05000413/LER-1989-012, :on 890107,6,900-volt Tie Breaker Tripped After Reactor Coolant Pump 1C Started,Causing Blackout & Loss of Power to RHR Pump,Fuel Cooling Pump & Component Cooling Pump.Caused by Error in Relay Installation
05000346/LER-1989-005, :on 890530,unit Experienced Reactor Trip from 100% Power Due to Loss of Condenser Vacuum.Caused by Failed Splice in One Phase of 13.8 Kv Feeder Cable.Faulty Load Cable Isolated & Unit Restarted
05000348/LER-1987-023, :on 871127,control Room Fire Dampers Inoperable Due to Failure to Close W/Air Flow.Caused by Design Deficiency.Implementation of Design Changes Expected within Next 6 Months
05000482/LER-1987-050, :on 871014,containment Isolation Valve Failed During Local Leak Rate Test.Apparent Cause of Valve Sticking Open Not Determined.Event Considered Isolated & No Other Corrective Action Planned
05000317/LER-1986-006-01, :on 861010,reactor Tripped Due to Loss of Load Trip as Result of Turbine Trip from Partial Loss of Condenser Vacuum.Caused by Operator Error.Operating Shift Will Be Briefed on Test Procedure
05000528/LER-1986-052, :on 860905,discovered Reactor Protection Sys Channel B Reactor Coolant Low Flow Trip Setpoint Set Nonconservatively.Caused by Personnel Error.Disciplinary Action Taken & Procedures Changed
05000336/LER-1986-009-02, :on 860929,automatic Actuation of ESF Sys Occurred.Caused by Personnel Error.On 861010,automatic Actuation of ESF Sys Occurred,Resulting in Containment Purge Isolation Signal.Caused by Noise Spike
05000260/LER-1986-014-01, :on 861003,crack Detected & Sized in Reactor Water Cleanup Sys Piping.Caused by Intergranular Stress Corrosion of Sensitized Type 304 Stainless Steel.Weld Will Be Repaired & Further Insp to Be Conducted
05000423/LER-1987-019, :on 870411,temp of Turbine Driven Auxiliary Feedwater Pump Area ES-07 Exceeded 110 F Limit Set by Tech Specs 3.714b & 6.9.2.Cause Not Stated.Equipment Not Affected According to Maint & Inservice Insp
05000296/LER-1986-008-03, :on 860905,LPCI Motor Generator Set Tripped from Shorted Generator Coil,Reducing RHR Capability.Damaged Generator Removed & Sent to Mfg for Repairs
05000298/LER-1986-016, :on 860813,reactor Scram Occurred.Caused by Lack of Proper Preplanning for Relay Replacement & Specific Procedural Guidance.Need for Preplanning of Maint Activities Reemphasized
05000346/LER-1986-026, :on 860703,results of Maint & Testing Identified Tubing in Atmospheric Vent Valves Too Restrictive to Achieve Required Closing Time.Tubing Between Air Cylinder & Vol Tank Redesigned
05000529/LER-1986-019-02, :on 860729,determined That Gas Grab Samples Not Taken & Analyzed within Required Time Limits Between 860721 & 860728.Caused by Personnel Miscommunication.Concurrent sign-offs Will Be Used
05000325/LER-1986-032, :on 861218,test Relay TR/2 in Logic Channels A2,A4,B2 & B4 of Turbine Bldg Area High Temp Instruments Not Functionally Tested.Cause Undetermined.Periodic Test Revised to Provide for Functional Testing
05000315/LER-1986-002, :on 860217,discovered That Three Reactor Trip Sys Interlock Setpoints Not Set Per Tech Spec Requirements. Caused by Misinterpretation of Tech Specs.Procedures Revised to Agree W/Tech Specs
05000338/LER-1987-001-01, :on 870127,7-day Period Allowed for Fire Pump to Be Out of Svc Exceeded.Caused by Inclement Weather & Further Repair Efforts.Pump Returned to Svc on 870213.W/
05000482/LER-1986-009, :on 860224,control Room Ventilation Isolation Signal Initiated Due to Loss of Sample Flow in Intake Radiation Monitors GK-RE-04 & GK-RE-05.Cause Unknown. Evaluation Continuing.Monitors Returned to Svc
05000245/LER-1986-032-01, :on 861230,two of Four Condenser Low Vacuum Pressure Switches Failed to Meet Tech Spec Setpoint Requirements During Routine Surveillance.Caused by Downward Mechanical Setpoint Drift.Switches Reset
05000298/LER-1987-009, :on 870218,reactor Scram Occurred Accompanied by Groups Ii,Iii & VI Isolations When Operating Reactor Feed Pump Mistakenly Tripped by Station Operator.Caused by Personnel Error.Error Reviewed W/Personnel
05000259/LER-1986-020-01, :on 860619,auto Start of Two Emergency Equipment Cooling Water Pumps Occurred.Caused by out-of- Calibr Raw Cooling Water Sys Pressure Switch.Monthly Calibrs Will Be Performed Until New Switch Installed
05000400/LER-1986-007-04, :on 861204,fire Hose Station Taken Out of Svc W/O Appropriate Compensatory Action.Caused by Personnel Error.Backup Suppression Established Immediately Following Discovery
05000245/LER-1986-027-01, :on 861130,reactor Scrammed Due to Main Transformer Fault,Resulting in Actuation of Generator Ground Relay & Causing Initiation of Turbine Trip Logic.Caused by Break in Winding Insulation
05000482/LER-1986-033, :on 860612,verification of Fuel Oil Properties Not Performed within 30 Days of Obtaining Fuel Oil Samples. Sys for Processing Lab Repts Improved
05000259/LER-1986-023-01, :on 860717,during Attempt to Put Switchyard Capacitor Bank in Svc,Reactor Scram Occurred.Caused by Incomplete Closing of Switchyard Disconnect & Mechanical Failure.Retraining Course Developed
05000213/LER-1986-020, :on 860508,automatic Reactor & Turbine Trip Occurred During Turbine Vibration Tests.Caused by Operator Accelerating Turbine at Too High Rate.Shift Supervisor & Operators Counseled
05000400/LER-1987-009, :on 870224 & 25,containment Leak Detection Radiation Monitor Noble Gas Channel Declared Inoperable. Caused by Procedural Deficiency.Advance Change 1/2, Correcting Deficiency,Approved
05000259/LER-1987-003-02, :on 870220,unplanned ESF Actuation Occurred During Transfer of 4 Kv Shutdown Board C to Alternate Power Supply.Caused by Circuit Protector Opening.Operating Procedure for Board Transfers to Be Revised
05000334/LER-1986-003, :on 860326,during Monthly Test for Diesel Generator,Area Smoke Detector Alarmed,But No Fire Alarm Received in Control Room.Caused by Two Inoperable Detectors. Test Procedure Revised
05000316/LER-1986-014, :on 860404,discovered That ESF Ventilation Sys HV-AES-1 Air Flow Rate Greater than Tech Spec Limit.Caused by Surveillance Procedure Deficiency.Procedure Will Be Revised to Include Addl Data
05000529/LER-1986-048, :on 860717,safety Injection Tanks (SIT) Inoperable Due to Wide Range Level Exceeding High Level Limit.Caused by Personnel Error.Order Stating Importance of SIT Level Monitoring During Heatup Issued
05000346/LER-1986-025, :on 860701,review of Tech Spec 3.3.3.8 Revealed Four Differences Between Installed Fire Detection Zones & Operability Requirements.Caused by Personnel Error.Fire Watch Established
05000413/LER-1986-014, :on 860312,periodic Surveillance Test to Exercise Control Rods Not Performed within Required Tech Spec Interval.Caused by Inadequate Procedure.Step 12.2 of Procedure PT/1/A/4600/01 Revised
05000333/LER-1997-012-01, :on 971214,drywell Personnel Airlock Outer Door Seals Local Leak Rate Test Was Not Properly Performed.Caused by Inattention to Detail on Part of Mechanic Who Installed Label.Removed Incorrect Label
05000528/LER-1986-051, :on 860930,determined That 50,000 Gallons of Effluent Chemical Waste Discharged to Evaporative Ponds W/O Sampling Since 860927.Caused by Cognitive Personnel Error. Procedure Revised Re Valve Identification
05000334/LER-1988-010, :on 871214,incore Instrumentation Thimble Tube Wear Discovered.Caused by Flow Induced Vibration.Tubes W/ Worst Wear Repositioned or isolated.Re-exam Planned Next Refueling Outage
05000334/LER-1988-011, :on 880103,one of 12 Bolts Which Secure Thermal Shield to Lower Core Barrel,Found Severed W/Threaded Portion of Bolt Extending Through Lower Core Barrel.Caused by Transgranular Fracture.Bolt Replaced
05000321/LER-1988-010-02, :on 880525,determined That Configuration of Recombiner Bldg Ventilation Radiation Noble Gas Monitors Defeated Annunciation Required by Tech Specs.Caused by Procedure Inadequacy.Procedures Revised
05000293/LER-1988-016, :on 880517,unexpected Actuation of Inboard Portion of Reactor Bldg Isolation Control Sys Occurred, Resulting in Closure of Train a Isolation Dampers.Caused by Personnel Error.Work Process Revised
05000293/LER-1988-021, :on 880719,discovered Problem Involving Solenoid Valves Installed in safety-related Applications. Caused by Incorrect Assumption.Mod Prepared to Replace Four Valves & Form Specifying Design Data Revised
05000289/LER-1988-002-02, :on 880619,pressurizer Level & Cooldown Rate Exceeded Due to Inadequate Test Procedure.Caused by Procedural Inadequacies.Test Procedure Will Be Revised to Prevent Recurrence of Event
05000366/LER-1988-003, :on 880117,spurious Valve Closure of RWCU Primary Containment Isolation Sys Noted.Caused by Spurious Isolation of Valve.Work Activities in Main Control Room & Other Sys Operations Reviewed
05000370/LER-1987-020-03, :on 871211,several Incidents on Both Units Where Plant Cooldown & Heatup Rates Exceeded Administrative Limits & One Violation of Tech Spec Limits.Caused by Personnel Error & Mgt Deficiency
05000424/LER-1987-076, :on 871127,instrument Panel 1-1513-P5-HMA Inoperable for More than 7 Days.Caused by Personnel Error. Personnel Counseled on Control & Temporary Storage of Matls During in-process Work
05000366/LER-1987-016-02, :on 871231,surveillance Not Performed within Time Limit.Caused by Personnel Error.Surveillance Performed, Verified & Schedule Modified.Personnel Counseled. W/88018 Ltr
05000424/LER-1987-072, :on 871121,Tech Spec Surveillance Re Readings from Plant Safety Monitoring Sys Data Displays Inadequately Performed.Caused by Inadequate Training of Auxiliary Plant Operator.Training Will Be Enhanced
05000370/LER-1986-004-03, :on 860321,during Maint,Esf Actuation Occurred Immediately Following Attempts to Remove Broken Drill Bit from Control Board.Cause Undetermined.Incident Will Be Reviewed as Supplementary Personnel Training
05000261/LER-1985-022-01, :on 850928,Exxon Nuclear Corp Informed Util of Error in Large Break LOCA Analysis Which Resulted in Peak Clad Temp Being Underpredicted.Reactor Power & High Flux Trip Setpoint Increased within New Limits
05000327/LER-1985-033-01, :on 850827,during Weekly Train B Chlorine Detector Function Testing,Esf Actuation Occurred for Main Control Room Isolation.Caused by Personnel Error.Personnel Counseled
05000423/LER-1985-003-01, :on 851214,while in Cold Shutdown,Emergency Bus 480-volt Ac Required to Be Operable Per Tech Specs Tagged Out of Svc to Perform Maint.Caused by Personnel Error.Bus Restored to Svc
05000382/LER-1985-053, :on 851212,discovered That Portion of Core Protection Calculator Tech Spec Functional Test Not Performed for Several Intervals.Caused by Procedural Change Eliminating Requirement.Procedure Changed
05000346/LER-1985-013, :on 850609,main Feedwater Pump 1 Tripped on Overspeed Due to Control Problem.Reactor Also Tripped on High RCS Pressure Because of Inadequate Feedwater.Corrective Actions Not Yet Determined
05000298/LER-1985-012, :on 851020,HPCI Sys Inoperable During Daily Exercising of Turbine Auxiliary Lube Oil Pump.Caused by Burned Commutator Segments & Shorted Armature Coils on Oil Pump Motor.Motor Rebuilt
05000281/LER-1984-015, :on 841029,during Breaker Testing,Load Shedding Initiated & Main Feedpump Tripped Leading to Low Steam Generator Level & Reactor Trip.Caused by Inadequate Procedures.Procedure Revised
05000267/LER-1985-022, :on 851015,circulator B Tripped on Low buffer- mid-buffer Differential Pressure.Caused by Small Amount of Buffer Helium Allowed to Vent Through buffer-mid-buffer Knockout Pot.Drain Procedure Revised
05000413/LER-1985-049-01, :on 850807,inadvertent Isolation of Both Discharge Headers of Fire Protection (Ry) Pumps Occurred. Caused by Personnel Error.Correct Ry Header Isolated. Procedure 2-18 Revised
05000382/LER-1985-029, :on 850630,reactor Trip Occurred Due to High Water Level in Steam Generator 2.Caused by Valve Positioners for Main Feedwater Regulating Valves Out of Adjustment. Positioners Adjusted
05000424/LER-1996-012-01, :on 961127,main Generator Stator Cooling Short Circuit Leads to Turbine/Reactor Trip.Caused by Metal Tag Coming in Contact W/Terminal Strip.Fuse Replaced & Metal Tags Removed
05000296/LER-1984-014-02, :on 841206,split Ring,Retaining Ring & Snap Ring Missing from Limitorque Valve Operator.Retaining Rings for Worn Shaft Gear Installed.Operator & Drive Motor Reassembled
05000366/LER-1984-010, :on 840924,reactor Water Cleanup (RWCU) Inboard & Outboard Isolation valves,2G31-F001 & 2G31-F004, Respectively,Isolated Due to High Differential Flow Signal. Caused by RWCU Demineralizer Not Full
05000373/LER-1996-002-08, :on 960323,TS Required Fire Watch Missed.Caused by Personnel Error & Breakdown in Communications Between Sys Engineers & Fire Watch Group.Fire Watch Staff Counseled & Retrained
05000387/LER-1984-010, :on 840225,reactor Manually Scrammed When One of Six Automatic Depressurization Sys Safety Relief Valves Stuck Open & Would Not Close in 2 Minutes.Caused by Faulty Valve Solenoid.Solenoid Replaced
05000348/LER-1995-005-01, :on 950611,spurious MSIV Closure Resulted in Reactor Trip.Caused by Water Intrusion from Room Cooler Leakage.Room Cooler Leak Repaired
05000321/LER-1981-112-03, Torus to Rx Bldg Differential Pressure Switches 1T48-N210,N211,2T48-N210 & N211 Proof Press Not within Tech Spec Limit.Caused by Switch Misapplication.Also Reported Per Part 21
05000029/LER-1990-006, :on 900811,emergency Diesel Generators Failed Tech Spec Surveillance Test.Investigation Team Formed to Review Testing History & Determine Cause.Design Change to Replace Emergency Diesel Generators Initiated
05000282/LER-1980-018-01, /01T-0:on 800701,unit Was Shut Down Due to Leaking Tube in Hot Leg of Vertical Steam Generator 12,Westinghouse Series 51.Cause Not Stated.Defective Tube Will Be Plugged
05000251/LER-1988-012-01, :on 880905,control Rod K-12 Dropped from 228 Steps to 0 Step,Causing Turbine Runback to 60% Power.Cause of Drop Under Investigation.Insp of Control Rod K-12 Will Be Performed During Current Refueling Outage
05000364/LER-1998-001-01, :on 980328,manual Reactor Trip Was Noted.Caused by Dropped Control Rod K-2 & F-10.Affected Cable & Connectors Were Replaced During Unit 2 Twelfth Refueling Outage & Tested During Startup
05000483/LER-1986-019, :on 860606,during Mode 1,reactor Trip Occurred on Low Pressurizer Pressure.Caused by Technician Deviation from Calibr Procedure.Progressive Discipline Administered. Guidelines Given to Technicians