Transmutation of americium and curium using zirconia-based host materials.

Raison, P. E.

Technical Information Center Oak Ridge Tennessee

关键词: Americium;    Curium;    Transmutation;    Radioactive waste disposal;    Melting points;   

RP-ID  :  DE2001779791

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

We have investigated the incorporation of americium and curium in selected zirconia-based materials in conjunction with a research program at the 'Commissariat a l' Energie Atomique' that addresses transmutation of long-lived radioactive elements. Both cubic zirconia and pyrochlore oxides An(sub 2)Zr(sub 2)O(sub 7) (An = Am, Cm) are considered in the work reported here. The strategy proposed is to treat americium and curium together in the same transmutation process. There are several incentives for this approach. One is the radiotoxicity benefits while another is avoiding the difficult separation of Am and Cm. A third point is that curium must already be considered as it is generated in large amounts as a result of irradiating pure americium targets. Outlined here are our efforts to examine the behavior of Am and Cm in selected uranium-free hosts, which avoids the generation of additional actinide products. The general concept consists of irradiating the host targets for extended periods, which would be then disposed in a suitable repository (the so-called 'once through option'). The host matrix selected for Am and Cm must meet various criteria, such as a low neutron capture cross-section, a high melting point, phase stability, low oxygen potential, etc. Several potential candidates have been envisioned but the ultimate material may be a suitable 'rock-like' product able to sustain harsh irradiation conditions as well as the long-term repository environment. We initiated our studies for a host material with ZrO(sub 2)-based compounds and concluded that the cubic forms, obtained by stabilizing zirconia with about 25mol% of Y(sub 2)O(sub 3), should be attractive for this technological application. We have demonstrated that (Zr(sub 0.6)Y(sub 0.4))O(sub 1.8), or similar compositions, can incorporate significant amounts of americium dioxide by forming fluorite-type cubic solid solutions. It was also found that evolution of the cell parameters of these products is linear with the americium content.