Neutronics/Thermal-Hydraulics Coupling Simulation Using JAMPAN in a Single BWR Fuel Assembly

Abstract We have aimed to realize high-fidelity neutronics/thermal-hydraulics coupling simulation to provide simulation results that can be used as validation data for reactor analysis codes. We have developed a multi-physics platform, JAMPAN, to conduct neutronics/thermal-hydraulics coupling simulation by connecting independent codes. It is required to reduce empirical correlations as far as possible to perform high-fidelity neutronics/thermal-hydraulics coupling simulation. Hence, a continuous energy Monte Carlo code MVP is adopted as a neutronic analysis code, and a detailed and phenomenological numerical simulation code JUPITER is adopted as a thermal-hydraulics analysis code. Our simulation target is a single BWR fuel assembly. Hence, the simulation results need to reproduce the varying heat generation owing to the varying void fraction. Therefore, we carried out MVP/JUPITER coupling simulation in a 8 × 8 single fuel assembly of BWR and confirmed that the void fraction and heat generation distribution are reasonable qualitatively. Furthermore, it is required to clarify the effect of the parameters of the coupling simulation on the results, and the time interval is one of the coupling parameters to improve the reliability of the simulations. We carried out MVP/JUPITER coupling simulation in a 2 × 2 fuel pin system using the multi-physics platform JAMPAN to investigate the effect of the time interval on the results. A 2 × 2 fuel pin system, which is the smaller unit of the actual single fuel assembly for a BWR, is adopted as a simulation target to effectively investigate the effect. It is found that the effect of the time interval on the simulation results is small.