ML25142A372

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Meeting Summary for Waterford 3 - Pre-Decisional Regulatory Conference with Entergy Operations, Inc., Waterford Steam Electric Station, Unit 3
ML25142A372
Person / Time
Site: Waterford Entergy icon.png
Issue date: 05/21/2025
From:
NRC/RGN-IV/DORS/PBD
To:
References
EAF-RIV-2025-0090
Download: ML25142A372 (1)
v • d • e


Text

NRC REGULATORY CONFERENCE

SUMMARY

Licensee: Entergy Operations, Inc.

Facility: Waterford Steam Electric Station, Unit 3 License No. NPF-38 Docket No. 05000382 Date of Conference: May 21, 2025 EAF-RIV-2025-0090 NRC REGULATORY CONFERENCE

SUMMARY

On May 21, 2025, representatives of Entergy Operations, Inc. and Waterford Steam Electric Station, Unit 3, met with U.S. Nuclear Regulatory Commission (NRC) personnel to discuss the apparent violation identified in NRC Inspection Report Number 05000382/2025090, dated March 20, 2025 (NRC's Agencywide Documents Access and Management System [ADAMS]

Accession No. ML25097A205). The regulatory conference was held at the request of the licensee and was characterized as an NRC public meeting. The meeting was held in the NRC Region IV office via Microsoft Teams Meeting and with an associated bridge line for audio. The list of attendees is provided as an enclosure to this summary (Enclosure 3).

The NRC representatives discussed the preliminary White finding that was described in the subject inspection report and provided an overview of NRCs Reactor Oversight Process (ROP) for significance determination, as shown in the NRC presentation (Enclosure 1). During the opening of the meeting, NRC staff also clarified any changes to the NRC agenda from what was published in the public meeting notice on May 7, 2025, and provided the conference logistics.

The licensees staff leading the presentation included the Site Vice President, Engineering Director, Regulatory Assurance Manager, and Risk Engineering Manager. They were also supported by an engineering consultant and a principal from Socotec Engineering. These individuals provided their response to the preliminary White finding, as shown in their enclosed presentation (Enclosure 2). The participants stated that Entergy Operations, Inc.

acknowledged a finding and violation for the failure to properly develop and implement adequate maintenance instructions for the fuel linkage connection to the mechanical governor for emergency diesel generator A was a performance deficiency. Specifically, the maintenance instructions for the governor replacement and the rod bearing replacement did not include adequate instructions for the installation of all required parts to ensure that mechanical binding did not occur. Overall, they asserted that the finding for an apparent White violation of 10 CFR 50, Appendix B, Criterion V was no greater than Green, a finding of very low safety significance per NRCs ROP, based on the data presented that demonstrated that the emergency diesel generator A was inoperable for only 3.53 days.

During the business portion of the meeting, NRC staff informed Entergy Operations, Inc. that the primary objectives of the regulatory conference were to obtain information to support evaluation of the findings through the Significance Determination Process (SDP) and gain their perspective on the apparent violations. NRC staff also maintained that no final decisions will be made during the meeting. All information presented during the meeting, and prior to the meeting, will be considered and assessed to make a final decision and that determination will be communicated to the licensee as soon as possible. NRC also informed the licensee that they had appeal rights if they did not agree with any final NRC determinations.

At the close of the business portion of the meeting, members of the public were allowed to ask any relevant questions and interact with NRC participants. There was no question from the public or the other NRC conference participants on the Teams Meeting or bridge line. NRC then thanked all participants and adjourned the meeting.

In accordance with 10 CFR 2.390 of the NRCs Agency Rules of Practice and Procedure, a copy of this conference summary and enclosures (Enclosure 1, 2, and 3) will be made available electronically for public inspection in the NRC Public Document room or in the NRCs Agency-wide Documents Access and Management System, accessible from the NRC Web site at http://www.nrc.gov/reading-rm/adams.html.

Enclosures:

1.

NRC Presentation-Public 2.

Licensee Presentation - Public 3.

Attendance List - Public

NRC REGULATORY CONFERENCE

SUMMARY

, Entergy Operations, Inc. and Waterford Steam Electric Station, Unit 3, May 21, 2025 DISTRIBUTION:

RidsOeMailCenter Resource RidsNrrMailCenter Resource RidsOgcMailCenter Resource RidsSecyMailCenter Resource RidsOcaMailCenter Resource RidsOigMailCenter Resource RidsEdoMailCenter Resource EDO_Managers RidsNsirMailCenter Resource RidsOiMailCenter Resource RidsRgn1MailCenter Resource RidsRgn2MailCenter Resource RidsRgn3MailCenter Resource RidsOcfoMailCenter Resource RidsOpaMail Resource JMonninger, RA RAlexander, ORA R4Enforcement BAlferink, ORA R4-DORS-IPAT GMiller, DORS ARoberts, ORA DPelton, OE NTaylor, DORS DCylkowski, ORA TSteadham, RIV/OEDO JCai, OE JDixon, DORS JPeralta, OE ASanchez, DORS AMoreno, OCA DJones, OE KChambliss, DORS LWilkins, OCA EBrothman, NRR VDricks, ORA CYoung, DORS MKhanna, NRR TSmith, ORA SHamilton, DORS RFelts, NRR LReyna, DORS NArmstrong, DORS JDrake, NRR KCook-Smith, DORS CJewett, ORA

Nuclear Regulatory Commission Regulatory Conference Entergy Operations, Inc.

Waterford Steam Electric Station, Unit 3 USNRC Region IV Wednesday, May 21, 2025 EAF-25-0090

Meeting Logistics

  • Operation of Microsoft Teams Meeting call
  • Ensure all phones and background noises are MUTED
  • Scheduled break (15-minute)
  • NRC caucus (Teams Meeting)
  • Public Question Session (if you called in, please Press *5 on phone to raise hand, then wait for the Moderator to acknowledge you. Press *6 to UNMUTE, and *5 to lower hand.)

To call in to hear this Teams Meeting presentation by phone, dial 1-301-576-2978 and enter participant code 542 542 620#.

2

Agenda Topic Participants NRC Opening Remarks and Introductions John Monninger, RIV Licensee Opening Remarks and Introductions Entergy Operations, Inc. / Waterford Steam Electric Station, Unit 3 (WAT)

Regulatory Conference Process Geoffrey Miller, RIV Possible Outcomes and Licensee Appeal Rights Geoffrey Miller, RIV Background and Summary of the Preliminary White Violation John Dixon, RIV NRCs Dispositioning Process via the Mitigating Systems (MS) Cornerstone Cale Young, RIV Summary of Violation and Cross-Cutting Aspect John Dixon, RIV Licensee Presentation Entergy Operations, Inc. / WAT Questions and Discussion NRC and WAT Participants Break and NRC Caucus NRC and WAT Participants Questions and Discussion NRC and WAT Participants Licensee Closing Remarks Entergy Operations, Inc. / WAT NRC Closing Remarks John Monninger, RIV Public Question and Answer Public Attendees MEETING AGENDA*

To call in to hear this Teams Meeting presentation by phone, dial 1-301-576-2978 and enter participant code 542 542 620#.

  • Please note this agenda has slightly changed from the Public Meeting Notice, issued 5/7/25.

3

NRC Principal Participants John Monninger Regional Administrator Geoffrey Miller DORS Director Cale Young DORS SRA Chris Jewett ACES Specialist To call in to hear this Teams Meeting presentation by phone, dial 1-301-576-2978 and enter participant code 542 542 620#.

John Dixon DORS PBD Branch Chief 4

Entergy Operations, Inc. / WAT Opening Remarks / Introductions Joe Sullivan Site Vice President, WAT Barry Davis Engineering Director, WAT Stephanie Pyle Director Fleet Reg.

John Crews Fmr. Mgr. Plant Support Kerry Gaston Manager, Risk Eng.

John Twarog Reg. Assurance Manager, WAT To call in to hear this Teams Meeting presentation by phone, dial 1-301-576-2978 and enter participant code 542 542 620#.

5

Purpose of this Regulatory Conference

  • The NRC normally provides an opportunity for a licensee to address apparent violations before the NRC takes escalated enforcement action or makes a final decision on the significance.
  • The significance assessment determines whether an escalated enforcement action will be considered (i.e., a Notice of Violation associated with a White, Yellow, or Red SDP finding). Licensee input during this conference is also considered in making a final NRC decision.

To call in to hear this Teams Meeting presentation by phone, dial 1-301-576-2978 and enter participant code 542 542 620#.

6

Todays Meeting

  • No Final Decision on safety significance or enforcement action will be made today.
  • Our NRC Inspection Report (05000382/2025090) provided our current understanding and perspective on the issue.
  • We want your, the licensees, perspective
  • Any additional details NRC should consider
  • Whether finding/violation occurred
  • Perceived significance of the finding/ violation
  • Corrective actions implemented and/or planned To call in to hear this Teams Meeting presentation by phone, dial 1-301-576-2978 and enter participant code 542 542 620#.

7

Public Meeting Disclaimer The public is invited to observe the meeting and will have one or more opportunities to communicate with the NRC after the business portion, but before the meeting is adjourned.

To call in to hear this Teams Meeting presentation by phone, dial 1-301-576-2978 and enter participant code 542 542 620#.

8

Possible Outcomes

  • The NRC determines there is no violation resulting in no enforcement action. Finding may still be possible.
  • The NRC determines the apparent violation is of very low safety significance resulting in non-escalated enforcement (Green Non-Cited Violation).
  • The NRC determines the apparent violation is of low to moderate safety significance resulting in escalated enforcement (a White Finding and an associated Notice of Violation).

To call in to hear this Teams Meeting presentation by phone, dial 1-301-576-2978 and enter participant code 542 542 620#.

9

Licensee's Appeal Rights A licensee has the right to challenge any NRC determination or action that may be presented.

Instructions for challenging an NRC enforcement action are included in our transmittal letter and the action itself.

To call in to hear this Teams Meeting presentation by phone, dial 1-301-576-2978 and enter participant code 542 542 620#.

10

Discussion of Apparent White Violation of 10 CFR 50, Appendix B, Criterion V NRC issued Choice Letter on April 9, 2025 (ML25097A205, EAF-RIV-2025-0090)

Performance Deficiency The failure to properly develop and implement adequate maintenance instructions for the fuel linkage connection to the mechanical governor for emergency diesel generator A was a performance deficiency. Specifically, the maintenance instructions for the governor replacement and the rod bearing replacement did not include adequate instructions for the installation of all required parts to ensure that mechanical binding did not occur.

To call in to hear this Teams Meeting presentation by phone, dial 1-301-576-2978 and enter participant code 542 542 620#.

11

Background Information On October 7, 2024, while performing a 24-hour surveillance test on emergency diesel generator A, an operator secured the diesel due to irregular reactive megavolt ampere reactive (MVAR) oscillations.

On October 9, after troubleshooting and repairing the issue, the licensee began a post-maintenance test run of the diesel when it tripped due to a reverse power relay signal. The licensee postulated the probable cause was a sensitive relay that tripped due to installed monitoring equipment that was connected to the same relay. The licensee removed the monitoring equipment and recalibrated the relay.

On October 10, the licensee began a subsequent post maintenance test and the diesel immediately tripped on a mechanical overspeed trip.

The licensee discovered the cause of this trip was one of the rod end linkages between the governor and the fuel oil linkage was disconnected. Further review of the reverse power trip determined the linkage became disconnected during the run on October 9.

On October 10, the fuel oil linkage to the governor was reconnected and torqued using the vendor technical document, and a post maintenance test of the diesel was completed satisfactorily, and emergency diesel generator A was declared operable.

To call in to hear this Teams Meeting presentation by phone, dial 1-301-576-2978 and enter participant code 542 542 620#.

12

Moving forward to February 2025 On February 4, 2025, the licensee inspected the same joint and found it had been incorrectly assembled.

The washer was placed underneath the bolt in lieu of its vendor specified position in between the linkage and the governor pivot arm as a spacer.

The licensee determined the washer was correctly placed in 2015, and subsequent work done between 2016 and 2018 incorrectly relocated the washer. As a result of this incorrectly placed washer, the rod end was mechanically binding with the governor pivot arm and causing the corner of the governor pivot arm to deform.

The licensee concluded the failure mechanism of this linkage was the misalignment of the rod end causing interference between the rod end and the governor pivot arm. Starting of the diesel in this condition resulted in these two components interfering with each other, therefore loosening the torqued linkage connection.

Vibration of the diesel then further loosened the connection until the fastener completely backed out of the governor pivot arm.

During this period, emergency diesel generator B also underwent similar maintenance. During these activities, the configuration control was maintained. As part of the extent of condition of the October 10, 2024, event, the linkage was torque checked and no looseness was noted at that time.

It was also determined that skill of craft activities such as free range of motion checks following maintenance and system walkdowns as required by licensee procedures could have identified the issue.

To call in to hear this Teams Meeting presentation by phone, dial 1-301-576-2978 and enter participant code 542 542 620#.

13

Dispositioning the Issue via the Mitigating Systems SDP: MTM and White Significance The inspectors assessed the significance of the finding using IMC 0609 Appendix A, The Significance Determination Process (SDP) for Findings At-Power. The inspectors determined the finding adversely impacted the Mitigating Systems cornerstone and used Exhibit 2 to evaluate the condition.

The inspectors determined the finding represented a loss of PRA function of one train of a multi-train technical specification system for greater than its allowed outage time. Therefore, a detailed risk evaluation was performed by a regional senior reactor analyst.

The senior reactor analysts significant assumptions included: 94-day exposure time, recovery of the diesel within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> of this failure should not be credited, and use of Diverse and Flexible Coping (FLEX) strategies should be credited.

Based on the results of this evaluation, the finding was determined to have a preliminary significance of low-to-moderate safety significance (White).

To call in to hear this Teams Meeting presentation by phone, dial 1-301-576-2978 and enter participant code 542 542 620#.

14

Apparent Violation of 10 CFR 50, Appendix B, Criterion V Title 10 CFR Part 50, Appendix B, Criterion V, Instructions, Procedures, and Drawings, requires, in part, that activities affecting quality shall be prescribed by documented instructions, procedures, or drawings, of a type appropriate to the circumstances and that the instructions, procedures, or drawings shall include appropriate quantitative or qualitative acceptance criteria for determining that important activities have been satisfactorily accomplished. The licensee established work orders WO-00434438 (replacement of the rod ends), WO-00482368 (first replacement of emergency diesel generator A governor), WO-00579374 (second replacement of emergency diesel generator A governor), and WO-54199975 (reassembly of the rod end linkage after it was found disconnected), in part, to meet this requirement.

To call in to hear this Teams Meeting presentation by phone, dial 1-301-576-2978 and enter participant code 542 542 620#.

15

Apparent Violation of 10 CFR 50, Appendix B, Criterion V Contrary to the above, from June 2016 to February 4, 2025, the licensee failed to adequately develop and implement instructions, procedures, or drawings for an activity affecting quality of a type appropriate to the circumstances, and to include appropriate quantitative or qualitative acceptance criteria for determining that important activities have been satisfactorily accomplished. Specifically, the licensees work orders for the replacement of the rod ends, replacement of the governor, and reconnecting of the rod end joint for emergency diesel generator A failed to include adequate maintenance and post-maintenance inspection instructions. The instructions did not include appropriate quantitative or qualitative acceptance criteria for the installation of all required parts, to include tightness checks of adjacent connections and linkages and post-maintenance inspections to ensure that mechanical binding did not occur. This resulted in the failure of emergency diesel generator A to run.

To call in to hear this Teams Meeting presentation by phone, dial 1-301-576-2978 and enter participant code 542 542 620#.

16

Cross-Cutting Aspect via IMC 0310 Using NRC Inspection Manual Chapter (IMC) 0310, Aspects within the Cross-Cutting Areas, NRC inspectors determined H.12 was most appropriate for this finding.

H.12 - Avoid Complacency:

Specifically, the licensee did not recognize the incorrect washer placement when conducting maintenance activities, nor did they recognize that the work being done could impact adjacent connections, and as such the procedures to perform maintenance were inadequate to ensure that the connection was correctly assembled. This led to damage of the mechanical governors pivot arm and inoperability of the diesel.

To call in to hear this Teams Meeting presentation by phone, dial 1-301-576-2978 and enter participant code 542 542 620#.

17

Any questions from the licensee to the NRC To call in to hear this Teams Meeting presentation by phone, dial 1-301-576-2978 and enter participant code 542 542 620#.

18

Entergy Operations, Inc. / Waterford Presentation To call in to hear this Teams Meeting presentation by phone, dial 1-301-576-2978 and enter participant code 542 542 620#.

19

NRC and Entergy Operations, Inc./Waterford Staff Q&A Session To call in to hear this Teams Meeting presentation by phone, dial 1-301-576-2978 and enter participant code 542 542 620#.

20

NRC Regulatory Conference with Entergy Operations, Inc.

Waterford Steam Electric Station, Unit 3 NRC Caucus in Session Returning Shortly To call in to hear this Teams Meeting presentation by phone, dial 1-301-576-2978 and enter participant code 542 542 620#.

21

Regulatory Conference Closing Remarks

  • Entergy Operations, Inc. / Waterfords Closing Remarks
  • NRCs Closing Remarks and Next Steps / Expectations
  • Conclusion of the business portion of todays Regulatory Conference To call in to hear this Teams Meeting presentation by phone, dial 1-301-576-2978 and enter participant code 542 542 620#.

22

Are there any questions from the public attendees?

(Please press *5 on your phone to raise your hand, then await the Moderator, *6 to UNMUTE)

To call in to hear this Teams Meeting presentation by phone, dial 1-301-576-2978 and enter participant code 542 542 620#.

23

24

Waterford Steam Electric Station, Unit 3 Emergency Diesel Generator Linkage Regulatory Conference May 21, 2025

Agenda John Twarog - Regulatory Assurance Manager 01

3 Agenda Section Presenter Management Introduction Joe Sullivan Root and Contributing Causes/

Corrective Actions John Twarog Event Overview Barry Davis Failure Mechanism Perspective John Crews/Sontra Yim Risk Insights Kerry Gaston Enforcement Perspective John Twarog Closing Remarks Joe Sullivan

Management Introduction 02 Joe Sullivan, Site Vice President

Root and Contributing Cause, and Corrective Actions 03 John Twarog - Regulatory Assurance Manager

6 Root Cause Insufficient Details Included in the Preventative Maintenance Job Plan Contrary to EN-MA-106, Planning," details needed to perform work on a critical component were not included in the Preventative Maintenance Job Plan.

Not including guidance to perform freedom of movement checks Not including guidance from vendor technical documents Missing torque values

7 Contributing Cause Contributing Cause Planning organizations adherence to standards for important work activities like EDG governor replacement did not ensure workers were in rule-based performance. This organizational performance gap represents a missed opportunity for the maintenance organization to raise standards and improve performance in Planning.

8 Corrective Actions Corrective Action to Preclude Repetition (CAPR)

Develop a Mechanical Maintenance Safety-Related Procedure for replacement of the mechanical Governor for Emergency Diesel Generators incorporating vendor documents and standards.

Issue Overview 04 Barry Davis, Engineering Director

10 Key Discussion Points

  • The laboratory testing correctly models EDG-A linkage operation and demonstrates how the linkage became disconnected
  • SOCOTEC developed the testing methodology
  • The EDG-A linkage cap screw lost preload on October 7 during shutdown
  • EDG-A ran twice in September for a total of 12.25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br />
  • EDG-A ran for 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> on October 7
  • The exposure window was 3.53 days

11 Issue Overview

  • Cooper Bessemer engine/ Woodward governor operation/linkage configuration
  • Heim joint design and purpose 11

12 EDG-A governor replaced/upgraded 10-year PM strategy established Heim joint was

replaced, necessitating replacement of the cap screw and washers EDG-A governor was replaced to fix an oil leak EDG-A electrical governor gasket was replaced 2017 Timeline 2014 2016 2018

13 EDG-A governor replaced IAW 10-year PM strategy 1/6/2024 10/7/2024 EDG-A was removed from service due to MVAR oscillations when connected to the grid during 24hr run Pre-load was lost during shutdown of emergency diesel generator Troubleshooting determined Motor Operated Potentiometer (MOP) needed to be addressed 10/8/2024 10/9/2024 Troubleshooting run of EDG-A, a reverse power trip occurred approximately 2.79 hours9.143519e-4 days <br />0.0219 hours <br />1.306217e-4 weeks <br />3.00595e-5 months <br /> into the test EDG-A immediately tripped on overspeed during start.

Cap screw on the linkage was found to have backed out 10/10/2024 10/10/2024 EDG-A PMT complete at 1705 Timeline JAN OCT 9/3/2024 EDG-A monthly surveillance 9/26/2024 EDG-A operability run after maintenance Total of 12.25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br />

Failure Mechanism Perspective 05 John Crews - Former Plant Support Engineering Manager Sontra Yim - Principal: SOCOTEC Engineering Inc.

15 Purpose of Investigation Determine cause and timing of governor linkage disconnection

  • Misalignment of governor linkage allowed mechanical interference between components
  • The interference inflicted force to loosen the mechanical linkage
  • Loss of preload occurs only in certain configurations
  • After total loss of preload, cap screw unthreading occurs rapidly

16 Event Timeline Summary 10/7/24: Reactive load fluctuations during 24-hour surveillance 10/9/24: EDG-A trip on reverse power during troubleshooting 10/10/24 (0236): Mechanical overspeed trip at startup 10/10/24 (0700): Governor linkage found disconnected

17 Linkage Assembly Overview Components: 1/2"- Cap screw, Washer, Heim joint, Lever arm, Washer

18 Key Field Observations Fretting wear observed on lever arm corner (yellow arrow) and Heim joint chamfer, indicating mechanical interference had occurred

  • Single washer installed outboard of Heim joint (blue arrow)

Slight outboard position of lever on spline shaft (red arrow)

19 Key Field Observations Contributions to interference in Position 1 (min fuel) to Position 3 Lack of washer on lever side of Heim joint Slight outboard position of lever on spline shaft 1.5° linkage misalignment relative to design axis Elevation View Plan View

20 Vibration Data and Analysis Vibration data collected via accelerometers and RDI Motion Amplification Dominant frequencies: 40 Hz and 50 Hz SRSS Heim joint displacement from dominant frequencies:

~11.4 mils pk-pk average across all load conditions

~16.4 mils pk-pk max @ 4.2 MW load Video #1

21 Fretting Vibration - Overview This test evaluated the effect of engine vibration on the retention of cap screw preload across various governor linkage positions The Heim joint was conservatively driven at 10 Hza measured harmonic of the EDGdue to limitations of the Instron testing machine Appreciable preload loss was only observed at the min-fuel position 1 Initial torque determined resistance to loss of preload Minimum Fuel Position Maximum Fuel Position

22 Test 1 - Loss of Preload in Min-Fuel Position 15 ft-lbs Initial Torque Fretting Vibration - Example Test #1 10.8 mil pk-pk

@ 10 Hz 15 ft-lbs torque = ~2000 lbs initial preload Video #2

Sweep Test

  • This test assessed the effect of the lever arm dynamically sweeping out of the minimum fuel position, towards the maximum fuel position
  • The linkage was actuated at different rates to simulate governor response during load changes
  • Progressive preload loss was observed for relatively quick (~1 second) swings from min-fuel to max-fuel
  • Slower swings (30 seconds) did not induce significant preload loss Sweep Test Setup Initial State, Minimum Fuel Position 23

Rapid (1 Second) Sweep Tests:

Loss of Preload Rapid Swing Test #10 (of 10) 0.5x Speed Total loss of preload is shown by rotation of the cap screw.

Total preload loss was observed as a sequence over the course of 10 sweep events.

Sweep Test - Rapid (~1 Second) 24 Video #3

Slow (30 Second) Sweep Tests:

Preload Maintained Slow Swing Test #5 (of 5), 1x Speed No visible rotation of the cap screw.

Sweep Test - Slow (~30 Seconds) 25 Video #4

Exaggerated Asymmetric Loading Diagram of Cap Screw Preload Loss Mechanism - Discussion 26

  • The setup reflects the running diesel configuration after the loss of preload:

Cap screw installed finger-tight, equivalent to zero preload Fixture plate holds lever arm at Position 5 (no corner interference) with 1.5 degree offset angle to joint

  • Heim joint was driven to achieve measured displacement @ 40Hz (dominant engine frequency) at Heim joint end
  • Note that this test applied uniaxial vibration and was therefore conservative; the true engine vibrations were multiaxial and would be even more effective at loosening the cap screw kV A

kV Instron Head Lever in Position 5 Fixture Plate Heim Joint Cap Screw Back-Out Testing 27

16.8 mil pk-pk

@ 40 Hz 14.6 mil pk-pk

@ 40 Hz Test #1 - 42 Minutes to Back Out (40x Speed Timelapse) 28 Video #5

15.3 mil pk-pk

@ 40 Hz 11.3 mil pk-pk

@ 40 Hz Test #2 - 10 Minutes to Back Out (10x Speed Timelapse) 29 Video #6

30 Conclusion and Cause Summary January 2024 Misalignment during assembly allowed for interference between lever arm edge and chamfer of Heim joint January - October 2024 Interference occurs at lever-to-Heim chamfer contact during min-fuel position. Asymmetric loading intensified during counterclockwise motion (loosening direction)

October 7 Most impactful forces occurring during rapid movement of lever in diesel shutdown sequence Loss of preload occurs resulting in EDG-A being unable to fulfill its safety function October 9 Post-preload loss, operational vibration drives rapid cap screw loosening. Disconnection occurs within hours, confirmed by mock-up testing

Risk Insights Kerry Gaston - Fleet Risk Engineering Manager 06

32 Exposure Time Exposure Time based on additional failure analysis Known inception time occurs when preload is lost with unloading of the EDG-A on 10/7/24 at 0424 EDG-A PMT complete on 10/10/24 at 1705 Total Exposure time of 3.53 Days

33 WF3 PRA Model Characteristics WF3 uses RG 1.200 PRA Model for FPIE, Flood, & Fire Hazards Approved for 10 CFR 50.69 (ML22300A208)

Approved for RMTS (ML22322A109)

Approved for RICT (ML22322A109)

No Open Peer Review Findings RASP Handbook Methodology Used to Evaluate Risk Associated with EDG-A Failure

34 PRA Assumptions Failure of EDG-A to Run is the initiating event (basic event EG-DGN-FR-0001-A was set to True)

Common Cause failure event alpha factor for EDG failure to run probability set to 1.38E-02 Other basic events related to EDG-A such as failure to start, failure to load and maintenance unavailability were all set to False Plant Availability Factor of 0.884 utilized The WF3 Permanent Temporary Emergency Diesel Generator (PTED) is fully integrated as a credited power source for divisions A and B in the event of a loss of offsite power

35 Defense in Depth &

Beyond Design Basis Strategies

  • 1 permanently installed temporary diesel able to supply power to either A or B divisions
  • Only Flex pre-staged (Flex N) equipment credited in the PRA model
  • 1hr ELAP declaration
  • 2hr load shed of DC buses

36 PRA Results and Conclusion Utilizing the appropriate exposure time of 3.53 days, combined internal events, fire, and flood risk analysis results conclude Delta CDF calculated3.39E-07 Delta LERF calculated: 9.93E-10

Enforcement Perspective John Twarog - Regulatory Assurance Manager 07

38 Multiple layers of defense-in-depth remained in place

  • Permanent Temporary Diesel (PTED) was available
  • FLEX N and N+1 were available
  • Turbine-driven Emergency Feedwater Pump available No direct impact to the safety of the public No direct impact to nuclear or radiological safety Enforcement Perspective - Safety Significance

39 Enforcement Perspective

  • Entergy determined the appropriate significance determination for this event is of very low safety significance (Green)

The exposure window commenced on Oct 7, 2024

Repairs were completed on Oct 10, 2024, resulting in a total exposure time of 3.53 day

Repairs were completed within the Technical Specification (TS) allowed outage time of 10 days

  • The Root Cause Evaluation aligns with the overall Performance Deficiency identified by the NRC

40

Closing Comments Joe Sullivan - Site Vice President 08

John Monninger, Regional Administrator Geoffrey Miller, Division Director DORS Nicholas Taylor, Deputy Division Director DORS John Dixon, Branch Chief, PBD Alfred Sanchez, Senior Project Engineer, PBD Cale Young, Senior Reactor Analyst Chris Jewett, ACES David M. Cylkowski, Regional Counsel Dustin Reinert, Senior Reactor Analyst Nick Armstrong, Project Engineer, RIDP, PBD Shaun Hamilton, Project Engineer, RIDP, PBD Victor Lee, Project Engineer, RIDP, PBA NRC Attendees

John Crews, Engineering Consultant Barry Davis, Waterford 3 Engineering Director Kerry Gaston, Risk Engineering Manager John Giddens, Sr. Manager - Regulatory Assurance Otto Gustafson, VP - Regulatory Assurance Monica Peak, Inspection Support - Regulatory Assurance Stephenie Pyle, Director - Regulatory Assurance Joe Sullivan, VP - Waterford 3 John Twarog, Regulatory Assurance Manager - Waterford 3 Sontra Yim, Principal - Socatec Engineering Entergy Attendees

Peters, Ryan Poole, Cordal Ragland, Anntwinette L.

Reinaldo Rodriguez Richard "Scott" Blackwell (DEQ)

Russell Felts Ryan, Daniel Samuel Adams Smith, Jacob Spaargaren, John Sumners, Ryan Taylor, Michael Thomas, William Tim Steadham Tony Nakanishi WEIGANDT Jamie - (AES) - KINECTRICS AES Williams, Ashton Adrienne Landry Alfred Sanchez Andy Patz Angela Rowe Arturo Escamilla Austin Roberts Beatrice Nwafor Beth Alferink Brown, Jesse S: (Constellation Nuclear)

Casey Smith Christopher Litalien Collins, Carl James Dhakal, Shrijan Dylan Freiermuth Eric Brothman Gabb, Sidney Gendusa, Ross Hardy, Jeffery A Haslauer, Daniel Jason Drake Jill De La Garza Jones, Anna Vinson Kent Chambliss Kevin Cook-Smith Kevin Murphy Knowles, Justin W: (Constellation Nuclear)

Lundy Pressley Mills, Cassie Nicholas Hansing Osborne, Kari Patricia Vossmar Perkins, Andrew Matthias Peter Lom Peter, Ramon Virtual Attendees

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