In this study, COMSOL v5.2 Multiphysics software was utilized to perform coupled neutronics and thermal-hydraulics simulations of a molten salt fast reac-tor, and the SCALE v6.1 code package was utilized to generate the homogenized cross-section data library. The library’s 238 cross-section groups were categorized into nine groups for the simulations in this study. The results of the COMSOL model under no fuel flow conditions were verified using the SCALE v6.1 code results, and the results of the neutronics and thermal-hydraulics simulations were compared to the results of previously published studies. The results indicated that the COMSOL model that includes the cross-section library generated by the SCALE v6.1 code package is suitable for the steady-state analysis and design assessment of molten salt fast reactors. Subse-quently, this model was utilized to investigate the neu-tronics and thermal-hydraulics behaviors of the reactor. Multiple designs were simulated and analyzed in this model, and the results indicated that even if the wall of the core is curved, hot spots occur in the upper and lower portions of the core’s center near the reflectors. A new design was proposed that utilizes a flow rate distribution system, and the simulation results of this design showed that the maximum temperature in the core was approxi-mately 1032 K and no hot spots occurred.