The analysis of the migration of source term under severe accident is one of the important aspects of‘Studies on Migration Mechanism of the Source Term under Severe Accident’,which is a significant task of the National Large Advanced PWR Research Program.This research aims at building up a method for analyzing fission product behavior in the containment with CFD code.The effect of PCCS(Passive The analysis of the migration of source term under severe accident is one of the important aspects of ’Groups on Migration Mechanism of the Source Term under Severe Accident’, which is a significant task of the National Large Advanced PWR Research Program. This research aims at building up a method for analyzing fission product behavior in the containment with CFD code.The effect of PCCS (Passive