Development and testing of a coupled SuperMC and SUBCHANFLOW code for LWR simulations

Coupled neutronics and thermal-hydraulics simulations have evolved in the numerical modelling of light water reactors (LWRs) recently. To meet the request of large-scale coupling analyses, this study conducts the steady-state coupling simulations by using the Monte Carlo neutronics code, SuperMC, and the sub-channel code, SUBCHANFLOW. An external coupling mode is adopted in the coupling code, which provides a flexible selection of thermal-hydraulic codes. An on-the-fly Doppler broadening method is used in the coupling code to decrease its complexity. Based on the innovative CAD functions of SuperMC, two different methods are developed to create the data mapping between SuperMC and SUBCHANFLOW. To accelerate the convergence speed, the stochastic approximation method is applied to the coupling iterations. The coupling code is tested with a PWR single pin case, a BWR 3 × 3 cluster case, and a PWR full-assembly case. The results show a good agreement with the reference results calculated by other similar coupling codes. In conclusion, this study demonstrates the ability of SuperMC to perform large-scale steady-state coupled neutronics and thermal-hydraulics simulations of LWRs.