Document: NUREG-0800
Document ID: c165ebfe-8431-4d56-8bc9-97c2227d45bb
Document Type: srp
Title: SEISMIC SYSTEM ANALYSIS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0706/ML070640311.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.7.2
CFR Part: 
CFR Title: 

Content:
alized coordinates. This method results in a nonproportional damping matrix for the composite structure, and equations of motion have to be solved by direct integration or by uncoupling them by use of complex eigenvectors. Other techniques for estimating the equivalent modal damping of a SSI model are reviewed on a case-by-case basis. 3.7.2-18 Revision 3 - March 2007 14. Determination of Seismic Overturning Moments and Sliding Forces for Seismic Category I Structures. To be acceptable, the determination of the design overturning moment and sliding force should incorporate the following items: A. Three components of input motion. B. Conservative consideration of the simultaneous action of vertical and horizontal seismic forces. Additional information on load combinations is provided in SRP Section 3.8.5. Technical Rationale The technical rationale for application of these acceptance criteria to the areas of review addressed by this SRP section is discussed in the following paragraphs: 1. 10 CFR Part 50, General Design Criterion (GDC) 2 requires, in the relevant parts, that SSCs important to safety be designed to withstand the effects of natural phenomena such as earthquakes, without loss of capability to perform their intended safety functions. GDC 2 further requires that the design bases reflect appropriate consideration for the most severe natural phenomena that have been historically reported for the site and surrounding area, with sufficient margin for the limited accuracy, quantity, and period of time in which the historical data have been accumulated in the past. These data shall be used to specify the design requirements of nuclear power plant components to be evaluated as part of construction permit (CP), operating license (OL), COL, early site permit reviews, or for site parameter envelopes in the case of design certifications, thereby ensuring that components important to safety will function in a manner that will maintain the plant in a safe condition. SRP