Neutronics aspects of the FESS-FNSF

•FNSF design shown to breed sufficient tritium in order to be self sufficient.•Heating, damage and dose to magnet insulator found to meet requirements.•A number of regions beyond the power core were found to have high He/DPA ratios. Neutronics analysis was performed on the latest Fusion Energy System Studies-Fusion Nuclear Science Facility (FESS-FNSF) design, which determined the neutron wall loading, tritium breeding ratio, and radiation damage. Sixteen different sectors configurations were investigated, with the main focus on determining the impact which each has upon the tritium breeding ratio (TBR) of the whole facility. This paper describes the stages of the nuclear analysis that serve to prove the radiation derived attributes of the system.