ジルコニウム廃棄物のリサイクル技術の開発

Abstract

Spent zircaloy cladding and channel boxes from Boiling Water Reactors (BWR), which constitute spent zircaloy waste, are not recycled in spent fuel reprocessing plants. The zircaloy waste should be pressed and packed into cans for radioactive waste disposal. The disposal costs of zircaloy waste were estimated to be about 440 billion yen because they require the same deep disposal as the high-β•γ waste generated from the spent fuel reprocessing plant at Rokkasho in Aomori Prefecture. The recovery and recycle of expensive zirconium from the spent zircaloy waste is possibly one of the most effective solutions to the problem regarding environmental issues in the nuclear field. Electrorefining in molten salts for the zirconium recovery process is a promising technique, which has high decontamination factors (DFs) and reduces the secondary waste. This study aims to confirm the feasibility of the zirconium recovery process from the spent channel boxes after eliminating radioactive nuclides and to illustrate the economic feasibility of zirconium recycle. Zirconium was deposited on the cathode and recovered by electrorefining in molten salts to separate radioactive cobalt and antimony. The zirconium recycle cost was estimated to be about 1/10 of direct disposal cost.