ML20115J112

Voluntary Report:On 960430,two Unplanned Starts of Emergency Diesel Generator (EDG) 1-2 Occurred.Caused by Failure to Perform Procedural Step to Verify Power Supply to Electrical Busses D1 & D2.Personnel Counseled

ML20115J112
Person / Time
Site:	Davis Besse, 05000345
Issue date:	07/17/1996
From:	Lash J TOLEDO EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
AB-96-0026, AB-96-26, NP-96-0007, NP-96-7, NUDOCS 9607240003
Download: ML20115J112 (2)

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TOLEDO

' EDISON .

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EDISON PLAZA 3OO MADISON AVENUE a

TOLEDO, OHIO 43652-DOO1 Docket Number 50-346 l License Number NPF-3 1

j July 17, 1996

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i 4 United States Nuclear Regulatory Commission NP-33-96-0007 I Document Control Desk AB-96-0026  ;

Washington, D.C. 20555

Subject:

Voluntary Report of Emergency Diesel Generator Starts

Ladies and Gentlemen:

During the conduct of the Tenth Refueling Outage at the Davis-Besse Nuclear Power Station sDBNPS). two unplanned starts of Emergency Diesel Generator (EDG) 1-2 occurred. These two occurrences of starting an EDG are being voluntarily reported to the NRC consistent with past reporting practice 2.nd guidance provided by NUREG 1022, Revision 1, Second Draft, i Licensee Event Report System Description of System and Guidelines for Reporting. ,

3 On April 30, 1996, a Potential Condition Adverse to Quality Report (PCAQR) documented an unplanned start of Emergency Diesel Generator 1

(EDG) 1-2. At the time of the occurrence, the reactor was defueled and

• all fuel was stored in the Spent Fuel Pool (SFP). Fuel movements were  ;

occurring in the SFP to perform inspections of fuel assembly spacer  ;

crids. Restoration from electrical bus B transfer and lockout testing '

was being performed per the 4260 Volt Switching Procedure (DB-OP-06315).

At 1813 hours0.021 days <br />0.504 hours <br />0.003 weeks <br />6.898465e-4 months <br />, electrical busses D1 and D2 were inadvertently de-energized while attempting to transfer busses D1 and D2 frcm their alternate to normal power supplies. As a result, EDG 1-2 started and re-energized essential bus D1 as designed. Fuel movement in the SFP was /

suspended and the abnormal procedure, Loss of AC Power Sources ((g (DB-OP-02521) was entered to recover from the event. At 1932 hours0.0224 days <br />0.537 hours <br />0.00319 weeks <br />7.35126e-4 months <br />, the normal D1 electrical power source was restored and EDG 1-2 was shut 17e z2 ;

down. -~

l At 2003 hours0.0232 days <br />0.556 hours <br />0.00331 weeks <br />7.621415e-4 months <br /> on April 30, a four-hour non-emergency telephone call was made via the Nuclear Regulatory Commission (NRC) Emergency Notification System (ENS) to report this event in accordance with 10CFR50.72 (b) (2) (ii) as an actuation of the Engineered Safety Features (ESF). Because the EDGs at the DENPS are not part of the pldnt ESF, no ENS notification was 1 required and the notification was retree:ed on May 22, 1996.  !

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9607240003 960717 PDR ADOCK 05000346 g PDR I

J Docket Number 50-346 License Number NPF-3 l Page 2 The apparent caur' of this EDG start was failure to perform a procedural step to verify the power supply to electrical busses D1 and D2. Personnel I involved were counseled to raise their sensitivity for attention to detail. Shift supervisory personnel were counseled relative to management oversite expectations for electrical switching evolutions performed in the Control Room.

1 On May 15, 1996, with the plant in Mode 5, EDG l-2 was inadvertently started during preparatory activities for conduct of the Channel 2 i Integrated Safety Features Actuation System (ISFAS) test. During preparations for the ISFAS test, a Data Acquisition and Analysis System ,

(DAAS) was connected in parallel with the EDG emergency start switch l contacts. The DAAS utilizes a contact isolation board with a current '

limiting thermistor. Because of the heatup characteristics of the thermistor, current limiting was delayed approximately 40 seconds after

, voltage was applied at the input leads. Due to the delay in activation of the current limiting circuit of the DAAS isolation board, enough current I

was passed (approximately 12 milliamps) to cause the emergency start relay to pick up and start the EDG.

The apparent cause of this occurrence was the connection of the DAAS to monitor contacts which momentarily passed sufficient current around the  !

switch contact to energize the downstream relays. Utilization of the DAAS l DC contact isolation board to monitor contacts on an energized circuit has been discentinued. Although connecting the DAAS caused an EDG start,  ;

there were no safety significant consequences to this action. There were l no false instrument indications produced or safety system protective i circuit functions affected. I Should you have any questions or require additional information, please contact Mr. James L. Freels, Manager - Regulatory Affairs at (419) 321-8466.

Very truly yours, m il t

! H. Lash General Manager - DB Plant Operations DLM: tam 1

cc: L. L. Gundrum, NRC Project Manager H. J. Miller, Regional Administrator, NRC Region III S. Stasek, DB-1 Senior Resident Inspector Utility Radiological Safety Board a

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