Model Development Of AP1000 Npp SB-LOCA And Associated Application With Realp5

AP1000 Nucleae Power Plant is the third generation nuclear power plant of the world that our country has introduced from Westinghouse of United States which designed the AP1000. AP1000 has one reactor vessel and two loops,and it's rated thermal power is 3400MWt. AP1000 is different from the conventional PWRs; the biggest difference between AP1000 and the conventional PWRs is that AP1000 has the passive reactor core cooling system. As compared to the conventional PWRs, IRWST will replace the low pressure safety injection system, and IRWST will provide the safety injection mass flow for the long term cooling; CMT will replace the high pressure safety injection system, and CMT will provide the large mass flow at the early time of the accident. ACC will inject cooling water at middle pressure after the accident happens. AP1000 has designed the ADS system and the PRHR system creatively. When the SB-LOCA happens, with the system pressure decreasing because of blowdown from the break and ADS valve, the coolant will be injected to the RPV from the CMT and ACC. When the system pressure decreases to the pressure value of the IRWST injecting, the water in the IRWST will inject to the RPV because of the gravity of the water. So the reactor core will stay at the long term cooling state.First of all, this paper develops the AP1000 RELAP5 SB-LOCA model using the conservative parameters, and we evaluate our REALP5 model by comparing with Westinghouse SB-LOCA analysis with NOTRUMP code model.Secondly, we has studied the special design fearture of AP1000 using the RELAP5 SB-LOCA model, including the case that the SB-LOCA coupled with the failure of ADS and the case that the SB-LOCA coupled with the failure of the CMT.Finally, this paper has studied the effect of the break positon and the Reactor Coolant Pump operating state on the SB-LOCA, also has studied the case that the double ended of the direct vessel injection line coupled with the failure of the ADS. Besides,we has studied the effect of the power uprate on the PCT of SB-LOCA,and the effect of the break area on the PCT of SB-LOCA. And finally we have studied the effect of some significant thermal hydraulic models including CCFL model and Critical Flow model on SB-LOCA calculation.