Thorium-fueled molten salt reactors (TMSRs) offer notable advantages over conventional reactor systems, including improved waste management, reduced system complexity, and lower cost. This study investigates the neutronics performance of various TMSR configurations by evaluating how different fluoride-based molten salt compositions affect reactor criticality and neutron characteristics.

Ten fluoride-based molten salts were analyzed under diverse geometric and moderation conditions, utilizing a fixed cylindrical core design with both hexagonal and square lattice arrangements, and moderated by graphite or BeO. The salt mixtures tested contained a constant heavy metal fraction comprised of 12 mol % 232Th and 0.3 mol % 233U, supplemented by various nonfissile nuclides. Neutronic simulations were performed using the MCNP6.2 radiation transport code at beginning-of-cycle conditions for a thermal power level of 2000 MW(thermal).

The FLiBe salt demonstrated particularly favorable results, with a neutron flux profile supporting both fuel consumption and breeding. This research identifies critical reactor configurations suitable for sustained operation and provides a comparative assessment of salt, moderator, and lattice combinations relevant to future TMSR designs.