Experimental Study on PORV Stuck-Open Accident in INER Integral System Test Facility

Four scaled small break loss-of-coolant accident (LOCA) tests simulating the pressurizer power-operated relief valve (PORV) stuck-open accidents and the recovery actions in a pressurized water reactor (PWR) were performed at the INER Integral System Test (IIST) facility. The objectives of this study are to verify the effectiveness of emergency operating procedure and emergency core cooling system on reactor safety. The break sizes were volumetrically scaled down based on one and all three fully-opened PORVs which is equivalent to 0.46% and 1.37% cold leg flow area. The experimental results indicate that in case of high pressure injection (HPI) system failure, the rapid depressurization of the steam generators is proved to be an effective way in the depressurization of the reactor coolant system and the core cooling. If the high pressure safety injection operates normally, the core cooling can be adequately provided without operating the secondary bleeding during PORV stuck-open transient.