Seismic Hazard Position

DOE-STD-1024-92

1.0

SEISMIC HAZARD POSITION

The seismic hazard position described below uses the annual

probabilities specified in DOE Order 5480.NPH and UCRL-15910

(DOE-STD-1020).

For those sites that have both LLNL and EPRI probabilistic seismic

hazard results the recommended approach is to either continue to

use the TERA, Inc. seismic hazard values or:

Use the peak ground acceleration probabilistic median

seismic hazard curves from both the LLNL, without LLNL

Expert #5 Attenuation, (hereafter referred to as LLNL-

AE5) and EPRI studies.

Enter the two studies at the target probability (i.e., at 2 x

10-4, 1 x 10-3 or 2 x 10-3 per DOE Order 5480.NPH or

UCRL-15910 (DOE-STD-1020) and geometrically average

the resulting two peak ground accelerations.

Multiply the resulting peak ground acceleration by 1.80 for

the probabilities of 1 x 10-3 and 2 x 10-3 and 1.65 for the

probability of 2 x 10-4 to represent uncertainty in the

hazard analysis.

Using the peak ground acceleration from 3 above, anchor a

median standardized spectral shape such as the median

spectral shape defined in NUREG/CR-0098 (Newmark and

Hall), or a deterministic site-specific derived median spectral

shape. In all cases the spectral shape should be consistent

with the rock or soil site conditions at the site in question.

The resulting response spectra should be compared to that

being used to establish the Design Basis Earthquake (DBE)

at each site. If the DBE spectral shape is lower than the

NUREG/CR-0098 spectral shape, it is recommended that a

site-specific spectral shape be developed.

For those sites who implement a deterministic site-specific

spectral shape, information contained in the probabilistic seismic

hazard analysis should be used to establish the appropriate

magnitude and distance. Interim guidance for the development of

deterministic spectral shape is provided in Appendix B. The TERA,

Inc. spectral shape shall not be used for future DBE assessments

if it is lower than the developed site-specific spectral shape. A

DOE Standard is being developed (Draft DOE-STD-1023) that will

provide specific criteria which can be used to develop site-specific

spectra. The DOE Standard will supersede the interim guidance

found in Appendix B. If a modern probabilistic seismic hazard