Document: NRC Regulatory Guide
Document ID: cfc61809-5745-460f-8a26-13c168659924
Document Type: regulatory_guide
Title: Identification and Characterization of Seismic Sources and Determination of Safe Shutdown Earthquake Ground Motion
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0037/ML003740084.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.165
CFR Part: 
CFR Title: 

Content:
ggregated for the matrix of magnitude and distance bins as given in Table C.1. A complete probabilistic hazard analysis was per formed for each bin to determine the contribution to the hazard from all earthquakes within the bin, e.g., all earthquakes with magnitudes 6 to 6.5 and distance 25 to 50 km from the site. See Figure C.2 where the median 1 Hz hazard curve is plotted for distance bin 25 - 50 km and magnitude bin 6 - 6.5. The hazard vaiues corresponding to the ground motion levels found in step 2, and listed in Table C.2, are then determined from the hazard curve for each bin for spectral accelerations at 1, 2.5, 5, and 10 Hz. This process is illustrated in Figure C.2. The vertical line corresponds to the value 88 cm/s/s listed in Table C.2 for the 1 Hz hazard curve and intersects the hazard curve for the 25 - 50 bin, 6 - 6.5 bin at a hazard value (probability of exceedance) of 2.14E-08 per year. Tables C.4 to C.7 list the appropriate hazard value for each bin for 1, 2.5, 5, and 10 Hz respectively. It should be noted that if the median hazard in each of the 35 bins is added up it does not equal 1.0E--05. That is because the sum of the median of each of the bins does not equal the overall median. However, if we gave the mean hazard for each bin it would add up to the overall mean hazard curve. Step 4 Using de-aggregated median hazard results, the fractional contribution of each magnitude-distance pair to the total hazard is determined. Tables C.8 and C.9 show P(m,d)I and P(m,d)2 for the average of 1 and 2.5 Hz and 5 and 10 Hz, respectively. Step 5 Because the contribution of the distance bins greater than 100 km in Table C.8 contains more than 5% of the total hazard for the average of 1 and 2.5 Hz, the controlling earthquake for the spectral average of 1 and 2.5 Hz will be calculated using magnitude-distance bins for distance greater than 100 kmn. Table C.1O shows P>I00 (md)l for the average of 1 to 2.5 Hz. 1,165-19 ,II Table C.2 Ground Motion Levels Frequency