in the implementation of waste transfer stations. In these stations, at least 3 collection vehicles transfer their load into a larger hauling truck. This cost reduction is based on the principle of economy of scale applied to the transportation sector. This solution improves the efficiency of the system; nevertheless, it does not optimize it. Recent studies show that the compactor trucks used in the collection phase generate significant economic losses mainly due to the frequent stops and the transportation to transfer stations often far from the collection area. This study suggests the restructuring of the waste collection process by dividing it into two phases: the collection phase, and the transportation to the transfer station phase. To achieve this, a deterministic theory called: "the Constructal Theory" (CT) is used. The results show that starting a certain density threshold, the application of the CT minimizes energy losses in the system. In fact, the collection is optimal if it is done using a combination of low capacity vehicle to collect door to door and transfer their charge into high-capacity trucks. These trucks will then transport their load to the transfer station. To minimize the costs of labor, this study proposes the use of Cybernetic Transport System (CTS) as an automated collection vehicle to collect small amounts of waste. Finally, the optimization method proposed is part of a decentralized approach to the collection and treatment of waste. This allows the implementation of multi-process waste treatment facilities on a territory scale. Keywords: Waste collection, Constructal Theory, Cybernetic Transportation Systems.

  17. Methodologie experimentale pour evaluer les caracteristiques des plateformes graphiques avioniques

    Science.gov (United States)

    Legault, Vincent

    Within a context where the aviation industry intensifies the development of new visually appealing features and where time-to-market must be as short as possible, rapid graphics processing benchmarking in a certified avionics environment becomes an important issue. With this work we intend to demonstrate that it is possible to deploy a high-performance graphics application on an avionics platform that uses certified graphical COTS components. Moreover, we would like to bring to the avionics community a methodology which will allow developers to identify the needed elements for graphics system optimisation and provide them tools that can measure the complexity of this type of application and measure the amount of resources to properly scale a graphics system according to their needs. As far as we know, no graphics performance profiling tool dedicated to critical embedded architectures has been proposed. We thus had the idea of implementing a specialized benchmarking tool that would be an appropriate and effective solution to this problem. Our solution resides in the extraction of the key graphics specifications from an inherited application to use them afterwards in a 3D image generation application.

  18. Caracteristiques des malnutris aigus severes decedes en milieu ...

    African Journals Online (AJOL)

    Mots clés: audit, enfant, malnutrition, mortalité, Côte d'Ivoire. English Title: Characteristics of people suffering from acute and severe malnutrition, deceased in a hospital environment in Abidjan (Republic of Cote d'Ivoire). English Abstract. Introduction: The infant and juvenile mortality linked to acute malnutrition remains high ...

  19. 75 caracteristiques et evolution des operations de fusions

    African Journals Online (AJOL)

    Elles apparaissent enfin comme un moyen à la disposition des entreprises de grande taille afin de se développer en acquérant des PME. Mots clés : Fusions & Acquisitions, Tunisie, Industrie, Commerce. Classification JEL : L26, G34. *. Chercheur associé au CEPN, Université Paris 13, PRES Sorbonne Paris-Cité,. France.

  20. Characteristics of the Biological Effects and the RBE of High Energy Protons; Caracteristiques des Effets Biologiques et EBR des Protons de Haute Energie; Osobennosti biologicheskogo dejstviya i obeh protonov vysokikh ehnergii; Caracteristicas de los Efectos Biologicos y de la EBR de los Protones de Elevada Energia

    Energy Technology Data Exchange (ETDEWEB)

    Grigor' ev, Ju. G.; Darenskaja, N. G.; Domshlak, M. M.; Lebedinskij, A. V.; Nefedov, Ju. G.; Ryzhov, N. I.

    1964-03-15

    The characteristics of the biological effects of high-energy protons (120, 240 and 510 MeV) were studied in experiments on mice, rats and dogs. It was shown that together with a certain resemblance or identity in radiation damage due to the effects of X-rays and protons, there were certain differences in the case of proton irradiation. In the proton irradiation of dogs the haemorrhagic syndrome was more pronounced. Haemorrhage appeared earlier in the animals and was more abundant. A difference was found in proton RBE levels for small animals (rats, mice) and large animals (dogs). This difference is quite large and equals respectively 0.7 and 1.0 * 1.15. Some considerations are presented in the report on the cause of these differences. (author) [French] Les auteurs ont etudie les caracteristiques des effets biologiques des protons de haute energie (120, 240 et 510 MeV) au cours d'experiences sur des souris, des rats et des chiens. Ils montrent que si les dommages causes par les rayons X et les protons presentent une certaine ressemblance ou des caracteres identiques, on observe des differences dans le cas de l'irradiation par les protons. Chez les chiens exposes aux protons, le syndrome hemorragique etait plus prononce. L'hemorragie s'est manifestee plus tot chez ces animaux et etait plus abondante. Les auteurs ont decele une difference dans l*EBRdes protons pour les petits animaux (rats, souris) et pour les grands animaux (chiens). Cette difference etait importante: 0,7 dans le premier cas et de 1,0 a 1,15 dans le second cas. On trouve dans le memoire quelques considerations sur la cause de ces differences. (author) [Spanish] Los autores estudiaron las caracteristicas de los efectos biologicos de los protones de elevada energia (120, 240 y 510 MeV) mediante experimentos con ratones, ratas y perros. Comprobaron que a pesar de ciertas semejanzas en las radiolesiones causadas por los rayos X y los protones, los efectos de estos ultimos acusan algunas diferencias. El

  1. Experimental Determination of the Neutron Characteristics of UO{sub 2}-PuO{sub 2}-H{sub 2}O Lattices; Determination Experimentale Des Caracteristiques Neutroniques De Reseaux UO{sub 2}-PuO{sub 2}-H{sub 2}O

    Energy Technology Data Exchange (ETDEWEB)

    Debrue, J.; Fabry, A.; Leenders, L.; Motte, F.; Van Den Broeck, H. [Centre d' Etude de l' Energie Nucleaire, Mol (Belgium)

    1967-09-15

    combustibles mixtes UO{sub 2}-PuO{sub 2} enrichis respectivement a 3% {sup 235}U- 1% Pu fissile et 2% {sup 235}U-2% Pu fissile, et d'un combustible UO{sub 2} enrichi a 4% {sup 235}U; les teneurs isotopiques en {sup 240}Pu des deux combustibles mixtes sont en outre nettement differentes, respectivement 7 et 17%. Dans une premiere partie du programme, on etudie des reseaux reguliers dans des coeurs a deux zones cylindriques coaxiales, une zone UO{sub 2}-PuO{sub 2} et une zone UO{sub 2} ; on s'attache particulierement a explorer, de part et d'autre de la frontiere commune a ces deux zones, la region de transition dans laquelle le spectre neutronique evolue entre les distributions energetiques caracteristiques de chacun des deux reseaux. Les resultats experimentaux sont destines a l'etalonnage des methodes de calcul. Dans une seconde partie du programme, on simulera des portions du coeur du reacteur de la centrale SENA afin d'etudier les problemes particuliers au rechargement d'un tiers de ce coeur par du combustible mixte UO{sub 2}-PuO{sub 2}. Parmi les techniques experimentales mises en oeuvre a l'occasion de ces differentes experiences, on met en evidence celles qui sont les plus specifiques de la presence du plutonium: mesure de la densite de fission par comptage direct des produits de fission formes par irradiation dans le combustible mixte, mesure d'indices de spectre au moyen de detecteurs fissiles et de detecteurs presentant des resonances voisines de celles des isotopes du plutonium. Les conditions optimales d'application de ces techniques sont presentees; l'incidence des incertitudes affectant les resultats experimentaux des indices de spectre (rapports de sections efficaces) sur le cycle du combustible est discutee. Enfin, on presente brievement un programme d'essais sous-critiques conduit jusqu'a present sur deux lots de crayons combustibles UO{sub 2} enrichi a 5 et 1% {sup 235}U, dans le but d'etudier les possibilites des methodes consistant a exciter un reseau sous

  2. In-situ test of the static behaviour of a pile foundation subjected to thermo-mechanical solicitations. Intermediate report of January 1999; Test en conditions reelles du comportement statique d`un pieu soumis a des sollicitations thermo-mecaniques. Rapport intermediaire de janvier 1999

    Energy Technology Data Exchange (ETDEWEB)

    Moreni, M.; Laloui, L.; Steinmann, G. [and others

    1999-10-01

    , le transformant ainsi en pieu echangeur. Des capteurs de force, de deformation et de temperature ont ete installes afin d`evaluer l`effet de sollicitations thermiques sur la statique du pieu. La phase initiale du projet, terminee en mai 1998, comprenait la conception et la realisation du pieu echangeur ainsi que son instrumentation; la phase suivante, qui se termine un mois apres la parution du present rapport, concerne une serie de sollicitations thermiques appliquees au pieu, appelees tests, pendant cette phase de construction du batiment. Le poids supporte par le pieu a ainsi augmente d`un test a l`autre. Cette double sollicitation produit le couplage thermo-mecanique. Ce rapport presente toutes les mesures effectuees au cours des 6 tests, entre la construction de chaque etage. La variation de temperature appliquee au pieu etait de 15 K a chaque test, sauf pour le premier pour lequel elle etait de 22 K (la base du batiment n`etant pas encore construite). Les temperatures, les contraintes et les deformations ont ete mesurees a differentes profondeurs du pieu. Un enregistrement continu des mesures thermiques relatives au chauffage du pieu (temperatures, debit, puissances electrique et thermique) a egalement ete realise. Des carottages soniques et un controle par la methode de reflexion ont ete effectues pour determiner le module d`elasticite du pieu et la qualite de son beton. La derniere phase du projet (mars - decembre 1999) portera sur l`interpretation des mesures et l`evaluation de l`influence de variations de temperature sur la portance du pieu

  3. Change of I-V characteristics of SiC diodes upon reactor irradiation; Modification des caracteristiques I-V de jonctions p-n au SiC du fait d'une irradiation dans un reacteur; Izmeneniya kharakteristik I-V vyrashchennogo v SiC perekhoda tipa p-n posle oblucheniya ego v reaktore; Modificaciones que sufren por irradiacion en un reactor las caracteristicas I-V de uniones p-n en SiC

    Energy Technology Data Exchange (ETDEWEB)

    Heerschap, M; De Coninck, R [Solid State Physics Dept., SCK-CEN, Mol (Belgium)

    1962-04-15

    In search for semiconductors, which can be used in high-flux reactors in order to measure flux distributions, we irradiated SiC p-n junctions in the Belgium BR-1 reactor. Two types of SiC-diodes of different origin have been irradiated. These junctions are grown in the Lely-furnace. The change in forward and reverse characteristics have been measured during and after irradiation up to temperatures of 150{sup o}C, while measurements up to a temperature of 500{sup o}C are in progress. It has been found that one type resists BR-1 neutrons up to an integrated flux of 10{sup 15} n/cm{sup 2}, while the other resists irradiation up to a flux of 10{sup 17} n/cm{sup 2}. The changes in characteristics are given as well as the result of some annealing experiments. (author) [French] En recherchant des semi-conducteurs pouvant servir a mesurer les distributions de flux dans les reacteurs a haut flux de neutrons, les auteurs ont irradie des jonctions p-n au SiC dans le reacteur belge BR-1. Deux types de diodes a SiC d'origines differentes ont ete ainsi irradies. Les jonctions en question sont preparees par etirage dans le four Lely. Les auteurs ont mesure les modifications subies par les caracteristiques I-V apres et pendant l'irradiation a des temperatures allant jusqu'a 150{sup o}C; ils poursuivent leurs mesures dans la gamme des temperatures allant de 150{sup o}C a 500{sup o}C. Us ont constate que l'un des types de diode a SiC resiste aux neutrons du reacteur BR-1 jusqu'a 10{sup 15} n/cm{sup 2}, tandis que l'autre type resiste a l'irradiation jusqu'a 10{sup 17} n/cm{sup 2}. Les auteurs indiquent les modifications subies par les caracteristiques, ainsi que le resultat de certaines experiences de recuit. (author) [Spanish] Los autores estan tratando de encontrar semiconductores con los que sea posible medir distribuciones de flujo en reactores de flujo elevado, y con este fin irradiaron uniones p-n del SiC en el reactor BR-1 de Belgica. Irradiaron dos tipos de diodos de SiC de

  4. Influence of hydrogen on metals behavior. 1 - Mechanical behavior of Ti 6 pc Al 6 pc V 2 pc Sn titanium alloy versus hydrogen: influence of heat treatment and of oxygen content; Influence de l'hydrogene sur le comportement des metaux. 1 - comportement mecanique de l'alliage de titane T A6 V6 E2 vis-a-vis de l'hydrogene: influence du traitement thermique et de la teneur en oxygene

    Energy Technology Data Exchange (ETDEWEB)

    Schaller, Bernard

    1972-06-26

    The mechanical behavior of Ti 6 pc Al 6 pc V Sn alloy during dynamic testing has been investigated versus hydrogen and oxygen content. The hydrogen susceptibility depends only slightly on its microstructure, acicular or equi-axed: it depends much more on conditions of hydrogen contamination and on the thermal history afterward. When the alloy has been stabilized by annealing in {alpha} - {beta} and provided hydrogen absorption does not induce phase transformations, hydrogen sensitivity is relatively low: brittleness occurs suddenly but at a high concentration threshold (2000 ppm H), which coincides with hydrogen saturation of {beta} phase. When the alloy includes unstabilized phases, its response to hydrogen changes whether it has been finally annealed or not, in the 300 - 500 C temperature area, prone to {omega} phase formation. In the absence of such an annealing, a reduction in ductility only occurs at high concentrations (> 1500 ppm H). In the other and, after annealing at 400 C, alloy hardening and a ductility decrease start even at the lowest hydrogen amounts: then hydrogen susceptibility is very high. Low oxygen concentration (up to 2000 ppm) do not sensibly affect the good hydrogen tolerance of this alloy. Beyond 2500 ppm, oxygen, while improving tensile strength, yet severely decreases ductility. [French] Le comportement mecanique de l'alliage TA6-V6-E2 lors d'un essai dynamique a ete etudie en fonction de la teneur en hydrogene et en oxygene. La sensibilite vis-a-vis de l'hydrogene ne depend que tres faiblement de sa structure migrographique, aciculaire ou equiaxe; elle depend bien plus des conditions de contamination par l'hydrogene et de son histoire thermique apres contamination. Lorsque l'alliage a ete stabilise par un recuit dans le domaine biphase, et a condition que l'absorption d'hydrogene n'entraine pas de modification structurale, la sensibilite vis-a-vis de l'hydrogene est relativement faible: la fragilite apparait brutalement mais pour un

  5. Mechanical pumps for liquid metals; Pompes mecaniques pour metaux liquides

    Energy Technology Data Exchange (ETDEWEB)

    Baumier, J; Gollion, H J [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1964-07-01

    The pumping of liquid metals by centrifugal pumps poses two principal problems. These are hermetic sealing of the rotating shaft and, its guidance where immersed in liquid metal. The solutions to the problems used on 13 experimental pumps are given here. The resolution of the guidance problem consists in the majority of cases in the utilisation of hydrostatic bearings. Accordingly, a theoretical study was instituted for the first time to calculate the bearings of the earlier pumps. After this, an experimental study was carried out, to check the theory by water tests. A relation for bearing calculation of pumps with diffusers is proposed. Finally the influence of the bearing elasticity on the shafts critical speed is studied. (authors) [French] Le pompage des metaux liquides, par des pompes centrifuges, pose 2 principaux problemes, qui sont: d'une part, la realisation d'une excellente etancheite au passage de l'arbre, d'autre part, son guidage sur la partie immergee dans le metal liquide. Les solutions retenues pour resoudre ces problemes sur 13 pompes experimentees sont presentees. Le probleme du guidage de l'arbre, a dans la majorite des cas ete resolu en utilisant un palier hydrostatique, aussi l'etude en a d'abord ete approfondie de facon theorique pour calculer les paliers des premieres pompes, puis experimentale pour controler la theorie, en effectuant des essais a l'eau. On propose une relation pour calculer les paliers des pompes a diffuseurs. On a en outre effectue une etude de l'influence de l'elasticite du palier hydrostatique sur la vitesse critique de l'arbre. (auteurs)

  6. Diverses questions de mecanique et de thermodynamique classiques et relativistes

    Science.gov (United States)

    de Broglie, Louis; Lochak, Georges; Karatchentzeff, Michel; Fargue, Daniel

    Ce livre reproduit un cours inédit de Louis de Broglie, de 1948, dans lequel il réexamine, gráce à la relativité, les analogies entre la mécanique et la thermodynamique étudiés par Helmholtz, Boltzmann et Planck avant le succès de la mécanique statistique. C'est le premier d'une série de travaux de de Broglie en vue de prolonger sa découverte de 1924 vers une mécanique ondulatoire des processus irréversibles, en unifiant les principes de Fermat, de Maupertuis et de Carnot-Clausius. L'intérêt du livre est triple: 1. une généralisation de la mécanique quantique qui décrirait les transitions quantiques en tant que processus dynamiques; 2. revisiter la physique classique en compagnie de l'un des plus grands physiciens du siècle 3. découvrir quelques grands idées oubliées de la physique classique.

  7. Caracterisation physique et mecanique de la graine de nere( Parkia ...

    African Journals Online (AJOL)

    The seed of Néré Parkia biglobosa is an agricultural product very rich in proteins and lipids. Traditional process for transformation of Néré seed in food (mustard) consists on several operations of which seed dehulling stays the most tiresome and least hygienic. Physical and mechanical properties of seeds are required in ...

  8. The Main Technological Characteristics of Apparatus for Industrial Radiochemical Processes, in Particular Ethylene Polymerization; Caracteristique techniques fondamentals des appareils pour l'application industrielle de reactions chimiques sous rayonnement (notamment la polymerisation de l'ethylene ); Osnovnye tekhnologicheskie kharakteristiki apparatov dlya provedeniya radiatsionno-khimi-cheskikh protsessov (v chastnosti, dlya polimerizatsii ehtilena) v promyshlennom masshtabe; Principales caracteristicas tecnologicas de los aparatos para la aplicacion industrial de reacciones radioquimicas

    Energy Technology Data Exchange (ETDEWEB)

    Syrkus, N P; Breger, A K; Weinstein, B I [Karpov Physicochemical Institute, Moscow, USSR (Russian Federation)

    1960-07-15

    The paper gives a general review of some of the main technological features of apparatus, for instance spherical apparatus, for industrial radiochemical processes. A method is proposed for estimating the effectiveness of apparatus of any given construction by comparing it with the output of an infinitely large apparatus having the same radiation source. An account is given of the technological features of an apparatus for radio-polymerizing ethylene at 200 atmospheres and 25{sup o}C{sup 1} with a rodshaped gamma-radiation source (Co{sup 60}) of variable activity. This apparatus can be designed to suit the mean dose rate which the power efficiency of the apparatus allows. It is shown that the yield, Q, of the apparatus is, other things being equal, a constant ration of the power, W{sub 0}, of the gamma-radiation of the apparatus. In the apparatus reviewed, Q {approx} W{sub 0}{sup 0,5}. (author) [French] Le memoire contient un expose general des caracteristiques techniques essentielles des appareils, par exemple d'un appareil du type spherique, pour l'application industrielle de reactions chimiques sous rayonnement. Le memoire propose une methode pour evaluer l'efficacite d'appareils de tous types en comparant la productivite de chaque modele avec celle d'un appareil infiniment grand, alimente par une source de rayonnement identique. Le memoire indique le calcul des caracteristiques techniques de l'appareil destine a la polymerisation sous rayonnement de l'ethylene (pression : 200 atmospheres, temperature: 25{sup o}C{sup 2} avec une source allongee de rayonnement gamma Co{sup 60} pour diverses activites. Un appareil de ce type peut etre calcule selon les valeurs moyennes de l'intensite des doses, determinees selon la valeur du coefficient d'efficacite totale energetique de l'appareil. On constate que la productivite (Q) de l'appareil, toutes choses egales d'ailleurs, est puissance de l'intensite (W{sub 0}) du rayonnement gamma de l'appareil. Pour l'appareil considere

  9. Efficiency of the Shut-Down and Safety Equipment and the Kinetic Characteristics of the G2 and G3 Reactors; Efficacite des dispositifs de secours et de securite et caracteristiques cinetiques des piles G2 et G3; Ehffektivnost' sistem avarijnoj zashchity reaktorov G.2 i G.3 i kineticheskie kharakteristiki ehtikh sistem; Caracteristicas cineticas y eficacia de los dispositivos de auxilio y de seguridad de los reactores G2 y G3

    Energy Technology Data Exchange (ETDEWEB)

    Henri, C.; Plisson, J.; Teste duBailler, A. [Centre d' Etudes Nucleaires de Saclay (France)

    1963-10-15

    securite. Les performances et les ameliorations successives apportees a ces installations sont mentionnees. Les caracteristiques intrinseques de securite de ces piles sont mises en evidence par l'etude experimentale de leur comportement en regime transitoire. Ces etudes permettent de s'assurer de la validite de modeles de calcul. Ces programmes de calcul machine peuvent ensuite etre utilises pour l'etude des consequences des accidents possibles. L'accident de depressurisation est particulierement etudie en tenant compte des performances des dispositifs de surete installes. (author) [Spanish] La experiencia adquirida durante varios afios de explotacion de los reactores G2 y G3 permite confirmar el alto grado de seguridad de funcionamiento de los reactores del tipo uranio natural-grafito-anhidrido carbonico. La memoria describe por una parte, las instalaciones fijas de auxilio y de seguridad que permiten superar incidentes tales como falta de alimentacion de la red de distribucion, paro de los sopladores, interrupcion del suministro de agua, etc., y por otra, accidentes com o la ruptura de una vaina, sobrecalentamientos locales, escape del fluido intercambiador de calor, etc.; asimismo, explica su functionamiento por medio de esquemas, examinando principalmente: a) la distribucion ''potencia'' y ''control'' de las instalaciones con sistemas de auxilio, b) la distribucion de agua por sistemas de auxilio; c) la cadena de seguridad. La memoria menciona los rendimientos y las mejoras introducidas sucesivamente en estas instalaciones. El estudio experimental de su comportamiento en regimen transitorio pone en evidencia las caracteristicas de seguridad intrinseca de estos reactores. Estos estudios permiten comprobar la validez del modelo utilizado para el calculo. Los programas para las calculadores pueden servir despues para el estudio de las consecuencias de los posibles accidentes. Estudia en particular la caida de presion accidental, teniendo en cuenta la eficacia de los

  10. Influence of Aerosol Properties and the Respiratory Pattern upon Hazards Evaluation following Inhalation Exposure; Influence des Caracteristiques des Aerosols et du Regime de la Respiration sur l'Evaluation des Risques, a la Suite d'une Exposition par Inhalation; Vliyanie svojstv aehrozolej i obraztsa respiratora na otsenku opasnosti oblucheniya pri vdykhanii radioaktivnykh veshchestv; Influencia de las Propriedades de los Aerosoles y de su Esquema Repiratorio en la Evaluacion de los Riesgos Consecutivos a una Exposicion por Inhalacion

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, R. G. [Lovelace Foundation for Medical Education and Research, Albuquerque, NM (United States)

    1964-10-15

    ont ete faites sur des animaux en vue d'etablir une correlation entre, d'une part, certaines caracteristiques physiques et chimiques des particules inhalees et, d'autre part, les trois parametres biologiques mentionnes ci-dessus. L'auteur indique des valeurs de la quantite deposee, selon les emplacements et en fonction de la dimension des particules inhalees, pour un compose soluble dans le tissu (chlorure de cesium) et pour un autre qui ne l'est pas (chlorure de thorium). Il se base sur certaines donnees pour expliquer les variations que subissent la repartition tissulaire et l'excretion d'un element, selon l'etat physique et chimique dans lequel il se trouve lors de l'inhalation. Il se sert de donnees provenant d'experiences sur des aerosols de nombreux composes, y compris ceux qui ont deja ete mentionnes, pour montrer qu'il existe une correlation exceptionnelle entre la charge corporelle et l'excretion dans les matieres fecales durant les quelques premiers jours qui suivent l'exposition. Il indique quels sont, aux fins des dosages biologiques, les avantages qu'il y a a analyser a la fois les urines et les matieres fecales. En prenant comme exemple les donnees susmentionnees, l'auteur souligne dans tout le memoire les erreurs que comportent les methodes couramment utilisees pour evaluer les risques par les procedes d'echantillonnage et d'analyse biologique de l'air. (author) [Spanish] Para evaluar los riesgos derivados de la penetracion de sustancias radiactivas en el organismo por una via cualquiera, son tres los parametros biologicos importantes que es preciso conocer: 1) la cantidad depositada en el organismo, 2) la cinetica de distribucion y translocacion dentro del organismo, 3) la velocidad de eliminacion de la sustancia por excrecion. Por lo general, en el caso de una exposicion accidental, se carece de datos cuantitativos suficientes sobre estos puntos. En la memoria se describen los estudios realizados con animales de laboratorio para correlacionar las

  11. Characteristic properties of crystals. Their demonstration; Proprietes caracteristiques des cristaux. Mise en evidence

    Energy Technology Data Exchange (ETDEWEB)

    Lesueur, C

    1951-03-01

    The characteristic properties of scintillation crystals discussed are the photon spectrum emitted by passage of a particle, number of these photons, transparence of the crystal to its own fluorescence radiation, and decay period of the fluorescence. The experimental apparatus, consisting of photomultiplier tube, preamplifier, amplifier, discriminator, and scaler, is described, and the experimental evaluation of the characteristic properties is discussed. Results of tests on various crystals with {alpha} and {beta} radiations are reported graphically.

  12. Silicon on insulator technology. Characteristics. Applications; Technologies silicium sur isolant. Caracteristiques. Exemples d'application

    Energy Technology Data Exchange (ETDEWEB)

    Suat, J. P.; Peccoud, L.; Le Goascoz, V.; Garcia, M.; Mackowiak, E.

    1975-01-31

    The advantages resulting from a SOS (Silicon-on-Sapphire) MOS technology are demonstrated. Experimental results giving the performance of C.MOS and depletion-enrichment P-channel technologies are presented, with an application of Silicon on insulator on development, that is to say a 1024 bits MNOS memory, peripheral circuits being developed according to the depletion-enrichment technology.

  13. Uncertainties on decay heat power due to fission product data uncertainties; Incertitudes sur la puissance residuelle dues aux incertitudes sur les donnees de produits de fission

    Energy Technology Data Exchange (ETDEWEB)

    Rebah, J

    1998-08-01

    Following a reactor shutdown, after the fission process has completely faded out, a significant quantity of energy known as 'decay heat' continues to be generated in the core. The knowledge with a good precision of the decay heat released in a fuel after reactor shutdown is necessary for: residual heat removal for normal operation or emergency shutdown condition, the design of cooling systems and spent fuel handling. By the summation calculations method, the decay heat is equal to the sum of the energies released by individual fission products. Under taking into account all nuclides that contribute significantly to the total decay heat, the results from summation method are comparable with the measured ones. Without the complete covariance information of nuclear data, the published uncertainty analyses of fission products decay heat summation calculation give underestimated errors through the variance/covariance analysis in consideration of correlation between the basic nuclear data, we calculate in this work the uncertainties on the decay heat associated with the summation calculations. Contribution to the total error of decay heat comes from uncertainties in three terms: fission yields, half-lives and average beta and gamma decay energy. (author)

  14. ETUDE DU COMPORTEMENT MECANIQUE DES ACIERS HYPEREUTECTOIDES DANS LE DOMAINE DE TEMPERATURE INTERCRITIQUE DYNAMIQUE

    Directory of Open Access Journals (Sweden)

    R GHERIANI

    2001-06-01

    Full Text Available L'étude que nous présentons contribue à une meilleure compréhension de l'influence de la vitesse de déformation et de la température sur le comportement mécanique des aciers hypereutectoïdes dans le domaine de température intercritique dynamique. Les courbes expérimentales obtenues en torsion présentent un intérêt notable dans la mesure où elles permettent de caractériser le comportement mécanique de l'acier 100C6; de plus, elles fournissent  des informations précieuses sur la capacité maximale de déformation de l'alliage. Les essais de torsion, menés jusqu'à rupture des éprouvettes, permettent d'effectuer un classement des matériaux selon leur ductilité. Les résultats obtenus sur l'acier 100C6 ont permis de préciser le comportement mécanique à tiède  de cet acier. Les aciers hypoeutectoïdes présentent, dans les domaines de température compris entre Ac1 et Ac3 en condition dynamique, une capacité de déformation élevée résultant de l'évolution, en cours de déformation, des phases a et g et de leurs mécanismes d'adoucissement. Nous nous sommes alors posé la question: quel est le comportement d'un acier hypereutectoïde, donc ne présentant  pas de domaine biphasé (a + g à l'équilibre, lorsqu'il est déformé à une température supérieure à Ac1?

  15. Conception, analyse et caracterisation des proprietes mecaniques de ressorts composites a renfort tresse

    Science.gov (United States)

    Zebdi, Oussama

    High performance composites reinforced by woven or braided fabrics have several different applications in various fields such as in the aerospace, automobile and marine industry. This research project was carried out at the Ecole Polytechnique de Montreal in collaboration with an industrial sponsor, the company Composites Atlantic Ltd. Composite springs often represent an interesting alternative, given the reduction in weight that they allow with equal mechanical performance compared to metallic springs. Their good resistance to fatigue and corrosion bring additional benefits in several industrial applications. Moreover, the use of the composites increases safety by avoiding the risks of brutal rupture because of the low propagation velocity of cracks in this type of material. Lastly, in electrotechnics, another significant advantage comes into play because of the electrical insulation capability of composite springs. Few research results can be found on composite springs in the scientific literature. The first part of this thesis studies the problems connected with the design of composite springs. The results are promising, because it was confirmed that composite springs can be devised with the same mechanical performance in term of stiffness as metallic ones. Two solutions were found to replace the metallic springs of the suspension of a four wheel drive: the first spring was in carbon-epoxy, and the second one in glass-epoxy. In the second part, software was developed in order to devise a new approach to predict the mechanical properties of woven or braided composites. This work shows how an inverse method based on plate laminate theory allows creating, from experimental results on braided composites, a virtual basic ply that includes the effect of fiber architecture (undulation and braiding angle). Using this model, the properties of the composite can be predicted for any braid angle. The comparison with the experimental results shows a good correlation with numerical predictions. In third part, an experimental study on creep was conducted on composite plates manufactured with the same constitutive materials as the composite springs. Creep tests in three point bending were carried out with Q800 DMA machine. The results showed that creep behavior depends primarily on the polymer matrix. However, rigidity is a function of the fiber-matrix mixture. The braiding angle of 35° corresponds to a characteristic threshold for braided composites: beyond this value, rigidity falls in a creep test at a temperature higher than Tg. It represents also a critical angle in bending or in tensile tests. Above 35°, the failure mode of the composite goes from fragile (rupture of fibers) to a mixed mode, in which the polymer matrix comes also into play with fibers. A good stability was observed for the composites with a braiding angle lower than +/- 35° or higher than +/-60°. Long-term tests were also carried out for two braided composites at +/- 45° and +/- 55° in order to check the predictive model of the DMA. The shift factors obtained from the short and long term tests are roughly equal. This thesis has set the ground for the future development on industrial applications of composite springs. The design software predicts the mechanical effectiveness of helical composite springs. The software developed to predict the elastic properties of braided composites accelerates the preparation of characterization results for the design stage. This numerical tool could be generalized for other fiber architectures. It represents a practical tool for further investigations. Finally, the study on creep, although preliminary, provides a first evaluation of the life cycle of composite springs. It would be interesting to proceed now to the design of a first industrial application.

  16. An overview of studies in structural mechanics; Panorama des etudes en mecanique des structures

    Energy Technology Data Exchange (ETDEWEB)

    Guilbaud, D.; Blay, N.; Broc, D.; Chaudat, T.; Feau, C.; Sollogoub, P.; Wang, F.; Baj, F.; Bung, H.; Combescure, D.; Lepareux, M.; Phalippou, C.; Bentejac, F.; Hourdequin, N.; Laporte, T.; Millard, A.; Nicolas, L.; Chapuliot, S.; Fissolo, A.; Gourdin, C.; Kayser, Y.; Marie, S.; Reytier, M.; Yuritzinn, T.; Magnaud, J.P. [CEA Saclay Dept. Modelisation de Systemes et Structures, 91 - Gif sur Yvette (France); Braillard, O.; Collard, B.; Gobillot, G.; Mori, V.; Vallory, J.; Pascal-Ribot, S.; Pluyette, E. [CEA Saclay, Dept. de Technologie Nucleaire, 91 - Gif sur Yvette (France); Berton, M.N.; Cabrillat, M.T.; Lejeail, Y. [CEA Saclay, Dept. d' Etudes des Reacteurs, 91 - Gif sur Yvette (France)

    2006-07-01

    The present report gives an overview of the ongoing research programmes in structural mechanics at CEA/DEN. On the whole, these contributions are well representative of the research work performed, more oriented by engineering concerns than driven by pure academic goals. Fundamentally, the developed knowledge results in new methods and improved engineering and computational tools that can be used for CEA needs and transferred to industrial clients and partners. Basic research is carried out with the help of university laboratories, what allows CEA teams to identify the underlying problems and to address them in an adequate manner. Confrontation with other viewpoints and backgrounds takes place in international cooperative actions conducted with academic or industrial research centres, often giving rise to benchmarks. Due to the wide range of problems submitted to CEA/DEN, the R and D topics are numerous and the effort devoted to each of them is limited and sometimes not continuous. Basic research is of course more limited and needs thorough preparation in order to ensure that the key questions, which lock the progress, are really addressed.. Before to end, it is worth mentioning two original research actions which have begun: -) identification of medium state and representation of its variability by a probabilistic approach: this original approach couples inverse method an probability to obtain non directly measurable value from global effect on structures (for example deduce damage from the displacement of a loaded beam) and should be applied to non destructive identification of present state of nuclear reactor enclosures, -) a program of numerical simulations of fluid-elastic instability of a tube bundle submitted to cross flow has been initiated with an Arbitrary Lagrangian Eulerian -ALE- finite element method to obtain a better knowledge and understanding of the phenomenon. From these simulations, the evolutions of pressure and velocity fields close to fluid-elastic instability velocity are being obtained. Moreover, influence of non-dimensional parameters that are characteristic of the coupled problem (Reynolds number, Stokes number, reduced velocity) and their influence on the evolution of modal parameters (added mass, damping and thickness) is being studied through parametric studies. The research actions described here, and those in progress are in agreement with the general pattern of the 'Mechanics 2010' program, but nevertheless the R and D effort is less extensive than it was expected. So, this activity would also deserve more effort in transverse fields like probabilistic methods, innovative measuring techniques and numerical methods. (authors)

  17. Energy conservation in mechanical industry; Maitrise de l`energie dans les industries mecaniques

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-31

    The workshop is composed of 12 communications on the theme of energy consumption, conservation and management in industry, and more especially in metal industry: evaluation of the energy savings potential in the French industry; official energy diagnosis procedure in buildings; the French national gas utility policy for energy conservation and economical performance in industry; energy conservation with speed variators for electric motors; energy audits and energy metering for conservation objectives. Examples of energy efficient systems or energy audits in various industrial sectors (compressed air, industrial buildings, heat treatments, curing...) are also presented. The electric power quality EDF`s contract is also discussed

  18. Angular analyses in relativistic quantum mechanics; Analyses angulaires en mecanique quantique relativiste

    Energy Technology Data Exchange (ETDEWEB)

    Moussa, P [Commissariat a l' Energie Atomique, 91 - Saclay (France). Centre d' Etudes Nucleaires

    1968-06-01

    This work describes the angular analysis of reactions between particles with spin in a fully relativistic fashion. One particle states are introduced, following Wigner's method, as representations of the inhomogeneous Lorentz group. In order to perform the angular analyses, the reduction of the product of two representations of the inhomogeneous Lorentz group is studied. Clebsch-Gordan coefficients are computed for the following couplings: l-s coupling, helicity coupling, multipolar coupling, and symmetric coupling for more than two particles. Massless and massive particles are handled simultaneously. On the way we construct spinorial amplitudes and free fields; we recall how to establish convergence theorems for angular expansions from analyticity hypothesis. Finally we substitute these hypotheses to the idea of 'potential radius', which gives at low energy the usual 'centrifugal barrier' factors. The presence of such factors had never been deduced from hypotheses compatible with relativistic invariance. (author) [French] On decrit un formalisme permettant de tenir compte de l'invariance relativiste, dans l'analyse angulaire des amplitudes de reaction entre particules de spin quelconque. Suivant Wigner, les etats a une particule sont introduits a l'aide des representations du groupe de Lorentz inhomogene. Pour effectuer les analyses angulaires, on etudie la reduction du produit de deux representations du groupe de Lorentz inhomogene. Les coefficients de Clebsch-Gordan correspondants sont calcules dans les couplages suivants: couplage l-s couplage d'helicite, couplage multipolaire, couplage symetrique pour plus de deux particules. Les particules de masse nulle et de masse non nulle sont traitees simultanement. Au passage, on introduit les amplitudes spinorielles et on construit les champs libres, on rappelle comment des hypotheses d'analyticite permettent d'etablir des theoremes de convergence pour les developpements angulaires. Enfin on fournit un substitut a la notion de 'portee du potentiel', d'ou resulte la presence a basse energie des facteurs dits 'de barriere centrifuge'. La presence de ces facteurs n'avait jamais ete deduite d'hypotheses compatibles avec l'invariance relativiste. (auteur)

  19. LES RELATIONS ENTRE L’ERODABILITE DES SOLS ET LEURS PROPRIETES PHYSICO-MECANIQUES

    Directory of Open Access Journals (Sweden)

    I. C. Stanga

    2005-10-01

    Full Text Available L’érodabilité représente la susceptibilité des sols d’être érodés sous l’action des pluies, du ruissellement ou du vent. Cette susceptibilité est conditionnée par les propriétés physico-chimiques des sols. Dans l’article ci-dessous, on montre les relations qui existent entre l’érodabilité et les propriétés physico-mécaniques des sols, dont les plus importantes sont la granulométrie (surtout le rapport entre différentes fractions texturales, la structure, la densité, la permeabilité et la conductivité hydrauliques.

  20. Space Vehicle Flight Mechanics (La Mecanique du Vol des Vehicules Spatiaux)

    Science.gov (United States)

    1990-06-01

    Space Telescope, an astrophysics spacelab mission, Astro , the Gamma Ray Observatory, Spacelab Life Sciences -1 and ESA/NASA Ulysses. The Great...all the hardware/avionics subsystems, the flight software, and the astro - nauts. Here, the software and the interfaces can be thoroughly checked out...rm6di ai re de Il’angl e G ,(F,,, Fz,)~ = h,, 7 (171) de rotatioa des axes lies 5 la Terre F ,U3P rapport aux axes Fxc ; (Fg.30. Iqest la vitesse de

  1. Methodes non perturbatives en mecanique quantique et en theorie des champs quantiques

    Science.gov (United States)

    Jirari, Hamza

    2001-10-01

    Nous construisons un hamiltonien effectif à partir de l'intégrale de chemin via la méthode Monte-Carlo. Cet hamiltonien décrit les phénomènes physiques dans le domaine de basse énergie. Nous déterminons le spectre d'énergie et les fonctions d'ondes de plusieurs systèmes quantiques. Les résultats obtenus montrent que cette nouvelle approche Monte-Carlo hamiltonienne fonctionne. En mécanique quantique, nous suggérons une expression analytique de l'intégrale de chemin en introduisant une action quantique avec des paramètres renormalisés. Nous présentons des résultats numériques pour quelques potentiels locaux. Cette action quantique offre la possibilité de comparer l'évolution classique et quantique et permet de quantifier les instantons classiques et éventuellement le chaos classique. Nous investiguons la QCD sur un réseau bidimensionnel en utilisant une version améliorée des fermions de Wilson. Nous montrons que la théorie améliorée conduit à une réduction significative des erreurs dues à la valeur finie du pas du réseau. Nous calculons le condensat chiral et la masse de l'état lié quark-antiquark. Nous aboutissons à une bonne concordance entre nos résultats numériques et les résultats analytiques du modèle dans le continu.

  2. ETUDE DU COMPORTEMENT MECANIQUE DU BETON CELLULAIRE AUTOCLAVE PRODUIT EN ALGERIE

    Directory of Open Access Journals (Sweden)

    R BELOUETTAR

    2002-12-01

    Full Text Available Ce travail présente une étude expérimentale du comportement mécanique du béton cellulaire autoclavé. L’étude est portée essentiellement sur une série d’essais mécaniques en compression quasistatique à différentes vitesses de déformation variables entre 10-4 s-1 et 10 s-1 et à deux états différents (état sec et état saturé d’eau. En général, l’augmentation de la vitesse de déformation donne une augmentation de la contrainte critique du béton cellulaire autoclavé. Le béton cellulaire autoclavé présente une sensibilité à la vitesse de déformation positive. La valeur du module d’élasticité est proche de la valeur standard (1.5 GPa pour un béton cellulaire autoclavé de masse volumique égale à 500-550 kg/m3.

  3. La coherence conceptuelle d'etudiants collegiaux en mecanique Newtonienne et en metrologie

    Science.gov (United States)

    Periard, Martin

    This thesis evaluates the coherence of the conceptual network demonstrated by college students in life and applied sciences. This evaluation was based on the analysis of Burt tables issuing from multiple choice questionnaires, on the creation and careful examination of a novel tool, the matrix of specific discrimination coefficients, which will be described in the main text, and on the qualitative analysis of actual laboratory work of students doing an experimentation. At the completion of this project, four research axis have been explored. (1) What is the conceptual coherence demonstrated in Newtonian mechanics? (2) Is the mastery of uncertainty quantification related to the development of logical thinking or to mathematical competency? (3) What is the conceptual coherence demonstrated in the quantification of experimental uncertainty? (4) What are the concrete procedures utilized by students to quantify experimental uncertainty in a semi-directed laboratory context? The main conclusions that emerged from each axis of research can be summerized as follow. (1) The most prevalent erroneous conceptions are not solidly set in a rigid conceptual network. For example, a student successful in a question about Newton's third law (the most difficult subject of the Force Concept Inventory) is just slightly more likely to succeed in another related question than the other participants. Many pairs of questions displays a negative specific discrimination coefficient demonstrating a weak conceptual coherence in pre-test and a somewhat ameliorated conceptual coherence in post-test. (2) If a small proportion of students has demonstrated marked deficiencies in questions related with control of variable and in those related to the relationship between the graphical display of experimental data and a mathematical model, the majority of students can be considered as adequately mastering those subjects. However, almost every student demonstrated a lack of mastery of concepts underlying the quantification of experimental uncertainty and the propagation of uncertainty (heretofore referred to as metrology). No statistically significant correlation has been observed between the three main topics suggesting that they are largely independent cognitive abilities. Burt table has demonstrated a greater degree of conceptual coherence between control of variables questions than suggested by Pearson correlation coefficients. Equivalent question in the topic of metrology did not permit to demonstrate a clear conceptual coherence. (3) Analysis of a questionnaire entirely devoted to metrology has shown erroneous conceptions caused by prior learning (didactical obstacles), erroneous conceptions based on intuitive models and a lack of global comprehension of metrological concepts although some appear to be almost acquired. (4) When doing real experiments in semi-directed laboratory, students demonstrated the same difficulty identified in the questionnaire of 3) which could interpreted as corroborating previously obtained results. However, many unanticipated behaviors related to measurement were observed that could not have been anticipated solely by analyzing answers in the multiple-choice questionnaire. Interviews immediately following each semi-directed laboratory permitted the participants to detail certain aspects of their metrological methodology. Most notably, the use of repeated measurement strategies, their "spontaneous" strategies to quantify uncertainty, and their explanation of numerical estimates of reading uncertainties. Overall, uncertainty propagation algorithms were adequately employed. Many erroneous metrological conceptions seem to resist strongly to be modified by learning. Among others, assignation of the resolution of a digital scale as the uncertainty value and the lack of stacking strategies to diminish uncertainty. The conception that a numerical value cannot be more precise than the tolerance of an instrument seems firmly set. Key words. Burt tables, conceptual coherence, experimental uncertainty, laboratories, metrology, Newtonian mechanics, uncertainty propagation.

  4. Prognosis factors of thyroid micro carcinomas and recurrences characteristics; Facteurs pronostiques des microcarcinomes thyroidiens et caracteristiques des recidives

    Energy Technology Data Exchange (ETDEWEB)

    Habbeche, M.; Oufriha, N.; Nezzar, A.; Othmane, S.; Khelifa, A.; Drahmoune, R.; Bellazoug, K.; Bouyoucef, S.E. [CHU Bab El Oued, Service de medecine nucleaire, Alger (Algeria)

    2010-07-01

    Purpose: The aim of this study is the presentation of compiled series including 142 cases of thyroid micro carcinomas observed between 1993 and 2008, the description of recurrences and the discussion of iodine 131 contribution in the therapy choices. Conclusions: Frequency of local recurrence is linked to age (under 45 years), to the size of the micro carcinoma and the presence or not of peripheral ipsilateral lymphadenectomy. In this series, all patients that had lymphadenectomy have not recurred. Bi laterality and capsular break are not causes of the recurrences. (N.C.)

  5. Converters and electric machines. Solid insulating materials. Electrical characteristics; Convertisseurs et machines electriques. Materiaux isolants solides. Caracteristiques electriques

    Energy Technology Data Exchange (ETDEWEB)

    Anton, A. [Institut National Superieur de Chimie Industrielle, 76 - Rouen (France)

    2003-08-01

    The aim of this article is to allow a preselection of a solid insulating material using the most common electrical characteristics: tangent of the loss angle, relative permittivity, dielectric rigidity, superficial resistivity, transverse resistivity, resistance to high voltage creeping spark currents, index of creeping resistance. The characteristics of the main solid insulating materials are presented in tables for: thermoplastics, thermosetting materials, natural insulating materials, mineral insulating materials, rubber and synthetic elastomers, stratified insulating materials, thermoplastic films, composite synthetic papers. A comparison is made between the different materials using the three properties: tangent of the loss angle, relative permittivity and resistance to HV spark creeping currents. (J.S.)

  6. INFLUENCE DU TRAITEMENT THERMIQUE SUR LES CARACTERISTIQUES TECHNOLOGIQUES DE LA VIANDE DE BOEUF MATURE AVEC BROMÉLINE

    Directory of Open Access Journals (Sweden)

    Felicia Dima

    2010-12-01

    Full Text Available Researches have been conducted on adult beef meat after 24 hours of slaughter. Proteolytic enzyme was added in different concentrations in the injection brine and then beef cuts were injected with different percentages of brine (10, 15% v/w. Effects generated by injecting samples of adult beef with bromelin were revealed after 24 – 48 hours of storage at 4 °C. For all treatments studied, pH values increased, the largest increases were observed in samples injected with the highest levels of bromelin and brine. Effect of exogenous proteolytic enzyme on the thermal losses of adult beef was influenced by enzymatic treatment conditions. Enzymatic tenderization with bromelin had a negative effect on water holding capacity of adult beef, causing a decrease compared with control samples. Increase of bromelin added brine, ageing time and the amount of brine injected decreased water holding capacity. Analytical data showed the tenderizing effect of bromelin, rigidity index values of the samples injected with bromelin being superior to control samples.

  7. Characteristics of pumps when used as turbines; Projet 'Caracteristiques des pompes fonctionnant en turbines'

    Energy Technology Data Exchange (ETDEWEB)

    Arpe, J.; Prenat, J. [Ecole d' ingenieurs de Geneve, Geneve (Switzerland); Dubas, M.; Biner, H.-P. [Haute Ecole valaisanne, Sion (Switzerland)

    2006-07-01

    This comprehensive final report for the Swiss Federal Office of Energy (SFOE) takes a look at the state of the art concerning the use of pumps as turbines to drive the generators of small hydro-electric schemes. The method proposed is based on the determination of a model which computes the total head losses in pump operation with the help of pump geometry. Then, this model is applied to determine the characteristics to be expected in turbine operation. For this project, five pump geometries were used in order to verify the model. As a result, the modelling of losses allows a prediction of the head at the best efficiency point (BEP) in pump operation with an error of between 4 and 5%. The authors state that software programmed in Excel has been developed and will be available for free use. Also, a laboratory test rig is described. The mathematical modelling of the pump/turbine is presented in detail.

  8. Incidence et Caracteristiques des Signalements d'Enfants Maltraites: Comparaison Interculturelle (Incidence and Characteristics of Reported Child Abuse: Intercultural Comparisons).

    Science.gov (United States)

    Tourigny, Marc; Bouchard, Camil

    1994-01-01

    Analysis of 953 reports of child abuse in Montreal (Quebec) found the incidence slightly higher among Haitians than French-Canadians. Among Haitians, reporting tended to originate with police or school personnel, and cases consisted mainly of physical abuse. Results suggest that child-rearing practices of Haitian families are in conflict with…

  9. Genese des Microstructures et Consequences sur les Proprietes Mecaniques dans les Polymeres Semi-Cristallins Renforces par des Charges Lamellaires

    OpenAIRE

    Vermogen , Alexandre

    2006-01-01

    This work is devoted to the development of new materials based on polymer semi-cristalline matrix (PA, PE) for packaging application. Among the possibilities to improve the barrier and the mechanical properties of semi-cristalline the use of nanometer size lamellar shape particles, such as montmorillonite, is certainly the most interesting one. The main advantages of montmorillonite are its low cost, a great potential specific area (700m2/g), a high aspect ratio (100) and good swelling proper...

  10. Reliability in mechanics: the application of experience feedback; La fiabilite en mecanique: mise en pratique du retour d`experience

    Energy Technology Data Exchange (ETDEWEB)

    Coudray, R.

    1994-12-31

    After a short overview of the available methods for statistical multi-dimensional studies, an application of these methods is described using the experience feedback of French nuclear reactors. The material studied is the RCV (chemical and volumetric control system) pump of the 900 MW PWR type reactors for which data used in the study are explained. The aim of the study is to show the pertinency of the rate of failures as an indicator of the material aging. This aging is illustrated by the most significant characteristics with an indication of their significance level. The method used combines the results from a mixed classification and those from a multiple correspondences analysis in several steps or evolutions. (J.S.). 8 refs., 6 figs., 3 tabs.

  11. Thermo-hydro-mechanical behaviour of Boom clay; Comportement thermo-hydro-mecanique de l'argile de Boom

    Energy Technology Data Exchange (ETDEWEB)

    Le, T.T

    2008-01-15

    This thesis studied the thermo-hydro-mechanical properties of Boom clay, which was chosen to be the host material for the radioactive waste disposal in Mol, Belgium. Firstly, the research was concentrated on the soil water retention properties and the hydro-mechanical coupling by carrying out axial compression tests with suction monitoring. The results obtained permitted elaborating a rational experimental procedure for triaxial tests. Secondly, the systems for high pressure triaxial test at controlled temperature were developed to carry out compression, heating, and shearing tests at different temperatures. The obtained results showed clear visco-elasto-plastic behaviour of the soil. This behaviour was modelled by extending the thermo-elasto-plastic model of Cui et al. (2000) to creep effect. (author)

  12. Development op finite volume methods for fluid dynamics; Developpement de methodes de volumes finis pour la mecanique des fluides

    Energy Technology Data Exchange (ETDEWEB)

    Delcourte, S

    2007-09-15

    We aim to develop a finite volume method which applies to a greater class of meshes than other finite volume methods, restricted by orthogonality constraints. We build discrete differential operators over the three staggered tessellations needed for the construction of the method. These operators verify some analogous properties to those of the continuous operators. At first, the method is applied to the Div-Curl problem, which can be viewed as a building block of the Stokes problem. Then, the Stokes problem is dealt with with various boundary conditions. It is well known that when the computational domain is polygonal and non-convex, the order of convergence of numerical methods is deteriorated. Consequently, we have studied how an appropriate local refinement is able to restore the optimal order of convergence for the Laplacian problem. At last, we have discretized the non-linear Navier-Stokes problem, using the rotational formulation of the convection term, associated to the Bernoulli pressure. With an iterative algorithm, we are led to solve a saddle-point problem at each iteration. We give a particular interest to this linear problem by testing some pre-conditioners issued from finite elements, which we adapt to our method. Each problem is illustrated by numerical results on arbitrary meshes, such as strongly non-conforming meshes. (author)

  13. Electro-chemo-hydro-mechanical coupling in clayey media; Couplage electro-chimio-hydro-mecaniques dans les milieux argileux

    Energy Technology Data Exchange (ETDEWEB)

    Lemaire, Th

    2004-12-15

    The aim of this study is to understand coupled phenomena that occur in swelling porous materials like clays. Electro-chemo-hydro-mechanical contributions are taken into account to analyze transfers in such minerals. In a first part, a general discussion is proposed to introduce mineralogical and physico- chemical considerations of clayey media. An important objective of this chapter is to show the crucial role of the microstructure. In a second part is presented an imbibition test in a MX80 bentonite powder. The hydraulic diffusivity versus water content curve's decrease is explained thanks to a double porosity model that shows the progressive collapse of meso-pores due to swelling effects at the micro-scale. Thus a multi-scale analysis is necessary to well describe clayey media behaviour. The third chapter exposes such a multi-scale modelling (periodic homogenization). It is based on the double-layer theory and introduces an innovative concept of virtual electrolyte solution. First numerical results are given in a simple geometry (parallel platelets). In the next part are proposed numerical simulations of two kinds: response of the system to a chemical gradient and simulation of electro-osmosis. The end of this chapter puts into relief the necessity to integrate pH effects in the model. In the last part, chemical surface exchanges are incorporated in the modelling to understand pH and ionic force roles in electro-osmotic process. (author)

  14. Contribution to the study of internal friction in graphites; Contribution a l'etude du frottement interieur des graphites

    Energy Technology Data Exchange (ETDEWEB)

    Merlin, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-03-01

    A study has been made of the internal friction in different graphites between -180 C and +500 C using a torsion pendulum; the graphites had been previously treated thermo-mechanically, by neutron irradiation and subjected to partial annealings. It has been shown that there occurs: a hysteretic type dissipation of energy, connected with interactions between dislocations and other defects in the matrix; a dissipation having a partially hysteretic character which can be interpreted by a Granato-Luke type formalism and which is connected with the presence of an 'ultra-micro porosity'; a dissipation by a relaxation mechanism after a small dose of irradiation; this is attributed to the reorientation of bi-interstitials; a dissipation having the characteristics of a solid state transformation, this during an annealing after irradiation. It is attributed to the reorganization of interstitial defects. Some information has thus been obtained concerning graphites, in particular: their behaviour at low mechanical stresses, the nature of irradiation defects and their behaviour during annealing, the structural changes occurring during graphitization, the relationship between internal friction and macroscopic mechanical properties. (author) [French] L'etude du coefficient de frottement interieur au moyen d'un pendule de torsion entre -180 C et +500 C a ete realisee pour differents graphites apres des traitements thermo-mecaniques, des irradiations neutroniques et des guerisons partielles. Il a ete mis en evidence: une dissipation d'energie a caractere hysteretique, reliee aux interactions des dislocations avec les autres defauts de la matrice; une dissipation a caractere partiellement hysteretique, interpretable par un formalisme type Granato-Lucke et reliee a la presence d'une ''ultra-microporosite''; une dissipation par un mecanisme de relaxation, apres irradiation a faible dose, attribuee a la reorientation de di-interstitiels; une dissipation presentant les caracteristiques d

  15. Recover the story of a component or the determination of the welding residual stresses; Parcourir l`histoire d`un composant ou la determination des contraintes residuelles de soudage

    Energy Technology Data Exchange (ETDEWEB)

    Genette, P. [Electricite de France (EDF), 69 - Villeurbanne (France). Service Etudes et Projets Thermiques et Nucleaires; Dupas, Ph. [Electricite de France, 77 - Moret sur Loing (France). Dept. Mecanique et Technologie des Composants; Waeckel, F. [Electricite de France (EDF), 92 - Clamart (France). Dept. Mecanique et Modeles Numerique

    1998-10-01

    Mechanical components in nuclear power plants can keep track of the welding processes they had undergone before to entrying into service. The memory of these past events can postpone or enhance possible damage phenomena on these components. Nowadays, numerical simulation software, such as the Code ASTER, enable to reproduce numerically these welding processes so that their mechanical consequences be retrieved. (authors)

  16. Design of an experiment to measure the decay heat of an irradiated PWR fuel: MERCI experiment; Conception d'une experience de mesure de la puissance residuelle d'un combustible irradie: l'experience MERCI

    Energy Technology Data Exchange (ETDEWEB)

    Bourganel, St

    2002-11-01

    After a reactor shutdown, a significant quantity of energy known as 'decay heat' continues to be generated from the irradiated fuel. This heat source is due to the disintegration energy of fission products and actinides. Decay heat determination of an irradiated fuel is of the utmost importance for safety analysis as the design cooling systems, spent fuel transport, or handling. Furthermore, the uncertainty on decay heat has a straight economic impact. The unloading fuel spent time is an example. The purpose of MERCI experiment (irradiated fuel decay heat measurement) consists in qualifying computer codes, particularly the DARWIN code system developed by the CEA in relation to industrial organizations, as EDF, FRAMATOME and COGEMA. To achieve this goal, a UOX fuel is irradiated in the vicinity of the OSIRIS research reactor, and then the decay heat is measured by using a calorimeter. The objective is to reduce the decay heat uncertainties from 8% to 3 or 4% at short cooling times. A full simulation on computer of the MERCI experiment has been achieved: fuel irradiation analysis is performed using transport code TRIPOLI4 and evolution code DARWIN/PEPIN2, and heat transfer with CASTEM2000 code. The results obtained are used for the design of this experiment. Moreover, we propose a calibration procedure decreasing the influence of uncertainty measurements and an interpretation method of the experimental results and evaluation of associated uncertainties. (author)

  17. Evaluation of residual stresses in composite materials by using neutron diffraction; study of elasto-plasticity; Etude des composites a matrice metallique par la technique de la diffraction de neutrons: analyse du comportement elastoplastique et evaluation des contraintes residuelles

    Energy Technology Data Exchange (ETDEWEB)

    Levy-Tubiana, R

    1999-11-05

    This work deals with the study of Metal Matrix Composites (MMC) using neutrons diffraction method and the analysis of the elastoplastic behavior in such materials. First, we evaluated macro-stresses in aluminium MMC reinforced with 17%vol. of SiC particles. One of the analyzed sample has been 4 point bending deformed, measurements have been performed after relaxation. The difference between the coefficients of thermal expansion constrains the matrix to be in tensile state and the particles in compressive state in the sample which has not be deformed. In the sample deformed, the MMC response is predicted by the science of Resistance Materials applied to a bent bar. We assume that macro-stresses are the sum of stresses with different origins (elastic, plastic, thermal mismatch): elastic mismatch is evaluated by Eshelby model and we determined micro-stresses in the unbent bar: they are equivalent and constant along width direction. For the bent bar, we observe relaxation of thermal stresses in the surface region. Theses results are confirmed by measurements of tensile/compressive sample using neutrons diffraction method. We also observed the influence of mechanical and thermal treatment on such MMC: the shear stress (established by the auto-coherent model) depends only on the way of cooling. Finally, a study was performed on titanium MMC for SNECMA on rotor beings used in the gas turbine engine industry. Evolution of stresses between felloe and boring is confirmed by a finite elements modeling and they are the first experimental results in this application. (author)

  18. Influence of the residual stresses on crack initiation in brittle materials and structures; Prise en compte des contraintes residuelles dans un critere d'amorcage en rupture fragile

    Energy Technology Data Exchange (ETDEWEB)

    Henninger, C

    2007-11-15

    Many material assemblies subjected to thermo-mechanical loadings develop thermal residual stresses which modify crack onset conditions. Besides if one of the components has a plastic behaviour, plastic residual deformations may also have a contribution. One of the issues in brittle fracture mechanics is to predict crack onset without any pre-existing defect. Leguillon proposed an onset criterion based on both a Griffth-like energetic condition and a maximum stress criterion. The analysis uses matched asymptotics and the theory of singularity. The good fit between the model and experimental measurements led on homogeneous isotropic materials under pure mechanical loading incited us to take into account residual stresses in the criterion. The comparison between the modified criterion and the experimental measurements carried out on an aluminum/epoxy assembly proves to be satisfying concerning the prediction of failure of the interface between the two components. Besides, it allows, through inversion, identifying the fracture properties of this interface. The modified criterion is also applied to the delamination of the tile/structure interface in the plasma facing components of the Tore Supra tokamak. Indeed thermal and plastic residual stresses appear in the metallic part of these coating tiles. (author)

  19. Design of an experiment to measure the decay heat of an irradiated PWR fuel: MERCI experiment; Conception d'une experience de mesure de la puissance residuelle d'un combustible irradie: l'experience MERCI

    Energy Technology Data Exchange (ETDEWEB)

    Bourganel, St

    2002-11-01

    After a reactor shutdown, a significant quantity of energy known as 'decay heat' continues to be generated from the irradiated fuel. This heat source is due to the disintegration energy of fission products and actinides. Decay heat determination of an irradiated fuel is of the utmost importance for safety analysis as the design cooling systems, spent fuel transport, or handling. Furthermore, the uncertainty on decay heat has a straight economic impact. The unloading fuel spent time is an example. The purpose of MERCI experiment (irradiated fuel decay heat measurement) consists in qualifying computer codes, particularly the DARWIN code system developed by the CEA in relation to industrial organizations, as EDF, FRAMATOME and COGEMA. To achieve this goal, a UOX fuel is irradiated in the vicinity of the OSIRIS research reactor, and then the decay heat is measured by using a calorimeter. The objective is to reduce the decay heat uncertainties from 8% to 3 or 4% at short cooling times. A full simulation on computer of the MERCI experiment has been achieved: fuel irradiation analysis is performed using transport code TRIPOLI4 and evolution code DARWIN/PEPIN2, and heat transfer with CASTEM2000 code. The results obtained are used for the design of this experiment. Moreover, we propose a calibration procedure decreasing the influence of uncertainty measurements and an interpretation method of the experimental results and evaluation of associated uncertainties. (author)

  20. Livingston-Courant magnetic lens and their use in focussing a beam supplied by a Van der Graaff; Lentilles magnetiques Courant-Livingston et leur utilisation a la focalisation du faisceau donne par un Van de Graaff

    Energy Technology Data Exchange (ETDEWEB)

    Gendreau, G.

    1953-11-15

    This technical note presents the general calculation of focal distances of a system made of two crossed thick lens. It outlines that these lens can be considered as thin lens in their operation domain (focal distance comprised between an element length and the infinite), and then elaborated formula for all optical elements. These formula are then applied to lens built for the Van der Graaff. The actual length of a lens is then given with respect to its theoretical length. Obtained numerical values lead to the determination of magnetic and mechanical characteristics of a lens [French] Le calcul general des distances focales d'un systeme de deux lentilles epaisses croisees est explicite. Dans leur domaine d'utilisation (distances focales comprises entre l'infini et la longueur d'un element) on peut les considerer comme minces, tous les elements optiques sont alors formules. L'application de ces formules aux lentilles construites pour le Van de Graaff se traduit par les tableaux I et II. On donne la longueur reelle d'une lentille en fonction de sa longueur theorique. Les valeurs numeriques trouvees conduisent a la determination des caracteristiques magnetiques et mecaniques d'une lentille. (auteur)

  1. Conditioning of solid radioactive wastes (1960); Conditionnement des dechets radioactifs solides (1960)

    Energy Technology Data Exchange (ETDEWEB)

    Cerre, P [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    Since solid radioactive wastes are of varied forms, dimensions and volumes, the C.E.A. first reduces the volume by breaking up and compacting. Since these wastes cannot be temporarily stored without contamination risk, an effective packing process has been devised and carried through. This consists in burying the wastes in a specially planned concrete with the following characteristics: - high mechanical resistance; - maximum insolubility; - resistance to corrosion; - maximum imperviousness; - providing protection against radiation. It is then possible to store the blocks safely, with a view to eventual definitive rejection. (author) [French] Les dechets actifs solides etant de formes, de dimensions et de volumes varies, le C.E.A. procede en premier lieu a une reduction de volume par fractionnement et compactage. L'emmagasinage provisoire de tels dechets ne pouvant se concevoir sans risques de contamination, un procede efficace d'emballage a ete etudie et realise. Il consiste a noyer les dechets dans un beton specialement etudie qui presente les caracteristiques suivantes: - forte resistance mecanique; - insolubilite maximum; - resistance a la corrosion; - etancheite maximum; - protection contre le rayonnement. Il est alors possible de conserver sans danger les blocs formes en vue d'un rejet definitif ulterieur. (auteur)

  2. Diffused zircaloy 2/stainless steel junctions; Jonctions diffusees zircaloy 2 - acier inoxydable

    Energy Technology Data Exchange (ETDEWEB)

    Jacques, F [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    The diffusion permits to realize joints between two different materials, in fact of the formation of a liquid phase at the contact face. The study of the tensile properties allowed the determination of the ideal conditions for the diffusion treatment which are, within 2 and 3 minutes for a temperature within 1020 C and 1030 C. The characteristics of the so obtained joints were, studied: mechanical properties, tightness, resistance to thermal cycling. Analysis of the thermal stress, owing to the differential dilatation of the two materials mode the object of a particular study. The investigation on the diffusion zone, includes specially, an analysis of the constituents distribution formed during the diffusion treatment. (author) [French] La diffusion permet de realiser des joints entre deux materiaux differents, du fait de la formation d'une phase liquide a l'interface de contact. L'etude de la resistance a la traction a permis de determiner les conditions optimum du traitement de diffusion: une duree de 2 a 3 minutes pour une temperature comprise entre 1020 C et 1030 C. Les caracteristiques des jonctions ainsi obtenues ont ete etudiees: proprietes mecaniques, etancheite, resistance au cyclage thermique. L'analyse des contraintes thermiques dues a la difference de dilatation des deux materiaux, a fait l'objet d'une etude particuliere. L'etude metallurgique de la zone diffusee comporte en particulier une analyse de la repartition des constituants formes lors du traitement de diffusion. (auteur)

  3. Caracteristiques de trois systemes informatiques de transcription phonetique et graphemique (Characteristics of Three Computer-Based Systems of Phonetic and Graphemic Transcription).

    Science.gov (United States)

    Marty, Fernand

    Three computer-based systems for phonetic/graphemic transcription of language are described, compared, and contrasted. The text is entirely in French, with examples given from the French language. The three approaches to transcription are: (1) text entered in standard typography and exiting in phonetic transcription with markers for rhythmic…

  4. RECRUTEMENT DES CIVELLES (ANGUILLA ANGUILLA SUR LA COTE MEDITERRANEENNE FRANÇAISE : ANALYSE COMPAREE DES CARACTERISTIQUES BIOMETRIQUES ET PIGMENTAIRES DES SAISONS 1974-75 ET 2000-01.

    Directory of Open Access Journals (Sweden)

    LEFEBVRE F.

    2003-07-01

    Full Text Available Une campagne d’échantillonnage des civelles Anguilla anguilla a été menée de novembre 2000 à mai 2001 au grau de la Fourcade (Saintes-Maries-de-la-Mer, côte méditerranéenne française. Des civelles ont été capturées sur toute la période d’échantillonnage, mais les maxima d’abondance se situent en janvier-février et, dans une moindre mesure, en avril. Afin d’optimiser le recrutement dans les lagunes littorales intérieures, la mesure de gestion proposée est donc de favoriser l’ouverture des martelières au milieu de l’hiver. Le suivi des proportions mensuelles des différents stades pigmentaires (de V A à VI A4 permet de conclure à un vieillissement généralisé des civelles en recrutement de novembre à mars, puis à l’arrivée d’un deuxième flux de civelles jeunes en avril. Parallèlement, il est observé une diminution très nette des masses et des longueurs moyennes mensuelles, et ce, même en ne considérant qu’un stade pigmentaire donné (en l’occurrence V B. Ces résultats sur l’évolution des caractéristiques biométriques et pigmentaires sont en accord avec les deux séries de travaux déjà menés sur la façade méditerranéenne française (années 30 et 70, ainsi qu’avec les données publiées en différents points de la façade atlantique. L’analyse comparée de ces données avec celles issues de la dernière étude en date sur la côte méditerranéenne française (Bages-Sigean, Languedoc-Roussillon, campagne 1974-75 ; LECOMTE-FINIGER, 1976 montre une composition pigmentaire mensuelle totalement différente, et révèle une diminution significative de la longueur des civelles, de l’ordre de 5 % en 25 ans.

  5. New solutions in the use of energy. Characteristics for a Mediterranean building; Nouvelles solutions dans l'utilisation de l'energie. Caracteristiques pour un batiment mediterraneen

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-07-01

    This document is edited by the regional energy agency of Provence-Alpes-Cote d'Azur region (ARENE) with the participation of the ICAEN (Institut Catala d'Energia) (Barcelona, Spain) and Punto Energia (Milan, Italy) and with the help of the general direction of energy of the European Commission (DG 17, sub-program 'Energy'). It presents the rules for the elaboration of a 'building program' devoted to foremen and which aims at integrating the energy and environmental requirements of a building prior to its construction: 1 - planning (goal, preliminary and feasibility studies); 2 - elaboration of the energy program (environmental context of the project, demand formulation: environmental impact, comfort, electricity and water uses, maintenance, costs..); 3 - characteristics of a Mediterranean building (regional aspect, envelope and passive heating/cooling techniques, active techniques), 4 - energy feasibility study; 5 - evaluation means. (J.S.)

  6. Influence de l'alteration physique sur les caracteristiques physico-chimiques de monolithes de sols contamines traites par stabilisation/solidification au ciment

    Science.gov (United States)

    Remillard, Jonathan

    The concern of contaminated sites is affecting millions of property owner worldwide. As they pose a risk to the environment, human health or impair the value of buildings, remediation of contaminated sites has become an everyday issue. Stabilization/solidification (S/S) of contaminated soils with cement is a remediation technology that was developed to confine contaminants that cannot be degraded biologically, chemically or thermally by other technologies. Soils treated with S/S form a monolith that can be valorized on site. However, this practice is fairly uncommon in Quebec and this reluctance is partly due to the risks of degradation of the monoliths and the lack of knowledge relative to the long-term behavior of altered monoliths. The objective of this project was to simulate these degradations on cement-based monoliths of contaminated soils treated with S/S technology by causing physical alterations using different cycles of freeze/thawing and drying/wetting, and then to study the impact of these alterations on the mass losses, compressive strength, hydraulic conductivity, pH and leachability of five trace metals (Cd, Cr, Cu, Pb and Zn) used as contaminants. Various processes of S/S have been studied, either cement contents of 15 and 20%, then the presence of 5% by weight of calcium carbonate. For each S/S process formulated, the freeze/thaw cycles were much more effective in physically altering the monoliths. These alterations were mainly reflected by lower compressive strength, even more with lower cement contents. For their part, the drying/wetting cycles rather created a chemical change that lowered the pH of the monoliths. These chemical changes also affected the interpretation of leaching test results, especially for copper and zinc, since it was difficult to attribute effects to either physical or chemical alterations. The results showed that only chromium leached more clearly in response to physical alterations. All other elements studied were little affected, even though some samples were highly altered. This demonstrates that in some cases, damages may have little impact on long-term performance of the monoliths in terms of contaminant immobilization. However, integrating the study of long-term behaviors of monoliths in a process of formulation for contaminated soil treatment with S/S can become paramount, as seen for chromium in this present study. Keywords: stabilization / solidification, deterioration, alteration, leachability, contaminants.

  7. What is Essential for Virtual Reality Systems to Meet Human Performance Goals? (les Caracteristiques essentielles des systemes VR pour atteindre les objectifs militaires en matiere de performances humaines)

    Science.gov (United States)

    2001-03-01

    training world will be digital cinema, the convergence of television with the World Wide Web, and the continued rapid growth of multiplayer Internet...innocent civilians from being hurt in factional violence while preventing, as much as possible, new flare ups among the factions. By sharing an immersive

  8. Effects of hydrogen on the tensile strength characteristics of stainless steels; Effets de l'hydrogene sur les caracteristiques de rupture par traction d'aciers inoxydables

    Energy Technology Data Exchange (ETDEWEB)

    Blanchard, R; Pelissier, J; Pluchery, M [Commissariat a l' Energie Atomique, Grenoble (France).Centre d' Etudes Nucleaires; Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1961-07-01

    This paper deals with the effects of hydrogen on stainless steel, that might possibly be used as a canning material in hydrogen-cooled reactors. Apparent ultimate-tensile strength is only 80 per cent of initial value for hydrogen content about 50 cc NTP/ 100 g, and reduction in area decreases from 80 to 55 per cent. A special two-stage replica technique has been developed which allows fracture surface of small tensile specimens (about 0.1 mm diam.) to be examined in an electron microscope. All the specimens showed evidence of ductile character throughout the range of hydrogen contents investigated, but the aspect of the fracture surfaces gradually changes with increasing amounts. (author) [French] On etudie les effets de l'hydrogene sur des aciers inoxydables, qui sont des materiaux de gainage possibles pour des reacteurs utilisant l'hydrogene comme gaz de refroidissement. On montre que la charge apparente de rupture a la traction n'est plus que 80 pour cent de sa valeur initiale lorsque la teneur en hydrogene atteint 50 cc TPN/ 100 g, et que la striction passe dans ces conditions de 80 a 55 pour cent. L'examen microfractographique qui a ete effectue avec succes par une technique de double replique malgre la petitesse des echantillons (0,3 mm de diametre environ), revele que tout en gardant un caractere ductile, l'aspect des surfaces de rupture evolue notablement avec la teneur en hydrogene. (auteur)

  9. Fast spin echo MRI techniques. Contrast characteristics and clinical potential. Techniques d'IRM en fast spin echo. Caracteristiques de contraste et potentiels cliniques

    Energy Technology Data Exchange (ETDEWEB)

    Melki, P.; Mulkern, R.V.; Dacher, J.N.; Helenon, O.; Higuchi, N. (Harvard Medical School, Boston, MA (United States)); Oshio, K.; Jolesz, F. (Keio Univ., Tokyo (Japan)); Pourcelot, L. (Hopital Bretonneau, 37 - Tours (France)); Einstein, S. (General Electric Medical System, Milwaukee, WI (United States))

    1993-03-01

    Based on partial RF echo planar principles, Fast Spin Echo techniques (FSE) were implemented on high field systems. These methods produce image quality and contrast which resemble to conventional spin echo (SE) techniques. By reducing acquisition times by factors between 1.4 and 16 over SE methods, FSE allows for several imaging options usually prohibitive with conventional spin echo (SE) sequences. These include fast scans (especially breathold acquisitions); improved T2 contrast with longer TR intervals; increased spatial resolution with the use of larger image matrices and/or smaller fields of view; and 3D volume imaging with a 3D multislab FSE technique. Contrast features of FSE techniques are directly comparable to those of multiple echo SE sequences using the same echo spacing than FSE methods. However, essential contrast differences existing between the FSE sequences and their routine asymmetric dual SE counterpart can be identified. Decreased magnetic susceptibility effects and increased fat signal present within T2 weighted images compared to conventional dual SE images are due to the use of shorter echo spacings employed in FSE sequences. Off-resonance irradiation inherent to the use of a large number of radio frequency pulses in shown to results in dramatic magnetization contrast transfer effects in FSE images acquired in multislice mode.

  10. Chemical and microbiological characteristics of Lebanese cheeses made by local industries; Caracteristiques chimiques et microbiologiques des fromages libanais issus d'industries locales

    Energy Technology Data Exchange (ETDEWEB)

    Dib, H.; Hajj Semaan, E.; Noureddine, Z. [Lebanese University, Faculty of Agronomy, Dekwaneh (Lebanon)

    2008-07-01

    In order to characterize, protect dairy products and develop new probiotics, a survey was conducted amongst 37 dairy factories. Chemical (pH, acidity, DM, protein, fat, soluble nitrogen and free fatty acid) and microbiological (total aerobic bacteria, Coliforms, E. coli, Salmonella, Listeria, and Staphylococcus aureus) analysis were carried out on samples collected from factories (7 Baladi, 22 Akkawi, 18 Double creme and 22 Halloum) of different regions. These cheeses are made by 73% of visited factories. Chemical analysis showed low acidity (0.18 to 0.26%), variable levels of moisture (54 to 70%) protein (19 to 24%) and fat (12 to 18%) except Double creme (3.26 {+-} 1.78%). Except 8%, Good Hygienic and Manufacturing Practices (GHP/GMP) are not applied in visited factories. This is confirmed with the high levels of Coliforms, detectable in most varieties at an alarming level (72 to 86%). Besides, 23-71% of samples were contaminated with E. coli. However, all samples were found free of staphylococcus aureus; Halloum cheese was the only one free of Listeria and Salmonella. The highest off standard for these bacteria was noticed in Baladi cheese where 29% were contaminated with Listeria and Salmonella. Listeria was also found in 10% of Akkawi and 17% of Double creme. These results show a violation of the Good Hygienic and Manufacturing Practices (GHP/GMP) by most factories in all visited regions. (author)

  11. The Proportional Counter. Some Aspects of Operation; Le compteur proportionnel. Ses caracteristiques de fonctionnement; Proportsional'nyj schetchik. Nekotorye aspekty raboty; El contador proportional. Sus caracteristicas de funcionamiento

    Energy Technology Data Exchange (ETDEWEB)

    Curran, S C [Awre, Aldermaston (United Kingdom)

    1960-06-15

    1. Work on a counter system designed for electron capture studies has shown that the diameter of the anode wire in a high-pressure proportional counter can have an important influence on the energy resolution obtained in measurements of low-energy radiations. In a counter working at a pressure of 12 atmospheres the width of the pulse distribution due to 13.5 keV K-capture radiations could be changed from 65% to 17% by changing the wire diameter from 0.0076 mm to 0.0025 mm. This phenomenon is interpreted as an effect of positive ion space charge in the avalanche. For a given gas gain and primary radiation the density of positive ions in the avalanche increases rapidly with pressure of the filling gas, and when the accompanying electric fields are large enough to affect the last stages of the multiplication process the energy resolution of the counter deteriorates. Decrease in diameter of the anode wire increases the externally applied field in the region where multiplication takes place, thus tending to counteract the effect of space charge. Use of 0.0025 mm anode wires has proved satisfactory in new measurements of L/K capture ratios made with a multiwire counter system working at pressures up to 12 atmospheres. The results obtained for L/K capture ratios of Ge{sup 71} and Kr{sup 79} are 0.115 and 0.112 respectively. The same counting system has also been used in a search for M capture in these two isotopes. The low energy of the M capture radiation, 180 eV in Ge{sup 71} and 260 eV in Kr{sup 79}, and its low intensity relative to that of K capture, makes accurate measurement difficult; but peaks attributable to M capture were observed in pulse spectra of both sources. 2. Low-Background Counting - Recent observations made on a combination of proportional counter and scintillation counters (operating as shields) show that there are some real difficulties in devising a relatively simple system of this kind. The performance is inherently very satisfactory but practical matters such as long-term gas purity are difficult to overcome. 3. Studies of Electron Attachment - An approach to systematic observations in gases and mixtures of moment in proportional counting is described. It is hoped that such measurements as are effected with this arrangement will be valuable in enlarging the field of application of the counters. (author) [French] 1. Les travaux consacres a la mise au point d'un dispositif de comptage destine a l'etude de la capture electronique ont montre que le diametre du, fil constituant l'anode dans un compteur proportionnel a haute pression peut avoir une influence importante sur le pouvoir de resolution en energie obtenu dans les mesures de rayonnements de faible energie. Dans un compteur travaillant sous une pression de 12 atmospheres, l'amplitude de la repartition des impulsions dues aux rayonnements de capture K de 13,5 keV a pu etre ramenee de 65% a 17%. en reduisant de 0,0076 mm a 0,0025 mm le diametre du fil. Ce phenomene est interprete comme constituant un effet de la charge spatiale en ions positifs dans l'avalanche. Pour un gain et un rayonnement primaire donnes, la densite des ions positifs dans l'avalanche s'accroit rapidement avec la pression du gaz de remplissage, et lorsque les champs electriques d'accompagnement sont assez grands pour affecter les derniers stades du processus de multiplication, le pouvoir de resolution en energie du compteur diminue. Toute diminution du diametre de l'anode entraine un accroissement du champ applique exterieurement, dans la region ou se produit la multiplication, ce qui tend a contrecarrer l'effet de la charge spatiale. L'emploi de fils d'un diametre de 0,0025 mm a donne des resultats satisfaisants lors de nouvelles mesures des rapports de capture L/K effectuees au moyen d'un dispositif de comptage a fils multiples, travaillant sous des pressions pouvant atteindre 12 atmospheres. Les resultats obtenus pour les rapports de capture L/K du Ge{sup 71} et du Kr{sup 79} sont de 0,115 et 0,112 respectivement. On a utilise le meme dispositif de comptage pour etudier la capture M dans ces deux isotopes. La faible energie du rayonne- ment de capture M, soit 180 eV pour le Ge{sup 71} et 260 eV pour le Kr79, ainsi que sa faible intensite comparee a celle de la capture K, rendent difficiles les mesures precises; cependant, des pics imputables a la capture M ont ete observes dans les spectres d'impulsions des deux sources. 2. Comptage d'une activite de fond peu elevee - Des observations recentes faites avec un dispositif comprenant un compteur proportionnel et des compteurs a scintillateurs (ces derniers agissant comme ecrans protecteurs) montrent que la mise au point d'un dispositif relativement simple de ce genre presente de serieuses difficultes. Le fonctionnement est tres satisfaisant en soi, mais certains problemes pratiques, tels que le maintien d'un gaz a l'etat pur pendant une longue periode, sont difficiles a resoudre. 3. Etudes sur l'accumulation d'electrons - On decrit une methode d'observation systematique portant sur les gaz et melanges importants pour le comptage proportionnel. On espere que les mesures effectuees grace au dispositif correspondant s'avereront utiles en permettant d'elargir le champ d'application des compteurs. (author) [Spanish] 1. Los trabajos de perfeccionamient o de un dispositivo de recuento destinado al estudio de la captura electronica demuestran que el diametro del alambre anodico de un contador proporcional de elevada presion puede ejercer una influencia considerable sobre el poder de resolucion energetica obtenido en la medicion de radiaciones de baja energia. En un contador que trabaje a la presion de 12 atmosferas, la amplitud de la distribucion de los impulsos debidos a radiaciones de captura K de 13,5 keV, puede reducirse de 65 a 17% sustituyendo el alambre de 0,0076 mm de diametro por otro de 0,0025 mm. Este fenomeno se interpreta como un efecto de la carga espacial de los iones positivos en la avalancha. Para una amplificacion gaseosa y una radiacion pri- maria determinadas, la densidad de los iones positivos en la avalancha aumenta rapidamente con la presion del gas contenido en el contador, y cuando los campos electricos concomitantes tienen suficiente intensidad para afectar las ultimas fases del proceso de multiplicacion, el poder de resolucion del contador disminuye. La reduccion del diametro del alambre anodico trae aparejado un aumento de la intensidad del campo externo en la zona donde se verifica la multiplicacion, tendiendo asi a contrarrestar el efecto de la carga espacial, pero el empleo de alambres anodicos de 0,0025 mm ha dado resultados satisfactorios en nuevas mediciones de las razones de captura L/K efectuadas con un contador de hilos multiples funcionando a presiones de hasta 12 atmosferas. Los resul- tados obtenidos para la razon de captura L/K del Ge{sup 71} y del Kr{sup 79} son 0,115 y 0,112 respectivamente . El mismo sistema de recuento se ha empleado para investigar una posible captura M en estos dos isotopos. La baja energia de la radiacion emitida por captura M, a saber 180 eV en el Ge{sup 71} y 260 eV en el Kr{sup 79}, asi como su reducida intensidad en relacion con la correspondiente a la captura K, dificultan una medicion exacta; sin embargo, en los espectros de impulsos de ambas fuentes se han observado maximos que pueden atribuirse a la captura M. 2. Recuento de bajas actividades de fondo. - Observaciones recientes efectuadas con un dispositivo formado por un contador proporcional y contadores de centelleo (que funcionan como pantalla protectora) revelan que la construccion de un dispositivo relativamente sencillo de este tipo ofrece ciertas dificultades. El funcionamiento es de por si muy satisfactorio, pero algunos problemas practicos, tales como el mantenimiento del gas al estado puro durante uen tiempo largo, son dificiles de resolver. 3. Estudios sobre acumulacion de electrones. - El autor describe un procedimiento de observacion sistematica de las propriedades de los gases y mezclas utilizadas en el recuento proporcional. Cabe esperar que las mediciones efectuadas con este dispositivo permitan ampliar el campo de aplicacion de los contadores. (author) [Russian] I. Rabota nad schetnoj sistemoj, prednaznachenno j dlya izucheniya zakhvata ehlektronov, pokazala, chto diametr anoidnogo provoda v proportsional'no m schetchike s vysokim' davleniem mozhet okazyvat' bol'shoe vliyanie na razreshenie po ehnergii, poluchaemoe pri izmereniyakh radiatsii nizkoj ehnergii. V schetchike, rabotayushchem pri davlenii v 12 atmosfer, shirina raspredeleniya impul'sov pri radiatsii v 13,5 kehv K-zakhvata mozhet byt' izmenena ot 65% do 17% posredstvom izmeneniya diametra provoda ot 0,0076 do 0,0025 millimetra. EHto yavlenie ob{sup y}asnyaetsya kak dejstvie polozhitel'nogo prostranstvennog o zaryada iona v lavine. Dlya opredelennogo usileniya gaza i osnovnoj radiatsii plotnost' polozhitel'ny kh ionov v lavine bystro uvelichivaetsya vmeste s davleniem napolnyayushchego gaza, i kogda soputstvuyushchie ehlektricheskie polya stanovyatsya dostatochno bol'shimi, chtoby povliyat' na poslednie stadii protsessa umnozheniya, razreshenie po ehnergii schetchika ukhudshaetsya. Umen'shenie diametra anodnogo provoda uvelichivaet poyavlyayushcheesya izvne pole v tom meste, gde proiskhodit umnozhenie, i tem samym stremitsya protivodejstvovat ' dejstviyu prostranstvennogo zaryada. Ispol'zovanie 0,0025-millimetrovy kh anodnykh provodov okazalos' udovletvoritel'ny m pri novykh izmereniyakh koehffitsient a zakhvata L/K, provodimogo s mnogoprovodno j schetnoj sistemoj s Davleniem do 12 atmosfer. Rezul'taty, poluchennye dlya koehffitsienta zakhvata L/K s Ge{sup 71} i Kg{sup 79} ravny 0,115 i 0,112 sootvetstvenno . Tazhe schetnaya sistema ispol'zovalas' pri issledovanii M-zakhvata v ehtikh dvukh izotopakh. Nizkaya ehnergiya radiatsii M-zakhvata, 180 ehv v Ge{sup 71}, 260 ehv v Kg{sup 79} i ee nizkaya intensivnost' po po sravneniyu s intensivnost'yu K-zakhvata zatrudnyayut tochnoe izmerenie; no vysshie tochki blagodarya M-zakhvatu nablyudalis' v impul'snykh spektrakh oboikh istochnikov. II. Schetchik s nizkim fonom. - Poslednie nablyudeniya, provedennye na kombinatsii proportsional'nog o i stsintillyatsionnog o schetchikov (dejstvuyushchikh v kachestve ehkranov), pokazyvayut, chto imeyutsya nekotorye real'nye trudnosti v sozdanii prostoj sistemy takogo roda. Dejstvie ee v printsipe ves'ma udovletvoritel'no , no trudno razreshit' takie prakticheskie voprosy, kak dolgovremenno e sokhranenie chistoty gaza. III. Izuchenie ehlektronnogo prisposobleniya . - Opisyvaetsya podkhod k probleme sistematicheski kh nablyudenij momenta v proportsional'no m ischislenii v gazakh i smesyakh. Nadeyutsya, chto takie izmereniya, na kotorye okazyvaet vozdejstvie ehto ustrojstvo, budut polezny dlya rasshireniya predelov primeneniya schetchikov. (author)

  12. Characteristics of the plasma injected into D.E.C.A. 2; Caracteristiques du plasma injecte dans D.E.C.A. 2

    Energy Technology Data Exchange (ETDEWEB)

    Lecoustey, P; Luc, H; Tachon, J; Veron, D [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1963-07-01

    Deuterium plasma is injected from an electrode-less plasma gun along the lines of force of a static magnetic field. This field is constant over length of 1 m; it increases thereafter in a 10 to 1 ratio over a 4 meter length up to the chamber where the measurements are carried out. Density measurements are performed using Faraday cups and an 8.6 mm microwave interferometer. For instance in a 1600 G magnetic field a 0.5 x 10{sup 13} deutons/cm{sup 3} density arises for a plasma with velocity 3 x 10{sup 7} cm/s. The transverse energy is first determined from the diamagnetic signal amplitude of magnetic loops. The main results are obtained from the study of plasma transmitted through a magnetic barrier by means of measurements made with a Faraday cup, magnetic loops and thermocouples. The results given by these different methods are in good agreement and allow to define for the whole of the plasma flow a mean < {theta} > value for the ions pitch angle. In a 1600 G, < {theta} > equal 32 degrees; i.e. mean transverse energy of 360 eV for a plasma with a 030 eV longitudinal energy (a velocity equal to 3 x 10{sup 7} cm/s). The high value of the transverse energy might be attributed to a pre-compression in the field gradient. Preliminary measurements seem to indicate the possibility of trapping the plasma between two magnetic barriers. (authors) [French] Un plasma de deuterium est injecte par un canon a induction parallelement aux lignes de force d'un champ magnetique statique, constant sur une longueur de 1 m et ensuite croissant dans un rapport 10 a 1 sur une longueur de 4 m, jusque dans la chambre ou sont effectuees les mesures. La densite est determinee par des mesures d'interferometrie hertzienne et au moyen de cylindres de Faraday. Par exemple dans un champ de 1600 G on trouve une densite de 0,5 x 10{sup 13} deutons/cm{sup 3} pour un plasma anime d'une vitesse de 3 x 10{sup 7} cm/s. Une premiere determination de l'energie transversale est faite a partir des signaux diamagnetiques donnes par des boucles magnetiques. Les resultats essentiels sont obtenus a partir de l'etude de la transmission du plasma a travers une barriere magnetique au moyen de mesures faites avec un cylindre de Faraday, des boucles magnetiques et des thermocouples. Les resultats obtenus par ces differentes methodes sont tres coherents entre eux et ont permis de definir pour tout le jet de plasma une valeur moyenne < {theta} > de l'angle, entre le vecteur vitesse d'un ion et les lignes de champ. Dans un champ de 1600 G on trouve < {theta} > = 32 degres, soit une energie transversale moyenne de 360 eV pour un plasma ayant une energie longitudinale de 930 eV (vitesse 3 x 10{sup 7} cm/s). La valeur elevee de l'energie transversale pourrait etre attribuee a une pre-compression dans le gradient de champ. Des mesures preliminaires semblent mettre en evidence la possibilite de capturer le plasma entre deux barrieres magnetiques. (auteurs)

  13. Oxidation of sulphite to sulphate in presence of protohematin - 1. general characteristics (1961); Oxydation du sulfite en sulfate en presence de protohematine - 1. caracteristiques generales (1961)

    Energy Technology Data Exchange (ETDEWEB)

    Fromageot, P; Chapeville, F [Commissariat a l' Energie Atomique, Dept. de Biologie, Saclay (France). Centre d' Etudes Nucleaires

    1961-07-01

    Protohematin catalyzes the oxidation of sulphite. The optimum pH of the reaction is approximately 7 in the presence of a 0.05 M phosphate buffer. The oxidation of sulphite is not coupled to the reduction of protohematin to protohaem. Reagents able to form complexes with the iron of protohematin are inhibitors of its catalytic function. (authors) [French] La protohematine possede la propriete de catalyser l'oxydation du sulfite. Le pH optimum de cette reaction est voisin de 7 en presence d'un tampon phosphate 0,05 M. L'oxydation du sulfite n'est pas liee a la reduction de la protohematine en protoheme et les substances susceptibles de former des complexes avec le fer de la protohematine sont des inhibiteurs de son action catalytique. (auteurs)

  14. G2 - G3 inventive properties, the first french nuclear plants; Caracteristiques generales et aspects originaux des reacteurs G2 et G3

    Energy Technology Data Exchange (ETDEWEB)

    Pascal,; Horowitz,; Bussac,; Joatton,; de Meux, De Lagge; Martin, [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1958-07-01

    This paper points out the inventive properties of the frenchctors G2 and G3. These are dual purpose reactors, i.e. designed for the production of both plutonium and energy (30 electrical MW); in this respect, they can be considered as the start point of the french electrical energy produced from nuclear fuel. The following points are specially discussed in this paper: the choice of the prestressed concrete pressure vessel, the horizontal arrangement of the channels, the interest of neutron flux flattening, the advantages of the charging and discharging device working during pile operation. (author)Fren. [French] Les caracteres originaux des reacteurs fran is G2 et G3 sont decrits dans ce rapport. Ce sont des reacteurs a double fin, plutonigenes et aussi producteurs d'energie (30 MW electriques); ils constituent a ce titre le point de depart de la production fran ise d'electricite d'origine nucleaire. Sont discutes, en particulier, dans ce rapport: le choix du caisson en beton precontraint pour tenir la pression, la disposition horizontale des canaux, l'interet de l'aplatissement du flux neutronique, les avantages de l'appareil permettant le chargement et le dechargement du combustible sans arreter la pile. (auteur)

  15. Determination of stresses in a sheath connected to a rod; Determination des contraintes dans une gaine liee a un barreau

    Energy Technology Data Exchange (ETDEWEB)

    Bernard, J L; Gauthron, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1957-07-01

    Uranium rods introduced into a pile must be protected by impermeable metal canning. Depending on the type of canning adopted, it can be assumed that in certain cases there is a longitudinally rigid connection between this tubular sheath and the rod, either along the whole length (a threaded rod for example) or only at the ends. Even unintentional points of contact, of mechanical or physico-chemical origin, can sometimes be produced accidentally. During pile operation and the resulting variable thermal cycles, the rod and the canning will tend to expand each according to its own expansion law. Given the respective surfaces of rod and canning involved in a cross-section, and the mechanical properties of the two materials considered, it can be legitimately supposed that the canned rod will follow the expansion law of uranium. It follows that the canning, always compelled to follow the expansions of the rod, will be subject to stresses and this study is aimed at their determination. (author) [French] Les barreaux d'uranium introduits dans une pile doivent etre proteges par une gaine metallique etanche. Suivant le mode de gainage adopte, on peut admettre qu'il existe dans certains cas une liaison rigide dans le sens longitudinal entre cette gaine tubulaire et le barreau, sur la totalite de leur longueur (barreau filete par exemple) ou simplement a leurs extremites. Meme s'ils n'ont pas ete provoques, des points d'accrochage, d' origine mecanique ou physico-chimique, peuvent accidentellement nous ramener parfois a ce cas. Lors du fonctionnement de la pile et des cycles thermiques variables qui en resultent, le barreau et la gaine vont tendre a se dilater chacun suivant sa loi de dilatation propre. Etant donne les sections respectives de barreau et de gaine mises en jeu dans une section droite, et les caracteristiques mecaniques des deux materiaux consideres, on peut legitimement admettre que le barreau gaine va suivre la loi de dilatation de l'uranium. Il s'ensuit que la

  16. Study methods for the drillings around the underground nuclear explosions in the Sahara. Part 1. study of rock samples; Methodes d'etude des forages realises autour des explosions nucleaires souterraines au Sahara. Premiere partie: etude des echantillons de roche

    Energy Technology Data Exchange (ETDEWEB)

    Derlich, S [Commissariat a l' Energie Atomique, Bruyers-le-Chatel (France). Centre d' Etudes

    1969-07-01

    An examination of the mechanical effects produced on rocks by an underground nuclear explosion calls for the use of particular means of exploration which are described in this report, special attention being paid to the equipment used in connection with the French nuclear tests in the Sahara. The drilling methods used (rotary and turbo-drilling) are adapted to the particular conditions of the sampling programme, to the radioactivity and to the temperature in the region of the explosion. A study of the samples makes it possible to obtain the new characteristics of the rock and to assess the chemical and mechanical transformations which it has undergone. An examination of the core obtained from the drilling, together with a knowledge of the drilling parameters (depth of the probe, sample recovery, etc...), makes it possible to study the extent and the characteristics of the zones which have been damaged to different degrees according to their distance from the zero point: cavity, strongly powdered zone, fractured zone, chimney, zones containing high stresses leading to a particular type of fracture of the cores. The problems connected with the interpretation of the results are also presented. (author) [French] L'examen des effets mecaniques provoques par une explosion nucleaire souterraine sur la roche necessite la mise en oeuvre de moyens d'exploration particuliers dont l'expose fait l'objet de ce rapport, essentiellement pour les moyens utilises autour des essais nucleaires francais au Sahara. Les methodes de forage (rotary et turboforage) sont adaptees aux conditions particulieres dues au programme d'echantillonnage, a la radioactivite et a la temperature regnant a proximite du point de tir. L'etude des echantillons permet la determination des nouveaux caracteres de la roche et de ses transformations chimique et mecanique. L'examen des carottes et l'utilisation des parametres de forage (cotes sondeurs, recuperation des echantillons, etc...) permettent d'etudier l

  17. Prediction du profil de durete de l'acier AISI 4340 traite thermiquement au laser

    Science.gov (United States)

    Maamri, Ilyes

    Les traitements thermiques de surfaces sont des procedes qui visent a conferer au coeur et a la surface des pieces mecaniques des proprietes differentes. Ils permettent d'ameliorer la resistance a l'usure et a la fatigue en durcissant les zones critiques superficielles par des apports thermiques courts et localises. Parmi les procedes qui se distinguent par leur capacite en terme de puissance surfacique, le traitement thermique de surface au laser offre des cycles thermiques rapides, localises et precis tout en limitant les risques de deformations indesirables. Les proprietes mecaniques de la zone durcie obtenue par ce procede dependent des proprietes physicochimiques du materiau a traiter et de plusieurs parametres du procede. Pour etre en mesure d'exploiter adequatement les ressources qu'offre ce procede, il est necessaire de developper des strategies permettant de controler et regler les parametres de maniere a produire avec precision les caracteristiques desirees pour la surface durcie sans recourir au classique long et couteux processus essai-erreur. L'objectif du projet consiste donc a developper des modeles pour predire le profil de durete dans le cas de traitement thermique de pieces en acier AISI 4340. Pour comprendre le comportement du procede et evaluer les effets des differents parametres sur la qualite du traitement, une etude de sensibilite a ete menee en se basant sur une planification experimentale structuree combinee a des techniques d'analyse statistiques eprouvees. Les resultats de cette etude ont permis l'identification des variables les plus pertinentes a exploiter pour la modelisation. Suite a cette analyse et dans le but d'elaborer un premier modele, deux techniques de modelisation ont ete considerees, soient la regression multiple et les reseaux de neurones. Les deux techniques ont conduit a des modeles de qualite acceptable avec une precision d'environ 90%. Pour ameliorer les performances des modeles a base de reseaux de neurones, deux

  18. Contribution towards the study of {beta}{yields}{alpha} transformation in uranium and its alloys (1962); Contribution a l'etude de la transformation {beta}{yields}{alpha} dans l'uranium et ses alliages (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Aubert, H. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1962-05-15

    The kinetics of the transformation of uranium alloys containing 0.5 - 0.75 - 1.0 - 1.5 and 3 atoms per cent have been studied. The influence of heat treatment before decomposition has been discussed. The study of the transformation characteristics such as kinetics, residual phases, phenomena connected with the coherence between phases, reversibility below the equilibrium temperature, shows the following mechanisms exhibited during the decomposition of the {beta} phase on lowering the temperature: 1 ) eutectoid, 2) bainitic, 3) martensitic. The study of the TTT diagrams of alloys containing decreasing percentages of chromium indicates that the unalloyed uranium transforms without maintaining the coherence above 600 deg. C, where as at lower temperatures the transformation is mainly martensitic. The various alloying elements can be characterised by their influence on the three TTT curves corresponding to the three possible transformation mechanisms. The ability of the uranium alloys to alpha grain refining during isothermal decomposition or ambient temperature quenching is directly connected with the characteristics of the TTT diagrams and especially to the mode of bainitic transformation. (author) [French] II a ete etudie la cinetique de transformation des alliages uranium-chrome de teneur 0,5 - 0,75 - 1 - 1,5 - et 3 atomes pour cent. L'influence des traitements thermiques precedant la decomposition a ete discutee. L'etude des caracteristiques de la transformation: cinetique, phases residuelles, phenomenes lies a la coherence entre phases, reversibilite au-dessous de la temperature d'equilibre, permet de conclure que la decomposition met en jeu successivement les trois mecanismes eutectoide, bainitique et martensitique quand la temperature baisse. L'etude de l'evolution des diagrammes TTT quand la teneur en Cr decroit indique que dans l'uranium non allie la transformation se fait sans maintien de la coherence au-dessus de 600 deg. C; a

  19. Contribution towards the study of {beta}{yields}{alpha} transformation in uranium and its alloys (1962); Contribution a l'etude de la transformation {beta}{yields}{alpha} dans l'uranium et ses alliages (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Aubert, H [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1962-05-15

    The kinetics of the transformation of uranium alloys containing 0.5 - 0.75 - 1.0 - 1.5 and 3 atoms per cent have been studied. The influence of heat treatment before decomposition has been discussed. The study of the transformation characteristics such as kinetics, residual phases, phenomena connected with the coherence between phases, reversibility below the equilibrium temperature, shows the following mechanisms exhibited during the decomposition of the {beta} phase on lowering the temperature: 1 ) eutectoid, 2) bainitic, 3) martensitic. The study of the TTT diagrams of alloys containing decreasing percentages of chromium indicates that the unalloyed uranium transforms without maintaining the coherence above 600 deg. C, where as at lower temperatures the transformation is mainly martensitic. The various alloying elements can be characterised by their influence on the three TTT curves corresponding to the three possible transformation mechanisms. The ability of the uranium alloys to alpha grain refining during isothermal decomposition or ambient temperature quenching is directly connected with the characteristics of the TTT diagrams and especially to the mode of bainitic transformation. (author) [French] II a ete etudie la cinetique de transformation des alliages uranium-chrome de teneur 0,5 - 0,75 - 1 - 1,5 - et 3 atomes pour cent. L'influence des traitements thermiques precedant la decomposition a ete discutee. L'etude des caracteristiques de la transformation: cinetique, phases residuelles, phenomenes lies a la coherence entre phases, reversibilite au-dessous de la temperature d'equilibre, permet de conclure que la decomposition met en jeu successivement les trois mecanismes eutectoide, bainitique et martensitique quand la temperature baisse. L'etude de l'evolution des diagrammes TTT quand la teneur en Cr decroit indique que dans l'uranium non allie la transformation se fait sans maintien de la coherence au-dessus de 600 deg. C; a plus basse temperature la

  20. A continuous acceleration tube of ions under 200 KV; Un tube d'acceleration continue d'ions sous 200 KV

    Energy Technology Data Exchange (ETDEWEB)

    Mongodin, G [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1954-07-01

    The realization of an Van de Graaff accelerator required, for the preliminary studies, the construction of a small proton accelerator, functioning at 200 kV in order to resolve some parasitic effects inherent to the accelerators tubes. The aim of this report is to describe the different organs of the accelerator tube, to explain the operating system and to encode their characteristics. The report first presents the ion source and the beam buncher permitting to inject in the accelerator tube particles of about 9 kV and very batched in a thin beam of circular section. Then the study explain the tube characteristics considered like optic system. A method to obtain precise calculation of particle trajectories is exposed. Aberrations of the system were discussed and balance of the currents on all electrodes inside the tube for different regimes of working were provided. The influence of the residual pressure in the tube were explained. The report finally ends on a part of the fundamental problem of the straining occurring inside the tubes accelerators under high tension. (M.B.) [French] La realisation d n accelerateur du type Van de Graaff a necessite, entre autres etudes preliminaires, la construction d'un petit accelerateur de protons, fonctionnant sous 200 kV afin d'eclaircir certains effets parasites propres aux tubes accelerateurs. L'objet de ce rapport est de decrire les differents organes du tube accelerateur, d'en expliquer le fonctionnement et de chiffrer leurs caracteristiques. Le memoire presente d'abord la source d'ions et le canon permettant d'injecter dans le tube accelerateur des particules de 9 kV environ et bien groupees dans un faisceau fin de section circulaire. Puis il passe a l'etude du tube considere comme systeme optique. Une methode utilisee pour le calcul precis des trajectoires des particules y est exposee. Il aborde le probleme des aberrations de ce systeme et fournit par la suite le bilan des courants sur toutes les electrodes a l

  1. Economic aspects of electricity and industrial heat generating reactors; Aspect economique des reacteurs produisant de l'electricite et de la chaleur industrielle

    Energy Technology Data Exchange (ETDEWEB)

    Gaussens, J; Moulle, N; Dutheil, F [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Aldebert, J [Institut National des Sciences et Techniques Nucleaires (INSTN), CEA Saclay, 91 - Gif sur Yvette (France)

    1964-07-01

    The economic advantage of electricity-generating nuclear stations decreases when their size decreases. However, when a counter-pressure turbine is joined on to a reactor and the residual heat can be properly used, it can be shown that fairly low capacity nuclear equipment may compete with conventional equipment under certain realistic enough conditions. The aim of this paper is to define these special conditions under which nuclear energy can be profitable. They are connected with the location and the general economic environment of the station, the pattern of the electricity and heat demands it must meet, the level of fuel and specific capital costs, nuclear and conventional. These conditions entail certain technical and economic specifications for the reactors used in this way otherwise they are unlikely to be competitive. In addition, these results are referred to the potential steam and electricity market, which leads us to examine certain uses for the heat generated by double purpose power stations; for example, to supply combined industrial plants, various types of town heating and for removal of salt from sea water. (authors) [French] L'interet economique de centrales nucleaires productrices d'electricite decroit lorsque la puissance decroit. Cependant, lorsqu'on associe une turbine a contrepression a un reacteur et qu'il est possible d'utiliser dans de bonnes conditions la chaleur residuelle, on peut montrer que dans certaines conditions assez realistes, des equipements nucleaires d'une puissance unitaire peu elevee peuvent etre competitifs avec des equipements conventionnels. Cette communication a donc pour but de mettre en evidence quelles sont ces conditions particulieres de rentabilite de l'energie nucleaire. Elles sont liees a la localisation de la centrale et a son contexte economique general, a la structure de la demande d'energie electrique et thermique a laquelle elle doit satisfaire, au niveau des couts des combustibles et des investissements

  2. Economic aspects of electricity and industrial heat generating reactors; Aspect economique des reacteurs produisant de l'electricite et de la chaleur industrielle

    Energy Technology Data Exchange (ETDEWEB)

    Gaussens, J.; Moulle, N.; Dutheil, F. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Aldebert, J. [Institut National des Sciences et Techniques Nucleaires (INSTN), CEA Saclay, 91 - Gif sur Yvette (France)

    1964-07-01

    The economic advantage of electricity-generating nuclear stations decreases when their size decreases. However, when a counter-pressure turbine is joined on to a reactor and the residual heat can be properly used, it can be shown that fairly low capacity nuclear equipment may compete with conventional equipment under certain realistic enough conditions. The aim of this paper is to define these special conditions under which nuclear energy can be profitable. They are connected with the location and the general economic environment of the station, the pattern of the electricity and heat demands it must meet, the level of fuel and specific capital costs, nuclear and conventional. These conditions entail certain technical and economic specifications for the reactors used in this way otherwise they are unlikely to be competitive. In addition, these results are referred to the potential steam and electricity market, which leads us to examine certain uses for the heat generated by double purpose power stations; for example, to supply combined industrial plants, various types of town heating and for removal of salt from sea water. (authors) [French] L'interet economique de centrales nucleaires productrices d'electricite decroit lorsque la puissance decroit. Cependant, lorsqu'on associe une turbine a contrepression a un reacteur et qu'il est possible d'utiliser dans de bonnes conditions la chaleur residuelle, on peut montrer que dans certaines conditions assez realistes, des equipements nucleaires d'une puissance unitaire peu elevee peuvent etre competitifs avec des equipements conventionnels. Cette communication a donc pour but de mettre en evidence quelles sont ces conditions particulieres de rentabilite de l'energie nucleaire. Elles sont liees a la localisation de la centrale et a son contexte economique general, a la structure de la demande d'energie electrique et thermique a laquelle elle doit satisfaire, au niveau des couts des

  3. Analysis of stress intensity factors for a new mechanical corrosion specimen; Analyse du facteur d`intensite de contrainte pour une nouvelle eprouvette de mecanique corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Rassineux, B; Crouzet, D; Le Hong, S

    1996-03-01

    Electricite de France is conducting a research program to determine corrosion cracking rates in the steam generators Alloy 600 tubes of the primary system. The objective is to correlate the cracking rates with the specimen stress intensity factor K{sub I}. One of the samples selected for the purpose of this study is the longitudinal notched specimen TEL (TEL: ``Tubulaire a Entailles Longitudinales``). This paper presents the analysis of the stress intensity factor and its experimental validation. The stress intensity factor has been evaluated for different loads using 3D finite element calculations with the Hellen-Parks and G({theta}) methods. Both crack initiation and propagation are considered. As an assessment of the method, the numerical simulations are in good agreement with the fatigue crack growth rates measured experimentally for TEL and compact tension (CT) specimens. (authors). 8 refs., 6 figs., 2 tabs.

  4. Creep of uranium dioxide: bending test and mechanical behaviour; Etude du fluage du dioxyde d'uranium: caracterisation par essais de flexion et modelisation mecanique

    Energy Technology Data Exchange (ETDEWEB)

    Colin, Ch

    2003-09-01

    These PhD work in the frame of Pellet-Cladding Interactions studies, in the fuel assemblies of nuclear plants. Electricite de France (EDF) must well demonstrate and insure the integrity of the cladding. For that purpose, the viscoplastic behaviour of the nuclear fuel has to be known and, if possible, controlled. This PhD work aimed to characterize the creep of uranium dioxide, in conditions of transient power regime. First, a literature survey on mechanical behaviour of UO{sub 2} revealed that the ceramic was essentially studied with compressive tests, and that its creep behaviour is characterized by two domains, depending on the stress level. To estimate the loadings in a fuel pellet, EDF and CEA developed specific global codes. A simulation during a power ramp allowed the order of magnitude of the loadings in the pellet to be determined (temperature, thermal gradients, strains, strain rate...). The stress calculation using a finite element simulation requires the identification of behaviour laws, able to describe the behaviour under small strains, low strain rates, and under tensile stresses. Starting from this observation, three point bending method has been chosen to test the uranium dioxide. As, for representativeness reasons, testing specimens cut in actual fuel pads was required in our study; a ten millimeters span has been used. For this study, a specific three-point testing device has been developed, that can tests specimens up to 2 000 C in a controlled atmosphere (Ar + 5% H{sub 2}). A special care has been taken for the measurement of the deflexion of the sample, which is measured using a laser beam, that allow an accuracy of {+-}2{mu}m to be reached at high temperature. Specimens with 0,5 to 1 mm thickness have been tested using this jig. A Norton's law describe, with respective stress exponent and activation energy values of 1.73 and 540 kJ.mole-1, provided a good description of the stationary creep rate. Then, the mechanical behaviour of the fuel has been modeled. The introduction of internal variables in a law describing a kinematic hardening of the material allowed the first two stages of creep and the recovery phenomena observed during partial un-loadings to be described. The identification was realized by inverse method, coupling an optimization of the parameters with a finite element calculation of the deformation of the bending specimen. The application of this model to simulate a transient power ramp demonstrated that the expected stress relaxation in the fuel does not prevent a radial break of pellet at the end of the power increase. During a maintain at high power, the high temperature in the core of the pellet allows a stress relaxation, especially close from the hollows. That results in a flow of the ceramic, mainly axial, that is clearly confirmed by the observation of used pellets. A final application of our experimental device consisted in testing ion-irradiated specimens, with a 50 {mu}m penetration depth. The small thickness of our samples allows the effect of an irradiation on the creep of UO{sub 2} to be revealed. (author)

  5. Study of the mechanical properties of the electric power station components: the punch test; Etude des proprietes mecaniques des composants de centrales thermiques: l'essai punch test

    Energy Technology Data Exchange (ETDEWEB)

    Isselin, J

    2003-03-15

    The aging of the electric production park implies an increasing need of knowledge concerning the evolution of the mechanical properties of its components. With regard to this problem, the availability in material is more and more small. This work proposes to characterize these properties through a mechanical test called Punch test. The main characteristic of this test is to use very small volume samples. The development of this test has been carried out by the study of a 15 MDV 4-05 steel coming from a steam drum of a thermal power plant after 145000 hours of service. At first, we have measured the influence of the parameters of this test. Then, the study has dealt more particularly on the transition temperature of the material. With the finite element simulation method, the strain hardening coefficient of the material has been determined. (O.M.)

  6. Mechanical characterization and numerical modeling of a rotary X-ray anode; Caracterisation mecanique et simulation numerique d'une anode tournante de rayons X

    Energy Technology Data Exchange (ETDEWEB)

    Lemarchand, G

    2003-04-15

    This works deals with the design of light rotary anodes used for the generation of X-rays in medical scanners. Such anodes are made of graphite coated with tungsten by low pressure plasma sputtering. The mechanical behaviour of these materials during intense thermo-mechanical solicitation has been studied. In a first step, the in-service conditions of solicitation are defined in terms of excitation frequency, temperature, deformation and deformation velocity. The analysis of used anodes has permitted to define the main modes of in-service damage. Tests were performed on small size samples over the complete temperature range between ambient temperature and 1800 deg. C. Carbon has shown a fragile elastic behaviour while tungsten has shown a more complex behaviour: elastic-fragile up to 400 deg. C, then plastic, and becoming creep sensible above 1200 deg. C. Original load paths have permitted to show the existence of an internal back-stress and a coupling between plastic and viscous deformations. The definition of an original phenomenological law of behaviour with a double inelastic, plastic and visco-plastic deformation and with an interaction term between both flow mechanisms has been necessary to describe the mechanical behaviour of tungsten. The cold-drawing generated by each flow is translated into kinematic variables. The numerical identification of the parameters has been performed using an optimizer coupled to a finite element code which simulates the flexural test. The obtained law has been validated by the experimental observation of paths for complex loads. This behaviour law has been finally used to simulate the conditions of use of a real anode. An axisymmetrical 2-D mesh has permitted to calculate the constraints generated by the post-annealing cooling, by one and several series of radiographies and finally by a complete cooling after use. The repetition of radiographies rapidly leads to stabilized cycles. The calculated stress levels are realistic and remain inferior to the rupture resistance of the materials. This simulation can already be industrially used to evaluate the influence of a change in the anode geometry or in the conditions of in-service constraints. (J.S.)

  7. Rupture mechanics of metallic alloys for hydrogen transport; Mecanique de la rupture des alliages metalliques pour le transport de l'hydrogene

    Energy Technology Data Exchange (ETDEWEB)

    Moro, I.; Briottet, L.; Lemoine, P. [CEA Grenoble (DRT/LITEN/DTH/LEV), 38 (France); Andrieu, E.; Blanc, C. [Centre Interuniversitaire de Recherche et d' Ingenierie des Materiaux (ENSIACET/CIRIMAT), 31 - Toulouse (France)

    2007-07-01

    With the aim to establish a cheap hydrogen distribution system, the transport by pipelines is a solution particularly interesting. Among the high limit of elasticity steels, the X80 has been chosen for hydrogen transport. Its chemical composition and microstructure are given. Important microstructural changes have been revealed in the sheet thickness: the microstructure is thinner and richer in perlite in surface than in bulk. In parallel to this microstructural evolution, a microhardness gradient has been observed: the material microhardness is stronger in surface than in bulk of the sheet. The use of this material for hydrogen transport requires to study its resistance to hydrogen embrittlement. The main aim of this work is to develop an easy rupture mechanics test allowing to qualify the studied material in a gaseous hydrogen environment, to determine the sensitivity of the studied material to the hydrogen embrittlement and to better understand the mechanisms of the hydrogen embrittlement for ferritic materials. Two experimental tests have been used for: the first one is a traction machine coupled to an autoclave; the second one allows to carry out disk rupture tests. The toughness of the material in a gaseous hydrogen environment has thus been determined. The resistance of the material to hydrogen embrittlement has been characterized and by simulation, it has been possible to identify the areas with a strong concentration in hydrogen. The second aim of this work is to study the influence of the steel microstructure on the hydrogen position in the material and on the resistance of the material to the hydrogen embrittlement. The preferential trapping sites on the material not mechanically loaded have at first been identified, as well as the hydrogen position on the different phases and at the ferrite/cementite interface. The interaction between the mechanical loads, the position and the trapping of the hydrogen have been studied then. At last, has been established a link between the preferential localization of hydrogen and the results of the rupture mechanics tests in a gaseous hydrogen environment. (O.M.)

  8. A geometric criterion for the stability of forced oscillations in non-linear mechanics (1961); Un critere geometrique de stabilite des oscillations forcees en mecanique non lineaire (1961)

    Energy Technology Data Exchange (ETDEWEB)

    Blaquiere, A [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-07-01

    The author completes the two-parameter diagram theory which he has previously explained, by giving a geometric criterion of stability for a non-linear system under forced conditions. After two simple geometric transformations of the diagram he obtains the separators which are the boundary conditions for the zones of stability. (author) [French] L'auteur complete la theorie du diagramme a deux parametres, qu'il a anterieurement exposee, par l'enonce d'un critere geometrique de stabilite, relatif aux regimes forces d'un systeme non lineaire. Il obtient, par deux transformations geometriques simples du diagramme, les separatrices qui delimitent les zones de stabilite. (auteur)

  9. Curing paints in mechanical industry, state of the art, optimization; Cuisson de peinture dans l`industrie mecanique, etat de l`art, optimisation

    Energy Technology Data Exchange (ETDEWEB)

    Brandon, B. [ERIC, (France)]|[CETIAT, Centre Technique des Industries Aerauliques et Thermiques, 69 - Villeurbanne (France)

    1996-12-31

    The thermal polymerization of paints, or curing, in the mechanical industry sector, is facing increasing constraints due to new coating characteristics, environmental issues and economical competitiveness. The various curing technologies (hot air, infrared radiations) are reviewed and an extensive analysis of 20 curing plants is presented: assessment of the energy performances of the plant, determination of the curing cycles, and evaluation of the coating quality. An optimized solution has been derived for a typical plant, showing a reduction in cycle times due to a mixed convection-infrared oven, and its energy efficiency is discussed

  10. Influence aqueous solutions on the mechanical behavior of argillaceous rocks; Influence des solutions aqueuses sur le comportement mecanique des roches argileuses

    Energy Technology Data Exchange (ETDEWEB)

    Wakim, J

    2005-12-15

    The hydration of the shale with an aqueous solution induces a swelling deformation which plays an important role in the behaviour of the structures excavated in this type of grounds. This deformation is marked by a three-dimensional and anisotropic character and involves several mechanisms like adsorption, osmosis or capillarity. Several researches were dedicated to swelling and were often much debated due to the complexity of the implied phenomena. The goal of this thesis is therefore to contribute to a better understanding of shale swelling when the rock is confined and hydrated with an aqueous solution. The main part of the work accomplished was related to the Lorraine shale and to the Tournemire shale. To characterize swelling and to identify the main governing parameters, it was necessary to start the issue with an experimental approach. Many apparatus were then developed to carry out tests under various conditions of swelling. In order to facilitate the interpretation of the tests and thereafter the modelling of the behaviour, the experimental procedure adopted consisted of studying first the mechanical aspect and then the chemical aspect of swelling. In the mechanical part, swelling was studied by imposing on the sample a mechanical loading while maintaining during the tests the same aqueous solution. The principal parameters which were studied are the effect of the lateral conditions on axial swelling (impeded strain or constant stress) as well as the influence of the axial stress on radial swelling. The anisotropy of swelling was studied by carrying out, for different orientations of the sample, tests of free swelling, impeded swelling and uniaxial swelling. These various mechanical tests allowed to study the three-dimensional anisotropic swelling in all the conditions and to select the most appropriate test to be used in the second phase of the research. The precise analysis performed to explain the mechanisms behind the swelling of an argillaceous rock when it is in contact of water showed that the mechanical response is ruled mainly by electrochemical phenomena which operate between the solution elements and the clay layers. This important result oriented the research to develop better the role of the chemistry in the behaviour. Swelling was therefore analysed by imposing on the sample a chemical loading while maintaining constant the axial stress. Monovalent and divalent salts which were used with various concentrations are the sodium chloride (NaCl), the potassium chloride (KCl) and the calcium chloride (CaCl{sub 2}). The foreseen objective was to analyze the effect of the chemical path with decreasing or cyclic concentrations and to highlight the role of the solution normality, the type of salt and the anisotropy on the axial swelling. The experimental results obtained allowed the development of a new rheological model which takes into account the time, the anisotropy, the applied loading and the chemistry of the solution. This model was implemented in a finite element code to simulate simple cases and to prove its validity. (author)

  11. Understanding the mechanics of processes of recolonization of vegetation in mined peat bogs; Comprendre la mecanique du processus de recolonisation vegetale des tourbieres exploitees

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, D. [Laval University, Quebec, QC (Canada). Department of Biology

    2002-07-01

    The recolonization process in abandoned milled peat bogs was studied to determine why the recolonization of such sites is difficult. The process was considered as a series of environmental filters where only those species with suitable ecological characteristics survive. Several species of mosses, ericaceous shrubs, and trees were studied. The stability of milled peat surfaces was examined with regard to wind erosion potential as a function of decomposition, surface roughness of milled peats, and milled peat substrate stability in a second field study. The germination of and establishment potential of vascular plants was examined in a third study.

  12. Supply of clean water to the bearings and mechanical seals of the backup pumps; Alimentation en eau propre des paliers et garnitures mecaniques des pompes de sauvetage

    Energy Technology Data Exchange (ETDEWEB)

    Jolas, C. [Department Machines, Service Ensembles de Production, Direction des Etudes et Recherches, Electricite de France (EDF), 92 - Clamart (France)

    1997-01-01

    The purpose of the backup pumps is to cool the primary circuit and pressurised water reactor containment in the case of a primary cooler loss accident. The water taken in by these pumps in the case of accident is loaded with solid particles. In order to ensure correct operation of the bearings and mechanical seals of these machines, they must be supplied with clean water. In other words, the solid particles must be removed from the water intake. Manufacturers generally use cyclonic separators to achieve this. (author) 5 refs., 14 figs.

  13. Proceedings [of the] CSME [Canadian Society for Mechanical Engineering] forum 1992: Transport 1992+. Comptes rendus [de la] forum SCGM [Societe canadienne de genie mecanique] 1992: Transport 1992+

    Energy Technology Data Exchange (ETDEWEB)

    Sankar, S.; Rakheja, S.; Richard, M.; Mahoney, T. (eds.)

    1992-01-01

    A conference was held to discuss engineering aspects of transportation. Papers were presented on the dynamics of off-road vehicles and mobility, vehicle system dynamics, human factors in transportation, alternate fuels and the environment, mobile robots and vehicles, advanced manufacturing systems, rail transportation systems, design automation for transportation industries, freight and passenger transport systems, and road transportation challenges and systems. Separate abstracts have been prepared for 14 papers from the conference.

  14. Topological field theories and quantum mechanics on commutative space; Theories des champs topologiques et mecanique quantique en espace non-commutatif

    Energy Technology Data Exchange (ETDEWEB)

    Lefrancois, M

    2005-12-15

    In particle physics, the Standard Model describes the interactions between fundamental particles. However, it was not able till now to unify quantum field theory and general relativity. This thesis focuses on two different unification approaches, though they might show some compatibility: topological field theories and quantum mechanics on non-commutative space. Topological field theories have been introduced some twenty years ago and have a very strong link to mathematics: their observables are topological invariants of the manifold they are defined on. In this thesis, we first give interest to topological Yang-Mills. We develop a superspace formalism and give a systematic method for the determination of the observables. This approach allows, once projected on a particular super gauge (of Wess-Zumino type), to recover the existing results but it also gives a generalisation to the case of an unspecified super-gauge. We have then be able to show that the up-to-now known observables correspond to the most general form of the solutions. This superspace formalism can be applied to more complex models; the case of topological gravity is given here in example. Quantum mechanics on noncommutative space provides an extension of the Heisenberg algebra of ordinary quantum mechanics. What differs here is that the components of the position or momentum operators do not commute with each other anymore. This implies to introduce a fundamental length. The second part of this thesis focuses on the description of the commutation algebra. Applications are made to low-dimensional quantum systems (Landau system, harmonic oscillator...) and to supersymmetric systems. (author)

  15. Coupling between mechanical behaviour and drying of cementing materials: experimental study on mortars; Couplage comportement mecanique et dessiccation des materiaux a matrice cimentaire: etude experimentale sur mortiers

    Energy Technology Data Exchange (ETDEWEB)

    Yurtdas, I

    2003-10-15

    The aim of this work is to understand the desiccation effects on the mechanical behaviour of cement materials. Two mortars of ratio E/C=0.5 and 0.8 have been tested. All the tests have been implemented after a six months maturing in water. The experimental study has been carried out as follows: 1)tests characterizing the differed behaviour and the transport properties have been carried out 2)tests characterizing the short term multiaxial mechanical behaviour have been carried out. The desiccation shrinkage in terms of the weight loss presents three characteristic phases. The permeability measurement on the mortar 05 shows that the permeability of the specimens dried and crept is greater than those of the specimens dried before being crept, and the permeability of the specimens submitted to a desiccation creep and then dried is sensibly the same as the last one in spite of a very important differed deformation. The influence of the desiccation on the uniaxial and deviatoric compressions resistance depends of the binding agent: for a cement paste of good quality (E/C=0.5), the resistances increase with the desiccation because of the capillary depression and of the hydric gradients. For a cement paste of low quality (E/C=0.8), there is a competitive effect between the increase of the microcracks induced and the specimen rigidification; the microcracking becomes then the parameter controlling the rupture process. The elasto-plastic behaviour becomes a damageable elasto-plastic behaviour during desiccation which induces, as the decrease of the E/C ratio, a translation of the elastic limit surfaces and ruptures towards higher stresses. In parallel, the elastic properties and the incompressibility modulus are damaged and the volume deformations increase after the drying. At last, the decrease of the Young modulus and the passage to the third shrinkage phase in terms of the weight loss coincide. This can be attributed to the induced microcracking: this decrease of the Young modulus could be explained too by a part of the desiccation creep. (O.M.)

  16. Metallurgical and mechanical behaviours of PWR fuel cladding tube oxidised at high temperature; Comportements metallurqigue et mecanique des materiaux de gainage du combustible REP oxydes a haute temperature

    Energy Technology Data Exchange (ETDEWEB)

    Stern, A

    2007-12-15

    Zirconium alloys are used as cladding materials in Pressurized Water Reactors (PWR). As they are submitted to very extreme conditions, it is necessary to check their behaviour and especially to make sure they meet the safety criteria. They are therefore studied under typical in service-loadings but also under accidental loadings. In one of these accidental scenarios, called Loss of Coolant Accident (LOCA) the cladding temperature may increase above 800 C, in a steam environment, and decrease before a final quench of the cladding. During this temperature transient, the cladding is heavily oxidised, and the metallurgical changes lead to a decrease of the post quench mechanical properties. It is then necessary to correlate this drop in residual ductility to the metallurgical evolutions. This is the problem we want to address in this study: the oxidation of PWR cladding materials at high temperature in a steam environment and its consequences on post quench mechanical properties. As oxygen goes massively into the metallic part - a zirconia layer grows at the same time - during the high temperature oxidation, the claddings tubes microstructure shows three different phases that are the outer oxide layer (zirconia) and the inner metallic phases ({alpha}(O) and 'ex {beta}') - with various mechanical properties. In order to reproduce the behaviour of this multilayered material, the first part of this study consisted in creating samples with different - but homogeneous in thickness - oxygen contents, similar to those observed in the different phases of the real cladding. The study was especially focused on the {beta}-->{alpha} phase transformation upon cooling and on the resulting microstructures. A mechanism was proposed to describe this phase transformation. For instance, we conclude that for our oxygen enriched samples, the phase transformation kinetics upon cooling are ruled by the oxygen partitioning between the two allotropic phases. Then, these materials were mechanically tested at various temperatures and for various mean oxygen contents. This allowed us, first, to establish ductile to brittle transition temperatures (for a given oxygen content), and second, to establish behaviour laws for those materials (function of oxygen content and temperature). It was thus possible to start some preliminary finite element calculations to describe the cladding behaviour under the standard technological ring compression test. (author)

  17. Micromechanical simulation of Uranium dioxide polycrystalline aggregate behaviour under irradiation; Modele numerique micro-mecanique d'agregat polycristallin pour le comportement des combustibles oxydes

    Energy Technology Data Exchange (ETDEWEB)

    Pacull, J.

    2011-02-15

    In pressurized water nuclear power reactor (PWR), the fuel rod is made of dioxide of uranium (UO{sub 2}) pellet stacked in a metallic cladding. A multi scale and multi-physic approaches are needed for the simulation of fuel behavior under irradiation. The main phenomena to take into account are thermomechanical behavior of the fuel rod and chemical-physic behavior of the fission products. These last years one of the scientific issue to improve the simulation is to take into account the multi-physic coupling problem at the microscopic scale. The objective of this ph-D study is to contribute to this multi-scale approach. The present work concerns the micro-mechanical behavior of a polycrystalline aggregate of UO{sub 2}. Mean field and full field approaches are considered. For the former and the later a self consistent homogenization technique and a periodic Finite Element model base on the 3D Voronoi pattern are respectively used. Fuel visco-plasticity is introduced in the model at the scale of a single grain by taking into account specific dislocation slip systems of UO{sub 2}. A cohesive zone model has also been developed and implemented to simulate grain boundary sliding and intergranular crack opening. The effective homogenous behaviour of a Representative Volume Element (RVE) is fitted with experimental data coming from mechanical tests on a single pellet. Local behavior is also analyzed in order to evaluate the model capacity to assess micro-mechanical state. In particular, intra and inter granular stress gradient are discussed. A first validation of the local behavior assessment is proposed through the simulation of intergranular crack opening measured in a compressive creep test of a single fuel pellet. Concerning the impact of the microstructure on the fuel behavior under irradiation, a RVE simulation with a representative transient loading of a fuel rod during a power ramp test is achieved. The impact of local stress and strain heterogeneities on the multi-physic simulation is discussed. (author)

  18. Modeling of the mechanical behaviour of welded structures: behaviour laws and rupture criteria; Modelisation du comportement mecanique de structures soudees: lois de comportement et criteres de rupture

    Energy Technology Data Exchange (ETDEWEB)

    Paris, T.; Delaplanche, D. [CEA Valduc, Laboratoire Calcul et Simulations, 21120 Is-sur-Tille (France); Saanouni, K. [LASMIS-CNRS-FRE 2719, Universite de Technologie de Troyes BP 2060 - 10010 Troyes - (France)

    2006-07-01

    In the framework of the technological developments carried out in the CEA, the analysis of the mechanical behaviour of the heterogeneous welded bonds Ta/TA6V is a main preoccupation. Indeed, the welding of these two materials which cannot be distinguished by their mechanical and thermal properties induces strong microstructural heterogeneities in the melted zone. In order to characterize the behaviour of the welded joints and to develop a model of mechanical behaviour, a four points bending test on a notched specimen has been developed and implemented. This new test has allowed to obtain a macroscopic response of strength-displacement type but to analyze too more finely, with an optical extensometry and images correlation method, the influence of the heterogeneities on the local deformation of the welded joint. The confrontation of these results to a metallurgical study allows to validate the first conclusions deduced of the mechanical characterization tests and to conclude as for the local mechanisms governing the behaviour and the damage of the melted zone. The mechanical behaviour can be restored by an elasto-viscoplastic model with isotropic and non linear kinematic strain hardening coupled to this damage. The proposed model allows to identify the macroscopic behaviour of the weld bead. (O.M.)

  19. Mechanical characterization and numerical modeling of a rotary X-ray anode; Caracterisation mecanique et simulation numerique d'une anode tournante de rayons X

    Energy Technology Data Exchange (ETDEWEB)

    Lemarchand, G

    2003-04-15

    This works deals with the design of light rotary anodes used for the generation of X-rays in medical scanners. Such anodes are made of graphite coated with tungsten by low pressure plasma sputtering. The mechanical behaviour of these materials during intense thermo-mechanical solicitation has been studied. In a first step, the in-service conditions of solicitation are defined in terms of excitation frequency, temperature, deformation and deformation velocity. The analysis of used anodes has permitted to define the main modes of in-service damage. Tests were performed on small size samples over the complete temperature range between ambient temperature and 1800 deg. C. Carbon has shown a fragile elastic behaviour while tungsten has shown a more complex behaviour: elastic-fragile up to 400 deg. C, then plastic, and becoming creep sensible above 1200 deg. C. Original load paths have permitted to show the existence of an internal back-stress and a coupling between plastic and viscous deformations. The definition of an original phenomenological law of behaviour with a double inelastic, plastic and visco-plastic deformation and with an interaction term between both flow mechanisms has been necessary to describe the mechanical behaviour of tungsten. The cold-drawing generated by each flow is translated into kinematic variables. The numerical identification of the parameters has been performed using an optimizer coupled to a finite element code which simulates the flexural test. The obtained law has been validated by the experimental observation of paths for complex loads. This behaviour law has been finally used to simulate the conditions of use of a real anode. An axisymmetrical 2-D mesh has permitted to calculate the constraints generated by the post-annealing cooling, by one and several series of radiographies and finally by a complete cooling after use. The repetition of radiographies rapidly leads to stabilized cycles. The calculated stress levels are realistic and remain inferior to the rupture resistance of the materials. This simulation can already be industrially used to evaluate the influence of a change in the anode geometry or in the conditions of in-service constraints. (J.S.)

  20. Modeling of the dynamical combustion of explosives: influence of mechanical properties; Modelisation de la combustion dynamique des explodifs: influence des proprietes mecaniques

    Energy Technology Data Exchange (ETDEWEB)

    Picart, D.; Pertuis, C. [CEA Le Ripault, 37 - Tours (France)

    1996-12-31

    Experimental observations performed during the combustion of solid explosives under pressure have shown an unexpected desensitization of the samples when damaged. A simplified method of combustion simulation inside a pressure cell is proposed in this study. The model used is based on the description of the mechanical behaviour of the solid phase. It allows to retrieve the overall experimental results, and in particular the occurrence of anomalous combustion modes. (J.S.) 8 refs.

  1. Electronic specific heat of transition metal carbides; Chaleur specifique electronique de carbures de metaux de transition

    Energy Technology Data Exchange (ETDEWEB)

    Conte, R [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1964-07-15

    The experimental results that make it possible to define the band structure of transition metal carbides having an NaCI structure are still very few. We have measured the electronic specific heat of some of these carbides of varying electronic concentration (TiC, either stoichiometric or non-stoichiometric, TaC and mixed (Ti, Ta) - C). We give the main characteristics (metallography, resistivity, X-rays) of our samples and we describe the low temperature specific heat apparatus which has been built. In one of these we use helium as the exchange gas. The other is set up with a mechanical contact. The two use a germanium probe for thermometer. The measurement of the temperature using this probe is described, as well as the various measurement devices. The results are presented in the form of a rigid band model and show that the density of the states at the Fermi level has a minimum in the neighbourhood of the group IV carbides. (author) [French] Les donnees experimentales permettant de preciser la structure de bandes des carbures de metaux de transition de structure NaCI sont encore peu.nombreuses. Nous avons mesure la chaleur specifique electronique de certains de ces carbures, de differentes concentrations electroniques (TiC stoechiometrique ou non, TaC et mixtes (Ti, Ta) - C). Nous donnons les principales caracteristiques (metallographie, resistivite, rayon X), de nos echantillons, et nous decrivons l'appareillage de chaleur specifique a basse temperature realise. Dans l'un nous utilisons l'helium comme gaz d'echange. L'autre est monte avec un contact mecanique. Les deux utilisent une sonde au germanium comme thermometre. La mesure de la resistance de cette sonde est decrite, ainsi que les differents montages de mesure. Les resultats, presentes dans un modele de bande rigide, font apparaitre que la densite des etats au niveau de Fermi presente un minimum au voisinage des carbures du groupe IV. (auteur)

  2. Transistorized pulse amplifiers (A.I.T.); Amplificateurs d'impulsions a transistors (A.I.T.)

    Energy Technology Data Exchange (ETDEWEB)

    Feyt, J; Couly, J P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1962-07-01

    The two amplifiers whose design and operation are described in this report have been studied for neutron detection units used in piles. They are designed to allow an important reduction of the volume and of the weight of the detector and its amplifier, and to simplify the operation of the detection assembly. To these characteristics can be added the mechanical and electrical robustness and the very reduced micro-phony. The first transistorized amplifier (AIT.1) is simple, very robust, and can be used for radioprotection installations. The second (AIT.4) has a better performance and makes it possible to replace the APT.2 in most of its applications (it has even been used satisfactorily in an apparatus where the micro-phony and the sensitivity to interference of the APT.2 made this latter unusable). (author) [French] Les deux amplificateurs dont ce rapport decrit la conception et le fonctionnement ont ete etudies pour les ensembles de detection des neutrons aupres des piles. Ils ont ete concus pour permettre une reduction importante du volume et du poids du detecteur et de son amplificateur, et pour simplifier le fonctionnement de l'ensemble de detection. A ces caracteristiques s'ajoutent une grande robustesse mecanique et electrique et une microphonie quasi nulle. Le premier amplificateur a transistors (AIT.1) simple, tres robuste, convient pour les installations de radioprotection. Le deuxieme (AIT.4) de performances plus elevees permet de remplacer l'APT.2 dans la plupart de ses applications (il a meme ete utilise avec satisfaction dans un montage ou la microphonie et la sensibilite aux parasites de l'APT.2 rendaient celui-ci inutilisable). (auteur)

  3. Magnesium and related low alloys

    Energy Technology Data Exchange (ETDEWEB)

    Bernard, J; Caillat, R; Darras, R [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1959-07-01

    In the first part the authors examine the comparative corrosion of commercial magnesium, of a magnesium-zirconium alloy (0,4 per cent {<=} Zr {<=} 0,7 per cent) of a ternary magnesium-zinc-zirconium alloy (0,8 per cent {<=} Zn {<=} 1,2 per cent) and of english 'Magnox type' alloys, in dry carbon dioxide-free air, in damp carbon dioxide-free air, and in dry and damp carbon dioxide, at temperatures from 300 to 600 deg. C. In the second part the structural stability of these materials is studied after annealings, of 10 to 1000 hours at 300 to 450 deg. C. Variations in grain after these heat treatments and mechanical stretching properties at room temperature are presented. Finally various creep rate and life time diagrams are given for these materials, for temperatures ranging from 300 to 450 deg. C. (author) [French] Dans une premiere partie les auteurs etudient la corrosion comparee du magnesium commercial, d'un alliage magnesium-zirconium (0,4 pour cent {<=} Zr {<=} 0,7 pour cent), d'un alliage ternaire magnesium-zinc-zirconium (0,8 pour cent {<=} Zn {<=} 1,2 pour cent), et d'alliages anglais 'type Magnox', dans l'air sec decarbonate, l'air humide decarbonate, le gaz carbonique sec et humide a des temperatures de 300 a 600 deg. C. Dans une seconde partie, est etudiee la stabilite structurale de ces materiaux apres des recuits de 300 a 450 deg. C, et de 10 a 1000 heures. Sont presentees les variations, apres ces traitements thermiques, de la grosseur du grain, et des caracteristiques mecaniques de traction a la temperature ambiante. Enfin, quelques diagrammes de vitesse de fluage et de durees de vie sont presentes sur ces materiaux pour des temperatures variant entre 300 et 450 deg. C. (auteur)

  4. Preliminary studies of vanadium-base alloys intended for use in fabrication of cans for fast reactors; Etudes preliminaires sur les alliages a base de vanadium envisages pour la fabrication de gaines de reacteurs rapides

    Energy Technology Data Exchange (ETDEWEB)

    Conte, M [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1967-03-15

    1050 deg. C sous vide montrent que d'une facon generale, les elements d'additions ameliorent les proprietes mecaniques du vanadium. Apres des traitements de corrosion dans une boucle a sodium liquide purifie par piege froid, les alliages sont fragilises a la temperature ambiante. Seule la nuance V-20 pour cent Ti conserve des proprietes plastiques. Ces alliages sont recouverts d'une couche superficielle de carbure de vanadium VC. Apres des traitements dans une boucle a sodium liquide purifie par piege chaud, tous les alliages conservent de bonnes caracteristiques mecaniques. La couche superficielle qui les recouvre est constituee de deux carbures de vanadium VC et {sub {gamma}}VC et d'un sous-oxyde de vanadium VO{sub 0,9}. (auteur)

  5. Physico-chemical study of coating plasma duplex alumina/hydroxyapatite for medical applications relation elaboration/structure/properties(dissolution/adherence/residual constraints); Etude physico-chimique de depots plasma duplex alumine/hydroxyapatite pour applications medicales relations elaboration/structure/proprietes (dissolution/adherence/contraintes residuelles)

    Energy Technology Data Exchange (ETDEWEB)

    Demonet, N

    1998-11-19

    The physico-chemical behavior of porous ceramics depositing is studied in order to use them to favour the biological fixing of hip prosthesis fixed without cement. Alumina depositing, hydroxyapatite depositing and duplex (the both together) have been realized by plasma projection on a substrate in Ti-6Al-V. Tests of dissolution have been made. An original method of sound followed by radioactive tracers has allowed to establish an order of phases degradation and to consider the kinetics of calcium ions in function of several parameters of tests. (N.C.)

  6. Gamma activity and residual power of a shutdown reactor after an irregular operating. Acta code for IBM computer 7094, 360 or CDC 6600; Activite gamma et puissance residuelle d'un reacteur a l'arret apres un fonctionnement irregulier. Programme Acta pour calculateur IBM 7094, 360 ou CDC 6600

    Energy Technology Data Exchange (ETDEWEB)

    Rafalovitch, A

    1967-07-01

    the aim of this study is to evaluate the influence of the power variation in time. The calculation method and the associated software are described. The last chapter applied the method to a determined problem. (A.L.B.)

  7. Contribution of the PET-CT with {sup 18}F.D.G. in the non metastatic thyroid cancers with suspicion of residual or recurrent disease; Apport de la TEP-TDM au {sup 18}FDG dans les cancers de la thyroide non metastatiques avec suspicion de maladie residuelle ou recidivante

    Energy Technology Data Exchange (ETDEWEB)

    Ghander, C.; Taieb, D.; Tessonnier, L.; Mundler, O. [CHU Timone, Service central de biophysique et de medecine nucleaire, 13 - Marseille (France); Sebag, F.; Henry, J.F. [CHU Timone, service central de chirurgie generale et endocrinienne, 13 - Marseille (France); De Micco, C. [Inserm U555, service d' anatomopathologie, 13 - Marseille (France)

    2010-07-01

    Purpose: Recurrent thyroid carcinomas usually involve the cervical lymph nodes. The objective of this study was to evaluate the contribution of {sup 18}F-F.D.G. PET in the investigation of thyroid cancer compared with non-metastatic cervical echography. Conclusions: Due to the low overall sensitivity of PET / CT in thyroid carcinoma, its use should be reserved for cases of aggressive carcinoma and when the residual thyroglobulin under stimulation is high. In these cases it is a complementary information with neck echography. (N.C.)

  8. R7T7 glass alteration mechanism in an aqueous closed system: understanding and modelling the long term alteration kinetic; Etude des mecanismes d'alteration par l'eau du verre R7T7 en milieu confine: comprehension et modelisation de la cinetique residuelle

    Energy Technology Data Exchange (ETDEWEB)

    Chave, T

    2007-10-15

    The long term alteration rate of the French R7T7 nuclear glass has been investigated since many years because it will define the overall resistance of the radionuclide containment matrix. Recent studies have shown that the final rate remains constant or is slightly decreasing with time. It never reaches zero. Though this residual rate is very low, only 5 nm per year at 50 C, it would be the dominant alteration phenomenon in a geological repository. Two mechanisms are suggested for explaining such behaviour: diffusion in solution of elements from glass through an amorphous altered layer and precipitation of neo-formed phases. The diffusion processes are in agreement with a solid state diffusion mechanism and can lead to secondary phase precipitation due to solution concentration increases. Observed phases are mainly phyllosilicates and zeolites, in specific conditions. Phyllosilicates are expected to maintain the residual kinetic rate whereas alteration resumption could be observed in presence of zeolites at very high pH or temperature (10.5 at 90 C or temperature above 150 C). Both diffusion and neo-formed phase precipitation have been investigated in order to better understand their impact on the residual alteration rate and have then been modelled by a calculation code, coupling chemistry and transport, in order to be able to better anticipate the long term behaviour of the glass R7T7 in an aqueous closed system. (author)

  9. Dispersion-Type Absorbing Materials for the Control Organs of Thermal Reactors; Absorbants du Type a Dispersion pour les Organes de Commande des Reacteurs a Neutrons Thermiques; Pogloshchayushchie materialy dispersionnogo tipa dlya organov regulirovaniya teplovykh reaktorov; Absorbentes de Tipo Dispersion para los Organos de Mando de los Reactores Termicos

    Energy Technology Data Exchange (ETDEWEB)

    Nosov, V. I.; Ponomarjov-Stepnoj, H. H.; Portnoj, K. I.; Savel' ev, E. G.

    1964-06-15

    The paper gives the results of a study of the physical characteristics of NIMONIC-type absorbing alloys with oxides of rare-earth elements dispersed in them (gadolinium, samarium, europium etc. ). The paper discusses changes in absorbing capacity in relation to the composition of the material, describes the mechanical and thermophysical properties of the absorbing materials as a function of the concentration of absorber introduced into the alloy and, finally, gives the results of a study of the effect of radiation on the properties of the materials. It is shown that absorbing alloys with oxides of rare-earth elements dispersed in the metallic matrix possess considerable absorbing capacity for relatively small amounts of absorber in the alloy (5 to 10%). When oxides of rare-earth elements are added, NIMONIC-type alloys have relatively high resistance and thermophysical characteristics (o{sub B}, E, {lambda}) at high temperatures for absorber concentrations up to about 10%. Dispersion materials of this type have satisfactory radiation stability in a radiation field of about 3 x 10{sup 20}n/cm{sup 2} at high temperature. (author) [French] Les auteurs exposent les resultats de recherches sur les caracteristiques physiques des alliages absorbants du type nimonik, contenant des terres rares dispersees dans leur masse (gadolinium, samarium, europium, etc.). Ils examinent les variations de la capacite d'absorption selon la composition du materiau; on donne des indications sur les caracteristiques mecaniques et thermophysiques des absorbants en fonction de la concentration de Tabsorbeur incorpore dans l 'alliage ainsi que les resultats d 'une etude relative a l 'influence de l'irradiation sur ces caracteristiques. Ils montrent que les alliages absorbants contenant des oxydes de terres rares disperses dans une matrice metallique ont une capacite d'absorption importante pour une teneur de l'alliage relativement faible en'matieres absorbantes (environ 5 a 10%). Les alliages du

  10. Specific features of NDT data and processing algorithms: new remedies to old ills; Caracteristiques specifiques des donnees de controle non destructif et algorithmes de traitement: nouveaux remedes aux vielles douleurs

    Energy Technology Data Exchange (ETDEWEB)

    Georgel, B

    1994-12-31

    Non destructive testing data from in-service inspections have specific features that require the most sophisticated techniques of signal and image processing. Each step in the overall information extraction process must be optimized by using recent approaches such like data decomposition and modelization, compression, sensor fusion and knowledge based systems. This can be achieved by means of wavelet transform, inverse problems formulation, standard compression algorithms, combined detection and estimation, neural networks and expert systems. These techniques are briefly presented through a number of Electricite de France applications or through recent literature results. (author). 1 fig., 20 refs.

  11. The construction of the graphite calorimeter GR9 at LNE-LNHB (geometrical and technical consideration); Construction du calorimetre en graphite GR9 au LNE-LNHB (caracteristiques techniques et geometriques)

    Energy Technology Data Exchange (ETDEWEB)

    Ostrowsky, A.; Daures, J

    2008-07-01

    Calorimetry is the most direct dosimetric technique to reach absorbed dose. A calorimeter gives direct access to the energy imparted to matter by ionizing radiation per mass unit by measuring the heat quantity Q produced under irradiation in its sensitive element which is thermally insulated. Graphite was chosen as construction material because all the energy imparted to graphite by ionizing radiation is converted into heat. Thermistors are used for temperature measurements as well as for the electrical heating of the different bodies of the calorimeter. The construction of a calorimeter is the result of a compromise between dosimetric requirements and mechanical constraints. The difficulties encountered are examined and the solutions chosen are detailed. All technical data are gathered in this document. The aim is to provide a practical operative instruction and guidance document, which can help interested laboratories in designing such an instrument. The electrical and thermal tests have shown a good behaviour of the GR9 calorimeter.

  12. Design of the control room of the N4-type PWR: main features and feedback operating experience; La salle de commande du palier N4: principales caracteristiques et retour d'experience d'exploitation

    Energy Technology Data Exchange (ETDEWEB)

    Peyrouton, J.M.; Guillas, J.; Nougaret, Ch. [Electricite de France (EDF/DPN/CAPE), 93 - Saint-Denis (France)

    2004-07-01

    This article presents the design, specificities and innovating features of the control room of the N4-type PWR. A brief description of control rooms of previous 900 MW and 1300 MW -type PWR allows us to assess the change. The design of the first control room dates back to 1972, at that time 2 considerations were taken into account: first the design has to be similar to that of control rooms for thermal plants because plant operators were satisfied with it and secondly the normal operating situation has to be privileged to the prejudice of accidental situations just as it was in a thermal plant. The turning point was the TMI accident that showed the weight of human factor in accidental situations in terms of pilot team, training, procedures and the ergonomics of the work station. The impact of TMI can be seen in the design of 1300 MW-type PWR. In the beginning of the eighties EDF decided to launch a study for a complete overhaul of the control room concept, the aim was to continue reducing the human factor risk and to provide a better quality of piloting the plant in any situation. The result is the control room of the N4-type PWR. Today the cumulated feedback experience of N4 control rooms represents more than 20 years over a wide range of situations from normal to incidental, a survey shows that the N4 design has fulfilled its aims. (A.C.)

  13. Non-destructive analysis and detection of internal characteristics of spruce logs through X computerized tomography; Detection et analyse non destructive de caracteristiques internes de billons d'epicea commun (PICEA ABIES (L.) KARST) par tomographie a rayons X

    Energy Technology Data Exchange (ETDEWEB)

    Longuetaud, F

    2005-10-15

    Computerized tomography allows a direct access to internal features of scanned logs on the basis of density and moisture content variations. The objective of this work is to assess the feasibility of an automatic detection of internal characteristics with the final aim of conducting scientific analyses. The database is constituted by CT images of 24 spruces obtained with a medical CT scanner. Studied trees are representative of several social status and are coming from four stands located in North-Eastern France, themselves are representative of several age, density and fertility classes. The automatic processing developed are the following. First, pith detection in logs dealing with the problem of knot presence and ring eccentricity. The accuracy of the localisation was less than one mm. Secondly, the detection of the sapwood/heart-wood limit in logs dealing with the problem of knot presence (main source of difficulty). The error on the diameter was 1.8 mm which corresponds to a relative error of 1.3 per cent. Thirdly, the detection of the whorls location and comparison with an optical method. Fourthly the detection of individualized knots. This process allows to count knots and to locate them in a log (longitudinal position and azimuth); however, the validation of the method and extraction of branch diameter and inclination are still to be developed. An application of this work was a variability analysis of the sapwood content in the trunk: at the within-tree level, the sapwood width was found to be constant under the living crown; at the between-tree level, a strong correlation was found with the amount of living branches. A great number of analyses are possible from our work results, among others: architectural analysis with the pith tracking and the apex death occurrence; analysis of radial variations of the heart-wood shape; analysis of the knot distribution in logs. (author)

  14. Non-destructive analysis and detection of internal characteristics of spruce logs through X computerized tomography; Detection et analyse non destructive de caracteristiques internes de billons d'epicea commun (PICEA ABIES (L.) KARST) par tomographie a rayons X

    Energy Technology Data Exchange (ETDEWEB)

    Longuetaud, F

    2005-10-15

    Computerized tomography allows a direct access to internal features of scanned logs on the basis of density and moisture content variations. The objective of this work is to assess the feasibility of an automatic detection of internal characteristics with the final aim of conducting scientific analyses. The database is constituted by CT images of 24 spruces obtained with a medical CT scanner. Studied trees are representative of several social status and are coming from four stands located in North-Eastern France, themselves are representative of several age, density and fertility classes. The automatic processing developed are the following. First, pith detection in logs dealing with the problem of knot presence and ring eccentricity. The accuracy of the localisation was less than one mm. Secondly, the detection of the sapwood/heart-wood limit in logs dealing with the problem of knot presence (main source of difficulty). The error on the diameter was 1.8 mm which corresponds to a relative error of 1.3 per cent. Thirdly, the detection of the whorls location and comparison with an optical method. Fourthly the detection of individualized knots. This process allows to count knots and to locate them in a log (longitudinal position and azimuth); however, the validation of the method and extraction of branch diameter and inclination are still to be developed. An application of this work was a variability analysis of the sapwood content in the trunk: at the within-tree level, the sapwood width was found to be constant under the living crown; at the between-tree level, a strong correlation was found with the amount of living branches. A great number of analyses are possible from our work results, among others: architectural analysis with the pith tracking and the apex death occurrence; analysis of radial variations of the heart-wood shape; analysis of the knot distribution in logs. (author)

  15. EFFECT OF BAKING ON THE PHYSICAL-CHEMICAL CHARACTERISTICS AND THE HYGIENICAL QUALITY OF BISCUITS / EFFET DE LA CUISSON SUR LES CARACTERISTIQUES PHYSICO-CHIMIQUES ET LA QUALITE SANITAIRE DES BISCUITS

    Directory of Open Access Journals (Sweden)

    MOHAMED MAMOUMI

    2012-06-01

    Full Text Available The food safety is necessary of development of agro-food industries. We opted for the introduction of a concept to ensure a sanitary control of products-wares, including the pastry. We chose for our project three parameters as: water activity (aw, pH and moisture. Also, we defined the target values for these parameters to ensure the safety of our pastry. Otherwise, we incorporated the factor temperature to ensure complete control of safety knowing that cooking is a major industry in the pastry. We defined the temperature of microbial destruction to reduce the microbial load of the pastry after baking. This study was approved by microbiological analysis carried out on the cake having undergone the following parameters (aw, pH, moisture, temperature of microbial destruction.

  16. La vitalite ethnolinguistique et les caracteristiques socio-psychologiques de l'individu vivant en milieu bilingue (Ethnolinguistic Vitality and the Socio-Psychological Characteristics of the Individual Living in a Bilingual Environment).

    Science.gov (United States)

    Labrie, Normand

    A study in Moncton, New Brunswick, of second language use by language minorities and native language maintenance as it relates to the linguistic groups' vitality and the individuals' attitudes toward these groups is reported. Seven research hypotheses were proposed: (1) The first language group's perception of the second language group's vitality…

  17. Particulate emissions from road transportation (gasoline and diesel). Chemical and granulometric characteristics; relative contribution; Emissions particulaires par les transports routiers (essence et diesel) caracteristiques chimiques et granulometriques contribution relative

    Energy Technology Data Exchange (ETDEWEB)

    Belot, G. [PSA-Peugiot-Citroen, 92 - La Garenne-Colombes (France)

    1996-12-31

    The formation process and chemical composition of diesel, leaded and lead-free gasoline combustion particulates are presented, and the effects of engine technology, post-treatments (oxidative catalysis), automobile speed and fuel type (more especially diesel type), on the granulometry of gasoline and diesel automotive particulates are studied. The emission contributions from the various diesel vehicle types (automobiles, trucks, buses), gasoline and diesel automobiles and other natural and anthropogenic particulate sources, are presented and compared

  18. EFFECT OF BAKING ON THE PHYSICAL-CHEMICAL CHARACTERISTICS AND THE HYGIENICAL QUALITY OF BISCUITS / EFFET DE LA CUISSON SUR LES CARACTERISTIQUES PHYSICO-CHIMIQUES ET LA QUALITE SANITAIRE DES BISCUITS

    OpenAIRE

    MOHAMED MAMOUMI; HANANE FIKRI; RACHID SLIMANI; HAMID AMAROUCHE; MOULAY MUSTAPHA ENNAJI; MOHAMED ZAHOUILY; SAÏD LAZAR

    2012-01-01

    The food safety is necessary of development of agro-food industries. We opted for the introduction of a concept to ensure a sanitary control of products-wares, including the pastry. We chose for our project three parameters as: water activity (aw), pH and moisture. Also, we defined the target values for these parameters to ensure the safety of our pastry. Otherwise, we incorporated the factor temperature to ensure complete control of safety knowing that cooking is a major industry in the past...

  19. Discontinuous finite element and characteristics methods for neutrons transport equation solution in heterogeneous grids; Resolution de l'equation du transport des neutrons par les methodes des elements finis discontinus et des caracteristiques structurees appliquees a des maillages heterogenes

    Energy Technology Data Exchange (ETDEWEB)

    Masiello, E

    2006-07-01

    The principal goal of this manuscript is devoted to the investigation of a new type of heterogeneous mesh adapted to the shape of the fuel pins (fuel-clad-moderator). The new heterogeneous mesh guarantees the spatial modelling of the pin-cell with a minimum of regions. Two methods are investigated for the spatial discretization of the transport equation: the discontinuous finite element method and the method of characteristics for structured cells. These methods together with the new representation of the pin-cell result in an appreciable reduction of calculation points. They allow an exact modelling of the fuel pin-cell without spatial homogenization. A new synthetic acceleration technique based on an angular multigrid is also presented for the speed up of the inner iterations. These methods are good candidates for transport calculations for a nuclear reactor core. A second objective of this work is the application of method of characteristics for non-structured geometries to the study of double heterogeneity problem. The letters is characterized by fuel material with a stochastic dispersion of heterogeneous grains, and until now was solved with a model based on collision probabilities. We propose a new statistical model based on renewal-Markovian theory, which makes possible to take into account the stochastic nature of the problem and to avoid the approximations of the collision probability model. The numerical solution of this model is guaranteed by the method of characteristics. (author)

  20. New solutions in the use of energy. Characteristics for a Mediterranean building; Nouvelles solutions dans l'utilisation de l'energie. Caracteristiques pour un batiment mediterraneen

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-07-01

    This document is edited by the regional energy agency of Provence-Alpes-Cote d'Azur region (ARENE) with the participation of the ICAEN (Institut Catala d'Energia) (Barcelona, Spain) and Punto Energia (Milan, Italy) and with the help of the general direction of energy of the European Commission (DG 17, sub-program 'Energy'). It presents the rules for the elaboration of a 'building program' devoted to foremen and which aims at integrating the energy and environmental requirements of a building prior to its construction: 1 - planning (goal, preliminary and feasibility studies); 2 - elaboration of the energy program (environmental context of the project, demand formulation: environmental impact, comfort, electricity and water uses, maintenance, costs..); 3 - characteristics of a Mediterranean building (regional aspect, envelope and passive heating/cooling techniques, active techniques), 4 - energy feasibility study; 5 - evaluation means. (J.S.)

  1. Construction and operating characteristics of flexible Geiger counters; Caracteristiques de construction et d'utilisation de compteurs Geiger flexibles; Konstruktsionnaya i operativnaya kharakteristiki gibkikh schetchikov Gejgera; Construccion y caracteristicas de funcionamiento de contadores Geiger flexibles

    Energy Technology Data Exchange (ETDEWEB)

    Richter, H G; Ballard, L F [Research Triangle Institute, Durham, NC (United States)

    1962-04-15

    A method has been developed for constructing flexible Geiger counters in a wide range of lengths and diameters. The counters are quite flexible: a 3-cm diam. counter can be bent to a circle of 5 cm radius. Using Q-gas (98.3% helium, 1.7% n-butane) as the counting medium, plateaux are several hundred volts long with 3% slopes and are independent of the counter configuration. Counters are constructed from tubing having a polyvinyl-chloride formulation (PVC-744 - Alpha Wire Corp.). Short segments of the plastic tubing (length {approx} 3 times the tube diameter) are slipped over a coarsely threaded aluminium mandrel. Wire is wrapped tightly in the threads and the whole is placed in a 110{sup o}C oven for 20 min. After cooling, the corrugated plastic segment is removed from the mandrel. This corrugation prevents the collapse of the tubing when it is coiled. A polystyrene disk, perforated with relatively large holes near the periphery for gas flow and having a 0.6-mm hole in the centre for the anode, is fastened in one end of each segment. By threading the segments thus prepared on a 3-mil tungsten anode and slipping one end of each segment over the adjacent segment and securing them with an adhesive, a counter of any desired length can be built up. Glass end-pieces for attaching the anode ends and for admitting and exhausting the flow gas are attached. A bare copper wire spiralled in the grooves of the counter makes a satisfactory external cathode which operates in the manner observed by MAZE. A 3-cm diam. counter, 1 m long, either linear or coiled, has a plateau beginning at 1400 V and extending beyond 1750 V with a 2.9% slope. Counting rates in excess of 300000 counts/min with little coincidence loss have been observed. Since the counter is actually a series of short Geiger counters and the discharge does not spread beyond the polystyrene spacer disks, adjacent counter segments operate independently. Pulse heights are greater than 50 mV. (author) [French] On a mis au point une methode de construction de compteurs Geiger flexibles ayant des dimensions tres variees. Les compteurs sont tres flexibles : un compteur de 3 cm de diametre peut etre plie avec un rayon de courbure de 5 cm. En utilisant du gaz Q (98,3% d'helium et 1,7% de n-butane) comme milieu de comptage, les paliers ont une longueur de plusieurs centaines de volts avec une pente de 3% et sont independants de la configuration geometrique du compteur. Les compteurs sont construits avec des tubes en chlorure de polyvinyle (PVC-744 - Alpha Wire Corp.). De courts segments du tube (longueur egale a environ 3 fois le diametre) sont glisses sur un mandrin d'aluminium grossierement filete et entoures d'un fil fortement serre. Le tout est place dans un four a 110{sup o}C pendant 20 minutes. Apres refroidissement, le segment de matiere plastique ainsi cannele est degage du mandrin. Ce traitement du tube empeche sa rupture lorsqu'il est enroule. Un disque de polystyrene, perfore de trous relativement grands a la peripherie pour l'ecoulement du gaz et d'un trou central de 0,6 mm pour le passage de l'anode, est attache a une extremite de chaque segment. En enfilant les segments ainsi prepares sur une anode en tungstene de 3 mm, en glissant une extremite de chaque segment sur le segment adjacent et en les fixant solidement avec un adhesif, on peut construire un compteur d'une longueur quelconque. On attache aux extremites des pieces en verre pour la fixation de l'anode et pour l'admission et l'evacuation du gaz. Un fil de cuivre nu, entoure en spirale dans les cannelures du compteur, donne une cathode externe satisfaisante, qui fonctionne suivant le mode observe par Maze. Un compteur de 3 cm de diametre et de 1 metre de longueur, lineaire ou enroule, possede un palier commencant a 1400 volts et allant jusqu'a 1700 volts avec une pente de 2,9%. On a enregistre des taux de comptage de plus de 300000 coups par minute, avec peu de pertes par coincidences. Comme le compteur est en fait une seris de compteurs Geiger courts et que la decharge ne s'etend pas au-dela des disques d'espacement en polystyrene, les segments de compteur adjacents fonctionnent independamment. Les hauteurs d'impulsions depassent 50 mV. (author) [Spanish] Los autores describen el metodo que han usado para construir contadores Geiger flexibles, de muy diferentes longitudes y diametros. Estos contadores son efectivamente muy flexibles: un contador de 3 cm de diametro puede doblarse hasta formar un circulo de 5 cm de radio. Utilizando gas Q (98,3% de helio y 1,7% de n-butano) se obtienen de varios centenares de voltios con pendientes de 3%, que son independientes de la configuracion del contador. Estos contadores estan hechos de tubos de material plastico a base de cloruro de polivinilo (PVC-744 - Alpha Wire Corp.). Sobre un mandril de aluminio de rosca gruesa se enchufan segmentos cortos de tubo de dicho material plastico (de una longitud aproximadamente 3 veces mayor que el diametro del tubo). Los filetes de la rosca se envuelven con alambre bien apretado y la pieza entera se coloca en un horno a 110{sup o}C durante 20 minutos. Despues de enfriar, el segmento de material plastico asi ondulado se retira del mandtil. Esta ondulacion evita que el tubo se aplaste cuando se le enrolla. En un extremo de cada segmento va sujeto un disco de poliestireno, en el que se han practicado orificios relativamente grandes proximos a la periferia, para permitir la circulacion del gas; el disco lleva ademas un orificio de 0,6 mm en el centro, para el anodo. Roscando los segmentos preparados en esta forma sobre un anodo de tungsteno de 3 milesimas de pulgada (75 micrones), enchufando el extremo de cada segmento sobre el segmento siguiente y sujetandolos con un material adhesivo, se puede dar al contador la longitud que se desee. Se adjuntan piezas terminales de vidrio para sujetar los extremos del anodo y para dar entrada y salida a la corriente de gas. Un alambre de cobre desnudo encajado en espiral en las ranuras del contador constituye un catodo externo satisfactorio que funciona en la forma observada por Maze. Un contador de 3 cm de diametro y 1 m de largo, por ejemplo, sea extendido o enrollado, presenta un que comienza a los 1400 V y se extiende a mas de 1750 V con una pendiente del 2,9%. Se ha contado a mas de 300000 impulsos por minuto, con escasa perdida por coincidencia : como el contador consiste practicamente en una serie de contadores Geiger cortos y la descarga no se extiende mas alla de los discos espaciadores de poliestireno, los segmentos de contador adyacentes trabajan independientemente. Las amplitudes de los impulsos superan a los 50 mV. (author) [Russian] Byl razrabotan metod izgotovleniya gibkikh schetchikov Gejgera razlichnoj dliny i diametra. Schetchiki yavlyayutsya sovershenno gibkimi; schetchik diametrom 3 cm mozhno sognut' v krug radiusom 5 cm. Pri ispol'zovanii Q-gaza (98,3% geliya i 1,7% n-butana) v kachestve schetnoj sredy, plato imeyut neskol'ko sot vol't napryazheniya s 3-protsentnym skatom i ne zavisyat ot konfiguratsii schetchika. Schetchiki izgotovleny iz plastmassovoj polivinil-khloridnoj trubki (PVC-744-Al'fa Uajr Korp.). Korotkie segmenty plastmassovoj trubki (dlina sostavlyaet primerno 3 diametra trubki) prokhodyat cherez grubo narezannyj alyuminievyj serdechnik. Provod plotno obertyvaetsya v narezkakh i vse vmeste pomeshchaetsya na 20 minut v pech' s temperaturoj 110{sup o}C. Posle okhlazhdeniya riflenyj plastmassovyj segment snimaetsya s narezki. Ehto riflenie predokhranyaet trubku ot razrusheniya pri namatyvanii. Polistirolovyj disk, perforirovannyj otnositel'no bol'shimi otverstiyami okolo okruzhnosti dlya perekhoda gaza i imeyushchij otverstie 0,6 mm v tsentre dlya anoda, krepitsya na odnom kontse kazhdogo segmenta. Natyagivaya podgotovlennye takim obrazom segmenty na vol'framovyj anod v 3 mm i propuskaya odin konets kazhdogo segmenta poverkh sosednego segmenta s odnovremennym krepleniem, mozhno sozdat' schetchik lyuboj zhelaemoj dliny. Dlya prisoedineniya kontsov anoda i dlya vpuska i vypuska potoka gaza pridayutsya steklyannye nakonechniki. Ogolennyj mednyj provod, prokhodyashchij zmeevikom v vyrezakh schetchika, predstavlyaet soboj udovletvoritel'nyj vneshnij katod, dejstvuyushchij po printsipu Mejza. Schetchik diametrom 3 cm i dlinoyu 1 m (linejnogo ili katushechnogo tipa) imeet plato, nachinaya s 1400 vol't i konchaya bolee 1750 vol't s 2,9-protsentnym skatom. Schetchik registriruet svyshe 300000 otschetov v minutu s neznachitel'noj poterej pri sovpadenii. Poskol'ku schetchik otnositsya fakticheski k serii korotkikh schetchikov Gejgera, a razryad ne vykhodit za predely polistirolovykh razdelitel'nykh diskov, to primykayushchie segmenty schetchika rabotayut nezavisimo. Amplitudy impul'sov prevyshayut 50 millivol't. (author)

  2. Structure and properties of rare earth-rich glassed for nuclear waste immobilisation; Etude des caracteristiques structurales et des proprietes de verres riches en terres rares destines au confinement des produits de fission et elements a vie longue

    Energy Technology Data Exchange (ETDEWEB)

    Bardez, I

    2004-11-15

    A new nuclear glass composition, able to immobilize highly radioactive liquid wastes from high burn-up UO{sub 2} fuel, was established and its structure studied. The composition of the selected rare earth-rich glass is (molar %): 61.79 SiO{sub 2} - 8.94 B{sub 2}O{sub 3} - 3.05 Al{sub 2}O{sub 3} - 14.41 Na{sub 2}O - 6.32 CaO - 1.89 ZrO{sub 2} - 3.60 RE{sub 2}O{sub 3} (with RE = La, Ce, Pr and Nd). The aim of this study was to determine the local environment of the rare earth in this glass and also to glean information about the effect of glass composition on the rare earth neighbouring (influence of Si, B, Al, Na and Ca contents). To this end, several series of glasses, prepared from the baseline glass, were studied by different characterisation methods such as EXAFS spectroscopy at the neodymium LIII-edge, optical absorption spectroscopy, Raman spectroscopy and {sup 29}Si, {sup 27}Al and {sup 11}B MAS-NMR. By coupling all the results obtained, several hypotheses about the nature of the rare earth neighbouring in the glass were proposed. (author)

  3. Study of the magnetic characteristics of ferrites with a view to their application in a proton synchrotron; Etudes des caracteristiques magnetiques des ferrites en vue de leur application dans un synchrotron a protons

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, K C [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1966-10-01

    In this report magnetic properties of some Ni Zn ferrites available in France are investigated for the purpose of their use in accelerating cavities of proton synchrotron. An attempt is made to measure permeability and quality factor of ferrite versus various physical parameters such as frequency F, the induction B, the magnetic bias field Hp and the temperature, the investigation ranges being: F {<=} 40 Mc/s; B {<=} 10{sup -2} Tesla; Hp {<=} 5000 AT/m; T {<=} 100 C. The measurements were carried out with the one hand, conventional impedance bridge (Q-meter, RX-meter) and on the other hand, with resonating method using an inductive ferrite loaded cavity in parallel with an external capacity. The latter method is of particular interest for the measurements in function of induction and magnetic bias field. (author) [French] Ce travail consiste a etudier les proprietes magnetiques d'un certain nombre de ferrites de Ni Zn disponibles sur le marche francais en vue de leur utilisation dans les cavites acceleratrices d'un synchrotron a protons. On se propose de mesurer la permeabilite et le facteur de qualite du ferrite en fonction de divers parametres physiques tels que la frequence F, l'induction B, le champ magnetique de polarisation Hp et la temperature T, avec: F {<=} 40 Mc/s; B {<=} 10{sup -2} Tesla; Hp {<=} 5000 AT/m; T {<=} 100 C. On effectue les mesures d'une part a l'aide des ponts d'impedance classiques (Q-metre, RX-metre) et d'autre part par la methode du resonateur qui consiste a mettre en parallele une cavite inductive chargee de ferrite et une capacite exterieure. Cette derniere methode est particulierement interessante pour les mesures en fonction de l'induction et du champ magnetique polarisant. (auteur)

  4. Photo-Induced Electron-Exchange Reactions Exhibiting Chain Characteristics; Echanges d'Electrons Photoinduits Presentant les Caracteristiques d'une Reaction en Chaine; Vyzvannye fotonami reaktsii ehlektronnogo obmena, proyavlyayushchie kharakteristiki tsepochki; Intercambio de Electrones Fotoinducido del Tipo de Cadena

    Energy Technology Data Exchange (ETDEWEB)

    Stranks, D. R.; Yandell, J. R. [University of Adelaide, Adelaide (Australia)

    1965-10-15

    The absorption of light of an appropriate wavelength can markedly accelerate the rate of a two-electron exchange reaction. Charge-transfer absorption generates an intermediate oxidation state which is responsible for propagating a chain reaction between the two stable oxidation states. The general kinetic equations for exchange systems involving chain propagation and either linear or quadratic termination are derived. It is shown that the dependence of the observed quantum yield on reactant concentrations and the absorbed light intensity is more complex than has been hitherto assumed. In principle, a kinetic investigation of such an exchange system should evaluate the primary quantum yield for the initial charge-transfer absorption process, the rates of electron transfer between each of the two stable oxidation states and the intermediate state, and the rate of disproportionation of the intermediate oxidation state. These general considerations are illustrated with the results of an experimental study of the thallium(I)- thallium(III) system. Selective charge-transfer absorption at 2537 A by the Tl{sup 3+}. OH{sup -} ion-pair is used to generate Tl{sup II}. The ensuing exchange reaction with Tl{sup +} exhibits marked induction periods and is sensitive to micromolar concentrations of oxidants and reductants. At millimolar concentrations of Tl{sup +} and Tl{sup 3+}, the observed quantum yields are directly proportional to the Tl{sup +} and Tl{sup 3+} concentrations. At higher concentrations, the quantum yields level oui to ''plateau'' values which range from 6 to 30, depending on the absorbed light intensity. The plateau quantum yield is a direct measure of the relative rates of the propagation reactions Tl{sup +} + Tl{sup 2+} -> Tl{sup 2+} + T1+ and Tl{sup 2+} + Tl{sup 3+} -> Tl{sup 3+} + Tl{sup 2+} compared to the termination reaction 2 Tl{sup 2+} -> Tl{sup +} + Tl{sup 3+}. This disproportionation reaction is consistent with a light intensity exponent of 0. 50, which may be observed in rigorously pure reactant solutions. However, in solutions containing micromolar concentrations of impurities, this exponent can rise to 0.70 owing to the importance of the scavenging reaction Tl{sup 2}+ + S ->Tl{sup +} (or Tl{sup 3+}) + S'. The short lifetime of Tl{sup 2+} (probably milliseconds) has so far prevented the measurement of the rate of the Tl{sup 2+} disproportionation reaction by rotating sector techniques. The relative rates of these electron-transfer reactions are discussed in terms of electron-tunnelling theories. The observed primary quantum yield for the reaction Tl{sup 3+}. OH{sup -} + hv -> Tl{sup 2+} + OH is shown to be consistent with the Noyes theory of diffusion of geminate radicals. (author) [French] L'absorption d'une lumiere de longueur d'onde appropriee peut considerablement accelerer la vitesse d'un echange deux electrons. L'absorption avec transfert de charges produit un etat d'oxydation intermediaire auquel est due la propagation d'une reaction en chaine entre les deux etats d'oxydation stables. Les auteurs etablissent les equations cinetiques generales pour les systemes d'echange impliquant une propagation en chaine et une terminaison soit lineaire soit quadratique. Ils demontrent que la relation de dependance entre le rendement quantique observe, d'une part, et les concentrations en corps reagissants et l'intensite de la lumiere absorbee, d'autre part, est plus complexe que dans l'hypothese admise jusqu'ici. En principe, une etude cinetique portant sur un tel systeme d'echange devrait tendrea evaluer le rendement quantique primaire pour le processus d'absorption initial avec transfert de charge, les vitesses du transfert d'electrons entre chacun des deux etats d'oxydation stables et l'etat intermediaire, ainsi que la vitesse de dismutation de l'etat d'oxydation intermediaire. Ces considerations generales sont illustrees par les resultats d'une etude experimentale sur le systeme Tl{sup I}-Tl{sup III}. Pour produire Tl{sup II}, les auteurs ont utilise une absorption selective avec transfert de charges a 2537 A au moyen de la paire d'ions Tl{sup 3+}. OH{sup -}. L'echange avec Tl{sup +} qui s'ensuit presente des periodes d'induction bien marquees; il est sensible aux concentrations micromolaires en oxydants et en reducteurs. Pour des concentrations millimolaires en Tl{sup +} et Tl{sup 3+} , les rendements quantiques observes sont directement proportionnels ie ces concentrations. Pour de plus fortes concentrations, la courbe des valeurs du rendement quantique presente un plateau dont le niveau se situe entre 6 et 30, selon l'intensite de la lumiere absorbee, La valeur de plateau du rendement quantique constitue une mesure directe des vitesses relatives des reactions de propagation Tl{sup +} + Tl{sup 2+} -> Tl{sup 2+} + T1+ and Tl{sup 2+} + Tl{sup 3+} -> Tl{sup 3+} + Tl{sup 2+} comparees ie la reaction de terminaison 2 Tl{sup 2+} -> Tl{sup +} + Tl{sup 3+}. Cette reaction de dismutation est compatible avec un exposant de 0,50 pour l'intensite de la lumiere, que l'on peut observer dans des solutions rigoureusement pures des corps en reaction. Toutefois, dans les solutions contenant des concentrations micromolaires d'impuretes, cet exposant peut aller jusqu'a 0,70 en raison de l'importance de la reaction de balayage Tl{sup 2}+ + S ->Tl{sup +} (or Tl{sup 3+}) + S'. Jusqu'a present, la courte duree de vie de Tl{sup 2+} (qui se mesure probablement millisecondes) n'a pas permis de mesurer la vitesse de la reaction de dismutation de Tl{sup 2+} par les methodes des secteurs en rotation. Les auteurs discutent les vitesses relatives de ces echanges par transfert d'electrons en invoquant des theories fondees sur l'effet tunnel. Ils montrent que le rendement quantique primaire observe pour la reaction Tl{sup 3+}. OH{sup -} + hv -> Tl{sup 2+} + OH est compatible avec la theorie de Noyes sur la diffusion de radicaux gemines. (author) [Spanish] La absorcion de luz de una longitud de onda determinada puede acelerar sensiblemente la velocidad de una reaccion de intercambio en que participen dos electrones. La absorcion por transferencia de carga origina en estado de oxidacion intermedio como consecuencia del cual se propaga una reaccion en cadena entre los dos estados estables de oxidacion. Los autores deducen las ecuaciones cineticas generales para sistemas de intercambio con propagacion en cadena y terminacion lineal o cuadratica. Demuestran que las relaciones de dependencia entre el rendimiento cuantico observado por una parte y la concentracion de las sustancias que entran en reaccion, y la intensidad de la luz absorbida por la otra es mas compleja que lo que se suponia. En principio, el estudio cinetico de un sistema de intercambio de este tipo deberia tener por objetivo evaluar el rendimiento cuantico primario correspondiente al proceso inicial de absorcion por transferencia de carga, la velocidad de transferencia de electrones entre cada uno de los dos estados estables de oxidacion y el estado intermedio, y la velocidad de dismutacion del estado de oxidacion intermedio. Estas consideraciones generales se ilustran con los resultados de un estudio experimental del sistema talio(I)-talio(III). Se utiliza la absorcion selectiva por transferencia de carga a 2537 A por el par ionico TI{sup 3+}. OH- para producir TI{sup II}. La reaccion de intercambio que seguidamente tiene lugar con el Tl{sup +} presenta claros periodos de induccion y es sensible a concentraciones micromolares de oxidantes y reductores. A concentraciones milimolares de Tl{sup +} y TI{sup 3+} , los rendimientos cuanticos observados son directamente proporcionales a la concentracion de TI{sup +} y TI{sup 3+}, mientras que a concentraciones mas elevadas, los rendimientos cuanticos se estabilizan en torno a valores que oscilan entre 6 y 30, segun la intensidad de la luz absorbida. Estos valores estables del rendimiento cuantico constituyen una media directa de las velocidades relativas delas reacciones de propagacion Tl{sup +} + Tl{sup 2+} -> Tl{sup 2+} + T1+ and Tl{sup 2+} + Tl{sup 3+} -> Tl{sup 3+} + Tl{sup 2+} referidas a la reaccion de terminacion 2 Tl{sup 2+} -> Tl{sup +} + Tl{sup 3+}. Esta reaccion de dismutacion es compatible con un exponente de 0,50 para la intensidad . de la luz, que puede observarse en soluciones de reactivos sumamente puros. Sin embargo, en las soluciones con concentraciones micromolares de impurezas, dicho exponente puede aumentar a 0,70 debido a la importancia de la reaccion de depuracion. Tl{sup 2}+ + S ->Tl{sup +} (or Tl{sup 3+}) + S'. El corto periodo de vida del TI{sup 2+} (probablemente del orden de los milisegundos) ha impedido hasta ahora medir la velocidad de'la reaccion de dismutacion del Tl + por el metodo del sector rotativo. Las velocidades relativas de estas reacciones de intercambio electronico se examinan aplicando la teoria del efecto tunel electronico. Se demuestra que el rendimiento cuantico primario observado en el caso de la reaccion Tl{sup 3+}. OH{sup -} + hv -> Tl{sup 2+} + OH es compatible con la teoria de difusion de radicales geminados de Noyes. (author) [Russian] Pogloshhenie sveta opredelennoj dliny volny mozhet zametno uvelichit' skorost' protekanija reakcii obmena dvuh jelektronov. Pogloshhenie perenosa za- rjada porozhdaet sostojanie promezhutochnogo okislenija, kotoroe privodit k rasprostraneniju cepnoj reakcii mezhdu dvumja ustojchivymi sostojanijami okislenija. Vyvodjatsja obshhie kineticheskie uravnenija dlja sistem obmena, svjazannye s rasprostra- neniem cepochki i libo linejnym, libo kvadratichnym prekrashheniem. Pokazyvaetsja, chto zavisimost' otmechaemogo vyhoda kvanta ot koncentracij reagentov i intensivnosti po- gloshhennogo sveta javljaetsja bolee slozhnoj, chem jeto predpolagalos' ranee. V principe v rezul'tate izuchenija kinetiki takoj sistemy obmena mozhno ocenit' vyhod pervichnogo kvanta dlja pervonachal'nogo processa pogloshhenija perenosa zarjada, opredelit' skorosti perenosa jelektronov mezhdu kazhdym iz dvuh ustojchivyh sostojanij okislenija i promezhutochnym sostojaniem i skorost' disproporcionirovanija promezhutochnogo sostojanija okislenija. Jeti obshhie soobrazhenija illjustrirujutsja rezul'tatami jeksperimental'nogo izuchenija sistemy talij (I) - talij (III). Izbiratel'noe pogloshhenie perenosa zarjada paroj ionov T Script-Small-L {sup 3+} ON{sup -} pri 2537 A ispol'zuetsja dlja obrazovanija T Script-Small-L {sup II}. V posledujushhej reakcii obmena s Tit' projavljajutsja zametnye periody indukcii i chuvstvitel'nost' k mikromoljarnym kon- centracijam okislitelej i vosstanovitelej. Pri millimoljarnyh koncentracijah T Script-Small-L {sup +} i T Script-Small-L {sup 3+} nabljudaemye vyhody kvantov nahodjatsja v projamoj proporcional'noj zavisimosti ot kon- centracij T Script-Small-L {sup +} i T Script-Small-L {sup 3+} . Pri povyshennyh koncentracijah uroven' vyhodov kvantov sravnivaetsja so znachenijami {sup p}lato{sup ,} kotorye kolebljutsja v diapazone ot 6 do 30, v zavisimosti ot in- tensivnosti pogloshhennogo sveta. Vyhod kvanta na plato javljaetsja neposredstvennym merilom otnositel'nyh skorostej reakcij rasprostranenija T Script-Small-L {sup +} + T Script-Small-L {sup 2+} -> T Script-Small-L {sup 2+} + T1+ and T Script-Small-L {sup 2+} + T Script-Small-L {sup 3+} -> T Script-Small-L {sup 3+} + T Script-Small-L {sup 2+} po sravneniju s reakciej obryva cepi 2 T Script-Small-L {sup 2+} -> T Script-Small-L {sup +} + T Script-Small-L {sup 3+}. Jeta reakcija dispro- porcionirovanija javljaetsja sovmestimoj s jeksponentoj 0,50 intensivnosti sveta, kotoruju mozhno nabljudat' v strogo chistyh rastvorah reagirujushhego veshhestva. Odnako v rastvorah, v kotoryh imejutsja mikromoljarnye koncentracii primesej, jeta jeksponenta mozhet podnimat'sja do 0,70 vvidu vazhnosti reakcii ochistki T Script-Small-L {sup 2}+ + S ->T Script-Small-L {sup +} (or T Script-Small-L {sup 3+}) + S'. V svjazi s korotkim periodom zhizni T Script-Small-L {sup 2+} (verojatno, porjadka millisekund) do sih por ne udalos' izmerit' sko- rost' reakcii disproporcionirovanija T Script-Small-L {sup 2+} metodom vrashhajushhegosja sektora. Otnositel'nye skorosti jetih reakcij perenosa jelektronov obsuzhdajutsja v ramkah teorij tunnel'nogo jeffekta jelektronov. Pokazyvaetsja, chto nabljudaemyj vyhod pervichnyh kvantov dlja reakcii T Script-Small-L {sup 3+}. OH{sup -} + hv -> T Script-Small-L {sup 2+} + OH sovmestim s teoriej Nojesa otnositel'no diffuzii radikalov geminata. (author)

  5. Comparative study of the characteristics of some suction devices for gas sampling applications; Etude comparative des caracteristiques de quelques dispositifs d'aspiration a l'usage des prelevements de gaz

    Energy Technology Data Exchange (ETDEWEB)

    Donguy, R.; Drouet, J.

    1959-06-15

    Gas sampling (used to determine the characteristics of dusts or aerosols contained in a gas) needs a suction device. In order to select the right device and the right conditions of use, the characteristics and performances of various suction devices (helicoidal and centrifugal aspirators, air pumps, volumetric pumps) have been experimentally measured: flow rate, head loss, sampling volume and duration, aerosol and dust concentration, gas density, nature of the gas, suction circuit configuration, etc.

  6. Study of potential of nuclear waste transmutation and safety characteristics of an hybrid system: sub critical accelerator reactor; Etude du potentiel de transmutation et des caracteristiques de surete d`un systeme hybride: accelerateur reacteur sous critique

    Energy Technology Data Exchange (ETDEWEB)

    Tchistiakov, A

    1998-04-01

    The study of potential of nuclear waste transmutation for the new reactor systems - hybrid reactors - was the object of this work. Global review of different projects is presented. The basic physical parameters definitions, as neutron surplus and relative importance of external source neutrons, are introduced and explained. For these parameters, numerical values are obtained. The advantage in neutron surplus of fast system is noted. Equilibrium model and corresponding toxicities of different isotopes nd nuclear cycles are presented. Numerical analysis for equilibrium model converge validation are performed also. The study of neutron consumption by `transmutable` Long-Lived Fission Products (Tc, I and Cs) show the possibility of their incineration in dedicated fast hybrid reactors. Equilibrium model shown the influence of reprocessing losses level to cycle toxicity level. Relations between specific fuel inventories (mass normalised by power unit) for thermal and fast spectra are examined. The differences are relatively small. Finally, few hybrid reactor concepts with different objects were analysed. These studies confirm that in frameworks of certain Nuclear Energy scenarios the fast hybrid systems can reduce significantly the radio-toxicity of fuel cycle. Preliminary analyses of sub-critical reactor behaviour show big potential of this reactor type in `Transient of Power` kind of accident, even if more detailed study is necessary. (author)

  7. Discontinuous finite element and characteristics methods for neutrons transport equation solution in heterogeneous grids; Resolution de l'equation du transport des neutrons par les methodes des elements finis discontinus et des caracteristiques structurees appliquees a des maillages heterogenes

    Energy Technology Data Exchange (ETDEWEB)

    Masiello, E

    2006-07-01

    The principal goal of this manuscript is devoted to the investigation of a new type of heterogeneous mesh adapted to the shape of the fuel pins (fuel-clad-moderator). The new heterogeneous mesh guarantees the spatial modelling of the pin-cell with a minimum of regions. Two methods are investigated for the spatial discretization of the transport equation: the discontinuous finite element method and the method of characteristics for structured cells. These methods together with the new representation of the pin-cell result in an appreciable reduction of calculation points. They allow an exact modelling of the fuel pin-cell without spatial homogenization. A new synthetic acceleration technique based on an angular multigrid is also presented for the speed up of the inner iterations. These methods are good candidates for transport calculations for a nuclear reactor core. A second objective of this work is the application of method of characteristics for non-structured geometries to the study of double heterogeneity problem. The letters is characterized by fuel material with a stochastic dispersion of heterogeneous grains, and until now was solved with a model based on collision probabilities. We propose a new statistical model based on renewal-Markovian theory, which makes possible to take into account the stochastic nature of the problem and to avoid the approximations of the collision probability model. The numerical solution of this model is guaranteed by the method of characteristics. (author)

  8. Fabrication de transistors mono-electroniques en silicium pour le traitement classique et quantique de l'information: une approche nanodamascene

    Science.gov (United States)

    Harvey-Collard, Patrick

    temperature et demontrent du blocage de Coulomb avec une energie de charge de plus de 100 meV, soit quatre fois la temperature ambiante. De plus, le regime a un seul electron et les effets quantiques du confinement dans ce regime sont observes. Pour la premiere fois, le gap complet du silicium et les premiers diamants sont mesures sur un dispositif fabrique avec un procede reproductible et industrialisable. Le diamant central voit son energie d'addition augmentee de la valeur du gap du silicium, pour un total de plus de 1200 meV, soit 46 fois la temperature ambiante. Cette caracteristique pourrait ouvrir la porte a des applications en logique basse puissance dans un mode de transport a plusieurs electrons laissant circuler dix fois plus de courant dans l'etat ouvert, tout en conservant le bas courant dans l'etat ferme d'un SET. Mots clefs : transistor mono-electronique, silicium, operation a temperature ambiante, logique basse puissance, informatique quantique, nanoelectronique, polissage chimico-mecanique, gravure plasma, nanofabrication.

  9. Evaluation experimentale et theorique du comportement a la flexion de nouveaux poteaux en materiaux composites

    Science.gov (United States)

    Metiche, Slimane

    entre ces proprietes est due au nombre de couches utilisees dans chaque zone ainsi qu'a l'orientation des fibres de chaque couche. Un total de vingt-trois prototypes de dimensions differentes; ont ete testes en flexion jusqu'a la rupture. Deux types de fibres de verre de masses lineaires differentes, ont ete utilisees afin d'evaluer l'effet du type de fibres sur le comportement a la flexion. Un nouveau montage experimental permettant de tester tous les types de poteaux en PRF a ete dimensionne et fabrique selon les recommandations decrites dans les normes ASTM D 4923-01 et ANSI C 136.20-2005. Un modele analytique base sur la theorie des poutres en elasticite lineaire est propose dans cette these. Ce modele predit avec une bonne precision le comportement experimental charge---deflexion ainsi que la deflexion maximale au sommet des poteaux en PRF; constitues de plusieurs zones de caracteristiques geometriques et mecaniques differentes. Une procedure de dimensionnement des poteaux en PRF, basee sur les resultats experimentaux obtenus dans le cadre de la presente these, est egalement proposee. Les resultats obtenus dans le cadre de la presente these permettront le developpement et l'amelioration des regles de conception utiles et pratiques a l'usage des concepteurs et des industriels du domaine des poteaux en PRF. Les retombees de cette recherche sont a la fois economiques et technologiques, car les resultats obtenus constitueront une banque de donnees qui contribueront au developpement des normes de calcul, et par consequent a l'optimisation des materiaux utilises, et serviront a valider de futurs resultats et modeles theoriques.

  10. Mechanical behaviour and rupture in clayey rocks studied by x-ray micro tomography; Comportement mecanique et rupture dans les roches argileuses etudies par micro tomographie a rayons X

    Energy Technology Data Exchange (ETDEWEB)

    Lenoir, N

    2006-03-15

    Within the framework of feasibility studies of underground repositories for radioactive waste, the study of permeability evolution with damage of the host layer is crucial. The goals of this work were: (i) to characterize experimentally the damage of two clayey rocks (BEAUCAIRE MARL and EAST SHALE) with x-ray micro tomography, (ii) to develop a high pressure triaxial set-up adapted to permeability measurement on very low permeability rocks.A number of original triaxial devices have been realised to characterize damage of clayey rocks, under deviatoric loading, with x-ray micro tomography on a synchrotron beamline at the ESRF (Grenoble). Localized damage and its evolution have been characterized at a fine scale (of order of ten microns). Digital image correlation techniques, extended to 3d images, have been used to measure incremental strain fields from tomographic images. we demonstrated that these techniques are very useful in the study of the localized damage of geo-materials and especially for the initiation. A high pressure triaxial device has been realised to measure permeability evolution of the east shale as a function of applied stress (isotropic and deviatoric). The particularity of this set-up is the small size of the test specimen (cylinder of 10 mm in diameter and 20 mm in height) which allows significant reduction of test duration. (author)

  11. High temperature oxidation of metals: vacancy injection and consequences on the mechanical properties; Consequences de l'oxydation haute temperature sur l'injection de defauts et le comportement mecanique des materiaux metalliques

    Energy Technology Data Exchange (ETDEWEB)

    Perusin, S

    2004-11-15

    The aim of this work is to account for the effects of the high temperature oxidation of metals on their microstructure and their mechanical properties. 'Model' materials like pure nickel, pure iron and the Ni-20Cr alloy are studied. Nickel foils have been oxidised at 1000 C on one side only in laboratory air, the other side being protected from oxidation by a reducing atmosphere. After the oxidation treatment, the unoxidized face was carefully examined by using an Atomic Force Microscope (AFM). Grain boundaries grooves were characterised and their depth were compared to the ones obtained on the same sample heat treated in the reducing atmosphere during the same time. They are found to be much deeper in the case of the single side oxidised samples. It is shown that this additional grooving is directly linked to the growth of the oxide scale on the opposite side and that it can be explained by the diffusion of the vacancies produced at the oxide scale - metal interface, across the entire sample through grain boundaries. Moreover, the comparison between single side oxidised samples and samples oxidised on both sides points out that voids in grain boundaries are only observed in this latter case proving the vacancies condensation in the metal when the two faces are oxidised. The role of the carbon content and the sample's geometry on this phenomenon is examined in detail. The diffusion of vacancies is coupled with the transport of oxygen so that a mechanism of oxygen transport by vacancies is suggested. The tensile tests realised at room temperature on nickel foils (bamboo microstructure) show that the oxide scale can constitute a barrier to the emergence of dislocations at the metal surface. Finally, the Ni-20Cr alloy is tested in tensile and creep tests between 25 and 825 C in oxidising or reducing atmospheres. (author)

  12. Study of the mechanical stability of superconducting cavities and stiffening of these cavities by copper coating performed with thermal spray techniques; Etudes de la stabilite mecanique des cavites supraconductrices et de la methode de rigidification par projection thermique de cuivre

    Energy Technology Data Exchange (ETDEWEB)

    Gassot, H

    2001-12-01

    Today's research in nuclear physics and in particle physics needs high energy or high intensity accelerators; the use of superconducting cavities constitutes a very important technological advance for the design of such facilities, allowing high accelerating gradient with few dissipation. One of the major problems is the frequency shift under Lorentz forces: since the quality factor of the superconducting cavities is much higher than the external factor depending on the beam charge, their bandwidths are very narrow (several Hertz). Even very small mechanical deformations under Lorentz forces could induce a frequency shift which exceeds the bandwidth when the accelerating gradient becomes very high. The contribution of this thesis consists at first in a numerical analysis of this problem, then in a mechanical study of a new method for stiffening superconducting cavities: a copper coating over their external surface by thermal spray techniques. As it was a new experiment, the choice of the process and the optimization of the parameters have been carried out. An important part of this thesis has been dedicated to the systematic mechanical characterizations of the copper coatings since they are indispensable for the evaluation of the stiffening efficiency, some links between copper coating properties and thermal projection parameters have been established. The mechanical calculations are a prerequisite to obtain an effective reduction of mechanical deformations under Lorentz forces: they permit to localize the maximum deformations, to find the ideal position and the optimised shape of the stiffener. The methods implemented in this thesis allow to compare the different kinds of coating design and then to propose an interesting solution. Finally, an original approach concerning the frequency shift in pulsed mode has been developed recently, allowing to interpret some experimental observations. (author)

  13. Thermal and mechanical behaviour of an experimental mock-up of a nuclear containment; Comportement thermique et mecanique d'une maquette experimentale d'enceinte de confinement nucleaire

    Energy Technology Data Exchange (ETDEWEB)

    Chauvel, D. [Electricite de France (EDF/SEPTEN), 69 - Villeurbanne (France); Barre, F. [Coyne et Bellier, 92 - Gennevilliers (France)

    2007-07-01

    In order to better understand the behaviour of a reactor containment submitted to combined pressure and temperature loads by means of studies of the concrete permeability and the state of cracking evolution, EDF and its French partners have built a prestressed concrete test model which represents a PWR containment typical section. The monitoring system was designed to follow the evolution of strains, temperature and state of cracking of the concrete wall from construction stage to air and steam tests. The measurements results as well as their comparison with theoretical laws or data and calculated values, allow to determine the main thermal and mechanical characteristics of the concrete, to analyse the thermo-mechanical behaviour of the structure and also to check the design criteria of prestressed concrete containments. (authors)

  14. Unique effect of mechanical crushing on the electrochemical intercalation of lithium in carbons of different morphologies; Effet unique du broyage mecanique sur l`intercalation electrochimique du lithium dans des carbones de morphologies differentes

    Energy Technology Data Exchange (ETDEWEB)

    Salver-Disma, F.; Tarascon, J.M. [Universite de Picardie, 80 - Amiens (France)

    1996-12-31

    Lithium ion batteries use an oxide as a positive electrode and a carbon material as a negative electrode. The performances of carbon electrodes have rapidly evolved during the last years thanks to the substitution of soft carbons of Conoco or MCMB-2510 type by graphites (F-399, MCMB-2528) and then by hard carbons. These high capacity carbons (700 mAh/g) have higher service life and volume capacity than graphites but their irreversible losses are greater (>20%). In this work, materials with similar electrochemical performances are prepared by mechanical crushing. Mechanical crushing allows to obtain a wide range of carbon materials with various morphologies, specific surfaces and levels of disorder. The formation of the passivation film is directly linked with the surface of materials. A reaction scheme of the reversible and irreversible capacities has been defined and has permitted to obtain compounds with reversible capacities of 720 mAh/g (2 lithium for 6 carbon). (J.S.)

  15. Coupling of a discrete ordinate 3-D radiant heat transfer model with the PHOENICS fluid mechanics software; Couplage d`un modele radiatif tridimensionnel aux ordonnees discretes au logiciel de mecanique des fluides phoenics

    Energy Technology Data Exchange (ETDEWEB)

    Muller, J [IRSID, Institut de Recherches Siderurgie, 57 - Maizieres-les-Metz (France)

    1997-12-31

    Radiant heat transfer is the main solution retained in many iron and steel metallurgy installations (re-heating and annealing furnaces etc..). Today, it has become important to dispose of performing radiant heat transfer models in heat transfer and fluid mechanics simulation softwares, and well adapted to multidimensional industrial problems. This work presents the discrete ordinate radiant heat transfer model developed at the IRSID (the French institute of research in iron and steel metallurgy) and coupled with the PHOENICS heat transfer-fluid mechanics software. Three modeling approaches are presented concerning the radiative properties of gases (H{sub 2}O-CO{sub 2}). A ``weighted grey gases sum`` model gives satisfactory results for several 1-D validation cases. (J.S.) 20 refs.

  16. Mechanical and microstructural behaviour of alumina-zirconia ceramic filaments for high temperature applications; Comportement mecanique et microstructure de filaments ceramiques alumine-zircone pour applications a haute temperature

    Energy Technology Data Exchange (ETDEWEB)

    Poulon-Quintin, A

    2002-04-01

    This thesis is a contribution to the development and to the study of two-phase alumina-zirconia ceramic filaments resistant to creep and chemical and microstructural degradation. The materials studied are experimental two-phase filaments (diameter of few millimeters) with a fibrillary structure obtained by coextrusion of sol-gels or of powder pastes and a nanocrystalline fiber of thin diameter (11{mu}m) with a homogeneous structure. They have been respectively perfected and chosen for their very promising microstructures and compositions concerning the creep resistance. This study is concentrated on the mechanical characterization at high temperature of these materials and especially on the understanding of the deformation and rupture mechanisms in relation with the microstructural evolution. The commercial fiber (Nextel 650) is a {alpha} alumina (grain size {>=}0.1{mu}m) in which the grains of the second phase zirconia are dispersed in a homogeneous way in intra (5-10 nm) as in inter-granular (20-30 nm). After a heat treatment at temperatures superior to 1200 C, it can be noted a strong grains growth preferentially to the axis of the fiber. The tensile properties decrease to a considerable extent with high temperatures ({>=}1000 C). The creep behaviour has been determined between 1000 and 1300 C (value of 2.5 for the stress exponent and of 850 kJ/mol for the activation energy). The evolution of the microstructure to a long grains microstructure is favourable for the creep resistance. A comparison with other fibers of compositions near the Nextel 650 fiber show that the Nextel 650 fiber has interesting properties for being used at high temperatures (until 1200 C). The study of co-extruded alumina-zirconia filaments with a fibrillary structure has at first required those of filaments which composition are each of the phases obtained from pastes (powder-thermoplastics or sol-gels). The composition of each of the phases has been optimized in order to adapt the rheology of the two pastes and to obtain after co-extrusion and sintering, a material presenting the less of defects possible ( porosity, cracks..). The microstructure of the different filaments (two-phase or not) has been observed to explain the consequences of the multi-extrusion on the microstructure (phases alignment, grains size and orientation). A particular attention has been dealt with the study of interfaces between the fibrilla of the different phases of the co-extruded material. It has revealed crystallographic orientation relations between the juxtaposed grains of each phases. These strong interfaces are responsible of the non division of the cracks. By tensile tests (4-points), we show at 1300 C, a decrease of the mechanical properties (two-phase or non material). In creep at 1300 C, the co-extruded filaments present creep rates superior to those of the {alpha} alumina mono-filaments. The predominant role of the {alpha} alumina and those of the strong interfaces has been revealed with the creep study. (O.M.)

  17. Modelling of the mechanical behaviour and damage of clay-stones: application to the East argillite; Modelisation du comportement mecanique des argiles raides avec prise en compte de l'endommagement: application aux argilites de l'Est

    Energy Technology Data Exchange (ETDEWEB)

    Aublive-Conil, N

    2003-03-15

    The storage in deep geological formation is one of the solutions retained by France for the management of highly long life radioactive waste. The retained host rock is a clay-stone named East argillite located in the departments of Meuse and Haute-Marne. A thermodynamic formulation is used to propose a rheological model, which reproduces the mechanical behavior of clay-stones. Initially, an anisotropic damage plastic model was formulated in order to describe material degradations. Then, the damage plastic model is reformulated in order to taken into account the damage influence on the hydraulic behavior of porous material. The numerical simulations correctly reproduce the mechanical behavior of East Argillites but also the anisotropy of the hydraulic behavior introduced by the damage effect. (author)

  18. Coupled effects of the precipitation of secondary species on the mechanical behaviour and chemical degradation of concretes; Les effets couples de la precipitation d'especes secondaires sur le comportement mecanique et la degradation chimique des betons

    Energy Technology Data Exchange (ETDEWEB)

    Planel, D

    2002-06-01

    Sulfate attack of cement-based materials remains an important problem for the durability assessment of containers and disposal engineering barriers dedicated to the long-term storage of radioactive wastes since underground water which may reach these elements contains small quantities of sulfates (7-31 mmol/1). This work contributes to the study of sulfate-induced damage mechanisms, to their understanding and modelling. The experimental phases of this study aimed at the understanding of the different physico-chemical phenomena involved during an external sulfate attack at following their evolution and their impact on the transport and mechanical properties of the material. Leaching experiments in pure water and in a solution of sodium sulfate (with a sulfate content of 15 mmol/1), have been performed simultaneously on OPC paste (w/c 0,4)in order to allow a comparison of test results. The frequent analysis of the leachant has shown a consumption of sulfate ions by the matrix, proportional to the square rate of time. The use of X-Ray Diffraction on powders, obtained by scraping the calcium-depleted part of the samples, led a precise view of the cement paste mineralogy, during sulfate attack. The use of Scanning Electron Microscopy (SEM) and Energy Dispersive Spectrometer (EDS) confirmed the correctness of XRD profiles and brought important informations concerning cracking distribution and localisation. In addition, a visual monitoring of crack appearance and evolution completed the previous observations. Based on these experimental results, a simplified model accounting for the chemical degradation of cement paste in sulfated water has been proposed. A geochemical code, coupling the chemistry in solution with the reactive transport in porous media has been used for this purpose. The model accounts for the evolution of transport properties (diffusivity) associated with the calcium-depleting of the cement matrix and the precipitation of secondary phases (gypsum, ettringite) in the porous space. The results of the reactive transport calculations have then been used to model the mechanical behaviour of the samples subjected to a sulfate attack. The constitutive mechanical model used in this study, is based on physical concepts like the generation of internal auto-stresses in concrete, induced by the precipitation of secondary phases in the porous space. It accounts for anisotropic damage and assumes that cracking can appear depending on several thresholds associated with the behaviour of the material in tension, compression and related to internal stresses originating from secondary phases precipitation. (author)

  19. Contribution to the study of the amorphization mechanisms of intermetallic compounds by mechanical grinding; Contribution a l`etude des mecanismes d`amorphisation par sollicitation mecanique de composes intermetalliques

    Energy Technology Data Exchange (ETDEWEB)

    Galy, D

    1995-01-11

    This work aims at identifying the mechanisms responsible for amorphization of NiZr and NiZr{sub 2} compounds under ball-milling. In the first part, the effect of a localized deformation is studied: the deformation is produced by indentation on bulk samples, very high local strains can be achieved by this technique. The resulting microstructure is studied by transmission electron microscopy (TEM). No evidence for amorphization is found in these compounds, contrary to what is known to occur in silicon and germanium. Despite of their high brittleness, the NiZr and NiZr{sub 2} compounds accommodate the multiaxial localized stress by plastic deformation: dislocations multiplication and glide, micro-twinning. Dislocations (both perfect and imperfect) and micro-twins have been analysed into details for the first time. The twinning mechanism in NiZr{sub 2} has been elucidated. In the second part of this work, the microstructure of NiZr{sub 2} in the course of amorphization by ball-milling is studied by TEM observation are prepared by ultra-microtomy. The following evolution is observed: first, the material is fragmented and plastically deformed; the microstructure is refined by polygonation. Second, aggregates are formed by a fragmentation and sticking process, leading to a stationary size for the aggregates. The aggregates themselves are made of a mixture of nanocrystalline (about 10 nm) material and coarser crystallites. As milling proceeds, the latter disappear to the benefit of the former. Once aggregates are 100% nanocrystalline, the amorphous phase appears and develops to the expense of the nanocrystalline phase. At late stages, small crystallites embedded in an amorphous matrix are observed. No massive chemical disordering is observed but a small amount can not be ruled out. It is suggested that amorphization occurs by chemical disordering at interfaces, induced by shear waves. (Author). 76 refs., 57 figs., 12 tabs.

  20. Coupling of a discrete ordinate 3-D radiant heat transfer model with the PHOENICS fluid mechanics software; Couplage d`un modele radiatif tridimensionnel aux ordonnees discretes au logiciel de mecanique des fluides phoenics

    Energy Technology Data Exchange (ETDEWEB)

    Muller, J. [IRSID, Institut de Recherches Siderurgie, 57 - Maizieres-les-Metz (France)

    1996-12-31

    Radiant heat transfer is the main solution retained in many iron and steel metallurgy installations (re-heating and annealing furnaces etc..). Today, it has become important to dispose of performing radiant heat transfer models in heat transfer and fluid mechanics simulation softwares, and well adapted to multidimensional industrial problems. This work presents the discrete ordinate radiant heat transfer model developed at the IRSID (the French institute of research in iron and steel metallurgy) and coupled with the PHOENICS heat transfer-fluid mechanics software. Three modeling approaches are presented concerning the radiative properties of gases (H{sub 2}O-CO{sub 2}). A ``weighted grey gases sum`` model gives satisfactory results for several 1-D validation cases. (J.S.) 20 refs.

  1. Model of mechanical representation of the formation of natural fractures inside a petroleum reservoir; Modele de representation mecanique de la formation des fractures naturelles d'un reservoir petrolier

    Energy Technology Data Exchange (ETDEWEB)

    Picard, D.

    2005-09-15

    The optimisation of the oil production requires a better characterisation of naturally fractured reservoirs. We consider and analyse two spatial distributions. One with systematic joints is arranged in an homogeneous way; joint spacing is linked to individual bedding thickness with propagation frequently interrupted by stratigraphic interfaces (single layer jointing). The second, so-called fracture swarms, consists in fractures clustering, where stratigraphic interfaces seem to play a minor role. The analysis is based on the singularity theory and matched asymptotic expansions method with a fine scale for local perturbations and a global one for general trends. We examine the conditions of fracture propagation that are determined herein using simultaneously two fracture criteria an energy and a stress condition. We consider two modes of loading. Usually, the joint (crack opening mode) and fracture swarm growths are explained by a first order phenomenon involving effective traction orthogonal to fracture plane. Although commonly used, this hypothesis seems unrealistic in many circumstances and may conflict with geological observations. Then, we try to describe fracture growth as a second order phenomena resulting from crack parallel compression. As far as propagation across layer interfaces is concerned, the effect of loading and geometry has been summarised in maps of fracture mechanisms, describing areas of 'step-over', 'straight through propagation' and 'crack arrest'. Fracture criteria, relative size of heterogeneities, contrast of mechanical properties between bed and layer are parameters of the problem. For fracture swarms, we present a discussion bringing out what is reasonable as a loading to justify their morphology. In particular, horizontal effective tension is unable to explain neighbouring joints. Simultaneous propagation of parallel near cracks is explained by finite width cracks growing under the influence of vertical loading. Steady state behaviour is discussed, processes justifying a stationary growth are compared to those including an initiation step followed by a transient process at the crack tip (involving chemistry for instance). (author)

  2. Mechanical behaviour of nickel foams: three-dimensional morphology, non-linear models and fracture; Caracterisation et simulation numerique du comportement mecanique des mousses de nickel: morphologie tridimensionnelle, reponse elastoplastique et rupture

    Energy Technology Data Exchange (ETDEWEB)

    Dillard, Th.

    2004-03-15

    The deformation behaviour and failure of nickel foams were studied during loading by using X-ray microtomography. Strut alignment and stretching are observed in tension whereas strut bending followed by strut buckling are observed in compression. Strain localisation, that occurs during compression tests, depends on nickel weight distribution in the foam. Fracture in tension first takes place at cell nodes and the crack propagates cell by cell. The damaged area in front of a crack is about five cells wide. A detailed description of the three-dimensional morphology is also presented. One third of the cells are dodecahedral and 57 % of the faces are pentagonal. The most frequent cell is composed of two quadrilaterals, two hexagons and eight pentagons. The dimensions of the equivalent ellipsoid of each cell are identified and cell orientation are determined. The geometrical aspect ratio is linked to the mechanical anisotropy of the foam. In tension, a uniaxial analytical model, based on elastoplastic strut bending, is developed. The whole stress-strain curve of the foam is predicted according to its specific weight and its anisotropy. It is found that the non-linear regime of the macroscopic curve of the foam is not only due to the elastoplastic bending of the struts. The model is also extended to two-phase foams and the influence of the hollow struts is analysed. The two-phase foams model is finally applied to oxidized nickel foams and compared with experimental data. The strong increase in the rigidity of nickel foams with an increasing rate of oxidation, is well described by the model. However, a fracture criterion must also be introduced to take into account the oxide layer cracking. A phenomenological compressible continuum plasticity model is also proposed and identified in tension. The identification of the model is carried out using experimental strain maps obtained by a photo-mechanical technique. A validation of the model is provided by investigating the strain field around a hole in a foam. The multiaxial model is extended to a micro-morphic one to incorporate non local features accounting for the size effects observed for small holes. The prediction of the model is evaluated in the case of subsequent fracture of the specimen through crack propagation. (author)

  3. Modelling of the mechanical behaviour and damage of clay-stones: application to the East argillite; Modelisation du comportement mecanique des argiles raides avec prise en compte de l'endommagement: application aux argilites de l'Est

    Energy Technology Data Exchange (ETDEWEB)

    Aublive-Conil, N

    2003-03-15

    The storage in deep geological formation is one of the solutions retained by France for the management of highly long life radioactive waste. The retained host rock is a clay-stone named East argillite located in the departments of Meuse and Haute-Marne. A thermodynamic formulation is used to propose a rheological model, which reproduces the mechanical behavior of clay-stones. Initially, an anisotropic damage plastic model was formulated in order to describe material degradations. Then, the damage plastic model is reformulated in order to taken into account the damage influence on the hydraulic behavior of porous material. The numerical simulations correctly reproduce the mechanical behavior of East Argillites but also the anisotropy of the hydraulic behavior introduced by the damage effect. (author)

  4. Proceedings of the Course on Algorithms and Data Structures for Geometric Computations Held at CISM (Centre International des Sciences Mecaniques) in Udine (Italy) on 8-12 July 1985,

    Science.gov (United States)

    1985-07-26

    Mantica, 3 33100 Udine Italy GAMBOSI Giorgio, Researcher Istituto di Analisi dei Sistemi ed Informatica - CNR Viale A. Manzoni, 30 00185 Roma Italy...cx-cy-plane. the subspace of the location parameters, admoving the cone with vertex at q along L intervals on a long line clustering along the...columns have a semantic meaning besides technical properties such as clustering , avoiding composite keys, and improving performance: They may be used

  5. Application of the concrete aging model to the case of cracked materials and to the coupling with the mechanical properties; Application du modele de degradation du beton au cas des milieux fissures et au couplage avec la mecanique

    Energy Technology Data Exchange (ETDEWEB)

    Torrenti, J.M.; Adenot, F.; Tognazzi, C. [CEA/Saclay, 91 - Gif-sur-Yvette (France); Tognazzi, C. [Toulouse Univ., 31 (France). LMDC; Danese, S. [Ecole Nationale Superieure des Arts et Industries de Strasbourg, 67 - Strasbourg (France); Poyet, S. [Ecole Nationale Superieure de Cachan, 94 (France)

    1998-07-01

    Predicting the long-term behavior of concrete used in radioactive waste disposal requires the knowledge of the effects of constantly renewed water on its chemistry and its coupling with the mechanical properties. In contact with water, concrete undergoes chemical degradation. This degradation influences the mechanical performance of the material as well as cracks could interfere with the chemical degradation. This paper shows how these problems can be treated using the Ca{sup ++} concentration in pore solution as the state variable that conducts the evolution of chemical, physical and mechanical properties. Some comparisons with experimental results are shown. Finally, the problem of the numerical simulation of accelerated tests of cracked samples is discussed. (authors)

  6. Study of the mechanical properties of the electric power station components: the punch test; Etude des proprietes mecaniques des composants de centrales thermiques: l'essai punch test

    Energy Technology Data Exchange (ETDEWEB)

    Isselin, J

    2003-03-15

    The aging of the electric production park implies an increasing need of knowledge concerning the evolution of the mechanical properties of its components. With regard to this problem, the availability in material is more and more small. This work proposes to characterize these properties through a mechanical test called Punch test. The main characteristic of this test is to use very small volume samples. The development of this test has been carried out by the study of a 15 MDV 4-05 steel coming from a steam drum of a thermal power plant after 145000 hours of service. At first, we have measured the influence of the parameters of this test. Then, the study has dealt more particularly on the transition temperature of the material. With the finite element simulation method, the strain hardening coefficient of the material has been determined. (O.M.)

  7. Embrittlement and anodic process in stress corrosion cracking: study of the influent micro-mechanical parameters; Fragilisation et processus anodiques en corrosion sous contrainte: etude des parametres micro-mecaniques influents

    Energy Technology Data Exchange (ETDEWEB)

    Tinnes, J.Ph

    2006-11-15

    We study the influence of local mechanical parameters on crack propagation in Stress Corrosion Cracking, at the scale of the microstructure. Two systems are compared: the CuAl{sub 9}Ni{sub 3}Fe{sub 2} copper-aluminium alloy in synthetic sea water under cathodic polarization, where the crack propagation mechanism is related to strain-assisted anodic dissolution, and the 316L austenitic stainless steel in MgCl{sub 2} solution, where embrittlement mechanisms related to hydrogen effects prevail. We use micro-notched tensile specimen that allow to study isolated short cracks. These experiments are modelled by means of finite elements calculations, and further characterized by Electron Back scattered Diffraction (EBSD) in the case of the 316L alloy. In terms of the local mechanical parameters that control propagation, fundamental differences are outlined between the two systems. They are discussed from the viewpoint of the available models of Stress Corrosion Cracking. (author)

  8. Numerical modelling of coupled phenomena within molten glass heated by induction and mechanically stirred; Modelisation numerique de phenomenes couples dans des bains de verre brasses mecaniquement et elabores en creuset froid inductif

    Energy Technology Data Exchange (ETDEWEB)

    Jacoutot, L

    2006-11-15

    This study reports on a new vitrification process developed by the French Atomic Energy Commission (CEA, Marcoule). This process is used for the treatment of high activity nuclear waste. It is characterized by the cooling of all the metal walls and by currents directly induced inside the molten glass. In addition, a mechanical stirring device is used to homogenize the molten glass. The goal of this study is to develop numerical tools to understand phenomena which take place within the bath and which involve thermal, hydrodynamic and electromagnetic aspects. The numerical studies are validated using experimental results obtained from pilot vitrification facilities. (author)

  9. Experimental study of mechanical behaviour of a clay-stone: application to nuclear waste disposals; Etude experimentale du comportement mecanique d'argiles raides: application au stockage de dechets radio-actifs

    Energy Technology Data Exchange (ETDEWEB)

    Chiarelli, A.S. [Laboratoire de Materiaux et Sciences des Constructions, UPRES JE 2200, IUP Genie Civil et Infrastructures, 95 - Cergy Pontoise (France); Shao, J.F. [Laboratoire de Mecanique de Lille, URA CNRS 1441, EUDIL, 59 - Villeneuve d' Ascq (France); Ledesert, B. [Laboratoire de Sedimentologie et Geodynamique, FRE 2255, 59 - Villeneuve d' Ascq (France); Hoteit, N. [Agence Nationale pour la Gestion des Dechets Nucleaires (ANDRA), 92 - Chatenay Malabry (France)

    2001-02-01

    A study of mechanical behaviour of deep argillaceous rocks from East of France, the 'argilites de l'Est' as a potential host rock for radioactive waste disposal studied by ANDRA, (french national radioactive waste management agency) is presented. Some uniaxial and triaxial compression tests with unloading-reloading cycles were realised on samples from three different depths. Important plastic strains associated to directional degradation of elastic properties show that the two principles strain mechanisms are plasticity and induced anisotropic damage. At microscopic scale, it is related to sliding of clay sheets and oriented microcracks. The influence of mineralogy is that brittle behaviour is more important with calcite while it decreases with clay. (authors)

  10. Syrthes thermal code and Estet or N3S fluid mechanics codes coupling; Couplage du code de thermique Syrthes et des codes de mecanique des fluides N3S et ou Estet

    Energy Technology Data Exchange (ETDEWEB)

    Peniguel, C [Electricite de France (EDF), 78 - Chatou (France). Direction des Etudes et Recherches; Rupp, I [SIMULOG, 78 - Guyancourt (France)

    1997-06-01

    EDF has developed numerical codes for modeling the conductive, radiative and convective thermal transfers and their couplings in complex industrial configurations: the convection in a fluid is solved by Estet in finite volumes or N3S in finite elements, the conduction is solved by Syrthes and the wall-to-wall thermal radiation is modelled by Syrthes with the help of a radiosity method. Syrthes controls the different heat exchanges which may occur between fluid and solid domains, using an explicit iterative method. An extension of Syrthes has been developed in order to allow the consideration of configurations where several fluid codes operate simultaneously, using ``message passing`` tools such as PVM (Parallel Virtual Machine) and the Calcium code coupler developed at EDF. Application examples are given

  11. Coupling of the SYRTHES thermal code with the ESTET or N3S fluid mechanics codes; Couplage du code de thermique SYRTHES et des codes de mecanique des fluides ESTET ou N3S

    Energy Technology Data Exchange (ETDEWEB)

    Peniguel, C [Electricite de France (EDF), 78 - Chatou (France). Direction des Etudes et Recherches; Rupp, I [Simulog, 78 (France)

    1998-12-31

    Thermal aspects take place in several industrial applications in which Electricite de France (EdF) is concerned. In most cases, several physical phenomena like conduction, radiation and convection are involved in thermal transfers. The aim of this paper is to present a numerical tool adapted to industrial configurations and which uses the coupling between fluid convection (resolved with ESTET in finite-volumes or with N3S in finite-elements) and radiant heat transfers between walls (resolved with SYRTHES using a radiosity method). SYRTHES manages the different thermal exchanges that can occur between fluid and solid domains thanks to an explicit iterative method. An extension of SYRTHES has been developed which allows to take into account simultaneously several fluid codes using `message passing` computer tools like Parallel Virtual Machine (PVM) and the code coupling software CALCIUM developed by the Direction of Studies and Researches (DER) of EdF. Various examples illustrate the interest of such a numerical tool. (J.S.) 12 refs.

  12. Deformation and damage modes of deep argillaceous rocks under hydro-mechanical stresses; Modes de deformation et d'endommagement de roches argileuses profondes sous sollicitations hydro-mecaniques

    Energy Technology Data Exchange (ETDEWEB)

    Vales, F.

    2008-12-15

    An experimental identification of the hydro-mechanical behaviour of an argillite rock is proposed within a multi-scale approach. In particular, interest is focused on the spatial and temporal localization of strain and damage in a specimen during hydro-mechanical loading. Firstly, we describe the techniques used to follow the rock evolutions under loading, and in particular Digital Images Correlation (DIC), Acoustic Emission, microscopy and mercury intrusion porosimetry. Measurement errors and device limitations are discussed. The studied material is the Callovo-Oxfordian indurated argillaceous rock (or argillite) of the Bure site where ANDRA has built an underground research laboratory to study the radioactive waste storage. Petrophysical characterizations and microstructural observations by optical and scanning electron microscopy provide an identification of the constitutive phase and a characterization of their spatial distribution and typical sizes. Argillite can be described as a composite structure with a continuous clay matrix and embedded mineral particles, essentially quartz and carbonates. The typical size of these particles ranges from a few micrometers to a few hundreds micrometers, with an average close to 50 {mu}.m. The general experimental procedure combines two steps: in a fist time, imposed suctions bring samples to a given degree of water saturation, and, in a second time, uniaxial mechanical compression tests are performed. To understand the evolutions of the material under hydric and mechanical loading, samples are instrumented with standard measurement techniques, but also with Digital Image Correlation, at both the global scale of the sample and the local scale of the composite microstructure, and with Acoustic Emissions recording. Moisture transfers are imposed by controlled suctions on the range of 150 to 2.8 MPa, corresponding to the relative humidity range of 32 to 98%RH. During pure hydric solicitation, the changes in physical parameters (weight, longitudinal and transverse strains) are continuously recorded until stabilization. When sample equilibrium is reached, uniaxial compressive tests are performed. Samples brought to lower relative humidity undergo an anisotropic shrinkage associated with a water content decrease. Samples in equilibrium at 98%RH swell and store water. Depending of the clay ratio, a significant contribution to this swelling can be shown to be due to the opening of these preexisting cracks and to the creation of new cracks. The macroscopic mechanical response and in particular its linearity and the spatial homogeneity of the strain distribution, depend on the initial rock microstructure (clay ratio) and on the microstructure induced by the suction (new crack network). When suction increases from 2.8 to 150 MPa, Young modulus and strength increase with a factor respectively close to 2 and 3. For dry states, macroscopic strain fields are homogeneous while at the microstructure scale, strain are heterogeneous and clearly correlated with the local distribution of mineral constituents; clayey areas are more deformable than other mineral phase. For wet states, overall and local strain fields are heterogeneous. Strain are affected by the presence of the cracks: close to them, local strain are important but at a distance from cracks large than a few hundreds micrometers, strain distributions are similar to those in the dry states. The main behaviour difference between dry and wet states seems to be due more to the presence of cracks induced by the suctions, than to an intrinsic evolution of the mechanical properties of the clay matrix. The multi-scale quantification of strain heterogeneity by Digital Image Correlation, and the determination of the damage appearance by Acoustic Emission, are useful input data for the development and validation of multi-scale constitutive models for argillite. (author)

  13. A contribution to the study of mechanical behaviour of concrete structures taking into account the effects of desiccation; Contribution a l'etude du comportement mecanique des ouvrages en beton avec prise en compte des effets de la dessiccation

    Energy Technology Data Exchange (ETDEWEB)

    Hubert, F.X

    2004-12-15

    In this work, is given a model of the drying influence on the mechanical behaviour of concrete and a reliable anticipating tool is proposed for engineers. The drying of hardened concrete has several consequences on the mechanical properties of concrete. The desiccation shrinkage is the first sign, generating crack visible at the surface level under the form of crackling and core cracking particularly on the account of the presence of aggregates which prevent the shrinkage of the cement paste to make easily. Then, the elastic parameters are strongly affected (decrease of stiffness, of the Poisson coefficient). A simplified model of the stiffness loss during the drying is proposed under the form of an isotropic hydric damage. The model is validated in the unidimensional case with tests results carried out in the LML. With this model, it is possible to estimate with more accuracy the state of the hydric constraints in concrete. Numerical simulations on 3D structures are then proposed. An application to the case of a wall being manufactured is given. The contributions of the model are tested too in the case where the global mechanical response of cylindrical mortar specimens submitted to drying and to compression tests is simulated. The effect of the capillary suction as well as the increase of the elastic limit during drying are then discussed. At last, the contributions of the model for creep calculations and desiccation are presented. (O.M.)

  14. Coupled effects of the precipitation of secondary species on the mechanical behaviour and chemical degradation of concretes; Les effets couples de la precipitation d'especes secondaires sur le comportement mecanique et la degradation chimique des betons

    Energy Technology Data Exchange (ETDEWEB)

    Planel, D

    2002-06-01

    Sulfate attack of cement-based materials remains an important problem for the durability assessment of containers and disposal engineering barriers dedicated to the long-term storage of radioactive wastes since underground water which may reach these elements contains small quantities of sulfates (7-31 mmol/1). This work contributes to the study of sulfate-induced damage mechanisms, to their understanding and modelling. The experimental phases of this study aimed at the understanding of the different physico-chemical phenomena involved during an external sulfate attack at following their evolution and their impact on the transport and mechanical properties of the material. Leaching experiments in pure water and in a solution of sodium sulfate (with a sulfate content of 15 mmol/1), have been performed simultaneously on OPC paste (w/c 0,4)in order to allow a comparison of test results. The frequent analysis of the leachant has shown a consumption of sulfate ions by the matrix, proportional to the square rate of time. The use of X-Ray Diffraction on powders, obtained by scraping the calcium-depleted part of the samples, led a precise view of the cement paste mineralogy, during sulfate attack. The use of Scanning Electron Microscopy (SEM) and Energy Dispersive Spectrometer (EDS) confirmed the correctness of XRD profiles and brought important informations concerning cracking distribution and localisation. In addition, a visual monitoring of crack appearance and evolution completed the previous observations. Based on these experimental results, a simplified model accounting for the chemical degradation of cement paste in sulfated water has been proposed. A geochemical code, coupling the chemistry in solution with the reactive transport in porous media has been used for this purpose. The model accounts for the evolution of transport properties (diffusivity) associated with the calcium-depleting of the cement matrix and the precipitation of secondary phases (gypsum, ettringite) in the porous space. The results of the reactive transport calculations have then been used to model the mechanical behaviour of the samples subjected to a sulfate attack. The constitutive mechanical model used in this study, is based on physical concepts like the generation of internal auto-stresses in concrete, induced by the precipitation of secondary phases in the porous space. It accounts for anisotropic damage and assumes that cracking can appear depending on several thresholds associated with the behaviour of the material in tension, compression and related to internal stresses originating from secondary phases precipitation. (author)

  15. Mechanical disequilibria in two-phase flow models: approaches by relaxation and by a reduced model; Modelisation des desequilibres mecaniques dans les ecoulements diphasiques: approches par relaxation et par modele reduit

    Energy Technology Data Exchange (ETDEWEB)

    Labois, M

    2008-10-15

    This thesis deals with hyperbolic models for the simulation of compressible two-phase flows, to find alternatives to the classical bi-fluid model. We first establish a hierarchy of two-phase flow models, obtained according to equilibrium hypothesis between the physical variables of each phase. The use of Chapman-Enskog expansions enables us to link the different existing models to each other. Moreover, models that take into account small physical unbalances are obtained by means of expansion to the order one. The second part of this thesis focuses on the simulation of flows featuring velocity unbalances and pressure balances, in two different ways. First, a two-velocity two-pressure model is used, where non-instantaneous velocity and pressure relaxations are applied so that a balancing of these variables is obtained. A new one-velocity one-pressure dissipative model is then proposed, where the arising of second-order terms enables us to take into account unbalances between the phase velocities. We develop a numerical method based on a fractional step approach for this model. (author)

  16. Unique effect of mechanical crushing on the electrochemical intercalation of lithium in carbons of different morphologies; Effet unique du broyage mecanique sur l`intercalation electrochimique du lithium dans des carbones de morphologies differentes

    Energy Technology Data Exchange (ETDEWEB)

    Salver-Disma, F; Tarascon, J M [Universite de Picardie, 80 - Amiens (France)

    1997-12-31

    Lithium ion batteries use an oxide as a positive electrode and a carbon material as a negative electrode. The performances of carbon electrodes have rapidly evolved during the last years thanks to the substitution of soft carbons of Conoco or MCMB-2510 type by graphites (F-399, MCMB-2528) and then by hard carbons. These high capacity carbons (700 mAh/g) have higher service life and volume capacity than graphites but their irreversible losses are greater (>20%). In this work, materials with similar electrochemical performances are prepared by mechanical crushing. Mechanical crushing allows to obtain a wide range of carbon materials with various morphologies, specific surfaces and levels of disorder. The formation of the passivation film is directly linked with the surface of materials. A reaction scheme of the reversible and irreversible capacities has been defined and has permitted to obtain compounds with reversible capacities of 720 mAh/g (2 lithium for 6 carbon). (J.S.)

  17. Modelling the mechanical behaviour of heterogeneous Ta/TA6V welded joints: behaviour and failure criteria; Modelisation du comportement mecanique des liaisons soudees heterogenes Ta/TA6V: comportement et critere de rupture

    Energy Technology Data Exchange (ETDEWEB)

    Paris, Th

    2008-12-15

    As laser welding of two different materials (heterogeneous welding) leads to a joint having a characteristic size close to the millimetre, i.e. much smaller than that of a structure, and as such a junction displays completely different mechanical properties because of the metallurgical transformations induced by intense thermal loading, the aim of this research thesis is to develop a behaviour model, flexible and robust enough, to represent all together the mechanical behaviours of the Ta, the TA6V and the melted zone. This model must be able to take plasticity and visco-plasticity into account, and also to provide a failure criterion through damage mechanics and its coupling with the behaviour. The author first reports the experimental characterization of the base materials (Ta and TA6V) by using tensile tests under different strain rates and different directions, relaxation tests and fatigue shear tests. He also characterizes the melted zone by describing the influence of a thermal treatment (induced by welding) on the formation of the melted zone, and by using different tests: four point bending on notched specimens, nano-indentation test, and longitudinal tensile test. In a second part, the author develops the model within the framework of continuum thermodynamics, and explores the numerical issues. The last part deals with the validation of the model for the concerned materials (Ta and TA6V) and melted zone.

  18. Analyze of phase's mechanical behaviour of a multiphase polycrystalline alloy by X-ray and neutron diffraction; Analyse du comportement mecanique des constituants d'un alliage polycristallin multiphase par diffraction des rayons X et neutronique

    Energy Technology Data Exchange (ETDEWEB)

    Dakhlaoui, R

    2006-12-15

    The aim of this work is to propose a methodology using diffraction methods and theoretical approaches of self-consistent modeling in order to analyze and better understand the mechanical behavior of each phase of hot-rolled duplex stainless steel. The purpose of the experimental study is to characterize the local mechanical behavior of phases under uniaxial loading. X-ray and neutron diffraction which enable to measure strains in each phase separately were used in this aim. Austenitic and ferritic phase stresses are determined by X-ray diffraction during tensile tests. Evolution of the elastic strains in each phase was measured by neutron diffraction using 'time-of-flight' method during tensile and compression tests. Elastic constants were given using the self-consistent model for a purely elastic deformation. To reproduce the mechanical behaviour of the studied material, self-consistent polycrystalline micro-mechanical model for elastoplastic deformation has been adapted and confronted to experimental results. Crystallographic texture and initial residual stresses were considered in this analysis. Critical shear stresses and hardening parameters of each phase of the studied duplex steel have been identified. Results of this study showed that the austenitic phase represents the softest and the most hardenable phase. Taking into account in calculations the initial residual stresses in the non deformed sample leads to the conclusion that the initial stresses modify considerably the values of phase's yield stresses. Good agreement has been noted comparing results obtained by XRD to those obtained by neutron diffraction. The problem of relaxation of normal stresses in the analysed layer by X-rays was analysed and discussed. Using XRD and self-consistent modelling, the effect of the chemical composition of the duplex stainless steel and the influence of ageing at 400 C degrees for 1000 h on the mechanical behaviour of austenitic and ferritic phases have been established. (author)

  19. Coupling of the SYRTHES thermal code with the ESTET or N3S fluid mechanics codes; Couplage du code de thermique SYRTHES et des codes de mecanique des fluides ESTET ou N3S

    Energy Technology Data Exchange (ETDEWEB)

    Peniguel, C. [Electricite de France (EDF), 78 - Chatou (France). Direction des Etudes et Recherches; Rupp, I. [Simulog, 78 (France)

    1997-12-31

    Thermal aspects take place in several industrial applications in which Electricite de France (EdF) is concerned. In most cases, several physical phenomena like conduction, radiation and convection are involved in thermal transfers. The aim of this paper is to present a numerical tool adapted to industrial configurations and which uses the coupling between fluid convection (resolved with ESTET in finite-volumes or with N3S in finite-elements) and radiant heat transfers between walls (resolved with SYRTHES using a radiosity method). SYRTHES manages the different thermal exchanges that can occur between fluid and solid domains thanks to an explicit iterative method. An extension of SYRTHES has been developed which allows to take into account simultaneously several fluid codes using `message passing` computer tools like Parallel Virtual Machine (PVM) and the code coupling software CALCIUM developed by the Direction of Studies and Researches (DER) of EdF. Various examples illustrate the interest of such a numerical tool. (J.S.) 12 refs.

  20. Cationic hetero diffusion and mechanical properties of yttria-stabilized zirconia: influence of irradiation; Heterodiffusion cationique et proprietes mecaniques de la zircone stabilisee a l'oxyde d'yttrium: influence de l'irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Menvie Bekale, V

    2007-12-15

    Cubic yttria-stabilized zirconia (YSZ) is a promising material as target for the transmutation of radioactive waste. In this context, the present work is dedicated to the study of the atomic transport and the mechanical properties of this ceramic, as well as the influence of irradiation on these properties. The preliminary step concerns the synthesis of YSZ cubic zirconia ceramic undoped and doped with rare earths to form homogeneous Ce-YSZ or Gd-YSZ solid solutions with the highest density. The diffusion experiments of Ce and Gd in YSZ or Ce-YSZ were performed in air from 900 to 1400 C, and the depth profiles were established by SIMS. The bulk diffusion decreases when the ionic radius of diffusing element increases. The comparison with literature data of activation energies for bulk diffusion suggests that the cationic diffusion occurs via a vacancy mechanism. The diffusion results of Ce in YSZ irradiated with 4 or 20 MeV Au ions show a bulk diffusion slowing-down at 1000 and 1100 C when the radiation damage becomes important (30 dpa). The mechanical properties of YSZ ceramics irradiated with 944 MeV Pb ions and non irradiated samples were studied by Vickers micro indentation and Berkovitch nano indentation techniques. The hardness of the material increases when the average grain size decreases. Furthermore, the hardness and the toughness increase with irradiation fluence owing to the occurrence of compressive residual stresses in the irradiated area. (author)

  1. A posteriori error analysis for hydro-mechanical couplings and implementation in Code-Aster; Analyse d'erreur a posteriori pour les couplages hydro-mecaniques et mise en oeuvre dans Code-Aster

    Energy Technology Data Exchange (ETDEWEB)

    Meunier, S

    2007-11-15

    We analyse approximations by finite elements in space and finite differences in time of coupled Hydro-Mechanical (HM) problems related to the quasi-static linear poro-elasticity theory. The physical bases of this theory are briefly restated and an abstract setting is proposed to perform the mathematical study of the stationary and un-stationary versions of the HM problem. For the stationary version, the well-posedness of the continuous and discrete problems are established and the a priori error analysis is performed. Then, we propose the a posteriori error analysis by using two different techniques suited to estimate the displacement error and the pressure error, respectively, both in the H{sub x}{sup 1}-norm. The classical properties of reliability and optimality are proved for the associated error estimators. Some numerical experiments using Code-Aster illustrate the theoretical results. For the un-stationary version, we first establish a stability result for the continuous problem. Then, we present an optimal a priori error analysis using elliptic projection techniques. Finally, the a posteriori error analysis is performed by using two different approaches: a direct approach and an elliptic reconstruction approach. The first is suited to estimate the pressure error in the L{sub t}{sup 2}(H{sub x}{sup 1})-norm and the second is suited to estimate the displacement error in the L{sub t}{sup {infinity}}(H{sub x}{sup 1})-norm and the pressure error in the L{sub t}{sup {infinity}}(H{sub x}{sup 1})-norm. Numerical experiments using Code-Aster complete the theoretical results. (author)

  2. Influence of phase transformations on the mechanical behaviour of refractory ceramics at high temperature;Effets des transformations de phase sur la tenue mecanique a haute temperature des ceramiques refractaires

    Energy Technology Data Exchange (ETDEWEB)

    Schmitt, N. [LMT-Cachan, ENS de Cachan, UMR 8535 CNRS, Universite Paris 6, 94 - Cachan (France); IUFM de Creteil, Universite Paris-Est Creteil, 93 - Saint-Denis (France); Poirier, J. [CNRS-CEMHTI, 45 - Orleans (France); Polytech, Universite d' Orleans, 45 - Orleans (France)

    2009-07-01

    Refractories used at high temperature are subjected to high chemical and mechanical stresses. The mastery of their microstructure as well as the phase changes occurring in service is essential to ensure resistance to wear and failure of refractory linings. Great progress has been made: combining efficient techniques for the investigation of the microstructure with powerful numerical tools (thermochemical and thermo-mechanical computations) provides information (e.g., degradation mechanisms) that cannot be obtained directly. Also multi-physical and multi-scale models developing materials with high-performance for higher temperature and with longer lifetime. In this paper, through several examples we show some interactions between the mechanical behavior and the microstructure transformations of refractory ceramics. The tools developed to characterize their microstructure change in situ (e.g., at high temperature) and to identify their kinetics are described. Some methodologies and tools developed in recent years, today, provide a better understanding of in-service behavior of refractories while identifying the critical material and process parameters likely to increase life-time. (authors)

  3. Etude theorique et experimentale de la correlation entre la resistance aux chocs thermiques et aux chocs mecaniques des materiaux refractaires utilises dans les fours de traitement de l'aluminium

    Science.gov (United States)

    Sebbani, Mohamed Jamal Eddine

    2001-07-01

    This work is a theoretical and experimental study of the correlation between the resistance to thermal shock and mechanical shock of refractory materials. The study of thermal shock showed that the Bahr and Hasselman approaches are alike and that they can be combined into a single, more general approach. This generalisation allowed the division of the theoretical models into two groups: the Hasselman model and the Harmuth model. However, neither of these approaches can predict the behaviour of all refractory materials submitted to thermal shock. Therefore, the generalisation of the Hasselman approach is more appropriate for more dense materials while the Hartmuth approach is more appropriate for less dense materials. The influence of porosity on the energy of rupture helped to explain the behaviour of the less dense material. The absence of generalisation in this case allows those parameters that could be correlated with thermal shock resistance to be dependent on the type of refractory. The study of mechanical shock provided a better understanding of this mechanism. The work performed showed, theoretically and experimentally, that the resistance of the refractory materials could be correlated with the parameter s20 Egwof n-22 . This new parameter helped to explain the statistical correlation between the resistance to mechanical impact and the soxRst parameter established in earlier work. The sintering influence, which makes the refractories more resistant to this type of demand, notably by reducing the "n" coefficient, was shown. This part of the study allowed the establishment of equivalence between thermal fatigue and fatigue by mechanical impact. An evaluation of the correlation between the two mechanisms demonstrated, theoretically and experimentally, that the mechanical and thermal demands could only be exceptionally correlated. In the case of thermal shock, which are imposed deformation demands, it is the shorter cracks which are the most dangerous. However, in the case of mechanical shock, which is constraint imposed, it is the longer cracks that are the most harmful. (Abstract shortened by UMI.)

  4. Very heavy iron-punching concretes; Betons tres lourds a base de riblons

    Energy Technology Data Exchange (ETDEWEB)

    Dubois, F [Commissariat a l' Energie Atomique, Saclay(France). Centre d' Etudes Nucleaires

    1966-07-01

    The present report deals with all the heavy iron-punching concretes, metallic wastes produced by the transformation industry. After a detailed description of the physical properties of metallic aggregates, a classification of heavy mortars is given, into three main categories: steel-shot grouts d = 5,3 - 6; steel-shot grouts mixed with a mineral d = 3,7 - 4,2; injection heavy grouts d = 3,5 - 4. The following chapter describes iron-punching concretes the most used in the atomic industry: iron-punching concretes mixed with cast-iron - iron-punching concretes mixed with magnetite; iron-punching concretes mixed with barite; iron-punching concretes mixed with limonite; iron-punching concretes mixed with boron. The compositions of these concretes are given together with their physical and mechanical characteristics. Numerous diagrams make it possible to find rapidly the proportions of the constituents of these concretes as a function of the required density. Technical advice and specifications are given in an appendix together with a bibliography of these heavy concretes. (author) [French] Le present rapport traite de l'ensemble des betons lourds realises a l'aide de riblons, dechets metalliques fournis par l'industrie de transformation. Apres une description detaillee des proprietes physiques des agregats metalliques, les mortiers lourds sont d'abord presentes en les classant en trois grandes categories: les mortiers a base de grenailles d 5,3 a 6; les mortiers a base de grenailles avec addition d'un mineral d 3,7 a 4,2; les mortiers lourds injectables d = 3,5 a 4. Le chapitre suivant decrit les betons a base de riblons les plus utilises, dans l'industrie atomique: les betons de riblons avec addition de fonte; les betons de riblons avec addition de magnetite; les betons de riblons avec addition de barytine; les betons de riblons avec addition de limonite; les betons de riblons avec addition de bore. Les compositions de ces betons ainsi que leurs caracteristiques

  5. Special concretes for protection in piles (1963); Les betons speciaux dans la protection des piles (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Condat, M.J.; Lafore, P.; Rastoin, J. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1963-07-01

    la mise en oeuvre, la stabilite dans le temps et la tenue aux rayonnements et a la chaleur. Des annexes et des tableaux donnent des precisions et des valeurs numeriques. L'annexe 1 traite de la question de l'eau dans les betons. L'annexe 2 donne une classification des betons basee principalement aur leur densite. Enfin dix tableaux donnent pour seize betons particulierement representatifs, les compositions ainsi que les valeurs des caracteristiques physiques et mecaniques. (auteurs)

  6. Very heavy iron-punching concretes; Betons tres lourds a base de riblons

    Energy Technology Data Exchange (ETDEWEB)

    Dubois, F. [Commissariat a l' Energie Atomique, Saclay(France). Centre d' Etudes Nucleaires

    1966-07-01

    leurs caracteristiques physiques et mecaniques sont fournies. De nombreux diagrammes permettent d'evaluer rapidement les proportions des constituants de ces betons en fonction de la densite desiree. Des recommandations et des specifications techniques sont donnees en annexe ainsi qu'une bibliographie sur ces betons lourds. (auteur)

  7. Processing and Pre-Treatment of Solid Radioactive Waste; Conditionnement des Dechets Radioactifs Solides; 041e 0411 0420 0414 ; Acondicionamiento de los Desechos Radiactivos Solidos

    Energy Technology Data Exchange (ETDEWEB)

    Cerre, P. [Service de Controle des Radiations et de Genie Radioactif, Commissariat a l' Energie Atomique, Saclay (France)

    1960-07-01

    As solid radioactive waste varies in form, dimensions and volume, the Atomic Energy Commission first of all reduces the volume by breaking up and compressing the waste. Since the temporary storage of such waste is always attended by the risk of contamination, an efficient packing system has been devised and adopted. This consists of embedding the waste in the heart of a specially-designed block of concrete possessing the following characteristics: Great strength Maximum insolubility Resistance to corrosion Maximum imperviousness Protection against radiation. It is thus quite safe to store these blocks with a view to final dumping. (author) [French] Les dechets actifs solides etant de formes, de dimensions et de volumes varies, le C.E.A. procede en premier lieu a une reduction de volume par fractionnement et compactage. L'emmagasinage provisoire de tels dechets ne pouvant se concevoir sans risques de contamination, un procede efficace d'emballage a ete etudie et realise. Il consiste a noyer les dechets dans un beton specialement etudie qui presente les caracteristiques suivantes: - Forte resistance mecanique . - Insolubilite maximum - Resistance a la corrosion - Etancheite maximum - Protection contre le rayonnement Il est alors possible de conserver sans danger les blocs formes en vue d'un rejet definitif ulterieur. (author) [Spanish] Como los desechos radiactivos solidos difieren mucho por su forma, dimension y volumen, el Commissariat efectua en primer lugar una reduccion de volumen desmenuzandolos y comprimiendolos. El almacenamiento provisional de esos desechos presenta siempre riesgos de contaminacion, por lo que se ha estudiado y llevado a la practica un sistema especial de embalaje. Este sistema consiste en empotrar los desechos en un hormigon especialmente estudiado que ofrece las siguientes caracteristicas: - Fuerte resistencia mecanica - Maximum de insolubilidad - Resistencia a la corrosion - Maximum de estanquidad - Proteccion contra las radiaciones De

  8. Special concretes for protection in piles (1963); Les betons speciaux dans la protection des piles (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Condat, M J; Lafore, P; Rastoin, J [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1963-07-01

    stabilite dans le temps et la tenue aux rayonnements et a la chaleur. Des annexes et des tableaux donnent des precisions et des valeurs numeriques. L'annexe 1 traite de la question de l'eau dans les betons. L'annexe 2 donne une classification des betons basee principalement aur leur densite. Enfin dix tableaux donnent pour seize betons particulierement representatifs, les compositions ainsi que les valeurs des caracteristiques physiques et mecaniques. (auteurs)

  9. Testing on air cleaning systems: Testing of the components in-place tests; Controle des installations d'epuration de l'air essais de conformite des elements: Tests in situ

    Energy Technology Data Exchange (ETDEWEB)

    Billard, F; Brion, J [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1967-07-01

    The reliability of air cleaning systems is dependent on testing they are submitted to. Although in-place tests are the most important as they act as final tests upon achieved plants, component tests are necessary too. They allow detection of defective units before they are installed, partition of unit defects from mounting defects and they are more sensitive. For similar reasons, material teats are most useful. The various tests are described, about aerosol filters for one part, iodine trap for the other. The checked features are: materials nature, units sizes, efficiency, air resistance, flammability, humidity resistance, temperature resistance, adsorbent friability, etc... On iodine trapping systems, small check traps, working by-pass with the main trap are periodically subjected to efficiency test. This control allow to cut down the in-place tests frequency, particularly when poisoning from organic vapours is to be feared. (authors) [French] La surete de fonctionnement des installations d'epuratition de l'air esf fonction des controles auxquels ces installations sont soumises. Si les tests in situ sont les plus importants puisqu'ils constituent le controle final de l'installation terminee, les essais de conformite des elements constitutifs sont egalement necessaires. Ils permettent l'elimination d'elements defectueux avant leur mise en place, la discrimination des defauts du montage de ceux de l'element et sont en outre plus sensibles. De meme, le controle des materiaux constitutifs de l'element s'avere fort utile. On decrit les differents controles, d'une part, pour les fittres a aerosols, d'autre part, pour les pieges a iode. Les caracteristiques verifiees sont: nature des materiaux, dimenesions des elements, efficacite, perte de charge, resistance mecanique, inflammabilite, tenue a l'humidite, tenue a la temperature, resistance au detassement des pieges a iode, friabilite du materiau adsorbant, etc... En ce qui concerne les installations de piegeage d

  10. Development and testing of the EDF-2 reactor fuel element; Essais et mise au point de l'element combustible pour le reacteur EDF-2

    Energy Technology Data Exchange (ETDEWEB)

    Delpeyroux, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Furhmann, R [Societe Industrielle de Combustible Nucleaire (France)

    1964-07-01

    rassemble les etudes qui ont ete necessaires pour mener a bien la definition de l'element combustible EdF 2. Apres un bref rappel des caracteristiques du reacteur EdF 2 et des options preliminaires ayant permis de fixer un avant-projet d'element combustible, on aborde les etudes proprement dites: - Etudes uranium: essais de passage d'une couronne interne du tube en phase {beta}, flechage du tube sous l'action d'une force concentree, soudage des pastilles d'extremites et verification de leur etancheite. La tenue du tube a l'ecrasement et la resistance des pastilles a l'enfoncement sous l'action de la pression externe sont etudiees en detail dans un autre rapport CEA - Etudes gaine: rappel des conditions de fabrication et verification de l'etancheite de la gaine, tenue des ailettes au fluage sous l'action du courant gazeux - Etudes d'extremites: fluage en compression et soudage des bouchons a la gaine. - Etudes cartouche: determination des caracteristiques des gorges d'ancrage gaine-combustible et des conditions de gainage, verification de la tenue au cyclage thermique de l'element combustible, determination de la chute de temperature au contact gaine-combustible traitee en detail dans un autre rapport CEA, - Etudes de l'ensemble: les etudes se rapportant a la chemise de graphite, au support et aux vibrations de la cartouche ont ete traitees par le service des Etudes Mecaniques et Thermiques (Section de Mecanique), Dans ce domaine, la Section d'Etude d'Elements Combustibles a etudie la tenue des centreurs sous l'action du courant gazeux. L'aboutissement des etudes est constitue par le dessin de l'element combustible, le schema de fabrication et les normes de fabrication. La validite de l'ensemble de ces essais hors pile sera confirmee par des assais en pile qui sont en cours et par l'irradiation des elements dans le reacteur EdF 2 lui-meme. En conclusion, on donne l'orientation des etudes pour l'amelioration de l'element combustible et la definition d'un element combustible

  11. Fulltext PDF

    Indian Academy of Sciences (India)

    such an effect, because the plane of the moon's orbit turns once in about eighteen ... Dividing by zero is bad. Dividing ... instituted for the best solution 3. Poincare's ... Nouvelles de la Mecanique Celeste' (New methods of Celestial. Mechanics) ...

  12. Structure study and properties of rare earth-rich glassed for the conditioning of nuclear waste; Etude des caracteristiques structurales et des proprietes de verres riches en terres rares destines au confinement des produits de fission et elements a vie longue

    Energy Technology Data Exchange (ETDEWEB)

    Bardez, I

    2004-11-15

    A new nuclear glass composition, able to immobilize highly radioactive liquid wastes from high burn-up UO{sub 2} fuel, was established and its structure studied. The composition of the selected rare earth-rich glass is (molar %): 61.79 SiO{sub 2} - 8.94 B{sub 2}O{sub 3} - 3.05 Al{sub 2}O{sub 3} - 14.41 Na{sub 2}O - 6.32 CaO - 1.89 ZrO{sub 2} - 3.60 RE{sub 2}O{sub 3} (with RE = La, Ce, Pr and Nd) The aim of this study was to determine the local environment of the rare earth in this glass and also to glean information about the effect of glass composition on the rare earth neighbouring (influence of Si, B, Al, Na and Ca contents). To this end, several series of glasses, prepared from the baseline glass, were studied by different characterisation methods such as EXAFS spectroscopy at the neodymium L{sub III}-edge, optical absorption spectroscopy, Raman spectroscopy and {sup 29}Si, {sup 27}Al and {sup 11}B MAS-NMR. By coupling all the results obtained, several hypotheses about the nature of the rare earth neighbouring in the glass were proposed. (author)

  13. Studies on the translocation pattern, persistence characteristics and metabolic pathway of sumithion [O, O-dimethyl-O-(3-methyl-4-nitrophenyl) phosphorothioate] in the cocoa tree Theobroma Cacao L; Etudes sur la repartition par translocation, les caracteristiques de persistance et les processus metabolitiques du sumithion [O, O-dimethyl-O-(3-methyl-4-nitrophenyl) phosphorothionate] dans le cacaoyer Theobroma Cacao L

    Energy Technology Data Exchange (ETDEWEB)

    Sundaram, Alamelu; Sundaram, K. M.S. [Department of Chemistry, University of Ghana, Legon (Ghana)

    1970-01-15

    The translocation pattern and metabolic pathway of the contact insecticide sumithion in cocoa trees, following a foliar application, was examined using {sup 32}P-labelled and non-radioactive sumithion. The translocation pattern revealed that initially the radioactivities of bark samples were the highest while those of pod samples (cocoa beans in particular) were the smallest; but in the course of ca. 2,5 months, the radioactivities of bark samples decreased rapidly while those of cocoa beans increased steadily. This shows that {sup 32}P from the insecticide was eventually incorporated into the proteins which tended to be accumulated in the cocoa beans. The chloroform/water partition technique, employed to separate the anticholinesterase agents (sumithion and its oxidation product, sumioxon) from the hydrolysed and/or metabolized product(s), divulged the absence of any measurable radioactivities in the chloroform extract of the bark and xylem samples after a period of 15 days from the date of application, thus indicating that the absorbed sumithion (and also sumioxon) underwent complete degradation within that period. Furthermore, the radioactivities of the water layer decreased with time (within one month) while those of the residue increased, hence indicating that the water- soluble {sup 32}P-materials were converted into water-insoluble materials which were incorporated in the residue. Spectrophotometric and column-chromatographic methods, adopted to detect and to estimate the amounts of anticholinesterase agents in the leaves of the sumithion-treated cocoa seedlings at various intervals after treatment, revealed that sumithion absorbed by the plant (only in very small quantities, 9 ± 3 ppm) underwent complete oxidation within a period of five days after application, because no sumithion was detectable in the plant after this period. Also sumioxon, which was detectable in the plant (in quantities of 15 ± 4 ppm) only after this 5-day period, seemed to have undergone complete degradation within an interval of 10 days after treatment, i. e. within an interval of 5 days after the day from which it was detectable. Thus the presence of anticholinesterase agents in the cocoa plants was shown to be practically nil after a period of 10 days from the date of application. In the present investigation it became evident from the uptake studies that {sup 32}P-materials were detectable in the tree even up to 72 days after the insecticide was applied; the chloroform/water partition technique showed the presence of {sup 32}P-materials in the water layer and in the residue up to 28 days after treatment whereas the spectrophotometric and column-chromatographic techniques were able to detect sumithion and sumioxon only up to 10 days after application. This definitely indicated that during this 10-day period sumithion and sumioxon underwent complete degradation and were hydrolysed into water-soluble phosphoric and substituted phosphoric acid-{sup 32}P which were probably utilised later in the formation of water-insoluble proteins- {sup 32}P of high molecular weights. These proteins- {sup 32}P seem to persist for a considerable length of time in the tree thus accounting for the persistent radioactivity even up to ca. 3 months after application. (author) [French] Les auteurs ont étudié la répartition par translocation et les processus métabolitiques du sumithion, insecticide par contact, dans le cacaoyer, après application foliaire de ce produit, soit ordinaire, soit marqué avec {sup 32}P. La répartition par translocation montre que la radioactivité est initialement le plus élevée dans les échantillons d’écorce et le plus faible dans les échantillons de fruits (fèves de cacao en particulier). Ensuite, pendant environ deux mois et demi, la radioactivité de l'écorce décroît rapidement alors que celle des fèves augmente constamment, ce qui prouve que {sup 32}P de l'insecticide finit par être incorporé dans les protéines qui tendent à s'accumuler dans les fèves de cacao. En séparant les agents anticholinestérasiques (sumithion et son dérivé, le sumioxon) des produits hydrolisés ou métabolisés, par partage chloroforme/eau, on met en évidence 1’ absence de toute radioactivité décelable dans l'extrait chloroformique d'échantillons d'écorce-et de xylème, quinze jours après l'application du radioisotope; on voit ainsi que le sumithion absorbé (de même que le sumioxon) sont complètement dégradés au cours de cette période. En outre, la radioactivité de la couche aqueuse décroît avec le temps (pendant un mois), alors que la radioactivité du résidu augmente, ce qui montre que les substances hydrosolubles contenant {sup 32}P se sont transformées en matières insolubles, incorporées aux résidus. L’ analyse qualitative et quantitative, par spectrophotométrie et Chromatographie sur colonne, des agents anticholinestérasiques dans les feuilles de jeunes, cacaoyers traités au sumithion, â différents intervalles de temps après le traitement, montre que le sumithion absorbé par la plante (en très faible quantité uniquement, 9± 3 ppm) est complètement oxydé au cours des cinq jours suivant l’application, car il n'est plus décelable dans la plante après cette période. Le sumioxon, qui devient décelable dans la plante (en quantités de 15 ± 4 ppm) seulement après cette période de cinq jours, semble être complètement dégradé dans les dix jours suivant le traitement, c’est-à-dire au cours d’une période de cinq jours après le moment où il devient décelable. On peut en conclure que la présence d’agents anticholinestérasiques dans les cacaoyers devient pratiquement nulle dix jours après le traitement. Au cours des recherches, les études sur la translocation ont montré à V évidence que les produits marqués avec {sup 32}P restent décelables dans l'arbre jusqu' à 72 jours après le traitement par l'insecticide. Le partage chloroforme/eau révèle la présence de substances marquées avec {sup 32}P dans la couche aqueuse et dans le résidu jusqu' à 28 jours après le traitement, alors que la spectrophotométrie et la Chromatographie sur colonne ne décèlent le sumithion et le sumioxon que jusqu' à 10 jours après l'application. Il est donc évident qu' au cours de cette période de 10 jours le sumithion et le sumioxon sont complètement dégradés et hydrolisés en acide phosphorique et en acide phosphorique ({sup 32}P) solubles dans l' eau, probablement utilisés ultérieurement pour la formation des protéines ({sup 32}P) de haut poids moléculaire, insolubles dans l'eau. Ces protéines ({sup 32}P) semblent persister dans l' arbre pendant un temps remarquablement long, pouvant ainsi expliquer la présence d' une radioactivité jusqu’ à environ trois mois après le traitement. (author)

  14. Tracking techniques for the characteristics method applied to the resolution of the neutrons transport equation in multi scale domains; Techniques de tracage pour la methode des caracteristiques appliquee a la resolution de l'equation du transport des neutrons en domaines multi-dimensionnels

    Energy Technology Data Exchange (ETDEWEB)

    Fevotte, F. [CEA Saclay, Dept. Modelisation de Systemes et Structures (DEN/DANS/DM2S/SERMA), 91 - Gif sur Yvette (France)

    2008-07-01

    At the various stages of a nuclear reactor's life, numerous studies are needed to guaranty the safety and efficiency of the design, analyse the fuel cycle, prepare the dismantlement, and so on. Due to the extreme difficulty to take extensive and accurate measurements in the reactor core, most of these studies are numerical simulations. The complete numerical simulation of a nuclear reactor involves many types of physics: neutronics, thermal hydraulics, materials, control engineering, Among these, the neutron transport simulation is one of the fundamental steps, since it allows computation - among other things - of various fundamental values such as the power density (used in thermal hydraulics computations) or fuel burn-up. The neutron transport simulation is based on the Boltzmann equation, which models the neutron population inside the reactor core. Among the various methods allowing its numerical solution, much interest has been devoted in the past few years to the Method of Characteristics in unstructured meshes (MOC), since it offers a good accuracy and operates in complicated geometries. The aim of this work is to propose improvements of the calculation scheme bound on the two dimensions MOC, in order to decrease the needed resources number. (A.L.B.)

  15. Study of the carbonaceous fraction of the atmospheric aerosol in Chamonix and St Jean de Maurienne: seasonal evolutions, source and chemical characteristics; Etude de la fraction carbonee de l'aerosol atmospherique a Chamonix et St Jean de Maurienne: evolutions saisonnieres, sources et caracteristiques chimiques

    Energy Technology Data Exchange (ETDEWEB)

    Aymoz, G

    2005-03-15

    The atmospheric aerosols play an important role in the earth climatic system. They are also at the origin of air pollution problems in urban areas. However, their influence on the global climactic change, as well as their chemical properties in urban zone, is still very poorly known. One of the main reasons to that is the lack of information on one of the major components of aerosol, the carbonaceous matter. This work focuses on a better knowledge of this particulate carbonaceous matter. This study presents measurements of carbonaceous matter (OC and EC) in aerosol (PM10) performed within the framework of the program POVA, between February 2001 and June 2003 in Chamonix and St Jean de Maurienne (French Alps). This series represents one of the first of this type for basic sites of alpine valleys, characterized by emissions located in the bottom of the valleys and strong temperature inversions in winter, limiting the dispersion of pollutants. The POVA program, centred on the study of air pollution in these valleys, was proposed following the closing of the 'Tunnel du Mont Blanc', in 1999. One of the main objectives was to evaluate the sources of pollution by particles, in particular the share due to the international heavy duty traffic. We could establish that, on the two sites and while the international heavy duty traffic was not restored in the Chamonix Valley, this source represented approximately a third of the observed mass of particles, and was at the origin of a weaker fraction of the carbonaceous matter mass. The extremely primary character of the carbonaceous matter is a remarkable specificity of our sites. The source of carbonaceous matter represented by light vehicles emissions could not be studied. Then, it appears that combustion of biomass (probably from fireplaces) plays an important role, increased in the case of low temperatures, on the levels of pollution by particles. Lastly, the potential impact of the semi-volatile matter condensation at the low temperatures remains an assumption to be tested. On a more general point of view, several results can be pointed out concerning the organic matter: 1. The conversion factor of organic carbon mass to organic matter mass is undoubtedly very variable for a given site (in particular, its variability is probably largely higher than 0,2). 2. The generally allowed assumptions for the calculation of the secondary fraction of OC appeared false in the case of our study, and the method seems in the general case very dubious. 3. The soluble fraction of OC is very important on our sites. The primary source of biomass combustions is an important primary source of WSOC. This result is in disagreement with the general assumption that WSOC is mostly with a secondary origin. (author)

  16. Characteristics of the Beam-Plasma Discharge; Caracteristiques de la 'Decharge Faisceau-Plasma'; ХАРАКТЕРИСТИКИ РАЗРЯДА ПУЧКА В ПЛАЗМЕ; Caracteristicas de la Descarga Haz-Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Smullin, L. D.; Getty, W. D. [Massachusetts Institute of Technology, Cambridge, MA (United States)

    1966-04-15

    In this paper we summarize recent work done at M.I.T. on the study of the electron-beam/plasma interaction. When an electron beam passes through a plasma, it excites oscillations at the plasma frequency. These microwave oscillations sustain a microwave discharge, and we have named the entire process the ''beam-plasma discharge''. Ionization of the ambient gas is carried on by energetic plasma electrons that have been accelerated by the oscillatory fields. The result is the production of a hot-electron plasma inside the magnetic mirror. Since the parameters of the beam plasma discharge appear to be unfavorable for direct ion heating by a beam-plasma interaction, we have begun experiments in which additional RF energy is applied in order to excite ion cyclotron oscillations for ion heating. Results to be discussed are plasma stability, density, average energy, and peak energy of the plasma electrons; and preliminary results on ion heating. Experiments are carried out with pulsed 10 to 15-kV, 10 to 15-A electron beams injected along the axis of a magnetic mirror into a drift region containing H2 at 10{sup -5} to 10{sup -4} Torr. The electron density of the 1-liter plasma is typically 10{sup 12} to 10{sup 13} cm{sup -3}, and the transverse energy density is typically 10{sup 15} eV cm{sup -3}, corresponding to transverse electron ''temperatures'' of 10{sup 2} to 10{sup 3} eV. Measured X-ray energies indicate the existence of electrons with energies of 50 to 100 keV. The decay of the plasma after beam turn-off is in two stages: a relatively rapid loss of low-energy electrons, {tau}{<=} 1000 {mu}sec, and a slow decay of high-energy electrons with {tau}= 10 to 50 msec. A second experiment is carried out with the same electron beam parameters, magnetic field configuration and pressure range. The plasma dimensions are twice as large. Remarkably different plasma energy parameters are obtained by introducing gas with a fast, pulsed gas valve, thereby establishing a pressure gradient. Gas pumping by the plasma is greatly reduced at the same plasma density and energy. Average and peak electron energies are increased tenfold over their values with uniform gas density. Occasionally an instability ''break'' is observed in the afterglow that corresponds to a loss of the low-energy plasma. (author) [French] Les auteurs donnent un apercu des travaux recemment effectues a l'Institut de technologie du Massachusetts en vue d'etudier l'interaction d'un faisceau d'electrons et d'un plasma. Lorsqu' un faisceau d'electrons traverse un plasma, il excite des oscillations a la frequence du plasma. Comme ces oscillations a micro-ondes entretiennent une decharge a microondes, les auteurs ont appele l'ensemble du processus 'decharge faisceau-plasma'. Le gaz ambiant est ionise par les electrons de haute energie du plasma, prealablement acceleres par les champs oscillants. Il en resulte la formation d'un plasma d'electrons chauds a l'interieur de la machine a miroirs. Etant donne que les parametres de la 'decharge faisceau-plasma' ne semblent pas favoriser le chauffage direct des ions par une interaction du faisceau et du plasma, les auteurs ont entrepris des experiences au cours desquelles ils appliquent une energie H.F. supplementaire en vue de provoquer des oscillations cyclotroniques des ions pour le chauffage de ceux-ci. La discussion porte sur la stabilite du plasma, la densite, l'energie moyenne et l'energie maximum des electrons du plasma ainsi que sur les resultats preliminaires relatifs au chauffage des ions. Des experiences sont en cours a l'aide de faisceaux d'electrons puises de 10 a 15 keV et de 10 a 15 A, injectes le long de l'axe d'un miroir magnetique dans la region de derive contenant H{sub 2} a une pression de 10{sup -5} a 10{sup -4} Torr. La densite des electrons d'un plasma de 1 l est normalement de 10{sup 12} a 10{sup 13} cm{sup -3} et la densite d'energie transversale de 10{sup 15} eV cm{sup -3}, ce qui correspond a une energie electronique transversale de 10{sup 2} a 10{sup 3} eV. Les energies des rayons X mesurees permettent de conclure a l'existence d'electrons d'une energie de 50 a 100 keV. La decroissance du plasma apres la coupure du faisceau s'opere en deux etapes: perte relativement rapide en electrons de faible energie, {tau} Less-Than-Or-Equal-To 1000 {mu}s, et decroissance lente des electrons de haute energie, {tau} = 10 a 50 ms. Les auteurs font une deuxieme experience en utilisant les memes valeurs des parametres du faisceau d'electrons et la meme configuration du champ magnetique, dans le meme intervalle de pressions; les dimensions du plasma sont doubles. Ils obtiennent, pour l'energie du plasma, des parametres qui presentent des differences remarquables en introduisant un gaz par une vanne a gaz puise et en creant ainsi un gradient de pressions. Le pompage du gaz par le plasma est sensiblement diminue, la densite et l'energie du plasma etant les memes. Les energies maximum et moyenne des electrons sont decuples par rapport aux valeurs qu'elles atteignent lorsque la densite du gaz est uniforme. On observe parfois une rupture d'instabilite dans le trainage, qui correspond a une perte du plasma a basse energie. (author) [Spanish] En esta memoria se resumen los trabajos reciente- ' mente realizados en el 041C 041B . 0422 . con miras a estudiar la interaccion de un haz electronico con un plasma. Cuando un haz de electrones atraviesa un plasma, excita oscilaciones a la frecuencia del plasma. Estas oscilaciones de micro-ondas mantienen una descarga de micro-ondas; los autores han denominado el proceso completo 'descarga haz-plasma'. La ionizacion del gas ambiental es realizada por los electrones plasmaticos . de alta energia, previamente acelerados por los campos oscilatorios. El resultado es la formacion de un plasma de electrones calientes dentro del espejo magnetico. Puesto que los parametros de la descarga haz-plasma no parecen favorecer el calentamiento directo de los iones por una interaccion haz-plasma, los autores han emprendido experimentos en los cuales se aplica energia de radiofrecuencia suplementaria con objeto de provocar oscilaciones ionico-ciclotronicas para el calentamiento de los iones. La discusion se refiere a la estabilidad del plasma, a la densidad, energia media y maxima de los electrones del plasma y a resultados preliminares sobre el calentamiento de los iones. Se estan realizando experimentos con haces electronicos pulsados, de 10 a 15 keV y de 10 a 15 A, que se inyectan a lo largo del eje de un espejo magnetico, en una region de deriva que contiene H{sub 2} a una presion de 10{sup -5}-10{sup -4} Torr. El valor tipico de la densidad electronica en un plasma de 11 es 10{sup 12}-10{sup 13} cm{sup -3} y la densidad de energia transversal asciende a 10{sup 15} eV cm{sup -3}, lo que corresponde a 'temperaturas' electronicas transversales de 10{sup 2} a 10{sup 3} eV. Las energias medidas de los rayos X indican la existencia de electrones con energias de 50 a 100 keV. Despues de interrumpir el haz, el plasma decrece en dos fases: una perdida relativamente rapida de electrones de pequena energia, {tau} Less-Than-Or-Equal-To 1000 {mu}s, y decrecimiento lento de electrones de gran energia, {tau}= 10 a 50 ms. Se describe otro experimento ejecutado con iguales parametros de haz electronico, configuracion de campo magnetico y gama de presiones. Las dimensiones del plasma son dobles que en el caso anterior. Inyectando gas a traves de una valvula rapida pulsada, para crear un gradiente de presion, se obtienen parametros de la energia del plasma sensiblemente diferentes. El bombeo del gas por el plasma se reduce en forma considerable a la misma densidad y energia plasmaticas. Las energias electronicas medias y maximas son diez veces mayores que las observadas cuando la densidad del gas es uniforme. A veces se registra una inestabilidad 'disruptiva' en la luminiscencia residual, que corresponde a una perdida de plasma de baja energia. (author) [Russian] V dannoj annotacii my podvodim itog nedavnej raboty po izucheniju vzaimodejstvija jelektronnogo puchka s plazmoj, prodelannoj v Massachuzetskom tehnologicheskom institute. Kogda jelektronnyj puchok prohodit cherez plazmu, on vozbuzhdaet kolebanija na plazmennoj chastote. Jeti mikrovolnovye kolebanija podderzhivajut mikrovolnovyj razrjad, i my nazvali ves' process ''puchkovym razrjadom'. Ionizacija okruzhajushhego gaza osushhestvljaetsja jelektronami vysokoj jEhnergii iz plazmy, kotorye uskorjajutsja poljami kolebanij. Rezul'tatom javljaetsja obrazovanie gorjachej jelektronnoj plazmy vnutri ustanovki s magnitnymi probkami. Poskol'ku parametry razrjada puchka v plazme predstavljajutsja neblagoprijatnymi dlja neposredstvennogo ionnogo nagreva vzaimodejstviem puchka s plazmoj, my pristupili k jeksperimentam, v kotoryh dopolnitel'naja radiochastotnaja jenergija nakladyvaetsja s cel'ju vozbuzhdenija ciklotronnyh kolebanij ionov dlja ionnogo nagreva. Rassmotreniju podlezhat ustojchivost' plazmy; plotnost', srednjaja jenergija i maksimal'naja jenergija jelektronov plazmy; i predvaritel'nye rezul'taty po ionnomu nagrevu. Provodjatsja jeksperimenty s pul'sirujushhim jelektronnym puchkom v 10-15 kv i 10 - 15 A, kotoryj inzhektiruetsja vdol' osi magnitnyh probok v'oblast' drejfa, soderzhashhuju H{sub 2} np 10{sup -5}-10{sup -4} torr. Plotnost' jelektronov plazmy ob{sup e}mom v 1 litr obychno sostavljaet 10{sup 12}-10{sup 13} sm{sup -3} i plotnost' poperechnoj jEhnergii obychno sostavljaet 10{sup 15} jev/sm{sup 3}, chto sootvetstvuet temperature poperechnyh jelektronov v 10{sup 2}-10{sup 3} jev. Izmerenie jenergij rentgenovskih luchej ukazyvaet na sushhestvovanie' jelektronov s jenergiej 50-100 kjev. Spad plazmy posle vykljuchenija puchka proishodit v dva jetapa: otnositel'no bystraja poterja jelektronov nizkoj jEhnergii, {tau} Less-Than-Or-Equal-To 1000 mksek, i medlennyj spad jelektronov vysokoj jEhnergii s {tau} = 10-50 msek. Vtoroj jeksperiment provoditsja s temi zhe parametrami jelektronnogo puchka, konfiguraciej magnitnogo polja i diapazonom davlenija. Razmery plazmy okazalis' vdvoe bol'she. Putem vvedenija gaza s pomoshh'ju bystrogo pul'sirujushhego gazovogo klapana polucheny sovershenno razlichnye parametry jEhnergii plazmy, chto takim obrazom opredeljaet gradient davlenija. Gaz, nakachennyj s pomoshh'ju plazmy, sushhestvennym obrazom sokrashhen pri toj zhe samoj plotnosti i jEhnergii plazmy. Desjatikratno vozrastajut srednie i pikovye jelektronnye jEhnergii po otnosheniju k ih ob{sup e}mam pri odinakovoj gazovoj plotnosti. V otdel'nyh sluchajah v poslesvechenii nabljudaetsja ''razryv'' neustojchivosti, chto sootvetstvuet potere nizkoj jEhnergii plazmy. (author)

  17. Design and characteristics of beta-excited X-ray sources; Caracteristiques des sources de rayons X excitees par des particules beta; Konstruktsiya i kharakteristiki beta-vozbuzhdennykh istochnikov rentgenovskikh luchej; Diseno y caracteristicas de las fuentes de rayos X excitadas por particulas beta

    Energy Technology Data Exchange (ETDEWEB)

    Filosofo, I; Reiffel, L; Stone, C A; Voyvodic, L [Physics Division, Armour Research Foundation, Chicago, IL (United States)

    1962-01-15

    The paper reports on recent work on beta-excited X-ray sources. Results of detailed experimental investigation on the X-rays produced by the fission products Pm{sup 147}, Kr{sup 85} and Sr{sup 90} are described. X-ray yields and spectral distributions have been studied for target materials ranging from copper to uranium and in a variety of source-target geometries (transmission target, reflection target, sandwich target, intimate source-target mixtures). To interpret the experimental results, an analytical treatment of the processes involved in X-ray production by beta particles has been developed and is outlined. By taking into account bremsstrahlung, K-shell ionization, and fluorescent X-ray excitation, a convenient mathematical formulation may be derived for photon spectra and yields as functions of maximum {beta}-energy, target thickness and source configuration. The agreement between calculated and experimentally determined yields is excellent and confirms the merit of the analysis. It thus becomes possible to optimize the design of isotopic X-ray sources for specific applications. Kr{sup 85} and Pm{sup 147} prototype sources have been designed and 'their performance in thickness and composition-analysis measurements is discussed. A high level Pm{sup 147} source for industrial radiography has also been designed and its performance, along with the utility of image intensifiers to extend its applicability, is considered. Finally, a general review of potentialities, advantages and limitations of isotopic X-ray sources is given. (author) [French] Le memoire rend compte des recents travaux sur les sources de rayons X excitees par des particules beta. Il donne les resultats d'une etude experimentale detaillee sur les rayons X emis par les produits de fission {sup 147}Pm, {sup 85}Kr et {sup 90}Sr. Les auteurs ont etudie l'emission et la distribution spectrale des rayons X pour des cibles allant du cuivre a l'uranium, et ce dans plusieurs geometries source-cible differentes, a savoir : etude en transmission, en retrodiffusion, en , et enfin avec source et cible intimemement liees. Pour interpreter les resultats des experiences, les auteurs ont mis au point une analyse des processus qui interviennent dans la production des rayons X par les particules beta; ils en font l'expose. En tenant compte du rayonnement de freinage, de l'ionisation de la couche K et de fluorescence provoquee par les rayons X, il est possible de degager une formule mathematique commode pour les spectres et les nombres de photons emis, en fonction de l'energie beta maximum, de l'epaisseur de la cible et de la configuration de la source. En ce qui concerne les nombres de photons emis, les resultats de l'experience concordent parfaitement avec ceux des calculs theoriques, ce qui confirme la valeur de l'analyse. Il devient ainsi possible de mettre au point des sources de rayons X isotopiques repondant aux exigences des applications auxquelles elles sont destinees. On a construit des sources prototypes de {sup 85}Kr et de {sup 147}Pm; les auteurs en etudient l'efficacite pour les mesures d'epaisseur et les analyses de composition. Ils examinent aussi le comportement d'une source de {sup 147}Pm de grande intensite, mise au point pour Le memoire rend compte des recents travaux sur les sources de rayons X excitees par des particules beta. Il donne les resultats d'une etude experimentale detaillee sur les rayons X emis par les produits de fission {sup 147}Pm, {sup 85}Kr et {sup 90}Sr. Les auteurs ont etudie l'emission et la distribution spectrale des rayons X pour des cibles allant du cuivre a l'uranium, et ce dans plusieurs geometries source-cible differentes, a savoir : etude en transmission, en retrodiffusion, en , et enfin avec source et cible intimemement liees. Pour interpreter les resultats des experiences, les auteurs ont mis au point une analyse des processus qui interviennent dans la production des rayons X par les particules beta; ils en font l'expose. En tenant compte du rayonnement de freinage, de l'ionisation de la couche K et de fluorescence provoquee par les rayons X, il est possible de degager une formule mathematique commode pour les spectres et les nombres de photons emis, en fonction de l'energie beta maximum, de l'epaisseur de la cible et de la configuration de la source. En ce qui concerne les nombres de photons emis, les resultats de l'experience concordent parfaitement avec ceux des calculs theoriques, ce qui confirme la valeur de l'analyse. Il devient ainsi possible de mettre au point des sources de rayons X isotopiques repondant aux exigences des applications auxquelles elles sont destinees. On a construit des sources prototypes de {sup 85}Kr et de {sup 147}Pm; les auteurs en etudient l'efficacite pour les mesures d'epaisseur et les analyses de composition. Ils examinent aussi le comportement d'une source de {sup 147}Pm de grande intensite, mise au point pour la radiographie industrielle, ainsi que l'utilite des renforcateurs d'images, qui permettraient d'en etendre le champ d'application. Enfin, les auteurs passent en revue les possibilites, avantages et limites des sources de rayons X isotopiques. [Spanish] La memoria trata de trabajos realizados recientemente acerca de fuentes de rayos X excitadas por particulas beta. Describe los resultados de una minuciosa investigacion experimental sobre los rayos X generados por los productos de fision {sup 147}Pm, {sup 85}Kr y {sup 90}Sr. Los autores han estudiado los rendimientos en rayos X y las distribuciones espectrales correspondientes a materiales de blanco que abarcan del cobre al uranio, para diversas geometrias fuente-blanco (blancos de transmision, blancos de reflexion, blancos ''sandwich'' y mezclas intimas de la fuente y el blanco). Para interpretar los resultados experimentales, los autores idearon un metodo de analisis de los procesos que intervienen en la produccion de rayos X por excitacion mediante particulas beta; dicho metodo se describe en la memoria. Si se tienen en cuenta la radiacion de frenado (Bremsstrahlung), la ionizacion de la capa K y la fluorescencia provocada por los rayos X, puede lograrse una formulacion matematica satisfactoria para calcular los rendimientos y los espectros fotonicos en funcion de la energia {beta} maxima, del espesor del blanco y de la configuracion de la fuente. Los rendimientos calculados concuerdan perfectamente con los determinados por via experimental, lo que confirma la validez del metodo analitico. De esta forma, resulta posible disenar fuentes isotopicas de rayos X que responden optimamente a las exigencias de las aplicaciones a las que van destinadas. Los autores disenaron prototipos de fuentes de {sup 85}Kr y de {sup 147}Pm, y la memoria analiza su eficacia en las mediciones de espesores y el analisis de sustancias compuestas. Tambien disenaron una fuente de {sup 147}Pm de elevada intensidad destinada a la radiografia industrial; la memoria examina su funcionamiento, asi como la utilidad de los intensificadores de imagen que permiten ampliar el campo de aplicaciones de dicha fuente. Los autores terminan su memoria con un examen general de las posibilidades, ventajas y limitaciones de las fuentes isotopicas de rayos X. (author) [Russian] V dokumente izlagayutsya novejshie rezul'taty rabot nad beta-vozbuzhdennymi istochnikami rentgenovskikh luchej. Opisyvayutsya rezul'taty podrobnogo ehksperimental'nogo issledovaniya rentgenovskikh luchej, proizvodimykh produktami deleniya Rt-147, Kg-85 i Sr-90. Vykhod rentgenovskikh luchej i spektral'noe raspredelenie byli izucheny dlya mishenej, postroennykh iz materialov, idushchikh ot medi do urana, a takzhe dlya raznoobraznogo vzaimnogo raspolozheniya istochnika i mishenej: (propuskayushchaya mishen', otrazhayushchaya mishen', 'sloenaya'' mishen', tesnoperemeshannye istochniki i mishen'). Osobenno podrobno byla izuchena smes' iz prometiya-147 s okis'yu samariya dlya vyyasneniya perspektiv ispol'zovaniya istochnika vysokogo urovnya, v kotorom sam prometij-147 yavlyaetsya glavnoj mishen'yu rentgenovskikh luchej. Detektirovanie rentgenovskikh luchej proizvodilos' pri pomoshchi stsintillyatsionnykh i proportsional'nykh schetchikov sovmestno s 256-kanal'nym amplitudnym analizatorom impul'sov. Dlya istolkovaniya ehksperimental'nykh dannykh bylo vyrabotano i opisano analiticheskoe vyrazhenie protsessov obrazovaniya rentgenovskikh luchej beta-chastitsami. Esli uchest' tormoznoe izluchenie, obolochechnuyu K-ionizatsiyu i flyuorestsiruyushchee vozbuzhdenie rentgenovskikh luchej, to mozhno vyvesti podkhodyashchuyu matematicheskuyu formulu dlya opredeleniya spektra i vykhoda fotonov v funktsii ot maksimal'noj beta-ehnergii, tolshchiny misheni i konfiguratsii istochnika. Poluchaetsya otlichnoe sovpadenie raschetnykh rezul'tatov s ehksperimental'no poluchennymi vykhodami, chto podtverzhadaet tsennost' ehtogo sposoba analiza. Takim obrazom otkryvaetsya vozmozhnost' dlya optimizatsii konstruktsii izotopnykh istochnikov rentgenovskikh luchej v otnoshenii tekh ili inykh primenenij. Byli skonstruirovany prototipnye istochniki kriptona-85 i prometiya-147 i obsuzhdayutsya poluchennye s nimi rezul'taty izmerenij tolshchiny i analiza sostava. Byl takzhe skonstruirovan istochnik prometiya-147 vysokogo urovnya dlya promyshlennoj radiografii i obsuzhdayutsya rezul'taty ispol'zovaniya ehtogo istochnika, a takzhe tselesoobraznost' primeneniya usilitelej izobrazheniya, chto dolzhno eshche bol'she rasshirit' oblast' primeneniya ehtogo metoda. Nakonets, daetsya obshchij obzor vozmozhnostej, preimushchestv i ogranichenij izotopnykh istochnikov rentgenovskikh luchej. (author)

  18. Characteristics and fabrication of Geiger-Mueller counters with thin walls made of treated magnesium - Note about the use of araldite; Caracteristiques et fabrication des compteurs Geiger-Muller a paroi mince en magnesium traite - Note sur l'utilisation de l'araldite

    Energy Technology Data Exchange (ETDEWEB)

    Charbonnel, A

    1949-03-01

    This report describes, first, the advantage of magnesium for the manufacturing of Geiger-Mueller counters: suitable for machining and polishing, but strong reactivity with the counter atmosphere in the case of magnesium-rich alloys. Thus, the inside wall of the counter (cylinder of 20 mm diameter and 6 cm length) requires a non-reactive protective coating with excellent sealing properties. The synthetic resin 'araldite' fulfills all these conditions. The second part of the report describes the different steps of the fabrication of magnesium wall counters: lathe work, machining down and chemical polishing of hulls, assembly, tight sealing, pumping, filling-up and control tests. The average service life of these counters is of about 4 months. A note about the use and properties (hardening, mechanical properties, resistance..) of araldite is given in appendix. (J.S.)

  19. Determination of some fundamental characteristics of Geiger-Mueller counters. Applications to the study of delayed particles from cosmic-ray shower; Sur la determination de quelques caracteristiques fondamentales de compteurs de geiger-muller applications a l'etude des particules retardees des gerbes atmospheriques du rayonnement cosmique

    Energy Technology Data Exchange (ETDEWEB)

    Picard, E [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1954-06-15

    After some historic recalls, the different phases of discharge of a Geiger-Mueller counter is studied. It measures, by oscillograph method, the time between the flow of a particle through a determined area of the counter and the response of the associated amplifier. This time length is composed by the latency period and the delay itself which depends on the amplifier sensitivity. The selection of particles which generate a discharge in the studied counter is obtained with a two coincidence counters telescope in which the aperture is limited by four counters in anticoincidence with the first two counters. The measures have been done with different distance values and an overvoltage V{sub s} which was applied to the counter. The dead time of a GM counter is also measured with a delayed coincidences method. The counter pulses which supply the coincidence circuit are delivered directly or with a known and variable delay. This method allows also to study the spurious pulses which are due to the positive ions impact on the counter cathode. Results for counters working in different conditions are given. It describes the system to limit the discharge which induces the increase of the life working of a counter, the decrease of its dead time and the reduction of the number of spurious pulses. In a second part, it describes the system to study the time correlation between different particles of the cosmic ray. An experiment concerning the presence of delayed particles in cosmic showers has permitted to specify the superior limit of this phenomena which is directly connected to the presence of heavy nuclear particles in the cosmic shower. (M.P.)

  20. Physical and Chemical Analysis of the Germinating and Nutritional Properties of Irradiated Wheat; Analyse Physico-Chimique des Caracteristiques Germinatives et Nutritives du Ble Irradie; Fizicheskie i khimicheskie analizy svojstv rosta i pitatel'nykh kachestv obluchennoj pshenitsy; Analisis Fisicoquimico de Trigo Irradiado: Estudio de sus Caracteristicas Germinativas y Nutricionales

    Energy Technology Data Exchange (ETDEWEB)

    Pahissa Campa, J.; Gabarain, R. V.A.; De Pahissa, M. H.H. [Comision Nacional de Energia Atomica (Argentina); Bassa, L. [Junta Nacional de Granos, Buenos Aires (Argentina)

    1966-11-15

    The authors exposed wheat to radiation at various dose levels for the purpose of determining the physical and chemical effects on whole grain (its behaviour as seed) and flour (nutritional value). They used the Surena M.A.G. variety of wheat, which is cultivated in Argentina and was supplied by the National Wheat Board. A Canadian Gamma cell 220 apparatus was employed, equipped with a 13 000-Ci {sup 60}Co source and capable of delivering a dose of approximately 1 Mrad/h. Irradiation was carried out at the following dose levels: 10, 15, 20, 50, 100, 150, 200, 300, 500, 1000, 1500 and 2000 krad. The following analytical values were determined: (a) whole wheat - hectolitric weight, moisture content, percentage of proteins (nitrogen content x 13.5), Zeleny figure, ash content, ability to germinate (two and three days); (b) flour - moisture content, percentage of proteins (nitrogen content x 13.5), Zeleny figure, ash content, alcoholic acidity, maltose content, wet gluten content, dry gluten content, farinograph values (absorption of water, development time, degree of sponginess, Brabender moisture tester), alveograph values (stretch-resistance, stretch, degree and rate of deformation, ratio of stretch-resistance to stretch), extensometer values (work required to stretch dough, stretch-resistance, stretch, ratio of stretch-resistance to stretch), bread-making characteristics (weight of bread, volume of bread and specific volume). The same values were also determined for non-irradiated wheat. Sufficient quantities of wheat were irradiated to permit analyses of samples after different periods of time had elapsed. The analytical values were found to vary with dose, marked differences (with respect to the control sample) being noted in the texture, odour, colour and taste of bread made with wheat that had received the highest doses. To determine changes in nutritional value the irradiated wheat was included in the diet of rats, both immediately following irradiation and after various periods of time had elapsed. The development of the rats, in particular that of their blood picture and bone marrow, was then closely followed. (author) [French] Dans leur plan de travail, les auteurs ont prevu l'irradiation de ble a des doses diverses en vue de determiner les effets physiques et chimiques sur les grains et la farine, le comportement du ble en tant que semence et sa valeur alimentaire; Ils ont utilise la variete Surena M. A.G., qui est cultivee en Argentine et dont des echantillons avaient ete fournis par l'Office national de cereales. Pour l'irradiation, ils se sont servi d'un appareil canadien Gammacell 220, de 13 000 Ci de cobalt-60, fournissant une dose d'environ lMrad/h. Des irradiations ont ete effectuees aux doses suivantes: 10, 15, 20, 50, 100, 150, 200, 300, 500, 1000, 1500 et 2000 krad. On a analyse les echantillons irradies pour determiner les valeurs suivantes: a) pour le ble entier: poids de l'hectolitre, humidite, proteines en pour cent (base azote multipliee par 13, 5), Zeleny, cendres, pouvoir germinatif (deux et trois jours); b) pour la farine : humidite, proteines (base azote multipliee par 13,5), Zeleny, cendres, acidite alcoolique, maltose, gluten humide, gluten sec; procedes utilises: farinographe (absorption d'eau, temps de formation de la pate, degre d'elasticite, valorimetre de Brabender); alveographe (tenacite, extensibilite, travail de deformation, rapport tenacite/extensibilite); extensimetre (force, resistance, extensibilite, rapport resistance/extensibilite); panification (poids du pain, volume du pain et volume specifique). Parallelement, il a ete procede aux memes mesures sur du ble non irradie. Etant donne les quantites irradiees, on a pu conserver des echantillons en vue de proceder a l'analyse des memes parametres apres divers laps de temps. Les diverses valeurs analysees ont accuse des variations en fonction de la dose. En ce qui concerne la texture, l'odeur, la couleur et le gout du pain, les doses les plus fortes ont engendre des differences tres sensibles par rapport a l'echantillon temoin. Pour determiner la valeur alimentaire du grain irradie, les auteurs en ont inclus dans la ration alimentaire de rats, aussitot apres l'irradiation et, par la suite, a divers intervalles. On a suivi l'evolution des animaux et plus particulierement celle de leur systeme sanguin et de leur moelle osseuse. (author) [Spanish] El plan de trabajo contemplo la irradiacion de trigo a distintos niveles de dosis, a fin de determinar los efectos fisicos y quimicos sobre grano entero y harina, su comportamiento como semilla y su valor alimenticio. Se utilizo la variedad Surena M. A.G. que se cultiva en la Republica Argentina, suministrada por la Junta Nacional de Granos. Se empleo para irradiar un Gammacell 220 (Canadiense) provisto de 13 000 Ci de cobalto-60 y que provee una dosis aproximada de 1 Mrad/h. Se han realizado irradiaciones a los siguientes niveles de dosis: 10, 15, 20, 50, 100, 150, 200, 300, 500, 1000, 1500 y 2000 krad. Se determinaron los siguientes valores analiticos de las muestras irradiadas: a) Sobre trigo entero: peso hectolitrico, humedad, proteinas por ciento (base nitrogeno por 13, 5), Zeleny, cenizas, energia germinativa (2 y 3 dias), b) Sobre harina, humedad, proteinas (base nitrogeno por 13, 5), Zeleny, cenizas, acidez alcoholica, maltosa, gluten humedo, gluten seco, farinografo (comprende: absorcion de agua, tiempo de desarrollo de la.masa, grado de aflojamiento: valorimetro Brabender), alveografo (comprende: tenacidad, extensibilidad, trabajo de deformacion, relacion tenacidad/extensibilidad), extensografo (comprende: energia, resistencia, extensibilidad, relacion resistencia/extensibilidad), panificacion (comprende: peso del pan, volumen del pan, y volumen especifico). Paralelamente se realizaron las mismas determinaciones con trigo sin irradiar. Las cantidades irradiadas permitieron conservar muestras para realizar los analisis de los mismos parametros luego de transcurridos diversos lapsos. Se apreciaron distintas variaciones en los valores analiticos determinados, variaciones que dependian de la dosis. En cuanto a la textura, olor, color y sabor del pan, se observaron diferencias sumamente marcadas respecto al testigo, para las dosis mas elevadas. Para evaluar el valor alimenticio del grano irradiado, se emplearon ratas a las cuales se les incluyo en la dieta dicho material. La incorporacion se realizo inmediatamente despues de la irradiacion, y con posterioridad a lapsos variables. Se controlo la evolucion de los animales y fundamentalmente el cuadro hematico y medula osea. (author) [Russian] Pshenicu obluchali razlichnymi dozami s cel'ju opredelit' himicheskoe i fizicheskoe vlijanie obluchenija na celoe zerno (ego povedenie kak semeni) i muku (pishhevaja cennost'). V opyte ispol'zovali raznovidnost' pshenicy Surena M. A. G., kul'tiviruemoj v Argentine, ona byla postavlena Nacional'noj organizaciej po pshenice. Byl primenen pribor kanadskaja gamma-kamera 220 s istochnikom kobal't-60 moshhnost'ju 13 000 kjuri, sposobnym davat' dozu priblizitel'no 1 mrad/chas. Pshenicu obluchali dozami 10, 15, 20, 50,100,150, 200,-300, 500,1000, 1500 i 2000 kilorad. Byli opredeleny sledujushhie analiticheskie velichiny: a) po celomu zernu - ves 1 gektolitra, vlazhnost', procent proteina (soderzhanie azota h 13,5), cifra Zeleny, soderzhanie zoly, sposobnost' k prorastaniju (2 i 3 dnja); b) po muke - vlazhnost', procent proteina (soderzhanie azota h 13,5), cifra Zeleny, soderzhanie zoly, alkogol'naja kislotnost', soderzhanie solodovogo sahara, soderzhanie zhidkoj klejkoviny, soderzhanie suhoj klejkoviny, farintrafi- cheskie velichiny (pogloshhenie vody, vremja razvitija, stepen' poristosti, shhup dlja izmerenija vlazhnosti Brabendera), al'veograficheskie velichiny (soprotivlenie testa raskatyvaniju, rastjagivanie, stepen' i skorost' deformacii, sootnoshenie soprotivlenija na raskatyvanie'i raskatyvanija), velichiny rasshirenija (rabota, trebuemaja dlja raskatyvanija testa, soprotivlenie raskatyvaniju, raskatyvanie, otnoshenie soprotivlenija raskatyvaniju k raskatyvaniju), harakteristiki, kasajushhiesja vypechki hleba (ves, ob{sup e}m i udel'nyj ob{sup e}m hleba). Te zhe samye velichiny byli opredeleny takzhe dlja neobluchennoj pshenicy. Dostatochnoe kolichestvo pshenicy bylo oblucheno s tem, chtoby mozhno bylo osushhestvit' analizy obrazcov po istechenii razlichnyh periodov vremeni. Byli najdeny analiticheskie velichiny, menjajushhiesja s dozoj, otmecheny razlichija (s uchetom kontrol'nogo obrazca), registriruemye v teksture, aromate, cvete i vkuse hleba, izgotovlennogo iz pshenicy, obluchennoj samymi bol'shimi dozami. Dlja opredelenija izmenenij v pitatel'nyh svojstvah obluchennaja pshenica byla vkljuchena v racion krys kak neposredstvenno posle obluchenija, tak i spustja nekotoroe vremja. Posle jetogo byli provedeny tshhatel'nye nabljudenija za razvitiem krys, v chastnosti za razvitiem ih kartiny krovi i kostnogo mozga. (author)

  1. Radio-induced breast cancers exhibiting aggressive anatomo-pathological characteristics: retrospective study of the long-term follow-up committee of the French Society of Child Cancers; Cancers du sein radio-induits presentant des caracteristiques anatomopathologiques agressives: etude retrospective du comite de suivi a long terme de la Societe francaise des cancers de l'enfant

    Energy Technology Data Exchange (ETDEWEB)

    Demoor, C.; Mahe, M.A.; Supiot, S. [ICO Rene-Gauducheau, Nantes (France); Vathaire, F. de [Inserm UMRS 1018, institut de cancerologie Gustave-Roussy, Villejuif (France); Oberlin, O. [Institut de cancerologie Gustave-Roussy, Villejuif (France); Noel, G. [Centre Paul-Strauss, Strasbourg (France); Brillaud, V. [Institut Bergonie, Bordeaux (France); Bernier, V. [Centre Alexis-Vautrin, Nancy (France); Laprie, A. [Institut Claudius-Regaud, Toulouse (France); Claude, L. [Centre Leon-Berard, Lyon (France)

    2011-10-15

    The authors report an analysis of clinical-pathological characteristics of radio-induced breast cancers registered in six French centres. 82 breast cancers concerning 75 women have been analyzed in terms of patient age, cancer type, interval between both cancers. It appears that radio-induced cancers exhibited significantly more aggressive characteristics. The screening of young women at risk is therefore recommended for an early diagnosis and treatment. Short communication

  2. Tracking techniques for the method of characteristics applied to the neutron transport problem in multi-dimensional domains; Techniques de tracage pour la methode des caracteristiques appliquee a la resolution de l'equation du transport des neutrons en domaines multi-dimensionnels

    Energy Technology Data Exchange (ETDEWEB)

    Fevotte, F

    2008-10-15

    In the past years, the Method of Characteristics (MOC) has become a popular tool for the numerical solution of the neutron transport equation. Among its most interesting advantages are its good precision over computing time ratio, as well as its ability to accurately describe complicated geometries using non structured meshes. In order to reduce the need for computing resources in the method of characteristics, we propose in this dissertation two lines of improvement. The first axis of development is based on an analysis of the transverse integration technique in the method of characteristics. Various limitations have been discerned in this regard, which we intend to correct by proposing a new variant of the method of characteristics. Through a better treatment of material discontinuities in the geometry, our aim is to increase the accuracy of the transverse integration formula in order to decrease the computing resources without sacrificing the quality of the results. This method has been numerically tested in order to show its interest. Analysing the numerical results obtained with this new method also allows better understanding of the transverse integration approximations. Another improvement comes from the observation that industrial reactor cores exhibit very complex structures, but are often partly composed of a lattice of geometrically identical cells or assemblies. We propose a systematic method taking advantage of repetitions in the geometry to reduce the storage requirements for geometric data. Based on the group theory, this method can be employed for all lattice geometries. We present some numerical results showing the interest of the method in industrial contexts. (author)

  3. Study of radon emanation from uranium mill tailings. Relations between radon emanating power and physicochemical properties of the material; Etude de l'emanation du radon a partir de residus de traitement de minerais d'uranium. Mise en evidence de relations entre le facteur d'emanation et les caracteristiques du materiau

    Energy Technology Data Exchange (ETDEWEB)

    Pellegrini, D

    1999-07-01

    The uranium extraction from ores leads to large amounts of mill tailings still containing radionuclides, such as thorium-230 and radium-226, which generate radon-222. Without protective action, radon exposition may be high enough to cause concern for health of populations living in the vicinity of an uranium mill tailings disposal. This exposition pathway has therefore to be taken into account in the radiological impact studies. The emanating power, i.e. the part of radon atoms which escape from the solid particles, is directly involved in the radon source term evaluation. It may be determined for a given material by laboratory measurements. Emanating powers from 0.08 to 0.33 have been obtained for mill tailings from Jouac (Limousin, France), at various moisture contents. In order to reduce the relations of dependence between some of the emanation parameters, more simple phases, kaolinite and polymeric resins, have been studied. Those experiments have led us to the selection of the mechanisms and the parameters to consider for the development of an emanation modelling. The whole of the results obtained point out the radon sorption, in various proportions depending on the materials. The moisture content influence on the emanation from materials containing fine particles have been confirmed: the emanation increases with this parameter until a continuous water film surrounding the particles have been formed, and then become constant. This 'water effect' occurs in a moisture content range, which depends on the material porosity. Elsewhere, the presence of amorphous phases may led to a high radon emanation. (author)

  4. Study of the carbonaceous fraction of the atmospheric aerosol in Chamonix and St Jean de Maurienne: seasonal evolutions, source and chemical characteristics; Etude de la fraction carbonee de l'aerosol atmospherique a Chamonix et St Jean de Maurienne: evolutions saisonnieres, sources et caracteristiques chimiques

    Energy Technology Data Exchange (ETDEWEB)

    Aymoz, G.

    2005-03-15

    The atmospheric aerosols play an important role in the earth climatic system. They are also at the origin of air pollution problems in urban areas. However, their influence on the global climactic change, as well as their chemical properties in urban zone, is still very poorly known. One of the main reasons to that is the lack of information on one of the major components of aerosol, the carbonaceous matter. This work focuses on a better knowledge of this particulate carbonaceous matter. This study presents measurements of carbonaceous matter (OC and EC) in aerosol (PM10) performed within the framework of the program POVA, between February 2001 and June 2003 in Chamonix and St Jean de Maurienne (French Alps). This series represents one of the first of this type for basic sites of alpine valleys, characterized by emissions located in the bottom of the valleys and strong temperature inversions in winter, limiting the dispersion of pollutants. The POVA program, centred on the study of air pollution in these valleys, was proposed following the closing of the 'Tunnel du Mont Blanc', in 1999. One of the main objectives was to evaluate the sources of pollution by particles, in particular the share due to the international heavy duty traffic. We could establish that, on the two sites and while the international heavy duty traffic was not restored in the Chamonix Valley, this source represented approximately a third of the observed mass of particles, and was at the origin of a weaker fraction of the carbonaceous matter mass. The extremely primary character of the carbonaceous matter is a remarkable specificity of our sites. The source of carbonaceous matter represented by light vehicles emissions could not be studied. Then, it appears that combustion of biomass (probably from fireplaces) plays an important role, increased in the case of low temperatures, on the levels of pollution by particles. Lastly, the potential impact of the semi-volatile matter condensation at the low temperatures remains an assumption to be tested. On a more general point of view, several results can be pointed out concerning the organic matter: 1. The conversion factor of organic carbon mass to organic matter mass is undoubtedly very variable for a given site (in particular, its variability is probably largely higher than 0,2). 2. The generally allowed assumptions for the calculation of the secondary fraction of OC appeared false in the case of our study, and the method seems in the general case very dubious. 3. The soluble fraction of OC is very important on our sites. The primary source of biomass combustions is an important primary source of WSOC. This result is in disagreement with the general assumption that WSOC is mostly with a secondary origin. (author)

  5. Characteristics and fabrication of Geiger-Mueller counters with thin walls made of treated magnesium - Note about the use of araldite; Caracteristiques et fabrication des compteurs Geiger-Muller a paroi mince en magnesium traite - Note sur l'utilisation de l'araldite

    Energy Technology Data Exchange (ETDEWEB)

    Charbonnel, A

    1949-03-01

    This report describes, first, the advantage of magnesium for the manufacturing of Geiger-Mueller counters: suitable for machining and polishing, but strong reactivity with the counter atmosphere in the case of magnesium-rich alloys. Thus, the inside wall of the counter (cylinder of 20 mm diameter and 6 cm length) requires a non-reactive protective coating with excellent sealing properties. The synthetic resin 'araldite' fulfills all these conditions. The second part of the report describes the different steps of the fabrication of magnesium wall counters: lathe work, machining down and chemical polishing of hulls, assembly, tight sealing, pumping, filling-up and control tests. The average service life of these counters is of about 4 months. A note about the use and properties (hardening, mechanical properties, resistance..) of araldite is given in appendix. (J.S.)

  6. A Double Slow Neutron Spectrometer; Spectrometre double pour neutrons lents; Dvojnoj spektrometr medlennykh nejtronov; Espectrometro doble para neutrones lentos

    Energy Technology Data Exchange (ETDEWEB)

    Bondarenko, I I; Liforov, V G; Nikolaev, M N; Orlov, V V; Parfenov, V A; Semenov, V A; Smirnov, V I; Turchin, V F [Fehi, Moscow, SSSR (Russian Federation)

    1963-01-15

    The neutron spectrometer described in the paper is intended for measurements of the angular and energy distribution of monochromatic slow neutrons, inelasticaily scattered by liquid and solid bodies. Experiments of this type permit detailed information to be obtained concerning the dynamics of the atoms in various aggregate states of a substance. The spectromeeter is based on the time-of-flight method. The pulse source of neutrons is the IBR (1) reactor. A mechanical interrupter, rotating synchronously with the disc of the IBR and having a prescribed phase shift, serves as the monochromator. A special phasing system ensures a phasee stability better than 0.5{sup o}. The neutrons scattered by the sample are recorded by a scintillation detector set at a given angle to the neutron beam. The resolving power of the spectrometer is - 15 {mu}s/m. The paper gives a detailed description of the construction of the spectroscope and its characteristics. (author) [French] Le spectrometre neutronique decrit dans le memoire est destine a mesurer la distribution en energie, la distribution angulaire et la diffusion inelastique des neutrons lents monochromatiques dans des liquides et des solides. Les experiences de ce genre permettent d'obtenir des renseignements detailles sur la dynamique des atomes dans de divers etats de la matiere. Le spectrometre est fonde sur la mesure du temps de vol. Comme source puisee de neutrons on a utilise le reacteur IBR-1. Le systeme monochromateur etait constitue par un interrupteur mecanique en rotation synchronisee avec celle du disque du reacteur IBR, avec un dephasage determine. Un dispositif special de dephasage assure la stabilite de la phase a 0,5{sup o} pres. La diffusion des neutrons par l'echantillon est enregistree a l'aide d'un detecteur a scintillations dispose sous un angle determine par rapport au faisceau de neutrons. Le pouvoir de resolution du spectrometre est d'environ 15 {mu}s/m. Les auteurs decrivent en detail la construction du

  7. Etude des melanges co-continus d'acide polylactique et d'amidon thermoplastique (PLA/TPS)

    Science.gov (United States)

    Chavez Garcia, Maria Graciela

    Les melanges co-continus sont des melanges polymeriques ou chaque composant se trouve dans une phase continue. Pour cette raison, les caracteristiques de chacun des composants se combinent et il en resulte un materiau avec une morphologie et des proprietes particulieres. L'acide polylactique (PLA) et l'amidon thermoplastique (TPS) sont des biopolymeres qui proviennent de ressources renouvelables et qui sont biodegradables. Dans ce projet, differents melanges de PLA et TPS a une haute concentration de TPS ont ete prepares dans une extrudeuse bi-vis afin de generer des structures co-continues. Grace a la technique de lixiviation selective, le TPS est enleve pour creer une structure poreuse de PLA qui a pu etre analysee au moyen de la microtomographie R-X et de la microscopie electronique a balayage MEB. L'analyse des images 2D et 3D confirme la presence de la structure co-continue dans les melanges dont la concentration en TPS. se situe entre 66% et 80%. L'effet de deux plastifiants, le glycerol seul et le melange de glycerol et de sorbitol, dans la formulation de TPS est etudie dans ce travail. De plus, nous avons evalue l'effet du PLA greffe a l'anhydride maleique (PLAg) en tant que compatibilisant. On a trouve que la phase de TPS obtenue avec le glycerol est plus grande. L'effet de recuit sur la taille de phases est aussi analyse. Grace aux memes techniques d'analyse, on a etudie l'effet du procede de moulage par injection sur la morphologie. On a constate que les pieces injectees presentent une microstructure heterogene et differente entre la surface et le centre de la piece. Pres de la surface, une peau plus riche en PLA est presente et les phases de TPS y sont allongees sous forme de lamelles. Plus au centre de la piece, une morphologie plus cellulaire est observee pour chaque phase continue. L'effet des formulations sur les proprietes mecaniques a aussi ete etudie. Les pieces injectees dont la concentration de TPS est plus grande presentent une moindre

  8. Properties of low content uranium-molybdenum alloys which may be used as nuclear fuels; Proprietes des alliages uranium-molybdene de faibles teneurs utilisables comme materiaux combustibles

    Energy Technology Data Exchange (ETDEWEB)

    Lehmann, J; Decours, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    sont presentees les caracteristiques metallurgiques des alliages uranium-molybdene de teneurs comprises entre 0,5 et 3 pour cent en poids de molybdene. Certains de ces alliages etant utilises dans les piles de puissance EdF, nous indiquons brievement les conditions de fonctionnement demandees aux materiaux combustibles: temperature maximum, gradient de temperature et pression externe. Dans une premiere partie sont etudiees les proprietes structurales des alliages en correlation avec les cinetiques des transformations de phases, nous decrivons les incidences de differents facteurs physico-metallurgiques sur la morphologie et sur la structure cristalline des materiaux: - conditions de solidification et heredite de la structure {gamma}, - vitesse de refroidissement au passage des points de transformation - suppression ou non de la transformation intermediaire {gamma} {yields} {beta} Dans une seconde partie, nous indiquons comment la connaissance des processus des transformations de phase a permis de definir les conditions d'elaboration optimales de ces materiaux sous forme de tubes de combustibles destines aux reacteurs EdF: conditions de coulee traitement de refroidissement controle, soudabilite. Dans une troisieme partie, nous etudions la stabilite thermique au cours de paliers de longue duree a haute temperature et de cycles, dans les deux domaines du diagramme d'equilibre {alpha} + {gamma}, {beta} + {gamma}; les influences de la morphologie (en particulier des deux types de pseudo-grains {alpha} observes) et de la vitesse de refroidissement lors du passage des points de transformation sont discutees. Dans une quatrieme partie, les proprietes mecaniques sont discutees resistance a la traction, resistance au fluage, resilience. Ces proprietes peuvent etre egalement influencees par l'heredite de la structure {gamma} et par la vitesse de refroidissement subie par l'alliage. En conclusion, nous developpons les raisons qui ont motive le choix de certains de ces alliages

  9. Stainless-Steel-Gadolinium Alloys; Alliages Acier Inoxydable-Gadolinium; Splavy iz nerzhaveyushchej stali i gadoliniya; Aleaciones de Acero Inoxidable-Gadolinio

    Energy Technology Data Exchange (ETDEWEB)

    Copeland, M.; Kato, H. [Albany Metallurgy Research Center, Bureau Of Mines, United States Department of the Interior, Albany, OR (United States)

    1964-06-15

    mineures ont une grande influence sur les structures resultant de traitements equilibrants et sur les possibilites de transformation des aciers. Lorsque le gadolinium est melange a de l 'acier au chrome et au nickel, deux phases mineures, Fe{sub 9}Gd et Ni{sub 7}Gd, fondent a 1080 Degree-Sign C, ce qui impose une limite superieure aux temperatures de traitement a chaud et de transformation. Les auteurs ont pu facilement transformer des alliages comprenant jusqu'a 5 Degree-Sign Io en poids de gadolinium et determiner leurs caracteristiques mecaniques et leur resistance a la corrosion. Ils n'ont observe aucun changement dans les caracteristiques mecaniques de l'acier ou sa resistance a la corrosion par l'eau chaude, lorsqu'ils lui ont ajoute'jusqu'a 3% en poids de gadolinium. En raison des limites imposees aux temperatures de transformation des aciers au chrome et au nickel par le point de fusion des phases mineures, les auteurs ont etudie les effets du gadolinium sur des aciers au chrome. Ils ont releve une seule phase mineure qui fond a 1320 Degree-Sign C en etudiant l 'isoplethe du gadolinium a 10% en poids dans l 'alliage chrome-fer-gadolinium. Cette propriete permettrait d'equilibrer et de transformer ces aciers au gadolinium aux temperatures auxquelles on opere normalement. (author) [Spanish] En vista de la excelente resistencia a la corrosion de los aceros inoxidables y del interes que presenta el gadolinio como veneno nuclear, se han estudiado aleaciones de esos dos metales. El gadolinio fue aleado con aceros inoxidables de tipo AISI-304 y al cromo, y se estudiaron las relaciones de fase, la facilidad de trabajo y las propiedades de estas aleaciones. Se observo que en las aleaciones que contienen bajos porcentajes de gadolinio, los puntos de fusion de las fases menores ejercen un efecto muy marcado sobre las estructuras resultantes de los tratamientos de equilibracion y sobre la facilidad de trabajo de los afceros. Cuando se alea el gadolinio con acerce al cromo

  10. Behaviour of a pre-stressed concrete pressure-vessel subjected to a high temperature gradient; Comportement d'un caisson en beton precontraint soumis a un gradient de temperature eleve

    Energy Technology Data Exchange (ETDEWEB)

    Dubois, F [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Bonvalet, Ch; Dawance, G; Marechal, J C [Centre Experimental de Recherches et d' Etudes du Batiment et des Travaux Publics (CEBTP), 76 - Harfleur (France)

    1965-07-01

    'elasticite dynamique a diminue de moitie mais le beton conserve de bonnes caracteristiques mecaniques. Enfin, des fissures ayant 8 a 12 cm de profondeur et 2 a 3 mm de largeur sont apparues dans la zone ou le beton n'etait pas precontraint. Les resultats obtenus permettent d'une part, de definir un programme d'essais ulterieurs, d'autre part, de proposer une methode de calcul des caissons en beton precontraint. (auteurs)

  11. Behaviour of a pre-stressed concrete pressure-vessel subjected to a high temperature gradient; Comportement d'un caisson en beton precontraint soumis a un gradient de temperature eleve

    Energy Technology Data Exchange (ETDEWEB)

    Dubois, F. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Bonvalet, Ch.; Dawance, G.; Marechal, J.C. [Centre Experimental de Recherches et d' Etudes du Batiment et des Travaux Publics (CEBTP), 76 - Harfleur (France)

    1965-07-01

    suivant leur position par rapport a la surface interieure. Le module d'elasticite dynamique a diminue de moitie mais le beton conserve de bonnes caracteristiques mecaniques. Enfin, des fissures ayant 8 a 12 cm de profondeur et 2 a 3 mm de largeur sont apparues dans la zone ou le beton n'etait pas precontraint. Les resultats obtenus permettent d'une part, de definir un programme d'essais ulterieurs, d'autre part, de proposer une methode de calcul des caissons en beton precontraint. (auteurs)

  12. Spectra theory for nuclei with closed shells (1962); Theorie des spectres des noyaux a couches completes (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Gillet, V [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1962-07-01

    second approximation which alone leads to a region of optimum agreement identical for both carbon and oxygen. An excellent general agreement is obtained with the known spectra of these two nuclei. The importance of higher order terms in the calculation of the 3{sup -} and 5{sup -} collective states for calcium 40 is demonstrated; furthermore it is possible to explain these levels only by the second approximation. Certain forecasts are made using the effective forces thus found. (author) [French] On applique une theorie unifiee des spectres des noyaux a couches completes, fondee sur les excitations elementaires particule-trou de ces systemes, a l'etude du carbone 12, de l'oxygene i6 et du calcium.40. Deux approximations sont utilisees. La premiere consiste a diagonaliser l'interaction residuelle a deux corps dans un sous-espace limite de configurations a une particule et un trou. Sa validite repose sur l'energie importante exigee pour l'excitation d'une paire particule-trou. La seconde approximation consiste a resommer la sous-serie infinie des diagrammes particule-trou. Elle est equivalente a la methode de Hartree-Fock dependante du temps ou a la methode des Quasi-Bosons. Son domaine de validite, dans le cas nucleaire, n'est pas bien compris. Les diagrammes sommes sont preponderants a la limite des fortes densites, alors que la densite nucleaire est de l'ordre de l'unite. La violation des Principe de Pauli, dans cette approximation, n'est justifiee que si le nombre de paires excitees est petit par rapport au nombre d'etats de particule disponibles; or, dans les noyaux legers les degenerescences des couches sont petites. Neanmoins cette approximation qui postule l'existence d'un champ nucleaire moyen, lentement variable dans le temps par rapport aux periodes des nucleons a le merite d'etre self-consistante, de donner des etats propres orthogonaux a l'etat non physique du centre de masse et d'ameliorer le calcul des regles de somme. Pour determiner et limiter le role de la

  13. Physico-chemical and mechanical modifications of polyethylene and polypropylene by ion implantation, micro-wave plasma, electron beam radiation and gamma ray irradiation; Modifications physico-chimiques et mecaniques du polyethylene et du polypropylene par implantation ionique, plasma micro-ondes, bombardement d`electrons et irradiation gamma

    Energy Technology Data Exchange (ETDEWEB)

    Liao, J D

    1995-03-29

    A polyolefin surface becomes wettable when treated by micro-wave plasma or low-dose nitrogen ion implantation. A short time argon plasma treatment is sufficient to obtain polarizable peroxides on a polyolefin. X-ray photoelectron spectroscopy analyses, paramagnetic electronic resonance analyses, peroxides decomposition, wettability measurements and infrared active spectra analyses have shown that oxidized structures obtained from different treatment techniques play an important role in the interpretation of surface chemical properties of the polymer. Micro-wave plasma treatment, and in particular argon plasma treatment, yields more polarizable groups than ion implantation and is interesting for grafting. Hardness and elasticity modulus, measured by nano-indentation on a polyolefin, increase with an appropriate ion implantation dose. A 1.4 x 10{sup 17} ions.cm{sup -2} dose can multiply by 15 the hardness of high molecular weight polyethylene, and by 7 the elasticity modulus for a 30 nm depth. The viscous-plastic to quasi-elastic transition is shown. The thickness of the modified layer is over 300 nm. The study of friction between a metal sphere and a polyethylene cupula shows that ion implantation in the polymer creates a reticulated hard and elastic layer which improves its mechanical properties and reduces the erosion rate. Surface treatments on polymers used as biomaterials allow to adapt the surface properties to specific applications. 107 refs., 66 figs., 19 tabs., 4 annexes.

  14. Mechanical design of a free-wheel clutch for the thermal engine of a parallel hybrid vehicle with thermal and electrical power-train; Conception mecanique d'un accouplement a roue libre pour le moteur thermique d'un vehicule hybride parallele thermique et electrique

    Energy Technology Data Exchange (ETDEWEB)

    Santin, J.J.

    2001-07-01

    This thesis deals with the design of a free-wheel clutch. This unit is intended to replace the automated dry single-plate clutch of a parallel hybrid car with thermal and electric power-train. Furthermore, the car is a single shaft zero emission vehicle fitted with a controlled gearbox. Chapter one focuses on the type of hybrid vehicle studied. It shows the need to isolate the engine from the rest of the drive train, depending on the driving conditions. Chapter two presents and compares the two alternatives: automated clutch and free-wheel. In order to develop the free-wheel option, the torsional vibrations in the automotive drive line had to be closely studied. It required the design of a specific modular tool, as presented in chapter three, with the help of MATLAB SIMULINK. Lastly, chapter four shows how this tool was used during the design stage and specifies the way to build it. The free-wheel is then to be fitted to a prototype hybrid vehicle, constructed by both the LAMIH and PSA. (author)

  15. Thermodynamical study of the vanadium-hydrogen system. The hydrogen effect on the mechanical properties of V-4Cr-4Ti and V-5Cr-5Ti alloys; Etude thermodynamique du systeme vanadium-hydrogene. Effets de l'hydrogene sur les proprietes mecaniques des alliages V-4Cr-4Ti et V-5Cr-5Ti

    Energy Technology Data Exchange (ETDEWEB)

    Coulombeaux, O

    1998-07-01

    In the framework of the international research programs on fusion reactors, the vanadium alloys are among the most appropriate candidate to constitute the first wall. The author deals with the specific alloys V-4Cr-4Ti and V-5Cr-5Ti and study the hydrogen diffusion. Experimental results show that the induced hydrogen concentration in the sample by diffusion is higher, for the same partial pressure of exposure, in the case of the alloy than for the pure vanadium. He shows that this result can be explainedby the trapping for which the hydrogen is trapped by the titanium. (A.L.B.)

  16. Creep behavior and evolution of microstructure of modified Grade 91 welded joint after short term exposure at 500 deg C; Fluage a 500 deg C d'un joint soude d'un acier 9Cr-1Mo modifie. Evolution de la microstructure et comportement mecanique

    Energy Technology Data Exchange (ETDEWEB)

    Vivier, F.

    2009-03-15

    With the increase in worldwide energy demand, the nuclear industry is a way of producing electricity on a large scale and to answer to this need. For the design of a new generation of fission nuclear reactors and among six chosen fission reactor systems, France develops in particularly the Very High Temperature Reactor (VHTR) concept. This implies the use of materials that are more and more resistant to high temperature for long-term exposure. AREVA focuses on materials already used in fossil-fuel power plant, so that the mechanical behaviour of Grade 91 (Fe{sub 9}Cr{sub 1}MoNbV) has to be investigated. This ferritic-martensitic steel is considered to be a potential candidate for welded components. Such structures are combined with welded joints, which have to be studied. Three industrial partners (AREVA, CEA, EDF) have launched a study with the Centre des Materiaux in order to investigate the creep of welded joint of Grade 91. The aim of this work is to complete the available database about the mechanical behaviour of Grade 91, base metal and welded joint, during creep tests performed at 500 C up to 4500 h exposure. Thermal aging tests, tensile tests, and creep tests were performed at 450 C and 500 C using both base metal and cross-weld samples. Several geometries of cross-weld creep specimens were tested. The microstructure has not remarkably changed after tests concerning both nature and size of precipitates, and the characteristic size of the matrix sub-structure. The creep damage is not developed in the ruptured specimens after creep tests. Only little damage by cavity nucleation and growth was found in the creep specimens. Creep fracture at 500 C takes places by viscoplastic flow, contrary to tests performed at 625 C where the creep-induced damage governs the creep rupture at least for long-term lifetime. From creep curves of base metal and cross-weld specimens, a phenomenological model is proposed. The flow rule is a Norton power law with a stress exponent of 19 in the case of base metal and 18 in the case of welded joint. These high values of Norton exponent indicate the existence of internal stress and suggest that the mechanism which governs the creep deformation might be dislocation glide. The rupture of cross-weld creep specimens takes place in the weld metal, whereas it takes place in the base metal after tensile tests. The heat-affected zone has no obvious role in the mechanical strength of cross-weld specimens at 500 C. In this case, the creep behaviour of the weld metal can be deduced from a combination of the welded joint behaviour and the base metal behaviour. These were identified from experimental creep curves. Another method to determine the weld metal behaviour is to fit the model parameters on creep curves obtained from modified specimens used to test only the weld metal. These results are consistent with open literature data. The proposed model allows determination of a rupture time for longer-term exposure with simple equations and with a good agreement with recent results from CEA. (author)

  17. Metallurgical and mechanical parameters controlling alloy 718 stress corrosion cracking resistance in PWR primary water; Facteurs metallurgiques et mecaniques controlant l'amorcage de defauts de corrosion sous contrainte dans l'alliage 718 en milieu primaire des reacteurs a eau sous pression

    Energy Technology Data Exchange (ETDEWEB)

    Deleume, J

    2007-11-15

    Improving the performance and reliability of the fuel assemblies of the pressurized water reactors requires having a perfect knowledge of the operating margins of both the components and the materials. The choice of alloy 718 as reference material for this study is justified by the industrial will to identify the first order parameters controlling the excellent resistance of this alloy to Stress Corrosion Cracking (SCC). For this purpose, a specific slow strain rate (SSR) crack initiation test using tensile specimen with a V-shaped hump in the middle of the gauge length was developed and modeled. The selectivity of such SSR tests in simulated PWR primary water at 350 C was clearly established by characterizing the SCC resistance of nine alloy 718 thin strip heats. Regardless of their origin and in spite of a similar thermo-mechanical history, they did not exhibit the same susceptibility to SCC crack initiation. All the characterized alloy 718 heats develop oxide scale of similar nature for various exposure times to PWR primary medium in the temperature range [320 C - 360 C]. {delta} phase precipitation has no impact on alloy 718 SCC initiation behavior when exposed to PWR primary water, contrary to interstitial contents and the triggering of plastic instabilities (PLC phenomenon). (author)

  18. Experimental study of chemical-mechanical coupling during percolation of reactive fluid through rocks under stress, in the context of the CO{sub 2} geological sequestration; Etude experimentale du couplage chimie-mecanique lors de la percolation d'un fluide reactif dans des roches sous contrainte, dans le contexte de la sequestration geologique du CO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Le Guen, Y

    2006-10-15

    CO{sub 2} injection into geological repositories will induce chemical and mechanical instabilities. The study of these instabilities is based on experimental deformation of natural rock samples under stress, in the presence of fluids containing, or not, dissolved CO{sub 2}. Triaxial cells used for the experiments permitted an independent control and measurement of stress, temperature, fluid pressure and composition. Vertical strains were measured during several months, with a resolution of 1.10{sup -12} s{sup -1} on the strain rate. Simultaneously, fluids were analysed in order to quantify fluid-rock interactions. For limestone samples, percolation of CO{sub 2}-rich fluids increases strain rate by a factor 1.7 up to 5; on the other hand, sandstone deformation remained almost the same. Increase in strain rate with limestone samples was explained by injected water acidification by the CO{sub 2} which increases rock solubility and reaction kinetics. On the opposite, small effect of CO{sub 2} on quartz explains the absence of deformation. X-ray observations confirmed the importance of rock composition and structure on the porosity evolution. Numerical simulations of rock elastic properties showed increasing shear stress into the sample. Measured deformation showed an evolution of reservoir rocks mechanical properties. It was interpreted as the consequence of pressure solution mechanisms both at grains contacts and on grain free surfaces. (author)

  19. Genesis of the microstructures during friction stir welding of aluminium alloys of the series 2000 and 5000 and resulting mechanical behavior; Genese des microstructures lors du soudage par friction malaxage d'alliages d'aluminium de la serie 2000 et 5000 et comportement mecanique resultant

    Energy Technology Data Exchange (ETDEWEB)

    Genevois, C.

    2004-09-15

    The 2024 alloy (Al-Cu-Mg) is used for minimizing the weight of structural components in the transportation industry. However, this alloy is not easy to weld by traditional techniques. Friction stir welding (FSW) is a recently developed solid state process which removes the solidification defects. In this study, the microstructures of FSW welds of this alloy were finely characterized by SAXS, DSC, TEM, SEM, EBSD and optical microscopy. In order to highlight the interactions between deformation, precipitation and recrystallization, which all take place during the welding of the 2024 alloy, model experiments were carried out as well as a comparative study between the alloys 5251 and 2024. The combination of the welding characterisation and the model experiments allow to define the metallurgical phenomena controlling the mechanical strength of the welded joints and their microstructure. In addition, a detailed characterisation of the mechanical behaviour of the welded joints was carried out, validated by a finite element model. (author)

  20. Study and comparison of some methods for calculating the transmission factor of a potential barrier in quantum mechanics (1963); Etude et comparaison de quelques methodes de calcul du facteur de transmission d'une barriere de potentiel en mecanique quantique (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Jamet, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    The author formulates two accurate methods for the calculation of the transmission coefficient of a one-dimensional potential barrier. The principles of these methods are. expressed in a symmetrical form with respect to the two sides of the potential barrier; this constitutes a proof of the fact that the transmission coefficient is path direction independent. The numerical application is carried out on several examples and the results are compared to those provided by the WKB method. (author) [French] L'auteur formule deux methodes exactes pour calculer le coefficient de transmission d'une barriere de potentiel unidimensionnelle. Les principes de ces methodes s'enoncent sous forme symetrique par rapport aux deux cotes de la barriere de potentiel, ce qui constitue une demonstration du fait que le coefficient de transmission est independant du sens de parcours. L'application numerique est faite sur quelques exemples et les resultats sont compares a ceux fournis par la methode B KW. (auteur)

  1. Coupling of a reservoir model and of a poro-mechanical model. Application to the study of the compaction of petroleum reservoirs and of the associated subsidence; Couplage d'un modele de gisement et d'un modele mecanique. Application a l'etude de la compaction des reservoirs petroliers et de la subsidence associee

    Energy Technology Data Exchange (ETDEWEB)

    Bevillon, D.

    2000-11-30

    The aim of this study is to provide a better description of the rock contribution to fluid flows in petroleum reservoirs. The production of oil/gas in soft highly compacting reservoirs induces important reduction of the pore volume, which increases oil productivity. This compaction leads to undesirable effects such as surface subsidence or damage of well equipment. Analysis of compaction and subsidence can be performed using either engineering reservoir models or coupled poro-mechanical models. Poro-mechanical model offers a rigorous mechanical framework, but does not permit a complete description of the fluids. The reservoir model gives a good description of the fluid phases, but the description of the mechanic phenomenon is then simplified. To satisfy the set of equations (mechanical equilibrium and diffusivity equations), two simulators can be used together sequentially. Each of the two simulators solves its own system independently, and information passed both directions between simulators. This technique is usually referred to the partially coupled scheme. In this study, reservoir and hydro-mechanical simulations show that reservoir theory is not a rigorous framework to represent the evolution of the high porous rocks strains. Then, we introduce a partially coupled scheme that is shown to be consistent and unconditionally stable, which permits to describe correctly poro-mechanical theory in reservoir models. (author)

  2. Experimental study and mechanical modelling of the effects of water-driving in an oil saturated chalk. Application to the petroleum industry; Etude experimentale et modelisation mecanique des effets du balayage a l'eau dans une craie saturee d'huile. Application a l'industrie petroliere

    Energy Technology Data Exchange (ETDEWEB)

    Mata, C.

    2001-01-01

    The production of hydrocarbons may sometimes lead to compaction of the oil-reservoir layers with substantial collapse of the soil surface; this mechanism is usually mentioned as Subsidence. Classical remedy to this problem is to sustain the fluid pressure with the help of water injection. However, in presence of high porosity chalk (porosity > 30%), this technique does not give effective results: the subsidence rate at North Sea reservoirs (Ekofisk field), after injection, has remained unchanged. Some justify the subsistence in the chalk as caused by phenomena of dissolution of the carbonates; others think it is connected to the destruction of capillary menisci. In this research, we follow this second approach. This study is finalized to a better understanding of the compaction mechanisms in pure carbonates when water is injected. This is done by proposing -in micro-scale first and in macro-scale after- a physical model that agrees with empirical observations. In order to meet this target, IFP skills and experience in physical and chemical measurements (taken before, after and during mechanical tests) have proficiently joined ENPC laboratory (CERMMO) knowledge of micro and macro modelling. The soft rock studied is a Paris basin's white chalk (Craie de Guerville). Its physical and chemical characterisation (i.e.: silica content, porosity, permeability) is very similar to North Sea chalk, but Guerville chalk has never been in contact with oil and generally it crops out of the ground surface. Strength parameters of this rock have been first determined by standard triaxial tests. Three different saturation configurations have been examined: dry, fully oil-saturated and fully water-saturated. As literature clearly state, dry chalk is stronger than oil saturated chalk and the first two are largely stronger than water saturated chalk. Therefore uniaxial strain water injection tests have been performed on oil saturated samples. Results, coupled with previous physical measurements and SEM observation, let us highlight two different contributions to mechanical strength of chalk-: 1) The cohesion due to solid micro-bridges between calcite grains (always present in intact samples); 2) The cohesion due to water capillary menisci (which decreases when the degree of water saturation increases). On these grounds, an elasto-plastic model is proposed is order to explain how contributions are coupled. In this modelling, plastic strain is an hardening parameter while water saturation ratio is a softening one. Applications are developed in order to relate water-driving, stress state and subsidence rate in an oil reservoir configuration. (author)

  3. Crack modelling for the assessment of stiffness loss of reinforced concrete structures under mechanical loading - determination of the permeability of the micro-cracked body; Modelisation de la fissuration pour l'evaluation de la perte d'etancheite des structures en beton arme sous chargements mecaniques

    Energy Technology Data Exchange (ETDEWEB)

    Bongue Boma, M

    2007-12-15

    We propose a model describing the evolution of mechanical and permeability properties of concrete under slow mechanical loading. Calling upon the theory of continua with microstructure, the kinematic of the domain is enriched by a variable characterising size and orientation of the crack field. We call upon configurational forces to deal with crack propagation and we determine the balance equations governing both strain and propagation. The geometry of the microstructure is representative of the porous media: the permeability is obtained from the resolution of Stokes equations in an elementary volume. An example has been treated: we considered simple assumptions (uniform crack field, application of linear fracture mechanics...) and we determined the behaviour of a body under tensile loading. Strain, crack propagation and stiffness loss are completely assessed. Finally the evolution of permeability is plotted: once activated, crack propagation is the main cause of water tightness loss. (author)

  4. Crack modelling for the assessment of stiffness loss of reinforced concrete structures under mechanical loading - determination of the permeability of the micro-cracked body; Modelisation de la fissuration pour l'evaluation de la perte d'etancheite des structures en beton arme sous chargements mecaniques

    Energy Technology Data Exchange (ETDEWEB)

    Bongue Boma, M

    2007-12-15

    We propose a model describing the evolution of mechanical and permeability properties of concrete under slow mechanical loading. Calling upon the theory of continua with microstructure, the kinematic of the domain is enriched by a variable characterising size and orientation of the crack field. We call upon configurational forces to deal with crack propagation and we determine the balance equations governing both strain and propagation. The geometry of the microstructure is representative of the porous media: the permeability is obtained from the resolution of Stokes equations in an elementary volume. An example has been treated: we considered simple assumptions (uniform crack field, application of linear fracture mechanics...) and we determined the behaviour of a body under tensile loading. Strain, crack propagation and stiffness loss are completely assessed. Finally the evolution of permeability is plotted: once activated, crack propagation is the main cause of water tightness loss. (author)

  5. Analysis of the competition between brittle and ductile fracture: application for the mechanical behaviour of C-Mn and theirs welds; Etude de la competition dechirure ductile/rupture fragile: application de la tenue mecanique des tubes en acier C-Mn et de leurs joints soudes

    Energy Technology Data Exchange (ETDEWEB)

    Le Corre, V

    2006-09-15

    This study deals with the fracture behaviour of welded thin structures in the ductile to brittle transition range. It aims to propose a criterion to define the conditions for which the risk of fracture by cleavage does not exist on a cracked structure. The literature review shows that the difficulties of prediction of the fracture behaviour of a structure are related to the dependence of the fracture probability to the mechanical fields at the crack tip. The ductile to brittle transition range thus depends on the studied geometry of the structure. A threshold stress, below which cleavage cannot take place, is defined using fracture tests on notched specimens broken at very low temperature. The finite element numerical simulation of fracture tests onspecimens in the transition range shows a linear relationship between the fracture probability and the volume exceeding the threshold stress, thus showing the relevance of the proposed criterion. Moreover, several relations are established allowing to simplify the identification of the criterion parameters. The criterion is applied to a nuclear structural C-Mn steel, by focusing more particularly on the higher boundary of the transition range. A fracture test on a full-scale pipe is designed, developed, carried out and analysed using its numerical simulation. The results show firstly that, on the structure, the transition range is shifted in temperature, compared to laboratory specimens, due to the low plasticity constraint achieved in thin structures, and secondly that the threshold stress criterion allows to estimate simply this shift. (author)

  6. Modelling of the mechanical behaviour of a material containing spherical cavities under pressure; example of the aging of a metal tritide; Modelisation du comportement mecanique d'un materiau contenant des cavites sous pression; cas du vieillissement d'un tritiure metallique

    Energy Technology Data Exchange (ETDEWEB)

    Chalon, F

    2001-07-01

    The study aims at modeling the mechanical behaviour of a material containing spherical cavities under pressure (bubbles) of nano-metric size. This work deals with research on tritium storage in metals. In this way, metal tritides are obtained. During time, helium is generated by tritium decay. Helium appears as a gas, which forms bubbles in the metal tritide. These bubbles subsequently cause damage within the material. The purpose of this work was therefore the following: (i) to determine the overall elastic moduli as a function of the volume fraction of cavities. thus providing an information about material damage, (ii) to analyze the macroscopic inflation of the material in order to solve storage problems, (iii) to determine the local stress fields for predicting the evolutions of the bubbles and the matrix. With the help of the scale change methods (homogenization) the macroscopic mechanical properties of the material can be determined as a function of its morphology on a microscopic scale. Thus the damage of the material can be estimated by experimental measurements of the global elastic moduli. Homogenization also allows the elastic inflation to be evaluated as well as the effects of cavity clusters and local variations of the elastic moduli. The internal stresses are determined on the microscopic scale (cavity scale). Two analytical methods (Eshelby-Mura and Legendre polynomials) and one numerical approach (Abaqus) are used to obtain more information and a best description of the material. It is shown that bubbles should attain the same size and same pressure and the plastic strain zones are determined. (author)

  7. Contribution to the study of cementitious and clayey materials behaviour in the context of deep geological disposal: transport aspect, durability and thermo-hydro-mechanical behaviour; Contribution a l'etude du comportement des materiaux cimentaires et argileux en vue de leur utilisation dans le contexte du stockage geologique profond: aspect transport, durabilite et comportement thermo-hydro-mecanique

    Energy Technology Data Exchange (ETDEWEB)

    Galle, C.

    2011-07-15

    Deep geological formation disposal is the reference solution in France for the management of medium and high activities radioactive waste. In this context, to demonstrate the feasibility of such a disposal, it is necessary to evaluate the long-term performances and the behaviour of the materials engaged in the elaboration of engineered barrier systems (EBS) and waste package elements. The studies mentioned and synthesized in this HDR thesis focused mainly on the convective transport of gas (under pressure gradient) in cementitious matrices, by coupling microstructure aspect (porosity/pores sizes distribution) and hydric environment (water saturation). Works on physico-chemical durability allowed the description of the chemical degradation of cement-based materials in extreme conditions using ammonium nitrate, to increase the materials damaging processes in order to identify functional margins. In relationship with the interim storage management phase, studies related to the behaviour and characterization of concrete submitted to high temperatures (up to 400 C) were also described. Finally, results concerning the gas (H{sub 2}) overpressure resistance of engineered barriers made of compacted clays were summarized. (author)

  8. Quantum mechanics and molecular dynamics simulations of complexation of alkaline-earth and lanthanide cations by poly-amino-carboxylate ligands; Simulations par mecanique quantique et dynamique moleculaire de la complexation de cations alcalino-terreux et lanthanides par des ligands polyaminocarboxylates

    Energy Technology Data Exchange (ETDEWEB)

    Durand, S

    1999-07-01

    Molecular dynamics (MD) simulations on lanthanide(III) and alkaline-earth(II) complexes with poly-amino-carboxylates (ethylene-diamino-tetra-acetate EDTA{sup 4-}, ethylene-diamino-tri-acetate-acetic acid EDTA(H){sup 3-}, tetra-aza-cyclo-dodecane-tetra-acetate DOTA{sup 4-}, methylene-imidine-acetate MIDA{sup 2-}) are reported. First, a consistent set of Lennard-Jones parameters for La{sup 3+}, Eu{sup 3+} and Lu{sup 3+} cations has been derived from free energy calculations in aqueous solution. Observed differences in hydration free energies, coordination distances and hydration numbers are reproduced. Then, the solution structures of 1:1 complexes of alkaline-earth and/or lanthanide cations with EDTA{sup 4-}, EDTA(H){sup 3-}, DOTA{sup 4-} and 1:2 complexes of lanthanide cations with MIDA{sup 2-} were studied by MD in water. In addition, free energy calculations were performed to study, for each ligand, the relative thermodynamic stabilities of complexes with Ca{sup 2+} vs Sr{sup 2+} and vs Ba{sup 2+} on the one hand, and with La{sup 3+} vs Eu{sup 3+} and vs Lu{sup 3+} on the other hand. Model does not take into account explicitly polarization and charge transfer. However, the results qualitatively agree with experimental complexation data (structure and selectivities). (author)

  9. Modelling of thermo-hydro-mechanical couplings and damage of viscoplastic rocks in the context of radioactive waste storage; Modelisation des couplages thermo-hydro-mecaniques et de l'endommagement des roches viscoplastiques dans le contexte du stockage de dechets radioactifs

    Energy Technology Data Exchange (ETDEWEB)

    Kharkhour, H

    2002-12-01

    Trying to develop a model taking into account the complex rheology of a geologic media characterized by visco-plasticity, damage and thermo-hydro-mechanical couplings is unusual in geotechnics. This is not the case for radioactive waste storage that presents specificities from several viewpoints. Indeed, the scales of time and space concerned by this type of storage are disproportionate to those of civil engineering works or mines. Another specificity of the radioactive waste storage lies in the coupled processes involved. No effect likely to compromise the long-term security of the storage could be ignored. For example this is the case of damage, a phenomenon which does not necessarily lead to a major change of the mechanical behavior of the works but can influence the permeability of the medium in relation with a migration of radionuclides. It can be conceived that this phenomenon finds all its importance in the context of the thermo-hydro-mechanical couplings of a waste storage with high activity. However, the interaction between the damage and the THM coupled processes was the object of very few research subject up to now. This. is even more true for viscoplastic media considered as ductile, and therefore, less prone to cracking than brittle media. It is exactly in this 'original' but difficult context that took place the research presented in this report. This study was dedicated to the analysis of the phenomena and the thermal, hydraulic and mechanical couplings occurring in the near and far field of a high activity radioactive waste storage. Two examples of geological media were considered in this report: the clayey rock of Callovo-Oxfordian, called ' Argilites de l'Est ', target rock of the ANDRA project to carry out a subterranean laboratory for the study of long life radioactive waste storage; and the salt rock of the. subterranean laboratory in the old salt mine of Asse in Germany. (author)

  10. Modeling of the PWR fuel mechanical behaviour and particularly study of the pellet-cladding interaction in a fuel rod; Contribution a la modelisation du comportement mecanique des combustibles REP sous irradiation, avec en particulier le traitement de l`interaction pastille-gaine dans un crayon combustible

    Energy Technology Data Exchange (ETDEWEB)

    Hourdequin, N.

    1995-05-01

    In Pressurized Water Reactor (PWR) power plants, fuel cladding constitutes the first containment barrier against radioactive contamination. Computer codes, developed with the help of a large experimental knowledge, try to predict cladding failures which must be limited in order to maintain a maximal safety level. Until now, fuel rod design calculus with unidimensional codes were adequate to prevent cladding failures in standard PWR`s operating conditions. But now, the need of nuclear power plant availability increases. That leads to more constraining operating condition in which cladding failures are strongly influenced by the fuel rod mechanical behaviour, mainly at high power level. Then, the pellet-cladding interaction (PCI) becomes important, and is characterized by local effects which description expects a multidimensional modelization. This is the aim of the TOUTATIS 2D-3D code, that this thesis contributes to develop. This code allows to predict non-axisymmetric behaviour too, as rod buckling which has been observed in some irradiation experiments and identified with the help of TOUTATIS. By another way, PCI is influenced by under irradiation experiments and identified with the help of TOUTATIS which includes a densification model and a swelling model. The latter can only be used in standard operating conditions. However, the processing structure of this modulus provides the possibility to include any type of model corresponding with other operating conditions. In last, we show the result of these fuel volume variations on the cladding mechanical conditions. (author). 25 refs., 89 figs., 2 tabs., 12 photos., 5 appends.

  11. Cleaning of Livefront Electrical Switchgear Using Carbon Dioxide Pellets at Navy Installations

    Science.gov (United States)

    1998-05-01

    MÄNTENIMIENTO - REPUESTOS ADX 600/- CARATTERISTICHE - CHARACTERISTICS - CARACTERISTIQUES - MERKMALE - CARACTERISTICAS Bicilindrico - Ciclo Diesel 4...Fliehkraftregler - Drehzahlregler - Kurbelgenhäuse aus Aluminium- Druckguss - Zylinder aus Perlitguss - Oelbadluftfilter. Bicilindrico - Ciclo Diesel de

  12. Analyse de l'integration d'un systeme de production photovoltaique ...

    African Journals Online (AJOL)

    29 janv. 2009 ... performances dependent des caracteristiques du site ... a la diminution du cout du generateur photovoltaique et a la gestion ... assurant a travers une action de controle le ... donnees meteorologiques du site de mesure est.

  13. Slow Neutron Spectrometers at the Swedish Reactors; Spectrometres a Neutrons Lents des Reacteurs Suedois; 0421 041f 0415 041a 0422 0420 041e 041c 0415 0422 0420 042b 041c 0415 0414 041b 0415 041d 041d 042b 0425 041d 0415 0419 0422 0420 041e 041d 041e 0412 041d 0410 0428 0412 0415 0414 0421 041a 0418 0425 0420 0415 0410 041a 0422 041e 0420 0410 0425 ; Espectrometros para Neutrones Lentos en los Reactores de Suecia

    Energy Technology Data Exchange (ETDEWEB)

    Dahlborg, U.; Skoeld, K. [AB Atomenergi, Stockholm (Sweden); Larsson, K. -E. [Royal Institute of Technology, Stockholm (Sweden)

    1965-06-15

    is briefly discussed for illustrational purposes. A comparison between the light- and heavy-water moderated reactors for beam tube work shows the distinct advantages of the heavy-water type. (author) [French] Aux centres crees autour des deux, reacteurs de recherche suedois, Rl a Stockholm et R2 a Studsvik, on a maintenant la possibilite d'utiliser quatre spectrometres differents pour les experiences de diffusion inelastique des neutrons. A Stockholm, le reacteur Rl de 600 kW, ralenti a l'eau lourde, est equipe de deux spectrometres mecaniques a neutrons lents qui fonctionnent simultanement, Avec l'un, on utilise toujours un monochromateur a filtre en Be; avec l'autre, on peut employer soit le meme genre de monochromateur, soit un monochromateur a cristal. On a constate que pour les mesures de distribution angulaire, on obtient d'excellents resultats en combinant un monochromateur a cristal et un spectrometre mecanique, meme si l'intensite et le pouvoir de resolution sont relativement faibles. Recemment on a fait l'essai d'un selecteur de vitesse mecanique ayant un pouvoir de separation des longueurs d'onde de 4,2%. Cependant, cet instrument n'est pas encore utilise pour les experiences. Le spectrometre mecanique de Studsvik, avec lequel le reacteur R2 de 30 MW ralenti a l'eau legere est equipe, utilise pour la monochromatisation l'action combinee d'un monochromateur a filtre de Be et d'un hacheur a courbe de transmission etroite. Dans ce spectrometre, de meme que dans celui de Stockholm, le hacheur est place avant l'echantillon, ce qui permet l'enregistrement simultane de donnees pour des angles d'observation differents. Un spectrometre a cristal triaxial est aussi en service pres du reacteur R2. Les auteurs donnent certaines caracteristiques de ces instruments, notamment l'intensite, le pouvoir de resolution, et indiquent dans quelle mesure ils conviennent pour certaines operations. Ainsi, il ressort des donnees numeriques mentionnees qu'une amelioration assez

  14. Study of the argillaceous fraction of sedimentary sequences of Meuse and Gard. Reconstitution of the diagenetic history and of the physico-chemical characteristics of the targets. Mineralogical, geochemical and isotopic aspects; Etude de la fraction argileuse de sequences sedimentaires de la Meuse et du Gard. Reconstitution de l'histoire diagenetique et des caracteristiques physico-chimiques des cibles. Aspects mineralogiques, geochimiques et isotopiques

    Energy Technology Data Exchange (ETDEWEB)

    Rousset, D

    2002-01-01

    Very low permeable argillaceous rocks like Callovo-Oxfordian clay-stones or Vraconian siltstones were chosen to host a research laboratory built to determine the physico-chemical properties of the host formations for a potential underground disposal of radioactive waste. Knowledge and understanding of post-sedimentary modifications are of prime importance for definition of these properties; evaluation and quantification of the post-sedimentary changes represent the aim of this study, focused specifically on the clay material of the sequences. Samples were taken from two drillings (HTM102 and MAR501). In the HTM102 core samples, illite and mixed-layers illite/smectite are the dominant clay components of most clay fractions. Systematic SEM and TEM observations and isotopic K-Ar and Rb-Sr analyses pointed to diagenetic neo-formations of carbonates (calcite, dolomite) and clays. For instance, veils and laths of authigenic clay particles around old detrital ones can distinctly be observed. The epoch, duration and extent of the diagenetic activity(ies) are difficult to evaluate because of an overall detrital contribution even in the finest granulometric fractions. However; analysis of a bentonite layer in the sequence provides a diagenetic reference for the authigenic clay material. Correlation between relative sea level and authigenesis of smectite-rich mineral has been outlined. Chemistry of diagenetic fluids also seems to be reliable with sea level variations. These observations argue in favour of diagenetic activities limited in restricted rock volumes. The case study of MAR501 is close to the HTM102 one: smectite-rich illite/smectite mixed-layers represent the major component of the clay fraction and K-Ar values argue ire the sense of a mixing between detrital and younger clay populations. Diagenetic glauconites in the sequence yield are age close to 93,7 {+-}0,3 Ma for Vraconian level, in agreement with stratigraphical data. The case study of a clay-filled fault within the sequence favors a confined-sequence behaviour: Indeed, no migrations of elements and especially of REE took place during fluid flows, the clay minerals preserving their geochemical properties. All the results favor reliable confinement properties of the low-permeable argillaceous sequences. (author)

  15. Study of the argillaceous fraction of sedimentary sequences of Meuse and Gard. Reconstitution of the diagenetic history and of the physico-chemical characteristics of the targets. Mineralogical, geochemical and isotopic aspects; Etude de la fraction argileuse de sequences sedimentaires de la Meuse et du Gard. Reconstitution de l'histoire diagenetique et des caracteristiques physico-chimiques des cibles. Aspects mineralogiques, geochimiques et isotopiques

    Energy Technology Data Exchange (ETDEWEB)

    Rousset, D

    2002-01-01

    Very low permeable argillaceous rocks like Callovo-Oxfordian clay-stones or Vraconian siltstones were chosen to host a research laboratory built to determine the physico-chemical properties of the host formations for a potential underground disposal of radioactive waste. Knowledge and understanding of post-sedimentary modifications are of prime importance for definition of these properties; evaluation and quantification of the post-sedimentary changes represent the aim of this study, focused specifically on the clay material of the sequences. Samples were taken from two drillings (HTM102 and MAR501). In the HTM102 core samples, illite and mixed-layers illite/smectite are the dominant clay components of most clay fractions. Systematic SEM and TEM observations and isotopic K-Ar and Rb-Sr analyses pointed to diagenetic neo-formations of carbonates (calcite, dolomite) and clays. For instance, veils and laths of authigenic clay particles around old detrital ones can distinctly be observed. The epoch, duration and extent of the diagenetic activity(ies) are difficult to evaluate because of an overall detrital contribution even in the finest granulometric fractions. However; analysis of a bentonite layer in the sequence provides a diagenetic reference for the authigenic clay material. Correlation between relative sea level and authigenesis of smectite-rich mineral has been outlined. Chemistry of diagenetic fluids also seems to be reliable with sea level variations. These observations argue in favour of diagenetic activities limited in restricted rock volumes. The case study of MAR501 is close to the HTM102 one: smectite-rich illite/smectite mixed-layers represent the major component of the clay fraction and K-Ar values argue ire the sense of a mixing between detrital and younger clay populations. Diagenetic glauconites in the sequence yield are age close to 93,7 {+-}0,3 Ma for Vraconian level, in agreement with stratigraphical data. The case study of a clay-filled fault within the sequence favors a confined-sequence behaviour: Indeed, no migrations of elements and especially of REE took place during fluid flows, the clay minerals preserving their geochemical properties. All the results favor reliable confinement properties of the low-permeable argillaceous sequences. (author)

  16. Dosimetric implications of inter- and intrafractional prostate positioning errors during tomotherapy. Comparison of gold marker-based registrations with native MVCT

    Energy Technology Data Exchange (ETDEWEB)

    Wust, Peter; Joswig, Marc; Graf, Reinhold; Boehmer, Dirk; Beck, Marcus; Barelkowski, Thomasz; Budach, Volker; Ghadjar, Pirus [Charite Universitaetsmedizin Berlin, Department of Radiation Oncology and Radiotherapy, Berlin (Germany)

    2017-09-15

    For high-dose radiation therapy (RT) of prostate cancer, image-guided (IGRT) and intensity-modulated RT (IMRT) approaches are standard. Less is known regarding comparisons of different IGRT techniques and the resulting residual errors, as well as regarding their influences on dose distributions. A total of 58 patients who received tomotherapy-based RT up to 84 Gy for high-risk prostate cancer underwent IGRT based either on daily megavoltage CT (MVCT) alone (n = 43) or the additional use of gold markers (n = 15) under routine conditions. Planned Adaptive (Accuray Inc., Madison, WI, USA) software was used for elaborated offline analysis to quantify residual interfractional prostate positioning errors, along with systematic and random errors and the resulting safety margins after both IGRT approaches. Dosimetric parameters for clinical target volume (CTV) coverage and exposition of organs at risk (OAR) were also analyzed and compared. Interfractional as well as intrafractional displacements were determined. Particularly in the vertical direction, residual interfractional positioning errors were reduced using the gold marker-based approach, but dosimetric differences were moderate and the clinical relevance relatively small. Intrafractional prostate motion proved to be quite high, with displacements of 1-3 mm; however, these did not result in additional dosimetric impairments. Residual interfractional positioning errors were reduced using gold marker-based IGRT; however, this resulted in only slightly different final dose distributions. Therefore, daily MVCT-based IGRT without markers might be a valid alternative. (orig.) [German] Bei der hochdosierten Bestrahlung des Prostatakarzinoms sind die bildgesteuerte (IGRT) und die intensitaetsmodulierte Bestrahlung (IMRT) Standard. Offene Fragen gibt es beim Vergleich von IGRT-Techniken im Hinblick auf residuelle Fehler und Beeinflussungen der Dosisverteilung. Bei 58 Patienten, deren Hochrisiko-Prostatakarzinom am

  17. Fe Al40, a new canning material for reactors using refractory fuels; Le Fe Al40, un nouveau materiau de gainage pour les reacteurs a combustibles refractaires

    Energy Technology Data Exchange (ETDEWEB)

    Sainfort, G; Cabane, G; Salesse, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    18-10 niobium - stabilized stainless steel, in water, either de oxygenated or saturated with oxygen at 25 C, the weight gain is one hundred time smaller than that of mild steel, after a 3 month test, in water vapour at 500 C, also after 3 months, only the growth of impervious and very adherent oxide skins is observed, in sodium up to 1000 h at 700 C, the behaviour is at least as good as that of stainless steel. No diffusion reaction has been detected either with uranium dioxide up to 800 C, or with uranium carbide up to 700 C. Extension specimens and thin walled cans are subjected to high flux irradiations between 20 and 700 C; preliminary results will be given. (authors) [French] Le Fe Al40, grace a sa haute teneur en aluminium, presente de grands avantages sur les aciers inoxydables, pour les applications nucleaires; en particulier, sa section efficace est moitie de celle de l'acier a 18 p.100 Cr et 10 p.100 Ni, et sa compatibilite avec les elements combustibles et avec les fluides caloporteurs est exceptionnellement bonne. Les alliages ferreux, contenant plus de 16 p.100 en poids d'aluminium, sont reputes fragiles en raison de leur structure ordonnee. En fait, la plus grande partie de la fragilite de ces alliages est due a la presence de precipites intergranulaires. L'emploi de fer et d'aluminium purs, ainsi que des additions destinees a pieger les traces d'impuretes residuelles, permet d'obtenir, par coulee sous vide, un alliage tres propre dont la fragilite a chaud est suffisamment reduite pour permettre une transformation. avec un excellent rendement. Les etudes de fonderie et de transformation, qui ont defini la composition de l'alliage et les meilleures conditions industrielles de preparation, seront decrites. Les proprietes mecaniques des produits files ou lamines sont conditionnees par la structure ferritique ordonnee des alliages ainsi prepares: allongement par traction a temperature ambiante compris entre 8 et 11 p.100, augmentation progressive de l

  18. Industrial Ultrasonic Inspection of Stainless-Steel Claddings for the EL4 Reactor; Controle Industriel par Ultrasons des Gaines en Acier Inoxydable du Reacteur EL4; Promyshlennyj kontrol' obolochechnykh trub iz nerzhaveyushchej stali reaktora dlya EL4 s pomoshch'yu ul'trazvukovogo metoda; Metodos Ultrasonicos para Control Industrial de las Vainas de Acero Inoxidable del Reactor EL4

    Energy Technology Data Exchange (ETDEWEB)

    Prot, A. C.; Foulquoer, H. E.; Peyrot, J. P. [Centre d' Etudes Nucleaires de Saclay (France)

    1965-09-15

    essentiel de rentabilite du reacteur. Il s'avere que le choix de la methode a utiliser et a mettre au point est delicat; le memoire en donne les elements essentiels. Ce choix etant fait, apres mise au point en laboratoire, deux nouveaux problemes se posent: - la transposition dans le domaine industriel; - la necessite de tenir compte de la qualite permise, a un instant determine, par les procedes de fabrication, en relation avec les normes de reception definies de maniere plus ou moins arbitraire. Ceci se traduit en fait par la necessite d'une etude statistique sur des lots de tubes de diverses provenances, et leur classement par rapport a des seuils plus ou moins severes. On verra que le nombre de tubes a controler est tres superieur a celui prevu initialement. Cela conduit a l'etude d'une machine de controle automatique, capable de satisfaire a la fois les exigences de cadence et celles propres au type de controle choisi: ces dernieres sont generalement d'ordre mecanique et necessitent une construction particulierement soignee. L'ensemble de ces considerations a conduit a concevoir une machine dont la cadence peut des maintenant couvrir sans difficulte les besoins d'une chaihe de fabrication d'elements combustibles. Les possibilites de cette machine sont etroitement liees aux caracteristiques du materiel de controle choisi, en particulier aux performances de l'electronique des appareils de controle par ultrasons et a celles des traducteurs utilises. Il resulte d'ailleurs de cette etude que le materiel standard ne repond que tres imparfaitement au probleme et que l'on doit envisager des maintenant un appareillage particulier pour ce type de controle. (author) [Spanish] Las mayores exigencias a que se someten los reactores obligan a utilizar materiales elaborados y controlados con sumo cuidado. Un aspecto de tal control se refiere a la calidad de las vainas empleadas, cuyas propiedades mecanicas ejercen una influencia decisiva sobre la rentabilidad del reactor. La eleccion

  19. Problems related with the power regulation of reactors by physico-chemical methods, and the behaviour of water and heavy water in nuclear reactors; Comportement de l'eau et de l'eau lourde dans les reacteurs nucleaires et problemes de la regulation de puissance par voie physico-chimique

    Energy Technology Data Exchange (ETDEWEB)

    Dolle, L; Conan, D; Dirian, G [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    . Comportement de l'eau lourde dans les reacteurs en exploitation. Pollution isotopique de l'eau lourde: Sa vitesse est liee au type de reacteur et a certains incidents caracteristiques. L'utilisation d'une colonne de reconcentration est un moyen efficace pour maintenir le titre de l'eau lourde dans un reacteur dont la pollution isotopique lente ne peut etre exclue. Detection des fuites d'eau lourde: Elle permet de mesurer les taux instantanes de fuites faibles, de localiser la fuite, et de controler la contamination atmospherique dans l'enceinte du reacteur. On procede par analyse isotopique du deuterium ou par dosage du tritium sur des echantillons d'eau de condensation. Pollution chimique et epuration de l'eau lourde: La pollution chimique de l'eau lourde constitue un des problemes les plus complexes de la chimie des reacteurs. La corrosion des materiaux constituant le coeur et le circuit d'eau lourde varie dans de larges limites avec l'etat de purete de l'eau lourde, les performances des circuits d'epuration et des mesures directes permettent d'en apprecier l'importance. Les connaissances acquises permettent de degager des normes de purete dont l'observation est susceptible de garantir un fonctionnement satisfaisant du reacteur. 4) Decomposition radiolytique de l'eau lourde: Une meilleure connaissance de son allure quantitative dans les reacteurs est necessaire pour prevoir les degagements de gaz tonnant dans les reacteurs de puissance. Le taux de radiolyse evolue avec la purete chimique de l'eau et la puissance instantanee du reacteur. L'experience des reacteurs a eau lourde du CE.A. et l'etude systematique de la decomposition radiolytique de l'eau dans le coeur des piles piscines sont exposees Mise en oeuvre du controle de la reactivite par voie physico-chimique. Controle de la reactivite par empoisonnement homogene du moderateur: Une comparaison de l'evolution de l'empoisonnement Xenon avec l'antireactivite residuelle du poison en solution pendant sa consommation

  20. Notification of the French Energy Regulator the 5 june 2001 on the order fixing the purchase conditions of the electricity produced by installations using the wind energy; Avis de la commission de regulation de l'electricite en date du 5 juin 2001 sur l'arrete fixant les conditions d'achat de l'electricite produite par les installations utilisant l'energie mecanique du vent

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-06-01

    This document presents the economic analysis realized by the CRE, French Energy Regulator, to give its opinion on the order concerning the purchase conditions of the electricity produced by wind energy. An operating costs comparison with other energies forms shows that the proposed tariff will lead to a significant increase of the electric power. In consequence, the CRE is opposed to this order. (A.L.B.)

  1. Notes on the development of the gibbs potential; Sur le developpement du potentiel de gibbs

    Energy Technology Data Exchange (ETDEWEB)

    Bloch, C; Dominicis, C de [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1959-07-01

    A short account is given of some recent work on the perturbation expansion of the Gibbs potential of quantum statistical mechanics. (author) [French] Expose en resume de quelques travaux sur le developpement dans la theorie des perturbations du potentiel de Gibbs de la Mecanique Statistique. (auteur)

  2. Naines blanches : Les diamants sont éternels

    Science.gov (United States)

    Bonnet-Bidaud, J. M.

    1997-08-01

    Ces etoiles minuscules, composantes essentielles de la Galaxie, sont responsables de phenomenes spectaculaires, comme les novae ou certaines supernovae. Mais les naines blanches se sont aussi revelees un fantastique outil pour la physique du XXe siecle, fournissant des confirmations eclatantes de deux grandes theories: la relativite generale et la mecanique quantique.

  3. Recent developments in the field of refractory fuels; Developpements recents dans le domaine des combustibles refractaires

    Energy Technology Data Exchange (ETDEWEB)

    Accary, A; Delmas, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    or arc fusion). This latter method is based on fusion by electronic bombardment associated with the continuous casting. (authors) [French] L'effort des recentes annees au Commissariat a l'Energie Atomique dans le domaine des combustibles ceramiques a surtout porte sur le bi-oxyde d'uranium et les alliages uranium-carbone. Le bi-oxyde d'uranium est etudie dans l'optique de son utilisation comme combustible de la premiere charge d'EL 4, dans laquelle on impose au point le plus charge une conductibilite thermique integree de 29 W/cm pour une temperature de surface de 750 C environ. On s'est specialement preoccupe de mettre en place un procede de preparation d'une poudre de bi-oxyde de bonnes caracteristiques et le frittage industriel de cette poudre, et d'evaluer les principales proprietes des corps obtenus en relation avec les conditions des corps obtenus en relation avec les conditions prevues de leur utilisation: - aspect de micro-structure et distribution des pores, - comportement mecanique et thermique en geometrie cylindrique, - controle de l'oxygene excedentaire dans les produits industriels, - compatibilite aux hautes temperatures avec les oxydes utilisables comme isolants thermiques, - comportement des produits de fission gazeux a haute temperature apres irradiation ou au cours de l'irradiation. Dans le cas des carbures d'uranium, notre but a ete de determiner les conditions de fabrication industrielle d'un combustible satisfaisant de composition voisine de UC. Ceci nous a conduits a entreprendre un certain nombre d'etudes fondamentales Sur le domaine d'existence de UC non stoechiometrique, - l'influence, sur les proprietes de UC, des elements O et N dissous dans ce materiau, - la compatibilite des alliages uranium-carbone avec differents materiaux de gaine metalliques ou ceramiques, - la corrosion des alliages uranium-carbone par H{sub 2}O et CO{sub 2}, - les methodes de preparation d'echantillons de haute purete, - les dispositifs d'irradiation en pile

  4. Some of the properties of plutonium and the aluminium-plutonium alloy; Quelques proprietes du plutonium et de l'alliage aluminium-plutonium

    Energy Technology Data Exchange (ETDEWEB)

    Abramson, R; Boucher, R; Fabre, R; Monti, H [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1959-07-01

    physiques du plutonium. 1) Etude de l'allotropie du plutonium. a) Analyse thermique. On decrit brievement l'appareillage utilise et la technique de mesure. Les temperatures des points de transition et les chaleurs de transformation correspondantes ont ete determinees. Enfin, les resultats de l'etude particuliere de quelques points de transition sont exposes. b) Dilatometrie. L'analyse dilatometrique des changements de phase du plutonium a ete poursuivie a l'aide du dilatometre Chevenard a enregistrement photographique. On a fait varier les conditions de l'essai (vitesse de chauffe et de refroidissement, paliers isothermes, etc...) de maniere a preciser les caracteristiques de chaque transition notamment de la transition {delta} {yields} {gamma} au refroidissement. 2) Micrographie du plutonium. La preparation correcte des echantillons metallographiques exige une duree de polissage electrolytique tres courte, ce qui implique un polissage mecanique d'excellente qualite. On indique de nouveaux reactifs d'attaque qui revelent la structure du metal avec une grande nettete. 2- Etude des alliages aluminium-plutonium. Etude comparee des alliages Al-Pu et AI-U riches en aluminium. a) Analyse thermique. Les temperatures du liquidus et de fusion de l'eutectique Al-XAl{sub 4} ont ete precisees. La mesure des chaleurs de fusion a permis de determiner la composition exacte de l'alliage eutectique. b) Traitement thermique. La cinetique de coalescence de l'eutectique a ete etudiee par voie micrographique et en suivant l'evolution de la durete. Les resultats obtenus indiquent que le phenomene est plus rapide dans les alliages Al-Pu que dans les alliages AI-U. c) Etude micrographique de la transition XAI{sub 3} {yields} XAl{sub 4}. La reaction peritectique XAI{sub 3} + Iiq. {yields} XAI{sub 4} a ete supprimee par trempe. La transformation de la phase XAI{sub 3} a l'etat solide a ete etudiee ainsi que l'effet de faibles additions de silicium sur la cinetique de cette reaction. (auteur)

  5. Instrumentation for Sodium Circuits; Instrumentation des Circuits de Sodium

    Energy Technology Data Exchange (ETDEWEB)

    Cambillard, E. [CEA, Centre d' Etudes Nucleaires de Fontenay-aux-Roses (France); Lions, N. [CEA, Centre d' Etudes Nucleaires de Cadarache (France)

    1967-06-15

    RAPSODIE. A description is given of the modifications carried out in connection with the mechanical zero adjustment and the measurement chain. (author) [French] Les instruments de mesure qui ont ete principalement etudies et experimentes au CEA pour les reacteurs ''a sodium comportent des debitmietres electromagnetiques, des indicateurs de niveau et des manometres differentiels. Les auteurs donnent les caracteristiques principales des debitmietres du reacteur RAPSODIE, qui sont a aimant permanent ou a electro -aimant (sur les circuits primaires). Ils decrivent les methodes d'etalonnage utilisees qui font appel a des diaphragmes ou des Venturis comme debitmietres etalons et indiquent les resultats de mesure obtenus pour des debits de sodium maximaux de 400 m{sup 3}/h. Trois types d'indicateurs continus de niveau ont ete etudies: Indicateur a resistance. Les auteurs decrivent deux variantes equipant les circuits d'essai de RAPSODIE de 1 et 10 MW. L'une comporte une resistance de compensation disposee sur toute la hauteur de l'element de mesure (les indicateurs continus du reacteur RAPSODIE sont actuellement de ce type). L'autre possede un dispositif permettant le chauffage d e l ''element de mesure en vue d {sup e}mpecher la formation- eventuelle de depots conducteurs (les essais en sodium de prototypes sont termines). Indicateur a induction Il comprend deux bobines couplees et un dispositif permettant une compensation des effets de temperature. Les auteurs decrivent le prototype qui a ete construit et indiquent les resultats obtenus au cours des essais en sodium. Indicateur ultra-sons. Il est caracterise par l'utilisation d'un transmetteur place en haut et a l'exterieur de la cuve de sodium, et d'un guide d'ondes vertical dont l'extremite inferieure plongeant dans le metal liquide possede un systeme reflechissant qui renvoie le faisceau ultra-sonore vera la surface. Des reperes fixes permettent un etalonnage permanent; l'ensemble de l'appareil est entierement soude. Cet

  6. The Scottish Research Reactor Centre and its Facilities for the Production and Exploitation of Short-Lived Radioisotopes; Le Réacteur de Recherche Ecossais et ses Installations pour la Production et l'Exploitation des Radioisotopes a Courte Periode; ШОТЛАНДСКИЙ ИССЛЕДОВАТЕЛЬСКИЙ РЕАКТОРНЫЙ ЦЕНТР И ЕГО ТЕХНИЧЕСКИЕ СРЕДСТВА ДЛЯ ПРОИЗВОДСТВА И ИСПОЛЬЗОВАНИЯ КОРОТКОЯИВУШХ РАДИОИЗОТОПОВ; El Centro del Reactor de Investigacion de Escocia y sus Instalaciones para la Produccion y Empleo de Radioisotopos de Periodo Corto

    Energy Technology Data Exchange (ETDEWEB)

    Ward, A. [The Royal College of Science and Technology, Glasgow, Scotland (United Kingdom)

    1963-03-15

    de cSte, qui penetre jusqu'au centre du coeur. De nombreuses gouttieres horizontales traversent la colonne thermique, la gouttiere centrale penetrant jusqu'a 2,5 cm d'un reservoir de combustible. Le reacteur est dote de toute une serie de petits laboratoires adjacents: installations de manutention et de preparation de sources de haute activite, vestiaires, ateliers d'electricite et de mecanique, chambres noires, laboratoires pour activites de l'order du microcurie, salle pour animaux, laboratoires de biologie et de chimie, salle de comptage a faible bruit de fond'amphitheatre et bibliotheque. On pense que les recherches s'etendront a de nombreuses disciplines scientifiques et technologiques; une grande partie du travail portera sur les radioisotopes a courte periode; l'auteur decrit quelques projects caracteristiques. (author) [Spanish] El centro del reactor de investigacion de Escocia se encuentra en construccion, calculandose que entrara en servicio en el verano de 1963. El reactor de tipo tanque tiene una potencia de 100 kW, es refrigerado por agua y moderado por agua y grafito; el combustible es uranio enriquecido en el isotopo sssu. Las instalaciones experimentales consisten en una gran columna termica, con tanque de agua blindado de grandes dimensiones y una instalacion de produccion de radioisotopos con tuberias de transporte neumatico. El cuerpo central es atravesado por tres tubos, la columna termica, por uno; ademas, existen varios pequenos dispositivos centrales de acceso vertical y otro dispositivo de acceso de seccion cuadrada , de 6 pulgadas, que penetra verticalmente hasta el centro del cuerpo del reactor. Muchos otros dispositivos de acceso horizontal atraviesan la columna termica, y el del centro del cuerpo penetra hasta 1 pulgada de los tanques de combustible. El centro comprendera un gran numero de locales auxiliares en los que se instalaran dispositivos para manejar y preparar fuentes de alta actividad, vestuarios, talleres electricos y mecanicos

  7. Regularities in the Changes of Absorber Material Properties as a Function of Absorber Concentration; Regularite des Variations des Proprietes des Substances Absorbantes en Fonction de la Concentration de l'Absorbant; Zakonomernosti izmeneniya svojstv poglashchayushchikh materialov v zavisimosti ot kontsentratsii poglotitelya; Leyes de Variacion de las Propiedades de los Materiales Absorbentes en Funcion de la Concentracion del Absorbente

    Energy Technology Data Exchange (ETDEWEB)

    Portnoj, K. I.

    1964-06-15

    The paper presents regularities of the change in mechanical and heat-physical properties as well as in absorption capability as a function of absorber concentration for thermal and intermediate reactors. The thermal conductivity and the thermal expansion coefficient of absorber alloys containing boron and rare-earth element oxides is reduced with an increase of absorber concentration. Alloys with rare-earth element oxides have a linear law of the thermal expansion coefficient change, while for boron containing alloys this additive law of changes of properties is disturbed. This is caused by formation under high temperatures of boride phases with various crystal lattices. It is shown in the paper that absorption capability, being a function of absorber concentration, is changed along a curve with saturation and depends on the neutron spectrum. A hypothesis of the author on formation of absorption capability maximum under mutual alloying of absorbers is set forth. The hypothesis has got a wide experimental confirmation on a large number of metal and non-metal absorber system compositions in thermal and intermediate reactors. (author) [French] Le memoire expose la regularite des variations des proprietes mecaniques et thermiques ainsi que du pouvoir absorbant en fonction de la concentration de l'absorbant dans les reacteurs a neutrons thermiques et intermediaires. La conductibilite thermique et le coefficient de dilatation thermique des combinaisons absorbantes contenant du bore et des oxydes de terres rares diminuent a mesure qu'augmente la concentration de l'absorbant. Pour les combinaisons qui contiennent des oxydes de terres rares, la variation du coefficient de dilatation thermique est regie par une loi lineaire. Dans le cas des combinaisons contenant du bore, cette loi de variation des proprietes n'est pas rigoureusement applicable, du fait de la formation, a haute temperature, de phases 'borare' avec divers reseaux cristallins. Le memoire demontre que le

  8. Heavy water moderated gas-cooled reactors; Filiere eau lourde - gaz

    Energy Technology Data Exchange (ETDEWEB)

    Bailly du Bois, B; Bernard, J L; Naudet, R; Roche, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    long terme de reacteurs rapides, s'est engagee egalement dans le developpement des reacteurs a eau lourde refroidis par gaz, qui semblent presenter les meilleures perspectives pour le moyen terme. L'economie de ces reacteurs, comme dans le cas du graphite, repose sur l'utilisation d'uranium naturel ou extremement peu enrichi. L'eau lourde permet d'en tirer le maximum d'avantages, tout en donnant lieu grace a ses performances plus poussees a des perspectives de developpement tres interessantes. Une centrale prototype EL 4 (70 MWe) est actuellement en construction: elle est decrite en detail dans un autre memoire. La presente communication fait le point du programme consacre en France au developpement de cette filiere. On indique d'abord quelles sont les raisons qui ont conduit a choisir ce type de reacteur: on montre l'Interet de la filiere, en soulignant ses atouts et ses difficultes. Passant en revue les principaux problemes technologiques et les travaux de developpement qui leur sont consacres, on analyse ensuite les resultats deja acquis et les points restant a confirmer. EL 4 est la premiere grande realisation: sa construction constitue une etape importante, aussi bien du point de vue demonstration de performances que possibilites d'experimentation et d'epreuve. Mais deja se pose le probleme de la conception d'une centrale de grande puissance unitaire. On a etudie a la fois l'adaptation ou l'amelioration des solutions mecaniques mises en oeuvre dans EL 4 et des variantes dont quelques-unes reposent sur des conceptions assez differentes. On indique ensuite quelles sont les caracteristiques envisagees pour une grande centrale dans l'etat actuel de la technique, compte tenu des etudes d'optimisation en cours. Des possibilites d'amelioration techniques existent d'ailleurs notamment en ce qui concerne les materiaux, ce qui pourrait conduire a des performances encore plus interessantes. Quelques perspectives a plus long terme sont evoquees. Finalement on aborde les

  9. Syndrome de Gougerot-Sjögren primitif du sujet âgé ...

    African Journals Online (AJOL)

    Les objectifs de notre etude est d'etudier les caracteristiques cliniques et immunologiques du syndrome de Gougerot Sjogren primitif (SGSp) du sujet age et les comparer a une population temoin plus jeune. Nous avons analyse retrospectivement les dossiers de 60 patients atteints de SGSp consecutifs, suivis au service de ...

  10. Security report on Siloe - the descriptive part. (1963); Rapport de surete de Siloe - partie descriptive (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Ageron, P; Chatoux, J; Denielou, G; Jacquemain, M; Mitault, G; Robien, E de; Rossillon, F [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1963-07-01

    This report is a full description of the site, the reactor, the building and the experimental facilities. It gives the nuclear, thermodynamic and hydrodynamic characteristics of the core. (authors) [French] Ce rapport decrit completement le site, le reacteur, les batiments et les installations experimentales. Il donne les caracteristiques nucleaires, thermodynamiques et hydrodynamiques du coeur. (auteurs)

  11. Contribution to the study of the structure of silver krypton solid solutions; Contribution a l'etude de la structure des solutions solides argent-krypton

    Energy Technology Data Exchange (ETDEWEB)

    Levy, V; Tullairet, J; Delaplace, J; Antolin-Baudier, J; Adda, Y [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    The silver-krypton solid solutions formed by electrical discharge have been studied by X-rays, electrical resistivity and electronic transmission microscopy. The crystalline parameter and residual resistivity measurements have shown that the krypton atom behaves very differently to those of other elements of the periodic classification when dissolved in silver. The recovery of the crystalline parameter and of the electrical resistivity has been studied as a function of temperature. (authors) [French] Les solutions solides argent, krypton, realisees par decharges electrique ont ete etudiees par Rayons X, resistivite electrique et microscopie electronique en transmission. Les mesures de parametre cristallin et de resistivite residuelle ont montre que le comportement de l'atome de krypton est tres different de celui des autres elements de la classification periodique en solution dans l'argent. La restauration du parametre cristallin et de la resistivite electrique en fonction de la temperature a ete etudiee. (auteurs)

  12. The determination by irradiation with a pulsed neutron generator and delayed neutron counting of the amount of fissile material present in a sample; Determination de la quantite de matiere fissile presente dans un echantillon par irradiation au moyen d'une source pulsee de neutrons et comptage des neutrons retardes

    Energy Technology Data Exchange (ETDEWEB)

    Beliard, L; Janot, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-07-01

    A preliminary study was conducted to determine the amount of fissile material present in a sample. The method used consisted in irradiating the sample by means of a pulsed neutron generator and delayed neutron counting. Results show the validity of this method provided some experimental precautions are taken. Checking on the residual proportion of fissile material in leached hulls seems possible. (authors) [French] Ce rapport rend compte d'une etude preliminaire effectuee en vue de determiner la quantite de matiere fissile presente dans un echantillon. La methode utilisee consiste a irradier l'echantillon considere au moyen d'une source puisee de neutrons et a compter les neutrons retardes produits. Les resultats obtenus permettent de conclure a la validite de la methode moyennant certaines precautions. Un controle de la teneur residuelle en matiere fissile des gaines apres traitement semble possible. (auteurs)

  13. Some considerations of the energy spectrum of odd-odd deformed nuclei; Quelqes considerations sur le spectre d'energie des noyaux impair-impair deformes

    Energy Technology Data Exchange (ETDEWEB)

    Alceanu-G, Pinho de; Picard, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-07-01

    The odd-odd deformed nuclei are described as a rotator plus two odd nucleons moving in orbitals {omega}{sub p} and {omega}{sub n} of the deformed potential. We investigate the energies and wave functions of the various states of the ({omega}{sub p}, {omega}{sub n}) configurations by calculating and numerically diagonalizing the Hamiltonian matrix (with R.P.C. and residual interactions). The Gallagher-Mosskowski coupling rules ana the abnormal K equals 0 rotational bands are discussed. (authors) [French] Les noyaux impair-impairs deformes sont decrits comme un rotateur plus deux nucleons non apparies dans les orbites {omega}{sub p} et {omega}{sub n} du potentiel deforme. Nous etudions le spectre d'energie et les fonctions d'onde des configurations ({omega}{sub p}, {omega}{sub n}) en tenant compte de l'interaction particule-rotation et de la force residuelle entre les deux nucleons celibataires.

  14. Giant resonance and dipolar states of light nuclei; La resonance geante et les etats dipolaires des noyaux legers

    Energy Technology Data Exchange (ETDEWEB)

    Miller, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-07-01

    Cross-section for ({gamma},n) reactions on C{sup 12},, O{sup 10}, Mg{sup 24} and Ca{sup 40} have been measured using 'monochromatic' gamma rays of variable energy obtained from the annihilation in flight of fast positrons. We compare the observed structure with the shell model of nucleus, including residual interaction between nucleons by 'hole particle' techniques. (author) [French] Les photons 'monochromatiques', d'energie variable, produits par l'annihilation en vol de positons, sont utilises pour mesurer la section efficace ({gamma},n) de {sup 12}C, {sup 16}O, {sup 21}Mg et {sup 40}Ca. La structure observee est comparee aux previsions theoriques du modele a particules independantes, tenant compte de l'interaction residuelle entre nucleons par la methode 'trou-particule'. (auteur)

  15. L'espace articulaire de la Robotique Industrielle est un espace vectorielIndustrial Robotics joint space is a vector space

    Science.gov (United States)

    Tondu, Bertrand

    2003-05-01

    The mathematical modelling of industrial robots is based on the vectorial nature of the n-dimensional joint space of the robot, defined as a kinematic chain with n degrees of freedom. However, in our opinion, the vectorial nature of the joint space has been insufficiently discussed in the literature. We establish the vectorial nature of the joint space of an industrial robot from the fundamental studies of B. Roth on screws. To cite this article: B. Tondu, C. R. Mecanique 331 (2003).

  16. Evaluation of Motor Gasoline Stability

    Science.gov (United States)

    1990-12-01

    CAMPINNE AIR POLLUTION CONTROL I LABORATOIRE MECANIQUE TRANSPORT 2565 PLYMOUTH ROAD AVENUE DE LA RENAISSANCE, 3D ANN ARBOR MI 48105 B-1040 BRUSSELS 5...CUARTEL GENERAL DEL EJERCITO ATTN: MR K LAURINSEN ATTN: MAJ M ENGO NOGUES GADHOLTVEJ 11 DIVISION DE LOGISTICA (DIAM/LABCAMVE) DK-9900 FREDERIKSHAVN...Gum for Typical Civilian Gasolines Transported by CEPS and F-46 Gasolines Stored by CEPS ...................................... 47 B. Potential Gum

  17. Detection of a bad mechanical adjustment of a stator through a CEPSTRALE analysis method

    International Nuclear Information System (INIS)

    Le Reverend, D.

    1985-01-01

    After the failure of the stator of the CRUAS 2 nuclear power plant, a full check up was necessary before restarting the engine. In spite of examinations and repairs, a defect could remain. Thereby, an on line surveillance system is usefull, especially during the first months after start up. The ''Mecanique appliquee'' division developed a device for the surveillance of the mechanical integrity of the stator. This equipment is based on the analysis of the vibration [fr

  18. Micromechanisms of Crack Growth in Ceramics and Glasses in Corrosive Environments.

    Science.gov (United States)

    1980-05-01

    Resistance Mecanique du Verre et les Moyens de l’Amelioree, Union Scientifique Continentale du Verre , Charleroix, Belgium, (1962). 8. B. A. Proctor, I...exhibit similar types of delayed failure curves. Failure occurs most rapidly at high loads. Below a critical value of the load known as the stress...fracture for the three types of materials differ greatly. Polymers and metals have plastic zones at their crack tips, so that stress corrosion

  19. SYSTEME MULTISENSEUR DE PERCEPTION 3D POUR LE ROBOT MOBILE HILARE

    OpenAIRE

    Ferrer , Michel

    1982-01-01

    L'ETUDE PRESENTEE S'INSERE DANS LE VASTE DOMAINE DE LA VISION ARTIFICIELLE. ELLE CONCERNE PLUS PARTICULIEREMENT L'INTEGRATION DU SYSTEME DE PERCEPTION TROIS DIMENSIONS (3D) DU ROBOT MOBILE AUTONOME HILARE. CE SYSTEME EST COMPOSE D'UNE CAMERA MATRICIELLE A SEMICONDUCTEURS, D'UN TELEMETRE LASER ET D'UNE STRUCTURE MECANIQUE ASSURANT LA DEFLEXION DU FAISCEAU LASER. DANS CE MEMOIRE SONT DECRITS: LA CONCEPTION DE LA STRUCTURE DEFLECTRICE; LE LOGICIEL DE TRAITEMENT DES IMAGES VIDEO MULTINIVEAUX BASE...

  20. Codification of LMFBR rules and comparison of codes

    International Nuclear Information System (INIS)

    Faure, O.; Debaene, J.P.

    1993-01-01

    The first part of this report presents the basic RCC-MR (regles de conception et de construction des materiels mecaniques des ilots nucleaires, reacteurs a neutrons rapides) design rules and their purpose. The second part is a qualitative comparison between RCC-MR, Code case N47 (ASME) and ETSDG Guide (MONJU Guide), made on the following topics: negligible creep test, ratcheting, creep fatigue, buckling, piping rules. An outline is given on improvements to RCC-MR rules now in progress

  1. Khokhlov Zabolotskaya Kuznetsov type equation: nonlinear acoustics in heterogeneous media

    Science.gov (United States)

    Kostin, Ilya; Panasenko, Grigory

    2006-04-01

    The KZK type equation introduced in this Note differs from the traditional form of the KZK model known in acoustics by the assumptions on the nonlinear term. For this modified form, a global existence and uniqueness result is established for the case of non-constant coefficients. Afterwards the asymptotic behaviour of the solution of the KZK type equation with rapidly oscillating coefficients is studied. To cite this article: I. Kostin, G. Panasenko, C. R. Mecanique 334 (2006).

  2. Nouvelles bornes et estimations pour les milieux poreux à matrice rigide parfaitement plastique

    Science.gov (United States)

    Bilger, Nicolas; Auslender, François; Bornert, Michel; Masson, Renaud

    We derive new rigorous bounds and self-consistent estimates for the effective yield surface of porous media with a rigid perfectly plastic matrix and a microstructure similar to Hashin's composite spheres assemblage. These results arise from a homogenisation technique that combines a pattern-based modelling for linear composite materials and a variational formulation for nonlinear media. To cite this article: N. Bilger et al., C. R. Mecanique 330 (2002) 127-132.

  3. The Application of Various Nondestructive Testing Methods to Fuel Elements of the Orgel Type; Application des Differentes Methodes d'Essais Non Destructifs aux Elements Combustibles du Type Orgel; Primenenie razlichnykh nedestruktivnykh metodov ispytanij k toplivnym ehlementam tipa ''orgel''; Aplicacion de Distintos Metodos de Ensayo No Destructivo a los Elementos Combustibles de Tipo Orgel

    Energy Technology Data Exchange (ETDEWEB)

    Bonnet, P.; Jansen, J. [EURATOM, C.C.R., Ispra (Italy)

    1965-09-15

    . There is a device making it possible to examine four or six fuel elements simultaneously, or two or three separately. Standard radiographic tests. Particular stress is laid on the study of welds, and the limits of the experimental conditions in order to obtain good definition are given. In conclusion, the authors present a plan for a semi-industrial inspection system, describing the various possibilities for treatment, and try to define a general policy of non-destructive tests applied to fuel elements. (author) [French] Le memoire presente les differentes methodes employees pour la detection des defauts dans les tubes de gaine des elements combustibles (defauts de type dimensionnel ou defauts structuraux). Les auteurs evoquent egalement les tests finaux sur elements combustibles complets, en particulier: radiographie des soudures et tests d'etanchete. Ce sujet a deja ete partiellement traite. La recherche des caracteristiques dimensionnelles sur tube de gaine lisse en poudre d'aluminium frittee (SAP) a fait l'objet de recherches assez poussees. En particulier: 1. Mesures des diametres internes et externes par utilisation de capteurs pneumatiques et enregistrement des resultats; 2. Mesures des epaisseurs par utilisation, soit des ultrasons en methode de resonance, soit des rayons y (contrat EURATOM - Istituto Sperimentale Metalli Leggeri); 3. Controle de la fleche; 4. Tests sur tubes a ailettes. La detection des defauts sur tube de gaine lisse a egalement fait l'objet de travaux et un critere de rejet a ete adopte suivant l'utilisation future des tubes de gaines. a) La creation de defauts artificiels en fonction de la nocivite des defauts reels dans la poudre d'aluminium frittee est expliquee dans le memoire. Cette etude a montre, en effet, une grande sensibilite aux defauts du type longitudinal crees generalement lors de la transformation par de grosses inclusions. b) Tests par ultrasons. Defauts longitudinaux: Une comparaison entre la methode a deux capteurs et la

  4. Some aspects of nuclear graphite production in France; Etude generale sur les graphites nucleaires produits en France

    Energy Technology Data Exchange (ETDEWEB)

    Gueron, J; Hering, H [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Legendre, A [Pechiney, 75 - Paris (France)

    1958-07-01

    1) Manufacturing: A summary and results on the CEA-Pechiney purification process are given. Variations in the preparation of green pastes and their effects on graphitized material are described. 2) Physical and mechanical properties: Results are given on: - Statistics of dimensional variatior products having square cross-section. - Statistical variation of thermal expansion coefficients and of electrical conductivity. - Density of normals to carbon layer planes and their connexion with thermal expansion. - Stress-strain cycles and conclusions drawn therefrom. - Mechanical resistance and gas permeability of items for supporting fuel elements. 3) Behaviour under radiation: Alteration under radiation of French graphites irradiated either in G1 pile or in experimental piles, and thermal annealing of those alterations, are given. (author)Fren. [French] 1) Fabrication: On resume le procede d'epuration CEA-PECHINEY, ainsi que diverses modalites de preparation des pates et on expose les resultats obtenus. 2) Proprietes physiques et mecaniques: On indique le resultat d'etudes sur: - la statistique des dimensions de produits a section carree. - celle des variations des coefficients de dilatation thermique et de la conductibilite electrique. - la densite des normales aux plans graphitiques et leur connexion avec la dilatation thermique. - la compression mecanique du graphite. - la solidite mecanique et la permeabilite aux gaz de pieces destinees a supporter des cartouches de combustible. 3) Tenue sous rayonnement: Modification sous rayonnement des graphites fran is irradies soit dans la pile G1, soit dans des piles experimentales, et guerison thermique de ces modifications. (auteur)

  5. Cooling and spreading of corium during its fall into water in a pressurised water nuclear plant severe accident: description of mechanical and thermal interactions in a three phase flow during spreading of cold or heated spheres in a liquid pool; Refroidissement et dispersion du corium lors de sa chute dans l'eau pendant un accident severe de reacteur nucleaire a eau pressurisee: description des interactions mecaniques et thermiques en ecoulement triphasique lors de la dispersion de spheres solides froides ou chaudes dans un bain liquide

    Energy Technology Data Exchange (ETDEWEB)

    Duplat, F

    1998-10-26

    In the frame of nuclear safety studies about corium and water interactions, we address spreading and cooling stage of corium fragments in a liquid pool. Considering the complexity of encountered flow regimes and mechanical and thermal interactions coupling, modelling validation is based on a thermal-hydraulic computer code (MC3D). A bibliographical study shows that classical modelling of three phase flow is based on constitutive laws already established in the case of two phase flow. The present study states a complete analysis of BILLEAU experiments and defines a characterisation method for a sphere cloud. Some complementary QUEOS experiments are also described. Mechanical interaction terms such as added mass, lift and turbulent dispersion have been presented in the frame of a three phase flow and their influence has been tested in numerical simulations of BILLEAU tests. The effect of film vapour overheat, as well as particle diameter evolution have been studied. Moreover a radiative heat transfer modelling developed in Karlsruhe research centre (FZK) has been analysed and completed. Numerical simulations achieved for this study show that mechanical and thermal behaviour of the system are actually coupled. Taking into account lift and turbulent dispersion terms as well as heat transfer modifications all wed better results. This study also presents some considerations about flow regimes identification as a preliminary for studies about numerical diffusion that was already estimated in the present state of the computer code MC3D. (author)

  6. Economic study of an installation for uranium isotope separation by gaseous diffusion; Etude economique d'une installation de separation des isotopes de l'uranium par diffusion gazeuse

    Energy Technology Data Exchange (ETDEWEB)

    Bilous, O [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1958-07-01

    This report describes the major problems which arise in the choice of characteristics required in a gaseous diffusion installation for the separation of uranium isotopes. This choice depends largely on economic evaluations, and also on considerations of simplicity. The choice of working pressures and of the characteristics of the membrane are described, as are the possible alternatives regarding the structure of the stages and the problems of control. (author) [French] Ce rapport decrit les problemes majeurs qui se posent dans le choix des caracteristiques d'une installation de diffusion gazeuse destinee a la separation des isotopes de l'uranium. Ce choix depend en grande partie d'evaluations economiques et repose egalement sur des considerations de simplicite. On decrit ainsi le choix des pressions d'operation, celui des caracteristiques de la barriere, les alternatives possibles concernant la structure des etages et les problemes de regulation. (auteur)

  7. Determination of the 20 MeV linear accelerator, new injector for the synchrotron Saturne. Choice of the electrical and dynamical particle parameters; Determination de l'accelerateur lineaire de 20 MeV, nouvel injecteur du synchrotron Saturne. Choix des parametres electriques, dynamique des particules

    Energy Technology Data Exchange (ETDEWEB)

    Prome, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1968-12-15

    This report takes place in the general determination of the 20 MeV linear accelerator which will be the new Saturne injector; it deals with particle dynamics. Starting from beam requirements at the output of the linac, cells lengths with variable synchronous phase angle, buncher and de-buncher parameters, beam emittances at the output in several phase spaces are successively determined. (author) [French] Dans le contexte general de la determination de l'accelerateur lineaire de 20 MeV, nouvel injecteur du synchrotron Saturne, ce rapport traite de la partie relative au mecanisme de l'acceleration des particules; a partir des caracteristiques souhaitees pour le faisceau a la sortie de cet accelerateur, on determine successivement les longueurs des cellules, compte tenu du choix d'un angle de phase synchrone variable, les caracteristiques du groupeur et du degroupeur et les emittances du faisceau en sortie dans les differents plans de phase. (auteur)

  8. Caracterisation sociodemographique, clinique et criminologique d?une population de 210 meurtriers

    OpenAIRE

    2009-01-01

    Resume Cet article, de nature essentiellement descriptive, interroge les caracteristiques sociodemographiques, cliniques et criminologiques d?une population de 210 meurtriers examines par deux experts psychiatres angevins pendant une periode de 30 ans. Les meurtriers de notre serie sont majoritairement des hommes (73 %) d?age jeune, 33 ans en moyenne, sans emploi (51 %), vivant seuls au moment des faits (49 %). Ils ont des antecedents psychiatriques dans deux tiers des cas et des a...

  9. Hydrogen storage: current knowledge and used techniques. An overview on this research topic at the LMARC of Besancon

    International Nuclear Information System (INIS)

    Chapelle, D.; Perreux, D.; Thiebaud, F.; Robinet, P.

    2007-01-01

    In a first part are presented, with examples, the different means of hydrogen storage in order to establish a comparison in performances, maturity and safety. The second part presents the studies carried out in the Laboratoire de Mecanique Appliquee Raymond Chaleat de Besancon, and more particularly of the team 'Mechanical Properties of Materials', for hydrogen storage. This Laboratory aims to develop, design and optimize, in a thermomechanical point of view, the containment intended to store hydrogen under pressure but the solid compounds systems too. (O.M.)

  10. Combining Approach in Stages with Least Squares for fits of data in hyperelasticity

    Science.gov (United States)

    Beda, Tibi

    2006-10-01

    The present work concerns a method of continuous approximation by block of a continuous function; a method of approximation combining the Approach in Stages with the finite domains Least Squares. An identification procedure by sub-domains: basic generating functions are determined step-by-step permitting their weighting effects to be felt. This procedure allows one to be in control of the signs and to some extent of the optimal values of the parameters estimated, and consequently it provides a unique set of solutions that should represent the real physical parameters. Illustrations and comparisons are developed in rubber hyperelastic modeling. To cite this article: T. Beda, C. R. Mecanique 334 (2006).

  11. Nonlinear behavior of matrix-inclusion composites under high confining pressure: application to concrete and mortar

    Science.gov (United States)

    Le, Tuan Hung; Dormieux, Luc; Jeannin, Laurent; Burlion, Nicolas; Barthélémy, Jean-François

    2008-08-01

    This paper is devoted to a micromechanics-based simulation of the response of concrete to hydrostatic and oedometric compressions. Concrete is described as a composite made up of a cement matrix in which rigid inclusions are embedded. The focus is put on the role of the interface between matrix and inclusion which represent the interfacial transition zone (ITZ). A plastic behavior is considered for both the matrix and the interfaces. The effective response of the composite is derived from the modified secant method adapted to the situation of imperfect interfaces. To cite this article: T.H. Le et al., C. R. Mecanique 336 (2008).

  12. Some measurements of time and space correlation in wind tunnel

    Science.gov (United States)

    Favre, A; Gaviglio, J; Dumas, R

    1955-01-01

    Results are presented of research obtained by means of an apparatus for measurement of time and space correlation and of a spectral analyzer in the study of the longitudinal component of turbulence velocities in a wind tunnel downstream of a grid of meshes. Application to the case of a flat-plate boundary layer is illustrated. These researches were made at the Laboratoire de Mecanique de l'Atmosphere de l'I.M.F.M. for the O.N.E.R.A.

  13. Amélioration des performances du procédé de soudage TIG sur un acier au carbone et un alliage d'aluminium par dépôt de silice

    Science.gov (United States)

    Sire, Stéphane; Marya, Surendar

    This Note presents ways to improve the weld penetration potential of TIG process by optimising silica application around the joints in a plain carbon steel and an aluminium alloy 5086. Whereas for plain carbon steels, full coverage of joint improves penetration, the presence of a blank zone around the joint in the flux coating on aluminium 5086 using AC-TIG seems to be the best solution for cosmetic and deep welds. To cite this article: S. Sire, S. Marya, C. R. Mecanique 330 (2002) 83-89.

  14. Singularités de la rhéologie de l'air humide saturé et diffusion moléculaire dans les milieux nuageuxSingularities in the rheology of saturated humid air, and molecular diffusion in cloods

    Science.gov (United States)

    Bois, Pierre-Antoine

    Under realistic assumptions, we propose a thermodynamical formalism providing, for the moist-saturated air (cloudy air), a generalized Fick's law. This Fick's law leads to a double diffusive rheology with Dufour effect. The form taken by the energy equation is slightly different from the classical form used in convection problems. We compare the equations with those of the convection in moist unsaturated air (the Dufour effect and all double diffusive effects disappear in this case). As application we demonstrate some consequences of this diffusion in cloudy convection. To cite this article: P.A. Bois, C. R. Mecanique 330 (2002) 627-632.

  15. Design methods and criteria recommended by the RAMSES committee

    International Nuclear Information System (INIS)

    Jakubowicz, H.; Moulin, D.; Petrequin, P.; Tortel, J.; Schaller, K.

    1980-09-01

    The design of structures of LMFBR in France must comply with the national regulations and takes into account the rules adopted by other countries but these rules need complements. The French Atomic Energy Commission has founded a committee named RAMSES (which states for 'Regles d'Analyse Mecanique des Structures') in order to write recommendations to give out the needed informations on design rules based on all the available background experience. The elastic follow up problem has received great attention and a recommendation was already printed. Of great concern in elevated temperature is a creep fatigue investigation. A creep fatigue design method adapted to materials used is being set up

  16. Analyse d'un problème viscoélastique avec compliance normale, frottement et diffusion d'usure

    Science.gov (United States)

    Shillor, Meir; Sofonea, Mircea; Telega, J. Joachim

    2003-06-01

    We consider a quasistatic problem of frictional contact between a viscoelastic body and a moving foundation. The contact is with wear and is modeled by normal compliance and a law of dry friction. The novelty in the model is that it allows for the diffusion of the wear debris over the potential contact surface. Such kind of phenomena arise in orthopaedic biomechanics and influence the properties of joint prosthesis. We derive a weak formulation of the problem and state that, under a smallness assumption on the problem data, there exists a unique weak solution for the model. To cite this article: M. Shillor et al., C. R. Mecanique 331 (2003).

  17. Contribution to the microwave characterisation of superconductive materials by means of sapphire resonators; Contribution a la caracterisation hyperfrequence de materiaux supraconducteurs par des resonateurs-saphirs

    Energy Technology Data Exchange (ETDEWEB)

    Hanus, Xavier

    1993-12-06

    The objective of this research thesis is to find a compact resonant structure which would allow the residual surface impedance of superconductive samples to be simply, quickly and economically characterised. The author first explains why he decided to use a sapphire single-crystal as inner dielectric, given some performance reached by resonant structures equipped with such inner dielectrics, and given constraints adopted from the start. He explains the origin of microwave losses which appear in this type of resonant structure, i.e. respectively the surface impedance as far as metallic losses are concerned, and the sapphire dielectric loss angle for as far as dielectric losses are concerned. The experimental installation and the principle of microwave measurements are described. The performance of different possible solutions of resonant structures from starting criteria is presented. The solution of the cavity-sapphire with a TE{sub 011} resonant mode is derived [French] Le but de cette etude est de trouver une structure resonnante compacte permettant de caracteriser simplement, rapidement et economiquement l'impedance de surface residuelle d'echantillons supraconducteurs. Les contraintes de mise en oeuvre et les performances atteintes par des resonateurs avec saphirs synthetiques justifient le choix d'un tel dielectrique a faible angle de perte. L'evaluation des performances experimentales appuyee par des modelesanalytiques permet de rejeter differentes solutions. Ainsi les resonateurs fermes avec saphirs minces sont rejetes en raison des mauvais contacts metalliques. Les resonateurs ouverts avec saphirs minces et epais sont egalement rejetes, meme pour les modes de resonance en principe confines, en raison des pertes par rayonnement. La seule solution est donc d'utiliser une cavite-saphir TE{sub 011} qui offre une configuration de champs naturellement confines. Des mesures sur une premiere cavite en niobium massif ont permis de selectionner un saphir obtenu par

  18. Model of contract of purchase of the electric power produced by facilities that use the mechanical energy of the wind, and benefiting from the electricity purchase obligation. Established after enforcement of the article 5 of the decree from May 10, 2001 and approved by the minister attended to energy; Modele de contrat d'achat de l'energie electrique produite par les installations utilisant l'energie mecanique du vent et beneficiant l'obligation d'achat d'electricite. Etablie en application de l'article 5 du decret du 10 mai 2001 et approuve par le Ministre charge de l'electricite

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-07-01

    This model of contract comprises 2 parts. The first part describes the general conditions of electric power purchase: aim of the contract, connection to the grid and delivery point, producer's facility, reciprocal commitments and stoppages for maintenance purpose, energy and power metering and control, energy delivery, payment for the purchased power (tariffs, energy efficiency incentives, conditions, control, tariffs indexing), taxes, payments, contract enforcement, date line, suspension, modification or cancellation, conciliation in case of dispute. A recall of the tariffs mentioned in the by-law from June 8, 2001, of the approximation rules and a model of certificate are given in appendixes. The second part gives some complements to the general conditions (purchaser and producer corporate, characteristics of the facility, details about the connection and delivery point, description of the metering system, tariffs of purchase and indexing, payment of bills, contract characteristics, subscription for a power supply contract). (J.S.)

  19. Uranium Ore and Concentrate Sampling; Echantillonnage des Minerais et des Concentres d'Uranium; Otbor prob uranovoj rudy i kontsentratov; Muestreo de Minerales y Concentrados de Uranio

    Energy Technology Data Exchange (ETDEWEB)

    McGinley, F. E.; Brown, D. L.; Langridge, R. W. [United States Atomic Energy Commission, Grand Junction, CO (United States)

    1966-02-15

    upon the atmosphere to which they are exposed, special sub-sampling, drying, and sample preparation procedures were continuously developed to improve the accuracy and precision of the overall purchase sampling. Extensive use was made of statistics to analyse and interpret measurement and sampling evaluation data. (author) [French] Les services de la Commission de l'energie atomique situes a Grand Junction (Colorado) sont charges de fournir de grandes quantites d'uranium naturel sous forme de minerais ou de concentres. Les methodes utilisees pour echantillonner les minerais sont necessairement differentes de celles utilisees pour les concentres. Les auteurs etudient les differentes operations de mesure et d'echantillonnage pour les minerais et les concentres, en tenant plus particulierement compte de l'exactitude et de la precision de ces operations. Entre 1948 et 1964, 58 millions de tonnes de minerais au total ont ete echantillonnees dans 40 installations differentes d echantillonnage mecanique situees dans l'ouest des Etats-Unis. Toutes ces installations ont du peser, echantillonner et analyser le minerai selon des methodes agreees par la Commission de l'energie atomique. Les principes courants d'echantillonnage de minerai utilises depuis des annees dans l'industrie miniere sont appliques. Il est toutefois procede a des echantillonnages de controle et a d'autres essais pour s'assurer que la teneur en uranium des differents minerais echantillonnes est determinee avec toute la precision economiquement possible. Au cours des 17 dernieres annees, des concentres contenant environ 129 000 tonnes d'U{sub 3}O{sub 8} ont ete achetes a des producteurs du pays. Cet uranium se trouvait dans 10 000 lots environ, dont chacun a ete pese, echantillonne et analyse selon des methodes soigneusement controlees. Ces lots ont ete expedies aux installations d'echantillonnage de Grand Junction ou de Weldon Spring (Missouri), toutes deux propriete de la Commission de l'energie atomique mais

  20. Universal Instability in a Thermal Plasma Device (Q-Machine); Instabilite Universelle dans une Machine a Plasma Thermique (Machine-Q); Issledovaniya universal'noj neustojchivosti v ustrojstve dlya termicheski ionizovannoj plazmy; Inestabilidad Universal en un Dispositivo de Plasma Termico (Maquina Q)

    Energy Technology Data Exchange (ETDEWEB)

    Lashinsky, H. [University Of Maryland, College Park, MD (United States)

    1966-04-15

    , revealed a number of non-linear effects such as ''mode jumping'' and ''mode locking''. These non-linear phenomena have been analyzed by generalizing standard methods of non-linear mechanics to distributed systems and are found to be related to similar phenomena observed in optical masers and lumped-parameter vacuumtube systems. (author) [French] La colonne entierement ionisee dans une machine a plasma thermique (machine-Q) fournit un milieu qui convient l'etude de l'instabilite universelle (onde de derive) produite par l'effet combine du rayon de Larmor fini des ions et du gradient de densite perpendiculaire au champ magnetique de confinement. On peut faire varier les parametres sans dimension appropries dans un intervalle tel que les resultats puissent etre gradues pour permettre des comparaisons avec des'plasmas presentant un interet thermonucleaire, et on peut exciter l'instabilite sous controle par un ajustement approprie des conditions de couche aux plaques metalliques terminales en recourant aux techniques de controle de couche qui sont examinees en meme temps queja theorie sur laquelle elles reposent. En recourant a ces techniques; on peut maintenir l'amplitude d'oscillation a des niveaux arbitrairement bas et on peut suivre le comportement de l'instabilite dans son passage du regime 'quasi lineaire' de basse amplitude (e Empty-Set /kT Tilde-Operator 10{sup -3}) - caracterise par un spectre monochromatique de 'mode ferme' -au regime non lineaire, puis a un etat faiblement turbulent (e Empty-Set /kT Less-Than-Or-Equivalent-To 1) - caracterise par un spectre de bruit 'hache'. Une methode nouvelle 'd'agencement en grille' fournit un tableau complet du developpement de l'instabilite et de la transition vers la turbulence. Les caracteristiques fondamentales de l'instabilite, determinees experimentalement, telles que les frequences de mode, la direction de la propagation azimutale, les proprietes de coherence, l'indep'endance a . l'egard de la densite, la dependance a l

  1. Contribution to a research on electron beam welding of metals; Contribution a l'etude de la soudure des metaux par faisceau d'electrons

    Energy Technology Data Exchange (ETDEWEB)

    Stohr, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-03-15

    les qualites metallurgiques des ensembles soudes. Cette etude a amene a definir un canon a electrons aussi adapte que possible a la realisation de soudures, tant au point de vue comportement, notamment lors des passages de la pression atmospherique a la pression reduite de 10{sup -5} Torr necessaire pour la realisation de la soudure, qu'au point de vue de la facilite du reglage des divers parametres de soudure necessaire pour l'etude envisagee. La variation des parametres de soudure montre que la forme de la zone fondue, passe du segment de cercle a celle d'un triangle a grand elancement. Ce qui implique un changement continu du mode de transmission de chaleur. Des essais ont ete realises pour confirmer cette maniere de voir, notamment l'obtention, des isothermes en regime dynamique et la comparaison de ces isothermes avec celles relevees en utilisant le procede de soudure par argon arc. Le bilan thermique de l'energie fournie a la piece, de l'energie necessaire a la fusion et de l'energie perdue (conduction, rayonnment, vaporisation) a ete etabli. Ces resultats mettent en evidence que la quasi totalite de l'energie est utilisee pour la fusion, que les diverses pertes sont negligeables et que la transmission de la chaleur ne peut s'etablir par conduction dans la piece pendant le temps 'soudure' lorsqu'on opere dans des conditions de regime telles que la zone fondue presente une section faible, caracteristique essentielle du procede. Ces essais confirment egalement que la cavite creusee par le faisceau d'electrons est libre de metal fondu, ce qui permet le passage des electrons dont la penetration dans la matiere est negligeable. Cette maniere de voir est confirmee par des macrographies sur pieces fixes sur lesquelles ont ete executes des points de soudure tres courts: ces macrographies montrent l'existence d'un canal central. Les essais effectues en regime dynamique confirment egalement l'existence de ce canal, lorsque en cours de soudure on interrompt brutalement le

  2. VISIT OF BELGIAN FIRMS AT CERN: 2 - 3 APRIL 2003

    CERN Multimedia

    2003-01-01

    14:00 to 17:30 hrs Wednesday 2nd April 09:00 to 17:30 hrsThursday 3rd April Individual interviews will take place in different conference rooms or in technicians' offices. The firms will contact relevant users/technicians but any user wishing to make contact with a particular firm is welcome to use the contact details which are available from each secretariat of division or from the Purchasing web pages at the following URL http://spl-div.web.cern.ch/spl-div/member_states/exhibitions_visits.htm List of Companies: 1. Advanco13. Gillam-Fei SA25. Opticable SA 2. Balteau SA14. G-Tec SA26. Orthodyne SA 3. Barco NV15. Groupe Hamon27. Polmans Atelier Mecanique 4. Blonde SA16. HTMS NV28. RESARM Engineering Plastics SA 5. Britte SA17. IMCORP Europe29. SAMTECH 6. Cablerie d'Eupen18. Inductive Systems Europe NV30. Schreder - Hazemeyer SA 7. Cegelec SA19. Link Software31. SYREG Sprl 8. Clever House20. MACQ Electronique SA32. Thales Communications Belgium 9. SA Coppee - Courtoy NV21. Mecanique de Precision pour Equipm...

  3. VISIT OF BELGIAN FIRMS AT CERN: 2 - 3 APRIL 2003

    CERN Multimedia

    2003-01-01

    14:00 to 17:30 hrs Wednesday 2nd 09:00 to 17:30 hrs Thursday 3rd Individual interviews will take place in different conference rooms or in technicians' offices. The firms will contact relevant users/technicians but any user wishing to make contact with a particular firm is welcome to use the contact details which are available from each secretariat of division or from the Purchasing web pages at the following URL http://spl-div.web.cern.ch/spl-div/member_states/exhibitions_visits.htm. List of Companies: 1. Advanco18. Link Software 2. Balteau SA19. MACQ Electronique SA 3. Barco NV20. Mecanique de Precision pour Equipments 4. Blonde SA21. Mecasoft SA 5. Britte SA22. Mockel SCA 6. Cablerie d'Eupen23. Notifier Benelux 7. Cegelec SA24. Opticable SA 8. SA Coppee - Courtoy NV25. Orthodyne SA 9. Denys NV26. Polmans Atelier Mecanique 10. DSI Sprl27. RESARM Engineering Plastics SA 11. Engetec SA28. SAMTECH 12. Gillam-Fei SA29. Schreder - Hazemeyer SA 13. G-Tec SA30. SYREG Sprl 14. Groupe Hamon31. Thales Communication...

  4. VISIT OF BELGIAN FIRMS AT CERN: 2 - 3 APRIL 2003

    CERN Multimedia

    2003-01-01

    14:00 to 17:30 hrs Wednesday 2nd 09:00 to 17:30 hrs Thursday 3rd Individual interviews will take place in different conference rooms or in technicians' offices. The firms will contact relevant users/technicians but any user wishing to make contact with a particular firm is welcome to use the contact details which are available from each secretariat of division or from the Purchasing web pages at the following URL http://spl-div.web.cern.ch/spl-div/member_states/exhibitions_visits.htm. List of Companies: 1. Advanco18. Link Software 2. Balteau SA19. MACQ Electronique SA 3. Barco NV20. Mecanique de Precision pour Equipments 4. Blonde SA21. Mecasoft SA 5. Britte SA22. Mockel SCA 6. Cablerie d'Eupen23. Notifier Benelux 7. Cegelec SA24. Opticable SA 8. SA Coppee - Courtoy NV25. Orthodyne SA 9. Denys NV26. Polmans Atelier Mecanique 10. DSI Sprl27. RESARM Engineering Plastics SA 11. Engetec SA28. SAMTECH 12. Gillam-Fei SA29. Schreder - Hazemeyer SA 13. G-Tec SA30. SYREG Sprl30. SYREG Sprl 14. Groupe Hamon31. Thale...

  5. Some considerations of the energy spectrum of odd-odd deformed nuclei; Quelqes considerations sur le spectre d'energie des noyaux impair-impair deformes

    Energy Technology Data Exchange (ETDEWEB)

    Alceanu-G, Pinho de; Picard, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-07-01

    The odd-odd deformed nuclei are described as a rotator plus two odd nucleons moving in orbitals {omega}{sub p} and {omega}{sub n} of the deformed potential. We investigate the energies and wave functions of the various states of the ({omega}{sub p}, {omega}{sub n}) configurations by calculating and numerically diagonalizing the Hamiltonian matrix (with R.P.C. and residual interactions). The Gallagher-Mosskowski coupling rules ana the abnormal K equals 0 rotational bands are discussed. (authors) [French] Les noyaux impair-impairs deformes sont decrits comme un rotateur plus deux nucleons non apparies dans les orbites {omega}{sub p} et {omega}{sub n} du potentiel deforme. Nous etudions le spectre d'energie et les fonctions d'onde des configurations ({omega}{sub p}, {omega}{sub n}) en tenant compte de l'interaction particule-rotation et de la force residuelle entre les deux nucleons celibataires.

  6. Treatment, as radio-active waste, of large pieces of {proportional_to}-contaminated apparatus (1962); Conditionnement en tant que dechet radioactif de gros materiel contamine en {proportional_to} (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Boutot, P; Capitaine, A; Giachetto, I [Commissariat a l' Energie Atomique, Centre de Production de Plutonium, Marcoule (France). Centre d' Etudes Nucleaires

    1962-07-01

    Two solutions have been adopted: - removal of the material from its original container, treatment in a special container; - treatment of the material directly inside its original protective packing. The treatment of a fluorination oven illustrates the second process. After a thorough cleaning of the enclosure, the oven is fixed in and the contamination held in place by a varnish. The assembly is placed in a special container and covered with shaken-down concrete. The container is shut by means of a welded cover. The operations are carried out under reduced pressure. At the end of this process it is impossible to detect any residual radioactivity. (authors) [French] Deux solutions ont ete adoptees: - extraire le materiel de son enveloppe d'origine et le conditionner dans un container special; - conditionner le materiel directement a l'interieur de la protection d'origine. Le conditionnement d'un four de fluoration illustre le deuxieme procede. Apres un nettoyage complet de l'enceinte, le four en a ete rendu solidaire et la contamination a ete fixee au moyen d'un vernis. L'ensemble a ete place dans un container special et enrobe de beton vibre. Le container a ete ferme par un couvercle soude. L'ensemble des operations a ete realise sous depression. A la suite de ces operations aucune activite residuelle n'a ete decelee. (auteurs)

  7. Use of cadmium in solution in the EL 4 reactor moderator irreversible fixing of cadmium on the metallic surfaces; Utilisation du cadmium en solution dans le moderateur du reacteur EL 4 - fixation irreversible du cadmium sur les surfaces metalliques

    Energy Technology Data Exchange (ETDEWEB)

    Croix, O; Paoli, O; Lecomte, J; Dolle, L; Gallic, Y [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    In the framework of research into the poisoning of the EL-4 reactor by cadmium sulphate, measurements have been made by two different methods of the residual amounts of cadmium liable to be fixed irreversibly on the surfaces in contact with the heavy water. A marked influence of the pH has been noticed. The mechanism of the irreversible fixing is compatible with the hypothesis of an ion-exchange in the surface oxide layer. In a sufficiently wide range of pH the cadmium thus fixed causes very little residual poisoning. The stability of the cadmium sulphate solutions is however rather low in the conditions of poisoning. (authors) [French] Dans le cadre des etudes sur l'empoisonnement du reacteur EL-4 par le sulfate de cadmium, les quantites residuelles de cadmium susceptibles de se fixer irreversiblement sur les parois que mouillerait l'eau lourde, ont ete mesurees experimentalement par deux methodes differentes. On observe une influence nette du pH. Le mecanisme de la fixation irreversible est compatible avec l'hypothese d'un echange d'ions dans la pellicule d'oxyde superficielle. Dans des limites suffisamment larges de pH, la cadmium ainsi fixe n'occasionne pas d'empoisonnement residuel important. La stabilite des solutions de sulfate de cadmium dans les conditions de l'empoisonnement est cependant mediocre. (auteurs)

  8. Qualitative microanalysis of rare earths (ceric and yttric), of thorium and uranium in minerals; Microanalyse qualitative des terres rares (ceriques et yttriques), du thorium et de l'uranium dans les mineraux

    Energy Technology Data Exchange (ETDEWEB)

    Agrinier, H [Commissariat a l' Energie Atomique, Saclay(France). Centre d' Etudes Nucleaires

    1955-07-01

    We propose in this study to give a general method of attack of the niobio-titanates, niobio-tantalates, oxides, phosphates or silicates containing rare earths (ceric or yttric), uranium or thorium, and to put in evidence these different elements by microchemical reactions giving crystallization or the characteristic colorations. (M.B.) [French] Nous nous proposons dans cette etude de donner une methode generale d'attaque des niobotitanates, niobotantalates, oxydes, phosphates ou silicates contenant des terres rares (ceriques ou yttriques), de l'uranium ou du thorium, et de mettre en evidence ces differents elements au moyen de reactiors microchimiques donnant des cristallisations ou des colorations caracteristiques. (MB)

  9. Reconnaissance invariante d'objets 3-D et correlation SONG

    Science.gov (United States)

    Roy, Sebastien

    Cette these propose des solutions a deux problemes de la reconnaissance automatique de formes: la reconnaissance invariante d'objets tridimensionnels a partir d'images d'intensite et la reconnaissance robuste a la presence de bruit disjoint. Un systeme utilisant le balayage angulaire des images et un classificateur par trajectoires d'espace des caracteristiques permet d'obtenir la reconnaissance invariante d'objets tridimensionnels. La reconnaissance robuste a la presence de bruit disjoint est realisee au moyen de la correlation SONG. Nous avons realise la reconnaissance invariante aux translations, rotations et changements d'echelle d'objets tridimensionnels a partir d'images d'intensite segmentees. Nous utilisons le balayage angulaire et un classificateur a trajectoires d'espace des caracteris tiques. Afin d'obtenir l'invariance aux translations, le centre de balayage angulaire coincide avec le centre geometrique de l'image. Le balayage angulaire produit un vecteur de caracteristiques invariant aux changements d'echelle de l'image et il transforme en translations du signal les rotations autour d'un axe parallele a la ligne de visee. Le classificateur par trajectoires d'espace des caracteristiques represente une rotation autour d'un axe perpendiculaire a la ligne de visee par une courbe dans l'espace. La classification se fait par la mesure de la distance du vecteur de caracteristiques de l'image a reconnaitre aux trajectoires stockees dans l'espace. Nos resultats numeriques montrent un taux de classement atteignant 98% sur une banque d'images composee de 5 vehicules militaires. La correlation non-lineaire generalisee en tranches orthogonales (SONG) traite independamment les niveaux de gris presents dans une image. Elle somme les correlations lineaires des images binaires ayant le meme niveau de gris. Cette correlation est equivalente a compter le nombre de pixels situes aux memes positions relatives et ayant les memes intensites sur deux images. Nous presentons

  10. The interaction of circularly polarised electromagnetic waves with a plasma; Interaction d'ondes electromagnetiques a polarisation circulaire avec un plasma

    Energy Technology Data Exchange (ETDEWEB)

    Consoli, T; Legardeur, R; Slama, L [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-07-01

    The interaction of left and right handed circularly polarised waves with a plasma are studied. The individual trajectories of charges of both signs are traced with a analogical simulator. Applications to plasma heating and diagnostic are deduced. (author) [French] On etudie l'interaction des ondes a polarisation circulaire droite ou gauche avec un plasma. Les trajectoires individuelles des charges sont tracees a l'aide d'un dispositif analogique. On en deduit les applications au chauffage d'un plasma et a la mesure de ses parametres caracteristiques. (auteur)

  11. Proton ejection project for Saturne; Projet d'ejection des protons de saturne

    Energy Technology Data Exchange (ETDEWEB)

    Bronca, G; Gendreau, G

    1959-07-01

    The reasons for choosing the ejection system are given. The characteristics required for the ejected beam are followed by a description of the ejection process, in chronological order from the viewpoint of the protons: movement of the particles, taking into account the various elements which make up the system (internal magnet, external magnet, quadrupoles, ejection correction coils, thin and thick cables,...) and specification of these elements. Then follows an estimation of the delay in manufacture and the cost of the project. Finally, the characteristics of the magnets and quadrupoles are listed in an appendix. (author) [French] On donne d'abord les raisons du choix du systeme d'ejection, puis le principe. Apres les caracteristiques requises pour le faisceau ejecte, on decrit le processus d'ejection selon l'ordre chronologique vu par les protons: mouvement des particules compte tenu des divers elements composant le systeme (aimant interne, aimant externe, quadrupoles, enroulements correcteurs ejection, cibles mince et epaisse,. ..) et cahier de charge de ces elements. On estime, ensuite les delais de realisation et le cout du projet. Enfin, un resume des caracteristiques des aimants et quadrupoles est donne en appendice. (auteur)

  12. Experience gained in two years operation of G1; Experience acquise au cours de deux ans de fonctionnement du reacteur G1

    Energy Technology Data Exchange (ETDEWEB)

    de, Rouville; Pascal, [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Scalliet, [Electricite de France (EDF), 75 - Paris (France)

    1958-07-01

    Technical specifications in respect of the first plutonium generating graphite reactor, the G1 at Marcoule, were stated in a paper read at the first Geneva Conference in 1955. We shall not therefore deal further with the technical characteristics of G1 in the present note, but rather propose to define - in the characteristic fields we think will be of major interest to foreign specialists - the results obtained in two and a half years operation since G1 first became critical on january 7, 1956. (author)Fren. [French] Les caracteristiques techniques du premier reacteur plutonigene, au graphite, de Marcoule, G1, ont ete donnees dans une communication presentee a la premiere conference de Geneve, en 1955. Nous n'y reviendrons donc pas dans la presente note qui a pour objet de faire le point, dans quelques domaines caracteristiques, qui nous ont paru les plus susceptibles d'interesser les specialistes etrangers, des resultats obtenus et des experiences faites au cours des deux annees et demi de fonctionnement du reacteur qui ont suivi sa divergence, le 7 janvier 1956. (auteur)

  13. Practical guide to dosimetry as applied in the research reactors of the Saclay and Grenoble nuclear research centers; Guide pratique de la dosimetrie mise en oeuvre dans les reacteurs de recherche du C.E.N./G et du C.E.N./S

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1968-07-01

    Since the problems concerning neutron and gamma flux measurements which arise during irradiation experiments in the reactors in the Grenoble and Saclay Centres are of the same type, and since the solutions found are very often adopted in common, we have attempted to describe the methods we use at the present time. A brief description is given of the production of the detectors, the electronic apparatus; the formulae usually used for the interpretation of the measurements are given. A series of technical data cards give the most commonly used detector characteristics. These cards give the physical characteristics of the detectors, their nuclear constants, if any, the most suitable counting methods and the field of application. (authors) [French] Les problemes de mesures de flux de neutrons et de flux gamma qui se posent pour les experiences irradiees dans les reacteurs des Centres de Grenoble et de Saclay etant du meme type et les solutions trouvees, tres souvent adoptees en commun, nous avons cherche a decrire les methodes que nous pratiquons actuellement. On decrit tres brievement la fabrication des detecteurs, l'appareillage electronique; on rappelle les formules usuelles qui servent dans l'interpretation des mesures. Une serie de fiches techniques rassemble les caracteristiques des detecteurs les plus couramment utilises. Ces fiches indiquent les caracteristiques physiques des detecteurs, leurs constantes nucleaires s'il y a lieu, les methodes de comptage les mieux adaptees et le domaine d'utilisation. (auteurs)

  14. Systematic study of the use of electrical fields for improving heat exchange in boiling liquids; Etude systematique de l'utilisation de champs electriques pour l'amelioration des echanges thermiques dans des liquides bouillants

    Energy Technology Data Exchange (ETDEWEB)

    Bochirol, L; Bonjour, E; Lagnier, R; Verdier, J; Weil, L [Commissariat a l' Energie Atomique, Grenoble (France).Centre d' Etudes Nucleaires

    1961-07-01

    We have studied, at the boiling point, for liquids with various electrical properties (hexane, benzene, trichloroethylene, demineralized water, acetone, methyl-ethyl-ketone, etc...) the effect of the application of electric fields on the exchange coefficients and on the maximum dissipative powers before calefaction. We have given the mechanism of the significant improvements obtained (multiplication by a factor of 2 to 10): - in the natural convection zone by showing the role played by the dielectric properties of the liquids under study; - in the zone of nuclear boiling by analysis of the forces acting on the boiling nuclei. Finally we give some experimental results concerning measurements made under pressure until local boiling occurred: they show the possibility of some interesting applications of the method. (author) [French] On a etudie, a l'ebullition, sur des liquides de caracteristiques electriques diverses (hexane, benzene, trichlorethylene, eau demineralisee, acetone, methylethylcetone, etc...) les effets de l'application de champs electriques sur les coefficients d'echanges et les puissances maximales dissipables avant calefaction. On a precise le mecanisme des ameliorations importantes obtenues (multiplication par un facteur 2 a 10): - dans la zone de convection naturelle en mettant en evidence le role des caracteristiques dielectriques des liquides etudies; - dans la zone d'ebullition nucleaire par analyse des forces mises en jeu sur les noyaux d'ebullition. On donne enfin des resultats experimentaux sur des mesures effectuees sous pression jusqu'a l'ebullition locale: ils illustrent des possibilites d'applications interessantes du procede. (auteur)

  15. [Present conceptions of the C.E.A. concerning] the development of fast neutron reactors in France; [Les conceptions actuelles du C.E.A. concernant] la filiere des reacteurs a neutrons rapides en France

    Energy Technology Data Exchange (ETDEWEB)

    Vendryes, G; Gaussens, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Pasquer, R [Electricite de France (EDF), 75 - Paris (France)

    1964-07-01

    . (authors) [French] 1 - Situation des reacteurs a neutrons rapides dans le programme d'energie nucleaire francais. En developpant un programme base sur l'uranium naturel, la France se trouvera dotee d'un stock important de plutonium riche on isotopes superieurs. L'existence de ce plutonium et de l'uranium appauvri provenant des memes reacteurs a pour consequence logique leur emploi dans des reacteurs a neutrons rapides. Justifiee par cet interet a court terme, la mise au point de reacteurs a neutrons rapides repond par ailleurs a une necessite pour l'avenir. 2 - Enonce des caracteristiques d'une centrale a neutrons rapides de 1000 MW el. Nous indiquons les caracteristiques d'une future centrale a neutrons rapides chargee au plutonium et refroidie au sodium. Si incertaines qu'elles soient, elles constituent un guide necessaire a l'orientation de nos travaux. 3 - Etudes effectuees a ce jour: Nous donnons un apercu des etudes souvent tres preliminaires qui ont permis de retenir les caracteristiques citees plus haut. Les principaux domaines techniques abordes sont les suivants: - Neutronique (masses critiques, taux de regeneration, enrichissements, aplatissement du flux de neutrons, coefficients de reactivite, evolution de la reactivite en fonction de l'irradiation), - Dynamique, controle et surete, - Combustible, - Technologie (conception du bloc-pile, des circuits de sodium, des dispositifs pour la manutention des assemblages). Ces etudes techniques se completent de considerations economiques. Le choix de caracteristiques optimales est lie a l'existence de programmes de production d'electricite et, dans ces programmes, a celle des reacteurs a neutrons thermiques producteurs de plutonium. On montre comment il y a lieu de tenir compte de l'existence du plutonium dans ce contexte, et quels sont les mecanismes qui rattachent l'economie de ce plutonium au choix des parametres essentiels des reacteurs surgenerateurs. 4 - Reacteur prototype: On justifie l'interet d'une etape

  16. Leonhard Euler and the mechanics of rigid bodies

    Science.gov (United States)

    Marquina, J. E.; Marquina, M. L.; Marquina, V.; Hernández-Gómez, J. J.

    2017-01-01

    In this work we present the original ideas and the construction of the rigid bodies theory realised by Leonhard Euler between 1738 and 1775. The number of treatises written by Euler on this subject is enormous, including the most notorious Scientia Navalis (1749), Decouverte d’un noveau principe de mecanique (1752), Du mouvement de rotation des corps solides autour d’un axe variable (1765), Theoria motus corporum solidorum seu rigidorum (1765) and Nova methodus motu corporum rigidorum determinandi (1776), in which he developed the ideas of the instantaneous rotation axis, the so-called Euler equations and angles, the components of what is now known as the inertia tensor, the principal axes of inertia, and, finally, the generalisation of the translation and rotation movement equations for any system. Euler, the man who ‘put most of mechanics into its modern form’ (Truesdell 1968 Essays in the History of Mechanics (Berlin: Springer) p 106).

  17. Ergodicité, collage et transport anomal

    Science.gov (United States)

    Leoncini, Xavier; Chandre, Cristel; Ourrad, Ouerdia

    2008-06-01

    We consider the problem of convergence towards spatial ergodic average of the time average of an observable defined for a one and a half degree of freedom Hamiltonian flow with mixed phase space. The analysis is performed by analysing the evolution of the distribution of finite-time averages. An exponent characterising the "speed of convergence" is defined. Results indicate that for the considered mixed case, the rate of convergence goes as t, with α=0.45 while it goes as t when the full phase space is chaotic. Moreover a formula linking this characteristic exponent to the one corresponding to transport properties β is proposed α=1-β/2 and good agreement is found for the considered cases. To cite this article: X. Leoncini et al., C. R. Mecanique 336 (2008).

  18. The welding of magnesium alloy plugs and canning (1960); Soudage de bouchons et gaines en alliages de magnesium (1960)

    Energy Technology Data Exchange (ETDEWEB)

    Thome, P; Bridoux, C [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    The end or lateral welding of Mg-Zr plugs presents no special difficulties in the manufacture of fuel element slugs. The welding parameters were determined from penetrations and from the mechanical resistance. The unavoidable notching effect has received particular attention. It is possible to substitute a Mg-Zr plug without any modification of the optimum welding conditions and the various qualities of the weld. (author) [French] Le soudage en bout ou lateral de bouchon Mg-Zr ne pose pas de difficultes speciales dans la fabrication des cartouches d'elements combustibles. Les parametres de soudage ont ete determines a partir des penetrations et de la resistance mecanique. L'effet d'entaille qui ne peut etre evite a fait l'objet d'une etude particuliere. La substitution d'un bouchon Mg-Zr est possible sans que soient modifiees les conditions optima de soudage et les diverses qualites de la soudure. (auteur)

  19. Preparation and properties of thin films used in activity determinations with a 4 {pi} counter; Preparation et proprietes des films minces utilises dans les determinations d'activite au compteur 4 {pi}

    Energy Technology Data Exchange (ETDEWEB)

    Jannez, M.; Le Gallic, Y.; Thenard, M. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1958-07-01

    Comparative study of various methods of preparing thin films, for use as source holders in the 4 {pi} counter, and of measuring their thickness. Comparative study of various properties: mechanical resistance; heat resistance; ageing; resistance of rhodopas, polystyrene, formvar and cellulose acetate films to the action of various chemical agents. (author) [French] Etude comparee de divers procedes de preparation de films minces, destines a etre utilises comme supports de sources dans le compteur 4 {pi} et de la mesure de leur epaisseur. Etude comparee de diverses proprietes: resistance mecanique; resistance a la chaleur; vieillissement; resistance a l'action de divers agents chimiques de films de rhodopas, polystyrene, formvar et acetate de cellulose. (auteur)

  20. Piping design and analysis: Comparison between the Belgian applications of French and American rules

    International Nuclear Information System (INIS)

    Daoust, P.H.; Geraets, L.H.; Lafaille, J.P.

    1987-01-01

    In the process of a feasibility study of a new nuclear power plant in Belgium, the French and American rules for piping design have been compared. The Belgian method rests on the American nuclear set of rules and uses the ASME code. French rules were initially based on the American rules (1978). Subsequent individual development led to a differentiation of the rules. Presently the mechanical part of the French rules is mainly contained in the RCC-P ('Regles de Conception et de Construction relatives aux Procedes') and the RCC-M ('Regles de Conception et de Construction des Materiels Mecaniques'). This paper compares the piping design rules from a general point of view; examples of applications allow to identify benefits or drawbacks of the use of ASME or RCCM codes. (orig.)

  1. Ablative Rayleigh Taylor instability in the limit of an infinitely large density ratio

    Science.gov (United States)

    Clavin, Paul; Almarcha, Christophe

    2005-05-01

    The instability of ablation fronts strongly accelerated toward the dense medium under the conditions of inertial confinement fusion (ICF) is addressed in the limit of an infinitely large density ratio. The analysis serves to demonstrate that the flow is irrotational to first order, reducing the nonlinear analysis to solve a two-potential flows problem. Vorticity appears at the following orders in the perturbation analysis. This result simplifies greatly the analysis. The possibility for using boundary integral methods opens new perspectives in the nonlinear theory of the ablative RT instability in ICF. A few examples are given at the end of the Note. To cite this article: P. Clavin, C. Almarcha, C. R. Mecanique 333 (2005).

  2. Material movement of medium surrounding an underground nuclear explosion; Mouvement materiel du milieu environnant une explosion nucleaire souterraine

    Energy Technology Data Exchange (ETDEWEB)

    Guerrini, C; Garnier, J L [Commissariat a l' Energie Atomique, Bruyeres-le-Chatel (France). Centre d' Etudes

    1969-07-01

    The results of measurements of the mechanical effects in the, intermediate zone around underground nuclear explosions in Sahara granite are presented. After a description of the main characteristics of the equipment used, the laws drawn up using experimental results for the acceleration, the velocity, and the material displacement are presented. These laws are compared to those published in other countries for nuclear tests in granite, in tuff and in alluvial deposits. (authors) [French] Les resultats de mesures d'effets mecaniques en zone intermediaire autour d'essais nucleaires souterrains dans le granite du Sahara sont exposes. Apres avoir decrit, dans leurs grandes lignes, les materiels utilises, on presente les lois etablies avec les resultats experimentaux pour l'acceleration, la vitesse et le deplacement materiel. Ces lois sont comparees a celles publiees a l'etranger pour des essais nucleaires dans le granite, le tuf et les alluvions. (auteur)

  3. On the dual variable of the Cauchy stress tensor in isotropic finite hyperelasticity

    Science.gov (United States)

    Vallée, Claude; Fortuné, Danielle; Lerintiu, Camelia

    2008-11-01

    Elastic materials are governed by a constitutive law relating the second Piola-Kirchhoff stress tensor Σ and the right Cauchy-Green strain tensor C=FF. Isotropic elastic materials are the special cases for which the Cauchy stress tensor σ depends solely on the left Cauchy-Green strain tensor B=FF. In this Note we revisit the following property of isotropic hyperelastic materials: if the constitutive law relating Σ and C is derivable from a potential ϕ, then σ and lnB are related by a constitutive law derived from the compound potential ϕ○exp. We give a new and concise proof which is based on an explicit integral formula expressing the derivative of the exponential of a tensor. To cite this article: C. Vallée et al., C. R. Mecanique 336 (2008).

  4. The leakage problem in vacuum system. Realization of a mass spectrometer detecting leaks; Le probleme des fuites en technique du vide. Realisation d'un spectrometre de masse detecteur de fuite

    Energy Technology Data Exchange (ETDEWEB)

    Geller, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1954-11-15

    In the first part of this paper we consider the problem of leaks in vacuum systems, and their detection. We consider in particular the method of detection by means of a helium spectrometer. The second part deals with the experimental set p. The analyser and the ion source have been studied in great detail, and we have also discussed the technological and mechanical aspects of the apparatus and its performances. (author) [French] Dans la premiere partie de ce travail, nous traitons le probleme des fuites en technique du vide et leur detection en general. La methode de detection par spectrometre a helium y est envisagee plus particulierement. La deuxieme partie de l'article est consacree a la realisation du spectrometre. Le tube analyseur et la source d'ions y sont etudies en detail. Nous exposons de meme les conceptions technologiques et mecaniques de l'appareil ainsi que ses performances. (auteur)

  5. Qui sera le nouvel Einstein ? Vers une nouvelle theorie de la gravitation

    Science.gov (United States)

    Bonnet-Bidaud, J. M.

    1999-10-01

    Un debat de plus d'un siecle a resurgi ces toutes dernieres annees avec une vigueur nouvelle. L'enjeu ? Mettre fin, ni plus ni moins, a l'une des contradictions les plus inouies de la physique fondamentale, en reconciliant mecanique quantique et relativite generale. En effet, a l'heure ou la gravitation semble enfin sur le point de fusionner avec les trois autres forces de la nature. il est certain que la relativite d'Einstein doit etre bientot remplacer par une autre theorie... Reste quye tous les physiciens sont loin de s'accorder sur la marche a suivree. Gravitation quantique, relativite d'echelle, supersymetrie, les candidates ne manquent pas.

  6. Fuel rod computations. The COMETHE code in its CEA version

    International Nuclear Information System (INIS)

    Lenepveu, Dominique.

    1976-01-01

    The COMETHE code (COde d'evolution MEcanique et THermique) is intended for computing the irradiation behavior of water reactor fuel pins. It is concerned with steadily operated cylindrical pins, containing fuel pellet stacks (UO 2 or PuO 2 ). The pin consists in five different axial zones: two expansion chambers, two blankets, and a central core that may be divided into several stacks parted by plugs. As far as computation is concerned, the pin is divided into slices (maximum 15) in turn divided into rings (maximum 50). Information are obtained for each slice: the radial temperature distribution, heat transfer coefficients, thermal flux at the pin surface, changes in geometry according to temperature conditions, and specific burn-up. The physical models involved take account for: heat transfer, fission gas release, fuel expansion, and creep of the can. Results computed with COMETHE are compared with those from ELP and EPEL irradiation experiments [fr

  7. Piping design and analysis: comparison between the Belgian applications of French and American rules

    International Nuclear Information System (INIS)

    Daoust, Ph.; Geraets, L.H.; Lafaille, J.P.

    1989-01-01

    In the process of a feasibility study of a new nuclear power plant in Belgium, the French and American rules for piping design have been compared. The Belgian method rests on the American nuclear set of rules and uses the ASME code. French rules were initially based on the American rules (1978). Subsequent individual development led to a differentiation of the rules. Presently, the mechanical part of the French rules is mainly contained in the RCCP ('Regles de Conception et de Construction relatives aux Procedes') and the RCCM ('Regles de Conception et de Construction des materiels Mecaniques'). This paper compares the piping design rules from a general point of view; examples of applications allow benefits or drawbacks of the use of ASME or RCCM codes to identified. (author)

  8. Preparation and properties of thin films used in activity determinations with a 4 {pi} counter; Preparation et proprietes des films minces utilises dans les determinations d'activite au compteur 4 {pi}

    Energy Technology Data Exchange (ETDEWEB)

    Jannez, M; Le Gallic, Y; Thenard, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1958-07-01

    Comparative study of various methods of preparing thin films, for use as source holders in the 4 {pi} counter, and of measuring their thickness. Comparative study of various properties: mechanical resistance; heat resistance; ageing; resistance of rhodopas, polystyrene, formvar and cellulose acetate films to the action of various chemical agents. (author) [French] Etude comparee de divers procedes de preparation de films minces, destines a etre utilises comme supports de sources dans le compteur 4 {pi} et de la mesure de leur epaisseur. Etude comparee de diverses proprietes: resistance mecanique; resistance a la chaleur; vieillissement; resistance a l'action de divers agents chimiques de films de rhodopas, polystyrene, formvar et acetate de cellulose. (auteur)

  9. Biological applications of the Moessbauer effect; Applications de l'effet Mossbauer a la biologie

    Energy Technology Data Exchange (ETDEWEB)

    Boulay, P [CEA Bruyeres-le-Chatel, 91 (France)

    1968-12-01

    The applications of Moessbauer spectrometry in the fields of physics and chemistry have been increasing steadily since its discovery in 1958. Attempts have been made to find applications in biology. Two possibilities of investigation exist in this field: the study of mechanical or vibrational movements in certain animal organs, and the determination of the organic molecular structure in a biological context. An example is given of each of these possibilities. (author) [French] Les applications de la spectrometrie Mossbauer dans le domaine de la physique et de la chimie n'ont cesse de progresser depuis sa decouverte en 1958. Des essais d'application a la biologie ont ete entrepris. Dans ce domaine il existe deux possibilites d'investigation: l'etude des mouvements mecaniques ou vibratoires de certaines organes d'animaux, et la determination de la structure moleculaire organique a destinee biologique. Un exemple est donne de chacune de ces possibilites. (auteur)

  10. Un algorithme efficace d'intégration plastique pour un matériau obéissant au critère anisotrope de Hill

    Science.gov (United States)

    Titeux, Isabelle; Li, Yuming M.; Debray, Karl; Guo, Ying-Qiao

    2004-11-01

    This Note deals with an efficient algorithm to carry out the plastic integration and compute the stresses due to large strains for materials satisfying the Hill's anisotropic yield criterion. The classical algorithm of plastic integration such as 'Return Mapping Method' is largely used for nonlinear analyses of structures and numerical simulations of forming processes, but it requires an iterative schema and may have convergence problems. A new direct algorithm based on a scalar method is developed which allows us to directly obtain the plastic multiplier without an iteration procedure; thus the computation time is largely reduced and the numerical problems are avoided. To cite this article: I. Titeux et al., C. R. Mecanique 332 (2004).

  11. Sur le flambage plastique de l'éprouvette cruciformeAbout the plastic buckling of the cruciform column

    Science.gov (United States)

    Cimetière, Alain; Léger, Alain; Potier-Ferry, Michel

    2004-01-01

    We build a rate potential through the introduction of several behavior assumptions, of which we discuss the physical meaning. Inserted into the quasi-static equations, this potential allows us to revisit the generic problem of the plastic buckling of the cruciform column. We get an interval on the parameter axis of which any point is a bifurcation point. This result is qualitatively interesting from the point of view of spectral analysis, as the existence of such a continuum was up to now related to discontinuities in the constitutive law, while everything is very smooth in the present case. To cite this article: A. Cimetière et al., C. R. Mecanique 332 (2004).

  12. Résistance d'un composite à renforts rigides : le cas d'une matrice de Drucker Prager avec règle d'écoulement plastique non associée

    Science.gov (United States)

    Dormieux, Luc; Barthélémy, Jean-François; Maghous, Samir

    2006-02-01

    A rigid plastic behavior characterized by a failure criterion of the Drucker-Prager type and a non associated flow rule is considered. The latter can be viewed formally as the limit of a sequence of viscous behaviors with isotropic prestress. The limit states of a composite made up of such a material reinforced by rigid inclusions are then determined. The latter lie on a Drucker-Prager cone which friction coefficient is greater than that of the matrix and depends on the characteristics of the strength and of the flow rule of the matrix, as well as on the volume fraction of the inclusions. To cite this article: L. Dormieux et al., C. R. Mecanique 334 (2006).

  13. The use tri-n-butyl phosphate in plutonium extraction. Radiolysis and recycling of the solvent (1963); Le phosphate de tri-n-butyle dans l'extraction du plutonium. Radiolyse et recyclage du solvant (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Isaac, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1963-07-01

    The work concerns the radiolysis and recycling of tri-n-butyl phosphate used as extraction solvent for plutonium. The radiolysis is studied on an industrial solvent using a cobalt 60 source. Figures are given for the yield of the mono- and di-butyl-phosphoric acids formed from the dry and water-saturated solvents and the influence of nitric acid on the formation of dibutyl-phosphoric acid is indicated. The recycling treatment of the solvent is reconsidered with a view to lowering the residual contamination due to fission products. The tests carried out on a solvent from the plutonium extraction plant at Marcoule show the efficiency of the sodium carbonate treatment. Of all the products studied, only caustic soda led to a better decontamination than sodium carbonate; in all cases however, the elimination of ruthenium is always incomplete. (author) [French] L'etude porte sur la radiolyse et le recyclage du phosphate de tri-n-butyle utilise comme solvant d'extraction du plutonium. La radiolyse est etudiee sur un solvant industriel a l'aide d'une source de cobalt 60. On donne les rendements de formation des acides mono- et dlbutylphosphoriques a partir de solvants secs et satures d'eau, et on montre l'influence de l'acide nitrique sur la formation de l'acide dibutylphosphorique. Le traitement de recyclage du solvant est repris en vue d'abaisser la contamination residuelle en produits de fission. Les essais, effectues sur un solvant provenant de l'usine d'extraction du plutonium de Marcoule, montrent l'efficacite du traitement au carbonate de sodium. De tous les reactifs etudies, seule la soude a donne une decontamination superieure au carbonate de sodium; mais dans tous les cas, l'elimination du ruthenium est toujours incomplete. (auteur)

  14. Diagnostic imaging in child abuse; Bildgebende Diagnostik der Kindesmisshandlung

    Energy Technology Data Exchange (ETDEWEB)

    Stoever, B. [Charite, Campus Virchow-Klinikum, Universitaetsmedizin Berlin, Abteilung Paediatrische Radiologie, CC6, Diagnostische und interventionelle Radiologie und Nuklearmedizin, Berlin (Germany)

    2007-11-15

    -Verletzung prognostisch bedeutsam. Initial wird bei diesem Verdacht die CT eingesetzt, um Blutung und Oedem darzustellen, im Verlauf werden mittels MRT Blutungsreste sowie residuelle parenchymatoese Laesionen erfasst. Alle Befunde sind auf ihre Differenzialdiagnosen hin zu pruefen, bevor der Misshandlungsverdacht geaeussert wird. (orig.)

  15. Sampling system for fast single pulses; Realisation d'un dispositif d'echantillonnage d'un signal bref unique

    Energy Technology Data Exchange (ETDEWEB)

    Zenatti, D [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1969-07-01

    Development of a device for the enlargement of the domain of application of classical oscilloscopes to the observation of fast single pulses by application of the sampling principle. Its principal characteristics are: Bandwidth of 700 MHz; Maximum sensibility of 50 mV; Maximum amplitude of input signal of {+-} 1 V; Number of samples of 16; Samples separation of 0,2 ns. (author) [French] Realisation d'un dispositif permettant d'elargir le domaine d'utilisation des oscilloscopes classiques en appliquant le principe de l'echantillonnage a l'observation d'un signal bref unique. Les principales caracteristiques sont les suivantes: Bande passante de 700 MHz; Sensibilite maximale de 50 mV; Amplitude maximale du signal a echantillonner de {+-} 1 V; Nombre de points d'echantillonnage de 16; Pas d'echantillonnage de 0,2 ns. (auteur)

  16. Contribution to the study of {beta} disintegration and of nuclear structure using experiments on certain {beta}-{gamma} cascades: 198{sub Au}, 86{sub Rb}, 170{sub Tm}; Contribution a l'etude de la desintegration beta et a l'etude de la structure nucleaire a l'aide d'experiences sur certaines cascades beta-gamma: 198{sub Au}, 86{sub Rb}, 170{sub Tm}

    Energy Technology Data Exchange (ETDEWEB)

    Lachkar, J. [Commissariat a l' Energie Atomique, Bruyeres-le-Chatel (France). Centre d' Etudes; Paris-11 Univ., fabulte des Sciences 91 - Orsay (France)

    1969-07-01

    {beta}{gamma} directional angular correlations and shapes of inner beta spectra leading to the first excited level of the final nucleus enable one to determine the nuclear matrix elements typical of the {beta} transition. In the three observed first forbidden cases: {sup 170}Tm, {sup 86}Rb, {sup 198}Au, these matrix elements do not confirm the independent shell model theory. Other hypotheses are then suggested and discussed. (author) [French] Les experiences de correlation angulaire {beta}{gamma} et l'etude du spectre {beta} conduisant au premier niveau excite du noyau final permettent de determiner les elements de matrices nucleaires caracteristiques de cette transition. Dans les trois cas etudies (transitions une fois interdites): {sup 170}Tm, {sup 86}Rb, {sup 198}Au, ces elements de matrices ne peuvent etre retrouves a l'aide du modele en couches et a particules independantes. D'autres hypotheses sont alors emises et discutees. (auteur)

  17. Applications of Qualitative Microanalysis to the Determination of Secondary Species Associated with Uranium; Application de la microanalyse qualitative a la determination des especes secondaires d'uranium

    Energy Technology Data Exchange (ETDEWEB)

    Agrinier, H

    1959-02-01

    Microanalytical techniques are described which allow rapid determinations of secondary species associated with uranium. They consist in exposing the constituent elements of the ores by means of characteristic microchemical reactions. Because of their rapidity and the small amount of apparatus needed, these techniques can be used either in the field or in the laboratory. (author) [French] Les techniques de microanalyse decrites dans cet ouvrage permettent la determination rapide des especes secondaires d'uranium. Elles consistent a mettre en evidence les elements constitutifs des mineraux par des reactions microchimiques caracteristiques. En raison de leur rapidite et du peu de materiel qu'elles necessitent, ces techniques peuvent etre utilisees aussi bien sur le terrain qu'au laboratoire. (auteur)

  18. Description of the french graphite reactor and of the experiments performed in 1956; Presentation du premier reacteur a graphite francais et des experiences effectuees en 1956

    Energy Technology Data Exchange (ETDEWEB)

    Bussac, J; Leduc, C; Zaleski, C P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1957-07-01

    This paper is an introduction to the experiments performed on the G1 reactor, experiments fully described in the papers following (670 'B to P'). The main results are given together with some comments. The neutronic parameters of the core, a description of the most important structures, and a few words of the tests leading to normal operation of the reactor under load complete our survey. (author) [French] Ce rapport presente les experiences qui furent faites sur le reacteur G1 et dont la description en detail fait l'objet des rapports suivants (670 'B a P'). Les principaux resultats sont fournis ici et commentes. On trouvera en outre les caracteristiques neutroniques du coeur actif de la pile, une description des principales installations et une mention des essais qui ont conduit au fonctionnement normal du reacteur en puissance. (auteur)

  19. The construction of standardised equipment expressly adapted to the different methods of radiation control; Realisation de materiel standardise specialement adapte aux divers modes de controle des radiations

    Energy Technology Data Exchange (ETDEWEB)

    Savouyaud, J; Menoux, A [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    The authors show what general characteristics must have equipment designed for radiation control. This equipment must make possible the measurement of doses corresponding to 1/10 of the maximum permissible limit. It should be designed for a specific purpose, and finally it should be independent as far as possible. The authors review the different types of control which it is necessary to effect. (author) [French] Les auteurs indiquent quelles doivent etre les caracteristiques generales du materiel de controle des radiations. Ce materiel doit permettre l'appreciation de mesures correspondant au 1/10{sup e} des limites maximales admissibles. Il devrait etre concu pour une fonction determinee, enfin, il doit etre dans la mesure du possible, autonome. Les auteurs passent en revue les differents types de controle qu'il est necessaire de couvrir. (auteur)

  20. Uranium deposits in the Nord-Limousin; Les gites d'uranium du Nord-Limousin

    Energy Technology Data Exchange (ETDEWEB)

    Sarcia, J A; Sarcia, J A [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1958-07-01

    The authors briefly consider the region in its geographical and geological setting. They describe the main petrographic, metallogenic and tectonic characteristics of the sector investigated by the Atomic Energy Commission since 1947, stressing the form of uraniferous mineral deposits. This short account is intended as a general presentation of the detailed studies which will follow, of which that dealing with the mine Henriette is the first to be published. (author) [French] Les auteurs replacent rapidement la region dans son cadre geographique et geologique. Ils decrivent les principales caracteristiques petrographiques, metallogeniques et tectoniques du secteur etudie par le Commissariat a I'Energie atomique depuis 1947, en insistant sur le mode de gisement des mineralisations uraniferes. Ces quelques pages sont destinees a la presentation generale des etudes de detail qui suivront, dont celle qui concerne la Mine Henriette est la premiere publiee. (auteur)

  1. Half-life distribution table of radioactive nuclei; Table de distribution des periodes des noyaux radioactifs

    Energy Technology Data Exchange (ETDEWEB)

    Gugenberger, P [Commissariat a l' Energie Atomique, Saclay(France). Centre d' Etudes Nucleaires

    1954-07-01

    This table allows to identify an element if its period is known. Data for this table were taken from the half-life values adopted by Hollander, PERLMAN and SEABORG (Rev. mod. Phys., 1953, 22 number 2). Moreover for each nucleus, the mass number, the charge number and the type of decay are given in the table. (author) [French] Cette table permet l'identification d'un element dont la periode est connue. Elle a ete etablie en utilisant les valeurs des periodes donnees par HOLLANDER, PERLMAN et SEABORG dans Rev. mod. Phys., 1953, 25 numero 2. On y trouve en outre, pour chaque nuclide, les caracteristiques suivantes: Z, A, modes de desintegration. (auteur)

  2. Some results concerning the external photoelectric effect and secondary emission; Quelques resultats sur l'effet photoelectrique externe et l'emission secondaire

    Energy Technology Data Exchange (ETDEWEB)

    Lenouvel, F [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Ecole normale superieure, 75 - Paris (France)

    1967-01-01

    The characteristics and limiting possibilities of the various constituent parts of a photoelectric detector are considered. Two methods for illuminating the cathode are described and discussed. The few scattered results concerning the maximum output of cathodes and dynodes are collected together and a tentative explanation is put forward. A comparison is made of three methods for measuring very low light fluxes. (author) [French] Nous degageons les caracteristiques et les possibilites limites des divers elements constitutifs d'un detecteur photoelectrique. Deux solutions d'illumination de la cathode sont decrites et discutees. Les quelques resultats epars sur la limite de debit des cathodes et des dynodes sont rassembles et une interpretation provisoire est esquissee. Trois moyens de mesure des tres faibles flux lumineux sont compares. (auteur)

  3. Stabilisation of photo-multiplying gain; Stabilisation du gain des pbotomultiplicateurs

    Energy Technology Data Exchange (ETDEWEB)

    Tretiakoff, O; Bailly du Bois, B [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1956-07-01

    The use of photomultiplier tubes in experimental physics is thwarted by their high responsiveness to changes in the feeding tension. Their use can be extended a great deal by a simple efficient stabilizing device which allows them to work in the same way as Geiger-Mueller tubes without losing the advantageous characteristics of photomultiplier tubes. (author) [French] L'utilisation des tubes photomultiplicateurs en physique experimentale se heurte a l'obstacle que constitue leur extreme sensibilite aux variations de la tension d'alimentation. Un systeme de stabilisation simple et efficace, permettant d'apparenter leurs caracteristiques a celles des compteurs Geiger-Muller tout en conservant les avantages propres aux tubes photomultiplicateurs, peut elargir considerablement leur domaine d'emploi. (auteur)

  4. Some results on the fluorescence of gases excited by high-energy charged particles; Quelques resultats concernant la fluorescence de gaz excites par des particules chargees de grande energie

    Energy Technology Data Exchange (ETDEWEB)

    Koch, L; Lesureur, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1958-07-01

    The essential characteristics of rare gases for use as scintillators are as follows: a very brief period of luminescence, generally less than 10{sup -8} s; a linear response as a function of the energy lost by the nuclear particle in the gas, even in the case of strongly ionising particles (fission fragments). In the gaseous or condensed state therefore, they are of great interest in nuclear physics. (author) [French] Les caracteristiques essentielles des gaz rares en tant que scintillateurs sont: une duree de luminescence tres breve, inferieure a 10{sup -8} s en general; une reponse lineaire en fonction de l'energie perdue par la particule nucleaire dans le gaz, meme dans le cas de particules fortement ionisantes (fragments de fission). A l'etat gazeux ou condense, ils presentent donc un grand interet en physique nucleaire. (auteur)

  5. Some notes concerning the fourier transformation of auto-correlation functions; Quelques notes sur la transformee de fourier des fonctions d'autocorrelation

    Energy Technology Data Exchange (ETDEWEB)

    Froelicher, B; Dalfes, A [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1968-07-01

    A study is made of the passage of the auto-correlation function to the frequency spectrum by a numerical Fourier transformation. Two principal characteristics of auto-correlation functions, the time between two points and the total time, are related to two oscillations which appear in the frequency spectrum and which deform it. Various methods are proposed for reducing the effect of these two parasitic oscillations and for re-obtaining the real spectrum. (authors) [French] On etudie le passage de la fonction d'autocorrelation au spectre de frequence par transformee de Fourier numerique. Deux caracteristiques principales des fonctions d'autocorrelation, la duree entre points et la duree totale sont reliees a deux oscillations qui apparaissent dans le spectre de frequence et le deforment. Diverses methodes sont proposees pour reduire l'effet de ces deux oscillations parasites, et retrouver le spectre reel. (auteurs)

  6. Construction of a differential thermal analysis installation; Realisation d'une installation d'analyse thermique differentielle

    Energy Technology Data Exchange (ETDEWEB)

    Branche, G; Chantret, F [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1959-07-01

    The authors are indicating the characteristics of a D.T.A. installation they built. Experimental rooms, ovens, thermal regulation, recording methods are thoroughly described, with outlining of the requirements to obtain a high sensitivity. Numerous D.T.A. curves relating to argillaceous substances, bituminous shales, and uraniferous compounds are given. (author) [French] Les auteurs donnent les caracteristiques de l'installation d'Analyse Thermique Differentielle qu'ils ont construits. Ils decrivent en detail les chambres d'experiences, les fours, la regulation thermique, l'enregistrement, en insistant sur les conditions necessaires pour obtenir une sensibilite elevee. Ils donnent de nombreuses courbes differentielles relatives des produits argileux, des schistes bitumineux et des composes uraniferes. (auteur)

  7. Study of the tributyl phosphate - 30% dodecane solvent; Etude du solvant phosphate tributylique - 30 % dodecane

    Energy Technology Data Exchange (ETDEWEB)

    Leroy, P [Commissariat a l' Energie Atomique, Fontenay-aux-Roses. Centre d' Etudes Nucleaires, 92 (France)

    1967-07-01

    This study, originating mainly from a literature survey, gives the principal chemical and physical features of the tributyl-phosphate (TBP) agent diluted at 30 volumes per cent in dodecane. The mixture is a very commonly used extractant in nuclear fuel processing. In this paper, the main following points are reported: -) the components (TBP and diluents) -) the TBP-diluents systems (non-loaded), -) the TBP-diluents-water systems, -) TBP-diluents-water-nitric acid systems, and -) industrial solvents. (author) [French] Cette etude, d'origine bibliographique, regroupe les caracteristiques physico-chimiques essentielles du phosphate tributylique (TBP) dilue a 30% en volume dans du dodecane. Ce melange constitue un agent d'extraction tres utilise dans le traitement des combustibles nucleaires. Les principaux points traites sont les suivants: -) les constituants (TBP et diluants), -) les systemes TBP-diluants non charges, -) les systemes TBP-diluants-eau, -) les systemes TBP-diluants-eau-acide nitrique, et -) les solvants industriels. (auteur)

  8. Decades with four double triodes; Decades a quatre doubles triodes

    Energy Technology Data Exchange (ETDEWEB)

    Wahl, R [Commissariat a l' Energie Atomique, Lab. du Fort de Chatillon, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1952-07-01

    Decades with four double triodes The described decade consists of four double triodes and four crystals germanium; which has the following characteristics: - Attack in negative impulses. - Sensitivity 12 volts {+-} 40 % for signals of 1 {mu}s about. - Time of resolution 2,5 {mu}s. - Voltage 250 v {+-} 40 %. - heating 6,3 v {+-} 40 %. - Tolerance on the values of the elements of installation 10%. (author) [French] La decade decrite comprend quatre doubles triodes et quatre cristaux germanium; elle a les caracteristiques suivantes: - Attaque en impulsions negatives. - Sensiblite 12 volts {+-} 40 % pour des signaux de 1 {mu}s environ. - Temps de resolution 2,5 {mu}s. - Alimentation 250 v {+-} 40 %. - Chauffage 6,3 v {+-} 40 %. - Tolerance sur les valeurs des elements de montage l0 %. (auteur)

  9. Reactivity of non-stoichiometric black alumina; Reactivite des alumines noires non stoechiometriques

    Energy Technology Data Exchange (ETDEWEB)

    Arghiropoulos, B; Elston, J; Hilaire, P; Juillet, F; Teichner, S J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; [Lyon-1 Univ., 69 (France)

    1960-07-01

    Oxides such as alumina, when divided or poorly crystallized, show enhanced physico-chemical properties with respect to those of non-divided crystals of the same solids. A stoichiometric difference may even be produced in the alumina, which brings about a new modification of its properties. However its characteristics of hydrogen chemisorption or of catalytic activity in ethylene hydrogenation do not appear to depend on the stoichiometric difference. (author) [French] Les oxydes, comme l'alumine, divises ou mal cristallises, presentent des proprietes physico-chimiques exaltees par rapport a celles des memes solides en cristaux non divises. Un ecart a la stoechiometrie peut meme etre produit dans l'alumine, ce qui entraine une nouvelle modification de ses proprietes. Toutefois ses caracteristiques de chimisorption d'hydrogene ou d'activite catalytique d'hydrogenation d'ethylene ne semblent pas dependre de l'ecart a la stoechiometrie. (auteur)

  10. Intense pulsed sources of ions and electrons produced by lasers; Sources pulsees intenses d'ions et d'electrons produites par laser

    Energy Technology Data Exchange (ETDEWEB)

    Bourrabier, G [Centre de Recherche de la C.S.F., Corbeville (France); Consoli, T; Slama, L [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1966-11-01

    We describe a device for the acceleration of the plasma burst produced by focusing a laser beam into a metal target. We extract the electrons and the ions from the plasma. The maximum current is around 2000 amperes during few microseconds. The study of the effect of the kind of the target on the characteristics of the current shows the great importance of the initial conditions that is the ionisation potential of the target and the energy laser. (authors) [French] On decrit un dispositif destine a accelerer la bouffee de plasma produite par focalisation d'un faisceau laser sur une cible solide. On extrait du plasma les electrons et les ions. Le courant maximum atteint pres de 2000 amperes pendant quelques microsecondes. L'etude de l'effet de la nature de la cible sur les caracteristiques du courant collecte, met en evidence l'importance des conditions initiales (potentiel d'ionisation de la cible, energie du laser). (auteurs)

  11. Isotope Analysis of Uranium by Interferometry; Analyse isotopique de l'uranium par interferometrie

    Energy Technology Data Exchange (ETDEWEB)

    Leicknam, J P [Commissariat a l' Energie Atomique. Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France)

    1962-07-01

    Among the optical methods which may be used to make isotopic measurements of {sup 235}U interferometry gives promising results. An apparatus is described which has a photomultiplier as receiver; the source must therefore have characteristics (intensity, stability, fineness of emitted rays) which have led to the use of electrode-less discharge tubes whose methods of production and excitation are given. An example of calibration is given. (author) [French] Parmi les methodes optiques permettant le dosage isotopique de l'uranium 235, l'interferometrie est une technique qui donne des resultats prometteurs. On decrit ici un appareil ayant un photo-multiplicateur comme recepteur; la source doit donc avoir des caracteristiques (intensite, stabilite, finesse des raies emises) qui ont conduit a utiliser des tubes a decharge sans electrode dont on indique la fabrication et le mode d'excitation. Un exemple d'etalonnage est enfin donne. (auteur)

  12. The fast breeder reactor Rapsodie (1962); Le reacteur rapide surregenerateur rapsodie (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Vautrey, L; Zaleski, C P [Commissariat a l' Energie Atomique, Cadarache (France). Centre d' Etudes Nucleaires

    1962-07-01

    In this report, the authors describe the Rapsodie project, the French fast breeder reactor, as it stands at construction actual start-up. The paper provides informations about: the principal neutronic and thermal characteristics, the reactor and its cooling circuits, the main handling devices of radioactive or contaminated assemblies, the principles and means governing reactor operation, the purposes and locations of miscellaneous buildings. Rapsodie is expected to be critical by 1964. (authors) [French] Dans ce rapport, les auteurs font le point du projet RAPSODIE (reacteur francais surregenerateur a neutrons rapides), au moment du debut effectif de sa construction. On y trouvera decrits: les principales caracteristiques neutroniques et thermiques, le bloc pile et les circuits de refroidissement, les principaux moyens de manutention des ensembles actifs ou contamines, les principes et les moyens qui regissent la conduite du reacteur, les fonctions et l'implantation des divers batiments. La divergence de RAPSODIE est prevue pour 1964. (auteurs)

  13. LES PROBLÈMES AGRICOLE DE LA GUINÉE

    Directory of Open Access Journals (Sweden)

    Ousmane Kobele-Keita

    2010-01-01

    Full Text Available Dans le présent article il est indiqué les caracteristiques agricoles de la République de Guinée comme facteur déterminant de son économie. L’analyse concerne les conditions pedo-climatiques de la Guinée, sa situation géographique, demographique, économique, mais aussi les aspects culturels et juridiques de la vie paysanne de ce pays de l’Afrique de l’Ouest. L’accent a été mis également sur les difficultés que rencontre l’agriculture guinéenne tout en soulignant les voies et moyens á suivre pour développer cette agriculture.

  14. Sampling system for fast single pulses; Realisation d'un dispositif d'echantillonnage d'un signal bref unique

    Energy Technology Data Exchange (ETDEWEB)

    Zenatti, D. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1969-07-01

    Development of a device for the enlargement of the domain of application of classical oscilloscopes to the observation of fast single pulses by application of the sampling principle. Its principal characteristics are: Bandwidth of 700 MHz; Maximum sensibility of 50 mV; Maximum amplitude of input signal of {+-} 1 V; Number of samples of 16; Samples separation of 0,2 ns. (author) [French] Realisation d'un dispositif permettant d'elargir le domaine d'utilisation des oscilloscopes classiques en appliquant le principe de l'echantillonnage a l'observation d'un signal bref unique. Les principales caracteristiques sont les suivantes: Bande passante de 700 MHz; Sensibilite maximale de 50 mV; Amplitude maximale du signal a echantillonner de {+-} 1 V; Nombre de points d'echantillonnage de 16; Pas d'echantillonnage de 0,2 ns. (auteur)

  15. Neutron Spectrometry Work at the CNEN; La spectrometrie neutronique au CNEN; Raboty po nejtronnoj spektrometrii v nkyaeh; Trabajos de espectrometria neutronica realizados en el CNEN

    Energy Technology Data Exchange (ETDEWEB)

    Caglioti, G; Ascarelli, P [Comitato Nazionale per L' energia Nucleare Euratom, G. C. R. Ispra, Varese (Italy)

    1963-01-15

    In this communication the main features of the triple axis spectrometer recently installed at the Ispra-1 reactor are presented. Preliminary results in the quasi elastic angular distribution of 1.4A neutrons scattered in liquid bromine are shown and briefly discussed. (author) [French] Dans ce memoire, l'auteur decrit les principales caracteristiques du spectrometre triaxial installe recemment au reacteur Ispra-1. Il donne et examine brievement les resultats preliminaires des experiences sur la distribution angulaire quasi elastique de neutrons de 1.4A a diffuses dans du brome liquide. (author) [Spanish] La memoria describe las principales caracteristicas del espectrometro triaxial recientemente instalado en el reactor lspra-1. Asimismo, expone brevemente los resultados iniciales de las determinaciones de distribucion angular de neutrones de 1,4 A dispersados en forma cuasi elastica por bromo liquido. (author)

  16. Half-life distribution table of radioactive nuclei; Table de distribution des periodes des noyaux radioactifs

    Energy Technology Data Exchange (ETDEWEB)

    Gugenberger, P. [Commissariat a l' Energie Atomique, Saclay(France). Centre d' Etudes Nucleaires

    1954-07-01

    This table allows to identify an element if its period is known. Data for this table were taken from the half-life values adopted by Hollander, PERLMAN and SEABORG (Rev. mod. Phys., 1953, 22 number 2). Moreover for each nucleus, the mass number, the charge number and the type of decay are given in the table. (author) [French] Cette table permet l'identification d'un element dont la periode est connue. Elle a ete etablie en utilisant les valeurs des periodes donnees par HOLLANDER, PERLMAN et SEABORG dans Rev. mod. Phys., 1953, 25 numero 2. On y trouve en outre, pour chaque nuclide, les caracteristiques suivantes: Z, A, modes de desintegration. (auteur)

  17. Contribution to the study of {beta} disintegration and of nuclear structure using experiments on certain {beta}-{gamma} cascades: 198{sub Au}, 86{sub Rb}, 170{sub Tm}; Contribution a l'etude de la desintegration beta et a l'etude de la structure nucleaire a l'aide d'experiences sur certaines cascades beta-gamma: 198{sub Au}, 86{sub Rb}, 170{sub Tm}

    Energy Technology Data Exchange (ETDEWEB)

    Lachkar, J [Commissariat a l' Energie Atomique, Bruyeres-le-Chatel (France). Centre d' Etudes; Paris-11 Univ., fabulte des Sciences 91 - Orsay (France)

    1969-07-01

    {beta}{gamma} directional angular correlations and shapes of inner beta spectra leading to the first excited level of the final nucleus enable one to determine the nuclear matrix elements typical of the {beta} transition. In the three observed first forbidden cases: {sup 170}Tm, {sup 86}Rb, {sup 198}Au, these matrix elements do not confirm the independent shell model theory. Other hypotheses are then suggested and discussed. (author) [French] Les experiences de correlation angulaire {beta}{gamma} et l'etude du spectre {beta} conduisant au premier niveau excite du noyau final permettent de determiner les elements de matrices nucleaires caracteristiques de cette transition. Dans les trois cas etudies (transitions une fois interdites): {sup 170}Tm, {sup 86}Rb, {sup 198}Au, ces elements de matrices ne peuvent etre retrouves a l'aide du modele en couches et a particules independantes. D'autres hypotheses sont alors emises et discutees. (auteur)

  18. Cell for studying electron-adsorbed gas interactions; Cellule d'etudes des interactions electron-gaz adsorbe

    Energy Technology Data Exchange (ETDEWEB)

    Golowacz, H; Degras, D A [Commissariat a l' Energie Atomique, 91 - Saclay (France). Centre d' Etudes Nucleaires, Deptartement de Physique des Plasmas et de la Fusion Controlee, Service de Physique Appliquee, Service de Physique des Interractions Electroniques, Section d' Etude des Interactions Gaz-Solides

    1967-07-01

    The geometry and the technology of a cell used for investigations on electron-adsorbed gas interactions are described. The resonance frequencies of the surface ions which are created by the electron impact on the adsorbed gas are predicted by simplified calculations. The experimental data relative to carbon monoxide and neon are in good agreement with these predictions. (authors) [French] Les caracteristiques geometriques et technologiques generales d'une cellule d'etude des interactions entre un faisceau d'electrons et un gaz adsorbe sont donnees. Un calcul simplifie permet de prevoir les frequences de resonance des ions de surface crees par l'impact des electrons sur le gaz adsorbe. Les donnees experimentales sur l'oxyde de carbone et le neon confirment les previsions du calcul. (auteurs)

  19. Approximation auto-coherente a deux particules, pseudogap et supraconductivite dans le modele de Hubbard attractif

    Science.gov (United States)

    Allen, Steve

    2000-10-01

    Dans cette these nous presentons une nouvelle methode non perturbative pour le calcul des proprietes d'un systeme de fermions. Notre methode generalise l'approximation auto-coherente a deux particules proposee par Vilk et Tremblay pour le modele de Hubbard repulsif. Notre methode peut s'appliquer a l'etude du comportement pre-critique lorsque la symetrie du parametre d'ordre est suffisamment elevee. Nous appliquons la methode au probleme du pseudogap dans le modele de Hubbard attractif. Nos resultats montrent un excellent accord avec les donnees Monte Carlo pour de petits systemes. Nous observons que le regime ou apparait le pseudogap dans le poids spectral a une particule est un regime classique renormalise caracterise par une frequence caracteristique des fluctuations supraconductrices inferieure a la temperature. Une autre caracteristique est la faible densite de superfluide de cette phase demontrant que nous ne sommes pas en presence de paires preformees. Les resultats obtenus semblent montrer que la haute symetrie du parametre d'ordre et la bidimensionalite du systeme etudie elargissent le domaine de temperature pour lequel le regime pseudogap est observe. Nous argumentons que ce resultat est transposable aux supraconducteurs a haute temperature critique ou le pseudogap apparait a des' temperatures beaucoup plus grandes que la temperature critique. La forte symetrie dans ces systemes pourraient etre reliee a la theorie SO(5) de Zhang. En annexe, nous demontrons un resultat tout recent qui permettrait d'assurer l'auto-coherence entre les proprietes a une et a deux particules par l'ajout d'une dynamique au vertex irreductible. Cet ajout laisse entrevoir la possibilite d'etendre la methode au cas d'une forte interaction.

  20. Contribution to the selection of radioactive tracers for hydrogeology; Contribution a la selection de traceurs radioactifs pour l'hydrogeologie

    Energy Technology Data Exchange (ETDEWEB)

    Lallemand, A [Bureau de recherches geologiques et minieres (BRGM), Paris (France); Grison, G [Commission des Communautes europeennes, Brussels (Belgium)

    1970-09-15

    A systematic study was made of a number of anionic and cationic tracers in different terrains with distinct petrographic characteristics, allowance being made for the various physical and chemical parameters of the environment. The behaviour of 12 tracers ({sup 51}Cr, {sup 59}Fe, {sup 45}Ca, {sup 110}Ag, {sup 24}Na, {sup 137}Cs, {sup 3}H, {sup 32}P, {sup 35}S, {sup 14}C, {sup 131}I, {sup 82}Br) was studied in six types of argillaceous rock (illite, vermiculite, interstratified illite-vermiculite, montmorillonite, attapulgite and kaolinite) and three sand types (siliceous, calcareous and dolomitic) in the presence of three types of water (demineralized, sea-water and various spring waters). On the basis of the results obtained from 5000 tests and measurements made during this study it is possible to select the tracer most suited to the characteristics of the terrain and the type of groundwater. (author) [French] Les travaux effectues ont pour objectif l'etude systematique d'un certain nombre de traceurs anioniques et cationiques sur une serie de terrains a caracteristiques petrographiques bien determinees, compte tenu d'un certain nombre de parametres physiques et chimiques du milieu. Le comportement de douze traceurs ({sup 51}Cr, {sup 59}Fe, {sup 45}Ca, {sup 110}Ag, {sup 24}Na, {sup 137}Cs, {sup 3}H, {sup 32}P, {sup 35}S, {sup 14}C, {sup 131}I et {sup 82}Br) a ete etudie dans six roches argileuses (illite, vermiculite, interstratifie illite-vermiculite, montmorillonite, attapulgite, kaolinite) et trois sables (siliceux, calcaire, dolomitique) en presence de trois types d'eau (demineralisee, eau de mer et diverses eaux de source). Les resultats des 5000 essais et mesures effectues au cours de cette etude permettent de selectionner le traceur repondant le mieux aux caracteristiques du terrain et du type d'eau de la nappe. (author)

  1. Contribution to the Selection of Radioactive Tracers for Hydrogeology; Contribution a la Selection de Traceurs Radioactifs pour l'Hydrogeologie

    Energy Technology Data Exchange (ETDEWEB)

    Lallemand, Andree [Bureau de Recherches Geologiques et Minieres (BRGM), Paris (France); Grison, G. [Commission des Communautes Europeennes, Bruxelles (Belgium)

    1970-09-15

    A systematic study was made of a number of anionic and cationic tracers in different terrains with distinct petrographic characteristics, allowance being made for the various physical and chemical parameters of the environment. The behaviour of 12 tracers ({sup 51}Cr, {sup 59}Fe, {sup 45}Ca, {sup 110}Ag, {sup 24}Na, {sup 137}Cs, {sup 3}H, {sup 32}P, {sup 35}S, {sup 14}C, {sup 131}I, {sup 82}Br) was studied in six types of argillaceous rock (illite, vermiculite, interstratified illite-vermiculite, montmorillonite, attapulgite and kaolinite) and three sand types (siliceous, calcareous and dolomitic) in the presence of three types of water (demineralized, sea-water and various spring waters). On the basis of the results obtained from 5000 tests and measurements made during this study it is possible to select the tracer most suited to the characteristics of the terrain and the type of groundwater. (author) [French] Les travaux effectues ont pour objectif l'etude systematique d'un certain nombre de traceurs anioniques et cationiques sur une serie de terrains a caracteristiques petrographiques bien determinees, compte tenu d'un certain nombre de parametres physiques et- chimiques du milieu. Le comportement de douze traceurs ({sup 51}Cr, {sup 59}Fe, {sup 45}Ca, {sup 110}Ag, {sup 24}Na, {sup 137}Cs, {sup 3}H, {sup 32}P, {sup 35}S, {sup 14}C, {sup 131}I et {sup 82}Br) a ete etudie dans six roches argileuses (illite, vermiculite, interstratifie illite-vermiculite, montmorillonite, attapulgite, kaolinite) et trois sables (siliceux, calcaire, dolomitique) en presence de trois types d'eau (demineralisee, eau de mer et diverses eaux de source). Les resultats des 5000 essais et mesures effectues au cours de cette etude permettent de selectionner le traceur repondant le mieux aux caracteristiques du terrain et du type d'eau de la nappe. (author)

  2. Theoretical study and construction of a multichannel {beta} spectrometer with uniform magnetic field; Etude et realisation d'un spectrometre {beta} multivoies a champ magnetique uniforme

    Energy Technology Data Exchange (ETDEWEB)

    Schussler, F [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1965-09-01

    After a brief survey of the interest of a multichannel beta spectrometer for studying decay schemes of short lived nuclides (30 seconds minimum, the theoretically well known characteristics of uniform magnetic field analyser (image of a large source, transmission and resolution) are briefly remembered. In the second part, the apparatus built as a result of these calculations is described. This apparatus allows the determination of beta spectra by simultaneous determination of the beta spectra in coincidence with four gamma rays predetermined in the gamma spectrum of the studied nuclide. Finally, in the last part, the experimental characteristics of the spectrometer (calibration in energy and transmission) and the first measurement of beta spectra ({sup 155}Sm) and of coincidences ({sup 24}Na), are given. (author) [French] Apres avoir brievement souligne l'interet pratique que presente un spectrometre multivoies pour l'etude des schemas de desintegration des corps radioactifs de courtes periodes (30 secondes au maximum), l'auteur effectue un rappel des caracteristiques theoriques bien connues d'un analyseur magnetique a champ uniforme (image d'une source etendue) calcul de la transmission et du pouvoir de resolution. Une deuxieme partie est consacree a la description de l'appareil realise d'apres ces calculs. Cet appareil permet le releve des spectres beta par detection, simultanee de dix groupes d'electrons d'energies differentes; il permet egalement le releve simultane des spectres beta en coincidence avec quatre rayonnements gammas preselectionnes a l'avance dans le spectre gamma du corps etudie. Dans une derniere partie enfin, sont donnees les caracteristiques experimentales du spectrometre (etalonnage en energie et en transmission) ainsi que les premiers resultats des etudes de spectre beta ({sup 155}Sm) et de coincidence ({sup 24}Na). (auteur)

  3. Studies on the gamma-gamma method. Definition of an apparatus for on-the-spot measurement of uranium ore densities; Etudes sur la methode gamma-gamma. Determination d'un appareillage pour la mesure en place de la densite des minerais d'uranium

    Energy Technology Data Exchange (ETDEWEB)

    Czubek, J A [Institut de Recheches Nucleaires, Dept. 6, Cracovie (Poland); Guitton, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1966-07-01

    The work described follows on to the research published in report CEA-R--2720 in march 1965. It includes: - experimental results obtained with a model composed of a constant density material (graphite); - the drawing-up of calibration curves using the similitude principle; - determination of the characteristics of a gamma-gamma probe, together with a discussion. The influence is studied of a certain number of parameters on the shape of the energy spectra of scattered radiation, and of the calibration curves: nature of the radioactive source, diameter of the probe area, source detector distance, geometrical shape of shielding between the source and the detector. An attempt is made to find a mathematical model for the calibration curve, for given conditions. Numerical applications make it possible to establish the optimum technical characteristics for a probe measuring the density with the smallest statistical error. (authors) [French] Les travaux decrits font suite aux etudes presentees dans le rapport CEA-R--2720 de mars 1965. Ils portent sur: - les resultats experimentaux obtenus sur un modele constitue d'un materiau de densite constante (graphite) ; - l'etablissement de courbes d'etalonnage a l'aide du principe de similitude; - la recherche et la discussion des caracteristiques d'une sonde gamma-gamma. L'influence d'un certain nombre de parametres sur la forme des spectres d'energie du rayonnement diffuse et des courbes d'etalonnage est etudiee: nature de la source radioactive, diametre du sondage, distance source-detecteur, forme geometrique du blindage entre la source et le detecteur. Pour des conditions determinees, le modele mathematique de la courbe d'etalonnage est recherche. Des applications numeriques permettent d'etablir les caracteristiques techniques optimales d'une sonde mesurant la densite avec la plus faible erreur statistique. (auteurs)

  4. Theoretical study, and construction, of a spherical electrostatic beta spectrometer; Etude theorique et realisation d'un spectrometre beta electrostatique spherique

    Energy Technology Data Exchange (ETDEWEB)

    Moret, R [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1964-03-15

    After a literature survey showing the importance of an electrostatic spectrometer with spherical electrodes for studying disintegration processes, the theoretical characteristics of such an apparatus are derived (determination of the trajectory equations calculation of the transmission and of the resolving power the case of a point source and of an extended source). The apparatus built as a result of these calculations is described. The electrostatic field distribution outside the electrodes is derived. As well as giving electron spectra ({beta} disintegration and conversion electrons) the apparatus make s it possible to study e-{gamma}, e-{beta}, e-e-{gamma} and e-e-{beta} coincidences. In the last part are given experimental characteristics and the results of the first measurements made on conversion electron spectra ({sup 161}Tb, {sup 151}Pm, {sup 155}Eu) and on coincidences ({sup 170}Tm) using this spectrometer. (author) [French] Apres une etude bibliographique montrant l'interet que presente un spectrometre electrostatique a electrodes spheriques pour l'etude des schemas de desintegration, l'auteur etablit les caracteristiques theoriques d'un tel appareil (determination de l'equation des trajectoires calcul de la transmission et du pouvoir de resolution cas d'une source ponctuelle et d'une source etendue). On decrit l'appareil realise d'apres ces calculs. On etablit la repartition du champ electrostatique a l'exterieur des electrodes. Outre le trace des spectres d'electrons (desintegration {beta} et electrons de conversion), l'appareil permet l'etude de coincidences e-{gamma}, e-{beta}, e-e-{gamma} and e-e-{beta}. Dans la derniere partie, sont donnees les caracteristiques experimentales et les premieres etudes de spectres d'electrons de conversion ({sup 161}Tb, {sup 151}Pm, {sup 155}Eu) et de coincidences ({sup 170}Tm) faites a l'aide de ce spectrometre. (auteur)

  5. Study of the properties of an electron linac beam by means of the electromagnetic fields associated with the beam; Etude des proprietes du faisceau d'electrons d'un accelerateur lineaire au moyen des champs electromagnetiques associes a ce faisceau

    Energy Technology Data Exchange (ETDEWEB)

    Bergere, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-07-01

    For measuring the diverse characteristic parameters of a Linac electron beam, the one method causing the least perturbation to the electron beam itself, consists in the detection of signals induced in certain types of detectors by the electromagnets fields associated with the beam. Some particular detectors are then described, for measuring the following characteristic parameters of a Linac electron beam; a) electron beam peak current, a) longitudinal dimension and density of an elementary electron bunch, c) phase position of the electrons on the travelling sine wave of the accelerating field, d) transverse position of the beam. These particular electrodes are then used to provide experimental data In order to check the theoretical computations giving the longitudinal and transversal motions Of the electrons during their acceleration. (author) [French] Parmi les methodes de mesure des diverses caracteristiques du faisceau d'electrons d'un accelerateur lineaire, celles qui perturbent le moins le faisceau sont les methodes dans lesquelles l'energie du signal de mesure provient de la perturbation par l'electrode de mesure des champs electromagnetiques associes au faisceau. On decrit les electrodes de ce type qui ont ete mises au point pour mesurer les caracteristiques suivantes du faisceau d'electrons: a) courant crete, b) extension en phase d'un paquet elementaire d'electrons, c) phase d'accrochage des electrons, d) position transversale moyenne des electrons. On decrit ensuite comment les signaux provenant de ces diverses electrodes peuvent etre utilises pour verifier experimentalement les previsions theoriques des mouvements longitudinaux et transversaux des electrons en cours d'acceleration. (auteur)

  6. Study of the properties of an electron linac beam by means of the electromagnetic fields associated with the beam; Etude des proprietes du faisceau d'electrons d'un accelerateur lineaire au moyen des champs electromagnetiques associes a ce faisceau

    Energy Technology Data Exchange (ETDEWEB)

    Bergere, R. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-07-01

    For measuring the diverse characteristic parameters of a Linac electron beam, the one method causing the least perturbation to the electron beam itself, consists in the detection of signals induced in certain types of detectors by the electromagnets fields associated with the beam. Some particular detectors are then described, for measuring the following characteristic parameters of a Linac electron beam; a) electron beam peak current, a) longitudinal dimension and density of an elementary electron bunch, c) phase position of the electrons on the travelling sine wave of the accelerating field, d) transverse position of the beam. These particular electrodes are then used to provide experimental data In order to check the theoretical computations giving the longitudinal and transversal motions Of the electrons during their acceleration. (author) [French] Parmi les methodes de mesure des diverses caracteristiques du faisceau d'electrons d'un accelerateur lineaire, celles qui perturbent le moins le faisceau sont les methodes dans lesquelles l'energie du signal de mesure provient de la perturbation par l'electrode de mesure des champs electromagnetiques associes au faisceau. On decrit les electrodes de ce type qui ont ete mises au point pour mesurer les caracteristiques suivantes du faisceau d'electrons: a) courant crete, b) extension en phase d'un paquet elementaire d'electrons, c) phase d'accrochage des electrons, d) position transversale moyenne des electrons. On decrit ensuite comment les signaux provenant de ces diverses electrodes peuvent etre utilises pour verifier experimentalement les previsions theoriques des mouvements longitudinaux et transversaux des electrons en cours d'acceleration. (auteur)

  7. On homogenization of stokes flow in slowly varying media with applications to fluid–structure interaction

    KAUST Repository

    Brown, Donald L.

    2011-09-11

    In this paper we establish corrector estimates for Stokes flow in slowly varying perforated media via two scale asymptotic analysis. Current methods and techniques are often not able to deal with changing geometries prevalent in applied problems. For example, in a deformable porous medium environment, the geometry does not remain periodic under mechanical deformation and if slow variation in the geometry occurs. For such problems, one cannot use classical homogenization results directly and new homogenization results and estimates are needed. Our work uses asymptotic techniques of Marusic-Paloka and Mikelic (Bollettino U. M. I 7:661-671, 1996) where the authors constructed a downscaled velocity which converges to the fine-scale velocity at a rate of ε1/6 where ε is the characteristic length scale. We assume a slowly varying porous medium and study homogenization and corrector estimates for the Stokes equations. Slowly varying media arise, e. g., in fluid-structure interaction (FSI) problems (Popov et al. in Iterative upscaling of flows in deformable porous media, 2008), carbonation of porous concrete (Peter in C. R. Mecanique 335:357-362, 2007a; C. R. Mecanique 335:679-684, 2007b), and various other multiphysics processes. To homogenize Stokes flows in such media we restate the cell problems of Marusic-Paloka and Mikelic (Bollettino U. M. I 7:661-671, 1996) in a moving RVE framework. Further, to recover the same convergence properties it is necessary to solve an additional cell problem and add one more corrector term to the downscaled velocity. We further extend the framework of Marusic-Paloka and Mikelic (Bollettino U. M. I 7:661-671, 1996) to three spatial dimensions in both periodic and variable pore-space cases. Next, we also propose an efficient algorithm for computing the correctors by solving a limited number of cell problems at selected spatial locations. We present two computational examples: one for a constructed medium of elliptical perforations, and

  8. Application of a powder sintering-extrusion process to the fabrication of U-Al and UO{sub 2}-stainless steel dispersed fuel elements; Application de frittage-filage de poudres a la fabrication d'elements combustibles disperses U-Al et UO{sub 2} inox

    Energy Technology Data Exchange (ETDEWEB)

    Meny, L.; Buffet, J.; Sauve, Ch.

    1962-07-01

    Within the scope of an investigation of dispersion-type fuel elements, the fabrication by extrusion and sintering of cladded bars and tubes with core of either uranium-aluminum or uranium oxide-stainless steel fuel was investigated. The powder mixtures are first pre-densified in a 'pot', whereupon the sheathed compact is degassed and sealed in a vacuum by electron-beam welding. The subsequent co-extrusion is performed at low temperature and with slow pressure application in the case of U-Al dispersions; and at high temperature with rapid pressure application, using the Ugine-Sejournet process, in the case of UO{sub 2}-stainless steel dispersions. The procedure permits the production of practically fully dense bars and tubes more than 1 m. in length and 10-30 mm in diameter, the wall thickness of the tubes ranging from 2-5 mm. The physical and mechanical characteristics of the dispersion, as well as the mechanical characteristics of the cladded elements, were investigated as a function of the uranium content and the temperature. (authors) [French] Dans le cadre de l'etude des elements combustibles disperses, nous avons etudie la fabrication par frittage-filage de barreaux et de tubes gaines renfermant un noyau combustible soit en uranium-aluminium, soit en UO{sub 2}-inox. Les melanges de poudres sont comprimes dans un 'pot'. La billette composite ainsi obtenue est degazee, fermee et soudee sous vide par bombardement electronique. Le cofilage est ensuite effectue, a basse temperature et sur presse lente pour les disperses U-Al, a haute temperature et sur presse rapide par le procede Ugine-Sejournet pour les disperses UO{sub 2}-inox. Nous avons ainsi obtenu des barres et des tubes de porosite pratiquement nulle de plus de 1 metre de longueur et de 10 a 30 mm de diametre; les epaisseurs des tubes sont comprises entre 2 et 5 mm. Les proprietes physiques et mecaniques des disperses ainsi que les proprietes mecaniques des ensembles gaines, ont ete etudiees en fonction de

  9. Irradiation of UO{sub 2} sheathed in thick tubes effect of initial gap; Irradiation d'oxyde d'uranium en gaine resistante effet du jeu diametral initial sur le comportement global (programme CC-7: 1. et 2. tranches)

    Energy Technology Data Exchange (ETDEWEB)

    Janvier, J C; De Bernardy de Sigoyer, B.; Delmas, R [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1967-07-01

    Sixteen fuel elements made of thick zircaloy tubes containing sintered UO{sub 2}, were irradiated to burn-ups of 3000 resp. 6000 MWd/t. The specific power was continuously measured for each element. The initial diametral clearance was either 0.31 mm (free thermal expansion) or 0.12 mm (thermal expansion stress). The examinations of irradiated fuel elements suggest that : - when the initial gap is high, the fuel expands until it comes in close contact to the sheath; the thermal resistance between fuel and sheath is higher than in the case the fuel is stressed. - a central hole and lenticular voids in movement toward the center by evaporation - condensation can be seen only in specimens having the highest initial gap. - some fission products are concentrated at a certain distance from the center, corresponding to bright rings {beta} autoradiography pictures; that event occurs only in large gap specimens. - fission gas release does not seem to be influenced by mechanical stresses applied to the fuel; the fraction released is coherent, in every, case, with the probable temperature distribution. (authors) [French] Seize cartouches d'oxyde d'uranium fritte a gaines tres epaisses de zircaloy ont ete irradiees dans des conditions de puissance calorifique mesurees continument. Pour huit de ces cartouches le jeu diametral initial entre UO{sub 2} et gaine etait de 0,31 mm et le combustible etait libre de se dilater; pour les huit autres 3 soumises aux memes conditions d'irradiation, le jeu initial etait de 0,12 mm, de sorte que le combustible se trouvait comprime par dilatation differentielle. Les taux de combustion etaient soit de 3000, soit de 6000 MWj/t. Les examens post-irradiatoires suggerent que; - lorsque la jeu initial est eleve, l'UO{sub 2} se dilate jusqu'a venir pratiquement en contact avec la gaine; la resistance thermique a l'interface est alors nettement plus grande que lorsqu'il y a compression mecanique. - la presence d'une cheminee centrale et l'existence de

  10. The Grand Quevilly thermal test station - the SMW sodium circuit with a generator of superheated steam at 545 deg; Station d'essais thermiques de grand quevilly - circuit de sodium de 5 MW avec generateur de vapeur surchauffee a 545 deg

    Energy Technology Data Exchange (ETDEWEB)

    Robin, M G [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    A 5 MW installation is described which is a reduced model of the heat exchange system of a sodium-cooled reactor. This plant, which is situated at Grand Quevilly (near Rouen), consists of: 1 - A primary sodium loop made up of a sodium re-heater running on heavy diesel oil, a mechanical pump and an intermediate exchanger made up of clusters of tubes fitted with baffles. 2 - A NaK(56 per cent of K) secondary loop consisting mainly of a mechanical pump and a double-wall steam generator with forced circulation and complete vaporization. 3 - A tertiary water loop consisting of the inside of the steam generator pipes, a pressure-reducing valve which cools down the super-heated fluid and acts as a turbine, a condenser, a charge-pump and a supply pump for the boiler. The heat is given finally to a water-source flowing into the Seine. Two important points of the installation are: - The water treatment unit - The control and regulation system Apart from the general satisfactory operation of the installation which it is hoped to obtain, a careful study will be made of the heat transmission coefficients of the important equipment such as the intermediate exchanger and the steam generator. The construction was finished on April 28, 1964. (author) [French] On decrit une installation de 5 MW figurant a echelle reduite un systeme de transfert de chaleur d'un reacteur refroidi au sodium. Cette installation, situee a Grand Quevilly (pres de Rouen) comprend: 1 - Une boucle de sodium primaire comportant un rechauffeur de sodium alimente en fuel lourd, une pompe mecanique et un echangeur intermediaire a faisceau tubulaire muni de chicanes, 2 - Une boucle de NaK (56% de K) secondaire dont les appareils principaux sont une pompe mecanique et un generateur de vapeur a double paroi, circulation forcee et vaporisation totale. 3 - une boucle tertiaire a eau comprenant l'interieur des tubes du generateur de vapeur, un detendeur-desurchauffeur simulant une turbine, un condenseur, une pompe de

  11. Tensile deformations in mono- and polycrystalline uranium between 20 deg. C and -196 deg. C; Deformation par traction de l'uranium mono- et polycristallin entre 20 deg. C et -196 deg. C

    Energy Technology Data Exchange (ETDEWEB)

    Lemogne, A [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-06-01

    Tensile stress tests been carried out at low temperatures (between 20 C and -196 C) on monocrystalline and polycrystalline uranium of various purities. The mechanical properties of the monocrystals have been related, at all temperatures, to plastic flow mechanisms. Below -100 C brittle fracture occurs on the planes making up the twins. A detailed study of the plastic behaviour at -196 C has made it possible to show that all the twin planes except the [176] plane were liable to become privileged planes for brittle fracture. The mechanical properties of the polycrystals, the breaking stress and the elongation at breaking point, decrease as the temperature decreases from 20 to -196 C; they undergo a transition however - not to be confused with the ductile-brittle transition - whose position and strength depend on the grain size and on the purity. It has been verified also that Petch's law is approximately applicable to the plastic flow and rupture stresses; a study has also been made of the influence of temperature and purity on the constants occurring in this equation. Finally, experiments at -196 C on the deformation up to breaking point of polycrystalline samples cold-worked at 20 C have shown the importance of the role played by intergranular cracks in the plastic behaviour of uranium. (author) [French] Des essais de traction ont ete realises a basse temperature (entre 20 C et -196 C, sur des monocristaux et des polycristaux d'uranium de differentes puretes. Les proprietes mecaniques des monocristaux ont ete reliees, a toutes temperatures, aux mecanismes d'ecoulement plastique. Une rupture fragile intervient a partir de -100 C sur les plans de composition de macle. L'etude detaillee du comportement plastique a -196 C a permis de preciser que tous les plans de macle, sauf [176], etaient susceptibles de devenir des plans de rupture fragile privilegies. Les proprietes mecaniques des polycristaux, contrainte de rupture et allongement a la rupture, decroissent quand on

  12. Study of super-conductors in the aluminium-magnesium system; Etude des supraconducteurs du systeme aluminium-magnesium

    Energy Technology Data Exchange (ETDEWEB)

    Bonnin, B [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1965-05-01

    The author has designed and built an apparatus for the measurement of the magnetization of superconducting alloys by the classical method of extraction. Its originality is due to the employment of a cryostat having two helium baths. The lowest temperature reached by pumping on the innermost helium bath using a primary pump combined with a BOOSTER pump is 0.75 deg. K. Temperatures are determined with a aid of Hartshorn bridge. With this apparatus, it has been possible to study the influence of extended defects on the irreversible behaviour of the magnetization of aluminium-magnesium alloys. It has been shown that the effect of these defects is important chiefly in the superconductors alloys of the second kind. The introduction of the extended defects was controlled by electron microscopy and by the measure of the residual resistivities. Finally, the author has measured for these alloys the critical fields Hc, Hc1, Hc2, the transition temperatures Tc and the coefficients of electronic specific heat {gamma}. (author) [French] L'auteur a realise un appareillage lui permettant de mesurer l'aimantation d'alliages supraconducteurs par la methode classique d'extraction. L'originalite du montage reside en la construction d'un cryostat a double bain d'helium. La temperature la plus basse atteinte en pompant sur le bain d'helium interieur a l'aide d'une pompe BOOSTER est de 0.75 deg. K. Les temperatures sont determinees a l'aide d'un pont de Hartshorn. C'est avec cet appareillage que l'auteur a pu etudier l'influence des defauts etendus sur le comportement irreversible de l'aimantation d'alliages d'aluminium-magnesium. Il a montre que l'influence de ces defauts est essentiellement sensible dans les alliages supraconducteurs de la deuxieme espece. L'introduction des defauts etendus a ete controlee par microscopie electronique et par mesure de resistivite residuelle. Enfin, pour tous ces alliages ont ete mesures: les champs critiques Hc, Hc1, Hc2, les temperatures critiques Tc

  13. Feasibility study for the construction of a methane production plant on the basis of 'green waste' collected in the canton of Ticino; Machbarkeitsstudie Biogasanlage im Tessin -- Studio di fattibilita di un impianto di biometanizzazione per i rifiuti verdi

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-07-01

    This report for the Swiss Federal Office of Energy presents a feasibility study for the construction of a methane production plant on the basis of 'green waste' collected in the canton of Ticino, in Southern Switzerland. The objective is power generation from compostable organic waste (about 10'000 t/year) and marketing of this electrical energy under a 'clean energy' label. The biogas process together with the technologies used are described. A review of the methane production plants available today on the European market is given, together with a presentation of some manufacturers. The local situation in Ticino, including available volume and composition of green waste as well as the possible usages for the residues from the methane production plants, is discussed. Potential sites for the future production plant are listed. Economic aspects are summarised in the form of diagrams. In annexes, more details on the plant operation cost are given and pictures of the different fermentation installation candidates are presented. [French] Ce rapport est le resultat de l'etude de la faisabilite de l'implantation d'une usine de methanisation des dechets verts pour le canton du Tessin en Suisse. L'objectif est de valoriser l'energie des dechets compostables (typiquement 10'000 t/an) et d'en produire de l'energie electrique qui sera vendue sous un label d'energie propre. Le processus de biomethanisation est presente, de meme que les techniques utilisees. Suit une presentation des diverses installations de methanisation actuellement disponibles sur le marche europeen et des entreprises qui les proposent. La situation propre au Tessin comme la quantite et la composition des dechets verts et les possibilites d'utilisation des masses residuelles est analysee. Le lieu d'implantation de l'usine est aussi discute. Finalement, un bilan economique est presente sous forme graphique. Le document est

  14. Spectroscopic study of near closed-shell nuclei Z = 50, by means of the ({sup 3}He,d) and (d, {sup 3}He) reactions on all even tin isotopes, and the ({sup 3}He, d) reaction on the A = 113 and A = 115 indium isotopes; Etude spectroscopique des noyaux au voisinage de la couche fermee Z = 50, au moyen des reactions ({sup 3}He, d) et (d, {sup 3}He) sur tous les isotopes pairs de l'etain, et de la reaction ({sup 3}He, d) sur les isotopes 113, 115 de l'indium

    Energy Technology Data Exchange (ETDEWEB)

    Harar, S. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-06-01

    A systematic study of ({sup 3}He, d) reactions at 18 MeV incident energy and (d, {sup 3}He) reactions at 22 MeV incident energy on {sup 112,114,116,118,120,122,124}Sn is presented. The distorted wave Born approximation (DWBA) is used to extract informations on (a) the transferred angular momentum l{sub p}, (b) the change of parity and (c) the spectroscopic factor. We have investigated the influence of the proton-neutron residual interaction on the spread of the pure proton configuration (particle or hole), and on the observed level sequence. Experimental results and predictions of the Kisslinger and Sorensen model are in reasonable agreement. A study of {sup 113,115}In ({sup 3}He, d) {sup 114,116}Sn reactions shows strong experimental evidence that the proton particle hole components are weak in the first excited states of tin nuclei. Furthermore, highly excited states ({approx} 4 to 6 MeV) having a simple structure with one predominant particle-hole configuration have been located. (authors) [French] Nous presentons une etude systematique des reactions ({sup 3}He, d) a 18 MeV et (d, {sup 3}He) a 22 MeV sur {sup 112,114,116,118,120,122,124}Sn. L'approximation des ondes deformees (DWBA) est utilisee pour obtenir des informations sur le moment angulaire transfere l{sub p}, sur le changement de parite et le facteur spectroscopique. Nous avons etudie l'influence de l'interaction residuelle proton-neutron sur la repartition de l'intensite a une seule particule ou trou de proton, et sur les sequences des niveaux observes. Les resultats experimentaux et les previsions theoriques du modele de Kisslinger et Sorensen sont en assez bon accord. L'etude des reactions {sup 113,115}In ({sup 3}He, d) {sup 114,116}Sn apporte la preuve experimentale que les composantes particule - trou de protons des premiers etats excites des noyaux residuels sont faibles. Elle permet aussi de localiser des niveaux a une energie d'excitation elevee ({approx} 4 a 6 Me

  15. Spectroscopic study of near closed-shell nuclei Z = 50, by means of the ({sup 3}He,d) and (d, {sup 3}He) reactions on all even tin isotopes, and the ({sup 3}He, d) reaction on the A = 113 and A = 115 indium isotopes; Etude spectroscopique des noyaux au voisinage de la couche fermee Z = 50, au moyen des reactions ({sup 3}He, d) et (d, {sup 3}He) sur tous les isotopes pairs de l'etain, et de la reaction ({sup 3}He, d) sur les isotopes 113, 115 de l'indium

    Energy Technology Data Exchange (ETDEWEB)

    Harar, S [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-06-01

    A systematic study of ({sup 3}He, d) reactions at 18 MeV incident energy and (d, {sup 3}He) reactions at 22 MeV incident energy on {sup 112,114,116,118,120,122,124}Sn is presented. The distorted wave Born approximation (DWBA) is used to extract informations on (a) the transferred angular momentum l{sub p}, (b) the change of parity and (c) the spectroscopic factor. We have investigated the influence of the proton-neutron residual interaction on the spread of the pure proton configuration (particle or hole), and on the observed level sequence. Experimental results and predictions of the Kisslinger and Sorensen model are in reasonable agreement. A study of {sup 113,115}In ({sup 3}He, d) {sup 114,116}Sn reactions shows strong experimental evidence that the proton particle hole components are weak in the first excited states of tin nuclei. Furthermore, highly excited states ({approx} 4 to 6 MeV) having a simple structure with one predominant particle-hole configuration have been located. (authors) [French] Nous presentons une etude systematique des reactions ({sup 3}He, d) a 18 MeV et (d, {sup 3}He) a 22 MeV sur {sup 112,114,116,118,120,122,124}Sn. L'approximation des ondes deformees (DWBA) est utilisee pour obtenir des informations sur le moment angulaire transfere l{sub p}, sur le changement de parite et le facteur spectroscopique. Nous avons etudie l'influence de l'interaction residuelle proton-neutron sur la repartition de l'intensite a une seule particule ou trou de proton, et sur les sequences des niveaux observes. Les resultats experimentaux et les previsions theoriques du modele de Kisslinger et Sorensen sont en assez bon accord. L'etude des reactions {sup 113,115}In ({sup 3}He, d) {sup 114,116}Sn apporte la preuve experimentale que les composantes particule - trou de protons des premiers etats excites des noyaux residuels sont faibles. Elle permet aussi de localiser des niveaux a une energie d'excitation elevee ({approx} 4 a 6 MeV), ayant une structure simple a

  16. Study of once and twice forbidden {beta} transitions; Contribution a l'etude de transitions {beta} une fois et deux fois interdites

    Energy Technology Data Exchange (ETDEWEB)

    Hocquenghem, J C [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1967-09-01

    The realisation of an experimental set up for directional angular correlation measurements allowed us to determine {beta} - {gamma} angular correlations. These measurements together with the determination of the {beta} shape-factor have been made for the following transitions: the first forbidden {beta}{sup -} transitions of 386 keV in the {sup 177}Lu disintegration and of 352 keV in the {sup 175}Yb disintegration. The experimental results have been compared with theoretical predictions of the Nilsson's model; the twice forbidden {beta}{sup -} transition of 473 keV in the {sup 94}Nb disintegration. The {beta} transition nuclear matrix elements have been extracted from the experimental results. Comparison have been made with the theoretical values calculated by taking for nuclear wavefunctions those obtained by diagonalization of the residual interaction and assuming that protons and neutrons outside the {sup 90}Zr core are respectively on the 1 g 9/2 and 2 d 5/2 orbits. (author) [French] La realisation d'un ensemble de mesures de correlations angulaires directionnelles nous a permis la mesure de correlations {beta} - {gamma} en fonction de l'energie. En completant celles-ci par la mesure du facteur de forme du spectre {beta}, nous avons pu etudier ainsi: d'une part, les transitions {beta}{sup -} une fois interdites de 386 keV de la desintegration de {sup 177}Lu et de 352 keV de la desintegration de {sup 175}Yb, Les resultats experimentaux ont ete compares aux valeurs calculees dans le modele de Nilsson; d'autre part, la transition {beta}- deux fois interdite de 473 keV de la desintegration de {sup 94}Nb. Les elements de matrice nucleaire de la transition {beta}, extraits des resultats experimentaux, ont ete compares aux valeurs theoriques calculees. Les fonctions d'ondes nucleaires utilisees ont ete obtenues par diagonalisation de l'interaction residuelle en supposant que les protons et les neutrons, en dehors du coeur forme par le {sup 90}Zr, sont respectivement

  17. Use of a thin-film evaporator for bitumen coating of radioactive concentrates; Utilisation d'un evaporateur a couche mince pour l'enrobage par le bitume de concentrats radioactifs

    Energy Technology Data Exchange (ETDEWEB)

    Lefillatre, G; Rodier, J; Hullo, R; Cudel, Y; Rodi, L [Commissariat a l' Energie Atomique, Chusclan (France). Centre de Production de Plutonium de Marcoule

    1969-07-01

    pour cent de bitume (Mexphalte 40/50), la teneur en eau residuelle de l'enrobe restant inferieure a 0.5 pour cent. Une deuxieme serie d'essais sera prochainement realisee sur cette installation pilote avec notamment des emulsions bitumineuses a base de Mexphalte 40/50 et 80/100. (auteurs)

  18. Applications of electrical resistivity measurements to research into the purification of uranium using floating molten zone by electronic bombardment; Applications des mesures de resistivite electrique a l'etude de la purification de l'uranium par fusion de zone flottante par bombardement electronique

    Energy Technology Data Exchange (ETDEWEB)

    Pascal, J L [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-02-01

    un examen micrographique, des mesures de microdurete et des essais de recristallisation secondaire, a permis d'apprecier le nouveau degre de purete de l'uranium obtenu. L'examen de ce degre de purete a ete poursuivi par des mesures de resistivite electrique a 20 deg. K. Mais on a du tenir compte dans l'interpretation de ces mesures, de l'anisotropie de resistivite de l'uranium {alpha} a 20 deg. C et de l'influence de l'etat structural sur la resistivite residuelle. Ces mesures ont conduit, en determinant les resistivires de monocristaux d'uranium {alpha}, a distinguer les resistivites principales suivant les axes [100] et [010]. (auteur)

  19. Effect of temperature on the valency bands of HDO in water in the liquid and solid states. Effects on the analysis of heavy water using infra-red absorption; Effet de temperature sur les bandes de valence de HDO dans l'eau a l'etat liquide et a l'etat solide - consequences pour l'analyse de l'eau lourde par absorption infra-rouge

    Energy Technology Data Exchange (ETDEWEB)

    Ceccaldi, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    After, a description of the technique used, a qualitative examination is made of the influence of the temperature on the {nu}{sub OH}(3,400 cm{sup -1}) and {nu}{sub OD} (2,500 cm{sup -1}) valence bands of HDO in the liquid state and then during the passage to the solid state. Quantitative examination with two cells of different thickness makes it possible to define the influence of temperature on the residual absorption of the pure liquid (D{sub 2}O or H{sub 2}O and on the valency bands ({nu}{sub OH} and {nu}{sub OD} respectively). It is found that a similar change occurs in the two bands but that the changes in the background are very different. During the passage from the liquid to the solid state the shape of the bands varies considerably but little change occurs in the total intensity. It has been possible to express these results in a simple form which is directly applicable to analytical problems. (authors) [French] Apres un rappel de la technique utilisee, on examine qualitativement l'influence de la temperature sur les bandes de valence {nu}{sub OH} (3400 cm{sup -1}) et {nu}{sub OD} (2500 cm{sup -1}) de HDO a l'etat liquide puis le passage a l'etat solide. L'examen quantitatif, avec deux cuves d'epaisseurs differentes, permet de preciser l'influence de la temperature sur l'absorption residuelle du liquide pur (D{sub 2}O ou H{sub 2}O) et sur les bandes de valence ( {nu}{sub OH} et {nu}{sub OD} respectivement). On constate une evolution parallele de ces bandes mais un comportement tres different du fond continu. Lors du passage de l'etat liquide a l'etat solide, la forme des bandes varie considerablement mais non l'intensite totale. On a pu formuler ces resultats sous une forme simple applicable directement aux problemes analytiques. (auteurs)

  20. The accelerator tube of ions of the generator Van de Graaff of the CEA. Survey of development. First results; Le tube accelerateur d'ions du generateur van de graapp du commissariat. Etude de developpement. Premiers resultats

    Energy Technology Data Exchange (ETDEWEB)

    Bruck, H.; Prevot, F. [Commissariat a l' Energie Atomique, Saclay(France). Centre d' Etudes Nucleaires

    1953-07-01

    Rare are the Van de Graaff supplies whose tube doesn't collapse electrically to tensions and currents very lower to those that the generator can provide. We chose the general measurements: length and diameter, and put the accent on the survey of the individual element, so much to the mechanical viewpoint (installation, solidity, tightness and degassing), that to the electric viewpoint (to increase the electric rigidity of it). After modification the breakdown voltage as well as the performances of the tube have been improved greatly. (M.B.) [French] Rares sont les machines de Van de Graaff dont le tube ne s'effondre pas electriquement a des tensions et des courants bien inferieurs a ceux que le generateur peut fournir. Nous avons choisi les dimensions generales: longueur et diametre, et mis l'accent sur l'etude de l'element individuel, tant au point de vue mecanique (montage, solidite, etancheite et degazage), qu'au point de vue electrique (pour en augmenter la rigidite electrique). Apres modification la tension de claquage ainsi que les performances du tube ont ete grandement ameliorees. (M.B.)

  1. The compatibility of various austenitic steels with molten sodium (1963); Compatibilite de divers aciers austenitiques avec le sodium fondu (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Champeix, L; Sannier, J; Darras, R; Graff, W; Juste, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1963-07-01

    Various techniques for studying corrosion by molten sodium have been developed and applied to the case of 18/10 austenitic steels. The results obtained are discussed as a function of various parameters: type of steel, temperature, oxygen content of the sodium, surface treatment, welds, mechanical strain. In general, these steels have an excellent resistance to sodium when the oxygen content is limited by a simple purification system of the 'cold trap' type, and when an attempt is made to avoid cavitation phenomena which are particularly dangerous, as is shown by the example given. (authors) [French] Des techniques d'etude de la corrosion par le sodium fondu en circulation ont ete mises au point et appliquees au cas des aciers austenitiques 18/10. Les resultats obtenus sont discutes en fonction de differents parametres: nuance de l'acier, temperature, teneur en oxygene du sodium, traitement de surface, soudure, contrainte mecanique. D'une maniere generale, ces aciers ont une excellente tenue dans le sodium lorsque, sa teneur en oxygene est limitee par un systeme simple de purification du type ''piege froid'' et lorsque l'on fait en sorte d'eviter les phenomenes de cavitation particulierement dangereux, comme il ressort d'un exemple cite. (auteurs)

  2. Investigation of the kinetics of the reactions of oxidation, nitration, and hydrogenation of uranium; Etude cinetique de l'oxydation, de la nitruration et de l'hydruration de l'uranium

    Energy Technology Data Exchange (ETDEWEB)

    Adda, Y [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1955-06-15

    Various physico-chemical methods have been used to investigate the kinetics of the oxidation hydridation and nitridation of uranium. The experimental results show that the kinetics of these reactions are influenced by many factors also the Pilling and Bedworth rule is valid only under very limited conditions. The disagreement between this rule and the experimental results could be explained by the existence of numerous mechanical faults in the compounds obtained by the dry corrosion of the metal. (author) [French] Les cinetiques d'oxydation, d'hydruration et de nitruration de l'uranium ont ete etudiees au moyen de differentes methodes physico-chimiques. Les resultats experimentaux obtenus indiquent qu'un grand nombre de facteurs influencent les cinetiques d'attaque et que la regle de Pilling et Bedworth n'est verifiee que dans des cas tres limites. Les desaccords entre cette regle et les resultats experimentaux s'expliqueraient par l'existence de nombreux defauts mecaniques dans les composes obtenus par corrosion seche du metal. (auteur)

  3. Oxidation films morphology; Sur la morphologie des pellicules d'oxydation

    Energy Technology Data Exchange (ETDEWEB)

    Paidassi, J. [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    After studying the oxidation of several pure polyvalent metals (Fe, Cu, Mn, Ni, U) and of their oxides at high temperature and atmospheric pressure, the author suggests how to modify the usual representation of the oxide film (a piling of different oxide layers, homogeneous on a micrographic scale with a equi-axial crystallisation, free of mechanical tensions, with flat boundary surfaces) to have it nearer to reality. In this first part, the author exposes the study of the real micrographic structure of the oxidation film and gives examples of precipitation in the oxides during the cooling of the oxidised sample. (author) [French] En se basant sur les etudes qu'il a faites sur l'oxydation aux temperatures elevees et a la pression atmospherique de quelques metaux purs a valences multiples (Fe, Cu, Mn, Ni, U), et de leurs oxydes, l'auteur suggere comment le schema qui representerait la pellicule comme etant une superposition de diverses couches d'oxydes, homogenes micrographiquement, a cristallisations equiaxes, depourvues de tensions mecaniques et separees par des interfaces plans, doit etre modifie pour s'ajuster a la realite. Dans cette premiere partie, l'auteur etudie la structure micrographique reelle des pellicules d'oxydation et donne des exemples de precipitation dans les oxydes au cours du refroidissement des echantillons oxydes. (auteur)

  4. Modelling the fatigue behaviour of a stratified glass-epoxy composite: theoretical and experimental aspects; Modelisation du comportement en fatigue d`un composite stratifie verre-epoxyde: aspects theoriques et experimentaux

    Energy Technology Data Exchange (ETDEWEB)

    Verdiere, N.; Suri, C. [Laboratoire de mecanique appliquee, 25 - Besancon (France)

    1996-01-01

    Composite materials are used in the manufacture of water transport pipework for use in PWR`s. Estimation of their life expectancy relies on long and costly tests (ASTM D2992B standard). It would be extremely advantageous to have another method relying only on short laboratory tests which could be based on a mechanical behaviour and damage model. For several years, the Laboratoire de Mecanique Appliquee de Besancon has been developing a mechanical behaviour model for composite material tubes for different types of multiaxial stresses. However, this model does not take into account the fatigue behaviour. We therefore needed to find out how this type of stress could be incorporated into the model. To this end, research was undertaken in the form of a thesis (by E. Joseph) both to perfect the multiaxial fatigue stress testing machines and to take into account this type of behaviour in the mechanical model. This study covered glass fibre/epoxy resin composite material tubes and allowed their behaviour to be modelled. An important part of the work concerned the instrumentation and adaptation of test machines which hitherto did not exist so that the research could be carried out. For each of the stress axes (traction, internal pressure without vacuum effect ({Sigma}{sup zz}=0) and internal pressure with vacuum effect ({Sigma}{sup zz}=1/2{Sigma}{sup {theta}{theta}})), instantaneous behaviour was studied. Three stress levels and frequency values were used to define the fatigue behaviour. (authors). 23 refs., 41 figs., 5 tabs.

  5. Study of the hydro-mechanical behaviour of expanded graphite gaskets; Etude du comportement et de l`etancheite de joints en graphite expnase

    Energy Technology Data Exchange (ETDEWEB)

    Patron, E. [Electricite de France (EDF), Direction des Etudes et Recherches, 92 - Clamart (France)

    1997-12-31

    The poro-mechanical behaviour models developed by O. Coussy permit to consider various phenomena observed experimentally: thermo-hydro-mechanical couplings, plasticity, etc. The aim of this study is to implement the simplest poro-mechanical model (i.e. the isotropic linear poro-elastic model) to model the gasket hydro-mechanical behaviour. First, isotropic poro-elastic characteristics of expanded graphite have been estimated from these tests conducted at Departement Mecanique et Technologie des Composants (MTC) and data from literature. Then, analytical solutions of the tightness tests developed at the MTC Department have been carried out. These calculations provide a first estimation of porosity variations during a tightness tests with metal/metal contact or in elastic recovery, and during a `hot thermal transient`. Thickness controlled numerical calculations have proved the analytical calculations relevance. With regard to simulation of tests with metal/metal contact or `hot thermal transient`, stress controlled numerical calculations have pointed out: - a greater vertical displacement on the inner side of the graphite ring and - a z dependence of the radial displacement and thus a porous differential variation between the upper and lower faces of the ring. (author). 21 refs.

  6. The accelerator tube of ions of the generator Van de Graaff of the CEA. Survey of development. First results; Le tube accelerateur d'ions du generateur van de graapp du commissariat. Etude de developpement. Premiers resultats

    Energy Technology Data Exchange (ETDEWEB)

    Bruck, H; Prevot, F [Commissariat a l' Energie Atomique, Saclay(France). Centre d' Etudes Nucleaires

    1953-07-01

    Rare are the Van de Graaff supplies whose tube doesn't collapse electrically to tensions and currents very lower to those that the generator can provide. We chose the general measurements: length and diameter, and put the accent on the survey of the individual element, so much to the mechanical viewpoint (installation, solidity, tightness and degassing), that to the electric viewpoint (to increase the electric rigidity of it). After modification the breakdown voltage as well as the performances of the tube have been improved greatly. (M.B.) [French] Rares sont les machines de Van de Graaff dont le tube ne s'effondre pas electriquement a des tensions et des courants bien inferieurs a ceux que le generateur peut fournir. Nous avons choisi les dimensions generales: longueur et diametre, et mis l'accent sur l'etude de l'element individuel, tant au point de vue mecanique (montage, solidite, etancheite et degazage), qu'au point de vue electrique (pour en augmenter la rigidite electrique). Apres modification la tension de claquage ainsi que les performances du tube ont ete grandement ameliorees. (M.B.)

  7. Sinter aluminium as cladding material for fuel elements; Aluminium fritte comme materiau de gainage pour les elements combustibles

    Energy Technology Data Exchange (ETDEWEB)

    Mann, K E; Boudouresques, M B [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Otto Fuchs, Meinerzhagen, Westfalen (Germany)

    1961-07-01

    1. Survey of the production process of sinter aluminium. 2. Description of the forming processes (extrusion, forging and rolling), whereby the production of tubing for atom piles will be explained in detail. 3. Production of ribbed tubes and tubes with close tolerances of sizes. 4. The different SAP-qualities and their properties under special consideration of the properties at elevated temperatures and the creep properties. 5. Diffusion behaviour of SAP with Be, Mg, Al, U and UO{sub 2}. 6. Corrosion behaviour in CO{sub 2} atmosphere at high temperature and in water. 7. Weldability. 8. Effect of irradiation on the mechanical properties. 9. Superiority of SAP compared with normal wrought alloys of the same composition. (author) [French] 1. Apercu des processus de production de l'aluminium fritte. 2. Expose des operations de transformation (filageries, forgeage et laminage), avec explication detaillee de la fabrication de gaine pour reacteurs. 3. Fabrication de tubes canneles et de tubes avec de faibles tolerances. 4. Diverses proprietes de l'aluminium fritte SAP, notamment proprietes aux temperatures elevees et proprietes de fluage. 5. Diffusion de l'aluminium fritte SAP en presence de Be, Mg, Al, U et UO{sub 2}. 6. Resistance a la corrosion dans une atmosphere de CO{sub 2} a temperature elevee et dans l'eau. 7. Possibilites de soudage. 8. Effet de l'irradiation sur les proprietes mecaniques. 9. Superiorite de l'aluminium fritte SAP sur les alliages forges normaux de meme composition. (auteur)

  8. Oxidation films morphology; Sur la morphologie des pellicules d'oxydation

    Energy Technology Data Exchange (ETDEWEB)

    Paidassi, J [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    After studying the oxidation of several pure polyvalent metals (Fe, Cu, Mn, Ni, U) and of their oxides at high temperature and atmospheric pressure, the author suggests how to modify the usual representation of the oxide film (a piling of different oxide layers, homogeneous on a micrographic scale with a equi-axial crystallisation, free of mechanical tensions, with flat boundary surfaces) to have it nearer to reality. In this first part, the author exposes the study of the real micrographic structure of the oxidation film and gives examples of precipitation in the oxides during the cooling of the oxidised sample. (author) [French] En se basant sur les etudes qu'il a faites sur l'oxydation aux temperatures elevees et a la pression atmospherique de quelques metaux purs a valences multiples (Fe, Cu, Mn, Ni, U), et de leurs oxydes, l'auteur suggere comment le schema qui representerait la pellicule comme etant une superposition de diverses couches d'oxydes, homogenes micrographiquement, a cristallisations equiaxes, depourvues de tensions mecaniques et separees par des interfaces plans, doit etre modifie pour s'ajuster a la realite. Dans cette premiere partie, l'auteur etudie la structure micrographique reelle des pellicules d'oxydation et donne des exemples de precipitation dans les oxydes au cours du refroidissement des echantillons oxydes. (auteur)

  9. Identification of multiple modes of axisymmetric or circularly repetitive structures

    International Nuclear Information System (INIS)

    Kopff, P.

    1983-01-01

    The axisymmetric structures, or those composed with circularly repetitive elements, often display multiple modes, which are not easy to separate by modal identification of experimental responses. To be able to solve in situ some problems related to the vibrational behaviour of reactor vessels or other such huge structures, ELECTRICITY DE FRANCE developed a few years ago, experimental capabilities providing heavy harmonic driving forces, and elaborate data acquisition, signal processing and modal identification software, self-contained in an integrated mobile test facility. The modal analysis techniques we have developed with the LABORATOIRE DE MECANIQUE Appliquee of University of BESANCON (FRANCE) were especially suited for identification of multiple or separation of quasi-multiple modes, i.e. very close and strongly coupled resonances. Besides, the curve fitting methods involved, compute the same complex eigen-frequencies for all the vibration pick-ups, for better accuracy of the related eigen-vector components. Moreover, the latest extensions of these algorithms give us the means to deal with non-linear behaviour. The performances of these programs are drawn from some experimental results on axisymmetric or circularly repetitive structure, we tested in our laboratory to validate the computational hypothesis used in models for seismic responses of breeder reactor vessels. (orig.)

  10. Extraction apparatus used in the treatment of irradiated fuels; Les appareils d'extraction utilises dans le traitement des combustibles irradies

    Energy Technology Data Exchange (ETDEWEB)

    Faugeras, P; Talmont, X [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    The two qualities necessary in an extractor in the case of solvent extraction of radioactive materials are that they should occupy little space and require little maintenance. In this paper various types of apparatus designed to this effect are examined: firstly mixer-decanter types with mechanical shaking and with shaking and decantation ultrasonically accelerated; then pulsed columns; finally hydro-cyclones. The chemical engineering studies peculiar to the running, supply and control of each of these extractors are described in detail. In certain cases some results obtained on radioactive solutions on a pilot scale are given. (author) [French] Faible encombrement, peu d'entretien, telles sont les deux qualites qu'un extracteur doit posseder dans le cas d'extraction par solvant de matieres radioactives. Dans ce texte seront examines differents types d'appareils concus dans cet esprit: d'abord les appareils typez melangeurs-decanteurs a agitation mecanique, a agitation et decantation accelerees aux ultra-sons; puis les colonnes pulsees; enfin les hydrocyclones. Pour chacun de ces extracteurs seront detaillees les etudes de genie chimique propres a son fonctionnement, a son alimentation, a son controle. Pour certains seront notes quelques resultats obtenus sur des solutions radioactives a l'echelle pilote. (auteur)

  11. ASTRID: A 3D Eulerian software for subcooled boiling modelling - comparison with experimental results in tubes and annuli

    International Nuclear Information System (INIS)

    Briere, E.; Larrauri, D.; Olive, J.

    1995-01-01

    For about four years, Electricite de France has been developing a 3-D computer code for the Eulerian simulation of two-phase flows. This code, named ASTRID, is based on the six-equation two-fluid model. Boiling water flows, such as those encountered in nuclear reactors, are among the main applications of ASTRID. In order to provide ASTRID with closure laws and boundary conditions suitable for boiling flows, a boiling model has been developed by EDF and the Institut de Mecanique des Fluides de Toulouse. In the fluid, the heat and mass transfer between a bubble and the liquid is being modelled. At the heating wall, the incipient boiling point is determined according to Hsu's criterion and the boiling heat flux is split into three additive terms: a convective term, a quenching term and a vaporisation term. This model uses several correlations. EDF's program in boiling two-phase flows also includes experimental studies, some of which are performed in collaboration with other laboratories. Refrigerant subcooled boiling both in tubular (DEBORA experiment, CEN Grenoble) and in annular geometry (Arizona State University Experiment) have been computed with ASTRID. The simulations show the satisfactory results already obtained on void fraction and liquid temperature. Ways of improvement of the model are drawn especially on the dynamical part

  12. Physics of phenomena in the zone close to an underground nuclear explosion; Physique des phenomenes en zone proche des explosions nucleaires souterraines

    Energy Technology Data Exchange (ETDEWEB)

    Maury, J; Levret, C [Commissariat a l' Energie Atomique, Bruyeres-le-Chatel (France). Centre d' Etudes

    1969-07-01

    After a description of the phenomenology of underground explosions, the basic laws governing the propagation in the ground of the energy produced by the explosion are given. The reports considers hydrodynamics, the mechanics of solids, the equations of state for solids and gases in the case of very high and medium pressures, and the dynamical strength of solids. These various elements make it possible to draw up a system of equations which define completely the changes with time of the shock-wave produced in the ground by the explosion. (authors) [French] Apres une description de la phenomenologie des explosions souterraines, on expose les lois fondamentales regissant la propagation dans le sol de l'energie degagee par l'explosion. L'expose comprend des developpements sur l'hydrodynamique, la mecanique des solides, les equations d'etat des solides et des gaz, aux tres fortes et moyennes pressions, et sur la resistance dynamique des solides. Ces differents elements permettent d'ecrire un systeme d'equations qui definissent completement l'evolution dans le temps de l'onde de choc emise dans le sol par l'explosion. (auteurs)

  13. Contribution to the study of the microstructure of uranium dioxide (1962); Contribution a l'etude de la microstructure du dioxyde d'uranium (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Porneuf, A [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1960-05-15

    The microstructure of sintered uranium dioxide is studied in relation with several parameters, specially the sintering temperatures and atmospheres. The external surface and the internal microstructure of the sintered are examined, using fractography and ceramography. Various techniques for preparing surfaces (mechanical and electrolytic polishing) and for revealing the structure (chemical and anodic attack, ionic bombardment oxidation) have been experienced and compared. Patterns similar to those revealed in metals and probably related with interactions between dislocations and vacancies have been observed. (author) [French] La microstructure de frittes d'oxyde d'uranium est etudiee en fonction de divers parametres, en particulier de la temperature et de l'atmosphere de frittage, par examen de la surface externe des frittes, puis de leur microstructure interne (fractographie, ceramographie). Differentes techniques de preparation des surfaces (polissage mecanique ou electrolytique) et de revelation de la structure (attaque chimique ou anodique, bombardement ionique, oxydation preferentielle) ont ete experimentees et comparees. Des figures comparables a celles revelees dans les metaux et liees probablement a des interactions entre dislocations et lacunes ont ete observees. (auteur)

  14. X-ray study of the structure of polyethylene at the scale of 100-200 Angstrom; Etude par rayons X dela structure du polyethylene a l'echelle de 100-200 Angstrom

    Energy Technology Data Exchange (ETDEWEB)

    Belbeoch nee Goldsztein, B [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1958-06-15

    Information on the structure of polyethylene is deduced from a comparison of the results obtained by central diffusion and by other X-ray methods. The structure depends on the thermal and mechanical treatment to which the samples are subjected, as well as on the observation temperature. The central diffusion due to the heterogeneity of the material at the scale of 100-200 Angstrom is bound up with the presence of both the amorphous and crystalline phases. Stretched polythene shows a more or less regular succession of orderly and disorderly regions. When released it has a structure of recrystallisation preceded by 'amorphization'. (author) [French] Les informations sur la structure du polyethylene sont deduites de la confrontation des resultats obtenus par la diffusion centrale et par d'autres methodes de rayons X. La structure depend des traitements thermiques et mecaniques subis par les echantillons ainsi que la temperature d'observation. La diffusion centrale due a l'existence d'heterogeneites de la matiere a l'echelle 100-200 Angstrom est lie a la presence des deux phases amorphe et cristallisee. Le polyethylene etire comporte une succession plus ou moins reguliere de domaines ordonnes et desordonnes. Le polyethylene relaxe a une structure de recristallisation precedee d'une 'amorphisation'. (auteur)

  15. Damage caused to houses and equipment by underground nuclear explosions; Degats dus aux explosions nucleaires souterraines sur les habitations et les equipements

    Energy Technology Data Exchange (ETDEWEB)

    Delort, F; Guerrini, C [Commissariat a l' Energie Atomique, Bruyeres-le-Chatel (France). Centre d' Etudes

    1969-07-01

    A description is given of the damaged caused to various structures, buildings, houses, mechanical equipment and electrical equipment by underground nuclear explosions in granite. For each type of equipment or building are given the limiting distances for a given degree of damage. These distances have been related to a parameter characterizing the movement of the medium; it is thus possible to generalize the results obtained in granite, for different media. The problem of estimating the damage caused at a greater distance from the explosion is considered. (authors) [French] Les degats sur diverses structures, constructions, habitations, equipements mecaniques et materiels electriques provoques par des explosions nucleaires souterraines dans le granite sont decrits. On a indique pour chaque type de materiel ou de construction, les distances limites correspondant a un degre de gravite de dommage observe. Ces distances ont ete reliees a un parametre caracterisant le mouvement du milieu, permettant ainsi de generaliser les resultats obtenus dans le granite, a differents milieux. Le probleme de la prevision des degats en zone lointaine a ete aborde. (auteurs)

  16. Recording {gamma} spectrometer with elimination of compton background; Spectrographe {gamma} enregistreur avec elimination du bruit de fond compton

    Energy Technology Data Exchange (ETDEWEB)

    Julliot, C [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    This instrument, derived from the recording {gamma} spectrograph, gives better definition of photoelectric peaks by elimination of pulses caused by {gamma} photons incompletely absorbed in the scintillator (Compton effect). This system uses an original method devised by Peirson: the spectrum, devoid of photoelectric peak, supplied by a detector equipped with an anthracene scintillator, is cut off from the spectrum provided by a conventional detector equipped with a Nal (T1) scintillator. The regulation of the mechanical system, detector support and source allows the detection yields to be adjusted. The electronic system is identical in presentation with that of the recording spectrograph. (author) [French] Cet appareil derive du spectrographe {gamma} enregistreur permet d'obtenir une meilleure definition des pics photoelectriques, par elimination des impulsions provenant des photons {gamma} incompletement absorbes dans le scintillateur (effet Compton). Cet ensemble met en oeuvre une methode originale due a Peirson: le spectre, depourvu de pic photoelectrique, fourni par un detecteur, equipe avec un scintillateur d'anthracene, est retranche du spectre donne par un detecteur classique, equipe avec un scintillateur de NaI (T1). Le reglage de l'ensemble mecanique, support des detecteurs et de la source, permet d'ajuster les rendements de detection. L'ensemble electronique se presente sous un aspect identique a celui du spectrographe enregistreur. (auteur)

  17. Damping efficiency of the Tchamwa-Wielgosz explicit dissipative scheme under instantaneous loading conditions

    Science.gov (United States)

    Mahéo, Laurent; Grolleau, Vincent; Rio, Gérard

    2009-11-01

    To deal with dynamic and wave propagation problems, dissipative methods are often used to reduce the effects of the spurious oscillations induced by the spatial and time discretization procedures. Among the many dissipative methods available, the Tchamwa-Wielgosz (TW) explicit scheme is particularly useful because it damps out the spurious oscillations occurring in the highest frequency domain. The theoretical study performed here shows that the TW scheme is decentered to the right, and that the damping can be attributed to a nodal displacement perturbation. The FEM study carried out using instantaneous 1-D and 3-D compression loads shows that it is useful to display the damping versus the number of time steps in order to obtain a constant damping efficiency whatever the size of element used for the regular meshing. A study on the responses obtained with irregular meshes shows that the TW scheme is only slightly sensitive to the spatial discretization procedure used. To cite this article: L. Mahéo et al., C. R. Mecanique 337 (2009).

  18. Production of nuclear graphite in France; Production de graphite nucleaire en France

    Energy Technology Data Exchange (ETDEWEB)

    Legendre, P; Mondet, L [Societe Pechiney, 74 - Chedde (France); Arragon, Ph; Cornuault, P; Gueron, J; Hering, H [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1955-07-01

    The graphite intended for the construction of the reactors is obtained by the usual process: confection of a cake from coke of oil and tar, cooked (in a electric oven) then the product of cook is graphitized, also by electric heating. The use of the air transportation and the control of conditions cooking and graphitization have permitted to increase the nuclear graphite production as well as to better control their physical and mechanical properties and to reduce to the minimum the unwanted stains. (M.B.) [French] Le graphite destine a la construction des reacteurs est obtenu par le procede usuel: confection d'une pate a partir de coke de petrole et de brai, cuisson de cette pate (au four electrique) puis graphitation du produit cuit, egalement par chauffage electrique. L'usage du transport pneumatique et le controle des conditions cuisson et de graphitation ont permit d'augmenter la production de graphite nucleaire ainsi que de mieux controler ses proprietes physiques et mecaniques et de reduire au minimum les souillures accidentelles. (M.B.)

  19. Methods for determining thermal stresses values. Some examples relating to nuclear reactors; Methodes de determination des contraintes thermiques. Quelques exemples d'application aux reacteurs

    Energy Technology Data Exchange (ETDEWEB)

    Bernard, J; Gautier, A [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Peres, A [Israel Institute of Technology, Dept. of Nuclear Science Technion (Israel)

    1958-07-01

    As modern techniques develop more elaborate machines, and make their way towards higher and higher temperatures and pressures, the thermal stresses become a matter of major importance in the design of mechanical structures. In the first part of this paper, the authors examine the problem from a theoretical standpoint, and try to evaluate the aptitude and limitation of mathematical techniques to attain the quantitative values of thermal stresses. This paper deals mainly with the experimental methods to measure thermal stresses. The authors show some examples relating to nuclear reactors. (author)Fren. [French] Au fur et a mesure que la technique moderne developpe des machines plus poussees et s'oriente vers des temperatures et des pressions toujours plus elevees, les contraintes thermiques deviennent un facteur d'importance capitale dans le calcul des structures mecaniques. Les auteurs examinent d'abord l'aspect theorique du probleme, ainsi que l'aptitude et les limites du calcul pour exprimer quantitativement la valeur des contraintes thermiques. Les auteurs exposent principalement, ensuite, les methodes experimentales qui permettent de mesurer ces contraintes, et illustrent cet expose de quelques exemples relatifs aux installations nucleaires. (auteur)

  20. Building of a facility for the handling of kilo-curie amounts of gamma emitters; Construction d'une enceinte pour la manipulation d'un kilocurie d'emetteurs gamma

    Energy Technology Data Exchange (ETDEWEB)

    Germond, Ph [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    A hot cell designed to handle up to 1000 curies of cobalt-60 has been built in a preexisting shielded room, in order to make optimum use of available space. Heavy containers can be rolled in or out of the cell. Handling performed with two manipulators designed and made by French manufacturers, one of them is pneumatically operated and the other one is mechanical. The general shape of the facility is that of an L. (author) [French] Une cellule chaude, concue pour manipuler jusqu'a 1000 curies de cobalt-60, a ete construite dans un local blinde deja existant, de facon a employer au mieux l'espace disponible. On peut introduire et sortir de lourds containers, dans cette cellule. Ces manipulations sont faites a l'aide de deux manipulateurs concus et realises en France; l'un d'eux est pneumatique et l'autre mecanique. L'ensemble de la cellule a la forme d'un L. (auteur)

  1. CFD Code Validation against Stratified Air-Water Flow Experimental Data

    International Nuclear Information System (INIS)

    Terzuoli, F.; Galassi, M.C.; Mazzini, D.; D'Auria, F.

    2008-01-01

    Pressurized thermal shock (PTS) modelling has been identified as one of the most important industrial needs related to nuclear reactor safety. A severe PTS scenario limiting the reactor pressure vessel (RPV) lifetime is the cold water emergency core cooling (ECC) injection into the cold leg during a loss of coolant accident (LOCA). Since it represents a big challenge for numerical simulations, this scenario was selected within the European Platform for Nuclear Reactor Simulations (NURESIM) Integrated Project as a reference two-phase problem for computational fluid dynamics (CFDs) code validation. This paper presents a CFD analysis of a stratified air-water flow experimental investigation performed at the Institut de Mecanique des Fluides de Toulouse in 1985, which shares some common physical features with the ECC injection in PWR cold leg. Numerical simulations have been carried out with two commercial codes (Fluent and Ansys CFX), and a research code (NEPTUNE CFD). The aim of this work, carried out at the University of Pisa within the NURESIM IP, is to validate the free surface flow model implemented in the codes against experimental data, and to perform code-to-code benchmarking. Obtained results suggest the relevance of three-dimensional effects and stress the importance of a suitable interface drag modelling

  2. High-repetition-rate hydrogen chamber: Preliminary studies; Chambre a hydrogene a haut taux de repetition: Etudes preliminaires

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1967-01-01

    This report is a conclusion to the tests realised with an experimental bubbles chamber in view to study the possibilities to increase the repetition rate. The more important parameters (the evolution of the bubbles, the expansion system) are considered in a theoretical way. Then the hardware is described. To end, experimental results are compared with the first evaluations. The calculations and the experimentation are against an oscillation system for the expansion. A system with a locking is to he considered. (authors) [French] Ce rapport est une conclusion aux essais realises avec une chambre a bulles experimentale en vue d'etudier les possibilites d'accroitre les taux de repetition. Les parametres les plus importants (evolution des bulles, mecanique de la detente) sont etudies par voie theorique. Puis l'appareillage est decrit. Enfin, les resultats experimentaux sont compares aux evaluations donnees au debut. Ces calculs et cette experimentation ne sont pas en faveur d'un systeme oscillant pour la detente et il faut envisager un systeme avec verrouillage. (auteurs)

  3. Analytical development of disturbed matrix eigenvalue problem applied to mixed convection stability analysis in Darcy media

    Science.gov (United States)

    Hamed, Haikel Ben; Bennacer, Rachid

    2008-08-01

    This work consists in evaluating algebraically and numerically the influence of a disturbance on the spectral values of a diagonalizable matrix. Thus, two approaches will be possible; to use the theorem of disturbances of a matrix depending on a parameter, due to Lidskii and primarily based on the structure of Jordan of the no disturbed matrix. The second approach consists in factorizing the matrix system, and then carrying out a numerical calculation of the roots of the disturbances matrix characteristic polynomial. This problem can be a standard model in the equations of the continuous media mechanics. During this work, we chose to use the second approach and in order to illustrate the application, we choose the Rayleigh-Bénard problem in Darcy media, disturbed by a filtering through flow. The matrix form of the problem is calculated starting from a linear stability analysis by a finite elements method. We show that it is possible to break up the general phenomenon into other elementary ones described respectively by a disturbed matrix and a disturbance. A good agreement between the two methods was seen. To cite this article: H.B. Hamed, R. Bennacer, C. R. Mecanique 336 (2008).

  4. ASTRID: A 3D Eulerian software for subcooled boiling modelling - comparison with experimental results in tubes and annuli

    Energy Technology Data Exchange (ETDEWEB)

    Briere, E.; Larrauri, D.; Olive, J. [Electricite de France, Chatou (France)

    1995-09-01

    For about four years, Electricite de France has been developing a 3-D computer code for the Eulerian simulation of two-phase flows. This code, named ASTRID, is based on the six-equation two-fluid model. Boiling water flows, such as those encountered in nuclear reactors, are among the main applications of ASTRID. In order to provide ASTRID with closure laws and boundary conditions suitable for boiling flows, a boiling model has been developed by EDF and the Institut de Mecanique des Fluides de Toulouse. In the fluid, the heat and mass transfer between a bubble and the liquid is being modelled. At the heating wall, the incipient boiling point is determined according to Hsu`s criterion and the boiling heat flux is split into three additive terms: a convective term, a quenching term and a vaporisation term. This model uses several correlations. EDF`s program in boiling two-phase flows also includes experimental studies, some of which are performed in collaboration with other laboratories. Refrigerant subcooled boiling both in tubular (DEBORA experiment, CEN Grenoble) and in annular geometry (Arizona State University Experiment) have been computed with ASTRID. The simulations show the satisfactory results already obtained on void fraction and liquid temperature. Ways of improvement of the model are drawn especially on the dynamical part.

  5. Optimisation des proprietes fonctionnelles des alliages a memoire de forme suite a l'application de traitements thermomecaniques

    Science.gov (United States)

    Demers, Vincent

    L'objectif de ce projet est de determiner les conditions de laminage et la temperature de traitement thermique maximisant les proprietes fonctionnelles de l'alliage a memoire de forme Ti-Ni. Les specimens sont caracterises par des mesures de calorimetrie, de microscopie optique, de gene ration de contrainte, de deformation recuperable et des essais mecaniques. Pour un cycle unique, l'utilisation d'un taux d'ecrouissage e=1.5 obtenu avec l'application d'une force de tension FT = 0.1sigma y et d'une huile minerale resulte en un echantillon droit, sans microfissure et qui apres un recuit a 400°C, produit un materiau nanostructure manifestant des proprietes fonctionnelles deux fois plus grandes que le meme materiau ayant une structure polygonisee. Pour des cycles repetes, les memes conditions de laminage sont valables mais le niveau de deformation optimal est situe entre e=0.75-2, et depend particulierement du mode de sollicitation, du niveau de stabilisation et du nombre de cycles a la rupture requis par l'application.

  6. Contribution to the study of the microstructure of uranium dioxide (1962); Contribution a l'etude de la microstructure du dioxyde d'uranium (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Porneuf, A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1960-05-15

    The microstructure of sintered uranium dioxide is studied in relation with several parameters, specially the sintering temperatures and atmospheres. The external surface and the internal microstructure of the sintered are examined, using fractography and ceramography. Various techniques for preparing surfaces (mechanical and electrolytic polishing) and for revealing the structure (chemical and anodic attack, ionic bombardment oxidation) have been experienced and compared. Patterns similar to those revealed in metals and probably related with interactions between dislocations and vacancies have been observed. (author) [French] La microstructure de frittes d'oxyde d'uranium est etudiee en fonction de divers parametres, en particulier de la temperature et de l'atmosphere de frittage, par examen de la surface externe des frittes, puis de leur microstructure interne (fractographie, ceramographie). Differentes techniques de preparation des surfaces (polissage mecanique ou electrolytique) et de revelation de la structure (attaque chimique ou anodique, bombardement ionique, oxydation preferentielle) ont ete experimentees et comparees. Des figures comparables a celles revelees dans les metaux et liees probablement a des interactions entre dislocations et lacunes ont ete observees. (auteur)

  7. Physics of phenomena in the zone close to an underground nuclear explosion; Physique des phenomenes en zone proche des explosions nucleaires souterraines

    Energy Technology Data Exchange (ETDEWEB)

    Maury, J.; Levret, C. [Commissariat a l' Energie Atomique, Bruyeres-le-Chatel (France). Centre d' Etudes

    1969-07-01

    After a description of the phenomenology of underground explosions, the basic laws governing the propagation in the ground of the energy produced by the explosion are given. The reports considers hydrodynamics, the mechanics of solids, the equations of state for solids and gases in the case of very high and medium pressures, and the dynamical strength of solids. These various elements make it possible to draw up a system of equations which define completely the changes with time of the shock-wave produced in the ground by the explosion. (authors) [French] Apres une description de la phenomenologie des explosions souterraines, on expose les lois fondamentales regissant la propagation dans le sol de l'energie degagee par l'explosion. L'expose comprend des developpements sur l'hydrodynamique, la mecanique des solides, les equations d'etat des solides et des gaz, aux tres fortes et moyennes pressions, et sur la resistance dynamique des solides. Ces differents elements permettent d'ecrire un systeme d'equations qui definissent completement l'evolution dans le temps de l'onde de choc emise dans le sol par l'explosion. (auteurs)

  8. Study and realization of an electron linear accelerator. Dynamics of accelerated electrons; Etude et realisation d'un accelerateur lineaire d'electrons. Dynamique des electrons acceleres

    Energy Technology Data Exchange (ETDEWEB)

    Bernard, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-04-01

    The theoretical characteristics of the electron linear accelerator are: 30 MeV for the energy W{sub S} and 250 mA for the peak current I{sub c}. The main utilization is the intense production of fast neutrons by the reactions ({gamma},n) and ({gamma},f) induced in a target of natural uranium by the accelerated electrons. In the first part of the thesis, relative to the study and the realization of the accelerator, a new equation of dispersion is established analytically when the guide is loaded with round-edged irises. The relation is compared with the equation established by CHU and Hansen, WALKINSHAW, KVASIL in the case of a guide loaded with flat-edged irises. The experimental and theoretical curves of dispersion are compared. The accuracy of every relation of dispersion is estimated. The second part of the thesis is relative to the theoretical study of the electrons dynamics in the guide; it allows the derivation of the parameters of the beam: dispersion of phase, energy, dispersion of energy and the relation W{sub S} = f (I{sub c}). The results relative to the first experiments are given and compared with the theoretical expectations. (author) [French] Les caracteristiques nominales theoriques de l'accelerateur lineaire d'electrons sont: 30 MeV pour l'energie W{sub S} et 250 mA pour le courant de crete I{sub c}. L'utilisation principale envisagee est la production de neutrons rapides par les reactions ({gamma},n) et ({gamma},f) induites dans une cible d'uranium naturel par les electrons acceleres. Dans la premiere partie de la these relative a l'elude et a la realisation de l'accelerateur, une nouvelle equation de dispersion (ou equation aux frequences) est etablie analytiquement pour un guide charge par des iris a bord rond. Cette relation est comparee a celles etablies par CHU et HANSEN, WALKINSHAW, KVASIL dans le cas du guide charge par des iris a bord plat. On compare les courbes de dispersion theoriques et experimentales et on evalue la precision de

  9. Analytical Solutions and Optimization of the Exo-Irreversible Schmidt Cycle with Imperfect Regeneration for the 3 Classical Types of Stirling Engine Solutions analytiques et optimisation du cycle de Schmidt irréversible à régénération imparfaite appliquées aux 3 types classiques de moteur Stirling

    Directory of Open Access Journals (Sweden)

    Rochelle P.

    2011-11-01

    optimisation ajustables sont le rapport volumetrique de compression, les rapports de volume mort, le dephasage des volumes balayes, les caracteristiques du gaz, le rapport des conductances “chaude” et “froide” et l’efficacite du regenerateur. Des expressions analytiques nouvelles pour les caracteristiques de fonctionnement du moteur : puissance, travail, rendement, pression moyenne, vitesse maximale, sont etablies et quelques nombres de references adimensionnels ou pas sont presentes ainsi que des exemples d’optimisation de la puissance en fonction de la vitesse reduite (adimensionnelle, du rapport des volumes et de l’angle de dephasage.

  10. Background noise in amplifiers of pulse ionization rooms; Le bruit de fond dans les amplificateurs de chambre d'ionisation a impulsions

    Energy Technology Data Exchange (ETDEWEB)

    Valladas, G; Leveque, A [Commissariat a l' Energie Atomique, Lab. du Fort de Chatillon, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1952-07-01

    The accuracy on the charge measures liberated in a pulse ionization room is limited by the background noise inherent to the used amplifier. Firstly we remind briefly the main features of the signal collected on the electrode collector of the room and the background noise, then the theory of Milatz and Keller. This theory establishes the existence of an absolute limit on the precision of the measures, characteristic of the preamplifier tube and permits its calculation. We define the transient answer of an ideal amplifier allowing effectively this precision. We propose a convenient circuit having this answer and we compare with the usually used circuits. In the case the method of Scherr and Peterson, we show that a supplementary condition render the previous theory insufficient. We calculate the optimum transient response in this case and the value of the limit of precision who ensues. We consider some simple circuits and compare to this limit the precision that they permit to get. (author) [French] La precision sur les mesures de charges liberees dans une chambre d'ionisation a impulsions est limitee par le bruit de fond inherent a l'amplificateur utilise. Nous rappelons brievement tout d'abord les caracteristiques principales du signal recueilli sur l'electrode collectrice de la chambre et du bruit de fond, puis la theorie de Milatz et Keller. Cette theorie etablit l'existence d'une limite absolue sur la precision des mesures, caracteristique du tube preamplificateur, et permet son calcul. Nous definissons la reponse transitoire de l'amplificateur ideal permettant d'attendre effectivement cette precision. Nous proposons un circuit pratique ayant cette reponse et nous lui comparons les circuits habituellement utilises. Dans le cas ou l'on emploie la methode de Scherr et Peterson, nous montrons qu'une condition supplementaire s'introduit rendant la theorie precedente insuffisante. Nous calculons donc la reponse transitoire optimum dans ce cas et la valeur de la

  11. Electrolytic dissociation of NH{sub 2}K in liquid ammonia; Dissociation electrolytique de NH{sub 2}K dans NH{sub 3} liquide

    Energy Technology Data Exchange (ETDEWEB)

    Botter, F [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    By assuming the Debye and Huckel approximation giving the activity coefficient and the Onsager relationship linking the conductivity and infinite dilution conductivity of an electrolyte, it has been possible using the available literature data and the electrical conductivity measurements carried out for this purpose, to calculate certain typical parameters of the dissociation of potassium amide in liquid ammonia in the temperature range of -77 deg. C to -33.5 deg. C: degree of dissociation, mean activity coefficient of the ions NH{sub 2}{sup -} and K{sup +}, and the mean activity of these ions. (author) [French] En admettant l'approximation de Debye et Huckel donnant le coefficient d'activite et la relation d'Onsager reliant conductivite et conductivite a dilution infinie d'un electrolyte, on a, en se basant sur les donnees bibliographiques disponibles et des mesures de conductivite electrique effectuees a cette fin, determine par un calcul, certains parametres caracteristiques de la dissociation de l'amidure de potassium dans l'ammoniac liquide dans un domaine de temperature de -77 deg. C a -33,5 deg. C: degre de dissociation, coefficient d'activite moyen des ions NH{sub 2}{sup -} et K{sup +} et activite moyenne de ces ions. (auteur)

  12. Stability of plasmas obtained in E.P.P.E; Stabilite des plasmas obtenus dans E. P. P. E

    Energy Technology Data Exchange (ETDEWEB)

    Adam, J; Rebut, P H; Torossian, A [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1964-07-01

    The stability results obtained on Mest have been extended on a machine ten times more powerful: EppE. A plasma stable during its whole confinement time has been observed. This confinement time seems to be limited by the resistive diffusion of the magnetic fields through the plasma. The main characteristics of this plasma are: Time of confinement: 200 {mu}s; T{sub e} {approx} T{sub i}: 40 eV; {beta} = 8*{pi}*k*T*n{sub e}/B{sup 2}: 8%; n{sub e}: 2.5*10{sup 15}/cm{sup 3}. (authors) [French] Les resultats sur la stabilite obtenus dans Mest ont ete developpes dans une machine dix fois plus puissante: EppE. Un plasma stable pendant toute la duree de son confinement a ete observe et la limitation de ce temps est bien expliquee par la diffusion resistive des champs magnetiques a travers le plasma. Les principales caracteristiques du plasma d'EppE sont: Temps de confinement: 200 {mu}s; T{sub e} {approx} T{sub i}: 40 eV; {beta} 8*{pi}*k*T*n{sub e}/B{sup 2}: 8%; n{sub e}: 2.5*10{sup 15}/cm{sup 3}.

  13. Des proprietes de l'etat normal du modele de Hubbard bidimensionnel

    Science.gov (United States)

    Lemay, Francois

    Depuis leur decouverte, les etudes experimentales ont demontre que les supra-conducteurs a haute temperature ont une phase normale tres etrange. Les proprietes de ces materiaux ne sont pas bien decrites par la theorie du liquide de Fermi. Le modele de Hubbard bidimensionnel, bien qu'il ne soit pas encore resolu, est toujours considere comme un candidat pour expliquer la physique de ces composes. Dans cet ouvrage, nous mettons en evidence plusieurs proprietes electroniques du modele qui sont incompatibles avec l'existence de quasi-particules. Nous montrons notamment que la susceptibilite des electrons libres sur reseau contient des singularites logarithmiques qui influencent de facon determinante les proprietes de la self-energie a basse frequence. Ces singularites sont responsables de la destruction des quasi-particules. En l'absence de fluctuations antiferromagnetiques, elles sont aussi responsables de l'existence d'un petit pseudogap dans le poids spectral au niveau de Fermi. Les proprietes du modele sont egalement etudiees pour une surface de Fermi similaire a celle des supraconducteurs a haute temperature. Un parallele est etabli entre certaines caracteristiques du modele et celles de ces materiaux.

  14. A new class of medicament: radioactivity isotopes (1962); Une nouvelle classe de medicaments: les isotopes radioactifs (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, Y. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1962-07-01

    Very many radioelement are used in medicine, either for diagnosis or as therapeutics. The development of medicine has entailed an increase in the number of application of radioactive isotopes. Firstly used in the form of simple inorganic molecules for diagnosis or as anticancer therapeutics, radioelements are now used for labelling organic molecules, allowing functional specific studies of any kind of nature. Their production is made difficult by their radio-active properties. Their pharmaceutical properties, determined by tests and controls, depend either from radiochemistry and from medicine. The author reminds, in this report, the methods for the preparation and analysis, and set out the medical application. (author) [French] De tres nombreux radioelements trouvent une application en medecine humaine, soit dans le diagnostic, soit en therapeutique. L'evolution de la medecine entraine un accroissement du champ d'application des isotopes radioactifs. D'abord utilises sous forme de molecules minerales simples, pour les diagnostics ou des therapeutiques anticancereuses, les radioelements sont maintenant introduits dans des molecules organiques qui permettent des etudes fonctionnelles specifiques de toute nature. Leur fabrication est compliquee par leurs proprietes radioactives. Leurs caracteristiques pharmaceutiques determinees par des essais et controles, sont liees d'une part a la radiochimie, d'autre part a la medecine. L'auteur rappelle, dans cet expose, les methodes de preparation et d'analyse et aborde les applications medicales. (auteur)

  15. The control equipment of the Melusine II reactor; L'equipement de controle du reacteur Melusine II

    Energy Technology Data Exchange (ETDEWEB)

    Cordelle, M; Delcroix, V; Denis, P; Gariod, R

    1963-07-01

    Melusine II, low-power reactor, used for the study of Siloe core has diverged at the CEA Grenoble, the 23. May 1962; its monitoring board studied and carried out in this center is the first in France to be entirely transistorized. The first months of running have justified the hope put in the new electronics to improve the stability and the safety of running. The article describes the design of the control and gives the main characteristics of the measurement chains and of the actions on reactivity. (O.M.) [French] Melusine II, reacteur de faible puissance destine a l'etude du coeur de Siloe a diverge au Centre d'Etudes Nucleaires de Grenoble, le 23 mai 1962, son tableau de controle etudie et realise dans ce Centre est le premier en France a etre entierement transistorise. Les premiers mois de fonctionnement ont justifie l'espoir mis dans la nouvelle electronique pour ameliorer la stabilite et la surete de fonctionnement. L'article decrit la conception du controle et donne les principales caracteristiques des chaines de mesure et des actions sur la reactivite. (auteurs)

  16. A new class of medicament: radioactivity isotopes (1962); Une nouvelle classe de medicaments: les isotopes radioactifs (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, Y [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1962-07-01

    Very many radioelement are used in medicine, either for diagnosis or as therapeutics. The development of medicine has entailed an increase in the number of application of radioactive isotopes. Firstly used in the form of simple inorganic molecules for diagnosis or as anticancer therapeutics, radioelements are now used for labelling organic molecules, allowing functional specific studies of any kind of nature. Their production is made difficult by their radio-active properties. Their pharmaceutical properties, determined by tests and controls, depend either from radiochemistry and from medicine. The author reminds, in this report, the methods for the preparation and analysis, and set out the medical application. (author) [French] De tres nombreux radioelements trouvent une application en medecine humaine, soit dans le diagnostic, soit en therapeutique. L'evolution de la medecine entraine un accroissement du champ d'application des isotopes radioactifs. D'abord utilises sous forme de molecules minerales simples, pour les diagnostics ou des therapeutiques anticancereuses, les radioelements sont maintenant introduits dans des molecules organiques qui permettent des etudes fonctionnelles specifiques de toute nature. Leur fabrication est compliquee par leurs proprietes radioactives. Leurs caracteristiques pharmaceutiques determinees par des essais et controles, sont liees d'une part a la radiochimie, d'autre part a la medecine. L'auteur rappelle, dans cet expose, les methodes de preparation et d'analyse et aborde les applications medicales. (auteur)

  17. Radio-active pollution near natural uranium-graphite-gas reactors; La pollution radioactive aupres des piles uranium naturel - graphite - gaz

    Energy Technology Data Exchange (ETDEWEB)

    Chassany, J.; Pouthier, J.; Delmar, J. [Commissariat a l' Energie Atomique, Chusclan (France). Centre de Production de Plutonium de Marcoule

    1967-07-01

    The results of numerous evaluations of the contamination are given: - Reactors in operation during maintenance operations. - Reactors shut-down during typical repair operations (coolants, exchangers, interior of the vessel, etc. ) - Following incidents on the cooling circuit and can-rupture. They show that, except in particular cases, it is the activation products which dominate. Furthermore, after ten years operation, the points at which contamination liable to emit strong doses accumulates are very localized and the individual protective equipment has not had to be reinforced. (authors) [French] Les resultats de nombreuses evaluations de la contamination sont donnes: - Piles en marche pendant les operations d'entretien - Piles a l'arret au cours des chantiers caracteristiques (refrigerants, echangeurs, interieur du caisson, etc.) - A la suite d'incidents sur le circuit de refroidissement et de rupture de gaine. Ils montrent que, sauf cas particulier, ce sont essentiellement les produits d'activation qui dominent. Par ailleurs apres 10 ans de fonctionnement, les points d'accumulation de la contamination susceptibles de delivrer des debits de dose importants restent tres localises et les moyens de protection individuels utilises n'ont pas du etre renforces. (auteurs)

  18. Local energy policies: Planning devices and coaching tools - Example of the French case; Politiques energetiques locales: Dispositifs de planification et outils d'accompagnement - Exemple du cas francais

    Energy Technology Data Exchange (ETDEWEB)

    Chanard, Camille; de Sede-Marceau, Marie-Helene

    2010-09-15

    Collectivities traditionally have multiple responsibilities linked to energy. They act directly on the energy chain (production-distribution-consumption) through their heritage, but also on the tripych space-environment-society, in particular through their planning choices. Hence, all the public policies are concerned by the energy theme. However, collectivities seem to suffer from an information deficit, both on planning devices that can be mobilized and on the territory features. This article proposes to realise an overview tour of the coaching tools that can be used by the French territories collectivities to build efficient energy policies. [French] Les collectivites ont traditionnellement des responsabilites multiples en lien avec l'energie. Elles agissent directement sur la chaine energetique (production-distribution-consommation) a travers leur patrimoine, mais aussi sur le triptyque espace-environnement-societe, en particulier a travers leurs choix d'amenagement. Ainsi, toutes les politiques publiques sont concernees par la thematique ' energie '. Cependant, les collectivites semblent souffrir d'un deficit d'information, tant sur les dispositifs de planification pouvant etre mobilises que sur les caracteristiques du territoire. Cet article propose de realiser un tour d'horizon de l'ensemble des outils d'accompagnements pouvant etre mobilises par les collectivites territoriales francaises pour construire des politiques energetiques efficaces.

  19. Studies of plutonium-iron and uranium-plutonium-iron alloys; Etudes d'alliages plutonium-fer et d'alliages uranium-plutonium-fer

    Energy Technology Data Exchange (ETDEWEB)

    Avivi, Ehud [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1964-01-15

    We study the plutonium-iron system, by means of dilatometry, X rays and metallography, especially in the domain between PuFe{sub 2} and Fe. We determine the solubilities of Fe in PuFe{sub 2} and of Pu in Fe. We show the presence of an hexagonal PuFe{sub 2} phase and we propose a modification in the Pu-Fe phase diagram. Some low iron concentration U-Pu-Fe alloys have also been investigated. We characterise the different phases. We confirm that adding some iron lowers the quantity of the zeta U-Pu phase. We emphasize some characteristics of the alloys having the global concentration (U, Pu){sub 6} Fe. (authors) [French] On etudie par dilatometrie, rayons X et micrographie le systeme plutonium-fer, principalement dans la region comprise entre PuFe{sub 2} et Fe, On determine les solubilites du fer dans PuFe{sub 2}, et de Pu dans Fe. On met en evidence une phase PuFe{sub 2} hexagonale et on propose une modification du diagramme d'equilibre Pu-Fe. Certains alliages U-Pu-Fe a faibles concentrations en fer sont egalement etudies. On caracterise les phases en presence. On confirme que l'addition de fer diminue rapidement la quantite de phase U-Pu zeta. Enfin on revele certaines caracteristiques des alliages de composition globale (U, Pu){sub 6} Fe. (auteurs)

  20. Determination of local boiling in light water reactors by correlation of the neutron noise; Determination de l'ebullition locale dans les reacteurs a eau legere par correlation du bruit neutronique

    Energy Technology Data Exchange (ETDEWEB)

    Zwingelstein, G [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1968-07-01

    The power limit of swimming-pool type reactors depends on the phenomenon of the appearance of burn-out. In order to determine this limit we have attempted to detect the local boiling which usually occurs before the burn out. Local boiling has been simulated by an electrically heated plate placed in the core of the reactor Siloette. The study of local boiling, which is based on the properties of the correlation functions for the neutron noise of detectors placed in the core, shows that a privileged frequency occurs in the power spectrum of the noise. It is intended in the future to determine the influence of various parameters on this characteristic frequency. (author) [French] La limitation de la puissance des reacteurs nucleaires de type piscine est due au phenomene d'apparition de 'burn out'. Pour determiner cette limitation, nous nous sommes proposes dans ce rapport de detecter l'ebullition locale qui apparait generalement avant le 'burn out'. L'ebullition locale a ete simulee par une plaque chauffee electriquement et placee dans le coeur du reacteur SILOETTE. L'etude de l'ebullition locale, qui est basee sur les proprietes des fonctions de correlation du bruit neutronique de detecteurs places clans le coeur, fait apparaitre une frequence privilegiee dans le spectre de puissance du bruit. On envisage dans l'avenir, de determiner l'influence des divers parametres sur cette frequence caracteristique. (auteur)

  1. The synthesis and spectroscopic study of stable free radicals related to piperidine-n-oxyl, including a stable bi-radical; Syntheses et etudes spectroscopiques de radicaux libres piperidiniques et d'un biradical stable, du type nitroxyde

    Energy Technology Data Exchange (ETDEWEB)

    Briere, R [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires, Laboratoire de chimie organique physique

    1967-06-01

    A new synthesis of di-tert-butyl nitroxide using the reaction between tert-butyl magnesium chloride and nitro-tert-butane is presented in the first section. Synthesis and investigation of stable free piperidine-N-oxyl radicals are described in the second section. All these nitroxides have been characterised by their I. R., U. V. and E. P. R. absorption spectra. The final section contains a description of the synthesis of a stable bi-radical of the nitroxide type by condensation of 2,2, 6, 6-tetramethyl-piperid-4-one-l-oxyl with hydrazine. (author) [French] La premiere partie expose une nouvelle methode de synthase du di-t-butyl nitroxyde, par action d'halogenures de t-butyl magnesium sur le nitro-t-butane (Rdt maximum 45 pour cert, purete 86 pour cent). Une etude de radicaux. libres stables pipericliniques est faite dans une seconde partie. Ces composes sont obtenus par oxydation de derives de la triacetonamine. Les caracteristiques spectroscopiques ultra-violette, infra-rouge, et paramagnetique electronique de ces radicaux sont donnees. La grande inertie chimique du groupement nitroxyde a permis la syn-these d'un biradical stable par formation d'azine d'une cetone radicalaire, ce qui fait 1'objet de la troisieme partie. (auteur)

  2. Syntheses and study of pyrrolidinic nitroxide free radicals. Preparation of a nitroxide-type stable bi-radical; Synthese et etudes de radicaux libres nitroxydes pyrrolidiniques. Preparation d'un biradical stable du type nitroxyde

    Energy Technology Data Exchange (ETDEWEB)

    Dupeyre, R M [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires, Laboratoire de chimie organique physique

    1967-12-01

    Syntheses and study of pyrrolidinic nitroxide free radicals: These radicals are obtained by oxidation, with hydrogen peroxide, of pyrrolidinic amines prepared from triacetonamine by ring contraction. The U. V,, I. R, and E.P.R. spectral characteristics have been determined. The oxidation of these amines with hydrogen peroxide has led also to rupture of the pentagonal ring; some of the decomposition products have been identified. The high chemical stability of the nitroxide group has made it possible to synthesize and study a stable bi-radical. (author) [French] Syntheses et etudes de radicaux libres nitroxydes pyrrolidiniques: Ces radicaux sont obtenus par oxydation l'eau oxygenee d'amines pyrrolidiniques preparees a partir de la triacetonamine par contraction de cycle. Les caracteristiques spectroscopiques ultra-violettes, infra-rouge et resonance paramagnetique sont determinees. Cependant, 1'oxydation de ces amines a l'eau oxygenee a entraine la coupure du cycle pentagonal et identification de certaines substances de decomposition obtenues. La grande stabilite chimique de groupement nitroxyde a permis la synthese et l'etude d'un biradical stable. (auteur)

  3. Sintering of beryllium oxide; Frittage de l'oxyde de beryllium

    Energy Technology Data Exchange (ETDEWEB)

    Caillat, R; Pointud, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1955-07-01

    This study had for origin to find a process permitting to manufacture bricks of beryllium oxide of pure nuclear grade, with a density as elevated as possible and with standardized shape. The sintering under load was the technique kept for the manufacture of the bricks. Because of the important toxicity of the beryllium oxide, the general features for the preliminary study of the sintering, have been determined while using alumina. The obtained results will be able to act as general indication for ulterior studies with sintering under load. (M.B.) [French] Cette etude a eu pour origine la recherche d'un procede permettant de fabriquer industriellement des briques d'oxyde de beryllium nucleaireraent pures, de densite aussi elevee que possible et de forme standardisee. Le frittage sous charge fut la technique retenue pour la fabrication des briques. En raison de la grande toxicite de l'oxyde de beryllium, les caracteristiques generales du frittage, pour l'etude preliminaire, ont ete determine en utilisant de l'alumine. Les resultats obtenus pourront servir d'indication generale pour des etudes ulterieurs avec frittage sous charge. (M.B.)

  4. The design of coils for the production of high homogeneous fields; Calcul des bobinages pour la production de champs magnetiques tres homogenes

    Energy Technology Data Exchange (ETDEWEB)

    Desportes, H [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    The discovery of type II superconductors has considerably increased the possibilities of air-core coils, in particular with regard to the production of high homogeneous fields. The design of such magnets,calls for elaborate calculations which, in practise, can only be carried out on computers. The present report describes a complete set of programs for the calculation, in the case of cylindrical systems, of the magnetic field components at any point, the lines of flux, the forces, the self and mutual inductances, as well as the design of compensated coils for the production of high homogeneous fields. These programs have been employed for the calculation of two magnets which are described in detail. (author) [French] L'interet des bobines sans fer s'est considerablement accru depuis l'apparition recente des supraconducteurs de la deuxieme espece, en particulier pour la realisation d'aimants a champ tres homogene. Le calcul de tels bobinages fait appel a des methodes complexes dont l'execution pratique necessite l'emploi de machines a calculer. Le present rapport decrit un ensemble de programmes permettant de calculer, dans le cas de systemes de revolution de structure quelconque, le champ dans tout l'espace, les lignes de force du champ, les efforts electromagnetiques, les selfs et mutuelles, et de determiner des enroulements de compensation destines a uniformiser le champ. Ces programmes ont servi au calcul de deux aimants particuliers dont les caracteristiques detaillees sont fournies a titre d'application. (auteur)

  5. Radio-active pollution near natural uranium-graphite-gas reactors; La pollution radioactive aupres des piles uranium naturel - graphite - gaz

    Energy Technology Data Exchange (ETDEWEB)

    Chassany, J; Pouthier, J; Delmar, J [Commissariat a l' Energie Atomique, Chusclan (France). Centre de Production de Plutonium de Marcoule

    1967-07-01

    The results of numerous evaluations of the contamination are given: - Reactors in operation during maintenance operations. - Reactors shut-down during typical repair operations (coolants, exchangers, interior of the vessel, etc. ) - Following incidents on the cooling circuit and can-rupture. They show that, except in particular cases, it is the activation products which dominate. Furthermore, after ten years operation, the points at which contamination liable to emit strong doses accumulates are very localized and the individual protective equipment has not had to be reinforced. (authors) [French] Les resultats de nombreuses evaluations de la contamination sont donnes: - Piles en marche pendant les operations d'entretien - Piles a l'arret au cours des chantiers caracteristiques (refrigerants, echangeurs, interieur du caisson, etc.) - A la suite d'incidents sur le circuit de refroidissement et de rupture de gaine. Ils montrent que, sauf cas particulier, ce sont essentiellement les produits d'activation qui dominent. Par ailleurs apres 10 ans de fonctionnement, les points d'accumulation de la contamination susceptibles de delivrer des debits de dose importants restent tres localises et les moyens de protection individuels utilises n'ont pas du etre renforces. (auteurs)

  6. Determination of plateau slope and activity using filter measurement results and W. Chauvenet's criterion (Mage II and Fortran IV calculation programmes); Determination de pente de palier et d'activite a partir de resultats de mesure filtres selon le critere de W. Chauvenet (programmes de calcul en Mage II et Fortran IV)

    Energy Technology Data Exchange (ETDEWEB)

    Becker, A [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires, Departement d' Electronique Generale, Laboratoire de Metrologie de la Radioactivite

    1967-10-01

    In order to permit (at least partially) the objective comparison of plateau characteristics of gas-ionisation counters, plateaus which are obtained when each radioactive sample from normal LMR production is measured, a programme has been drawn up (on an electronic computer) comprising a processing section using least squares for obtaining the corrected plateaux and energies. With a view to an automatic operation of radio-measurement chains, the programme also comprises a preliminary section in which the statistical considerations of B. Peirce have been applied in the version better known as Chauvenet's criterion; this has been done with a view to eliminate measurement results which are dubious and even totally wrong. (author) [French] Pour rendre possibles (au moins partiellement) des comparaisons objectives entre paliers de caracteristiques de compteurs a ionisation gazeuse, paliers traces lors de la mesure de chaque etalon radioactif de la production courante du L.M.R., il a ete ecrit un programme (sur machine a calculer electronique) comportant une partie de traitement par les moindres carres en vue de la determination de pentes et d'activites corrigees. En prevision d'une exploitation automatique de cha es de radio-mesure, le programme comporte en outre une partie preliminaire dans laquelle des considerations statistiques dues a B. Peirce ont ete appliquees dans leur version plus connue sous le nom de critere de Chauvenet et ce dans le but d'une elimination des resultats de mesure suspects et meme veritablement aberrants. (auteur)

  7. Staff Organization in Nuclear Power Stations; Organisation du personnel des centrales nucleaires; Organizatsiya personala na atomnykh ehlektrostantsiyakh; Organizacion del personal de las centrales nucleares

    Energy Technology Data Exchange (ETDEWEB)

    Scuricini, G. B. [Comitato Nazionale Energia Nucleare, Roma (Italy)

    1963-10-15

    This paper deals with the organization of operating and maintenance staff at nuclear power stations in Italy and manpower variations, either because the plants themselves differ or are organized in some special way. Staff doing jobs for which a specific training is required are given special consideration in the paper. (author) [French] Dans le memoire, on examine l'organisation du personnel d'exploitation et d'entretien des centrales nucleaires italiennes et les differences existant dans les effectifs, differences dues soit aux caracteristiques des centrales memes, soit aux particularites d'organisation des entreprises. Le personnel charge de fonctions determinees pour lesquelles un entrainement special est requis, fait l'objet d'une attention particuliere. (author) [Spanish] En la memoria se examina la organizacion del personal de explotacion y conservacion de las centrales nucleares italianas y las diferencias que existen entre sus efectivos, diferencias que se deben a las caracteristicas de las mismas centrales o a las particularidades de organizacion de las empresas. El autor dedica especial atencion al personal encargado de funciones que requieren una formacion profesional especial. (author) [Russian] Issleduyutsya voprosy organizatsii personala, zanimayushchegosya ehkspluatatsiej ital'yanskikh atomnykh ehlektrostantsij i ukhodom za nimi, a takkhe razlichiya v sostave personala, vytekayushchie libo iz kharakternykh osobennostej samikh stantsij, libo iz osobennostej organizatsii predpriyatij. Osoboe vnimanie udelyaetsya personalu, kotoromu porucheny opredelennye funktsii, trebuyushchie spetsial'noj pod go tovki. (author)

  8. Calculation programme for transient thermo-pneumatic flows; Programme de calcul pour les ecoulements transitoires thermopneumatiques

    Energy Technology Data Exchange (ETDEWEB)

    Coste, D. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    With a view to determining the changes occurring in gas reactors after cooling accidents, a calculation programme is established for unidimensional gas flows with pressure drops, heat exchanges and in certain cases blowing, in a reticulated lattice. Any schematization can be taken into account by the use of a set of indices. This programme, of which the FORTRAN list is given, is applied to particular cases of sudden pressure drops in the circuits. The results obtained are in good agreement with those obtained both from the graphical method using the characteristics and from experimental recorded data. (author) [French] En vue de determiner les evolutions des reacteurs a gaz apres accident de refroidissement, on etablit un programme de calcul pour les ecoulements gazeux unidimensionnels avec pertes de charge, echanges thermiques et eventuellement soufflage, en reseau maille. Toute schematisation peut etre prise en compte grace a un jeu d'indices. Ce programme, dont la liste FORTRAN est presentee, est applique a des cas particuliers de degonflage brutal de circuits. Ses resultats sont en bon accord, d'une part avec ceux de la methode graphique des caracteristiques, d'autre part avec des enregistrements experimentaux. (auteur)

  9. Contribution to the study of the evaporation of aqueous uranyl nitrate solutions; Contribution a l'etude de l'evaporation des solutions aqueuses de nitrate d'uranyle

    Energy Technology Data Exchange (ETDEWEB)

    Billy, J [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1967-05-15

    This work was carried out with a view to define the conditions under which is affected the concentration of aqueous uranyl nitrate solutions one of the steps in uranium extraction metallurgy. The first port is devoted to the experimental determination of the physical characteristics of aqueous uranyl nitrate solutions, from dilute to concentrated solutions. The second part of this work is devoted to the isothermal evaporation of solution a west ted-wall column; this chemical engineering study has been more particularly devoted to the definition of the influence of the dynamics of the liquid phase on the exchange of matter between the two phases in contact. (author) [French] La concentration par evaporation des solutions aqueuses de nitrate d'uranyle constitue une etape de la metallurgie de l'uranium dont ce travail a voulu preciser la connaissance. Dans ce but, une premiere partie a ete consacree a la determination experimentale de caracteristiques physiques des solutions aqueuses de nitrate d'uranyle, des solutions diluees aux solutions saturees. Dans une deuxieme partie, ce travail a porte sur l'evaporation isotherme des solutions dans une colonne a paroi mouillee; cette etude de genie chimique a ete plus particulierement orientee de facon a preciser l'influence de la dynamique de la phase liquide sur l'echange de matiere entre les deux phases en contact. (auteur)

  10. Measurement of the electron density of a plasma by interferometry with a He - Ne laser ({lambda} = 3.39 {mu}); Mesure de la densite electronique d'un plasma par interferometrie avec un laser He - Ne ({lambda} = 3.39 {mu})

    Energy Technology Data Exchange (ETDEWEB)

    Belland, P [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1968-07-01

    The characteristics of the He-Ne gas laser used in a simple interferometric technique have been studied. After passing through the plasma, the beam is reflected back into the laser cavity, and the intensity of the laser itself, modulated by this optical feedback, is used to observe the fringes. Furthermore, owing to the coupling of the two laser transitions 0.63{mu} (red) and 3.39{mu} (infra red), interferences in the infra red can be detected by a simple photomultiplier monitoring the red line. This method has been applied to two plasma machines (E.P.P.E. and SABLIER) for spatial and temporal measurements of the mean electron density. (author) [French] Nous avons etudie les caracteristiques d'un laser a gaz He-Ne utilise dans une technique simple d'interferometrie. La lumiere qui traverse le plasma est reinjectee dans le laser, et l'intensite propre de celui-ci, modulee par cette reinjection, sert a observer les franges. De plus, a cause du couplage des deux transitions laser: 0.63{mu} (rouge) et 3.39{mu} (infrarouge), les interferences dans l'infrarouge peuvent etre detectees par un simple photomultiplicateur sensible au rouge. Nous avons applique cette methode a deux machines a plasma (E.P.P.E. et SABLIER) pour la mesure de la densite electronique moyenne en fonction du temps et de l'espace. (auteur)

  11. Calculation programme for transient thermo-pneumatic flows; Programme de calcul pour les ecoulements transitoires thermopneumatiques

    Energy Technology Data Exchange (ETDEWEB)

    Coste, D [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    With a view to determining the changes occurring in gas reactors after cooling accidents, a calculation programme is established for unidimensional gas flows with pressure drops, heat exchanges and in certain cases blowing, in a reticulated lattice. Any schematization can be taken into account by the use of a set of indices. This programme, of which the FORTRAN list is given, is applied to particular cases of sudden pressure drops in the circuits. The results obtained are in good agreement with those obtained both from the graphical method using the characteristics and from experimental recorded data. (author) [French] En vue de determiner les evolutions des reacteurs a gaz apres accident de refroidissement, on etablit un programme de calcul pour les ecoulements gazeux unidimensionnels avec pertes de charge, echanges thermiques et eventuellement soufflage, en reseau maille. Toute schematisation peut etre prise en compte grace a un jeu d'indices. Ce programme, dont la liste FORTRAN est presentee, est applique a des cas particuliers de degonflage brutal de circuits. Ses resultats sont en bon accord, d'une part avec ceux de la methode graphique des caracteristiques, d'autre part avec des enregistrements experimentaux. (auteur)

  12. D'une ouverture de la voyelle /epsilon/ en finale absolue en francais quebecois : analyse acoustique et perceptive

    Science.gov (United States)

    Riverin-Coutlee, Josiane

    Cette contribution est consacree a l'ouverture du /epsilon/ en finale absolue, un phenomene phonetique repute etre en declin en francais quebecois et caracteristique de locuteurs âges, peu scolarises, issus de milieux populaires et s'exprimant en situation de communication informelle. Une analyse acoustique de 480 voyelles /epsilon/ issues de la parole formelle de 40 jeunes etudiants universitaires originaires des centres urbains de Saguenay et de Quebec revele toutefois que le phenomene est encore bien vivant en francais quebecois et qu'il est plus frequent chez les locuteurs de Saguenay, une tendance validee auditivement par accord inter-juges. Les resultats d'un test de discrimination et d'identification mene aupres de 26 etudiants universitaires originaires de ces deux memes villes indiquent que les auditeurs naifs de Saguenay semblent moins sensibles a la variation et moins enclins a juger de l'origine geographique d'un locuteur a partir de sa prononciation de la voyelle /epsilon/ en fin de mot.

  13. {alpha} counting device with pulse ionization chamber; Ensemble de comptage {alpha} a chambre d'ionisation a impulsion

    Energy Technology Data Exchange (ETDEWEB)

    Engelman, J; Guillon, H [Commissariat a l' Energie Atomique, Saclay(France). Centre d' Etudes Nucleaires

    1953-07-01

    This device has been achieved more especially in view of the control, by measure of activity {alpha}, of chemical separations. The sought-after features were the following: - simple handling; possibility to do some measures fast and frequent. It imposed the choice of an ionization chamber at air pressure; - possibility to count {alpha} in presence of a continuous {beta} background noise, which imposed a resolution time as short as possible; - absence of micro-phonics, which imposed a study of suspension of the room; - great safety of use. (author) [French] Cet appareil a ete realise plus particulierement en vue du controle, par mesure d'activite {alpha}, de separations chimiques. Les caracteristiques recherchees etaient les suivantes: - maniement simple; possibilite d'effectuer des mesures rapides et frequentes. Cela imposait le choix d'une chambre d'ionisation a air a pression atmospherique; - possibilite de compter des {alpha} en presence d'un fond continu de {beta}, ce qui imposait un temps de resolution aussi court que possible; - absence de microphonie, ce qui demandait une etude du mode de suspension de la chambre; - grande securite de fonctionnement. (auteur)

  14. Automation on computer of the partial area method in the analysis of resonances induced by 'S' neutrons 2. with an interference term and extension of the method to the treatment of multi resonances (1963); Automatisation sur ordinateur de la methode des aires partielles dans l'analyse des resonances induites par les neutrons ''S''. 2, avec terme d'interference et extension de la methode au traitement des multiresonances (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Bianchi, G; Corge, C R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1963-07-01

    This report deals with the numerical analysis on an I.B.M. 7090 computer of transmission resonances induced by 's' wave neutrons in time of flight experiments. The analysis method used is the partial area one. In this second part the interference term is taken into account. Modifications have been made in the programs and subroutines described in the first part, to determine the resonant transmissions from experimental raw data, and the relating partial areas. Also programs and subroutines are thoroughly described, which estimate the resonance parameters. The field of the partial area method has been extended to cover the case where several resonances have to be treated simultaneously, provided they do not interfere. (authors) [French] Le pretent rapport a pour objet l'analyse numerique sur ordinateur I.B.M. 7090 des resonances dues aux neutrons ''s'' dans les experiences de transmission par temps de vol, la methode d'analyse utilisee etant la methode dea aires partielles. Dans cette deuxieme partie il a ete tenu compte du terme d'interference. On y trouvera une description des amenagements apportes aux programmes et sous-programmes decrits dans la premiere partie pour determiner les transmissions interfero-resonnantes a partir des donnees experimentales brutes et les aires partielles afferentes. Sont egalement decrits les programmes et sous-programmes necessaires au calcul des parametres caracteristiques des resonances. Le domaine d'application de la methode a ete etendu au traitement simultane de plusieurs resonances groupees n'interferant pas entre elles. (auteurs)

  15. Thermal, intermediate and fast neutron flux measurements using activation detectors; Mesure des flux de neutrons thermiques, intermediaires et rapides au moyen de detecteurs par activation

    Energy Technology Data Exchange (ETDEWEB)

    Brisbois, J; Lott, M; Manent, G [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1964-07-01

    The problem of neutron flux measurements using activation detectors is studied in the particular case of protection research. It is shown how it possible, it is possible, using a known thermal flux, to organise a coherent calibration system for all the detectors. The rapid neutron detectors are calibrated with respect to a reference detector (phosphorus) in a natural uranium converter; the intermediate neutron detectors with respect to gold in the axial channel of ZOE. This method makes it possible to minimise the errors due to the activation cross-sections. A brief description is given of the counting room of the Pile Safety Study Service, as well of the practical utilisation characteristics of the counters employed. (authors) [French] Le probleme de la mesure des flux de neutrons au moyen de detecteurs par activation est etudie dans le cas particulier des etudes de protections. On montre comment, a partir d'un flux thermique connu, on peut organiser un systeme coherent d'etalonnage de tous les detecteurs. Les detecteurs de neutrons rapides sont etalonnes par rapport a un detecteur de reference (phosphore) dans un convertisseur en uranium naturel; les detecteurs de neutrons intermediaires, par rapport a l'or dans le canal axial de ZOE, Cette methode permet de minimiser les erreurs dues aux sections efficaces d'activation. On decrit sommairement la salle de comptage du Service d'Etudes de Protections de Piles et on indique les caracteristiques d'emploi pratique des detecteurs utilises. (auteurs)

  16. Síndrome neuranêmica. Discussão de um caso com caráter familial e evolução aguda, em jovem

    Directory of Open Access Journals (Sweden)

    Horacio Martins Canelas

    1949-03-01

    Full Text Available Les auteurs étudient un cas d'anémie pernicieuse compliquée par la dégenérescence combiné subaig de la moelle. La maladie a commentée en 1946, à 1'âge de 18 ans, par faiblesse des jambes et paresthésies des mains et des pieds. Un éxamen clinique realisé en Avril 1948, pourtant, n'a pas montré l'existence de signes somatiques objectifs. Seulement quatre mois plus tard (fin de Juillet, le malade a presenté tout à fait brusquement un syndrome clinique de section transverse de la moelle, dont l'anesthésie montait jusqu'à la limite de T3. II est décedé le 3 de Septembre, par bronchopneumonia À l'autopsie on a rencontré des lésions caracteristiques de la dégenérescence combinée de la moelle. Le malade était un arrieré mental et son père souffrait aussi d'anémie pernicieuse et dégenérescence subaig de la moelle. Les auteurs étudient les aspects héredo-familiales, le début précoce et l'évolution aig de la maladie.

  17. Slug-Burst Detection in the G3 Reactor; La detection de rupture de gaine au reacteur G3; Obnaruzhenie razryva obolochki v reaktore G3; Deteccion de fallas del revestimiento en el reactor G3

    Energy Technology Data Exchange (ETDEWEB)

    Plisson, J. [Centre d' Etudes Nucleaires de Marcoule (France)

    1963-10-15

    The author explains the principles underlying slug-burst detection and describes the construction of the apparatus concerned. The main features are a) fully automatic operation, b) centralization of data in the control room and c) measurement by electrostatic collection on a turntable. (author) [French] Dans ce memoire, l'auteur expose les principes sur lesquels est fondee la detection de rupture de gaines et il decrit la realisation des installations. Les caracteristiques principales sont a) l'automatisme integral, b) la centralisation des informations dans la salle de commande et c) mesure par collection electrostatique sur plaque tournante. (author) [Spanish] El autor expone los principios en que se basa la deteccion de las fallas en los revestimientos de los elementos combustibles y describe las caracteristicas principales de la instalacion, que son: a) automatizacion integral, b) centralizacion de las informaciones en la sala de mandos, y c) medicion por recoleccion electrostatica sobre una placa giratoria. (author) [Russian] Izlagayutsya printsipy, na kotorykh osnovano obnaruzhenie razryva obolochki, opisyvaetsya konstruirovanie ustanovok. Osnovnye kharakteristiki takovy: a) integral'nyj avtomatizm, b) tsentralizatsiya informatsii v komandnom zale i c) izmerenie putem ehlektrostaticheskogo sobiraniya na povorachivayushchejsya plastinke. (author)

  18. Electronic device for measuring the polarization parameter in the {pi}{sup -}p {yields} {pi}{sup 0}n charge exchange reaction on a polarized proton target; Un appareillage electronique destine a la mesure du parametre de polarisation dans la reaction d'echange de charge {pi}{sup -}p {yields} {pi}{sup 0}n sur cible de protons polarises

    Energy Technology Data Exchange (ETDEWEB)

    Brehin, S [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-12-15

    An electronic apparatus has been constructed to measure the polarization parameter P{sub 0}(t) in {pi}{sup -}p {yields} {pi}{sup 0}n charge exchange scattering at 5.9 GeV/c and 11,2 GeV/c on polarized proton target. This device insures triggering of a heavy plate spark chamber, allowing visualisation of {gamma} rays from the {pi}{sup 0} decays when the associated neutron offers suitable characteristics in direction and energy. The neutron is detected by an array of 32 counters and his energy is measured by a time of flight method. Electronic circuits of this apparatus are described as test and calibration methods used. (author) [French] Un appareillage electronique a ete realise pour mesurer le parametre de polarisation P{sub 0}(t) dans la reaction d'echange de charge {pi}{sup -}p {yields} {pi}{sup 0}n a 5,9 GeV/c et 11,2 GeV/c sur une cible de protons polarises. Ce dispositif assure le declenchement d'une chambre a etincelles a plaques lourdes, permettant de visualiser les {gamma} de desitegration du {pi}{sup 0}, lorsque le neutron associe presente les caracteristiques convenables en direction et en energie. Le neutron est detecte par un ensemble de 32 compteurs et son energie est mesuree par une methode de temps de vol. Les circuits composant cet appareillage sont decrits ainsi que les methodes d'etalonnage et de verification utilisees. (auteur)

  19. Scintillation {gamma} spectrography. Physical principles. Apparatus. Operation; Spectrographie {gamma} a scintillations. Principes physiques. Appareillage. Utilisation

    Energy Technology Data Exchange (ETDEWEB)

    Julliot, C [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    The scintillation detector forms the main part of the instrument used, the electronic unit presenting the results produced. After a brief description of the process of {gamma} photon absorption in the material, the particular case of NaI (T1), the scintillator used, is examined. The intensity of the scintillation caused by {gamma} ray absorption and the characteristics of the photomultiplier play a determining part in the energy resolution of the instrument. For the {gamma} recording spectrograph, we show to what extent the technique for using the electronic unit can modify the results. A detailed description is given of the activity measurement of a {gamma}-emitting radioelement by the spectrographic method. (author) [French] Dans l'appareillage utilise, le detecteur a scintillations constitue la piece maitresse, l'ensemble electronique presente les resultats issus du detecteur. Apres avoir brievement decrit le processus d'absorption des photons {gamma} dans la matiere, nous examinons le cas particulier du NaI(T1), le scintillateur utilise. L'intensite de la scintillation provoque par l'absorption des rayons {gamma} et les caracteristiques du photomultiplicateur jouent un role determinant dans la resolution en energie de l'appareil. Pour le spectrographe {gamma} enregistreur, nous indiquons dans quelle mesure la technique d'utilisation de l'ensemble electronique peut modifier les resultats. La-mesure de l'activite d'un radioelement emetteur {gamma} par spectrographie fait l'objet d'une description detaillee. (auteur)

  20. Radio-vulcanization of natural rubber in the latex phase. Study of an experimental 1 tonne per hour production; Radio-vulcanisation du caoutchouc naturel en phase latex. Etude d'une production experimentale de 1 tonne par heure

    Energy Technology Data Exchange (ETDEWEB)

    Leveque, P; Puig, J R; Roudeix, H [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1968-07-01

    After briefly reviewing the main research carried out on the radio-vulcanization of latex and elastomers, a description is given of 4 types of cell which have been used successively with a view to industrial irradiation. They have made it possible to acquire the information necessary for resolving the main problem arising during irradiation - the formation of coagulum. The first two cell are designed for irradiation by a horizontal beam ('Dynamitron'), the two others use a vertical beam ('Circe'). The study of the properties of the rubber obtained shows it to compare favorably with 'Revultex'. In the appendix are given some characteristics of natural latex and information about its processing. (authors) [French] Apres un rappel des principales etudes sur la radio-vulcanisation du latex et des elastomeres, on decrit les quatre types de cellules successivement essayes en vue de l'irradiation industrielle. Ils ont permis d'acquerir les informations necessaires a la resolution du probleme principal pose par l'irradiation, la formation de coagulum au cours de celle,-ci. Les deux premiers sont concus pour l'irradiation par un faisceau horizontal ('Dynamitron'), les derniers par un faisceau vertical ('Circe'). L'etude des proprietes du caoutchouc obtenu montre qu'il se compare favorablement au 'Revultex'. Un apercu est donne en annexe des caracteristiques du latex naturel et de sa mise en oeuvre. (auteurs)

  1. Study of the K-bar{pi} system in the 3 bodies final states, produced by 3 GeV/c K{sup -}p interactions; Etude du systeme K-bar{pi} dans les etats finals a 3 corps, produits par les interactions K{sup -}p a 3 GeV/c

    Energy Technology Data Exchange (ETDEWEB)

    Verglas, A. [Commissariat a l' Energie Atomique, Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France)

    1966-07-01

    The K{sup -}p {yields} K{sup *} (891) {pi} reaction is a good example of a quasi two-body phenomenon, exhibiting the characteristics of 'peripherism'. The predictions of the 'one meson exchange', and 'absorption' models are compared with the experimental results. Conclusions are drawn concerning the production mechanism of the Kp {yields} K{sup *} {pi} reaction, as well as on the validity of the models. Finally, the K{sup *} (1400) resonance is studied and its isospin determined. (author) [French] La reaction K{sup p} {yields} K{sup *} (891) {pi} est un bon exemple de phenomene 'quasi deux corps' presentant les caracteristiques du 'peripherisme'. Les predictions des modeles theoriques d'un meson echange et de l'absorption sont compares aux resultats experimentaux; des conclusions sont tirees, tant sur le mecanisme de production de la reaction Kp {yields} K{sup *} {pi} que sur la validite des modeles. Enfin, la resonance K{sup *} (1400) est etudiee et son isospin determine. (auteur)

  2. Calculation of the shock-wave in the region close to an underground nuclear explosion (method Cades); Calcul de l'onde de choc en zone proche d'une explosion nucleaire souterraine (methode cades)

    Energy Technology Data Exchange (ETDEWEB)

    Supiot, F; Brugies, J [Commissariat a l' Energie Atomique, Bruyeres-le-Chatel (France). Centre d' Etudes

    1969-07-01

    The outline of a method is presented for calculating the characteristics of a shock wave produced by an underground nuclear explosion (pressure, wave velocity, velocity of the medium, energy left in the medium by the shock, etc.). By means of an application to a granitic medium and of a comparison with results obtained during French nuclear explosions, it has been possible to show the good agreement existing between the calculations and the experimental results. The advantages of such a method for studying the industrial applications of underground nuclear explosions are stressed. (authors) [French] On expose les grandes lignes d'une methode de calcul des caracteristiques de l'onde de choc issue d'une explosion nucleaire souterraine (pression, vitesse de l'onde, vitesse du milieu, energie deposee par le choc dans le milieu...). Une application a un milieu granitique et une comparaison aux resultats obtenus au cours d'explosions nucleaires francaises permet de montrer la bonne concordance entre le calcul et les resultats experimentaux. On souligne l'interet d'une telle, methode pour l'etude d'applications industrielles des explosions nucleaires souterraines. (auteurs)

  3. Rapid method of identification of {beta}-ray emitters and of {beta}-radioactive impurity dosage (1961); Methode rapide d'identification des emetteurs-{beta} et de dosage d'impuretes radioactives-{beta} (1961)

    Energy Technology Data Exchange (ETDEWEB)

    Le Gallic, Y; Legrand, J; Grinberg, B [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-07-01

    We describe a simple method of radioactive analysis, which allows an accurate determination of maximal energies of {beta}-emitters, and detection and titration of radioactive impurities in radionuclides as well. The method described, which uses a plastic scintillator, is based on the fact that the curve obtained by plotting the number of pulses measured against the threshold is a straight line, in the case of pure {beta}-emitters. We then derive a simple relation between the data of this straight line and the maximal energy of the {beta}-spectrum of the radionuclide under consideration. (authors) [French] Description d'une methode simple d'analyse radioactive, permettant de determiner avec precision l'energie maximum des emetteurs-{beta}, ainsi que de deceler et de doser les impuretes radioactives dans un radionuclide. La technique decrite utilise un scintillateur plastique. On exploite le fait que la courbe du nombre d'impulsions mesurees, en fonction du seuil de discrimination, est une droite, pour un emetteur-{beta} pur. Une relation simple entre les caracteristiques de cette droite et l'energie maximum du spectre-{beta} du radionuclide, correspondant, a ete etablie. (auteurs)

  4. A crystallographic and spectroscopic study of crystal sites in the 'spinel' structure; Etude cristallographique et spectroscopique des sites cristallins dans la structure 'spinelle'

    Energy Technology Data Exchange (ETDEWEB)

    Drifford, M. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-06-15

    A crystallographic study on magnesium aluminates led to the determination of crystal site average distortion. A spectroscopic study of transition elements doped spinels gave the position of the doping element in tetrahedral (A) or octahedral (B) sites, and the local distortion of the latter. The comparison of average and local parameters points to differences in the behaviour of doping elements and shows the size of (A) sites are independent of the host crystal composition while the average size of (B) sites varies with the composition. (author) [French] Une etude cristallographique des aluminates de magnesium a permis de determiner la deformation moyenne des sites cristallins. Une etude spectroscopique des aluminates de magnesium dopes avec des elements de transition a permis de localiser les dopants entre les sites tetraedriques (A) et octaedriques (B) et d'etudier la deformation locale de ces sites. La comparaison entre les parametres moyens et locaux a caracterise le comportement du dopant et montre que les dimensions des sites (A) sont independantes de la composition de la matrice, alors que les caracteristiques geometriques moyennes des sites (B) varient continument avec la composition. (auteur)

  5. Underground nuclear explosions. Geological survey of the cavities; Explosions nucleaires souterraines etude geologique des cavites

    Energy Technology Data Exchange (ETDEWEB)

    Faure, J [Commissariat a l' Energie Atomique, Bruyeres-le-Chatel (France). Centre d' Etudes

    1969-07-01

    A geological survey of underground nuclear explosions makes it possible to determine the main characteristics of the cavity formed. The lower portion is spherical; the same was very likely true of the roof, which collapses in the majority of media with the exception of rock-salt. Its radius, for a given bomb size, can vary by a factor of two according to the type of rock. The lay-out of its contents depends on the characteristics of the solid and liquid products at the moment of the roof collapse; according to the medium involved, mixing of the rubble and the mud-flow occurs (granite) or does not occur (tuff and alluvia). In all media, the average physical properties can be evaluated. (author) [French] L'etude geologique d'explosions nucleaires souterraines permet de determiner les principaux caracteres de la cavite creee. Sa partie inferieure est spherique; il en etait vraisemblablement de meme de sa voute, effondree dans la plupart des milieux a l'exception du sel gemme. Son rayon, a energie d'engin egale, varie selon les roches du simple au double. La disposition de son contenu depend des caracteristiques des produits solides et liquides au moment de la chute du toit; selon le cas, il n'y a pas (tuf et alluvions) ou il y a (granite) melange des eboulis et des laves. Dans tous les milieux, les proprietes physiques moyennes peuvent etre evaluees. (auteur)

  6. Contribution to the Study of Nuclear Magnetic Resonance in Ferromagnets; Contribution a l'etude de la resonance nucleaire dans les corps ferromagnetiques

    Energy Technology Data Exchange (ETDEWEB)

    Robert, C. [Commissariat a l' Energie Atomique, Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France)

    1962-07-01

    Properties of nuclear magnetic resonance in the field acting on the nucleus in a ferromagnet were studied. Nuclei were {sup 57}Fe in iron and yttrium iron garnet. Static properties of resonance (frequency, line-width, dipolar structure) were investigated and compared with magnetic behavior and magnetic structure of the materials. Relaxation in garnet points out importance of long range fluctuations induced by impurities in a ferromagnetic lattice. (author) [French] Nous avons etudie les proprietes de la resonance nucleaire dans le champ existant a remplacement d'un noyau dans un corps ferromagnetique (champ local). Les noyaux etaient ceux de {sup 57}Fe dans le fer et dans le grenat d'yttrium et de fer. Les proprietes statiques de la resonance (frequence de resonance, largeur de la raie, structures dues a l'interaction dipolaire) ont ete etudiees et reliees aux caracteristiques magnetiques et a la structure de ces corps. La relaxation dans le grenat a mis en evidence les fluctuations a longue distance induites par des impuretes dans un reseau ferromagnetique. (auteur)

  7. Construction of a flash-photolysis apparatus having a short discharge time; Realisation d'un appareil de photolyse-eclair a faible duree de decharge

    Energy Technology Data Exchange (ETDEWEB)

    Devillers, C. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    Flash photolysis aims at reaching directly the primary mechanisms resulting from the action of light on an absorbent matter. This makes it necessary to produce a flash as short and as bright as possible. Our main effort was directed towards reducing the duration of the flash by decreasing the self-inductance of the discharge circuit. A description of this circuit and study of the characteristics of the apparatus are followed by a short description of the two analytical methods: flash spectrography and absorption spectrophotometry at a given wave-length. (author) [French] La photolyse-eclair cherche a atteindre directement les mecanismes primaires resultant de l'action de la lumiere sur une matiere absorbante. Ceci amene a produire un eclair aussi bref et intense que possible. Notre effort s'est porte sur la reduction de duree de l'eclair par diminution de la self-induction du circuit de decharge. Une description de ce circuit et une etude des caracteristiques de l'appareil precedent une breve description des deux methodes d'analyse; spectrographie eclair et spectrophotometrie d'absorption a longueur d'onde choisie. (auteur)

  8. Contribution to the Study of Nuclear Magnetic Resonance in Ferromagnets; Contribution a l'etude de la resonance nucleaire dans les corps ferromagnetiques

    Energy Technology Data Exchange (ETDEWEB)

    Robert, C [Commissariat a l' Energie Atomique, Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France)

    1962-07-01

    Properties of nuclear magnetic resonance in the field acting on the nucleus in a ferromagnet were studied. Nuclei were {sup 57}Fe in iron and yttrium iron garnet. Static properties of resonance (frequency, line-width, dipolar structure) were investigated and compared with magnetic behavior and magnetic structure of the materials. Relaxation in garnet points out importance of long range fluctuations induced by impurities in a ferromagnetic lattice. (author) [French] Nous avons etudie les proprietes de la resonance nucleaire dans le champ existant a remplacement d'un noyau dans un corps ferromagnetique (champ local). Les noyaux etaient ceux de {sup 57}Fe dans le fer et dans le grenat d'yttrium et de fer. Les proprietes statiques de la resonance (frequence de resonance, largeur de la raie, structures dues a l'interaction dipolaire) ont ete etudiees et reliees aux caracteristiques magnetiques et a la structure de ces corps. La relaxation dans le grenat a mis en evidence les fluctuations a longue distance induites par des impuretes dans un reseau ferromagnetique. (auteur)

  9. Extraction and purification of plutonium by a tertiary amine; Extraction et purification du plutonium par une amine tertiaire

    Energy Technology Data Exchange (ETDEWEB)

    Trentinian, M de; Chesne, A [Commissariat a l' Energie Atomique, Fontenay aux Roses, Section de Chimie des Actimides (France).Centre d' Etudes Nucleaires; Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    Trilaurylamine diluted with a paraffinic solvent (dodecane) was studied as part of the research dealing with the separation and purification of plutonium. The physical properties (solubility of nitrates in the amine as a function of temperature) and the resistance to radiations of this substance were examined. The extraction characteristics of nitric solutions of plutonium, uranium and certain fission products are given as a function of the following factors: concentration of the various ions in solution, valency states. A method of plutonium purification based on these results is presented. (author) [French] La trilaurylamine diluee par un solvant paraffinique (dodecane) a ete etudiee dans le cadre des recherches concernant la separation et la purification du plutonium. Une etude des caracteres physiques (solubilite des nitrates dans l'amine en fonction de la temperature) s'ajoute a celle de la tenue aux radiations de ce corps. Les caracteristiques d'extraction de solutions nitriques de plutonium, uranium, et certains produits de fission, sont donnes en fonction des facteurs suivants: concentration des differents ions en solution, etats de valence. On presente une methode de purification du plutonium basee sur ces resultats. (auteur)

  10. Histological data concerning the pig (sus scrofa) for use in radiobiology. I. Normal histology of certain systems. 2. Injuries caused by total {gamma} irradiation; Donnees histologiques sur le porc (sus scrofa), utilisables en radiobiologie. 1. histologie normale de certains appareils. 2. etude des lesions consecutives a une irradiation {gamma} totale

    Energy Technology Data Exchange (ETDEWEB)

    Guenet, J.L.; Vaiman, M.; Nizza, P. [Commissariat a L' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1966-06-01

    The domestic pig lately become a laboratory whose anatomical and physiological characteristics appear to be appreciated for certain radiological studies. In this report the authors describe research which they have carried out (in particular in the field of histology) on domestic pigs of different species with a view to compiling a record which might be of help to future workers in this field. The second part of their work deals with anatomical and histological injuries caused by total exposure to gamma radiation from cobalt 60 at doses of around 285 rads. (authors) [French] Le porc domestique est devenu depuis peu un animal de laboratoire, dont les caracteristiques anatomiques et physiologiques paraissent fort appreciees pour certaines etudes de radiobiologie. Dans ce rapport les auteurs font part des recherches qu'ils ont effectuees (notamment dans le domaine de l'histologie) sur des porcs domestiques de differentes races, de maniere a constituer un document capable de venir en aide aux utilisateurs eventuels. La deuxieme partie de leur travail traite de lesions anatomiques et histologiques, consecutives a des expositions totales aux rayonnements gamma du cobalt 60 a des doses voisines de 285 rads. (auteurs)

  11. Anisotropies of the neutron emission of the 'Focus' discharge compared with different theoretical models; Anisotropies de l'emission neutronique de la decharge 'Focus' comparees a divers modeles theoriques

    Energy Technology Data Exchange (ETDEWEB)

    Patou, Claude; Simonnet, Alain

    1969-08-06

    When a plasma emits enough neutrons to make an analysis of this neutrons possible, the study of emission characteristics allows the mechanism governing fusion reaction to be specified. The experimental study of neutron flow and energy anisotropies is herein compared with various possible theoretical models. It seems that the 'Boiler' model (thermal plasma in movement) matches the obtained results. Only observed flow values in the discharge axis remain unexplained. Although the study approach does not allow to be sure of plasma thermalization in the strict meaning of the term, it seems that there is a relatively well established anisotropy of the speed distribution function of reacting ions [French] Lorsqu'un plasma emet suffisamment de neutrons pour les soumettre a l'analyse, l'etude des caracteristiques de l'emission permet de preciser le mecanisme responsable des reactions de fusion. L'etude experimentale des anisotropies du flux et de l'energie des neutrons est comparee a divers modeles theoriques possibles. Il semble que le modele du 'Boiler' - plasma thermique en mouvement - s'accorde avec nos resultats. Seules les valeurs des flux observes selon l'axe de la decharge restent sans explication. Bien que ce moyen d'etude ne permette pas d'etre certain de la thermalisation du plasma au sens strict du terme, il semble cependant qu'on se trouve en presence d'une isotropie relativement bien realisee de la fonction de distribution des vitesses des ions qui entrent en reaction. (auteurs)

  12. Statistical methods for anomaly detection in the complex process; Methodes statistiques de detection d'anomalies de fonctionnement dans les processus complexes

    Energy Technology Data Exchange (ETDEWEB)

    Al Mouhamed, Mayez

    1977-09-15

    In a number of complex physical systems the accessible signals are often characterized by random fluctuations about a mean value. The fluctuations (signature) often transmit information about the state of the system that the mean value cannot predict. This study is undertaken to elaborate statistical methods of anomaly detection on the basis of signature analysis of the noise inherent in the process. The algorithm presented first learns the characteristics of normal operation of a complex process. Then it detects small deviations from the normal behavior. The algorithm can be implemented in a medium-sized computer for on line application. (author) [French] Dans de nombreux systemes physiques complexes les grandeurs accessibles a l'homme sont souvent caracterisees par des fluctuations aleatoires autour d'une valeur moyenne. Les fluctuations (signatures) transmettent souvent des informations sur l'etat du systeme que la valeur moyenne ne peut predire. Cette etude est entreprise pour elaborer des methodes statistiques de detection d'anomalies de fonctionnement sur la base de l'analyse des signatures contenues dans les signaux de bruit provenant du processus. L'algorithme presente est capable de: 1/ Apprendre les caracteristiques des operations normales dans un processus complexe. 2/ Detecter des petites deviations par rapport a la conduite normale du processus. L'algorithme peut etre implante sur un calculateur de taille moyenne pour les applications en ligne. (auteur)

  13. 4{pi} proportional counter for absolute measurement of {beta}-emitters; Compteur 4{pi} proportionnel destine a la mesure absolue d'emetteurs {beta}

    Energy Technology Data Exchange (ETDEWEB)

    Perolat, J P; Laine, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-07-01

    The 4{pi} counter is commonly used to measure the activity of {beta} sources, the one we describe does not advance a new conception but the issue of several years of investigations. The apparatus presents good performances about the qualities commonly required in that kind of counter: detection efficiency, plateau and dead time. Moreover technical characteristics give a great flexibility in use, particularly a possibility of adaptation in a {beta},{gamma} coincidence unit. (authors) [French] Le compteur 4{pi} proportionnel est couramment, utilise pour mesurer l'activite de sources {beta}, celui que nous decrivons ne represente pas une conception nouvelle, mais plutot l'aboutissement de plusieurs annees d'etudes. Cette installation presente des performances satisfaisantes en ce qui concerne les qualites habituellement requises dans ce type de compteur: l'efficacite de detection, le palier et le temps mort. En outre, certaines caracteristiques techniques qui lui sont propres lui conferent une grande souplesse d'utilisation, en particulier la possibilite d'adaptation a un ensemble de mesures par coincidences 4{pi} {beta} {gamma}. (auteurs)

  14. Contribution to the study of excited levels of {sup 7}Be obtained from the reaction {sup 6}Li (p, {alpha}); Contribution a l'etude des niveaux excites du {sup 7}Be obtenus par la reaction {sup 6}Li (p, {alpha})

    Energy Technology Data Exchange (ETDEWEB)

    Beaumevieille, H. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1964-05-01

    The interpretation of the results of the reaction {sup 6}Li (p, {alpha}) in the energy range 100 keV to 3 MeV has been done with the next levels of {sup 7}Be : 3/2- (5,9 MeV), 3/2+ (6,2 MeV), 5/2- (7,18 MeV) and a level the characteristics of which may be 1/2+ or {sup 4}P (9,5 MeV). (author) [French] L'interpretation des resultats de la reaction {sup 6}Li (p, {alpha}) dans la gamme d'energie 100 keV a 3 MeV a ete faite avec les niveaux suivants du {sup 7}Be : 3/2- (5,9 MeV), 3/2 + (6,2 MeV), 5/2- (7,18 MeV) et un niveau dont les caracteristiques doivent etre 1/2+ ou {sup 4}P (9,5 MeV). (auteur)

  15. Spectrum stabilizer; Stabilisateur de spectres

    Energy Technology Data Exchange (ETDEWEB)

    Detourne, G. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires, Departement d' electronique generale, Service d' instrumentation nucleaire

    1967-05-01

    A spectrum stabilizer is a control mechanism which renders an analytical chain reliable. It can detect a drift in the amplification and in the base of the energy scale, and can modify the characteristics of this chain. The results of a theoretical study make it possible to calculate the width and the abscissae of the peaks of a stabilized spectrum as a function of the drifts. The SPECTROSTAB is a numerical stabilizer of a continuous type; it provides the artificial reference peak at low energies. Experimental results give the performances obtained on a reference peak provided by a semi-conductor detector, in the field of gamma spectroscopy. (author) [French] Un stabilisateur de spectres est un asservissement qui permet de rendre fidele une cha e d'analyse. Il detecte les derives du gain et de l'origine de l'echelle des energies et reagit sur les caracteristiques de cette cha e. Les resultats d'une etude theorique permettent le calcul des elargissements et des abscisses des pics d'un spectre stabilise, en fonction des derives. Le SPECTROSTAB est un stabilisateur numerique du genre continu; il fournit le pic de reference artificiel aux basses energies. Des resultats experimentaux donnent les performances obtenues sur un pic de reference fourni par un detecteur a semi-conducteur, dans le domaine de la spectrometrie gamma. (auteur)

  16. Automation on computers of the partial area method for the analysis of 's' neutron induced resonances. I. Without interference terms. (1962); Automatisation sur ordinateur de la methode des aires partielle dans l'analyse des resonances induites par les neutrons 's'. I. sans terme d'interference. (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Bianchi, G; Corge, C R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1962-07-01

    This report deals with numerical analysis of transmission resonances induced by 's' wave neutrons in time of flight experiments. The analysis method used is the partial area one. The only case treated here, in this first part, is the one when the interference term can be neglected. Programs and subroutines are thoroughly described, which determine from experimental raw data the resonant transmission, the partial areas, and the resonance parameters. (authors) [French] Le present rapport a pour objet l'analyse numerique sur ordinateur IBM 7090, des resonances dues aux neutrons 's' dans les experiences de transmission par temps de vol, la methode d'analyse utilisee etant la methode des aires partielles. Dans cette premiere partie, seul a ete envisage le cas ou le terme d'interference peut etre neglige. On y trouvera une description detaillee des programmes et sous programmes elabores pour determiner les transmissions resonantes avec leur trace, a partir des donnees experimentales brutes, les aires partielles afferentes ainsi que les parametres caracteristiques des resonances. (auteurs)

  17. The noise-time of response compromise in d.c. period meters. A new type of circuit (1961); Le compromis bruit-temps de reponse dans les periodemetres a courant continu. un nouveau type de circuit (1961)

    Energy Technology Data Exchange (ETDEWEB)

    Friedling, G [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-07-01

    The report compares the characteristics of three period meter circuits: - a linear circuit - a circuit which is non-linear according to the nuclear reactor period - a circuit which is non-linear according to the period and the power of the reactor. This last type of reactor has a fast time of response if the power is high or if the period is short, and it has a slow time of response when the power is low and the period long; this system makes it possible to maintain the noise at an acceptable level under all normal working conditions of the reactor. (author) [French] Le rapport compare les caracteristiques de trois circuits de periodemetres: - un circuit lineaire; - un circuit non lineaire selon la periode du reacteur nucleaire; - un circuit non lineaire selon la periode et la puissance du reacteur. Ce dernier type de circuit a un court temps de reponse si la puissance est faible et la periode grande; ce systeme permet de limiter le bruit a des niveaux acceptables dans toutes les conditions normales de fonctionnement du reacteur. (auteur)

  18. Production and study of mixed Al-Al{sub 2}O{sub 3} thin films for passive electronic circuits; Realisation et etude des couches minces mixtes Al-Al{sub 2}O{sub 3} pour circuits electroniques passifs

    Energy Technology Data Exchange (ETDEWEB)

    Pruniaux, B [Commissariat a l' Energie Atomique, 38 - Grenoble (France). Centre d' Etudes Nucleaires

    1967-07-01

    A new vacuum deposition process, named reactive evaporation, is used to realize passive thin film circuits. Using aluminium, oxidized at various steps in its vapor phase, we obtain: - Al-Al{sub 2}O{sub 3} cermet resistors (R{sub {open_square}} = 10000 {omega}{sub {open_square}}, CTR <{+-} 150 ppm/deg. C) which show oscillations of the resistivity versus the thickness of the layer, in distinction to classical theory. - Al{sub 2}O{sub 3} capacitors (C{sub {open_square}} = 60000 pf/cm{sup 2}, tg {delta} < 0.5 per cent). These thin film components present good electrical behaviour and should find interesting applications in integrated circuits. (author) [French] Une nouvelle technique de depot sous vide, l'evaporation reactive est utilisee pour realiser des circuits passifs en couches minces. En oxydant, en phase vapeur, de l'aluminium a differents degres, on obtient: - des resistances en cermet Al-Al{sub 2}O{sub 3} (R{sub {open_square}} = 10000 {omega}{sub {open_square}}, CTR <{+-} 150 ppm) dont Ia resistivite oscille en fonction de l'epaisseur, contrairement aux previsions de la theorie classique. - Des capacites en Al{sub 2}O{sub 3} (C{sub {open_square}} = 60000 pf/cm{sup 2}, tg {delta} < 0.5 pour cent). Ces elements presentent de bonnes caracteristiques electriques et seraient avantageusement utilises en circuits integres. (auteur)

  19. Introduction to the study of an optimal control for irradiation loops of the reactor Pegase; Introduction a l'etude d'une commande optimale des boucles d'irradiation du reacteur Pegase

    Energy Technology Data Exchange (ETDEWEB)

    Guintrand, C [Commissariat a l' Energie Atomique, Cadarache (France). Centre d' Etudes Nucleaires

    1968-07-01

    The control system under consideration is made up of: a regulation unit consisting of a conventional nonlinear looped circuit for static tests, a cycling unit operating in open loop for dynamic tests. After a definition of a mathematical model for an irradiation loop, the behaviour of the regulation unit is studied, first of all theoretically using three-dimensional topological methods, and then by analogue simulation. A prototype unit is under construction and its principal characteristics are given. Finally, as far as the cycling unit is concerned, the first tests involving self-instruction technique, are described. (author) [French] Le systeme de commande envisage se compose de r: une unite de regulation se presentant sous la forme d'un circuit boucle classique non-lineaire, pour les essais statiques, une unite de cyclage fonctionnant en boucle ouverte, pour les essais dynamiques. Apres avoir defini un modele mathematique d'une boucle d'irradiation, on etudie le comportement de l'unite de regulation d'abord de facon theorique par les methodes topologiques a trois dimensions, puis par une simulation analogique. Une unite prototype est en cours de realisation, les principales caracteristiques en sont donnees. Enfin, en ce qui concerne l'unite de cyclage, les premiers essais effectues faisant appel aux techniques d'autoapprentissage, sont decrits. (auteur)

  20. The Nord-Limousin uraniferous province. Its three main deposits; La province uranifere du Nord-Limousin. Ses trois principaux gisements

    Energy Technology Data Exchange (ETDEWEB)

    Sarcia, J.A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1958-07-01

    Les Sagnes, Margnac and Les Brugeauds are the three main known deposits in the Nord-Limousin region, a rich uraniferous area; already being mined, they have only been partially explored so far, and one can safely hope for further extensions: in fact, some of these hopes have come true already. Each of these three deposits correspond to a type frequently to be found in the region, and the three of them together represent the characteristics of the Nord-Limousin uraniferous region: that is why they were selected. (author) [French] Les trois gisements decrits ici, les Sagnes, Margnac, les Brugeauds, sont les principaux actuellement connus dans la region du Nord-Limousin, si riche en gites uraniferes; deja en exploitation, ils ne sont encore que partiellement explores, et tous les espoirs d'extension laterale sont permis: certains sont deja en voie de realisation. Chacun d'eux correspond a un type frequent dans la region, et ils illustrent a eux trois les caracteristiques de la province uranifere du Nord-Limousin: c'est la raison de leur choix. (auteur)

  1. Phase-shift analysis of pion-nucleon elastic scattering below 1.6 GeV; Analyse en ondes partielles de la diffusion elastique meson {pi} - nucleon au-dessous de 1.6 GeV

    Energy Technology Data Exchange (ETDEWEB)

    Bareyre, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1968-06-01

    Experimental results of pion-nucleon elastic scattering below 1.6 GeV (total cross sections, angular distributions of elastic scattering and recoil nucleon polarizations) have been described by a partial wave analysis. This analysis has been developed, one energy at a time, with a method of least squares fits. A single solution is extracted by continuity with energy of the different solutions. Resonating behaviour has been clearly established for several partial waves. In addition to these important effects some phase shifts show rapid variations with energy. Present experimental situation does not permit to say whether these variations are due to experimental biases or to physical effects. (author) [French] Les resultats experimentaux de la diffusion elastique meson {pi} - nucleon au-dessous de 1.6 GeV (sections efficaces totales, distributions angulaires de diffusion elastique et de polarisation du nucleon de recul) sont decrits a l'aide d'une analyse en ondes partielles. Cette analyse est developpee energie par energie au moyen d'une methode d'ajustement en moindres carres. Un critere empirique de continuite des solutions en fonction de l'energie a permis d'isoler une solution unique. Des resonances sont clairement etablies pour plusieurs ondes partielles, ainsi que certains petits effets moins caracteristiques. Pour ceux-ci, la situation experimentale presente ne permet pas d'affirmer s'ils sont dus a des effets physiques ou a des biais experimentaux. (auteur)

  2. Activation analysis using {gamma} photons; Analyse par activation aux photons {gamma}

    Energy Technology Data Exchange (ETDEWEB)

    Engelmann, Ch [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-07-01

    This report summarizes all the data required for using photonuclear reactions in the field of analysis. After a brief review of the elementary properties of nuclear reactions induced by photon irradiation, the main characteristics are given of high energy (E > 20 MeV) Bremsstrahlung sources. The principle of activation analysis based on the use of photons is given. Actual examples of the analytic possibilities are described in detail, in particular in the case of the determination of very small quantities (< 10{sup -6}) of C, N, O and F. The influence of interfering nuclear reactions is discussed. (author) [French] Ce rapport se propose de resumer l'ensemble des connaissances indispensables pour l'utilisation des reactions photonucleaires a des fins analytiques. Apres quelques rappels concernant les proprietes elementaires des reactions nucleaires induites par irradiation dans les photons, les principales caracteristiques des sources de rayonnement de freinage de haute energie (E > 20 MeV)| sont donnees. Le principe de l'analyse par activation aux photons est rappele. Des exemples concrets sur les possibilites analytiques sont developpes, particulierement en ce qui concerne la determination de quantites tres faibles (< 10{sup -6}) de C, N, O et F. L'influence des reactions nucleaires parasites est discutee. (auteur)

  3. Study of the K-bar{pi} system in the 3 bodies final states, produced by 3 GeV/c K{sup -}p interactions; Etude du systeme K-bar{pi} dans les etats finals a 3 corps, produits par les interactions K{sup -}p a 3 GeV/c

    Energy Technology Data Exchange (ETDEWEB)

    Verglas, A [Commissariat a l' Energie Atomique, Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France)

    1966-07-01

    The K{sup -}p {yields} K{sup *} (891) {pi} reaction is a good example of a quasi two-body phenomenon, exhibiting the characteristics of 'peripherism'. The predictions of the 'one meson exchange', and 'absorption' models are compared with the experimental results. Conclusions are drawn concerning the production mechanism of the Kp {yields} K{sup *} {pi} reaction, as well as on the validity of the models. Finally, the K{sup *} (1400) resonance is studied and its isospin determined. (author) [French] La reaction K{sup p} {yields} K{sup *} (891) {pi} est un bon exemple de phenomene 'quasi deux corps' presentant les caracteristiques du 'peripherisme'. Les predictions des modeles theoriques d'un meson echange et de l'absorption sont compares aux resultats experimentaux; des conclusions sont tirees, tant sur le mecanisme de production de la reaction Kp {yields} K{sup *} {pi} que sur la validite des modeles. Enfin, la resonance K{sup *} (1400) est etudiee et son isospin determine. (auteur)

  4. Histological data concerning the pig (sus scrofa) for use in radiobiology. I. Normal histology of certain systems. 2. Injuries caused by total {gamma} irradiation; Donnees histologiques sur le porc (sus scrofa), utilisables en radiobiologie. 1. histologie normale de certains appareils. 2. etude des lesions consecutives a une irradiation {gamma} totale

    Energy Technology Data Exchange (ETDEWEB)

    Guenet, J L; Vaiman, M; Nizza, P [Commissariat a L' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1966-06-01

    The domestic pig lately become a laboratory whose anatomical and physiological characteristics appear to be appreciated for certain radiological studies. In this report the authors describe research which they have carried out (in particular in the field of histology) on domestic pigs of different species with a view to compiling a record which might be of help to future workers in this field. The second part of their work deals with anatomical and histological injuries caused by total exposure to gamma radiation from cobalt 60 at doses of around 285 rads. (authors) [French] Le porc domestique est devenu depuis peu un animal de laboratoire, dont les caracteristiques anatomiques et physiologiques paraissent fort appreciees pour certaines etudes de radiobiologie. Dans ce rapport les auteurs font part des recherc