Public Meeting

February 21 - 22, 2024

Notice of Remote Participation - Dr. Robert J. Budnitz (PDF)
COVID-19 Non-Emergency Notification (PDF)

Archived Stream Agenda Packet November 14-15 & 30 2023 Fact Finding Report December 12-13 2023 Fact Finding Report January 24-25 2024 Fact Finding Report Informational Presentations

Notice of Public Meeting

The Diablo Canyon Independent Safety Committee Notice of Public Meeting

THE DIABLO CANYON INDEPENDENT SAFETY COMMITTEE
(https://www.dcisc.org)
NOTICE OF PUBLIC MEETING

NOTICE IS HEREBY GIVEN that on February 21-22, 2024, at the Avila Lighthouse Suites Point San Luis Conference Facility located at First & San Francisco Streets, Avila Beach, California, a public meeting will be held by the Diablo Canyon Independent Safety Committee (DCISC) in five separate sessions, at the times indicated, to consider the following matters. You may also participate in the DCISC's public meeting in real-time by accessing the Zoom webinar meeting via the weblink or meeting ID given below or by using any of the phone numbers provided. Webinar attendees can make oral comments or ask questions of the Committee Members during the webinar meeting by using the "Raise Your Hand" feature or by pressing *9 on your telephone keypad if joining by telephone only. If you are unable to attend or participate in real-time, you may email to dcsafety@dcisc.org with the subject line "Public Comment Agenda Item#___" (insert the item number relevant to your comment) or "Public Comment - Non Agenda Item." Comments will be reviewed and distributed before the meeting if received by 5:00 p.m. on Tuesday, February 20, 2024. Comments received after that will be addressed during the item or at the end of the meeting.

Zoom Webinar Meeting ID: 826 3733 9740
https://us02web.zoom.us/j/82637339740
Zoom Webinar Meeting Telephone Only Participation: One tap mobile: +16699006833,,82637339740# US (San Jose); +14086380968,,82637339740# US (San Jose);Or Telephone: Dial(for higher quality, dial a number based on your current location):+1 669 900 6833 US (San Jose);+1 408 638 0968 US (San Jose); +1 669 444 9171 US;+1 253 205 0468 US;+1 253 215 8782 US (Tacoma); +1 346 248 7799 US (Houston);+1 719 359 4580 US;+1 305 224 1968 US; +1 309 205 3325 US;+1 312 626 6799 US (Chicago);+1 360 209 5623 US;+1 386 347 5053 US;+1 507 473 4847 US;+1 564 217 2000 US;+1 646 876 9923 US (New York);+1 646 931 3860 US;+1 689 278 1000 US;+1 301 715 8592 US (Washington DC); International numbers available: https://us02web.zoom.us/u/kqmmD5ip.

1. Morning Session - (02/21/2024) – 9:00 A.M. Opening comments and remarks; receive public comments and communications to the Committee on matters not on the agenda; business session including receipt of PG&E's response to the Committee's 33rd Annual Report on the Safety of Diablo Canyon Nuclear Power Plant (DCPP) Operations - July 1, 2022 - June 30, 2023, acceptance of the Minutes of the September 13-14, 2023, public meeting, review of the Open Items List, reports by Committee Members on activities and scheduling of future public meetings and fact-findings, and a report by a DCISC Technical Consultant on the November 14-15, 2023, fact finding visit.

2. Afternoon Session - (02/21/2024) - 1:15 P.M. Committee member comments; receive public comments and communications to the Committee on matters not on the agenda; reports by DCISC Technical Consultants on the December 12-13, 2023, and January 24-25, 2024, fact finding visits, Committee discussion on the status of governmental agency interactions, DCISC response to SB846 directives, administrative, contractual and financial matters, and regarding new DCISC initiatives related to extended operations under SB846, license renewal, and changes of emphasis for upcoming fact-finding meetings.

3. Evening Session - (02/21/2024) - 5:15 P.M. Committee member comments; receive an informational briefing related to plant safety and operations requested by the Committee from PG&E on Section 4.2 of the new License Renewal Application (Reactor Vessel Neutron Embrittlement Analysis) including a briefing on recent attempt to retrieve Capsule B on Unit1; and a presentation by Committee Consultant Dr. Mark T. Kirk on the results of studies evaluating Unit 1 Reactor Pressure Vessel Integrity and addressing public concerns; public comments on the presentations by PG&E and Dr. Kirk; and receive public comments and communications on matters not on the agenda.

4. Morning Session - (2/22/2024) - 9:00 A.M. Comments by Committee members; receive public comments and communications to the Committee on matters not on the agenda; receive further informational presentations requested by the Committee from PG&E relating to plant safety and operations, including on the "State of the Plant" regarding key events, maintenance outage 1X25 and other station activities since September 2023, a presentation on refueling outage 1R24 results including initial license renewal inspection activities and preparation for refueling outage 2R24, an update on the status of NRC Performance Indicators, Licensee Event Reports, NRC Inspection Reports, NRC current issues and current and future License Amendment Requests, and an update on the proposed new staff retention incentive program in support of continued operation and the results of the 2023 Operating Plan and key elements of the 2024 Operating Plan.

5. Afternoon Session - (02/22/2024) - 1:15 P.M. Comments by Committee members; receive public comments and communications to the Committee on matters not on the agenda; consider informational presentations from PG&E on topics relating to plant safety and operations, including an overview of the new License Renewal Application organization, information contained and highlights of sections of the Application with significant new information, update on the status of the PG&E-sponsored study required under SB846 for conducting an updated seismic assessment, and results of a study required under SB846 by independent consultants to catalog and evaluate any deferred maintenance; and wrap-up discussion by Committee members and confirmation of future site visits, study sessions and public meetings.

The meeting will be webcast in real time at: http://www.slo-span.org/ and through https://www.dcisc.org.
The specific meeting agenda will be available at least 72-hours before the meeting and the agenda together with the staff reports and materials regarding the above meeting agenda items will be available for public review commencing Monday, February 19, 2024, at the Special Collections and Archives Department of the Cal Poly Library in San Luis Obispo and online at at www.dcisc.org. For further information regarding the public meeting, please contact Robert Rathie, Committee Assistant Legal Counsel, SW 4th & Mission, Suite 2, P.O. Box 4253, Carmel-by-the-Sea, CA 93921-4253; telephone: 1-800-439-4688 or read the agenda on line by visiting the Committee's website at www.dcisc.org.

Dated: February 11, 2024.

Agenda

DCISC Agenda for the next Public Meeting

DIABLO CANYON
INDEPENDENT SAFETY COMMITTEE
(www.dcisc.org)

Committee Members:

Robert J. Budnitz
Peter Lam
Per F. Peterson

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

Wednesday & Thursday, February 21-22, 2024
Point San Luis Conference Facility
Avila Lighthouse Suites
First & San Francisco Streets, Avila Beach, California

PUBLIC MEETING AGENDA

This public meeting will be webcast in real time at:
http://www.slo-span.org/local_webcast/DCISC/stream_index.htm and through https://www.dcisc.org

This meeting is also being produced as a Zoom webinar by AGP Video Inc. and will be broadcast subsequently on San Luis Obispo local government access television, Channel 21.

PARTICIPATION

You may participate in the DCISC's public meeting in person or in real-time by accessing the Zoom webinar meeting via the weblink and the meeting ID and Passcode given above or by calling any of the phone number provided at the top of this agenda. Instructions on how to access, view and participate in remote meetings are also provided by visiting the DCISC's home page at https://www.dcisc.org. Attendees can make oral comments or ask questions of the Committee Members during the webinar meeting by using the "Raise Your Hand" feature or by pressing *9 on your telephone keypad if joining by telephone only. If you are unable to participate in real-time, you may email to dcsafety@dcisc.org with the subject line "Public Comment Item#___" (insert the item number relevant to your comment) or "Public Comment - Non Agenda Item." Comments will be reviewed and distributed before the meeting if received by 5:00 p.m. on Tuesday. February 20, 2024. Comments received after that will be addressed during the item and/or at the end of the meeting. All comments received will be read into and become part of the record, subject to a time limit determined by the presiding officer. Subject to the requirements to publish an agenda in advance, the Committee will have the option to modify its actions on items based on comments received.

In accordance with the Bagley-Keene Open Meeting Act (CA Govt. Code §§11120 et seq.) and the Committee's Policies, for each item on the Agenda the Committee reserves the right, at the discretion of the presiding officer, to limit the total amount of time allocated for public comment on particular issues and/or for each individual speaker.

Morning Session - 02/21/2024 - 9:00 A.M.

I CALL TO ORDER - ROLL CALL

II INTRODUCTIONS AND COMMITTEE MEMBER COMMENTS

ADVISEMENT

The Committee may consider at any time requests to change the order of a listed agenda item. Information distributed to the Committee at a public meeting becomes part of the public record of the DCISC. A copy of written material, pictures, etc., must be provided to the Committee's Legal Counsel for this purpose. Correspondence received and sent by the Committee is on file with the Office of the DCISC Legal Counsel and copies are available upon request. Devices for attendees who may be hearing impaired are available upon request. The meeting will be webcast in real time.

III PUBLIC COMMENTS AND COMMUNICATIONS

Anyone wishing to address the Committee on matters not appearing on the Agenda may do so only at this time. (The public may comment on any matter listed on the morning's Agenda immediately following the time the matter is considered by the Committee.) There may be a time limit for each topic and/or speaker as designated by the presiding officer. No action will be taken by the Committee on matters brought up under this item, but they may be referred to staff for further study, response or action.

IV ACTION ITEM

Receive PG&E's Response to DCISC 33rd Annual Report on the Safety of Diablo Canyon Operations; July 1, 2022 - June 30, 2023.

V ACCEPTANCE OF MINUTES

Minutes of September 13-14, 2023, Public Meeting

VI ACTION ITEM

Review of the Open Items List.

Discussion/Direction

VII COMMITTEE MEMBER REPORTS AND DISCUSSION

Public Outreach, Site Visits and Other Committee Activities; Scheduling and Confirmation of Future Fact-Finding Visits and Public Meetings.Confirmation of Future Fact-Finding Visits and Public Meetings.
Documents Provided to the Committee.

VIII TECHNICAL CONSULTANT REPORTS; RECEIVE, APPROVE AND AUTHORIZE TRANSMITTAL OF FACT-FINDING REPORT TO PG&E

Consultant R. Ferman Wardell: Fact-finding Topics; Report on and Approval of November 14-15, 2023, Fact Finding Report.

IX ADJOURN MORNING MEETING

Afternoon Session - 02/21/2024- 1:15 P.M.

X RECONVENE FOR AFTERNOON MEETING

XI COMMITTEE MEMBER COMMENTS

XII PUBLIC COMMENTS AND COMMUNICATIONS

Anyone wishing to address the Committee on matters not appearing on the Agenda may do so only at this time. (The public may comment on any matter listed on the afternoon's Agenda immediately following the time the matter is considered by the Committee.) There may be a time limit for each topic and/or speaker as designated by the presiding officer. No action will be taken by the Committee on matters brought up under this item, but they may be referred to staff for further study, response or action.

XIII TECHNICAL CONSULTANT REPORT; RECEIVE, APPROVE AND AUTHORIZE TRANSMITTAL OF FACT-FINDING REPORT TO PG&E

Consultant Richard D. McWhorter Jr. Fact-finding Topics; Report on and Approval of the December 12-13, 2023, Fact Finding Report.
Consultant R. Ferman Wardell: Fact-finding Topics; Report on and Approval of January 24-25, 2024, Fact Finding Report.

XIV DISCUSSION, DIRECTION AND ACTION, AS APPROPRIATE, BY THE COMMITTEE, CONSULTANTS & COUNSEL

Status of Governmental Agency Interactions, Responses to SB846 Directives, Administrative, Regulatory, Contractual (Ratify Amendment No. 1 and Consider Approval of Amendment No. 2 to Agreement for Consultant Services with Dr. Mark T. Kirk), Financial and Future Funding Matters, and Other Committee Discussions.
Discussion of New DCISC Initiatives Related to Extended Operations Under SB846, License Renewal, and Changes of Emphasis in Upcoming Fact-Finding Meetings.

XV ADJOURN AFTERNOON MEETING

Evening Session - 02/21/2024 - 5:15 P.M.

XVI RECONVENE FOR EVENING MEETING

XVII COMMITTEE MEMBER COMMENTS

XVIII INFORMATION ITEMS BEFORE THE COMMITTEE

Informational Presentations Requested by the Committee of PG&E:

Briefing on Section 4.2 of New License Renewal Application. (Reactor Vessel Neutron Embrittlement Analysis), Including a Briefing on the Recent Attempt to Retrieve Capsule B on Unit 1

XIX REPORT BY DCISC SPECIAL TECHNICAL CONSULTANT AND DISCUSSION BY THE COMMITTEE & TECHNICAL CONSULTANTS WITH DIRECTION AND/OR ACTION AS APPROPRIATE TO FOLLOW PUBLIC COMMENT PERIOD FOR ITEMS XVIII A.1 &XIX D AS PROVIDED BELOW

Results of Studies by Dr. Mark T. Kirk Evaluating Unit 1 Reactor Pressure Vessel Integrity and Addressing Public Concerns.

XX PUBLIC COMMENTS AND COMMUNICATIONS ON ITEMS XVIII A.1 AND XIX D

Anyone wishing to address the Committee on the above-listed items on the evening's Agenda may do so at this time. There may be a time limit for each topic and/or speaker as designated by the presiding officer.

XXI PUBLIC COMMENTS AND COMMUNICATIONS

Anyone wishing to address the Committee on matters not appearing on this Agenda may do so only at this time. The public may comment on any matter listed on the evening's Agenda as provided above. There may be a time limit for each topic and/or speaker as designated by the presiding officer. No action will be taken by the Committee on matters brought up under this item, but they may be referred to staff for further study, response or action.

XXII ADJOURN EVENING MEETING

Morning Session - 02/22/2024 - 9:00 A.M.

XXIII RECONVENE FOR MORNING MEETING

XXIV COMMITTEE MEMBER COMMENTS

XXV PUBLIC COMMENTS AND COMMUNICATIONS

Anyone wishing to address the Committee on matters not appearing on this Agenda may do so only at this time. (The public may comment on any matter listed on the morning Agenda immediately following the time the matter is considered by the Committee.) There may be a time limit for each topic and/or speaker as designated by the presiding officer. No action will be taken by the Committee on matters brought up under this item, but they may be referred to staff for further study, response or action.

XXVI INFORMATION ITEMS BEFORE THE COMMITTEE (Cont'd.)

Informational Presentations Requested by the Committee of PG&E:

State of the Plant Update including Key Events, Highlights, Maintenance Outage 1X25, Organizational Changes, and Other Station Activities since the DCISC's September 2023 Public Meeting.
Refueling Outage 1R24 Results (Including Initial License Renewal Inspection Results), and Preparation for Refueling Outage 2R24.
Update on the Status of NRC Performance Indicators, Licensee Event Reports, NRC Inspection Reports, NRC Current Issues, and Current and Future License Amendment Requests.
Update on Proposed New Staff Retention Incentive Program in Support of Extended Operations; Results of the 2023 Operating Plan and Key Elements of the 2024 Operating Plan.

XXVII ADJOURN MORNING MEETING

Afternoon Session - 02/22/2024 - 1:15 P.M.

XXVIII RECONVENE FOR AFTERNOON MEETING

XXIX COMMITTEE MEMBER COMMENTS

XXX PUBLIC COMMENTS AND COMMUNICATIONS

Anyone wishing to address the Committee on matters not appearing on this Agenda may do so only at this time. (The public may comment on any matter listed on the afternoon Agenda immediately following the time the matter is considered by the Committee.) There may be a time limit for each topic and/or speaker as designated by the presiding officer. No action will be taken by the Committee on matters brought up under this item but they may be referred to staff for further study, response or action.

XXXI INFORMATION ITEMS BEFORE THE COMMITTEE (Cont'd.)

Informational Presentations Requested by the Committee of PG&E:

Overview of New License Renewal Application Organization, Information Contained and Highlights of Sections with Significant New Information.
Update on the Status of PG&E Sponsored Study Required Under SB 846 for Conducting an Updated Seismic Assessment
Results of Study Required Under SB846 by Independent Consultants to Catalog and Evaluate Any Deferred Maintenance.

XXXII CONCLUDING REMARKS & DISCUSSION BY COMMITTEE MEMBERS OF FUTURE DCISC ACTIVITIES

Future Actions by the Committee.
Further Information to Obtain/Review.
Confirmation of Future Site Visits, and Public Meetings.

XXXIII ADJOURNMENT OF THE ONE HUNDRED AND SEVENTH PUBLIC MEETING

The DCISC's policy is to schedule its public meetings in locations that are accessible to people with disabilities and to remain in compliance with state guidelines on communicable disease prevention. Hand sanitizers and face coverings are available in the meeting room. The Avila Lighthouse Suites Point San Luis Conference Room is a wheelchair accessible facility. A person who needs a disability-related accommodation or modification in order to participate in the meeting may make a request by contacting the DCISC office (in CA 800-439-4688 or (831) 647-1044) or by sending a written request to the DCISC office at P.O. Box 4523, Carmel-by-the-Sea, CA 93921-4523. Providing your request at least five business days before the meeting will help ensure availability of the requested accommodation.

Minutes

M I N U T E S
of the
DIABLO CANYON INDEPENDENT SAFETY COMMITTEE'S
FEBRUARY 21-22, 2024, PUBLIC MEETING
[As Approved at the June 20-21, 2024, Public Meeting.]

Wednesday & Thursday
February 21-22, 2024
Avila Beach, California
Also conducted as a Zoom Webinar

Notice of Meeting.

A legal notice of the public meeting was published in the San Luis Obispo Tribune and a display advertisement was published in the New Times, both local newspapers, and mailed and emailed to the media and those persons on the Committee's mailing list. A mailing list verification form was provided to those persons on the Committee's mailing list in accordance with California Government Code 14911. The meeting agenda and the complete agenda packet for the meeting and the informational presentations made during the meeting together with the fact finding reports to be approved were posted on the Committee's website at prior to the meeting. The meeting agenda contained information on how to access the webinar using a computer, cellphone or a telephone. This in-person meeting was also produced as a Zoom webinar by AGP Video, Inc. and was webcast live on SLO-SPAN at http://www.slo-span.org and through https://www.dcisc.org and was subsequently broadcast on San Luis Obispo, California, local government access television Channel 21. A supply of hand sanitizers and face coverings was made available in the meeting room.

I CALL TO ORDER - ROLL CALL

The February 21, 2024, public meeting of the Diablo Canyon Independent Safety Committee (DCISC), the one hundred and seventh public meeting of the Committee, was called to order by Committee Chair Dr. Peter Lam at 9:00 a.m. Dr. Lam briefly reviewed the professional backgrounds and appointment to the DCISC for each of his fellow Members, Dr. Per F. Peterson, the appointee of the Governor of California and Dr. Robert J. Budnitz, the appointee of the California Attorney General. Dr. Budnitz was in attendance remotely. Dr. Burnitz then briefly reviewed Dr. Lam's professional background and reported Dr. Lam serves on the DCISC as the appointee of the Chair of the California Energy Commission.

Present:

Committee Member Robert J. Budnitz [attending remotely]
Committee Member Peter Lam
Committee Member Per F. Peterson

Absent:

None

A Notice of Remote Participation in this Public Meeting was posted to www.dcisc.org prior to the meeting regarding Dr. Budnitz remote participation.

II INTRODUCTIONS

Dr. Lam introduced and briefly reviewed the professional backgrounds of the Committee's Technical Consultants and Assistant Legal Counsel: Technical Consultants Mr. Richard D. McWhorter Jr., Mr. R. Ferman Wardell, P.E., and Dr. Andrew C. Kadak and DCISC Assistant Legal Counsel Mr. Robert W. Rathie.

Dr. Lam then introduced Mr. Hector M. Garcia, Diablo Canyon Power Plant (DCPP or the plant) Chief Nuclear Officer Support Manager and Ms. Brandy Lopez, Strategic Initiatives Licensing Principal. Dr. Lam remarked Mr. Garcia and Ms. Lopez play key roles on behalf of PG&E and DCPP as liaisons with the DCISC in coordinating the Committee's activities, providing information, and facilitating the Committee's public meetings and the frequent fact-finding visits conducted by a single member and one of the technical consultants.

Mr. Rathie reported this meeting is being livestreamed and broadcast on the internet and he welcomed the technicians for AGP Video who provide this component of the Committee's public meetings.

III PUBLIC COMMENTS AND COMMUNICATIONS

The Chair invited any members of the public who wished to address remarks to the Committee on items not appearing on the agenda for the public meeting to do so at this time.

Dr. Gene Nelson, President and Senior Legal Researcher for Californians for Green Nuclear Power was recognized. Dr. Nelson stated his comments were based upon a message he sent to the Committee earlier in the day with an attachment with an excerpt from Section 4.2 of PG&E's 2023 License Renewal Application. In his message Dr Nelson stated the Committee and the public would benefit from Dr. Mark Kirk, who has been engaged by the Committee to review the integrity of the Unit 1 reactor pressure vessel, analyzing and summarizing Section 4.2 of the Application which Dr. Nelson described as a difficult section to understand, as Dr. Kirk is capable of clearly communicating and focusing on the similarities and differences in the embrittlement determination for Unit 1 as compared to that for Unit 2 and the significance thereof. Dr. Lam thanked Dr. Nelson for his comments.

Dr. Lam requested Mr. Rathie to present the next item.

IV ACTION ITEMS

A. Receive PG&E's Response to DCISC's 33rd Annual Report on Safety of Diablo Canyon Operations: July 1, 2022 - June 30, 2023.

Mr. Rathie reported the Committee approved its 33^rd Annual Report at its public meeting in September 2023 and the report has now been distributed in accordance with the direction of California Senate Bill 846 (SB846)[1] and California Public Resources Code 712.1 which require the Committee to submit its annual reports to the California Public Utilities Commission (CPUC), the California Legislature (Senate and Assembly) and to the NRC as well as to the entities who now receive its annual reports, including PG&E for its response to each annual report which response is once again to be included in each report. Mr. Rathie reported the Committee did not make any recommendations in its 33^rd Annual Report. The Committee publishes its annual reports as two bound volumes, on the internet at www.dcisc.org, in compact disk format and on a USB drive. Annual Reports are also distributed to the Special Collections and Archives Department at the R.E. Kennedy Library at the California Polytechnic University at San Luis Obispo (Cal Poly) and to local public libraries.

On a motion by Dr. Peterson, seconded by Dr. Budnitz, the Committee Members unanimously accepted PG&E's response to the Committee's Thirty-Third Annual Report on the Safety of Diablo Canyon Nuclear Power Plant Operations for the period July 1, 2022 through June 30, 2023. [A prior version of PRC §712.1 did not provide for PG&E's response to be incorporated into the DCISC's annual reports. That provision has been changed and the 33^rd Annual Report now contains PG&E's response to the 33^rd as well as to the 32^nd Annual Report for 2021-2022.

V ACCEPTANCE OF MINUTES

This item concerned review and acceptance of the Minutes of the Committee's September 13-14, 2023, public meeting conducted in Avila Beach and as a Zoom Webinar. A draft of the September 2023 Minutes was included in the public agenda packet for this meeting. Dr. Peterson remarked that the use of bold text in the Minutes is important as it captures and describes some action or commitment on the part of the Committee which is then included on the Committee's Open Items List. The Members and Consultants reviewed the Minutes and provided corrections and substantive changes to certain sections of the Minutes which will be included in the final version of the September 2023 Minutes. The Members and Technical Consultants then conducted a page-by-page review of the September 2023 Minutes and discussed some of the follow-up actions to be taken, provided clarification concerning typographical errors and the accuracy of certain statements in the Minutes and made editorial comments and changes concerning the draft of the September 2023 Minutes.

Mr. John Geesman, representing the Alliance for Nuclear Responsibility was recognized. Mr. Geesman referred to an exchange described on Page 60 of the Minutes wherein Mr. Jearl Strickland, a PG&E Consultant, stated that in a .75G seismic event restoration of operations would occur within the amount of down time expected after a design basis earthquake but Mr. Geesman stated Mr. Strickland did not specify how much time would be allowed for restoration of operation after a design basis earthquake event and Mr. Geesman remarked that if there is such a designated time that it be included in the September Minutes. Consultant McWhorter responded the Committee conducted a fact finding to review the comments made in the report by the Enercon firm concerning movement of the turbines in a design basis earthquake and whether there was the potential for turbine blade damage which Mr. McWhorter remarked could result in a very extended outage. Mr. McWhorter reported that during this fact finding PG&E provided information from the turbine thrust bearing manufacturer that concluded, while the turbine thrust bearing would likely be damaged there were stops that would prevent movement of the turbine shaft such that blade clash would not occur and accordingly the repair time would not be as long as postulated in the Enercon Report. Mr. McWhorter reported he did not recall Mr. Strickland reporting on the anticipated outage duration from a design basis earthquake and this was not covered during the fact finding. Consultant Wardell reported the turbine manufacturer reported it would take several weeks to repair the turbine thrust bearing.

Mr. Geesman remarked he was less focused on the turbine scenario than just generically on the time expected for recovery after a design basis earthquake. Dr. Budnitz stated that after an earthquake that exceeded the operating basis earthquake the plant would be required by its license from the Nuclear Regulatory Commission (NRC) to shut down and perform inspections before it could resume operation. Mr. McWhorter reported this protocol is set forth in NRC Regulatory Guide (RG) 1.166.[2] Dr, Budnitz confirmed it would probably take a period of weeks to accomplish the requirements of RG 1.166.

Consultant McWhorter [who previously served at Old Dominion Electric Cooperative as Vice President of Operations and Asset Management] remarked that when Old Dominion's North Anna Power Station in Virginia experienced an earthquake in 2011 which slightly exceeded the design basis earthquake for that plant, the North Anna plant was offline for approximately 90 days to complete inspections. He reported this was due to the review of the design basis as well as the actual inspections which found very little damage. He confirmed the NRC regulations codify a plant's response to an earthquake larger than the Operating Basis earthquake. Dr. Budnitz observed plants on the East Coast do not experience seismic activity to the degree the West Coast experiences seismic events and as a result DCPP is probably more ready for such a response than a plant located in Virginia as PG&E has an in-house staff and a cadre of engineering personnel who work regularly in the area of seismic risk. Dr. Peterson stated the seismic instrumentation at North Anna was limited due to its data storage capacity and this created a certain level of uncertainty and DCPP has modern instrumentation. Dr. Budnitz reported the NRC has now introduced guidance requiring all nuclear power plants to have better instrumentation than was required prior to the 2011 event at North Anna. Dr. Peterson observed that a lack of adequate instrumentation represents a missed opportunity to confirm the correctness of structural response model predictions. Dr, Budnitz observed that no plant can respond safely to an earthquake unless the operators perform correctly and this was the case in the 2011 event at North Anna during which there were no errors made by the operating crew after the earthquake.

The Minutes of the Committee's public meetings in their final accepted form become part of its Annual Reports. Upon a motion made by Dr. Budnitz, seconded by Dr. Peterson, the Minutes of the Committee's September 13-14, 2023, public meeting were accepted subject to inclusion of the changes provided to the Committee's Assistant Legal Counsel. As revised the September 2023 Minutes will be a part of the Committee's 34th Annual Report.

VI ACTION ITEMS (Cont'd.)

B. Discussion of Issues on Open Items List.

Dr. Lam requested Consultant Wardell lead a review of items on the Open Items List, which he described as an important tool used by the Committee to set priorities, track and to follow issues, concerns, information requests and activities identified for subsequent action or receipt during fact-finding or public meetings. Mr. Wardell stated he appreciated Consultant McWhorter's assistance with the Open Items List and reported newly added or changed items were shown in red italics while items for which follow up is scheduled prior to the June 2024 public meeting were shown in yellow, and items which were deleted or changed were shown in ~~strike-out~~ on the version of the Open Items List included with the agenda packet and certain items on the list were identified for closure.

Items discussed or concerning which action was taken included the following[3]:

Item	Re:	Action Taken/Next Action
CM-13	Rev. Maintenance Dept. Performance	Next Action 3/24 FF (RJB/RDM) Strike 4/24FF Next Action
EN-21	Rev. Projects Long-Term Planning	Next Action after 2R24
NS-5	Monitor NSOC Meetings	Next Action Remote Attendance 10/21/24 & write-up 11/24FF (RJB/RDM)
SC-3	Long-Term Seismic Program	Change ref. to EO-8 to EO-9
SC-14	Monitor IPRP	Next Action 3/24FF (RJB/RDM)
O-3	Nuclear Insurance & Safety Inspections Including Claims Payment History	Next Action 5/24FF (PFP/RDM)
PM 9/23 #5	Circulating Water System/Condensers/Circulating Water System/Condensers/	Circulating Water System/Condensers/
PM 9/23 #8	Artificial Intelligence, Operating Experience & Other Safety-Related Contexts	Next Action 12/24FF (PFP/RFW) and Revise text-delete ref to legal constraints
All Items	Highlight Items Directly Related to SB846 Mandate
February PM	Use of IPAWS	Inquire at next review of EPO

Ms. Linda Seeley representing San Luis Obispo Mothers for Peace (Mothers for Peace) was recognized. Ms. Seeley inquired whether reports on the results of the annual radioactivity release reports could be structured to provide information to the public concerning DCPP releases, including batch releases and their timing as well as liquid and gaseous releases. Mr. Wardell reported the DCISC summarizes these reports every year in its reports of fact-finding on the Committee's review those reports. Ms. Seeley stated her request was for specific information not summaries and she desired explicit information, preferably in advance of any release, as she commented tritium, strontium and cesium accumulate in the human body. Dr. Budnitz reported the DCISC reviewed the reports for 2022 during its August 9-10, 2023 fact finding visit, in Section 3.10 of that report and a report was made to the public at the September 2023 public meeting when the Committee concluded the annual offsite radiological dose received by the general public of less than one millirem was insignificant as compared to the 620 millirem average annual radiation exposure for persons in the United States. Ms. Seeley reported that at the San Onofre Nuclear Generating Station (SONGS) in Southern California the public is now notified before the release of irradiated water. At Dr. Peterson's suggestion a copy of the 2022 reports reviewed by the Committee together with the August 2023 Fact Finding Report will be sent to Ms. Seeley to seek her recommendations for what additional information should be provided.

Dr. Gene Nelson of Californians for Green Nuclear Power was recognized. Dr. Nelson reported he holds a Ph.D. in Radiation Biophysics and he commented Ms. Seeley had made some factual errors in her remarks as there is no mechanism to release strontium or cesium as they are essentially encapsulated in spent nuclear fuel and cesium does not accumulate.

VII COMMITTEE MEMBER REPORTS AND DISCUSSION

A. Public Outreach, Site Visits and Other Committee Activities, Scheduling and Confirmation of Future Fact-Finding Visits and Public Meetings.

Mr. Rathie reported this agenda topic is for Members or Consultants to make a brief report on their activities or site visits since the last public meeting and to then turn to future scheduling of public meetings and fact finding visits.

Dr. Lam reported he held conversations with Ms. Linda Seeley, a member of Mothers for Peace and the PG&E Diablo Canyon Decommissioning Engagement Panel (Engagement Panel), and with Mothers for Peace's attorney Ms. Diane Curran concerning the agenda for this meeting and Dr. Kirk's presentation to the Committee later at this public meeting on his contracted study. Dr. Lam also reported that with Mr. Rathie he participated in a remote interactive meeting with Mr. David Hochschild, the Chair of the California Energy Commission (CEC), the CEC Chief of Staff and Dr. Justin Cochran, CEC Senior Nuclear Policy Advisor and Emergency Coordinator and other CEC personnel to review the Committee's activities in FY 2023/2024 and to discuss the phenomenon of Pressurized Thermal Shock and its related technical and safety implications which he stated was a subject of interest for the CEC representatives.

Dr. Budnitz reported that on several occasions with Mr. Rathie he participated in remote interactive, meetings with representatives of the California Department of Water Resources (DWR) which included Ms. Delphine Hou, Deputy Director Statewide Water and Energy, Messrs. Christian Arechavaleta, Manager Electricity and Strategic Reserve, and Eric Wulff,| Manager, Power Markets Contracts Branch together with DWR Consultants Dr. Deb Luchsinger and Mr. Jerry Bishoff. Dr. Budnitz reported some of these meetings also included Mr. David Zizmor, CPUC Regulatory Analyst, Energy Division. The subject of these meetings included the DCISC's progress in its review of the Updated Seismic Assessment for DCPP which PG&E is required to conduct as a covenant of the loan provided under the provisions of SB846 and which will be subject of a report later during this public meeting.

The Members then discussed and confirmed future public meetings of the DCISC for June 26-27, 2024 [subsequently changed to June 20-21, 2024] and October 9-10, 2024, and February 19-20, 2025 and the Members and Consultants then scheduled a public meeting for June 11-12, 2025.

Fact-finding visits were then confirmed, subject to confirmation by DCPP that the plant can support the visit on the selected dates, and scheduled as follows:[4]

[2024] March 19-20 RJB/RDM; April 17-18 PL/RFW; May 8-9 PFP/RDM; July 31-August 1 PFP/RFW (in conjunction with the next evaluated emergency exercise), August 21-22 PL* or TBD/RDM; September 24-25 RJB/RFW; November 20-21 RJB/RDM; December 11-12 PFP/RFW; and

[2025] January 21-22 TBD/RDM; March 18-19 RJB/RFW; April 8-9 TBD*/RDM; May 7-8 (PFP/RFW).

During the discussion on scheduling Dr Lam announced that he will be leaving his position on the DCISC when his current term concludes on June 30, 3024,* and therefore the August 21-22, 2024 fact-finding visit will likely be conducted by the member appointed by the CEC Chair to serve in his stead. In response to Consultant McWhorter's inquiry Dr. Lam confirmed that should his successor not be timely appointed he would consider continuing to attend fact finding and public meetings if his travel schedule permits until a successor is appointed.

B. Documents Provided to the Committee:

The Chair observed the Committee operates in a transparent fashion. Assistant Legal Counsel Rathie reported outgoing and incoming correspondence to and from the Committee is kept on file at the office of its Legal Counsel and that a list of documents received by the DCISC from PG&E since its last public meeting in September 2023 was included in the public agenda packet for this meeting.

Mr. John Geesman speaking on behalf of the Alliance for Nuclear Responsibility was recognized. Mr. Geesman stated he reported to Mr. Rathie that the log of incoming documents from PG&E does not include the DCISC's receipt of the study by independent consultants required by SB846 to catalog and evaluate maintenance that may have been deferred due to the expectation of the plant closing earlier. Consultant McWhorter reported that this document was put into a separate folder in the Certrec document portal and was not included in the transmittal log. Dr. Budnitz requested Mr. Garcia to check whether the document Mr. Geesman referred to was provided to the DCISC on a confidential basis.[5]

A short break followed.

VIII CONSULTANT REPORT & RECEIVE, APPROVE, AND AUTHORIZE TRANSMITTAL OF A FACT FINDING REPORT TO PG&E

A. The Chair requested Consultant Wardell to provide a summary report on the November 14-15, 2023, fact-finding visit with Dr. Budnitz. Mr. Wardell reviewed the topics discussed with PG&E during the July 2023 visit as follows:

→ Operations Staffing and Retention - Consultant Wardell reported the purpose of this review was related to the potential for extended operation of DCPP through 2030 or perhaps longer and to assess whether a sufficient number of reactor operators were available to safely operate the plant. He reported that because of the success of the two-tiered Employee Retention Program, undertaken following approval of the Joint Proposal,[6] there are a sufficient number of operators presently on staff. DCPP has conducted two new classes for non-licensed operators who perform activities in the plant outside of the control room and Mr. Wardell commented in many cases non-licensed operators go on to obtain licenses as reactor operators.[7] Another non-licensed class is being planned together with license upgrade classes. The Fact Finding Team (FFT) concluded operator staffing is satisfactory to safely continue operations.

→ Unit 1 Vessel Embrittlement – Mr. Wardell stated Dr. Mark Kirk who has been engaged by the DCISC as a technical consultant to review this topic will make a presentation later during this meeting and the purpose of the fact finding was to address nine technical questions. Dr. Kirk attended the fact finding as did representatives of DWR and the FFT received satisfactory answers to Dr. Kirk's questions.

→ NRC Maintenance Rule[8] Update – The purpose of this FFT inquiry was to assess the health and effectiveness of the Maintenance Rule Program at DCPP which monitors the maintenance of systems, structures and components (SSC) based on their risk significance. Problems are assessed to be determine if they represent maintenance preventable functional failures and affected SSCs are placed into (a)(1) status in the Maintenance Rule Program for correction and subsequent monitoring. Mr. Wardell reported the number of SSCs in (a)(1) status at DCPP has been declining as has the number of maintenance preventable functional failures and the FFT concluded the DCPP Maintenance Rule Program is healthy and effective.

→ Probabilistic Risk Assessment (PRA) Analysis Update – Dr. Budnitz explained the purpose of a PRA is to calculate the core damage frequency and the frequency of a very large early release of radioactivity by identifying every important accident sequence and for each of those sequences working out the likelihood of occurrence and its consequences. Over a period of years the community of PRA experts have developed a confidence that all the accident sequences for a plant such as DCPP have been identified. He reported the PRA for DCPP is considered among the best and careful work continues for improving the analyses and to reduce uncertainties. Dr. Budnitz commented the DCPP Seismic PRA is judged to be the finest in existence and it serves as a model for other plants. Every plant is required to periodically update its PRA and DCPP performed a full update with outside expert peer review which was completed in April 2023. He reported this update included accounting for changes to plant procedures and design changes. Dr. Budnitz reported the plant PRA is now up to date and is used for assessing safety in decision making, including determining the extent of the safety compromise when a piece of equipment is taken out or service or begins to age and whether work should be performed on equipment while the plant is online or during an outage. The PRA is also used in the license renewal process. Dr. Budnitz reported the FFT concluded not only is the DCPP PRA excellent, but it is also proving its effectiveness as a decision making tool.

→ Meeting with Nuclear Regulatory Commission (NRC) Resident Inspector – Mr. Wardell reported the FFT met with NRC Resident Inspector, Ms. Ayesha Athar, to discuss the Preventative Maintenance Optimization ++ Program (PMO++),[9] the twenty-third refueling outage for Unit 1 (1R23), recent NRC inspection activities and the DCPP License Renewal Application. Mr. Wardell stated the FFT concluded the meetings with the NRC on site resident inspectors are beneficial. Mr. Wardell reported the Resident Inspector, one inspector of a two-inspector team, will soon be reassigned by the NRC.

→ Institute of Nuclear Power Operations (INPO) Update – Consultant Wardell reported discussions concerning INPO, which sets high standards for the industry to improve performance and conducts evaluations every other year for every plant in the United States are restricted by confidentiality agreement. INPO also provides operating experience to plants and assists with plant programs. Concerns raised by INPO evaluations are addressed through the plant's Corrective Action Program. Mr. Wardell stated he was able to report DCPP regularly receives positive evaluation results from INPO, but due to the confidentiality restrictions he could not discuss any details.

→ Meet with DCPP Officer – the FFT met with Vice President of Technical and Business Services Ms. Maureen Zawalick to discuss items on the fact finding agenda and other items of mutual interest. Mr. Wardell report these meetings with DCPP leadership continue to be beneficial.

→ Independent Seismic Update – Dr. Budnitz reported the FFT reviewed three different activities related to seismic assessments. The first activity was in connection with the updated seismic assessment required by SB846 which Dr. Budnitz commented the DCISC is still reviewing and on which there will be a report later in this meeting. The second activity concerned the reviews of DCPP seismic safety conducted by the CPUC's Independent Peer Review Panel, made up of certain state governmental entities, and the IPRP's upcoming meeting expected to be held in April or May 2024 and the IPRP's review of the PG&E Updated Seismic Assessment mandated by SB846. Finally, Dr. Budnitz observed PG&E has submitted a License Renewal Application for DCPP which includes sections concerning seismic safety which the DCISC will also review. He observed the plan is now to revisit the Committee's May 5, 2023 evaluation and to make a further report at the June 2024 public meeting.

→ Refueling Outage 1R24 Update and Outage Control Center – Mr. Wardell reported at the time of the FFT visit Unit 1 was connected to the grid and was in the process of increasing power and was at the point where testing was required to include chemistry sampling and checking for condenser and other salt water leakage and operators were awaiting instruction from the Reactor Engineering Department. Consultant Wardell reported 1R24 was judged successful and to have met its goals with the exception of the collective radiation dose goal having been exceeded due to the impact of emergent work. [Subsequently, during the presentation on the December 2023 fact-finding visit it was reported that this emergent work was caused by a small leak on a pressurizer safety valve.] Dr. Budnitz remarked that while the outage goal was exceeded the collective radiation dose for 1R24 remained well within regulatory guidance and no single individual received anything approaching the individual radiation dose limit.

→ Independent Assessment of Maintenance – Consultant Wardell reported this assessment was required by SB846 and was performed by the W.M. Dean Consulting Company during April through October 2023. The FFT together with DWR representatives reviewed the consultants' report which concluded DCPP has not experienced any deferred maintenance that would create a vulnerability to future plant operations or warrant remedial action. The DCISC FFT reached a similar conclusion and found the assessment to have been extensive and quite intrusive.

→ Accompany Operator on Unit 2 Rounds – Mr. Wardell reported the FFT accompanied an operator on rounds in the plant and visited areas in the Turbine and Auxiliary Buildings including observation of the condensers and the feedwater pumps located above the condensers. He reported the operator was knowledgeable concerning the components visited and in use of the checklist, and the FFT found the plant to be clean and orderly with the equipment operating normally.

→ Observe Nuclear Safety Oversight Committee (NSOC) Meeting (11/20/23) – Consultant Wardell reported the NSOC is comprised of five high level executive external industry peers who visit the site over four-day periods to provide a thorough, comprehensive and candid independent perspective on plant safety and performance. For reasons of confidentiality Mr. Wardell stated he could not describe the particulars of the NSOC's visit which concluded with the exit meeting held on November 20, 2023, which the FFT was allowed to attend remotely.

Mr. John Geesman representing the Alliance for Nuclear Responsibility inquired concerning the PRA whether his understanding was correct that the term "risk significance" as used in context of a PRA is quantitatively determined by two criteria, those being contribution to core damage frequency and contribution to large early release frequency. Dr. Budnitz replied those are the criteria upon which the NRC concentrates but there are others including whether a large release will be early or later in a PRA scenario and the NRC's concentration is on scenarios leading to an early release.

In response to Mr. Geesman's inquiry, Dr. Budnitz stated that while plant reliability is not one of the NRC's PRA criteria, the plant does pay attention to scenarios affecting reliability which are revealed by PRA analyses, whereby a combination of failures or human error would lead to a compromise of reliability and the plant uses the PRA to prioritize maintenance, replacement, and repair as well as operator training. Dr. Budnitz stated he believes that where the fact finding report addresses online maintenance review, plant reliability is not one of the considerations for measuring risk significance. Dr. Peterson observed the plant has identified all of the single point vulnerabilities that can cause a reactor trip[10] and the identification of single point vulnerabilities is more directly related to plant reliability and there are programs to ensure those items which represent single point vulnerabilities have high reliability. Dr. Budnitz replied the PRA identifies those sequences and when concern is expressed with a particular function or item the PRA group is consulted to determine a components role in the PRA.

In response to Mr. Geesman's inquiry about the SB846 Independent Review of Deferred Maintenance not being included in the document list for this meeting Mr. Wardell confirmed the report was included with the electronic work package received from PG&E, but as it was not part of the regular document transmittal it was omitted from the list. In response to Mr. Geesman's observation that some years ago DCPP did receive a downgrade in its rating from INPO, Mr. Wardell stated he believes Mr. Geesman's observation is correct, after which efforts were made to restore the plant's INPO rating.

Mr. David Weisman representing the Alliance for Nuclear Responsibility was recognized. He stated concerning the failure during 1R24 to meet the goal for collective radiation exposure there was reference to emergent issues and he inquired as to a more detailed enumeration of what those emergent issues may have been. Mr. Wardell stated he would review the written report and provide more information to Mr. Weisman later during the meeting, as there is a presentation scheduled during this meeting on the 1R24[11] refueling outage and that may be an opportune time to address Mr. Weisman's inquiry. Dr. Budnitz and Mr. Garcia replied it was not uncommon for things to be discovered during a refueling outage that were not expected during the outage planning process. Mr. Garcia observed that when outage goals are set, they are often revised and made more aggressive based upon performance during the outage.

Mr. Rathie suggested the Committee follow its recent practice of approving its fact finding reports by resolution. On a motion by Dr. Peterson seconded by Dr. Budnitz the November 14-15 & 20, 2023 Fact Finding Report, together with Resolution 2024-01, was unanimously approved. Mr. Rathie reported all the fact finding reports to be considered at this public meeting were made available on the Committee's website at www.dcisc.org prior to the meeting.

IX ADJOURN MORNING MEETING

The Chair adjourned the morning meeting of the DCISC at Noon.

X RECONVENE FOR AFTERNOON MEETING

The afternoon meeting of the DCISC was convened by the Chair at 1:20 p.m.

XI COMMITTEE MEMBER COMMENTS

There were no comments by any member at this time.

XII PUBLIC COMMENTS AND COMMUNICATIONS

Dr. Lam invited members of the public to address the Committee on matters not on the agenda for this meeting.

Mr. Elliot Korb was recognized and stated he was with the Radiant Nuclear firm. [Radiant Nuclear has designed a fission microreactor that's fueled by ceramic-coated particles of high-assay, low-enriched uranium and cooled by helium gas.] Mr. Korb inquired concerning the availability of any upcoming tours of DCPP. Dr. Peterson remarked that in the past the Committee regularly conducted tours with members of the public as part of its mandate to conduct public outreach and the Members and Consultants briefly discussed again offering tours in connection with upcoming DCISC public meetings. Mr. Garcia reported PG&E presently conducts tours and Mr. Rathie stated that when requests are received through the Committee's office a DCPP representative [Ms. Rachel Dion] has been extremely helpful and responsive in facilitating those requests. At Dr. Budnitz' request Mr. Korb provided his contact information through the Committee's website. [Mr. Korb was subsequently provided information to the Committee's office and was contacted by Ms. Dion concerning a tour.]

Dr. Gene Nelson of Californians for Green Nuclear Power reported the link to plant operation information on www.dcisc.org was not working nor was the direct line to access a recording on plant operating status. Mr. Rathie reported he would consult with the Committee's webmaster to see if something can be done or have the link removed.

XIII CONSULTANT REPORT & RECEIVE, APPROVE, AND AUTHORIZE TRANSMITTAL OF A FACT FINDING REPORT TO PG&E

B. The Chair requested Consultant McWhorter to provide a summary report on the December 12-13, 2023, fact-finding visit with Dr. Peterson. Mr. McWhorter reviewed the topics discussed with PG&E during the December 2023 visit as follows:

→ Refueling Outage 1R24 Results – Consultant McWhorter reported DWR representatives joined remotely with the DCISC Fact Finding Team (FFT) for this topic. He reported 1R24 began on October 1 and ended November 13, 2023 and in general all major work activities were completed as planned including all license renewal inspections which represented a very large scope of work. With the exception of collective dose, reviewed previously, and reliability all outage goals were met. The goal for reliability was not met due to failure to operate Unit 1 for 90 consecutive days following startup due to a shutdown at day 26 [outage 1X25] to repair a small leak on a pressurizer safety valve. The FFT concluded 1R24 was successful and the DCISC should follow up on the causes and corrective actions for the pressurizer safety valve leak and on forced maintenance outage 1X25.

→ Outage Management Team Meeting – Mr. McWhorter reported this is a meeting of senior leadership at the station to review different aspects of outage preparation and management including review of 2R24, focusing on deferring laser mapping of the Unit 2 high pressure turbine in preparation for its replacement in 2R25, and the removal from 2R24's scope of a modification to the temporary reactor vessel cavity seal in order to free up resources for other work. The FFT concluded the Outage Management Team meeting was conducted efficiently and effectively.

→ Response to DCISC Recommendation on the Use of Earthquake Response Procedures – This recommendation was made in the DCISC July 2023 Fact Finding Report regarding the use of FLEX[12] procedures. Mr. McWhorter reported FLEX procedures would typically be entered into upon extended loss of all alternating current (AC) power at the station. During the July 2023 fact finding the DCISC FFT recommended that DCPP assess what might trigger consideration of the use of FLEX in situations involving an earthquake. Mr. McWhorter reported the DCPP Operations Department has made changes to earthquake response procedure CP M-4 in response to the DCISC's recommendation and he reported other departments were currently reviewing procedures specifically in the areas of emergency preparedness and stranded plant procedures and in security for post-earthquake inspections. The DCISC FFT concluded that this was appropriate follow up and the status of the implementation of FLEX procedures for post-earthquake response should be reviewed in the future with reference to other procedural changes.

In response to Consultant Kadak's request Mr. McWhorter summarized the changes related to FLEX to Operations procedure CP M-4 as including checking the status of the spent fuel pools and referring to FLEX procedures to mitigate damage to spent fuel if needed, checking site conditions to ascertain if FLEX implementation strategies need to be implemented such as ensuring routes to access FLEX equipment are clear, using FLEX procedures to assess plant damage during walkdowns and using FLEX communication equipment if plant communication is lost post-earthquake.

→ Training Program for New Engineers – Mr. McWhorter reported 48 new engineers were hired last year bringing the total for the Engineering Department to 127 engineers. He commented many of the new engineers had prior experience and the FFT found training for the new engineers is conducted in three stages: engineering support personnel initial training; a ten-week INPO-accredited training program an individual position specific qualifications plan to be completed in one year; and individual development plans focused on development of additional skills for current and future assignments. Mr. McWhorter reported DCPP has engaged a consultant to facilitate coordination of knowledge transfer to oversee the transfer of position-specific knowledge between engineers. The FFT concluded the training for new engineers was well organized and appropriately focused to maintain the technical knowledge in the Engineering Department.

→ Intake Cove Maintenance and Dredging Project Update – Consultant McWhorter stated this review was brought to the Committee's attention by an anonymous message which was mailed to the Alliance for Nuclear Responsibility and provided to the DCISC by the Alliance. The author of the message alleged improper deferral of the dredging project and improper cleaning of the intake area by divers. The FFT first inquired of PG&E concerning these topics without revealing the existence of the message and learned the dredging project was deferred from refueling outage 1R24 to 2R24 primarily due to the complexity of contracting and permitting requirements and not by financial concerns. He reported the DCISC representatives learned that divers routinely use fire hoses to clean areas around the Intake Structure for safety reasons and in this activity some amount of sand is pushed through the system to clear the area so the divers can inspect the bar racks and traveling screens at the Intake Structure for corrosion and other problems. The FFT learned sand is swept through the system on a regular basis and this is not precluded by the environmental permit.

Consultant McWhorter reported the FFT subsequently revealed the existence of the anonymous message to PG&E and it was entered into the Employee Concerns Program for further review. He reported the DCISC then followed up on the investigation by the Employee Concerns Program at the January 2024 fact finding to see if other concerns had been expressed and to review the independent evaluation by the Employee Concerns Program. The FFT concluded the dredging project was being appropriately managed and the maintenance activities in the Intake Cove by the divers were appropriate.

→ Unit 1 Reactor Vessel Embrittlement Update Including Efforts to Remove Capsule B -During the fact finding Committee Consultant Dr. Mark Kirk was provided an opportunity to ask questions of PG&E relative to the report Dr. Kirk has prepared on this topic. Representatives of DWR participated remotely in this session as did Consultants Kadak and Kirk. Two specific areas were reviewed including the history and results of the Unit 1 reactor pressure vessel 10-Year In-Service Inspection Program to conduct a non-destructive inspection of welds. Mr. McWhorter reported a partial inspection was conducted in 2024 and the next inspection is currently scheduled for 2025 during 1R25 at the time of removal of the Unit 1 reactor core barrel. The FFT also received a briefing on the prior unsuccessful attempts to remove surveillance Capsule B from Unit 1 and the inability to engage the tool with the capsule plug. Mr. McWhorter reported the DCISC and the public will receive information on this matter during the evening presentation and the FFT concluded DCPP had provided adequate information on past Unit 1 pressure vessel weld inspection results, together with answers to questions raised related to vessel embrittlement.

→ Refueling Outage 1R24 License Renewal Inspection Results – Consultant McWhorter reported there were approximately 184 license renewal inspections completed for Unit 1 during refueling outage 1R24 including inspections of welds, of small bore piping, internals of various tanks including Refueling Water, Diesel Fuel and Condensate Storage Tanks, concrete inspections, and electrical and cable inspections. He reported during 1R24 approximately 35 components were removed from service and replaced with new components. Mr. McWhorter reported the FFT found overall that the results from 1R24 were very positive with no age-related challenges identified to any system's ability to perform its function. The DCISC FFT also discussed the results of the 1R24 inspections conducted by the NRC inspectors which identified no concerns with any of the license renewal inspection activities for Unit 1. There was one non-cited violation (NCV) for an issue on Unit 2 related to sealing of a joint in Containment but this was unrelated to inspection for license renewal.

→ License Renewal Application Overview – Mr. McWhorter reported representatives of the DWR attended this session remotely. He reported the purpose of license renewal is not to re-validate the safety design of the station, but to validate that aging will not impact safety functions during an additional twenty years of operation. The scope includes identifying which systems are subject to Aging Management Programs and to identify specific types of aging mechanisms. Consultant McWhorter observed there are 44 Aging Management Plans applicable to DCPP for this initial and for the ongoing rounds of inspections. He observed that out of the approximately 3,000 pages that make up the DCPP License Renewal Application approximately 1,000 pages consist of the Environmental Impact Report. He reported that the day after the FFT met with DCPP representatives the License Renewal Application was deemed sufficient and was accepted by the NRC which action allows the station to continue to operate beyond the end of its current operating licenses while the License Renewal Application continues to be reviewed by the NRC.

→ Update on the Use of Electronic Procedures – Mr. McWhorter reported this topic was a follow up to discussions at a prior public meeting and included a dialogue with DCPP concerning incorporating new technologies such as electronic procedures. He reported DCPP expressed that it is now focused on getting through the current license renewal application process and the outage work required, but DCPP does have a desire to be more proactive in this area in the future. Mr. McWhorter stated the FFT concluded that the DCISC should review the topic of electronic procedures following conclusion of the 2R24 refueling outage.

→ Management Observation Programs – Mr. McWhorter reported this program has expanded and is the subject of regular DCISC review. He reported the program provides for supervisors to regularly observe employees while the employees work in the plant and these observations are discussed in a collaborative fashion with the data entered into an electronic system to track and categorize and to assess any developing trends across the station. Between September to mid-December 2023 there were 1,246 observations made including during 1R24 and a number of strengths as well as some opportunities for improvement were identified. Consultant McWhorter reported in response to the FFT's inquiry as to the employees' perception of this observation program the DCPP representatives responded employees generally feel it is a normal part of the business of operating a nuclear power plant. In response to Consultant Kadak's query Mr. McWhorter replied these observations include looking for the use of human performance tools, compliance with plant procedures, and the use of personal protective equipment by Operations and Maintenance Department personnel. He reported of the 1,246 observations perhaps 100 were written up as strengths and approximately 150 represented opportunities for coaching on procedures. The FFT concluded the observations appear to provide valuable insight into human performance strengths, weaknesses and opportunities at the station.

→ Emergency Preparedness Department – Consultant McWhorter reported this was a routine review but the timing was important due to an issue within the last two years with drill performance and a drill and graded emergency exercise are both scheduled for the middle of 2024. The Emergency Preparedness Department manages training for the groups and employees that staff the emergency response facilities. Staffing consists of four Emergency Response Teams with approximately 70 individuals on each team who serve on-call for two weeks on a rotating basis. The teams have drills scheduled consisting of exercises for the entire station and for individual teams and work groups. In past years deficiencies were noted with attendance and performance during drills and Mr. McWhorter reported the FFT found the numbers of such deficiencies have been reduced significantly and this issue seems to be resolved with appropriate corrective actions having been taken with the use of dynamic learning activities in the training exercises. Consultant McWhorter reported the Emergency Preparedness Department has increased staffing and now consists of seven persons and one supervisor. The FFT also discussed the implementation of a new emergency siren test protocol using electronic equipment to sense activation. The FFT concluded the Emergency Preparedness Department was performing well overall and the DCISC should plan to observe the emergency preparedness exercise scheduled for July 31, 2024 and Mr. McWhorter reported a fact finding visit has been planned around that date.

→ Meet with DCPP Officer –The FFT met with Vice President of Business and Technical Services Ms. Maureen Zawalick to discuss items of mutual interest.

→ Auxiliary Saltwater Pump 2-2 Degradation and Exigent Technical Specification[13] Change – Mr. McWhorter reported DCPP applied for an exigent Technical Specification (TS) change for an extension of the outage time to perform a motor replacement for auxiliary saltwater pump 2-2 from 72 to 144 hours. The problem with the pump involved increasing degradation of the oil for the pump motor due to the presence of iron which was indicative of possible bearing wear. Consultant McWhorter reported the decision to replace the pump motor prior to the next scheduled refueling outage was conservative and a prompt operability assessment (POA) was performed to document that the pump could still perform its safety function until the motor could be replaced. He reported it took 84 hours out of the 144 hours allowed by the TS change to compete the work. A cause evaluation will be performed for the bearing degradation and Consultant McWhorter reported the FFT recommended the DCISC review the cause evaluation in the future. The FFT concluded there were no safety concerns. Consultant McWhorter reported there is presently an effort to transition to risk-informed outage times under a future license amendment request that would allow the use of PRA insights, the employment of compensatory actions to reduce the risk, and the protection of alternative components to allow a plant to determine on its own whether additional outage time might be allowed. Dr. Budnitz remarked the NRC Reg. Guide 1.174 addresses use of PRA.

→ Low Temperature Overpressurization Protection (LTOP) System – Consultant McWhorter reported the DCISC chose to examine the LTOP System in context of the concerns expressed concerning the phenomenon of Pressurized Thermal Shock (PTS). He reported there are basically two broad situations where PTS is an issue: over pressurization of the Reactor Coolant System (RCS) when it is at low temperature during shutdown conditions; and in the specific situation where cold water is injected at high pressure into the reactor by the Emergency Core Cooling System (ECCS). He remarked it is the low temperature shutdown situation where a plant is most vulnerable to PTS. The LTOP System is designed to prevent that situation by measuring and monitoring the RCS pressure when the temperature of the plant is low and then opening two power-operated relief valves if necessary to vent pressure. The LTOP System is enabled at low RCS temperatures and the set points and temperature limits and the allowed equipment configuration are all established by a pressure and temperature limits report. He reported part of the analysis that goes into determination of the set points for DCPP includes evaluating a hypothetical pre-existing crack in the reactor vessel of 2" deep by 12" long. The FFT concluded the station appropriately uses the LTOP System to prevent inadvertent over pressurization of the reactor vessel at low temperatures.

In response to Consultant Wardell's inquiry Mr. McWhorter replied the LTOP System can act rapidly and has sufficient capacity to prevent PTS when the plant is shut down there are certain pieces of equipment that must be taken out of service in accordance with Technical Specifications including some of the high pressure safety injection pumps and if that is done then if the remaining pumps and systems were to start and inject water then the power-operated relief valves would relieve that amount of flow and prevent pressure from reaching the point where the vessel could crack, given the assumed hypothetical 2" by 12" pre-existing crack and the LTOP System would have the capacity to prevent PTS. Mr. Wardell commented on the importance of the LTOP System to prevent or mitigate an over-pressure event.

→ Meet with Nuclear Regulatory Commission (NRC) Senior Resident Inspector – Mr. McWhorter reported the FFT met with Senior Resident Inspector Mr. Mahdi Hayes to discuss the topics from the fact-finding visit and other topics of mutual interest.

After Mr. McWhorter's presentation Mr. John Geesman representing the Alliance for Nuclear Responsibility was recognized. Mr. Geesman inquired as to the inspections of the Unit 2 high pressure turbine being deferred from the 2R24 outage pending a risk review by DCPP's insurer based on the fact-finding report itself. Mr. Geesman inquired as to what firm acts as the insurer and how often does an insurance review occur in outage planning. Consultant McWhorter responded he believes the insurer was involved because the insurer is aware the Unit 2 turbine is old and has been monitoring the situation. He observed this does not significantly change the timetable for replacement of the turbine it just moves pre-inspection work from one outage to another.

Mr. Geesman then inquired regarding use of an integrated public alert warning system (IPAWS) which uses cellular phone notifications. He stated IPAWS has been used within the nuclear industry and inquired whether the Committee or the FFT had a view as to whether DCPP should implement such a system rather than relying on sirens. Consultant McWhorter confirmed that many plants have transitioned to the use of IPAWS warning systems but it is his understanding that PG&E is not considering implementing IPAWS at this time but has not ruled it out as a backup means of notification to alerting the public regarding safe routes but any such implementation would need to be done in conjunction with state and local officials. Dr. Budnitz suggested the DCISC's next review of the Emergency Preparedness Program should include asking DCPP about plans to use IPAWS and the rationale for continued use of the present system of notification. [Added to Open Items List.]

Ms. Sherry Lewis, a member of Mothers for Peace, was recognized. In response to Ms. Lewis' inquiry regarding aging evaluations performed as part of the license renewal process Mr. McWhorter replied that because the plant's basic safety design has not changed there is no need to validate the design, but components are reviewed and the purpose of the license renewal inspection scoping efforts is to review all installed equipment and identify all possible aging mechanisms that need to be addressed by Aging Management Plans. Dr. Budnitz remarked only the items kept in the scope are those components for which aging is thought to be important and the DCISC reviewed the list of items retained within the scope and also confirmed items screened out of the scope were not age-related. Dr. Lam remarked that previously it was required during a licensing hearing to examine anything safety-related but the NRC has now changed that approach to focus litigation only on equipment related to aging.

Mr. Bruce Severance was recognized. In response to Mr. Severance's questions related the automatic controls of pressure temperature limits Mr. McWhorter replied procedures and technical specification exist to control the configuration of equipment as the plant shuts down and an annunciator alerts the operators once the temperature drops below a certain level to place the LTOP System in service. Mr. McWhorter, in response to Mr. Severance's inquiry concerning a loss of coolant accident (LOCA), replied a LOCA is not the scenario the LTOP System is designed to protect against. He commented that to have a LOCA and have the temperature in the reactor vessel fall and then to have high pressure water injected into the vessel is a very difficult accident sequence to generate. In response to Mr. Severance's comment about controlling a curve which describes the increase in pressure following activation of the Emergency Core Cooling System (ECCS) which Mr. Severance stated could lead to PTS, Dr. Peterson observed a reactor cannot be operating at power and be at a low temperature and in the situation described by Consultant McWhorter's report, as the reactor is not operating at power it does not have a substantial inventory of fission products present releasing heat and the Residual Heat Removal (RHR) System is capable of low pressure injection. Consultant McWhorter observed in a LOCA situation pressure is dropping in a reactor which is shut down but where the vessel remains at a high temperature and as the vessel is refilled procedures call for shutdown of some pumps, The reactor does not get into a cold over-pressurization situation and the goal is to activate the RHR System in a low pressure recirculation mode with that system's available relief valves. In response to Mr. Severance question Mr. McWhorter replied that the water used in the ECCS is not pre-heated. Dr. Lam remarked there are good sources of information on the emergency core cooling features about which Mr. Severance has inquired in 10 Code of Federal Regulations (CFR) Appendix K of the NRC regulations, together with the DCPP Final Safety Analysis Report (FSAR). Dr. Budnitz commented there is also some training material for reactor operators which is in the public domain and Dr. Lam remarked the NRC has a generic training manual available to the public.

Dr. Gene Nelson of Californians for Green Nuclear Power was recognized and he referred Mr. Severance to the reports that were issued after the accident in 1979 to Unit 2 at the Three Mile Island Nuclear Generating Station in Pennsylvania.

On a motion by Dr. Budnitz seconded by Dr. Lam the December 12-13, 2023 Fact Finding Report, together with Resolution 2024-02, was unanimously approved.

C. The Chair requested Consultant Wardell to provide a summary report on the January 24-25, 2024, fact-finding visit with Dr. Lam. Mr. Wardell reviewed the topics discussed with PG&E during the January 2024 visit as follows:

→ Observe Plant Health Committee Meeting – Consultant Wardell reported that due to a conflicting emergency exercise the Plant Health Committee observation was cancelled.

→ 2R24 Refueling Outage Plans - Mr. Wardell reported the outage scope for 2R24 is similar to that for 1R24 and the 2R24 outage is planned to take approximately 50 days including the license renewal inspections. He reported the outage goals include no recordable injuries, no nuclear safety events and a radiation dose goal that has yet to be established. The FFT concluded the outage plans for 2R24 appeared appropriate.

→ Meet with NRC Senior Resident Inspector – the FFT met with Senior NRC Resident Mr. Mahdi Hayes to discuss the NRC's inspection activities and the refueling outages for Unit 1 and Unit 2. Mr. Wardell reported the Resident Inspector, Ms. Ayesha Athar, is to be reassigned soon. He reported there are three NCVs to be documented in the next inspection report including an allegation raised concerning a leak on an emergency diesel generator fuel tank which the NRC investigated and found not to be of concern. The FFT concluded the meetings with the NRC resident staff are beneficial.

→ 2023 Operating Plan Results and 2024 Operating Plan –Mr. Wardell reported there will be a presentation by PG&E later during this public meeting and he commented all goals from the 2023 Operating Plan were met with the exception of the Occupational Safety and Health Administration (OSHA) related goal to have no recordable injuries, as there was one such injury during 2023. Consultant Wardell briefly reported the Operating Plan goals for 2024 are similar to those for 2023.

→ Unit 1 Reactor Vessel Embrittlement - Mr. Wardell reported this session of the fact finding visit was attended remotely by DWR representatives. The purpose was to provide PG&E with an opportunity to review Dr. Mark Kirk's reports on the integrity of the Unit-1 reactor pressure vessel for factual error or omission. He reported PG&E representatives identified minor corrections which Dr. Kirk has made and which did not affect the results of the reports.

→ 2024 Spent Fuel Loading Campaigns – Mr. Wardell reported a campaign constitutes moving spent fuel assemblies from the spent fuel pool to the Independent Spent Fuel Storage Installation (ISFSI) located on the hillside behind and above the plant. There have been no loading campaigns conducted since 2018 and for 2024 six loading campaigns are planned for each unit, for a total of 384 fuel assemblies with 32 assemblies placed in each multipurpose cannister which is then placed into an overpack. Mr. Wardell reported training has been conducted by the Holtec firm which manufactures the casks to be used and procedures and processes have been improved for the upcoming loading campaigns. Consultant Wardell reported the spent fuel dry storge system manufactured by the Orano firm is expected to be available for use in 2030 after completion of its site-specific seismic qualification for DCPP. The FFT concluded the spent fuel loading campaigns are being appropriately planned. Dr. Lam mentioned that with the expedited process employed by DCPP to obtain casks from the Holtec firm there is no delay in the process.

→ 2023 Regulatory Year in Review - Mr. Wardell reported that in 2023 the NRC spent 5,600 hours in inspection activities and issued 11 NCVs. The 16 NRC Performance Indicators remained in all "Green" status[14] and License Amendment Requests (LARs) have been submitted for risk informed completion times as described by Mr. McWhorter during his presentation and for license renewal. Mr. Wardell reported the NRC has now accepted the License Renewal Application.

→ Post-Outage 1R24 Reactor Physics Test – Consultant Wardell reported that following 1R24, nuclear core physics testing was performed as power was increased to assess the fuel's design, as one third of the fuel assemblies are normally replaced in each refueling outage, and to test the accuracy of predictions and analyses integral to power operation. Included is the measurement of control rod worth to ensure the control rods can shut down the power plant. Subcritical negative reactivity and moderator temperature coefficient to keep the core safe were also tested. Mr. Wardell reported a new physics test, called the alternate rod worth test, was used after 1R24 and he reported this test has a lower risk than previous test protocols due to fewer movement of the control rods and also has the benefit of saving six to eight hours of outage startup time. He reported the FFT was impressed with the improved reactor physics testing.

→ Intake Dredging Update – Mr. Wardell reported the FFT conducted a follow up from the December 2023 fact-finding visit concerning this item and learned the Employee Concerns Program did not find an allegation having been independently raised regarding dredging at the Intake Structure or concerning retaliation for raising that matter. Dr. Lam commented DCPP took this matter very seriously and used its normal process to investigate with no effort or attempt at retaliation discovered. Mr. Wardell and Dr. Peterson observed that as the allegation was raised anonymously with the Alliance for Nuclear Responsibility it was impossible to trace the source. Dr. Lam observed if dredging were not done this would not be a major safety concern. Consultant McWhorter remarked the accumulation of sand in front of the Intake Structure occurs more in the area of the circulating water pumps than in proximity to the safety-related auxiliary saltwater pumps. Dr. Peterson observed there are benefits to dredging to reduce the velocity of water flows and reduce entrainment of kelp.

→ Observe Reactor Operator Continuing Training on the Simulator – Mr. Wardell reported the FFT observed reactor operator training in the Simulator Facility.[15] Mr. Wardell reported the drill postulated a faulty steam generator with a steam and hot water leak inside Containment with a resulting LOCA and loss of cooling. The DCISC team observed the training and Mr. Wardell reported the Simulator performed perfectly and the Operations crew performed very well over the several hours of training. He reported the Operations crew used proper human performance tools and the training was successfully completed.

→ Air- and Motor-Operated Valve Programs – Consultant Wardell reported this was a periodic review for the DCISC of formal programs on procedures which test safety-related valves periodically, generally during an outage. The valves are tested to ensure they are capable of opening or closing on time and for any friction in the valve stem to assure they will operate properly under normal or accident conditions. The FFT concluded the Air and Motor Operated Valve Program is in good health with any valve found to be out of specification placed immediately into the Corrective Action Program.

→ Emergency Diesel Generator (EDG) Update – The FFT reviewed EDGs and visited the Turbine Building and toured EDG 1-2 with the system engineer. Health status for the EDGs for both Units is Green and Mr. Wardell reported the system engineer is very knowledgeable and the plant was found to be good and clean condition. The EDGs are at present all within specifications.

Mr. John Geesman representing the Alliance for Nuclear Responsibility was recognized. Mr. Geesman inquired as to the reference in Mr. Wardell's written fact finding report [all fact finding reports were made available in draft form on the Committee's internet website prior to the meeting] to GQD panel alarm relay modules being obsolete with no spares in stock and that . DCPP will need to procure 15 replacement modules through end of plant life. Mr. Geesman inquired whether the reference to plant life referred to five years or to twenty years. Dr. Budnitz reported the DCISC would follow up on Mr. Geesman's inquiry with the EDG system engineer.

On a motion by Dr. Peterson, seconded by Dr. Budnitz, the January 24-25, 2024 Fact Finding Report, together with Resolution 2024-03, was unanimously approved.

A short break followed.

XIV DISCUSSION, DIRECTION AND ACTION, AS APPROPRIATE, BY THE COMMITTEE, CONSULTANTS & COUNSEL

The Chair requested Assistant Legal Counsel Rathie to make the next report.

C. Status of Governmental Agency Interactions, Responses to SB846 Directives, Administrative, Regulatory, Contractual (Ratify Amendment No. 1 and Consider Approval of Amendment No. 2 to Agreement for Consultant Services with Dr. Mark T. Kirk), Financial and Future Funding Matters, and Other Committee Discussions.

Regarding interaction with government agencies Mr. Rathie began by paying tribute to Ms. Rochelle Becker, Executive Director of the Alliance for Nuclear Responsibility, who made a remark some time ago about the number of committees that are involved with Diablo Canyon issues and that these committees ought to be talking to one another. Mr. Rathie remarked he found this to be an important insight. He reported he recently participated in Dr. Lam's meeting with California Energy Commission Chair Mr. David Hochschild, Vice-Chair Mr. Siva Gunda, Executive Director Drew Bohan, Senior Nuclear Policy Advisor and Emergency Response Coordinator Dr. Justin Cochran and Senior Policy Advisor Mr. Ken Rider. Mr. Rathie reported Committee representatives have met remotely on several occasions with representatives of the DWR to coordinate reviews required by SB846 including the updated seismic assessment required as a condition of the loan agreement for the continued operation of DCPP. Mr. Rathie recognized the presence in the audience of Mr. Jerry Bischof who is serving as a consultant to the DWR. He reported Committee representatives have met and discussed various matters including the open rulemaking matter [R.23-01-007] pending before the CPUC with the Commission's Energy Division staff and concerning the CPUC Decision on Phase 1 Track 2 of that proceeding in which the Commission conditional approved the extended operation of DCPP for up to five additional years [after termination of the current operating licenses].

Mr. Rathie reported the members of the Committee remotely attended a meeting of the CPUC Independent Peer Review Panel (IPRP) for the review of seismic issues related to DCPP held on November 9, 2023 and another meeting of the IPRP is now scheduled in April or May 2024. In concluding this portion of his report Mr. Rathie reported that with Consultant McWhorter he listened by telephone to the NRC's public meeting on the scope of the environmental review for the License Renewal Application.

Mr. Rathie reported in its response to SB846 the Committee has completed its review of any seismic upgrades required in connection with continued operation and continues to plan for its review of the PG&E Updated Seismic Assessment required by SB846 on which Dr. Budnitz will provide more details and the Committee has completed its comprehensive review of "deferred maintenance" and has continued to review maintenance issues in context of SB846. He reported the Committee's 33rd Annual Report has been distributed in accordance with the direction in SB846 and it is available on the Committee's website at www.dcisc.org. In September 2023 he reported the DCISC engaged the services of Dr. Mark Kirk to conduct a study of the integrity of the Unit 1 reactor pressure vessel and Dr. Kirk's two reports have been available on the Committee website since February 1 and Dr. Kirk will be making a report this public meeting.

Concerning administrative matters Mr. Rathie remarked that now that Dr. Lam has announced he would be stepping down from his position on the DCISC at the conclusion of his term on June 30, 2024, the CEC will have a difficult task to identify a qualified candidate who can replace Dr. Lam and Mr. Rathie observed Dr. Lam has given wonderful service to the Committee and will be greatly missed. Mr. Rathie reported that Governor Newsom recently reappointed Dr. Peterson to another three-year term on the DCISC beginning July 1, 2023 and continuing through June 30, 2026 to continue to his service to the citizens of California. Mr. Rathie reported he has had conversations with Consultants Wardell and McWhorter concerning revising the Committee Policies and it is hoped that certain revisions may be brought forward at the June 2024 public meeting. Mr. Rathie reported that on October 25, 2023, approval was received from the CPUC for a Third Restatement of the Charter for the Committee which revisions from the second Restatement addressed only those changes made by CPUC Decision 23-08-004 in Phase 1 Track 1 of R.23-01-007 approving changes in funding for the Committee during the period of transition and relicensing, that is to the end of 2025 when Mr. Rathie speculated that funding for the Committee's operations will again change during the period of extended operation.

Mr. Rathie then introduced and asked special counsel for regulatory matters Mr. Willis Hon to make the next presentation concerning regulatory matters. Mr. Hon reported rulemaking proceeding R.23-01-007 is split into two tracks, each with two phases. Phase 1 Track 1 dealt with funding for the DCISC and with Mr. Rathie Mr. Hon met remotely concerning amendment of the Committee's Charter with CPUC Energy Division representatives and to discuss the development of cost estimates for DCISC operations during the transition and relicensing period. Since that time, the CPUC proceeded to adopt Decision 23-12-036 conditionally approving extended operation of DCPP for Unit 1 until 2029 and for Unit to until 2030. The conditions include that the NRC continues to authorize operations, the loan agreement by DWR is not terminated, and the Commission does not make a future determination that extended operations are imprudent and unreasonable. Phase 1 Track 2 also addresses some of the cost allocation and ratemaking mechanisms for PG&E during the period of extended operation.

Mr. Hon reported that PG&E and Californians for Renewable Energy (CARE) have each filed an application for a hearing of D.23-12-036 which will be addressed by the CPUC in the coming months and the CPUC has moved on to Phase 2 of R.23-01-007 and has issued a ruling asking for comments on the issues to be considered in Phase 2. One of those issues is likely to be funding for the Committee during extended operation. It is anticipated the CPUC will hold a pre-hearing conference to hear from the parties. The DCISC is not a party to any of these proceedings. A scoping memo will then issue together with a schedule for Phase 2 of the proceeding.

The Committee took up approval of two contract amendments to the Agreement with Dr. Mark Kirk entered into in September 2023, to increase his compensation for the study of Unit 1 reactor pressure vessel integrity. Mr. Rathie reported Amendment No. 1 was executed by the Chair in the interim and was now before the Committee for ratification and Amendment No. 2 was now before the Committee for approval. The effect of these amendments is to increase Dr. Kirk's compensation to an amount not to exceed $61,000. Dr. Lam remarked the agreement with Dr. Kirk is entered into by the full Committee and until the Committee makes its decision on the disposition of Dr. Kirk's report, the report stands on its own concerning the PTS phenomenon.

Ms. Sherry Lewis of Mothers for Peace was recognized. In response to Ms. Lewis' query Dr. Lam responded that Dr. Kirk's report was provided to PG&E for its review of only factual information in the report and PG&E was specifically requested by the Committee not to comment on Dr. Kirk's conclusions.

Dr. Gene Nelson on Californians for Green Nuclear Power was recognized and he commented he briefly reviewed Dr. Kirk's reports and was impressed with its thoroughness and applicability of the reports in addressing questions being raised by the public regarding the safety of Unit 1.

Mr. David Weisman representing the Alliance for Nuclear Responsibility was recognized. Mr. Weisman thanked Mr. Rathie for his comments concerning Ms. Becker and he commented she was instrumental in the founding of this Committee through a CPUC decision in 1988 and she was also instrumental in the creation of what is now the IPRP, having been involved in the creation of a similar committee for the San Onofre Nuclear Generating Station (SONGS) in southern California. Mr. Weisman remarked Ms. Becker has for 35 years advocated and remained involved in issues concerning nuclear power and he thanked the Committee for recognizing her commendable actions over nearly four decades.

Upon a motion made by Dr. Budnitz, seconded by Dr. Peterson, the Committee Members unanimously ratified Amendment No. 1 and approved Amendment No. 2 to the Agreement with Dr. Mark Kirk.

Mr. Rathie reported that the Committee has not had to cancel or curtail any of its planned activities due to funding constraints during the time it has been performing additional review activities in response to SB846. He reported, however, the Committee did exceed in 2023 the amount of funds provided by PG&E's ratepayers under the terms of a CPUC decision. He reported the Committee under decision D.23-08-004 now receives additional funding for its activities from the Diablo Canyon Transition and Relicensing Memorandum Account (DCTRMA) and for 2023 the amount of $213,500 was provided under the DCTRMA. However, this amount was not sufficient to cover all the Committee's expenses in 2023, but going forward into 2024 the shortfall will be made up through an invoice submitted for 2024 under the DCTRMA funding formula. Upon a motion by Dr. Budnitz, seconded by Dr. Peterson, the Committee unanimously provided authority to Mr. Rathie to submit an invoice to PG&E for funding for calendar year 2024 under the DCTRMA. Mr. Rathie reported the Committee will continue in the future to return any funds received from the PG&E ratepayers and remaining unspent at the end of a calendar year to PG&E for credit to its ratepayers and will return any unspent DCTRMA funds during the fourth quarter of 2025 in accordance with D.23-08-004.

D. Discussion of New DCISC Initiatives Related to Extended Operations Under SB846, License Renewal, and Changes of Emphasis in Upcoming Fact-Finding Meetings.

Mr. Rathie reported this item was placed on the agenda to allow the Committee members

to discuss how the Committee's review activities may change due to the role played by the License Amendment Application in determining the areas and issues to be reviewed during fact-finding and public meetings.

Dr. Budnitz remarked the License Renewal Application includes dozens of different technical areas which the NRC staff will be reviewing and submitting requests for additional information to PG&E which the DCISC should also separately review and he observed the DCISC may identify other issues to be reviewed and it is possible a third party may introduce comments with yet more issues for the Committee to review. Consultant McWhorter observed some of the issues which may arise as a result of the License Renewal Application include the requests for information, processing and implementing the Aging Management Plans, resumption of spent fuel movement from the spent fuel pools to the ISFSI, the implementation of projects to support license renewal and staffing and employee retention in support of license renewal. Dr. Budnitz remarked the license for the Orano firm's new spent fuel storage system has yet to be received and the DCISC has committed to complete a technical review of the modified design required for DCPP's high seismic environment.

Dr. Budnitz reported SB846 requires PG&E to support an independent updated seismic assessment and PG&E has assembled a team of experts to conduct that assessment and a different group to conduct a participatory peer review which Dr. Budnitz described as an ongoing peer review which continues throughout the process. Dr. Budnitz remarked he believes the experts engaged by PG&E for both the assessment and the participatory peer review were all first rate, competent and very well-credentialed individuals. The assessment follows what Dr. Budnitz described as the spirit of the Senior Seismic Hazard Committee (SSHAC)[16] Level 1 analysis. Dr. Budnitz reported four technical meetings were conducted and the DCISC was invited to attend each meeting. Dr. Budnitz reported the DCISC representatives did not provide any technical feedback to the team and acted only as observers. He reported draft reports were provided to the Participatory Peer Review Panel and the DCISC for review under confidentiality restrictions. Dr. Budnitz reported he has reviewed the Assessment and will be providing an evaluation concerning the Assessment that is based upon the technical merits and the process used by the reviewers and the CPUC Independent Peer Review Panel (IPRP) is scheduled to meet in April or May 2024. Dr. Budnitz reported that under SB846 the DCISC will also review and incorporate the report of the IPRP. Dr. Budnitz reported he does not expect to be able to present a full report to the Committee at its June 20-21, 2024 public meeting. He remarked the NRC review of the License Renewal Application may also generate questions concerning seismic adequacy which the DCISC would review.

Mr. John Geesman on behalf of the Alliance for Nuclear Responsibility was recognized. Mr. Geesman remarked he believed that in the briefing Dr. Budnitz gave to the Diablo Canyon Decommissioning Engagement Panel shortly after the adoption of SB846 Dr. Budnitz undermined his credibility concerning his substantive analysis as well as the credibility of the Updated Seismic Assessment. Mr. Geesman requested that in his procedural analysis Dr. Budnitz address the justification for PG&E choosing to vary from the requirements of the SSHAC Level 1 process. Mr. Geesman further observed that the PG&E Geosciences Department was previously faulted and found not to be in compliance with its own quality assurance procedures concerning which Dr. Budnitz has assured the public that there was no safety impact. Mr. Geesman commented he assumes Dr. Budnitz will likewise assure the public that what Mr. Geesman described as the violations of the SSHAC Level 1 standards will have no impact on safety. He requested that any such analysis should address why or how variation from the specified SSHAC rules bolsters the credibility of the Updated Seismic Assessment.

Mr. Geesman reported that in 2008 the California Energy Commission made policy recommendations which the DCISC followed, with what Mr. Geesman described as some degree of diligence, to try to lower the density of the spent fuel stored in the spent fuel pools. He commented this was an important safety priority embraced by the Energy Commission, the CPUC and by the DCISC but he commented he has heard no mention of this issue in context of consideration of PG&E's revised plans for spent fuel movement during extended operations. Mr. Geesman commented he believes the objective of reducing spent fuel pool density was a principal factor in the selection of the Orano firm to supply a new spent fuel storage system for DCPP. He stated if the DCISC has abandoned this objective this needs to be clearly addressed, as it continues to be of considerable importance to the Alliance for Nuclear Responsibility and to local residents.

Dr. Lam replied that as the appointee of the California Energy Commission to the DCISC he made numerous inquiries of PG&E concerning the delay in implementing the Energy Commission's priority and he determined that PG&E has done a reasonably adequate job in exploring options for reducing the rack density in the spent fuel pools but he stated DCPP is running out of space to store spent fuel and there are numerous procedural and technical barriers to implementing the objective of decreasing rack density including the need to configure the spent fuel pools to provide adequate shieling and DCPP's use of high burnup fuel. The capacity of the Independent Spent Fuel Storage Installation (ISFSI) is also a factor and Dr. Lam remarked the issue is not being focused upon at the present time due to policy and technical barriers. Mr. Geesman remarked that PG&E has assured the Committee that DCPP has sixty years of capacity with the ISFSI and both spent fuel pools filled, but as Dr. Budnitz has observed, this is not a long-term solution. Mr. Geesman stated the issue of spent fuel density remains important and he observed the Legislature in adopting SB846 would expect the cost of additional dry cask storage, even if it required an expansion of the ISFSI, to be included with the cost effectiveness determinations the CPUC is charged to make.

Dr. Gene Nelson of Californians for Green Nuclear Power was recognized. Dr. Nelson observed that in 2015 the NRC recognized that the plant had adequate margin for any plausible seismic event and the statistics and physics in support of that determination have not changed. Dr. Budnitz replied that since the 2015 seismic review was undertaken there has been a lot of new information received and that information is the central focus of the Updated Seismic Assessment which the DCISC is charged with reviewing.

XV ADJOURN AFTERNOON MEETING

The Chair adjourned the morning session of the DCISC at 4:40 p.m.

XVI RECONVENE FOR EVENING MEETING

Dr. Lam reconvened the evening meeting of the DCISC at 5:15 p.m.

XVII COMMITTEE MEMBER COMMENTS

There were no comments by Committee Members at this time.

XVIII INFORMATION ITEMS BEFORE THE COMMITTEE

Dr. Lam requested Mr. Garcia to introduce the first of the informational presentations requested by the Committee of PG&E for this public meeting. Mr. Garcia introduced DCPP Director of Strategic Initiatives Mr. Philippe Soenen who has made presentations to the Committee in the past in his previous capacity as Licensing Manager for Decommissioning Environmental Activities. Mr. Garcia reported Mr. Soenen holds a Bachelor of Science Degree in Mechanical Engineering from the University of California at San Diego. Mr. Soenen has more than twenty years of experience in the nuclear industry including holding a number of positions at DCPP including Licensing Supervisor, Project Manager for License Renewal and as Licensing Engineer for the original DCPP and Humboldt Bay Nuclear Power Plant ISFSI applications for dry cask storage facilities.

A. Briefing on Section 4.2 of New License Renewal Application Reactor Vessel Neutron Embrittlement Analyses, Including a Briefing on the Recent Attempt to Retrieve Capsule B from Unit 1.

Mr. Soenen reported he would provide information on the contents of the License Renewal Application (LRA) and on the recent attempt to withdraw Surveillance Capsule B[17] from Unit 1. Mr. Soenen reported DCPP's reactor vessel integrity program is in full compliance with the federal oversight regulations. PG&E's LRA includes the basis for PG&E's conclusion that the reactor vessels will remain safe for sixty years of operation using currently available information and current methodologies endorsed by the NRC. The NRC will perform an independent review of this information as part of the LRA and PG&E is planning to withdraw Capsule B during refueling outage 1R25 in the spring of 2025. Capsule B will then be tested and results reported to the NRC.

As background information Mr. Soenen stated that during plant operation over time embrittlement caused by neutron fluence can reduce the fracture toughness of the ferritic steel of the reactor vessel beltline material and can also expand the beltline material. To support forty years of operation (i.e., the duration of DCPP's current operating licenses), as part of the Technical Specifications (TS) and the operating licenses PG&E is required to reduce the potential for negative effects from neutron embrittlement within the control bands of a pressure thermal limit. Pressurized Temperature (PT) limit curves are developed and updated based on changes in the reactor design and on updated fluence information to ensure DCPP continues to operate within the safety zone and also to set safety positions for the Low Temperature Overpressurization Protection (LTOP) System.

Mr. Soenen stated federal regulations require all operating U.S. reactors to have a Reactor Vessel Material Surveillance Program. This includes the periodic withdrawal and testing of surveillance capsules installed in the reactor vessels in locations where they are exposed to greater fluence than the vessel itself in order to provide a forecast and projection of how fluence will be interacting over time with the reactor material. The Reactor Vessel Material Surveillance Program is a requirement for the current plant's forty-year operating license period and has been satisfied for both Units. Mr. Soenen provided a reference to the citation for the safety evaluation by the NRC that the Reactor Vessel Material Surveillance Program requirements have been met.

Mr. Soenen reported to support license renewal reactor vessel neutron embrittlement calculations for sixty years of operation are updated and presented in DCPP's LRA in Section 4.2:

→ LRA Section 4.2.1, Neutron Fluence Projections;

→ LRA Section 4.2.2, Pressurized Thermal Shock;

→ LRA Section 4.2.3, Upper Shelf Energy; and

→ LRA Section 4.2.4, P-T Limits and Low Temperature Overpressure Protection (LTOP).

He stated the NRC will be independently reviewing the LRA to verify DCPP Unit 1 and Unit 2 can safety operate for sixty years.

Mr. Soenen stated that surveillance coupons previously withdrawn from the DCPP reactor vessels as part of the Reactor Vessel Material Surveillance Program have determined that fluence experienced through reactor operation, as confirmed by a calculation performed by the Westinghouse[18] firm [in report WCAP-17299-NP, publicly available as part of DCPP's LRA submittal], demonstrate the fluence values supporting a projection of sixty years of operation. The calculation also determined additional reactor vessel materials should be monitored based upon regulations.

Mr. Soenen reported concerning Unit 2 that all the reactor vessel surveillance coupons have been withdrawn and data provided in the LRA demonstrates acceptability through sixty years of operation. For Unit 1 data is provided in the LRA to demonstrate acceptability through sixty years of operation. Mr. Soenen reported the LRA credits withdrawing one final capsule from Unit 1, known as Capsule B, for testing to support up to sixty years of operations. Dr. Peterson observed this will be an issue of high importance that the DCISC will be discussing and he remarked it is important that Capsule B be successfully withdrawn in the 2025 Unit 1 refueling outage. Dr. Peterson remarked the Committee may want to consider making a recommendation that Capsule B be withdrawn even in the event the refueling outage needs to be extended to do so. Mr. Soenen replied PG&E agrees and has high confidence in being able to withdraw Capsule B during the next Unit 1 refueling outage as the reactor vessel will be in a different configuration due to removal of the reactor core barrel which is required to conduct other inspections. In response to Dr. Lam's inquiry Mr. Soenen replied if DCPP is unable to take credit for Capsule B there are other options for demonstrating fluence projections including by external vessel fluence monitoring and through correlations that the current forecast or projections are conservative and he remarked there are also potential options for modifying how the reactor is operated to stay within limits.

Mr. Soenen confirmed that even without credit for Capsule B the plant could still move forward with the LRA as withdrawal of Capsule B is not a requirement for license renewal, rather under NUREG 1801[19] it is a viable option in context of the Aging Management Program. In response to Dr. Lam's request for an analysis if credit is not taken for Capsule B, Mr. Soenen replied that such an analysis is now contained in the LRA, as the withdrawal of Capsule A and use of other applicable industry information demonstrates DCPP can operate for sixty years. He remarked Capsule B's data would be confirmatory as part of the Aging Management Program. In response to Dr. Lam's query concerning the complexity of the effort to undertake such an analysis Mr. Soenen replied he would need to look into what alternative evaluations would be necessary if DCPP were not able to use the validation of Capsule B data in the LRA and he stated he would follow up with a response to the Committee on this matter. In response to Consultant McWhorter's question Mr. Soenen stated the results of the testing and analysis of Capsule B must by regulations be submitted within eighteen months of the capsule being withdrawn from the vessel, but he stated PG&E is hopeful of completing that process within one year of withdrawal. In response to Dr. Peterson's inquiry Mr. Soenen stated he believes Capsule B would need to be stored due to its radioactive decay heat for approximately sixty days before it could be opened but the shielding in the transportation package is quite advanced and it is not a challenge to transport a capsule off-site. Dr. Peterson observed the capsule is likely stainless steel but the material inside [the surveillance coupon] is ferritic and not subject to activation to the same degree as the capsule.

Mr. Soenen stated the LRA relies on NRC-approved methodologies to project PTS and upper shelf energy (USE) values for sixty years of operation [termed PTS reference temperature and Charpy USE]. NRC regulations provide PTS reference temperature and Charpy USE screening criteria and the LRA provides the results of calculations which are derived or summarized in the LRA from the Westinghouse's calculation provided as part of the LRA [the analysis, WCAP-17315-NP, is publicly available as part of DCPP's LRA submittal - see LRA Tables 4.2.2-1 & 2]. Mr. Soenen reported the results of this analysis demonstrate the beltline materials and extended beltline materials remain below the NRC PTS reference temperature and Charpy USE screening criteria and that it is safe to operate Unit 1 for sixty years.

Mr. Soenen stated pressure thermal limits are updated as required by the Technical Specifications and by the operating licenses for DCPP and are maintained in the Pressure Temperature Limits Report which is submitted to the NRC. The Report is periodically updated as the pressure thermal limits are inputs to supporting safety systems, including the LTOP System, to ensure that if pressure were released prior to a catastrophic condition based on low temperature set points, the safety systems would respond as designed. He reported the LRA commits to the existing Technical Specification requirements for managing the pressure thermal limits throughout the period of extended operation. In response to Consultant McWhorter's inquiry concerning at what point the assumed fluence values in the Pressure Temperature Limit Report (PTLR) for a forty year end-of-life get reanalyzed and resubmitted for sixty years of operation Mr. Soenen responded there is a license amendment request (LAR) being developed now for submission to the NRC during the first half of 2024 to update the PTLR. Mr. Soenen stated the LAR will be implemented sometime before the first half of 2025. Dr. Budnitz inquired concerning the percentage of uncertainty in the estimates of fluence in the PTLR for a forty-year lifecycle and Mr. Soenen responded that the uncertainties were calculated within the limits of the methodology, but he did not know the specific percentage.

Mr. Soenen next described the attempts to withdraw Capsule B from Unit 1 during refueling outage 1R24. He reported PG&E was aware entering into 1R24 there were going to be challenges in removing Capsule B due to application of sufficient force necessary to effect its removal. He reported PG&E submitted a request to the NRC which was approved for revision of the withdrawal schedule to either fall of 2023 or spring of 2025 which he stated was consistent with license renewal guidance documents not to have more than two times forty years of equivalent full power operation. Mr. Soenen reported when Capsule B is removed in 2025 it will have approximately 101 effective full power years (EFPY) of fluence data and this meets the guidance documents not to have more than 108 EFPY of data. He confirmed Dr. Peterson's observation that if Capsule B were to remain in the reactor beyond 1R25 it would exceed the guidance document's limit for fluence.

Mr. Soenen described photos and displayed short videos of the interior of the Unit 1 Reactor Pressure Vessel showing the location and configuration of the area around Capsule B and its access plug as well as the tool that was used to attempt to remove the capsule from the vessel. He observed Capsule B is located on the exterior of the core barrel, closer to the fuel than the reactor vessel. He described a video showing the attempts to retrieve Capsule B with a hand tool which failed to engage the gripping mechanism. He remarked DCPP believes there is a distortion or deformation of a specific area on Capsule B and the difficulties are not being caused by swelling or other material defect. Mr. Soenen reported the same tool was able to engage at two other capsule locations. He reported the last time removal of Capsule B was attempted the tool engaged but the force used was insufficient. However, during 1R24 a different issue was experienced. During 1R24 sizing gauges were used to ensure the tooling is within minimum size for Capsule B and this should lead to a greater chance of success.

Mr. Soenen described and displayed visuals of the configuration of the reactor core barrel and the changes in configuration and greater access that will be afforded by removal of the core barrel during 1R25. He remarked during 1R24 there was a concern that the single tool available could be damaged and thereby potentially introduce foreign material into the reactor core or the tool could get stuck and he reported the same tool is also used, after removal of the plug, to retrieve the surveillance coupon and extract it from the capsule. A tool is specifically designed for each unit and Mr. Soenen reported DCPP will have more tools available at the next outage. In response to Consultant McWhorter's observation Mr. Soenen confirmed the tool used with Unit 2 was stored within Unit 2 Containment and was unavailable during 1R24. He reported in the future DCPP will store these tools outside of Containment. Mr. Soenen confirmed Dr. Peterson's observation that when the core barrel is removed from the reactor Capsule B will come with the core barrel and be available to be worked on outside of the reactor vessel which will afford more options, including better access and side access and less chance of introducing foreign material. Mr. Soenen reported that if necessary with underwater cutting technologies the plug could be cut out.

In concluding his presentation Mr. Soenen reported there is limited operating experience available with the challenges inherent with the removal of a surveillance capsule and plug and DCPP is also identifying other options. He displayed a video from the removal of the core barrel during 2024 and he described some of the components involved.

The Chair observed the agenda calls for public comment following the next presentation by Dr. Mark Kirk and he requested DCISC Consultant Dr. Andrew Kadak to introduce Dr. Kirk.

Dr. Kadak reported Dr. Mark Kirk holds a Ph.D. in Civil Engineering from the University of Illinois, a Master's of Science Degree in Mechanical Engineering from the University of Maryland and a Bachelor of Science Degree in Engineering Science and Mechanics from the Virginia Polytechnic Institute. Dr. Kirk previously worked for Westinghouse and for the NRC and now runs a private consulting company. Dr. Kirk is a member and former Chair of the American Society of Mechanical Engineers Working Group on Operating Plant Criteria for Reactor Vessel Material Studies and Embrittlement and has worked extensively on the development of codes and standards used in regulatory guidance for assessment of reactor vessel embrittlement.

D. Results of Studies by Dr. Mark T. Kirk Evaluating Unit 1 Reactor Pressure Vessel Integrity and Addressing Public Concerns.

Dr. Kirk stated he would be dividing his report into four sections as follows: background, administrative information, measurement and prediction of embrittlement, and the conduct of reactor pressure vessel integrity management and in his report he would discuss current NRC requirements and guidance on these topics.

Dr. Kirk reported the objectives of his efforts as directed by the Committee were to address concerns raised by the Mothers for Peace and the Friends of the Earth organizations as well as by Mr. Bruce Severance. This resulted in a two-part report, both parts of which have been available on the DCISC website www.dcisc.org since February 1, 2024. Part 1 is focused on explaining reactor pressure vessel (RPV) integrity and embrittlement concepts and addressing public concerns and Part 2 explains Dr. Kirk's evaluation of the embrittlement of DCPP Unit 1. The draft Report was reviewed by the Committee's Technical Consultants and individually by each DCISC Member, but there was no discussion between Members concerning the Report. The draft Report was also provided to PG&E strictly for the purpose of checking for omissions or errors of fact. Dr. Kirk stated these reviews did not affect any of the Report's conclusions.

Dr. Kirk stated the overarching concern of the public is whether the continued operation of Unit 1 is safe and what does data credibility mean when discussed by the NRC and nuclear engineers and how does it affect the analysis. There is also concern about surveillance capsule withdrawal plans and the use of sister plant data obtained from the Palisades Nuclear Plant in Michigan ("Palisades" or sometimes "sister plant").

Relative to background information Dr. Kirk reported embrittlement is the phenomenon that reduces steel's resistance to fracture and it changes the steel RPV at a micro structural level. Dr. Kirk stated it is important to understand that embrittlement does not cause cracking at a macro level such that the cracking can be detected by a routine ten-year in-service ultrasonic inspection. He reported there has been discussion of a postulated linkage between the quantification of the level of embrittlement and the need to do more frequent inspections and he commented there is no linkage between the two. Embrittlement reduces the energy absorbed by steel before it fractures and is measured and surveilled using the Charpy[20] specimen test and he displayed a photo of a Charpy specimen and reported specimens are tested across a range of temperatures by being broken into two pieces while measuring the energy it takes to do so. At low temperatures the amount of energy absorbed is very low and at high temperatures the reverse is true and there is a lot of bending of the material before breaking. The temperatures in between are termed transition temperatures. Dr. Kirk stated over time with embrittlement occurring the steel's microstructure is changed by the neutron radiation from a nuclear reactor and the amount of fracture energy from the lower shelf to the upper shelf reduces and this is characterized by the Charpy tests as the reduction or change in Upper Shelf Energy (USE) or as a percentage drop in USE and by an increase above the transition temperature which is measured by convention at 41 joules[21] or 30-foot pounds of absorbed energy, referred to as Δ T_41j.[22]

Dr. Kirk observed embrittlement occurs progressively over the life of a nuclear power plant. It occurs relatively quickly early in a plant's lifetime and slower as the plant ages. Dr. Kirk reported it is a misunderstanding that there is a linear relationship between embrittlement and the passage of time. In context of a license renewal for operations from 40 to 60 or to 80 years of service the phenomenon saturates and the amount of embrittlement is much less, with the form of the curve controlled by the composition of the steel and the temperature of the exposure which are accounted for in predictive equations and reflected by surveillance.

Dr. Kirk stated fracture toughness data is required in order to assess a plant's structural integrity and to ensure sufficient material resistance to breaking under load. However, the Charpy specimen test does not directly measure fracture toughness. The notch on the Charpy specimen is how and where fracture toughness is defined as the resistance of the material's fracture in the presence of a very sharp crack such as would be produced from fatigue or stress corrosion cracking. Fracture toughness data is recommended by the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (BPV) Code, but only Charpy data can be measured because the specimens are located within the capsules. However, Dr. Kirk reported there is a good correlation between the Charpy T_41jdata and fracture toughness and this is used by all nuclear plants to infer fracture toughness.

Concerning the Surveillance Program Dr. Kirk reported surveillance capsules are loaded with both Charpy and fracture toughness specimens and also with dosimeters used to measure the neutron fluence occurring over time. The capsules are loaded into the reactor core as part of the reactor vessel's original construction and he displayed a cross-section of a RPV showing the location of capsules arranged around the reactor core barrel and around the core baffles that hold the fuel assemblies in place. For both DCPP reactors all the capsules are attached to the core barrel or to the vessel wall and all have a lead factor, that is, they are closer to the nuclear fuel than the RPV itself such that they accumulate neutron dosage faster than the RPV which Dr. Kirk described as an important aspect of the Surveillance Program as this allows a forecast based on the lead factor as determined by ASME guidance. He gave as an example a capsule with a lead factor of three having been kept within the core for fifteen years which would then have accumulated a dose representing the amount of neutron accumulation on the vessel after forty-five years of operation. Dr. Kirk observed this lead factor provides sufficient time for regulatory oversight and planning. The specimens in the capsules experience more embrittlement than does the RPV and their condition represents that of the RPV many years into the future. Dr. Kirk observed this is why long intervals between capsule withdrawal are acceptable. In DCPP's case, for Unit 1 Capsule V, the third capsule withdrawn, was removed from the RPV in 2002 and at that time had the same fluence that the Unit 1 RPV will experience this year or next year. He reported the long delay in removal of capsules is part of the surveillance process.

Dr. Kirk stated with the direct measurement of the state of neutron exposure or fluence, this data is used to assess the condition of the reactor in conjunction with a predictive model to forecast future RPV embrittlement and he reported the NRC provides guidance on when plant-specific data or a formula is to be used. He reported this generates the discussion of credibility of data. Dr. Kirk reported a determination is not made based upon a finite number of samples, but is supplemented by a model which has been calibrated to represent embrittlement trends in a fleet of nuclear reactors. He commented until the first capsule is removed all one has is the formula to use to extrapolate current conditions.

Concerning the assessment of RPV integrity Dr. Kirk reported the main point to be understood is the process is designed to ensure that the resistance of the material to fracture always exceeds the structural driving force. The NRC has set up screening criteria on pressure-temperature operating limits, PTS as a value of transition temperature (expressed as RT_PTS) which criteria must remain below 130° Celsius and screening criteria on USE which must exceed 68 joules. Dr. Kirk explained the screening criteria are not failure conditions, but represent the conservative establishment of a very low probability. When a plant is expected to exceed these screening criteria at some future time the plant must take some additional action and create and implement a plan and submit the plan to the NRC at least three years in advance to ensure time for review and questions. The plan could include cessation of operation, a more detailed plant-specific analysis to determine acceptability of exceeding the NRC screening criteria, or could employ specific modifications to plant operation. Dr. Kirk remarked that heating of the water used by the Emergency Core Cooling System (ECCS) has not to his knowledge been used by any plant in the United States.

Concerning the NRC's requirements and guidance for embrittlement monitoring and prediction of RPV integrity, Dr. Kirk reported the NRC's rules, set forth at 10 CFR Part 50 Appendix H, set forth the requirements for surveillance during a plant's initial forty-year license period and incorporate AMSE Standard E-185 by reference. He reported a plant is licensed in accordance with the version of ASME E-185 in effect at the time of its construction and DCPP Unit 1 was licensed under the ASME E-185 Standard in effect in 1970 which requires testing of three capsules during the first forty years of operation. Dr. Kirk reported the NRC provided recommendations in NUREG 1801 for extended operation beyond forty years and based upon the level of embrittlement during its initial license it is possible that these recommendations may be for three, four or five capsules or additional capsules may be required depending upon the level of embrittlement.

Dr. Kirk observed for embrittlement prediction purposes NRC Regulatory Guide (RG) 1.99, Revision 2, published in 1986 provides the NRC's embrittlement prediction model which codifies the original PTS Rule including prediction of both Δ T_41jand the percentage drop of USE. He reported there is an alternate PTS Rule, 10 CFR Part 50 61a, which requires the use of a somewhat different model. It is this guidance and the requirements for which data are to be used in the predictions that are the credibility criteria, meaning that credible data follows the predicted trends from the Regulatory Guide while non-credible data deviates from those trends. Dr. Kirk described how data is plotted on a graph with the Y-axis showing Charpy Shift and the X-axis the Fluence, with each dot on the graph representing a different capsule as being within or outside of prediction lines based on the Regulatory Guide which is based upon copper and nickel content and whether the material is a plate or a weld. A predictive line is drawn, along with a plus or minus one standard deviation confidence band and Dr. Kirk reported it is expected that 68% of the data will fall within those bounds and 32% of the data will fall outside. If more than 32% of the data fall outside the plus or minus bounds then the data is termed not credible. In that case, Dr. Kirk reported more data is collected and permitted to be outside the bounds and still be credible. Dr. Kirk reported credibility is assessed on the entire data set and a credibility assessment is redone with the addition of each data set.

Dr. Kirk reported credibility reveals whether or not a plant's specific data follows the anticipated trend and credible data are used to adjust the Δ T_41j and the USE prediction. Non credible data are modeled more conservatively using the Regulatory Guide formulas. He commented there has been concern that it was wrong that PG&E determined its three capsule data, which was valid from 2002 to 2011, was subsequently found not to be credible and Dr. Kirk remarked there is absolutely no incentive for a utility to call data that is credible not credible as doing so would incur a penalty from the NRC. For PTS, plant specific data is used together with similar data from sister plants. He reported Pressure-Temperature (PT) limits follow the same practice by convention, but it is not a requirement. For USE assessment 10 CFR Part 50 Appendix G makes no reference to sister plant data and Dr. Kirk stated the common practice is not to use sister plant data for USE. He commented RPV integrity screening criteria specify a very high level of material resistance, based on two mechanical properties. Those properties being USE and transition temperature shift for two events, one being normal operation, PT limits during routine heat up and cool down and the other being PTS which he remarked was a postulated accident condition that has never happened, but if it did would be very bad.

Concerning the evaluation of DCPP Unit 1 Dr. Kirk reported he would discuss the Surveillance Program and its status, the Capsule B deferrals, and his evaluation based upon the NRC's requirements and how that compares to PG&E's evaluation. He commented he would also discuss a supplemental evaluation using newer techniques and more data than currently required by the NRC.

The Unit 1 Surveillance Program is licensed to American Society for Testing Materials (ASTM) E-185-70 standard which means three surveillance capsules were required to be tested over the first forty years of Unit 1's operation. Dr. Kirk reported this requirement was fulfilled in 2002. He noted the NRC has stated on several occasions that as Unit 1 was licensed under ASTM E -185-70 the deferrals of the withdrawal of Capsule B were appropriate during this period. He reported that there were plans during the first forty years of Unit 1's operation to test Capsule B, but PG&E was allowed to adjust those plans as withdrawal was not required. Dr. Kirk stated the Comments Mr. Bruce Severance provided to the DCISC mention a letter from the NRC in 2006 which Mr. Severance claims made withdrawal of Capsule B a condition of recovery of the low power operating time which extended the license from September 2021 to November 2024. Dr. Kirk reported that although he cannot provide a legal interpretation of Mr. Severance's claim, in his twenty years with the NRC it has been his experience that if the NRC were to impose a license condition it would be stated in the cover letter and he does not believe the reference cited by Mr. Severance constitutes a license condition.

Dr. Kirk stated that as Unit 1 goes from forty to sixty years of operation, NUREG 1801 provides the NRC's recommendations which include that two more capsules be tested based upon the anticipated level of embrittlement. He reported Capsule B is planned for withdrawal in 2025 and subsequent testing and Dr. Kirk observed NRC guidance provides for its removal by 2028. Dr. Kirk commented PG&E's plan to test one capsule rather than two will likely be a subject of discussion with the NRC. He reported the Palisades sister plant data which is part of the requirements for PTS assessment was incorporated in 2011 and this provides data through and beyond sixty years of service. He commented that since 2011 the PT limits, the PTS assessment, and the USE assessment have all been informed based on data for beyond sixty years of service.

Dr. Kirk then displayed a series of PowerPoint slides showing how knowledge has evolved over time of the embrittlement level for PTS for Unit 1. From 1985, when the plant began operations to 1987 when the first capsule, Capsule S, was tested the data from this capsule was not credible. From 1993 to 2003, the curve was adjusted downward to follow the data, and the predicted crossing point for the reference temperature estimate for RT_PTSfrom the testing of an additional capsule was beyond sixty years. From 2003 to 2011 with the testing of Capsule V the data was deemed not credible due to the predicted crossing point with the Capsule V data and due to the scatter in the data with the unirradiated capsule from the commencement of operation. This was the situation between withdrawal of Capsule V and the recognition that sister plant data was available from Palisades. With two new data points from Palisades the data was again credible and the RT_PTSvalues at forty and sixty years are well below the NRC's PTS screening criteria of 132° Celsius. Dr. Kirk stated this represents the present situation until more data, including from Capsule B, becomes available when the entire process will be redone.

Dr. Kirk reported embrittlement, especially for copper bearing material such as contained in the Unit 1 limiting weld, is highly nonlinear as in the first twenty years the reference temperature (RT_PTS) increased by a full 100° Celsius, but from year forty to year sixty the RT_PTS

will increase by only 15° Celsius. Dr. Kirk reported this is well understood in all modern embrittlement models. He remarked as credibility is assessed using all available data, when Capsule B is withdrawn and tested nothing may change but if the data is extremely low or high the RT_PTS assessment could change significantly. Dr. Kirk observed the use of RT_PTSdata from Palisades not just at forty years but also at sixty years represents interpolations. He reported there are no extrapolations being done and this methodology does not go beyond the level of knowledge for materials of this type.[23] He reported that his calculations validated PG&E's calculations to within a degree Celsius and he did not find any issues with PG&E's calculations nor with the NRC's review.

With reference to USE Dr. Kirk reported the NRC requires their model, the RG 1.99 model, be adjusted to bound all the available data. For DCPP Unit 1 the model's curve based very near the Capsule Y result, with a difference of only a few foot-pounds which Dr. Kirk observed was not significant. He reported the NRC does not have a position on the use of sister plant data for USE assessments but typically sister plant data is not used. He displayed a graph with the USE projection for Unit 1 which shows at both forty and sixty years both USE projections are well above the NRC's 68 joules screening criterion. He reported his calculations validate PG&E's calculations for USE from 2011. He reported PG&E made a small error on the credibility assessment for USE which the NRC also identified and this small error which was in a conservative direction was corrected.

Dr. Kirk reported the DCISC directed that he employ his personal approach to provide supplemental analysis unconstrained by NRC requirements. Dr. Kirk reported he used more data and more recent analytical techniques which have been discussed, but not yet codified by ASTM or the NRC. He reported he used machine learning inspired technique to identify data from an international database of more than 2,000 surveillance datapoints compiled by ASME and used this database to identify materials with similar embrittlement characteristics and variables based on the copper and nickel content similar to DCPP Unit 1. He reported the intent was similar to the NRC use of sister plant data for PTS. Dr. Kirk reported DCPP Unit 1 has a rather unique combination of copper and nickel and along with Palisades there were only two other pressurized water reactors that previously operated in Germany that provided useful data.

He reported the ASTM embrittlement curve, fit from the larger database, represents the data a bit better than the NRC curve but he reported at this time the plant is required to use the NRC equation which he stated is high relative to the data which in this particular case adds a level of implicit conservatism for the material. The more modern analytical technique is Draft Code Case N-914 in the ASME Code (N-914) and provides instruction on how to use fracture mechanics to determine the presence of adequate fracture toughness. Dr. Kirk reported N-914 is focused on accounting for the effects of embrittlement on fracture toughness properties and permits the use of fracture toughness data along with Charpy data. He remarked that in the past the NRC would only allow use of Charpy data. He commented N-914 provides a methodology that incorporates direct fracture toughness data available for weld testing done at Palisades in both an irradiated and an unirradiated condition. For USE the additional data is identified by the nearest neighbor process but with the RG 1.99 analysis because there has not been as much focus on new embrittlement trend curves for USE.

Dr. Kirk reported regarding the supplemental analysis for PTS the graph now has two added points which trend well after adjustment for differences between fracture toughness and Charpy, with the fracture toughness data helping to remove some of the unneeded conservatism from the traditional Charpy approach. With the curve falling such that the crossing point between RT_PTSand the NRC's PTS screening criteria is off the graph, thus providing further evidence that it is extremely unlikely that Unit 1 will have an issue with PTS screening criteria during a sixty year service life.

Concerning the supplemental analysis for USE, Dr. Kirk stated he considered additional data from the nearest neighbor process, but instead he used the NRC's assessment methodology. He reported the consideration of the similar USE data suggest that Unit 1 may fall below the NRC's 68 joules screening criteria before sixty years, probably in 2029 or 2030. He commented this could be addressed by performing an equivalent margin analysis per RG 1.161. Dr. Kirk stated while he did not perform that analysis he is highly confident that it would show the plant is adequate for sixty years and beyond. He stated that every plant that has done an equivalent margins analysis, removing the unnecessary conservatism in the material properties assumption and the driving force assumption, has without exception been shown to be acceptable relative to the lower USE values.

Dr. Kirk commented with reference to public concern that there were questions regarding the use of sister plant data and whether the accumulation of damage is dependent upon the temperature history of the component and thereby on the power level history and that the complex nature of radiation embrittlement is idiosyncratic to individual reactors and may change unexpectedly over time. Dr. Kirk observed sister plant data provides similar data and allows working with additional data and more data creates increased confidence. Sister plant data is required for PTS but there is no guidance for its application to USE. He stated absolute temperature affects embrittlement and must be accounted for, however, for most of a plant's lifetime the reactor is at 100% power and a reactor is at a higher temperature at a lower power, but the 100% power temperature is conservatively used in these calculations. He remarked it is important to distinguish between science and engineering and the analysis he described looks at the effect through the scatter and through the uncertainty of the Charpy data. Scatter is accounted for conservatively by not basing predictions and lifetime assessments on the mean curve, but rather on the upper bound curve. Dr. Kirk stated it is his belief that the magnitude of the effect on the resultant Charpy shift values is small. He reported data for existing trend curves has been gathered from pressurized water reactors in the U.S., Japan, South Korea, France, Germany and from Belgium and if the idiosyncratic effect of temperature and power level was large, data from France and the United States could not be plotted on the same curve with the same trends identified.

Dr. Kirk remarked concerns have been expressed about the RPV beltline inspections and that the small number of indications found by ultrasonic inspection of Unit 1 were not plausible because twelve years ago many more flaws were found in Belgian reactor pressure vessels. Dr. Kirk reported the flaws in the Belgian reactors were tied to a manufacturing idiosyncrasy that was particular to those reactors and no plausible connection exists between those flaws and Diablo Canyon. He remarked the models cited in the comments, termed Favor and Grizzley, are known to be ultra-conservative and are not intended to represent the flaws that actually occur in vessels and they are not intended to be a conservative representation of flaws for regulatory use. He reported the density of indications found in Unit 1 are similar to those found through industry experience elsewhere.

Concerning a comment that the ultrasonic inspection interval permitted is too long, particularly as Unit 1 is significantly embrittled, Dr. Kirk observed that embrittlement does not cause cracking and embrittlement cannot be detected by ultrasonic examination as it occurs at a much smaller level. He reported surveillance is important, but if surveillance is showing high embrittlement this does not change the inspection frequency. The Unit 1 inspection interval of ten years is required by the AMSE.

Dr. Kirk observed there was a comment made that material damage by hydrogen embrittlement was not considered and he confirmed the comment was accurate as there is no operating experience showing hydrogen embrittlement cracking in light water reactors such as operated at DCPP. He commented the stainless steel liner protects the RPV steel from hydrogen effect cracking and cracking of the liner itself, which is more susceptible to hydrogen cracking than ferritic steel, is prevented by control of cooling water chemistry by keeping the oxygen content of the water very low such that the conditions that enable stress corrosion cracking are not present.

Dr. Kirk reported there has been a proposal to use the nanoindentation testing methods developed by Dr. Peter Hosemann to further investigate the embrittlement status of Unit 1 weld samples. Dr. Kirk reported that hardness can be related to fracture toughness and hardness can be measured, but it is data on fracture toughness that is required and the theoretical models to make that determination between hardness and fracture toughness are not validated and therefore an empirical relation would need to be used to determine hardness, then strength, and then strength to facture toughness. He commented there is a benefit in that a great number of hardness measures can be made, but the correlation process introduces uncertainties in the final predicted value and from a regulatory viewpoint Dr. Kirk believes this would preclude the use of the results. He remarked there is no precedent for using the nanoindentation approach with the NRC and it would complicate any interpretation. Dr. Kirk stated he would recommend the direct fracture toughness approach, using tiny fracture toughness specimens machined from the broken halves of Charpy specimens that have already been tested and for which there is regulatory precedent and he opined this approach rather than sampling hardness would lead to a more certain outcome with the regulator.

Dr. Kirk remarked Dr. Digby Macdonald was concerned the existing Charpy methodology is not sufficiently accurate and Dr. Macdonald has proposed a new Charpy embrittlement metric which Dr. Macdonald terms "Extent of Embrittlement." Dr. Kirk reported his evaluation showed Dr. Macdonald's metric is not a measure of fracture toughness and Dr. Kirk compiled data on both fracture toughness temperature and Charpy transition temperature from a wide variety of RPV steel for a variety of fluences and copper and nickel content and found the Extent of Embrittlement metric predicts fracture toughness transition temperature less accurately that does the T_41j metric because at a fixed extent of embrittlement there is a greater uncertainty in the prediction of fracture toughness transition temperature than with Charpy metrics.

Dr. Kirk reported regarding a comment which questioned why account was not taken for the stainless steel liner in determining susceptibility of the RPV to brittle fracture and hence a LOCA. He commented the NRC has accounted conservatively for defects that could possibly exist in the liner by the defect population that was assumed in establishing the PTS screening criteria and by doing so the NRC assumed larger and more flaws than actually exist in the liner in setting the RT_PTSscreening criteria. He stated the high toughness provided by the thin layer of stainless steel cladding is completely ignored in the structural integrity calculation and therefore the liner is accounted for in a very conservative manner, over-estimating its contribution to cracking and underestimating by eliminating its structural contribution.

Regarding a comment concerning why no attention has been given to low temperature thermal annealing of radiation damage Dr. Kirk replied the surveillance samples are exposed not only to fluence, but also to temperature and the temperature affects are inherently quantified. So whatever self-annealing has occurred at whatever temperature, that is reflected by the samples and therefore in the data used for surveillance.

Dr. Kirk reported on a question raised regarding about how the vessel nozzles were assessed, that is, in the area above the RPV beltline where water enters the core. Dr. Kirk reviewed PG&E's documentation and he stated he is certain PG&E demonstrated that the nozzle materials do not restrict plant operability any more than the beltline weld which is the basis for PT limits and PTS assessment.

Finally Dr. Kirk reported a concern has been expressed that Unit 1 was constructed with deficient materials and known metallurgical flaws due to excessive copper and nickel impurities in the welds and plate material and there were well documented engineering errors made in the metallurgical specifications for Unit 1. Dr. Kirk provide a graph showing the copper content of the entire operating fleet of reactors in the United States and in France plotted by their construction dates. The graph showed that at the time of Unit 1's construction weld and plate materials contained copper and this was typical of pre-1973 chemistries. He reported at the time of Unit 1's construction it was not widely recognized that copper was a factor for causing embrittlement and hence at the time Unit 1 was constructed copper was not restricted. After 1973 the use of copper significantly declined. Dr. Kirk reported a number of plants with greater copper content than Unit 1 have operated safety for many years and 25 reactor vessels with more copper than Unit 1 remain in service today.

In summarizing his presentation Dr. Kirk stated he confirmed and validated PG&E's current reactor vessel integrity calculations and that Unit 1 meets the NRC's requirements for reactor vessel integrity through sixty years of service. He reported PG&E has correctly assessed the credibility of the data and its use of sister plant data was consistent with NRC guidance. He stated deferral of testing of Capsule B was appropriate during the first forty years of service and the vessel inspection schedule was appropriate. Capsule B is recommended to be removed by 2028 consistent with NRC guidance and removal is planned during 2025. Once the data from Capsule B is available this will change the numbers for PTS, for USE, and for the PT limits but the extent of those changes cannot be known until the Capsule B data is available. The supplemental analysis Dr. Kirk performed using additional data and more modern analytical techniques for PTS showed Unit 1 is very unlikely to exceed the NRC's screening criteria in sixty years of operation or beyond. For USE, the NRC's upper shelf energy limit screening criteria may be exceeded in five or six years but Dr. Kirk remarked he is confident that using a more accurate USE analysis, following NRC guidance and using fracture mechanics data, would show acceptable margins well past those dates, but one would first need to do the calculations to be certain.

The Chair requested comments from the other Members and the Technical Consultants on Dr. Kirk's report.

In response to Dr. Peterson's comment Dr. Kirk confirmed test data from Capsule B would be useful to resolve the question around USE as testing the specimens provides both USE and transition temperature data.

Dr. Budnitz commented that he has reviewed Dr. Kirk's report as well as the Comments from Mr. Severance and the Declaration from Dr. Macdonald and he has not identified any arguments to challenge his conclusion that Dr. Kirk's evaluations and conclusions are correct and appropriate and in his view the Committee should not only accept Dr. Kirk's report but also endorse its conclusions but Dr. Budnitz commented he was not ready to make such a motion until he has the opportunity to hear from the public and he reported there is a pending assessment by Dr. Macdonald. He stated he is also open to hearing from Mr. Severance and from any other interested persons.

Dr. Lam reported the Committee has been informed that Dr. Macdonald is ill and his comments on Dr. Kirk's report will be forthcoming in the future. In response to Dr. Lam's request Dr. Kirk confirmed Dr. Lam's impression that Unit 1 meets all NRC regulations without having tested Capsule B. Dr. Budnitz remarked that the NRC criteria appropriately include a good deal of conservatism and even if Unit 1 were approaching the NRC criteria he would not be convinced that the reactor vessel would be in unacceptable condition. Dr. Kirk remarked that based on the screening criteria and the currently available data Unit 1 is not even close to not meeting the NRC's criteria. Dr. Lam observed Dr. Kirk's statement was based on two margins, that is, both the built-in margin of the NRC regulations and based on currently available data. Dr. Budnitz remarked that if DCPP were closer to not meeting the NRC's criteria for continued operation there are actions the plant could take.

Consultant McWhorter observed that Dr. Kirk included in his report supplementary analysis techniques that are not based on NRC regulations and using those techniques has demonstrated Unit 1 is safe.

Dr. Kadak thanked and commended Dr. Kirk for what he described as an incredible effort and for addressing a very technical topic into a format most people could understand. Dr. Kadak stated the detail of Dr. Kirk's analysis plus the supplemental work undertaken by Dr, Kirk demonstrate that the NRC's regulations are met. Dr. Kadak stated he was curious why the PTS criteria are so well met, but the USE criteria are not, based on the Palisades data in the master curve, and Dr. Kadak remarked he would like to better understand the science of why USE data, using sister plant data or other plant data, does not follow the trend of the PTS data. Dr. Kirk replied that one would need more time and access to the original data records to resolve this question. Dr. Kadak commented that when he served as President and Chief Executive Officer for the Yankee Atomic Electric Company, the Yankee Rowe Nuclear Power Plant in Rowe, Massachusetts had an issue concerning USE and he stated that despite the fact the plant was below the screening criteria it was able to do the fracture mechanics analysis which demonstrated sufficient margin for USE. Dr. Kirk commented the analysis performed for Yankee Rowe was groundbreaking and that analysis is now quite common. Dr. Kirk remarked that every plant that has done a USE analysis has demonstrated USE is far below the 68 joule value which Dr. Kirk commented was a statement of its embedded conservatism.

Mr. Wardell stated he found Dr. Kirk's report to be very impressive and he took from the report that the Unit 1 reactor pressure vessel is in a good condition for operation for up to sixty years according to NRC requirements. However, Dr. Kirk's report goes further with its supplemental analysis and Mr. Wardell inquired what might be required to do the additional analysis of USE. Dr. Kirk responded this would entail a fracture mechanics analysis such as is done for PTS limits, that is, by estimating a flaw that is too large and assuming you have loads that are too high and using fracture toughness properties obtained in principle through direct measurement of plant material and testing the data on the USE to get a J-R curve,[24] but it is a matter of obtaining the data needed for the loading. He confirmed Mr. Wardell's observation that if that analysis were done it would determine the USE. Dr. Kirk commented he would be shocked if the results did not confirm operability for sixty years as it would be the first time for that analysis and there is much uncredited margin in the current requirement.

Mr. Wardell commented it is important to retrieve Capsule B and to receive and review the results of the testing of Capsule B. Dr. Kirk reported at the present time the data includes all the existing capsules which have been removed from the vessel as well as the Palisades data and he commented the Capsule B data although it cannot be predicted with certainty is likely, probably with a degree of confidence of around 95%, to be another data point on the line on the graph in his report. In response to Consultant Wardell's question as to the options available if Capsule B cannot be removed, Dr. Kirk reported one could reconstitute previously tested surveillance coupons as small Charpy specimens which would provide data, but this would not collect data at a higher fluence. He reported capsules could be reinserted and Capsule A, which is currently also in the reactor, could be tested. Dr. Kirk remarked accordingly there are a number of options remaining if Capsule B cannot be removed. Dr. Kadak remarked Capsule A could be removed and tested which would provide sufficient datapoints. Dr. Kirk, in response to Mr. Wardell's question, reported there are no longer capsules in the Palisades reactor vessel and the capsules with the data from Palisades are supplemental capsules which have the DCPP sister weld components which were placed in Palisades in the 1990s and withdrawn a few cycles later because they were in an accelerated position. Other Palisades capsules do not contain the DCPP sister weld. Dr. Kirk remarked making small CTs from existing specimens is straightforward as the location of those specimens is known, Capsule A is still in Unit 1 and current location of the Palisades supplementary capsules is known. Mr. Wardell stated he concludes from the discussion that the NRC analysis provides sixty or more years of operation which would accommodate a twenty year license renewal, and while the USE supplemental analysis does not have the margin sought, there are options to reanalyze USE.

In response to Consultant McWhorter's inquiry as to the options if the Capsule B data results show a huge amount of data scatter, in that event Dr. Kadak replied the next step would be to try to understand why and if considered as not credible to go back to the existing non credible dataset. Dr. Kirk observed a significant problem would be encountered if the value is much greater than expected. Dr. Budnitz remarked and Dr. Kirk concurred that one neither includes nor discards data but accounts for it through a probabilistic analysis as to whether this results in a low or high confidence in the dataset. Dr. Kirk observed that whatever data is produced by Capsule B, the data will represent one hundred years' of neutron exposure and at this point in time there is no contemplation that the license extension for DCPP Unit 1 would ever approach that.

At the Chair's request, relative to time limits for public comment, Assistant Legal Counsel Rathie suggested and the Committee agreed that Mr. Severance be given the ten minutes he previously requested for his comments and the other speakers be allowed four minutes each.

XX PUBLIC COMMENTS AND COMMUNICATIONS ON ITEMS XVIII A.1 AND XIX D

Dr. Lam requested that members of the public who wish to address the Committee on the topics presented this evening do so now.

Dr. Gene Nelson was recognized and he remarked the NRC has evaluated certain second license renewals, that is, for plants planning to run from sixty to eighty years and he stated these plants, all of which had a higher neutron fluence than DCPP for their first relicensing, have been determined to have a through wall crack frequency of less than one in a million per year. He commented no reactor pressure vessel anywhere in the world has experienced a through wall crack and he observed from having seen the graph in Dr. Kirk's report that there is a significant population of operating reactors with a higher copper content than DCPP and 25 of those reactors are operating today. He remarked the screening criteria is very conservative and while more data could be obtained the NRC guidance for second license renewals support continued operation of DCPP.

Mr. William Doe was recognized and stated he is a part-time consultant for PG&E. Mr. Doe reported and Dr. Kirk agreed that if the surveillance capsule data turns out to be a non credible, if the results are more limiting then the standard in RG 1.99 requires that the data be used even though it is not credible and Mr. Doe stated this introduces even more conservatism. He observed that if Capsule B data proves to be an outlier from the six sets of data there will still be six data sets, including Palisades, and one set is allowed to be excluded with the data set still remaining credible. Dr. Kirk stated Mr. Doe was correct and he thanked him for his comments.

Ms. Margaret Frerking was recognized. Ms. Frerking stated she recently retired from the position of Associate Chief Engineer at the Jet Propulsion Laboratory and she remarked that what she sees from Dr. Kirk's report is a great deal of scatter in the data. She stated she had two inquiries, the first concerns the basis of the scatter and if it a telltale sign of something unexpected, and the second why not also retrieve Capsule A as plans are in place to retrieve Capsule B, as this would give two additional data points and reduce the scatter. Dr. Kirk replied as to the source of the scatter, in his work for ASTM data has been reviewed from worldwide databases and two-thirds of the scatter is related to the experimental uncertainty of establishing the T_41jvalue from fitting the Charpy data and he described this, given the amount of specimens available, as an inherent uncertainty. The remainder of the uncertainty in Dr. Kirk's opinion is due to lack of fidelity in simple engineering models to represent the underlying complex physics. He pointed to the embrittlement trend curves as evidence that progress has been made as the curves now account for the effect of fluence on more elements, not only copper and nickel but also manganese and phosphorus in product form although he commented the difference produced by phosphorus or manganese is very small. From an engineering viewpoint Dr. Kirk stated he is not hopeful much improvement is possible from this point and the fact remains that the greater part of the scatter is a function of the fact the Charpy tests are testing only eight to ten specimens. Dr. Kirk concurred with Ms. Frerking's observation that the model uncertainty was approximately 40% and he remarked that for a regulator the solution is drawing an upper bound curve to have a lot of margin. Dr. Kirk replied concerning removing Capsule A that DCPP would need to make a decision as to the value in continuing to keep Capsule A in the reactor and having that data available and he confirmed that Capsule B has a very long lead time and the NRC guidance is that it should be removed when the fluence exceeds twice the fluence that's projected at sixty years, which for DCPP Unit 1 is by 2028. Dr. Kirk reported Capsule A has a much lower lead factor so it can remain in the reactor for a time and still remain relevant.

Mr. Bruce Severance was recognized and stated that he is a member of the Diablo Canyon Decommissioning Engagement Panel, but was speaking individually. He stated he first started reading accounts that there was severe embrittlement in Unit 1 due to metallurgical flaws when he joined the DCDEP and when he asked for the fluence reports that were submitted with the 2009 LRA he was told that the current Westinghouse reports were confidential and that Westinghouse would not release them because they were confidential for the proprietary mathematical formulas they contained. He stated he later found that that was not true. He commented the Mothers for Peace group had to submit a Freedom of Information Act request in order to get access to the documents. Mr. Severance said that last June he called the NRC and spoke with a clerk who told him the NRC must never have gotten the documents and Mr. Severance remarked he would like PG&E to identify the documents it considers to be proprietary.

Mr. Severance thanked the Committee for engaging Dr. Kirk and for committing much time and energy to taking a close look at embrittlement. Mr. Severance reported he worked as a Regulatory Compliance Engineer for the Vice President of Engineering for North American operations at the Mitsubishi firm for many years and as he is not a nuclear physicist or engineer he approaches addressing his concerns from a regulatory perspective through looking for inconsistencies in the data in the historic record and he reported he has found many such inconsistencies. He remarked after an amicable conversation with Dr. Kirk he hopes to have an opportunity to review the inconsistencies he has identified with Dr Kirk.

Mr. Severance stated it was recognized early on that there were metallurgical deficiencies in the Unit 1 vessel and it was anticipated early on by Westinghouse and PG&E that Unit 1 would not have the same durability and projected lifespan as Unit 2. He remarked there is no limiting weld in Capsule A and only Capsule B contains the "27204 specification" that is the subject of his concern and it appears to Mr. Severance from the record that it doesn't contain entire samples. He stated his belief Capsule B contains some of the broken samples from Capsule S, and it has something in it called nozzle dropout which may be leftover scraps from a manufacturing process and there is a proposal written in document 92-072 that these be reconstituted after they have been irradiated which is unknown to Dr. Macdonald, but which Dr. Kirk reported could involve having tabs welded. Mr. Severance remarked he supports the idea of micro CT[25] testing if the DCISC believes that to be the most reliable method and he does not care if testing involves nanoindentation. He commented that by 1992 PG&E could not even get this [weld] material sample as a specification had been erased such that they were only able to get fragments to include in one of the four supplementary capsules that were inserted into the reactor at that time. He stated Capsule B is the only capsule in position at 45 degrees where it receives the highest fluence and data from Capsule S and Capsule V both indicated strongly that there is a pattern and the RT_PTSvalue for one was at 258°, the other was at 250.9° Fahrenheit and at the end of the Capsule V report there is a reference to letter, DCL 03-052, which states in the introduction that PG&E deemed the Capsule V data to be credible, which Mr. Severance said is not consistent with what Dr. Kirk said but PG&E was applying the new CT graph software model to the Capsule Y data and because of that application PG&E found it was two degrees out of range, which Mr. Severance stated was like 6% out of range for the limiting weld material. He remarked there are data points at 258° and 250.9° and in 2003 PG&E said the data was not credible and would try to invalidate it but PG&E only mentioned this in an appendix. In 2006 Mr. Severance reported PG&E realized it wanted to seek a 37-month extension and stated something akin to "well, wait a minute, maybe it is credible. We want this extension, so we're going to regard it as credible."

Mr. Severance stated PG&E then provided a recalculation such that instead of 32 effective full power years (EFPY) having a mean of around 254°, which is within 6% of the maximum of 270°, PG&E projected that it would be 257° by 35.2 EFPY which Mr. Severance stated runs to approximately 2024, so this represents the difference in the EFPYs and he observed that this is the difference between ending the license at September 2021 versus 2025. Mr. Severance reported the NRC's calculation determined the number that was 258.8°. He commented if one looks at the full change, the range from negative 56° of the unirradiated material, you have a "runway" of 326° with only 11° left before hitting the maximum in November of 2024. Mr. Severance remarked he believes that this is the plant's current status.

Mr. Severance remarked he does not understand Appendix D of the Capsule V report wherein there is a table showing the credibility of the different data sets and PG&E has stated you must have two sets of credible data for each limiting material, but the table shows there are two sets for each limiting material and immediately following the table it is stated "therefore all of our data is not credible" which Mr. Severance commented is completely contrary to what is stated by RG 1.99 and 10 CFR 50 and he stated he does not believe that the regulations were followed in this case as the data cannot be said to be credible, then stated not to be credible, and then stated to be credible again. He observed this situation occurred without the datasets changing and there was what he described as waffling that went on four different times and he observed this raises for him a serious concern about how PG&E reached its conclusions at various points in time.

Mr. Severance cited a document he stated was the NRC's approval in 2006 of the 37-month extension that allowed Unit 1 to run until 2024 and he commented this document states that the request to recover the testing time for DCPP Unit 1 amends the projected withdrawal for Capsule B to approximately 20.7 EFPY, when the capsule is projected to achieve a neutron fluence of 2.9 x 10 ¹⁹. Therefore, he stated the approval of the 37-month extension recognized the neutron fluence complies with the criteria for a four capsule withdrawal program. Mr. Severance remarked this supports his belief that PG&E was supposed to remove Capsule B in 2009 but it did not do so. He observed PG&E asked for an extension to defer removal of Capsule B until 2010 and then did so again in 2012 and the NRC allowed PG&E to do this on the basis of the table he referenced.

At this point Mr. Rathie remarked Mr. Severance's comments had taken the full ten minute time limit set aside for his comments. Mr. Rathie remarked in response to Mr. Severance's assertion that the Committee had denied him the ability to use PowerPoints during his comments that this was untrue and the Committee policy is to allow the use of visual materials by members of the public with the caveat that those materials do not negatively affect the computer the Committee uses for its public meetings. The Chair suggested that Mr. Severance submit his remaining remarks to the Committee in writing. Mr. Severance replied that in many ways he believes Dr. Kirk's report has dismissed his concerns and he hopes to have an opportunity to further discuss his concerns with Dr. Kirk.

Ms. Sherry Lewis of Mothers for Peace was recognized. Ms. Lewis stated the DCISC has been in the past very generous in its practice of letting members of the public speak at length and she asked why in this situation Mr. Severance was not being allowed to continue to speak. Drs. Peterson and Lam stated they were persuaded by Ms. Lewis' comment and Mr. Severance was invited to continued addressing remarks to the Committee.

Mr. Severance continued his remarks and commented that he has dedicated a great deal of time to his research and has analyzed approximately 4,000 pages of NRC documents and believes he can provide real value to the DCISC and Dr, Kirk. Mr. Severance commented he finds much of what Dr. Kirk has written is accurate and correct and he has an affection for things being correct. He commented he believes that Unit 2 is fine and he questions why an investment should be made of $1.4 billion in two reactors for five years when one reactor could be run for ten years for one-half this amount. Mr. Severance stated he looks at this issue from not just a safety standpoint, but also from the viewpoint of financial risk to both the state and the ratepayers. He confirmed he realizes that the Committee somewhat divorces itself from financial concerns but he does not believe continuing to operate Unit 1 is "a good bet" and Mr. Severance said he differs with Mothers for Peace and he is not an anti-nuclear person and believes if he were to sit down with Dr. Kirk all of his concerns and what he sees as anomalies could be addressed.

Mr. Severance addressed what he described as his next issue, that being the comparison of Table T6 in Part 2 of Dr. Kirk's report with its references to the credibility analysis of all the different capsules and Mr. Severance stated for some reason the results of Table T6 are exactly opposite to Table T2, Capsule B report, appendix D, HD 5, and he does not understand why, as the data addresses credibility and he remarked one analysis says Capsule S is not good for the limiting material, the other analysis says, no, it's Capsule Y and B, or you know, they're opposite. He stated this needs to be investigated.

Mr. Severance stated he began looking at the USE value and he remarked at the very beginning of the Capsule Y report it says the USE is predicted to be 66 foot pound and ten years and later the reports say USE is 66 foot pounds. Mr. Severance stated if one looks at the tables in the appendix of the Capsule D report, Table C1 in Appendix C states Capsule Y USE was only 60 foot pounds and he questions the inconsistency in how those data is reported and if those data are used graphically whether the scatter and the credibility determination might be different and he commented different data reported in supposedly the same dataset may explain some of the issues he has with credibility. Dr. Peterson remarked if there are different reports for the same samples that have different numbers then it is important for the Committee to determine which number is correct and to use that number. Mr. Severance commented he has theories for this including that it may be due to the application of the new "CV graph"[26] to the best fit curve approach and this was reactively done on the report from ten years earlier. Mr. Severance questions if one is fitting the best fit curve and has a critical data point on a limiting material, is the curve allowed to push the datapoint or must it stay close to things that are known?

Dr. Kirk inquired if Mr. Severance said Capsule D had an upper shelf energy of 66 foot pounds and Mr. Severance confirmed this was his statement based on the text in the introduction. Dr. Kirk observed the only way to resolve Mr. Severance's many questions would be to sit down and go through them line by line, but Dr. Kirk stated in this particular case he believes what Mr. Severance is doing, as the data from each capsule does not change, is Mr. Severance is reading the predicted values and he reported those can change based on the data that you use in the prediction and based on the credibility criteria some data are in and some are out, so the predicted values can change.

Mr. Severance asked if Dr. Kirk feels that the micro CT procedure, reconstituting and machining down as opposed to welding, is a credible procedure. Dr. Kirk stated reconstitution was extensively studied in the late 1990s and in the early 2000s there were extensive inter-laboratory studies done on how the tabs should be attached and what the weld input should be so as to prevent any changes in the properties and this has been codified in ASTM standard E-1253, so there should be no concern if that ASTM standard is followed to reconstitute the Capsule S inserts. Mr. Severance stated he would like to read the ASME standard and he inquired if there is an advantage to doing the micro CT with more samples such that the standard deviation is reduced because more trials are performed. Dr. Kirk replied that is not a simple question and if you reconstitute the samples and test them as Charpy samples then everything fits into the existing regulatory framework and you get another T_41jvalue and another USE value and carry on with the standard analysis. Dr. Kirk remarked if many micro CT tests are performed there is regulatory precedent for that, but there's not an approved process. Dr. Peterson remarked a key element would be the challenges in comparing the data from the micro CTs to the data from the Charpy samples but if one could reconstitute and get additional Charpy data using these methods then that would be something that could be directly compared. Dr. Kirk replied that this is an option and there are advantages, but from his perspective if he were asked if it would be better to test samples as reconstituted Charpy samples or to test them as micro CT samples this would be a difficult determination.

Mr. Severance inquired if the Committee would consider testing the samples or the fragments of samples that are remaining from prior testing. Dr. Peterson replied the Committee would be able to develop some recommendations and he believes at this point he has a good understanding of the basic areas of concerns that Mr. Severance is raising and he does not believe it to be possible to cover all of them in the context of this public meeting and a different process will need to be developed to try to make that happen.

Mr. Severance thanked the Committee for allowing him the extra time to speak as he has dedicated thousands of hours to his inquiries and he cares about the community, the ratepayers and the taxpayers and he believes the prudent decision would be to operate Unit 2 for ten years and he stated he would now step aside and let someone else speak.

Mr. John Geesman representing the Alliance for Nuclear Responsibility was recognized. Mr. Geesman remarked the embrittlement issue is one in which his client has no particular expertise or chooses to engage, as the Alliance for Nuclear Responsibility focuses its efforts on the concerns of state agencies and this issue will be resolved by the NRC. He observed the DCISC is a creature of state government and state law and to his knowledge no state agency is pressing the Committee to rush into a decision or a recommendation on the topic of the embrittlement of Unit 1. Mr. Geesman stated he found Dr. Kirk's presentation to be impressive and stated he believes the DCISC owes Dr. Macdonald the opportunity to present his version and the Committee should protect its credibility and not get in front of the data and therefore should wait for the Capsule B data before making a conclusive recommendation.

Ms. Kathy DePerry, a citizen of San Luis Obispo, was recognized. Ms. DePerry stated Dr. Kirk's report presented theories and projects which are not evidence. Ms. DePerry suggested the DCISC should wait for the capsule to be removed to learn the real data. She commented the DCISC is "all about nuclear power" and wants it to continue and will do whatever it has to do to change the data or the graphs to "make it look right" and it is all theory and speculation. She questioned if the Price-Anderson Act[27] were to be overturned would the citizens get to sue the members of the DCISC personally? She remarked the DCISC is making decisions for people in the community who have been subject to being spewed with radiation and are being asked to pay for an embrittled reactor that should have been shut down a long time ago.

Ms. Linda Seeley was recognized. Ms. Seeley stated she is greatly concerned about Capsule B because of Mr. Soenen's presentation that in its prior attempts DCPP was unable to remove it. She remarked DCPP knew ten years ago there were problems removing Capsule B and yet it turned out to be a different problem from what the plant believed it to be. She stated Capsule B appears to be a very important item in terms of extending the life of DCPP as Dr. Kirk has reported numbers could change when Capsule B is removed and tested. She remarked PG&E should not have had issues in 2023 with the tool used to try to remove Capsule B because they knew they were going to try again to do so and a contingency plan should have been in place. Ms. Seeley remarked it is her impression the Committee seems to be giving its approval for the plant to continue to run following expiration of the operating license from the NRC, which she believes expire in November 2024, on what she described as a conditional license. But, she commented that the results of the tests of Capsule B will not be available until 2026 with no assurance the reactor vessel will not have a terrible accident, including taking into account new data about seismic issues which puts the reactors at more risk. She closed her comments by stating she was impressed by Dr. Kirk's presentation but she urged the Committee to follow Mr. Geesman's advice.

Dr. Peterson stated it was helpful to hear from the members of the public and he recommended the Committee consider that Dr. Kirk's report as a very useful compilation of analyses and the report supports the conclusion that the NRC is very likely to conclude the license extension can be approved. Dr. Peterson also observed however, the DCISC has a basis to collect more data going forward and to see if there is any additional information or anomalies identified from Mr. Severance's work. Dr. Peterson suggested the Committee accept and endorse Dr. Kirk's report and direct ongoing investigation into this open area while continuing to engage Dr. Kirk's services to that end. Dr. Peterson remarked gathering more data will reduce uncertainty and he stated he believes the Committee should recommend that Capsule B be removed and the Committee should evaluate the opportunity to do additional testing and he believes the reconstituted Charpy tests may provide the best comparison. The Committee should then revisit this topic at its June 2024 public meeting.

Mr. Wardell remarked it is good that NRC regulatory approval appears likely for sixty years of operation, together with Dr. Kirk's confirmation that PG&E has done the correct analyses. However, Mr. Wardell agreed Capsule B will provide more data. Mr. Wardell stated he is not sure about the need for further testing but he believes Capsule B will answer many questions. Mr. Wardell remarked it would be useful for Dr. Kirk to complete the USE reanalysis as it could provide additional assurance regarding Unit 1 embrittlement. Mr. Wardell commented that just because a reactor vessel is embrittled it does not mean it is automatically going to fail as other things need to take place in addition to the physical state of the vessel, including cold water injection during high pressure. Mr. Wardell remarked the LTOP System discussed previously during this public meeting is in place to prevent the occurrence of those precursors and Mr. Wardell stated he is comfortable with Unit 1 continuing to operate but he would like to see the results of the testing of Capsule B and a reanalysis of USE.

Dr. Budnitz remarked regarding Ms. Seeley's remarks that she appears to believe there is a possibility that when Capsule B is removed and tested it may be found the Unit 1 reactor pressure vessel is so embrittled that it should have been shut down previously and must then be immediately shut down. Dr. Budnitz observed and Dr. Kirk agreed that this is a misreading of Dr. Kirk's report as whatever data comes from the testing of Capsule B it would only change the interpretation for twenty years of operation from today and would not call into question the integrity of the vessel as it sits today. Therefore, Dr. Budnitz stated it is not necessary for the Committee to take a position on an extended operational period of twenty years, but Dr. Budnitz stated that with what he knows today from Dr. Kirk's report the vessel is not going to be in an unacceptable condition for embrittlement within the next few years and it can continue to run for the next few years without a compromise to safety from the PTS phenomenon. Dr. Budnitz stated he offers this opinion with the caveat that he has not heard Dr. Macdonald's opinion. Dr. Kirk observed that whatever the tests of Capsule B reveal the results will describe the condition of the vessel after it would have operated for one hundred years and Dr. Kirk agreed with Dr. Budnitz interpretation and confirmed the impact of the Capsule B test data when it is available will be very minimal on operation of Unit 1 for forty plus years. Dr. Budnitz observed this data could potentially cast doubt on whether the vessel was good for sixty or eighty years of operation but not likely on whether it is good for five or ten more years.

Dr. Peterson made a motion, seconded by Dr. Budnitz, that the Committee accept and endorse Dr. Kirk's report and continue to perform further work to investigate and identify new information on an ongoing basis. Dr. Lam stated he was not persuaded as to the timing of a Committee endorsement of Dr. Kirks' report because the Committee has yet to hear from Dr. Macdonald and Dr. Hosemann may have some alternative means to bring forward, while Mr. Severance claims he has discovered that there are inconsistencies in the data and Mr. Geesman observed on the lack of state agency involvement and questioned the wisdom of the Committee getting in front of the data. Dr. Budnitz remarked that the concerns are safety-related and there is no need for state agency involvement before the DCISC can investigate and take a position. Dr. Peterson then amended his motion to state the Committee accepts Dr. Kirk's report and will continue to investigate the topic to gain new information from the sources identified as well as others and then return to this topic at the June 2024 public meeting to consider endorsing Dr. Kirk's report. Dr. Budnitz stated his second holds on Dr. Peterson's amended motion. Mr. Rathie remarked that the need for further investigation would normally be incorporated into the Open Items List and the Committee would need to provide further direction on Dr. Kirk's engagement. Dr. Peterson then asked that his motion be tabled until tomorrow for a vote and Mr. Rathie confirmed this was appropriate.

The Chair expressed the appreciation of the Committee to Mr. Soenen and Dr. Kirk.

XXI ADJOURN EVENING MEETING

Dr. Lam then adjourned the evening meeting of the DCISC at 8:45 p.m.

XXII RECONVENE FOR MORNING MEETING

The February 22, 2024, public meeting of the Diablo Canyon Independent Safety Committee was called to order by its Chair, Dr. Peter Lam at 9:00 a.m. This was the second day of a two-day meeting. Dr. Lam welcomed those persons attending in person and by Zoom Webinar and watching the proceedings on live streaming video. Dr. Budnitz was present and was attending remotely from his home office in Berkeley, California.

XXIII COMMITTEE MEMBER COMMENTS

Dr. Peterson commented the Committee held an important discussion during the evening session yesterday and having tabled the discussion intended to continue the matter later today.

XXIV PUBLIC COMMENTS AND COMMUNICATION

The Chair reviewed the invitation to address remarks to the Committee on matters not on the agenda for this public meeting and invited any comments from members of the public who wished to address the Committee to do so now.

Dr. Gene Nelson, senior legal researcher and President of Californians for Green Nuclear Power was recognized. Dr. Nelson read from an email sent earlier this day to the Committee's Office of Legal Counsel concerning Section 4.2 of the PG&E License Renewal Application (LRA) for DCPP from which Dr. Nelson in his message cited the vessel neutron embrittlement analysis and included it as an attachment. Dr. Nelson stated his belief the Committee and the public would benefit from Drs. Kirk's and Kadak's analysis and summary of Section 4.2 with a focus on identifying similarities and differences in the embrittlement determinations for Unit 1 and Unit 2. Dr. Nelson commented he believes Section 4.2 while it contains much information does not clearly communicate that information.

Mr. David Weisman representing the Alliance for Nuclear Responsibility was recognized. Mr. Weisman observed that in the DCISC fact finding reports words are used inconsistently in that some conclusions are couched using terms that results of the fact finding investigation appear satisfactory while other conclusions concerning results of the fact finding team's reviews are definitively stated and he commented he wonders whether this practice by the Committee is intentional. Mr. Weisman stated he believes this practice introduces an element of subjectivity into what might otherwise be objective statements as certain areas provide measurable metrics. Drs. Budnitz, Lam and Consultant Wardell responded and confirmed the distinction in the wording is intentional and the choice of words is determined based on the level of confidence by which the Committee makes statements in its reports. Dr. Lam remarked the fact-finding teams have only a finite period of time to review any issue presented by a team of PG&E technical staff and senior managers and Dr. Lam remarked the use of the term "appear" in his fact finding reports indicates to the reader a level of reasonable confidence in the fact finding team's conclusion. Dr. Budnitz commented that even with measurable and observable metrics, there is a possibility of error and in some cases the Committee's conclusions depend upon the nature and significance of the uncertainties imbedded in the metrics. Consultant Wardell confirmed the use of specific conclusory language in fact finding reports is intentional based upon these reports having been written by engineers and their subsequent review for technical accuracy.

XXV INFORMATION ITEMS BEFORE THE COMMITTEE (Cont'd.)

The Chair introduced and requested Mr. Blair Jones, DCPP Director of Strategy, Policy, Organizational Effectiveness and Chief of Staff to the Chief Nuclear Officer, to introduce the second of the PG&E informational presentations for this public meeting. Mr. Jones introduced DCPP Senior Director and DCPP Station Director Mr. Dennis Petersen. Mr. Jones reported Mr. Petersen holds a Bachelor of Science Degree in aeronautical engineering from California Polytechnic University at San Luis Obispo (Cal Poly) and has been employed at DCPP for more than 35 years. Mr. Petersen has previously held various leadership positions as Director of Operations Services, Director of Nuclear Work Management, Director of Learning Services, Director of Quality Verification and as an outage manager. Mr. Petersen spent the earlier part of his career in Operations and held a Senior Reactor Operator License.

Presentation on the State of the Plant including Key Events, Highlights, Maintenance Outage 1X25, Organizational Changes, and Other Station Activities since the DCISC's September 2023 Public Meeting.

Mr. Petersen remarked he no longer holds a license as a senior reactor operator and this would be his final presentation to the Committee as he will be retiring soon and his successor will be Mr. Justin Rogers. Mr. Petersen stated in his presentation he would provide a brief overview and update on station activity. He reported both DCPP units are currently operating at 100% power with all probabilistic risk assessment indicators and NRC Performance Indicators currently in Green status.[28] He reviewed recently completed activities during late 2023 and 2024 including:

→ Power reduced on both units to 50% due to Pacific Ocean high energy swell, cleaning (i.e., pick and dredge) and condenser backwash on December 28-29;

→ Completion of Unit 1 1R24 refueling outage critique on January 16;

→ Completion of Unit 2 2R24 refueling outage readiness review on January 17;

→ Completion of company-wide Safety Week focusing on use of human performance tools during January 22-26;

→ Completion of management-vendor meeting for 2R24 on January 29; and

→ Completion of the NRC Cyber Security Program Inspection on January 29-February 1.

In response to Consultant Kadak's inquiry Mr. Petersen reported the Pacific Ocean swells in late December were approaching 15 to 20 feet and long period swells of between 15 and 20 seconds from storm activity in the Gulf of Alaska generate considerable energy.

Mr. Petersen provided an update on emergency diesel generator (EDG) maintenance conducted during the first quarter of 2024 and reported DCPP has completed maintenance on EDG 2-3, maintenance is in progress and includes major inspections for EDG 2-1, and maintenance is scheduled for EDG 2-2.

Mr. Petersen reported San Luis Obispo County issued a tornado warning for the region on February 7, 2024, and DCPP entered its severe weather procedures. He reported the plant is designed and licensed to withstand external hazards including tornados and the effect of significant wind loading on buildings such that if necessary the plant can be safely shut down. He commented DCPP has operating procedures and emergency plans in place, including conducting walkdowns and securing loose materials and additional recovery equipment is in place and prepared if needed to respond to excessive wind and tornado conditions. He confirmed in response to Dr. Kadak's query that the plant is designed to withstand tornado missiles as well as severe wind.

Mr. Petersen reported that following 1R24 Unit 1 was shut down to address a small leak on a pressurizer safety valve and the valve was changed out and sent to the vendor for a forensic analysis as to why the leak occurred. He reported Unit 2 stayed near full power for 2023 except for a tunnel cleaning in November and in December. In response to Dr. Peterson's inquiry Mr. Petersen confirmed that prior to 1R24 there was a drop in power generation to keep the reactor parameters within specifications as he explained that with fuel planning if the unit is not taken offline during an operational cycle, it begins to run low on fuel by the end of the operational cycle and this can result in reducing load until the unit is shut down for a refueling outage. In response to Dr. Budnitz' inquiry Mr. Petersen replied that in almost all cases the power reductions were planned, and typically those that are unplanned are related to Pacific Ocean swell conditions. Dr. Budnitz commented unplanned shutdowns can often result in the start of an accident condition and can result from failure of a component. Mr. Petersen confirmed a reduction in power for Unit 2 in March 2023 was due to a break in a saltwater line at the Intake Structure which could have damaged a bearing for a circulating water pump and the power reduction was not planned. He remarked that INPO defines a planned outage as one planned 28 days in advance or more and he commented there is an exception for power reductions requested by the State of California grid operator which are also considered to be planned. Dr. Budnitz commented that prior to the accident to the Three Mile Island Nuclear Power Plant in Pennsylvania in 1979 the U.S. reactor fleet typically experienced approximately 1,000 unplanned outages each year and by year 2000 that number dropped to approximately 300 and today the entire fleet of 93 nuclear units experiences less than 100 unplanned outages each year.

In response to Consultant Wardell's inquiry Mr. Petersen replied that overall capacity factor data includes refueling outages.

Mr. Petersen reviewed certain of the activities which will take place during the remainder of 2024 as follows:

→ Nuclear Safety Oversight Committee (NSOC) visits on February 26-29 and June 24-27;

→ NRC License Renewal Inspections (2R24) – April 8-26;

→ NRC Inservice Inspection (2R24) - April 8-19;

→ NRC Radiation Protection Inspection – April 15-19

→ NRC License Renewal Inspection – June 17-21; and

→ NRC Age-Related Degradation Inspection – June 10-28

Dr. Gene Nelson of Californians for Green Nuclear Power was recognized. He observed Mr. Petersen's presentation showed a very high quality of plant operation and he congratulated Mr. Petersen on his retirement.

Mr. Bruce Severance was recognized. Mr. Severance stated he appreciated PG&E's staff for the coordination, effort and good work it takes to keep DCPP operating and commented he found the plant to be extraordinarily impressive when he visited in person.

Dr. Lam thanked Mr. Petersen for his presentation.

Mr. Jones then introduced the Director of Outage Management at DCPP Mr. Erik Werner and reported Mr. Werner has more than 20 years' experience in nuclear plant engineering including in the Engineering, Operations, Training, Decommissioning Planning and Outage Management organizations. Mr. Werner has been employed at DCPP for 18 years as a licensed senior reactor operator and holds a Bachelor of Science Degree from Cal Poly at San Luis Obispo.

Refueling Outage 1R24 Results (Including Initial License Renewal Inspection Results) and Preparation for Refueling Outage 2R24.

Mr. Werner stated in his presentation he would summarize performance during refueling outage 1R24, including license renewal inspection results, outage 1X25, and the preparations for 2R24. He summarized the outcome of 1R24 which he stated was planned as a 50-day duration outage including high level license renewal inspections that required outage conditions to perform. During 1R24 approximately 1,000 temporary workers were engaged. DCPP met the majority of the goals set, but experienced challenges in meeting the dose and reliability goals. In response to Consultant McWhorter's question concerning the dose goal Mr. Werner reported going over the goal was due to the work on the pressurizer valve as well as the large scope of the outage with more work activities which resulted in more items being discovered on the primary side[29] of the plant to be addressed in the outage. In response to Consultant Kadak's question Mr. Werner reported the 45 days required for 1R24 was approximately 10 days longer than recent outages, but not all the additional time was related to license renewal activities as the license renewal inspections were not all on the outage critical path and the few that were did not represent principal drivers of the extended time. He reported some items in the outage scope focused on plant reliability and long-term operation were on the secondary side in the Turbine Building.

Mr. Werner reported valve maintenance and containment fan cooler unit motor overhauls were main focuses of 1R24 on the primary side while on the secondary side high pressure Main Turbine inspection and valve maintenance were principal items. The 4kV and 480V vital electrical bus maintenance work was also completed as was the license renewal inspection of the Refueling Water Storage Tank. For the 1R24 project scope, the Intake Structure travelling screen frames were related to license renewal.

Mr. Werner reported outage 1X25 was a planned Mode 5[30] outage which took place in December 2023 to replace Pressurizer Safety Valve 8010B. He reported during 1X25 all goals were met for safety, human performance, outage duration, dose goal and reliability.

Mr. Werner gave a preview of refueling outage 2R24 which is scheduled for the spring of 2024. The outage is planned to take 50 days and will be very similar in scope to 1R24, encompassing scope for license renewal required inspections, planned maintenance and other refueling activities. Again, approximately 1,000 temporary workers will be engaged for 2R24 as was the case during 1R24. He reviewed the 2R24 outage goals which he commented were similar to those set for 1R24 and reported final goals will be established just prior to the start of the outage. He reported the dose goal for 2R24 is less than it was for 1R24 which he attributed to lessons learned in 1R24 and also a slight difference in the work on the primary side during 2R24. Mr. Werner observed a big contributor to lower dose goal for 2R24 is the plant will not be doing eddy current testing of the Steam Generators which he remarked was a fairly significant dose contributor during 1R24. Consultant McWhorter observed and Mr. Werner agreed Unit 2 also has a lower source term.[31] Dr. Budnitz observed the outage dose goal is established in person rem and there is a different dose goal for each person which at DCPP has never been exceeded. Dr. Budnitz suggested that a category be added to dose goal for "individual dose goal" that represents the amount of radiation received that no person should exceed. Dr. Peterson observed exceeding an individual dose goal represents a safety issue and does not really fit within one of the outage goal specific categories. Mr. Werner commented he appreciated and would take Dr. Budnitz' observation and suggestion into consideration and he reported radiation permits for entry into radiological controlled areas (RCAs) have appropriate dose limits which are well under the federal standards and also under the administrative levels set by the plant. In no case has any individual come close to any threshold, administrative or federal for dose exposure. He reported DCPP uses the As Low As Reasonably Achievable (ALARA) principles to challenge work practices to achieve the lowest dose for any work activity.

Mr. Werner reported the scope of 2R24 will include large motor overhauls on the primary side, valve inspection and maintenance on the secondary side, electrical 4kV and 480V Bus G maintenance, license renewal inspection of Unit 2's Refueling Water Storage Tank., and replacement of traveling screen frames at the Intake Structure. In response to Dr. Kadak's question Mr. Werner reported dredging of the Intake Cove will take place as a daily activity and is not part of the refueling outage. In response to Consultant Wardell's query Mr. Werner reported in 1R24 the majority of license renewal inspections were completed and 2R24 should have the same result, however, work on projects for long-term reliability has just begun and project work will be incorporated into future outages and may drive those outages to durations of more than 30 days. In response to Consultant Wardell's question Mr. Werner reported the focus of the project component of work during outages is to assure DCPP's ability with both units to support continued operation and reliable electrical generation for the state. In response to Consultant Kadak's inquiry Mr. Werner reported PG&E began planning in September 2022 after approval of SB846 and while there is no guarantee of operations beyond 2030 the decision-making model and long-range planning takes into consideration the possibility of operations proceeding past 2030 and having maintenance plans and projects in place. In response to Dr. Kadak's follow up questions Mr. Werner stated there are no deferred maintenance activities to be addressed as the frequencies for preventative maintenance remained on schedule during the period between 2016 and 2022 when the plant was expected to cease operation by 2025.

Ms. Sherry Lewis of Mothers for Peace was recognized. Ms. Lewis inquired as to how much an average temporary outage worker makes in wages for an outage and she also commented that the point of SB846 addressing five years of extended operation was a recognition that continued nuclear generation is only a stopgap. Mr. Jones and Dr. Lam responded and directed Ms. Lewis to make her inquiry concerning wage for the temporary workforce in the CPUC's general rate case proceedings. Mr. Jones remarked SB846 directed PG&E to do everything necessary for continued operation through 2030 and any operation beyond that date would need to have new legislative authority. He reported it is incumbent on PG&E now to ensure it meets the state's direction and to allow the state the opportunity to continue to bring other sources of clean energy to replace DCPP.

Dr. Gene Nelson of Californians for Green Nuclear Power was recognized and he reported as a temporary outage worker at DCPP in 2007 he received $26.00 per hour plus some fringe benefits. He reported the California Senate Committee on Energy, Utilities and Communication held a hearing recently during which Dr. Nelson testified and he has offered to speak at the California Assembly's Utilities and Energy Committee meeting on the issue of economical and reliable power.

Mr. John Geesman representing the Alliance for Nuclear Responsibility was recognized. Mr. Geesman commented in CPUC Decision 23-12-036 issued to extend the retirement dates for DCPP the CPUC Commissioners made findings and conclusions of law that the Commission lacked the evidentiary basis to make a finding that the extension of DCPP would be cost-effective, prudent, or reasonable. He reported PG&E is directed to file by March 29, 2024, a complete and transparent forecast for Commission approval of the costs that it expects to charge ratepayers. He observed that cost is still very much in play and in last year's proceeding PG&E revised its cost forecast upward by approximately 54% during the course of the proceeding.

The Chair thanked Mr. Werner for his presentation and the members of the public for their comments.

The Committee then took up their discussion of the Report on Unit 1 reactor pressure vessel integrity prepared by Dr. Mark Kirk. Dr. Lam asked for comments from the Committee's legal counsel.

Assistant Legal Counsel Rathie observed Dr. Kirk's report was prepared at the behest of the Committee and has been reviewed individually by the Members of the DCISC and their comments have been received and the report has been on the Committee's website for members of the public to review. Mr. Rathie stated it was his view it would now be appropriate for the Committee to accept the Report, that is, to receive the report with consent and in that context the ratepayers and citizens of California at this time deserve to hear from the Committee on the endorsement of the report's conclusions. Mr. Rathie observed that this would not represent the conclusion of the Committee's review of this matter as the review will continue, including considering input from Mr. Severance, Dr. Macdonald, Professor Hosemann and possibly others as well as the data from Capsule B when it is withdrawn and tested. He observed as the report would then be a part of the 34^th Annual Report the Committee would have the opportunity to draw its own specific conclusions in its approval of the Annual Report. He stated his recommendation was for the Committee to accept the report and endorse its conclusions and direct the Technical Consultants to draft an open item for issues to be followed, recognizing there is an opportunity for further consideration and conclusion based on information which may be received between now and the approval of the Annual Report.

Dr. Peterson stated he concurred with the approach described by Mr. Rathie and it is important to discuss the upcoming activities to be pursued through the Open Items List. Dr. Peterson commented he found Dr. Kirk's presentation, along with his review of the report, to be very helpful in allowing a better understanding of the set of issues associated with vessel embrittlement and the use of the samples placed in the capsules in the reactor and in the sister reactor in order to quantify the temperature at which the material transitions from being ductile to brittle which he described as probably the most important parameter in terms of an analysis of pressurized thermal shock. Dr. Peterson stated he agrees with the conclusions in the report and is prepared to endorse them provided the Committee has an open item to continue its review and to collect additional information. Dr. Peterson observed the history of what was done previously is largely superseded and the Committee's focus now needs to be on the current conclusions reached in Dr. Kirks' report and anything that might cause the Committee to modify those conclusions. He commented Dr. Kirk's conclusions are based on data that with inclusion of sister plant data covers a greater than sixty year period for the limiting weld material and one can interpolate that there is significant margin based on the analyses and screening criteria that one can conclude the plant is currently safe and is likely to be safe at least for the next five years of operation. Dr. Peterson stated he believes input should be received from the external stakeholders, in particular Mr. Severance and Dr. Macdonald as an open item and Dr. Kirk should be requested to identify an approach to obtain this data and this would be one of the open items to be reviewed at the June 2024 public meeting.

Dr. Peterson stated he also considered, in terms of a potential recommendation, whether the Committee should recommend additional testing on the existing materials removed from the capsules and Dr. Peterson stated he has concluded there is probably not sufficient value in doing additional testing. He stated he has concluded it is quite important that Capsule B be extracted during the upcoming refueling outage and its data analyzed and added to the existing database. Dr. Peterson stated his belief it would be very valuable to have Dr. Kirk perform an analysis that would assume a range of data from that test and to determine the likelihood that the results would change the current conclusions.

Dr. Lam stated he was not persuaded that the Committee should endorse the report. He remarked he believes it is appropriate for the Committee to accept the report and defer consideration of endorsing the report until receipt of additional information from Dr. Macdonald and Professor Hosemann and upon the receipt of the data from Capsule B and a final review from Mr. Severance. Dr. Lam stated he is hesitant to endorse the report in case Capsule B's results turn out to be a surprise and he speculated that the conclusions in the report will require adjustment. He stated his view that the Committee should accept the report as is and consider endorsing it when more information is received.

Dr. Budnitz observed it appears the Committee is divided and he was prepared to offer two [substitute] motions [to Dr. Peterson's motion of last evening], the first motion being to accept Dr. Kirk's report, and a second motion to endorse the conclusions in the report. He then moved that the DCISC accept Dr. Kirk's report and received a second to his motion by Dr. Peterson.

Ms. Sherry Lewis was recognized and commented she believes accepting the report is appropriate and although she has not read Dr. Macdonald's report it is her understanding Dr. Macdonald has several objections to certain parts of Dr. Kirk's report.

Dr. Gene Nelson of Californians for Green Nuclear Power indicated his support for accepting the Report.

Mr. Bruce Severance stated he completely supports accepting the report and he has had amicable discussion with Dr. Kirk and Dr. Kirk seems to him to be extremely knowledgeable and open to collaboration. He stated he has read Dr. Macdonald's report and he believes it is approximately 90% complete and in it Dr. Macdonald found many concerns Mr. Severance has not previously investigated which point to possible errors on inputs and as he has indicated, misstatements concerning the historical record. Mr. Severance stated he is willing to travel to New Hampshire where Dr. Kirk resides and work with him on refining possible misstatements of historic fact in the same manner as PG&E was allowed to have that opportunity which Mr. Severance believes appears extremely biased. Mr. Severance stated he would like the report to be endorsed when there has been an opportunity to get Dr. Macdonald's comments and he does not believe the Committee should rush its endorsement.

The Committee Members then unanimously approved accepting Dr. Kirk's report.

The Committee then took up consideration of endorsing the conclusions as stated on pages three through five of Part 2 of Dr. Kirks' report.

Dr. Lam suggested relative to the motion of endorsement suggested earlier by Dr. Budnitz the addition of a sentence be added to the motion qualifying that the endorsement is made before the Committee received comments from Professor Macdonald, from Professor Hosemann and from Mr. Severance.

Dr. Peterson referred to the work the Committee will be undertaking in accordance with the Open Items List and he stated it is quite important to reach a conclusion on what the Committee will request of Dr. Kirk in terms of taking input from key external stakeholders, those persons being Dr. Macdonald and Mr. Severance and possibly Professor Hosemann. Dr. Peterson observed the question to be addressed is the current state of embrittlement and he observed Dr. Kirk's report leads to the conclusion that the current state is within regulatory limits and the plant is therefore safe to operate. Dr. Peterson remarked he does not believe the history around regulatory compliance and previous positions are relevant to the Committee's inquiry as to the current state of embrittlement. Dr. Peterson observed the data from Capsule B will not be available in June 2024 and he suggested the Committee can consider a recommendation that PG&E should remove Capsule B during the upcoming refueling outage and extend the outage if necessary to do so.

Dr. Lam stated he fully concurs with Dr. Peterson's comments and he believes the plant fully complies with NRC regulations regarding PTS. But Dr. Lam believes the issue concerns the Committee's engagement of Dr. Kirk to address public concerns expressed to the Committee and he sees this as different than an assessment of the compliance with NRC regulations and it is incumbent upon the Committee to listen to Dr. Macdonald, Professor Hosemann and Mr. Severance and to see the results of Capsule B as this is a different matter than considering the condition of the facility.

Dr. Peterson remarked that in this case the regulations have both a screening criterion and a method for evaluating data built in and it is his assessment that achieving regulatory compliance means the plant is safe to operate due to the conservatisms and methods used and therefore the key question becomes a question of current regulatory compliance and it is incumbent on the Committee to review whether there may be data in Dr. Kirk's report which is inaccurate. Dr. Peterson emphasized his view that the historical record from the period when less data was available is not relevant to this key question.

Consultant Kadak agreed that public comment is very important and he observed Dr. Kirk's report has been available on the Committee's website now for one month. The Committee has had the opportunity to review Dr. Macdonald's Declaration and address comments in that document and to read and review Mr. Severance's numerous emails, comments and reports and all the above are reflected in Dr. Kirk's report. Data from the report has been supplied and verified by PG&E and Westinghouse. Dr. Kadak commented to date there has been no evidence or information presented of any errors in Dr. Kirk's report. Nothing will be known concerning the data from Capsule B for several years and Dr. Kadak stated he did not believe the Committee should wait that long to make a statement that the plant is safe to operate with regards to embrittlement. When data is available for Capsule B it can be assessed and appropriate modification made should they disprove the assertion that the plant is safe to operate for sixty years. Dr. Kadak observed the data from Capsule B will indicate the condition of the vessel at eighty years of operation not sixty. Dr. Kadak closed his remarks by stating making an endorsement subject to additional studies and findings would be appropriate at this time and any updates in the future can reflect the outcome of any discussion between Dr. Kirk, Mr. Severance and Dr. Macdonald.

Dr. Budnitz stated that in his long career whenever he has made a technical evaluation it is never final in that as new information is received it is assessed and evaluated against the previous conclusions, actions or even recommendations to determine if these were or were not appropriate based on the new information. Dr. Budnitz stated he has studied and evaluated the information received from Mr. Severance and the document submitted by Dr. Macdonald to the NRC docket and he remarked he has looked at those documents and the information in light of Dr. Kirk's report and in light of his own separate evaluation of Dr. Kirk's report and the history of previous inquiry into the matter which goes back to the 1980s. Dr. Budnitz stated he has come to a conclusion that supports offering a motion which he then made that the Committee endorse the conclusions of pages 3, 4 and 5 of Part 2 of Dr. Kirk's report and that the Committee should do all it can to hear and evaluate any other input it may receive between now and the June 20-21, 2024 public meeting and then revisit the endorsement at the June meeting.

Dr. Peterson commented that given a contingent endorsement it would be better to defer a decision on making an endorsement to the June 2024 public meeting and in the meantime focus on seeking additional information that could cause conclusions as to the current state of the plant and its future safety to change in the interim and return to the matter at the June public meeting.

Dr. Budnitz remarked if one accepts Dr. Kirk's conclusions concerning the embrittlement phenomenon the plant is certainly safe to run for several years and based on his reading of Mr. Severance and Dr. Macdonald's reports Dr. Budnitz has concluded the plant is certainly safe to operate for the next five years and Dr. Budnitz stated his opinion that it is important for the Committee to say that now. He remarked that last night a member of the public stated she concluded from Dr. Kirk's remarks that this was not so and the plant could be in immediate danger and Dr. Budnitz remarked in his view it is important that the members of the public understand that there is nothing he has seen that would challenge the conclusion the plant is safe to run for the next few years relative to the phenomenon of pressurized thermal shock. Dr. Budnitz further stated his view that he does not believe the data from Capsule B would change that conclusion and he believes the Committee owes it to the public to go on the record now and state its belief that Dr. Kirk's conclusions are correct while remaining open to new information.

Dr. Peterson remarked that any endorsement at this time will be contingent upon additional input between now and June and in his view, given the ambiguity, it is not necessary for the Committee to now adopt the motion suggested by Dr. Budnitz. Dr. Budnitz commented he can accept Dr. Peterson's position provided that the public has now heard from him and infers that the Committee agrees with him on the safety of the plant for the next few years. Dr. Lam stated that he believes the plant is certainly safe to continue operating until June and a timely motion for endorsement should be made in June. Dr. Peterson observed Dr. Budnitz' motion will not move forward, however, the Committee is committed to return to the issue in June. Dr. Budnitz then withdrew his motion which was not seconded.

In response to Dr. Peterson's request Dr. Kirk stated that he is not available to attend the June 20-21, 2024, public meeting either in person or remotely. At Dr. Peterson's request Dr. Kadak confirmed he believes he will be available to attend the June meeting and he reviewed the Committee's "asks" with respect to Dr. Kirk's report, those being: to receive from Mr. Severance and Dr. Macdonald their assessment of what is wrong with Dr. Kirk's analysis; determine if there is data that is incorrect or that was incorrectly provided by DCPP; to understand relative to Capsule B the prior attempts made to remove it and to investigate the plans for how the plant is planning on removing Capsule B during the next refueling outage and all identified options. Dr. Kadak also stated he recommends that the Committee investigate the contents of Capsule A to determine if it contains the weld material and the fluence level as to whether that information would provide information on the condition of the Unit 1 reactor pressure vessel for between forty and sixty years of operation. He remarked that although the Committee may not have all that data between now and June it is hoped that both Dr. Macdonald and Mr. Severance will provide their assessments and Dr. Lam added their assessments could include information from Professor Peter Hosemann. Dr. Peterson remarked this will give time for additional comments to be submitted but those comments must be focused on what might change the conclusions of Dr. Kirk's report and not on other matters. Dr. Budnitz commented the review of the License Renewal Application also provides a parallel activity as the document contains information on embrittlement and the NRC staff may pose questions to PG&E. Dr. Kadak raised the issue of continuing the matter until the October 2024 public meeting and Dr. Peterson replied that a decision need not be taken now as to whether to schedule this matter for the June or the October 2024 public meeting and it would be prudent to preserve flexibility in the matter of scheduling based on what is learned.

In response to the Chair's inquiry, Mr. Rathie stated that as public comment on this matter was received the previous evening, the state's Bagley-Keene Open Meeting Act does not require another opportunity for public comment on the matter.

The Chair then asked Mr. Blair Jones to introduce the next speaker. Mr. Jones then introduced the DCPP Director of Risk and Compliance Mr. Jordan Tyman to make the next presentation concerning the NRC's assessment of plant performance. Mr. Jones reported Mr. Tyman is responsible for oversight of the Risk Management Program, also known as Regulatory Services and Emergency Planning. Mr. Jones reported Mr. Tyman has been employed by PG&E for more than seven years and spent ten years prior to coming to PG&E at Westinghouse Electric Corporation in support of a number of its subsidiaries. Mr. Tyman holds a Degree in Mechanical Engineering from the University of Massachusetts.

Update on the Status of NRC Performance Indicators, Licensee Event Reports, NRC Inspection Reports, NRC Current Issues, and Current and Future License Amendment Requests.

Mr. Tyman commented in his presentation he would include the status of NRC oversight of DCPP from September 2023 to February 2024. Mr. Tyman stated the period covered by his report includes approximately 2,000 hours of NRC inspection time including by the two on site resident inspectors who live and work in the local community and Mr. Tyman described this independent oversight by the NRC and the DCISC as critical to DCPP's success in continuing to provide reliable power. During this period there were five routine programmatic NRC inspections. All violations received since September 2023 were of very low safety significance and DCPP has continued to meet the requirements to remain in Column 1 of the NRC's Reactor Oversight Process (ROPs) Action Matrix. All sixteen NRC Performance Indicators assessed monthly are within Green[32] parameters.

Concerning the violations received Mr. Tyman reported they fell within three categories which he identified and discussed as follows:

→ Procedure use and adherence - Mr. Tyman described this as centering around opportunities for continuous learning with respect to level of detail to be incorporated in certain of the 9,000 procedures guiding work at DCPP;

→ Opportunities to have more level of detail - Mr. Tyman provided as an example the heat sink (the Pacific Ocean) upper temperature allowed per Technical Specifications, but which exact temperature was not included in procedures; and

→ Enhance compliance controls - Mr. Tyman remarked within procedures there are opportunities to implement or incorporate controls as proactive preventative measures to add defense-in-depth and gave as an example the use of signage or human performance tools.

In response to Dr. Lam's question Mr. Tyman reported DCPP received eight low level violations between September 2023 and February 2024.

Mr. Tyman stated there was one licensee event report (LER) submitted by DCPP since the last public meeting of the DCISC in September 2023. LER 2023-001-00 was submitted on November 27, 2023, for a Unit 1 shut down in accordance with plant procedures during a preplanned outage while the unit was at approximately 11% power due to increasing water level in a non-safety related feedwater heater. In response to Consultant McWhorter's query Mr. Tyman reports a LER was required due to the manual trip.

Mr. Tyman reported on upcoming NRC inspections as follows:

→ Cyber Security Inspection – on-site inspection activities completed in early February.

→ 2R24 Inservice Inspection – April 2024 (Unit 2 outage).

→ 2R24 Radiation Protection Inspection – April 2024 (Unit 2 outage).

→ License Renewal Inspections – April 2024 (Unit 2 outage).

In response to Dr. Lam's request Mr. Tyman described the Cyber Security Inspection as being very intense including a vertical slice of all programmatic aspects, technical controls and protection and preventative measures required under the NRC cyber security framework. The inspection generally lasts for one week and includes numerous requests for information. Dr. Peterson remarked while the DCISC has been briefed on cyber security the Committee recognizes DCPP cannot share certain security-related information and the DCISC focuses its attention on the interface and alignment between security and operational safety.

Mr. Tyman reported a License Amendment Request (LAR) was requested and issued for revision of Technical Specification 3.7.8 for the Auxiliary Saltwater (ASW) System to permit on a one-time basis an additional 72 hours for replacement of ASW Pump 2-2 motor. Mr. Tyman reported DCPP has ongoing LARs for Risk-Informed Technical Specification Completion Times, pending since July 2023; 10 CFR 50.69 Risk-Informed Categorization of Structures, Systems and Components, pending since September 2023; and a for a revision of Technical Specification 5.6. Pressure Temperature Limits Report, to include additional NRC-approved calculation methodologies for continued operation to be submitted in late February 2024.

Mr. Tyman concluded his presentation with the comment that DCPP continues to remain in the highest NRC regulatory performance categories and uses the Corrective Action Program to drive continuous improvement. The eight violations received were each of very low safety significance. In response to Dr. Lam's query Mr. Tyman reported the NRC evaluates regulatory performance under the Baseline Inspection Program conducted by the on-site resident inspectors, the programmatic inspections conducted throughout the year, and based upon the Performance Indicators.

In response to Consultant Wardell's inquiry concerning plans to implement an Integrated Public Alert and Warning System (IPAWS) Mr. Tyman reported DCPP does not presently use an IPAWS, but it is being evaluated in discussions with San Luis Obispo County and he confirmed Mr. Wardell's observation that implementation of IPAWS would be in addition to not a replacement of the present emergency warning siren system.

The Chair thanked Mr. Tyman for his presentation.

Ms. Brandy Lopez introduced Mr. Blair Jones and reported Mr. Jones is Chief of Staff to the Chief Nuclear Officer and Director of Strategy, Policy and Organizational Effectiveness. She stated Mr. Jones began his career with PG&E in 2009 and previously served as a Senior Manager in Marketing and Communication. Prior to coming to PG&E Mr. Jones worked for President George W. Bush and several members of Congress. Ms. Lopez reported Mr. Jones holds a Bachelor of Arts Degree in Communications from the University of Alabama.

Update on Proposed New Staff Retention Incentive Program in Support of Extended Operations; Results of the 2023 Operating Plan and Key Elements of the 2024 Operating Plan.

Mr. Jones began his presentation with a review of the results of the 2023 Operating Plan and remarked the approval of SB846 in September 2022 directing PG&E to seek to continue operation of DCPP until 2030 made 2023 a pivot year for the organization. He reported a great deal of time in 2023 was devoted to the transition to continued operations including hiring approximately 200 new DCPP employees and completing the 1R24 refueling outage with no safety or performance challenges. Mr. Jones stated that for the third successive year in 2023 DCPP maintained 100% availability during the peak summer electric demand period. He observed that the duration of the peak season continues to grow longer. Mr. Jones reported DCPP completed submittal of its License Renewal Application ahead of schedule and the Application has been found sufficient by the NRC which represented a considerable effort by the DCPP organization. He observed, as Mr. Tyman just reported, DCPP continues to be in Column 1 demonstrating high performance on the NRC's ROP Matrix.

Concerning Operating Plan results in 2023 Mr. Jones reported DCPP achieved 100% on the Reliability and Safety Indicator which he described as a key metric used industry wide. The plant achieved first quartile performance for the metric measuring Days Away, Restricted or Transferred Cases and in response to Dr. Peterson's query Mr. Jones reported there were zero cases under this metric. Dr. Peterson remarked the nuclear industry in terms of lost work days is generally an order of magnitude safer than other industries and Mr. Jones agreed and pointed to pre-planning briefings, de-briefings, identification of precursors, and observation of work in the field as contributors to the industry's good performance. Dr. Peterson remarked the evidence shows that the DCPP workforce continues to report injuries at a low level. In response to Consultant Wardell's request Mr. Jones explained the Days Away, Restricted or Transferred Cases metric accompanies the Lost Work-Day Cases metric as a measurement of the organization's commitment to worker safety.

For 2024 Mr. Jones identified focus areas aligned with PG&E's corporate strategy which include identification, recognition and alignment of an organization based upon purpose, virtue, and stands. He commented these principles are part of organizational decision making with the purpose being to identify the reasons for the organization's existence, virtues the recognition of who the organization is, and stands being what the organization is charged with delivering and to whom. Mr. Jones reported the organization's mission is to safely generate clean, reliable and affordable energy for California hometowns and he noted with the passage of SB846 DCPP will be delivering electricity to areas beyond PG&E's service territory. He remarked on the organization's recognition that it must earn the right to continue to operate each day, focusing on reliability but making safety the first priority.

Mr. Jones discussed what he described as the pillars to sustain a culture of excellence in generation performance including the rigorous use of performance improvement tools and the Corrective Action Program, excellence in equipment reliability, and safe and event-free operations. He observed that with change come challenges to keep a workforce aligned and to maintain focus and Mr. Jones reported these pillars have not changed for a number of years.

Mr. Jones described the Lean Operating System, a business model used throughout the world which PG&E Chief Executive Officer Ms. Patricia K. Poppe brought to PG&E several years ago. Mr. Jones remarked the Lean Operating System introduced new insights into programs, budgets and costs and its use at DCPP has been reviewed with the Committee during fact finding. He stated the Lean Operating System provides a vehicle for assessing how the organization is succeeding or falling short in achieving its goals and milestones in order to take appropriate and timely action. In response to Consultant Kadak's query Mr. Jones identified setting a target for the annual elimination of waste as including redundant or duplicative work and he confirmed it is a metric used to evaluate the effectiveness of the Lean Operating System.

Regarding an update on the DCPP Employee Retention Programs Mr. Jones reported that the first retention program, a seven year program which went into effect in 2016 was recently concluded. He described this program as very successful with a 98% participation rate for Tier 1 for 2016 through 2020, and a 95% participation rate for Tier 2 from 2021 to 2023. He reported with the passage of SB846 PG&E was directed to continue with an Employee Retention Program based upon extending the conclusion of operations by five years. Mr. Jones reported this five-year period is not seen as a long-term commitment, as positions at a nuclear power plant often require a considerable training period for new employees which is specific to an individual plant. He reported PG&E has filed an application for the extended retention program with the CPUC and a decision is anticipated to be issued sometime in August 2024. In response to Dr. Lam's inquiry Mr. Jones confirmed the retention incentive continues to be set at 25% of an employee's base pay which would be a continuation of the program which ended in 2023 and upon approval from the CPUC would be effective retroactively. He reported there would be no funds paid out under the continued retention program until March 2025. In response to Dr. Peterson's inquiry Mr. Jones stated the extended retention program is proposed to be broken into four tiers, with the first being from August 2023 to the end of 2024, the second tier would be for one year with the two latter periods being three years and two years respectively. Mr. Jones reported these tiers were proposed strategically in recognition of the fact a number of DCPP employees are approaching retirement and in light of the need for those employees to be available to transfer valuable institutional knowledge and to train new employees. In response to Consultant Kadak's query Mr. Jones replied the extended Employee Retention Program will be funded through PG&E's CPUC ratemaking cases and is unique in that all of the investor owned utilities in California will participate in various ratemakings to support the extended operation of DCPP including through the Employee Retention Program.

Mr. John Geesman representing the Alliance for Nuclear Responsibility was recognized. Mr. Geesman stated that the supplemental retention program described by Mr. Jones is unique from a ratepayer standpoint and while his client supports the program, including the 25% enhancement, he remarked the CPUC declined to consider the Alliance's challenge as to the source of payments for that retention. He commented it is his client's belief that the statute [SB846] provided taxpayer funds to cover at least the transitional portion of the supplemental payments. He remarked not only will all of the ratepayers in California be covering the additional cost but they will also be covering the cost for the tail of the past program from 2023 until the beginning of extended operations which means ratepayers in non-PG&E service territories will be paying these pass through charges before they receive any of the electricity produced by DCPP. Mr. Geesman closed his remarks with the observation the state is strongly behind the concept of supporting the DCPP workforce as is his client, but his client believes the ratepayers ought not to be responsible before they receive any electricity.

Dr. Gene Nelson of Californians for Green Nuclear Power offered congratulations to Mr. Jones for his presentation.

Mr. Bruce Severance, a member of the Diablo Canyon Decommissioning Engagement Panel, speaking as an individual, was recognized. Mr. Severance remarked he does not question the commitment to safety described by Mr. Jones and he believes good communication and humility are important aspects. Mr. Severance stated DCPP and Palisades were among the foremost embrittled reactors in the country and when he hears about a commitment to safety he finds an inherent difficulty in thinking all the various threads of communication are properly connected. Mr. Severance reported that in 2017 the firm of Black and Veatch, as consultants to PG&E, prepared a report entitled Historic Site Assessment on Safety with what he described as a long list of potential areas where safety concerns might occur at DCPP and he stated these areas need to be managed. He stated the report described 22 different instances where the report was not able to document the status due to data gaps. He remarked a discussion of safety should include returning to the Historic Site Assessment on Safety and filling in the blanks in that report. He reported he brought this issue to the attention of the Engagement Panel because he wants to see the best economic outcome for the community and he questions how DCPP assets can be repurposed if reports such as the Black and Veatch report are not complete as there are 500 different safety-related subsystems and components that could fail and each has to be monitored and he encouraged more thought be given to long-term planning for DCPP facilities. He closed his remarks by stating he would send a copy of the Black and Veatch Historic Site Assessment on Safety to the Committee.

Dr. Budnitz observed that in several of his PowerPoint slides on various metrics Mr. Jones made reference to DCPP performance being within the first quartile. Dr. Budnitz remarked with not quite 100 pressurized water reactors on some fifty or sixty sites that sounds like good performance by PG&E. But Dr. Budnitz remarked this might not be the case as perhaps even the best performing plants are not performing good enough or perhaps the worst performing plants are performing much better than any criterion of concern and he remarked this is the problem with metrics and peer comparisons as the question is really whether the distinction is meaningful, for example the statement made by Mr. Severance about DCPP and Palisades being embrittled could be better informed by information that while embrittled, both plants are very safe to operate than simply stating the plants are the most embrittled, as the statement without additional context is of insufficient value. With regard to DCPP Dr. Budnitz stated that what is important to him is not whether Unit 1 is the most embrittled reactor, but whether it has plenty of margin concerning embrittlement and he remarked he does not believe that this distinction is sufficiently appreciated in the recent discussions and he remarked the Committee needs to identify and adhere to criteria rather than relying on relative measures.

The Chair thanked both Mr. Jones and Dr. Budnitz for their comments.

XXVI ADJOURN MORNING SESSION

The Chair adjourned the morning session of the Committee at 12:10 p.m.

XXVII RECONVENE FOR AFTERNOON SESSION

The February 22, 2024, afternoon session of the Diablo Canyon Independent Safety Committee was called to order by its Chair, Dr. Peter Lam, at 1:25 p.m. Dr. Lam welcomed everyone to the afternoon session. Dr. Budnitz was in attendance via remote technology.

XXVIII COMMITTEE MEMBER COMMENTS

Dr. Lam requested any of the Members who wished to make remarks to do so at this time. There were no remarks by the Members.

XXIX PUBLIC COMMENTS AND COMMUNICATION

The Chair reviewed the invitation to address the Committee on matters not on the agenda for this public meeting and invited any comments from members of the public who wished to address the Committee to do so now. There was no response to this invitation.

XXX INFORMATION ITEMS BEFORE THE COMMITTEE (Cont'd.)

Dr. Lam asked Mr. Jones to continue with the informational presentations requested by the Committee of PG&E for this meeting. Mr. Jones then asked Mr. Philippe Soenen, Director of Strategic Initiatives at DCPP, to make that presentation. Mr. Soenen made an earlier presentation to the Committee during the evening session of this meeting.

Overview of New License Renewal Application Organization, Information Contained and Highlights of Sections with Significant New Information.

Mr. Soenen reported he would be discussing the dedicated team assembled for the development of the new License Renewal Application (LRA), the guidance documents followed for that effort, and any significant changes from the prior application as well as license renewal activities to be conducted in 2024.

Mr. Soenen stated SB846 directed PG&E to take all necessary steps to relicense DCPP for an additional five years of operation. He remarked this effort differed from that of other applicants due to the compressed period of time available and a team was assembled to undertake this task. He reported a new LRA was developed and submitted to the NRC on November 7, 2023, and DCPP received a determination of sufficiency from the NRC on December 19, 2023. Mr. Soenen stated the LRA was developed in accordance with NUREG 1801 documents, specifically the second revision of the Generic Aging Lessons Learned (GALL) document. As part of the development of the LRA the scoping and screening results from DCPP's prior LRA from 2009 were used as a baseline and updated based on changes to the plant, together with operating experience from other license renewals to ensure the appropriate aging mechanisms are identified for the Aging Management Programs. Mr. Soenen reported the same systems are in scope now as were in the scope of the 2009 LRA. Annual updates continued to be required while the 2009 LRA was under review including reviewing design changes and changes to the licensing basis and that process was taken and applied through a longer period for the current LRA with the application now having been updated through 2023.

Mr. Soenen reported the next major subset of the LRA process involves the Aging Management Programs and DCPP used information from the 2009 LRA including the requests for additional information, the safety evaluation reports and the open items and incorporated these into the 2023 LRA. He reported DCPP also reviewed recent license renewal applications by the Comanche Peak Nuclear Power Plant in Texas and the Waterford Steam Electric Station Unit 3, a nuclear power plant in Louisiana. He reported the guidance documents specifically refer to a review of five to ten years of operating experience and DCPP reviewed ten years' worth of operating experience to ensure there is nothing unique to DCPP as far as aging management.

Mr. Soenen reviewed the Chapters and Appendices of the 2023 LRA and any significant changes implemented since the 2009 LRA was withdrawn as followed:

Chapter 1 – Administrative Information, no significant changes.

Chapter 2 – Scoping and Screening Methodology – significant change identified with reference to DCPP transition to National Fire Protection Association Section 805 regulations.

Chapter 3 - Aging Management Review Results – updated to incorporate latest NRC guidance.

Chapter 4 - Time-Limited Aging Analysis – review of design changes including additional structural weld overlays in both units, ASME required additional crack growth and flaw analysis based on indications.

Appendix A - Final Safety Analysis Report Supplement – high level descriptions of aging management programs with no significant changes.

Appendix B - Aging Management Programs – based on new guidance documents, NUREG 1801 Revision 2, level of detail with changes for new programs for aboveground metal tanks, buried and underground piping and tanks, new periodic inspections for selective leaching, and four commitments planned for implementation by December 2028.

Appendix C - Commodity Groups - Not used at DCPP.

Appendix D - Technical Specification Changes - Not used at DCPP.

Appendix E - Environmental Report – has been completely redone due to the time which has elapsed elapses since the previous LRA was submitted in 2009. Mr. Soenen reported that due to the environmental assessments made for decommissioning for coastal resources and endangered or threatened species being similar and having been done recently the same information was able to be used for the 2023 LRA Environmental Report. Mr. Soenen reported public comments are still being received on the Environmental Report.

Mr. Soenen reported DCPP is on schedule to have 90%, that is, more than 700, of the inspections completed prior to entering the period of extended operation for each unit to demonstrate DCPP does not have anything unique or unexpected relative to aging mechanisms and the Aging Management Programs are able to identify effects of aging. He reported the deferral of other more risk-significant systems is permissible because those components are already under surveillance programs and are covered by other aging management programs. He remarked the main point of implementing these inspections is to be able to demonstrate to the NRC the basis for a determination that DCPP is safe to continue to operate while the NRC completes its detailed review of the 2023 LRA. In response to Dr. Budnitz' request Mr. Soenen identified the replacement of copper alloy piping in the plant's domestic systems as a non-safety related system for which repair is being deferred and which failure could have a negative impact or prevent a safety-related component from performing its function. He remarked this represents a license renewal commitment to replace the piping with either greater corrosion resistant material or provide a shielding so there can be no interaction with a safety-related component. Mr. Soenen confirmed Dr. Budnitz' observation that the technical basis for the extended implementation time is provided within the LRA.

Mr. Soenen concluded his presentation by displaying a graph with the NRC activities and the schedule. He reported for inspections performed during the Unit 1 outage, prior to the new LRA having been submitted, the NRC was on the site and performed inspections as well as reviewing documents and closing out previous commitments and the NRC will be reviewing what was previously completed and what is in the 2023 LRA. He reported an operating experience audit is now in progress and the NRC will be on-site next week for a scoping and screening audit for Unit 2 inspections that will be performed during the upcoming refueling outage. Mr. Soenen reported some of the NRC reviews are performed remotely and these are very intensive and involve breakout meetings with a great deal of detailed information reviewed. He reported annual updates of the LRA are required for any new information and there will be a public meeting scheduled specifically for the supplemental Environmental Impact Statement.

Dr. Peterson remarked in the past there have been issues with NRC and DCISC public meeting schedules and he wondered if there might be an opportunity to coordinate schedules such that meetings would not be on the same days. Mr. Soenen stated he would take note of Dr. Peterson's comment in the process of scheduling the public meeting on the Environmental Impact Statement. In response to Dr. Lam's inquiry, Mr. Soenen replied there are 44 separate Aging Management Programs some of which span multiple systems which experience similar environments and some of which are component-based and Mr. Soenen commented the Aging Management Programs are developed to be generically applicable to all nuclear sites. Mr. Soenen, in response to Dr. Lam's query, remarked that not all requests for additional information from the NRC reflect a deficiency, but each must receive a response and they tend to require clarification or resolution of inconsistencies to make sure of a clear understanding and he remarked that with the breakout meeting format DCPP expects to receive fewer requests for additional information. He confirmed that no requests for additional information have been received to date concerning the pending 2023 LRA. Dr. Budnitz suggested that members of the public interested in this topic may want to review the GALL Report, NUREG 1801, as it sets forth the logic used by the NRC in reviewing aging management of systems, structures and components at a nuclear power plant. In response to Consultant Kadak's request Mr. Soenen replied the reviews for the LRA process are very detailed and are conducted both from NRC Headquarters and from the Regional Office and the inspectors from the region perform inspections of specific components at the plant in person.

Mr. David Weisman of the Alliance for Nuclear Responsibility was recognized. Mr. Weisman inquired whether, in addition to the Environmental Impact Statement, Coastal Zone Management Act certification is required and whether that process overlaps with the proposed schedule. Mr. Soenen confirmed this Coastal Zone certification was required and a request was submitted in 2023, concurrently with the submission of the LRA to the NRC, and the process for the Coastal Zone Management certification will run in parallel with the LRA. Mr. Soenen reported the certification process is in the early stages and he stated the schedule for the review will be determined by the state's lead agency.

Mr. Bruce Severance was recognized. Mr. Severance stated he has reviewed the GALL Report and found it thorough and detailed and he was comforted that the data has been gathered from a broad range of different experience as this reduces uncertainty and provides better operating parameters. Mr. Severance called Mr. Soenen's attention to the Historic Site Assessment Report he mentioned previously and he referred again to the need to fill the data gaps in that report. Mr. Severance commented in terms of aging management it is extremely important to have accurate data concerning reactor vessel embrittlement including the possibility of needing to comply with 10 CFR 50.61a which he remarked would require additional mitigating measures to reduce the chances of thermal shock. He stated he fundamentally disagreed with a comment earlier during this meeting concerning the need for an understanding of the degree of margin against the effects of embrittlement and he repeated his statement about the importance of having sufficient data to understand the context of a problem and the appropriateness of mitigating measures. He stated he does not understand why, as operating conditions differ, even if nanoindentation testing, micro CT, or micro-Charpy testing is not endorsed by the NRC one would not try to gather more information in those categories and assess the standard deviations and uncertainties using alternate physical stress testing techniques for materials that have been irradiated. He referred to Dr. Kirk's report and observed Dr. Kirk, from his analysis projected Unit 1 would reach the maximum USE screening criteria with reference to embrittlement by 2029 and he remarked that was in contradiction to a report by Westinghouse.

Dr. Lam thanked Mr. Severance for his comments and asked Mr. Jones to introduce the next speaker. Mr. Jones introduced Mr. Jearl Strickland, presently serving as a consultant to PG&E but Mr. Jones remarked Mr. Strickland was employed at DCPP as an engineer for 43 years and in his capacity with PG&E oversaw the Seismic Program and the Spent Fuel Storage Program. Mr. Jones also introduced Dr. Chris Madugo and Dr. Albert Kottke of the PG&E Geosciences Department and he stated Dr. Madugo holds Ph.D. in Geoscience and Dr. Kottke holds a Bachelor's Degree in Geological Engineering and a Ph.D. in Civil Engineering.

Update on the Status of PG&E Sponsored Study Required Under SB846 for Conducting an Updated Seismic Assessment.

Mr. Strickland began his presentation by stating he would describe the overall process and then for the technical results of the Updated Seismic Assessment (sometimes the Assessment) he would turn the presentation over to Drs. Madugo and Kottke and Mr. Strickland would then return to the podium to provide closing comments.

Mr. Strickland began his presentation by reporting the NRC included as a condition of the initial operating licenses for DCPP that PG&E continue to study and evaluate seismic information and perform updated studies as necessary. In response PG&E developed and implemented the Long-Term Seismic Program (LTSP) in 1985 to satisfy that license condition and has staffed a Geosciences Department with experts to keep abreast of new geological, geophysical, seismological, and seismic engineering updates and lessons learned as well as to operate a strong motion accelerometer array to collect real time data that is shared with the U.S. Geological Survey (USGS) and other organizations through the Central Coast Seismic Network. Mr. Strickland reported PG&E is committed to continuing the LTSP for the duration of any extension of the operating licenses for DCPP.

In describing key takeaways from the recently completed Updated Seismic Assessment required by SB846 Mr. Strickland reported the Assessment was completed in January 2024 with no significant findings. He commented the Updated Seismic Assessment found that continued research since 2015 identified only minor changes in the source characterization of hazard-significant seismic sources, but no significant increase in the seismic risk. The Assessment found no new seismic information that would change the conclusions from the assessment conducted in 2015 that were reviewed and accepted by NRC following the accident at the Fukushima Daiichi nuclear power plant in Japan. The process and results of the recent Updated Seismic Assessment were independently verified by the Participatory Peer Review Panel (PPRP) and a panel from UCLA's B. John Garrick Institute for the Risk Sciences (the Garrick Institute).

Mr. Strickland reported the Updated Seismic Assessment was modeled after the NRC Senior Seismic Hazard Analysis Committee (SSHAC) process, as updated in 2018 and found in NUREG 2213, which includes a two-step evaluation and integration process that is focused on capturing the center, body, and range of technically defensible interpretations, robust peer review, and clear, transparent documentation. He reported this is the standard approach for conducting nuclear seismic hazard studies. Mr. Strickland observed the SSHAC process outlines specific roles and adhering to those roles is important for success of a project. A project Technical Integrator (TI) is at the center, gathering inputs and developing the model. The PPRP, made up of subject matter experts, remains engaged throughout the process and there are primary reviewers engaged to review the product. Mr. Strickland reported observers from the DWR and the DCISC were invited to and attended all the workshops allowing the regulatory bodies or other decision-makers to witness the process first-hand. Questions and comments were incorporated into project documentation. Mr. Strickland displayed an organizational chart for the project showing the various components of the project team.

Dr. Madugo stated that his background is in earthquake geology and he would be discussing the seismic source characterization portion of the Updated Seismic Assessment, following which Dr. Kottke will discuss ground motion, site response, and the results of the hazard evaluation.

Dr. Madugo reported the last evaluation [of seismicity at DCPP and its environs] was the SSHAC study performed in 2015 and since then there have been eight years of new data to evaluate. He stated the primary drivers for the seismic source hazards are the principal faults around the power plant, those being the Hosgri, Los Osos, San Luis Bay, Shoreline, and certain other faults including the connecting faults that link the primary sources and have a lesser impact on the seismic hazard, and the regional faults, such as the San Andreas Fault which is located far to the east. He reported the 2016 model has aerial sources for the Local, Vicinity, and Regional Source Zones to consider, catalog and account for the seismic sources that are not well constrained in terms of the data. Dr. Madugo commented in terms of impact on the hazard it is the local source zone that is the most important to DCPP. He described the sources as the key drivers for the seismic hazard to the power plant and the focus areas for the Updated Seismic Assessment.

Dr. Madugo reported in terms of the faults source review process, specific focus was placed on fault-specific models for geometry and slip rate and general information was reviewed for new methods in rupture and slip rate allocation, magnitude-recurrence distribution, and time dependency. In response to Dr. Peterson's query, Dr. Madugo stated the depth studies were conducted from twelve to fifteen kilometers and he stated this is the depth where seismicity dies out as the crust is no longer rigid enough to support large earthquakes. He observed earthquake magnitude is a function of the rupture area which for a large earthquake can extend from the depth to the surface. He displayed the three fault geometry models for the Hosgri, Shoreline and the Los Osos Faults. Those being the Outward Vergent, Southwest Vergent, and Northeast Vergent Models which Dr. Madugo stated take into account and represent the uncertainty in all the different types of data.

Dr. Madugo provided and described the following fault-specific matrix developed from new information in terms of the geometry of the faults:

Fault	Geometry	Slip Rate
Hosgri	No Change	Updated geologic rate. Pt. Estero (Cross-Hosgri slope).
Los Osos	No Change	Updated marine terrace uplift rate, new model for Irish Hills.[33];
San Luis Bay	No Change	New model for Irish Hills uplift rate.
Shoreline	No Change	Updated geologic rate, SLO Bay
All Faults	No Change	Updated regional deformation models.

Dr. Madugo reported kinematics is the sensitive movement of the faults and there was no new information for the Local Area Source Zone Model, which he described as the most important to the plant regarding the recurrence rate, activity rate, or estimated magnitudes for earthquakes based upon eight to ten years of additional data received since the last model was developed. For the Vicinity and Regional Models there were also updated earthquake catalogs and updated models developed from the USGS national seismic hazard count. He reported for all these source zones, local area, vicinity and regional, there are the USGS models which he described as largely geodetic based models which calculate on-fault deformations on the mapped faults and off-fault deformations that occur between the faults. Dr. Madugo remarked there have been calls to use the off-fault deformation as background seismicity for source zones, but he stated the data is not mature enough.

Dr. Madugo reported that external contentions were reviewed in the Updated Seismic Assessment including questions concerning the following aspects of the 2015 seismic source characterization model:

→ Use and incorporation of geodetic/kinematic models (e.g. NeoKinema);

→ Lack of inclusion of Seismic Hazard Inferred from Tectonics Model; and

→ New proponent models of fault geometry and uplift rate of the Irish Hills.

Dr. Madugo reported all the potential applications of these models were evaluated and considered in the 2023 Updated Seismic Assessment, but not as direct inputs to the logic tree and rather for comparison. He commented the review team did not believe they are applicable as direct inputs as they are more regional in extent and the Updated Seismic Assessment is a site-specific hazard study. He commented there were models that were not applicable to a site-specific hazard assessment as well as models that were not technically defensible and data or reports in previous studies that directly contradicted some of these models. He observed there were also models that were not ready yet and he cited the auxiliary fault deformation portion of the geodetic models as an example as it is unclear what signal is being recorded by this model. Dr Madugo in response to Consultant McWhorter's inquiry confirmed the evaluation of the new proponent models of fault geometry and uplift rate of the Irish Hills focused specifically on information provided by Dr. Peter Bird.

Mr. Strickland then discussed the parts of the model that were changed based on new information beginning with the Hosgri Fault slip rate characterization. He described slip rate as a estimation or proxy based on observed offset and the age of a geologic feature, that is, distance over time. He reported for the 2015 model there were four Hosgri slip rate characterizations investigated, with the northern most having been made at the San Simeon marine terraces which are offset by the Hosgri Fault. Then, further south, at Point Estero where a submerged beach berm formed about 12,000 years ago is offset by the fault, and in the Estero Bay and Point Sal submerged channels, that on the order of hundreds of thousands of years have been offset by the Hosgri Fault. The mean slip rate for the Cross-Hosgri Slope Site was 2.5 millimeters per year at the Point Estero site which over a period of 11,000 to 12,000 years is approximately 30 meters or about 100 feet. Mr. Strickland commented the Point Estero site had the highest slip rate of the four investigated, but the data were poorly constrained and the beach berm was not directly dated. He reported a study by the USGS and the University of California at Santa Barbara and others developed a stratigraphic model that supports the Point Estero feature being a submerged berm and dated it approximately the same as did the Updated Seismic Assessment. Mr. Strickland reported in the 2023 model the mean slip rate was revised from 2.5 millimeters per year to 2.6. millimeters per year.

Mr. Strickland provided the updated weights for the Hosgri Slip rate sites as follows:

Site	2015 Weight	2023 Weight
San Simeon Terraces	0.3	0.25
Cross-Hosgri Slope/Point Estero	0.2	0.50
Cross-Hosgri Slope/Point Estero	0.3	0.2
Point Sal Channel	0.2	0.05

He reported the Point Sal Channel site was downrated based upon the slip rate on the Hosgri Fault decreasing from north to south. The weighting factors were based upon location, that is, proximity to the plant and the applicability of the location, applicability of the age, uncertainty of the age and uncertainty in the offset and he commented in the modern tectonic regime the slip rates are likely representative of the current activity. He remarked uncertainties in age and in offsets were improved for the Cross-Hosgri Slope/Point Estero site which is why it was updated. In response to Dr. Lam's inquiry as to whether there has been any random analysis by using a Monte Carlo[34] simulation by assigning different weights and determining how sensitive the final results might be, Mr. Strickland replied that the process used by the Updated Seismic Assessment in assigning weights to the model was judgmental based upon criteria and he stated these criteria and the weights assigned are discussed in the report.

Dr. Kottke stated the Participatory Peer Review Panel had the same question as just posed by Dr. Lam and he remarked that the question of subjectivity is part of any SSHAC project. He commented determining the slip rate weight tells how active the fault is and that information is important as it is directly proportional to the hazard and the changes in the slip rates are supported by data. In response to Dr. Kadak's inquiry as to whether benchmarking was done to establish the weights Mr. Strickland replied they are not related directly to previous earthquakes and he observed slip rates decrease as you approach the end of the fault and the end of fault was given a lower weight and this is supported by research.

Mr. Strickland provided data on the updated Hosgri slip rate for 2015 and 2023 and the range of uncertainty shown by a curve:

Percentile	2015	2023	Change
Mean	1.70	2.14	26%
5^th	0.62	0.90	46%
50^th	1.68	2.07	23%
95^th	2.95	3.64	23%

Dr. Lam remarked seismic analysis is a complicated topic and in response to Dr. Lam's query Mr. Strickland stated that a 25% increase in the slip rate means an earthquake is more likely to happen than previously determined, but it does not mean that the earthquake will be larger. He commented that seismicity from all the primary and regional zones including the San Andreas Fault combine for the hazard. In response to Dr. Lam's comment that it would be good for members of the public to understand how the assignment of judgmental values which result in a greater value by 25% is done in order to refute certain conspiracy theories. Mr. Strickland reported all the meetings of the team assigned to make the Updated Seismic Assessment are documented and the report clearly documents all decisions made. Dr. Kottke stated the change seen is primarily a factor of the change in weight and if there was a conspiracy the sites could have been down rated, but the team relied on the most current information on age and this resulted in an increase in the slip rate.

Mr. Strickland displayed a graph showing the Hosgri slip rate cumulative distribution function on a curve that compared the 2023 Uniform California Earthquake Rupture Forecast (UCERF) regional deformation models with the different model slip rates shown as vertical bars and he remarked the cumulative distribution function captures all the different preferred rates very well, including the older version and the more recent version of NeoKinema cited by Dr. Bird. He commented all the different slip rates in the models are within the 95th percentile uncertainty developed for the site-specific study based upon the four sites. Dr. Budnitz observed the essence of the SSHAC process is to seek to capture the center, body, and range of the technically defensible interpretations and he commented one could argue that any one of the vertical lines on the graph Mr. Strickland referred to is a technically defensible interpretation. He stated that the data shown on the graph constrains the range of the Hosgri slip rate and over time more will be learned. Dr. Budnitz reported the analysts' task, having captured the center, body, and range of technically defensible interpretations, is to then find through argument and analysis some way of weighting each. He remarked the value of the graph Mr. Strickland displayed was in the use of the information to design and analyze a power plant, in that one needs to be sure there is an understanding of the origin of the variability in this one parameter which propagates its way into the design and the safety of a plant. He commented what is being shown on the curve is the analysis team's current best understanding of the state of knowledge of the Hosgri Fault slip rate. Mr. Strickland observed the distribution is an input into the hazard analysis and Dr. Budnitz observed that even at the higher slip rate, if the design of a plant's systems, structures and components can be shown to adequate, at what Dr. Budnitz described as the pessimistic end of the curve, one can have confidence the design will be adequate for the main body of the information and it is necessary to use this current state of knowledge in order to have confidence in the design.

Mr. Strickland discussed the slip rate model for the Los Osos Fault which he said is dependent upon the uplift of the Irish Hills which is determined from the data from the elevation of two key marine terraces cut around the southwest and west side of the Irish Hills which data indicates the sea level was higher when the terraces formed. Mr. Strickland reported the sea level used for the new model was almost double that used for the 2015 model and the new model was tested independently, added to the previous models, and the data weighted. He reported the result was a change in the slip rate for the Los Osos Fault by a decrease of 9% to 15 %. He reported the slip rate for the Los Osos Fault is significantly lower than that for the Hosgri Fault and accordingly the decrease does not have as much impact on the hazard as the increase of 26% in the Hosgri Fault slip rate.

In response to Dr. Lam's observation concerning the numerous inquiries from members of the public on the synergy of multiple faults Dr. Kottke reported the possibility of faults rupturing together was considered in the 2015 model and for the Updated Seismic Assessment the team reviewed the literature for any new changes in fault connection and the magnitudes assigned to joint rupture and as to how earthquakes move past structural complexities and the team found all the new information was consistent with what was included in the original model Dr. Kottke reported that this was a key component of the 2015 model and was reevaluated. Dr. Lam remarked that members of the public often question whether, given what is now known about the multiple earthquake faults, would DCPP still be built in its current location and he commented the PG&E Updated Seismic Assessment team is making a huge contribution to that inquiry and to the question of do we have reasonable assurance that the facility will perform in the design basis earthquake. Dr. Kottke replied Dr. Lam's comment speaks directly to why PG&E has a commitment to its Long Term Seismic Program to monitor new developments and he is working with research teams monitoring new developments for fault characterization and PG&E always remains active in terms of trying to understand these issues. Dr. Lam remarked that he has yet to hear as an objective of this research if, hypothetically, significant deficiencies were discovered whether a proposal for strengthening and improving any structures would be introduced. Dr. Peterson commented the higher seismic hazard was clearly recognized at the time the plant was designed and many of its features differ from plants in other areas of the country and if one looks systematically through the design of DCPP it has in every aspect been designed with a much higher level of seismic requirement which he stated is appropriate for any location in California. Dr. Peterson observed in the Committee's evaluation of DCPP the Committee has found the design has the capacity to meet the seismic loads that could occur with the higher seismic hazard at this location and that is the correct way to construct infrastructure in general, that is, to determine the local levels of hazard. Mr. Strickland agreed and he remarked looking at the history of the plant additional seismic knowledge was gained which was associated with the location and capabilities of the Hosgri Fault and the other faults and the original design for DCPP evolved to include substantial upgrades and improvements to meet the predicted hazard but also to provide long-term additional margin as more information was obtained concerning the potential hazard. Dr. Lam stated he is persuaded that DCPP complies fully with existing regulations relative to seismic safety but he remarked although the long-term seismic studies have increased design margins there are no physical improvements based on those studies and he stated his belief that there have not been any major strengthening of any vulnerable structures at DCPP. Mr. Strickland agreed and stated no such work has been undertaken at DCPP since the 1970s. Dr. Peterson observed that some time ago the amount of seismic bracing that was installed was found in some places in the plant to have made the plant too stiff and consequently to have been counterproductive and accordingly some seismic bracing has been removed.

Mr. Strickland reported that in comparing the median model to new data three additional sources were considered: (1) the West3 Project, a project conducted and funded by California Department of Transportation (CalTrans) and PG&E as well as by some other agencies to collect a new database of ground motions from three earthquakes in California which were not included in the 2015 study, but was reviewed and it was found those earthquakes were too far from DCPP to provide information; (2) data from the recent magnitude 7.8 earthquake in Turkey which he described as a large strike-slip event is being reviewed and evaluated; and (3) two magnitude 5.1 events. Mr. Strickland stated these comparisons found there was no trend between the current median model and the new data with respect to magnitude of distance and found there is no need to update the median model and the 2015 models were consistent with the new data and no changes were needed. Mr. Strickland reported one of the primary thrusts of ground motion development since the 2015 effort has been to use nonergodic[35] ground motion models. Nonergodic ground motion models are models that have spatially varying coefficients that smoothly vary across a region. He reported the 2015 effort developed models specific to DCPP and models are now being developed on a scale that varies smoothly over the state. He displayed a graph showing two nonergodic models and he commented there is very good agreement between the nonergodic models and the site specific nonergodic models previously developed. Dr. Budnitz observed different items of equipment and different structures are sensitive to different frequency period ranges on the horizontal access of the graph and Dr. Kottke confirmed the model includes modeling of the epistemic[36] uncertainty.

Dr. Kottke reported that in 2015 there were two efforts to evaluate the site characteristics, one was analytical modeling which he said was still used today, and the second was empirical modeling which relies on a limited number of recordings. He reported there have been no additional data recorded at the plant that could be used for further empirical modeling. Dr. Kottke reported non-ergodic modeling was applied to the preliminary dataset with a spatial correlation built-in to allow use of regional data to both interpolate behavior and extrapolate trends. He reported the non-ergodic site adjustment factor agreed quite well with the other models from 2015 and falls well within the bound of the empirical model that was considered. He commented at this time the approach of using non-ergodic models in this manner is preliminary and the dataset that is based from them is also preliminary, but at this point there were no changes found in terms of the site adjustment factor.

Dr. Kottke reported with the evaluation of the models there were no changes warranted in the ground motion characteristics. When the seismic source characterizations were reviewed, changes to the slip rate were identified but other aspects to the models such as the logic tree remain the same. Because changes of the source characterization are limited primarily to the slip rate he reported that those changes can be accommodated through changes in scaling of the hazard curve which eliminates the need to recompute the hazard and allows the hazard curve to be directly modified for the changes in the slip rate. Accordingly, he reported the total hazard has gone up very slightly. Dr. Kottke discussed and described the hazard curves and commented what is seen are slight differences between the uniform hazard response spectra at different return periods, but he observed they are in very good agreement. He commented the difference in contribution as a function of frequency is due to different earthquakes contributing more at different frequencies, with the Hosgri Fault being an important source for longer frequencies and as it goes up it controls more, which results in more increase at longer, lower frequencies. He reported the changes are less than the threshold of 10% which is used by NRC's Process for Ongoing Assessment of Natural Hazard Information (POANHI) and accordingly the NRC's determination would be that no change is significant. Dr. Kottke reported that instead of terminating the study at this point a risk calculation was performed. Dr. Budnitz observed what Dr. Kottke described is an increase in the annual frequency of when this rare earthquake would occur but this does not represent a change in how large that earthquake might be. Dr. Kottke agreed and he stated there is nothing learned in this effort that changes the characteristics of the event for which the plant is designed.

Mr. Strickland reported PG&E chose to review the Probabilistic Risk Assessment (PRA) Model used at DCPP which includes seismic as one of its elements and the PRA Model was updated in August 2023. He reported the update included equipment reliability data and industry peer review comments. The inputs from the revised slip rate on the Hosgri Fault were evaluated using the updated PRA Model and the results show that the amount of change in core damage frequency and large early release frequency was insignificant. The PRA Group then evaluated the change in risk compared to the overall risk criteria used by the NRC and set forth in Regulatory Guide 1.174 and found the plant continues to be essentially where most other plants are in Region 2 of that model, essentially without an impact. Dr. Peterson observed the Committee has had interest in the question of how FLEX[37] capabilities can further reduce the residual risk level associated with earthquake events which are outside the design basis and therefore events for which some action by plant staff could be helpful. He commented ensuring plant staff have the training and the resources to do that is very important and is akin to the Committee's continuing interest in workplace seismic safety. Dr. Peterson observed that the people at the plant play a critical role in a response and he commented the DCISC has a recommendation in that regard. He stated there has been work done to integrate these concepts into post-earthquake procedures but he stated it is difficult to integrate the additional risk reduction produced into a quantitative PRA as damage states can occur outside the design basis due to the unanticipated strength of the earthquake or because of a design defect. Dr. Peterson remarked DCPP has been subjected to earthquakes and is very well instrumented in terms of its structural response and has responded as expected and this improves confidence in the performance of the plant in larger earthquakes. Dr. Peterson remarked the Committee is interested in maximizing the benefits and availability of FLEX response capabilities and at some point hopefully to credit them in the overall PRA.

Mr. Strickland stated Dr. Peterson raised an interesting point and that after the accident to the Fukushima Daiichi Nuclear Power Plant in Japan, which occurred in 2011 while Mr. Strickland was still employed by PG&E, a tremendous investment in time and resources was made to not only evaluate the potential impact but to make substantial changes to the plant for secondary response capabilities and for additional resources. He reported accordingly there are significant procedures and training models developed which are now in use at the plant. Mr. Strickland stated the matter of updating the PRA to take credit was explored, but the decision was that this would be difficult to do. Dr. Peterson commented in his view one of the most effective tools to reduce the remaining residual risk of core damage and releases due to earthquakes is to think through the question of FLEX response and to be better prepared in terms of anticipating what could potentially break and accordingly the plant staff's response and it is important to confirm they have the training and equipment resources available. Dr. Peterson remarked an earthquake would lead to serious problems off-site and the same philosophy could be employed in and by the local community to evaluate other infrastructure in the region.

Mr. Strickland reported as part of the close-out process for the Updated Seismic Assessment PG&E received letters from the PPRP and from the UCLA Garrick Institute. The PPRP agreed with the conclusion that the new information for the seismic source characterization and ground motion characterization developed since 2015 has not significantly changed the estimate of the seismic risk for DCPP. He stated the Garrick Institute reached a similar conclusion and both the Garrick Institute and the PPRP provided multiple comments on the evaluation process and the technical issues covered in the draft report, all of which were considered by the Technical Integration team and the Assessment revised accordingly. Mr. Strickland reported many agencies including the DCISC were provided with draft copies of the Updated Seismic Assessment and PG&E is in the process of making the report compliant with the Americans with Disabilities Act before publicly releasing the document, which is approximately 400 pages. Dr. Budnitz observed the DCISC has a fact-finding visit scheduled for March 18, 2024, and a discussion is planned to cover some questions and issues as part of the DCISC's review.

In concluding his presentation Mr. Strickland stated the Updated Seismic Assessment found that the continued research since 2015 identified only minor changes in the source characterization of the hazard posed by significant seismic sources but no significant increase in the seismic risk. The Assessment found no new information that would change the 2015 assessment's conclusions that were reviewed and accepted by the NRC at that time and the process and results were independently verified and found to be of high quality by the PPRP and the Garrick Institute.

Dr. Budnitz asked Mr. Strickland to explain to the public the extent to which the Updated Seismic Assessment did not precisely follow the SSHAC process as set forth in NUREG 2213. Dr. Kottke reported whereas many SSHAC processes represent a wholly new effort, the Updated Seismic Assessment is a revision and accordingly was accomplished in a two-stage fashion with the first stage being a scoping evaluation stage looking at what potential changes there were in information and then determining how to take those changes and incorporate them into the hazard evaluation. He commented in a typical SSHAC process a new hazard logic tree and hazard input documentation would have been developed. He reported in undertaking the Updated Seismic Assessment PG&E was able to take an analytically correct approach to scale the hazard curves instead of recomputing the hazard. Dr. Budnitz observed that having the PPRP and the objective of capturing the center, body, and range of technically defensible interpretations were both principal features of the SSHAC process as well as of the Updated Seismic Assessment. Dr. Kottke confirmed Dr. Budnitz' observation and he remarked that the Updated Seismic Assessment, unlike a typical SSHAC process which stops at a hazard assessment, continued and followed through to a risk assessment.

In response to Dr. Kadak's inquiry Mr. Strickland replied Dr. Peter Bird's assessment of seismic conditions did not include the seismic hazard or the seismic risk. He reported Dr. Bird's assessment cited potential model inputs to be considered and all were assessed. These model inputs were not integrated directly into the models as an update to the logic tree but for some of the models comparisons were done and then they were shown with the cumulative distribution function. Some of the models suggested by Dr. Bird were found not to be appropriate and this determination was reviewed by the PPRP and the external reviewers in context of the site specific hazard assessment. He remarked some of the component models, for example the model on geometry, had been the focus of in-depth discussion during previous hazard updates and studies and as such had been evaluated. Dr. Bird mentioned slightly different geometry, but he did not provide new data or information to support his position and if in the future there is more information brought forward to support Dr. Bird's models it would be considered. He confirmed Dr. Kadak's observation that Dr. Bird's assessment was not used due to a lack of data and for the reason that it was not technically defensible. Mr. Strickland reported Dr. Bird's uplift rate for the Irish Hills, provided for purposes of previous reports, completely contradicted the Updated Seismic Assessment's model. Mr. Strickland stated Dr. Bird's model was developed using a very regional scale, almost a United States' scale data, but for the 2011 Shoreline Fault report PG&E had site-specific evaluations done which came to an opposite conclusion. Mr. Strickland confirmed that the justification for excluding Dr. Bird's data is fully set forth in Chapter 6 of the Updated Seismic Assessment.

Dr. Gene Nelson of Californians for Green Nuclear Power was recognized. Dr. Nelson offered his commendation to the members of the team who prepared the Updated Seismic Assessment for what he described as a very high quality report. He commented that during previous visits to DCPP he observed the massive scale of the steel I-beams which provide its seismic capabilities. Dr. Nelson reported the slip rates for the San Andreas Fault of 20 to 35 millimeters per year are approximately ten times those of the Hosgri Fault and he observed that with a lower slip rate the hazard is correspondingly lower. Dr. Nelson commented that each time a seismic event occurs in an area of multiple faults as the motion crosses a fault a part of its energy is attenuated over distance. He contrasted the site of DCPP with the site of the North Anna Nuclear Power Station in Virginia which he observed is built on a single block of granite. He remarked at DCPP the rock is mostly metamorphic which has been heavily faulted and therefore attenuates much faster.

Mr. Bruce Severance was recognized. Mr. Severance stated he was grateful for the thorough review provided by the PG&E representatives and he is a proponent of the peer review process. He stated he was concerned about a conversation he had with Dr. Sam Miranda and he requested that the DCISC verify the information he recalled from that conversation as Dr. Miranda, who Mr. Severance reported was formerly associated with the NRC, discussed a program called "leak before you break" and Mr. Severance stated he believes that program to be in use at DCPP. He inquired if cross members for parts of the plant's cooling system had been removed in order to detect leaks before a catastrophic break occurs and whether that action [removal of the cross members] had been evaluated for interaction with stress corrosion cracking in addition to a loss of coolant accident (LOCA) scenario which he observed could be initiated by multiple causes. Dr. Peterson replied the rationale for the "leak before you break" concept is to discover the existence of a through-wall flaw in a pipe before it proceeds to a point where it propagates a rupture and a LOCA results. Dr. Peterson observed the plant's Technical Specification requirements are to detect any leak that exceeds one gallon per minute, as it is likely that detection of such a leak would preclude it developing into a situation where a break could occur. Mr. Severance stated he understood that there are five different, redundant, systems for leak detection at DCPP and there have been occasions where more than one has been unavailable, although he stated he has been unable to discover evidence to back up this statement. Dr. Peterson reported the plant is designed with an Emergency Core Cooling System (ECCS) that is capable of coping with a leak of any size, including a double 'guillotine' break, and the "leak before you break" philosophy is to be able to detect leaks before a break can develop and thereby reduce the frequency by which large breaks would occur. Mr. Severance stated his understanding that Dr,. Miranda was concerned about the potential for leakage in excess of what the ECCS could withstand. Dr. Kadak recommended a book to Mr. Severance entitled "Nuclear Engineering Theory and Technology of Commercial Nuclear Power" by Professor Ron Knief to provide him with information on nuclear power plants.

Ms. Jill ZamEk, attending remotely, was recognized. In response to her question as to the role of the Independent Peer Review Panel (IPRP) Dr. Budnitz explained the IPRP was created by the State of California and the California Public Utilities Commission facilitates its meetings. The IPRP consists of several seismic experts who are employed by state public agencies and their purpose is to provide an independent review of the technical quality of PG&E's Seismic Safety Programs for DCPP. The IPRP meets once or twice each year and provides written reports of its reviews which concentrate upon seismicity and ground motion aspects and the IPRP has also done reviews of the seismic adequacy of buildings at the site. Dr. Budnitz reported the IPRP was not involved in the Updated Seismic Assessment and the PPRP (Participatory Peer Review Panel) is a separate and different entity from the IPRP. Dr. Budnitz stated it is his understanding the IPRP is planning to meet sometime in April or May of 2024 to discuss and provide its evaluation of PG&E's Updated Seismic Assessment.

Mr. Tim Dawson, with the California Geological Survey and a Member of the IPRP, was recognized and Mr. Dawson reported he was present representing the IPRP and other IPRP members were attending remotely. Mr. Dawson stated the IPRP just received a copy of the Updated Seismic Assessment and will be doing an independent review as required by SB846 and will provide that report when it is complete to the DCISC.

Dr. Peter Bird, attending remotely, was recognized. Dr. Bird stated he was representing the San Luis Obispo Mothers for Peace and he stated he was not surprised by the PG&E response to his input but he was very disappointed as he believes PG&E has made two fundamental errors and is justifying those errors on transparent and weak excuses. He first observed he presented arguments that there are active thrust faults at shallow depths under DCPP and the Updated Seismic Assessment failed to consider these faults because there was no new data. He commented the primary basis for his expert opinion was based on old data, on information that existed prior to 2015, including published geologic maps and sections and uplift maps produced by PG&E. To the extent PG&E failed to take this alternative expert interpretation of existing data into account Dr. Bird stated PG&E failed to follow the SSHAC process.

Dr. Bird then remarked that PG&E has asserted that the Updated Seismic Assessment was only an update and therefore it was not necessary to follow the SSHAC process and only necessary to change numbers in the existing deformation models and logic trees. Therefore, he stated the designation of a SSHAC process should be removed from the Updated Seismic Assessment and the Assessment should be termed an update of the seismic source characterization.

Dr. Bird commented the omission of the SHIFT model for converting distributed deformation rates into seismicity was very important. He remarked if the deformation model is missing thrust faults, but the GPS data shows that there is horizontal compression occurring then the SHIFT model will produce a calculated regional seismicity that largely compensates for the missing thrust faults in the deformation model. He observed the fact PG&E has decided not to use this data simply because the USGS is not using it is to Dr. Bird due to the fact PG&E has a guilty conscience about neglecting those thrust faults.

Dr. Bird stated that in 2018 PG&E filed a Seismic Probabilistic Risk Assessment (SPRA) report with the NRC that stated the seismic core damage frequency was 2.8x10^-5per year and now in the PG&E filing in November 2023 of the environmental report this number has change to 2.96 x10^-5 per year which is approximately a 6% increase. Dr. Bird said he has a question whether the new figure in the environmental report includes the findings from the Updated Seismic Assessment seismic source characterization even though the filing of the environmental report occurred three months prior to completion of the Updated Seismic Assessment. Mr. Strickland replied that the number used in the environmental report did not derive from the Updated Seismic Assessment but rather from the results of the updated SPRA model from August 2023 which he referred to in his presentation.

Dr. Madugo explained that Chapter 6 of the Updated Seismic Assessment goes into considerable detail as to why certain models were not included and as to how they were considered or found not technically defensible. Dr. Madugo, in response to Dr. Lam's prompt, explained the Updated Seismic Assessment is not a SSHAC report but borrows elements of the SSHAC process and it describes what elements were used and which are different from the SSHAC process. In terms of not including certain models such as the SHIFT model, the Technical Integration team reviewed it as did the PPRP and the Garrick Institute and at this point it was not felt it was applicable for seismic hazard evaluation for the plant and the justification for this is explained in Chapter 6.1.

Mr. John Geesman representing the Alliance for Nuclear Responsibility was recognized. Mr. Geesman stated in 2008 the California Energy Commission requested that PG&E in its AB 1632 report[38] do a deterministic evaluation of the possibility of a thrust fault directly beneath the plant and Mr. Geesman stated PG&E has never released a public response to that request. Mr. Geesman stated his belief that Dr. Bird raises an important point in that this has been left unaddressed at least in a public forum and while the Updated Seismic Assessment provided that forum, the issue remains unaddressed.

Mr. Geesman stated with respect to the SSHAC requirements he believes the NUREG document referred to by Mr. Strickland is expressly designed to address how to update an existing SSHAC report and for some time now everyone has 'danced around' how close a replication of those requirements the Updated Seismic Assessment will represent. Mr. Geesman commented that no one has explained in any detail, and Dr. Budnitz has apparently forgiven the differences, exactly what variances have taken place and exactly what justification supports those variances. Mr. Geesman remarked that although it may be unpleasant to recall, the PG&E Geosciences Department has a past history of problems with adherence to established procedures and he commented he believes these are all questions that will undermine the credibility of what may be a very worthwhile seismic update.

Mr. Geesman commented with reference to the impact of a smaller earthquake on reliability of plant equipment that Dr. Abrahamson, who is one of the members of the PPRP, in 2008 told the California Energy Commission that the primary threat to the plant comes from one of the lesser earthquakes that could cause a prolonged shut down. He recalled the experience of the Kasiwazaki-Kariwa Nuclear Power Plant in Japan which suffered just such a prolonged shut down just prior to the release by the Energy Commission's AB1632 Report. Mr. Geesman observed Mr. Jones previously highlighted as a pillar of PG&E corporate planning the issue of corporate values and Mr. Geesman believes this comment was an emphasis on equipment reliability. He commented the taxpayers are financing a forgivable loan of $1.4 billion to PG&E and one of the covenants in the loan is to perform a seismic update. He commented the premise of extended operation is to improve reliability of the electrical system and it appears, and Mr. Strickland confirmed, from the DCISC's last meeting that the Updated Seismic Assessment does not address the impacts of lesser earthquakes on equipment reliability. He stated he looks forward to receiving a copy of the final report when it is made available.

Dr. Budnitz remarked that he had not forgiven differences between the process used for the Updated Seismic Assessment and the traditional SSHAC process but he has not yet gotten to the stage of reviewing that issue and a DCISC fact finding team is scheduled to meet with PG&E representatives next month and Dr. Budnitz stated he will have several questions at that time and until then he does not have an opinion on whether or not the deviations between the literal SSHAC process and the Updated Seismic Assessment are important or not. Mr. Geesman stated he understood Dr. Budnitz' remark.

Dr. Lam stated that be believed Mr. Geesman has informed the Committee and made an allegation that information was withheld from members of the public and he asked if PG&E would like to respond. Mr. Strickland stated he was a PG&E employee when the AB1632 studies were undertaken and the DCPP AB1632 team reported to him. He commented he has no memory of any requirement in the AB1632 studies to evaluate thrust faults underneath the plant. He observed the AB1632 studies were couched in terms of better qualifying the faults in the area using a combination of low energy and high energy assessment techniques and PG&E complied with the requirements of AB1632 with the exception of a component to conduct offshore high energy seismic surveys due to the refusal of the state to issue required permits. He remarked the contention posed by Mr. Geesman that PG&E has hidden information or not shared information is incorrect and if there is a question that the Alliance for Nuclear Responsibility would like to pose to PG&E he suggested that a letter be provided to this effect and PG&E will review and provide an appropriate response. Mr. Jones stated he concurred with Mr. Strickland and invited Mr. Geesman to send such a letter.

Mr. Strickland stated that the thrust faults beneath the Irish Hills and beneath the plant have been considered in past studies and in models. The AB1632 report looked at specific proponent models for thrust faults beneath the plant and there is an entire chapter devoted to that topic. As part of the SSHAC Level III process proponents made similar contentions and there were also evaluations of the state of stress and strain beneath the Irish Hills and whether it was possible to have thrust faults or strike slip faults or a combination of the two. In the three geometry models he mentioned during his presentation the center, body and range of the differing geometries are accounted for and this included thrust faults. He reported the local area source zone which includes the plant includes virtual faults, because there is uncertainty as to whether there could be strike slip or reverse faulting, He remarked the probability is that those virtual faults are strike slip but there is a possibility they are reversed faults dipping beneath the plant. The spacing of those faults in the model is one kilometer throughout the zone surrounding the plant and therefore the model allows for and considers these types of faults beneath the plant.

Dr. Budnitz stated he listened to Dr. Bird's comments and remarked he has studied sections of the draft Updated Seismic Assessment that deal with Dr. Bird's propositions and he understands the information provided but he has some questions to pose to PG&E at the fact finding to be conducted in March 2024 and until then he will not have a final conclusion or judgment as to his agreement with Chapter 6 of the Updated Seismic Assessment.

Mr. David Weisman of the Alliance for Nuclear Responsibility was recognized. Mr. Weisman stated that there are certainly thrust faults under the Irish Hills as there have been two recent earthquakes, one about eight kilometers northwest of Avila Beach to the east of the plant, and the other five kilometers west of Baywood offshore from Los Osos. He remarked that per the 'beach ball charts' both were very clearly thrust fault mechanisms albeit small in magnitude, but representative of data points which post-date the Updated Seismic Assessment. Mr. Strickland observed the earthquakes mentioned by Mr. Weisman occurred in areas where similar small earthquakes with similar focal mechanisms, similar to thrust or reverse faults, have occurred in the past and there are various earthquakes that occur beneath the Irish Hills which is what generates the element of uncertainty. He observed PG&E has worked with USGS to develop a refined seismic catalog and has identified seismic lineaments based on that seismicity and the background model accounts for this variation in seismicity from these small earthquakes.

The Chair thanked the PG&E speakers on behalf of the Committee for an exceptionally good briefing on an exceedingly difficult scientific matter. Dr. Lam then asked Mr. Jones to introduce the final presentation by PG&E for this public meeting. Mr. Jones then introduced Senior Director of Engineering, Projects and Outages Mr. Allen Wilson. Mr. Jones reported Mr. Wilson has fourteen years of experience with PG&E and has served in various responsible roles in the Engineering, Maintenance, Decommissioning and License Renewal Departments. Prior to working for PG&E Mr. Wilson served with the United States Navy and Coast Guard and in various civilian engineering capacities.

Results of Study Required Under SB846 by Independent Consultants to Catalog and Evaluate Any Deferred Maintenance.

Mr. Wilson stated that at DCPP all necessary investments have been made and continue to be made to ensure safe and reliable operations. He remarked maintenance practices are assessed continually by the NRC and DCPP is among the highest performing plants in the nation. Mr. Wilson observed a provision of SB846 required PG&E to commission a study by independent consultants to catalog and evaluate any deferred maintenance [due to the expectation of the plant closing sooner] and to provide recommendations on the risk, the potential remedies, and the cost estimates and how soon or timely those remedies needed to be implemented. Mr. Wilson reported to meet this requirement PG&E hired two independent industry experts, Mr. Bill Dean and Mr. Ed Cowan.

Mr. Wilson reported the consultant's final Report, "Senate Bill 846 Independent Review Team Report" (Report) issued on October 31, 2023, concluded that DCPP has not experienced any deferred maintenance that would create a vulnerability to future operation and there were no remediations necessary. The Report found DCPP has been well-maintained, the plant has a strong performance record and plant staff and management are clearly focused on safe and reliable operation of the plant and since no deferred maintenance was identified there were no recommendations. Mr. Wilson reported the review team reviewed data over the previous twelve to fifteen years, from the periods prior to decommissioning, upon the decision to proceed to decommission the plant, and then when direction was provided to commence efforts to maintain continued operations with the passage of SB846. Mr. Wilson reported the review team interviewed staff and DCPP contractor personnel who support preventative maintenance work. Mr. Wilson stated the team performed walkdowns to assess the plant's general condition and reviewed various reports from the NRC and other industry experts to ensure a full picture was provided regarding maintenance. In response to Dr. Lam's inquiry Mr. Wilson replied the two consultants produced a single report which was sent to Mr. Wilson's organization for fact checking and further validation through the review of additional records. He reported Mr. Dean reviewed maintenance from a regulatory perspective and he contracted with Mr. Cowan to do the technical review.

Mr. Wilson reviewed and summarized the results of other reviews conducted of maintenance at DCPP as follows:

→ By the DCISC – August 2023 : "DCPP's process for reviewing the need for changes to Preventive Maintenance activities, Corrective Maintenance activities, and projects to support five years of extended operations (the PMO++ Program) appeared well planned and implemented."

→ NRC – 4^th Quarter of 2023: "…No maintenance plan was deferred that would impact plant safety or reliability" and the process used was reasonable and prudent.

→ STARS[39] -: "…[O]bjective was to review the Project Results for the purpose of identifying potential gaps or opportunities in consideration of Risk, Project Timing / Prioritization and Organizational Ability to Execute" that is, an industry peer review from an operating experience perspective.

→ INPO/Industry Executives: "Overall, the approach is aligned to industry practice" and reviewed from the perspective of the process for reviewing items and how DCPP was measuring compared to excellence standards.

Mr. Wilson commented these reviews support DCPP's focus on maintaining the plant to the highest standards and ensure all regulations and requirements to support extended operations are met. In response to Dr. Lam's question Mr. Wilson replied the NRC review was not done in context of the License Renewal Application but rather as part of the NRC's regular quarterly reviews and inspections with an additional inspection reviewing DCPP's processes and compliance with the NRC Maintenance Rule.[40] Mr. Wilson observed the Maintenance Rule is the NRC's guiderail for ensuring preventative maintenance and corrective actions are done properly. Mr. Wilson confirmed Dr. Lam's observation that the NRC did not review the Report.

Consultant McWhorter remarked that Mr. Wilson was asked to make this presentation because the Committee's timeframe imposed by SB846 for review of the issue of deferred maintenance required that the DCISC make its review during the first half of 2023 and throughout the summer months and to report on those efforts at the Committee's September 2023 public meeting and the independent consultant's Report was not finalized until October 2023, and therefore this represents the first opportunity to discuss the final Report in a public forum. Mr. McWhorter reported DCPP shared the preliminary results with the DCISC prior to the final Report's release and the DCISC's conclusions were based upon that knowledge and once the final Report was issued it was reviewed and a determination made that there was no effect on the Committee's conclusions as expressed at the Committee's September 2023 public meeting.

In concluding his remarks Mr. Wilson stated the Report by the independent consultants was sent to PG&E, to the DCISC and also to the State of California Department of Water Resources but at the present time it has not been made available to the general public. In response to Dr. Budnitz' request, Mr. Jones stated that he would review to ensure there was no confidential or privileged information contained in the Report and advise as to whether the Report could be made public.

Mr. John Geesman representing the Alliance for Nuclear Responsibility requested that when the Report is permitted to be made public that it be posted on the DCISC's website.

Ms. Jill ZamEk was recognized. In response to Ms. ZamEk's inquiry Mr. McWhorter and Dr. Budnitz explained that while the item on the Committee's Open Items List regarding review of deferred maintenance was closed at the conclusion of the Committee's review in 2023, there are many items on the Open Items List related to maintenance of systems and programs which remain permanently on the Open Items List for the Committee's review and the Open Items List is publicly available.

XXXI CONCLUDING REMARKS & DISCUSSION BY COMMITTEE MEMBERS OF FUTURE DCISC ACTIVITIES

There being no concluding remarks by the Members and all business of the Committee having been addressed, Dr. Lam expressed the thanks of the Committee to Mr. Blair Jones and Ms. Brandy Lopez for providing excellent technical and other assistance to the Committee and to all the persons who participated in this public meeting in person or remotely by Zoom or listened to the livestream broadcast and also to all PG&E's senior managers. Mr. Rathie expressed his appreciation to the AGP Video technicians for ensuring the virtual aspect of the meeting ran smoothly.

Mr. Rathie announced the next public meeting of the DCISC would be held on June 20-21, 2024, in Avila Beach, California, and Dr. Lam remarked this would be his final meeting as a DCISC Member as his term ends on June 30, 2024.

XXXII ADJOURNMENT OF ONE HUNDRED AND SEVENTH PUBLIC MEETING

There being no further business, the one hundred and seventh public meeting of the Diablo Canyon Independent Safety Committee was then adjourned by its Chair, Dr. Peter Lam, at 4:30 p.m.

[1] On September 2, 2022, Governor Newsom signed California Senate Bill 846, codified as Public Resources Code Sections 25233, 25233.2 and 25302.7, Public Utilities Code Sections 712.1 and 712.8, and Water Code Section 13193.5 which, together with the approval by the CPUC on December 14, 2023 of Decision 23-12-036, provides for the conditional extension of operations at Diablo Canyon beyond the current retirement date, up to five additional years, that is no later than October 31, 2029 for Unit 1 and October 31, 2030 for Unit 2, under specific conditions as provided by the legislation including approval by the NRC of extending the operating licenses for Diablo Canyon.

[2] The NRC's Regulatory Guide series provides guidance to licensees and applicants on implementing specific parts of the NRC's regulations, techniques used by the NRC staff in evaluating specific problems or postulated accidents, and data needed by the staff in its review of applications for permits or licenses.

[3] Key to some abbreviations used: Emergency Preparedness Organization (EPO); Fact-finding (FF), Diablo Canyon Independent Peer Review Panel (IPRP), Integrated Public Alert Warning System (IPAWS), Public Meeting (PM), Robert J. Budnitz (RJB), Richard D. McWhorter Jr. (RDM), Per F. Peterson (PFP), R. Ferman Wardell (RFW).

[4] Robert J. Budnitz (RJB), Andrew C. Kadak (ACK), Mark Kirk (MK), Peter Lam (PL), Richard D. McWhorter Jr. (RDM), Per F. Peterson (PFP), R. Ferman Wardell (RFW), To be Determined (TBD).

[5] It was subsequently confirmed that a confidential version of the evaluation and catalog was provided to the DCISC of the draft evaluation and catalog of maintenance activities by the independent consultant team together with the March 2024 transmittal.

[6] The Joint Proposal was entered into by PG&E, together with Friends of the Earth, the Natural Resources Defense Council, Environment California, the International Brotherhood of Electrical Works Local 1245, Coalition of California Utility Employees and the Alliance for Nuclear Responsibility in June 2016 to retire DCPP at the expiration of the current operating licenses for each unit, November 2024 for Unit-1 and August 2025 for Unit-2 and was subsequently approved by the CPUC in 2018 in Decision (D) 18-01-022. D.23-12-036 abrogated those provisions of D.18-01-022 that would have required the plant to cease operations at the end of its current operating licenses in November 2, 2024 (Unit 1) and August 26, 2025 (Unit 2).

[7] There are two categories of reactor operator licenses: a reactor operator and a senior reactor operator. A senior reactor operator supervises the reactor operators. The licenses are issued after the individual passes both a written exam and an operating test. The senior reactor operator exam measures the individual's ability to direct licensed operators.

[8] The regulatory objective of the Maintenance Rule, 10 CFR 50.65, is to require licensee monitoring of the overall continuing effectiveness of maintenance programs to ensure safety-related structures, systems, and components (SSCs) and certain SSCs that are not safety related are capable of performing their intended functions, for equipment that is not safety related, failures will not occur that prevent the fulfillment of safety-related functions, and failures resulting in unnecessary actuations of safety-related systems are minimized.

[9] The ++ designation stands for projects and life cycle review.

[10] A reactor trip is a protective function performed by the protection and safety monitoring system when it anticipates an approach of a parameter to its safety limit. Reactor shutdown occurs when electrical power is removed from the rod drive mechanism coils, allowing the rods to fall by gravity into the reactor core.

[11] See November and December 2023 Fact Finding Reports review of emergent work identifying to address a small leak on the Unit 1 pressurizer.

[12] FLEX is not an acronym but describes a strategy developed by the nuclear industry to provide diverse and flexible coping strategies to address the loss of safety-related systems due to certain beyond design basis events. It is a group of supplemental components, many of them portable, which are seismically stored, and can be made available for timely attachment to permanent plant systems for accident mitigation.

[13] As part of an NRC license authorizing operation of a nuclear facility, Technical Specifications establish requirements for items such as safety limits, limiting safety system settings, limiting control settings, limiting conditions for operation, surveillance requirements, design features, and administrative controls.

[14] A probabilistic risk assessment of Green means there is no equipment out of service or some other compromise to safety that would make the relative risk higher than the probabilistic risk assessment baseline for normal operation and maintenance activity and accordingly trigger a classification, in descending order, of White, Yellow or Red.

[15] The Simulator Facility is a full-size mockup of the Unit 1 Control Room.

[16] In order to review the state-of-the-art and improve on the overall stability of the Probabilistic Seismic Hazard Assessment (PHSA) process, the NRC, the U.S. Department of Energy (DOE), and the Electric Power Research Institute (EPRI) co-sponsored a project to provide methodological guidance on how to perform a probabilistic seismic hazard assessment (PHSA). The project was carried out by a seven-member Senior Seismic Hazard Analysis Committee (SSHAC) Chaired by Dr. Robert J. Budnitz and supported by a large number of other experts.

[17] Surveillance specimen capsules must be located near the inside vessel wall in the beltline region so that the specimen irradiation history duplicates, to the extent practicable within the physical constraints of the system, the neutron spectrum, temperature history, and maximum neutron fluence experienced by the reactor vessel inner surface.

[18] DCPP's two pressurized water reactors were manufactured by the Westinghouse firm.

[19] The NRC provides guidance to licensees and applicants by issuing NUREG-series publications regarding regulatory decisions, research results, results of incident investigations, and other technical and administrative information. NUREG-series publications disseminate scientific, technical, and administrative information dealing with licensing and regulation of civilian nuclear facilities and materials. Publications in the NUREG series may neither state nor imply any regulatory requirements, since such requirements are stated only in laws, regulations, licenses (including technical specifications), or orders. In other words, the NRC staff may suggest a course of action in a NUREG-series publication, but the regulated community may use other approaches to satisfy the agency's regulatory requirements.

[20] In materials science, the Charpy impact test, also known as the Charpy V-notch test, is a standardized high strain rate test which determines the amount of energy absorbed by a material during fracture. Absorbed energy is a measure of the material's notch toughness.

[21] A joule is a unit of energy in the International System of Units. It is equal to the amount of work done when a force of one newton displaces a mass through a distance of one meter in the direction of that force. It is also the energy dissipated as heat when an electric current of one ampere passes through a resistance of one ohm for one second.

[22] In many fields, it's common for Δ (the Greek letter delta) to represent a change or difference. Math uses it, physics uses it, engineering uses it, etc.

[23] Mathematically, interpolation is the process of determining an unknown value within a sequence based on other points in that set, while extrapolation is the process of determining an unknown value outside of a set based on the existing "curve."

[24] A J-R curve, is a useful tool for evaluating a material's structural integrity in the presence of preexisting defects. The J-R curve can calculate the work (energy) per unit of fracture surface area needed to drive crack growth.

[25] Micro-CT is a 3D imaging technique utilizing X-rays to see inside an object, slice by slice. Micro-CT, also called microtomography or micro computed tomography, is similar to hospital CT or "CAT" scan imaging but on a small scale with greatly increased resolution. Samples can be imaged with pixel sizes as small as 100 nanometers and objects can be scanned as large as 200 millimeters in diameter.

[26] CV curves are curves controlled by control vertices (CVs). The CVs don't lie on the curve. They define a control lattice that encloses the curve. Each CV has a weight that you can adjust to change the curve.

[27] The Price-Anderson Act (PAA) provides a system of financial protection for persons who may be liable and persons who may be injured by a nuclear incident.

[28] A probabilistic risk assessment of Green means there is no equipment out of service or some other compromise to safety that would make the relative risk higher than the probabilistic risk assessment baseline for normal operation and maintenance activity and accordingly trigger a classification, in descending order, of White, Yellow or Red.

[29] Primary and secondary side refer, respectively, to the Reactor Coolant System which is used to remove heat from the nuclear reactor and to the Main Steam and Feedwater Systems which provide cooling to the steam generators and generate and provide steam to the turbines.

[30] There are six Westinghouse PWR operation Modes: Mode 1 - power operation, Mode 2 - startup, Mode 3 - hot standby, Mode 4 - hot shutdown, Mode 5 - cold shutdown, and Mode 6 - refueling.

[31] Source term refers to the types, quantities, and chemical forms of the radionuclides that encompass the source of potential for exposure to radioactivity.

[32] The safety significance characterizations used for the Performance Indicators as either Green (very low), White (low to moderate) Yellow (substantial) or Red (high). A Green non-cited violation indicates very low safety significance, with no impact to public health and safety.

[33] The Irish Hills embrace the rugged, western portion of the San Luis Range, extending from the Pacific Ocean to Los Osos Valley, and from the town of Los Osos on the north to the San Luis Obispo Creek on the south. The largely undisturbed and highly scenic site includes PG&E properties surrounding the DCPP.

[34] A Monte Carlo simulation is a model used to predict the probability of a variety of outcomes when the potential for random variables is present. Monte Carlo simulations help to explain the impact of risk and uncertainty in prediction and forecasting models. A Monte Carlo simulation requires assigning multiple values to an uncertain variable to achieve multiple results and then averaging the results to obtain an estimate.

[35] Ergodic relates to a process in which every sequence or sizable sample is equally representative of the whole (as in regard to a statistical parameter).

[36] Epistemic means of or relating to knowledge or the conditions for acquiring it.

[37] FLEX is not an acronym but describes a strategy developed by the nuclear industry to provide diverse and flexible coping strategies to address the loss of safety-related systems due to certain beyond design basis events. It is a group of supplemental components, many of them portable, which are seismically stored, and can be made available for timely attachment to permanent plant systems for accident mitigation.

[38] The purpose of the report required by California Assembly Bill (AB) 1632 and prepared by the California Energy Commission was to assess the potential vulnerability of California's largest baseload power plants, Diablo Canyon Power Plant and San Onofre Nuclear Generating Station, to a major disruption due to a seismic event or plant aging; to assess the impacts of such a disruption on system reliability, public safety, and the economy; to assess the costs and impacts from nuclear waste accumulating at these plants; and to evaluate other major issues related to the future role of these plants in the state's energy portfolio.

[39] Strategic Teaming and Resource Sharing (STARS) joint utility cooperative consisting of Union Electric Company, with its Callaway plant in Missouri; Arizona Public Service Company, with its Palo Verde plant in Arizona; Luminant Generation Company LLC, with its Comanche Peak plant in Texas; Pacific Gas and Electric Company, with its Diablo Canyon plant in California; Southern California Edison Company, with its San Onofre plant in California; STP Nuclear Operating Company, with its STP plant in Texas; and Wolf Creek Nuclear Operating Company, with its Wolf Creek plant in Kansas.

[40] The NRC Maintenance Rule requires plant owners to develop programs that periodically evaluate the effectiveness of their existing maintenance activities to help assure that safety equipment remains able to perform safety functions.

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