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

高塩濃度溶液中のトリウムとウランの分離への抽出クロマトグラフィの適用

藤原 亜佐子 ; 亀尾 裕 ; 星 亜紀子 ; 原賀 智子   ; 中島 幹雄

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

UTEVA樹脂を用いる抽出クロマトグラフィを多元素を含む対照試料と模擬廃棄物の溶融固化体を溶解して作製した試料に含まれるThとUの分離に適用した。硝酸濃度1Mから5Mの対照試料中のThとUは、UTEVA樹脂に抽出され、0.1Mの硝酸と0.05Mのシュウ酸を含む溶液によって回収され、結果としてほかの金属元素から分離された。溶融固化体の試料中のウランは対照試料と同様の溶離挙動を示した。一方、トリウムは硝酸濃度5Mの試料からは抽出されたが、硝酸濃度1Mの試料からは抽出されなかった。フッ化物イオンがThの抽出を妨害していると考え、Thよりもフッ化物イオンとの安定度定数が大きいAlやFeの硝酸塩を添加したところ、硝酸濃度1Mの試料からもThが抽出された。

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.