05000327/LER-1983-122, Updated LER 83-122/03X-1:on 830927 & 28,diesel Generator 2A-A Declared Inoperable Due to Failure to Maintain Load of 4,400 Kw During Surveillance Testing.Caused by Faulty Exciter

Updated LER 83-122/03X-1:on 830927 & 28,diesel Generator 2A-A Declared Inoperable Due to Failure to Maintain Load of 4,400 Kw During Surveillance Testing.Caused by Faulty Exciter

ML20081G897
Person / Time
Site:	Sequoyah
Issue date:	11/01/1983
From:	Green H, Harding M, Rogers H TENNESSEE VALLEY AUTHORITY
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
LER-83-122-03X, LER-83-122-3X, NUDOCS 8311070227
Download: ML20081G897 (3)

LER-2083-122, Updated LER 83-122/03X-1:on 830927 & 28,diesel Generator 2A-A Declared Inoperable Due to Failure to Maintain Load of 4,400 Kw During Surveillance Testing.Caused by Faulty Exciter

Event date:
Report date:
3272083122R00 - NRC Website

text

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-_ .s UPDATED REPORT - PREVIOUS REPORT DATE: 10/21/83

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-l o 121 I with unit 1 in mhde 1 (loot Rv nower) at 0610 mr on 09/27/83. diesel nonerator (n/c)

[olaj ! 2A-A was declared inoperable due to failure to maintain a load of 4400 kW durinn survet !

10 i d l l ance testing. Them'echanical governor was adinsted and the D/G returned to service. Or

• loIs) (09/27/83,at 2040, b/G 2A-A was declared inoperable when the D/G tripped on high dif fer-

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' t o J s ] TTn'Tir,il cuN$nt. Troubleshooting Elid not reveal any problems, andIheD/Gwas returned l 0 ( 7 ) l service. At 1454 on 09/28/83, D/G 2A-A was declared inoperable due to a loss of the l o i s i 1 excitation transformer. Fo r ea ch even t , the unit complied with action (a) of LCO 3.8.1

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' UPDATED REPORT - PREVIOUS REPORT DATE: 10/21/83

, Sequoyah Nuclear Plant LER SUPPLEMENTAL INFORMATION SQRO-50-327/83122, Revision 1 Technical Specification Involved: 3.8.1.1 Reported Under Technical Specification: 6.9.1.13.b Date of Occurrence: 09/27/83 Time of Occurrence: 0610 CDT Identification and Description of Occurrence:

This revised report provides supplementary information to the original report and the events surrounding an incident occurring at 1802 CDT on 10/02/83.

Between 09/27/83 and 10/03/83, several incidents occurred related to the diesel generator (D/G) 2A-A and stemming from a single root cause.

On 09/27/83 at 0610, D/G 2A-A was declared inoperable due to failing to maintain a load of 4400 kW during surveillance testing. The mechanical governor was adjusted and the D/G declared operable at 1100 CDT on 09/27/83.

The D/G 2A-A was declared inoperabic at 2040 CDT on 09/27/83 when the diesel tripped on high differential current. Subsequent troubleshooting did not reveal any problems, and a restart of the diesel verified operability at 0600 on 09/28/83. Surveillance testing per SI-26 continued until 1454 CDT on 09/28/83 when the D/G was declared inoperable due to the failing of the excitation transformer. After replacement of the transformer and return of the diesel 2A-A to service, a prcblem was experf nced on 10/02/83 at 1802 CDT with the diesel output being out of frequency limits. Upon event discovery, the D/G was declared inoperable. For all the above events, the unit complied with the action statement (a) of LCO 3.8.1.1.

Conditions Prior to Occurrence:

Unit 1 in mode 1 at 100% Rx power.

Unit 2 in mode 5 at 0% Rx power.

Apparent Cause and Analysis of Occurrence:

All events reported in this revision to the LER are related to the excitation trans former. It has been concluded that the excitation transformer was faulty in that the 'B' phase saturable core and 'B' phase linear reactor in the transformer had a high leakage current. This led to the failure of the t rans fo rmer. The subsequent replacement of the transformer led to the D/G being out of frequency on 10/02/83. This, however, was not obvious at the time of the replacement.

Corrective Action:

For each event, the D/G was returned ta service within the LCO time limits.

On 09/29/83, the excitation transformer was replaced and the D/G returned to service at 1130 CDT. For the event of 10/02/83, the f requency output of the D/G was adjusted to 60 Hz and KLA field flashing relay coil was replaced.

The D/G was returned to service at 0200 CDT on 10/03/83. No further action is planned.

Failure Data:

None.

e TENNESSEE VALLEY AUTHOR Y CH ATTANOOGA, TENNESSEE 37401

//

1750 Chestnut Street Tower II 8

9 .

November 1, 1983 h Mr. James P. O'Reilly, Director U.S. Nuclear Regulatory Commission Suite 2900 101 Marietta Street, NW.

Atlanta, Georgia 30303

Dear Mr. O'Reilly:

TENNESSEE VALLEY AUTHORITY - SEQUOYAH NUCLEAR PLANT UNIT 1 - DOCKET NO. 50-327 - FACILITY OPERATING LICENSE DPR REPORTABLE OCCURRENCE HEPORT SQRO-50-327/83122 - REVISION 1 The enclosed report is a supplement to my letter to you dated October 21,

, 1983 concerning the inoperability of one diesel generator. This report is submitted in accordance with Sequoyah unit 1 TechnBal Specification 6.9.1.13.b.

Very truly yours, 4

TENNESSEE VALLEY AUTH0HITY YY $

H.J.Greef Director of Nuclear Power Enclosure oc (Enclosure):

Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Records Center Institute of Nuclear Power Operations Suite 1500 i 1100 Circle 75 Parkway Atlanta, Georgia 30339 NRC Inspector, Sequoyah i

f MFICIAL col'Y 1983-TVA SOTH ANNIVERSARY - ---

An Equal opportunity Employer b no