Document: NUREG-0800
Document ID: a3c4cb91-c557-4043-bb50-8da01264de08
Document Type: srp
Title: Each calculated spectrum of the artificial time history is considered
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340564.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.0
CFR Part: 
CFR Title: 

Content:
um Aid nearly stationary power of aR acceleration time history record. Additional guidance on estimation of T for artificial time history or actual earthquake time history is provided in Rppendix B of Reference 6. The averge one-sided PSD defined by Equation (1) should exceed 80 percent of the target PSD as defined by Equation (2) from 0.3 Hz to 24 Hz. Less than 2.5 Hz So(W) 650 inch2/sec3 (f/2.5) 0° 2 2.5 Hz to 9.0 Hz SO(W) 650 inch2sec3 (2.5/f)1 8. . (2) 9.0 Hz to 16.0 Hz SO(W) = 64.8 inch2/sec3 (9.0/f)3 Greater than 16 Hz SO(W) = 11.5 inch2/sec3 (16.0/f)8 At any frequency f, the average PSD is computed over a frequency band width of ±20 percent centered on the frequency f (e.g., 4 to 6 Hz band width for f=5 Hz). The power above 24 Hz for the target PSD is so low as to be inconsequential so that checks above 24 Hz are unnecessary. (However, note that the response spectrum calculations are required beyond 24 Hz as governed by Regulatory Guide.1.60 definitions.) Similarly, power below 0.3 Hz has no influence on stiff nuclear plant facilities so that checks below 0.3 Hz are unnecessary. This minimum check is set at 80 percent of the target PSD so as to be suffi- ciently high to prevent a deficiency of power over any broad frequency band, but sufficiently low that this requirement introduces no additional conserva- tism over that already embodied in the Regulatory Guide 1.60 response spectrum. 3.7.1-11 Rev. 0 - August-1989 A time history meeting this minimum PSD requirement will produce a response spectrum that lies below the Regulatory Guide 1.60 response spectrum at all frequencies. To produce a response spectrum that accurately fits the 2 percent damped, 1.0g, Regulatory Guide 1.60 response spectrum at all frequencies above 0.25 Hz, the PSD defined by Equation (2) can be used with the resulting time history being clipped at ±l.Og (Ref. 7). To produce a response spectrum that conservatively envelops the 1.Og Regulatory Guide 1.60 response spectrum at 2 percent