Neutronics evaluation for coating layers of the blanket system in a hybrid fusion-fission reactor

A hybrid fusion-fission reactor (FFH) can be understood as a significant source of fusion neutrons combined with a layer of fissile fuel, which can be used both for the breeding of fissile material and for the transmutation of high-level radioactive waste (HLW), such as the long half-life actinide elements. To evaluate an FFH reactor for the transmutation of reprocessed fuel, two models of an FFH are analyzed: a simpler model for the plasma chamber without the representation of the divertor component (Model 1) and a model with the divertor component represented in a simplified form (Model 2). This work aims to analyze changes in the spectrum of fusion neutrons that reach the transmutation layers (TL) position in the two simulated FFH reactor models, investigating the albedo coefficients calculated through the input and output currents in the beryllium coating layers, heat sink, and tritium production. Differences in the interactions of neutrons with these three layers are observed between the models, initially caused by the scattering of fusion neutrons with the W nuclei of the diverter's plasma facing components (PFC), which can ultimately impact the transmutation rate and energy multiplication between models.