ML20084J159

Ro:On 730416,during Leak Rate Tests of Containment Isolation Valves,Steady Flow of Air Noticed Leaking Past Valve Disc on AO-2-1601-22.Rubber Seat Cleaned & Valve Packing Tightened

ML20084J159
Person / Time
Site:	Quad Cities
Issue date:	05/16/1973
From:	Stephenson B COMMONWEALTH EDISON CO.
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084J153	List: ML20084J159 ML20084J164
References
BBS-73-94, NUDOCS 8305120207
Download: ML20084J159 (3)

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[ .h3 ' Ouad CititL,4ctear PowerStation l Post Office Box 216 QMJ%

Cordova, lilinois 61242 Tolophone 309/654-2241  ; ,1.

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g7]g;ggv May 16, 1973 Mr. Angelo Giambusso Deputy Director for Reactor Projects Directorate of Licensing

- U. S. Atomic Energy Commission Washington, D. C. 20545 ,

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SUBJECT:

Quad-Cities Nuclear Power Station Unit //2 ,

df M[b7 Docket No. 50-265, DPP-30, Appendix A,

., Sections 4.7.A.2.1.(2)(b) and 6.6.C.2.

Dear Mr. Giambusso:

The purpose of this letter is to inform you of the details gf 'concerning an excessive leakage measurement which was made J> during a primary containment local leak rate test on the y[f Unit 2 drywell purge valves. This unusual event took

- place on April 16, 1973 while the reactor was in the cold L shutdown condition.

DESCRIPTIO1 On April 16, local leak rate tests were being performed on Unit 2 primary containment isolation valves and test-able penetrations. This test was not reauired at this t ime , however, it was scheduled when Dresden Station experienced leakage on these valves. Air-operated valves 2-1601-21, 2-1601-22,-2-1601-55 .and.2-1601-56 were placed in the closed position and the enclosed volume was pres- j surised to the - 48 psig test pressure. Prior to beginning $ g the tent, each of these valves was cycled open and closed "#

twice to . demonstrate valve operability. ]hegl Following pressurization of the volume, a pressure decay tent was run for_ one hour in order to measure the leakage.

This leakage was 99.0 SCFH, which exceeded the acceptance

-criteria of- 18.36 SCFH (5 percent Lto)' for any one pene-tration or isolation. valve.- However/ the Limiting

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O O Mr. A. Giambusso May 16, 1973 i

i Condition for Operation relating to primary containment was never exceeded since total allowable containment leakage was within specifications.

While observing the pressure decay, a steady flow of air I was noticed leaking past the lower left portion of the valve disc on AO-2-1601-22. Following the leak test, the. leaking valve was opened and maintenance personnel thoroughly cleaned the rubber seat. The valve packing was.also tightened. On April 17, the volume was again tested and the leak rate was measured at 92.8 SCFH.

Again, air was. observed to be leaking past the disc.

With the 1601-22 valve in the closed position, a clear-ance of approximately 1/32" was measured between the valve disc and the rubber seat at the spot where the air leakage had been observed. The valve was removed from service and the disc was adjusted and re-positioned with shims to center it on the rubber seat. After returning the vdve to service, it was operated twice to check oper-ability.

On April 19, a leakage test was performed on the volume and the leak rate was 6.5 SCFH. No leakage was notf ced past the disc on valve 1601-22.

INVESTIGATION AND CORPECTIVE ACTION The volume enclosed by air operated drywell purge valves 2-1601-21, 2-1601-22, 2-1601-55a and 2-1601-56 had been T sted for leakage on Ehree'~ occasions prior to April 1973 The preoperational leak rate test was performed on August 15, 1971 and the measured leakage was 6.70 SCFH.- The total isolation valve leakage during the entire preop-erational test was 82.99 SCFH, which was less than the allowable leak rate of 110.16 SCFH (30 percent Lto) for testable penetrations plus isolation valves. The drywell purge valves were again leak checked on Mav. 14, 1972 and August, 23, 1972 following minor valve repairs. The measured leakages on these two occasions were 12 3 =SCFH and 15.5'SCFH, respectively.

Following the successful leak-te.st on April 19, 1973, leakage: measurements- were made on the other Unit 2 air-operated primary containment vent and purge valves having

. valve discs similar to that of AO-2-1601-22. 'The following results were obtained:

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V Mr. A. Giambusso May 16, 1973 Volume Valves Leakage Drywell and torus A0-2-1601-23, 24 11.25 SCFH exhaust lines 60, 61, 62, 63 Torus vent lines A0-2-1601-20A, 0. 6 4 S CFH CV-2-1601-31A Torus vent lines A0-2-1601-20B, 1.91 SCFH CV-2-1601-31B These results were all within the acceptance criteria of 18.36 SCFH.

Similar leak tests were run on the Unit 1 drywell and torus vent and purge valves on May 5, 1973 with satis-factory results. The volume enclosed by A0-1-1601-21, 22, 55, and 56 had an acceptable leakare of 15.0 SC"H.

In all of the testing and inspections no deterioration of the rubber vglye seats was detected. This is the first occuMn,ce of%1s ~ type at Quad-Cities and increased surveillance is planned for these valves at approximately 6 month intervals.

Sincerely, 4 COMI'0!!WE ALTH EDISO:I COI:P Ally QUAD-CITIES :lUCIrAR e PO' DER STATION

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Superintendent BBS/lk cc: Director of Compliance, Region III Directorate of Regulatory Operations L .]