Document: NUREG-0800
Document ID: 1f106a50-722f-45fa-952a-2e7ab7d836c1
Document Type: srp
Title: DYNAMIC TESTING AND ANALYSIS OF SYSTEMS, COMPONENTS, AND EQUIPMENT
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052360453.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.9.2
CFR Part: 
CFR Title: 

Content:
ure participation-of all significant modes. The criterion for sufficiency is that the inclusion of additional modes does not result in more than a 10% increase in responses. 3.9.2-6 Rev. 2 - July 1981 (d) Consideration of maximum relative displacements among supports of Category I systems, and components. (e) Inclusion of significant effects such as piping inter- actions, externally applied structural restraints, hydrodynamic (both mass and stiffness effects) loads, and nonlinear responses. (2) Equilvalent Static Load Method An equilvalent static load method is acceptable if: (a) Justification is provided that the system can be realis- tically represented by a simple model and the method produces conservative results in terms of responses. Typical examples or published results for similar systems may be submitted in support of the use of the simplified method. (b) The design and associated simplified analysis account for the relative motion between all points of support. (c) To obtain an equivalent static load of equipment or component which 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. In addition, for equipment which can be modeled adequately as a one-degree-of-freedom system, the use of a static load equiva- lent to the peak of the floor response spectra is acceptable. For piping supported at only two points, the use of a static load equivalent to the peak of the floor response spectra is also acceptable. b. Determination of Number of Earthquake Cycles During the plant life at least one safe shutdown earthquake (SSE) and five operating basis earthquakes (OBE) should be assumed. The number of cycles per earthquake should be obtained from the synthetic time history (with a minimum duration of 10 seconds) used for the system analysis, or a minimum of 10 maximum stress cycles per earthquake may be assumed