ML20132B537

Forwards ACRS Seismology Consultant Comments on NRR Charleston Plan & Plan Impact on Facility.License Procedure Change Postponement for 3 Yrs Inappropriate.Hazard Curves for Facilities to Be Examined & Need for Actions Indicated

ML20132B537
Person / Time
Site:	Catawba
Issue date:	03/29/1983
From:	Rolonda Jackson Office of Nuclear Reactor Regulation
To:	Knight J Office of Nuclear Reactor Regulation
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References
FOIA-85-363 NUDOCS 8304060131
Download: ML20132B537 (2)

Text

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MEMORANDUM FOR James P. Knight, Assistant Director for Components & Structures Engineering -

Division of Engineering FROM: Robert E. Jackson, Chief 1 Geosciences Branch Division of Engineering

SUBJECT:

ACRS CONSULTANT P. POMER0Y'S COMMENTS ON NRR CHARLESTON PLAN

As a result of his review of the DE Charleston Plan for the ACRS ~ ._ c .

Subcommittee on Catawba, Dr. Paul Pomeroy, an ACRS consultant on seismology, has forwarded his comments on this plan to the subcommittee chairman and its impact on Catawba (attached). ,

In general,he indicates that the plan postpones consideration of changes ,

in licensing procedures for three years in the hope that proposed programs will produce definitive results. He considers this

- . inappropriate and. recommends. that the resolution of the Charleston problem. ACRS Although talethere

_a leadership may be some rol.eCA __ .

philosophical difference between Dr. Pomeroy and the staff on the urgency of the issue and interpretation of the USGS letter we feel that he may misunderstand some parts of the staff's plan. In addition ,we plan to be examining hazard curves for these facilities in about one year and, if necessary we will be advising on~the need for any specific actions at that time.

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For example, with respect to his points:

a. The staff believes that some hypotheses would allow a '

_ . .. Charleston-sized earthquake to occur throughout a large percentage of the area of the eastern seaboard (for example, the decollement

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hypothesis). Other hypotheses would restrict a Charleston-sized

• event to a small percentage of the area (for example, hypotheses

-elated to spec 4#4c kinds and orientWnn nf f= Ltc)- A f.ew hypotheses may restrict a Charleston-sized earthquake to the region around Charleston (any hypothesis that states that there is .

,s,omething geologically or seismically unique about Charleston).

b. Many previous deterministic studies focused primarily on surface mapping with the intent of defining tectonic provinces. The results of these programs have indicated that there is little, if any, correlation between surface geological features and the location of epicenters. The proposed program is designed to discover causal mechanism of larce eastern earthquakes by studying the tectonic

, features by geological and geophysical techniques at depths that the quakes are occurring. By correlating tectonic features and

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location of hypocenters, along with information from other geophysical techniques, it is hoped that causal mechanism for , ,,

eastern earthquakes will be identified. Each causal mechanism that -

can be identified should help decrease uncertainties associated with seismic hazard. However, Pomeroy's observation could be correct- ~

maybe we won't reduce uncertainty but it seems that we have the obligation to keep trying.

c. The purpose of the LLNL study is not to supply a catal'og o'f possibilities with respect to different hypotheses as to the reoccurrence of the Charleston Earthquake, but rather to measure - .

the uncertainty by allowing experts to present and weigh those hypotheses they consider appropriate. If one hypothesis is not considered or is assigned little weight, then that is a reflection of its credibility. This is an important element of this program However, in addition to the LLNL study, NRC is also funding a study . . c-by the USGS to assess the impact of differing hypotheses without any measure of their credibility.

Dr. Pomaroy also indicated that the Charleston- Issue should remain an Open Item for Catawba. As discussed in our internal position we .

clearly do not believe this is called for based on our present

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Robert . Ja son, Chief GeosciencesJranch Divisi(or Engineering

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Attachment:

As stated cc: R. Vollmer GSB Staff ,

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