Seismic Fragility Analysis of Containment Structures in Nuclear Power Plants Considering Alkali‐Silica Reaction

ABSTRACT This study quantifies the influence of alkali‐silica reaction (ASR) on the seismic fragility of prestressed concrete containment structures in nuclear power plants (NPPs). Global collapse was considered as the governing failure mode to maintain consistency with current risk assessment frameworks, and was captured using a finite element model constructed with multi‐layered shell elements implemented in OpenSees. ASR effects were implemented using a thermo‐mechanical, time‐dependent material model and validated against experimental results from concrete prism and reinforced concrete shear wall specimens affected by ASR. Fragility analyses were then conducted using two stripe‐based approaches: lognormal fitting (Method A) and maximum likelihood estimation (MLE). As an exploratory case, ASR progression was assumed to be concentrated in the bottom region of the containment structure. For the case‐study containment structures, reductions in median capacity and HCLPF due to ASR were found to be in the ranges of 1.843%–3.556% and 3.962%–4.133%, respectively. Method A provided better estimates of failure at lower PGA levels, while MLE performed better at higher PGA levels.