Numerical studies on penetration integrity of the KNGR lower pressure vessel in a severe accident

Numerical studies are conducted in parallel to experiments on penetration integrity of a lower pressure vessel in the Korean Next Generation Reactor(KNGR). KNGR-ICI-DRY experiments were performed two times without external vessel cooling. In this study experimental results on KNGR-ICI-DRY2 case was evaluated numerically using commercial software FLUENT and in-house code LILAC which has been developed at KAERI for a multi-dimensional analysis of melt pool in a pressure vessel. Natural convection and solidification of alumina melt are modeled in the numerical study. And conjugate heat transfer between the alumina melt and vessel are solved from the numerical results it is found that ICI nozzle directly contacted with alimina was melted and this melting heat affected heat transfer to lower vessel wall. The numerical and experimental analysis depict that the thermal load from 40 kg of alumina used in the KNGR-ICI-DRY2 case is not enough for failure of penetration integrity