Analysis of Th-U breeding capability for an accelerator-driven subcritical molten salt reactor

Accelerator-driven systems based on molten salt fuel have several unique advantages and features for advanced nuclear fuel utilization. The aim of this work was to study the Th-U breeding capability in such systems, known as "accelerator-driven subcritical molten salt reactors" (ADS–MSRs). Breeding capacities including conversion ratio and net ${}^{233}\text{U}$ production for various subcriticalities and different minor actinides (MA) loadings were analyzed for an ADS–MSR. The results show that the subcriticality of the core has a considerable effect on the Th-U breeding. A high subcriticality is favorable to improving the conversion ratio, increasing the net ${}^{233}\text{U}$ production, and reducing the doubling time. Specifically, the doubling time for $k_{eff}$ of 0.99 is larger than 80 years, while the counterpart for $k_{eff}$ of 0.93 is only approximately 22 years. Nevertheless, in an ADS–MSR with a high initial MA loading, MA results in a non-negligible ${}^{233}\text{U}$ depletion in the first two decades, while increasing the net ${}^{233}\text{U}$ production compared to reactors without MA loading. During the 50 years of operation, for the subcritical reactor ($k_{eff}=0.97$) with MA fraction increasing from 1 to 14% , the net ${}^{233}\text{U}$ production increases from 3.94 to 8.24 t.