ML17252B482

LER 76-062-00 for Dresden, Units 2 and 3 Re Upon Completion of Routine Diesel Generator Surveillance Testing, Control Switch Was Placed in the Stop Position, Generator Output Subsequently Became Erratic, Generator Voltage Began Oscillating.

ML17252B482
Person / Time
Site:	Dresden
Issue date:	10/29/1976
From:	Stephenson B B Commonwealth Edison Co
To:	Keppler J G NRC/RGN-III
References
BBS LTR 76-757 LER 76-062-00
Download: ML17252B482 (3)

Text

..... Commonv.rah Edison Dresde.1 Station R.R. # *, Morris, Illinois 60450 Telepho;ie 815/942-2920 BBS Ltr. 1176-757 ., .. October *29, 1976 Mr. James G .. Keppler, Regional Director Directorate of Reg'ulatory Operations -Region III U. S. Nuclear Regulatory Commission 799 :Roosevelt Road Glen Ellyn, Illinois 60137

REFERENCES:

Docket No. 50-237 No. 50-249 , Enclosed please find Reportable Occurrence report number 50-237/1976-62. This report iS submitted to your off iCe in accordance with the Dresden Nuclear Station Technical Specifications, Section 6.6.B. BBS:jo Enclosure (A . ,-:-, t1 -z2-*-l _, c::r}/1 ; J. / /' . . *-v .._,-..._; /J '.I t.i?t* -!)--B. B. Stephenson fr Station Superintendent Dresden Nuclear Power Station cc: Director of Inspection &.Enforcement Director of Management* information & Program Control

• File/NRC

-* ....... --* ';*-------* .. ... .... -*---**--*-.___.._.......__ . **it LICENSEE EVENT REPDF9 I CONrROL Bl:OCK: ..... I __._I (PLf:.ASE PRINT ALL REQUIRED INFORMATION] LICENSEE NAME @E] 7 8 9 14 CATEGORY REPORT TYPE. 1 6 ucrnsr NUMBER 10101-10101019101-10101 15 25 RE PC RT SOURCE DOCKl;T NU.MOER LICENSE TYPE l-4ltlilllfl 26 30 EVENT DATE EVENT TYPE 10131 31 32 REPORT DATE '@E]coNT I I. I lbJ U::J Io I s I o L-Io I 2 I 3 17 J 101q 13lo17ll. I I/ 7 ' B 57 58 59 60 . 61 68 69 74 75 80 EVENT DESCRIPTION @Ifil I UPON CoMP}..E.TtDN OF RoUT1N£ UN1 T ').._h Dr GEN£RA-fop___ SuRycr L.IJCINcf: I* 7 8 9 . . . 80 f @faLJTEST1NG:, TH£ CONTROL.. S0v1TcH 'P).._P,CC:::D IN TH:G".STOP pos1T10N. . f 7 B 9 80 lo14 I THC 6-ENERAToR OUT PU/ SVBSE. QUE:NTLY ERR.41/C.. THE G-EIVE"RATOR-I 7 8 9 . . . 80 lol51 !VOLTAGE BE.Gr-,f'J osc1 L/..:..AT/NG-, AND THE AC AND De CURRENT f'l'lCTE Rs I 7 .* 8 g* . . 80 [Q]B] I WC.NT OF"F.;.SCAL£. TH£ DIESEi-G-ENE.RAToR. WAS 1wir1£DfAT£J,,Y I 7 8 9 PR:ME (St:E' .'\ITAOISD Si-IEE.T) . 80 SYSTEM CAUSE COMPONENT COMPONENT , COOE CODE COMPONENT CCJOE SUPPUEn MANUFACTURER VIOLATION @01£1£1 l[J 1£1.NIGlllNIEI lAJ IWI01lll71 w 7 8 9 10 11 12 17 43 44 47 48 CAUSE DESCRIPTION lolel .f-:n-4£ 1>1£$EJ_ Gi=.NERATOR.. Mf!J...FUNcn oN RESUt..IED [Rom A SHORTED SEJ....ENIVM 7. 8 9 . . . . . 80 lolsl !"i?f:CTIFIER. IN 1H£ GENER.ATOR. 1-1£&.D CIRCUIT, THE SHORT WflS.

• 1 7 0* g . . so :,

• 1 *,* 7* 8 9 FACILITY . . . . ... ... **. *... . . (S£it STATUS % POWER OTHER STATUS DISCOVERY DISCOVERY DESCRIPTION EID l-Gl*9 I NA U3J J\11-l I 7 B 9 10 . 12 13 44 45 4-6-----------:------'80 FORM OF . ACTIVITY

• CONTENT RELEASED

• OF RELEASE AMOUNT OF ACTIVITY E.EI lZJ l.Zl IL--_ ___;._Ni..,;,_1-1 __ ___. LOCATION OF RELEASE Nil 7 8 9 10 11 44 PERSONNEL EXPOSURES NUMBER. . TYPE DESCRiPTION jdlOIOI 7 9,9 11 lKJ NA 12 . 13 80 ., . PERSONNEL -INJURIES NUMBER DESCRIPTION

• EEllOIOIDI 7 . B 9 11 12 80 OFFSITE CONSEQUENCES }v/1 , .. 7 8 9 80 LOSS OR DAMAGE TO FACILITY TYPE . DESCRIPTION lZ.J NA 7 a g _______ PUBLICITY Em /\/11 7 B 9 80 ADDITIONAL FACTORS E@ 7 B 9 M 80

,)J EVENT DESCRIPTION (Continued) to be operable, as were the Unit-2 LPCI, core spray, and CCSW systems.. Since* the Vnit-3 diesel generator was out of service at the time, all fuel movements were suspended on Unit-3, which was in a refueling_outage, The diesel generator was manually shut down, This is not a repetitive occurrence, CA.USE DESPCRIPTION (Continued) The rectifier failure evidently resulted in damage to, a* unit. in the circuit. Both were replaced, and the Unit 2/3 tliesei genera'tor successfully tested and returned to service. Modification requests. have been initiated. t.o replace the rect_ifiers on all three diesel generators with physically large'!-unfrs that have higher voltage ratings. Installation of these higher capacity units will a §atisfactdry long-terin corrective action.

• The rectifiers are model 300U80 selenium components manufactured by International Rectifier.