05000271/LER-1989-019, :on 890501,primary Containment Isolation Sys Group III & Standby Gas Treatment Sys Initiations Occurred. Caused by Reactor Bldg Ventilation Radiation Monitor Sensor Malfunction.Sensor/Converter Replaced
05000267/LER-1989-013, :on 890811,12 Cable Trays in Auxiliary Electric Room Found Filled Above Design Limits.Caused by Error in Cable Tray Loading Computer Program Omitting Cables from Calculations.Program Corrected
05000454/LER-1988-008-07, :on 880921,radiation Monitor Detected Alert Radiation Condition During Movement of Reactor Vessel Upper Internals Assembly.Caused by Raising Reactor Vessel Upper Internals Assembly.Procedure Will Be Revised
05000424/LER-1992-001-02, :on 920415,stroke Time Testing Not Performed on Containment Isolation Valve to Demonstrate Operability,Per TS 4.6.3.1.Caused by Cognitive Personnel Error.Personnel Responsible for Error Counseled
05000321/LER-1991-022, :on 911009,setpoint Drift Discovered in 11 Main Steam Sys Safety Relief Valves.Caused by Corrosion Induced Bonding of Pilot Valve Disc & Seat.Valves Refurbished to Correct Lift Pressures
05000382/LER-1994-016-01, :on 940721,informed by Cooper Energy Svcs (CES) That CES Could Not Locate Documentation to Prove That Lube Oil Flow to Cooper Model ET-18 Turbocharger Would Be Adequate Under Loss of Control Air
05000443/LER-1994-016, :on 941019,noncompliance W/Ts 3.3.2 Action Requirements Noted.Caused by Acceptance of Inappropriate TS Reuqirements Re Emergency Bus UV Protection.Technical Clarification TS-059 Has Been Revised
05000374/LER-1990-007-02, :on 900421,reactor Protection Sys Bus a Transfer & Reactor Recirculation Hydraulic Power Unit a Inboard Isolation Valves Closed,Causing Partial Group II isolation.Out-of-svc Procedure Revised
05000296/LER-1989-004-04, :on 890906,unplanned Start of Diesel Generator 3D Occurred During post-maint Work Instructions.Caused by Personnel Error Re Inappropriate Prerequisites.Generator Stopped Immediately & Work Suspended
05000296/LER-1989-003, :on 890307,unplanned ESF Actuations Occurred. Caused by Voltage Transient Due to Start of Control Bay Chiller 3B Because of Design of Circuit Protectors Being Sensitive to Minor Electrical Disturbances
05000400/LER-1989-023-01, :on 891223,significant Difference Between Actual & Indicated Reactor Power Level for power-range Nuclear Instruments Noted.Caused by Installation of Low Leakage Core Loading Pattern W/O Adjustments
05000400/LER-1989-009-01, :on 890501,discovered That Monitoring for Radioactivity in Turbine Bldg Floor Drain Effluent Not Performed from 890429-30.Caused by Isolation of Sample Collection Path for Calibr of Detector
05000400/LER-1989-005-01, :on 890222,reactor Trip on Low Steam Generator Level W/Steam/Feedwater Flow Mismatch Occurred During Calibr Test Procedure.Caused by Performance of Section of Procedure Intended to Be Conducted.Procedure Revised
05000400/LER-1988-023, :on 880812,reactor Coolant Sys Vent Less than Required by Tech Spec 3.4.9.4 for Low Temp Overpressure Protection.Caused by Failed Valve Gagging Device.Longer Gagging Device Installed
05000400/LER-1987-059, :on 871011,incoming Line Breaker Tripped Initiating Safety Bus Blackout.Caused by Hammering & Drilling of in Relay Cabinet by Employee.Switchyard Breaker Reclosed & off-site Power Restored to Bus
05000400/LER-1987-027, :on 870426,during Test,Redundant Transmitter Pressurizer Pressure Channels Declared Inoperable.Caused by Two Out of Three Channels Out of Calibr & Reading Low. Channels Recalibr & Test Completed
05000400/LER-1987-026, :on 870423 & 24,main Feedwater Pump Tripped & Actuated motor-driven Auxiliary Feedwater Pumps.Caused by Trip of Condensate Booster Pump.Main Feedwater Restored & Pumps Secured.Control Logic Under Evaluation
05000250/LER-1989-018, :on 891212,use of Single Manual SI Block/ Unblock Switch for Both Trains of SI Outside Design Basis. Caused by Inadequate Original Plant Design.Info Re Potential Single Failure Mode Provided to Personnel
05000250/LER-1989-011, :on 890617,two Safeguards Actuations Occurred. Caused by Damaged Switch Contact Blocks & Personnel Error. Switch Contact Blocks Replaced & Personnel Counseled
05000250/LER-1989-002, :on 890116,normal Plant Cooldown Initiated Due to Small Boundary Leak of Rcs.Caused by Transgranular Stress Corrosion Cracking in Mapping Sys Thimble Guide Tube J-12 & J-7.Guide Tubes Involved Repaired or Replaced
05000251/LER-1987-025-02, :on 871012,containment & Control Room Ventilation Isolation Occurred.Cause by High Levels of Rb-88 in Containment Following Unit Shutdown.Particle Grab Sample Taken & Leak Rate Calculation Performed
05000251/LER-1988-003-01, :on 880207,shutdown of Unit from 100% Power Commenced Due to Exceeding Requirements of Tech Spec for Having Battery Charger 4S Out of Svc.Caused by Failure of Snubber Capacitor.Capacitor Replaced
05000251/LER-1987-021-01, :on 870729,process Radiation Monitor Spiked High Actuating Containment Vent & Control Room Ventilation Isolation Logic.Caused by Work Being Performed on Condenser Air Ejector Radiation Monitor.Drawer Reset
05000251/LER-1987-012-02, :on 870705,during Unit 3 Engineered Safeguards Integration Test,Auto Start of Component Cooling Water Pump 4B Occurred.Caused by Low Header Pressure on Increased Cooling Water Flow.Procedure Will Be Enhanced
05000250/LER-1987-023, :on 870913,safety Injection Sys Actuation & Subsequent Reactor Trip Occurred.Caused by Component Failure & Personnel Error.Event Response Team Formed to Investigate Causes & Initiate Corrective Action
05000316/LER-1993-002, :on 930219,determined That Condenser Air Ejector TS Sample Had Not Been Taken.Caused by Personnel Error.Appropriate Administrative Action Taken in Regards to Individuals Lack of Attention to Detail
05000315/LER-1991-004-01, :on 910512,while Performing Main Generator Max Reactive Capability Test,Rps (Reactor Trip Sequence) Occurred.Caused by Undervoltage Condition Sensed on RCP Busses.Defective Component Replaced
05000316/LER-1989-018, :on 891108,discovered That P-250 Computer Contained Incorrect Blowdown Constants for Thermal Output Program Entered on 891025.Caused by Lack of Administrative Controls.Zero Value for Blowdown Reentered
05000316/LER-1989-009, :on 890331,discrepancy Noted in Westinghouse P-250 Computer Calculated Thermal Power Value Which Could Lead to Exceeding Rated Thermal Power.Caused by Not Including blowdown-mass Enthalpy Term
05000315/LER-1988-009-01, :on 880927,lower Limit of Detection for Gross Radioactivity Not Met for Compensatory Samples.Caused by Misinterpretation of Tech Spec Required Value.Gamma Spectroscopy Analysis Will Be Performed
05000316/LER-1987-014-01, :on 871215,programming Error Causing Alarm to Be Inoperable,Discovered.Caused by Personnel Error.Computer Operators Counseled in Proper Method of Computer Software Troubleshooting & Program Installation
05000315/LER-1988-004-01, :on 880606,as Found Value of Neutron Flux High Rate Module Time Constant Incorrectly Adjusted.Caused by Improperly Aligned Test Recorder Input Filter.Power Range Channel Recalibr to Correct Values
05000316/LER-1988-002, :on 880205,identified That Surveillance Procedure Containing Channel Checks for Power Range Nuclear Instrumentation Did Not Require Channel Checks Below Mode 2. Caused by Personnel Error.Procedures Revised
05000315/LER-1987-008, :on 870604,ESF Actuation Occurred Due to Extreme High Level in Steam Generator 12.Caused by Mispositioning of Both Level Controller & Feedwater Flow Selector Switch.Level Controller Refurbished
05000316/LER-1987-011-01, :on 871002,Train a Safety Injection Signal Occurred.Caused by Personnel Error.Safety Injection Signal Reset,Plant Returned to pre-event Status & Personnel Reminded to Reevaluate When Work Exceeds Scope
05000528/LER-1991-007, :on 910822,determined That Normal HVAC Sys Cooling to Various ESF Pump Rooms Not Adequate.Caused by Not Recognizing That Normal HVAC Sys Was Not 100 Percent Redundant to Some Components.Guidance Issued
05000528/LER-1989-008-02, :on 890714,internal Audit Revealed Cooling Tower Sludge Contained Low Level Amounts of Radioactivity. Caused by Lack of Sludge Sampling Before Landfill Disposal. Approval to Dispose of Sludge Requested
05000528/LER-1988-006, :on 880321,determined That Allowable Surveillance Test Interval Had Been Exceeded for Incore Detector Sys.Caused by Personnel Error & Inadequate Programmatic Controls.Personnel Counseled
05000528/LER-1988-021, :on 880821,reactor Trip Occurred Due to High Pressurizer Pressure.Caused by Failure of Microswitch in Stator Coolant Flow Trip Circuit.Microswitch Replaced.W/
05000528/LER-1989-014, :on 890622,discovered That Seismic Monitor Had Been Disconnected & Inoperable Since 890422.Caused by Procedural Failure.Procedure for Removal of Reactor Coolant Pump Motor Being Revised to Alert Personnel
05000528/LER-1987-016, :on 870609,both Trains of ESF Pump Room Air Exhaust Cleanup Sys Inoperable.Caused by Personnel Error. Operations Dept Experience Rept & Night Orders Developed & Issued & Warning Tags Placed on Equipment
05000528/LER-1988-004-01, :on 880229,Mode 4 Entered W/Hpsi Injection Pumps Inoperable.Caused by Procedural Inadequacy.Procedure Revised to Include Steps to Ensure That HPSI Pumps Returned to Operable Status Prior to Entering Mode 4
05000530/LER-1987-003-02, :on 870929,condition Identified That,If Not Corrected,Could Have Resulted in Improper Operation of Two Shutdown Cooling Isolation Valves in Redundant Trains.Caused by Vendor Error.Bolting Replaced
05000529/LER-1987-021, :on 871202,post-accident Sampling Sys Declared Inoperable.Caused by Personnel Error.Appropriate Functional & Surveillance Tests Completed & Sys Decalred Operable.W/
05000529/LER-1987-015, :on 870816,control Room Essential Filtration Actuation Initiated on ESFAS Channels a & B.Caused by Voltage Spike on RU-30.Monitor Reset,Train B Returned to Svc & Procedural Change Initiated
05000529/LER-1987-019, :on 871122,reactor Trip Occurred Due to Core Axial Shape Index Out of Bounds.Caused by Deficient Procedure & Faulty Contact.Procedural Enhancements Initiated & Faulty Contact Replaced
05000397/LER-1991-009, :on 910417,ESF Actuation & RWCU Isolation Occurred When Electricians Cut Wires to Plug of Wind Direction Recorder,Causing Voltage Drop.Caused by Equipment Installation Error.Wires Reversed
05000397/LER-1989-030, :on 890210,HPCS Suction Valve from Suppression Pool Failed to Fully Open During Surveillance Procedure. Caused by Motor Operator HPCS-MO-15 Mfg Design Defect.Tech Spec Action Statements Entered & Valve Closed
05000397/LER-1988-012, :on 880606,potential Existence of Unmonitored Radiological Effluent Release Path During Certain Emergency Conditions Determined.Cause Unknown.Fan Disabled.Part 21 Related
05000397/LER-1988-009, :on 880401,standby Gas Treatment Sys Tech Spec Surveillances Not Performed within Time Limits.Caused by Personnel Error.Personnel Counseled & Procedure Revised to Provide Guidance When Surveillance Exceeded
05000389/LER-1989-005, :on 890626,reactor Tripped on Loss of Load from 22% Power During Turbine Startup Due to High Steam Generator Level in Steam Generator.Caused by Personnel Error.Personnel Counseled & Training Methods Evaluated
05000315/LER-1987-006, :on 870409,ESF Actuation,Main Steam Line Isolation Occurred.Caused by Failure of Current to Current Converter.Bistables for Channel IV Restored to Untripped Condition