ML20126D563

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Summary of 791116 Meeting W/Applicant Re Seismology
ML20126D563
Person / Time
Site: San Onofre  Southern California Edison icon.png
Issue date: 11/20/1979
From: Stampelos J
Advisory Committee on Reactor Safeguards
To: Bender M
Advisory Committee on Reactor Safeguards
Shared Package
ML20126D553 List:
References
ACRS-SM-0177, ACRS-SM-177, NUDOCS 8005020186
Download: ML20126D563 (7)


Text

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f/U NITED STATES v {

%, NUCLEAR REGULATORY COMMISSION U / $ ADVISORY COMMITTEE ON REACTOR SAFEGUARDS '

W ASHINGTON, D. C. 20555 800502 0\])J

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Novenber 20, 1979 l Hyer Bender , Chainnan, San Onofre Subcommittee SAN ON0FRE (#2 and #3) SEISMOLOGY MEETING (Washington, D.C.;

Novenber 16,1979)

Ref: Seismic Meeting on San Onofre, Sept. 1978 .

(Attachment 1)  ;

r Th: NRC Staff met with the apolicants, the applicant's consultant (Woodward-Clyde), the United States Geological Survey, and NRC consultants to discuss ,

the specific earthquake magnitude and ground motion acceleration attributable to the Hypothesized Offshore Zone of Deformation (0ZD). In 1972 the Atomic  ;

Energy Corrmission and its consultants agreed to a 2/3 g design basis earth-quake for the Safety Evaluation Report (SER). A conservatively large earth-quake was postulated for a fault 5 miles offshore from the site. No earth- [,

quake magnitude, however, was estimated for the 0ZD. As of August 1979, '  !

l' nits 2 and 3 were respectively 74% and 60% complete and scheduled for com- ,

t.arcial operation in 10/80 and 1/82.  !

i The NRC Staff is preparing questions on a report prepared by the applicant's consultant (Woodward-Clyde, " Report on the Evaluation of Maximum Earthquake  :

I and Site Ground Motion Parametery associated with the Offshore Zone of Deformation, San Onofre Nuclear Gene' rating Station," June 1979; a sunraary is included in the attachments, a full copy has been requested).

This meeting stressed the following points to be addressed in the applicant's n2 port:

1. Slip rate is based on gathering historical data.

Why can we rely on this data? What is the sensitivity of slip rate.to earthquake magnitude? How would the discovery of new data points effect Woodward-Clyde's

' tectonic model? Sensitivity analysis should be employed.

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2. The probability of seeing various g values'at the plant should be evaluated. The recurrence of different magnitudes of earthquake and their effect or challenge to the plant should be evaluated. ,
3. The NRC does not have an approved tectonic model for the site area.

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4. Woodward-Clyde's seismic analysis should include '

all data bases even though the quality of foreign j information may require further evaluation,

5. How does the maximum magnitude earthquake mentioned in the Woodward-Clyde report relate to the requirerents of 10 CFR 100 (Appendix A)?

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The next meeting on this subject is scheduled for the week ending December 21, 1979.  ;

,r.,~ 19 ~ l f .

I f.'-(. )[dy:s E Y ohn Stampelos ACRS Fellow

/ ttachments :

1. Summary of Seismic Meeting, Sept.1978 '
2. Summary of the Woodward-Clyde Report * '
3. Program Development Plans
a. Development of maximum magnitude for the OZD
b. Development of site ground motion parameters
4. Approximate relationships between intensity, acceleration and magnitude for earthquakes
5. Faulting Offshore of Southern California (2 page map) .

cc: ACRS Members ACRS Technical Staff J. Maxwell .

B.M. Page S.S. Philbrick

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