05000334/LER-1991-023, Forwards Corrected Copy of ,Transmitting LER 91-023-00.Ltr ND3MNO:3179 Should Have Been ND3MNO:3194

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Forwards Corrected Copy of ,Transmitting LER 91-023-00.Ltr ND3MNO:3179 Should Have Been ND3MNO:3194
ML20079F780
Person / Time
Site: Beaver Valley
Issue date: 09/04/1991
From: Noonan T
DUQUESNE LIGHT CO.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
ND3MNO:3194, NUDOCS 9110080270
Download: ML20079F780 (1)


LER-2091-023, Forwards Corrected Copy of ,Transmitting LER 91-023-00.Ltr ND3MNO:3179 Should Have Been ND3MNO:3194
Event date:
Report date:
3342091023R00 - NRC Website

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Beaver Valley Power Station, Unit 11o. 1 Docket 11o. 50-334, License lio. DPit-66 1111 9L D11-QO United States !!uclear Regulatory commission Document Control Denk Washington, DC 20555 Letter ND3MNO:3179 -

1E11 91-023-00 Unit. No. 1, innued on August 26, 1991 was an incorrect letter number. It uhould have b e e n 11 D 3 M 11 0 : 3 1 9 4 .

A corrected copy in attached.

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T. P. lloonan General Manager Nuclear Operations TPfl/sl Attachment l,)~

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- VBfd Augunt 26, 1991 11D314140: 3194 Beavor Valley Power station, Unit llo. 1 Dochet IJo. 50-334, Licence No. DPR-66

_ ,LQLEh013 -00 United Stateu 11uclear Regulatory Commission Document Control Doch Washington, DC 20555 Gentlemen:

In accordance with Appendix A, llo av e r Valley Technical Specifications, the following Licennee Event Report is submitted:

LER 91-023-00, 10 CI'R 50.73.a.2.iv, " Reactor Trip Due to Electro-llydraulic Control System Malfunction".

Very truly yours, s, n 3 $ w + / . p t.

l T. P. floonan Cencral 14anager 11uclear Operationn Jill'/ s l Attachment p.

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August 26, 1991 ND3MNO 3194

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cc Mr. T. T. Martin, Regional Administrator -

United States Nuclear Regulatory Commission i Region 1 475 Allendale Road  !

King of Prussia, PA 19406 C. A. Rotock, Ohio Edison 76 S. Main Street Akron, OH 44300 Mr. A. DeAgazio, BVPS Licensing Project Manager United States Nuclear Regulatory Commission

-Washington, DC 20555 +

J. Beall, Nuclear Regulatory Commission,  !

BVPS Senior Resident Inspector

- Larry Beck Centerior Energy- ,

6200 Oak Tree Blvd.

Independonce,-Ohio 44101-4661 INPO Records Center Suite 1500 i

- 1100 circle 75 Parkway ,

Atlanta, GA 30339 G. E. Muckle, Factory Mutual Engineering 680-Anderson Drive #BLD10 Pittsburgh, PA 15220-2773 ,

i Mr. Richard-Janati Department of Environmental Resources P. O. Box 2063 16th Floor, Fulton Building Harrisburg, PA 17120 Director, Safety Evaluation & Control t Virginia Electric & Power Co.

P.O. Box 26666 One James River Plaza Richmond, VA 23261 W. Hartley Virgi'nia Power Company 5000 Dominion. Blvd. -

c 2SW Glenn Allen, VA 23060 J. M. Riddle -

NUS Operating Service Corporation r Park West II >

Cliff Mine Road Pittsburgh, PA 15275 i

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August 26, 1991 ND3MNO:3194 Pago three Bill Wegner, Consultant 23 Woodlawn Terrace Fredricksburg, VA 22404

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On 7/26/91 at 1930 hours0.0223 days <br />0.536 hours <br />0.00319 weeks <br />7.34365e-4 months <br /> in o erating Mode 1 at 30 percent power the unit began to oscilkations from the turbine experonceturbine$overnorcontrol Electro-Hydraul c Control (EHC) system. Between 1930 hours0.0223 days <br />0.536 hours <br />0.00319 weeks <br />7.34365e-4 months <br /> 7/36/91 and 0655 hours0.00758 days <br />0.182 hours <br />0.00108 weeks <br />2.492275e-4 months <br /> 7/27/91, three load rejections of between 100 and 150 MWe were e orienced. Operators stabilized the plant after each load re action. EHC troubleshooting by plant personnel and contractor technicians began after the first occurrence. After the third occurrence, station management decided to remove the

, turbine from service in accordance with the Abnormal operating Procedura for a load rejection. During preparations for shutdown, a fourth load rejection, accompanied by erratic turbine governor valve control, occurred. The reactor tripped at 0713 hours0.00825 days <br />0.198 hours <br />0.00118 weeks <br />2.712965e-4 months <br />, due to a low level coincident with a low feedwater flow in the "B" steam generator. Control room personnel stabilized the plant in Operating Mode 3. The spurious- governor valvo signals were due to loose connections in the EHC cystem. There were no safety implications to the public as a result of this event. All sautdown and control rods inserted, and all plant systems responded as designed.

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DESCRIPTION OF EVENT on 7/26/91 at 1930 hours0.0223 days <br />0.536 hours <br />0.00319 weeks <br />7.34365e-4 months <br /> while in operating Mode 1 at 30 percent power, the Unit began to experience turbine governor control oscillations from the turbine Electro-Hydraulic Control (EHC) system. The governor valve control signal fluctuated, resulting in a 100 MWe load rejection. The governor valve position limiter was reduced by the operators and the plant was stabilized. Contractor EHC technicians were contacted to ascist in troubleshooting. On 7/27/91 at 0315 hours0.00365 days <br />0.0875 hours <br />5.208333e-4 weeks <br />1.198575e-4 months <br /> the Speed Error "A" card in the EHC cabinet was replaced.

At 0511 hours0.00591 days <br />0.142 hours <br />8.449074e-4 weeks <br />1.944355e-4 months <br /> on 7/27/91, a second ISO MWo load rejection occurred when the governor valve control signal failed to zero and then returned to its original output approximately forty"five seconds later. A technician from the EHC contractor had opened the door in the EHC cabinet during this time and reclosed the cabinet door just as the load rejection was announced throughout the station. Control room personnel stabilized the plant by folioving Abnormal operating Procedure (AOP) 1.35.2, " Load Rejection / Loss of Eltetrical Load."

A third load rejection of 150 MWe oc. curred at 0655 hours0.00758 days <br />0.182 hours <br />0.00108 weeks <br />2.492275e-4 months <br />.

Operators stabilized the plant .and station management decided to remove the turbine from service in accordance with AOP for a load re:iection. While preparing to shutdown the Unit, a fourth load re:lection coupled vita erratic turbine governor valve control, was experienced. The reactor tripped at 0713 hours0.00825 days <br />0.198 hours <br />0.00118 weeks <br />2.712965e-4 months <br />, due to a low level coincident with a low feedwater flow in the "B" steam generator. Control room personnel entered Emergency operating Procedure E-0, " Reactor Trip and Safety injection" and transitioned to procedure ES-0.1, " Reactor Trip Response" after verifying that a Safety Injection signal was not required. The plant was stabilized in Hot Standby (Operating Mode 3).

CAUSE OF THE EVENT A contractor specializing in EH control systems was contacted to assist treubleshooting the EHC system. The technicians concluded that the governor valve closures were the result of losing the governor valve common signal GV*AZ1 on mixing amplifier 2P02F. This amplifier is the final driver to all four governor valves. The card was found not to be fully inserted into its slot. The technician inserted the card and verified proper output. Additional wire connections and contacts were checked and tightened. The spurious governor valve signais vere attributed to the loose connections found and corrected during the troubleshooting effort. After a confidence run, the reactor was taken critical on 7/27/91 at 2130 hours0.0247 days <br />0.592 hours <br />0.00352 weeks <br />8.10465e-4 months <br />.

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"** " t ' i' ." L*.B J Beaver Valley Power Station Unit 1 oplololol3l3f 9 l1 __0p 0 l3 os Op 0 l2 l3 vin >. . .-. . ..c u .o m CORRECTI'lE ACTIOHS The following corrective actions have been or will be taken as a result of this event:

1. Operations personnel, utilizing the Emergency Operating procedures, stabilized the plant :.n Hot Standby.
2. An inspection and electrical check of the EHC system by station and personnel was perforned.
3. The EHC preventive maintenarv:e program will be formalized from the series of Maintenance Work Requests currently being used. The scope of the program will ba reviewed and enhancements considered where appropriate.

SAFETY IMPLICATIONS There were no safety implications to the public as a result of this event. The plant systems responded as designed (all shutdown and control rods fully inserted, turbine trip auxiliary feedwater actuatian on low-low steam generator level following steam level shrink resulting from the loss of secondary load) generator .

REPORTABILITY This event was reported to the Nuclear Ragulatory Commission at 0745 hours on 7 in accordance with the requirements of 10CFRSO.72.b.2.ii,/27/91 Reactor Protection System actuation. This written report is being submitted in accordance with 10CR50.72.iv, as an event involving a Reactor Protection actuation.

PREVIOUS OCCURRENCES There has been one previously reported reactor trip which was the result of EHC system failures, LER 87-002-00 "Heactor Trip / Turbine Trip Due to Electro-Hydraulic Control Malfunction." In this event, a failure of the Overspeed Protection Controller resulted in a turbine runback when the overspeed setpoint drifted low.

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