EXTRACTION AND EXTRACTION CHROMATOGRAPHIC-SEPARATION OF MINOR ACTINIDES FROM SULFATE BEARING HIGH-LEVEL WASTE SOLUTIONS USING CMPO

Bench-Scale studies on the partitioning and recovery of minor actinide s from the actual and synthetic sulphate-bearing high level waste (SBH LW) solutions have been carried out by giving two contacts with 30% TB P to deplete uranium content followed by four contacts with 0.2M CMPO + 1.2M TBP in dodecane. The acidity of the SBHLW solutions was about 0 .3M. In the case of actual SSHLW, the final raffinate contained about 0.4% alpha-activity originally present in the HLW whereas with synthet ic SBHLW the or-activity was reduced to the background level, Ce-144 i s extracted almost quantitative in the CMPO phase, Ru-106 about 12% an d Cs-137 is practically not extracted at all. The extraction chromatog raphic column studies with synthetic SBHLW (after two TBP contacts) ha s shown that large volume of waste solutions could be passed through t he column without break-through of actinide metal ions. Using 0.04M HN O3 > 99% Am(III) and rare earths could be eluted/stripped. Similarly > 99% Pu(IV) and U(VI) could be eluted/stripped using 0.01M oxalic acid and 0.25M sodium carbonate, respectively, In the presence of 0.16M SO 42- (in the SBHLW) the complex ions AmSO4+. UO2SO4, PuSO42+ and Pu(SO4 )(2) were formed in the aqueous phase but the species extracted into t he organic phase (CMPO+TBP) were only the nitrate complexes Am(NO3)(3) . 3CMPO, UO2(NO3)(2) . 2CMPO and Pu(NO3)(4) . 2CMPO. A scheme for the recovery of minor actinides from SBHLW solution with two contacts of 30% TBP followed by either solvent extraction or extraction chromatogr aphic techniques has been proposed.