CNL-24-047, Decommitment of Flood Mode Mitigation Improvement Systems

Decommitment of Flood Mode Mitigation Improvement Systems

ML24268A308
Person / Time
Site:	Sequoyah, Watts Bar
Issue date:	09/24/2024
From:	Hulvey K Tennessee Valley Authority
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
CNL-24-047
Download: ML24268A308 (1)

Text

Tennessee Valley Authority, 1101 Market Street, Chattanooga, Tennessee 37402

CNL-24-047

September 24, 2024

10 CFR 50.4

ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001

Sequoyah Nuclear Plant, Units 1 and 2 Renewed Facility Operating License Nos. DPR-77 and DPR-79 NRC Docket Nos. 50-327 and 50-328

Watts Bar Nuclear Plant, Units 1 and 2 Facility Operating License Nos. NPF-90 and NPF-96 NRC Docket Nos. 50-390 and 50-391

Subject:

Decommitment of Flood Mode Mitigation Improvement Systems

References:

1. TVA Letter to NRC, Commitment to Install Improved Flood Mitigation Systems, dated April 16, 2013 (ML13108A107)

2. TVA Letter to NRC, CNL-22-070, Status Regarding the Improved Flood Mitigation System Project, dated June 30, 2022 (ML22181A343)

3. TVA Letter to NRC, CNL-19-066, Application to Revise Sequoyah Nuclear Plant Units 1 and 2 Updated Final Safety Analysis Report Regarding Changes to Hydrologic Analysis, (TS-19-02), dated January 14, 2020 (ML20016A396)

4. NRC Letter to TVA, Sequoyah Nuclear Plant, Units 1 and 2 - Issuance of Amendment Nos. 367 and 361 Regarding Changes to the Hydrologic Analyses (EPID L-2020-LLA-0004), dated March 26, 2024 (ML24040A206)

5. TVA Letter to NRC, CNL-23-005, Application to Revise Watts Bar Nuclear Plant Units 1 and 2 Updated Final Safety Analysis Report Regarding Changes to Hydrologic Analysis, (WBN-19-011), dated December 26, 2023 (ML24003A270)

By letter dated April 16, 2013, Tennessee Valley Authority (TVA) committed to install improved flood mitigation systems at the Sequoyah Nuclear Power Plant (SQN), Units 1 and 2, and the Watts Bar Nuclear Plant (WBN), Units 1 and 2 (Reference 1). TVA originally committed to complete implementation of the improved f lood mitigation systems at SQN and WBN by December 31, 2016. Subsequently, TVA informed the Nuclear Regulatory Commission (NRC) of changes in the specified field implementation completion schedule. The series of implementation schedule changes were based on the ongoing TVA project to upgrade precipitation models and rerun hydraulic models to determine new probable maximum flood U.S. Nuclear Regulatory Commission CNL-24-047 Page 2 September 24, 2024

levels for both design basis and beyond-design-basis purposes. In Reference 2, TVA had committed to implement the improved flood mitigation systems at SQN and WBN by September 30, 2024.

Since Reference 1 was submitted, a license amendment request (LAR) to incorporate an updated hydrologic analysis in the licensing basi s for SQN was submitted by letter dated January 14, 2020 (Reference 3) and was subsequently approved by the NRC in Reference 4.

A similar LAR was submitted for WBN in Reference 5 and is currently under NRC review.

TVA has concluded that the revised hydraulic modeling and the submittal of LARs associated with the updates to the SQN and WBN licensing bases have demonstrated appropriate design margins such that additional flood mitigating systems at SQN and WBN are no longer needed.

Therefore, TVA is decommitting from the last remaining commitment associated with the improved flood mitigation system project, as provided in Reference 2, to implement an improved flood mode mitigation system at SQN Units 1 and 2, and WBN Units 1 and 2 by September 30, 2024.

This letter removes one regulatory commitment and there are no new regulatory commitments contained in this letter. If additional information is needed regarding this letter, please contact Russell Thompson at rrthompson@tva.gov.

Respectfully,

Kimberly D. Hulvey General Manager, Nuclear Regulatory Affairs & Emergency Preparedness

cc:

NRR Director - NRC Headquarters NRC Regional Administrator - Region II NRC Project Manager - Sequoyah Nuclear Plant NRC Project Manager - Watts Bar Nuclear Plant NRC Senior Resident Inspector - Sequoyah Nuclear Plant NRC Senior Resident Inspector - Watts Bar Nuclear Plant