Study on containment pressure response with passive containment cooling system performance under design basis accident

The passive containment cooling system which utilizes natural phenomena to remove the energy released from reactor will prevent steel containment from overpressure during the postulated accident and provide long-term cooling to decrease the pressure and temperature of containment. The peak pressure in containment under the design basis accidents is important to the design and evaluation on the passive containment cooling system. In this paper, a dedicated code PCCSAP-3D for the evaluation on the performance of the passive containment cooling system is used to analyze the thermal-hydraulic transients in the containment of the advanced pressurized water reactor AP1000. Some factors are compared to study their e on the peak pressure of containment under the typical loss-of-coolant and main steam-line break accident. The results show that the amount of released coolant, the free volume and shell thickness of containment are dominant for containment pressure during the postulated accident, in comparison with the initial conditions. And the containment pressure response is more sensitive to internal initial conditions than to ambient conditions. The peak pressure under the postulated accidents is mainly contributed from rapid coolant release and it is not sensitive to the containment cooling performed by the passive containment cooling system.