05000285/LER-1993-011, :on 930624,experienced Reactor Trip Due to Loss of Load.Caused by Lack of Proper Job Planning,Lack of Formal Decision Making Process & Incomplete Communications.Training Will Be Provided to Operations Personnel
05000317/LER-1988-014, :on 881029,while Performing Surveillance Test Procedure to reverse-flow Test Check valves,MS-103 Leaked By.Caused by Excessive Cycling Due to leak-by of MS-102. Check Valve MS-103 Replaced W/Identical Valve
05000259/LER-1998-001-03, :on 980414,standby Gas Treatment Sys HEPA Filter Testing Was Not in Compliance W/Ansi Std Requirements.Caused by Lack of Understanding of DOP Testing. Filter Testing Training Will Be Provided
05000311/LER-1989-006-02, :on 890329,reactor Trip Signal on Steam Generator 21 Occurred After Shutdown for Compliance W/Tech Spec Action Statement 3.7.7.b.Caused by Equipment Problems. Channel I Transmitter Recalibr
05000416/LER-1989-001, :on 890327,power Interruption to ESF Bus Caused Secondary Containment Isolation.Div 1 Bus Connected to ESF Transformer 12 to Provide Div 1 & 2 Buses W/Independent Power Sources
05000483/LER-1987-004, :on 870404,while in Mode 5 Cold Shutdown, Release of Primary Coolant to Containment Environ Occurred. Caused by Inadequate Spec of Type of Connection to Be Used Between Pressurizer & Pressurizer Relief Tank
05000306/LER-1986-004, :on 860801,electrician Opened Switch for Circuit 2 on Dc Panel 21 to Isolate Ground to Single Circuit,Causing Auxiliary Feedwater Pump to Start.Caused by Personnel Error.Personnel Counseled
05000213/LER-1986-028-01, :on 860610,switchgear Room Halon Sys Declared Inoperable.Caused by Failure to Perform Adequate Retest. Completion of long-term Corrective Mod Deferred Until 1987 Refueling Outage
05000327/LER-1986-024, :on 860525,security Micro Access Computer Malfunctioned,Locking All Security Access Doors.Caused by Complete Loss of Access Memory.Backup Battery Replaced & Disk Drive Unit Cleaned
05000483/LER-1986-035, :on 860928,containment Purge & Control Room Ventilation Isolation Occurred After Monitor GT-RE-32 Taken Out of Bypass.Caused by Random Fluctuations of Radioactivity Level.Plant Procedures Revised
05000382/LER-1987-003, :on 870122,radiation Monitor Alarmed Due to Contaminated Instrument & Controls (I&C) Technician.Caused by Health Physics Technician Improperly Downgrading Work Permit Requirements.I&C Technician Retrained
05000374/LER-1986-009-05, :on 860511,w/synchronization to Grid at 15% Power,Primary Containment Isolation Sys Group I Isolation Occurred.Caused by Main Steam Line High Flow Signal.Main Steam Line Piping Walked Down.No Leaks Found
05000263/LER-1986-010, :on 860508,reactor Bldg Ventilation Isolation & Standby Gas Treatment Sys Initiation Occurred.Caused by Reactor Bldg Vent wide-range Gas Monitor Trip Due to Hardware/Software Problems
05000220/LER-1986-006, :on 860409,discovered That One of four-inch Sample Lines to Header Completely Plugged.Caused by Pebbles Washed Off Reactor Bldg Into Roof Drains.Roof Drain Screens Will Be Installed
05000366/LER-1986-018-01, :on 860810,RWCU Sys Isolated on High Differential Flow Signal.Caused by RWCU Resin Trap Not Being Filled & Vented Prior to Placing Sys in Svc or Resin Trap Isolation Valves Being Open.Procedure Modified
05000263/LER-1986-020, :on 860619,reactor Protection Sys (RPS) & Group II Tripped from Loss of Power.Caused by RPS-B Power Supply Being Fed from Alternate Power Source as Same Load Ctr Source as RPS-A
05000324/LER-1987-004-02, :on 870311,reactor Scram on Low Level Due to Loss of Uninteruptible Power Supply & Subsequent Loss of Feedwater.Caused by Noncompliance W/Procedure to Transfer Power.Motor Replaced & Sys Returned to Normal
05000286/LER-1986-005-01, :on 860523,turbine Trip Occurred During Monthly Surveillance Test 3PT-M12.Caused by Failed Relay in Turbine Independent Electrical Overspeed Protection Sys (Ieops). Relay Replaced & Similar Ieops Relays Tested
05000327/LER-1986-010-01, :on 860406,fuse Inadvertently Dislodged, Starting Diesel Generators 1A-A & 2A-A.Caused When Assistant Unit Operator Attempted to Verify Fuse Size.Procedure Will Be Revised to Add Caution Re Fuse Removal
05000315/LER-1986-014-01, :on 860628,surveillance Testing Not Performed to Meet Requirements of Tech Spec 4.5.2.d.1 to Verify Interlock Action of RHR from Rcs.Caused by Personnel Error. Procedures Written to Ensure Compliance
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
05000247/LER-1986-007, :on 860307,plant Heated Above 200 F Although Listed Transmitters Not Resealed,Per Environ Qualification Requirements.Caused by Not Recognizing Environ Status Should Have Been Restored.Procedures Reviewed
05000263/LER-1986-016, :on 860611,both Squib Valve Detonators Shorted After Firing & Control Power Transformer Fuse Blew,Causing Pump Motor Trip.Caused by Improper Fuse Coordination.Fuse Coordination Corrected
05000261/LER-1986-008-02, :on 860307,determined That Test Procedure Omits Exercising Station Blackout Relays in Automatic Feedwater Pump Logic.Cause Unknown.Procedure OST-162 Will Be Revised to Ensure Components Tested
05000321/LER-1986-017, :on 860415,LPCI Outboard Primary Containment Isolation Valve Isolated Causing Shutdown Cooling Capability Loss.Caused by Blown Fuses from Inadvertent Short of Relay Contacts Due to Personnel Error.Valve Reopened
05000316/LER-1986-002, :on 860122,discovered That 4 H Surveillance Frequency Exceeded on Four Occasions Between 851023-26.Cause Attributed to Lack of Procedural Control.Procedural Requirements Implemented
05000324/LER-1985-011, :on 851015,reactor Pressure Spiked & Unit Auto Scrammed on High Power When MSIV B21-FO22a Auto Closed. Caused by Failure of three-way Solenoid Valve Assembly.Valve Assembly Replaced
05000321/LER-1985-047, :on 851220,use of GE Silicone Sealant (RTV-102) on Both Drywell Personnel Airlock Doors Prevented Adequate Leak Rate Testing of Door Seals.Caused by Personnel Error. New Seals Installed
05000237/LER-1986-004-05, :on 860217-20,core Thermal Power Limit Violated for 41 H.Caused by Reactor Feedpump 2C Flow Transmitter Out of Calibr.Work Request Issued to Install Protective Barrier Around Transmitter
05000382/LER-1985-044, :on 851010,uncomplicated Reactor Trip Occurred. Caused by High Water Level in Steam Generator 2 When Control Board Operator Increased Feedwater Flow to Steam Generators. New Guidelines Issued
05000369/LER-1985-036-01, :on 851119,reactor Tripped Due to Feedwater Pump Turbine Trip on High Discharge Pressure.Caused by Rod Control Sys Not Lowering Power Enough During Turbine Runback.Failed Fuse Will Be Replaced
05000387/LER-1985-023, :on 850611,manual Isolation Valve 141005 Found Open.Caused by Inability to Perform Required Surveillance Testing on Excess Flow Check Valve XV-141F009.Procedures Revised
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
05000275/LER-1985-024, :on 850712,temporary Change to safety-related Procedures Not Reviewed by Plant Staff Review Committee & Approved within 14 Day Tech Spec Time Limit.Caused by Change in Processing Procedure
05000293/LER-1997-001, :on 970120,very Small Quantity of Unaccountable Special Nuclear Material Was Identifed Due to Less than Effective Methods for Control & Accounting of Devices. Procedures Revised
05000295/LER-1985-016-05, :on 850731,operator Accidentally Tripped Over & Broke Off Control Air Line to Fire Protection Containment Isolation Valve 1FCV-FP08.Broken Air Line Repaired & Valve Returned to Position
05000397/LER-1985-052, :on 850801,discovered Procedure Deviation Issued on 850608 Incorrectly Changed Containment Isolation Valve Closure Time.Procedure Mod Issued
05000213/LER-1985-018, :on 850725,fire Door from Svc Bldg to Diesel Generator a Room Inoperable Due to Security Hardware Repairs.Fire Watch Not Posted Due to Confusion Over Operability Requirements of Fire Doors
05000318/LER-1985-008-01, :on 850724,MSIV Failed to Fully Close & Declared Inoperable.Caused by Oil Deficiency Due to Gas Bubble in Hydraulic Fluid Header & Addl Component Malfunctions.Suppressor Bladders Replaced
05000327/LER-1984-045, :on 840625,auxiliary Control Air Compressor A-A Taken Out of Svc.On 840709,compressor B-B Removed from Svc. Power Reduction to Mode 3 Initiated But Stopped When Compressor B-B Returned to Svc
05000304/LER-1985-013-07, :on 850707,steam Generator Blowdown Radiation Monitor 2RE0019 High Alarmed,Causing Isolation of Blowdown. Notice Issued to Operating Dept Reiterating Proper Procedures
05000321/LER-1985-032, :on 850918,quarterly Surveillance Test for Drywell Main Exhaust Inboard Isolation Valve T48-F319 Not Performed Per Tech Specs.Caused by Personnel Error.Limiting Condition for Operation Initiated
05000382/LER-1985-032, :on 850704,reactor Trip Occurred Due to Axial Shape Index Being Out of Range Allowed by Core Protection Calculator.Caused by Xenon Distribution.Plant Operators Given Temporary Guidance on Returning Power
05000260/LER-1985-010-04, :on 850626,inadvertent Secondary Containment Isolation Occurred Due to Failure of Fuse in Panel 9-42. Cause Not Determined.Blown Fuse Replaced.Isolation Signal Reset.Failure Considered Random
05000382/LER-1985-026, :on 850626,small Opening Discovered in Penetration of Emergency Diesel Generator B Room Fire Wall. Condition Thought to Exist Since Const of Fire Wall.Fire Watch Posted & Wall Repaired
05000366/LER-1985-019-01, :on 850429,during Cold Shutdown,Reactor Water Cleanup Primary Containment Inboard Isolation Valve 2G31-F001 Isolated.Caused by Personnel Error.Resistance Temp Detectors Relabeled
05000219/LER-1984-024, :on 841027,one of Two Switches Associated W/ Reactor lo-lo Water Level Sensor RE02C Failed to Trip at Setpoint Required by Procedure.Core Spray Instrumentation Channel Test Procedure Revised
05000275/LER-1985-016, :on 850520,automatic Reactor Trip Occurred. Caused by Deenergization of Bistables for Source Range Channel 32 (Jc)(Ri) Due to Voltage Transient.Event Reviewed W/Applicable Personnel & Procedure Revised
05000382/LER-1985-018, :on 850511,unidentified Leakage Noticed.Leak Originated in Packing Glands of Pressurizer Spray Valves RC-301A,B.Packing Glands Modified
05000293/LER-1996-005, :on 960419,automatic Scram Occurred Due to Turbine Vibration During Planned Power Reduction.Turbine Vibration Trip Setting That Initiates Trip of Turbine Due to High Vibration Changed
05000416/LER-1985-015, :on 850404,RCIC Sys Inadvertently Isolated When Bypass Switch Mistakenly Returned to Normal During Testing.Caused by Misunderstanding Between Personnel.Sys Restored.Need for Clear Communication Stressed
05000387/LER-1984-011, :on 840301,two Initiations of Control Room Emergency Outside Air Supply Sys & Standby Gas Treatment Sys Occurred.Caused by Voltage Drop & Incorrect Removal of Test Jumper Cables
05000366/LER-1985-009-01, :on 850319,RCIC Steam Supply Primary Containment Inboard Isolation Valve 2E51-F007 Inadvertently Closed.Caused by Personnel Error.Isolation Logic Reset & Valve Returned to Open Position
05000265/LER-1985-009-07, :on 850320,fuel Pool Radiation Monitor 2A Tripped.Caused by Transfer of Steam Dryer from Reactor Cavity to Dryer Separator Storage Pit Due to Procedural Inadequacy.Procedures Being Revised
05000483/LER-1984-064, :on 841217,reactor Trip Received on Rapidly Decreasing Pressurizer Pressure.Caused by Lifting of PORVs & Fully Opened Pressurizer Spray Valves.Test Procedure Revised & Test Repeated Successfully
05000280/LER-1984-025, :on 841203,during Refueling Outage W/Plant in Cold Shutdown,Source Range & Intermediate Range Trip Signal Occurred.Caused by Voltage Transient Induced Upon Vital Bus 2 During Replacement of Key Switch
05000483/LER-1984-039, :on 840915,analog Channel Operational Test of Load Shedder & Emergency Load Sequencer Failed Due to Lack of 48-volt Dc Output from Undervoltage Power Supply Assembly.Channel Placed in Tripped Position
05000373/LER-1996-001-06, :on 960213,missed TS Required Fire Protection Valve Position Verification Occurred.Caused by Human Performance.Operating Dept Senior Mgt Reinforced Expectations W/Sros & Shift Supervisors
05000366/LER-1984-031, :on 841031,reactor Water Cleanup Inboard Isolation Valve 2G31-F002 Isolated Due to High Equipment Room Temp.Caused by Pump Shaft Seal & Two Pump Vent Valves Leaking.Seal Replaced & Valves Repaired
05000366/LER-1984-016, :on 840815,spurious LOCA Signal Initiated Four RHR Pumps,Two Core Spray Pumps,Three Diesel Generators & HPCI & Rcic.Caused by Personnel Error in Completing Procedure Data Package
05000327/LER-1984-052, :on 840817,during Review of Procedure SI-144.2, Control Room Emergency Ventilation Sys Test, Discovered That Incorrect Calculation of Duct Area Resulted in Both Trains of Sys Left Lower than Specs
05000354/LER-1995-040, :on 951218,EDG B Inadvertently Started Due to Improper Removal from Svc.Caused by Lack of Questioning Attitude by Operations Personnel.Addressed Communications Issues & Made Procedural Revs
05000321/LER-1984-015, :on 840803,reactor Scram Received on Turbine Control Valve Fast Closure Subsequent to Generator Load Rejection.Caused by Component Failure.Safety Relief Valve a Top Works Will Be Replaced
05000456/LER-1995-019-03, :on 951207,manual Reactor Trip Initiated During Rod Drop Testing Due to Failed Testing Relays.Reactor Trip Breakers Opened
05000374/LER-1995-010-04, :on 951007,Unit Two Fire Door 615 Was Left Open Due to Personnel Error.Reviewed Fire Impairment Log & Was Determined No Active Fire Impairment for Fire Door 615
05000348/LER-1995-008, :on 950916,loop a Main Steam Line Isolation Valves (MSIV) Failed to Close Due to Personnel Error.Loop a MSIVs Vented & Closed,Test Procedure Modified & Operator Coached on Event
05000348/LER-1995-007-01, :on 950927,discovered That Control Room Pressurization Units Moisture Controllers Incapable of Performing Intended Function Due to Procedural Inadequacy. Established Repetitive PM Tasks
05000327/LER-1984-040, :on 840608,Tech Spec Surveillance Requirement for Standby Diesel Generator Overspeed Trip Lockout Not Performed within Required Time.Caused by Erroneous Rev to Procedure.Procedure Revised Correctly
05000280/LER-1984-012-01, :on 840526,specific Activity Sample of Reactor Coolant Showed Peak Dose Equivalent I-131 Level of 1.57 Uci Which Exceeded Tech Spec Limit.Caused by Fuel Element Defects in Reactor Core.Dose Equivalent Monitored Every 4 H
05000369/LER-1984-004-01, :on 831117,source Leak Test Not Performed Prior to Installation of in-core Detector.Caused by Personnel Error & Procedure Not Requiring Signature Signoff.Procedure Revised to Require Signoff
05000328/LER-1984-003-05, :on 840227,vital Inverter Failed.Caused by Blown Fuse Due to Incorrect Connection Which Caused Containment Ventilation Isolation.Containment Ventilation Isolation Reset & Inverter Returned to Svc
05000251/LER-1984-002-02, :on 840212,reactor Trip Occurred Due to Steam Flow Greater than Feed Flow Coincident.Caused by High Steam Flow Reading on Steam Generator 4A.Calibr Check Performed
05000327/LER-1984-027, :on 840420,high Radiation Alarm Actuated, Causing Containment Ventilation Isolation to Occur.Caused by Voltage Spike Due to Electromagnetic Interference.Alarm Reset & Monitor Returned to Svc
05000348/LER-1984-005, :on 840409,reactor Tripped Due to Low Level in Steam Generator 2A in Conjunction W/Loop 1 Steam Flow Greater than Feed Flow.Caused by Operator Error During Performance of FNP-2-STP-33.1.Relay Replaced
05000336/LER-1995-004, :on 950131,TS Surveillance for Liquid Waste Radiation Monitor Was Missed Due to Personnel Error. Performed Surveillances to Satisfactory Completion on Following Day
05000327/LER-1984-003-02, :on 840120,high Radiation Alarm Actuated, Causing Containment Ventilation Isolation to Occur.Caused by Electromagnetic Interference.High Radiation Alarm Reset & Monitor Returned to Svc
05000416/LER-1984-012, :on 840314,discovered That Verification of Closed Fire Doors Once Every 24 H Did Not Include Elevator Doors.Caused Not Stated.Surveillance Revised to Include Elevator Doors
05000458/LER-1995-005-02, :on 950627,HPCS Pump Breaker Tripped During Surveillance Testing.Cause of Failure Not Identified.Breaker Internals,Prop Springs & Closing Latch Spring Inspected.W/
05000285/LER-1993-014, :on 930926,PORV PCV-102-1 Inadvertently Opened During Test.Caused by Improper Valve Maint During 1984 Mod. C/A:Pcv Refurbished & Tested
05000412/LER-1988-005-01, :on 880219,startup Feedwater Pump Started, Causing Current Surge That Actuated Overcurrent Relay for Emergency Response Facility Transformer 3B.Caused by Faulty Transformer Relay.Relay Replaced
05000338/LER-1993-013, :on 930414,identified Addl Missed Surveillance to Functionally Test Entire Circuitry for Manual Phase a Isolation Switches.Caused by Personnel Error.Periodic Test Procedures Will Preclude Recurrence
05000237/LER-1981-025-03, /03L-0:on 810518,during Plant Tour by Operations Personnel,Low Pressure Leg of Isolation Condenser Level Indication Found Valved Out.Probably Caused by Valve Not Being Reopened After Sampling.Valve Opened
05000315/LER-1987-004, :on 870408,unit Shut Down Due to Unidentified RCS Leakage Per Tech Spec 3.4.6.2.Caused by Leakage Greater than 1 Gpm from Letdown Isolation Valve.Leakage Sources Repaired
05000220/LER-1986-005, :on 860402,during Shutdown for Refueling,Full Scram Experienced.Caused by Loss of Power to Reactor Protection Sys Bus II Due to Deenergization of Brown Boveri ITE-27 Relay.Relay Repaired or Replaced
05000387/LER-1984-042, :on 840926,significant Operating Occurrence Rept Written,Detailing Occurrences Between 831223-840329 When Chemistry Samples Not Taken within Specified Time Limits
05000370/LER-1984-009, :on 840319,reactor Trip Initiated by Steam Generator a low-low Level.Caused by Sys Fluctuations After Loop Power Supply Card Failed.Nlp Card Replaced & Loop Returned to Svc