Part A- Comments - Continued

DOE-STD-1024-92

NS-2

It now appears that the resolution of the technical issues associated with the

interim position will likely result in most of the newly selected earthquake

values being near the current UCRL-15910 values. Because of this and

because of the interim position's limited scope (i.e., it would apply to less than

half of the DOE sites for a period less than 24 months), we recommend that

continued use of the TERA, Inc. curve values be considered as an alternative

to any new interim position.

The limited scope of the draft interim position needs to be clearly recognized.

First as stated in the SWG report, it is intended to be used only until research

is completed in 18 to 24 months. Secondly, the draft interim position applies to

less than half of the DOE sites whose review level earthquakes are now

specified in Table 4-4 of UCRL-15910. That is, it does not apply to Paducah,

Rocky Flats, or any DOE facility west of, or in, the Rockies. (Unlike the TERA,

Inc. hazard curves, the LLNL and EPRI curves were developed only for the

Eastern United States.)

The proposed resolutions of issues discussed in comments below seem likely

to raise earthquake levels selected by the interim position for higher probability

earthquakes. This would result in most of the new earthquake values being

near the current UCRL-15910 values. Table 3 of the SWG report now implies

that the only significant "benefit" to using the draft interim position (instead of

Table 4-4 of UCRL-15910) would be for facilities of moderate hazard or less,

but this benefit now appears unreal. Because of this and because of the

interim position's limited scope, we recommend that continued use of the

TERA, Inc. seismic hazard curve values be considered as an alternative to

issuing any new interim position.

NS-3

As discussed in the April 10, 1992, meeting of the Seismic Experts Panel

developing criteria for high level waste storage tanks, there is a problem with

using UCRL-15910's performance-based criteria with seismic hazard curves

whose slopes differ from the TERA, Inc. curves. While the slopes of the

TERA, Inc. curves are fairly constant, the slopes of the LLNL and EPRI curves

vary over the range of interest. To directly use the current UCRL-15910

structural evaluation criteria, one must make an upwards adjustment to

earthquake levels derived by the draft interim position for facilities of moderate

hazard or less (i.e., for earthquakes with annual frequencies of 2 x 10-1 and 1

X 10-3). The details of this adjustment have been drafted by the above-

mentioned Seismic Expert Panel. These proposed changes should be closely

coordinated with any revision to the interim position and the development of

NE-70's natural phenomena evaluation guidelines.

A-2