ML20065U432
| ML20065U432 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 12/27/1990 |
| From: | Cottle W ENTERGY OPERATIONS, INC. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 90-003-00, 90-3, NUDOCS 9101020329 | |
| Download: ML20065U432 (4) | |
Text
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e, Eniergy P'P ?~"a"* '"'-
Operations p
W. T. Colne uccember 27, 1990 U.S. Nuclent Reguintory Commission Hntl Station PI-l'87 Washington, D.C.
20555 At t etit ion !
Docurient. Cotit rol Desk SUIVI.CT :
Otand Gulf Nucient Stntion Unit 1 Docket No. 50 416 hicenne No. NPF-29 Specint Report 90-003*00 Emergency Diesel Generator 11 Failure GNRO-90/00012 Gentlement On November 27, 1990 at approxjmntely 1226 hours0.0142 days <br />0.341 hours <br />0.00203 weeks <br />4.66493e-4 months <br />, plant operators'at nrt ed D{ct.el Geneintor 11 (Division 1) for performance of the monthly functiorni n r.ellinnce in accordance wit.h Techn t en ! Speicl(ica t ion 4.8.1.1.2.
The dleseI was succen9 fully ritnrte<l and lontled to approxfmntely 350 kf';wnttn (KW) nt 1233 hours0.0143 days <br />0.343 hours <br />0.00204 weeks <br />4.691565e-4 months <br />.
While at t he 350 KW lond, opera t ors at. the locnl dienol generatot pnnel observed oscillat ions of about S volts (10 volt s penk to penk) on t he genernt or fielei volt age inst rument.
A nivallor variation occurred at apprcx imn t e l y 1000 KW, i nc rorrent n l londing of t he generat or was cont inued w it hout signitiennt obnormnl varintionn.
At approximat.cly 1255 hours0.0145 days <br />0.349 hours <br />0.00208 weeks <br />4.775275e-4 months <br /> wit h t he genntator loadert nt 5000 KW nnd stable, in ga oscillations of generator field voltage, field current and output curren' were dispinyed on t he local cont rol panel.
Indications on these instruments then pegged upscale and returned to nont normal range, and then pegged upscale nhout twenty seconds later at which time the generntor output brenker tt ipped. The diesel continued to run unt il it was marwally shut down by operntors.
The diesel generator was t. hen secured for correct (vo maintennnen.
Immedinte investigation into this fal}ure revenled that thn gennrntor field voltage slip rings dispinyed more t han expected amotuit*, of carbon deposits.
The voltage regulat or circuit in service nt the time 01 *he f a i l u r e (.l. c., lit idge 1) was in.itfully suspected to have caused the iniled run.
VisunI luspect ion of that cf rcuit was performed.
No fniled component was observed during the search lot the u nse of
- t. h e malfunction.
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o December 27, 1990 i.
GNRO-90/00012 page 2 of 4 Upon clo9ning the genorntor slip rings and sotting the generator voltage regulator system to the redundant circuit. (1.o., Bridge 2), a Lost run 9f the diosol generator commenced at 1642 hours0.019 days <br />0.456 hours <br />0.00271 weeks <br />6.24781e-4 months <br /> and was performed
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successfully. The failuro symptoms did not recur with the voltage j
i regulator system in the Bridge 2 circuit.
The diosol gonorator operability surveillanco commenced at 1836 hours0.0213 days <br />0.51 hours <br />0.00304 weeks <br />6.98598e-4 months <br />.
The diosol generator was declared operable at 2158 hours0.025 days <br />0.599 hours <br />0.00357 weeks <br />8.21119e-4 months <br /> on November 27, 1990.
i Subsequent troublonhooting investigations worn performed on December 11, 1990.
Components nnd assemblirss inspected worn the carbon brushos;-
carbon brush springs forcot ole trical resistance of relay contacts for generator field voltage foodback circuit to the voltnge regulator; and electrical resistance of contacts for the governor droop rolny.
4 Strip chart recordings woro endo of generator field voltage and current i
. and generator output-voltago and curront during t roubleshoot ing runs of the diesel gonorator with the voltage regulator system in t.he Drtdge I ci rcu i t..
Troubleshoot.ing runs subjected the diosol generator to various operating conditions utilir.1ng thn same controls in service when the valid failure occurred.
Attempts to repent the in11uro woro unsuccessful. bonds varied f rom zero to fully loaded r.nd synchronized on the grid. Again, no abnormal parnmotors wnro Indicated on Instrumentation or recordingr.
Due to the absence of a repentoci failuro whilo troubleshooting, it is suspected that the carbon deposits on the generator slip rings may have boon the causo..The frequency of the conorator carbon brush and slip ring Inspection will be incronned f rom an annual to a quart erly inspect lon. _ In addition, periodic cycling of the voltago regulator bridge rolay will be performed.
Monitoring of the diosol generator will l
he performed to provido addit.lonnl assuranco that correctivo actions taken nro-offactivo.
Entergy Operations, Inc. considorod the test to be a valid failure pursuant to position 0.2.o(5) of the Regulatory Guido 1.106 sinco the ability of the dional generator in this condition to power ESP loads in i
I respcaso to a bonaf fdo signal was indotorminato.
This was the first
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valid failuro in the Inst. 20 test s and t.ho fif th in t.ho last 100 valid tests.
Thorofore, the testing frequency was increased to onco por 7 days i
_in accordance with the tost _ schedule of Technical Spanffication Tablo 4.8.1.1.2-1.
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December 27. 1990 GNRO-90/00012 Page 3 of 4 This Special Report is submitted pursuant to Technical Specificntion 4.8.1.1.3.
Y uro ruly, s
h D T C A Ls
'/BAP/tkm cc:
Mr. D. C. Ilintz Mr. J. Mathis Mr. R. II. McGehen Mr. N. S. Reynolds M r. 11.
1,.
't homa s Mr. Stewart D. Ebneter Regionni Administratne U.S. Nucient Regulatory Commisajun Region 11 101 linrietta St., N.W., Sui t e 2900 Atlanta, Georgin 30323 Mr. i,. l..
Kintner, Project Mannger Of fice of Nuclent Renctor Regulntton U.S. Nucionr Regulatniy Commission Mail Stop 11021 Washington. D.C.
20555 l
G9012261/SNI1CFI.R - 3 1
December 27. 1990 GNRO-90/00012 Pago 4 of 4 bcc:
M r. 11 A. Burke Hr. H. A. Dietrich Mr. C. R. Ilutchinson Ms. F. K. Mangan Mr. H J. Holsner Mr. G. W. Huench Mr. T. E. Renvos Mr. J. L. Robertson
.Mr. F. W. Titus Mr. G. A. Zinke File (LCTS)
File (llard Copy)
Filo (RPTS)
Filo (NL)
Filo (Contral) ( 8
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