Calculation of Heat Fluxes Exiting a CANDU Calandria During In-Vessel Retention

Finite element analysis is used to study heat transfer from a corium pool at the bottom of the calandria to its surroundings during a severe accident in a CANDU 6 reactor. The shape of the corium crust around the pool and the steady-state heat fluxes exiting the calandria are calculated for representative accident conditions. The sensitivity of the results to several model parameters is examined. Calculated heat fluxes can be compared to measurements of the critical heat flux at different locations on the outside of the calandria in order to assess the possibility of in-vessel retention of the molten core.