Available interferometric data from recent earthquakes clearly show that major earthquakes produce large crustal deformation in wide areas. As a consequence these large areas undergo stress variations that may have significant consequences that need to be considered in the analysis of seismic hazards for the site of an NPP. The major issue is related to fault displacement hazard. This has special significance especially for the acceptability of NPP sites. Fault capability (i.e. potential for surface or near surface rupture) is one of the important exclusion factors for the siting of nuclear installations. While, in general, special care is taken not to site NPPs near major causative faults, it is not always easy to avoid siting in the proximity of secondary tectonic structures that may have the capacity for coseismic surface or near surface rupture. Although, the surface rupture related to these structures would be much smaller than those related to the causative fault, nuclear regulations as yet do not prescribe the amount of rupture that can be tolerated by NPP foundations. In this paper, a performance based risk informed approach is proposed. The methodology is based on axiomatic informed engineering judgement. This approach has already been used for one NPP and proposed for another one, both of which are located in tectonically active regions.
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