ML17252A861

Letter Concerning a 05/16/1973 Occurrence Where a Leak Was Observed at a Weld on a 3/4 Inch Pipe-To-Socket Weld Branch Connection Between Valve S-47 and Line No. 355 of the Residual Heat Removal System - Indian Point Unit No. 2

ML17252A861
Person / Time
Site:	Indian Point
Issue date:	05/25/1973
From:	Caldwell W Consolidated Edison Co of New York
To:	O'Leary J US Atomic Energy Commission (AEC)
References
Download: ML17252A861 (2)

Text

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' William E. Caldwe*** .

• . :11;cii* President

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Consolidated Edison Company of New York, Inc.

4 Irving Place. New York, NY 10003 Telephone (212) 460-5181 May 25, 1973 Re Indian Point Unit No. 2 AEC Docket No. 50-247 ~..;..;.....

Facility Operating License DBR-26 Mr. John F. O'Leary, Director Directorate of Licensing U. S. Atomic Energy Commission Washington, D. C. 20545 Dear Mr. O'Leary In accordance with the requirements of Technical Speciftcation 6.6.1.B we informed you on May 16, 1973 by telegram of Abnormal Occurrence No. 3-2-4 which was identified on May 15, 1973 at 1300 Hrs. During the course of a routine plant status inspection, a leak was observed~' ..

at a weld og_a..3/4 inch pipe-to-socket weld branch connection between valve S-47 and line No. 355 .of the Residual Heat Removal System. (The connection is located on the discharge side of the Residual Heat Removal Exchangers, upstream of the check valve 838A).

Examination of the leak indicated that it was caused by a fine crack approximately 3/4" long between the weld fillet *and the half coupling socket. The location of the crack suggested that a defect internal to the weld propagated to the surface allowing leakage.

Folld>wing the discovery of the leak, the circumstances preceding the leak.age were investigated. Ex:amination of records disclosed that Vent Assembly S-47 was ~ew.:orked on October 4 and 5, 1972 to replace an thinwall nipple between'the socket and valve. This rew.:ork included removal of the entire vent valve assembly. .A new 3/4 inch socket weld half coupling and shop fabricated assembly was welded to line 355.

Both Con Edison and WEDCO Quality Control personnel inspected the welgs and verified the absence of defects. The assembly was then hydro-statically ~ested to verify that the welds were sound. '

Previous analysis as well as recent verification of such analysis indicate that stresses resulting from vibration are insufficient to cause cracking.*

Therefore, it is unlikely that vibration or other stresses caused the May 15, 1973 leakage. Despite that fact, the vent assem~ly was shortened by two inches during the recent repair. This action will reduce the possibility of *vibration induced stresses in the weld.

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John F. O'Leary May 25, 1973 Re Indian Point Unit No. 2 AEC Docket No. 50-247 Facility Operating License DPR-26 In addition to shortening the pipe nipple on Mai 16, 1973, the leaking connection was ground out, and the assembly was rewelded in accordance with the appropriate procedures. The welds were then inspected by dye penetrant and subjected to hydrostatic testing to verif'y their structural integrity.

The leakage resulting from this abnormal occurrence is readily detectable and is well within the makeup capabilities of the plant C.hemical and Volume Control System without incurring adverse conseque~ces to the health and safety of facility personnel or to the public. Furthermore, at the time of the occurrence the reactor was in a cold shutdown condition at atmospheric pressure and the leakage was not radioactive. For these reasons, there are no safety implications to the occurrence.

Having reviewed the circumstances of the abnormal occurrence the Con Edison Nuclear Facilities Safety Committee concurs that the occurrence does not represent a significant hazards consideration.

Very truly yours William E. Caldwell, Jr.

EAO/ds Vice President Copy to James P. O'Reilly (AEC)

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