The accumulator effects on in-vessel severe accident progression of a three loop PWR nuclear power plant in a SBLOCA without safety injection system

In this paper, the melt core concrete interaction is analyzed using CONTAIN2.0 code for the 4-in. break size without ACCs case as the most serious cases for the time of lower plenum failure. The result for 52.8 h is reported. The in-vessel molten material retention strategy for this case is studied using RELAP5/SCDAP code. The results show that lower plenum integrity is preserved during the severe accident that causes reactor core melt.