Regulatory Guide 1.27

Ultimate Heat Sink for Nuclear Power Plants

ML13038A084
Person / Time
Issue date:	03/31/1974
From:	US Atomic Energy Commission (AEC)
To:
References
RG-1.027, Rev. 1
Download: ML13038A084 (4)

-REGULATORYýGUIDE:1.27

_UT1MA~TE'H

EAT S!NK A. ;NTOUT~-General -De Appendix A,"1~50, M'IJicensing.requires, in part"~Cooling

'Water" of na. ' "to l'O:CFR'Part'

tiization Facilotns,"

e:.:to assure -that sits ,Iec"unJt'acc*the Ind; ,co IWithst)ss , of it:equIesý

I: .pan, LlUnI tures, onenLs _important to safety ibe I the:,effects

?of 'natural 'phenomena pability 'to -perform their "safety"describes~>a basis acceptable to t'he*snuiaiown cc ,one untW :the that accidei*shutdowni .a.ma'intaini'all'

nts. The Advisory -Cuminittee on R~.eactor has been consulited concelrnginghis guide and-ed imithe fegulatory~position.-itiy or.'the sink- sho ,p'ovide'ýe66liitabot hafor the pefio'oevaluateithce sjtuatinand for, the p to take' corrective action. A p ej considered- to be adequate -. or'addition:

-.roceCur es shoild 'be-avai]RB: i]l lter -s,ýstenvz1s Mnat compiex' oi ~waLT .':Sources', necessary retainiing

'ýstiuctures (e.g.,, a "pond m4; or -a river- with its'idam)

-and the canals.or nnecting the sources ,with.but'

not including, water system intak-structure

& 'for -a -nuclear'tL, f coolinrg towersor tfereof -are cnai -a -lu-cdy. suvvly'M w t'cl -IýS eeabd design bisis 'temperatuires of "safet/y-rel

'are not exceeded.-FoT

heat sinks where ,be timited anid/or 'the len peyrat'uireof'I"from 'the sink becmy bcrjcitic;abje~j

'capability

'of the'-tAing into accoL ecuiniment and li ions.

'hesinik safety on "mybetpfovided by ',Where -'ti'rf ziyflda functions~~~~

~ my b he-anIs or'cndiuits are require;aIprt ,bflhe ru iaural or ýman made 'features More one water .sinkrat-east Two only one source -may be involved, in the ultimate, ýheat sinki source of water has been demonstrated'to-be ade'quate;

'complex,;in performfingithese functions -However, -iisingle canal may be-acceptable ift.s.....isfies.......

conditions, Because of* the" ýimportance

'of ýthe sinkto- The four conditions above. Where the sink i clu~des; -orthese functions should be asured during and than ýone source of water ndividmuaatefi:so-rc

-.es'foillowingAhe-mnostsevere natural phenomnaempostulated may have -different des'ign requiremen'ts.',Mulitipwater'w Sfor,.te :siteýi(e~g the'-.safe

ýshutdown, earthquake, ,design -sources, including their associated x iretaining sui urs 6'basis-'totnado

'hurifiane,,flood, or diought?ý).

ln addition'

--and'required canals ýand' conduits, shoul~d~bese'

_'rated, ~'thc~sifk safety functions

ýshould'be assured,ýuriing ot~her -and-protected so-thatfailure of-any-one--wýillntndc applicable stread vnsta my-b-cue'by failure -n.zany 'other 'that woudld- pred~udeitauoomphishing natural phenom'na such as river blockage;.

river the safdctfunctions of the The;c compiex 1(ibut not d ivex'ýsion or'rreservoli depletion, or if applicable, other -necessarily its individialj/ea-tiuý.S)

rust Jberca0Able of accidents such a.s'transportation-accidentsrinvolving ship. withstandii eac -of th 'm~'e iat iral, phenmena'collisions.

airplane.

crashes, or -oil .spills .-and fires. -'expected, otlher s-ite-rielat-ed .evenrts, reasonable

6 R, a. combntieo o-s -of :less sever6;_atura1

ý'anL- -:coibina ions of rnaturalj nomena.and

/ior.ýste-.relatd.etI.,l

.acn ,or -. e nts;, :nd- a .bu le failure' of ; ,man ae stmact.ural-.

.... -,*.onider-d extent, needed fora-consistent, vel'of' $features y'ossof -, 0 capability of -the sirik 'to -conservitism;

for ýexaniple, -such- coijibinat-jons should be. -accompilish -its.,- safety -functions.-

'The. rmostl isevere-evlntý ~iics~ilee1e'rbbiro-hieitn phenomena .may be' considered rto occur undepen dently at

'haiing -ignifcariit consequences is- and -not simultaneouslyv.lnaddition the minglefafilure&of

-., comparabie to that associated wi -the most --severe .-.man-made st'r-uctural features need not be c'onsidCeedALo

-phenomena..-

occur-sirnuiltaneously with severe natural phenomena orTh fe;h tld'bea -high 'level ~o~f ýassurance

1that:the--sieeledvnt, --.. waterces<

of the Willbe'availableht hen'needed, .For -example, it,-would be acceptabeif Water'Soure"'....

For 'natural ,sources.historical experienrceindicates'that

-.No. -. I (say a man-made pond with a dam) and'river blockage or :diversion may -be', possible, as well as connecting conduit -were capable.of withstanding thc changes'in

-,ocean ior lake levels as -a result -of -severe safeeshutdown earthquake, tornado, and drought and -'inalural :.events.

For 'man-made .portions, pa

r. ticularly

'Water ,SourdceNo..2

2(say -3 river-With an: existing dam)structures

'above 'ground, failures -are -not uncommon.

and its-connecting conduit w ere ýcapable-,oof:withstznlding

,ýtýýBecause of ýthese fatos cosdrto'hudb~ie the 'probable.

maximium flood -,How Ahe , tlecomiplex~as

4theksjiiik

6cmprisi1g-t r ' *aaewhoue

'mustachalso

-,be cpable:, of hsandiii;

an 0,igtteast.ýtwoý,a- asucee wwieinut.

tc d-fny':-kcJ fp fonk~fn fnls it -a-reasobf probable" zorfiibination

~ofntir]o',,can 'bdemonstrated'-hit there is an ictremelyi l owv phenomena .without loss of the sinik'probability of losing ~ the capabilitiy

of a sinle source functions.-For 'thotse -cases in:-whichlan believes a single S, waiter source -may be acceptable it should be The ultimate heat sink, as a -comp]ex, should be demostated that the source can withstand, without shown to be highly reliable' ,t shig nnh tger:howi g haý,Crti S- -- lo~ss ~ofrthe ssink~ safety functions -the following -events: -'conditions -are satisfied.

'For- .example, x onsideritWater- s¢: e~fai vere, atura mhenomiena .efaected, ta.ken, ,Source Noa -satbove 'Such i) .. .:~~~~ ~~.site-,Teiated eins' at~hve .thie river canLnotbdvetdo4lke ufcnlyt 7-ocd ;ibed or-tht.- i nay ocu uigt e p ,tlf a ,' affect the availability ofv-water at the connecting reasonably -Probable, combinations of less severe ýnatural conduits;

(2) no, serious ýtransportation -accidents, have-pheno mena :and/or sile-related events, and"(4)--a single occurred-or canbe reasonably expected-, and (3) the dam -failuieof, man-made Struct-ural features. -In applying this- a "s designed to appropriately conservative requirements."single ýfailure, various mechanistic failure modes 'has functioned properly over, it-s lifetimrel, and (balsed oln h -.be-hpostulated -One may choose assume a oprojectn te b will fnction v ... i~e-asum8 owveosa s, but ths sntnecessaf!

eu ...... Phe. -ohnp~iayo.

tt suce o ee'colb !bnt-:tsAsoi i.-' ' properly -for the Aifetimeonof- the ~nncleor

i. powero

..its it ":re qir 6i iiw h..neuneso

~otua , _serves. -Compliance with~ 'these, conditions wouldý ino r-'ma4~~ratue o-~- d 6diin i -hixeitd ioever,-remo-61th'neediforf another sour ce D oloIng.- -ffect of forces in~mne :tthe ti e of riip'ture)

should water if a' sigefiueotedmcudr'lýi'oiv-be assurnedý

however, 'it is notr-'ecessar-ily.

required that the coln 'iait fti, uco wt el one. assume th dan iitgrates instant'aneously with- constructed-features, not ~required to ýbe desingedt A'total>-Is offnto---s-nte eapethe withstand

'the safe' shutdown earthquake or the -Probable'

--consequences of a postulated slide of earthen canal walls maximum -flood ,shotild at -least, 'be designed- and- ': should' be assuredL;

however, it is not necessarily constructed to withstand;,the effects of the maximum rrequxe!ire at~ba neý assume wate~r~fow ceases ,completely, , .earthquake'deterri-mined~oti -the basis of historic seisnCity-~

1'. 7-: :

• b : " :.A gf , .& ,' .,: , ; ..= "5: " " .; , :: f : '"' = : , ': , ,r: .j a- -fi'7 iea&WtTfo bsdon~'everehiistorical events in4ihe ýregicn. in:~Ihe :importance of -the sink to safety-is such that, if, r during plant operation, the -cappability ok the .si -is" ,iiretened,:

as- for example 4t6 permit riecessary maintenance or as a result of damage, restrictions should-be p -lLaced on plant operation.-

The -technidal

'specificafio'ns'-should statae'Thea -c ti ons Io-b etakeni in the* event ,-.thc-,.,required capability -of -tfie--srik is -temporarily unavailable during ;plant ;operation.

For example, the Atechnical s pecifications.

should require-, that (1) theýClommission

'be -notified-Af the sinkd does -not satisfy -the liniiting conditioni for -opetation-and,(2)-if its capability cannot be restoredto- this condition,.within z reasonable.period oftime, all- units- served:by the sink -L -hut down;{7:-....and--emainshut ,a; donunfil:this ctap~biliti:

is-,x es tore d.-C. REGULATORY

POSITION 1. The ualtimate bheat sink should -ýbe capable 'of.providing'

sufficient -cooling for at, least :30 days '(a) to permit simultaneous safe shutdown and cooldown of all nuclea-reactor units that it Serves and to maintain'them in, aý'.ife:shutdown -condition and- Of an-;accdent, imnc'uie, uii~t:;tolimit tbe -e'ffectý

oftha-ajccidu~nf y, ,to 'errhiit simultarcous and safeshutdown ofe remaining -units, sand to maintain them in a safe shutdown.aondition-.-procedures .for:assuringa continued,

30.days should~beavailable.

i speeds 'occurring'

sirmltaneously results in the-maximum-amourjt -f-evaporafio nand drift loss.b. -Analysis-of-the temperature problem should use -the ýworst I- -day and -w'orst- 30-day .'periods of meteorological record in -the region .tre :ulting in rniriimum

' -heat'transfer to .the- atmosphere"and maximum plant intake -temiperature.

..urthe',. 'thewos l-y-period ofrecod-Soud~hld- be assumred'tb Te-the fiksday CI f-the worst .30-day :period -of ',record.

For'transient temperature -analysis, diurnal variations

-.intemperature should :be used fo6r the 1-day and 30-day periods' of analysis.

These -variations are readily- estimated:

from'local-,weather;,-r~ecord~s.

App~tlicants -should-1be

assufredthat either a-normal-oreniergency shutdown during theý worst--1-day and 30-day period -;of -record will not iresult in plant intake water temperatures-'exceeding Aesin basis tem peratures.--

---The above -analysis related .to 'the,30-day cooling --supply .and .the tempnerature should 'include--sufficient

'information

',to 'substantiate t'he- assumrpt'ions- and-analytical -methods used- hismnformation should,-include'

actual, erformance

ýdata -for a'siiriil4),coiluing K-mnethod:operating

'under-load

ýnear rthe specifi:deSg

"...~conditions,-or justification, that-- conserva-tive -drift 'loss-ri:d'" heat transfer viues'h

,,'eb'eni used. , --:-A co6ling capacity.

of less than 30 days may be acceptable if-it -can' be:.demonstrated

that,, replenisiiment:

.-~f =e n" O LL~1~gLm W 4Lr, I .:.u.pp1y. -can oe,-" 'erJrecr5o-to, --"" .....c.ent 'conservatism shouldbe provided to assure assure the 'continuous~capabili' the- *in ito -perfor'..

'that a 30-day- cooling supily is -available and that design .its ,s- et-y-functi iinto, i theo nt;t e avabilit yte-mperat f 'sfety--'elated,:equipment are -not -of replenishi ent.equipment'and

'limitations that may be" exceeed.'

' -l-Fr "heat, sinks where -the iipply Vmay', be --imposed on Treedom of--,.movement" .followng an limited and/or the 'temperature of plant intake -water accident or-the occurrence of severenatural phenomena.

-from the sink may eventually become- critical (. -..-cooling -towers, -or --other' sinks -where -2. 'The ultimate'heat-sink complex, -whether composed Srecirculation between 1lant .cooling and ' -.ofsingbeTormultiple water.,-sources, shouldbe intake -can occur), transient analyses -of.supply-and/or withstanding, without loss of sink-, saet functpnof

" te: emperature should be-performed.

using the folowing:

specified in regulatory

.position C I, the following

--'- " ' --,events'.

-at., A~nalysis sup-porting

'the a,. -vailabi.ity of a 30-day -cool ing. should be: based. oii a. The most severe natural phenomena expected measurements combining the -worst irecorded

30-day takei individually, average) of maxlinumrdifference -between -" dry , temperature and .dewpoint

..temerature,.

AT, -- -b. -The -site-related- events' .(eg:, transportation

-!.and .the..ihest wind speeds recorded during the same accident, river-diversion) historically have ocdutrredý, 2.30-day ~period ýsuch-Ahat the combination of IoT and, orhat may'occurduring the-plant-lifetime, ........... ... ..eas na.ly .. 'able --combinations

'of less, nds,..&. se' r naturalphenomena

2ndfor-site-related events, Mayi "be-madc, analytical -techniques andicomputer S-' prgams ",Contained iq "Generic Emergency- Cooling Pond ." , Analy'sis,--"COO 2224-1 May'1972 -October 1972,preparedfor

--d.. -A single -failure of man-made struct ural -'the' USAEC by :Uni'ersity of Pennsylvainia, School of features..Engiee-in.and App-lited Science, Civil Engineering, Philadelphia,--

719I04- For sinks other than-small shallow nooling -3.* The -ultimate iheat .sink.should consist of a least two' --D mnuaransien. .analyses, should.,:be performed to sources of.water,, including-their--retaining st~uctures

1 -ýýde ion d/ortm'imor, ' "u mrnintakewater.

-,eacl-,w th the',cp~abiity -to perform the safety fn ct-ions -'spcfe-i reuator~yposition- C.-l. above, rýitcT-I. -' -p,. ---~ I- -'----------------------

31 -

DC GcmtM 0 Sta ed that thicm is an extremcly

'low ptobability of losbig -,ie capabilhtytof -i single source.fci'her should be a lattwo aqueducts connecting the SOurce('s)4.'ith thc intake structures of the-nuclear power u.nts, unless. it cqan be demonstrated that 'Ihere ..is an c~treme~ly'ow probabilityvthat'a ,singleaqueduct can faIil entirelv-'ýs a'T6 Wi of natra peioea.1,Iwae sorces and their Lassuyciated aqueductSs hiouldb b-highfly diaie ndsholdbc separ-ated and pro tected~such'

that failure of any one1will not inducefaihiueof.t

4. The technical.:specifjica;tiofs include ,provisions for actions :to:th

a. conditions

4hrea~ten:

pýt i~dgil Ibe- Wi-niate, heat..sink or -IllieIsatisfy reg ulat ory. posit ions i:C..f-operation.'

~';' p'..-. ~ A, i,%5 * : I I': -'?i!