Molten Salt Reactor Simulation by a MOOSE-Based Application Suanni

Abstract Liquid fueled Molten Salt Reactors use homogeneously mixed fuel and have less heterogeneity than traditional solid fueled reactors. The two-step method successfully applied for Light Water Reactors is expected to obtain good accuracy and efficiency in MSR simulations. This paper implements a two-step procedure into a newly developed code Suanni based on the Multi-physcis Object Oriented Simulation Environment (MOOSE) framework. Suanni utilizes an open-source Monte Carlo code OpenMC for producing few-group cross sections and providing high-fidelity solutions to calculate super homogenization (SPH) factors. A diffusion solver with continuous finite element method is implemented in Suanni for the second step core simulation with SPH corrected cross sections. A Molten Salt Thermal Reactor (MSTR) core is used for the verification of the newly developed code, and the reference results come from continuous-energy OpenMC calculations. The keff and power errors are relatively large when no SPH correction is used. These errors can be significantly reduced with 4-group SPH corrected cross sections, where kes error is less than 300 pcm and relative power errors range from −2.4% to −0.35% for 3D rod-in MSTR simulation.