Mass balance analysis of Th-233U based MSR (Molten-Salt Reactor) cycle (THORIMS-NES) transferred from present U-Pu based LWRs (Light Water Reactor)

Nuclear power can play a substantial role in countering global warming. There are still unsolved problems such as safety, nuclear proliferation, radioactive-waste under using U-Pu system. Transition from U-Pu LWR (Light Water Reactor) system to Th-233U MSR (Molten-Salt Reactor) system has been analysed in view of the utilization of fissile in form of Pu fuel salt applying the simplified FREGAT process to the spent fuel of LWR. AMSB (Accelerator Molten-Salt Breeder) was also applied as a fissile producer. All fissile in spent fuel can be used by Th-U MSR system so as not to remain storage of spent fuel after retirement of LWR system. The maximum capacity of Th-U MSR system will reach to about 20 x 103 GWe. However storage of spent fuel will remain for the case of rapid growth of Th-U MSR system even though the maximum capacity is large enough. AMSB will start operation about 20 years after the beginning of Th-U MSR system but the timing can be greatly advanced with the scenario of LWR system. Th-U MSR system can be implemented by using the fissile material in spent fuel from LWRs. Detailed assessment of other materials, performance of facilities, strategies of non-proliferation will be needed for the future improvement.