Separation of Cs-137, Sr-90, and Th-232 in Aqueous Solution by Using a Multistage Countercurrent Batch Contactor Ion-Exchange System

Abstract

The radioisotopes Cs-137, Sr-90, and Th-232, in simulated high level nuclear liquid waste, were recovered and sequentially separated by using an 8-stage flask simulation of a multistage countercurrent batch contactor (MCBC) ion-exchange system. The solution normality ratio used for the three ions Cs:Sr:Th was 1:l:l.The solution was contacted for 2 h with resin Dowex HCR-W2 initially in the H' form. The obtained recovery efficiency of the MCBC and the purity of the separated ions for the three ions were 77 and 60% for Cs', 64 and 93% for Sr2+, and 99 and 65% for Th", respectively. INTRODUCTIONThe high level liquid waste nitrate solution from nuclear fuel reprocessing operations contains recyclable fissionable materials (U, Pu), Np, and several major soluble solid fission products (I).The waste is separated by a solvent extraction process to recover the recyclable fissile materials and Np, and then the useful radioactive nuclides are recovered by an ion-exchange or solvent extraction process (1-3) for use as special purpose radionuclides (I, 4). The recovery also reduces the disposal cost of the remaining waste as well as reducing the environmental hazards associated with the waste (4). During solvent extraction, the fissile materials and the bulk of the actinides contained in the organic phase are recovered, leaving the fission products, including Cs-137 and Sr-90, contaminated with small amounts of the actinide elements left behind in the