ML19344B413

Responds to NRC 800821 Request for Addl Info Re Util 800321 Request for Amend to Tech Specs.Discusses Degraded Grid Voltage Proposed Time Delay Relays

ML19344B413
Person / Time
Site:	Peach Bottom
Issue date:	10/14/1980
From:	Daltroff S PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Reid R Office of Nuclear Reactor Regulation
References
NUDOCS 8010200584
Download: ML19344B413 (4)

Text

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Re: Dock'et Nos. ~50-277' 6~

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Mr.~ Robert W.tReid,' Chief

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Nuclear 1 Regulatory:Consission

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d Reference?l --

Letter,fPhiladelphia. Electric Company.

d J(Bradley)~to NRCJ(H.-R..Denton), dated March l

' g.:m 121,;1980

-Refesence{2::

Letter, NRC (G., Lear) to Philadelphia Electric Company'(E.'C.'Bauer, Jr.) b. dated ~ June 2,.1 9 7 7--

o LReference 3:

Le.tter, Philadelphia. Electric. Companyc(S. L.

Daltroff) to NRC (T. A.;Ippolito), dated

December 31',01979.

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Dear'Mr.cReid:

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a if nf ornation{oni ourJMarch J21', L19_80f,Jrequestff of an amend'iiiehiTo *

- # s; Yourfletter d'ated. August-21,.1980, requested 4edditi'onal

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L ehe'cPeac.h.Bo t_ tom Unit %2+ and T3? Technical"S ecifications.

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!.1^.-<)Referenceiliindicates'a[+5% tolerance in-th'e' degraded grid-M

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! voltage: relay 5setipoint ic.90% of.4160 v'(37.44~ volts)',:

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~Tallo. wing;the'setipointLeohvaryLbetween 3952; volts and 3536

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@i T.* h s.flowest-acceptsble7 voltages (3740 volts).1respe.ctively,i3,lTableiliminimum steadUs c

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for.'a 36ssibl'e spurious 1 trip ian'd/or damaging Classi1Ej equipc:ent.

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TwobdifferentDtypes?ofirelays,Can'NGV fn'd ajCV-6,;will(be

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.1 providedsongeachioffthebfour energency?buseslper unitfto monitor.

g theiof f si,te' voltage.7 The ;NCV! relayfis ianL ins tantaneousf 4,

.g i(undervoltage" relay whlcharov. ides sharpicutof f characteri's' ties i s px

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that42will< tripfthef s.ource liiFeTidiha390%ivoltagegeveli._

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Tovprov.ideiadditionalfassurance.that.the setpoint of.thelrelays;

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iwillEnotJdrift:below theh90%11evel,.we'will1calibratenthem'every,

,5 refueling 1 outage? as' per jthe NRC - S taf f: requirement'. 1Atithis'.

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{"g increased). calibrationif requ'ency ' we t will,be able(to.identif y Tany!

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-variationcin7the'. voltage'setpoints.

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Inithefunlikely' event:chatiche setpoint for-both relays oCthe i

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-sameibus. drift to the 85%.leve.1 and: the'offsiteLvoltage does g'oD

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(be1owi903 kthe(contro1Troom.operatorewill be made aware ofstne

gt idegraded voltage,because he will receive an alarm upon7ecansfer f~? '

iofJehe.other.three buses and~can manually transfer the~ remaining-(busitorthe otherl source.

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.'Infaddition, the(minimum _s teady st ate' voltage._(3 770 : volt s);f rom" H

~our.12/31/79; submittal.only"results'from an extremelyHabnornal

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offsite source 5(there=islanradditional.5% boost' capability in the 1

other offsit'e so'urce)', rand'the' remaining'offaite source operating t

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• iTe~erconnectionslimit of-95% (sizable amounts-of M'

s system l..er,soad.wouldthaverbeeni she'dl prior,to this. time). 'Even under s

MNY ~ L he'seiconditi'ons, the voltage"at E he emergency _ buses is_.not less t

t than the190%'setpoint,of the relays.'

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_Jand?th'ercontro13rooacoperatorsiare'aade aware:of their

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1. r W W l(c)}These'aergency-b'uses are never(.exp'osed jto. aivoltage n of 11ess.

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(than#90% andnonlyca.tvery:lowjprobability-series offevents can "f"

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any oneTof these5threefrelays.will' initiate thertransferLto.

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'the alternate. source.-.." Reference 2, Enclosure 1, page.2,

' i states 1that "Thekvoltage protection:shall include coincidence logic..."= Explain lhowfPeach Bott.on Unitse2 and 3 meet this j

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1 anyjoingleicomponent?f ailur. :jThe f ailure :of.- any :one.of the 5

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ithreeLrelays-referenced'above;to. operate correctly =will"not[cause Jthe{ loss:oflanlemergencysbustualess<there is.'a second' coincident-Mi

" failure.N Even'lin,theicasaloflaJsecondffailure'which causes the j

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.flos's~offa.busf, therecare threatemergency buse's remaining-which is f

theCnumberlassumedioperable for response toJa Design' Basis-c 2 Accidents (DBA).-- LossRofdan;eaergencyDbus has,been analyzed for-m

~ a11Taccidentleventsfaince4th.is;hasialways be;en considered a d

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Toysummarisetthe7coincidenceLlog'ic.of the voltage protection for am -

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- 1Referene,ef1,fyroposedfT.$ Upage,qpage 81, Estates'that1 4:

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Eca11brationLwill'be.~once/5l years..JExplain~how Peach-Bottos-

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