Seismic hazard reassessment of an existing NPP in Slovenia

Abstract

A seismic hazard reassessment of the site of an existing nuclear power plant in Slovenia was performed. For probabilistic seismic hazard analysis, the extended basic approach laid out by Cornell in 1968 was applied (Cornell, 1968). The study was based on existing data only. To overcome the lack of data and to handle uncertainties in the data, a multiple model approach was applied. Tectonic interpretations, seismic source determinations and estimates of the uncertainty were made by three independent groups of earth-scientists. The delineation of seismic sources and the estimation of their parameters were defined by the distribution of earthquakes, by fault rupture sizes, and by fault slip rates. The Gutenberg–Richter doubly truncated exponential recurrence relationship was used for magnitude distribution. Lower-bound magnitude was set at 5.0 for all seismic sources. Maximum observed earthquakes and assumed fault rupture sizes were used as the main criteria for the estimation of upper-bound magnitudes of area and fault sources respectively. The activity rates were either based on the catalogue or estimated from the assessed average fault slip rates. Subjective weights were assigned to model alternatives and to source parameter alternatives. The results of the study are presented as seismic hazard curves and spectra.