ML13189A135

Progress Update on Improved Flood Mitigation System Project

ML13189A135
Person / Time
Site:	Watts Bar, Sequoyah
Issue date:	07/01/2013
From:	James Shea Tennessee Valley Authority
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML13189A135 (21)

Text

Tennessee Valley Authority, 1101 Market Street, Chattanooga, Tennessee 37402 July 1, 2013 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 Facility Operating Licenses Nos. DPR-77 and DPR-79 NRC Docket Nos. 50-327 and 50-328 Watts Bar Nuclear Plant, Unit 1 Facility Operating License No. NPF-90 NRC Docket No. 50-390 Watts Bar Nuclear Plant, Unit 2 Construction Permit No. CPPR-92 NRC Docket No. 50-391

Subject:

Progress Update on Improved Flood. Mitigation System Project

References:

1. TVA letter, "Commitment to Install Improved Flood Mitigation Systems," dated April 16, 2013

2. TVA letter, "Tennessee Valley Authority (TVA) - Overall Integrated Plan in Response to the March 12, 2012, Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order EA-1 2-049) for Watts Bar Nuclear Plant," dated February 28, 2013

3. NRC letter, "Sequoyah Nuclear Plant - Final Significant Determination of White Findings, Notices of Violations, and Assessment Follow-up Letter:

Inspection Report No. 05000327/2013011, 05000328/2013011," dated June 4, 2013

4. NRC letter, "Watts Bar Unit 1 Nuclear Plant - Final Significant Determination of Yellow Finding, White Finding and notices of Violations: Assessment Follow-up Letter; Inspection Report No. 05000390/2013009," dated June 4, 2013 Printed on recycled paper R. f"

U.S. Nuclear Regulatory Commission Page 2 July 1, 2013 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 committed to complete implementation of the improved flood mitigation systems at SQN and WBN by December 31, 2016. TVA also committed to provide periodic written updates regarding progress of the project beginning with the first written progress report by June 30, 2013.

The purpose of this letter is to provide the first written report regarding progress of the improved flood mitigation system project consistent with Commitment 2 in Enclosure 2 of the April 16, 2013 letter. Since June 30, 2013 fell on a Sunday, TVA considered July 1, 2013 as the due date for this progress report.

During a public meeting on June 27, 2013, TVA briefed the NRC regarding the status of the improved flood mitigation project. The briefing material presented by TVA during the meeting is provided as Enclosure 1 to this letter. During the meeting, TVA advised the NRC that engineering design and project controls for the project are being developed consistent with TVA's existing design and project management procedures. Through the use of these design and project controls, TVA will provide for appropriate consideration of design alternatives while assuring design rigor and schedule adherence.

TVA noted that since issuance of the April 16, 2013 letter, potential design alternatives had emerged for a number of elements of the overall flood mitigation system design as described in Enclosure 1 of that letter. TVA provided examples of how alternatives were being considered for the design of the structure that will house key components in the flood mitigation system, for the design of the power source for the system and for the design of the method by which reactor decay heat will be removed during flood scenarios. TVA indicated that the following key elements of the April 16, 2013 letter will remain fixed as the system design evolves through the design process:

1. Final implementation date for the improved flood mitigation system at WBN and SQN by December 31, 2016. However, consistent with the consideration of alternative design options, the date for interim milestones discussed in Enclosure 1 of Reference 1 may change. Specific design alternatives and interim milestones will be discussed as part of the periodic updates discussed in Commitment 2 of Reference 1.

2. Installation of newly designed means for removing reactor decay heat and providing reactor coolant system makeup and criticality control, including protected sources of power, that are in addition to the existing licensing basis flood mode systems; and

3. Assurance that the improved flood mode system's key functions will be protected from flood levels no less than fifteen feet above existing design and licensing basis probable maximum flood levels. (TVA noted that reference to current licensing basis probable maximum flood levels were those described in TVA's license amendment applications dated July 19 and August 10, 2012 for WBN Unit 1 and SQN respectively.)

U.S. Nuclear Regulatory Commission Page 3 July 1, 2013 During the meeting, TVA noted that for WBN, one consideration for an alternative to the design of the structure to house key components of the flood mitigation system was to reduce the potential impacts and risks to the schedule for implementing the strategies described in TVA's February 28, 2013 submittal associated with compliance with NRC Order EA-12-049, "Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Effective Immediately)," (Reference 2). TVA noted that this was especially critical for assuring compliance with commitments in the February 28, 2013 letter for the WBN site. During the meeting, TVA also revised the commitment to Commitment 3 from Reference 1 to provide an updated strategy for the FLEX equipment storage building by June 30, 2013. An update to the strategy for WBN FLEX equipment storage will be provided by July 15, 2013.

Finally, during the June 27, 2013 meeting, TVA confirmed that the improved flood mitigation system is intended to improve protection against beyond design basis floods and is not required for compliance with the current licensing basis and that it is not a corrective action associated with the violations of NRC requirements described in NRC's letters to TVA dated June 4, 2013 (References 3 and 4).

TVA will provide the second quarterly written update of the status of the improved flood mitigation system project by September 30, 2013 consistent with Commitment 2 in Enclosure 2 of TVA's letter to NRC dated April 16, 2013.

There are two revised commitments contained in this letter as described in Enclosure 2.

If you have questions regarding this update, please contact Kevin Casey at (423) 751-8523.

Resp Ily, Shea President, Nuclear Licensing

Enclosures:

1. Slides for TVA's 1st Quarterly Update for the Improved Flood Mitigation System, June 27, 2013

2. Revised Commitments from April 16, 2013 cc: See Page 4

U.S. Nuclear Regulatory Commission Page 4 July 1, 2013 cc (w/Enclosures):

NRC Regional Administrator - Region II NRR Director - NRC Headquarters NRC Senior Resident Inspector - Sequoyah Nuclear Plant NRC Senior Resident Inspector - Watts Bar Nuclear Plant NRR Project Manager - Sequoyah Nuclear Plant NRR Project Manager - Watts Bar Nuclear Plant, Unit 1 NRR Project Manager - Watts Bar Nuclear Plant, Unit 2

ENCLOSURE 1 SLIDES FROM TVA'S 1st QUARTERLY UPDATE for the IMPROVED FLOOD MITIGATION SYSTEM JUNE 27, 2013

Seauoyah and Watts Bar NuclearPlants Ist QuarterlyUpdate for the Improved Flood Mitigation System June 27, 2013

[MAgenda Joe Shea, Vice President Introduction Nuclear Licensing Joe Shea Improved Flood Mitigation System Update Andrea Sterdis, General Manager Project Management Neil Gannon, General Manager Fukushima Response Project Closing Remarks Joe Shea TVA Nuclear Power Group 2

Improved Flood Mitigation System Update SQN and WBN Improved Flood Mitigation System r- Introduction Commitment to Improved Flood Mitigation Systems

• TVA Commitment Submitted in Letter dated April 16, 201-3:

• Implement an improved flood mitigation system at SQN Units 1 and 2 and WBN Units 1 and 2 by December 31, 2016

" Provide periodic written updates regarding progress of the project by the last day of March, June, September and December of each year until the project is completed, beginning with the first written progress report to be by filed by June 30, 2013.

" Submit an updated strategy for FLEX equipment storage at WBN Units 1 and 2 on or before June 30, 2013.

TVA Nuclear Power Group 4

SQN and WBN Improved Flood Mitigation System SIntroduction Commitment to Improved Flood Mitigation Systems

• Key Safety and Regulatory Aspects of Flood Mitigation System Commitment:

• Provide Additional Margin and Improve Protection Against Flood Hazards

• System Is In Addition to TVA Design and Strategy for Responding to Beyond Design Basis Events (FLEX)

- Flood Mitigation System Design M_. Leverage Elements of FLEX Strategy

• System is Not Required for Compliance with Current Licensing Basis for Flood Protection

- Current Licensing Basis for Flood Protection Is Adequate TVA Nuclear Power Group 5

SQN and WBN Improved Flood Mitigation System SIntroduction Commitment to Improved Flood Mitigation Systems

• Key Design Functions and Features in April 16, 2013 Commitment Letter:

• Improved Decay Heat Removal During Flood Mode

• Additional Reactor Coolant System Makeup and Criticality Control Capability During Flood Mode

• Provide Protection for Flood Mitigation System With No Less Than Fifteen Feet Margin Above Current Probable Maximum Flood Levels

- Protection for Power Supplies Protection for New Decay Heat Removal and RCS Makeup Capability

- Provide Clean Water Supply

- Develop Maintenance and Testing Capability TVA Nuclear Power Group 6

SQN and WBN Improved Flood Mitigation System SIntroduction Commitment to Improved Flood Mitigation Systems

• Transition from Commitment into Design and Construction Process:

" April 16, 2013 Commitment Informed by Conceptual Engineering Approach

- Sufficiently Informed to Make December 2016 Schedule Commitments

" Fulfillment of Commitment Will Be Assured Through TVA Project Controls and Engineering Design Process

- Engineering Design and Project Controls Process Provide for Rigorous Evaluation of Final Design Prior to Start of Construction

- Some Design Aspects Will Evolve From Conceptual Design

- Key Design Functions and Features Will Remain Unchanged TVA Nuclear Power Group 7

SQN and WBN Improved Flood MitigationSystem

~-Introduction Commitment to Improved Flood Mitigation Systems

• Key Concepts That May Evolve Through Application of Engineering Design and Project Controls Process:

-Design of Hardened Structure

• Use of Flood Elevated FLEX Equipment Storage Building vs.

Design of Stand Alone Flood Mitigation System Building

• Final Decision on Building Design Will Include Consideration of Impacts on Compliance Schedule for FLEX Mitigation Order e Final Decision on Building Design Will Ensure Minimum of Fifteen Feet of Margin Above Current PMF Levels e Final Building Decision Will Include Consideration of Risk Improvements for Scenarios Other Than Flooding TVA Nuclear Power Group 8

SQN and WBN Improved Flood Mitigation System SIntroduction Commitment to Improved Flood Mitigation Systems

• Key Concepts That May Evolve Through Application of Engineering Design and Project Controls Process (Continued):

- Power Source for Flood Mitigation System

" April 16, 2013 Commitment Letter Discussed FLEX 3MW Diesel Generators

" Subsequent Additional Engineering Assessment Indicates that 3MW DGs May Be Too Lightly Loaded During Flood Mitigation System Operation

- Resolution of DG Loading Challenges May Warrant Consideration of Additional Protected DGs Dedicated to Flood Mitigation System TVA Nuclear Power Group 9

SQN and WBN Improved Flood Mitigation System SIntroduction Commitment to Improved Flood Mitigation Systems

• Key Concepts That May Evolve Through Application of Engineering Design and Project Controls Process (Continued):

- Decay Heat Removal

• April 16, 2013 Commitment Letter Discussed Condensate Recovery System

• Subsequent Additional Engineering Assessment Indicated Potential Reliability Challenges

- Resolution of Decay Heat Removal Condensate Recovery Challenges May Warrant Consideration of Large Protected Clean Water Source in Once-Through Process TVA Nuclear Power Group 10

SQN and WBN Improved Flood MitigationSystem SIntroduction Commitment to Improved Flood Mitigation Systems

" Description of Project Controls Process (Subsequent Slides)

" Includes Key Project Milestones and Current Schedule

• Will Form Basis for Future Updates to NRC On Progress

" Update and Status on April 16, 2013 Progress Report Commitments

- June 30, 2013 Written Progress Report

- June 30, 2013 Updated Strategy on Watts Bar Unit 1 and 2 FLEX Equipment Storage

• Submit by July 15

• Reaffirm Commitment to Watts Bar FLEX Strategy and Schedule

• Changes to Watts Bar FLEX Equipment Storage Will Be Included in Periodic Required FLEX Updates TVA Nuclear Power Group 11

[M] SQN Project and WBN Improved Flood Mitigation System Management and Design Process IProI~Iijec TVA Nuclear Power Group 12

i*ProcueentMaaeetadDsgPrcs Phaseb Imle etai onJ Phase=

Syte Turnover,

• p,,-l J: n Closure,'

mula TVA PoeTrop 1

SQN and WBN Improved Flood MitigationSystem SProject Status - PreliminarySchedule Scedle Scheduled*

2 DeveloD Proiect Plan 06/01/13 09/30/13 In-proa ress 4 Perform Preliminary Design Phase 10/01/13 02/27/14 Not Started 6 Procure Long-Lead Items 11/01/13 I.E1 01/29/15 O w N1 S7b9 ET Not Started I pe ent: i@ I Txww 0 1 (Sta arim 8 Project Closeout 12/16/16 09/30/17 Not Started TVA Nuclear Power Group 14

Closing Remarks ENCLOSURE 2 Revised Commitments from April 16, 2013 Letter The commitments below supersede Commitments 1 and 3 from TVA's letter date April 16, 2013.

Commitment 2 from the April 16, 2013 letter remains unchanged.

1. TVA will implement an improved flood mitigation system at SQN Units 1 and 2 and WBN Units 1 and 2 by December 31, 2016. Interim milestones will be developed through TVA's engineering design and project controls processes and will be discussed as part of the periodic written progress updates discussed in Commitment 2.

3. TVA will submit an updated strategy for FLEX equipment storage at WBN Units 1 and 2 on or before July 15, 2013.