The Anchorage, Alaska M7.1 Earthquake of November 30, 2018: Findings from a Post-Earthquake Investigation on Selected Power and Industrial Facilities

The Electric Power Research Institute (EPRI) Seismic Qualification Utility Group (SQUG) instituted a post-earthquake investigation program in 1985 to facilitate the collection of experience data relevant to the nuclear power industry. The goal of the program is to advance the use of earthquake experience data as a cost-effective method for seismic qualification and fragility evaluation of nuclear power plant (NPP) equipment. EPRI continues to update the database by collecting experience data from new earthquakes to expand the volume and diversity of the data and confirm the established equipment class caveats and definitions in light of contemporary seismic events. Reviews of new earthquakes are prioritized based on the epicentral ground motion accelerations, the presence of industrial sites with equipment similar to typical nuclear installations, the likelihood of accessing these sites to document the equipment performance, the equipment diversity and vintage, and known instances of abnormal performance that could augment the existing experience. On November 30, 2018, Anchorage, Alaska, and surrounding areas were shaken by a M7.1 earthquake centered 16 km north of downtown. EPRI visited a total of sixteen sites located in the epicentral region following the earthquake, including three substations, seven power generating plants, and three water/wastewater treatment plants. This earthquake was of particular interest to EPRI because a significant number of facilities were subjected to relatively large ground motions. The site operators were also interested in working with EPRI on the investigation of their facilities, providing important insights on the equipment and system configuration and performance. Moreover, several power facilities were constructed within the last ten years, which afforded an opportunity to evaluate the applicability of SQUG guidance to newer vintage equipment. EPRI 3002018221 (2020a) documents the details of this EPRI investigation. This paper summarizes the main findings of that report and focuses on the most important lessons learned for the nuclear power industry.