Document: NUREG-0800
Document ID: 95092d51-3e9a-45e7-bd1c-dbc359279b98
Document Type: srp
Title: -
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1319/ML13198A223.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.7.2
CFR Part: 
CFR Title: 

Content:
Revision 4 – September 2013 locations, is indicative of an insufficient number of discrete mass degrees of freedom. v. When using either the response spectrum method or the modal superposition time history method, responses associated with high frequency modes (i.e., f > ZPA [or PGA] frequency) should be included in the total dynamic solution using the guidance and methods described in Regulatory Guide (RG) 1.92, Regulatory Positions C.1.4 and C.1.5. vi. Consideration of maximum relative displacements between adjacent supports of seismic Category I SSCs. vii. 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 conservative 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 simplified static analysis method accounts for the relative motion between all points of support. iii. To obtain an equivalent static load for an SSC that can be represented by a simple model, a factor of 1.5 is applied to the peak spectral acceleration of the applicable ground or floor response spectrum. A factor less than 1.5 may be used, if adequate justification is provided. 2. Natural Frequencies and Responses. To be acceptable, the following information should be provided: A. A summary of modal masses, effective masses, natural frequencies, mode shapes, modal and total responses for the seismic Category I structures, including the containment structure, or a summary of the total responses if the method of direct integration is used. B. The calculated time histories (two horizontal and one vertical), or other parameters of motion, or response