Extraction behavior of TRU elements in the nuclear fuel reprocessing

The extraction behaviors of uranium, plutonium and other nuclides in the fuel reprocessing have been investigated to study the capability of confining the radioactivity in the PUREX process. Reprocessing tests using spent fuel of 44 GWd/t have been carried out in alpha-gamma cell equipped with reprocessing equipment in NUCEF (Nuclear Fuel Cycle Safety Engineering Research Facility). The reprocessing equipment consists of a dissolver, six mixer-settlers, off-gas treatment and aqueous waste treatment systems. The mixer-settler were assigned to diluent washing, co-decontamination, FP scrub, U recovery and U/Pu partitioning steps. The concentration profiles of nitric acid, U, Pu, neptunium and americium were obtained under normal operation of PUREX flow sheet. The distribution fractions of the nuclides were calculated by the concentrations and the flow rates of organic and aqueous solutions. It was found that U and Pu were recovered from the spent fuel dissolver solution and were well separated from each other. About 10% of Np was distributed into the raffinate solution in the co-decontamination step. Almost all of the Am migrated to the raffinate solution. The experimental results were used for the evaluation of the simulation code ESSCAR (Extraction process simulation code) developed for the safety analysis of reprocessing. (author)