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Category:REPORTABLE OCCURRENCE REPORT (SEE ALSO AO LER)
MONTHYEARML20205C4171999-03-25025 March 1999 Special Rept 99-02:on 801027,Commission Approved for publication,10CFR50.48 & 10CFR50 App R Delineating Certain Fire Protection Provisions for Nuclear Power Plants Licensed to Operate Prior to 790101.Team Draft Findings Reviewed ML20207K2051999-03-0505 March 1999 Special Rept 99-01:on 990128,DG Tripped After 2 H of Operation During Loaded Operation for Monthly Test.Caused by Several Components That Were Degraded or Had Intermittent Problems.Parts Were Replaced & Initial Run Was Performed ML20196D4171998-11-24024 November 1998 Special Rept 98-02:on 981112,failure to Implement Fire Watches in Rooms Containing Inoperable Fire Barrier Penetrations,Was Determined.Repair of Affected Fire Barriers in Progress ML20151W3521998-09-0808 September 1998 Special Rept 98-01:on 980819,maint Could Not Be Performed on FPS Due to Isolation Boundary Leakage.Caused by Inadequate Info Provided in Fire Impairment Plan.Isolated Portion of FPS Was Returned to Svc ML20148A9881997-05-0101 May 1997 Special Rept 96-04-02:on 970429,groundwater Level at Well Mk GWA-2 Was in Alarm for 7 Days.Caused by Precipitation During Previous Week.Verified That No Other Groundwater Monitoring Instruments Were in Alarm ML20137P0711997-04-0707 April 1997 Special Rept 97-01:on 970226,Peak Accelerometer,1MIMT-5030, Removed Under WO 95092624 as Part of SG Replacement Project. Accelerometer Will Return to Svc Prior to Unit 1 Startup ML20133L6051997-01-0909 January 1997 Special Rept 96-04,Rev 1,groundwater Level at Well Mk GWA-2 Monitored by 2WZLS5060 Was in Alarm for 7 Days.Verified That No Other Groundwater Monitoring Instruments in Alarm ML20134N0261996-11-14014 November 1996 Special Rept:On 961006,groundwater Alarm Was Received & Entered in TS Action Item List for Tracking.Field Survey of Surrounding Areas Was Performed to Verify That No Water Was Percolating to Surface That Would Indicate Pipe Leak ML20116K0331996-08-0909 August 1996 Special Rept 96-03:on 960611,identified Broken Secondary Contact Blocks.Caused by Mishandling of Breakers or over- Torquing of Mounting Bolts.Breaker 2BYA Repaired,Tested & re-installed in Cabinet ML20086G9601995-07-12012 July 1995 Special Rept 95-002:on 950612,turbocharger Failed,As Detected by Excessive Noise & Vibration.Engine Subsequently Secured.Damaged Components Replaced & DG 2A Returned to Operable Status ML20080G4421995-02-0303 February 1995 Special Rept 95-01:on 950104,personnel on Unit 2 Operating in Solid Condition During Fill & Vent of Nc Sys ML20078R7651994-12-15015 December 1994 Special Rept 94-06:on 941012,fatigue Usage to SI Sys Piping by Manually Initiating Flow Through B Cold Leg from Fwst During Testing for Valve 1NI-71 Intentionally Increased. Startup of Facility Discontinued to Repair Valve ML20078L6571994-11-22022 November 1994 Special Rept SR-94-05:on 941024,Channel 3 of Vibration & Loose Parts Monitoring Sys Declared Inoperable Due to Noise.Channel 3 of V&Lpm Will Be Repaired Under WR 94043758 or Replaced by Nsm MG-12096 During Outage 1EOC10 ML20073C2451994-09-14014 September 1994 Special Rept 94-004:on 940821,valid Failure of DG 1A Occurred Due to Failure of Series Boost exciter-regulator (Voltage Regulator).Isolation Transformer T54 & Current Transformers CT1,CT2 & CT3 Will Be Inspected ML20065K2501994-04-15015 April 1994 Special Rept 94-03:on 940210,during Testing PORV Observed to Hang Open in Absence of air-assisted Closure.Caused by Incomplete Testing of Porvs.Compensatory Measures Reanalyzed & Reestablished Addressing Fire & Security Issues ML20064K0311994-03-15015 March 1994 Special Rept 94-01:on 940215,DG 2A Tripped W/Low Lube Oil Pressure Indication During Routine Surveillance Test.Caused by Pressure Too Low in Bldg Up in Sensing Lines.Test Satisfactorily Repeated ML20058M4281993-09-27027 September 1993 Special Rept 93-09:on 930920,notifies of Alarm Condition Showing Alert on Ground Water Level Outside 1A DG Room.Work Order 93063348 Initiated by Wc Personnel to Have Iae Personnel Check Operation & Calibr ML20056F8561993-08-23023 August 1993 Special Rept 93-06:on 930405,discovered Debris on Unit 1 Lower Core Plate.Four Other Unidentified Objects Noted During Video Insp of Lower Core Plate ML20126B5051992-12-15015 December 1992 Inplant Review Rept 92-20,special Rept Re Postulated Scenario That Could Introduce Air Into AFW Suction Piping. Caused by Functional Design Deficiency.Setpoints of Affected Pressure Switches Increased ML20106D7401992-10-0909 October 1992 RO 92-19:on 920804,discovered That Drive Shaft on Pump 1MNVPU0046 Was Rotating in Opposite Direction than Specified on Pump Casing.Caused by Mgt Deficiency.Motor Leads of Subj Pump Reconfigured to Provide Correct Pump Shaft Rotation ML20127E0191992-09-0909 September 1992 Special Rept:On 920421,unusual Event Declared Because Unit 1 Train B of Ssps Inoperable Due to Defective Circuit Card within Ssps.Failed Train B Ssps Circuit Board Replaced & Appropriate Procedures to Be Evaluated ML20101T9441992-07-13013 July 1992 Special Rept for Inplant Review 92-10:on 920610 No Mention Made on Work List of Vent Path Through SG 1B for Incoming SG Crews.Caused by Deficient Communication.Turnover Sheet Established to Document Existing Vent Path Status ML20101P5581992-07-0303 July 1992 In-Plant Review Rept 92-09:on 920619,setpoint Problems Noted W/Ts & Selected Licensee Commitment Values for Listed Field Data.Caused by Discrepancies W/Groundwater Level Monitoring Portion of Wz Sys.Ts Monitor Logged in Unit 2 Logbook ML20086Q1101991-12-20020 December 1991 Voluntary Special Rept 91-23:on 911008,reactor Vessel Lower Internals Contacted Reactor Vessel During Removal.Caused by Inappropriate Operator Action & Mgt Deficiency.Recovery Plan Developed Re Insp of Lower Internals & Refueling Canal ML20086H9431991-12-0404 December 1991 Special Rept 91-24:on 911104-29,concerns Noted Re Possible Leakage of Containment Spray Sys Check Valves Into Annulus, Causing Offsite Radioactive Dose.Caused by Design Deficiency.Check Valve Installed Downstream of Piping ML20091C0851991-08-0101 August 1991 Special Rept PIR 1-M91-0113:on 910616,diesel Engine Cooling Water Leak Discovered on Diesel Generator 1A at Discharge Flange on Intercooler End Bell Cover.Caused by Poor Casting Quality.New Covers Will Be Installed ML20081F7371991-06-0404 June 1991 Rev 1 to Special Rept 91-11 Dtd 910411:on 910215,turbine Driven Auxiliary Feedwater Pumps Automatically Started. Caused by Deficient Communication & Lack of Attention to Detail.Pump Speed Reduced & Discharge Valves Closed ML20062E7991990-11-14014 November 1990 Special Rept:On 901011,turbine Driven Auxiliary Feedwater Pump Declared Inoperable W/O Having Made Security Notification.Caused by Inappropriate Action ML20055G2161990-07-12012 July 1990 Ro:On 900602,discovered That Channel 7 of Vibration & Loose Parts Monitor Sys Had Low Noise Level.Probably Caused by Bad or Damaged Sensor Cable.Definite Cause of Failure Undetermined.Sys Scheduled to Be Replaced ML20246F7081989-07-0303 July 1989 Special Rept:On 890601,diesel Generator 1A Shut Down Due to Lack of Oil Flow.Due to Test Being Performed,Normal Stop Would Not Shutdown Engine.New Oil Added & Pumps Primed. Turbocharger Mods Under Investigation ML20247N8841989-05-30030 May 1989 Special Rept:On 890418,vibration & Loose Parts Monitor Failed.Caused by Damaged Cables to Sensors on Each Affected Channel.Vibration & Loose Parts Monitor Will Be Repaired During Next Refueling Outage After New Replacement Received ML20244C6731989-04-0606 April 1989 Special Rept:On 890225,operations Personnel Discovered That Channel 8 of Vibration & Loose Parts Monitoring Sys Had Low Noise Level.Investigation Scheduled to Be Completed During Unit 1 Tube Leak Outage ML20196E8241988-12-0505 December 1988 Special Rept:On 881205,diesel Generator 1B Experienced Invalid Test Failure.Caused by Improper Adjustment of Voltage Regulator Due to Personnel Error.Operations Mgt Will Cover Incident W/Representative from Each Shift ML20196B5211988-11-29029 November 1988 Special Rept:On 881030,Diesel Generator 1B Experienced Invalid Test Failure During Start Attempt 602.Applicable Procedures for Diesel Generator Testing Reviewed & Revised If Necessary ML20195H4901988-11-16016 November 1988 Special Rept:On 881017,diesel Generator 1A Started for Operability Test & Subsequently Tripped.Caused by Loose Wire on Jacket Pump Discharge Pressure Switch.Wire Reterminated & Pressure Switch Calibr ML20205G3401988-10-24024 October 1988 Special Rept:On 880916,Tech Spec 3.7.14.a Violated.Caused by Standby Shutdown Facility Being Inoperable for More than 7 Days Due to Transfer Canal Isolating & Draining Utilizing Weir Gate.Special Order 88-13 Issued ML20151R0971988-07-27027 July 1988 Special Rept:On 880627,diesel Generator 1A Failed to Start within 11 S.Caused by Missing Drain Valve on Starting Air Filter Housing on Right Bank Side of Diesel Engine.Work Request Written to Replace Filter Housing ML20151F4911988-07-22022 July 1988 Special Rept:On 880519,diesel Generator 1A Started for Operability Test & After Operating for 10 Minutes, Automatically Stopped & Declared Inoperable.Caused by Failure to Maintain Lubricating Level in Valve 1LD-7 ML20195J3601988-06-22022 June 1988 Special Rept:On 880323,Train a Safety Injection & Main Steam Sys Isolation Signals Received from Unknown Fault Inside Train a Solid State Protection Sys Logic Cabinet.Cause of Fault Could Not Be Isolated.Cabinet Returned to Svc ML20195J6161988-06-20020 June 1988 Advises That Special Rept Re Diesel Generator 1A Incident on 880519 Will Be Submitted by 880708 Instead of 880620 Due to Unresolved Concerns ML20195G2171988-06-17017 June 1988 Special Rept:On 880518,diesel Generator 1B Experienced Valid Failure.Caused by Fuel & Vol of Trapped Air Shook Debris Loose from Engine Mounted Duplex Fuel Filter.Filter Cartridges Replaced.Preventative Maint Procedure Revised ML20151C7691988-04-0404 April 1988 Ro:Change of Commitment Submitted Re Diesel Generator Turbocharger Rotor Assembly Replacement.Turbocharger Inlet Casings Replaced on All Four Engines W/New Design.Dye Penetrant Testing Will Continue to Be Performed ML20147F4311988-03-0303 March 1988 Special Rept:On 880123,Channels 3,4 & 8 of Vibration & Loose Parts Monitor Had Unusual Noise Level.Cause Not Determined Due to Number of Possible Failures & Location of Components within Plants.Monitor Will Be Repaired During 1988 Outage ML20237D1341987-12-14014 December 1987 Special Rept:On 871108,safe Shutdown Facility RCS Wide Range Transmitter Out of Calibr.Instrument Could Not Be Calibrated.Requisition Initiated for Replacement Transmitter ML20236Q1621987-11-13013 November 1987 Special Rept:On 870816,malfunction of Main Turbine Generator Controls Caused Rapidly Decreasing Main Steam Line Pressure Triggering Safety Injection/Reactor Trip.Safety Injection & Unusual Event Terminated & Repairs Completed on 870821 ML20214S5421987-06-0808 June 1987 Special Rept:On 870503,pressurizer PORV 2NC-34A Automatically Opened Due to Pressure Transient in Rcs.Cause Not Determined.Charging & Letdown Flow Adjusted & Procedures Re Allowable Setpoint Range Revised ML20214G7301987-05-13013 May 1987 Special Rept:On 870407 & 08,complete 18-month Insp Required for Standby Shutdown Diesel Generator Determined Not to Have Been Performed on Time.Caused by Personnel Error.Work Request Will Be Issued Prior to 18-month Due Dates ML20213H0591987-05-0808 May 1987 Ro:On 870409,personnel Discovered Monthly Channel Checks on Reactor Vessel Level Instrumentation Sys Wide Range Instrumentation Not Performed,Per Tech Specs.Ler Will Be Submitted by 870518 ML20214J1591986-11-21021 November 1986 Ro:On 861029,valves in ECCS Declared Inoperable.Caused by Rotork Motor Switch Settings.Ler for Incident Will Be Delayed Until 861219 to Allow Testing & Evaluation of Units ML20203J6551986-07-28028 July 1986 Ro:On 860626 & 27,small Cylindrical Objects Observed on Upper Core Baffle & in Vicinity of Upender,Respectively.On 860629,objects Confirmed to Be Spent Fuel Pellets.Pellets Vacuumed from Core & Upender 1999-03-05
[Table view] Category:TEXT-SAFETY REPORT
MONTHYEARML20217G7951999-09-30030 September 1999 Monthly Operating Repts for Sept 1999 for McGuire Nuclear Station,Units 1 & 2 ML20217F3661999-09-22022 September 1999 Rev 18 to McGuire Unit 1 Cycle 14 Colr ML20212D1911999-09-20020 September 1999 SER Accepting Exemption from Certain Requirements of 10CFR50,App A,General Design Criterion 57 Closed System Isolation Valves for McGuire Nuclear Station,Units 1 & 2 ML20216E8851999-08-31031 August 1999 Monthly Operating Repts for Aug 1999 for McGuire Nuclear Station,Units 1 & 2 ML20211B1281999-08-31031 August 1999 Dynamic Rod Worth Measurement Using Casmo/Simulate ML20217G8101999-08-31031 August 1999 Revised Monthly Operating Repts for Aug 1999 for McGuire Nuclear Station,Unit 1 & 2 ML20211G5261999-08-24024 August 1999 SER Accepting Approval of Second 10-year Interval Inservice Insp Program Plan Request for Relief 98-004 for Plant,Unit 1 ML20211F3441999-08-17017 August 1999 Updated non-proprietary Page 2-4 of TR DPC-NE-2009 ML20210S2371999-07-31031 July 1999 Monthly Operating Repts for July 1999 for McGuire Nuclear Station,Units 1 & 2 ML20216E8951999-07-31031 July 1999 Revised Monthly Operating Repts for July 1999 for McGuire Nuclear Station,Units 1 & 2 ML20209E4361999-07-0909 July 1999 SER Agreeing with Licensee General Interpretation of TS LCO 3.0.6,but Finds No Technical Basis or Guidance That Snubbers Could Be Treated as Exception to General Interpretation ML20196K6631999-07-0707 July 1999 Safety Evaluation Supporting Licensee 990520 Position Re Inoperable Snubbers ML20209H1631999-06-30030 June 1999 Monthly Operating Repts for June 1999 for McGuire Nuclear Station,Units 1 & 2 ML20210S2491999-06-30030 June 1999 Revised Monthly Operating Rept for June 1999 for McGuire Nuclear Station,Units 1 & 2 ML20209H1731999-05-31031 May 1999 Revised Monthly Operating Rept for May 1999 for McGuire Nuclear Station,Units 1 & 2 ML20206T4771999-05-31031 May 1999 Rev 3 to UFSAR Chapter 15 Sys Transient Analysis Methodology ML20196L1881999-05-31031 May 1999 Non-proprietary Rev 1 to DPC-NE-3004, Mass & Energy Release & Containment Response Methodology ML20195K3691999-05-31031 May 1999 Monthly Operating Repts for May 1999 for McGuire Nuclear Station,Units 1 & 2 ML20206N3511999-05-11011 May 1999 Safety Evaluation Accepting Licensee Response to GL 96-05, Periodic Verification of Design-Basis Capability of Safety- Related Movs ML20195K3761999-04-30030 April 1999 Revised MORs for Apr 1999 for McGuire Nuclear Station,Units 1 & 2 ML20206R0891999-04-30030 April 1999 Monthly Operating Repts for Apr 1999 for McGuire Nuclear Station,Units 1 & 2 ML20205L2341999-04-0505 April 1999 SFP Criticality Analysis ML20206R0931999-03-31031 March 1999 Revised Monthly Repts for Mar 1999 for McGuire Nuclear Station,Units 1 & 2 ML20205P8991999-03-31031 March 1999 Monthly Operating Repts for Mar 1999 for McGuire Nuclear Station,Units 1 & 2 ML20205C4171999-03-25025 March 1999 Special Rept 99-02:on 801027,Commission Approved for publication,10CFR50.48 & 10CFR50 App R Delineating Certain Fire Protection Provisions for Nuclear Power Plants Licensed to Operate Prior to 790101.Team Draft Findings Reviewed ML20207K2051999-03-0505 March 1999 Special Rept 99-01:on 990128,DG Tripped After 2 H of Operation During Loaded Operation for Monthly Test.Caused by Several Components That Were Degraded or Had Intermittent Problems.Parts Were Replaced & Initial Run Was Performed ML20204C8911999-02-28028 February 1999 Monthly Operating Repts for Feb 1999 for McGuire Nuclear Station,Units 1 & 2 ML20205P9021999-02-28028 February 1999 Revised Monthly Operating Repts for Feb 1999 for McGuire Nuclear Station,Units 1 & 2 ML20204C8961999-01-31031 January 1999 Revised Monthly Operating Repts for Jan 1999 for McGuire Nuclear Station,Units 1 & 2 ML20199E0301998-12-31031 December 1998 Monthly Operating Repts for Dec 1998 for McGuire Nuclear Station,Units 1 & 2 ML20216F9931998-12-31031 December 1998 Piedmont Municipal Power Agency 1998 Annual Rept ML20198A4481998-12-11011 December 1998 Safety Evaluation Concluding That for Relief Request 97-004, Parts 1 & 2,ASME Code Exam Requirements Are Impractical. Request for Relief & Alternative Imposed,Granted ML20198D7561998-11-30030 November 1998 Monthly Operating Repts for Nov 1998 for McGuire Nuclear Station,Units 1 & 2 ML20199E0491998-11-30030 November 1998 Revised Monthly Operating Rept for Nov 1998 for McGuire Nuclear Station,Units 1 & 2 Re Personnel Exposure ML20199E9651998-11-24024 November 1998 Rev 1 to ATI-98-012-T005, DPC Evaluation of McGuire Unit 1 Surveillance Weld Data Credibility ML20196D4171998-11-24024 November 1998 Special Rept 98-02:on 981112,failure to Implement Fire Watches in Rooms Containing Inoperable Fire Barrier Penetrations,Was Determined.Repair of Affected Fire Barriers in Progress ML20196G0581998-11-0606 November 1998 Rev 17 to COLR Cycle 13 for McGuire Unit 1 ML20196G0761998-11-0606 November 1998 Rev 15 to COLR Cycle 12 for McGuire Unit 2 ML20198D7771998-10-31031 October 1998 Revised Monthly Operating Rept for Oct 1998 for McGuire Nuclear Station,Units 1 & 2 ML20195E5961998-10-31031 October 1998 Monthly Operating Repts for Oct 1998 for McGuire Nuclear Station,Units 1 & 2 ML20154L6251998-09-30030 September 1998 Monthly Operating Repts for Sept 1998 for McGuire Nuclear Station,Units 1 & 2 ML20195E6021998-09-30030 September 1998 Revised Monthly Operating Rept for Sept 1998 for McGuire Nuclear Station,Units 1 & 2 ML20154B4131998-09-22022 September 1998 Rev 0 to ISI Rept for McGuire Nuclear Unit 1 Twelfth Refueling Outage ML20151W3521998-09-0808 September 1998 Special Rept 98-01:on 980819,maint Could Not Be Performed on FPS Due to Isolation Boundary Leakage.Caused by Inadequate Info Provided in Fire Impairment Plan.Isolated Portion of FPS Was Returned to Svc ML20154L6321998-08-31031 August 1998 Rev 1 to MOR for Aug 1998 for McGuire Nuclear Station,Unit 1 ML20153B3741998-08-31031 August 1998 Monthly Operating Repts for Aug 1998 for McGuire Nuclear Station,Units 1 & 2 ML20236U1601998-07-31031 July 1998 Non-proprietary DPC-NE-2009, DPC W Fuel Transition Rept ML20237B2381998-07-31031 July 1998 Monthly Operating Repts for July 1998 for McGuire Nuclear Station,Units 1 & 2 ML20153B3931998-07-31031 July 1998 Revised Monthly Operating Repts for Jul 1998 for McGuire Nuclear Station,Units 1 & 2 ML20236P0451998-07-0808 July 1998 Part 21 Rept Re non-conformance & Potential Defect in Component of Nordberg Model FS1316HSC Standby Dg.Caused by Outer Spring Valves Mfg from Matl That Did Not Meet Specifications.Will Furnish Written Rept within 60 Days 1999-09-30
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DUKE POWER GOMPANY P.O. box G3189 CHARLOTrE, N.C. 28949 HAL B. R'CKER Tatzenown vuos caussasse (704)373-4531 stotaan enamectioso April 1, 1987 U.S. Nuclear Regulatory Connaission Document Control Desk Washington, D.C. 20555
Subject:
McGuire Nuclear Station Docket No. 50-370 Diesel Generator Failure Special Recart Technical Specification 3.8.1.1.3 and 6.9.2 Gentlemen:
4 Please find attached a Diesel Generator failure report submitted pursuant to Technical Specification (T.S.) 6.9.2 as specified in T.S. 4.8.1.1.3. The report I
concerns a valid failure of Diesel Generator 2A due to the failure of a capacitor.
This event is considered insignificant with respect to the health cnd safety of the public.
Very truly yours, L
Qc Hal B. Tucker SEL/19/jgm I Attachment xc: Dr. J. Nelson Grace American Nuclear Insurers Regional Administrator, Region II c/o Dottie Sherman, ANI Library U.S. Nuclear Regulatory Commission The Exchange, Suite 245 101 Marietta St., NW, Suite 2900 270 Farmington Avenue Atlanta, GA 30323 Farmington, CT 06032 Mr. Darl Hood INPO Records Center U.S. Nuclear Regulatory Commission Suite 1500 '-
Office of Nuclear Reactor Regulation 1100 circle 75 Parkway Washington, D.C. 20555 Atlanta, CA 30339 Mr. W.T. Orders M&M Nuclear Consultants l NRC Resident Inspector 1221 Avenue of the Americas McGuire Nuclear Station New York, NY 10020 8704070406 070401 PDR ADOCK 00000370 S I PDR
Diesel Generator 2A Valid Failure Due to a Failed Capacitor in the Exciter-Voltage Regulator INTRODUCTION:
On March 2,1987, at 0910, during the performance of an operability test, Diesel Generator (D/G) 2A failed to achieve 4160 VAC within 11 seconds as required by Technical Specification (TS) 3.8.1.1.2. This was a valid test and was the sixth valid failure of a Unit 2 D/G in the last one hundred valid tests. The cause of the failure was investigated and a circuit board in the Exciter-Voltage Regulator was replaced. The baseline and operability tests were then performed successfully and the D/G was declared operable at 2250 on March 3. Later, while evaluating the circuit board in the shop, a capacitor in the output filter circuit for the Exciter-Voltage Regulator was discovered to have failed which would have slowed the generator field flashing control circuit.
Unit 2 was in Mode 1, Power Operation, at 100% power at the time of this incident.
This incident has been attributed to the failure of the capacitor.
BACKGROUND:
Each unit at McGuire Nuclear Station has two independent D/Gs which, as a part of the Essential Power System, provides standby AC power to the equipment required to safely shut down the reactor in the event of the loss of normal power. The D/Gs also supply power to the safeguard equipment as required during a major accident coincident with a loss of normal power (blackout).
Each D/G unit consists of a sixteen cylinder Nordberg diesel engine connected to a 4 KV generater manufactured by Electric Products Division of Portec Inc.
A governor and an Exciter-Voltage Regulator are interconnected to control the D/G in both automatic and manual modes. An emergency override feature func-tions to reset the manual mode to the automatic mode when an Engineered Safety Features (ESF) actuation occurs. When the D/G is shut down, the governor and Exciter-Voltage Regulator are automatically reset to the automatic mode and to the correct emergency use settings.
The Exciter-Voltage Regulator controls the generator output by varying the current applied to the generator field windings. Several inputs are supplied to the logic circuits, an appropriate field flashing current is calculated, and the output is then applied to the generator field windings.
DESCRIPTION OF EVENT:
D/G 2A was started at 0910 on March 2,1987, for a routine operability test (start No. 546, valid failure). It accelerated normally but did not reach 4160 VAC until 11.3 seconds had elapsed. Because all other indications were normal including the 8.5 seconds required to reach 95% speed, it was suspected that the Events Recorder which measures the D/G response time was in error. i I
The Events Recorder was evaluated and the indicated time for the D/G startup was determined to be correct. No discrepancy could be found in the Events Recorder time or with its operation; therefore, D/G 2A was declared inoperable 1
at 1013. The remaining essential power sources were verified as operable by 1050 in accordance with TS 3.8.1.1. A work request was written to investigate and correct the problem.
At 1514 on March 2, D/G 2A was started to begin troubleshooting. The time to reach 4160 VAC was 11.9 seconds but again, no other abnormalities were ob-served and no apparent cause was observed. Test recorders and other test instrumentation were installed and on March 3, D/G 2A was started twice. The times to reach 4160 VAC vcre 9.9 and 9.8 seconds respectively with no abnor-malities noted. After evaluating the test data, an intermittent malfunction in the Exciter-Voltage Regulator circuits was determined to be the probable cause and the circuit board containing those circuits was replaced. D/G 2A was started again for the Diesel Generator Voltage Regulator Benchmark Com-parison Test, which exercises the D/G through voltage and load transients and benchmarks the performance of the Exciter-Voltage Regulator. D/G 2A achieved 4160 VAC in 10.2 seconds, which is within its historical response time of 10.0
+/- 0.3 seconds.
The operability test was successfully run at 2055 on March 3, (start No. 551, Valid Success) and D/G 2A was declared operable at 2250. The subsequent two operability tests were both successful with the time to reach 4160 VAC at 10.0 seconds in both cases.
A subsequent examination and test on the Exciter-Voltage Regulator circuit bocrd found one failed capacitor in the output filter circuit. Two other capacitors also gave failure indications on the tester, but the tester could not be connected as required to do a confirming test without dismantlinF the circuit board. This was not done because the circuit board will be sent back to the vendor for a failure analysis and the circuit board must be intact for a thorough analysis. The failure of any of these capacitors causes an unpre-dictable response in the output signal controlling the generator field flash-ing currents.
CONCLUSION:
D/G 2A was inoperable from 1013 on March 2 to 2250 on March 3, a total of 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> and 37 minutes. The valid failure during start attempt number 546 was the sixth valid failure in the last one hundred valid starts on Unit 2 D/Gs.
The test frequency at the time of this failure was every three days and this frequency did not change as a result of this failure. During the time D/G 2A was inoperable, D/G 2B was started five times to verify the operability of the essential power sources in accordance with TS 3.8.1.1.
This incident has been attributed to the failure of the capacitor (Model number 210B1C106M) in the Exciter-Voltage Regulator (Basler Co. P/N 32101-102) output circuits. A failure of this capacitor can cause unpredictable results and in this incident it delayed the response time of the generator by under- i correcting the generator field currents. '
A review of past McGuire reports indicates there was one previous valid D/G start failure where diodes on the Exciter-Voltage Regulator circuit card had f ailed. Since the failed components are not the same as in this incident, even though they are on the Exciter-Voltage Regulator circuit board, this incident is considered non-recurring.
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This incident is Nuclear Plant Reliability Data System (NPRDS) reportable. A search of the NPRDS dats base did not reveal any other incidents of failed capacitors related to emergency diesel generator regulators. Failures of several other types of components 11 regulators were reported, but there were no indications of a trend with either the components or the regulators as a whole.
ADDITIONAL CORRECTIVE ACTIONS:
None SAFETY ANALYSIS:
The conditions for operation of the D/Gs are specified in the TSs and provide for degraded system conditions by placing appropriate restrictions on con-tinued operation of the unit commensurate with the level of degradation.
These TSs consider the Essential Power System as a whole, and the conditions are imposed on a system basis, i.e. combinations of D/Gs and offsite power sources constitute the minimum system requirements.
The operability of the power sources is consistent with the initial condition assumptions of the Final Safety Analysis Report (FSAR) safety analyses. At least one redundant set of onsite AC and DC power sources and akscciated distribution systems must be operable during accident conditions coincident with an assumed loss-of-offsite power and single failure of the other onsite AC source. The AC and DC source allowable out-of-service times are based on Regulatory Guide 1.93, " Availability of Electrical Power Sources", December 1974. When one D/G is inoperable there is an additional action requirement to verify that all required systems, subsystems, trains, components and devices that depend on the remaining operable D/G as a source of emergency power are also operable, and that the steam-driven auxiliary feedwater pump is operable.
This requirement is intended to provide assurance that a loss-of-offsite power event will not result in a complete loss of safety function of critical s systems during the period one of the D/Gs is inoperable. ;
During the period when D/G 2A was inoperable, the Train B systems were verified to be fully operable on a continuous basis along with both offsite power sources. If an accident had happened during the period of time D/G 2A was inoperable, those systems and components necessary to mitigate the accident were available and operable. D/G 2A was inoperable for approximately half of the time allowed by the TSs.
There were no personnel injuries, personnel overexposures, or releases of radioactive material as a result of this incident.
The health and safety of the public were not affected by this incident.
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