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Thermodynamic model of the oxidation of Ln-doped UO₂.

ABSTRACT: Ln-doped UO₂ is often considered as a model system of spent nuclear fuel (SNF) helping to reveal effects of fission and activation products on its chemical stability. Comparing thermodynamics of UO₂-UO₃ and LnO_1.5-UO₂-UO₃ systems provides a means to understand the phenomenon of an increased resistivity of Ln-doped UO₂ to oxidation in air relative to pure UO₂. Here a thermodynamic model is developed and is applied to investigate detailed phase changes occurring along the oxidation of Ln-doped fluorite to U₃O₈. The study proposes that an enhanced resistivity to oxidation of Ln-doped UO₂ is likely caused by a thermodynamically driven partitioning of Ln between a fluorite-type phase and a U₃O₈ polymorph, which at ambient temperatures becomes hindered by slow diffusion.

SUBMITTER: Vinograd VL

PROVIDER: S-EPMC10589314 | biostudies-literature | 2023 Oct

REPOSITORIES: biostudies-literature

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Thermodynamic model of the oxidation of Ln-doped UO2.

Vinograd V L VL Bukaemskiy A A AA Deissmann G G Modolo G G

Scientific reports 20231020 1

Ln-doped UO2 is often considered as a model system of spent nuclear fuel (SNF) helping to reveal effects of fission and activation products on its chemical stability. Comparing thermodynamics of UO2-UO3 and LnO1.5-UO2-UO3 systems provides a means to understand the phenomenon of an increased resistivity of Ln-doped UO2 to oxidation in air relative to pure UO2. Here a thermodynamic model is developed and is app ...[more]

PMID: 37863981

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