ML063460495

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Slides, Internal Flooding Risk Reduction Activities, from Kewaunee Regulatory Public Meeting
ML063460495
Person / Time
Site: Kewaunee Dominion icon.png
Issue date: 11/30/2006
From:
Dominion
To:
Office of Nuclear Reactor Regulation
References
Download: ML063460495 (32)
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Text

© Dominion 2006

© 2006 Dominion Regulatory Meeting Internal Flooding Risk Reduction Activities November 30, 2006

© Dominion 2006

© 2003 Dominion 3

Introduction Leslie Hartz Site Vice President

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© 2003 Dominion 4

AGENDA Introduction Leslie Hartz - Site VP

Background

Lori Armstrong - Director Engineering PRA History Tom Hook - Supv. PRA Modifications Lori Armstrong - Director Engineering Conclusion Leslie Hartz - Site VP

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© Dominion 2006 Internal Flooding Background Lori Armstrong Director Engineering

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© Dominion 2006

Background

Since 2004 numerous modifications installed reduce risk from Internal Flooding

  • Spring 2005 - Turbine Building Flooding Barrier installation
  • Fall 2005 - Safeguards Alley Level Alarms
  • 2006 - Procedure changes and outage maintenance

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© Dominion 2006 Additional Flood Barriers

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© Dominion 2006 Barrier to Safeguards Alley

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Barrier between Turbine Building and the far end of Safeguards Alley

© 2003 Dominion 10 Level Switch Circulating Pump Trip

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© Dominion 2006 Safeguards Alley Flood Level Safeguards Alley Flood Level Indication Indication Level switches and alarms for:

A AFW pump room B AFW pump room DG A room DG B room Bus 51/52 room Bus 61/62 room TD AFW pump room Cardox room

© 2003 Dominion 12 Pre-modification Circulating Water Outlet Expansion Joints

© 2003 Dominion 13 Post-modification Circulating Water Outlet Expansion Joint

© 2003 Dominion 14

© Dominion 2006 Risk Profile and Safety Improvements Tom Hook Supervisor PRA

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© Dominion 2006 Flood Risk Contribution as of 12/2004 CDF = 7.2E-04/yr (internal events plus flooding) 95% of total CDF from flooding sequences Dominant CDF Contributors 0.0E+00 1.0E-04 2.0E-04 3.0E-04 4.0E-04 Auxiliary Building Flooding Turbine Building Flooding Safeguards Alley Flooding Internal Initiating Events

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© Dominion 2006 PRA Modifications Completed in 2005 Incorporated plant modifications

  • Installed flood barriers between Turbine Building and Safeguards Alley
  • Installed flood sensors and alarms in Safeguards Alley
  • Reduced CDF by 4.1E-4/yr Model improvements
  • Upgraded flooding models for Auxiliary Bldg and Safeguards Alley to address WOG peer review comments

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© Dominion 2006 Flood Risk Contribution as of 12/2005 CDF = 3.1E-04/yr (internal events plus flooding) 92% of total CDF from flooding sequences Dominant CDF Contributors 0.0E+00 1.0E-04 2.0E-04 3.0E-04 4.0E-04 Auxiliary Building Flooding Turbine Building Flooding Safeguards Alley Flooding Internal Initiating Events

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© Dominion 2006 PRA Modifications Completed in 2006 Incorporated procedure changes

  • Included new operator actions to address loss of battery room, AFW pump room or safeguards bus ventilation during safeguards flooding
  • Reduced CDF by 1.3E-4/yr

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© Dominion 2006 Flooding Risk Contribution - Current Dominant CDF Contributors 0.0E+00 1.0E-04 2.0E-04 3.0E-04 4.0E-04 Auxiliary Building Flooding Turbine Building Flooding Safeguards Alley Flooding Internal Initiating Events CDF = 1.8E-04/yr (internal events plus flooding) 82% of total CDF from flooding sequences

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© Dominion 2006 Current Dominant CDF Initiators Note: SW pipe is seismically qualified.

0.0E+00 1.0E-05 2.0E-05 3.0E-05 4.0E-05 SW A Flood in Aux Bldg SW B Spr ay on Tr ain A 480V Swgr RWST f lood in Aux Bldg SW B Spr ay in Aux Bldg Basement SW B Flood in Aux Bldg SW B Spr ay on Tr ain A EDG/ 4kV Swgr Tr ansient with MFW Available Loss of Component Cooling Steam Gener ator Tube Ruptur e Loss of Of f site Power

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© Dominion 2006 Near Term Risk Reduction Actions z Install watertight door between Auxiliary Building and Safeguards Alley z Install flood level alarms in Auxiliary Building z Relocate risk significant bottom row breakers 15206 and 16206 on 480V buses to spare higher locations z Install spray shields around service water piping in Safeguards Alley to protect 480V and 4kV switchgear from spray

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© Dominion 2006 Plant Risk After Proposed Modifications CDF = 6.2E-05/yr 50% of total CDF from flooding sequences Dominant CDF Contributors 0.0E+00 1.0E-04 2.0E-04 3.0E-04 4.0E-04 Auxiliary Building Flooding Turbine Building Flooding Safeguards Alley Flooding Internal Initiating Events

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© Dominion 2006 Impact of Modifications on Dominant CDF Initiators Note: SW pipe is seismically qualified.

0.0E+00 1.0E-05 2.0E-05 3.0E-05 4.0E-05 SW A Flood in Aux Bldg SW B Spray on Train A 480V Swgr RWST flood in Aux Bldg SW B Spray in Aux Bldg Basement SW B Flood in Aux Bldg SW B Spray on Train A EDG/4kV Swgr Transient with MFW Available Loss of Component Cooling Steam Generator Tube Rupture Loss of Offsite Power Current Post-Modification

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© Dominion 2006 1.0E-05 1.0E-04 1.0E-03 12/2004 12/2005 Current 5/2008 Date Core Damage Frequency Internal Events Risk Profile since 2004

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© Dominion 2006 Summary Dominion committed to reduce internal flooding risk at Kewaunee zWith proposed modifications, CDF will be reduced by 91% to 6.2E-5/yr zInternal flood contribution after proposed modifications will be 50% of internal events CDF

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© Dominion 2006 Modifications Lori Armstrong Director Engineering

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© Dominion 2006 Installation of Watertight Door Scope:

  • Installation of a watertight door between Aux Building and Safeguards Alley Proposed Schedule:
  • Door installation during next refueling outage

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© Dominion 2006 Installation of Aux Building Water Level Alarms Scope:

  • Addition of Auxiliary Building water level alarms Proposed Schedule:
  • Installation of level indication 2Q07

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© Dominion 2006 Raise breakers on 480V buses 52 and 62 Scope:

  • Relocate risk significant Class 1E breakers 15206, 16206 from bottom row to higher spare locations Proposed Schedule:
  • 4Q07

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© Dominion 2006 Install Spray Shields on SW piping Scope:

  • Install spray shields around service water piping in Safeguards Alley Proposed Schedule:
  • 1Q08

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© Dominion 2006 Dominion continues to reduce internal flooding risk at Kewaunee

  • With proposed modifications, CDF will be reduced by 91% since 2004 Dominion will continue to evaluate CDF reductions at Kewaunee Summary

© 2003 Dominion 32

© Dominion 2006 Questions

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