25th Annual Report by the Diablo Canyon Independent Safety Committee, July 1, 2014—June 30, 2015
Preface | Executive Summary
Volume I TOC | Volume II TOC | PG&E Response | Contact the DCISC
25th Annual Report, Volume II, Exhibit B15, Minutes of the Diablo Canyon Independent Safety Committee June 16–17, 2015 Public Meeting (Approved at the October 20, 2015 Public Meeting)
Tuesday & Wednesday, June 16–17, 2015, Avila Beach, California
Notice of Meeting
A legal notice of the public meeting was published in The Tribune, a San Luis Obispo County newspaper of general circulation, and mailed to the media and those persons on the Committee’s service list. The legal notice and meeting agenda were also posted on the Committee’s website at www.dcisc.org.
I Call to Order–Roll Call
The June 15, 2015, public meeting of the Diablo Canyon Independent Safety Committee (DCISC)was called to order by Committee Chair, Dr. Per Peterson, at 8:30 A.M. in the Point San Luis Conference Room at the Avila Lighthouse Suites in Avila Beach, California.
- Committee Member Robert J. Budnitz
- Committee Member Peter Lam
- Committee Member Per F. Peterson
Dr. Peterson welcomed those present in the room and introduced and briefly reviewed the background of the Committee’s Technical Consultants Mr. R. Ferman Wardell and Mr. David C. Linnen and Assistant Legal Counsel Robert Rathie. Dr. Peterson then introduced and reviewed the professional background of each of his fellow Members, Dr. Robert J. Budnitz and Dr. Peter Lam. Dr. Peterson recognized and introduced Ms. Maureen Zawalick, Pacific Gas & Electric Company (PG&E) Nuclear Generation Risk and Compliance Manager, who acts as the principal point of contact for the DCISC with PG&E and the Diablo Canyon Power Plant (DCPP).
III Public Comments and Communications
The Chair reviewed the procedures and advice from the agenda for the meeting concerning receipt of comments from members of the public wishing to address remarks to the Committee. The Chair advised time would be set aside for members of the public to comment on those matters listed on the agenda at the time the matter was considered by the Committee and inquired whether there were any members of the public present who wished to address remarks to the Committee on items not appearing on the agenda for the public meeting.
Mr. John Geesman representing the Alliance for Nuclear Responsibility (A4NR) was recognized. Mr. Geesman reported that Mr. David Weisman forwarded a discovery motion to the DCISC filed by A4NR which included an affidavit by Ms. Rochelle Becker, Executive Director of A4NR, which affidavit concerns emails from a former regional administrator for the Nuclear Regulatory Commission (NRC) Region IV wherein it is claimed that another former Region IV regional administrator who now serves as a consultant to PG&E voiced concerns about the seismic status of DCPP. Mr. Geesman described this as another in a long series of ‘red flags’ which the A4NR has brought to the DCISC’s attention regarding DCPP seismic issues and stated his opinion that the DCISC members were duty bound to make inquiries about the former regional administrator’s concerns. The Chair thanked Mr. Geesman for his remarks.
Dr. Lam recognized the presence in the audience of Mr. Andrew Bohan, Chief Deputy Director of the California Energy Commission (CEC). Mr. Bohan remarked this was the first public meeting of the DCISC he has had the opportunity to attend and reported CEC Chair, Dr. Robert Weisenmiller, was traveling and unable to attend. He thanked the Committee for acknowledging the CEC.
IV Consent Agenda
The only items on the Consent Agenda were approval of the Minutes of the Committee’s February 4–5, 2015, public meeting held in Avila Beach, and the Minutes of the Committee’s May 14, 2015, public meeting held in Berkeley, California.
Items were discussed and reviewed for follow up or action, and clarification was provided to the Committee’s Assistant Legal Counsel concerning certain references in the draft Minutes provided in the agenda packet for this meeting and regarding necessary typographical and editorial corrections, as well as concerning substantive changes to be made to the final version of the February 2015 and May 2015 Minutes which will be made in the final versions of both sets of Minutes which will become a part of the Committee’s 25th Annual Report on the Safety of Diablo Canyon Power Plant Operations (Annual Report) for the period July 1, 2014 to June 30, 2015.
Concerning discussion of the Minutes, Ms. Zawalick confirmed the evaluation of the root cause on the contribution of Operations personnel to the loss of the 4 kV Bus G event was completed shortly after the February 2015 public meeting and a copy will be provided to the DCISC. Mr. Wardell suggested the DCISC review be included in a future fact-finding visit. Concerning Committee follow-up on any changes in the flooding hazard at the plant Mr. Wardell stated this would be included in the Open Items List. The Members and Consultants discussed and agreed that following approval at a public meeting, fact finding reports are to be transmitted in their entirety to PG&E.
On a motion by Dr. Budnitz, seconded by Dr. Lam, the Minutes of the Committee’s February 2015 public meeting were approved as amended, subject to inclusion of the revisions discussed and changes provided to its Assistant Legal Counsel.
Concerning the Minutes of the public meeting held in Berkeley, California on May 14, 2015, for the purpose of considering and approving a consulting agreement with Structural Integrity Associates, Inc. for the services of Dr. Robert T. Sewell to review tsunami safety and tsunami issues at DCPP, the Chair reported that a call-in number was established for members of the public. A brief discussion was had concerning items for clarification and editorial correction. Dr. Lam stated that although he was unable, due to a scheduling conflict, to participate in the May 14, 2015, public meeting he wanted the record to reflect that Dr. Sewell disclosed to the DCISC in context of the consideration of a consulting agreement with the Committee that Structural Integrity, Inc. and Dr. Sewell are currently providing consulting services to PG&E on a technical matter unrelated to tsunamis.
On a motion by Dr. Lam, seconded by Dr. Budnitz, the Minutes of the Committee’s May 2015 public meeting were approved as amended, subject to inclusion of the revisions discussed and changes provided to its Assistant Legal Counsel.
V Action Items
A. Update on Financial Matters and Committee Activities.
The Chair requested Assistant Legal Counsel Rathie to provide this report. Mr. Rathie reported that the DCISC has received two quarterly payments of the funding provided by PG&E’s ratepayers under the terms of the decisions of the California Public Utilities Commission (CPUC) which established and continued the DCISC. Although the DCISC, due to the nature of its activities, expends funds at differing rates during its calendar/financial year it appears that the DCISC should finish 2015 within the amount of its grant funding with any unspent grant funds to be returned to PG&E’s ratepayers. Mr. Rathie reported that with a remaining balance from 2014 of $55,425.75 that 2014 will mark the third consecutive year in which the Committee will have returned funds to the PG&E ratepayers. Dr. Budnitz remarked that during his term of service on the DCISC the Committee has never curtailed any of its activities due to financial restrictions. Dr. Lam commented that the current fiscal health of the DCISC was due to the focus placed on that matter by the current and past Chairs. On a motion by Dr. Peterson, seconded by Dr. Budnitz, the DCISC unanimously approved the return of unspent 2014 grant funds to PG&E for credit to its ratepayers.
B. Discussion of Issues on Open Items List:
Dr. Peterson requested Consultant Wardell lead a review of items on the Open Items List, used by the Committee to track and follow issues, concerns, and information identified for subsequent action during fact-finding or public meetings. Items concerning which action was taken included the following:
|EN-20||Observe Plant Health Committee Mtg.||Observed @ 4/15FF (PL/RFW) & 5/15FF (PFP/DCL)|
|EP-5||Social Media for Emergency Response||Schedule for 8/15FF (PFP/DCL) & 9/15FF(RJB)|
|NS-9||Track INPO Areas for Improvement||Schedule 4Q15|
|RP-12||Review Radiological Release Reports||Schedule for 8/15FF (PFP/DCL)|
|ER-5||Equipment Reliability Process||Schedule for 4Q16|
|SE-38||Containment Fan Cooler Units||Add review of wireless vibration monitoring capability, Schedule 12/15FF(PFP/RFW)|
|SE-40||Monitor Status of Transformers||Schedule 1-2Q17|
|SE-49||Emergency Diesel Generators LAR||Schedule 2-3Q16|
|OM-3||Containment Closure Drill||Schedule during 1R19 (PFP) PG&E to provide date|
|OM-4||Review Outage Safety Plan||Prior to or during outage 1R19|
|SF-2||Spent Fuel Storage Casks/Pools||Delete reference to clad embrittlement risk|
|SC-4||Tsunami Hazard Analysis||Coordinate w/Dr. Sewell|
|SC-5||Personnel Seismic Safety||Schedule 12/15FF (PFP/RFW) & 2/16 PM|
|SC-7||Follow up re Shoreline Fault||Combine w/SC-3 LTSP & Joint Fault Review|
|SC-8||Post Fukushima Flooding Studies||Close after 6/15PM|
|SC-10||Tornados and Firenados||Schedule 11/15FF (RJB/DCL)|
|FP-7||Fire Doors||Schedule 1/16FF|
|LD-3||Non Licensed Training Programs||Defer to 4Q15|
|CL-2||Response from SWRCB||Monitor SWRCB action delete ref. to RCNFPP|
|10/14PM-2||Environmental Permits||Combine w/ BDB-6|
|10/14PM-3||Emergency ASW Test||Combine w/ BDB-6|
|2/15 PM-2||DCISC Public Tours||Close|
|2/15 PM-3||Seismic Hazard Tornado Diagram||Pending Report at this PM/Close or Combine w/SC-3|
|2/15PM-10||Loss of Unit-1 230 kV Off Site Power||Close|
|Various||Items Identified for Closure||Close All|
During the Open Items List discussion, Mr. John Geesman was recognized and inquired if combining the Shoreline Fault and the Long Term Seismic Program reviews included review of the potential for a joint fault seismic event and Dr. Budnitz confirmed this was what was intended. Mr. Geesman later commented the SWRCB Review Committee for Nuclear Fueled Power Plants has completed its assignment and all future action would be taken by the SWRCB but will likely be deferred pending SWRCB concern regarding drought conditions.
Following the discussion on the Open Items List the Chair called for public comments
Mr. John Geesman representing the A4NR was recognized. Mr. Geesman stated the list of contractor/experts selected by PG&E for its Senior Seismic Hazard Analysis Committee (SSHAC) review process team is largely dominated by former members of the Long Term Seismic Program team and therefore lacks fresh eyes which might have been provided by other experts. Drs. Budnitz, Peterson and Mr. Geesman discussed the issues and difficulties in having meetings dedicated to seismic review of DCPP open to all interested members of the public in venues subject to seismic activity such as exist in Berkeley, CA.
Mr. David Weisman was recognized. Mr. Weisman stated that the considerations of an earthquake occurring during an event at the University of California (U.C.) Berkeley Memorial Stadium should be borne in mind when attempts are made to dismiss the chances that an emergency situation would occur at DCPP during the Fourth of July fireworks events in the local area.
C. Nomination and Election of Chair and Vice Chair for the July 1, 2015—June 30, 2016 Term.
On a motion made by Dr. Budnitz, seconded by Dr. Lam, the Committee reelected Dr. Peterson to the position of DCISC Chair and Dr. Lam to the position of DCISC Vice Chair for terms of office from July 1, 2015 through June 30, 2016.
A short break followed.
VI Committee Member Reports and Discussion
A. Public Outreach, Site Visits and Other Committee Activities:
Dr. Lam reported that on April 27, 2015, he participated in a CEC-sponsored workshop held in Sacramento, CA on topics related to nuclear energy issues. Dr. Lam spoke concerning the issue of dry casks spent fuel storage and management at DCPP but stated his remarks were not made in terms of a consensus opinion of the DCISC but rather in context of his participation as a private individual and in furtherance of the Committee’s obligation for members of the DCISC to conduct public outreach. Dr. Lam observed the CEC has made several recommendations concerning DCPP in the past including that the plant return the spent fuel pools to an open rack configuration and accelerate the movement of spent fuel from the spent fuel storage pools into dry cask storage at the plant.
The Committee members and consultants reviewed and scheduled fact-finding visits and public meetings of the Committee as follows:
Public meetings of the Committee were rescheduled and confirmed for: October 20–21, 2015, a change of dates from the previously scheduled October 21–22, 2015, and confirmed the date of February 3–4, 2016, and scheduled a public meeting for June 21–22, 2016.
Fact-finding visits were confirmed and scheduled as follows:
-  July 29–30 PFP/DCL (changed from August 5–6); September 9 RJB to observe the full scale Emergency Training Drill; September 29–30 PL/RFW; November 18-19 RJB/DCL; and December 9–10 PFP/RFW
-  January 19–20 PL/DCL; March 16–17 RJB/RFW; April 20–21 PL/DCL; May 17–18 PFP/RFW; July 26–27 PFP/DCL; August 9–10 RJB/RFW; September 20–21 PL/DCL
The Members and Consultants observed that the fact-finding schedule is subject to change based on emergent activities at DCPP. The Committee requested and Ms. Zawalick agreed that these dates for the DCISC’s future public meetings be provided to the NRC Senior Resident Inspector for DCPP to determine whether the NRC might coordinate its schedule for a public meeting during the same week a DCISC public meeting is scheduled.
B. Documents Provided to the Committee:
Mr. Rathie directed the Committee's attention to the list of documents received since its last public meeting in February 2015. A copy of the list was included with the public agenda packet for this meeting. He also observed that the public agenda packet contains copies of all correspondence received by the Committee since its last public meeting in February 2015.
VII Staff-Consultant Reports & Receive, Approve and Authorize Transmittal of Fact Finding Reports To PG&E
The Chair requested Consultant Wardell to report on a fact-finding visit to DCPP. Mr. Wardell reported on the April 21–22, fact-finding visit to DCPP with Dr. Lam. Mr. Wardell reviewed the items and topics reviewed with PG&E during that visit.
- Meeting with NRC Senior Resident Inspector—Mr. Wardell described the meeting as useful and including a discussion of issues concerning the emergency diesel generators (EDGs), the plant’s severe weather policies and the recent seismic analyses by PG&E.
- EDG Status—the EDGs function as the ultimate power source for the plant when other power sources are lost. Each unit has three EDGs and each EDG is designed to start automatically upon loss of power. The system health for each unit 1 is rated Yellow due to margin management, full load rejection and capability issues. Tests show that the EDGs are fully capable of performing their function but a License Amendment Request (LAR) has been submitted by DCPP to the NRC which is awaiting completion of review. Unit-1 (U-1) EDGs are expected to return to White health status by September and to Green by the end of 2015. Unit-2 (U-2) EDG health status is expected to return to White by June 2016 and to Green in due course. Mr. Wardell reported EDG 1-2 (U-1 Number 2 EDG) is close to exceeding its unavailability goal and EDG 2-3 is having reliability issues. The EDGs are currently rated in Yellow health status and DCPP has developed actions to return them to White and subsequently to Green status. Mr. Wardell recommended the Committee continue to follow the health status of the EDGs.
- Meteorological Information and Dose Assessment (MIDAS)—MIDAS is a computer-based analysis program that is used to predict the path and magnitude of a radioactive release during an accident at the plant. It is a program in use industry-wise and DCPP has upgraded MIDAS to its third edition or version which provides the capability of taking in several meteorological inputs from different locations and giving several discharge locations, with accordingly more accuracy and versatility than previous versions of MIDAS.
- Salt Deposition Rate Update—Mr. Wardell reported the fact-finding team reviewed this issue in terms of the proposal to replace once-through cooling with cooling towers which would employ evaporative saltwater which would increase salt deposition at the plant site and also in view of the fact that DCPP operates in proximity to the Pacific Ocean which Mr. Wardell observed provides excellent cooling water capabilities but results in a great deal of salt being transported in the air. Dr. Peterson requested that data be provided on duration of sample collection and the rate of deposition in order to be better able to compare previous data on salt deposition.
- Design Quality Status—Mr. Wardell reported that during the seventeenth refueling outage for U-1(1R17) DCPP experienced design quality problems with major plant modifications. A root cause evaluation was performed and corrective actions taken. During 1R18 the DCPP Engineering organization found the corrective actions effective but the Quality Verification organization did not entirely concur and required further monitoring. Engineering determined 92 percent of 64 projects were completed without design quality issues but the 8 percent which did have such issues was not an acceptable result and design quality performance will be reviewed during 1R19. Mr. Wardell recommended a fact-finding following 1R19 to review the results of the effectiveness review. The programmatic health status of the Design Change Program is currently rated Green.
- Spent Fuel Cooling System Review—Mr. Wardell reported there are two spent fuel pools at DCPP and each pool has its own cooling system consisting of two pumps and one heat exchanger. The cooling systems are working well and the system health is rated Green for both. There is, however, a potential vulnerability due to the single heat exchanger for each and DCPP has purchased a portable cooling system capable of being moved from one unit to the other.
- Attend Plant Health Committee (PHC)—the PHC received a report describing an update on the 480 V System which was previously in White health status but which changed to Green by the time of the PHC meeting. Mr. Wardell reported the significant challenge to the 480 V System is due to the age of the breakers, which date from the original plant, and DCPP has both a replacement program and a preventive maintenance program for the 480 V System. The DCISC fact finding team found the PHC meeting to be run effectively and efficiently.
- FLEX Update—FLEX is a post-Fukushima program initiated by the U.S. nuclear industry to provide the ability for a flexible response to beyond design basis events (FLEX is not an acronym). Mr. Wardell reported procurement of FLEX equipment is on schedule as are the development of procedures and procedural training. In response to Dr. Budnitz’ inquiry, Mr. Wardell reported that the FLEX program is on schedule.
- Licensing Basis Verification Program (LBVP) Update—Mr. Wardell described this as an extensive and thorough review of each and every system, component, program, etc., when compared to the DCPP Final Safety Analysis Report (FSAR). DCPP has committed to the NRC to complete the LBVP by the end of 2015. The fact-finding team received information on the seismic qualifications of the new reactor vessel heads and new steam generators. The LBVP review discovered that due to a misinterpretation by the vendor equipment was not designed to the fullest extent for seismic and loss of coolant accident (LOCA) loads. A prompt operability assessment (POA) was completed which justified continued operation with the loading as calculated by the vendor and margins were judged to be sufficient until reanalysis is completed. That reanalysis is in progress and is due to be completed by mid-October 2015. Mr. Wardell stated this is a matter on which the DCISC should conduct follow up.
- Winter Storm Experience—procedures were reviewed and there were no significant storms last winter.
- Operational Decision Making (ODM)—Mr. Wardell stated ODM is a systematic method used mainly by Operations to address degraded conditions including, but not limited to, Containment leakage, vibration, fuel defects, and aggregate chronic equipment deficiencies. The Corrective Action Program (CAP) is used with ODM and a multifunction decision team gathers data and testing results to reach a joint decision. The fact-finding team reviewed three ODM actions including for the pressurizer power operated relief valves, a reactor trip, and a Reactor Coolant System (RCS) unidentified leak. An effectiveness review is performed approximately six months following ODM actions and the fact-finding team reviewed three ODM effectiveness reviews. Mr. Wardell described the ODM review as satisfactory and the process as effective.
- Dr. Lam Meeting with DCPP Site Vice President—to discuss the items reviewed during the fact-finding.
Upon a motion by Dr. Budnitz, seconded by Dr. Peterson, the April 21–22, 2015 Fact Finding Report was approved and its transmittal to PG&E authorized.
Once the Committee’s fact finding reports are approved at a public meeting they are no longer considered to be in draft form and are made available in a binder for inspection by members of the public, together with information concerning the professional backgrounds of the Committee’s technical consultants involved with preparation of its fact finding reports. Fact finding reports become part of DCISC’s Annual Reports.
Mr. Wardell continued his report with a summary description of the June 10–11, 2015, fact-finding visit to DCPP with Dr. Budnitz. A full report on this fact-finding visit will be presented during the October 2015 public meeting. Item reviewed during that visit include:
- Air Operated Valve Program—program health status was Green.
- Refueling Outage 1R19—Outage Safety Plan was not reviewed.
- Lunch with North American Young Generation in Nuclear—a volunteer internal organization to DCPP formed to network concerning plant issues and conduct outreach outside DCPP.
- EDG Update—reviewed issues regarding unavailability for EDG 1-2 and reliability issues with EDG 2-3.
- Institute of Nuclear Power Operations (INPO) Update—INPO evaluation is scheduled for August 2015.
- Control Room Simulator—Mr. Wardell stated the Simulator was a mock-up of the U-1 Control Room which can be used for transient analysis and provides a valuable tool for testing operators. DCISC representatives discussed how the Simulator plans to accommodate the use of FLEX equipment. Although there is no requirement by the NRC to incorporate FLEX equipment or procedures in the Simulator the plant does plan to incorporate the most important elements of FLEX including the emergency addition of water and emergency power hookups with Simulator exercises.
- Control Room Shift Turnover—Mr. Wardell reported the DCISC representatives visited the Control Room to observe a shirt turnover.
- Integrated Risk Assessment Program—fact-finding team previously reviewed primarily on-line maintenance risk and the Program has now been expanded to perform integrated risk analysis of almost all evolutions and activities.
- Reactor Protection System Digital Upgrade Status—Mr. Wardell described this system as functioning to shut down a reactor if temperature, pressure, or neutron flux are out of the norm. The current digital system is to be replaced with a new digital system and DCPP has submitted a license amendment request (LAR) to the NRC for the upgrade and expects approval in early 2016.
- Meeting with DCPP Station Director.
- Meeting with NRC Senior Resident Inspector.
- Integrated Equipment Reliability—Mr. Wardell reported DCPP management has made a decision to make the Integrated Equipment Reliability Program a plant-wide program under a station director as opposed to its current engineering-centered focus. He reported that four items from a top ten priority list of items to be addressed have already been moved off that list and replaced by others.
The fact-finding team’s plans to attend a meeting of the Plant Health Committee and receive a review of the Emergency Preparedness Program were cancelled.
The Chair requested Assistant Legal Counsel Rathie to report on administrative, regulatory and legal matters.
Mr. Rathie reported that Dr. Lam has been reappointed by the Chair of the CEC to a three-year term on the DCISC for the period July 1, 2015 to June 30, 2018. Mr. Rathie reported that on May 14, 2015, the DCISC approved at a public meeting, held in Berkeley, CA for that purpose, a contract with Structural Integrity Associates, Inc. for the services of Dr. Robert T. Sewell to conduct a review of the tsunami hazard at DCPP and its environs. He reported that California Senate Bill 657 introduced by Senator William Monning which, if approved, would continue the work of CPUC Independent Peer Review Panel until January 2025 to review enhanced seismic studies and surveys was presently before the Senate’s Energy, Utility and Communications Committee. Mr. Rathie reported the public tour of DCPP scheduled in conjunction with this public meeting was fully subscribed and the reservations filled quickly. A notice was sent out soliciting persons now receiving notice of DCISC public meetings by U.S. mail to have the option of receiving notice by email. Mr. Rathie reported that for the first five months of 2015 the DCISC website has averaged 756 unique visitors every month coming principally from the U.S., Germany, Canada and the Ukraine with the top sites visited including the information on plant tours, agendas and notices for public meetings, and to download information from DCISC Annual Reports.
The Chair requested Consultant Linnen to report on the next fact-finding visit to DCPP. Mr. Linnen reported on the March 30-April 1, 2015, fact-finding visit to PG&E’s San Francisco headquarters and to DCPP with Dr. Budnitz. Topics reviewed with PG&E during that visit included the following.
- PG&E Tsunami Risk Analysis—Mr. Linnen reported that during their visit to the PG&E corporate office in San Francisco, the fact-finding team received information on the tsunami analysis together with Dr. Robert T. Sewell who participated by telephone. Dr. Sewell prepared in 2003 a Tsunami Study of the site of DCPP for the NRC, which kept this study in draft form and until recently withheld from public disclosure. Dr. Sewell’s 2003 tsunami study was recently released in response to a request under the Freedom of Information Act (FOIA) on behalf of the DCISC. Dr. Sewell is now under contract with the DCISC to perform further review of the tsunami hazard at DCPP. Mr. Linnen stated that as PG&E is presenting a report on external flooding risk at DCPP at this public meeting he would not cover this item further in his report.
- PG&E Seismic Study—Mr. Linnen stated that as PG&E is presenting a report on this topic at this public meeting he would not cover this item in this report.
- Probabilistic Risk Assessment (PRA) Program Status—the DCISC team discussed with DCPP representatives human error probabilities used in the seismic PRA and a recent LAR which has been submitted to the NRC for revising technical specifications based upon a generic issue pertaining to the impact of debris generated from a postulated LOCA that might accumulate on the Containment sump. Dr. Budnitz reported DCPP will be initiating in one year a full scope PRA for outage shut down conditions and is awaiting completion of a trial of methodology standards developed for this effort. The seismic PRA is also being updated.
- Fire Protection System and Program Health—overall the Program’s health is rated as White status, representing good health but with issues to be addressed due to degradation observed in fire suppression piping for each unit. Plans are being developed to replace piping and issues continue to be addressed due to deficiencies with some fire doors which the DCISC has reviewed on several occasions. The program health is expected to return to Green status this year. Mr. Linnen commented that DCPP is one of only three nuclear power plants in the U.S. to have an on-site fire department.
- Spent Fuel Pools and Related Equipment—the fact-finding team toured the U-2 Spent Fuel Pool and found its condition to be good.
- Safety Injection Pumps—Mr. Linnen stated there are two pumps for each unit and the pumps are located in rooms in which flood levels due to external and internal flooding could have an impact. The flooding implications have been evaluated and determined not to exceed the height of the pump motors and associated instrumentation and therefore the pumps are judged to be immune to a design basis type of flooding event.
- Safety Conscious Work Environment (SCWE) & Human Performance Program—Mr. Linnen reported the SCWE topic is closely tied to human performance as SCWE focuses upon human behaviors and uses data obtained by observation to determine how well individuals are functioning and to identify and implement change as required. SCWE Program also uses coaching by supervisory and management personnel who make observations and receive feedback which is an important element of a SCWE. Mr. Linnen stated that while a substantial amount of data has been gathered the program is in an early stage but the DCISC representatives were impressed with the results achieved so far. Dr. Budnitz commented SCWE is a topic which is receiving attention both within the nuclear industry in the U.S. and around the world in the attempt to better understand what environments are conducive to and adverse to human performance. The NRC, INPO and the U.S. Department of Energy (DOE) are also engaged in these efforts. Dr. Budnitz observed that the issues are not engineering-related but rather management-related. Mr. Linnen stated there is a challenge in that workers can sometimes feel they are being critically evaluated as opposed to coached for success.
- System Engineering Program—system engineers are responsible for recommending plant actions to be taken in response to any health issues that arise with their systems. Mr. Linnen stated the DCISC team found the program to be well conceived and structured as an effective means to monitor the health of plant systems. The number of open items related to system issues has been reduced from more than 500 to less than 300. He reported the top two issues on the System Engineering Program’s top ten list have to do with system health involving the emergency diesel generators (EDGs). Mr. Linnen stated the DCISC should follow up on the status of the System Engineering Program’s top ten list within one year.
- Compressed Air System—the DCISC team followed up on a review conducted in September 2014 during which the DCISC learned one of the station’s three primary air compressors is located outdoors adjacent to the Turbine Building. Of the four back-up air compressors none had been operated in twenty years. Mr. Linnen stated this review found the air compressors to be in good condition, with the outside and inside compressors all found clean, painted and free of any rust. Plans are now in place to commence testing the four back-up air compressors.
- Meeting with NRC Resident Inspector—Dr. Budnitz stated the DCISC representatives met with NRC Resident Inspector John Reynoso. Mr. Reynoso has a background as a reactor operator at a plant comparable to DCPP before his service with the NRC and holds a Senior Reactor Operator license. Dr. Budnitz commented it was unusual and valuable for a resident inspector to have such a background. Dr. Lam reported the Senior Resident Inspector at DCPP, Mr. Thomas Hipschman, previously served as the Executive Assistant to the Chairman of the NRC and brings a great deal of policy and technical experience to his work at DCPP. Dr. Budnitz agreed and commented that DCPP and the NRC are both very well served by the competence of the two NRC resident inspectors.
- DCISC Member Budnitz meeting with Vice President Nuclear Services and Site Vice President.
Upon a motion by Dr. Budnitz, seconded by Dr. Peterson, the March 30-April 1, 2015 Fact Finding Report was approved and its transmittal to PG&E authorized.
The Chair requested Dr. Budnitz to preside over review of the next item and requested that Consultant Linnen continue his report with a report on the next fact-finding visit to DCPP. Mr. Linnen reported on the May 19–20, 2015, fact-finding visit to DCPP with Dr. Peterson. Topics reviewed with PG&E during that visit were reviewed as follows:
- Plant Health Committee (PHC) Meeting—Mr. Linnen reported the PHC reviewed the Reactor Coolant System’s (RCS) health for both units which due to issues with system components has been rated deficient for approximately one year and is expected now to return to a healthy status for U-1 during refueling outage 1R19 and for U-2 during the first quarter of 2016. Mr. Linnen stated the PHC participants were well prepared and the meeting was conducted in a professional manner with participants engaged in providing input and asking questions. Actions were assigned and captured for future reference and the DCISC team was impressed by the conduct of the PHC meeting.
- Office Seismic Safety—the DCISC team toured the Administration Building fifth floor with the DCPP Director of Site Services and some cabinets and shelving were found not to be secured, although Mr. Linnen stated DCPP appears to have more of an appreciation due to the DCISC’s continuing emphasis concerning this topic. He reported the DCPP Fire Chief will be including office seismic safety issues as part of periodic fire inspections.
- Seismically Induced System Interactions (SISI) Housekeeping Program—Mr. Linnen stated that as PG&E is presenting a report on this topic at this public meeting he would not cover this item in this report.
- Seismic Reviews of DCPP’s Replacement Steam Generators and New Reactor Vessel Heads—Mr. Linnen remarked this was the team’s first review of this topic and that PG&E is engaged in a seismic fragility probabilistic risk analysis intended to provide information on the likelihood of different plant damage which might be caused by earthquakes, such as a LOCA involving either the new steam generators or the new reactor vessel heads. Dr. Peterson remarked the DCISC should schedule follow up investigation into the plans to add instrumentation within key structures and on key safety-related components within the plant to gather data about how the structures or components respond during earthquakes and how energy is transmitted through the soil around the site together with the response of the equipment. Dr. Peterson observed this topic might potentially trigger a future recommendation by the DCISC. Dr. Budnitz commented experts believe that systems such as the steam generators generally have a good deal of extra margin but the DCISC will review PG&E’s reevaluation of the plant’s seismic capacity. Dr. Peterson observed that high pressure equipment and piping generally have a very robust design basis in order to be capable in terms of internal pressure and this results in corresponding margin relative to seismic loads.
- Benchmarking Program—Mr. Linnen reported this is a program used by all nuclear facilities to share good practices and occurs formally through visits to other plants and informally by telephone and through an exchange of correspondence, and by attendance at topical conferences. He stated DCPP has maintained an active Benchmarking Program and provided examples in the areas of emergency operating procedures, severe accident management and extreme mitigation guidelines, and post Fukushima response support guidelines where the plant has shared and received valuable information with other nuclear facilities.
- Operating Experience Program—described by Mr. Linnen as another industry-wide program in which U.S. nuclear plants can share information regarding events and problems that have occurred. Mr. Linnen described the Operating Experience Program at DCPP as active and engaged and the DCISC fact-finding team had no recommendations.
- Potential for Chloride Stress Induced Corrosion Cracking (CSCC) of Multipurpose Canisters (MPCs) in the Independent Spent Fuel Storage Installation (ISFSI)—Mr. Linnen reported that various types of stainless steel used for the MPC’s have differing susceptibilities to CSCC. Each MPC is inserted into a high integrity storage module (HI-STORM) which allows air to flow around the MPC and in a salty air environment such as that at DCPP there is potential for salt deposition on the outside of the MPC which could lead to corrosion and, in time, result in CSCC. Mr. Linnen reported the MPCs presently on site at DCPP are on the lower end of resistance to CSCC but he reported that the corrosion rate is dependent upon temperature, with lower temperatures offering greater potential for a high rate of corrosion. In humid conditions salt can plate-out on the surface of the MPC but with lower temperature salt plating is likely to be of a softer form, termed deliquescence, meaning the salt has not hardened on the MPC and in that form the salt can be more aggressive as far as its corrosion rate. DCPP and the industry are in the process of evaluating these issues. Dr. Budnitz remarked that this is a concern the DCISC will want to make sure is understood and that there is no threat in the next few years. Mr. Linnen stated that the fact-finding team suggests that DCPP may find it valuable to periodically check and track the temperature on the surface of its MPCs as deliquescence can be prevented if the MPC surface temperature is maintained sufficiently high above the outside ambient air temperature. In response to Dr. Lam’s observation, Dr. Budnitz replied that CSCC on the MPCs at DCPP does not appear to represent an imminent threat to safety but the matter is worthy of further inquiry.
- External Flooding Assessment—Mr. Linnen stated that as PG&E is presenting a report on this topic at this public meeting he would not cover this item in this report.
- Quarterly Station Performance Review Meeting.
- Discussion with NRC Senior Resident Inspector.
- Discussion with PG&E Chief Nuclear Officer.
Following Mr. Linnen’s presentation, Mr. John Geesman, representing the A4NR was recognized. Mr. Geesman stated that his concern about CSCC is whether or not there is any ability currently to predict a trend that would assist in defining a relevant time horizon that one should be concerned with. He stated that given the time that spent fuel is expected to be on site at DCPP it would be useful to be able to predict a relevant time horizon. Mr. Geesman stated that media reports have stated PG&E initially conducted its review of the replacement steam generators and reactor vessel heads against the Hosgri Fault evaluation criteria and did not require analysis of a seismic event on the Hosgri Fault in conjunction with a LOCA event and he inquired whether during the fact-finding visit any explanation was given for not including the LOCA scenario in the initial analysis and review and whether that omission should be cause for concern. Mr. Geesman observed that as the DCISC has included recommendations about office seismic safety in its two most recent Annual Reports the fact that issues were discovered during the fact-finding reported by Mr. Linnen might suggest evidence of concern regarding PG&E’s corporate culture as it may be that DCPP personnel simply do not accept the likelihood of such a scenario with sufficient probability to take corrective actions. Mr. Geesman observed that relative to CSCC the issue may be of lesser direct concern at DCPP than at the now decommissioned San Onofre Nuclear Generating Station (SONGS) in terms of the A4NR’s view as to the proper size of the nuclear decommissioning trust for SONGS.
Dr. Budnitz, responding to Mr. Geesman’s observations, stated that with reference to CSCC the community of experts now believe that it could take decades for CSCC of the MPCs to become a problem but there is not yet a time horizon developed through the ongoing analysis that is now occurring. Dr. Budnitz reported that the DCISC review during the fact-finding of the seismic qualifications of the new steam generators and new reactor vessel heads was not conducted as a review of whether those systems met their respective licensing criteria but rather was conducted in terms of the ultimate seismic capacity and ability to perform their safety functions for those systems and in that context, the LOCA scenario is not directly relevant.
Ms. Sherry Lewis, representing the group San Luis Obispo Mothers for Peace, was recognized. Ms. Lewis inquired how long the DCISC would remain in operation. Dr. Budnitz replied that, as the DCISC is charged with reviewing operational safety at DCPP, it is likely that the DCISC would continue operations as long as DCPP operates but that matter is subject to the determination of the CPUC which created the DCISC. Ms. Lewis stated that given that residue from DCPP’s operations will remain at the site, this could be a problem for the local community.
Upon a motion by Dr. Lam, seconded by Dr. Budnitz, the May 20–21, 2015 Fact Finding Report was approved and its transmittal to PG&E authorized.
Copies of correspondence sent and received at the office of the Committee's Legal Counsel since the last public meeting of the Committee in February 2015 were included with the public agenda packet for this meeting and previously called to the Committee’s attention.
IX Adjourn Morning Meeting
The Chair adjourned the morning meeting of the DCISC at 12:20 P.M.
X Reconvene For Afternoon Meeting
Dr. Peterson reconvened the afternoon meeting of the DCISC at 1:30 P.M.
XI Committee Member Comments
There were no comments at this time from the Committee members.
XII Public Comments and Communications
Dr. Peterson invited any member of the public present to address comments to the Committee on topics not on the agenda.
Ms. Sherry Lewis representing Mothers for Peace was recognized. Ms. Lewis stated NRC Inspection Report ML 14349A485 included statements regarding the licensee’s (PG&E) operability determination concerning the seismic study of the Shoreline Fault zone which indicate that the Shoreline Fault might be more capable than determined in a 2011 study, but the NRC concludes the deterministic response spectra developed in the Central Coastal California Seismic Imaging Program (CCSIP) are still bounded by those of the Hosgri Fault, and as analyzed in PG&E’s Long Term Seismic Program (LTSP)described in DCPP’s current licensing basis and so the plant should be able to withstand any earthquake within its double design basis with an adequate reserve margin. Ms. Lewis stated there is a problem with this analysis as a more recent evaluation of the Hosgri Fault has shown it has capabilities considered greater than the double design basis and therefore the margin would not be as great as previously calculated. She stated Dr. Blakslee, a geophysicist and former member of the California Assembly, authored Assembly Bill (AB) 1632 to require PG&E to conduct additional seismic studies. Ms. Lewis stated she was bothered by the statements in the NRC Inspection Report which indicate that the margin is adequate and that she believes Dr. Blakeslee would also question this conclusion. She commented that as more faults are identified in the vicinity of DCPP, or found to be more dangerous than previously believed, the ground motion prediction equations are altered to make the end result to be always within the NRC’s licensing basis for DCPP and she stated this is not correct. She requested the Committee to review Dr. Blakeslee’s statements on this issue and to get involved and address these issues in its public meetings.
Mr. John Geesman representing the A4NR was recognized. Mr. Geesman posed two questions to the Committee on behalf of the A4NR: (1) with respect to PG&E’s determination as to the capability of the Shoreline Fault, whether PG&E has specifically evaluated the prospect of a joint rupture of the Shoreline, San Simeon, and the Hosgri Faults under the same assumption it used for its Shoreline Fault determination and why joint ruptures are not considered in all PG&E’s deterministic assessments; and (2) with respect to Dr. Blakeslee’s concerns shouldn’t the variable ground motion prediction equations (GMPE) be isolated to determine what influence this variable has played in PG&E’s previous assessments of the seismic risk at the plant? Mr. Geesman remarked there have been five or six different GMPEs developed since the plant received its original license and the same GMPE should be used to rerun each calculation to isolate the influence of the GMPE.
Mr. David Weisman of the A4NR was recognized. Mr. Weisman reported that California Senate Bill (SB) 657 passed out of the Senate Utilities and Communications Committee without opposition. He reported this bill would continue the CPUC Independent Peer Review Panel (IPRP), which is tasked with conducting independent review of PG&E’s enhanced seismic studies and surveys, until January 1, 2025, the end of the plant’s current licensing term. Mr. Weisman read quotes from SB 657's author Senator Monning and from San Luis Obispo County Supervisor Bruce Gibson who serves on the IPRP. SB 657 will now move from the Senate to the Assembly. Mr. Weisman also reported on AB 361 by Assembly Member Achadjian which would provide for extending funding from the CPUC for San Luis Obispo County’s Office of Emergency Services and for emergency planning services from 2019 until 2025. Mr. Weisman stated that AB 361 has passed out of the Assembly and will now move on to the California Senate.
Mr. Randall Morton was recognized. Mr. Morton stated he worked as a junior engineer for Westinghouse in 1972-1973 and worked at DCPP during that time on the turbine, the generators and the plant’s auxiliary equipment. Mr. Morton stated he was disappointed to see that there were so few persons present to support DCPP as it is the only operating nuclear power plant in California and it would be a tragedy if it were to close.
Ms. Elizabeth Brousse of Mothers for Peace was recognized. Ms. Brousse stated she enjoys the articles written by PG&E meteorologist John Lindsey and she stated Mr. Lindsey often ends those articles with a statement that DCPP is “Clean and green.” She inquired what the Committee members would say about the use of the term “Clean and green” in reference to DCPP.
Ms. Linda Seeley of Mothers for Peace was recognized. Ms. Seeley stated that there are many tourists in the local area during this time of year and that there are four major development projects in planning stages in the Avila Beach area at the present time. Ms. Seeley stated there is but a single road with two lanes providing access to the Avila Beach area and if there was a release of radiation from DCPP there would be no reasonable way to evacuate the area effectively. Ms. Seeley stated that the emergency evacuation plans need to be reviewed with respect to the significant increase in population in the areas around DCPP.
Ms. Lester Goldfisher was recognized. Mr. Goldfisher stated that there have been several analyses of seismic issues in the vicinity of DCPP and he questioned which of these analyses the public should credit as being the most accurate. He stated that with respect to analyses done by or on behalf of PG&E there is an economic factor involved in these analyses which might tend to influence their conclusions.
Dr. Peterson stated he appreciated Ms. Seeley’s comments and the DCISC should take an action to review the effect of an increase in local population on emergency response planning at a future fact-finding. Dr. Peterson stated the DCISC is performing an independent assessment on tsunami risk at DCPP which will include the areas of Avila Beach, Pismo Beach and Morro Bay. A principal focus of that assessment will be on the understanding of tsunamis which might be induced by submarine landslides and the impact on the need to maintain access to the plant and to maintain the ability to perform evacuations.
Dr. Budnitz remarked concerning Mr. Geesman’s comments that when an earthquake occurs the seismic energy needs to go from the fault to the plant before it can harm the plant and it is how that seismic energy is transmitted that is described by the GMPEs which are very site specific, as the propagation of the motion includes both attenuation and changes in frequency as the energy moves through various media as well as amplification in some frequencies due to the nature of the soil. Dr. Budnitz reported that since the original analysis was done in the 1970's the seismic community has greatly increased its understanding of ground motion movement and this understanding is captured in modern GMPEs and this is the reason, along with more site-specific data, that PG&E has used different and more modern GMPEs in its analyses to result in improvements over previous analyses. Dr. Budnitz stated Dr. Blakeslee’s complaint regarding PG&E’s use of changing GMPEs is an invalid complaint. Dr. Budnitz stated he understood Mr. Geesman’s request to use previous GMPEs in a reanalysis for comparison purposes but that process would not validate the older GMPEs. Dr. Budnitz stated the seismic community believes the modern GMPEs are more accurate but uncertainties still exist and review by a number of groups continues.
In response to Dr. Budnitz’ remarks, Mr. Geesman stated that the latest GMPE could be used to compare the previous seismic source characterizations and he further remarked that the available data from the site, two earthquakes that populate the ground motion, may be conflated as data has also been included from around the world and both the NRC and the IPRP have been critical of PG&E concerning this data. Mr. Geesman remarked that he is disturbed by information in the IPRP’s Report No. 9 which maintains that no matter which of the earlier spectra one chooses to use, that several of the scenarios are in excess of those criteria on which the plant’s margin is based. In response to Dr. Budnitz comment that Dr. Budnitz’ previous remarks were not in reference to criteria but to the strength of the plant, Mr. Geesman inquired as to how that strength is quantified and Dr. Budnitz stated that this was quantified years ago and it is now being requantified but it is important to recognize that the earlier quantification was of the hazard and not the margin.
Ms. Lewis was again recognized and stated she did not believe Dr. Budnitz statements and PG&E did not acquire all the necessary data and what data PG&E has acquired is not sufficient. Ms. Lewis stated she disagreed with Dr. Budnitz use of the term “Complaint” in reference to Dr. Blakeslee’s observations.
Dr. Lam stated he wished to inject a healthy dose of skepticism to the discussion as he believes that seismic science is far from mature as it cannot determine how soon, how large or how near the next seismic event may be and public inquiry in this matter is valuable. Dr. Lam stated with reference to Ms. Seeley’s comments that the adequacy of the existing federal and state rules may be grossly inadequate and that analysis should be the subject of further inquiry by the DCISC. As to Ms. Brousse’s remarks, Dr. Lam stated he was not a proponent or an opponent of nuclear technology and has seen in his service as an NRC administrative judge the debates about the use of and penalties involved with the use of nuclear technology.
Dr. Budnitz stated that Dr. Lam should consider that a personal decision to fly on an airplane is taken in light of the fact that no one can predict when the next crash will occur and yet most people do not refuse to fly and consider air travel to be adequately safe on that basis. Dr. Budnitz stated that the proper inquiry concerns how frequent do these accidents occur. Dr. Budnitz observed that Dr. Lam’s posing of the questions as to how soon, how big or how near a seismic event may be is an invalid proposition and a judgment concerning whether DCPP is adequately safe from seismic events requires an understanding of how frequently these events might occur and this is the knowledge the seismic community seeks. Dr. Lam stated in response that if someone could tell him that a large seismic event would not occur in the next 50 years he would rest assured of DCPP’s safety.
Dr. Budnitz remarked, concerning the use of the term “Clean and green,” operation of a nuclear plant, in the absence of an accident, is environmentally benign and it is not normal operation which is a cause for concern but the accidents which can occur from that operation as well as generation of waste which is of concern to what is otherwise a “Clean and green” technology.
Mr. David Weisman of the A4NR was recognized. Mr. Weisman remarked the reason that most people accept the risks associated with air travel with confidence is that adequate data points exist due to the fact that aircraft are manufactured by the thousands using the same equipment and data on their operation is continually being acquired so that a safety basis is developed such that insurance companies are able to underwrite aircraft operations.
XIII Information Items Before the Committee
The Chair requested Mr. Cary Harbor, DCPP Director of Compliance, Alliance and Risk to introduce the first of the informational presentations requested by the Committee for this public meeting.
Mr. Harbor thanked Dr. Peterson on behalf of PG&E for the opportunity to present information to the Committee and introduced Mr. Tom Baldwin, DCPP Director of Site Services, and stated Mr. Baldwin has more than 30 years’ experience in the nuclear field and holds a Bachelor of Science Degree in Mechanical Engineering and a Professional Engineer’s License and has previously held leadership roles in Regulatory Compliance, and Engineering organizations at DCPP.
Review of NRC Performance Indicators, Licensee Event Reports and NRC Notices of Violations
Mr. Baldwin reported his presentation would cover the time between February 2015 and May 2015, particularly in the area of NRC oversight. He stated in summary all NRC performance indicators meet NRC green performance expectations. Five violations of very low safety significance were reported since the last DCISC meeting, one of which was identified by PG&E concerning correction of a procedure in its emergency response plan. He stated his presentation would cover more than four months of NRC inspections involving 1,000 hours by both on-site and specialized inspectors.
Mr. Baldwin reviewed two slides with a chart which summarized the NRC Performance Indicators that all nuclear stations report to every quarter. Mr. Baldwin stated that DCPP continues to meet all NRC performance indicator thresholds and sets more rigorous thresholds for the Performance Indicators than the thresholds set by the NRC, and then DCPP monitors those on a continuous basis in order to enter areas of declining performance into the Corrective Action Program to take prompt action before they can impact the performance on the NRC’s indicators. The NRC Performance Indicators, which are also available to members of the public on the NRC’s website, include:
- Unplanned Scrams per 7000 Critical Hrs.
- Unplanned Power Changes per 7000 Critical Hrs.
- Unplanned Scrams with Complications
- Safety System Functional Failures
- Mitigating Systems Performance Index, Emergency AC Power System
- Mitigating Systems Performance Index, High Pressure Injection System
- Mitigating Systems Performance Index, Heat Removal System
- Mitigating Systems Performance Index, Residual Heat Removal System
- Mitigating Systems Performance Index, Cooling Water Systems
- Reactor Coolant System Activity
- Reactor Coolant System Leakage
- Drill/Exercise Performance
- ERO Drill Participation
- Alert & Notification System
- Occupational Exposure Control Effectiveness
- Radiological Effluent Occurrence
Mr. Baldwin reported on the two Licensee Event Report (LERs) initiated and issued by DCPP over the last several months as follows:
- LER 1-2014-004, issued March 30, 2015, for actuation of six emergency diesel generators (EDGs) due to loss of offsite power. This event occurred on October 31, 2014, during a moderate rainstorm which caused rainwater to mix with salt and dust contamination on electrical insulators in the 230 kV switchyard which resulted in a flashover. This actuated protective relays to isolate the 230 kV switchyard and the EDGs started automatically and remained in standby as they were not needed because power remained available from the 500 kV System. Mr. Baldwin stated the insulators in the switchyard have been replaced with insulators providing a greater capacity to resist such events.
- LER 2-2014-002, issued May 7, 2015, for U-2 plant shutdown required by Technical Specifications (TS). This event occurred in August 2014 during mechanical maintenance on EDG 2-2 when a cap screw holding a fuel injector on one cylinder was found to be cracked. The cap screw was replaced and all other EDGs were inspected with one other EDG found with a bolt that showed signs of degradation. Mr. Baldwin reported that the bolt was replaced. When performing a startup test of that EDG a fuel oil booster pump seal failed and leaked oil. As the EDG could not be repaired within the time allowed by TS, the plant was shut down.
Mr. Baldwin reported on five violations received from the NRC2 as follows:
- NCV (Green)—for failure to implement Fire Protection Program (C-C Aspect H.5 Work Management). Discovered during U-2 refueling outage when the NRC observed a fire hose being used to drain a fire header in accordance with instructions. It was determined that during this time the hose was unavailable for fire protection. This was due to a weakness in work control processes and in the instructions on the control of fire houses which has now been corrected. Had a fire occurred the alarm would have sounded and the fire brigade would have responded and provided fire hoses.
- NCV (Green)—for failure to control access to a high radiation area with dose rates greater the 1 Rem/Hour (C-C Aspect H.12 Avoid Complacency). This occurred in October 2013 when a gate in a temporary barrier placed by radiation protection specialists around radioactive materials was found ajar due to a forklift having been operated in the area to shift a concrete block. No plant personnel received additional exposure and it was determined that the temporary barrier should have required a locking gate such that inadvertent exposure could not occur. Dr. Budnitz observed and Mr. Baldwin agreed this represented a lapse in safety culture.
- NCV (Green)—for failure to effectively implement risk management actions associated with safety-related EDGs (C-C Aspect H.11 Challenge the Unknown). This event was reported in December 2013 when a licensed operator caught his foot on an EDG fuel hose and broke a fitting rendering the EDG unfit for use. At that time another EDG was returning to service from a maintenance activity and during that time power remained available from off-site sources.
- NOV (SL III and White Finding)—for failure to obtain prior approval for a change which decreased the effectiveness of the Emergency Plan. PG&E in November 2013 identified a concern, as a result of a visit to another power station, regarding instructions for communicating recommended protection actions to San Luis Obispo County with reference to protective actions in ocean areas. Instructions were deleted in 2005 which required advisement by PG&E after an accident relative to protective actions, including evacuation of boaters, required over ocean areas in the event of a release over water. This issue was addressed with the County in 2013 and the instructions were restored. Mr. Baldwin reported that requirements and processes were always in place whereby upon declaration of a general emergency, the lowest level alert that could result in a release to the environment, the U.S. Coast Guard would have automatically taken action to clear a six-mile perimeter off shore from DCPP. Federal regulations, however, required those instructions be part of the procedures and Mr. Baldwin stated the event resulted in a violation and a detailed cause analysis was performed which will be reviewed by the NRC. In response to Dr. Lam’s request, Mr. Baldwin described a White Finding as part of the NRC’s Reactor Oversight Process which grades the potential significance of an event, usually using a risk-informed perspective. A White Finding indicates a moderate safety significance. However, that determination is not risk-informed in terms of probability and is made using a deterministic criterion. Mr. Baldwin and Mr. Harbor confirmed that DCPP accepts full responsibility for this past omission and in response performed a review of all emergency planning licensing basis issues which found and resulted in correction of a number of procedural discrepancies. A report will be published soon and Dr. Budnitz confirmed the DCISC will review it when it is made available.
- NCV (Green)—for failure to provide adequate design review of EDG 2-3. This issue involving failure of a control wire that was discovered during a test run of EDG 2–3, which was installed as a sixth EDG during the mid-1990's after the installation of the other EDGs. EDG 2-3 is very similar to the other EDGs but Mr. Baldwin stated there are some differences. The control wire failed due to a cover which pushed against it. This cover was removed and the cover is not present on any of the other EDGs. The NRC determined that DCPP should have removed the cover on EDG 2-3 when it was installed. The EDGs have been reviewed for other differences and no others were identified that have the potential to cause problems.
Mr. Baldwin summarized and reviewed the inspection reports issued during the period of his report:
- Emergency Preparedness Annual Report (2014-501, 1/17/15)
- Integrated Inspection Report (2014-005, 1/29/15)
- Emergency Preparedness Inspection Report (2015-502, 2/11/15)
- Annual Assessment Letter (2014-001, 3/4/15)
- Integrated Inspection Report (2015-001, 5/5/15)
In summary, Mr. Baldwin reported all NRC performance indicators continue to meet NRC green expectations. Cross-cutting performance is strong, with no cross-cutting themes or developing themes identified.
Ms. Linda Seeley of Mothers for Peace was recognized following Mr. Baldwin’s presentation. Ms. Seeley inquired concerning an issue with loading of the dry storage casks which was recently reported. She remarked it was her understanding that these casks were to be loaded with the higher temperature fuel in the center of the cask, with lower temperature fuel placed around the perimeter and it was found that 19 of the 34 casks that have been loaded since 2009 were loaded improperly and in violation of Technical Specifications (TS).
Mr. Baldwin replied to Ms. Seeley’s remarks and stated that the TS require the fuel assemblies with the longest cooling time out of the reactor core be placed on the outside of the other fuel assemblies and this does not necessarily correlate with the lowest temperature or to the lowest heat load. However, the present TS requires the highest heat loads in the center of the casks and the lowest heat loads on the perimeter of the casks and DCPP determined that it had not complied with the TS in terms of observing the longest cooling times and ensuring the longest cooling time assemblies were on the perimeter of the casks. The licensing requirement and TS were developed in the early 2000's and additional analysis has since been performed and Mr. Baldwin observed the rest of the U.S. nuclear industry does not use the same TS basis as DCPP. Mr. Baldwin described the TS for DCPP as outdated but he confirmed the plant is required to follow its TS and a license amendment is required to change the TS. Mr. Baldwin stated that the manner of loading the casks at DCPP was in accordance with the intent of putting the highest temperature assemblies toward the center but it was not in compliance with the TS although he described the manner of loading as safe. He confirmed that DCPP will not make further cask loadings in violation of its TS and before changing to a fully compliant TS loading protocol the plant will have to process a license amendment request with the NRC. He stated that a root cause investigation is being performed on this issue.
Ms. Sherry Lewis was again recognized. She inquired whether high burn-up fuel is placed in the center of the casks.
Mr. John Geesman on behalf of the A4NR was recognized. Mr. Geesman observed the DCISC had recommended in an Annual Report that PG&E accelerate transfer of spent fuel from the spent fuel pools to dry cask and was told by PG&E that the primary constraint was the cask loading requirements. He reported the CPUC in its current PG&E General Rate Case adopted a requirement that before PG&E’s next general rate case, scheduled for fall 2015, PG&E should submit a plan to accelerate transfer of spent fuel consistent with NRC requirements and recommendations of the CEC. Mr. Geesman stated the fact that PG&E could err on this magnitude concerning the loading of spent fuel, irrespective of any safety consequences, is indicative of a problem with safety culture at DCPP and this should be a top priority for the DCISC.
Dr. Peterson observed that he has worked extensively with issues of heat transfer and thermal management and he is unsure of the logic of loading hot and cold assemblies in the center or on the perimeter of the casks and he stated he is not surprised that other plants have had their TS modified to remove similar requirements and the DCISC should commit to reviewing this issue and to asking PG&E to make a presentation at some point in the future. Dr. Peterson also stated the discussion of deliquescence is an issue worthy of review, as the temperature difference between the ambient air and the canisters can make it impossible, even with salt on the outside of the canister, to observe the condensation of salt. Dr. Peterson observed this was an important issue because, in order to induce stress corrosion cracking, deliquescence would be the most plausible mechanism by which salt could accumulate moisture and become corrosive and therefore to an understanding how the temperature of the casks evolves over time.
Mr. Harbor thanked the members of the public who spoke on the issue of cask loading and he stated DCPP and PG&E take this issue very seriously and the issue is now undergoing a root cause analysis. Mr. Harbor stated DCPP continues to work to improve safety culture and concentrates on ten core safety culture principles including problem identification and resolution and maintaining a questioning attitude. Mr. Harbor confirmed that concerning this issue the plant’s TS were not met.
Mr. Geesman was again recognized and observed that he has a great respect for a questioning attitude but representations were made by PG&E to the CPUC which were clearly premised on a fundamental misunderstanding of what the NRC requirements actually were and to some extent this culpability spreads beyond the licensee to the manufacturer. He described this matter as a very significant oversight.
Mr. Harbor requested Mr. Baldwin to continue with the next informational presentation to the DCISC.
Status of Office Seismic Safety and the Seismically Induced System Interaction Housekeeping Program.
Mr. Baldwin introduced his presentation on office seismic safety, improved seismic preparedness, and past and present improvements. He reported the Seismically Induced Systems Interaction Program (SISIP) is a program in existence since the plant was built to protect plant equipment from being affected by the actions of transient equipment in the event of an earthquake. Carts, materials, and tools that are taken into the plant to perform routine operation and maintenance when not under direct control are examples of transient equipment. If an earthquake were to occur, the SISIP functions to insure transient equipment will not move and interact with important and necessary plant equipment. This is normally done by removing the transient equipment from the plant or securing it and managing it by work control processes as well as by monthly walkdowns by housekeeping area owners. Deviations are documented in the Corrective Action Program. SISIP program owners review monthly walkdown results and findings for early signs of deviation trends and take action to alert managers to heighten their focus for low level trend concerns. Results include a cleaner plant and deviations are infrequent, minor and promptly corrected. In response to Dr. Budnitz’ inquiry Mr. Baldwin confirmed that the SISIP includes some installed, as opposed to transient, equipment such as handrails. Dr. Budnitz observed the NRC in 1980 developed generic issue A17 to address installed equipment which required a series of walkdowns to verify that installed equipment did not suffer from seismic interaction problems and he wondered why at that time the NRC did not address transient equipment as was done for transient fuel sources.
Mr. Baldwin reported the Office Seismic Safety Program is an initiative largely credited to Dr. Peterson to improve DCPP office safety in the event of an earthquake by bracing office furniture, file cabinets, book cases and storage racks. These actions are intended to protect personnel from injury and to ensure access and egress routes are not blocked by office furniture impacted by a seismic event. DCPP recently recognized additional improvement opportunities in personnel safety by sharing knowledge from the station fire chief and civil seismic engineers with plant staff. Mr. Baldwin stated the hazards are different from those addressed by the SISIP and there are some issues in the power plant affected by the Office Seismic Safety Program which were addressed in 2013 when questions were first raised by the DCISC although additional issues continue to be identified.
Mr. Baldwin stated that the Office Seismic Safety Program involves communication to station personnel of the Guidance Policy, a station-wide communication bulletin (quarterly), and identification of an annual office safety focus area. Area owners are assigned and walkdowns performed by housekeeping area managers with a tracking process established for resolution of items using the facilities management process and Corrective Action Program.
Mr. Baldwin reported all risk significant actions, such as those in the chemistry labs, were completed in 2013. Additional issues require correction by the end of July 2015. All improvements will be made by December 24, 2015. Mr. Baldwin reviewed with the Committee the improvements completed to date to improve office seismic safety including:
- Demolition of Support Building 201
- Removal of various temporary facilities
- Modernization of the Outage Coordination Center
- Modernization of 2nd, 4th and 6th floor offices
- Modernization of Security & Maintenance Services offices in Buildings 102, 116, 113
Improvements Scheduled in 2015 to Improve Office Seismic Safety include:
- Relocation of Integrated Site Services to new facility in Area 10
- Relocation of paint crew to new facilities
Mr. Baldwin displayed a photo of an office area before and after changes were made based upon the Office Seismic Safety Program and described the improvements made to enhance safety of personnel working in the area.
Dr. Lam observed that much credit for the improvements achieved by the Office Seismic Safety Program is due to Dr. Peterson and he described the program as a clear example of what the DCISC can do in contributing to reactor safety.
Mr. John Geesman of the A4NR was recognized. Mr. Geesman stated that from Mr. Baldwin’s presentation it is clear that significant deficiencies continue to exist more than one year after the DCISC made office seismic safety a priority in its Annual Report. Mr. Geesman submitted his hypothesis that a cultural problem is responsible for certain persons at DCPP having a level of denial that a real risk exists. PG&E has stated for many years that it has made sophisticated analyses of the seismic setting of DCPP but it is evident that cultural problems exist which are indicative of larger problems that affect much of PG&E’s seismic analysis of the plant site.
Ms. Linda Seeley of Mothers for Peace was recognized. Ms. Seeley inquired about an issue with the heating, ventilation and air conditioning of the plant Control Room being properly installed and connected and she wondered if that problem had been resolved. Dr. Peterson replied that this problem was addressed by DCPP.
Mr. Harbor introduced Ms. Jacquie Hinds, DCPP Quality Verification Director and stated Ms. Hinds has more than 30 years nuclear experience, holds a Bachelor of Science Degree in Chemical Engineering and has held leadership roles in the Engineering, Regulatory Services organization and in providing support to PG&E’s Chief Nuclear Officer.
Quality Verification Organization’s Perspective on Station Performance: Strengths, Top Issues, and the Quality Performance Assessment Report.
Ms. Hinds reported that since graduation from U.C. Davis she has been a resident of the local San Luis Obispo community and raised her family in the area and she continues to look forward to residing in the local area.
Ms. Hinds stated Quality Verification’s (QV) mission is to strive for excellence, identify gaps to excellence, ensure compliance with regulations and improve DCPP quality through critical and effective independent oversight. The QV organization provides a Site Status Report which identifies its top issues. The regulatory compliance role of QV stems from NRC requirements that all nuclear power plants have a Quality Assurance Plan based on Title 10 Code of Federal Regulations (CFR) Part 50 Appendix B. The DCPP Quality Assurance Plan is contained in the plant’s Final Safety Analysis Report (FSAR). In accordance with these requirements, the QV organization performs audits and conducts assessments and inspections.
Ms. Hinds reviewed with the DCISC QV’s current top three issues included in the Site Status Report which QV periodically shares with the DCISC, at Plant Performance Review meetings, and in meetings with senior plant leadership and with Mr. Ed Halpin, the Senior Vice President and Chief Nuclear Officer (SVP/CNO). These issues include:
- Equipment Reliability
- Long Term Preventive Maintenance Strategy
- Protected Equipment Postings
Ms. Hinds stated equipment reliability has challenged plant operations since the end of 2014 as demonstrated by forced loss rate and unplanned entries into Technical Specifications (TS). Identified Gaps included the lack of an integrated plan as a framework for improvement, plans lacking granularity to ensure appropriate actions were taken, no established governance process to ensure accountability, and a lack of alignment on actions. She reported on the current state of equipment reliability as including creation of the Equipment Reliability Initiative based upon integrated plans with detailed actions, director responsibility for ensuring focused progress in addressing equipment reliability, a governance process established that ensures frequent review of results and actions, and a communication strategy to raise awareness and share results. She observed that plant performance in minimizing issues of equipment reliability during the first six months of 2015 shows improvement and is reflected in the NRC performance indicators and Ms. Hinds stated equipment reliability is expected to be removed from the QV top issues list by the end of 2015.
Concerning the Long Term Preventive Maintenance Strategy Ms. Hinds stated that station deferral of critical preventive maintenance tasks was high compared to the industry. The issues were reviewed at Plant Performance Review meetings. This issue was identified by the station in a mid-cycle assessment and QV issued a Finding. Identified gaps include deferral of critical tasks not being consistent with industry best practices and the need for a long term strategic plan to optimize the Preventive Maintenance Program. The current status includes no deferrals of preventive maintenance tasks for the upcoming refueling outage, completion of benchmarking, and development of an action plan to improve the Preventive Maintenance Program.
Regarding postings for protected equipment Ms. Hinds observed that protected equipment posting requirements are complex and challenging to implement. Protected equipment is equipment for which there is a need to raise awareness to employees when equipment similar to it may be taken out of service and there is a heightened need to protect remaining operable equipment. An identified gap at DCPP was revealed by QV’s observations during the last refueling outage that requirements were contained in several procedures, making it difficult to implement and the issue was not being addressed as timely as QV required. To address the issue procedures have been revised and brought together with input from the operating crews. Observations will be made during the next refueling outage to provide feedback on the implementation and effectiveness of the revised procedure.
Ms. Hinds stated that the next Site Status Report will not include protected equipment posting or long term preventive maintenance strategy as top issues. In summarizing her presentation, Ms. Hinds stated DCPP continues to operate safely, the Quality Assurance Plan is effectively implemented, and DCPP remains responsive to issues raised by QV and to issues raised outside of QV which she terms as a good cultural trait.
In response to Dr. Lam’s inquiry Ms. Hinds stated she reports directly to the SVP/CNO on not less than a monthly basis to review issues identified by QV and she stated she believes she has Mr. Halpin’s full support although she has not had to rely on Mr. Halpin as she also has the full cooperation of her peers and the other directors at DCPP. Also by raising awareness and providing facts on the issues and using the tools QV has available to it, the response has been good. In response to a question from Consultant Linnen, Ms. Hinds stated that she was unaware of any case where obsolescence of equipment has been an issue with the equipment’s reliability. Mr. Harbor stated that DCPP addresses issues of obsolescence through its capital enhancement program and through reviews by engineering and obtains appropriate replacements when necessary for design changes through its supply chain. In response to Consultant Wardell’s inquiry Ms. Hinds confirmed there is an escalation program available to her in her role as QV Director and that she used the escalation program for one issue last year. In response to Consultant Linnen’s inquiry as to what degree equipment reliability issues might be tied to issues of rework Ms. Hinds stated that she would need to review and would provide a specific response on another occasion.
Ms. Sherry Lewis of Mothers for Peace was recognized and asked for an explanation of the meaning of an independent oversight function. Dr. Budnitz replied that NRC regulations require every plant to have a Quality Assurance office which reports directly to the plant’s senior officer and in that function the Quality Assurance function is independent of the line organizations.
Mr. Harbor introduced Mr. Scott Maze to make the next informational presentation and stated Mr. Maze is the Supervisor of the DCPP Fukushima Project and has been in the nuclear industry for more than 25 years, holds a Bachelor of Science Degree in Civil Engineering and is a registered Professional Engineer.
Results of Post-Fukushima Study of DCPP External Flooding Hazards
Mr. Maze stated he is the engineering supervisor for the Fukushima Project and was assigned the task of performing the flooding reanalysis. He remarked he, like Ms. Hinds, is a graduate of U.C. Davis and he has resided in the local area with his family since his graduation 26 years ago. He reported his presentation would address a new and extensive flooding reevaluation performed at the NRC’s direction which continues to show the plant can safely withstand tsunamis and flooding. PG&E’s tsunami hazard update involved the use of site-specific information, the latest models, techniques and methodologies and independent expertise. The results of this study show the current tsunami design level for Diablo Canyon is still appropriate and provides for safety at the plant. He reported that one area identified for further assessment is ensuring the plant is fully prepared for an extremely rare, but potentially intense localized storm. PG&E has already implemented additional measures to ensure DCPP is prepared, such as pre-staging sand bags during such a storm, and is investigating additional measures to curb water away from these areas. He stated his presentation would cover:
- NRC Correspondence
- NRC Guidance and Methodology
- Overview of Analyses
- Probable Max. Precipitation (PMP)
- Probable Max. Flood (PMF)
- Local Intense Precipitation (LIP)
- Interim Actions
- Storm Wave
Mr. Maze reviewed the NRC correspondence issued regarding the flooding reanalysis which included the NRC’s March 12, 2012 Letter requesting information issued by the NRC pursuant to 10 CFR 50.54(f) requiring that DCPP reevaluate site seismic and flooding hazards using updated flooding information and present-day regulatory guidance and methodologies. PG&E’s Letter DCL-12-059 was the company’s 90-Day Response to Flooding Aspects of 10 CFR 50.54(f). Per the NRC’s direction, plants were to submit flooding hazards reevaluation to the NRC by March 12, 2015, for which PG&E submitted its Letter DCL-15-0345 on March 11, 2015 as its final report to the NRC, and will submit new evaluations to address additional NRC- required post Fukushima requirements by March 2017. Dr. Budnitz stated that he served as a consultant to the NRC staff issuance of guidance concerning flooding reanalysis and as a consultant to the NRC on reviewing submittals from nuclear power plants but Dr. Budnitz has recused himself in that role from consideration of anything having to do with DCPP.
Mr. Maze reported NRC guidance and methodology requires new evaluations to consider beyond design basis events for seismic and flooding; that is, events that are beyond what DCPP’s current license requires these issues need to be treated as if the plant were being built at the present time using current codes, methodology and current standards. In essence a reevaluation is performed using NUREG 0800 which is the standard review plan for building a new nuclear power plant.
Mr. Maze described and discussed an overview of calculations required by the analyses:
- Flooding Hazard Analyses
- PMP: Computes all-season general storm probable maximum precipitation (PMP), seasonal general storm PMP, and local storm PMP values using California information.
- Probable maximum flood (PMF): Calculates PMF values along Diablo Creek through the DCPP site (based on PMP results) coincident with wind/wave activity, i.e., maximum Water Surface Elevations (WSE).
- Local Intense Precipitation (LIP): A “Microburst” (6-hr) PMP. Calculates maximum LIP WSE over the entire site drainage basin.
- Tsunami/Ocean Analyses
- Tsunami: Calculate distant and near source tsunamis (both seismic & offshore landslide) with updated hydrostatic & hydrodynamic forces, debris and water-borne projectiles, and sedimentation/erosion.
- Storm Surge: Performs an evaluation of local wave data to develop storm surge and storm wave parameters.
Mr. Maze confirmed Dr. Budnitz’ observation that flooding and tsunami hazard analyses were done when the plant was first licensed, and the requirement from the NRC was that these analyses be updated based upon modern understanding which provides more detail. In response to Dr. Lam, Mr. Maze confirmed the analyses are beyond design licensing requirements as they are not within the plant’s current license framework. Dr. Budnitz observed that for many plants there has not been a need to revisit these issues unless a dam was constructed or a levee built in the area.
Mr. Maze provided a site overview of DCPP including the 500 kV switchyard under which Diablo Creek flows through a ten foot culvert under 230 kV and 500 kV lines. He reviewed the PMP analysis and stated it was computed for all-season general storm PMP, seasonal general storm PMP, and local storm PMP values. DCPP has a drainage basis of approximately 5.2 square miles which he reported is much less than some plants located in the mid-west that have drainage basis on 1,000,000 square miles. This data was then utilized as input to the PMF analysis. The data utilized Hydrometerological Reports (HMRs) 58 & 59 published by the National Ocean and Atmospheric Administration (NOAA).
Mr. Maze reported the PMF analysis was calculated using PMF values, i.e., maximum water surface elevation along Diablo Creek through the DCPP site and conservatively assumed 100 percent blockage of all storm drains. Additionally the PMF analysis was evaluated for wind waves. The analysis found WSE and flow rates are less than those in the plant’s current license due to a change in the HMRs and the availability of more sophisticated computer modeling methods and there is no impact from the reanalysis to safety-related plant systems, structures or components (SSCs). In response to Dr. Budnitz’ inquiry, Mr. Maze confirmed that there is increased confidence in the data as it is his belief that HMRs 58 and 59 are conservative and DCPP was allowed to, but in fact did not, utilize a site-specific PMP which includes more detail, and he noted that local weather conditions within an area of California can be very different from another area.
Mr. Maze discussed the LIP which he stated involves analysis of extremely rare but potentially intense local storm activity directly over the plant site, representing 5.9 inches of rainfall in a 6-hour period with 2 ½ inches of rain falling within the first 15 minute period. He reported new techniques and software provide detailed water levels around the site and utilize a site-specific PMP and more recent storm data and area-specific data than in HMRs 58 & 59. He reported this effort was not first-of-a-kind and represented a typical industry approach. The return period for the LIP analysis was one event every 129,000,000 years. Mr. Maze reported the most rain ever received at DCPP in a 24-hour period was 8.5 inches in 1995.
For the LIP analysis Mr. Maze reported walkdowns were performed to identify potential entry points to safety-related structures and to determine maximum WSE resulting from the effects of LIP at the DCPP power block area. The analysis assumed all drainage systems non-functional and identified and implemented actions that would be taken to mitigate inundation at potential entry points. DCPP did not use the method employed by some plants to assert that the LIP analysis was bounded by the plant’s internal pipe break analyses. LIP mitigation actions included interim actions to pre-stage sandbags, a process in place for the shift foreman to monitor weather forecasting, warning, and alert systems, and evaluation of sandbags to withstand the LIP event in which they will be needed. Procedures were revised to direct installation, including appropriate triggers to activate response, and training was conducted for Operations and necessary personnel. Reasonable simulations were performed per the Nuclear Energy Institute’s guidance to ensure the sandbags can be installed in the planned time frame.
Mr. Maze reported actions for long-term resolution include and will be addressed in an Integrated Assessment Report due to the NRC in March 2017, by investigation of permanent modifications to prevent effects of LIP, and by evaluating the result of inundation and other potential mitigating actions.
Mr. Maze reported that analysis has been performed for internal pipe break events that would flood a building and that a time-dependent study could be done based upon and compared to those analyses. In response to Dr. Peterson’s comment, Mr. Maze confirmed these issues also involve the FLEX response, and flooding is an issue that is dealt with by a FLEX response upon the occurrence of the loss of the emergency diesel generators and the loss of all off-site AC power which he reported is the starting point for a FLEX-based response. In response to Dr. Budnitz observation, Mr. Maze confirmed the reanalysis benefited from the use of better data.
Dr. Budnitz observed the American Nuclear Society (ANS) developed Standard 2.8 which governs how this type of analysis is done, and Mr. Maze confirmed DCPP was initially following the ANS standard as part of the Fukushima Near Term Task Force efforts with the NEI. Dr. Budnitz reported that he is a member of the ANS standards board and within the next six to twelve months the ANS is expected to issue a new standard, and Mr. Maze observed and Dr. Budnitz confirmed that the new ANS standard will be factored into the responses required to the NRC’s tier two and tier three directives.
Dr. Budnitz observed that for many sites in other parts of the country flooding is the principal hazard but for a site such as DCPP seismic is the principal hazard to be addressed. Dr. Budnitz reported the new ANS standard takes a probabilistic approach to the various LIP phenomena and represents a more inclusive approach.
Dr. Peterson inquired about the impact of potential highly intense precipitation events causing flooding and the resulting impact on emergency access and egress, and he observed that such flash flooding can disable access and is a very serious event. Mr. Maze stated the analysis work was done solely to look at the protection of safety-related SSCs to verify that the safe shut down capacity of the plant was maintained and the impact of a flash flooding scenario likely falls within the purview of the Emergency Planning organization. Mr. Harbor confirmed Mr. Maze’s observation and stated DCPP has a stranded plant procedure along with its FLEX strategies to address the conditions referred to by Dr. Peterson. Dr. Peterson commented that there is benefit in the process to review more broadly for hazards items and issues that, while they may not impact plant safety, they may be important for public health and safety and may therefore be identified. Mr. Maze agreed and commented that this is part of the FLEX initiative.
In response to Dr. Budnitz question Mr. Maze stated the geographical area for the LIP is a one-square mile moving storm and the PMP is also a local event of 52.2 miles in area. In response to Consultant Linnen’s inquiry about extending the scale of an event, Dr. Budnitz observed it is not the probability of an event during any one year but rather the size of the watershed, which remains constant, that is important. Dr. Budnitz remarked the NRC’s prescribed guidance provides how the analysis is to be done at a certain level of precision but there is a certain inaccuracy in the data. Mr. Maze replied that the data from NOAA is accurate as to the inputs from the HMRs. In response to Dr. Budnitz’ question Mr. Maze stated that it was possible such large precipitation events would result in the disruption of offsite power.
Concluding his presentation, Mr. Maze stated the flooding re analysis shows DCPP is safe and revealed no issues with PMP and PMF. One area was identified for mitigation, that being an extremely rare localized storm event and mitigating measures are in place to protect DCPP safety-related structures, systems, and components. Dr. Budnitz remarked that PG&E’s submittal to the NRC will be reviewed by staff and either more information and questions will remain to be addressed or the submittal will be accepted by the NRC. Mr. Maze stated DCPP has already supplied additional data requested by the NRC and expects to receive a response from the NRC by 2016.
Ms. Linda Seeley of Mothers for Peace was recognized. Ms. Seeley stated she wondered why such severe weather events, with a frequency of every 129,000,000 years, were used for the reanalysis rather than a continuous rain event lasting several days. She also inquired as to how high the water level would be at the plant from these events. Dr. Budnitz observed that the batteries at the plant would be no less than 30 feet above the highest water levels projected and that this was an important fact. Ms. Seeley closed her remarks by stating that due to the presence of 13 earthquake faults in the area a nuclear power plant would not be allowed to be built today at the site of DCPP.
Dr. Gene Nelson was recognized and stated he serves on the physical sciences faculty at Cuesta College. Dr. Nelson stated that having an earthquake fault in proximity to a structure does not mean that the fault poses a risk to the structure and he stated Ms. Seeley’s comments were alarmist in nature. Dr. Nelson encouraged the DCISC to listen to scientific and engineering analysis instead of alarmist comments.
Mr. Maze and Dr. Budnitz confirmed Dr. Peterson’s observation that the reanalysis includes certain assumptions concerning rainfall which are required by the codes including the assumption that the ground is fully saturated and that 100 percent of the rainfall impacts the site in terms of runoff. In response to Dr. Peterson’s question about the effect of the storms of 1995, Mr. Maze stated he was present and on-site at DCPP during 1995 and has no recollection of water ever entering the plant nor is there any evidence that it did so although this evidence is anecdotal as there is no record of the water levels reached during1995. In response to Dr. Budnitz’ comment about the NOAA data and the effect of intense precipitation Mr. Maze confirmed that intense precipitation for short periods can produce more flooding than a rain event lasting several days as there is more runoff of water. Mr. Maze observed that the concern with a long rain event is with Diablo Creek and the re analysis establishes there is at least eight feet of margin between the creek and plant levels including accounting for wind-driven waves.
XV Adjourn Afternoon Meeting
The Chair adjourned the afternoon meeting of the Committee at 4:35 P.M.
XVI Reconvene for Evening Meeting
Dr. Peterson convened the evening meeting of the DCISC at 5:30 P.M. He introduced the other Members and welcomed members of the public present in the audience and those following the meeting by the streaming video available through a link on the Committee’s website at www.dcisc.org or at www.slospan.org
XVII Committee Member Comments
There were no comments by Committee members at this time.
XVIII Public Comments and Communications
Dr. Peterson inquired whether any member of the public wished to comment or address the Committee on matters not appearing on its agenda for this meeting. There were no comments by members of the public at this time. There was no response to Dr. Peterson’s invitation.
XIX Information Items Before the Committee (Cont’d.)
The Chair requested Mr. Cary Harbor, Director of Compliance, Alliance and Risk at DCPP, to continue with the informational presentations by PG&E. Mr. Harbor introduced Mr. Scott Maze to continue with the informational presentations.
Presentation on Results of PG&E’s Tsunami Studies
Mr. Maze stated he is the supervising engineer on the DCPP Fukushima Project and has been in the nuclear industry with PG&E for 26 years and resides in the local San Luis Obispo area. Mr. Maze stated that along with personal and industrial safety, nuclear safety is a key priority for DCPP. PG&E performed an extensive flooding reevaluation of DCPP, at the NRC’s direction, that continues to show the plant can safely withstand tsunamis and flooding. This tsunami hazard update involved the use of site-specific information, off shore bathymetry data, the latest models, techniques and methodologies, and independent expertise. The results of this study show the current tsunami design level for Diablo Canyon is still appropriate and provides for safety at the plant.
Mr. Maze reviewed the NRC guidance and methodology stating the overall approach, similar to the flooding analysis he discussed earlier in this public meeting, was to reevaluate seismic and tsunami hazards using updated seismic and flooding hazard information and present-day regulatory guidance and methodologies as if the plant were a new plant to be reviewed under the following:
- NRC Regulation (NUREG) 0800, the Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants;
- Regulatory Guide 1.70: Standard Format and Content of Safety Analysis Reports for Nuclear Power Plants;
- Regulatory Guide 1.59: Design Basis Floods for Nuclear Power Plants NUREG/CR-7046:
- Design-Basis Flood Estimation for Site Characterization at Nuclear Power Plants in the U.S.;
- NUREG/CR-6966: Tsunami Hazard Assessment at Nuclear Power Plant Sites in the United States of America—Final Report; and JLD-ISG-2012-06: Guidance for Performing a Tsunami, Surge, and Seiche Flooding Safety Analysis.
Dr. Budnitz observed the “JLD” designation stands for the Japan Lessons learned Directorate and “ISG” stands for Interim Staff Guidance and that he served as a consultant to the NRC staff for JLD-ISG 2012-06. Dr. Budnitz remarked that his recommendation, which was not adopted, would have required a probabilistic analysis by each nuclear power plant.
Mr. Maze provided an overview of the tsunami analysis which included selecting seismic sources for tsunamis located near and far from the plant site, analyzing submarine landslides and considering insights from the draft Sewell study of 2003. Mr. Maze observed there is a need to consider submarine landslides and for more detailed modeling in these efforts. Dr. Budnitz reported that the DCISC has recently engaged Dr. Robert T. Sewell as a consultant to perform additional review of the tsunami hazard at DCPP and its environs and the Committee expects that Dr. Sewell may make a public presentation at the DCISC’s public meeting in October 20–21, 2015.
Mr. Maze reported distant and near-source seismically generated tsunamis were selected using the Final Safety Analysis Report (FSAR), historical tide gauge data to compare against historical tsunamis, current geoscience activities for Recommendation 2.1 Seismic Reanalysis, and recent California studies, including the USGS study (SAFRR, 2013) and previous PG&E studies (2006-2010).
The tsunami analysis of submarine mass failure (SMF) included analyzing submarine landslides using the detailed bathymetry effort undertaken in 2006 for PG&E’s report to determine sea floor topography, detailed geophysics and geology analysis performed to characterize potential slides which formed input for current modeling, and bounding landslide characteristics from the Big Sur Slide representing a slide along the Santa Lucia Escarpment, and the Goleta Slide representing a slide in the Santa Maria Slope Break. In response to Dr. Peterson’s inquiry, Mr. Maze stated DCPP has up to one meter resolution for bathymetry data around the plant site and for areas of the sea floor located further out from the coast. NOAA data from 2006 was used.
Mr. Maze displayed and discussed a map depicting historically recorded tsunami run-ups and various modeled results with the proxies for the Big Sur and Goleta Slides shown on the map, with the Big Sur Slide proxy, a slide of approximately 5 kilometers by 3 kilometers in size, placed in proximity to DCPP which produced a postulated 7.15 meter height for a tsunami based on the Big Sur Slide. The Goleta Slide proxy, based on a proxy of three separate slides in the Goleta area which in total was smaller in size than the Big Sur Slide, was placed in very close proximity to the plant site. Mr. Brendan Dooher reported the Goleta Slide data includes information from the Gaviota mudslide of 1812. This Goleta Slide proxy produced a postulated run-up from a tsunami at between 2 and 3 meters in height which Mr. Dooher remarked was in keeping with historical records. In response to Dr. Lam’s inquiry Mr. Maze responded the size of the proxy slides was selected based on geologic review of bathymetry data and he confirmed that slides of other sizes might have potentially been selected by other reviewers. Mr. Maze stated the slides selected were the largest possible slides postulated to ever occur along the coastline of California and the model is sensitive to the size of the selection of sources for run-up and volume, or as Dr. Budnitz remarked that the model is therefore sensitive to a differing assignments of parameters in a probabilistic sense. Dr. Budnitz reported that along with Consultant Linnen he received a presentation from PG&E and Dr. Stephan Grilli on this topic during a fact-finding visit to PG&E’s San Francisco headquarters in March 2015.
Mr. Maze reported the tsunami analysis approach included creating a 3-D hydrodynamic model for bottom motion of the sea floor, analyzing tsunami source propagation using NRC-recognized programs NHWAVE and FUNWAVE, and participation by a leading independent expert, Dr. Grilli of University of Rhode Island. This method was benchmarked for Diablo Canyon with data from the 2011 Tohoku event in Japan which closely matched observed effects and the model also evaluated seismically initiated submarine landslides including an event on the Hosgri Fault, including a potentially degraded breakwater condition. The wave run-up data was then input to new analyses for hydrostatic and hydrodynamic forces, debris, water-borne projectiles, and sedimentation and erosion.
Mr. Maze displayed a graph and cutaway depiction of the tsunami analysis results which showed the configuration at an assumed high tide, with a long-term sea level rise factored in, which resulted in a maximum run-up at the DCPP Intake structure of 29.9 feet above mean sea level elevation. Mr. Maze stated that it was important to verify that the snorkels for the Auxiliary Saltwater System (ASW), which is a safety-related system, remain protected. The data was also checked for erosion issues for the protective installations over the ASW piping, such as concrete pads and the gabion mattress, to verify the ASW System remains functional. Dr. Peterson observed that a tsunami would also be expected to deposit debris and this debris disabled many of the plants on the Japanese coast during the March 2011 tsunami event resulting in loss of ASW for an extended period of days. Mr. Maze confirmed Dr. Peterson’s observation and reported there was a study of Diablo Cove performed which looked at bathymetry data down to one meter as well as the rocks and boulders and the breakwater itself as potentially becoming part of the debris. Dr. Peterson observed that the portable pumps for the ASW System have yet to be fully tested and therefore it is an open issue as to how long that portable system would function before its suction plugs with debris. Mr. Maze stated sedimentation and filtration screening is being included in the design of the FLEX ASW Systems and Dr. Peterson observed there is a need to get the ASW pumps tested under realistic conditions as soon as possible. Dr. Budnitz observed that a tsunami event results in an initial drawdown of water and when that drawdown occurs there are huge hydrodynamic forces created and those forces return and impact the shoreline when a tsunami strikes the coast. Dr. Budnitz stated that for a tsunami event near Alaska or Chile there would very likely be adequate warning but for a near shore tsunami there would be no or little practical warning to shut down the plant.
Mr. Maze reported the results of the analysis included no adverse impact to any safety related SSCs, water levels two feet lower than licensing basis levels, and no adverse impacts from run-up to the safety related ASW System. The hydrostatic/dynamic loading, and projectile calculations showed lower values than those evaluated in the licensing basis. The drawdown effect would have no adverse impacts to safety related ASW systems Dr. Lam remarked the study by Dr. Sewell indicated very different magnitudes for postulated tsunamis than Mr. Maze discussed in his presentation and he inquired what PG&E had done differently than Dr. Sewell. Mr. Maze replied stating that PG&E used more recent and updated modeling data in its analysis and he remarked the Sewell report used very large sources for the input on the size of the submarine landslides.
Mr. Maze stated the Storm Wave Analysis used the area from Monterey to Point Arguello and was modeled using current methodology and detailed bathymetry. The results included Intake Cove water levels lower than tsunami water levels and indicated that the storm waves are bounded by the tsunami analysis.
In summarizing his presentation Mr. Maze reported the new and extensive flooding reevaluation performed at the NRC’s direction continued to show the plant can safely withstand tsunamis and flooding. PG&E’s tsunami hazard update involved the use of site-specific information and the latest models, techniques, methodologies and input from an independent expert. The results of this study show the current tsunami design level for Diablo Canyon is still appropriate and provides for safety at the plant.
In response to Dr. Budnitz inquiry concerning how probable a tsunami of the magnitude described by Mr. Maze might be, Mr. Maze replied that the analysis utilized a much more deterministic approach and he did not believe there was sufficient data available, as there is really no information on an offshore tsunami in the area that is known to have occurred, to obtain a realistic probabilistic estimate. PG&E’s analysis used run-up data which were assumed to have occurred due to submarine landslides. Dr. Budnitz stated that even so, and as there is some albeit limited data available, the PG&E team should as a matter of principle consider an estimate or best judgment of its state of knowledge of what the probability is per year even with necessarily wide uncertainty bands, akin to the center-body-range concept used with SSHAC methodology. PG&E Nuclear Projects Director for DCPP, Mr. Jearl Strickland, observed that it is a somewhat different situation from that employed by SSHAC because proxies are used but he stated DCPP will take the challenge to go back and look at how the data might be extrapolated from proxies even though no discrete evidence exists of similar type landslides occurring along the coast within the proximity to DCPP used for the present analyses. Dr. Budnitz observed that the result might be data on a level of uncertainty for something half the size which is more likely although not so extreme and this could be valuable insight. Dr. Peterson commented that the DCISC’s principal interest would be in any landslide-induced tsunami which might have the potential to exceed a run-up of 85 feet and potentially cause station blackout and use of FLEX. Dr. Peterson remarked the United States Geological Survey (USGS) has conducted studies to identify paleo geologic evidence of previous tsunamis in the local area and a tsunami exceeding 85 feet would be likely to leave such evidence as it would be a catastrophic event, exceeding the tsunami at Fukushima by a factor of two. If such an event were to have a return frequency of concern then such evidence should be available and the USGs’ work should be followed very closely. Dr. Budnitz remarked that in such an effort cycles of glaciation and inter glaciation must be considered and Dr. Peterson observed that the principal threat of interest would have likely occurred during inter glaciation periods and posing a return frequency of less than one million years, there should be some evidence and it would be worthwhile to check. Dr. Budnitz cautioned that the scientific community should be careful about analogs in time that would be useful to apply to the current tsunami analyses. Dr. Peterson stated it was his assumption that the amount of sediment which would need to be accumulated to generate a tsunami exceeding 85 feet would have to be accumulated over many cycles and the risk and number of cycles required would be comparable to what it is during the current glaciation cycle.
Dr. Lam suggested that DCPP consider making a point-by-point comparison of the results of its present analyses with those from Dr. Sewell’s 2003 draft study in order to educate members of the public on the differences. Mr. Maze stated he was not prepared to undertake that effort during this presentation and that he looks forward to reviewing the report from Dr. Sewell which has been commissioned by the DCISC.
Mr. John Geesman on behalf of the A4NR was recognized. Mr. Geesman remarked that Dr. Budnitz’ point concerning a request for a probabilistic estimate based upon the result of PG&E’s tsunami analyses called to mind Dr. Budnitz comment about the uncertainties of the 129,000,000 year estimate offered for the flooding analyses and a recent estimate concerning financial markets by a noted probabilist in the range of one in three billion which was widely regarded as rhetorical nonsense.
Dr. Gene Nelson, who serves on the Cuesta College physical sciences faculty, was recognized. Dr. Nelson remarked he was aware of recent concerns focused upon a tsunami related to transpressional subsurface zones offshore from areas near Los Angeles but bathymetric studies were not completed due to lack of federal funding. He remarked that a technique in assessing paleo geologic evidence for tsunamis is to inspect in shore lagoons for unusual sediments. He stated a preliminary calculation on the odds of a large asteroid striking close enough to DCPP to cause a large tsunami from the impact found that the annual risk was 10 -11,.
Ms. Linda Seeley of Mothers for Peace was recognized. Ms. Seeley inquired why for the evaluation of a tsunami on DCPP the analyses were not done using a joint rupture scenario involving the Hosgri and Shoreline Faults and she stated this seemed like cherry picking the analysis to ensure the results work to the advantage of PG&E and DCPP. She also inquired whether the status of the Sewell study would be changed from “Draft” to “Final.” and remarked that while the earth is going through the cycles of glaciation described by Drs. Budnitz and Peterson, nuclear waste would still be present at the site of DCPP.
Ms. Sherry Lewis of Mothers for Peace was recognized. Ms. Lewis stated she did not understand the map used by Mr. Maze and would like to see a version of the cutaway depiction combined with the map. Ms. Lewis inquired and Dr. Budnitz confirmed that use of the term run-up describes the height reached by water as it moves inland after a tsunami wave strikes the coast and with reference to the Goleta proxy discussed by Mr. Maze that height would be 26-27 feet. Ms. Lewis stated she is not a proponent of the probabilistic methodology. Dr. Budnitz stated his comment was simply to ask PG&E to explain their state of knowledge and Ms. Lewis remarked her concern was that even with such limited knowledge as described by Dr. Budnitz, that information might be used for decision making.
Ms. Jane Swanson, a spokesperson along with Ms. Seeley for Mothers for Peace, was recognized. Ms. Swanson read from an abstract of a paper presented to the Association of Environmental and Engineering Geologists on July 26, 2010, by Eugene LeBlanc which discussed an earthquake which occurred near Japan in 1907 during high tide on the U.S. west coast and which resulted in a 100 foot tsunami which damaged a pier in Ventura, CA and the local Avila Oil Port pier as reported in the San Luis Obispo Tribune. Ms. Swanson also requested that PG&E consider using other than blue colored text for its slides to make them easier to read. Dr. Peterson observed that there are binders available in the meeting room to the public with copies of the power points used for the PG&E presentations to the DCISC.
Dr. Budnitz responded to Mr. Geesman’s comment and stated he does not believe the 129,000,000 year number has any significance beyond the first significant figure and he stated he does not believe PG&E places a different level of confidence in that number. He observed PG&E is using a methodology prescribed by the NRC but in Dr. Budnitz’ view the underlying data does not have the necessary precision and he stated he is sure PG&E would also agree. Dr. Budnitz commented in response to Dr. Nelson’s statement regarding an asteroid strike in the vicinity of DCPP that he found the only relevance to be that it is possible to calculate very, very, low probabilities. In response to Ms. Seeley, Dr. Budnitz replied that the Sewell study was submitted in draft to the NRC who refused to publish it and he believes that on that basis Dr. Sewell considers it to be complete and when Dr. Sewell makes his presentation to the DCISC and the public we may learn the basis on which he selected the large sources he chose for that study.
Dr. Lam commented the DCISC has been informed that Dr. Sewell is currently employed as a consultant for compensation by PG&E for work on a project entirely different that the work he did for the NRC in 2003 on the tsunami hazard in the vicinity of DCPP and from his current engagement by the DCISC. Dr. Sewell has provided his assurance that he can and will remain impartial and not be influenced by any work for PG&E. Dr. Lam stated that if there is historical data on a tsunami with a magnitude of 100 feet having occurred in the local area the DCISC needs to investigate and verify that information. Dr. Budnitz stated that PG&E considered the historical evidence referred to by Ms. Swanson and the description of the event Ms. Swanson referred to has not been found to be accurate. Dr. Peterson stated the DCISC will follow up on this issue to better understand that specific event.
In response to Dr. Peterson’s invitation, Mr. Maze reported the geoscience activities undertaken in response to Near Term Task Force Recommendation 2.1 concerning the seismic reanalysis were undertaken with regard to linkage between the Shoreline and Hosgri Faults and a joint rupture of the Shoreline and Hosgri Faults was evaluated concerning a tsunami, but because both faults are characterized as strike-slip faults there is not much potential that they might produce a tsunami and the greater potential for maximum run-ups at DCPP comes from a submarine landslide. In response to Dr. Lam’s request, Mr. Maze reported that PG&E has been unable to find a record of an earthquake in Japan in 1907 which produced a tsunami and that the report and record Ms. Swanson referred to has been basically invalidated and he confirmed it was assessed in conjunction with PG&E’s analysis work. Dr. Peterson stated it would be good for the Committee to understand more about this specific record and Ms. Swanson promised to provide information and photographs to the DCISC concerning this event.
Mr. Maze stated PG&E is following a deterministic process as required by NRC regulatory guidance and has attempted to determine the maximum tsunami or the maximum landslide levels using both the Big Sur and Goleta actual slide events as proxies. Both those locations had different lobes of slides which were believed to have slid at different times as much as 2,000 years apart. All three lobes were conservatively combined and a margin was added as a safety factor and the slide location was then placed by the models to be directly in front of DCPP where it could do the most damage.
Dr. Gene Nelson was recognized and stated that his comments he made will be included in the record of the April 28, 2015, meeting between the NRC and PG&E during which he stated he serves as government liaison for Californians for Green Nuclear Power and it is his belief that DCPP has favorable site conditions producing attenuation or dissipation of earthquake energy over relatively short distances and therefore primary earthquake forces at DCPP are dominated by nearby earthquake forces, including a small section of earthquake rupture closest to the plant. It is Dr. Nelson’s belief that, based upon information presented at the April 28 meeting and in view of the overall plant ruggedness and the seismic hazard insights discussed, DCPP will continue to operate safely with generous safety margins during anticipated earthquakes. He stated he would provide copies of his remarks to the DCISC.
Mr. Harbor introduced Dr. Norm Abrahamson and reported Dr. Abrahamson has a Ph.D. in Geophysics and has worked in the nuclear industry evaluating seismic activities for more than thirty years. Dr. Abrahamson is also an adjunct professor at U.C. Berkeley and U.C. Davis in the field of seismic hazard analysis.
Presentation on PG&E’s Seismic Studies
Dr. Abrahamson reported during his presentation he would summarize information presented at the NRC’s public meeting on April 28, 2015, including new issues in source characterization, ground motion studies, seismic hazard results, site response including work with the partially non ergodic approach, interim evaluations, and actions moving forward to reduce uncertainties in seismic hazard. Dr. Abrahamson stated with reference to the Senior Seismic Hazard Analysis Committee (SSHAC), the committee was formed in the 1990's to provide guidelines and a set of procedures or approaches for estimating seismic hazard but the committee no longer exists as a body and references to “SSHAC” are therefore to the implementation of the process proposed by that committee.
Dr. Abrahamson displayed a map of the California coastline in the vicinity of DCPP which showed its tectonic setting including the Hosgri Fault which he described as the main offshore fault controlling the strike-slip horizontal motion producing seismic hazard for DCPP. He stated the other tectonic feature controlling the seismic hazard at DCPP is the uplift of the Irish Hills and this effect can be measured. Dr. Abrahamson stated the uplift of the Irish Hills is generally caused by thrust faults on one side or the other or on both sides of the Irish Hills. He commented any tectonic model must be consistent with causing or explaining the right lateral strike-slip behavior of the Hosgri Fault and the uplift of the Irish Hills.
Dr. Abrahamson reported the SSHAC procedures provide a set of guidelines focused on capturing the state of knowledge, in a center, body, range configuration, the resulting uncertainty, and determination of the limitations of the current state of the science. Dr. Abrahamson described the three SSHAC workshops held recently to evaluate in the first workshop the data models and methods available, in the second workshop to have the models reviewed and be explained by their proponents and to ask questions, and in the third workshop to review evaluations of the alternative models including their credibility and the impact on the hazards to focus the evaluation on the issues that matter to safety at DCPP. He provided lists of the resource and proponent experts for the source characterization workshops and those involved with the ground motion workshops.
Dr. Abrahamson reviewed the highlights of what he termed as new in the source characterization models which include a large set of geophysical data collected as part of the AB 1632 work. This includes off shore seismic data, on shore seismic data and updated geologic mapping. On shore reflection data was evaluated by the USGS and off shore bathymetry, out to the Hosgri Fault, was collected in 2009–2010 time period. Dr. Abrahamson commented that many of the submarine landslides on which the Committee received information during Mr. Maze’s presentation are located farther offshore on the continental shelf and that this area was not covered in the detailed survey. Geodetic global positioning system (GPS) data was updated which shows short term deformation going on over tens of years to determine and assess consistency with geologic estimates. Dr. Abrahamson stated geodetic data is more difficult to acquire for slow moving faults such as the Shoreline Fault which take decades to move due to its very low slip rate.
Dr. Abrahamson stated for all of California there is a new seismic source characterization model developed by the USGS, the California Geological Survey, and the Southern California Earthquake Center, termed UCERF3, which is a model of earthquake recurrence for sizes, locations and rates of earthquakes for the entire state which was available and incorporated extensively into PG&E’s seismic source characterization model for DCPP. There was also a new approach used to model slip rates on the Hosgri Fault, to identify rupture sources, that is how do multiple fault segments break together in earthquakes and how often does that happen? The fault geometry model correlated geometric uncertainty. In response to Consultant Linnen’s inquiry, Dr. Abrahamson stated observed data was used as an input to the model which was acquired from around the world where multiple earthquakes occur at a site to review how much the slip varies, as slip is related to magnitude this can reveal how much the magnitudes can vary. Dr. Budnitz observed and Dr. Abrahamson agreed that ergodic assumptions in this context may not be fully correct. Time-dependent behavior and uncertainties were also captured in the standard model which is used in seismic hazard analysis which is not dependent upon the time of occurrence of the last earthquake, as earthquake occurrence is random. Dr. Abrahamson observed, however, when data is analyzed most regions violate the principle of randomness and there is a temporal variation in the rate of earthquakes and previously the approach he described has only been used on faults with lots of information such as the San Andreas Fault and that less information means less certainty and relative to the Hosgri Fault, where less information is available, the potential is there at either the higher or lower rate for earthquake occurrence.
Dr. Abrahamson stated virtual faults in the area of DCPP were incorporated in the models to describe earthquakes that could happen in the Irish Hills on faults that were not identified, and these virtual faults were used in seismic source characterization models. He displayed a graphic with a map of those virtual (i.e., assumed) faults with dips ranging from vertical to 45 degrees in both directions with a rate assigned equivalent to approximately 0.2 millimeters per year on any one of the virtual faults.
Dr. Abrahamson reviewed the Hosgri Fault slip rate analysis and observed the area on shore where the Hosgri and San Simeon Faults intersect provides a location where geologists have been able to examine the faults and estimate slip rates. Three additional data points were used in the seismic source characterization model and these were located, running from north to south, at Estero Point, South Estero Bay, and at Point Sal. He remarked paleo stream channels were identified using offshore geophysical data from when the sea level was lower and a Hosgri Fault slip rate was able to be estimated at those three locations. He confirmed Dr. Budnitz’ observation that the largest uncertainty in this effort is age dating but Dr. Abrahamson stated geodetic data was integrated and shows how much horizontal slip can be happening. Dr. Abrahamson stated this new approach used off shore geophysical data integrated with the original on shore estimates and developed a distribution of what the slip rate could be, and these distributions were assigned subjective weight based upon the quality of the data and a composite distribution of their weighted average was made. This resulted in revising previous estimated slip rates for the Hosgri Fault from a broad range of 0.5 to 6.0 millimeters per year to a narrower range of between 0.5to 3.0 millimeters per year in terms of what the slip rate could be and still be consistent with observations, with 1.7 millimeters being the median value of the center of that range. Dr. Abrahamson stated more is now known than before and the 6.0 millimeter per year slip rate has proven not to be a credible model. In response to Dr. Budnitz observation, Dr. Abrahamson stated the fact the slip rate is lower at the southern end of the fault is because as you move south on the Hosgri Fault the slip rate is reduced as it is distributed into different portions of the fault system. For this seismic source characterization work PG&E has used the average slip rate that applies to the 170 kilometer length of the Hosgri and San Simeon Faults together. Dr. Budnitz observed that as DCPP is located approximately in the middle of the 170 kilometer length the slip rate of the Hosgri Fault at the plant site is likely to be in the middle of the range identified by Dr. Abrahamson.
Dr. Abrahamson discussed how the uplift of the Irish Hills is accounted for by discussing three principal thrust fault mechanisms and displayed a diagram of each mechanism describing the compression effects of the Los Osos or San Luis Bay Faults, or both thrust faults working in conjunction on the uplift of the Irish Hills. Dr. Abrahamson stated that it is not possible to tell which of the three mechanisms is primarily responsible for the uplift. He described the Los Osos Fault as the most well-developed of these features with the San Luis Bay Fault as likely being shallow. Dr. Abrahamson confirmed Dr. Budnitz statement if Dr. Abrahamson had 200 years of geodetic data, with the current precision more could be determined as to the mechanism resulting in the uplift in the Irish Hills. Dr. Abrahamson confirmed that one of the models he discussed is similar to that with inferred offshore faults proposed by Dr. Douglas Hamilton but Dr. Abrahamson commented that Dr. Hamilton’s concept would need to be adjusted somewhat to be consistent with the latest data.
Dr. Abrahamson showed a map of the Hosgri Fault and stated it may be rupturing in earthquakes approximately in the 6.5 to 7.5 magnitude but another possibility is that the Hosgri Fault links up to the San Andreas Fault and a rupture could extend all the way to Cape Mendocino which could result in a magnitude 8.5 earthquake and he confirmed Dr. Budnitz statement that the order of magnitude does not make a significant difference because only the local motion matters for ground motion, but he stated that larger magnitudes are created with larger slips and that this affects the long period energy but not the high frequencies to the same degree and it is the high frequencies which are the most important for nuclear structures.
Dr. Abrahamson displayed graphs of the magnitude density functions and commented with this new data there is an exponential tail to higher magnitudes that allows for earthquakes to rupture together and PG&E is using data from site data collection efforts around the world on variability of slip seen along faults to infer what range of magnitude could occur.
Dr. Abrahamson reviewed what he termed a seismic source characterization equivalent, the Poisson process rates and he remarked that the Poisson process is one in which there is no memory in the system and there is a chance of an earthquake happening at any point in time. This is achieved with an exponential distribution of recurrence times and the Poisson process model is contrasted with a method which uses a systematic repeatable or semi periodic behavior of the fault with a wide range. PG&E has assumed an exponential Poisson model for all faults for which it does not have significant information, which translates to more uncertainty and a broad range of how long it might have been since the last earthquake.
Dr. Abrahamson then discussed the ground motion model work done by PG&E. He stated the reference rock ground motion model predicts a median or an average ground motion for a given magnitude and distance away and also predicts the aleatory variability, that is, how much the ground motion can randomly vary from one earthquake to another. Dr. Abrahamson stated wave propagation through the earth’s crust is more complex that just the distance away from the source and site response is much more complex than shear wave velocity. He remarked that because PG&E used a very simple description of the earthquake source and wave propagation process in the median, the penalty is large variability which he described as the aleatory variability term which affects the shape of the hazard curve. He reported site amplification is also controlling as to ground motion and is analyzed by assessing how the ground motion at the defined control point differs from the reference motion model which is built from world-wide data. Dr. Abrahamson remarked that the epistemic uncertainties need to be captured in this effort and to do that, in response to Consultant Linnen’s question on the relationship of the modeling effort and the data, Dr. Abrahamson stated that the model, consistent with the SSHAC procedures, is pushed to the limits of the available data, that is as far as possible, so that the data that is available is not violated. Dr. Budnitz observed that as the data are limited there are numerous models that are consistent with the data.
Dr. Abrahamson reviewed the new ground motion component data, methods and models including that of the Pacific Earthquake Engineering Research Center (PEER) at Berkeley, CA, developed using empirical data sets of ground motion models and what is called the NGA-W2 Ground Motion Data Set consisting of 20,000 records from earthquakes around the world. European data sets were reviewed but Dr. Abrahamson who stated these tend to be of smaller magnitudes. Numerical simulations were also reviewed and used.
Dr. Abrahamson reported on the classes of models available which are used to determine the ground motion prediction equation (GMPE) and remarked they consist of much more than empirical models but have physics built into them to allow them to be pushed to extrapolate the model in any direction. He remarked that finite-fault simulations are an important constraint on the modeling behaviors to get realizations of different earthquakes as opposed to the limited number of earthquakes in the empirical data set. He confirmed Dr. Budnitz’ observation that the reason the GMPEs for DCPP are different is because of the fact there is more usable data available due to more instrumentation having been deployed from the days of the initiation of the Long Term Seismic Program with 300 recordings, to the 1990's with 800 recordings, to the early 2000's with 3,000 records to today’s data with approximately 20,000 records. Dr. Abrahamson stated that the earlier GMPEs also had physical model behaviors imbedded which allowed them to work as well as they have. In response to Dr. Lam’s inquiry, Dr. Abrahamson stated that the first strong motion recordings were made in the 1930's and the recordings that were used for the most recent PG&E analysis continued up to 2012. He reported that there are now 90,000 recordings from subduction earthquakes. Worldwide average models will be in accordance with ergodic assumptions which will result in large uncertainties but they will be credible for use in California. In response to Dr. Budnitz’ inquiry, Dr. Abrahamson stated the best earthquake data in the area of DCPP was recorded during the San Simeon earthquake and this data will be combined with data from around the world to get an average that captures larger standard deviation or larger variables that influence the hazard calculation. In response to Consultant Linnen’s inquiry, Dr. Abrahamson stated the Kobe earthquake in Japan was an earthquake similar to what would have occurred in California had the earthquake taken place there. Other regions such as the eastern portion of the United States are more stable continental regions and there are other areas which are located in subduction regions. As the data sets get larger, differences between regions are seen and behaviors, particularly the manner of attenuation with distance, are being identified. Ground motion modeling is moving toward region-specificity and as more data is accumulated the models will shift for the various regions and the variability within the region will get smaller which will lead to steeper hazard curves. In discussing the aleatory model, Dr. Abrahamson stated the issue of concern is not the average earthquake but the rare earthquake and with the data sets now available analysis can go out to four standard deviations to understand what is happening at the tail of the distribution curve, and what Dr. Abrahamson described as a mixture model is being implemented to analyze the tail of the curve.
Dr. Abrahamson reported that a key feature of the new hazard analysis tools uses what he termed a Sammons Map approach to address the evolution of peer review reports and the resulting increase in uncertainties. He stated the Sammons Map approach requires pushing and broadening the models created to the maximum of their credible range. This results in an additional epistemic uncertainty being added to all the models. The models are then evaluated against empirical data, particularly California data, and against theoretical finite fault simulations developed for particular areas such as the Hosgri Fault and the Central California Coastal Range. What Dr. Abrahamson described as the Single Station Sigma approach is also used which moves the analysis away from lumping all the data from around the world together, as sufficient data exists to estimate how much one station differs from another, with the uncertainty addressed in context of the Single Station Sigma approach by the epistemic uncertainty of the site response.
Dr. Abrahamson displayed and discussed graphics with the mean hazard curves and a Sammons Map calculation and the hazard results and response spectrum for a control point located at an elevation of 85 feet north of the plant. He commented the curves are not flat but have peaks which represent observations at the site which show a site resonance at about 2.5 Hertz (Hz) with more attenuation in the high frequency range. He stated this shows how the analysis is moving to a partially non ergodic model as it is accounting for how DCPP behaves differently than an average site around the world in the same category. He reported the Ground Motion Response Spectrum (GMRS) for Diablo Canyon is very close to 10 -4 uniform hazard spectrum.
Dr. Abrahamson provided data from the Parkfield earthquake and the recordings of that earthquake from Diablo Canyon, which he described as lower than the average of the compared observed data and he stated an important part of the analysis is the use of the other recordings so that the average difference in that earthquake, the average difference in the wave propagation, can be taken out, which leaves the site effects portion of the data. He reported that for DCPP there are two earthquakes for which this data is available, the San Simeon earthquake with eight recordings and the Parkfield earthquake with 16 recordings. This results in a standard error for the San Simeon earthquake being 0.25 and for the Parkfield earthquake 0.14. He showed a graphic with the results of the averages for the San Simeon and Parkfield events and stated the results show the two earthquakes have very similar behaviors relative to site response at DCPP. He reported that for lower frequencies the data becomes less consistent and he confirmed Dr. Peterson’s comment that it appears that the high frequency energy is attenuated more than the ergodic model would suggest and it does not appear to be strongly direction dependent in terms of the two earthquakes and therefore concerns about directionality are not as important for higher frequencies as they would be for lower frequencies. Dr. Abrahamson confirmed Dr. Peterson’s observation that the plant tends to be sensitive at somewhat high frequencies and reported that 3 to 5 Hz is the main frequency ranges for DCPP. Dr. Peterson observed this is the range where there is concern about fragility and it appears that at those frequencies energy does not propagate as much as the ergodic model would indicate. Dr. Abrahamson replied that at 3 Hz the energy does propagate which is the same or somewhat higher than the ergodic model and at 8 Hz it is lower and he remarked it is important to keep in mind there is still uncertainty in how well the average site term is estimated.
Dr. Abrahamson reported the surveys done for geophysical characteristics at DCPP are useful to understand the geometry beneath the plant and represent a unique data set as there is no other location in the world with this kind of information including 3-D velocity models estimated with tomography which provides velocities on about a 20' x 20' square horizontal area and a 5' vertical grid under the plant site. He displayed a 1-D velocity profile which showed the range in the DCPP units, U-1 and U-2, and in the Turbine Building. He commented the differences will be accounted for using the 3-D wave propagation model using the control point north of the plant and translating that laterally to the other structures.
Dr. Lam stated he has a great deal of deference to the complex technical information presented by Dr. Abrahamson as it provides a level of comfort concerning seismic reactor safety but he stated his belief that this science has yet to reach its maturity as it cannot predict when, where, and how big the next earthquake to occur will be. Dr. Abrahamson stated he could not make such a prediction but he could say that those earthquakes which he described in his presentation will happen eventually as the faults involved have to move a certain amount over thousands of years to stay in equilibrium and this can allow models to be built based on the rate of occurrence average. For the size of an earthquake, science uses behaviors observed from earthquakes around the world and that data is used in conjunction with the ground motion model. Dr. Abrahamson, in response to Dr. Lam’s inquiry, stated that he believes that when, where and how big the next earthquake will be is an incorrect inquiry. Dr. Lam observed that in licensing DCPP and other nuclear power plants the NRC assigned a seismic design basis and this indicated to Dr. Lam that someone addressed and answered that inquiry. Dr. Abrahamson stated the seismic design basis was addressed by a different line of inquiry that being a design which will cover the entire range of seismic events and the NRC is addressing the question based upon whether the risk probability for ground shaking from a seismic event is acceptably low. Dr. Abrahamson stated there has never been a concept that a certain magnitude event will occur and that there exists a bounding value which has no chance of being exceeded. The concept has always been if you design for a postulated event it will give an acceptable and adequate level of safety. Dr. Peterson observed this is the same concept used in designing most types of civil infrastructure. In response to Dr. Lam’s inquiry concerning the possibility of a larger event than the design basis, Dr. Abrahamson replied that this is why the probabilistic risk analysis is done. Dr. Peterson remarked that one of the DCISC’s objectives in reviewing the FLEX initiative is to understand what types of structural and equipment failures can happen during earthquakes as even weak earthquakes tend to focus energy in a certain frequency range that may cause damage and there needs to be assurance that the plant has the capability, equipment, personnel, resources and authority to restore basic safety functions.
Dr. Budnitz stated the work described by Dr. Abrahamson is attempting to enable a description of the state of knowledge for seismic events and this includes more than the magnitude of an event but also what frequencies will be produced and for what durations. It is the role of another body to use that information to design a facility for which a third evaluation will determine the risk. Dr. Budnitz commented this process has evolved from the earliest days of the design of nuclear facilities when the standard types of judgments for how structures are designed to resist earthquakes were commonly employed. He stated these judgments are now better understood.
Mr. Nozar Jahangir addressed the DCISC. Mr. Jahangir is a member of the Seismic Engineering group at DCPP and he stated he would discuss the interim evaluation and plans for follow-up action by PG&E. Mr. Jahangir stated that the information provided by Dr. Abrahamson relative to the ground motion at a designated control point north of the plant site is to be used to do the risk evaluation discussed by Dr. Budnitz. He described this as an interim evaluation to show that DCPP is safe. He reviewed the seismic design and licensing basis history for the plant which he stated is well documented and has been studied throughout the last 40 years. After discovery of the Hosgri Fault in the 1970's the plant’s design was reevaluated and retrofitted. In 1984 the NRC included a condition to the plant’s license that requires additional and continuing studies to demonstrate seismic margin, resulting in the Long Term Seismic Program (LTSP) which Mr. Jahangir stated is similar to what was required of all nuclear power plants after the accident at Fukushima.
Mr. Jahangir displayed graphics showing seismic design bases curves for risk evaluation comparisons including the design basis, the double design basis and he stated these were referred to in terms of gravitational acceleration (g) as 0.2 g and 0.4 g peak ground acceleration, together with the Hosgri design basis at 0.75 g and the LTSP seismic margin, equivalent to the new calculation for GMRS, at 0.83 g. In response to Dr. Budnitz’ inquiry, Mr. Jahangir stated that a new plant at the site of DCPP, to meet the NRC’s current requirements, would have to be designed against the GMRS which is a probabilistic evaluation. Mr. Jahangir stated that the lowest margin for DCPP components as evaluated against the LTSP is 35 percent more than the spectral frequency that they were evaluated for, which means that all the components required for safe shut down of the plant have at least that margin of safety with some having higher margins. He confirmed Dr. Budnitz’ observation that this represents the inherent capacity of the system to provide that level of margin over the LTSP. Dr. Budnitz stated he has in the past expressed his belief that there was no component important for safety at DCPP whose seismic capacity, i.e., strength, was not stronger than the LTSP and Mr. Jahangir has quantified that statement by his presentation this evening and Dr. Budnitz stated further that the plant’s components are also thereby shown to be stronger than the GMRS which represents today’s best understanding. Mr. Jahangir stated by doing the interim evaluation PG&E has shown that DCPP has a reasonable assurance of safety while the seismic risk continues to be updated for new hazards.
Mr. Jahangir reported PG&E is proceeding with its Seismic Probabilistic Risk Assessment (SPRA) including updating and building models, updating the soil structure and interactions (SSI) models and developing the foundation input response spectra (FIRS) models. A fragility evaluation will be done as part of the SPRA update. He reported the next actions will include the determination in accordance with the risk evaluation prioritization which the NRC recently provided, placing DCPP in a group one category which requires the evaluation be completed by June 2017. To meet this requirement PG&E will need the NRC’s agreement with the GMRS hazard evaluation before proceeding with SPRA modeling. Dr. Budnitz observed and Mr. Jahangir agreed that the FIRS modeling involves assessing motion at various elevations within the plant to evaluate the impact on and response of particular equipment and this accordingly is conditional on the SSI models. Dr. Budnitz remarked and Mr. Jahangir agreed this is similar to what was done in the LTSP analysis in the 1980's and Mr. Jahangir stated the current effort is upgrading to the new standards for the SPRA using 3-D finite element models and this effort is also being done as part of DCPP’s commitment to the LTSP.
Dr. Abrahamson discussed the efforts and methods used to reduce uncertainties and reviewed a Tornado Diagram comparison of 2011 and 2014 hazard significant parameter uncertainties. He observed the Tornado Diagram summarizes seismic hazard parameters and the impact of a parameter uncertainty on the total hazard uncertainty. Parameters whose uncertainties contribute more to total hazard uncertainty are shown at the top of the diagram. He reported for low probabilities used for nuclear power plants, DCPP at 10 -4 is on the steep portion of the hazard curve he displayed but because the hazard curve is steep the ground motion doesn’t really change that much. He reported the Tornado Diagrams reveal how much the “Y” axis value on the curve changes at a particular number, with essentially the ground motion corresponding to 10 -4 hazard and by changing the ground motion model, the “Y” axis is affected more than by changing the source characterization model. He reviewed and discussed certain of the entries on the Tornado Diagram including the time-dependent model, the models used for the standard deviation including the single sigma model, the site amplification model and the median GMP from the Sammons Map approach. Dr. Abrahamson stated the global models are moving more to region-specific models but mainly at larger distances, and from 50 to 100 to 200 kilometers demonstrate a difference between California and Japan, but in close there is not enough data to distinguish the two models. He stated that data to calibrate the models and more use of 3-D modeling of the crust and propagation of the waves through the 3-D model are needed and that the 3-D model needs to be calibrated against actual data. To constrain the path terms, that is, how waves propagate from the Hosgri Fault to DCPP compared to an average fault five kilometers away, the data will be from mostly small earthquakes but Dr. Abrahamson observed that this data is useful as the crust is primarily linear and the scale can be amplified to assess wave propagation. He stated that in order to improve the analysis, the density of the station coverage by instrumentation, both transitional seismic stations and alternatives for mass deployment, must be increased. Dr. Abrahamson reported this has been done with a 3-D crustal model by the Southern California Earthquake Center in Los Angeles which has built what he described as a huge model of what is occurring in terms of how the ground motion is affected by complex crustal behavior and Dr. Abrahamson stated numerical simulations are the way to get dense coverage and to increase understanding but DCPP needs more data for validation and calibration of the 3-D velocity model currently being built although there is adequate data to commence this effort. He remarked that much of this can be done with micro tremors to obtain data to constrain large scale crustal structures. Dr. Abrahamson stated that as the speed of computer simulations has improved, with approximately one-month run times for this data, science is now ready to move forward with this type of application but enough seismic stations will be required to test and constrain the model and this is an area where advances are being made although it may take up to five years until the results start to be usable and to reach the application stage. Dr. Abrahamson stated that this represents the future of seismic hazard analysis, to account for local features and how ground motion works in a particular area and in response to Dr. Budnitz’ inquiry he stated that the seismic community largely understands the approach he described.
In response to Dr. Lam’s further inquiry on when, where and how big an earthquake may be, Dr. Abrahamson replied that he can determine the probability of a magnitude 7 or larger earthquake happening on the Hosgri Fault in the next ten years and he can provide the range of what that estimate is, but no one can determine when the next earthquake will occur. He stated the task of seismic science in this context is to design not for a particular future earthquake but to design for the ability to withstand a range of possible future earthquakes. He stated that a program able to predict when the next earthquake will happen would be a much more ambitious undertaking.
Dr. Peterson thanked Dr. Abrahamson for his presentation.
Dr. Gene Nelson of the Cuesta College faculty, present in the audience, was recognized. Dr. Nelson stated an important aspect of Dr. Abrahamson’s presentation was the fact that it is not necessary to set off charges of dynamite to obtain seismic information and that valuable information to assess how energy propagates can be obtained from naturally occurring earthquakes.
Ms. Gina Mori, a member of the public, was recognized. Ms. Mori commented that while science cannot predict earthquakes, the aftermath of earthquakes can be predicted such as the Bay Bridge collapse or extensive damage to buildings in Napa and that nature is going to do what it is going to do. She remarked that she was concerned that there was no mention in Dr. Abrahamson’s presentation of the spent fuel pools, dry cask storage, or the recently discovered Shoreline Fault. She stated that as a site in Bodega Bay was rejected because of earthquake faults, she questions whether DCPP should have been built at all, given the information now known about 13 earthquake faults in the area.
Mr. John Geesman on behalf of the A4NR was recognized. Mr. Geesman stated he wanted to endorse Dr. Abrahamson’s remarks about the utility of gathering data from small earthquakes at the site of DCPP. However, he stated that this is also why PG&E’s program at DCPP has been such a disappointment. He reported that the CPUC authorized in 2010 a program to place four seismometers on the ocean bottom which was entirely noncontroversial and if PG&E were appropriately committed to gathering data on small earthquakes near the site of DCPP this would have been done immediately after the CPUC approval was received. However, he stated PG&E waited several years and the instruments which were placed on the ocean bottom are still not working properly. Mr. Geesman remarked that the fact PG&E is using only two earthquakes was criticized by the NRC in 2012 and by the CPUC Independent Peer Review Panel (IPRP) in 2013. He commented the IPRP has been harshly critical of PG&E’s ground motion modeling and the site response characteristic efforts. In response he stated PG&E proceeded to cut-off contact with the IPRP and did not meet with the IPRP for nine or ten months and did not hold a public meeting with the IPRP for fifteen months. He remarked the graphs in the IPRP’s Report No. 9 (included with the public agenda packet) were alarming. Mr. Geesman stated this seismic investigation program is funded by PG&E’s ratepayers and it is the most expensive seismic reevaluation in history, costing $64,250,000 of which PG&E has expended $51,000,000 to date. He stated that the Tornado Diagram displayed by Dr. Abrahamson indicates that in this effort PG&E has not paid attention to the most significant aspects of hazard uncertainty itself and has simply looked in the wrong areas and prioritized its expenditures on the wrong subjects while ignoring the IPRP and being called to account for having done so. Mr. Geesman closed his comments by referring to information his client, the A4NR, received from retired NRC regional administrator Mr. Art Howe describing comments by Mr. Howe’s predecessor, Mr. Elmo Collins, who is now a consultant to PG&E advising PG&E not to pursue a re licensing for DCPP for reasons having to do with seismic issues. Mr. Geesman stated the DCISC has an obligation to use its contacts at the NRC to attempt to determine what Mr. Collins was talking about and the relevance of his comments to the Committee’s evaluation of PG&E’s seismic assessment. Mr. Geesman stated such a review would likely find $64,000,000 misspent and that work had been delayed. He stated he was encouraged by Dr. Abrahamson’s statement that perhaps five years would be required for completion of work as Dr. Abrahamson previously advised the IPRP that ten years would be necessary and Mr. Geesman opined the plant would be closed in ten years. In concluding his remarks Mr. Geesman stated he can understand the motivation to participate in the most advanced science concerning seismic modeling or ground motion modeling but the DCISC’s remit is specific to DCPP and the $64,000,000 in ratepayer funds was not intended to fund a worldwide seismic assessment but to evaluation DCPP.
Mr. David Weisman of the A4NR was recognized. Mr. Weisman stated that in addition to the scientific aspect discussed by Dr. Abrahamson there is a social science component to the peer review process mandated by the SSHAC process which needs to be considered as it is the members of that community who make decisions as to what is included and excluded. Mr. Weisman stated his belief that this process is akin to building on fill and not solid rock. He played a video in which persons participating in a meeting exchange hats in recognition of the various roles they might play in participating in a SSHAC peer review process.
Ms. Rochelle Becker of the A4NR was recognized. Ms. Becker stated her organization was founded in 2005 to discuss reliance on an aging nuclear plant beyond its current license. She stated the A4NR argued for the seismic studies and advocated for funding for them. A4NR representatives have attended all of the IPRP meetings. Ms. Becker stated she is tired of paying for what is being offered and $64,000,000 does not come close to meeting PG&E’s requests but its ratepayers have reached the maximum.
Dr. Gene Nelson was recognized. Dr. Nelson again called the DCISC’s attention to the statement he provided to the NRC which is part of the record. He remarked the statements made and video shown are but a charade as they are not representative of critical thinking or scientific or engineering principles but are instead propaganda.
Ms. Kathy Oliver was recognized and described herself as a San Luis Obispo County PG&E ratepayer. She stated she was appalled to hear that $64,000,000 is to be spent studying what she described as an outdated technology as those funds could have provided solar or some type of renewable energy for the whole county.
Ms. Sherry Lewis of Mothers for Peace was recognized. Ms. Lewis commented on the graph used by Dr. Abrahamson during his presentation to display hazard curves from various seismic events and stated the licensing basis for DCPP requires the design earthquake, which she described as the largest feasible earthquake on a fault at Diablo Canyon, and the double design earthquake which is twice that. She stated the evaluation of the Hosgri Fault did not use the double design category as it should have. She questioned whether the data displayed by Dr. Abrahamson represented the same ground motion variable and she remarked the double design equivalent must be applied to all the known faults and, to date it has not been applied to the Hosgri Fault which is treated as an exception. When the Shoreline Fault was found PG&E wanted to include it under that same exception and this was allowed simply because the Shoreline Fault is considered to be smaller than the Hosgri Fault. She stated, however, that the double design aspect is still part of DCPP’s license and the plant is not within that regulation and should be shut down. She stated that while she found Dr. Abrahamson’s presentation fascinating it was difficult to understand. She closed her remarks by stating she would like to ask Dr. Abrahamson’s opinion of Senator Blakeslee’s report on PG&E’s seismic studies as Senator Blakeslee played an important role in initiating those efforts by his introduction of AB 1632.
XI Adjourn Evening Meeting
Dr. Peterson stated that the comments and questions from the members of the public will be entered into the record of the Committee and the DCISC will be responsive to them. The Chair commented the Committee has scheduled a public tour of DCPP for the following morning and the public meeting of the Committee will reconvene at 12:30 P.M. tomorrow. Dr. Peterson then adjourned the evening meeting of the Committee at 8:50 P.M.
Public Tour of Diablo Canyon Power Plant
The three members of the DCISC accompanied by 25 members of the public, PG&E tour guide Mr. John Lindsey and the Committee’s Consultants and Assistant Legal Counsel, conducted a tour of certain accessible areas of the Diablo Canyon Power Plant (DCPP). The members of the public responded to the DCISC advertisement concerning the public tour placed in a local area newspaper and on the DCISC’s website. The group met at the PG&E Energy Education Center for an introduction to the Committee members and consultants and a short presentation on the background and role of the Committee. Mr. Lindsey provided a brief overview of DCPP including its history, operation, the nuclear fuel cycle, spent fuel storage and plant security. PG&E discussed how the plant’s cooling systems work, with the ocean water two physical barriers away from the reactors. The group was issued visitor badges and then departed for DCPP.
After entering the plant through the Avila gate, the members of the public and visited the Control Room Simulator Facility and viewed the ocean water Intake and Outfall Facilities where DCPP pulls in and expels seawater used for cooling. The bus then drove by the site of the Independent Spent Fuel Storage Installation (ISFSI) for a description of its purpose and features and then stopped at the plant overlook site and the group received a briefing from PG&E representatives on the various external features and buildings. The tour did not enter the controlled areas of the plant.
Questions & Comments From the Public
During the ride back to the Energy Education Center the group received information on radiation protection and members of the public took the opportunity to ask questions of Committee members and consultants.
Conclude Public Tour
XXI Reconvene For Afternoon Meeting
The June 17, 2015, afternoon public meeting of the Diablo Canyon Independent Safety Committee was called to order by its Chair, Dr. Per Peterson, at 12:30 P.M. Dr. Peterson welcomed those present and attending remotely by live streaming video to the meeting. He reported the Committee conducted a tour of the plant during the morning which was well received.
XXII Committee Member Comments
There were no comments by members at this time.
XXIII Public Comments and Communication
The Chair invited any comments from members of the public.
Mr. Sherry Lewis of Mothers for Peace was recognized. Ms. Lewis stated that while she did not understand all of the information presented last evening by Dr. Abrahamson she appreciated and understood the discussion concerning reducing the uncertainty of seismic knowledge concerning DCPP. She observed that Dr. Abrahamson reported that there is simply not enough known about the seismic conditions and that it might take five to ten years to acquire the additional knowledge from micro-seismic activity. She stated her opinion that the nuclear industry and regulators present information to the public in a way that makes it appear they know more than they do and that there is a gap between the science and the nuclear industry and its regulators. She stated the industry is interested in the fact DCPP is already built and is trying to make it as safe as possible but that may not be quite safe enough to those in the local area, in the vicinity of many earthquake faults and she stated her belief that the plant would never have been built had more been known and it should be shut down as it is dangerous and the risks are too great. She likened operating DCPP to traveling on the Titanic in iceberg infested areas.
Ms. Rochelle Becker of A4NR was recognized. Ms. Becker reported on May 27, 2015, the CPUC sent a letter to PG&E identifying 18 specific issues to be addressed before the CPUC would consider providing funding for a license extension for DCPP. She observed these issues include seismic studies, liability insurance, lessons learned from Fukushima and the recommendations of the IPRP. As the DCISC was not copied on the letter Ms. Becker offered to provide a copy to the Committee.
Dr. Peterson remarked he appreciated Ms. Lewis’ comments and stated the Committee will continue to review these issues and he looks forward to receiving the CPUC letter mentioned by Ms. Becker. Dr. Lam stated receiving the letter from Ms. Becker would be helpful and he inquired whether the Committee would otherwise have received a copy. Assistant Legal Counsel Rathie replied that a copy would likely be provided only if there was a service list for the matter which included the Committee or if it was provided by PG&E as part of the monthly document transmittal.
Dr. Peterson asked Dr. Budnitz to make the next presentation.
Informational Presentation By the Committee
Report on Its Activities Related to Understanding the Seismic Hazard and Tsunami Risk at the Plant Site and Environs.
Concerning the DCISC investigation of the tsunami risk to DCPP, Dr. Budnitz remarked that understanding the hazard was only part of understanding the risk. He reported PG&E submitted its tsunami analysis to the NRC on March 12, 2015. Dr. Budnitz stated this analysis represents a summary of an extensive body of work. On March 30, 2015, Dr. Budnitz and Consultant Linnen met with PG&E in San Francisco and received an extensive briefing on the tsunami hazard work. The DCISC had the benefit of participation by Dr. Robert T. Sewell, a recognized expert in the area of tsunami analysis, who has been engaged as a consultant to the DCISC to perform an independent analysis of PG&E’s analysis. Dr. Budnitz remarked a great deal of technical information has been assembled by PG&E to support its tsunami analysis and the DCISC with Dr. Sewell will study and review this information and the Committee hopes to be in a position to provide a report by Dr. Sewell at its October 2015 public meeting. Dr. Budnitz stated that the NRC will conduct a separate review and while he serves as a consultant to the NRC staff on the external flooding submittals from other nuclear power plants he has recused himself in that role from any review of the PG&E submission for DCPP. Dr. Budnitz stated that the results of the NRC review are not expected to be available for approximately one year, as there are many nuclear power plants located in the east and in the mid-west where external flooding is more of a threat than at DCPP. The PG&E tsunami analysis will also be reviewed by the community of experts who do this work and the DCISC, PG&E and the NRC will have the benefit of this review. Dr. Budnitz stated that the principal consultant used by PG&E for the tsunami analysis, Dr. Stephen Grilli of the University of Rhode Island, is an acknowledged expert and the work done for PG&E is excellent. The DCISC will closely monitor this review process to understand what is learned.
Dr. Budnitz commented that the DCISC review will include assessing whether flooding might affect plant safety by its impact on any plant equipment or interaction with plant systems. He reported there is a standard established by the American Society of Mechanical Engineers (ASME) and the American Nuclear Society (ANS) which governs how to do external flooding analysis. Dr. Budnitz reported this standard is now under revision by a committee he chairs and a working group of that committee is chaired by Dr. Sewell.
Dr. Lam stated he is appreciative of Dr. Budnitz taking a leading role for the Committee in the tsunami and seismic risk study. He stated he is hopeful these efforts will shed light on reconciling the differences in the magnitude of certain parameters used in the 2003 study by Dr. Sewell and those used in PG&E’s analysis. Dr. Lam also reported for the record that Dr. Sewell is serving in a consultant capacity on an unrelated project contracted for by PG&E. Dr. Lam also stated he hoped Dr. Budnitz’ efforts might shed some light on certain controversial material provided to the Committee by Mr. Weisman about CPUC current legal proceedings regarding electronic communication between PG&E as the DCPP licensee and other technical personnel.
Dr. Peterson remarked that the DCISC’s particular effort will be focused on tsunami data which indicate a tsunami run-up could exceed 85 feet and to understand the nature of that risk and what the impact on the plant from such an event might be. Integral to this investigation would be review of paleo geologic data for tsunamis that have occurred in the past with a return frequency sufficiently high to be of concern relative to the plant’s design basis.
Dr. Gene Nelson, on the physical science faculty at Cuesta College and government liaison for Californians for Green Nuclear Power was recognized. Dr. Nelson stated he submitted voluminous information of scientific and engineering studies regarding DCPP to the DCISC. He remarked that opponents of DCPP continue to exaggerate the tsunami risk as earthquakes in the region are produced by strike slip faulting which does not tend to generate large tsunamis. Critical plant safety systems are located 85 feet or more above sea level. He reviewed the effects of two large earthquakes which took place in the recent past in Japan and Chile. He stated he was grateful the DCISC is composed of experienced and knowledgeable scientists and engineers who practice critical thinking when evaluating evidence presented by experts and the public.
Ms. Sherry Lewis of Mothers for Peace was recognized. In response to her inquiry concerning the nature of the work which Dr. Sewell is performing for PG&E Dr. Peterson replied the work is being done under a contract with a consulting company with which Dr. Sewell is associated and, while this engagement is believed to be related in some way to DCPP, it is not related in any way to the study of tsunamis.
Mr. David Weisman of the A4NR was recognized. Mr. Weisman remarked that once again social science is at work on the issue of the tsunami analysis for DCPP and he stated his interest may not lie with the specific details of the results but rather with a federal agency suppressing information. He stated that the NRC did not subject the 2003 Sewell tsunami study to an external peer review process but instead put the study in a drawer without any objective reason to decide it wasn’t needed or didn’t meet the merits of scientific criteria. Mr. Weisman noted that an 85 foot wave would submerge Avila Beach and the NRC sat on information that such an event might be possible and did not choose to share that information with the California Coastal Commission which has responsibility for producing wave run-up maps. Mr. Weisman stated this serves from a process point of view as a cautionary tale of a lack of transparency and it is the public and the state who are being ill served. Mr. Weisman displayed an exhibit created for an art show tracing public statements, internal emails obtained by FOIA requests, and the information that was previously redacted. He stated this represents an exercise not in science but in democracy and that it is important to realize that science meets public policy at some point and public policy needs to remain open and transparent.
Dr. Budnitz reviewed the PG&E submission of its seismic study for DCPP to the NRC on March 12, 2015, and he stated the NRC staff is now engaged in reviewing PG&E’s submittal on a high priority basis as DCPP is the highest priority plant in the country for the NRC relative to seismic safety. Dr. Budnitz, in his role as a consultant to the NRC staff, has, as he has done with the external flooding analysis, recused himself from any involvement in the NRC’s review of seismic information submitted with PG&E’s March 12, 2015, submission. Dr. Budnitz reported that Dr. Abrahamson has recently participated in seeking to have the methodology used for the PG&E seismic studies critically reviewed by outside experts and there is great interest in the seismic community as the work described earlier by Dr. Abrahamson is far advanced and the controversy over the seismic hazard at the plant has been ongoing for more than 30 years. The DCISC will continue to follow this process. Dr. Budnitz stated he estimates that the NRC review may be complete and available for review by the DCISC and others within six months, that is, by the end of 2015. The DCISC will also follow critiques of the methodology from other seismic experts and by the IPRP.
Dr. Budnitz stated the NRC developed a standardized methodology, known as Appendix A Part 100, which was adopted after DCPP’s first seismic licensing work and which established the design earthquake (DE), which he described as a function of frequency. Some plant components being sensitive at frequencies of 3 Hz some at 12 Hz, with structures tending to be sensitive at 1-2 Hz and equipment tending to be sensitive between 3-10 Hz or between 15-30 Hz. Upon discovery of the Hosgri Fault the plant was required to design to and use the double design earthquake (DDE) until a more thorough investigation of the Hosgri Fault was completed. Subsequently it was determined that the Hosgri Fault earthquake should control the plant design (HE). Dr. Budnitz observed that some concrete had already been poured and equipment designed prior to the establishment of the HE as controlling the design and these components while not designed to the HE standards were evaluated against them. When evaluated against the HE, which would have been the design of everything had it been known at the start of construction, most components were found to have sufficient margin but some required replacement or were upgraded.
Dr. Budnitz reported that subsequently the NRC required PG&E to undertake the Long Term Seismic Program which produced a spectrum (LTS) against which the plant was reanalyzed and redesigned in the 1988-1989 period. This was followed by PG&E’s most recent efforts which produced a spectrum, known as the ground motion response spectrum (GMRS) that if the plant were to be designed today would be controlling per Appendix A Part 100. Dr. Budnitz observed that GMRS is the new reference for what the NRC previously referred to as the safe shut down earthquake. If data produced to date by PG&E shows that the GMRS is accurate then it should not be necessary to redesign anything as the plant actually has more margin, as everything was previously qualified to the HE curve. Dr. Budnitz confirmed that the DCISC will review the continuing analysis of PG&E’s work and will follow the review and possible endorsement or lack thereof by the seismic community including as data is compiled over the next five to ten years.
Dr. Budnitz displayed a graphic used by Dr. Abrahamson of the various hazard curves and reported that the other element of the DCISC’s review will include reviewing the seismic input from earthquakes in terms of the design of equipment which needs to be designed to the whole spectrum. He reported when equipment was evaluated in 1988-1989, the weakest components were determined to have sufficient margin to exceed that required by the LTS hazard curve which has provided the basis for Dr. Budnitz’ opinion to date on the seismic strength of DCPP. The DCISC will continue to follow whether the most recent reanalysis by PG&E will be confirmed, but so far Dr. Budnitz reported that PG&E has found no components to be weaker than previously believed but this work is continuing and will be peer reviewed within the seismic community, reviewed by the NRC and by the DCISC before an opinion can be formed about the current safety of the plant. Dr. Budnitz reported that there have been changes in load bearing to the Turbine Deck which will result in different impacts from those analyzed during 1988-1989, and motion must be understood at various levels of that building with reference to the seismic capability of each installed component. Dr. Budnitz stated that this work is expected to take at least one year and he commented that any discovery or finding that a component is weaker than previously determined must be reported immediately to the NRC or DCPP would risks receiving a violation under 10 CFR Part 21. In response to Consultant Linnen’s question Dr. Budnitz stated equipment can be evaluated for its seismic capacity through the use of shaker tables, by use of scale models, and by industry experience documented at other facilities during earthquakes. In response to Consultant Linnen’s question Dr. Budnitz stated the LTSP, the state of knowledge after the development of the HE, represented an understanding of the seismic motion.
Mr. John Geesman of the A4NR was recognized. Mr. Geesman observed that the LTSP review and redesign came at a cost of $4.2 billion and he remarked the DCISC’s concerns are narrower due to its remit from the CPUC than those of the A4NR. Dr. Budnitz responded to confirm that PG&E’s current reanalysis includes NRC safety-classified as well as other components as such components may play important roles following an earthquake. Mr. Geesman noted that the DCISC is a state-appointed panel and the State of California has concerns broader than those of the DCISC relative to plant safety including the potential cost of retrofit. Mr. Geesman observed from Dr. Budnitz’ presentation it appears that the DCISC’s analysis will for the most part be reactive to what others discover about PG&E’s seismic assessment and he suggested that the DCISC pay careful attention and consider of serious consequence the work done by the IPRP, which includes representatives from the CPUC and the California Coastal Commission. Mr. Geesman observed the graphics produced by the IPRP in its report arrive at starkly different conclusions than those in PG&E’s presentation and as used by Dr. Budnitz in making his comments and the IPRP will have a significant say in any decision to re license DCPP. Mr. Geesman remarked that the hazard model and the site response model discussed by Dr. Budnitz were not subjected to the same review using the SSHAC process as were the seismic source characteristic or the ground motion characteristic models and he questioned how a level of comfort can be derived that the site response and hazard impact, two critical inputs, are going to get the adequate level of scrutiny which the NUREG documents require for the seismic source characteristic and ground motion models. In closing his comments Mr. Geesman suggested that in its review the DCISC be concerned with and look particularly at the 3-D tomographic models used to characterize the soil conditions under the plant. He remarked that the presentation made to the IPRP, and references in the CCCSIP, indicate that the model at least recently had extraordinary difficulty in imaging the subsurface in the first 30-40 meters beneath the plant.
Dr. Gene Nelson, a member of the Cuesta College physical sciences faculty and government liaison for Californians for Green Nuclear Power was recognized. Dr. Nelson stated the opponents of DCPP exaggerate the earthquake risk and the key point is that each earthquake safety analysis shows a substantial seismic margin for the plant for any credible earthquake in the area and the plant’s construction is very robust. He stated that an excellent paleo geologic record of lateral stream displacement from strike slip earthquakes is located on the Carrizo Plain in San Luis Obispo County where the San Andreas Fault crosses Wallace Creek.
Ms. Sherry Lewis of Mothers for Peace was recognized. Ms. Lewis commented that Dr. Budnitz reported that components are sensitive at differing frequencies. She understood that when the Hosgri Fault was discovered the double design earthquake (DDE) was developed to provide extra margin until the Hosgri Fault was fully evaluated. Dr. Budnitz confirmed in response to Ms. Lewis comments that not all the Hosgri evaluation (HE) fits under the DDE and Ms. Lewis stated this was an important point and no one could afford to retrofit for a double design basis based upon the Hosgri Fault. Dr. Budnitz commented there was insufficient time to fully explore the historical development of the seismic bases established for DCPP over the years of its construction and operation and his presentation was necessarily focused upon the DCISC’s activities in the future. In response to Ms. Lewis observation Dr. Budnitz replied that it did not matter to him that it appears that the DDE concept is being dropped as the DCISC is not dealing with licensing issues, NRC regulations, or what criteria a particular component was designed to meet but rather his concerns are focused upon the strength and capacity of plant components and what are the inputs used to develop and calculate their strengths and capacities. Dr. Lam stated that Dr. Budnitz’ comments represented Dr. Budnitz’ personal views and Dr. Lam stated that he was concerned that the plant meet NRC regulations and Dr. Budnitz expressed his concurrence with Dr. Lam’s statement regarding NRC regulations.
Ms. Jane Swanson of Mothers for Peace was recognized. Ms. Swanson was granted leave by the Chair at this time to pose questions to the Committee on an item not on the agenda for the public meeting. Ms. Swanson inquired relative to issues of DCPP’s noncompliance with NRC technical specification requirements in loading dry storage casks for an explanation of the function of the control rods that may be inside the casks, who designed the technical specifications directing the loading of the casks, who made the decision or judgment, the Holtec firm or PG&E, to use a different loading method than required by the technical specifications, and finally when did the noncompliant loading method begin and how long has it been going on. Dr. Peterson responded that it is likely control rods were placed within the storage canisters and that the principal reason for doing so is likely that it provides a method for their disposition. He stated that the DCISC, having recently learned of the loading issue with dry storage casks will need to conduct future fact-finding related to the issue of the loading of the dry storage casks and the questions posed by Ms. Swanson will be answered during the fact-finding and reported to the public in due course during a public meeting of the DCISC.
Dr. Budnitz, in response to Mr. Geesman’s earlier observation concerning the lack of a SSHAC process for the hazard and site response models, stated that the reason the SSHAC process was developed was that there were multiple models consistent with the data for seismic source characterization and ground motion modeling and there was a need to assimilate a common understanding with a full range of uncertainty. Dr. Budnitz stated that was not the case for the hazard and site response models where there are only one or two models which are almost equivalent and are widely accepted and understood by the seismic community and accordingly there is very little controversy on how to do a hazard or site response analysis and there is no need for a SSHAC process in that context.
Ms. Elizabeth Brousse of Mothers for Peace was recognized. Ms. Brousse referred to an article in the San Luis Obispo Tribune appearing in October 2013 which reported on the numbers of low level and high level violations by nuclear power plants. She observed DCPP was found to have a large number of low level violations but no high level violations. She inquired whether the loading of the dry storage casks in violation of technical specifications would constitute a high or a low level violation? Dr. Peterson stated that issue was yet to be determined and as the DCISC recently learned of this issue he could not comment further.
XXIV Information Items Before the Committee (Cont’d.)
Dr. Peterson requested Mr. Cary Harbor, Director of Compliance, Alliance and Risk at DCPP to continue with the information presentations. Mr. Harbor introduced Mr. Matthew Shepherd, an engineer in the DCPP Probabilistic Risk Assessment (PRA) group to make the next presentation and reported Mr. Shepherd has a Master’s Degree in Physics and eight years of experience in the nuclear industry.
Presentation on PG&E’s Assessment of DCPP Internal Flooding Probabilistic Risk Assessment.
Mr. Shepherd stated he resides with his family in Paso Robles, CA and in his position at DCPP he acts as a subject matter expert in the area of external flooding PRA modeling.
Mr. Shepherd stated the internal flooding PRA model represents a strong commitment to public safety at DCPP. He remarked risk insights are important and the PRA model is a living model which requires that designs and procedure information be updated. The PRA model looks at the impact of tank or fluid rupture on shut down or on safety-related or mitigating equipment. The internal flooding model does not address tsunamis or seismically-induced pipe ruptures. Mr. Shepherd reported the PRA model demonstrates that the frequency and impact of the ruptures which are analyzed by the internal flooding PRA model contribute approximately 7 percent to the risk profile for DCPP. The internal flooding PRA model is probabilistic in that it looks at a range of breaks, rather than deterministic which would be limited to assessing the impact of a single break or failure. The goal of the internal flooding PRA model is to provide a detailed and realistic analysis and the model examines events and goes beyond the plant’s design basis probabilities. Mr. Shepherd stated that all design and licensing requirements are already met for internal flooding.
Mr. Shepherd reported the DCPP internal flooding PRA model was originally developed in response to NRC Generic Letter 88-20. In recent years, the requirements for a technically acceptable internal flooding PRA have been provided in Regulatory Guide (RG) 1.200, Revision 2 and in the American Society of Mechanical Engineers (ASME)/ American Nuclear Society (ANS) standard for PRA for nuclear power plant applications. In 2012 the internal flooding PRA model was updated to RG 1.200, Revision 2 and the corresponding ASME/ANS Standard.
Mr. Shepherd reported that in December 2012 an independent peer review was performed with respect to RG 1.200, Revision 2. The peer review team was comprised of experienced industry members and expert consultants in internal flooding PRA. The team’s findings and observations were documented by the peer review team. This internal flooding PRA model has been incorporated in the Diablo Canyon PRA model of record.
Mr. Shepherd reviewed two hypothetical internal flooding scenarios and confirmed Dr. Budnitz’ observation that they are hypothetical in that they have never been experienced at DCPP. These scenarios include flooding in the Auxiliary Feedwater (AFW) pump rooms and in the Turbine Building. Regarding the internal flooding scenario for the AFW pump rooms Mr. Shepherd stated the AFW System provides secondary cooling after a plant trip. There are two AFW pump rooms and a fire water piping rupture could affect both as they are connected by a fire damper. He reported that backup systems to the AFW pumps are available and maintenance risks for internal flooding are low but risk management actions are taken when performing maintenance. Concerning internal flooding scenarios in the Turbine Building Mr. Shepherd reported the identified sources for internal flooding result from flows from the Circulating Water System or as a result of a fire water piping rupture. Flooding in the Turbine Building could affect off site power as there is a potential to affect the emergency diesel generators (EDGs). He reviewed the actions and systems available to mitigate these scenarios including the presence of auto-trip sensors or operator action to trip the circulating water pumps and the ability to manually isolate the fire water system. Mr. Shepherd concurred with Dr. Peterson’s observation that internal flooding of the Turbine Building does not assume full flow, as the circulating water pumps can be stopped to limit the flow and Mr. Shepherd reported that the flood rate is broken down to intervals to account for this.
In concluding his presentation, Mr. Shepherd observed that the risk from hypothetical internal flooding is a small portion of the overall risk. DCPP’s design, conformance with standards, procedures and practices provide assurance that these hypothetical flooding scenarios are very unlikely to occur and robust backup safety systems are in place to mitigate such events. Risk insights form the internal flooding PRA model will be used to further enhance safety at DCPP.
In response to Dr. Budnitz’ question, Mr. Shepherd confirmed the internal flooding PRA model meets ASME standards and relies on internal event modeling. In response to Dr. Budnitz inquiry about other sources with the potential to create internal flooding Mr. Shepherd stated that there are other sources which contribute less than the AFW and Turbine Building internal flooding scenarios and those lesser sources are not screened out by the PRA. In response to Dr. Budnitz question Mr. Shepherd stated operator actions are an important contributor to flooding from the raw water reservoirs. Mr. Shepherd confirmed Dr. Budnitz comment that in accordance with standard practice, some plant-specific data were incorporated for the AFW and Turbine Building flooding scenarios which was obtained through review of entries in the Corrective Action Program for pipe leaks and spraying events but this plant-specific data did not contribute appreciably to the results. In response to Dr. Lam’s inquiry, Mr. Shepherd replied that the PRA model incorporates some, but does not take full credit for, operator actions and that approximately 60 total scenarios were used in developing the internal flooding PRA model. In response to Dr. Peterson’s inquiry about the percentage assigned by the model for flooding of the EDGs Mr. Shepherd replied that the frequency of such flooding was very low as a number of failures would be required to have occurred to flood the Turbine Building. In response to Dr. Budnitz’ question as to whether there were any recommended changes identified as a result of the PRA, Mr. Shepherd noted that the fire water piping was already being replaced to address corrosion issues and he stated the principal benefit from the internal flooding PRA model is to online risk management and there were no insights identified for shut down planning. Dr. Peterson observed that the AFW and the Turbine Building were the major contributors to the 7 percent risk percentage and Mr. Shepherd confirmed there were different levels of contribution for these scenarios between U-1 and U-2. He confirmed Dr. Peterson’s comment that plant risk in this context means core damage frequency.
Dr. Peterson remarked that the DCISC during its review of the proposal to replace closed loop cooling with cooling towers received a good deal of negative feedback regarding the Committee’s concern that doing so could increase the risk or require additional mitigation measures.
Dr. Gene Nelson of Californians for Green Nuclear Power was recognized. Dr. Nelson stated he submitted comments regarding his concern that to substitute salt water cooling towers for the present once-through plant cooling system would result in 18,000,000 gallons of conductive seawater becoming located at the 110' level. He stated his opinion that this would result in a very substantial increase in the safety risk and could cause a man-made Fukushima without the need for an earthquake. Dr. Peterson remarked that redundancy and diversity would allow the plant to cope with a loss of electricity, as would employment of the strategies developed as part of the FLEX initiative to pump water to remove heat.
Dr. Budnitz observed that all nuclear power plants conducted a similar review in 1988 and a sizeable number of plants identified and addressed internal flooding issues at that time. He observed that in this new effort there had not been very many additional issues identified and the reason and value for conducting the additional review is to receive reassurance that this is not an area of great concern.
Dr. Peterson remarked that due to the high elevation of cooling towers, a closed cooling system would substantially increase the pressure in the Circulating Water System and result in water being located above the Turbine Building. Dr. Peterson observed that proper engineering could likely manage the change but EDGs are located within the perimeter of the Turbine Building. He reported that the comment of the Friends of the Earth to the DCISC’s concern regarding these issues was that the DCISC was being frivolous. In response to Dr. Peterson’s question Mr. Shepherd confirmed that the PRA model for the internal flooding hazard would change if cooling towers were used to supply plant cooling. Dr. Peterson stated that he believed that the safety impacts of flooding in the Turbine Building should be manageable even with a closed cooling system.
Mr. Harbor introduced DCPP Station Director Jan Nimick and stated Mr. Nimick has more than 20 years’ experience in the nuclear industry including leadership roles in Operations and Maintenance organizations, holds a Senior Reactor Operator License and a Bachelor of Arts Degree in Mechanical Engineering. Mr. Harbor reported Mr. Nimick was promoted to Station Director on January 1, 2015. Dr. Lam congratulated Mr. Nimick on that promotion.
Presentation on the State of the Plant Including Key Events, Highlights and Station Activities.
Mr. Nimick stated his presentation would include an update on the station’s status and upcoming key station activities. He reported the plant is currently operating both U-1 and U-2 in Mode 1 at 100 percent power with Probabilistic Risk Assessments (PRAs) of Green. All NRC Performance Indicators (PI’s) are Green. He reviewed the 2015 Generation Capacity Factor (year to date):
- U-1 = 99.1%
- U- 2 = 101.44%
- Total Plant = 100.27%
Mr. Nimick reported that since 2012 there have been four flashover events brought about by drought conditions causing salt and dirt buildup on insulators which when exposed to wet conditions causes salt to dissolve and creates a conductive path. In March 2015, PG&E’s Transmission organization, as part of an integrated off site power program with DCPP, used a helicopter to hot wash line insulators on the 500 kV towers from Units 1 and 2 to the 500 kV substations. Hot wash of the 500 kV Turbine Building insulators is scheduled for August 2015. Mr. Nimick reported the 500 kV Turbine Building insulators will be replaced during refueling outages 1R19 and 2R19 with the new insulators having 72% more creepage distance and capable of a five-year wash cycle although he commented DCPP plans to wash these insulators during each subsequent refueling outage. The current wash cycle for the insulators requires they be washed approximately every six weeks.
Mr. Nimick stated that the same insulators as DCPP will be installing during 1R19 and 2R19 are currently being tested and used at the Koeberg Nuclear Power Plant located on the coast of South Africa. He remarked the Koeberg plant has environmental conditions similar to DCPP in that it is in a hot, dry, coastal environment. In response to Dr. Budnitz’ question Mr. Nimick replied that good vendor support is being provided and in response to Consultant Linnen’s inquiry he confirmed that the Koeberg plant experienced similar operating experience issue with its insulators as has DCPP.
Mr. Nimick displayed a map showing the locations of the 230 kV Mesa and Morro Bay Substations and the 500 kV Gates and Midway Substations located near Fresno and Bakersfield in California’s Central Valley. He reported that the resistive glaze 165 insulators that affect off site power to DCPP are in the process of being replaced for the 230 kV System. To date 154 of 649 of these insulators have been replaced including all of the insulators at DCPP. Mr. Nimick reviewed the offsite power system available to each DCPP vital bus which provides power available from not only the turbine generators but also from the 230 kV Switchyard, the 500 kV Switchyard and from the emergency diesel generators as backup power sources.
Mr. Nimick reported DCPP is not connected to any regional water system and PG&E has always produced all the water necessary for Diablo Canyon for the last 30 years through the use of a desalination plant located on site. Currently that system has excess production capacity of over an acre foot per day, approximately sixty percent of the system’s capacity. In response to the current drought conditions PG&E and San Luis Obispo County entered into contract for emergency water to be used for fire-fighting purposes. Over the next 120 days a countywide drought task force and PG&E will be studying interconnection feasibility for water use for municipal purposes, with the County reviewing the permitting process and PG&E reviewing the technical and operational issues. In response to Dr. Budnitz’ inquiry Mr. Nimick stated PG&E’s current cost for the water it produces is approximately $3.45 per 1,000 gallons. The desalination system filters seawater and uses ultraviolet light and then pumps the water through reverse osmosis membranes to remove the salt. The water is then pumped to the reservoirs and treated again before being used in the plant. The brine produced by this process is discharged to the ocean.
Mr. Nimick reviewed recent and upcoming station activities including:
- PG&E Hiring Fair held on June 12 to introduce opportunities for full and part time work. Mr. Nimick stated he first worked at DCPP in 1996, while studying at Cal Poly, as a temporary outage worker in the Radiation Protection organization. During refueling outages the plant hires approximately 1,000 individuals as temporary outage workers. In response to Dr. Lam’s inquiry he reported PG&E is looking for entry level employees in the DCPP Operations and Maintenance organizations and has been hiring 20-30 persons each year in recent years and Mr. Nimick observed hiring may accelerate given changing demographics. The hiring fairs also serve the purpose of providing information on how to be a better candidate.
- NRC Public Meeting June 24. Dr. Budnitz remarked he discussed with the NRC Senior Resident Inspector for DCPP the possibility of the NRC scheduling one of its public meetings at the same time as a scheduled public meeting of the DCISC.
- NRC Biennial Emergency Planning Program & Performance—summer
- 1R19 Outage—fall 2015
This concluded the informational presentations requested by the Committee from PG&E for this public meeting.
Following Mr. Nimick’s presentation, Dr. Gene Nelson, a member of the Cuesta College physical sciences faculty and government liaison for Californians for Green Nuclear Power was recognized. Dr. Nelson stated he wished to call attention to his comments of February 4, 2015, wherein he expressed concern about saltwater supplies which might be located above the plant and with calculated salt drift, even with the use of low drift cooling towers which he stated are estimated to produce approximately 1.7 million pounds of salt each year which would be deposited on high voltage insulators and pose an additional safety risk to the plant.
Ms. Sherry Lewis of Mothers for Peace was recognized. Ms. Lewis inquired and Dr. Budnitz confirmed that a desalination plant could be run by use of solar power. Dr. Budnitz responded all that was required was electricity to operate a desalination plant.
XXIV Concluding Remarks & Discussion by Committee Members Of Future DCISC Activities
Dr. Peterson again expressed the thanks of the Committee to PG&E and particular to Mr. Harbor and Ms. Zawalick for their assistance with the informational presentations for this public meeting and to the technicians of AGP Video who recorded and live-streamed the meeting to the internet. Dr. Peterson also expressed the thanks of the Committee to the members of the public who attended and provided their comments to the members. Dr. Peterson observed that approximately one-third to one-half of the items the Committee has identified for fact-finding were identified from comments made by the public.
XXV Adjournment Of Eighty-First Public Meeting
There being no further business, the eighty-first public meeting of the Diablo Canyon Independent Safety Committee was adjourned by its Chair, Dr. Per Peterson, at 2:40 P.M.