ML21221A260

NRR E-mail Capture - Request for Additional Information Regarding Tva'S Request to Revise Watts Bar, Unit 1 Tech Specs Related to Continuous Opening of the Auxiliary Building Secondary Containment Enclosure Boundary

ML21221A260
Person / Time
Site:	Watts Bar
Issue date:	08/09/2021
From:	Michael Wentzel NRC/NRR/DORL/LPL2-2
To:	Wells R Tennessee Valley Authority
References
L-2021-LLA-0035
Download: ML21221A260 (5)

Text

From: Wentzel, Michael Sent: Monday, August 9, 2021 2:35 PM To: Wells, Russell Douglas Cc: Green, Kimberly; Haeg, Luke

Subject:

Request for Additional Information Regarding TVA's Request to Revise the Watts Bar Nuclear Plant, Unit 1 Technical Specifications Related to Continuous Opening of the Auxiliary Building Secondary Containment Enclosure Boundary (EPID L-2021-LLA-0035)

Attachments: RAI Regarding Request to Revise the Watts Bar, Unit 1 TSs Related to the Aux Building Secondary CEB - EPID L-2021-LLA-0035.pdf

Dear Mr. Wells,

By letter dated March 3, 2021 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML21062A267), Tennessee Valley Authority (TVA) requested changes to the Technical Specifications (TS) for Watts Bar Nuclear Plant (Watts Bar), Unit 1. The proposed changes would revise TS 3.7.12, Auxiliary Building Gas Treatment System (ABGTS), to allow the auxiliary building secondary containment enclosure boundary to be opened, at specific controlled access points, on a continuous basis during the Watts Bar, Unit 2, Cycle 4 refueling outage.

The U.S. Nuclear Regulatory Commission (NRC) staff is reviewing your submittal and has identified areas where additional information is needed to complete its review.

A draft request for additional information (RAI) was previously transmitted to you by email dated July 29, 2021. At your request, a clarification call was held on August 9, 2021, to clarify the NRC staffs draft RAI. As a result of that call, it was determined that IOLB RAI 1b would be addressed by SCPB RAI 2. Therefore, IOLB RAI 1b was removed. Additionally, the inclusion of test acceptance criteria as part of the response to SCPB RAI 2 was added, and IOLB RAI 2 was reworded to more specifically request confirmation of the tracking methods for openings.

As agreed during the call, a response to the attached RAI is requested within 30 days from the date of this email.

The NRC staff considers that timely responses to RAIs help ensure sufficient time is available for staff review and contribute toward the NRCs goal of efficient and effective use of staff resources. If circumstances result in the need to revise the requested response date, please contact me at (301) 415-1627 or via email at Kimberly.Green@nrc.gov.

Sincerely, Michael Wentzel, Project Manager Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

Hearing Identifier: NRR_DRMA Email Number: 1309 Mail Envelope Properties (DM8PR09MB7093E4C091E5694907ADCD82E7F69)

Subject:

Request for Additional Information Regarding TVA's Request to Revise the Watts Bar Nuclear Plant, Unit 1 Technical Specifications Related to Continuous Opening of the Auxiliary Building Secondary Containment Enclosure Boundary (EPID L-2021-LLA-0035)

Sent Date: 8/9/2021 2:34:41 PM Received Date: 8/9/2021 2:34:00 PM From: Wentzel, Michael Created By: Michael.Wentzel@nrc.gov Recipients:

"Green, Kimberly" <Kimberly.Green@nrc.gov>

Tracking Status: None "Haeg, Luke" <Lucas.Haeg@nrc.gov>

Tracking Status: None "Wells, Russell Douglas" <rdwells0@tva.gov>

Tracking Status: None Post Office: DM8PR09MB7093.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 1978 8/9/2021 2:34:00 PM RAI Regarding Request to Revise the Watts Bar, Unit 1 TSs Related to the Aux Building Secondary CEB

- EPID L-2021-LLA-0035.pdf 96884 Options Priority: Normal Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

DRAFT REQUEST FOR ADDITIONAL INFORMATION TENNESSEE VALLEY AUTHORITY WATTS BAR NUCLEAR PLANT, UNIT 1 DOCKET NO. 50-390 CONTINOUS OPENING OF AUXILIARY BUILDING SECONDARY CONTAINMENT ENCLOSURE BOUNDARY SCPB By letter dated March 3, 2021 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML21062A267), Tennessee Valley Authority (TVA) submitted a license amendment request (LAR) for Watts Bar Nuclear Plant (Watts Bar or WBN), Unit 1. The proposed amendment would modify the existing Note associated with the Limiting Condition for Operation (LCO) for Unit 1 Technical Specification (TS) 3.7.12, "Auxiliary Building Gas Treatment System (ABGTS), to allow the auxiliary building secondary containment enclosure (ABSCE) boundary to be opened, at specific controlled access points, on a continuous basis during the Watts Bar, Unit 2, Cycle 4 refueling outage (U2R4) when the Unit 2 replacement steam generators (RSGs) are scheduled to be installed.

The ABSCE boundary is shared between Units 1 and 2. Because Unit 1 will be operating during U2R4, continuous opening of the ABSCE boundary during the U2R4 replacement activities would require Watts Bar, Unit 1, to enter the LCO for TS 3.7.12. Therefore, TVA is proposing a one-time exception to LCO Note for the duration of U2R4 that would allow breaches of the ABSCE boundary on a continuous basis under administrative controls that will ensure that the ABSCE can be closed consistent with the safety analysis.

Section 15.5.3 of the Watts Bar Dual-Unit Updated Final Safety Analysis Report (UFSAR) contains the analysis of the environmental consequences of a postulated loss-of-coolant accident (ADAMS Accession No. ML20323A316). This analysis assumes that activity leaking to the auxiliary building (AB) is directly released to the environment for the first 4 minutes, after which it is then released through the ABGTS system filter.

The LAR stated that detailed procedural controls exist to ensure the ABSCE can be closed consistent with the safety analysis and that the controls ensure the breach opening can be closed within 2 minutes of notification from the main control room (MCR), which allows sufficient time to be able to draw down the ABSCE to -0.25 inch water gauge within 4 minutes consistent with the safety analysis in Section 15.5.3 of the UFSAR.

SCPB RAI 1 LAR Section 3.2.2, Unit 2 RSG Outage Activities, states:

In a typical outage, the Unit 2 containment is considered part of the ABSCE when the Unit 2 Upper and Lower Containment Personnel Air Locks and the Unit 2 Equipment Hatch are open, and therefore these openings are not considered breaches of the ABSCE. However, during the RSG Outage, temporary openings

in the Unit 2 shield building concrete dome and steel containment vessel will be created in order to remove the existing SGs and install the RSGs. These temporary openings cannot be closed within the required time frame to remain consistent with the safety analysis. Thus, once these openings are created, the ABSCE boundary will be moved to exclude the Unit 2 containment. Therefore, these two Air Locks and the Equipment Hatch will be considered breaches of the ABSCE when the temporary openings in the shield building dome are created.

Regarding the statement that the Unit 2 containment is part of Unit 1 ABSCE when the containment personnel air locks and the equipment hatch are open during a Unit 2 outage:

a. Clarify if the containment personnel air locks and equipment hatch openings are administratively controlled throughout the period when the airlocks and hatch are open or only during the period when the temporary openings through the shield building concrete dome and steel containment vessel exist.

b. Confirm ABGTS drawdown tests include the containment volume as part of ABSCE boundary to support the statement that outage unit (Unit 2) containment is considered part of the ABSCE of the operating unit (Unit 1).

SCPB RAI 2 Regarding the Unit 2 Containment Equipment Hatch (Room 757.0-A15, also known as the shield building equipment hatch sleeve), the LAR states: This access is intended to be used principally by workers and equipment for access to primary containment areas. During the RSG Outage, this hatch will be secured as needed by a temporary ABSCE door (WBN-0-DOOR-410-R003) capable of being closed within two minutes.

The closure of ABSCE breaches by administrative controls are accomplished by permanent equipment (e.g., doors, airlocks) that are part of the ABGTS drawdown tests, except for a temporary ABSCE door that would take the place of the equipment hatch. Provide information (including test acceptance criteria) regarding the temporary door and its leak tightness to show that its impact, if any, on the capability of ABGTS to draw down ABSCE to the required negative pressure within the acceptable time is minimal and acceptable.

IOLB In the LAR, TVA cited the U.S. Nuclear Regulatory Commissions (NRC) letter to TVA, Watts Bar Nuclear Plant, Units 1 and 2 - Issuance of Amendments Regarding Auxiliary Building Gas Treatment System (CAC Nos. MF8526 and MF8527), dated October 17, 2017 (ADAMS Accession No. ML17236A057) as a precedent. TVA stated that the change proposed in the current LAR, to allow continuous opening of the ABSCE boundary under administrative controls to ensure the ABSCE can be closed consistent with the safety analysis, is similar to the approved SE dated October 17, 2017. The exception is that the precedent was for the intermittent opening of the ABSCE boundary as opposed to the continuous opening for the current LAR.

To inform the SE, dated October 17, 2017, TVA provided a supplement dated May 5, 2017 (ADAMS Accession No. ML17125A244). In that supplement, TVA stated that in accordance with TVA procedure TI-65, Breaching the Containment Annulus, ABSCE, or MCRHZ [main

control room habitability zone] Pressure Boundaries, the following administrative controls are used for ABSCE breaches in excess of the total allowable breach area:

The breach opening can be closed at all times within 2 minutes of notification from the MCR. This allows sufficient time to be able to drawdown the ABSCE to -0.25 in.

WG within 4 minutes.

Individuals performing the administrative actions are stationed at both the breach location and in the MCR with clear communications established.

Means to restore the breach, if required, are staged (e.g., blind flanges, foam penetrations, fabric roll-up doors).

Non-routine ABSCE boundary breaches require that a mock-up/walk-through demonstration be performed prior to the entry to ensure that the breach can be restored within two minutes.

Attachment 5 to TI-65 ensures that the administrative controls are in place prior to opening the breach and requires a senior reactor operator approval to commence work.

In Section 3.2.1, ABSCE Operability to Support Unit 1 Operation during the RSG Outage, of the current LAR, TVA stated:

For the continuous openings of the ABSCE boundary to support the WBN Unit 2 RSG project, the same proceduralized controls reviewed by NRC in Reference 1

[SE dated October 17, 2017] will remain in effect. Therefore, the ability to ensure the ABSCE can be closed consistent with the safety analysis during the RSG Outage is assured.

The NRC staff requests the following information to ensure that differences between the cited precedent and the current LAR are non-material and would not prevent operators from completing actions needed to close the breaches.

IOLB RAI 1 Confirm that each of the designated individuals (1 person at each breach for a total of 4, at any given time) stationed at their respective breach does not have incidental duties that could delay them from performing the administrative action to close the breach within the 2 minutes of notification from the MCR.

IOLB RAI 2 In the supplement dated May 5, 2017, TVA stated the following:

In accordance with TVA procedure TI-65, Breaching the Containment Annulus, ABSCE, or MCRHZ Pressure Boundaries, a breach tracking permit (BTP) is used to control any planned breach entries of the ABSCE boundary.

Additionally, ABSCE boundary breaches are logged and tracked using a breach permit tracking log. This log includes the breach open area (BOA), the start and stop times for the breach, and the BTP number.

Confirm that the methods for tracking intermittent openings is the same for continuous openings.