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Category:LICENSEE EVENT REPORT (SEE ALSO AO
MONTHYEARML17313B0751999-08-27027 August 1999 LER 99-002-00:on 990730,test Mode Trip Bypass for EDG Output Breakers Not Surveilled.Cause Under Investigation.Operations Personnel Conservatively Invoked SR 3.0.3 for SR 3.8.1.13. with 990827 Ltr ML17313B0191999-07-16016 July 1999 LER 99-005-00:on 990618,RT on Low DNBR Was Noted.Caused by Hardware Induced Calculation Error.Cr Operator Was Taken to Place Reactor in Stable Condition IAW Appropriate Operating Procedure ML17313A9281999-05-0707 May 1999 LER 99-004-00:on 990408,PSV Lift Pressures Were Outside of TS Limits.Caused by Lift Pressure Setpoint Drift.Psvs Have Been Tested,Disassembled,Inspected,Reassembled & Certified at Wyle Labs ML17313A8951999-04-14014 April 1999 LER 99-003-00:on 990317,required Surveillance Requirement Not Completed Due to Deficient Procedure,Was Determined. Caused by Cognitive Personnel Error.St Procedures Revised to Require Chiller to Be Operating & Oil Temperature Checked ML17313A8921999-04-13013 April 1999 LER 98-003-01:on 980902,discovered That MSSV as-found Lift Pressures Were Outside TS Limits.Caused by Bonding of Valve Disc to Nozzle Seat.Affected Valves Were Adjusted,Retested & Returned to Svc ML17313A8891999-04-0909 April 1999 LER 99-001-00:on 990310,RT on High Pressurizer Pressure Was Noted.Caused by Loss of Heat Removal.Cr Supervisor Was Removed from Shift Duties for Diagnostics Skills Training. with 990409 Ltr ML17313A8361999-03-0101 March 1999 LER 99-001-00:on 990103,TS Violation for Power Dependent Insertion Limit Alarm Being Inoperable.Caused by Personnel Error.Revised Procedure to Clarify How Computer Point Is to Be Returned to Scan Mode.With 990302 Ltr ML17313A7701999-01-15015 January 1999 LER 96-008-00:on 960507,inadequate Procedure Results in Nuclear Power Channels Not Calibrated During Power Ascension Tests Occurred.Caused by Deficient Procedure.Procedure Revised ML17313A6611998-10-24024 October 1998 LER 98-008-00:on 980729,EQ of Electrical Connectors Were Not Adequately Demonstrated.Caused Because Test Was Conducted with Only Single Lv Connector & Without Fully Ranged Inputs. Revised EQ Requirements ML17313A5961998-09-14014 September 1998 LER 98-002-00:on 980814,B Train H Recombiner Was Noted Inoperable Due to cross-wired Power Receptacle.Cause of Event Is Under investigation.Cross-wired Power Supply Receptacle for B Train H Recombiner Was re-wired ML17313A5761998-09-0808 September 1998 LER 98-003-01:on 980113,discovered That One Channel of RWT Level Sys Had Failed High.Caused by Water Intrusion Into Electrical Termination Pull Box.Weep Holes Were Drilled Into Bottoms of Pull Boxes Nearest Level Transmitters ML17313A5591998-08-28028 August 1998 LER 98-001-00:on 980730,entered TS 3.0.3 Due to Safety Injection Flow Instruments Being Removed from Svc.Caused by Personnel Error.Transmitters Were Unisolated & Returned to svc.W/980828 Ltr ML17313A5201998-07-30030 July 1998 LER 98-004-00:on 980630,personnel Discovered That Pressure Safety Valve Had Not Received Periodic Set Pressure Test for ASME Class 1 Pressure Safety Valve.Caused by Personnel Error.Pressure Safety Valve reviewed.W/980730 Ltr ML17313A4671998-06-19019 June 1998 LER 98-007-00:on 980520,CR Personnel Observed Flow & Pressure Perturbations on Chemical & Vol Control Sys Letdown Sys.Caused by Cyclic Fatigue Due to Dynamic Pressure Transients.Unit Letdown Piping Replaced ML17313A4131998-06-0505 June 1998 LER 98-006-00:on 980507,determined That Plant Was Outside Design Basis Due to SI Discharge Check Valve Reverse Flow. Check Valve Was Disassembled,Examined & Reassembled, Whereupon Valve Met Acceptance Criteria ML17313A3951998-05-26026 May 1998 LER 98-005-00:on 980428,noted That Required Response Time Testing Had Not Been Performed.Caused by Personnel Error. Coached I&C Personnel Responsible for Reviewing Work Authorization Documentation ML17313A3251998-04-0101 April 1998 LER 98-004-00:on 980304,safety Valves as-found Pressures Out of Tolerance.Cause of Event Is Under Investigation.Three Mssv'S & Psv Will Be Replaced W/Refurbished & Recertified Valves During Refueling Outage U1R7 ML17313A3131998-03-21021 March 1998 LER 98-001-00:on 980301,surveillance Test Deficiency Found During Qaa Leads to TS 3.0.3/4.0.3 Entry.Caused by Personnel Error.Personnel Responsible for Inadequately Performed SR Were Coached ML17313A2251998-03-0505 March 1998 LER 93-005-00:on 930309,CR Personnel Discovered Missed TS LCO Action & Subsequently Performed Surveillance Satisfactorily.Caused by Personnel Error.Appropriate Disciplinary Action issued.W/980305 Ltr ML17313A2241998-02-26026 February 1998 LER 98-001-00:on 980130,reactor Protection & ESFAS Instrumentation Not Bypassed within one-hour Allowed by TS Occurred.Caused by Inadequate Procedures.Expectation to Detect Alarm Conditions Was Emphasized to CR Personnel ML17313A2081998-02-10010 February 1998 LER 97-007-00:on 971006,TS Violation Occurred Due to Inadequate Shutdown Cooling Flow During Modes 5 & 6 Operation.Independent Investigation of Event Was Conducted IAW APS CA program.W/980210 Ltr ML17313A2041998-02-0505 February 1998 LER 97-006-00:on 971028,missed TS 4.0.5 SR Was Noted.Caused by Personnel Error.Independent Investigation of Event Is Being Conducted IAW W/Aps Corrective Action Program ML17313A1201997-11-12012 November 1997 LER 97-006-00:on 971020,manual Reactor Trip Occurred Due to Vibration & Bearing Temp Increases in Reactor Coolant Pump. Caused by Failed Lower Journal Bearing.Bearing Assembly Was Disassembled,Inspected & Rebuilt ML17312B7181997-10-0707 October 1997 LER 97-003-00:on 970907,inadvertent Loss of Power & EDG Start Occurred Due to Procedural Error.Changed Train a & Train B Edg/Ist ST Procedures to Consistently Reflect Proper Pretest Staging Hand switches.W/971007 Ltr ML17312B7051997-09-26026 September 1997 LER 97-003-01:on 970215,seven Main Steam Safety Valves Were Found Out of Tolerance Prior to Refueling Outage.Safety Analysis Performed Based Upon as-found MSSV Data Which Demonstrated That MSSVs Would Perform Safety Functions ML17312B5531997-07-0707 July 1997 LER 97-002-00:on 970528,SR for Core Protection Was Not Performed Due to Inadequate Procedures.Revised Procedures ML17312B5501997-07-0707 July 1997 LER 97-003-00:on 970211,notified of Trevitest Activities Indicating That Total of Seven MSSVs Had as-found Lift Set Pressures Greater than 3 Percent Allowed by TS 3.7.1.1. Investigation Conducted.Seven MSSVs replaced.W/970707 Ltr ML17312B4971997-06-13013 June 1997 LER 97-002-00:on 970531,RT Occurred.Caused by Spurious Opening of All Four Rt Switchgear Breakers.Independent Investigation of Event Being Conducted in Accordance W/Util Corrective Action Program ML17312B1461996-12-17017 December 1996 LER 96-007-00:on 961119,surveillance Test Deficiencies Were Found During GL 96-01 Review Leading to TS 3.0.3 Entries. Caused by Increase in Scope of Required Testing.Supplement Will Be submitted.W/961217 Ltr ML17312A9511996-09-0404 September 1996 LER 96-003-00:on 960809,open Auxiliary Bldg Door Caused Full Bldg Essential Filtration Inoperability.Caused by Personnel Error.C/As Under consideration.W/960904 Ltr ML17312A8641996-07-17017 July 1996 LER 96-001-00:on 960621,inaccurate Gas Calculations for Post Accident Sampling Sys Occurred.Caused by Surveillance Test Worksheet Errors.Independent Investigation of Event Being conducted.W/960717 Ltr ML17300B2541996-06-11011 June 1996 LER 96-001-01:on 960404,inappropriate Grounding of Equipment Resulted in Condition Outside Design Basis of Plant. Established Fire Watches Required for Affected Areas ML17312A8081996-06-0909 June 1996 LER 96-002-00:on 960514,Tech Spec Violation Occurred Due to Erroneous Surveillance Requirement.Caused by Incorporation of C-E Generic Ts.Investigation Being conducted.W/960609 Ltr ML17312A7751996-05-17017 May 1996 LER 96-003-00:on 960122,missed Surveillance for Logic Check of Logs 1 & 2 Safety Excore Bypasses.Caused by Procedural Error.Log Power Functional Test Revised to Check Logs 1 & 2 Bypasses Regardless of Power level.W/960517 Ltr ML17312A7511996-05-0606 May 1996 LER 96-001-00:on 960404,smoke Discovered in Back Boards Area of CR by Security Officer,Performing Hourly Fire Watch Tour. Caused by Improperly Grounded Circuit.Investigation for Inappropriate Grounding of Low Voltage Power Sys Initiated ML17312A7241996-04-25025 April 1996 LER 96-002-00:on 960401,inappropriate Work Practice Resulted in Esfa of Train B Edg.Night Order Was Issued to All Three Units Describing event.W/960425 Ltr ML17312A6861996-04-0606 April 1996 LER 95-007-01:on 950512,determined That Bench Settings of air-operated Letdown & Containment Isolation Valves Adversely Affected Ability of Valves to Perform 10CFR50 App R Safety Function.Affected Valves Modified ML17312A5631996-02-22022 February 1996 LER 95-016-00:on 951212,containment Spray TS Violation Occurred Due to Unrecognized Valve Failure.Shim/Band Was Placed Around Stator of 1JSIBUV665 Motor Operator to Maintain Stator in Correct position.W/960222 Ltr ML17311B3381996-01-0909 January 1996 LER 95-014-00:on 951209,reactor Tripped Following Degradation of Main FW Flow.Caused by Malfunction of Fwcs Power supply,NNN-D11,transfer switch.NNN-D11 Aligned to Normal Power supply.W/960109 Ltr ML17311B3331995-12-31031 December 1995 LER 95-013-00:on 951201,AFW Sys Was Outside Design Basis of Plant.Caused by Design Error.Performed Assessment to Demonstrate That Existing Condition Does Not Pose Addl Safety concerns.W/951231 Ltr ML17311B2801995-11-23023 November 1995 LER 95-011-00:on 951018,identified Procedural Deficiency W/Msiv & FWIV ISTs Due to Personnel Error.Verified Operability of MSIVs & FWIVs.W/951123 Ltr ML17311B2531995-10-20020 October 1995 LER 95-002-00:on 950924,identified That Abnormal Blowdown Valves to Blowdown Flash Tank (Bft) Isolated,Resulting in Reactor Core Power Exceeding 3,800 Mwt Due to Personnel Error.Procedure for Aligning Blowdown to Bft Revised ML17311B1991995-09-21021 September 1995 LER 95-010-00:on 950727,equipment Qualification of Air Handling Unit Caused Essential Cw Pump to Be Inoperable. Used Work Orders to Drill Weep Holes in Motor Lead Connection boxes.W/950921 Ltr ML17311B1741995-09-0404 September 1995 LER 95-004-01:on 950329,containment Electrical Penetration Overcurrent Protective Devices Found Outside Design Basis. Caused by Error on Part of Original Architect Engineer. Modified Affected Circuits Critical to Normal Operational ML17311B1561995-08-27027 August 1995 LER 95-003-00:on 950729,switchyard Voltage Dropped Below Administratively Imposed Limit of 524 Kv for Approx 10 Seconds Due to Transient Grid Voltage.No C/A Taken Since Transmission Sys Transient Short duration.W/950827 Ltr ML17311B1551995-08-25025 August 1995 LER 95-002-01:on 950303,identified That Slb Analyses Failed to Consider as Initial Condition One Percent SDM for All Rods in (ARI) Due to Lack of Coordination & Unclear Div of Responsibilities.Ari Core Data Book SDM Curves Modified ML17311B1211995-08-16016 August 1995 LER 95-005-00:on 950717,RT on Low SG Water Level Was Result Following Degradation of MFW Flow.Completed Evaluation of Event ML17311B0841995-07-28028 July 1995 LER 94-005-01:on 941019,completed TS Required Shutdown Due to Expiration of LCO Time Limit.Design Change Options Identified & Will Be Reviewed to Determine If Valve &/Or Motor Operator Replacement or Mod Necessary ML17311B0721995-07-20020 July 1995 LER 95-004-00:on 950706,identified Four Occassions Between 950407 & 0630 When Conditional Surveillance in TS LCO 3.8.4.1 Action a Not Performed Due to Inattention to Detail. CR Copy of Temporary Procedure 40TP-9ZZ04 Corrected ML17311B0081995-07-0606 July 1995 LER 95-003-00:on 950613,TS LCO 3.0.3 Entered Following Loss of Both Trains of Essential Cw Sys & Both Hydrogen Recombiners.Caused by Spurious Actuations Due to Broken EDG Speed Probe Connector.Connector replaced.W/950706 Ltr 1999-08-27
[Table view] Category:RO)
MONTHYEARML17313B0751999-08-27027 August 1999 LER 99-002-00:on 990730,test Mode Trip Bypass for EDG Output Breakers Not Surveilled.Cause Under Investigation.Operations Personnel Conservatively Invoked SR 3.0.3 for SR 3.8.1.13. with 990827 Ltr ML17313B0191999-07-16016 July 1999 LER 99-005-00:on 990618,RT on Low DNBR Was Noted.Caused by Hardware Induced Calculation Error.Cr Operator Was Taken to Place Reactor in Stable Condition IAW Appropriate Operating Procedure ML17313A9281999-05-0707 May 1999 LER 99-004-00:on 990408,PSV Lift Pressures Were Outside of TS Limits.Caused by Lift Pressure Setpoint Drift.Psvs Have Been Tested,Disassembled,Inspected,Reassembled & Certified at Wyle Labs ML17313A8951999-04-14014 April 1999 LER 99-003-00:on 990317,required Surveillance Requirement Not Completed Due to Deficient Procedure,Was Determined. Caused by Cognitive Personnel Error.St Procedures Revised to Require Chiller to Be Operating & Oil Temperature Checked ML17313A8921999-04-13013 April 1999 LER 98-003-01:on 980902,discovered That MSSV as-found Lift Pressures Were Outside TS Limits.Caused by Bonding of Valve Disc to Nozzle Seat.Affected Valves Were Adjusted,Retested & Returned to Svc ML17313A8891999-04-0909 April 1999 LER 99-001-00:on 990310,RT on High Pressurizer Pressure Was Noted.Caused by Loss of Heat Removal.Cr Supervisor Was Removed from Shift Duties for Diagnostics Skills Training. with 990409 Ltr ML17313A8361999-03-0101 March 1999 LER 99-001-00:on 990103,TS Violation for Power Dependent Insertion Limit Alarm Being Inoperable.Caused by Personnel Error.Revised Procedure to Clarify How Computer Point Is to Be Returned to Scan Mode.With 990302 Ltr ML17313A7701999-01-15015 January 1999 LER 96-008-00:on 960507,inadequate Procedure Results in Nuclear Power Channels Not Calibrated During Power Ascension Tests Occurred.Caused by Deficient Procedure.Procedure Revised ML17313A6611998-10-24024 October 1998 LER 98-008-00:on 980729,EQ of Electrical Connectors Were Not Adequately Demonstrated.Caused Because Test Was Conducted with Only Single Lv Connector & Without Fully Ranged Inputs. Revised EQ Requirements ML17313A5961998-09-14014 September 1998 LER 98-002-00:on 980814,B Train H Recombiner Was Noted Inoperable Due to cross-wired Power Receptacle.Cause of Event Is Under investigation.Cross-wired Power Supply Receptacle for B Train H Recombiner Was re-wired ML17313A5761998-09-0808 September 1998 LER 98-003-01:on 980113,discovered That One Channel of RWT Level Sys Had Failed High.Caused by Water Intrusion Into Electrical Termination Pull Box.Weep Holes Were Drilled Into Bottoms of Pull Boxes Nearest Level Transmitters ML17313A5591998-08-28028 August 1998 LER 98-001-00:on 980730,entered TS 3.0.3 Due to Safety Injection Flow Instruments Being Removed from Svc.Caused by Personnel Error.Transmitters Were Unisolated & Returned to svc.W/980828 Ltr ML17313A5201998-07-30030 July 1998 LER 98-004-00:on 980630,personnel Discovered That Pressure Safety Valve Had Not Received Periodic Set Pressure Test for ASME Class 1 Pressure Safety Valve.Caused by Personnel Error.Pressure Safety Valve reviewed.W/980730 Ltr ML17313A4671998-06-19019 June 1998 LER 98-007-00:on 980520,CR Personnel Observed Flow & Pressure Perturbations on Chemical & Vol Control Sys Letdown Sys.Caused by Cyclic Fatigue Due to Dynamic Pressure Transients.Unit Letdown Piping Replaced ML17313A4131998-06-0505 June 1998 LER 98-006-00:on 980507,determined That Plant Was Outside Design Basis Due to SI Discharge Check Valve Reverse Flow. Check Valve Was Disassembled,Examined & Reassembled, Whereupon Valve Met Acceptance Criteria ML17313A3951998-05-26026 May 1998 LER 98-005-00:on 980428,noted That Required Response Time Testing Had Not Been Performed.Caused by Personnel Error. Coached I&C Personnel Responsible for Reviewing Work Authorization Documentation ML17313A3251998-04-0101 April 1998 LER 98-004-00:on 980304,safety Valves as-found Pressures Out of Tolerance.Cause of Event Is Under Investigation.Three Mssv'S & Psv Will Be Replaced W/Refurbished & Recertified Valves During Refueling Outage U1R7 ML17313A3131998-03-21021 March 1998 LER 98-001-00:on 980301,surveillance Test Deficiency Found During Qaa Leads to TS 3.0.3/4.0.3 Entry.Caused by Personnel Error.Personnel Responsible for Inadequately Performed SR Were Coached ML17313A2251998-03-0505 March 1998 LER 93-005-00:on 930309,CR Personnel Discovered Missed TS LCO Action & Subsequently Performed Surveillance Satisfactorily.Caused by Personnel Error.Appropriate Disciplinary Action issued.W/980305 Ltr ML17313A2241998-02-26026 February 1998 LER 98-001-00:on 980130,reactor Protection & ESFAS Instrumentation Not Bypassed within one-hour Allowed by TS Occurred.Caused by Inadequate Procedures.Expectation to Detect Alarm Conditions Was Emphasized to CR Personnel ML17313A2081998-02-10010 February 1998 LER 97-007-00:on 971006,TS Violation Occurred Due to Inadequate Shutdown Cooling Flow During Modes 5 & 6 Operation.Independent Investigation of Event Was Conducted IAW APS CA program.W/980210 Ltr ML17313A2041998-02-0505 February 1998 LER 97-006-00:on 971028,missed TS 4.0.5 SR Was Noted.Caused by Personnel Error.Independent Investigation of Event Is Being Conducted IAW W/Aps Corrective Action Program ML17313A1201997-11-12012 November 1997 LER 97-006-00:on 971020,manual Reactor Trip Occurred Due to Vibration & Bearing Temp Increases in Reactor Coolant Pump. Caused by Failed Lower Journal Bearing.Bearing Assembly Was Disassembled,Inspected & Rebuilt ML17312B7181997-10-0707 October 1997 LER 97-003-00:on 970907,inadvertent Loss of Power & EDG Start Occurred Due to Procedural Error.Changed Train a & Train B Edg/Ist ST Procedures to Consistently Reflect Proper Pretest Staging Hand switches.W/971007 Ltr ML17312B7051997-09-26026 September 1997 LER 97-003-01:on 970215,seven Main Steam Safety Valves Were Found Out of Tolerance Prior to Refueling Outage.Safety Analysis Performed Based Upon as-found MSSV Data Which Demonstrated That MSSVs Would Perform Safety Functions ML17312B5531997-07-0707 July 1997 LER 97-002-00:on 970528,SR for Core Protection Was Not Performed Due to Inadequate Procedures.Revised Procedures ML17312B5501997-07-0707 July 1997 LER 97-003-00:on 970211,notified of Trevitest Activities Indicating That Total of Seven MSSVs Had as-found Lift Set Pressures Greater than 3 Percent Allowed by TS 3.7.1.1. Investigation Conducted.Seven MSSVs replaced.W/970707 Ltr ML17312B4971997-06-13013 June 1997 LER 97-002-00:on 970531,RT Occurred.Caused by Spurious Opening of All Four Rt Switchgear Breakers.Independent Investigation of Event Being Conducted in Accordance W/Util Corrective Action Program ML17312B1461996-12-17017 December 1996 LER 96-007-00:on 961119,surveillance Test Deficiencies Were Found During GL 96-01 Review Leading to TS 3.0.3 Entries. Caused by Increase in Scope of Required Testing.Supplement Will Be submitted.W/961217 Ltr ML17312A9511996-09-0404 September 1996 LER 96-003-00:on 960809,open Auxiliary Bldg Door Caused Full Bldg Essential Filtration Inoperability.Caused by Personnel Error.C/As Under consideration.W/960904 Ltr ML17312A8641996-07-17017 July 1996 LER 96-001-00:on 960621,inaccurate Gas Calculations for Post Accident Sampling Sys Occurred.Caused by Surveillance Test Worksheet Errors.Independent Investigation of Event Being conducted.W/960717 Ltr ML17300B2541996-06-11011 June 1996 LER 96-001-01:on 960404,inappropriate Grounding of Equipment Resulted in Condition Outside Design Basis of Plant. Established Fire Watches Required for Affected Areas ML17312A8081996-06-0909 June 1996 LER 96-002-00:on 960514,Tech Spec Violation Occurred Due to Erroneous Surveillance Requirement.Caused by Incorporation of C-E Generic Ts.Investigation Being conducted.W/960609 Ltr ML17312A7751996-05-17017 May 1996 LER 96-003-00:on 960122,missed Surveillance for Logic Check of Logs 1 & 2 Safety Excore Bypasses.Caused by Procedural Error.Log Power Functional Test Revised to Check Logs 1 & 2 Bypasses Regardless of Power level.W/960517 Ltr ML17312A7511996-05-0606 May 1996 LER 96-001-00:on 960404,smoke Discovered in Back Boards Area of CR by Security Officer,Performing Hourly Fire Watch Tour. Caused by Improperly Grounded Circuit.Investigation for Inappropriate Grounding of Low Voltage Power Sys Initiated ML17312A7241996-04-25025 April 1996 LER 96-002-00:on 960401,inappropriate Work Practice Resulted in Esfa of Train B Edg.Night Order Was Issued to All Three Units Describing event.W/960425 Ltr ML17312A6861996-04-0606 April 1996 LER 95-007-01:on 950512,determined That Bench Settings of air-operated Letdown & Containment Isolation Valves Adversely Affected Ability of Valves to Perform 10CFR50 App R Safety Function.Affected Valves Modified ML17312A5631996-02-22022 February 1996 LER 95-016-00:on 951212,containment Spray TS Violation Occurred Due to Unrecognized Valve Failure.Shim/Band Was Placed Around Stator of 1JSIBUV665 Motor Operator to Maintain Stator in Correct position.W/960222 Ltr ML17311B3381996-01-0909 January 1996 LER 95-014-00:on 951209,reactor Tripped Following Degradation of Main FW Flow.Caused by Malfunction of Fwcs Power supply,NNN-D11,transfer switch.NNN-D11 Aligned to Normal Power supply.W/960109 Ltr ML17311B3331995-12-31031 December 1995 LER 95-013-00:on 951201,AFW Sys Was Outside Design Basis of Plant.Caused by Design Error.Performed Assessment to Demonstrate That Existing Condition Does Not Pose Addl Safety concerns.W/951231 Ltr ML17311B2801995-11-23023 November 1995 LER 95-011-00:on 951018,identified Procedural Deficiency W/Msiv & FWIV ISTs Due to Personnel Error.Verified Operability of MSIVs & FWIVs.W/951123 Ltr ML17311B2531995-10-20020 October 1995 LER 95-002-00:on 950924,identified That Abnormal Blowdown Valves to Blowdown Flash Tank (Bft) Isolated,Resulting in Reactor Core Power Exceeding 3,800 Mwt Due to Personnel Error.Procedure for Aligning Blowdown to Bft Revised ML17311B1991995-09-21021 September 1995 LER 95-010-00:on 950727,equipment Qualification of Air Handling Unit Caused Essential Cw Pump to Be Inoperable. Used Work Orders to Drill Weep Holes in Motor Lead Connection boxes.W/950921 Ltr ML17311B1741995-09-0404 September 1995 LER 95-004-01:on 950329,containment Electrical Penetration Overcurrent Protective Devices Found Outside Design Basis. Caused by Error on Part of Original Architect Engineer. Modified Affected Circuits Critical to Normal Operational ML17311B1561995-08-27027 August 1995 LER 95-003-00:on 950729,switchyard Voltage Dropped Below Administratively Imposed Limit of 524 Kv for Approx 10 Seconds Due to Transient Grid Voltage.No C/A Taken Since Transmission Sys Transient Short duration.W/950827 Ltr ML17311B1551995-08-25025 August 1995 LER 95-002-01:on 950303,identified That Slb Analyses Failed to Consider as Initial Condition One Percent SDM for All Rods in (ARI) Due to Lack of Coordination & Unclear Div of Responsibilities.Ari Core Data Book SDM Curves Modified ML17311B1211995-08-16016 August 1995 LER 95-005-00:on 950717,RT on Low SG Water Level Was Result Following Degradation of MFW Flow.Completed Evaluation of Event ML17311B0841995-07-28028 July 1995 LER 94-005-01:on 941019,completed TS Required Shutdown Due to Expiration of LCO Time Limit.Design Change Options Identified & Will Be Reviewed to Determine If Valve &/Or Motor Operator Replacement or Mod Necessary ML17311B0721995-07-20020 July 1995 LER 95-004-00:on 950706,identified Four Occassions Between 950407 & 0630 When Conditional Surveillance in TS LCO 3.8.4.1 Action a Not Performed Due to Inattention to Detail. CR Copy of Temporary Procedure 40TP-9ZZ04 Corrected ML17311B0081995-07-0606 July 1995 LER 95-003-00:on 950613,TS LCO 3.0.3 Entered Following Loss of Both Trains of Essential Cw Sys & Both Hydrogen Recombiners.Caused by Spurious Actuations Due to Broken EDG Speed Probe Connector.Connector replaced.W/950706 Ltr 1999-08-27
[Table view] Category:TEXT-SAFETY REPORT
MONTHYEARML17300B3811999-09-30030 September 1999 Monthly Operating Repts for Sept 1999 for Pvngs,Units 1,2 & 3.With 991007 Ltr ML17300B3271999-08-31031 August 1999 Monthly Operating Rept for Aug 1999 for Pvngs,Units 1,2 & 3 ML17313B0751999-08-27027 August 1999 LER 99-002-00:on 990730,test Mode Trip Bypass for EDG Output Breakers Not Surveilled.Cause Under Investigation.Operations Personnel Conservatively Invoked SR 3.0.3 for SR 3.8.1.13. with 990827 Ltr ML17313B0611999-07-31031 July 1999 Monthly Operating Repts for July 1999 for Pvngs,Units 1,2 & 3.With 990810 Ltr ML17313B0191999-07-16016 July 1999 LER 99-005-00:on 990618,RT on Low DNBR Was Noted.Caused by Hardware Induced Calculation Error.Cr Operator Was Taken to Place Reactor in Stable Condition IAW Appropriate Operating Procedure ML17300B3151999-06-30030 June 1999 Monthly Operating Repts for June 1999 for Pvngs,Units 1,2 & 3.With 990714 Ltr ML17313A9921999-06-21021 June 1999 Special Rept:On 990525,RMS mini-computer Was Removed from Service to Implement Yr 2000 Mod & Was OOS Longer than 72 H Allowed.Caused by Planned Y2K Mods.Preplanned Alternate Sampling Program Was Initiated ML17313A9911999-06-18018 June 1999 Special Rept:On 990510,loose-part Detection Sys Channel 2 Was Declared Inoperable.Caused by Malfunction of Mineral Cable Connector to Accelerometer.Licensee Will Implement Modifications Which Will Enhance loose-part Detection Sys ML17313A9731999-05-31031 May 1999 Monthly Operating Repts for May 1999 for Pvngs,Units 1,2 & 3.With 990608 Ltr ML17313A9281999-05-0707 May 1999 LER 99-004-00:on 990408,PSV Lift Pressures Were Outside of TS Limits.Caused by Lift Pressure Setpoint Drift.Psvs Have Been Tested,Disassembled,Inspected,Reassembled & Certified at Wyle Labs ML17313A9201999-04-30030 April 1999 Monthly Operating Repts for Apr 1999 for Pvngs,Units 1,2 & 3.With 990512 Ltr ML17313A8951999-04-14014 April 1999 LER 99-003-00:on 990317,required Surveillance Requirement Not Completed Due to Deficient Procedure,Was Determined. Caused by Cognitive Personnel Error.St Procedures Revised to Require Chiller to Be Operating & Oil Temperature Checked ML17313A8921999-04-13013 April 1999 LER 98-003-01:on 980902,discovered That MSSV as-found Lift Pressures Were Outside TS Limits.Caused by Bonding of Valve Disc to Nozzle Seat.Affected Valves Were Adjusted,Retested & Returned to Svc ML17313A8891999-04-0909 April 1999 LER 99-001-00:on 990310,RT on High Pressurizer Pressure Was Noted.Caused by Loss of Heat Removal.Cr Supervisor Was Removed from Shift Duties for Diagnostics Skills Training. with 990409 Ltr ML17300B3071999-03-31031 March 1999 Seismic Portion of Submittal-Only Screening Review of Palo Verde Nuclear Generating Station Units Ipeee. ML17313A8801999-03-31031 March 1999 Monthly Operating Repts for Mar 1999 for Pvngs,Units 1,2 & 3.With 990412 Ltr ML20207M9231999-03-12012 March 1999 Amended Part 21 Rept Re Cooper-Bessemer Ksv EDG Power Piston Failure.Total of 198 or More Pistons Have Been Measured at Seven Different Sites.All Potentially Defective Pistons Have Been Removed from Svc Based on Encl Results ML20207H7471999-03-10010 March 1999 1999 Emergency Preparedness Exercise 99-E-AEV-03003 ML17313A8361999-03-0101 March 1999 LER 99-001-00:on 990103,TS Violation for Power Dependent Insertion Limit Alarm Being Inoperable.Caused by Personnel Error.Revised Procedure to Clarify How Computer Point Is to Be Returned to Scan Mode.With 990302 Ltr ML17313A8501999-02-28028 February 1999 Monthly Operating Repts for Feb 1999 for Palo Verde Nuclear Generating Station.With 990311 Ltr ML17313A7791999-02-0505 February 1999 Safety Evaluation Accepting Licensee Rev to Emergency Plan That Would Result in Two Less Radiation Protection Positions Immediatelu Available During Emergencies ML17313A8061999-01-31031 January 1999 Monthly Operating Repts for Jan 1999 for Pvngs,Units 1,2 & 3.With 990218 Ltr ML17313A7701999-01-15015 January 1999 LER 96-008-00:on 960507,inadequate Procedure Results in Nuclear Power Channels Not Calibrated During Power Ascension Tests Occurred.Caused by Deficient Procedure.Procedure Revised ML17313A7381998-12-31031 December 1998 Monthly Operating Repts for Dec 1998 for Palo Verde Nuclear Generating Station,Units 1,2 & 3.With 990113 Ltr ML20206H2101998-12-31031 December 1998 SCE 1998 Annual Rept ML17313A7031998-11-30030 November 1998 Monthly Operating Repts for Nov 1998 for Pvngs,Unit 1,2 & 3. with 981209 Ltr ML17313A6701998-11-0404 November 1998 Rev 2 to PVNGS Unit 2 Colr. ML17313A6741998-10-31031 October 1998 Monthly Operating Repts for Oct 1998 for Pvngs,Units 1,2 & 3.With 981109 Ltr ML17313A6611998-10-24024 October 1998 LER 98-008-00:on 980729,EQ of Electrical Connectors Were Not Adequately Demonstrated.Caused Because Test Was Conducted with Only Single Lv Connector & Without Fully Ranged Inputs. Revised EQ Requirements ML17313A6561998-09-30030 September 1998 Monthly Operating Rept for Sept 1998 for PVNGS Units 1,2 & 3.With 981007 Ltr ML17313A5961998-09-14014 September 1998 LER 98-002-00:on 980814,B Train H Recombiner Was Noted Inoperable Due to cross-wired Power Receptacle.Cause of Event Is Under investigation.Cross-wired Power Supply Receptacle for B Train H Recombiner Was re-wired ML17313A5761998-09-0808 September 1998 LER 98-003-01:on 980113,discovered That One Channel of RWT Level Sys Had Failed High.Caused by Water Intrusion Into Electrical Termination Pull Box.Weep Holes Were Drilled Into Bottoms of Pull Boxes Nearest Level Transmitters ML17313A5591998-08-28028 August 1998 LER 98-001-00:on 980730,entered TS 3.0.3 Due to Safety Injection Flow Instruments Being Removed from Svc.Caused by Personnel Error.Transmitters Were Unisolated & Returned to svc.W/980828 Ltr ML20151S0941998-08-21021 August 1998 Rev 6 to COLR for PVNGS Unit 3 ML20151S0861998-08-21021 August 1998 Rev 4 to COLR for PVNGS Unit 1 ML20151S0901998-08-21021 August 1998 Rev 1 to COLR for PVNGS Unit 2 ML18066A2771998-08-13013 August 1998 Part 21 Rept Re Deficiency in CE Current Screening Methodology for Determining Limiting Fuel Assembly for Detailed PWR thermal-hydraulic Sa.Evaluations Were Performed for Affected Plants to Determine Effect of Deficiency ML17313A5401998-08-13013 August 1998 Special Rept:On 980715,declared PASS Inoperable.Caused by Failure of Offgas Flush/Purge Control Handswitch HS0101. Handswitch Replaced & Post Maintenance Retesting Was Initiated ML17313A5301998-07-31031 July 1998 Monthly Operating Repts for July 1998 for Pvgns,Units 1,2 & 3.W/980812 Ltr ML17313A5201998-07-30030 July 1998 LER 98-004-00:on 980630,personnel Discovered That Pressure Safety Valve Had Not Received Periodic Set Pressure Test for ASME Class 1 Pressure Safety Valve.Caused by Personnel Error.Pressure Safety Valve reviewed.W/980730 Ltr ML17313A5791998-07-0707 July 1998 to PVNGS SG Tube ISI Results for Seventh Refueling Outage Mar & Apr 1998. ML17313A5001998-06-30030 June 1998 Monthly Operating Repts for June 1998 for Palo Verde Nuclear Generating Station,Units 1,2 & 3.W/980710 Ltr ML17313A4671998-06-19019 June 1998 LER 98-007-00:on 980520,CR Personnel Observed Flow & Pressure Perturbations on Chemical & Vol Control Sys Letdown Sys.Caused by Cyclic Fatigue Due to Dynamic Pressure Transients.Unit Letdown Piping Replaced ML17313A4521998-06-19019 June 1998 Rev 5 to COLR for Pvngs,Unit 3. ML17313A4501998-06-19019 June 1998 Rev 4 to COLR for Pvngs,Unit 3. ML17313A4131998-06-0505 June 1998 LER 98-006-00:on 980507,determined That Plant Was Outside Design Basis Due to SI Discharge Check Valve Reverse Flow. Check Valve Was Disassembled,Examined & Reassembled, Whereupon Valve Met Acceptance Criteria ML17313A4211998-05-31031 May 1998 Monthly Operating Repts for May 1998 for Pvngs,Units 1,2 & 3.W/980609 Ltr ML17313A3951998-05-26026 May 1998 LER 98-005-00:on 980428,noted That Required Response Time Testing Had Not Been Performed.Caused by Personnel Error. Coached I&C Personnel Responsible for Reviewing Work Authorization Documentation ML17313A3691998-04-30030 April 1998 Monthly Operating Repts for Apr 1998 for PVNGS.W/980412 Ltr ML17313A3251998-04-0101 April 1998 LER 98-004-00:on 980304,safety Valves as-found Pressures Out of Tolerance.Cause of Event Is Under Investigation.Three Mssv'S & Psv Will Be Replaced W/Refurbished & Recertified Valves During Refueling Outage U1R7 1999-09-30
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)I 1 J REGULATORY INFORMATION DISTRIBUTION SYSTEM (RZDS)ACCESSION NBR:9904200382 DOC.DATE: 99/04/09 NOTARIZED:
NO DOCKET FACIL:STN-50-528 Palo Verde Nuclear Station, Unit 1, Arizona Publi 05000528 AUTH.NAME-AUTHOR AFFILIATION MARKS,D.G.
Arizona Public Service Co.(formerly Arizona Nuclear Power OVERBECK,G.R.
Arizona Public Service Co.(formerly Arizona Nuclear Power RECZP.NAME RECIPIENT AFFILIATION
SUBJECT:
LER 99-001-00:on 990310,RT on high pressurizer, pressure was noted.Caused by loss of heat removal.CR supervisor was removed from shif t duties for diagnostics skills training.With 990409 ltr.DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR ENCL SIZE: TITLE: 50.73/50.9 Licensee Event Report (LER), ncident Rpt, etc.NOTES: STANDARDIZED PLANT 05000528 C RECIPIENT ID CODE/NAME LPD4-2 PD INTERNAL: ACRS LE CE ER NRR DIPM IQMB NRR/DSSA/SPLB RGN4 FILE'01 COPIES LTTR ENCL 1 1 1 1 1 1 1 1 1 1 1 1 RECIPIENT ID CODE/NAME FIELDS,M AEOD/SPD/RRAB NRR/DIPM/IOLB NRR/DRIP/REXB RES/DET/EIB COPIES LTTR ENCL 1 1 1 1 1 1 1 1'1 1 EXTERNAL: L ST LOBBY WARD NOAC POORE,W.NRC PDR 1 1 1 1 1 1 LMITCO MARSHALL NOAC QUEENER,DS NUDOCS FULL TXT 1 1 1 1 1 1 NOTE TO ALL"RIDS" RECIPIENTS:
PLEASE HELP US TO REDUCE WASTE.TO HAVE YOUR NAME OR ORGANIZATION REMOVED FROM DISTRIBUTION'LIST OR REDUCE THE NUMBER OF COPIES RECEIVED BY YOU'OR YOUR ORGANIZATION, CONTACT THE DOCUMENT CONTRO DESK (DCD)ON EXTENSION 415-2083 FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES'EQUIRED:
LTTR 17 ENCL 3/7
.ig)l Commitmnnr.
Innnrnlinn.
&every.Paio Verde Nuciear Generating Station Gregg R.Overbeck Vice President Nuclear Production TEL 602/393-5148 FAX 602I3934077 Mail Station 7602 P.O.Box 52034 Phoenix, AZ 85072-2034 192-01042-GRO/DGM/RjH April 9, 1999 U.S.Nuclear Regulatory Commission ATi N: Document Control Desk Mail Station P1-37 Washington, D.C.20555-0001
Dear Sirs:
Subject:
Palo Verde Nuclear Generating Station (PVNGS)Unit 1 Docket No.STN 50-528 License No.NPFP1 Licensee Event Report 99-001-00 Attached please find Licensee Event Report (LER)99-001-00 prepared and submitted pursuant to 10 CFR 50.73.This LER reports an automatic reactor trip on high pressurizer pressure due to a loss of heat removal.In addition to the reactor trip, the unit received an engineered safety feature actuation of the main steam system (MSIS)on high steam, generator water level.There are.no commitments generated as a result of this LER.In accordance with 10CFR50.73(d), a copy of this LER is being forwarded to the Regional Administrator, NRC Region IV.If you have any questions, please contact Daniel G.Marks, Section Leader, Regulatory Affairs, at (623)393-6492.-
Sincerely, GRO/DGM/RJH/rlh Attachment cc: E.W.Merschoff P.H.Harrell M.B.Fields J.H.Moorman INPO Records Center 9904200382 990409~PDR ADOCK 05000528 S PDR (all with attachment)
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NRC FORM 366 (5-1998}U.S.N CLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER)(See reverse for required number of digits/characters for each block)APPRO BY OMB NO.3160%104 EXPIRES 06/30/2001 Estimated burden per response to comply with this mandatory information collection request: 50 hrs.Reported lessons learned are incorporated into the licensing process and fed back to industry.Forward comments regarding burden esumate to the Records Management Branch (TW F33), U.S.Nudear Regulatory Commission.
Washington, DC 20555-0001
~and to the PapenNork Reduction Project (3150-0104}, office of Management and BydgeL Washington.
DC 20503.If an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information cosection FACILITY NAME{1}Palo Verde Nuclear Generating Station Unit1 DOCKETNUMBER{2}
05000528 PAGE{3}1 OF 7 Reactor Trip On High Pressurizer Pressure Due To A Loss Of Heat Removal EVENT DATE (5)LER NUMBER (6)REPORT DATE (7)OTHER FACILITIES INVOLVED (8)MONTH DAY YEAR 03 10 1999 SEQUENTIAL REVISION YEAR NUMBER NUMBER 1999-001 00 MONTH DAY YEAR 04 09 1999 FACILITY NAME N/A FACILITY NAME N/A DOCKET NUMBER 05000 DOCKET NUMBER 05000 OPERATING MODE (9)THIS REPORT IS SUBMITTED 20.2201 b PURSUANT TO THE REQUIR 20.2203 a 2 v EMENTS OF 10 CFR: Check o 50.73 a 2 i ne or more 11 50.73 a 2 vru POWER LEVEL (10)100 20.2203 a 1 20.2203 a 2 i 20.2203 a 2 ii 20.2203 a 2 iii 20.2203 a 2 iv 20.2203 a 3 I 20.2203 a 3 ii 20.2203 a 4 50.36 c 1 50.36 c 2 LICENSEE CONTACT FOR THIS LER (12)50.73 a 2 u 50.73 a 2 iii 50.73 a 2 iv 50.73 a 2 v 50.73 a 2 vii 50.73 a 2 x 73.71 OTHER Specify in Abstract below or ln NRC Form 3BBA NAME anie.Mar s, ection ea er, egu atory A airs TELEPHONE NUMBER (InoNde Area Code)623-393-6492 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT 13 CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLE To EPIX CAUSE SYSTEM REPORTAB COMPONENT MANUFACTURER LE TO'PIX X SJ COMP F180 BV SB IICNTRL G080 SUPPLEMENTAL REPORT EXPECTED 14 YES (If yes, complete EXPECTED SUBMISSION DATE).X NO EXPECTED SUBMISSION DATE (15)MONTH DAY YEAR ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)(16)On March 10, 1999 at approximately 1325 MST, Palo Verde Unit 1 was in Mode 1 (POWER OPERATION), operating at approximately 100%power, when a reactor trip occurred due to a loss of heat removal capability caused by improper operator intervention following a spurious closure of the main turbine control*valves.An electrical malfunction caused the main turbine control valves to close decreasing the electrical load on the turbine.The steam bypass control system (SBCS)responded to maintain the loss of heat removal caused by the load shed.The control room supervisor directed the secondary operator to place the SBCS to emergency off which initiated a reduction in heat removal and resulted in a reactor coolant pressure increase to the high pressurizer pressure setpoint, subsequently tripping the reactor.In addition to the reactor trip, the unit received an engineered safety feature actuation system actuation of the main steam system (MSIS)on high steam generator-2 level due to the steam generator-2 economizer valve not staying fully closed and allowing level to reach the MSIS setpoint.At approximately 1335 MST, the unit was stabilized in Mode 3 (HOT STANDBY)and the shift manager classified the event as an uncomplicated reactor trip.All safety systems functioned as required.There were no other safety system actuations and none were required.The preliminary cause of the turbine control valves going closed was a failure of the throttle pressure sensing circuit.An equipment root cause of failure is in progress.The cause of the reactor trip was attributed to supervisory methods that did not ensure sufficient information was collected to support an operational decision.No previous similar events have been re orted ursuant to 10CFR50.73.
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NRC FORM 366A (6-1998)U.S.NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER)TEXT CONTINUATION FACILITY NAME (1)Palo Verde Nuclear Generating Station Unit 0 TEXT (lf more spaceis required, use additional copies of NRC Form 366A)(17)DOCKET NUMBER(2)05000528 LER NUMBER (6)SEQUENTIAL REVISION NUMBER NUMBER 1999-001-000 PAGE (3)2 OF 7 1.REPORTING REQUIREMENT:
This LER 530/99-001-00 is being submitted to report an event that resulted in the automatic actuation of an engineered safety feature (ESF)(JE), including the reactor protection system (RPS)(JC)as specified in 10CFR50.73(a)(2)(iv).
Specifically, on March 10, 1999, at approximately 1326 MST, Palo Verde Unit 1 was in Mode 1 (POWER OPERATION), operating at approximately 100%power, when a reactor trip occurred following a spurious closure of the main turbine control valves (CV).An electrical malfunction caused the main turbine control valves to close decreasing the electrical load on the turbine.The steam bypass control system (SBCS)responded to the loss of heat removal caused by the load shed.Operations personnel (utility-licensed operator)noted that all eight steam bypass control valves opened and concurrently verifiedno rod bottom lights were lit on the core mimic.The control room supervisor directed.the secondary operator to place the SBCS in emergency off which initiated a reduction in heat removal and resulted in a reactor coolant pressure increase to the high pressurizer pressure setpoint, subsequently tripping the reactor.In addition to the reactor trip, the unit received an engineered safety feature actuation system (ESF)actuation of the main steam system (MSIS)on high level in steam generator-2 due to the steam generator-2 economizer valve not staying fully closed and allowing level to reach the MSIS setpoint.In accordance with 10CFR50.72 (b)(2)(ii), at approximately 1645 MST on March 10, 1999, a one hour non-emergency ENS call (ENS ID 35456)was made for a,RPS/ESF actuation.
2.EVENT DESCRIPTION:
Prior to the automatic trip, at approximately 1325 MST on March 10, 1999, control room personnel observed EHC and other alarms via the RJ computer screen.Subsequently, all eight steam bypass control system (SBCS)permissives activated and turbine bypass control valves quick opened.Control room personnel observed no trip annunciators on the main turbine, no rod bottom lights lit, no CEAs inserted on the CEAC CRT screen, and no reactor power cutback, concurrent with the SBCVs opening and suspected a possible overpower event was occurring and placed the SBCS in emergency off.As a result of the decrease in heat removal, reactor pressure increased to the high pressurizer pressure setpoint 2283 psia and at approximately 1326 MST, the reactor automatically tripped on high pressurizer pressure.All control element assemblies(CEA)(AA)inserted as designed.The reactor trip initiated a main turbine/main generator trip (TA/TB).Secondary system pressure was discharged briefly via atmospheric dump valves (ADVs)and main steam safety valves (MSSVs).The total discharge duration was approximately 12 minutes of which 4 minutes were on the safeties.
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NRC FORM 366A (6-1996)FACILITY NAMg (1)U.S.NUCLEAR REGULATORY'COMMISSION LICENSEE EVENT REPORT (LER)TEXT CONTINUATION DOCKET NUMBER(2)LER NUMBER (6)PAGE (3)Palo Verde Nuclear Generating Station Unit1 TEXT (If more space is required, use additional copies of NRC Form 366A)(17)05000528 SEQUENTIAL, REVISION NUMBER NUMBER 1999-001-000 3 OF 7 2.EVENT DESCRIPTION cont': The unit was stabilized at approximately 1335 MST in Mode 3 (Hot Standby)and the Shift Manager classified the event as an uncomplicated reactor trip.At.approximately 1429 MST a main steam isolation signal (MSIS)safety system actuation occurred due to high steam generator-2 levels The level in steam generator-2 increased to the MSIS setpoint of 91 percent narrow range.The level increase in steam generator-2 occurred approximately five minutes after the secondary operator placed both downcomer valves in the automatic position.The cause of the level increase was due to a faulty timer card for the economizer control valve..There were no other safety system actuations and none were required.Required safety systems responded to the event as designed.The timer card was tested and re-installed..
An equipment root cause of failure is underway to determine the problem.3.ASSESSMENT OF THE SAFETY CONSEQUENCES AND IMPLICATIONS OF THIS EVENT: A safety limit evaluation was performed as part of the APS investigation.
The evaluation determined that the plant responded as designed, that no safety limits were exceeded, and that the event was bounded by the current safety analysis.The reactor trip did not result in a transient more severe than those already analyzed in Chapter 15 of the Updated Final Safety Evaluation Report (UFSAR).Scenarios concerning a decrease in heat removal by the secondary system or loss of normal feedwater flow remain bounding for this event.All CEAs inserted as designed.This event did not challenge shutdown margin criteria.Both primary and secondary system pressures remained well below 110 percent of the design pressures.
Four main steam safety valves lifted for approximately 4 minutes during the event.Engineering review of the safety valve performance indicated that all four safety-valves performed as required.Post trip testing of safety valve performance is discussed in the additional information section 8.The specified acceptable fuel design limits (SAFDL)were not exceeded during this event.The pl'ant response was normal for the situation that occurred.The event did'ot result in any challenges to the fission product barriers or result in the release of radioactive materials in excess of quantities allowed by 10CFR20.Therefore, there were no adverse safety consequences or implications as a result of this event.This event di.d not adversely affect the safe operation of the plant or the health and safety of the public.
4i I NRC FORM 366A (6-1998)FACILITY NAME (1)U.S.NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER).TEXT CONTINUATION DOCKET NUMBER(2)LER NUMBER (6)PAGE (3)'alo Verde Nuclear Generating Station Unit 1 05000528 TEXT (If more space is required, use addi Iional copies of NRC Form 366A)(17)SEQUENTIAL REVISION NUMBER NUMBER 1999-001-000 4 OF 7 4.CAUSE OF THE EVENT: 'An independent investigation of this event is being conducted in accordance with the APS corrective action program.The investigation determined, that the reactor tripped due to high pressurizer pressure when secondary heat removal was reduced by operations placing the SBCS to emergency-off.
A preliminary evaluation has determined'he apparent root cause to be personnel error in that supervisory methods did not ensure that sufficient information was collected to support operations decision to place the SBCS in emergency-off.
The apparent cause of the turbine control valves closing was a failure of the throttle pressure sensing circuit.An equipment root cause evaluation is underway for'his issue.The apparent cause of the post trip MSIS was due to a faulty timer card that controls the steam generator economizer valves.During the event the negative ten percent signal to the economizer valve was lost.The loss of the signal was due to loss of power to the card through its back plate connector..
The card was removed and tested in the rework shop and performed satisfactory.
The card,was re-installed in the field panel and tested several times and functioned'roperly.
An equipment root cause evaluation is underway for this issue.P No unusual characteristics of the work location (e.g., noise, heat, poor lighting)directly contributed to the event.No procedural errors contributed to the event.5.STRUCTURES, SYSTEMS, OR COMPONENTS INFORMATION:
An independent investigation of this event is being conducted in accordance with the APS corrective action program.The investigation has determined that the reactor automatically tripped on high pressurizer pressure following the spurious closing of the main turbine control valves causing a large load reduction.
A prel'iminary root cause of failure analysis (ERCFA)determined that the apparent root cause of the main turbine control valves closing is attributed to an electronic failure in the throttle pressure sensing circuit which controls valve position and regulates steam flow to the main turbine.The failure of the sensing circuit caused all four main turbine control valves to close.The failed pressure sensing circuit is currently in the instrument and control rework facility to determine the specific failure mode.A.new pressure sensing circuit was installed and turbine control valves were returned to service.If the final ERCFA results differ from this determination, a supplement to this report will be submitted to describe the fina3.root cause determination., A transportability review was conducted for Units 2 and 3 to determine if a potential failure of the pressure sensing circuit exists.No abnormal failure modes or repetitive problems were discovered.
~I ig),t NRC FORM 366A (6-1 996)FACILITY NAME (1)U.S.NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER)TEXT CONTINUATION DOCKET NUMBER(2)LER NUMBER (6)PAGE (3)Palo Verde Nuclear Generating Station Unit1 TEXT (if more space is required, use additional copies of NRC Form 366A)(17)05000528 SEQUENTIAL REVISION NUMBER NUMBER 1999-001-000 5 OF 7 5.STRUCTURES, SYSTEMS, OR COMPONENTS INFORMATION cont': An evaluation was also conducted to determine the cause of the MSIS.A preliminary ERCFA determined.that the apparent root cause for the MSIS, post trip, was due to a problem with the timer card on the feedwater control system causing the steam generator-2 economizer valve to remain open approximately 1 percent, increasing the level in steam generator-2 to the high setpoint for MSIS.During the event the negative ten percent signai to the economizer valve was lost.The loss of the signal was due to loss of power to the card through its back plate connector.
The card was re-installed in the field panel and tested several times and fun'ctioned properly.This card is normally inactive during normal operations and is needed during feedwater crossover or during post trip conditions.
The risk of a timer card failure during normal operations is low.After extensive troubleshooting efforts, the problem with the card could not be repeated and was determined to be satisfactory for reinstallation.
The timer card was re-installed in the system for continued use.A root cause evaluation is underway to determine the failure mode.A transportability review will be conducted as part of the ERCFA.The timer card is manufactured by Foxboro and is a Spec 200 part number KY354F2.There are no indications that any structures, systems, or components were inoperable at the start of the event, which contributed, to the event.No other component or system failures were involved.No failures of components with multiple functions were involved.No failures that rendered a train of a safety system inoperable were involved.6.CORRECTIVE ACTIONS TO PREVENT RECURRENCE:
As immediate corrective action, the control room supervisor was removed from shift duties for diagnostics skills training.A human performance evaluation
.(HPES)is underway to determine personnel performance issues surrounding the event.Preliminary results from the HPES indicate that the primary cause was inadequate operator response in that the control room staff did not fully evaluate plant parameters prior to making the decision to place the SBCS in emergency-off.
The evaluation also concluded that operations procedures, command and control, communications, shift staffing and stress levels were all satisfactory,and did not contribute to the event.If the final HPES evaluation results differ from those previously stated, a supplement to this report will be submitted to describe the final HPES determination.
ig)IP NRC FORM 366A (6-1998)FACILITY NAME (1)U.S.NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER)TEXT CONTINUATION DOCKET NUMBER(2)LER NUMBER (6)PAGE (3)Palo Verde Nuclear Generating Station Unit 1 TEXT (if more space is required, use addi!ional copies of NRC Form 366A)(17)05000528 SEQUENTIAL REVISION NUMBER NUMBER 1999-001-000 6 OF 7 6.CORRECTIVE ACTIONS TO PREVENT RECURRENCE cont'd: An ongoing evaluation is being conducted in accordance wi;th the APS Corrective Action Program to address the root cause of failure for the main turbine control valve and steam generator economizer control valve failures.As immediate corrective action, the main turbine control valve throttle pressure sensing circuit was replaced.An ERCFA is underway to determine the failure mode and will be completed by July 30, 1999.'uring the event the negative ten percent signal to the economizer valve was lost.The loss of the signal was due to loss of power to the card through its back plate'connector.
The card was re-installed in the field panel and'ested several times and functioned properly.The timer card for the steam generator economizer control valve was tested satisfactorily, re-installed and returned to service.After extensive troubleshooting efforts, the problem with the card could not be repeated and was determined to be satisfactory for reinstallation.
The timer card was re-installed in the system for continued use.A root cause evaluation is underway to determine the failure mode and will be completed by July 30, 1999.A transportability review will be conducted as part of the ERCFA.To enhance operator awareness of the anomalies associated with this event, the lessons learned will be placed in the Licensed Operator Continued Training (LOCT).As part of LOCT, addi:tional training will be given on anomalies associated with isolation of the steam generator economizer valves by August 15, 1999.Operations management wi.'ll evaluate the need for additional diagnostic skills training for licensed operators following completion of the HPES evaluation by June 30, 1999.7.PREVIOUS SIMILAR EVENTS: Although previous similar events have been reported pursuant to 10CFR50~73 in the past three years for automati'c actuation o'f an ESF, including RPS, the causes discussed in the previous events have not been similar to this event.Therefore, the corrective actions taken to address previous similar events, would not have prevented this event.
Ol ig>I NRC FORM 366A (6-1996)U.S.NUCLEAR REGULATORY COMMISSION LICENSEE EVENT'REPORT (LER)TEXT CONTINUATION FACILITY NAME (1)~DOCKET NUMBER(2)LER NUMBER (6)PAGE (3)Palo Verde Nuclear Generating Station Unit 1 05000528 TEXT (If more space is required, use additional copies of NRC Form 366A)(17)SEQUENTIAL REVISION NUMBER NUMBER 1999-001-000 7 oF 7 8.ADDITIONAL INFORMATION Unit Restart Based on the contingency action plan and on reviews by the Plant Review Board, the Management Response Team, and the Incident Investigation Team, unit restart was authorized by the Operations Director in accordance with approved procedures.
At approximately 2228 on March 12, 1999,'nit 1 entered Mode l,and at approximately 0121 MST on March 13, 1999 Unit 1 was synchronized on the grid.MSSV Performance Subsequent to the reactor trip, secondary system pressure rose above 1250 psig resulting in the operation of four MSSVs.Based on available instrument readings, four MSSVs lifted within their expected lift pressure settings and limited secondary peak pressure to approximately 1282 psig during the event.One MSSV (SGE-PSV-561), with a design lift of 1250 psig, did not lift during the event.Engineering performed an evaluation of SGE-PSV-561 performance and determined that the actual steam line pressure that this valve experienced during the event may not have been sufficient to cause it to lift.Post trip testing was conducted for this MSSV to confirm the lift setting was within Technical Specification acceptance limits.The as found lift setting was determined to be approximately
3.8 percent
above the design lift pressure which is outside the Technical Specification limit.The MSSV was declared inoperable at approximately 1434 MST, on March 13, 1999 and the lift settings were adjusted and returned to service within the LCO completion time.Although SGE-PSV-561 post trip test results were outside of Technical Specification limits, there were no safety consequences's a result of this condition in that the MSSVs performed as expected during the event and prevented over-pressurization of the secondary system.
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