Abstract
A continuous counter-current experiment using mixer-setters was performed to evaluate the separation performance of N,N-dialkylamides for U and Pu in the presence of their degradation products. The experiment consisted of two cycles: the first cycle employed N,N-di(2-ethylhexyl)-2,2-dimethyl- propanamide (DEHDMPA) for selective extraction of U(VI) and the second cycle employed N,N-di(2-ethylhexyl)butanamide (DEHBA) for co-extraction of U(VI) and Pu(IV). DEHDMPA extracted most of the U(VI) from the feed, and the ratio of U(VI) recovered from the U fraction was 99.57%. DEHDMPA hardly extracted Pu(IV), and the decontamination factor for U with respect to Pu in the U fraction was 1.1 × 104. The raffinate from the first cycle was used as the feed for the second cycle, and almost all the U(VI) and Pu(IV) were co-extracted by DEHBA. The degradation products of the extractants had no detrimental effect on the two-phase separation and operation of the mixer-settlers.
