Skip to Main content Skip to Navigation
Journal articles

Actinide Oxidation State and O/M Ratio in Hypostoichiometric Uranium–Plutonium–Americium U$_{0.750}$Pu$_{0.246}$Am$_{0.004}$O$_{2-x}$ Mixed Oxides

Abstract : Innovative americium-bearing uranium–plutonium mixed oxides U$_{1–y}$Pu$_y$O$_{2–x}$ are envisioned as nuclear fuel for sodium-cooled fast neutron reactors (SFRs). The oxygen-to-metal (O/M) ratio, directly related to the oxidation state of cations, affects many of the fuel properties. Thus, a thorough knowledge of its variation with the sintering conditions is essential. The aim of this work is to follow the oxidation state of uranium, plutonium, and americium, and so the O/M ratio, in U$_{0.750}$Pu$_{0.246}$Am$_{0.004}$O$_{2-x}$ samples sintered for 4 h at 2023 K in various Ar + 5% H$_2$ + z vpm H$_2$O (z = ∼15, ∼90, and ∼200) gas mixtures. The O/M ratios were determined by gravimetry, XAS, and XRD and evidenced a partial oxidation of the samples at room temperature. Finally, by comparing XANES and EXAFS results to that of a previous study, we demonstrate that the presence of uranium does not influence the interactions between americium and plutonium and that the differences in the O/M ratio between the investigated conditions is controlled by the reduction of plutonium. We also discuss the role of the homogeneity of cation distribution, as determined by EPMA, on the mechanisms involved in the reduction process.
Complete list of metadatas

https://hal-cea.archives-ouvertes.fr/cea-02528980
Contributor : Florent Lebreton <>
Submitted on : Thursday, April 2, 2020 - 9:32:30 AM
Last modification on : Monday, May 25, 2020 - 4:51:21 PM

Identifiers

Collections

Citation

Romain Vauchy, Renaud Belin, Anne-Charlotte Robisson, Florent Lebreton, Laurence Aufore, et al.. Actinide Oxidation State and O/M Ratio in Hypostoichiometric Uranium–Plutonium–Americium U$_{0.750}$Pu$_{0.246}$Am$_{0.004}$O$_{2-x}$ Mixed Oxides. Inorganic Chemistry, American Chemical Society, 2016, 55 (5), pp.2123-2132. ⟨10.1021/acs.inorgchem.5b02533⟩. ⟨cea-02528980⟩

Share

Metrics

Record views

47