Part A- Comments - Continued

DOE-STD-1024-92

EM-1

In general, the interim approach proposed is reasonable for what it is trying to

accomplish for the next two years. It is probably conservative with respect to

what is likely to result from the final reconciliation of the EPRI and LLNL

approaches, especially based on what we know of the improvements being

made to the LLNL approach through the hazard studies being performed for the

DOE on the NPR program.

Below are two potential alternatives to the DOE interim approach. It is possible

that these alternatives were already considered and rejected for one reason or

another. We are only stating that there appear to be some as opposed to

"essential," but we feel they are worthy of some consideration if none has

previously been given.

EM-2

The seismic hazard at a particular site is to a large extent determined by a

particular type of earthquake (e.g., magnitude, depth, focal mechanism, etc.)

with a particular path. A detailed consideration of these factors in the form of

local knowledge would reduce the attenuating model uncertainties. This, plus

the fact that for soil sites, even without the Expert 5 of LLNL study, the ratio for

peak ground acceleration of 0.20g (LLNL/EPRI) median seismic hazard is high

(namely 1.24, according to Table 1 of the interim position) the use of LLNL and

EPRI median curves by averaging them and multiplying by a factor 1.65 tends to

be too conservative.

For soil sites, the best approach would be to incorporate all local soil conditions,

potential for liquefaction, dynamic soil amplification and other such factors and

develop the seismic hazard model from basic raw data using proper attenuation

models. The median forecasted value of PGA can then be used for scaling the

response spectrum shape and site specific median response spectra can be

generated.

EM-3

As an alternate to recommendations in the draft "Interim Position" the

probabilistic method for EUS, presented in the Army Technical Manual TM-5-

810-10-1 Chapter 3, can be used to perform the seismic hazard analysis at the

target probability per UCRL-15910 until the results of the study to be conducted

by Sandia National Laboratories become available.

RHO-1

The subject guidance document for use of the LLNL and EPRI seismic hazard

studies at sites in the EUS sites was reviewed as requested in your April 24,

1992, memorandum. The guidance document was found to be thorough and

appropriately conservative. We have no specific criticism or suggested

revisions. Though the report does not apply directly to sites in the WUS, there

are several conclusions that, if incorporated into specific Orders or

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