ML16175A518

Tennessee Valley Authority - Hydrologic Engineering Center River Analysis System (HEC-RAS) Project Milestones

ML16175A518
Person / Time
Site:	Browns Ferry, Watts Bar, Sequoyah
Issue date:	06/22/2016
From:	Shea J W Tennessee Valley Authority
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
CNL-16-083
Download: ML16175A518 (7)

Text

Tennessee Valley Authority, 1101 Market Street, Chattanooga, Tennessee 37402 CNL-16-083 June 22, 2016

10 CFR 50.4

ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Browns Ferry Nuclear Plant, Units 1, 2, and 3 Renewed Facility Operating License Nos. DPR-33, DPR-52, and DPR-68 NRC Docket Nos. 50-259, 50-260, and 50-296 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:

TENNESSEE VALLEY AUTHORITY - HYDROLOGIC ENGINEERING CENTER RIVER ANALYSIS SYSTEM (HEC-RAS) PROJECT MILESTONES During an April 4, 2016 public meeting to discuss technical details of the Tennessee Valley Authority (TVA) HEC-RAS external flood modelling issues, TVA agreed to provide the NRC with more definitive dates for several project deliverables, and to provide a copy of a letter sent from TVA to the United States Army Corps of Engineers (USACE) regarding some identified HEC-RAS model issues. The purpose of this letter is to provide that information.

TVA's presentation during the public meeting included a draft project milestone schedule.

Several project deliverables and associated submittals to NRC were discussed in detail. The draft schedule has been further developed and refined, resulting in the project deliverable milestones listed in Table 1 on the following page.

U.S. Nuclear Regulatory Commission CNL-16-083 Page 2 June 22, 2016

TABLE 1 PROJECT DELIVERABLE SUBMITTAL MILESTONES Project Deliverable Submittal Milestone 1 Browns Ferry Mitigating Strategies Assessment (MSA) December 2016 2 Sequoyah MSA December 2016 3 Watts Bar MSA December 2016 4 Watts Bar Focused Evaluation (FE)

• December 2017

• 5 Sequoyah FE

• December 2017

• 6 Browns Ferry FE

• December 2017

• 7 Sequoyah Hydrology License Amendment Request (LAR) April 2018 8 Watts Bar Hydrology LAR May 2018

• It is TVA's plan to perform Focused Evaluations for each site in lieu of Integrated Assessments. These deliverables and dates represent revised commitments from those made in the letters dated March 12, 2015, which transmitted the Browns Ferry, Sequoyah, and Watts Bar Flood Hazard Reevaluation Reports (ML15072A130, ML15071A462, and ML15071A262), respectively. Formal revision of these commitments will be the subject of separate correspondence after the revised guidance for performing integrated assessments and more focused evaluations are issued. TVA will submit status updates on these project deliverable submittal milestones to the NRC on a six-month frequency. The first status update will be submitted no later than December 31, 2016.

As discussed in the referenced public meeting, the ongoing HEC-RAS external flood modeling utilizes updated precipitation input data from that currently described in the Browns Ferry, Sequoyah, and Watts Bar Updated Final Safety Analysis Reports. The TVA calculation that documents this updated precipitation data has been completed and issued.

As the precipitation input is a fundamental component of the overall external flood modeling, the associated calculation will be a key reference supporting the Sequoyah and Watts Bar LARs listed above.

CNL-16-083 ENCLOSURE 1 TVA LETTER TO U.S. ARMY CORPS OF ENGINEERS

CNL-16-083 ENCLOSURE 2 COMMITMENT 1. TVA will submit status updates on the HEC-RAS project deliverable submittal milestones to the NRC on a six-month frequency. The first status update will be submitted no later than December 31, 2016.