Verification and Geometry Optimization of a One Fluid Molten Salt Reactor (OFMSR) with Fixed Volume

Thermal molten salt reactors can be designed in many configurations. This paper investigates the optimal geometry of a one fluid molten salt reactor (OFMSR) in a virtual one-and-half fluid configuration with a fixed fuel salt volume. Two primary configurations were studied, axial blanket (three models) and radial blanket (two models). Neutronic calculations were performed using MCNP6.2 and Serpent-2 reactor physics codes with ENDF/B-VII.0 continuous neutron library. The analysis comprises criticality calculation, temperature coefficient of reactivity (TCR), breeding ratio (BR), and kinetic parameters. The results imply a good agreement between MCNP and Serpent calculations. TCR values show a different pattern between axial and radial blanket configuration. Whilst the correlation between TCR and BR is inversely correlated in axial blanket, it is linear in radial blanket configuration. Overall, radial blanket configuration seemed to show better neutronic performance than axial blanket configuration, with comparably strong negative TCR and large BR.