A comparative neutronic analysis of U–Th fuels as potential alternatives to traditional UO2 fuel for enhanced performance and safety in the ACP-100 SMR

Abstract

This study examines U–Th-based alternative fuel options for the ACP-100 reactor core through a neutronic lens. Neutronic simulations were performed utilizing the Monte Carlo SERPENT code for 540 EFPDs. This study seeks to overcome the limitations of traditional UO₂ fuel by exploring alternatives that provide enhanced performance, greater resource availability, and increased safety. This study evaluates U–Th-based carbide, nitride, and oxide fuels in comparison to conventional UO₂. Among the alternatives, U–Th-based fuels exhibit a 40 % higher conversion ratio compared to UO2, along with superior neutron flux and enhanced transmutation capabilities with isotopes relative to other evaluated fuel elements. A suppressed trend is noted in keff and burnup for U–Th-based fuels in comparison to UO₂. Nonetheless, U–Th fuels demonstrate favorable outcomes regarding safety parameters, including ppfs, MTC, FTC, and βeff. The U–Th-based fuel elements with added nitride and carbide exhibit reductions in ppfs of 1.78 % and 1.5 %, respectively, when compared to UO2. The findings offer important insights into the neutronic behavior of U–Th-based fuels and their potential to enhance the performance and safety of the ACP-100 reactor.