ABSTRACT

The occurrence of common cause failures poses a critical threat to the seismic safety of nuclear power plants. The installation of diverse components such as isolation systems is believed to be a promising strategy to avoid such failures, especially in the context of disasters such as the Fukushima accident. Although the effectiveness of implementing diverse components in enhancing the seismic safety has been qualitatively evaluated, a quantitative examination considering the system reliability has not been performed yet. Therefore, in this study, a method to quantitatively evaluate the effectiveness of diverse components in preventing failures was developed. The definitions of the seismic diversity and robustness in different domains were examined. Subsequently, the proposed approach was used to evaluate the effectiveness of the seismic diversity strategy on enhancing the system reliability at 11 sites in Japan. Moreover, the seismic robustness of the system was assessed. The results indicated that the optimal constitution of diverse components depends on the seismic environment at each site, and the seismic diversity is a more effective strategy compared to that of multiplicity to ensure the seismic safety of nuclear power plants.

摘要

共因故障的发生对核电厂的抗震安全构成了严重威胁。安装隔离系统等多种组件被认为是避免此类故障的一种很有前景的策略，尤其是在福岛事故等灾难的背景下。尽管已对实施不同组件在提高地震安全性方面的有效性进行了定性评估，但尚未进行考虑系统可靠性的定量检查。因此，在本研究中，开发了一种定量评估不同组件在预防故障方面的有效性的方法。检查了不同领域中地震多样性和稳健性的定义。随后，建议的方法用于评估地震多样性战略在提高日本 11 个站点的系统可靠性方面的有效性。此外，还评估了系统的抗震稳健性。结果表明，不同构件的最优构成取决于各场址的地震环境，地震分集是保证核电站抗震安全的一种较多重性更有效的策略。