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| Issue date | Title | Topic | |
|---|---|---|---|
| ML20029D657 | 6 May 1994 | LER 94-005-00:on 940407,chain Locking Mechanism on CP Suction Isolation Valve,Was Found Broken.Caused by Personnel Error.Corrective Action:New Chain Placed on Valve Handwheel & Chain Locking Mechanism intacted.W/940506 Ltr | Probabilistic Risk Assessment |
| ML20029D803 | 4 May 1994 | LER 94-003-00:on 940404,two Flow Orifices Were Improperly Installed.Caused by Improper Installation of All Accessible Flow Orifices.Personnel Performed Procedure Ost 1.6.4 Correcting Improperly Installed orifices.W/940504 Ltr | |
| ML20046B548 | 30 July 1993 | LER 93-012-00:on 930702,discovered That Hydrogen Analyzer Inoperable During Quarterly Performance of Calibration Procedure.Test Personnel Contributed to Cause of Event.Test & Calibration Procedures Will Be revised.W/930730 Ltr | |
| ML20045J120 | 19 July 1993 | LER 93-011-00:on 930619,ESF Actuation Letdown Isolation Occurred While Synchronizing Main Unit Generator.Caused by Cooldown of RCS Due to Steam Demand.Plant Stabilized within Three Minutes & Pressurizer Level restored.W/930719 Ltr | |
| ML20045G459 | 8 July 1993 | LER 93-010-00:on 930614,determined That TS Surveillance on SI Accumulator Samples Missed Due to Draining & Refilling Accumulators Several Times During Outage.Accumulators a & C Immediately sampled.W/930708 Ltr | Boric Acid |
| ML20045F471 | 2 July 1993 | LER 93-009-00:on 930607,high Radiation Area Barrier Was Unlocked Due to Personnel Error.Comprehensive Confirmation Survey Performed,Personnel Interviewed & Task Force Formed. W/930702 Ltr | Time of Discovery High Radiation Area Locked High Radiation Area |
| ML20044F154 | 21 May 1993 | LER 93-007-00:on 930423,discoverd That Original Piping Did Not Conform to Design Code Requirement.Caused by Design Deficiency.Headers Fitted W/Code Approved End Caps & Tested & Now Conform to Design requirements.W/930521 Ltr | |
| ML20044F152 | 21 May 1993 | LER 93-008-00:on 930423,leakage Detected Through Two Check Valves in Chlorine Injection Line.Caused by Failure to Include Valves in ASME Section XI Testing Program.Check Valves Added to ASME Testing program.W/930521 Ltr | Hydrostatic |
| ML20044D525 | 14 May 1993 | LER 93-006-00:on 930415,two Operators Entered Posted Area W/O Radiation Monitoring Device & Entered Locked High Radiation Area & Left Barrier Open.Caused by Personnel Error in Judgement.Operators counseled.W/930514 Ltr | High Radiation Area Locked High Radiation Area |
| ML20024H119 | 15 May 1991 | LER 91-012-00:on 910415,excessive Max Operating Pressure Differential for Selected Solenoid Operated Valves Noted. Caused by Design Deficiencies.Equipment Mod Initiated to Replace Solenoid valve.W/910515 Ltr | |
| ML20029B254 | 4 March 1991 | LER 91-005-00:on 910131,steam Leakage in Auxiliary Feedwater Pumproom Caused ESF Actuation.Caused by Personnel Error. Control Room Operator Closed Steam Supply Isolation Valve to Stop Steam Leaking & Event Will Be reviewed.W/910304 Ltr | |
| ML17286B265 | 14 February 1991 | LER 90-006-01:on 900605,containment Isolation Valves Exceeded Stroke Time Limit,Per Tech Spec 3.6.3.1.Caused by Deficient Surveillance Program.Surveillance Procedures Revised to Include Stroke Time requirements.W/910214 Ltr | Stroke time |
| ML20028H739 | 23 January 1991 | LER 90-007-01:on 900622,containment Entry Performed to Determine If Flanges Installed,Per Info Notice 90-019. Flanges Immediately Removed.Caused by Procedural Deficiency. Transfer Canal Draining Procedures revised.W/910123 Ltr | |
| ML20024F744 | 14 December 1990 | LER 90-021-00:on 901113,ESF Actuation & Feedwater Isolation Occurred During MSIV Stroke Testing.Caused by Operator Error.Feedwater Isolation Signal Reset & Isolation Valves reopened.W/901214 Ltr | |
| ML20024F743 | 14 December 1990 | LER 90-023-00:on 901114,ESF Actuation & Feedwater Isolation Occurred in Response to Opening Condenser Steam Dump Valve. Caused by Operation of Steam Dump Sys in Steam Pressure Control Mode.Signal reset.W/901214 Ltr | |
| ML17285B473 | 18 July 1990 | LER 90-007-00:on 900622,refueling Cavity Drain Flanges Found to Be Installed During Operation.Caused by Deficiency in Transfer Canal Draining Procedure.Procedure Revised to Verify Removal of Flanges After Canal drained.W/900717 Ltr | |
| ML20043G577 | 15 June 1990 | LER 89-017-02:on 891218,atmospheric Steam Relief Valve C Opened to Lower MSIV C.Caused by Swell Phenomena Experienced After Opening MSIV C.Feedwater Isolation Signal Reset. W/900615 Ltr | |
| ML20043B517 | 23 May 1990 | LER 90-004-00:on 900423,inadvertent ESF Actuation Occurred During Safeguards Protection Sys Testing.Caused by Personnel Closing Breaker Before Resetting Safety Injection Sys Signal.Signal reset.W/900523 Ltr | |
| ML20043B520 | 23 May 1990 | LER 90-005-00:on 900423,inadvertent ESF Actuation Occurred During Quench Spray Flow Switch Calibr.Caused by Error in Procedure Resulting in Installation of Two Leads on Same Terminal.Discharge Valves opened.W/900523 Ltr | |
| ML20043A499 | 16 May 1990 | LER 88-005-01: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.W/900516 Ltr | |
| ML20012E668 | 29 March 1990 | LER 90-006-00:on 900227,plant Operation in Excess of Licensing Basis.Caused by Failure of Computer to Synchronize File Addresses in Task 3D.Heat Balance Calculations Reverified Using Data from Plant Variable Computer | Power change |
| ML20012C414 | 14 March 1990 | LER 90-002-00:on 900117,steam Generator B Channel 3 Pressure Transmitter Failed Low & Declared Inoperable.On 900119, Discovered That Channel Returned to Svc W/O Completing Required Time Response Testing on transmitter.W/900314 Ltr | |
| ML20012C727 | 14 March 1990 | LER 90-002-00:on 900217,steam Generator B Channel 3 Pressure Transmitter Failed Low & Declared Inoperable.Caused by Failure to Complete Tech Spec Required post-maint Test. Post-maint Test Procedure revised.W/900314 Ltr | |
| ML20012C063 | 8 March 1990 | LER 90-005-01:on 900209,defect Found in Casing of Limitorque Model HBC-1 Gear Operators,Causing Valve Motion to Cease Prematurely in Open Direction.Caused by Excess Matl on Housings.Also Reported Per Part 21.W/900308 Ltr | |
| ML20012C065 | 8 March 1990 | LER 90-003-01:on 900110,determined That Recirculation Spray HX River Water Radiation Monitor Sample Line Lacked Automatic,Remote Manual or Locked Shut Containment Isolation Valve.Request for Exemption Submitted to NRC.W/900308 Ltr | |
| ML20011F276 | 23 February 1990 | LER 90-004-00:on 900124:discovered That Control Rod Positions Not Recorded on Operator Logs on 890425 When Control Rod Insertion Limit Monitor & Deviation Alarm Out of Svc.Cause Not Stated.Personnel counseled.W/900223 Ltr | |
| ML20006F204 | 20 February 1990 | LER 90-002-00:on 900114,120-volt Ac Inverter for Vital Bus 3 Experienced Blown Dc Input Fuse When Inverter Bypassed & Aligned to 480-volt Ac Emergency Power.Caused by Mgt Action. Administrative Guidance issued.W/900220 Ltr | |
| ML20011E634 | 14 February 1990 | LER 90-005-00:on 900209,six Limitorque Corp Gear Operators, Model HBC-1,found to Contain Defect in Casting of Limit Stop Housing.Housings Machined to Remove Excess Matl.Item Reportable Per Part 21.W/900214 Ltr | |
| ML17223A746 | 9 February 1990 | LER 90-003-00:on 900110,determined That Recirculation Spray HX River Water Radiation Monitor Sample Lines Lacked Automatic,Remote Manual or Locked Shut Isolation Valve. Exemption Request from GDC 57 initiated.W/900209 Ltr | Exemption Request |
| ML20011E250 | 6 February 1990 | LER 90-001-00:on 900107,high Radiation Alarm Received on Steam Generator Blowdown (SGBD) Sample Radiation Monitor, Causing SGBD Sys Isolation.Caused by Crud Particles Swept Into Monitor.Monitor Purged & Returned to svc.W/890206 Ltr | |
| ML20006B403 | 26 January 1990 | LER 89-018-01:on 891227,reactor Trip Occurred Following Initial Startup from Refueling Outage.Caused by Trip of 480 Volt Ac Feeder Breaker to Rod Drive Motor Generator Sets. Installed Spare Breaker tested.W/900126 Ltr | |
| ML20006A871 | 23 January 1990 | LER 89-019-00:on 891227,discovered That Manual Reactor Trip Operating Surveillance Test Not Performed within Required Frequency Prior to Previous Reactor start-up on 891224. Caused by Inadequate start-up procedures.W/900123 Ltr | Missed surveillance |
| ML20006A890 | 23 January 1990 | LER 89-014-01:on 891101,routine Radiation Barrier Check Identified Faulty Door Locking Mechanism.Caused by Weld Latching Mechanism Plate Interfering W/Locking Action of Door.Mechanism Modified & Latch removed.W/900123 Ltr | High Radiation Area |
| ML20006A872 | 23 January 1990 | LER 89-009-01:on 890413,temporary Protection Covers Found on Five Temp Elements During Test of High Energy Line Break Temp Elements.Caused by Deficiency in Surveillance Program. Covers Immediately Removed from Temp elements.W/900123 Ltr | |
| ML20006A869 | 23 January 1990 | LER 89-017-01:on 891218,feedwater Isolation ESF Actuation, Caused by Swell Phenomena Experienced After Opening of C Msiv.Feedwater Isolation Signal Reset & Restored to Prefeedwater Isolation conditions.W/900118 Ltr | |
| ML19354E155 | 17 January 1990 | LER 89-017-00:on 891218,feedwater Isolation Occurred Due to Erroneous Level Transmitter Root Valve Position Indication. Operations Personnel Reset Feedwater Isolation Signal. W/900117 Ltr | |
| ML19354E107 | 16 January 1990 | LER 89-016-00:on 891215 & 16,erratic Level Transmitter Behavior Caused Steam Generator B hi-hi Level Feedwater Isolation.Caused by Inner Plugs Remaining Partially Inserted After Valves Opened.Plugs Freed from seats.W/900116 Ltr | |
| ML20005F890 | 12 January 1990 | LER 89-015-01:on 891213,operator Incorrectly Restored Solid State Protection Sys Generating Low Steamline Pressure Safety Injection Signal.Caused by Operator Error.Plant Restored to pre-safety Injection condition.W/900112 Ltr | |
| ML19332F505 | 12 December 1989 | LER 89-013-00:on 891112,4 Kv Bus 1A Power Supply Breaker Tripped on Phase overcurrent,de-energizing Emergency Bus 1A. Caused by Incorrect Tap Setting on Overcurrrent Relay.Relay Taps Reset & Breaker replaced.W/891211 Ltr | |
| ML20005D663 | 6 December 1989 | LER 89-027-00:on 891106,Train a Svc Water Pump Seal Water Supply Automatically Transferred to Backup Supply Due to Low Pressure.Caused by Seal Water Normal Supply Inadvertently Isolating While de-energizing.Manual revised.W/891206 Ltr | |
| ML19332E493 | 1 December 1989 | LER 89-014-00:on 891108,routine Radiation Barrier Check Identified Faulty Door Locking Mechanism on North Door to East Valve Trench Area.Caused by Welded Latching Mechanism. Locking Mechanism modified.W/891201 Ltr | High Radiation Area |
| ML19332D232 | 20 November 1989 | LER 89-026-00:on 891020,automatic Start of Auxiliary Feedwater Pumps Caused Steam Generator Blowdown Isolation. Caused by Inadequate Communications & Radiation Monitor Setpoint.Setpoint adjusted.W/891120 Ltr | |
| ML19325F182 | 8 November 1989 | LER 89-012-00:on 891010,in-core Instrumentation Guide Thimble Tubes Identified W/Degradation in Excess of 60% Wall Thickness.Caused by Mechanical Wear of Thimbles Against Reactor Vessel Internals.Tubes isolated.W/891108 Ltr | Finite Element Analysis |
| ML19327B870 | 31 October 1989 | LER 89-014-01:on 890506,supply Breaker to 480 Volt Essential Bus J Opened & Alternate Bus J Supply Breaker Did Not Close. Caused by Spurious Trip Due to Broken Circuit.Reset Button Returned to Normal Position & Breaker closed.W/891031 Ltr | |
| ML19324C374 | 30 October 1989 | LER 88-002-01:on 880127,radiation Monitors for Control Room Deenergized,Resulting in Actuation of Control Room Emergency Bottled Air Pressurization Sys.Cause Not Determined.Pressure Transmitter to Be replaced.W/891030 Ltr | |
| ML19327B185 | 20 October 1989 | LER 89-011-00:on 890920,engineering Determined That Rupture Restraint Gaps Were Opened to Greater than Original Design Analysis.Caused by Alignment Performed During Hot Functional Testing.Design Change Mod to Be performed.W/891020 Ltr | |
| ML19325C632 | 10 October 1989 | LER 89-025-00:on 890910,high Temps on Steam Generators B & C Auxiliary Feedwater Lines Identified.Caused by Improper Seating of Auxiliary Feedwater Check Valves.Procedure Initiated to Verify & Correct condition.W/891010 Ltr | Unanalyzed Condition |
| ML19325C885 | 9 September 1989 | LER 89-010-00:on 890907,UL Test Results Indicated That Horizontally Mounted Prototype Fire Dampers Failed to Comply W/Requirements of Ul Std 555-1968.Caused by Discrepancies Between as-fabricated & Required specs.W/891009 Ltr | Safe Shutdown Unanalyzed Condition Fire Barrier |
| ML18041A189 | 21 April 1989 | LER 89-005-00:on 890322,safety Injection Occurred Due to Low Pressurizer Pressure.Caused by Deficiencies in Safety Accumulator Check Valve Surveillance Test.Refueling Outage Calibr Procedures pre-reviewed by operators.W/890421 Ltr | |
| ML18041A188 | 14 March 1989 | LER 89-003-00:on 890212,noticed Erratic Operation of Main Feedwater Regulating Valve C & Turbine Trip/Reactor Trip Occurred Due to High Water Level in Steam Generator C.Caused by Valve Vibration & Hydraulic forces.W/890314 Ltr |