Influence of the monovalent M cation on the M_(2+x)Th_(2-x)Nd_x(C_2O_4)_5?nH_2O solid solution domain

摘要

An optimized fuel cycle option for Generation III/IV systems could be co-management of the minor actinides in an integrated closed fuel cycle. This approach implies separating these actinides from the fission products, and then converting them to solid forms to re-fabricate fresh fuel. Oxalate compounds are well known for this purpose. Co-management process is based on the oxalic co-precipitation of An(IV) and An(III) in a mixed oxalate as, for example, the hexagonal phase, M_(2+x)~+An~(IV)_(2-x)An_x~Ⅲ(C_2O_4)_5?nH_2O with M~+ representing a singly-charged cation. A study of the Th-Nd-M~+ hexagonal oxalate systems has been carried out in order to understand the charge compensation mechanisms implicated in the formation of mixed oxalates systems.