05000247/LER-1981-021-99, /99X-0:on 810829,pinhole Leak Discovered in Elbow on 2-inch Svc Water Outlet Line.Caused by Erosion of Pipe Matl.Elbow & Pipe Replaced

/99X-0:on 810829,pinhole Leak Discovered in Elbow on 2-inch Svc Water Outlet Line.Caused by Erosion of Pipe Matl.Elbow & Pipe Replaced

ML20010H753
Person / Time
Site:	Indian Point
Issue date:	09/14/1981
From:	Matthew Smith CONSOLIDATED EDISON CO. OF NEW YORK, INC.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20010H750	List: 05000247/LER-1981-021, Forwards LER 81-021/99X-0 05000247/LER-1981-021-99, /99X-0:on 810829,pinhole Leak Discovered in Elbow on 2-inch Svc Water Outlet Line.Caused by Erosion of Pipe Matl.Elbow & Pipe Replaced
References
LER-81-021-99X, LER-81-21-99X, NUDOCS 8109290261
Download: ML20010H753 (3)

LER-1981-021, /99X-0:on 810829,pinhole Leak Discovered in Elbow on 2-inch Svc Water Outlet Line.Caused by Erosion of Pipe Matl.Elbow & Pipe Replaced

Event date:
Report date:
2471981021R99 - NRC Website

text

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o l 2 l [While the unit was at cold shutdown on 8-29-81 a pin hole leak was

discovered in an elbow on the 2" service water outlet line from in j,;

g n j., ;.No. 25 Fan Cooler Motor Cooler.

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A metallurgical i,;Oi The examination indicate'd iexamination of the affected area was made.

g'the leak was caused by erosion of the pipe material adjacent to the gg,gl downstream side of the elbow.

The elbow and pioe were replaced.

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ATTACHMENT Docket No. 247 Consolidated Edison Co. of N.Y.-Inc.

LER - S1-021/ 99%/-0 Indian Point No. 2-

Description

While the unit was at cold shutdown on August 29, 1981 a pin hole leak was discovered on the 2 inch service water outlet line from No. 25-fan cooler motor cooler.

The material of the pipe was 90/10 copper nickel with a nominal wall thickness of 0.120".

The service water system contains brackish salt water at a pressure which is normally less than 100 psig.

The pin hole leak was in the pipe material in an area adjacent to the down-stream side of the elbow weld in the heat affected zone.

The elbow and a short portion of pipe was cut out.. A metallurgical examination indicated that the most probable cause of the leak was erosion.

A flow test of the motor coolers showed a fluid velocity over 10 ft./sec.

Imme'diate Corrective Action 1.

The elbow and short piece of pipe was replaced.

2.

In ordar to determine if the condition was generic to all of the 2" elbows in the motor cooler piping,a non-destruc-tive examination program was instituted.

An evaluation was first performed to identify those elbows which would be most susceptible to erosion caused by fluid velocity and turbulence and which should be inspected.

Of the total of 228 welds on the 90* elbows on the supply and return side of the motor coolers 81 were selected for radiographic exami-nation.

In addition, a mitered elbow and a flexible hose were also examined.

There were-12 indications of reduced wall thickness using the x-ray examinations.

These areas were then ultrasonically examined.

Of the 12 only 2 showed wall thicknesses below the minimtra acceptable thickness of 0.090".

These 2 welds were repaired using 90-10 copper nickel filler by means of a standard industry practice of pad welding to increase the thickness of the effected areas.

The repairs were inspected by visual and dye pentrant exami-nation., and were found to be satisfactory.'

3.

In order to reduce the velocity and therefore the erosive effect on the motor cooler elbows the normal operation of-the " vital" service water header will be modified until permanent system changes can be made to effect the same result.

The interim change will. consist of having Valve TCV 1104 secured in the locked open position.during the-normal mode of operation.

Service Water System tests during the present outage have verified that velocitv through the motor _ coolers under this mode of operations will be re-duced to acceptable values.

Since valve TCV-1104 automati-cally goes open in the accident condition this method.of-operating is not considered unsafe.

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s Long Range Corrective Action 1.

As soon as practicable after return to service from the present outage an on line test will be made of the Fan Cooler / Motor Cooler Service Water Systems.

These are ex-pected to verify data previously recorded.

2.

By the end of the next refueling outage, system modifica-tions will have been made so that valve TCV-1104 can be placed in its normally closed position during normal plant operation 3.

During the next refueling outage the 12 welds that indi-cated reduced wall thickness, including the 2 that were pad welded, will be radiographically and ultrasonically examined again to verify that their wall thicknesses are still satisfactory.

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