ML20085M725

AO 50-267/75/15:on 750709,during Repair of Minor Oil Leak on Gasoline Engine of Emergency Fire Pump Inlet Manifold, Piping Found Cracked.Caused by Component Failure.New Manifold Ordered & Defective Casting Replaced

ML20085M725
Person / Time
Site:	Fort Saint Vrain
Issue date:	07/18/1975
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
ML20085M720	List: ML20085M718 ML20085M725
References
AO-50-267-75-15, NUDOCS 8311090185
Download: ML20085M725 (4)

Text

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.. O ss C) public service company e conomito P. O. Box 361, Platteville, Colorado 80651 July'18, 1975 g to

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Mr. E. Morris Howard, Director e j.; ,',. 9,%y Nuclear Regulatory Commission 'sl 9,

Region IV p/-m#

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Office of Inspection and Enforcement '

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Suite 1000 Arlington, Texas 76012 Ref: Facility Operating License No. DPR-34 Docket No. 50-267

Dear Mr. Howard:

Enclosed please find a copy of Abnormal Occurrence Report No. 50-267/75/15, Final, submitted per the requirements of the Technical Specifications.

Very truly yours,

,.A.1% 2 .<' Y Frederic E. Swart Superintendent Nuclear Production Fort St. Vrain Nuclear Generating Station

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.. - o o July 18, 1975 ABNORMAL OCCURRENCE l

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l OCCURRENCE DATE: July 9. 1975 ll 1

FORT ST. VRAIN NUCLEAR CENERATING SIATION l PUBLIC SERVICE COMPANY OF COLORADO P. O. BOX 361 .

' PLATTEVILLE, COLORADO 80651 REPORT NO. 50-267/75/15 Final 1 .

IDENTIFICATION OF OCCURRENCE: .

While repairing a minor-oil leak on the gasoline engine of the emergency fire pump (P-4501S) on July 9,1975, the mechanic noticed that the inlet

. manifold piping was cracked.

• This has been identified as an abnormal occurrence, as per paragraph 2.1,

• Section'.(E) of the Technical Specifications. ,

CONDITIONS PRIOR Steady State Power Routine Shutdown TO OCCURRENCE:

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

. Refueling Shutdown Routine Startup The major plant parameters at the time of the event wcre as follows:

Power PTR, O MWth ELECT, O MWe Secondary Coolant Pressure 325 -psig i Temperature 115 F .

I Flow 0 f/hr.

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Primary Coolant Pressure 0.5 psig Temperature 115 'F Core Inlet 115 'F Core Outlet Flow 32.500 f/hr.

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DESCRIPTION OF ,

OCCURRENCE:

I Curing the repair of a small oil leak, inspection of the gasoline engine on the emergency fire pump (P-4501S) found what vere thought to be a crack l on one of the inlets of the inlet / exhaust manifold. Further checking with a dye-penetrant showed that the manifold had cracks (partial circumferential).

At least four of the six cylinder inlets appear to have small cracks. The s cracks were in each case located at the junction of the air passage with the mounting flange of the cast iron manifold. -

APPARENT CAUSE OF OCCURRENCE: Design Unusual Service Cond.

Including Environm,ent

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

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Procedure' ANALYSIS OF OCCURRENCE:

The reason for the cracks in the inlet passage of the canifold has not been

identified. Three possible causes of the failure could be

1) Cyclic temperature stresses, because the one piece manifold contains . .

'six inlet ports, six exhaust ports, and cooling water passage ways.

2) Possibly the manifold was misaligned when installed.

3) Combination of vibration and size of the manifold.

The engine was, and is,, operable with these cracks. Even with further cracking the engine would be operable but at reduced power.

l CORIECTIVE ACTION:

A new manifold has been ordered and the defective casting will be replaced.

l The quarterly preventive maintenance inspection procedure will be~ revised to make a visual inspection of the manifold. A dye-penetrant check of any suspected cracks will be made during the annual preventive maintenance in-spection.

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FAILURE DATA /SIMILAR REPORTED OCCURRENCES: \

None ,

PROGRAMMATIC IMPACT:

None CODE IMPACT:

None ,

Submitted by: M. '

i H. W.11111 yap Jr.

Technical Services Supervisor Fort St. Vrain Nuclear' Generating Station Reviewed by:

,' Frank M. Mathie Superintendent, Maintenance Fort St. Vrain Nuclear Generating Station Approved by: +a . ti J.

FfedericE. Swart Superintendent, Noclear Production Fort'St. Vrain Nuclear Generating Station e

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