Numerical Simulation of Turbulent Natural Convection within CANDU Corium Under Severe Accidents

Abstract

Turbulent natural convection within the molten corium pool of a CANDU reactor under a severe accident scenario has been modeled using large eddy simulation (LES) in OpenFOAM. The computational model was validated using benchmark experimental results available for turbulent natural convection in heated cavities and the model is being used to simulate the natural convection flow and heat transfer within CANDU corium. The preliminary results for the specific boundary conditions and volumetric heat generation rate indicate that the entire pool will be well-mixed due to turbulent natural convection currents. The study also predicted the heat flux distribution along the vessel wall and showed that the maximum heat flux at the calandria vessel wall will be near the top surface of the pool. The maximum wall heat flux is below the expected critical heat flux on the exterior of the calandria wall.