Conceptual design study of the powdered fuel dissolver

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鷲谷 忠博 ; 樋口 英俊; 佐野 雄一   ; 青瀬 晋一

Washiya, Tadahiro; Higuchi, Hidetoshi; Sano, Yuichi; Aose, Shinichi

先進湿式再処理の晶析工程で必要となる高濃度溶解液を効率よく調整するための技術として,粉体化燃料を用いた高効率溶解の技術開発が進められている。燃料の粉体化による溶解速度の向上が期待される一方で,反応性が高く,ハンドリング性に難のある粉体燃料を効率的,且つ,安全に溶解できる専用の溶解槽の開発が必要であった。本報では,粉体溶解槽の開発について,これまでに実施してきた構造検討,コールド要素試験等の内容を報告する。

Japan Nuclear Cycle Development Institute (JNC) has been developing the crystallization technology for the advanced aqueous reprocessing plant to realize the FBR fuel cycle. The crystallization process is applied in front of the extraction process for removing large amount of uranium and reducing the throughput of extraction process. The crystallization process requires high concentrated dissolution (500g-HM/L) to mitigate the cooling conditions. The powdered fuel dissolution is a promising technology to obtain the high concentrated dissolution. Hot experiments of the powdered fuel dissolution were carried out at CPF to verify the dissolution speed and characteristics. As result, the speed is ten times faster than conventional sheared fuel. For the powdered fuel dissolution, particle handling is a key issue to prevent piling up of the fuel particles on the dissolver bottom and elutriation rate to the off gas system. In this paper, functional requirements and subjects for the powdered fuel dissolution were discussed. And an innovative dissolver design based on the cylindrical stirring type dissolver was proposed for reliable continuous dissolver system with the powdered fuel. Some engineering scale test and computer code evaluations were carried out to verify the dynamic performance of simulated fuel particles and water in the dissolver design.