ML20197C909

/03L-0 on 781031:during Procedure HNP-2-10531 & Reactor in Run Mode,The 2R43-S001 C Diesel Failed to Reach 250 RPM W/In 7 Seconds,Due to Faulty Elec Speed Switch Signal

ML20197C909
Person / Time
Site:	Hatch
Issue date:	11/14/1978
From:	Nix R GEORGIA POWER CO.
To:
Shared Package
ML20197C904	List: ML20197C909 PM-78-447, Forwards LER 78-060/03l-0
References
LER-78-060-03L, LER-78-60-3L, NUDOCS 7811210243
Download: ML20197C909 (3)

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2 liliib _thLtel.icien ia_theJ1UD_DeIJe. uhile perfoccin0_prncedurc_JEIP 911051L(LDsP- Tnst) I a [t_he 2R4%S001 C diesel failed to reach Pm50 R.P.M. within 7 serovds due to a f aulty l 4 [qlec tronic_ soeed suitch siona1. Thr.cc _ day.s_ prior _tO_.thi ___in::.idatLthe_2C_ die *1 haa J t> If ailed to reach 250 R.F.M. in 7 seconds. becstase of_ wha t was_djltanosed at the time I ')

i c Lt.o_be a sf_ic11na_r.torernorJiaaster Servo hut was_jn all_ptnbabil.ityy_1hn cpned j

? Iswi tcl1 a1s.o. There were no ornbuhle_cnnsequenc.es._as_thttrcdund. ant A.C. som ces wero I io (demonstrated ongra bl e_DElc.chnic.aLS;.tecific.alions _ 4. 8.1.1.1. a a nd 4J1 1.1 2 a 4 ( ennt.ll O 8 9 SYST E M CAUSE CAUSE COMP. VALVE CODE CODE SUitCODE COMrONENT Col >E SUDCODE SUBCODE l 8 8 D I E l F10 l @ l B l@ l12A l @ l r l N l 0 l I l N [ F 18 iz_J @ LZJ li 13 til -

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44 47 cAUSE DESCRIPTION AND CORRECTIVE ACTIONS h O lan October 28_, 1978, when the first failure occurred, the Governor Booster Servo I  :

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ii [was disassembled and cleaned. The normal surveillan4e was then certormed and fnund I

g pcceptable. When the second failure occurred, the sneed switch (rat ed at 115 VJC. I l

[$i l130 VCC maximum inout) had to be renlaced with a switch rated at 115 VDC,144 VOC l t4 [ maximum input because of the 140 VoC used for eauali7ing the diescl baHeries. (cont) I 8 9 80

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! Georgia Power Conpany Plant E. I Hatch Baxley, Georgia 31513 i

C l-Reportable Occurrence tio. 50-366/1978-60

i. Event Description (cont.) l j Public health and safety were not affected by either incident.

{ Cause Description (cont.)

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IIARRATIVE REPORT Reportable Occurrence flo. 50-366/1978-60 l

On October 28, 1978, wi th the reactor at 45% power, the 2R43-S001C diesel generator failed to reach 250 R.P.M. within 7 seconds while performing procedure ICIP-2-3801 (Diesel benerator Manual Start). The problem was diagnosed at the time to be a stuck Goverme Dooster Servo. The Servo was disassembled and thoroughly cleaned. Af ter the Servo was reassembled and functionally tested, procedure ICIP-2-3801 was performed and found acceptable.

- The 2C diesel failed to reach 250 R.P.M. within 7 seconds again October 31, 1978, with the reactor at 215 po'ier. This occurred while performing procedure llHP-2-10531 (Loss of Turbine Generator and Of f Si te Power). Further investi-gation into the increased starting time revealed that the Electronic Speed Switch was giving intermittent faulty signals. Although the switch had not l completely broken down, there was evidence of continued overheating which had apparently been happening for some time. The overheating was due to the switch being rated for 115 VDC (130 VDC maximum input) and the design not tak.ing into account a 140 VDC charging voltage used to equalize the diesel generator batteries.

Please note that in each case the diesel did start and was probably above 250 R.P.M. each time the crank failure occurred. The faulty speed switch :l not indicating correct 1/ did not satisfy t.he start failure timer when the 'l diesel reached 250 R.P.M. !l l

There was not probable consequences.on either occurrence as the redundant A.C. sources were demonstrated operable per Technical Specifications 4.8.1.1.1.a and 4.8.1.1.2.a.4. Public health and safety were not aff ected by either incident.

An investigation of the other ."like" diesel at Plant Hatch revealed that it already had a speed switch With a serial rumber greater than 97000.

flo further action is required.

The following information was given by Fairbanks:

horse in regard to the Electronic Speed Switches. The switches are manufactured by the Synchro-Start Products Company and are a model ESSB-2AT. Switches that have a serial number less than 97000 are rated at the 130 VDC maximum input and the switches having a serial numt;er greater than 97000 are rated at 144 VOC maximum input. Iairbanks Morse also implied that there have been other utilities with problems relating to the diesel ba ttery equalizing voltage.

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