ML23248A348

NRR E-mail Capture - for Your Action - Request for Additional Information (RAI) 6 - Vogtle - TSTF-339 LAR (L-2023-LLA-0053)

ML23248A348
Person / Time
Site:	Vogtle
Issue date:	09/05/2023
From:	John Lamb Plant Licensing Branch II
To:	Pournaras D Southern Nuclear Operating Co
References
L-2023-LLA-0053
Download: ML23248A348 (4)

Text

From: John Lamb Sent: Tuesday, September 5, 2023 11:24 AM To: Pournaras, DeLisa S.

Cc: Chamberlain, Amy Christine

Subject:

For Your Action - Request for Additional Information (RAI) #6 - Vogtle - TSTF-339 LAR (L-2023-LLA-0053)

DeLisa and Ken,

By letter dated April 11, 2023 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23101A159), Southern Nuclear Operating Company (SNC, the licensee) submitted a license amendment request (LAR) for Vogtle Electric Generating Plant (Vogtle), Units 1 and 2. The proposed amendments would revise TS 2.1.1, Reactor Coolant Safety Limits, (TS) 3.3.1, Reactor Trip System (RTS) Instrumentation, TS 3.4.1, Reactor Coolant System (RCS) Pressure, Temperature, and Flow Departure from Nucleate Boiling (DNB) Limits, and TS 5.6.5, Core Operating Limits Report (COLR), to adopt most of the TS and COLR changes described in Appendix A and Appendix B of Westinghouse topical report WCAP-14483-A, to relocate several cycle-specific parameter limits from the TS to the COLR.

The amendments follow the guidance of technical specification task force (TSTF) change traveler TSTF-339-A, Revision 2. Along with the parameter relocations, the amendments also modify the Vogtle, Units 1 and 2, TS 5.6.5, to include WCAP-8745-P-A and WCAP-11397-P-A, and to revise the TS applicability for the WCAP-9272-P-A, in the list of the U.S. Nuclear Regulatory Commission (NRC) approved methodologies used to develop the cycle-specific COLR. In addition, the amendments revise an error to the TS 3.3.1 depiction of an equation.

The NRC staff reviewed the submittal dated April 11, 2023, and determined that additional information is needed to complete its review.

On August 10, 2023, the NRC staff provided draft RAI questions to SNC to make sure that the RAI is understandable, the regulatory basis is clear, to ensure there is no proprietary information, and to determine if the information was previously docketed. On September 5, 2023, a clarifying call was held between the NRC staff and SNC, and SNC stated that it would provide the RAI response within 30 days from the date of this email.

If you have any questions, you can contact me at 301-415-3100.

Sincerely, John

REQUEST FOR ADDITIONAL INFORMATION (RAI)

By application dated April 11, 2023, (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23101A159), Southern Nuclear Operating Company, Inc. (SNC, the licensee) requested changes to the Technical Specifications (TSs) for Renewed Facility Operating License Nos. NPF-68 and NPF-81 for Vogtle Electric Generating Plant (Vogtle), Units 1 and 2, respectively.

The proposed changes would relocate cycle-specific parameters from the TSs to the Core Operating Limits Report (COLR), a licensee-controlled document, by adopting Technical Specification Task Force (TSTF) Traveler TSTF-339, Revision 2, Relocate TS Parameters to COLR, (ML003723269).

The U.S. Nuclear Regulatory Commission (NRC) staff reviewed the license amendment request (LAR) and determined that the NRC staff needs additional information to complete its review.

Regulatory Basis

Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Domestic Licensing of Production and Utilization Facilities, establishes the fundamental regulatory requirements.

Section 50.36 of 10 CFR, Technical specifications, details the content and information that a facility's TSs must include. Section 50.36(c) states in part, that TSs will include items in the following categories: (1) safety limits, limiting safety system settings, and limiting control settings; (2) limiting conditions for operation; (3) surveillance requirements; (4) design features; and (5) administrative controls.

The NRC provides guidance on the relocation of cycle-specific TS parameters to the COLR, to all power reactor licensees and applicants in NRC Generic Letter (GL) 88-16, Removal of Cycle-Specific Parameter Limits from Technical Specifications, (ML031200485). In GL 88-16, the NRC staff stated that license amendments are generally required every refueling outage to update the cycle-specific parameter limits in the TSs. However, there are methodologies developed for the licensee to determine these cycle-specific parameters that have been reviewed and approved by the NRC staff. As a result, the NRC staff review of proposed changes to the TSs to update these parameter limits is primarily limited to the confirmation that the updated limits were calculated by the approved methodology and consistent with the plant-specific safety analysis. The COLR was created to place the NRC-approved methodologies in the TSs and allow licensees to use these methodologies to update the parameters without requiring a change to the TSs.

The NRC staff approved Westinghouse Topical Report WCAP-14483-A, Generic Methodology for Expanded Core Operating Limits Report (ML020430092) as an acceptable method to relocate certain TS requirements to the COLR consistent with GL 88-16. The WCAP-14483-A addresses the relocation of the (1) reactor core safety limits figure (with corresponding revision to the safety limits), (2) Overtemperature T (Delta-T) and Overpower T (Delta-T) setpoint parameter values, and (3) departure from nucleate boiling (DNB) parameter limits for reactor coolant system (RCS) average temperature, RCS flow rate, and pressurizer pressure, to the COLR.

In TSTF-339, Revision 2, the NRC staff approved the incorporation of the TS changes identified in WCAP-14483-A into NUREG-1431, Volume 1, Revision 2, Standard Technical Specifications, Westinghouse Plants, June 2001 (ML011840223).

Technical Issue

SNC is proposing changes to TS 3.4.1, RCS Pressure, Temperature, and Flow Departure from Nucleate Boiling (DNB) Limits, to relocate reactor coolant system (RCS) DNB limits from the TS Limiting Conditions for Operation (LCO) and from Surveillance Requirements (SRs) to the COLR.

The NRC letter dated January 19, 1999, and titled Acceptance for Referencing of Licensing Topical Report WCAP-14483, Generic Methodology for Expanded Core Operating Limits Report (ML020430092) approved the COLR methodology that was incorporated in to TSTF-339, Revision 2. In the safety evaluation (SE) accompanying the letter dated January 19, 1999, RCS total flow rate was addressed with the exception that the total value for RCS flow also be retained in the TS.

The SE dated January 19, 1999, states: Although some plants operate with lower steam generator tube plugging levels and thus higher RCS flow rates than those assumed in the safety analyses, a change in RCS flow is an indication of a physical change to the plant which should be reviewed by the NRC staff. Because of this, the staff recommended that if the RCS flow rates were to be relocated to the COLR, the minimum limit for RCS total flow based on a staff approved analysis (e.g. maximum tube plugging) should be retained in the technical specifications to ensure that a lower flow rate than reviewed by the staff would not be used. The Westinghouse Owners Group concurred with this recommendation and modified the proposed technical specifications accordingly.

In the letter dated April 11, 2023, SNC described industry resolution of the historically high variance in steam generator tube plugging levels in the 1990s. The letter dated April 11, 2023, also noted that other TS administrative programs provide forward looking, performance-based, monitoring of steam generator tube plugging conditions to maintain conservatism in accordance with the approved analyses.

Generic Letter 88-16 allows for moving limits for reactor physics parameters that generally change with each reload core but is not intended for reactor physics parameters which remain unchanged on a cycle specific basis. With the steam generator tube plugging issues resolved, it is not clear to the NRC staff that the RCS total flow limit is expected to change on a cycle-to-cycle basis.

Request for Additional Information

RAI #6 Please provide a supplement which details recent changes to the RCS total flow parameter over the past reload seven cycles (approximately past 10 years) as well as any anticipated cycle to cycle changes in the RCS total flow rate parameters expected in the next 10 years. The changes can be described in a high-level summary and do not need to include any technical specifics that would constitute proprietary information. The summary only needs to confirm the cycle specific nature of the RCS total flow parameter in order to ensure that the limit is correctly applied in accordance with the guidance specified in GL 88-16.

Hearing Identifier: NRR_DRMA Email Number: 2225

Mail Envelope Properties (MN2PR09MB50842B1D0BF209BBE38D780FFAE8A)

Subject:

For Your Action - Request for Additional Information (RAI) #6 - Vogtle -

TSTF-339 LAR (L-2023-LLA-0053)

Sent Date: 9/5/2023 11:23:31 AM Received Date: 9/5/2023 11:23:00 AM From: John Lamb

Created By: John.Lamb@nrc.gov

Recipients:

"Chamberlain, Amy Christine" <ACCHAMBE@southernco.com>

Tracking Status: None "Pournaras, DeLisa S." <DSPOURNA@SOUTHERNCO.COM>

Tracking Status: None

Post Office: MN2PR09MB5084.namprd09.prod.outlook.com

Files Size Date & Time MESSAGE 8519 9/5/2023 11:23:00 AM

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