ML20084T534

Ro:On 721025,during Local Leak Rate Tests,Visual Insp of Valve 3-1601-22 Revealed Cracks in Rubber Seat.Cause Not Stated.All Primary Containment Rubber Seated Valves Will Be Removed & Seat to Manufacturer for Reseating

ML20084T534
Person / Time
Site:	Dresden
Issue date:	11/15/1972
From:	Worden W COMMONWEALTH EDISON CO.
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084T532	List: ML20084T534
References
NUDOCS 8306230249
Download: ML20084T534 (2)

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Commonwealth Edison Company  :

72 WEST ADAMS STREET

• C H I C A G O, ILLINOIS AMress C. ply Con POST OrflCE SOE 767 W C H IC A G O, liL lN OIS 40 69 0 Dresden Nuclear Power Station P. R. #1 ca 7,8, Q Morris, Illinois 60450 -g(,,,,"'6-

> 1 y November la, 1972 i

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Mr. A. Giambusso a Deputy Director for Reactor Projects 2 Directorate of Licensing ,

Washington, D.C. 20545

Subject:

License DpR-25, Dresden Nuclear Power Station, Unit #3, '" .

Section 6.6.C.1 of the Technical Specifications

Dear Mr. Giambusso:

This is to report a condition relating to the operation of the station, when, during local leak rate testing of primary containment rubber seated ventilation valves, the valves associated with primary containment system penetration X-126, had a leakage rate greater than that specified for a single penetration.

PROBLEM AND INVESTICATION At 1100, October 25, 1972, with the reactor at a power level of 805 MWe, local leak rate tests were being cor. ducted on the primary containment rubber seated ventilation valves. These tests are required each refueling outage, but presently are conducted on a three month frequency due to previously experienced problems with deterioration of the valves' rubber seats. On the first test of the valves associated with penetration X-126, the leakage was 129.9 scf/hr, which exceeds the Icak rate specified for a singic penetration (29.34 scf/hr). These valves were last tested on July 19, 1972 and had a leakage of 14.7 scf/hr.

Upon visual inspection of valve 3-1601-22, cracks in the rubber seat were observed. A blind flange was placed over the penetration to insure adequacy of primary containment. At 1400 hours0.0162 days <br />0.389 hours <br />0.00231 weeks <br />5.327e-4 months <br /> another test was run and the leakage was 40.75 scf/hr. Minor leakage was noted around the blind flange. This flange was tightened and the leakage was reduced to 32.28 scf/hr with no lea W e around the blind flange. The other rubber seated valves on Units 2 and 3 were all tested with satisfactory results.

l 8306230249 721214 l

PDR ADOCK 05000249 l S PM l 6494 COPY SWP REGION ' A

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' November 15, 1972 Mr. A. Gianbusso .

In the initial integrated leak rate test of the Dresden Unit #3 primary containment, which was conducted from August 22, 1970, through August 26, 1970, the total leakage Lm(48) out of the primary containment was calculated to be 0.232 weight percent of the contained air. Using the latest available leak rates, including the 32.28 scf/hr for penetration X-126, the total leakage Lm(48) from the primary containment is now 0.362 weight percent, which is well within the Technical Specification limit of 1.6 weight percent of the contained air per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

CORRECTIVE ACTION As soon as practical, all primary containment rubber seated valves similar to and including the subject valve, will be removed and sent to the manufacturer to be resented with an improved seat material. These valves will continue to be checked on a three month basis in the interim.

Sincerely, A. \\f 83? ,_-

W. P. Worden Superintendent WPW:sdb l

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