ML071080406

Emergency Diesel Generator No. 1 Trip and Failure of Engine Crankshaft Bearing

ML071080406
Person / Time
Site:	Brunswick
Issue date:	04/05/2007
From:	Progress Energy Carolinas
To:	Office of Nuclear Reactor Regulation
Shared Package
ML071080396	List: ML071080399 ML071080406
References
Download: ML071080406 (30)

Text

Brunswick Nuclear Plant Emergency Diesel Generator No. 1 Trip and Failure of Engine Crankshaft Bearing IntroductionScotty HinnantSenior VP & CNOJim ScarolaSite Vice PresidentSteve HowardManager OperationsRandy IveyManager Support ServicesSusan RogersManager MaintenanceTim TraskManager EngineeringBob RishelSupervisor -PSA Agenda Opening Remarks Event Review Diesel Generator Reliability Mitigating Systems Key Lessons Learned Closing Comments Opening Remarks BNP agrees with the finding and preliminary significance determination.

EDG 1 -Sequence of EventsPlanned Maintenance October 23 -30 Oct 23 rd -EDG 1 Removed From Service For Planned Maintenance Activities. Corrective MaintenancePreventive Maintenance72 Month Inspection ActivitiesMargin ImprovementPower Potential Transformer Replaced EDG 1 -Sequence of EventsPlanned Maintenance October 23 -30 Oct 29 th EDG 1 AvailablePost-maintenance testing run, lubricating oil strainer high differential pressure alarms were

received Oct 28 th& 29 thPost maintenance activitiesEDG 1 started and was run 5 timesCumulative run time ~15 1/2hours Oct 30 th EDG 1 declared operable At Power Electrical System Lineup U2 SAT Flex Link on Phase A Fails Operators Insert Manual Trip on U2 Loss of Offsite Power Unloaded DG 1 Trip Backfeed Established Emergency Power Loads EDG 4 E4 Division II EDG 3 E3 Division I EDG 1 E1 Division I EDG 2 E2 Division II CSW Pump 1A RHR SW Pump 1B RHR SW Pump 2B CSW Pump 2B RHR Pump 1B Fire Pump CS Pump 2B RHR Pump 2B NSW Pump 2B E4 Loads RHR SW Pump 1A RHR SW Pump 2A CSW Pump 2A RHR Pump 1A CS Pump 2A RHR Pump 2A NSW Pump 2A E3 Loads CSW Pump 2C RHR SW Pump 2C RHR SW Pump 1C CSW Pump 1A RHR Pump 2C CS Pump 1A RHR Pump 1C NSW Pump 1A E1 Loads RHR SW Pump 2D RHR SW Pump 1D CSW Pump 1C RHR Pump 2D Fire Pump CS Pump 1B RHR Pump 1D NSW Pump 1B E2 Loads Unit 2 Unit 1 EDG 1 Trip On Low Lube Oil Pressure EDG 1 Trip On Low Lube Oil Pressure High Differential Pressure Caused By:Aluminum shavings from failed bearingFibrous material from towel left in system during maintenance

activities EDG 1 Trip On Low Lube Oil Pressure Root Cause of Trip: Inadequate FME controls resulting in a cleaning cloth left in lube oil system Contributing Causes:

-Method of refilling LO duplex strainer basket while DG running

-Rationalized cleaning duplex strainer multiple times following maintenance as normal

-Shavings from failed bearing contributed to high dp EDG 1 Trip On Low Lube Oil Pressure Inadequate Worker Practice Action to Prevent Recurrence: Establish High FME Job Classification for the DG Crankcases Immediate Actions:Improved High FME ControlAccountability for Cleanliness Closeout Failure Of Main Journal Bearing #9 Bearing Failure Occurred Prior to Diesel Trip Bearing Damage/Cracking Probably Occurred Prior to Final Run Damage Similar to 1992 Failure of Same Bearing Bearing # 9 in

Service 14 years Prior Bearing in Service 16 years Failure Of Main Journal Bearing #9 Cause: Increased Crankshaft Bearing ClearancesResulted In Lower Initial Bearing CrushGreater Operational Stresses on Bearings Failure Of Main Journal Bearing #9 Action to Prevent RecurrenceReplace DG1 Main Journal Bearings With Oversized Bearings Failure Of Main Journal Bearing #9 Other Corrective ActionsDetermine Methodology for Performing Lift ChecksInstall New BearingsEstablish Accurate Bearing Clearance MeasurementPerform plastigauge or similar measuring techniqueReplace Main Journal Bearings on DG #2, #3 and #4 Evaluate Bearing WearEstablish Preventative Maintenance ActivitiesReplace Connecting Rod Bearings on All DG'sDetermine Acceptable Babbitt Thickness Diesel Generator Reliability Review Completed in January 2007 Performed Pareto Analyses using key inputs:MSPIMaintenance RulePlanned and Unplanned UnavailabilityCorrective Action ProgramWork OrdersSelf Assessments, Benchmarks, Audits, NRC InspectionsVendor Input / Industry OE Diesel Generator Reliability Review Key Reliability Improvements Items Allen Bradley Control RelaysAll Normally Energized Critical Relays replacedEDG #3 and #4 Normally De-energized Critical Relays replaced in Refueling OutageEDG #1 and #2 Normally De-energized Critical Relays to be replaced before June 2007 Starting Air Reconfiguration and Improvements6 of 8 Pressure Reducing Valves replaced. EDG #2 to complete before June 2007.6 of 8 Shuttle Valve replaced. EDG #1 to complete before June 2007.Design work commencing to change from air-to-run to air-to-stop Aging of Capacitors in Control System30 of 56 Capacitors replacedSpecial Manufacturing Run in progressNo current evidence of degradation. Power Potential Transforme r replaced on all EDGsEDG #3 and #4 logic upgrade (27 PK Relays) complete. EDG #1 and #2 in Unit 1 2008 Outage. EDG #1 Bearings Diesel Generator Reliability Preventive Maintenance EvaluationIn Progress, To Complete in May 2007 ObjectivesValidation of component criticalitiesUpgrade of existing functional equipment groupsIdentification of single-point vulnerabilitiesStrengthening of PM basis Identification & prioritization of health issuesSystem monitoring improvements Diesel Generator Reliability Interim Actions Increased Monitoring During EDG runs:Thermography of electrical cabinets / componentsMonitoring of critical engine parametersMonitoring of operation and health of support systems Diesel Generator Reliability Technology TransferEngine Solution Inc. to acquire NAK Technology (current vendor for Nordberg

EDGs)Joint Progress Energy / Duke agreementEnsures continued and improved vendor

support for EDGs Other Mitigating Systems Mitigating System ReliabilityReviewing mitigating systems for similar vulnerabilitiesService WaterHigh Pressure Coolant InjectionResidual Heat RemovalReactor Core Isolation CoolingDetailed review of NCRs generated over the

past 5 years Lessons Learned Technical Rigor FME Culture and Practices Improved Contingency Plans Corrective Action Program Improvements Closing Comments Mr. Scotty Hinnant Senior Vice President and Chief Nuclear Officer Questions & Comments