Development of fundamental technology of pyro-partitioning and transmutation of long lived nuclides

Fundamental technology of pyro-partitioning of transuranium elements (TRUs) and transmutation by a metallic fuel FBR is developed. It is clarified on the pretreatment process that the high level liquid waste can be converted to oxide forms by micro-wave heating method and the oxides to chlorides by pouring chlorine gas. Concerning the pyrometallurgical process consisting of chemical reduction and electrorefining processes, the thermodynamic data, such as activity coefficient, were obtained by the electrochemical method. In addition, it was found by experiments simulated with rare earths that TRUs as well as rare earths can be reduced in the cadmium phase in the molten chloride and molten cadmium system. As for the transmutation technology, it was analysed that a higher transmutation rate of TRUs was attained in a metallic fuel FBR than in an oxide fuel FBR. It is suggested from the fuel fabrication study that each 2 wt% of TRUs and rare earths can be mixed in a fuel alloy. Moreover, the concept of fuel pin with TRUs and the core design are proposed. (author) 93 refs