Calculation of corium-refractory material interaction with the TIM model

Core-catchers made of ceramic materials have been considered to stabilize corium pool in case of severe acci-dents due to the high melting temperature of ceramics. The design of such mitigating dispositions requires being able to describe the transient corium/ceramic interaction. The Transient Interface Model (TIM) applies to several severe accident situations: in vessel retention as well as corium concrete interaction under transient and steady state regimes. The paper shows that it is also able to handle situations relative to transient refractory material dissolution by a corium melt submitted to residual power dissipation. As long as the pool temperature is below its liquidus temperature, the refractory material is not ablated but could be deposited on the interface provided that the heat flux, which is extracted by conduction through the ceramic layer, is sufficient. When the pool temperature increases above its liquidus temperature, the ceramic wall can be dissolved. The transient evolution of the interface temperature depends on the pool composition and on the ablation rate. The final steady state is reached when the residual thickness of ceramic is compatible with the heat extraction by conduction through the residual wall thickness. The model can be implemented for geometries presenting different heat exchange surfaces.

Automated summary

Core-catchers made of ceramic materials are used to stabilize corium pool in severe accidents. The Transient Interface Model (TIM) can describe the corium/ceramic interaction in different severe accident situations. It can also handle situations where refractory materials dissolve due to residual power dissipation. The model considers factors such as pool composition, ablation rate, and heat extraction for predicting the transient evolution and steady state of the corium/ceramic interface.