Simulation Research on Containment Response under Severe Accident Condition

During the severe accident of pressurized water reactor, steam and hydrogen released from primary system, and core melt released to the containment after reactor pressure vessel (RPV) fails, all pose a threat to the integrity of the containment. The containment response of the domestic second generation pressurized water reactor was analyzed using MAAP code in the paper. Two severe accident conditions were selected. The first is hot leg middle break loss of coolant accident (LOCA) with the equipment cooling system (RRI) failure and the recirculating high pressure injection failure. The failure of recirculating high pressure injection leads to the insufficient cooling of core and the melting of core material. After RPV fails, the core melt falls into the cavity, and molten core concrete interaction occurs. Continuous gas release leads to the containment overpressure failure. The second is cold leg large break LOCA with the recirculation failure. The accumulation of steam leads to containment overpressure failure. Through the analysis of the two accident conditions, importances of high pressure injection and containment spray system are confirmed in ensuring the integrity of containment.