Research of Debris Blocking in PWR Vessel After LOCA

One issue about sump strainer downstream Blocking after LOCA has aroused a widespread concern in nuclear safety authorities and nuclear power plants owners. In this paper, the primary loop and the partial second loop of CPR1000 NPP were modeled for calculation based on the RELAP5 code. Direct injection phases of four typical LOCA cases were simulated, the blocking effect of the limiting LOCA in sump recirculation phase was analyzed by sensitivity studies, then the blocking limit for CPR1000 in-vessel was established. Furthermore, the calculation based on the test had been carried out, and the results show that the requirements of the core cooling have been met in actual blocking situation.