LAUSR

Abstract To study the hydrogen risk at severe accident of LB-LOCA of cold leg in 1# SG compartment with gravity injection failure and hydrogen igniters without power in AP1000 NPP, we investigate the effect of total amount of inert gas on reducing hydrogen risk during AP1000 post-inerting. The total amount of inert gas is 42 tons, 56 tons and 70 tons respectively. We analyze the average volume fraction of hydrogen, flame acceleration factor and deflagration to detonation transition factor in 1# SG compartment and in the upper space of containment, and the pressure in containment. The results show that, post-inerting can reduce hydrogen risk in containment at severe accident, the more the total amount of inert gas is injected, the lower the possibility of FA and DDT is. Moreover, we must ensure that containment filtration and discharge system is functioning normally at accident conditions to prevent containment from overpressure.