Integration of minor actinide coatings into (Th, 233 U)O 2 fuel: A strategy for excess reactivity mitigation and radioactivity management

This study investigates the application of minor actinides (MAs) as a cladding layer on thorium–uranium fuel to simultaneously mitigate excess reactivity at the beginning of the fuel cycle (BOC) and provide an effective pathway for MA transmutation. Four different MA loadings, represented by distinct cladding thicknesses, were applied to (Th, 233 U)O 2 fuel pellets and benchmarked against both conventional UO 2 and uncoated (Th, 233 U)O 2 fuels. Neutronic analyses were performed to evaluate burnup evolution, safety-related parameters, MA depletion, radioactivity buildup, and the spatial distributions of neutron flux and power. The results demonstrate that the incorporation of MAs into the cladding suppresses excess reactivity at BOC while enhancing fuel performance relative to UO 2 and uncoated thorium–uranium fuel. In addition, the approach reduces the accumulation of proliferation-sensitive isotopes such as 237 Np, 241 Am, and 244 Cm in spent fuel, while enabling efficient MA transmutation. Overall, the proposed concept provides a dual benefit of improved reactivity management and long-term reduction of radiotoxicity in the nuclear fuel cycle.