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

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• 作者：Florent Lebreton ; Philippe M. Martin ; Denis Horlait ; Ren茅 B猫s ; Andreas C. Scheinost ; Andre Rossberg ; Thibaud Delahaye ; Philippe Blanchart
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：September 15, 2014
• 年：2014
• 卷：53
• 期：18
• 页码：9531-9540
• 全文大小：608K
• ISSN：1520-510X

文摘

Uranium鈥揳mericium mixed oxides could be used as transmutation targets to lower Am inventory in spent nuclear fuels. Due to ²⁴¹Am activity, these materials are subjected to 伪-self-irradiation which provokes crystallographic disorder. Previous studies on U鈥揂m mixed oxides gave first insight into 伪-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 U_1鈥?i>xAm_xO_2卤未 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鈥揂m mixed oxides withstands ²⁴¹Am 伪-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 U_1鈥?i>xAm_xO_2卤未 pellets before irradiation. Furthermore, comparison between long-range and local evolution suggests that 伪-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.