ML19224C172

Discusses Item 3 in NRC Re Main Steam Line Break Inside Containment & Engineered Safety Features Actuation Sys

ML19224C172
Person / Time
Site:	Crane
Issue date:	07/29/1975
From:	Suhrke K BABCOCK & WILCOX CO.
To:	Schencer A Office of Nuclear Reactor Regulation
Shared Package
ML111230347	List: ML111230346 ML19224C151 ML19224C162 ML19224C164 ML19224C169 ML19224C172 ML19224C174 ML19224C180 ML19224C184 ML19224C187
References
NUDOCS 7906290259
Download: ML19224C172 (2)

Text

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t Power Generation Group abCOC!(&iedilCOX

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.,s July 29,19 75 N'

'O br. A. Schuencer

..s i-4' Chief, LUR 3 ranch 2-3 Division of Re ctor Licencing.

Office of I:ucicar Reactor T,crulation U.S. Nuclear Regulatory Cor.=ission Ucchingtcn, D.

C.

20555 Dear "r.

Schwencer:

This letter is in response to iten 3 in your April 4, 1975 recuest for.

addition'l in f ort ation on several geric tcpics.

Itc= 3 is:

"For the cine cf a sten:a line hrc.,h accident inside cent.ain-2nt it is arsurad that the r.ain s t en-- J i ne isola t ion valves and the feed-cater iseletion valves to the affected steam r,enerrter c3cse.

Demonst rr t r-that in the event of a stecir line breen j n; ice contalar ant concu'crent with loss of offsite poucr, ne sin g e fai]ure in the n.tir stecu and feed:ater ico3ation - : ces vi ^ defect t h:- s e c.co prc:cct;"c

acticas, ld.ntify v21 irstru ~n,nrien, controls sac electrical e q u..w

ren t that are not c o s ' r.<- d to Class IC' rec;ui rcn:nts fc: unich cae?.i n si:e t ch is taken 5n ;his anc)y.is.

Supp3 t rent your aiscussicr '.;th shc.cin;; t he f eedustcrf :,te- - sys tc r cad iden 2fv c]l ecrpener.t: ta;t need to be actuated in tal case; of a feed-nter/rterr linu break ir ide and outsi de cont.r ' n-ra t.

Shrit -he results of a fai]ure.ade and effect ana]ysis, that c.r. castrates that the receiretantt for feed./ater/

steam line isolation ace

...et uhi]e cllowing cr.rg6ncy core cooling."

As noted in rv "2y 23,19 73 letter, edch of the 'equipr ant involved is beycad the L2.U scope of supply.

Tnis letter provices further informaticm en requi red t o ensure main s cau and rain the BEU equipm2nt.

Tne valves that are feed, cater line isolation uith an assumeu sinr.le active failure and loss co' off-site pour are iiscussed belce nc uc31 as m._ actuatice sir.nals f ron the Engineered Scfety Features actuation Syster (ESJAS), c Clacs lE Protecticr. Systcn.

Tne main stcon iso]ation velves (one rain stcca isol., tion valve per ma2 steam line for c:a.h of the tuo nain nte..- lines p.-r stccr generator) are sciruic cate,.ory 1.

Each of the isolatica valves receives tuo red e.n:.>n t r.sras actn tien si :nals (cne f rem CSFAS Dir.i tc] Subsysten A cad one f ror ESP /.C Di gital St.'syr ter l

B) cor tandin g valvc. c]osure.

"herefore, a sing}e fnilure in the ESFAS uill not prevent r.rii n ct ca line isolation follcr. w u steam line ' creak.

u Tne main feeduater isolation vclves (one nain fc.:ed. cater inolation valve per are n.

mit nain ferduater line and one r:2in feed.: : t a r li n e p e r F. t e r.c p.cr.c cu or )

f ee dua te r c.'

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cater.ory 1.

Tnere is also one nnin fe:-6.zater nnd one startu;:

valve per nain feeducter lir.c uhich are not seisc.ically qualified.

Th e <: t a r

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m 7906 2 90W1 257 037

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abc0CI' L VlilCCX Mr. A. Schvecc:r July 29,19 75 and contru v ' es in each path receive actuation signals from one ESFAS Di g i t.1 S u'-

_.:ce.shile de rain feedwater isolation valve in each path

% elves an actuation sign.:1 from the redunde.nt CSFAS Digital Subsysten.

Since the isolation vnIve is in serics with the parallel startup and control valves, cach of the two =ain feedrmer injection paths (one to SG A and one to SC B) receives reduncant ESTAS actuation.1gnals for the purpose of isolation; therefore, a singic failure in the ESFAS will not prevent r.ain feedeater isolation folle ing a seca: line break.

A1.1 isolation valves dencribed ill closc even assuning a loss of all offsite pcuet.

The effects of single f

'l-"es of the isolation valves to c1cse are ccasidered belou:

1.

Failure of rair stean ' solation valva on affected stear. gen 2rator:

No signifier.nt effect.

2.

Fai)nre of : ain stean isolation va2 *.e on una f f ected s team gene ra t or -

Isoluticn vc]ven on the aficeted ste n generctor prevent double stcar genera tor bic.. dcun t h rou;;b b revi:.

3.

Failure of either rain feeduater inolation

lve:

ain feed. ater fic..' will be terrinnted by clonere of rne rin icedwater cod startup fcecrater centrol calves in serirc eith the f:iled inclutic:-

/a2.-.

/lG At this t i:r, it is anticipat ed that the ESTAS r.ing]c fc lure m !vsii j

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' : 7., 23, 19 72 1c t te r,

.511 oc sub.r.itted to the I:ugu]c t ory

!.j referred to in -">

Staff in a tcpical report in early 2977.__

If

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- - -. s The cbove infornction la generally apnlicable t o E!.'..' plants currently in the constructic, perrit review s: age.

If you have any questions on the above i n f o rn.a t i on, please cc 2 c.c.

Ve ry t ruly yours,

BABCOCl: <. WILCOX CO"P/C.'.

Nuclear Poaer Gencratica lf.

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.<.N O f

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1:enneth E.

Suhrhc Manager, Licensing KES/db 257 038 e

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