Probabilistic seismic hazard assessment for OL3 plant site in Finland

The main objective of this paper is to describe the Probabilistic Seismic Hazard Assessment methodology in order to investigate the overall seismic site characteristics to be followed in the construction phase Probabilistic Safety Assessment of Olkiluoto 3 Nuclear Power Plant in Finland. In addition, the paper describes the three major elements of a seismic Probabilistic Safety Assessment: probabilistic seismic hazard analysis (PSHA); seismic fragility analysis (SFA); and seismic systems analysis (SSA) including risk quantification. For each element, the methodology and software tools are described. For example, seismic hazard curves and ground motion spectra for OL3 will be developed and presented. The purpose of the present work is the estimation of seismic hazard in the territory of the nuclear power plant Olkiluoto3 in Eurajoki. Because there are no registered strong motion acceleration recordings of earthquakes in Finland, the earthquake recordings from Saguenay and Newcastle regions from Canada and Australia were taken as sources of initial data because of their geological and tectonic similarity to Fennoscandia. The probabilistic seismic hazard assessment consists of three parts: 1) source effects, 2) path effects, 3) site effects. The site effects phase of the study is not relevant to this study because the prospective target sites are located on solid bedrock. Theoretical bases of determination of seismic hazard, questions of seismicity of a southern part of Finland, initial data on earthquakes and techniques of their processing, are considered below. (authors)