05000259/LER-1988-036-01, :on 881018,two Possible Unanalyzed Electrical Loading on Safety Related Electrical Sys Identified.Caused by Inadequate Design Control & Review Program.Accident Signals from Units 1 & 2 Disabled
05000260/LER-1989-010-01, :on 890323,radiation Monitor Experienced Downscale Spike Following Upscale Spike,Resulting in Unplanned ESF Actuations.Caused by Arcing from Exposed Conductors on Communication Line.Cord Taped
05000352/LER-1987-019, :on 870525,during Surveillance Test on Reactor Water Level Transmitter,Transmitter Vented Before Being Isolated Causing Pressure Oscillations.Caused by Personnel Error.Low Level Water Signal Reset
05000331/LER-1986-019, :on 860922,250-volt Dc Battery Declared Inoperable.Caused by Degradation of Positive Plates Due to Galvanic Reaction Resulting from Impurities in Plate Weld Matls.Battery Tested & 16 Cells Replaced
05000440/LER-1986-062, :on 860916,drywell Vacuum Relief Valve Opened Automatically.Caused by Conservative Drywell Valve Relief Sys Relief Valve Setpoints.Drywell Valve Relief Actuation Setpoints Raised
05000414/LER-1986-030-01, :on 860708,reactor Tripped on lo-lo Steam Generator Level.Caused by Personnel Error.Main Feedwater Isolation Signal Reset,Main Feedwater Pump Turbine Started & Flow to Steam Generators Restored
05000269/LER-1987-002-04, :During Wk of 870127,determined That Operators May Not Be Able to Isolate Particular Letdown Flow Path. Caused by Design Deficiency.Power Removed from Breakers for Valves LP-1 & HP-2 on 870129
05000302/LER-1997-008, :on 970307,discovered Potential for Possible Pump Failure & Dose Consequences.Caused by Design Errors. Will Keep Plant in Shutdown Until Design Deficiencies Are Resolved & Will Initiate Plant Modification
05000370/LER-1985-024-02, :on 851014,gradual Decrease in Indicated Value of full-power delta-T Identified.Caused by Change in Hot Leg Temp Streaming Pattern Supplying Coolant Samples to Temp Sensors.Calibr Procedure Developed
05000333/LER-1996-012-01, :on 961111,primary Containment Accumulative Leakage in Excess of Maximum Allowed by TS Occurred.Caused by Build Up on Valve Seat Areas.Efes Were Completed for Each Failed Valve
05000302/LER-1995-028, :on 951213,operation Was Outside Design Due to Personnel Errors & Inadequate Documentation of Borated Water Storage Tank Vacuum Breaker Capacity.Initiated Work Request to Remove & Inspect DHV-69
05000333/LER-1996-005-01, :on 960506,error in Safety Limit Minimum Critical Power Ratio (MCPR) Calculation Occurred.Caused by Error in Calculation of Methodology.Administrative Controls Re Operating MCPR Instituted
05000336/LER-1996-005-01, :on 960212,discovered PEO Improperly Utilized to Replace Automatic Backwash Function of Svc Water Strainer Backwash Sys.Caused by Failure to Enter TS Action Statement. Revise Procedures for IST SWS Pump Operability
05000446/LER-1996-002, :on 960126,noted That TS Surveillance for Turbine Overspeed Missed Due to Oversight in Rescheduling Required Surveillance by Cognizant Personnel.Test Completed on 960126 & Event Reviewed as Lesson Learned
05000388/LER-1985-009, :on 850212,setpoints for Three Reactor Water Level Switches Found to Be Outside Acceptance Criteria During Performance of Scheduled Surveillance.Caused by Instrument Drift.Instruments Recalibr
05000336/LER-1996-002, :on 960108,determined That Ice Plug in Common Line Resulted in Inability to Backwash Svc Water Strainers. Caused by Mod to Backwash Line Piping.Ice Plug Removed, Restoring Ability to Backwash
05000336/LER-1995-045, :on 951214,plant Shutdown Initiated Due to Indeterminate Structural Integrity of Charging Valve 2-CH-435.Repaired Valve
05000456/LER-1995-013-04, :on 951012,fire Protection App R Design Discrepancies Occurred Due to Inadequate Evaluations During Preparation of Original Analysis.Maintained Hourly Fire Watches for All Fire Zones
05000445/LER-1992-002, :on 920115,discovered That Surveillance Requirement for Area Temp Monitoring Not Performed in TS Required Interval of Once Per 12 H.Caused by Personnel Error.Control Over Assignment Improved
05000369/LER-1984-001-01, :on 840109,unauthorized Removal of Safety Injection,Main Feedwater & Component Cooling Sys Support/ Restraints Discovered.Support/Restraints Reinstalled, Repaired or Deleted as Appropriate
05000321/LER-1984-004-01, :on 840327,personnel Found That Scram Discharge Vol High Level Thermal Level Sensors 1C1L-N060 A-D Not Functionally Tested at Required Frequency.Caused by Lack of Procedure.Procedure Written & Implemented
05000334/LER-1995-004, :on 950301,five MSSV Determined by Testing to Be Outside TS 3.7.1.1 Tolerance of +1%-3%.Caused by Vendor Provision in Incorrect Mean Seat Area Data Used.Made Adjustments on Six Affected Safety Valves
05000334/LER-1994-010, :on 941114,air Leak Found at Air Sys Drain Trap Resulting in CR Emergency Habitability Sys Being Inoperable. Caused by Corrosion in Trap Drain Valve of VS-C-1A1 Air Dryer.Subj Valve Removed,Cleaned & Replaced
05000414/LER-1990-013-01, :on 901007,reactor Trip Occurred Due to low-low Level in 2D Steam Generator Due to Equipment Failure Resulting in Reactor & Main Turbine Trip.Event Reviewed & Investigated
05000445/LER-1990-014, :on 900514,containment Penetration Improperly Isolated While Containment Isolation Valve Made Inoperable for Repairs.Caused by Inadequate Review of Work Order. Supervisor Counseled & Shift Order Issued
05000423/LER-1989-024, :on 891010,inconclusive Test Results for MSIV C Obtained During Quarterly MSIV Partial Stroke Surveillance. Caused by Inadequate Procedural Guidance for Identifying Correct Acceptance Criteria
05000280/LER-1989-017, :on 890508,discovered That Tech Spec for Sampling Svc Water from a & B Component Cooling HXs Not Satisfactorily Performed.Caused by Personnel Error.Samples Taken After Incident Verified as Correct
05000280/LER-1988-035, :on 880914,specific Activity Sample of Reactor Coolant Showed Dose Equivalent I-131 Level of 1.04 Microcuries/Cc,Exceeding Tech Spec Limits.Caused by Iodine Spike Due to Fuel Element Defects
05000280/LER-1988-022, :on 880710,unit Ramped Down to Shutdown.Caused by MOV-CS-101B Leakage Due to Lost Motion in Shaft & Linkage Between Motor Operator & Shaft.Valve Disassembled & Valve Seat & O-rings Replaced
05000255/LER-1995-007, :on 950720,discovered That 12 Instrument Loops Had V-bolted Type Qualified Cable Splices Connected to Wires W/Exposed Kapton Insulation.Caused by Human Error.All V- Bolted Splices Replaced w/in-line Design
05000400/LER-1987-019, :on 870412,manual Plant Trip Initiated Due to Loss of Feedwater Trains & Decreasing Steam Generator Levels.Caused by Condensate Pump High Temp Trip.Pressure & Steam Generator Levels Restored
05000250/LER-1989-005-01, :on 890215,auxiliary Feedwater Flow Automatically Initiated Following Attempt to Start Steam Generator Feedwater Pump.Caused by Wiring Error on Starting Circuit Relay.Wiring Error Corrected
05000251/LER-1988-005-01, :on 880425,calibr of Nuclear Instrumentation Sys Power Range Detectors Performed Late.Caused by Personnel Error.Digital Data Processing Sys Repaired & Group Responsible for Performance Discussed Event
05000387/LER-1989-019, :on 890526,determined That Damaged Fire Seals Inoperable.Caused by Failure to Identify Penetration Seal Damage on Fire Rating/Operability of Penetrations.Fire Watch Established
05000354/LER-2016-006, Regarding Mode Change Without B Channel Level Instrumentation Operable
05000454/LER-2012-003, Regarding Containment Area Radiation Monitors Inoperable for Longer than Allowed by Technical Specifications Due to Inadequate Procedure Controls
05000313/LER-2002-004, Arkansas Unit 1, Reactor Coolant System Pressure Boundary Leakage from a Fatigue Stress Crack of a Weld Connecting a Drain Line to a High Pressure Injection Line