In-Vessel Retention by External Reactor Vessel Cooling (IVR-ERVC) is one of the severe accident management strategies to terminate or mitigate the severe accident (SA) which is also called ‘core-melt accident’. The reactor vessel which is containing molten core material in the lower head is cooled by flooding coolant. The molten core mixture is expected to be divided into some layers due to the density difference. Fig.2 shows the conventional two layered configuration of IVR. It has light metal layer of Fe-Zr and the ceramic pool of UO2 and ZrO2. The crust would be formed along the oxide layer boundary. The oxide layer contains majority of the nuclides which generates the decay heat. If the generated heat is not removed properly, vessel failure would occur.