Text

Slides, Internal Flooding Risk Reduction Activities, from Kewaunee Regulatory Public Meeting
	ML063460495
Person / Time
Site:	Kewaunee
Issue date:	11/30/2006
From:	; Dominion
To:	; Office of Nuclear Reactor Regulation
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	Download: ML063460495 (32)
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Introduction Leslie Hartz Site Vice President

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

Internal Flooding Background Lori Armstrong Director Engineering

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

Additional Flood Barriers

Barrier between Turbine Building and

Safeguards Alley Flood Level 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

Pre-modification Circulating Water Outlet Expansion Joints

Post-modification Circulating Water Outlet Expansion Joint

Risk Profile and Safety Improvements Tom Hook Supervisor PRA

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 4.0E-04 3.0E-04 2.0E-04 1.0E-04 0.0E+00 Auxiliary Turbine Safeguards Internal Building Building Alley Flooding Initiating Flooding Flooding Events

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

Installed circulating water pump trip on high turbine building level

Reduced CDF by 4.1E-4/yr Model improvements

Upgraded flooding models for Auxiliary Bldg and Safeguards Alley to address WOG peer review comments

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 4.0E-04 3.0E-04 2.0E-04 1.0E-04 0.0E+00 Auxiliary Turbine Safeguards Internal Building Building Alley Flooding Initiating Flooding Flooding Events

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

Included procedure changes enhancing service water isolation

Reduced CDF by 1.3E-4/yr

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

Current Dominant CDF Initiators 4.0E-05 3.0E-05 2.0E-05 1.0E-05 0.0E+00 SW A Fl ood SW B Spr ay RWST f l ood SW B Spr ay SW B Fl ood SW B Spr ay Tr ansi ent Loss of Steam Loss of i n Aux Bl dg on Tr ai n A i n Aux Bl dg i n Aux Bl dg i n Aux Bl dg on Tr ai n A wi th MFW Component Gener ator Of f si te 480V Swgr Basement EDG/ 4kV Avai l abl e Cool i ng Tube Power Swgr Ruptur e Note: SW pipe is seismically qualified.

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

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

Impact of Modifications on Dominant CDF Initiators 4.0E-05 Current Post-Modification 3.0E-05 2.0E-05 1.0E-05 0.0E+00 SW A Flood in SW B Spray RWST f lood SW B Spray SW B Flood in SW B Spray Transient Loss of St eam Loss of Aux Bldg on Train A in Aux Bldg in Aux Bldg Aux Bldg on Train A wit h MFW Component Generat or Of f sit e 480V Swgr Basement EDG/ 4kV Available Cooling Tube Power Swgr Rupt ure Note: SW pipe is seismically qualified.

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

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

Modifications Lori Armstrong Director Engineering

Installation of Watertight Door Scope:

Installation of a watertight door between Aux Building and Safeguards Alley Proposed Schedule:

Door installation during next refueling outage

Installation of Aux Building Water Level Alarms Scope:

Addition of Auxiliary Building water level alarms Proposed Schedule:

Installation of level indication 2Q07

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

Install Spray Shields on SW piping Scope:

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

1Q08

Summary 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

Questions

ML063460495

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