Analysis of CPR1000 Severe Accident Induced by SBO With SG Safety Valve Stuck Open

The CPR1000 severe accident caused by station blackout (SBO) with the SG safety valve stuck open was modeled and analyzed using MELCOR code, and the simulation of CPR1000 severe accident process was preliminarily achieved. Three assumptions, namely without shaft sealing leakage and auxiliary feed water, with shaft sealing leakage and auxiliary feed water, and with shaft sealing leakage but without auxiliary feed water, were analyzed. The results imply that SG safety valve stuck open has great influence on the accident sequences. According to the calculation results, without shaft sealing leakage and auxiliary feed water, pressure vessel will fail at 9 576 s. When auxiliary feed water supplies, pressure vessel failure delays nearly 30 000 s. When the leakage of the shaft sealing system exists, pressure vessel failure will delay about 50 s. The results show that the auxiliary feed water and the leakage of the shaft sealing system have great mitigation effect on the severe accident induced by SBO with SG safety valve stuck open.