ML20084B074

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Discusses AO 3-2-4 Re Leak Observed at Weld on 3/4-inch pipe-to-socket Weld Branch Connection Between Valve S-47 & RHR Sys Line 355 on 730515.New Socket Weld Half Coupling & Shop Fabricated Assembly Welded
ML20084B074
Person / Time
Site: Indian Point Entergy icon.png
Issue date: 05/25/1973
From: Caldwell W
CONSOLIDATED EDISON CO. OF NEW YORK, INC.
To: Oleary J
US ATOMIC ENERGY COMMISSION (AEC)
References
NUDOCS 8304060098
Download: ML20084B074 (2)


Text

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May 25, 1973 Re Indian Point Unit Ilo. 2 AEC Docket No. 50-247 Facility Operating License DPR-26 Mr. John F. O' Leary, Director Directorate of Licensing U. S. Atomic Energy Commission Washington, D. C. 20545

- e Dear Mr. O' Leary

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In accordance with the requirements of Technical Specification 6.6.1.B

~d h-/ we informed you on May 16, 1973 by telegram of Abnormal occurrence No. 3-2-4 uhich uas identified on May 15, 1973 at 1300 Hrs. During b ([; the course of a routine p2 ant status inspection, a leak was observed c

at a weld on a 3/4 inch pipe-to-socket weld branch connection between

]'/i 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

/ U, Removal Exchangers, upstream of the check valve 838A).

-a r b, Examination of the leak indicated that it was caused by a fine crack r (g f

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approximately 3/4" long between the weld fillet and the half coupling cocket. The location of the crack suggested that a defect internal to

[ [M the weld propagated to the surface alleving leakage.

1I Following the discovery of the leak, the circumstances preceding the Icakage were investigated. Examination of records disclosed that Vent Assembly S-47 was reworked on October 4 and 5, 1972 to replace an thinwall nipple bet. ween the socket and valve. This rework 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 WEDC0 Quality Control personnel inspected the welds and verified the absence of defects. The assembly was then hydro-statically tested to verify that the welds were sound.

FYevious analysis as well as recent verification of such analysis indicate that stresses resulting frem vibration are insufficient to cause cracking.

The refore , it is unlikely that vibration or other stresses caused the May 15, 1973 leakage. Despite that fact, the vent assembly was shortened by two inches ducing the recent repair. This action will reduce the possibility of vibration induced stresses in the weld.

8304060098 730525 PDR ADOCK 05000247 S PDR

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John P. O' Leary ,2- May 25, 1973 Re Indian Point Unit ITo. 2 AEC Docket No. 50-247 Facility Operating License DPR-26 i

In addition to shortening the pipe nipple on May 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 verify their structural integrity.

, The leakage resulting from this abnormal occurrence is readily detectable and is well within the makeup capabilities of the plant Chemical had Volume Control System without incurring adverse consequences 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 con'ition 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 liuclear Facilities Eafety Committee concurs that the occurrence does not represent a significant hazards consideration.

Very truly yours g/ky\ kc N William E. Caldwell, Jr.

EA0/ds Vice President I

Copy to James P. O'Reilly (AEC) l i

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