Document: NUREG-0800
Document ID: 1121c8ce-ab70-416c-9784-421014a1b25b
Document Type: srp
Title: SEISMIC DESIGN PARAMETERS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1419/ML14198A460.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.7.1
CFR Part: 
CFR Title: 

Content:
procedures that are acceptable to the staff for defining the design response spectra in the free-field for use in developing the OBE and SSE design ground motion needed for the design of nuclear power plant SSCs. A. Design Response Spectra. For a standard plant design, the design response spectra can be developed based on smooth-shaped broadband spectra consistent with the site conditions postulated for the standard design. For a non- standard plant (e.g., combined license (COL) application referencing only an early site permit (ESP), a COL application not referencing a design certification (DC) and ESP, a construction permit (CP) application, or an operating license (OL) application), the design response spectra are typically developed from the site-specific ground motion response spectra (GMRS). The GMRS reviewed under SRP Section 2.5.2 are site-specific horizontal and vertical free-field GMRS determined at the ground surface or at the free-field outcrop of the uppermost in-situ competent material using performance-based procedures in accordance with RG 1.208. The performance-based site-specific GMRS transferred to the foundation level in the free-field is referred to as the foundation input response spectra (FIRS). Therefore, the FIRS meet the same performance requisite as the GMRS. Both the GMRS and the FIRS are defined as free-field outcrop1 response spectra. The FIRS is the starting point for conducting an SSI analysis and for making a one-to-one comparison of the seismic design capacity of the standard design and the site-specific seismic demand for a site. The FIRS for the vertical direction is obtained with the vertical to horizontal (V/H) ratios appropriate for the site. GMRS are those derived from the global understanding of the site soil layers above the rock condition as determined from the site exploration activities, and therefore, are unique to a particular site. Competent material is generally considered to be in-situ material having a minimum shear