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Category:REPORTABLE OCCURRENCE REPORT (SEE ALSO AO
MONTHYEARML20029C6191994-04-14014 April 1994 Special Rept:On 940328,meteorological Tower Instrumentation Not Returned to Svc within Allowed Out of Svc Time.Caused by Difficulty in Calibr of Input Card.Meteorological Monitoring Instrumentation Declared Operable on 940408 ML20046A0321993-07-19019 July 1993 Special Rept:On 930704,TS Time Limit Expired for SGTS Exhaust Stack High Range Radioactivity Monitor Declared Inoperable on 930701 Due to Low Sample Flow Reading. Suspected Degraded Pump Replaced.Followup Will Be Provided ML20029B1901991-02-27027 February 1991 Rev to RO Dtd 910205 Re Valid Failure of Div II Diesel Generator During Surveillance Testing on 910106.Caused by Failure of A-3 Relay Tachometer Due to Broken Wire.Caution Added to Vendor Manual Re Bench Testing Relay ML20043D1631990-05-30030 May 1990 Supplemental Special Rept on Test Failures of Div I Diesel Generator at Plant on 891220 & 900111.Problem Caused by Misapplication of Woodward EGB13P Model 9903-266 Governor. Mods Not Warranted.Diesel Generator Being Tested Weekly ML20043B3021990-05-21021 May 1990 Special Rept:On 900502,during Performance of Semiannual Channel Calibr,Personnel Identified That 60-meter Wind Direction Instrumentation Not in Calibr.Instrumentation Declared Operable on 900510 After Procedure Completed ML20043A9821990-05-15015 May 1990 Ro:On 900508,discovered That Replacement Bellows Had Tie Rods Installed to Limit Bellows Expansion.Div I & II Diesel Generators Declared Inoperable & Controlled Plant Shutdown Initiated.Unusual Event Terminated on 900509 ML20012F0591990-03-29029 March 1990 Special Rept:On 891120-1230,valid Test Failures of Div I Diesel Generator.Current Valid Failure Count for Diesel Generator Is Three.Diesel Generator Continues to Be Tested on Weekly Basis Per Tech Spec Table 4.8.1.1.2.1 ML20006F6351990-02-20020 February 1990 Ro:On 900212,Tech Specs 3.6.1.8 & 3.6.1.1 Entered Due to Failed Local Leak Rate Test on Primary Containment Penetration MC-102.Plant Shutdown Commenced & Notification of Unsual Event Declared.Plant Placed in Shutdown Condition ML20006D1541990-01-29029 January 1990 Special Rept:On 891230,during Test to Restore Diesel Generator 1A to Operable Status Following Failure on 891227, Generator Cranked But Did Not Start.Caused by Failure of Contacts on K19 Control set-up Relay.Relay Replaced ML20005G3371990-01-11011 January 1990 Special Rept:On 891211,failure of Diesel Generator DG1A to Start Noted.Caused by Failure of K19 Starting Relay.Diesel Generator Governor & Defective Speed Sensing Relay Replaced ML20005F8111990-01-0404 January 1990 Special Rept:On 891219,differential Air Temp Instrumentation Inoperable for More than 7 Days.Caused by Problem in Temp Probe on Meteorological Tower.Tower Differential Temp Instrumentation Declared Operable on 891229 ML20005E0811989-12-20020 December 1989 Special Rept:On 891120,Div 1 Diesel Generator 1A Failed During Surveillance Testing.Caused by Erratic Start Times. Diesel Generator Governors Readjusted ML19332E6121989-11-29029 November 1989 Special Rept:On 891030,test Failure of Div II Diesel Generator Occurred.Caused by Cam/Spring Holding Fallen Screw in Console Section of Panel.Holding Screw Reinstalled in Switch.Control Switch Will Be Inspected in Upcoming Outage 1994-04-14
[Table view] Category:LER)
MONTHYEARML20029C6191994-04-14014 April 1994 Special Rept:On 940328,meteorological Tower Instrumentation Not Returned to Svc within Allowed Out of Svc Time.Caused by Difficulty in Calibr of Input Card.Meteorological Monitoring Instrumentation Declared Operable on 940408 ML20046A0321993-07-19019 July 1993 Special Rept:On 930704,TS Time Limit Expired for SGTS Exhaust Stack High Range Radioactivity Monitor Declared Inoperable on 930701 Due to Low Sample Flow Reading. Suspected Degraded Pump Replaced.Followup Will Be Provided ML20029B1901991-02-27027 February 1991 Rev to RO Dtd 910205 Re Valid Failure of Div II Diesel Generator During Surveillance Testing on 910106.Caused by Failure of A-3 Relay Tachometer Due to Broken Wire.Caution Added to Vendor Manual Re Bench Testing Relay ML20043D1631990-05-30030 May 1990 Supplemental Special Rept on Test Failures of Div I Diesel Generator at Plant on 891220 & 900111.Problem Caused by Misapplication of Woodward EGB13P Model 9903-266 Governor. Mods Not Warranted.Diesel Generator Being Tested Weekly ML20043B3021990-05-21021 May 1990 Special Rept:On 900502,during Performance of Semiannual Channel Calibr,Personnel Identified That 60-meter Wind Direction Instrumentation Not in Calibr.Instrumentation Declared Operable on 900510 After Procedure Completed ML20043A9821990-05-15015 May 1990 Ro:On 900508,discovered That Replacement Bellows Had Tie Rods Installed to Limit Bellows Expansion.Div I & II Diesel Generators Declared Inoperable & Controlled Plant Shutdown Initiated.Unusual Event Terminated on 900509 ML20012F0591990-03-29029 March 1990 Special Rept:On 891120-1230,valid Test Failures of Div I Diesel Generator.Current Valid Failure Count for Diesel Generator Is Three.Diesel Generator Continues to Be Tested on Weekly Basis Per Tech Spec Table 4.8.1.1.2.1 ML20006F6351990-02-20020 February 1990 Ro:On 900212,Tech Specs 3.6.1.8 & 3.6.1.1 Entered Due to Failed Local Leak Rate Test on Primary Containment Penetration MC-102.Plant Shutdown Commenced & Notification of Unsual Event Declared.Plant Placed in Shutdown Condition ML20006D1541990-01-29029 January 1990 Special Rept:On 891230,during Test to Restore Diesel Generator 1A to Operable Status Following Failure on 891227, Generator Cranked But Did Not Start.Caused by Failure of Contacts on K19 Control set-up Relay.Relay Replaced ML20005G3371990-01-11011 January 1990 Special Rept:On 891211,failure of Diesel Generator DG1A to Start Noted.Caused by Failure of K19 Starting Relay.Diesel Generator Governor & Defective Speed Sensing Relay Replaced ML20005F8111990-01-0404 January 1990 Special Rept:On 891219,differential Air Temp Instrumentation Inoperable for More than 7 Days.Caused by Problem in Temp Probe on Meteorological Tower.Tower Differential Temp Instrumentation Declared Operable on 891229 ML20005E0811989-12-20020 December 1989 Special Rept:On 891120,Div 1 Diesel Generator 1A Failed During Surveillance Testing.Caused by Erratic Start Times. Diesel Generator Governors Readjusted ML19332E6121989-11-29029 November 1989 Special Rept:On 891030,test Failure of Div II Diesel Generator Occurred.Caused by Cam/Spring Holding Fallen Screw in Console Section of Panel.Holding Screw Reinstalled in Switch.Control Switch Will Be Inspected in Upcoming Outage 1994-04-14
[Table view] Category:TEXT-SAFETY REPORT
MONTHYEARU-603277, Monthly Operating Rept for Sept 1999 for Clinton Power Station,Unit 1.With1999-09-30030 September 1999 Monthly Operating Rept for Sept 1999 for Clinton Power Station,Unit 1.With ML20217A1691999-09-22022 September 1999 Part 21 Rept Re Engine Sys,Inc Controllers,Manufactured Between Dec 1997 & May 1999,that May Have Questionable Soldering Workmanship.Caused by Inadequate Personnel Training.Sent Rept to All Nuclear Customers U-603267, Monthly Operating Rept for Aug 1999 for Clinton Power Station,Unit 1.With1999-08-31031 August 1999 Monthly Operating Rept for Aug 1999 for Clinton Power Station,Unit 1.With U-603245, Monthly Operating Rept for Jul 1999 for CPS Unit 1.With1999-07-31031 July 1999 Monthly Operating Rept for Jul 1999 for CPS Unit 1.With ML20211C9621999-07-26026 July 1999 ISI Summary Rept U-603232, Special Rept:On 990531 Lpms Was Declared Inoperable Due to Receipt of High Vibration & Loose Parts Alarm Which Did Not Clear.Lpms Was Restored to Operable Status on 990707 After Alignment & Tension on Recorder Tape Drive Was Adjusted1999-07-0909 July 1999 Special Rept:On 990531 Lpms Was Declared Inoperable Due to Receipt of High Vibration & Loose Parts Alarm Which Did Not Clear.Lpms Was Restored to Operable Status on 990707 After Alignment & Tension on Recorder Tape Drive Was Adjusted U-603233, Monthly Operating Rept for June 1999 for Clinton Power Station,Unit 1.With1999-06-30030 June 1999 Monthly Operating Rept for June 1999 for Clinton Power Station,Unit 1.With U-603222, Monthly Operating Rept for May 1999 for Clinton Power Station.With1999-05-31031 May 1999 Monthly Operating Rept for May 1999 for Clinton Power Station.With ML20210K8391999-05-11011 May 1999 British Energy Annual Rept & Accounts 1998-99 ML20206H1231999-05-0505 May 1999 Illinois Power Co CPS Main CR Simulator Certification Rept U-603210, Monthly Operating Rept for Apr 1999 for Cps,Unit 1.With1999-04-30030 April 1999 Monthly Operating Rept for Apr 1999 for Cps,Unit 1.With U-603204, Final Part 21 Rept 21-99-003 Re Deficiency in Commercial Grade Dedication Process Used by Circuit Breaker Refurbishment Supplier Trentec for Westinghouse Breaker 1AP05EH.Issue Determined Not Reportable Per 10CFR211999-04-30030 April 1999 Final Part 21 Rept 21-99-003 Re Deficiency in Commercial Grade Dedication Process Used by Circuit Breaker Refurbishment Supplier Trentec for Westinghouse Breaker 1AP05EH.Issue Determined Not Reportable Per 10CFR21 U-603192, Monthly Operating Rept for Mar 1999 for Clinton Power Station,Unit 1.With1999-03-31031 March 1999 Monthly Operating Rept for Mar 1999 for Clinton Power Station,Unit 1.With U-603182, Part 21 Rept Re Deficiency in Commercial Grade Dedication Process Used by Circuit Breaker Refurbishment Supplier, Trentec.Condition Rept 1-99-01-136 Was Initiated to Track Investigation & Resolution of Issue1999-03-12012 March 1999 Part 21 Rept Re Deficiency in Commercial Grade Dedication Process Used by Circuit Breaker Refurbishment Supplier, Trentec.Condition Rept 1-99-01-136 Was Initiated to Track Investigation & Resolution of Issue U-603176, Monthly Operating Rept for Feb 1999 for Clinton Power Station,Unit 1.With1999-02-28028 February 1999 Monthly Operating Rept for Feb 1999 for Clinton Power Station,Unit 1.With ML20207F2031999-02-10010 February 1999 Rev 1 to CPS COLR for Reload 6 Cycle 7 ML20202J0181999-02-0303 February 1999 SER Accepting Changes in Quality Assurance Program,Which Continues to Meet Requirements of App B to 10CFR50 U-603144, Monthly Operating Rept for Dec 1998 for Clinton Power Station,Unit 1.With1998-12-31031 December 1998 Monthly Operating Rept for Dec 1998 for Clinton Power Station,Unit 1.With U-603223, Illinova Corp 1998 Annual Rept. with1998-12-31031 December 1998 Illinova Corp 1998 Annual Rept. with U-603115, Part 21 Interim Rept 21-98-021 Re Deficiencies in Matl Dedication Process Used by Goulds Pumps in Supplying SR Parts to Npps.Issue Is Not Reportable Under 10CFR21. Dedication Process Did Not Affect Ability of Components1998-12-0404 December 1998 Part 21 Interim Rept 21-98-021 Re Deficiencies in Matl Dedication Process Used by Goulds Pumps in Supplying SR Parts to Npps.Issue Is Not Reportable Under 10CFR21. Dedication Process Did Not Affect Ability of Components U-603124, Monthly Operating Rept for Nov 1998 for Clinton Power Station,Unit 1.With1998-11-30030 November 1998 Monthly Operating Rept for Nov 1998 for Clinton Power Station,Unit 1.With U-603114, Part 21 Rept 21-98-049 Re W Dhp Circuit Breaker Refurbished by Nuclear Logistics,Inc Which Failed to Operate.Caused by Trip Latch out-of-adjustment & Incorrectly Sized Ratchet Lever Assembly Bushing.Breakers Were Returned to Vendor1998-11-25025 November 1998 Part 21 Rept 21-98-049 Re W Dhp Circuit Breaker Refurbished by Nuclear Logistics,Inc Which Failed to Operate.Caused by Trip Latch out-of-adjustment & Incorrectly Sized Ratchet Lever Assembly Bushing.Breakers Were Returned to Vendor U-603103, Monthly Operating Rept for Oct 1998 for Clinton Power Station,Unit 1.With1998-10-31031 October 1998 Monthly Operating Rept for Oct 1998 for Clinton Power Station,Unit 1.With U-603101, Special Rept:On 980918,discovered That Triaxial Seismic Accelerometers Had Not Been Properly Calibrated.Caused by Inadequate Calibration Procedure.Calibration to Be Performed off-site1998-10-28028 October 1998 Special Rept:On 980918,discovered That Triaxial Seismic Accelerometers Had Not Been Properly Calibrated.Caused by Inadequate Calibration Procedure.Calibration to Be Performed off-site ML20154F8701998-10-0606 October 1998 Safety Evaluation Authorizing Proposed Alternative to Requirements of OMa-1988,Part 10,Section 4.2.2.3 for 21 Category a Reactor Coolant Sys Pressure Isolation Valves U-603091, Monthly Operating Rept for Sept 1998 for Clinton Power Station,Unit 1.With1998-09-30030 September 1998 Monthly Operating Rept for Sept 1998 for Clinton Power Station,Unit 1.With ML20153F9871998-09-17017 September 1998 Safety Evaluation Accepting 980225 Proposed Rev 26 to Illinois Power Nuclear Program Qam ML20151U1391998-08-31031 August 1998 Monthly Operating Rept for Aug 1998 for Clinton Power Station,Unit 1 ML20237E3991998-08-27027 August 1998 SER Accepting Licensee Response to NRC Bulletin 95-002, Unexpected Clogging of Residual Heat Removal Pump Strainer While Operating in Suppression Pool Cooling Mode, for Clinton Power Station ML20237A1521998-08-0707 August 1998 SER Re Mgt Services Agreement at Clinton Power Station. Approval Under 10CFR50.80 Not Required ML20151Y6591998-07-31031 July 1998 Monthly Operating Rept for July 1998 for Clinton Power Station,Unit 1 U-603033, Part 21 Rept 21-98-039 Re Shrinkage of Medium & High Density Silicone Seals Designed & Installed by Bisco Using Dow Corning Sylgard 170 Matl.Caused by Coefficient of Thermal Expansion.Will Inspect & Rework/Repair Suspected Seals1998-07-20020 July 1998 Part 21 Rept 21-98-039 Re Shrinkage of Medium & High Density Silicone Seals Designed & Installed by Bisco Using Dow Corning Sylgard 170 Matl.Caused by Coefficient of Thermal Expansion.Will Inspect & Rework/Repair Suspected Seals U-603041, Monthly Operating Rept for June 1998 for Clinton Power Station,Unit 11998-06-30030 June 1998 Monthly Operating Rept for June 1998 for Clinton Power Station,Unit 1 ML20151U1501998-06-30030 June 1998 Revised Monthly Operating Rept for June 1998 for Clinton Power Station,Unit 1 U-603023, Monthly Operating Rept for May 1998 for Clinton Power Station,Unit 11998-05-31031 May 1998 Monthly Operating Rept for May 1998 for Clinton Power Station,Unit 1 U-603014, Special Rept:On 980512,lightning Struck Primary Meteorological Monitoring Instrumentation Tower Damaging 60- Meter Wind Speed & Associated Transmuter Circuit Card. Surveillance Testing Performed1998-05-28028 May 1998 Special Rept:On 980512,lightning Struck Primary Meteorological Monitoring Instrumentation Tower Damaging 60- Meter Wind Speed & Associated Transmuter Circuit Card. Surveillance Testing Performed ML20236E7991998-05-26026 May 1998 Final Part 21 Rept Re W Dhp Circuit Breaker Auxillary Switch Operating Assembly Anomalies.Caused by Loss of Breaker Safety Function.Dhp Circuit Will Be Inspected ML20248F3531998-05-21021 May 1998 Part 21 Rept Re Electronic Equipment Repaired or Reworked by Integrated Resources,Inc from Approx 930101-980501.Caused by 1 Capacitor in Each Unit Being Installed W/Reverse Polarity. Policy of Second Checking All Capacitors Is Being Adopted U-603004, Part 21 Rept Re 980107 Determination That Itt Barton Model 580A Series Differential Pressure Indicating Switches Operating Forces Too Low.Manufacturing Sys Allowed Switches to Be Mixed.Evaluation Concludes Issue Not Reportable1998-05-15015 May 1998 Part 21 Rept Re 980107 Determination That Itt Barton Model 580A Series Differential Pressure Indicating Switches Operating Forces Too Low.Manufacturing Sys Allowed Switches to Be Mixed.Evaluation Concludes Issue Not Reportable ML20216A9601998-05-0808 May 1998 Part 21 Rept Re Failure of 12 Volt DC Inverter Power Supply. Caused by Inadequately Sized Output Transistor Pair Combined W/Degraded Capacitors.Licensee Plans to Replace All Output Transistors & Degraded Capacitors U-602995, Part 21 Interim Rept 21-98-021 Re Deficiencies in Matl Dedication Process Used by Goulds Pumps During Use of Portable Metal Analyzer.Util Identified Discrepancies Which Are Acceptable W/Some Exception of Some Replacement Parts1998-05-0505 May 1998 Part 21 Interim Rept 21-98-021 Re Deficiencies in Matl Dedication Process Used by Goulds Pumps During Use of Portable Metal Analyzer.Util Identified Discrepancies Which Are Acceptable W/Some Exception of Some Replacement Parts U-603006, Monthly Operating Rept for Apr 1998 for Clinton Power Station,Unit 11998-04-30030 April 1998 Monthly Operating Rept for Apr 1998 for Clinton Power Station,Unit 1 U-602994, Part 21 Rept Re Final Rept 21-98-008,on 980113,reliance Electric Motors Supplied by Rockwell International for Hydrogen Recombiner Cooling Fans Do Not Have nameplate- Specified High Temperature Bearings.Fan Motors Acceptable1998-04-29029 April 1998 Part 21 Rept Re Final Rept 21-98-008,on 980113,reliance Electric Motors Supplied by Rockwell International for Hydrogen Recombiner Cooling Fans Do Not Have nameplate- Specified High Temperature Bearings.Fan Motors Acceptable ML20216B1351998-04-21021 April 1998 Rev 0 to Illinois Power Co Clinton Power Station SVC Design Rept U-602979, Final Part 21 Rept 21-97-059 Re Discrepancies Found During Receipt Insp of Three Refurbished safety-related W Dhp Circuit Breakers.Util Completed Evaluation,Per 10CFR21 & Concludes That Condition Is Not Reportable1998-04-0707 April 1998 Final Part 21 Rept 21-97-059 Re Discrepancies Found During Receipt Insp of Three Refurbished safety-related W Dhp Circuit Breakers.Util Completed Evaluation,Per 10CFR21 & Concludes That Condition Is Not Reportable U-602976, Monthly Operating Rept for Mar 1998 for Clinton Power Station1998-03-31031 March 1998 Monthly Operating Rept for Mar 1998 for Clinton Power Station ML20217H5771998-03-27027 March 1998 Safety Evaluation Concluding That No Significant Safety Hazards Introduced at CPS for Net 32% Ampacity Derating Factor for 1 H & 3 H Conduit Fire Barrier Sys & 1 H Cable Tray Fire Barrier Sys.Requests Response Addressing Issue U-602968, Interim Part 21 Rept 21-97-055 Re Westinghouse Dhp Circuit Breaker Auxiliary Switch Operating Assembly Anomalies. Initially Reported on 980116.Util Currently Evaluating Suppliers Response to Questions Re Issue1998-03-24024 March 1998 Interim Part 21 Rept 21-97-055 Re Westinghouse Dhp Circuit Breaker Auxiliary Switch Operating Assembly Anomalies. Initially Reported on 980116.Util Currently Evaluating Suppliers Response to Questions Re Issue U-602960, Part 21 & Deficiency Rept Re Commerical Grade Dedication Program of Sentry Equipment Corp.Initially Reported on 980217.IP Performed an Addl Assessment at Sentry Facility on 980226.Next Rept Will Be Submitted by 9804111998-03-12012 March 1998 Part 21 & Deficiency Rept Re Commerical Grade Dedication Program of Sentry Equipment Corp.Initially Reported on 980217.IP Performed an Addl Assessment at Sentry Facility on 980226.Next Rept Will Be Submitted by 980411 U-602954, Interim Part 21 rept,21-98-008 Re Identification That Bearings Installed in Hydrogen Recombiner B Cooling Fan Motor 0HG04CB Were Not Same as Bearings Specified on Motor Nameplate.Will Complete Evaluation of Issue by 9805131998-03-0909 March 1998 Interim Part 21 rept,21-98-008 Re Identification That Bearings Installed in Hydrogen Recombiner B Cooling Fan Motor 0HG04CB Were Not Same as Bearings Specified on Motor Nameplate.Will Complete Evaluation of Issue by 980513 1999-09-30
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V ,
4 lihnots Power Company Clinton Power Station
, P O Box 678 II 3 e 81 -
ILLINSIS u co2i93 P4WER uv.93(io4 2 >te 8E.110c October 12, 1993 ;
Docket No. 50-461 10CFR50.36 Document Control Desk i Nuclear Regulatory Commission Washington, D.C. 20555
Subject:
Special Report: Valid Test Failures ofDivision II l Diesel Generator at Clinton Power Station ' CPS.)
1
Dear Sir:
Clinton Power Station (CPS) Technical Specification 4.8.1.1.3 requires all diesel l generator failures, valid or non-valid, to be reponed to the NRC within 30 days pursuant to Specification 6.9.2, SPECIAL REPORTS Due to a valid failure of the Division II .,
Diesel Generator (DGI A) during surveillance testing on September 27,1993, the attached Special Repon is being submitted in accordance with the CPS Technical Specifications to -
provide the information required by Regulatory Guide 1.108, Revision 1, " Periodic .
Testing of Diesel Generator Units Used as Onsite Electric Power Systems at Nuclear Power Plants," Regulatory Position C.3.b.
Submittal of this letter satisfies the requirements of CPS Technical Specifications !
4,8.1.1.3 and 6.9.2 for submitting a Special Report for September 27,1993 diesel generator failure. j Sincerely yours, ,
//M
- Richard F. Phares Director, Licensing 1 JLP/nis Attachment l
cc: 'NRC Clinton Licensing Project Manager NRC Resident Office, V-690 Regional Administrator, Region III, USNRC Illinois Department ofNuclear Safety l
. n n n es a 9310190152 931012 E g t PDR ADOCK 05000461 Ci y i3 I S PDR iij
(
Special Report .
This Special Report addresses the valid failure of the Division 11 Diesel Generator (DG1B) which occurred on September 27,1993. Specific information on the. event is provided below.
Description of Event /Cause of Failure At approximately 1731 hours0.02 days <br />0.481 hours <br />0.00286 weeks <br />6.586455e-4 months <br /> on September 27,1993, DG1B was started for i surveillance per Clinton Power Station (CPS) Procedure 9080.22, " Diesel Generator IB- ,
ECCS Integrated." This procedure is normally performed when the plant is in cold shutdown or refueling to satisfy CPS Technical Specification requirement 4.8.1.1.2.e.8.
During the performance of Section 8.2, which demonstrates that the diesel .;
generator starts and reaches rated voltage and frequency within 12 seconds of an emergency core cooling system (ECCS) test signal, the diesel generator failed to reach its rated voltage of 4160 volts (+/- 10%). The actual voltage achieved was 3595 volts, which was less than the minimum voltage of 3740 volts. ,
When Operations determined that the voltage was less than the minimum required f to meet the Technical Specifications, voltage was manually raised by adjusting the voltage regulating potentiometer. Voltage immediately increased to 4100 volts. Maintenance ;
work request (MWR) D53606 was written to initiate investigation and corrective ,
maintenance on the voltage regulating potentiometer. During maintenance '
troubleshooting it was found that the potentiometer contacts were not making full contact ;
in a range corresponding to 3500 volts to 4100 volts. Cleaning the contacts did not correct the problem, however adding slight finger pressure to the contacts allowed full contact to be made and the potentiometer tested satisfactorily. The cause of the failure has been determined to be insuflicient contact pressure between the contacting surfaces. L i
i r
Corrective Action Condition Report (CR) 1-93-09-033 was written to investigate the root cause and ,
corrective action for the diesel generator failure. The potentiometer had exhibited normal i end-of-life wear as evidenced by var and amperage oscillations during a monthly surveillance in December 1992. The potentiometer was replaced in July 1993, under i MWR D32555, with an in-stock potentiometer received in 1987, and was the only item in stock. Subsequent starts of the diesel were conducted satisfactorily until the September 27,1993 failure. Discussions with the manufacturer and researching the NPRDS data i base for similar occurrences have confirmed that this type of failure has occurred in the l past at other nuclear facilities. However, this type of failure has never occurred at CPS. l The manufacturer stated that contact pressure checks to improve the component's j r
~
, reliability have been implemented recently at the factory, however, because of the age of the item in stock, it was determined that the failed component never received the factory check.
The failed voltage regulating potentiometer was replaced on DG1B on September 28,1993, with a potentiometer which had received the contact pressure check in the factory and the diesel was verified to satisfactorily stan using CPS Procedure 3506.01,
" Diesel Generator and Support Systems." A surveillance to meet the Technical Specification requirement to demonstrate the ability of the Division II diesel generator to reach the required rated voltage was performed on September 29,1993.
At the next scheduled inspection of Divisions I and III diesel generators, the potentiometers will be inspected, tested, and replaced, if necessary. Also, the manufacturer has stated that contact pressure checks have been instituted which should minimize the potential for failures in future replacements. This failure is being investigated under 10CFR21, and should it be determined that the failure is reponable, a separate report will be submitted.
Testine Intervals This failure of DGlB was only the fourth valid failure in its last 100 stans. The last valid failure of the Division II diesel generator occurred on March 28,-1992, when the electronic governor control power supply failed during routine maintenance operations.
This was only the first valid failure of DGlB in its last 20 starts. Since the number of valid -
failures in the last 20 starts is less than two, no increase testing from the current monthly frequency is required.