ML17347B462

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App a to USI A-46 & Generic Ltr 87-02.
ML17347B462
Person / Time
Site: Saint Lucie, Turkey Point, 05000000
Issue date: 12/31/1989
From:
FLORIDA POWER & LIGHT CO.
To:
Shared Package
ML17347B461 List:
References
REF-GTECI-A-46, REF-GTECI-SC, TASK-A-46, TASK-OR GL-87-02, GL-87-2, NUDOCS 8912180161
Download: ML17347B462 (165)


Text

APPENDIX A UNRESOLVED SAFETY ISSUE (USI) A-46 GENERIC LETTER GL 87-02 FLORIDA POWER & LIGHT COMPANY DECEMBER 1989 8912180161 891213 PDR ADOCK 05000250 P P.DC

0 APPENDIX A INDEX TAB TITLE A-1 Technical and Economic Basis for the Exclusion of Relays from the Florida Power and Light Plant Specific Seismic Adequacy Implementation Procedure to Resolve Unresolved Safety Issue A-46 and Generic Letter 87-02 A-2 Symposium on Current Issues Related to Nuclear Power Plant Structures, Equipment and Piping with Emphasis on Resolution of Seismic Issues in Low Seismicity Regions Technical Pa ers (a) Probabilistic Seismic Hazard Results for Sites in a Region of Low Seismicity (b) History o f Seismological Activity in Florida:

Evidence of a Uniquely Stable Basement A-3 Duration of Strong Ground Motion: Proceedings of the Fifth World Conference on Earthquake Engineering, (1973) .

A-4 Uniform Hazard Spectra for the St. Lucie and Turkey Point Nuclear Power Plants Probabilistic Seismic Hazard Evaluation, St. Lucie and Turkey Point Nuclear Power Plant Sites (Executive Summary)

TECHNICAL AND ECONOMIC BASIS FOR THE EXCLUSION OF RELAYS FROM THE FPL PLANT SPECIFIC SEISMIC ADEQUACY IMPLEMENTATION PROCEDURE TO RESOLVE UNRESOLVED SAFETY ISSUE A-46 AND GENERIC LETTER GL 87-02 GL 87-02 is concerned that older plants (predating IEEE 344-75) may not. be able to achieve/maintain the hot shutdown condition in the event of a Safe Shutdown Earthquake (SSE).

GL 87-02 states that "Direct application of current seismic criteria to older plants could require extensive, and probably impractical modification of these facilities." GL 87-02 proposes a solution whereby older plants would be reviewed against new seismic criteria specifical'ly chosen for A-46 resolution, and acknowledges that these new seismic criteria are different than any previously licensed seismic criteria or any currently licensed seismic criteria.

The essence of this new seismic approach is that instead of using (10 CFR program 50 App. B) developed by test an and /or analysis programs industry group which it includes uses a new new generic ground response spectra; similarity comparisons with (non-nuclear) earthquake experience databases; and the judgement of qualified/experienced engineers. Due to the reviews proposed by GL 87-02 using this new program and due to there being no evidence to show that older plants do not presently have "adequate protection" in the context of the Backfit Rule (10 CFR 50.109), GL 87-02 acknowledges that the proposed resolution constitutes a backf it.

Included in the new program are seismic criteria which have never been required of any licensed nuclear plants, including those nuclear plants exempted from GL 87-02 by virtue of being IEEE 344-75 plants, such as St. Lucie Unit 2. One of these seismic criteria is the requirement that relays (including contactors and switches) be functional/free from chatter for a period of 30 seconds of strong shaking.

The purpose of this paper is to address this subject as to FPL's plants from seismological, operational, risk assessment, it applies licensing and economic perspectives and to show that it is entirely appropriate that relays be excluded from FPL's final plant specific implementation procedure.

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SUMMARY

OF CONCLUSIONS (1) Strong shaking of any duration is not credible at FPL's plants.

(2) St. Lucie Unit 2 was totally exempted from A-46 (via GL 87-

03) because it is licensed to current criteria (IEEE 75/RG 1.100 Rev.1). Neither the IEEE nor RG document require 344-relay chatter during strong shaking to be addressed.

(3) Future plants will be licensed to IEEE 344-87/RG 1.100 Rev.2.

The IEEE and RG documents only require relay chatter during the first 15 seconds of strong shaking to be addressed, which in GL 87-02 for older is 15 seconds less than the requirements plants.

(4) All seismic PRAs done to date using NRC approved methodologies (with the possible exception of Limerick s), did not assign relay chatter, any risk contribution to core melt. The PRA's considered relay chatter to not be an equipment failure but rather to be an event, which recoverable by operator action.

if it occurred at all, would be NUREG 1211, the Regulatory Analysis for A-46, written by the NRC for GL 87-02, did not assign relay chatter any risk contribution to core melt.

(6) NUREG/CR 4710 (St Lucie) and NUREG/CR 4762 (Turkey Point), the A-45 (Decay Heat Removal) analyses written by Sandia under contract to the NRC, examined the risk contributors to core melt from earthquake accelerations up to and including 4XSSE.

Sandia did not assign relay chatter any risk contribution to core melt, at either the St. Lucie plant or the Turkey Point plant.

(7) NRC approved criteria for the purpose of evaluating relays under the A-46 program do not exist.

(8) Required expenditures by FPL to address relays under the A-46 program would not be prudent.

DISCUSSION (1) Florida Seismicit State of the art seismic hazard studies have recently been completed by the Electric Power Research Institute (EPRI) for a utility owners group, and by Lawrence Livermore National Laboratories (LLNL) for the NRC. Neither the EPRI nor the NRC studies placed any seismic sources in Florida. Further, the University of Florida, a United States Geological Survey Station, presented a paper in December 1988 (Appendix A, Tab A-2) at the EPRI Seismic Symposium in Orlando, which concluded that the Florida land mass attached to North America during the Paleozoic era and that it is lithologically and tectonically distinct from and more stable than the (seismically active) Appalachian area which was the original margin of North America. In summary, Florida is legally, but not seismically, a part of the Eastern United States.

(2) Time Duration of Stron Shakin Strong shaking durations depend upon magnitude and source-to-site distance, with lesser dependencies on wave frequency and amplitude threshold. In 1973, Professor Bruce Bolt presented the definitive paper on the subject (Appendix A, Tab A-3) at the World Conference on Earthquake Engineering in Rome. The paper was, and still is, the only NRC approved reference document on the subject in NUREG-0800 (Standard Review Plan) Section 2.5.2 (Vibratory Ground Motion).

In accordance with Professor Bolt's paper, to have any duration of strong shaking at any of FPL's plants would require a Magnitude 5.5 earthquake within approximately 45 miles; a Magnitude 6.5 earthquake within approximately 75 miles; a Magnitude 7.5 earthquake within approximately 100 miles . None of these events can be considered as credible, considering Florida s seismicity.

As another example to illustrate the application of Professor Bolt's paper, the effects of the January 1986 Leroy, Ohio earthquake on the Perry plant are worth reviewing. The earthquake was centered approximately 10 miles from the plant and 'had a Magnitude of 5.0. The recorded duration of strong shaking was less than 1 second which is compatible with Professor Bolt's paper. In addition, although 39 safety related systems made up of several thousand components and devices were in operation or standby during the earthquake, all s stems functioned normall . The only relays which malfunctioned were the generator protection relays which tripped due to not having voltage applied because the plant was in the startup mode. Had they had voltage applied they most likely would not have tripped (EPRI NP-6389).

0 erator Action GL 87-02 states that "credit can be taken for timely operator action to reset relays in case change of state occurs during an SSE". This is the position taken by seismic PRAs to date and it. is the position taken by FPL in responding to A-46.

Rela Evaluation Efforts At the present time, the NRC's contractor, Brookhaven National Laboratories has taken the position that evaluation of relays to the new seismic criteria (GERS) is difficult and may not be possible on a generic basis.

The Steering Group for the industry group developing the new seismic approach has proposed a solution whereby the evaluation of relays would be accomplished by having a group of engineers experienced in both relays and seismic testing make similarity comparisons to previously qualified relays and then reach a judgement as to qualification by a consensus methodology (Seismic Qualification Utility Group Meeting Minutes of October 26 and 27, 1989).

This methodology may be appropriate for higher seismic risk utilities and may receive NRC approval for use. In the meantime, there is no NRC approved methodology for the purpose of evaluating relays under the A-46 program. The alternative is to replace the relays with IEEE 344-75/RG 1.100 Rev.l relays but this would require extensive modification to FPL's facilities, which has been recognized as impractical by GL 87-02 as stated earlier.

Economic Considerations Recently, the industry group developing the new approach was taken over by EPRI and EPRI's proposed charter limits the availability of the new seismic approach (including relay evaluation criteria) to paid members for a period of ten years. The charter further requires new members to pay an initiation fee equal to the sum of all payments made by original members. Since FPL has never been a member of the industry group, it would cost FPL hundreds of thousands of dollars in initiation fees to get the (proposed) relay evaluation criteria at this time.

Even if the relay evaluation criteria had NRC approval at this time, in order to use them FPL would have to prepare a list of essential relays required for hot shutdown. At each of FPL's three plants this would involve screening approximately 1000 to 2000 relays, 500 to 1000 circuit breakers/contactors, and 1000 switches, at an estimated cost of $ 200,000 to

$ 400,000 per plant.

The alternative to joining the EPRI industry group would be to replace existing relays with IEEE 344-75/RG 1.100 Rev.1 relays which also would cost hundreds of thousands of dollars and as stated earlier, would not provide qualification for strong shaking and would be impractical as recognized by GL 87-02.

In previously docketed correspondence (L-88-333/August 4, 1988) FPL made the point that the (potential) benefit of resolving A-46, calculated by using site specific data together with the NRC's methodology in the Regulatory Analysis for A-46 (NUREG-1211) was $ 15,000 for the St Lucie plant and

$ 8,000 for the Turkey Point plant. The (actual) implementation program being offered by FPL at this time already has a cost in excess of this (potential) benefit and further voluntary expenditures in the hundreds of thousands of dollars to additionally address relays under the A-46 program would not be prudent.

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g)ponsored by ELECTRIC POWER RESEARCH INSTITUTE SEISMICITY OWNERS GROUP NORTH CAROLINA STATE UNIVERSITY

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Background A symposium proceedings will be published and dis-In December 1986, the 1st Symposium on Current Issues tributed at the symposium. It is anticipated that selected Related to Nuclear Power Plant Structures, Equipment papers from the proceedings may be published in a spe-and Piping was held at North Carolina State University cial issue of Nuclear Engineering and Design.

(NCSU). The symposium was sponsored by NCSU and Purpose of the Second Symposium cosponsored by the U.S. Nuclear Regulatory Commis- The purpose of this 2nd Symposium is to address a broad sion (USNRC) and the Electric Power Research Institute range of nuclear plant issues with emphasis on resolu-(EPRI). In the two years since the first symposium, very tion of seismic issues in low seismicity regions.

significant advances have been made inunderstanding and resolving concerns particularly with respect to seis- Who Should Attend mic issues. Industry and the NRC have completed de- This symposium is directed to structural, geotechnical, velopment of probabilistic seismic hazardmethodologies, mechanical and plant operation engineers, engineering procedures for equipment qualification and seismic mar- managers, licensing engineers and managers working gins evaluation procedures. It is timely to review these in the area of nuclear power plants with electrical utilities, and other advances in resolving nuclear plant related and to regulatory personnel. Equipment manufacturers issues. and suppliers, architect-engineers and other consulting firms and research organizations will also benefit.

Technical Information For further information on the technical content of the program, contact:

Ajaya K. Gupta, Professor of Civil Engineering, North Carolina State University Raleigh, NC 27695-7908 ~ (919) 7377207

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Time T0esday, Dec. 6 Wednesday, Dec. 7 Thursday, Dec. 8 Friday, Dec. 9 7:00 am Continental Breakfast/

Registration 7:30 am Continental Breakfast Continental Breakfast 8:00 am Session I Session V Session IX Break Break Break Between 10-10:25 am Session II Session Vl Session X 12 NOON , LUNCH LUNCH LUNCH 1:30 pm Session III Session Vll Session XI Break Break Break Between 3-3:25 pm Session IV Session Vill Session XII 6:00 pm Reception/ Reception Symposium adjourns Early Registration 7:30 pm Dinner

Second Symposium on CURRENT ISSUES RELATED TO NUCLEAR POWER PLANT STRUCTURES, EQUIPMENT AND PIPING With Emphasis on Resolution of Seismic Issues in Low Seismicity Regions

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7:00 am SESSION II: SEISMIC HAZARD-2 Registration and Continental Breakfast Chairmen:

Walter W. Hays SESSION I: SEISMIC HAZARD-1 US. Geological Survey Chairmen: Reston, VA C. AllinCornell C. Allin Cornell Stanford University Stanford University Stanford, CA Stanford, CA Walter W. Hays US. Geological Survey 10:25-10:50 am Reston, VA Probabilistic Seismic Hazard 8:00-8:30 am Lessons Learned, A Regulator's Perspective Probabilistic Assessment of the Seismic Hazard Leon Reiter for Eastern United States Nuclear Power Plants US. Nuclear Regulatory Commission Don L. Bernreuter, Jean B, Savy and Richard W. Mensing Washington, D,C.

Lawrence Livermore National Laboratory 10:50-11:15 am Livermore, CA A Decision Framework Using Seismic 8:30-9:00 am Hazard Results to Address Issues Probabillstic Seismic Hazard Assessment: of Nuclear Power Plant Seismic Safety EPRI Methodology Robert T. Sewell Robin K. McGuire and Gabriel R. Toro

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Gabriel R. Toro and Robin K. McGuire Risk Engineering Incorporated Risk Engineering incorporated Golden, CO Golden, CO J. Carl Stepp J. Carl Stepp Electric Power Research Institute Electric Power Research Institute Palo Alto, CA Palo Alto, CA 11:15-11:40 am 9:00-9:30 am Lower Bound Earthquake Magnitude Probabilistic Seismic Hazard Assessment for Probabilistlc Seismic Hazard Evaluation Trends in USGS Approach Martin W. McCann, Jr. and John W. Reed David M. Perkins Jack R. Benjamin & Associates, Incorporated US. Geological Survey Mountain View, CA Golden, CO 11:40-12:00 9:30-9:50 am History of Seismological Activity in Florida Probabilistic Seismic Hazard Assessment- Douglas L. Smith and Anthony F. Randazzo A Utility Perspective Geohazards, Incorporated John P. Jacobson and Thomas F. O'ara Gainesville,NFL Yankee Atomic Electric Company I p, 4'e, I Framingham, MA el/If',

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9:50-10:10 am 12:00 m Luncheon Probabilistic Seismic Hazard Results Luncheon Speaker for Sites in a Region of Low Seismicity Commissioner Thomas M. Roberts, Samir G. Khoury and Umesh Chandra Nuclear Regulatory Commission EBAS CO Services Incorporated Greensboro, NC 10:10 am-Break f ff ~ f lI \

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SESSION IIt: SEISMIC PROBABILISTIC RISK SESSION tv: SEISMIC PROBABILISTIC RISK ASSESSMENT AND MARGIN STUDI ES-1 ASSESSMENT AND MARGIN STUDIES-2 Chairmen: Chairmen:

Daniel J. Guzy Robert P. Kassawara US. Nuclear Regulatory Commission Electric Power Research Institute Washington, D.C. Palo Alto, CA Robert P. Kassawara Daniel J. Guzy Electric Power Research Institute US. Nuclear Regulatory Commission Palo Alto, CA Washington, D.C.

~1:30.1:50 m ~3:25.3:50 m Recent PRA Applications Recent Extensions to the Seismic Mayasandra K. Ravindra Margin Review Methodology EQE Engineering, Incorporated Robert J. Budnitz Cosa Mesa, CA Future Resources Associates, Incorporated Michael P. Bohn Berkeley, CA Sandia National Laboratories Peter G. Prassinos Albuquerque, NM Lawrence Livermore National Laboratory David L. Moore Livermore, CA El International Incorporated Mayasandra K. Ravindra Kent, WA EQE Engineering, Incorporated Robert C. Murray Costa Mesa, CA Lawrence Livermore National Laboratory ~3:50.4:15 m Livermore, CA Use of Boundary Spectra to Demonstrate

~1:50.2:10 m Seismic Margin at Low Seismicity Sites On Some Aspects of Seismic Fragility Evaluation John D. Stevenson for Diablo Canyon Seismic PRA Stevenson and Associates Robert P. Kennedy Cleveland, OH RPK Structural Mechanics Consulting ~m15.4:40 m Yorba Linda, CA Seismic Evaluation of Large Flat-Bottomed Tanks Bimal E. Sarkar Robert P. Kennedy Bechtel Power Corporation RPK Structural Mechanics Consulting San Francisco, CA Yorba Linda, CA Lloyd S. Cluff Robert P. Kassawara Pacific Gas and Electric Company Electric Power Research Institute San Francisco, CA Palo Alto, CA

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~4:40.5:05 Validation Studies of Seismic PRAs Earthquake Experience Data Relevant Bruce Ellingwood to Nuclear Plant Vertical Storage Tanks Johns Hopkins University Baltimore, MD Philip S. Hashimoto EQE Engineering, Incorporated

~2:30-2:50 m Costa Mesa, CA Component Fragility Study Lessons Learned H. T. Tang Kamal K. Bandyopadhyay, Charles H. Hofma yer, Electric Power Research Institute Mumtaz K. Kassir, and Susan E. Pepper Palo Alto, CA Brookhaven National Laboratory J Lu Woon Tiong

~2:50.3 10 m EQE Engineering Incorporated Costa Mesa, CA Seismic Margin Assessment of Hatch Nuclear Power Plant ~mos-5:30 m Donald P. Moore and Keith Wooten Comparison Studies of HCLPF Capacities Southern Company Services, Incorporated Determined by CDFM and Fragility Analysis Methods Birmingham, AL Robert P. Kassawara Electric Power Research Institute Palo Alto, CA 3:10-3:25 m-Break Robert C. Murray Lawrence Livermore National Laboratory Livermore, CA Robert P. Kennedy RPK Structural Mechanics Consulting Yorba Linda, CA t

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SESSION V: UNRESOLVED SEISMIC ISSUES, 9:25-9:45 am A46 AND RELATED TOPICS-1 An Update of Nine Mile Point SQUG Activities Chairmen: Frances H. Feng and Robert F. Oleck Newton R. Anderson Niagara Mohawk Power Company U.S. Nuclear Regulatory Commission Syracuse, NY Washington, D.C. 9:45 am-Break Neil P. Smith Commonwealth Edison Company Chicago, IL SESSION VI: UNRESOLVED SEISMIC ISSUES, 8:00-8:20 am A46 AND RELATED TOPICS-2 The SQUG Program for Resolution of USI A46- Chairmen:

Status and Implementation Plans Neil P. Smith William R. Schmidt Commonwealth Edison Company MPR Associates, Incorporated Chicago, IL Washington, D.C.

Newton R. Anderson Neil P. Smith US. Nuclear Regulatory Commission Commonwealth Edison Company Washington, D.C.

Chicago, IL 10:00-10:20 am Robert P. Kassawara Electric Power Research Institute SQUG Cable Tray and Conduit Evaluation Procedure Palo Alto, CA Paul D. Smith, Steve J. Eder and Jean. Paul Conoscente Peter I. Yanev EQE Engineering, Incorporated EQE Engineering, Incorporated San Francisco, CA San Francisco, CA 10:20-10:40 am 8:20-8:40 am Guidelines for Estimation Seismic Qualification of Equipment in Operating of Cabinet Dynamic Amplification Plants: Overview and Regulatory Implications K. L. Merz and Paul Ibanez Newton R. Anderson, T. Y. Chang, and ANCO Engineers, Incorporated Ledyard B. (Tad) Marsh Culver City, CA U.S. Nuclear Regulatory Commission 10:40-11:00 am Washington, D.C. Seismic Demand Evaluation Based 8:40-9:05 am on Actual Earthquake Records Overview of SQUG Generic Dilip P. Jhaveri and R. M. Czarnecki Implementation Procedure (GIP) URS Consultants/John A. Blume and Associates Richard G. Starck II San Francisco, CA MPR Associates, Incorporated Robert P. Kassawara and Avtar Singh Washington, DC. Electric Power Research Institute I G. Gary Thomas Palo Alto, CA Stevenson and Associates 11:00-11:20 am Cleveland, OH An Experience Based Procedure 9:05-9:25 am for Estimating Seismic Demand Zion SQUG Pilot Walkdown Miguel A. Manrique, Alejandro Asfura and Gole Mukhim and Resolution of Outliers Impell Corporation Pawan K. Agrawal, Adolf Walser, and Steve R. Bertheau Walnut Creek, CA Sargent and Lundy Chicago, IL Neil P. Smith Commonwealth Edison Chicago, IL

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11:20-11:40 am ~2:10 2:30 m Use of Experience Data for Replacement Simplified Seismic Analysis Methods in France and New Equipment Jacques Betbeder.Matibet and Pierre B. Labbe Harry W. Johnson Electricite de France EQE Engineering, Incorporated Villeurbanne, France Melville, NY

~m30.2:50 m Greg S. Hardy Methods and Requirements for Seismic Design EQE Engineering, Incorporated Costa Mesa, CA in United Kingdom Paul D. Baughman Roy Kunar EQE Engineering, Incorporated BEQE Limited Stratham, NH St. Helens, United Kingdom Charles Smith Nancy G. Horstman EQE Engineering, Incorporated National Nuclear Corporation San Francisco, CA Knutsford, Cheshire, United Kingdom 11:40-1 2:00 ~2:50.3:10 m Testing to Determine Relay Seismic Ruggedness Simplified Seismic Analysis Methods in Japan K. L. Merz Makota Watabe ANCO Engineers, Incorporated Tokyo Metropolitan University Culver City, CA Tokyo, Japan Jess Betlack 3:10-3:25 m-Break MPR Associates, Incorporated Washington, D.C.

M. P. Wade SESSION VIII: SIMPLIFIED SEISMIC ANCO Engineers, Incorporated Culver City, CA ANALYSIS METHODS AND APPLICATIONS TO LOW SEISMICITY SITES-2 Chairmen:

12:00 m-Luncheon Luncheon Speaker Byron Lee, President, NUMARC Peter I. Yanev EQE Engineering, Incorporated San Francisco, CA John D. Stevenson SESSION VII: SIMPLIFIED SEISMIC ANALYSIS Stevenson and Associates METHODS AND APPLICATIONS TO LOW Cleveland, OH SEISMICITY SITES-1 ~m25.3:40 m ChaIrmen: Simplified Seismic Analysis Methods Proposed John D. Stevenson by the International Atomic Energy Agency Stevenson and Associates C. Gordon Duff Cleveland, OH Atomic Energy of Canada, Ltd.

Peter I. Yanev Mississauga, Ontario EQE Engineering, Incorporated San Francisco, CA ~3:40.3:55 m

~4:304:50 m Simplified Seismic Analysis Methods Used Simplified Seismic Analysis Methods by AECL for the Seismic Qualification of CANDU Nuclear Power Plants in the Federal Republic of Germany C. Gordon Duff Maximilian Hintergraeber Atomic Energy of Canada, Ltd.

Siemens AG UB KWU Mississauga, Ontario Erlangen, Federal Republic of Germany

~3:55.4:15 m Guenther Joachim Schauer Technischer Ubervtrachungsverein Load Coefficient Methods Stuttgart, Federal Republic of Germany John D. Stevenson

~1:50-2:40 m Stevenson and Associates Cleveland, OH Use of Simplified Seismic Analysis Methods ln Belgium for Seismic Evaluation of Existing Plants Luc H. Geraets TRACTEBEL Brussels, Belgium

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4~IS-4:35 m ~4:35-5:35 m Consistent Natural Phenomena Design Panel Discussion and Evaluation Guidelines for U.S. Department

Participants:

All the speakers on the topic and of Energy Facilities Goutam Bagchi and Daniel J. Guzy Robert C. Murray U.S. Nuclear Regulatory Commission Lawrence Livermore National Laboratory Washington, D.C.

Livermore, CA Stephen A. Short Impell Corporation Mission Viejo, CA

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SESSION IX: CONSTRUCTION 9:40-10:05 am AND OPERATION ISSUES The Utilization of Commercial Grade Items Chalrmem in Nuclear Safety-Related Applications Warren Bilanin Warren J. Bilanin 4 Electric Power Research Institute Electric Power Research institute Palo Alto, CA Palo Alto, CA S. B. Hager Tom J. Multord Duke Power Company Nuclear Construction Issues Group Charlotte, NC Palo Alto, CA 8:00-8:25 am 10:05 am-Break Visual Welding Inspection and Related Code Issues Randall L. Kurtz SESSION X: PIPING ISSUES-1 Sargent and Lundy Chalrmem 4 Chicago, IL Asadour H. Hadjian 8:25.8:50 am Bechtel Western Power Corporation Los Angeles, CA Configuration Management and Load Monitoring Procedures for Nuclear Plant Structures Gerald C. Slagis Walnut Creek, CA Shih. Lung Chu and Anthony T. Skaczylo Sargent and Lundy 10:20-10:45 am Chicago, IL Improved Load Definitions for Incremental Hinge 8:50.9:15 am Based Nonlinear Piping Analysis Methods" Ken Jaquay Computer Aided Maintenance Rockwell International of Operating Nuclear Stations Canoga Park, CA Harry E. Vanpelt and Kenneth L. Ashe H. T. Tang Duke Power Company Electric Power Research Institute Charlotte, NC Palo Alto, CA 9:15-9:40 am 10:45-11:10 am Design Basis Reconstitution and Configuration Management of Nuclear Power Plants Structures, Dynamic Testing of A Large Scale Piping System Equipment and Piping for Seismic Application with Alternate Pipe Supports Avtar Singh Raul R. Smith Electric Power Research Institute Paul R. Smith, PE. and Associates Palo Alto, CA Boston, MA Wayne J. Merritt 11:10-11r35 am Engineering Planning and Management Incorporated PVRC Damping and Application Benefits Framingham, MA Jerry L. Bitner e JLB Engineering, Incorporated Bethel Park, PA

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I 11:35-12:00 am SESSION X/I: INTEGRATION OF SEISMIC ISSUES '

Piping System Damping Evaluation Chalrmem Asadour H. Hadjian Goutam Bagchi Bechtel Western Power Corporation US. Nuclear Regulatory Commission Los Angeles, CA Washington, D.C.

H. T. Tang Ruble A. Thomas Electric Power Research Institute Southern Company Services Palo Alto, CA Birmingham, AL 12:00 m-Luncheon 3~00.0:30 m Industry Perspective on Resolution of Seismic Issues SESSION XI: PIPING ISSUES-2 Roger Huston Chairmen: Nuclear Management and Resources Council Washington, D.C.

Gerald C. Slagis Walnut Creek, CA J. Carl Stepp Electric Power Research Institute Asadour H. Hadjian Palo Alto, CA Bechtel Western Power Corporation Los Angeles, CA James S. Whitcraft Nuclear Management and Resources Council

~l:30-1:55 m Washington, D.C.

Systems Interaction and II/I Issues ~3:30.4:00 m Steven P. Harris Regulatory Perspective of Seismic Issues EQE Engineering, Incorporated San Francisco, CA Lawrence C. Shao and Robert L. Rothman US. Nuclear Regulatory Commission t

Robert D. Campbell Washington, D.C.

EQE Engineering, Incorporated Costa Mesa, CA ~4:00-4:30 m

~1:55.2:20 m A Criterion for Determining Exceedance Piping Dynamic Reliability of the Operating Basis Earthquake and Code Rule Change Recommendations John W. Reed Jack R. Benjamin and Associates Sam W. Taggart, Jr. and Y. K. Tang Mountain View, CA Electric Power Research Institute Palo Alto, CA Robert P. Kassawara Electric Power Research Institute Daniel J. Guzy Palo Alto, CA US. Nuclear Regulatory Commission Washington, D.C. ~4:30.0:00 m Sam Ranganath Lotung Large-Scale Seismic Experiment General Electric and Soil-Structure Interaction Method Validation San Jose, CA H. T. Tang, Y. K. Tang and J. Carl Stepp

~2:20.2:45 m Electric Power Research Institute Palo Alto, CA Seismic Evaluation of Piping Using Experience Data ~5:00.5:30 m Paul D. Baughman Proposed Modifications of NRC's EQE Engineering, Incorporated Standard Review Plan for Seismic Analysis Stratham, NH Goutam Bagchi, David Jeng and Hans Ashar Mani L. Aggarwal US. Nuclear Regulatory Commission Ontario Hydra Washington, DC.

Toronto, Ontario, Canada Robert D. Campbell EQE Engineering, Incorporated Costa Mesa, CA Steven P. Harris EQE Engineering, Incorporated San Francisco, CA

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Luncheon, Wednesday, December 7, 1988 Thomas Morgan Roberts is a member of the Nuclear Regulatory Commission.

Before assuming his position with the NRC for a second term on July 12, 1985, Commissioner Roberts was Chief Executive Officer and President of Southern Boiler and Tank Works, Inc., of Memphis, Tennessee. Sixteen years with the company provided daily experience in nuclear-component production as well as with codes, standards, and regulations. Mr. Roberts has also been an underwriting member of Lloyd's of London and a director of Boyle Investment Company.

After graduating from Georgia Institute of Technology with a B.S. in Industrial Engineering in 1959, Mr. Roberts was commissioned an ensign in the United States Navy, where he served as engineering officer for three years aboard a destroyer.

Mr. Roberts has served as a member of the Employee Benefits Committee of the National Association of Manufacturers, and was formerly President of the Memphis Symphony and Vice President of the Washington Opera.

THOMAS M. ROBERTS Luncheon, Thursday, December 8, 1988 Byron Lee, Jr. is President and Chief Executive Officer of the Nuclear Management and Resources Council (NUMARC) in Washington, DC.

NUMARC is a new nuclear industry organization whose basic objectives are to draw upon the nuclear power industry's operational and technical knowledge to further enhance excellence and to provide one industry position and line of communication to the Nuclear Regulatory Commission on issues of generic safety and regulatory policy issues.

Before assuming his position with NUMARC in June 1987, Mr. Lee was with Commonwealth Edison for 34 years, where he became Vice President in 1973, C

) Executive Vice President in 1980, and Director of the Board in 1985. Mr. Lee was awarded the James N. Landis Medal from the American Society of Mechanical Engineers in 1983.

A graduate of Purdue University, Mr. Lee received his M.A. degree in Business Administration from the University of Chicago. He was honored by Purdue as a "Distinguished Engineering Alumnus" in 1970.

BYRON LEE

ACCOMMODATIONS AIRLINE DISCOUNT REGISTRATION The Symposium will be held at Delta Airlines, in cooperation with The registration fee covers the the Hilton Hotel at Walt Disney EPRI, is offering special fares which cost of symposium materials, World Village in Orlando, Florida. afford a 5% discount off Delta's published proceedings, continenta The hotel, located 25 miles from published round trip fares, or 40% breakfasts, luncheons, coffee Orlando International Airport, is on off Delta's unrestricted round trip breaks, the receptions and dinner.

Disney World property just a short, coach fares within the United States. To register, please complete and complimentary shuttle ride from Seven days advance reservations return the registration form with a both Disney World's Magic and ticketing are required. check (payable to Conferences and Kingdom and Epcot Center. To take advantage of these Travel) to M. Lenihan at EPRI. Credit The hotel features two outdoor discounts, follow these simple steps: cards are not accepted; no refunds swimming pools, a health club and will be issued for cancellations

1. Call Delta at 1-800-221-1212 (8:00 two lighted tennis courts. Golf is received after November 30, 1988; am to 8:00 pm, Eastern time, and company checks mailed available on three Disney World daily) separately from the registration form championship courses nearby.
2. Refer to Special Meetings should indicate symposium and Should Symposium attendees Network File Number Q10278 attendee names.

choose to extend their visit to enjoy

3. These discounts are available the,surroundirig attractions, our guaranteed group rate at the hotel only through Delta's toll-free of $ 99 (single or double) is available number for travel between from Saturday, December 3 through December 4-12, 1988.

Ddando Sunday, December 11.i To ensure your accommodations, you must make your reservation by Corneneion nr Cenier 5 November 13, 1988, referring to Mrsde ~

the EPRI symposium. lnsernarional

~ Sea WorM Hilton at Walt Disney World Village HIIT~

rn 1751 Hotel Plaza Boulevard + Ytrssrmmee J

Lake Buena Vista, Florida 32830 Miami Phone: 407/827-4000 Gardens i Telex: 52-3274 Questions regarding registration, fees, hotel accommodations or other non-technica/ aspects of the symposium should be addressed to:

Maureen Lenlhan Conference Coordinator Electric Power Research Institute 3412 Hillview Avenue Palo Alto, CA 94304 415/855-2127 Telex 82977 ~ FAX 415/855-2954 For general technical questions contact:

J. Carl Stepp Manager, Seismic Center Electric Power Research Institute 3412 Hillview Avenue Palo Alto, CA 94304 415/855-2103

SYMPOSIUM STEERING COMMITTEE Chairman Ajaya K. Gupta Professor of CivilEngineering North Carolina State University'aleigh, North Carolina Members Ted B. Belytschko Robert P. Kennedy Professor of Civil Engineering RPK Stru'ctural Mechanics Consulting, inc.

Northwestern University Yorba Linda, California Evanston, illinois Robert C. Murray Robert Bosnak Associate Program Leader Deputy Director, Division ol Engineering Reactor Safety Oflice of Research Lawrence Livermore National Laboralory California US. Nuclear Regulatory Commission Livermore, California Washington, DC M.K. (Ravl) Ravlndra Jerry N. Burford Vice President, EQE Engineering, fnc Section Supervisor, Nuclear Licensing Costa Mesa, Florida Power and Light Company Juno Beach, Florida James Richardson Assistant Director for Engineering Shih-Lung (Pete) Chu Ollice of Nuclear Reactor Regulation Associate and Head US. Nuclear Regulatory Commission Structural Analytical Division Washington, D.C Sargent and Lundy Chicago, illinois J. Carl Stepp Manager, Seismic Center S.B. (Pete) Hager Electric Power Research Institute Chief Engineer, Civil Environmental Division Palo Alto, California Duke Power Company Charlotte, North Carolina John D. Stevenson Stevenson and Associates Robert P. Kassawara Cleveland, Ohio Program Manager, Safety Technology Electric Power Research Institute Peter I. Yanev Palo Alto, California Chairman, EQE Engineering, Inc San Francisco, California

REGISTRATION CURRENT ISSUES RELATED TO NUCLEAR POWER PLANT STRUCTURES, EQUIPMENT AND PIPING Please register me for the Second Symposium on Current Issues Related to Nuclear Power Plant Structures, Equipment and Piping with Emphasis on Resolution of Seismic Issues 'ni-Low Seismicity Regions, December 7-9, 1988.

(please print)

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Received by Received after Nov. 21, 1988 Nov. 21, 1988 0 EPRI member utilities $ 200 $ 225 0 U.S. Government or U.S. university $ 200 $ 225 0 Non-member utilities $ 500 $ 525 0 All other organizations $ 500 $ 525 This registration form, accompanied by your check(payable to Conferences and Travel) should be returned to:

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Please note: lf you must process a company check, mail your registra-tion form now and when the checkis forwarded, enclose a copy of the form; or at the very least, have your name on the check stub so that you receive credit for payment.

PROBABILISTIC SEISMIC HAZARD RESULTS FOR SITES IN A REGION OF LOW SEISMICITY Samir G. Khoury and Umesh Chandra Ebasco Services Inc.

2211 W. Meadowview Rd.

Greensboro, N.C. 27407 The methodology for seismic hazard evaluation developed by the Electric Power Research Institute (EPRI) was applied to two nuclear power plant sites, St. Lucie and Turkey Point, located in the Florida Peninsula, a region of low-seismicity. The seismic source zones and the seismicity parameters established by each of six technical evaluation contractors (TEC) for the Eastern U.S., and the seismic source zones and seismicity parameters determined by Ebasco Services Incorporated for the Northern Caribbean were used in the computations. The seismic hazard values thus calculated for each of these models were then aggregated in accordance with the EPRI recommended procedure to generate the Qnal hazard curves.

The results of these evaluations indicate that the hazard is very low for the two sites. The 50th percentile annual probability of exceeding 0,10g is 1.27E-S for St. Lucie and 1.05E-5 for the Turkey Point site. These values are significantly lower than 2,5EC used as input in the "Shutdown Decay Heat Removal Analysis" computations for the two plants (> g). Also, median hazards computed for the St. Lucie and Turkey Point sites fall well below the hazard computed at the SSE for various nuclear power plant sites in the eastern United States: 1,0E-3 to 4.0E-5, EPRI; and 2.0E-3 to 7.0E-S, LLNL(3).

The Seismic Safety Margins Research Program (SSMRP) was established to develop models that predict the probability of core damage and radioactivity release in nuclear power plants from seismic initiating events. The results of seismic analyses for several plants in the eastern United States indicate that the dominant contribution to core damage is likely to occur from earthquakes-causing peak ground acceleration at. the site in the range of 02 to 0.4g, and generally greater than 03g. The 50th percentile annual probability of exceeding 03g at St.

Lucie is 132'nd at Turkey Point is 7.70E-7. The mean. core damage f'requencies at the two plant sites, computed by using these probabilities, are well below 1.0E-S per reactor year, an estimate consistent with the U.S, Nuclear Regulatory Commission safety objective.

INTRODUCTION Deterministic methods of seismic risk evaluation are suitable in tectonically active areas, for example, where seismogenic structures can be identified and fault length-magnitude relations applied. In areas of low seismicity, the use of deterministic methods do not lead to satisfactory results and some understanding of the frequency of occurrence of earthquakes for various levels of magnitude is essential. Since the deterministic procedure ignores the frequency of occurrence of earthquakes, probabilistic methods complement the hazard estimates in an important manner. Probabilistic methods also provide an interesting and, usually robust, comparison about the relative level of seismic hazard among different sites.

As a result of the unresolved questions regarding the cause and source of seismicity in the region of the United States east of 105 W longitude (Eastern U.S.), the U.S. Nuclear Regulatory Commission (bfRC) has been actively pursuing the use of probabilistic methods, as alternatives to the deterministic approach used in the past, for re-evaluation of the seismic design of nuclear facilities .n the eastern United States. This re-evaluation takes into account the uncertainties in source geometry, seismicity parameters and ground motion for the large earthquakes that occur in the Eastern U.S. As part of the NRC-funded investigations, the Lawrence Livermore National Laboratory (LLNL) (4) conducted probabilistic seismic hazard evaluations for ten "sample sites". A parallel probabilistic seismic hazard study, based on an intensive data collection and evaluation effort, was implemented by the Electric Power Research Institute (EPRI) (g g 2, 5, 9, JQ, 11, U, Q, 14) with the assistance of six Technical Evaluation Contractors (TEC). Both the NRC funded LLNLstudies, and the EPRI investigations; funded by a group of nuclear power plant owners in the Eastern U.S., utilize comprehensive seismic and tectonic data bases and recent advances in the probabilistic methodologies for the evaluation of seismic hazard for sites located in the Eastern U.S.

In this study we apply the methodology developed by the EPRI to estimate seismic hazard at two nuclear power plant sites located in the Florida Peninsula, a region of low seismicity.

METHODOLOGY

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v The general theory of probabilistic seismic hazard analysis was developed by Cornell j2) and Cornell and Merz (Q). A FOR'IRAN Computer program for seismic risk analysis based on this theory was published by McGuire (+) as the USGS Open-File Report 7647.

The details of the EPRI methodology are presented by McGuire and Stepp in these proceedings. BrieQy, the software package, EQHAZARD, developed by the EPRI (Q g) differs from McGuire (39) in that it allows for the incorporation of multiple hypotheses and associated probabilities for the ground motion model, ntaximum magnitude for each source zone, and seismicity parameters for each source zone. With multiple hypotheses, the number of possible source combinations becomes very large. The software package is so designed as to minimize computation time, form various possible combinations, and extract constant percentile hazard curves at specified percentile levels. The procedure allows for expressions of uncertainty in input to hazard computations, and analysis of sensitivity of various source and attenuation parameters to the hazard. The procedure also allows for the spatial variation of the rate of seismicity within a source zone.

The input parameters (source geometries, maximum magnitudes, seismicity parameters, and associated probabilities) for seismic hazard computation were developed independently by six technical evaluation contractors (TEC) (g $7, ih tt19). These parameters along with

appropriate ground motion models (attenuation relations) form the basis for the seismic hazard computation using the EPRI methodology.

INPUT DATA The methodology developed by the EPRI for the computation of seismic hazard was applied to two nuclear power plant sites located in the Florida Peninsula (Figure 1).

The three different attenuation relations discussed in the EPRI Applications Manual (8, Section

6) were used, with equal weights, in the hazard calculations. These are: i) semi-theoretical model of Nuttli (M), which utilizes a theoretical scaling model and low magnitude earthquake recordings from the Central United States, ii) an empirical method that uses ground motion data from the central and eastern United States, and data from California (~), and iii) a random vibration method which utilizes source scaling model, a random-process representation of acceleration, and a simpliGed representation of propagation effects (>).

For the computation of hazard at the two sites, the source containing the sites, the source or source combinations adjacent to the one containing the sites, Charleston area'sources, and New Madrid sources were considered appropriate. Also it was noted that some of the Caribbean sources of high seismicity were closer to the sites than the Charleston or New Madrid sources.

This was especially true for the Turkey Point site. Consequently, we investigated the tectonics of the Northern Caribbean region in order to delineate seismic source zones and develop associated seismicity parameters for that region (~). These data were then used to evaluate the hazard at the sites from earthquakes in the Northern Caribbean.

The maximum magnitude distribution and seismicity parameter distribution (referred to as smoothing options in the EPRI reports) for each source zone for each of the six Technical Evaluation Contractors were taken f'rom the report prepared by that contractor. For each source zone a focal depth of 10 km for the occurrence of earthquakes was assumed. The lower bound magnitude of integration was taken to be 5. It was thus assumed that earthquakes of magnitude smaller than 5 will not have any damaging effect on the plant structure or components.

HAZARDCOMPUTATION Using the EPRI software. package, seismic hazards were computed for the St. Lucie and Turkey Point sites using the seismic source zones and seismicity parameters established by each of the six EPRI Technical Evaluation Contractors (TEC), and the seismic source zones and seismicity parameters identiGed by Ebasco Services Incorporated for the Northern Caribbean. The location and',"extent of the seismic source zones that were evaluated in this study are shown on Figures 2 through 8. The source zones that contributed more than 1.0E-10 to the seismic hazard'at each of the two plant sites have also been listed on these Ggures. The TEC source zone names, labels, and the EPRI Data Base Manager code numbers are given in Table l.. Two of the Northern Caribbean sources, Cayman Trough and Jamaica-Western Hispaniola, contributed to the seismic hazard at Turkey Point, but none contributed to the hazard at St. Lucie. Also contributions of New Madrid area sources to the seismic hazard at both plant sites for each of the six TECs were negligible. The scenarios and weights for the source zones that contributed to seismic hazard are given in Table 2. The seismic hazard values that were calculated from each TEC model were then aggregated in accordance with the EPRI recommended procedure the final hazard curves. to'enerate

RESULTS Seismic hazard results for the St. Lucie and Turkey Point sites, computed in terms of annual probability of exceedance for different values of peak ground acceleration, are shown on Figures9 and 10, respectively. The results are presented as constant percentile hazard curves. The 15th, 50th, and 85th percentile, curves represent the equally weighted aggregated results of all six TECs. The 50th percentile hazard curve of each TEC prior to aggregation is also shown on Figures 9 and 10.

It is observed that the hazard curves of St. Lucie for Bechtel, Rondout Associates and Weston Geophysical are very close to each other, and to the aggregated 50th percentile hazard curve for all TECs. The hazard curve for Dames and Moore is also close, although it shows a somewhat smaller annual probability of exceedance. At the two extremes are the hazard curves derived from the input data for Law Engineering (lowest hazard) and Woodward Clyde Consultants (highest hazard).

The hazard curves of Turkey Point for Bechtel, Rondout Associates, Weston Geophysical and Woodward Clyde Consultants teams are very close to each other, and to the aggregated 50th percentile hazard curve for all TECs. The hazard curve for Dames and Moore team is also close, although it shows a somewhat smaller hazard. The hazard curve derived from the input data for Law Engineering team yields the lowest hazard result.

As shown on Figure 9, the peak ground acceleration (PGA) seismic hazard calculated for the St. Lucie site is very low. The annual probability of exceeding 0.10g is 1.27E-S. The seismic hazard calculated for the Turkey Point site, Figure 10, is even lower. The annual probability:

of exceeding 0.10g is 1.05E-S.

Finally, it should be noted that the application of the EPRI methodology to evaluate seismic hazard at the St. Lucie and Turkey Point sites provides a conservative estimate. Generalized assumptions that may be valid for most of the eastern United States were also applied by some of the Technical Evaluation Contractors to Florida Peninsula by default. For example, one of the TEC teams, Woodward Clyde Consultants, specified the use of the following maximum magnitudes (and associated probabilities) for background sources along the entire East Coast:

5.8 (033), 6,2 (034), and 6.6 (033). Although these values may be appropriate for other regions along the East Coast, they do constitute overestimates of seismic conditions in Florida Peninsula. The sites are located in a region of very low seismicity. Figure 1 shows a map of maximum Modified Mercalli (MM) intensity experienced at sites in Florida f'rom historical earthquakes, 1780-1980 (+). Lane (~ stated that of the earthquakes felt in Florida, 'only six could be considered to have had epicenters in Florida It is possible that the shaking in some of these earlier events were caused by distant earthquak'es outside Florida. Shaking and rumblings assochted with some other natural (such as collapse of a sink hole) or man-made phenomena (such, as explosion caused by mining or construction activity, or during military exercises) may=be mistaken for earthquakes. The seismic origin of a shock felt in 1930 in Everglades, La"Belle, and Ft. Myers, has been questioned and blasting is suspected. Similarly, generalized assumptions made by other TECs can also be questioned for conservative estimates of seismicity in Florida This is especially important because'ost of the contribution to the St. Lucie and Turkey Point sites, in the case of each of the TEC source zones, is derived from the background source containing the sites.

Of the three ground motion models considered, the random vibration model yields lowest hazard results. This is illustrated on Figures 11 and 12, showing sensitivity of results to different attenuation relations by plotting 50th percentile hazard curves. The random

vibration model for ground motion prediction appears to be gaining greater acceptance in the scientiQc community. For example, Savy (~) noted that a large weight, in the LLNL study, is now assigned to the class of "random vibration" models (RV-models). If this model is considered more representative of conditions in eastern North America, then the hazard computed using all three attenuations (Nuttli, 1984; Empirical Model; and random vibration model) should be considered a conservative estimate.

DISCUSSIONS The seismic events of interest in the evaluation of external hazards to nuclear power plants are those that are accompanied by ground motions of sufQciently large amplitudes and duration to initiate accident scenarios that would result in the release of radioactive material from a damaged reactor'core. Therefore, it is important to develop evaluation criteria to discriminate between significant and inconsequential levels of seismic risk.

The guidance provided by the NRC in their Safety Goal Policy Statement requires a licensee to "provide reasonable assurance, giving consideration to the uncertainties involved, that a core-damage accident will not occur at a U,S. nuclear power plant". Based. on an evaluation of the total population'of nuclear power plants operating in the U.S. it was suggested that this objective can be met if individual plants have mean core damage frequencies in the range of about 1.0E-5 or less per reactor year ($). This numerical estimate was presented as a trial value which was used to estimate whether or not the risk from seismically initiated accidents is an important contributor to the overall risk at six nuclear power plant test sites..

The Seismic Safety Margins Research Program (SSMRP) studies indicate that the dominant earthquake generated peak ground acceleration range for seismic core damage is between 0.2-0.4g. The Probabilistic Risk Assessment (PRA) studies sponsored by the utilities, and performed between 1981 and 1985, show that the dominant acceleration level that lead to seismic core damage is generally greater than 03g. The studies of Decay Heat Removal Requirements at nuclear power plants (TAP AC5, +) conclude that the dominant contribution to core damage is from accelerations in the range of 02-0.4g The seismic risk assessment performed under Task Action Plan APS, to evaluate the Decay Heat Removal Requirements of six nuclear power plants, adopted the value of 25EP as the annual probability of exceeding 0.10g at St. Lucie and 0.06g at Turkey Point nuclear power plant sites (1, P). The slopes of the probabilistic seismic hazard curves at higher acceleration levels for the two plant sites were derived from hazard curves developed by LLNL for Vogtle, Georgia and River Bend, Louisiana sites. The curve coordinates for St. Lucie and Turkey Point were obtained by shifting the curves of Vogtle and River Bend sites vertically downward so that the values at 0.10g for St. Lucie and 0.06g for Turkey Point were Qxed at 2.5EQ per year.

From these 'curves, the probability of having an earthquake at St. Lucie with a peak ground acceleration, of 030g was estimated at 1.9E-5; while the probability of an earthquake at Turkey Point with a"peak ground acceleration of 030g was estimated at 52'nominal) and 8.0E-6 (corrected for local site conditions). Based on these assumptions, the TAP A45 studies concluded that the seismic core damage frequency (point es'timate) per year was 13E-5 for St.

Lucie and 1.0E-5 for Turkey Point, matching closely the target value of 1.0E-5 per reactor year suggested in the report NUREG/CR-5042 ($) for meeting the NRC safety objective.

However, the site speciQc annual probabilities of exceeding 0.10g at St. Lucie and Turkey Point are signiQcantly lower than 23EQ. The probability of exceeding 0.10g is 1.27E-S for St.

Lucie and 1.05E-S for Turkey Point, while the probability that the peak ground accelerations

will exceed 03g is 132E-6 for St. Lucie and 7.70E-7 (nominal) for Turkey Point. Using these values, that are an order of magnitude lower than those used'in the TAP AAS studies, to compute a mean seismic core damage frequency for the two plants will result in values that are well below the target value of 1.0E-S suggested by NUREG/CR-5042 ()) as a lower bound estimate, below which seismic hazard should be of little concern.

CONCLUSION Both the St. Lucie and Turkey Point sites are located in a region which is considered seismically benign (J, Q). In fact, both sites are located in the lowest U.S. seismic risk zone, one of no damage (2Z). In confirmation, the probabilistic seismic hazard results for the two plant sites are also very low. It would be appropriate that sites that have such low seismic hazard be classed Below Regulatory Concern (BRC).

ACKNOWLEDGMENTS This study was supported by the Florida Power and Light Company.

REFERENCES

1. W, R. Cramond, D. M. Ericson, Jr. and G. A. Sanders. "Shutdown Decay Heat Removal Analysis of a Combustion Engineering 2-Loop Pressurized Water Reactor." August 1987, U.S. Nuclear Regulatory Commission, NUREG/CRQ710, SAND86-1797.
2. G. A. Sanders, D. M. Ericson, Jr. and W. R. Cramond. "Shutdown Decay Heat Removal Analysis of a Westinghouse 3-Loop Pressurized Water Reactor." March 1987, U.S. Nuclear Regulatory Commission, NUREG/CRP762, SAND86-2377.
3. P. G. Prassinos. "Evaluation of External Hazards to Nuclear Power Plants in the United States." April 1988, U.S. Nuclear Regulatory Commission, NUREG/CR-5042, UCID-21223, Supplement 1, p. 53,
4. D. LG Berneuter, J. B. Savy, R. W. Mensing, J. C. Chen and B. C. Davis. "Seismic Hazard Characterization of the Eastern United States: vol. 1, Methodology and Results for Ten Sites." April, 1985, Lawrence Livermore National Laboratory, UCID-20421.
5. H V

. Palo Alto, CA: Electric Power Research Institute, EPRI NP4726, July 1986.

6. V Palo Alto, CA: Electric Power Research Institute, EPRI NPG4726-CCMP, April 1987.
7. V JVfggggl. Palo Alto, CA: Electric Power Research Institute, EPRI NP<726-CCMP, March 1987.

V 4 Palo Alto, CA: Electric Power Research Institute, EPRI NP<726, March 1987.

9. '

W* G* " iM C CA:

Research Institute, EPRI NP4726, July 1986.

10. V by Dames and Moore, Palo Alto, CA: Electric Power Research Institute, EPRI NP4726, July 1986.

byl g'*'P*'ECp,PI Research'Institute, EPRI NP4726, July 1986.

AI,CA:El*

V V

12.

b Gld C~ P AE.CA:

Institute, EPRI NP4726, July 1986.

13. '

V b ~ *b* G p, ~ AI,CA: El EPRI NPP726, July 1986.

14.

l EPRI NP-4726, July 1986.

l, I,CA: El '*P V l R** El

15. C. A. Cornell. "Engineering Seismic Risk Analysis." Bull. Seism. Soc. Am., vol. 58, 1968, pp. 1583-1606.
16. C. A. Cornell.

Wv "Probabilistic C. Taylor, 1971, Wiley Interscience.

Analysis of Damage to Structures under Seismic Loads." In Chapter 27, edited by D. A. Howells, I. P. Haigh, and

17. C. A. CornelL Cambridge, Massachusetts, 1974, p. 110.
18. C. A. Cornell and H. A. Merz. "Seismic Risk Analysis of Boston." Journ. Struc. Div.,

Proceedings of Am. Soc. Civil Engineers, vol. 101, No. ST10, pp, 2027-2043.

19. R. K. McGuire. "FORTRAN Computer Program for Seismic Risk 'Analysis.", U.S.

Geological Survey Open-File Report 76-67, 1976, p. 99.

20. O. W. Nuttli. Letter to Dr. Dae H. Chung, Appendix C-A in "Seismic Hazard Characterization of the Eastern United States: Methodology and Interim Results for Ten Sites." by D. L Bernreuter et al., NUREG/CR-3756, 1984, pp. C-99 to C-105.
21. R. K. McGuire. "Methods of Earthquake Ground Motion Estimation for the Eastern United States.", Electric Power Research Institute research project No. RP2556-16, prepared by Risk Engineering Inc., March 1986.
22. w P Greensboro, NC: Ebasco Services Incorporated, January 1988.
23. G. Reagor and C. W. Stover. "Updated earthquake catalogue for the states of Florida and Georgia" U.S.Geological Survey Open-File Report 83423, 1983, p. 17.
24. E. Lane. "Earthquakes and seismic history of Florida" Information Circular No. 93, Bureau of Geology, Division of Resource Management, Florida Department of Natural Resources, Tallahassee, 1983, p. 8.
25. J. B. Savy. "Seismic Hazard at 69 Sites in the Eastern U.S. based on Expert Opinion Regional Comparison." Seismological Research Letters, abstract, vol. 59, 1988, p. 14.
26. U.S. Nuclear-Regulatory Commission, Task Action Program A<5.
27. by International Conference of Building OfQcials, Whittier, California, 1985, p. 817.

87 86 85 84 83 82 81 80 A ABAMA 31 30 29 L J J F LQRJQ 28 CUI F OF MBXlCO

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27 C Luci EXPLAH TION 26 Tv&aY 25 T T I 1 1~%

Figure 1.":.Location of St. Lucie and Turkey Point nuclear power plant sites. The map also shows maximum Modified Mercalli (MM) intensity experienced at sites in Florida from historical earthquakes, 1780-1980. Intensities ore given in arabic numerals.

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>>gure 6. Seismic source zones derived from the tectonic interpretations by Weston Geophysical Corporation, and used in the hazard computation for the St. Lucie and Turkey Point sites

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2 CB002 Jamaica-Western Hispaniola None 2 3 CB003 Eastern Hispaniola 4 CB004 Puerto Alco Trench 5 CB005 Muertos Trench 6 CB006 Greater Antilles- Lesser Antilles Transition Figure 8. Seismic source zones in the northern Caribbean developed by Ebasco Services Incorporated from tectonic interpretations, and used in the hazard computation for the St. Lucie and Turkey Point sites

HAZARD RESULTS AT ST. LUCIE ALL EXPERT TEAMS 10

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HAZARD RESULTS AT TURKEY POINT ALL EXPERT TEAMS 10

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, ercentile hazard curves (solid lines) when equally weighted hazard results for all echnical Evaluation Contractors were aggregated.

HAZARD RESULTS AT ST. LUCIE SENSITIVITY TO DIFFERENT ATTENUATION RELATIONS 10 a Nuttli (19S4) Attenuation Empirical Attenuation Random-Vibration Attenuation All Attenuation Combined

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< 10 10 0 'I 00 200 300 400 500 ACCELERATION (cm/sec )

Figure 11. Sensitivity of hazard results (50th percentile) at St. Lucie for different attenuation relations

HAZARD RESULTS AT TURKEY POINT SENSITIVITY TO DIFFERENT ATTENUATION RELATIONS 10 o Nuttli (1984) Attenuation Empirical Attenua tion 10 Random-Vibration Attenuation All Attenuation Combined 10

<C C)

IJJ 4J 10 X

bJ

-5 CQ

<C CO C)

-6 10 10 10 0 200 300 400 500 ACCELERATION (cm/sec )

Figure 12. Sensitivity of hazard results (50th percentile) at Turkey Point for different

,'ttenuation relations

Table 1 Computerized Data Base Label No. of Source Zones TEC Name TEC Label No. Source Name Data Base Label No.

(Used on TEC Maps) (Used on Computer Files)

Bechtel Group 13 Mesozoic Basins 01300 30 New Madrid 03000 31 Reelfoot Rift 03100 H Charleston Area 05200 N-3 Charleston Faults 05900 BZ-O, New Madrid Region 00100 BZ-1 Gulf Coast Background 00600 BZ-4 Atlantic Coast Background 02000 Dames 6 Moore 20 Southern Coastal Margin 02000 21 New Madrid 02100 22 Reelfoot Rift 02200 22-21B Reelfoot Rift-New Madrid 91500 52 Charleston Rift 05200 53 Southern Appalachian Default 05300 54 Charleston Seismic Zone 05400 65 Dunbarton Triassic Basin 06200 Law Engineering 04a Reelfoot Rift(A) 00401 04b Reelfoot Rift(B) 00402 08 Mesozoic Basins 00816 18 Reelfoot Rift Faults 01800 35 Charleston 03500 108 Brunswick Background 04300 126 Southern Coastal Block 06001 M-37 Mafic Pluton 03837 M-38 Mafic Pluton 03838 M-39 Mafic Pluton 03839 M-40 Mafic Pluton 03840 M-41 Mafic Pluton 03841 M-42 Mafic Pluton 03842 M-43 Mafic Pluton '03843 M-44 Mafic Pluton 03844 M-45 Mafic Pluton 03845 M-48 Mafic Pluton 03848 M-49 Mafic Pluton 03849 M-50 Mafic Pluton 03850 Table 1 - continued

Table 1 (Continued)

Computerized Data Base Label No. of Source Zones TEC Name TEC Label No. Source Name Data Base Label No.

(Used on TEC Maps) (Used on Computer Files)

Rondout Associates 1 New Madrid 00100 2 New Madrid Rift 00200 24 Charleston 02400 26 South Carolina 02600 49-05 Basement

'ppalachian 04905

Background

51 Gulf Coast to Bahamas 05100

Background

Weston Geophysical 25 Charleston 02500

'26 South Carolina 02600 31 New Madrid 03100 32 Reelfoot Rift 03200 104 Southern Coastal Plain 05400

Background

107 Gulf Coast Background 05700 2032-2031 Combination (C-11) 91100 Z104-2022 Combination (C-20) 92000 Z104-Z025 Combination (C-21) 92100 Z104-Z026 Combination (C-22) 92200 Z104-2022, Combination (C-23) 92300

-Z026 Z104-2022 Combination (C-24) 92400

-Z025 Z104-Z028BCDE Combination (C-27) 92700

-2022

-Z025 Z104-Z028BCDE Combination (C-28) 92800

-Z022

-Z026 Woodward-Clyde 1 Continental Shelf Edge 00100 29 South Carolina Option 1 02900 29A1 South Carolina Option 2 02901 29A2 South Carolina Option 2 02902 29B South Carolina Option 3 02903 30 Charleston NOTA 03000 40 Central Reelfoot Rift 04000 41 Combination (C-8) 90800 44 New Madrid Loading Zone 04400

TABLE 2 Scenarios for Contributing Source Zones St. Lucie Bechtel 00600 + 02000 + 01300 + 05200 0.05 00600 + 02000 + 01300 0.05 00600 + 02000 + 05200 0.45 00600 + 02000 0.45 Background 00600 1.0 02000 1.0 Dames and Moore 02000 + 05400 0.196 02000 + 05400 + 05200 0.322 02000 + 05400 + 05300 0.182 02000 + 0540D 0.084 02000 + 0540D + 05200 0.138 02000 + 0540D + 05300 0.078 Background 02000 1.0 Law Engineering 04300 + 06001 + 02200 0.27 04300 + 06001 + 00816 0.27 04300 + 06001 0.46 Background 04300 0.42 06001 0.49 Rondout 02400 + 02600 + 04905 + 05100 1.0 Associates Background 04905 1.0

~ 05100 1.0 Weston Geophysical 05700 + 92000 0.001 Corporation 05700 + 02500 + 92100 0.012 05700 + 02600 + 92200 0.069 05700 + 02600 + 92300 0.312 05700 + 02500 + 92400 0.368 05700 + 02500 + 92700 0.126 05700 + 02600 + 92800 0.100 05700 + 05400 0.012 Background 05700 1.0 Woodward Clyde WCCBK 0.468 Consultants WCCBK + 02903 0.105 WCCBK + 02900 0.122 WCCBK + 02901 + 02902 0.305 Background WCCBK 1.0

TABLE 2 (continued)

Scenarios for Contributing Source Zones Turkey. Point

~~eaaB ~e~o2 ~We ~t3 Bechtel 00600 + 02000 + CB001 + CB002 1.0 Background 00600 1.0 02000 1.0 Dames and Moore 02000 + CB001 + CB002 1.0 Law Engineering 04300 + 06001 + 02200 + CB001 + CB002 0.27 04300 + 06001 + 00816 + CB001 + CB002 0.27 04300 + 06001 + CB001 + CB002 0.46 Background 04300 0.42 06001 0.49 Rondout 04905 + 05100 + CB001 + CB002 1.0 Associates Background 04905 1.0 05100 1.0 Weston Geophysical 05700 + CB001 + CB002 1.0 Corporation Background 05700 1.0 Woodward Clyde WCCBK + CB001 + CB002 1.0 Consultants Background WCCBK 1.0 Notes: Source Zone numbers correspond to those on Table 4-1 and on Figures 2 through 7.

Each TEC scenario is made up of the allowable source zone combinations whose total weights, or probability of activity add up to 1.0.

Weight is defined as the fractional probability of activity.

HISTORY OF SEISMOLOGICAL ACTIVITY IN FLORIDA:

EVIDENCE OF A UNIQUELY STABLE BASEMENT r

Douglas L. Smith and Anthony F. Randazzo Department of Geology University of Florida Gainesville, FL 32611 ABSTRACT The historical paucity of well-documented seismic events in Florida during the past three centuries has been attributed,, in part, to the lack of local or regional recording equipment and to the sparse abundance and uneven distribution of the early population. Approximately a dozen low intensity events can be described for Florida since 1727, A.D. However, an approximate epicenter assignment can accompany only the three events reported in the last 35 years.

The most recently felt tremor in Florida (December, 1975, Daytona) was assigned an estimated magnitude of 2.9 mbLg; no magnitudes are known for earlier events.

Observations since 1978 at GAI in Gainesville, a single, vertical component, short-period station, have yielded no evidence of events within the state.

The general aseismicity of Florida is consistent with recently-developed concepts of the nature of the Florida basement. Based on drill-core analyses and geophysical investigations, the Florida basement is characterized by a Cambrian granitic batholithic complex and an undistorted overlying cover of early Paleozoic sedimentary rocks in the north and an early Mesozoic volcanic rock province in the south. Reconstructions of tectonic history place Florida and other parts of the Gulf Coast margin within a leading edge of a seismically active Paleozoic Africa-South America landmass which converged with North America to form Pangea. Rifting of this supercontinent began during the Triassic Period (approximately 200 million years ago), eventually producing the present continental configuration.

The Florida peninsula, constrained by rifting geometries, remained appended to North America and, today, represents the undynamic, tectonically stable, outboard trailing edge of a divergent plate margin. Accordingly, the Florida basement is geologically and tectonically distinct from the Appalachian and other crustal trends of the southeastern United States. Supracrustal rocks (Cenozoic sedimentary rocks covering the basement) further substantiate the lack of tectonic activity of the Florida peninsula. These carbonate/sand units are essentially undeformed structurally, indicating stable tectonic conditions for at least the past 65 million years.

Portrayals of seismicity source conditions for the eastern United States are not necessarily applicable for Florida. The distinctly different basement rocks and tectonic history of Florida provide a compelling explanation for aseismicity in this geographic region today.

INTRODUCTION In his popular introductory text on seismology, Richter (1958) ~rote:

"Earthquakes are exciting and sometimes spectacular events, offering opportunity for mistakes and exaggeration. ...the serious student needs knowledge both of earthquakes and of the psychology of error." The study of seismology of the Florida peninsular epitomizes the applicability of Richter's statements.

Distinguished by a paucity of indisputable seismic events and by an initially sparse and unevenly distributed population, peninsular Florida has yet to experience any events sufficiently well-documented to permit a characterization of the state beyond "aseismic."

Although limited, a list of earthquakes can be assembled for Florida. This report seeks not only to present a history of reported seismological activity in Florida, but also to depict the basement geology and tectonic history to be as distinct as the seismicity with respect to adjacent terranes. The tectonic stability of .the Florida Plateau, as evidenced by its seismic history, contributed to the concept of its separate geologic origin, chronologically and spatially removed from North America and physically rooted in an older, uniquely quiescent lithospheric fragment..

EARTHQUAKES IN FLORIDA The earliest attempt to compile a record of earthquakes in Florida (Campbell, 1943) was based largely on reviews of weather bureau records, private files, and early newspaper accounts. Fifteen dates, beginning in 1727, are cited for tremors, and Rossi-Forel intensities were assigned to approximately half of the events. Most of the reports, however, are characterized by vague locations, conflicting times, and apparent confusion with events outside the state. For example, reports of shocks on 31 Aug 1886 in north Florida are surely attributable to the well-known event in Charleston, S.C., on that date, and a disturbance felt in Key West on 22 Jan 1880 would have been the disastrous

table 1. Listing of reported earthquakes in florida. Data from Campbel( (19843), bott (1983) and Reagor e't al. (1987). All locations (except 27 Oct 1973 event) are estimates. Intensity values ara from the modified Hercalli scale; "f" indicates insufficient information to assign value.

Date ~tttt Utt t. t t. tt. t ttL ~tt tt Comnents

'1727 Oct 12 "Severe" tremors felts in St. Augustine. Reported as 29 Oct by Campbe(I (1945) 1780 feb 6 30 A 87,2 Vl Hott (1983) reports this event for 8 Nay 17S1, and a mild tremor for this date. Description suggestive of hurricane.

1879 Jan 13 0445 29.5 82.0 Vl 'uo shocks of 30 sec duration. felt throughout north florida and south Georgia.

0445 29.5 82.0 1M6 Jan 8 30A 81.7 1886 Sep 1 30.4 81.7 IV Identical reports for 3, 4, 5, 8, 9 Sep; All aftershocks of Charleston, S.C., event.

1S93 Jm 21 0707 30A 81.7 IV Reported as 2207 local time 20 Jm by Caqkell (1943).

1900 Oct 10 30.3 81.7 EIght distinct shocks attributed to blasting.

1900 Oct 31 1615 30A 81.7 Iiot reported by Campbell (1943) or Hott .(1983).

1902 Nay 21 29.9 81.3 "noise like eamon fire" (Nott, 1983). Attributed to blasting.

29.9 81.3 1905 Sep 4 27.5 82.6 III "Richling noises (Not t, 1983).

1930 Jul 19 1853 25.8 81 A V Kuaerous, uidespread, evenly-spaced shocks. Attributed to blasting.

1935 Nov 14 0310 29.6 81.7 IV Tuo short tremors.

1935 Nov 14 0330 29.6 Sl.7 IV 1940 Dec 27 017') 28.0 82.5 f Not reported by Campbe(I (1943); attributed to blasting.

1942 JM 19 26.5 SI.O IV - Approximately 20 separate shocks reported in early afternoon throughout south florida.

Attributed to blasting or military activities.

t

14 Date ~tt Ut4 ~N ~cnII ~tt t CeINeents 1945 Dec 22 1525 25.8 $ 0.0 NeMspaper secants of citizens feeling tremor; event recorded at sae>> tls>> in Hobile, Alebmsa.

1948 Nov:8 1744 26.5 82.2 IV Accoapanled by sard of distant heavy explosion (Hott, 1983).

1952 Nov 18 2012 30.6 84.6 IV Felt ln Lake City and Oulncy, but not reported for tallahassee.

1953 Har 26 2$ .6 81 4 IV Slight tresor reported in Orlando.

1973 Oct 27 062I02.0 28.476 80.654 5 ka depth, 3.5 Hn aegnitude assigned.

1973 Dec 5 1130 30.5 86.5 Attributed to blasting.

.1975 Oec 4 1157 29.2 81.0 IV 2.9 Hn segnl tude assigned.

197$ Jan 12 2110 28.1 81.6 . IV Not recorded by local selsaograph.

197$ Nov 6 30.20 82.65 IV 1978 Nov 14 20I4 30.2 82.6 197$ Nov 16 82.6 N N N N

earthquake centered near Havana, Cuba (Campbell, 1943). Numerous reports of events in the weeks following the major 1886 earthquake in Charleston reflect the series of aftershocks as well as the general apprehension of a sensitized and fearful populace..

Campbell's compilation was included in an expanded report of Florida earthquakes presented by Mott (1983). Mott identified 33 events and attempted to estimate Modified Mercalli intensities, but admitted that "Many... seem to be related to seismic events elsewhere in North America." Using similar sources available to Mott, Reagor et al. (1987) prepared a seismicity map of Florida and compiled epicenter locations for Florida events. Table 1 represents a complete listing of those events presented as having been felt in Florida.

Modified Mercalli intensities are included, although most of the values were assigned on the basis of newspaper reports considerably after the earthquake reports. Most of the values are III or IV. Only six events exceed IV; two of those are attributed to blasting, and two others are from reports from more than a century ago.

Among those reported tremors compiled in Table 1, many listings are without convincing evidence, and others are more logically attributed to blasting activities. Campbell (1943) describes an event for 29 Oct 1727 which is based on secondary reports only and apparently coincided with reported disturbances in New England and the West Indies. Mott (1983) provides the same description, but, give the date as 12 Oct 1727. In addition, Mott lists a "mild" tremor with no damage at Pensacola for 6 Feb 1780 and a severe event affecting a military installation at Pensacola on 8 May 1781. Reagor et al. (1987) do not list the 1727 event, but use a description for the 6 Feb 1780 event that Mott used for the 8 May 1781 event. Reagor et al. describe the event as having occurred during a violent thunderstorm with "raging seas." The possibility of a hurricane or other meteorological phenomena being the source of a perceived

/

87o 0

/

85o 84o as' 82'1o Pensacola 0 slo Tallahassee 29 Jacksonvi le ainesville St. Augustine so'GAI) 28 1975 29 Orlando 197-270 ampa Q 28o 26 27 25o tii ami 26o 25 85o a4'SO 82o 8lo 80

/ / / / /

Figure 1. Oistribution of Epicenters for Florida Earthquakes as reported by Reagor et al. (1987)

(open circles). Closed circles depict cities .

The 1973 and 1975 events are labeled. Station GAI in Gainesville began operations in late 1977.

disturbance and subsequent damage for that report must be considered as credible.

Eight "shocks" reported for 10 Oct 1900, disturbances associated with "noise(s) like hearing cannon fire" on 20-21 May 1902, and 5-7 shocks spaced at 3 minute intervals in south Florida on 19 Jan 1942 are examples of events which are best interpreted as results of blasting or military activities. An earthquake on 12 Jan 1879 appears to have been felt throughout a wide area of north Florida and south Georgia (Campbell, 1943) and was subsequently assigned a north central Florida location for its epicenter (Mott, 1983). Although this event appears to have been a major earthquake, its location in Florida is based entirely on newspaper accounts and not scientific observations.

The territory of Florida had a population of less then 35,000 in 1830. At that time, St. Augustine was the only recognized city, and it had been the center of population since its settlement, in 1565. By 1860, the population was still only 140,000 and was concentrated in the St. Augustine and Appalachian River areas (Fernald, 1981). The population growth in south Florida did not occur until the last half century. Consequently, the geographic distribution of events reported as earthquakes was initially limited to the St. Augustine and other populated areas and gradually expanded to mimic the pattern of population growth.

The credibility of reports, however, has increased in recent decades. A small event occurred in 27 Oct 1973 and was felt throughout a large area centered around Seminole County (Fig. 1). Another event was felt around the Daytona area on 4 Dec 1975. Neither event was sufficiently severe to be recorded by seismograph stations near Mobile, Alabama, or Atlanta, Georgia, but estimated magnitudes (see Table 1) were 3.5 Mn or less. A single component, short-period seismograph station (GAI) was installed in Gainesville at the r

University of Florida in Autumn, 1977 (Smith, 1978). No reportable events in Florida have been recorded since that time.

Reports of "earthquakes" in Florida have occasionally appeared in the news media during the past ten years, but no substantiating evidence for these events has ever occurred in the seismographic records. The reports usually originate from credible lay observers who have actually sensed a disturbance. Reports of audible disturbances typically accompany the earthquake reports, and both sensations are commonly noticed over a broad time period (hours) and geographic area (e.g., Lake City to'Panama City). These events are attributed to atmospheric phenomena, and, in the cases carefully investigated by local civilian authorities, have been shown to be a result of military aircraft activity. In addition, there is a long history of unexplained "mystery booms" endemic to Florida's coastal areas. Atmospheric shock fronts are apparently perceived by individuals as disturbances emanating from the subsurface. But continuous seismographic observations, including intensive field testing with USGS portable seismographs in 1981, have failed to detect any associated ground motion.

All four of the 1978 events listed in Table 1 failed to be recognized at station GAI. A subsequent review of the seismograms for the time periods reported reveals no evidence of a local earthquake. Accordingly, those events are relegated to a status of "probable atmospheric origin." Similarly, the 18 Nov 1952 event (Table 1) reported as having been felt in Quincy and Lake City (Mott, 1983) (but not in the inter]acent Tallahassee), is not verified by seismographic records and can be attributed to atmospheric phenomena.

FLORIDA BASEMENT Shallow-focus seismic events are manifestations of stress accumulations and releases, and are exemplified by the presence of active tectonic features, existing faults capable of C

accommodating displacement, or isostatic imbalances requiring ad]ustment among basement complexes. Deep- or intermediate-focus earthquakes appear implausible for Florida because the configuration of

/ / /

85o 84o 83o 82o 81o 870

~ ~

31o Suwannee Basin of Tallahassee Paleozoic Sedim.

Graben Rocks 30o ~

Zone of Jay Faul~t Pan-African 29 Granites and Rhyolites 270 28o Mesozoic Volcanic 27o Rocks 25 26o 25 85o 84o 83'2o 81o 80 I / I I Figure 2. Simplified Hap of Florida Basement Features (after Barnett, 1975, and Smith, 1982).

lithospheric plate margins with which such events are associated excludes the Florida Plateau from currently-recognized zones of dynamic tectonic activity.

The geologic history of the Florida Plateau for the Cenozoic Era (Puri and Vernon, 1964) is one of the continual deposition of clastic and carbonate sedimentary rock layers of the Coastal Plain accompanied by, uniform regional uplift.

There is no evidence for active faulting on a large scale during the Holocene Epoch, and quite probably for most of the Neogene Period. Proposed deformational movements of local extent have been based on variations in the thicknesses of surficial and subsurface formations. Any deformation within the overlying Coastal Plain sedimentary blanket, if verified, would be interpreted as indicative of differential motion of structural units in the pre-Cretaceous basement underlying Florida. An absence of significant evidence of subsurface differential motion is suggestive, although not demonstrative, of a probable seismic quiescence for the Florida peninsula.

Applin's (1951) early description of the relatively flay-lying, undeformed, and unmetamorphosed lower Paleozoic subsurface sedimentary rocks of north Florida emphasized the unconformity below the basal Cretaceous rocks of the Coastal Plains sequence. Basically, Applin portrayed a basal Florida as consisting of a Suwannee Basin (Banks, 1978) of Ordovician and Silurian sandstones and".shales lapping onto a triangular-shaped granitoid batholith in central Florida. Subsequent descriptive and radiometric dating efforts by Bass (1969) and Milton and Grasty (1969) identified the granitic materials as having a Cambrian age similar to Pan African granites. Additional work by Barnett (1975) contributed to the realization that the south Florida basement consisted of,early Mesozoic basalts and rhyolites.

Barnett (1975) presented a detailed map of subsurface Flor'ida lithology and

. structure, but many proposed fault lines were imaginative and were based on

interpretations of gravity and magnetic anomaly patterns. His proposals included a northeast-trending Triassic graben underlying the Apalachicola Embayment. This feature was later described by Smith (1982) as the Tallahassee Graben (Figure 2) which was the site of abortive rifting in the Triassic Period.

It underlies a zone of downwarped sedimentary layers, known as the "Suwannee Straits" (Puri and Vernon, 1964), within the Coastal Plain sequence. Although the graben is flanked by normal faults (e.g., Smith, 1983), and subsurface structural features suggest significant vertical adJustments among distinct basal blocks during the Jurassic Period, there is no evidence in the Coastal Plains rocks of continued displacement during the Cenozoic Era.

Including the Ordovician and Silurian sedimentary rocks as part of the Florida basement, Wicker and Smith (1978) presented isometric views of the e peninsular basement. The depth of the basement varied from approximately 0.9 to the Paleozoic sedimentary rocks in northern peninsular Florida to over 4.5 km km to the Mesozoic volcanic rocks in southern Florida. Although no drill holes have completely penetrated the Paleozoic sediments, they are presumed to be underlain by the Pan African granitic rocks, Using gravity anomaly magnitudes, Wicker and Smith (1978) estimated their maximum thickness to be approximately 2.5 km. Nelson et al. (1985a,b) interpreted COCORP results in north Florida to indicate approximately 6 km of Paleozoic material over the granitic rocks, but they indicated that the bottom 3 km may be an extension of the volcanic material associated with the granitic batholith in the north Florida basement and dated as Ordovician (Mueller and Porch, 1983).

The isometric views presented by Wicker and Smith (1978) also emphasized the apparent abrupt truncation of the granitic batholith on its southern end.

Puri and Vernon (1964) termed this feature the "Kissimmee Faulted Flexure" and the basal area to the south the "Osceola Low." This line of truncation was represented by a right-la't'eral fault by Barnett (1975). Smith (1983) named the

feature the "Jay Fault" and presented evidence for left lateral motion during the Jurassic Period. Klitgord et al. (1984) described the same feature as a Jurassic transform fault which aligned southern peninsular Florida with northern Florida. Recent articles by Dallmeyer (e.g., Dallmeyer et al., 1987) suggest extreme Triassic and Jurassic displacement to move the southern half of the Florida peninsula from a position in what is now the Gulf of Mexico into Juxtaposition with northern peninsular Florida. There is no evidence from the overlying Cenozoic sedimentary strata to suggest any activity along this fault in the last 60 my.

The shallowest depth to the basement, approximately 0.9 km, is in north central Florida. Based on borehole samples and depths, this area of'he basement became known as the "peninsular arch" (Puri and" Vernon, 1964) . This description inferred an anticlinal posture of the basement rocks with a north-south trending axis. Furthermore, an exposure of the Eocene Ocala Limestone in north central Florida led to the term "Ocala Uplift" (Vernon, 1951). Winston (1976) correctly pointed out that the feature is a result of anomalous thickening and not of Neogene tectonic activity. The peninsular arch has been redefined (Smith, 1982) as an erosional remnant of Paleozoic sedimentary rocks over which the Coastal Plain sedimentary rocks are draped.

Neither the peninsular arch nor the Ocala Uplift, dhspite their misleading names, is a source of any faulting or other tectonic activity.

Citing previously published evidence for Gondwanan paleontological -and geological affinities within the Paleozoic sedimentary rocks of north Florida, Smith (1982) proposed a tectonic history in which the Florida basement was an original component of an Afro-South American landmass during early Paleozoic time (Figure 3). Paleomagnetic evidence substantiates a southern hemisphere site for Florida during the Ordovician Period (Opdyke et al., 1987), and radiometric age correlat5ons of Suwannee Basin detrital muscovite with west

~

Africa Bove Basin sedimentary rocks suggest a West African terrane linkage

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tW Figure 3. Middle Silurian paleogeographic reconstruction showing Florida Basement as part of an Afro-South American Landmass (from Opdyke et al., 1987).

(Dallmeyer, 1987). The proposed history involved subductive closure of an intervening ocean and a suture with the southern margin of the North American landmass. Nelson et al. (1985a,b) and Tauvers and Muehlberger (1987) have discussed the proximity of the suture zone with the well-known. Brunswick Magnetic Anomaly.

Seismic activity during the late Paleozoic continental convergence would, of course, have been significant, perhaps similar to the present day situation in India. Furthermore, the subsequent rupturing of the continuous Pangaea landmass during the Triassic period and the divergent migration of the African and South American land masses from a new boundary line in the late Triassic-early Jurassic time are envisioned as very dynamic events associated with intense seismicity. The exact mechanism of the original interactions of rifting continental blocks remains unresolved (Smith, 1983; Klitgord et al.,

1984; Dallmeyer, 1987), but an initially chaotic fragmentation of blocks occupying the present northern Gulf of Mexico appears probable (Figure 4). The Jay Fault also appears to have played a significant role in the early Mesozoic plate interactions.

BASEMENT RELATIONSHIP TO FLORIDA SEISMICITY The reconstructions of the tectonic history of the Florida basement, which tg are based on very limited borehole samples and interpretations of geophysical field anomalies,~suggest that the entire Florida peninsula and, indeed, much of south Georgia outboard of an inferred paleosuture zone is a displaced terrene of west African origin. Although the seismicity of the area was presumably much greater in the past, it is, consistent with expectations, virtually nil at present. The current tectonic nature of the Florida basement is not only distinct from the typical southeastern United States basement with continued Appalachian orogenic ad]ustments, but, by virtue of its distance from

'tectonically active lithospheric margins and its lithospheric stability, it is

NORTH AMERICA

~ Tallahassee.

~~ Graben Suture ~~!.

Line ~

Jay ~ 'aul '~ AFRICA Initiating Point Rift of Rifting Segments SOUTH AMER ICA

~

Transform Faults Figure 4. Theoretical Oepiction of the Configuration of Landmasses and Tectonic Features at the Start of Triassic Rifting.

apparently free of potentially disruptive stresses or continuing fault displacement. Hoyt (1969) and Winker and Howard (1977) described an apparent irregularity among ancient Florida shorelines as evidence of tectonic motion of the Florida peninsula during the late Cenozoic. Opdyke et al. (1984), citing density changes from karstification of limestone formations as a cause of isostatic adjustments, attributed the elevation differences of ancient shorelines to epeirogenic uplift during the Pleistocene Epoch.

Although a fault mechanism to accommodate epeirogenic uplift has not been identified, nor have strain rates been computed'or an uncompensated unloading of the peninsular crust, there remains no evidence of current conditions or features conducive to the stress accumulation characteristic of a shallow focus earthquake. Bollinger (1973), reporting on:the seismicity of the southeastern United States, presented no listing of events in Florida, but attributed recent seismicity to strain development induced by crustal uplifting I and concentrated by old Appalachian structures. A seismicity map of the United States includes for Florida only the 4 Dec 1975 event at Daytona for the period 1975 to 1984 (Stover, 1986). A compilation of earthquakes for the southeastern United States for the 1977-1983 period (SEUSSN contributors, 1985) listed no events in Florida. In fact, an abrupt decrease in seismicity appears to exist south (outboard) of the proposed suture zone separating Appalachian structures from the more stablefGondwanan basements.

According to available records, only one (the 22 Dec 1945 event) of the reported Florida earthquakes in Table 1 was recorded by a seismograph. Many recent (1978 to present) reports of tremors in Florida have been dismissed as non-tectonic because the existing seismograph station has recorded no ground motion. Accordingly, the tectonic origin of many of the events listed in Table 1 is not only subject to review, but probably doubtful.

Table 2. Seismic Events in Florida Attributed to Tectonic Origin.

Exact locations given in Table l.

Date Location 13 Jan 1879 Uncertain; felt throughout north Florida and South Georgia 21 Jun 1893 Jacksonville 14 Nov 1935 ,

Palatka 22 Dec 1945 offshore Miami 27 Oct 1973 Merritt Island 4 Dec 1975 Daytona

A revised list of known earthquakes from the Florida basement (Table 2, Figure 5) is based on a critical analysis of those events listed in Table l. Of the six events listed, only three (1935, 1973, 1975) appear to be well-located.

The 1893 and 1945 events are listed with the least confidence. Although the 1879 event is well-described in early newspaper accounts, an exact epicenter is difficult to identify, and the event could have originated throughout a wide spatial range of north Florida or south Georgia, Figure 5 delineates those basement boundaries separating contrasting lithologies and the probable areas of old faults which conceivably could experience continued displacement. The events listed in Table 2 are positioned, and five of the six, given the uncertainties surrounding their epicentral determinations and speculation associated with fault placements, can be regarded as closely associated with supposed subsurface faults in the Florida basement.

Given the absence of confirmed events associated with the Jay Fault and the Traissic graben faults, the stability of post-Paleozoic faults can be described as relatively substantial.

The five epicenters coinciding with proposed basement faults lie above either pre-Mesozoic or continental-oceanic boundaries. Continued ad]ustments on these features, even as infrequently and mildly as is shown herein, is plausible.

Y Conclusions The ma)or conclusions of this essay can be summarized as follows:

1. The number and magnitude of reported seismic events in Florida is very limited. This may be attributed in part to the sparse population of Florida prior to this century. Upon critical review, however, only six events (since 1879) emerge as having a probable tectonic origin.
2. Geological and geophysical evidence cdnvincingly demonstrates the original Florida basement to have been a part of an early Paleozoic Afro-South American

/ / /

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.i l 975

~ ~ ~

29 1973 270 Osceola Complex 28o~

of Granite and Rhyolite l l

Mesozoic.

Volcanic 27'945 250 Rocks 25o 25 85o

/i 84o 83 '2 81o 80

/ I I / I Figure 5. Revised version of Florida Basement Features with Epicenters and Dates of Florida Earthquakes Attri-buted to Tectonic Origin. Solid Lines are Faults of Mesozoic Age; Broken' Lines Delineate Faults of Early Paleozoic Age.

landmass which converged with North America during the late Paleozoic.

3. Continental rifting of the Pangaea supercontinent during the Triassic period and subsequent divergence of landmasses left Florida, with south Georgia and Alabama, as an exotic or displaced terrane attached to North America along the original convergence suture line. Accordingly, the Florida basement is lithologically and tectonically distinct and more stable than the seismically active Appalachian area which was the original margin of North America.
4. The intensity of seismicity apparently is abruptly diminished south of the original Paleozoic suture line which crosses south-central Georgia on an approximate east-west trend.
5. The seismic nature of Florida cannot be compared with and is not related to that of the remainder of the eastern United States.

REFERENCES

1. P.L. Applin. ".Preliminary report on buried Pre-Mesozoic rocks in Florida and ad]acent States." U.S. Geol. Surv., Circ. 91, 1951, 28 pp.
2. J.E ~ Banks. "Southern Florida subsurface features related to oil

. exploration." Trans. Gulf Coast Assoc. Geol. Soc., v. 28, 1978, pp.

25-30.

R.S. Barnett. "Basement Structure of Florida and its tectonic implications." Trans. Gulf Coast Assoc. Geol. Soc., v. 25, 1975, pp.

122-142.

4. M.N. Bass. "Petrography and ages of crystalline basement rocks of Florida

- some extrapolations." An. Assoc. Pet. Geol., Mem. 11, 1969, pp. 283-310.

5. G.A. Bollinger, "Seismicity and crustal uplift in the southeastern United States." Am. Jour. Sci., v. 273-A, 1973, pp. 396-408.
6. R.B. Campbell. "Earthquakes in Florida." Proc. Fla. Acad. Sci., v. 6, 1943, pp. 1-4.
7. R.D. Dallmeyer. "40Ar/39Ar age of detrital muscovite within Lower Ordovician sandstone in the coastal plain basement of Florida:

isplications for west African eerrana linkages." ~Geola, v. 15, 1987, pp.

998-1001.

8. R.D. Dallmeyer, et al. "Emplacement age of post-tectonic granites in southern Guinea (West Africa) and the peninsular Florida subsurface:,

implications for origins of southern Appalachian exotic terranes." Geol.

Soc. Amer. Bull., v. 99, 1987, pp. 87-93.

9 ~ E.A. Fernald, edit. Atlas of Florida. Tallahassee: Florida State Univ.

Fndn., Inc., 1981, 276 pp.

10. J.H. Hoyt. "Late Cenozoic strucutral movements, northern Florida."

Trans. Gulf Coast Assoc. Geol. Soc., v. 19, 1969, pp. 1-9.

11. K.D. Klitgord, et al. "Florida: a Jurassic transform plate boundary."

Jour. Geo h s. Resep v. 89, 1984, pp. 7753-7772.

12. C. Milton and R. Grasty. "'Basement'ocks of Florida and Georgia." Am.

Assoc. Pet. Geol. Bull., v. 53, 1969, pp. 2483-2493.

13. G.J. Mott. 8 r bcatk ubaisacery of Florida: 1727 co 1981." Florida Scientist, v. 46, 1983, pp. 116-120.
14. P.A. Mueller and J.W. Porch. '"Tectonic implications of Paleozoic and Mesozoic igneous rocks in the subsurface of peninsular Florida." Trans.

Gulf Coast Assoc. Geol. Soc., v. 33, 1983, pp. 169-174.

15.. K.D. Nelson, et al. "New COCORP profiling in the southeastern United grates. 1: late Paleozoic suture and,Mesosoic 13; 1985a, pp. 714-718.

rifr basin.'Geolo ., v.

16. K.D. Nelson, et al. "New COCORP profiling in the southeastern United States. II: Brunswick and east coast magnetic anomalies, opening of the north-central Atlantic Ocean." 8~solo, v. 13, 1985k, pp. 718-721.
17. N.D. Opdyke, et al. "Origin of the epeirogenic uplift of Pliocene-Pleistocene beach ridges in Florida and development of the Florida karst ".~Gaolo, v. 12, 1984, pp. 226-228.
18. N.D. Opdyke, et al. "Florida as an exotic terrene: paleomagnetic and geochronologic investigation of lower Paleozoic rocks from the subsurface of Florida." ~Geolo, v. 15, 1987, pp. 988-983.
19. H.S. Puri and R.O. Vernon. "Summary of the geology of Florida and a guide book, to the classic exposures." Fl. Geol. Survee Spec. Publ. No. 5, 1964, 312 pp.
20. B.G. Reagor, et al. "Seismicity map of the state of Florida." U.S. Geol.

Surv., Map MF-1056, 1987, 1 sheet.

21. C.F. Richter. Elementa Seismolo . San Francisco: W.H. Freeman, 1958,
p. 5.
22. SEUSSN Contributors. "Availability of a six-year (1977-1983) earthquake catalog for the southeastern United States derived from network monitoring.

Bull. Seis. Soc. Amer., v. 75, 1985, pp. 629-633.

23. D.L. Smith. "Earthquake seismograph station at the University of Florida."

Florida Scientist, v. 41, Sup. 1, 1978, p. 35.

24. D.L. Smith. "Review of 'the tectonic history of the Florida basement."

Tectono h sics, v, 88, 1982, pp. 1-22.

25. D.L. Smith. "Basement model for the panhandle of Florida." Trans. Gulf Coast Assoc. Geol. Soc., v. 33, 1983, pp. 203-208.
26. C.W. Stover. "Seismicity map of the conterminous United States and ad]acent areas, 1975-1984." U.S. Geol. Surv., Map GP-984, 1986, 1 sheet.
27. P.R. Tauvers and W.R. Muehlberger. "Is the Brunswick Magnetic Anomaly really the."Alleghanian suture2" Tectonics, v. 6, 1987, pp. 331-342.
28. R.O. Vernon. "Geology of Citrus and Levy counties, Florida." Fla. Geol.

Surv., Bull. 33, 256 pp.

29. R.A. Wicker end D.L. Smith "Re-e.valuatind the Florida hesement." Trans.

Gulf Coast Assoc. Geol. Soc., v. 28, 1978, pp. 681-687.

30. C.C. Winker and J.D. Howard. "Correlation of tectonically deformed shorelines on tha southern Atlantic coastal plein 'Genie, v. 5, 1977,

, pp. 124-127.

31. G.O. Winston. "Florida's Ocala Uplift is not an uplift." Bull. Am. Assoc.

Pet. Geol., v. 60, 1976, pp. 992-994.

DURATION OF STRONG GROUND MOTION by Bruce A. Bolt I r

SYNOPSIS Duration of strong seismic shaking is a sensitive function of wave Ireceuenc r, am l.itude threshold, and Richter ma nitude. The magqitude dependence arises from the finite geometry of fault rupture. Frequency dependence enters through the exponential attenuation law for rock; for larger earthquakes (greater fault breakage), duration I of'igher frequency

() 1 Hz) horizontal waves with amplitudes above 0.05g ground acceleration is unlikely to exceed 35 to 40 sec. Lack of precise definition has led to exaggerated estimates of duration for some design ourposes. Filtered records of ground acceleration yield a table for "bracketed duration" as a function of magnitude and source-to-site distance.

INTRODUCTION The ing is prediction of the duration still rather D (in seconds) rudimentary even though "d a~in le most imnortant factor in oroducin

's of strong seismic shak-ossibl the-excessive dame e" (H.H. Engle, in Richter, 1958). In two recent textbooks on earthquake engineering (Wiegel, 1970; Newmark and Rosenblueth, 1971) no explicit treatment of duration as a function of many variables is attempted. Housner's (1965) tially a linear law against magnitude M:

D= llM-53.

Esteva and Rosenblueth (1964) define the duration s of an "equivalent" ground motion with uniform intensity per unit time (about half D for large M) as s = 0.02 exp'(0.74 M) + 0.3r (2) where r km is the source distance (FS in Figure 5). ~

These formulae do express the key dependence of D on M which can 'be inferred at once from the rupture model of earthquakes (e.g. Bolt, 1970) illustrated by the diagram in Figure 5, i.e. M increases with AB. What the formulae lack .is a stated threshold of ground acceleration A to define'"strong" and a treatment of frequency. Seismic surface waves (Love and Rayleigh type) attenuate (assuming no dispersion) like A A Ei'g (3) where E gg exp (-1T f r/cg). (4)

IProfessor of SeismCilogy, University of California, Berkeley.

1304

f is frequency (in Hz), c is wave velocity and Q is the mean specific dampi'ng constant for the appropriate rocks and soils.

As (4) shows, because high frequency waves attenuate more strongly than low frequency ones, their duration is severely distance limited.

Any linear law, such as (1), overassesses duration for large earthquakes, at least for 1 Hz and higher frequency waves (e.g. the frequency invariant estimates of Page et al.t ~ 1972). The last term of (2) is pnysically inad-missable for the same reason: as r increases, the amplitudes (and hence, in general the mean durations above given thresholds of shaking) decrease like (3).

DEFINITION OF DURATION Two definitions appear useful.

(a) "Duration at a particular frequency is the elapsed time between the first and last acceleration excursions greater than a given level say)." I propose to call this interyal the "bracketed duration". '0.05g, It is sometimes measured by cumulatively adding the squared accelerations and adopting the 95 percentile time interval (Husid et al.t,t 1969). Par-ticularly for earthquakes with specially complex multiple sources (e.g.

Wyss and Brune, 1967), this definition often leads to a non-physical uoper

. estimate. Spectrograms like Figure 1 (Pacoima, 1971; R. Arms, personal com-munication) show well the complex amplitude spectrum as a function of time (e.g. Perez, 1973); peak accelerations of 2-3 Hz waves occur at 4 and 8 secs with reduced motion between (see also the quiet interval on the 2 Hz

. trace of the Olympia record'Figure 2) with unfiltered peak A equal to 0.31g.) For some design and liquefaction analyses the episodes of relative-ly weak motion may allow some structural recovery and snould be excluded.

(

(b) "Duration at a particular frequency is the total time for which acceleration at that f exceeds a given value." This interval, called "uni-form duration" here, may equal the corresponding "bracketed duration" (as on the 2 Hz trace (Figure 3) of the Castaic record (A)0.05g), with an un-filtered peak A of 0.39g) or be much less (as, on the 1.0 Hz trace). Uni-form duration appears to have a'greater mechanical signif'cance in some design tests. Circles and t:riangles plotted in Figure 5 are measured uniform durations from accelerograms.

DURATION AS A FUNCTION OF FREQUENCY Nine strong motion records from the U.S. with large recorded horizon-tal accelerations were passed through a narrow-band Krohn-Hite filter at representative central frequencies (see Figures 2 and 3). For each record the attenuator setting was fixed for all frequencies. The measured dura-tions are shown as dots in Figure 4. The great variability in shaking patterns is exemplified by the San Fernando earthquake which gave at Castaic (Figure 3) the largest motions at 4 Hz early in the shaking while at Pacoima high frequency bursts came towards the end (Bolt, 1972 and Figure 1). This real-time variability is, of course, lost spectra only are used in analysis.

if frequency The values in Figure 4 confirm that, generally, the greatest D (above

~ ~

1305

the modest level' 0.05g} occurs in the frequency band 1 < f < 5 Hz. On the low-frequency side~seismological research, indicates that earthquake source mechanisms dec'rease amplitudes roughly like f. For high fre-quencies, D is limited by attenuation along the propagation path.

Table 1 gives values of shear (or Love) 'wave'ttenuation calculated from (3) taking Q . 150, c ~ 3 lan/sec. CThe amplitude is set, at 5'km from the source, equal to A, ~' E /, r, for large Q.) Suppose the site S (Figure 5) is near the'nd of a fault length AB. The empirical correla-tion between M and fault rupture length is listed in the first two columns of Table 1. Suppose, to obtain an upper bound, waves of all frequencies are generated at the moving rupture with an amplitude of 1.0g. Then, zig-zag line indicates, at each frequency, beyond a certain distance as'he on the slipping fault, SA (=r) is too great for the site S to continue to receive waves with A > 0.05g. For example, after the rupture has propa-gated to 150 km (corresponding to M ~ 7.5) little 1 Hz (or greater) energy above 0.05g will ultimately arrive back at S. In other words, even for the greatest magnitude shocks (M > 8.0) the duration (A > 0.05g) at S (f > 1 Hz) would be no longer. The slope of this geometrical maximum is shown as a broken line in Figure 4.

CALIBRATION OF TABLES Measurements of world-wide strong-motion records were used to fix the curves for D versus M in Figure 5. The curves represent nearly the upper bound so as to include 90 per cent of available data. Many published val-ues (e.g. Donovan, 1972) fix the low magnitude end. Because no similar population is available for large magnitudes, the attenuation values of Table 1 Provide the sloPe for M > 7 ' as exp]ained above Four points above the curves in Figure 5 need discussion. The Hiroo record (from the 1970 Hidaka Sankei earthquake (M = 6.8)) shows an un-usually long D of almost monochromatic shaking (f =5 Hz) above 0.05g (Omote et al., 1970). In this case, the uniform duration almost equals

" the b'ra0keted"'durati'on'nd"a'"'se0o'nd 'ene'rgy"bus'st"ar'&i've's 'l4'"dec "from"the "'"'

onset suggesting a significant multiple dislocation.

~ f The 1906 earthquake value (Lawson, 1908) comes from timed e'stimates o' 40 sec of ."severe shaking" .felt by, the scientists A. McAdie, (San Francisco) and A.O. Leuschner (Berkeley). The E-W component of the Ewing seismograph at Lick wrote an almost continuous record. It suggests that motions with periods less than 2 sec had fallen below A=O.Olg after 40 sec; smaller fluctuating. waves (periods > 3 sec) were recorded for 150 sec or so.

Imamura (1925) reproduced the only other record available from the center of a major earthquake. In the 1923 Kwanto shook an E-W seismograph oper-ated at Hongo almost uninterrupted (pendulum period 10 sec, magnification 2). Extreme (discontinuous) oscillations of high frequency ended about 30 sec after the onset of the S waves. Then, for over 2 minutes, the pendu-lum recorded longer period ~aves (=5 sec) of smaller A (<< 0.05g), fol-lowed by aftershocks.

There is, of course, much evidence that longer period waves than

considered in Table 2 and Figure 5 persist for a minute or more at accel-erations A ( 0.05g, 'because of sharply lower attenuation and surface wave dispersion (e.g. '.fooney and Bolt, 1966). Figure 6 demonstrates this prop-75 km from the 1969 Santa Rosa shock (M 5.7). The unfiltered top 'rty trace clipped in the recorders; vertical lines mark 10 sec). At 5 Hz, D 10 sec while at 2 sec, D 70 sec; however, the ground acceleration is less than 0.01g at all frequencies.

The long period .vibrations, taken with the aftershocks, add to the human propensity to exaggerate the duration of shaking. (Humans can feel A> 0.001g). Some people in the 1964 Alaska earthquake reported feeling motions for 150 sec (Kachadoorian and Plafker, 1967). The only close "instrumental" record in 1964 is the tape recording of a radio announcer's reaction near Anchorage (Pate, 1965). Many replayings of this remarkable felt record convince me that the audible background noise and voice re-sponse ("...has not stopped shaking yet") are consi'stent with cessation (A> 0.0lg) of high frequency shaking after 45 sec.

CONCLUSIONS Durations of higher frequency shaking do not significantly increase above magnitude 7.5 for A> 0 '5g and above magnitude 7 for A> 0.10g.

Bracketed durations (f> 1 Hz) within 25 km of the fault rupture are n'ot 1'ikely to exceed the following values (see Figure 5) for A> 0.05g and A> 0.10g, respectively:

D = 17.5 tanh (M-6.5) + 19.0, (5) and D 7.5 tanh (M-6.0) + 7.5. . (6)

Table 2 gives D as a function of magnitude and distance from the source (A km); It was constructed using (5), Table 1 applied to the fault rupture model of earthquake genesis, and spectrally filtered records sucn as

. Figures 2 and 3. The observational scatter indicates that the chance of

.exceeding..the tabulated values..by 20 per cent, or more is. about..l in 10.

,- --=...,',=...-Ify,.thanks....for;;.assistance".to...R.P,,;.Arms, W,.K ...Cloud. S.,
,Dickman,.,N,.

Donovan and R. Sell. This research was supported by NSF Grant GI-34507,.

' BIBIiIOGRAPHY p ~ '*

Bolt, B."A. '(1972) "San Fernando Ruptu'r'e Meehan'i'sm and the Pacoima Strong-Motion Record", Bull.'eidm"." Soc. A'm.', '62,"1'039-1'04'5.

Edited by R.L. Wiegel,'rentice-Hall, New Jersey.

Donovan, N.C. (1972) "Earthquake Hazards for Buildings", National Workshop on Building Practices for Disaster Mitigation Nationa'ureau of Standards, Boulder.

Housner, G.W. (1965) "Intensity of Ground Shaking Near the Causative Fault",

Proceedings of the Third World Conference on Earthouake Engineering, Vol. 1, New Zealand.

1307

zsid, R., H. Medina, J. Rios (1969) "Analisis de Terremotos Norteamei Ricanos y Japoneses", Revista del IDIEA, 8, Chile.

r mamura, A. (1925) "The'reat Kwanto, (S.E: Japan) Earthquake on September 1, 1923", in ~Re orts of the Imperial Earthquake Investiga-tion Committee, No. 100A, Tokyo.

wchadoorian, R. and G. Plafker {1967) "Effects of the Earthquake of urch 27, 1964 on the Communities of Kodiak and Nearby Islands",

U.S. Geol. Surve Paper 542-F.

tionn, IamsonA,.C. (1908) "The California Earthquake of April 18; 1906", ~Re ort of the State Earthquake Investigation Commission, Carnegie Institu-Washington, t

D.C.

Mooney, H.M. and B.A. Bolt {1966) "Dispersive Characteristics of the First Three Rayleigh Modes for a Single Surface Layer", Bull. Seism.

Soc. Am., 56, 43-67.

Newmark, N.M. and E. Rosenblueth (1971) "Fundamentals of Earthquake Engineering", Prentice-Hall, New Jersey.

S., Y. Sakai, Y. Ohsa~i, t4. Watabe, Y. Matsushima, Y. Yamazaki, and

'mote, H. 'furata (1970) "Investigations and Analyses on Some Very Strong-Mo tion Ear thquakes Hidaka Sankei Earthquake"; International Institute of Seismology and Ear thquake Engineering, Tokyo.

Pa'ge; R.A;;"D':M.'Boore, 0 Bq'o'yner',"and'.Q. 'Coult'er'197'2) "Gjo'u'riG Mo'tion Values for Use in the Seismic Design of the Trans-Alaska Pioeline System", "'solo ical Survey Circular 672, U.S.G.S., Washington, D.C.

Pate, R.A. (1965) "The Prince William Sound, Alaska, Earthquake of 1964

~ ~ - and Aftershocks", Phono raph "Record, reproduced by U.S. Department of Commerce, Washington, D.C.

Perez, .V. (1973)."Velocity. Response Envelope Spect'rum as a. Function of Time, Facoima Bam, San Fernando Earthquake, February 9, 1971", Bull.

Seism. Soc. Amtt 63, (in the press).

s Richter, C.F. (1958) "Elementary Seismology", W'.H.'Freeman, ~

San Fr'ancisco.

~ I s r Wiegel, R. L. (1970) (Ed. ), "Ear thquake Engineering", Prentice-Hall, N. J.

Wyss, M. and J.N. Brune (1967) "The Alaska Earthquake of 28 March 1964:

A Complex Multiple Rupture", Bull. Seism. S'oc. Am., 57, 1017<<1023.

1308

e e,

TABLE l Ground Acceleration Attenuacion Table-Function of Frequency H ".r 1/v r 8 Hz 5 Hz 2 Hz 1 Hz 0.5 Hz (km) E A/A E A/A E A/A E A/A E A/Ao 5 0.447: .756 .756 .840 .840 .933 .933 .966 ~ 966 .983 .983 5.5 10 0.316 .572 .405 .705 .499 .870 .615 .933 .660 .966 .682 6.0 20 0.224 .327 .163 .498..251 .756 .378 .870 .436 .933 .468 6.5 30 0,183 .187 .076 .351 .143 .658 .268 .811:331 .900 .3o9 6-3/4 50 0.141 .061 .019 .175 .056 .498 .157 .705 :221 .840 .264 7.0 70 0.120 .086 .022 .376 .101 .613 e166 .783 .210 7-1/4 100 0.100 .248 .056 .498 .1'2 .705 .159 7.5 150 0.081 .123 .022 '.351 .065 .592 .107 aa

8. 0 250 0. 063 . 175 ~ 025 . 418 . 058

.,, ... TABLE 2.." Bracketed.Duration",.(sec),,(Acc. > 0,.05g; f eql >;,2. Hz)

'1 Hag 5.5 6.0 6.5 7.0 7.5 8.0 8.5 10 8 12 19

" 26 34 "'5

",9

a

'5.

25,...; 24 .

'9 4 . 28 30 . 32 50 2

"" "" 3 ""'10 . 22 :26. '* 28

"" " '75 ',',., . ec

'1" ';" .: ~,5, I

" '10." - 14;, ~
16n. ". "17 C

= ~ 100,,-.'>>0 a

~;.,'...:.'..",1, ~,4...,'" ', '5.;. . ',."'; 6, '," .7,",, ,

125- 0 0 2 . 2 3 3

'150 0 0 .2 175 0 0 '0 0 200 0 0 0 0 0' 1309

~OltH Sl6E IO Hz P '

~ ~

~ ~

\

P ~

\ i q ~ ~et

~

I ~ ~

~

\> I P ~ ~

~ ~

~ ~

h g A I'P 03

~~ hhI h,,h, i) "hQt

!rich/

5 Sec FIG ilfi ii);

jlhlrhmrh

~

~ ~ ~

~ Ih h. ~

~

hh ~

~

..5 Hz h

~ r ~ h ~ h /

I Hz r fl I I'II 'If I I I INlrhhI'I6

6. BERKELEY 1310

~ ~ ~

~ "0 ~

2 " 4 6 8 lO "IR l4 l6 18 20 IO Hz, i II ]jl

)I'l, ll,l, II I I I'I

. II. i ill id~

II I il II II igiw fe I lf 4Hz 4~

I ~

IP 'P II f

~ . C I

2Hz n n V

v J

I.5 Hz t

f~

I 1.0 Hz

~ ~

~ I 0.75 Hz 0.5 Hz

- FIG 2 1311

I I .'p I )k.jii~+g1~PPQ~'

0 2 . 4 ~ 6 8 IO I2 '4 I6 IB 20 I0Hz l,,!ill I <.l I I, I I

'Vyp"~"~]:i> if'~"Pv~-"~~g'P'eQ>g'4.g

~ ~

n!i::.Il'q 'i/i;!:i'l!Pg-,lj'J~':jest J~ll@~tl,;

>Vv i /

~ ~ I 1.0 Hz ~

  • I

\

I 0.75 Hz"..

0.5 Hz FIG 3 1312

o

- Ceeeetrical Me cialaaI e

30 (teak acc i ear~tea It O.e CI Eave ley ~

~ 25 NISCI (I C ~ ~ lt ~ ~ OI

~o cts 20 15 ISCI IllI I

~1555 eer Ci ~ C~

~ lell tlc ~ I ~ C till rlC ~I~

~er 10

~ ~

~ o 5

~s 0 1 2 3 l 5 5 7 1 9 10 flG e freqaeac 1 INC>

FAULT RUPTURE LfNGTII

~ c~ ~

~ 5 ~ -. IO'0, d~ 30 -. 70.~ o l40, 260 ., 500 ot ~ ~ I ~

Ouro'etn > 0.05 O Isee u r c r 5 Q ourotton ) 0. I cl

+ Housnor l>970) 5oo risc1906 Ico 40 X Folr Estttttot ~

8toctteted 0 )005@ +

Koeoto tst) 8toclt ~ led 0 )O,l Cl I 4 h II ~ coin ~ o ~ ts i 49 30 I

D C Cirro o, ~

I 0 20 ~

~ OI7Alote ISO9 I

~ Ckecoentto ~,'.. e ~ ~ ..

0 hcocto~

I' TO ttogok tltee ~

r CS IO t em oIO taco ~ cortto rr

<rot.

pp Q II~ c ~ to ~ 1 ~

Q Q

+ Son tttoocteco I9$ 7 0

5 5.5 6 6.5 7 7.5 8 85 MAGNITUOE flG 5 1313

DURATION OF STRONG GROUND MOTION Discussion by Yoshimasa Kobayashi .II The duration given by Bolt is likely that measured from filtered records and in such a case the resu1t is necessarily strongly influenced by a bandpass filter employed. In measuring "filtered duration", therefore, the frequency characteristics of the filter shou1d be clearly defined, since otherwise some arbitrariness would be'introduced.

If an accelerogram with uniformly distributed frequency cpppnents is passed from 0.25 to 7 Hz(approximate frequency range for SMAC record) through an Octave- or I/2-Octave-band-pass filter, the output levels will be lower than the over-all level by the amount given in Table A.

The writer has studied some twenty SMAC records y)tained in Japan and derived an empirical formula for duration "exceeding" an arbitrary threshold acceleration d gals as log, t<- -0.00884 + 0.50M I.82 (sec) for'o) x 4 '0.5'IM - I.57 (lan) """" -" ."- ~

~

'-- ">- . "... ~: ....*

where M and r are the earthquake magnitude and hypocentral distance in km, respectively.(Fig.A)~

~

~.'..--According..;to.the..relation,,We..dmatioys,.gqr.. threshold,4, valise@ 0,05g .....

and 0.10g are respectively given by logt>~=0.50M 2.26 (sec) and logt =0.50M 2.70 (sec)

Thus the durations at Hachinone in the I968 Tokachioki earthquake of M 7.8

.,would be t~o=43.65 (sec) and',~ = I5;81 (sec) of unfiltered horizontal 'accelerations the other hand the, fluctuation

'n

...-..at Hachinohe,.in, the.esrthquakq an4 the durations-exceeding as shown in Fig.B and C, From. the figures

'tq<ws tgpg~

63 '(s~c) 37, (sec )" ED' t ~vs '227 (sec') "

(gee )

'"- ',, thresholds were The values determined'b'ove for Hachinohe except t~s~ are appreciably.

"'high'er'han those plotted by "Bolt(D+~~-"33. sec and.,Dye 5. sec'in, Fig..5)

~

~

The differences<are too great as to be attributable to the difference

~

between "uniform".,and "bracketed"durations and seem to be due to the effect of band-pass filtering as described above. In earthquake engineering the over-all acceleration(unfiltered acceleration) may be as well important as the filtered one according as each case involved and longer estimates referred to by the author (<) wnuld not always be "over-assessing".

Kobayashi,Y.,Effects of Earthquakes on Ground(II),Journal of Physics of the Earth Vol.I9 No.3, pp 23I/24I,I97I I Paper No.292 by B.A.Bolt II Assistant Professor, Disaster Prevention Research Institute, Kyo o University.

III Strong Motion Accelerograph'V "bracketed duration" of unfiltered acceleration

Table A Difference in Levels(dB) Betveen Filtered and Com Filter Octave nents(0.25 I/2-Octave Fre

..I Unfiltered Noise of Uniformly Distributed Frequency 9.8 7 Hz)

-I2.9(0.23)

Hz, 0.33) 2 Hz 6.7(0.47)

.8(0.33) 4 Hz

-3.6(0.66)

-6.7(0-47)

( denote amplitude ratios

~>¹ e ~

~2 u 10 5 ~1 O

o 5 /y ie 5

C+ Fig.CI

~ amtraseys and Svma

~ EW eKobayashi 0.N 5, a5eed 05 10 100 200 Threshold Acceleration Ct f gal) a~

~ i ~ .ai diii n i...

a 5 6 7 Magnilude M C Duration of ground motion exceeding arbitrary threshold values of acceleration; Fig. A Duration of strong shaking and the earth. Tokachioki earthquake, May 16, 1968, %=7.9,

,:.quake magnitude. 1. Gutenberg. and Richter;...

recorded at Hachinohe harbor, 8=180 km.

~

logtefe=.. 0.25%-,.0.7,..i2;.Housner: .feM1M-.52;

3. Ambraseys and Sarma. fe-,11.5 M-,53.0, 4..

~ .:<".r; ~...; - ~..; ."....

~ ~ ~ .. - ~

Kobayaahi; !ogtefseM.50 M-2.08.

' uv s i '

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e 100 z 50 0 20 a0 60 80 100 120 Time iseet Fig.B Fluctuation. of acceleration during an earthquake: Tokachioki earthquake, May 16, 1968; M=7.9, recorded at Hachinohe harbor, d =180 km.

1315

UNIFORM HAZARD SPECTRA FOR THE ST. LUCIE AND TURKEY POINT NUCLEAR POWER PLANTS Figures 1 through 6 show Uniform Hazard Spectra (constant annual probability of exceedance) developed using the approved Electric Power Research Institute (EPRI) methodology. Figures 4 through 6 are smoothed versions of Figures 1 through 3.

The NRC's Safety Goal Policy provides a performance objective, at Level 4, of 1 x 10 mean frequency of core damage. Plant equipment seismic ruggedness customarily contributes at least an order of magnitude, resulting in a reasonable value for mean frecpency for a safety guideline for seismic core damage being 1 x 10 it If is hypothesized that plant equipment seismic ruggedness contributes nothing, then the mean frequency of core damage given an earthquake is the same as the mean frequency of the occurrence of the earthquake, and a "worst case" scenario is created.

As can be seen from Figures 1 through 6, even under this "worst case" scenario, all of FPL's Uniform Hazard Spectra at both the mean and the 85th percentile are bounded by the Housner and Reg.

Guide 1.60 spectra anchored at 0.1g, the legal minimum permitted by 10 CFR 100.

The (safe shutdown) Housner spectra for St. Lucie Unit 1 are presently anchored at 0.1g and the Housner spectra for Turkey Point are presently anchored at 0.15g. It is FPL's intention to relicense Turkey Point to a Safe Shutdown Earthquake of 0.10g in the coming year.

In the Regulatory analysis for A-46 (NUREG-1211) a probability of 2.5 x 10 'as chosen by the NRC. The closest, more conservative, probability available to FPL using the EPRI Uniform Hazard Spectra methodology was 2 x 10 'nd Figures 1 through 6 also provide mean and 85th percentile spectra at this probability for comparative purposes. As can be seen, significant additional seismic margin exists at this probability.

From the foregoing two examples FPL's plants, if it can be concluded that all of designed to Housner or Reg. Guide 1.60 spectra anchored at the legal minimum of 0.1g, clearly have the Safe Shutdown Earthquake design capacity needed to meet the NRC's performance objective of mean frequency of core damage, an objective beyond current licensing basis, without having to take credit for any earthquake resistance offered by any plant systems, NUREG-1211 probability of 2.5 x 10 'n structures, or equipment. It can be further concluded that at the which the Regulatory Analysis for A-46 is based, that significant additional seismic margin exists.

0'. 3 ST. LUC IE

~ 0.2 Housner Spec.

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Rorlda Power and Light Com y EBASCO SERVICES INCORPORATED Uniform Hazard Spectra St. Lucia Unit 1;EIGURE g

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!Florida'Power and Light Companyl

'EBASCO SERVICES INCORPORATED Uniform Haiard Spectra St. LUcle Ugit 2~FIGOR'E 2

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Florida Power and. Ught Company EBASCO SERVICES INCORPORATEQ Uniform Hazard SpectraI Turkey Point Units 3/4'FIGURE 3

0.3 ST. LUCIE Housner Spec, 1.0E-04

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Lucie Unit 1 yIGORE 4

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EBASCO SERVICES INCORPORATED I ISmo'othed Uniform Hazard Spectra'I

St. Lucle Unit 2 FIGURE 5

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Florida Power and Ught Company EBASCO SERV(CES INCORPGRATED Smoothed Uniform Hazard Spectra Turkey Point Units.3/4 ";FlGORE 6

PROBABILISTIC SEISMIC HAZARD EVALUATION AND UNIFORM HAZARD SPECTRA St. Lucie and Turkey Point Nuclear Power Plant Sites FLORIDA Executive Summary prepared for the Florida Power & Light Company Nuclear Licensing Department n

December 1989 EBASCO EBASCO SERVICES INCORPORATED Greensboro, N.C.

1. Introduction As a result of the unresolved questions regarding the cause and source of seismicity in the region of the United States east of 105'%ongitude (Eastern U.S.), the U.S. Nuclear Regulatory Commission (NRC) is actively pursuing the use of probabilistic methods, as alternatives to the determnustic methods used in the past, to determine the adequacy of the seismic design of nuclear facilities in the Eastern U.S. The methodology takes into account the uncertainties in source geometry, seismicity parameters and ground motion for large earthquakes that could occur in the Eastern U.S. As part of the NRC-funded investigations, the Lawrence Livermore National Laboratory (LL'NL) initially conducted probabilistic seismic hazard evaluations for ten "sample sites" whose locations are shown on Figure 1.

it published an eight volume report on seismic hazard characterization of 69 'ecently nuclear plant sites east of the Rocky Mountains, and presented comparisons to previous-results for ten test sites (Bernreuter et al., 1989). A parallel probabilistic seismic hazard study, based on an intensive data collection and evaluation effort, was implemented by the Electric Power Research Institute (EPRI) (1986-87) with the assistance of six Technical Evaluation Contractors (TEC). Both the NRC-funded LLNL studies, and the EPRI investigations, funded by a group of nuclear power plant owners in the Eastern U.S., utilize comprehensive seismic and tectonic data bases and recent advances in the probabilistic methodologies to perform a state-of-the-art seismic hazard evaluation for sites located in the Eastern U.S.

In light of these recent advances in probabilistic seismic risk assessment, the Florida Power and Light Company (FP&L), Nuclear Licensing Department requested that Ebasco Services Incorporated (ESI) perform a state-of-the-art seismic hazard evaluation for its St. Lucie and Turkey Point nuclear power plant sites and generate the associated uniform hazard spectra for comparison purposes. The evaluation was performed 'under the Quality Assurance requirements of 10 CFR 50 Appendix B, and used the methodology, computer programs, and the tectonic and seismic input parameters developed as a result of the EPRI

investigations. In addition, the scope of the ESI investigation included an evaluation of the contribution to seismic hazard at the St. Lucie and Turkey Point sites from the possible'ccurrence of large magnitude earthquakes in the Northern Caribbean.

2. Procedure Following the EPRI methodology, the seismic hazards and uniform hazard spectra were computed for the St. Lucie and Turkey Point sites using the seismic source zones and seismicity parameters established by each of the six EPRI Technical Evaluation Contractors (TEC), and the seismic source zones,and seismicity parameters identiQed by ESI for the Northern Caribbean. The'location and extent of the seismic source zones that were evaluated in this study are shown on Figures 2 through 8.'he source zones that contributed to the seismic hazard at each of the two plant sites have also been listed on these Qgures. The TEC source zone names, labels, and the EPRI Data Base Manager code numbers are given in Table 1. Two of the Northern Caribbean sources, Cayman Trough and Jamaica-Western Hispaniola, that were identiQed during this study contributed to the seismic hazard at Turkey Point, but contributed to the hazard at St. Lucie for pseudo relativ'e velocities at frequencies 5 hz and less only. Also contributions of New Madrid area sources to the seismic hazard at both plant sites for each of the six TECs were found to be negligible; The scenarios and weights for the source zones that contributed to seismic hazard at St. Lucie and Turkey Point sites are given in Tables 2 and 3, respectively. The seismic hazard values that were calculated from each TEC model were then aggregated in accordance with the EPRI methodology to generate the Qnal hazard curves.

Site speciQc, frequency and amplitude dependent, amplification factors were used in the hazard computation as specified by the EPRI methodology (Toro, McGuire and Silva, 1988, and Toro,-McGuire and McCann, 1989).

Hazard curves for pseudo relative velocities at different frequencies were used to derive constant percentile and mean uniform hazard spectra (UHS), at various speciQed risk levels.

3. Results The mean and 15th, 50th, and 85th percentile hazard, in terms of annual probabilities of exceedance, for different peak'ground accelerations at the St. Lucie site are shown in Table
4. The results for the St. Lucie site are presented as constant percentile hazard curves on Figure 9 for peak ground acceleration. On this Ggure the 15th, 50th, and 85th percentile curves represent the aggregated results of all TECs. The mean hazard curve is shown by a dashed line. Sensitivity of hazard results to dif'ferent earth science teams is shown in Figure 10 by plotting the 50th percentile hazard curve of each TEC prior to aggregation.

For reference, Figure 10 also includes the mean and 85th, 50th, and 15th percentile curves aggregated over all teams.

Figures 11 through 15 show uniform hazard spectrum plots for annual exceedance probabilities of 1.0E-05, 1.0E-04, 2.0E-04, 1.0E-03 and 2.0E-03, each showing the 15th, 50th, and 85th percentile uniform hazard spectra. Figure 16 is a uniform hazard spectrum plot, showing mean spectra for annual exceedance probabilities of 1.0E-05, 1.0E-04, 2.0E-04, 1.0E-03 and 2.0E-03.

Seismic hazard results for the Turkey Point site are presented on Table 5. In the same sequence as for St. Lucie, the hazard curves for peak ground acceleration and uniform hazard spectra for the Turkey Point site are shown on Figures 17 through 24.

The annual probability of exceedance and the corresponding return periods for the 50th percentile hazard at various levels of peak ground acceleration for the St. Lucie and Turkey Point sites are given in Tables 6 and 7; respectively, and for the 85th percentile hazard in

~ Tables 8 anti 9, respectively.

4. Summary and Conclusions As one would expect from a general observation of seisinicity of the Florida peninsula, within the context of the Eastern U.S. seismicity as seen on an epicenter map, the level of seismic hazard at St. Lucie and Turkey Point sites is very low. Most of the contribution to the hazard at the two sites, for each of the earth science teams, comes from the background source containing the site. Background sources have been characteristically assigned low maximum magnitudes by all TEC teams in comparison to other sources in the eastern U.S.

It was also noted that distant sources making contribution to the hazard at the two sites for low frequency ground motion make less contribution at the sites for high frequency ground motion. It appears that the high frequency components of ground motion attenuate at a more rapid rate with distance than lower frequency components. Thus some distant sources whose contribution was negligible in the computation of high frequency 'ground motion, were included in the computation of total annual probability of exceedance.

In summary, the results of the probabilistic seismic hazard evaluation for Florida Power and Light's St. Lucie and Turkey Point sites, using the EPRI methodology, yield very low values for each site's seismic hazard.

4

~ 5. Bibliography Bernreuter, D.L, J.B. Savy, R.W. Mensing and J.C. Chen (1989). "Seismic Hazard Characterization of 69 Nuclear Power Plant Sites East of the Rocky Mountains",

Volumes 1-8, U.S. Nuclear Regulatory Commission, NUREG/CR-5250, UCID-21517.

Electric Power Research Institute (1986-87). "Seismic Hazard Methodology for the Central and Eastern United States", Volumes 1-10, Palo Alto, CA, EPRI NP-4726.

Toro, G.R., R.K. McGuire and W3. Silva (1988). "Engineering Model of Earthquake Ground Motion for Eastern North America", Electric Power Research Institute, Palo Alto, CA, EPRI NP-6074, Research Project 2556-16.

Toro, G.R., R.K. McGuire and M.W. McCann (1989). "EQHAZAIU) Primer", Electric Power Research Institute, Palo Alto, CA; EPRI NP-6452-D, Research Projec't P101-

~

46.

e TABLE 1 Computerized Data Base Label No. of Source Zones TEC Name TEC Label No. Source Name Data Base Label No.

(Used on TEC Maps) (Used on Computer Files)

Bechtel Group 13 Mesozoic Basins 01300 30 New Madrid 03000 31 Reelfoot Rift 03100 H Charleston Area 05200 N-3 Charleston Faults 05900 BZ-0 New Madrid Region 00100 BZ-1 Gulf Coast Background 00600 BZ-4 Atlantic Coast Background 02000 Dames &; Moore 20 Southern Coastal Margin 02000 21 New Madrid 02100 22 Reelfoot Rift 02200 22-21B Reelfoot Rift-New Madrid 91500 52 Charleston Rift 05200 53 Southern Appalachian Default 05300 54 Charleston Seismic Zone 05400 65 Dunbarton Triassic Basin 06500 Law Engineering 04a Reelfoot Rif't(A) 00401 04b Reelfoot Rift(B) 00402 22 Reactivated Eastern Seaboard 02200 08 Mesozoic Basins 00816 18'5 Reelfoot Rift Faults 01800 Charleston 03500 108 Brunswick Background 04300 126 Southern Coastal Block 06001 M-37 MaGc Pluton 03837 M-38 MaGc Pluton 03838 M-39 MaGc Pluton 03839 M-40 MaGc Pluton 03840 M41 MaGc Pluton 03841 M-42 MaGc Pluton 03842 M-43 MaGc Pluton 03843 M-44 MaGc Pluton 03844 M45 MaGc Pluton 03845 M48 MaGc Pluton 03848 M-49 MaGc Pluton 03849 M-50 MaGc Pluton 03850 Table 1 - continued

TABLE 1 (Continued)

Computerized Data Base Label No. of Source Zones TEC Name TEC Label No. Source Name Data Base Label No.

(Used on TEC Maps) (Used on Computer Files)

Rondout Associates 1 New Madrid 00100 2 New Madrid Rift 00200 24 Charleston 02400 26 South Carolina 02600 49-05 Appalachian Basement 04905

Background

51 Gulf Coast to Bahamas 05100

Background

Weston Geophysical 25 Charleston 02500 26 South Carolina 02600 31 New Madrid 03100 32 Reelfoot Rift 03200 104 Southern Coastal Plain 05400

Background

107 Gulf Coast Background 05700 Z032-Z031 Combination (C-11) 91100 Z104-Z022 Combination (C-20) 92000 Z104-Z025 Combination (C-21) 92100 Z104-Z026 Combination (C-22) 92200 Z104-Z022 Combination (C-23) 92300

-Z026 Z104-Z022 Combination (C-24) 92400

-Z025 Z104 Combination (C-27) 92700

-Z028BCDE

-Z022-Z025 Z104 Combination (C-28) 92800

-Z028BCDE

-Z022-Z026 Woo dward-Clyde 1 Continental Shelf. Edge 00100 29 SC Gravity Saddle (extended) 02900 29A SC Gravity Saddle P2 0290A 30 Charleston NOTA 03000 40 Central Reelfoot Rift 04000 41 Combination (C-8) 90800 44 New Madrid Loading Zone 04400

TABLE 2 Scenarios for Contributing Source Zones't.

Lucie (frequencies greater than Shz)

TE Team ~cenario hei sf'.05 Bechtel 00600 + 02000 + 01300 + 05200

, 00600 + 02000 + 01300 0.05 00600 + 02000 + 05200 0.45 00600 + 02000 0.45 Background 00600 1.0 02000 1.0 Dames aod Moore 02000 + 05400 0.28 02000 + 05400 + 05200 0.46 02000 + 05400 + 05300 0.26 Background , 02000 1.0 Law Engineering 04300 + 06001 + 02200 0.27 04300 + 06001 + 00816 0.27 04300 + 06001 0.46 Background 04300 0.42 06001 0.49 Rondout Associates 02400 + 02600 + 04905 + 05100 1.0 Background 04905 1.0 05100 1.0 Weston Geophysical 05700 + 92000 0.001 Corporation 05700 + 02500 + 92100 0.012 05700 + 02600 + 92200 0.069 05700 + 02600 + 92300 0.312 05700 + 02500 + 92400 0.368 05700 + 02500 + 92700 0.126 05700 + 02600 + 92800 0.100 05700 + 05400 0.012 Background 05700 1.0 Woodward Clyde WCCBK 0573 Consultants WCCBK + 02900 0.122 WCCBK + 0290A 0.305 Background WCCBK 1.0 Table 2 - continued

i e

f ~

TABLE 2 (continued)

Scenarios for Contributing Source Zones St. Lucie (frequencies Shz and less)

T~ETeam Q:ena~ri ) hei yet Bechtel 00600 + 02000 + 01300 + 05200 0.05

+ CB001 + CB002 00600 + 02000 + 01300 + CB001 + CB002 0.05 00600 + 02000 + 05200 + CB001 + CB002 0.45 00600 + 02000 + CB001 + CB002 0.45 Background 00600 1.0 02000 1.0 Dames and Moore 02000 + 05400 + CB001 + CB002 0.28 02000 + 05400 + 05200 +,. CB001 + CB002 0.46 02000 + 05400 + 05300 + CB001 + CB002 0.26 Background 02000 1.0 Law Engineering 04300 + 06001 + 02200 + CB001 + CB002 0.2700, 04300 + 06001 + 00816 + 03842 + 03848 0.1161

+ 03849 + 03850 + CB001 + CB002 04300 + 06001 + 00816 + CB001 + CB002 0.1539 04300 + 06001 + 03842 + 03848 + 03849 0.1978

+ 03850 + CB001 + CB002 04300 + 06001 + CB001 + CB002 0.2622 Background 04300 0.42 06001 0.49 Rondout Associates 02400 + 02600 + 04905 + 05100 1.0

+ CB001 + CB002 Background 04905 1.0 05100 1.0

~ Westoo Geophysical Corporation 05700 05700

+

+

92000 02500

+

+

CB001 + CB002 92100 + CB001 + CB002 0.001 0.012 05700 + 02600 + 92200 + CB001 + CB002 0.069 05700 + 02600 + 92300 + CB001 + CB002 0.312 05700 + 02500 + 92400 + CB001 + CB002 0368 05700 + 02500 + 92700 + CB001 + CB002 0.126 05700 + 02600 + 92800 + CB001 + CB002 0.100 05700 + 05400 + CB001 + CB002 0.012 Background 05700 1.0 Table 2 - continued

TABLE 2 (continued)

Scenarios for Contributing Source Zones't.

Lucie (frequencies 5hz and less)

T~ETeam Scenario heit Woodward Clyde WCCBK + CB001 + CB002 0.573 Consultants WCCBK + 02900 + CB001 + CB002 0.122 WCCBK + 0290A + CB001 + CB002 0.305 Background WCCBK 1.0 Notes: Source Zone numbers correspond to those ou Table 1 and on Figures 2 through 7.

2 Each TEC scenario is made up of the allowable source zone combinations whose total weights, or probability of activity add up to 1.0.

~

Weight is defined as the fractional probability of activity.

TABLE 3 Scenarios for Contributing Source Point (frequencies greater than 5hz)

Zones'urkey TE Team Qen~ari ~Wei r Bechtel 00600 + 02000 + CB001 + CB002 1.0 Background 00600 1.0 02000 1.0 Dames and Moore 02000 + CB001 + CB002 1.0

~ Inw Engineering 04300 + 06001 + 02200 + CB001 + CB002 04300 + 06001 + 00816 + CB001 + CB002 0.27 0.27 04300 + 06001 + CB001 + CB002 0.46 Background 04300 0.42 06001 0.49 Rondout Associates 04905 + 05100 + CB001 + CB002 1.0 Background 04905 1.0 05100 1.0 Weston Geophysical 05700 + 'CB001 + CB002 1.0 Corporation Background 05700 1.0 Woodward Clyde WCCBK + CB001 + CB002 1.0 Consultants Background WCCBK 1.0 Table 3 - continued

TABLE 3 (continued)

Scenarios for Contributing Source Point (frequencies Shz and less)

Zones'urkey T~ETeam Qcen~ri~y2 ~Wei Bechtel 00600 + 02000 + CB001 + CB002 1.0 Background 00600 1.0 02000 1.0 Dames and Moore 02000 + 05400 + CB001 + CB002 0.28 02000 + 05400 + 05200 + CB001 + CB002 0.46 e 02000 + 05400 + 05300 + CB001 + CB002 0.26 Law Engineering 04300 + 06001 + 02200 + CB001 + CB002 0.2700 04300 + 06001 + 00816 + 03842 + 03848 0.1161

+,CB001 + CB002 04300 + 06001 + 00816 + CB001 + CB002 0.1539 04300 + 06001 + 03842 + 03848 0.1978

+ CB001 + CB002 04300 + 06001 + CB001 + CB002 0.2622 Background 04300 0.42 06001 0.49 e Rondont Associates 02400 + 02600 + 04905 + 05100

+ CB001 + CB002 1.0 Background 04905 1.0 05100 1.0 Weston Geophysical 05700 + 92000 + CB001 + CB002 0.001 Corporation 05700 + 02500 + 92100 + CB001 + CB002 0.012 05700 + 02600 + 92200 + CB001 + CB002 0.069 05700 + 02600 + 92300 + CB001 + CB002 0.312 05700 + 02500 + 92400 + CB001 + CB002 0.368 05700 + 02500 + 92700 + CB001 + CB002 0.126 05700 + 02600 + 92800 + CB001 + CB002 0.100 05700 + 05400 + CB001 + CB002 '.012

'ackground 05700 1.0 Table 3 - continued

TABLE 3 (continued)

Scenarios for Contributing Source Point (frequencies Shz and less)

Zones'urkey T~ETeam ~ceaari ~Wi >t Woodward Clyde WCCBK + CB001 + CB002 0.573 Consultants WCCBK + 02900 + CB001 + CB002 0.122 WCCBK + 0290A + CB001 + CB002 0.305 Background WCCBK 1.0 Notes: Source Zone numbers correspond to those on Table 1 and on Figures 2 through 7.

Each TEC scenario is made up of the allowable source zone combinations whose total weights, or probability of activity add up to 1.0.

~

Weight is defined as the fractional probability of activity.

TABLE 4 Sc, Lucie Annual Probability of Exceedaace for Peak Ground Acceleration (PGA)

Mean Percenciles PQA PGA 15 50 85 (cm/sec ) (8) 7.00 0.007 7.36E-04 1.82E-05 4,97E-04 1.608-03 65.00 0.07 3.89E-05 7.80E-07 3,15E-05 6.84E-05 120.00 0.12 1.24E-05 2,008-07 1.05E-05 2.29E-05 225.00 0 '3 1.61E-06 1.40E-OS 1.048-06 2.75E-06 400,00 0.41 1.78E-07 5.82E-10 7.48E-OB 3.08E-07 560 00 F 0.57 5.08E-08 1.97E-10 1.32E-OS 8.60E-08 800.00 0 '2 1.22E-OS 1,.91E-10 1.51E-09 1.41E-08 TABLE 5 Turkey Point Annual Probability of Exceedance for Peak Ground Acceleration (PGA)

Mean Percentiles PGA PGA 15 50 85 (cm/sec2) (g) 5 OP 0.005 3.90E-03 1 '2E-04 3,27E-04 1.34E-02 50.00 0.05 3.18E-05 7.89E-07 2.75E-05 5.61E-05 100.00 0,10 1.08E-05 1.87E-07 9.57E-06 2.02E-05 250.00 0.26 1.39E-06 1.29E-08 9.19E-07 2.58E-06 500.00 0,51 1.52E-07 7.26E-10 5,95E-OS 2.85E-07 700.00 0.71 4.33E-08'.04E-08

3. 91E-10 9,89E-09 7.16E-08 1000.00 1,02 3.91E-10 1.17E-09 1.21E-OS 4< ~ ~

TABLE 6 Peak Ground Acceleration (PGA)

Annual Probability of Exceedance and Return Periods Seismic Hazard Results Summary for St. Lucie Site 50th Percentile Acceleration Annual Probability Estimated Return (g) of Exceedance, Period (yrs) 0.007 4.97E-04 2,012 0.07 3.15E-05 31,746 0.12 1..05E-05 95,238 0.23 1.04E-06 961,538 0.41 7.48E-08 13,368,984 0.57 1.32E-08 75,757,576 0.82 1.51E-09 662,251,655 TABLE 7 Peak Ground Acceleration (PGA)

Annual Probability of Exceedance 'and Return Periods Seismic Hazard Results Summary for Turkey Point Site 50th Percentile Acceleration Annual Probability Estimated Return (g) of Exceedance Period (yrs) 0.005 3.27E-04 3,058 0 '5 2.75E-05 36,364 0.10 9.57E-06 104,493 0.26 9 '9E-07 1,088,139 0.51 5,95E-08 16,806,723 0.71 9.89E-09 101,112,234 1.02 1.17E-09 854,700,854

e TABLE 8 Peak Ground Acceleration (PGA)

Annual Probability of Exceedance and Return Periods Seismic Hazard Results Summary for St. Lucie Site 85th Percentile Acceler'ation Annual Probability Estimated Return (s) of Exceedance Period (yrs) 0.007 1.60E-03 625 0.07 6.84E-05 14,620 0.12 2.29E-05 43,668 0.23 2.75E-06 363,636 0.41 3.08E-07 3,246,753 0.57 8.60E-08 11,627,907 0.82 1.41E-08 70,921,986 TABLE 9 Peak Ground Acceleration (PGA)

Annual Probability of Exceedance and Return Periods Seismic Hazard Results Summary for Turkey Point Site 85th Percentile Acceleration Annual Probability Estimated Return (s) of Exceedance Period (yrs) 0.005 1.34E-02 75 0.05 5.61E-05 17,825 0.10 2.02E-05 49,505 0.26 2.58E-06 387,597 0.51 2.85E-07 3,508,772 0.71 7.16E-08 13,966,480 1.02 1.21E-08 82,644,628

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10. Maine Yankee EBASCO SERVICES IKCORPORATEG Location of the LLNLSample Sites and St. Lvcie and Turkey Point FIGURE- 1

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Sr. Lucre Tvrke Poinr Source Zone Source Zone Contributing to Hazard Number I ~ =me St. Lucie Turkey Point 01300 ,

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05200 Charleston A.ea 05200 05900 Charleston Faults 00100. New Madrid Background 00600 53te Background 00600 02000 Adjacent Background 02000 02000 Florida Power and light ComPany EBASCO SERVICES INCORPORATEO Seismic Source Zones Considesed ror the Florida Power and L~t Comr3eny I8ech tel Gr inc. 10todet Fl 2

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05200 l 02000 Sr. Lucle Turkey Poinr Note: 0540D is Default Zone for 05400 Source Zone Source Zone Contributing to Hazard Number Kame St. Lucie Turkey Point 02000 Southern Coastal Margin 02000 02000 02100 Ne;y Madrid I ~ 02200 05200 05300 Iteelfoot Rift Charleston Rift Southern Appalachian Default 05200 05300 052K 053QQ 05400 Charleston Seismic Zone 05400 05400 0540D Charleston Default Zone 0540D 0540D 06200 Dunbar ton Triassic Basin NOTE: THE UNDERLINED SOURCES CONTRIBUTE TO LOW FREQUENCY (5hz AND LESS/ GROUND NOTION Florida power and Light Company EBASCO SERVICES INCORPORATED Seismic Source Zones Considered or the Florida Power and Light Company IOames and Moore Model)

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/ 038.48 038.50 06001 Sr. Lucia Turke Po/nr Source Zone Source Zone Contributing to Hazard Number Name St. Lucie Turkey Point 00401 Reelfoot R itt (Al t

00402 ~ Reel foot R i(t I B) 00816 Mesozoic Basins 00816 00816 01800 Reeltoot Rift Faults 02200 Reactivated Eastern Seaboard 02200 02200 03500 Charleston 04300 ~ Brunswick 04300 04300 06001 Southern Coastal Block 06001 06001 03837 Mafic Plutons to 03845 03848 Mafic Plutons to Florida Power and Light Company 03850 EBASCO SERVICES INCORPORATED NOTE: THE UNDERLINED SOURCES CONTRIBUTE TO LOW FREQUENCY . Seismic Source Zones Considered for the Florida Power and Light Company (5hz AND LESSJ GROUND MOTION ILaw Engineering Company Modell FIGURE 4

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I 04905 05100 Sr. Lucie Turkey Poinr Source Zone Source Zone Contributing to Hazard Number Name St. Lucie Turkey Point 00100 New Madrid 00200 New Madric R:lt 02400 Charleston 02400 Q2400 02600 South Carolina 02600 02600 04905 Appalachian Basement Background 04905 04905 05100- Gulf Coast to Bahamas Background 05100 05100 NOTE: THE UNDERLINED SOURCES CONTRIBUTE TO LOW FREQUENCY

'(5hz AND LESSI GROUND NOTION Florida Power and Light Company

.EBASCO SERVICES INCORPORATEO Seismic Source Zones Considered for the Florida Power and Light Company Rondout Associates Model FIGURE 6

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05700 Sr. Lvcie Tvrkey Poinr Source Zone Source Zone Contributin to Hazard Number Name St. Lucie T~urke Point 02500 Charleston 02500 0~25 02600 South Carolina 02600 02600 03100 New Madrid 03200 Reelfoot Rift 05400 Southern Coastal Plain 05400 KKQ 05700 Gulf Coast Background 05700 05700 91100 Combination 11 92000'to Combinations 92000 92600 920 to 924 to 92400 92400 92400'2700 Combination 927 92700 ~7 92800 Combination 928 92800 S2999 Geometry ot Combination Sources Given in Table l. Florida Power and Light CompanY EBASCO SERVICES INCORPORATEO NOTE: THE UNDERLINED SOURCES CONTRIBUTE TO LOW FREQUENCY Seismic Source Zones Considered Ior (5hz AND LESS/ GROUND NOTION the Florida Power and Light Comoanv IINeston Gecohvsical Coro. Modeil FIGURE 6

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'eismic Source Zones Considered for the Florida Power and Light Company in the Northern Caribbean FIGURE 8

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HAZARD RESULTS AT ST. LUCIE ALL EXPERT TEAMS 10 Bechtel Dames and Moore 0 85th Percentile Law Engineering X 50th Percentile 10 Rondout Associates 15th Percentile Weston Geophysical + Mean Hazard Woodward Clyde Consultant All Expert Teams 10' Z:

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Flotlda povier and Light Company EBASCO SERViCES INCORPORATEO FIGURE 10

Uniform Hazard Spectra (Annual Probability of Exceedance 1.0E-05) 100 ST. LUCIE 85 10 LLI V) 50 O

15 C3

-0 1 LLI 0.1 0.01 0.1 10 PERIOD (SEC)

Florida Power and Light Company EBASCO SERVICES INCORPORATEO FIGURE 11

Uniform Hazard Spectra (Annual Probability of Exceedance 1.0E 04) 100 ST. LUCIE 10 V)

C3 50 I 15 C3

~

0 LLJ 0.1 0.01 0.1 10 PERIOD (SEC)

Fiorida Power and Light Company EBASCO SERVICES INCORPORATEO FIGURE 12

Uniform Hazard Spectra (Annual Probability of Exceedance 2.0E 04) 100 ST. LUCIE 10 V)

C3 50 C3 15 0

LLJ 0.1 0.01 0.1 10 PERIOD (SEC)

Florida Power and Light Company EBASCO SERVICES INCORPORATED FIGURE 13

Uniform Hazard Spectra

{Annual Probability of Exceedance 1.0E-03) 100 ST. LUCIE O 10 LLI 85 C3 0V 1 QJ 0.01 0.1 10 PE:ROOD (SEC)

Fiorida Power and Light Company EBASCO SSRV(CES INCORPORATEO FIGURE 14

Uniform Hazard Spectra (Annual Probability of Exceedance 2.0E 03) 100 ST. LUCIE 10 V) 85 C3 V

0 LLI g 50 0.1 0.01 0.1 10 PERIOD (SEC)

Florida Power and Light Company EBASCO SERVICES INCORPORATED FIGURE 15

Mean Uniform Hazard Spectra ST. LUCIE

-5 1.0E10 1.0E10 a 2.0E 10

-3 1.0E 10

-3 2.0E 10 0.1 10 PERIOD (SEC)

Florirla Power and Light Company EBASCO SERVICES INCORPORATED FIGURE 16

e HAZARD RESULTS AT TURKEY POINT EQUAL TEAM WEIGHTS 10 a 85th Percentile

-2 50th Percentile 10 15th Percentile

+ Mean Hazard l1

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Florida Power and Light Company EBASCO SERVICES INCORPORATED FIGURE 17

HAZARD RESULTS AT TURKEY POINT ALL EXPERT TEAMS 10 Bechtel Dames and Moore O 85th Percentile Law Engineering X 50th Percentile 10 Rondout Associates 15th Percentile Weston Geophysical + Mean Hazard Woodward Clyde Consultant All Expert Teams 10 O

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Florida Power and Light Company

" EBASCO SERVICES INCORPORATEO FIGURE 18

0 Uniform Hazard Spectra (Annual Probability of Exceedance 1.0E-05) 100 TURKEY POINT 10 '85 LLj

(/)

C3 15 C3 0

Ld 0.1 0.01 0.1 10 PERIOD (SEC)

Florida Power and Light Company EBASCO SERVICES INCORPORATEO FIGURE 19

Uniform Hazard Spectra (Annual Probability of Exceedance 1.0E-04) 100 TURKEY POINT O 10 V)

C3 50 C3 0 1 IJJ 0.1 0.01 0.1 10 PERIOD (SEC)

Florida Power and Light Company EBASCO SERVICES INCORPORATEO FIGURE 20

0 Uniform Hazard Spectra (Annual Probability of Exceedance 2.0E 04) 100 TURKEY POINT 10 V) 85 V

C3 0 1 LLI 0.01 0.1 10 PERIOD (SEC)

Florida Powar and Light Company EBASCO SERVICES INCORPORATEO FIGURE 21

Uniform Hazard Spectra (Annual Probability of Exceedance 1.0E 03) 100 TURKEY POINT V

LLj 10 V)

.O 85 C3 0 1 50 bJ 0.1 0.01 0.1 10 PERIOD (SEC)

Florida Power and Light Company EBASCO SERVICES INCORPORATEO FIGURE 22

Uniform Hazard Spectra (Annual Probability of Exceedance 2.0E 03) 100 TURKEY POINT O 10 LLI V)

O 85 C3 0, 1 50 LLI 0.1 0.01 0.1 10 PERIOD (SEC)

Florida Power and Light Company EBASCO SERVICES INCORPORATEO FIGURE 23

0 Mean Uniform Hazard Spectra 100 TURKEY POINT

-5 O 10 1.0410 V) 1.0<<10 4 2.0<<10

-3 O 1.04 10

-3 2.04 10 0C3 LLj 0.1 0.01 0.1 10 PERIOD (SEC)

Florida Power and Light Company EBASCO SERV1CES INCORPORATEO FIGURE 24