Dissolution of powdered spent fuel and U crystallization from actual dissolver solution for "NEXT" process development

"NEXT"プロセス開発のための粉化照射済燃料の溶解及び実溶解液からのU晶析

野村 和則  ; 比内 浩; 中原 将海; 鍛治 直也; 紙谷 正仁 ; 大山 孝一 ; 佐野 雄一   ; 鷲谷 忠博 ; 小巻 順

Nomura, Kazunori; Hinai, Hiroshi; Nakahara, Masaumi; Kaji, Naoya; Kamiya, Masayoshi; Oyama, Koichi; Sano, Yuichi; Washiya, Tadahiro; Komaki, Jun

U crystallization process from the dissolver solution of the spent nuclear fuel has been developed as one of the key essential technologies for the "NEXT" process development. Since several tens % of U is supposed to be recovered at the crystallization process, it is expected to reduce the total mass of nuclear material to be treated in the solvent extraction process. For the U crystallization, it is desirable to prepare the dissolver solution of relatively high U concentration. Although the conventional dissolution method needs significantly long dissolution time in order to obtain the dissolver solution of high U concentration with high dissolution ratio, it is expected the effective dissolution is achieved by powderizing the spent fuel. The beaker-scale experiments on the effective powdered fuel dissolution and the U crystallization from dissolver solution with the irradiated MOX fuel from the experimental fast reactor "JOYO" were carried out at the Chemical Processing Facility (CPF) in Tokai Research and Development Center. The powdered fuel was effectively dissolved into the nitric acid solution and the results were compared with the calculation results of the simulation model. In the U crystallization trials, U crystal was obtained from the actual dissolver solution without any addition of reagent.