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Vol.1981/0156

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COMMISSION OFTHEEUROPEAN COMMUNITIES
COM(81)519 final
Brussels ,23September 1981
H
COMMUNICATION FROM THECOMMISSION TOTHECOUNCIL ,
s ■
Safety Principles forLight -Water -Reactor Nuclear Power Plants'
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C0M(81 )519final ,1-
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Û2TYY\
X.
FOREWORD
TheCouncilResolution of22July1975onthetechnological problems of -
nuclearsafetyforesees theCommunity actioninrespectoftheprogres­
siveharmonization ofsafety ^requirements andcriteriatoproceedin
threestages.•f ...v
Thefirststageistheexchange ofinformation andthelistingofthe
methodologies ,criteria andstandards appliedinthedifferent Member
States.Thishasbeenlargelycompleted ,eventhoughitisnecessary
toreviseperiodically theestablished inventories inordertotake
intoaccounttheevolutionary character oftechnological problems of
nuclearsafety.
Thesecohdstage'consists inidentifying thesimilarities anddissi- '
milarities andinanalysing reasonsfortheirexistence .
Theaimofthethirdstageisthe^establishment ofRecommendations
pursuanttoArticle124secondindentoftheEuratomTreaty.
Duringtheworkrelating tothefirstandsecondstagesmentioned above
conducted withintheWorking Grotjponsafetyof'lightwaterreactors
"Methodology ,criteria,codesanjdstandards "withtheactivecollabo-
.L1:f
rationoftherepresentatives fromregulatory bodies,licensing'
authorities and/orassociated safetyandcontrolorganizations ,..-
utilitiesandequipment vendors,itappearedthatanyspecific harmoni-:N.
zationcanonlybebasedonapreviousharmonization effortonthe ■-
'basicprinciples ,ofsafety,onwhichrequirements andcriteriadeoend.
ATaskForcewassetup,composed ofexpertsfromthenational safety
y? ..-:_..;-'=authorities andsupported bytl\ecompetent services oftheCommission ,
tocompileasetofbasicsafetyprinciples :aridaschemeforsubsequent
requirements andcriteriafor'Wght waterreactornuclearpowerplants,wjiich
may,ingeneral,alsobeapplied'toothertypesofnuclearpowerstations.
•..!''■. ■■ : .·.
' ■ •;iv" •i .■ ■
." .K'': -kV''-■: "./.
- . ^ %i: -v'•'.....■'
j!l.■■il ' ', .!' '

II.
The result ofthis task isgiven inthepresent document which was
formally approved bytheCommission andwhich isbrought tothe
knowledge oftheother Community institutions andthepublic .
With this document theCommission makes known thebasic safety principles
for light water reactor nuclear power plants interms which caneasily
beunderstood and replies tothemounting emphasis andattention to
safety bynuclear industry ,regulatory bodies ,andbythepublic atlarge .
These basic principles /constituting thefundamental andgeneral .
safety principles ,form anentity .Though general innature ,they shall
make acontribution tothethinking intheMember States and theCommunity
institutions onproblems regarding light water reactor safety andin
particular are intended toform the framework which can beused as
■' ' 1 - r •
reference forjudgments that musti bemade inthesafety evaluation
process byregulatory bodies ,licensing authorities ,utilities ,equipment
vendors ,architect engineers etc',toadopt aconsistent anduniform
? 11 •
approach . ...y
This document will form thebasis forfurther harmonization activities .

1.
Introduction .
Mosthumanactivitiespresentapotentialhazardto
thehealthandsafetyofindividuals andofsocietyasawhole.
Ingeneraltermsitcanbesaidthatthelargerthepotential
consequences ofahazardouseventthegreatertheeffortofman
andsocietytoreducetheprobabilityoftheeventandtolimitits'
'consequences ... ;-
Thepeacefulusesofnuclearenergyhavebeendevelopedfromthe
beginningwithspecialconcernforprotectionagainstrisks,that
iswithparticularattentiontothepreventionofaccidentsandthe
flimitationofadverseconsequence^.
.Suchconcerncouldnotfailtobd,oiinterestatCommuninitylevel,-
anditcanbefoundindifferentReticlesoftheEuratomTreaty'and
alsointheCouncil.ResolutionoS.July22,1975,ontechnological
problemsofnuclearsafety..In-thelightofthisresolution
activitieshavebeendeveloped,inparticularwithrespectto
progressive harmonization ofsafetyrequirements andcriteria.
Inthiscontextonecanmakethefollowingobservations .: _
"aharmonization ofrequirements andcriteria^althoughpossibleat
-certainlevels,isnotpracticableatalllevels,becauserequirements ,
andcriteriaoftenrefer,forexample,toaspecificaspectofa
protectivefunction,whichmaybeachievedindifferentways;
-anyharmonization canonlybebasedonapreviouseffort .,
.ofharmonization offundamental ,principlesofsafety,onwhichthe
requirements andcriteriadepend;J–
-althoughtheaimistoachieveanequivalent 1andsatisfactory degree
ofprotectionofthepopulation andoftheenvironment ,'theway
toobtainthisdegreeofprotection maydifferfromcountryto
.country * ,,
Thebasicprinciples,however*must.andcanbecommon,
asfarastheyreflectobjectivesbutnotthewaytoreachthem.
' '• . t'•
r■ fli' ;

2.
The p.inc ;pits given herein are ofageneral nature und for the use of
designers .-operators and assessors .
The harmonization ofsafety principles ,require icnts and/orcriteria ,
even though desirable ,isnot sufficient toguarantee the harmoni­
zation ofthe levels ofsafety .Inaddition the sole application of
technical aspects does not guarantee the safety ofanuclear installa­
tion ifitisnot accompanied bycomplete and detailed assessments
coupled with appropriate inspection andenforcement activities .
Nevertheless the harmonization ofbasic (fundamental and general safety )
principles isthe necessary starting point for any further harmonization .
Purpose and scope ofthe document .
Thedescribed principles inthis document are divided into two
categories .The first category gives the fundamental safety principles
upon which the second category isbased .
.■α.
This second category gives the general safety principles to
achieve the objectives asgiven inthe first category i.e. toavoid
accidertts and tolimit the radiological consequences ofthe operation
ofthe nuclear power plant during alloperational states and
accident conditions .^
The document includes athird part ,giving alist ofsubjects in
which safety requirements might beworked out inorder tofulfill
thegeneral safety principles asgiven inthe second part .
1)„ .. .See definitions inAppendix

Fromthe_introduction itwillbeclearthatitisnottheintention
toimposethewaysinwhichtheobjectives shouldbeattained.Neither
isittheintentiontostatetherequirements whichmightbexorkedout
atanappropriate timeinanappropriate sequencesinceitisnecessary
totakeintoaccountthedifficulties inharmonization .
TheprinciplesgiveninthisdocumentrefertoLWRNuclear-PowerPlants
thoughtheymay,ingeneral,beappliedtoother„typesofnuclear^power
plants., ~ -.i,.: "-:>■ :AIL: '
Remark;Theuseoftechnical |t§E;mswhichareofspecialcharacter
orthemeaningofwhichhastcj'specifiedwasreducedto.aminimumin
thisdocument.However,forrdertainexpressionsitseemedtobeneces­
sarytoprovidedefinitions (seeappendix).Definitions weretakenfrom
*theCodesofPracticeoftheIAEASafetySecies50.;
PARTI i;
-ίίΡ''V.''■'.'
'Fundamental safetyprincipies . i,
1.Nuclearpowerplantsshallbesited,designed *constructed ,
tested,operated,anddecommissioned soastoprovide -
reasonable assurance •thereisnounduerisktotheworkers,
thegeneralpublicandtheenvironment .
Inthisdocumentonlytheradiological aspects,relatedtohuman-health
willbeconsidered ;noguidanceisgivenonenvironmental aspectssuchas
protectionofnatural,agricultural .andindustrial ,environment anciIuman
habitat;neitherisspecificreferencemadetositeselectionprinciples
eventhough,inthecomplexareaofsiting,exchangeofinformation is
goingonintheframeofCommunityactivities *
'''"'''
IAEA»International iAtomicEnergyAgency-Vienna

4.
Thecharacteristic hazardofanuclearpowerplanthasitsoriginin
theamountofradioactive productspresentintheplant.
Harmtomanmayarisefromionisingradiationsemittedfromradioactive
materialstakenintothebodybyinhalation andbyingestionandalso
fromexternalradiation .
Therefore
2.Measuresshallbetakentoensurethatradioactive materials
whicharepresentintheinstallations areconfinedinan
appropriate manner.
3.Thereleaseofradioactive materialsshallbeaslowasreasonably
achievable . .
' •[
4.Adequatestepsshallbetakeninthe^design,operation and
decommissioning oftheplanttoensurethatallexposures
toionisingradiations areaslowasreasonably achievable .
Theforegoingprinciples areprimarily aimedatnormaloperationof
theplant(includingwastehandling),butarealsoapplicableto
•accidentconditions .
Duringnormaloperationofanuclearpowerplantsomeradiation
exposureofsitepersonnel andmembersofthepublicisunavoidable .
Somedischargeofradioactivity ingaseousorliquidformwilltakeplace
andthisresultsinanexposurepathwaytothepublic.Thedosesfrom
dischargesofradioactivityduringnormaloperationofaNPPcanhowever
bekept,verylowwhenappropriate provisionsareapplied.
Inadditionsafeoperationoftheplantrequiresaproperlevelof
supervision ,includinginspectionssmaintenance ,.,-wastetreatment,and
repairwochwbichgiv®risetoradiationexposuretositepersonnel ..

s.
Consequently ,thefollowingprotectionprincipleapplies,inagreement
withtheEuratomdirectiveonradiationprotection andwiththerecom-
*mendations oftheI.C.R.P. :
5*Individualdosesshallalwaysbekeptwithinprescribedlimits.
Inadditionindividual andcollective dosestobothsite
personnelandthegeneralpublicshallbe.keptaslowas
reasonablyachievable .inalloperational statesofthe
4nuclearpowerplant.(
' .it-Itisimportanttotakeintoaccounttherelationship betweenthedose
tositepersonnelandthattothegeneralpublic.
Note:
Inordertodeterminewhetherareductionindo1sebelowthe
recommended limitsis"reasonably achievable "itisnecessaryto
considerontheonehandtheincreaseinbenefitfromsuchareduction
andontheothertheincreaseincost(social&ndeconomical )involved
initsachievement.AccordingtotheICRPanOptimum ^isobtainedata
valueofthecollectivedosesuchthattheincreaseincostofprotec_
tionperunitdoseequivalentbalancesthereductionofdetrimentper
unitdose(ICRP26,pa74).-
Theapplication oftherecommended optimization processisnotat
thestage,wherecommonquantitative limitsforcollective dosacan-
begiven.
* ' .'' :
Theprevention ofaccidents and,sinceacciderttsmightnevertheless
occur,themitigationoftheirconsequences arebothoffurda-^ntal
importance.Themoreseriousthepotentialconsequences ofaccidents,
themorestringenttherequirements willbetopreventthevaults
leadingtosuchaccidents.Furthermore theseOccidentswillrequire
extensiveprotective measurestoconfinetheradioactive produ;is.
Thisleadstothefollowingprinciples :
//
6.All'reasonablypracticable stepsshallltakento
accidents. . lui
International CommisiononRadiologica!Protectiòn *
Γ

6.
7.Allreasonablypracticable stepsshallbetakentominimize
theradiological consequences tothegeneralpublicofany
accident,shoulditoccur.
8.Allreasonablypracticable stepsshallbetakento
minimizetheradiological consequences tositepersonnel
ofanyaccident,shoulditoccur.
9.Themoreseriousthepotentialconsequences ofanaccident,
thesmallershouldbetheprobability ofitsoccurrence .
Toguaranteethatallpracticable stepscanbetakenbythesitepersonnel
togetanaccidentsituationundercontrolandtc?carryoutallnecessary
actionstolimittheconsequences ofaccidents,itisrequiredthat
provisionsaremadetoprotectthesepersonnelagainstexcessiveradiation
doses.
Therefore
«
10.Provisionsshallbemadetopreventtheexposureofsite
personnelreachinglevelswhichhampertheactionsnecessary
tomitigatetheconsequences ofanaccident.
Additional remarksconcerning theaboveprinciples :
Withrespecttotheimplementation oftheaboveprinciples 1,3,4and
5guidanceisfoundintheEuratomDirectiveoftheCouncil"BasicSafety
StandardsfortheHealthProtectionofthegeneralpublicandworkers
*againstthedangersofIonizingRadiation",15July1980andin
the"Recommendations oftheI.C.R.P.".
Doselimitsforworkersandthegeneralpublicfo?rcontrollable exposures
areprescribed forinstanceinArticles 7to13oftheabovementioned
Be-sicCafe'ryStandards.Inaddition,Article6requiresthatexposures
mustbekeptaslowasreasonablyachievable .TheICRPrecommends forthe
ALARAprinc optimization processonthebasisofacost-benefit
analysis.
0.J

7.
DerivingfromtheICRPrecoirihiendations itisadvisablethatalready
intheplanningstageofnuclearplantstheaspectofindividual-
annualdosesandsitepersonneldosedistribution aretakeninto-
account. *
Guidanceontheimplementation ofprinciples 6,7'*"®an^10is
giveninPartIIwithspecialreferencetoa"defenseindepth"
concept.Concerningtheprobabilisticaspectsthatareconnected
withptinciple 9thefollowingcanbestated:
■--;s'
'i->.■' -Riskconsiderations combiningprobabilities ofincident/accident
'··'"'»λ
situations andrespective consequences ,mainlyradiological ,havenot
beenintroducedgenerallyintothelicensingprocedure.First
approachesinthisdirectionhave,however,beenmadeandan
exampleinthisrespectderived ,fromtheseapproachesisgivenin
theAppendixtoPartI.,Themainemphasisoftheseapproachesisaimed
atcategorizing eventsinregardtofrequencies andconsequences
ofeventsandfaultsequences.;
Theschemewhichispresentedinthisappendix ionlygivesageneral
ideaofcategorizing eventsandfaultsequences.Categorization
inamorequantitative mannercanbemadeup,whenstillmoreinfor­
mationonthefrequencyandconsequences oftheseeventsandfault
sequencesisavailable. ~
tv

APPENDIXtoPartI.
Events(operational occurrences )withmoderatefrequency ,any
ofwhichmayoccurineverynuclearpowerplantseveraltimes
duringplantlife.Duetothepresenceofprotective meansin
theplant,theseeventsdonotescalateintosituations where
theprescribedyearlydoselimits {operationallimits)areexcee­
ded,althoughduringshortperiodsoftimethenormalexposure
levelsmightbeexceeded.
Examplesofpostulatedeventsare:
.lossofnormalfeedwater
partiallossofcorecoolantflow
.totallossofloadand/orturbinetrip
.lossofoff-sitepower. hi
Eventsorfaultsequences,anyoneofwhich!mayoccurduringthe
lifetimeofaparticularplant.Duetothepresenceofprotective
meansintheplant,theseeventsorfaultsequences arenot
expectedtoescalateintosituations whereexternalcountermeasures
to.protectthepublicarenecessaryotherthanforinstanceona
precautionary basisamonitoring program (withrespecttofood
stuffs),althoughtheprescribedyearlydoselimitsfornormal
operationmightbeexceeded.
Anexampleofpostulatedeventist
.loasofprimaryreactorcoolantfromasmallrupturedpipe
ofsuchanextentastopravartnorma],reactorshutdownand
cooldown,assumingmaKeupisprovidedbynormalmakeup
only. r

3.Eventsorfaultsequencesnotexpectedtooccurduring£he
life-timeofa'particularplant,butwhoseoccurrenceisnever­
thelessconsidered inthedesign.
Duetothepresenceofprotectivemeansintheplant,these
eventsorfaultsequencesarenotexpectedtoescalateinto
situations whereextensiveoff-sitecountermeasures are
requiredtoprotectthepublic.
... \•
Anexampleofpostulatedeventis:
.doubleendedbreakofalargepipeintheprimarypressure
-boundary.
4.Hypothetical eventsorfaultsequenceswithaveryremote
probability whoseoccurrenceisnotconsidered inthedesign.
Thesesituationsmightrequireextendedcountermeasures
•- –
toprotect ,thepublic,basedonanemergencyplanningscheme.

10.
PARTII
Generalsafetyprinciples .
Inordertoprotectmanandhisenvironment againsttheharmfuleffects
ofionizingradiation,thenuclearpowerplantshallbedesigned,
constructed ,testedandoperatedaccordingtoanumberofsafetyprinci­
ples.Itisofprimeimportance tominimizethereleaseandpreventthe
escapeofradioactive materialsinalloperational statesandduring
accidentconditions .
Toachievethissafetyobjective ^"Defenseindepth"conceptis
usuallyemployed.Forexamplefourdifferent sometimessuccessive
andmutuallyreinforcing echelonsofdefensearerequiredto
preventaseriousaccidentaffectingthepublic.
.Afirstechelonofdefenseindepthemphasizes accidentprevention
Itrequiresthattheplantbesoundlyandconservatively designed,
constructed andoperatedinaccordance withstringentqualitylevels
andengineering practices .
Thebasicdesignmustminimizethepossibility ofanticipated
operational occurrences andaccidentconditions .
.Asecondechelonofdefenseisbasedontheassumptionthat
failuresoroperatingerrorswill'occurduringtheservicelife
ofanuclearpowerplant,despitethecaretakentopreventthem.
Accordingly ,specificsystemsarerequiredtopreventorminimize
damagefromsuchfailures.Theaimhereistodetectandintercept
deviationfromnormaloperatingconditionsinordertopreventminor
inciuentsfromescalatingintomajorones.

.Athirdechelonprovidesadditionalsafetysystemstoprotedt
thepublicagainstaccidents.Anvmberofaccidentaev,-ences.
ν ,
areselectedasabasisfortheincorporation oftheseadditional
safetysystemsrequiredtomitigatetheconsequences ofsuch
.events. ' *
.Afourthechelonofdefense,whichisconceptually differentfrom
reactordesign,isemergencypreparedness ;thisrelatestooff-site
aswellason-siteplanning.Emergencypreparedness takesinto•
accountaccidentconditions whichmayleadtoreleaseofradioactive
materialthatgobeyondthose ,oftheeventsconsideredinthethird
echelon.1
Onetechnicalwaytoimplementadefenseindepthconcept ,istheT
preservation ofaseriesofbarrierspreventing theescapeof
radioactive materials. 'i
Thethreeprincipalbarriersarethefollowing ,:
71 •
.Thefirstbarriercomprisesthe,retaining ;abilityofthefuel
matrixandthefuelcladding,Itisessentialtoensurethe
integrityofthisbarcier;thereforereliablecoolingofthe
coreandreactivitycontrolmustbeprovidedto.limitthefuel
andcladdingtemperature duringnormaloperation,-anticipated
operational occurrences suchastransients andinaccident
conditions .Inaddition,reliablemeansmustbeprovidedto
removeresidualheataftershutdowntopreservetheintegrity ^
ofthefuelelements. 11 ;

12.
•Thesecondbarrieristheprimarypressureboundary;withinthis
barriertheheatproduction andtheheatexchangetakeplace.
Thisbarrierpreventstheescapeofanyradioactive materialswhich
arepresentinthecoolingfluid.Lossofintegrityofthisbarrier
leadstoalossofcoolant,whichinturnmightleadtoafailureof
thefuelcladding.Provisionsarethereforenecessarytolimitthe
consequences ofthefailureofthesecondbarrier.
*Thethirdbarrierisconstituted bythecontainment system.
Itsmainfunctionistomitigatetheconsequences ofanescapeof
radioactivematerialsfromtheprimarycircuitandtolimitthe
escapeofthesematerialsintotheenvironment .
Therearefurtheraspectsinconnectionwithgeneralsafetyprinciples.
-V '
^Λ
Theplantmustbeoperatedinsuchamannerthattheprocessand
systemsparametersarekeptwithintheiroperationallimits.Any.
deviationfromoperatingrangesshouldbedetectedandshould
leadtoappropriate actionstokeepprocessandsystemparameters
withintheirsafetylimits.
Itmustbeensure1thatthereliability ofthe:structures ,systems
andcomponentsismaintainedatanadequate ;levelthroughout
plant-lifeinaccordancewiththesafetyfunctionstobeperformed.
Thisisachievedbyproperdesign,construction andoperation,and
byensuringatthedesignstagethatadequatefacilitiesare
availablefortesting,inspection,maintenance andrepair.
Operat,agexperience canprovideanimportantsourceofsafety
guidanceforNPP'sandthereforethelessonsleiarnedfromoperation
andaccidentalconditionsshojlabefedback'intothedesing,
construction an<3operationofnuclearpewerplants.
Anappropriate qualityassuranceprogrammeisrequiredandthe
qualitylevelwustreflectthei»p©rtarv3<2tosafetyofstructures,.
systemsandcomponents .

Ofgreatimportancearealsomanagerial andorganizational aspects,
/
includingqualification andtrainingofpersonnel.
-4 "• ■.•-•
'~r'■: - i-....'Theimpactofthesitecharacteristic ^andtheo^tivitiencarried :
outintheproximityonthej?afet^tofthep'.antshallalsobe
considered.Adequateprot^ctioh'Shdilbeprovr^dagainsteternal
impactsofnaturalorniatyroade''^i,?^n.Suchintactsareearthquakes,
floods,tornadoes,fa'ji;j:piane<;«rashes ,explosions,,firesetc..
■-r \ •'
■ ,/ïî\
Althoughtheimportance iofEmergencyplanningasanultimate
-T.,':•'»4 - -•■
►measurefortheprotection <?£thepublicagainsttheeffectsof
accidentalreleasesisrecognized,itwillnotbetreatedspecifi­
callyinthisdocument.'i1
Theforegoingconsiderations areexpressedinthefollowinggeneral *
safetyprinciples *'-;v»•/ -\v.'j
f-
1.Toimplementthefundamentalsafetyprinciple-thatallpractical
stepsshjallibetakentopreventaccidents^ndtominimizethe
radiological consequences ofanyaccidentshoulditoccur-a
"defenseindepth"strategyshallbeapplied.
Thisstrategyleadstothefollowingrequirements :•
I, ;,-, ;r, ;Design,construction and.operationoftheplantshall
» -· ϊ'; λ» ■..' · ■,
provideadequatesafetymargin?,ixvnormaloperation,preventthe
occurrenceofsystemmalfunction^andminimizethesensitivity
• 'V''<i} ■■'•,oftheplanttofailures,malfunction andmaloperation .
.^' ,.V-V''n-'-'.
■■ -'V- -
. :'_I." .-theplantshallbedesigned^'constructed andoperatedsothat
off-normalconditions/(suchSag'anticipatedoperationaloccurrences )
canbedetectedandminorincidentscanbepreventedfromescalating

14.
-reliable features ,aswell yasoperational and organizational
provisions must beavailable tocope with anycredible internal or
external event orcredible combination ofthem .This requires that
theplant can besafely shut down and kept shut down ,the residual
heat can beremoved and the release ofradioactive materials is
limited . ' >•'
-emergency plans (onsite andoff site )shall beprovided .
2.Asafety evaluation shall beperformed inparticular todemonstrate
that thedesign ,theconstruction and theoperation ofthe plant will
take place according tothedefense indepth strategy .This evaluation
shall bebased ontests ,experience and analysis taking into account
,uncertainties indata and analysis .The safety evaluation shall show
I
which kind ofevents and combination ofthem ,aswell astheir conse­
quences ,are taken into account .
3.Structures ,systems and components important tosafety shall be
designed ,fabricated ,erected ,inspected andtested toaquality level
commensurate with the importance ofthe safety functions tobe
performed .Where codes and standards are used ,they shall be
identified and evaluated todetermine their adequacy and shall
besupplemented ormodified ifnecessary *.
Aquality assurance programme shall beestablished and implemented
in or:-'M:toprovide adequate assurance that these structures ,
systen :: >ndcomponents will satisfactorily perform their safety
functic is .vhen required throughout their anticipated operational
life in heplant . 1
More ingleral tir'-e shall beacot .r».ehensive quality assurance
programme thedesign ,construction ,commissioning ,operation
and decommissioning covering all act.iv:l :ies which may have an
influence onthe «a:Tety oftheNPP .

.Thereliability ofabar;itorofasafetysystemshallbe
commensurate withthesai'yfunctionithastoperform.
Equipmentoutages,singlefailures,commonmodefailures,and
consequential failures (e,g.fromequipmentfailures)havetobe
takenintoaccount.Suitablemeasuresshallbetakentominimize
theprobability ofoccurrence ofco®onmodofailures.Other
systems,structuresorcomponentsthatmayinfluencethssafety
performanceofthesebarriers,safetysystemsortheplantasa
wholealsoshallbeconsidered . ;
<'I''
Therequirements forsafetysystemsupportfeaturesshallbe
■i I
consistentwiththoseforth^safetysystemssupplied.
AllitemsimportanttosafetyshajLlbetestableandmaintainable
commensurate withthesafetyfunctiontobeperformed.Ifstructures
systemsorcomponentsimportarttto'safetycannotbetestedtothe
extentdesirable,adequatesafetyprecautionsshallbetakento
compensateforpossibleundiscovered failures.
Theeffectsofradiation andotherenvironmental conditionsshall
beconsidered inthiscontext. ;
ry
Inadditiontotheprotectionagainstinternalevents,includingfor
instancelossofcoolant,fireandexplosion,turbineexplosionetc.
protectionagainstexternalevents,eithernatural(earthquakes,
tornadoes,floodsetc.)orman-made (aircraftcrashes,chemical
worksaccidents,miningoperationsetc.),hastobetakeninto
account.Aquantitative probabilistic approachoftheseexternal
eventsandtheirconsequences maybeconsidered#
i
Interactionbetweentheplantandtheenvironmentshallbetaken
intoaccount.Inthiscontext,amongstotherS/off–siteservices,
uponwhichthesafetyoftheplantandprotectionoftheplant
personnelandthepublicmaydepend,shallbeconsidered,for
exampleultimateheatsink^electricitysupply^andfirefighting
services.

16.
8.Structures .--ysternsandcomponents importanttosafetyshallnot
besharedbetweennuclearpowerunitsononesite,unlessitcan
bedemonstrated thatanaccidentcondition inoneunitwillnot
affecttheorderlyshutdown,cooldownandresidualheatremoval
oftheotherunitonthesite,takingintoaccountsituations suchas
thelossofoff-siteelectrical power.
9.Intheinterestofsafetyappropriate ergonomicprinciples shall
beappliedintheworkingareasandtheworkingenvironment ofthe
sitepersonnelwithdueregardtotheactionstobetakenbythese
personnelduringnormaloperation and.duringaccidentsituations .
Inadditionthepossibility oferrorsbysitepersonnelshouldbe
minimized byproperdesignandadministrative measures.
10.Accesstothesafetyandsupportsystemsshallbeappropriately
limited,bearinginmindtheneedtoprevent .unauthorized access
andtoguardagainstunintentional orintentional damage.Themethods
employedshallincludeappropriate combinations ofphysicalprotec­
tionandadministrative measures.
11.Thepersonneliriustbesufficiently qualified andtrainedtoperform
therequiredtasks. - >■;

L'ARTIII
Subjectsforsafetyrequirements
1.Introduction
WhilePartIIpresentsgeneralsafetyprinciples ,whichhaveanoverall
importancefortheNPP,PartIIIlistssystematically themainkeywords
forsafetyrequirements someofwhichmightbedevelopedatalater
stage.
Itisrecognizedthatsomerequirements covermorethanoneofthephasesof:
-siting,
-design,
-construction , * ;:
-commissioning ,
-operation,
-decommissioning ;
theserequirements haveadifferentcharacterfromithoseassociated with
thephasesgivenabove.Theyrelatetotheareasofs
-safetyevaluations ,
-qualityassurance,
-radiological protection ,includingwastetreatment,
-ergonomics ,
-emergencyplanning.
Forthespecificphasesofdesign,construction ,commissioning ,operation,
decommissioning ,generalrequirements shouldbedevelopedrelatedtoevery
particular phase,followedbyspecificrequirements relatedtothespecific
*
subjectsofthatphase.
Afigureisattachedwhichshowsinadiagrammatic formanoutlineofthe
proposedschemeforsafetyrequirements . .
A

18.
Section2n.fthisFartIIIgivesadraftlistofthesubjectsof
genaralar:dspecificrequirements forthephases,andSection3
liststhemaintopicstodevelopsafetyrequirements forthe
areas.
2.Safetyrequirements forthephases.
* '
2.1.SITING
Generalrequirements ;
-generalcriteriaforsitescreeninaandsiteselection
ii<
-criteriafortakingintoaccountexternalevents
-criteriafordefiningpotentialeffectsoftheNPPon
theregion
-populationconsiderations
Specific_requirernents for_specif!icsubjects
-floods
-geologyansseismology
-tornadoes
-aircraftcrashes
-chemicalexplosions andeffectsofdangerousgases
-dispersion ofradioactive materialsm
-site-related radioecology aspects
-populationdistribution
-furthersite-related parameters .
■-,«
*AccordingtoPartI,atthissitingaspectsarearatter
ofexchangeofinformations only.■

jiiiJ:
19.
.2DESIGN
Generalrequirements
-safetyclassifications
-reliability aspects(probabilistic ,deterministic ;sing.irfailure
criterion,diversity,physicalseparation ,fail-safebehavio.ur )
-multiplantsite
\•
-decommissioning provisions .
■4- :•
Specificre<juirements_for specificsubjects
Structures,components andsystems
-designagainstexternalevents(naturalandman-made)
-effectsassociatedwithequipmentfailures (e.g.missiles,
pipewhip)
-protectionagainstfireandexplosions
-buildings (incl«containment )
,'. ' J
Reactorcore
-reactordesign(incl.,inherentsafety)
-fuelelements
-reactorcorecontrol 1. /
-reactorinternals
Reactorcoolantsystem
Λ
-reactorcoolantsystemoveralldesign
-pressureboundary
-residualheatremoval
-emergencycorecooling
-auxiliaries forreactorcoolantsystem(e.j.reactor <"<~o
up)~
Powerconversionsystem
-steamgenerators
-turbine

20.
Instrument ?4-ion-indccn;:rol
-^nsùrument^tion ove:-alldesign
-control-room andsupplementary control-points
-radiation ;aonircaii.qandcontrolofreleaseofradioactive material
-incidentinstrumentation
-safetyrelatedinstrumentation
ΜΓ*
Reactorprotection system
* ?
-separation fromcontrolsystem
Electricpowersupply
-on-sitepower
-off-sitepower
-emergencypower 1:
Containment system ,
-overalldesign(e.g.leakage,testing,isolation )
-auxiliaries (e.g.heatremovalsystem;atmospherecleanupsystem,
containment internals )
Auxiliarysystems
-fuelhandlingandstorage
-ventilation systems
-fir^protectiont^stems
-furtherauxiliarysystems

21
2.3COMMISSIONING ANDOPERATION '
Generalrequirements _
-operationsurveillance /;
-managementorganization ,
-operationallimitsandconditions .
-recruitment ,trainingandauthorization ofpersonnel
Specificrequirements forspecificsubjects
Commissioning
-programme „
-testprocedures
Operation
-procedures (poweroperation,refuelling,shuttingdown,
plantmodifications ,etc.)
-Ainstructions (operatingmanual;recordsandreports,including
incidentreportmg,etc.)
Maintenance ,testing,examination andinspection
-programme ■..
-procedures.

22.
2.4 DECOMMI SSIOKING
Atthis stage ,norequirement isgiven for this phase .
3.Safety requirements for the areas
3.1SAFETY EVALUATIONS
Requirements
.Objectives
.Documentation (safety reports and supporting documents )
.Procedures
.Stages and topics
M
.Methodology
-deterministic (single failure criteria ,postulated
initiating events
-probabilistic (risk concept ,fault tree ,reliability .
3.2 QUALITY ASSURANCE
Requiregents
-Programmes
-Organization
-Control (document ,design ,procurement ,material ,process )
-Inspection
•Non-conformance
-Corrective actions
-Records
-Audits

23.
3.3RADIOLOGICAL PROTECTION ,INCLUDING FUELHANDLING AND
WASTETREATMENT
.Requirements
-Radiological protectionaspectrelatedtositing
-Radiological protectioninthedesignstage
\'
-" ".duringoperation
-Fuelhandlingandmanagement V-;
-Wastetreatment , >.
'- ,y-.i.'•«;..'À'■\>•!
•J•»''f"'.•«•
3.4ERGONOMICS ;5'}VT\^•i-,y>A
s-iI•'
■1:uRequirements :t.
-Work-Environment (e.g.climate,lighting,noiseandvibra­
tions) f,
,4-Work-Area (e.g.designandarrangementofactuatorsand
indicators ) ' |
-Plantregulations andorganization ofwork.
3.5EMERGENCY PLANNING V ;\
Requirements _
-On-siteplanning
-Off-siteplanning
-Coordination ofon-siteandoff-siteresponsabilitiet

Fundamental Safety Principles Part I
-I-
General Safety Principles Part II
t
Safety Requirements
(phases ^»Part III
(areas )
Sitino Design Commis -Operation iDecommis-i Ssfety Quality Radici^Ergono -Emergency
sioning isioning i evalua-H assu - logical mics Planning
1i 1 I 1I 1 tions rance protec -
J tion
• ( i ^ (.General Requirements I I j I I\
' ' f(sogeneral thatthey - __ jJcanbeapplied to /
allsubjects ) - - _ J
-Reactor J Vdesign I ----- /Requirements
-Struc -7- -Personnel / I
-T--ture s, qualification [ |
: systems I 1
-Core -Start-up \.Specific requirements ^
cooling /(specific tosubjects )
- -Records and \
reports \
5: /
' S;
/; » ■:
6 ■ . . > < •M Flnurp -Srhpmp fnr cafptv rpnniromont-c r SFigure -Scheme forsafety requirements { !,– \
\ \ k

25.
APPENDIX
DEFINITIONS
Τ-·
Thefollowingdefinitions aretakenfromtheCodesofPracticeof
theIAEASafetySene-50. ■■i
• i.1 ■'
;■p''>''!•"VAccidentconditions 7
Substantialdeviations jfypni'OperationalStateswhichareexpectedto
beinfrequent,andwhich,couldjl'e^dtoreleaseofunacceptable quantities
''.■"!"!<i. .' .ofradioactive materialsifvtlie'relevantengineeredsafetyfeaturesdid
'M"V
notfunctionasperdesignintent.
i , -,
Anticipated Operational Occurrences
AlloperationalprocessesdeviatingfromNormalOperationwhich
areexpectedtooccuronceorseveraltimesduringtheoperatinglifeof
theplantandwhich,inviewofappropriate designprovisions ,do
notcauseanysignificant damagetoItemsImportanttoSafetynor
leadtoAccidentConditions (seeOperational States)* ^
»
Λ '·.-· ■ItemsImportanttoSafety
Theitemswhichcomprise:
(1)thosestructures,systems,andcomponents whosemalfunction
orfailurecouldleadtoundueradiationexposureoftheSite
*'Personnelormembersofthepublic; ,
(2)thosestructures,systemsandcomponent ?whichprevent
Anticipated Operational Occurrences fromleadingtoAccident
Conditions ; in
(3)thosefeatureswhichareprovidedtQmitigatetheconsequences
ofmalfunctionorfailureofstructures,systemsorcomponents.
Thisincludessuccessivebarrierssetupagainsttherolea^eof.adioactivity
fromnuclearfacilities .

n,
>1
NormalOperation
OperationofaNuclearPowerPlantwithinspecifiedOperational
LimitsandConditionsincludingshut-down,poweroperation,
shuttingdown,startingup,maintenance ,testingandrefuelling
(seeOperational States)•
Operation * 1
Allactivities performedto"achieve,inasafemanner,the
purposeforwhichthepl^p^'was;const>ructed,includingmaintenance ,
refuelling ,in-service inspection andotherassociatedactivities .
Operational LimitsandConditions ■
Asetofruleswhichsetforthparameterlimits,thefunctional
capability andtheperformance levelsofequipmentandpersonnel
approvedbytheRegulatory BodyforsafeoperationoftheNuclear
PowerPlant.
Operational States
ThestatesdefinedunderNormalOperationandAnticipated
Operational Occurrences (seeNormalOperationandAnticipated
Operational occurrences ).
Prescribed Limits**
Limitsestablished oracceptedbytheRegulatory Body.
*ThetermsSiting,Construction ,Commissioning ,Operationand
Decopmmissioning areusedtodelineatethefivemajorstagesofthe
licensingprocess.Severalofthestagesmaycoexistforexample,
Construction andCommissioning ,orCommissioning andOperation .
**Theterm"authorised limits"issometimes usedforthisterm.

27.
Protection System
Asystemwhichencompassesallelectrical .andmechanical
devicesandcircuity,fromsensorstoactuationdeviceinput
terminals,involvedingenerating thosesignalsassociated with
theprotectivefunction. '
Protective System
Asafetysystemdesignedandinstalledtoactautomatically
toensurethatoneormoreSafetyLimitsarenotviolated.
QualityAssurance -
Plannedandsystematicactionsnecessarytoprovideadequate
confidencethatanitemorfacilitywillperformsatisfactorily
inservice.
Reliability *
Theprobabilitythatadevice,systemorfacilitywillperform
itsintendedfunctionsatisfactorily foraspecifiedtimeunder
statedoperatingconditions.
ResidualHeat .v': v
The-sum"of.theheatoriginating fromradioactive decayand
shut-downfissionandtheheatstoredinreactor-related structures
andinheattransportmedia.
SafetyLimits -^ .
LimitsuponprocessvariableswithinwhichtheOperation ,ofthe
NuclearPowerPlanthasbeenshowntobesafe*

28.
SafetySystems
ν
SystemsimportanttoSafety,providedtoassure,inanycondition,
thesafeshut-downofthereactorandtheheatremovalfromthe
core,and/ortolimittheconsequences ofAnticipated Operational
Occurrences andAccidentConditions (seeAnticipated Operational
Occurrences andAccidentConditions ).
SingleFailure
Arandomfailurewhichresultsinthelossofcapabilityofa
componenttoperformitsintendedsafetyfunctions.Consequential
failui.esresultingfromaSinglerandomoccurrenceareconsidered .
tobepartofthesinglefailure. -
Site
Thaareacontainingtheplant,definedbyaboundaryandunder
effectivecontrolofthePlantManagement
1;
SitePersonnel
AllpersonsworkingontheSite,eitherpermanently ortemporarily