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2006-04-15
This order fixes the return rate on the investments capital of electric power production in non connected areas, used for the calculation of the compensation expenses of the electric utilities. (A.L.B.)
2000-01-01
The recycling rate of plutonium and uranium are: from the whole of the plutonium separated from the spent fuel ( inferior to 1% of the nuclear matter content) attributed to France is under 50% (under 42 tons on 84 tons). From the whole of plutonium produced in the French reactors is less than 20% (42 tons on 224 tons). From the whole of the uranium separated from spent fuels attributed to France is about 10 % (1600 tons on 16000 tons). From the whole of the uranium contained in the spent fuel is slightly over 5%. (N.C.)
Measurement of effective renal plasma flow (ERPF) with {sup 123}I-orthoiodohippurate (I-123-OIH)
1996-05-01
We evaluated the necessity of attenuation correction for calculating effective renal plasma flow (ERPF) using I-123-orthoiodohippurate (OIH), an agent introduced recently to replace I-131-OIH. From a kidney phantom experiment, the attenuation coefficient ({mu}) for I-123-OIH in the human body was determined as 0.1262 cm{sup -1}. I-123-OIH renal scintigraphy was performed in 23 patients with urinary diseases with blood sampling for calculation of ERPF by Tauxe`s method. Calculated renal uptake, with or without attenuation correction, was compared with ERPF determined by Tauxe`s method. There was good correlation between renal uptake without attenuation correction and ERPF obtained by Tauxe`s method (r=0.737), while much better correlation was found between attenuation-corrected renal uptake and ERPF calculated by Tauxe`s method (r=0.816). In conclusion, attenuation correction for renal uptake is an important technique for estimating ERPF using I-123-OIH renal scintigraphy. (author)
1962-07-01
A theoretical study has been made of a fully developed turbulent flow in cylindrical tubing of circular cross-section subjected to a uniform suction through the walls. This study has made it possible to find a relationship giving the friction coefficient at the wall in terms of the amount of local suction and of the longitudinal static pressure gradient. A method for calculating the Reynolds tensions from the pressure measurements has been devised. An experimental system has been developed. Pressure measurements have been made. By using experimental results it has been possible to obtain a semi empirical expression for the friction coefficient at the wall, in terms of the amount of suction of the inlet Reynolds number, and of the abscissa. (author) [French] Une etude theorique de refoulement turbulent pleinement developpe dans une conduite cylindrique de section circulaire soumise a une aspiration parietale uniforme a ete entreprise. Elle a permis de trouver une relation donnant le coefficient de frottement a la paroi en fonction du taux d'aspiration local et du gradient de pression statique longitudinal. Une methode de calcul des tensions de Reynolds a partir des mesures de pression a ete etablie. Un dispositif experimental a ete realise et mis au point. Des mesures de pression ont ete effectuees. L'utilisation des resultats experimentaux a permis d'obtenir une expression semi-empirique du coefficient de frottement a la paroi en fonction du taux d'aspiration, du nombre de Reynolds d'entree et de l'abscisse. (auteur)
1969-07-01
Void fraction measurements were made in two phase flow boiling systems at high pressures in a uniformly heated, rectangular channel with a high aspect ratio. The local void fraction values were calculated from measurements of the absorption of a thin collimated X-ray beam (2 mm x 0.05 mm). The mean void fraction in a horizontal section results from integration of the local values across the section. At a fixed measuring station the quality and- void fraction were varied by changing the heat flux, flow rate and pressure systematically. Two channels were used differing in length and thickness (150.8 cm x 5.3 cm x 0.2 cm and the significant features of this study are: -1) The void fraction measurements are among the first obtained at such high pressure (80 to 140 kg/cm{sup 2}); -2) In the experimental region under consideration the measurements are systematic and numerous enough to allow accurate interpolations: mass velocity from 50 to 220 g/cm{sup 2}.s, heat flux from 40 to 170 W/cm{sup 2} and calculated steam quality from -0.2 to 0.2; -3) Many tests were performed under local boiling conditions with the mean temperature of the fluid below the saturation temperature; and -4) These results were compared to the predictions of certain models presented in the literature and simple empirical formulae were developed to fit the experimental results. (author) [French] Des mesures de taux de vide ont ete effectuees sur un ecoulement eau-vapeur a haute pression dans un canal vertical, de section rectangulaire tres allongee et chauffe a flux uniforme. Les valeurs du taux de vide local sont obtenues a partir des mesures de l'absorption d'un faisceau de rayons X finement collimate (2 mm x 0,05 mm). La valeur du taux de vide moyen dans une section droite s'en deduit par integration. Cette section droite ou sont realisees les mesures est fixe et, a pression, debit et flux donnes, les variations du titre et du taux de vide sont obtenues par variations de l'enthalpie d'entree. Deux geometries ont ete etudiees differant par la longueur et l'epaisseur (150,8 cm x 5,3 cm x 0,2 cm et 100,8 cm x 5,3 cm x 0,28 cm). Cette etude presente les caracteres suivants: - 1) Les distributions du taux de vide local sont parmi les premieres obtenues a de telles pressions (80 a 140 kg/cm{sup 2}); - 2) Dans le domaine considere les mesures sont suffisamment systematiques et nombreuses pour permettre des interpolations precises: vitesse massique de 50 a 220 g/cm{sup 2}.s, flux thermique de 40 a 170 W/cm{sup 2}, titre dans la section de mesures de -0,2 a +0,2; - 3) De nombreux essais ont ete realises en ebullition locale, lorsque la temperature moyenne du fluide est inferieure a la temperature de saturation; et - 4) Les resultats obtenus ont permis de tester certains modeles existant dans la litterature et de proposer des formules empiriques simples adaptees aux conditions experimentales considerees. (auteur)
Polarization of Bremsstrahlung; Polarisation du rayonnement de freinage
1957-07-01
The numerical results for the polarization of Bremsstrahlung are presented. The multiple scattering of electrons in the target is taken into account. The angular-and photon energy dependences are seen on the curves for an incident 25 MeV electron energy. (Author) [French] Le taux de polarisation d'un spectre de rayonnement de freinage est calcule pour une cible d'epaisseur finie en tenant compte de la diffusion multiple des electrons dans la cible. Les courbes sont tracees pour les electrons incidents d'energie 25 MeV, pour differentes energies de photons, et a differents angles. (auteur)
2000-05-15
The recycling rate of plutonium and uranium are: from the whole of the plutonium separated from the spent fuel ( inferior to 1% of the nuclear matter content) attributed to France is under 50% (under 42 tons on 84 tons); from the whole of plutonium produced in the French reactors is less than 20% (42 tons on 224 tons); from the whole of the uranium separated from spent fuels attributed to France is about 10 % (1600 tons on 16000 tons); from the whole of the uranium contained in the spent fuel is slightly over 5%. (N.C.)
Accidents du travail et mesures de prvention Anne 2003
Ce rapport prsente les statistiques relatives aux accidents du travail pour lanne 2003 pour les membres du personnel CERN et du personnel entreprise. Il fournit les taux de frquence et de gravit, la rpartition des accidents par cause et par lsion. Ce rapport prsente galement une synthse de lanalyse des accidents les plus graves et des recommandations associes.
Accidents du travail et mesures de prvention -Anne 2006
Ce rapport prsente les statistiques relatives aux accidents du travail pour lanne 2006 pour les membres du personnel CERN et du personnel entreprise. Il fournit les taux de frquence et de gravit, la rpartition des accidents par cause et par lsion. Ce rapport prsente galement une synthse de lanalyse des accidents les plus graves et des recommandations associes.
Accidents du travail et mesures de prvention - Anne 2004
Ce rapport prsente les statistiques relatives aux accidents du travail pour lanne 2004 pour les membres du personnel CERN et du personnel entreprise. Il fournit les taux de frquence et de gravit, la rpartition des accidents par cause et par lsion. Ce rapport prsente galement une synthse de lanalyse des accidents les plus graves et des recommandations associes.
Accidents du travail et mesures de prevention - Annee 2005
Ce rapport prsente les statistiques relatives aux accidents du travail pour lanne 2005 pour les membres du personnel CERN et du personnel entreprise. Il fournit les taux de frquence et de gravit, la rpartition des accidents par cause et par lsion. Ce rapport prsente galement une synthse de lanalyse des accidents les plus graves et des recommandations associes.
2008-01-01
ObjectifLe traitement endoscopique du reflux vesico-ureteral est reconnu comme etant une alternative fiable pour la prise en charge des reflux vesico-ureteraux, notamment de bas grade (taux de reussite
Accidents de travail et mesures de prevention - Annee 2001
Ce rapport prsente les statistiques relatives aux accidents du travail pour lanne 2001 pour les membres du personnel CERN et les entreprises. Il fournit galement des analyses et recommandations relatives lensemble des accidents et met en vidence lvolution des taux de frquence et de gravit, la rpartition des accidents par cause et par lsion. Ce rapport montre aussi des rsums de rapports denqute daccidents. Pour le personnel CERN, le nombre daccidents hors trajet est en rgression -40 % pour le taux de frquence et -75 % pour le taux de gravit. Pour le personnel des entreprises hors projet LHC, les rsultats relatifs aux accidents de trajet sont en nette amlioration, notamment le taux de gravit - 50%. Pour le personnel LHC gnie civil, les rsultats en gnral sont en amlioration avec -18% pour le taux de frquence et 23% pour le taux de gravit. Par contre, la gravit des accidents de trajet sest dgrade pour le personnel CERN avec une hausse denviron un facteur 5 pour le taux de gravit. Alors quentre 2000 et 1999, la tendance tait inverse, cest dire lamlioration. Le taux de gravit navait pas atteint une valeur aussi leve depuis 1994, anne pour laquelle il valait 0.07. Pour lensemble des entreprises hors projet LHC et installation LHC, un travail sur lamlioration des oprations de manutention et de manipulation manuelles pourra tre effectu. En effet, ces oprations constituent la 1re cause des accidents avec une contribution denviron 30% . Pour lensemble des personnes travaillant au CERN, une sensibilisation particulire sur la protection des mains pourra tre faite car il sagit l du 1er sige des lsions pour toutes les catgories de personnel.
1967-07-01
The authors give the results of a series of experiments on metabolism of ingested iodine-131 in adult sheep under lactation; the measurement were carried out over a number of years from 1961 to 1966. The work was concerned initially with the fixation of iodine 131 in the thyroid gland, with the calculation of radiation doses absorbed and with ways of showing up any possible radiation damage in the gland. The modes of absorption of iodine 131 and its elimination through milk, urine and the faeces were then considered. Finally, a last chapter is devoted to changes in the radioactivity of the blood and of the milk, to variations of the PBI level of the blood serum as to different methods for measuring this level. (authors) [French] Les auteurs rapportent les resultats d'une serie d'experimentations relatives au metabolisme de l'iode 131 ingere chez la brebis adulte en lactation, et qui se sont etalees sur plusieurs annees, de 1961 a 1966. Les etudes ont porte d'abord sur les aspects de la fixation de l'iode 131 dans la thyroide, avec le calcul des doses de rayonnements absorbees et les moyens de mettre en evidence les radiolesions eventuelles de la glande. Ensuite ont ete traitees les modalites de l'absorption de l'iode 131 et de son elimination par le lait, les urines et les feces. Enfin un dernier chapitre a ete consacre a l'evolution de la radioactivite du sang et du lait, aux variations ainsi qu'aux divers moyens d'evaluation du taux de PBI du serum sanguin. (auteurs)
2010-01-01
Entre 1988 et 2008, 64 transplantations du rein ont ete effectuees chez 58 enfants. L'age moyen etait de 10,8 ans. 22 % des enfants presentaient des vaisseaux multiples. Les complications ont ete etudiees sur 2 periodes successives de 10 ans (n = 41 pour la 1ere periode et n = 23 pour la 2nde periode). 14 patients (22 %) ont presente des complications chirurgicales. Les complications urologiques concernaient 14 % des complications (urinomes, stenoses ureterales, reflux vesico-ureteral ou calcul) tandis que les complications vasculaires concernaient 11 % des complications. La population des enfants de moins de 6 ans a eu un taux de complications plus important (50 %), avec en majorite des complications vasculaires (33 %). Entre 1988 et 1997, 17 % des transplantes ont eu des complications co...
Measurement of effective renal plasma flow (ERPF) with 123I-orthoiodohippurate (I-123-OIH)
1996-01-01
We evaluated the necessity of attenuation correction for calculating effective renal plasma flow (ERPF) using I-123-orthoiodohippurate (OIH), an agent introduced recently to replace I-131-OIH. From a kidney phantom experiment, the attenuation coefficient (mu) for I-123-OIH in the human body was determined as 0.1262 cm-1. I-123-OIH renal scintigraphy was performed in 23 patients with urinary diseases with blood sampling for calculation of ERPF by Tauxe's method. Calculated renal uptake, with or without attenuation correction, was compared with ERPF determined by Tauxe's method. There was good correlation between renal uptake without attenuation correction and ERPF obtained by Tauxe's method (r=0.737), while much better correlation was found between attenuation-corrected renal uptake and ERPF calculated by Tauxe's method (r=0.816). ...
1964-07-01
This report examines the various fuel handling systems which presently seem feasible for a fast power reactor. It tries to point out the advantages and / or the the disadvantages and the fabrication problems for each solution involved and makes, a tentative to evaluate the time required for a fuel loading and / or unloading operation. One has investigated the influence of the maximum allowable irradiation, the number of of shut-downs, the power distribution shape within the core on the storage capacity needed, the load factor expected and the average irradiation obtained. (authors) [French] On a examine dans ce rapport les differents systemes de manutention, qui semblent actuellement realisables pour un reacteur a neutrons rapides de puissance, en essayant de faire ressortir les avantages, les inconvenients et les difficultes de realisation de chaque systeme, et de chiffer les temps de manutention auxquels ils conduisent. On a aussi regarde l'influence des variations du taux d'irradiation maximal,de la cadence des arrets ou de la forme du flux dans le coeur du reacteur, sur la capacite du stockage, le taux de disponibilite et le taux d'irradiation moyen. (auteurs)
2010-01-01
Rsum Cet article offre un aperu des objectifs de lUnion europenne, des dveloppements lgislatifs actuels au niveau communautaire et de la jurisprudence de la Cour de Justice de lUnion europenne en matire de conciliation entre vie professionnelle, vie prive et vie familiale. Alors que le taux demploi des femmes atteindra en moyenne probablement lobjectif fix dans le cadre de la Stratgie de Lisbonne pour 2010, le partage entre femmes et hommes des tches domestiques et des charges familiales reste ingal. Les politiques de lUnion visent principalement stimuler une augmentation du taux demploi des femmes, en particulier pour prvenir le manque de forces de travail en raison du vieillissement de la population. Malgr un cadre lgislatif important ...
1968-07-01
In natural uranium fuelled reactors, it is important to know the initial conversion ratio, i.e. the ratio of uranium 238 absorption to uranium 235 destruction. The separation of absorption products from fission products is a difficult feature in the measurement of the conversion ratio. A physical method was chosen, the {gamma}{gamma} coincidence technique which uses the properties of the decay scheme of neptunium 239 and allows the neptunium activity to be separated from the fission product activity, with some corrections. Detectors of natural uranium are used. The accuracy obtained in the measurements is of the order of 2%. (authors) [French] Dans les reacteurs a uranium naturel, il est important de connaitre le facteur de conversion initial, c'est-a-dire le rapport entre le taux de capture de l'uranium 238 et le taux de destruction de l'uranium 235. Le point delicat dans la mesure du facteur de conversion est la separation entre produits de capture et produits de fission. On a choisi d'utiliser une methode physique, par coincidences {gamma}{gamma} qui, utilisant les particularites du schema de decroissance du neptunium 239, permet de separer, moyennant certaines corrections, l'activite du neptunium de celle des produits de fission. On utilise des detecteurs de meme nature que le combustible du reacteur etudie, afin de modifier au minimum les caracteristiques du combustible, La precision obtenue est de l'ordre de 2%. (auteurs)
1996-12-31
We have set up a membrane for the electrochemical coating of {sup 235}U and {sup 237}Np in a double fission chamber (called D F C) and have measured the {sup 235}U / {sup 237}Np fission rate by irradiation in a speed moderating solid armature in KUCA.
Accidents du travail et mesures de prvention$$bAnne 2002
Ce rapport prsente les statistiques relatives aux accidents du travail pour lanne 2002 pour les membres du personnel CERN et les entreprises. Il fournit galement des analyses et recommandations relatives lensemble des accidents et met en vidence lvolution des taux de frquence et de gravit, la rpartition des accidents par cause et par lsion. Ce rapport montre aussi des rsums de rapports denqute daccidents. Pour le personnel CERN, le taux de gravit poursuit une diminution notable Tg (-59%) et Tg (-66%) des accidents hors trajet. Pour le personnel des entreprises hors projet LHC, on constate une diminution des taux de frquence Tf (-48%) et gravit Tg (-39%) qui taient en lgre hausse lanne dernire. De plus, il ny a eu aucun accident de trajet avec arrt en 2002. Pour le personnel LHC gnie civil, les rsultats poursuivent leur amlioration la fois sur le plan frquence des accidents (-30%) et sur le plan gravit (-51% ). Par contre, pour le personnel CERN le taux de frquence des accidents de trajet poursuit sa hausse Tf (+106%). Le nombre daccidents de trajet a doubl entre 2001 et 2002 (16 en 2002 contre 8 en 2001) . Pour lensemble des entreprises hors projet LHC, LHC gnie civil et CERN, un travail sur lamlioration des oprations de manutention et de manipulation manuelles pourra tre effectu. En effet, ces oprations constituent la 1re cause des accidents avec une contribution denviron 30% . Par ailleurs, une sensibilisation particulire sur la protection des mains pourra tre galement faite car il sagit l du 1er sige des lsions pour toutes ces catgories de personnel.
1967-07-01
This work deals with the reliability of automatic control systems which can be applied to nuclear reactors. The calculations which have been carried out make possible the orientation of the choice of the scheme and of the elements used, as a function of the operational safety. Two types of redundancy are studied (sequential and parallel) showing the importance of the detection of active and passive failures, and of the maintenance. The failures rates coefficients for the elements used in a automatic control system design have been calculated using the data given by the 'R.A.D.C. Reliability Note book'. (author) [French] Cette etude traite de la fiabilite des systemes de pilotage automatique qui peuvent etre utilises sur les reacteurs nucleaires. Les calculs faits dans cette etude permettent d'orienter le choix d'un schema et des elements utilises dans ce schema en fonction de la securite de fonctionnement. On examine les deux types de redondance (sequentielle et parallele) mettant en evidence l'importance de la detection des pannes actives et passives et de la maintenance. Les taux de defaillance pour les elements utilises dans un schema de pilotage automatique ont ete determines a partir des donnees du 'R.A.D.C. Reliability Note Book'. (auteur)
1969-07-01
Radioprotective properties of imidazole and benzimidazole have been proved in previous works. In this study, authors try to demonstrate radioprotective action of these compounds in comparison with cysteamine upon the hematopoietic system after lethal X-irradiation. Results show: no drastic variations of hematologic constants (hemoglobin concentration and hematocrit value) after intraperitoneal injection of radioprotective compounds apart certain apparent reactions with the heterocyclic compounds; the better radioprotective action of benzimidazole. Twenty five days after irradiation, hemoglobin concentration and hematocrit of radio protected mice return to normal values. (author) [French] Les proprietes radioprotectrices de l'imidazole et du benzimidazole ayant ete demontrees dans de precedents travaux, les auteurs se sont attaches a etudier l'action de ces produits sur le systeme hematopofetique en comparaison avec celle de la cysteamine, apres une irradiation a dose letale. A l'aide des criteres choisis, les resultats demontrent: qu'en dehors de certaines reactions apparentes, succedant a l'injection intraperitoneale des heterocycles azotes, les constantes hematologiques (taux d'hemoglobine et valeur hematocrite) ne sont que legerement modifiees; la superiorite du benzimidazole sur les autres produits utilises. Enfin, le vingt-cinquieme jour apres irradiation, les souris protegees par les heterocycles azotes ont un taux d'hemoglobine et une valeur hematocrite tout a fait normaux. (auteur)
1962-07-01
The foliar absorption of phosphates labelled with {sup 32}P and applied with or without magnesium sulfate on the first leaf of pumpkin seedlings have been studied. The magnesium sulfate applied with the phosphate reduces plainly the absorption rate of {sup 32}P. (O.M.) [French] Nous avons etudie l'absorption foliaire de phosphates marques au {sup 32}P appliques, avec et sans sulfate de magnesium, sur la premiere feuille de jeunes plants de potirons. Le sulfate de magnesium applique avec le phosphate diminue nettement le taux d'absorption du {sup 32}P. (auteur)
P451 - Une pan cytopenie profonde revelant une carence en vitamine B12
2010-01-01
Objectif: Mettre le point sur une cause rare de pan cytopenie chez l'enfant. Observation: II s'agit d'une fille agee de 12 ans, sans antecedents notables, hospitalisee pour une pan cytopenie decouverte sur un hemogramme pratique devant une paleur et un ictere. Le bilan d'admission montrait une anemie severe a 2,9g/dl, une leucopenie a 2700/mm^3 et une thrombopenie a 78 000/mm^3. Le myelogramme montrait une moelle moyennement riche avec erythroblastose macrocytaire, des signes d'asynchronisation de maturation nucleo cytoplasmique, des corps de Joly et des mitoses anormales. L'ensemble evoquait une pan cytopenie carentielle. Le dosage vitaminique a mis en evidence une baisse du taux de vitamine B12 avec un taux normal des folates. L'evolution sous suplementation en vitamine B12 etait favorab...
Effects of rock fragments on water movement and solute transport in a Loess Plateau soil
2009-01-01
Resume On observe la presence de concretions carbonatees d'origine pedogenetique dans les sols de Plateau Loessique chinois. La presence de ces petits fragments de roche peut avoir des effets importants sur la densite apparente du sol, sa structure et ses proprietes de stockage de l'eau, ainsi que sur les mecanismes de transfert de l'eau et des solutes. Nous avons etudie l'influence de proportions ponderales Rw variables de fragments de roche dans un sol (0, 10 20, 30, 40, 50, et 60 %) sur l'infiltration, la conductivite hydraulique a saturation Ks et le transport de solutes. Le taux d'infiltration et la conductivite hydraulique a saturation decroissent initialement avec la croissance de la teneur en fragments, jusqu'a des valeurs minima obtenues pour un taux de 40 %, puis recroissent. Les...
2005-06-28
We calculate the height dependence of recombination energies, polarization and radiative lifetimes of the optical transitions of various excitonic complexes: neutral excitons (X^0), negatively- (X^-) and positively-charged (X^+) trions, and biexcitons (XX^0) in lens-shaped, self-assembled In_0.6Ga_0.4As/GaAs quantum dots. By using an atomistic pseudopotential method combined with the configuration-interaction method, we predict the following. (i) The recombination energy of the lowest transition of X^- blue-shifts as height increases, whereas that of X^+ red-shifts. Remarkably, the recombination of XX^0 shows a red-shift at small heights, reaches a maximum shift, and then blue-shifts for taller dots. (ii) Changes in dot height lead to a bound-to-unbound crossover for X^-, X^+ and XX^0. (iii) When considering the [110] and [1\\bar{1}0] directions, the lowest transitions of X^0 and XX^0 manifest [110] vs [1\\bar{1}0] in-plane polarization anisotropy that switches sign as a function of height as well as alloy randomness. $X^-$ and $X^+$ show transitions with negligible polarization anisotropy regardless of height. (iv) The ground state of X^0 is split in a low-energy pair that is forbidden (dark) and a high-energy pair that is allowed; thus, at T=0K the radiative lifetime \\tau(X^0) is long (~ ms) due to the dark exciton. On the other hand, at T=10K, \\tau(X^0) decreases moderately as height increases and its magnitude ranges from 2-3ns. The ground state of X^- and X^+, and that of XX^0 is allowed (bright); so, \\tau(X^-), \\tau(X^+) and \\tau(XX^0) are fast (~ ns) even at T=0K. These radiative lifetimes depend weakly on height. In addition, \\tau(X^-) ~ \\tau(X^+) ~1.1ns, while \\tau(XX^0)~0.5ns$. We compare our predictions with available spectroscopic data.
1962-07-01
This machine is designed to control the band-towels in the form of 40 meters bands equipping the 'Essuimatic' distributors. It controls automatically the {alpha} and {beta}-{gamma} activity. The towel is driven by motors and passes under Geiger-Muller counters and then between zinc sulphide scintillators in conjunction with photomultipliers. Two distinct counting systems measure the total activity deposited on the cloth and, in order to give an idea of the distribution of this activity, count also the number of marks, that is, the number of times that the counting rate of the probes is above a certain value. After the passage of the cloth it is thus possible to know whether the count corresponding to the whole band is greater than that due to just the counter movement, and also whether this counting rate has not occasionally been greater than the average rate; it is thus possible to detect weak local contamination which could have been missed in an overall measurement of the cloth. (authors) [French] Cette machine est destinee a controler les linges essuie-mains sous forme de bande de 40 metres de longueur equipant les distributeurs 'ESSUIMATIC'. Elle effectue automatiquement un controle en {alpha} et en {beta}-{gamma}. Le linge entraine par un moteur passe. sous des compteurs Geiger-Muller, puis entre des scintillateurs au sulfure de zinc associes a des photomultiplicateurs. Deux chaines de comptage distinctes comptent l'activite totale deposee sur le linge et, en outre, pour donner une idee de la repartition de cette activite, elles comptent le nombre de taches, c'est-a-dire le nombre de fois que le taux de comptage des sondes est superieur a une certaine valeur. A la fin du passage du linge, il est donc possible de connaitre si le comptage correspondant a toute la bande est superieur a celui du au mouvement propre seul des compteurs et egalement de savoir si parfois ce taux de comptage n'a pas ete superieur au taux de comptage moyen, ce qui permet de detecter de faibles contaminations localisees qui auraient pu passer inapercues dans le comptage global de toute la bande. (auteurs)
1955-07-01
Description of the conditions of plutonium, fission products and of uranium separation by selective extraction of the nitrates by organic solvent, containing a simultaneous extraction of plutonium and uranium, followed by a plutonium re-extraction after reduction, and an uranium re-extraction. The rates of decontamination being insufficient in this first stage, we also describes the processes of decontamination permitting separately to get the rates wanted for uranium and plutonium. Finally, we describes the beginning of the operation that consists in a nitric dissolution of the active uranium while capturing the products of gaseous fission, as well as the final concentration of the products of fission in a concentrated solution. (authors) [French] Description des conditions de separation du plutonium, des produits de fission et de l'uranium au moyen d'une extraction selective des nitrates par solvant organique, comprenant une extraction simultanee du plutonium et de l'uranium, suivie d'une reextraction du plutonium apres reduction, et d'une reextraction de l'uranium. Les taux de decontamination etant insuffisants dans ce premier stade, on decrit egalement les processus de decontamination permettant separement d'obtenir les taux desires pour l'uranium et le plutonium. Enfin, on decrit aussi le debut de l'operation qui consiste en une dissolution nitrique de l'uranium actif en captant les produits de fission gazeux, ainsi que la concentration finale des produits de fission sous forme de solution concentree. (auteurs)
Power calibration of Proserpine (1960); Etalonnage en puissance de proserpine (1960)
1960-07-01
The power of a homogeneous reactor can be determined if the fission rate at one point is known, and also the flux chart throughout the whole volume of fuel. By applying this method to Proserpine, the following operations have been carried out: 1) determination of the fission rate at a point by means of a miniature zirconium fission chamber, with absolute counting of the plutonium deposit in a low-geometry {alpha} chamber; 2)establishment of a flux chart by activation of gold bands, without contamination of gold by plutonium. (author) [French] On peut determiner la puissance d'un reacteur homogene si l'on connait le taux des reactions de fission en un point, et la carte du flux dans tout le volume du combustible. Cette methode, appliquee a la pile Proserpine, a conduit aux manipulations suivantes: 1) determination du taux de reactions en un point, grace a une chambre a fission miniature en zirconium, dont le depot de plutonium a fait l'objet de comptages absolus dans une chambre {alpha} a faible geometrie; 2) etablissement d'une carte de flux, par activation de bandes d'or, sans contamination de l'or par le plutonium. (auteur)
Large real exchange rate movements, firm dynamics, and productivity growth
2008-01-01
Abstract. This paper examines the influence of large real exchange rate movements on firm turnover and production scale, and the contribution of these decisions to productivity growth. Our theoretical model predicts that home currency appreciations cause firm closure and reduce surviving firms' exports while boosting domestic sales. The net effect on sales and productivity therefore depends on changes in domestic sales and exports. Taiwanese firm-level data are used to test these predictions. The results show that real currency appreciations lead to scale expansion of surviving firms which in turn raises productivity. Our findings suggest the existence of a significant scale effect. Changements importants dans les mouvements du taux de change reel, dynamique de la firme, et croissance de l...
L'anemie de la polyarthrite rhumatoide
2010-01-01
L'anemie rhumatoide est un exemple typique de l'anemie des maladies chroniques. Elle s'oppose aux autres anemies, dont les anemies ferriprives ou iatrogenes. Le profil hematologique est donne : anemie normochrome, normocytaire, ou moins souvent microcytaire, aregenerative avec thrombocytose, transferrinemie normale ou diminuee, coefficient de saturation de la transferrine abaisse, ferritinemie normale ou elevee, taux du recepteur soluble de la transferrine (RsTf) non augmente (contrairement a l'anemie par carence martiale), rapport RsTf/logarithme de la ferritine
2007-01-01
Abstract. Production and marketing lags in agri-food supply chains often force agricultural producers and food processors to commit to output targets before prices and exchange rates are realized. A theoretical model illustrates how the processor's degree of risk aversion and domestic sales may cause the relationship between volatility of the exchange rate and exports to be non-monotonic. The relationship between exchange rate volatility and Quebec pork exports to the United States and Japan is investigated using linear and non-linear estimation methods. The results support the hypothesis that the relationship between exports and volatility is non-monotonic. Est-ce que les exportations sont une fonction monotone de la volatilite du taux de change? Le cas des exportations de viande porcine ...
2010-01-01
This paper describes the main features of the accelerated test procedures used to determine reliability data of microelectronics devices used in terrestrial environment.This paper focuses on the high energy particle test that could be performed through spallation neutron source or quasi-mono-energetic neutron or proton. Improvements of standards are illustrated with respect to the state of the art of knowledge in radiation effects and scaling down of microelectronics technologies. (authors)
1995-11-01
{sup 99m}Tc-mercaptoacetyltriglycine (MAG3) is a new agent for dynamic renal scintigraphy. It provides not only superior quality of imaging to conventional agents such as {sup 131}I-orthoiodohippurate or {sup 99m}Tc-demethylenetriaminepantaacetic acid but also quantification of renal function as do the latter agents. The aim of the present study was to evaluate the value of the tubular extraction rate (TER) using {sup 99m}Tc-MAG3 calculated by Bubeck`s method, a simple technique for quantifying renal function. In 31 patients with renal disorders, we compared the TER thus obtained with laboratory data, plasma paraaminohippurate clearance, effective renal plasma flow calculated by Tauxe`s method, and plasma {sup 99m}Tc-MAG3 clearance calculated according to the two-compartment model. TER was easily applicable in clinical settings, and showed close parallels with the other indexes of renal function. We believe, therefore, that it can serve as a useful parameter of renal function. (author).
2010-01-01
L'objectif de ce travail est de determiner la prevalence de l'allergie aux proteines du lait de vache (APLV) chez les nourrissons ages de 0 a 3 ans frequentant les centres de protection maternelle et infantile (PMI). Nous avons realise une enquete basee sur un questionnaire et a porte sur 822 nourrissons frequentant les PMI des 2 communes de la wilaya d'Annaba durant la periode Juin-Octobre 2009. Les resultats obtenus ont montre une prevalence de l'APLV de 4,9 %. Le taux des cas confirmes par un test allergologique est de 3,5 %. La prevalence de l'allergie alimentaire cumulee a atteint un taux de 6,2 %. L'allergene majeur est le lait de vache (78,4 % des cas), suivis des oeufs (9,80 %), fraise (5,9 %) et poisson (2 %). Les manifestations cliniques les plus remarquees sont les symptomes dig...
P488 - Le rhumatisme articulaire a Mayotte
2010-01-01
Objectif: Decrire les aspects epidemiologiques, cliniques et evolutifs du rhumatisme articulaire aigu (RAA) a Mayotte. Materiels et Methodes: Etude retrospective des cas de RAA hospitalises dans le service pediatrique de l'ile entre janvier 2002 et avril 2009. Resultats: Soixante-trois episodes ont ete inclus (46 cas inauguraux et 17 rechutes), soit une estimation basse de l'incidence du RAA sur l'ile de 14,1 cas/an/100000 enfants de 5 a 14 ans. L'age moyen etait de 8,2 ans (3-14 ans). Le taux de cardites aigues etait eleve (64 %) alors que les polyarthrites etaient plus rares (21 %) ; 22 % presentaient un tableau atypique de monoarthrite ; 52 cas (82 %) satisfaisaient les criteres de Jones, 11 etaient des cas probables. Un patient sur trois presentait une cardite severe des le premier epi...
2010-01-01
Objectifs: Le syndrome triple A est une maladie autosomique recessive caracterisee par une insuffisance surrenalienne, une alacrimie, une achalasie et occasionnellement un dysfonctionnement du systeme nerveux autonome. Les mutations responsables se situent au niveau du gene AAAS codant pour la proteine aladin. Sujet: Garcon de 2 ans et demi, issu de parents non consanguins d'origine marocaine, presente des convulsions generalisees prolongees dans un contexte de pyrexie, d'une hypoglycemie et d'hypotension persistante. L'examen physique est normal, il n'y a pas d'hyperpigmentation. Le diagnostic d'insuffisance surrenalienne est etabli sur base de trois dosages de cortisol serique indetectables et d'un taux d'ACTH tres eleve. Un traitement par hydrocortisone est instaure et ajuste en fonctio...
Mningoencphalite Morganella morganii : propos dun cas
2010-01-01
Rsum Il est rare dobserver une infection Morganella morganii du systme nerveux central. Nous dcrivons un premier cas diagnostiqu au Service de neurologie de lhpital universitaire Fann de Dakar au Sngal. Un garon de 12 ans a t hospitalis pour une mningoencphalite aigu. Le scanner tait normal et lanalyse du liquide cphalorachidien (LCR) avait mis en vidence des anomalies cytologiques et biochimiques, ainsi que la prsence de M. morganii. Les srologies VIH et syphilitique taient ngatives et le taux sanguin de lymphocytes CD4 tait de 354/mm3. Un traitement de six semaines par cfotaxime associ la gentamicine a t efficace. Lissue de linfection dpend de nombreux facteurs, tels que la rapidit de mise en oeuvre et la qual...
CL135 - Pyelonephrites aigues et troubles mictionnels : quel est le role du reflux ?
2010-01-01
Objectif: Etude du taux de pyelonephrites aigues(PNA) chez les filles suivies pour une dyssynergie vesico-sphincterienne (DVS). Patients et Methodes: Etude retrospective de 260 patientes avec une DVS entre janvier 93 et janvier 07. 83 avaient un reflux vesico-ureteral associe, 24 un antecedent de reflux opere, 149 une DVS isolee. Resultats: La reeducation vesico sphinterienne par biofeedback a permis la guerison de la DVS dans 92 % des cas. Dans le groupe avec reflux, 65 sur 83 (78 %) ont eu au moins un episode de PNA et 6 ont recidive. Sur 30 scintigraphies renales faites, 21 sont anormales. Dans le groupe sans reflux, 78 sur 149 (56 %) ont eu au moins un episode de PNA et 14 ont recidive. Sur 11 scintigraphies renales faites, 9 sont anormales. 5 enfants ont eu un traitement endoscopique ...
CL069 - Complications du traitement conservateur des traumatismes hepatiques fermes de l'enfant
2010-01-01
But: le traitement non operatoire des traumatismes hepatiques fermes est un gold standard chez l'enfant hemodynamiquement stable, mais il n'est pas denue de complications. Le but de cette etude etait d'evaluer l'incidence, les moyens diagnostiques, le traitement et le devenir de ces complications. Methodes: Etude retrospective incluant les patients de moins de 16 ans admis au CHU de Montpellier pour un traumatisme ferme du foie sur une periode de 10 ans. Resultats: 51 enfants ont beneficie d'une approche non chirurgicale, avec un taux de succes de 94,1 % (48/51). Trois patients (5,9 %) ont presente un total de 13 complications directement liees a leurs hepatiques. Les complications hepatiques etaient biliaires, hemorragiques, thrombotiques et un syndrome de compartiment. Ces complications ...
2000-07-01
In the present development phase of the SILVA process, the CEA has to calculate the availability of the future SILVA plant. Its production capacity will greatly depend on the reliability of its components. Specific software has been developed to calculate this, basically divided into three parts Database (CRESUS) on the reliability and maintainability of the components gathered into functional groups. Database (REMUS) on continuous degradation laws for their performance. Code (OCTOPUS) on production capacity, containing three models - model of the architecture of the laser, separator and shuttle apparatus. - numerical code to calculate production from the states of the equipment. - model for maintenance scenarios. A complete set of data is processed concerning the failure or survival of actually tested components, or the scaling-up models proposed by the experts. The availability of the future SILVA plant is finally obtained with its production rate and its optimum maintenance policy, comprising curative and preventive maintenance. The entire data chain is organized to be structured, traceable and shared by all the players. At present, data from 15 experimental installations, 50 types of equipment and 221 components are taken into account for compilation of the CRESUS database. Information such as test characteristics, description of events (i.e. preventive component exchange or type of failure, etc.) and description of the version of the components under test, are furnished by the experimenters in user-friendly forms developed with 'Access' software. These data are used to calculate the component failure laws through the history of each. This is followed by the determination of the reliability law parameters and confidence limits for the functional groups, for example the beta and eta parameters of the universal statistical Weibull distribution for the failure rate determined by a maximum likelihood method. This provides information such as Mean Time Before Failure (MTBF) and Mean Time through Repair (MTR). These parameters are saved in specific CRESUS tables and serve as input data for an OCTOPUS calculation. The OCTOPUS code uses 'hybrid simulation' techniques, including the processing of continuous and discrete behaviors in a single model. The SILVA production facility is described by Petri nets according to the same functional analysis as CRESUS. Petri nets are ideal for analyzing complex systems with discrete binary dysfunctional events and to cope with resource sharing. The main originality of our technique is the coupling of a code modeling the physical aspects and the various drifts occurring during the process and the previous discrete model. One interesting feature is the introduction of feedback from the continuous part to the discrete part through operating scenarios which validate or inhibit specific transitions leading to maintenance actions under a set of criteria (yields, instant of failure) specified by the user. The aim of this computation is twofold without feedback, we can estimate the overall efficiency of the plant and focus on the relative impact of individual reliability parameters on this rate, with feedback, we optimize the operation and maintenance strategies to minimize total production costs and identify the operating domain.
1964-07-01
The variations of vertical and temporal distributions of natural radioactivity with geographical location in the lower atmospheric layers are shown. The content of radon and its short lived daughters products are measured. Radon content is measured continually with a new apparatus, the sensibility of which is 0,2.10{sup -11} Ci m{sup -3} i.e. the fiftieth of the mean concentration near the soil, this apparatus allowed us to show that radioactive equilibrium between radon and its daughter products is realised when the atmosphere is stable. Air observations between 0 and 100 meters above the ground point out that radon and its decay products are valuable tracers to mark the stability of the atmosphere. Under very stable nighttime conditions the radon accumulates in the former 30 meters of the air layer, at sunrise it ascends and at 9 o'clock attains 100 meters high. The removal rate of the air in the lower atmosphere is computed from the movement of this radon mass, it is equal to 90 per cent for a summer day. We have show that this radon comes from the soil in which it diffuses by brownian motion the intensity of which varies with the water content of the soil, its value for June 1958 is 6,10{sup -17} Ci cm{sup -2}s{sup -1} and for January 1959 0.2,10{sup -17} Ci cm{sup -2} s{sup -}1. During the year 1958-1959 general mean of flux for the sedimentary soil studied is equal to 3. 8 {+-} 1.3, 10{sup -17} Ci cm{sup -2} s{sup -1} it is identical to the world wide mean computed by H. Israel. In a hilly site in the Morvan, air movements are well marked by this radioactivity. We observed from one hand downslope and up-slope breezes having, respectively, speeds of 0.2 m s{sup -1} and 0.7 m s{sup -1} and from the other hand by night, in the valley and with a light wind favours the stagnation of the air near the ground, a strong increase of the radioactivity which is proportional to the one of the granitic rocks of the region. The radon flux of this soil is 74,10{sup -17} Ci cm{sup -2}s{sup -1} and the radioactivity of the air can attain 1.5,10{sup -8} Ci m{sup -3} that is five times the permissible dose for populations. (author) [French] Une etude des variations de la radioactivite naturelle de l'air dans la basse atmosphere en fonction des parametres meteorologiques et du relief est presentee. Les radionuclides doses sont le radon et son depot a vie courte. La concentration en radon est dosee de facon continue a l'aide d'un nouvel appareil dont la sensibilite atteint 0,2.10{sup -11} Ci m{sup -3} soit le cinquantieme de la teneur moyenne de l'air au voisinage du sol, cet appareil permet de montrer que l'equilibre radioactif entre le radon et ses descendants a vie courte est realise pendant les periodes ou l'atmosphere est stable. Les observations dans l'air entre 0 et 100 metres au-dessus du sol indiquent que le radon et son depot actif sont de precieux traceurs marquant la stabilite de l'atmosphere. En periode d'inversion de temperature, la nuit en general, le radon s'accumule dans les 30 premiers metres de la couche d'air, puis est chasse avec te lever du soleil et passe au niveau de 100 metres a 9 heures du matin. Le taux de renouvellement de l'air de la basse atmosphere est calcule d'apres le mouvement de cette masse de radon, il est de 90 pour cent un jour d'ete. On montre que ce radon provient du sol ou il diffuse par mouvement brownien variant avec la teneur en eau du sol, en juin 1958, il est de 6.10{sup -17} Ci m{sup -2} s{sup -1} et en janvier 1959 de 0,2.10{sup -17} Ci cm{sup -2} s{sup -1}. Pour l'annee 1958-1959, la moyenne generale du degagement de ce terrain sedimentaire est de 3,8 {+-} l,3.10{sup -17} Ci cm{sup -3} s{sup -1}, elle est identique a la moyenne mondiale calculee par H. Israel. Dans un site vallonne du Morvan, les mouvements de l'air sont bien marques par cette radioactivite; on a observe d'une part des brises ascendantes et descendantes ayant des vitesses d'environ 0,2 et 0,7 m s{sup -1} respectivement et d'autre part, la nuit dans la vallee par vent faible favorisant la stagnation de l'air pres du sol, une faible augmentation de la radioactivite proportionnelle a celle du terrain granitique de la region. Le degagement du radon de ce sol est de 74.10{sup -17} Ci m{sup -2} s{sup -1} et la radioactivite de l'air peut atteindre l,5.10{sup -8} Ci m{sup -3} soit 5 fois la dose permise aux populations. (auteur)
O26 Parcours de soins des personnes diabetiques hospitalisees pour infarctus du myocarde en France
2009-01-01
Objectif Comparer la prise en charge de l'infarctus du myocarde (IdM) entre les patients diabetiques et non diabetiques. Patients et methodes A partir de la base nationale du PMSI MCO, les sejours des beneficiaires du regime general de l'assurance maladie avec un GHM d'IdM au premier semestre 2006 ont ete selectionnes. Chacune des hospitalisations a ete chainee avec la base des remboursements de l'assurance maladie, pour les periodes des 6 mois avant et apres. Le diabete a ete defini par une affection de longue duree (ALD) specifique et/ou le remboursement d'un antidiabetique au moins a 3 reprises dans les 6 mois avant et/ou apres. Les taux de prise en charge ont ete ajustes sur l'age et le sexe. Resultats Parmi les 11 671 malades retenus, 2 496 etaient diabetiques (21,4 %). Ces derniers e...
Les problemes de la qualite de l'onde electrique constituent l'une des preoccupations majeures des fournisseurs de l'energie et des organismes specialises en qualite d'energie. Ce sujet a gagne davantage d'ampleur avec l'utilisation ascendante des convertisseurs de l'energie electrique dans la majorite des applications industrielles et domestiques. Dans le cadre de cette these, on s'interesse plus particulierement au type des convertisseurs alternatif/continu, dont le fonctionnement adequat implique la parfaite regulation du bus DC de tension, l'attenuation des harmoniques de courants, la compensation de l'energie reactive et la maximisation du rendement energetique. Ces differents criteres doivent etre maintenus pour diverses conditions de fonctionnement, c'est-a-dire independamment des variations parametriques auxquelles le systeme peut etre sujet. Il s'avere donc indispensable d'adopter des techniques de commande efficaces, ce qui passe par une modelisation correcte du convertisseur. L'optimisation du nombre de capteurs dans le circuit est egalement un facteur cle a prendre en consideration.
1967-07-01
The core of the research reactor Pegase, in operation at the Cadarache Nuclear Research Centre since 1983, contains fuel elements made from rolled plates of an aluminium-enriched uranium alloy whose characteristics have been changed several times. This report describes the modifications which have been made to these fuel elements with a view both to improving the technical qualities of the reactor and to decreasing its operational costs. Special attention is paid to the neutron aspects of the topic and in particular to the problem of the long-term modification of the reactivity. The 1966 results (30 per cent burn-up associated with only slight movement of the control rods) are particularly satisfying and can probably still be improved in the future. (authors) [French] Le coeur du reacteur de recherche Pegase, en fonctionnement au Centre d'Etudes Nucleatces de Cadarache depuis 1963, utilise des elements combustibles a plaques laminees d'alliage uranium enrichi et aluminium, dont les caracteristiques ont ete modifiees a plusieurs reprises. Ce rapport indique les modifications qui ont ete apportees a ces elements dans le double but d'ameliorer les qualites techniques du reacteur et de diminuer son cout de fonctionnement. On insiste surtout sur l'aspect neutronique du sujet, et notamment sur les problemes d'evolution a long ferme de la reactivite. Les resultats obtenus en 1966 (taux de combustion de 30 pour cent associe a de faibles mouvements des barres de controle) sont particulierement satisfaisants et pourront etre encore ameliores a l'avenir. (auteurs)
volution des infrastructures techniques du centre de calcul en vue du LHC (2001-2009)
Au milieu de lanne 1999, le projet de renforcement des infrastructures techniques du Centre de Calcul a t lanc afin de rpondre aux besoins des Fermes de Calculs destines au traitement et stockage des donnes des expriences du LHC. En 2008, premire anne de fonctionnement du LHC pleine luminosit, les Fermes de Calculs devraient occuper 2500 m2 et consommer une puissance lectrique de 2.5 MW. Les infrastructures techniques du btiment datant des annes 70 ne permettaient pas de rpondre aux nouvelles demandes tant en termes de puissance que de disponibilit des services. Aprs avoir prsent les particularits de la charge, compose exclusivement dalimentations dcoupage monophases, cet article dcrit successivement les exigences de lutilisateur en terme de continuit de fonctionnement du Centre de Calcul, les options tudies pour y rpondre et la solution retenue. La situation du projet est ensuite prsente: les tapes ralises, en cours et venir.
2010-01-01
Rsum Les tumeurs stromales gastro-intestinales (GIST) sont les noplasies msenchymateuses les plus frquentes du tube digestif. Latteinte gastrique est la plus courante (6070 %), suivie de celle de lintestin grle (2030 %). Les GIST possdent des caractristiques immunohistochimiques spcifiques, essentielles au diagnostic. Prs de 95%des GIST expriment le c-kit (antigne CD117), un rcepteur transmembranaire tyrosine-kinase dont lactivation dclenche la prolifration cellulaire. La chirurgie est le traitement de choix des tumeurs rscables, alors que le traitement standard des tumeurs non rscables est ladministration dimatinib (Glivec), un inhibiteur comptitif de c-kit/PDGFRA. Le taux de rponse au traitement par imatinib est denviron 8...
1961-07-01
This paper describes the results obtained, at laboratory scale, during the study of the incorporation of fission products into glasses and synthetic micas. The rate of leaching of fission products from the glass and their volatility during firing were measured. A hot cell was built to complete these results. (author) [French] Ce rapport resume le resultat des etudes faites en laboratoire (activite de l'ordre du millicurie) sur l'incorporation des produits de fission dans des verres et micas synthetiques. On a mesure le taux de lixiviation des produits de fission et leur volatilisation au cours de la cuisson. Une cellule chaude a ete installee pour completer ces resultats au moyen d'essais realises avec une activite superieure. (auteur)
Qualitative properties of monostable pulsating fronts: exponential decay and monotonicity
2008-01-01
ResumeDans cet article, nous montrons diverses proprietes qualitatives de fronts progressifs pulsatoires dans des milieux periodiques, pour des equations de reaction-diffusion avec des non-linearites de type Kolmogorov-Petrovsky-Piskunov ou, plus generalement, des non-linearites de type monostable. Outre les proprietes de monotonie, la partie de larticle est consacree a letude du comportement exponentielle des fronts lorsquils approchent leur etat limite instable. Dans le cas monostable general, nous determinons lequivalent logarithmique des fronts. Pour des vitesses non critiques, le taux de decroissance est le meme que dans le cas KPP. Ces resultats generalisent egalement des resultats connus dans le cas homogene ou dans le cas ou lequation est invariante par translation dans la directio...
1956-07-01
It is possible to reduce boron element into fine powder by means of a mortar and pestle made of sintered boron carbide, the ratio of boron carbide introduced being less than one per cent. Boron element at our disposal is made of sharp edged, dark brown, little grains of average size greater than 5 {mu}. Grain sizes smaller than 1{mu} are required for applying thin layers of such boron. (author) [French] Il est possible de pulveriser finement du bore element au moyen de mortier et pilon en carbure de bore fritte, le taux de carbure de bore introduit etant inferieur a 1 pour cent. Le bore element dont nous disposons est constitue de petits grains brun fonce, a aretes vives, de dimension moyenne superieure a 5 {mu}. L'application de ce bore en couches minces demande des grains de dimensions inferieures a 1 {mu}. (aute0008.
Placenta accreta: frquence, diagnostic prnatal, prise en charge
2010-01-01
Rsum En quelques dcennies, lincidence des placentas accretas sest considrablement majore (1/2 0002 500 naissances environ). Cette augmentation est corrle laugmentation du taux de csarienne dans les 30 dernires annes. Lchographie 2D est un examen utile pour le diagnostic des placentas accretas. Le critre chographique le plus performant est les lacunes intraplacentaires. Labsence isole dun liser hypochogne entre le placenta et le myomtre a une faible sensibilit et valeur prdictive positive. Le doppler nergie en 3D est un outil utile en complment de lchographie 2D. La prsence dau moins deux critres chographiques permet daugmenter la performance de lchographie 2D ou 3D et de diminuer le nombre de faux-positif...
P186 - Le deficit en vitamine B12 cause rare de l'anemie de l'enfant
2010-01-01
L'interet c'est de souligner l'importance du dosage de la vitamine B12 en cas d'anemie associee a d'autres signes notamment neurologiques chez l'enfant. Nous rapportons l'observation d'un nourrisson age de 4 mois allaite exclusivement au sein, admis pour vomissements chroniques installes depuis l'age de 3 mois avec stagnation ponderale. L'examen clinique a revele une hypotonie, un retard ponderal -2DS et une paleur cutaneomuqueuse. L'hemogramme a objective une pancytopenie. Un medullogramme realise a montre une megaloblastose. Les dosages de la vitamine B12 chez le nourrisson ainsi que chez la mere ont revele des taux tres effondres. On a conclu a un deficit carentiel. Le nourrisson est mis sous traitement substitutif et la maman est adressee en medecine interne pour bilan etiologique de s...
2009-01-01
Conventional radiotherapy (R.T.) in breast cancer treatment includes a total dose of 50 Gy with a 16 Gy-boost in a smaller volume. After mastectomy, radiotherapy of all node-positive patients seems to be applied whatever the positive node number. Modulation of R.T. technique uses the fraction dose, namely through accelerated hypo fractionation regimen in a constant volume. A group of patient with a low risk of recurrence may benefit from this technique. In a smaller irradiated volume, accelerated hypo fractionation still belongs to intensive clinical research evaluating intraoperative R.T., brachytherapy, Mammo-site, and external partial breast irradiation. Intensity-modulated radiotherapy decreases the risk of moist desquamation. The development of the gating offers greater protection of certain critical organs including lung, heart, and chest/ribs. ...
Cavum Septi Pellucidi in Boxers
2010-01-01
AbregeObjectif Il existe une controverse au sujet de limportance de la decouverte isolee dun cavum septum pellucidum (CSP) et de son taux de prevalence chez les personnes en bonne sante et chez les boxeurs professionnels. Peu detudes dimagerie par resonance magnetique (IRM) se sont penchees sur dimportantes cohortes de boxeurs. Cette etude avait pour but de determiner la prevalence et letendue des CSP chez les boxeurs professionnels et de les comparer avec celles dun groupe temoin. Methodes Les etudes dIRM de 164 boxeurs, tous des hommes, realisees aux fins du renouvellement annuel de leur permis de boxe en Grande-Bretagne ont ete examinees, puis comparees avec celles de 43 patients dun groupe temoin. La prevalence, la taille et letendue des CSP ont ete consignees. Letendue etait classee c...
Amliorer la sensibilit la leptine vers un remde contre lobsit
2008-01-01
Rsum Produite par le tissu adipeux, la leptine rgule positivement le comportement alimentaire et la dpense nergtique. Cependant, les personnes obses, chez qui le taux de leptine est anormalement lev, sont incapables de rpondre lhormone et se trouvent dans un tat de rsistance. La leptine dclenche la rponse biologique en activant ses rcepteurs (OB-R), et leur quantit expose la surface de la cellule est un des facteurs dterminants de la sensibilit dune cellule la leptine. Notre quipe a identifi OB-RGRP, qui est issu du mme gne que celui codant pour OB-R, comme un nouveau rgulateur de ce dernier. OB-RGRP est une protine quatre domaines transmembranaires qui interagit avec OB-R et le retient dans les compartiments intracellulaire...
1982-01-01
A comparison was made of the direct transfer of cesium from water to carps and the indirect transfer via the food. In a first experiment on chronic contamination of carps by water, the kinetics and distribution of cesium in the organs of the carps were studied. Equilibrium was not reached on the 56th day, 4% of the initial water activity had been retained by the carps and the concentration factor was below 10. The highest specific activities were found in the transit organs. In a second experiment, the water activity varied by alternating contamination and decontamination. A fluctuating equilibrium was reached on the 22nd day. The concentration factor was of the same order of magnitude than in the previous experiment. Indirect contamination of fish by ingestion of contaminated daphnids was studied in a third experiment. Cesium levels in carps increased with the cumulated ...
1972-07-01
An important feature in radiological safety studies of sites is the knowledge of water movements in the unsaturated layer surmounting aquifer; this zone of aerated soil can be effective as a protection against aquifer contamination. Utilizing a neutron-moisture meter, a method was developed permitting to build graphically the hydric states of soil and the moistened volume evolution with time in the particular case of a limited feeding surface. It is also possible to measure moisture gradients, drying kinetics, the retention capacity of soil and the gravific water content achieved by a given water head. The initial hydric state has an effect only upon the infiltration rate and neither upon the moistened front position nor upon the volume of moistened soil; consequently, the storable water amount in soil can be calculated. When water feeding has been stopped, the volume of moistened soil increases to an equilibrium state restricted by the moistened front and all the other water movements occur exclusively inside this volume. Consequently in case of radioactive waste disposal, the ionic pollution will be confined inside a measurable volume, the moistened front being the maximum limits of this volume. Part 2. Following up the report on water movements in non-saturated s o i l s after reject on a limited space - CEA R 3635 (1) - the radioactive ions movements in these soils are studied in using an anion and a cation of reference: iodine 131 and strontium 85. The experimental method is founded on the simultaneous measurements of moisture and radioactivity fronts by means of a neutrons moisture meter and an specially conceived radioactivity probe. It has so been possible to measure: the relative velocities of moisture and radioactivity fronts; the contaminated soil volume inside the moistened oil volume; the concentration gradients; the contamination changes upon watering; the effect of chemical composition of water upon this ions movements and the effect of soil moisture upon the counting rate of radioactivity. This method which have allowed to get various results about {sup 131}I and {sup 85}Sr can be generalized to other radioisotopes and other soils. They are applicable to radiological safety of sites studies : Testing storage plants, estimate of accidents hazards and protection of subterranean waters. (author) [French] II est important, dans les etudes de surete radiologique de sites, de connaitre les mouvements d'eau dans les terrains non satures surmontant la nappe aquifere, cette tranche de terrain aere pouvant servir de protection contre la contamination de la nappe. L'utilisation d'humidimetres a neutrons a permis de construire graphiquement les coupes des etats hydriques du terrain et les evolutions dans le temps du volume du sol mouille a partir d'un rejet affectant une superficie restreinte. On mesure aussi les gradients d'humidite, les cinetiques d'assechement, la capacite de retention du sol et la teneur en eau gravifique suspendue en en equilibre avec la charge d'eau. L'etat hydrique initial influence la vitesse d'infiltration et non la vitesse d'avancement du front d'humectation, on peut donc calculer la quantite d'eau accumulable par le terrain. Apres l'arret du rejet, le volume de sol mouille evolue jusqu'a un etat d'equilibre limite par le front d'humectation, les redistributions d'humidite s'effectuant seulement au sein de ce volume; ainsi, en cas de rejet de liquide radioactif, les ions contaminants resteront confines dans un volume mesurable limite par le front d'humectation. Partie 2. Pour faire suite au rapport sur les mouvements d'eau dans les sols non satures apres rejet sur une surface limitee - CEA R 3635 (1) - on etudie les mouvements des ions radioactifs dans ces sols en utilisant un anion et un cathion caracteristiques: l'iode 131 et le strontium 85. La methode est basee sur la mesure simultanee des fronts d'humidite et d'activite au moyen d'humidimetre a neutrons et d'une sonde d'activite specialement concue. On a pu ainsi mesurer: les vitesses relatives des fronts d'humidite et d'activite; le volume de sol contamine a l'interieur du volume de sol mouille; les gradients de concentration; l'evolution de la contamination sous l'effet de lessivages; l'influence de la composition chimique de l'eau sur la migration des ions et l'influence de l'humidite du sol sur le taux de comptage de la radioactivite. Ces methodes qui ont ete mises au point avec l'iode 131 et le strontium 85 peuvent etre utilisees avec d'autres radioelements et appliquee aux etudes de surete radiologiques des sites: controle d'installations de stockage, evaluation des risques ou des consequences d'accidents et protection des nappes aquiferes. (auteur)
1967-07-01
Three parts of the report treat the questions related to the tandem, the cyclotrons and the electrons linear accelerators, then two annexes give the role of publications in this year, and the list of scientific and technical personnel. In the area of Van de Graaff and cyclotrons, progress has been made in the realisation of particles identification systems and in the methods of data processing. The starting up of the trochoidal injection has allowed an improvement of the protons polarisation rate and the intensity increase by a factor 1000. [French] Trois parties traitent des questions concernant le tandem, les cyclotrons et les accelerateurs lineaires a electrons, puis deux annexes donnent la liste des publications de l'annee et la liste du personnel scientifique et technique. Dans le domaine des Van de Graaf et cyclotrons, il faut signaler les progres dans la realisation de systemes d identification de particules et dans les methodes de traitement de donnees. La mise en service de l injection trochoidale a permis une amelioration du taux de polarisation des protons et l'accroissement de l'intensite d un facteur 1000. (auteurs)
1964-12-01
For these measures, the information used is the light polarization plane rotation induced by the magnetic field in a glass probe. This rotation is detected using a polarizer-analyzer couple. The detector is a photomultiplier used with high-current and pulsed light. In a distributed magnet (gap: 6 x 3 x 3 cm) magnetic fields to measure are 300 gauss, lasting 0.1 {mu}s, with rise times {<=} 35 ns, repetition rate: 1/s. An oscilloscope is used to view the magnetic field from the P.M. plate signal. The value of the field is computed from a previous static calibration. Magnetic fields from 50 to 2000 gauss (with the probe now used) can be measured to about 20 gauss {+-} 5 per cent, with a frequency range of 30 MHz. (author) [French] Pour faire de telles mesures, on utilise comme information la rotation du plan de polarisation de la lumiere provoquee par le champ magnetique dans une sonde en verre. On detecte cette rotation au moyen d'un polariseur et d'un analyseur, qui sont regles a 45 deg. pour conserver un phenomene lineaire. Le detecteur est un photomultiplicateur travaillant en fort courant en lumiere pulsee. Dans un aimant distribue d'entrefer 6 x 3 x 3 cm, on obtient des champs magnetiques a mesurer de 300 gauss, durant 0.1 {mu}s, avec des temps de montee {<=} 35 ns; au taux de 1 fois par seconde. L'observation du champ se fait sur oscilloscope a partir du signal de plaque du P.M. La valeur absolue du champ est obtenue au moyen d'un etalonnage statique prealable. On peut ainsi mesurer a 20 gauss et {+-} 5 pour cent pres environ des champs magnetiques de 50 a 2000 gauss (avec la sonde actuelle) et avec une bande passante de 30 MHz. (auteur)
Evaluation of the French Haut Taux de Combustion (HTC) Critical Experiment Data
In the 1980s, a series of critical experiments referred to as the Haut Taux de Combustion (HTC) experiments was conducted by the Institut de Radioprotection et de Surete Nucleaire (IRSN) at the experimental criticality facility in Valduc, France. The plutonium-to- uranium ratio and the isotopic compositions of both the uranium and plutonium used in the simulated fuel rods were designed to be similar to what would be found in a typical pressurized-water reactor fuel assembly that initially had an enrichment of 4.5 wt% {sup 235}U and was burned to 37,500 MWd/MTU. The fuel material also includes {sup 241}Am, which is present due to the decay of {sup 241}Pu. The HTC experiments include configurations designed to simulate fuel handling activities, pool storage, and transport in casks constructed of thick lead or steel. Rights of use for the HTC experiment data were purchased under an agreement that limits release of the information. Consequently, a detailed and complete description of the experiments is not presented in this report. This report discusses evaluation of the four HTC data reports, modeling of the experiments, sensitivity and uncertainty analysis, and upper subcritical limit (USL) calculation. The report also presents some conclusions and recommendations concerning use of the HTC experiment data for burnup credit applications. The similarity of the HTC experiments with PWR spent nuclear fuel has been quantified using sensitivity/uncertainty analysis, confirming that the HTC experiments are significantly more applicable to the validation of burnup credit calculations than other available mixed-oxide (MOX) experiments. The HTC experiments were designed and executed with a high level of rigor, resulting in experimental uncertainties that are lower than many of the earlier MOX experiments. The HTC data reports, together with information provided in this report, provide sufficient data to allow for either detailed or simplified computational models to be developed. The HTC experiments substantially strengthen the technical basis for validation by adding to the previously small number of applicable experiments against which to compare burnup credit applications. Existing MOX experiments found to be applicable are also identified in this report.
Evaluation of the French Haut Taux de Combustion (HTC) Critical Experiment Data
In the 1980s, a series of critical experiments referred to as the Haut Taux de Combustion (HTC) experiments was conducted by the Institut de Radioprotection et de Surete Nucleaire (IRSN) at the experimental criticality facility in Valduc, France. The plutonium-to- uranium ratio and the isotopic compositions of both the uranium and plutonium used in the simulated fuel rods were designed to be similar to what would be found in a typical pressurized-water reactor fuel assembly that initially had an enrichment of 4.5 wt% {sup 235}U and was burned to 37,500 MWd/MTU. The fuel material also includes {sup 241}Am, which is present due to the decay of {sup 241}Pu. The HTC experiments include configurations designed to simulate fuel handling activities, pool storage, and transport in casks constructed of thick lead or steel. Rights of use for the HTC experiment data were purchased under an agreement that limits release of the information. Consequently, a detailed and complete description of the experiments is not presented in this report. This report discusses evaluation of the four HTC data reports, modeling of the experiments, sensitivity and uncertainty analysis, and upper subcritical limit (USL) calculation. The report also presents some conclusions and recommendations concerning use of the HTC experiment data for burnup credit applications. The similarity of the HTC experiments with PWR spent nuclear fuel has been quantified using sensitivity/uncertainty analysis, confirming that the HTC experiments are significantly more applicable to the validation of burnup credit calculations than other available mixed-oxide (MOX) experiments. The HTC experiments were designed and executed with a high level of rigor, resulting in experimental uncertainties that are lower than many of the earlier MOX experiments. The HTC data reports, together with information provided in this report, provide sufficient data to allow for either detailed or simplified computational models to be developed. The HTC experiments substantially strengthen the technical basis for validation by adding to the previously small number of applicable experiments against which to compare burnup credit applications. Existing MOX experiments found to be applicable are also identified in this report.
Evaluation of the French Haut Taux de Combustion (HTC) Critical Experiment Data
2008-09-01
In the 1980s, a series of critical experiments referred to as the Haut Taux de Combustion (HTC) experiments was conducted by the Institut de Radioprotection et de Surete Nucleaire (IRSN) at the experimental criticality facility in Valduc, France. The plutonium-to- uranium ratio and the isotopic compositions of both the uranium and plutonium used in the simulated fuel rods were designed to be similar to what would be found in a typical pressurized-water reactor fuel assembly that initially had an enrichment of 4.5 wt% {sup 235}U and was burned to 37,500 MWd/MTU. The fuel material also includes {sup 241}Am, which is present due to the decay of {sup 241}Pu. The HTC experiments include configurations designed to simulate fuel handling activities, pool storage, and transport in casks constructed of thick lead or steel. Rights of use for the HTC experiment data were purchased under an agreement that limits release of the information. Consequently, a detailed and complete description of the experiments is not presented in this report. This report discusses evaluation of the four HTC data reports, modeling of the experiments, sensitivity and uncertainty analysis, and upper subcritical limit (USL) calculation. The report also presents some conclusions and recommendations concerning use of the HTC experiment data for burnup credit applications. The similarity of the HTC experiments with PWR spent nuclear fuel has been quantified using sensitivity/uncertainty analysis, confirming that the HTC experiments are significantly more applicable to the validation of burnup credit calculations than other available mixed-oxide (MOX) experiments. The HTC experiments were designed and executed with a high level of rigor, resulting in experimental uncertainties that are lower than many of the earlier MOX experiments. The HTC data reports, together with information provided in this report, provide sufficient data to allow for either detailed or simplified computational models to be developed. The HTC experiments substantially strengthen the technical basis for validation by adding to the previously small number of applicable experiments against which to compare burnup credit applications. Existing MOX experiments found to be applicable are also identified in this report.
Radiological Risk Assessment of Capstone Depleted Uranium Aerosols
2009-01-01
Assessment of the health risk from exposure to aerosols of depleted uranium (DU) is an important outcome of the Capstone aerosol studies that established exposure ranges to personnel in armored combat vehicles perforated by DU munitions. Although the radiation exposure from DU is low, there is concern that DU deposited in the body may increase cancer rates. Radiation doses to various organs of the body resulting from the inhalation of DU aerosols measured in the Capstone studies were calculated using International Commission on Radiological Protection (ICRP) models. Organs and tissues with the highest calculated committed equivalent 50-yr doses were lung and extrathoracic tissues (nose and nasal passages, pharynx, larynx, mouth and thoracic lymph nodes). Doses to the bone surface and kidney were about 5 to 10% of the doses to the extrathoracic tissues. The methodologies of ...
1969-07-01
A comparative study of both the evolution of strontium-90 content in the bones of individuals of different ages for the period 1962-1967 as related to calcium, and the corresponding diets allowed to establish the relationship between food contribution and the resulting bone burden. The study is mainly devoted to the group of adults for which a mathematical expression is proposed which allows for the exchangeable form of a skeletal calcium fraction turned over in less than a year from the dietary calcium, and the stabilized form constituting the larger part of bone tissue characterized by a slow turnover. Both the amount of the exchangeable fraction and the turnover rate of the stabilized fraction are determined for vertebrae and ribs. At birth, bone levels indicate that the calcium used for skeleton modelling during foetal life originates from both maternal diet and bone tissue and a value is given, to their relative significance. There appears a good relationship between bone levels in infants from 6 months to 1 year of age and their diets. The physiological parameters particular to this age are quantified. (authors. [French] L'etude comparee de l'evolution de la teneur en strontium 90 rapportee au calcium, mesuree dans les os d'individus a differents ages durant la periode 1962-1967 et celle du regime alimentaire correspondant, a permis d'etablir la relation qui existe entre l'apport du a l'alimentation et la charge osseuse qui en resulte. L'essentiel de l'etude est consacre au cas des adultes. Pour ce groupe la formulation mathematique proposee tient compte de la presence de la forme echangeable d'une fraction du calcium osseux, renouvelee en moins d'un an a partir du calcium alimentaire, et de la forme stabilisee, constituant la majeure partie du tissu osseux, caracterisee par un renouvellement lent. L'importance de la fraction echangeable, ainsi que le taux de renouvellement de la fraction stabilisee sont etablis pour les vertebres et les cotes. La contamination des os a la naissance montre que le calcium utilise durant la vie foetale pour la formation du squelette provient a la fois de l'alimentation et du tissu osseux maternel. L'importance relative des deux origines est chiffree. Une bonne correlation apparait entre la contamination des os des enfants ages de 6 mois a 1 an et celle de leur alimentation. Les parametres physiologiques particuliers a cet age sont quantifies. (auteurs)
1969-07-01
The measurement of electromagnetic radiations is difficult in the energy range 20-100 keV. We made suitable for this purpose a regular proportional counter, modifying both the nature and pressure of the gaseous mixture filling the detector volume. We selected the CPEN-SAIP counter, which is able to withstand such modifications. In the energy range considered, the counter is to be standardized with radioactive sources. Such standards were selected according to their disintegration schemes. We thus defined the conditions of use (resolution, yield) of the CPN counter, filled with an argon-methane mixture under a pressure of about 3 bars, in the energy range 5-100 keV. With such an equipment, we were able to measure the absolute disintegration rate for the X-rays of 133 Ba and 75 Se, then to perform the study of a mixed fission products sample. In the same way, we used xenon-based gaseous mixtures, in order to improve the detector yield; in the later case, we carefully examined the limitations introduced by the presence of many parasite rays emitted by the gas. We thus displayed in addition to the leakage peak, the fluorescence ray of the gas, whose origin is difficult to explain. (author) [French] La mesure des rayonnements electromagnetiques est difficile dans une bande d'energie comprise entre 20 et 100 keV environ. Nous avons rendu utilisable, a cet effet, un compteur proportionnel existant en modifiant la nature et la pression du melange gazeux constituant le volume detecteur. De par sa construction, le compteur CPXN, fabrique par les Etablissements S.A.I.P., rend ces experiences possibles. C'est pourquoi nous l'avons choisi. Dans le domaine d'energie consideree l'etalonnage du compteur necessite l'emploi de sources radioactives. Pour les preparer, nous sommes amenes a choisir les radio-nucleides utilisables par l'etude de leur schema de desintegration. Ainsi, nous avons defini les conditions d'utilisation (resolution, efficacite) du compteur CPNX rempli d'un melange d'argon et de methane a la pression de trois atmospheres environ dans un domaine d'energie de 5 100 kev. Utilise dans ces conditions, ce compteur nous a permis de mesurer le taux d'emission absolu de rayonnements X du {sup 133}Ba et du {sup 75}Se, et de proceder a l'etude d'un echantillon de produits de fission. De meme, nous avons egalement utilise des melanges gazeux a base de xenon, afin d'augmenter le rendement du detecteur; dans ce dernier cas, nous avons particulierement examine les limitations introduites par la presence de nombreuses raies parasites issues du gaz. C'est ainsi que nous avons mis en evidence, outre les pics d'echappement, la raie de fluorescence du gaz dont l'origine est difficilement explicable. (auteur)
2007-07-01
This study deals with the GMAW process evaluation for the orbital butt welding of strong thickness pipings, in order to increase the productivity of these operations (higher deposition rate than in GTAW, process currently used). The main goal of this project is to evaluate the operational feasibility of mechanized orbital welding under gas protection in narrow gap with stainless flux cored wire 308L on stainless steel 304L. The study was composed of two parts with firstly a bibliographical research which has allowed to underline this operation practice, as good with rutile flux cored wire in smooth mode as with metal cored wire in pulsed mode. In the second part, flat and in position welding tests, by unit cords and filling of narrow grooves, made possible to define preliminary welding parameters. (author) [French] Cette etude s'inscrit dans le cadre de l'evaluation du procede MIG/MAG pour le soudage orbital bout a bout de tuyauteries de forte epaisseur, afin d'augmenter la productivite de ces operations (taux de depot plus eleve qu'en TIG, procede utilise actuellement). L'objectif du projet est d'evaluer la faisabilite operatoire du soudage orbital sous protection gazeuse en chanfrein etroit en mode mecanise avec fil fourre inoxydable 308L sur acier inoxydable 304L. L'etude s'est deroulee en deux parties avec dans un premier temps une recherche bibliographique qui a permis de mettre en evidence la pratique de cette operation, aussi bien avec des fils fourres rutiles en regime lisse qu'avec des fils fourres a poudre metallique en regime pulse. Dans un second temps, des essais de soudage a plat et en position, en cordons unitaires et en remplissage de chanfreins etroits, ont permis de definir des parametres preliminaires de soudage. (auteur)
1958-07-01
A system is described for measuring the mean absorption cross section in thermal neutrons of graphite. This system consists of a graphite stack containing a Ra-Be source and a BF3 counter. A cavity in the stack receives the graphite to be studied or the graphite standard. By comparing the counting rates their absorption ratio can be deduced. The measurement is performed on graphite rods which have been machined before being placed in the pile. It provides the possibility of detecting over a batch of 1 ton of graphite, in a single measurement, a difference in absorption of 0.1 milli barn. (author) [French] On decrit un dispositif permettant de mesurer la section efficace moyenne d'absorption en neutrons thermiques du graphite. Ce dispositif est constitue par un empilement de graphite contenant une source de Ra-Be et un compteur a BF3. Une cavite menagee dans l'empilement peut recevoir le graphite a etudier ou le graphite etalon. Par comparaison des taux de comptage, on en deduit leur rapport d'absorption. La mesure est effectuee sur des barres de graphite usinees avant leur mise en place dans la pile. Elle permet de deceler sur un lot de graphite de 1 tonne, en une seule mesure, une difference d'absorption de 0,1 millibarn. (auteur)
Parametric analysis of loop heat pipe operation: a literature review
2007-07-15
Loop heat pipes (LHPs) are heat transfer devices whose operating principle is based on the evaporation/condensation of a working fluid, and which use the capillary pumping forces to ensure the fluid circulation. Their major advantages as compared to heat pipes are an ability to operate against gravity and a greater maximum heat transport capability. In this paper, a literature review is carried out in order to investigate how various parameters affect the LHP operational characteristics. This review is based on the most recent published experimental and theoretical studies. After a reminder of the LHP operating principle and thermodynamic cycle, their operating limits are described. The LHP thermal resistance and maximum heat transfer capability are affected by the choice of the working fluid, the fill charge ratio, the porous wick geometry and thermal properties, the sink and ambient temperature levels, the design of the evaporator and compensation chamber, the elevation and tilt, the presence of non-condensable gases, the pressure drops of the fluid along the loop. The overall objective for this paper is to point the state-of-the-art for the related technology for future design and applications, where the constraints related to the LHPs are detailed and discussed. (author) [French] Les boucles diphasiques a pompage capillaire sont des systemes dont le principe de fonctionnement est base sur l'evaporation/condensation d'un fluide et qui utilisent les forces de capillarite pour faire circuler le fluide dans la boucle. En comparaison des caloducs, les principaux avantages des boucles diphasiques a pompage capillaire sont une aptitude a vaincre les forces de gravite, lorsque le systeme est en position defavorable, et une puissance maximale transferable superieure. La presente etude bibliographique, basee sur les travaux experimentaux et theoriques les plus recents, a pour but est de comprendre comment differents parametres influencent le comportement de la boucle. Apres un rappel du principe de fonctionnement et du cycle thermodynamique de la pompe, ses limites de fonctionnement sont decrites. Sa resistance thermique et sa puissance maximale transferable dependent du choix du fluide de travail, du taux de remplissage, de la geometrie et des proprietes thermophysiques de la structure capillaire, de la temperature ambiante, de la temperature de la source froide, de la geometrie de l'evaporateur et de la chambre de compensation, de l'elevation et l'inclinaison du systeme, de la presence de gaz incondensables et des pertes de pression du fluide le long de la boucle. L'objectif de cet article est de presenter l'etat de l'art relatif aux influences de divers parametres sur le fonctionnement des LHPs. (orig.)
1965-06-01
A study of the changes in the lead-210 contents of rain-water and of water produced by melting polar ice has required the development of a method for dosing lead-210, an {alpha} emitter. This method is 40 times more sensitive than that which measures the lead-210 by bismuth-210, a ({beta} emitter. The first part of the report presents the study of a spectrometry using semiconductor detectors; a catalogue of a spectra shows the advantages of this method. In the second part will be found at first a new chemical separation method for polonium-210 and the results obtained with this method. The main results obtained on the geophysical behaviour of lead-210 are the following: - the monthly lead-210 and polonium-210 contents in rain water are approximately constant with time. - in the Gif-sur-Yvette region, the clean-up by 'dry fall-out' can attain 40 to 50 per cent of the total fall-out. - a study of Antarctic ice samples makes it possible to determine an annual accumulation rate equivalent to 13.8 cm of water and to show discrepancies in the periodic concentrations which correspond to the latest maxima of solar activity. - a balance is drawn up between the radon produced by the continents and the lead-210 fall-out. (author) [French] Une etude sur les variations de la teneur en plomb 210 des eaux de pluie et des eaux de fusion des glaces polaires a necessite la mise au point d'une methode de dosage du plomb 210 emetteur {alpha}. Cette methode permet d'obtenir une sensibilite quarante fois superieure a celle dosant le plomb 210 par le bismuth 210 emetteur {beta}. La premiere partie du travail presente l'etude de la spectrometrie {alpha} par detecteur a semiconducteurs, un catalogue de spectres {alpha} met en evidence les avantages de cette methode. Dans la deuxieme partie on trouvera en premier lieu une nouvelle methode chimique de separation du polonium 210 ainsi que les resultats obtenus grace a cette methode. Les principaux resultats sur le comportement geophysique du plomb 210 sont les suivants: - la teneur mensuelle en plomb 210 et en polonium 210 dans les eaux de pluie est a peu pres constante en fonction du temps. - dans la region de Gif-sur-Yvette, le nettoyage par 'retombee seche' peut atteindre 40 a 50 pour cent de la retombee totale. - une etude sur des carottes de glace de l'Antarctique permet de determiner un taux annuel d'accumulation equivalent a 13.8 cm d'eau et de mettre en evidence des anomalies de concentration periodiques en concordance avec les derniers maximums d'activite solaire. - un bilan est etabli entre le degagement de radon des continents et les retombees de plomb 210. (auteur)
1964-06-01
We have studied, in various culture media, how the absorption of caesium by barley varies with its concentration, and how this absorption can be in competition with a similar alkali cation-potassium. We have also considered the caesium distribution in the ground in particular radio-active caesium, between the soil and solution, as a function of the amount of caesium. From our work it is clear that barley behaves very differently according to whether the caesium is in a nutritive solution or is in the soil: for a nutritive solution, the fraction of caesium (radioactive and stable) absorbed by barley remains practically constant in the presence of increasing amounts (relatively small) of stable caesium; in soil, the fraction of the radio-active caesium absorbed increases as the stable caesium content (fairly low) of the soil increases, in relationship with a rapidly decreasing selectivity of the soil for Cs{sup +}. The difference between these results is thus explained by the very pronounced selectivity of the illitic soil studied for Cs{sup +}, as long as the proportion of Cs remains low, about as low as that of most natural soils. Furthermore, the K{sup +} ion is in competition with the Cs{sup +} ion, for absorption by barley in a culture medium in a nutritive solution or in soil, only when the potassium concentrations are relatively low, of the order of the nutritive maximum. This shows that the addition of potassium to a medium already rich in this element does not reduce the absorption of caesium by barley. The choice of experimental conditions close to natural conditions (nutritive media strong in calcium) and the examination of the distribution of radioactive caesium between the soil, the soil solution and the plant in the presence of very low doses of stable caesium make these results interesting from the 'atomic health' point of view; it should be expected that a definite contamination risk exists for plants cultivated on synthetic media and for plants such as rice and cress growing on flooded soils. Radio-active caesium however incorporated without carrier into a soil of medium-exchange capacity (of about 150 milli-equivalents per kilo) presents relatively little danger because of the close interdependence of the radioactive caesium take-up from the soil by the plants and its retention by the soil. Our research has made it possible furthermore to examine the value of various partial decontamination methods for soils proposed by certain atomic scientists: just as isotopic dilution appears totally inadequate for this purpose, so does it seems that the addition of potassium salts in amounts greater than nutritive optimum is incapable of reducing the absorption of radioactive caesium by the plant. (author) [French] Nous avons recherche, dans divers milieux de culture, comment l'absorption du cesium par l'orge varie avec sa concentration et comment cette absorption peut etre concurrencee par un cation alcalin voisin,le potassium. En outre, nous avons considere la distribution du cesium dans le sol - notamment du cesium radioactif - entre terre et solution, en fonction du taux de cesium. De notre etude ressort une nette opposition entre le comportement de l'orge vis a vis du cesium d'une solution nutritive et vis a vis du cesium d'un sol: sur solution nutritive, la fraction du cesium (radioactif et stable) absorbee par l'orge demeure pratiquement constante en presence de proportions croissantes (relativement petites) de cesium stable; sur sol, la fraction du cesium radioactif absorbee par l'orge a augmente en meme temps que le taux (relativement petit) de cesium stable du sol, en relation avec une selectivite rapidement decroissante du sol pour Cs. La difference entre ces resultats est donc expliquee par une tres forte selectivite du sol illitique experimente pour Cs{sup +} tant que la proportion da cesium reste tres petite, de l'ordre de celle de la plupart des sols naturels. Par ailleurs, l'ion K{sup +} n'a concurrence l'absorption de Cs{sup +} par l'orge en milieux de culture sur solution nutritive et sur sol, que jusqu'a des doses relativement faibles de potassium, de l'ordre de l'optimum nutritif. Ceci montre que l'addition de potassium a un milieu deja riche en cet element ne reduit plus l'absorption de cesium par l'orge. Le choix de conditions experimentales proches des conditions naturelles (milieux nutritifs a dominante de calcium) et l'examen de la distribution du cesium radioactif entre sol, solution du sol et plante en presence de tres petites doses de cesium stable, conferent a ces resultats un interet 'hygiene atomique': on doit s'attendre a un risque de contamination certain pour les vegetaux cultives sur milieux synthetiques et pour les vegetaux croissant sur des sols inondes tels que le riz et le cresson. Mais le cesium radioactif incorpore sans entraineur a un sol de capacite d'echange moyenne (de l'ordre de 150 milliequivalents par kg) presente relativement peu de danger, du fait de la dependance etroite entre le prelevement de Cs radioactif du sol par les plantes et sa retention dans le sol. Nos experiences nous ont permis en outre d'examiner la valeur des moyens de decontamination partielle d'un sol proposes par certains atomistes: de meme que la dilution isotopique se revele totalement inefficace sous cet angle, l'apport de sels de potasse en quantite depassant l'optimum nutritif se revele incapable de reduire l'absorption de cesium radioactif par la plante.
Applications of Capstone Depleted Uranium Aerosol Risk Data to Military Combat Risk Management
2009-01-01
Risks to personnel engaged in military operations include not only the threat of enemy firepower but also risks from exposure to other hazards such as radiation. Combatant commanders of the U. S. Army carefully weigh risks of casualties before implementing battlefield actions using an established paradigm that take these risks into consideration. As a result of the inclusion of depleted uranium (DU) anti-armor ammunition in the conventional (non-nuclear) weapons arsenal, the potential for exposure to DU aerosols and its associated chemical and radiological effects becomes an element of the commanders risk assessment. The Capstone DU Aerosol Study measured the range of likely DU oxide aerosol concentrations created inside a combat vehicle perforated with a DU munition, and the Capstone Human Health Risk Assessment (HHRA) estimated the associated doses and calculated ...
Defect of a Kronecker product of unitary matrices
2010-09-22
The defect d(U) of an NxN unitary matrix U with no zero entries is the dimension (called the generalized defect D(U)) of the real space of directions, moving into which from U we do not disturb the moduli |U_ij| as well as the Gram matrix U'*U in the first order, diminished by 2N-1. Calculation of d(U) involves calculating the dimension of the space in R^(N^2) spanned by a certain set of vectors associated with U. We split this space into a direct sum, assuming that U is a Kronecker product of unitary matrices, thus making it easier to perform calculations numerically. Basing on this, we give a lower bound on D(U) (equivalently d(U)), supposing it is achieved for most unitaries with a fixed Kronecker product structure. Also supermultiplicativity of D(U) with respect to Kronecker subproducts of U is shown.
2000-07-01
This paper presents fundamental researches based on the electronic structure calculations and X absorption spectroscopy, allowing the knowledge on nuclear fuels at an atomic scale. They bring a better understanding of these material behavior to accurate the macroscopic simulation. The calculation methods, the experimental techniques of validation and the ab initio calculations results are detailed. (A.L.B.)
1967-07-01
Apparent contradictions in the properties of pyrolytic carbons obtained at 1600 deg C (hardness and graphitization) are studied. It is shown that structure of the deposit is turbostratic with high internal stresses ({delta}{sup -2}), and it graphitizes (by thermal treatment over 2000 deg C) in a similar manner to graphitisable carbon. Because the deposit forms lamellar compounds, it is presumed that the structure is similar to that of graphitisable carbon. Since it is not structure dependant, the hardness originates from the 'growth texture' and is not comparable with the hardness of a non-graphitisable carbon. The pyrolytic carbon studied is composed of regions, on the overage a few microns across, formed by the stacking of small carbon platelets, interlocked and showing a preferred orientation. The mis-orientation of the various regions produces general disorientation. We estimate that the introduction of the particles of some material such as thermal black which are observed in the electron microscope are responsible for the mis-orientation. The density and hardness of the deposit are a result of the interlocking of platelets, which creates a closed porosity and prevents any sliding of the atomic planes. (author) [French] On etudie les proprietes apparemment contradictoires du pyrocarbone 1600 deg C, durete et graphitabilite. On montre que le pyrocarbone possede la structure d'un carbone turbostratique a fort taux de distorsion et qu'il subit, par traitement a des temperatures superieures a 2000 deg C, une transformation de graphitation comparable a celle que l'on observe sur les cokes graphitables. Comme le pyrocarbone forme de plus des composes d'insertion, sa structure est comparable a celle d'un carbone graphitable. La durete, qui n'a pas d'origine structurale, est donc liee a la 'texture de croissance' du depot et ne peut etre comparee a celle d'un coke dur et non graphitable. Le pyrocarbone etudie est constitue de domaines, dont les dimensions sont de l'ordre de quelques microns, formes par un empilement de lamelles de carbone de faible dimension, enchevetrees les unes dans les autres et presentant entre elles une orientation preferentielle. C'est la diversite d'orientation des domaines qui determine la desorientation generale du depot. Nous pensons qu'elle est provoquee par l'introduction de particules, peu differentes d'un noir thermique, dont la presence a ete mise en evidence a l'aide du microscope electronique. La densite et la durete du depot sont liees a l'enchevetrement des lamelles, enchevetrement qui cree une porosite fermee et un blocage du glissement des couches atomiques. (auteur)
Caractrisation physique et mcanique de l'acier 4140 nitrur et implant
La nitruration est un procd thermochimique destin amliorer les proprits chimiques et mcaniques des aciers et des fontes. Les procds les plus courant sont la nitruration gazeuse, la nitruration en bain de sels et la nitruration ionique par plasma. Cette dernire prsente certains avantages par rapport aux deux prcdentes, elle est moins polluante, consomme moins d'nergie et permet un traitement local. De manire gnrale, quel que soit le procd utilis, le processus de nitruration des aciers se caractrise par la diffusion d'azote partir de la surface vers le c?ur du matriau et par la formation d'une couche de combinaison superficielle aprs une priode d'incubation. Si le temps du traitement est suffisamment long, on constate un ralentissement de la croissance de la couche de combinaison alors que la diffusion de l'azote se poursuivre vers le c?ur de la pice en formant une solution solide d'insertion dans la nitroferrite ou des prcipits de nitrures ou de carbonitrures d'lments allis. Pour ce travail et en vue d'amliorer le comportement mcanique des chantillons, les aciers nitrurs ioniquement pour deux taux d'activation ont subi un traitement supplmentaire d'implantation d'ions d'azote. La caractrisation, tant du point de vue microstructurale que mcanique, des couches obtenues partir de la nitruration ionique avec ou sans implantation ionique a t effectu et les moyens utiliss dans cette tude sont la microduret, diffraction de rayons X, microscopies optique et lectronique balayage.
1968-03-01
A spectrophotometric determination was made of the complexes of cerium and uranides in their different degrees of oxidation with diethylenetriaminepentaacetic acid (DTPA). Two physico-chemical states, the ionic and hydrolysis ones, were considered. In the former case, we studied the influence of the pH on the formation of the complex, and whenever the complexes were stable, we determined the molecular ratio and calculated their stability constants. In the latter case, we studied the conditions of solubilization of the precipitate by formation of complexes soluble in water as a function of pH, age of the precipitate and time of precipitate-chelate contact. (authors) [French] Etude spectrophotometrique de la complexation du cerium et des uranides (uranium, neptunium, plutonium et americium) dans leurs differents etats d'oxydation par l'acide diethylenetriaminepentaacetique (DTPA). Deux etats physicochimiques ont retenu notre attention, l'etat ionique et l'etat precipite d'hydrolyse. Dans le premier cas, nous avons etudie l'influence du pH sur la formation du complexe, et dans tous les cas ou le complexe est stable, nous avons determine le rapport moleculaire (5) [element]/[chelatant] du complexe forme et nous avons calcule leurs constantes de stabilite. Dans le deuxieme cas, l'etat de precipite d'hydrolyse, nous avons etudie les conditions de solubilisation du precipite, par formation du complexe, en fonction du pH, de l'age du precipite et du temps de contact precipite - chelatant. (auteurs)
1964-07-01
The apparatus which has been developed is designed to give the reciprocal of a number between 10{sup 3} and 10{sup 7}. In practice this number can be the pulse count provided during a given time by a detector of the BF{sub 3} type during a criticality experiment. The apparatus is made up of two parts: one provides, by means of relays, a voltage proportional to the reciprocal required, the other is a numeric voltmeter measuring this voltage between 0.1 and 1 volt. The relative error of the result is under 5 per cent. (author) [French] L'appareillage etudie et realise, est destine a fournir l'inverse d'un nombre compris entre 10{sup 3} et 10{sup 7}. En pratique ce nombre est le taux d'impulsions delivrees pendant un temps donne, par un detecteur du type BF{sub 3}, au cours d'une manipulation de criticalite. L'appareillage est compose de deux parties: l'une fournit a l'aide de relais une tension proportionnelle a l'inverse cherche, l'autre est un voltmetre numerique mesurant cette tension comprise entre 0,1 et 1 Volt, L'erreur relative sur le resultat est inferieure a 5%. (auteur)
2009-01-01
Introduction De par sa capacite a reguler le stockage des acides gras et a secreter des cytokines pro-inflammatoires, l'adipocyte apparait comme une cellule-cle dans la regulation energetique et immunitaire. L'IL-7, surtout connue pour ses fonctions immunes (Calzascia PNAS 08, Harnaha Diabetes 06) semble participer egalement a la formation de la masse grasse. Les dysregulations du tissu adipeux sont nombreuses : obesites, lipodystrophies ou encore greffe d'ilots (Ryan 05, Vantyghem 08, Poggioli 08). Le but de ce travail etait de comparer les taux d'IL-7 serique chez des patients presentant des alterations de la masse grasse. Patients et methodes Dix patients souffrant d'un DID1 insulinoprive autoimmun, 10 patients DID 1 evalues 1 an apres greffe d'ilots, et 10 patients atteints de FPLD par...
1967-03-15
The aim of this work is to determine from both the theoretical and experimental points of view the type of distribution function for the electronic energies existing in a positive-column type cold laboratory plasma having an ionization rate of between 10{sup -6} and 10{sup -7}. The theoretical analysis, based on the imperfect Lorentz model and taking into account inelastic collisions is developed from the Boltzmann equation. The experimental method which we have employed for making an electrostatic analysis of the electronic energies makes use of a Langmuir probe used in conjunction with a transistorized electronic device. A comparison between the experimental and theoretical results yields information concerning the mechanisms governing electronic energy transfer on a microscopic scale. (author) [French] Le but de cette etude est de determiner d un double point de vue theorique et experimental le type de fonction de distribution des energies electroniques existant dans un plasma froid de laboratoire, du type colonne positive, dont le taux d ionisation est compris entre 10{sup -6} et 10{sup -7}. L'analyse theorique, basee sur le modele de Lorentz imparfait et tenant compte des collisions inelastiques est developpee a partir de l equation de Boltzmann. La methode experimentale d analyse electrostatique des energies electroniques que nous avons utilisee, met en jeu une sonde de Langmuir associee a un dispositif electronique a transistors. La comparaison des resultats experimentaux et theoriques nous fournit une connaissance des mechanismes qui regissent le transfert de l energie electronique a l echelle microscopique. (auteur)
The Health Hazards of Depleted Uranium Munitions: Part I
This first part of a twopart series by the British Royal Society evaluates the radiological risks posed by exposure to depleted uranium (DU), especially for troops on the battlefield. The Royal Society investigative panel primarily concerned itself with examining internal depleted uranium exposure from ingestion, inhalation, and wounds. The scientists reviewed the epidemiological data available on DU and estimated what the typical and worstcase levels of exposure for troops would be. The panel calculated the levels of radiation that troops in those categories would be exposed to and concluded that the DU would have only negligible effects on their health. The scientists found it highly unlikely that radiation exposure from DU would lead to statistically significant increases in cancer levels among the exposed, although there was a greater likelihood in the worstcase scenarios. The panel also made suggestions about further research that should be conducted regarding the radiological effects of depleted uranium.
CERN in Focus 1re dition. Le Service Audiovisuel vous propose un panorama des dernires vidos tournes au CERN. En effet, toutes les six semaines, nous vous prsenterons l'ensemble des activits, du dmarrage du LHC la grille de calcul, en passant par les diffrentes expriences. Au sommaire de cette dition, la visite du premier ministre de Malte, CMS et la derniere descente du YE-1 Le depart des aimants UA1 pour le Japon La mise en marche des secteurs 4 et 5 Et enfin, ATLAS et la descente... BREVES Dernieres soudures LHC Derniers boulonnages LHC College leman Appel a candidature Open Day
Imaging of uterine cervix carcinoma; L'imagerie du cancer du col uterin
2000-04-01
Imaging of uterine cervix carcinoma has evolved during the last decade. Recent developments in magnetic resonance imaging have expanded the role of MRI in evaluating the pathology of uterine cervix carcinoma. MRI is now the modality of choice for tumor staging, evaluating tumor response to treatment, diagnosing recurrences and for evaluating pregnant patients. MRI images will soon be used to calculate dosimetry for brachytherapy with matching and fusion software. (author)
1962-07-01
The object of this work is to study the influence of various physical factors on the rate of fluorination of solid plutonium tetrafluoride by fluorine. In a horizontal oven with a circulation for pure fluorine at atmospheric pressure and 520 deg. C, at a fluorine rate of 9 litres/hour, it is possible to transform 3 g of tetrafluoride to hexafluoride with about 100 per cent transformation and a recovery yield of over 90 per cent, in 4 to 5 hours. The fluorination rate is a function of the temperature, of the fluorine flow-rate, of the crucible surface, of the depth of the tetrafluoride layer and of the reaction time. It does not depend on the diffusion of the fluorine into the solid but is determined by the reaction at the gas-solid interface and obeys the kinetic law (1 - T{sub T}){sup 1/3} = kt + 1. The existence of intermediate fluorides, in particular Pu{sub 4} F{sub 17}, is confirmed by a break in the Arrhenius plot at about 370 deg. C, by differences in the fluorination rates inside the tetrafluoride layer, and by reversible colour changes. The transformation to hexafluoride occurs with a purification with respect of the foreign elements present in the initial plutonium. Recovery of plutonium from waste dross: The study is based on the transformation of occluded plutonium particles to gaseous hexafluoride which is then decomposed thermally to the tetrafluoride which can be reintroduced directly in the production circuit. Under the conditions considered this process is not applicable industrially. After milling, it is possible to separate the dross into enriched (75 per cent Pu in 2.6 per cent by weight of dross) and depleted portions. By prolonged fluorination (16 hours) of the various fractions it is possible to recover about 80 per cent of the plutonium. A treatment plant using fluidization, as described at the end of this study, should make it possible to substantially improve the yield. (author) [French] L'objet de l'etude est l'influence des differents facteurs physiques sur la vitesse de fluoration du tetrafluorure de plutonium solide par le fluor. Dans un appareil a four horizontal et circulation de fluor a la pression atmospherique de 520 deg. C, avec un debit de fluor pur de 9 l.h{sup -1}, il est possible de transformer une charge de 3 g de tetrafluorure en hexafluorure avec un taux de transformation d'environ 100 pour cent et un rendement de recuperation superieur a 90 pour cent, en 4 a 5 h. La vitesse de fluoration est fonction de la temperature du debit de fluor, de la surface de la nacelle, de l'epaisseur de la couche de tetrafluorure et du temps de reaction. Elle ne depend pas de la diffusion du fluor dans le Solide mais est commandee par la reaction a l'interface gaz-solide et suit la loi cinetique (1 - T{sub T}){sup 1/3} = kt + 1. L'existence de fluorures intermediaires, en particulier Pu{sub 4} F{sub 17}, est confirmee par une cassure de la droite d'Arrhenius vers 370 deg. C, par des differences dans les vitesses de fluoration au sein de la couche de tetrafluorure et par des variations reversibles de coloration. La transformation en hexafluorure s'accompagne d'une purification vis-a-vis des elements etrangers entrant dans la composition de plutonium initial. Recuperation du plutonium des scories d'elaboration: L'etude est basee sur la transformation en hexafluorure gazeux des grains de plutonium occlus dans les scories d'elaboration, cet hexafluorure devant fournir par decomposition thermique un tetrafluorure directement recyclable au stade elaboration. - Dans les conditions envisagees, ce procede n'est pas utilisable industriellement. Apres broyage, une Reparation par milieu dense (iodure de methylene) permet de separer une scorie enrichie en plutonium (75 pour cent du Pu dans 2,6 pour cent du poids des scories) et une scorie pauvre. Par fluoration prolongee (16 h) des diverses portions recueillies, il est possible de recuperer environ 80 pour cent du plutonium. Un appareillage de traitement base sur la fluidisation decrit a la fin de cette etude, devrait permettre d'ameliorer sensiblement le rendement. (auteur)
A three-dimensional mathematical model to simulate regional groundwater flow was used in the lower Palar River basin, in southern India. The study area is characterised by heavy ion of groundwater for agricultural, industrial and drinking water supplies. There are three major pumping stations on the riverbed apart from a number of wells distributed over the area. The model simulates groundwater flow over an area of about 392 km2 with 70 rows, 40 columns, and two layers. The model simulated a transient-state condition for the period 1991-2001. The model was calibrated for steady- and transient-state conditions. There was a reasonable match between the computed and observed heads. The transient model was run until the year 2010 to forecast groundwater flow under various scenarios of overpumping and less recharge. Based on the modelling results, it is shown that the aquifer system is stable at the present rate of pumping, excepting for a few locations along the coast where the groundwater head drops from 0.4 to 1.81 m below sea level during the dry seasons. Further, there was a decline in the groundwater head by 0.9 to 2.4 m below sea level in the eastern part of the area when the aquifer system was subjected to an additional groundwater withdrawal of 2 million gallons per day (MGD) at a major pumping station. Les modles mathmatiques en trois dimensions de l'coulement souterrain rgional sont trs utiles pour la gestion des ressources en eau souterraine, car ils permettent une valuation des composantes des processus hydrologiques et fournissent une description physique de l'coulement de l'eau dans un aquifre. Une telle modlisation a t entreprise sur une partie du bassin infrieur de la rivire Palar, dans le sud de l'Inde. La zone d'tude est caractrise par des prlvements importants d'eau souterraine pour l'agriculture, l'industrie et l'eau potable. Il existe trois grandes stations de pompage sur la rivire en plus d'un certain nombre de puits rpartis dans cette rgion. Le modle simule l'coulement souterrain dans une rgion d'environ 392 km2 avec 70 rangs, 40 colonnes et deux couches. Le modle a fonctionn en rgime transitoire en utilisant une approximation aux diffrences finies d'une quation diffrentielle partielle en trois dimensions de l'coulement souterrain dans cet aquifre pour la priode 1991-2001. Le modle a t calibr pour des conditions de rgime permanent et transitoire. Les charges hydrauliques calcules taient en bon accord avec celles observes. Sur la base des rsultats du modle, il est apparu que le systme aquifre est stable pour ce taux de pompage, except en quelques sites le long de la cte o l'eau marine a pntr 50-100 m dans les terres. Le modle transitoire a tourn jusqu'en 2010 afin de prvoir l'coulement souterrain dynamique pour diffrents scnarios de pompage excessif et de recharge rduite. Il se produit un abaissement de la pizomtrie de la nappe de 0.6 0.8 m dans la partie orientale, alors que l'aquifre est soumis un prlvement supplmentaire de 8,000 m3/jour l'une des stations principales de pompage. Mme avec le niveau actuel de pompage, la pizomtrie de la nappe descendrait sous le niveau de la mer au cours des saisons sches. Le modle prdit le fonctionnement du systme aquifre sous diffrentes conditions de stress hydrologique. Los modelos tridimensionales de flujo de aguas subterrneas son tiles para gestionar los recursos hdricos subterrneos, ya que proporcionan una aproximacin a los diversos procesos hidrolgicos y una descripcin cuantitativa del flujo de agua en el acufero. Se ha desarrollado un estudio de modelacin de este tipo en una parte de la cuenca baja del ro Palar, en el Sur de la India. Esta zona se caracteriza por las intensas extracciones de aguas subterrneas para usos agrcolas, industriales y domsticos. Hay tres estaciones de bombeo principales en el ro, adems de numerosos pozos distribuidos por la zona. El modelo simula el flujo de las aguas subterrneas en una superficie de 392 km2 por medio de 70 filas, 40 columnas y 2 capas. El modelo ha sido empleado en condiciones transitorias, por medio de la aproximacin en diferencias finitas de las ecuaciones diferenciales parciales en tres dimensiones del flujo en el acufero durante el perodo 1991-2001. Se ha calibrado el modelo en condiciones permanentes y transitorias. El ajuste entre los niveles calculados y medidos es razonable. A partir de los resultados de la modelacin, se ha obtenido que el sistema acufero es estable con la tasa de bombeo utilizada, exceptuando unos pocos emplazamientos a lo largo de la costa, donde se ha dado lugar a fenmenos de intrusin marina en una distancia de 50-100 m. El modelo transitorio ha sido ejecutado hasta el ao 2010 para predecir el flujo dinmico bajo diversos escenarios de sobreexplotacin y de reduccin de la recarga. Se produce una disminucin en los niveles piezomtricos de 0.6 a 0.8 m en la zona oriental, donde el sistema acufero est sometido a una extraccin adicional de 2 millones de galones por da en la estacin principal de bombeo. Incluso con las extracciones actuales, los niveles piezomtricos se sitan bajo el nivel del mar durante las pocas secas. El modelo predice el comportamiento de este sistema acufero bajo varias condiciones de presin hidrolgica.
1964-07-01
The theoretical study of the capture of charged particles injected longitudinally into a modulated magnetic configuration of the type proposed by Sinelnikov is extended by the use of the idea of a limited surface. This makes it possible to define the injection conditions which seem to lead to longer confinement times. The injection proposed is effected in the neighbourhood of a trajectory which is asymptotic to equilibrium trajectory situated in the plane of a mirror. Under these conditions the limiting surface is almost completely closed to the mirrors. The initial magnetic moment is no longer zero but has already the maximum value compatible with a penetration of the first mirror. A very small increase in the magnetic moment is then sufficient to ensure the capture of the particles; this is easily attained with a very low modulation factor. It is shown that capture can occur without modulation by a simple non-adiabatic effect due to the curvature of the field in the neighbourhood of the mirrors. A study is made of the influence on the capture in these conditions of a weak parasitic component of the magnetic field which is perpendicular to the axis of revolution of the main configuration. (authors) [French] L'etude theorique de la capture de particules chargees injectees longitudinalement dans une configuration magnetique modulee du type propose par Sinelnikov est etendue par l'utilisation de la notion de surface limite. Ceci permet de definir des conditions d'injections qui semblent devoir conduire a des temps de confinement plus longs: L'injection proposee est faite au voisinage d'une trajectoire asymptote a la trajectoire d'equilibre situee dans le plan d'un miroir. Dans ces conditions la surface limite est presque completement fermee aux miroirs. Le moment magnetique initial n'est plus nul mais possede deja la valeur maximum compatible avec la penetration a travers le premier miroir. Un tres faible accroissement du moment magnetique est alors suffisant pour assurer la capture des particules, ce qui est aisement obtenu avec un taux tres faible de modulation. On demontre la possibilite de capture sans modulation, par un simple effet non adiabatique du a la courbure du champ au voisinage des miroirs. On etudie l'influence sur la capture obtenue, d'une composante parasite faible de champ magnetique, de direction perpendiculaire a l'axe de revolution de la configuration principale. (auteurs)
1964-07-01
There are still many problems in the field of measurement and control of neutron flux. The present studies in connexion with high flux reactors contribute to the solution of these problems which concern specialists in reactor control. The present state of this investigation and the results of different studies carried out in France by the C A and the EDF are pointed out: A - In the nuclear instrumentation field, work is at present devoted to the technologies used to develop detectors and cables, which have to work at high temperature and in a high {gamma} background; fast electronic techniques are applied to fission counters to measure low neutron fluxes in a high {gamma} background (10 Rh). B - In the control and safety field, there is a real need for studies on the behaviour of reactors in the subcritical state. This increases the margin of security during restarts when poison effects must be overcome The perturbations due to control rod movements necessitate a new organisation of power level safety and control assemblies, in connexion with thermal or activation measurements. Two methods of fast start-up are described. They are related to the fission rate measurement as a function of time. This is done either continuously by a constant and high reactivity change, or step by step. The application of automatic techniques to detector motion seems to give the answer to control and safety in normal start-up. C - The scope of these studies covers the methods used for the control of E.D.F. 3, which are described. (authors) [French] La mesure et le controle du flux neutronique dans les piles de puissance posent encore de nombreux problemes. Les etudes actuellement entreprises dans le domaine des piles a haut flux, doivent apporter une contribution importante a la solution de ces problemes qui interessent les specialistes du controle des piles de puissance. On analyse l'etat actuel de ces etudes et on donne les resultats des differents travaux effectues en France, dans les differents laboratoires du Commissariat a l'Energie Atomique et de l'Electricite de France. A - Dans le domaine de l'instrumentation, ces etudes portent actuellement sur les technologies utilisees pour le developpement des detecteurs et cables susceptibles de fonctionner a haute temperature; sous rayonnement {gamma} eleve - et sur les techniques d'electronique rapide appliquees aux chambres a fissions qui permettent de faire des mesures de flux neutronique sous rayonnement {gamma} eleve (105 R/h). B - Dans le domaine general du controle et de la securite, les difficultes de redemarrage liees aux empoisonnements par les produits de fission conduisent a des etudes approfondies sur le comportement du reacteur en regime sous-critique. Les perturbations apportees aux mesures neutroniques par le mouvement des barres de controle necessitent une nouvelle organisation des chaines de mesure et de securite neutronique faisant intervenir au niveau de puissance des parametres correcteurs tels que: puissance thermique, temperature, activation Azote 16. En ce qui concerne les demarrages rapides, deux methodes nouvelles sont decrites liees essentiellement a la mesure du taux de fissions en fonction du temps, soit dans le cas d'une liberation continue a vitesse constante et elevee de reactivite, soit dans le cas d'une liberation de reactivite par paliers. Par ailleurs, l'application des techniques de deplacement automatique des detecteurs dans le cas des demarrages normaux semblent apporter une solution rationnelle au controle et a la securite. C - Dans le cadre des techniques ci-dessus, on decrit les dispositifs retenus pour la mesure et le controle de la puissance de la pile EDF III. (auteurs)
QUELQUES ELEMENTS DE LACTIVITE DE LA CAISSE EN 2006
2007-10-11
$$bThe complete translation of the article will be available next week.Composition du Conseil dadministration (au 31 dcembre 2006) Membres Nomms par E. Chiaveri (supplant : T. Lagrange) Directeur gnral du CERN D. Duret (supplant : G. Deroma) Association du personnel du CERN F. Ferrini (supplant : D.-O. Riska) Conseil du CERN R. Fischer (supplant : K. Banse) Directeur gnral de lESO C. Hauviller (supplant : G. de la Fuente) lu par les membres de la Caisse J. Lahaye (supplant : P. Martel) lu par les membres de la Caisse P. Levaux (supplant : F. Bello) Conseil du CERN J.-P. Matheys (supplante : F. Ranjard) lu par les membres de la Caisse S. Myers (supplant : F. Sonnemann) lu par les membres de la Caisse A.J. Naudi (supplant : P. Geeraert) Directeur gnral du CERN Observateur des bnficiaires J.-F. Barthlemy (supplant : F. Wittgenstein) Conseil dadministration en accord avec lAssociation du personnel Bureau de la prsidence F. Ferrini, Prsident nomm par le Conseil du CERN J.-P. Matheys, Vice-prsident A.J. Naudi, Vice-prsident Administrateur : C. Cunoud nomm par le Conseil du CERN sur proposition du Conseil dadministration en accord avec le Directeur gnral.Membres Leffectif des membres indiqu dans le graphique ci-dessous est celui des membres prsents au 31 dcembre 2006. En 2006, le nombre des membres de la Caisse a augment de 46 units (270 dparts/316 arrives), en raison principalement dune lgre progression tant des effectifs du CERN que ceux de lESO, pour se situer en fin danne 3258 membres. Lge moyen des membres de la Caisse fin 2006 tait de 41 ans et 3 mois pour les femmes et de 43 ans et 7 mois pour les hommes. Bnficiaires Au cours de lanne 2006, leffectif total des bnficiaires est pass de 2947 3017. Le graphique ci-aprs donne la rpartition des bnficiaires par catgorie, lexclusion des participants au Programme de Retraite Progressive (PRP). Evolution des prestations Le graphique ci-dessous illustre les montants des diffrents types de prestations verses par la Caisse au cours de lanne considre et, aux fins de comparaison, ceux de 2005. En chiffres absolus, laugmentation totale est de 15,2 MCHF ou 6,4 % par rapport lanne prcdente, le montant total des prestations verses slevant 251,9 MCHF, produisant en 2006 un cash flow ngatif entre contributions encaisses et prestations payes de 109,7 MCHF absorb par le revenu des placements. Situation financire Lvolution globale de la situation financire de la Caisse au cours de lanne 2006 est prsente ci-aprs dune manire trs rsume. Notons que les mouvements comptables globaux de la Caisse, cest--dire laddition du rsultat des placements au prix du march en fin danne, en tenant compte des rectifications de valeur, et du solde entre contributions et prestations, est 264 MCHF. Cette progression importante sexplique par des plus-values trs positives sur toutes les classes dactifs gres par la Caisse qui ont conduit une trs bonne performance globale. En millions de francs suisses (arrondis) Rpartition des avoirs La rpartition des investissements en diffrentes catgories de placement joue un rle trs important dans la gestion de la Caisse. La rpartition des avoirs en pour cent pour lanne 2006 figure au graphique ci-dessous ; titre de comparaison, ce mme graphique prsente la situation fin 2005. Rappelons qu chaque catgorie davoirs est associ un couple risque/rendement et que les tudes faites ont dmontr que si la Caisse voulait atteindre son objectif de rendement long terme, qui a t fix selon les nouvelles hypothses actuarielles 5 % (CERN/2637 CERN/FC/4993), elle devait, en moyenne, tre investie raison de 40 % en actions. Laugmentation de la part actions du portefeuille en 2006 est attribuable avant tout un effet mcanique de hausse des marchs, mais elle a t accompa-gne et amplifie par des investissements cibls sur les marchs asiatiques essentiellement. Notons quen 2006, cest limmobilier qui a connu laugmentation de valeur la plus importante, en enregistrant une performance globale de 14,6 %. Mais dans lensemble, toutes les classes dactifs ont connu des rsultats satisfaisants. En outre, leuro stant renforc par rapport au franc suisse de + 3,2 %, cette monnaie a galement contribu amliorer les rsultats densemble. Rsultats de la Caisse de pensions en 2006 Avec une performance globale de + 9 %, la Caisse enregistre nouveau un excellent rsultat qui permet la Caisse de voir son taux de couverture samliorer sensiblement. Notons titre de comparaison que la performance moyenne des caisses suisses a t de 6,7 %. Alors quen 2005 le portefeuille des actions avait enregistr une performance de + 25,7 %, la performance de cette classe dactifs stablit + 12,7 % en 2006. A titre indicatif, lindice des actions internationales selon Morgan Stanley Capital International (MSCI Monde) sest amlior de 11,2 %. En ce qui concerne la part des avoirs investis en obligations, le rsultat densemble a t de 2,4 %, alors que lindice de rfrence JP Morgan a recul de 1,2 %. A noter que le programme de couverture montaire a enregistr un dficit de 3,8 MCHF d essentiellement la faiblesse du dollars US. Le portefeuille immobilier a eu en 2006 une performance de 14,6 % par rapport la valeur moyenne des biens. Dans ce secteur, les apprciations ngatives dues la situation en Allemagne et aux Pays-Bas ont t compenses par un bilan positif en France, en Suisse et en Grande Bretagne. Durant lanne 2006, tous les grands marchs ont eu des performances positives. Ce fut tout particulirement le cas des marchs europens et asiatiques hors Japon dont les progressions respectives ont t de 23,6 % et 19,4 %. Situation actuarielle en caisse ferme Comme le souligne lactuaire dans son rapport joint au rapport annuel 2006 de la Caisse, lexercice 2006 a enregistr de bonnes performances boursires. Cet aspect a dj contribu amliorer la situation de la Caisse fin 2006, dbut 2007, puisque le degr de couverture est pass 104,7 % au 1
Les difficultes d'interpretation du bilan martial
2008-01-01
Summary Accurate iron status assessment remains challenging for our laboratories. Iron measurement is performed only to calculate transferrin saturation (TS) which is the screening test for hemochromatosis (TS
A timeon model of quark and lepton mass matrices
2009-01-01
It is proposed that T violation in physics, as well as the masses of electron and u,d quarks, arise from a pseudoscalar interaction with a new spin 0 field tau(x), odd in P and T, but even in C. This interaction contains a factor igamma5 in the quark and lepton Dirac algebra, so that the full Hamiltonian is P,T conserving. But by spontaneous symmetry breaking, the new field tau(x) has a nonzero expectation value not =0 that breaks P and T symmetry. Oscillations of tau(x) about its expectation value produce a new particle, the 'timeon'. The mass of timeon is expected to be high because of its flavor-changing properties. The main body of the paper is on the low energy phenomenology of the timeon model. As we shall show, for the quark system the model gives a compact three-dimensional geometric ...
1964-07-01
The observation of the behaviour of water and heavy water in working reactors contributes to their safe running and provides information useful in studies relating to reactivity control techniques using soluble poisons. The use of nuclear poisons dissolved in the water of a reactor leads to its chemical pollution. The conditions under which they can be used without causing the undesirable effects of this pollution are studied. Problems of analysis, although important, are not tackled in this paper. Behaviour of heavy water in working reactors. Isotopic pollution of heavy water: The rate at which this pollution occurs depends on the type of reactor and on certain characteristic incidents. The use of a re-concentration column is an efficient way of maintaining the heavy water isotopic concentration in a reactor which cannot be considered exempt from slow isotopic pollution. Heavy water leak detection: The instantaneous rates of small leaks can be measured, the leak localised, and the atmospheric contamination in the reactor building checked. Isotopic analysis for deuterium or tritium determination, is carried out on samples. Chemical pollution and purification of heavy water Chemical pollution of heavy water is one of the most complex problems in reactor chemistry Corrosion of the materials which make up the core and the heavy water circuits varies extensively with the state of purity of the heavy water, as may be appreciated from the performances of the purification circuits and from direct measurements From the knowledge acquired it has been possible to work out standards of purity which, if observed will guarantee satisfactory running of the reactor. Radiolytic decomposition of heavy water : A better knowledge of its quantitative aspects in reactors is necessary in order to foresee the amounts of explosive gas mixture given off in power reactors. The radiolysis rate develops with the chemical purity of the water and the instantaneous power of the reactor Experience of the CEA heavy water reactors and a systematic study of the radiolytic decomposition of water in the core of swimming-pool reactors are described. Setting up of reactivity control by physico-chemical methods. Reactivity control by homogeneous poisoning of the reactor A comparison of the evolution of xenon poisoning with the residual anti reactivity of the poison in solution during its nuclear consumption establishes the programme which must govern the variation in its concentration if the exact compensation is to be produced The behaviour of the poison towards the reactor materials under the particular operational conditions must be taken into account. Radiolytic decomposition of water in the reactors in the presence of soluble poisons: A study of the effect of certain chemically inert salts, present in small concentrations in the water, on its radiolytic decomposition rate, has led to some new results which are discussed. The choice of a soluble poison is justified on the basis of the above results. Reactivity control by the use of a gaseous absorbent The use of a gas control rod circuit for compensation purposes, in place of solid control rods is described. The use of soluble poisons in the moderator to compensate the xenon effect, and of a gaseous absorbent in a circuit known as a gas control rod form original aspects of the reactivity control in the reactor EL 4. (authors) [French] L'observation du comportement de l'eau et de l'eau lourde dans les reacteurs en exploitation, contribue au fonctionnement sur de ceux-ci et oriente certaines etudes relatives aux techniques de controle de la reactivite par mise en oeuvre de poisons solubles. L'utilisation de poisons nucleaires dissous dans l'eau du reacteur entraine une pollution chimique de celle-ci. Les conditions d'emploi permettant d'eviter les effets indesirables de cette pollution sont etudiees. Les problemes analytiques - bien qu'importants - ne sont pas abordes dans le cadre de la communication. 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 nucleaire permet de fixer le programme que doit respecter la variation de sa concentration afin de produire la compensation exacte. Le comportement du poison vis-a-vis des materiaux constituant le reacteur dans les conditions particulieres du fonctionnement doit etre respecte. Decomposition radiolytique de l'eau dans les reacteurs en presence de poisons solubles: L'etude de l'effet de certains sels chimiquement inertes, en faible concentration dans l'eau, sur la vitesse de sa decomposition radiolytique a conduit a des resultats nouveaux qui sont discutes. Le choix du poison soluble est justifie en fonction des resultats precedents. Controle de la reactivite par utilisation d'un element absorbant gazeux: L'application d'un circuit de barre gazeuse a la fonction de compensation en remplacement des barres de compensation solides est exposee. L'utilisation des poisons solubles dans le moderateur pour compenser l'effet Xenon et celle d'un absorbant gazeux dans un circuit dit barre de compensation gazeuse constituent des aspects originaux du controle de la reactivite dans le reacteur EL 4. (auteurs)
1987-01-01
Measurement was made of the reaction rate distributions for /sup 238/U(n,f), /sup 235/U(n,f), /sup 238/U(n,..gamma..), /sup 27/Al(n,..cap alpha..) and /sup 58/Ni(n,p) in a large depleted uranium (DU) pile. The pile consisted of DU blocks forming a spherical shell of 45.72 cm radius and 40.64 cm thick. 14-MeV neutrons were generated at the center. Fast neutron leakage spectrum was also measured by an NE-213 spectrometer. In order to assess the /sup 238/U neutron cross sections of JENDL-2, the experiment was analyzed using the Monte-Carlo transport code MCNP with continuous energy cross sections. The agreement between the calculation and the experiment is generally unsatisfactory. The ratios of calculation to experiment of low energy reactions decreased with the thickness of the DU layer. The analysis of the Livermore pulsed sphere experiment for the small DU sphere revealed underestimation of leakage neutron spectrum around 10 MeV. The /sup 238/U cross sections of JENDL-2 should be improved for 14-MeV neutronics calculation.
Microstructures and rheology of the Earth's upper mantle inferred from a multiscale approach
2010-01-01
RsumLa forte anisotropie rhologique des polycristaux d'olivine, associe leur microstructure, est un aspect majeur affectant la dynamique du manteau terrestre suprieur. Des expriences de dformation sous haute pression et en rayonnement synchrotron de monocristaux d'olivine, compltes par des calculs ab initio de friction de rseau, montrent une transition du systme mou depuis [100] vers [001] quand la pression et la temprature (et donc la profondeur in situ) augmentent. Nous avons introduit ces donnes l'chelle du systme de glissement dans l'extension du second-ordre du schma auto-cohrent afin d'apprhender les volutions de microstructure le long d'un coulement typique sous une dorsale ocanique.
1965-05-01
We have studied the variation of the parameters of {alpha} plutonium and aluminium stabilised {delta} alloys at low temperature, in order to verify the existence of an antiferromagnetic transition at low temperature. The effects of {alpha} particles on the length of a polycrystal of {alpha} plutonium at 4,2 deg. K are also presented at 18 deg. K a plutonium shows no crystallographic change from its structure at room temperature. The thermal expansion coefficients along the 3 axis seem to be positive at this temperature. Therefore a magnetic contribution on thermal expansion coefficients must be small. A dilatation anomaly of {delta}Pu has been observed at 100 deg. K, together with an anomaly of the diffraction lines intensity. No sur-structure line has been observed at 20 deg. K. The length of {alpha} plutonium Increases with time at a rate of about 5 x 10{sup -6} per hour when held in liquid helium. This effect is attributed to the creation of Frenkel pairs. (author) [French] On presente une etude cristallographique a basse temperature du plutonium {alpha} et stabilise {delta} par des additions d'aluminium en vue de verifier l'existence d'une transformation antiferromagnetique a basse temperature. L'effet des particules {alpha} a 4,2 deg. K sur la longueur d'un polycristal de plutonium {alpha} a egalement ete etudie. Il a ete determine que le plutonium {alpha} ne mange pas de phase allotropique Jusqu'a 18 deg. K, les coefficients de dilatation des trois axes de la maille semblent rester positifs. Une eventuelle contribution magnetique sur les coefficients de dilatation devrait donc etre faible. Une legere anomalie de dilatation de Pu {delta} a ete observee a 100 deg. K ainsi qu'une anomalie d'intensite des raies de diffraction. Aucune raie de surstructure n'a ete observee. Le plutonium {alpha} s'allonge lorsqu'il est plonge dans l'helium liquide d'un taux de l'ordre de 5 x 10{sup -6}/heure. Cet effet a ete attribuee a la creation de paires de Frenkel. (auteur)
1963-06-15
With a view to discovering whether low irradiation doses are liable to increase the incidence of leukemia or cancer amongst people exposed to this risk, an enquiry, has been undertaken into the distribution according to age and to sex of 13,596 important radiological examinations carried out in radio-pediatric departments from 1953 to 1961, a population structure study essential for choosing the group studied and the comparison group. This survey will be used as the basis for the constitution of a population whose pathology will be examined with great care. The main conclusion resulting from this enquiry is that the frequency of digestive and urinary examinations is very high in babies of under one year old and higher in boys than in girls. (author) [French] Dans le but de determiner si les faibles doses d'irradiations sont susceptibles d'augmenter le taux de leucemies ou de cancer dans les populations exposees a ce risque, une enquete a ete faite sur la repartition par age et par sexe de 13596 examens radiologiques importants effectues dans des services de radiopediatrie de 1953 a 1961, elude de la structure de la population necessaire pour choisir le groupe etudie et le groupe temoin. Ce releve sert de base a la constitution d'une population dont la pathologie sera recherchee avec soin. De cette enquete, il ressort essentiellement que la frequence des examens digestifs et urinaires est tres elevee chez les nourrissons ages de moins d'un an, et plus elevee chez les garcons que chez les filles. (auteur)
1954-07-01
Crystal growth often interferes in the analysis of orientation textures of annealed sheets; in order to achieve the hitting of a great number of grains by the X-ray beam, the sample must be moved in its own plane, the rolling direction remaining parallel to itself. For the study of rolled uranium annealing, one linear scanning was found insufficient; therefore the authors developed a double scanning sample holder allowing the survey of a surface up to 6 or 8 cm{sup 2}. Thus, for recrystallized samples with a grain diameter up to 1 mm, continuous diffraction lines can be obtained. The first diagrams confirm the dilatometric results relating to the texture changes due to {alpha} annealing hard-rolled sheets or to the {alpha}-{beta} allotropic transformation. (author) [French] L'analyse des textures d'orientation des toles apres recuit est souvent genee par le grossissement des cristaux; pour que le faisceau de rayons X frappe toujours un grand nombre de cristaux, on est alors conduit a deplacer l'echantillon dans son plan, la direction de laminage restant parallele a elle eme. Dans l'etude du recuit de l'uranium lamine, un balladage lineaire est insuffisant; c'est pourquoi on a realise un porte chantillon a double balladage permettant l'exploration d'une surface de 6 a 8 cm{sup 2}; on obtient ainsi des anneaux de diffraction continus avec des echantillons recristallises a grains de diametre inferieur ou egal a 1 mm. Les premiers cliches effectues avec cet appareil ont confirme les resultats dilatometriques concernant le changement de texture par recuit en phase {alpha} des toles laminees a fort taux d'ecrouissage, ainsi que le changement de texture au passage de la transformation allotropique {alpha}-{beta}. (auteur)
Repository criticality control for 233U using depleted uranium
1999-01-01
The US is evaluating methods for the disposition of excess weapons-usable 233U, including disposal in a repository. Isotopic dilution studies were undertaken to determine how much depleted uranium (DU) would need to be added to the 233U to minimize the potential for nuclear criticality in a repository. Numerical evaluations were conducted to determine the nuclear equivalence of different 235U enrichments to 233U isotopically diluted with DU containing 0.2 wt% 235U. A homogeneous system of silicon dioxide, water, 233U, and DU, in which the ratio of each component was varied, was used to determine the conditions of maximum nuclear reactivity. In terms of preventing nuclear criticality in a repository, there are three important limits from these calculations. 1. Criticality safe in any nonnuclear ...
Pulsed D-D Neutron Generator Measurements of HEU Oxide Fuel Pins
2009-01-01
Pulsed neutron interrogation measurements have been performed on highly enriched uranium (HEU) oxide fuel pins and depleted uranium (DU) metal using a D-D neutron generator (2 x 106 neutrons-s-1) and moderated 3He tubes at the Idaho National Laboratory Power Burst Facility. These measurements demonstrate the ability to distinguish HEU from DU by coincidence counting using a pulsed source. The amount of HEU measured was 8 kg in a sealed 55-gallon drum compared to 31 kg of DU. Neutron events were counted during and after the pulse with the Nuclear Materials Identification System (NMIS) and used to calculate the neutron coincidence time distributions. Passive measurements were also performed for comparison with the pulsed measurements. This paper presents the neutron coincidence distribution and Feynman variance results from the ...
Incentives for the use of depleted uranium alloys as transport cask containment structure
1992-01-01
Radioactive material transport casks use either lead or depleted uranium (DU) as gamma-ray shielding material. Stainless steel is conventionally used for structural containment If a DU alloy had sufficient properties to guarantee resistance to failure during both normal use and accident conditions to serve the dual-role of shielding and containment, the use of other structure materials (i.e., stainless steel) could be reduced. (It is recognized that lead can play no structural role.) Significant reductions in cask weight and dimensions could then be achieved perhaps allowing an increase in payload. The mechanical response of depleted uranium has previously not been included in calculations intended to show that DU-shielded transport casks will maintain their containment function during all conditions. This paper describes a two-part study of depleted uranium ...
Calculating Capstone Depleted Uranium Aerosol Concentrations from Beta Activity Measurements
2009-01-01
Beta activity measurements were used as surrogate measurements of uranium mass in aerosol samples collected during the field testing phase of the Capstone Depleted Uranium (DU) Aerosol Study. These aerosol samples generated by the perforation of armored combat vehicles were used to characterize the depleted uranium (DU) source term for the subsequent human health risk assessment (HHRA) of Capstone aerosols. Establishing a calibration curve between beta activity measurements and uranium mass measurements is straightforward if the uranium isotopes are in equilibrium with their immediate short-lived, beta-emitting progeny. For DU samples collected during the Capstone study, it was determined that the equilibrium between the uranium isotopes and their immediate short lived, beta-emitting progeny had been disrupted when penetrators had perforated target vehicles. ...
Tropospheric ozone in east Asia
1996-12-31
An analysis of the observed data for the tropospheric ozone at mid latitudes in east Asia is done. There are three ways by which the tropospheric ozone is calculated, namely: (1) Ozonesonde measurements, (2) Fishman`s method of Residual Ozone and (3) TOMS measurements - an indirect method of calculating tropospheric ozone. In addition the surface ozone values at the network sites in Japan is also considered. The analysis of data is carried out for a period of twelve years from 1979 to 1991. In general it is observed that the tropospheric ozone is more in summer than winter, obviously because of the larger tropopause height in summer. On an average for the period of the analysis, the ozone values are at a high of about 60 DU (dobson units). While in winter the values go down to around 30 DU. Also a time series analysis shows an increasing trend in the values over the years. The ozonesonde values are correlated more to the TOMS tropospheric ozone values. For the stations analyzed in Japan, the TOMS tropospheric ozone values are generally greater than the ozonesonde values. The analysis of the average monthly surface ozone in Japan shows highs in spring and lows in summer. This can be attributed to movement of pollutant laden fronts towards Japan during spring. The highs for surface ozone are about 50 DU while the lows are around 20 DU.
1967-07-01
The cadmium correction factor is defined and measured by the Tittle method for the gold. The author shows that this factor is constant in function of the detector thickness and that the resonant part of the cross section is preponderant for its determination. This property is needful to the cadmium correction factor calculation if, as usual, the effective cut energy variation of the filter is not taken into account with the detector thickness and the cadmium thickness. (A.L.B.) [French] Le facteur de correction cadmium est defini, calcule et mesure par la methode de TITTLE pour l'or. On montre qu'il est constant en fonction de l'epaisseur du detecteur et que la partie resonnante de la section efficace est preponderante pour sa determination. Cette propriete est necessaire au calcul du facteur de correction cadmium, si, comme il est fait souvent, on ne tient pas compte de la variation de l'Energie de coupure effective du filtre avec l'epaisseur du detecteur et l'epaisseur du cadmium. (auteur)
1964-07-01
This report presents the results of studies which seemed important to undertake in connexion with the development of fast neutron reactors. - It points out the advantage of high internal breeding ratios ({approx}1, 1) which are necessary in order to get a small change in time both in power distribution and reactivity (less: than 0.005 {delta}k/k in 18 months). - It shows how to achieve this goal, when simultaneously power distribution flattening is obtained. These results in a higher mean specific power (which is an economic gain) and therefore in a smaller doubling time (about 10 years). - It attempts to find criteria concerning the specific power that should be used in future reactor designs -It presents a conceptional design of a 1000 MWe fast neutron reactor, for the realisation of which no technological impossibility appears. - It shows that the dynamic behaviour seems satisfactory despite a positive total isothermal sodium coefficient. - It tries to predict the development of fast reactors within the future total nuclear program. It does not appear that fissile materials supply problems should in France slow down the development of fast neutron reactors, which will be essentially tied up to its economical ability to produce cheap electric power. (authors) [French] Ce rapport presente les etudes qu'il nous a paru important d'aborder dans le cadre du developpement des reacteurs a neutrons rapides. - Il met en evidence l'interet des taux de regeneration internes eleves ({approx}1, 1) pour obtenir une bonne evolution dans le temps de la distribution de puissance et de la reactivite (moins de 0,005 {delta}k/k pour 18 mois). - Il montre la possibilite d'y parvenir tout en applatissant la distribution des fissions, ce qui se traduit par une puissance specifique moyenne plus elevee (gain economique), et donc un temps de doublement plus faible de l'ordte de 10 ans - Il tente de definir un optimum de la puissance specifique valable pour les projets de reacteurs futurs. - Il presente un concept de reacteur a neutrons rapides de 1000 MWe, pour la realisation duquel aucune impossibilite technologique de realisation n'apparait. - Il indique que le comportement dynamique appatait satisfaisant, bien que le coefficient de reactivite isotherme du au sodium soit positif. - Il essaie de situer le developpement des reacteurs a neutrons rapides dans le cadre de l'expansion de l'energie nucleaire. L'approvisionnement en matieres fissiles ne semble pas devoir freiner en France le developpement des reacteurs a neutrons rapides. Celui - ci dependra essentiellement a moyen terme de leur competitivite economique. (auteurs)
L’évaluation et le traitement du nourrisson exposé au virus d’immunodéficience humaine de type 1
RÉSUMÉDans les pays industrialisés, des soins et un traitement sont offerts aux femmes enceintes et aux nourrissons, afin de faire chuter à 2 % ou moins le taux d’infection périnatale au virus d’immunodéficience humaine de type 1 (VIH-1). Le pédiatre joue un rôle de premier plan dans la prévention de la transmission du VIH-1 de la mère à l’enfant par le dépistage des nourrissons exposés au VIH dont l’infection au VIH de la mère n’a pas été diagnostiquée avant l’accouchement. Il prescrit une prophylaxie antirétrovirale à ces nourrissons, afin de réduire le risque d’acquisition de l’infection au VIH-1 et d’en éviter le plus possible la transmission par le lait maternel. De plus, le pédiatre peut soigner les nourrissons exposés au VIH-1 en les surveillant pour obtenir un dépistage précoce de l’infection au VIH-1 et évaluer les toxicités à court et à long terme de l’exposition aux antirétroviraux, assurer une chimioprophylaxie de la pneumonie à Pneumocystis et soutenir les familles qui vivent avec une infection au VIH-1, grâce à des conseils thérapeutiques aux parents ou aux soignants.
1969-07-01
One of the economic advantages of nuclear energy consists of the small proportional element in its cost structure. Economies of scale favour the nuclear station as compared with the conventional thermal one, and when the demand for electricity and heat, in particular for desalination, are sufficient, nuclear energy may, subject to certain conditions, prove advantageous. The object of this paper is to discuss the validity of the conclusions reached according to the hypotheses adopted. In the first part, the different kind of uncertainties connected with technical, economic and financial data (the various transmission coefficients, the life of equipment according to the choice of materials, changes in prices, the form of price functions and interest rates), and with the various constraints, are examined and discussed. In the second part the uncertainties connected with the method of optimisation used and the criterion of selection adopted are examined and discussed. It is shown thereby that it is usually extremely difficult to assume absolutely the competitiveness, or conversely the non-competitiveness, of using nuclear energy in the desalination of water, and that a large number of aspects have to be carefully examined. (author) [French] On sait que l'un des avantages economiques de l'energie nucleaire reside dans la faible part proportionnelle dans la structure de son cout. Les economies d'echelle favorisent le nucleaire par rapport au thermique classique, et lorsque les demandes d'electricite et de chaleur, notamment pour le dessalement, sont suffisantes on peut envisager favorablement, sous certaines hypotheses, le recours a l'energie nucleaire. L'objet de cette communication est de discuter la validite des conclusions auxquelles on parvient selon les hypotheses envisagees. Dans une premiere partie, on etudie et on discute les differentes sortes d'incertitudes, liees aux donnees techniques, economiques et financieres (les divers coefficients de transmission, les durees de vie des materiels, selon le choix des materiaux, l'evolution des prix, la forme des fonctions de prix et les taux d'interet) et aux contraintes. Dans une deuxieme partie, on etudie et on discute les incertitudes liees, a la methode d'optimisation utilisee et au critere de choix retenu. On montre ainsi qu'il est extremement difficile dans la plupart des cas de conclure sans nuances a la competitivite ou, a l'inverse, a la non competitivite du recours a l'energie nucleaire dans le dessalement des eaux et qu'un grand nombre d'aspects doivent etre soigneusement examines. (auteur)
1968-07-01
Dislocations in {alpha}-uranium were studied by electron microscopy. Electropolishing of thin foils was performed at low temperature (-110 deg. C) to prevent oxidation. Burgers vectors of twins dislocations are defined. Interactions between slip and twinning are studied from both experimental and theoretical point of view. Samples irradiated at several burn-up were examined. In order to explain our micrographic results, and also all information gathered in literature about radiation damage in {alpha}-uranium, a coherent model is propound for the fission particles effects. We analyse the influences of parameters: temperature, dislocation density, impurity content. The number of point defects created by one initial fission is determined for pure and annealed metal. The importance of the self-anneal which occurs immediately in each displacement spike, and the anneal due to a new fission on the damage resulting from a previous fission, are estimated. The focussing distance in [100] direction is found to be about 1000 Angstrom, at 4 deg. K. (author) [French] Ce travail est une etude par microscopie electronique des dislocations induites dans l'uranium {alpha}, soit par deformation plastique, soit par irradiation. Une methode de preparation des lames minces a basse temperature (-110 deg. C) a ete mise au point. Les vecteurs de Burgers des diverses dislocations de macles de ce metal ont ete definis. Les interactions glissements- maclages sont etudiees experimentalement et theoriquement. Des echantillons irradies a divers taux de combustion ont ete examines. Pour expliquer nos resultats micrographiques, et aussi l'ensemble des informations recueillies dans la litterature concernant l'endommagement par irradiation de l'uranium-{alpha}, nous proposons un modele coherent de l'effet des fragments de fission dans ce metal. L'influence des parametres: temperature, densite de dislocations, impuretes est analysee. Le nombre de defauts ponctuels crees par une fission dans du metal pur et recuit est determine; l'importance de l'autorecuit immediat dans chaque cascade de deplacement, et celle du recuit d'une fission sur les degats d'une fission anterieure sont estimees. Enfin, la distance de focalisation dans la direction [100] est trouvee egale a 1000 Angstroem, a 4 deg. K. (auteur)
1964-07-01
Anatomical and physiological data of the gastrointestinal tract of adults and children were summarized in a standard schema, to be used in calculating the levels of radioactive contamination, in the food chain. (author) [French] Cette note a pour objet de rassembler les donnees anatomiques et physiologiques du tractus gastrointestinal, chez l'adulte et chez l'enfant, et d'en deduire un schema standard qui puisse servir de base au calcul des niveaux de contamination de la chaine alimentaire par les substances radioactives. (auteur)
Dimensionnement des actionneurs lectriques aliments frquence variable sous faible tension
In Part I we present a multidisciplinary analysis model for the prediction of functional connections between the design variables and the electromagnetical, electrical and thermal performances of a brushless permanent magnet motor. In this paper we have elaborated a design methodology for electrical motors supplied from a variable-frequency low-voltage source. The objective is to take into account the influence of the inverter's dynamics from the beginning of the design, for the same reasons as we do for electromechanical and thermal constraints. The procedure is based on a Sequential Quadratic Programming optimization method. Two techniques are used to take into account the influence of the inverter: the first one develops the performance analysis with the multidisciplinary model; the second one considers the inverter's current reference as a supplementary optimization variable for the control of the design. Optimization difficulties linked to the chopping of the converter are discuted in connection with a sensitivity analysis of the torque, with respect to the inverter's current reference; a method is proposed to enhance the performances of the algorithm. The method has been applied to the design of a permanent magnet brushless DC motor used in the propulsion system of an electrical scooter; evolution of the design with the complexity level of analysis model is evidenced. Dans une premire partie nous avons dvelopp un modle d'analyse pluridisciplinaire qui tablissait les dpendances fonctionnelles entre les variables de conception et les performances magnto-lectro-thermiques d'un moteur brushless aimants permanents. Dans cet article nous dcrivons une procdure de dimensionnement adapte la conception de la machine alimente frquence variable sous faible tension. L'objectif est d'intgrer la dynamique du convertisseur lectronique ds la phase initiale du dimensionnement, au mme titre que les spcifications lectromcaniques et thermiques. La procdure est gre par une mthode d'optimisation dterministe de type Programmation Quadratique Squentielle. Elle intgre l'influence du convertisseur au moyen de deux spcificits : la premire consiste valuer les fonctions du problme d'optimisation sur la base du module d'analyse pluridisciplinaire ; la deuxime permet de contrler l'volution du dimensionnement au travers de variables d'optimisation dont la liste inclut les consignes de la commande en courant du convertisseur. Les difficults d'optimisation lies au mode de fonctionnement discret du convertisseur sont discutes au regard du calcul de la sensibilit du couple lectromagntique envers la consigne de courant du convertisseur ; une mthode est propose pour assurer la robustesse de la procdure en prsence du convertisseur. L'application porte sur le dimensionnement d'un moteur aimants permanents de type ?brushless trapzodal" destin la traction d'un scooter lectrique ; l'volution de la structure optimale avec le degr de complexit du module d'analyse est mise en vidence.
Study of H {yields} {gamma}{gamma} decay; Etude de la desintegration du H {yields} {gamma}{gamma}
1992-11-01
The authors study the H {yields}{gamma}{gamma} decay in the Standard model and present the detailed calculation of scattering amplitude of this process involving Feynman diagrams of three points loops. The calculation of these diagrams can be effected in different gauges and involves fermion, gauge boson and phantom loops. The decay width of the process is derived in conclusion.
Etude de la desintegration du H yields gamma gamma. (Study of H yields gamma gamma decay).
The authors study the H (yields)(gamma)(gamma) decay in the Standard model and present the detailed calculation of scattering amplitude of this process involving Feynman diagrams of three points loops. The calculation of these diagrams can be effected in ...
Impacts of afforestation on groundwater resources and quality
Plans to double the proportion of land under forest cover in Ireland by the year 2035 have been initiated. The plan, primarily financially driven, ignores potential environmental impacts of forestry, particularly impacts on groundwater resources and quality. Since groundwater supplies almost 25% of Ireland's total potable water, these impacts are important. Field investigations indicate that afforestation leads to a reduction in runoff by as much as 20%, mainly due to interception of rainfall by forest canopies. Clearfelling has the opposite impact. Implications are that uncoordinated forestry practices can potentially exacerbate flooding. Groundwater recharge is affected by forestry, largely due to greater uptake of soil water by trees and to increased water-holding capacity of forest soils, arising from higher organic contents. Recharge rates under forests can be reduced to one tenth that under grass or heathland. Groundwater quality may be affected by enhanced acidification and nitrification under forests, due partly to scavenging of atmospheric pollutants by forest canopies, and partly to greater deposition of highly acid leaf litter. The slower recharge rates of groundwater under forests lead to significant delays in manifestation of deterioration in groundwater quality. Rsum. Des plans sont l'tude pour doubler la proportion du couvert forestier en Irlande d'ici 2035. Le plan, primitivement dtermin sur une base financire, ignore les impacts environnementaux potentiels de la foresterie, et particulirement les impacts sur les ressources en eau souterraine et leur qualit. Du fait que les eaux souterraines satisfont presque 25% du total de l'eau potable de l'Irlande, ces impacts sont importants. Les tudes de terrain montrent que le reboisement conduit une rduction du ruissellement d'au moins 20%, principalement cause d'une interception de la pluie par le couvert forestier. Les coupes ont un impact contraire. Les implications sont que des pratiques forestires non coordonnes sont susceptibles d'exacerber les crues. La recharge des nappes est affecte par la foresterie, surtout cause de prlvements plus importants de l'eau du sol par les arbres et cause de la capacit accrue des sols forestiers retenir de l'eau, conduisant de plus fortes teneurs en matires organiques. Les taux de recharge sous les forts peuvent tre rduits d'un dixime par rapport la prairie ou la lande. La qualit de l'eau souterraine peut tre affecte par une acidification accrue et par une nitrification sous les forts, provoques pour une part par une fixation des polluants atmosphriques par le couvert forestier et pour une autre part par un dpt plus important d'une litire plus fortement acide. Les taux de recharge plus lente des nappes sous les forts conduisent des retards importants dans la manifestation de la dtrioration de la qualit de l'eau souterraine. Resumen. Se han iniciado los planes para duplicar la proporcin de terrenos reforestados en Irlanda hacia el ao 2035. El plan, impulsado por fines econmicos, ignora los impactos potenciales medioambientales de la silvicultura, y, en particular, los impactos a los recursos de aguas subterrneas y a su calidad. Puesto que el 25 % del agua potable en Irlanda es suministrada por medio de aguas subterrneas, dichos impactos son importantes. Las investigaciones de campo indican que la reforestacin lleva a una reduccin de la escorrenta de hasta un 20 %, fundamentalmente por la interceptacin de la lluvia en las copas de los rboles, mientras que la deforestacin tiene el impacto opuesto. Las implicaciones son tales que las prcticas forestales descoordinadas pueden aumentar enormemente el riesgo de inundaciones. Tambin la recarga a los acuferos se ve afectada por la reforestacin, debido, sobre todo, al uso del agua del suelo por los rboles y a la mayor capacidad de retencin de los suelos en zonas boscosas, al disponer de ms materia orgnica. Las tasas de recarga en zonas boscosas pueden verse reducidas al 10 % de las estimadas en campos de hierba o brezales. La calidad de las aguas subterrneas en zonas boscosas puede verse afectada por procesos de acidificacin y nitrificacin adicionales, causados por la retencin de contaminantes atmosfricos en las copas de los rboles, y, en parte, por la acumulacin de hojas enormemente cidas en descomposicin. El hecho de que la tasa de recarga sea inferior en zonas boscosas causa un retardo en la deteccin de fenmenos de deterioro de la calidad de las aguas subterrneas.
1961-06-15
1. This original study firstly defines the problem of the adjustment of the coolant flow rate in a reactor channel as a function of the corresponding heat transfer equations and of the local and temporal neutron flux. The necessity of such an adjustment is pointed out and the modifying parameters are studied. An adjustment study using the envelope of the possible flux curves is developed. A short study on the technology and the economical advantage of this adjustment is presented. Some measurements, made on G-1 and G-2, show the precision one can obtain from adjustment apparatus itself as well as from the complete reactor adjustment system. 2. Evolution of nuclear properties of fuel in an heterogeneous thermal reactor. In the first port of this paper, the phenomena of fuel evolution have been mainly pointed out. Now a bibliographical study more qualitatively than quantitatively has been done. This survey specifies the present theories and relates to a real effective cross section and also yields to the bases of such a nuclear calculation. (author) [French] 1. Cette etude originale definit d'abord le probleme du reglage du debit de refrigerant dans un canal de reacteur en fonction de la formulation du calcul des performances thermodynamiques de ce canal et des variations du flux neutronique dans l'espace et le temps. La necessite du reglage est ensuite mise en evidence et les parametres le modifiant sont etudies. Une methode de reglage, basee sur l'emploi d 'une courbe enveloppe des courbes de flux possibles, est donnee. Une breve etude de la technologie et des incidences economiques du reglage est presentee. Des mesures effectuees sur les reacteurs G-1 et G-2 montrent la precision que l'on peut attendre des dispositifs de reglage comme du reglage d'ensemble du reacteur lui-meme. 2. Evolution des proprietes nucleaires du combustible dans un reacteur heterogene a neutrons thermiques. Les phenomenes d'evolution du combustible tiennent une place importante dans l'etude precedente. Une etude bibliographique plus qualitative que quantitative a donc ete effectuee sur ce point. Cet examen expose les theories actuelles, se refere en particulier a l'emploi d'une section efficace dite effective et fournit ainsi les principes d'un tel calcul neutronique. (auteur)
1957-07-01
The thermal utilisation factor of the lattice of the reactor G1 has been measured by applying the autoradiographic technique to thin detectors irradiated in the cell. The experimental apparatus is described, and the results compared with those obtained by calculation based on various formulae. The results of the study of the thermal flux distribution in a cell containing a thorium rod of the same diameter as the uranium rods in the lattice are also given. The precision of the measurements is discussed. Value found: f diameter 26 = 0.8949 {+-} 0,005. (author) [French] Le facteur d'utilisation thermique du reseau du reacteur G1 a ete mesure en appliquant la technique de l'autoradiographie a des detecteurs minces irradies dans la cellule. Les dispositifs experimentaux sont decrits et les resultats sont compares a ceux obtenus par le calcul a partir de diverses formules. Les resultats de l'etude de la distribution du flux thermique dans une cellule contenant une barre de thorium de meme diametre que les barres d'uranium du reseau sont egalement indiques. La precision des mesures est discutee. Valeur trouvee: f diametre 26 = 0,8949 {+-} 0,005. (author)
Incentives for the use of depleted uranium alloys as transport cask containment structure
1993-01-01
Radioactive material transport casks use either lead or depleted uranium (DU) as gamma-ray shielding material. Stainless steel is conventionally used for structural containment. If a DU alloy had sufficient properties to guarantee resistance to failure during both normal use and accident conditions to serve the dual-role of shielding and containment, the use of other structural materials (i.e., stainless steel) could be reduced. (It is recognized that lead can play no structural role.) Significant reductions in cask weight and dimensions could then be achieved perhaps allowing an increase in payload. The mechanical response of depleted uranium has previously not been included in calculations intended to show that DU-shielded transport casks will maintain their containment function during all conditions. This paper describes a two-part study of depleted uranium alloys: First, the mechanical behavior of DU alloys was determined in order to extend the limited set of mechanical properties reported in the literature (Eckelmeyer, 1991). The mechanical properties measured include the tensile behavior the impact energy. Fracture toughness testing was also performed to determine the sensitivity of DU alloys to brittle fracture. Fracture toughness is the inherent material property which quantifies the fracture resistance of a material. Tensile strength and ductility are significant in terms of other failure modes, however, as will be discussed. These mechanical properties were then input into finite element calculations of cask response to loading conditions to quantify the potential for claiming structural credit for DU. (The term 'structural credit' describes whether a material has adequate properties to allow it to assume a positive role in withstanding structural loadings.) (J.P.N.).
1969-07-01
A new method is proposed for the computation of the dose delivered to any level of the gastrointestinal tract after ingestion of radioactive substances. The same method is used as that proposed by ICRP. The concentration of the radionuclide during the progression of the meal is the central concept of this model. A graph relates the MPC with the radioactive half life of the radionuclide and with any level of the gastrointestinal tract of adults.Soluble and insoluble radionuclides are considered. The case of daughter products is discussed in the Appendix. (author) [French] Une methode nouvelle permet le calcul de la dose delivree a un niveau quelconque du tractus gastrointestinal apres ingestion de substances radioactives. Elle utilise d une part la technique de calcul proposee par l'ICRP et de l'autre la notion de concentration du radionuclide au cours de la progression du repas. Un graphique simple met en relation la valeur de la concentration maximale admissible avec la periode radioactive du radionuclide et le niveau considere du tractus gastrointestinal de l'adulte. Le cas d'un radionuclide soluble et celui d'un radionuclide insoluble sont envisages. Un appendice traite le cas des filiations. (auteur)
An analysis of uranium dispersal and health effects using a Gulf War case study.
The study described in this report used mathematical modeling to estimate health risks from exposure to depleted uranium (DU) during the 1991 Gulf War for both U.S. troops and nearby Iraqi civilians. The analysis found that the risks of DU-induced leukemia or birth defects are far too small to result in an observable increase in these health effects among exposed veterans or Iraqi civilians. Only a few veterans in vehicles accidentally struck by U.S. DU munitions are predicted to have inhaled sufficient quantities of DU particulate to incur any significant health risk (i.e., the possibility of temporary kidney damage from the chemical toxicity of uranium and about a 1% chance of fatal lung cancer). The health risk to all downwind civilians is predicted to be extremely small. Recommendations for monitoring are made for certain exposed groups. Although the study found fairly large calculational uncertainties, the models developed and used are generally valid. The analysis was also used to assess potential uranium health hazards for workers in the weapons complex. No illnesses are projected for uranium workers following standard guidelines; nonetheless, some research suggests that more conservative guidelines should be considered.
An analysis of uranium dispersal and health effects using a Gulf War case study.
The study described in this report used mathematical modeling to estimate health risks from exposure to depleted uranium (DU) during the 1991 Gulf War for both U.S. troops and nearby Iraqi civilians. The analysis found that the risks of DU-induced leukemia or birth defects are far too small to result in an observable increase in these health effects among exposed veterans or Iraqi civilians. Only a few veterans in vehicles accidentally struck by U.S. DU munitions are predicted to have inhaled sufficient quantities of DU particulate to incur any significant health risk (i.e., the possibility of temporary kidney damage from the chemical toxicity of uranium and about a 1% chance of fatal lung cancer). The health risk to all downwind civilians is predicted to be extremely small. Recommendations for monitoring are made for certain exposed groups. Although the study found fairly large calculational uncertainties, the models developed and used are generally valid. The analysis was also used to assess potential uranium health hazards for workers in the weapons complex. No illnesses are projected for uranium workers following standard guidelines; nonetheless, some research suggests that more conservative guidelines should be considered.
An analysis of uranium dispersal and health effects using a Gulf War case study.
2005-07-01
The study described in this report used mathematical modeling to estimate health risks from exposure to depleted uranium (DU) during the 1991 Gulf War for both U.S. troops and nearby Iraqi civilians. The analysis found that the risks of DU-induced leukemia or birth defects are far too small to result in an observable increase in these health effects among exposed veterans or Iraqi civilians. Only a few veterans in vehicles accidentally struck by U.S. DU munitions are predicted to have inhaled sufficient quantities of DU particulate to incur any significant health risk (i.e., the possibility of temporary kidney damage from the chemical toxicity of uranium and about a 1% chance of fatal lung cancer). The health risk to all downwind civilians is predicted to be extremely small. Recommendations for monitoring are made for certain exposed groups. Although the study found fairly large calculational uncertainties, the models developed and used are generally valid. The analysis was also used to assess potential uranium health hazards for workers in the weapons complex. No illnesses are projected for uranium workers following standard guidelines; nonetheless, some research suggests that more conservative guidelines should be considered.
1995-12-01
Neptune is a controller for space heating systems including a maximum of three heating plants and four secondary networks; an intermittency load programming is included in the control strategy and the calculation of heating restart times for a secondary network is presented, based on the development and on-line identification of building thermal behaviour models. The calculation method has been verified within a simulated structure and with real data recorded in a school building
1958-07-01
The authors describe relative cross-section measurements of fission of the isotopes of uranium and plutonium (more particularly {sup 235}U, {sup 238}U, {sup 239}Pu), with emission of long range particles, under the action of neutrons of various energies: thermal neutrons, pile neutrons, neutrons produced with the Van de Graaff accelerator by reaction of protons on tritium. The measurements are carried out: 1) with the aid of photographic plates, by submitting to the action of the neutrons a layer of fissile material coupled with an Ilford nuclear emulsion of 200 microns; a tin sheet laying between the plate and the layer stops the {alpha} particles and the fission fragments. By an appropriate development the tracks of the long range particles can be distinguished in the emulsion, from the tracks of the recoil protons resulting of fission neutrons, or of the last primary neutrons. For neutrons of energy under 1 MeV, the compared frequency of the tracks of long range particles and of the recoils caused by the fission neutrons gives a measurement of the fission cross-section with emission of long range particles relative to the product of the fission cross-section by the mean number of neutrons emitted by fission. For neutrons of higher energy, one measures only the frequency of the tracks of long range particles, comparatively with the flux of primary neutrons. Some precautions are taken to eliminate the action of thermal neutrons in the measurements with fast neutrons. 2) with the aid of a system of ionization chamber and proportional counter, the rate of coincidence between the impulsions caused by the long range particles and the impulsions provided by one of the fission fragments is measured comparatively with the counting rate of fission fragme (author) [French] Les auteurs decrivent des mesures relatives a la section efficace de fission des isotopes de l'uranium et du plutonium (notamment {sup 235}U, {sup 238}U, {sup 239}Pu) avec emission de particules de long parcours, sous l'action de neutrons de diverses energies: neutrons thermiques, neutrons de pile, neutrons produits avec l'accelerateur Van de Graaff par la reaction des protons sur le tritium. Les mesures sont effectuees: 1) a l'aide de plaques photographiques, en soumettant a l'action des neutrons une couche de matiere fissile, accolee contre une emulsion nucleaire Ilford de 100 microns; une feuille d'etain appliquee entre la plaque et la couche arrete les {alpha} et les fragments de fission. On distingue dans l'emulsion par un developpement approprie les trajectoires de particules de long parcours des trajectoires de protons de recul provenant soit des neutrons de fission, soit des neutrons primaires rapides. La frequence comparee des trajectoires des particules de long parcours et des reculs dus aux neutrons de fission fournit une mesure de la section efficace de fission avec emission de particules de long parcours relativement au produit de la section efficace de fission par le nombre moyen de neutrons emis par fission. Des precautions sont prises peur eliminer le role des neutrons thermiques dans les mesures par neutrons rapides. 2) a l'aide d'un systeme de chambre d'ionisation et compteur proportionnel, on mesure le taux de coincidence entre les impulsions produites par la particule de long parcours et celles produites par un des fragments de fission, relativement au taux de comptage des fragments de fission. (auteur)
1992-01-01
Chromium-51 ethylene diamine tetra-acetic acid ({sup 51}Cr-EDTA) total plasma clearance was evaluated using a multi-sample method (i.e. 12 blood samples) as the reference compared with several simplified methods which necessitated only one or few blood samples. The following 5 methods were evaluated: Terminal slope-intercept method with 3 blood samples, simplified method of Broechner-Mortensen and 3 single-sample methods (Constable, Christensen and Groth, Tauxe). Linear regression analysis was performed. Standard error of estimate, bias and imprecision of different methods were evaluated. For {sup 51}Cr-EDTA total plasma clearance greater than 30 ml.min{sup -1}, the results which most approximated the reference source were obtained by the Christensen and Groth method at a sampling time of 300 min (inaccuracy of 4.9%). For clearances between 10 and 30 ml.min{sup -1}, single-sample methods failed to give reliable results. Terminal slope-intercept and Broechner-Mortensen methods were better, with inaccuracies of 17.7% and 16.9%, respectively. Although sampling times at 180, 240 and 300 min are time-consuming for patients, {sup 51}Cr-EDTA total plasma clearance can be accurately calculated for values greater than 10 ml.min{sup -1} using the Broechner-Mortensen method. In patients with clearance greater than 30 ml.min{sup -1}, single-sample techniques provide a good alternative to the multi-sample method; the choice of the method to be used depends on the degree of accuracy required. (orig.).
1964-07-01
1 - The position of fast neutron reactors in the French nuclear energy program. In developing a program based on natural uranium, France will have an important stock of plutonium rich in higher isotopes. The existence of this plutonium and of the depleted uranium arising from the same reactors, has, as a logical consequence, the use of both in fast neutron reactors. Justified by this short term interest, the achievement of fast neutron reactors does, moreover, provide for a future necessity. 2 - Description of a fast neutron central power station of 1000 MWe. We indicate the characteristics of a future fast neutron central power station, plutonium fuelled, and sodium cooled. However uncertain these characteristics may be, they constitute a necessary guide in the orientation of our work. 3 - Studies carried out up to the present time. We give an outline of those studies, often very preliminary, which have given the characteristics cited above. The principal technical areas taken up are the following: - Neutronics (critical masses, breeding ratios, enrichments, flattening of the neutron flux, coefficients of reactivity, reactivity changes as a function of irradiation). - Dynamics, control, and safety. - Technology (design of the core and vessel, of the sodium system, and of the fuel handling mechanisms). These technical studies are complemented by economic considerations. The choice of the optimum characteristics is related to the existence of power production programs, and, in these programs, to the existence of plutonium producing thermal reactors. It is shown how, in this context, the existence of plutonium should be taken into account, and, in addition which mechanisms relate the economics of this plutonium to the choice of the most important parameters of the breeder reactors. 4 - Prototype reactor. The interest in an intermediate stage consisting of a reactor of a power level of about 80 MWe is justified. Its essential characteristics are briefly presented. (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 intermediaire constituee par un reacteur d'une puissance voisine de 80 MWel. Ses caracteristiques essentielles sont brievement presentees. (auteurs)
Un nouveau vaccin conjugué contre le méningocoque: Que devraient faire et savoir les médecins?
Un vaccin conjugué quadrivalent contre le méningocoque de séro-groupes A, C, Y et W135 (MCV4 [Menactra, sanofi pasteur, Canada]) a été lancé au Canada en 2007 pour les personnes de deux ans ou plus. Le MCV4 ajoute trois sérogroupes aux vaccins conjugués contre le méningocoque de sérogroupe C, utilisé depuis plusieurs années. Les taux de méningococcies invasives du sérogroupe C ont fléchi depuis dix ans grâce au vaccin conjugué contre le méningocoque de séro-groupe C. Cependant, l’incidence d’infection causée par les séro-groupes A, B, Y et W135 n’a pas tellement changé. Le vaccin MCV4 induit la production d’anticorps protecteurs contre les sérogroupes A, C, Y et W135 chez les adultes et les enfants de plus de deux ans. Les effets indésirables graves du vaccin MCV4 sont peu fréquents. Étant donné l’efficacité des vaccins conjugués contre le méningocoque de sérogroupe C administrés aux jeunes nourrissons et le nombre élevé de méningococcies du sérogroupe C au Canada par le passé, les médecins devraient favoriser et promouvoir les programmes de vaccination sub-ventionnés par le gouvernement entrepris dès l’âge de deux mois. Le vaccin MCV4 devrait également être administré aux enfants de deux ans plus vulnérables à une méningococcie. On peut également envisager de l’administrer aux enfants positifs au VIH de deux ans ou plus. Il faut offrir une dose de rappel du vaccin MCV4 ou d’un vaccin conjugué contre le méningocoque de sérogroupe C à tous les adolescents vers l’âge de 12 ans. D’ordinaire, ces vaccins sont sécuritaires et bien tolérés.
1969-07-01
The results described in this study are relative to the artificial radioactivity of such elements as zirconium-95, niobium-95, ruthenium-103, ruthenium-106, cerium-141, cerium-144 and praseodymium-144 which were present in the atmospheric fallout between 1962 and 1964, and their incidence in superficial marine waters. Various physical, chemical or biological processes are studied by a high sensitivity gamma ray spectrometry technic, using those radioelements as 'tracers'. The change of state in sea water of an important fraction (about 50 per cent) of the radioactive particles going into the soluble phase - this phenomenon was not expected for those radioelements - controls the processes of accumulation in the planktonic biomass and the diffusion towards deeper waters. On the other hand, an 'in situ' spectrometry method is described. It enables the direct measurement in the sea of very low concentrations of some gamma ray emitters. The application of this method has made possible to carry out numerous observations in the surface waters of the Western Mediterranean sea and in the Bay of Biscay. It is shown that the mixing depth is closely connected to the depth of the thermocline. An accumulation process at this level is observed. The diffusion coefficients are similar to the thermal turbulent coefficient. The existence during several months of 'compartments' is established for the surface waters of the Bay of Biscay. From the establishment of the budget of fall-out, a comparative study shows that the rate of radioactive fallout on the maritime zone considered is always two to three times higher than on the neighbouring continental regions. Several explanations of this phenomenon are discussed. (author) [French] Les resultats decrits dans cette etude concernent la radioactivite artificielle sous forme de zirconium-95, niobium-95, ruthenium-103, ruthenium-106, cerium-141, cerium-144 et praseodyme-144 apportee par la retombee atmospherique entre 1962 et 1964 et les incidences de cette retombee dans les eaux marines superficielles. Considerant les radioelements etudies comme des 'traceurs' dans le milieu marin, divers processus physiques, chimiques ou biologiques ont ete etudies par spectrometrie gamma a haute sensibilite. Le passage en phase soluble dans l'eau de mer d'une fraction importante (environ 50 pour cent) de l'activite liee aux poussieres radioactives, phenomene qui n'etait pas previsible pour les radioelements etudies, gouverne les processus d'accumulation dans la biomasse planctonique et la diffusion vers les eaux plus profondes. Par ailleurs, une methode de spectrometrie 'in situ' permettant de mesurer directement dans la mer de tres faibles concentrations en certains radionuclides emetteurs gamma est decrite. L'application de cette methode a permis de nombreuses observations dans les eaux de surface de la Mediterranee occidentale et du Golfe de Gascogne. On montre quo la profondeur de melange est etroitement liee a celle de la thermocline. Un processus d'accumulation au niveau de celle-ci est constate. Les coefficients de diffusion sont voisins du coefficient de diffusion thermique turbulente. L'existence de compartiments qui subsistent pendant plusieurs mois dans la masse des eaux de surface du Golfe de Gascogne est mise en evidence. Grace aux bilans effectues, une etude comparative montre que le taux de retombees radioactives sur les surfaces maritimes est toujours deux a trois fois superieur a celui sur les regions continentales voisines. Diverses explications de ce phenomene sont discutees. (auteur)
2002-09-01
Dear Sir, Eric Hamilton takes the Royal Society and myself to task for investigating the health hazards of depleted uranium munitions. In his view the matter appears to be clear. Exposures to uranium have been studied extensively for decades in the nuclear industry and there is little evidence of adverse health consequences. Exposures to DU on the battlefield are therefore unlikely to have health consequences and setting up an independent working group to look at the scientific issues only suggests there are doubts about the science, and leads to mistrust and confusion in the minds of the public. This type of robust approach to addressing the risks of exposure to radioactive materials, and of attempting to assuage the concerns of veterans exposed to DU during the Gulf War, may have worked in the past but it doesn't work today. The Royal Society is accused of having failed to address the main issue, which Hamilton considers to be the failure to implement well established and validated monitoring procedures at the time DU weapons were deployed, so that intakes and risks could have been calculated. This is a curious perspective as, from the outset, the remit of the Royal Society working group was to provide an independent view of the science, rather than the deficiencies in procedures, in response to public concerns and to the very different pronouncements about the dangers to health and the environment arising from the deployment of over 300 tonnes of DU munitions in the Gulf War. Some of the comments in the Royal Society reports and the editorial are considered to be questionable or not acceptable. It is not clear which particular aspects cause offence. One aspect appears to be the claim that DU measurements are difficult, where Hamilton appears to misunderstand the nature of the problem of quantifying exposures to DU. Of course uranium concentrations and isotope ratios are routinely measured in the nuclear industry and in geochemical laboratories, but the problem is not one of analysing DU debris' but of looking for, and quantifying, the minute amounts of DU that are being excreted in the urine of veterans who were exposed to DU aerosols during the Gulf War. Reliably measuring uranium isotopes (particularly the very small percentage of {sup 235}U) in urine that contains a few nanograms of total uranium per litre is a challenge. Hamilton doubts that epidemiological studies of veterans will be useful, and comments that radioactive exposures or releases by the nuclear industry have not impaired the health of the population or workforce, and that uranium has never been identified as an element of concern. Epidemiological studies do indeed provide little evidence that exposure to uranium in industrial settings is associated with excess overall mortality, or with increased mortality from cancers or kidney disease. However, the exposures to insoluble DU oxides on the battlefield may be significantly different (in solubility, particle size, amount) from typical exposures in industry, and the existing epidemiological studies of worker cohorts are not particularly sensitive, and I disagree that epidemiological studies are of no value in the context of exposures to DU on the battlefield. Certainly there were multiple exposures to toxic, or potentially toxic, agents in the Gulf War, but tests that measure the amounts of DU in the urine of soldiers have been promised to veterans and, if these identify a group of soldiers who received substantial intakes, case-control studies should allow a sensitive evaluation of any link between exposure to DU and ill health. Hamilton is also concerned that the issue of 'hot particles' is not examined in sufficient depth but in the same sentence he says that data are lacking upon which a judgement can be made. In any case, it is very unclear why 'hot particles' should have been discussed in depth. Hamilton himself defines such particles as highly radioactive and potentially hazardous unprocessed, spent-reactor uranium fuel debris', something quite different from the very much less radioactive particles released in DU penetrator impacts. However, the Royal Society reports do flag up the need to re-assess the robustness of current estimates of risks from the inhalation of radioactive particles and CERRIE is currently addressing this question. There is one point made by Hamilton with which I agree. Far more effort should have been made to understand intakes of DU during the Gulf War, and the Royal Society working group has consistently been critical of the lack of data on intakes of DU by soldiers in the Gulf War, and has been pressing the Ministry of Defence to ensure that there is adequate and timely monitoring in any future conflict where DU munitions are deployed. It is only when we have these intake data that we can really evaluate the risks associated with these exposures and the uncertainties associated with these estimates.
1998-12-31
This work studies the seismic behaviour of fast neutrons reactor cores. It consists in analyzing the tests made on the models Rapsodie and Symphony by using the calculation code Castem 2000. Te difficulty is in the description of connections of the system and the effects of the fluid (calculation in water). The results for the programme Rapsodie are near the experimental results. For the programme Symphony, the calculations in air have allowed to represent the behaviour of fuel assemblies in a satisfying way. It is still to analyze the tests Symphony in water. (N.C.)
2009-11-15
We calculate the QED and QCD radiative corrections to the charged lepton energy distributions in the dominant semileptonic decays of the top quark t{yields}bW{sup +}{yields}b(l{sup +}{nu}{sub l}) (l=e,{mu},{tau}) in the standard model (SM), and for the decay t{yields}bH{sup +}{yields}b({tau}{sup +}{nu}{sub {tau}}) in an extension of the SM having a charged Higgs boson H{sup {+-}} with m{sub H}{sup {+-}}{sup <}m{sub t}-m{sub b}. The QCD corrections are calculated in the leading and next-to-leading logarithmic approximations, but the QED corrections are considered in the leading logarithmic approximation only. These corrections are numerically important for precisely testing the universality of the charged current weak interactions in t-quark decays. As the {tau}{sup +} leptons arising from the decays W{sup +}{yields}{tau}{sup +}{nu}{sub {tau}} and H{sup +}{yields}{tau}{sup +}{nu}{sub {tau}} are predominantly left- and right-polarised, respectively, influencing the energy distributions of the decay products in the subsequent decays of the {tau}{sup +}, we work out the effect of the radiative corrections on such distributions in the dominant (one-charged prong) decay channels {tau}{sup +}{yields}{pi}{sup +} anti {nu}{sub {tau}},{rho}{sup +} anti {nu}{sub {tau}},a{sub 1}{sup +} anti {nu}{sub {tau}} and l{sup +}{nu}{sub l} anti {nu}{sub {tau}}. The inclusive {pi}{sup +} energy spectra in the decay chains t{yields}b(W{sup +},H{sup +}){yields}b({tau}{sup +}{nu}{sub {tau}}){yields}b({pi}{sup +} anti {nu}{sub {tau}}{nu}{sub {tau}}+X) are calculated, which can help in searching for the induced H{sup {+-}} effects at the Tevatron and the LHC. (orig.)
1998-06-19
In order to improve and to validate the neutronic calculation schemes, perfecting integral measurements of neutronic parameters is necessary. This thesis focuses on the conception, the improvement and the development of neutronic reaction rates measurements, and aims at building a base of standard techniques. Two subjects are discussed. The first one deals with direct measurements by fission chambers. A short presentation of the different usual techniques is given. Then, those last ones are applied through the example of doubling time measurements on the EOLE facility during the MISTRAL 1 experimental programme. Two calibration devices of fission chambers are developed: a thermal column located in the central part of the MINERVE facility, and a calibration cell using a pulsed high flux neutron generator and based on the discrimination of the energy of the neutrons with a time-of-flight method. This second device will soon allow to measure the mass of fission chambers with a precision of about 1 %. Finally, the necessity of those calibrations will be shown through spectral indices measurements in core MISTRAL 1 (UO{sub 2}) and MISTRAL 2 (MOX) of the EOLE facility. In each case, the associated calculation schemes, performed using the Monte Carlo MCNP code with the ENDF-BV library, will be validated. Concerning the second one, the goal is to develop a method for measuring the modified conversion ratio of {sup 238}U (defined as the ratio of {sup 238}U capture rate to total fission rate) by gamma-ray spectrometry of fuel rods. Within the framework of the MISTRAL 1 and MISTRAL 2 programmes, the measurement device, the experimental results and the spectrometer calibration are described. Furthermore, the MCNP calculations of neutron self-shielding and gamma self-absorption are validated. It is finally shown that measurement uncertainties are better than 1 %. The extension of this technique to future modified conversion ratio measurements for {sup 242}Pu (on MOX rods) and {sup 232}Th (on Thorium rods) is also detailed and will be interesting for both studies on the accelerator driven systems and minor actinides transmutation. (author) 68 refs.
1966-07-01
- The e.m.f. of the cell: Ag | AgCl(X).KCl-LiCl(eut) | Cl{sub 2} | C is measured for mole fractions of between 10{sup -4} and 1, and for temperatures of between 400 and 500 deg. C. From the function E = F (X,T) are deduced: 1 - The partial molar entropy of silver chloride. This confirms the relationship for regular solutions: {delta}S-bar = - R log{sub e} X; 2 - The partial molar enthalpy of silver chloride {delta}H-bar. This value is practically constant with temperature and obeys a parabolic law as a function of the concentration; 3 - The activities of the solute and of the solvent. By assuming that a short-distance order exists in the molten mixture, one arrives at the preceding results, by calculation. In particular an expression is deduced for the activity coefficient which is valid for all concentrations and temperatures compatible with the system liquid state. (author) [French] On mesure la f.e.m. de la cellule: Ag |AgCl(X).KCl-LiCl(eut)| CL{sub 2} | C pour des fractions molaires comprises entre 10{sup -4} et 1 et des temperatures T variant de 400 a 500 deg. C. A partir de la fonction E = F (X,T) on deduit: 1 - L'entropie molaire partielle du chlorure d'argent. Celle-ci verifie la relation des solutions regulieres: {delta}S-bar = - R. Ln X; 2 - L'enthalpie molaire partielle du chlorure d'argent {delta}H-bar. Cette grandeur ne varie pratiquement pas avec la temperature et suit une loi parabolique en fonction de la concentration. 3 - Les activites du solute et du solvant. En postulant l'existence d'un ordre a courte distance dans le melange fondu, on retrouve, par le calcul, les resultats precedents. En particulier, on etablit une expression du coefficient d'activite valable pour toutes concentrations et temperatures compatibles avec l'etat liquide du systeme. (auteur)
Le sujet de cette these concerne la problematique de fonctionnement et de selection des appareils a mise et remise a roue a godets dans les systemes de manutention des materiaux en vrac a grande echelle. Premierement, une etude bibliographique a ete effectuee. En se basant sur les lacunes dans les connaissances du domaine analyse, les objectifs de la recherche ont ete definis. Ils sont divises en trois parties: (1) Developper une methodologie du calcul de la capacite des machines en operation de reprise refletant les relations entre les caracteristiques de l'equipement et les parametres de son environnement de travail. (2) Developper un critere d'evaluation du niveau technique de ces machines. (3) Definir les relations entre la machine et les parametres du materiau empile lors de l'operation du stockage. La premiere etape de recherche consiste en la creation d'une base de donnees concernant les parametres de construction et de travail de ces machines. Les donnees des fiches techniques sont souvent presentees de facon variee et incomplete et la recherche a ete orientee vers l'unifonnisation des donnees. Dans la seconde phase, une fonction de vitesse de balayage de la fleche est definie. Elle est basee sur la forme particuliere du materiau empile en stock et la geometrie de travail des machines. Cette fonction sert comme base pour l'elaboration d'une methodologie precise de calcul de la capacite de ces appareils en operation de reprise. Le resultat final rencontre cet objectif. La troisieme partie concerne lelaboration d'un modele d'evaluation du niveau technique de ces machines en se basant sur une analyse statistique et correlationnelle de leurs parametres techniques se trouvant dans la base de donnees. Ces resultats, jumeles avec les parametres economiques (cout de possession et d'operation), servent de base pour la formulation d'un coefficient de niveau technique. Dans la demiere etape, un modele definissant l'operation de ces appareils en stockage a ete developpe. En fonction du mode de stockage, les relations entre les parametres geometriques d'une section du materiau empile et les parametres operationnels ont ete definies. L'applicabilite du modele a ete validee au port de Port Cartier.
Evaluation of the French Haut Taux de Combustion (HTC) Critical Experiment Data
2008-01-01
In the 1980s, a series of critical experiments referred to as the Haut Taux de Combustion (HTC) experiments was conducted by the Institut de Radioprotection et de Surete Nucleaire (IRSN) at the experimental criticality facility in Valduc, France. The plutonium-to- uranium ratio and the isotopic compositions of both the uranium and plutonium used in the simulated fuel rods were designed to be similar to what would be found in a typical pressurized-water reactor fuel assembly that initially had an enrichment of 4.5 wt% 235U and was burned to 37,500 MWd/MTU. The fuel material also includes 241Am, which is present due to the decay of 241Pu. The HTC experiments include configurations designed to simulate fuel handling activities, pool storage, and transport in casks constructed of thick lead or steel. Rights of use for the HTC experiment data ...
Radiological Risk Assessment of Capstone Depleted Uranium Aerosols
Assessment of the health risk from exposure to aerosols of depleted uranium (DU) is an important outcome of the Capstone aerosol studies that established exposure ranges to personnel in armored combat vehicles perforated by DU munitions. Although the radiation exposure from DU is low, there is concern that DU deposited in the body may increase cancer rates. Radiation doses to various organs of the body resulting from the inhalation of DU aerosols measured in the Capstone studies were calculated using International Commission on Radiological Protection (ICRP) models. Organs and tissues with the highest calculated committed equivalent 50-yr doses were lung and extrathoracic tissues (nose and nasal passages, pharynx, larynx, mouth and thoracic lymph nodes). Doses to the bone surface and kidney were about 5 to 10% of the doses to the extrathoracic tissues. The methodologies of the ICRP International Steering Committee on Radiation Standards (ISCORS) were used for determining the whole body cancer risk. Organ-specific risks were estimated using ICRP and U.S. Environmental Protection Agency (EPA) methodologies. Risks for crewmembers and first responders were determined for selected scenarios based on the time interval of exposure and for vehicle and armor type. The lung was the organ with the highest cancer mortality risk, accounting for about 97% of the risks summed from all organs. The highest mean lifetime risk for lung cancer for the scenario with the longest exposure time interval (2 h) was 0.42%. This risk is low compared with the natural or background risk of 7.35%. These risks can be significantly reduced by using an existing ventilation system (if operable) and by reducing personnel time in the vehicle immediately after perforation.
1966-03-01
Part A and B: Since a radio-nuclide of short half-life is characterized essentially by the decrease in its activity even while it is being measured, the report begins by recalling the basic relationships linking the half-life the counting time, the counting rate and the number of particles recorded. The second part is devoted to the problem of corrections for counting losses due to the idle period of multichannel analyzers. Exact correction formulae have been drawn up for the case where the short half-life radionuclide is pure or contains only a long half-life radio-nuclide. By comparison, charts have been drawn up showing the approximations given by the so-called 'active time' counting and by the counting involving the real time associated with a measurement of the overall idle period, this latter method proving to be more valid than the former. A method is given for reducing the case of a complex mixture to that of a two-component mixture. Part C: The problems connected with the qualitative and quantitative analysis of the decay curves of a mixture of radioactive sources of which one at least has a short half-life are presented. A mathematical description is given of six basic processes for which some elements of Fortran programs are proposed. Two supplementary programs are drawn up for giving an overall treatment of problems of dosage in activation analysis: one on the basis of a simultaneous irradiation of the sample and of one or several known samples, the other with separate irradiation of the unknown and known samples, a dosimeter (activation, or external) being used for normalizing the irradiation flux conditions. (author) [French] Parties A et B: Un radionucleide de periode courte etant defini specialement par la decroissance de son activite pendant la duree meme du comptage, on rappelle en premiere partie de ce rapport les relations fondamentales qui lient periode, temps de comptage, taux de comptage et nombre d'impulsions enregistrees. La seconde partie est consacree au probleme des corrections de pertes au comptage dues au temps mort des analyseurs multicanaux. On a etabli les formules de correction exactes lorsque le radionucleide de periode courte est pur ou seulement accompagne d'un radionucleide de periode longue. Par comparaison on a trace sous forme d'abaques les approximations fournies par le comptage dit 'en temps actif' et par un mode de comptage en temps reel associe a la mesure du temps mort global, ce second procede se revelant plus valable que le premier. Dans le cas d'un melange complexe, on donne le moyen de le ramener au probleme a deux constituants. Partie C: On presente les problemes que pose l'analyse qualitative et quantitative des courbes de decroissance d'un melange de sources radioactives dont au moins une de periode courte. Six procedes fondamentaux sont decrits mathematiquement pour lesquels sont proposes des elements de programmes fortran. Deux programmes supplementaires sont construits pour traiter globalement des problemes de dosages en analyse par activation: l'un base sur l'irradiation simultanee d'un echantillon et d'un ou plusieurs temoins; l'autre sur l'irradiation separee de l'echantillon et du temoin, un dosimetre (par activation ou exterieur) servant a normaliser les conditions de flux d'irradiation.
1961-07-01
The present report gives the actual point of studies on vitrification of concentrated solutions of fission products. An active cell, giving glasses in crucibles, permitted to study various glass compositions. The leaching rate from the glass raises 1 to 2 10{sup -7} g of glass/cm{sup 2}/day. Activity loss by volatility during vitrification remains weak and often below 0.1 per cent of total activity. Off gas cleaning is made easier by presence of filter which is compound of granules including iron oxide. After saturation the content of this filter can be melt. Moreover different processes are in experimentation for a more important production. Daily 72 liters of solution containing tracer activity are treated in a continuous calcination and vitrification plant. The loss in {sup 106}Ru is still important and a modification of installation has been necessary. A pot vitrification plant is in study. In order to reduce cost of processing the possibility to pour glass after melting is actuality in study. A production set of very active glass is also in project. (authors) [French] Le present rapport fait le point des etudes menees sur la vitrification des solutions concentrees de produits de fission. Une installation active, produisant des verres en creusets, a permis d'etudier plusieurs compositions de verres. Le taux de perte d'activite par lixiviation a l'eau atteint 1 a 2 10{sup -7} gramme de verre/cm{sup 2}/jour. Les pertes d'activite par volatilite au cours de la cuisson restent faibles et souvent inferieures a 0,1 pour cent de l'activite totale. L'epuration des gaz de cuisson est facilitee par la presence d'un filtre a granules riches en oxyde de fer, dont le contenu peut etre fondu apres saturation. Differentes techniques sont, en outre, en experimentation pour une production plus importante: Une installation de calcination et vitrification continue traite 72 litres par jour de solution contenant une activite traceur. La perte en Ru{sup 106} est encore importante et a necessite des modifications d'appareillage. Une installation de vitrification en 'pot' est etudiee. La possibilite de couler le verre apres fusion est envisagee afin de reduire le prix de revient du procede. Un ensemble de production de blocs de verre tres actifs est en projet. (auteurs)
1965-07-01
The authors define the notions of use values and price of plutonium. They give a 'simplified parametrized model' simulating the equilibrium of the offer and the demand in time, concerning the plutonium and the price deriving from the relative scarcity of this metal, taking into account the technical and economic operating parameters of the various reactors confronted. This model is simple enough to allow direct computations and establish clear relations between the various parameters. The use of the linear programmes method allows on the other hand a wide extension of the model. This report includes three main parts: I - General description of the study (without detailed calculations) II - Mathematical development of the simplified parametrized model and application (the basic data and the results of the calculations are given) III - Appendices (giving the detailed computations of part II). (authors) [French] Les auteurs definissent les notions de valeurs d'usage et de prix du plutonium. Ils donnent un 'modele parametre simplifie' simulant l'equilibre de l'office et de la demande dans le temps concernant le plutonium et le prix qui decoule de la rarete relative de ce metal, compte tenu des parametres techniques et economiques de fonctionnement des divers reacteurs en presence. Ce modele est suffisamment simple pour permettre des calculs manuels et etablir des liaisons claires entre les divers parametres. L'utilisation de la technique des programmes lineaires permet par ailleurs une extension considerable du modele. Cette note comprend trois parties: I - Expose general de l'etude (sans expose du detail des calculs) II - Developpement mathematique du modele parametre simplifie et application (on precise les donnees de base et le resultat des calculs) III - Annexes (donnant le detail des calculs de la partie II). (auteurs)
2001-07-01
As the central point of the design of the intending storing facilities at the surface, concrete, considered as a material, raises new questions with regard to the very severe operating conditions which could be applied during many centuries. Its behavior, specially in accidental phase, is at the basis of the options which will be selected concerning the dimensional calculations of the concrete structures and the choice of the building materials. (authors)
1988-01-01
A high precision sodium pressure sensor with a dynamometric ring has been studied. The sensor constitution, the dynamometric ring calculation, the gauges setting, the measuring circuit and the gauging device are presented. The correction method of in-line temperature effect is given. The calibration error is analyzed
1999-07-01
In order to illustrate the expected variations according to the storage characteristics used for the calculations, a sensitiveness analysis for the storage site of Lodeve is presented by considering the individual and collective doses before and after site refitting. (N.C.)
1990-01-01
After developing a method for analysing rubidium in soil and plant extracts and assuming a similar behaviour of potassium and rubidium, a mixture of the two salt chloride was used: to follow the fate of a potash fertilizer application in a laboratory incubation experiment on different african soils. It was shown that the fertilizer applied was found mainly in the exchangeable compartment and that the reserves in the soil of dilutable potassium -higher than those of exchangeable potassium- can be quantified; to make sure that rubidium chloride is not toxic to the plant in a pot experiment using the palm tree as a test plant and to calculate with the same methods as those used for {sup 15}N the actual coefficient of efficiency of potassium recovery by the plant.
1990-01-01
After developing a method for analysing rubidium in soil and plant extracts and assuming a similar behaviour of potassium and rubidium, a mixture of the two salt chloride was used: to follow the fate of a potash fertilizer application in a laboratory incubation experiment on different african soils. It was shown that the fertilizer applied was found mainly in the exchangeable compartment and that the reserves in the soil of dilutable potassium -higher than those of exchangeable potassium- can be quantified. To make sure that rubidium chloride is not toxic to the plant in a pot experiment using the palm tree as a test plant and to calculate with the same methods as those used for 15N the actual coefficient of efficiency of potassium recovery by the plant
2007-01-01
I discuss some simple aspects of the low-energy physics of a nontrivial scale invariant sector of an effective field theory--physics that cannot be described in terms of particles. I argue that it is important to take seriously the possibility that the unparticle stuff described by such a theory might actually exist in our world. I suggest a scenario in which some details of the production of unparticle stuff can be calculated. I find that in the appropriate low-energy limit, unparticle stuff with scale dimension dU looks like a nonintegral number dU of invisible particles. Thus dramatic evidence for a nontrivial scale invariant sector could show up experimentally in missing energy distributions
1993-01-01
Since nuclear fuel generates a decreasing amount of heat because of the decay of the contained radionuclides, the effects of increased temperatures on the properties of the rock are very important. This thermal cracking experiment was conducted to determine the threshold temperature of thermal cracking in the Lac du Bonnet granite sampled from the Underground Research Laboratory site; calculate the effects of thermal cracking on physical properties that may be important for disposal vault design; and provide data used in evaluating models that estimate microcrack population changes caused by temperature changes. The threshold temperature was determined by monitoring acoustic emissions during slow heating of samples to various temperatures up to 205C. The effect of thermal cracking was determined from measurements of P and S-wave velocities before and after heating.
1966-01-01
In studying the competitiveness of a nuclear merchant vessel, economic assessments in terms of figures were discarded in favor of a simplified model, which gives a clearer idea of the mechanism of the comparison between alternative vessels and the particular influence of each parameter. An expression is formulated for the unit cost per ton carried over a given distance as a function of the variables (speed and deadweight tonnage) and is used to determine the optima for conventional and nuclear vessels. To represent the freight market involved in the optimization studies, and thus in the competitiveness computation, two cases are taken into account: the tonnage to be carried annually is limited, and the tonnage to be carried annually is not limited. In both cases the optima are calculated and compared for a conventional and a nuclear vessel. Competitiveness curves are plotted as a ...
2007-07-15
The study has been carried out by a consortium led by the European Trade Union Confederation (ETUC) and the Social Development Agency (SDA), which includes Syndex, the Wuppertal Institute and ISTAS. It was commissioned by the European Commission, DG environment, as a contribution to improve current understanding of the relationship between climate change and employment. The study was also supported financially by seven public bodies: Ministries of Environment of Belgium, Spain, Finland, Italy, United-Kingdom; ADEME and DIAC in France. The first part of the study examines the potential consequences for employment of global warming in Europe - which has already begun and will continue. The main finding is that even moderate climate change will affect economic activity and employment in Europe, with some regions and economic sectors being particularly vulnerable. Increased warming will be likely to have very damaging consequences. The second half of the report considers the challenge for employment of the transition towards a lower CO2 European economy at the horizon 2030, in four key economic sectors: energy production, transport, steel and cement industries, construction/housing. The study considers a number of scenario for a reduction of 40% in CO2 emissions by the year 2030 and what the effects can be on European employment and skills. Case studies of eleven European countries are also analysed. This report is about Finland. [French] La Finlande est le 5e pays europeen en superficie, avec un total de 338.145 km{sup 2}, pour une population de 5,2 millions d'habitants. Le climat finlandais est le plus froid d'Europe, avec des besoins en chauffage pratiquement toute l'annee et des besoins en eclairage tres importants les mois d'hiver, en raison de la duree tres courte du jour. L'industrie est dominee par l'exploitation forestiere et le papier, ainsi que la metallurgie et la chimie, ces industries etant hautement energie-intensives. Ces elements contribuent a ce que la Finlande ait une des plus importantes intensites energetiques de l'UE, aussi bien par habitant que par unite de PIB produite. L'objectif assigne a la Finlande dans le cadre du protocole de Kyoto est la stabilisation des emissions de GES sur la periode 2008-2012 au niveau de celles de 1990, c'est-adire 70,5 millions de tonnes, tous secteurs confondus. Les hypotheses prises en compte comprennent un taux de croissance annuel moyen de 2,3 % par an entre 2002 et 2012, l'industrie connaissant une croissance legerement superieure a cette moyenne avec 2,4 % par an, les services croissant quant a eux au rythme du PIB et la construction un peu plus lentement. Les emissions dues aux secteurs non soumis a quotas d'emissions sont supposees rester stables. La projection a 2010 en tenant compte des mesures prises pour limiter les rejets de CO2 est estimee a 79,7 MT d'emissions, soit 13 % au-dela du niveau de l'annee de reference. Cette augmentation est due pour l'essentiel aux emissions de CO2 des secteurs energetiques et industriels, qui ont vu leurs emissions augmenter respectivement de 18 % et 64 % depuis 1990. Les mesures prises consistent en: economies d'energie pour 3 a 4 Mt par an, grace a des engagements volontaires et un soutien gouvernemental; promotion des energies renouvelables pour 4 a 5 Mt par an, via une taxation favorable, des aides a l'investissement et des programmes de R et D; une nouvelle unite nucleaire devant permettre une reduction des emissions de CO2 de 10 Mt par an; une taxation de la production de chaleur residentielle en fonction du CO2 emis. Un scenario 'avec mesures additionnelles' aboutit quant a lui a un niveau d'emissions de 71,1 Mt, soit seulement 0,9 % au-dela de l'objectif. La repartition de ces emissions entre les differents secteurs donne: 44,4 Mt pour la production d'energie, en croissance de 1 % par rapport a 1990; 13,2 Mt pour le secteur des transports (+ 5 %); 4,6 Mt pour l'industrie (+ 49 %); 2,3 Mt pour les dechets (- 43 %); 6,6 Mt pour l'agriculture (- 6 %). Le recours aux mecanismes de flexibilite prevus par Kyoto porterait donc sur 0,6 Mt, dans ce scenario. Les quotas attribues pour la periode 2005-2007 s'elevent a 45,5 Mt par an. Pour la periode 2008-2012, les discussions porteraient sur une reduction a 39,5 Mt, avec un effort accru sur la production d'energie. Les objectifs Kyoto de la Finlande peuvent etre consideres comme ambitieux, au vu notamment de la forte croissance des emissions observee dans l'industrie entre 1990 et 2002, du niveau deja plus eleve que la moyenne europeenne d'efficience energetique, et d'une proportion de renouvelables dans le mix energetique deja important. De plus, la tourbe, utilisee dans de nombreuses unites de cogeneration, est consideree comme un combustible fossile et donc comptabilisee comme emettrice de CO2. Enfin la Finlande ne dispose pas de sites de stockage de CO2, les plus proches etant situes en mer du Nord et en mer de Barents.
Thermal Unparticles: A New Form of Energy Density in the Universe
2007-10-29
Unparticle $\\U$ with scaling dimension $d_\\U$ has peculiar thermal properties due to its unique phase space structure. We find that the equation of state parameter $\\omega_\\U$, the ratio of pressure to energy density, is given by $1/(2d_\\U +1)$ providing a new form of energy in our universe. In an expanding universe, the unparticle energy density $\\rho_\\U(T)$ evolves dramatically differently from that for photons. For $d_\\U >1$, even if $\\rho_\\U(T_D)$ at a high decoupling temperature $T_D$ is very small, it is possible to have a large relic density $\\rho_\\U(T^0_\\gamma)$ at present photon temperature $T^0_\\gamma$, large enough to play the role of dark matter. We calculate $T_D$ and $\\rho_\\U(T^0_\\gamma)$ using photon-unparticle interactions for illustration.
2010-06-01
The organization of this thesis consists of three main ideas: the first presents the theoretical framework and experimental, as well as objects used in the analysis and the second relates to the various work tasks of service that I performed on the calorimeter, and the third is the search for the Higgs boson in the channel ZH {yields} e{sup +}e{sup -}b{bar b}. Thus, this thesis has the following structure: Chapter 1 is an introduction to the standard model of particle physics and the Higgs mechanism; Chapter 2 is an overview of the complex and the acceleration of the Tevatron at Fermilab D0 detector; Chapter 3 is an introduction to physical objects used in this thesis; Chapter 4 presents the study made on correcting the energy measured in the calorimeter; Chapter 5 describes the study of certification of electrons in the calorimeter; Chapter 6 describes the study of certification of electrons in the intercryostat region of calorimeter; Chapter 7 Detailed analysis on the search for Higgs production in the channel ZH {yields} e{sup +}e{sup -}b{bar b}; and Chapter 8 presents the final results of the calculations of upper limits to the production cross section of the Higgs boson on a range of low masses.
Pulsed D-D Neutron Generator Measurements of HEU Oxide Fuel Pins
2009-04-01
Pulsed neutron interrogation measurements have been performed on highly enriched uranium (HEU) oxide fuel pins and depleted uranium (DU) metal using a D-D neutron generator (2 x 10{sup 6} neutrons-s{sup -1}) and moderated {sup 3}He tubes at the Idaho National Laboratory Power Burst Facility. These measurements demonstrate the ability to distinguish HEU from DU by coincidence counting using a pulsed source. The amount of HEU measured was 8 kg in a sealed 55-gallon drum compared to 31 kg of DU. Neutron events were counted during and after the pulse with the Nuclear Materials Identification System (NMIS) and used to calculate the neutron coincidence time distributions. Passive measurements were also performed for comparison with the pulsed measurements. This paper presents the neutron coincidence distribution and Feynman variance results from the measurements.
Calculating Capstone Depleted Uranium Aerosol Concentrations from Beta Activity Measurements
2009-03-01
Beta activity measurements were used as surrogate measurements of uranium mass in aerosol samples collected during the field testing phase of the Capstone Depleted Uranium (DU) Aerosol Study. These aerosol samples generated by the perforation of armored combat vehicles were used to characterize the depleted uranium (DU) source term for the subsequent human health risk assessment (HHRA) of Capstone aerosols. Establishing a calibration curve between beta activity measurements and uranium mass measurements is straightforward if the uranium isotopes are in equilibrium with their immediate short-lived, beta-emitting progeny. For DU samples collected during the Capstone study, it was determined that the equilibrium between the uranium isotopes and their immediate short lived, beta-emitting progeny had been disrupted when penetrators had perforated target vehicles. Adjustments were made to account for the disrupted equilibrium and for wall losses in the aerosol samplers. Correction factors for the disrupted equilibrium ranged from 0.16 to 1, and the wall loss correction factors ranged from 1 to 1.92.
2009-01-01
Resume Cette Note presente la derivation du developpement asymptotique au 2nd ordre des valeurs et des fonctions propres de loperateur associe a une equation elliptique completee par une condition aux limites de Dirichlet sur un domaine forme de deux cavites reliees par un trou de petite taille. Le developpement asymptotique est effectue relativement a la taille du trou. La principale caracteristique de la methode est de donner lieu a une procedure numerique permettant de calculer les valeurs propres sans recourir a un maillage raffine autour du trou. Pour citer cet article : A. Bendali et al., C. R. Acad. Sci. Paris, Ser. I 347 (2009).
2003-07-01
The characterisation of the radioactive sources relative to the evolution of nuclear fuels or to the activation under particles flux (generally neutrons) of structures of a nuclear equipment or a simple isotope decay is a step in the radiation protection studies. This characterisation needs to know a fundamental knowledge: the radionuclides concentration. This one changes with time, and follows the coupled differential equations of first order in time, the generalised Bateman equations. The objective of this paper is to present the functionalities of the Darwin form, developed by the Cea and dedicated to the study of radioactivity. (N.C.)
Relativistic effects in the pionium lifetime; Effects relativistes dans la duree de vie du pionium
1999-10-01
The pionium decay width is evaluated in the framework of chiral perturbation theory and the relativistic bound state formalism of constraint theory. Corrections of order O({alpha}) are calculated with respect to the conventional lowest-order formula, in which the strong interaction amplitude has been calculated to two-loop order with charged pion masses. The global correction is found to be of the order 7%, the main part of which (6.4%) comes from the electromagnetic mass shift effects of the pions. (authors)
2007-07-01
The CPR ISMIR is a CEA-CNRS program on the behaviour of materials submitted to irradiation; it has been begun to support the applied current research programs on the aging of nuclear fuels, the storage and incineration matrices and the future reactors. Its aim is to contribute to scientifically set up the methods for anticipating the behaviour of ceramic materials under irradiation in using the important development of calculation means. Thus have been developed the basic knowledge and the interactions physics and calculation models at pertinent scales have been elaborated. (O.M.)
2007-01-01
The CPR ISMIR is a CEA-CNRS program on the behaviour of materials submitted to irradiation. It has been begun to support the applied current research programs on the aging of nuclear fuels, the storage and incineration matrices and the future reactors. Its aim is to contribute to scientifically set up the methods for anticipating the behaviour of ceramic materials under irradiation in using the important development of calculation means. Thus have been developed the basic knowledge and the interactions physics and calculation models at pertinent scales have been elaborated. (O.M.)
1997-12-31
This paper presents the modeling of a transferred electric arc inside a bath of melted metal. After a recall of the context of the study, the problem of the modeling, which involves magnetohydrodynamic coupling inside the arc and the bath, is described. The equations that govern the phenomena inside the arc and the bath are recalled and the approach used for the modeling of the anode region of the arc is explained using a 1-D sub-model. The conditions of connection between arc and bath calculations are explained and calculation results obtained with a 200 kW laboratory furnace geometry are presented. (J.S.) 8 refs.
The dynamic behavior of a reactor can be numerically determined in an acceptable period of time by a calculator of average speed. The method of the Duhamel integrals used has the advantage that the external reactivity can be varied discontinuously without affecting the precision adversely. The study of thermal effects is incorporated in the proposed program and does not entail any additional complications. (T.R.H.)
1967-07-01
Starting from kinetic equations derived from the Fokker Planck term introduced by Chandrasekhar, the dispersion relation of a homogeneous plasma is obtained easily through the use of a convenient set of eigenvalue functions. (author) [French] On etablit la relation de dispersion d'un plasma homogene, dont les collisions entre particules sont decrites au moyen du terme de Fokker Planck introduit par Chandrasekhar, en utilisant un systeme de fonctions propres, convenablement adapte. (auteur)
Stau-catalyzed big-bang nucleosynthesis reactions
2010-01-01
We study the new type of big-bang nucleosynthesis (BBN) reactions that are catalyzed by a hypothetical long-lived negatively charged, massive leptonic particle (called X-) such as the supersymmetric (SUSY) particle stau, the scalar partner of the tau lepton. It is known that if the X- particle has a lifetime of tauX
1965-07-01
The studies of interaction of slow neutrons with atomic nuclei by means of the time of flight methods are made with a pulsed neutron source with a broad energy spectrum. The measurement accuracy needs a high intensity and an output time as short as possible and well defined. If the neutrons source is a target bombarded by the beam of a pulsed accelerator, it is usually required to slow down the neutrons to obtain a sufficient intensity at low energies. The purpose of the Monte-Carlo method which is described in this paper is to study the slowing down properties, mainly the intensity and the output time distribution of the slowed-down neutrons. The choice of the method and parameters studied is explained as well as the principles, some calculations and the program organization. A few results given as examples were obtained in the line of this program, the limits of which are principally due to simplifying physical hypotheses. (author) [French] l'etude de l'interaction des neutrons lents avec les noyaux atomiques par la methode du temps de vol s'effectue avec une source pulsee de neutrons dont le spectre en energie est assez etendu. La precision des mesures demande que la source soit intense et que la duree d'emission des neutrons soit breve et bien definie. Si la source est une cible bombardee par le faisceau de particules d'un accelerateur pulse, il est generalement indispensable de ralentir les neutrons pour avoir une intensite suffisante a basse energie. Nous presentons ici une methode de Monte-Carlo pour l'etude detaillee de ce ralentissement, notamment l'intensite et la distribution des temps de sortie des neutrons ralentis. Cette presentation comprend: la justification du choix de la methode de Monte-Carlo, les principes generaux, les differentes etapes du calcul et du programme ecrit pour le calculateur electronique IBM 7090. Nous indiquons aussi les restrictions qui sont apportees au domaine d'application de ce programme et qui proviennent surtout des aproximations dans la description du systeme physique etudie. Quelques exemples sont donnes pour illustrer cette methode. (auteur)
1961-06-15
Colloidal gold-198 makes it possible to obtain clear images of hepatic parenchyma; the examination can be repeated from different angles thus demonstrating the presence of pathologically inert regions, whether they be hydatic cysts, abscesses or neoplasia. The study of the disappearance curve for the colloid, together with a measurement of the blood volume, makes it possible also to calculate the hepatic flow. Using Rose Bengal marked with iodine-131, it is possible to obtain images of the liver and of the bile ducts, and to follow the elimination of the dye in the intestines. The simultaneous recording of the disappearance curves for the blood and of the appearance of the dye in the intestines constitutes an useful working test which is particularly sensible for evaluating the permeability of the bile ducts and, to a certain degree, the site of an obstruction. (author) [French] L'or colloidal-198 permet d'obtenir avec nettete des images du parenchyme hepatique; l'examen peut etre repete sous plusieurs incidences mettant ainsi en evidence les zones muettes pathologiques, qu'il s'agisse de kystes hydatiques, d'abces ou de neoplasies. L'etude de la courbe d'epuration du colloide completee par une mesure du volume sanguin offre en outre la possibilite de calculer le debit hepatique. A l'aide du rose bengale marque a l'iode-131, il est possible d'obtenir des images du foie et de la vesicule biliaire, et de suivre l'elimination intestinale du colorant. L'enregistrement simultane des courbes d'epuration sanguine et d'apparition intestinale constitue une epreuve fonctionnelle particulierement sensible pour apprecier la permeabilite des voies biliaires et dans une certaine mesure le site d'une obstruction. (auteur)
1999-10-01
A pile foundation of the polyvalent building in the north quarter of the Federal Institute of Technology in Lausanne (EPFL) was equipped with a hydraulic circuit in order to be able to inject heat into the pile (i.e. the pile was transformed into a heat exchanger pile). Load, deformation and temperature sensors were installed in the pile in order to assess the influence of thermal solicitations on the static behaviour of the pile. In the initial phase of the project (up to May 1998), the design and realisation of the heat exchanger pile was scheduled together with the installation of the measurement sensors. The next phase, ending one month after publication of the present report, is comprised of series of thermal solicitations applied in the pile, called tests. Due to the construction of the building, the weight on the pile increases between each test. This report contains the presentation of all the measurements done in the 6 tests performed in between the completion of each floor of the building. The pile was heated with a temperature difference of 15 K for each test, except for the first one, where it reached 22 K (this was before the construction of the building`s basement). The temperatures and deformations induced by the thermal and mechanical solicitations were measured and the stresses calculated at different depths of the pile (fluid temperatures, flow rate, electric and thermal powers) were continuously recorded. Sonic coring and a control using the reflection method were performed to determine the pile elastic modulus and the quality of its concrete. The last phase of the project (March - December 1999) deals with the analysis of the measurements in order to assess the influence of a temperature variation on the ability of the pile to support the load of the building [Francais] Un pieu du batiment polyvalent du Quartier Nord de l`Ecole Polytechnique Federale de Lausanne (EPFL) a ete equipe d`un circuit hydraulique pour pouvoir lui injecter de la chaleur, 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
1963-07-01
A dynamic method has been developed for measuring Young's modulus and the rigidity modulus using the 'Forster Elastomat'. The principle consists in the determination of the resonance frequencies of graphite samples submitted to transverse, longitudinal, and torsional vibrations. The first two modes of vibration make it possible to calculate the elasticity modulus or the Young's modulus E, the third mode makes possible the calculation of the rigidity modulus G. The relationships from which the moduli E and G are measured are given. A systematic study has been made of graphite samples produced by extrusion or compression and submitted afterwards to one or several impregnations with pitch. For graphites made from the same coke by the same method, a linear relationship has been found for Young's modulus as a function of the apparent density. For the same apparent density, graphites made from different starting materials have generally different Young's moduli that bear a relationship to the crystalline characteristics of the material. The measurements of the rigidity modulus C made on different graphites also show the influence of crystallite orientation. (authors) [French] Une methode de mesure dynamique du module d'Young et du module de rigidite du graphite utilisant 'l'Elastomat Forster' a ete mise au point. Le principe consiste a determiner les frequences de resonance d'echantillons de graphite soumis a des vibrations transversales, longitudinales et de torsion. Les deux premiers modes de vibration permettent de calculer le module d'elasticite ou module d'Young E, le troisieme mode de vibration permet de calculer le module de rigidite G. Apres avoir decrit la methode de mesure, on rappelle les relations qui permettent de calculer les modules E et G. L'etude systematique d'echantillons de graphite, fabriques par filage ou pressage et ayant subi eventuellement une ou plusieurs impregnations au brai a ete effectuee. Pour les graphites issus du meme coke et fabriques selon un mode determine, une relation lineaire, module d'Young - densite apparente a ete mise en evidence. A densite apparente egale, des graphites realises avec des produits de base differents possedent generalement des modules d'Young differents en relation avec les caracteristiques cristallines du materiau. Les mesures du module de rigidite C faites sur differents graphites, montrent egalement l'influence de l'orientation des cristallites. (auteurs)
DuPont announces 2005 Lavoisier Medal honorees
2005-04-08
DuPont today announced the recipients of the Lavoisier Medal for Technical Achievement – presented each year to DuPont scientists and engineers who have made outstanding contributions to DuPont and their scientific ...
2007-01-01
This work deals with the ultrasonic nondestructive testing of parts with complex geometries using soft multi-element sensors. The different types of contact control configurations are presented first. Then, the difficulties encountered with conventional contact transducers are explained and the multi-element piezoelectric transducers technology, developed to meet these difficulties, is presented. The second chapter presents the results of finite-element calculations showing the complexity of a transducer in a condition of testing utilization. In a same configuration, the radiated far field calculated by finite-elements is compared to the measurement in order to validate the way the source behaviour is calculated. However, despite the efficiency of the finite-elements simulation, this tool is numerically too costly and cannot be used to optimize a full ...
1962-07-01
The study of the hyperfine structure and isotope shift enabled the positions of the first five levels of the multiplet {sup 7}F{sub 0-6} belonging to the fundamental configuration 5f{sup 6}7s{sup 2} to be determined. The classification of the arc spectrum begun in this way led to 25 odd levels, the number of classified lines (70) representing about 30 p. 100 of the light emitted by this hollow cathode in the visible. In addition, the isotope shifts of many lines and the data given by the King furnace show that the first levels of the configuration 5f{sup 5}6d7s{sup 2} are also low less than 8000 cm{sup -1} above the fundamental level {sup 7}F{sub 0}. The proximity of the configuration f{sup 6}s{sup 2} and f{sup 5}ds{sup 2} shows that the bonding energies of the 5f and 6d electrons are of the same order of magnitude and this fact must be responsible for the multiple valences belonging to plutonium. From the hyperfine structure of spark lines (Pu II) the interval factor a{sub 7} for the electron was deduced giving for the calculated nuclear moment of {sup 239}Pu a value of +0.21 {+-}0.06 {mu}{sub N}. The position of the hyperfine components show that the nuclear moment is positive, although the theoretical value given by B. R. Mottelson and S. Nillson is negative and equal to -0.1 {mu}{sub N}. (author) [French] Partie 1 - L'etude des structures hyperfines et du deplacement isotopique des raies du spectre d'arc du plutonium a permis de determiner la position des cinq premiers niveaux du multiplet {sup 7}F{sub 0-6} correspondant a la configuration fondamentale 5f{sup 6}7s{sup 2}. Des lors, la classification du spectre d'arc du plutonium pouvait etre amorcee: 25 niveaux impairs ont ete mis en evidence et le nombre de raies classees (70) represente environ 30 p. 100 de l'intensite totale du spectre d'arc emis par une cathode creuse dans le visible. D'autre part, le deplacement isotopique de certaines raies, joint aux renseignements donnes par le spectre emis par le four King, indique que les premiers niveaux de la configuration 5f{sup 5}6d7s{sup 2} se trouvent relativement bas - a moins de 8000 cm{sup -1} - du terme fondamental {sup 7}F{sub 0}. La proximite des configurations f{sup 6}s{sup 2} et f{sup 5}ds{sup 2} montre que les energies de liaison des electrons 5f et 6rf different peu et ce fait est a rapprocher des multiples valences observees dans le cas du plutonium. Partie II. - A partir des structures hyperfines des raies de Pu II nous avons evalue le facteur d'intervalle a7g de l'electron 7s et la valeur du moment magnetique ainsi deduite est egale a + 0,21 {+-} 0,06 {mu}{sub N}. La disposition des composantes hyperfines permet d'affirmer que le moment magnetique est positif alors que la valeur theorique donnee par B. R. Mottelson et S. Nillson est negative et egale a - 0,1 {mu}{sub N}. (auteur)
1958-07-01
The reaction probabilities in an infinite and homogeneous medium of BeO or Be have been calculated from neutron cross-section curves, for a neutron produced with an energy distribution similar to a fission spectrum; the calculation shows that, after several elastic collisions, the neutron has yet an appreciable probability to undergo a reaction, in spite of the energy degradation in the spectrum due to each collision. This degradation has been calculated, taking into account of anisotropy of the collisions. The gain of the reactivity in a reactor has been obtained after correcting these probabilities for the attenuation of the flux of fission neutrons due to the inelastic scattering in the uranium. Finally, the calculation shows that in a power reactor, this gain of reactivity is in practice destroyed in a few years by the accumulation of poisonous nuclei such as Li{sup 6} and He{sup 3} following (n, {alpha}) reaction. (author) [French] Les probabilites de reaction en milieu infini et homogene de glucine (BeO) ou de beryllium ont ete calculees a partir des courbes de section efficace pour un neutron naissant suivant un spectre de fission; le calcul montre qu'apres plusieurs diffusions elastiques le neutron a encore une probabilite appreciable de subir une reaction, malgre la degradation du spectre a chaque diffusion; cette degradation a ete calculee en tenant compte de l'anisotropie du choc. Le gain de reactivite dans un reacteur a ensuite ete obtenu en corrigeant les probabilites en milieu homogene de l'effet l'attenuation du flux des neutrons de fission par les chocs inelastiques dans les barres d'uranium. Enfin, le calcul montre que, dans un reacteur de puissance, ce gain de reactivite est pratiquement detruit en peu d'annees par l'accumulation de noyaux poisons Li{sup 6} et He{sup 3} consecutive a la reaction (n, {alpha}). (auteur)
1969-07-01
The results of experiments in the light water cooled D{sub 2}O reflected critical assembly ALIZE III have been compared to calculations. A diffusion model was used with 3 fast and epithermal groups and two overlapping thermal groups, which leads to good agreement of calculated and measured power maps, even in the case of strong variations of the neutron spectrum in the core. The difference of calculated and measured k{sub eff} was smaller than 0.5 per cent {delta}k/k. Calculations of void and structure material coefficients of the reactivity of 'black' rods in the reflector, of spectrum variations (Cd-ratio, Pu-U-ratio) and to the delayed photoneutron fraction in the D{sub 2}O reflector were made. Measurements of the influence of beam tubes on reactivity and flux distribution in the reflector were interpreted with regard to an optimum beam tube arrangement for the Franco- German High Flux Reactor. (author) [French] Les resultats des experiences faites dans la maquette critique ALIZE III, refrigeree a l'eau legere et reflechie par l'eau lourde, ont ete compares aux calculs. On a utilise un modele de la theorie de diffusion a trois groupes rapides et epithermiques et deux groupes thermiques qui se recouvrent. Ce modele a permis de calculer la distribution de puissance dans le coeur en bon accord avec les mesures, meme dans le cas d'une forte variation du spectre des neutrons dans le coeur. L'erreur entre k{sub eff} calcule et mesure etait inferieure a 0,5 pour cent {delta}k/k. Le coefficient de vide et des materiaux de structure, la reactivite des barres 'noires', les variations du spectre (rapport Cd, rapport Pu/U) et la fraction des photo-neutrons retardes sont egalement calcules. Les mesures de reactivite et de perturbation de flux dans le reflecteur, dues aux canaux, ont ete interpretees du point de vue d'un arrangement optimum des canaux pour le Reacteur a Haut Flux Franco-Allemand. (auteur)
1969-07-01
A method has been developed for determining the iron, nickel and chromium content of sintered ternary oxide rods designed to simulate structural elements in the reactor Masurca. During this work a calculation was made of the conditional constant of the Fe-EDTA complex in a formic buffer solution, and of that, of the Ni-EDTA complex in an ammoniacal buffer. From these two values it appears that it is not possible to carry out the iron and nickel determinations with a standard EDTA solution when these two elements are present simultaneously. That is the reason for which, in this case, a separation of the Fe and Ni is carried out in 8 N HCl solution on an anion exchange resin. Each element is then dosed by titricolorimetry. Chromium is determined by the same technique without prior separation. The reproducibility of the method has been calculated for each of the three elements. The relative accuracy is: 0.58 per cent for the iron; 1.41 per cent for the nickel; 0.39 per cent for the chromium. (authors) [French] Un mode operatoire a ete mis au point pour determiner la teneur en fer, nickel et chrome des reglettes d'oxydes frittes ternaires destinees a la simulation des elements de structure dans le reacteur MASURCA. Au cours de ce travail, nous avons calcule la constante conditionnelle du complexe Fe-EDTA en tampon formique et celle du complexe Ni-EDTA en tampon ammoniacal. De ces deux valeurs il apparait qu'il n'est pas possible d'effectuer le dosage du fer et du nickel par une solution titree d'EDTA quand ces deux elements sont en presence l'un de l'autre. C'est pourquoi, dans ce cas, on procede a une separation Fe-Ni en milieu HCl 8 N a l'aide d'une resine echangeuse d'anions. On dose ensuite chacun de ces elements par titricolorimetrie. Le chrome est determine par la meme technique sans separation prealable. La reproductibilite de la methode a ete calculee pour chacun des trois elements. La precision relative est de: 0.58 pour cent pour le fer; 1.41 pour cent pour le nickel; 0.39 pour cent pour le chrome. (auteurs)
1963-07-01
This note constitutes the first edition of a Handbook for the calculation of reactor protections. This handbook makes it possible to calculate simply the different neutron and gamma fluxes and consequently, to fix the minimum quantities of materials necessary under general safety conditions both for the personnel and for the installations. It contains a certain amount of nuclear data, calculation methods, and constants corresponding to the present state of our knowledge. (authors) [French] Cette note constitue la premiere edition du 'Formulaire sur le calcul de la protection des reacteurs'. Ce formulaire permet de calculer de facon simple les difterents flux de neutrons et de gamma et, par suite, de fixer les quantites minima de materiaux a utiliser pour que les conditions generales de securite soient respectees, tant pour le personnel que pour les installations. Il contient un certain nombre de donnees nucleaires, de methodes de calcul et de constantes correspondant a l'etat actuel de nos connaissances. (auteurs)
Mthode d'tude de la stabilit des ensembles convertisseurs-filtres
Each system which consists of a filter loaded by a converter absorbing a constant power is a system which is potentially unstable. In this document, models are developed for the study of the stability, in which current source is used to represent the converter. Using small signal hypothesis, the first model leads to analytical and numerical stability criteria, which are functions of the system parameters. In the second part, we use a large signal model, to obtain limit cycles of stability applying numerical calculation. This way we can study the influence of the system parameters on the area where the system is stable. Ljapunov theory is applied, to describe functions which represent part of the stable area we obtained by numerical calculation. Tout systme constitu d'un filtre charg par un convertisseur statique qui absorbe une puissance constante est un systme potentiellement instable. Nous dveloppons dans cet article deux modles pour l'tude de la stabilit, dont le point de dpart est la reprsentation du convertisseur par une source de courant. Par une hypothse petit signal, un premier modle permet l'obtention de critres de stabilit par tude analytique puis numrique. Dans un deuxime temps, nous considrons un modle fort signal, pour obtenir par calcul numrique le trac de cycles limites de stabilit. Cela permet l'tude de l'aire de fonctionnement stable du systme, en fonction des valeurs des paramtres du circuit. Enfin, l'aide des fonctions de Ljapunov, nous dfinissons analytiquement des contours dlimitant une partie des aires de fonctionnement stable dtermines par calcul numrique.
1963-07-01
in this paper, the problem of the evolution of the amounts of nuclides during radioactive transformations is resolved according to the classical laws of the radioactivity by using systematics in which the nuclides and their nuclear parameters are indexed. This method involves a simple classification of the nuclear parameters according to their nature. It leads to a matrix equation, the resolution of which was entrusted to the care of the ''Service de Calcul Electronique du Centre d'Etudes Nucleaires de Fontenay-aux-Roses'' which established a computer program. Calculations have been made with the IBM 1090-94 computer of Saclay. (authors) [French] Dans ce rapport, le probleme de l'evolution des quantites de nucleides lors de transformations radioactives est traite a l'aide des lois classiques de la radioactivite, en utilisant une systematique d'indiciation des nucleides et de leurs parametres nucleaires. Cette methode implique un classement simple des parametres nucleaires suivant leur nature. Elle conduit a une equation matricielle dont la resolution a ete confiee aux soins du ''Service de Calcul Electronique du Centre d'Etudes Nucleaires de Fontenay-aux-Roses'' qui a etabli un programme. Des calculs ont ete effectues sur le calculateur IBM 7090-94 de Saclay. (auteurs)
1969-04-01
By introducing an additional parameter F{sub 0}, the processes known hitherto for calculating heat transfer are extended to the heat flux distributions following an exponential law q{sub w} = exp(mx) which give a heat transfer coefficient, independent of position for laminar and turbulent flow with a linear pressure drop. For laminar flow along a semi-infinite plate, the heat flux distribution in accordance with the law qw = x{sup m} leads to the Nusselt number, regardless of the position. Nu is then determined by the thickness of the thermal boundary layer. For the annular space, the equations for explicit calculation of the temperature field will be given, as well as the Nusselt number in laminar flow and constant heat flux. In turbulent flow, the laws of distribution of eddy diffusivity for momentum in a tube, established by H. Reichardt, adapted for the annular space and the tube bundle, give the velocity field and the coefficient of friction and thus permit solution of the heat transfer equations. The results of the numerical calculation are given in the tables and diagrams for an extended range of the various parameters and compared with the experimental results. A simple process to determine the lower limit of the thermal entry length will be described. (author) [French] Par l'introduction d'un parametre supplementaire F{sub 0}, les procedes connus jusqu'a present pour le calcul du transfert de chaleur sont etendus aux repartitions exponentielles q{sub w} = exp(mx) du flux de chaleur qui indiquent un coefficient de transfert de chaleur independant de l'endroit pour l'ecoulement laminaire ou turbulent avec chute de pression lineaire. Pour l'ecoulement laminaire le long d'une plaque plane, la repartition du flux de chaleur selon la loi q{sub w} = x{sup m} conduit au nombre de Nusselt independant de l'endroit. Nu est alors determine par l'epaisseur de la couche limite thermique. Pour l'espace annulaire, seront indiquees les equations pour le calcul explicite du champ de temperature ainsi que le nombre de Nusselt en ecoulement laminaire et flux de chaleur constant. En ecoulement turbulent, les lois concernant la repartition de la diffusivite de quantite de mouvement dans un tube, etablies par H. Reichardt et adaptees a l'espace annulaire et au faisceau tubulaire, permettent la determination du champ de vitesse et du coefficient de perte de charge et consequemment la solution des equations de transfert de chaleur. Les resultats du calcul numerique sont rassembles dans des tableaux et representes par des diagrammes pour un domaine etendu des differents parametres et compares avec des resultats experimentaux. Par un procede simple, on peut determiner la valeur minimale de la longueur d'etablissement du regime thermique. (auteur)
1966-05-01
In studying the competitiveness of a nuclear merchant vessel, economic assessments in terms of figures were discarded in favor of a simplified model, which gives a clearer idea of the mechanism of the comparison between alternative vessels and the particular influence of each parameter. An expression is formulated for the unit cost per ton carried over a given distance as a function of the variables (speed and deadweight tonnage) and is used to determine the optima for conventional and nuclear vessels. To represent the freight market involved in the optimization studies, and thus in the competitiveness computation, two cases are taken into account: the tonnage to be carried annually is limited, and the tonnage to be carried annually is not limited. In both cases the optima are calculated and compared for a conventional and a nuclear vessel. Competitiveness curves are plotted as a function of the ratios of nuclear and conventional fuel costs and nuclear and conventional marginal power costs. These curves express the limiting values of the above two ratios for which the transport costs of the nuclear and conventional vessels are equal. The competitiveness curves vary considerably according to the hypothesis adopted for the freight market and the limit of tonnage carried annually. (author) [French] Pour etudier la competitivite du navire marchand nucleaire, plutot que de nous livrer a des evaluations economiques chiffrees, discutables dans l'etat actuel des etudes, nous utilisons un modele simplifie permettant de mieux saisir le mecanisme de la comparaison des navires et l'influence particuliere de chaque parametre. Nous etablissons une expression du cout unitaire de la tonne transportee sur un parcours donne en fonction des variables vitesse et port en lourd. Et nous l'utilisons pour determiner les optima des navires classiques et nucleaires. Pour representer le marche du fret qui intervient dans les etudes d'optimisation, et donc dans la recherche de la competitivite, nous considerons deux cas: 1) le tonnage a transporter annuellement est limite; 2) le tonnage a transporter annuellement n'est pas limite. Dans les deux cas, nous recherchons les optima du navire classique et du navire nucleaire, et nous les comparons. Nous construisons les courbes de competitivite en fonction des rapports des couts de combustible nucleaire et classique, et des couts marginaux de la puissance nucleaire et classique. Ces courbes traduisent les valeurs limites des deux rapports ci-dessus pour lesquelles les couts de transport du navire nucleaire et du navire classique sont egaux. Suivant les hypotheses adoptees pour le marche du fret et pour la limite du tonnage transporte annuellement, nous avons des courbes de competitivite tres differentes. De toute facon, c'est l'augmentation de puissance qui favorise le nucleaire. On peut obtenir cette augmentation en accroissant le deplacement ce qui est toujours interessant dans la mesure ou le fret le justifie, et en accroissant la vitesse, mais dans ce cas le modele met en evidence l'existence d'une limite. Le sous-marin peut presenter certains avantages (moindre resistance hydrodynamique de l'eau, possibilite de vitesse plus reguliere, et eventuellement reduction de trajet) qui rendent la competitivite du nucleaire plus aisee. (auteur)
1997-12-31
In order to determine the behaviour of the ventilation system in a MV/LV distribution substation, results of heating tests at different load levels have been used. Knowing the power generated by the transformer and the switchgear, and after calculating the power dissipated through the walls, it was possible to estimate the power evacuated by ventilation and thus the air flow through the grid. The resulting equations were introduced in the thermal model of the substation using the CLIM 2000 building heat engineering software. Simulation results are in agreement with experimental data
2001-07-01
Zirconium is employed as the 'inert' component in several different inert matrix fuel concepts being currently developed (CERMET, oxide solution, etc.). Relative to the situation in standard light water reactors, this implies a very significant increase in the zirconium inventory, with a correspondingly enhanced importance of the nuclear data for zirconium in calculating safety related parameters. The present paper discusses new results for various reactivity effects. On the basis of the current findings, it is recommended that a high priority be assigned to both the reduction of uncertainties in the epithermal data for zirconium and to the improvement of methods for resonance self-shielding of these data. (authors)
1996-12-31
Bibliographic studies in the domain of radiant heat transfers in complex geometries demonstrate the impossibility of resolving such problems using classical analytical methods. The numerical analysis can theoretically be performed successfully but requires enormous computer means. The contribution of this study consists in using computerized graphical techniques to treat general problems of radiant heat transfers in complex geometries. This paper presents the model used, the calculation technique and the optimizations that allow to greatly reduce the computer memory required and the calculation time. The code developed uses evocative images for the synthetic presentation of results which facilitate the searcher`s and conceiver`s choices. Finally, an application to the characterization of thermal comfort in residential environments is developed to illustrate the potentialities of this method. (J.S.) 19 refs.
Finite element simulations of coherent diffraction in elastoplastic polycrystalline aggregates
2010-01-01
RsumLa thorie continue de la plasticit cristalline est utilise pour prdire les figures de diffraction aux rayons X dans l'espace rciproque d'un polycristal mtallique. Lorsque l'chantillon se dforme de manire purement lastique, le champ de dplacement calcul par lments finis est utilis pour simuler les figures de diffraction. Ce n'est plus possible ds que la plasticit se dveloppe dans les grains tudis. C'est la distorsion lastique qui intervient alors pour le calcul de diffraction. Un champ de dplacement approch, bas sur un dveloppement de Taylor au premier ordre autour du centre d'un grain, est utilis pour la prvision des figures de diffraction dans le rgime plastique. On montre que l'usage de ce champ approch la place du dp...
1964-07-01
The study of the behaviour of the fuel during certain incidents or accidents in reactors is closely connected to the study of the changes in temperature. This document describes in the first part the main physical phenomena governing the kinetics of the accident. The aim is to know the temperatures at all points and at all times during the irregular regime which can follow the initial stable regime. In the second part an explanation is given of the numerical methods used. (authors) [French] L'etude du comportement du combustible lors de certains incidents ou accidents de pile est etroitement liee a l'etude de l'evolution des temperatures. Dans sa premiere partie, ce document decrit les phenomenes physiques principaux intervenant dans la cinetique de l'accident. Le but recherche est la connaissance des temperatures en tout point et a tout instant d'un regime varie, faisant suite a un regime initial stable. Dans la deuxieme partie les methodes numeriques employees sont explicitees. (auteurs)
A screening model for depleted uranium testing using environmental radiation monitoring data
Information from an ecological risk assessment of depleted uranium test areas at Yuma Proving Ground (YPG) was used to update the required environmental radiation monitoring (ERM) plan. Data to be collected for the ERM can also be used to evaluate the potential for adverse radiological and toxicological effects to terrestrial reptiles and mammals in the affected areas. We developed a spreadsheet-based screening model that incorporates the ERM data and associated uncertainties. The purpose of the model is to provide a conservative estimate of radiological exposure of terrestrial, biota to DU using the ERM data. The uncertainty in the estimate is also predicted so that the variation in the radiological exposure can be used in assessing potential adverse effects from DU testing. Toxicological effects are evaluated as well as radiological effects in the same program using the same data. Our presentation shows an example data set, model calculations, and the report of expected radiation dose rates and probable kidney burdens of select mammals and reptiles. The model can also be used in an inverse mode to calculate the soil concentration required to give either a radiological dose that would produce a potential adverse effect such as fatal cancer or a toxicological dose that would result in nephrotoxic effects in mammals.
A screening model for depleted uranium testing using environmental radiation monitoring data
1996-06-01
Information from an ecological risk assessment of depleted uranium test areas at Yuma Proving Ground (YPG) was used to update the required environmental radiation monitoring (ERM) plan. Data to be collected for the ERM can also be used to evaluate the potential for adverse radiological and toxicological effects to terrestrial reptiles and mammals in the affected areas. We developed a spreadsheet-based screening model that incorporates the ERM data and associated uncertainties. The purpose of the model is to provide a conservative estimate of radiological exposure of terrestrial, biota to DU using the ERM data. The uncertainty in the estimate is also predicted so that the variation in the radiological exposure can be used in assessing potential adverse effects from DU testing. Toxicological effects are evaluated as well as radiological effects in the same program using the same data. Our presentation shows an example data set, model calculations, and the report of expected radiation dose rates and probable kidney burdens of select mammals and reptiles. The model can also be used in an inverse mode to calculate the soil concentration required to give either a radiological dose that would produce a potential adverse effect such as fatal cancer or a toxicological dose that would result in nephrotoxic effects in mammals.
1965-07-01
MUDE is a nuclear code written in FORTRAN II for IBM 7090-7094. It resolves a system of difference equations approximating to the one-dimensional multigroup neutron scattering problem. More precisely, this code makes it possible to: 1. Calculate the critical condition of a reactor (k{sub eff}, critical radius, critical composition) and the corresponding fluxes; 2. Calculate the associated fluxes and various subsidiary results; 3. Carry out perturbation calculations; 4. Study the propagation of fluxes at a distance; 5. Estimate the relative contributions of the cross sections (macroscopic or microscopic); 6. Study the changes with time of the composition of the reactor. (authors) [French] MUDE est un code nucleaire ecrit en FORTRAN II pour IBM 7090-7094. Il resout un systeme d'equations aux differences approchant le probleme de diffusion neutronique multigroupe a une dimension. Plus precisement ce code permet de: 1. Calculer la condition critique d'un reacteur (k{sub eff}, rayon critique, composition critique) et les flux correspondants; 2. Calculer les flux adjoints et divers resultats connexes; 3. Effectuer des calculs de perturbation; 4. Etudier la propagation des flux a longue distance; 5. Ponderer des sections efficaces (macroscopiques ou microscopiques); 6. Etudier l'evolution de la composition du reacteur au cours du temps. (auteurs)
Lumbosacral epidural lipomatosis: MRI grading
2003-07-01
Lumbosacral epidural lipomatosis (LEL) is characterized by excessive deposition of epidural fat (EF). The purpose of our retrospective study was to quantify normal and pathologic amounts of EF in order to develop a reproducible MRI grading of LEL. In this study of 2528 patients (1095 men and 1433 women; age range 18-84 years, mean age 47.3 years) we performed a retrospective analysis of MRI exams. We obtained four linear measurements at the axial plane parallel and tangent to the superior end plate of S1 vertebral body: antero-posterior diameter of dural sac (A-Pd DuS), A-Pd of EF, located ventrally and dorsally to the DuS, and A-Pd of the spinal canal (Spi C). We calculated (a) DuS/EF index and (b) EF/Spi C index. We developed the following MRI grading of LEL: normal, grade 0: DuS/EF index {>=}1.5, EF/Spi C index {<=}40%; LEL grade I: DuS/EF index 1.49-1, EF/Spi C index 41-50% (mild EF overgrowth); LEL grade II: DuS/EF index 0.99-0.34, EF/Spi C index 51-74% (moderate EF overgrowth); LEL grade III: DuS/EF index {<=}0.33, EF/Spi C index {>=}75% (severe EF overgrowth). The MRI exams were evaluated independently by three readers. Intra- and interobserver reliabilities were obtained by calculating Kappa statistics. The MRI grading showed the following distribution: grade 0, 2003 patients (79.2%); LEL grade I, 308 patients (12.2%); LEL grade II, 165 patients (6.5%); and LEL grade III, 52 patients (2.1%). The kappa coefficients for intra- and interobserver agreement in a four-grade classification system were substantial to excellent: intraobserver, kappa range 0.79 [95% confidence interval (CI), 0.65-0.93] to 0.82 (95% CI, 0.70-0.95); interobserver, kappa range 0.76 (95% CI, 0.62-0.91) to 0.85 (95% CI, 0.73-0.97). In LEL grade I, there were no symptomatic cases due to fat hypertrophy. LEL grade II was symptomatic in only 24 cases (14.5%). In LEL grade III, all cases were symptomatic. A subgroup of 22 patients (42.3%) showed other substantial spinal pathologies (e.g., disk herniation). By means of simple reproducible measurements and indexes MRI grading enables a distinction between mild, moderate, and severe EF hypertrophy. Kappa statistics indicate that LEL can be reliably classified into a four-grade system by experienced observers. (orig.)
L'avis d'ouverture de chantier informatis$$bun moyen de prvention et de management
Linstruction de scurit IS 39 stipule que les travaux excuts par des entreprises sur le domaine du CERN doivent faire lobjet dun Avis dOuverture de Chantier (AOC) rdig par le superviseur des travaux avant le dmarrage de ceux-ci, dans le but dattirer lattention sur les risques et les nuisances quils peuvent engendrer pour les usagers dans la zone de travaux. A cet effet, un groupe de travail a spcifi une version informatise du document AOC sur EDH afin den faciliter la saisie, la visualisation ainsi que la gestion et larchivage ; cela sajoutent la description des risques et mesures prventives possibles, la consultation des diffrentes bases de donnes CFU (Contract Follow Up), du patrimoine immobilier et finalement toutes les commodits lies EDH pour le routage du document selon la liste des rles des personnes concernes (approbation, distribution pour information). Ds lors, lAOC devient un moyen danalyse et de gestion (dtection et traabilit des co-activits, des travaux selon les emplacements, firmes intervenantes et dates) grce aux diffrents critres et calculs selon lesquels il est manipul par les utilisateurs.
1959-07-01
The authors describe a procedure for the determination of the strontium radioisotopes 89 and 90. The concentration of strontium is made possible by the insolubility of its nitrate salt in strong nitric acid which allows the removal of greatest part of calcium. The purification is performed on a cation exchange column. The amount of radioisotope 90 is determined by means of its daughter product yttrium 90 necessary calibrations and computations are treated in special paragraphs. With regard to the reproducibility of the measurements, the fluctuations are less than 20 per cent. This seems satisfaction for such a technique which have great sensibility while being long and necessitative great carefulness. (author) [French] Les auteurs decrivent une technique de dosage des isotopes 89 et 90 du strontium. La concentration du strontium est assuree grace a l'insolubilite de son nitrate dans l'acide nitrique concentre, ce qui permet d'eliminer la plus grande partie du Ca. La purification se fait sur une colonne echangeuse de cations. L'isotope 90 est dose grace a son descendant l'yttrium 90. Les etalonnages et calculs necessaires font l'objet de paragraphes detailles. En ce qui concerne la reproductibilite des mesures, les fluctuations sont inferieures a 20 pour cent, ce qui semble satisfaisant devant la grande sensibilite de la methode qui reste cependant longue et delicate. (auteur)
1967-01-01
In the first part are studied the general relationships between the physical effects produced by neutrons in solids, and the total flux and neutron energy spectrum; some examples are given. The second part, describes the application to a silicon damage detector whose principle is to use the damage produced in a PIN Junction for measuring the neutron flux (intermediate and fast) received by the detector. Chapter I is devoted to the experimental determination of the energy given to the atoms by a primary in the silicon. The results and conclusions drawn from this determination make it possible to consider, in chapter II, the calculation of the detectors response characteristics.Chapter III deals with the measurement of the detectors response function and it is noted that good agreement is obtained between the calculation and experimental results. The whole of the second part constitutes a test of the methods presented in the first part. (author) [French] Dans la premiere partie, nous etudions les relations generales qui lient les effets physiques engendres par les neutrons dans les solides au flux integre et au spectre des neutrons et nous donnons des exemples d'utilisation. La deuxieme partie est une application au detecteur de dommages en silicium, dont le principe est d'utiliser les dommages crees dans une jonction PIN pour mesurer les flux de neutrons (intermediaires et rapides) recus par le detecteur. Le chapitre I est consacre a la determination experimentale de l'energie cedee aux atomes par un primaire dans le silicium. Les resultats et les conclusions que l'on peut tirer de cette determination permettent d'aborder, au chapitre II, le calcul de la fonction de reponse du detecteur. Le chapitre III porte sur la mesure de la fonction de reponse du detecteur et on constate qu'il y a un bon accord entre le calcul et l'experience. L'ensemble de la deuxieme partie constitue un test des methodes exposees dans la premiere partie. (auteur)
1998-06-01
To control fuel rods of PWR, a laboratory of the Cea, the LEMO (Laboratory of Study and Simulation) develops a finite element code TOUTATIS. Its allows the user to calculate the deformations connected to the pellet-clad systems and hence the Pellet-Cladding Interactions (PCI) induced by unilateral contact. This paper presents the code validation from a thermal point of view. The computerized simulation is compared to experimental results CALIF and EXTRAFORT, realized to the Cea in the experimental reactor OSIRIS. (A.L.B.)
2003-03-01
Presented are the standard devices for switch modular devices. Important for installation are most exact calculation of power losses and conditions for the surrounding environment where switch board operate. In detail steps for climatization passive ventilation and filter aerators; air/air heat exchangers; air/water heat exchangers; direct liquid cooling and central backcooling plants and last not least design tools as simulation and thermography. (GL)
The analog simulation of nuclear reactor problems except for the simulation of the kinetic equations is discussed. Various problems relative to temperature in a reactor, pipe, excharger, and turbine are studied, and simulation techaiques used by earlier workers are critically reviewed. It is shown the problem of pipe simulators can be solved by the use of specialized simulators which are described. The aspects of rotating machine simulators are discussed, and a simulator requiring both digital and analog methods is described. The thermodynamic problems of nuclear power stations are considered, and an example is given. (J.S.R.)
1966-01-01
The number of long half-life free radicals created by gamma irradiation in the bones of the rat has been determined from the electrons paramagnetic resonance spectrum. This number decreases slowly with time (calculated half life: 24 days). It is proportional to the dose of gamma radiation given to the rat. The method could find interesting applications in the field of biological dosimetry. (authors)
Estimates of the modeling error for the KirchhoffLove plate model
2010-01-01
RsumDans ce travail on considre le modle de KirchhoffLove pour approcher les problmes de plaques minces sous certaines conditions. Nous prsentons des majorants d'erreur calculables. La borne de l'erreur relative converge comme Formula Not Shown en terme du paramtre d'paisseur h pourvu que la KL solution ait un peu plus de rgularit.
1999-07-01
The energy deposited by electrons versus depth inside molded Epoxy packages is measured using optically stimulated luminescence (OSL) dose mapping technique. Longitudinal and transversal depth dose curves are investigated under various angles of irradiation. Experimental results are compared with PENELOPE transport code calculations. Preliminary results are in good agreement with simulations.
2003-07-01
A method is presented and illustrated to characterize a radioactive site from an integrated approach using a gamma scanner and a dose calculation tool in three dimensions based on the point - kernel method. (N.C.)
1983-01-01
The kinetic of 15N2 diffusion has been measured in a system similar to that for the estimation of N2 fixation in plant microorganism associations cultivated in soil. The 15N2 enrichment of the soil atmosphere reached an homogenous value one hour after injection of 15N2 and is identical to that obtained by calculation, indicating that no adsorption occurs in the soil particles. (orig.)
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