The Effect of the SIT Injection Rate on Delaying RPV Failure during Severe Accidents

Studies on reducing such complexity and uncertainty have been conducted recently. A great concern is focused on the core coolability in the case of hypothesized severe accidents. In specific, the relationship between entering severe accident management guidance (SAMG) and accompanying reactor pressure vessel (RPV) failure time was analyzed in our previous study. Lee et al. studied the effect of mitigation strategy of three postulated accidents using the MELCOR code. The objective of this study is to investigate the SAMG entry condition effect on delaying RPV failure. Delayed RPV failure time was measured for postulated scenarios with various SAMG entry conditions. Also mass balance analysis focused on reactor coolant system (RCS) is conducted to investigate safety injection tank (SIT) effect on the RPV failure. Severe accident code MELCOR 1.8.6 was used to simulate and a reference plant is selected as the Korean Pressurized Water Reactor (PWR) Optimized Pressurized Reactor (OPR) 1000. The effectiveness of SAMG entry conditions for the postulated severe accident scenarios was analyzed with the MELCOR 1.8.6. First, SBLOCA, SBO, and TLOFW with mitigation strategies were investigated in terms of delaying RPV failure. The performance of mitigation strategies with four SAMG entry conditions (the time when CET=753, 838, 923 and 973 K) was analyzed