The phenomenon of cooling of molten core material inside the lower head of a pressurised water reactor pressure vessel has been analysed numerically. A detailed analysis of interaction of surface radiation and conjugate wall conduction with free convection inside the semi-circular cavity has been presented. The effect of parameters which govern the radiative heat transfer from the pool surface has been investigated. The results show that for a certain set of parameters radiative heat transfer from the pool surface is more efficient than convection towards vessel circular wall. For all the cases considered in the present analysis well-stratified corium pool has been obtained. (C) 2001 Elsevier Science Ltd. All rights reserved.