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8 NUCLEAR REGULATORY COMMISSIONos j WASHINGTON, D, C. 20655

\...../NAY 0 81985

Dr. J. Carl Stepp

Electric Power Research Institute/ 3412 Hillview Avenue

k P.O. Box 10412Palo Alto, CA 94303

Dear Carl:

In response to your letters of April 11, 1985 which discuss the comparativeevaluations cf the LLNL and EPRI seismic hazard studies, it may beappropriate to review our basic perspective on this issue. As part of NRC'sresponse to the USGS clarification of its position with respect to theCharleston 1886 earthquake, the staff included a short-term probabilisticassessment of seismic hazard at all nuclear power plants east of the RockyMountains. This assessment, an update of a more limited LLNL study, hadbeen initiated prior to the USGS letter but took on greater importance aspart of the so-called " Charleston Program." The earlier version of the LLNLseismic hazard study (begun in 1978) had been used very successfully indetermining seismic reevaluation criteria for 9 sites in the SystematicEvaluation Program and in several licensing safety reviews. It underwent

; intensive staff, utility, ACRS and peer-panel review and was consideredfavorably in several licensing-board hearings. While there were individualutility studies, there was no coordinated response that could allow a,meaningful comparison to the LLNL study in the manner in which it was used.As a result we recommended in the " Charleston Program", that a unifiedutility study be conducted so as to allow such a comparison. - We were verypleased with the positive response by the industry in initiating the ongoingEPRI study. We are also pleased that the approach taken by EPRI is somewhatdifferent than that taken by LLNL. The-present status of seismic hazardevaluation at low probability levels is sufficiently uncertain such thatdifferent perspectives on the same problem are needed. Our aim, as in thepast, is to make decisions primarily based on relative estimates of,

i seismic hazard.

As a result of our meeting with the Executive Director for Operations (EDO)on November 7,1987, it was decided to delay calculations at most of thesites until the EPRI results 9 for test sites could be compared to the LLNL

: calculations at the same sites. This meeting was an important meeting and Iam enclosing a subsequent memorandum from the EDO which includes a short istatement on this delay.

The comparison with the EPRI results is an important part of ongoing 1comparisons with other seismic hazard studies. In the LLNL report (to be ipublished in May) final results are presented for the 10 test sites alongwith comparisons made with the SEP studies, individual utility studies, USGScalculations and historic hazard analysis. These, plus additional studiesi

: being carried out by the USGS, and of course, EPRI will allow us to make the

I 8601170370 851205PDR FOIABELL 85-535 PDR

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best use of seismic hazard calculations. Towards the end of the 1985, afterj we have seen the EPRI results, and the analyses of differences (if any)

between the two studies, we will decide whether and to what extent repollingof the LLNL panels is necessary before calculating the hazard at theremaining 65 sites in the central and eastern United States. We view theUSGS/NRC-sponsored conference on seismic hazard to be a very important -element in the comparative evaluation process. We are looking forward to

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LLNL, EPRI and the USGS presenting results of their studies at this meeting.'i Additional studies by EPRI and the USGS will be considered concurrently with

the LLNL calculations at the 65 sites. All available seismic hazard studies! will be considered by NRC in determining how to apply the results to the

" Charleston Issue."

I I might add that we are already using the LLNL studies outside the contextof this issue. The LLNL studies have been very helpful in reviewing severalseismic PRAs, operating license applications and in a seismic reevaluationprogram. In one case (Hope Creek), which was not one of the 10 initial

| sites, the applicant chose to use LLNL data and the LLNL methodology to: calculate hazard at the site and presented the results to the Advisory

Cemittee on Reactor Safeguards. With respect to schedule we see threeimportant meetings:

1. First Comparative LLNL/EPRI Evaluation Meeting, June. 18, 1985. We hope1 that by this meeting LLNL will have completed calculations for 9 sites

using the LLNL methodology with the EPRI ground motion model and theEPRI lower bound cut off. This will allow a direct comparison ofresults. We also hope that as part of this meeting EPRI will be ableto present a short tutorial on its methodology and results.

2. Second Comparative LLNL/EPRI Evaluation Meeting, November 5,1985. Atthis meeting the bulk of the LLNL and EPRI comparative evaluationswould be presented along with any the USGS has performed.

3. NRC/USGS Seismic Hazard Conference, November 25, 26, and 27,1985 inSan Francisco. Presentation and discussion of comparative LLNL/EPRI

, evaluations, in the context of general seismic hazard evaluation, toi the larger seismic hazard comunity.

We expect LLNL, EPRI and the USGS to come out with separate reports andcomparisons. It has beer our experience that in seismic hazard evaluation,as in many other areas of the earth science, the most robust conclusionsthat NRC can effect come about through the encouragement of separate andindependent analysis. Whether and how these analyses will appear in onevolume is one of the items that needs clarification,

j With respect to the National Academy of Science / National Research CouncilPanel or seismic hazard evaluation, we view this NRC initiated effort as a

: longer range view of what the capabilities are and where we expect to go inthe future. We do not expect this panel to recommend particular

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methodologies although they have expressed a keen interest in receivingcopies of both the LLNL and EPRI studies and participating in the NRC/USGSconference in November.

In conclusion, NRC views the LLNL, and EPRI studies as playing importantroles in resolving ongoing seismological problems. We do not expect work inthis area to stop with the publication of these and other studies.Additional updated methodologies and calculations will undoubtedly be neededas our understanding increases.

I would be happy to meet with you again to discuss any additionalcoordination that you feel is necessary. I look forward to hearing from

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you.

Sincerely

Leon Reiter, LeaderSeismology SectionGeosciences Branch

cc: w/ enclosureP. SobelG. Giese-KochJ. KnightSherwood H. Smith, Jr.Ruble A. ThomasJohn J. Taylor EPRIWalter B. Loewenstein, EPRIIan B. Wall, EPRIJerry King, EPRIDon Bernreuter, LLNL

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United States Department of the Interiori=# GEOLOGICAL SURVEY

# RESTON, VA. 22092

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In Reply Refer To:Mail Stop 905 May 17,1985

Memorandum

To: Keiiti Aki, University of Southern CaliforniaTed Algermissen, USGSDon Bernreuter, LLNLKen Campbell, USGSKevin Coppersmith, Geomatrix Inc.Allin Cornell, Stanford UniversityA. Der Kiuregian, University of California, BerkeleyRobin McGuire, Risk Inc.Chris Mortgat, TERA Corp.Otto Nuttli, St. Louis UniversityDavid Perkins, USGSMaurice Power, Geomatrix Inc.Leon Reiter, NRCHaresh Shah, Stanford UniversityBurton Stemmons, University of NevadaCarl Stepp, EPRINafi Toksoz, MITDaniel Veneziano, MIT

From: Walter Hays, Chairman of Steering Committee

Subject: Workshop on "Probabilistic Earthquake llazards Assessments,"San Francisco, California, November 25-27, 1985

On behalf of the steering committee, I am inviting you to participate in thesubject workshop cosponsored by the U.S. Nuclear Regulatory Commission and theU.S. Geological Survey (USGS) .

We are requesting that you prepare a "draf t paper" of at least 8 pages on thetheme identified by-your name in the enclosed preliminary program. Pleasefollow the format of the enclosed example. You will have 60 days af ter the

meeting to finalize your paper before publication as a USGS Open-File Report.

We will reimburse non government participants for their travel costs inaccordance with current government regulations. Please let me know within 30days if you can participate in what promises to be a very interesting andvaluable meeting.

Enclosure

cc: Joe Berg

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WORKSHOP ON PROBABILISTIC EARTHQUAKE HAZ,ARDS ASSESSMENTS,

Fisherman's Wharf Matriott HotelSan Francisco, California

- November 25-27,,1985

Sponsors : U.S. Nuclear Regulatory Commission and U.S. Geological Survey

Objectives: 1) To review the methodology and results of recent studies toassess earthquake hazards probabilistically, and 2) to identifypractical and innovative ways to improve the overall state-of-knowledge.

Preliminary Program

(Note: The program will be refined to incorporate suggestions up to the dateof the meeting.)

Monday, November 25

1-1/2 hrs. Review of Methodology--Studies conducted by Lawrence LivermoreNational Laboratory KLLNL) and Electric Power Research Institute

1 (EPRI) will be featured. Differences will be identified and; discussed.

| --Carl Stepp, EPRI (will organize presentation)--Don Bernreuter, LLNL (will organize presentation)'

BREAK

1-1/2 hrs. Discussion of Methodology--Two participants will lead the initialdiscussion of the methodologies used by LLNL and EPRI. Everyonewill take part.

--Haresh Shah, Stanford University--Otto Nuttli, St. Louis University

LUNCH

1-1/2 hrs. Review of Results and Comparisons

--Don Bernreuter, LLNL (will organize ~ presentation)--Carl Stepp, EPRI (will organize presentation)

1-1/2 hrs. Discussion of Results--Two participants will lead the initial-discussion of the results obtained by EPRI and LLNL and theircompa risons. Everyone will take part.

--Maurice Power, Geomatrix, Inc.--Ken Campbell, USGS

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Tuesday, November 26

1 hr. Historical Seismicity and Tectonic Information--What is the roleof historical methods of analysis versus zonation methodologiesnow being applied in the Eastern and Western United States?

--Daniel Veneziano, MIT--David Perkins, USGS

1/2 hr. Discussion of Presentations--One participant will lead the initialdiscussion of this issue. Eieryone will take part.

--Chris Mortgat, TERRA Corp.

BREAK

4 hrs. Problems Associated with Describing Seismic Source ZonesProbabilistically--A series of presentations focusing on currentproblems of interest and concern. Discussion .to clarify issueswill be permitted during presentation.

(Note: Lunch will be taken midway in the session.)

Type of Faulting, Subduction Zones, etc.--Kevin Coppersmith, Geomatrix Inc.

Earthquake Frequency Distribution, Characteristic Earthquakes,Non-Poissonian Models, Attenuation, Seismic Gaps, etc.--Robin McGuire, Risk Inc.

Directivity, Finite Faults, Complex Descriptions of Ground Motion,Uncertainty, etc.

--A. Der Kiuregian, University of California, Berkeley

Maximum and Minimum Magnitude Estimation, etc.--Burton Slemmons, University of Nevada

1/2 hr. Additional Discussion of Presentations--One participant will leadthe initial discussion of these problems. Everyone will takepart.

--Nafi Toksoz , MIT

Wednesday, November 27

1 hr. Where do we go from here?--Two presentations suggesting innovativeways to increase the state-of-knowledge needed to make significantadvances in probabilistic hazards assessments.

--Allin Cornell, Stanford University--Ted Algermissen, USGS

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1/2 hr.- Discussion of Presentations ,,

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BREAK

2 hrs. What are the present capabilites, limitations, and the appropriatenext steps?--A panel discussion describing where we are now and

i suggesting practical plans or proposed actions to increase thecurrent state-of-knowledge.

--Keiiti Aki, University of Southern California'

--Robin McGuire, Risk Inc.--Carl Stepp. EPRI--Don Bernreuter, LLNL--Leon Reiter, NRC--Ted Al germissen, USGS

1/2 hr. Closure -

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INCREASING BAZARD AWARENESS AND PERSONAL PREP WESS

by' Os ?- $p +

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Boulder, Colorado 80309 Og# /e4

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00q 7* O| The title of this session suggests that there is an association between f#0 ,*oi increased hazard awareness and increased personal preparedness. In this

paper, th'e extent to which such a linkage exists will be discussed, as well asthe implications of this relationship for public policy particularly public

education campaigns.

At the outset, it is important to determine both the current and the optimumlevels of-awareness of the earthquake hazard in the Virgin Islands. Althoughthe Virgin Islands have experienced numerous earthquake.s, the level of

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i awareness of such earthquake susceptibility by either the resident or visitingpopulation is not known. However, one suspects that resident awareness in the

Virgin Islands is less than that observed in a state such as California with a

history of major damaging earthquakes and an extremely active program of

; public and private efforts to increase awareness and mitigation behavior. Theadoption of mitigation acasures directly related to the Virgin Islands

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earthquake hazard could also be assumed to be less than the level observed for'

California - which means that it is highly likely that only a minority of the

papulation have earthquake insurance policies on their horses,. and few peoplehave taken preparedness measures related to the earthquake hazard.

COMMUNICATION CHANNELS<

What sorts of campaigns should be taken then, both to increase generalawareness of the earthquake hazard, and more importantly, to induce personalpreparedness?

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#" 'o UNITED STATES~ , ,,E NUCLEAR REGULATORY COMMISSION* g*; y WASHINGTON, D. C. 20555

' ' . . . . * DEC 2 41984.

MEMORANDUM FOR: Chairman PalladinoComissioner RobertsComissioner AsselstineComissioner Bernthal .Comissioner Zech

FROM: William J. DircksExecutive Director for Operations

SUBJECT: PROGRESS REPORT AND SCHEDULE CHANGE IN NRC PROGRAMPLAN RELATING TO CLARIFICATION OF U. S. GE0 LOGICALSURVEY POSITION REGARDING SEISMIC DESIGN EARTHQUAKESIN THE EASTERN SEAB0ARD OF THE UNITED STATES

For the purpose of licensing nuclear facilities in the Southeastern U. S.,the NRC staff has taken a position, based primarily on the advice of theU. S. Geological Survey (USGS), that any reoccurrence of the 1886Charleston, S.C. earthquake would be confined to the Charleston area; thatis, the Charleston earthquake is assumed to be associated with a geologicstructure in the Charleston area. The effect of this position is thatnuclear power plants in the region east of the Appalachian Mountains areusually controlled in their seismic design, according to Appendix A to 10CFR Part 100, by the maximum historical earthquake not associated with ageologic structure. This controlling earthquake is typically a ModifiedMercalli Intensity (MMI) VII or VIII whereas the Charleston earthquake wasa MMI X. Since 1974, the NRC has funded an extensive research project togain further information on the causative mechanism of the Charlestonearthquake.

In a letter dated November 18, 1982 from James F. Devine, USGS to RobertE. Jackson, NRC, the USGS~ clarified its position indicating that:

"Because the geologic and tectonic features of the Charleston regionare similar to those in other regions of the eastern seaboard, weconclude that although there is no recent or historical evidence thatother regions have experienced strong earthquakes, the historicalrecord is not, of itself, sufficient grounds for ruling out theoccurrence in these other regions of strong seismic ground motionssimilar to those experienced near Charleston in 1886. Although theprobability of strong ground motion due to an earthquake in any givenyear at a particular location in the eastern seaboard may be very1cw, deterministic and probabilistic evaluations of the seismichazard should be made for individual sites in the eastern seaboard toestablish the seismic engineering parameters for critical ,facilities." |

Contact:R. H. Vollmer, NRR492-7207 f$ M 7 L

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In a Comission Paper dated February 5,1982 (SECY-82-53), we informed theComission of the possibility of modification in the USGS position and ina memorandum dated November 19, 1982, the USGS clarification was forwardedto the Comission along with an assessment of significance and a pre-liminary plan to address the clarified USGS position. This plan wasdiscussed with the Comission in its November 19, 1983 meeting and a jointNRR/RES program was initiated. The joint program consisted of a shorttem probabilistic program that has as its core a Lawrence LivermoreLaboratory (LLNL) estimation of seismic hazard at all nuclear power plantsites east of the Rocky Mountains, and a long term deterministic programthrough RES to determine the causes of large earthquakes, such as theCharleston earthquake, in the eastern seaboard.

With regard to the short term probabilistic program, final calculations by -LLNL are almost complete for 10 test sites. As a means of comparison werecomended in our original program plan that a utility sponsored studyalso be carried out. The utility study, being conducted through theElectric Power Research Institute.(EPRI), is currently scheduled forcompletion in April 1985. We have decided to defer LLNL's estimation of;the seismic hazard at the 65 remaining eastern sites for approximately 1year so as to await completion of the EPRI program and allow a thoroughcomparison of EPRI and other seismic hazard estimates to be.made. Theoriginal plan called for this comparison to take place concurrent withLLNL's calculations, however, we believe this change to be useful in lightof the rapidly evolving technology of seismic hazard estimation. As aresult the probabilistic portion of the plan to address the clarificationof the U. S. Geological Survey's Position on the 1886 Charleston Earth-quake will be available at the end of 1: 96, instead of in 1985 asoriginally scheduled.

The long term deterministic program is also progressing. Most signif-icantly, several teams of investigators, mainly funded by NRC, have foundevidence. of paleoliquefaction in the Charleston area. This is the firstindication of large to moderate earthquakes in the eastern seaboard inprehistoric times. It is possible that a seismic recurrence interval for

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large earthquakes in the Charleston area may be developed and that adetemination can be made whether or not this area is seismically unique.These conclusions await further investigations' and assessment.

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(SignsiD William J.Dirck

William J. DircksExecutive Director for Operations

cc: SECYOPE

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