ML25176A107
| ML25176A107 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar  |
| Issue date: | 06/26/2025 |
| From: | Kimberly Green Plant Licensing Branch II |
| To: | Tennessee Valley Authority |
| Green K | |
| Shared Package | |
| ML25178A292 | List: |
| References | |
| EPID L-2025-LRM-0074 | |
| Download: ML25176A107 (1) | |
Text
June 26, 2025 LICENSEE:
Tennessee Valley Authority FACILITY:
Watts Bar Nuclear Plant, Unit 2
SUBJECT:
SUMMARY
OF JUNE 5, 2025, PUBLIC TELECONFERENCE WITH TENNESSEE VALLEY AUTHORITY TO DISCUSS A PROPOSED EMERGENCY LICENSE AMENDMENT REQUEST AND EXEMPTION RELATED TO TECHNICAL SPECIFICATION 3.3.1 FOR WATTS BAR NUCLEAR PLANT, UNIT 2 (EPID L-2025-LRM-0074)
On June 5, 2025, the U.S. Nuclear Regulatory Commission (NRC) staff held a public meeting via teleconference with representatives of the Tennessee Valley Authority (TVA) to discuss a proposed emergency license amendment request (LAR) and exemption for Watts Bar Nuclear Plant (Watts Bar), Unit 2. The meeting notice and agenda for this meeting, dated June 5, 2025, are available at Agencywide Documents Access and Management System (ADAMS) Accession No. ML25156A047. A list of the meeting attendees is enclosed.
TVA requested the meeting to discuss its planned submittal of an emergency LAR for Watts Bar, Unit 2, that would revise Technical Specification (TS) 3.3.1, Reactor Trip System (RTS)
Instrumentation, and an exemption request.
TVA stated that it had to declare one of the three pressurizer high water level transmitters inoperable and place the affected channel in the trip condition. This means that if one more level transmitter were to automatically trip, it would cause the Watts Bar Unit 2 reactor to automatically trip and shut down. This places the unit in a single point vulnerability. At the time, two other TVA reactor units were shut down. To avoid the possibility of a third unit shutting down during higher temperature weather, TVA stated that it plans to request the one-time LAR to allow the inoperable channel to be placed in bypass, thereby essentially changing the logic to cause a reactor trip from two-out-of-three to two-out-of-two. The proposed TS change would add a one-time note to the Required Action for Condition X that would allow the inoperable channel to be bypassed until it can be restored to operable status, and would include a reference to the LAR that would identify compensatory measures that shall be in place for the duration of the note, which would expire when the transmitter is returned to operable status or July 1, 2025, whichever is earliest.
Because the circumstances for the LAR do not meet the criteria for emergency circumstances in paragraph 50.91(a)(5) of Title 10 of the Code of Federal Regulations, TVA stated that it would also submit an exemption request to allow the LAR to be considered under emergency circumstances. TVA briefly described what it plans to include in the exemption request, including the special circumstance that it believes is applicable to the request.
TVA detailed the logic for the reactor protection system and the level transmitters in question.
TVA also described the risk assessment it performed to determine the change in risk due to the unavailability of the level transmitter. TVA stated that the specific level transmitters are not modeled in the probabilistic risk assessment (PRA), so it used a surrogate event to estimate the risk and stated that the risk values were less than 1 x 10-11, which is considered to be very small by the NRCs regulatory guidance. The NRC staff questioned whether TVA considered a common cause failure. TVA confirmed that it had performed a sensitivity study, and the risk numbers were about a decade (factor of 10) higher.
The NRC staff asked clarifying questions regarding the action TVA would take if the July 1st deadline arrived and it was not able to return the transmitter to operable status and if a second channel was determined to be inoperable.
Because TVA plans to request approval of the emergency LAR by June 8, 2025, the NRC staff suggested the following items be included in the LAR to assist in an expedient review:
a description of the surrogate that was used in the PRA a description of sensitivity study that was performed for the common cause failure consideration a brief discussion of the Maintenance Rule A.4 program (for monitoring risk) reference to the accident analyses in the updated final safety analysis report where credit for the pressurizer high water level function is mentioned a description of the power supplies for the level transmitters TVA stated that it plans to submit the emergency LAR and exemption request by 10:00 p.m. on June 5, 2025.
No regulatory decisions were made at this meeting.
No comments or public meeting feedback forms were received.
Please direct any inquiries to me at 301-415-1627 or Kimberly.Green@nrc.gov.
/RA/
Kimberly J. Green, Project Manager Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-391
Enclosure:
List of Attendees cc: Listserv
Enclosure LIST OF ATTENDEES JUNE 5, 2025, TELECONFERENCE WITH TENNESSEE VALLEY AUTHORITY PROPOSED EMERGENCY LICENSE AMENDMENT REQUEST AND EXEMPTION REGARDING TECHNICAL SPECIFICATION 3.3.1 WATTS BAR NUCLEAR PLANT, UNIT 2 Name Organization Kim Green U.S. Nuclear Regulatory Commission (NRC)
Bob Pascarelli NRC Norbert Carte NRC Rob Elliott NRC Robert Wehrmann NRC Todd Hilsmeier NRC Ching Ng NRC Shivani Mehta NRC Tarico Sweat NRC Jobin Daniel NRC Ryan Taylor NRC Evan Robinson NRC Russ Wells Tennessee Valley Authority (TVA)
Amber Aboulfaida TVA Gerry Kindred TVA Beau Eckermann TVA Kim Hulvey TVA Mark Nicholson TVA Jonathan Gore TVA Bill Victor TVA Jesse Baron TVA Matt Harding TVA Jarrett Lavasseur TVA Keith Skubisz TVA David Lively TVA Shawna Hughes TVA Ben Reece TVA Jeremy Thompson TVA Dan Kearnanghan TVA
ML25178A292 (Package)
ML25156A047 (Meeting Notice)
ML25176A107 (Meeting Summary)
NRC-001 OFFICE NRR/DORL/LPL2-2/PM NRR/DORL/LPL2-2/LA NRR/DORL/LPL2-2/BC NRR/DORL/LPL2-2/PM NAME KGreen ABaxter DWrona KGreen DATE 06/24/2025 06/26/2025 06/26/2025 06/26/2025