05000400/LER-1987-008, :on 870227,loss of Main Feedwater & Automatic Start of Both motor-driven Auxiliary Feedwater Pumps Occurred.Caused by Transient in Turbine Load.Motor Replaced & Tested & Valve Returned to Svc
05000400/LER-1987-018, :on 870403,manual Reactor Trip Initiated Due to Loss of Both Main Feedwater Pumps.Caused by Inadvertent Short of Test Leads in Process Instrumentation Cabinet & Incorrect Setpoint.Undocumented Leads Removed
05000400/LER-1988-015-02, :on 880614,vent Stack Sample Not Obtained While Radiation Monitor Inoperable.Caused by Technician Involved W/Boron Sampling in Chemical & Vol Control Sys.Importance of Compensatory Sampling Stressed
05000400/LER-1989-022-01, :on 891210,loss of Operating RHR Train Occurred.Caused by Spurious Closure of Suction Valve During Testing of Interlocks.Procedure Revised to Ensure Breakers for Operating RHR Loop Open During Testing
05000400/LER-1987-049, :on 870925,operating Main Feedwater Pump Tripped on Low Flow.Caused by High Vibration in Recirculation Piping.Valve Stem Replaced & Recirculation Valve Returned to Svc on 870925
05000400/LER-1987-020, :on 870413,reactor Trip Setpoints on All Three Overtemp Delta Temp (Odt) Bistables Incorrectly Set.Caused by Apparent Design Oversight in Odt Circuit Design & Vendor Testing Methodology.Test Procedures Revised
05000400/LER-1990-012, :on 900415,Train a Emergency Bus Deenergized & Diesel Generator Automatically Started & Loaded Via Load Sequencer.Caused by Timing of Blocking Relay Actuating During Testing.Test Circuit Being Redesigned
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-1990-006, :on 900309,discovered That Evolution Violated Requirements of FSAR to Keep Individual Tanks Isolated from Another Tank.Caused by Failure to Address Evolution in Operating Procedure.Procedure Revised
05000400/LER-1990-015, :on 900524,concluded from Evaluation That Failure of Microswitch Contacts Could Prohibit Proper Sequencer Response to Safety Injection & Loss of Offsite Power Signals.Caused by Design Deficiency
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-1989-017-01, On 891009,generator & Main Power Transformer Phase Differential Relay Tripped Lockout Relay.Caused by Multiple Ground Faults.Design Changes & Repairs Being Conducted While Plant Performs Refueling
05000400/LER-1990-010, :on 900405,control of Reactor Auxiliary Bldg Emergency Exhaust Pressure Boundary Not Implemented.Caused by Lack of Administrative Controls for Doors & Hatches. Administrative Controls Implemented
05000400/LER-1989-017-03, :on 891009,turbine & Reactor Tripped Due to Generator & Main Power Transformer Phase Differential Relay Trip.Caused by Multiple Shorts to Ground.Design Changes & Repairs Being Conducted
05000400/LER-1989-013-01, :on 890814,technician Inadvertently Jumpered Contacts Starting Emergency Svc Water Booster Pump B.Caused by Personnel Error.Testing Stopped & Personnel Counselled on Attention to Work Activities
05000400/LER-1989-008-01, :on 890410,deficiencies Discovered in Testing of Thermal Overload Bypass Circuit for motor-operated Valve. Caused by Procedural Inadequacies Which Resulted in Insufficient Testing of Circuit
05000400/LER-1990-002-03, :on 891228,alarm for Quadrant Power Tilt Ratio Found Inoperable.Caused by Operator Reading Incorrect Scale. Calibr Performed.Addl Guidance Added to Alarm Response Procedure
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-1988-030, :on 881008,steam Generator Pressure in turbine- Driven Auxiliary Feedwater Pump Steam Supply Heater Noted. Caused by Inadequate Shift Turnover During Valve Repair During Outage.Valve Seated Properly
05000400/LER-1990-016, :on 900529,invalid Testing of Fuel Handling Bldg Emergency Exhaust Filtration Unit Occurred.Caused by Inadequate Location of Duct Flowrate Measurements.Test Procedure for Filtration Units Will Be Revised
05000400/LER-1989-003-02, :on 890206,shaft of Main Feedwater Pump a Sheared,Causing Sudden Reduction in Feedwater Flow to Steam Generators & Pump Trip.Caused by Corrosion in Shaft.Pump & Local Components Repaired
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-1988-011-01, :on 880511,Westinghouse Notified Plant of Unanalyzed Condition Re Inadvertent Actuation of Low Temp Overpressure Protection Sys.Automatic Actuation Function Disabled & Permanent Mod Under Consideration
05000400/LER-1988-026, :on 880831,cracking of Insulation on Wires & on Terminal Blocks in Top Works Portion of Valves Noted.On 880909 Concluded Valves Inside Containment Not Qualified for Harsh Environ Following Postulated Accident
05000400/LER-1989-002, :on 890117,water Inadvertently Drained from Spent Fuel Pool to New Fuel Pool.Caused by Incorrect Determination of Valves Position During Process of Removing Clearance.Spent Fuel Pool Level Restored
05000400/LER-1988-001, :on 880115,procedural Deficiency Which Could Have Resulted in Failure of ECCS During Recirculation Phase of Accident Identified.Caused by Failure to Note New Requirement in Procedure.Procedures Revised
05000400/LER-1988-001-02, :on 880115,emergency Operating Procedure (EOP) Deficiency for Switchover to Recirculation After LOCA Discovered.Caused by Failure to Incorporate FSAR Change Into Plant Procedures.Eops Revised
05000400/LER-1987-028, :on 870502,manual Turbine Trip Initiated During Performance of Power Ascension Test Procedure 9108-S-14. Caused by Tandem Trip of Both Heater Drain Pumps.Evaluation of Feedwater Response to Transients Continues
05000400/LER-1987-012, :on 870311,turbine & Reactor Trips Occurred During Troubleshooting at Main Turbine Supervisory Control Panel.Turbine Trip Caused by Depressing Test Push Button on Turbine Supervisory Control Panel
05000400/LER-1987-058, :on 871009,RCS Leakage Exceeded Tech Specs Limits When Valves in RCS Head Vent Sys Spuriously Opened During Testing.Caused by Inadvertent Opening of Down Stream Valves.Personnel Briefed on Design of Valves
05000400/LER-1987-038, :on 870622,high Steam Generator Water Level Turbine Trip & Main Feedwater Isolation Actuated Automatic Reactor Trip on Interlock.Caused by Sudden Increase in Electrical Load.Precautionary Measures Taken
05000400/LER-1987-017, :on 870331,reactor Trip Occurred Due to Steam Flow/Feedwater Flow Mismatch.Caused by Feedwater Control Valve Oscillation.Main Feedwater Regulating Valves Placed in Manual Control
05000400/LER-1987-057, :on 870929,deficiency in Surveillance Test Procedures Covering Diesel Generator Fuel Oil Transfer Pumps Revealed.Caused by Misinterpretation of Relief Granted by Nrc.Procedure Revised
05000400/LER-1987-036, :on 870621,air Roll of 1A-SA Diesel Engine Not Performed within 4 to 8 H After Engine Shutdown.Caused by Marking in Test Procedure Step as Not Applicable.Engine Air Rolled.No Accumulation of Water Detected
05000400/LER-1988-006, :on 880208,emergency Svc Water Sys Declared Inoperable.Caused by Isolation Valve Failures.Valves Repaired & Retested.On 880212,after Concern Raised,Manual Valve Closed,Pending Permanent Design Change