Document: NUREG-0800
Document ID: b91646e8-0b07-4d85-a5e4-783b27cdcd88
Document Type: srp
Title: SEISMIC AND DYNAMIC QUALIFICATION OF MECHANICAL AND
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070286.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.10
CFR Part: 
CFR Title: 

Content:
n, and the conservatism in amplitude and frequency content should be demonstrated (i.e., the test response spectrum (TRS) should closely resemble and envelope the required response spectrum (RRS) over the critical frequency range). (5) Since seismic and the dynamic load excitation generally have a broad frequency content, multifrequency vibration input motion should be used. However, single frequency input motion, such as sine beats, is acceptable provided the characteristics of the required input motion indicate that the motion is dominated by one frequency (e.g., by structural filtering effects), or the anticipated response of the equipment is adequately represented by one mode, or in the case of structural integrity assurance, the input has sufficient intensity and duration to produce sufficiently high levels of stress for such assurance. Components that have been previously tested to IEEE Std 344-1971 should be reevaluated to justify the appropriateness of the input motion used, and requalified if necessary. (6) For the seismic and dynamic portion of the loads the test input motion should be applied to one vertical axis and one principal horizontal axis (or two orthogonal horizontal axes) simultaneously unless it can be demonstrated that the equipment response in the vertical direction is not sensitive to the vibratory motion in the horizontal direction, and vice versa. The time phasing of the inputs in the vertical and horizontal directions must be such that a purely rectilinear resultant input is avoided. An acceptable alternative is to test with vertical and horizontal inputs in-phase, and then repeat the test with inputs 180 degrees out-of-phase. In addition, the test must be repeated with the equipment rotated 90 degrees horizontally. DRAFT Rev. 3 - April 1996 3.10-6 Components that have been previously tested to IEEE Std 344-1971 should be requalified using biaxial test input motions unless justification for using a single axis test input motion is