ML20046B890

Revises Info Provided in TVA 930223 Response to GL 88-14 Re Design of Drywell Control Air (DCA) Sys & Components Supplied by DCA Sys.Rev Commited to on 930122,in Response to Deviation Noted in Listed Insp Rept

ML20046B890
Person / Time
Site:	Browns Ferry
Issue date:	07/30/1993
From:	Salas P TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-88-14, NUDOCS 9308060377
Download: ML20046B890 (2)

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wneme vaney AutnemqMt OHee Box 2000. Decatut Alabama 3%09 l

JUL 3 01993

!3 U.S Nuclear Regulatory Commission

.i ATTN:

Document Control Desk i

Washington, D.C.

20555 l

Gentlemen:

1 In the Matter Of

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Docket Nos. 50-259 Tennessee Valley Authority

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50-260 50-296 j

i BROWNS FERRY NUCLEAR PLANT (BFN) - UNITS 1, 2 AND 3 -

l SUPPLEMENTAL RESPONSE TO GENERIC LETTER (GL) SS-14, i

INSTRUMENT AIR SUPPLY SYSTEM PROBLEMS AFFECTING BAFETY-RELATED EQUIPMENT l

The purpose of this letter is to revise information provided.

t in TVA's February.23, 1989, GL 88-14 response relative to the design of the drywell control air (DCA) system and components supplied by'the DCA system.

TVA committed to this revision on January 22, 1993, in response to a Notice of Deviation identified in Inspection Report 92-41'.

In the referenced letter, TVA stated'that the DCA system was i

designed to provide air with a moisture dew point of 30 degrees F.

This dew point.is not consistent with vendor information or the system capability.- Specifically, the-f vendor states that the normal heat exchanger.(dryer) cell I

temperature is maintained between 34 degrees F and' 38 degrees F by means of thermostat that controls the

'I operation of the mechanical refrigeration system.

Thus, the DCA system is designed to maintain a nominal 35 degrees F dew point at line pressure.

l Secondly,~TVA specified a minus 40 degrees-F moisture dew point for the main-steam isolation valves (MSIVs)'and the' main steam relief valves (MSRVs). which'was. consistent with-the vendor information at the time.

However, this requirement-for the MSRVs has since been deleted from vendor i

documents and-replaced with qualitative requirements (i.e.,

J provide oil-free,. moisture-free air). - The~vendorJinformation I- [

for MSIVs has also been revised'to. indicate a plus

.35 degrees F moisture' dew point requirement.

f)O ceocy 3ty 9308060377 9307O 3

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U.S. Nuclear Regulatory Commission JUL 3 01933 As a result, this letter revises information pertaining to the DCA system.

Specifically, the changes include a nominal DCA system dew point of 35 degrees F at line pressure, a new air quality requirement of plus 35 degrees F dew point for the MSIVs, and no quantitative dew point for the MSRVs.

If you have any questions, please telephone me at (205) 729-2636.

Sincerely, J. -d l,l p

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,-i ro Sal:tr Manager of,ite Licensing cc:

Mr. R. V.

Crlenjak, Project Chief U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 NRC Resident Inspector Browns Ferry Nuclear Plant Route 12, Box 637 Athens, Alabama 35611 Mr. Thierry M. Ross, Project Manager U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852

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