ML17252A767

Supplemental Report on Excessive Leakage Through Valve A03-1601-21

ML17252A767
Person / Time
Site:	Dresden
Issue date:	06/17/1975
From:	Stephenson B Commonwealth Edison Co
To:	James Keppler NRC/RGN-III
References
BBS Ltr. #376-75 50-249/1975-6-A
Download: ML17252A767 (4)

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• BBS Ltr. *#376-75 Mr. James G. Keppler, Regional Director DireC-torate of Regulatory Operations-Region IIIolJi' U. S~ Nuclear* Regulatory Commission 799 Roosevelt Road.

Glen Ellyn, Illinois 6o137

. S~:. suPPLEMENTAL REPORT ON EXCESSIVE LEAKAGE THR0UGH VALVE A03-16o1..:.;>,1.

References:

1) Drawing Number:

M-35(>"

2) Report Number:* 50-249/1975-6 Report Number:

50-249/1975-6-A Report Date:

June 17, 1975 1.i Occurrence Datei:* February 14, 1915

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• Facility: "Dresden Nuclear Power Stai;ti.on~ Morris, Illinois INTRODUCTION On.Feb~ 1£, 1975 leakage in excess of the Technical Specification limit of 5% L'OO; (29.381 scfh) was detected through isolation valve AO 3-1601-21 (report no. 50.249-1975:!-0).

~en the valve was r~ved from the*system, cracks were found in the valve seat *. The caus'e of the cracks was not lmown at that time, and the valve was sent 1D ti:ie manufacturer for further evaluation.

DESIGNATION OF APPAREm' CAUSE The.manUtacturer examiiied the valve and found that it leaked totally around the seating area when pressurized to 30 psig. The valve seat had two deep tears or cracks' about one inch long off the seating area *. Although the cracks the1118elves did not leak, they distorted the rubber seat, causing the overall leakage.

The manufacturer;;iil':(fund the rest of the seat in good condition. Because the leak-age was g~eralized, improper valve assembly was not considered a pi-obable cause; however, the manufacturer could not rule out cryogenic deterioration.

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e June 17' 1975 CORIIDYrIVE ACTION

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Since cryogenic -deterioration of the valve seat appears to be a possible*qause of the leakage, a temperature element will monitor the valve area du?_oing the nitrogen inerting process. Before the en4 of the outage, the t~perature element will be repositioned on the bottom pf the pipe to indicate1any l:i;qu.id nitrogen accumulation.

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ADM I U I STRATI VE PROC EOURE~

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SUPPLEMENTAL REPORT APPROVED

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