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Category:LICENSEE EVENT REPORT (SEE ALSO AO
MONTHYEARML17292B7421999-07-20020 July 1999 LER 99-001-00:on 990628,ESF Signal Closed All Eight MSIVs While Plant Was Shutdown.Caused by Failure of Relay RPS-RLY-K10D.Subject Relay Was Replaced & Tested on 990630. with 990720 Ltr ML17292B4451998-10-27027 October 1998 LER 98-012-01:on 980715,failure to Comply with Requirements of TS SR 3.8.4.7 Was Noted.Caused by Inadequate Work Practices.Training Session Was Held with Personnel.With 981027 Ltr ML17284A7561998-09-0303 September 1998 LER 98-013-00:on 980805,ESF Actuations Were Noted Due to Deenergization of Vital Electrical Bus SM-8.Caused by Inadequate Direction in Troubleshooting Plan.Will Conduct Training for Engineering Personnel.With 980903 Ltr ML17284A7571998-09-0202 September 1998 LER 98-014-00:on 980807,completion of TS 3.8.1.F Required Shutdown Due to Inoperability of EDG-2 Was Noted.Caused by Degraded Voltage Regulator for DG-2.Replaced Voltage Regulator & Associated Scrs.With 980902 Ltr ML17284A7551998-09-0202 September 1998 LER 98-015-00:on 980808,discovered Reactor Coolant Pressure Boundary Leak During Shutdown Conditions.Caused by Leakage from Socket Weld (Fwb 63) on Elbow Connection.Failed Piping Connection Was Replaced.With 980902 Ltr ML17284A7311998-08-17017 August 1998 LER 98-012-00:on 980716,determined That 24-month SR 3.8.4.7 Had Not Been Fulfilled within Specified Frequency.Caused by Inadequate Work Practices.License Requested & Received Enforcement Discretion Re Battery Svc test.W/980817 Ltr ML17284A7121998-07-23023 July 1998 LER 98-006-01:on 980520,discovered Discrepancies in Low Voltage Bus Calculations During Review of 10CFR50,App R Calculations for High Impedance Faults.Caused by Inadequate Work Practices.Implemented Procedural Changes ML17284A6951998-07-17017 July 1998 LER 98-011-00:on 980617,ECCS Pump Room Flooding Was Noted Due to FP Sys Pipe Break.Caused by Inadequate Design of FP Sys.Detailed Review of FP Sys Design Was Conducted. W/980717 Ltr ML17284A6961998-07-15015 July 1998 LER 98-010-00:on 980615,TS Required Shutdown Due to Inoperability of TIP Sys Isolation Valve Was Noted.Caused by Improper Installation of TIP Tubing.Reattached Affected Tubing & Inspected Other TIP tubing.W/980715 Ltr ML17284A6731998-07-0101 July 1998 LER 98-009-00:on 980606,nuclear Steam Supply Shutoff Sys Group 3 & 4 Isolations During Testing Was Noted.Caused by Procedural Deficiency.Counseled Individuals Involved in preparation.W/980701 Ltr ML17284A6651998-06-24024 June 1998 LER 98-007-00:on 980530,inadvertent Full Scram & Division 1 ECCS Injection Was Noted.Caused by Failure to Meet Mgt Work Practice Expectation When Encountering Deficient Procedure. Incident Review Board Convened to Review event.W/980624 Ltr ML17284A6641998-06-24024 June 1998 LER 98-008-00:on 980531,inadvertent Full Scram During RPV Leak Testing in Mode 4 Was Noted.Caused by Change in Mgt Techniques.Revised Procedures to Take Into Account Addl Water Head in Pressure Sensing lines.W/980624 Ltr ML17284A6631998-06-19019 June 1998 LER 98-006-00:on 980520,discovered Discrepancies in Low Voltage Bus Calculations During Review of App R Calculations for High Impedance Fault Analysis.Caused Indeterminate. Implemented Procedural Changes Involving Operator Action ML17284A6551998-06-0404 June 1998 LER 98-005-00:on 980506,potential for Failure of RHR Sys Valve to Close on Isolation Signal Was Noted.Caused by Design Deficiency.Caution Tag Was Placed on RHR-V-40 Control Switch to Inform Plant Operators of limitation.W/980604 Ltr ML17284A6421998-06-0101 June 1998 LER 98-004-00:on 980502,determined That Primary Containment Penetration Overcurrent Protection Does Not Meet Reg Guide 1.63 Requirements.Caused by Inadequate Design Changes. Installed Addl Fuse in RHR-MO-9 circuit.W/980601 Ltr ML17292B3281998-04-0909 April 1998 LER 98-002-00:on 980311,reactor Scram & Plant Transient Occurred,Due to Failed Closed Main Steam Isolation Valve. Caused by Loss of Pneumatic Actuating Supply Pressure. Problem Evaluation Request Written for Failure of MS-V-22D ML17292B3291998-04-0909 April 1998 LER 98-003-00:on 980311,WNP-2 Experienced SCRAM Signal as Result of Low Rpv.Caused by Less than post-SCRAM Operational Strategy for Resetting SCRAM Signal in Conditions.Changes in post-SCRAM Operational Strategy implemented.W/980409 Ltr ML17292B2661998-03-0404 March 1998 LER 98-001-00:on 980203,automatic Start of HPCS EDG Was Noted.Caused by Operator Error.Operations Crew Stabilized Plant at Approximately 75% Reactor Power & Investigation of Event Was initiated.W/980304 Ltr ML17292B1111997-11-10010 November 1997 LER 97-011-00:on 971010,HPCS Battery Charger Failed.Caused by Failure of a Phase Firing Control Circuit Board Due to Aging During 7 Yrs of Use.Hpcs Sys Was Immediately Declared inoperable.W/971110 Ltr ML17292B1151997-11-0707 November 1997 LER 97-010-00:on 970906,discovered That TS SR 3.4.5.1 for Identified Portion of RCS Total Leakage Would Not Be Able to Perform within Time Limits of SR 3.0.2.Caused by Inadequate Methods.Method of Meeting SR 3.4.5.1 Established ML17292B0641997-09-24024 September 1997 LER 97-004-01:on 970327,plant Operators Manually Scrammed Reactor as Required by TS Due to Indication of Entry Into Region a of power-to-flow Map.Caused by Inadequate Attention to Detail.Established Event Evaluation teams.W/970924 Ltr ML17292B0241997-08-18018 August 1997 LER 97-009-00:on 970717,discovered Error in Recently Performed Inservice Testing procedure,OSP-TIP/IST-R701. Caused by Procedure Inadequacy.Plant Procedure OSP/TIP/IST-R701 Will Be changed.W/970818 Ltr ML17292B0291997-08-15015 August 1997 LER 97-008-00:on 970716,wire Seal Used to Lock Containment Instrument Air Pressure Control valve,CIA-PCV-2B,found Not Intact.Cause of Misadjustment of CIA-PCV-2B Unknown.Event Will Be Communicated to Plant employees.W/970815 Ltr ML17292B0201997-08-15015 August 1997 LER 97-S01-00:on 970718,failure to Take Compensatory Measure for Inoperative Microwave Security Zone Occurred. Caused by Personnel Error.Training Will Be Conducted W/ Appropriate Members of Security force.W/970815 Ltr ML17292A9481997-07-23023 July 1997 LER 97-007-00:on 970611,voluntary Rept of Automatic Start of DG-1 & DG-2 Was Experienced.Caused by Undervoltage Condition on Electrical Busses SM-7 & SM-8.Circulating Water Pump CW-P-1C Control Switch Placed in pull-to-lock.W/970723 Ltr ML17292A9201997-06-26026 June 1997 LER 97-006-00:on 970527,non-performance of Surveillance Requirement 3.6.1.3.2 for Blind Fanges,Was Noted.Caused Because Misunderstanding of Intent of Specs.Added Five Structural Assemblies for SP.W/970626 Ltr ML17292A8331997-04-28028 April 1997 LER 97-004-00:on 970327,plant Operators Manually Scrammed Reactor as Required by TS Due to Entry Into Region a of power-to-flow Map Following Planned Trip of Single Mfp. Event Evaluation teams,established.W/970428 Ltr ML17292A8311997-04-28028 April 1997 LER 97-005-00:on 970327,valid Reactor Scram Signal Received Due to Low Water Level Condition During Preparations for SRV Testing.Caused by Risks & Consequences of Decisions Not Completely Identified.Restored Water level.W/970428 Ltr ML17292A8251997-04-21021 April 1997 LER 97-003-00:on 970320,notification of Noncompliance W/Ts as TS SRs for Response Time Testing Were Not Being Met for Specified Instrumentation in Rps,Pcis & Eccs.Requested Enforcement Discretion for One Time exemption.W/970421 Ltr ML17292A7431997-03-20020 March 1997 LER 97-002-00:on 970218,determined That Rod Block Monitor (RBM) Calibr Values Were Not Set IAW Tech Specs.Caused by Calibr Procedures Inadequacies.Revised & re-performed RBM Channel Calibr procedures.W/970330 Ltr ML17292A7401997-03-13013 March 1997 LER 97-001-00:on 970211,reactor Water Cleanup Sys Blowdown Flow Isolation Setpoint Was Slightly Above TS Allowable Valve Occurred Due to Calculation Error.Lds Fss LD-FS-15 LD-FS-16 Were Declared inoperable.W/970313 Ltr ML17292A6641997-01-22022 January 1997 LER 96-009-00:on 961220,miscalculation of Instantaneous Overcurrent Relay Settings Resulted in Inoperability of safety-related Equipment.Caused by Utilization of Inappropriate Design.Testing Was completed.W/970122 Ltr ML17292A6461997-01-0606 January 1997 LER 96-008-00:on 961205,failure to Comply with TS Action Requirement for Emergency Core Cooling Sys Actuation Instrumentation Occurred Due to Unidentified Inoperability Condition.Pmr initiated.W/970106 Ltr ML17292A6371996-12-19019 December 1996 LER 96-007-00:on 961122,electrical Breakers Were Not Seismically Qualified in Test/Disconnect Position.Circuit Breaker Mfg Did Not Consider Raced Out Breaker Position During Testing.Relocated Circuit breakers.W/961217 Ltr ML17292A4121996-08-0808 August 1996 LER 96-006-00:on 960709,average Power Range Monitor Rod Block Downscale Surveillance Not Performed Prior to Entry Into Mode 1.Caused by long-standing Misinterpretation of Requirements of Tss.Procedures revised.W/960808 Ltr ML17292A3801996-07-24024 July 1996 LER 96-004-00:on 960624,plant Was Manually Scrammed by Control Room Personnel Due to Reactor Water Level Transient Experienced During Testing of Digital Feedwater Sys.Caused by Programming Error.Sys Was corrected.W/960724 Ltr ML17292A3771996-07-24024 July 1996 LER 96-005-00:on 960624,determined Missed Surveillance Test Re Channel Check of Average Power Range Monitor.Caused by Inadequate Procedures.Revised Surveillance Procedure Re When APRM Checks Must Be performed.W/960724 Ltr ML17292A3641996-07-12012 July 1996 LER 96-003-00:on 960615,required Surveillance Test Not Performed When Required by TS 3.4.1.3.Caused by Inadequate Procedures.Implementing Surveillance Procedure & Reactor Plant Startup Procedures revised.W/960712 Ltr ML17292A3361996-06-20020 June 1996 LER 96-002-00:on 960504,critical Bus SM-8 Lost Power When Supply Breaker 3-8 Tripped.Caused by Personnel Error. Operators Counselled & Procedures revised.W/960620 Ltr ML17292A2861996-05-24024 May 1996 LER 96-001-00:on 960425,inadvertent ESF Actuations Occurred Due to Tripping of Temporary Power Supply to IN-3.Caused by Personnel Error.Operations Restored to IN-3 Loads & Reset ESF actuations.W/960524 Ltr ML17291B0891995-10-19019 October 1995 LER 95-011-00:on 950919,failed to Comply W/Ts SR for RCIC Sys Due to Analysis Deficiency That Resulted in Inadequate Surveillance Test Procedure.Surveillance Procedure Revised to Correct deficiency.W/951019 Ltr ML17291A9021995-07-0707 July 1995 LER 95-010-00:on 950609,HPCS DG Declared Inoperable Due to Discovery That TS Test Method Incomplete.Caused by Inadequate Testing Procedure.Test Procedure for HPCS DG Reviewed & Special Test Procedures written.W/950707 Ltr ML17291A9031995-07-0707 July 1995 LER 95-009-00:on 950607,inadvertent MSIV Closure Occurred During Surveillance Test Due to Poor Communication Between Test Team.Determined That MSIV Closure Not Valid Because Closure Not Triggered by Plant conditions.W/950707 Ltr ML17291A8501995-06-0808 June 1995 LER 95-006-01:on 950405,reactor Scram Occurred During Surveillance Testing Due to Protective Sys Relay Failure. Replaced Failed Relay Before Plant Startup ML17291A8101995-05-12012 May 1995 LER 95-008-00:on 940125,TS Wording Lead to Potential TS Violation.Caused by Lack of Clarity in Ts.Submitted Improved TS for Plant to Provide Addl clarity.W/950512 Ltr ML17291A7841995-05-0505 May 1995 LER 95-007-00:on 950222,emergency Diesel Start Occurred Due to Voltage Transient on BPA Grid.Confirmation Was Received at 17:51 H That Disturbance Had Originated in BPA Grid ML17291A7801995-05-0404 May 1995 LER 95-006-00:on 950405,main Turbine Trip Occurred During Performance of Surveillance Test Due to Protective Sys Relay Failed.Replaced Failed Relay Before Plant startup.W/950504 Ltr ML17291A7851995-05-0303 May 1995 LER 95-005-00:on 950222,inoperable IRM Had Been Relied Upon to Meet TS Requirements During Reactor Startup.Caused by Lack of Neutron Source to Test Instrumentation. Sys Knowledge Gained Will Be incorporated.W/950503 Ltr ML17291A7071995-03-25025 March 1995 LER 95-004-00:on 950226,malfunction in Main Turbine DEH Control Sys Caused All Four High Pressure Turbine Governor Valves to Rapidly Close.Caused by Blown Fuse.Suspected Faulty Circuit Card replaced.W/950325 Ltr ML17291A7011995-03-20020 March 1995 LER 95-002-00:on 950218,automatic Reactor Scram Occurred. Caused by Erroneous Positioning of Control During Performance of Scheduled Periodic Functional Test.Control repositioned.W/950320 Ltr 1999-07-20
[Table view] Category:RO)
MONTHYEARML17292B7421999-07-20020 July 1999 LER 99-001-00:on 990628,ESF Signal Closed All Eight MSIVs While Plant Was Shutdown.Caused by Failure of Relay RPS-RLY-K10D.Subject Relay Was Replaced & Tested on 990630. with 990720 Ltr ML17292B4451998-10-27027 October 1998 LER 98-012-01:on 980715,failure to Comply with Requirements of TS SR 3.8.4.7 Was Noted.Caused by Inadequate Work Practices.Training Session Was Held with Personnel.With 981027 Ltr ML17284A7561998-09-0303 September 1998 LER 98-013-00:on 980805,ESF Actuations Were Noted Due to Deenergization of Vital Electrical Bus SM-8.Caused by Inadequate Direction in Troubleshooting Plan.Will Conduct Training for Engineering Personnel.With 980903 Ltr ML17284A7571998-09-0202 September 1998 LER 98-014-00:on 980807,completion of TS 3.8.1.F Required Shutdown Due to Inoperability of EDG-2 Was Noted.Caused by Degraded Voltage Regulator for DG-2.Replaced Voltage Regulator & Associated Scrs.With 980902 Ltr ML17284A7551998-09-0202 September 1998 LER 98-015-00:on 980808,discovered Reactor Coolant Pressure Boundary Leak During Shutdown Conditions.Caused by Leakage from Socket Weld (Fwb 63) on Elbow Connection.Failed Piping Connection Was Replaced.With 980902 Ltr ML17284A7311998-08-17017 August 1998 LER 98-012-00:on 980716,determined That 24-month SR 3.8.4.7 Had Not Been Fulfilled within Specified Frequency.Caused by Inadequate Work Practices.License Requested & Received Enforcement Discretion Re Battery Svc test.W/980817 Ltr ML17284A7121998-07-23023 July 1998 LER 98-006-01:on 980520,discovered Discrepancies in Low Voltage Bus Calculations During Review of 10CFR50,App R Calculations for High Impedance Faults.Caused by Inadequate Work Practices.Implemented Procedural Changes ML17284A6951998-07-17017 July 1998 LER 98-011-00:on 980617,ECCS Pump Room Flooding Was Noted Due to FP Sys Pipe Break.Caused by Inadequate Design of FP Sys.Detailed Review of FP Sys Design Was Conducted. W/980717 Ltr ML17284A6961998-07-15015 July 1998 LER 98-010-00:on 980615,TS Required Shutdown Due to Inoperability of TIP Sys Isolation Valve Was Noted.Caused by Improper Installation of TIP Tubing.Reattached Affected Tubing & Inspected Other TIP tubing.W/980715 Ltr ML17284A6731998-07-0101 July 1998 LER 98-009-00:on 980606,nuclear Steam Supply Shutoff Sys Group 3 & 4 Isolations During Testing Was Noted.Caused by Procedural Deficiency.Counseled Individuals Involved in preparation.W/980701 Ltr ML17284A6651998-06-24024 June 1998 LER 98-007-00:on 980530,inadvertent Full Scram & Division 1 ECCS Injection Was Noted.Caused by Failure to Meet Mgt Work Practice Expectation When Encountering Deficient Procedure. Incident Review Board Convened to Review event.W/980624 Ltr ML17284A6641998-06-24024 June 1998 LER 98-008-00:on 980531,inadvertent Full Scram During RPV Leak Testing in Mode 4 Was Noted.Caused by Change in Mgt Techniques.Revised Procedures to Take Into Account Addl Water Head in Pressure Sensing lines.W/980624 Ltr ML17284A6631998-06-19019 June 1998 LER 98-006-00:on 980520,discovered Discrepancies in Low Voltage Bus Calculations During Review of App R Calculations for High Impedance Fault Analysis.Caused Indeterminate. Implemented Procedural Changes Involving Operator Action ML17284A6551998-06-0404 June 1998 LER 98-005-00:on 980506,potential for Failure of RHR Sys Valve to Close on Isolation Signal Was Noted.Caused by Design Deficiency.Caution Tag Was Placed on RHR-V-40 Control Switch to Inform Plant Operators of limitation.W/980604 Ltr ML17284A6421998-06-0101 June 1998 LER 98-004-00:on 980502,determined That Primary Containment Penetration Overcurrent Protection Does Not Meet Reg Guide 1.63 Requirements.Caused by Inadequate Design Changes. Installed Addl Fuse in RHR-MO-9 circuit.W/980601 Ltr ML17292B3281998-04-0909 April 1998 LER 98-002-00:on 980311,reactor Scram & Plant Transient Occurred,Due to Failed Closed Main Steam Isolation Valve. Caused by Loss of Pneumatic Actuating Supply Pressure. Problem Evaluation Request Written for Failure of MS-V-22D ML17292B3291998-04-0909 April 1998 LER 98-003-00:on 980311,WNP-2 Experienced SCRAM Signal as Result of Low Rpv.Caused by Less than post-SCRAM Operational Strategy for Resetting SCRAM Signal in Conditions.Changes in post-SCRAM Operational Strategy implemented.W/980409 Ltr ML17292B2661998-03-0404 March 1998 LER 98-001-00:on 980203,automatic Start of HPCS EDG Was Noted.Caused by Operator Error.Operations Crew Stabilized Plant at Approximately 75% Reactor Power & Investigation of Event Was initiated.W/980304 Ltr ML17292B1111997-11-10010 November 1997 LER 97-011-00:on 971010,HPCS Battery Charger Failed.Caused by Failure of a Phase Firing Control Circuit Board Due to Aging During 7 Yrs of Use.Hpcs Sys Was Immediately Declared inoperable.W/971110 Ltr ML17292B1151997-11-0707 November 1997 LER 97-010-00:on 970906,discovered That TS SR 3.4.5.1 for Identified Portion of RCS Total Leakage Would Not Be Able to Perform within Time Limits of SR 3.0.2.Caused by Inadequate Methods.Method of Meeting SR 3.4.5.1 Established ML17292B0641997-09-24024 September 1997 LER 97-004-01:on 970327,plant Operators Manually Scrammed Reactor as Required by TS Due to Indication of Entry Into Region a of power-to-flow Map.Caused by Inadequate Attention to Detail.Established Event Evaluation teams.W/970924 Ltr ML17292B0241997-08-18018 August 1997 LER 97-009-00:on 970717,discovered Error in Recently Performed Inservice Testing procedure,OSP-TIP/IST-R701. Caused by Procedure Inadequacy.Plant Procedure OSP/TIP/IST-R701 Will Be changed.W/970818 Ltr ML17292B0291997-08-15015 August 1997 LER 97-008-00:on 970716,wire Seal Used to Lock Containment Instrument Air Pressure Control valve,CIA-PCV-2B,found Not Intact.Cause of Misadjustment of CIA-PCV-2B Unknown.Event Will Be Communicated to Plant employees.W/970815 Ltr ML17292B0201997-08-15015 August 1997 LER 97-S01-00:on 970718,failure to Take Compensatory Measure for Inoperative Microwave Security Zone Occurred. Caused by Personnel Error.Training Will Be Conducted W/ Appropriate Members of Security force.W/970815 Ltr ML17292A9481997-07-23023 July 1997 LER 97-007-00:on 970611,voluntary Rept of Automatic Start of DG-1 & DG-2 Was Experienced.Caused by Undervoltage Condition on Electrical Busses SM-7 & SM-8.Circulating Water Pump CW-P-1C Control Switch Placed in pull-to-lock.W/970723 Ltr ML17292A9201997-06-26026 June 1997 LER 97-006-00:on 970527,non-performance of Surveillance Requirement 3.6.1.3.2 for Blind Fanges,Was Noted.Caused Because Misunderstanding of Intent of Specs.Added Five Structural Assemblies for SP.W/970626 Ltr ML17292A8331997-04-28028 April 1997 LER 97-004-00:on 970327,plant Operators Manually Scrammed Reactor as Required by TS Due to Entry Into Region a of power-to-flow Map Following Planned Trip of Single Mfp. Event Evaluation teams,established.W/970428 Ltr ML17292A8311997-04-28028 April 1997 LER 97-005-00:on 970327,valid Reactor Scram Signal Received Due to Low Water Level Condition During Preparations for SRV Testing.Caused by Risks & Consequences of Decisions Not Completely Identified.Restored Water level.W/970428 Ltr ML17292A8251997-04-21021 April 1997 LER 97-003-00:on 970320,notification of Noncompliance W/Ts as TS SRs for Response Time Testing Were Not Being Met for Specified Instrumentation in Rps,Pcis & Eccs.Requested Enforcement Discretion for One Time exemption.W/970421 Ltr ML17292A7431997-03-20020 March 1997 LER 97-002-00:on 970218,determined That Rod Block Monitor (RBM) Calibr Values Were Not Set IAW Tech Specs.Caused by Calibr Procedures Inadequacies.Revised & re-performed RBM Channel Calibr procedures.W/970330 Ltr ML17292A7401997-03-13013 March 1997 LER 97-001-00:on 970211,reactor Water Cleanup Sys Blowdown Flow Isolation Setpoint Was Slightly Above TS Allowable Valve Occurred Due to Calculation Error.Lds Fss LD-FS-15 LD-FS-16 Were Declared inoperable.W/970313 Ltr ML17292A6641997-01-22022 January 1997 LER 96-009-00:on 961220,miscalculation of Instantaneous Overcurrent Relay Settings Resulted in Inoperability of safety-related Equipment.Caused by Utilization of Inappropriate Design.Testing Was completed.W/970122 Ltr ML17292A6461997-01-0606 January 1997 LER 96-008-00:on 961205,failure to Comply with TS Action Requirement for Emergency Core Cooling Sys Actuation Instrumentation Occurred Due to Unidentified Inoperability Condition.Pmr initiated.W/970106 Ltr ML17292A6371996-12-19019 December 1996 LER 96-007-00:on 961122,electrical Breakers Were Not Seismically Qualified in Test/Disconnect Position.Circuit Breaker Mfg Did Not Consider Raced Out Breaker Position During Testing.Relocated Circuit breakers.W/961217 Ltr ML17292A4121996-08-0808 August 1996 LER 96-006-00:on 960709,average Power Range Monitor Rod Block Downscale Surveillance Not Performed Prior to Entry Into Mode 1.Caused by long-standing Misinterpretation of Requirements of Tss.Procedures revised.W/960808 Ltr ML17292A3801996-07-24024 July 1996 LER 96-004-00:on 960624,plant Was Manually Scrammed by Control Room Personnel Due to Reactor Water Level Transient Experienced During Testing of Digital Feedwater Sys.Caused by Programming Error.Sys Was corrected.W/960724 Ltr ML17292A3771996-07-24024 July 1996 LER 96-005-00:on 960624,determined Missed Surveillance Test Re Channel Check of Average Power Range Monitor.Caused by Inadequate Procedures.Revised Surveillance Procedure Re When APRM Checks Must Be performed.W/960724 Ltr ML17292A3641996-07-12012 July 1996 LER 96-003-00:on 960615,required Surveillance Test Not Performed When Required by TS 3.4.1.3.Caused by Inadequate Procedures.Implementing Surveillance Procedure & Reactor Plant Startup Procedures revised.W/960712 Ltr ML17292A3361996-06-20020 June 1996 LER 96-002-00:on 960504,critical Bus SM-8 Lost Power When Supply Breaker 3-8 Tripped.Caused by Personnel Error. Operators Counselled & Procedures revised.W/960620 Ltr ML17292A2861996-05-24024 May 1996 LER 96-001-00:on 960425,inadvertent ESF Actuations Occurred Due to Tripping of Temporary Power Supply to IN-3.Caused by Personnel Error.Operations Restored to IN-3 Loads & Reset ESF actuations.W/960524 Ltr ML17291B0891995-10-19019 October 1995 LER 95-011-00:on 950919,failed to Comply W/Ts SR for RCIC Sys Due to Analysis Deficiency That Resulted in Inadequate Surveillance Test Procedure.Surveillance Procedure Revised to Correct deficiency.W/951019 Ltr ML17291A9021995-07-0707 July 1995 LER 95-010-00:on 950609,HPCS DG Declared Inoperable Due to Discovery That TS Test Method Incomplete.Caused by Inadequate Testing Procedure.Test Procedure for HPCS DG Reviewed & Special Test Procedures written.W/950707 Ltr ML17291A9031995-07-0707 July 1995 LER 95-009-00:on 950607,inadvertent MSIV Closure Occurred During Surveillance Test Due to Poor Communication Between Test Team.Determined That MSIV Closure Not Valid Because Closure Not Triggered by Plant conditions.W/950707 Ltr ML17291A8501995-06-0808 June 1995 LER 95-006-01:on 950405,reactor Scram Occurred During Surveillance Testing Due to Protective Sys Relay Failure. Replaced Failed Relay Before Plant Startup ML17291A8101995-05-12012 May 1995 LER 95-008-00:on 940125,TS Wording Lead to Potential TS Violation.Caused by Lack of Clarity in Ts.Submitted Improved TS for Plant to Provide Addl clarity.W/950512 Ltr ML17291A7841995-05-0505 May 1995 LER 95-007-00:on 950222,emergency Diesel Start Occurred Due to Voltage Transient on BPA Grid.Confirmation Was Received at 17:51 H That Disturbance Had Originated in BPA Grid ML17291A7801995-05-0404 May 1995 LER 95-006-00:on 950405,main Turbine Trip Occurred During Performance of Surveillance Test Due to Protective Sys Relay Failed.Replaced Failed Relay Before Plant startup.W/950504 Ltr ML17291A7851995-05-0303 May 1995 LER 95-005-00:on 950222,inoperable IRM Had Been Relied Upon to Meet TS Requirements During Reactor Startup.Caused by Lack of Neutron Source to Test Instrumentation. Sys Knowledge Gained Will Be incorporated.W/950503 Ltr ML17291A7071995-03-25025 March 1995 LER 95-004-00:on 950226,malfunction in Main Turbine DEH Control Sys Caused All Four High Pressure Turbine Governor Valves to Rapidly Close.Caused by Blown Fuse.Suspected Faulty Circuit Card replaced.W/950325 Ltr ML17291A7011995-03-20020 March 1995 LER 95-002-00:on 950218,automatic Reactor Scram Occurred. Caused by Erroneous Positioning of Control During Performance of Scheduled Periodic Functional Test.Control repositioned.W/950320 Ltr 1999-07-20
[Table view] Category:TEXT-SAFETY REPORT
MONTHYEARML17284A9001999-10-31031 October 1999 Rev 0 to COLR 99-15, WNP-2 Cycle 15,COLR GO2-99-177, LER 99-S01-00:on 990903,failure to Take Compensatory Measure within Required Time Upon Failure of Isolation Zone Microwave Unit,Was Noted.Caused by Personnel Error.Provided Refresher Training on Compensatory Measures.With1999-10-0101 October 1999 LER 99-S01-00:on 990903,failure to Take Compensatory Measure within Required Time Upon Failure of Isolation Zone Microwave Unit,Was Noted.Caused by Personnel Error.Provided Refresher Training on Compensatory Measures.With ML17284A8941999-09-30030 September 1999 Monthly Operating Rept for Sept 1999 for WNP-2.With 991012 Ltr ML17284A8801999-08-31031 August 1999 Monthly Operating Rept for Aug 1999 for WNP-2.With 990910 Ltr ML17284A8691999-07-31031 July 1999 Monthly Operating Rept for July 1999 for WNP-2.With 990813 Ltr ML17292B7421999-07-20020 July 1999 LER 99-001-00:on 990628,ESF Signal Closed All Eight MSIVs While Plant Was Shutdown.Caused by Failure of Relay RPS-RLY-K10D.Subject Relay Was Replaced & Tested on 990630. with 990720 Ltr ML17292B7271999-06-30030 June 1999 Monthly Operating Rept for June 1999 for WNP-2.With 990707 Ltr ML17292B6961999-05-31031 May 1999 Monthly Operating Repts for May 1999 for WNP-2.With 990608 Ltr ML17292B6641999-04-30030 April 1999 Monthly Operating Rept for Apr 1999 for WNP-2.With 990507 Ltr ML17292B6391999-03-31031 March 1999 Monthly Operating Rept for Mar 1999 for WNP-2.With 990413 Ltr ML17292B5871999-02-28028 February 1999 Monthly Operating Rept for Feb 1999 for WNP-2.With 990311 Ltr ML17292B5571999-01-31031 January 1999 Monthly Operating Rept for Jan 1999 for WNP-2.With 990210 Ltr ML17292B5621999-01-31031 January 1999 Rev 1 to COLR 98-14, WNP-2 Cycle 14 Colr. ML17292B5341999-01-15015 January 1999 Part 21 Rept Re Incorrect Modeling of BWR Lower Plenum Vol in Bison.Defect Applies Only to Reload Fuel Assemblies Currently in Operation at WNP-2.BISON Code Model for WNP-2 Has Been Revised to Correct Error ML17292B5331999-01-15015 January 1999 Part 21 Rept Re XL-S96 CPR Correlation for SVEA-96 Fuel. Defect Applies Only to WNP-2,during Cycles 12,13 & 14 Operation.Evaluations of Defect Performed by ABB-CE ML17292B4791998-12-31031 December 1998 Washington Public Power Supply Sys 1998 Annual Rept. with 981215 Ltr ML17292B5351998-12-31031 December 1998 Monthly Operating Rept for Dec 1998 for WNP-2.With 990112 Ltr ML17292B5741998-12-31031 December 1998 WNP-2 1998 Annual Operating Rept. with 990225 Ltr ML17284A8231998-11-30030 November 1998 Monthly Operating Rept for Nov 1998 for WNP-2.With 981207 Ltr ML17284A8081998-10-31031 October 1998 Monthly Operating Rept for Oct 1998 for WNP-2.With 981110 Ltr ML17292B4451998-10-27027 October 1998 LER 98-012-01:on 980715,failure to Comply with Requirements of TS SR 3.8.4.7 Was Noted.Caused by Inadequate Work Practices.Training Session Was Held with Personnel.With 981027 Ltr ML17284A7831998-09-30030 September 1998 Monthly Operating Rept for Sept 1998 for WNP-2.With 981007 Ltr ML17284A7491998-09-10010 September 1998 WNP-2 Inservice Insp Summary Rept for Refueling Outage RF13 Spring,1998. ML17284A7561998-09-0303 September 1998 LER 98-013-00:on 980805,ESF Actuations Were Noted Due to Deenergization of Vital Electrical Bus SM-8.Caused by Inadequate Direction in Troubleshooting Plan.Will Conduct Training for Engineering Personnel.With 980903 Ltr ML17284A7571998-09-0202 September 1998 LER 98-014-00:on 980807,completion of TS 3.8.1.F Required Shutdown Due to Inoperability of EDG-2 Was Noted.Caused by Degraded Voltage Regulator for DG-2.Replaced Voltage Regulator & Associated Scrs.With 980902 Ltr ML17284A7551998-09-0202 September 1998 LER 98-015-00:on 980808,discovered Reactor Coolant Pressure Boundary Leak During Shutdown Conditions.Caused by Leakage from Socket Weld (Fwb 63) on Elbow Connection.Failed Piping Connection Was Replaced.With 980902 Ltr ML17284A7681998-08-31031 August 1998 Monthly Operating Rept for Aug 1998 for WNP-2.With 980915 Ltr ML17284A7311998-08-17017 August 1998 LER 98-012-00:on 980716,determined That 24-month SR 3.8.4.7 Had Not Been Fulfilled within Specified Frequency.Caused by Inadequate Work Practices.License Requested & Received Enforcement Discretion Re Battery Svc test.W/980817 Ltr ML17284A7261998-07-31031 July 1998 Monthly Operating Rept for July 1998 for WNP-2.W/980810 Ltr ML17284A7121998-07-23023 July 1998 LER 98-006-01:on 980520,discovered Discrepancies in Low Voltage Bus Calculations During Review of 10CFR50,App R Calculations for High Impedance Faults.Caused by Inadequate Work Practices.Implemented Procedural Changes ML17284A6951998-07-17017 July 1998 LER 98-011-00:on 980617,ECCS Pump Room Flooding Was Noted Due to FP Sys Pipe Break.Caused by Inadequate Design of FP Sys.Detailed Review of FP Sys Design Was Conducted. W/980717 Ltr ML17284A6961998-07-15015 July 1998 LER 98-010-00:on 980615,TS Required Shutdown Due to Inoperability of TIP Sys Isolation Valve Was Noted.Caused by Improper Installation of TIP Tubing.Reattached Affected Tubing & Inspected Other TIP tubing.W/980715 Ltr ML17284A6731998-07-0101 July 1998 LER 98-009-00:on 980606,nuclear Steam Supply Shutoff Sys Group 3 & 4 Isolations During Testing Was Noted.Caused by Procedural Deficiency.Counseled Individuals Involved in preparation.W/980701 Ltr ML17284A6751998-06-30030 June 1998 Ro:On 980617,flooding of RB Northeast Stairwell with Consequential Flooding of Two ECCS Pump Rooms.Caused by Inadequate Fire Protection Sys Design.Pumped Out Water from Affected Areas to Point Below Berm Areas of Pump Rooms ML17284A6641998-06-24024 June 1998 LER 98-008-00:on 980531,inadvertent Full Scram During RPV Leak Testing in Mode 4 Was Noted.Caused by Change in Mgt Techniques.Revised Procedures to Take Into Account Addl Water Head in Pressure Sensing lines.W/980624 Ltr ML17284A6651998-06-24024 June 1998 LER 98-007-00:on 980530,inadvertent Full Scram & Division 1 ECCS Injection Was Noted.Caused by Failure to Meet Mgt Work Practice Expectation When Encountering Deficient Procedure. Incident Review Board Convened to Review event.W/980624 Ltr ML17284A6631998-06-19019 June 1998 LER 98-006-00:on 980520,discovered Discrepancies in Low Voltage Bus Calculations During Review of App R Calculations for High Impedance Fault Analysis.Caused Indeterminate. Implemented Procedural Changes Involving Operator Action ML17284A6551998-06-0404 June 1998 LER 98-005-00:on 980506,potential for Failure of RHR Sys Valve to Close on Isolation Signal Was Noted.Caused by Design Deficiency.Caution Tag Was Placed on RHR-V-40 Control Switch to Inform Plant Operators of limitation.W/980604 Ltr ML17284A6421998-06-0101 June 1998 LER 98-004-00:on 980502,determined That Primary Containment Penetration Overcurrent Protection Does Not Meet Reg Guide 1.63 Requirements.Caused by Inadequate Design Changes. Installed Addl Fuse in RHR-MO-9 circuit.W/980601 Ltr ML17284A6491998-05-31031 May 1998 Rev 0 to COLR 98-14, WNP-2,Cycle 14 Colr. ML17292B4031998-05-31031 May 1998 Monthly Operating Rept for May 1998 for WNP-2.W/980608 Ltr ML17292B3921998-04-30030 April 1998 Monthly Operating Rept for Apr 1998 for WNP-2.W/980513 Ltr ML17292B3291998-04-0909 April 1998 LER 98-003-00:on 980311,WNP-2 Experienced SCRAM Signal as Result of Low Rpv.Caused by Less than post-SCRAM Operational Strategy for Resetting SCRAM Signal in Conditions.Changes in post-SCRAM Operational Strategy implemented.W/980409 Ltr ML17292B3281998-04-0909 April 1998 LER 98-002-00:on 980311,reactor Scram & Plant Transient Occurred,Due to Failed Closed Main Steam Isolation Valve. Caused by Loss of Pneumatic Actuating Supply Pressure. Problem Evaluation Request Written for Failure of MS-V-22D ML17292B3371998-03-31031 March 1998 Monthly Operating Rept for Mar 1998 for WNP-2.W/980409 Ltr ML17292B2641998-03-0404 March 1998 Performance Self Assessment,WNP-2. ML17292B2661998-03-0404 March 1998 LER 98-001-00:on 980203,automatic Start of HPCS EDG Was Noted.Caused by Operator Error.Operations Crew Stabilized Plant at Approximately 75% Reactor Power & Investigation of Event Was initiated.W/980304 Ltr ML17292B2911998-02-28028 February 1998 Monthly Operating Rept for Feb 1998 for WNP-2.W/980313 Ltr ML17284A7971998-02-17017 February 1998 Rev 28 to Operational QA Program Description, WPPSS-QA-004.With Proposed Rev 29 ML17292B3591998-02-12012 February 1998 WNP-2 Cycle 14 Reload Design Rept. 1999-09-30
[Table view] |
Text
~orna,za~mo Doimczm DiS aVrrow Svsrzrvr REGULATORY INFORMATION DISTRI BUTIO SYSTEM (RIDS)ACCESSIO>i!
HBR:9303020003 DOC.DATE: 93/02/22 NOTARIZED:
NO DOCKET FACIL:50-397 WPPSS Nuclear Project, Unit 2, Washington Public Powe.05000397 AUTH.NAME AUTHOR AFFILIATION POCHE,R.J.
Washington Public Power Supply System BAKER,J.W.
, Washington Public Power Supply System RECIP.NAME RECIPIENT AFFILIATION
SUBJECT:
LER 93-003-00:on 930121,de'termined that under certain ac.electrical distribution sys alignments, fault could result in unavailability of both offsite power sources.Caused by inadequate sys analysis.Delay.imes revised.W/930222 ltr.i!i i DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR ENCL SIZE: TITLE: 50'.73/50.9 Licensee Event Report (LER), ncident Rpt, etc.NOTES: RECIPIENT ID CODE/NAME ,PD5 LA CLIFFORDiJ COPIES LTTR ENCL 1 1 1 1 , RECIPIENT ID CODE/NAME PD5 PD COPIES LTTR ENCL 1 1 INTERNAL: ACNW AEOD/DOA AEOD/ROAB/DSP NRR/DE/EMEB NRR/DRCH/HHFBHE NRR/DRCH/HOLB NRR/DRSS/PRPB NRR/DSSA/SRXB RES/DSIR/EIB EXTERNAL EG&G BRYCE i J~H NRC PDR NSIC POORE,W.2 1 2 1 1 1 2 1 1 2 1 2 1 1 1 2 1 1 1 ACRS AEOD/DSP/TPAB NRR/DE/EELB NRR/DORS/OEAB NRR/DRCH/HICB NRR/DRIL/RPEB RRglB~SPLB REG FILE 02 R FILE 01 L ST LOBBY WARD NSIC MURPHY,G.A NUDOCS FULL'XT 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 NOTE TO ALL"RIDS" RECIPIENTS:
PLEASE HELP US TO REDUCE WASTE!CONTACT THE DOCUMENT CONTROL DESK, ROOM Pl-37 (EXT.504-2065)TO ELIMINATE YOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 32 ENCL 32 WASHINGTON PUBLIC POWER SUPPLY SYSTEM P.O.Box 968~3000 George Washington Way~Richland, Washington 99352 February 22, 1993 G02-93-041 Docket No.50-397 Document Control Desk U.S.Nuclear Regulatory Commission Washington, D.C.20555
SUBJECT:
NUCLEAR PLANT WNP-2, OPERATING LICENSE NPF-21 LICENSEE EVENT REPORT NO.93-003 Transmitted he'rewith is Licensee Event Report No.93-003 for the WNP-2 Plant.This report is submitted in response to the report requirements of 10CFR50.73 and discusses the items of reportability, corrective action taken, and action taken to preclude recurrence.
Sincerely, J.W.Baker WNP-2 Plant Manager (Mail Drop 927M)JWB/RJP/cgeh Enclosure CC: Mr.J.B.Martin, NRC-Region V Mr.R.Barr, NRC Resident Inspector (Mail Drop 901A, 2 Copies)INPO Records Center-Atlanta, GA Mr.D.L.Williams, BPA (Mail Drop 399)O~og/Q 93>>appo i'DR ADOC3 93PPa@CK pgpppa F'DR LICENSEE EVENT REPORT (LER)AGILITY NAME (I)Washin ton Nuclear Plant-Unit 2 DOCKET NUMB R ()PAGE (3)0 5 0 0 0 3 9 7 I OF ITLE (4)INADEQUATE COORDINATION OF PRIMARY UNDERVOLTAGE BUS TRANSFER LOGIC AND OVERCURRENT PROTECTION RESULTS IN POTENTIAL LOSS OF OFFSITE POWER AND DELAYED EMERGENCY POWER SOURCE AVAILABILITY EVENT DATE (5 MONTH OAY YEAR YEAR LER NUMBER;SEQUENTIAL
"'NUMBER 6)EVI 5 ION UHBER REPORT DATE (7 OTHER FACILITIES INVOLVED (8)CKE DAY MONTH YEAR FACILITY NAMES 05 HUMB R (S)0 I 2 I P ERAT ING DDE (9)DHER LEVEL 9 3 9 3 0 0 3 0 0 0 2 2 2 9 3 0 5 50.73(a)(2)(iv) 50.73(a)(2)(v) 50.73(a)(2)(vii) 50.73(a)(2)(viii)(A) 50.73(a)(2)(viii)(B) 50.73(a)(2)(x) o.4os(c)50.36(c)(1) 50.36(c)(2) 50.73(a)(2)(i) 50.73(a)(2)(ii) 50.73(a)(2)(iii) o.4o2(b)0.405(a)(1)(i) 0.405(a)(1)(ii) 20.405(a)(1)(iii) 20.405(a)(1)(iv) 20.405(a)(1)(v) 77.71(b)73.73(c)THER (Specify in Abstract elow and in Text.NRC Form 366A)HIS REPORT IS SUBHITTED PURSUANT TO THE REQUIREHENTS OF 10 CFR%1 (Check one or more of the following)
(11)3 LICENSEE CONTACT FOR THIS LER (12)R.J.PochT5, Licensing Engineer TELEPHONE HUMBER REA CODE 5 0 9 7 7-4 1 4 5 COMPLETE OHE LINE FOR EACH COMPONENT FAILURE DESCRIBED IH THIS REPORT (13)CAUSE SYSTEH COMPONENT HAHUFACTURER EPORTABLE 0 HPRDS CAUSE SYSTEH COMPOHEHT MANUFACTURER REPORTABLE TO NPRDS SUPPLEMENTAL REPORT EXPECTED (14)YES (If yes, complete EXPECTED SUBMISSION DATE)HO TRACt TTTO EXPECTED SUBMISSIOH MONTH DAY YEAR ATE (15)At approximately 1215 hours0.0141 days <br />0.338 hours <br />0.00201 weeks <br />4.623075e-4 months <br /> on January 21, 1993, it was determined that a deficiency involving coordination of protective relays associated with the AC electrical distribution system could result in plant operation that was not within the plant design bases.Under certain AC electrical distribution system alignments a fault on either 4.16 KV vital bus could have resulted in unavailability of both offsite power sources and delayed powering of the nonfaulted 4.16 KV vital bus from its associated Emergency Diesel Generator (EDG), WNP-2 has not experienced a bus fault that resulted in a loss of offsite power and/or delayed synchronization of the EDGs due to inadequate breaker coordination.
Consequently, the conditions described in this report did not have an adverse affect on safe operation of the plant, or the health and safety of plant personnel or the general public.The root cause of this condition was a deficiency involving inadequate analysis of undervoltage and overcurrent protective features on the vital 4.16 KV AC electrical distribution system.As corrective action, delay times associated with this breaker coordination problem were revised.Additionally, the Bus Short Circuit Current Calculation and the Relay Coordination Calculation will be reviewed and updated.
LICENSEE EVENT REPORT (LER)TEXT CONTINUATION ACILITY NAHE (1)Washington Nuclear Plant-Unit 2 DOCKET NUHBER (2)LER NUHBER (B)ear umber ev.No.AGE (3)3 003 0 2 F 7 ITLE (4)INADE(UATE COORDINATION OF PRIMARY UNDERVOLTAGE BUS TRANSFER LOGIC AND OVERCURRENT PROTECTION RESULTS IN, POTENTIAL LOSS OF OFFSITE POWER AND DELAYED EMERGENCY POWER SOURCE AVAILABILITY Plant n i i n Power Level-0%Plant Mode-3 (Hot Shutdown)Event De ri tion At approximately 1215 hours0.0141 days <br />0.338 hours <br />0.00201 weeks <br />4.623075e-4 months <br /> on January 21, 1993, it was determined that a deficiency in the medium voltage (4.16 KV)vital AC electrical distribution system could result in plant operation that was not within the plant design bases.This deficiency involved coordination of overcurrent protection relays and undervoltage bus transfer logic.Under certain electrical distribution system alignments, a persistent fault on either 4.16 KV vital bus could have resulted in unavailability of both offsite power sources and delayed powering of the nonfaulted 4.16 KV vital bus from its associated Emergency Diesel Generator (EDG).The medium voltage AC electrical distribution system has two divisionally separate and redundant vital busses, SM-7 and SM-8 (see attached sketch), that supply 4.16 KV power, to safety-related plant loads.These busses are typically aligned to the main generator via the normal station transformer (TR-Nl)when the main generator is on-line;however they can also be, and occasionally are, aligned to either the startup transformer (TR-S)or backup transformer (TR-B)during power operations.
Busses SM-7 and SM-8 are typically aligned to receive power'rom TR-S during plant startups and periods when the plant is shut down, with backup power available from TR-B.Design basis concerns involving loss of offsite power supplies and delayed powering of the nonfaulted vital bus existed under the previous'design when vital busses SM-7 and SM-8 were aligned to either TR-S or TR-B.Due to the cumulative effect of protective feature time delays associated with the transfer of loads from TR-S to TR-B, the most limiting condition with respect to delayed EDG output breaker closure resulted when the plant was initially aligned to TR-S.However, the design basis effect was essentially unchanged regardless of whether the vital busses were aligned to TR-S or TR-B at the start of the event.Vital busses SM-7 and SM-8 are both supplied from the same (Y)winding on TR-S.As a result, a fault on either vital bus when they are aligned to this transformer would cause an undervoltage condition on the 4.16 KV (Y)transformer winding that would be evidenced as an undervoltage condition on both vital busses.A bus fault cannot affect both vital busses when they are aligned to TR-Nl because each vital bus is powered from a separate winding when it is aligned to this transformer.
After sensing an undervoltage condition on SM-7 and SM-8, primary undervoltage protective devices (27)associated with these busses would have immediately initiated an automatic start of their respective EDG.With the previous undervoltage logic, vial bus source breakers aligned to TR-S would have tripped after approximately 2.0 seconds, initiating automatic transfer of the vital bus source from TR-S to TR-B.Due to LICENSEE EVENT REPORT (LER)TEXT CONTINUATION'GE (3)LER NUMBER (B)DOCKET NUMBER (2)0 5 0 0 0 3 9 7 FACILITY NAME (I)ear umber ev.No.Washington Nuclear Plant-Unit 2 3 OF 7 3 003 00 ITLE (4)INADEQUATE COORDINATION OF PRIMARY UNDERVOLTAGE BUS TRANSFER LOGIC AND OVERCURRENT PROTECTION RESULTS IN POTENTIAL LOSS OF OFFSITE POWER AND DELAYED EMERGENCY POWER SOURCE AVAILABILITY inadequate coordination of the overcurrent and undervoltage protective relay time delays, this transfer would have occurred before the overcurrent device on the incoming line to the faulted bus, which had an approximate
2.2 second
delay time, could energize its lock-out feature.This lock-out feature is designed to open the breaker on the incoming line to the faulted bus arid prevent other source breakers from closing onto the faulted bus.As a result, the faulted vital bus would not have been isolated, and would have transferred to the backup source, TR-B, instead.At this point, the safety bus source transfer logic (timing)would proceed as if the bus fault condition was a loss of power source event.There are two undervoltage relays on each of the incoming lines to backup source breakers B-7 and B-8.One relay senses bus undervoltage and trips its breaker at 69%or less of rated voltage.The other relay'provides a permissive to allow closure of it's source breaker if the secondary of TR-B is 94%or greater of rated voltage.The undervoltage transfer logic would have permitted backup source breakers B-7 and B-8 to close onto the vital busses approximately
4.0 seconds
after fault initiation.
Vital busses SM-7 and SM-8 share a common winding on TR-B.Consequently, if the bus fault had not cleared by this time, breakers B-7 and B-8 would have tripped open almost immediately due to the fault related undervoltage condition that would, exist on both SM-7 and SM-8.This breaker trip occurs immediately because undervoltage protective relays on the incoming lines from TR-B that are set to operate at 69%of rated voltage did not have a time delay.Again, because of a coordination deficiency involving time delays for undervoltage and overcurrent relays on the incoming line from TR-B, the overcurrent lock-out feature would not have prevented the TR-B supply breaker from closing onto the faulted bus.Instead, the undervoltage logic would have allowed the supply breaker from TR-B to repeatedly and unsuccessfully cycle onto the faulted bus until either the fault cleared or the supply breaker to the faulted bus failed, and could'have resulted=in the inability to successfully sequence the vital busses between TR-S to TR-B.Subsequently, if the SM-7 and SM-8 undervoltage time delay permissives to close the EDG output breakers were satisfied, and the EDGs were at rated speed and voltage (which normally occurs 8 seconds after start signal), transfer of the safety busses to their respective EDG would have been enabled approximately
5.0 seconds
after automatic transfer of both busses from TR-S to TR-B (7.0 seconds after fault initiation) if the undervoltage logic had not reset.However, transfer of the EDGs to SM-7 and SM-8 may not occur simultaneously.
If the source breaker for the nonfaulted bus closes onto TR-B before the source breaker for the faulted bus, it is possible that the undervoltage logic for the nonfaulted bus will reset.Resetting the undervoltage logic would extend the time delay permissive for transferring the EDG on the nonfaulted bus beyond design basis limits.For the faulted bus, if the primary undervoltage logic was not reset, the EDG output breaker would close after the original time delay permissive was satisfied and the EDG had obtained rated speed and voltage.EDG overcurrent relays (51V)would then pick up, provided there was no LOCA signal present, and LICENSEE EVENT REPORT LER)TEXT CONTINUATION h AGILITY NAHE (1)Washington Nuclear Plant-Unit 2 OOCKET NUHBER (2)0 5 0'0 0 3 9 7 LER NUHBER (8)ear umber ev.No.3 003 00 AGE (3)4 F-7 ITLE (4)INADEQUATE COORDINATION OF PRIMARY UNDERVOLTAGE BUS TRANSFER LOGIC,AND OVERCURRENT PROTECTION RESULTS IN POTENTIAL LOSS OF OFFSITE POWER AND DELAYED EMERGENCY POWER SOURCE AVAILABILITY energize the EDG lock-out relay.If a LOCA signal was present, the 51V relays are bypassed and the emergency generator would have eventually developed an internal fault due the heavy currents being supplied to the bus fault.The generator differential relays would then pick-up, thereby energizing the lock-out feature, shutting down the affected EDG, and resulting in loss of power to the faulted safety division.mmedia e orrec ive Ac i n As immediate corrective action, breaker B-7 was opened at 1330 hours0.0154 days <br />0.369 hours <br />0.0022 weeks <br />5.06065e-4 months <br /> on January 21, 1993, in order to provide separation between busses SM-7 and SM-8, and a design change was initiated to resolve breaker coordination deficiencies on SM-7 and SM-8.Bus separation was maintained until the design change could be implemented.
Further Evalua i n and rrec ive Ac ion A.F rther Evalu i n The breaker coordination issue described in this report was determined to be reportable pursuant to the requiiements of 10CFR50.72(b)(1)(ii)(B) as a condition that is outside the design basis of the plant because it could have resulted in loss of both offsite power sources and adversely affected the ability of the EDGs to start and synchronize within the time required.Necessary notification were made at 1302 hours0.0151 days <br />0.362 hours <br />0.00215 weeks <br />4.95411e-4 months <br /> on January 21, 1993.This condition is also reportable under 10CFR50,73(a)(2)(ii)(B).
2.Breaker coordination issues associated with current/voltage relaying-for SM-7 and SM-8 were identified as an area of potential concern during the WNP-2 Electrical Distribution Safety System Functional Inspection (EDSSFI)that was performed in January of 1992.When this inspection was performed, a review of the relay coordination calculation was already in progress, but had not been completed.
Also, update of the fault current calculation, which is'.necessary for evaluation of breaker coordination, was planned, but had not yet been performed.
The breaker coordination deficiency issue was not fully identified during the EDSSFI due to the complexity and scope of reviews necessary to evaluate the existing breaker coordination scheme.The breaker coordination was identified by a plant engineer during a review of electrical distribution system calculations that was being performed as part of an ongoing Electrical Calculation Improvement Program.
LICENSEE EVENT REPORT (LER)TEXT CONTINUATION AGILITY NAHE (1)Washington Nuclear.Plant-Unit 2 DOCKET NUHBER (2)0 5 0 0 0 3 9 7 LER NUHBER (8)Year Number ev.No.3 003 00 AGE (3)5 F 7 ITLE (4)INADEQUATE COORDINATION OF PRIHARY UNDERVOLTAGE BUS TRANSFER LOGIC AND OVERCURRENT PROTECTION RESULTS IN POTENTIAL LOSS OF OFFSITE POWER AND DELAYED EHERGENCY POWER SOURCE AVAILABILITY 3.li Coordination of overcurrent protective reiaying with the undervoltage transfer logic is required for vital electrical busses, but was, not adequately considered in the original AC electrical distribution design.In accordance with 10CFR50, Appendix A, Criterion 17;the design of the offsite power system is required to minimize the likelihood of simultaneous failure under operating and postulated accident and environmental conditions.
B.~R~Clge The root cause identified for this condition was a Plant/Equipment
-Design Configuration/Analysis category deficiency involving inadequate analysis.Previous analyses for the AC distribution system did not adequately consider coordination of the undervoltage and overcurrent protective relay schemes.This analysis inadequacy has existed since AC electrical distribution calculations were initially prepared by the architect/engineer.
C.~Fu her orrective Action'he following corrective actions have already been taken, or are in progress: f 1.A design change was implemented uncler BDC 93-0021-OA to increase the time delay for primary undervoltage relays for SM-7 and SM-8 and resolve breaker coordination issues associated with the supply from TR-S.This change will ensure that overcurrent relays are able to provide breaker trip and lock-out functions necessary to properly isolate a fault on either vital bus.Also, a time delay was provided for the 69 percent undervoltage protective feature associated with TR-B.There was previously no time delay associated with this protective feature.This time delay will provide coordination between undervoltage trips on the backup source breakers, B-7 (B-8);protective features on the associated line;and branch circuit overcurrent protection.
These design changes were completed for SM-7 and SM-8 on January 25, 1993, at 0948 hours0.011 days <br />0.263 hours <br />0.00157 weeks <br />3.60714e-4 months <br /> and 2355 hours0.0273 days <br />0.654 hours <br />0.00389 weeks <br />8.960775e-4 months <br />, respectively.
2.'lectrical distribution system calculations are currently being reviewed and updated on an ongoing basis under the Electrical Calculation Improvement Program.The condition described in this report involved the Bus Short Circuit Current Calculation and the Relay Coordination Calculation.
Review and update of these calculations is expected by April 30, 1993.
LICENSEE EVENT REPOR ER)TEXT CONTINUATION ACILITY NAHE (i)Washington Nuclear Plant-Unit 2 DOCKET NUHBER (2)0 5 0 0 0-3 9 7 ev.No.3 03 0 LER NUHBER (6)ear umber AGE (3)6 F 7 1TLE (4)INADEQUATE COORDINATION OF PRIMARY UNDERVOLTAGE BUS TRANSFER LOGIC AND OVERCURRENT PROTECTION RESULTS IN POTENTIAL LOSS OF OFFSITE POWER AND DELAYED EMERGENCY-POWER SOURCE AVAILABILITY
~fi if'NP-2 has not experienced a bus fault that resulted in a loss of offsite power and/or delayed closure of EDG,output breakers due to inadequate breaker coordination.
Consequently, the conditions described in this report did not have an adverse affect on safe operation of the plant, or the health and safety of plant personnel or the general public.Additionally, the condition described in this report can only affect both vital power divisions when plant loads are aligned to offsite power sources via TR-S or TR-B.This alignment is typically used only when the main generator is off-line and the plant is not at a substantial power level.Therefore, if a persistent fault condition had existed on SM-7 or SM-8 when the plant was aligned to TR-S or TR-B its significance would have been minimized.
imil r Even Two previous events involving inadequate coordination of undervoltage protection have been reported in LERs89-034 and 92-027.These previous events resulted from'design deficiencies involving inadequate coordination of protective features for 480 volt Motor Control Centers, and did not involve coordination of protective features for the 4.16 KV vital busses.EIIS Informati n EIIS Reference AC Distribution System Transformers (TR-N1, TR-B, TR-S, TR-Ml/2/3/4)
Breakers Safety-Related Busses (SM-7 8c SM-8)Emergency Diesel Generators (EDG)Main Generator$y~tem LK LK LK EB ED TB~Com non TD BKR BU DG GEN1 LICENSEE EVENT REPOR LER)TEXT CONTINUATION AGILITY NAHE (I)Washington Nuclear Plant-Unit 2 DOCKET NUHBER (2)0 5 0 0 0 3 9 7 LER NUHBER (B)ear umber ev.No.3 03 00 AGE (3)7 F 7 ITLE (4)INADEQUATE COORDINATION OF PRIMARY UNDERVOLTAGE BUS TRANSFER LOGIC AND OVERCURRENT PROTECTION RESULTS IN POTENTIAL LOSS OF OFFSITE POWER AND DELAYED EMERGENCY.
POWER SOURCE AVAILABILITY 500 KV E-TR-M1/2/3/4 25 KV MA I N GENERATOR 4.16 KV.E-TR-N1 4.16 KV E-TR-S 4.16 KV Y X 6.9 KV N1-1 S-1 N1-2 S-2 N1-3 SM-1 SM-2 SM-3 5-3 1-7'4 51 E-TR-8 115 KV I 27 27 4.16 KV 8-7 94%V 69%V 7 27'-B 8-3 69%V 99%V 7 27 7-DG1 SM-8 8-DG2 51 DG1-7 DG2-8 EDG-1 AC Distribution System Diagram (For Information Only)EDG-2