Demonstration of denitration and chlorination process using real high level liquid waste

The pyropartitioning process separates the actinide elements including the minor actinide elements from the high-level liquid waste generated at the Purex reprocessing of spent LWR fuel and introduces them to metallic fuel cycle. Since the separation of the actinide elements from the fission product elements is performed in molten chloride salt/liquid metal system, the actinide and fission product elements in the high-level liquid waste must be converted to the chlorides as the first step of the pyropartitioning process. In order to demonstrate the conversion of the actinide and fission product elements to the chlorides, a series of denitration and chlorination test using 520g of real high-level liquid waste, which contains 8400 micro-g/g of uranium, 600 micro-g/g of transuranium elements, and 2000 micro-g/g of fission products including 870 micro-g/g of rare-earth elements, was performed. The results of the tests are as following; 1) The entire denitration product of the high-level liquid waste was successfully recovered from the containing crucible, which is made of stainless steel. No damage was found on the inside surface of the crucible. During the denitration, small amount of ruthenium was evaporated. 2) After the chlorination of the denitrated material, only 1 to 5% of each actinide element remained as the water insoluble material in the salt phase, which is assumed to be oxide. And almost all of the actinide elements were converted to water soluble material in the salt phase, which are assumed to be chloride. Additionally, almost all of the rare-earth fission product, alkaline-earth fission product, and alkaline-metal fission product elements were also converted to water soluble material in the salt. Some of the fission products such as molybdenum and zirconium were evaporated during the chlorination. 3) Since nearly 100% of each actinide element was recovered as the chloride, the denitration and chlorination were successfully demonstrated. (author)