An Evaluation of a Coolant Injection into an In-Vessel with a RCS Depressurization during a SBLOCA in OPR1000

Coolant injection into an in-vessel with a RCS (reactor coolant system) depressurization is a very important strategy to prevent a reactor vessel failure during a severe accident. This can be achieved by the operation of the safety injection system with a RCS depressurization by using the safety depressurization system (SDS) and the steam generator. The positive effects of this strategy are to cool down the core, to prevent a reactor vessel failure, and so on. The negative effect of this strategy is an enhanced hydrogen generation and so on. For this reason, this strategy of a severe accident management should be evaluated in detail. A coolant injection into an in-vessel with a RCS depressurization to prevent a reactor vessel failure in OPR (Optimized Pressure Reactor) 1000 has been evaluated by using the SCDAP/RELAP5 computer code1. In this study, a small break loss of coolant accident (SBLOCA) was selected as an initial event, because this is a dominant severe accident sequence in the OPR1000. The safety injection into the in-vessel with a RCS depressurization by using the steam generators has been evaluated for a SBLOCA. Sensitivity studies on coolant injection timing and its capacity have been performed to determine the proper operation time