ML22077A806

Summary of the February 1, 2022, Regulatory Conference Between Energy Harbor, Davis-Besse Nuclear Power Station and the Nuclear Regulatory Commission

ML22077A806
Person / Time
Site:	Davis Besse
Issue date:	03/23/2022
From:	David Curtis Division of Reactor Safety III
To:	Energy Harbor Nuclear Corp
References
EA-21-176
Download: ML22077A806 (6)

Text

March 23, 2022 EA-21-176 LICENSEE: ENERGY HARBOR NUCLEAR CORP.

FACILITY: DAVIS-BESSE NUCLEAR POWER STATION

SUMMARY

OF THE FEBRUARY 1, 2022, REGULATORY CONFERENCE BETWEEN ENERGY HARBOR, DAVIS-BESSE NUCLEAR POWER STATION AND THE NUCLEAR REGULATORY COMMISSION On February 1, 2022, representatives of Energy Harbor Nuclear Corp. (the licensee) met with the U.S. Nuclear Regulatory Commission (NRC) personnel in the NRC Region III office located in Lisle, Illinois, to discuss the apparent violation identified in NRC Special Inspection Reactive Report 05000346/2021050. The conference was held at the request of the licensee and open to the public for observation. The licensee presented new information relevant to the agencys significance determination and failure analysis of the Emergency Diesel Generator (EDG) #1 field flash selector switch (FFSS). The licensee also presented views on the identified apparent violation.

The licensee disagreed with the NRCs identified performance deficiency, the failure to establish preventive maintenance schedule for the FFSS. The licensee argued that, even if the NRC ultimately concludes that the licensee failed to establish a preventive maintenance schedule related to the FFSS, the identified performance deficiency is not the cause of the EDG failure and would result in a significance determination of GREEN. The licensee also determined that, should the performance deficiency be considered as the cause of the EDG failure, the significance determination would be WHITE.

The licensee presented a summary of the EDG #1 failure during a fast start surveillance test, which is required to be performed every 184 days. The EDGs engine reached rated speed, but the electrical field did not flash. The EDG was shut down in accordance with procedure and during the process of the shutdown, the FFSS was taken from the fast start position to the slow start position. Operators saw indication of the electrical field being flashed when the FFSS was repositioned. Operators checked the FFSS for electrical continuity after the shutdown and found that the FFSS failed two out of five times.

The licensee described the actions it has taken in response to the EDG #1 failure. The actions taken included the following: (1) replacement of the existing FFSS with a new FFSS on May 28, 2021; (2) adding test procedure enhancements to check the electrical continuity of the FFSS after operation; (3) adding a step to the Emergency Operating Procedure to manually override the field flash selector switch; (4) initiating enhanced preventive maintenance to inspect and replace FFSS if necessary; and (5) performing an EDG reliability assessment. The licensee also described other modifications it is considering, including installation of an indicator light for fast start switch position and modifying the field flash circuitry to eliminate the vulnerability.

2 The licensee presented a shorter timeline for the FFSS potential failed state than the timeline the NRC used in its probabilistic risk assessment. The licensee stated the FFSS was successfully tested during a fast start surveillance test on November 12, 2020, and subsequently tested again on December 10, 2020, for the monthly slow start test. Therefore, the licensee determined that the period the FFSS could have been in a failed state should be 99 days instead of the 114 days used by the NRC. The licensees basis for exposure time was:

Between November 12, 2021 and December 10, 2021, the switch was known to be functional since the FFSS was not moved after the successful fast start test. (0 days)

Between December 10, 2021 and April 29, 2022, the failure state of the FFSS was unknown and the t/2 philosophy should be used. (140 days/2 = 70 days)

Between the slow start test on April 29, 2022, when the FFSS was returned to the fast start position, and the fast start test failure on May 28, 2022, the FFSS was known to be failed. (29 days)

For a total exposure time of 99 days. (29 + 70 days)

The licensee also claimed that the human error probability used by the NRC was too high and that some credit should be considered for recovery. Therefore, based on their analysis the human error probability should be 0.72 vice the 0.91 used by the NRC. The licensee also summarized the dominant fire scenarios. They claimed that there were two potential thermo-hydraulic assumptions that if considered with the fire assumptions would lower the change in core damage frequency by 49 percent.

The licensee explained its position on the failure analysis, including the findings of two independent contractors, MPR and Associates and Exelon Power Labs. Through non-intrusive and intrusive testing, these contractors determined the failure mechanism to be foreign material and not silver sulfidation as described by the NRC. The licensee explained that 160 cycles of the FFSS were performed and that no resistance readings indicated a failure would have occurred on the fast start contacts. Additionally, these contractors observed: (1) proper switch alignment and spring compression upon disassembly; (2) that the operator mechanism was in very good condition; and (3) traces of nickel were identified on stationary contact 3C (stationary fast start contact) using a scanning electron microscope. The licensee postulated that the cause of the FFSS failure was that nickel, from the nickel brass plated terminal screws, impacted the contact surface and prevented its operation.

The NRC questioned the licensee about their quarantine process and whether it was properly followed following the FFSS failure. The licensee described the control of the FFSS from the time it was removed from the system on April 28, 2021, until when it was prepared for shipment to MPR on September 9, 2021. When questioned about the control of the switch during the time between the failure and shipment to MPR, the licensee described that although the switch was manipulated by the system engineer, including the loosening and re-snugging of the main bolts by one quarter of an inch, and removal and reinstallation of the front end of the switch this had no bearing on the results of the independent contractors analysis.

The licensee concluded their presentation by describing three examples of operating experience at other plants that were considered and found not to be comparable to the failure seen at Davis-Besse Nuclear Power Station. The licensee stated that preventive maintenance would

3 not have prevented the FFSS failure and further, even if NRC concluded that a performance deficiency related to preventive maintenance of the FFSS existed, such failure would not have resulted in the May 27, 2021, failure of EDG #1.

Throughout the licensees presentation the NRC asked numerous clarifying questions. Most questions were focused on the licensees recovery actions and the failure analysis of the FFSS.

NRC asked questions regarding the availability and comprehensiveness of the licensees procedures, training response times, available resources during these worst-case fire scenarios, details regarding possible silver sulfide build up in the contacts as credible cause of the FFSS failure(s), and details associated with preventive maintenance of the FFSS in relationship to the failure.

The licensee provided answers to most of NRCs questions. The licensee did not have the information to answer the following questions and agreed to provide the answers no later than February 16, 2022. The NRC requested the industrys preventive maintenance template for this type of switch, and how fire assumptions documented in letters to the NRC during the licensees transition to NFPA 805 would impact the change in core damage frequency. The NRC also requested information about how re-shutting DC breakers to energize the control and instrumentation circuitry for EDG #1 during an extended loss of AC power scenario would impact the licensees timing analysis which was used to support compliance with the Fukushima orders.

At the close of the business portion of the meeting, members of the public were invited to ask questions and interact with NRC participants. Members of the public did not make statements or ask questions of the NRC participants.

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

NRC Presentation ML22028A397 Licensee Presentation ML22028A392 Licensee Response to NRC Questions ML22049A066 Signed by Curtis, David on 03/23/22 D. Curtis, Deputy Director Division of Reactor Safety Docket No.: 05000346 License No.: NPF-3

Enclosure:

1. List of Attendees cc: Distribution via LISTSERV

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SUMMARY

OF THE FEBRUARY 1, 2022, REGULATORY CONFERENCE BETWEEN ENERGY HARBOR, DAVIS-BESSE NUCLEAR POWER STATION AND THE NUCLEAR REGULATORY COMMISSION DISTRIBUTION:

Jessie Quichocho Linda Howell RidsNrrDorlLpl3 RidsNrrPMDavisBesse Resource RidsNrrDroIrib Resource John Giessner Mohammed Shuaibi Shelbie Lewman Allan Barker DRPIII DRSIII Mike Franovich Russell Felts Russell Chazell Juan Peralta Wendell Morton Anthony Masters Michelle Hayes Kenneth Lambert David Jones Kenn Miller Reinaldo Rodriguez Mark Lombard Meena Khanna Antonios Zoulis Blake Purnell Viktoria Mitlyng Prema Chandrathil Alex Garmoe Sarah Bakhsh Susan Spicer Julie Winslow David Aird Carolyn Wolf ADAMS Accession Number: ML22077A806 Publicly Available Non-Publicly Available Sensitive Non-Sensitive OFFICE RIII RIII RIII NAME RSkokowski:mb SLewman DCurtis DATE 03/18/2022 03/21/2022 03/23/2022 OFFICIAL RECORD COPY

LIST OF ATTENDEES NRC ATTENDEES:

J. Giessner, Regional Administrator M. Shuaibi, Deputy Regional Administrator M. Franovich, Director of the Division of Risk Assessment D. Curtis, Deputy Director of the Division of Reactor Safety J. Lara, Director of the Division of Reactor Projects R. Felts, Deputy Director of the Division of Reactor Oversight S. Lewman, Acting Enforcement Officer R. Chazell, Regional Counsel J. Peralta, Office of Enforcement Branch Chief B. Dickson, Division of Reactor Projects Branch Chief R. Skokowski, Division of Reactor Safety Branch Chief W. Morton, Electrical Engineering Branch, Branch Chief A. Masters, Reactor Assessment Branch, Branch Chief M. Hayes, Advanced Reactors Engineering Branch 1, Branch Chief J. Hanna, Senior Risk Analyst L. Kozak, Senior Risk Analyst K. Lambert, Senior Enforcement Specialist D. Jones, Senior Enforcement Specialist K. Miller, Senior Electrical Engineer R. Rodriguez, Reliability and Risk Analyst K. Barclay, Reactor Inspector K. Fay, Reactor Inspector Others, as designated NRC OBSERVERS:

S. Atack, Acting Director of the Division of Reactor Safety M. Lombard, Director of the Office of Enforcement J. Heisserer, Deputy Director of the Division of Reactor Projects M. Khanna, Deputy Director of the Division of Risk Assessment A. Zoulis, Branch Chief of Probabilistic Risk Assessment Branch M. Ziolkowski, Division of Reactor Safety Acting Branch Chief B. Purnell, Project Manager of Operating Reactor Licensing V. Mitlyng, Senior Public Affairs Officer P. Chandrathil, Public Affairs Officer A. Barker, Regional Governmental Liaison Officer M. Holmberg, Senior Reactor Inspector D. Kimble, Senior Resident Inspector D. Mills, Senior Resident Inspector A. Garmoe, Senior Reactor Analyst D. Szwarc, Senior Reactor Analyst S. Bakhsh, Allegation/Enforcement Specialist S. Spicer, Allegation/Enforcement Specialist J. Nance, Operations Engineer D. Turpin, Reactor Engineer J. Gewargis, Reactor Engineer J. Winslow, Reactor Systems Engineer D. Aird, Reactor Operations Engineer Enclosure 1

R. Cassara, Resident Inspector T. Ospino, Resident Inspector J. Weigandt, Resident Inspector M. Abuhamdan, Reactor Inspector E. Magnuson, Reactor Inspector J. Masse, General Engineer M. Siddiqui, General Engineer H. Marchlewski, General Engineer L. Caponi, General Engineer J. Havertape, Reliability and Risk Analyst A. Mihalik, Reliability and Risk Analyst J. Reed, Health Physicist D. Bogedain, Administrative Assistant ENERGY HARBOR NUCLEAR CORP ATTENDEES:

Terry Brown, Site Vice President Greg Michael, Engineering Director Cleve Wilson, Strategic Engineering Manager Brian Zsenyuk, Strategic Engineering Supervisor Alan Filipiak, Assistant Operations Manager, active SRO License Dan Harnett, Operations Manager Rob Oesterle, Regulatory Compliance Manager Aaron Quaderer, Probabilistic Risk Analysis Engineer Robin Ritzman, Principal Regulatory Compliance Engineer Phil Lashley, Fleet Licensing Manager Gerry Wolf, Nuclear Compliance Supervisor John Cunningham, MPR Associates Gary Thompson, MPR Associates 2