Part A- Comments - Continued

DOE-STD-1024-92

LLNL-5

Slope b.

The slope was selected to be 3.5 after the work of Dr. Robert P. Kennedy.

This parameter exhibits a good stability across studies and across sites.

However, it does vary substantially between ground motion levels, and it does

vary somewhat, but less, between regions.

For example, I took some very rough estimates of the slope b from the mean

hazard curves in the LLNL-EUS study for two hazard levels for 6 sites,

arbitrarily chosen.

around 2 x 10-4

3.8 at 2 x 10-3

Milestone

b = 2.3

Pilgrim

1.9

3.4

Shearron Harris

2.5

4.3

Calvert Cliffs

3.8

5.4

Browns Ferry

1.0

1.8

Susquehanna

3.2

4.0

These numbers show two things:

The slope of b = 3.5 recommended by Dr. Kennedy seems appropriate

within the context of the proposed interim procedure for hazard levels

around 2 x 10-4.

The slope should be increased for higher hazard levels. A slope of

about 4.5 to 5.5 would be appropriate, from the above data (obtained

by multiplying 3.5 by the average of the ratios of b at 2 x 10-3 and 2 x

10-4 above.)

LLNL-6

If the interim document is intended to be distributed to all DOE offices for

actual engineering use, it would be beneficial to clarify some of the technical

language used i.e., geometric mean, ratios, ratios of ratios, etc. A simple

graphical display of the procedure would also facilitate a quick understanding.

LLNL-7

We have reviewed the interim position and find it generally acceptable with

the comments listed below.

The resolution of LLNL versus EPRI hazard curve methodology is very important

since it will affect the guidance for and execution of hazard determination at

DOE sites as required by DOE Order 5480.NPH. The interim guidance does not

resolve the methodology differences but intends to provide a mechanism to use

the results of the LLNL/EPRI studies which were conducted for nuclear power

A-6