Proposed modifications of NRC's standard review plan for seismic analysis

The paper briefly describes the major changes in seismic analysis and design criteria proposed in the U.S. NRC Standard Review Plan. The changes to the SRP also reflect the resolution of Unresolved Safety Issue (USI) A-40, 'Seismic Design Criteria'. The proposed revision provides explicit guidelines for (1) developing site-specific spectra; (2) determination of suitable design time history (ies); (3) the location of seismic input motion; (4) developing floor response spectra; (5) soil-structure interaction (SSI) analysis; (6) analysis of above-ground Seismic Category I tanks; and (7) analysis of buried piping and structures. The proposed revision, together with its background material, was issued for public comments on 19 May, 1988, together with a solicitation to address specific questions related to SSI analysis. These are discussed in the paper. The paper concludes with a note on the importance of the progress made and outlines the areas requiring further studies and research. (orig.)