Text

Summary of Public Meetings with Pacific Gas & Electric Company Re Results of Special Report Submitted Following 12/22/2003 Earthquake Near San Simeon, California & NRC Inspection Conducted Following Earthquake
	ML040440460
Person / Time
Site:	Diablo Canyon
Issue date:	02/13/2004
From:	William Jones; NRC/RGN-IV/DRP/RPB-E
To:	Rueger G; Pacific Gas & Electric Co
References
	Download: ML040440460 (102)
	v • d • e

UNITED STATES NUCLEAR REGULATORY COMMISSION REGION IV 611 RYAN PLAZA DRIVE, SUITE 400 6' ARLINGTON, TEXAS 76011-4005 February 13, 2004 Gregory M. Rueger, Senior Vice President, Generation and Chief Nuclear Officer Pacific Gas and Electric Company Diablo Canyon Power Plant P.O. Box 3 Avila Beach, California 93424

SUBJECT:

MEETING

SUMMARY

FOR THE TWO FEBRUARY 4, 2004, PUBLIC MEETINGS

Dear Mr. Rueger:

This refers to the two public meetings conducted at the Embassy Suites Hotel in San Luis Obispo, California, on February 4, 2004. The first meeting was a technical meeting to discuss the results of the Special Report submitted following the December 22, 2003, earthquake near San Simeon, California. During the second meeting NRC provided a detailed interim exit of an NRC inspection conducted following the December 22 earthquake. The meeting attendance list and a copy of the material discussed during the meeting are enclosed. The meeting was transcribed and the transcript will be provided at a later date. The NRC will review the transcript to 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 of Federal Regulations, a copy of this letter and its enclosure will be available electronically for public inspection in the NRC's Public Document Room or from the Publicly Available Records (PARS) component of NRC's document system (ADAMS). ADAMS is accessible from the NRC Web site at httR://www.nrc.gov/reading-rm/adams/index.html (the Public Electronic Reading Room).

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

Sincerely, William B. Jones, Chief Project Branch E Division of Reactor Projects Dockets: 50-275 50-323 License: DPR-80 DPR-82

Pacific Gas and Electric Company

Enclosures:

1. Attendance List

2. Background Information

3. Excerpts for NRC Integration Inspection Report 05000275/2003008 and 05000323/2003008

4. Preliminary Result of NRC Event Followup for the December 22, 2003, San Simeon Earthquake

5. Preliminary Report on December 22, 2003, San Simeon Earthquake

6. Special Report 03-03: Seismic Event of October 18, 2003

7. Special Report 03-04: San Simeon Earthquake of December 22, 2003

8. PG&E Presentation cc w/enclosures:

David H. Oatley, Vice President and General Manager Diablo Canyon Power Plant P.O. Box 56 Avila Beach, CA 93424 Lawrence F. Womack, Vice President, Power Generation & Nuclear Services Diablo Canyon Power Plant P.O. Box 56 Avila Beach, CA 93424 James R. Becker, Vice President Diablo Canyon Operations and Station Director, Pacific Gas and Electric Company Diablo Canyon Power Plant P.O. Box 3 Avila Beach, CA 93424 Sierra Club San Lucia Chapter c/o Henriette Groot 1000 Montecito Rd.

Cayucos, CA 93430 Nancy Culver San Luis Obispo Mothers for Peace P.O. Box 164 Pismo Beach, CA 93448 Chairman San Luis Obispo County Board of Supervisors Room 370 County Government Center San Luis Obispo, CA 93408

Pacific Gas and Electric Company Truman Burns\Robert Kinosian California Public Utilities Commission 505 Van Ness Ave., Rm. 4102 San Francisco, CA 94102-3298 Diablo Canyon Independent Safety Committee Robert R. Wellington, Esq.

Legal Counsel 857 Cass Street, Suite D Monterey, CA 93940 Ed Bailey, Radiation Control Program Director Radiologic Health Branch State Department of Health Services P.O. Box 942732 (MS 178)

Sacramento, CA 94234-7320 Richard F. Locke, Esq.

Pacific Gas and Electric Company P.O. Box 7442 San Francisco, CA 94120 City Editor The Tribune 3825 South Higuera Street P.O. Box 112 San Luis Obispo, CA 93406-0112 James D. Boyd, Commissioner California Energy Commission 1516 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, 2004 6:30 p.m.

LOCATION Embassy Suites Hotel NAME (PLEASE PRINT) ORGANIZATION CATEGORY 1 CATEGORY 3 lC"M a 14 ,. . .

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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, 2004 6:30 p.m.

LOCATION Embassy Suites Hotel NAME (PLEASE PRINT) ORGANIZATION CATEGORY 1CATEGORY 3

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Enclosure 2 BACKGROUND INFORMATION FOR AR Re CO 0 "I

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February 4, 2004 6:30 pm.

Public Meetings

AGENDA to the Nuclear Regulatory Commission's Two separate meetings will be held in regardPower Plant response to the San Simeon inspection and review of the Diablo Canyon the results of technical meeting (Category 1) to discuss earthquake. The first meeting will be a 22, 2003, submitted following the December Pacific Gas and Electric's Special Report on the near San Simeon, California. Immediately following the technical meeting interim earthquake 3) will be conducted to provide a detailed Special Report, a second meeting (Category the December 22, 2003, earthquake.

exit of an NRC inspection conducted following have one is invited to observe this meeting and will Category 1 Technical Meeting: The public but before the the NRC after the business portion, or more opportunities to communicate with meeting is adjourned.

Open meeting at 6:30 pm

Conduct of Meeting: Nuclear Regulatory Commission

Introductions: Nuclear Regulatory Commission

Introductions: Pacific Gas and Electric Participants

Opening Remarks: Nuclear Regulatory Commission

Opening Remarks: Pacific Gas and Electric

Discussions: Special Report to December 22, 2003, San Simeon Earthquake

Comments and Questions: Meeting attendees

Adjourn Meeting tailored for the public to comment and ask Category 3 meeting: The meeting is specifically questions throughout the meeting.

Open meeting following break Conduct of Meeting: Nuclear Regulatory Commission

Introductions: Nuclear Regulatory Commission Review of Interim Exit Results: David Proulx

Questions and Comments: Meeting Attendees to Adjourn meeting at 9:30 pm The NRC staff will make themselves available

adjournment of members in the audience following this meeting.

Seismic Acceleration 0.8 I 0.7 -

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Hosgri Double Design Design San Simeon Earthquake

Enclosure 3 C VUNITED STATES iNUCLEAR REGULATORY COMMISSION REGION IV

-i 611 RYAN PLAZA DRIVE, SUITE 400 ARLINGTON, TEXAS 76011-400 January 30, 2004 Gregory M. Rueger, Senior Vice President, Generation and Chief Nuclear Officer Pacific Gas and Electric Company Diablo Canyon Power Plant P.O. Box 3 Avila Beach, CA 93424

SUBJECT:

DIABLO CANYON POWER PLANT - NRC INTEGRATED INSPECTION REPORT 05000275/2003008 AND 05000323/2003008

Dear Mr. Rueger:

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

This inspection examined activities conducted under your licenses as they relate to safety and compliance with the Commission's rules and regulations and with the conditions of your licenses.

The inspectors reviewed selected procedures and records, observed activities, and interviewed personnel.

There were five findings of very low safety significance (Green) identified in this report. Four of the findings were NRC-identified and one was self-revealing. Four of these findings involved violations of NRC requirements. However, because of their very low safety risk significance and because they are entered into your corrective action program, the NRC is treating these four findings as noncited violations (NCVs) consistent with Section Vl.A of the NRC Enforcement Policy. If you contest any NCV in this report, you should provide a response within 30 days of the date of this inspection report, with the basis for your denial, to the U.S. Nuclear Regulatory Commission, ATTN: Document Control Desk, Washington, DC 20555-0001; with copies to the Regional 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. Nuclear Regulatory Commission, Washington, DC 20555-0001; and the NRC Resident Inspector at the Diablo Canyon Power Plant.

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

Pacific Gas and Electric Company 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) will be documented in NRC Inspection Report 05000275;323/2004002, to be issued approximately at the end of April 2004.

On January 16, 2004, we provided you with some preliminary results of the NRC's event followup for the December 22, 2003, San Simeon earthquake. (ADAMS Accession ML040160653). That letter provided the preliminary results of the inspection activities (Phases 1 and 2) conducted through January 9, 2004, and provided the scope for Phase 3 of the NRC's actions that are ongoing. The Phase 3 activities will involve additional planned inspections, including the visual inspections in Unit 1 containment during the March 2004 refueling outage and further review of your 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 public observation and will provide attending members of the public a period for comments and questions prior to the conclusion of the meeting.

Pacific Gas and Electric Company operated under voluntary bankruptcy proceedings during this inspection period. The NRC has monitored plant operations, maintenance, and planning to better understand the impact of the financial situation and how it relates to your responsibility to safely operate the Diablo Canyon reactors. NRC inspections, to date, have confirmed that you are operating 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 its enclosure will be available electronically for public inspection in the NRC Public Document Room or from the Publicly Available Records System (PARS) component of NRC's document system (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/

William B. Jones, Chief Project Branch E Division of Reactor Projects Dockets: 50-275 50-323 Licenses: DPR-80 DPR-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 Plant Units 1 and 2; Fire Protection, Maintenance Effectiveness, Postmaintenance Testing, ALARA Planning and Controls, Problem Identification and Resolution.

This report covered a 14-week period of inspection by resident inspectors and announced inspections in emergency preparedness and radiation protection and followup inspections to the October 18 and December 22, 2003, earthquakes. Specifically, Section 1R1 4.1 documents the followup inspections performed in response to earthquakes impacting the Diablo Canyon Power Plant. The NRC identified four Green noncited violations and one Green finding. The significance of most findings is indicated by their color (Green, White, Yellow, or Red) using Inspection Manual Chapter 0609, "Significance Determination Process." Findings for which the Significance Determination Process does not apply may be Green or be assigned a severity level after NRC management review. The NRC's program for overseeing the safe operation of commercial 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.d which requires written procedures be established, implemented, and maintained covering the Fire Protection Program implementation. Specifically, PG&E failed to adequately establish and implement procedural changes that provided for senior control operators, licensed control operators, and nonlicensed, Level 8 nuclear operators to serve in the operator responder position. The inspectors noted that the applicable attachment to the procedure for conduct of the operations response position was not established until after training had been provided on implementing the procedure. Operations' responders supporting the fire brigades exhibited a knowledge weakness in activities such as communications with the control room, manual actuation of fire suppression equipment, and providing information to the fire brigade regarding safe shutdown equipment.

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

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

Green. The inspectors identified a noncited violation for the failure to adequately monitor the performance of the Unit 1 auxiliary feedwater system in accordance with 10 CFR 50.65(a)(2). Specifically, the unavailability time performance criteria for 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 the availability and reliability of the auxiliary feedwater system to respond to initiating events. The finding is greater than minor using Example 1.f of Inspection Manual Chapter 0612, Appendix E. Similar to the example, the inspectors identified that Pacific Gas and Electric did not consider unavailability time for the Unit 1 auxiliary feedwater system, although the unavailability time was due to prior poor maintenance practices on Valve FW-1 -FCV-437. If the unavailability time was considered, the 10 CFR 50.65(a)(2) evaluation would be invalid. Using the Significance Determination Process Phase I worksheet in Inspection Manual Chapter 0609, Appendix A, the finding is of very low safety significance, since there was no loss of an actual safety function, no loss of a safety-related train for greater than the Technical Specification allowed outage time, and the finding is not potentially risk significant due to a seismic, fire, flooding, or severe weather initiating event (Section 1R12).

Green. The inspectors identified a noncited violation of 10 CFR Part 50, Appendix B, Criterion l1l, when Pacific Gas and Electric personnel failed to adequately evaluate the capability of core exit thermocouples to measure the radial temperature gradient for Quadrant 1 of the Unit 1 reactor core. Specifically, maintenance personnel inadvertently swapped core exit thermocouples at a connection, leaving only three operable thermocouples per Trains A and B for Quadrant 1. When questioned by the inspectors, engineering personnel could not provide an adequate technical bases for how measurement of radial temperature gradient could be accomplished.

The finding impacts the mitigating system cornerstone through degraded overall availability of the components within a system used to assess and respond to initiating events to prevent undesirable consequences. The finding was greater than minor when compared to Example 3.a of Inspection Manual Chapter 0612, Appendix E. Similar to Example 3.a, Pacific Gas and Electric performed additional work to verify the ability of the core exit thermocouples to measure radial temperature gradient within Quadrant 1 of the Unit 1 reactor core. Using the Significance Determination Process Phase 1 screening worksheet from Inspection Manual Chapter 0609, Appendix A, the finding was determined to be of very low Enclosure

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

Green. A self-revealing violation of 10 CFR Part 50, Appendix B, Criterion XVI, was identified for failure to promptly identify and correct a condition adverse to quality.

Specifically, in December 2000, Pacific Gas and Electric failed to identify and correct the population of Rockwell-Edwards valves in safety-related and risk-significant systems that were susceptible to failure of the packing gland follower flange from intergranular stress corrosion cracking. Pacific Gas and Electric received an industry notification in December 2000 that Rockwell-Edwards valves were vulnerable for this type of failure, but initiated corrective actions on a very limited population of valves (those involving a trip risk). As a result, on December 3, 2003, the packing gland follower flange for safety injection Valve SI-1 -8890A (pressure equalization valve) on the hot leg injection line failed, due to intergranular stress corrosion cracking, resulting in excessive packing gland leakage.

The finding impacted the mitigating systems cornerstone through degraded equipment performance for a system train that responds to initiating events to prevent undesirable consequences. The finding is greater than minor because the finding would become a more significant safety concern if the valve condition was left uncorrected. The amount of leakage from the valve would be significantly greater than a 30 drop per minute leak rate, if the safety injection pumps were fully running in the hot leg injection mode. The Valve Sl-1-8890A leak rate is bounded by a residual heat removal pump seal failure. Pacific Gas and Electric concluded the safety injection system was operable but degraded because both safety injection system trains would be available to provide adequate flow if a demand occurs. Using the Significance Determination Process Phase 1 worksheet in Inspection Manual Chapter 0609, Appendix A, the finding was determined to be of very low safety significance, since there is no loss of an actual safety function, no loss of a safety-related train for greater than the Technical Specification allowed outage time, and the finding is not potentially risk significant due to a seismic, fire flooding, or severe weather initiating event (Section 40S2.2)

Cornerstone: Occupational Radiation Safety

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

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

process) and affected the associated cornerstone objective (to ensure adequate protection of workers' health and safety from exposure to radiation). This occurrence involved inadequate planning which resulted in unplanned, unintended occupational collective dose for the work activity. When processed through the Occupational Radiation Safety Significance Determination Process, this finding was found to have no more than very low safety significance because the finding was an as low as is reasonably achievable planning issue and Pacific Gas and Electric Company's 3-year rolling average collective dose was less than 135 person-rem (Section 20S2).

B. Licensee-Identified Violations None.

Enclosure

CONTENTS PAGE

SUMMARY

OF FINDINGS . ...................................................... 1 REACTOR SAFETY 1R04 Equipment Alignments ............ .................................. 1 1R05 Fire Protection . .................................................... 3 1R06 Flood Protection ............ ..................................... 7 1R11 Licensed Operator Regualification ..................................... 8 1R12 Maintenance Effectiveness ............... .......................... 8 1R13 Maintenance Risk Assessments and Emergent Work Control ..... .......... 11 1R14 Operator Performance during Nonroutine Evolutions and Events, Including Followup Response to Earthguakes Impacting Diablo Canyon Power Plant .... 12 1R16 Operator Workarounds ............ ................................. 17 1R19 Postmaintenance Testinq ........... ................................ 17 1R22 Surveillance Testing ............. .................................. 20 1R23 Temporary Plant Modifications ....................................... 21 1EP2 Alert Notification System Testing ..................................... 21 1EP3 Emergency Response Organization Augmentation Testing ..... ............ 22 1EP4 Emergency Action Level and Emergency Plan Changes ..... .............. 22 1EP5 Correction of Emergency Preparedness Weaknesses and Deficiencies .... ... 23 1EP6 Emergency Preparedness Evaluation ................................. 24 RADIATION SAFETY 20S2 ALARA Planning and Controls ....................................... 24 OTHER ACTIVITIES 40A1 Performance Indicator Verification .................................... 26 40A2 Identification and Resolution of Problems .............................. 27 40A3 Event Followup . .................................................. 30 40A4 Crosscutting Aspects of Findings .................................... 31 40A5 Other ........................................................... 31 40A6 Management Meetings ............ ................................. 32 ATTACHMENT: SUPPLEMENTAL INFORMATION Key Points of Contact .................... ............................... A-1 Items Opened, Closed, and Discussed ..................................... A-1 List of Documents Reviewed ............ ................................. A-2 List of Acronyms . ...................................................... A-5 Enclosure

Unit 1, maintenance outage windows for Component Cooling Water Heat Exchanger 1-2, Atmospheric Dump Valve MS-1 -PCV-1 9, and Positive Displacement Pump 1-3 on September 30

Unit 2, Eagle 21 Protection Set Rack 13 Nonvolatile Random Access Memory replacement 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 to minimize the probability of initiating events, maintain the functional capability of mitigating systems, and maintain barrier integrity. The scope of work activities reviewed includes troubleshooting, work planning, plant conditions and equipment alignment, tagging and clearances, and temporary modifications. The following activities were observed during this inspection period:

Unit 2, Valve FCV-495 actuator replacement

Unit 1, Valve SI-1-8890 packing leakage

b. Findings No findings of significance were identified.

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

a. Inspection Scope The inspectors reviewed three inspection samples (two earthquakes and high Pacific Ocean swells) of nonroutine evolutions or events.

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

Background

Enclosure

Diablo Canyon Power Plant is located in a seismically active area along the interface of the Pacific and North American Plates. Several faults are located within 50 miles of the plant. PG&E is required by the operating license to maintain a Long-Term Seismic Program to reevaluate the seismic design bases against insights and knowledge gained with each seismic event. FSAR Update Section 3.7 describes the seismic design basis of the 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 to continue to operate. This value is ground motion acceleration at the containment base of 0.2g. The Double Design Earthquake, equivalent to a "Safe Shutdown Earthquake," is the design 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 an earthquake originating in the Hosgri fault. This evaluation ensures the plant can be safely shut down if the expected maximum ground motion were to occur.

Technical Specification 3.3.1, "Reactor Trip System," requires instrumentation to initiate a reactor 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 of ground acceleration. Procedure CP M-4, "Earthquake," Revision 18, addresses the actions 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 a Notification of Unusual Event (NOUE) because an earthquake that measured 3.4 was felt by the control room operators. No damage to plant equipment was observed and both units remained at 100 power throughout the event.

A preshock occurred at 12:27 a.m. that lasted approximately 3 seconds and was felt by the control room operators. No alarms or other effects were noted. The primary shock occurred at 12:39 a.m. and lasted approximately one second. The epicenter of the seismic event 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 high vibration alarms on both units and a high level alarm on the Unit 1 Safety Injection Accumulator 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, which contained instructions for response to earthquakes detected at the site. The shift manager initiated a preliminary evacuation of the intake structure (where valve maintenance was in progress) until the extent of the seismic event was understood. PG&E performed walkdowns of both containments and all vital areas to ensure no immediate structural damage was evident. PG&E performed enhanced monitoring of safety-related tank levels to ensure no ruptures occurred. No damage to any plant equipment was identified.

Enclosure

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

The inspectors reviewed Special Report 50-275;323/03-03-00, "Seismic Event of October 18, 2003," which discussed the Deer Canyon earthquakes of October 18 and provided analysis of the effects of the earthquakes on plant structures, systems, and components. The inspectors found the report properly analyzed the seismic data and the impact 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 a noise on the roof of the Diablo Canyon administrative building. The inspectors responded to the control room to report this information to the shift manager. The shift manager received similar reports from personnel in the warehouse and the training building outside the protected area. The inspectors and the operators verified that no alarms were received in the control room and that the seismic monitor did not register this event. The shift manager and the inspectors reviewed Procedure CP M-4 and verified that no action was required.

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

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

The SRI reported to the control room to observe PG&E actions. The inspectors verified that the requirements of Procedure CP M-4 were followed. The procedure required verification of the tank levels of all of the major safety-related tanks to ensure that no catastrophic failures of the important tanks had occurred. The inspectors verified the applicable 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

accumulator high and low levels for both units during the seismic event because of sloshing of the water. Operators received temporary alarms that included high vibration for the Unit 1 turbine. The operating electrohydraulic control pump tripped and was immediately 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 the required calls to the state and local officials. PG&E sent personnel to the Emergency Operating Facility (EOF), which is co-located with the San Luis Obispo County Office of Emergency Services to assist in monitoring the community and the emergency services response. PG&E established a video conference between the EOF and the shift manager's office for the next 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . One of the inspectors was present in the shift manager's office during each of the updates between the EOF and the control room. The EOF 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 local roadways to Region IV. Highways 46 and 41 had debris on the road, and Highway 46 experienced some buckling, but the highways were passable for emergency response purposes. In addition, personnel in the EOF communicated the status of several emergency sirens that were inoperable because of the power outages in San Luis Obispo county.

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 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, four sirens were without power. The remaining four were restored in the subsequent 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

The inspectors monitored reports of PG&E walkdowns of the plant. At approximately 3 p.m., the Rls began independent inspections of plant equipment, for Phase I of the NRC inspection plan following the earthquake. One RI remained in the control room to monitor operator actions and maintain communications within the agency, while the other inspector walked 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 this building. The inspectors verified that no leaks existed in the safety-related systems and that no cracks were evident in structural members.

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

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

Enclosure

The inspectors entered the fuel building and verified the level in the spent fuel pools. All structural elements in the spent fuel pool were unaffected. Spent fuel pool water clarity was good. No cracks were evident in the fuel building ventilation system or structural members.

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

The Rls provided continuous site coverage until PG&E exited the NOUE. Because the area continued to experience aftershocks, PG&E elected to remain in a NOUE for approximately 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . The Rls continued to inspect the facility and monitor control room actions for the duration of the NOUE. During the evening, the inspectors walked down the offsite power sources (startup transformers) and continued to monitor communications with the emergency facilities. The inspectors examined the auxiliary and startup transformers for damage. PG&E personnel reported that two switches were damaged in the 230 kV system at the offsite Morro Bay switchyard. The Morro Bay switchyard is one source of offsite power to the startup transformers. PG&E declared the startup transformers inoperable to provide safe electrical isolation and cleared the 230 kV lines to support replacement of the damaged switches. The startup transformers were returned to operable status within the 72-hour limiting condition for operation action statement. The Ris remained at the site, continuing to inspect and monitor PG&E actions until 2 p.m. PST on December 23. PG&E exited the NOUE at approximately 12:15 p.m., PST on December 23, 2003.

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

a. Findings During the inspections, no system or structural damage or evidence of differential deflections were detected, and no site ground effects were noted during exterior visual inspections. In addition, no damage was noted to the administration building, which is designed to the Uniform Building Code. The licensee's immediate response to the earthquake was effective in ensuring continued safe operation, and their implementation of the NRC's prompt notification requirements was timely and correct.

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

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

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

The inspectors reviewed PG&E's reportability procedure for loss of the early warning system sirens. During the review, the inspectors noted that the procedure for notification of the NRC for a loss of the early warning system sirens only addressed sirens within a 10-mile radius and not the entire Diablo Canyon Emergency Planning Zone, as defined in the Emergency Plan. In this case, the licensee did inform the NRC of the loss at the time the 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 would be ramped down to approximately 25 percent power to prevent the traveling screens, from being clogged with kelp, which could necessitate tripping the circulating water pumps and a reactor trip of the affected unit. At 1:30 a.m., on December 10, operators slowly decreased power on both units. The inspectors responded to the site and monitored the operator performance during the downpower and operator response to any high differential pressure across the traveling screens.

b. Findings No findings of significance were identified.

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 or changes to accident analyses required additional operator action beyond that credited in the design basis to compensate for these conditions. PG&E tracked two types of these conditions: operator burdens and operator workarounds.

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

Enclosure

ucf z Enclosure 4 0 iUNITED STATES NUCLEAR REGULATORY COMMISSION REGION IV 611 RYAN PLAZA DRIVE, SUITE X

400 ARLINGTON, TEXAS 76011-4005 January 16, 2004 Gregory M. Rueger, Senior Vice President, Generation and Chief Nuclear Officer Pacific Gas and Electric Company Diablo Canyon Power Plant P.O. Box 3 Avila Beach, CA 93424

SUBJECT:

DIABLO CANYON POWER PLANT - PRELIMINARY RESULT OF NRC EVENT FOLLOWUP 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 been conducting event followup inspections at the Diablo Canyon Nuclear Plant in direct response to the December 22, 2003, San Simeon earthquake. The purpose of this letter to you the preliminary results of these inspection activities and to describe is to communicate the NRC's planned and future actions with respect to further followup, actions, and documentation associated with the 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 inspection results in the areas reviewed. Please note that the final inspection preliminary results and findings are not being issued at this time, are subject to further review, and will be documented in NRC Inspection Reports 05000275;323/2003008 and 05000275;323/2004002 to be issued approximately 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 which involve the site resident inspectors and Regional and Office of Nuclear Reactor Regulation (NRR) representatives. The NRR representatives were seismic provided technical experience to the inspection activities. The first phase, experts that which has been completed, involved the immediate response to the December 22, 2003, earthquake inspectors. Immediately following the earthquake, both resident inspectors, by NRC who were onsite at

I--.

11-1 Pacific Gas and Electric Company the time of the earthquake, reported to the control room and walked down control board panels to ascertain the status of safety systems and verify that your staff had implemented their emergency plan. The inspectors also performed independent visual examinations of selected structures, systems, and components. During these walkdowns, the inspectors did not identify any broken, shifted, or leaking pipes; damaged support braces; displaced equipment; or cracks or spalling in concrete walls and floor or the plant's foundation that would indicate any signs of damage.

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 seismic acceleration, 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 were prioritized based on their risk significance. During this Phase 2 portion of the inspection, the NRC staff concluded that, in order to assure that there was no damage to equipment inside the containment buildings, it would be necessary to perform a visual examination of selected structures, 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 differential deflections were detected. The NR5C staff concluded that, based on there being no damage and the near identical designs of both units' containment buildings, an inspection of the Unit 1 containment building could be deferred until the Unit 1 refueling outage scheduled to begin in March 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 2004 refueling 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 your January 5, 2004, Special Report in San Luis Obispo, California. This meeting will be open to public observation and will provide attending members of the public a period for comments and questions prior to the conclusion of the meeting. Immediately following the technical meeting orn the Special Report, a second" Category 1 public meetingg will be conducted to. provided your staff a more detailed interim exit for the Phase 1 and~d 2 inspection activities and a review of ongoing and planned inspection activities.

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

Pacific Gas and Electric Company Room or from the Publicly Available Records (PARS) component of NRC's document system (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 William B. Jones, Chief Project Branch E Division of Reactor Projects Dockets: 50-275 50-323 Licenses: DPR-80 DPR-82

Enclosure:

Diablo Canyon Response to San Simeon Earthquake on December 22, 2003 cc w/enclosure:

David H. Oatley, Vice President and General Manager Diablo Canyon Power Plant P.O. Box 56 Avila Beach, CA 93424 Lawrence F. Womack, Vice President, Power Generation & Nuclear Services Diablo Canyon Power Plant P.O. Box 56 Avila Beach, CA 93424 James R. Becker, Vice President Diablo Canyon Operations and Station Director, Pacific Gas and Electric Company Diablo Canyon Power Plant P.O. Box 3 Aviila Beach, CA 93424 Sierra Club California 2650 Maple Avenue Morro Bay, CA 93442

Pacific Gas and Electric Company Nancy Culver San Luis Obispo Mothers for Peace P.O. Box 164 Pismo Beach, CA 93448 Chairman San Luis Obispo County Board of Supervisors Room 370 County Government Center San Luis Obispo, CA 93408 Truman Burns\Robert Kinosian California Public Utilities Commission 505 Vani Ness Ave., Rm. 4102 San Francisco, CA 94102-3298 Diablo Canyon Independent Safety Committee Robert R. Wellington, Esq.

Legal Counsel 857 Cass Street, Suite D Monterey, CA 93940 Ed Bailey, Radiation Control Program Director Radiologic Health Branch State Department of Health Services P.O. Box 942732 (MS 178)

Sacramento, CA 94234-7320 Richard F. Locke, Esq.

Pacific Gas and Electric Company P.O. Box 7442 San Francisco, CA 94120 City Editor The Tribune 3825 South Higuera Street P.O. Box 112 Sang Luis Obispo, CA 93406-01'12 Ja:mes D. Boyd, Commissionefr California Energy Commission.

1516. Ninth Street (MS 34)

Sacramento, CA 95814

Pacific Gas and Electric Company Chief, Technological Services Branch FEMA Region IX 1111 Broadway, Suite 1200 Oakland, CA 94607-4052

Enclosure Preliminary NRC Inspection Results to Date for Diablo Canyon Response 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, a

6.5 magnitude earthquake occurred 50 km NNW of Diablo Canyon Power Plant at a depth of about 7 kilometers near San Simeon, California. The earthquake was measured as 0.04g acceleration 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 ground accelerations for Diablo Canyon are 0.2g and 0.4g, respectively. The reactor trip system has a reactor trip setpoint nominal value of 0.35g acceleration. The reactor trip was set at 0.3g at the time of the San Simeon earthquake. Therefore, the measured acceleration was less than 15 percent of the reactor trip setpoint and well within the bounds of the seismic analyses.

The station is also evaluated for its capacity to withstand ground acceleration resulting from a 7.5 magnitude earthquake originating in the offshore Hosgri fault.

Units 1 and 2 remained at full power throughout the event. Both NRC resident inspectors were onsite at the time of the earthquake, responded to the control room to observe immediate operator actions, and maintained an NRC presence onsite for the next 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . Immediately following the first shock, the resident inspectors established a direct open telephone link between 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 of the two inspectors and information concerning the station's status was continuously provided to NRC staff.

Fifty-six of 131 early warning system sirens lost power as a result of the earthquake. Alternate means of notifying people within the affected areas were available. The evacuation routes remained 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 sirens were without power. These remaining 4 were restored in the subsequent 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

B. Inspection of Structures, Systems, and Components

Purpose:

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

Preliminary Inspection Results to Date:

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

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

During the period of January 5-9, 2004, further inspections were performed by the resident inspectors and an NRC senior reactor inspector. During this inspection activity, all levels of the turbine, auxiliary, fuel handling, saltwater intake, and containment buildings were visually inspected, with particular attention given to systems and components having the most risk significance. During the inspections, no system or structural damage or evidence of differential deflections were detected, and no site ground effects were noted during exterior visual inspections. In addition, no damage was noted to the administration building, which is designed to Uniform Building Code.

C. Inspection of Licensee Event Response

Purpose:

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

Preliminary Inspection Results to Date:

The licensee's immediate response to the earthquake was effective in ensuring continued safe operation. The licensee's subsequent inspections were effective in evaluating whether any structural damage occurred.

The licensee convened an Event Response Team to capture lessons learned and to fully understand the response of the plant systems. The NRC inspectors reviewed the team's findings and concluded that the scope and depth of the team's reviews were comprehensive and; effective. The review of control room annunciator alarms identified enhancements needed to 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 and correct.

All seismic instrumentation functioned correctly. The NRC inspectors conducted a review of the required surveillances on seismic monitoring instruments. AM ifnstruments were correctly calibrated. The inspectors noted that the licensee is in the process of upgrading the current Earthquake 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~ew M. e ,,n ["n pe-n of th ic

Purpose:

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

Preliminary Inspection Results to Date:

Casualty Procedure M-4 was used in responding to the earthquake.

Although overall response to the earthquake was adequate, several lessons were learned by the licensee from a subsequent review of the implementation of the procedure. The licensee has begun a general revision to improve its quality based on this experience. The NRC plans to review this procedure following its revision.

The inspectors also performed a review of the licensee's Special Report 03-04, dated January 5, 2004. This Special Report is required by the facility operating license (i.e., the license requires the licensee to evaluate each seismic event where onsite monitoring instruments are actuated to determine the magnitude of the ground motion and resultant effect upon facility features important to safety). The inspectors noted that this report was prepared based solely on the seismic monitoring instrument located on top of the containment basemat without consideration of other seismic monitoring instruments at the station. As a result of this observation, the licensee issued a corrective action document to submit a supplemental report to the NRC that will describe the analysis of data from all actuated seismic monitoring instruments (acceleration, displacement, and frequency spectrum) and will compare these to design values at the corresponding location in the plant. The NRC will review this supplemental report upon receipt from the licensee.

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

Lnclosure 5 December 22,2003 San Simeon Earthquake PRELIMINARY REPORT ON DECEMBER 22, 2003 SAN SIMEON EARTHQUAKE By Rakesh 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 at 11:15:56 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 were killed and about 40 buildings collapsed or severely damaged at Paso Robles which is located about 39 km (24 mile) from the epicenter. At least 40 people were reported to be injured in the Paso Robles-Templeton area. This preliminary report presents basic information on the epicenter location, intensity of shaking, and performance of buildings in the Central Coast region of the California.

Epicenter Location and Shaking Intensity The Central Coast of California has several active faults (Figure 2). Although exact location of the earthquake of December 22, 2003 is still being determined, this earthquake occurred somewhere on the northern end of the San Simeon/Oceanic/HosGri Fault System. Early analysis 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 in 1952 with a magnitude of 6.2.

34o1~4 122 , 121E0 129 Figure 1. Location of the December 22, 2003 San Figure 2. Faults in Central Coast of California Simeon earthquake (USGS). (Adapted from a USGS map).

(ioei Preliminary Report Goel I Preliminary Report

December 22, 2003 San Simeon Earthquake PasoRobles I.

tA-aademin

.onBay San LuisObispo an Luis 0bispo 6 Figure 3. Reverse fault mechanism'. Figure 4. Map of San Luis Obispo County 2 .

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

CISN Rapid Instrumerital Intensity Map Epicenter: 11 km NE d San Simeon. CA Mo-DN.22.200311:1"s6AMPSTMA6. N03.71 W121.0 Depth:76kaIQ.40148755 CISN Peak Accal. Map (in%g) Epicenter: 1i kn NE of San Simeon CA M-O.o22.200311:10.56A0PST MISS N35.71W121.0 D.PtIh7634 I040148755

.122s >a l12 -1201

122' 2'A0

03partaln ..55 U.,r-#

asa144 192t@9259 193 3405Z 6412 .544 10t4004..4 .0.1 011.l11144 344 i14 [-S 3 645 164 .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 of the rupture). The hospital recorded about 50%g horizontal motion and 30%g vertical motion at the ground level 3 . Templeton is about 10 km (6 mile) south of Paso Robles, where significant damage occurred during the earthquake (see Figure 4 for city locations). Therefore, it is likely atAdapted from httn:/Iwww3ulakron. edu/seotzraphv/Irb/phvsf97/Iectures/platetect/sIdO3 htrn 2 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-FrLVH1lll )ir DeUport

December 22, 2003 San Simeon Earthquake that Paso Robles experienced horizontal accelerations in excess of 50%g. The station closest to the epicenter was near Cambria, 12 km (8 mile) from the epicenter, near a Caltrans bridge on Hwy 1. Though the station is much closer, it only recorded 18%g. This early data indicates apparent strong directivity in the direction of the rupture propagation toward Templeton. Another record was recovered from the San Luis Obispo, about 61 km (38 mile) to the south of the epicenter, where 17%g was recorded at a USGS station downtown. A contour map of the peak horizontal 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 the most 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). Summarized first is the overall observations on the damage pattern in the downtown area followed by more detailed description for selected buildings.

M -

13t Street C W120.68805 A

N a 12thSre N35.ff2675 1NS5.92613 (I) W120.63931 W120.68775 Cyr N35.62642.W120.68t98 N35.62553,W120.69030i City Park C-egi. Librry Pas RoblesInn N35.62471.W120.69011 PasoRoblesCity Hall Paso Robles Downtown: Damaged Area Layout Blocks with Major Damage are Shaded (Sketch by Rakesh K. Goal, Not to Scale)

Figure 7. Damaged area in downtown Paso Robles.

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

uoei J1 Preliminary Report tGoel Preliminary Report

December 22, 2003 San Simeon Earthquake Most buildings in the downtown Paso Robles business district area are very old, some more than a century ago, constructed of unreinforced masonry. Unreinforced masonry construction is known to be especially vulnerable to earthquakes and it is not surprising that such buildings suffered extensive damage during the San Simeon earthquake. Most of these buildings were not designed for seismic loads and lacked proper seismic detailing. A few had been upgraded by tying the floor diaphragm to the walls. The damage level was much higher in buildings that were not retrofitted compared to those that had been retrofitted. None of the buildings with some kind of seismic retrofit scheme implemented collapsed indicating that even basic 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 largest damage were all located on street corners (see Figure 7). Configuration of these corner buildings with windows on the street sides and solid opening-less walls on the two other sides created extreme plan asymmetry, i.e., large eccentricity between floor center of mass and center of rigidity. The resulting torsional motions during the earthquake shaking imposed much larger demands on these buildings, compared to buildings with symmetric plans, leading to much larger damage.

Unreinforced masonry buildings even without seismic retrofit located mid-block did not suffer catastrophic failure that occurred in the Acorn building. Most buildings in the affected area, especially on the Park and 12th Streets, are constructed without any gap between them. It seems that the adjacent buildings provided confinement to each other, except to those on the corner, 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 observation is consistent with the observation in the previous earthquakes that the shaking may be strong in the 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 Paso Robles. A two story unreinforced masonry building constructed more than a century ago, it housed a Clock Tower on the corner of 12th and Park Streets and several small businesses on the ground floor on 12 th Street and Park Street sides. This building collapsed resulting in the only two fatalities during the San Simeon earthquake (Figure 8).

The lateral load carrying system of this two-story building appears to be unreinforced masonry 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, the clock tower on the Park and 12th street corner of this building collapsed. Furthermore, the second story wall on the Park Street side appeared to have collapsed out-of-plane. As a result, the roof slid to the Park street side leaving a big gap in what appears to be collapsed roof of the second half of the building on the 1 2th 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 strong shaking was in the east-west direction. The wall on the west side (on the Park Street side) of the building collapsed out-of-plane due to much smaller resistance.

Goel 4 r-AI--. DANA_+

rreCl11m1mary report

December 22,2003 San Simeon Earthquake

. I ~..:

Figure 8. Collapsed Acorn building on the corner of 1 2th and Park Streets in downtown Paso Robles (Picture by 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 story and some windows in the second story (Figure 9). The other two sides, which face away from the streets, have only a few window openings in the second story and solid wall in the first story without openings. This configuration led to significant eccentricity between the center of mass and center of rigidity. The damage pattern described next for this building is consistent with that expected 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 of rigidity - of the building (Figure 10). Apparently, this corner experienced large drifts due to torsion of the building during the earthquake. Significant diagonal shear cracks appeared in the first story wall on the east as well as the south sides; both these sides of the building face the streets (Figure 11). This appears to be consistent with the expected large drifts in this wall of the first story. Much less cracking is visible in the second story wall (Figure 12). Drifts are expected to be much smaller in this wall of the second story because of much fewer openings compared to the first story. No cracks were visible in the north and west walls of the building.

Ali's PersianRugs Building This two story building located on the south-west corner of Park and 13th Streets suffered extensive loss of its cladding. The brick facade peeled off from near the roof level from faces on both the Park and 13th Street. It appears that the brick facade was attached to the wall with cement mortar. No ties were noticeable on the open face of the building or the rubble below. The other external structural damage appears to be minimal in this building.

NI P i r e Goel Preliminary Report

December 22,2003 San Simeon Earthquake Figure 9. Marlow Interior building located at the Figure 10. Large cracks at the corner of the Marlow corner 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 the Marlow 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 suffered minor structural damage (Figure 14). A few bricks separated and fell from the decorative parapet. 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 retrofit scheme appears to have prevented major damage to this building.

Lxoel Preliminary Report (Joel 6 Preliminary Report

December 22, 2003 San Simeon Earthquake Figure 13. Peeling of the brick facade in the second Figure 14. Minor peeling of bricks from the story of the Ali's Persian Rug building on the corner decorative parapet of the Bistro Laurent building on of 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 Wireless Figure 16. A close-up view of the seismic retrofit anchors in building on the corner of Pine and 13 th the Cingular Wireless building (Picture by Rakesh Goel).

Streets in downtown Paso Robles (Picture by Sam Vigil).

Cingular Wireless Building Located on the corner of Pine and 13th Streets, this one-story masonry building suffered minor structural damage (Figure 15). The brick fagade on the south-west corner of the building separated and fell. This masonry building also 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 (Figure 16).

As noted previously for the Bistro Laurent building, this basic retrofit scheme appears to have prevented major damage to this building.

(Joel CGoel 7 7

Preliminary Report Preliminary Report

December 22,2003 San Simeon Earthquake 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 frame supporting the brick facade. Very little damage was noticeable in the observation tower (Figure 17). The attached restaurant suffered moderate nonstructural damage: a few clay roof tiles came loose 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 restaurant on Spring Street in Paso Robles (Picture by Rakesh of the Paso Robles Inn (Picture by Rakesh Goel).

Goel).

Psigure 1. Inwo-story guest quarter Di Figure 20. Cracks in the brick walls of the guest Paso Robles Inn (Picture by Sam Vigil). quarter building at the Paso Robles Inn (Picture by Rakesh Goel).

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

88 Preliminary Report Goel PreliminaryReport

December 22, 2003 San Simeon Earthquake Performance of Atascadero City Hall Built in 1918, the Atascadero City Hall (Figure 21) is located about 63 km (39 mile) from the epicenter. Discussion with the city engineer indicated that the structure consists of reinforced concrete space frame with brick fagade. The exterior damage primarily consisted of cracks and severe spalling of the brick fagade on the rotunda (Figure 22). Falling bricks from the fagade took out a sky-light and fell on the tables of a room located at the rotunda office level. No one was injured because this room was unoccupied at the time of the earthquake. The reinforced concrete space frame supporting the dome roof was found to have suffered no damage.

Figure Li. Atascadero CAty Hall (Picture by Kakesh Figure 22. Feeling of brick facade from the rotunda Goel). of 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 city council 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 spilled their contents during the earthquake (Figure 25). Contents of the display cases in the lobby were tossed around during the earthquake. Several glass display pieces fell to the ground and broke (Figure 26).

Figure 21. Atascadero City Hall rigure LL. reeling o1 brick fapade from the rotunda Goel). of the Atascadero City Hall (Picture by Rakesh Goel).

(ioel9 Prlimiary epor Uoel 9 Preliminary Report

December 22, 2003 San Simeon Earthquake figure 23. Iypical cracks in the walls of Atascadero s ~s;^.r,- Xig of plaster from ring beam of the Wl-l City Hall (Picture by Rakesh Goel). rotunda of the Atascadero City Hall (Picture by Rakesh Goel).

Figure 25. Damage in the kitchen of Atascadero City Figure 24. Damage in the lobby of the Atascadero Hall (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 masonry buildings, very little structural damage was observed in the city. The lack of damage in San Luis Obispo 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 ground accelerations in the city - the peak horizontal ground acceleration recorded during the earthquake was about 17%g at a USGS recording station.

Ah Louis Store (Figure 25), a two-story unreinforced masonry building located on the corner of Palm and Chorro Streets, is designated as a historic landmark in the city. No noticeable change in cracks on the south-west wall, which has been retrofitted, was observed after the earthquake (Figure 26). However, new cracks appeared on the north-east wall of the building (ioel 10 Preliminary Report GJoel 10 Preliminary Report

December 22, 2003 San Simeon Earthquake (Figure 27). The building was temporarily closed for inspection and subsequently cleared for occupancy.

Several vulnerable buildings in San Luis Obispo are located on the campus of the Mission San Luis Obispo de Tolosa. This adobe structure survived the earthquake without damage. The only noticeable damage was widening of existing hair-line cracks at the junction of the Bell-Tower building and the adjacent building (Figure 28). The mission was open for business in the afternoon of December 22, 2003.

Figure 25. Ah Louis Store in downtown r igure Ao. CracKs existing prior to the eartnquaKe anu Obispo (Picture by Rakesh Goel). attempt to retrofit on the south-west wall of the Ah Louis 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 bell Louis 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 of various 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; one of the vertical rod supporting the light fixture pulled out from the roof due to insufficient thread length (Figure 29).

Goel 11 11I Preliminary Report Preliminary Report

December 22, 2003 San Simeon Earthquake Figure 29. Damage to a light fixture in Recreational building on the Campus of California Polytechnic State University, San Luis Obispo (Picture by Rakesh Goel).

Goel 12 Preliminary Report Goel 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 Commission ATTN: Document Control Desk Washington, DC 20555-0001 Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Units 1 and 2 Special 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 percent power, ground motion was felt and recognized as an earthquake by a consensus of control room operators. The earthquake force monitor recorded greater than 0.01 g for the seismic event. Therefore, operations personnel declared an Unusual Event, in accordance with emergency action level (EAL) NUEI8. (Reference NRC Event Notification Number 40258.) At 0330 PDT, the Unusual Event was terminated upon confirmation 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 a seismic event: For seismic monitoring instruments actuated dunng a seismic event, "data shall be retrieved from actuated instruments and analyzed to determine the magnitude of the vibratory ground motion. A special report shall be prepared and submitted to the Commission ... describing the magnitude, frequency spectrum, and resultant effect upon facility fbatures important to safety."

Enclosure I describes the ground motion analysis including the magnitude and frequency spectrum of this event. Enclosure 2 provides an analysis of the resultant effect 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 to public 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 at 415-973-2791.

A member of the STARS (5trategic Teamins and Rewource Sharing) Altiance Callaway - Comanche Peak - Diablo Canyo

Palo Verae - Soth Texas Project* WoLf Creek

0UHL try; UrnlLeU OLdLeS NUL.Ied' tlegUldLOr'; uD DUD e - zi-uec - uj t::iPa ut{IM; Page 3 Document Control Desk PG&E Letter DCL-03-141 October 31, 2003 Page 2 Sincerely, Lawrence F. Womack SWH/A0593059 Enclosures cc: Bruce S. Mallett, Region IV David L. Proulx, Resident Girija S. Shukla, NRR Diablo Distribution

Sent By: United States Nuclear Regulator; 805 595 2355; DeC-29-03 7:07PM; Page 4 Enclosure I PG&E Letter DCL-03-141 Diablo Canyon Power Plant Deer Canyon Earthquakes of October 18, 2003 On October 18, 2003 at 0027 and 0039 PDT, two small local magnitude (ML) 3.4 earthquakes occurred. The events are located approximately 5 km east of Diablo Canyon Power Plant (DCPP), in the region northwest of Deer Canyon.

Both earthquakes were felt in the DCPP control room; the second event triggered strong motion instruments at the plant site. The earthquakes are part of a sequence of 14 small earthquakes that occurred between October 12 and October 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 Seismic Program. The CCSN data are augmented by recordings from the U.S.

Geological Survey's (USGS) Northern California Seismic Network (NCSN). The CCSN consists of 20 seismographic stations, including five dual-gain 3-component stations (large triangles in inset to Figure 1). The addition of the CCSN, including the three-component stations greatly improves the accuracy of the earthquake locations in the region around DCPP.

Figure 1 shows the Deer Canyon sequence with previous earthquakes for the period 1987 to the present. The October 2003 sequence consists of 14 earthquakes with magnitudes ranging from 0.4 to 3.4. The previous seismicity shows scattered activity across the San Luis/Pismo block; the Deer Canyon earthquakes 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 operators reported that the second event was the stronger. The first event did not trigger the seismic instruments. The second event did not trigger the Basic Seismic System analog recorder (Kinemetrics SMA) in the control room, however the Kinemetrics digital recorders (SSA) at the Unit 1 containment base, top of containment, the auxiliary building, and the free-field pit location (near the fitness trailer) did trigger on the second event. According to David Castleman of Kinemetrics, Inc., the SMA system worked properly; however, the system did not trigger because the containment base ground motions contained significant energy outside the 1.0 to 10.0 Hz bandwidth of the SMA trigger. The Supplemental System was inoperable at the time of the earthquakes; however, three temporary accelerometers (TerraTech GSR-1 8), located in the Auxiliary and the Turbine buildings, recorded the second event.

1

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uf/ M; Hage 5 Enclosure 1 PG&E Letter DCL-03-141 The earthquake force monitor (EFM) located in the control room measured 0.02g on the vertical component. The EFM measurement is from the sensor at the Unit 1 Containment base and does not have the baseline drift removed. With the baseline drift removed, the peak acceleration on the vertical component is 0.011g.

Table 2 lists the peak accelerations, peak velocities, and peak displacements of the free-field and Unit I containment base ground motions after the filtering and baseline corrections are applied. The peak accelerations range between about 1 to 2 percent g with the largest peak acceleration on the vertical component.

Regarding frequency spectrum, the response spectra were computed for the free-field and Unit 1 containment base recordings. The 5% damped spectra for the free-field and Unit 1 containment base recordings are shown in Figure 2 and 3, respectively. The response spectra for this earthquake show very high frequency content that is typical for an earthquake of this magnitude. For the free-field, the horizontal spectra peak at about 12 Hz and the vertical spectrum peaks at about 20 Hz. For the Unit 1 containment base, the peaks are shifted to slightly smaller frequencies. This shift to lower frequencies is an expected effect of the large foundation.

Conclusions The occurrence, location, and magnitude of the October 18, 2003 Deer Canyon earthquakes is not a surprise as the sequence of earthquakes is consistent with our understanding of the tectonic framework in the region around DCPP. The events occurred in the San Luis/Pismo block, which is a region of previous seismicity. Additional small earthquakes are expected to occur within this block.

The ground motions from the second event (0039 PDT) are typical for ground motions from a magnitude 3.4 earthquake at a distance of 5-0 km.

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

2

Sent By: United States Nuclear Regulator; 805 595 2355; Dec-29-03 7:07PM; Page 6 Enclosure 1 PG&E Letter DCL-03-141

-12 1'oO -120'45' -120 30 36^

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t6 10 I Distance (kN Figure 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) from October 1987 to October 11, 2003. The data were recorded by the PG&E Central Coast Seismic network (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 stations also are shown on larger map(green triangles). Location of seismic cross section AA' is shown on map 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 Isthe boundary of the San Luis/Pismo structural block (Lettis and others, 2001).

3

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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 Enclosure 1 PG&E Letter DCL-03-141 II IN nR uu

]-- I I . 11111 I.

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Figure 3. Response spectra at 5% damping for the unit I containment base ground motion.

5

n:

CD

'-I Enclosure 1 PG&E Letter DCL-03-141 October 12 to 24, 2003.

Table 1: Earthquake location parameters for the Door Canyon sequence, Felt events are highlighted in gray.

2 C

01st. tO Ct O.P. & G;8p bHWo neOSt orIz. Vemt. No. P- Ct S-Wave etas. Statlon RIMS No. Sowave Error Error wave flrSt a

Lon Lime Depth radings (deg) (km) (seC) MD readingS (k) {km) motions No. Date (UTC} La1 (C 145 3 0.13 2.3 2 0.41 0.39 43 1 10112/200313:32 28.54 35 11.97 -12048.83 6.6 52 (C 137 3 0.07 0.5 1 0.66 0.33 5 C 2 10/12/200316:5737.60 3512.28 -12047.59 3.8 6 34 123 3 0.14 1.7 4 0.37 0.17 30 3 10h17l2003131914.33 3512.49 12047.88.3.6 0 Waz ~Z4,8 3 0 .A.. ~ ~ '~9 ltI C 4 a

-120 47.81 3.7 6 149 4 0.05 0.4 I I V J U 6 10M81200307:40 49.52 35 12.10 (I 147 4 D.09 1.1 1 0.85 0.44 8 C 7 10/18/20307:41 43:44 35 12.18 -120 47.92 3.7 9 3.7 16 132 4 0.12 1.3 3 0.52 0.21 11 8 10W18/200307:55 18.96 35 12.13 -120 47.88 7 N 9 146 4 0.07 1.1 1 0.61 0.31 U 9 10J202O3 10:38 21.93 35 12.24 -120 47.97 3.6 8 9 142 3 0.07 0.9 1 0.67 0.33 10 10l20120O318:22 37.72 35 12.35 -12048.05 3.8 46 50 4 0.10 1.5 3 0.43 0.61 15 11 10/201319:28 31.85 3515.05 -12044.37 8.9 t25 3 0.11 1.2 2 0.54 0.25 12 12 10/211200308:3540.18 3512A3 -120 48.00 3.6 24 119 3 0.12 2.6 3 0.36 0.17 41 13 10121/200t313:43 36.44 35 12.65 -120 48.20 3.7 37 6 6 147 4 0.07 0.7 0 0.52 0.33 14 10124/200323:30 52.84 35 12.06 -120 47.73 3.4 6

MD = duratcon magN~tue

Sent By: United States Nuclear Regulator; 805 595 2355; Dec-29-03 7:09PM; page lO/11 Enclosure 1 PG&E Letter DCL-03-141 Table 2. Peak ground motions values from the Basic Seismic System digital recorders (after filtering and baseline correction)

Peak Peak Peak Peak Instrument Instrument Component Peak Peak location Acceleration Velocity Displacement type (a) 3 (emls) (cm)00A

..... .. u . .. 0.0 I

Horizontal 1 I n rwen 0.0100 Kinemetrics Free field pit V.U'rw 0.32 SSA (near fitness (Channel 1) 0.0042 0.022 4-0.19 0.19 4 - --

0.0042 trailer) Vertical (Channel 2) _ _

. 0.1 _ _A A o_

Horizontal 2 0,011 0-.19 UM§OU 4.. ._

(Channel3) _.0A77 Unit 1 Horizontal I 0.008 0.16 0.0077 Kinemetrics SSA Containment (Channel 11- I _ - I - - 0.0080 base, Verticol 0.012 0.16 0.0060 89' elev. (Channel 2) -A 0.009 4 022 Horizontal 2 0.009s 0.22 0.00N4 If-h..nd. 'QN I_ _ _ _ _ _ I I.I -

7

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,uc-LbdLi nfYULdLUU1O OUD DtId bient by: unileO .>alLeS Enclosure 2 PG&E Letter DCL-03-141 Features Important To Safety For Analysis of The Resultant Effect Upon Facility The Seismic Event of October 18, 2003 Plant Systems Response:

a walkdown of the facility was Per Casualty Procedure (CP) M-4, "Earthquake," normally. No visible damage was conducted. All systems continued to operate control room for the first seismic event; discovered. No alarms were received in the seismic event are as follows:

alarms received in the control room for the second U-i Alarms level was high in the normal Accumulator 1-3 level high; the accumulator times, and operating band (71472%). The alarm came in and out several returned to normal. 5 came into alarm and returned Turbine supervisory instrument drawer. Bearing to normal.

U-2 Alarms 5 came into alarm and returned Turbine supervisory instrument drawer. Bearing to normal.

Seismic Monitoring Instrumentation Response:

this date. The first event was felt at Two seismic events were felt on the plant site 0039. CP M4 was entered after the second approximately 0027 with the second one at any increase on the seismic monitors.

event. The first event was felt but did not show on the vertical indication of earthquake The second event showed approximately 0.02g monitor indicator, EFM-1. During the seismic event, the Unit 1 containment base force about 0,02g, based on initial indications, appeared to have experienced ground motion room alarm did not actuate. The however the Kinemetrics trigger for the control trigger is 0.01 g, +/- 0.002g; the maximum nominal trigger setpoint for the Kinemetrics to be 0.011g.

acceleration, after analysis was determined performed by the instrument vendor The Kinemetrics trigger instrument calibration tested; the as found data was within was following this event. The Kinemetric triggertrigger switch was found to be within ifs specification. In addition, the Kinemetrics designed for this low level event.

instrument tolerance and thus operated as and trigger were proper for this low Therefore the response the Kinemetrics system on vendor-provided calibration data level event, and were considered operable based and resulting engineering evaluation.

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

South Texas Project . Wof Creel

Palo Verde Caltaway

Comenche Peak . Diablo Canyon

Pacific Gas and Enclosure 7 Electric Company Lawrence F.Womack Diablo Canyon Power Plant Vice President P.Bx5 Nuclear Services Avila Beach, CA934Z4 805.545.4600 Fax: 805.545.4234 January 5, 2004 PG&E Letter No. DCL-03-184 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Units 1 and 2 Special 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 percent power, a 6.5 magnitude earthquake occurre 1 2 operating)at 100 Simeon, California. Ground motion was felt and recogni km northeast of San an earthquake by the control room operators. The earthquake force monitor recorded greater than 0.01g for the seismic event. Operations personnel declared an 1122 PST. (Reference NRC Event Notification Number40408.) Unusual Event at 2003, at 1212 PST, the Unusual Event was terminated On December23, upon confirmation 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 a seismic event: for seismic monitoring instruments actuated during "data shall be retrieved from actuated instruments and analyzed a seismic event, to determine the magnitude of the vibratory ground motion. A special report shall be prepared and submitted to the Commission ... describing the magnitude, frequency resultant effect upon facility features important to safety." spectrum, and describes the ground motion analysis including the magnitude and frequency spectrum of this event. Enclosure 2 provides an analysis of the resultant effect upon facility features important to safety.

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

If you have any questions, please contact me at 805-545-4600 or Mr. Lloyd Cluff at 415-973-2791.

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

Comanche Peak

Diablo Canyon

Palo Verde

South Texas Project - Wolf Creek

Document Control Desk PG&E Letter DCL-03-18 4 j January 5, 2004 7 Page 2 Sincerely, Z.:Z K Z-,

Lawrence F. Womack SWH/A0597032 Enclosures cc: Bruce S. Mallett, Region IV David L. Proulx, Resident Girija S. Shukla, NRR Diablo Distribution

Enclosure 1 PG&E Letter DCL-03-182 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 Simeon Earthquake, 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. The San 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 local magnitude (ML) 6.2, approximately 8 km north of the 2003 epicenter. The San Simeon Earthquake was widely felt from Los Angeles to San Francisco. Earthquake ground effects included landslides and related ground failure near the epicenter, however no surface faulting was observed. Most of the damage occurred in Paso Robles, 39 km ENE 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 the Control 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 vigorous aftershock sequence that extends about 30 km southeast of the main shock. As of December 26, 2003, approximately 960 aftershocks have occurred, including about 120 magnitude (M) 3 events and 19 M 4 earthquakes. During the first 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months , the activity was about 50 percent higher than the average for a California sequence according to the US Geological Services online report, December 24, 2003, (httP://www.uss.Qov/).

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

Figure 1 shows the location of the main shock and first 20 hours2.314815e-4 days 0.00556 hours 3.306878e-5 weeks 7.61e-6 months of aftershocks. There is concentrated activity near the main shock and at the southeast end of the aftershock zone. Most of the aftershocks near the main shock are located between the Oceanic and Nacimiento fault zones, whereas the earthquakes to the southeast are not as constrained by the faults. It is not clear which fault, if either, was the cause of the earthquake. The aftershock patterns in depth view (Figure 1, cross sections A' and BB') show diffuse activity above the main shock and no obvious fault plane. The closest 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 basic seismic system analog recorder (Kinemetrics SMA) in the Control Room and the Kinemetrics 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). The supplemental system was out of service at the time of the earthquake, however, three temporary accelerometers located in the Auxiliary and Turbine Buildings and a 1

Enclosure 1 PG&E Letter DCL-03-18 2 permanent instrument in the basement of the 500 kV Switching Center triggered. The supplemental system is currently inoperable and replacement parts are obsolete; both the basic and supplemental systems are scheduled to be replaced in January 2004 with new instrumentation.

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

Regarding the frequency spectrum, the response spectra were computed for the free-field and Unit 1 containment base recordings. The 5 percent damped spectra for the 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 shape for 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 6.5 reverse earthquake recorded at 38 km distance. Current attenuation relations for rock site yield median horizontal spectral accelerations that are 1.5 to 2 times larger than the recorded free-field spectra. For the Unit 1 containment base, the spectra peak at 3 to 4 Hz for all three components. The containment base spectra show amplification in this 3 to 4 Hz range as compared to the free-field spectra. At short frequencies (< 2 Hz), the spectra from the containment base are similar to the free-field spectra. At high frequencies (e.g. 10 Hz), the horizontal spectra from the containment base are smaller than the free-field spectra.

Conclusions The San Simeon Earthquake is the largest measured in the San Simeon region. The reverse fault motion of the main shock and aftershocks and the aftershock patterns are consistent with previous seismic activity in this region. The free-field ground motions recorded at DCPP are below then median ground motion estimated for this event using current attenuation relations for rock sites.

Dr. Norman Abrahamson and Ms. Marcia McLaren of PG&E Geosciences Department are preparing a detailed report of the San Simeon earthquake. The report will include analyses of the Kinemetrics SMA tape system. The detailed report will be available upon request 2

Enclosure 1 PG&E Letter DCL-03-182 Reference (1) McLaren, M. K. and Savage, W. U. (2000). Seismicity of South-Central Coastal California: October 1987 through January 1997, Bull Seism. Soc. Am. 91, no. 6, pp.

1629-1658.

3

Enclosure 1 PG&E Letter DCL-03-182

-121.5 -121.25 -121 -120:75 -120.5 36 -

\

35.75 -

35.5 -

MAGNITUDES

\

0.0+

35.25- 1.0+

o 2.0+

O 3.0+

4.0+

3 5.0+

6.0+

C' 3.0+

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C 0 10-00 a is - 0 -

20- 25-4 25, 0 5 10 I5 20 25 20 35 40 45 0 5 10 IS 20 25 J0 3S 40 4S S0 Distance(km) 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;; circles are events that have been reviewed by USGS seismologists NCEDC. Seismicity cross sections AA' and BB' are also shown.

4

Enclosure 1 PG&E Letter DCL-03-182 Table 1. Peak ground motions values from the Basic Seismic System digital recorders (after filtering and baseline correction).

Instrument Instrument Component Peak Peak Peak type location Acceleration Velocity Displaceme nt (cmls) k c m)

Kinemetrics Free field pit Horizontal 1 0.034 8.3 7.4 SSA (near Fitness (Channel 1) _~ _ Trailer) Vertical 0.022 7.6 6.3 (Channel 2)

Horizontal 2 0.046 8.2 4.9 (Channel 3) 1- i f. I Kinemetrics Unit 1 Horizontal 1 0.033 8.2 7.6 SSA Containment (Channel 1) base, Vertical 0.036 8.1 i 6.3 89' elev. (Channel 2) _I _

Horizontal 2 0.041 7.9 1 5.0 (Channel 31s J '-----. -, I ___________ I I -

5

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

0 0.1 a0.0.

II I,

(n I

Frequency (Hz)

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

6

Enclosure 1 PG&E Letter DCL-03-182 Frequency (Hz)

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

7

Enclosure 2 PG&E Letter DCL-03-184 Analysis of The Resultant Effect Upon Facility Features Important To Safety For The San Simeon Earthquake of December 22, 2003 Plant Systems Response:

The San Simeon Eearthquake registered 0.04g at the plant site, as read by the earthquake force monitor (EFM). The duration of the main shock was approximately 22 seconds. During this time, numerous alarms were received on both units. Many of the alarms were associated with movement of fluid levels in various systems. When the seismic activity stopped, the alarms that were received cleared and returned to normal. Operations responded by dispatching people into the power plant to visually verify 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 tripped off line due to a low-low system level lockout. This low-low system level lockout was due to the motion of the EH fluid; there were no leaks from the system. All other investigations to alarms revealed no leakage from systems and no damage caused by the earthquake. It was noted that the seismically-induced wave action in the Unit 1 spent fuel pool was of sufficient magnitude to cause a small amount of water to splash up onto the surrounding deck of the pool. Plant personnel were dispatched to clean this area.

Per Casualty Procedure (CP) M4, "Earthquake," a walkdown of the facility was conducted. All systems continued to operate normally. No visible damage was discovered. Operations personnel performed inventory checks required by CP M4; no systems were found to be leaking as a result of the earthquake. DCPP Fire Department personnel conducted plant walkdowns, including both containment structures to verify the continued integrity of fire protection features. No observable damage was discovered within the power plant and containment structures. No fire protection impairments were found. Operations personnel also performed an inventory of 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 1 containment base, top of containment, the Auxiliary Building, and the free-field pit locations (near the Fitness Trailer). The supplemental system was inoperable at the time of the earthquake, however, three temporary accelerometers located in the Auxiliary and Turbine Buildings and a permanent instrument in the basement of the control room at the 500 kV Switching Center triggered. The EFM located in the Control Room measured 0.04g on the horizontal component All functional seismic monitoring instrumentation operated as designed.

1

Enclosure 8 M

San Simeon Earthquake Nuclear Regulatory Commission Public Meeting Embassy Suites, San Luis Obispo, February 4, 2004 1

M Agenda for PG&E's Presentation

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 Earthquake Key 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

San Simeon Earthquake 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 criteria developed by Blume

HOSGRI (HE), 1977 - 7.5 magnitude earthquake on the Hosgri Fault

. NRC and PG&E agree on Hosgri evaluation criteria combining both Newmark's and Blume's versions of Hosgri response spectra 6

Seismic Design History (cont.)

Long Term Seismic Program, 1984 and on - Living Program which:

Seven year re-evaluation of the geology, geophysics, seismology, ground motion, soils-structure interaction, structural performance, and assessment of seismic margins through deterministic and probabilistic risk assessment

. 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, Vandenburg Santa Ynez Valley; SH, Solomon Hills; PH, Purisma Hills.

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I d 0 a gI San Simeon Earthquake Chronology of Events & Lessons Learned James R. Becker Vice President - Diablo Canyon Operations and Station Director 34

Chronology of Events

Both units were at full power

11 16 PST, December 22, 2003, San Simeon earthquake occurred

Implemented Procedure M-4 "Earthquake"

Unit 2 Electro-Hydraulic pumps locked out and were restarted

Operations, Engineering, and Safety Teams dispatched throughout power block 35

Chronology of Events (cont.)

Earthquake Force Monitor read 0.04 g's.

Notification of Unusual Event declared at 1122- County and NRC notified, Liaison to the County

Control room and plant walkdowns completed - no damage observed 36

Lessons Learned

An Event Response Team was formed to capture lessons learned and recommend improvements

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 and Geosciences

Security Actions 39

San Simeon Earthquake Conclusions David H. Oatley, Vice President - General Manager 40

San Simeon Earthquake Conclusions

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

ML040440460

Text

SUBJECT:

SUMMARY

Dear Mr. Rueger:

Enclosures:

SUBJECT:

Dear Mr. Rueger:

Enclosure:

SUMMARY

SUMMARY

Background

SUBJECT:

Dear Mr. Rueger:

Enclosure:

Purpose:

Purpose:

Purpose:

Dear Commissioners and Staff:

Dear Commissioners and Staff:

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