ML20086B414

AO 50-267/74-14:on 740729,engine B of Diesel Generator Set a Failed to Start.Caused by Shutdown Mechanism Tripping. Engines Will Be Modified Pending Confirmation from Caterpillar to Machine Spacer

ML20086B414
Person / Time
Site:	Fort Saint Vrain
Issue date:	08/09/1974
From:	Mathie F, Swart F PUBLIC SERVICE CO. OF COLORADO
To:
Shared Package
ML20086B380	List: ML20086B384 ML20086B401 ML20086B414 ML20086B419
References
AO-50-267-74-14, NUDOCS 8311170195
Download: ML20086B414 (3)

Text

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7Date:

o Auntg9 1974 O

A'2NOPJiAL OCCURRENCE a

FORT ST. VRAIN NUCLEAR GENERATlHG STATION PUBLIC SERVICE C010'/J:Y OF COLORADO P.O. BOX 361 PLATTEVILLE, COLOPNX) 80651 REPORT No. 50-247/74/14 Preliminary ,

4 IDENTIFICATION OF f OCCURRENCE:

Engine "B" of diesel-generation set "A" failed to start during routine surveillance, July 29, 1974.

This is considered an abnormal occurrence per section 2.1 (f) of the Technical Specifications.

CONDITIONS PRIOR '

Steady State Power Routine Shutdown To OCCURRENCE:

Hot Shutdown Routine Load Change 4

X Cold Shutdown Other (specify)

Refueling Shutdown Reactor in helium - approxitutely Routine Startup atmospheric pressure

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The major plant parameters at the time of the event were as follows:

PTR, 0 M;lth Power s e.

ELECT, O MWe Secondary Collant Pressure o peig Temperature 0 *f Flow 0 f/hr.

Primary Coolant Pressure O psig Temperature 100 *F Core Inlet 8311170195 741209 PDR ADOCK 05000267 100 *F Core Cutlet l

S PDR Flow 0 f/hr.

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• Page 2 DESCRIPTION OF OCCURRENCI::

On a mutine ntart during curvei]1ance testing, engine "B" of "A" generator was prevented from ut arting because the shutdown mechanism, actuated by lov oil pronsure or engine overspeed, had tripped.

J APPARENT CAUS2 /

OP OCCURRENCE:_ X Design _ Unusual Service Cond. - t Including Environ.

X Manufacture Component Failure Installation /Const. Other (specify) i Operator Procedure __

Tolerances in the shutdown mechanism are such that a trip, such as -

that experienced, is a finite, but improbable, occurrence.

ANALYSIS OF OCCURRENCE:

Each time an engine is shutdown, the shutdown mechanism starts ^

actuating due to low oil pressure. On a restart, the oil pressure must reach a high enough valve to reset the mechanism before the mechanism reaches the trip point.

Infrequently the mechanism travels for enough in its cycle that reset on restart does not occur before the mechanism trips.

CORRECTIVE ACTION:

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Caterpillar Co. , the engine manuf acture'r, informs us that the -

mechanism can be made to travel further in its cycle, by having a longer travel. This is accomplished by machining a spacer which governs the start

' point.

I Ey doing this the reset will always occur before the trip.

We are presently awaiting written confirmation from Caterpillar before making this modification on all four (4) engines.

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t v) t Page 3 Fall.UltC DATA / SIMII,1 AR REPORTE1) OCCURRENCI:S:

None PROGPXBfATIC IMPACT: ,l None CODE IlfPACT:

None ll W h n ffx Frank 11. liathie 8 i+ '14-Superintendent - Maintenance b d 1 -

il Approved: ,_ u < #' <.0 < t,As h /6 7 F'ederic E. Swart (

Siperintendent Nuclear Production k'

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