## 6 Conclusions  
Liner corrosion represents a primary form of aging-related degradation in the NCS. Evaluating the corrosion effects of the liner is essential to guaranteeing the safe operation of the NCS. In this paper, the corrosion mechanism of the containment liner is elucidated. Combined with the sub-modeling technique, a refined simulation method is proposed to investigate the localized corrosion effects of the liner on the leak-tight function of the NCS under LOCA conditions. Utilizing a probabilistic FE method, the fragility and leakage risk of the NCS under different degrees of liner corrosion are evaluated in detail. The main conclusions can be drawn as follows:  
1. The fragility curve of the NCS under LOCA conditions gradually moves to the left as the corrosion degree of the liner increases, which indicates that the risk of containment leakage increases under the same internal pressure. 2. The NCS under liner corrosion conditions is susceptible to functional failure at lower levels of accident pressure. Compared to the uncorroded case, the median pressure capacity of the NCS with 10%, 20%, and 30% corrosion degrees is reduced by 6.26%, 11.72%, and 16.02%, respectively. 3. The HCLPF capacity reflects the most conservative pressure capacity of the NCS. Compared with the uncorroded case, the HCLPF capacity of the NCS with 10%, 20%, and 30% corrosion degrees of the liner is reduced by 6.79%, 12.83%, and 17.35%, respectively, which is slightly higher than the reduction rates calculated based on the median pressure capacity. 4. The probabilistic safety margin gradually decreases as the corrosion degree and confidence level increase. When the corrosion degree reaches 30%, the probabilistic safety margin with a 95% confidence level drops to 2.7. 5. Liner corrosion can significantly increase the total probability of failure of the NCS under LOCA conditions. Within the scope of this paper, the investigated NCS can fulfill the probabilistic safety requirements. Conceptualization, X.L. ; Methodology, X.L. ; Software, X.L. ; Validation, X.L. ; Formal analysis, X.L. ; Investigation, X.L. ; Resources, J.G. ; Data curation, X.L. ; Writing--original draft, X.L. ; Writing--review and editing, J.G. ; Supervision, J.G. ; Project administration, J.G. ; Funding acquisition, J.G. All authors have read and agreed to the published version of the manuscript. This work was supported by the National Key R&D Program of China (Grant No. 2019 YFB1900903) and the National Natural Science Foundation of China (Grant No. U22B20125). These supports are sincerely acknowledged. Not applicable. All data supporting the findings of this study are available from the corresponding author upon reasonable request, but all personally identifiable information will be identified before transferal. The authors declare no conflicts of interest. \begin{table}
\begin{tabular}{c c c c c} \hline \(\eta\) & 0\% & 10\% & 20\% & 30\% \\ \hline \(P_{\text{fail}}\) & 0.0024 & 0.0044 & 0.0075 & 0.0114 \\ \hline \end{tabular}
\end{table} 
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