Study of natural uranium utilization in a heavy water moderated molten salt reactor

Heavy water moderated molten salt reactor (HWMSR) is a newly proposed molten salt reactor. It adopts heavy water as the moderator and molten salt dissolved with actinide elements as the fuel and coolant as well. These unique features endow HWMSR a high neutron economy as performed in CANDU (CANada Deuterium Uranium) pressure tube heavy water reactor and a capability to implement the processes of online refueling and reprocessing as done in the conventional MSRs, making natural uranium (NU) utilization and together with U-233 production become feasible. The obtained results in this study demonstrate that the fuel utilization efficiency of HWMSR with NU fuel cycle can achieve 1%, slightly better than that of the CANDU reactor at the same physical size and power level. Meanwhile, around 2662 kg U-233, which can start 3 new Th–U fuel cycle HWMSR cores, can be produced over 20 years’ operation by online refueling thorium and extracting Pa-233.