Treatment of high-level radioactive waste arising from pyroprocessing and its waste form

乾式再処理工程から排出される高レベル放射性廃棄物の処理とその固化体について

天本 一平

Amamoto, Ippei

乾式再処理工程から排出される使用済み電解質は高レベル放射性廃棄物に区分されるため、経済性や環境負荷低減化に鑑みて、発生する容量を低減化させる必要があり、また、適切な固化体を想定しておく必要がある。本報では、世界各国で開発されているさまざまな使用済み電解質の処理方法や固化方法を紹介する。特に、鉄リン酸塩ガラスに注目して、これをFP除去用の収着材として用いる可能性について概説するとともに、鉄リン酸塩ガラスを媒体と用いたガラス固化体の性能について、研究成果を述べている。

In this paper, the author has briefly introduced the development of pyroprocessing, highlighting the spent electrolyte treatment from the viewpoint of economical and environmental load reduction. The zeolite sorption method developed in USA is currently most progressive technique. There are other methods which use phosphates to treat the spent electrolyte, among them three are presented here, i.e., the phosphates precipitation method developed by RIAR, the GRSS method using SAP by KAERI, and the phosphate conversion method by JAEA. In the phosphate conversion method, the iron phosphate glass (IPG), which possesses unique properties, is employed for FP separation and FP immobilization. From preliminary experiments, it found that the IPG could separate insoluble FP in the spent electrolyte when used as a filtration medium. In addition, when used as a sorbent, it could remove the soluble FP. The IPG is regarded as a potential effective material to treat FP as well as the glass medium.