Geology and seismology studies are becoming increasingly important in nuclear power plant siting decisions. Earthquake hazard assessment is perhaps the most challenging application of these disciplines to siting. Techniques for determination of the probabilities of damaging earthquakes and forecasting of seismic events need further development before they can be routinely applied as prescribed standards to power plant siting. Although the plate-tectonics model provides a functional explanation for the loci of earthquake activity along plate boundaries, the genesis of seismicity within lithospheric plates is less well understood. The seismic potential of numerous mapped, geologic structures in many portions of the North American continent are still matters of conjecture and disagreement.

The current siting criteria provide a normative procedure for establishing seismic design bases using the regional earthquake history and structural geology, together with detailed observations at the site. This process of prescribed analysis can, and has, led different investigators to contrasting conclusions.

States review the seismic design conclusions of the applicant utility and the safety evaluations of the Nuclear Regulatory Commission (NRC). Outside of the utilities and the NRC, the States are virtually the only other entities with scientific expertise that regularly participate in the siting process. The State role is usually advisory and nonregulatory. States contribute extensive knowledge of regional geology and seismicity to the decision-making process. Increasingly, the State geological surveys provide comments and suggestions to the Federal government and to utilities at an early enough stage so that an extensive and helpful dialogue precedes the State’s ultimate, formal review of siting reports.

In this discussion, we examine the State roles in determining the site-specific seismic-design bases for nuclear power plants. We consider the roles and perspectives of other parties as well. The scientific and procedural limitations that affect the siting process are analyzed. Finally, recommendations are made to improve the manner in which conclusions about seismic hazards at nuclear power plant sites are presented.