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 Issue dateTitleTopic
ML20024J2456 October 1994LER 94-006-00:on 940907,observed Receipt of Annunciator 12 Charging Pump Overload Trip.Caused by Overheated C Phase Loadside Connection at Mccb.Breaker Was Replaced & Tested. W/941006 Ltr
ML20029E47012 May 1994LER 94-001-00:on 940412,discovered That Total Pressure Offset Constant in Error.Caused by Technician Error. Procedure Will Be Revised to Prevent recurrence.W/940512 Ltr
ML20029D7764 May 1994LER 94-002-00:on 940303,noble Gas Monitor in R-35 Did Not Respond When source-checked During Surveillance.Caused by Component Failure.Corrective Actions:Monitor Repaired & Returned to svc.W/940504 LtrGrab sample
ML20046C7795 August 1993LER 93-009-00:on 930715,receipt of Annunciator Charging Pump 12 Overload Trip Observed by CR Operators,Resulting in Unplanned Closure of Containment Isolation Valve.Standby Charging Pump Started Immediately
ML20046A91526 July 1993LER 93-007-01:on 930413,discovered That Valves Required to Mitigate Consequences of Accident Not Included in Section XI ISI & Testing Program.On 930624,identified Six Addl Valve Inappropriately Ommitted from Subj Program.Valves IncludedSafe Shutdown
ML20046A89323 July 1993LER 93-008-00:on 930624,observed That Valve CV-31740, Instrument Air to Unit 1 Containment Closed Due to Failure of Coil in Solenoid Operated Pilot Valve.Valve Reopened Locally to Restore Instrument air.W/930723 Ltr
ML20044D21813 May 1993LER 93-002-00:on 930403,containment Isolation Valve Which Controls Reactor Makeup Water to Containment Exceeded Max Time for Closure.On 930413,lockwire & Safety Tag Removed. Caused by Communication Errors.Safety Tag Process Reviewed
ML20044D22413 May 1993LER 93-007-00:on 930413,discovered That Certain Feedwater Valves,Required to Mitigate Consequences of Accident,Not Included in ASME Section XI ISI & Test Program.Caused by Failure to Interpret Requirements.Valves TestedSafe Shutdown
ML20024H20623 May 1991LER 91-003-00:on 910423,auto-start Occurred of One Train of Auxiliary Bldg Special Ventilation Sys.Cause Unknown.Plant Mod Initiated Removing Unnecessary Wiring That Could Short Monitor module.W/910523 Ltr
ML20024G70022 April 1991LER 91-002-00:on 910323,auto-start of Control Room Special Ventilation Sys Occurred.Caused by Spike on Newly Installed Radiation Monitor.Wiring Changed to Provide Time Delay Feature for Remaining Four modules.W/910422 Ltr
ML20028H84928 January 1991LER 90-012-00:on 901229,control Room Operators Received Annunciation of Reactor Trip.Caused by Rod Control Sys Failures.Failed Cards in Rod Control Sys replaced.W/910128 Ltr
ML20028H04626 September 1990LER 89-018-03:on 891024,automatic Start of Auxiliary Bldg Ventilation Sys Occurred.Caused by Electronic Spike on Radiation Monitor.Radiation Monitor Modules Will Be Replaced by Upgraded Monitor module.W/900927 Ltr
ML20043G19715 June 1990LER 90-006-00:on 900517,electrical Spike on Radiation Monitor R-25 Caused auto-start of Spent Fuel Pool Special Ventilation Sys.Caused by Procedural Inadequacy.Request for Training Issued Re Basics of Procedure writing.W/900615 Ltr
ML20043E0604 June 1990LER 90-005-00:on 900504,control Room Received High Radiation Alarm & Indication of Automatic Start of Spent Fuel Pool Special Exhaust Fan 121 on Two Occasions.Caused by Electrical Spike on Monitor.Modules replaced.W/900604 Ltr
ML20043B60424 May 1990LER 90-004-00:on 900424,discovered That Surveillance Test SP1042, Resistance Temp Detector Bypass Flow Meter Functional Test Not Performed within Required Time Period. Caused by Personnel Error.Test performed.W/900524 LtrMissed surveillance
Grace period
ML20043E37618 May 1990LER 90-007-00:on 900517,discovered That Several Relays Deenergized & Automatic Start & Loading of Diesel Generator D1 Initiated.Caused by Inadequate Design.Mod Initiated to Install Test points.W/900608 Ltr
ML20042F5684 May 1990LER 89-021-01:on 891212,chlorine Monitors on One Train of Control Room Ventilation Inoperable for More than 11 H. Caused by Personnel Error.Operating Procedure for Chlorine Monitoring Sys Issued & Training provided.W/900504 Ltr
ML20042E68123 April 1990LER 90-003-00:on 900323,automatic Start of Safeguards Cooling Water Pump Occurred Due to Inadequate Procedures. Plant Procedures Revised to Improve Guidance for Detecting Loss of prime.W/900423 Ltr
ML20012D49419 March 1990LER 89-004-01:on 891221,reactor Trips & Loss of Power to Reactor Coolant Pumps Occurred.Caused by Malfunctions in MG Sets,Rod Control Sys & Substation Breaker Control Sys. Voltage Regulator for MG Set replaced.W/900319 Ltr
ML20006E82120 February 1990LER 90-002-00:on 900117,review of Cooldown Data Showed That Cooldown Rate of Pressurizer Exceeded Tech Spec Limit.Caused by Procedure Inadequacy.Procedures Revised to Require Use of Water Space Temp to Find Cooldown rate.W/900220 Ltr
ML20006E45816 February 1990LER 90-001-00:on 900117,technician Mirror Contacted Bare Power Supply Terminal & Shorted Terminal to Ground,Causing Power Supply to Trip & Isolation of Outside Air to Control Room.Exposed Wire Terminal Points covered.W/900216 Ltr
ML20006A97222 January 1990LER 89-004-00:on 891221,unit Tripped & Reactor Coolant Pumps Lost Power.Caused by Faulty Voltage Regulation of One CRD Mechanism motor-generator Set.Regulator for Set Replaced & Tested.On 891226,identical Trip occurred.W/900122 Ltr
ML20005G37311 January 1990LER 89-021-00:on 891211,computer Alarmed Indicating Malfunction of Chlorine Monitors 121 & 122 & Leaving Control Room Ventilation Sys Inoperable for More than 11 H.Caused by Personnel Error.Monitor 122 Returned to normal.W/900111 Ltr
ML19351A46811 December 1989LER 89-020-00:on 891108,17,20,23,1201 & 08,automatic Isolation of Control Room Supply & Exhaust Occurred.Caused by Malfunctions of Chlorine Gas Detectors.Addl Monitors Installed & Actuation Logic modified.W/891211 Ltr
ML20005D70730 November 1989LER 89-018-01:on 891024,25,31 & 1112,control Room Received High Radiation Alarm Which Initiated Automatic Start of Auxiliary Bldg Special Ventilation Sys.Caused by Radiation Monitor Spikes.Monitor Modules replaced.W/891130 Ltr
ML19332C61722 November 1989LER 89-018-00:on 891024,25 & 1112,control Room Received Train a High Radiation Alarm,Initiating Automatic Start of Auxiliary Bldg Special Ventilation Sys.Caused by Spike of Radiation Monitor.Monitor replaced.W/891122 Ltr
ML19332C62422 November 1989LER 89-003-00:on 891023,measured Leakage Rate Exceeded Tech Specs Limit While Performing Surveillance Test Sp 2136. Caused by Wear of Grafoil Packing Due to High Frequency of Door Usage.Test Procedures modified.W/891122 Ltr
ML19332C70020 November 1989LER 89-019-00:on 891025,Train a of Auxiliary Bldg Special Ventilation Sys Started Automatically When Power Mistakenly Turned Off.Caused by Personnel Error.Involved Personnel Counseled.Clarifying Revs Made to procedure.W/891121 Ltr
ML19325D49016 October 1989LER 89-017-00:on 890914,discovered That Present Position of Transfer Switch for Power Supplying Control & Protection Relays for Diesel Generator Does Not Meet Requirements of App R.Caused by Inadequate procedures.W/891016 LtrSafe Shutdown
ML19325C74910 October 1989LER 89-016-00:on 890908,control Room Received Train B High Radiation Alarm,Which Initiated Automatic Start of Auxiliary Bldg Special Ventilation Sys.Caused by Spike on Radiation Monitor 2R-30.Monitor Upgrade Being pursued.W/891010 Ltr
ML19325C1995 October 1989LER 89-015-00:on 890905 & 23,special Ventilation Sys of Control Rooms 122 & 121 Actuated Automatically.Caused by False High Chlorine Signal & Broken Chlorine Sensitive Paper Tape,Respectively.Detectors repaired.W/891005 Ltr
ML19325C1985 October 1989LER 89-014-00:on 890905,operations Personnel Recalled That SP1093.1 Performed Two Wks Previously Instead of SP1093.2. Caused by Personnel Error in Selecting Incorrect Procedure. Proper Notifications Made & SP1093.2 performed.W/891005 LtrMissed surveillance
ML20028E33012 January 1983LER 82-029/01T-0:on 821228,tiny through-wall Crack Found in heat-affected Zone of Weld on Safety Injection Supply Line from Boric Acid Storage Tanks.Cause Unknown. Fracture Mechanics Analysis UnderwayBoric Acid
ML20028C24430 December 1982LER 82-025/03L-0:on 821130,one Steam Flow Channel Differed from Redundant Channels During Power Reduction Due to out- of-calibr Transmitter.Cause Not Known.Transmitter Recalibr & Returned to Svc.Transmitter to Be Replaced If Drift Recurs
ML20028C36830 December 1982Signed LER 82-025/03L-0:on 821130,during Power Reduction,One Steam Flow Channel Differed from Redundant Channels. Transmitter Showed Out of Calibr.Cause Unknown.Transmitter Recalibr.Bistables Placed in Trip During Recalibr
ML20028C16522 December 1982LER 82-024/03L-0:on 821123,diesel Generator D1 Inoperable for Approx 4 Minutes After Lockout of Engine Shutdown Circuit Occurred.Probably Caused by Sticky Action of Speed Switch.Further Exam of Circuitry Will Be Performed
ML20028A97617 November 1982LER 82-021/03L-0:on 821027,following Use in Routine Sampling Procedure SV-33655,hot Leg Loop B Sample Inside Containment Isolation Valve Failed to Remain Closed.Caused by Malfunction of Limit Switch.Switch Replaced
ML20051A9567 May 1982LER 82-006/01T-0:on 820423,during Surveillance Test Sp 1104, Measured Reactor Coolant Boron Concentration Higher than Originally Predicted Value.Caused by Miscalculation of Predicted Worth.Analysis Performed to Monitor DisagreementBoric Acid
Shutdown Margin
ML20052B27321 April 1982LER 82-005/03L-0:on 820322,review of Chemistry Logs Showed That Boric Acid Tank 11 Had Not Been Sampled.Caused by Communication Breakdown.Tank Sampled & Involved Personnel Will Review ReptBoric Acid
ML20050A83324 March 1982LER 82-004/03L-0:on 820226,maint Workman Accidentally Bumped Overspeed Trip Mechanism on Auxiliary Feedwater Pump, Tripping Valve & Making Pump Inoperable.Caused by Personnel Error.Valve Operator Reset
ML20042A51012 March 1982LER 82-003/03L-0:on 820209,during Annual Visual Insp,One Steam Exclusion Control Damper Found Inoperable.Caused by Failure of Drive Gear in Pacific Air Products Damper Model R-35-FS.Gear Replaced
ML20049H60624 February 1982LER 82-001/03L-0:on 820125,one Overpower Delta T Summing Unit Found Out of Spec.Caused by Foxboro Model 66RC-OL Summing Unit Instrument Drift.Device Recalibr.Evaluation Underway
ML20049H68424 February 1982LER 82-002/03L-0:on 820125,one Overpower Delta T Summing Unit Found Out of Spec High.Caused by Instrument Drift. Device Recalibr
ML20041B40412 February 1982Updated LER 81-030/03L-0:on 811211,during Testing,Degraded Voltage Relay 27A1/B25 Found W/Voltage Setpoint Outside Allowable Band.Exact Cause Unknown.Relays Recalibr & Found to Operate Correctly
ML20041B39912 February 1982Updated LER 81-029/03L-0:on 811210,during Surveillance Test of Bus 16 Undervoltage Relays,Error in Disconnecting Test Equipment Resulted in Blown Fuse for A-phase Relays.Fuses Replaced & Normal Power Restored to Bus
ML20040A58415 January 1982LER 81-029/03L-0:on 811210,during Testing of Bus 16 Undervoltage Relays,Error in Disconnecting Test Equipment Resulted in Blown Fuse for a Phase Relays.Fuses Replaced. Undervoltage Relay Tests Will Be Revised
ML20040A56715 January 1982LER 81-030/03L-0:on 811210,degraded Voltage Relay 27A1/B25 Found W/Voltage Setpoint Outside Allowable Band.Causes Being Considered Are Last Calibr Error & Unfamiliarity W/Time Delay Relay Characteristics
ML20039E55230 December 1981LER 81-031/01T-0:on 811216,during Transfer of Spent Fuel in Preparation for Reracking of Pool 2,spent Fuel Assembly Top Nozzle Separated,Causing Assembly to Tip Toward Edge of Pool.Cause Unknown.Fuel Handling Operations Suspended
ML20039C27518 December 1981LER 81-028/03L-0:on 811118 & 1218,bistables 2-PC-431 G & I Found Out of Tolerance.Caused by Defective Potentiometer on 811118.On 811218,leads Were Tightened,Correcting Problem
ML20039C26816 December 1981LER 81-027/03L-0:on 811116,discovered That Pre,Absolute & Charcoal Filter Test Not Done on 11 Shield Bldg Ventilation Sys Replacement on 811112.Caused by Procedural Inadequacies & Poor Communications