Preliminary Neutronic Analysis of Th-TRU Annular Fuel in Pressurized Water Reactors

To address uranium resource conservation and the reduction of high-level radioactive waste inventory for sustainable nuclear energy development, the utilization of thorium-based fuels for high-level radioactive waste transmutation has become a major global research focus. This work, based on China's fully indigenous HPR1000 reactor core design and leveraging annular fuel characteristics, employs Monte Carlo methods to investigate and analyze the neutronic performance—including physical properties, breeding performance, and safety parameters—of Th-TRU fuels. A comparative analysis with conventional UO₂, (Th,²³³U)O₂, and (Th,U)O₂ fuels was conducted. Key findings reveal that all three thorium-based fuels—(Th,²³³U)O₂, (Th,U)O₂, and Th-TRU—exhibit superior neutronic performance compared to UO₂, with Th-TRU fuels demonstrating the most significant enhancements. Th-TRU fuels substantially improve core neutronic performance and effectively transmute minor actinide (MA) nuclides, with (Th,²³³U, 4wt% TRU)O₂ demonstrating the most effective transmutation capability. Furthermore, Th-TRU fuels maintain both fuel temperature coefficient (FTC) and moderator temperature coefficient (MTC) within wide safety margins and effectively reduce the power peaking factor, highlighting their potential as candidate fuels for pressurized water reactors (PWRs). This study provides insights into the utilization of thorium-based fuels for transmuting TRU in PWRs.