Examples

DOE-STD-1024-92

5.0

EXAMPLES

The approach was used to develop representative peak ground

acceleration estimates for five sites which were made available to the

S WG; Savannah River, Portsmouth, Oak Ridge, Princeton and Brookhaven.

Table 2 shows the peak ground acceleration values for the three

probabilities defined in UCRL-15910 (DOE-STD-1020), the actual LLNL and

EPRI median, mean and 85th percentile values at these probabilities, and

the older TERA, Inc. estimates. Table 3 shows the resulting estimate of

the pseudo-mean value, and a comparison to the older TERA, Inc.

estimates reported in UCRL-15910 (DOE-STD-1020). Table 3 also shows

the recommended approach for Brookhaven and Princeton, sites that only

have the LLNL seismic hazard curves.

As shown in Table 3, the recommended values are equal to or lower than

the previous estimates provided in UCRL-15910 (DOE-STD-1020). This

result is significant when considering that the older hazard curves are

labeled "best estimate" values which may be most appropriately correlated

with median estimates, considering that TERA, Inc. did not explicitly

quantify modeling uncertainty. This would qualitatively suggest that median

seismic hazard estimates have decreased since the late 1970's. Tables 2

and 3 also show that if the option selected had directly used the mean or

85th percentile data, the derived pseudo-mean is likely to have been

heavily influenced by the LLNL curves. Table 3 also shows that the

recommended values are equal to or greater than the EPRI 85th percentile,

but significantly lower than the LLNL 85th percentile. Based on the above,

it is acceptable for sites in the Eastern United States to continue to use the

TERA, Inc. peak acceleration or the values recommended by this Standard.

Table 4 displays the recommended peak horizontal acceleration values in

summary fashion. Table 4 also lists the remaining Eastern United States

DOE sites. The S WG is unaware of whether LLNL or EPRI data exists for

these sites and thus continues to recommend the use of TERA, Inc.

results.

The Standard explicitly applies to all DOE sites east of the about 104W. The

Rocky Flats Site is excluded from the Standard because the LLNL and EPRI

studies did not extend far enough westward to provide the necessary seismic

hazard input. The Paducah, Kentucky site is excluded because this site is in

close proximity to the New Madrid, Missouri seismic zone which should be

modeled as an extended line source. Neither the EPRI or LLNL studies

adequately modeled the New Madrid source in this fashion. The Paducah site

has undertaken appropriate probabilistic seismic hazard studies including

extended source modeling for New Madrid. Department of Energy sites in the

Western United States (west of 104W) should be aware of the position,

particularly when developing site-specific probabilistic seismic hazard curves and

the assessment of uncertainty in deriving mean estimates of seismic hazard.