Risk assessment of the early containment overpressurization for HPR1000 nuclear power plant

This paper presents a systematic evaluation of the risk of early containment overpressurization for the HPR1000 nuclear power plant. Probabilistic analysis and nonlinear finite element numerical simulation methods are first applied to establish the containment failure probability curve. On the basis of two representative accident scenarios, namely the Large Break Loss-of-Coolant Accident (LLOCA) and the Main Steam Line Break (MSLB), pressure variations within the containment during the initial stages of the accidents are examined in detail through deterministic analysis methods. The results are subsequently compared with the containment failure probability curve to evaluate the risk of early containment overpressurization. The analysis indicates that within 24 hours, the probability of containment failure corresponding to the peak pressure is negligible. This finding demonstrates that the containment design of HPR1000 exhibits high reliability even under severe accident conditions, and the likelihood of early overpressure failure caused by steam release can be disregarded. The outcomes of this study provide valuable reference for the safe operation of HPR1000 and the safety design of future nuclear power plants.