An investigation of the effects of neutron energy-group structures and resonance treatment in a fusion-fission hybrid reactor fuelling with Tho2

The study has shown that neutron reactions above a threshold energy in fast neutron groups are less sensitive to resonance treatment, such as 7Li(n,αn′)T and 232Th(n,f). Neutron energy-group structures in the neutron libraries and description of fusion neutron source spectrum mainly affect these reactions. On the other hand, neutron reactions in the resonance and thermal energy groups are sensitive to resonance treatment, such as 6Li(n,α)T and 232Th(n,γ), depending on the resonance structures. In the fast blanket calculations, resonance-based errors are lower and neutron source based errors are higher than in the moderated blanket. Furthermore, a correct description of the fusion neutron source spectrum over several neutron energy groups is essential to calculate fission reaction rates, fission heating density, fusile and fissile breeding rates and neutron leakage accurately.