Revolutionizing LWR SMR reactors: exploring the potential of (Th-233U-235U)O2 fuel through a parametric study

Abstract

ABSTRACT Small modular reactors (SMRs) have garnered significant attention for their operational adaptability and ease of deployment. Thorium, with its well-documented advantages, shows promise as a viable fuel option for SMRs. However, the absence of intrinsic fissile components in thorium necessitates the exploration of different thorium-based fuel combinations. One such combination, (Th-233U)O2 fuel, has limitations due to the presence of pure U-233. To overcome this challenge, a new fuel mixture, (Th-233U-235U)O2, was investigated for SMRs. This study examined the reactor physics characteristics of the (Th-233U-235U)O2 fuel, including fuel burnup, neutron flux spectra, power distribution, the evolution of actinides, and reactivity coefficients. Results indicate that the (Th-233U-235U)O2 fuel allows for a longer criticality period compared to UO2 fuel, with up to a 14% improvement, while accumulating fewer plutonium and transuranic elements. Notably, it demonstrates significantly improved negative reactivity coefficients, particularly for moderator temperature, with an average improvement of 45% over (Th-233U)O2 fuel. The conceptual (Th-233U-235U)O2 fuel, therefore, exhibits promising neutronic properties, presenting possibilities for future studies. These findings contribute to the understanding and advancement of advanced fuel designs for SMRs.