PXRD characterization of uranium and plutonium peroxide and hydroxide phases of interest for MOx fuel preparation

In order to develop alternative pathway for the synthesis of uranium and plutonium oxide mixture for MOx fuel preparation and to evaluate the behavior of representative surrogate systems for spent nuclear fuel, several conversion processes are under study. Among them, the hydrothermal processes of uranium and plutonium peroxide conversion and the hydroxide pathway are considered as promising methods to achieve these objectives. The aim of this proposal will be to achieve the crystallographic characterization of some compounds of interests for these syntheses methods. On the one hand, the structures of the actinide(IV) peroxide phases are still poorly identified and require advanced characterization. The actinide oxide obtained thanks to hydrothermal methods would also need characterization. On the other hand, the uranium/plutonium phases obtained thanks to hydroxide route of coprecipitation require high resolution characterization to identify the potential formation of solid solution.为开发用于制备混合氧化物（MOx fuel）燃料的铀钚混合氧化物合成替代路径，并评估乏核燃料（spent nuclear fuel）典型替代体系的行为，目前已有多项转化工艺处于研究阶段。其中，铀钚过氧化物转化水热工艺与氢氧化物路径被视为实现上述目标的极具潜力的方案。本提案的研究目标为，对上述合成方法所涉及的部分目标化合物开展晶体学表征。 一方面，四价锕系元素（actinide(IV)）过氧化物相的结构仍未得到充分明确，亟需开展精细化表征；通过水热工艺制备得到的锕系氧化物同样需要完成表征工作。另一方面，通过氢氧化物共沉淀路径得到的铀/钚相，需借助高分辨表征手段以识别其潜在的固溶体生成情况。