Document: NUREG-0800
Document ID: 29f5ac9f-4962-4021-913a-6375076e03fd
Document Type: srp
Title: SEISMIC SYSTEM ANALYSIS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340566.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.7.2
CFR Part: 
CFR Title: 

Content:
acceleration; for example, 33 cycles per second in the case of structures, equipment, and components excited directly by Regulatory Guide 1.60 design spectra). Therefore, a demonstration that adequate consideration is given to the high-frequency modes is required. (See Appendix A for acceptable methods to account for high-frequency modes.) (v) Consideration of maximum relative displacements among supports of Category I structures, systems, and components. (vi) Inclusion of significant effects such as piping interactions, externally applied structural restraints, hydrodynamic (both mass and stiffness effects) loads, and nonlinear responses. b. Equivalent Static Load Method An equivalent static load method is acceptable if: (i) Justification is provided that the system can be realistically represented by a simple model and the method produces conserva- 3.7.2-6 Rev. 2 - August 1989 I tive results in terms of responses. Typical examples or published results for similar structures may be submitted in support of the use of the simplified method. (ii) The design and associated simplified analysis account for the relative motion between all points of support. (iii) To obtain an equivalent static load of a structure, equipment, or component that can be represented by a simple model, a factor of 1.5 is applied to the peak acceleration of the applicable floor response spectrum. A factor of less than 1.5 may be used if adequate justification is provided. 2. Natural Frequencies and Response Loads To be acceptable for the operating license review, the following informa- tion should be provided: a. A summary of natural frequencies, mode shapes, modal and total responses for a representative number of major Category I structures, including the containment building, or a summary of the total responses if the method of direct integration is used. b. A time history of acceleration (or other parameters of motion) or response spectrum used in design at the major plant equipment eleva- I