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 Issue dateTitleTopic
ML20024J2487 October 1994LER 94-012-00:on 940907,discovered Failure to Perform TS Surveillance Requirements.Caused by Misunderstanding & Inadequate Technical Reviews.Ts Bases for 3/4.8.1 Will Be revised.W/941007 LtrSafe Shutdown
Enforcement Discretion
Missed surveillance
ML20029E55813 May 1994LER 94-005-00:on 940415,dicovered That Several Valves Were Not Being Tested Per Requirements of ASME Section Xi.Caused by Inappropriate Action.Corrective Action:Pump & Valve Team Has Been Formed to Perform in Depth reviews.W/940513 LtrPower Operated Valves
ML20029D99411 May 1994LER 94-006-00:on 940415,determined That on 921103, Unidentified RCS Leak Rate of Greater than 1 Gpm Occurred. Caused by Error in RCS Mass Balance Equation.Approved Temporary Change to Procedure OP-903-024.W/940511 Ltr
ML20045H47315 July 1993LER 93-002-00:on 930615,reactor Tripped Due to High SG Level Caused by Failure of Feedwater Control Sys.Caused by Failure of Square Root Extractor in Feedwater Flow Circuit.Failed Components Replaced & Alarm Setpoints reviewed.W/930715 Ltr
ML20029B6388 March 1991LER 89-007-01:on 890331,inadequate Design of Air Accumulators Due to Inadequate Review of Design Requirements Implemented as Part of post-TMI Action Plan.Design Change 3195 Phase I implemented.W/910308 LtrUnanalyzed Condition
High Radiation Area
Safe Shutdown Earthquake
ML20029A84728 February 1991LER 90-019-01:on 901212,both Trains of Control Room Heating Ventilation & Air Conditioning Sys Inoperable Due to Breach in Control Room Envelope.Caused by Air Flow Past Retaining Angle.Leakage Paths repaired.W/910228 LtrFire Barrier
Fire impairment
ML20028G9632 October 1990LER 90-013-00:on 900903,unsampled Gas Released from Gaseous Waste Mgt Sys.Caused by Internal Leakage Past Discharge Isolation Valves.Administrative Controls in Place to Ensure That Gas Decay Tanks Sampled Prior to release.W/901002 Ltr
ML20028G92124 September 1990LER 90-012-00:on 900825,reactor Tripped Due to Lightning Strike.Station Mod Request Issued to Provide Uninterruptable Power Source for Steam Bypass Control sys.W/900924 Ltr
ML20044A66627 June 1990LER 90-006-00:on 841218.determined That Shutdown Cooling Sys Relief Valve Setpoint Not Set,Per Tech Spec Requirement. Caused by Procedural Inadequacy.Procedure MM-007-006 revised.W/900627 Ltr
ML20043G19615 June 1990LER 90-001-01:on 900223,discovered Controlled Ventilation Area Sys Airlock Doors D-170 & D-171 Open.Caused by Inadequate Administrative Controls.Procedural Instructions Developed to Govern Control of Air Lock doors.W/900615 LtrFire impairment
Fire Protection Program
ML20043G20414 June 1990LER 89-006-01:on 870105,safety Class Break Requirements Not Met.Caused by Programmatic Breakdown in Administrative Controls.Valves Closed & Design Drawings & Procedures revised.W/900614 LtrSafe Shutdown
Boric Acid
ML20043B11221 May 1990LER 90-005-00:on 900420,condenser Vacuum Pump Discharge Wide Range Gas Monitor Setpoint Discovered to Be Incorrect.Caused by Inadequate Change Procedure for Data Base Manual. Administrative Procedures revised.W/900521 Ltr
ML20042F7507 May 1990LER 90-004-00:on 900408,partial Actuation of Emergency Feedwater Sys Occurred During Scheduled Test of Plant Protection Sys.Caused by Test Circuit Malfunction.Relay Hold Pushbutton Assembly replaced.W/900507 Ltr
ML20012D66723 March 1990LER 90-001-00:on 900223,discovered Controlled Ventilation Area Sys Airlock Doors D-170 & D-171 Open.Caused by Inadequate Administrative Controls.Procedural Instructions Will Be developed.W/900323 LtrFire Barrier
Fire impairment
ML19354E01822 January 1990LER 89-024-00:on 891223,manual Trip of Plant Initiated in Response to Decreasing Level in Steam Generator.Caused Probably by Anomaly in Main Feed Regulating Valve Pneumatic Control Sys.Tent Erected Around valve.W/900122 Ltr
ML19354E01719 January 1990LER 89-023-00:on 890927,MSIV 2MS-124B,determined to Have Broken Stem.Caused by MSIV Hydraulic Control Unit Thermal Valve Leakage.Replacement MSIV Stems W/Increased Blend Radius Designed to Decrease Stress installed.W/900119 Ltr
ML20005E09729 December 1989LER 89-017-01:on 890819,automatic Reactor Trip Initiated by Plant Protection Sys Response to Variations in Core Axial Shape Index.Caused by Failure of Pulldown & Lower Gripper Coil Current Sensors.Equipment replaced.W/891229 LtrBoric Acid
Shutdown Margin
ML20011D25420 December 1989LER 89-022-00:on 891128,plant Operated in Condition Prohibited by Tech Specs When Emergency Diesel Generator a Inoperable More than 24 H.Caused by Personnel Error.Ltr Issued to All Shift supervisors.W/891220 Ltr
ML20011F45918 December 1989LER 89-021-00:on 891116,emergency Diesel Generator a Declared Inoperable When Essential Svcs Chiller a Declared Inoperable W/O Verifying Availability of Offsite Ac Power. Caused by Personnel Error.Supervisor counseled.W/891218 LtrMissed surveillance
ML19332C57820 November 1989LER 89-020-00:on 891031,containment Fan Cooler C Motor Ran in Reverse Direction Reducing Air Flow & Cooling Capacity. Caused by Personnel Not Performing Surveillance Testing. Motor Rewired for Correct Slow Speed operation.W/891120 Ltr
ML19327C11113 November 1989LER 89-002-01:on 890125,discovered That Safety Classification of Instrument Air Tubing That Supplies Outlet Isolation Valves Installed as non-nuclear Safety.Caused by Use of Weld Filler Matl.Tech Spec Change SentSafe Shutdown
Boric Acid
Safe Shutdown Earthquake
ML19324C46113 November 1989LER 89-019-00:on 891012,4.16-kV Bus 3A2 Metering Potential Transformer Fuse Door Inadvertently Opened,Causing Feeder Breaker & Supply Breaker to Open & Load Sequencer to Reset. Caused by Personnel Error.Drawers relabeled.W/891113 Ltr
ML19327B35123 October 1989LER 89-018-00:on 890921,while Testing Main Steam Safety Valve,Lift Pressure Found to Be Below Tech Spec Allowable Value.Caused by Error in Judgement by Plant Supervisors. Event Will Be Discussed by superintendent.W/891023 LtrEnforcement Discretion