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Sample records for self-irradiation

  1. Self-irradiation study of plutonium alloys

    International Nuclear Information System (INIS)

    Oudot, B.

    2005-02-01

    The plutonium is unstable and produces α or β decays depending on the isotope. These decays generate americium, uranium, helium and different kinds of structural defects. The effects of self-irradiation damage are observed at macroscopic scale, the mechanism occurs from atomic scale. In order to improve our understanding of the self-irradiation effects in PuGa alloys, a technique sensitive to the vacancies and vacancies clusters has been developed: the Positron Annihilation Spectroscopy (PAS). The swelling has been characterized by XRD at a microscopic scale and by dilatometry at a macroscopic scale. Swelling starts just after melting and reaches a saturation between 6 and 36 months depending on the degree of gallium homogeneity in the alloy. Swelling at saturation increases with the gallium content, but the absolute change in the cell parameters is constant during time. PAS showed that vacancies clusters develop immediately. Their concentration increase with time. A part of these clusters is stabilized by helium atoms and leads to the creation of bubbles, which contribution to swelling is negligible. The vacancies and vacancies clusters which are not stabilized by helium contribute to the swelling increase by mechanisms known for other materials. These mechanisms are based on a 'dislocation bias'. The presence of these dislocations can furthermore explain the low mean life time value of positrons at the saturation point. (author)

  2. Helium bubbles aggravated defects production in self-irradiated copper

    Science.gov (United States)

    Wu, FengChao; Zhu, YinBo; Wu, Qiang; Li, XinZhu; Wang, Pei; Wu, HengAn

    2017-12-01

    Under the environment of high radiation, materials used in fission and fusion reactors will internally accumulate numerous lattice defects and bubbles. With extensive studies focused on bubble resolution under irradiation, the mutually effects between helium bubbles and displacement cascades in irradiated materials remain unaddressed. Therefore, the defects production and microstructure evolution under self-irradiation events in vicinity of helium bubbles are investigated by preforming large scale molecular dynamics simulations in single-crystal copper. When subjected to displacement cascades, distinguished bubble resolution categories dependent on bubble size are observed. With the existence of bubbles, radiation damage is aggravated with the increasing bubble size, represented as the promotion of point defects and dislocations. The atomic mechanisms of heterogeneous dislocation structures are attributed to different helium-vacancy cluster modes, transforming from the resolved gas trapped with vacancies to the biased absorption of vacancies by the over-pressured bubble. In both cases, helium impedes the recombination of point defects, leading to the accelerated formation of interstitial loops. The results and insight obtained here might contribute to understand the underlying mechanism of transmutant solute on the long-term evolution of irradiated materials.

  3. Alpha self irradiation effects in nuclear borosilicate glass

    International Nuclear Information System (INIS)

    Peuget, S.; Roudil, D.; Deschanels, X.; Jegou, C.; Broudic, V.; Bart, J.M.

    2004-01-01

    The properties of actinide glasses are studied in the context of high-level waste management programs. Reprocessing high burnup fuels in particular will increase the minor actinide content in the glass package, resulting in higher cumulative alpha decay doses in the glass, and raising the question of the glass matrix behavior and especially its containment properties. The effect of alpha self-irradiation on the glass behavior is evaluated by doping the glass with a short-lived actinide ( 244 Cm) to reach in several years the alpha dose received by the future glass packages over several thousand years. 'R7T7' borosilicate glasses were doped with 3 different curium contents (0.04, 0.4 and 1.2 wt% 244 CmO 2 ). The density and mechanical properties of the curium-doped glasses were characterized up to 2. 10 18 α/g, revealing only a slight evolution of the macroscopic behavior of R7T7 glass in this range. The leaching behavior of curium-doped glass was also studied by Soxhlet tests. The results do not show any significant evolution of the initial alteration rate with the alpha dose. (authors)

  4. Stochastic simulation of destruction processes in self-irradiated materials

    Directory of Open Access Journals (Sweden)

    T. Patsahan

    2017-09-01

    Full Text Available Self-irradiation damages resulting from fission processes are common phenomena observed in nuclear fuel containing (NFC materials. Numerous α-decays lead to local structure transformations in NFC materials. The damages appearing due to the impacts of heavy nuclear recoils in the subsurface layer can cause detachments of material particles. Such a behaviour is similar to sputtering processes observed during a bombardment of the material surface by a flux of energetic particles. However, in the NFC material, the impacts are initiated from the bulk. In this work we propose a two-dimensional mesoscopic model to perform a stochastic simulation of the destruction processes occurring in a subsurface region of NFC material. We describe the erosion of the material surface, the evolution of its roughness and predict the detachment of the material particles. Size distributions of the emitted particles are obtained in this study. The simulation results of the model are in a qualitative agreement with the size histogram of particles produced from the material containing lava-like fuel formed during the Chernobyl nuclear power plant disaster.

  5. Enhanced diffusion under alpha self-irradiation in spent nuclear fuel: Theoretical approaches

    International Nuclear Information System (INIS)

    Ferry, Cecile; Lovera, Patrick; Poinssot, Christophe; Garcia, Philippe

    2005-01-01

    Various theoretical approaches have been developed in order to estimate the enhanced diffusion coefficient of fission products under alpha self-irradiation in spent nuclear fuel. These simplified models calculate the effects of alpha particles and recoil atoms on mobility of uranium atoms in UO 2 . They lead to a diffusion coefficient which is proportional to the volume alpha activity with a proportionality factor of about 10 -44 (m 5 ). However, the same models applied for fission lead to a radiation-enhanced diffusion coefficient which is approximately two orders of magnitude lower than values reported in literature for U and Pu. Other models are based on an extrapolation of radiation-enhanced diffusion measured either in reactors or under heavy ion bombardment. These models lead to a proportionality factor between the alpha self-irradiation enhanced diffusion coefficient and the volume alpha activity of 2 x 10 -41 (m 5 )

  6. XRD monitoring of α self-irradiation in uranium-americium mixed oxides.

    Science.gov (United States)

    Horlait, Denis; Lebreton, Florent; Roussel, Pascal; Delahaye, Thibaud

    2013-12-16

    The structural evolution under (241)Am self-irradiation of U(1-x)Am(x)O(2±δ) transmutation fuels (with x ≤ 0.5) was studied by X-ray diffraction (XRD). Samples first underwent a preliminary heat treatment performed under a reducing atmosphere (Ar/H2(4%)) aiming to recover the previously accumulated structural defects. Over all measurements (carried out over up to a full year and for integrated doses up to 1.5 × 10(18) α-decay events·g(-1)), only fluorite U(1-x)Am(x)O(2±δ) solid solutions were observed. Within a few days after the end of the heat treatment, each of the five studied samples was slowly oxidized as a consequence of their move to air atmosphere, which is evidenced by XRD by an initial sharp decrease of the unit cell parameter. For the compounds with x ≤ 0.15, this oxidation occurred without any phase transitions, but for U0.6Am0.4O(2±δ) and U0.5Am0.5O(2±δ), this process is accompanied by a transition from a first fluorite solid solution to a second oxidized one, as the latter is thermodynamically stable in ambient conditions. In the meantime and after the oxidation process, (241)Am α self-irradiation caused a structural swelling up to ∼0.8 vol %, independently of the sample composition. The kinetic constants of swelling were also determined by regression of experimental data and are, as expected, dependent on x and thus on the dose rate. The normalization of these kinetic constants by sample α-activity, however, leads to very close swelling rates among the samples. Finally, evolutions of microstrain and crystallite size were also monitored, but for the considered dose rates and cumulated doses, α self-irradiation was found, within the limits of the diffractometer used, to have almost no impact on these characteristics. Microstrain was found to be influenced instead by the americium content in the materials (i.e., by the impurities associated with americium starting material and the increase of cationic charge heterogeneity with

  7. Long-term behaviour of bituminized waste: modelling self-irradiation and leaching

    International Nuclear Information System (INIS)

    Simondi-Teisseire, B.; Vistoli, P.P.; Libert, M.; Gilardi, T.; Chaix, P.; Blanc, V.

    2001-01-01

    During interim storage, the main evolution factor of bituminized wastes is radiolysis, due to self-irradiation. In deep disposal conditions, after site re-saturation and corrosion of the containers, the main evolution will be due to leaching. This paper deals with two models designed to describe respectively radiolytic gas evacuation (JACOB- 2) and bituminized waste leaching (COLONBO), and some of the typical results obtained from these two models. The first model describes radiolytic gas production, diffusive transport of gas, bubble nucleation and ripening and movement under buoyancy. The second one is based on descriptions of water sorption, solubilization, and diffusion into the matrix, water uptake by the most soluble salts leading to alteration of the matrix and finally to diffusive transport of the salts outside the bitumenisate. (author)

  8. Self irradiation effects on the thorium phosphate diphosphate dissolution (TPD): simulation by external irradiations

    International Nuclear Information System (INIS)

    Tamain, C.; Ozgumus, A.; Dacheux, N.; Garrido, F.; Thome, L.; Corbel, C.; Genet, M.

    2004-01-01

    The Thorium Phosphate Diphosphate (TPD), proposed as a ceramic for the long term immobilization of actinides, was externally irradiated with several ions and energies (but also with gamma rays) in order to simulate the self-irradiation. The influence of the electronic energy loss was first investigated. Thus, the XRD measurements have shown a complete amorphization of the material under 10 13 ions of Kr.cm -2 , while no significant structural change occurred after 5.10 13 S.cm -2 , 2.10 16 He.cm -2 or 320 kGy of dose of gamma rays. The dissolution of the raw and irradiated pellets was studied versus several parameters such as amorphized fraction, energy loss of incident ions, radiolytic species produced in situ in the leachate during irradiation (such as H 2 O 2 ), temperature and acidity. The results reveal an important increase of the dissolution kinetics for amorphized pellets compared to raw ceramic. (authors)

  9. Effect of alpha self irradiation on helium migration in (U,Pu)O2 samples

    International Nuclear Information System (INIS)

    Pipon, Yves; Roudil, Daniele; Jegou, Christophe; Khodja, Hicham; Raepsaet, Caroline

    2008-01-01

    The helium behavior and its migration mechanisms in nuclear spent fuel (UOX and MOX) significantly impact the possible evolution of the spent fuel matrix in a closed system during interim storage or during a disposal repository. An experimental study has been conducted on (U,Pu)O 2 samples in order to investigate the impact of defects created by alpha decay on helium diffusion. One large part is devoted to thermal atomic diffusion and applied on 3 He implanted samples, annealed at 850 and 1000 deg. C. The He profiles, as implanted and after annealing, were investigated with the 3 He(d,p) 4 He nuclear reaction. Another part deals with the thermal release of 4 He amassed in the samples. The measured thermal diffusion coefficients are compared with previously published values, thereby highlighting the effect of the alpha self-irradiation on helium behavior. (authors)

  10. Self-irradiation damage to the local structure of plutonium and plutonium intermetallics

    Energy Technology Data Exchange (ETDEWEB)

    Booth, C. H.; Jiang Yu; Medling, S. A. [Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Wang, D. L. [Nuclear Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Costello, A. L.; Schwartz, D. S.; Mitchell, J. N.; Tobash, P. H. [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Bauer, E. D. [Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); McCall, S. K.; Wall, M. A.; Allen, P. G. [Condensed Matter and Materials Division, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

    2013-03-07

    The effect of self-irradiation damage on the local structure of {delta}-Pu, PuAl{sub 2}, PuGa{sub 3}, and other Pu intermetallics has been determined for samples stored at room temperature using the extended x-ray absorption fine-structure (EXAFS) technique. These measurements indicate that the intermetallic samples damage at a similar rate as indicated in previous studies of PuCoGa{sub 5}. In contrast, {delta}-Pu data indicate a much slower damage accumulation rate. To explore the effect of storage temperature and possible room temperature annealing effects, we also collected EXAFS data on a {delta}-Pu sample that was held at less than 32 K for a two month period. This sample damaged much more quickly. In addition, the measurable damage was annealed out at above only 135 K. Data from samples of {delta}-Pu with different Ga concentrations and results on all samples collected from different absorption edges are also reported. These results are discussed in terms of the vibrational properties of the materials and the role of Ga in {delta}-Pu as a network former.

  11. Simulation of Self-Irradiation of High-Sodium Content Nuclear Waste Glasses

    International Nuclear Information System (INIS)

    Pankov, Alexey S.; Ojovan, Michael I.; Batyukhnova, Olga G.; Lee, William E.

    2007-01-01

    Alkali-borosilicate glasses are widely used in nuclear industry as a matrix for immobilisation of hazardous radioactive wastes. Durability or corrosion resistance of these glasses is one of key parameters in waste storage and disposal safety. It is influenced by many factors such as composition of glass and surrounding media, temperature, time and so on. As these glasses contain radioactive elements most of their properties including corrosion resistance are also impacted by self-irradiation. The effect of external gamma-irradiation on the short-term (up to 27 days) dissolution of waste borosilicate glasses at moderate temperatures (30 deg. to 60 deg. C) was studied. The glasses studied were Magnox Waste glass used for immobilisation of HLW in UK, and K-26 glass used in Russia for ILW immobilisation. Glass samples were irradiated under γ-source (Co-60) up to doses 1 and 11 MGy. Normalised rates of elemental release and activation energy of release were measured for Na, Li, Ca, Mg, B, Si and Mo before and after irradiation. Irradiation up to 1 MGy results in increase of leaching rate of almost all elements from both MW and K-26 with the exception of Na release from MW glass. Further irradiation up to a dose of 11 MGy leads to the decrease of elemental release rates to nearly initial value. Another effect of irradiation is increase of activation energies of elemental release. (authors)

  12. Electric resistivity of 241-americium and 244-curium metals. Creation of defects and isochronous annealing of 241-americium metal after self-irradiation

    International Nuclear Information System (INIS)

    Schenkel, R.

    1977-03-01

    The temperature dependence of the electrical resistivity of thin films of bulk 241 Am metal were measured between 300 and 4.5 K. The room temperature resistivity was found to be 68.90μΩcm. At room temperature the electrical resistivity of americium increases with pressure (3% up to 13 kbar). The application of 13 kbar pressure did not change the low temperature power law in the electrical resistivity. The resistivity vs temperature curve can be explained by assuming s-d scattering of conduction electrons. The localized 5f electrons are considered to be about 5eV below the Fermi level. Americium therefore should be the first lanthanide-like element in the actinide series. The defect production due to self-irradiation damage was studied by measuring the increase of the resistivity at 4.2 K over a period of 738 h. A saturation resistivity of 16.036 μΩcm was found corresponding to a defect concentration of about 0.22 a/o. After isochronal annealing two recovery stages were observed at about 65 and 145 K. The two stages shift with increasing initial defect concentration to lower temperatures. Estimates of the activation energies and the reaction order were made and possible defect reactions suggested. The magnetic contribution to the electrical resistivity of curium, which shows an antiferromagnetic transition at 52.5 k, was obtained by subtracting the resistivity of americium (to be considered as phonon part). Comparison with theoretical models were made. At low temperatures the measurements are strongly affected by self-irradiation damage [drho/dt(t=0)=9.8μΩcm/h

  13. EPR study of sodium plutonyl acetate NaPuO2(CH3COO)3 and plutonium thenoyl trifluoroacetonate Pu(TTA)4: self-irradiation effects

    International Nuclear Information System (INIS)

    Krishnamurty, M.V.

    1978-01-01

    High energy radiations are emitted in the radioactive disintegration of plutonium isotopes. These radiations mainly consisting of α-particles interact with the surrounding ligands in the case of plutonium compounds. The ligand molecules undergo electronic excitation, ionization and fragmentation resulting in extensive radiation damage. Electron paramagnetic resonance technique is utilised to indentify and estimate these molecular products formed as a result of self-irradiation in the case of sodium plutonyl acetate, NaPuO 2 (CH 3 COO) 3 , and plutonium thenoyl trifluoroacetonate, Pu(TTA) 4 . The observed EPR spectra are interpreted to be due to acetate and thenoyl trifluoroacetonate radicals with the unpaired electron localized on oxygens of carboxyl group and carbonyl group, respectively. The efficiency parameter, eta, defined as the ratio of the number of paramagnetic species/defects to the total number of radioactive disintegrations has been determined to be 0.83 and 16.9 for the case of the acetate and thenoyl trifluoroacetonate, respectivly. (author)

  14. On possibility of degradation of lava-like fuel-containing materials of the 4-th block of Chernobyl NPP under internal self-irradiation by alpha-particle sources

    International Nuclear Information System (INIS)

    Pazukhin, Eh. M.; Borovoj, A.A.; Rudya, K.G.

    2002-01-01

    It is shown that internal self-irradiation by alpha-particle beam cannot be a cause of change of strength characteristics of silicate matrix and so a cause of degradation of Chernobyl lava-like materials. A new method is proposed for management with lava-like fuel-containing materials of the 4-th block: vitrification in smelter unit situated in bubbler-basin and storage of prepared immobilized compacts in corresponding depositories [ru

  15. Alpha self-irradiation effects in ternary oxides of actinides elements: The zircon-like phases AmIIIVO4 and AIINpIV(VO4)2 (A=Sr, Pb)

    International Nuclear Information System (INIS)

    Goubard, F.; Griesmar, P.; Tabuteau, A.

    2005-01-01

    We report the experimental studies of irradiation damage from alpha decay in neptunium and americium vanadates versus cumulative dose. The isotopes used were the transuranium α-emitter 237 Np and the α,γ-emitter 241 Am. Neptunium and americium vanadates self-irradiation was studied by X-ray diffraction method (XRD). The comparison of the powder diffraction patterns reveal that the irradiation has no apparent effect on the neptunium phases while the americium vanadate swells and becomes metamict as a function of cumulative dose

  16. Self-irradiation effect on thermal conductivity of Zr{sub 0.70}Pu{sub 0.25}Cm{sub 0.05}N solid solution

    Energy Technology Data Exchange (ETDEWEB)

    Nishi, Tsuyoshi, E-mail: tsuyoshi.nishi.75@vc.ibaraki.ac.jp [Department of Materials Science and Engineering, College of Engineering, Ibaraki University, Hitachi, Ibaraki, 316-8511 (Japan); Hayashi, Hirokazu; Sato, Takumi; Takano, Masahide [Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Tokai-mura, Ibaraki, 319-1195 (Japan)

    2017-04-01

    This study evaluated the dependence of the thermal conductivity of Zr{sub 0.70}Pu{sub 0.25}Cm{sub 0.05}N on storage time and temperature. The authors prepared sintered samples of Zr{sub 0.70}Pu{sub 0.25}Cm{sub 0.05}N solid solution and measured thermal diffusivity at storage times of 0, 24, 72, 144, 240, 408, 552, 816, 1,680, and 2064 h, from which it was determined that the thermal conductivity decreased exponentially with increasing storage time. This result suggests that the decrease of the thermal conductivity could be attributed to the accumulation of lattice defects from self-irradiation. To confirm the thermal recovery behavior of Zr{sub 0.70}Pu{sub 0.25}Cm{sub 0.05}N under annealing, thermal diffusivity was also measured just after annealing. The thermal conductivity of Zr{sub 0.70}Pu{sub 0.25}Cm{sub 0.05}N was determined to be larger than that of Zr{sub 0.58}Pu{sub 0.21}Cm{sub 0.21}N but smaller than that of Zr{sub 0.80}Pu{sub 0.10}Cm{sub 0.10}N. - Highlights: •The authors prepared Zr{sub 0.70}Pu{sub 0.25}Cm{sub 0.05}N and measured thermal diffusivity. •Dependence of thermal conductivity on storage time was clarified. •After annealing at 1423 K in vacuum, thermal conductivity was recovered.

  17. Carbon nanotubes polymerization induced by self-irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Moura, Cassio Stein [Faculdade de Fisica, Pontificia Univ. Catolica do Rio Grande do Sul (PUCRS), Porto Alegre (Brazil)

    2008-07-01

    Full text: We discuss our recent results on the formation of cross-links between neighboring carbon nanotubes within a bundle. Classical molecular dynamics was used to follow the evolution of the system when it is bombarded by low-energy carbon atoms. We show that it is possible to polymerize carbon nanotubes through irradiation and discuss the most common types of defects produced. Cross-links are created mainly in the direction perpendicular to the surface, and for higher energies, defects are created deeper in the rope. The final defects geometries may provide a realistic input to electronic density first principle calculations. (author)

  18. Carbon nanotubes polymerization induced by self-irradiation

    International Nuclear Information System (INIS)

    Moura, Cassio Stein

    2008-01-01

    Full text: We discuss our recent results on the formation of cross-links between neighboring carbon nanotubes within a bundle. Classical molecular dynamics was used to follow the evolution of the system when it is bombarded by low-energy carbon atoms. We show that it is possible to polymerize carbon nanotubes through irradiation and discuss the most common types of defects produced. Cross-links are created mainly in the direction perpendicular to the surface, and for higher energies, defects are created deeper in the rope. The final defects geometries may provide a realistic input to electronic density first principle calculations. (author)

  19. Thermal stability of products from self-irradiated Ca sup 14 CO sub 3

    Energy Technology Data Exchange (ETDEWEB)

    Albarran, G. (Universidad Nacional Autonoma de Mexico, Mexico City (Mexico). Inst. de Ciencias Nucleares); Collins, K.E.; Collins, C.H. (Universidade Estadual de Campinas, SP (Brazil). Inst. de Quimica)

    1991-01-01

    Five {sup 14}-labelled organic acids are obtained from the self-radiolysis of high specific activity Ca{sup 14}CO{sub 3}. The yields of all products decrease upon isothermal annealing at 548 K. Upon isochronal annealing (1 h), no significant changes occur up to 423 K. In the temperature interval between 476 and 673 K, the yields of formic, oxalic and glyoxylic acids decrease similarly, suggesting that they have the same precursor: the CO{sub 2}{sup -} radical. The isochronal annealing behaviours of the precursors of glycolic and acetic acids are more complex and involve other solid state species. (author).

  20. Effects of Self Irradiation from 238Pu on Candidate Ceramics for Plutonium Immobilization

    International Nuclear Information System (INIS)

    Strachan, Denis M.; Scheele, Randall D.; Kozelisky, Anne E.; Sell, Rachel L.

    2003-01-01

    In this document, we describe the results of radiation damage testing and characterization for specimens that were resintered to re-establish crystallinity. The phases in these specimens have become amorphous from radiation induced damage over the 8 months since sintering

  1. Self-irradiation damage in 4H-SiC by molecular dynamics simulation

    International Nuclear Information System (INIS)

    Han Miaomiao; Wang Qingyu; Li Taosheng; Li Zhongyu

    2014-01-01

    The development of nuclear technology is closely and inseparably related to the improvements of materials irradiation performance. The irradiation damage of nuclear materials is an important issue of characteristics and difficulties. Because of the excellent features, SiC becomes one of the candidate materials for the cladding material and structure material in fast neutron reactor and fusion reactor. As one of the polytypes, 4H-SiC has prospective important applications in a strong irradiation environment. In this work, molecular dynamics (MD) simulation was performed to study the irradiation-induced cascade damage in single-crystalline 4H-SiC to get the microscopic evolution during the irradiation, in the aim of getting access to the detail that we cannot get from experiments. The software LAMMPS was used to simulate the damage formation process and the recovery process. The results showed that the initial project direction, the temperature and PKA energy exerted significant effects on the number and morphology of defects. (authors)

  2. An introduction to the impact of self-irradiation on nuclear glasses

    International Nuclear Information System (INIS)

    Ghaleb, D.

    1997-01-01

    Irradiation is an important factor in the aging of glasses used to confine nuclear wastes. Beta decays are prevailing during the first 500 years then alpha decays take over. Alpha decay is the main cause of atomic displacements while beta decay, through the emission of energetic electrons, is responsible for most electronic excitations and ionization. Each alpha decay is followed by the creation of an helium atom trapped inside the bulk of glass. (A.C.)

  3. Self-irradiation of the blood from selected nuclides in nuclear medicine

    International Nuclear Information System (INIS)

    Hänscheid, H; Fernández, M; Eberlein, U; Lassmann, M

    2014-01-01

    Nuclear medicine dosimetry and research in biodosimetry often require the knowledge of the absorbed dose to the blood. This study provides coefficients for the absorbed dose rates to the blood related to the activity concentration in the blood as a function of the vessel radius for radionuclides commonly used in targeted radiotherapy and in PET-diagnostics: C-11, F-18, Ga-68, Y-90, Tc-99 m, I-124, I-131, and Lu-177. The energy deposition patterns after nuclear disintegrations in blood vessel lumina (cylinders homogeneously filled with blood) with radii from 0.01 to 25.0 mm were simulated with the Monte-Carlo radiation transport code MCNPX. An additional contribution from photon radiation from activity in blood in the remainder of the body was taken into account based on a reasonable blood distribution model. The fraction of energy absorbed from non-penetrating radiation in the blood is low in thin blood vessels but approaches the total energy emitted by particles with increasing lumen radius. For photon radiation, irradiation to blood in small vessels is almost completely due to radioactive decays in distant blood distributed throughout the body, whereas the contribution from activity in the vessel becomes dominant for lumen radii exceeding 13 mm. The dependences of the absorbed dose rates on the lumen radius can be described with good accuracy by empirical functions which can be used to determine the absorbed doses to the blood and to the surrounding tissue. (paper)

  4. Crystal orientation and sample preparation effects on sputtering and lattice damage in 100 keV self-irradiated copper

    International Nuclear Information System (INIS)

    Sprague, J.A.; Malmberg, P.R.; Reynolds, G.W.; Lambert, J.M.; Treado, P.A.; Vincenz, A.M.

    1987-01-01

    Sputtering yields and angular distributions have been measured as functions of sample preparation techniques and incident ion-beam orientation with respect to the crystal axes for 100 keV Cu-ion beams on Cu crystals and polycrystalline samples. The angular distributions have structure requiring an nth order cosine with two Gaussians superimposed to fit the data; strong peaking is observed near the backscatter direction. The yield is dependent on the beam to crystal and beam to polycrystalline-rod axis orientation, on the grain size of the polycrystals and on sample-preparation techniques. Yield measurements vary by as much as a factor of 4. Lattice-damage differences, measured with alpha particle channeling, are much smaller and seem to be saturated by fluences of the order of 1x10 16 /cm 2 . (orig.)

  5. Understanding the effects of alpha self-irradiation on the glass structure by coupling spectroscopic studies and atomistic modeling

    International Nuclear Information System (INIS)

    Bureau, G.

    2008-12-01

    Our objective was to assess irradiation effects on nuclear containment glass in order to guarantee glass performance when subjected to high alpha decay doses. Experimental studies and molecular dynamics modeling provided a better understanding of the impact of cumulative alpha decay on the structural behavior of complex nuclear glass formulations and of simplified glass models. A mechanism typical of sodium borosilicate glass was identified in response to nuclear interactions or ballistic collisions. The glass local order is slightly modified by the conversion of a fraction of the boron atoms from coordination number IV to III, releasing charge-compensating alkali ions that become available as network modifiers, and resulting in a slight increase in the number of non bridging oxygen atoms. The medium-range order shifts toward increasing disorder in the glass as indicated by broadening of the angular, radial, and size distributions. A model of accumulated quasi-thermal quenching is proposed to account for these changes, based on the two steps describing the reaction of the glass to the alpha decay recoil nucleus: a cascade generates a ballistic phase that completely destabilizes the glass structure with no short and medium-range order, resulting in the loss of the initial structure; glass reconstruction is controlled only by the 'quenching rate' in the displacement cascade, i.e. by its thermal history and the corresponding relaxation options. From this standpoint the final glass structure is the consequence of the ballistic changes and the regenerative capacity of the glass structure, resulting in a higher fictive-temperature glass corresponding to the structural changes identified in this study. (author)

  6. Crystallographic study and self irradiation damage on plutonium at low temperature; Etude cristallographique et effets de l'auto-irradiation sur le plutonium a basse temperature

    Energy Technology Data Exchange (ETDEWEB)

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

    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)

  7. Thermal neutron detection by activation of CaSO4:Dy + KBr thermoluminescent phosphors

    International Nuclear Information System (INIS)

    Gordon, A.M.P.L.; Muccillo, R.

    1979-01-01

    Thermoluminescence (TL) studies to detect thermal neutrons were performed in cold-pressed CaSO 4 :0,1%Dy + KBr samples. The detection is based on the self-irradiation of the CaSO 4 :Dy TL phosphor by the Br isotopes activated by exposure to a mixed neutron-gamma field. (Author) [pt

  8. Effects of irradiation on structural properties of crystalline ceramics

    International Nuclear Information System (INIS)

    Clinard, F.W. Jr.; Hurley, G.F.

    1979-01-01

    Stability of crystalline ceramic nuclear waste may be degraded by self-irradiation damage. Changes in density, strength, thermal conductivity, and lattice structure are of concern. Structural damage of ceramics under various radiation conditions is discussed and related to possible effects in nuclear waste

  9. Effects of irradiation on structural properties of crystalline ceramics

    International Nuclear Information System (INIS)

    Clinard, F.W. Jr.; Hurley, G.F.

    1979-01-01

    Stability of crystalline ceramic nuclear waste may be degraded by self-irradiation damage. Changes in density, strength, thermal conductivity, and lattice structure are of concern. In this paper, structural damage of ceramics under various radiation conditions is discussed and related to possible effects in nuclear waste

  10. Kinetics of the oxidation-reduction reactions of uranium, neptunium, plutonium, and americium in aqueous solutions

    International Nuclear Information System (INIS)

    Newton, T.W.

    1975-01-01

    This is a review with about 250 references. Data for 240 reactions are cataloged and quantitative activation parameters are tabulated for 79 of these. Some empirical correlations are given. Twelve typical reactions are discussed in detail, along with the effects of self-irradiation and ionic strength. (U.S.)

  11. Neutron diffraction study of δ-alloy Pu{sup 242}–Ga aging

    Energy Technology Data Exchange (ETDEWEB)

    Somenkov, V.A. [National Research Center “Kurchatov Institute”, Moscow (Russian Federation); Blanter, M.S., E-mail: mike.blanter@gmail.com [Moscow State University of Instrumental Engineering and Information Science, Moscow (Russian Federation); Glazkov, V.P. [National Research Center “Kurchatov Institute”, Moscow (Russian Federation); Laushkin, A.V.; Orlov, V.K. [JSC VNIINM n.a. A.A. Bochvar, Moscow (Russian Federation)

    2014-09-15

    In this paper, we report on a continuing neutron diffraction study of the mean-square atom displacements occurring during the long-term self-irradiation of a Pu–Ga alloy. The measurements were performed at room temperature using the sample based on the isotope Pu{sup 242} with low neutron absorption cross-section to which the short-lived isotope Pu{sup 238} (1.4 wt.%) was added to accelerate self-irradiation. We obtain the maximum self-irradiation equivalent time of 35.5 years, 12 years longer than in our previous papers. In the entire range of self-irradiation time a single fcc phase is preserved. It was found that after the two stages of change in the mean-square displacements we observed earlier (rapid growth up to ∼5–6 equivalent years and a slow decline in the range of ∼6–25 years), comes a stage of stabilization (after ∼25 years). The stabilization can be explained by the emergence of a balance between the formation of point defects and their absorption by helium bubbles and dislocation loops which accumulated over time.

  12. Radiation damage in gallium-stabilized δ-plutonium with helium bubbles

    Energy Technology Data Exchange (ETDEWEB)

    Wu, FengChao [CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, University of Science and Technology of China, Hefei, Anhui 230027 (China); Wang, Pei [Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China); Liu, XiaoYi [CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, University of Science and Technology of China, Hefei, Anhui 230027 (China); Wu, HengAn, E-mail: wuha@ustc.edu.cn [CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, University of Science and Technology of China, Hefei, Anhui 230027 (China)

    2017-02-15

    To understand the role of helium on self-irradiation effects in δ-plutonium, microstructure evolutions due to α-decay events near pre-existing helium bubbles in gallium-stabilized δ-plutonium are investigated using molecular dynamics simulations. Bubble promoting effect plays a dominating role in point defects production, resulting in increasing number of point defects. When lightweight helium atoms act as media, energy transfer discrepancy and altered spatial morphology of point defects induced by mass effect are revealed. The evolution of stacking faults surrounding the disordered core is studied and their binding effect on the propagation of point defects are presented. The cascade-induced bubble coalescence, resolution and re-nucleation driven by internal pressure are obtained in the investigation on helium behaviors. The intrinsic tendency in our simulated self-irradiation with helium bubbles is significant for understanding the underlying mechanism of aging in plutonium and its alloys.

  13. Synthesis document on the long time behavior of packages: operational document ''bituminous'' 2204

    International Nuclear Information System (INIS)

    Tiffreau, C.

    2004-09-01

    This document is realized in the framework of the law of 1991 on the radioactive wastes management. The 2004 synthesis document on long time behavior of bituminous sludges packages is constituted by two documents, the reference document and the operational document. This paper presents the operational model describing the water alteration of the packages and the associated radioelements release, as the gas term source and the swelling associated to the self-irradiation and the bituminous radiolysis. (A.L.B.)

  14. Zirconium molybdate gel as a generator for technetium-99m

    International Nuclear Information System (INIS)

    Evans, J.V.; Shying, M.E.

    1984-12-01

    A new sup(99m)Tc generator based on zirconium molybdate gel is described. Essentially the gel is a cation ion exchanger which permits the elution of the pertechnetate ion. The high molybdenum content of this gel, its stability under self-irradiation, and the absence of organic materials during preparation provide a generator concept that eliminates high processing costs, active waste storage costs and stability problems in other types of generator

  15. Mass transfer in silicon at deposition of Ti thin films assisted by self ion irradiation

    International Nuclear Information System (INIS)

    Mikhalkovich, O.M.; Tashlykov, I.S.; Gusakov, V.E.

    2011-01-01

    In this paper a composite structure, processes of diffusion in Si, modified by means of ion-assisted deposition of coatings in conditions of a self-irradiation are discussed. Rutherford backscattering in combination with a channelling (RBS/Ch) of He + ions and computer program RUMP were applied to investigate an element composition. It is established, that coatings include atoms of metal, hydrogen, carbon, oxygen, silicon. The interstitial Si atoms, generated by radiation effect, diffuse during deposition of thin coating, both in a depth of a wafers, and in coatings. The influence of irradiation of ions Xe+ on diffusion processes in silicon are revealed. (authors)

  16. Application of radiophotoluminescence dosemeters for environmental monitoring

    International Nuclear Information System (INIS)

    Mihara, A.; Tamura, T.; Mochizuki, T.; Numakunai, T.; Yoshida, Y.; Ohi, Y.

    1993-01-01

    Feasibility study has been made on the radiofluorescence glass (RPL) dosemeters for environmental radiation monitoring. Main items in the laboratory tests are batch uniformities of pre-dose and sensitivity, build-up characteristics of RPL intensity, energy and angular responses, stabilities for RPL reading, anneal cycling and climatic conditional changes. We have determined self-irradiation dose and cosmic ray contribution. Radiation monitoring field test for the RPL dosemeters has been conducted in comparison with the present TLD systems. A procedure manual for the environmental monitoring by the use of RPL dosemeters is in preparation

  17. LINE FORMATION IN SPECTRA OF X-RAY NOVAE

    OpenAIRE

    Suleimanov, V. F.; Shimansky, V. V.

    2017-01-01

    Results of X-ray Novae (XN) optical spectra computation are presented. The continuum and Balmer line are calculated. The model of XN as a self-irradiated accretion disk is used. Local (for given radius) disk atmospheres as model stellar atmospheres, heated due to external X-ray radiation are treated. Changes of spectra shape and equivalent widths of the Balmer lines depending from the luminosity and some others accretion disk parameters are investigated. The comparison of GRO JO422+32 observe...

  18. Experimental hydrothermal alteration of crystalline and radiation-damaged pyrochlore

    International Nuclear Information System (INIS)

    Geisler, T.; Seydoux-Guillaume, A.-M.; Poeml, P.; Golla-Schindler, U.; Berndt, J.; Wirth, R.; Pollok, K.; Janssen, A.; Putnis, A.

    2005-01-01

    We have performed hydrothermal experiments with a crystalline microlite and a heavily self-irradiation-damaged (i.e., X-ray amorphous) betafite in a solution containing 1 mol/l HCl and 1 mol/l CaCl 2 at 175 deg. C for 14 days. The well-crystalline microlite grains were partly (∼5-10 μm rim) replaced by a Ca and Na-poorer, defect pyrochlore phase with a larger unit-cell and a sharp chemical gradient at the interface (on a nm scale) to the unreacted core. The amorphous betafite grains (up to ∼2 mm in diameter), on the other hand, were completely transformed into an intergrowth of different crystalline phases (polycrystalline anatase and rutile, a yet unidentified Nb-Ta oxide, and a Y-REE phase), showing complex non-equilibrium structures. Our experimental observations bear a remarkable resemblance to those made on natural samples. They indicate that the processes of the fluid-pyrochlore interaction are influenced by self-irradiation structural damage and that thermodynamic equilibrium models can hardly be applied to adequately describe such systems

  19. Anomalous diffusion in body-centred and face-centred cubic metals

    International Nuclear Information System (INIS)

    Zanghi, J.-P.

    1975-10-01

    The initial rates of contraction due to self-irradiation damage at 4.2K in three PuSc alloys (5, 12, 18 at % Sc) stabilized in f.c.c. delta-phase were measured. The high negative value of the formation volume of a Frenkel pair which is deduced by extrapolating for pure Pu, can only be explained by assuming that the interstitial Pu may partly recover its distortion energy by creating bonds with its neighbours, by a localized enhancement of the d.f. hybridization and especially by provoking the formation of bonds between its very neighbours. It is shown that about twenty atoms around the interstitial Pu are affected by these bonds. The self-irradiation at 4.2K of a b.c.c. UPuMo alloy was also studied. The activation volume for self-diffusion of Pu in b.c.c. PuZr alloys (10 and 40 at % Zr) was determined. So the validity of Nachtrieb's melting-diffusion correlation could be checked. Indeed, in the Pu 40 at % Zr alloy, which has a pressure temperature diagram the liquidus of which has a positive slope, a positive activation volume was found, whereas in pure epsilon Pu which as a negative slope, the activation volume is negative. A self-diffusion mechanism in PuZr alloys is proposed. A study of the diffusion of Am in these alloys showed that Am and Pu likely diffuse by the same mechanism [fr

  20. Raman study of radiation-damaged zircon under hydrostatic compression

    Science.gov (United States)

    Nasdala, Lutz; Miletich, Ronald; Ruschel, Katja; Váczi, Tamás

    2008-12-01

    Pressure-induced changes of Raman band parameters of four natural, gem-quality zircon samples with different degrees of self-irradiation damage, and synthetic ZrSiO4 without radiation damage, have been studied under hydrostatic compression in a diamond anvil cell up to ~10 GPa. Radiation-damaged zircon shows similar up-shifts of internal SiO4 stretching modes at elevated pressures as non-damaged ZrSiO4. Only minor changes of band-widths were observed in all cases. This makes it possible to estimate the degree of radiation damage from the width of the ν3(SiO4) band of zircon inclusions in situ, almost independent from potential “fossilized pressures” or compressive strain acting on the inclusions. An application is the non-destructive analysis of gemstones such as corundum or spinel: broadened Raman bands are a reliable indicator of self-irradiation damage in zircon inclusions, whose presence allows one to exclude artificial color enhancement by high-temperature treatment of the specimen.

  1. Minerals and design of new waste forms for conditioning nuclear waste; Les mineraux et la formulation de nouvelles matrices de stockage pour les dechets radioactifs

    Energy Technology Data Exchange (ETDEWEB)

    Montel, J.M. [G2R, CNRS, Ecole nationale superieure de geologie, Nancy-universite, BP 70239, 54056 Vandoeuvre-les-Nancy (France)

    2011-02-15

    Safe storage of radioactive waste is a major challenge for the nuclear industry. Mineralogy is a good basis for designing ceramics, which could eventually replace nuclear glasses. This requires a new storage concept: separation-conditioning. Basic rules of crystal chemistry allow one to select the most suitable structures and natural occurrences allow assessing the long-term performance of ceramics in a geological environment. Three criteria are of special interest: compatibility with geological environment, resistance to natural fluids, and effects of self-irradiation. If mineralogical information is efficient for predicting the behaviour of common, well-known minerals, such as zircon, monazite or apatite, more research is needed to rationalize the long-term behaviour of uncommon waste form analogs. (author)

  2. Effective dose due to environmental γ-ray for the people of Akita prefecture

    International Nuclear Information System (INIS)

    Yamashita, Junsuke; Watarai, Jiro; Hisamatsu, Shun'ichi

    2001-01-01

    Environmental γ-ray doses were measured in Akita prefecture by a NaI(Tl) scintillation surveymeter. The numbers of measurement site were 207 on pavement, 45 on unpaved ground, nine in concrete buildings and nine in wooden houses. The results of measurements, which were subtracted for background (cosmic ray and self-irradiation of the surveymeter), were 31 nSv/h (effective dose rate) on pavement, 27 nSv/h on unpaved ground, 65 nSv/h in the concrete buildings and 34 nSv/h in the wooden houses. The effective dose rate due to environmental γ-ray for the people of Akita prefecture was estimated taking into account of seasonal change of the dose rate at one site and occupancy factor in the prefecture. The outdoor and indoor dose rates were estimated to be 0.03 mSv/y and 0.33 mSv/y, respectively. (author)

  3. Behaviour of bituminized radioactive wastes under irradiation

    International Nuclear Information System (INIS)

    Camaro, S.; Gilardi, T.; Vistoli, P.P.

    2000-01-01

    Studies are carried out by the CEA in order to predict the behaviour of bituminized radioactive wastes under self irradiation. Bitumen radiolysis produces gas (mainly H 2 ) which diffuses in the organic matrix. If the hydrogen yield is higher than the diffusion flux through the free surface, hydrogen concentration increases and exceeds its solubility in bitumen. Beyond saturation, bubbles are formed and gas is also evacuated by bubbles drift. The aim of these studies is to evaluate the evacuation capacity of radiolytic gas produced in function of initial bituminized wasteform characteristics. A model was developed to achieve this purpose, by calculating the evolution of bubbles population considering all elementary mechanisms of gas evacuation. (authors)

  4. Minerals and design of new waste forms for conditioning nuclear waste

    Science.gov (United States)

    Montel, Jean-Marc

    2011-02-01

    Safe storage of radioactive waste is a major challenge for the nuclear industry. Mineralogy is a good basis for designing ceramics, which could eventually replace nuclear glasses. This requires a new storage concept: separation-conditioning. Basic rules of crystal chemistry allow one to select the most suitable structures and natural occurrences allow assessing the long-term performance of ceramics in a geological environment. Three criteria are of special interest: compatibility with geological environment, resistance to natural fluids, and effects of self-irradiation. If mineralogical information is efficient for predicting the behaviour of common, well-known minerals, such as zircon, monazite or apatite, more research is needed to rationalize the long-term behaviour of uncommon waste form analogs.

  5. The effect of gamma irradiation on the stability of cemented Winfrith reactor (SGHWR) sludge

    International Nuclear Information System (INIS)

    Holland, T.R.

    1985-01-01

    The effects of prolonged self-irradiation within cemented Winfrith SGHWR sludge have been investigated by exposing simulant material to a CO-60 source. Measurements of dimensional stability and radiolysis have been used in this assessment of radiation stability. The dimensional stability of the cement matrix was unaffected by an irradiation intensity which greatly exceeded the expected lifetime dose, and radiolysis rates have followed those which have previously been observed by other researchers. Data obtained for the release of radiolytic hydrogen has allowed a prediction to be made of release from the full-size product, during decay of the principal radioactive species, Co-60. A method has been developed for the determination of dimensional stability using non-standard sized specimens and is appended. (author)

  6. Electron Elevator: Excitations across the Band Gap via a Dynamical Gap State.

    Science.gov (United States)

    Lim, A; Foulkes, W M C; Horsfield, A P; Mason, D R; Schleife, A; Draeger, E W; Correa, A A

    2016-01-29

    We use time-dependent density functional theory to study self-irradiated Si. We calculate the electronic stopping power of Si in Si by evaluating the energy transferred to the electrons per unit path length by an ion of kinetic energy from 1 eV to 100 keV moving through the host. Electronic stopping is found to be significant below the threshold velocity normally identified with transitions across the band gap. A structured crossover at low velocity exists in place of a hard threshold. An analysis of the time dependence of the transition rates using coupled linear rate equations enables one of the excitation mechanisms to be clearly identified: a defect state induced in the gap by the moving ion acts like an elevator and carries electrons across the band gap.

  7. A photoionization model for the optical line emission from cooling flows

    Science.gov (United States)

    Donahue, Megan; Voit, G. M.

    1991-01-01

    The detailed predictions of a photoionization model previously outlined in Voit and Donahue (1990) to explain the optical line emission associated with cooling flows in X-ray emitting clusters of galaxies are presented. In this model, EUV/soft X-ray radiation from condensing gas photoionizes clouds that have already cooled. The energetics and specific consequences of such a model, as compared to other models put forth in the literature is discussed. Also discussed are the consequences of magnetic fields and cloud-cloud shielding. The results illustrate how varying the individual column densities of the ionized clouds can reproduce the range of line ratios observed and strongly suggest that the emission-line nebulae are self-irradiated condensing regions at the centers of cooling flows.

  8. Physical-chemical studies of transuranium elements: Progress report for the period April 1, 1985-March 31, 1988

    International Nuclear Information System (INIS)

    Peterson, J.R.

    1987-01-01

    New knowledge is being accumulated in the role of the 5f electrons in the bonding in actinide elements and compounds, the relationships of metallic structures to metallic valence and radius, the extent and magnitude of the actinide contraction, the magnetic, thermodynamic, spectroscopic, and crystallographic properties of these materials as related to general theories, the effect of self-irradiation on chemical and physical properties, the chemical and physical consequences of radioactive decay in the bulk-phase solid state, and in general, the range of validity of the actinide hypothesis. Separate reports are given on: spectrophotometric studies of Cf(III) ions in lanthanide trihalide hosts, new ternary transplutonium chalcogenide halides, Raman spectrometric studies of lanthanide trihalides as function of T or P, and solution calorimetry of californium halides

  9. Auto-regenerative thermoluminescence dating using zircon inclusions

    International Nuclear Information System (INIS)

    Templer, R.H.

    1993-01-01

    Fired ceramics containing zircon inclusions have been dated by allowing the zircons to regenerate their own thermoluminescence (TL) signal, hence auto-regenerative TL dating. The technique is conceptually straightforward. One first measures the TL accrued since the last heating of the material. The zircon grains are then stored for six months and the TL signal regenerated through self-irradiation is measured. Since the internal dose-rate for zircon is dominated by the internal component the age of the sample is simply given by the ratio of the natural to auto-regenerated signal times the laboratory storage period. The technique, however, requires the measurement of a very small auto-regenerated signal, which introduces a number of experimental and physical complications. The methods for overcoming these problems and successfully dating zircons by auto-regeneration are described. (Author)

  10. Gamma-X-ray coincidence Moessbauer spectroscopic study of the aftereffects in sulfate hydrates

    International Nuclear Information System (INIS)

    Kobayashi, T.; Makita, T.; Fukumura, K.

    1990-01-01

    The anomalous charge states formed after the electron capture decay of 57 Co in FeSO 4 .H 2 O and FeSO 4 .7H 2 O are investigated using the conventional Moessbauer emission spectroscopy and a gamma-X ray coincidence method. This method is based on the idea that a Moessbauer spectrum observed with the coincidence technique only when K-X rays are emitted is reflected by isolated events with a reduced influence of the Auger-electron self-irradiation. The formation of the anomalous electronic and structural configuration is attributed to the self-radiolysis of the H 2 O and SO 4 2- ligands in the nearest and the second nearest coordination shells around the decaying atom. (orig.)

  11. Studies of high-level radioactive waste form performance at Japan Atomic Energy Research Institute

    International Nuclear Information System (INIS)

    Banba, Tsunetaka; Kamizono, Hiroshi; Mitamura, Hisayoshi

    1992-02-01

    The recent studies of high-level radioactive waste form at Japan Atomic Energy Research Institute can be classified into the following three categories; (1) Study on the leaching behavior of the nuclear waste glass placing the focus on the alteration layer and the chemical composition of leachant for the prediction of the long-term corrosion of the waste glass. (2) Study on the radiation (alpha-radiation) effects which have relation to the long-term stability of the nuclear waste glass. (3) Study on the long-term self-irradiation damage of a SYNROC waste form using a curium-doped sample. In the present report, the recent results corresponding to the above categories are described. (author)

  12. Behavior of radioisotope in liquid neutron irradiated Pb-17Li eutectic

    International Nuclear Information System (INIS)

    Tebus, V.N.; Aksenov, B.S.; Klabukov, U.G.

    1994-01-01

    Investigation of radioisotope 210 Po evaporation from liquid neutron irradiated Pb- 17 Li eutectic has been performed by Knudsen method. Equilibrium 210 Po vapor pressures at temperatures 250-700 degrees C were found about 3-4 orders of magnitude less than that for pure Po and were closed to equilibrium vapor pressures of Po-Pb compound. It was proposed Po forms stable Po-Pb compounds in eutectic at temperatures up to 750-800 degrees C. But disintegrates during long storage owing to self irradiation. It was determined Po aerosol transfer with radio gases takes place at the melting period. Contamination is happened also under irradiated eutectic storage at room temperature owing to aggregate recoil characteristic of Po

  13. Measurement of thermal neutron fluence with CaSO4 thermoluminescent phosphors

    International Nuclear Information System (INIS)

    Liu Jinhua; Su Jingling; Wei Zemin

    1984-01-01

    During neutron irradiation, some TL phosphors were activated. After leaving the irradiation field the TL phosphor produced self-irradiation. The TL output of self-dose was only related to the original neutron fluence and independent of the γ-radiation. Several CaSO 4 TL phosphors were made. They were CaSO 4 :Dy, CaSO 4 :Dy-Teflon, CaSO 4 :Dy mixed with Dy 2 O 3 , CaSO 4 :Mn mixed with Dy 2 O 3 . The linearity, and lower detection limits of these TL phosphors were measured. The thermal neutron response of CaSO 4 :Mn mixed with Dy 2 O 3 was 64 R/(10 10 cm -2 ) and the lower detection limit was 1.3x10 5 cm -2

  14. Study of thermoluminescence emissions of dosimetric phosphors; the detection of intermediate neutrons

    International Nuclear Information System (INIS)

    Santos, E.N. dos.

    1979-01-01

    Thermally stimulated luminescence (TSL) studies have been carried out in cold-pressed CaSO 4 +DY 2 O 3 +KCl (specimen 1) and natural CaF 2 +DY 2 O 3 + KCl (specimen 2) polycrystaline samples. The ratios of the TSL sensivities of specimens 1 and 2 relative to that of 6 LiF:Mg;Ti (TLD-600) are found to be 24 and 3, respectively. The minimum detectable neutron fluence has been determined to be approximately 3.5X10 5 n/cm 2 . The determination of the effective half-life of the TSL emission lead to the identification of the isotope responsible for the self-irradiation of the specimens: 165 66 DY. (F.E.) [pt

  15. What fits best minor actinides as a die material?

    International Nuclear Information System (INIS)

    Hinfray, J.

    2003-01-01

    Zirconolite might be the die material used to confine actinides definitively. Cea's teams have been investigating the ability of zirconolite to trap actinide atoms in its own crystal structure. These studies have been performed with 239 Pu that presents the same ability to set chemical links with the constituents of the die as 3 minor actinides do. Crystal materials like zirconolite are more sensitive to self irradiation than glass. The next step of the characterization of zirconolite is to evaluate its capacity to sustain self alpha irradiation. In order to do so, 238 Pu is used since its relatively short period (T = 87 years) allows an acceleration of the process : damages cumulated in the die material in 2 years will be equivalent to those produced by minor actinides for millions years. The results will be known in 2004. (A.C.)

  16. A study of accelerated radiation damage effects in PuO{sub 2} and gadolinia-stabilized cubic zirconia, Zr{sub 0.79}Gd{sub 0.14}Pu{sub 0.07}O{sub 1.93}, doped with {sup 238}Pu

    Energy Technology Data Exchange (ETDEWEB)

    Burakov, B.E., E-mail: burakov@peterlink.ru [V.G. Khlopin Radium Institute, 28, 2-nd Murinskiy Ave., St. Petersburg, 194021 (Russian Federation); Yagovkina, M.A. [A.F. Ioffe Physical-Technical Institute, 26, Politekhnicheskaya, St. Petersburg, 194021 (Russian Federation)

    2015-12-15

    Polycrystalline samples of cubic zirconia, Zr{sub 0.79}Gd{sub 0.14}Pu{sub 0.07}O{sub 1.93}, doped with approximately 9.9 wt.% {sup 238}Pu, and PuO{sub 2} containing 11.0 wt. % {sup 238}Pu (and main isotope is {sup 239}Pu) have been repeatedly studied during many years by X-ray diffraction analysis. At a temperature of 25 °C the unit-cell parameter of PuO{sub 2} increases depending on accumulated dose, and is accompanied by decrease of coherent scattering region (CSR). Self-irradiation of Zr{sub 0.79}Gd{sub 0.14}Pu{sub 0.07}O{sub 1.93} is accompanied with repeated change of unit-cell parameter and CSR.

  17. Evaluation of BICRON NE MCP DXT-RAD passive extremity dosemeter

    CERN Document Server

    Yuen, P S; Frketich, G; Rotunda, J

    1999-01-01

    Passive extremity dosemeters currently used in dosimetry communities worldwide have shortcomings. In general, an extremity dosemeter has too thick a detector element, and the dosemeter response is highly energy dependent for beta rays with energies ranging from 200 keV to 2 MeV. It often does not have dosemeter identification, causing problems in the chain of custody. It is often read manually, rendering reading/packing operations very labour intensive. As a result of collaboration between AECL and BICRON NE, a new extremity dosemeter, incorporating a highly sensitive LiF:Mg,Cu,P TLD and tentatively code named MCP DXT-RAD, was developed. It has been evaluated for radiological performance against an ISO draft standard for extremity dosemeters in twelve categories: homogeneity, detection threshold, beta ray energy response, beta angular response, photon energy response, photon angular response, reproducibility, stability under various climatic conditions, linearity, residue, self irradiation, and effect of ligh...

  18. Thermal conductivity of (Np0.20Pu0.50Am0.25Cm0.05)O2−x solid solutions

    International Nuclear Information System (INIS)

    Nishi, Tsuyoshi; Takano, Masahide; Akabori, Mitsuo; Arai, Yasuo

    2013-01-01

    Highlights: • Thermal conductivity of (Np 0.20 Pu 0.50 Am 0.25 Cm 0.05 )O 2−x was evaluated. • Dependence of thermal conductivity on storage time was clarified. • Results were discussed with the lattice expansion model by self-irradiation. • After annealing at 1423 K in vacuum, thermal conductivity returned. -- Abstract: The authors prepared the sintered sample of (Np 0.20 Pu 0.50 Am 0.25 Cm 0.05 )O 2−x (2 − x = 1.98, 1.96) solid solution and evaluated the dependence of the thermal conductivity on storage time and temperature. The heat capacity of (Np 0.20 Pu 0.50 Am 0.25 Cm 0.05 )O 1.98 was measured between 324 and 1082 K by a drop calorimetry. The thermal diffusivity of (Np 0.20 Pu 0.50 Am 0.25 Cm 0.05 )O 1.98 was measured when the storage time became 48, 216, 720 and 1584 h and that of (Np 0.20 Pu 0.50 Am 0.25 Cm 0.05 )O 1.96 was measured when the storage time became 0,528 and 1386 h. In this study, the latter sample was annealed at 1423 K in vacuum with background pressure of less than 2.0 × 10 −4 Pa just after the measurement on the storage time, 1386 h. The thermal diffusivity of (Np 0.20 Pu 0.50 Am 0.25 Cm 0.05 )O 1.96 just after annealing returned to the values of the storage time, 0 h. This result reveals the thermal recovery behavior by annealing. The thermal conductivity of (Np 0.20 Pu 0.50 Am 0.25 Cm 0.05 )O 2−x was determined from the measured thermal diffusivity, heat capacity and bulk density. The thermal conductivity of (Np 0.20 Pu 0.50 Am 0.25 Cm 0.05 )O 2−x exponentially decreased with increasing storage time. This result suggested that the decrease of the thermal conductivity was attributed to the accumulation of lattice defects caused by self-irradiation

  19. Comparison of internal dose estimates obtained using organ-level, voxel S value, and Monte Carlo techniques

    Energy Technology Data Exchange (ETDEWEB)

    Grimes, Joshua, E-mail: grimes.joshua@mayo.edu [Department of Physics and Astronomy, University of British Columbia, Vancouver V5Z 1L8 (Canada); Celler, Anna [Department of Radiology, University of British Columbia, Vancouver V5Z 1L8 (Canada)

    2014-09-15

    Purpose: The authors’ objective was to compare internal dose estimates obtained using the Organ Level Dose Assessment with Exponential Modeling (OLINDA/EXM) software, the voxel S value technique, and Monte Carlo simulation. Monte Carlo dose estimates were used as the reference standard to assess the impact of patient-specific anatomy on the final dose estimate. Methods: Six patients injected with{sup 99m}Tc-hydrazinonicotinamide-Tyr{sup 3}-octreotide were included in this study. A hybrid planar/SPECT imaging protocol was used to estimate {sup 99m}Tc time-integrated activity coefficients (TIACs) for kidneys, liver, spleen, and tumors. Additionally, TIACs were predicted for {sup 131}I, {sup 177}Lu, and {sup 90}Y assuming the same biological half-lives as the {sup 99m}Tc labeled tracer. The TIACs were used as input for OLINDA/EXM for organ-level dose calculation and voxel level dosimetry was performed using the voxel S value method and Monte Carlo simulation. Dose estimates for {sup 99m}Tc, {sup 131}I, {sup 177}Lu, and {sup 90}Y distributions were evaluated by comparing (i) organ-level S values corresponding to each method, (ii) total tumor and organ doses, (iii) differences in right and left kidney doses, and (iv) voxelized dose distributions calculated by Monte Carlo and the voxel S value technique. Results: The S values for all investigated radionuclides used by OLINDA/EXM and the corresponding patient-specific S values calculated by Monte Carlo agreed within 2.3% on average for self-irradiation, and differed by as much as 105% for cross-organ irradiation. Total organ doses calculated by OLINDA/EXM and the voxel S value technique agreed with Monte Carlo results within approximately ±7%. Differences between right and left kidney doses determined by Monte Carlo were as high as 73%. Comparison of the Monte Carlo and voxel S value dose distributions showed that each method produced similar dose volume histograms with a minimum dose covering 90% of the volume (D90

  20. Field lysimeter investigations: Low-level waste data base development program for fiscal year 1995. Volume 8, Annual report, October 1994-- September 1995

    International Nuclear Information System (INIS)

    McConnell, J.W. Jr.; Rogers, R.D.; Larsen, I.L.; Jastrow, J.D.; Sanford, W.E.; Sullivan, T.M.

    1996-06-01

    The Field Lysimeter Investigations: Low-Level Waste Data Base Development Program, funded by the U.S. Nuclear Regulatory Commission, is (a) studying the degradation effects in organic ion-exchange resins caused by radiation, (b) examining the adequacy of test procedures recommended in the Branch Technical Position on Waste Form to meet the requirements of 10 CFR 61 using solidified ion-exchange resins, (c) obtaining performance information on solidified ion- exchange resins in a disposal environment, and (d) determining the condition of liners used to dispose the ion-exchange resins. Compressive test results of 12-year-old cement and vinyl ester- styrene solidified waste form samples are presented, which show effects of aging and self-irradiation. Results of the tenth year of data acquisition from the field testing are presented and discussed. During the continuing field testing, both portland type I-II cement and Dow vinyl ester-styrene waste form samples are being tested in lysimeter arrays located at Argonne National Laboratory-East in Illinois and at Oak Ridge National Laboratory. The study is designed to provide continuous data on nuclide release and movement, as well as environmental conditions, over a 20-year period

  1. Thermal neutrons thermoluminescence dosimetry using CaF2 + KBr e CaSO4: Dy + Br

    International Nuclear Information System (INIS)

    Leite, A.M.P.

    1979-01-01

    Cold-pressed samples of CaF 2 + KBr and CaSO 4 :Dy + KBr have been used in the thermal neutron detection by the thermoluminescence technique. The amount of 100 mg of the TL phosphor added to 80 mg of KBr showed to be the optimum mixture regarding sensitivity as well as the handling of the dosimeters. The detection is based on the self-irradiation of the phosphor by the Br isotopes activated by exposure to a neutron-gama field. The prompt dose and consequentely the gama contribution are erased by post-irradiation thermal annealing. A linear dependence has been found between the TL self-induced signal and the thermal neutron flux in the range 10 6 n.cm -2 .seg -1 -10 -12 n.cm -2 .seg -1 . The minimum detectable fluence has benn determined as 10 9 n.cm -2 and 10 6 n.cm -2 using pellets of CaF 2 + KBr and CaSO 4 :Dy + KBr, respectively. The main results suggest the use of CaSO 4 :Dy + KBr pellets and TL as a complementary technique for thermal neutron detection. (author) [pt

  2. Spectrometric properties and radiation damage of BGO crystals

    Science.gov (United States)

    Kim, Gen C.; Gasanov, Eldar M.

    1997-07-01

    Spectrometric properties, such as light output, energy resolution BGO crystals before and after (superscript 60)Co gamma-ray (dose 10(superscript 4) - 10(superscript 6) R) and neutron irradiation (fluence 10(superscript 14) cm(superscript -2)) are investigated. Condition for degradation of spectrometric properties and their recovering after irradiation are studied. The energy spectrum of the photons emitted from BGO crystals irradiated with neutron fluence contains the long living background peak which is caused by self-irradiation with radioactive isotopes produced in the crystals. The defect production was studied in crystals under the high dose gamma-irradiation with (superscript 60)Co isotope. It was found that after doses above 10(superscript 8) R the color center at 365 nm and doses higher than 10(superscript 9) R a wide absorption band in the region of 300 - 350 nm occur. Comparison of these results with those of reactor irradiation has shown that under the high dose gamma-irradiation the structure defect production takes place.

  3. Neutron dosimetry using activation of thermoluminescent CaSO 4

    Science.gov (United States)

    Azorín, Juan; Gutiérrez, Alicia

    1984-11-01

    Sulfur activation in calcium sulfate doped with dysprosium (CaSO 4:Dy) thermoluminescent powder, which is bound in pure sulfur, has been used to measure the fast neutron dose at the tangential beam port of a Triga Mark III reactor. After a post-irradiation time of 3 d, the dosimeters were annealed at 600°C for 30 min in order to erase all the thermoluminescence acquired during the irradiation. The dosimeters were then stored to allow self-irradiation by betas from 32P produced by sulfur activation. The thermoluminescent signal accumulated during a post-irradiation time of 20 d due to a neutron fluence of 2.2 × 10 11 n/cm 2 was equivalent to an absorbed dose of 10 mGy of 60Co gamma rays. The thermoluminescence as a function of fast neutron dose fitted to a straight line on a log-log scale from 1 Gy to 10 4Gy.

  4. Observational evidence for gravitationally trapped massive axion(-like) particles

    CERN Document Server

    Di Lella, L

    2003-01-01

    Several unexpected astrophysical observations can be explained by gravitationally captured massive axions or axion-like particles, which are produced inside the Sun or other stars and are accumulated over cosmic times. Their radiative decay in solar outer space would give rise to a `self-irradiation' of the whole star, providing the time-independent component of the corona heating source (we do not address here the flaring Sun). In analogy with the Sun-irradiated Earth atmosphere, the temperature and density gradient in the corona$-$chromosphere transition region is suggestive for an omnipresent irradiation of the Sun, which is the strongest evidence for the generic axion-like scenario. The same mechanism is compatible with phenomena like the solar wind, the X-rays from the dark-side of the Moon, the X-Ray Background Radiation, the diffuse X-ray excesses (below $\\sim 1$ keV), the non-cooling of oldest Stars, etc. A temperature of $\\sim 10^6$ K is observed in various places, while the radiative decay of a popu...

  5. Thermoluminescent dose measurements on board Salyut type orbital stations

    International Nuclear Information System (INIS)

    Akatov, Yu.A.; Arkhangelskij, V.V.; Aleksandrov, A.P.

    1984-06-01

    A small, vibration- and shock-resistant thermoluminescent dosemeter (TLD) system - named PILLE - was developed for orbital stations at the Central Research Institute for Physics, Hungary, to measure the cosmic radiation dose on-board. The first on-board measurements with this system were performed by B. Farkas, the Hungarian astronaut, on the Salyut-6 space station in 1980. The same instrument was used by other crews in the following years. Doses measured at different sites in Salyut-6 are presented. The dose rates varied from 0.7 to 0.11 mGy.day -1 . After the first cosmic measurements, the system was further developed. The minimum detectable dose of the new TLD system is 1 μGy, i.e. less by one order of magnitude than that of the former system. The self-irradiation dose rate of the TLD bulbs is also reduced by more than an order of magnitude to 10 nGy.h -1 , by use of potassium-free glass for the bulb envelope. This new type of PILLE TLD system is currently on-board Salyut-7. The dose rates (0.12-0.23 mGy.day -1 ) measured in 1983 are presented in detail. (author)

  6. Radiation-induced microcrystal shape change as a mechanism of wasteform degradation

    Science.gov (United States)

    Ojovan, Michael I.; Burakov, Boris E.; Lee, William E.

    2018-04-01

    Experiments with actinide-containing insulating wasteforms such as devitrified glasses containing 244Cm, Ti-pyrochlore, single-phase La-monazite, Pu-monazite ceramics, Eu-monazite and zircon single crystals containing 238Pu indicate that mechanical self-irradiation-induced destruction may not reveal itself for many years (even decades). The mechanisms causing these slowly-occurring changes remain unknown therefore in addition to known mechanisms of wasteform degradation such as matrix swelling and loss of solid solution we have modelled the damaging effects of electrical fields induced by the decay of radionuclides in clusters embedded in a non-conducting matrix. Three effects were important: (i) electric breakdown; (ii) cluster shape change due to dipole interaction, and (iii) cluster shape change due to polarisation interaction. We reveal a critical size of radioactive clusters in non-conducting matrices so that the matrix material can be damaged if clusters are larger than this critical size. The most important parameters that control the matrix integrity are the radioactive cluster (inhomogeneity) size, specific radioactivity, and effective matrix electrical conductivity. We conclude that the wasteform should be as homogeneous as possible and even electrically conductive to avoid potential damage caused by electrical charges induced by radioactive decay.

  7. Irradiation effects in the storage and disposal of radioactive ion-exchange resins

    International Nuclear Information System (INIS)

    Swyler, K.J.; Dodge, C.E.; Dayal, R.; Weiss, A.J.

    1982-01-01

    Research is under way to characterize the effects of self-irradiation on radwastes which may be generated when organic ion-exchange media are used in water demineralization or decontamination operations at nuclear facilities. External factors affecting the relation between laboratory evaluations and field performance are emphasized. Initial experiments do not yet indicate substantial radiation dose-rate effects on radiolytic gas yields or acid product formation, when (fully swollen) sulfonic acid resins are irradiated in a sealed air environment. At the same time, oxygen gas is removed from the environment of irradiated resins. Interaction between mild steel coupons and acidic species produced in the irradiation induced decomposition of sulfonic acid resin results in irradiation enhanced corrosion. Corrosion rates depend on radiation dose rate, moisture content and resin chemical loading. In some cases, corrosion rates decrease with time, suggesting depletion of acidic species within the resin bed, or a synergistic interaction between resin and corrosion coupon. Implications of these and other results on evaluating field behavior of radwaste containing ion-exchange media are discussed. 4 figures, 2 tables

  8. Fundamental aspects of Am and Cm in zirconia-based materials. Investigations using X-ray diffraction and Raman spectroscopy

    International Nuclear Information System (INIS)

    Raison, P.E.; Haire, R.G.; Assefa, Z.

    2002-01-01

    We have investigated incorporation of americium and curium in selected zirconia-based materials. Fundamental aspects were explored via X-ray diffraction and Raman spectroscopy. First explored was the pseudo ternary system, AmO 2 -ZrO 2 -Y 2 O 3 . It was found that stable, cubic solid solutions (Am x Zr 1-x Y y )O 2-2/y can be obtained for selected compositions. The cell parameters of the cubic phases were established as being linear with the AmO 2 content. For the Cm 2 O 3 -ZrO 2 system, it was determined that diphasic materials are produced, except for two compositions: 25 mol% and 50 mol% of CmO 1.5 . For these compositions a single-phase cubic fluorite type solid solution (a=5.21A±0.01) and a pyrochlore oxide Cm 2 Zr 2 O 7 (a=10.63A±0.02) are formed, respectively. The stability of pyrochlore oxides is also being investigated as a function of self-irradiation, using shorter-lived isotopes, one being the californium pyrochlore 249 Cf 2 Zr 2 O 7 . We obtained evidence that after six months of storage the pyrochlore oxide is undergoing structural change. Additional studies are in progress. (author)

  9. Effects on auto-irradiation on the solubility of mineral phases enriched by actinides

    International Nuclear Information System (INIS)

    Prot, T.

    1993-07-01

    The scope of the present work is to investigate possible effects of self-irradiation damage induced by α-decay (α-recoil nucleus and α-particle) on the hydrated layer formed by aqueous corrosion of nuclear glass and on alteration phases of a granitic geological repository (calcium carbonate or iron oxides and oxihydroxide) which would be likely irradiated in the framework of high-level radioactive waste disposal, for sufficient concentration of actinides and age. Our experimental procedure relies on a bombardment with external beams of 1.5 to 1.8 MeV He ions and 200 KeV Pb ions, which respectively simulate the radiation effects of α-particles and of α-recoil nuclei. We have observed in a first step, direct irradiation effects (change of volume and refractive index, chemical modification) by means of optical microscopy, microtopographical analysis (surface profilometer) and R.B.S. and X.P.S. In a second step, corrosion tests were performed in static conditions to observe a possible indirect effect (increase of the hydratation rate, actinide release) on the later evolution as for example, a marked increase in solubility (calcium carbonate case)

  10. Rheological, structural and chemical evolution of bitumen under gamma irradiation

    International Nuclear Information System (INIS)

    Mouazen, M.; Poulesquen, A.; Bart, F.; Masson, J.; Charlot, M.; Vergnes, B.

    2013-01-01

    Bitumen derived from crude oil by fractional distillation has been used in the nuclear industry as a radioactive waste encapsulation matrix. When subjected to α, β and γ self-irradiation, this organic matrix undergoes radiolysis, generating hydrogen bubbles and modifying the physical and chemical properties of the material. In this paper, the effects of irradiation on bitumen materials, especially in terms of its physical, chemical, structural and rheological properties, were characterized at radiation doses ranging from 1 to 7 MGy. An increase in the shear viscosity and melt yield stress was observed with increasing doses. Similarly, the elastic and viscous moduli (G' and G'') increase with the dose, with a more pronounced increase for G' that reflects enhanced elasticity arising from radiation-induced cross-linking. In addition, a low-frequency plateau is observed for G', reflecting pseudo-solid behavior and leading to an increase of the complex viscosity. This behavior is due to increased interactions between asphaltene particles, and to aromatization of the bitumen by γ-radiations. Cross-linking of bitumen enhances its strength, as confirmed by various techniques (modulated DSC, DTA/TGA, SEC, FTIR and XRD). (authors)

  11. The mysterious world of plutonium metallurgy: Past and future

    International Nuclear Information System (INIS)

    Hecker, S.S.; Hammel, E.F.

    1998-01-01

    The first atomic bomb detonated at the Trinity Site in New Mexico on July 16, 1945, used plutonium, a man-made element discovered < 5 yr earlier. The story of how Manhattan Project scientists and engineers tackled the mysteries of this element and fabricated it into the first atomic bomb is one of the most fascinating in the history of metallurgy and materials. The authors are currently trying to generate renewed interest in plutonium metallurgy because of the challenge posed by President Clinton, i.e., to keep the nuclear stockpile of weapons safe and reliable without nuclear testing. The stockpile stewardship challenge requires either a lifetime extension of the plutonium components or a remanufacture--neither of which can be verified by testing. In turn, this requires that one achieve a better fundamental understanding of plutonium. Of special interest is the effect of self-irradiation on the properties and on the long-term stability of plutonium and its alloys. Additional challenges arise from long-term concerns about disposing of plutonium and dealing with its environmental legacy. It is imperative to interest the next generation of students in these plutonium challenges

  12. Charged defects during alpha-irradiation of actinide oxides as revealed by Raman and luminescence spectroscopy

    International Nuclear Information System (INIS)

    Mohun, R.; Desgranges, L.; Léchelle, J.; Simon, P.; Guimbretière, G.; Canizarès, A.; Duval, F.; Jegou, C.; Magnin, M.; Clavier, N.; Dacheux, N.; Valot, C.; Vauchy, R.

    2016-01-01

    We have recently evidenced an original Raman signature of alpha irradiation-induced defects in UO 2 . In this study, we aim to determine whether the same signature also exists in different actinide oxides, namely ThO 2 and PuO 2 . Sintered UO 2 and ThO 2 were initially irradiated with 21 MeV He 2+ ions using a cyclotron device and were subjected to an in situ luminescence experiment followed by Raman analysis. In addition, a PuO 2 sample which had accumulated self-irradiation damage due to alpha particles was investigated only by Raman measurement. Results obtained for the initially white ThO 2 showed that a blue color appeared in the irradiated areas as well as luminescence signals during irradiation. However, Raman spectroscopic analysis showed the absence of Raman signature in ThO 2 . In contrast, the irradiated UO 2 and PuO 2 confirmed the presence of the Raman signature but no luminescence peaks were observed. The proposed mechanism involves electronic defects in ThO 2 , while a coupling between electronic defects and phonons is required to explain the Raman spectra for UO 2 and PuO 2 .

  13. NUMERICAL INVESTIGATION OF THE COUPLED TURBULENT COMBUSTION-RADIATION IN AN

    Directory of Open Access Journals (Sweden)

    BRAHIM ZITOUNI

    2017-06-01

    Full Text Available A turbulent non-premixed methane-air flame was studied in an axisymmetric cylindrical combustion chamber, focusing on thermal radiation effects on temperature and soot concentration fields. The simulation is based on the solution of the mass, energy, momentum and chemical species conservation equations. The turbulence and its interaction with combustion are modelled by the standard k-ε model and eddy dissipation concept, respectively. The semiempirical model of Syed is implemented to deal with soot formation and oxidation and thus ensuring the overall efficiency of the present investigation. The radiative heat transfer is surveyed, for two cases: with and without soot radiation. The numerical resolution has been achieved using the Hottel’s zonal method and the standard weighted-sum-of-gray-gases model, to predict the real gas-soot mixture radiation effect. A new concept of optical exchange gap has been recently proposed and applied here after avoiding the singularities obviously encountered in the calculation of the direct exchange areas of volume zones self-irradiance. The obtained numerical results are compared to experimental data due to Brookes and Moss. Radiation exchange is found to noticeably affect temperature and soot volume fraction predictions and slightly the mixture fraction solutions. The present paper shows that taking into account turbulent combustion-radiation interactions leads to more accurate results by comparison to available experimental data.

  14. A moving target: responding to magnetic and structural disorder in lanthanide- and actinide-based superconductors

    International Nuclear Information System (INIS)

    Booth, Corwin H.; Bauer, Eric D.; Mitchel, Jeremy N.

    2010-01-01

    The effects of various chemical substitutions and induced lattice disorder in the Ce- and Pu-based 115 superconductors are reviewed, with particular emphasis on results from x-ray absorption fine structure (XAFS) measurements. The PuCoGa 5 system offers the opportunity to follow changes in magnetic and electronic properties due to lattice disorder as a function of time in the same samples, in addition to the more traditional approach of perturbing the superconducting state through chemical substitutions. The reviewed work establishes a baseline for such future studies by determining the intrinsic lattice order in the 115 system, successfully understanding disorder as introduced through chemical substitutions in the Ce-based 115s, and beginning to explore the surprisingly large role of self-irradiation damage directly on the PuCoGa 5 lattice. These studies lay the foundation for the harder future work toward measuring chemical substitutions in PuCoGa 5 , correlating effects with non-Fermi liquid behavior, and obtaining a better structural picture of the distortions induced by α-decay of the plutonium nucleus.

  15. Positron annihilation method for {alpha} self radiation effect studies in doped actinide UO{sub 2} samples

    Energy Technology Data Exchange (ETDEWEB)

    Roudil, D.; Vella, F.; Bonnal, M.; Broudic, V. [CEA centre de Marcoule. BP 17171 30207 Bagnols sur ceze cedex (France); Barthe, M.F.; Gentils, A.; Moineau, V. [CNRS- CEMHTI 3A rue de la Ferollerie 45071 Orleans Cedex (France); Jolly, L. [CEA centre de Valduc 21120 Is-Sur Tille (France)

    2008-07-01

    Towards disposal problematic, fine understanding of the {alpha} aging of UO{sub 2} and (U, Pu)O{sub 2} remains a fundamental challenge for the prediction of the potential increase of the radionuclide source terms with presence of water. The intrinsic evolution of the matrix is closely related to the behavior of radiogenic helium produced by actinide decay. Interactions between helium atoms and vacancy defects are involved in these mechanisms. Positron Annihilation Spectroscopy is also an appropriated method owing to its sensitivity to the vacancy type defects in solid materials. It is a non destructive technique with a remote acquiring data possibility. Because positron implanted in the material is sensitive to the electronic density, the positron lifetime method allows the characterization of the vacancy defects, namely size and concentration. Such equipment has been implemented in the L30 laboratory of the DHA facility in Atalante and will be applied on doped actinides samples, simulating {alpha} aging. This article presents, the analytical protocols and validation results on depleted UO{sub 2} samples and highlights the perspectives on (U, Pu)O{sub 2} for the investigation of different stages of self irradiation matrices and helium behavior. (authors)

  16. The effects of aging on compressive strength of low-level radioactive waste form samples

    International Nuclear Information System (INIS)

    McConnell, J.W. Jr.; Neilson, R.M. Jr.

    1996-06-01

    The Field Lysimeter Investigations: Low-Level Waste Data Base Development Program, funded by the US Nuclear Regulatory Commission (NRC), is (a) studying the degradation effects in organic ion-exchange resins caused by radiation, (b) examining the adequacy of test procedures recommended in the Branch Technical Position on Waste Form to meet the requirements of 10 CFR 61 using solidified ion-exchange resins, (c) obtaining performance information on solidified ion-exchange resins in a disposal environment, and (d) determining the condition of liners used to dispose ion-exchange resins. Compressive tests were performed periodically over a 12-year period as part of the Technical Position testing. Results of that compressive testing are presented and discussed. During the study, both portland type I-II cement and Dow vinyl ester-styrene waste form samples were tested. This testing was designed to examine the effects of aging caused by self-irradiation on the compressive strength of the waste forms. Also presented is a brief summary of the results of waste form characterization, which has been conducted in 1986, using tests recommended in the Technical Position on Waste Form. The aging test results are compared to the results of those earlier tests. 14 refs., 52 figs., 5 tabs

  17. A system for environmental monitoring

    International Nuclear Information System (INIS)

    Tawil, R.A.; Velbeck, K.J.; Rotunda, J.E.; Flory, C.; Moscovitch, M.

    1993-01-01

    The system described in this paper consists of a reader, multi-element dosemeters, and dose algorithm. The reader is a medium capacity non-contact gas heating unit interfaced to an application software package that evaluates and manages generated data. The dosemeter consists of elements that are 240 mg.cm -2 thick and which are symmetrically filtered. The two CaF 2 :Dy (TLD-200) elements are shielded by 80 mg.cm -2 ABS plastic, 0.25 mm tantalum and 0.05 mm lead. The two LiF:Mg,Ti (TLD-100) are shielded by the 80 mg.cm -2 ABS plastic only. The response of this system was characterised according to the criteria established in the ANSI Standard N545, Section 4, as modified by NRC Regulatory Guide 4.13. The procedures applied to study the energy response, fading, linearity, uniformity, minimum detectability, reproducibility, reponse dependence on angle of incidence are described, reviewed, and the results presented. The study also included self-irradiation, sensitivity to light and moisture, and performance in actual field conditions. The results demonstrate that this dosemeter satisfies all of the N545-1975 performance requirements. The dose calculation algorithm developed for this dosemeter is outlined and the accuracy of its performance in various pure and mixed fields has been determined. The results are presented and discussed. (author)

  18. Mechanical stability of a Cm-doped celsian glass-ceramic

    International Nuclear Information System (INIS)

    Routbort, J.L.; Offermann, P.; Matzke, H.

    1983-01-01

    Radiation damage due to a α-decay of actinides will modify the material used to store nuclear wastes. For example, ionization-induced processes can fragment the oxide bonds of a glass thereby creating gas bubbles. Phase decomposition, swelling, and disordering of crystalline phases are other possibilities. The self-irradiation damage could also affect the fracture properties of the storage materials. Spontaneous failure and fragmentation of some brittle materials have been observed during storage. The fracture toughness, K/sub Ic/, of a material is of technological and scientific interest. The ease with which a material can be handled and transported depends partially on K/sub Ic/. The resistance to fracture caused by unavoidable thermoelastic stresses is determined by K/sub Ic/. Cracking may, in the presence of water, lead to accelerated material degradation since the amount of leaching is proportional to the available surface area under non-stagnant conditions. This is especially important when the storage time is expected to be very long. From a scientific viewpoint, K/sub Ic/ is a fundamental parameter which characterizes the stress intensity factor at the onset of rapid crack growth resulting in failure. The Hertzian indentation technique was used to measure the fracture properties of a celsian glass-ceramic (B1-3) developed for high-level waste storage. Spontaneous failure due to radiation was not observed, on the contrary, the self-radiation damage caused by recoiling Pu atoms resulting from α-decay of a Cm-244 doped sample to a dose of congruent to 1.5 x 10 19 α-decays/cm 3 increases K/sub Ic/ by at least 25%. This increase in toughness is probably caused by the internal stresses which result from disordering due to the radiation damage. This is confirmed by the broadening of the x-ray spectra as the result of self-radiation

  19. Fabrication of uranium-americium mixed oxide fuels: thermodynamical modeling and materials properties

    International Nuclear Information System (INIS)

    Prieur, D.

    2011-01-01

    Fuel irradiation in pressurized water reactors lead to the formation of fission products and minor actinides (Np, Am, Cm) which can be transmuted in fast neutrons reactors. In this context, the aim of this work was to study the fabrication conditions of the U 1-y Am y O 2+x fuels which exhibit particular thermodynamical properties requiring an accurate monitoring of the oxygen potential during the sintering step. For this reason, a thermodynamical model was developed to assess the optimum sintering conditions for these materials. From these calculations, U 1-y Am y O 2+x (y=0.10; 0.15; 0.20; 0.30) were sintered in two range of atmosphere. In hyper-stoichiometric conditions at low temperature, porous and multiphasic compounds are obtained whereas in reducing conditions at high temperature materials are dense and monophasic. XAFS analyses were performed in order to obtain additional experimental data for the thermodynamical modeling refinement. These characterizations also showed the reduction of Am(+IV) to Am(+III) and the partial oxidation of U(+IV) to U(+V) due to a charge compensation mechanism occurring during the sintering. Finally, taking into account the high - activity of Am, self-irradiation effects were studied for two types of microstructures and two Am contents (10 and 15%). For each composition, a lattice parameter increase was observed without structural change coupled with a macroscopic swelling of the pellet diameter up to 1.2% for the dense compounds and 0.6% for the tailored porosity materials. (author) [fr

  20. Perspectives on the closed fuel cycle - Implications for high-level waste matrices

    International Nuclear Information System (INIS)

    Gras, Jean-Marie; Quang, Richard Do; Masson, Herve; Lieven, Thierry; Ferry, Cecile; Poinssot, Christophe; Debes, Michel; Delbecq, Jean-Michel

    2007-01-01

    Nuclear energy accounts for 80% of electricity production in France, generating approximately 1150 t of spent fuel for an electrical output of 420 TWh. Based on a reprocessing-conditioning-recycling strategy, the orientations taken by Electricite de France (EDF) for the mid-term and the far-future are to keep the fleet performances at the highest level, and to maintain the nuclear option fully open by the replacement of present pressurized water reactor (PWR) by new light water reactor (LWR), such as the evolutionary pressurized reactor (EPR) and future Generation IV designs. Adaptations of waste materials to new requirements will come with these orientations in order to meet long-term energy sustainability. In particular, waste materials and spent fuels are expected to meet increased requirements in comparison with the present situation. So the treatment of higher burn-up UO 2 spent fuel and MOX fuel requires determining the performances of glass and other matrices according to several criteria: chemical 'digestibility' (i.e. capacity of glass to incorporate fission products and minor actinides without loss of quality), resistance to alpha self-irradiation, residual power in view of disposal. Considering the long-term evolution of spent MOX fuel in storage, the helium production, the influence of irradiation damages accumulation and the evolution of the microstructure of the fuel pellet need to be known, as well as for the future fuels. Further, the eventual transmutation of minor actinides in fast neutron reactors (FR) of Generation IV, if its interest in optimising high-level waste management is proven, may also raise new challenges about the materials and fuel design. Some major questions in terms of waste materials and spent fuel are discussed in this paper

  1. Solid state synthesis and sintering of monazite-type ceramics: application to minor actinides conditioning

    International Nuclear Information System (INIS)

    Bregiroux, D.

    2005-11-01

    In the framework of the French law of 1991 concerning the nuclear waste management, several studies are undertaken to develop specific crystalline conditioning matrices. Monazite, a rare earth (TR 3+ ) orthophosphate with a general formula TR 3+ PO 4 , is a natural mineral containing significant amount of thorium and uranium. Monazite has been proposed as a host matrix for the minor actinides (Np, Am and Cm) specific conditioning, thanks to its high resistance to self irradiation and its low solubility. Its is now of prime importance to check the conservation of these properties on synthesized materials, which implies to master all the stages of the elaboration process, from the powder synthesis to the sintering of controlled microstructure pellets. This work can be divided into two main parts: The first part deals with the synthesis by high temperature solid state route of TR 3+ PO 4 powders (with TR 3+ = La 3+ to Gd 3+ , Pu 3+ and Am 3+ ). The chemical reactions occurring during the firing of starting reagents are described in the case of monazite with only one or several cations. From these results, a protocol of synthesis is described. The incorporation of tetravalent cations (Ce 4+ , U 4+ , Pu 4+ ) in the monazite structure was also studied. The second part of the present work deals with the elaboration of controlled density and microstructure monazite pellets and their related mechanical and thermal properties. The study of crushing and sintering is presented. For the first time, experimental results are confronted with theoretical models in order to deduce the densification and grain growth mechanisms. By the comprehension of the various physicochemical phenomena occurring during the various stages of the monazite pellets elaboration process (powder synthesis, crushing, sintering...), this work allowed the development of a protocol of elaboration of controlled microstructure monazite TR 3+ PO 4 pellets. The determination of some mechanical and thermal

  2. Modeling injected interstitial effects on void swelling in self-ion irradiation experiments

    Energy Technology Data Exchange (ETDEWEB)

    Short, M.P., E-mail: hereiam@mit.edu [Dept. of Nuclear Science and Engineering, Massachusetts Institute of Technology (United States); Gaston, D.R. [Idaho National Laboratory (United States); Jin, M. [Dept. of Nuclear Science and Engineering, Massachusetts Institute of Technology (United States); Shao, L. [Dept. of Nuclear Engineering, Texas A& M University (United States); Garner, F.A. [Radiation Effects Consulting, LLC (United States)

    2016-04-01

    Heavy ion irradiations at high dose rates are often used to simulate slow and expensive neutron irradiation experiments. However, many differences in the resultant modes of damage arise due to unique aspects of heavy ion irradiation. One such difference was recently shown in pure iron to manifest itself as a double peak in void swelling, with both peaks located away from the region of highest displacement damage. In other cases involving a variety of ferritic alloys there is often only a single peak in swelling vs. depth that is located very near the ion-incident surface. We show that these behaviors arise due to a combination of two separate effects: 1) suppression of void swelling due to injected interstitials, and 2) preferential sinking of interstitials to the ion-incident surface, which are very sensitive to the irradiation temperature and displacement rate. Care should therefore be used in collection and interpretation of data from the depth range outside the Bragg peak of ion irradiation experiments, as it is shown to be more complex than previously envisioned. - Highlights: • A model of the spatially dependent point defect kinetics equations with injected interstitials has been implemented. • The results predict a double peak in the void nucleation rate, helping to explain a recent experiment. • The double peak is predicted to be evident within a narrow (+/− 30 °C) temperature window for self-irradiation of pure iron. • The ballistic damage profile may not match the resultant void swelling profile from ion irradiation experiments.

  3. Study of the lattice parameter evolution of PWR irradiated MOX fuel by X-Ray diffraction; Etude de l'evolution du parametre cristallin des combustibles MOX irradies en rep par la methode de diffraction des rayons X

    Energy Technology Data Exchange (ETDEWEB)

    Clavier, B

    1995-07-01

    Fuel irradiation leads to a swelling resulting from the formation of gaseous (Kr, Xe) or solid fission products which are found either in solution or as solid inclusions in the matrix. This phenomena has to be evaluated to be taken into account in fuel cladding Interaction. Fuel swelling was studied as a function of burn up by measuring the corresponding cell constant evolution by X-Ray diffraction. This study was realized on Mixed Oxide Fuels (MOX) irradiated in a Pressurized Water Reactor (PWR) at different burn-up for 3 initial Pu contents. Lattice parameter evolutions were followed as a function of burn-up for the irradiated fuel with and without an annealing thermal treatment. These experimental evolutions are compared to the theoretical evolutions calculated from the hard sphere model, using the fission product concentrations determined by the APPOLO computer code. Contribution of varying parameters influencing the unit cell value is discussed. Thermal treatment effects were checked by metallography, X-Ray diffraction and microprobe analysis. After thermal treatment, no structural change was observed but a decrease of the lattice parameter was measured. This modification results essentially from self-irradiation defect annealing and not from stoichiometry variations. Microprobe analysis showed that about 15% of the formed Molybdenum is in solid solution In the oxide matrix. Micrographs showed the existence of Pu packs in the oxide matrix which induces a broadening of diffraction lines. The RIETVELD method used to analyze the X-Ray patterns did not allow to characterize independently the Pu packs and the oxide matrix lattice parameters. Nevertheless, with this method, the presence of micro-strains in the irradiated nuclear fuel could be confirmed. (author)

  4. Report on the scientific feasibility of new matrices for the conditioning of long lived radionuclides; Rapport sur la faisabilite scientifique des matrices nouvelles de conditionnement des radionucleides a vie longue

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-07-01

    New specific matrices for the conditioning of long lived radionuclides (I, Cs, Tc, minor actinides) have been developed. This report presents the conditions of their synthesis by sintering or melting and the quantifying of their crystallographic, physical and thermal properties. A 7% mass insertion of iodine can be reached with a phosphorus-vanadium-lead iodo-apatite. A 5% mass insertion of cesium is reached with the hollandite-type crystal structure (barium aluminate-titanate). An insertion level of at least 10% mass of rare earth oxides (simulating the presence of actinides) is reached for britholite, zirconolite, thorium phosphate, monazite, and zirconolite glass/ceramic materials. The chemical durability has been also determined. Enhanced aqueous corrosion resistance, 100 times better than for the glasses used today, are obtained for iodo-apatite (I), hollandite (Cs), britholite (actinides 3+/4+), thorium phosphate (actinides 4+) and monazite (3+/4+). The first elements of stability with respect to irradiation are reported for the minor actinide conditioning matrices. External post-irradiation examinations by heavy ion bombardment coupled to atomistic modeling have been performed. The characterization of self-irradiated natural analogues of britholite, zirconolite and monazite with more than 10{sup 20} {alpha}/g disintegrations confirms the very long time stability of these mineral structures (>10{sup 8} years). On the basis of the obtained results, it appears that the iodo-apatite, britholite, zirconolite, and thorium phosphate conditioning matrices have reached the stage of scientifical feasibility. The monazite matrice is on the way to reach the feasibility too. Other specific matrices for technetium (metal alloys) and cesium (hollandite) are also under development, but their long-term properties remain to be determined. (J.S.)

  5. Experimental demonstration of radiation effects on the performance of a stirling-alternator convertor and candidate materials evaluation

    Science.gov (United States)

    Mireles, Omar R.

    Free-piston Stirling power convertors are under consideration by NASA for service in the Advanced Stirling Radioisotope Generator (ASRG) and Fission Surface Power (FSP) systems to enable aggressive exploration missions by providing a reliable and constant power supply. The ASRG must withstand environmental radiation conditions, while the FSP system must tolerate a mixed neutron and gamma-ray environment resulting from self-irradiation. Stirling-alternators utilize rare earth magnets and a variety of organic materials whose radiation limits dominate service life estimates and shielding requirements. The project objective was to demonstrate the performance of the alternator, identify materials that exhibit excessive radiation sensitivity, identify radiation tolerant substitutes, establish empirical dose limits, and demonstrate the feasibility of cost effective nuclear and radiation tests by selection of the appropriate personnel and test facilities as a function of hardware maturity. The Stirling Alternator Radiation Test Article (SARTA) was constructed from linear alternator components of a Stirling convertor and underwent significant pre-exposure characterization. The SARTA was operated at the Sandia National Laboratories Gamma Irradiation Facility to a dose of over 40 Mrad. Operating performance was within nominal variation, although modestly decreasing trends occurred in later runs as well as the detection of an electrical fault after the final exposure. Post-irradiation disassembly and internal inspection revealed minimal degradation of the majority of the organic components. Radiation testing of organic material coupons was conducted since the majority of the literature was inconsistent. These inconsistencies can be attributed to testing at environmental conditions vastly different than those Stirling-alternator organics will experience during operation. Samples were irradiated at the Texas A&M TRIGA reactor to above expected FSP neutron fluence. A thorough

  6. Theoretical and practical implications of the effects of temperature during irradiation and during pre- and post-irradiation storage on the response of thermoluminescence dosimeters

    International Nuclear Information System (INIS)

    Gail de Planque, E.

    1984-01-01

    Experiments have been conducted to determine the applicability of the Randall-Wilkins theory for describing the behavior of CaF 2 :Mn thermoluminescence dosimeters (Harshaw TLD-400 chips). Results were obtained for four different conditions: irradiation followed by storage, irradiation after storage, irradiation both preceded and followed by storage, and continuous simultaneous irradiation and storage. The experiments were performed for storage intervals of approximately 1, 2, 3, 5, 6 and 7 days at five different storage temperatures: -25, +20, +65, +150 and +175 0 C. The results indicate fading that is described not by the Randall-Wilkins theory but rather as a linear function of the logarithm of the storage time. While the results suggest that the trapping efficiency is independent of temperature, they do demonstrate a small decrease in TL response with storage time prior to irradiation which is independent of temperature and time (>17 hours) and hence probably not dosimetric in origin but perhaps optically related. Glow curve analyses support the concept of a band of traps rather than a single trap. The overall results are compared to other data available in the literature most of which is for room-temperature storage. These data, for storage periods ranging from minutes to one year, can also be described as a linear function of the logarithm of the storage time and are remarkably consistent when uniformly normalized. Although peripheral experiments revealed problems associated with self-irradiation as well as a decline in sensitivity with use, the stability experiment results verify the highly favorable stability properties of CaF 2 :Mn for widespread application

  7. Electronic structure of Pu-Ce(-Ga) and Pu-Am(-Ga) alloys, stabilized in the {delta} phase; Structure electronique d'alliages Pu-Ce(-Ga) et Pu-Am(-Ga) stabilises en phase {delta}

    Energy Technology Data Exchange (ETDEWEB)

    Dormeval, M

    2001-09-01

    The behaviour of {delta}-plutonium, stable between 319 and 451 deg C, exhibits numerous singularities which are still a mystery for both physicists and metallurgists. This is due to its complex electronic structure, and in particular to the 5f electrons, which are at the edge between localization and delocalization. The stability domain of the {delta} phase can be extended down to room temperature by alloying with so called 'deltagen atoms' such as gallium (Ga), aluminum (A1), cerium (Ce) or americium (Am). The present work deals, one the one hand, with the influence of cerium and americium solutes regarding the localization of the 5f electrons of {delta}-plutonium, in binary Pu-Ce and Pu-Am alloys. On the other hand, the effect of two different deltagen solutes, simultaneously present, on the stability of the {delta} phase has been studied in ternary Pu-Am-Ga and Pu-Ce-Ga alloys. The electronic structure being strongly related to the crystalline organization, characterization methods such as X-Ray diffraction and EXAFS measurements were used together with electrical resistivity and magnetic susceptibility experiments. These showed that the roles of cerium and americium, supposed to be similar at the beginning of this investigation, are actually very different. Moreover, the additive effect of cerium and gallium, and, americium and gallium, has been demonstrated. Studying plutonium alloys, which are radioactive, also means following their evolution in time. The characteristics of the alloys have then been followed which allowed to detect, in Pu-Ce(-Ga) alloys, a destabilization of the {delta} phase and, to observe, in Pu-Am(-Ga) alloys, the influence of self-irradiation defects on the magnetic response. (author)

  8. An image-based skeletal dosimetry model for the ICRP reference newborn-internal electron sources

    International Nuclear Information System (INIS)

    Pafundi, Deanna; Lee, Choonsik; Bolch, Wesley; Rajon, Didier; Jokisch, Derek

    2010-01-01

    In this study, a comprehensive electron dosimetry model of newborn skeletal tissues is presented. The model is constructed using the University of Florida newborn hybrid phantom of Lee et al (2007 Phys. Med. Biol. 52 3309-33), the newborn skeletal tissue model of Pafundi et al (2009 Phys. Med. Biol. 54 4497-531) and the EGSnrc-based Paired Image Radiation Transport code of Shah et al (2005 J. Nucl. Med. 46 344-53). Target tissues include the active bone marrow (surrogate tissue for hematopoietic stem cells), shallow marrow (surrogate tissue for osteoprogenitor cells) and unossified cartilage (surrogate tissue for chondrocytes). Monoenergetic electron emissions are considered over the energy range 1 keV to 10 MeV for the following source tissues: active marrow, trabecular bone (surfaces and volumes), cortical bone (surfaces and volumes) and cartilage. Transport results are reported as specific absorbed fractions according to the MIRD schema and are given as skeletal-averaged values in the paper with bone-specific values reported in both tabular and graphic format as electronic annexes (supplementary data). The method utilized in this work uniquely includes (1) explicit accounting for the finite size and shape of newborn ossification centers (spongiosa regions), (2) explicit accounting for active and shallow marrow dose from electron emissions in cortical bone as well as sites of unossified cartilage, (3) proper accounting of the distribution of trabecular and cortical volumes and surfaces in the newborn skeleton when considering mineral bone sources and (4) explicit consideration of the marrow cellularity changes for active marrow self-irradiation as applicable to radionuclide therapy of diseased marrow in the newborn child.

  9. The Atalante facility at CEA/Marcoule: towards Gen IV systems fuel cycle

    Energy Technology Data Exchange (ETDEWEB)

    Bordier, Gilles; Warin, Dominique; Masson, Michel [CEA/Marcoule Direction, BP 17171 - 30207 - Bagnols-sur-Ceze Cedex (France)

    2008-07-01

    The Atalante facility is a complete set of 18 hot labs and 9 shielded cells devoted to the research and development on fuel cycle. The activities correspond to 4 major sectors of nuclear research: -) to support the operation of actual reprocessing plants with the aim of adapting the head of the process to the increase of the spend fuel burn-up and to different types of new burnt fuels to be reprocessed (including MOX, USi or UMo fuels); -) to develop the COEX{sup TM} process that jointly manages uranium and plutonium from the dissolution of spent fuel to the production of UPuO{sub 2} powder and the fabrication of MOX fuel pellets; -) to prepare the recycling of minor actinides (MA) by partitioning or by grouped actinide extraction, and by MA bearing fuel fabrication; -) to study the long term behavior of high level waste conditioning matrices and especially self irradiation and leaching of vitrified waste. The first hot lab of Atalante was operated in 1992, the process shielded cell (CBP) in 2003 and the last LN1 lab in 2005, while at the same time a large scale demonstration test on the DIAMEX-SANEX MA partitioning process was performed. Now some new challenges involve further necessary evolutions of the facility. Some are related to safety assessment and operating flexibility; the major evolutions will come from new scientific goals and research programs. Furthermore, minor actinides materials irradiation tests in fast reactors will be prepared in the framework of a large international cooperation (GACID program) and need the production of significant amounts of MA bearing mixed U-Pu oxide compounds in new hot labs and shielded cells equipment. The major new research tools are presented and we highlight how Atalante is a unique facility which brings a real opportunity to reinforce the European and international scientific cooperation in order to prepare the next Gen IV fuel cycle. (authors)

  10. A 3D Monte Carlo Method for Estimation of Patient-specific Internal Organs Absorbed Dose for 99mTc-hynic-Tyr3-octreotide Imaging

    International Nuclear Information System (INIS)

    Momennezhad, Mehdi; Nasseri, Shahrokh; Zakavi, Seyed Rasoul; Parach, Ali Asghar; Ghorbani, Mahdi; Asl, Ruhollah Ghahraman

    2016-01-01

    Single-photon emission computed tomography (SPECT)-based tracers are easily available and more widely used than positron emission tomography (PET)-based tracers, and SPECT imaging still remains the most prevalent nuclear medicine imaging modality worldwide. The aim of this study is to implement an image-based Monte Carlo method for patient-specific three-dimensional (3D) absorbed dose calculation in patients after injection of 99m Tc-hydrazinonicotinamide (hynic)-Tyr 3 -octreotide as a SPECT radiotracer. 99m Tc patient-speci@@@@@@c S values and the absorbed doses were calculated with GATE code for each source-target organ pair in four patients who were imaged for suspected neuroendocrine tumors. Each patient underwent multiple whole-body planar scans as well as SPECT imaging over a period of 1-24 h after intravenous injection of 99m hynic-Tyr 3 -octreotide. The patient-specific S values calculated by GATE Monte Carlo code and the corresponding S values obtained by MIRDOSE program differed within 4.3% on an average for self-irradiation, and differed within 69.6% on an average for cross-irradiation. However, the agreement between total organ doses calculated by GATE code and MIRDOSE program for all patients was reasonably well (percentage difference was about 4.6% on an average). Normal and tumor absorbed doses calculated with GATE were slightly higher than those calculated with MIRDOSE program. The average ratio of GATE absorbed doses to MIRDOSE was 1.07 ± 0.11 (ranging from 0.94 to 1.36). According to the results, it is proposed that when cross-organ irradiation is dominant, a comprehensive approach such as GATE Monte Carlo dosimetry be used since it provides more reliable dosimetric results

  11. Nondestructive Characterization of Aged Components

    Energy Technology Data Exchange (ETDEWEB)

    Panetta, Paul D.; Toloczko, Mychailo B.; Garner, Francis A.; Balachov, Iouri I.

    2003-10-21

    It is known that high energy radiation can have numerous effects on materials. In metals and alloys, the effects include, but may not be limited to, mechanical property changes, physical property changes, compositional changes, phase changes, and dimensional changes. Metals and alloys which undergo high energy self-irradiation are also susceptible to these changes. One of the greatest concerns with irradiation of materials is the phenomenon of void swelling which has been observed in a wide variety of metals and alloys. Irradiation causes the formation of a high concentration point defects and microclusters of vacancies and interstitials. With the assistance of an inert atom such as helium, the vacancy-type defects can coalesce to form a stable bubble. This bubble will continue to grow through the net absorption of more vacancy-type defects and helium atoms, and upon reaching a certain critical size, the bubble will begin to grow at an accelerated rate without the assistance of inert atom absorption. The bubble is then said to be an unstably growing void. Depending on the alloy system and environment, swelling values can reach in excess of 50% !V/Vo where Vo is the initial volume of the material. Along with dimensional changes resulting from the formation of bubbles and voids comes changes in the macroscopically observed speed of sound, moduli, electrical resistivity, yield strength, and other properties. These effects can be detrimental to the designed operation of the aged components. In situations where irradiation has sufficient time to cause degradation to materials used in critical applications such as nuclear reactor core structural materials, it is advisable to regularly survey the material properties. It is common practice to use surveillance specimens, but this is not always possible. When surveillance materials are not available, other means for surveying the material properties must be utilized. Sometimes it is possible to core out a small sample which

  12. The Atalante facility at CEA/Marcoule: towards Gen IV systems fuel cycle

    International Nuclear Information System (INIS)

    Bordier, Gilles; Warin, Dominique; Masson, Michel

    2008-01-01

    The Atalante facility is a complete set of 18 hot labs and 9 shielded cells devoted to the research and development on fuel cycle. The activities correspond to 4 major sectors of nuclear research: -) to support the operation of actual reprocessing plants with the aim of adapting the head of the process to the increase of the spend fuel burn-up and to different types of new burnt fuels to be reprocessed (including MOX, USi or UMo fuels); -) to develop the COEX TM process that jointly manages uranium and plutonium from the dissolution of spent fuel to the production of UPuO 2 powder and the fabrication of MOX fuel pellets; -) to prepare the recycling of minor actinides (MA) by partitioning or by grouped actinide extraction, and by MA bearing fuel fabrication; -) to study the long term behavior of high level waste conditioning matrices and especially self irradiation and leaching of vitrified waste. The first hot lab of Atalante was operated in 1992, the process shielded cell (CBP) in 2003 and the last LN1 lab in 2005, while at the same time a large scale demonstration test on the DIAMEX-SANEX MA partitioning process was performed. Now some new challenges involve further necessary evolutions of the facility. Some are related to safety assessment and operating flexibility; the major evolutions will come from new scientific goals and research programs. Furthermore, minor actinides materials irradiation tests in fast reactors will be prepared in the framework of a large international cooperation (GACID program) and need the production of significant amounts of MA bearing mixed U-Pu oxide compounds in new hot labs and shielded cells equipment. The major new research tools are presented and we highlight how Atalante is a unique facility which brings a real opportunity to reinforce the European and international scientific cooperation in order to prepare the next Gen IV fuel cycle. (authors)

  13. Response functions for computing absorbed dose to skeletal tissues from photon irradiation-an update

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Perry B; Bahadori, Amir A [Nuclear and Radiological Engineering, University of Florida, Gainesville, FL 32611 (United States); Eckerman, Keith F [Life Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Lee, Choonsik [Radiation Epidemiology Branch, National Cancer Institute, Bethesda, MD 20892 (United States); Bolch, Wesley E, E-mail: wbolch@ufl.edu [Nuclear and Radiological/Biomedical Engineering, University of Florida, Gainesville, FL 32611 (United States)

    2011-04-21

    A comprehensive set of photon fluence-to-dose response functions (DRFs) is presented for two radiosensitive skeletal tissues-active and total shallow marrow-within 15 and 32 bone sites, respectively, of the ICRP reference adult male. The functions were developed using fractional skeletal masses and associated electron-absorbed fractions as reported for the UF hybrid adult male phantom, which in turn is based upon micro-CT images of trabecular spongiosa taken from a 40 year male cadaver. The new DRFs expand upon both the original set of seven functions produced in 1985, and a 2007 update calculated under the assumption of secondary electron escape from spongiosa. In this study, it is assumed that photon irradiation of the skeleton will yield charged particle equilibrium across all spongiosa regions at energies exceeding 200 keV. Kerma coefficients for active marrow, inactive marrow, trabecular bone and spongiosa at higher energies are calculated using the DRF algorithm setting the electron-absorbed fraction for self-irradiation to unity. By comparing kerma coefficients and DRF functions, dose enhancement factors and mass energy-absorption coefficient (MEAC) ratios for active marrow to spongiosa were derived. These MEAC ratios compared well with those provided by the NIST Physical Reference Data Library (mean difference of 0.8%), and the dose enhancement factors for active marrow compared favorably with values calculated in the well-known study published by King and Spiers (1985 Br. J. Radiol. 58 345-56) (mean absolute difference of 1.9 percentage points). Additionally, dose enhancement factors for active marrow were shown to correlate well with the shallow marrow volume fraction (R{sup 2} = 0.91). Dose enhancement factors for the total shallow marrow were also calculated for 32 bone sites representing the first such derivation for this target tissue.

  14. Mono and sequential ion irradiation induced damage formation and damage recovery in oxide glasses: Stopping power dependence of the mechanical properties

    International Nuclear Information System (INIS)

    Mir, A.H.; Monnet, I.; Toulemonde, M.; Bouffard, S.; Jegou, C.; Peuget, S.

    2016-01-01

    Simple and complex borosilicate glasses were irradiated with single and double ion beams of light and heavy ions over a broad fluence and stopping power range. As a result of the heavy ion irradiation (U, Kr, Au), the hardness was observed to diminish and saturate after a decrease by 35 ± 1%. Unlike slow and swift heavy ion irradiation, irradiation with light ions (He,O) induced a saturation hardness decrease of 18 ± 1% only. During double ion beam irradiation; where glasses were first irradiated with a heavy ion (gold) and then by a light ion (helium), the light ion irradiation induced partial damage recovery. As a consequence of the recovery effect, the hardness of the pre-irradiated glasses increased by 10–15% depending on the chemical composition. These results highlight that the nuclear energy loss and high electronic energy loss (≥4 keV/nm) result in significant and similar modifications whereas light ions with low electronic energy loss (≤1 keV/nm) result in only mild damage formation in virgin glasses and recovery in highly pre-damaged glasses. These results are important to understand the damage formation and recovery in actinide bearing minerals and in glasses subjected to self-irradiation by alpha decays. - Highlights: • Behavior of glasses strongly depends on the electronic energy loss (Se) of the ions. • High Se (≥4 keV/nm) induces large changes in comparison to lower Se values. • Apart from mild damage formation, low Se causes recovery of pre-existing damage. • Alpha induced partial recovery of the damage would occur in nuclear waste glasses.

  15. Study of the lattice parameter evolution of PWR irradiated MOX fuel by X-Ray diffraction

    International Nuclear Information System (INIS)

    Clavier, B.

    1995-01-01

    Fuel irradiation leads to a swelling resulting from the formation of gaseous (Kr, Xe) or solid fission products which are found either in solution or as solid inclusions in the matrix. This phenomena has to be evaluated to be taken into account in fuel cladding Interaction. Fuel swelling was studied as a function of burn up by measuring the corresponding cell constant evolution by X-Ray diffraction. This study was realized on Mixed Oxide Fuels (MOX) irradiated in a Pressurized Water Reactor (PWR) at different burn-up for 3 initial Pu contents. Lattice parameter evolutions were followed as a function of burn-up for the irradiated fuel with and without an annealing thermal treatment. These experimental evolutions are compared to the theoretical evolutions calculated from the hard sphere model, using the fission product concentrations determined by the APPOLO computer code. Contribution of varying parameters influencing the unit cell value is discussed. Thermal treatment effects were checked by metallography, X-Ray diffraction and microprobe analysis. After thermal treatment, no structural change was observed but a decrease of the lattice parameter was measured. This modification results essentially from self-irradiation defect annealing and not from stoichiometry variations. Microprobe analysis showed that about 15% of the formed Molybdenum is in solid solution In the oxide matrix. Micrographs showed the existence of Pu packs in the oxide matrix which induces a broadening of diffraction lines. The RIETVELD method used to analyze the X-Ray patterns did not allow to characterize independently the Pu packs and the oxide matrix lattice parameters. Nevertheless, with this method, the presence of micro-strains in the irradiated nuclear fuel could be confirmed. (author)

  16. Lethal Effect on Bacterium of Decay of Incorporated Radioactive Atoms (3H, 14C, 32P)

    International Nuclear Information System (INIS)

    Apelgot, Sonia

    1968-01-01

    The biological effect of decay of 3 H, 14 C and 32 P incorporated into a bacterium depends on the nature of the organic molecule labelled, on the position of the isotope within it and on the isotope itself. In sum, results obtained to date show that: The decay of 3 H atoms incorporated into certain macromolecules of a bacterium causes sterilization through ionization by the ß - particle emitted; transmutation is of negligible importance. This self-irradiation is comparable in effect with X-rays and is affected in a similar manner by the same factors: temperature, presence of a radioprotector, radiosensitivity of the strain. Decay of 14 C or 32 P atoms incorporated into bacterial DNA is lethal because of the transmutation effect; ionizations produced by emitted ß - particles may be disregarded. Survival curves for 32 P transmutations depend on the experimental conditions. Some of the results obtained with 32 P are similar to those obtained with X-rays, e.g. effects of temperature, radical capture and oxygen, while others are similar to those of u.v. light, e.g., effect of growth conditions. Comparative tests made with 32 P indicate that the recoil energy of transmutation is not the phenomenon responsible for the lethal effect observed. Comparison of the results obtained after X-irradiation or decay of 3 H or 32 P incorporated into the DNA of bacteria of the same strain of E. coli shows that the efficiency of a 32 P transmutation is about four times greater than that of an ionization produced at random within the same DNA. (author) [fr

  17. Electronic structure of Pu-Ce(-Ga) and Pu-Am(-Ga) alloys, stabilized in the {delta} phase; Structure electronique d'alliages Pu-Ce(-Ga) et Pu-Am(-Ga) stabilises en phase {delta}

    Energy Technology Data Exchange (ETDEWEB)

    Dormeval, M

    2001-09-01

    The behaviour of {delta}-plutonium, stable between 319 and 451 deg C, exhibits numerous singularities which are still a mystery for both physicists and metallurgists. This is due to its complex electronic structure, and in particular to the 5f electrons, which are at the edge between localization and delocalization. The stability domain of the {delta} phase can be extended down to room temperature by alloying with so called 'deltagen atoms' such as gallium (Ga), aluminum (A1), cerium (Ce) or americium (Am). The present work deals, one the one hand, with the influence of cerium and americium solutes regarding the localization of the 5f electrons of {delta}-plutonium, in binary Pu-Ce and Pu-Am alloys. On the other hand, the effect of two different deltagen solutes, simultaneously present, on the stability of the {delta} phase has been studied in ternary Pu-Am-Ga and Pu-Ce-Ga alloys. The electronic structure being strongly related to the crystalline organization, characterization methods such as X-Ray diffraction and EXAFS measurements were used together with electrical resistivity and magnetic susceptibility experiments. These showed that the roles of cerium and americium, supposed to be similar at the beginning of this investigation, are actually very different. Moreover, the additive effect of cerium and gallium, and, americium and gallium, has been demonstrated. Studying plutonium alloys, which are radioactive, also means following their evolution in time. The characteristics of the alloys have then been followed which allowed to detect, in Pu-Ce(-Ga) alloys, a destabilization of the {delta} phase and, to observe, in Pu-Am(-Ga) alloys, the influence of self-irradiation defects on the magnetic response. (author)

  18. Report on the scientific feasibility of new matrices for the conditioning of long lived radionuclides

    International Nuclear Information System (INIS)

    2001-01-01

    New specific matrices for the conditioning of long lived radionuclides (I, Cs, Tc, minor actinides) have been developed. This report presents the conditions of their synthesis by sintering or melting and the quantifying of their crystallographic, physical and thermal properties. A 7% mass insertion of iodine can be reached with a phosphorus-vanadium-lead iodo-apatite. A 5% mass insertion of cesium is reached with the hollandite-type crystal structure (barium aluminate-titanate). An insertion level of at least 10% mass of rare earth oxides (simulating the presence of actinides) is reached for britholite, zirconolite, thorium phosphate, monazite, and zirconolite glass/ceramic materials. The chemical durability has been also determined. Enhanced aqueous corrosion resistance, 100 times better than for the glasses used today, are obtained for iodo-apatite (I), hollandite (Cs), britholite (actinides 3+/4+), thorium phosphate (actinides 4+) and monazite (3+/4+). The first elements of stability with respect to irradiation are reported for the minor actinide conditioning matrices. External post-irradiation examinations by heavy ion bombardment coupled to atomistic modeling have been performed. The characterization of self-irradiated natural analogues of britholite, zirconolite and monazite with more than 10 20 α/g disintegrations confirms the very long time stability of these mineral structures (>10 8 years). On the basis of the obtained results, it appears that the iodo-apatite, britholite, zirconolite, and thorium phosphate conditioning matrices have reached the stage of scientifical feasibility. The monazite matrice is on the way to reach the feasibility too. Other specific matrices for technetium (metal alloys) and cesium (hollandite) are also under development, but their long-term properties remain to be determined. (J.S.)

  19. An image-based skeletal dosimetry model for the ICRP reference newborn-internal electron sources

    Energy Technology Data Exchange (ETDEWEB)

    Pafundi, Deanna; Lee, Choonsik; Bolch, Wesley [Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, FL (United States); Rajon, Didier [Department of Neurosurgery, University of Florida, Gainesville, FL (United States); Jokisch, Derek [Department of Physics and Astronomy, Francis Marion University, Florence, SC (United States)], E-mail: wbolch@ufl.edu

    2010-04-07

    In this study, a comprehensive electron dosimetry model of newborn skeletal tissues is presented. The model is constructed using the University of Florida newborn hybrid phantom of Lee et al (2007 Phys. Med. Biol. 52 3309-33), the newborn skeletal tissue model of Pafundi et al (2009 Phys. Med. Biol. 54 4497-531) and the EGSnrc-based Paired Image Radiation Transport code of Shah et al (2005 J. Nucl. Med. 46 344-53). Target tissues include the active bone marrow (surrogate tissue for hematopoietic stem cells), shallow marrow (surrogate tissue for osteoprogenitor cells) and unossified cartilage (surrogate tissue for chondrocytes). Monoenergetic electron emissions are considered over the energy range 1 keV to 10 MeV for the following source tissues: active marrow, trabecular bone (surfaces and volumes), cortical bone (surfaces and volumes) and cartilage. Transport results are reported as specific absorbed fractions according to the MIRD schema and are given as skeletal-averaged values in the paper with bone-specific values reported in both tabular and graphic format as electronic annexes (supplementary data). The method utilized in this work uniquely includes (1) explicit accounting for the finite size and shape of newborn ossification centers (spongiosa regions), (2) explicit accounting for active and shallow marrow dose from electron emissions in cortical bone as well as sites of unossified cartilage, (3) proper accounting of the distribution of trabecular and cortical volumes and surfaces in the newborn skeleton when considering mineral bone sources and (4) explicit consideration of the marrow cellularity changes for active marrow self-irradiation as applicable to radionuclide therapy of diseased marrow in the newborn child.

  20. DNA damage in blood lymphocytes in patients after {sup 177}Lu peptide receptor radionuclide therapy

    Energy Technology Data Exchange (ETDEWEB)

    Eberlein, Uta; Bluemel, Christina; Buck, Andreas Konrad; Werner, Rudolf Alexander; Lassmann, Michael [University of Wuerzburg, Department of Nuclear Medicine, Wuerzburg (Germany); Nowak, Carina; Scherthan, Harry [Bundeswehr Institute of Radiobiology affiliated to the University of Ulm, Munich (Germany)

    2015-10-15

    The aim of the study was to investigate DNA double strand break (DSB) formation and its correlation with the absorbed dose to the blood lymphocytes of patients undergoing their first peptide receptor radionuclide therapy (PRRT) with {sup 177}Lu-labelled DOTATATE/DOTATOC. The study group comprised 16 patients receiving their first PRRT. At least six peripheral blood samples were obtained before, and between 0.5 h and 48 h after radionuclide administration. From the time-activity curves of the blood and the whole body, residence times for blood self-irradiation and whole-body irradiation were determined. Peripheral blood lymphocytes were isolated, fixed with ethanol and subjected to immunofluorescence staining for colocalizing γ-H2AX/53BP1 DSB-marking foci. The average number of DSB foci per cell per patient sample was determined as a function of the absorbed dose to the blood and compared with an in vitro calibration curve established in our laboratory with {sup 131}I and {sup 177}Lu. The average number of radiation-induced foci (RIF) per cell increased over the first 5 h after radionuclide administration and decreased thereafter. A linear fit from 0 to 5 h as a function of the absorbed dose to the blood agreed with our in vitro calibration curve. At later time-points the number of RIF decreased, indicating progression of DNA repair. Measurements of RIF and the absorbed dose to the blood after systemic administration of {sup 177}Lu may be used to obtain data on the individual dose-response relationships in vivo. Individual patient data were characterized by a linear dose-dependent increase and an exponential decay function describing repair. (orig.)

  1. Investigation of plutonium-239 conditioning in monazite and brabantite matrices: Synthesis and characterization

    International Nuclear Information System (INIS)

    Glorieux, B.; Jorion, F.; Montel, J.M.; Matecki, M.; Deschanels, X.; Coutures, JP.

    2004-01-01

    In response to the 1991 French radioactive waste management act, a research program was set up between the CNRS, the CEA and French universities to propose effective minor actinide disposal matrices capable of loading 10 wt% of actinide oxides and ensuring a hundred-fold better leaching performance than 'R7T7' glass. The lanthanide ortho-phosphates LaPO 4 could constitute an excellent matrix for this purpose. In this type of structure, the (PO 4 ) 3- negative entity is compensated by trivalent cations such as La, Ce, Gd, Pu, Am (monazite) or equal fractions of divalent and tetravalent cations such as Ca 2+ Th 4+ , Ca 2+ U 4+ , Ca 2+ Np 4+ (brabantite). Previous leach tests and geological discoveries have shown that these materials are highly resistant to leaching and conserve their crystalline state even in aqueous media. These points led us to investigate the incorporation of 10 wt% PuO 2 in monazite and brabantite materials and to study the effects of self-irradiation on their structural states. Prior to plutonium conditioning tests, experiments were performed in the laboratory using cerium and thorium oxides according to the following reactions: (1-3x)LaPO 4 + 2xCe 4+ O 2 + xLa(PO 3 ) 3 → La 1-2x Ce 2x 3+ PO 4 + x/2O 2 ; (1-3x)LaPO 4 + xTh 4+ O 2 + xCaO + xLa(PO 3 ) 3 → La 1-2x Ca x Th x 4+ PO 4 . Cerium oxide was used to study the reduction of a tetravalent cation to a trivalent state in a phosphate structure and to prepare for Pu 3+ conditioning. Thorium was used to study the conditioning of tetravalent cations such as Pu 4+ . The parameters and sintering reaction of the final product were optimized. In a radioactive laboratory, PuO 2 was then substituted for CeO 2 and ThO 2 in the first and second reactions mentioned above, respectively. The synthesis and sintering procedures were unchanged. X-ray diffraction analysis of the powder before and after sintering showed promising results that are discussed. (authors)

  2. Investigation of plutonium-239 conditioning in monazite and brabantite matrices: Synthesis and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Glorieux, B.; Jorion, F.; Montel, J.M.; Matecki, M.; Deschanels, X.; Coutures, JP

    2004-07-01

    In response to the 1991 French radioactive waste management act, a research program was set up between the CNRS, the CEA and French universities to propose effective minor actinide disposal matrices capable of loading 10 wt% of actinide oxides and ensuring a hundred-fold better leaching performance than 'R7T7' glass. The lanthanide ortho-phosphates LaPO{sub 4} could constitute an excellent matrix for this purpose. In this type of structure, the (PO{sub 4}){sup 3-} negative entity is compensated by trivalent cations such as La, Ce, Gd, Pu, Am (monazite) or equal fractions of divalent and tetravalent cations such as Ca{sup 2+}Th{sup 4+}, Ca{sup 2+}U{sup 4+}, Ca{sup 2+}Np{sup 4+} (brabantite). Previous leach tests and geological discoveries have shown that these materials are highly resistant to leaching and conserve their crystalline state even in aqueous media. These points led us to investigate the incorporation of 10 wt% PuO{sub 2} in monazite and brabantite materials and to study the effects of self-irradiation on their structural states. Prior to plutonium conditioning tests, experiments were performed in the laboratory using cerium and thorium oxides according to the following reactions: (1-3x)LaPO{sub 4} + 2xCe{sup 4+}O{sub 2} + xLa(PO{sub 3}){sub 3} {yields} La{sub 1-2x}Ce{sub 2x}{sup 3+}PO{sub 4} + x/2O{sub 2}; (1-3x)LaPO{sub 4} + xTh{sup 4+}O{sub 2} + xCaO + xLa(PO{sub 3}){sub 3} {yields} La{sub 1-2x}Ca{sub x}Th{sub x}{sup 4+}PO{sub 4}. Cerium oxide was used to study the reduction of a tetravalent cation to a trivalent state in a phosphate structure and to prepare for Pu{sup 3+} conditioning. Thorium was used to study the conditioning of tetravalent cations such as Pu{sup 4+}. The parameters and sintering reaction of the final product were optimized. In a radioactive laboratory, PuO{sub 2} was then substituted for CeO{sub 2} and ThO{sub 2} in the first and second reactions mentioned above, respectively. The synthesis and sintering procedures were

  3. Solid state synthesis and sintering of monazite-type ceramics: application to minor actinides conditioning; Synthese par voie solide et frittage de ceramiques a structure monazite. Application au conditionnement des actinides mineurs

    Energy Technology Data Exchange (ETDEWEB)

    Bregiroux, D

    2005-11-15

    In the framework of the French law of 1991 concerning the nuclear waste management, several studies are undertaken to develop specific crystalline conditioning matrices. Monazite, a rare earth (TR{sup 3+}) orthophosphate with a general formula TR{sup 3+}PO{sub 4}, is a natural mineral containing significant amount of thorium and uranium. Monazite has been proposed as a host matrix for the minor actinides (Np, Am and Cm) specific conditioning, thanks to its high resistance to self irradiation and its low solubility. Its is now of prime importance to check the conservation of these properties on synthesized materials, which implies to master all the stages of the elaboration process, from the powder synthesis to the sintering of controlled microstructure pellets. This work can be divided into two main parts: The first part deals with the synthesis by high temperature solid state route of TR{sup 3+}PO{sub 4} powders (with TR{sup 3+} = La{sup 3+} to Gd{sup 3+}, Pu{sup 3+} and Am{sup 3+}). The chemical reactions occurring during the firing of starting reagents are described in the case of monazite with only one or several cations. From these results, a protocol of synthesis is described. The incorporation of tetravalent cations (Ce{sup 4+}, U{sup 4+}, Pu{sup 4+}) in the monazite structure was also studied. The second part of the present work deals with the elaboration of controlled density and microstructure monazite pellets and their related mechanical and thermal properties. The study of crushing and sintering is presented. For the first time, experimental results are confronted with theoretical models in order to deduce the densification and grain growth mechanisms. By the comprehension of the various physicochemical phenomena occurring during the various stages of the monazite pellets elaboration process (powder synthesis, crushing, sintering...), this work allowed the development of a protocol of elaboration of controlled microstructure monazite TR{sup 3+}PO{sub 4

  4. Cascade statistics in the binary collision approximation and in full molecular dynamics

    International Nuclear Information System (INIS)

    Hou, M.; Pan, Z.Y.

    1995-01-01

    The Binary Collision Approximation (BCA) and Molecular Dynamics (MD) are used to simulate low energy atomic collision cascades in solids. Results are compared and discussed on the example of copper and gold self irradiation. For MD, long range N-body potentials are built, similar to those deduced from the second moment semi-empirical tight binding model. The pair interaction contribution is splined to a Moliere screened Coulomb potential at small separation distances. The BCA calculations are performed with the MARLOWE program, using the same Moliere potential as for MD, and modelling the N-body contribution by a binding of the atoms to their equilibrium lattice sites. The scattering integrals are estimated by means of a 4 points Gauss-Mehler quadrature. In MD, the NVT equations of motion are integrated with a constant time step of 2 fs. For the NVE cascade simulations, the Newton equations of motion are solved with a dynamically adjusted time step, kept lower than 2 fs. The influence of the time step on the simulated trajectories is discussed. The mean number of moving atoms with total energy above threshold values ranging from 1 to 100 eV is estimated as a function of time over 300 fs both with MARLOWE and by MD. This estimate is repeated for external primary energies ranging from 250 eV to 1 keV. In the case of copper, the BCA results are found to be in remarkable agreement with MD over about 200 fs cascade development, provided the size of the crystallite used in MD is sufficiently large in order to account for the early mechanical response of the close environment. This agreement between the two methods is found to be the best when the binding energy of the target atoms as modelled in the BCA is adjusted to a value close to the cohesive energy. In the case of gold, the agreement between BCA and MD is reasonable and the results suggest the need of an accurate modelling of linear collision sequences in the BCA. (orig.)

  5. Structure, thermal stability and resistance under external irradiation of rare earths and molybdenum-rich alumino-borosilicate glasses

    International Nuclear Information System (INIS)

    Chouard, N.

    2011-01-01

    In France, the highly radioactive nuclear liquid wastes arising from spent nuclear fuel reprocessing (fission products + minor actinides (FPA)) are currently immobilized in an alumino-borosilicate glass called 'R7T7'. In the future, the opportunity of using new alumino-borosilicate glass compositions (HTC glasses) is considered in order to increase the waste loading in glasses and thus significantly decrease the number of glass canisters. However, the increase of the concentration of FPA could lead to the crystallization of rare-earth-rich phases (Ca 2 RE 8 (SiO 4 ) 6 O 2 ) or molybdenum-rich phases (CaMoO 4 , Na 2 MoO 4 ) during melt cooling, which can modify the confinement properties of the glass (chemical durability, self-irradiation resistance..), particularly if they can incorporate radionuclides α or β in their structure. This thesis can be divided into two parts: The first part deals with studying the relationship that can occur between the composition, the structure and the crystallization tendency of simplified seven oxides glasses, belonging to the SiO 2 -B 2 O 3 -Al 2 O 3 -Na 2 O-CaO-MoO 3 -Nd 2 O 3 system and derived from the composition of the HTC glass at 22,5 wt. % in FPA. The impact of the presence of platinoid elements (RuO 2 in our case) on the crystallization of the different phases is also studied. The second part deals with the effect of actinides α decays and more particularly of nuclear interactions essentially coming from recoil nuclei (simulated here by heavy ions external irradiations) on the behaviour under irradiation of an alumino-borosilicate glass containing apatite Ca 2 Nd 8 (SiO 4 ) 6 O 2 crystals, that can incorporate actinides in their structure. Two samples containing apatite crystals with different size are studied, in order to understand the impact of microstructure on the irradiation resistance of this kind of material. (author) [fr

  6. Inhibition of the radiolytic hydrogen production in the nuclear waste of 'bitumen coated' type: study of the interaction between hydrogen and cobalt hydroxo-sulphide

    International Nuclear Information System (INIS)

    Pichon, C.

    2006-11-01

    In the nuclear field in France, the bitumen is mainly used for the conditioning of the radioactive muds generated by the fuel reprocessing. However, the self-irradiation of the bitumen induces a production of hydrogen which generates safety problems. The comparison of various storage sites showed that the presence of cobalt hydroxo sulphide limited such a production. Consequently, this compound was regarded as an 'inhibitor of radiolytic hydrogen production'. However, the origin of this phenomenon was not clearly identified. In order to propose an explanation to this inhibition phenomenon, model organic molecules were used to represent the components of the bitumen. Irradiations were carried out by protons to simulate the alpha radiolysis. The organic molecules irradiations by a proton beam showed that cobalt hydroxo sulphide CoSOH, does not act as a hydrogenation catalyst of unsaturated hydrocarbons, nor as a radicals scavenger, but consists of a trap of hydrogen. Experiments of hydrogen trapping at ambient temperature were carried out according to two techniques: gravimetry and manometry. The solid was characterized before and after interaction with hydrogen (infrared and Raman spectroscopies, X-ray diffraction). The initial solid was composed of amorphous cobalt hydroxo sulphide and a minor phase of cobalt hydroxide. The gravimetry and manometry experiments showed that the maximum of hydrogen trapping capacity is equal to 0.59 ± 0.18 mole of hydrogen per mole of cobalt. After interaction with hydrogen, the Co(OH) 2 phase disappeared and a new solid phase appeared corresponding to Co 9 S 8 . These observations, as well as the analysis of the gas phase, made it possible to conclude with the following reaction (1): 9 CoSOH + 11/2 H 2 = Co 9 S 8 + 9 H 2 O + H 2 S (1). Gravimetry experiments at temperatures between 50 and 210 C revealed the desorption of water but not of hydrogen sulphide. The absence of hydrogen sulphide in gaseous phase and the Co(OH) 2 phase

  7. Considerations of anthropometric, tissue volume, and tissue mass scaling for improved patient specificity of skeletal S values

    International Nuclear Information System (INIS)

    Bolch, W.E.; Patton, P.W.; Shah, A.P.; Rajon, D.A.; Jokisch, D.W.

    2002-01-01

    It is generally acknowledged that reference man (70 kg in mass and 170 cm in height) does not adequately represent the stature and physical dimensions of many patients undergoing radionuclide therapy, and thus scaling of radionuclide S values is required for patient specificity. For electron and beta sources uniformly distributed within internal organs, the mean dose from self-irradiation is noted to scale inversely with organ mass, provided no escape of electron energy occurs at the organ boundaries. In the skeleton, this same scaling approach is further assumed to be correct for marrow dosimetry; nevertheless, difficulties in quantitative assessments of marrow mass in specific skeletal regions of the patient make this approach difficult to implement clinically. Instead, scaling of marrow dose is achieved using various anthropometric parameters that presumably scale in the same proportion. In this study, recently developed three-dimensional macrostructural transport models of the femoral head and humeral epiphysis in three individuals (51-year male, 82-year female, and 86-year female) are used to test the abilities of different anthropometric parameters (total body mass, body surface area, etc.) to properly scale radionuclide S values from reference man models. The radionuclides considered are 33 P, 177 Lu, 153 Sm, 186 Re, 89 Sr, 166 Ho, 32 P, 188 Re, and 90 Y localized in either the active marrow or endosteal tissues of the bone trabeculae. S value scaling is additionally conducted in which the 51-year male subject is assigned as the reference individual; scaling parameters are then expanded to include tissue volumes and masses for both active marrow and skeletal spongiosa. The study concludes that, while no single anthropometric parameter emerges as a consistent scaler of reference man S values, lean body mass is indicated as an optimal scaler when the reference S values are based on 3D transport techniques. Furthermore, very exact patient-specific scaling of

  8. Radiation effects on oxide glasses: Importance of energy deposition and relaxation processes

    International Nuclear Information System (INIS)

    Mir, Anamul-Haq

    2015-01-01

    Nuclear waste glass matrices during their disposal will be subjected to self-irradiation by beta and alpha decays. Beta emitting radionuclides due to their short half life time will be the dominant radiation source only during first few hundred years of the disposal, whereas the alpha decays constitute a long term radiation source. Due to intense beta decay and associated gamma rays, the glass matrices can attain temperatures up to 300 C during state 1. The temperature during stage 2 will mainly be defined by the repository conditions. The present work focused on studying the response of various glasses (borosilicate glasses of nuclear waste interest and amorphous silica) to electron irradiation (to understand the response of the pristine glasses to beta decays), single ion beam irradiations with light and heavy ions over a wide stopping power and fluence range (to study the response of the pristine glasses as a function of the electronic and nuclear energy loss so as to establish the necessary conditions for simulating the alpha and recoil nuclei damage), sequential electron-ion irradiations (to understand the impact of the intense beta decay damage during stage 1 on subsequent alpha decay during stage 2, and double ion beam sequential and simultaneous irradiations (to understand the interaction of the alpha particles with recoil nuclei pre-damaged glass and vice versa). The pristine and irradiated samples were characterized using Raman spectroscopy, NMR spectroscopy, micro and nano indentation, AFM, interferometry and ToF-SIMS. Apart from the experimental work, Inelastic Thermal Spike Model (iTSM) for ion track formation was extended to borosilicate glasses to study the possibility of ion track formation in nuclear waste glass matrices. The model was used to study the impact of matrix temperature and stored energy on the ion track threshold, which is otherwise difficult to study experimentally. During electron irradiation, the response of the glasses was found to

  9. Spent fuel workshop'2002

    International Nuclear Information System (INIS)

    Poinssot, Ch.

    2002-01-01

    UO 2 (s): experimental approach and preliminary results on uranium oxide - water interface (J. Devoy), Preliminary results on studies on radiolysis effects on dissolution of UO 2 (E. Ekeroth, M. Jonnson); Session 5 - Modeling of the Spent Fuel Dissolution: tUO 2 dissolution and the effect of radiolysis (T. Lundstrom), Prediction of the effect of radiolysis (F. King), Experimental determination and chemical modeling of radiolytic processes at the spent fuel / water interface (E. Cera, J. Bruno, T. Eriksen, M. Grive, L. Duro); Session 6 - Influence of the Potential Evolution prior to the Water Access on IRF: Potential occurrence of α self-irradiation enhanced-diffusion (H.J. Matzke, T. Petit), Are grain boundaries a stable microstructure? (Y. Guerin), Modeling RN instant release fractions from spent nuclear fuel under repository conditions (C.Poinssot, L. Johnson, P. Lovera). (J.S.)

  10. DEVELOPMENT OF CRYSTALLINE CERAMICS FOR IMMOBILIZATION OF ADVANCED FUEL CYCLE REPROCESSING WASTES

    Energy Technology Data Exchange (ETDEWEB)

    Fox, K.; Brinkman, K.

    2011-09-22

    The Savannah River National Laboratory (SRNL) is developing crystalline ceramic waste forms to incorporate CS/LN/TM high Mo waste streams consisting of perovskite, hollandite, pyrochlore, zirconolite, and powellite phase assemblages. Simple raw materials, including Al{sub 2}O{sub 3}, CaO, and TiO{sub 2} were combined with simulated waste components to produce multiphase crystalline ceramics. Fiscal Year 2011 (FY11) activities included (i) expanding the compositional range by varying waste loading and fabrication of compositions rich in TiO{sub 2}, (ii) exploring the processing parameters of ceramics produced by the melt and crystallize process, (iii) synthesis and characterization of select individual phases of powellite and hollandite that are the target hosts for radionuclides of Mo, Cs, and Rb, and (iv) evaluating the durability and radiation stability of single and multi-phase ceramic waste forms. Two fabrication methods, including melting and crystallizing, and pressing and sintering, were used with the intent of studying phase evolution under various sintering conditions. An analysis of the XRD and SEM/EDS results indicates that the targeted crystalline phases of the FY11 compositions consisting of pyrochlore, perovskite, hollandite, zirconolite, and powellite were formed by both press and sinter and melt and crystallize processing methods. An evaluation of crystalline phase formation versus melt processing conditions revealed that hollandite, perovskite, zirconolite, and residual TiO{sub 2} phases formed regardless of cooling rate, demonstrating the robust nature of this process for crystalline phase development. The multiphase ceramic composition CSLNTM-06 demonstrated good resistance to proton beam irradiation. Electron irradiation studies on the single phase CaMoO{sub 4} (a component of the multiphase waste form) suggested that this material exhibits stability to 1000 years at anticipated self-irradiation doses (2 x 10{sup 10}-2 x 10{sup 11} Gy), but that

  11. Genesis and Multi-Episodic Alteration of Zircon-Bearing Chromitites from the Ayios Stefanos Mine, Othris Massif, Greece: Assessment of an Unconventional Hypothesis on the Origin of Zircon in Ophiolitic Chromitites

    Directory of Open Access Journals (Sweden)

    Argyrios Kapsiotis

    2016-11-01

    Full Text Available Several small chromium (Cr ore bodies are hosted within a unit of tectonically thinned dunite in the retired Ayios Stefanos mine of the western Othris ophiolite complex in Greece. Chromium ores consist of tectonically imprinted bodies of semi-massive to massive, podiform and lenticular chromitites composed of chromian spinel [Cr-spinel] with high Cr# [Cr/(Cr + Al = 0.51–0.66] and Mg# [Mg/(Mg + Fe2+ = 0.58–0.76], low Fe3+# [Fe3+/(Fe3+ + Fe2+ ≤ 0.43] and low TiO2 (≤0.21 wt % content. This composition is characteristic of Cr-spinels in equilibrium with melts of intermediate affinity between island-arc tholeiites (IATs and mid-ocean ridge basalts (MORBs. Several Cr-spinel crystals in these ores exhibit imperfect zones made up of spinel hosting oriented lamellae of Mg-silicates (mostly chlorite locally overgrown by porous domains along grain boundaries and fractures. From the Cr-spinel core to the lamellae-rich rim Cr#, Mg# and Fe3+# generally increase (0.68–0.87, 0.78–0.88 and 0.55–0.80, respectively, whereas from the core or the spinel zones with oriented lamellae to the porous domains Mg# and Fe3+# generally decrease (0.45–0.74 and ≤0.51, correspondingly. The lamellae-rich rims formed at oxidizing conditions, whereas the porous rims resulted from a later reducing event. Several tiny (≤30 μm, subhedral to anhedral and elongated Zr-bearing silicate mineral grains were discovered mainly along open and healed fractures cutting Cr-spinel. Most of the Zr-bearing silicate minerals (30 out of 35 grains were found in a chromitite boulder vastly intruded by a complex network of gabbroic dykes. The dominant Zr-bearing silicate phase is by far zircon displaying a homogeneous internal texture in cathodoluminescence (CL images. Raman spectroscopy data indicate that zircons have experienced structural damage due to self-irradiation. Their trace-element contents suggest derivation from a plagioclase-bearing, low-SiO2 intermediate to mafic

  12. Assessing absorbed dose heterogeneities for organ S-value calculation in mice

    International Nuclear Information System (INIS)

    Mauxion, T.; Villoing, D.; Marcatili, S.; Garcia, M.P.; Poirot, M.; Bardies, M.; Suhard, J.; Barbet, J.

    2015-01-01

    Full text of publication follows. Introduction and aim: S-values calculated according to the MIRD scheme strongly depend on the size of source/target regions and particle ranges (1). Several mean organ S-values were recently calculated for mice in the context of targeted radionuclide therapy and molecular imaging (2). However, the heterogeneity of energy deposition at the sub-organ level is seldom taken into account and the relevance of mean organ S-values is not systematically evaluated. This study aims at assessing spatial variations associated to mean S-values for small animals to estimate energy deposition heterogeneity at the sub-organ or voxel level. Materials and methods: a 29 g-mouse-model generated at high spatial sampling (200*200*200 μm 3 ) from the Moby software was used to calculate S-values for several radionuclides of interest (3). Monte Carlo simulations were performed with GATE (v6.2), in which specific corrections were implemented and validated to improve the accuracy of voxel energy-scoring. Mean S-values and standard deviations were calculated from 3D-voxel-based energy deposition maps for several source/target organ pairs. As the standard deviation associated to the mean S-value in a given target organ includes both spatial and statistical fluctuations, we simulated an increasing number of primary particles (typically from 10 6 to 10 10 ) to estimate the impact of relative statistical/spatial fluctuations for several source/target pairs. A spatial dispersion factor (HS-value for Heterogeneity of S-value) was obtained when the standard deviation converged to a stable value. Results: several HS-values calculated for source organs were significant in case of self-irradiation for all considered radionuclides, but remained very low as compared to values obtained for short and large source/target distances. For example, for 131 I sources located in the thyroid, S(thyroid - thyroid)=1.80*10 -9 Gy.Bq -1 .s -1 and HS(thyroid - thyroid)=3.09*10 -10 Gy

  13. Inhibition of the radiolytic hydrogen production in the nuclear waste of 'bitumen coated' type: study of the interaction between hydrogen and cobalt hydroxo-sulphide; Inhibition de la production d'hydrogene radiolytique dans les dechets nucleaires de type 'enrobes bitumineux': etude de l'interaction entre l'hydrogene et l'hydroxosulfure de cobalt

    Energy Technology Data Exchange (ETDEWEB)

    Pichon, C

    2006-11-15

    In the nuclear field in France, the bitumen is mainly used for the conditioning of the radioactive muds generated by the fuel reprocessing. However, the self-irradiation of the bitumen induces a production of hydrogen which generates safety problems. The comparison of various storage sites showed that the presence of cobalt hydroxo sulphide limited such a production. Consequently, this compound was regarded as an 'inhibitor of radiolytic hydrogen production'. However, the origin of this phenomenon was not clearly identified. In order to propose an explanation to this inhibition phenomenon, model organic molecules were used to represent the components of the bitumen. Irradiations were carried out by protons to simulate the alpha radiolysis. The organic molecules irradiations by a proton beam showed that cobalt hydroxo sulphide CoSOH, does not act as a hydrogenation catalyst of unsaturated hydrocarbons, nor as a radicals scavenger, but consists of a trap of hydrogen. Experiments of hydrogen trapping at ambient temperature were carried out according to two techniques: gravimetry and manometry. The solid was characterized before and after interaction with hydrogen (infrared and Raman spectroscopies, X-ray diffraction). The initial solid was composed of amorphous cobalt hydroxo sulphide and a minor phase of cobalt hydroxide. The gravimetry and manometry experiments showed that the maximum of hydrogen trapping capacity is equal to 0.59 {+-} 0.18 mole of hydrogen per mole of cobalt. After interaction with hydrogen, the Co(OH){sub 2} phase disappeared and a new solid phase appeared corresponding to Co{sub 9}S{sub 8}. These observations, as well as the analysis of the gas phase, made it possible to conclude with the following reaction (1): 9 CoSOH + 11/2 H{sub 2} = Co{sub 9}S{sub 8} + 9 H{sub 2}O + H{sub 2}S (1). Gravimetry experiments at temperatures between 50 and 210 C revealed the desorption of water but not of hydrogen sulphide. The absence of hydrogen

  14. Lethal Effect on Bacterium of Decay of Incorporated Radioactive Atoms ({sup 3}H, {sup 14}C, {sup 32}P); Effet Letal de la Desintegration d'Atomes Radioactifs ({sup 3}H, {sup 14}C, {sup 32}P) Incorpores dans une Bacterie

    Energy Technology Data Exchange (ETDEWEB)

    Apelgot, Sonia [Laboratoire Curie, Institut du Radium, Paris (France)

    1968-06-15

    The biological effect of decay of {sup 3}H, {sup 14}C and {sup 32}P incorporated into a bacterium depends on the nature of the organic molecule labelled, on the position of the isotope within it and on the isotope itself. In sum, results obtained to date show that: The decay of {sup 3}H atoms incorporated into certain macromolecules of a bacterium causes sterilization through ionization by the ss{sup -} particle emitted; transmutation is of negligible importance. This self-irradiation is comparable in effect with X-rays and is affected in a similar manner by the same factors: temperature, presence of a radioprotector, radiosensitivity of the strain. Decay of {sup 14}C or {sup 32}P atoms incorporated into bacterial DNA is lethal because of the transmutation effect; ionizations produced by emitted ss{sup -} particles may be disregarded. Survival curves for {sup 32}P transmutations depend on the experimental conditions. Some of the results obtained with {sup 32}P are similar to those obtained with X-rays, e.g. effects of temperature, radical capture and oxygen, while others are similar to those of u.v. light, e.g., effect of growth conditions. Comparative tests made with {sup 32}P indicate that the recoil energy of transmutation is not the phenomenon responsible for the lethal effect observed. Comparison of the results obtained after X-irradiation or decay of {sup 3}H or {sup 32}P incorporated into the DNA of bacteria of the same strain of E. coli shows that the efficiency of a {sup 32}P transmutation is about four times greater than that of an ionization produced at random within the same DNA. (author) [French] L'effet biologique de la desintegration de {sup 3}H, {sup 14}C et {sup 32}P incorpores dans une bacterie depend de la nature de la molecule organique marquee, de l'emplacement de l'isotope sur celle-ci et de la nature de l'isotope lui-meme. L'ensemble des resultats obtenus a ce jour montre que la desintegration des atomes de {sup 3}H incorpores dans certaines

  15. Spent fuel workshop'2002

    Energy Technology Data Exchange (ETDEWEB)

    Poinssot, Ch

    2002-07-01

    (M. Kelm), On the potential catalytic behavior of UO{sub 2}(s): experimental approach and preliminary results on uranium oxide - water interface (J. Devoy), Preliminary results on studies on radiolysis effects on dissolution of UO{sub 2} (E. Ekeroth, M. Jonnson); Session 5 - Modeling of the Spent Fuel Dissolution: tUO{sub 2} dissolution and the effect of radiolysis (T. Lundstrom), Prediction of the effect of radiolysis (F. King), Experimental determination and chemical modeling of radiolytic processes at the spent fuel / water interface (E. Cera, J. Bruno, T. Eriksen, M. Grive, L. Duro); Session 6 - Influence of the Potential Evolution prior to the Water Access on IRF: Potential occurrence of {alpha} self-irradiation enhanced-diffusion (H.J. Matzke, T. Petit), Are grain boundaries a stable microstructure? (Y. Guerin), Modeling RN instant release fractions from spent nuclear fuel under repository conditions (C.Poinssot, L. Johnson, P. Lovera). (J.S.)

  16. Rates and mechanisms of radioactive release and retention inside a waste disposal canister - in Can Processes

    Energy Technology Data Exchange (ETDEWEB)

    Oversby, V.M. (ed.) [and others

    2003-10-01

    the system that will not be present under long term disposal conditions. A simulation of long-term conditions can be done using uranium dioxide that contains a short-lived isotope of uranium, but this will not include the effects of fission product and higher actinide elements on the behaviour of the spent fuel. We designed a project that had as its objective to improve the scientific understanding of the processes that control release of radioactive species from spent fuel inside a disposal canister and the chemical changes in those species that might limit release of radioactivity from the canister. If the mechanisms that control dissolution of the fuel matrix, including self-irradiation effects, can be clarified, a more realistic assessment of the long-term behaviour of spent fuel under disposal conditions can be made. By removing uncertainties concerning waste form performance, a better assessment of the individual and collective role of the engineered barriers can be made. To achieve the overall objective of the project, the following scientific and technical objectives were set. 1. Measure the actual rate of matrix dissolution of uranium dioxide under oxidising and reducing conditions. 2. Measure the effect of alpha radiolysis on the dissolution rate of uranium dioxide under oxidising and reducing conditions. 3. Measure the dissolution rate of the matrix material of spent fuel and thereby determine the additional effects of beta and gamma radiation on uranium dioxide dissolution rate under oxidising and reducing conditions. 4. Measure the ability of actively corroding iron to reduce oxidised U(VI) to U(IV) when U is present as the complex ion uranyl carbonate. 5. Measure the rate of reduction of Np(V) species in the presence of actively corroding iron. 6. Calculate the expected equilibrium and steady state concentrations of U under the conditions of the experiments used for meeting objectives 1 through 3 and compare the calculated results with those measured in