[Research Activities]

High-level radioactive liquid waste (HLLW) produced in a reprocessing plant contains minor actinides (MA; Np, Am, Cm) besides numerous fission products. It is well known that most of MA nuclides are alpha-emitters with the long half-lives and/or large decay heat. From the viewpoint of mitigating the long-term toxicity of radioactive waste and the burden of final disposal of radioactive waste, an advanced fuel cycle with partitioning and transmutation (PT), in which MA are partitioned from HLLW and burnt in a transmutation system such as a fast reactor (FR) or accelerator driven system (ADS), has been investigated.

Our group has been carrying out the R&D on the preparation of transuranium (TRU) compounds such as the oxide, nitride, chloride and alloy, the measurement of thermal properties, the fuel fabrication technology, the evaluation of irradiation behavior, and the pyrochemical process for spent fuel treatment in order to support the development of an advanced fuel cycle with PT.

Furthermore, basic properties on the TRU compounds have been measured by use of Moesbauer spectroscopy, nuclear magnetic resonance (NMR), X-ray absorption fine structure (XAFS) and so on under collaboration with domestic partners.