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

A neutronics analysis has been performed for a thorium fusion breeder with a special task of burning minor actinide 237Np, 241Am, 243Am, and 244Cm, and production of 233U for the future PWR application. Under a first wall fusion neutron wall loading of 0.1 MW/m2 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 ThO2 and minor actinides are placed in a radial direction in the fissile zone where ThO2 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 233U is 1277 and 1725 kg in the blanket for the Cases A and B, respectively.

► Neutronics analysis of the power flattening and minor actinides burning in a thorium-based fusion–fission hybrid reactor blanket. ► The blanket is self-sustaining with TBR > 1.05. ► The peak-to-average fission power density ratio is less than 1.66 and 1.68 for both Cases A and B. ► The blanket energy multiplication factor M varies between 13.8 and 29.6.