Development of Seismic Hazard Curves Based on Existing PSHA

DOE-STD-1023-95

3.1.2.1 Development of Seismic Hazard Curves Based on Existing PSHA

This option allows the use of existing PSHA studies similar to those conducted by the Electric Power

Research Institute (EPRI, 1989a) for the commercial nuclear power industry and Lawrence

Livermore National Laboratory (LLNL) (Bernreuter, et al., 1989) for the U.S. Nuclear Regulatory

Commission (USNRC), which can be used at particular DOE sites in the Eastern United States.

Experience has shown that application of the 1989 LLNL and EPRI methodologies can yield

significantly different results. It is permissible to directly average the mean hazard curves from

EPRI (1989a) and more recent hazard assessments from LLNL (Savy, et al., 1993 and Sobel, 1994).

The United States Geological Survey has completed probabilistic seismic hazard estimates for the

entire United States (USGS, 1996, USGS, 2001). While the USGS (1996) has stated that these

curves do not consider the uncertainty in seismicity or fault parameters, the USGS (2001) seismic

hazard curves should be compared to those available for the site. Differences in seismic hazard

estimates should be evaluated, after adjustments have been made to ensure these comparisons apply

to similar site conditions. The technical basis for the differences must be understood and documented

to validate the adequacy of the site-specific seismic hazard estimates.

This option is particularly suitable for DOE sites in the eastern United States, with the exception of

sites located near active sources for large magnitude earthquakes, e.g., near New Madrid, Missouri

and Charleston, South Carolina. In these cases, it is required to either incorporate additional site-

specific seismic sources or show that the regional seismic sources in the LLNL EPRI, or USGS

studies adequately model the tectonics in the vicinity of the site.

3.1.2.2 Development of Seismic Hazard Curves Based on New Site-Specific PSHA

Acceptable methodologies for conducting new PSHA for DOE sites should be consistent with

SSHAC (1997), Recommendations for Probabilistic Seismic Hazard Analysis: Guidance of

Uncertainty and Use of Experts (NUREG/CR-6372). As discussed in SSHAC (1997), an acceptable

methodology for the development of DOE site-specific seismic hazard curves must accommodate

uncertainties in the potential earthquake occurrence and ground motion attenuation processes

affecting the site.

The description given here applies to facilities with SSCs in PC 4, as specified in Section 3.1.1.f. For

PC 3, the same methodology as for PC 4 is required, but simplifications as described in Section

A3.1.2.2.5 are acceptable.

The following elements shall be included in the methodology to conduct a new PSHA.

(1)

Basic Hazard Model - The four steps required to determine the seismic hazard curve using the

basic hazard model are shown in Fig. 3.1.

(2)

Data Used in the Hazard Modeling - The PSHA shall consider available data in conformance

with DOE-STD-1022-94.