ML20093L016
| ML20093L016 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 07/27/1984 |
| From: | Blake E GEORGIA POWER CO., SHAW, PITTMAN, POTTS & TROWBRIDGE |
| To: | Linenberger G, Margulies M, Paris D Atomic Safety and Licensing Board Panel |
| References | |
| RTR-NUREG-CR-3756 OL, NUDOCS 8407310270 | |
| Download: ML20093L016 (29) | |
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i SHAW, PITTMAN, PoTTs & TROWBRIDGE A PARTNERSMIP oF PeoFESStoNAL ComponATacN$
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Doc, h g' M g Mr. Gustave A. Linenberger,$j;{E Jr. <
ER Morton B. Margulies, Esq., Chairman ,
Administrative Law Judge Administrative Judge Atomic Safety and Licensing Board Atomic Safety and Licensing Board U.S Nuclear Regulatory Commission U.S. Nuclear Regulatory Commission Wasnington, D.C. 20555 Washington, D.C. 20555 Dr. Oscar H. Paris Administrative Judge Atomic Safety and Licensing Board U.S. Nuclear Regulatory Commission Washington, D.C. 20555 In the Matter of Georgia Power Company, et al.
(Vogtle Electric Generating Plant, Units 1 and 2)
Docket Nos. 50-424 and 50-425 o/ -
Dear Sirs:
By le'tter dated July 12, 1984, the Board asked the NRC Staff to respond to the question whether Board Notification 82-122A and NUREG/CR-3756 constitute " substantial new information" bearing on seismic design, and what effect this might have on the Staff's position with respect to GANE/ CPG contention 5. The letter provided all participants in this proceeding the opportunity te comment.
Applicants provide the following comments.
In Board Notification 82-122A, the Division of Licensing, Office of Nuclear Reactor Regulation, informed the Boards of the November 18, 1982 USGS letter, which Petitioners cited in their proposed contention, and of the Staff's recommended plan to conduct further study to evaluate its significance. Subsequently, the Staff formulated their plan of action and explained it in considerable detail in a Memorandum from Richard Vollmer to Harcld
.Denton (March 2, 1983) (Attachment I hereto) . In their response to Petitioners' contentions, Applicants cited the March 2, 1983 8407310270 840727 PDR ADOCK 05000424
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a SHAw, PITTMAN. PoTTs & TROWBRIDGE A PAstTNE85Her OF D3DOFEtgaONAL CO#80mAflONS Morton B. Margulies, Esq., Chairman Mr. Gustave A. Linenberger, Jr.
Dr. Oscar H. Paris July 27, 1984 Page 2 Memorandum and indicated that generic studies were underway.
Applicants' Response to GANE and CPG Supplements to Petitions for Leave to Intervene (May 7, 1984) at 37-38.
In April, 1984, NUREG/CR-3756 was published. It provides a seismic probabilistic risk assessment of ten sites in the Eastern United States, one of those sites being Plant Vogtle.
NUREG/CR-3756, however, is a preliminary report released to provide a summary of progress to date. Because it has not yet been subjected to peer review, the NRC cautions that the numerical results should be viewed with caution. The NRC does not anticipate final results until late 1984. Memorandum for James P. . Knight'from Robert E. Jackson (April 10, 1984)
(Attachment 2 hereto).
With respect to the admissibility of a safety contention, such as GANE/ CPG-5, the relevant inquiry is not whether tnere is "new" information, but whether information provided supports the contention -- in this case Petitioners' assertion that Applicants have not properly assessed the geology of the site because of the alleged possibility of a high intensity earthquake, such as recorded in Charleston in 1886, occurring near the Vogtle site.
The adequacy of Applicants' assessment and the Vogtle seismic design must be judged against regulatory requirements. 10 C.F.R. Part 100, Appendix A provides these requirements and calls for a deterministic, not probabilistic, evaluation.
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In their May 7, 1984 Response, Applicants described their treatment of the Charleston Earthquake, as fully discussed in the FSAR, in order to illustrate how their compliance with 10 C.F.R. Part 100, Appendix A was ignored and unchallenged by Petitioners.
Applicants pointed out that they had indeed fully analyzed the significance of the 1886 Intensity X Charleston earthquake. This earthquake is associated with a zone of seismic activity in the Charleston-Sommerville area. Accordingly, Applicants derived their safe shutdown and operating basis earthquake based on an earthquake of the same intensity as the Charleston earthquake occurring at the closest approach of this -'ne to the site.
Applicants' May 7, 1984 Response discusset oth the USGS letter and the Staff's generic studies. Applica.cs found Petitioners' basis for their contention inadequate because nothing Petitioners said was inconsistent with Applicants' analysis or compliance with Appendix A.
l SHAW, PITTMAN, PoTTs & TROWBRIDGE
. mamcu-i.or re . tea mm rio~. l Morton B. Margulies, Esq., Chairman l Mr. Gustave A. Linenberger, Jr. ;
Dr. Oscar H. Paris July 27, 1984 Page 3 The publication of NUREG/CR-3756 did not cure this lack of basis for GANE/ CPG-5. NUREG/CR-3756 explores the innovative approach of a probabilistic evaluation of earthquakes, rather than the recognized regulatory' approach of deterministic evalua-tion. The probabilities it assigns to ground acceleration at the Vogtle site have, at this date, no regulatory significance --
no bearing on Applicants' compliance with the deterministic requirements of 10 C.F.R. Part 100, Appendix A. There are no standards for evaluating the results of NUREG/CR-3756. However, the results of NUREG/CR-3756 do indicate that Vogtle's seismic design basis is less likely to be exceeded than are the seismic design bases of seven of the other nine sites studied.
Applicants are aware of no change in the Staff's position, either with respect to the November 18, 1982 USGS letter in general or with respect to the Vogtle seismic design in particular.
Applicants submit that NUREG/CR-3756 does not provide a basis for GANE/ CPG-5, and that contention should be rejected.
Respectfully submitted,
(:wf%.#4sk.
Ernest L. Blake, Jr., P.C.
David R. Lewis Counsel for Applicants cc Per Service List
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UNITED STATES OF AMERICA
+ NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LICENSING BOARD In the Matter of )
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GEORGIA POWER COMPANY, ET AL. -~
) Docket Nos. 50-424
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50-425 (Vogtle Electric Generating Plant, )
Units 1 and 2) )
SERVICE LIST Morton B. Margulies, Chairman Atomic Safety and Licensing Appeal Atomic Safety and Licensing Board Board Panel U.S. Nuclear Regulatory Commission U.S. Nuclear Regulatory Commission
- Washington, D.C. 20555 Washington, D.C. 20555 Mr. Gustave A. Linenberger Docketing and Service Section Atomic Safety and Licensing Board Office of the Secretary l U.S. Nuclear Regulatory Commission U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Washington, D.C. 20555 Dr. Oscar H. Paris Bernard M. Bordenick, Esq.
Atomic Safety and Licensing Board Office of Executive Legal Director U.S. Nuclear Regulatory Commission U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Washington, D.C. 20555 Atomic Safety and Licensing Board Tim Johnson Panel Campaign for a Prosperous Georgia U.S. Nuclear Regulatory Commission 175 Trinity Avenue. S.W.
Washington, D.C. 20555 Atlanta, GA 30303 -
Douglas C. Teper Carol A. Stangler 1253 Lenox Circle 425 Euclid Terrace
! Atlanta, GA 30306 Atlanta, GA 30307 Jeanne Shorthouse Dan Feig 507 Atlanta Avenue 1130 Alta Avenue Atlanta, GA 30315 Atlanta, GA 30307 l
r Laurie Fowler & Vicki Breman Legal Environmental Assistance Foundation 1102 Healey Building Atlanta, GA 30303 l
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( - ATTAChlMENT 1
/ g NUCLEAR REGULATORY COMMISSION UNITED STATES 2, wasamorow.o.c.aosas
- MAR 021983 MEMORANDUM FOR: Harold R. Denton, Director Office of Nuclear Reactor Regulation FROM: Richard H. Vollmer, Director Division of Engineering
SUBJECT:
DIVISION OF ENGINEERING GEOSCIENCE PLAN TO ADDRESS USGS CLARIFICATION RELATING TO SEISMIC DESIGN EARTHQUAKES IN THE EASTERN SEA 8OARD OF THE UNITED STATES A plan for our proposed program to address the U. S. Geological Survey's clarification of position relating to seismic design earthquakes in the Eastern Seaboard of the United States is attached (enclosure 1). Thi:s plan elaborates on the outline provided as an attachment to a memorandum entitled, " Clarification of U. 5. Geological Survey Position Relating to Seismic Design Earthquakes in the Eastern Seaboard of the United.
States", which was sent from the Executive Director of Operations to the Commissioners on November 19, 1982.
c The plan is divided into two parts. Part one is a short term probabilistic assessment utilizing an extensive new seismic hazard study currently being developed by Lawrence Livermore National Laboratory.
Part two is a longer term deterministic assessment based primarily on long range ORES research with the possible need for utility sponsored
, investigations at some locations after an assessment of the long term research results. Additionally, we reconnend that an industry sponsored
- seismic hazard study be solicited.
We estimate that the effort to establish the seismic hazard level for the sites and make appropriate comparisons will take approximately three years to complete, utilizing staff resources of about 2.5-3.0 SY per year, and $300K per year in technical assistance funds. Our preliminary recommendations on which plants, if any, may need further evaluation 4
should be completed in mid-1984 Because of the required research effort, the deterministic element will not be synthesized until 1985.
The proposed program will complement ongoing PRA reviews and the seismic hazard spectra which are developed can also be used for future SEP evaluations. This program, therefore, is basically a continuation, with modification, of our ongoing work. This program does not include resources to complete a reevaluation effort for plants for which design spectra may need to be reevaluated. We reconnend that this contingency be considered and included in the operating plan for FY 84. This plan also presupposes that our interim position for licensing reviews (enclosure 2) is found to be acceptable by ACRS and ASLB while we
.. implement this program.
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. There is evidence to support this assumption in the recent Appeal Board decisiononSummer(ALA8-710).
We have also assessed our ability to implement this plan under the existing regulation, Appendix A to 10 CFR Part 100. We have concluded that, although Appendix A itself does not explicitly recognize the use of probabilistic methods, as a minimum they can be used to assist in reaching detenninistic judgements (Seabrook Remand, CLI80-33). It is not clear whether they can be used as the primary tool in setting appropriate ground motion levels. Therefore, we recomend that we implement a limited modification or clarifiestion of Appendix A as previously planned in conjunction with ORES as a parallel, yet independent effort, along with the Charleston plan. This modification has been recomended in SECY-79-300 and endorsed by the Siting Policy Task Force in NUREG-0625 and is necessary to reflect the current state of art. This modification will require an additional 1.0 SY per year for 2 years.
We recomend that you consider placing this effort equally under three~
resource areas - Operating Reactor Licensing Actions or Safety Technology, Systematic Evaluation Program for older operating plants, t
and Casework for ongoing OL review plants.
' This plan has been developed as a result of extensive discussion within the Geosciences Branch, NRR; and discussions with the Earth Sciences Branch, ORES; and the U. S. Geological Survey.
b fy.lbr. -
Richard H. Vollmer, Director Division of Engineering
Enclosure:
As stated cc: w/ enclosure E. Case A. Murphy D. Eisenhut T. Schmidt R. Vollmer W. Russell R. Mattson R. Bernero H. Thompson GSB Staff J. Knight Z. Rosztoczy R. Jackson P. Williams l L. Reiter S. Broccum i T. Sullivan i
L. Beratan l R..Minogue s F. Arsenault l J. Scinto i
3 Enclosure 1 Pecommended Plan Eastern U. 5. Earthquakes Introduction On November 18, 1982, the U. S. Geological Survey (USGS) forwarded a letter to the Nuclear Regulatory Commission clarifying their past position with respect to the 1886 Charleston earthquake. The USGS letter states that:
"Because the geologic and tectonic features of the Charleston region are similar to those in other regions of the eastern seaboard, we conclude that although there is no recent or historical evidence that. other regions have experienced strong earthquakes, the historical record is not, of itself, sufficient grounds for ruling out the occurrence in these other regions of strong seismic ground motions similar to those experienced near Charleston in 1886. A1,though the probability of strong ground motion due to an earthquake in any given year at a particular location in the eastern seaboard may be very low, deterministic and probabilistic evaluations of the seismic hazard should be made for individual sites in the eastern seaboard to establish the seismic engineering parameters for critical facilities."
We have evaluated the USGS clarification of position and have concluded that it can be addressed predominantly through existing programs at NRC with the possibility of additional requests for utility - sponsored work. We recommend that a two part program be implemented which will address both the deterministic and probabilistic elements mentioned by the USGS.
l Part 1 of the proposed program is a short term probabilistic assessment of plants in the eastern seaboard. This part of the plan is necessary because many of the current tectonic working, hypotheses are not amenacle i
to investigation by deterministic methods in the short term.
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F Part 2 of the proposed program is a longer term deterministic assessment of the causes of large earthquakes, such as the Charleston earthquake, in the eastern seaboard. Specific areas of relatively high seismicit'y and tectonic structures are identified which we recommend be addressed through the ORES long range research plan.
Based on our evaluation of the research results, some applicants or licensees may be required to investigate tectonic structures which may not have been previously identified during the licensing procedure.
Part 1 - Probabilistic Assessment Discussion The Nove.mber 18, 1982 letter from the USGS represents not so much a new understanding but rather a more explicit recognition of existing l uncertainties with respect to the causative structure and mechanism of the 1886 Charleston earthquake. Many hypotheses have been proposed as to the locale in the eastern seaboard of future Charleston-size earthquakes. Some of these could be very restrictive in location while i others would allow this earthquake to recur over very large areas.
i Presently, none of these hypotheses are definitive and all contain a l strong element of speculation.
Traditional deterministic approaches such as that outlined in Secticr 2.5.2 of the Standard Review Plan are not generally designed to deal
n 3-I with this situation. Probabilistic methods which allow for the consideration of many hypotheses, their associated credibilities, and the explicit incorporation of uncertainty are much better equipped to i
provide rational frameworks for decision making. The question that needs to be answered is:
Taking uncertainties into account, have licensing decisions for
, plants in the eastern seaboard (i.e., in the region affected by the USGS clarified position on the Charleston Earthquake) resulted in acceptable levels of assumed seismic hazard (exposure to earthquake ground motion) at the individual sites?
One means for answering the above question is a probabilistic assessment of seismic hazard at all nuclear power plant sites east of the Rocky Mountains. Since adequate or acceptable levels of seismic harard have not been explicitly defined in probabilistic terms, it,is assumed that the probability of seismic ground motion exceeding design levels implicitly associated with licensing decisions based upon traditioral methods in other regions of the U. S. east of the Rocky Mountains. is adequate; these other regions include areas such as the Central Stable
, Region and the Gulf Coastal Plain. The prime tool for carrying out this assessment is an updated version of the Uniform Hazard Methodology developed for the Systematic Evaluation Program by Lawrence Livermore Na'tional Laboratory (LLNL) and its subcontractor TERA Corporation. This 1
methodology relies upon the incorporation of diverse expert opinion witn i
regard to the input parameters needed to make probabilistic estimates. t
- As such, it does not rely upon single hypotheses which do not account
! for existing uncertainties but rather attempts to incorporate the
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hypotheses and their uncertainties into the computations.
Identification of plants (if any) in the eastern seaboard at which the probability of exceeding design-level ground motion is significantly greater than has been assumed at other locations may result in an integrated seismic evaluation and/or engineering reanalysis to assure the plant's ability to withstand a more severe earthquake. This study may also identify selected plants outside of the eastern seaboard whose design levels may be inappropriate, relative to other plants, with respect to the seismic hazard.
In addition, we are also initiating, through a technical assistar.ce contract, a study to better estimate ground motion from a large earthquake the size of the 1886 Ch1rleston event to gair a better understanding of how this ground motion should be represented.
Major Activities - Probabilistic Assessment The probabilistic assessment portion of the proposed program is divided into the following elements.
- 1. January thru April 1983 - Continue development of LLNL study including expert opinion surveys on seismic hazard erst of the Rocky Mountains. This study (Seismic Hazard Characterization of tre l
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Eastern U.S.) is presently underway as a ,ioint effort of NRR and I
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ORES. No additional resources above those already allocated are needed.
- 2. May 1983 thru December 1983 - Calculation .I seismic hazard spectra by LLNL for all nuclear power plant sites (approximately
- 75) east of the Rocky Mountains. An estimation of the probability of seismic ground motion exceeding the design level at each site, taking into account specific site conditions, will be completed and provided as a report. An additional 2.0 SY is needed for LLNL and 0.3 SY for NRC effort during this period.
- 3. September - December 1983 - Comparison of LLNL study with existing probabilistic studies such as Algermissen and others (1982). An additional 0.2 SY is needed for LLNL effort.
- 4. March 1983 - December 1983 - Sponsorship by the utilities of a probabilistic estimation of seismic hazard for all nuclear power plants east of the Rocky Mountains. This study, while not a requirement, is strongly recommended so as to complement the LLNL study and provide another independent assessment of seismic hazard.
An additional 0.1 SY needed for LLNL and 0.1 SY for NRC effort'.
- 5. December 1983-March 1984 - Using LLNL and other studies, the NRC staff will integrate this information and make comparisons of the probability of seismic ground motion exceeding design levels in the eastern seaboard with probabilities calculated at plants in the rest of the Eastern and Central U. S. Comparisons will be made in several ways including comparison by region alnne and by region and plant vintage. Plants in the eastern seaboard (if any) that are associated with significantly greater hazard than those elsewhere 1
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will-then be identified. Other comparisons may be needed, but will be decided upon after review of initial results. An additional 0.7 SY is needed for NRC effort.
- 6. April 1984-September 1984 - Assessment of initial conclusions regarding hazard in light of feedback from expert opinion on original input. A final letter report will be issued with a final recommendation on plants which need reevaluation. An additional 0.2 1
SY needed for LLNL and 0.2 SY for NRC effort.
- 7. January 1983-December 1933 , Ground motion estimates at different distances and site cc litions from a iarge Charleston type earthquake. Both theoretical and empirical estimates using data from recent earthquakes will be made. This study is presently being initiated through a technical assistance contract with LLNL.
No additional resources are regt; ired.
Status summary reports of research into probabilistic estimates of i
seismic hazard funded by ORES will be needed by December 1983 so as to incorporate them into task number 5.
Implementation of Probabilistic Assessment Results The implementation of results is outlined above in elements 5 and 6.
J NRR Staff and Cost Recuirements - Probabilistic Assessment The additional effort required for this portion of the program will be 2.5 SY for LLNL (1.9 in FY 83, 0.6 in FY 84) and 1.3 SY for NRC (0.3 in FY 83, 1.0 in FY 84). This staff effort can be accommodated w'ith the i
currently available resources in the Geosciences Branch because this 1 I
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program complements ongoing staff activities and may replace other staff activities for individual sites. This program does not include resources to complete the seismic evaluation and/or engineering reanalysis which some plants may require as a result of the i probabilistic elements.
Utility-Sponsored Study in Conjunction with the Probabilistic Assessment A recommended utility-sponsored study is outlined above in element 4 Schedule - Probabilistic Assessment The proposed schedule for implementing this plan appears in Table 1.
5 Part 2 - Deterministic Assessment Discussion The deterministic portion of the proposed program is designed to better understand the causes of large earthquakes, such as the Charleston earthquake, in the eastern seabcard. This effort may require some expansion of immediate and long term ORES programs. Increased i
understanding of the cause of seismicity in the eastern seaboard will l allow a reduction in the uncertainty in estimating the seismic hazard for nuclear power plants. The primary problem witti seismic hazard characterization in the eastern seaboard is that no causative mechanism
{ for seismicity has been identified to date and no surface offsets due to I
earthquakes are known. Although there are literally thousands of crustal structures known in the eastern seaboard, which, if they were active, could produce strong earthquakes, none have been demonstrated :-
s have been active during the Quaternary (the last two million years) er l - - - - , -- - - - --- - - - --- - --- - -- ~ '-
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proved to be capable. The result is that, to date, there has been no generally accepted association between eastern seismicity and crustal structure. !
The overall approach of the deterministic assessment is to study areas of relatively higher seismicity in the eastern seaboard to determine if l tectonic features and processes responsible for the seismicity can be identified and correlated. This will be pursued by crustal studies at i hypocentral depths to detennine if there is any correlation between crustal structures at hypocentral depths and the earthquake hypocenters.
, The primary tool for determining crustal structure at hypocentral depths will be the use of multi-channel seismic reflection profiles. The primary tools for locating the hypocenters will be the continued monitoring and analysis of earthquakes from the existing microearthquake nets. These nets will have to be maintained and upgraded in order to improve depth locations of hypocenters if there is to be an improved ability to correlate between hypocenters and tectonic structures at depths of up to 25 kilometers.
This research will be contracted and monitored by ORES, and does not represent a radical departure from past programs. Increased coordination between NRR and ORES will be required, however, to better define the problems that are to be resolved in order to improve our understanding of eastern seis;nicity in the licensing context. This portion of the program is designed to improve our ability to assess the adequacy of the design of nuclear facilities on the eastern seaboard.
The result, in part, will be surr.ary reports which will represent the current status of research including a review and synthesis of availab'e
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Major Activities - Deterministic Assessment The deterministic assessment portion of the proposed program is divided into the following elements appropriate to e ach region listed.
A. Charleston Region Since the causative mechanism of the Charleston earthquake of 1886 continues to be one of the primary unresolved problems in evaluating seismicity in the eastern seaboard, research in the Charleston area should continue with the goal of testing the various hypotheses as to the cause of the earthquake. In particular, emphasis should be placed on determining if suggested features such as the Ashley River and Woodst,ock Fault zones constitute the source zones of the Charleston earthquakes.
- 1. May 1983 " Workshop on the 1886 Charleston Earthquake and Its Implications for Today" - the U. S. Geological Survey and the scientific community will present a summary and evaluation of the tectonics and seismicity at Charleston.
- 2. September 1983 - ORES in consultation with the U. S. Geologt:M Survey and the scientific community should have a prngram ir place to test the most likely tectonic hypothesis for seismicity.
- 3. June 1984 - ORES presents the results of the program d s< ~r- w -y ., -- -w, g, ,-w- g_. - _ , < - - - - - ,_,my-,,_. _ ,,-_.-- ., -,__ n _ ,e. _.,,._,,..--,-
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of testing the highest-weighted hypothesis.
4 January 1985 - ORES presents sumary report describing the results of the Charleston work testing the highest-weighted tectonic hy'pothesis.
B. Ramapo Fault Zone The Ramapo Fault Zone, a Precambrian fault zone that was intermittently active until the Mesozoic, is the northwestern boundary of the Newark Triassic Basin. Low level seismicity occurs in the area and may be i
associated with the fault zone, however, the seismicity in the region forms a band 40 kilometers wide. Detailed field work and limited trenching and core drilling 50ggest that the Ramapo Fault has not been recently reactivated. The purpose of studying the fault is to establish whether there is a causal relationship between Mesozoic or older faults such as the Ramapo Fault and current seismicity in this area by determining the location and geometry of these faults at hypocentral depths.
- 1. April 1983 - ORES initiates a new evaluation of the Ramapo Fault. The study should include multi-channel seismic reflection profiling and other geophysical techniques such as in-situ stress measurements and geodetic measurements to determine the current state of stress at hypocentral depths.
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January 1984 - ORES presents preliminary results of the progran to date, and plans for the coming year.
- 3. January 1985 - ORES presents summary repnrt on this aspect of the Ramapo Fault Study including the identification and analysis of any seismic source zones.
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C. Central Virginia Seismic Zone Recent work by earth scientists at Virginia Polytechnic Institute have l I
suggested that there may be a relationship between the seismicity in l Central Virginia and the northeast trending thrust faults and decollement of the Piedmont crust of the Appalachian Orogenic Belt. The purpose of this part of the trogram is to continue evaluation of the relationship between the fat.1#.s and the earthquakes.
- 1. April 1983 - ORES presents a plan for undertaking the seismic reflection profiling, and applying other geophysical techniques such as geodetic measurements and in-situ stress measurements.
- 2. January 1984 - ORES presents the preliminary results or
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progress to date, and plans for the coming year.
- 3. January 1985 - ORES presents a summary report on the the Central Virginia Study including the potential identification and analysis of any seismic source zones.
D. Giles County, Virginia The Giles County Seismic Zone is a northeast trending linear zone of seismicity which apparently.is located beneath the decollement and thrust faults associated with the Valley & Ridge Province of the
, Appalachian Orogenic Belt. It has been suggested that the seismic zene has occurred as a reactivated northeast trending nonnal fault associated with the opening of the Proto-Atlantic (called the Iapatus) in the late Proterozoic and early Paleozoic (800-500 million years ago).
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. April 1983 - ORES initiates planning for the proposed researen.
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- 2. August 1983 - ORES initiates study of the Giles County structure using seismic reflection profiling.
- 3. April 1984 - ORES presents' preliminary results and plans for the coming year.
- 4. April 1985 - ORES presents su:nnary results of this phase of the research including the pot:ntial identificatioa and analysis of any seismic source zones. -
E. New England The research in New England has been underway for several years and will be continued. Increased emphasis should be placed on evaluation of the source mechanism for the New Brunswick and Gaza, N.H. earthquakes, the neotectonics of seismically active areas, and the orientation and I magnitude of the stress field in the seismihally active areas of the '
region. An in-situ stress measurement at hypocentral depths will be conduc,ted at Moodus. Depending on the results of the seismic reflection studies described acove, additional seismic reflection surveys may be conducted in seismically active areas of tiew England such as Moodus, Connecticut; New Hampshire; Massena, New York and New Brunswick, Canada.
- 1. April 1983 - ORES completes plans for stress measurefrent at
' Moodus.
- 2. August 1983 - Conduct stress measurements at Moodus.
- 3. April 1984 - ORES presents preliminary results of stress measurements and their relationship to the local seismicity 2M '
s tectonics.
- 4. January 1985 - ORES presents sumary results of stress measurements and other studies described above.
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, Implementation of Deterministic Assessment Results As the results from the deterministic studies become available, they will be evaluated, and, the effect, if any, on operating plants and plants in the Operating License stage of review will be determined. The need for additional evaluations of particular structures by utilities will be assessed as the information becomes available. Two problems will be addressed by the deterministic portion of the program; (1) whether or not the deterministic findings warrant any reassessment of the conclusions drawn from the probabilistic study; and (2) whether there are any particular tectonic structures which are associated with or.
l similar to tectonic structu'res associated with seismicity which, because of their proximity to individual sites, should be analyzed by the utilities. The above effort will take about two to three years (early 1985) to complete.
The impact of this research on nuclear power plants will be determined by the NRC staff with technical assistance contracts, i
if necessary.
j NRR Staff and Cost Recuirements - Determinittic Assessment This effort will require continuous communication among NRR, ORES and the contractors.
As research funds are limited and the amount of ti.e is short, careful interaction will be necessary to obtain the information required to allow a resolution of eastern seismicity. It is l
estimated that one staff year per year for three years will be necessary for NpR to implement this deterministic part of the overall plan.
The research effort will be funded by ORES and technical assistance contracts will be funded by NRR. It is estimated that for the i
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deterministic assessment, $200,000 may be required to implement the NRR technical assistance program 'to determine the impacts of the findings on the nuclear facilities in the eastern U. S.
Utility-SponsoredStu,dissasResultoftheD?terminfsticAsessment During FY 1933 no deterministic work by thel utilities is currently recommended, beyond that neressary to pursue their normal afforts to continue.to assess any hazards identified by them for their sites.
Af ter'the results. of the 'research are available and if any source zones are identified which have particular importance to specific sites or have impact on the probabilistic program, some utilities may be required to invest,igate structures in the vicinity of their plants.
Schedule - Deterministic Assessrant The proposed schedule for implementing tnis plan follows as Table 1.
0ur ability tosmeet this proposed schedule may be somewhat optimistic and is contingent on implementing the appropriate contracts. We will be better able to assess this schedule when the work'has been initiated.
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a REFERENCE Algermissen, S. T., D. M. Perkins, P. C. Thenhaus, S. L. Hanson, and B. L. Bender, 1982, Probabilistic Estimates of Maximum Acceleration and Velocity in Rock in the Contiguous United States, United States Department of Interior, Geological Survey. Open-File Report 82-1033, 99 p.
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Calendar Year Schedule for Probabilistic and Deteministic Seismic Hazard Program i
1983 1984 1985 i Part 1 Short Tem Meet with ACRS to Meet with ACRS to discuss Program to discuss Preliminary Recommendations
- 1. Update LLNL Seismic + Complete Methodology -
Hazard Methodology
- 2. Calculate Seismic + + Report with Spectra -
Hazard Spectra for
- Eastern Sites
! 3. Compare with other +
+ Report with Comparisons i
i available probability studies i
- 4. Initiation of Industry- +
+ Production of Study Results Sponsored Seismic Hazard Study Letter Report'with Preliminary Recosamendations
.l 5. . Comparison of Seismic + +
. Hazard at Sites + Final Recomunendations 9
j Initate Feedback Assess Impact on
- 6. Assessment of Impact of +
Expert Feedback + Previous Results i
Initiate Tac with LLN'.
i 7. Charleston Ground Motion +
+1ssue Report Study Table 1
. Calendar Year Schedule for Probabilistic and Deterministic Seismic Hazard Program '
1983 1984 1985 Part 2 Long Term Meet with ACRS to Meet with ACRS to discuss Program to discuss Preliminary Recommendations Workshop-Interim Progress Report on Results of Synthesis Hypothesis Testing Testing
- 1. Charleston Research + x x xx-----
Initiate Preliminary Sunnary
, Study Report Report
- 2. Ramapo Fault Research + x x xx-----
Initiate Preliminary Summary Study Results Report Report
- 3. Central Va. Research + x x xx------
i Initiation Preliminary Summary RFP of Study Results Report l 4. Giles County, Va. + x x x xx-----
Research 1
Stress
) Heasurements Conduct Preliminary Summary
) Plan Measurements Results Report
- 5. New England + x x x -------xx
- Seismotectonic Research 1
i Summarize Review Preliminary Evaluation Summary of of Determinsitic i
of Results of RES Source Zones Work
- 6. Assessment of Impact of + x x i +
Deterministic Studies j on Sites Table 1 (cont'd)
Enclosure 2
- l
/ Interim Position on Charleston Earthquake for L1 censing Proceeding The NRR Staff position with respect to the Intensity X 1886 Charleston I
earthquake has been that, in the context of the tectonic province l approach used for licensing nuclear power plants, this earthquake should be restricted to the Charleston vicinity. This position was based, in part, on information provided by the United States Geological Survey (USGS) in a letter dated December 30, 1980 from J. E. Devine to R. E.
Jackson (see Summer Safety Evaluation Report). The USGS has been reassessing its position and issued a clarification on November 18, 1982 in a letter from J. E. Devine to R. E. Jackson. As a result of this
- letter, a preliminary evaluation and outline for NRC action was forwarded to the Commission in a memorandum from W. J. Dircks on November 19, 1982.
The USGS letter states that:
"Because the geologic and tectonic features of the Charleston region are similar to those in other regions of the eastern seaboard, we conclude that although there is no recent or historical evidence that other regions have experienced strong earthquakes, the historical record is not, of itself, sufficient grounds for ruling out the occurrence in these other regions .of strong seismic ground motions similar to those experienced near
, Charleston in 1886. Although the probability of strong ground motion due to an earthquake in any given year at a particular location in the eastern seaboard may be very low, deteministic and probabilistic evaluations of the seismic hazard should be made for individual sites in the eastern seaboard to estattish the seismic engineering parameters for critical facilities."
The USGS clarification represents not so much a new understanding but rather a more explicit recognition of existing uncertainties with respect to the causative structure and mechanism of the 1886 Charlesten 1
earthquake. Many hypotheses have been proposed as to the locale in the eastern seaboard of future Charleston-size earthquakes. Some of these
._,,. - , . - _ _ _ . . _ _ _ , _ , - . - , , _e . .___,--_...___,_,,_.__,__,,.y ,__y. , - - - . . _m_.--,,,e,. , . , . _ , - . ,__,_m.. , _ ,.- w,.,.,,,,_w, ~,,, , , . , , - - . , , , . . . , - - , . . _ , , , , ,
O could be very restrictive in location while others would allow this earthquake to recur over very large areas. Presently, none of these hypotheses are definitive and all 'contain a strong element of speculation.
We are addressing this uncertainty in both longer-term deterministic and shorter-tenn probabilistic programs. The deterministic studies, funded primarily by the Office of Research of the NRC should reduce the uncertainty by better identifying (1) the causal mechanism of the Charleston earthquake and (2) the potential for the occurrence of large earthquakes throughout the eastern seaboard. The probabilistic studies, primarily that being conducted for NRC by Lawrence Livermore National Laboratory (LLNL) will take into account existing uncertainties. They will have as their aim to determine differences, if any, between the probabilities of seismic ground motion exceeding design levels in the eastern seaboard (i.e. as affected by the USGS clarified position on the Charleston earthquake) and the probabilities of seismic ground motion r
exceeding design levels elsewhere in the central and eastern U. S. t, Any plants where the probabilities of exceeding design level ground motions are significantly higher than those calculated for other plants l in the Central and Eastern U. S. will be identified and evaluated for possible further engineering analysis.
Given the speculative nature of the hypotheses with respect to the recurrence of large Charleston-type earthquakes as a result of our limited scientific knowledge and the generalized low probability associated with such events, we do not see a need for any action for l r.
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specific sites at this time. It is our position, as it has been in the past, that facilities should be designed to withst& W the recurrence of an earthquake the size of the 1886 earthquake in the vicinity of Charleston. At the conclusion of the shorter-term probabilistic program and during the longer-term deterministic studies, we will be assessing the need for a modified position with respect to specific sites.
s N
(
- i (b < ATTACEkENT :. I
. [g .a U"MTED STATES o,,
i ! n NUCLEAR REGULATORY COMMISSION 2 WASHINGTON, D. C. 20555 p$ .
Q%U l
i MEMORANDUM FOR: James P. Knight, Assistant Director for Components & Structures Engineering Division of Engineering FROM: Robert E. Jackson, Chief Geosciences Branch Division of Engineering
SUBJECT:
USE OF LLNL INTERIM REPORT: SEISMIC HAZARD CHARACTERIZATION PROGRAM Dr. Andrew Murphy,' project manager for the joint Office of Nuclear Reactor Regulation and Office of Nuclear Reactor Research, Seismic Hazard Characterization Project, has received the Interim report discussing the hazard methodology and showing initial results for the first ten sites. The purpose of this memorandum is to provide a summary of the progress on this project up to this point and to provide users of the interim report with a perspective on what additional work will be uncertaken between now and the :ompletion of this project. The reader is referred to the interim report for specific discussion of the -
technical details included in the hazard analysis.
In common with the hazard study undertaken for the Systematic Evaluation Program (SEP), extensive use is made of expert judgement to obtain the input data required to perform a seismic hazard analysis. Improvements and changes made since the SEP study, include:
- 1. Use of a larger seismicity panel to insure coverage of all regions east of the Rockies.
- 2. Compilation of seismicity panel judgements regarding the existence or non-existence and alternative shapes of seismic source zones.
- 3. The seismicity panel experts provideo all seismicity parameters for their individual source zones. These parameters include the earthquake occurrence rate and the upper magnitude cutcff.
4 Use of a separate ground motion .nodeling panel to provide judgements regarding the ground motion models to be used in the hazard analysis, and;
- 5. Incorporation of major computer. software modifications in order to provide a more complete, as compared to the SEP program, uncertainty analysis for each seismicity / ground motion expert.
- - - .a----- - - - - - J=
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The specific results, both haza'rd curves and uniform hazard spectrum, included in the interim report are prelirainaey in nature because the
' feedback process-(both seismicity and ground riotien panels) has not yet been completed. .It-is'known, as a result of the seismicity panel feedback meeting, that some of the panel experts will modify seismic
. source zonation and earthquake occurrence parameters. However, the study can be considered as state-of-the-art particularly with regard to 1
methodology improvements incorporating uncertainties in all hazard input parameters. Because pear review has not yet begun and because feedback is not yet completed, the specific numerical- results should be viewed with caution particularly with respect to validity of the absolute numbers. Presently, the hazard curves-and uniform hazard spectrum can be used to gain insight as to the range of the existing professional judgements in seismic source zonation, earthquake occurrence parameters and ground rotion models. Although the above caveats have been stated,
- Lawrence Livermore National Laboratory has concluded that, "the median hazard curve combined over all experts is a robust estimator and we would not expect to see this hazard curve change significantly as a i result of feedback and the inclusion of the final set. of ground motion models."
In comparing commercial PRA hazard results with the LLNL calculations (Millstone and Limerick), it is noted that large divergence exists
- particularly at frequencies less than 10" per year. At this time we do i not necessarily believe that one is wrong and the other is right. We
, are attempting to evaluate and determine to what extent this divergence is the result of inherent uncertainties in state-of-the-art hazard estimates or systematic errors in input assumptions. However, 4
substantial advances in our understanding of earthquake causality and t ground motion may be needed to significantly improve the picture.
In terms of the data included in the tables and figures in the interim report, some qualitative comments are offered. First, it appears as if the relative ranking of seismic hazard levels at the ten sites are consistent with our general perception of seismic hazard based largely on seismicity and with the SEP hazard results. As in the SEP study
, there is a wide range of opinions regarding both seismic source zonation and earthquake occurrence parameters. For some sites this will result in very lar exceedance)ge differences in inter-expert best (upestimate to factors hazardof 100 cJrves. in probabilityIt will of be interesting to see if the feedback loop reduces this variability.
Another aspect of the interim results involves the spectral shape of the uniform hazard spectrum. In general, it appears as if sites which have Safe Shutdown Earthquakes defined using the Regulatory Guide 1.60 response spectrum will have significantly lower probability of exceedance associated with the lower frequencies (near 1 Hz) compared to the higher frequencies (10 to 25 Hz). This conclusion, however, is likely to be somewhat site dependent, with sites in close proximity to
_- __ _ _ _ . _ . _ . _ _ _ _ . _-_ _ _-. . _ _ _ _ _ _ _ . _ ._, . - . = _
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t more frequent larger earthquakes having a more broad band uniform hazard spectral shape.
In conclusion, although the interim report includes specific results for the first ten test sites, these results should be treated with caution because peer review has not yet begun and because the feedback process of both the seismicity and ground motion panels has not been completed.
The most important aspect of this report is the extensive compilation of current expert opinion regarding seismic source zonation, earthquake occurrence rates and ground motion attenuation models. Completion of feedback, peer review, and the final results for the ten test sites are expected toward the end of 1984. At that time an assessment of the usefulness of these results will be made prior to developing hazard curves for all nuclear power plant east of the Rocky Mountains. This assessment was prepared by J. Kimball of. the Seismology Section.
9 ert E. ac , Ch ef Geosciences agch Division of En ineering
Contact:
J. Kimball (301-492-8999)
A. Murphy (301-427-4615) cc: R. Vollmer F. Arsenault L. Beratan J.' Richardson E. Sullivan L. Reiter S. Brocoum A. thrphy D. Guzy GSB Staff 4
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