ML20085M618

AO 50-267/75/19:on 750825,engine a of Standby Generator a Automatically Shut Down & Declutched During Cooldown Portion of Weekly Surveillance Test.Caused by Difference in Fuel Rack Setting.Setting Changed

ML20085M618
Person / Time
Site:	Fort Saint Vrain
Issue date:	09/05/1975
From:	Hillyard H, Mathie F, Swart F PUBLIC SERVICE CO. OF COLORADO
To:	Howard E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20085M616	List: ML20085M614 ML20085M618
References
AO-50-267-75-19, NUDOCS 8311090084
Download: ML20085M618 (4)

Text

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P. O. Box 361, Platteville, Colorado 8065 cq,

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/ .R Septerber 5,1975 ter l Mr. E. Morris !!oward, Director fluclear Regulatory Cornission -

Region IV office of Inspection and Enforcement Suite 1000 Arlington, Texas 76012 Reft Facility Operating License i No. DPR-34 l

Docket !!o. 50-267

Dear Mr. lioward:

Enclosed please find a copy of Abnormal Occurrence Report 1-Jo. 50-267/75/19, Final, submitted por the requirements of the Technical Specifications.

Very truly yours, Frederic E. Sucrt

' Superintendent, liuclear Production Fort St. Vrain !!uclear .

Generating Station FES/alk cc: Mr. Angelo Ciambusso

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8311090084 751017 PDR ADOCK 05000267 .

S PDR copy SEN1' REGION s

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.O o REPORT DATE: __

September 5, 1975 ABNORMAL OCCURRENCE 75/19, Page 1 of 3 OCCURRENCE DATE:

August 25, 1975_

FORT ST. VRAIN NUCLEAR GENERATING STATION PUBLIC SERVICE COMPANY OF COLORADO P. O. BOX 361 PLATTEVILLE, COLORADO 80651 REPORT NO. 50-267/75/19 Final 4

IDENTIFICATION OF OCCURRENCE:

"A" engine of "A" standby generator automatically shutdown and declutched during the cooldown portion of a weekly surveillance test.

This, is defined as an abnormal occurrence per 2.l(f) of the Technical Specifications. .

CONDITIONS PRIdR Routine Shutdown

'IO OCCURRENCE:

Steady State Power Routine Load Change Hot Shutdown Other (specify)

X Cold Shutdown

. Refueling Shutdown .

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

RTR O MWth Power _

O hWe ELECT Pressure 275 psig Secondary Coolant Temperature 180 *P e

' Flow 9,000 #/hr.

Pressure 1.0 psig Primary Coolant I

-Temperature 123 __

_'P Core Inlet I 170 -* P Core Outlet Flow- 1 circulator at 4,000 id'M,fi/hr.

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O o 1.BNORMAL OCCURRENCE 75/19 Ppge 2 of 3 DESCRIPTION OF OCCURRENCf::

Assistant Reactor Operator had completed the two hour, 50% load test run re-quired by SR 5.6.la-W and decreased standby generator IA to no load and opened the generator breaker, which allows the engines to cool down. After about 10 minutes running idle, the standby diesel " fail-to-start" alarm alerted the operator and upon investigation the "A" engine had shut off and declutched.

I APPARENT CAUSE I OF OCCURRENCE: Design Unusual Service Cond.

Including Environ.

Manufacture Component Failure Installation /Const. X Other (specify)

Operator Adjustment

• . l Procedurc The apparent cause of the occurrence was a difference in fuel rack setting between A and B cngines of standby generator 1A.

ANALYSIS OF ,

_ OCCURRENCE:

The standby diesel generator had just satisfactorily performed the two hour, 50% load surveillance test. The' engines were idling (at rated power) with the breaker open to cool the engines when, after about 10 minutes, trip and declutching occurred. ,

InvestigationshowedthatadifferenceinfuelracksottingbetweenhandB ~

cngines existed. Low load conditions allowed the fuel rack on A engine to close which required the B engine to maintain the rated' speed of both engines.

The exhaust manifold temperature cooled to the point at which.the temperature switch is tripped. This switch causes the engine " fail-to-start" alarm if more than 30 seconds have clapsed since thq cngine start signal occurred.

Loaded conditions would not cause this alana and trip becauce IA engine would be above the switch setpoint of 180*F.

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ABNORMAL OCCURRENCE 75/19 Page 3 of 3 CORRECTIVE ACTION:

The fuel rack setting was changed such that the pressures on each engine rack are equal, when operating at rated speed, no load conditions. In addition the surveillance will be changed to include a check of the ex-haust pressure dif ferential between the two engines at " speed, no load" .

FAILURE DATA /SIMILAR REPORTED _ OCCURRENCES:

Abnormal occurrence 50-267/75/8, 50-267/75/12, and 50-267/75/13 involved failures of the same equipment but are not related to this occurrence.

PROGRAMMATIC IMPACT:

None CODE IMPACT:

None -

Submitted By: 4_ ,

Ilarvey W.gllyard, fr.

Technical Services Supervisor Reviewed By: 9') d Frank M. Mathic Superin*.endent, Mai'ntenance Approved By: .1u u - WW

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Fr Swart S6perintendent, Nuclear Production-l I d I.

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