Neutronics analysis of the power flattening and minor actinides burning in a thorium-based fusion–fission hybrid reactor blanket

Abstract A neutronics analysis has been performed for a thorium fusion breeder with a special task of burning minor actinide 237 Np, 241 Am, 243 Am, and 244 Cm, and production of 233 U for the future PWR application. Under a first wall fusion neutron wall loading of 0.1 MW/m 2 by a plant factor of 100%, preliminary neutronics calculations have been performed using the one-dimensional transport and burnup calculation code BISONC and the Monte Carlo transport code MCNP. To obtain a quasi-constant nuclear heat production density, 11 fuel rods containing the mixture of ThO 2 and minor actinides are placed in a radial direction in the fissile zone where ThO 2 is mixed with variable amounts of minor actinides. Calculation results show that the tritium breeding ratio is greater than 1.05 for both investigated Cases A and B, and the hybrid reactor is self-sufficient in the tritium required for the (DT) fusion driver in those models during the operation period. The blanket energy multiplication factor M , varies between 13.8 and 29.6 depending on the fuel types at the end of the operation period. The peak-to-average fission power density ratio ( Γ ) is less than 1.66 and 1.68 for both Cases A and B, respectively during the operation time. After 720 days of plant operation, the accumulated 233 U is 1277 and 1725 kg in the blanket for the Cases A and B, respectively.