ML20085L651

AO 50-267/75/8:on 750224,diesel Engine B of Standby Generator a Failed to Function Properly During Weekly Test. Caused by Defective Temp Thermocouple.New Thermocouple Installed & Preventive Maint Program Instigated

ML20085L651
Person / Time
Site:	Fort Saint Vrain
Issue date:	03/07/1975
From:	Brey H PUBLIC SERVICE CO. OF COLORADO
To:	Howard E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
AO-50-267-75-8, NUDOCS 8311020212
Download: ML20085L651 (9)

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n o U V pubile service company ore celerade P. O. Box 361, Platteville, Colorado 80651

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I:EPORT DATE: March 4 u 1975,_ ABN0!U4AL OCCURRENCP.

OCCURKENCE DATE: Februa ry 24' 1975 ,

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FORT ST. VRAIN NUCLI%R GENERATING STATION - . .. ,

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PUBLIC SI:RVICE COMPANY OF COLORADO ,

P. O. l'OX 361 d i L .! .' .-

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.--6.4% s REPORT No. 50-267/75/8 .

Final C l IDENTIFICATION OF . .

OCCURRENCE:

On February 24,1975, "B" diesel engine of "A" standby generator failed to function properly during a veckly surveillance test. The engine started, ran for approx-imately 20 seconds, then shut down.

This is defined as an Abnormal occurrence as per definition 2.1.f) of the Technical Specifica<_fon.

CONDITIONS PRIOR tu uccusau.cr.: , steady State Poewr- , Routine Shutdown

, Hot Shutdown Routine Load Change X Cold Shutdown Other (specify)

Refueling Shutdown Routine Startup- .

The major plant parameters at the time of .the event were as fo))ows:

Power Rtr. O MWth Elect. O MWe Secondary Coolant Pressure 260 psig ,

Temperature 68 'F

. Flow 18,000 ~ #/hr. '

'p d Primary Coolant Pressure Atmospheric 'psig Temperature 100 ' 'F' Inlet. M i I- 100 #F Outlet _ i t

Flow 0 #/hr.

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DESCRIPTION OF

.O..C_CURR_ ENC E :_ _ _ _

During SI; 5.6.1 a-w, weekly test ing of the it andby d iesel generating units, l engine B of A generator, started, ran for approximat ely 20 seconds, then shut down and declutched. A second, immediate attempt to start the engine was unsuccessful.

Exhaust temperature indication for li engine showed no increase during the 20 second run.

APPARENT CAUSE OF OCCURRENCE: Design ,

_ _ Unusual Service Cond.

Including Environ.

_ Manufacture _X _

_ Component Failure

_ Installation /Const. ,,_ _ __ Other (specify)

Operator _ __ _ _ , _ _ _ _ _ _ , , _

Procedure _ ____

The exhaust temperature thermocouple had failed, and therefore showed no tempera ture increase. The control system saw this as a failure of the engine to start, and therefore, shut the engine down and declutched it, en prouane A -nging re- g-7ggi g 2 : pperedly g2:2 inn , i ANALYSIS OF '

.O._C_ .CURRESC E :

At tempting to run S.R. 5.6.1-a-w, "B" engine on the "A" diesel-genera tor unit shut down after 20 seconds. Electrical inspection revealed that the exhaust temperature thercocouple was defective. ~

These exhaust temperature thereccouples cust show high temperature in the exhaust system for a "Go" in the process of starting the units. However, the thermocouple was not open but failed to produce the necessary millivolt output to drop out the tcaperature relay, which resulted in a declutch and trip of the "B" engine.

All alarms associated with the trip operated norrdilly.

CORRECTIVE ACTION:

PTR 2-350 issued. 'A new exhaust temperature thermocouple was installed, and a program initiated on the preventive maintenance program to change out all thermocouples on the diesel-generator units on an annual basis.

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Fall.URE DATA /

SIMILIAR REPORTED OCCURI:ENCES:

None. Other thermocouples have becu changed in the pant, but because of suspected deterioration, not complete failure.

PROGRABIATIC I?1 PACT:

None CODE IMI'ACT:

I None Recommended: Approved:

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._ V ' ' M&. G . .St'J.1NWJQ Frederic E. Swart Frank M. 'fathic Superintendent-Maintenance Superintcudent Nuclear Produetion Fort St. Vrnin Nuclear Public Service Company of Colorado Cencrating Station e

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Thoned to 1,ois-Grico, Extension 7750, 2/24/75, at _y>, .

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E. Morris Howard, Director U. S. Nucicar Regulatory Commission '

Office of Inspection & Enforecaent

-Region IV 611 Ryan Plaza Drive .

Suite 1000 Arlington, Texas 76012 -

On 2/24/75, while running the veckly. surveillance tests on the emergency diesel generators, "B" engine of the "A" diesel-generator set failed to operate normally due to.a faulty exhaust temperature thermocouple.

Frederic E. Swart Supt. Nucicar Product.icn 3

Fort St. Vrain Nuclear Gc.4 crating Station i -

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