ML20132F681

Forwards Request for Exemption from 10CFR50,App J Requirement to Leak Test Mechanical Penetrations,For Ice Condenser Refrigeration Sys,Using Air or N as Test Medium Across Valve Sealing Surface.Fee Paid

ML20132F681
Person / Time
Site:	Mcguire, McGuire
Issue date:	09/24/1985
From:	Tucker H DUKE POWER CO.
To:	Adensam E, Harold Denton Office of Nuclear Reactor Regulation
References
TAC-59796, TAC-59797, TAC-60601, TAC-60602, NUDOCS 8510010389
Download: ML20132F681 (4)

Text

e DuxE POWER COMPANY P.O. BOX 3318D IULL B. TUCKER CHARLOTTE N.,C. 28242 ver.s emessnesev TELEPlf0NE

==^=*=== 904) oW531 September 24, 1985 Mr. Harold R. Denton, Director Office of Nuclear _ Reactor Regulation U. S. Nuclear Regulatory Commission-Washington, D. C. 20555 Attention: Ms. E. G. Adensam, Chief Licensing Branch No. 4

Subject:

McGuire Nuclear Station Docket Nos. 50-369 and 50-370 Request for Exemption from 10 CFR 50 Appendix J Requirement

Dear Mr. Denton:

Attached is a Request for Exemption from the 10 CFR 50 Appendix J Requirement to leak rate test mechanical penetrations using air or nitrogen as the test medium across the valve sealing surface. This Request for Exemption pertains to two penetrations for the Ice Condenser Refrigeration System where it is otherwise necessary to drain approximately 200 gallons of glycol. An outline of the procedure is included in the request.

The proposal would allow an alternative means of testing whereby glycol would

.be used as the pressurization medium. If the acceptance criterion (zero leakage) is not met, the penetration will be fully ~ drained and tested in accordance with Appendix J.

Review and approval is requested by February 1, 1986 to support the current test cycle. Pursuant to 10 CFR 170.21, a check for $150.00 is enclosed.

Please feel f ree to contact us if you require any additional information. -

Very truly yours, N' -

4 JA Hal B. Tucker JBD/hrp -

Attachment ec: Dr. J. Nelson Grace, Regional Administrator Mr. W. T. Orders U. S. Nuclear Regulatory Commission NRC Resident Inspector Region 11 101 Marietta Street, NW, Suite 2900 McGuire Nucle r Station [(N Atlanta, Georgia 30323 J g gl0g i 8510010389 850924 PDR 1 P ADOCK 05000369 # 3 1

PDR i

F Reauest for Eremotion from 10CFR50 Anoendir J Reauirement 10CFR50 Appendix J III'C.2(a) requires mechanical penetrations to be leak rate tested using air or nitrogen as the test medium across the valve sealing surface. An exemption is requested from this requirement for penetration numbers M-372 and M-373. The local leakage test will.be performed without draining the glycol from the seats of the diaphram valves in these penetrations.

Attachment A depicts the arrangement of these penetrations.

McGuire utilizes an ice condenser to surpress the peak accident pressure in the reactor containment building.. The ice condenser is refrigerated by recirculating a 50% - 50% mixture of ethylene glycol and water through a series of air handling units located

- inside the containment building and chillers units located in the auxiliary building. . Typically, draining, testing and refilling the system requires 24 to 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> of downtime for the ice condenser refrigeration system. This extended downtime potentially diminishes the amount of ice in the baskets.

D 31ning the glycol consumes a significant number of manhours and creates toxic waste which has to-be disposed.

As an alternative .to draining the ~200 gallons of glycol necessary to perform this test in accordance with Appendix J, the following procedure for testing these penetrations is proposed.

Penetration M-373 would be drained through NF-1173 and NF-960.

NF-229 (a duo check valve) would be local leak tested with air on both sid e s .' NF-228A would then be tested with air as the

• pressurization medium and glycol on its seats. The system high point vent, NF-1150, would serve as the vent valve for-NF-228A.

Similarly, M-372 would be tested without completely draining the glycol. NF-233B would be tested by pressurizing through NF-957 utilizing NF-236 as the test vent. NF-234A would be pressurized through NF-957 utilizing NF-1150 as the test vent.

NF-228A, NF-233B and NF-234A are diaphragm valves which have an excellent . history of leak tightness. This characteristic is primarily due to the resiliency of the rubber diaphragm. If a rupture of the diaphragm were to occur, it would be evident via leakage around the valve stem due to the static pressure maintained on the glycol system.

A- bench test was performed at McGuire to corrolate the leakage rate of air and the Glycol / Water mixture. A test stand was fabricated using a metering- valve to achieve a repeatable leakage area. The upstream side was pressurized to 15 psig, the downstream side discharged to atmosphere and temperature was held

. const ant at 75 degrees F. The following results were obtained:  ;

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AIR LEAK WATER / GLYCOL RATE (SCCM) LEAK ~ RATE (SCCM) 500 15 1000 28 1500 47 These results infer a 1 to 31 glycol to air leakage ratio with a .994 corrolation coefficient.. This ratio will be different at different temperatures due to changes in kinematic viscosity.

The leakage rate acceptance criteria that would be imposed on these diaphragm valves would be zero inlicated leakage (not including instrument error).

If the leak rate is greater than zero, the penetration will be fully drained and the valves leak tested in accordance with Appendix J. Performing the local leakage rate test on these penetrations without fully draining-them will not compromise containment integrity.

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