Thorium Utilization Strategy for a Small Modula Molten Salt Reactor

The missions of the Thorium Molten Salt Reactor (TMSR) Nuclear Energy System are to research and develop the thorium based molten salt reactors (MSR) belonging to the fourth generation of nuclear fission reactor system. A Small modular Molten Salt Reactor (SmMSR) is deployed to make full use of the advantages of online refueling and online reprocessing and to consider the rapid deployment of MSR. An innovative "three-stage" strategy of thorium utilization based on SmMSR is proposed to take the current condition of fuel reprocessing and its future evolution. The first stage can realize the thorium utilization at a large scale with online refueling and off-line processing. The second stage can obtain efficient thorium utilization with online refueling, online processing of uranium and off-line processing of minor actinides (MAs). The third stage is implemented with self-sustaining or breeding mode with online refueling and online processing of all heavy metals. Along with the development of three stages, the utilization of heavy metals will be obviously improved and the radio-toxicity will be significantly reduced. A SmMSR is designed to achieve the goals of the first stage of thorium utilization. And three kinds of nuclear fuel cycles with different startup fuel types (i.e., low enriched uranium (LEU), thorium mixed with LEU (LEU+Th) and thorium mixed with ²³³U (²³³U+Th)) are implemented. The results show that the performance for fuel cycle containing LEU is comparable to the pressurized-water reactor (PWR). Meanwhile, the nuclear utilization for that containing ²³³U is much higher than PWR, and the radio-toxicity for which is lower by ~2 magnitudes than that for PWR.