05000255/LER-1989-021-02, :on 890918,identified Possibility for Single Relay Failure Leaving Control Room HVAC Train in Normal Mode When Emergency Mode Would Be Desired.Switchover Circuitry Not Designed to Meet Single Failure Criteria
05000255/LER-1989-006, :on 890323 & 0516,concern Re Potential Complete Loss of Component Cooling Water (CCW) Following High Energy Line Break (HELB) Noted.Caused by CCW Sys Design Inadequacy. HELB Evaluation of CCW Sys to Be Performed
05000255/LER-1987-019-02, :on 870621,diesel Generator 1-1 & 1-2 Inadvertently Actuated While Personnel Attempted to Latch Turbine Generator.Caused by Failure of Autostop Oil Pressure Switch.Sop 8 Revised to Instruct Operations
NL-08-1906, LER 08-S01-00, for Edwin I. Hatch, Failure to Report Arrest Results in Inappropriate Access to Protected and Vital Areas
05000277/LER-1989-019-01, :on 890830,discovered That Five Doors Requiring Monthly Functional Tests,Per Tech Specs,Not Included on Surveillance Test.Caused by Deficiency in Methodology & Refs Used During Surveillance
05000331/LER-1989-006, :on 890224,isolation of RCIC & on 890302, Isolation of HPCI Occurred.Caused by Problems in Electrical Path from Thermocouples Monitoring Area Temp.Retermination of Broken Thermocouple Wire Before Break
05000334/LER-1998-018, :on 980409,inadequate Beaver Valley Power Station Procedures to Ensure Compliance W/Tech Specs Were Noted.Caused by Inadequate Training of Procedure Writers.Revised Procedures
05000318/LER-1998-005-01, :on 980725,initiated Plant Cooldown Due to RCS Pressure Boundary Leakage.Caused by Crack in Inconel Alloy 600-type Weld Filler Matl of Nozzle.Leaking Penetration Was Repaired from Outside of Pressurizer
05000454/LER-1996-014, :on 960903,failure to Comply W/Design Basis Re Sf Storage Racks Was Noted.Caused by Deterioration as Result of Improper Matl Selection.Controlled SFP Boron Concentration & Silica Concentration
05000336/LER-1998-015-01, :on 980504,channel Functional Testing of Digital Radiation Monitors Did Not Comply W/Ts.Caused by Inadequate Evaluation of Adequacy of Test Methodology. Procedure Changes Will Be Implemented
05000374/LER-1999-002-06, :on 990821,automatic Scram Occurred Due to Failure of Reactor Water Level Control.Caused by Inadequate Maint on 2A Tdrep Servo Valve 2FW163AA.Repaired Servo Valve
05000313/LER-1997-001, :on 970408,inconsistencies Between Once Through SG Tube Destructive Examination Were Noted.Caused by Morphology Differences Between Flaws Used to Develop Sizing Technique.Discretion Was Verbally Approved
05000482/LER-1997-017, :on 970930,spent Fuel Storage Facility Crane Surveillances Were Not Met.Caused by Inadequate Procedural Guidance.Spent Fuel Bridge Crane Declared Inoperable Until Procedure Revised
05000327/LER-1985-019-01, :on 850524,inadequate Seismic Piping Supports Discovered.Caused by Personnel Errors.Drawing Discrepancies Re Both Pipes Corrected & Sk Series of Prints Superseded by 47W Series of Prints
05000219/LER-1998-016, :on 981028,single DG Start,Occurred.Caused by Loss of One Source of Offsite Power.Generator Relay Surveillance Revised to Eliminate Possibility of Inadvertent Procedural Breaker Trips.With
05000325/LER-1999-004-01, On 990325,drywell Pressure Instrumentation Sensing Line Deficiency,Was Determined.Caused by Incorrect Design & Installation of Instrument Sensing Lines.Associated Sensing Lines Were Purged.With
05000412/LER-1999-001-01, :on 990227,failure to Comply with TSs Due to Not Meeting Acceptance Criteria for Source Range Monitor During Surveillance Testing,Was Discovered.Caused by Lack of Attention.Procedure 20ST-2.3 re-performed.With
05000456/LER-1997-008-06, :on 971010,determined That Projected SG leak- Rate Combined W/Ts Limit for Dose Equivalent Iodine Creates Potential for Operation Outside Design Basis.Caused by Density Correction.Sgs Replaced
05000293/LER-1998-022, :on 981002,unplanned Actuation of a EDG Occurred During Surveillance Test of Related Logic Sys Testing.Caused by Util non-licensed I&C Technician Error. Will Review Surveillance Procedures.With
05000250/LER-1998-005-02, :on 980924,suspended Safeguards During Severe Weather Due to Personnel Safety.Caused by Severe Weather Associated with Effects of Hurricane Georges.Fully Instituted Compensatory Measure.With
05000373/LER-1998-015-02, :on 980819,manual Reactor Scram Occurred Following Level Control Transient.Caused by Failure of Control Card Associated with Bailey Rwl Cs.Replaced Failed Card with Refurbished Unit.With
05000366/LER-1997-004-02, :on 970331,inaccurate List of Primary Containment Isolation Valves Resulted in Missed Surveillance.Caused by Listing of PCIS Valve Position Indications.Performed Missed Surveillance
05000409/LER-1985-019, :on 851026,partial Reactor Scram Occurred Due to Momentary Short in CRD Gas Pressure Circuit.Caused by Worn Mechanical Seal Allowing More Seal Water to Flow Through than Normal.Seal Leakage Reduced
05000346/LER-1985-016, :on 850802,determined That Strainers Still Installed in Suction Piping of HPI Pumps Not Considered in Operating Design.Caused by Failure to Remove Strainers Following Const.Strainers Removed
05000354/LER-1995-033-01, :on 951114,TS Surveillance Requirement Implementation Deficiencies Occurred.Caused by Lack of Documentation of Annunciation for Previous Surveillances. SDV Bypass Logic Were Satisfactorily Tested
05000382/LER-1992-018-01, :on 920930,loss of 3A3-S Safety Bus Experienced When Bus Feeder Breaker Tripped Open on Degraded Voltage Condition.Caused by Personnel Error.Design Change Package Implementation Process Will Be Revised
05000213/LER-1985-016, :on 850703,ex-core Channel Failed to Meet Acceptance Criteria for Dropped Rod Load Runback Setpoint During Nuclear Instrumentation Sys Surveillance.Caused by Setpoint Drift.Setpoint Recalibr
05000413/LER-1985-054, :on 850906,08,11 & 17,containment Noble Gas & Iodine Radiation Monitors EMF39 & EMF40 Tripped.Caused by Increased Containment Activity Due to Fuel Rod Cladding Leaks.Monitor Setpoints Revised
05000285/LER-1996-014, :on 961117,reactor Cooldown in Excess of Limits Occurred Due to Starting Reactor Coolant pumps.OP-2A & OI-RC-9 Will Be Revised
05000213/LER-1985-023, :on 850823,determined That Fire Protection Valves FP-V-231 & 234 Not Properly Tested.Caused by Misinterpretation of Tech Spec Requirements.Surveillance Procedure Sur 5.5-24 Revised
05000317/LER-1992-007, :on 921112,discovered Concern Re Shutting of ECCS min-flow Isolation Valves SI-659 & 660.Caused by Procedural Deficiency.Procedures & Testing Revised
05000302/LER-1992-026, :on 921208,replacement of Failed RCS Flow Transmitter Caused Voluntary Entry Into TS 3.0.3.No Corrective Actions Planned
05000302/LER-1992-023, :on 921110,oversight Discovered in Original App R Analysis Results in Operation Outside Design Basis. Analysis Failed to Realize That MUV-31 Could Fail While closed.MUV-31 Scenerio Reanalyzed
05000423/LER-1996-013-02, :on 960515,determined Design Deficiency in Residual Heat Removal System (Rhs).Caused by Original Plant Design.Corrective Actions Will Be Described in Supplement
05000423/LER-1996-007-01, :on 960403,CRS & Qs Sys Found Outside Design Basis Due to Design Errors.Restored Sys to Appropriate Design Basis Requirements Prior to Declaring Sys Inoperable
05000353/LER-1996-002-02, :on 960315,ESFA Occurred Due to Loss of Power to Rps/Ups Power Distribution Panel.Caused by Inadvertent Actuation of Underfrequency Relay.Created Necessary Addl Physical Barriers Arounds Units 1 & 2
05000338/LER-1996-002, :on 960303,containment Particulate & Gaseous Radiation Monitors Inoperable.Caused by Inadequate Review of Containment Gaseous & Particulate Radiation Monitor. Suppl & Exhaust MOVs Shut
05000373/LER-1995-015-02, :on 950824,TS Fire Protection Valve Surveillance Was Missed Due to Insufficient Review of TS Fire Surveillance During Mod Process.Implemented Fire Watch in Unit 1 Csr
05000373/LER-1995-014-02, :on 950816,reactor Scram Occurred Due to 1D RPS Trip Causing Group 1 Isolation.Upgrade Model of EPM Assembly Logic Cards Installed on Both Unit 1 RPS Motor Generator Sets & Upper Main Steam Tunnel Switches Calib
05000354/LER-1995-030, :on 951106,FRVS Noble Gas Surveillance Was Missed Due to Personnel Error.Revised Procedure
05000301/LER-1995-004-01, :on 951026,inadvertent ESF Actuation Occurred as Result of Improper Relay Alignment.Assigned Addl Technician to Concurrently Check Proper Removal & Installation of Remaining Relays
05000325/LER-1992-003, :on 920117,reactor Scrammed Due to Primary Uninterruptible Power Supply (UPS) Internal Failure.Standby UPS Placed in Svc Prior to Reactor Startup & Addl Troubleshooting to Be Conducted on Primary UPS
05000287/LER-1984-004-02, :on 840607,w/unit at 20% Power,Turbine Generator/Reactor Anticipatory Trip Occurred.Unit Stabilized at Hot Shutdown Conditions.Cause Unknown.Unit Restarted & Reached 100% Power on 840609
05000352/LER-1995-002-01, :on 950221,dual Unit Scram Occurred Due to Offsite Electrical Transmission Disturbance.Changed Ground Fault Detection Relay Setttings for LGS Units 1 & 2 Main Transformers to Provide Better Coordination W/Sys Equipment
05000301/LER-1995-003, :on 950307,turbine Runback & RT Resulted from Oil Leak & Subsequent Pressure Loss in Unit 2 Turbine Generator Eg Control Sys.Attempted to Tighten Union Joint & Maintained Level in Eg Oil Reservoir
05000348/LER-1995-003, :on 950206,determined That Train a of Ssps Potentially Susceptible to Failure in Event of Postulated High Energy Steamline Break.Caused by Spss Design. Maintenance/Surveillance Activities Restricted
05000373/LER-1995-002-05, :on 950208,Unit 1 Reactor Shutdown Commenced Due to Inability to Isolate Inboard Steam Supply to Rcic. PCIS Valve 1E51-F063 Declared Inoperable & Outboard Isolation Valve 1E51-F007 Closed & Deactivated
05000321/LER-1994-013, :on 941103,false Low Turbine Speed Signal Resulted in Inoperable HPCI Sys.Caused by Failure or Misadjustment of Turbine Magnetic Speed Pickup.Magnetic Speed Pickup Replaced
05000456/LER-1994-012-03, :on 940811,experienced Inadvertent Main Steam Line Isolation at Power Due to Equipment Failure.Failed A516 Ssps Safeguards Output Driver Circuit Board & A315 Universal Logic Circuit Board Replaced
05000324/LER-1991-001-02, :on 910125,reactor Scram Occurred from 100% Power Due to Turbine Trip on High Reactor Water Level While Calibrating Feedwater Computer Point.Caused by Failure of Work Control Process.Calibrs Stopped
05000368/LER-1991-009, :on 910311,containment Ventilation Sys Effluent Pathway Not Being Monitored for Particulate & Iodine Activity Due to Personnel Error.Disciplinary Action Taken Against Responsible Individual
05000266/LER-1994-003, :on 940217,reactor Coolant Sys Sample Line Declared Inoperable & Isolated.Caused by Failure of SC-955 as Result of Loss of Coolant Accident.Penetration P-28a on Units Isolated
05000298/LER-1994-003, :on 940215,TS Violations Occurred Due to Inoperable Radiation Monitors.Caused by Improperly Assembled Particulate/Iodine Filter Assemblies.Missing O-rings Replaced & Leak Test Conducted
05000266/LER-1994-001, :on 940208,automatic Actuation Feature of Halon Fire Suppression Sys for Afp Room & Vital Switch Room Disabled.Caused by Personnel Error.Hourly Fire Rounds Performed Until Halon Restored to Svc,
05000282/LER-1993-014, :on 931116,determined Control Cables for Redundant Pressurizer Porvs,Found Touching,Violated Criteria for Physical Separation of Cables.Cables Repositioned & Secured
05000293/LER-1993-018, :on 930721,planned Shutdown Initiated Due to Unidentified Leakage of 3 Gpm.On 930722,planned Shutdown Became TS Required Shutdown When Insp Revealed Leakage to Be Rc Pressure Boundary Leakage.Leakage Repaired
05000369/LER-1993-007-01, :on 930705,TS Required Surveillance Was Not Performed Because of Inappropriate Action Because of Lack of Attention to Detail.Generated WO 93047633 to Perform Required Surveillance on Unit 1 IPE CA 9010
05000298/LER-1993-014, :on 930316,small through-wall Leak Developed on High Pressure Side of SW Throttle Valve.Caused by Inadequate Valve Design.Frequency of Visual Insp of Valve Internals Will Be Increased to Once Per Cycle
05000245/LER-1993-003-02, :on 930426,discovered That Primary Containment Penetration X-25/202D Exceeded Max Allowed TS Leakage.Caused by Slightly Worn Seat Ring & Plug in Valve Not Fully Seating.Seat Ring Replaced
05000280/LER-1988-038, :on 880928,three Recirculation Spray HXs Filled W/Svc Water Discovered.Caused by Leakage Past Normally Closed Recirculation Spray HX Inlet Isolation Valves.Samples Taken
05000280/LER-1987-029, :on 871108,main Control Room Ventilation Isolated Due to High Voltage Output on Chlorine Detector. Caused by Increased Voltage Output Inducing Spurious Signal.Ventilation Sys Realigned
05000255/LER-1988-003-01, :on 880221,23 & 24,secondary Side Contents of Steam Generators E-50A & E-50B Discharged to Lake Michigan as Continuous Release.Samples Disposed of Prior to Required Analyses.Caused by Procedure Deficiency
05000255/LER-1988-007, :on 880429,auxiliary Feedwater Actuation Sys Actuated.Caused by Surveillance Procedure RO-21 Inadequacy That Permitted Input of Test Signal to Result in Quick Open Signal Generation.Procedure Corrected & Tested
05000255/LER-1987-037, :on 871106,licensee Failed to Take Compensatory Measures During Temporary Loss of Fire Suppression Sys. Caused by Misleading Plant Diagram.Change Request Initiated to Correct Misleading Diagram
05000255/LER-1987-035, :on 871015,LPSI Pump P-67A Manually Secured from Operation Due to Erratic Discharge Pressure & Flow. Caused by Improperly Placed Jumper.Review of Requirements & Controls on Work Planning Process in Progress
05000255/LER-1987-030, :on 870903,QA Personnel Identified That Safety Injection tank,T-82B (Bp;Tk),Not Being Sampled for Boron Concentration at Frequency Specified in Facility Tech Specs. Tech Spec Change Request Submitted on 870911
05000255/LER-1987-038, :on 871022,auxiliary Operator Had Worked 28 H in 48 H Period,Exceeding Work Hour Limitations.Caused by Operator Unfamiliarity W/Overtime Limitation Criteria.Memo Issued as Part of Required Reading Program
05000255/LER-1987-009, :on 870325,auxiliary Feedwater Sys Actuation Signal Received Due to Low Water Level in Steam Generator. Caused by Shrinkage of Steam Generator Level During Testing. Personnel Informed of Circumstances of Event
05000296/LER-1997-001-04, :on 970305,loss of Offsite Power on Unit 3 During Refueling Outage Resulted from Shorted Component. Replaced Relays Involved in Event W/Less Sensitive Relays
05000400/LER-1987-056, :on 870924,reactor Tripped Due to Deenergization of P-13 Permissive Bistable.Caused by Personnel Error Due to Insufficient Instructions.Procedure for Mod Implementation Revised
05000400/LER-1987-037, :on 870621,manual Reactor Trip Initiated from 30% Power After Operating Main Feedwater Train Tripped. Caused by Failed Open Feedwater Pump Recirculation Valve. Circuit Repaired & Plant Returned to Svc
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
05000251/LER-1987-015-01, :on 870715,technicians Failed to Deactivate Inoperable Containment Isolation Valve within 4 H as Required by Tech Specs.Caused by Personnel Error.Procedure Completion Responsibility Centralized
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
05000251/LER-1987-011-02, :on 870608,automatic Actuation of Component Cooling Water Pump 4C Occurred.Caused by Low Sys Pressure Due to Leak in 4A Component Cooling Water Hx.Hx Removed from Operation & Leak Repaired
05000315/LER-1994-012, :on 941205,noted That Vent Stack Particulate Filter Gamma Spectrum Results for 941130 Not Available for Review Due to Personnel Error.Backup Sample Analyzed & Evaluated
05000397/LER-1991-024, :on 910909,unanalyzed Condition Associated W/ Postulated Main Steam Line Failure Outside Containment Discovered by Ge.Caused by Failure to Consider Iodine Source Term.Procedure Re Cold Startup Changed
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
05000335/LER-1998-009, :on 981223,noted That Facility Operated Outside of Design Basis.Caused by non-conservative MSLB Analysis Inputs.Will Review SR Component Differences Between Units & Will re-baseline LTOP Analysis.With
05000454/LER-2012-003, Regarding Containment Area Radiation Monitors Inoperable for Longer than Allowed by Technical Specifications Due to Inadequate Procedure Controls
05000219/LER-1998-002-01, :on 980227,480 V Switchgear Room Fire Barrier Deficiency Was Noted.Caused by Inadequate Fire Barrier Spec. Two of Seven Fire Zones Where Conduit Fire Barriers Are Installed Were Reviewed,No Deficiencies Found
05000219/LER-1998-003-01, :on 980303,failure to Perform High Drywell Pressure Check Surveillance Was Noted.Caused by Inadequate Procedure.Reviewed & Revised Appropriate Plant Documents & Provided Operator Training
05000461/LER-1998-011, :on 980312,CR Ventilation Sys Was Declared Inoperable Due to Broken/Missing Conduit Hold Down Restraints on VC Chiller Skids.Caused by Personnel Walking on Equipment.Generated Work Requests
05000334/LER-1998-028, :on 980811,reactor Trip Occurred.Caused by Cognitive Error by Involved Licensed & non-licensed Shift Operating personnel.F-MS-475 Repaired & Returned to Svc. with
05000382/LER-1997-012, :on 970404,programmatic Breakdown of Overtime Program Occurred.Caused by Lack of Mgt Oversight in Administering & Implementing Plants Working Hour Policy. Ltr Issued Reemphasizing Working Hour Policy
05000331/LER-1994-013, :on 941111,reactor Water Cleanup Sys Isolation Due to Failed Head Gasket on Filter Demineralizer 1T203A. Insp of Flange & Closure Bolts on 1T203A Filter Demineralizer Revealed No Damage
05000219/LER-1994-013, :on 940726,TS Shutdown Margin Limit Exceeded Due to HCU 06-19 Being Tagged Out of Svc W/Associated CR in Full Out Position.Caused by Human Error.Hcu Returned to Svc & CR Fully Inserted