Containment integrity analysis under accidents

Containment integrity analyses for current nuclear power plants(NPPs) mainly focus on the internal pressure caused by design basis accidents(DBAs).In addition to the analyses of containment pressure response caused by DBAs,the behavior of containment during severe accidents(SAs) are also evaluated for AP1000 NPP.Since the conservatism remains in the assumptions,boundary conditions and codes,margin of the results of containment integrity analyses may be overestimated.Along with the improvements of the knowledge to the phenomena and process of relevant accidents,the margin overrated can be appropriately reduced by using the best estimate codes combined with the uncertainty methods,which could be beneficial to the containment design and construction of large passive plants(LPP) in China.