ML19329F947

Revised LER 79-126/03L-1:on 791209,during Diesel Generator Test,Generator 1-1 Experienced Load Swings as Load Was Increased.No Specific Cause Determined.Gain & Stability on Electric Governor Needed Slight Adjustments

ML19329F947
Person / Time
Site:	Davis Besse
Issue date:	01/05/1980
From:	Hartigan J TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19329F944	List: ML19329F943 ML19329F947
References
LER-79-126-03L, LER-79-126-3L, NUDOCS 8007110397
Download: ML19329F947 (2)

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, LICENSEE EVENT REPORT (PLEASE PRINT OR TYPF ALL REQUIRED INFORMATION)

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EVENT DESCRIPTION AND PROB ABLE CONSEQUENCES h 10121 1 On December 9, 1979, during the performance of Diesel Generator, (DG) Monthly Test, [

TIT 1 l DG l-1 experienced load swings as the load was increased above 1000 KW and again when '

l o l 4 l l the load was increased to 2500 KW. During maintenance investigation, an electrician l lalsl [ mistakent . racked out the wrong breaker which made DG l-2 Inoperable. For 20 minutes l

!O ls l l the station was in viointion of Technical Specification 3.8.1.2 (without a DG). l lo I 7 l l There was no danger to the health and safety of the public or station personnel. Off-j

[TUi-] l site power was available to safety systems in the plant. (NP-33-79-146) l 80 7 8 9 E CODE SU8CO E COMPONENT CODE SUBC DE - ODE lTB] l El El@ lA l@ l G l@ [0, l K l T l B l R l K l@ {@20y @ 18 19 7 8 9 10 11 12 13 SE QUENTI AL OCCU R RE NCE REPORT REVISION EVENT YEAR REPORT NO. CODE TYPE N O.

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43 44 47 CAUSE DESCRIPTION AND CORRECTIVE < CTIONS jijoli On 12/9/79 under Maintenance Work Order 79-3730, the load swinging proble .eas inves-l i i [ tigated by station personnel, but no specific cause was determined. Diesel Generator!

, , i Monthly Test was rerun successfully later the same day. The vendor investigated on I 1/7/80 and found the need for only slight adjustments .o the gain and stability on l gl

, ;4 i l the electronic governor. l 1 8 9 80 ST S  % POWER oTHER STATUS ISCOV RY DISCOVERY DESCRIPTION l1l5l W@ l 0l 0l 0l@l NA l l A l@l operator observation l ACTIVITY CO TENT REMASED OF RE M ASE LOCATION OF REMASE ti Io18 9trJ @ lz_]@lNA 10 AMOUNT OF ACTIVITY 44 l

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• TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-79-1,4_66 DATE OF EVENT: December 9, 1979 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE:

Swinging load on Diesel Generator 1-1 and rackout of wrong Diesel Generator output breaker Conditions Prior to Occurrence: The unit was in Mode 5, with Power (MRT) = 0, and Load (Gross MWE) = 0.

Dascription of Occurrence: While performing ST 5081.01, Diesel Generator (DG) Monthly Surveillance Test on DG 1-1 the load started swinging from 1000 KW to 3000 KW as load was raised above 1000 KW. The operator stopped raising the load to inspect the voltage regulator, and the load swinging ceased. The load was then raised to 2500 KW. A few minu'tes later, the load started swinging from 1800 KW to 3500 KW at which time DG l-1 was shutdown. About an hour later DG l-1 was restarted so naintenance could check out the electronic governor. The unit was running at 2500 KW for about 35 minutes and thin started to swing irom 800 KW to 3000 KW. The unit was unloaded and removed from service.

At this time, the Shift Foreman instructed a plant electrician to rack out AC101, DG l-1 output breaker. The electrician mistakenly racked out AD101, DG l-2 output breaker.

Approxinately 15 minutes later, it was noticed that AD101 was racked out instead of AC101. AD101 was promptly racked in and AC101.was racked out. For approximately 20 ninutes, the station was in the action statement of Technical Specification 3.8.1.2 which requires one DG to be operable in Modes 5 or 6.

Designation of Apparent Cause of Occurrence: At the time of the occurrence, mainten-ance was not able to pinpoint the cause. On January 7, 1980, the vendor, Power Systems, came on site and found the need for a small adjustment to the gain and stability of the electronic tovernor which improved the engine response.

The occurrence of the electrician racking out the wrong breaker has been designated a personnel error.

-1 Corrective Action: On December 9, 1979, a small amount of oil was added to the gov-ernor, and ST 5081.01 was successfully run later the same day. Diesel Generator 1-1 was declared operable. Maintencnce Work Order 79-3730 was issied to troubleshoot the load swinging problem. On January 7,1980, the vendor, Powar Systems, came on cite and made a small adjustment to the gain and stability of the electronic governor which improved the engine response.

Personnel involved were instructed as to the proper communication to be established when performing equipment switching.

Failure Data: A similar problem was found on DG l-1 as detailed on Licensee Event Report _NP-33-78-58..

LER #79-126 L a

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