ML19267A288

LER 78-036/03L-0 on 781129:1 of 2 Engines Which Drive a Single Emergency Generator Failed to Start & Failed to Declutch from Generator After Failing to Start.No Cause Identified.Subsequent Tests Unable to Repeat Failure

ML19267A288
Person / Time
Site:	Fort Saint Vrain
Issue date:	12/28/1978
From:	Gahm J PUBLIC SERVICE CO. OF COLORADO
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19263A922	List: ML19267A287 ML19267A288
References
LER-78-036-03L, LER-78-36-3L, NUDOCS 7901030227
Download: ML19267A288 (3)

Text

LICENSEE EVENT REPORT

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EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h o 2 l One engine of the two driving a single emergency eenerator failed to start when re- l o 3 l quired and failed to declutch from the generator af ter failing to start. This combina- l 0 4 l tion of failures rendered the generator inoperable contrary to LCO 4.6.1. The generator l o s l is considered to have been inoperable for two days following completion of last sur- l o e l veillance tes t which is allowable by LCO 4.6.1. l 017 l l

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CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h i O lNo cause for the failure to start or failure to declutch has been identified. Subse- 1 i i lquent tests have been unable to repeat failure to start or failure to declutch. No I

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REPORI DATE: December 28, 1978 REPORTABLE OCCURRENCE 78-36 ISSUE 0 .

OCCURRENCE DATE: November 29, 1978 Page 1 of 2 FORT ST. VRAIN NUCLEAR GENERATING STATION PUBLIC SERVICE COMPANY OF COLORADO P. O. BOX 361 PLATTEVILLE, COLORADO 80651 REPORT No. 50-267/78-36/03-L-0 FJial IDENIIFICATION OF OCCURRENCE 1 On November 29,1978, the 1B emergency generator engine "C" f ailed to de-clutch after the engine failed to start. This event constitutes operation in a degraded mode and is reportable in accordance with Fort St. Vrain Tech-nical Specification AC 7.5.2(b)2.

EVENT DESCRIPTION:

On Noverber 29, 1978, the reactor was manually scrammed because of an upset in the helium circulator buffer helium system. At the time of the scram the two emergency generator sets received start signals automatically. The 1A generator set operated as it should, but one engine ("C") of generator set 1B failed to start. The generator set came up to speed on the single operating engine and would have been available for use if required. However, after the "C" engine failed to start it should have declutched from the generator in order to remove the drag from the operating engine. The operator received a fail to start alarm and, upon inspection, found that the engine had not de-clutched. Since there was no interruption of electrical yower to the plant, neither generator set was loaded af ter the scram. Both g enerator sets were shutdown. The "C" engine was manually declutched and further investigation was initiated.

Failure of the "C" engine to start followed by failure to declutch is con-sidered to have rendered the emergency generator set inoperable, and it must be assumed that it had been inoperable since the completion of the surveil-lance test on *.he generator set two days pr1or to the event. Fort S t. Vrain Technical Spec 1*1 cation LCO 4.6.1 requires that both emergency generator sets be operable while at power, and the reactor had been at power since completion of the surveillance test. However, LCO 4.6.1 allows one generator set to be inoperable for up to seven days per month and the only time during November when both generator sets were not operable was the period from completion of the surveillance test on November 27, 1978, u:itil "C" engine was manually declutched on November 29, 1978. This event constitutes operation in a de-graded mode allowable by the LCO.

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REPORTABLE OCCURRENCE 78-36 ISSUE 0 Page 2 of 2 CAUSE DES CRIPTION:

No cause has been found for the failure of "C" engine to start or for the failure to declutch. Tests completed since the event have verified that the

.angine will start when required and that the engine will declutch automatically if it does not start.

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CORRECTIVE ACTION:

The failure was apparently an isolated incident and no corrective action is planned or required other than continued surveillance testing.

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Prepared by: Hl /hL . w ,s ,A Rich'urd R. Frost y Technical Services Technician

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s Reviewed by: , p" pdf phn W. Gahin ~

fechnical Services Supervisor Reviewed by: A Frank M. Mathie Manager, Operations Approved by: 7Mes /wr Don Warembourg f Manager, Nuclear Production