Actinide diffusion in zirconium and the role of oxidation

AC

Etude de l'interaction entre l'hydroxosulfure de cobalt et l'hydrogène

National audienceLes effluents liquides générés lors du traitement du combustible nucléaire usé sont enrobés dans une matrice de bitume. L'hydroxosulfure de cobalt, CoSOH, est utilisé pour piéger l'hydrogène formé lors de la radiolyse de ces enrobés bitumineux. Des expériences de piégeage d'hydrogène ont été réalisées à température ambiante selon deux techniques (la gravimétrie et la manométrie) afin de comprendre le mode d'action de ce solide vis-à-vis de l'hydrogène. Les expériences de gravimétrie et de manométrie ont montré que la capacité maximale de piégeage d'hydrogène est égale à 0,59 ± 0,18 mole d'hydrogène par mole de cobalt. L'analyse des phases présentes après interaction avec l'hydrogène a permis de conclure à la réaction suivante : 9 CoSOH + 11/2 H2 = Co9S8 + 9 H2O + H2S. Du fait de la présence d'une phase minoritaire Co(OH)2 dans le solide initial, une deuxième réaction en parallèle, entre H2S produit et Co(OH)2 est envisagée, en accord avec les caractérisations effectuées et les bilans de masse mesurés

Study of Zircaloy-4 fuel cladding corrosion using ion beams - Application to long term disposal of nuclear wastes

AC

Hydrogen production during the irradiation of gaseous organic compounds: advantage of an extracted beam

ACE, Accélérateur, NIMBInternational audienceThis paper presents a fundamental study of the radiolysis of gaseous organic molecules induced by proton beam. For that purpose, a specific extracted beam line associated with a gas irradiation cell was set up on the 4 MV facility of the Institut de Physique Nucléaire of Lyon. The first experiments have been performed with gaseous alkanes and alkenes. The gaseous species formed during irradiation are analysed by an on-line gas chromatography instrument equipped with two detectors. In order to test our experimental faiclity, we have studied the influence of irradiation parameters (duration, beam intensity, pressure) on the production of hydrogen. In the case of propane, the radiolytic yield value of hydrogen G(H$_2$) is equal to 3.7 for total does in the range of 0.4 to 2.3 MGy at atmospheric pressure

EVIDENCE OF PRIMARY EVENTS IN 20Ne, 22Ne FRAGMENTATION FROM COINCIDENCE MEASUREMENTS IN 20, 22Ne + 93Nb REACTION AT 30 MeV/A

Evidence that primary ejectiles formation strongly depends on the projectile structure is given by comparison of 20Ne + 93Nb and 22Ne + 93Nb reactions at 30 MeV/A. Pick-up, stripping, break-up mechanism are identified using light particles-projectile fragments coïncidence measurements

Fission Enhanced diffusion of uranium in zirconia

This paper deals with the comparison between thermal and Fission Enhanced Diffusion (FED) of uranium into zirconia, representative of the inner face of cladding tubes. The experiments under irradiation are performed at the Institut Laue Langevin (ILL) in Grenoble using the Lohengrin spectrometer. A thin $^{235}UO\_2$ layer in direct contact with an oxidized zirconium foil is irradiated in the ILL high flux reactor. The fission product flux is about 10$^{11}$ ions cm$^{-2}$ s$^{-1}$ and the target temperature is measured by an IR pyrometer. A model is proposed to deduce an apparent uranium diffusion coefficient in zirconia from the energy distribution broadening of two selected fission products. It is found to be equal to 10$^{-15}$ cm$^2$ s$^{-1}$ at 480$\circ$C and compared to uranium thermal diffusion data in ZrO$\_2$ in the same pressure and temperature conditions. The FED results are analysed in comparison with literature data

Zirconium oxidation under high energy heavy ion irradiation

This paper concerns the study of zirconium oxidation under irradiation with high energetic Xe ions. The irradiations were performed on the IRRSUD beam line at GANIL (Caen). The oxygen partial pressure was fixed at 10$^{-3}$ Pa and two temperature conditions were used, either 480$\circ$C reached by Joule effect heating or 280$\circ$C due to Xe energy deposition. Zirconia was fully characterized by Rutherford Backscattering Spectrometry, Transmission Electron Microscopy and Grazing Angle X-ray Diffraction. Apparent diffusion coefficients of oxygen in ZrO2 were determined from these experiments by using a model which takes into account a surface exchange between oxygen gas and the ZrO2 surface. These results are compared with thermal oxidation data