Application of extraction chromatography to the separation of thorium and uranium dissolved in a solution of high salt concentration

Fujiwara, Asako ; Kameo, Yutaka ; Hoshi, Akiko ; Haraga, Tomoko   ; Nakashima, Mikio

Extraction chromatography with UTEVA resin was applied to separation of Th and U from control solutions prepared from a multi-element control solution and from sample solutions of solidified simulated waste. Thorium and U in control solutions with 1 to 5 M HNO were extracted with UTEVA resin and recovered with a solution containing 0.1 M HNO and 0.05 M oxalic acid to be separated from the other metallic elements. Extraction behavior of U in the sample solutions was similar to that in the control solutions, but extraction of Th was dependent on the concentration of HNO. Thorium was extracted from 5 M HNO sample solutions but not from 1 M HNO sample solutions. We conjecture that thorium fluoride formation interferes with extraction of Th. Addition of Al(NO) and Fe(NO), which have a higher stability constant with fluoride ion than Th does with it improved extractability of Th from 1 M HNO sample solution.