ML19224C174
| ML19224C174 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 08/13/1975 |
| From: | Suhrke K BABCOCK & WILCOX CO. |
| To: | Schwencer A Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML111230347 | List: |
| References | |
| NUDOCS 7906290273 | |
| Download: ML19224C174 (4) | |
Text
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38bCOCh&Wi!COX Power Generetion Group P.O. Don 1260, t yntnuurc. va. 2C5 l
Telephone: (E04) 3M.5111
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August 13, 1975
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}ir. A. Schuoncer
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Ciicf. LWR Dra:sch 2-3 Division of Reactor Licencing Of fice of Nuc] ear Reacter 1:egulatica U.S. Nuc1ca' Regulcrory Com:irsion j'
-Vashi n gt on, D.
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20555 Daar Mr. Scheencer:
This letter is in retponce to ite'a si: in your April /., 19 75 reques t for additional inic a.at ion on several generic topicc.
Item six is:
"There is not sufficient inf er.nien in S ARs to deterrine that r o t.
design, uti] icing the high and la; prcrsuriner le'>el sirnal, in lieu of the hi gh containment. pressure signa), will provice an cquivalent. derrca of assur mr.e that the a caci or vi:1 trip priar to or coinc ;. 1r with F.CCf ettuatdon.
'1 h e < t : f f concluden L: m if the analysis for the eff( - t i ven e t., of t h..
ECCS riorranc; takes credtt fc: a rea r t.o r t rip, ce require that } d diverse sipals ar r.unti ne. the ':CCS be used to trip.he rextor, therefore, cither (.. }
ad. f: youc de ;i tn to ine]us a high b u i ] uin:, pr. nure trip,to trip the r e a r-t or ; or (b ) tec.onst r t'
hat hi;-h cuc i c..
precsurize le..I ri;;nal rill perf orm et.icfactoril-
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acci dc at con c it i e.3, and.71: trip th-reaci_or prior to or coi n c i G :-a t rit h LCCS act un L ;or, th e reby.:Lr.u. in;; e f f ee t n emergent; core cooling.
include in your rc.y nce chat assurance is provided that this leve] rcasurcrent vill r.aintnia itc accurccy during 1;2 cxdoun."
EbW deec not, see a problen eith ECCS actuation prior to reccror trip, ner is D6W auare t.at it is a technical requirecent that the reactor trip prior to or coinci den t '-ith ECCS actua tion.
As seen f rom the at cached figuro, which is typical for a 205-fuel asser. Sly :S S,
f or all LOC.',' c gr ea te r th an 0. 5 f t2, peac, tor trip uill occur in about 5.C seccads, and ccre flood actuation would occur in about 9.0 secondr.
At least a 25.0 reconds tina delay is applied to the UPI Sycter cetuation and in most analys-s, a 35.0 seconds delay is used for connervatinn This dolcy is due,to sequential loariing of the diesels and ESTAS buses.
For brcrhc down to 0.2 ft cit actu.. tion is later than 100 seconds and reactor trip occurs nrior to 15 secondc.
hence, vith the 25 sc.conds delay on liPI actuation, reactor trip will occur prior to ECCS.
The trip design of the RPS-Il and ESFAS c cets all the requirements c.t,ted in IEEE Std. 27f-1971, the NRL Cencral Design Criteria, and the r.tnadards referenced in Section '/.3 of the safety enalysis reports.
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?abcoch 0.Wilcox
?!r. A.
Schwence r.ugust 13, 1975 Tne RPS-II uscs tuo trips for LOCA protec tion; lou RC pressure and lou nressu-ri er le2nL Lcw RC pressure is the prima rv trip fo M lete spectrum of
' n CA's.
'I'ne use of thic trip is described in Chcpters 6 and 15 and it should be noted that for sor'c breaks no reactor trip is necessary or ascumd.
Tne.nrr;ssurizer icvel--t r.i p.i._s p r.ovi.d e d-s o l.e. l..v~an a bac.kup. trip and is not used in the LO'a ancIvsis.
It is p-evided as a trip because it was RIt that the consc-
'c;dencW 5f a LOCA wcrrant the inclusion of trip hated on a vc :ac]e diverse from hC pressure.
Decreasi:m pret ' uricer Icvel is indicative of cli LCCA's and therefore is an acceptc'r]c bachap to Ic.: I'C press ure.
2nere 1s no need for an RPE backup trip for 3 nrge breaks ( g r.;a t e: then 0.5 ft-).
At this ti:N none o f 'C J' s LT' ar.a2' res take c re d i *. fer reretcr ;nutdeun,,
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na ch ni n - othcr thi.n ecic for _ tion.
.% re" iniect2on G "?) plus rocs are u m to prevent a return to criticalit; during re flaocin g.
For thin action boron injection alonc vould be auf.fi ci ent.
Fo r b re u: s n 2:.
c=> as 0.2 ft',
ths prc: curize' 2.-
1 tr p "i]2 he tantet th.n uil] n e vs. r b e the trac t or 1,ui ldi a c, nressure trip.
Tor terrain s :.a l l c : ecc.s tw a reacto- 'uilcin;,piersore trip Tor the Srs11est bro :n the p e s ori:e r u' il naintain r.w ter ceol:nt syrae-nressure md inventoi-intil it es out auc,
ess?ntin3ly ne cdis'TCc cn d i. i rm "; are Cicatec 45thjn she p ri t ci S Y ". t : ' a al3DI LD tne levci t:,- :a r t r e :>
le :he pri m tv ic;p n
trip ni; -:
In this case toe pressuri:.c r node.
Tor b rea':s b e tue en 0. 5 re d 0. 3 f. 2 the t:1p c;-
- r. l s f rors catainrent orco<ure or prcncuricer It-el are to close in t i t.c that the dif' rence ir : ar i.:ni f i ce.n - in view of overc1] accidtat tiri g.
An c:-:arple of := advan ts:+ of usir e a prennuri?.er leve c: ; j aver a renc:.or adirhat ic c>:pucica analy sin of '
b uil d i n t, prcssure trip can be obtained b:. d ain t, an m ulc an:t:
the prcr surizer into thc coa t a.n: ent.
ror a certain r.ize the n.,....
b reah, c round 0. 2 f t.', the pr csuricer dicchart es at t:a. s ar - rat e as the bicah Tnis is because the s ur r,e line flew aren is Inrypr inan the brerd: and becau::e of the licitation to critical ficu at the break.
Tne nass of fluid in t 'ic reactor buildine at the tir2 of pren.n::ur dry-on-is therefore eque.1 to the initial presnuri.:cr flui6 inventor 3 Calculations sbcu that reactor buildi.:; pressureF are ne nore than 3 psig fer this sice breah If am ec.na j n:ren t heat sink action is 'rutIdcred, this pressure is greatly reduced.
Tnus, et least for certain si ::e s of rupt ocen, the pressuriner levc] trip is cicarly superior to the 4 pcig RB preenure trip.
Tne ES FAS ut-il j re Icw RC pressure cnd hi gh RB pressure for LOCA detectors.
11ere apain L::e l et-RC pressure si gnal is the prinary tt:p and is th~e only one tchen credit for in the accident analysin.
Ta e RS prensure t rip.in an acceptabic backup since increasin:, P3 prenr.ere in indicative of LOCA and steca line breah inside the c on t a i n ru n t.
The 1:SI'AS cnd the PJ'S do no t sh a rc p r e.n s u r e s e:'s o r c.
The W'S sensorn a re nr rcnge (1500-2500 psi)
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- abcoc!: MYilcox s
Mr. A.
Sch muite r Aucunt 13, 1975 It is t.be intention of B6U to modify the pressurizer level sencor piping so that the problen of effervescence in the r? ference Ic;; during a LOCA vill be resolved to ensure accuracy during blowdown.
This will be performed using a bel]cws scaling device that will prevent flaching or gas coming ou: of solution in the reference 1c3 D6U bcs concluded the Jow prernarizer level trip is a satis f actor; backup ::ip.
If you have any questions c i the above, plence call re.
Vet / truly ycurs, EA1;COCh 6 U]LCOE CC:'" A';'l
!!uc le n t lv er Centration
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