Synchrotron Diffraction Study of the Isothermal Oxidation of Uranium Dioxide at 250℃

摘要

The structural evolution of UO_2 during its oxidation to U_3O_8 at 250℃ in air was studied by in-situ synchrotron X-ray diffraction on the D2AM-CRG beamline at ESRF. The aim of this study is to determine the phases that are likely to appear during the long-term storage of spent nuclear fuel. Our results are in disagreement with the literature in which the existence of an intermediate cubic phase is not reported. Instead, an α-U_3O_7 tetragonal phase (c/a < 1) was mentioned but not definitively observed. These previous interpretations may have been the result of poor instrumental resolution.