At the NPP site selection stage several sites are typically proposed and compared. The site seismic response as part of the overall seismic hazard is among the most important parameters of the site evaluation. When the sites are distant enough and have different local geological conditions the results of the seismic hazard assessment based on Ground Motion Prediction Equations accounting the type of soil deposits are sufficient to make the difference between the local responses of the different sites. For adjacent sites with similar geologic properties this approach can not reflect the differences between the different sites and does not give a reliable base to compare the candidate sites. In this case site specific response analyses are necessary to compare the parameters of the local soil response and choose the most suitable site. In this case-study, four closely located NPP sites underwent detailed analyses to obtain their local free-field responses. The uncertainty in the site specific geotechnical data was included in the simulations with the Latin Hypercube Experimental Design procedure. The seismic input consists of an extended set of real strong motions recorded at stations founded on rock or soils with well documented properties. The selected input motions reflect the results of the magnitude-distance deaggregation for the area specific PSHA. To rank the candidate sites their specific response spectra are compared to each other and to the Uniform Hazard Response Spectrum derived in the PSHA. The local modification effects of each site are discussed and the preferred site-candidate is nominated.
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