Numerical analysis of simulant effect on natural convection characteristics in corium pools

In-vessel retention (IVR) is considered as an effective mitigation strategy in realms of nuclear safety. Extensive experimental investigations have been done on the natural convection characteristics of corium pools according to the IVR concept, using various simulant materials. Based on the known COPRA (Corium Pool Research Apparatus) molten salt experiments, in which the eutectic salt (50 mol% NaNO₃-50 mol% KNO₃) and the non-eutectic salt (20 mol% NaNO₃-80 mol% KNO₃) were used as simulant materials, this paper evaluates extensively the simulant effect of simulant material on natural convection behaviors inside the corium pools through numerical simulation. The Wall-Modeled LES (WMLES) method was employed for the turbulence calculation. The distributions of corium pool temperature and heat flux as well as the crust thickness from the numerical simulations were validated with experimental data. Through numerical simulations, this work provides detailed temperature fields and velocity fields inside a large internally heated corium pool, and further discusses in depth the interplay between the heat transfer characteristics and the natural convection behaviors. This work can provide references for the selection of simulant material in the future experimental research.