ML20101F255

Suppl 1 to Application for Amend to License NPF-86, Consisting of License Amend Request 92-01,revising TS Re RTD Bypass Sys Elimination

ML20101F255
Person / Time
Site:	Seabrook
Issue date:	06/19/1992
From:	Drawbridge B PUBLIC SERVICE CO. OF NEW HAMPSHIRE
To:
Shared Package
ML20101F241	List: ML20101F238 ML20101F255 ML20101F284
References
NYN-92081, NUDOCS 9206240351
Download: ML20101F255 (6)

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j_. ,f New llampshire Yankee June 10, 1992 l

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l' ENCL,OSURE 2 TG NYN 42041 t

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.- l SEABROOK STATION UNIT 1 New Hampshire Yankee Facility Operating License-NPF 86 Docket No. 50-443 Supplement 1 to '.icense Amendment Request No. 92-01 RTD Bypass System . Elimination This License Amendment Request la submitted by New Hampshiro Yankee pursuant to 10CFR50.90. The following information is enclosed in support of this License Amendment Request:

.Section I - Introduction and Description of Proposed Changes

.Section II -

Markup of Proposed Changes Section ill -

Retype of Proposed Changes

.Section IV -

Safety Evaluation of Proposed Changes

.Section V - Determination of Significant Hazards for Proposed Changes

.Section VI - Proposed Schedule for License Amendment issuance and Effectiveness

. Section Vl! -

Environmental impact Assessment

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Sworn and Subscribed , ,/

to before me this '

/'7f/1 dsy of (dn = c - , if)9;l /e' V, & 7, /r G cs fMA / ,i. b_ f / h(c[f A V sruce L. Drawbridgb J Notary Public Executive Director Ruc!cardroduction l i

m orf/ A. D W . Dico, f : ten Put!'c l My Ccmm:40a rnpitc5 oct:,xt a 1995

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1. Int roduct ion and Descr ip' ton of pr oposed Chn.imentjup.plement 1 t o hieense Amendinent Request q ,.01 A. Introdurtion The purpose of Supplement I to License Amendment Request 9?-01 is to pr opose changes to the Seabrook St a t ion Technical Specif ications a ssot iated with a plant design change (DCR 90-03) that will eliminate the Resistance Temperature Detector (RTD) Bypash Syst ern which is cut t ent ly ut.ed f or the measurement of narr ow range Reactor Coolant System (RCS) hot leg and cold leg temperatures. The design change will remove the RTD Eypass, Systen piping and install new thetmevell tounted fast response RTDs in the hot leg and cold leg piping. The replace nent RTD/ thetmowell combinat ion meet s the f unctional ard qualification requirements of the existing RTDs mounted in the bypa s s pi%.ig. Additional instrumentation is added to pr ocess and average the new hot leg temperature input s. The colo leg and average hot -

leg temperature signals are input t o the existing reactor protection and '

reactor contro? , stems. Changes in the Westinghouse methodology ior treating hot a .. cold leg streaming, technical differences in the d

instrumentation, and allowance for operation with one hot leg RTD inoperable have resulted in a chango in instrumentatloa uncertainties. The proposed Technical Specification c hanges ref lect these differences in the instrumentation uncertainties associated with the new temperature measurement system and delete requirements f or verification of RTD bypas, loop flow.

Additionally, the pt oposed Technical Specification changes modif y the requirements f or the perf ormance of a precision heat balance which is used to determine RCS flow rate and to normalize t he RCS flow instrumentation.

The curront Technical Specifica, ion requirement s specif y that t b precision heat balance must be performed prior to opecation above 75% of rated thermal power after each fuel loading. Wes t inghet.se ha s reconct. ended tha t the precision heat balanca be performed abo"e 902 of rated aermal power t o minimize measut ement uncert ainties that are exacerbated a - lowet power levels. New Hampshire Yankee is, therefore, proposing a change to its Technical Specifications to requit? that the precision heat balance for determination of RCS flou rate be perf ormed prior to exceeding 95% of rated thermal power.

New Hampshire Yankee has also proposed to increase the Reactor Coolant System flow rate requirement of Technical Specification Limiting Condition for Operation (LCO) 3.2.5 from the current value of 391.000 gpm to a new value of 392,000 gpm to reflect the increase in flow mee.surement encertainty as documented in WCAp-13101 The proposed 2.41 flow measurement uncert ainty value includes an additional penalt y of 0.11 flow to account f or uudetected feedwater venturi t,uling as stat ed in the Bases for Technical Specification 3/4.2.5. /

The elimination of the RTD Bypass Sys;em has been implement ed by numerous licensees with Westinghouse Fuclear Steam Supply Systems. New Hampshire Yankee is aware of the follou ng licensees which have eliminated the RTD Eypass System:

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Duke Power Company (Catawba 1/2, McGuire 1/2)

Duquesne Light Company (Beaver Valley 1/2)

Florida Power & Light Company (Tutkey Point 3/4) 11ouston Lighting & Power Company (South Texas Project 1/2)

New York Power Authority (Indian Point 3)

Tennessee Valley Authority (Sequoyah 1/2)

Volf Creek Nuclear Operating Corporatien (Wolf Creek)

Northeast Utilities (Millstone 3)

Carolina Power & Light (H.B. Robinson)

South Carolina Electric & Gas (V.C. Sutume r )

Alabama Power Company (Farley 1. Farley 2 scheduled for Spring 92)

Georgia Power Cone ty (Vogtle 1 Vogtle 2 scheduled for Spring 9?)

Westinghouse has prepared a licensing report for N!!Y in support of the elimination of the RTD Bypass System at Seabrook Station. The Westinghouse -

licenalng report WCAP-13181, *RTD Bypa ss Elf mination Licensing Repot t for Seabrook Noclear Station * (Proprietary) is enclosed in Section VIII.

Yankee Atomic Electric Company (YAEC) has also evaluated the RTD Bypass Syster .11mination rela tive t o cont ainment tosponse, steam Jenerator Tube Rupture and Baron Dilution events. The YAEC evaluation conclusions and documentatic.) are discussed in Section V.

B. Description of Proposed Channes License Amendment Request 92-01 and Supplement I thereto propose changes to the following Technical Specificati'ns:

1. Table 2.2-1, " REACTOR TRIP SYSTEM INSTRUMENTATION TRIP SETPOINTS,"

Pages 2-4, 5, 7 B, and 10 Technical Specification Table 2.2-1 terms associated with instrumentation uncertainty (TA, Z, S, ellowable value, and associated notes) have been revised due to technical differences in the RTD instrumentation, dif ferences in the We stinghouse methodology -

for treating hot leg and cold leg streaming and allowance for operation with one hot leg RTD inoperable. All values have been rounded to the nearest 0.12 in accordance with the latest Westinghouse format.

The value for the K 6 term in the overpower AT trip setpoint calculation was increased (conservative direction) . K6 is a penalty term that reduces the overpower AT trip setpoint when 'Javg is above the nominal Tavg. The setpoint when operating at or below the nominal Tavg is determined by a constant., R, 4 in the overpower AT trip setpoint calculation.

The value of the K 6 term in the overpower AT trip setpoint ,

calculation was increased as stated above. The overpower AT trip is intended to limit transient overpower during Condition and 1 s overpower transients / operator errors to 1181 power. As discussed in UFSAR section 4.3.2.2f and 4.4.2.11f, limiting overpower to 1181 2

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ensures that peak f uel rod lin ct heat generation rates during such an occut:ence will not exceed the 1ineat powerfot pt evention of f uel centerline melting. The K t term of the overpower AT trip is a penalty term that teduces the trip setpoint when T,y is above the nominal 7,y . An inctease in K, 5 is thetetore a thange in the conservative direttien. The need to modify Ks is explained below.

The overpower AT trip setpoint when operating at or below t he nominal T,y is determined by the E constant of the overpower AT trip t set point equatlon. The inct en se in the inst rument ation uncer t aint les associated with temoval of the RTD Bypass System results in an incresce in the safety analysis limit value for K t. This f ric r e a s e is reflected by the increase in the Technical Specif ication TA value for overpowet AT (the saf ety analysis limit value for K,cortesponds to the nominal K value plus the f ractional f ull power AT equiva. lent of the Technical Speciffration Th va1ue). Accommodation of the increased instrumentation uncertainty by increasing the safety analysis limit value f or K, allows the Technical Specification value for the nominal K 4 netpoint to t emnin unaf f ected by the removal of the RTD Bypane tystem.

The increase in tha saf ety analysis limit for K wa s accommodat ed in 5 the analysis by reducing margin available in the fit of the over power AT t r ip setpoint equation t o the 1181 powet loop LT data at average temperatures less than or equal to the nominal T,y. The increase in the saf ety analysis limit for K4 however necessit ated an increase in the Ko penalty term in order to maintain the t rip set point at or below 1182 for a range of average temperatures greater than the nominal T,y. The propobed increase in the 1erhnical Specification value for K6 ensures that the 1182 power limit will be protected at all average tempera ures.

Since the overpower AT trip with the modified setpoints will continue to ensure that the lle: overpower limit is protected for all ranges of operation, there in no decrease in the margin of safety.

2. 3/4.2.5. "D!lB PARAMETERS

• Page 3/4 2 10 The cur rent Technical Specificatien Surveillance Requit ement 4.2.5.3 specifies that the precision heat balance must be pettotmed prior tr " :tation above 75% of rated thermal power after each !uel Ic . Vestinghouse has recommended that the precision heat balm. e be performed tbove 901 of rated thermal power to minimize measurement uncertainties that are exacerbated at lower power level s .

11ew Hampshire Yankee has theref ore proposed a change to Surveillance Requirement 4.2.5.3 to require that the precision heat balance for determination of RCS flow rate be performed prior to exceeJing 952 cf rated thermal power.

New Hampshire Yankee has also proposed to increase tP' Reactot Coolant System flow rate requirement of Technical Specification Limiting Condition tor Operation 3.2.Sc from the current value of 3

391,000 gpm to a new value of 392,000 gpm to reflect the increase in flow measurement uncertainty as documented in VCAP-13181. The proposed 2.41 flow measurement uncertainty value includas an additional penalty of- 0.11 flow to account f or undetected f eedwates' venturi fouling as stated in the Bases for Technical Specification 3/4.2.5.

3. Table 4.3 1 ' REACTOR TRIP SYSTEM INSTRUMENTATION SURVEILLANCE REQUIREMENTS,* Pages 3/4 3-9 and 13 Note 12, relating to verification of RTD bypass loop flow rate. has been deleted since the RTD Bypass System is being eliminated.

4 BASES 3/4.2.5, 'DNB PARAMETERS," Page B.3/4 2-4 As discussed above. NHY has proposed to increase the DNB parameter -

limit on RCS flow rate from the current value of 391.000 gpm which includes 2.12 measurement uncertainty to 392.000 gpm which includes 2.42 measurement uncertainty. The revised value for RCS flow measurement uncertainty has been reflected in the BASED f or Technical Specification 3/4.2.5.

New Hampshire . Yankee notes that the deletion of the Technical Specification f or the Low RCS Tavg coincide t with teactor trip f eedwater isolation Functional Unit (Table 3.3-4.- Functional init 6.b) that was - recome.cnded in WCAP-13181 will be addressed in a future license amendment request.

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