高速増殖炉燃料再処理における新脱被覆システムの開発

Development of New Decladding System in the Reprocessing Process for FBR Fuel

山田 誠也; 鷲谷 忠博 ; 竹内 正行 ; 小泉 務; 青瀬 晋一

Yamada, Seiya; Washiya, Tadahiro; Takeuchi, Masayuki; Koizumi, Tsutomu; Aose, Shinichi

酸化物燃料の乾式再処理及び湿式再処理への適用が可能な脱被覆技術として、破砕工程、ハル燃料分離工程及びハル洗浄工程から構成される新しい前処理システムを開発した。本システムは高Pu富化度の高速炉燃料にも適用可能なシステムであり、燃料の粉砕化が必須の乾式再処理プロセスでは枢要システムと考えられる。本報告では、この新たな脱被覆システム及び各工程における新型機器の概要について報告する。

The application of the fluoride volatility process in the reprocessing of fuel from the fast breeder reactor is regarded as one of the economical methods. Plutonium hexafluoride (PuF6), however, reacting with fluorine (F2) and plutonium dioxide (PuO2) as the raw material, is in an unstable condition and tends to remain as a solid compound in the process after decomposing into plutonium tetrafluoride (PuF4). Suitable conditions should be established for the practical use of this process. One of them is to enhance the stability of PuF6. The behaviour of plutonium fluorination and relevant chemical reactions were investigated by referring to sundry literature and by thermodynamic calculation. It was then compared with recent data from laboratory scale experiments for this paper. Results from the theoretical analysis agreed with experimental observation that PuF6 could be formed stably under a high temperature condition (approx.1000 K) with over supply of figher concentration of F2.