ML11353A319

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12/8/11 Meeting Slides - Brown Ferry Nuclear Plant, Units 1, 2, and 3 - Meeting with the Tennessee Valley Authority (TVA) to Discuss Delay in Submittal of Fire Risk Reduction Amendment Request
ML11353A319
Person / Time
Site: Browns Ferry  Tennessee Valley Authority icon.png
Issue date: 12/13/2011
From:
Tennessee Valley Authority
To:
Office of Nuclear Reactor Regulation
brown eva
References
Download: ML11353A319 (26)
v • d • e


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Ill] BFN Fire Risk Reduction and Nuclear NFPA 805 Transition

  • Robert Whalen Vice President, Nuclear Engineering
  • Keith Polson Vice President, Browns Ferry Nuclear Plant
  • Joseph Shea Corporate Manager, Nuclear Licensing
  • Brenda Simril Senior Manager, Fire Protection
  • Ching Guey Senior Manager, PRA

[i!lil BFN Fire Risk Reduction and Nuclear NFPA 805 Transition

  • Objectives:
  • Describe TVA Fleet Strategy for Fire Risk Reduction
  • Discuss Completed and Ongoing Fire Risk Reduction Modifications
  • Discuss the Status of NFPA 805 Transition Project Including:
  • Major Project Elements, Challenges and Milestones
  • Submittal Schedule 3

TVA Fleet Fire Risk Reduction Nuclear Strategy

  • Fleetwide Strategy

- Reduce reliance on operator manual actions (OMAs) in fire safe shutdown procedures

- Resolve Multiple Spurious Operation (MSO) issues

- Improve fire protection system material condition

  • Additional Site Specific Strategies

- BFN: Implement NFPA 805 Transition

- SQN and WBN: Develop Fire PRAs 4

TVA Fleet Fire Risk Reduction Nuclear Strategy - Browns Ferry Detail

- Eliminate high risk Self-Induced Station Blackout (SISBO) strategy

- Shift from "single success path" strategy

  • Modify the plant and procedures in parallel with development of NFPA 805 analysis and application Achieve significant reduction in fire risk earlier in near term Identify and implement near term or "pull forward" activities Example: Reanalysis of turbine building and intake pumping station safe shutdown strategies and implementation of interim 551 revisions
  • Drive the project to an aggressive schedule 5

Il!

Nuclear BFN Fire Protection Program

Background

  • Plant design and construction influenced historical approach to Appendix R compliance

- Shared electrical system

- Safe shutdown analysis was based on minimal systems and components

- Originally "'1400 time critical OMAs in 40 SSls 6

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Nuclear BFN Fire Protection Program Background - (Continued)

  • Safe shutdown analysis was developed to guarantee limited set of systems and components assuming a loss of offsite power (LOOP) occurred

- Self Induced Station Blackout (SISBO) Strategy

Risk Reduction Plant and Procedure Nuclear Modifications Operator Manual Action Reduction Efforts:

  • TVA prioritized reduction of OMAs in parallel to developing NFPA 805 transition plan
  • OMA resolution strategies included:

- Performing analysis changes for Time Critical OMAs

- Implementing feasible near term modifications 8

U!il Nuclear Risk Reduction Plant and Procedure Modifications Operator Manual Actions Changes Achieved to Date:

  • Eliminated 1V36 actions to open shop breaker at Battery Board 3

- Breaker made spare and required by procedure to remain open for Appendix R purposes

  • Eliminated 1V70 actions to start Unit 3 Diesel auxiliary transformer fans

- Analysis changed to credit automatic fans start

  • Revised 1V740 HVAC restoration actions from 60 min or 120 min to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> based upon new room heatup analyses

- Actions involve securing non-credited HVAC train and placing credited HVAC train in service 9

[i!] Risk Reduction Plant and Procedure Modifications Nuclear Reduction of Time-Critical OMAs <<60 Minutes):

- Note: Slight upward curve due to additional OMAs to mitigate Common Accident Signal logic issues (LER 50-259-2005-005)

Time Criticallll.G.2 OMAs 1600 1400 '"

1200 1000 ""

800 600 400

" ~ ----- - Time Criticallll.G.2 OMAs 200 o I I I I Mar-09 Sep-09 Sep-l0 11-Sep 10

Risk Reduction Plant Modifications and Nuclear Procedure Revisions Risk Reduction Modifications:

  • Installation of Incipient Detection in 250V Reactor Motor Operated Valve (RMOV) Board lA

- High Risk Ignition Source in Significance Determination Process (SOP)

- Status: Complete

  • Provided covers for cable trays to increase time to damage Installed solid bottom or top tray covers above Electrical Board Rooms for all 3 units, totaling ~100 ft of cable tray High Risk Areas in SOP

- Status: Complete 1

Risk Reduction Plant and Procedure Nuclear Modifications Risk Reduction Modifications (Continued):

  • Turbine Building and Intake Fire area Separation

- Subdivided large fire area into 4 smaller fire areas

- New 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> fire barrier

- New fire safe shutdown strategy and procedures

- Status: Complete

  • Installation of protective fusing for Shutdown Board 3EC

- Eliminates high risk OMA in SDP

- Status: Spring 2012 Unit 3 Refueling Outage 12

Risk Reduction Plant and Procedure Nuclear Modifications Turbine Building Fire Area Separation - Additional Detail:

  • New 3 Hour Barrier installed

- Separates Common Turbine Building from Intake Structure and Cable Tunnel

  • Revised Associated Safe Shutdown Analysis and SSls Used new shutdown strategies planned for NFPA 805 transition Eliminated SISBO actions Subdivided into 4 new fire areas Reduced time critical OMAs for fires in Turbine Building/Intake Area as shown in table below Previous 881s Revised 881s Procedure 88125-1 88125-11 88125-1 88125-2 88125-3 88126 Time 22 25 8 3 3 3 critical OMAs 13

Pull Forward Projects Risk Reduction TURBINE 00 00 BUILDING 00 FUEL OIL G

ELEV 565 0

'w'ATER HAT CH TANKS

£ EACTDR BUILDING L [GFND INTAKE PUMP

. '.l KOS[ STATIm MJLTJ -PURPOSE DRY STATION Al PORTABLE

~ 'IRE [lOOR INTAKE STRUCTURE CABLE TUNNEL BFN Fire Protection Risk Reduct ion and 12/06/2011 14 NFPA 80S Transition Status

1m Nuclear Risk Reduction Plant and Procedure Modifications Turbine Building Fire Area Separation:

New 3-hr rated fire barrier separating TB from Intake Pumping Station Tunnel 15

Risk Reduction Plant and Procedure Nuclear Modifications Safe Shutdown Instruction (SSI)Branching Step Revision:

  • Implemented procedure changes to all 40 551s to provide alternate pathway options

- Entry conditions remained unchanged

- Operator allowed to use alternate paths IF the original 551 path cannot be executed as written (such as due to component fault)

- Procedure revisions also included warnings for major systems/trains to avoid using for a fire on one unit which could adversely impact the other units

- 5tatus: Complete (April, 2011) 16

Extrapolated SDP Risk for Risk-Reduction Measures Nuclear (Trend Illustration Only)

Extrapolated SDP Risk for Various Risk-Reduction Measures 2.s0E-Os til Qj 2.00E-Os Qj Cl.

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LLJ s.00E-06 O.OOE+OO Pull-Incipient Provide *551 SDB Forward *551 SDP As Fire divisional Branching Revision protective I NFPA 80S Original Detection tray (Aug fusing Currently Step (Q2 (U3, Q2 Based 551 Value SDB protection 2011, FA Scoped 2011)

(Q12011) (Q12011) 25,26) 2012)

(Oct 2010)

-+- Extrapolated SDP Risk for Unit 1 2.29E-Os L8sE-Os L67E-Os L26E-Os 6.30E-06 s.68E-06 s.68E-06 LOOE-06

~ Extrapolated SDP Risk for Unit 2 2.13E-Os L8sE-Os L70E-Os 1.38E-Os 6.88E-06 6.49E-06 6.49E-06 LOOE-06

- I - Extrapolated SDP Risk for Unit 3 1.66E-Os L3sE-Os 1.33E-Os L12E-Os s .s8E-06 s.lsE-06 2.90E-06 LOOE-06

  • Assume 50% reduction of the SDP risk based on SSI revision which provides guidance on use of EOI and alternate flow path 17

[ml NFPA 805 Transition Project Status Nuclear Project Organization Overview

  • TVA Corporate engineering leadership role

- PRA and fire protection group greatly strengthened

  • Benchmarked industry for lessons learned to determine most effective project organization
  • Four separate contract firms selected based on specialized skills and knowledge of the NFPA 805 transition process
  • Detailed resourced and logic tied schedule in place to manage the project
  • Project has full resource support from TVA leadership 18

~ NFPA 805 Transition Project Status Nuclear Major Project Elements

- Inclusion of 11 additional systems

- "'1,600 components in Appendix R

- "'2,750 components for NFPA 805

- Inclusion of Offsite Power

- New shutdown strategies to utilize the additional systems

  • Circuit Analysis and Cable Routing for Additional SSA and PRA Components

- '" 5,550 cables in Appendix R

- '" 11,150 cables in NFPA 805

  • Revised SAFE Model for Separation Analysis

'" 13,000 cable- equipment logic relationships in Appendix R

- '" 29,000 cable- equipment logic relationships in NFPA 805 19

U!il Nuclear NFPA 805 Transition Project Status Major Project Elements (Continued)

  • Upgrade PRA to model plant response to fire damage
  • Modeling of Fire Scenarios

- "'3,000 fire scenarios

- Plant walkdowns to identify target cables

  • Fi re Area Assessments Establish shutdown method and credited train Determine Variances from Deterministic Requirements (VFDRs)

"'40 Fire Areas

  • Fire Risk Evaluations 20

NFPA 805 Transition Project Status Nuclear Project Challenges

  • Identification of Target Cables in Plant

- Extensive plant walkdown of Fire Zones of Influence (ZOls)

  • Initial Fire PRA Quantification

- Process requires multiple iterations

II!D Nuclear NFPA 805 Transition Project Status Major Project Milestones:

- Status: rv 80% complete

  • Circuit Analysis and Cable Routing

- Status: >90% complete

  • Upgrade SAFE Database Model

- Status: >90% complete

  • Fire PRA Peer Review / Completion of Fire PRA tasks

- In Progress - As discussed on Subsequent Slides 22

NFPA 805 Transition Project Status Nuclear Major Project Milestones (cont):

  • NSCA Fire Area Assessments

- In Progress

  • Fire Risk Evaluations (FREs) for variances from deterministic requirements (VFDRs) identified in Fire Area Assessments Industry standard is to perform this effort in series after completion of NSCA Fire Area Assessments TVA has developed a staggered approach to support aggressive project schedule
  • LAR preparation and submittal 23

U!il Nuclear NFPA 805 Transition Project Status Fire PRA Peer Review/Completion of Fire PRA Tasks

  • Recent assessment by ANS Fire Peer Review Standard Chair

- Assessment was element of project plan

- Outcome was decision to move the fire PRA Peer Review from week of October 24, 2011 to week of January 23, 2012

  • PRA quantification is in progress and on target for peer review
  • TVA team is participating in BWROG peer reviews and workshops to incorporate best practices from pilot plants and other NFPA 805 plants

- TVA understands that NRC approval would be required prior to crediting these methods 24

~

Nuclear NFPA 805 Transition Project Status

  • TVA is on track for January 2012 Fire PRA Peer Review

- Fire PRA Available for Potential Stand Alone Submittal - March 2012

  • TVA is committed to strategy of parallel plant modification and NFPA 805 application development

- Have identified additional plant modifications based on evolving Fire PRA

  • TVA updated projected schedule for submittal of complete NFPA 805 License Amendment Submittal

- First Quarter CY 2013 25

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