05000528/LER-1991-004, :on 910320,supply Breaker Between non-Class IE 13.8 Kv Switchgear Buses Opened,Resulting in Loss of Power to Train a Class 1E 4.16 Kv Bus.Caused by Personnel Error. Preventive Maint Suspended
05000424/LER-1989-017-01, :on 890728,radiation Monitor ARE-2532B High Alarm Setpoint Resulted in Fuel Handling Bldg Isolation. Cause Unknown.Alarm Setpoint Raised & Procedure 35611-C Revised Re Panel Operating Steps
05000259/LER-1997-001-03, :on 970203,potential Overpressurization Containment Penetration Pipe Occurred Due to Thermal Expansion of Entrapped Water Was Identified.Plant Procedures Will Be Revised
05000352/LER-1985-011, :on 850116,fuse Supplying Power to Outboard Isolation Logic Relays in Nuclear Steam Supply Shutoff Sys Blew,Resulting in Isolation of Reactor Encl HVAC Sys.Caused by Electrical Short.Fuse Replaced
05000280/LER-1989-004, :on 890215,determined That Cable Tray Covers Did Not Comply W/App R Commitments Since Min Cable Separation Did Not Meet Reg Guide 1.75 Requirements.Caused by Improper Installation & Reinstallation
05000280/LER-1994-006, :on 940511,manual Reactor Trip Occurred During Safeguards Actuation Logic Testing.Caused by Inadvertent Actuation of Relay in Safety Injection Actuation Circuitry. Reactor Placed in Safe,Hot Shutdown Condition
05000220/LER-1990-006-01, :on 891027,discovered Unverified Assumption in App R Safe Shutdown Analysis.Caused by Fire Protection Program Failure to Provide Detailed Procedural Instructions for Operator Actions.New Procedures Developed
05000296/LER-1988-005-04, :on 881108,loss of Power to 4160 Volt Shutdown Board Due to Inadequate Breaker Alignment Causes ESF Actuations.Breaker Reinstalled & Properly Racked Into Normal Position
05000400/LER-1990-022-01, :on 901108,missed Surveillance Test for Secondary Waste Sample Tank Due to Incorrect Procedure Rev
05000400/LER-1990-019-01, :on 900824,potential Loss of RHR Sys Noted Due to Loss of Ccw.Caused by Sys Design
05000400/LER-1989-021-02, :on 891227,ESFAS Actuation Occurred Due to Loss of Main Feedwater Pump.Caused by Personnel Error.Sampling Valve Repaired,Appropriate Procedure Revised & Applicable Personnel Trained on low-flow Trips
05000400/LER-1990-014, :on 900516,discovered That Two Liquid Radioactive Releases Initiated on 900513 Were in Excess of Flow Rate Specified on Release Permits.Caused by Personnel Error.Max Release Rate Must Be Recorded
05000400/LER-1990-011, :on 900405,Tech Spec Violation Occurred Due to Missed Tests on Valve.Caused by Procedural Deficiencies. Procedures Revised & Plant Personnel Trained
05000400/LER-1990-008, :on 900314,discrepancy in Amperage Rating of Circuit Breaker Providing Overcurrent Protection for Containment Penetration Conductor Discovered.Caused by Use of Oversized Breaker.Breaker Upsized
05000400/LER-1989-015-01, :on 890827,discovered That Fuel Handling Bldg Operating Floor Equipment Hatch in Storage Location on Operating Deck Not Installed as Required.Caused by Inadequate Procedure.Procedure Revised
05000400/LER-1989-001, :on 890116,w/plant in Mode 1,reduction of Turbine Load Ensued & Turbine Trip Occurred Due to Low Condenser Vacuum Resulting in Automatic Reactor Trip.Caused by Personnel Error.Personnel Counselled
05000400/LER-1989-004, :on 890207,loss of All Three Circulating Water Pumps Resulted in Loss of All Flow to Main Condenser, Causing Reactor Trip.Caused by Air Entering Circulating Water Pump Seal Water Sys.Components Repaired
05000400/LER-1988-027, :on 880907,chemistry Technicians Failed to Obtain Gas Grab Sample at Required Time.Specific Technician Designated to Perform Compensatory Sampling Until All Compensatory Surveillance Requirements Met
05000400/LER-1988-029, :on 880915,short Equipment Start Pulses Generated,Causing Safety injection,motor-driven Auxiliary Feedwater & Emergency Svc Water Pumps to Start.Caused by Failure of Relay in Sequencer Test Circuit
05000400/LER-1987-039, :on 870619,intermediate Range (IR) High Neutron Flux Trip Setpoint Found Out of Calibr.Caused by Previous Adjustment to IR Setpoints.New Scaling Currents for 25% Trip Incorporated Into Applicable Procedures
05000251/LER-1990-007-02, :on 900726,component Cooling Water Pump 4A Automatically Started.Caused by Error Made by Nonlicensed Personnel.Pressure Controller PC-4-611 Recalibrated
05000250/LER-1990-021, :on 901018,determined That Length of Time CCW Headers Split for Movement of Heavy Loads Exceeded Appropriate Action Statement Time Limit That Should Have Been Imposed
05000250/LER-1987-030, :on 871027,determined That Existing Min Recirculation Design Configuration for RHR Sys Potentially Inadequate.Recirculation Flow Path for RHR Pumps Original Design of Plant.Mods Developed
05000250/LER-1987-015, :on 870522,design Basis Reconstitution Revealed Potential Loss of HVAC in Inverter & Battery Rooms.Caused by Mods to Original Plant Design.Maint & Insp Procedures Implemented for Air Conditioning Units
05000250/LER-1987-014, :on 870519,while Unit in Mode 6,determined That Design Discrepancy Existed in Containment Spray Sys.Caused by Flow Orifice in Discharge Line Not Incorporated in Field. Design Mods Will Be Implemented for Correction
05000250/LER-1987-016, :on 870526,while in Mode 6,partial Actuation of Train a Safeguards Equipment Occurred.Caused by Sticking Safety Injection Block Switch.Switch Inspected,Cleaned & Returned to Svc
05000250/LER-1989-007, :on 890316,surveillance for Snubber Missed. Caused by Weakness in Snubber Testing Program.Snubber Removed & Functionally Tested & Replaced W/Spare Snubber.W/
05000251/LER-1987-024-01, :on 871008,temp for Boric Acid Heat Tracing Circuit Number 6 Decreased Below 145 F.Caused by Cold Flushing of Crosstie Line.Flushing of Boric Acid Pump Crosstie Line Stopped & Sys Alignment Restored
05000250/LER-1987-024, :on 870913,reactor Controls Manipulated by Nonlicensed Person Under Supervision of Licensed Operator. Caused by Personnel Error.Personnel Counseled
05000250/LER-1988-003, :on 880308,containment Ventilation & Control Room Ventilation Isolation Occurred.Caused by Minor Electrical Transient Upon Failure of One Light Filament. Failed Dual Filament Bulb Replaced
05000316/LER-1988-001, :on 880106,Tech Spec 3.3.3.10 Discovered Not Met for 871230-880106 Due to Discovery of Incorrect Lineup for Radiation Monitor VRS-2500.Caused by Personnel Error. Flow Restored to Monitor & Lineup Verified
05000315/LER-1995-007, :on 950825,Conax Seal Assemblies on Rv Post- Accident Vent SVs 1-NSO-21 & 1-NSO-23 Found Loose.Missing Ferrules for 1-NSO-21 & 1-NSO-23 Replaced.Determined Event Not Reportable & LER 95-007-00 Cancelled
05000316/LER-1995-005-01, :on 950829,RT Occurred on High Negative Rate Resulted from Trip of Both CRD-MG Sets Due to mis-adjusted Voltage Regulators.Replaced CRD-MG Common Bus Overvoltage Relay Body
05000316/LER-1994-006-01, :on 940906,six MSSVs Failed to Meet TS Lift Setpoint Requirements.Caused by Galling Between Valve Disk & Nozzle.Nrr Issued TS Amend 167 to Unit 2 Ts,Increasing MSSV Tolerance on 940909
05000315/LER-1994-003, :on 940311,main Steam Safety Valve Test Inaccuracy Due to Miscalculation of Valve Seat Area by Vendor.Mssvs Retested After Entering Mode 3
05000316/LER-1993-003, :on 921016,discovered That Charcoal Filter Face Dampers Were Closed Instead of Open as Indicated.Caused by Incorrect Solenoid Installation.Procedures Revised & Dampers Verified to Be Installed Correctly
05000315/LER-1992-006-02, :on 920618 & 19,10 of 20 Main Steam Safety Valve Lift Settings Found Outside of TS Tolerances.Caused by Setpoint Drift.Valves Reset to Acceptable Values & Retested Satisfactorily
05000316/LER-1993-008, :on 930827,reactor Trip Occurred from Steam Flow/Feed Flow Mismatch Coincident W/Low Level in SG 4. Defective current-to-current Repeater Replaced
05000315/LER-1992-012, :on 921028,Turbine Trip/Reactor Trip Occurred During Power Increase to 30% to Perform Routine Calometric Test.Caused by Failure to Reset Thrust Bearing Wear Detector Setpoint.Procedures to Be Drafted
05000315/LER-1991-006, :on 901129,facility Outside Design Basis for Separation of Safety Related & Nonsafety Related Circuits. Caused by Personnel Error.Design Procedures Revised
05000316/LER-1992-007-01, :on 920702,reactor Tripped from Turbine Trip Coincident W/Turbine Power Greater than 10%.Caused by Sudden Loss of Main Condenser Vacuum During Diagnostic Testing. Procedure Enhancements Made
05000315/LER-1990-008, :on 900619,discovered That Isolation Relay Circuitry for Low Header Pressure Auto Start Switch for Essential Svc Water Pumps Installed Incorrectly.Caused by Design Errors.Plant Mod Packet Initiated
05000316/LER-1990-002, :on 900108,two MSIVs Exhibited Closing Time in Excess of Tech Spec 3.7.1.5 Limit of 5 S.On 900109 & 10, Confirmed That Excessive Condensation Collected on Vent Side.Caused by Inadequate Insulation
05000315/LER-1990-004-01, :on 900508,reactor Operator Inadvertently Started Containment Recirculation Fan Instead of Hydrogen Recombiner During Surveillance Test.Caused by Inadequate Work Practice.Condenser Restored
05000316/LER-1991-002-01, :on 910220,discovered That Previous Procedure Rev Omitted Fire Damper from Insp List & Damper Not Included in Surveillance.Cause Not Conclusively Determined.Damper Visually & Functionally Inspected
05000315/LER-1989-001-01, :on 890116,erroneous Operation of Control Switch for Condenser Air Off Takes to Startup Air Ejectors Occurred.Caused by Inadequate self-checking.Switches Labeled & Operator Training Emphasis Made
05000528/LER-1996-002-02, :on 960514,Tech Spec Violation Occurred Due to Erroneous Surveillance Requirement.Caused by Incorporation of C-E Generic Ts.Investigation Being Conducted
05000528/LER-1998-001, :on 980130,reactor Protection & ESFAS Instrumentation Not Bypassed within one-hour Allowed by TS Occurred.Caused by Inadequate Procedures.Expectation to Detect Alarm Conditions Was Emphasized to CR Personnel
05000528/LER-1991-003, :on 910208,determined That Essential Spray Pond cross-connect Valves Not Verified in Correct Position. Caused by Failure to Meet TS Surveillance Requirements. Valve Positions Verified & Valves Locked Shut
05000528/LER-1989-020, :on 890907,emergency Diesel Generator B, Essential Spray Pond Pump B & Essential Cooling Water Pump B Started During Removal of Jumpers.Caused by Personnel Error. Maint Procedure Revised
05000530/LER-1989-004, :on 890104,exhaust Rocker Arm for Cylinder 8L Failed,Resulting in Emergency Diesel Generator Trip.Caused by Crack in Rocker Arm.On 890107,ESF Actuation Occurred.Also Reported Per Part 21.Rocker Arm Redesigned
05000530/LER-1989-001, :on 890303,electrical Grid Disturbance Resulted in Main Generator Output Breakers Opening,Resulting in Reactor Power Cutback & Steam Bypass Control Sys Actuation. Caused by Malfunction in Subj Control Sys
05000528/LER-1989-019, :on 890929,Train B of Fuel Bldg Essential Ventilation Actuation Sys Spuriously Actuated.Caused by Loose Connection Between Radiation Monitor Remote Indication & Control Unit Instrument Drawer & Cabinet
05000530/LER-1989-013-01, :on 890926,control Room Operator Inadvertently Turned Wrong Handswitch During post-maint Testing Which Resulted in ESFAS Actuation.Caused by Personnel Error. Disciplinary Measures Taken
05000528/LER-1989-007, :on 890412,discovered Two of Four Pressurizer Code Safety Valves Out of Tech Spec Tolerance of 2,500 Psia Plus or Minus 1%.Caused by Performance Limitation.Valves Adjusted & Retested Satisfactorily
05000528/LER-1990-003, :on 900320,log Power Channels Declared Inoperable When Plant Protection Cabinets Deenergized for Scheduled Maint.Caused by Personnel Error.Wiring in Cabinets Reworked & Cabinets Returned to Svc
05000528/LER-1990-001, :on 900220,radiation Monitor Indication Spike Resulted in ESF Actuation.Caused by Noise in Radiation Monitor Common Ground Circuit & Cognitive Personnel Error. Mod Performed to Circuit & Personnel Counseled
05000528/LER-1991-001, :on 910110.determined That Postulated Break in Reactor Coolant Pump High Pressure Seal Cooler Could Result in RCS Leak Outside Containment.Caused by Tube Rupture in Seal Cooler.Rcs Activity Monitored
05000530/LER-1990-002, :on 900222,locked High Radiation Area Gate Found Open & Unguarded.Caused by Personnel Error.Radiation Protection Personnel Verified Room Unoccupied & Secured Gate Per Approved Procedure
05000530/LER-1990-001, :on 900127,spurious Train B Containment Purge Isolation Actuation Signal Initiated on Balance of Plant Esfas.Caused by Spiking of Radiation Monitor RU-38 Due to Malfunctioning Central Processing Unit
05000529/LER-1990-001-02, :on 900223,manual Reactor Trip Occurred During Planned Shutdown.Caused by Axial Shape Index Approaching Limit at End of Core Life Shutdown.Reactor Manually Tripped So That Channel Trip Setpoint Not Exceeded
05000528/LER-1987-009-01, :on 870604,inadvertent Control Room Essential Filtration Actuation Occurred Due to Radiation Monitor Pump Cycling.Caused by Motor Drawing Too Much Current.Ground to Motor & Radiation Monitor Separated
05000528/LER-1988-005, :on 880123,backhoe Operator Inadvertently Damaged Post Indication Valve (Piv)(Kp)(Isv) & Caused Fire Suppression Water to Discharge Into Protected Area.Caused by Inadequate Procedure.Procedures Implemented
05000530/LER-1989-005-01, :on 890628,sample Flow Rate for Vent low-range Radioactive Effluent Monitor Below Low Flow Alarm Setpoint, Rendering Monitor Inoperable.Caused by Loose Set Screw on Coupling.Set Screw on Sample Pump Tightened
05000528/LER-1989-017, :on 891023,four Unsealed Penetrations in Unit 3 Seismic Gap Area Discovered During Visual Insp of 94 Ft Elevation Diesel Bldg Pipe Trenches.Fire Watches Established in All Units.Sealing of Penetrations Underway
05000397/LER-1994-004, :on 940307,two in-series Containment Isolation Valves MS-V-16 & MS-V-19 Inoperable Since 931217.Caused by Ambiguous Wording in Dec 1993 Operability Assessment. Procedures Modified & Training Provided
05000397/LER-1991-013, :on 910507,non-compliances W/Tech Specs Identified as Part of Program of Surveillance Procedure Verification.Further Evaluation Performed.Quality Action Team to Be Chartered to Evaluate Program
05000397/LER-1990-022, :on 900930,pressure Decrease Occurred in Containment Instrument Air Sys When Nitrogen Cryogenic Tank Was Inadvertently Depleted.Containment Nitrogen Inerting Procedures PPM 2.3.1 & 2.3.7 Revised
05000397/LER-1989-033, :on 890811,RWCU Isolation Occurred When Fuse in Power Supply to Leak Detection Monitor Blew,Giving False High Alarm Signal to Isolation Logic.Cause Unknown.Fuse Replaced & RWCU Sys Restored to Operation
05000397/LER-1989-036, :on 890905,discovered That Present Surveillance Procedures Do Not Provide for Independent Measurement of Two Values.Caused by Less than Adequate Surveillance Procedures on Response Time Testing of APRM Sys
05000397/LER-1990-026, :on 901024,inadequate Electrical Power Supply Separation Discovered in Two Control Room Panels Due to Design Error
05000397/LER-1989-020, :on 890527 & 0605,during Local Leak Rate Testing,Valve RHR-V-9 Automatically Isolated.Caused by Procedural Inadequacy & Inadequate Corrective Action Following Second Event.Procedure Modified
05000397/LER-1989-005, :on 890311,34 of 185 Control Rods Drifted Inward from One to Seven Notches.Caused by Main Steam Line Radiation Monitor Design Deficiency.Desired Rod Pattern Reestablished
05000397/LER-1988-023, :on 880629,Tech Spec Violation of Secondary Containment to Outside Differential Pressure Occurred.Caused by Sys Configuration Error.Instrument Setpoint Change Request Initiated
05000397/LER-1988-017, :on 880615,problems W/Limitorque Models SMB-000 & SMB-00 Discovered W/Potential Defective Switches.Caused by Design Problem.Investigation & Evaluation of Switch Problems Immediately Initiated.Part 21 Related
05000397/LER-1989-015, :on 890512,three-quarter-inch High Point Vent Line Failed During Performance of HPCS Sys Operability Procedure.Caused by Reverse Bending Fatigue Caused by Vibration.Design Change Implemented
05000397/LER-1987-018, :on 870626,reactor Automatically Scrammed by Reactor Protection Sys Actuation Due to Normal Auxiliary Power Transformer Sudden Pressure Relay Actuation.Caused by Opening of Test Valve.Transformers Inspected
05000397/LER-1987-005, :on 870421,reactor Containment Inboard RHR Shutdown Cooling Supply Valve Automatically Isolated.Caused by Personnel Error.Lifted Neutral Lead Replaced.Relay RHR-V-9 Reopened & Plant Engineer Counseled
05000244/LER-1999-009, :on 990503,instrumentation Declared Inoperable in Multiple Channels Resulted in Condition Prohibited by Ts. Caused by Unanticipated High Frequency AC Voltage Ripple. Entered TS LCO 3.0.3.With
05000244/LER-1992-005, :on 920420,determined That 242 Tubes in a SG & 216 Tubes in B SG Required Corrective Action Due to Tube Degradation.Affected Tubes Either Sleeved or Plugged.W/
05000388/LER-1991-009, :on 910624,RWCU Steam Leak Detection Instrumentation Discovered to Be Inadvertently Actuated During Routine Functional Testing.Caused by Adequate Verbal Communication.Technicians Briefed
05000335/LER-1987-014-02, :on 871008,unidentified RCS Leakage Greater than Tech Spec Limit Discovered.Caused by Weld Joint Failure Due to Previous Misalignment of Listed Flanges.Reactor Shut Down & Required Repairs Performed
05000389/LER-1987-003-03, :on 870409,during Troubleshooting,Jumper Placed on Wrong Terminal of Main Steam Isolation Signal (MSIS) Actuation Pushbutton Circuitry,Causing Actuation of Msis. Caused by Cognitive Personnel Error
05000335/LER-1987-006-02, :on 870322,spurious Main Steam Isolation Occurred When Energized Wires Inadvertently Allowed to Make Contact W/Metal Cabinet.Caused by Personnel Error.Personnel Instructed on Working W/Energized ESFAS
05000335/LER-1987-009-01, :on 870412,ECCS Emergency Exhaust Fan Radiation Monitor Failed Resulting in Inoperability of Fuel Handling Bldg Exhaust Stack Radiation Monitor.Caused by Equipment & Personnel Error.Monitors Restored to Svc
05000389/LER-1987-005-03, :on 870527,while Operating in Mode 1,control Element Assemblies 5 & 7 Simultaneously Dropped to Bottom of of Core.Possibly Caused by Random Intermittent Failure of Control Element Drive Mechanism Component
05000458/LER-2014-003-01, Regarding Operations Prohibited by Technical Specifications Due to Concurrent Inoperability of Reactor Protection System Channels
05000321/LER-2009-006, Regarding Main Control Room Air Conditioner Inoperable Due to Inoperable Solenid Valve
05000454/LER-2007-002, Technical Specification Required Shutdown of Unit 1 and Unit 2 Due to an Ultimate Heat Sink Pipe Leak Common to Both Units
05000400/LER-1992-012-02, :on 920802,one of Three Secondary Relays Failed to Actuate,Causing TS 3.0.3 to Be Entered.Caused by Failure of under-voltage Relay to Actuate.Procedure Will Be Revised to Provide Guidance for Tripped Condition