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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w 4-P'W TENN ESSEE -VALLEY AUTHORITY

- CH ATTANOOGA, TENNESSEE 37401

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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'

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Docket Nos. 50-327 Tennessee Valley Authority'

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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 requested to specifically address why the.TTD feature was desirable for power j

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 50 percent is prudent. :The feature.is primarily de:Igned to offset steam 4

l generator. level oscillations'below approximately 30 percent-power induced'by Llevel ~ control ' valve :and bypass-level control valve evolutions; however, the 4

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 1d

does not

Utilize the~P-8l interlock.in any manner. The' generic TTD design (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

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as the' input representing reactor power.

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

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(615) 843-7470.

l Very truly yours, P

TENNESSEE VALLEY AUTHORITY l

i M

E. G.

allace, Manager Nuclear Licensing and Regulatory Affairs cc: See page 2

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4003140264 900509 PDR ADOCK 05000327

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PDC An Equal opportunity Employer o q;

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

g cc: Ms. S. C.. Black. Assist' ant Director

.for Projects.

.TVA; Projects Division <

U.S. NuclearERegulatory Commission

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One H51te' Flint, North j

11555 Rockville Pike

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Rockville, Maryland 120852-

'NRCEResident Inspector

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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

101 Harletta Street, NW, Suite 2900

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Atlanta, Georgia' 130323 i

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