Seismic hazard and deaggregation assessment at the nuclear power plants (NPP) sites in Spain using an updated seismological database

Abstract

In this paper we present the results obtained in the seismic hazard reassessment at the sites, in the free field, of the seven Spanish nuclear power plants (NPPs), six of them are still operative till date. The computation was done using the spatially-smoothed seismicity approach, and an updated seismic catalog. In most cases, the results do not greatly differ from those previously reported. In addition, at two of these locations where the hazard levels were higher, we carried out a seismic deaggregation study. We were thus able to determine the characteristics of the seismicity responsible for seismic hazard in terms of distance, magnitude and azimuth. The results obtained show that seismic hazard at the Cofrentes NPP is entirely due to close-range seismicity (< 70 km), whereas hazard at the Almaraz NPP is due to earthquakes located from 190 to 350 km away. A clear limitation of this work is the fact that we cannot include into our seismic hazard assessment, at this stage, paleoseismic information for the Spanish NPP sites. Key words: Seismic hazard, deaggregation, nuclear power plant, operation basis earthquake, safe shutdown earthquake.