Analysis on Thermal Load Response of the In-Vessel Retention During a Severe Accident

Abstract

A thermal load from the molten pool in the lower plenum to the reactor vessel during a severe accident has been analyzed. The configuration of the molten pool was considered as a two-layer. A heat flux distribution, crust thickness and vessel thickness were mainly investigated in this study. Non-linear Newton-Raphson iteration method was easily applied to solve a set of governing equations. Of many severe accident sequences, SBLOCA (Small Break Loss-Of-Coolant Accident) and LBLOCA (Large Break Loss-Of-Coolant Accident) without SI (Safety Injection) in the APR1400 were considered. From the results, the focusing effect in light metallic layer could be seen and other important parameter was also explained.