Uranium and plutonium extraction by -dialkylamides using multistage mixer-settler extractors

Ban, Yasutoshi  ; Hotoku, Shinobu ; Tsutsui, Nao  ; Suzuki, Asuka; Tsubata, Yasuhiro   ; Matsumura, Tatsuro  

A continuous counter-current experiment was carried out to demonstrate the validity of a process using -dialkylamides for recovering U and Pu. This process consisted of two cycles, and the 1st cycle and the 2nd cycle employed -di(2-ethylhexyl)-2,2-dimethylpropanamide and -di(2-ethylhexyl)butanamide as extractants, respectively. The feed solution for the 1st cycle was 5.1 mol/dm (M) nitric acid containing 0.92 M U, 1.6 mM Pu, and 0.6 mM Np. The raffinate collected in the 1st cycle was used as the feed for the 2nd cycle. The ratios of U recovered in the U fraction and U-Pu fraction were 99.1% and 0.8%, respectively. The ratio of Pu recovered in the U-Pu fraction was 99.7%. The concentration ratio of U with respect to Pu in the U-Pu fraction was 9, and this indicated that Pu was not isolated. The decontamination factor of U with respect to Pu in the U fraction was obtained as 4.510. These results supported the validity of the proposed process.