UNITED STATES NUCLEAR REGULATORY COMMISSION · Monterey, CA 93940 Ed Bailey, Radiation Control Program Director Radiologic Health Branch State Department of Health Services P.O. Box

UNITED STATES

NUCLEAR REGULATORY COMMISSIONREGION IV

611 RYAN PLAZA DRIVE, SUITE 4006' ARLINGTON, TEXAS 76011-4005

February 13, 2004

Gregory M. Rueger, Senior VicePresident, Generation and Chief Nuclear OfficerPacific Gas and Electric CompanyDiablo Canyon Power PlantP.O. Box 3Avila Beach, California 93424

SUBJECT: MEETING SUMMARY FOR THE TWO FEBRUARY 4, 2004, PUBLICMEETINGS

Dear Mr. Rueger:

This refers to the two public meetings conducted at the Embassy Suites Hotel in San LuisObispo, California, on February 4, 2004. The first meeting was a technical meeting to discussthe results of the Special Report submitted following the December 22, 2003, earthquake nearSan Simeon, California. During the second meeting NRC provided a detailed interim exit of anNRC inspection conducted following the December 22 earthquake. The meeting attendance listand a copy of the material discussed during the meeting are enclosed. The meeting wastranscribed and the transcript will be provided at a later date. The NRC will review the transcriptto ensure that questions raised during the meeting are adequately addressed.

In accordance with Section 2.790 of the NRC's "Rules of Practice," Part 2, Title 10, Code ofFederal Regulations, a copy of this letter and its enclosure will be available electronically forpublic inspection in the NRC's Public Document Room or from the Publicly AvailableRecords (PARS) component of NRC's document system (ADAMS). ADAMS is accessible fromthe NRC Web site at httR://www.nrc.gov/reading-rm/adams/index.html (the Public ElectronicReading Room).

Should you have any questions concerning this matter, we will be pleased to discuss them withyou.

Sincerely,

William B. Jones, ChiefProject Branch EDivision of Reactor Projects

Dockets: 50-27550-323

License: DPR-80DPR-82

Pacific Gas and Electric Company -2-

Enclosures:1. Attendance List2. Background Information3. Excerpts for NRC Integration Inspection Report 05000275/2003008 and 05000323/20030084. Preliminary Result of NRC Event Followup for the December 22, 2003, San SimeonEarthquake5. Preliminary Report on December 22, 2003, San Simeon Earthquake6. Special Report 03-03: Seismic Event of October 18, 20037. Special Report 03-04: San Simeon Earthquake of December 22, 20038. PG&E Presentation

cc w/enclosures:David H. Oatley, Vice President

and General ManagerDiablo Canyon Power PlantP.O. Box 56Avila Beach, CA 93424

Lawrence F. Womack, Vice President, PowerGeneration & Nuclear Services

Diablo Canyon Power PlantP.O. Box 56Avila Beach, CA 93424

James R. Becker, Vice PresidentDiablo Canyon Operations andStation Director, Pacific Gas andElectric Company


Sierra Club San Lucia Chapterc/o Henriette Groot1000 Montecito Rd.Cayucos, CA 93430

Nancy CulverSan Luis Obispo Mothers for PeaceP.O. Box 164Pismo Beach, CA 93448

ChairmanSan Luis Obispo County Board ofSupervisors

Room 370County Government CenterSan Luis Obispo, CA 93408


Truman Burns\Robert KinosianCalifornia Public Utilities Commission505 Van Ness Ave., Rm. 4102San Francisco, CA 94102-3298

Diablo Canyon Independent Safety CommitteeRobert R. Wellington, Esq.Legal Counsel857 Cass Street, Suite DMonterey, CA 93940

Ed Bailey, Radiation Control Program DirectorRadiologic Health BranchState Department of Health ServicesP.O. Box 942732 (MS 178)Sacramento, CA 94234-7320

Richard F. Locke, Esq.Pacific Gas and Electric CompanyP.O. Box 7442San Francisco, CA 94120

City EditorThe Tribune3825 South Higuera StreetP.O. Box 112San Luis Obispo, CA 93406-0112

James D. Boyd, CommissionerCalifornia Energy Commission1516 Ninth Street (MS 34)Sacramento, CA 95814

Enclosure 1

Earthauake Soecial Report/Interim Exit Public Meeting Attendance

LICENSEE/FACILITY Pacific Gas and Electric Company (PG&E)Diablo Canyon Power Plant

DATE/TIME February 4, 20046:30 p.m.

LOCATION Embassy Suites Hotel

NAME (PLEASE PRINT) ORGANIZATION CATEGORY 1 CATEGORY 3

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Earthauake SDecial ReDort/interim Exit Public Meeting Attendance

LICENSEE/FACILITY Pacific Gas and Electric Company (PG&E)Diablo Canyon Power Plant

DATE/TIME February 4, 20046:30 p.m.

LOCATION Embassy Suites Hotel

NAME (PLEASE PRINT) ORGANIZATION CATEGORY 1CATEGORY 3

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Enclosure 2

BACKGROUNDINFORMATION FOR

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February 4, 20046:30 pm.

Public Meetings

AGENDA

Two separate meetings will be held in regard to the Nuclear Regulatory Commission's

inspection and review of the Diablo Canyon Power Plant response to the San Simeon

earthquake. The first meeting will be a technical meeting (Category 1) to discuss the results of

Pacific Gas and Electric's Special Report submitted following the December 22, 2003,

earthquake near San Simeon, California. Immediately following the technical meeting on the

Special Report, a second meeting (Category 3) will be conducted to provide a detailed interim

exit of an NRC inspection conducted following the December 22, 2003, earthquake.

Category 1 Technical Meeting: The public is invited to observe this meeting and will have one

or more opportunities to communicate with the NRC after the business portion, but before the

meeting is adjourned.

Open meeting at 6:30 pm

* Conduct of Meeting:

* Introductions:

* Introductions:

* Opening Remarks:

* Opening Remarks:

* Discussions:

Nuclear Regulatory Commission


Pacific Gas and Electric Participants


Pacific Gas and Electric

Special Report to December 22, 2003, San Simeon

Earthquake

* Comments and Questions: Meeting attendees

* Adjourn Meeting

Category 3 meeting: The meeting is specifically tailored for the public to comment and ask

questions throughout the meeting.

Open meeting following break

* Conduct of Meeting:

* Introductions:

* Review of Interim Exit Results:

* Questions and Comments:

* Adjourn meeting at 9:30 pm



David Proulx

Meeting Attendees

The NRC staff will make themselves available to

members in the audience following adjournment of

this meeting.

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Earthquake

Enclosure 3

C VUNITED STATESiNUCLEAR REGULATORY COMMISSION

REGION IV-i 611 RYAN PLAZA DRIVE, SUITE 400

ARLINGTON, TEXAS 76011-400

January 30, 2004

Gregory M. Rueger, Senior VicePresident, Generation andChief Nuclear Officer

Pacific Gas and Electric CompanyDiablo Canyon Power PlantP.O. Box 3Avila Beach, CA 93424

SUBJECT: DIABLO CANYON POWER PLANT - NRC INTEGRATED INSPECTIONREPORT 05000275/2003008 AND 05000323/2003008

Dear Mr. Rueger:

On December 31, 2003, the U.S. Nuclear Regulatory Commission completed an inspection at yourDiablo Canyon Power Plant, Units 1 and 2, facility. The enclosed integrated report documents theinspection findings that were discussed on January 8, 2004, with Mr. David H. Oatley andmembers of your staff.

This inspection examined activities conducted under your licenses as they relate to safety andcompliance with the Commission's rules and regulations and with the conditions of your licenses.The inspectors reviewed selected procedures and records, observed activities, and interviewedpersonnel.

There were five findings of very low safety significance (Green) identified in this report. Four ofthe findings were NRC-identified and one was self-revealing. Four of these findings involvedviolations of NRC requirements. However, because of their very low safety risk significance andbecause they are entered into your corrective action program, the NRC is treating these fourfindings as noncited violations (NCVs) consistent with Section Vl.A of the NRC EnforcementPolicy. If you contest any NCV in this report, you should provide a response within 30 days of thedate of this inspection report, with the basis for your denial, to the U.S. Nuclear RegulatoryCommission, ATTN: Document Control Desk, Washington, DC 20555-0001; with copies to theRegional Administrator, U.S. Nuclear Regulatory Commission, Region IV, 611 Ryan Plaza Drive,Suite 400, Arlington, Texas 76011-4005; the Director, Office of Enforcement, U.S. NuclearRegulatory Commission, Washington, DC 20555-0001; and the NRC Resident Inspector at theDiablo Canyon Power Plant.

During the period of December 22, 2003, through January 9, 2004, the NRC has been conductingevent followup inspections at the Diablo Canyon Nuclear Plant in direct response to the December22, 2003, San Simeon earthquake. These event followup inspections continue. The results ofthe inspections conducted through December 31, 2003, (referred to as Phase 1 of the eventfollowup inspections) are documented in the enclosed inspection report (see Section 1 R14). Theresults of the inspection conducted January 1-9, 2004, (referred to as Phase 2 of the event

Pacific Gas and Electric Company -2 -

followup inspections) and additional onsite inspections planned through Unit 1 refueling outage,scheduled to begin in March 2004, (referred to as Phase 3 of the event followup inspections) willbe documented in NRC Inspection Report 05000275;323/2004002, to be issued approximately atthe end of April 2004.

On January 16, 2004, we provided you with some preliminary results of the NRC's event followupfor the December 22, 2003, San Simeon earthquake. (ADAMS Accession ML040160653). Thatletter provided the preliminary results of the inspection activities (Phases 1 and 2) conductedthrough January 9, 2004, and provided the scope for Phase 3 of the NRC's actions that areongoing. The Phase 3 activities will involve additional planned inspections, including the visualinspections in Unit 1 containment during the March 2004 refueling outage and further review ofyour Special Report, submitted to the NRC on January 5, 2004, and any supplemental report.

We plan to conduct a technical meeting with you on February 4, 2004, regarding your January 5,2004, Special Report in San Luis Obispo, California. This meeting will be open to publicobservation and will provide attending members of the public a period for comments and questionsprior to the conclusion of the meeting.

Pacific Gas and Electric Company operated under voluntary bankruptcy proceedings during thisinspection period. The NRC has monitored plant operations, maintenance, and planning to betterunderstand the impact of the financial situation and how it relates to your responsibility to safelyoperate the Diablo Canyon reactors. NRC inspections, to date, have confirmed that you areoperating these reactors safely and that public health and safety is assured.

In accordance with 10 CFR 2.790 of the NRC's "Rules of Practice," a copy of this letter and itsenclosure will be available electronically for public inspection in the NRC Public Document Roomor from the Publicly Available Records System (PARS) component of NRC's documentsystem (ADAMS). ADAMS is accessible from the NRC Web site at http://www.nrc.gov/reading-rm/adams.html (the Public Electronic Reading Room).

Sincerely,

/RA/


Dockets: 50-27550-323

Licenses: DPR-80DPR-82

Enclosure:Inspection Report 05000275/2003008

and 05000323/2003008

SUMMARY OF FINDINGS

IR 05000275/2003-008, 05000323/2003-008; 09/28/03 - 12/31/03; Diablo Canyon Power PlantUnits 1 and 2; Fire Protection, Maintenance Effectiveness, Postmaintenance Testing, ALARAPlanning and Controls, Problem Identification and Resolution.

This report covered a 14-week period of inspection by resident inspectors and announcedinspections in emergency preparedness and radiation protection and followup inspections to theOctober 18 and December 22, 2003, earthquakes. Specifically, Section 1 R1 4.1 documents thefollowup inspections performed in response to earthquakes impacting the Diablo Canyon PowerPlant. The NRC identified four Green noncited violations and one Green finding. Thesignificance of most findings is indicated by their color (Green, White, Yellow, or Red) usingInspection Manual Chapter 0609, "Significance Determination Process." Findings for which theSignificance Determination Process does not apply may be Green or be assigned a severity levelafter NRC management review. The NRC's program for overseeing the safe operation ofcommercial nuclear power reactors is described in NUREG-1 649, "Reactor Oversight Process,"Revision 3, dated July 2000.

A. NRC-Identified and Self-Revealing Findings

Cornerstone: Mitigating Systems

Green. The inspectors identified a violation of Technical Specification 5.4.1.dwhich requires written procedures be established, implemented, and maintainedcovering the Fire Protection Program implementation. Specifically, PG&E failed toadequately establish and implement procedural changes that provided for seniorcontrol operators, licensed control operators, and nonlicensed, Level 8 nuclearoperators to serve in the operator responder position. The inspectors noted thatthe applicable attachment to the procedure for conduct of the operations responseposition was not established until after training had been provided on implementingthe procedure. Operations' responders supporting the fire brigades exhibited aknowledge weakness in activities such as communications with the control room,manual actuation of fire suppression equipment, and providing information to thefire brigade regarding safe shutdown equipment.

The finding impacted the procedure quality objective under the mitigating systemscornerstone and was more than minor since there was an adverse impact to a fireprotection defense-in-depth element. Using the Significance DeterminationProcess (SDP) Phase I Screening Worksheet and the SDP Phase II Notebook inAppendix F of Inspection Manual Chapter (IMC) 0609, the inspectors determinedthat the finding was of very low safety significance. Specifically, the significance ofthe finding was evaluated by considering fire scenarios in the vital 4 kV Bus Fswitchgear room and auxiliary saltwater Pump 1-1 vault. These two areas havethe highest dependence on fire brigade response since they have the highest fireignition frequency for areas that do not have automatic fire suppression. Theinspectors evaluated the risk-significance using half of the nominal credit formanual fire suppression as a result of the finding. Using Tables 5.4, 5.5, and 5.6

Enclosure

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of IMC 0609, both fire scenarios screened as very low safety significance. Sincethe two fire scenarios were considered worst-case for the finding, the inspectorsdetermined that the finding was of very low safety significance (Section 1 R05.2).

Green. The inspectors identified a noncited violation for the failure to adequatelymonitor the performance of the Unit 1 auxiliary feedwater system in accordancewith 10 CFR 50.65(a)(2). Specifically, the unavailability time performance criteriafor the auxiliary feedwater system had been exceeded during its monitoring period,but the system was not monitored per 10 CFR 50.65(a)(1).

The finding impacted the mitigating systems cornerstone objective to ensure theavailability and reliability of the auxiliary feedwater system to respond to initiatingevents. The finding is greater than minor using Example 1.f of Inspection ManualChapter 0612, Appendix E. Similar to the example, the inspectors identified thatPacific Gas and Electric did not consider unavailability time for the Unit 1 auxiliaryfeedwater system, although the unavailability time was due to prior poormaintenance practices on Valve FW-1 -FCV-437. If the unavailability time wasconsidered, the 10 CFR 50.65(a)(2) evaluation would be invalid. Using theSignificance Determination Process Phase I worksheet in Inspection ManualChapter 0609, Appendix A, the finding is of very low safety significance, since therewas no loss of an actual safety function, no loss of a safety-related train for greaterthan the Technical Specification allowed outage time, and the finding is notpotentially risk significant due to a seismic, fire, flooding, or severe weatherinitiating event (Section 1 R12).

* Green. The inspectors identified a noncited violation of 10 CFR Part 50,Appendix B, Criterion l1l, when Pacific Gas and Electric personnel failed toadequately evaluate the capability of core exit thermocouples to measure the radialtemperature gradient for Quadrant 1 of the Unit 1 reactor core. Specifically,maintenance personnel inadvertently swapped core exit thermocouples at aconnection, leaving only three operable thermocouples per Trains A and B forQuadrant 1. When questioned by the inspectors, engineering personnel could notprovide an adequate technical bases for how measurement of radial temperaturegradient could be accomplished.

The finding impacts the mitigating system cornerstone through degraded overallavailability of the components within a system used to assess and respond toinitiating events to prevent undesirable consequences. The finding was greaterthan minor when compared to Example 3.a of Inspection Manual Chapter 0612,Appendix E. Similar to Example 3.a, Pacific Gas and Electric performed additionalwork to verify the ability of the core exit thermocouples to measure radialtemperature gradient within Quadrant 1 of the Unit 1 reactor core. Using theSignificance Determination Process Phase 1 screening worksheet from InspectionManual Chapter 0609, Appendix A, the finding was determined to be of very low

Enclosure

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safety significance, since the deficiency was confirmed not to result in loss offunction per Generic Letter 91-18, Revision 1 (Section 1 R1 9).

Green. A self-revealing violation of 10 CFR Part 50, Appendix B, Criterion XVI, wasidentified for failure to promptly identify and correct a condition adverse to quality.Specifically, in December 2000, Pacific Gas and Electric failed to identify andcorrect the population of Rockwell-Edwards valves in safety-related and risk-significant systems that were susceptible to failure of the packing gland followerflange from intergranular stress corrosion cracking. Pacific Gas and Electricreceived an industry notification in December 2000 that Rockwell-Edwards valveswere vulnerable for this type of failure, but initiated corrective actions on a verylimited population of valves (those involving a trip risk). As a result, on December3, 2003, the packing gland follower flange for safety injection Valve SI-1 -8890A(pressure equalization valve) on the hot leg injection line failed, due tointergranular stress corrosion cracking, resulting in excessive packing glandleakage.

The finding impacted the mitigating systems cornerstone through degradedequipment performance for a system train that responds to initiating events toprevent undesirable consequences. The finding is greater than minor because thefinding would become a more significant safety concern if the valve condition wasleft uncorrected. The amount of leakage from the valve would be significantlygreater than a 30 drop per minute leak rate, if the safety injection pumps were fullyrunning in the hot leg injection mode. The Valve Sl-1-8890A leak rate is boundedby a residual heat removal pump seal failure. Pacific Gas and Electric concludedthe safety injection system was operable but degraded because both safetyinjection system trains would be available to provide adequate flow if a demandoccurs. Using the Significance Determination Process Phase 1 worksheet inInspection Manual Chapter 0609, Appendix A, the finding was determined to be ofvery low safety significance, since there is no loss of an actual safety function, noloss of a safety-related train for greater than the Technical Specification allowedoutage time, and the finding is not potentially risk significant due to a seismic, fireflooding, or severe weather initiating event (Section 40S2.2)

Cornerstone: Occupational Radiation Safety

* Green. A finding was identified because Pacific Gas and Electric failed tomaintain collective doses as low as is reasonably achievable. Specifically, workactivities associated with Radiation Work Permit 03-2055, "Reactor Coolant Pump(RCP) 2-2, 10 year inspection," exceeded 5 person-rem and the dose estimation bymore than 50 percent due to a miscommunication among work groups.

The failure to maintain collective doses as low as is reasonably achievable is aperformance deficiency. This finding was more than minor because it is associatedwith the Occupational Radiation Safety Cornerstone attribute (program and

Enclosure

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process) and affected the associated cornerstone objective (to ensure adequateprotection of workers' health and safety from exposure to radiation). Thisoccurrence involved inadequate planning which resulted in unplanned, unintendedoccupational collective dose for the work activity. When processed through theOccupational Radiation Safety Significance Determination Process, this findingwas found to have no more than very low safety significance because the findingwas an as low as is reasonably achievable planning issue and Pacific Gas andElectric Company's 3-year rolling average collective dose was less than135 person-rem (Section 20S2).

B. Licensee-Identified Violations

None.

Enclosure

CONTENTS

PAGE

SUMMARY OF FINDINGS . ...................................................... 1

REACTOR SAFETY

1 R04 Equipment Alignments ............ .................................. 11 R05 Fire Protection . .................................................... 31 R06 Flood Protection ............ ..................................... 71 R11 Licensed Operator Regualification ..................................... 81R12 Maintenance Effectiveness ............... .......................... 81 R13 Maintenance Risk Assessments and Emergent Work Control ..... .......... 1 11R14 Operator Performance during Nonroutine Evolutions and Events, Including

Followup Response to Earthguakes Impacting Diablo Canyon Power Plant .... 121 R16 Operator Workarounds ............ ................................. 171 R19 Postmaintenance Testinq ........... ................................ 171 R22 Surveillance Testing ............. .................................. 201 R23 Temporary Plant Modifications ....................................... 211 EP2 Alert Notification System Testing ..................................... 211 EP3 Emergency Response Organization Augmentation Testing ..... ............ 221 EP4 Emergency Action Level and Emergency Plan Changes ..... .............. 221 EP5 Correction of Emergency Preparedness Weaknesses and Deficiencies .... ... 231 EP6 Emergency Preparedness Evaluation ................................. 24

RADIATION SAFETY

20S2 ALARA Planning and Controls ....................................... 24

OTHER ACTIVITIES

40A1 Performance Indicator Verification .................................... 2640A2 Identification and Resolution of Problems .............................. 2740A3 Event Followup . .................................................. 3040A4 Crosscutting Aspects of Findings .................................... 3140A5 Other ........................................................... 3140A6 Management Meetings ............ ................................. 32

ATTACHMENT: SUPPLEMENTAL INFORMATION

Key Points of Contact .................... ............................... A-1Items Opened, Closed, and Discussed ..................................... A-1List of Documents Reviewed ............ ................................. A-2List of Acronyms . ...................................................... A-5

Enclosure

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* Unit 1, maintenance outage windows for Component Cooling Water HeatExchanger 1-2, Atmospheric Dump Valve MS-1 -PCV-1 9, and PositiveDisplacement Pump 1-3 on September 30

* Unit 2, Eagle 21 Protection Set Rack 13 Nonvolatile Random Access Memoryreplacement and Atmospheric Dump Valve MS-2-PCV-20 calibration on October 23

* Units 1 and 2, 500 kV breaker replacement work on November 6

b. Findings

No findings of significance were identified.

.2 Emergent Work

a. Inspection Scope

The inspectors observed two emergent work activities to verify that actions were taken tominimize the probability of initiating events, maintain the functional capability of mitigatingsystems, and maintain barrier integrity. The scope of work activities reviewed includestroubleshooting, work planning, plant conditions and equipment alignment, tagging andclearances, and temporary modifications. The following activities were observed duringthis inspection period:

* Unit 2, Valve FCV-495 actuator replacement

* Unit 1, Valve SI-1-8890 packing leakage

b. Findings


1R14 Operator Performance during Nonroutine Evolutions and Events, Includinq Followup inResponse to Earthquakes Impacting Diablo Canyon Power Plant (71111.14)

a. Inspection Scope

The inspectors reviewed three inspection samples (two earthquakes and high PacificOcean swells) of nonroutine evolutions or events.

.1 Earthquakes In the Vicinity of the Diablo Canyon Power Plant

Background

Enclosure

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Diablo Canyon Power Plant is located in a seismically active area along the interface ofthe Pacific and North American Plates. Several faults are located within 50 miles of theplant. PG&E is required by the operating license to maintain a Long-Term SeismicProgram to reevaluate the seismic design bases against insights and knowledge gainedwith each seismic event. FSAR Update Section 3.7 describes the seismic design basis ofthe facility. The plant was designed for ground motion from a Design Earthquake,equivalent to an "Operating Basis Earthquake," in which the plant can be expected tocontinue to operate. This value is ground motion acceleration at the containment base of0.2g. The Double Design Earthquake, equivalent to a "Safe Shutdown Earthquake," is thedesign basis for most safety-related structures, and has ground motion acceleration of 0.4.The plant is also evaluated for the maximum ground acceleration which can result from anearthquake originating in the Hosgri fault. This evaluation ensures the plant can be safelyshut down if the expected maximum ground motion were to occur.

Technical Specification 3.3.1, "Reactor Trip System," requires instrumentation to initiate areactor trip for a nominal ground acceleration of 0.35 g. An earthquake force monitor,which has three sensors, provides an alarm in the control room at a minimum of 0.01 g ofground acceleration. Procedure CP M-4, "Earthquake," Revision 18, addresses theactions required to be taken in the event of an earthquake of 0.01 g or greater.

Deer Canyon Earthquakes

Description

At 12:52 a.m., on October 18, 2003, Diablo Canyon Power Plant Units 1 and 2 declared aNotification of Unusual Event (NOUE) because an earthquake that measured 3.4 was feltby the control room operators. No damage to plant equipment was observed and bothunits remained at 100 power throughout the event.

A preshock occurred at 12:27 a.m. that lasted approximately 3 seconds and was felt by thecontrol room operators. No alarms or other effects were noted. The primary shockoccurred at 12:39 a.m. and lasted approximately one second. The epicenter of the seismicevent was located 2.8 miles east-southeast of the plant (within the owner controlled area)and measured 3.4. The primary shock resulted in momentary turbine bearing highvibration alarms on both units and a high level alarm on the Unit 1 Safety InjectionAccumulator 1-3. The plant's seismic monitor recorded a peak acceleration of 0.02 g.

Following declaration of the NOUE, operators entered Procedure CP M-4, whichcontained instructions for response to earthquakes detected at the site. The shift managerinitiated a preliminary evacuation of the intake structure (where valve maintenance was inprogress) until the extent of the seismic event was understood. PG&E performedwalkdowns of both containments and all vital areas to ensure no immediate structuraldamage was evident. PG&E performed enhanced monitoring of safety-related tank levelsto ensure no ruptures occurred. No damage to any plant equipment was identified.

Enclosure

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Following confirmation that the earthquake resulted in no plant damage, PG&E exited theNOUE at 3:30 a.m. The inspectors responded to the site to monitor PG&E's actions andverified that PG&E performed the actions prescribed by Procedure CP M-4. Theinspectors walked down safety-related areas of the plant and noted no evidence ofdamage that would affect safety system operability. The inspectors continued to examinethe status of structures following the October 18, 2003, earthquake during routine plantstatus walkdowns throughout the inspection period.

The inspectors reviewed Special Report 50-275;323/03-03-00, "Seismic Event ofOctober 18, 2003," which discussed the Deer Canyon earthquakes of October 18 andprovided analysis of the effects of the earthquakes on plant structures, systems, andcomponents. The inspectors found the report properly analyzed the seismic data and theimpact that the ground motion had on structures, systems, and components.

San Simeon Earthquake 35 Miles Northwest of the Site

Description

At approximately 10:30 a.m. PST on December 22, 2003, the resident inspectors heard anoise on the roof of the Diablo Canyon administrative building. The inspectors respondedto the control room to report this information to the shift manager. The shift managerreceived similar reports from personnel in the warehouse and the training building outsidethe protected area. The inspectors and the operators verified that no alarms were receivedin the control room and that the seismic monitor did not register this event. The shiftmanager and the inspectors reviewed Procedure CP M-4 and verified that no action wasrequired.

At 11:16 a.m. PST a magnitude 6.5 earthquake struck 35 miles north-northwest of DiabloCanyon. Both resident inspectors were at the site. The shaking lasted 22 seconds. Thesenior resident inspector (SRI) immediately contacted the Region IV branch chief andinformed the branch chief that an earthquake had been felt.

While the SRI was briefing Region IV, the resident inspector (RI) responded to the controlroom at 11:18 a.m. to observe the operators. The RI walked down the panels, reviewedthe status of safety systems, and verified that PG&E was implementing the emergencyplan. The RI noted that the seismic monitor recorded a seismic event of 0.04g. The RIestablished the NRC's reactor safety counterpart link and advised the NRC headquartersoperations officer that PG&E would soon be declaring a NOUE.

The SRI reported to the control room to observe PG&E actions. The inspectors verifiedthat the requirements of Procedure CP M-4 were followed. The procedure requiredverification of the tank levels of all of the major safety-related tanks to ensure that nocatastrophic failures of the important tanks had occurred. The inspectors verified theapplicable tank levels. The procedure also required a complete walkdown of plant areas.PG&E received annunciators for the Unit 1 spent fuel pool level and safety injection

Enclosure

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accumulator high and low levels for both units during the seismic event because ofsloshing of the water. Operators received temporary alarms that included high vibrationfor the Unit 1 turbine. The operating electrohydraulic control pump tripped and wasimmediately restarted. Operators cleared the alarms following the shaking.

PG&E declared a NOUE at 11:22 a.m. The inspectors verified that PG&E made therequired calls to the state and local officials. PG&E sent personnel to the EmergencyOperating Facility (EOF), which is co-located with the San Luis Obispo County Office ofEmergency Services to assist in monitoring the community and the emergency servicesresponse. PG&E established a video conference between the EOF and the shiftmanager's office for the next 24 hours. One of the inspectors was present in the shiftmanager's office during each of the updates between the EOF and the control room. TheEOF advised the control room of damage to Highway 46 and fallen rocks on Highway 41,which is an emergency evacuation route. The inspectors communicated the status of localroadways to Region IV. Highways 46 and 41 had debris on the road, and Highway 46experienced some buckling, but the highways were passable for emergency responsepurposes. In addition, personnel in the EOF communicated the status of severalemergency sirens that were inoperable because of the power outages in San Luis Obispocounty.

Fifty-six of the 131 emergency sirens were inoperable because of power outages.Alternate means of notifying people within the affected areas were available. As of3:40 p.m., on December 22, 2003, 35 sirens were without power, and at 6 p.m. 26 sirenswere still without power. At 1:30 a.m., on December 23, 2003, four sirens were withoutpower. The remaining four were restored in the subsequent 24 hours.

The inspectors monitored reports of PG&E walkdowns of the plant. At approximately3 p.m., the Rls began independent inspections of plant equipment, for Phase I of the NRCinspection plan following the earthquake. One RI remained in the control room to monitoroperator actions and maintain communications within the agency, while the other inspectorwalked down plant areas.

The inspectors walked down the turbine building first. The emergency diesel generators,the component cooling water heat exchangers, and high voltage switchgear are in thisbuilding. The inspectors verified that no leaks existed in the safety-related systems andthat no cracks were evident in structural members.

The inspectors then walked down the switchgear areas of the auxiliary building. Theinspectors verified that no damage occurred in the ac and dc switchgear rooms, the cablespreading room, and the battery rooms.

The inspectors entered the radiologically controlled area of the auxiliary building andperformed complete inspections of the emergency core cooling pumps and systems,component cooling water pumps, auxiliary feedwater pumps, and RHR system heatexchangers.

Enclosure

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The inspectors entered the fuel building and verified the level in the spent fuel pools. Allstructural elements in the spent fuel pool were unaffected. Spent fuel pool water claritywas good. No cracks were evident in the fuel building ventilation system or structuralmembers.

The inspectors walked down the outside areas of the plant. The inspectors verified thatthe applicable security barriers were still intact. The inspectors verified that the majoroutside tanks (condensate storage tanks, refueling water storage tanks, primary waterstorage tanks, and fire water storage tank) had no cracks or obvious damage. Theinspectors toured the intake structure and verified that no damage occurred to thetraveling screens and auxiliary saltwater pumps, pipes, and valves.

The Rls provided continuous site coverage until PG&E exited the NOUE. Because thearea continued to experience aftershocks, PG&E elected to remain in a NOUE forapproximately 24 hours. The Rls continued to inspect the facility and monitor control roomactions for the duration of the NOUE. During the evening, the inspectors walked down theoffsite power sources (startup transformers) and continued to monitor communications withthe emergency facilities. The inspectors examined the auxiliary and startup transformersfor damage. PG&E personnel reported that two switches were damaged in the 230 kVsystem at the offsite Morro Bay switchyard. The Morro Bay switchyard is one source ofoffsite power to the startup transformers. PG&E declared the startup transformersinoperable to provide safe electrical isolation and cleared the 230 kV lines to supportreplacement of the damaged switches. The startup transformers were returned tooperable status within the 72-hour limiting condition for operation action statement. TheRis remained at the site, continuing to inspect and monitor PG&E actions until 2 p.m. PSTon December 23. PG&E exited the NOUE at approximately 12:15 p.m., PST on December23, 2003.

In the days following the event, the inspectors continued to review PG&E's response toaftershocks and the adequacy of the PG&E procedures and the Emergency Plan. Theinspectors attended PG&E's Event Review Team meetings throughout the remainder ofthe inspection period.

a. Findings

During the inspections, no system or structural damage or evidence of differentialdeflections were detected, and no site ground effects were noted during exterior visualinspections. In addition, no damage was noted to the administration building, which isdesigned to the Uniform Building Code. The licensee's immediate response to theearthquake was effective in ensuring continued safe operation, and their implementation ofthe NRC's prompt notification requirements was timely and correct.

All seismic instrumentation functioned correctly. The NRC inspectors conducted a reviewof the required surveillances on seismic monitoring instruments. All instruments werecorrectly calibrated. The inspectors noted that the licensee is in the process of upgrading

Enclosure

-17-

the current Earthquake Force Monitor to a digital distributed system that will provide betterinformation (e.g., wider frequency response and more monitoring locations).

Casualty Procedure M-4 was used in responding to the earthquake. Although overallresponse to the earthquake was adequate, several lessons were learned by PG&E from asubsequent review of the implementation of the procedure. PG&E has begun a generalrevision to improve its quality based on this experience.

The inspectors reviewed PG&E's reportability procedure for loss of the early warningsystem sirens. During the review, the inspectors noted that the procedure for notificationof the NRC for a loss of the early warning system sirens only addressed sirens within a1 0-mile radius and not the entire Diablo Canyon Emergency Planning Zone, as defined inthe Emergency Plan. In this case, the licensee did inform the NRC of the loss at the timethe Unusual Event notification was made.

.2 Units 1 and 2 Downpowers because of High Pacific Ocean Swells

a. Inspection Scope

On December 9, 2003, PG&E received warning of impending high Pacific Ocean swells.Upon notification of the high swells, PG&E management determined that the units wouldbe ramped down to approximately 25 percent power to prevent the traveling screens,from being clogged with kelp, which could necessitate tripping the circulating water pumpsand a reactor trip of the affected unit. At 1:30 a.m., on December 10, operators slowlydecreased power on both units. The inspectors responded to the site and monitored theoperator performance during the downpower and operator response to any highdifferential pressure across the traveling screens.

b. Findings


1R16 Operator Workarounds

a. Inspection Scope (71111.16)

The inspectors reviewed three samples of operator workarounds.

The inspectors reviewed PG&E's documented actions in which degraded conditions orchanges to accident analyses required additional operator action beyond that credited inthe design basis to compensate for these conditions. PG&E tracked two types of theseconditions: operator burdens and operator workarounds.

PG&E defined an operator burden as a manual action taken to compensate for degradedequipment that affected normal operation of a unit. PG&E had 17 operator burdens.

Enclosure

ucf z Enclosure 40 iUNITED STATES

NUCLEAR REGULATORY COMMISSIONREGION IV

611 RYAN PLAZA DRIVE, SUITE 400X ARLINGTON, TEXAS 76011-4005

January 16, 2004

Gregory M. Rueger, Senior VicePresident, Generation andChief Nuclear Officer

Pacific Gas and Electric CompanyDiablo Canyon Power PlantP.O. Box 3Avila Beach, CA 93424

SUBJECT: DIABLO CANYON POWER PLANT - PRELIMINARY RESULT OF NRC EVENTFOLLOWUP FOR THE DECEMBER 22, 2003, SAN SIMEON EARTHQUAKE

Dear Mr. Rueger:

During the period of December 22, 2003, through January 9, 2004, the NRC has beenconducting event followup inspections at the Diablo Canyon Nuclear Plant in direct response tothe December 22, 2003, San Simeon earthquake. The purpose of this letter is to communicateto you the preliminary results of these inspection activities and to describe the NRC's plannedand future actions with respect to further followup, actions, and documentation associated withthe earthquake and the assessment of its impact on the Diablo Canyon plant.

The inspections to date were conducted under Inspection Procedure 71153, "Event Follow-up,"and the enclosure to this letter provides a summary of the inspection scope and preliminaryinspection results in the areas reviewed. Please note that the final inspection results andfindings are not being issued at this time, are subject to further review, and will be documentedin NRC Inspection Reports 05000275;323/2003008 and 05000275;323/2004002 to be issuedapproximately at the end of January and April 2004, respectively.

In summary, the NRC actions in response to the earthquake focused on the following areas:

* The impact of the seismic event on the integrity of structures, systems, components,and containment barriers that are important to the safe operation of the nuclear plant;

* The adequacy of the licensee's response to the event; and

* Whether the event was within the design basis for the nuclear plant.

The: NRC's overall response to the San Simeon earthquake consists of three phases whichinvolve the site resident inspectors and Regional and Office of Nuclear ReactorRegulation (NRR) representatives. The NRR representatives were seismic experts thatprovided technical experience to the inspection activities. The first phase, which has beencompleted, involved the immediate response to the December 22, 2003, earthquake by NRCinspectors. Immediately following the earthquake, both resident inspectors, who were onsite at

11-1 --- I--.


the time of the earthquake, reported to the control room and walked down control board panelsto ascertain the status of safety systems and verify that your staff had implemented theiremergency plan. The inspectors also performed independent visual examinations of selectedstructures, systems, and components. During these walkdowns, the inspectors did not identifyany broken, shifted, or leaking pipes; damaged support braces; displaced equipment; or cracksor spalling in concrete walls and floor or the plant's foundation that would indicate any signs ofdamage.

Phase 2 of the NRC's followup involved an onsite inspection during the week of January 5-9,2004. The inspection focused on detecting evidence of movement resulting from seismicacceleration, and visual examination of accessible portions of selected structures, systems,subsystems, and components to determine whether the seismic event resulted in degradation.

(The structures, systems, subsystems, and components selected for examination wereprioritized based on their risk significance. During this Phase 2 portion of the inspection, theNRC staff concluded that, in order to assure that there was no damage to equipment inside thecontainment buildings, it would be necessary to perform a visual examination of selectedstructures, systems, subsystems, and components inside one of the containment buildings.Accordingly, an inspection was made of the Unit 2 containment's structures, systems,subsystems, and components. No system or structural damage or evidence of differentialdeflections were detected. The NR5C staff concluded that, based on there being no damageand the near identical designs of both units' containment buildings, an inspection of the Unit 1containment building could be deferred until the Unit 1 refueling outage scheduled to begin inMarch 2004.

Phase 3 of the NRC's actions are ongoing. Specifically, additional inspections are planned,particularly including the visual inspections in Unit 1 containment during the March 2004refueling outage and further review of your Special Report, submitted to the NRC on January 5,2004, as we understand you intend to supplement that report.

in addition, the NRC plans to conduct a Category 1 technical meeting with you regarding yourJanuary 5, 2004, Special Report in San Luis Obispo, California. This meeting will be open topublic observation and will provide attending members of the public a period for comments andquestions prior to the conclusion of the meeting. Immediately following the technical meetingorn the Special Report, a second" Category 1 public m eetingg will be conducted to. provided yourstaff a more detailed interim exit for the Phase 1 and~d 2 inspection activities and a review ofongoing and planned inspection activities.

in- accordance with 10 CFR 2.790 oft The NRC's "Rules of Practice," a copy of thi letter and itsEnclosure wil~l be available electronically for public inspection in the N-RC Public Document


Room or from the Publicly Available Records (PARS) component of NRC's documentsystem (ADAMS). ADAMS is accessible from the NRC Web site at http://www.nrc.gov/reading-rm/adams.html (the Public Electronic Reading Room).

Sincerely,

IRAI


Dockets: 50-27550-323

Licenses: DPR-80DPR-82

Enclosure:Diablo Canyon Response to San Simeon

Earthquake on December 22, 2003

cc w/enclosure:David H. Oatley, Vice President

and General ManagerDiablo Canyon Power PlantP.O. Box 56Avila Beach, CA 93424

Lawrence F. Womack, Vice President, PowerGeneration & Nuclear Services


James R. Becker, Vice PresidentDiablo Canyon Operations andStation Director, Pacific Gas andElectric Company

Diablo Canyon Power PlantP.O. Box 3Aviila Beach, CA 93424

Sierra Club California2650 Maple AvenueMorro Bay, CA 93442

Pacific Gas and Electric Company -4 -

Nancy CulverSan Luis Obispo Mothers for PeaceP.O. Box 164Pismo Beach, CA 93448

ChairmanSan Luis Obispo County Board ofSupervisors

Room 370County Government CenterSan Luis Obispo, CA 93408

Truman Burns\Robert KinosianCalifornia Public Utilities Commission505 Vani Ness Ave., Rm. 4102San Francisco, CA 94102-3298

Diablo Canyon Independent Safety CommitteeRobert R. Wellington, Esq.Legal Counsel857 Cass Street, Suite DMonterey, CA 93940

Ed Bailey, Radiation Control Program DirectorRadiologic Health BranchState Department of Health ServicesP.O. Box 942732 (MS 178)Sacramento, CA 94234-7320

Richard F. Locke, Esq.Pacific Gas and Electric CompanyP.O. Box 7442San Francisco, CA 94120

City EditorThe Tribune3825 South Higuera StreetP.O. Box 112Sang Luis Obispo, CA 93406-01'12

Ja:mes D. Boyd, CommissionefrCalifornia Energy Commission.1516. Ninth Street (MS 34)Sacramento, CA 95814


Chief, Technological Services BranchFEMA Region IX1111 Broadway, Suite 1200Oakland, CA 94607-4052

Enclosure

Preliminary NRC Inspection Results to Date for Diablo CanyonResponse to San Simeon Earthquake on December 22, 2003

A. Background Information:

On December 22, 2003, at 11:16 a.m. PST, with both units operating at 100 percent power, a6.5 magnitude earthquake occurred 50 km NNW of Diablo Canyon Power Plant at a depth ofabout 7 kilometers near San Simeon, California. The earthquake was measured as 0.04gacceleration at the top of the containment base. At 11:22 a.m. PST, the licensee declared an"Unusual Event" based on exceeding 0.01g acceleration.

The Operating Basis Earthquake and the Design Basis Earthquake maximum groundaccelerations for Diablo Canyon are 0.2g and 0.4g, respectively. The reactor trip system has areactor trip setpoint nominal value of 0.35g acceleration. The reactor trip was set at 0.3g at thetime of the San Simeon earthquake. Therefore, the measured acceleration was less than15 percent of the reactor trip setpoint and well within the bounds of the seismic analyses. Thestation is also evaluated for its capacity to withstand ground acceleration resulting from a7.5 magnitude earthquake originating in the offshore Hosgri fault.

Units 1 and 2 remained at full power throughout the event. Both NRC resident inspectors wereonsite at the time of the earthquake, responded to the control room to observe immediateoperator actions, and maintained an NRC presence onsite for the next 24 hours. Immediatelyfollowing the first shock, the resident inspectors established a direct open telephone linkbetween the station's control room and both the NRC headquarters office in Rockville,Maryland, and the NRC Region IV office in Arlington, Texas. This line was kept open by one ofthe two inspectors and information concerning the station's status was continuously provided toNRC staff.

Fifty-six of 131 early warning system sirens lost power as a result of the earthquake. Alternatemeans of notifying people within the affected areas were available. The evacuation routesremained accessible. As of 3:40 p.m., on December 22, 2003, 35 sirens were without power,and at 6 p.m. 26 sirens were still without power. At 1:30 a.m., on December 23, 2003, 4 sirenswere without power. These remaining 4 were restored in the subsequent 24 hours.

B. Inspection of Structures, Systems, and Components

Purpose:

To identify any structural damage to plant equipment and structures that might negativelyimpact safe operation.

Preliminary Inspection Results to Date:

As part of the NRC's immediate response, the onsite resident inspectors performed visualinspections in the control room and other safety-related areas of the plant, such as the auxiliarybuilding, saltwater intake structure, and fuel handling buildings. No evidence of damage that

-2-

would affect safety system operability was identified. The inspectors also observed selectedlicensee visual examinations of plant structures, systems, subsystems, and components andconcluded that licensee was performing adequate examinations.

During the period of January 5-9, 2004, further inspections were performed by the residentinspectors and an NRC senior reactor inspector. During this inspection activity, all levels of theturbine, auxiliary, fuel handling, saltwater intake, and containment buildings were visuallyinspected, with particular attention given to systems and components having the most risksignificance. During the inspections, no system or structural damage or evidence of differentialdeflections were detected, and no site ground effects were noted during exterior visualinspections. In addition, no damage was noted to the administration building, which is designedto Uniform Building Code.

C. Inspection of Licensee Event Response

Purpose:

To assess the adequacy of the licensee's response to the earthquake.


The licensee's immediate response to the earthquake was effective in ensuring continued safeoperation. The licensee's subsequent inspections were effective in evaluating whether anystructural damage occurred.

The licensee convened an Event Response Team to capture lessons learned and to fullyunderstand the response of the plant systems. The NRC inspectors reviewed the team'sfindings and concluded that the scope and depth of the team's reviews were comprehensiveand; effective. The review of control room annunciator alarms identified enhancements neededto assist control room operators and to preclude unnecessary actions in a future event.

The licensee's implementation of N;RC's prompt notification requirements was timely andcorrect.

All seismic instrumentation functioned correctly. The NRC inspectors conducted a review of therequired surveillances on seismic monitoring instruments. AM ifnstruments were correctlycalibrated. The inspectors noted that the licensee is in the process of upgrading the currentEarthquake Force Monitor to a digital distributed system that will provide better information(e.g., wider frequency response and more monitoring locations).D. Inspection of the Licensee's Earthquake Response Procdu-re and Dd~tiuentation

g - Revi~ewM. ["n pe-n of th ic e ,,n

Purpose:

To assess the adequacy of the licensee's procedures and documentation relative to theearthquake.

-3-


Casualty Procedure M-4 was used in responding to the earthquake. Although overall responseto the earthquake was adequate, several lessons were learned by the licensee from asubsequent review of the implementation of the procedure. The licensee has begun a generalrevision to improve its quality based on this experience. The NRC plans to review thisprocedure following its revision.

The inspectors also performed a review of the licensee's Special Report 03-04, datedJanuary 5, 2004. This Special Report is required by the facility operating license (i.e., thelicense requires the licensee to evaluate each seismic event where onsite monitoringinstruments are actuated to determine the magnitude of the ground motion and resultant effectupon facility features important to safety). The inspectors noted that this report was preparedbased solely on the seismic monitoring instrument located on top of the containment basematwithout consideration of other seismic monitoring instruments at the station. As a result of thisobservation, the licensee issued a corrective action document to submit a supplemental reportto the NRC that will describe the analysis of data from all actuated seismic monitoringinstruments (acceleration, displacement, and frequency spectrum) and will compare these todesign values at the corresponding location in the plant. The NRC will review this supplementalreport upon receipt from the licensee.

The inspectors reviewed the licensee's reportability procedure for loss of the early warningsystem sirens. During the review, the inspectors noted that the procedure for notification of theNRC for a loss of the early warning system sirens only addressed sirens within a 10-mile radiusand not the entire Diablo Canyon Emergency Planning Zone, as defined in the EmergencyPlan. In this case, the licensee did inform the NRC of the loss at the time the Unusual Eventnotification was made. The licensee issued a corrective action document to further evaluatethis observation.

Lnclosure 5

December 22,2003 San Simeon Earthquake

PRELIMINARY REPORT ON DECEMBER 22, 2003 SAN SIMEON EARTHQUAKE

ByRakesh K. Goel, M.EERI

Department of Civil & Environmental Engineering,California Polytechnic State University, San Luis Obispo, CA 93407

rgoel(gcalpoly.edu

A strong earthquake of magnitude 6.5 (Mw) struck the Central Coast of California at11:15:56 AM PST (19:15:56 UTC) on Monday, December 22, 2003. The epicenter (Figure 1)was 11 km (7 mile) NE of San Simeon, at a depth of about 8 km (5 mile). Two people werekilled and about 40 buildings collapsed or severely damaged at Paso Robles which is locatedabout 39 km (24 mile) from the epicenter. At least 40 people were reported to be injured in thePaso Robles-Templeton area. This preliminary report presents basic information on the epicenterlocation, intensity of shaking, and performance of buildings in the Central Coast region of theCalifornia.

Epicenter Location and Shaking Intensity

The Central Coast of California has several active faults (Figure 2). Although exactlocation of the earthquake of December 22, 2003 is still being determined, this earthquakeoccurred somewhere on the northern end of the San Simeon/Oceanic/HosGri Fault System. Earlyanalysis by USGS and UC Berkeley indicates that it had a thrust (reverse faulting) mechanism;reverse faulting occurs when compression stresses push the fault block up the fault line "reverse"to the gravity (Figure 3). The last major earthquake in this area was the Bryson earthquake in1952 with a magnitude of 6.2.

34o1~4122 , 121E0 129

Figure 2. Faults in Central Coast of California(Adapted from a USGS map).

Figure 1. Location of the December 22, 2003 SanSimeon earthquake (USGS).

(ioei Preliminary ReportGoel I Preliminary Report

December 22, 2003 San Simeon Earthquake

PasoRobles I.

tA-aademin

.on Bay

San Luis Obispo

an Luis 0bispo 6

Figure 3. Reverse fault mechanism'. Figure 4. Map of San Luis Obispo County2 .

Figure 5 shows the shaking intensity map of the San Simeon earthquake. The intensitywas about VII in Atascadero, Cambria, Cayucos, Los Osos, Morro Bay, Nipomo, Oceano, PasoRobles, San Miguel, San Simeon, Shandon and Templeton (see map of the San Luis ObispoCounty in Figure 4 for locations of various cities). Further south, the intensity reduced to VI inArroyo Grande, Grover Beach, Guadalupe, Pismo Beach, San Luis Obispo, Santa Margarita andSanta Maria.

CISN Rapid Instrumerital Intensity Map Epicenter: 11 km NE d San Simeon. CAMo-DN.22.200311:1"s6AMPST MA6. N03.71 W121.0 Depth:76ka IQ.40148755

CISN Peak Accal. Map (in %g) Epicenter: 1i kn NE of San Simeon CAM-O.o22.200311:10.56A0PST MISS N35.71 W121.0 D.PtIh 7634 I040148755

.122 s >a |12 -1201

*1 22' 2'A0*03partaln ..55 U.,r-# asa 144 192t@ 9259 193 3405Z 6412 .54410t4004..4 .0.1 011.l1 1144 344 i14 [-S 3 164 645 .159

IOS. IL' i a V

Figure 5. Intensity map (CISN). Figure 6. Peak ground acceleration map (CISN).

The largest shaking observed was at a CGS-instrumented 1-story hospital in Templeton,about 38 km (24 mile) from the epicenter (though much closer to the projected southern end ofthe rupture). The hospital recorded about 50%g horizontal motion and 30%g vertical motion atthe ground level3. Templeton is about 10 km (6 mile) south of Paso Robles, where significantdamage occurred during the earthquake (see Figure 4 for city locations). Therefore, it is likely

atAdapted from httn:/Iwww3 ulakron. edu/seotzraphv/Irb/phvsf97/Iectures/platetect/sIdO3 htrn2 Adapted from http://www.slocoupons.com/maes I .htm

Second Internet Quick Report: CISN Strong-Motion Data from the M6.5 San Simeon Earthquake of December 22,2003

Goel 2 Primvnuaiiia 1\PUI L-FrL VH1lll )ir DeUport


that Paso Robles experienced horizontal accelerations in excess of 50%g. The station closest tothe epicenter was near Cambria, 12 km (8 mile) from the epicenter, near a Caltrans bridge onHwy 1. Though the station is much closer, it only recorded 18%g. This early data indicatesapparent strong directivity in the direction of the rupture propagation toward Templeton. Anotherrecord was recovered from the San Luis Obispo, about 61 km (38 mile) to the south of theepicenter, where 17%g was recorded at a USGS station downtown. A contour map of the peakhorizontal ground accelerations during the earthquake is shown in Figure 6.

Performance of Buildings in Paso Robles

Downtown Paso Robles, located about 39 km (24 miles) from the epicenter, suffered themost damage during the San Simeon earthquake. The damage was concentrated in the three-block area of the historic downtown district of the city (see sketch in Figure 7). Summarizedfirst is the overall observations on the damage pattern in the downtown area followed by moredetailed description for selected buildings.

M -

A aN

13t Street C W120.68805

12thSre N35.ff2675 1NS5.92613(I) W120.63931 W120.68775

Cy r N35.62642. W120.68t98N35.62553, W120.69030 i City Park C-egi. Librry

Pas Robles Inn

N35.62471. W120.69011Paso Robles City Hall

Paso Robles Downtown: Damaged Area LayoutBlocks with Major Damage are Shaded

(Sketch by Rakesh K. Goal, Not to Scale)

Figure 7. Damaged area in downtown Paso Robles.

Overall Damage Pattern

The largest damage was observed to buildings on both sides of the Park Street between12th and 13th Streets, and on 12th Street between Park and Vine Streets (see Figure 7 forlocations). The Acorn building, located on the corner of 12th and Park Streets, collapsed killingtwo people. Although the building housing Marlow Interior located on the corner of 12th andPark Streets but opposite to the Acorn building did not collapse, it suffered extensive structuraland nonstructural damage. Most other buildings on these streets suffered minor to majorstructural and extensive nonstructural damage. At the time of this report, access to thesebuildings had been restricted to building officials for evaluation purposes.

uoei �1 Preliminary ReporttGoel J Preliminary Report


Most buildings in the downtown Paso Robles business district area are very old, somemore than a century ago, constructed of unreinforced masonry. Unreinforced masonryconstruction is known to be especially vulnerable to earthquakes and it is not surprising that suchbuildings suffered extensive damage during the San Simeon earthquake. Most of these buildingswere not designed for seismic loads and lacked proper seismic detailing. A few had beenupgraded by tying the floor diaphragm to the walls. The damage level was much higher inbuildings that were not retrofitted compared to those that had been retrofitted. None of thebuildings with some kind of seismic retrofit scheme implemented collapsed indicating that evenbasic seismic retrofit can prevent collapse and resulting loss of life.

In general, buildings on the street corners performed poorly. For example, Acorn,Marlow Interior, Bistro Laurent, Cingular Wireless, and Ali's buildings that suffered the largestdamage were all located on street corners (see Figure 7). Configuration of these corner buildingswith windows on the street sides and solid opening-less walls on the two other sides createdextreme plan asymmetry, i.e., large eccentricity between floor center of mass and center ofrigidity. The resulting torsional motions during the earthquake shaking imposed much largerdemands on these buildings, compared to buildings with symmetric plans, leading to much largerdamage.

Unreinforced masonry buildings even without seismic retrofit located mid-block did notsuffer catastrophic failure that occurred in the Acorn building. Most buildings in the affectedarea, especially on the Park and 12th Streets, are constructed without any gap between them. Itseems that the adjacent buildings provided confinement to each other, except to those on thecorner, and prevented collapse.

Finally, the damage pattern indicates a much stronger shaking in the east-west direction,the direction normal to the fault rupture, compared to the north-south direction. This observationis consistent with the observation in the previous earthquakes that the shaking may be strong inthe fault-normal direction compared to the fault-parallel direction.

Acorn Building

The Acorn building is one of the oldest buildings in the downtown district of PasoRobles. A two story unreinforced masonry building constructed more than a century ago, ithoused a Clock Tower on the corner of 12th and Park Streets and several small businesses on theground floor on 12th Street and Park Street sides. This building collapsed resulting in the onlytwo fatalities during the San Simeon earthquake (Figure 8).

The lateral load carrying system of this two-story building appears to be unreinforcedmasonry walls, which support the timber floor and roof with additional metal sheet on the roof.Both the floor and the roof appear not to be properly tied to the walls. During the earthquake, theclock tower on the Park and 12th street corner of this building collapsed. Furthermore, the secondstory wall on the Park Street side appeared to have collapsed out-of-plane. As a result, the roofslid to the Park street side leaving a big gap in what appears to be collapsed roof of the secondhalf of the building on the 12th Street side.

The major shear resistance of this building appears to be in the north-south direction,with much smaller shear capacity in the east-west direction. As noted previously, the strongshaking was in the east-west direction. The wall on the west side (on the Park Street side) of thebuilding collapsed out-of-plane due to much smaller resistance.

Goel 4 r-AI--. DANA_+rreCl11m1mary report


I . ~..:

Figure 8. Collapsed Acorn building on the corner of 12th and Park Streets in downtown Paso Robles (Pictureby Rakesh Goel).

Marlow Interior Building

Located on the corner of 12th and Park Streets, the south and east elevations of this two-story building - the two sides facing the streets - have large window openings in the first storyand some windows in the second story (Figure 9). The other two sides, which face away from thestreets, have only a few window openings in the second story and solid wall in the first storywithout openings. This configuration led to significant eccentricity between the center of massand center of rigidity. The damage pattern described next for this building is consistent with thatexpected due to torsion.

This building suffered major structural damage and was red-tagged after the earthquake.Large cracks appeared on the south-east corner - the corner farthest away from the center ofrigidity - of the building (Figure 10). Apparently, this corner experienced large drifts due totorsion of the building during the earthquake. Significant diagonal shear cracks appeared in thefirst story wall on the east as well as the south sides; both these sides of the building face thestreets (Figure 11). This appears to be consistent with the expected large drifts in this wall of thefirst story. Much less cracking is visible in the second story wall (Figure 12). Drifts are expectedto be much smaller in this wall of the second story because of much fewer openings compared tothe first story. No cracks were visible in the north and west walls of the building.Ali's Persian Rugs Building

This two story building located on the south-west corner of Park and 1 3th Streets sufferedextensive loss of its cladding. The brick facade peeled off from near the roof level from faces onboth the Park and 13th Street. It appears that the brick facade was attached to the wall withcement mortar. No ties were noticeable on the open face of the building or the rubble below. Theother external structural damage appears to be minimal in this building.

NI P i r eGoel Preliminary Report


Figure 9. Marlow Interior building located at the Figure 10. Large cracks at the corner of the Marlowcorner of 12th and Park Streets in downtown Paso Interior building (Picture by Sam Vigil).Robles (Picture by Josh Marrow).

Figure 11. Crack pattern in the first story of the Figure 12. Crack pattern in the second story of theMarlow Interior building on the Park Street face Marlow Interior building on the Park Street face(Picture by Sam Vigil). (Picture by Sam Vigil).

Bistro Laurent Building

Located on the corner of Pine and 12t Streets, this one-story masonry building sufferedminor structural damage (Figure 14). A few bricks separated and fell from the decorativeparapet. This masonry building appears to have been retrofitted by tying the roof to the walls.The anchor bolts are clearly visible along the roof-line of this building. Clearly, this basic retrofitscheme appears to have prevented major damage to this building.

Lxoel Preliminary Report(Joel 6 Preliminary Report


Figure 13. Peeling of the brick facade in the second Figure 14. Minor peeling of bricks from thestory of the Ali's Persian Rug building on the corner decorative parapet of the Bistro Laurent building onof Park and 13th Streets in downtown Paso Robles the corner of Pine and 12th Streets in downtown Paso(Picture by Sam Vigil). Robles (Picture by Rakesh Goel).

Figure 15. Damage to the Cingular Wirelessbuilding on the corner of Pine and 13thStreets in downtown Paso Robles (Picture bySam Vigil).

Cingular Wireless Building

Figure 16. A close-up view of the seismic retrofit anchors inthe Cingular Wireless building (Picture by Rakesh Goel).

Located on the corner of Pine and 13th Streets, this one-story masonry building sufferedminor structural damage (Figure 15). The brick fagade on the south-west corner of the buildingseparated and fell. This masonry building also appears to have been retrofitted by tying the roofto the walls. The anchor bolts are clearly visible along the roof-line of this building (Figure 16).As noted previously for the Bistro Laurent building, this basic retrofit scheme appears to haveprevented major damage to this building.

(Joel 7 Preliminary ReportCGoel 7 Preliminary Report


Paso Robles Inn

Paso Robles Inn is located a short distance south-east of the historic downtown district.This Inn consists of a main restaurant with a three-story tall observation tower and several two-story buildings that house the guest quarters. The observation tower consists of a framesupporting the brick facade. Very little damage was noticeable in the observation tower (Figure17). The attached restaurant suffered moderate nonstructural damage: a few clay roof tiles cameloose and a glass broke in a few windows in the first and second stories (Figure 18).

Figure 17. Observation tower of the Paso Robles Inn Figure 18. Loss of windows and roof tile in restauranton Spring Street in Paso Robles (Picture by Rakesh of the Paso Robles Inn (Picture by Rakesh Goel).Goel).

Ps igure 1. Inwo-story guest quarter DiPaso Robles Inn (Picture by Sam Vigil).

Figure 20. Cracks in the brick walls of the guestquarter building at the Paso Robles Inn (Picture byRakesh Goel).

The two-story brick building housing the guest quarters in the front of the Paso RoblesInn (Figure 19) suffered significant cracking in the masonry walls (Figure 20). This portion ofthe Inn was closed. Other parts of the Inn were open for business as the damage was minor andmostly non-structural in nature.

Goel 8 Preliminary ReportGoel 8 Preliminary Report


Performance of Atascadero City Hall

Built in 1918, the Atascadero City Hall (Figure 21) is located about 63 km (39 mile) fromthe epicenter. Discussion with the city engineer indicated that the structure consists of reinforcedconcrete space frame with brick fagade. The exterior damage primarily consisted of cracks andsevere spalling of the brick fagade on the rotunda (Figure 22). Falling bricks from the fagadetook out a sky-light and fell on the tables of a room located at the rotunda office level. No onewas injured because this room was unoccupied at the time of the earthquake. The reinforcedconcrete space frame supporting the dome roof was found to have suffered no damage.

Figure Li. Atascadero CAty Hall (Picture by KakeshGoel).

Figure 22. Feeling of brick facade from the rotundaof the Atascadero City Hall (Picture by Rakesh Goel).

Internal damage consists of severe cracks in the walls and plaster throughout the building(Figure 23). The damage was more severe in the first story. Rotunda office where the citycouncil meets experienced spalling of plaster from the roof and the ring beam (Figure 24).Closets in the kitchen outside the city council chambers at the rotunda level opened and spilledtheir contents during the earthquake (Figure 25). Contents of the display cases in the lobby weretossed around during the earthquake. Several glass display pieces fell to the ground and broke(Figure 26).

Figure 21. Atascadero City HallGoel).

rigure LL. reeling o1 brick fapade from the rotundaof the Atascadero City Hall (Picture by Rakesh Goel).

(ioel9 Prlimiary eporUoel 9 Preliminary Report


figure 23. Iypical cracks in the walls of AtascaderoCity Hall (Picture by Rakesh Goel).

s ~s;^. r,- Wl-l Xrotunda of theRakesh Goel).

ig of plaster from ring beam of theAtascadero City Hall (Picture by

Figure 25. Damage in the kitchen of Atascadero City Figure 24. Damage in the lobby of the AtascaderoHall (Picture by Rakesh Goel). City Hall (Picture by Sam Vigil).

Performance of Buildings in Downtown San Luis Obispo

Although downtown San Luis Obispo has a large stock of unreinforced masonrybuildings, very little structural damage was observed in the city. The lack of damage in San LuisObispo may be attributed to relatively large distance from the epicenter - the city is about 61 km(39 mile) from the epicenter of the San Simeon earthquake - and low levels of groundaccelerations in the city - the peak horizontal ground acceleration recorded during theearthquake was about 17%g at a USGS recording station.

Ah Louis Store (Figure 25), a two-story unreinforced masonry building located on thecorner of Palm and Chorro Streets, is designated as a historic landmark in the city. No noticeablechange in cracks on the south-west wall, which has been retrofitted, was observed after theearthquake (Figure 26). However, new cracks appeared on the north-east wall of the building

(ioel 10 Preliminary ReportGJoel 10 Preliminary Report


(Figure 27). The building was temporarily closed for inspection and subsequently cleared foroccupancy.

Several vulnerable buildings in San Luis Obispo are located on the campus of theMission San Luis Obispo de Tolosa. This adobe structure survived the earthquake withoutdamage. The only noticeable damage was widening of existing hair-line cracks at the junction ofthe Bell-Tower building and the adjacent building (Figure 28). The mission was open forbusiness in the afternoon of December 22, 2003.

Figure 25. Ah Louis Store in downtownObispo (Picture by Rakesh Goel).

r igure Ao. CracKs existing prior to the eartnquaKe anuattempt to retrofit on the south-west wall of the AhLouis Store building (Picture by Rakesh Goel).

Figure 27. New cracks on north-east wall of the Ah Figure 28. Widening of cracks at junction of the bellLouis Store building (Picture by Rakesh Goel). tower and adjacent building in the Mission San Luis

Obispo de Tolosa in downtown San Luis Obispo(Picture by Rakesh Goel).

The campus of California Polytechnic State University houses numerous buildings ofvarious ages and types of construction. There was no reported structural damage on this campus.The only significant nonstructural damage was to a light fixture in the Recreational building; oneof the vertical rod supporting the light fixture pulled out from the roof due to insufficient threadlength (Figure 29).

Goel 11 Preliminary ReportGoel 11I Preliminary Report


Figure 29. Damage to a light fixture in Recreational building on the Campus of California Polytechnic StateUniversity, San Luis Obispo (Picture by Rakesh Goel).

Goel 12 Preliminary ReportGoel 12 Preliminary Report

Sent By: United States Nuclear Regulator; 805 595 2355; Dec-29-03 7:06PM; Page 2

Enclosure U

October 31, 2003

PG&E Letter No. DCL-03-141

U.S. Nuclear Regulatory CommissionATTN: Document Control DeskWashington, DC 20555-0001

Docket No. 50-275, OL-DPR-80Docket No. 50-323, OL-DPR-82Diablo Canyon Units 1 and 2Special Report 03-03: Seismic Event of October 18. 2003

Dear Commissioners and Staff:

On October 18, 2003, at 0039 PDT, with Unit I and Unit 2 operating at 100 percentpower, ground motion was felt and recognized as an earthquake by a consensus ofcontrol room operators. The earthquake force monitor recorded greater than 0.01 gfor the seismic event. Therefore, operations personnel declared an Unusual Event,in accordance with emergency action level (EAL) NUEI8. (Reference NRC EventNotification Number 40258.) At 0330 PDT, the Unusual Event was terminated uponconfirmation that no damage to the plant occurred.

This special report is submitted pursuant to Equipment Control Guideline (ECG)51.1, "Seismic Instrumentation." This ECG requires the following actions for aseismic event: For seismic monitoring instruments actuated dunng a seismic event,"data shall be retrieved from actuated instruments and analyzed to determine themagnitude of the vibratory ground motion. A special report shall be prepared andsubmitted to the Commission ... describing the magnitude, frequency spectrum, andresultant effect upon facility fbatures important to safety."

Enclosure I describes the ground motion analysis including the magnitude andfrequency spectrum of this event. Enclosure 2 provides an analysis of the resultanteffect upon facility features important to safety.

This seismic event was the minimum level to trigger a Notification of Unusual Event.As this event relates to Diablo Canyon Power Plant, there was no adverse effect topublic health and safety, or upon facility features important to safety.

If you have any questions, please contact me at 805-5454600 or Dr. Lloyd Cluff at415-973-2791.

A member of the STARS (5trategic Teamins and Rewource Sharing) AltianceCallaway -Comanche Peak - Diablo Canyo * Palo Verae -Soth Texas Project * WoLf Creek

0UHL try; UrnlLeU OLdLeS NUL.Ied' tlegUldLOr'; uD DUD e - :iPauec - zi- uj t: ut{IM; Page 3

Document Control DeskOctober 31, 2003Page 2

PG&E Letter DCL-03-141

Sincerely,

Lawrence F. Womack

SWH/A0593059Enclosures

cc: Bruce S. Mallett, Region IVDavid L. Proulx, ResidentGirija S. Shukla, NRRDiablo Distribution

Sent By: United States Nuclear Regulator; 805 595 2355; DeC-29-03 7:07PM; Page 4

Enclosure IPG&E Letter DCL-03-141

Diablo Canyon Power PlantDeer Canyon Earthquakes of October 18, 2003

On October 18, 2003 at 0027 and 0039 PDT, two small local magnitude (ML) 3.4earthquakes occurred. The events are located approximately 5 km east ofDiablo Canyon Power Plant (DCPP), in the region northwest of Deer Canyon.Both earthquakes were felt in the DCPP control room; the second eventtriggered strong motion instruments at the plant site. The earthquakes are partof a sequence of 14 small earthquakes that occurred between October 12 andOctober 24, 2003.

The earthquakes were recorded by the PG&E Central Coast Seismic Network(CCSN) that has operated since 1987 as part of the PG&E Long Term SeismicProgram. The CCSN data are augmented by recordings from the U.S.Geological Survey's (USGS) Northern California Seismic Network (NCSN). TheCCSN consists of 20 seismographic stations, including five dual-gain 3-component stations (large triangles in inset to Figure 1). The addition of theCCSN, including the three-component stations greatly improves the accuracy ofthe earthquake locations in the region around DCPP.

Figure 1 shows the Deer Canyon sequence with previous earthquakes for theperiod 1987 to the present. The October 2003 sequence consists of 14earthquakes with magnitudes ranging from 0.4 to 3.4. The previous seismicityshows scattered activity across the San Luis/Pismo block; the Deer Canyonearthquakes locate within this region of previous activity (Figure 1).

Strong ground motion

The two largest earthquakes were felt in the Unit 1 control room; the operatorsreported that the second event was the stronger. The first event did not triggerthe seismic instruments. The second event did not trigger the Basic SeismicSystem analog recorder (Kinemetrics SMA) in the control room, however theKinemetrics digital recorders (SSA) at the Unit 1 containment base, top ofcontainment, the auxiliary building, and the free-field pit location (near the fitnesstrailer) did trigger on the second event. According to David Castleman ofKinemetrics, Inc., the SMA system worked properly; however, the system did nottrigger because the containment base ground motions contained significantenergy outside the 1.0 to 10.0 Hz bandwidth of the SMA trigger. TheSupplemental System was inoperable at the time of the earthquakes; however,three temporary accelerometers (TerraTech GSR-1 8), located in the Auxiliaryand the Turbine buildings, recorded the second event.

1

OtML Dy;. U[IlLeU OLLdLe5 J4UUltdI nt!uLdLur; dU: Uu DuuD cDD uauec - as - U : uf/ M; Hage 5

Enclosure 1PG&E Letter DCL-03-141

The earthquake force monitor (EFM) located in the control room measured 0.02gon the vertical component. The EFM measurement is from the sensor at theUnit 1 Containment base and does not have the baseline drift removed. Withthe baseline drift removed, the peak acceleration on the vertical component is0.011g.

Table 2 lists the peak accelerations, peak velocities, and peak displacements ofthe free-field and Unit I containment base ground motions after the filtering andbaseline corrections are applied. The peak accelerations range between about1 to 2 percent g with the largest peak acceleration on the vertical component.

Regarding frequency spectrum, the response spectra were computed for thefree-field and Unit 1 containment base recordings. The 5% damped spectra forthe free-field and Unit 1 containment base recordings are shown in Figure 2 and3, respectively. The response spectra for this earthquake show very highfrequency content that is typical for an earthquake of this magnitude. For thefree-field, the horizontal spectra peak at about 12 Hz and the vertical spectrumpeaks at about 20 Hz. For the Unit 1 containment base, the peaks are shifted toslightly smaller frequencies. This shift to lower frequencies is an expected effectof the large foundation.

Conclusions

The occurrence, location, and magnitude of the October 18, 2003 Deer Canyonearthquakes is not a surprise as the sequence of earthquakes is consistent withour understanding of the tectonic framework in the region around DCPP. Theevents occurred in the San Luis/Pismo block, which is a region of previousseismicity. Additional small earthquakes are expected to occur within this block.The ground motions from the second event (0039 PDT) are typical for groundmotions from a magnitude 3.4 earthquake at a distance of 5-0 km.

A detailed report of the Deer Canyon earthquakes, prepared by Dr. NormanAbrahamson and Ms. Marcia McLaren, PG&E Geosciences Department, isavailable upon request.

2

Sent By: United States Nuclear Regulator; 805 595 2355; Dec-29-03 7:07PM; Page 6


-12 1'oO -1 20'45' -1 20 30

36^

MAG~NMUE

- C1li

1.0+

0 2.0+

(: A0+

AU I

A. __ t

j�)0

'U' * U

In

IS .' ,..

t6 10 I

Distance (kNFigure 1. Map and seismic cross section showing the Deer Canyon sequence (orange circles)from October 12 through October 24, 2003 with previous earthquakes (grayed circles) fromOctober 1987 to October 11, 2003. The data were recorded by the PG&E Central Coast Seismicnetwork (large triangles on top figure Inset; triangles with tick marks are 3-component stations)and the Northern Califomia Seismic network (small triangles on top figure inset). Seismic stationsalso are shown on larger map(green triangles). Location of seismic cross section AA' is shown onmap with 8-krn-wide bars to mark events projected on to the cross section In bottom figure.Quaternary faults are from PG&E (1988): selected faults are labeled. The thick gray line Is theboundary of the San Luis/Pismo structural block (Lettis and others, 2001).

3

6erHL by: urn±Leu OLdLeb 1NU.l Li n-yUl iLUI DUD D3D e0DD Ueu - -UI iUIrM; rage 7/11


Frequency (Hz)

Figure 2. Response spectra at 5% damping for the free-field ground motion.

4

Sent By: United States Nuclear Regulator; 805 595 2355; Dec-29-03 7:08PM; Page 8/11


nRuu

]-- I II IN I 11111. I ._ _ - Base of Containment (Honz 1)

n . . a Base of Containment (Vert)..

a %%0.05-

0.04-

:W

6

Q 0.03-

-

0.02-

0.01-

-~ Base of Containment (Honz 2)1 , * * *. T . .. . I I

* I

* a

.a_ ! K I i i i ff i . _ -_--t i 0 i

II

U..

F M

M*

�J'IS

U0

U

a

I."It

.

It

I

0a

Ii a

IJ I9a

liS

4a A

.I- i t I I i i ! tt i _ i _ dX I %Eb~IA

IPI

Ilr "I _ 9^T4

U - I-0I0.1 I 10 100

Frequency (Hz)

Figure 3. Response spectra at 5% damping for the unit Iground motion.

containment base

5

CDn:'-I


Table 1: Earthquake location parameters for the Door Canyon sequence, October 12 to 24, 2003.

Felt events are highlighted in gray.

01st. tOO. P. & G;8p bHWo neOSt orIz. Vemt. No. P-

S-Wave etas. Statlon RIMS No. Sowave Error Error wave flrSt

No. Date Lime (UTC} La1 Lon Depth radings (deg) (km) (seC) MD readingS (k) {km) motions

1 10112/200313:32 28.54 35 11.97 -12048.83 6.6 52 145 3 0.13 2.3 2 0.41 0.39 43

2 10/12/200316:5737.60 3512.28 -12047.59 3.8 6 137 3 0.07 0.5 1 0.66 0.33 5

3 10h17l2003131914.33 3512.49 12047.88.3.6 34 123 3 0.14 1.7 4 0.37 0.17 30

4 A.. Waz ~Z4,8 3 0 . ~ ~ '~9 ltI

2C

CtCt

a

(C

(CC

0C

a

U(IC

N

U

6 10M81200307:40 49.52

7 10/18/20307:41 43:44

8 10W18/200307:55 18.96

9 1 0J202O3 10:38 21.93

10 10l20120O318:22 37.72

11 10/201319:28 31.85

12 10/211200308:3540.18

13 10121/200t313:43 36.44

14 10124/200323:30 52.84

35 12.10

35 12.18

35 12.13

35 12.24

35 12.35

3515.053512A335 12.6535 12.06

-120 47.81-120 47.92

-120 47.88

-120 47.97

-12048.05-12044.37-120 48.00-120 48.20-120 47.73

3.7 6 149

3.7 9 147

3.7 16 132

3.6 9 146

3.8 9 142

8.9 46 50

3.6 24 t25

3.7 37 119

3.4 6 147

4 0.05

4 D.09

4 0.12

4 0.07

3 0.07

4 0.10

3 0.11

3 0.12

4 0.07

0.41.1

1.31.1

0.9

1.51.2

2.60.7

1 0.85

3 0.52

1 0.61

1 0.67

3 0.43

2 0.54

3 0.36

0 0.52

I I V

0.44

0.210.31

0.33

0.61

0.250.170.33

J8

11

7

8

1512416

6

*MD = duratcon magN~tue

Sent By: United States Nuclear Regulator; 805 595 2355; Dec-29-03 7:09PM; page lO/11


Table 2. Peak ground motions values from the Basic Seismic System

digital recorders(after filtering and baseline correction)

Peak Peak Peak,.....

Instrumenttype

Instrumentlocation

Component Peak

Acceleration(a)

PeakVelocity(emls)

PeakDisplacement

(cm)..... .. u . .. 3 0.0 00A

I

KinemetricsSSA

Free field pit(near fitnesstrailer)

Horizontal 1(Channel 1)

Vertical(Channel 2)

I n rwen 0.32V.U'rw0.0100

4- 4 - --0.19 0.00420.022 0.19 0.0042

_ _ 0.1 . o_ _ _A AHorizontal 2(Channel3)

4.. ._

0,011

0.008

0-.19

0.16_.0A77

UM§OU

KinemetricsSSA

Unit 1Containmentbase,89' elev.

Horizontal I(Channel 11-

0.0077

I _ - I - - 0.0080Verticol

(Channel 2)0.012 0.16 0.0060

Horizontal 2If-h..nd. 'QN

-A 40.009 0220.009s 0.22 0.00N4

I_ _ _ _ _ _ I -I. I

7

bient by: unileO .>alLeS ,uc-LbdLi nfYULdLUU1O OUD DtId Ue c-ct -u I. (usrMr rage iiiii


Analysis of The Resultant Effect Upon Facility Features Important To Safety For

The Seismic Event of October 18, 2003

Plant Systems Response:

Per Casualty Procedure (CP) M-4, "Earthquake," a walkdown of the facility was

conducted. All systems continued to operate normally. No visible damage was

discovered. No alarms were received in the control room for the first seismic event;

alarms received in the control room for the second seismic event are as follows:

U-i Alarms

Accumulator 1-3 level high; the accumulator level was high in the normal

operating band (71472%). The alarm came in and out several times, and

returned to normal.Turbine supervisory instrument drawer. Bearing 5 came into alarm and returned

to normal.

U-2 Alarms

Turbine supervisory instrument drawer. Bearing 5 came into alarm and returned

to normal.

Seismic Monitoring Instrumentation Response:

Two seismic events were felt on the plant site this date. The first event was felt at

approximately 0027 with the second one at 0039. CP M4 was entered after the second

event. The first event was felt but did not show any increase on the seismic monitors.

The second event showed approximately 0.02g on the vertical indication of earthquake

force monitor indicator, EFM-1. During the seismic event, the Unit 1 containment base

appeared to have experienced ground motion about 0,02g, based on initial indications,

however the Kinemetrics trigger for the control room alarm did not actuate. The

nominal trigger setpoint for the Kinemetrics trigger is 0.01 g, +/- 0.002g; the maximum

acceleration, after analysis was determined to be 0.011g.

The Kinemetrics trigger instrument calibration performed by the instrument vendor

following this event. The Kinemetric trigger was tested; the as found data was within

specification. In addition, the Kinemetrics trigger switch was found to be within ifs

instrument tolerance and thus operated as designed for this low level event.

Therefore the response the Kinemetrics system and trigger were proper for this low

level event, and were considered operable based on vendor-provided calibration data

and resulting engineering evaluation.

A member of the STARS (Strateg1c Teaming and Resource Sharing) Alliance

Caltaway * Comenche Peak . Diablo Canyon * Palo Verde * South Texas Project . Wof Creel

Pacific Gas and Enclosure 7Electric Company

Lawrence F. Womack Diablo Canyon Power PlantVice President P.Bx5Nuclear Services Avila Beach, CA 934Z4

805.545.4600Fax: 805.545.4234

January 5, 2004

PG&E Letter No. DCL-03-184

U.S. Nuclear Regulatory CommissionATTN: Document Control DeskWashington, DC 20555-0001

Docket No. 50-275, OL-DPR-80Docket No. 50-323, OL-DPR-82Diablo Canyon Units 1 and 2Special Reeport 03-04: San Simeon Earthqua e of December 22, 2003

Dear Commissioners and Staff:

On December 22, 2003, at 1116 PST, with Unit 1 and Unit 2 operating)at 100percent power, a 6.5 magnitude earthquake occurre 1 km northeast of SanSimeon, California. Ground motion was felt and recogni an earthquake bythe control room operators. The earthquake force monitor recorded greater than0.01g for the seismic event. Operations personnel declared an Unusual Event at1122 PST. (Reference NRC Event Notification Number40408.) On December23,2003, at 1212 PST, the Unusual Event was terminated upon confirmation that nodamage to the plant occurred.

This special report is submitted pursuant to Equipment Control Guideline (ECG)51.1, "Seismic Instrumentation." This ECG requires the following actions for aseismic event: for seismic monitoring instruments actuated during a seismic event,"data shall be retrieved from actuated instruments and analyzed to determine themagnitude of the vibratory ground motion. A special report shall be prepared andsubmitted to the Commission ... describing the magnitude, frequency spectrum, andresultant effect upon facility features important to safety."

Enclosure 1 describes the ground motion analysis including the magnitude andfrequency spectrum of this event. Enclosure 2 provides an analysis of the resultanteffect upon facility features important to safety.

As this event relates to the Diablo Canyon Power Plant, there was no adverse effectto public health and safety, or upon facility features important to safety.

If you have any questions, please contact me at 805-545-4600 or Mr. Lloyd Cluff at415-973-2791.

A member of the STARS (Strategic Teaming and Resource Sharing) AllianceCallaway * Comanche Peak * Diablo Canyon * Palo Verde * South Texas Project - Wolf Creek

Document Control Deskj January 5, 2004

7 Page 2

PG&E Letter DCL-03-18 4

Sincerely,

Z.:Z KZ-,Lawrence F. Womack

SWH/A0597032Enclosures

cc: Bruce S. Mallett, Region IVDavid L. Proulx, ResidentGirija S. Shukla, NRRDiablo Distribution


San Simeon Earthquake of December 22, 2003

Introduction

On December 22, 2003 at 1116 PST a strong earthquake of moment magnitude (Mw)6.5 struck the central coast region. The earthquake, called the San SimeonEarthquake, was located approximately 50 km NNW of Diablo Canyon Power Plant(DCPP), in the region 11 km northeast of San Simeon, at a depth of about 7 km. TheSan Simeon Earthquake is the largest earthquake measured in the San Simeon region.The second largest earthquake in this region was the 1952 Bryson Earthquake of localmagnitude (ML) 6.2, approximately 8 km north of the 2003 epicenter. The San SimeonEarthquake was widely felt from Los Angeles to San Francisco. Earthquake groundeffects included landslides and related ground failure near the epicenter, however nosurface faulting was observed. Most of the damage occurred in Paso Robles, 39 kmENE of the epicenter. Two deaths have been confirmedi due to a building collapse.The earthquake was also strongly felt at DCPP in the Administration Building and theControl Room. Strong motion instruments at the plant site were triggered.

The main shock initiated a rupture at a depth to the southeast and triggered a vigorousaftershock sequence that extends about 30 km southeast of the main shock. As ofDecember 26, 2003, approximately 960 aftershocks have occurred, including about 120magnitude (M) 3 events and 19 M 4 earthquakes. During the first 24 hours, the activitywas about 50 percent higher than the average for a California sequence according tothe US Geological Services online report, December 24, 2003, (httP://www.uss.Qov/).

The San Simeon Earthquake was a reverse fault event beneath the Santa LuciaMountains. It occurred along a NW-SE trending fault plane that dips either to the SWor NE. This is a common fault mechanism along this trend. (Reference 1).

Figure 1 shows the location of the main shock and first 20 hours of aftershocks. Thereis concentrated activity near the main shock and at the southeast end of the aftershockzone. Most of the aftershocks near the main shock are located between the Oceanicand Nacimiento fault zones, whereas the earthquakes to the southeast are not asconstrained by the faults. It is not clear which fault, if either, was the cause of theearthquake. The aftershock patterns in depth view (Figure 1, cross sections A' andBB') show diffuse activity above the main shock and no obvious fault plane. Theclosest distance from the aftershock zone to DCPP is about 38 km.

Strong Ground Motion

The main shock was felt in the Units 1 and 2 Control Room. It triggered the basicseismic system analog recorder (Kinemetrics SMA) in the Control Room and theKinemetrics digital recorders (SSA) at the Unit 1 containment base, top of containment,the Auxiliary Building, and the free field pit locations (near the Fitness Trailer). Thesupplemental system was out of service at the time of the earthquake, however, threetemporary accelerometers located in the Auxiliary and Turbine Buildings and a

1

Enclosure 1PG&E Letter DCL-03-18 2

permanent instrument in the basement of the 500 kV Switching Center triggered. Thesupplemental system is currently inoperable and replacement parts are obsolete; boththe basic and supplemental systems are scheduled to be replaced in January 2004 withnew instrumentation.

The earthquake force monitor (EFM) located in the control room measured 0.04g on thehorizontal component. The EFM measurement is from the sensor at the Unit 1containment base and does not have the baseline drift removed. With the baselineshift removed (but prior to filtering), the peak acceleration on the horizontal componentis 0.042g. Table 1 lists the peak accelerations, peak velocities and peak displacementsof the free-field and Unit 1 containment base ground motions after filtering and baselinecorrections are applied. The peak accelerations range between 0.02g and 0.05g, withthe largest peak acceleration in the free field, horizontal 2 direction.

Regarding the frequency spectrum, the response spectra were computed for thefree-field and Unit 1 containment base recordings. The 5 percent damped spectra forthe free-field and Unit 1 containment base recordings are shown in Figures 2 and 3,respectively. The response spectra for this earthquake show a typical spectral shapefor rock sites.

For the free-field, both horizontal spectra and the vertical spectra peak at 4 to 5 Hz.These peaks of the free-field spectra are lower than expected for a magnitude 6.5reverse earthquake recorded at 38 km distance. Current attenuation relations for rocksite yield median horizontal spectral accelerations that are 1.5 to 2 times larger than therecorded free-field spectra. For the Unit 1 containment base, the spectra peak at 3 to 4Hz for all three components. The containment base spectra show amplification in this 3to 4 Hz range as compared to the free-field spectra. At short frequencies (< 2 Hz), thespectra from the containment base are similar to the free-field spectra. At highfrequencies (e.g. 10 Hz), the horizontal spectra from the containment base are smallerthan the free-field spectra.

Conclusions

The San Simeon Earthquake is the largest measured in the San Simeon region. Thereverse fault motion of the main shock and aftershocks and the aftershock patterns areconsistent with previous seismic activity in this region. The free-field ground motionsrecorded at DCPP are below then median ground motion estimated for this event usingcurrent attenuation relations for rock sites.

Dr. Norman Abrahamson and Ms. Marcia McLaren of PG&E Geosciences Departmentare preparing a detailed report of the San Simeon earthquake. The report will includeanalyses of the Kinemetrics SMA tape system. The detailed report will be availableupon request

2


Reference

(1) McLaren, M. K. and Savage, W. U. (2000). Seismicity of South-Central CoastalCalifornia: October 1987 through January 1997, Bull Seism. Soc. Am. 91, no. 6, pp.1629-1658.

3


-120.5-1 21.5

36 -

\35.75 -

35.5 -

\35.25-

-121.25 -121 -120:75

MAGNITUDES

* 0.0+1.0+

o 2.0+O 3.0+* 4.0+3 5.0+

* 6.0+

C' 3.0+* 4.0+

35

I Oceanic NacimientoJ .. . I I .

S.~C8t

u-W-qtow e -

- V&-befiA'

0 10 -

0 -

-20-

HosgriI,

Oceanic Nacimiento_ .3 . . 1_,

oolo

00 a

B'

is -

20-

25- 4 25,

0 455 10 I5 20 25 20 35 40

Distance (km)0 5 10 IS 20 25 J0 3S 40 4S S0

Distance (km)

Figure 1. San Simeon Earthquake (large red circle) of 22 December 2003, 19:15 GMT,and aftershocks to 23 December 2003, 14:51 GMT. Nearby fadults are labeled.Diamond earthquake symbols are preliminary locations form the USGS website;; circlesare events that have been reviewed by USGS seismologists NCEDC. Seismicity crosssections AA' and BB' are also shown.

4


Table 1. Peak ground motions values from the Basic Seismic System digitalrecorders (after filtering and baseline correction).

Instrument Instrument Component Peak Peak Peaktype location Acceleration Velocity Displaceme

( cmls) c k m)nt

KinemetricsSSA

Free field pit(near FitnessTrailer)


0.034 8.3 7.4_~ _-1 -

Vertical(Channel 2)

0.022 7.6 6.3


0.046 8.2 4.91-

KinemetricsSSA

Unit 1Containmentbase,89' elev.

i f . IHorizontal 1(Channel 1)

0.033 8.2 7.6

Vertical 0.036 8.1 i 6.3(Channel 2) _I _Horizontal 2(Channel 31s

0.041 7.9 1 5.0J '-----. -, I ___________ I I �-

5

Enclosure 1PG&E Letter DCL-03-1 82

C 0.10

a0.0.

(n

I II ,I

Frequency (Hz)

Figure 2. Response spectra at 5% damping for the free-field ground motion.

6


Frequency (Hz)

Figure 3. Response spectra at 5% damping for the unit 1 containment base groundmotion.

7


Analysis of The Resultant Effect Upon Facility Features Important To Safety ForThe San Simeon Earthquake of December 22, 2003

Plant Systems Response:

The San Simeon Eearthquake registered 0.04g at the plant site, as read by theearthquake force monitor (EFM). The duration of the main shock was approximately22 seconds. During this time, numerous alarms were received on both units. Many ofthe alarms were associated with movement of fluid levels in various systems. Whenthe seismic activity stopped, the alarms that were received cleared and returned tonormal. Operations responded by dispatching people into the power plant to visuallyverify systems that had received level alarms. Examples of the level alarms include;spent fuel pools, electro-hydraulic (EH) control system, and startup transformer 1-1.Operations took action to restore the operation of the Unit 2 EH pumps that had trippedoff line due to a low-low system level lockout. This low-low system level lockout wasdue to the motion of the EH fluid; there were no leaks from the system. All otherinvestigations to alarms revealed no leakage from systems and no damage caused bythe earthquake. It was noted that the seismically-induced wave action in the Unit 1spent fuel pool was of sufficient magnitude to cause a small amount of water to splashup onto the surrounding deck of the pool. Plant personnel were dispatched to cleanthis area.

Per Casualty Procedure (CP) M4, "Earthquake," a walkdown of the facility wasconducted. All systems continued to operate normally. No visible damage wasdiscovered. Operations personnel performed inventory checks required by CP M4; nosystems were found to be leaking as a result of the earthquake. DCPP FireDepartment personnel conducted plant walkdowns, including both containmentstructures to verify the continued integrity of fire protection features. No observabledamage was discovered within the power plant and containment structures. No fireprotection impairments were found. Operations personnel also performed an inventoryof the diesel fuel oil storage tanks. No abnormalities were observed.

Seismic Monitoring Instrumentation Response:

The main shock triggered the basic seismic system analog recorder (Kinemetrics SMA)in the Control Room and the Kinemetrics digital recorders (SSA) at the Unit 1containment base, top of containment, the Auxiliary Building, and the free-field pitlocations (near the Fitness Trailer). The supplemental system was inoperable at thetime of the earthquake, however, three temporary accelerometers located in theAuxiliary and Turbine Buildings and a permanent instrument in the basement of thecontrol room at the 500 kV Switching Center triggered. The EFM located in the ControlRoom measured 0.04g on the horizontal component

All functional seismic monitoring instrumentation operated as designed.

1

Enclosure 8

M

San Simeon Earthquake


Public Meeting

Embassy Suites, San Luis Obispo,

February 4, 2004

1

M

Agenda for PG&E'sPresentation

* Diablo Canyon Seismic Design* Design History& Design Basis* Long-Term Seismic Program (LTSP)

* San Simeon Earthquake• What occurred in context (historical seismic activity in SLO)* Comparison with LTSP Tectonic Framework (model)* "Blind Faults"* Plant structural performance in event

* Chronology & Lessons Learned* Event chronology & plant response• Equipment performance* Lessons Learned

* Conclusions

2

San Simeon EarthquakeKey Points

* Diablo Canyon has a very robust earthquake design* San Simeon earthquake typical for area* Ground response at Diablo Canyon less than

predicted for event - insignificant relative to design* Diablo Canyon structures performed as expected* PG&E's response was thorough - no damage* Incorporating lessons learned

3


Diablo Canyon Seismic Design Basis

and Design History

Lawrence F. Womack,

Vice President - Nuclear Services

4

Seismic Design Bases

* DE: 0.20 g (horizontal)

* Seismic Trip: 0.3g* DDE: 0.40 g (horizontal)

* HOSGRI: 0.75 g (horizontal)* LTSP - Probabilistic and Deterministic

studies for adequacy of design margins

IIc J.

Seismic Design History

* Original Design, 1967 - Earthquake design criteriadeveloped by Blume

* HOSGRI (HE), 1977 - 7.5 magnitude earthquakeon the Hosgri Fault. NRC and PG&E agree on Hosgri evaluation criteria

combining both Newmark's and Blume's versions ofHosgri response spectra

6

Seismic Design History (cont.)

* Long Term Seismic Program, 1984 and on - LivingProgram which:* Seven year re-evaluation of the geology, geophysics,

seismology, ground motion, soils-structure interaction,structural performance, and assessment of seismicmargins through deterministic and probabilistic riskassessment

. NRC approval in 1991 including USGS review

• Evaluates new information - world-wide

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Executive Summary Page 7

Figure 1

Map of regional faults and tectonic setting of the south-central California coastal region.SLBF is San Luis Bay fault; PF is Pecho fault. Structural blocks in inset map are SAL, Salinian;

CAM, Cambria; SLP, San Luis/Pismo; SMV, Santa Maria Valley; CAS, Casmalia; VSY, VandenburgSanta Ynez Valley; SH, Solomon Hills; PH, Purisma Hills.

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Executive Summary Page 7

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Figure 1

Map of regional faults and tectonic setting of the south-central California coastal region.SLBF is San Luis Bay fault; PF is Pecho fault. Structural blocks in inset map are SAL, Salinian;

CAM, Cambria; SLP, San Luis/Pismo; SMV, Santa Maria Valley; CAS, Casmalia; VSY, VandenburgSanta Ynez Valley; SH, Solomon Hills; PH, Purisma Hills.

I I i -

EXPLANATION

0

0

Event location that ispoorly constrained

Event location that iswithin 20 km andgenerally within 10 km

MAGNITUDES

000

5.0- 5.9

6.0- 6.9

7.0- 7.9

(a)122 30' 121 30' 120

-- 19"O36

X &95V\ l% EXPLANATION

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earthquakes poorly constrained30' 10

Q Event location that iswithin 20 km andgenerally within 10 km

35 -1827 MAGNITUDES

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30'

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Is-Gs50' 30O 121 30' 120

36

30'

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a

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0MAGNITUDES

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o 1.0 -1.9

o 2.0 - 2.9

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0

0

From McLaren and Savage, 2001

36 -I36! .5-1 1- 0 )-2 .36 36

35.75

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Distance (km)

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Frequency (Hz)

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Chronology of Events & Lessons Learned

James R. BeckerVice President - Diablo CanyonOperations and Station Director

34

Chronology of Events

* Both units were at full power

* 11 16 PST, December 22, 2003, San Simeonearthquake occurred

* Implemented Procedure M-4 "Earthquake"

* Unit 2 Electro-Hydraulic pumps locked out andwere restarted

* Operations, Engineering, and Safety Teamsdispatched throughout power block

35

Chronology of Events (cont.)

* Earthquake Force Monitor read 0.04 g's.

* Notification of Unusual Event declared at1122- County and NRC notified, Liaison to the County

* Control room and plant walkdownscompleted - no damage observed

36

Lessons Learned

* An Event Response Team was formed tocapture lessons learned and recommendimprovements

* Multi-discipline Team of Operations,Training, Engineering, and Maintenance

* Ongoing Effort to Learn from this event

37

Lessons Learned Focus Areas

* Personnel Safety

* Procedure Revisions

* Emergency Plan Implementation

* Training

* Plant Systems Response - Operations

* Plant Systems Response - Engineering

38

Lessons Learned Focus Areas

* Plant Response - Civil Engineering andGeosciences

* Security Actions

39


Conclusions

David H. Oatley,

Vice President - General Manager

40

San Simeon EarthquakeConclusions

* Diablo Canyon has a very robust earthquake design* San Simeon earthquake typical for area* Ground response at Diablo Canyon less than

predicted for event - insignificant relative to design* Diablo Canyon structures performed as expected* PG&E's response was thorough - no damage* Incorporating lessons learned

41