Permanent ground displacements/deformations caused by earthquakes can seriously challenge
the safety of the nuclear power plants. The state-of-the-art hazard analysis methods
provide a fault displacement hazard curve, i.e., the annual probability of given measure
of displacement will be exceeded. The evaluation of ground displacement hazard requires
great effort, empirical evidence, and sufficient data for the characterization of
the fault activity and capability to cause permanent surface displacement. There are
practical cases when the fault at the site area revealed to be active, and, despite
this, there are no sufficient data for the evaluation of permanent ground displacements
hazard and for judging on the safety significance of permanent ground displacement.
For these cases, a methodology is proposed that is based on the seismotectonic modelling
and results of the probabilistic seismic hazard analysis. The method provides conservative
assessment of the annual probability of fault displacement that allows the decision
whether permanent displacement hazard is relevant to nuclear power plant safety. The
feasibility and applicability of the method is demonstrated for the Paks site, Hungary.
