Abstract Nuclear containment structure plays a critical role of providing the leak proof boundary for preventing radioactive material leak into the environment during severe accident conditions. There is a growing demand to quantify the failure probability of containment structure under severe accident conditions. This paper mainly focuses on fragility analysis and performance evaluation of containment structure under severe accident conditions from an innovative perspective. An innovative log-expansion method is proposed based on reliability theory. The obvious advantage of the proposed method is that the computational work is greatly reduced without sacrificing accuracy. The validity of the proposed methodology is verified through cylinder structure subjected to hydrostatic pressure condition and containment structure subjected to overpressure condition, and the proposed methodology is compared with the more accurate but computationally demanding conventional Monte-Carlo sampling technique and Latin hypercube sampling technique. Results indicate that the proposed methodology can provide good estimation of fragility curve of containment structure with less computational work. The 95% non-exceedance pressure capacity of containment structure is 1.29 MPa, which meets the requirement of minimum margin not less than 2.5. Cumulative conditional failure probability (CCFP) of containment structure in this study is 0.0032, which indicates that this containment structure can meet the performance requirements under severe accident conditions.

中文翻译：

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超压条件下安全壳结构的简化易损性分析方法

摘要 核安全壳结构在提供防漏边界以防止严重事故条件下放射性物质泄漏到环境中起着至关重要的作用。人们越来越需要量化严重事故条件下安全壳结构的失效概率。本文主要从创新的角度对严重事故工况下的安全壳结构进行易损性分析和性能评价。提出了一种基于可靠性理论的创新对数扩展方法。所提出方法的明显优点是在不牺牲精度的情况下大大减少了计算工作。通过静水压力条件下的圆柱结构和超压条件下的安全壳结构验证了所提出方法的有效性，并将所提出的方法与更准确但计算量要求更高的传统蒙特卡罗采样技术和拉丁超立方体采样技术进行了比较。结果表明，所提出的方法可以以较少的计算工作提供良好的安全壳结构脆性曲线估计。安全壳结构95%不超压能力为1.29MPa，满足不小于2.5的最小余量要求。本研究中安全壳结构的累积条件失效概率 (CCFP) 为 0.0032，