Transmutation of americium and neptunium in the single-fluid double-zone thorium-based molten salt reactor

In the current work, we introduce a new approach compared to solid-fuel reactors to load the minor actinides (MAs) into the Single-fluid Double-zone Thorium-based Molten Salt Reactor (SD-TMSR). The proposed approach merges the advantages of both homogeneous and heterogeneous approaches. Among MAs nuclides, Am-241 and Np-237 are selected for transmutation due to their long half-life. We simulate two separate tanks; Pu + U tank and FPs tank. In this study, a tank is a right cylinder with a volume of 1.0 m(3). The Pu + U tank is used to store Pu and U isotopes extracted from the central channel of the SD-TM SR. However, the FPs tank is used to store all fission products (FPs) produced from the transmutation process in the central channel. The overall change in the actinides and FPs mass during the irradiation has been calculated using direct SERPENT-2 calculations. The results show that the transmutation ratio of Am-241 and Np-237 reaches 98.5% and 93.2%, respectively after 1500 days of irradiation. We notice that the major isotope in the Pu + U tank is Pu-238. Under Am-241 irradiation, our proposed approach offers approximate to 0.3 kg of Pu-238 after 1 year of operation. However, under Np-237 irradiation, 2.5 times more Pu-238 can be extracted after the same period of operation. The produced Pu-238 can be used in the radioisotope thermoelectric generators (RTG, RITEG) and radioisotope heater units.