
 DOESTD102395
magnitude of earthquakes that were modeled for the source. Likewise, the level of recorded
ground motions for the event can be compared with the levels predicted in the seismic hazard
analysis. For additional guidance on the content and amount of documentation to support
PSHAs, SSHAC (1997) should be consulted.
A3.1.3.1a. The development of sitespecific spectral shapes for PC 3 SSCs may be relatively less rigorous
than those in PC 4. For example, the treatment of degradation and uncertainty in soil
properties in site response analysis may be made by using generic characteristics rather
than using data from sitespecific tests. The bounding limits of magnitudes and distances for
collecting data may also be reduced.
A3.1.3.1b. An acceptable approach for the development of sitespecific DBE response spectra includes the
steps summarized below:
Step 1:
From the sitespecific probabilistic seismic hazard analysis results, use the mean
seismic hazard curve showing the annual probability of exceedance as a function
of the SA (for additional guidance on this and subsequent steps, see USNRC,
1997 Regulatory Guide 1.165). It is recommended that, as part of the
information database, the following deaggregation procedure also be applied to
median hazard results.
Using the appropriate annual probability of exceedance value, PH (e.g., 1x104
Step 2:
for PC 4), enter the hazard curve from Step 1 at PH to determine the
corresponding SA.
Step 3:
Deaggregate the mean SA seismic hazard curve as a function of magnitude and
distance and calculate the contribution to this hazard curve for all of the
earthquakes in a selected earthquake magnitude and distance set (size M x N) to
determine the relative contribution to the hazard. This requires the calculation of
the annual probability of exceedance, H(mi,rj), for each magnitude/distance bin:
magnitude mi (i =1,2,..,M) and distance rj, (j =1,2,...,N).
Step 4:
Compute the magnitude of the controlling earthquake for the mean estimates of
SA (510) using the contributions H(mi, rj) computed in Step 3 in accordance
with the following (or similar) equation:
M N
M N
mi H(mi,rj) /
H(mi,rj)
M(1) =
i=1 j=1
i=1 j=1
A5

Privacy Statement  Press Release  Copyright Information.  Contact Us 