ML18041A274

Evaluation of Topical Rept NEDO-24934, Emergency Procedure Guidelines,Rev 2,BWR 1-6. Guidelines Acceptable W/Listed Exceptions

ML18041A274
Person / Time
Site:	Nine Mile Point
Issue date:	05/05/1993
From:	NRC
To:
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ML17056C371	List: ML17056C377 ML17058B421 ML17058B422 ML17058B423 ML17058B483 ML17058B486 ML17058B491 ML17058B504 ML17058B509 ML17058B511 ML17058B512 ML17058B515 ML17058B516 ML17058B518 ML17058B521 ML17058B522 ML17058B527 ML17058B531 ML17058B534 ML17058B535 ML17058B539 ML17058B542 ML17058B546 ML17058B549 ML17058B554 ML17058B564 ML17058B576 ML17058B581 ML17058B585 ML17058B589 ML17058B590 ML17058B592 ML17058B594 ML17058B598 ML17058B600 ML17058B602 ML17058B604 ML17058B606 ML17058B609 ML17058B611 ML17058B619 ML17058B622 ML17058B625 ML17058B627 ML17058B631 ML17058B632 ML17058B633 ML17058B634 ML17058B635 ML17058B637 ... further results
References
CON-IIT07-495-91, CON-IIT7-495-91 NUREG-1455, NUDOCS 9305050166
Download: ML18041A274 (80)

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~ 1 EVALUATIOi! CiF EHERG-llCY PROCED JRE GUIDELIllES REVISIOl) 2 Pil!R 1

THROUGH 6

('i>~l1'lli'.).i Th Bi!R 0( n l s'roup,

'L.ii.h the assistance of Gene"-1 Flectric, has devel ol.ed.generic syl"ptol:6 ic el"ergeflcy procedul 6 cui del ines (EPGS).

The EPGs are generic to GE-Bl!R 1 through 6 designs in that th63i address call Najol systel.is

'L'ihich riay be used to respond to.!ie ei-,ergency.

Tile guidelines are l'ritten for plants as they are currently conificured; no I

attel"..pt has beel remade to propose systell I",:odificatioris.

8ecause ro specific plant includes all of the systerls in these guidelines, the EPGs are applied to individual plants by deleting staterents i'hich are not applicable or by substituting equivalent S3istens fail.ere appropr".'ate.

For 6"avple, plants lI-'th no loi. pressure inJection s3st n;lill delete staterents referring to LPCI, arid plants l,'ith low pressure core flioodinig lii1 1 subst i tu.e LPCF for LPCI.

Although considerable effol't has been expended by the 8!'f'. 0'o'nel s Gl'oup an('- Cc..eral Electric in t!;e develo",,r. nt of the EPGs and the E."Cs have beeil crl 1 ca 1 ly 6'.al.". tied by severe

. rer..bers of the sta ff, ope rat i lig 6Y.".6 1 ence 'l'i I 1 all"ost cel ta inly reveal si tuat; ons i hi cl: are not covered by the EPGs.

Hoi ever, the procedures iihich iiill be developed fror:; the guideline should be mucli P:ore cor'.prehensive and less volumnous thali the procedures they replace.

Also, because the operator using procedures based on the EFGs nill be responding to synptGGls 'latller than ever s,

an incorrect event diagrcsis i;ill be cf little ccrsequcnce.

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~ J ig The entry conditions for the EPGs are symptomatic of'oth emergencies a."d events

>>hich may. degrad into emergencies.

The guidelines specify ac I i c ns appropri ate for both.

Thieve fore, entry into procedures developed from t hese guidelines is not conclusive that an er'.ercency has occurred.

For example, a less of dvy;:ell cooli operatirig v:ill result in a high d> J~";:ell tempera ng v;h'.le a plart is iure and pressure

<'ith a resultant reactor scram and ECCS actuation but an emergency i'ovid not rece saviily exist.

TI;e EPGs ave ba cd upon maintaining core cooling and primary containment integrity.

Fot the most degraded plant conditions, the in,egrity of tIe primary containment is given priority over coi e cooling.

For example, step SP/L-3.4 of -;.he containment control guidelines s.ates that v(hen the primary containme t 0,'atel level reaches the maximum safe primary containment viatev level at 0 psig or the highest col.ainment vent e'ie~.atiion, the cperator should terminate injection into the RPV.;=> om sources extern'".1 to the primary contairment irrespec.ive of i-hether acequate core cooling is asst.red.

The basis for this step is that flcodinc the pt imary ccrtainment above tl e level at r hich the h,drostal c head equals the Yield stless of 'hQ conta nl".ent at the limiti,",g'location nav result in a b>;eaci of contain",.en:..

I>ecause of extve','.e nla 'vl 6 of this step, it is expected tha 'l s ite uti 1 i i y ma na~erent, ena ineevina st aff and cpevations st aff i'!i11 ra!:e every effort, prior to reaching the tlaxirum Primavy Containment l!ater Level Liimit, to arrest the accumulation of i!a+ev iv, ti e containment without terminating cere cooling.

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The EPGs are functionally ciivided into ti~o guiclelines (PPV control guidelirie ard conta4.ri:ent coni"vol guMel inc) and seven crrtingc.rcies (Level Restoration, Emergency PPV Depvessurization, Steam Cooling, Core Coo'i',ng l:.'ithout Level Restoration, Alternate Shutc'oi,n Cool':ng, PPY Floooincg, Level Pc> er Control,i and are desiignc;d to cover all eri rcency si':options iincluding All ':cipated Transients l ~:bout Scii-m (AThS).

Tl;evefore, sr;.all-bren'.,

LOCA, la.ge-break LOCA,.ransierts i<ith multiple fe,i lures ov ro failures, and inadeouate core cooling ave al 1 addi essed by the EPGs.

The guidelines address 'operator evvors by cl>eeking t",.e ef";ects of directed operator act-oris and provid.r:c-cuidance fov those cases Ilhere previous cpei ator actions i!eve unsuccessful The gu'.del'.ries do r.ot address combustible cas control or seconidary con",aino.ent co'itvol bu. tiiese l'!111 be addi essed in future revis 0n Gi the guidel ines.

In the reantive, there exist ecuipment procedures that could l,e used by operatcl s, hut they a ve not speci fica 1 ly tvea ted in ex ist inq er.ergency procedures.

Tlie guidance provided ov everits <!ith failure to scram is coi-plicated and !iay result in co. e flo!! oscil iations;or ATIL~ even s; hov:ever, core mi lt should be avoided if the AT/iS guidarce in the 'EPGs is i 0 i IGL"ed.

The

!'iTl.'S guidaric>> appears to be the only viable option (fov AT)iS cond itions )

i oi the syster.:s

..hat currently ex ist in ":he pl ar:.s.

TllE EPCs ave organized to provide cuicIance fcr operator respcvse ic ti<<rsients ard acciden.s ov tl>

ent->c, rar,ge of available sys:.cr.s.

Guicarce is provided fov the u e Gf all sy ter>s capabie of pevforr.'.ir.g a

funct:on.

This "defense in cdepth" is discussed in evaluations o

individual guidel nes and cont-:.ncencies.

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iQ The guidelines use a unique method to coordirate ac.ion: of differeht guidelines.

This involves the evaluation of the necessity for an actior in one gu',deline or ccntingency->!ith the instructions for ".he action cortained nithin another g'ideline cr contingercy.

Pn example of this is emercency depl essut izatiori.

I"s need may result from cortairrcnt, contt nl difficul ties but iits steps are in the Emergercy RPV Depressurization Contingercy 8'2.

This organization is necessary to ensure all the considerations associated t.ith this action are addressed fol ali situations.

This method of coordinating these functions is acceptable; ho)'iever it may bc difi icult to 'mpler!eiit this mechanism in procedures using this organization.

The procedures reviewed in the pilot monitoring program (TtiI Action Plan Item I.C.B) v!ere developed frcm an earlier version

o. the guidelines.

Th refore, the Procedures and Systems,Review Brarich >~H1 scrutinize plan for the implementation c

th guidelines.

5Ut'!","'"Y CiP LEVEL CC'i'iTRGL The purpose of the RPV control guideline is to restore and maintain RPV h'a i er level i'!ithir, a satis factory range, shut do)'!n the roac;Or ard I

control RPY pressur.,

and cool the RPY to cold shutdo<'n condi';ions.

The entry ccnditicns are any o" ';he follow;-rg:

1)

RPY ('ater level helot( low level scram setpoint, 2) drys!eil pressure above the high dryvell pressure scram

setpoint, 3) an isola.ion i".lich requires or initiates reactor scram, or 0) a condit~ion 'l:hich requires reac.Or sclam and reactor pober is above the

&PRIES do<;nsca;o trip or cannot be determined nr

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PP'l pressure above the scram pressure.

Fol events in which cram occurs, either automaii call)

Gl manually, the o",eiator verifies scram and proceeds to control FPV i;ater level and pressure i ith whatever systems

<<re avallat>e.

Tile sy" ems used.to in-.ect watel" a) e listed in an appro>:imate crdev of preference and beth safety and non-safety systems are ircluded.

hheve possible, i>>ater level>

is maivtaired in the n>ovmal con rol range; i.'here this is rot possible level

s either contvolied above

+he top cf the act've fuel or the cpevato attE'i",.pts to vei'ify sufTlciel. injectlGA- (core spl >.y flo'i'! l"ate) to assure adequate core cooling.

Poth.est and analysis have shown that maintai>ring t!ater level above

~he top of the act ive fuel is sufficicrt to assure ac'ccuate core cool ing, provided the reactor is tripped.

The EPGs are designed

.o give

">reference to coverirg

.he core >!ith v!ater to cool it.

Fuvther, test e

a::d analysis have shown

.liat infect cn b'1th one 0

I"Oie core splay J s t ems or flooding tc (/3 core hei ght with 1 oi! pressure systei

.s is aCec> ate to maintain core cooling if the reactor is tripped but the cove cannot be ccmple.ely ccvcred.

The EPCs vecccr.-'ze this mode of cooling as ar. alternate to the p>e errcd r:o.e o= cooling.

If no injection systems are available to ma:.ntain inventory in the reactor vessel, the guidelines prescribe a combiiiation of boiloff and depressurization>

to maintain core cooling while attempts are made to star iroperable systems to vcplenish inventory.

Although this approach

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crly delays the eventual heatup of the fuel, it is the best '.hat can be doA. h'ith AG available ir'ection.

Sl!lilt";.Y Or

!"'Tl S GL'IDAVCE IT scram c'Ges not occur <<'hen requ-') ed, t EPGs cal 1 for several ac iors to be taker. simul taAeol's1 <<.

These include:

1)

Start boion injection i!ith standby iiouid control system (SLCS) or other systems lf SLCS is not operable, arC Hanually insert ccntrol rods, reset

scrars, open b;rat:ers or remove fuses i!hich deenerai..e scram soienoids, close scram air header supply valve ard cpen scram air header i!ent valves, individually oper scram test s>>itches, and 3) ice!cr nater level until:

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po;.er helo<.

I;PRIE doi;nscale trip (31.'s typical), or b ~

conta

!ll"ient heatup terminated, or c.

level reacl es the top of

~! e active fuel in the donnccr.;er.

Al':houch tale Iollering of.he i'!ater level

-'s eTfective in reducing pov'er, result in cove floe; oscil at"aeons.

i'eithol the flot" Gsclllations ncr -'he consequerces o.

.he osciilatiors a.e amenc.ble to analysis.

UEi':ii",!'I'CE Ct'- 1.YT R LE"EL it.'DICATIClP Eecause r.:ary of the actions in the EPGs are I;eyed to reactcr vessel i!ater level, the EPGs contain cautions i:hich alert the operator to conditions which cause the <;a+er'evel inc cations

.o be unreliable.

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Tfiese cautions are rel a.ed to drys:el 1 temperature, inoicated level ard f:.PY pressure.

The limits ir. the cautions are calculated conservatively.

If the vessel h'a ei level cannot be dote mir cd, tfie EPGs ir.s.ruct the operator to depl essur ife the vesse

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c.nd flood the

~essel

<!rti1 v<'ater

,".ours cut of the safety/rel iei valv s.

Ttiis gui2arce assures that the fuel remains covered i,'ith i!ater so that the fu 1 is adecuately cooled.

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OF C('f:TAIHt.iENT COt< TROL Tll coil a '.rment control guideliinc is ccncerned "1 ch pl iimal v containment tempera cure, p'. essure, and >.ater level. it is e"ecuted concurrently v!ith the PP'I control guidel ines.

The entry conditiors are any of the fol lc".!ing:

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suppression pool teMf.'erature above normal operatino 1 imit, 2) dry@el 1-temperature above normal cperatir.g 1 imit, 3) containment temperature above normal operating limit, 4) drys'!el 1 pressure above ECCH initiation pressure, 5) suppression pcol <!ater level above normal operating limit, or 6) suppress ior, pool i!a ter level bel oi; normal opera. irg limit.

The conta inm=nt control guide! ine contains severa'.

1;riit curves such as a suppression poo spl ay 1 lmlt anu a pressui e suppl essicli 1i.ilt.

Beyond these 1 iriits, certain operator actions are recui rcd.

i<1 though the 1 ir.i.s are conservative, they are deri veri ron eng-neering analyses using best-esi:inate r'.odel s.

Consecuently, these 1 ir3its are not as ccnservative as the limits specified in a plant' technical sp cificatiolls ~

This is not to iri.ply tfiat operation beyond the

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I technical specification is recommended in an emergency.

Pother, such Gpe'( atl on sp&cll'led cGAtlnued may be reouired Urdel cei tain degraded conditions.

The liriliis in the guidelines establish

'.Ile boundaries >'ithin I'hich safe operation of the plant can be assured.

Therefore, confcrriance with tlie guidcl Aes UAdev deg.aded cord',ticns do s not ensui"c stl ict coiformance 'I'lith a plant s technical spccif icatiors or other licensing bases.

The licensing specifica

.iors vjill already have been exceeded in order

.o get into such a situation in the first place and the sa,e recovery of the plant becomes the r,:.atter of paramount ll".jortance.

S'llULTPhEOUS ACTIAVS Although the operator could be using several procedures sirlultaneously, the s imulatnr demonstrations of in.erin procedi'I'es for several plants that i ere based on the guidelines have demonstrated that ccntainment parameters zo not change vapidly enough to be beyond the operator's c< pability to respond.

9"!'fllJC !ih!U.'.E OF GUIDEl 't,'ES Pf!6 CF'E!

~TEI!S Because the B!.'R 0:ners'vcup may disbard aftev tliese guidei-;res are 1

cppvc':ed, there ls a riced OI a group consisting of Ol,"2 Gl"Aeis aAd Ceneral E! E'ct r 1 c to co "pl e the deve I op!"',en i: o the gui dei: nes and to Iialnta n tljc guidoi ir'es af'r Geve loprient is cor:piete.

lhe d=velopment cf the guide'lines riay be cons.'dered complete after cor.;bustible gas control and secondary containrent control guidelines are reviewed ard approved.

I'maintenance Mould in'elude incorpovation of operating

experience and new krowledge into the guidelines and modification of the c.uidelines to <<ccouot for new equipment.

In addition, several steps in the guidel'ines require further worl':

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Cr !tel ia for defining con-';ainreni'enting pressure reed to te det rained.

Interim values are given in this evaluation, 2)

Conservatisms in the determination of drywell spray flnwrate need to be reduced, 3)

The RPV flooding contingenc.

needs to..be -revised to rzl'.e the depressu> '"ation step more expl'.c',t.

The actions.pecified in the EPGs are generally corr c. and appropriate

=nd within the operator s capabil-i'y.

The combination of all nrergenc'ctions into two guide'.ines and seven contingencies greatly simplifies the emergency instructions.

In addition, the use of symptcms rathe~

than events as bases for actions eliminates <<rrors resv':ting from incorrect diacrosis of events and addresses multiple failures and'peratcr error A more detailed discussion of individual guidel'i es and co-tingencies follows.

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RPY Control Gui del inc Ti e purpose Gf the venter level within

pressurP, and cool

~PV control gu',del inc is to 1 cstore anc !".alntain RPV a satisfactory. range, shut doe.n the reactcr, control the PPV to co r d shutdo;;n conditions.

Tl e entry cond ition are any of the follos!ing:

1)

Peactor p-cssvre vessel (RPV) i';ater level bel os: low level scram setpoint, 2)

Dry;;el 1 pressure above the higl. drys'ol 1 prcssure

scraa, setpoint, 3)

An isolation v,'hich requires or iiritiates-reactor scrali, 4 )

A condition v;hich requires reactor scram and reactor po<;er is r

abcve the APRli doi":r;scale trip or cannot be determined, Gr 5)

RPY pressure above

.he scram pressure.

The first step in this guideline is to ir.itiate reactor scrari if it has noi bear; ir itiated.

The RPV control guidel ine then branches into three segrents

( level control, pressure

control, and po>;'er controli )>>hi ch are executed concurrently.

0 LPve1 coll cl Gl Level cor:.101 atter'lpzs to ccntro

~ reaccor>>a

'.Er level boti"een the 1Gv!

>evel srrari sei.poiint ano the high level trip setpoint.

If 'L".atol level canniot Le r:",a ir ta incd above the 1 oi'r 1 evel scram setpoint, tlien level control a'empts to mair tain tl;e i ater 1 eve',

above the top Ol the act ve fuel. If level can be rcaintained above the tcP of the activP. Tuel ard the ADS tirrer l.as initiated, then tl.e operator is instructed to reset.

tl;e ADS tir,er; this may require

'frecjuent resett

.ng of the Automatic Depressur i=ation.System (KS) tir er, Foul Gf the seven contingercies

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are called fron leve', control.

The conditions under v:hich these are ca'.led are as folio~;s:

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Eoron injection required, enter level/poser control contingency 2)

Peactor pressure vessel (f'.PY) v.ater level canno" be determined, entel RPL floooing contingency

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RPV loodirg required fe.g., drys:ell or containment temperature near cold reference leg instrument vertical run reaches the PPV saturation temperature; suppres ion chamber pressure cannot be maintained Leloiv tl>e primary containment design pressure),

erter RPV flooding cont',roency 4)

If RPV i:ater le 'el cannot be maintained above the top of the active fuel, erter the level restoration conting rcy '

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If al i errate shutde;n cool i ng i s required, enter the al ternate shutdo'l'(n cool ing contingency.

" Each nf the contingencies will be discussed separately.

For a typical recovery from.plant tt ansicnts there v(ill be no need to call upon ary of thc contingencies; the steps in the level control portion of the RPV control guidelines are simple and they are adequate to assure that the core is covered >.'ith <.ater.

o Pressure Control Tl e PPV pressure control section cf 'e RPV control guideline contro as pressure such that safety relief valve (SRV) cycling is minimized anc<

suppression pool heat capacity and load limits are not exceeded.

The steps of the PPY pressure control section are adequate for normal recovery from plant transients an( cooldo<in to shutdo;;n cooling.

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"12" emergency depvessuvizaticn is anticipated (not yet required), the-operatol

',s instructed to rapidly Ciepressuiize itle PP/ )'".th the

))B n

turbine bypass

valves, th'.s reC),:ces ihe heat load on the suppression pool.

The t)eat capacity te)iipe) atuve lirit is established such

.hat, siavting from any p) essure, the suppression pool Mill I

<<c o)<mode"te rapid depvessurizatinn without exceeding the naximur) allo>,able suppress',on pool tempevatuve.

The suppression pool load iinit is established by B curve that ce 'ines )'/hero stvess in 'chc limiting.Submerged s;)uctuval co)")-onent equals yield stress for dynamic loads resu'ting from 'R'/

d sc lal ge.

A 10~< load increase for each two foot water level increase was used to define the curve.

If emergency d!p)essuvization, RPI/

'oc'ding, Bltel"nate shutCG)",n cooling ol'team cocl lng is

) eouil ed, cilin pie sure control switches to the corresponding contingency.

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Cont) 01 The reactor power control section of tl)e RP" guideline verifies that rods are insovt&d and the leBctor is shutdo;:v.

The operatol is tl)en divcc'ed to the scram procedure.

The 1 e)-..Bin<<'e)" of the pnve) conitrol section ceais with these steps (oti)I~V than v:Bte). level ccr trol) to b;-'.<g

he reactor

.0 B shutdown co)dition ir the rods diid r<.t fully irsevt or

'I; tie reactcl powel i

above the APPI i

( ""nscal e

')'0 p 0'v canno c be C Ctel mined.

The VeaCl Ol PGWPV COn' 01 SeC i On) 1 nCl udeS Such S cePS BS place the reactor rode s'(itch in shutdown (provides another sera-.)

signal), trip the recirculation

pumps, in'.ect boron before ihe suppression pool te).pe) atvre reaches the boron injecticr< init'.ation

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te)-;porature (typically 220'F) and insert control rods by various means.

If t()ese steps do not >:orI:, tIen continge >cy:'I level/po)"er control, is used to control po<!e). by other means.

One s;ep in the reactor po)'er control section is ir)practical fo) failu) es to scrar>>.hich result in vessel isolation ard ray not be p) ac ical fo) other fallu) es to sc) afl, Step RC/0-4.2 states "If boron cannot be injected )vith SLC, inject boron into the RP)I by one o) more of tn fc:":.ing alternate methods:

o CRD o

))PCS o

Rt CU o

Feed); a ter o

HPCI G

PCJC o

Hydro pump.

oecause the ti)::e required to add boron to ;he );ater source fo)

.hese systems is large and because sufficient boror, r,,ay.not be avai)able on si e, the efficacy of'his step is questionable.

Ho);ever, the

.'i cbab i 1 1 t<<o, reedir q s.ep BC/(<-4."

.is c,ui+e 1 o<'.

di tel) eTTQ)'t t'lltI) a IG'." p) obability of success.

)h)s step is a "last Qu)

) ev

~ 0'L'I l)as conclu "ed that at least is rot c'et) irental to s2)=ety to t)y this apprcacm) despite the lo<! probability cf success.

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Ccntainment Con.rol Guideline The conta':nment control guideline is executed concurrently v!ith the FF'/

control guideline.

Its purpose, is to control primary containment icEipelature, pressure anc level.

Entrv conditions are. any of the folio;!ino:

1)

Suppression pool tempera ure above the r.'.ost limitirc suppression pool tcrperature limitino condition ior cperation (LCO),

2)

Dry;;ell temperature above d> y>;'ell temperature LCO nr maximum normal operating temperature, v:hie( eve>

is hioher, 3)

Ccntv i I:m nt ier.opera ture abo, e its

LCO, 4)

Drys!ell pressure above hioh pressure scram setpoint, 5)

Suppression

(:col v!ater level above its maximum LCO, or 6)

Suppression pool v,ater level below'; its minimum LCO.

The cortairm nt control ouideline has five sections i!hich ale executed concurrently; thes.

are:

SP/T-D('I/T-C!'!/T-PC/P-SP/L-suppression pcol temperature, dry<;ell temperature, containm nt temperature, primary containment p', essure, ar:d suppression pcnl level.

o SP/7 The SP/T

. ect'fcn Gf the coniainnent control c'uideline is euite simple.

TI:e operator is instructed to close all stuck open relief valves or scram the reactor if the valves'canrct be closed.

The opera or is irst:.'ucted tG operate pool cooling w(;en ';(:e pool ter;perature equals or

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-1 5-e"cceds its LCO and to scram the reactor be ore the pool t"mpera+ure reaches the boron injection ter perature (ter!peratuve <<t v hich opevatot is instructed to inject boron).

Also, the operator is instructed to control RPV pressure to r:aintain the pool temperature below the heat capacity ter.;perature limit (locus at points fcv v.'hich stab'e condensat-':on of discI.arge from SPVs is assured).

If suppression pool ter'-.pera ure and RPV pressure cannot be restored and maintained below the heat capacity temperature limit, then emergency I'.PV depvessurization is re.'

d.

This latter step would perm-.+

.he heat capacity temperature

,'.t 'o be exceeded briefly >>.ithout emergency

-depressuvization provided a h-at sink other than the suppvession pcol (e.g.,

main cond nser Gr "isolation condense

) is available.

o Dll/T TI:e 0';:/T sectio~ of the containment control guideline is al so simple.

ts purpose is to monito - and control drywel 1 tern 'erature.

The operator

',s ins;vucted to operate avail ab'le Crywel 1 cooling when drywel 1 t -:.perature exceeds the Cry>;el 1 temperature LCO ov maximum normal operating temperature, whichever is higher. If drywel I te,"'peratuve near the cold rc evence leg instrument vertical rurs reaches ihe I',P" satu ation teEiperatui e (a cuvv>> of satu1 ation

'ei"pel a,ut e vol sus pvessur e is provided)

PPY flooding is rec'uir ed; this step is needed to assure tI)at water level can be determineo following flasl)'i g in the

'.ns rument lines.

Step DI!/7-3 states "Before drywel 1 temperature reaches maximum ADS

(,'ual ifica+ion temperature or drywel 1 design tet",perature, i:I>ichever is

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~ lo!ier, but cnly i= suppression chamber temperature arid drywell pressure a! e belo;; the drywell spi ay initiation pi"cs".ui e limiit shutCO"'n recirculiition pumps and dry<<ell.,cooling fal!s al'd inlt'ate dry",!ell.sprays restricting flail!

1 atE'o liess than max rum dry!;'el i spray flow iate

".-:r:ii:" (720 gpr", typical).

The Cry;ell s.vay initiat-;or: pressure 1 rll is dei'ined to pro 'ect agalnis~

cor!talniient collapse due to negative dii ercntial pressures (ccntainpicnt to reactor bviilding and drv<<ell tc suppression pool

) caused by condensation of stean in the containr>>ent.

Tl;is limit app!ies only te l',ark I ano t'.ark II conteirr;-ents.

The dry<<ell spvai flo<<rate limit ',s very lo<<(approxir:.ately

'!0'. of lew capability) ard is probably verv conservative.

liore!,ork is rceded to obtain a move realistic spray flew limit.

Jf the dry!!eil ter;perature carnot be mair tair.ec bele!~ the ADS c!:.a'.ificaticn temperature ov dry!;el!1 design temperature, tl!en er!ergency depressurizatlon

'!s lpQulled.

Tllis step ls riecessary because the higl.

Cry! ell ter'perature r!ay cause the AOS to becorie inioperable and the ccpabiliity tc rapidly depressuri-;.e, if needed, would be lost.

o CV/T Tl!e Ci /

<<et~on cf the conta;~.cent conti'Gl cuidel re applies to i'ark I'! ccnt~iinr'er.ts and is very sir:ilar to ".he Dl!/T scc';iio;!,or l'<.rk I and tiavk Ii containr!ants.

Tl!e opei.iitor uses avv iable contai!.ment ceo! irg

<<he!! the contairr.;ent terpcvatuve exceeds iits tempe! <..ure L('0.

Cefoi"e containment te!;pe! ature reacl'ies the desicn value, but only if suppression chamber pvessure iis'above the l'ark III centainliienl spray inii;iation pvessure limit, the operator initiates suppressior, l eel

~

~

~

)

P

~

~ sprays.

A single value o

1.7 psig was chcsen to houno plants with ard

>,'ithout vacuun brea!;evs.

if the contai<<rent ter.perature cannot be r,:ainta'ned below the desiqn tenperature, enevoency PP'I depressuviza'.irr is required.

if containrent temperature near thc cold vefevence leg inst. ur'ert vert ical run veaches the PPV saturation ter'pevatuve, f'.FV f1 coding is requ I red.

o PC/P Tiie PC/P section of the conta"',ro,ant contvcl guidelirc ronitovs and controls pi inavy contains"ent pressure.

TI'.e first step should be sufficient for v covevy fvor., most plant transients.

The log'.c or the remaining steps is somewhat comple>;.

in the case of contairment

'enting, there is no well cefined basis for a 1 imit.

After r;.uch d scussion aKonq AE, the owners, and various el er;.ents of the staff, we I cKe settled on, twice the desion pressure of ihe containment as an interim value ov venting provMed containm nt integrity can be Ce4,on stva ted.

The first step of PC/P rerely states:

Operate the folio<;ing systeris as verui ved:

o Coniainrcnt pressure contro'.

sy ter;.s.

o SDGT an 'rys;'el'urge, only when

-;he ter.pere.t.ve in the sp~" ce being evacuated i s below 212'F.

This step sl Guld be sufficient for r:.ost situations.

The rer;;ainirg steps are for progressively degraded si.'uations.

-'ted PC/P-2 states:

Refore suppress i or c!::- r;ber pressure reaches the suppression charhor spray ir itiation pressure

( typ. ca 1 ly 17.4 ps i g fov

e I

I r

1

tiark I) bvt only if suppression chacb r pressure is abo';e ].7 psio (I!ark III spray init~atiog1 pressure 1 iflit) or suppression pool l"ate. level is belG"'iie elevatiun of suppress-:ion pool spray nozzles, '.nitiate suppression pool sprays.

The purpose of tiie f!ark I and II suppression cubi~'l".ev splay ivitiation p-essure 1 im".t is tn veduce pressure before cvJ tell spray is needed (dry<;ell sprays r:.ay r.'-.;r:age electrica, cciuipmevt).

,'he hark III cortaini"er t spray init'.ation prcssure limit has alveady been discussed in the DH/T sectiicn.

The pool 'l'Iatev level lirlitassures that the spvays can condense steam ir. the aivspace; if the rozzles ale su.mevg".d tile spray is nnt effect~ive.-

The re"t step calls for dvi".11 spray, takivg cognizance of suppression ct amber spray initiaticn pvessure and dryl"ell spray initiation prcssure limits discussed previously.

Acain, there is the liiriitcn drys'~el i spray f~oi'( i'ate 0'hich

',s probably too conservative.

If suppvession charber pressure carnot be rif'intained beloi'! the piessure suppvession plessuve curve emel gevicy depve sul'izot10fl 1S iequired.

The pvcssure suppression pressure cur:e serves to 1',riiit pressure to a des'.gn f.vessu!"e.Ci'iol"co."n aiong the heat capacity tel.peiatL'vo i ifiili. and r:.nimizes e:;cessive bypass lieakagc.

If suppression clialii'r pressure carriot be liair;tained belci'i the primary containment cesign

pvessuve, RPY flc'cdiing is vecuired.

Flcodir!g of the RPV should result iii subcooled

'i';ater rather than stean blG'l'ing 1nto the containr,:ent (the ves..el should all-cady be deprcssuvizcd fvom the previous s".,ep).

This sliculd tevilinete "(le conta infi At pvi:ssuvization.

,1 I

4

~

~ step PC/P-6 sta';i.'s that, "I suppression chamber pressure cannot be maintained belch the prir:.-ry containment pressure lirrit, then irrespective of i;hether adecuate core cooling is assure~:

o If suppression pool water level is below'levation of suppression poo',

spvay nozzles, initia".e suppres

'on pool

sprays, G

If suppression charber tempera. ure and drys'el 1 pressul e al e beloi tl e dryMell spray initiation pressuve limit, initiaie drys:oil sprays."

This step elects to preserve ccnta:@rent integrity.over cove cooling.

This is acceptable.

It recognizes the value of preserve;rg the last barrier to velease of radioactivity and it recognizes that if containrent ;ntearity is lost, then core cooling ray ultimately fail fov such overpvessurizat:on events duc to loss of heat s.nk I;ecause of the e: treme nature of this step, it is expected that Gnsite utility ranagcr.ent, engineering staff ard nperat ons staff w!11 make every effor., prior to reaching the Primary CGntainr,:ent Pressure Llfl'ft to veduce the containment pressure or io arrest the pressurization. 'lso, the length of tirade that flow i;ill be c'.iverted fvori core coolirg should L'e short; i.e., if the spray is effective in reducing conia-current

~vessuve, the floi can be iorediately vetu ned tc ccrc cooling and tIe RPV cnnivol g"ide'iire or the

evel resbova ion con.ingency 4ouid instruct t 1e operator to dG so.

Tile r a d'or pvobl em i'(iiI tl is stop is that the Primary Containment Pressuve L:m t is no i~ell defined.

The Primary Containnent Pressure Limit is supposed to be the best est'.r.ate of the pressure at c.'hich the contain;,; nt vup.ures.

Xt is s,ell

<<l I

I o

SP/L Section SF/L of the Ccnta i nme

~ <. Control Gui eel inc mor itors and control s suppression pool water level.

.TI e first step merely vziintains tie. i.ater level bets;een the high level anc lo)( level LCOs; this shcuid bh adequate

<or picst even<",s.

Tl'e seco,.d step gives a heat capacity level limit based on absorbing energy from a RPV bloinio<vn ard states tI at iif suppression pool i<ater level carrot be ma intained above that 1 'nit, emergency PPV d~p< essuriz<-:tion is rccui red.

<'he.hird step of SP/L I as several s!:bsteps ba sed on progress ive i <<.'eases in <;'ater level in the cor <.a invert above the maxim<un<

suppression pool v!ater 1 evel LCO.

TI.us, SP/L. 3. 1 states "If adequa

< e core cooling i s assured, term<i nate inject ion into the PPY from sources external to the primary contair ment." 'f that cannot be accov'plished, SP/I.-3.2 states il;at i= suppression pcol i.'ater level arrl RPY pressure cannot be restored and m<ai n

', red bel ot'! tl:<<suppress'.or poo'I load limit (discussed earl ier), emergency I<,'PV depres ur ization is rccui red.

Step SP/l..-3.3 cells for dry4'e<

1 spray to 1 educe contain:. ent pressure be.ore

';.!<e i at er 1 eve",

reach(:s

+he elevation of the vacuum breal:ersI:above tt:at

'. evei-, the vacuu;".> brea):ers are neffective.

St> p SP/L-3. 4 calls for cont inucc 0)!era tie!

o ')le dry"Ie l I sprays af..er thc vacuur! breakers a! e

<.I:l containment p! essure anc te!!peva ure 3"el <2 c'. I i Gl ed i;o increase after the vacuum bre<"-);er s Ore covered i;ith v;ater, drys.el 1 spray houl d not be reactivated because tI:e caccum breakers

>voui d not be effect ive in 1 imitirg the pressure differer ' al be iP(een the dryvel 1 and suppresi on cl:ar<':er.

Final ly, if the i;-ter level

! caches the fiaxim<um Prir::ary Ccn<tai<.rent I ater Level limit, the operato!

is instructed to te!vii(<<";te in"Ec( ion in

< 0 tile I'P / fr or! sourres ex.c mal i o

0

~

~

I k

the prinary ccntainrient irrespective of nhether adequate core coolinc is assured.

This step iis Lased on preserving containment integrity against failure due to vreight of v'ater in the containment even if it causes

',oss of core cooling and fuel damage.

Thiis is a very drastic step

<!hich

<!ould be required in oniy th= most cegraded ci> c<<."..stai ces.

Oecause of I

th.

e>:t'<'ernie nature of this step, it i s expected that Gns ite uti I "ity managei< ent, engineering s.aff and operations st<o ff i'.il1 make e<.cry effort, prior to reaching the l'iaximvr! Primary Cc n.ainment I'ater Level Linit, to arrest the accumulation of i;ater in the containment without ter<-,:i<:.< tin<g core cooling.

)

~

~

/

V I

Thi s contirgercy i s er tered fror1 the 1 eve 1 control port Ion of the RP" Control Guic!eline vjhen the,operator dcternires that v:ater level canrot Le m=intained above the

+c:p of the active fuel; t:c:ever, the v.ater level may stil; be above tha

.op of active fuel.

Once

> atev level s restored to

<-.Love the top Gf che active fuel, cor trol is re"urned to the PPV Con.rc 1 Guidelire.

If <vhile executinc this contircency horor,. '.njection is required, PPV i!ater level carrot be detevririned, ov RP~/ floodinc. is requ red, contre s('I itches to the appropriate contingency.

The first step in th:s contingercy is to initiate core cooling using the isolation conc!ensev and line up pumps iov lnlecticn from tp'0 or r;;ol e of ihe ECCS

.uv'systems c:r condensate system.

If 1 ess than t> o of ihe rormal ir,'ection subsystems can be lined up,

.he opevato) is instructed to 1 ine up as r'any of the fol lr;~ing al terrate in-:ection subsystems as possible:

0 o

RHP, service v:ater crcss+ie, Five system Intevcornections With other units, ECCS '~ep-ull ~y.*~- s SLC (..est tan!:),

o 'LC (Loron tank).

he cperatov

'.h=n ro. itovs I':PV pressure end >.ater

';evel and cortinues at the step irdicated in the Follow'ng logic tab'.e:

~

~

1

~

~

R?V PR""SSL'c R "G'ZO i 1

[4"5 "sig ]

2 j100 psi-" j" H EGH i.OW

~I.

~

~

I

,sir ~

a 1IG Cl-4 Cl-5 Cl-o

"=CA:-AS:XG Cl-7 Cl"S 1

( -PV 9 assi'.'-:.=Cior ACMIC a t 'vnicn L CS s.aUtoz t hopj is ioccnQQ) h lov p ess' isolation set pci nt, anion v

nipn r)

l I

~

)

h~

I

Cl-3 llO'IITOR PPV I"l'.":ORE !'l0 i!RTER LLYEL.

CG:ITii!O': IH TIIIIIOCL'DIII!Eh1Itl S fl'.l'.IIIDICRI4'D lii TIII-FOLLOiIIijr: T;, LL lltCtl I<fr."> BIG ('))

i"/ I")59lf.

GI('IRLTii

8) IA'[Li till IG ('>>

~ r Qadi BIIHtt~V. K'-Lrr'U) FR~:1 Tt"=-

R'I K~I ClIM.II"II ISIQ'OL).

CL5 IF if%I P.tt) KIC f IDT N!AIU'BEh8 lH Ff~ iS II.JGiSH i, OEMID f<V PJ"iGM<tl-ATI(il IS KEIID. 8""I tf'i'iiKSQL<z. IS KGQS-I!5, HIIBI tt"i~r" K I"%LL'EDFIVIIt'. h Y CCIIIK'.0)IIJ'.ll"-) re tSIEP lK/L).

IF I~it A.J KIC AIR, I.'OT AVAIUSE fi!.')fl'I Pi '%4K IS Nf IIGG51 Kr, BIII:ltIPIKMf.VVBES FIGI Ttr tP/Iffy NILLIIBAT tsfB'flL).

OII."~VIIX,HBI IPI 'BKIEI( LLVd I'D) (+12 Ifl. (K;I LiVJ. SCI(i!I KINllff)),BIIEtt IPIYXHk'i"IMIGRD Fiat TIKle'GtilK Gtttl Llt~~) AT tSIEI'M).

CL7 IF IKI Ct K!C IS tQT Cr"hTtf5. IMAMt.'IIQDilt IS IQT KGNT)t5..

IF t3 C. ) f.'~ IS fT)(LTII5I'ffiT ICi8' lib",QIGIS(Bmft'i PX I.IIS L FCt II'TICII!IIII P K f~;lir~, I."H'.QQ':."'QliSM(17hTIC('I IS fXilttiiD. t.'Ht fP/ I!\\ttl(UVIOL IS ti'.JMI(50 f'4 P ref. P."'5 I"1)'3 Il(Q I >IG (IKI8 KIC L01 PIKKZ IKJiTIQ4 SEfli)tltf, I'IIO'VJl IS Itlex>>, r';iV::,'O iSIfi Ci->>.

IF.n ce r "I ts rr~~utt~ f. ) Ia mrwtLImeF'I ts Lttm tjp rm ttUJTret)IIIIIAT~r 6>> Fi.'P Or.ttt~, STHtf ILiU IllI'UK'ATE ItLF:GIN SSSY"IHH bltQI A~ Lite) lP FN Ii~lQI.

).'Gt R )!IIHtEij. I'~~a 10 (-1Gtl Itl. (TP L. AGILE MU)i O IF ir3 QSlUi, IILF'GIQI Strum

~ IU'I Ct fklEAATLiIitr'GIGI MSYSID) IS LliH) L(

IIITIIATIl'8f0: I'ifP N'-'li5 STEr<I QZLtiKi IS IG~JIN).

I,"Ht Paif 9'SlliL IlU:CIIQ'IMSi~lt'.llL( f'L1U'.".LIE IHXGICI9MSILII IS LltQ) O'IITltAT LUSI KE Lr~ IU"tfl5, f~fll.'rrt TO <SIEP Cl-31.

C ODH'ttK tl3t CID IIVI."'if~(lMIQIIS %COIFED.

IEHI NV B)TB lBG, IS It;uG6lt5 Gt P!V llU8ÃiAS KOI tlM PSIG (IKI Ot Itclc LB MS%1K IK'~1TIGt Z'IIQItq', tr!ICI'YJ( IS IIIQD))r fBKst TO (SILP Cl-3)-

r.u IF IPI Pic%,".."= IS II:JB5liG, BJGID PPI I",Pt'%NI7lTIOI IS tuXUtf8).

I!Bt tfVfit&!f4'SICOOSIIKi, BflN IPii-CB L" I". JQH) I W TI"- PPV MIIIQ.

QIILlIP) AT ISIU'i/L).

(IBi<ISE, HflHt IHKtiUKt&BNS FNI 'fIE tfVCalle PJIIG.IIL) AT ISrZ ltc/L).

~ i CL8 tll'3 I; CS Ctt UCS 9EQSTBl IS CmtATII..) Srsltr IU. S Itt ALID"9'ATE ttt 'CflUIRNsSIBti I,IIQIAK LIKD L" fO:I IIL"GIN.

IF P.'V PfMLK IS Ii~JSisti5, 089uo'V IXFidR~.M7ATIHIIS I~TOtfro),

):Hl R"/ )!LIE LGiLlAPS TO I-lr/I Iiit.

(TGQIKML)) BflBt tPilXHUc.

ILVQl~iiJF~d'. C tfttXBDI"t).

rr' C

rl Qr r'D H

c-I C~

IF HHILE EXECUTItlG TIIE I'OLLOHTNG STEPS TIIE RPV I'RTER LEVEL TRCHD REVERSES Ott RPV PRCSSURE CABIRI'tGES f(EGION, f(ETURi'I TO {STEP Cl-3).

"RPV PRESSURE AT IIIIICII LPCS SIIUTOFF }IERD IS RERCIIED.

+IIPCI OR RCIC LO1l PRESSURC ISOLRTION SETPOIHT, 1IIIICIIEVER IS I IIGIIER.

~

~

l jlel e Cl-4 t hrc Ugh Cl-8 refer to steps i@ contingency j-. 1.

There are tj;o critelia to be considered:

lj) Is i:ater level increas l.r: ov decreasing,

='rd 2) Is RPY pressure high, intermediate or loiv.

IT Ulhile executing one of thQ steps indicated, the RPY 'l",ater level trend revel ses or PPV j

c ssUl e reg'I Un changes a

l etul il to lie 1 og ic

i. 'b I Q Gi rQci

'hQ Qpel atol i he corvcct step.

Alsc, if RPV l ateT 1 evel dr ops be 1 oi i llc PiOS init',ation setpoint, the cpevator plevenTs autcmjatlc initiat On of PDS in order to maintain flexibility in copino i!ith tfe event.

The actioris n s;cps Cl-4 through Cl-8 ave summarized in Figul e 1 al'd ave discussed bel o<.

r.

C1-4 PPV lla':er Level Increasing, RPY Pvessuve Hiigh.

Tj:. step m vely tells the Operator to retuvn to the procedure developed freri the RPY contvol cuideline.

If the prcssure is hirh nd >;atev level

'.s increasing,

.he high prcssuve system(s) is providing sufficient irventory r.;akeup and tie operator L ill soon have to s.al't controlling r..-.keup f10~i tcj prevent h-'.s high pressuve syste-.s(s) from tripping off cn high i ater level.

0 Cl-5 FPY l'later Level Incrc.usii"g, RPY Pl'cssuve InterPediate If HPCI and RCIC are not available and RPY p"'essure is increasirg, e.;,evgency RPV GQpvessuvization s

reou-iveC.

This s becaUse no high prcssure systems are ave ilable and the pvessure l!ill probably ciet above the shutoff tjead fol i>l~atevev system is providiirg the riakeup if the vessel is not depressurized.

If the PPY pressure is decreasing ard rio l{PCI nor RCIC are available, then makeup is being provided by a lov(

pressu!.c system and a decrease

'.n pressure

<.i11 improve t!le makeup

I

capability.

There,ore, the operator returns to the procedure developed

,.rom the RPV ccn.rol Guideline.

Even if hPCI or RCIC are riot available and RPV pressure is not increasing, but i ater level is increasing the Gperatol aoa n retulns to the procedure developed from the RPY Control Guidelines.

If HPCI or PCIC are available, the operator permits the v,ater level to return to the low level scrar, setpoint and then returns to the procedure ceveloped

rom the RPV Con rol Guideline to control ii'ater level. in the noir

:al rance, o

Cl-6 RFV l<ater Level Increasing, RPV Pressure Lofti If RPV pressure is increasing, emergency RPV 4epressur',zation is required.

This is because loiv pressure systens are providirig the rakeup

<,hich is causing s;ater level tn increase.

1!hen their shutoi".f head is reach=d, injection ceases ar d the level ni11 start to drop.

If RPV prcssure is steady or decreasing, adequate makeup i!ill continue ard tl'e opera.or returns to the procedure developed from the RPV Control

'uid line.

o C'.-7 FPY! ater Level Decreasing, RPV Prcssure liigl! ol Intermediate fiPCI or RCIC <<re not operating, the operator restarts them.

These syster..s r.;ay reverse the diecrease in <iater level.

If no CRO purip is operating but 'at least

-:< o norr.al irection subsystems are lined up for injection v.'ith pu"::ps running, energency RPY

~

~

~

~

I

~

)

1

~

~ depressurization is required to al tow them to ir.-:ect. If a CPD sieve running, there is a possibility that the CRD I'ur;,p v:ould ve!crse the level decrease before the level reaches

.he top o: the active fuel in v>l~ich case emergency PPV del>ressuv'ization

<:ovid not be required (This

!.a the case A.t '.ng the Pv">ins Ferry five).

I!o<;ever, if no CPD pur:p is operating, there is no reason to delay emergency depvessurization until the i.'ater level reaches the top of the active fuel.

ro CPD pump is operating and ro normal in'ection subsystemis are 1'ned up Gr injection v;ith at least one pum. running:-tive operator s;arts pv,:ps ln rilternate injection subsystems

'I'!hich are lined up for injection.

lI:en RPV i(ater drcps to the top o" the active fuel:

'3)

If no svsteo, injection subsystem or alternate in-'ection subsystem is linec up i ith at least one pump running, steam cool'.r.g is requ',red (contingency

-,'3).

Stean cooling is only a temiporary measure to gain time to start an injection system.

Ti.erefore, i:hen any system, injection subsystem or altevna.e injec.ion subsystem is lined up s<ith at least one pump

'running, the operator returns to the locic diagram lo Ceto'iine;Ile apovopr'ate step.

")

Gthen;-i e,

m. vgency PPV depressuvization

's.recuired.

This allo';:s injection by lci.. pressure pumps.

o Cl-0 RPV !'ater Level Decreasing, RPV I.o<v If no core spvav subsystem is operating, the operato) start pur.ps in alternate

-injection suhsystei.s v:f.ich are lined up fov injection. If PPV cressure is incvoasinq, er.erjc'cy Rl V depvessur'.zation is reouired to

I

~

~

I

~

~ ke p the pressure low so that low pressure sisters s:ay iniect. If i;ater level drops to the top of act-'vc fuel, tl en core coo'>'.rc: >;ithout level restoraticn (contingencj 84) is required.

~ >

~

~

Car. 'Agency -.'", Erercencv RPY Oe ressurization Emelgel:cy PPY Deo c~urization is identified as being required at several steps in the Ccl tainment Col'.trol Guideline, at several s;eps ir:

Contingency

-,'1, 2nd "

tno steps in Contingencv

=,".7.

l h never Em roency RPV Depiessu>,'zatioll is re/I ired, pl"essure control s'."i'ches to Cont-', r.cency

'2.

i'!he ther bol GA i Agee t ion is not reoluired or boron -injection ',s required

't'lt 1 al 1 ir"'ection into the RPY excep':

rorrl boron in~ectic n systems and CRD blocked, several steps are tai:er. I::hich cuici:ly depre surize the reactor pressure vessel.

If ar. isolation condel',ser is available, it is in-:.tiated.

If SI:ppression pool Mater level is 2bcve the elevation of tcp o; the SRY discharoe device, the opelator opens all AOS valves.

If anJ AO val ve c2Anot be opened tile opel ator cpeAs othel SRYs ufiti1 ti'.e sar,"e nuf.ber of SRYs used for ADS (typically 7) are open.

This step silould depressurize the RPY to pressures I;:ithin the range nf lofti head pul",ps I;ithin three to five mir utes.

Further, if less ti;an the minimum number of SRYs reru'.red for emQI agency depressur izai.ioIi ( 'picalli 3) are open ard PPY pressul e is at least the I-,-;n';rlu!I: SRV re-opening pressure (typicaily 5n p"-ig) above su-';ression ciia...ber pressure, the opel'ator rapidly depl.essurizes

'.Ile RPY using ore or f..ol'e of the follo;,'ing systel!Is (used n crdPr

'l'Ih cii I"111 mll'iRlze I"aoloaci ive release to the environment):

o l!ain condenser, o

RHR (steam col'.densing mode),

c t!f:her s'.ears driven equipvent,

e I

~

p

~

~ o Hain steam line drains, c

HPCI steam line, o

RCIC steani line,'

Vead vent, n

Isolation condensev tube side veri-:..

Fov a typical BKR/4, the reactov can be depvessuvized quickly nith as TQ)" as th! ee Sl'Ys. If only cne SRY is ave ilable, it <.",'ll stil 1 depressurize the PPV but the t',r:e to depressurizo v.ill be much longer (on the order of 20 to 30 minutes).

Therefore additional vent paths i,ill be n ec'.ed.

The ma'.n condenser, if avallc.He is very effective; r.:;st of the other systeris listed are lc>> capacity but in combination may bc helpful.

I>

RPY floodirg is requived, the operator st'.tches to procedures developed fror! Contingency

.'6, PPY Flood irig once the veactol pressure vessel is depressuvized.

Othprhise, the operator veturns to proc'."cur es ceveloped from the RPV Control Cuideline once depressurizaiion is complete.

~

I

~

~

)P I:i

'3~t.

C Steam cool'.nc is called out in Cont',ncency

-'.I '.f while at erpiing to restore PPV water level, 1}

RPV water level is decreasing ard 2)

RPV pressure is high or iriterr.;ediate and, 3) l,'o

ystem, injection subs~ stem or alternaie injection subsystem is lined up with at, least one pump running and, 4)

RPV water level drops to the top of the active fuel.

8tatec! siriply, steam cooling is used when there are no systems injecting into the vessel Thi s cont'nc'ency provides cool irc; for an inicrim pericd awhile the plant staff attempts to start an injection system, and as soon as a system is injecting, the operator returns co the level desi.oiaticr, contingerc<<.

For steam ccolirg, the i!ater level is allo>.ed to decrease to the level i!hich corresponds to a maximum fuel cladding tenperature of 2000'F.

Cre SR / i 5 tlien opened to obtain steam cooling.

TIE s one valve i s he 1 d open until pressure drops below 700 psig; this limits peak claddil g tcriperature to 2200'F.

t'hen RPV pressure drops below 700 p.ig, all ADS va i Yes are opc ned to provide addi tlcnal steapl cool ing Once

-.he vessel

'.s Cepressurized, no add'.tiora',

steam cooling is possib'ie.

These actions arc based u ~on best estir,ate analyses.

I If no systems are injecting irto the vessel, stean cooling is the cnly optior'vailable.

A slight increase in core cooling tire can be ach'.eved by opening the SPVs cne at a tir..e, l:ut the additional cor'plication in proccCures is unwarranted.

Opening of'he SRVs one at a

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feU r.".vutes but recuires the opere tor 1 et'in at the SR / control panel during the stenm cool i Ag chase.

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I Ccntincency

-..4, Core Coolirc >lithout Level Pestorat on Cont-.'ngency

=.",4 s entered only from step CI-8, RPY i:ater losel Uecreasirg, PPV pressure low, of contingercy 81.

The spi ay rode of core cooling is established if PPV water level decreases below the top of the act i Ye fuel

'L hen thc, essel is depressurized.

In th is 1 ineup, a spray subsyster>

drai." suction Toom the suppression pool and sprays 5'c.ter ove1 the fuel irom spa eels li,ountcd inside the core shloud.

Tho watel then drains back to the suppressior.

pool through the break (if no brea!:, the core spray system i ill f1ood the core).

In this Harm r, long term cooling can be provided even tl:ough.he core cannot be flooded.

l hen conditions have improved such that RPY water level can be restored to the top of the active fuel, the operator v!ill terminate core spray and return to procedures developed from the RPY control Guideline lo contrcl level abcve the top cf the active fuel.

l Contiriaen~c;-".", Alternate Shutdcwn Coolinq Contingency 85 is entel'ed from the RPY Pressure control sec'ion of the RPV Control Guideline if; after stabilization of PPY water level, RPV cooldown is re(quired but caAnot be accQI plished Using norI"';a i sllUidown cool iI g 01'thnl pl essUre control svsteI:.s and all control rods are inserted beyond position G6.

The alternate shutdown cooling I ode is ir.practical for the case 0-a plant shutdown by boron because suppress-on pool water is cil culated through the reactor and boration of the supp!.ession pool would bc required to pl event d:lution of the boron in tl'.e core.

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1 The alternate shutdown cooling procedure Ier.:oves heat from the PPY by slcwly flooding the vessel until the I'ater level is above the level o

the main steam lines and the RPY is slightly pressurized; tl e I iniII:um rui"bel'f SRYs required (typica'.ly one) are opened to establish a flow path to the supp. ession peel.

Low pressure core spray or low pressure coolant injecticn is used to inject into tho vessel ard suction is from the suppression pcol.

Tie miniI':Um nvmbeI'f SRYs is selected to rlavimize tl:e driving ilc=d foal li'a er flow thlcuoll ".he SRYs yet Ila'IAtain RPY pressure below the point at I'hich

= s;:I:gle LPCS or i.PCI car deliver suf. icieri flow tc I'e;.;ove decay heat via liquid flow thrcugh the open SRYs.

Adecuate flow is defined to be the flow rate which 1'.mits the temperature r se within the core to 1CO'F for decay heat gene> ated ten mirutes after a scram from full power; this is a coAsevvative assumption for shutdown cooling.

The

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a I cl'te shUtcioNn cool ing r..ode is an acceptabl e r;.ears of cool ing the systen if normal rie~hocls are not available.

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~ Contingency 86, RPV Floodina Reactor p', essure vessel looding is required h'hen:

1)

RPV hater leve) cannot be detevnined, 2)

Dry)rell tempera.ure reaches the RPY saturation tei;.per'ature, 3)

Containment temperature react es the RPV satuvation tcmpcrature, or t))

Suppression chamber pressure cannot be maintained beloh the pvimary containment design pressure.

The flooding procedure depressurizes the RPV zrd slovlly fills the vessel us.I'g zny of a Lul be)'f spec'fied makeup systeI-.;s. - If >;-atev leve<

cannot be determined flooding Iray be ve)ified by monitoring the response of RPY pressure.

As in alternate shutdo);n, SRYS provide a

return path for flo)v to the suppression pool.

Three separat flooding methods are used in conting ncy

-.-",6.

Ii flGGding is necessavy

)<hen zll control

)'GCS zre not fully insev"ed, Step C6-2 is

'0110)'!ed.

If flooding is reouired because RPV );ater level cannot be cetemined, Step C6-3 is used.

If nzter level czn be dete)I)ined and all rods are fully insevted, Step C6-4 is used.

FG)" S ep C6-2, all irjection into the R.".'::cept fvo;I boron inj=ct.nn s'stems and CRD: is blocked to avoid

)Bvce pc).e) cxcui sions dL'e t0 co!d

< zter addition from ECC systei:I, ano 'ovon dilution.

Once RFV p!essure is beloi; the minimum alternate RPY flooding pressure, iniection is cor;.enced and sloi;ly increased to maintain pressure above

~he minimum alternate R?V flooding pvessuve.'he minimum altelnate RPV flooding

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In step C6-4, if suppression char.."er pressure e>.ceeds the prinary ccntainm>ent design pressure, floods:g is required to quench th>> source nf stean v hich is pressuriz-'ng the containr,: nt.

Th-:s;:s the only situat'.cn in the guidelines v.'hich requires flooding <;hen nate>

level can be deterrlined.

In this case, the opera or flcocs the vessel ard cor tinues flooding until prir.ary cnrtainri nt pressure is reduced.

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Cortincency 87, Level/Pnl!er Control injection is required ollol!irg a failure to scram.

Ccl'i.iligency 7 is to minimize heatup G

.he supprfssion pool during The objective.of Ccntingenc."7 is e"tered frcn Guideline RC/L or Ccntlngency

-"1 if bcron boron in ction.

f a reactor isolation does flot ac Gl..pa y a failure to scl al 1:

it 1 s unl it'.cly that Cof t";llgency i;.

'1"i 1 1 be entered.

Steam

<! ' l sifiply be discharged to the conde sel and no cor+airiment hea up l.ill occul.

If a reactor isol ation does occur, rel i e va1 ves nil 1 di scharge steal" tG the suppress icr; pool at a rate ecui vv 1 crit to ihe reactor power level.

Unless pol'er i'educe~i,

+lie SL'ppvessic~".

pcol heatup during tile boron in>ection 1'!il 1 be excessive.

Trippino the recircul ation pumps

.o reduce poi'er to natural circulatlcn levels

',s rot sufficient.

l hei efol e, the operatol'ecreases po'1'iel" bJ 1'educing the core flov! by lovering the <;ater level and thus reducing the natural circulation dl 1 v 1 ng lleac..

The opera ol lcl'ers PP1/ 1!ater level by terminating ard pre,enting al'njection if,:n the RPV except

-"rom boron -'nlect.on systems ard CPD until el ther 1

f:eactcr pol:er drops bein:: the APf',t'. dol;rscale t.rip, or 2)

RrPY 'vatE'1 level reaches i.mle top of active fuel, Gr 3)

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. 5,"',s 1 f'f'ain closed and dryl'el 1 prcssure refla'f s belo<'i the high c:.pl;ell pressure scrar. setpoin..

This miriimiizes the suppress.:on pool hea:up but also reduces ihe fl(vr belcli that recuired to rlix the bcron <!ith the 1;ater in thc vessel.

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a I; flo!! is dec..eased sufficiently to re(luce reacior pc!;er to the desired level, bo',on mixinc effiiciency is so, low tha" the borori s".~(nates

'.r. tl;e lc!.'er plenur,..

C!!ce the required ar.". urt of boro!

has been irected, core flo'cl!:";ust be increased to rapidliy distribute ihe Lolon tt;rou(.hout tl!e ccr This is accorplishe(I by

) a:.sing PP'l!!ater level urti.'natural ci! Culatio!i f ~ o!".'s !ee"tablished (reel! cula.iion pulips ca!'i!'c't be u"c(.

beczi:-:.-. ~f the lc!'. PPV!vater level. interlock, desigre(I to prevent cav

).

Test data indicate thai sufficient'oron liiixing!!illoccur cs

.iiu >;ater level increases.

L'ecreasirg the

! ater level to the tcp of the ac'ive fuel nay result in large flo!v oscillations acccrpanied by p<<!!ei oscilletio!!s and!!ater le"el oscillaticrs.

The effects of these oscillaticns Gn the Uel rods is unkro;;n.

I~o;;ever, lc! ering the!va~er level to!educe po!;e! is necessary to vininize pcol hcatup Lecause:

1) If !IPCI (or IIPCS) and f'.CIC are u ed to I:cep tie '!'atel level above tlie top of tl!e ac.ive fuel, er;:ergcncy RPV dei;ressurizaticn

<.'i11 be rcouired to preven. e"cecding the I'eac capacity ter,'porature lir!itof the suppressior, pool, 2)

HPCI 2nd RCIC taI;e suction fron the cordersate storage tank iriitiallybut l.ave to s"'i ccl' sucticl

~ froll the sup) ressior eccl af"er abcu.

20 r!in!!tes.

As the pool I!eats !.'p, I;FCI and fiCIC i.:ill possibly be losl c! 'o bea

! 'g and !c!,'"essure sister!s!"i!1 be recuir~'d to inject.

The steps outlined in Cortingency

."'7 to red:ce poi:,er by dropping!!ater level to the top of the active fuel are contra! y to noriial operator response and have the poten.

e.l to p!.oduce so!re claddirig fa".!!re as a

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Conclusions 1!e h..:>> revie;>ed the Bl.'R Energenc I-'rocedure Puidelines and find ther. to be corditicnally accep+able:

There are tt;o situations, coribustible gas controt and secondary containm nt control tvhich have not yet been covered.

These r.:Us ~ be covered

.n subset;l'el t revisions to the guidelres.

There are also a fet'ections in the guidelines t.'hich require rore Mork.

These incluoe:

1)

Criteria for defining conta innent venting prcsst!re need to be deterr;:ined, 2)

Con servatisns in the deterred',nation of. orywe11 spray floral rate need to be reduced, 3)

The RPV flooding contingercy needs o be revised to t-.,at:e the depressurization s.ep r';ore explicit.

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'.> these e,".ceptions, t' find the gu i del ines to be acceptab i e.

!m;:le;:entation c f procedures based on the cuidelines nay proceed before these concerns a> c corrected.

Because 'e Bl R Owne; s'roup I ay disband a,ter these guidelines are

approved, there

',s a reed for a group consisting of Gl.R ot.ners ar.d Genera'.

Flectrio to co!Aplete the dpvelopt".:ent of the gtlidel ines and i.o I'i in a in +he gv ieel ines aft'cr develop-;.c.nt is cot":,pl cte.

The deve! opment of the gt'.idelines ray be con" ordered corplete after cori us;ible gas control and secondal y conte'inl;beni con ro I gui eel nes al e r8v iev.'ed and approved.

Vaintenance t ovid inc1ude incorporation of'pera ing experience ard nen knotriedge into the guidelines and rodification of the guidelines to accnun; for net( equ'prent.

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