New Insight into Self-Irradiation Effects on Local and Long-Range Structure of Uranium-Americium Mixed Oxides (through XAS and XRD)

作者：Lebreton Florent; Martin Philippe M; Horlait Denis; Bes Rene; Scheinost Andreas C; Ros**erg Andre; Delahaye Thibaud^*; Blanchart Philippe

来源：Inorganic Chemistry, 2014, 53(18): 9531-9540.

DOI：10.1021/ic500681k

Uranium-americium mixed oxides could be used as transmutation targets to lower Am inventory in spent nuclear fuels. Due to Am-241 activity, these materials are subjected to alpha-self-irradiation which provokes crystallographic disorder. Previous studies on U-Am mixed oxides gave first insight into alpha-radiation tolerance of these compounds, but have never been carried out for more than a year, whereas these compounds might be stored up to a few years between fabrication and irradiation. In this work, we study effects of self-irradiation on the structure of U1-xAmxO2 +/-delta solid solutions (x = 0.15 and 0.20) aged 3 to 4 years. Especially, X-ray diffraction and X-ray absorption spectroscopy are combined to observe these effects from both long-range and local perspectives. Results show that the fluorite-type structure of U-Am mixed oxides withstands Am-241 alpha-irradiation without major damage. Despite the increase of interatomic distances and crystallographic disorder observed during the first months of storage, the present results show that a steady state is then reached. Thus, no detrimental factors have been identified in this study in terms of structural damage for several-year storage of U1-xAmxO2 +/-delta pellets before irradiation. Furthermore, comparison between long-range and local evolution suggests that alpha-self-irradiation-induced defects are mainly located in low-ordered domains. Based on literature data and present results, the steady state appears related to the equilibrium between radioinduced defect formation and material self-healing.

• 出版日期2014-9-15
• 单位中国地震局