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Apport de l'étude de matériaux modèles U1-xPuxO2 à la compréhension des mécanismes d'altération des combustibles UOx et MOx en stockage géologique

Abstract : The effects of the geological disposal environment on the leaching of the oxide matrices of UOx and MOx fuels were investigated following a step-by-step procedure: carbonated water, synthetic porewater of the Collovo-Oxfordian (COx) argillite, synthetic porewater in presence of iron or argillite samples. Two types of alpha-emitting materials were considered, UO2 pellets doped with a low Pu content, and pellets of homogenous U0.73Pu0.27O2 MOx fuel. The experimental protocols did not show any significant effect of the argillite on the UO2alteration. Plutonium decreased the oxidative dissolution of U0.73Pu0.27O2 and enhanced the disproportionation of the H2O2 produced by water radiolysis. The dissolution of the MOx matrix decreased in COx water. It was strongly inhibited in presence of iron which anoxic corrosion liberated Fe2+ in solution that fully reacted with the radiolytic H2O2, leading to magnetite precipitation on the pellet surface. Geochemical (CHESS code) and reactive transport (HYTEC code) models, which were developed for the homogeneous MOx alteration,correctly simulated the main experimental data and the underlying mechanisms. The alteration processes of UOx and MOx matrices were found to be very similar under the present environmental conditions.
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https://pastel.archives-ouvertes.fr/tel-03191303
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Submitted on : Wednesday, April 7, 2021 - 9:15:02 AM
Last modification on : Friday, April 9, 2021 - 3:11:46 AM

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2020UPSLM061-archivage.pdf
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  • HAL Id : tel-03191303, version 1

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Valentin Kerleguer. Apport de l'étude de matériaux modèles U1-xPuxO2 à la compréhension des mécanismes d'altération des combustibles UOx et MOx en stockage géologique. Ingénierie de l'environnement. Université Paris sciences et lettres, 2020. Français. ⟨NNT : 2020UPSLM061⟩. ⟨tel-03191303⟩

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