Neutronics Design of Molten Salt Reactor for Transmutation of Various Radioactive Nuclides

Abstract The graphite-moderated fluoride molten salt reactor for simultaneous transmutation of MA (minor actinides) and FP (fission products) is proposed in the present study. In this core concept, MA is transmuted in the core region by mixing MA nuclides into the fuel salt; FP is transmuted in the reflector region surrounding the core by introducing the FP-containing molten salt different from the fuel salt. Two types of MA-loading fluoride fuels are considered: the uranium fuel with TRU nuclides (U+TRU fuel) and with MA nuclides (U+MA fuel) from PWR spent nuclear fuel. The FP nuclides considered in this study are the soluble LLFP nuclides: Se-79, Zr-93, Sn-126, I-129, and Cs-135, and the dominant heat generation nuclides: Sr-90 and Cs-137. The criticality and burnup calculations are performed using Serpent2, and the feasibility of simultaneous transmutation of MAs and FPs is investigated. The burnup analyses show that the transmutation amounts of Se-79, Sr-90, I-129, and Cs-137 in the FP salt are larger than the production amount in the fuel salt. The amount of MA transmutation in total for U+MA fuel is larger than that for U+TRU fuel and exceeds the MA production amount in a typical LWR.