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Category:REPORTABLE OCCURRENCE REPORT (SEE ALSO AO LER)
MONTHYEARML20148T6101997-07-0303 July 1997 Follow-up to Special Rept SR-96-003-01:on 970411,damage to Cables for Sensors 1A & 1B Discovered.Sensor Cable for 7B Also Found Damaged.Cables for Channels 1A,1B & 7B Found Saturated W/Oil.Sensors Replaced for Channels 1A,1B & 7B ML20148N7281997-06-26026 June 1997 Special Rept SR-97-002-00:on 970513,personnel Identified Design Discrepancy for 'B' CCW Train Radiation Monitor. Design Flaw Existed Since Plant Built.Design Change DC-3537 Approved to Reroute Cooling Water Line from Connection ML20135E9641996-12-10010 December 1996 Special Rept SR-96-003-00:on 961027,valve & Loose Parts Monitoring Sys Declared Inoperable.Caused by Failure of Sensor on Channel 1.Sensor Will Be Replaced During Refueling Outage 8 ML20113E4501996-07-0303 July 1996 Special Rept SR-96-001-00:on 960603,output Breaker for EDG B Failed to Close.Caused by Intermittent Malfunction of Contacts on Synchronizing Switch.Performed Troubleshooting & Replaced EDG B Synchronizing Switch ML20094P5911995-11-27027 November 1995 Special Rept SR-95-004-00:on 951030,EDG Tripped on Turbocharger Low Lube Oil Pressure.Generated Condition Rept 95-1102 ML20094G2031995-11-0808 November 1995 Special Rept SR-95-003-00:on 951010,EDG Experienced Crankcase Overpressurization.Caused by Poor Lubricating Conditions During Startup & Rapid Loading Led to Tin Transfer from Piston to Cylinder Liner ML20093L8421995-10-23023 October 1995 Special Rept SR-95-002-00 on 951011,ABB C-E Identified Leaking Plug Due to build-up of Boric Acided Crystals Around OD of Plug.Leaking Plug Removed by Tig Relaxation & Replaced/Another Rolled Mechanical Plug ML20086E0181995-07-0707 July 1995 Special Rept SR-94-001-01:on 940228 & 0302,EDG a Experienced Nonvalid Failures Due to Worn Mechanical Governor Parts. Mechanical Governor & Faulty Relay Replaced & Procedure OP-009-02, EDG Revised ML20070N6601994-05-0404 May 1994 Special Rept SR-94-003:on 940404,EDG a Experienced Nonvalid Failure While Performing Valid Test.Probably Caused by Emergency Mode Master Run Relay 4EX1 de-energized During Run.Troubleshooting in Progress ML20065A3761994-03-29029 March 1994 Special Rept SR-94-001,on 940228,EDG a Tripped on Overspeed. Caused by Faulty Contacts in Relay of Electronic Grovernor Droop.Faulty Relay & Mechanical Governor Replaced ML20059B9521993-10-26026 October 1993 Special Rept SR-93-001-01,final Rept:On 930811,declared Condenser Vacuum Pump Wide Range Gas Monitor PRM-IRE-002 Inoperable.Monitor Returned to Svc on 930901.Inoperability of Subj Monitor Did Not Pose Safety Concern ML20056H1011993-09-0101 September 1993 Special Rept SR-93-001-00:on 930811,condenser Vacuum Pump WRGM PRM-IRE-002 Declared Inoperable & Not Returned to Svc within Seven Days.Monitor Will Be Returned to Svc After Low Range Sample Flow Cv Repaired & Functionally Checked ML20126M5881993-01-0606 January 1993 Special Rept SR-92-003:on 921207,EDG a Failed to Reach Rated Speed & Voltage in Less than or Equal to 10 S.Caused by Failure to Properly Secure Turning Gear Brackets.Control Brackets for Turning Gear Interlock Valves Adjusted ML20127M4981992-11-24024 November 1992 Special Rept SR-92-002-00:on 921023,component Cooling Water (CCW) A/B Radiation Monitor Was Inoperable for More than 30 Days.Ts Change Request NPF-38-127,dtd 921021 Submitted,Which Changes Operability Requirement ML20116B2121992-10-23023 October 1992 Special Rept SR-92-001-00:on 921010,inservice Eddy Current Exam of SG Tubing Completed,Per 10CFR50.36(c)(2).Total Number of Tubes Have Been Plugged in SG Shown as Listed ML20086K8731991-12-11011 December 1991 Special Rept SR-91-007-00:on 911111,diesel Generator a Loaded to 4.3 MW & Tripped.Caused by Inadequate Positioning of Turbocharger Inlet Air Butterfly Valve Limit Switch Mounting Bracket.Limit Switch Repositioned ML20086G0201991-11-27027 November 1991 Special Rept SR-91-002-02:on 910318,emergency Diesel Generator a Experienced Crankcase Overpressurization.Caused by Stuck Piston Rings.Piston & Piston Liner Replaced & Improper Temp Differential Will Be Corrected ML20083D4431991-09-23023 September 1991 Special Rept SR-91-002-01:on 910318,emergency Diesel Generator a Experienced Crankcase Overpressurization.Caused by Stuck Piston Rings & Improper Temp Differential.Cylinder Liner,Piston Assemblies & Rod Bearings Replaced ML20082U6231991-09-16016 September 1991 Special Rept SR-91-003-01:on 910406,inservice Eddy Current Exam of Facility SG Tubing Completed by Westinghouse.Rept Submitted Per Tech Specs 4.4.4.5 & 6.9.2.Rotating Pancake Coil Exam Results Verified No Detectable Degradation ML20082T2121991-09-13013 September 1991 Special Rept:On 910820,EDG Secured During Surveillance Test Due to Power Dropping Resistor Failure.Power Dropping Resistor Assembly Replaced.Health & Safety of Public & Plant Personnel Not Affected by This Event ML20082C4021991-07-15015 July 1991 Special Rept 91-005-00:on 910619,EDG a Tripped on Turbocharger Lube Oil Low Pressure During Performance of Operating Procedure 903-068.Procedure Changed to Require Lubrication of Turbocharger ML20073Q8001991-05-29029 May 1991 Special Rept SR-91-04-00:on 910429,EDG a Failed Invalidly Due to Spurious Turbocharger Lube Oil Pressure Trip.Edg Restarted.Oil Pressure Remained within Normal Operating Limits & OP-903-068 Completed ML20073B3231991-04-19019 April 1991 Special Rept SR-91-003-00,re 910406 Completion of Inservice Eddy Current Exam of Steam Generator tubing.Follow-up Rept Will Be Submitted by 920406,per Tech Spec 4.4.4.5.b.Total Number of Tubes Plugged in Each Steam Generator Listed ML20084U8591991-04-17017 April 1991 Special Rept SR-91-002-00:on 910318,emergency Diesel Generator a Experienced Crankcase Overpressurization. Possibly Caused by Improper Temp Differential Between Jacket Cooling Water & Lube Oil Temp.Liner Replaced ML20072Q8931991-03-18018 March 1991 Special Rept SR-91-001-00:on 910207,channel 2 of SPDS Failed & Could Not Be Restored within 7 Days.On 910214, Channel 2 of Qualified SPDS Sensor 8 Out of Svc for More than 7 Days.Channel 2 Probe Will Be Replaced ML20065R6021990-12-12012 December 1990 Special Rept SR-90-003-00:on 901112,invalid Failure of Emergency Diesel Generator a Occurred.Caused by Mechanical Failure of 30 Psig Reducer in Control Air Sys & Crack on Spring Cap of Reducer.All Reducers Inspected ML20246C9091989-05-0303 May 1989 Special Rept SR-89-001-01:on 890206 & 0403,emergency Diesel Generator a Declared Inoperable.Caused by Fuse Not Being Secured in Fuse Holder & Oxidation of Speed Control Circuit Relay Contacts.Contacts Cleaned & Fuses & Holders Checked ML20245A3951989-04-10010 April 1989 Special Rept SR-88-004-01:on 880420,inservice Eddy Current Exam of Steam Generator Tubing Completed by Westinghouse.Two Tubes Exceeded Plugging Limit in Steam Generator A.All Discrepancies Resolved ML20236B0941989-03-0808 March 1989 Special Rept:On 890206,emergency Diesel Generator Secured Due to Failure of Speed Control Circuit While Generator in Manual Operation.Caused by Oxidation of Relay Contacts in Governor Control Circuitry.Contacts Replaced ML20206H4901988-11-18018 November 1988 Special Rept SR-88-009-00:on 880909,emergency Diesel Generator Tripped Due to Incorrect Valve Lineup.Caused by Personnel Error.Valves Opened ML20151U8841988-08-16016 August 1988 Special Rept SR-88-008-00:on 880726,plant Stack Effluent Accident wide-range Gas Monitor Declared Inoperable.Caused by Pump Failing Step 8.4.2.18 Which Checks high-range Sample Flow within Specified Tolerance.Transmitter Replaced ML20151C1121988-07-15015 July 1988 Special Rept SR-88-007-00:on 880628,primary Meteorological Tower Instruments out-of-svc Greater than Seven Days.Caused by Instruments Being Out of Calibr.Temp Elements Replaced & Corrective Maint on Delta Temp Instruments Completed ML20151C0781988-07-15015 July 1988 Special Rept SR-88-006-00:on 880616,emergency Diesel Generator B Tripped Due to Personnel Error.Caused by Failure to Raise Load within 5 S.Operating Procedure OP-9-002 Reviewed & Considered to Adequately Address Operation ML20195H7171988-06-20020 June 1988 Special Rept SR-88-005-00:on 880511,unit Was in Refueling Mode When Operations Personnel Declared Seismic Monitor SM-IYR-6021 Inoperable.Plastic Lexan Mounting Board Appeared to Be Deformed Due to Heat.Monitor Will Be Relocated ML20153F3831988-05-0404 May 1988 Special Rept SR-88-003-01:on 850801-880404 Several Failures of Emergency Diesel Generators to Start Occurred.Caused by Actuation of Trips Which Bypassed in Emergency Mode.Trip Sensor Replaced ML20153F2541988-05-0404 May 1988 Special Rept SR-88-004-00:on 880420,inservice Eddy Current Exam of Steam Generator Tubing Completed.Rept Submitted in Accordance W/Tech Specs 4.4.4.5.a.Number of Tubes Plugged in Each Steam Generator Listed ML20148F1021988-03-21021 March 1988 Special Rept SR-85-002-01:on 851230,discovered Emergency Diesel Generator a Failed to Complete Surveillance Run as Defined in Procedure OP-903-068 & Tech Spec 4.8.1.1.2a.5. Cause Not Determined.Minor Adjustments Made to Governor ML20148F0971988-03-18018 March 1988 Special Rept SR-88-003-00:from 850801-880308,several Emergency Diesel Generators Failed to Start.Caused by Malfunctioning Trip Mechanisms.Diesels Will Not Be Taken Out of Svc Until Plant Scheduled to Be out-of-svc for Maint ML20149J3411988-02-18018 February 1988 Special Rept SR-88-001-00:on 880128,during Plant Startup Operations,Personnel Declared Fuel Handling Exhaust Wide Range Gas Monitor out-of-svc for Calibr.Caused by Extensive Teardown.Procedure Revised ML20236Q1121987-11-16016 November 1987 Special Rept SR-87-006-00:on 871028,primary Meteorological Tower Upper Wind Speed & Wind Direction Instrument out-of- Svc in Excess of 7 Days.Caused by Failed Signal Converter. Parts Replaced & Instrument Returned to Svc on 871104 ML20236Q2621987-11-13013 November 1987 Special Rept SR-87-005-00:on 871103,Tech Specs 3.3.3.1 & 6.9.2 Violated.Caused by Inoperability of Effluent Accident wide-range Gas Monitor for More than 7 Days Due to Damaged Connectors.New Monitor Should Be Installed by 871125 ML20235J8531987-09-24024 September 1987 Special Rept SR-87-004-00 Re Results of Inservice Eddy Current Exam of Steam Generator Tubing Completed on 861214. No Indication of Degradation Greater than or Equal to 20% Through Wall Detected in Steam Generator a ML20237G9341987-08-21021 August 1987 Special Rept SR-87-003-00:on 870731 & 0809,condenser Vacuum Vacuum Pump Discharge Wide Range Gas Monitor (WRGM) Inoperable.Caused by Water Blockage of Sample Lines.Wrgm Restarted & Being Tested for Operation ML20234B2111987-06-29029 June 1987 Special Rept SR-87-002-00:on 870606,high Range Gas Monitor Inoperable Greater than 7 Days.Caused by Faulty Display Module & Lack of Spares & Quality Documentation.Module Replaced & Monitor Returned to Svc After Functional Test ML20215H0841987-06-17017 June 1987 Special Rept SR-87-001-00:on 870527,during Full Reactor Power,Condenser Vacuum Pump Discharge Wide Range Gas Monitor Declared Inoperable.Caused by Failed Input/Output Circuit Board & Low Range Detector.Faulty Components Replaced ML20205G1731987-03-18018 March 1987 Ro:On 870222,steam Line Break on Scavenging Steam Vent Line from Moisture Separator Reheater Experienced.Caused by Classic Fatigue Failure in Heat Affected Zone of Weld Joining Alloy 800 Matl.Temporary Restraints Added W3P87-0237, Suppl 1 to Special Rept SR-85-001:on 850916,seismic Monitor Mounted on Pressurizer Found Damaged & Inoperable.Relocation of Seismic Monitor Completed,But Tech Spec Not Yet Approved1987-01-19019 January 1987 Suppl 1 to Special Rept SR-85-001:on 850916,seismic Monitor Mounted on Pressurizer Found Damaged & Inoperable.Relocation of Seismic Monitor Completed,But Tech Spec Not Yet Approved ML20214V2821986-09-26026 September 1986 Special Rept SR-86-005-00:on 860909 & 17,secondary & Primary Towers Removed from Svc,Respectively,But Not Returned to Svc within 7 Days.Caused by Need to Replace Hoist Cables. Secondary Tower Returned to Svc on 860916 ML20206J6331986-06-20020 June 1986 Special Rept SR-86-004-00:on 860523,emergency Diesel Generator a Malfunctioned.Caused by Failure of Power Parallel Voltage Dropping Resistor in Electrical Governor Control Circuit.Power Resistors & Amplifier Replaced ML20211H3531986-06-13013 June 1986 Special Rept SR-86-003-00:on 860523,wide-range Gas Monitor PRM-JR-0110 Declared Inoperable.Caused by Performance of Functional Test Per Procedure MI-3-382.Check Valve Removed & Seat Reworked.Monitor Returned to Svc on 860604 1997-07-03
[Table view] Category:TEXT-SAFETY REPORT
MONTHYEARML20217F2891999-10-13013 October 1999 Drill 99-08 Emergency Preparedness Exercise on 991013 ML20217G7211999-09-30030 September 1999 Monthly Operating Repts for Sept 1999 for Waterford 3 Ses. with ML20211Q2141999-08-31031 August 1999 Monthly Operating Rept for Aug 1999 for Waterord 3 Ses.With ML20210Q6361999-07-31031 July 1999 Corrected Monthly Operating Rept for July 1999 for Waterford 3 ML20210S0581999-07-31031 July 1999 Monthly Operating Rept for July 1999 for Waterford 3.With ML20210D8951999-07-23023 July 1999 Safety Evaluation Accepting First 10-yr Interval Inservice Insp Plan Requests for Relief ISI-018 - ISI-020 ML20209H3781999-06-30030 June 1999 Monthly Operating Rept for June 1999 for Waterford 3 Ses. with ML20195J8951999-06-17017 June 1999 Safety Evaluation Granting Relief for Listed ISI Parts for Current Interval,Per 10CFR50.55a(g)(5)(iii) ML20207E8631999-06-0303 June 1999 Safety Evaluation Accepting Licensee 990114 Submittal of one-time Request for Relief from ASME B&PV Code IST Requirements for Pressure Safety Valves at Plant,Unit 3 ML20195K3391999-05-31031 May 1999 Monthly Operating Rept for May 1999 for Waterford 3 Ses.With ML20195C3041999-05-28028 May 1999 Annual Rept on Abb CE ECCS Performance Evaluation Models ML20206S7401999-04-30030 April 1999 Monthly Operating Rept for Apr 1999 for Waterford 3.With ML20205T2621999-04-22022 April 1999 LER 99-S02-00:on 990216,contract Employee Inappropriately Granted Unescorted Access to Plant Protected Area.Caused by Personnel Error.Security Personnel Performed Review of Work & Work Area That Individual Was Involved with ML20205N9671999-03-31031 March 1999 Monthly Operating Rept for Mar 1999 for Waterford 3 Ses.With ML20205E8531999-03-30030 March 1999 Corrected Pages COLR 3/4 1-4 & COLR 3/4 2-6 to Rev 1, Cycle 10, Colr ML20205A6331999-03-25025 March 1999 SER Accepting Request to Use Mechanical Nozzle Seal Assemblies as an Alternative Repair Method,Per 10CFR50.55a(a)(3)(i) for Reactor Coolant Sys Applications at Plant,Unit 3 ML20204H1401999-03-23023 March 1999 Rev 1 to Engineering Rept C-NOME-ER-0120, Design Evaluation of Various Applications at Waterford Unit 3 ML20204H1231999-03-22022 March 1999 Rev 1 to Design Rept C-PENG-DR-006, Addendum to Cenc Rept 1444 Analytical Rept for Waterford Unit 3 Piping ML20204H2451999-03-22022 March 1999 Rev 2 to C-NOME-SP-0067, Design Specification for Mechanical Nozzle Seal Assembly (Mnsa) Waterford Unit 3 ML20204F0791999-03-17017 March 1999 Rev 1 to Waterford 3 COLR for Cycle 10 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 ML20207F3491999-03-0505 March 1999 LER 99-S01-00:on 990203,contraband Was Discovered in Plant Protected Area.Bottle Was Determined to Have Been There Since Original Plant Construction.Bottle Was Removed & Security Personnel Performed Search of Area.With ML20204B5141999-02-28028 February 1999 Monthly Operating Rept for Feb 1999 for Waterford 3.With ML20203H8591999-02-17017 February 1999 Safety Evaluation Accepting Licensee Second Ten Year ISI Program & Associated Relief Requests for Plant,Unit 3 ML20199H6261999-01-21021 January 1999 Safety Evaluation Accepting Classification of Instrument Air Tubing & Components for Safety Related Valve Top Works.Staff Recommends That EOI Revise Licensing Basis to Permit Incorporation of Change ML20199C9101998-12-31031 December 1998 Monthly Operating Rept for Dec 1998 for Waterford 3.With ML20196F4911998-12-0101 December 1998 SER Accepting Request for Relief ISI2-09 for Waterford Steam Electric Station,Unit 3 & Arkansas Nuclear One,Unit 2 ML20206N4131998-11-30030 November 1998 Monthly Operating Rept for Nov 1998 for Waterford 3.With ML20195C4841998-11-0606 November 1998 SER Accepting QA Program Change to Consolidate Four Existing QA Programs for Arkansas Nuclear One,Grand Gulf Nuclear Station,River Bend Station & Waterford 3 Steam Electric Station Into Single QA Program ML20195E5161998-10-31031 October 1998 Monthly Operating Rept for Oct 1998 for Waterford 3.With ML20155C1351998-10-26026 October 1998 Rev B to Entergy QA Program Manual ML20154K0801998-09-30030 September 1998 Monthly Operating Rept for Sept 1998 for Waterford 3 Ses. with ML20151W8331998-08-31031 August 1998 Monthly Operating Rept for Aug 1998 for Waterford,Unit 3. with ML20237B6831998-08-17017 August 1998 LER 98-S01-00:on 980723,discovered That Waterford 3 Physical Security Plan,Safeguards Document Was Not Under Positive Control of Authorized Person at All Times.Caused by Human Error/Inappropriate Action.Counseled Employee Involved ML20237C5661998-08-17017 August 1998 Safety Evaluation Accepting Licensee Request for Exemption from Section Iii.O of Appendix R to 10CFR50 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 ML20237B5261998-07-31031 July 1998 Monthly Operating Rept for July 1998 for Waterford 3 ML20236S9031998-07-22022 July 1998 SER Accepting Rev 19 to Quality Assurance Program for Waterford Steam Electric Station,Unit 3 ML20198H3911998-07-14014 July 1998 Non-proprietary Rev 5 to HI-961586, Thermal-Hydraulic Analysis of Waterford-3 Spent Fuel Pool ML20236N4181998-06-30030 June 1998 Monthly Operating Rept for June 1998 for Waterford,Unit 3 ML20248E7781998-06-0101 June 1998 Annual Rept on Abb CE ECCS Performance Evaluation Models ML20249A4711998-05-31031 May 1998 Monthly Operating Rept for May 1998 for Waterford 3 Ses ML20196A4051998-05-31031 May 1998 Rept of Facility Changes,Tests & Experiments,Per 10CFR50.59 for 970601-980531. with ML20198H4681998-05-20020 May 1998 Non-proprietary Rev 1 to HI-981942, Independent Review of Waterford Unit 3 Spent Fuel Pool Cfd Model ML20247A3891998-05-0101 May 1998 SG Eddy Current Examination (8th Refueling Outage) ML20247F6761998-04-30030 April 1998 Monthly Operating Rept for Apr 1998 for Waterford,Unit 3.W/ ML20217M8951998-04-30030 April 1998 QA Program Manual ML20217P8281998-04-0707 April 1998 Safety Evaluation Accepting Relief Authorization for Alternative to Requirements of ASME Section Xi,Subarticle IWA-5250 Bolting Exam for Plants,Per 10CFR50.55a(a)(3)(i) ML20216B1751998-03-31031 March 1998 Monthly Operating Rept for Mar 1998 for Waterford 3 Ses ML20217M1411998-03-0303 March 1998 Rev 2 of Waterford 3 Cycle 9 Colr 1999-09-30
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, Mg Entergy Operations, Inc.
O 6 Ki ona LA 70006 Tel 504-464-3120 D. R. Keuter General Manager Plant Operations a Waterford 3 W3F1-95-0056 A4.05 7
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July 7,1995 U.S. Nuclear Regulatory Commission I
Attn: Document Control Desk Washington, D.C. 20555
Subject:
Waterford 3 SES Docket No. 50-382 License No. NPF-38 Reporting of Special Report b
Attached is Special Report Number SR-94-001-01 for Waterford P- i Electric Station Unit 3. This revision outlines the results the investigation into the overspeed and reverse power trips of Emergency Diesel Generator "A" previously reported in revision 0 of this report.
The overspeed trip was most probably caused by worn governor parts and the reverse power trip was most probably caused by an intermittent problem f with the synchronizing switch. This Special Report is submitted in i j ai II!
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c Reporting of Special Report k3F1-95-0056 Page 2 July 7,1995 accordance with Technical Specifications 4.8.1.1.3 and 6.9.2 and USNRC Regulatory Guide 1.108.
I Very truly yours,
-$4 D.R. Keuter General Manager - Plant Operations DRK/RTK/tjs Attachment cc: L.J. Callan, NRC Region IV C.P. Patel, NRC-NRR G.L. Florreich J.T. Wheelock - INP0 Records Center R.B. McGehee N.S. Reynolds Administrator - LRPD NRC Resident Inspectors Office (WMSB4300)
.- SPECIAL REPORT SR-94-001-01 REPORTABLE OCCURRENCE Emergency Diesel Generator (EDG) 'A' experienced nonvalid failures on two occasions. The first failure occurred during a nonvalid test on February 28, 1994; the second during a valid test on March 2, 1994. An additional 1 invalid failure occurred during the troubleshooting process.
EVENT DESCRIPTION At 1318 on February 28, 1994, Emergency Diesel Generator (EDG) ' A' was started in accordance with Operating Procedure OP-903-068, " Emergency Diesel Generator and Subgroup Relay Operability Verification", to demonstrate the operability of the diesel in accordance with Technical Specification (TS) 4.8.1.1.2. Approximately 37 minutes after reaching full load, EDG load began to oscillate between 3.8 and 4.4 MW. The EDG was subsequently unloaded, secured, and declared inoperable at 1424 At 1605 on February 28th, operators attempted to start EDG 'A' using the mechanical governor (electronic governor disconnected) as a first step in localizing the problem. This start was unsuccessful as the EDG tripped on overspeed. A new mechanical governor was installed and tested satisfactorily. However, with the electronic governor back in service, the load oscillations were still present, indicating that any remaining fault was in the electronic and not the mechanical governor.
Subsequent troubleshooting identified faulty relay contacts associated l with the electronic governor's ' droop' (test) mode of operation. After replacing the relay, EDG ' A' was started at 1237 on March 2,1994, to verify correction of the problem and demonstrate compliance with TS 4.8.1.1.2. In the process of paralleling to the bus, the EDG tripped on reverse power.
At 1439 on March 2, 1994, EDG 'A' was restarted to perform the TS surveillance. The test was completed satisfactorily and the diesel was declared operable at 1740.
C_A_USAL FACTORS Investigation to date revealed that the load oscillations were caused by the failure of a ' set of relay contacts associated with the electronic l governor's ' droop' mode of operation. These contacts are utilized when the EDG is paralleled to the bus for loading after an emergency mode start. They are not used during emergency ('isochronous') operation and thus would not have prevented the EDG from performing its safety function.
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$e mechanical governor was sent to the vendor (Cooper Bessemer) for analysis. Based on the Failure Analysis Report provided by Cooper Bessemer, it was concluded that the most probable root cause of the engine overspeed trip was worn mechanical governor parts. The wear detected was very slight. However, the sequence of events (electrical governor disconnected) which produced the overspeed trip, represents an extreme test of the capabilities of the mechanical governor actuator. Under these
- circumstances, the actuator must move the fuel rack from fully open to fully closed after the speed passes the hydraulic speed setting of the actuator (608 engine rpm) but before it reaches the overspeed setting (660 rpm). Based on original factory test data, this must be accomplished in 0.4 seconds or less.
l An investigation has revealed that the most probable cause of the reverse power trip is an intermittent problem with the synchronizing switch.
During the performance of OP-903-068, the EDG is initially started in the emergency mode of operation and later transfers to the test mode of operation when the EDG is synchronized to offsite power. The synchronizing switch is utilized to enable EDG manual speed contrcl when the EDG is being synchronized to offsite power. If the contact blocks on this switch fail to make good electrical connections, manual speed control may not be enabled. Operations personnel may not be aware that EDG speed and frequency indications are not being supplied by the manual speed control circuitry but instead are continuing to be supplied by the emergency mode circuitry. However, the motor operated potentiometer that is used to adjust the EDG reference speed signal in the test mode can still be manipulated. If this motor operated potentiometer is left in a position that would provide a speed reference signal to the EDG that is too slow, motoring of the generator can occur when the EDG output circuit breaker is closed. This would occur because relays in the EDG speed control circuitry would cause the EDG to exit the emergency mode of operation and return to the test mode of operation which would have the effect of immediately enabling the manual speed control circuitry. The result would be an immediate reverse power trip of the EDG.
CORRECTIVE MEASURES I The mechanical owernor and faulty relay were replaced.
Procedure OP-009-002 " Emergency Diesel Generator" has been revised to require Operations personnel to verify that speed control has been enabled prior to synchronizing the EDGs to offsite power. Replacement of the contact blocks on the synchronizing switch will require lifting "H0T" leads in a highly congested area. This activity is currently scheduled to i
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I he. completed during the Refuel 7 Outage. As an interim corrective ineasure, a Caution Tag has been placed on this switch to alert Operations Personnel as to the condition of this switch.
SAFETY SIGNIFICAtLCI An engineering evaluation of EDG governor circuitry determined that the faulty relay contacts would not have affected EDG operation in the emergency mode. Similarly, the reverse power trip events would not have affected emergency mode operation because this trip is bypassed during emergency mode operation. The mechanical governor controls diesel speed during starting and functions as a backup to the electrical governor to prevent an overspeed situation if the electrical governor should fail to maximum output. The overspeed trip was caused by having the electrical governor disconnected during the troubleshooting process and slightly worn governor parts. During an emergency mode start due to degraded voltage or a loss of voltage on the 4160 volt safety bus, the demand on the mechanical governor actuator is less severe since the automatic breaker closure and load sequencing will apply immediate load to the engine. In this situation, the governor does not have to close the fuel racks for several seconds after the diesel has reached operating speed. Therefore, in the emergency mode, with the electrical governor connected, this trip would not have occurred. In addition, EDG 'B' was operable. Safety analysis assumes that a single failure disables one protection train.
However, a single EDG, safety bus, and associated Engineered Safety Features equipment is adequate to protect the reactor during the worst case postulated accident. As a result, these events did not compromise .
the health and safety of the public or plant personnel. l In accordance with USNRC Regulatory Guide 1.108, the current surveillance test interval for EDG 'A' is 31 days. EDG 'A' was unavailable for 51.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />.
SIMILAR EVENTS A similar event involving a reverse power trip is described in Special Report Number SR-94-003-00. The information available to date indicates that the synchronizing switch contact blocks were also responsible for that trip.
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