Comparison analysis of 1D/2D/3D neutronics modeling for a fusion reactor

Fusion reactors have the characteristics of a strong anisotropic neutron flux distribution, wide range of neutron energy and spatial non-uniformity of the power density distribution caused by the external fusion neutron source. The static state neutronics analyses of a fusion power reactor (named FDS-II) have been carried out to find out the effects of the 1D/2D/3D geometric descriptions for computational models. The neutron wall loading distribution, tritium-breeding ratio and power density distribution are calculated to evaluate the nuclear performance using the Monte Carlo transport code MCNP4C and nuclear data library FENDL-2.1. Comparison of the results suggests that the value of TBR calculated by the 1D approach overestimates the tritium-breeding ratio especially in the inner blanket. The power density distribution based on the 2D and 3D models were similar since they all consider the effects of the axial components. For obtaining global scalar quantities for general use, simplified models of the fusion reactor are usually sufficient. However, more calculations are needed to test the validity of each model in different regions of phase space.