ML20042G465

Provides Addl Info Re Plant Steam Generator Low Water Level Trip Time Delay & Function of P-8 Reactor Trip Interlock,Per 900430 Telcon.Trip Time Delay Does Not Utilize P-8 Interlock in Any Manner

ML20042G465
Person / Time
Site:	Sequoyah
Issue date:	05/09/1990
From:	Wallace E TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9005140264
Download: ML20042G465 (2)

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P'W TENN ESSEE -VALLEY AUTHORITY

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- CH ATTANOOGA, TENNESSEE 37401

SN 157B Lookout P1 ace O MAY 091990 1 LU;S.Nuclaar' Regulatory. Commission J

$h ATIN:. Document Control Desk Washington,-D.C. 205554

. Gentlemen:

• T"

-Inrthe Matter of'

) Docket Nos. 50-327 Tennessee Valley Authority' ) 50-328 SEQUOYAH' NUCLEAR PLANT'(SQN) - STEAM GENERATOR LOW WATER LEVEL TRIP TIME -f DELAY (TTD) - ADDITIONAL INFORMATION 1

During an ' Aprll.: 30,1990, teleohone conference call with NRC, TVA was j requested to specifically address why the.TTD feature was desirable for power 4, .

levels up to 50_ percent; and~what function the P-8 reactor trip--interlock .

. performed in.the ,SQN TTD design.- d TVA believes that application of the TTD feature to power levels as high as 4 50 percent is prudent. :The feature.is primarily de:Igned to offset steam -

l generator. level oscillations'below approximately 30 percent-power induced'by  ;

4 ,

Llevel ~ control ' valve :and bypass-level control valve evolutions; however, the starting:of the second main,feedwater, pump at.opproximately 45-percent power i may also: induce steam generator:< level' oscillations.

4 Concerning ~ the function of the P-3 reactor tr!p interlock, the SQN .TTD feature 1

does not

Utilize the~P-8l interlock.in any manner. The' generic TTD design d (described in Westinghouse: Electric-Corporation'WCAP-11325-P-A (Revision 1),

" Steam Generator low Water Level Pcotection System Modifications to Reduce lFeedwater-Related Trips," used P-8 as an indication of reactor power. .In the-lSQN TTD-design', reactor coolant system loop; differential temperature is used [

as the' input representing reactor power. q

.I

, Please direct questions:concerning this issue to Russell R. Thomp.on at )

(615) 843-7470. l

. Very truly yours, P TENNESSEE VALLEY AUTHORITY l i

E. G. allace,MManager Nuclear Licensing and Regulatory Affairs cc: See page 2 [

4003140264 900509 PDR ADOCK 05000327 -l g '

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PDC An Equal opportunity Employer .

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2-MAY 09 M U.S. Nuclear Re'ulatory' g Commission.

<. cc: Ms. S. C.. Black . Assist' ant Director ,

.for Projects.

.,, .TVA; Projects Division < ~

U.S. NuclearERegulatory Commission

, One H51te' Flint, North j ~

11555 Rockville Pike Rockville, Maryland 120852-

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'NRCEResident Inspector  ?

, Sequoyah Nuclear. Plant '

-2600_Igou Ferry Road' Soddy-Daisy, Tennessee- 37379

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Mr. B. A. Wilson, Assistant Director l for Ir<spection Programs  !

TVA Projects Division l U.S. Wuclear'. Regulatory Commission Region.II' . . r

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101 Harletta Street, NW, Suite 2900 Atlanta, Georgia' 130323 i

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