Development of partitioning of high-level radioactive waste

Research and development of partitioning methods has been carried out to separate transuranic elements, Sr, Cs, etc., from high-level waste liquid and to treat each of them appropriately. This report reviews recent activities for research and development of partitioning methods being performed in various areas in the world. In the review, 'partitioning' refers not only to the separation and transmutation of transuranic elements but also to the isolation of ⁹⁹Sr and ¹³⁷Cs from high-level liquid wastes. In the U.S., partitioning is planned for high-level wastes from reprocessing plants and α-wastes from reprocessing and fuel processing plants. The flow of transuranic elements during the partitioning process and the procedure for separating transuranic elements from high-level liquid wastes are described. In Europe, research and development of partitioning and transmutation processes is carried out by the Joint Research Centre. TBP extraction, HDEHP extraction and oxalate precipitation have been studied by the Centre to provide methods for partitioning. In Japan, a process has been developed to separate elements in high-level liquid waste into three groups: transuranic elements, Sr-Cs elements and others. A study is currently under way to provide a process to divide wastes into four groups. (Nogami, K.)