Seismic capacity evaluation of NPP electrical cabinet facility considering grouping effects

This study investigates the fragility assessment of the electrical cabinet facility, a steel structural form that exhibits behavior and response patterns distinct from the normal structure. To evaluate this cause, a set of 40 ground motions was spectrally matched to the design response spectra (RG 1.60) and incremental dynamic analysis was considered. The two design guidelines including earthquake loss estimation methodology (HAZUS) and Nuclear Regulatory Commission (NUREG) were followed. Using the response statistics with the consideration of different damage states, the corresponding fragility curves were developed. For validation, the developed fragility functions were found to be consistent with the fragilities available in the HAZUS and NUREG. Subsequently, the seismic capacity for the group of cabinets was evaluated, which manifests a great influence on the probabilistic seismic risk assessment of the facility. The main thrust of this study was the significant alteration in the seismic capacity due to the grouping effects that account for 28% and 50% reduction in the probability of failure for two and three cabinets together. This effect can be considered as one of the important aspects that can induce a considerable impact on the seismic capacity evaluation and performance of the NPP electrical components.