General Design Criterion 2 of Appendix A of 10 CFR Part 50′ requires that nuclear power plant structures. systems, and components important to safety be designed to withstand the effects of earthquakes without loss of capability to perform their safety functions. It is the purpose of these criteria to set forth the principal seismic and geologic considerations which guide the Atomic Energy Commission in its evaluation of the suitability of proposed sites for nuclear power plants and the suitability of the plant design bases established in consideration ‘of the seismic and geologic characteristic of the proposed sites. Appendix A of 10 CFR Part 100, “Se~mic and Geologic Siting Criteria for Nuclear Power Plants,” requires the following two types of earthquakes for the analysis and design of nuclear power plants. The safe shutdown earthquake (SSE) is that earthquake which is based upon an evaluation of the maximum earthquake potential. considering regional and local geology and seismology and specific characteristics of local subsurface material. It is thar earthquake which produces the maximum vibratory ground motion for which certain structures, systems, and components are designed to remain functional. These structures, systems, and components an: those necessary to assure: I. The integrity of the reactor coolant pressure boundary 2. The capability to shut down the reactor and maintain it in a safe shutdown condition 3. The capability to prevent or mitigate the consequences of aCcidents which could result in potential offsite exposures of 10 CFR Part 100