ML24158A300

Summary of May 6, 2024, Public Meeting with Tennessee Valley Authority to Discuss the Potential for a License Amendment Request Regarding the Control Room Envelope and Selective Use of an Alternative Source Term

ML24158A300
Person / Time
Site:	Watts Bar
Issue date:	06/11/2024
From:	Kimberly Green Plant Licensing Branch II
To:	Tennessee Valley Authority
Green K
Shared Package
ML24158A302	List: ML24158A300
References
EPID L-2024-LRM-0061
Download: ML24158A300 (5)

Text

June 11, 2024

LICENSEE: Tennessee Valley Authority

FACILITY: Watts Bar Nuclear Plant, Units 1 and 2

SUMMARY

OF MAY 6, 2024, PU BLIC MEETING WITH TENNESSEE VALLEY AUTHORITY TO DISCUSS THE POTENTIAL FOR A LICENSE AMENDMENT REQUEST REGARDING THE CONTROL ROOM ENVELOPE AND SELECTIVE USE OF AN ALTERNATIVE SOURC E TERM (EPID L-2024-LRM-0061)

On May 6, 2024, the U.S. Nuclear Regulatory Commission (NRC) staff held a preliminary public meeting via teleconference with representatives of the Tennessee Valley Authority (TVA, the licensee) to discuss the potential for a proposed license amendment request (LAR) for Watts Bar Nuclear Plant, Units 1 and 2 (Watts Bar). The meeting notice and agenda for this meeting, dated April 24, 2024, are available at Agencywi de Documents Access and Management System (ADAMS) Accession No. ML24115A076. The licensees slides for the meeting are available at ML24127A041. A list of the meeting attendees is enclosed.

TVA stated that it is considering submitting an LAR that would propose changes to the note for the Limiting Condition for Operation (LCO) for Watts Bar TS 3.7.10, Control Room Emergency Ventilation System (CREVS), and uses selective implementation of an alternative source term (AST) during a loss-of-coolant accident (LOCA), and is seeking NRC staff feedback.

TVA stated that the reason for the proposed changes is to prevent entry into TS 3.7.10, Condition B (i.e., one or more CREVS trains inoperable due to inoperable control room envelope (CRE) boundary in Mode 1, 2, 3, or 4) every time a CRE boundary door is left ajar.

When a door is left ajar it causes both trains of CREVS to be inoperable, which has associated reporting requirements, i.e., licensee event report (LER). TVA noted that Watts Bar has submitted 12 LERs for this issue. The NRC a sked about proposed corrective action for one the LERs--to develop and install an engineering feature to inform personnel closing the door that it is fully shut and latched. TVA stated that it did not find any reliable mechanical features and that they were found to be less reliable than TVA staff closing the doors.

TVA plans to propose an addition to the end of the Note associated with Limiting Condition for Operation (LCO) 3.7.10 that would say, that ensure the CRE can be closed consistent with the safety analysis. The associated TS Bases would be revised to state this as well.

Additionally, TVA plans to propose expanding the personnel that can administratively open the doors to personnel responsible for responding to an abnormal pressurization alarm. Lastly, TVA plans to add a statement to the Bases regarding restoration of the CRE boundary within 10 minutes in accordance with the Updated Final Safety Analysis Report (UFSAR) Chapter 15.5. This last statement is related to TVAs plan to selectively implement an AST for the LOCA.

Regarding the selective implementation of the AST, TVA noted that Regulatory Guide 1.183, Alternative Radiological Source Terms for Evaluating Design Basis Accidents at Nuclear Power Reactors, stated that the onset of the gap release phase may be assumed to be 10 minutes for facilities licensed for leak-before-break (LBB) methodology, for which Watts Bar is licensed and would implement for a LOCA. This would allow the CRE door(s) to be open for up to 10 minutes without impacting the current analysis. TVA stated that no reanalysis would be performed for the LOCA; however, the analyses would be revised to account for the delay. TVA also stated that it would maintain the current source term and acceptance criteria based on Technical Information Document (TID)-14844, Calculation of Distance Factors for Power and Test Reactor Sites.

The NRC staff asked TVA what type of analyses it plans to submit to support the 10-minute gap credit. TVA replied that it is seeking feedback on what the NRC staff would need to review. The NRC staff noted that for selective implementation of an AST, RG 1.183 states that re-analysis of radiological calculations may not be necessary if the modified elapsed time remains a fraction (e.g., 25%) of the time between accident initiation and the onset of the gap release phase. The staff encouraged TVA to include a justification for the fraction that it uses in its analyses. The NRC staff also suggested that the analyses shoul d include any impact on time critical response actions.

The staff asked if TVA has procedures in place for the administrative opening of the doors and for breaches. TVA said that it has procedures and that if a breach is large enough, someone has to be posted at the location. The NRC sta ff asked if the proposed change would be limited to the doors, or if it would also be applicable to other breaches such as dampers. TVA replied that it would only apply to the main control room doors. The NRC staff suggested that the LAR specify the applicability of the Note to the doors. The NRC staff asked about any mitigating actions TVA performs for Condition B. TVA stated personnel protection (e.g., self-contained breathing apparatus and potassium iodide tablets) is readily available.

Referring to the LERs that have been submitted, the NRC staff asked TVA how long it takes for a control room alarm to be generated when a door is left open. TVA stated that an alarm would have been generated in ~5 to 6 minutes, but in reality, its more like 90 seconds.

The NRC staff provided feedback to TVA; however, 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 Nos. 50-390 and 50-391

Enclosure:

List of Attendees

cc: Listserv

LIST OF ATTENDEES

MAY 6, 2024, TELECONFERENCE WITH TENNESSEE VALLEY AUTHORITY

POTENTIAL FOR A PROPOSED LICENSE AMENDMENT REQUEST REGARDING

CONTROL ROOM ENVELOPE AND SELECTIVE USE OF ALTERNATIVE SOURCE TERM

FOR WATTS BAR NUCLEAR PLANT, UNITS 1 AND 2

Name Organization Kim Green U.S. Nuclear Regulatory Commission (NRC)

Rao Karipeneni NRC Joshua Wilson NRC Robert Beaton NRC Tony Sierra NRC David Garmon NRC Gordon Curran NRC Bill Rautzen NRC Robert Wehrmann NRC Lou McKown NRC

Shawna Hughes Tennessee Valley Authority (TVA)

Russ Wells TVA Doug Pollack TVA Jerry Thompson TVA Chris Kerlin TVA Keith Skubisz TVA Stuart Rymer TVA

Enclosure

ML24158A302 (Package)

ML24158A300 (Meeting Summary)

ML24115A076 (Meeting Notice)

ML24127A041 (Slides)

OFFICE NRR/DORL/LPL2-2/PM NRR/DORL/LPL2-2/LA NRR/DORL/LPL2-2/BC NRR/DORL/LPL2-2/PM NAME KGreen ABaxter (KGoldstein for) DWrona KGreen

DATE 06/06/24 06/10/24 06/11/24 06/11/24