ML031690214

Enclosure 1- NMC Handout Regulatory Conference Concerning Auxiliary Feedwater Orifice Issue for 06/06/2003 Point Beach Regulatory Conference

ML031690214
Person / Time
Site:	Point Beach
Issue date:	06/16/2003
From:	Nuclear Management Co
To:	Office of Nuclear Reactor Regulation
References
Download: ML031690214 (36)

Text

Point Beach Nuclear Plant Regulatory Conference Concerning Auxiliary Feedwater Orifice Issue June 6, 2003 1

Agenda Purpose/Objective Mano Nazar Overview Fred Cayia Root Cause Analyses Fred Cayia Significance Mark Reddemann Determination Closing Remarks Mano Nazar 2

Purpose

Ø Provide Overview of Auxiliary Feedwater System Orifice Issue

Ø Discuss Root Cause Evaluation of the AFW Orifice Issue

Ø Present Methodology and Conclusion of the NMC/Point Beach Significance Determination Process for AFW Orifice Issue 3

Objective

Ø Present New Information and Considerations Concerning Issue Significance

Ø Provide NMCs Position on the Characterization of the Apparent Violation of 10 CFR 50, Appendix B, Criterion III Design Control 4

Overview 5

Overview Auxiliary Feedwater System U N IT 1 C O N T A IN M E N T M S E R V IC E W A T E R STEAM 1 MOV GENERATOR 4006 M A IN FEED 1 -1 1 1 1 -2 6 1 W ATER LO B 1 -1 0 1 T H R O T T LE D 1P29 DC-D C -B 1 -1 0 8 A M S T E A M D R IV E N M DC-A U X IL IA R Y F E E D M A IN S T E A M M A PUMP 1 -1 9 1 -1 0 7 1M O V 1 MOV DC-L 4000 FC 2019 B O 1 MS M 1 R O -4 0 0 3 1 -L44 1 -1 0 4 2082 M A IN STEAM O CST 1 MOV STEAM GENERATOR 1 A O V -4 0 0 2 2020 M A IN FEED MOV M FO M S e is m ic 4021 1 W ATER S E R V IC E W A T E R C la s s MOV 1 4 5 ,0 0 0 A 4016 1 -1 0 0 T H R O T T LE D CV 110 G A LLO N D C -A 4019 P38B M MOV 4020 M

52 CS TANK 113 LO 1 -L1 8 1 -1 0 6 1 MOV E L E C T R IC A U X IL IA R Y O 4001 FEED PUMP FC 1 -L3 1 1-102 R O -4 0 1 5 O

CST STEAM A O V -4 0 1 4 F ire W a te r C o n n GENERATOR M A IN (4 to ta l)

MOV M FEED M FO 4023 2 W ATER S E R V IC E MOV W ATER B 2 -1 0 1 CV 4009 D C -B T H R O T T LE D 109 M 4012 P38A MOV M 4022 112 39 2 -L5 7 2 LO 2 -1 0 7 E L E C T R IC A U X IL IA R Y MOV O 4000 FEED PUMP 2 -L4 5 2 -1 0 5 FC STEAM O GENERATOR M A IN R O -4 0 0 8 4 5 ,0 0 0 FEED CST G A LLO N A O V -4007 2 W ATER CS TANK A M 2 -1 0 0 T H R O T T LE D D C -A S E R V IC E M

2 MOV W ATER 4006 2 -L5 6 2 -1 0 6 2 MOV S e is m ic N O T E : A ll la b e le d v a lv e s O 4001 C la s s a r e A F - S y s te m v a lv e s ,

2 -1 1 1 2 -6 4 DC-LO e x c e p t a s n o te d 2 -L3 2 2 -1 0 3 M A 1 U N IT 2 C O N T A IN M E N T O 2P 29 DC- M A IN S T E A M R e fe r e n c e M - 2 1 7 S h . 1 & 2 2 -1 0 8 M B 2 MOV S T E A M D R IV E N DC-A U X IL IA R Y F E E D 2019 F O R IN F O R M A T IO N FC PUMP 2 MS M B M A IN S T E A M O NLY 2 R O -4 0 0 3 CST 2082 2 MOV 2020 2 A O V -4 0 0 2

Overview Timeline of AFW System Improvements July 1997 Missile Sept 2002 April 1993 protected AFW portions of Jan 2002 recirculation Feb. 1981 Sept 1986 Installed air line GL 81-14 issued Added SR EQ level to allow IST AFW suction NRC designated (AFW seismic transmitters for CST testing of AFW piping inspection of safety qualifications) (TMI response) recirculation Modifications function valves /50.59 May 1982 NRC SER, 1991 July 1997 Feb. 2002 NUREG-0737 Aug 1984 Added recirc flow Added AFW Added Oct 1970 Item II.E.1.2, Added AFW instruments and discharge valve backup U1 Licensed NRC accepts discharge larger recirc lines and backup nitrogen N2/air to March 1979 safety grade MOV controls orifices to increase supply; installed all AFW March 1973 TMI status of AFW (TMI recirc flow to 70 & cable separation recirc U2 Licensed Accident auto initiation response) 100 GPM modifications valves 1970 1980 1985 1990 1995 2000 March 2003 July 1981 Proper 1985 (larger)

Note: At time of licensing, Added AFW supply Feb 1998 Added low suction orifices AFW was not safety related line flow indication Upgraded pressure trip installed on (TMI response) AFW low (TMI response- all AFW suction seismic/ tornado) recirc lines June 1988 pressure trip Point Beach response Nov 1983 to IEB 88-04 March 1999 Added AFW (review of AFW Nov 1995 Modification to inoperable alarm minimum flow) Added SW flush assure control (TMI response) identifies need for connection at AFW wire separation greater recirculation pump suctions for AFW system flow capability 7

Overview Recirculation Line Orifice Discussion:

Ø Orifice Modification Developed in 2000 to Reduce Recirculation Line Cavitation

Ø Recirculation Line Orifices- Modification History Pump A Pump B Motor Driven AFW Pumps (MDAFP) June 2000 June 2000 Modification issued MDAFP Modification Installed November November 2000 2000 Unit 1 Unit 2 Turbine Driven Auxiliary Feedwater Pump March 2002 December (TDAFP) Modification Issued 2001 TDAFP Modification Installed October May 2002 2002 8

Overview Recirculation Line Orifice

==

Description:==

Potential for Fouling of Recirculation Line Coincident with Procedurally-Directed Operator Action to Secure AFW Forward Flow.

Ø Identified by NMC Following System Testing of the Motor Driven AFW Pump

Ø Orifice Plugging Could Occur When AFW Pumps Were Aligned to Service Water Resulting in Potential Common Mode Failure

Ø Prompt Corrective Actions

• All Four AFW Pumps Declared Out-of-Service Due to Potential Recirculation Orifice Common Mode Failure

• Compensatory Actions Established to Direct Operators to Secure AFW Pumps in the Event Minimum Recirculation Flow Cannot be Maintained 9

Root Cause Analyses 10

Root Cause Analyses AFW Recirculation Orifice

Ø Root Cause-Orifice Issue (RCE000191)

• Failure to Properly Evaluate the Potential for Orifice Plugging Within the Design Process

Ø Contributing Causes

• Use of Unverified Information and the Omission of Key Design Information in the Safety Evaluation for the Orifice Modification 11

Root Cause Analyses AFW Recirculation Orifice

Ø Corrective Actions- Complete

• Increased Engineering Management Involvement in Approval and Oversight of Modifications

• Implemented Periodic Review of Engineering Products by a Quality Review Team

• Presented Lessons Learned to Engineering Personnel Stressing the Use of the Design Process

• Revised Training Materials to Accurately Reflect AFW Recirculation Line Design Functions

• Orifice Redesigned, Tested and Installed on all Four Pumps in March 2003 12

Root Cause Analyses AFW Air Operated Valve Finding Missed Opportunity (RCE 01-069)

Ø The Root Cause Problem Statement Focused on Emergency Operating Procedure (EOP) Limitations Related to a Loss of Instrument air event.

Ø The Root Cause Problem Statement should have Focused on the Potential Loss of Recirculation Flow.

Ø The Extent of Condition Evaluation would then have Investigated Conditions in Addition to a Failed Closed AFW AOV recirculation valve.

Ø Examples of Possible Loss of Recirculation Failures would have Included:

§ Orifice Plugging

§ Electrical/ Control System Failures

§ Indication Failures 13

Root Cause Analyses Comprehensive AFW Evaluation

Ø Root Cause-Comprehensive AFW Evaluation (RCE000202)

• Failure to Consider the Integration of AFW System Design and Accident Progression (RC-1)

• Less than Adequate Knowledge of the Safety Significance of the AFW Recirculation Line in Protecting the Pumps (RC-2)

Ø Contributing Causes

• Lack of Problem and Issue Ownership (CC-1)

• Corrective Action Program Weaknesses

• Less than Adequate Engineering / Operations Interface (CC-2)

• Less than Adequate Management of the Inter-Relationship of Documents (CC-3) 14

Root Cause Analyses Comprehensive AFW Evaluation

Ø Prompt Corrective Actions- Complete

• Placed Modifications Developed using Old Process on Installation Hold Pending Accident Progression Review

• Implemented Multi-Discipline Review of Proposed Modifications by Management Team

Ø Interim Corrective Actions- Complete

• Implemented New Fleet Modification Process

• Implemented Design Review Board

• Assigned Issue Managers for Significant Station Issues

• Conducted Detailed Review of AFW Design and Licensing Bases (RC-2)

• Implemented the Corrective Action Program Improvements 15

Root Cause Analyses Comprehensive AFW Evaluation Additional Corrective Actions:

Ø Enhance Understanding of System Design and Accident Progression (RC-1)

• Upgrade Modification Process and EOP/AOP change process

• Develop and conduct training for Engineering and Operations

Ø Resolve Remaining Issues from AFW Design and Licensing Bases (RC-2)

Ø Develop and Conduct Training on AFW Design Bases (RC-2)

Ø Strengthen the Role of Engineering in the Development/Revision of Operations Procedures (CC-2)

Ø Upgrade Electronic Document Management System (CC-3)

Ø Continue Implementation of Corrective Action Program Improvements 16

Significance Determination 17

Significance Determination Historical Timeline Sept 2002 Key: AFW recirc Recirculation Line Orifice AOV open-Recirculation Line AOV function designated safety related March 2003 Replacement Dec 2001 (larger)

Nov 2000 U2 TD AFW pump May 2002 orifices A & B MD AFW anti-cavitation orifice U2 TD AFW pump installed on all pump anti-modification issued anti-cavitation AFW recirc cavitation orifice orifice installed lines installed 2000 2003 2001 2002 Oct 2002 June 2000 Nov 2001 *U1 TD AFW pump

• Identification March 2002 anti-cavitation orifice A & B MD AFW pumps of recirc line AOV U1 TD AFW pump installed anti-cavitation orifice issue. anti-cavitation orifice modifications issued modification issued

• Potential for orifice

• Procedures plugging identified modified to while testing A MD monitor recirc May/June 2002 AFW pump a few AOV position and Installed safety weeks later low instrument air related backup header pressure N2/air to all

• Procedures modified alarm to ensure AFW recirc to rely on forward AOVs minimum AFW flow to ensure min 18 flow flow

Significance Determination Events Affected by Orifices Dual Unit Events

Ø Loss of Offsite Power

Ø Loss of Service Water

Ø Loss of Instrument Air (Minor)

Ø Loss of DC Bus D02 Single Unit

Ø Transient (Minor)

Ø Transient without Heat Sink

Ø Steam / Feed Line Break (Minor)

Ø Loss of Component Cooling Water (Minor) 19

Significance Determination NMC Orifice Risk Increase- Unit 1* Risk due to orifice plugging mitigated by procedure changes Risk due to Risk due to orifice orifice plugging > 1 year plugging from identification

< 1 year from Calculated identification Base Risk Sept 2002 March 2003 Recirc AOV open- New orifices Nov 2000 function safety related installed on all A & B MD AFW Dec 2001 May 2002 AFW recirc pump orifice U2 TD AFW pump U2 TD AFW pump lines installed orifice mod issued orifice installed 2000 2001 2002 March 2002 2003 June 2000 U1 TD AFW pump Oct 2002 A & B MD AFW pumps anti-cavitation orifice

• U1 TD AFW orifice mods issued Nov 2001 modification issued pump orifice

• Fraction of year *Identification installed CDP affected by all of recirc line AOV May/June 2002 3 AFW pumps for Issue Installed AOV

• Plugging identified Unit 1= 0.06 *Procedures backup N2/air modified

• Procedures 20 changed

Significance Determination NMC Orifice Risk Increase- Risk due to Unit 2**

orifice plugging mitigated by Risk due to procedure orifice changes plugging

< 1 year from identification Risk due to orifice plugging > 1 year from identification Calculated Base Risk Sept 2002 March 2003 Recirc AOV open-New orifices Nov 2000 function safety related installed on all A& B MD AFW Dec 2001 May 2002 AFW recirc pump orifice U2 TD AFW pump U2 TD AFW pump lines installed orifice mod issued orifice installed 2000 2001 2002 March 2002 2003 June 2000 U1 TD AFW pump Oct 2002 A & B MD AFW pumps anti-cavitation orifice

• U1 TD AFW orifice mods issued Nov 2001 modification issued pump orifice

• Identification installed

• • Fraction of year of recirc line AOV May/June 2002 CDP affected by all Issue Installed AOV

• Plugging identified 3 AFW pumps for *Procedures backup N2/air Unit 2= 0.472 modified

• Procedures changed 21

Significance Determination- Event Timelines Events Time to CST Low- With Water Treatment Time to Initiate Notes Low Level System Clearwell Feed & Bleed (If Required)

Dual Unit Events

• Loss of Offsite Power, Loss 1.6 Hrs System Not Available 4.8 Hrs of Instrument Air, Loss of DC Bus D02, Loss of Service Water Single Unit Events

• Transients without Heat Not Required Not Required Not Required Normal CST Makeup Sink Available

• Transient without Heat Sink 2.1 Hrs System Not Available 5.5 Hrs and No Water Treatment

• Small LOCA 5.1 Hrs Not Required Not Applicable Three break sizes, with and (0.5 Break Only) without safety injection. Only smallest break reaches CST Low-Low Level

• Steam Generator Tube 3 Hrs 9.7 Hrs Not Applicable Rupture

• Main Steam Line Break 3.3 Hrs 12 Hrs 15 Hrs (Inside Containment)

• Main Steam Line Break 1.6 Hrs Not Required Not Required RHR conditions reached on (Outside Containment) CST inventory at ~2.2 hrs-prior to reaching SG level requiring feed & bleed.

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Significance Determination Differences for Plugged Orifice

Ø AFW Swap-Over Occurs Hours After Reactor Trip

• Decay Heat Lower

• Charging Successful for Feed and Bleed

• Shutdown Cooling Credited

• Steam Generator Depressurization and Service Water /Fire Water Addition Possible

• Emergency Response Facilities Staffed

• More Time for Troubleshooting and Recovery 23

Significance Determination NRC

Ø Preliminary Evaluation of Risk Increase Based on Phase 2 Analysis

Ø Assumed AFW Failure Probability of 1.0

Ø No Credit for:

• Initial Cooling by AFW

• Charging Feed and Bleed

• Transition to Shutdown Cooling

• Service / Fire Water Addition 24

Significance Determination NMC

Ø Internal Events Evaluated Probabilistic Risk Assessment

• MAAP (Modular Accident Analysis Program) used to Demonstrate Success and Determine Timeline of Recovery Actions

• Human Reliability Analysis for Credited Recovery Actions

Ø Seismic Events Evaluated using Seismic PRA

Ø Fire Event Analysis in Progress 25

Significance Determination NMC Risk Mitigating Factors Incorporated

Ø Water Treatment System

• Makeup to Condensate Storage Tank

• Clearwell Tank Makeup to CST

• Recovery Following Restoration of Off-Site Power

Ø Service/Fire Water through Disabled AFW Pump

Ø Charging for Feed and Bleed 26

Significance Determination NMC Risk Mitigating Factors Incorporated (contd)

Ø Changes to HEPs for Feed and Bleed

Ø Recovery of SI/ RHR Valves Left in Incorrect Position

Ø Operators Starting/Stopping AFW Pumps to Avoid Failure of 2nd and/or 3rd Pump 27

Significance Determination NMC Risk Mitigating Factors Not Incorporated

Ø Available 14,000 Gallons of Water Left in Each CST at Low Low Level

Ø Increase Charging to Maximum While in Loss of Heat Sink Procedure

Ø Likely AFW Pump Survival Time Following Swap-Over to Service Water

• Valve Leakage

• Packing Leakage

Ø Alignment of N2 to Pressurizer PORVs Following Loss of IA 28

Significance Determination Largest Contributors to Risk Largest Contributors Recovery Credited Initiator Water Service / Charging Shutdown Treatment Fire Water Feed & Cooling Bleed Loss of Offsite Power- x x x x Dual and Single Unit Transient w/o Heat Sink x x x Loss of DC Bus 2 x x x Loss of SW x 29

Significance Determination Sensitivity Analysis Factor Contribution to CDP Reduction (%)

Water Treatment System Impacts 91 Service Water/Fire Water through AFW Pump 48 Feed and Bleed HEP Change 48 Charging for Feed and Bleed 19 SI / RHR Valve Recovery HEP 10 Start / Stop AFWPs 5 30

Significance Determination Results Internal Events

Ø Increase in Internal Events Core Damage Probability

• Unit 1: High White

• Unit 2: Mid Yellow 31

Significance Determination Results External Events- Seismic

Ø Fragility Analysis Performed

Ø Charging, CST, and Service Water Addition Credited Following Safe Shutdown Earthquake

Ø Increase in Seismic Initiated Core Damage Probability

§ Unit 1: Green

§ Unit 2: Green 32

Significance Determination Results Increase in Internal Event and Seismic Initiated Core Damage Probability

ØUnit 1: High White

ØUnit 2: Mid Yellow 33

Significance Determination Results External Events- Fire

ØFire PRA Model Not Developed

ØDevelopment is in Progress

ØMethod Includes:

• Fire Initiation Frequency

• Detection Probability

• Automatic and Manual Suppression Probability

• Identification of Cables and Determination of Equipment Affected

• Credit for Mitigating Factors

• Consequences of Unsuppressed Fires

ØCompletion Targeted in August 34

Summary

Ø Installation of Inappropriate Orifice Design was Risk Significant

Ø NMC Significance Determination Preliminary Results (Internal and Seismic)

• Unit 1: High White

• Unit 2: Mid Yellow

§ Final Results, Including Fire, Targeted in August 2003

Ø Further AFW System Modifications

• Electrical Modifications in Progress

• Margin Recover Study

Ø Engineering Excellence Plan 35

Closing Remarks

Ø AFW Orifice Issue Self-Identified and Resolved in Timely Manner.

Ø AFW System Today is more Reliable.

Ø NMC Understands the Importance of the AFW Orifice Issue.

Ø NMC Significance Determination Preliminary Results (Internal and Seismic)

• Unit 1: High White

• Unit 2: Mid Yellow

Ø SDP for Fire Events Remains a Work in Progress.

Ø NMC Concurs with the Characterization of the Apparent Violation of 10 CFR 50 Appendix B.

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