Methodology for selection of the most damaging ground motions for nuclear power plant structures

A methodology for selecting the most unfavorable ground motions (MUGMs) for practical dynamic analyses of nuclear power plant (NPP) systems is proposed. A series of correlation analyses are carried out to select relevant intensity measures (IMs) that best characterize structural demand parameters and consequently the damage potential of ground motions on NPP structures. Predictive demand models are developed as a function of the selected IMs using a large suite of as-recorded ground motions. A damage index is defined and the MUGMs were identified according to the estimated damage values. The reliability of the methodology is verified by comparing the identified MUGMs with the “actual MUGMs” that resulted in the peak damage values among all dynamic simulations. As an alternative to traditional spectrum-based record selection methods, the proposed methodology will ensure a very low risk of failure of NPP structures under the design level earthquake and can be utilized in seismic margin assessment.