Simulation of MCCI with top flooding with the TOLBIAC-ICB code - 15516

Past experimental programs (MACE, CCI-OECD) have brought out some phenomena that could increase heat transfer between corium and water and thus slow down the interaction and, in some cases, stop it. The most efficient phenomena which have been identified are the melt ejection of corium which can lead to the formation of a coolable debris bed and the water-ingression that can significantly thicken the crust that forms at the top surface of the corium pool. The TOLBIAC-ICB code has been developed to simulate molten core concrete interaction (MCCI). The general approach used in this code is based on the segregation phase model which assumes that a crust mainly composed of refractory oxides forms at the pool boundaries. The interfacial temperature between the crust and the pool is the liquidus temperature calculated with the composition of the pool. Models have also been implemented to deal with MCCI under water and more particularly to take into account the melt ejection phenomenon. Some validation calculations related to MCCI with top flooding have been presented in this paper. The results obtained for two different kinds of concrete, M3b for LCS concrete and CCI6 for siliceous concrete provide a set of consistent results which are close to the data obtained in the experiments