Large eddy simulation for the thermal behavior of one-layer and two-layer corium pool configurations in HPR1000 reactor

The Large Eddy Simulation (LES) methods were employed to analyze the turbulent heat transfer characteristics in detail for volumetrically heated corium pools. The main components and property parameters were calculated for the one-layer and two-layer configurations in the HPR1000 reactor. The numerical simulations were performed based on the WMLES turbulence model, phase change model, as well as the VOF model to describe thermal behaviors in the corium pool such as natural convection flow, pool temperature field and heat flux distribution. Then based on the Kelvin-Helmholtz (KH) instability theory, the calculated velocity vector difference between the two-layer flows at the interface was lower than the KH instability critical value. The high Rayleigh number natural convection in the bottom oxide pool was still not able to entrain the top metal layer. The molten salt (20 mol% NaNO3-80 mol% KNO3) and the Lead-Bismuth eutectic (44.5 wt% Pb-55.5 wt% Bi) were chosen as the appropriate simulant materials for the two-layer corium pool. The simulation results presented similar thermal characteristics compared with those from the prototypical reactor two-layer case, which could provide guidance for further research.