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首页文档碳中和资料研究报告日本福岛核电站处理水排放综合报告（英文版）-国际原子能权威发布

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IAEA COMPREHENSIVE
REPORT ON THE
SAFETY REVIEW
OF THE ALPS-TREATED
WATER AT THE
FUKUSHIMA DAIICHI
NUCLEAR POWER STATION
© IAEA, 2023
This is a report by the IAEA of the IAEA Review of Safety Related Aspects of Handling ALPS-Treated Water
at TEPCO’s Fukushima Daiichi Nuclear Power Station. The views expressed herein do not necessarily
reflect those of IAEA Member States. Although great care has been taken to maintain the accuracy of
information contained in this report, neither the IAEA nor its Member States assume any responsibility for
consequences which may arise from its use. The use of particular designations of countries or territories
does not imply any judgement by the IAEA, as to the legal status of such countries or territories, of their
authorities and institutions or of the delimitation of their boundaries. The mention of names of specific
companies or products (whether or not indicated as registered) does not imply any intention to infringe
proprietary rights, nor should it be construed as an endorsement or recommendation on the part of the
IAEA. The IAEA assumes no responsibility for the accuracy or continuing existence of URLs for external
or third party internet web sites referred to in this report and does not guarantee that any content on such
web sites is, or will remain, accurate or appropriate.
IAEA COMPREHENSIVE
REPORT ON THE
SAFETY REVIEW
OF THE ALPS-TREATED
WATER AT THE
FUKUSHIMA DAIICHI
NUCLEAR POWER STATION
/140
文本预览下载提示常见问题
IAEACOMPREHENSIVEREPORTONTHESAFETYREVIEWOFTHEALPS-TREATEDWATERATTHEFUKUSHIMADAIICHINUCLEARPOWERSTATION©IAEA,2023ThisisareportbytheIAEAoftheIAEAReviewofSafetyRelatedAspectsofHandlingALPS-TreatedWateratTEPCO’sFukushimaDaiichiNuclearPowerStation.TheviewsexpressedhereindonotnecessarilyreflectthoseofIAEAMemberStates.Althoughgreatcarehasbeentakentomaintaintheaccuracyofinformationcontainedinthisreport,neithertheIAEAnoritsMemberStatesassumeanyresponsibilityforconsequenceswhichmayarisefromitsuse.TheuseofparticulardesignationsofcountriesorterritoriesdoesnotimplyanyjudgementbytheIAEA,astothelegalstatusofsuchcountriesorterritories,oftheirauthoritiesandinstitutionsorofthedelimitationoftheirboundaries.Thementionofnamesofspecificcompaniesorproducts(whetherornotindicatedasregistered)doesnotimplyanyintentiontoinfringeproprietaryrights,norshoulditbeconstruedasanendorsementorrecommendationonthepartoftheIAEA.TheIAEAassumesnoresponsibilityfortheaccuracyorcontinuingexistenceofURLsforexternalorthirdpartyinternetwebsitesreferredtointhisreportanddoesnotguaranteethatanycontentonsuchwebsitesis,orwillremain,accurateorappropriate.IAEACOMPREHENSIVEREPORTONTHESAFETYREVIEWOFTHEALPS-TREATEDWATERATTHEFUKUSHIMADAIICHINUCLEARPOWERSTATIONIOutlineoftheIAEAComprehensiveReportDirectorGeneral’sForewordIIIExecutiveSummaryIVPART1INTRODUCTION11.1.Background11.2.TheComprehensiveReport91.3.TheIAEAinternationalsafetystandards10PART2ASSESSMENTOFCONSISTENCYWITHTHEFUNDAMENTALSAFETYPRINCIPLES132.1.ResponsibilityforSafety142.2.RoleoftheGovernment152.3.LeadershipandManagementforSafety172.4.Justification182.5.OptimizationofProtection202.6.LimitationofRiskstoIndividuals232.7.ProtectionofPresentandFutureGenerationsandtheirEnvironment252.8.PreventionofAccidents282.9.EmergencyPreparednessandResponse292.10.ProtectiveActionstoReduceExistingRadiationRisks31PART3ASSESSMENTOFCONSISTENCYWITHSAFETYREQUIREMENTS333.1.RegulatoryControlandAuthorization333.2.SafetyRelatedAspectsofSystemsandProcessesforControllingDischarges433.3.CharacterizationoftheSource543.4.RadiologicalEnvironmentalImpactAssessment593.5.SourceandEnvironmentalMonitoring843.6.InvolvementofInterestedParties943.7.OccupationalRadiationProtection98PART4MONITORING,ANALYSIS,ANDCORROBORATION1034.1.OverviewofCorroborationActivities103PART5FUTUREACTIVITIES1115.1.ReviewMissions1125.2.IAEA’sIndependentSampling,DataCorroboration,andAnalysis1145.3.RealTimeMonitoring1155.4.IAEAContinuousPresenceattheFDNPS116REFERENCES117LISTOFCONTRIBUTORS119ANNEX1:SummaryofIAEAReviewMissionsandPublishedTechnicalReports121ANNEX2:SummaryofrelevantinternationalsafetystandardsusedintheIAEAsafetyreview122ANNEX3:ListofupdatesandamendmentstoTEPCO’sImplementationPlanandNRARegulatoryReviewMilestones123ANNEX4:JapanlegalandregulatoryprovisionsappliedtotheFDNPS125ANNEX5:TritiumintheEnvironment129OutlineoftheIAEAComprehensiveReportFOREWORDbytheDirectorGeneral1ExecutiveSummary2Part1:IntroductionandBackground51.Background52.TheComprehensiveReportx3.IAEAInternationalSafetyStandardsxPart2:AssessmentofAdherencetotheFundamentalSafetyPrinciplesx1.Principle1–Responsibilityforsafetyx2.Principle2–Roleofgovernmentx3.Principle3–Leadershipandmanagementforsafetyx4.Principle4–Justificationoffacilitiesandactivitiesx5.Principle5–Optimizationofprotectionx6.Principle6–Limitationofriskstoindividualsx7.Principle7–Protectionofpresentandfuturegenerationsx8.Principle8–Preventionofaccidentsx9.Principle9–Emergencypreparednessandresponsex10.Principle10–ProtectionactionstoreduceexistingorunregulatedradiationrisksxPart3:AssessmentofAdherencetotheSafetyRequirements1.Regulatorycontrolandauthorizationofdischarges2.Safetyrelatedaspectsofsystemsandprocessesforcontrollingdischarges3.Characterizationofthedischargeandsourceterm4.Radiologicalenvironmentalimpactassessment5.Sourceandenvironmentalmonitoringprogrammes6.Involvementofinterestedparties7.OccupationalradiationprotectionPart4:Monitoring,Analysis,andCorroboration1.CorroborationofSourceMonitoring2.CorroborationofEnvironmentalMonitoring3.CorroborationofOccupationalRadiationProtectionPart5:FutureActivities1.ReviewMissions2.IAEA’sIndependentSampling,DataCorroboration,andAnalysis3.RealTimeMonitoringReferencesListofcontributorsAnnexes1.ApplicableIAEAinternationalsafetystandards2.Timelineofmissionsandreports3.ImplementationPlanRevisionsandNRAMilestones4.SummaryofApplicableJapaneseRegulationsandLaws5.TritiumintheEnvironmentIIIDirectorGeneral’sForewordTheaccidentatFukushimaDaichiNuclearPowerStationinMarch2011andthesubsequentoperationsattheplanthaveresultedintheaccumulationoflargeamountsofwaterstoredonthesite.InApril2021,theGovernmentofJapanpublisheditspolicyonhowitwouldmanagethiswater.Itdecidedtodischargeitgraduallyintotheseaafterspecifictreatment.Shortlyafterthedecisionwasmade,theGovernmentofJapanrequestedthattheIAEAundertakeanindependentsafetyreviewofJapan’simplementationofitspolicyagainsttheinternationalsafetystandards.IagreedwithJapanthattheIAEAwouldreviewtheimplementationoftheGovernment’splanscomprehensivelybefore,during,andafteranydischargeoftheALPS-treatedwater.Thatyear,IestablishedanIAEATaskForce.ItismadeupoftopspecialistsfromwithintheIAEA’sSecretariatadvisedbyinternationallyrecognizedoutsideexpertsfromacrosstheglobe,includingwithintheregion.Bythenatureofitsstatutorymandateandglobalreach,theIAEAisabletousetheinternationallyagreednuclearsafetystandardsasanobjectiveblueprintforassessingthesafetyoftheplanneddischarges.Theseinternationalstandardsareconstantlyupdated,takingintoaccountadvancesinscienceandtechnologyandlearningsfromresearchandexperience.Theyserveastheindispensableglobalreferenceforprotectingpeopleandtheenvironment,therebycontributinggreatlytoaharmonizedandhighlevelofnuclearsafetyworldwide.ThiscomprehensivereportmakesthescienceofthetreatedwaterreleaseclearfortheinternationalcommunityandIbelieveanswersthetechnicalquestionsrelatedtosafetythathavebeenraised.Basedonitscomprehensiveassessment,theIAEAhasconcludedthattheapproachandactivitiestothedischargeofALPStreatedwatertakenbyJapanareconsistentwithrelevantinternationalsafetystandards.Furthermore,theIAEAnotesthecontrolled,gradualdischargesofthetreatedwatertothesea,ascurrentlyplannedandassessedbyTEPCO,wouldhaveanegligibleradiologicalimpactonpeopleandtheenvironment.ThesefindingsandthiscomprehensivereportrepresentasignificantmilestoneintheIAEA’sreview.Evenso,ourtaskisonlyjustbeginning.TheIAEAwillcontinueitsimpartial,independentandobjectivesafetyreviewduringthedischargephase,includingbyhavingacontinuouson-sitepresenceandbyprovidingliveonlinemonitoringonourwebsite.Thiswillensuretherelevantinternationalsafetystandardscontinuetobeappliedthroughoutthedecades-longprocesslaidoutbytheGovernmentofJapanandTEPCO.Bydoingso,theIAEAwillcontinuetoprovidetransparencytotheinternationalcommunitymakingitpossibleforallstakeholderstorelyonverifiedfactandsciencetoinformtheirunderstandingofthismatterthroughouttheprocess.Finally,IwouldliketoemphasisethatthereleaseofthetreatedwaterstoredatFukushimaDaiichiPowerStationisanationaldecisionbytheGovernmentofJapanandthatthisreportisneitherarecommendationnoranendorsementofthatpolicy.However,IhopethatallwhohaveaninterestinthisdecisionwillwelcometheIAEA’sindependentandtransparentreview,andIgiveanassurance,asIsaidrightatthestartofthisprocess,thattheIAEAwillbetherebefore,duringandafterthedischargeofALPStreatedwater.RafaelMarianoGrossiDirectorGeneral,IAEAIVExecutiveSummaryInApril2021,theGovernmentofJapanreleaseditsBasicPolicyonHandlingofALPSTreatedWaterattheTokyoElectricPowerCompanyHoldings’(TEPCO)FukushimaDaiichiNuclearPowerStation(BasicPolicy).ThispolicyresultedfromaprogrammeofreviewbytherelevantJapanesegovernmentministries,andTEPCO,abouthowtomanagetheaccumulatingALPStreatedwaterstoredonsiteattheFukushimaDaiichiNuclearPowerStation(FDNPS).TheBasicPolicydescribes,amongothertopics,themethodselectedbytheGovernmentofJapanforthehandlingoftheAdvancedLiquidProcessingSystem(ALPS)treatedwaterwhichwastodischargethetreatedwaterintothesea.Followingtheannouncementofthispolicy,theGovernmentofJapanrequestedthattheIAEAconductadetailreviewofthesafetyrelatedaspectsofhandlingALPStreatedwaterstoredatFDNPS,applyingtherelevantinternationalsafetystandards.TheIAEADirectorGeneralacceptedthisrequestandnotedtheIAEA’scommitmenttobeinginvolvedbefore,during,andaftertheALPStreatedwaterdischarges.TheIAEAisconductingthisreviewincompliancewithitsrelevantIAEAstatutoryfunctions,inparticular,thatestablishedinArticle3.A.6oftheIAEAStatutewhichdeclaresthattheAgencyisauthorized:“Toestablishoradopt,inconsultationand,whereappropriate,incollaborationwiththecompetentor-gansoftheUnitedNationsandwiththespecializedagenciesconcerned,standardsofsafetyforprotectionofhealthandminimizationofdangertolifeandproperty(includingsuchstandardsforlabourcondi-tions),…andtoprovidefortheapplicationofthesestandards,…attherequestofaState,toanyofthatState’sactivitiesinthefieldofatomicenergy.”InJuly2021,theIAEAandtheGovernmentofJapansignedtheTermsofReferenceforIAEAAssistancetoJapanonReviewofSafetyAspectsofALPSTreatedWateratTEPCO’sFDNPS.TheIAEAactivitiesinthisregardconsistofatechnicalreviewtoassesswhethertheactionsofTEPCOandtheGovernmentofJapantodischargetheALPStreatedwateroverthecomingdecadesareconsistentwithinternationalsafetystandards.TheIAEAisalsoundertakingallnecessaryactivitiesforthecorroborationofthesourceandenvironmentalmonitoringprogrammesofTEPCOandtheGovernmentofJapanbefore,duringandafterthedischarges.TheIAEA’sreviewisorganizedintothefollowingthreemajorcomponentstoensureallkeysafetyelementsareadequatelyaddressed:1)AssessmentofProtectionandSafety,2)RegulatoryActivitiesandProcesses,and3)IndependentSampling,DataCorroboration,andAnalysis.ToimplementtheIAEA’sreviewinatransparentandinclusivemanner,theIAEADirectorGeneralestab-lishedaTaskForce.TheTaskForceoperatesundertheauthorityoftheIAEAandischairedbyaseniorIAEAofficial.TheTaskForceincludesexpertsfromtheIAEASecretariatalongsideinternationallyrec-ognizedindependentexpertswithextensiveexperiencefromawiderangeoftechnicalspecialtiesfromArgentina,Australia,Canada,China,France,theMarshallIslands,theRepublicofKorea,theRussianFederation,theUnitedKingdom,theUnitedStatesandVietNam.TheseindependentexpertsprovideadviceandserveontheTaskForceintheirindividualprofessionalcapacitytohelpensuretheIAEA’sreviewiscomprehensive,benefitsfromthebestinternationalexpertiseandincludesadiverserangeoftechnicalviewpoints.SinceSeptember2021whentheIAEATaskForcehelditsfirstmeeting,therehavebeenfivereviewmis-sions,sixtechnicalreports,andnumerousTaskForcemeetings.AsummaryoftheseactivitiesandkeymilestonesareincludedinAnnex1.ThroughoutthisprocesstheTaskForcereceivedinformationfromtheGovernmentofJapanandTEPCOwhichhelpedtheexpertstobetterunderstandthetechnicalandregulatoryaspectsoftheplanneddischargesofALPStreatedwater.ThetechnicalreportsofthemissionsincludesummariesoftheIAEA’sreviewandshowtheprogressmadebyTEPCOandtheGovernmentofJapan.Overthepasttwoyears,theTaskForceandtheGovernmentofJapanhaveidentifiedandbuiltonVtheobservationsfromthesepreviousmissionsandtheIAEAisnowinapositiontodrawcomprehensiveconclusionsaboutthesafetyofthedischarge.Additionally,thisreviewisoccurringconcurrentlywithJa-pan’sNuclearRegulationAuthority’s(NRA)domesticregulatoryreviewandapproval.Therefore,thein-sightsfromtheIAEA’sreviewwereconsideredinthedomesticprocessinatimelyandbeneficialmanner.Thiscomprehensivereportincludesexplanationsandinsightsoverabroadrangeoftopicsthatareimport-anttounderstandingtheoverallsafety-relatedaspectsofthisprocess;thisrepresentsthe“before”stageoftheIAEA’sreviewasnotedbytheIAEADirectorGeneral.ThepurposeofthiscomprehensivereportistopresenttheIAEA’sfinalconclusionsandfindingsofthetechnicalreviewtoassesswhethertheplannedoperationtodischargetheALPStreatedwaterintothePacificOceanoverthecomingdecadesisconsis-tentwithrelevantinternationalsafetystandards.Thereviewsofindividualtopicsincludedinthiscompre-hensivereportarebasedonhundredsofpagesoftechnicalandregulatorydocumentation,condensedandsummarizedtohelpmaketheconclusionsfromtheIAEA’sreviewmoreaccessibleandunderstandableforthegeneralpublic.AsummaryofrelevantinternationalsafetystandardsisincludedinAnnex2.InordertofullyassesswhethertheALPStreatedwaterdischargeisconductedinamannerthatisconsis-tentwithrelevantinternationalsafetystandards,theTaskForceconsideredtheFundamentalPrinciplesforSafety,theSafetyRequirements,andthesupportingSafetyGuides,publishedbytheIAEA.Thesestan-dardsarestandardsofsafetyfortheprotectionofhealthandminimizationofdangertolifeandproperty.IncompliancewiththeIAEA’sstatutoryfunctions,theseinternationalsafetystandardsaredevelopedandco-sponsoredinconsultationwithand,whereappropriate,incollaborationwiththecompetentorgansoftheUnitedNationsandwithspecializedagencies.Theyserveasaglobalreferenceforprotectingpeopleandtheenvironmentandcontributetoaharmonizedhighlevelofsafetyworldwide.Thisreportincludesanassessmentoftheapplicationofthefundamentalsafetyprinciples,therelevantsafetyrequirements,andsupportingsafetyguides.Itisimportanttonotethatintheapplicationoftheinternationalsafetystandards,theirprinciplesandtechnicalconsiderations,mustbeadaptedtonationalcircumstances.Basedonitscomprehensiveassessment,theIAEAhasconcludedthattheapproachtothedischargeofALPStreatedwaterintothesea,andtheassociatedactivitiesbyTEPCO,NRA,andtheGovernmentofJapan,areconsistentwithrelevantinternationalsafetystandards.TheIAEArecognizesthatthedischargeoftheALPStreatedwaterhasraisedsocietal,politicalandenvi-ronmentalconcerns,associatedwiththeradiologicalaspects.However,theIAEAhasconcluded,basedonitscomprehensiveassessment,thatthedischargeoftheALPStreatedwater,ascurrentlyplannedbyTEPCO,willhaveanegligibleradiologicalimpactonpeopleandtheenvironment.Notwithstandingtheaboveconclusions,theIAEAnotesthatonceanydischargesbegin,manyofthetechnicaltopicsreviewedandassessedbytheTaskForcewillneedtoberevisitedbytheIAEAatvarioustimestoassesstheconsistencyofactivitiesduringtheoperationoftheALPStreatedwaterdischargeswithrelevantinternationalsafetystandards.OnMay2023,theIAEApublishedareportdetailingtheresultsofthefirstinterlaboratorycomparisonconductedforthedeterminationofradionuclidesinsamplesofALPStreatedwater.Thesefindingspro-videconfidenceinTEPCO’scapabilityforundertakingaccurateandprecisemeasurementsrelatedtothedischargeofALPStreatedwater.Furthermore,basedontheobservationsoftheIAEA,TEPCOhasdemonstratedthatithasasustainableandrobustanalyticalsysteminplacetosupporttheongoingtechni-calneedsatFDNPSduringthedischargeofALPStreatedwater.TheIAEAiscommittedtoengagingwithJapanonthedischargeofALPStreatedwaternotonlybefore,butalsoduring,andafterthetreatedwaterdischargesoccur.ThefindingsaboverelatetoactivitiestheTaskVIForceperformedbeforethewaterdischargesstart.However,theworkoftheIAEAandtheTaskForcewillcontinueformanyyears.TheIAEAwillmaintainanonsitepresenceatFDNPSthroughoutitsreviewandwillpublishavailabledataforusebytheglobalcommunity,includingtheprovisionofreal-timeandnearreal-timemonitoringdatafromFDNPS.Additionalreviewandmonitoringactivitiesareenvisagedthatwillcontinueandwhichwillprovideadditionaltransparencyandreassurancetotheinternationalcommunitybycontinuouslyprovidingfortheapplicationoftherelevantinternationalsafetystandards.1INTRODUCTION1.1.BackgroundTheAccidentattheFukushimaDaiichiNuclearPowerStationTheGreatEastJapanEarthquakeoccurredon11March2011withamagnitudeof9.0andsubsequentlycausingatsunamiwhichstruckawideareaofcoastalJapan,includingthenorth-easterncoast,whereseveralwavesreachedheightsofmorethantenmetres.TheearthquakeandtsunamicausedgreatlossoflifeandwidespreaddevastationinJapan.Around20,000peoplewerekilled,andover6,000wereinjured.Considerabledamagewascausedtobuildingsandinfrastructure,particularlyalongJapan’snorth-easterncoast.AttheFukushimaDaiichiNuclearPowerStation(FDNPS),operatedbytheTokyoElectricPowerCompany(TEPCO),theearthquakecauseddamagetotheelectricpowersupplylinestothesite,andthetsunamicausedsubstantialdestructionoftheoperationalandsafetyinfrastructureonthesite.Thecombinedeffectledtothelossofon-siteandoff-siteelectricalpower.Thisresultedinthelossofthecoolingfunctionatthethreeoperatingreactorunitsaswellasatthespentfuelpools.Fourothernuclearpowerplantsalongthecoastwerealsoaffectedtodifferingdegreesbytheearthquakeandtsunami.However,alloperatingreactorunitsattheseplantsweresafelyshutdown.DespitetheeffortsoftheoperatorsattheFDNPStomaintaincontrol,thereactorcoresinUnits1,2and3overheated,thenuclearfuelmelted,andthethreecontainmentvesselswerebreached.Hydrogenwasreleasedfromthereactorpressurevessels,leadingtoexplosionsinsidethereactorbuildingsinUnits1,3and4thatdamagedstructuresandequipmentandinjuredpersonnel.Radionuclideswerereleasedfromtheplanttotheatmosphereandweredepositedonlandandontheocean.Therewerealsodirectreleasesintothesea.Peoplewithinaradiusof20kmofthesiteandinotherdesignatedareaswereevacuated,andthosewithinaradiusof20–30kmwereinstructedtoshelterbeforelaterbeingadvisedtovoluntarilyevacuate.Restrictionswereplacedonthedistributionandconsumptionoffoodandtheconsumptionofdrinkingwater.FollowingstabilizationoftheconditionsofthereactorsattheFDNPS,theworkondecommissioningbeganandhasbeenunderwaysince.Effortstowardstherecoveryoftheareasaffectedbytheaccident,includingremediationandtherevitalizationofcommunitiesandinfrastructure,beganin2011.PART12ManagementofContaminatedWateratFDNPSBeforetheaccident,groundwaterflowingfromthemountainsidetotherearoftheFDNPSwaspumpedatarateofapproximately850m3perdayfromsub-drainslocatedaroundthebuildingsofUnits1–4tocontrolthegroundwaterlevelandavoidlocalizedflooding.Becauseoftheaccident,thesub-drainsandpumpsthatpreventedgroundwaterfromenteringthebuildingsceasedoperation.Sincethereactorvesselsarenolongerintact,andthenuclearmaterialfromthecoresarenolongercontainedinthereactorvessels,thegroundwatercomingintothereactorbuildingscanmixwithradioactivedebrisresultingincontaminatedwater.Additionally,thegroundwaterthatentersthereactorbuildingsisalsousedtocoolthefueldebrisinordertokeepthereactorsinastablecondition.Finally,duetothedegradedconditionsofthereactorbuildings,rainwaterisabletoenterthebuildingandmixwiththefueldebrisaswell.Thecontaminatedwater,whichishighlyradioactive,iscollectedbyTEPCOandstoredonsiteinspecialtankstopreventitfromreachingtheenvironmentinitscurrentstate(seeFigure1.2).However,asthecontaminatedwaterishighlyradioactive,thestorageoflargequantitiesonsitehasledtohigherdosesforworkersonsiteanddifficultiesforTEPCOinreachingthesiteboundarydosetargetof1mSvperyear.ThesechallengesledTEPCOtodeveloptheAdvancedLiquidProcessingSystem(ALPS)whichisusedtoremovemostoftheradioactivecontaminationfromthewaterandthusreducethedosetoworkersfromthisstoredwater.Additionally,TEPCOhasbeenworkingtoreducetheamountofcontaminatedwaterproducedeachday.Variouswatermanagementtechniqueshavebeendeployed,andimplemented,includingtheinstallationofadditionaltreatmentsystemsandstoragetanks,asub-drainsystem,andtheinstallationofseasideimpermeablewalls(seeFigure1.1).Additionally,uncontaminatedgroundwaterfromuphillofthedamagedfacilitiesisbeingroutedaroundthefacilitiesandintotheocean.Inaddition,acryogenic‘frozen’wallaroundthereactorbuildingsandontheseasidewasconstructedtopreventfurtherwateringress.Allofthesemeasureshavehelpedtoreducetheproductionofcontaminatedwaterfromapproximately540m3perdayto90m3perday[2].LandsideImpermeableWallGroundwaterbypassSeasideimpermeablewallGroundwaterdrainGroundwaterlevelsSubdrainUpperpermeablelayerLowerpermeablelayerLow-permeablelayerLow-permeablelayerGroundwaterGroundwaterSeawaterpipingtrenchOceanReactorbuildingsTurbinebuildingsFigure1.1.GroundwaterflowthroughtheFDNPS3Figure1.2.StoragetanksforcontaminatedwateratFDNPSDescriptionoftheAdvancedLiquidProcessingSystemandOtherTreatmentSystemsAsnotedpreviously,contaminatedwaterstoredonsiteistreatedtoremovemostoftheradioactivecontent,exceptfortritium,whichcannotberemovedbytheALPSsystem,oranyotherindustrialscalesystem(basedonexistingtechnology)giventhevolumeofwaterandlowtritiumconcentrationsinvolved.Multiplestepsareinvolvedinthetreatmentprocess,asshowninFigure1.3.PriortobeingtreatedbytheALPSsystem,thecontaminatedwaterhascaesiumandstrontiumremovedperiodicallythroughtheKURIONandSARRYsystems;caesiumandstrontiumaccountformostoftheradioactivityfromthecontaminatedwater.Then,whenthewaterisnolongerintendedtobeusedforcoolingthefueldebris,itissentforALPStreatmentwhere62additionalradionuclidesareremoved(seeFigure1.4).ItisimportanttonotethattheALPStreatmentprocessdoesnotremoveallradioactivematerial.Smallamountsofdifferentradionuclidesremaininthewater(althoughtheyarewellbelowregulatorylimits)evenaftertreatment,andtritiumisnotremovedbytheALPSsystematall.TheALPSsystemisfundamentally,apumpingandfiltrationsystemwhichusesaseriesofchemicalreactionstoremove62radionuclidesfromthecontaminatedwater.TheradioactivematerialremovedfromthewateriscapturedinfilterswhicharestoredonsiteinspecialcontainerscalledHighIntegrityContainers(HIC).AftergoingthroughtheALPStreatmentprocess,thewateriscalled“treatedwater”or“ALPStreatedwater”andisthenstoredinlargetanksonsite(approximately1,000m3each).Thesetanksareallgivenalphanumericcodestouniquelyidentifythem,suchasK4B.Currentlythereareover1000tanksonsiteatFDNPS.4rainwatergroundwaterfilteredwater(usedascoolant)reactorbuildingscontaminatedwaterremovesaltcontentDesalinationfacilityreduceCaesiumandStrontiumCaesium/Strontiumfilteringdevice(KURION)SecondCaesium/StrontiumFilteringDevice(SARRY)StrontiumTreatedWaterStorageTanksRemovemostoftheradioactivematerialsMulti-nuclideRemovalFacility(ALPS)ImprovedMulti-nuclideRemovalFacility(ImprovedALPS)HighPerformanceMulti-nuclideRemovalFacility(HighPerformanceALPS)TreatedWaterviaMulti-nuclideremovalfacility(ALPS)StorageTanksFigure1.3.ALPStreatmentprocessRadioactivematerialsremovedHighIntegrityContainers(HIC)TransportedtothetemporarystoragefacilitiestobestoredContaminatedwaterwithoil,Cesium,andStrontiumreducedthroughtheexistingwatertreatmentfacilitiesIroncoprecipitationtreatmentfacilityCarbonatecoprecipitationtreatmentfacility14towersadsorptionreplacementtype2towersadsorptionColumntypeALPStreatedwaterwith62kindsofnuclidesremoved(storedintanks,etc..)AdsorptionTowerPre-treatmentfacilitiesALPS(Multi-nuclideRemovalFacility)Figure1.4.DetailsofALPStreatmentprocesstoremoveradionuclidesGovernmentofJapan’sdecisiononthedisposalofthetreatedwater.InDecember2013,theCommitteeonCountermeasuresforContaminatedWaterTreatmentdraftedadocumententitled“PreventativeandMulti-layeredMeasuresUtilizingEnhancedComprehensiveRiskManagementforContaminatedWaterTreatmentatTokyoElectricPowerCompany’sFukushimaDaiichiNuclearPowerStation.”ThedocumentidentifiedthatissueswouldremainunresolvedconcerningthehandlingoftheALPStreatedwaterevenifvariouscountermeasuresweretaken,including“removing”thecontaminationsource,“redirecting”groundwaterfromthecontaminationsourceand“preventingleakage”ofcontaminatedwaterduetothestorageoftheALPStreatedwaterwhichwouldincreasethenumberoftankstobemanaged,resultinginthepotentialformoreleakageeventstooccur.5Inaddition,inDecember2013,anIAEAReviewMissionprovidedanadvisorycommentconcerningthehandlingoftheALPStreatedwater,that“alloptionsshouldbeexamined.”Accordingly,toassessavarietyofoptionsforthehandlingoftheALPStreatedwater,theTritiatedWaterTaskForce,comprisedoftechnicalexpertsfromoutsidetheGovernmentofJapan,wasestablishedundertheCommitteeonCountermeasuresforContaminatedWaterTreatment.Asaresult,theTritiatedWaterTaskForcebeganareviewinDecember2013andpublishedareportinJune2016.InSeptember2016,theCommitteeonCountermeasuresforContaminatedWaterTreatmentdecidedtoestablishanALPSsubcommittee,comprisedoftechnicalexpertsfromoutsideoftheGovernmentofJapan,todiscussthehandlingoftheALPStreatedwaterfromallviewpoints,includingsocialperspectives.TheALPSsubcommittee’sintentwastoprovideanindependentpointofviewfortheGovernmentofJapantoutilizewhendecidinghowtodisposeoftheALPStreatedwater,alsotakingintoaccounttheopinionsofawiderangeofthepartiesconcerned.TheTritiatedWaterTaskForceandtheALPSsubcommitteeconductedcomprehensivediscussionsonthismatteroveraperiodofmorethansixyears.TheALPSsubcommitteeorganizedmanyexplanatorymeetingsandpublichearingstohearopinionsabouttheALPStreatedwaterdisposalpathwayandconcerns.Themaintopicsanalysedbythesubcommitteewere:thereviewofthecurrentconditionsoftheALPStreatedwaterincludingtheprogressofcontaminatedwatermanagementandgenerationandstorage,thecharacteristicsoftheALPStreatedwater,thestatusofdisposalofradioactivewasteincludingtritiuminandoutsideJapan,theexaminationondisposalpaths,duration,amount,timingandmonitoringoftherelease,reputationaldamageandcountermeasuresinthecaseofthedisposaloftheALPStreatedwater.InFebruary2020,anALPSSubcommitteereportwasreleased[3].Thereportconcludedthat,ofthefivedisposalmethodsanalysedindetail(outofmanymoretheoreticaloptionsconsidered),vaporreleaseandcontrolleddischargesintotheseawerethemostpracticaloptionstakingintoaccountsafetyconcerns,theexistingtechnologyavailable,andtimeconstraints.Thereportalsoconcludedthatdischargeintotheseacouldbe“implementedmorereliably,withrespecttomitigatingenvironmentalandhumanhealthimpacts,giventhatthisdischargemethodiscommonlyusedamongnuclearplantsaroundtheworld;dischargefacilitieshavepositivetrackrecordsforsafety;andcontrolleddischargesintotheseacanbemonitoredmostaccurately.”InresponsetotheALPSSubcommitteereport,inAprilofthesameyear,thereportfromanIAEAdecommissioningmission[4]statedthat“therecommendationsmadebytheALPSSubcommitteearebasedonasufficientlycomprehensiveanalysisandonasoundscientificandtechnicalbasis”andnotedthatthetwooptions(vaporreleaseanddischargeintothesea)are“technicallyfeasible”.InApril2021,theGovernmentofJapanannouncedtheBasicPolicyonHandlingofALPSTreatedWaterattheTokyoElectricCompanyHoldings’FukushimaDaiichiNuclearPowerStation.,TheBasicPolicycontainstheGovernmentofJapan’sbasicpremise,relevantbackgroundandanoutlineforpursuingdischargeofALPStreatedwaterintothesea.IntheBasicPolicytheGovernmentofJapannotes:“InordertosafelyandsteadilyproceedwithdecommissioningandmanagementofcontaminatedwaterandtreatedwateratFDNPS,basedontheALPSSubcommitteereportandopinionsreceivedfrompartiesconcerned,theALPStreatedwaterwillbedischargedontheconditionthatfullcompliancewiththelawsandregulationsisobserved,andmeasurestominimizeadverseimpactsonreputationarethoroughlyimplemented.”TheBasicPolicyfurthernotesthat“…[the]dischargeofALPStreatedwaterintotheseawillbeimplementedatFukushimaDaiichiNPS,onthepremisetomakebesteffortstominimizetherisksbytakingmeasuressuchaspurificationanddilutionbasedontheALARAprinciple,understrictcontrol.”Insupportofthisdecision,theBasicPolicyprovidesbackgroundandsupportingjustificationsuchastheimportanceofriskreduction,protectingpeopleandtheenvironmentandensuringthatreconstructionofFukushimacanbesupported.Furthermore,theBasicPolicyhighlightstheworkoftheInter-Ministerial6CouncilinassessingothertechnologiesforhandlingandmanagingALPStreatedwaterstoredattheFukushimaDaiichiNuclearPowerStation.ThecurrentapproachoutlinedintheBasicPolicyistoconductaseriesofcontrolleddischargesofALPStreatedwaterintothesea(‘batchdischarges’)overaperiodofapproximately30years.FacilitiesfordischargingALPStreatedwaterAdiagramofthefacilitiesfordischargingALPStreatedwaterintothesea(Figure1.5).Thefacilitiesarecomposedoffourmaincomponents.Abriefsummaryisincludedbelow,andamoredetaileddescriptionisincludedinPart3(Section3.2)ofthisreport.•Themeasurementandconfirmationfacility:Thewatertobedischargedisreceivedbythemeasurementandconfirmationfacilityandishomogenizedbyinstalledagitators.ThewateristhensampledbyTEPCOandsenttoonsiteanalyticallaboratories.ThewatersamplesareanalysedforawiderangeofradionuclidesandTEPCOverifieswhethertheALPStreatedwatercontainedinthetanksarereadyfordischarge(i.e.,thesmallamountofradioactivematerialleftinthewater,exceptfortritium,meetsdomesticregulatorylimits).•Thetransferfacility:Onceverifiedbyanalysis,thewateristransferredbypumpsandpipingfromthemeasurementandconfirmationfacilitytothedilutionfacility.Thepumps,piping,valves,andotherengineeredcontrolsassociatedwiththisstepareconsideredthetransferfacility.•Thedilutionfacility:Furtherdownstream,ALPStreatedwaterismixedwithseawaterinalargesectionofpipingcalledaheader.Theseawaterheaderreceivesseawaterfromthreepipinglineswhichareeachconnectedtoaseawaterpump.TheUnit5intakechannelisusedasthesourceoftheseawater.•Thedischargefacility:whichconsistsofthedischargeverticalshaft,dischargetunnelanddischargeoutlet.ThedischargeofALPStreatedwateroccursthroughatunnelrunningundertheseabedaboutonekilometreoffthecoast.Figure1.5.AdiagramofthefacilitiesfordischargingALPStreatedwaterintothesea7GovernmentofJapanRequestandIAEA’sResponseInApril2021,JapanannounceditsBasicPolicyandsoonafter,theJapaneseauthoritiesrequestedassistancefromtheIAEAtomonitorandreviewthoseplansandactivitiesrelatingtothedischargeofthetreatedwatertoensuretheywillbeimplementedinasafeandtransparentway,andtheywillbeconsistentwiththeIAEA’sinternationalsafetystandards.TheIAEA,inlinewithitsstatutoryresponsibility,acceptedtherequestmadebyJapan.InJuly2021,theIAEAandtheGovernmentofJapansignedtheTermsofReferenceforIAEAAssistancetoJapanonReviewofSafetyAspectsofALPSTreatedWateratTokyoElectricPowerCompanyHoldings,Inc.(TEPCO)FukushimaDaiichiNuclearPowerStation(FDNPS).ThesetermsofreferencesetoutthebroadframeworkthattheIAEAwillusetoimplementitsreview.SucharequesttotheIAEA,anditsacceptancebytheIAEA,isinaccordancewiththeIAEAfunctiondescribedinArticleIII.A.6oftheIAEAStatute.InSeptember2021,theIAEAsentateamtoTokyo,formeetingsanddiscussionstofinalizetheagreementonthescope,keymilestonesandapproximatetimelinefortheAgency’sreview.TheteamalsotravelledtotheFDNPStodiscusstechnicaldetailswithexpertsatthesiteandtoidentifykeyactivitiesandlocationsofinterestfortheAgency’sreview.ToimplementtheIAEA’sreviewinafullytransparentandinclusivemanner,theIAEADirectorGeneralestablishedaTaskForce.TheTaskForceoperatesundertheauthorityoftheIAEAandischairedbyaseniorIAEAofficial.TheTaskForceincludesexpertsfromtheIAEASecretariatalongsideinternationallyrecognizedindependentexpertswithextensiveexperiencefromawiderangeoftechnicalspecialtiesfromArgentina,Australia,Canada,China,France,theMarshallIslands,theRepublicofKorea,theRussianFederation,theUnitedKingdom,theUnitedStatesandVietNam.TheseindependentexpertsprovideadvicetotheIAEAandserveontheTaskForceintheirindividualprofessionalcapacitytohelpensuretheIAEA’sreviewiscomprehensive,benefitsfromthebestinternationalexpertiseandincludesadiverserangeoftechnicalviewpoints.TheIAEAprimarilyconducteditsreviewthroughtheanalysisofdocumentationprovidedbyTEPCO,NRA,andMETI;andholdingreviewmissionstofurtherclarifyquestionsandtoaskforadditionalmaterials.TheIAEAalsoconductedonsitevisitstoFDNPSperiodicallythroughout2021,2022,and2023.FivereviewmissionstoJapanwerecarriedoutbetweenFebruary2022andJune2023andtheseandthecorrespondingtechnicalreportsaredetailedinAnnex1.Thereportsissuedafterthefirstfourreviewmissionsserveasprogressreportsandfinalconclusionsareonlypresentedforthefirsttimeinthiscomprehensivereport.Atthestartofthereview,theGovernmentofJapanandTEPCOprovidedbackgroundmaterialswithinformationpertainingtotheproposeddischargeofALPStreatedwater.Subsequently,additionalmaterialswereprovideduponrequestbytheTaskForce,orwhenreadyforsubmissionbyTEPCOtotherelevantJapaneseauthorities(e.g.,NRA).ThisinformationwasreviewedbytheTaskForcemembersandformedthebasisforthereviewmissionswithrelevantauthorities.ThepurposeofthereviewmissionswastoreviewthereferencematerialssubmittedbytheGovernmentofJapanorTEPCO,seekclarificationontechnicalissues,requestadditionalinformationandobserveon-siteactivities,asappropriate.TheIAEAhasexaminedkeysafetyelementsofJapan’splan,includingthefollowing:•Theradiologicalcharacterizationofthetreatedwatertobedischarged.•Thesafety-relatedaspectsofthetreatedwaterdischargeprocess,includingtheequipmenttobeusedandthecriteriatobeappliedandobservedforoperations.8•Theassessmentoftheradiologicalenvironmentalimpactrelatedtoensuringtheprotectionofpeopleandtheenvironment.•Theenvironmentalmonitoringassociatedwiththedischarge.•Theregulatorycontrol,includingauthorization,inspectionandongoingassessmentofthedischargeplan.TheIAEA’sreview(asshowninFigure1.6)isorganizedintothefollowingthreemajorcomponentstoensureallkeysafetyelementsareadequatelyaddressed:•AssessmentofProtectionandSafety–ThiscomponentisfocusedonreviewingtechnicalaspectsoftheImplementationPlan,radiologicalenvironmentalimpactassessment(REIA),andothersupportingmaterialspreparedbyTEPCOaspartoftheirsubmissionforregulatoryapprovalofthedischargeofALPStreatedwater.ThiscomponentprimarilyinvolvesTEPCOandtheMinistryofEconomy,Trade,andIndustry(METI)andlookattheexpectedactionstobeperformedbyTEPCOthroughouttheprocess,asdefinedintherelevantIAEAinternationalsafetystandards.•RegulatoryActivitiesandProcesses–ThiscomponentisfocusedonassessingwhethertheNuclearRegulationAuthority’s(NRA)reviewandapprovalprocessisconductedinaccordancewiththerelevantIAEAinternationalsafetystandards.ThiscomponentprimarilyinvolvesNRAastheindependentregulatorybodyresponsiblefornuclearsafetywithinJapan;itisfocussedonlyontheregulatoryaspectsrelevantforNRA’sreviewofthedischargeofALPStreatedwaterfromtheFukushimaDaiichiNuclearPowerStation.•IndependentSampling,DataCorroborationandAnalysis–ThiscomponentincludesallactivitiesassociatedwiththeIAEA’sindependentsamplingandanalysisthatisandwillbeperformedtocorroboratethedatafromTEPCOandtheGovernmentofJapanassociatedwiththedischargeofALPStreatedwater.SamplesareanalysedbyIAEAlaboratoriesaswellasindependentthird-partylaboratories.Additionally,thiscomponentalsoincludesthecorroborationofoccupationalexposure.ComponentsofIAEA’sReviewAssessmentofProtectionandSafety•ReviewTEPCO’simplementationplanandsupportingdocumentation.•Focusontechnicalconsiderationssuchassourcecharacterization,safetyrelatedaspectsoftheapproach,occupationalradiationexposure,radiologicalenvironmentalimpactassessment.RegulatoryActivitiesandProcess•ReviewNRAactionsandprocessesrelevanttotheproject•Focusonsafetyobjectives,regulatoryrequirements,regulatoryassessment,regulatoryinspections.IndependentSampling,DataCorroborationandAnalysis•IndependentsamplingandanalysistocorroboratedatafromJapan.•Performanalysisofsourcetermandenvironmentalsamples.•Corroboratemonitoringresultsforoccupationalexposure.Figure1.6.ComponentsoftheIAEAReviewAdditionalinformationontheIAEA’sreview,aswellasbackgroundinformation,documents,reports,andotherpublicationscanbefoundonlineatthededicatedwebsitefortheIAEA’sFukushimaALPSreview[5].91.2.TheComprehensiveReportThepurposeofthiscomprehensivereportistopresenttheIAEA’sfinalconclusionsandfindingsfromitstechnicalreviewtoassesswhethertheplantodischargetheALPStreatedwaterintotheseaoverthecomingdecadesisconsistentwiththeIAEA’sinternationalsafetystandards.ThescopeofthisreportmatchesthescopeoftheIAEA’ssafetyreview,howeveradditionalbackgroundmaterialregardingthehistoryoftheaccidentattheFDNPSandotherassociateddetailsarealsoincluded.TheIAEA’ssafetyreviewisfocusedonassessingwhethertheactionsofTEPCOandtheGovernmentofJapantodischargetheALPStreatedwateroverthecomingdecadesisconsistentwiththeinternationalsafetystandards.Furthermore,theIAEA’sreviewisfocusedonassessingwhetherJapan’schosenmethodforhandlingALPStreatedwater(i.e.,controlleddischargesintothesea)isconsistentwithinternationalsafetystandardsanddoesnotassessthefeasibilityofotherpotentialmethods.Finally,whennecessary,explanationsregardingthebroaderdecommissioningeffortwereincludedinthisreport;however,ingeneral,thesite’scomprehensivedecommissioningactivitieswereconsideredoutsidethescopeoftheIAEA’soverallsafetyreview.Thereportconsistsoffiveparts:•Part1coversintroductionandprovidessomebackgroundmaterialonthesourceofthecontaminatedwater,theALPStreatmentprocess,thefacilitiesfordischargingtheALPStreatedwater,theJapaneseBasicPolicyforhandlingtheALPStreatedwater,andtheinternationalsafetystandards.•Part2coverstheassessmentofconsistencywiththetensafetyprinciplessetoutintheIAEASafetyFundamentals,inalanguagethatisunderstandabletoallreaders,aswellasthosewithanon-technicalbackground.•Part3coverstheassessmentofconsistencyofthedischargeofALPStreatedwaterintotheseawiththerelevantSafetyRequirementsintheinternationalsafetystandards.Thereareseventopicscoveredintherevieware:oCharacterizationofthedischargeandsourceterm.oSafetyrelatedaspectsofsystemsandprocessesforcontrollingdischarges.oRadiologicalenvironmentalimpactassessment.oRegulatorycontrolandauthorizationofdischarges.oSourceandenvironmentalmonitoringprogrammes.oInvolvementofinterestedparties.oOccupationalradiationprotection.•Part3iswrittenintechnicallanguageanddescribestheIAEA’sreviewandassessmentandsetsouttheconclusionsoftheassessmentforeachofthesetopics.•Part4coverstheIAEA’scorroborationactivitiestoevaluatetheaccuracyofdataprovidedbyTEPCOandtheJapaneseauthorities.TheIAEA’sindependentsampling,datacorroboration,andanalysisactivitiesaredescribedinPart4.•Part5includesadditionalinformationontheoverallnextstepstheIAEAandtheTaskForcewilltakeundertheIAEA’ssafetyreview,whichwillcontinueformanyyears.101.3.TheIAEAinternationalsafetystandardsFigure1.7.HierarchyofIAEASafetyStandardsTherelevantinternationalsafetystandardsareusedaspartoftheIAEA’ssafetyreview(asdetailedinAnnex2).Thesedocumentsarestandardsofsafetyforprotectionofhealthandminimizationofdangertolifeandproperty,includingsuchstandardsforlabourconditions.TheIAEA’sSafetyStandardsconsistofthreesetsofpublications:theSafetyFundamentals,theSafetyRequirementsandtheSafetyGuides.Whilethefirstoneoftheseestablishesthefundamentalsafetyobjectiveandprinciplesofprotectionandsafety,thesecondprovidetherequirementsthatmustbemettoensuretheprotectionofpeopleandtheenvironment,bothnowandinthefuture.TheSafetyGuidesproviderecommendationsandguidanceonhowtomeettherequirements.Theinternationalsafetystandardsarecosponsoredinconsultationand,whereappropriate,incollaborationwiththecompetentorgansoftheUnitedNationsandwiththespecializedagencies.SafetyFundamentalsSafetyFundamentalspresentthefundamentalsafetyobjectiveandprinciplesofprotectionandsafety,andprovidethebasisforthesafetyrequirements.TheIAEASafetyFundamentalsarejointlysponsoredbytheEuropeanAtomicEnergyCommunity(Euratom),theFoodandAgricultureOrganizationoftheUnitedNations(FAO),theInternationalAtomicEnergyAgency(IAEA),theInternationalLabourOrganization(ILO),theInternationalMaritimeOrganization(IMO),theOECDNuclearEnergyAgency(OECD/NEA),thePanAmericanHealthOrganization(PAHO),theUnitedNationsEnvironmentProgramme(UNEP)andtheWorldHealthOrganization(WHO).ThetenFundamentalSafetyPrinciplesconstitutethebasisonwhichtoestablishsafetyrequirementsfortheprotectionagainstexposuretoionizingradiation.Thesafetymeasurestakentoensuretheprotectionofhumanlifeandhealthandtheenvironmentagainstexposuretoradiationaredetailedandtechnicallycomplex.Totheextentpossible,however,theFundamentalSafetyPrincipleshavebeendraftedinlanguagethatisunderstandabletothenon-specialistreader.Theintentionistoconveythebasisandrationaleforthesafetystandardsforthoseatseniorlevelsingovernmentandregulatorybodiesandthosewho,whileresponsibleformakingdecisionsconcerningtheusesofnuclearenergyandradiationsources,maynotbespecialistsinnuclearorradiationscienceandtechnologyorinradiationprotectionandsafetymatters.TheapplicationoftheFundamentalSafetyPrincipleswillfacilitategreaterconsistencybetweenthearrangementsofdifferentStatesanditisthereforedesirablethatallStatesadheretoandadvocatetheseprinciples.FundamentalSafetyPrinciplesSafetyRequirementsSafetyGuides11SafetyRequirementsAnintegratedandconsistentsetofSafetyRequirementsestablishestherequirementsthatmustbemettoensuretheprotectionofpeopleandtheenvironment,bothnowandinthefuture.TherequirementsaregovernedbytheobjectiveandprinciplesoftheSafetyFundamentals.Iftherequirementsarenotmet,measuresmustbetakentoreachorrestoretherequiredlevelofsafety.Theformatandstyleoftherequirementsfacilitatetheirusefortheestablishment,inaharmonizedmanner,ofanationalregulatoryframework.Requirements,includingnumbered‘overarching’requirements,areexpressedas‘shall’statements.Manyrequirementsarenotaddressedtoaspecificparty,theimplicationbeingthattheappropriatepartiesareresponsibleforfulfillingthem.OfparticularrelevancetotheIAEA’ssafetyreview,GSRPart3:RadiationProtectionandSafetyofRadiationSources:InternationalBasicSafetyStandardsisjointlysponsoredbyEuropeanCommission,FAO,IAEA,ILO,OECD/NEA,PAHO,UNEPandtheWHO.SafetyGuidesSafetyGuidesproviderecommendationsandguidanceonhowtocomplywiththesafetyrequirements,indicatinganinternationalconsensusthatitisnecessarytotakethemeasuresrecommended(orequivalentalternativemeasures).TheSafetyGuidespresentinternationalgoodpractices,andincreasinglytheyreflectbestpractices,tohelpusersstrivingtoachievehighlevelsofsafety.Requirements,includingnumbered‘overarching’requirements,areexpressedas‘shall’statements.Manyrequirementsarenotaddressedtoaspecificparty,theimplicationbeingthattheappropriatepartiesareresponsibleforfulfillingthem.TherecommendationsprovidedinSafetyGuidesareexpressedas‘should’statements.ManyIAEASafetyGuidesrelevantforthissafetyreviewarecosponsoredbyUNEP.Figure1.8.TheInternationalSafetyStandardsFollowingadecisionoftheUnitedNationsGeneralAssembly(UNGA),thelevelsandeffectsofionizingradiationareestimatedbytheUnitedNationsScientificCommitteeontheEffectsofAtomicRadiation(UNSCEAR).TheUNSCEARestimatesareprovidedyearlytoUNGAandcanbeconsideredasthe12scientificandepistemologicalbasisoftheInternationalSafetyStandards.Furthermore,aninternationallyrecognizedparadigmormodelhasbeenelaboratedbytheInternationalCommissiononRadiologicalProtection(ICRP)sinceitsfoundationsin1928.TheICRPisanon-governmentalcharityprovidingrecommendationsonradiationprotectionthathasbeenfollowedbyprofessionals,institutionsandgovernmentsallovertheworld.FollowingaformaldecisionoftheIAEAintergovernmentalpolicymakingorgans[6]theIAEA’sSafetyStandardsaredevelopedtakingintoaccounttherecommendationsoftheICRP;thelatestgeneralrecommendationsofICRPcanbefoundontheirwebsiteandarepublishedregularly.13ASSESSMENTOFCONSISTENCYWITHTHEFUNDAMENTALSAFETYPRINCIPLESTheSafetyFundamentalsstatethatthefundamentalsafetyobjectiveofprotectingpeople—individuallyandcollectively—andtheenvironmenthastobeachievedwithoutundulylimitingtheoperationoffacilitiesortheconductofactivitiesthatgiverisetoradiationrisks.Toensurethatfacilitiesareoperated,andactivitiesconductedsoastoachievethehigheststandardsofsafetythatcanreasonablybeachieved,measureshavetobetaken:•Tocontroltheradiationexposureofpeopleandthereleaseofradioactivematerialtotheenvironment.•Torestrictthelikelihoodofeventsthatmightleadtoalossofcontroloveranuclearreactorcore,nuclearchainreaction,radioactivesourceoranyothersourceofradiation.•Tomitigatetheconsequencesofsucheventsiftheyweretooccur.Thefundamentalsafetyobjectiveappliesforallfacilitiesandactivities,andforallstagesoverthelifetimeofafacilityorradiationsource,includingplanning,siting,design,manufacturing,construction,commissioning,andoperation,aswellasdecommissioningandclosure.Thisincludestheassociatedtransportofradioactivematerialandmanagementofradioactivewaste.Tensafetyprincipleshavebeenformulated,onthebasisofwhichsafetyrequirementsaredevelopedandsafetymeasuresaretobeimplementedinordertoachievethefundamentalsafetyobjective.Thefundamentalsafetyprinciplesformafoundationthatisapplicableinitsentirety,althoughinpracticedifferentprinciplesmaybemoreorlessimportantinrelationtoparticularcircumstances.Therefore,inordertoverifythatthefundamentalsafetyobjectivewasachieved,theTaskForceconsideredhowthetenfundamentalsafetyprinciplesappliedtothedischargeoftheALPStreatedwater.TheTaskForcediscussedalltenfundamentalsafetyprinciplestoconsiderhowtheactionsandplansoftheGovernmentofJapanandTEPCOaddressedeach.PART2142.1.ResponsibilityforSafetyTheprimeresponsibilityforsafetymustrestwiththepersonororganizationresponsibleforfacilitiesandactivitiesthatgiverisetoradiationrisks.Thisprinciplestatesthattheorganizationresponsibleforafacilitythatgivesrisetoradiationriskshastheprimeresponsibilityforsafety.Thisresponsibilitycannotbedelegatedtoanotherorganization,althoughotherorganizationssuchasdesigners,manufacturersandconstructors,andcontractors,alsohavesomeresponsibilitiesforsafety,astheiractivitiesorproductsmaybeofsignificanceforsafety.However,theprimeresponsibilityforsafetycannotbedelegated.InJapan,theAtomicEnergyBasicAct,theReactorRegulationActandtheRadioisotopeRegulationActassignresponsibilitiesforsafetytolicenseesforallactivitiesinvolvingnuclearmaterialandisotopes.AftertheaccidentatFDNPS,theReactorRegulationActwasamendedtobetterreflecttheprimeresponsibilityforsafetyofthelicensees.TheArticlesintroducedrequirethatlicenseesofnuclearpowerplantsshallperiodicallyre-evaluatethesafetyoftheirfacilitiesandtoimprovethesafety,toenhanceeducationonoperationalsafety,andtotakeanyothernecessarymeasuresforpreventingdisasters.Inaddition,inArticle6,paragraph(9)oftheSupplementaryProvisionsoftheNRAEstablishmentActexplicitlystatesthat“Nuclearoperatorsshallbedeeplyawarethattheyhaveprimeresponsibilityforensuringthesafetyoftheirnuclearfacilities……”.Theresponsibilityforsafetyremainswiththelicenseewhenitcontractsforproductsandservicesfromthirdparties.NoneoftheActsinJapanallowsthedelegationoflicensees’responsibilitiestootherparties.LicenseesareresponsibleforverifyingthattheproductsandservicessuppliedtothembythirdpartiescomplywiththeapplicableLaw.Basedonitsreviewofrelevantdocumentsanddiscussionsheldduringmeetingsandmissions,theTaskForcehasnotedthatTEPCOhastheprimeresponsibilityforsafetyforthemanagementofthedischargeofALPStreatedwateratFDNPSandislicensedbyNRAwhoisdesignatedbytheGovernmentofJapanashavinglegalauthoritytoconducttheregulatoryprocess.TEPCOisresponsibleforensuringthesafetyoftheALPSfacility,andtheassociatedequipment;establishingproceduresandarrangementstomaintainsafetyunderallconditions;ensurethesafecontrolofallradioactivematerialthatisusedandstoredonsite;andprovideadequatetrainingandinformationtoemployees.TEPCOhaspreparedanImplementationPlan[17]foractivitiesatFDNPS,whichincludesthedischargeofALPStreatedwater.TheImplementationPlan,whichisreviewedandapprovedbytheNRA,hassupportedtheTaskForceinbetterunderstandinganumberofimportanttechnicalpoints.Furthermore,theIAEAnotesthefollowing:1.TEPCOhaspresentedinformationontheradiologicalcharacterizationofthetreatedwateratvariousstagesofthedischargeprocess.2.TEPCOhasdevelopeddesigncriteriaforthedischargefacilities,thattakesintoaccountredundantanddiversesafetyfeaturestodetectandpreventeventsthatcouldleadtotheunintendedreleaseofALPStreatedwatertotheenvironment.3.TEPCOhascarriedoutasafetyassessmentforthedischargeofALPStreatedwatertothesea,inaccordancewiththerequirementsestablishedbyNRA.4.TEPCOhascarriedoutaradiologicalenvironmentalimpactassessment.5.TEPCOispartoftheComprehensiveRadiationMonitoringProgramme[7]fortheenvironmentalmonitoringassociatedwiththedischargeofALPStreatedwater.15Conclusions•UnderthelegalandregulatoryframeworkestablishedinJapan,TEPCOhastheprimeresponsibilityforthesafetyofthedischargeoftheALPStreatedwaterfromFDNPS.2.2.RoleoftheGovernmentAneffectivelegalandgovernmentalframeworkforsafety,includinganindependentregulatorybody,mustbeestablishedandsustained.Thisprinciplestatesthataproperlyestablishedlegalandgovernmentalframeworkprovidesfortheeffectiveregulationoffacilitiesandactivitiesthatgiverisetoradiationrisksandfortheclearassignmentofresponsibilities.Thegovernmentisresponsibleforthedevelopmentoflegislation,regulationsandotherregulatorystandardsandguidesthatarenecessarytofulfilitsnationalresponsibilitiesandinternationalcommitmentsfortheregulatorycontroloffacilitiesandactivitiesthatgiverisetoradiationrisks,andfortheestablishmentofanindependentregulatorybody.Theregulatorybodyshallsetupappropriatemeansofinformingpartiesinthevicinity,thepublicandotherinterestedparties,andthemediaaboutthesafetyaspectsoffacilitiesandactivities,andaboutregulatoryprocesses.Theregulatorybodyshallalsoconsultpartiesinthevicinity,thepublicandotherinterestedpartiesinanopenandinclusiveprocess.AsaconsequenceoftheaccidentatFDNPS,JapanfundamentallychangeditsregulatorysystemfornuclearsafetyandestablishedtheNuclearRegulationAgency(NRA)asanewindependentregulatorybody.UndertheNRAEstablishmentAct,NRAhassoleresponsibilityforregulatingnuclearsafety,nuclearsecurity,safeguardsbasedoninternationalcommitments,andtheuseofradioactiveisotopesandradiationmonitoring.NRAengagesinindependentdecision-makingconcerningregulatoryactivities,suchaspermits,approvalsandinspections,withouttheinvolvementoftheauthoritiestaskedwithpromotingnuclearenergy.TheNRAisanexternalbureauoftheMinistryoftheEnvironment,andthereforeclearlyseparatedfromMETIwhoholdsjurisdictionoverthepromotionanduseofnuclearenergy.TheChairmanandCommissionersofNRAareappointedbythePrimeMinister,withtheconsentoftheDiet.TheNRAChairmanappointsthestaffoftheSecretariatofNRA.TheactivitiesofNRAarefinancedbythenationalbudget,withbudgetproposalsbeingsubmittedtotheMinistryofFinancebyNRA.AuthoritiestaskedwithpromotingnuclearenergyarenotinvolvedintheapprovalprocessoftheNRAbudget.ThelegislativeandregulatoryframeworkinJapanisbasedonafive-levelsystem:1.BasicActsdefinethebasiclegalframeworkandpolicyforthesafeuseandregulatoryoversightofnuclearenergyanddisastercontrolmeasures.TheBasicActsneedtobeapprovedbythenationalDiet.a.Intheareaofnuclearsafety,TheAtomicEnergyBasicActisthemostimportantpieceoflegislation.Itdefinesthebasicprinciplesofnuclearenergyuseandsafety,andthescopeofthesubsequentspecificActs.b.TheBasicActonDisasterControlMeasures,coveringalltypesofdisaster,definestheframeworkforemergencypreparednessandresponse.162.ActsimplementtheframeworkdefinedbytheBasicActsandformthemainlegalprovisionsforthedevelopmentandutilizationofnuclearenergy,andthebasesforsafetyregulation,authorizationandinspectionofnuclearfacilities.ActsneedtobeapprovedbythenationalDiet.a.TheNRAEstablishmentActstipulatesNRAasanuclearregulatorybodyandprovidesdetailsonitsauthorityandresponsibilities.b.TheReactorRegulationActprovidesforregulationsonallnuclearfacilitiesandactivitiesinordertoprotectthepopulationandtheenvironmentfromharmfuleffectsofradioactivityandmakesprovisionforregulationsovercontrollednuclearmaterials,aswellassecuringtheuseofnuclearenergyforpeacefulpurposes.c.TheRadioisotopeRegulationActimposesregulationsontheuse,selling,rental,otherhandlingofradionuclides,useofradiationgeneratingapparatus,wastemanagementandotherhandlingofobjectscontaminatedbyradionuclidesorradiationemittedfromradiationgeneratingapparatus.d.TheNuclearEmergencyActstipulatestheresponsibilityofnuclearoperators,theprocedurefordeclaringanuclearemergency,theestablishmentofNuclearEmergencyResponseHeadquarters,andimplementationofemergencyresponseorothermeasuresrelatedtoaddressingnuclearemergency.3.CabinetOrdersareissuedbyCabinetanddonotneedtobeapprovedbythenationalDiet.CabinetOrdersprescribeparticularsentrustedbytheActs.4.MinisterialOrdersprescribedetailsasentrustedbytheActs.TheNRAcanissueMinisterialOrdersinaccordancewithArticle26oftheNRAEstablishmentAct.SomeoftheseOrdinancesarealsoreferredtoasNRAStandards.5.NRARegulatoryGuidesprovidefurtherparticularsorinterpretationoftheMinisterialOrdinances,acceptablemethods,conditionsetc.NRAsharedwiththeTaskForcetheinformationsharingandconsultationprocessesthattheyhavecarriedoutinrelationtotheImplementationPlan.AfterTEPCOsubmittedamendmentstotheImplementationPlantofacilitatethedischargeofALPStreatedwater,theNRAandTEPCOparticipatedinreviewmeetingstodiscussTEPCO’splans(seeAnnex3foratimelineofNRAreviewactivities).Thesereviewmeetingswereopentothepublic,bothforin-personattendanceandviaweb-streaming.Allmaterials,includingminutesofthemeetingsarepostedontheNRAwebsite.Additionally,theNRAprovidedanexplanationinbriefingsfortheNationalDiet,localgovernments,municipalities,pressconferences,andinternationalconferences,amongothers.TheTaskForcenotedglobalinterestinthedischargeofALPStreatedwaterandtheimportanceofprovidingevidence-basedinformationtodemonstrateprotectionofpeopleandtheenvironmentglobally.TheNRAprovideddetailsregardingthepublic’sinvolvementinthereviewoftheImplementationPlanandREIA,notingthatalargenumberofcommentswerereceivedwhichwereconsideredbyNRA.Conclusions•TheGovernmentofJapanhasestablishedalegalandregulatoryframeworkforfacilitiesandactivitiesthatgiverisetoradiationrisks,thatincludesthefacilitiesandactivitiesrelatedtothedischargeofALPStreatedwater.17•NRAhasbeenestablishedanindependentregulatorybody,withresponsibilitiesthatincluderesponsibilityfortheregulatorycontroloftheTEPCO’sfacilitiesandactivitiesforthedischargeofALPStreatedwater.•NRAhascarriedoutitsregulatoryresponsibilitiesinrelationtothedischargeofALPStreatedwater:NRAhasrequiredthatTEPCOapplyforaauthorizationtodischargeALPStreatedwater,NRAhasrevieweddocumentationsubmittedbyTEPCOinitsapplicationforalicence(e.g.,safetyassessmentandREIA),andNRAisconsideringallavailableinformationaspartoftheirregulatoryauthorizationprocessbeforeissuinganauthorizationtodischargetheALPStreatedwater.•NRAhasconsultedwiththepublicaspartofitsreviewoftheImplementationPlanandREIAandcommentswereconsidered.•NRAhasestablishedaninformationsharingprogramaboutitsregulatoryactivitiesregardingtheImplementationPlanandtheREIAforpeoplelivinginthevicinity,thepublicandotherinterestedparties,thatincludesinterestedpartiesinneighbouringcountries.2.3.LeadershipandManagementforSafetyEffectiveleadershipandmanagementforsafetymustbeestablishedandsustainedinorganizationsconcernedwith,andfacilitiesandactivitiesthatgiveriseto,radiationrisks.Thisprinciplefocussesontheeffectiveleadershipandmanagementforsafetyinorganizationsconcernedwithfacilitiesandactivitiesthatgiveriseto,radiationrisks.Thisincludestheorganizationresponsibleforthefacilityorfortheactivityandtheregulatorybodyandothercompetentauthorities.Theprinciplestatesthatthemanagementatalllevelsintheseorganizationsshalldemonstrateitscommitmenttotheestablishment,implementation,assessmentandcontinualimprovementoftheorganization’smanagementsystemandshallallocateadequateresourcestocarryouttheseactivities.Leadershipforsafetyincludestheorganization’svision,goals,strategies,plansandobjectives;byadvocatingforindividualcommitmenttotheprotectionofpeopleandtheenvironmentfromharmfuleffectsofionizingradiation,establishingbehaviouralexpectations,andfosteringastrongsafetyculture.Managementforsafetyincludesestablishingandapplyinganeffectivemanagementprocess.TheleadershipandmanagementforsafetyarethereforeoffundamentalimportancefortheorganizationsthathaveresponsibilitiesrelatingtothedischargeofALPStreatedwater.However,theTaskForcehasalsoacknowledgedthatthedischargeofALPStreatedwaterisoccurringwithinthelargerFDNPSandthereforefallsunderbroaderleadershipandmanagementstructuresatTEPCOandatNRA.TEPCO’sorganizationalstructureindicatesthattheALPSTreatedWaterProgramDepartmentisresponsibleforthedevelopmentimplementationofrelevantoversight,planning,andtechnicalaspectsoftheALPStreatedwaterdischargefacilities.ThereareothersupportingtechnicalDepartmentsinseveralfieldssuchasconstruction,maintenance,engineering,installations,trainingandmonitoringlaboratories.NRA’smanagementsystemdocumentstheworkprocessesofNRA,includingtheregulatoryprocessesforauthorizationandinspection.NRAsubjectsitsmanagementsystemtointernalauditstoensureit18remainscompliantwithitsrulesandtoidentifyopportunitiesforimprovement,e.g.proposalsmadebyNRAemployees.NRAhasorganizedstaffseminarsonsafetycultureandpromotestheneedforstafftorecognizetheneedtopromotesafetyculture,basedontherecommendationsoftheaccidentinvestigationcommitteesofFukushima-DaiichiNPP.Thisprinciplealsostatesthatsafetyhastobeassessedforallfacilitiesandactivities.Asafetyassessmentinvolvesthesystematicanalysisofnormaloperationanditseffects,ofthewaysinwhichfailuresmightoccurandoftheconsequencesofsuchfailures.Afacilitycanonlybeconstructedandcommissioned,oranactivitymayonlybeginonceithasbeendemonstrated,tothesatisfactionoftheregulatorybody,thattheproposedsafetymeasuresareadequate.TheTaskForcehighlightedthesignificantamount,andlevelofdetail,ofanalysesperformedbyTEPCOfortheconductofthesafetyassessment,itscomprehensiveapproach,aswellasthefactthatalargenumberofpotentialsinglefailureeventsweretakenintoconsiderationforthedevelopmentofthedesigncriteriaforthedischargeofALPStreatedwater.Inaddition,theTaskForcementionedduringpreviousmissions,theimportanceofmakingacomprehensiveassessmentconsideringallfailuremodesandidentifyingthedifferentinitiatorsthatmightleadtothedischargeofundilutedALPStreatedwater;theworkdonedocumentedintheimplementationplan.FurtherdetailsaboutthesafetyassessmentcanbefoundinPart3(Section3.2).Conclusions•LeadershipandmanagementforsafetywithinTEPCOandNRAhasbeenestablished.•Managementforsafetyincludestheelementsthattakeintoaccountthesafetyculture.•ConsideringtheperioddurationofthedischargeofALPStreatedwater,thefeedbackofoperatingexperiencefromallinvolvedstructure,systems,andcomponentsincludingtheresultsofsourcetermandenvironmentalmonitoringandtheiranalysisisakeymeansofenhancingsafety.2.4.JustificationFacilitiesandactivitiesthatgiverisetoradiationrisksmustyieldanoverallbenefit.JustificationisafundamentalprinciplefortheinternationalstandardsofRadiationprotection.Itconsidersthatactivitiesgivingrisetoradiationrisksmustyieldanoverallbenefit,namelythatanydecisionthatalterstheradiationexposuresituationshoulddomoregoodthanharm.InaccordancewithGSRPart3[8],“thegovernmentortheregulatorybody,asappropriate,shallensurethatprovisionismadeforthejustificationofanytypeofpracticeandforreviewofthejustification,asnecessary,andshallensurethatonlyjustifiedpracticesareauthorized”.Inparagraph2.11,GSG-8[10]statesthat“Forplannedexposuresituations,justificationistheprocessofdeterminingwhetherapracticeis,overall,beneficial,i.e.whethertheexpectedbenefitstoindividualsandtosocietyfromintroducingorcontinuingthepracticeoutweightheharm(includingradiationdetriment)resultingfromthepractice.Thebenefitsapplytoindividualsandsocietyasawhole,andincludebenefitstotheenvironment.Radiationdetrimentmayonlybeasmallpartofthetotalharm.Justificationthusgoes19farbeyondthescopeofradiationprotection,andalsoinvolvestheconsiderationofeconomic,societalandenvironmentalfactors.”TherequestoftheGovernmentofJapantotheIAEAtoreviewtheapplicationofrelevantinternationalsafetystandardstothedischargeofALPStreatedwaterintotheseawassubmittedaftertheGovernment’sdecisionwasmade.Therefore,thescopeofthecurrentIAEAsafetyreviewdidnotincludeanassessmentofthedetailsofthejustificationprocessfollowedbytheGovernmentofJapan.However,theIAEAnotesthatbasedonthehistoricaldetailsmadepublicbytheGovernmentofJapan(seePart1),andtheinvolvementoftheIAEAinotherdecommissioningworkatFDNPS,adecision-makingprocesswasfollowedbytheGovernmentofJapanandwhichjustifiedthefinalchoiceofhowtomanagetheALPStreatedwaterstoredatFDNPS.Additionally,throughouttheIAEA’sreview,itwasacknowledgedthattheTEPCO’sapplicationbasedontheapproachidentifiedbytheGovernmentofJapanwasreviewedandapprovedbytheregulatorybody,NRA.TheGovernmentofJapanhasthefinaldecision-makingauthoritytodeterminehowtohandlethetreatedwater,andhowthatdecisionisjustified.Notwithstanding,thejustificationofthefinalchoiceofhowtomanagetheALPStreatedwaterstoredatFDNPSisextremelyrelevantformanystakeholdersandmeritsaclearexplanationfromtheGovernmentofJapan.ThisexplanationisprovidedintheBasicPolicypublishedbytheGovernmentofJapaninApril2021andthroughfurtherexplanationsandclarificationsprovidedtointerestedparties.ThroughouttheIAEA’sreview,theTaskForcefrequentlyhighlightedtheimportanceofclear,frequent,andrelevantcommunicationwithinterestedpartiesabouttheplanneddischarge.Itisimportanttomentionthatthejustificationdecisiongoesfarbeyondthescopeofradiationprotection,andalsoinvolvesotherconsiderations,manyofwhicharenottechnicalinnature,suchaseconomicandsocietalfactorsandthereforeitisnotfortheIAEAtocommentonandanalysethenon-technicalaspectsofthisdecision.TheIAEAalsonotesthatwhereexpectedexposuresarelow,factorsotherthanradiationsafety(e.g.,economic,societal)maybecomemoreimportantandcandrivethedecision-makingprocess.Furthermore,GSG-9[9]statesthat“Justificationappliestotheoverallpracticeandnottoindividualaspectsofthepractice...”Therefore,itisclearthattheissueofjustificationofthedischargeofALPStreatedwaterisinherentlylinkedwiththeoveralljustificationofthedecommissioningactivitiestakingplaceattheFDNPSandthusisinfluencedbybroaderandmorecomplexconsiderations.Decisionsregardingjustificationshouldbetakenatasufficientlyhighgovernmentalleveltoenablealltheconsiderationsthatmayberelatedtothebenefitsanddetrimentstobetakenintoaccount.Asnuclearsafetyisanationalresponsibility,itisadecisionfortheGovernmentofJapantotake.Conclusions•TheresponsibilityforjustifyingthedecisiontodischargetheALPStreatedwaterfallstotheGovernmentofJapan.•TheIAEAnotesthattheGovernmentofJapanhasfollowedadecision-makingprocessleadingtothejustificationofitsapproach.202.5.OptimizationofProtectionProtectionmustbeoptimizedtoprovidethehighestlevelofsafetythatcanreasonablybeachieved.Afundamentalprincipleoftheinternationalsafetystandardsisthattheprotectionagainstexposuretoionizingradiationmustbeoptimizedtoprovidethehighestlevelofsafetythatcanreasonablybeachievedtakingintoaccountrelevanteconomic,social,andotherfactors.SafetymeasuresthatareappliedtothedischargeoftheALPStreatedwaterneedtobeoptimizedtoprovidethehighestlevelofsafetythatcanreasonablybeachievedthroughoutthelifetimeoftheactivity.Variousfactorsinfluencingoptimizationofprotection,include:thenumberofpeople(workersandthepublic)whomaybeexposedtoradiation;thelikelihoodoftheirincurringexposures;themagnitudeanddistributionofradiationdosesreceived;radiationrisksarisingfromforeseeableevents;andeconomic,socialandenvironmentalfactors.TheTaskForcediscussedwiththeGovernmentofJapantheimportanceoftherequirementonoptimizationofprotection,includedintherelevantinternationalsafetystandards,intheJapaneseregulatoryframework.TheTaskForcenotedthattheBasicPolicyonHandlingofALPSTreatedWaterattheTokyoElectricPowerCompanyHoldings’FukushimaDaiichiNuclearPowerStationnotesthat“…[the]dischargeofALPStreatedwaterintotheseawillbeimplementedatFDNPS,onthepremisetomakebesteffortstominimizetherisksbytakingmeasuressuchaspurificationanddilutionbasedontheALARAprinciple,understrictcontrol.”ALARAwhichstandsfor“aslowasreasonablyachievable”referstotheconceptofmakingeveryreasonableefforttokeepexposurestoionizingradiationaslowaspracticableconsideringrelevantsocietal,economic,andotherconsiderations.Therelevantinternationalsafetystandardsrequiretheestablishmentofdoseconstraintsaspartoftheprocessforoptimizationofprotectionforanyplannedexposuresituation.ForthedischargeoftheALPStreatedwater,theestablishmentofaprospectiveanddischarge-relatedrestrictionontheindividualdoseattributabletothedischarge,providesabasiclevelofprotectionforthemosthighlyexposedindividualsduetothedischarge,andservesasanupperboundonthedoseintheoptimizationofprotectionforthedischarge.RepresentativePersonTherepresentativepersonisdefinedas“Anindividualreceivingadosethatisrepresentativeofthedosestothemorehighlyexposedindividualsinthepopulation”.Therepresentativepersonwillgenerallybeahypotheticalconstructandnotanactualmemberofthepopulation.Theconceptisusedtodeterminecomplianceorinprospectiveassessments.[10]Inaccordancewithparagraph5.32ofGSG-10[11],thedosetotherepresentativepersonshouldbecalculatedusingcharacteristicsselectedfromagroupofindividualsrepresentativeofthosemorehighlyexposedinthepopulation.GSG-10explainsthatthecharacteristicsoftherepresentativepersonshouldbespecifiedbytheapplicantinaccordancewithnationalregulationsandinagreementwiththeregulatorybody.21NRAselectedadoseconstraintof0.05mSvinayeartotherepresentativepersonforthedischargeofALPStreatedwater.RefertoPart3(Section3.1)foradditionalinformationontherelevantdosecriterionsetbyNRA.Itwassubsequentlyusedintheprocessforoptimizationofprotection,theintendedoutcomeofwhichbeingthatallexposuresarecontrolledtolevelsthatareaslowasreasonablyachievable,takingintoaccounteconomic,societalandenvironmentalfactors.TheselecteddoseconstraintisappliedtothepublicexposureattributabletothedischargeoftheALPStreatedwater.Itservesasaboundaryconditionindefiningtherangeofoptionsforthepurposeofoptimizationofprotection.TheIAEAnotesthatdoseconstraintsarenotdoselimits(seefundamentalsafetyprinciple6:limitationofrisktoindividuals)intheinternationalsafetystandards:exceedingadoseconstraintdoesnotrepresentnon-compliancewithregulatoryrequirements,butitcouldresultinfollow-upactions.TEPCOcarriedoutaradiologicalenvironmentalimpactassessment(REIA)toestimatethedosetotherepresentativepersonresultingfromthedischargesofALPStreatedwaterandtoevaluatethecompliancewiththedoseconstraintof0.05mSvinayear.TheprocesscarriedoutbyTEPCOfortheelaborationoftheREIAisconsistentwithrelevantinternationalsafetystandards.FurtherdetailedinformationregardingtheREIAcanbefoundinPart3(Section3.4).DoseSeveraldifferenttermsexistrelatingtothemeasurementandreportingof“radiationdose”.Doseisde-finedas“Ameasureoftheenergydepositedbyradiationinatarget.”Thisconceptisusedwhenconsid-eringhowionizingradiationimpactspeople.Therearemanydifferentdoseconceptsthatareimportanttounderstandsuchas:•Absorbeddoseisthefundamentaldosimetricquantity.Itisthetotalenergydepositedbyioniz-ingradiationinagivenvolumeoftissuedividedbythemassofthattissue.TheunitofabsorbeddoseisjoulesperkilogramandgiventhenameGray(Gy).•Effectivedoseistheabsorbeddosemultipliedbyaradiationweightingfactor(wR)forthetypeofradiationandatissueweightingfactor(wT)thatreflectstherelativesensitivitiesoforgansandtissues.TheunitofeffectivedoseistheSievert(Sv).•Committedeffectivedoseisthesumoftheeffectivedosefromexternalexposureandtheeffec-tivedosefromintakesofradionuclides(i.e.,frominternalexposurebyingestionandinhalation.Forthepurposesofcalculatingthedosefromintakesofradionuclidesintothebody,anadultisassumedtobeage20,atthetimeofintakeandthedosecalculatedistheradiationdosetothebodyoverape-riodof50years(i.e.,acommitteddosetoage70).Childrenareassumedtobeage10andinfantsareassumedtobeage1atthetimeofintake;thecommittedradiationdosetothebodybeingcalculatedfor60yearsand69years,respectively(i.e.,toage70).ThecommittedeffectivedoseisthecalculateddoseintheREIA.Sincetheassessmentwasconductedbasedonconservativeassumptions,thereisnosignificantriskofunderestimation.AnypersonlivinginthewiderareawouldbefarlessaffectedbyexposurethantherepresentativepersonidentifiedintheREIA.TheREIA[15]providesanestimateofthecommittedeffectivedosetotherepresentativeperson(foradult,childandaninfant),rangingfrom0.000002(2E-06)to0.00004(4E-05)mSv/year.Theresultsweremuch22smallerthanthedoseconstraintof0.05mSvperyear.Furthermore,theresultsaresignificantlybelowtheaccepted0.01mSvthresholdbelowwhichitisusuallynotrecommendedtoconductoptimization.TheseresultsarelargelyduetothelimitssetbytheGovernmentofJapanforthedischargeofALPStreatedwaterbothintermsoftritiumconcentrationandannualdischargelimitfortritium.Inordertominimizetheimpactonthesurroundingenvironmentandthereputationaldamage,Japanhassetamaximumtritiumconcentration(1,500Bq/L)forthedischargeandatotalannualtritiumdischargelimit(22TBqperyear).TheIAEAunderstandsthatdischargelimitssetingovernmentpolicywereinfluencedbyawiderangeofprevailingcircumstances,suchassocietalconcernsandadesiretoreducetheoverallradioactivitybeingreleasedtotheenvironment.TheTaskForceacknowledgesthatthesecouldbeconsideredaskeyfactorsthatinformedtheoptimizationprocess.Conclusions•TheNRAestablishedrequirementsfortheoptimizationofprotectionandsubsequentlyenforcedthem.•TEPCOhasensuredthattheoptimizationofprotectionandsafetyhasbeenconsidered,takingintoaccounttheprevailingcircumstances.•IAEAconsidersthatifthereisanydecisiontochangeparametersrelatedtothedischargeinthefuture,furtherstudieslookingattheoptimizationofprotectionshouldbeconductedandevaluated.DoseConstraintsAdoseconstraintshouldbeexpressedintermsoftheannualeffectivedoseandisestablishedforeachsource–eachplannedoperationoractivity,includingtheauthorizeddischargeofradioactivity–thatmaycontributetotheexposureofthepublic.AsstatedinParagraph5.15ofGSG-9[9],“Thedoseconstraintforeachparticularsourceisintended,amongotherthings,toensurethatthesumofdosesfromplannedoperationsofthatsourceandofalltheauthorizedsourcesthatmaycontributetotheexposureofthepublicremainswithinthedoselimit”,whichis1mSvperyearasstatedinGSRPart3[8].Adoseconstraintshouldalsobehigherthanadoseoftheorderof0.1mSvinayear.Therefore,inpracticalterms,doseconstraintsshouldbeselectedwithintherangeof0.1tolessthan1mSvinayear,takingintoaccountthecharacteristicsofthesiteandofthefacilityoractivity,thescenariosforexposureandtheviewsofinterestedparties.Doseconstraintsserveasboundaryconditionswhendefiningoptionsforprotectingpeopleandtheen-vironmentfromtheharmfuleffectsofionisingradiation.Assuch,doseconstraintsarethestartingpointforoptimizationofprotectionandsafety.Afterexposureshaveoccurred,thedoseconstraintmaybeusedasabenchmarkforassessingthesuitabilityofthestrategyforprotectionandsafety(referredtoastheprotectionstrategy)thathasbeenimplementedandforadjustingthestrategyasnecessary.232.6.LimitationofRiskstoIndividualsMeasuresforcontrollingradiationrisksmustensurethatnoindividualbearsanunacceptableriskofharm.Thisfundamentalsafetyprinciplerequiresthatmeasuresforcontrollingradiationrisksmustensurenoindividualbearsanunacceptableriskofharm.Theprinciplesofjustificationandoptimizationarefundamentaltoenhancingradiationprotection.Butjustificationandoptimizationofprotectiondonotinthemselvesguaranteethatnoindividualbearsanunacceptableriskofharm.Consequently,dosesandradiationrisksmustbecontrolledwithinspecifiedlimitsthatrepresentthejudgementoftheregulatorybody(orotherGovernmentauthorities)astowhatconstitutesanacceptablerisk.Thisfundamentalsafetyprincipleisimplemented,inpractice,usingdoselimitswhichrepresentalegalupperboundofacceptabilityfortherelevantapprovingauthority.ICRPhasrecommendeddoselimits,andtheseareincorporatedintotherelevantinternationalsafetystandards.TheNRAestablisheddoselimitsforpublicexposuretobeappliedbyTEPCOwhichareconsistentwithwhatisincludedintheinternationalsafetystandardsandrecommendedbyICRP.Thesedoselimitsapplytothesumoftherelevantdosesfromexternalexposureinayearandtherelevantcommitteddosesfromintakesinayear;theperiodforcalculatingthecommitteddoseforadultsshallnormallybe50yearsfromintakeandshallbeupto69yearsforintakesbyinfants(i.e.,uptoage70).Asnotedunderfundamentalsafetyprinciple5,OptimizationofProtection,TEPCOcarriedoutaradiologicalenvironmentalimpactassessment(REIA)toestimatethedosetothepublicduetothedischargesresultingfromALPStreatedwater.TheprocesscarriedoutbyTEPCOfortheelaborationoftheREIAisinlinewiththeinternationalsafetystandards.TheREIAconsideredthecharacterizationofthesourceofradiationasitrelatestopublicexposure,thedispersion,andthetransferofradionuclidesintheenvironmentforidentifiedexposurepathwaysandtheexternalexposureandinternalirradiation.TheREIAprovidesanestimateofthecommittedeffectivedosetotherepresentativeperson(foradult,childandaninfant),rangingfrom0.000002(2E-06)to0.00004(4E-05)mSv/year.Theresultswerewellbelowthedoselimitof1mSv/yearforthegeneralpublicandthedoseconstraintof0.05mSv/year.PotentialExposureThedefinitionof“potentialexposure”intheinternationalsafetystandardsis“Prospectivelyconsideredexposurethatisnotexpectedtobedeliveredwithcertaintybutthatmayresultfromananticipatedoperationaloccurrenceoraccidentatasourceorowingtoaneventorsequenceofeventsofaprobabilisticnature,includingequipmentfailuresandoperatingerrors.”Aspartofthesafetyassessmentrequiredtobecarriedoutforfacilitiesandactivities,varioustypesofaccidentarepostulatedinordertoidentifyengineeredsafetyfeaturesandoperationalactionstoreducetheirlikelihoodand,ifanaccidentdoesoccur,tomitigateitsconsequences.Thisanalysisdeterminesifadequatedefenceindepthhasbeenachievedandgivesinsightsintotheprobabilityofvariousaccidentscenarios,takingintoaccountthesafetymeasuresinplaceandtheireffectiveness.Thepotentialexposuresofmembersofthepublicareassessedusingtheseaccidentscenarios.[11]WithintheREIA,theassessmentofpotentialexposureshasbeenmadeandestimatesofdosetomembersofthepublicresultingfrompostulatedaccidentscenariosidentifiedthroughthesafetyassessment24estimated.Thepotentialexposurescenariosincludethecharacteristicsoftheeventsorsequencesofeventsthatmayleadtoanyunintendedexposure.Theassociatedsourceterm,themodellingofdirectirradiation,thedispersionandtransferofradionuclidesintheenvironment,identificationoftherelevantexposurepathwaystotherepresentativepersonforpotentialexposuresandtheassessmentofthedosetotherepresentativepersonwereconsidered.Theenvironmentaldispersionandtransferareestimatedwithrelevantmodels,consideringthedefinedenvironmentalconditions,onthebasisofmeteorologicalandoceanographicdata.Basedontheabove,TEPCOassessedthepotentialexposuresofmembersofthepublicinitsREIA,assumingtwoaccidentscenarios:onewhereabout10,000m3ofundilutedtreatedwaterleaksfrom1tankgroupintotheseaaccidentallyover20days,andonewhereabout30,000m3ofundilutedtreatedwaterisaccidentallydischargedoveronedayfrom3tankgroups.Thedosecalculatedfortheadultrepresentativepersonisintherangeof0.0002(2E-04)mSvto0.01(1E-02)mSvforthe2accidentscenariosconsidered.Inbothscenarios,TEPCOconservativelyassessedallexposurepathways,andconfirmedthattheexposureoftherepresentativepersonlivingnearthepowerplantwouldbewellbelow5mSvperevent,whichistheestablishedintheinternationalsafetystandardsintheeventofanaccident.ResultsandVerificationofCompliancewiththeinternationalsafetystandardsRadiologicalImpactAssessmentInternationalSafetyStandardsCriteriaAssessmentresultsforrepresentativeperson(adult)duetodischargeofALPStreatedwaterRadiologicalimpactonhu-mansinnormaloperationsDoselimitforpublic1mSv/year0.000002-0.00003mSv/yearRadiologicalimpactincaseofpotentialexposureTypically5mSv/event0.0002to0.01mSv/eventConclusions•Theresultsoftheimpactofthedischargetreatedwateronhumansareconsistentwiththeinternationalsafetystandards.•Theradiologicalimpactassessmentofthedischargeintotheseaonhumansinnormaloperationandincaseofpotentialexposuresisbelowthedoseconstraintsandthedoselimitformembersofthepublicestablishedattheinternationalsafetystandards.•Allassumptionsfortheselectedpotentialexposurecasesareconservative.252.7.ProtectionofPresentandFutureGenerationsandtheirEnvironmentPeopleandtheenvironment,presentandfuture,mustbeprotectedagainstradiationrisks.Theprotectionoffuturegenerationsandtheenvironmentisanimportantconceptthatis,embeddedintheconceptsofjustification,optimizationandthelimitationofrisktotheindividual.Nonetheless,itispresentedseparatelyintheinternationalsafetystandards.Thisfundamentalsafetyprinciplesimplyrequiresthatpeopleandtheenvironment,presentandfuture,mustbeprotectedagainstradiationrisks.Aspartofitsactivities,theGovernmentofJapanandTEPCOmusttakeintoaccountthatradiationrisksattributabletothedischargemighttranscendnationalbordersandmaypersistforlongperiodsoftime.Thus,themeasurestocontrolthedischargesconsideranypossibleconsequence,nowandinthefuture.Inparticular,itisimportanttonotethattheinternationalsafetystandardsapplynotonlytolocalpopulationsbutalsotopopulationsremotefromthedischargeactivities;andthatwhereeffectscouldspangenerations,subsequentgenerationshavetobeadequatelyprotectedwithoutanyneedforthemtotakesignificantprotectiveactions.Thisisanimportantfundamentalsafetyprinciplegiventhelong-termapproachcurrentlyenvisagedfordischargingALPStreatedwateratFDNPS.ThroughitsworktheIAEAhasnotedthattheREIAproducedbyTEPCOandreviewedbyNRAhasdemonstratedthatthedosetorepresentativepersonsinneighbouringcountrieswillbeundetectableandnegligible.Inordertoensuretheproperprotectionoffuturegeneration,theTaskForcedecidedtocorroboratethatthedosecommitment,ratherthanthedoseincurred,isthefundamentalquantityfordeterminingcompliancewiththeinternationalsafetystandards.Thefundamentalquantityforassessingdosesshallbethedoseduetoexternalexposureinayearplusthecommitteddosefromintakesofradionuclidesinthatyear.Thismeansthatthetotalannualdosecalculatedisthatreceivedoveralifetime(assumedtobeuntiltheageof70)fromintakesofradionuclidesduetotheALPStreatedwaterthatisdischargedtotheseainanassignedyear.Itshouldbenotedthatthetotalamountoftritium,14Cand129ItobereleasedeachyearinthedischargeofALPStreatedwaterwillbewellbelowtheamountoftheseradionuclidesproducedbynaturalprocesseseachyear,suchasinteractionofcosmicrayswithgasesintheupperatmosphere.Productionof3H,14Cand129IbynaturalprocessesTherearethreemainsourcesofnaturaltritiumonearth:productionintheatmospherebycosmicrays;productionintheatmospherebyenergeticparticlesoriginatedfromsolarcoronalmassejections;anddirectaccretionfromthesun.TritiumproducedbynaturalprocessesonearthisrapidlyconvertedintoHTO,whichthenenterstheglobalhydrologicalcycle.Theannualproductionoftritiumduetonaturalpro-cessesisestimatedtobearound280grams,withannualproductionvaryingbetween220to330gramsduetothevariationintheintensityofcosmicduetothesolarcyclevariations.Theaveragevalueof280gramsinayearcorrespondstotheactivityintheorderof100PBq(100,000TBq)inayear.Theglobalinventoryoftritiumisestimatedtobeabout2,000PBq(2,000,000TBq).Thelimitontheamountoftritiuminthetreatedwatertobereleasedeachyearis22TBq.Thisisabout5,00026timeslowerthantheannualproductionontheplanetduetonaturalprocesses,andmuchlessthanthevariationfromyeartoyearintheannualproduction.ThetritiumnaturalbackgroundlevelinthePacificOceanisintherangeof0.1-1Bq/L.Theoceandisper-sionmodellingconductedbyTEPCOindicatesthatconcentrationsoftritiumabovenaturalbackgroundconcentrationswillbelimitedtowithin3kmofthedischargepointatFDNPS.Theconcentrationismuchlowerthanthenaturalbackgroundlevelattheboundaryofthemodelsimulationrange(490kmx270km),themaximumvaluebeing0.00026Bq/L,whichisthreetofourordersofmagnitudelowerthanthenaturalbackgroundlevel.Themainsourceofnatural14Conearthistheproductionintheatmospherebycosmicraysbythenucle-arreaction:14N(n,p)14C.Theglobalinventoryduetonaturalprocessesof14Cisestimatedtobearound1PBq(1,000TBq).Theamountof14CintheALPStreatedwatertobereleasedeachyearisabout2GBq(0.002TBq),whichisabout500,000timeslowerthantheglobalinventoryduetonaturalprocesses.Iodine-129isproducedbythefollowingnaturalprocesses:reactionsofcosmicrayswithxenonintheupperatmosphere;spontaneousfissionof238U;thermalneutroninducedfissionof235U;andneutronactivationreactions128Te(n,γ)129Iand130Te(n,2n)129I..Itisestimatedthattheglobalinventoryof129Iduetonaturalprocessesinthehydrosphere(primarilyoceans)isabout1TBq.Theamountof129Itobereleasedinthetreatedwatereachyearis30-300MBq.Thisisabout3,000-30,000timeslowerthanthesteadystateinventoryofnaturallyoccurring129Iinalloftheoceans.TheTaskForcehasalsoconsideredthatwhereastheeffectsofradiationexposureonhumanhealtharerelativelywellunderstood,albeitwithuncertainties,theeffectsofradiationontheenvironmentareundercontinuousinvestigationbyscience.Thesystemofradiationprotectionestablishedbytheinternationalsafetystandardsprovidesappropriateprotectionofecosystemsinthehumanenvironmentagainstharmfuleffectsofradiationexposure.Thegeneralintentofthemeasurestakenforthepurposesofenvironmentalprotectionhasbeentoprotectecosystemsagainstradiationexposurethatwouldhaveadverseconsequencesforpopulationsofaspecies,ratherthanfocusingonindividualorganisms.ProtectionoftheEnvironmentTheenvironmentisdefinedintheinternationalsafetystandardsas“Theconditionsunderwhichpeople,animalsandplantsliveordevelopandwhichsustainsalllifeanddevelopment,especiallysuchcondi-tionsasaffectedbyhumanactivities”Protectionoftheenvironmentisdefinedisdefinedas“Protectionandconservationofnon-humanspecies,bothanimalandplant,andtheirbiodiversity;environmentalgoodsandservices,suchastheproductionoffoodandfeed;resourcesusedinagriculture,forestry,fisheriesandtourism;amenitiesusedinspiritual,culturalandrecreationalactivities;media,suchassoil,waterandair;andnaturalprocesses,suchascarbon,nitrogenandwatercycles.Thehigh-levelaimoftheprotectionoftheenvironmentsetbytheICRPistoprovideforthemaintenanceofbiologicaldiversityandtoensuretheconservationofspeciesandthehealthofnaturalhabitats,communities,andecosystems.Theradiationrisktopopulationsoffloraandfaunaareexpectedtobenegligible.Themethodsusedfortheassessmentoftheimpactonfloraandfaunaarebasedonthecurrentscientificknowledgeofradiationeffects.TheIAEAinternationalsafetystandardsareinagreementwiththeinternationalenvironmentalprotectionobjectivesofmaintainingbiologicaldiversity,ensuringtheconservationofspecies,andprotectingthehealthandstatusofnaturalhabitats,communities,andecosystems.27TEPCOfollowedamethodologyforassessingtheimpactonfloraandfaunaprovidedintheinternationalsafetystandardsthatisinlinewiththeICRPapproachfortheprotectionofdifferentecosystemsintheenvironment.Consistentwiththisapproach,threespeciesareusedasreferencesfortheprotectionofthemarineenvironment.Theconceptualapproachisthat,ifthecriteriaforthosethreereferencespeciesisnotexceeded,thenallthespeciescanbeassumedtobeequallywellprotected,attheleveloftheirpopulations(particularlyforplannedexposuresituation).Thethreereferencespeciesare:•Flatfish(Left-eyedandright-eyedflounderswidelyinhabittheseaareaaroundtheFDNPS)•Crabs(OvalipespunctatusandPortunustrituberculatuswidelyinhabittheseaareaaroundtheFDNPS)•Brownseaweeds(SargassumandEiseniabicycliswidelyinhabittheseaareaaroundtheFDNPS)TheseplantsandanimalsarewidelydistributedintheseaareaaroundtheFDNPS,sotheradioactivematerialconcentrationintheseawaterusedfortheassessmentisforareferenceareaaroundthedischargepointwherethehighestenvironmentalactivityconcentrationstypicallyoccurlinewiththegenericmethodologyintheinternationalsafetystandards.ForfurtherdetailsrefertoPart3(Section3.4).Inaddition,intheassessmentofdoseratestoplantsandanimals,externalexposureiscalculatedfromradionuclidesseabedsediments,aswellasthosesuspendedintheseawater,totakeaccountoffishthatliveontheseabed(referenceflatfish).TheexposureresultsareforFlatfish0.0000007(0.7E-06)mGyperday,forCrab0.0000007(0.7E-06)mGyperdayandforBrownseaweedof0.0000008(0.8E-06)mGyperday.ThesevaluesarewellbelowtheDerivedConsiderationReferenceLevel(DCRL)providedasanexampleintheinternationalsafetystandardsandestablishedbyICRP.RadiologicalImpactAssessmentonanimalsandplantsintheseaInternationalSafetyStandardsAssessmentresultsFlatfishCrabBrownseaweed1-10mGy/day10-100mGy/day1-10mGy/day0.7x10-6mGy/day0.7x10-6mGy/day0.8x10-6mGy/dayWhiletheTaskForceisawarethatthebehaviourofradioactivesubstancesintheenvironmentiscomplex,itholdstheviewthattherequirementsoftheinternationalstandardsonenvironmentalprotectionhavebeenrespectedandthatradiationexposuretothebiotaattributabletothedischargewillnotbeexpectedtobeanoteworthyconsiderationinmeetingtheseobjectives.TheTaskForcealsounderlineitsconcurrencewiththeinternationalconsensus,expressedinICRPrecommendations,thatthestandardsofcontrolofdischarges(plannedexposures)neededtoprotectthegeneralpublic,whicharebeingfullyappliedtothedischarges,wouldgenerallyensurethatotherspeciesarenotputatrisk.TheIAEAisconfidentthattheinternationalenvironmentalprotectionsobjectiveswillbeamplymetbythecontrolsinplaceforthedischargeofALPStreatedwaterandthatthedoseratestobiotaarenegligiblecomparedtotheinternationalsafetycriteriasetbyICRP.Insummary,thedischargeofthewatermustbemanagedtoprotectfuturegenerationsandtheirenvironmentsinsuchawayastoavoidimposinganundueoruncontrolledburdenonfuturegenerations.TEPCOmustapplysafe,practicable,andenvironmentallyacceptablesolutionsforitslong-termmanagementofALPStreatedwater.TheIAEAnotesthattheexistingassessmentandcontrolsconductedfortheplanneddischargeofALPStreatedwaterfromFDNPSappeartosatisfythisprinciple.28Conclusions•TEPCOhascarriedoutaREIAforthedischargeoftheALPStreatedwater,inlinewiththeinternationalsafetystandards.•Anassessmentoftheradiationdosetothepublicconsideringallsituations,andanassessmentoftheradiationdoseratestomarineanimalsandplantsinnormaloperationwascarriedout.•ItalsohasbeenconfirmedthattheevaluationresultofradiologicalimpactonanimalsandplantsintheseabythedischargeofALPStreatedwaterundernormaloperationsisnegligible.•Theresultsoftheradiologicalenvironmentalimpactassessmentshowthattheestimateddosetopopulationsinneighbouringcountrieswillbenegligible.•TEPCO’smarinedispersionmodelspredictveryinsignificantconcentrationsoftritiumandotherradionuclidesthatwillbeundetectableorindistinguishablefrombackgroundlevelsattheboundaryofthemodellingsimulationarea.DerivedConsiderationReferenceLevelTheICRPhasdefinedcriteriaforassessingandmanagingtheradiologicalimpactonanimalsandplantsintheformof“derivedconsiderationreferencelevels”[12].Derivedconsiderationreferencelevelsspanoneorderofmagnitude;fordoseratesbelowthelowerboundofthebands,noeffectshavebeenob-servedornoinformationoneffectsisavailable.Derivedconsiderationreferencelevelsdonotrepresentlimits;rather,inaccordancewithICRPrecommendations[12]theyshouldbeconsideredaspointsofreferenceforinformingtheappropriatelevelofeffortthatshouldbeexpendedonenvironmentalprotection,dependentontheoverallmanagementobjectives,theactualfloraandfaunapresent,andthenumberofindividualsexposed[12,13].2.8.PreventionofAccidentsAllpracticaleffortsmustbemadetopreventandmitigatenuclearorradiationaccidents.Thisfundamentalsafetyprinciplereferstotheapplicationofgoodengineeringpracticesandpracticablemeasurestopreventaccidentsandtomitigatetheconsequencesofthoseaccidentsthatdooccur.Inparticular,thesiting,location,installationdesign,construction,commissioning,operation,maintenance,orclosureofthefacilityshouldbebasedongoodengineeringpracticetakingintoaccountinternationalandnationalstandards.Theseactivitiesalsoneedtobesupportedbymanagerialandorganizationalfeaturestoensureprotectionandsafetythroughoutthelifetimeofthefacility,safetymarginsinthedesignandconstructionandtakeaccountofthenecessaryquality,redundancy,andcapabilityforinspection,withemphasisonpreventingaccidents,mitigatingtheconsequencesofthoseaccidentsthatdooccurandrestrictinganypossiblefutureexposures.Therefore,itisnecessarytoensurethatamultilevel(defenceindepth)systemofsequential,independentprovisionsforprotectionandsafetythatiscommensuratewiththelikelihoodandmagnitudeofpotentialexposuresisapplied.Inthisregard,theconceptofa“gradedapproach”shouldbeappliedbytheoperator29andregulatorybodytoensurethatthemeasuresappliedtoprotectagainstanypotentialaccidentsareclearlyinlinewiththepotentialforharmtomembersofthepublic.Initsanalysis,theworst-casescenarioidentifiedbyTEPCO,requiringcontrolsformitigation,wastheunintendedreleasedofALPStreatedwaterfromthesite.Theimpactsfromthisunintendedrelease,whicharenegligible,arefurtherdiscussedinfundamentalsafetyprinciple6andPart3(Section3.4).FortheIAEA’ssafetyreview,thevariousengineeredcontrols,facilities,procedures,andothersafetyfeatureswereconsideredbytheTaskForce,anditwasnotedthatthesystemsandprocessesinplacetocontrolthedischargesofALPStreatedwaterareappropriateforthisapplication.TheinclusionsofengineeredcontrolstoensurethatunintendeddischargesofALPStreatedwaterdon’toccur,andtheprocessesandmeasurementstepsinplacetoensurethatthedischargedwaterisappropriatelydilutedtomeettheregulatoryrequirements,allensurethatsufficientcontrolisinplacetoprotectagainstandmitigatetheeffectsfromaccidents.Part3(Section3.2)ofthisreportincludesfurtherinformationabouthowthesystemsandprocessesforsafetywereassessed.Inaddition,theTaskForcenotedtheimportanceofcompliancewiththemaintenanceplan,inspectionprogrammes,andtestingplannedbeforeandduringthedischargeoftheALPS-treatedwater.Conclusions•SoundengineeringdesignandproceduralcontrolsforsafetywereappliedbyTEPCOtocontroltheprocessandtoavoidtheunintentionaldischargeofALPStreatedwater.•Redundancywasbuiltintothesystemforsomecomponents,suchasemergencyisolationvalvesanddetectors,ensuringtheconceptof“defence-in-depth”wasincorporated.2.9.EmergencyPreparednessandResponseArrangementsmustbemadeforemergencypreparednessandresponsefornuclearorradiationincidents.Thegoalofemergencypreparednessistoensurethatanadequatecapabilityisinplacewithintheoperatingorganizationandatlocal,regionalandnationallevelsand,whereappropriate,attheinternationallevel,foraneffectiveresponseinanuclearorradiologicalemergency.Thiscapabilityrelatestoanintegratedsetofinfrastructuralelementsthatincludebutarenotlimitedto:authorityandresponsibilities;organizationandstaffing;coordination;plansandprocedures;tools,equipmentandfacilities;training,drillsandexercises;andamanagementsystem.Inmeetingthisprinciple,itshouldbenotedthattheGovernmentofJapanisacontractingpartyoftheConventiononEarlyNotificationofaNuclearAccident.AccordingwiththeAtomicEnergyBasicAct,aNuclearEmergencyPreparednessCouncilwasestablishedwithintheCabinet,withthePrimeMinisterservingastheChairpersonandtheChiefCabinetSecretary,theMinisteroftheEnvironment,otherMinister(s)ofStateappointedbythePrimeMinister,andtheNRA(NuclearRegulationAuthority)ChairmanservingasViceChairpersons.TheNuclearEmergencyActincludesallmeasurestopreventnucleardisastersandstrengthenedthefunctionsoftheNuclearEmergency30ResponseHeadquartersinanyemergency.TheNRAformulatesspecializedandtechnicalguidelinestoimplementemergencypreparednessmeasures,emergencyresponseandtherestorationfromemergency.TheNRAEPRGuidewasformulated,andtheEmergencyPlanningZone,theEmergencyActionLevel(EAL),theOperationalInterventionLevel(OIL)andothersuchmatterswereestablished.Offsiteresponsemeasures,includethedivisionofrolesbetweenthenationalandlocalgovernments,theemergencyradiationmonitoringsystemandthemedicaltreatmentsysteminanucleardisaster.On-site,appropriatealarmsystemsandequipmentforcommunicationareprovidedsothatproperdirectionsmaybeprovidedtoeveryoneintheSpecifiedNuclearFacilityincaseofanaccident.EquipmentforcommunicationbetweentheSpecifiedNuclearFacilityandoff-sitelocationsisalsoprovided,withredundancyanddiversityofsystemsconsideredintheimplementationofthesemeasures.ThesafetyassessmentcarriedoutbyTEPCOfortheALPStreatedwaterprojecthasidentifiedpossibleabnormaleventsandexternalevents.TwoeventsthatcouldleadtoanuncontrolledreleaseoftheALPStreatedwaterfromthemeasurementandconfirmationtankswereconsidered.Forthescenariogivingrisetothehighestdosesofthetwoscenarios(accidentaldischargetoseaofabout30,000m3ofundilutedtreatedwaterfromthetanksinoneday),thepotentialexposurecalculatedfortheadultrepresentativepersonis0.0002(2E-04)mSvto0.01(1E-02)mSv.Thisdemonstratesthattheradiationrisksfromsuchaneventarenegligibleandfarbelowwhatissuggestedininternationalsafetystandards.WhilethedischargeofALPStreatedwaterfallsunderthebroaderemergencyandresponseprovisionsfortheFDNPS,nospecificmeasuresbeyondthecontrolsputinplaceasdiscussedinPart3areenvisaged.Conclusions•JapanhasanintegratedandcoordinatedemergencysystemforpreparednessandresponseforanyradiologicalemergencyaspartofthenationalemergencysystemincludingthedecommissioningofFDNPS.•Theemergencypreparednessandresponsearrangementsincludingtherolesandresponsibilitiesareinplaceforaneffectiveresponseatthesceneand,asappropriate,atthelocal,regional,nationalandinternationallevels.•ForthepotentialincidentsandeventsassociatedwiththedischargeofALPStreatedwaterthathavebeenconsidered,radiationriskswouldbeinsignificantandwouldnotnecessitateresponsemeasures.•IngeneralthelegalframeworkisinplaceforEPRandtheFDNPScomplieswiththoserequirements.•WithregardtoALPStreatedwaterdischarge,noradiologicalemergencyisanticipated.312.10.ProtectiveActionstoReduceExistingRadiationRisksProtectiveactionstoreduceexistingorunregulatedradiationrisksmustbejustifiedandoptimized.Thelastfundamentalsafetyprinciplereferstoprotectiveactionstoreduceexistingorunregulatedradiationrisks.TheIAEAsafetyfundamentalsprinciplespublicationprovidesexamplesofsituationswherethefundamentalsafetyprincipleforexistingexposuresituationswouldbeapplicable.Theseinclude:(i)thosesituationsconcerningradiationexposureofessentiallynaturalorigin,forexample,exposureduetoradonindwellings,(ii)thosesituationsconcerningextantexposuresituationsthatarisesfromhumanactivitiesconductedinthepastthatwereneversubjecttoregulatorycontrol,orthatweresubjecttoanon-rigorousregimeofcontrol;and,(iii)thosefollowingremediationmeasurestakenfollowinganuncontrolledreleaseofradionuclidestotheenvironment.ThedischargeoftheALPStreatedwaterdoesnotfallintoanyofthesesituations.TheradiationriskthatmightbeattributedtothedischargeofALPStreatedwateraresubjecttoreviewbyNRA,asaplannedexposuresituation.ThissafetyprincipleisthereforenotapplicabletothedischargeofALPStreatedwater.Howeveritisimportanttonotethatotherrelevantinternationalsafetystandardsstillapplyandarecoveredindetailthroughoutthisreport.Conclusions•TheFDNPSismanagedasanexistingexposuresituationintheJapaneseregulatoryframework;howeverthedischargesofALPStreatedwaterintothesea,whicharecontrolleddischarges,areviewedasaplannedexposuresituationbyNRA,consistentwithrelevantinternationalsafetystandards.Therefore,thesedischargesshouldconformtotheinternationalsafetystandardsappliedtoplannedexposuresituationsandthusthisfundamentalsafetyprincipleisnotapplicabletothedischargeofALPStreatedwater.TypesofexposuresituationTheinternationalsafetystandardsdistinguishbetweenthreedifferenttypesofexposuresituation[8]:•Aplannedexposuresituationisasituationofexposurethatarisesfromtheplannedoperationofasourceorfromaplannedactivitythatresultsinanexposureduetoasource.•Anemergencyexposuresituationisasituationofexposurethatarisesasaresultofanaccident,amaliciousactoranyotherunexpectedevent,andrequirespromptactioninordertoavoidortoreduceadverseconsequences.•Anexistingexposuresituationisasituationofexposurethatalreadyexistswhenadecisionontheneedforcontrolneedstobetaken.Existingexposuresituationsincludesituationsofexposuretonaturalbackgroundradiation.3233ASSESSMENTOFCONSISTENCYWITHSAFETYREQUIREMENTS3.1.RegulatoryControlandAuthorization3.1.1BackgroundEstablishingregulatoryframeworkandregulatorybodyTheIAEAinternationalsafetystandardsoutlinetheresponsibilitiesandfunctionsofthegovernment.GSRPart1(Rev.1)[14],establishesrequirementson:theessentialaspectsofthegovernmentalandlegalframework;establishingaregulatorybody;andtakingactionsnecessarytoensuretheeffectiveregulatorycontroloffacilitiesandactivities—existingandnew—utilizedforpeacefulpurposes.Paragraph2.2ofGSRPart1(Rev.1)[14]states:“Thegovernmentestablishesnationalpolicyforsafetybymeansofdifferentinstruments,statutesandlaws.Typically,theregulatorybody,asdesignatedbythegovernment,ischargedwiththeimplementationofpoliciesbymeansofaregulatoryprogrammeandastrategysetforthinitsregulationsorinnationalstandards.Thegovernmentdeterminesthespecificfunctionsoftheregulatorybodyandtheallocationofresponsibilities.Forexample,thegovernmentestablisheslawsandadoptspoliciespertainingtosafety,whereastheregulatorybodydevelopsstrategiesandpromulgatesregulationsinimplementationofsuchlawsandpolicies.Inaddition,thegovernmentestablisheslawsandadoptspoliciesspecifyingtheresponsibilitiesandfunctionsofdifferentgovernmentalentitiesinrespectofsafetyandemergencypreparednessandresponse,whereastheregulatorybodyestablishesasystemtoprovideeffectivecoordination.”GSRPart1(Rev.1)[14]alsoincludesspecificrequirementsfortheregulatorybody,withinthebroadergovernmentinfrastructure.Paragraph4.2ofGSRPart1(Rev.1)[14]statesthat:“Theresponsibilitiesoftheregulatorybodyshallbedischargedwithin,andaredependentupon,thegovernmentalandlegalPART334frameworkforsafety.”Whiletheregulatorybodyoperateswithintheoverallgovernmentalandlegalframeworkforsafety,theimportanceoftheindependentroleoftheregulatorybodyisemphasizedinRequirements3,4and17ofGSRPart1(Rev.1)[14].Forexample,Requirement4ofGSRPart1(Rev.1)[14]statesthat:“Thegovernmentshallensurethattheregulatorybodyiseffectivelyindependentinitssafetyrelateddecisionmakingandthatithasfunctionalseparationfromentitieshavingresponsibilitiesorintereststhatcouldundulyinfluenceitsdecisionmaking.”AuthorizationofdischargesfromafacilityoractivityForfacilitiesoractivitiesthatmightpresentpotentiallyhigherradiationrisks,itmaybeappropriatefortheregulationofdischargesfromsuchfacilitiesoractivitiestobemanagedbymeansofanauthorization(registrationorlicensing,asrelevant)thatestablishesstringenttechnicalandregulatoryconditions,includingfortheadequatemanagementandcontrolofthesedischargesandtheirradiologicalconsequences.GSRPart3[8]establishesrequirementsandGSG-9[9]providesrecommendationsontheregulatorycontrolandauthorizationofdischargesforboththeregulatorybodyandthelicenseeorapplicant.Paragraph5.2ofGSG-9[9]statesthat“theregulatorybodyshouldestablishtheauthorizationprocessforfacilitiesandactivities,includingprovisionsfordischarges,usingtheconceptofagradedapproach,inaccordancewiththeexpectedradiologicalimpactonthepublicandtheenvironment.”Paragraph5.31ofGSG-9[9]states:“Theregulatorybodyshouldestablishtheprocesstobefollowedbyanapplicantseekinganauthorizationfordischargesoncetheneedforanauthorizationfordischargeshasbeenestablished.Thestepsoftheauthorizationprocessmaybeasfollows:a)Theregulatorybodyshouldspecifytherelevantdoseconstraintforthefacilityoractivityunderconsideration(seeparas5.15–5.19andtheAnnex).b)Theapplicantshouldcharacterizethedischargesandthemainexposurepathwaysidentified,inordertoassessadequatelytheexposureoftherepresentativeperson.c)Theapplicantshouldpresentthemeasurestobeusedfortheoptimizationofprotectionandsafetyofthepublic,havinggivenconsiderationtomeasuresforkeepingtheexposuresduetodischargesaslowasreasonablyachievableandhavingtakenintoaccountallrelevantfactors.d)Theapplicantshouldassessthedosestotherepresentativeperson.Thismayinvolveanumberofiterations,startingwithasimple,cautiousgenericassessmentand,ifnecessary,amoredetailed,sitespecificstudy.e)Theapplicantshouldsubmittheresultsoftheassessmenttotheregulatorybody.Theregulatorybodyshouldevaluatewhetherthemodelsandassumptionsusedbytheapplicantareappropriate,shouldcomparetheresultsoftheassessmentwithdoselimitsanddoseconstraints,andshouldevaluatewhethertheassesseddosesareinaccordancewiththeneedtoprovideoptimizedprotectionofthepublic.f)Theregulatorybodyshouldsetthedischargelimitsandshouldestablishconditionsbywhichcomplianceduringoperationistobedemonstrated,includingbymeansofsourcemonitoringandenvironmentalmonitoringsystemsandprogrammes.g)Theregulatorybodyshouldissueanauthorizationfordischargesuponitssatisfactionthatthemodelsandassumptionsarevalidandthatthedoseswillnotbehigherthantheoptimizedlevels.”ThesestepsaresummarisedinafigurewithinGSG-9[9],whichiscopiedbelow(seeFigure3.1.).Figure3.1.alsoshowsthoseresponsibleforeachstepoftheprocess.35Figure.3.1:Stepsinsettingdischargelimits,indicatingthoseresponsible(FIG.3ofGSG-9[9])EstablishingdoseconstraintsHavingconcludedthatthereisaneedforanauthorization,thefirststepoftheauthorizationprocessdescribedinGSG-9[9](andshowninFigure3.1)reflectstherequirementsetoutinParagraph3.120ofGSRPart3[8]that“Thegovernmentortheregulatorybodyshallestablishorapproveconstraintsondoseandconstraintsonrisktobeusedintheoptimizationofprotectionandsafetyformembersofthepublic”.Onceanappropriatedoseconstrainthasbeendeterminedbytheregulator,theapplicantshouldcharacterizethedischargesandthemainexposurescenarios,consideroptimisationofprotectionandassessdosestotherepresentativeperson,asshowninFigure3.1.TheseactionsoftheapplicantaredescribedinmoredetailinPart3(Section3.4),theoutputofwhichisaradiologicalenvironmentalimpactassessment(REIA).Thisisaniterativeprocessthatconsidersoptimizationofprotectionandsafety.EstablishingrequirementforoptimisationofprotectionForsituationsinwhichindividualsareorcouldbesubjecttopublicexposure,Requirement11ofGSRPart3[8]statesthat“Thegovernmentortheregulatorybodyshallestablishandenforcerequirementsfortheoptimizationofprotectionandsafety,andregistrantsandlicenseesshallensurethatprotectionandsafetyisoptimized.”Doseconstraintsarethestartingpointforoptimizationofprotectionandsafety,theintendedoutcomeofwhichbeingthatallexposuresarecontrolledtolevelsthatareaslowasreasonablyachievable(ALARA),economic,societalandenvironmentalfactorsbeingtakenintoaccount.36GSG-8,paragraph3.33[10]statesthat“Optimizationofprotectionandsafetycanbeappliedtothecomponentpartsofaparticularpracticeandcanbelimitedtoconsiderationofthedosestoparticulargroupsofpeople.However,theboundaryconditionsforanyanalysisforthepurposesofoptimizationshouldbecarefullychosensincetheremaybeconsequencesforothercomponentpartsofthepracticeorothergroupsofpeople.Forinstance,thecostsandbenefitsofdifferenteffluenttreatmentoptionsatanuclearpowerplantshouldbeconsideredintheoptimizationofprotectionofthepublicandprotectionoftheenvironmentagainstexposuresduetoradioactivedischargestotheenvironment.Someoftheseoptionsmayhavesignificantimplicationsforthewaysolidwastesarestoredatthefacility,orfortheoccupationalexposureofworkers,whichalsohavetobeconsideredintheoptimizationprocess.”Paragraph5.32ofGSG-9[9]statesthat“Whentheprojecteddosestomembersofthepublicareoftheorderof10μSvperyearorbelow,aprocessforoptimizationshouldnotnormallyberequired,onthebasisthattheeffortsforfurtherdosereductionwouldgenerallynotfulfiltherequirementforoptimization.”EstablishingdischargelimitsThefinalsteppriortoissuinganauthorizationinvolvestheregulatorybodyestablishingdischargelimitsforfacilitiesandactivitiestocontroltheexposurestothepublicandensurethatprotectionofmembersofthepublicisoptimizedfromtheradiationprotectionperspective.AsstatedinParagraph5.43ofGSG-9[9],“Tosetthedischargelimits,prospectiveestimatesofthedosetomembersofthepublicshouldbeusedtodetermineacceptableoptimizeddischargelevelsthatmeettheestablishedradiologicalcriteria”(thedoseconstraint).ThedischargelimitsareusuallysetasBqperyearofeachradionuclidedischarged.Ifthedischargelimitisexpressedasanactivityconcentration,theassociatedvolumeneedstobespecified.Paragraph3.123ofGSRPart3[8]requiresthat“Theregulatorybodyshallestablishorapproveoperationallimitsandconditionsrelatingtopublicexposure,includingauthorizedlimitsfordischarges.Theseoperationallimitsandconditions:a)Shallbeusedbyregistrantsandlicenseesasthecriteriafordemonstrationofcomplianceafterthecommencementofoperationofasource;b)Shallcorrespondtodosesbelowthedoselimitswithaccounttakenoftheresultsofoptimizationofprotectionandsafety;c)Shallreflectgoodpracticeintheoperationofsimilarfacilitiesoractivities;d)Shallallowforoperationalflexibility;e)Shalltakeintoaccounttheresultsoftheprospectiveassessmentforradiologicalenvironmentalimpactsthatisundertakeninaccordancewithrequirementsoftheregulatorybody.”ThesubmissionoftheREIAtotheregulatorybody,discussionoftheresultsandreviewbytheregulatorybodyisaniterativeprocessandisdescribedinfurtherdetailinPart3(Section3.4).Bysettingthedischargelimitsandconditionsunderwhichthepracticeisauthorized,theenvironmentisassumedtobeprotectedfromtheeffectsofionizingradiation.SomeMemberStatesconsiderthat,inadditiontotheoptimizationoftheprotectionofthepublic,itmaybenecessarytoassessprotectionoftheenvironmentexplicitly,including,forinstance,estimationoftheimpactofradiationexposureonpopulationsoffloraandfauna.ThisisdescribedinmoredetailinPart3(Section3.4).37Issuance,inspectionandenforcementofauthorizationTheregulatorybodyisresponsibleforissuinganauthorizationfordischarges.AsstatedinParagraph5.59ofGSG-9[9]“Theauthorizationfordischargesshouldtaketheformofwrittenpermissionfromtheregulatorybody.”Theauthorizationincludesspecificoperationallimitsandconditionsplacedonthedischarges.Paragraph5.60ofGSG-9[9]goesontosaythat“Theregulatorybodyshouldrecordformallythebasisforitsdecisiononanauthorizationfordischarges,orontheamendment,renewal,suspensionorrevocationoftheauthorizationfordischarges,andshouldinformtheapplicant,inatimelymanner,ofitsdecision,includingthereasonsandjustification.”Requirement31ofGSRPart3[8]onradioactivewasteanddischargesstatesthat“Relevantpartiesshallensurethatradioactivewasteanddischargesofradioactivematerialtotheenvironmentaremanagedinaccordancewiththeauthorization.”Therefore,oncetheregulatorybodyhasformallyauthorizedthedischarge,thedischargecancommenceaccordingtotheoperationallimitsandconditions(includingdischargelimits)setoutintheauthorization.Theregulatorybodyshouldthenreviewperformanceagainsttheauthorization.Paragraph5.92ofGSG-9[9]specificallyrequiresthat“Theregulatorybodyshouldverifycompliancewiththeregulatoryrequirementsandtheoperationallimitsandconditionsoftheauthorizationfordischarges.”Paragraph5.93goesontostatethat“Theregulatorybodyshouldestablishaprocessforidentifyingandmanaginganyidentifiednon-compliancewiththeregulatoryrequirementsondischarges.”ProcessforreviewingauthorizationTheinternationalsafetystandardsrequirethattheregulatorybodyperformsaperiodicreviewoftheexistingauthorization.Paragraph5.10ofGSG-9[9]statesthat“Theauthorizationfordischargesshouldbereviewedduringtheoperationstage,forexampleaspartofaperiodicsafetyreviewofthefacilityoractivity.Significantchangesinanyconditionthatcouldaffectpublicexposureshouldbetakenintoaccountduringthereviewofanexistingauthorization.”3.1.2ReviewandAssessmentEstablishingregulatoryframeworkandregulatorybodyOverthetwomissionsfocusedontheNRA(seeAnnex1),theNRAdescribed:theestablishmentoftheNRAastheregulatorybody,aftertheaccidentatFDNPS;theresponsibilitiesandfunctionsoftheNRA;andthecoordinationofdifferentJapaneseauthoritiesfortheALPStreatedwaterdischarge.TheNRAwentontoprovideanoverviewofthelegalstructureforsafety,whichincludestheAtomicEnergyBasicAct,theReactorRegulationAct,cabinetorders,NRAordinances,regulatoryguidesandtechnicaldocuments,whenappropriate.TheNRAalsohighlightedtheuniquelegalandregulatoryframeworkthatpertainstoFDNPSanditsstatusasa‘SpecifiedNuclearFacility’undertheReactorRegulationAct.Annex4hasfurtherinformationontherelevantlegalandregulatoryprovisionsappliedtotheFDNPS.TheNRAprovidedanoverviewofhowtheALPStreatedwaterdischargeiscoordinatedacrosstheGovernmentofJapanandwithdifferentcompetentauthoritiesandagenciesfromalegal,policymakingandtechnicalperspective.TheNRAnotedthatdecision-makingforhandlingALPStreatedwaterissuesiscoordinatedthroughtheInter-MinisterialCouncilforContaminatedWater,TreatedWaterand38DecommissioningIssues.ThiscouncilincludesrepresentativesfromdifferentministriesincludingMinistryofEconomy,TradeandIndustry(METI),MinistryofAgriculture,ForestryandFisheries(MAFF),andMinistryofEnvironment(MOE),MinistryofEducation,Culture,Sports,ScienceandTechnology(MEXT).TheNRAChairmanattendstoprovidetechnicalandscientificadvicetothecouncil,butnottoparticipateindecisionmaking.TheNRAfurtherdescribedtheroleofthecouncilastheentitythatfacilitatedthedecisionontheBasicPolicyandhowitwillbeimplemented.Overthetwomissions,theTaskForcedevelopedaclearunderstandingoftheapproachfollowedbytheGovernmentofJapanwithregardtotheproposedALPSdischarge.TheTaskForcewasabletoconfirmthattheNRAservesastheindependentregulatorybodywithinJapan,haspromulgatedandimplementedanappropriatelegalandregulatoryframeworkforsafety,andholdstheresponsibilityforassessingthesafetyoftheproposeddischargeofALPStreatedwater.ProcessforauthorizationInthefirstmissiontoNRA,NRAexplainedthatthedischargeofALPStreatedwaterisacontrolleddischargeandthereforeNRAconsiderstheactivitytobeaplannedexposuresituationthatrequiresauthorization.However,NRAwentontoexplainthatthedischargescannotbemanagedusingtheirtraditionalregulatoryapproachbecauseFDNPSpresentsauniquesituation.TheNRAprovidedasanexamplethefactthateventhoughtherearenoexistingexplicitrequirementsorguidancefortheapplicanttoconductanREIA,theNRAdecidedtoreviewtheREIAconductedbyTEPCOtoensurethatTEPCO’splanisinlinewiththeBasicPolicy.Asaconsequenceofthisless-prescriptiveapproach,theprocessforauthorizationwasakeytopicofdiscussionduringthesecondmissionatwhichpointthedomesticregulatoryprocesshadprogressedsignificantly.DuringfurtherdiscussionswithNRA,itbecameapparentthattheImplementationPlanforFukushimaDaiichiNuclearPowerStationSpecifiedNuclearFacility,preparedbyTEPCO,isacoredocumentwithintheauthorizationprocess.Thisdocumentisbroadlyreferredtoasthe“ImplementationPlan”withinthisreport.InresponsetotheBasicPolicy,TEPCOhassubmittednumerous“ApplicationDocumentsforApprovaltoAmendtheImplementationPlanforFukushimaDaiichiNuclearPowerStationSpecifiedNuclearFacility”toincludedetailsofthedesignandoperationoffacilitiesforthedischargeofALPStreatedwater,andanassociatedradiologicalenvironmentalimpactassessmentofdischargingtheALPS-treatedwaterintothesea.NRA’sreviewofthisamendedImplementationPlaniscoretotheauthorizationprocess.SeeAnnex3foralistoftherevisionstotheImplementationPlansubmittedduringtheIAEA’ssafetyreview.NRAsummarisedtheprocessforapprovingtheImplementationPlanandauthorizingthedischargeofALPStreatedwater,asfollows:1.RequirementsarelistedinReactorRegulationActandtheBasicPolicyfordischargeofALPStreatedwater.2.TEPCOwritestheImplementationPlan(orrevisionsthereto)toreflectallrelevantregulatoryandlegalrequirementsandsubmitstheImplementationPlantoNRAforreview.3.NRAreviewstheImplementationPlananddocumentsitsfindingsinthe“ReviewResultsDocument”.4.OncetherevisedImplementationPlanisapprovedbyNRA(i.e.,NRAconfirmsthattheImplementationPlanmeetsallrelevantregulatoryandlegalrequirements)thentheImplementationPlanbecomesthelegallybindingdocumentthatdescribestheoperationallimitsandconditions.5.NRAperformsinspectionsaspartofitsroutineregulatoryoversighttoensurethatTEPCOcomplieswithallaspectsoftheapprovedImplementationPlan.39Aspartoftheauthorizationprocess,reviewmeetingsareheldbetweenTEPCOandNRAtodiscussanditeratetheImplementationPlan.Thesereviewmeetingsareopentothepublic.Furthermore,priortoapproval,NRApublishesthedraftReviewResultsDocumentfor30daysofpublicreviewandcomment.TheNRAconsiderssubmittedcommentstodeterminewhetherchangesarerequired.Followinganychanges,theNRACommissionapprovesthefinalReviewResultsDocumentandtheproposedrevisionstotheImplementationPlanareofficiallyaccepted.FortheALPStreatedwaterdischarges,giventhatnewfacilitiesarebeingconstructed,theauthorizationprocessconcludesonlyfollowingfinalpre-serviceinspectionstoconfirmthattherelevantequipmentandfacilitiesareinstalledandreadytobeoperatedinaccordancewiththeapprovedImplantationPlan.EstablishingdoseconstraintsAfterdiscussionsbetweentheTaskForceandMETI/TEPCOduringthefirstmission,theTaskForcenotedthattheconceptofadoseconstraintdoesnotexistinJapaneselaw.FollowingdiscussionswiththeTaskForce,NRAconfirmedthatthecriterionof0.05mSvperyearestablishedbyNRAforthedischargeofALPStreatedwater–whichistheoperationaltargetfornuclearpowerstationsinJapan–couldbeinterpretedasadoseconstraint.Paragraph5.16ofGSG-9[9]statesthat“inpracticalterms,doseconstraintsshouldbeselectedwithintherangeof0.1tolessthan1mSvinayear”.Withthisinmind,theTaskForcenotedthattheselecteddoseconstraintof0.05mSvperyearisbelowthisrangeandisthereforeconservative.DuringthefirstmissiontoNRA,NRAexplainedthatinadditiontothecriterionestablishedbyNRAfortheALPStreatedwaterdischarges(0.05mSvperyear),NRAusesaseconddosecriterionfromtheReactorRegulationAct(1mSvperyearfromahypotheticalextremesituationatthesiteboundary).TheTaskForcenotedthatthedifferencesbetweenthesetwocriteriaaredifficultforinterestedpartiestounderstandandthatitshouldbeclearlyexplainedwhenestablishingthedoseconstraintfortheALPStreatedwaterdischarge.Duringthesecondmission,theNRAfurtherexplainedtotheTaskForcethedifferencebetweenthetwodosecriteria.ThedosecriterionfromtheReactorRegulationActisforthewholeFDNPSsite,whichismanagedasanexistingexposuresituation.Consequently,NRArequiresthattheadditionaleffectivedoseresultingfromahypotheticalextremesituationatthesiteboundaryislessthan1mSvperyear.NRAindicatedthatveryconservativeassumptionsaremadeinassessingthedosefromalltheexposurepathwaysconsideredforcomparisonwiththe1mSvperyeardosecriterionatthesiteboundary.ThedosecriterionforALPStreatedwaterdischargeisadoseconstraintof0.05mSvperyearfromALPStreatedwaterdischargetotherepresentativepersonusinghabitdatatypicalofthepopulationlivingintheregion.Insummary,NRAexplainedthatthedischargeofALPStreatedwaterisacontrolleddischargeandthereforeNRAconsiderstheactivitytobeaplannedexposuresituation.However,thisisoccurringwithinthecontextofthelargerFDNPSsite,whichismanagedasanexistingexposuresituation.Therefore,twodosecriteriaarebeingusedbyNRA.TheTaskForceunderstandswhythesetwocriteriaareusedbyNRAandnotedthattheuseofthetwodosecriteriaisnotanissueofconsistencywiththeinternationalsafetystandards.However,theTaskForcebelievesthathavingtwodosecriteria,apparentlybothrelatingtothedischargeofALPStreatedwaterbutcalculatedinverydifferentways,couldbeasourceofconfusionforinterestedparties.Therefore,theTaskForcevieweditasimportantforNRAtodevoteefforttowardsexplainingthisdifferencetothepublictoavoidunnecessaryconfusion.TheTaskForceacknowledgedtheimportanceoftheconsiderationofthewholeFDNPS.Toavoidconfusion,theTaskForceadvisedthatthewholesiteshouldbetakenaccountofwhenoptimisingprotectionforthedischargeofALPStreatedwater.40EstablishingrequirementforoptimisationofprotectionOptimizationofprotectionisfundamentaltotheauthorizationofdischarges(SF-1,GSRPart3andGSG-9)andhasthereforebeenasignificantcomponentofIAEA’sreview.TheTaskForceconfirmedthatitisinterestedonlyinoptimizationofprotectionassociatedwithdischargesofALPStreatedwater.DuringthefirstmissiontoNRA,theTaskForcehighlightedhowdoseconstraintsareusedbytheoperatorasaboundaryconditionwhendefiningtherangeofoptionsforthepurposesofoptimizationofprotectionandsafetyofmembersofthepublic,andthatthisinturninformsthesettingofdischargelimitsbytheregulatorybody(seeFigure3.1.).DuringthesecondmissiontoNRA,theNRAprovidedtheTaskForcewithdescriptionsofwhereitspecifiestherequirementforoptimizationofprotection.Firstly,theNRAhighlightedthetextfromthe“SpecificRegulatoryRequirements”thatdescribestherequirementforoptimizationofprotectionfromtheoverallsiteagainstthereferencelevelof1mSvperyear.TheNRAalsostatedthatthedoseconstraintof0.05mSvperyearwassetfordischargesofALPStreatedwater“withtherecognitionthatoptimizationofprotectionistobeconsideredintherangebelowthedoseconstraint”.Subsequently,theNRAconfirmeditwillcontinuetoevaluatewhetherALPStreatedwaterdischargescontributetotheprogressofdecommissioning.Whenrevising‘MeasuresforMid-termRiskReductionfordecommissioningTEPCO’sFukushimaDaiichiNPS’,NRAwillrequireanexplanationfromTEPCOregardingoptimizationofprotectionbasedontheiroperationalexperienceofthedischarges.TheTaskForceacknowledgedthesereferencestooptimization.EstablishingdischargelimitsfortritiumDuringthefirstNRAmission,theTaskForcenotedthatthedischargelimitfortritiumispre-definedintheGovernmentPolicyfordischargesofALPStreatedwateras22TBqperyear,whichisequivalenttothepre-accidentdischargelimitsatFDNPS.TheTaskForcerecognizedthatthevalueof22TBqperyearisfixedandnotedthatthevaluehasbeenchosenwithoutreferencetothedosetotherepresentativepersoncalculatedintheREIAandtheoptimizationofprotectionandsafety.However,theTaskForceunderstandsthatdischargelimitssetingovernmentpolicywereinfluencedbyawiderangeofprevailingcircumstances,suchassocietalconcernsandadesiretoreduceradioactivitybeingreleasedtotheenvironment,andthatthesefactorsdominatedtheoptimizationprocess.TheTaskForceiscontentthatthisisconsistentwiththerequirementforoptimizationofprotectionintheIAEAinternationalsafetystandards.TheTaskForcenotedthatthedosespredictedintheREIAaresignificantlybelow(morethan1,000timeslowerthan)thedoseconstraint.Therefore,theTaskForceemphasisedtheimportanceofrequiringoptimisationofprotectioninthefuturetoinformtheNRA’sreviewofdischargelimits,notingthatthatoptimizationisnotthesameasdoseminimization.Furthermore,theTaskForcenotedthatitishelpfultoshowinterestedpartiesthatahigherdischargeratewouldstillmeetthedoseconstraintandthatthedischargelimitdefinedingovernmentpolicyisalreadysufficientlyconservativetotakeaccountofsocietalconcern.TheNRAinformedthetaskForcethatTEPCOplanstoperiodicallyrevisittheannualamountoftritiumtobedischargedtakingintoaccountfactorstobeconsideredintheoptimizationprocess.TheNRAalsostatedthatifdischargesofALPStreatedwaterhamperstheprogresswithdecommissioning,itmightrequireTEPCOtoreconsiderthedischargeamountbelowtherangeofthedoseconstraint.TheTaskForceemphasizedtoNRAthatrevisingthedischargelimitfortritiumwillhaveimplicationsfordischargelimitsforotherradionuclidesaswellasotheroperationallimitsandconditions.41EstablishingdischargelimitsforotherradionuclidesTheNRAexplainedthatitdoesnotintendtosetdischargelimitsforotherradionuclidesbecausetritiumistheonlyradionuclidethatcannotberemovedbyALPStreatmenttomeetexistingregulatoryconcentrationlimitsforthedischargeofradioactiveeffluentsintotheenvironment(regulatoryconcentrationlimitsareestablishedinthe“NotificationEstablishingDoseLimits,etc.BasedontheProvisionsoftheRegulations,etc.ConcerningtheRefiningBusinessofNuclearSourceMaterialorNuclearFuelMaterial”).Allotherradionuclidesaresubjecttooperationalconditionsbasedontheseregulatoryconcentrationlimitsalongwitharequirementthatthesumofratios(i.e.,thesumofeachradionuclideconcentrationinthedischargedividedbytheregulatoryconcentrationlimits)needstobelessthanone.ContaminatedwateristreatedbyALPSuntiltheseregulatoryconcentrationlimitsaremet.ThedischargelimitfortritiuminBqperyearandtheregulatoryconcentrationlimitsforotherradionuclidesinBqperlitreworktogethertocontrolthequantityofotherradionuclidesdischarged.TheTaskForceunderstandsthelogicfornotsettingdischargelimitsforradionuclidesotherthantritium.However,theTaskForcealsonotedthatadditionaldischargelimitsmayberequired,ifthedischargelimitfortritiumischangedinthefutureasaresultofoptimisationofprotectionbyTEPCO.TheNRAagreedwiththeTaskForce’sobservationsinthisregardandtheTaskForcehasnotedthatthistopicwillbepartoftheon-goingreviewbytheIAEAinthefuture.Separately,theTaskForcenotedthattheregulatoryconcentrationlimitsarebasedonaveryconservativescenariothatisunrelatedtotheexposurepathwaysforthedischargesofALPStreatedwater;theconcentrationlimitsarebasedonadoselimitof1mSvperyeartoahypotheticalpersonatthesiteboundarywhoisdrinking2litresofwaterperdayratherthanadoseconstraintof0.05mSvperyeartoarepresentativeperson.TheTaskForcenotedthatapplyingtheseconservativeconcentrationlimitstodischargesisresultingintheneedfordilutionoftheALPStreatedwaterpriortodischarge,andthatcareshouldbetakennottoimplythatdilutionisperformedforthepurposesofradiationprotectionandsafety(theREIAconsiderstheamountofradioactivityreleasedintotheenvironmentinayearratherthantheconcentrationatwhichitisdischarged).TheTaskForceacknowledgedthatJapanmightchoosetodilutedischargesforotherreasons(e.g.,tokeeplocalradionuclideconcentrationslowatthepointofdischarge,ortomanagereputationalrisks)andadvisedthatthereasonsfordilutionshouldbeclearlystated.Issue,inspectionandenforcementofauthorizationTheNRAdoesnotissueanauthorizationassuch,rathertheNRAreviewstheImplementationPlananddocumentsitsfindingsinthe“ReviewResultsDocument”.OncetherevisedImplementationPlanisapprovedbyNRAthentheImplementationPlanbecomesthelegallybindingdocumentthatdescribestheoperationallimitsandconditionsforthedischarge.NRAthenperformsinspectionsaspartofitsroutineregulatoryoversightprocessestoensurethatTEPCOcomplieswiththeapprovedImplementationPlan.TheTaskForceunderstandsthatNRAisutilisingmultipleprocessestoverifyTEPCO’scompliancewiththeapprovedImplementationPlanwithafocusoninspectionandindependentmonitoringannually(seeSection3.2).TheTaskForceobservedthatlimitsandconditionsintheImplementationPlanaremainlyfocussedonthehardware(e.g.,equipment,etc.)andactionstobetakenifthesearenotmet.However,NRAalsohighlightedthe‘softer’conditions(e.g.,conditionsassociatedwithmanagementsystems,competency,qualitymanagement,etc.)thatarepartoftheImplementationPlanandwithintheQualityManagementSysteminplace.NRAnotedthattheReactorRegulationActstatesthatifoperationalsafetymeasuresperformedbyTEPCOarenotincompliancewiththeImplementationPlan,“NRAmayorderTEPCOtotakemeasuresnecessary42foroperationalsafety,includingsuspensionofdischargeoralterationofthedesignontheDischargeFacility”.NRAexplainedthattheImplementationPlandescribesTEPCO’sresponseto“unusualoccurrences”,“unusualvalues”and“significantdiscrepancies”.However,theTaskForcenotedthatsomeoftheactionlimitsforaresponseortheacceptabletolerancesthatwillbeimplementedarestilltobedefined.TheTaskForceacknowledgedthatitisnotyetpossibletodefinesomeoftheactionlimitsthatarerelatedtoenvironmentalmonitoringbecausethevariationinreportedmonitoringresultshavenotyetbeenfullyestablished.Subsequently,theNRAexplainedthatnecessaryactionlimitsforaresponseortheacceptabletolerancesthatwillbeimplementedwouldbedefinedinTEPCO’sinternaldocumentsbeforethestartofdischarges.ProcessforreviewingauthorizationTheNRAexplainedtheprocessofperiodicreviewtotheTaskForce.TEPCOisrequiredtoupdatetheImplementationPlanwheneverchangesareproposed(includinganychangestothesourceterm,REIA,monitoringprogrammes,etc.),andthattheNRAwillthenreviewtherevisedplanagainsttherequirementsintheReactorRegulationActandGovernmentPolicyfordischargeofALPStreatedwater.OncetherevisedImplementationPlanisapprovedbytheNRAitwillbecomelegallybinding.TheNRAstatedthatperiodicreviewoftheauthorizationofdischargewillbeconductedwithintheprocessofoptimizationofprotectionrelatedtothedecommissioningactivitiesforthewholesite,typicallyonceperyear.TheTaskForcediscussedwiththeNRAtheimportanceofdecidingtheappropriateperiodforthevalidityoftheauthorizationthatwillbeissued,andofselectingcriteriaforfuturereviewofthedischargelimitsorsettingatimeintervalforconductingperiodicreviewofthedischargelimits.TheNRAdescribedtheprocessforreviewingtheauthorizationinthefutureandinformedtheIAEAthatthiswillbeconductedwithintheprocessofoptimizationofprotectionrelatedtothedecommissioningactivitiesforthewholesite,typicallyonceperyear.3.1.3ConclusionsTheIAEAhasconcludedthattheapproachtakenbyTEPCOandNRAisconsistentwiththerelevantinternationalsafetystandardsincludedunderthissectionofthereport.Furtherdetailedfindingsareincludedbelow:•NRAservesastheindependentregulatorybodywithinJapan,haspromulgatedandimplementedanappropriatelegalandregulatoryframeworkforsafety,andholdstheresponsibilityforassessingthesafetyoftheproposeddischargeofALPStreatedwater.•Anauthorisationprocesshasbeenestablished,thecoreofwhichisNRA’sapprovalofthe“ApplicationDocumentsforApprovaltoAmendtheImplementationPlanforFukushimaDaiichiNuclearPowerStationSpecifiedNuclearFacility”submittedbyTEPCO.Duringtheauthorizationprocess,bothpartiesplayaroleinensuringcompliancewithrequirementslistedinReactorRegulationActandBasicPolicy.ItisaniterativeprocessthatincludesaperiodofpublicreviewandcommentonNRA’s“ReviewResultsDocument”.•NRAconfirmedthatthe‘dosetarget’of0.05mSvperyearestablishedbyNRAforthedischargeofALPStreatedwatercouldbeinterpretedasadoseconstraint.Theselecteddoseconstraintof0.05mSvperyearisbelowtherangefromwhichthedoseconstraintshouldbeselectedaccordingtoParagraph6.16ofGSG-9[9].43•NRAhighlightedarequirementinthe“SpecificRegulatoryRequirements”thatdescribestheneedforoptimizationofprotectionfromtheoverallsiteandstatedthatNRAwillrequireanexplanationfromTEPCOregardingoptimizationofprotectionbasedontheiroperationalexperienceofdischargewhenrevising‘MeasuresforMid-termRiskReductionfordecommissioningTEPCO’sFukushimaDaiichiNPS’.•Thedischargelimitfortritiumispre-definedintheGovernmentPolicyfordischargesofALPStreatedwateras22TBqperyear,whichisequivalenttothepre-accidentdischargelimitsatFDNPS.TheTaskForcenotesthatthedischargelimitwasselectedwithoutreferencetothedosetotherepresentativepersoncalculatedintheREIAandtheoptimizationofprotectionandsafety.However,theTaskForceunderstandsthatdischargelimitssetingovernmentpolicywereinfluencedbyawiderangeofprevailingcircumstances,andthatthesefactorsdominatedtheoptimizationprocess.TheTaskForceiscontentthatthisisconsistentwiththerequirementforoptimizationofprotectionintheIAEAsafetystandards.•TheTaskForceencouragedtheNRAtosetdischargelimitsbasedontheREIAinthefutureafteradditionaloperationalexperienceandsamplingdatahasbeencollected;itwouldbehelpfultosetdischargelimitsforradionuclidesthat,accordingtotheREIA,contributemosttothedosetotherepresentativeperson,eventhoughtheoveralldosefromtheseradionuclidesandtritiumisverylow.ThiscouldbeconsideredinthefutureifthedischargelimitfortritiumischangedasaconsequenceofoptimizationofprotectionbyTEPCO.•TheuseofconservativeconcentrationlimitsresultsintheneedfordilutionoftheALPStreatedwaterbeforedischarge.TheTaskForcenotesthatcareshouldbetakennottoimplythatdilutionisperformedforthepurposesofradiationprotectionandsafety.•Aprocessexistsforreviewingtheauthorizationofdischarges,whichwilloccurwheneverTEPCOupdatestheImplementationPlanandalsowithintheprocessofoptimizationofprotectionrelatedtothedecommissioningactivitiesforthewholesite,typicallyonceperyear.3.2.SafetyRelatedAspectsofSystemsandProcessesforControllingDischarges3.2.1BackgroundRequirement13ofGSRPart3[8]statesthat:“Theregulatorybodyshallestablishandenforcerequirementsforsafetyassessment,andthepersonororganizationresponsibleforafacilityoractivitythatgivesrisetoradiationrisksshallconductanappropriatesafetyassessmentofthisfacilityoractivity.”InaccordancewiththerequirementsestablishedinGSRPart3[8],thelicenseeisrequiredtoconductanappropriatesafetyassessmentforthedischargeofALPStreatedwaterfromtheFukushimaDaiichinuclearpowerstationandsubmititforsubsequentreviewandassessmentbytheregulatorybodypriortoauthorization.Thesafetyassessmentaimstoidentifythewaysinwhichexposurescouldbeincurred,todeterminethe44expectedlikelihoodandmagnitudesofexposuresinnormaloperationandtoassesstheadequacyoftheprovisionsforprotectionandsafety.Thesafetyassessmentisrequiredtoincludeareviewoftheoperationallimitsandconditionsfortheoperationofthedischarge;thewaysinwhichstructures,systemsandcomponentsrelatingtoprotectionandsafetymightfail,andtheconsequencesofsuchevents;thewaysinwhichexternalfactorscouldaffectprotectionandsafety;thewaysinwhichoperatingproceduresrelatingtoprotectionandsafetymightbeerroneous,andtheconsequencesofsucherrors.3.2.2IAEAReviewandAssessmentDuringitsreview,theTaskForceconsideredthesafetyassessmentincludedintherevisedImplementationPlan,andotherassociatedoperationaldocumentscreatedbyTEPCOinpreparationforthebeginningofdischarges.TherevisedImplementationPlan,approvedbyNRAon22July2022and10May2023,includesanumberoftechnicaldescriptionsofthefacilities,equipment,andprocessestobeusedaspartoftheplanneddischargesofALPStreatedwater.Thisinformationissummarizedbelow,howeverfurtherdetailscanbefoundinthepubliclyavailableversionoftherevisedImplementationPlan.ThefacilitiesandequipmentinstalledbyTEPCOtofacilitateandmanagethedischargeofALPStreatedwaterarecomprisedoffourmaincomponents:theMeasurementandConfirmationFacility,theTransferFacility,theDilutionFacility,andtheDischargeFacility.Furtherdetailsoneachothercomponentsareincludedbelow.Measurement/ConfirmationFacilityThisfacilityiscomposedby35tankseachwithasizeofapproximately1,000m3,locatedintheK4tankarea.Thereare3groupsof10tanksplusanadditional5tanksforstorage.Thethreetankgroups(10tankseach)fulfiloneofthreefunctionsatanygiventime:receiving,measurementandconfirmation,anddischarge.ThetankgroupsfulfiltheserolesinarotatingbasisashighlightedbelowinFigure3.2.ThetankgroupresponsibleforreceivingwillbeemptyinitiallyandwillbefilledwithwaterfromtankselsewhereontheFDNPSsiteeitherdirectly,orafterundergoingsecondarytreatmentbyALPS.Thetankgroupresponsibleformeasurementandconfirmationwillbehomogenizedusinginstalledagitatorsandcirculationpumps,forapproximatelyoneweek,beforesamplingisconducted.ThesamplestakenbyTEPCOwillbeanalysedforawiderangeofradionuclidesandafterapproximatelytwomonthstheresultswillbeavailable.Aftertheanalyticalresultsareavailable,TEPCOwillensureallrelevantregulatorydischargelimitsaremetandwillcalculatethenecessarydilutionrequiredtokeeptheoveralltritiumdischargeat1,500Bq/Lorless.Topreventhumanerror,thetritiumconcentrationconfirmedintheprocessofmeasurementandconfirmationwillbemechanicallyreadbyascannerandregisteredinamonitoringandcontroldevice.ThemonitoringandcontroldeviceautomaticallycalculatesanappropriateflowrateforALPStreatedwaterfromthedischargetankgroup.45(1)ReceivingProcessTheALPStreatedwaterinALPStreatedwaterstoragetanksetc.isreceivedbyanemptytankgroup.Group1(10tanksapprox.10,000m3)(2)Measurements/confirmationprocessAfterthewaterqualityofthetankgroupishomogenizedbyagitatingequipmentandcirculationpump,samplingiscarriedouttoconfirmwhetherthedischargestandardissatisfied.5tanks5tanks3)DischargeprocessAfterconfirmingthatthedischargecriteriaaresatisfied,theALPStreatedwateristransferredtothedilutionfacilitybythetransferfacility.Group1(10tanksapprox.10,000m3)GroupA(10TANKS)GroupB(10tanks)GroupC(10tanks)(5tanks)FromALPStreatedwaterstoragetanksetc.AgitatingequipmentTransferExistingtransferpipingisusedforreceiving.PPCirculationpumpCirculationpumpTothesamplingdeviceFromthesamplingdeviceTothesamplingdeviceFromthesamplingdeviceK4-A1K4-A2K4-A3K4-A4K4-A5K4-A10K4-A9K4-A8K4-A7K4-A6K4-B1K4-B2K4-B3K4-B4K4-B5K4-B10K4-B9K4-B8K4-B7K4-B6K4-C1K4-C2K4-C3K4-C4K4-C5K4-D10K4-D9K4-D8K4-D7K4-D6K4-E1K4-E2K4-E3K4-E4K4-E5K4areatankgroup:35tanksALPStreatedwaterdilution/dischargefacilityStoragetankforALPStreatedwater,etc.GroupAGroupBGroupCReceivingMeasurement/confirmationDischargeReceivingMeasurement/confirmation-ReceivingMeasurement/confirmationDischargeReceiving--ReceivingMeasurement/confirmationDischarge1stcycle2stcycle3stcycle4stcycle-Figure3.2.Processforreceiving,measuringanddischargingALPStreatedwaterTransferFacilityThetransferfacilityiscomposedoftransferpumps,piping,valvestocontroltheflow,andflowmetersandradiationdetectors.Eachpumphasa30m3/hourcapacity,andtheflowrateismanagedbasedonoperationalneeds(seeFigure3.3).Thepumpsareinstalledinthetransferfacilitybuildingnearthemeasurement/confirmationfacilitytotransferALPStreatedwaterfromthetanksofthemeasurement/confirmationfacility33.5mabovesealeveltothedilutionfacilitywhichisdownstream.Aradiationdetector(sodiumiodidescintillationdetectors)todetectgammaraysisinstalledoneachtransferlineandisdesignedtoprovideaqualitativescreeningpriortothetreatedwaterreachingthedownstreamdilutionfacility.Analarmvaluewillbesetforthedetectorsthatwouldtriggertheemergencyisolationofthetransferlinesifthevaluewereexceeded.Inthetransferfacility,thetransferpipingisinstalledtoconnectthemeasurement/confirmationfacility33.5mabovesealeveltothepipinginthedilutionfacility2.5mabovesealevel.AlongthispipingemergencyisolationvalvesareinstalledtoenableTEPCOtoimmediatelystopthetransferoftreatedwatershouldanabnormalitybedetected.OneemergencyisolationvalveisinstalledjustbeforetheALPStreatedwaterfromthetransferfacilityreachestheseawaterheader.TheotheremergencyisolationvalveisinstalledintheALPSelectricalequipmentroomsetupinsidetheseawall11.5mabovesealevelinpreparationforthepossibilitythattheotheremergencyisolationvalvedoesnotwork(e.g.,duetoinundationduringa46tsunami).Inthesameelectricalequipmentroom,flowmetersandadditionalvalvesareinstalledtoallowforfurtheroperationalcontrolofthedischargerate.ALPStransferfacilitybuildingALPSelectricalequipmentroomRadiationDetector(A)ALPStreatedwatertransferpump(B)ALPStreatedwatertransferpump(A)PPMOMOMOMOAmaximumofabout500m3/dayisassumedbasedonthetritiumconcentrationinALPStreatedwaterandtheannualamountoftritiumdischargedFlowmeter(A)Flowmeter(B)Emergencyisolationvalve-1(A)Emergencyisolationvalve-1(B)EmergencyisolationvalveinfrontofheaderpipeInstallationinfrontoftheseawatertransferpipinginlettominimizetheamountofdischargeSeawallAOAOEmergencyisolationvalve-2(A)Emergencyisolationvalve-2(B)DischargeverticalshaftTo(upstreamwatertank)SeawallpipeInstalledwithintheseawallfromtheviewpointoftsunamicountermeasuresFCV(A)FCV(A)Measurement/confirmationtank(K4areatank)MO:Motor-operatedAO:AiroperatedFCV:WaterflowratecontrolvalveFigure3.3.TransferFacilityDilutionFacilityThisdilutionfacilityconsistsofthreeseawatertransferpumps,pipingforeachseawaterpumptomovetheseawatertoasinglelargeseawaterheader,andadischargeshaft(upstreamwatertank)(seeFigure3.4).TheoverallpurposeofthispartoftheprocessistoensuretheALPStreatedwaterisdilutedwithseawaterpriortoreachingtodischargefacility.DilutionisdonebyinjectingALPStreatedwaterintotheseawaterpipeheaderandallowingittoundergoturbulentmixing.Thedilutionfacilityisinstalledinalocation2.5mabovesealevelintheseasideofFDNPSUnits5and6.AflowmeterisinstalledoneachofthethreeseawatertransferlinestoensureprecisecontroloverthedilutionfactorthatiscalculatedbyTEPCOforeachbatchofALPStreatedwatertobedischarged.Fortheseawatertransferpumps,theintakechannelfortheexistingUnit5circulationwaterpumpisreused.Conservatively,threepumps(onepumpoutofthreeisforspare)areinstalled.BecausedilutionisperformedbyinjectingALPStreatedwaterintotheseawaterpipeheader,TEPCOanalysedthebehaviourofthewaterintheseawaterheaderanddownstreampiping.TEPCOcalculatedtheexpecteddilutioneffectandconcludedthatthewaterisdilutedmorethan350timesbythetimeitleavestheseawaterheader.47ButterflyvalveCheckValvePFlowmeter(A)SeawatertransferpumpAPFlowmeter(B)SeawatertransferpumpBPFlowmeter(C)SeawatertransferpumpCDischargeverticalshaft(upper-streamstorage)WaterdischargetunnelsFromtransferfacilitySeawaterpipheaderFigure3.4.DilutionFacilityDischargeFacilityThedischargeoftreatedwateroccursthroughatunnelrunningundertheseabedaboutonekilometreoffthecoastofFDNPS.Thedischargefacilityconsistsofthedischargeverticalshaft,dischargetunnel,anddischargeoutlet,andisdesignedtotransferwaterflowingoutoverthepartitionwall(weirwhichseparatestheupper-streamstoragefromthedown-streamstorage)inthedischargeverticalshafttotheoutlet,bymakinguseofthedifferenceinheightbetweenwaterinthedischargeverticalshaft(down-streamstorage)andtheseasurface.Thedischargetunnelpassesthroughstablebedrocktominimizetheriskofleakageandimproveseismicresistance.Additionally,thedischargeoutletissetwithinanareawherecommercialfishingisnotconductedonaregularbasis.PlaneviewSectionalViewDischargeoutletWaterdischargetunnelsLength:Approx.1kmWaterintakeWaterintakereservoirPartitiondikeLengthofthisreservoirtobeconstructed.Approx.65mDilutionfacilitiesDischargeverticalshaftDischargeverticalshaft(downstreamwatertank)WaterdischargetunnelsDischargeoutlet48Futbatown3.5kmnorthtosouth1.5kmnorthtosouthAreawherenofishingisconductedonadailybasisWaterdischargetunnelsAreaswherecommonfisheryrightsarenotestablishedNFigure3.5.a)andb).PositionofdischargetunnelforALPStreatedwaterSafetyAssessmentInordertoassesstheconsistencyoftheapproachwiththerelevantinternationalsafetystandards,theTaskForcereviewedthesystemsandequipmentthatwereincludedinthedesignfortheALPSfacilitiesnotedabove.TheImplementationPlan,whichisapprovedbyNRA,includesthevarioustechnicalspecificationsoftheequipmentandprocessesinplacefortheALPSdischarges(e.g.,SectionII.2.50.2.1oftheImplementationPlan).TheImplementationPlanservesasaregulatoryauthorizationforTEPCOatFDNPSandthereforewhendetailsareincludedintheplan,andapprovedbyNRA,theymustbeadheredtobyTEPCO.TheTaskForcereviewedtheinformationpresentedinallversionsoftheImplementationPlanthatwereprovidedthroughout2021,2022,and2023.Inparticular,theTaskForceobservedthatTEPCOhadincludedtherelevantmaterials,tolerances,technicalspecifications,andlayoutsforalltheequipmentandstructuresnecessarytooperatetheALPSdischargeprocess.Asanexample,TEPCOhasincludedmaterialrequirementsthatareintendedtoavoidleakageovertimefromcorrosionandmanycomponentsandstructuresarebuilttoavoiddamageduetoseismicactivity.TheIAEAnotesthattherobustdesignandengineeringfeaturesbuiltintotheALPSdischargesystem,includingredundantsystemsaremorethanadequategiventheexpectedlowdoseandlowriskfromtheoperationofthedischargeprocess.TheImplementationPlanalsoincludesprovisionsnecessarytomeetthevariousoperationallimitsandconditionsapplicablefortheALPSdischargeprocess.Themainoperationallimitsandconditionsthatapplycanbesummarizedas:•Limittheoveralldischargeoftritiumtotheenvironmentatnomorethan22TBqperyearonanannualbasis;•Limitthetritiumconcentrationindischargedwatertonomorethan1,500Bq/L;•Dischargedwatermustmeetthenationalregulatorylimitsfortheconcentrationofvariousradionuclides;•Engineeredfeatures(e.g.,emergencyisolationvalves)andoperationalproceduresareinplacetoensurethatthetransferofALPStreatedwatercanstopimmediatelyupondetectionofanyabnormalevents.49AsnotedinFigure3.6andFigure3.7multiplecheckshavebeenincludedthroughoutthesystemtoavoidanyunintendedreleaseofALPStreatedwaterthatdoesnotmeetthecriteriaabove.Furthermore,redundantsafetyfeaturesareinstalledintothesystemtoensurethatfailureofasinglecomponentwillnotresultintheviolationofanyoperationallimitsandconditions.However,aswouldbeexpected,thesafetyassessmentincludescarefulconsiderationofhowabnormaloccurrenceswillbeidentifiedandaddressed.SectionIII.3.1.9.3oftheImplementationPlan[15]includessignificantdetailontheoperationofthedischargeprocesstoensuretheemergencyshutdownofthesystemispossibletoensureany“unintentionaldischargeofALPStreatedwaterintothesea”isavoided.ThesystemincludesengineereddesignfeaturestoallowalarmstoautomaticallyshutdowntheALPSdischargeprocess,aswellasproceduralfeaturestoallowoperatorstoshutdowntheprocessshoulditbedeemednecessary.Figure3.6and3.7highlighttheprocessanddesignfeaturesutilizedbyTEPCOtoensureanemergencyshutdowncanbeperformedwhenneeded.Examplesofthealarmsorconditionssettoallowforanautomaticemergencyshutdowninclude:•Failureofflowmeters•AhighflowrateofALPStreatedwateroralowflowrateofseawaterfordilution•Theunexpectedshutdownofpumps•Ahighreadingoninstalledradiationmonitors(i.e.,abovethesetalarmlevel)•CommunicationabnormalitieswiththeemergencyisolationvalvesEmergencyisolationvalve-1,2“close”activationFCV“close”activationALPStreatedwatertransferpumpshutdownOtherMOvalves"close"activationOperationsystemNormalShutdownEmergencyShutdownShutdownmethodShiftteamProcessshutdown(doubleaction)Emergencyshutdown(doubleaction)Since“[9}Bothseriesofemergencyisolationvalvepanelcommunicationabnormalities”issupposedthatcommunicationabnormalityofcontrolpanelforemergencyisolationvalveandoperationofsystemisexpectednofailure,weplanthesamesuspendingprocessasnormalshutdownoperation.Emergencyshutdownevent(1)ALPStreatedwaterflowmeterfailure(2)Seawaterflowmeterfailure(3)ALPStreatedwaterflowrateHIGH(4)SeawaterflowrateLOW(5)ALPStreatedwatertransferpumptrip(6)Seawatertransferpumptrip(7)Radiationmonitorpanel,majorfailure(8)RadiationmonitorHIGH(9)BothseriesofemergencyisolationvalvepanelcommunicationabnormalitiesMonitoring/controldeviceTransferFacilityMeasurements/confirmationtankwaterlevellowdetectedEmergencyshutdowneventdetectedDischargeshutdownEmergencyshutdown(9)(1)to(8)FCV“close”activationALPStreatedwatertransferpumpshutdownEmergencyisolationvalve-1“close”activationOtherMOvalves"close"activationManualshutdownintheeventsuchasanearthquakewithseismicintensityof5-oraboveoranissuanceoftsunamiadvisoryshallbecarriedoutwithfollowingoperationsFigure3.6.ProcessfornormalandemergencyshutdownoftheALPSdischarge50MO(4)MO(4)MO(4)MO(4)MO(1)AO(1)FCV(2)MO(4)MOMOMOMOMOMOREREFITFITMOMOMOMOFCVFITGroupAGroupBGroupCMO(4)MO(4)MOMOMOMOALPStreatedwatertransferpump(B)ALPStreatedwatertransferpump(B)To’2To’2To’1(3)Measurement/confirmationtankFrom’2(1)Emergencyisolationvalveclosed(2)FCVclosed(3)ALPStreatedwatertransferpumpshutdown(4)OtherMOvalvesclosedMonitoringandcontroldevice[1]ALPStreatedwaterflowmeterfailure[2]Seawaterflowmeterfailure[3]ALPStreatedwaterflowrateHIGH[4]SeawaterflowrateLOW[5]ALPStreatedwatertransferpumptrip[6]Seawatertransferpumptrip[7]Radiationmonitorpanel,majorfailure[8]RadiationmonitorHIGH1.Emergencyshutdowneventoccurrence2.Dischargeshutdown(Automatic)AO(1)Seawatertransferpump(A)Emergencyisolationvalve-2(A)Emergencyisolationvalve-2(A)Emergencyisolationvalve-2(B)Emergencyisolationvalve-2(B)From’2MOMOFITSeawatertransferpump(B)MOMOFITSeawatertransferpump(C)SeawaterpipeheaderFigure3.7.EngineereddesignfeaturesforautomaticshutdownoftheALPSdischargeprocessTheALPSdischargesystemisalsodesignedtoallowforamanualshutdownbasedontheoperator’sconsiderationofnaturalphenomena.AseriesofeventshavebeenidentifiedintheImplementationPlanthattheoperatorwillconsideratalltimes.Forexample,anoperatorwillmanuallyshutdowntheALPSdischargeprocessintheeventatsunamiadvisory,hazardouswindwatch,orhightidewarningareissued.Whilethesystemisrobustlydesignedandtherisktothepublicfromanabnormaloccurrenceisminimal,aconversativeapproachhasbeenadoptedbyTEPCO[15]andapprovedbyNRAinthisregard.51TEPCOhasanalysedtheprocessforpotentialfailuresandidentifiedthreemainabnormaleventsthatareusedtoassessfor“initiatingeventsandcauses.”Table3.1belowshowsthesethreeabnormalevents.Table3.1.ListofabnormaleventsfromtheImplementationPlan.Abnormalevents[Definition(1)]Aneventofdischargingwithdefectivemeasurements/confirmationofradioactivematerial(defectivemeasurements/confirmation)[Definition(2)]Aneventofdischargingwithtritiumconcentrationinthewaterdilutedbyseawaterbeing1,500Bq/Lormore,orwithdilutionratiobeinglessthan100times(insufficientseawaterdilution)[Definition(3)]Aneventofdischargingwithoutseawaterdilutionduetoleakageoutofthesystem(lackofseawaterdilution)TheresultsofTEPCO’sanalysisusingamasterlogicdiagramareincludedinSectionIII.3.1.9.5.1.3oftheImplementationPlan.InspectionsandEnforcementAspartofitswork,theTaskForcealsoconsideredhowthesafetyassessmentwouldbeimplementedinapracticalmannerandwhatmeasuresareinplacetoensurecompliancewiththedetailsnotedabove.TheTaskForcenotedthatthedetailsoftheALPSdischargefacilitiesareincludedintheImplementationPlanforTEPCOandthatthisImplementationPlanservesasthebasisfortheiroperationsandcompliancewithregulations.Therefore,duringthemissionstotheNRAtheTaskForcerequestedupdatesontheplannedinspectionandenforcementprogrammesforFDNPSthatwouldcoverthedischargesofALPStreatedwater.Figure3.8.Pre-serviceinspectionofALPSdischargefacility52NRAprovidedbackgroundinformationontheinspectionandenforcementprogrammesduringbothmissionsfocusedontheNRA.Inthepre-operationalphase,theNRAconductsinspectionscalled“pre-serviceinspections”whichservethepurposeofverifyingthattheinstallationandperformanceofallvariouscomponentsandsystemsthatmakeuptheALPSdischargefacilitiesareensuredpriortothecommencementofoperations.TheNRAhighlightedthatTEPCOisnotauthorizedtobegindischargesuntilallrelevantpre-serviceinspectionshavebeencompletedinasatisfactorymanner.Aspartofitswork,theTaskForceperiodicallyvisitedFDNPStowitnesstheconductofpre-serviceinspections.(seeFigures3.8-3.10)Figure3.9.InspectionoftheconstructionofthedischargetunnelInparticular,theTaskForcewitnessedinspectionstopressuretestthepipinginthetransferfacility,toverifytheoperationofleakdetectionmonitorsandtheiralarmannunciationinthecontrolroom,andtheinspectionoftheconstructionofthedischargetunnelpriortoitbeingfilledwithseawater.TheseactivitieswereconductedsystematicallybytheNRA,usingclearlydefinedbenchmarksforwhatconstitutesacceptableperformance;theresultsoftheseinspectionsarepostedontheNRA’spublicwebpage(inJapanese).Attheveryendofthepre-operationalphase,theNRAconductedaninspectionofTEPCO’sdemonstrationoftheentiresystematonce.Thisfinalpre-serviceinspection,whichtheIAEAwaspresenttoobserve,demonstratedthatallcomponentsandsystemswereinstalledandfunctioningasexpected.53Figure3.10.Pre-serviceinspectionofALPSdischargefacilityTheNRAalsoprovidedanexplanationoftheoperationalinspectionprogrammeinplaceatFDNPSandthecorrespondingenforcementprogrammeinplace.AtFDNPS,NRAmaintainsacontingentofabout10residentinspectorsandalwayshaveatleastoneinspectoron-site,24hoursaday.DuringvisitstoFDNPS,theTaskForceobservedthattheNRAconductsroutineoperationalinspectionsconsistentwiththeirmandateasanindependentsafetyregulatorybodyandprovidedexamplesoftheinspectiondocumentationandenforcementmanualtotheTaskForcefortheirreview.3.2.3ConclusionsTheIAEAhasconcludedthattheapproachandactivitiesundertakenbyTEPCOandNRAareconsistentwiththerelevantinternationalsafetystandardsincludedunderthissectionofthereport.Furtherdetailedfindingsareincludedbelow:•TEPCOhasconductedaspecificsafetyassessmentfortheplanneddischargesofALPStreatedwateratFDNPSthatisappropriateforthepre-operationalandoperationalphases.•TEPCOhasincorporatedrelevantoperationalconditionsandlimitsintheirsafetyassessmentaswellasconsiderationofimportantconceptssuchasredundancyforsafetyrelatedsystemsandpotentialfailuremodes,andtheplannedmaintenanceoffacilitiesandequipmentovertheplanneddischargetimeframe.•TheIAEAnotesthatthesystemsandprocessesinplacetocontrolthedischargesofALPStreatedwaterarerobustandmorethanadequatefortheexpectedlowdosesandthelowriskarisingfromthedischargeprocess.•Furthermore,theIAEAhasnotedthatthepre-serviceinspectionsconductedbytheNRAaresufficienttoensuretheinstallationandoperationofrelevantfacilitiesandequipmentisconsistentwiththeNRA-approvedImplementationPlan;andthattheapproachforincorporatingoversightoftherelevantfacilitiesandequipmentintotheoperationalinspectionprogrammeconductedbyNRAatFDNPSisappropriate.543.3.CharacterizationoftheSource3.3.1BackgroundInaccordancewiththeauthorizationprocessfordischargesdescribedinGSG-9[9],“apre-operationalanalysisshouldbecarriedouttoidentifytheinventoriesofradionuclidesthatwouldresultsindishragsduringtheoperationofafacilityortheconductofanactivity…”Thischaracterization,andthesubsequentidentificationofthemainexposurepathways,ensuresanadequateassessmentoftheexposureoftherepresentativeperson.Further,theregulatorybodyisrecommendedto“evaluatewhetherthemodelsandassumptionsused(forthischaracterization,andthesubsequentidentificationofthemainexposurepathway)areappropriate”toensureanadequateassessmentoftheexposureoftherepresentativeperson.Theneedforadetailedcharacterizationofthedischarges,aspartofthedialoguebetweentheregulatorybodyandtheapplicantontheprocesstobefollowedbyanapplicantseekinganauthorizationfordischarges,shoulddependontheexpectedmagnitudeofthedosetomembersofthepublic,inaccordancewithagradedapproach.InaccordancewithRS-G-1.8[16],aspartofpre-operationalstudiesperformedtodeterminetheimpactsofthesource,includingthepredictionofdosestothepublicfromdischargestotheenvironment,itisnecessarytodeterminetheexpectedactivityinventoryandradiationcharacteristicsofthesource;thetypesandactivitiesofradionuclidesthatwillbedischarged,theirphysicalandchemicalforms,themethodsandroutesofdischargeandtheratesofdischarge.3.3.2ReviewandAssessmentTEPCOhasdevelopedanappropriatelyconservativecharacterisationofthesource.DetailsareprovidedinitsREIASectionI-4(InventoryAssessment)andI-5(Selectionofnuclides)forthemethodologyforselectingtheradionuclidestobemeasuredandassessedpriortodischargeofeachbatchofALPStreatedwater.Thismethodologyiscomprisedof5stepsandcanbesummarisedasfollows.AnoverviewispresentedinFigure3.11.55ConsiderationbasedoninventoryassessmentConsiderationbasedonthemeasurementdataandthepropertiesofthenuclideinadditiontotheaboveLibraryofradioactivenuclidesusedintheinventoryassessment(around1,000nuclides)Arenuclidespresentintheassessmentintheresultsoftheinventoryassessment1?Whethernoblegas(excludedRn)ornot?Doestheratiooftheconcentrationofeachradionuclidetotheregulatoryconcentrationlimitexceed1/100intheassessmentresultsonthetransitionofnuclidestothewaterintheALPStreatedwater,etc.storagetank?Doestheratiooftheconcentrationofeachradionuclidetotheregulatoryconcentrationlimitexceed1/100inthetransitionassessmentofnuclidestocontaminatedwater?Doestheratiooftheconcentrationofeachradionuclidetotheregulatoryconcentrationlimitislessthan1/100ontheanalysisresults2ascontaminatedwaterinthepast?Isittritium(benotabletoremovebyALPS)NuclidestobemeasuredandassessedExclusionExclusionExclusionExclusionExclusionNuclidestobemonitored3Step1Step2Step3Step4Step5NoYesYesYesYesNoNoNoNoNoYesYesFigure3.11.OverviewofmethodologyusedbyTEPCOtoselectradionuclidestobemeasuresandassessedpriortodischargeOverviewofmethodologyusedbyTEPCOtoselectradionuclidestobemeasuresandassessedpriortodischargeSteps1-3werebasedoncalculationsperformedbyTEPCO:•Step1:TheradionuclideinventoriesinUnits1,2and3atFDNPS12yearsaftercoldshutdownwereevaluated.Forthefuel,aninitialinventoryforeachreactorwasestimatedbymultiplyingtheuraniumfractionpertonandthepercentagemassesofeachelementbyanominalmassofthecore.ORIGEN1wasthenusedtoassesstheburnupofeachfuelbundlefromthetimeofloadinguntilthetimeoftheaccident(includingconsiderationofmixed-oxidefuelinUnit3).Fissionproductsresultingfromthenuclearfissionof235U,nuclidesresultingfromtheabsorptionofneutronsby238U,suchasisotopesofplutonium,andnuclidesproducedbywhenfissionproductscaptureneutrons,suchas134Cs,wereassessedusingthiscode.Activationofmaterialscomprisingeachreactorstructurewassimulatedovertheentirecommercialoperationalhistoryofeachunit.Followingthesecalculations,allradionuclidesinthestandardORIGENlibrary(around1,000)determinedtohaveactivitieslessthan1Bqperreactorcore–essentiallyallshort-livedradionuclides–werenotfurtherconsidered.•Step2:Noblegases(thatcannotbepresentincontaminatedwater)wereeliminatedfromtheradionuclideinventoriesevaluatedinstep1.•Step3:Thehypotheticalestimatedmaximumpossibleactivityconcentrationsofallradionuclidesinthetreatedwateretc.storedinthetanksatFDNPSwaterwereestimatedandcomparedtorespectiveregulatorylimits.Itwasassumedthattheentireradionuclideinventoriesofthreereactors(asevaluatedinstep1)weredissolvedinthecurrenttotalvolumeoftreatedwateretc.at1ORIGENisawidelyusedandwellvalidatedsoftwaretoolforsimulatingingrowth,decay,andactivationinPWRandBWRreactors.Thissoftwarewasdevel-opedbytheOakRidgeNationalLaboratoryintheUnitedStates.56FDNPS(1,330,000m3).Anyradionuclidesforwhichtheresultingactivityconcentrationswerelessthan1%oftherespectiveregulatorylimitwereeliminatedfromtheradionuclideinventoriesevaluatedinstep1.Steps4and5incorporatedtheresultsofmeasurementandanalysesforfurtherdown-selection:•Step4:Thepotentialforradionuclidestotransferfromthereactorstothecontaminatedwaterwasassessedandtheresultingactivityconcentrationswerecomparedtorespectiveregulatorylimits.Radionuclideshavingasimilarchemicalforminwaterwerefirstgrouped.Parentradionuclidesandshort-livedprogenywereassumedtobeinequilibrium(afterthe12-yearcooldownperiod),exceptZr-93andNb-93(astheyhavenotreachedequilibriumasof2022).Arepresentativeradionuclidewasdefinedforeachgroup(determinedbycontributiontodose)anda“relativeratio”wascalculatedforeachradionuclide(theratioofitsactivityasevaluatedinstep1totherespectiveregulatorylimit,itselfdividedbythesameratiofortherepresentativeradionuclide).Wheretherelativeratiowaslessthan0.01,theradionuclidewaseliminatedfromtheradionuclideinventoriesevaluatedinstep1.Atransfercoefficientwasthencalculatedfortherepresentativeradionuclideineachgroup(fromtheperiodictable):theratioofitsmaximummeasuredactivityconcentration,decaycorrectedtothetimeoftheaccident,dividedbyitsactivityasevaluatedinstep1.TEPCOandlaboratoriesthatithascontractedhascarriedofabroadrangeofradionuclide-specificmeasurementsovermanyyearssince2011ofsamplestakenfromdifferentpointsinthecontaminatedwaterprocessingstream.Theseincludelong-lived,high-yieldfissionandneutronactivationproducts,andisotopesofuraniumandtransuranics,includingisotopesofNp,Pu,Am,andCm.Theactivityofeachradionuclideremainingfollowingthestepsabovewasmultipliedbythetransfercoefficientforthegroupinordertoestimateitsmaximumestimatedactivityconcentration.Anyradionuclidehavinganactivityconcentrationlessthan1%oftherespectiveregulatorylimitwaseliminatedfromtheradionuclideinventoriesevaluatedinstep1.Radionuclidesnotassignedtoagroupwereassessedindividually.•Step5:Theremaining37radionuclideswerecategorised:oTritiumtodeterminethedischargeflowrateanddilutionfactor,o29radionuclidestobemeasuredandassessedagainstrespectiveregulatorylimits,plustritium,priortodischargeofeachbatchofALPStreatedwater(sourcemonitoring).oSixradionuclidesthathaveneverbeendetectedbutwillneverthelessberegularlymonitored(butnotforeachbatch).The30radionuclidestobemeasuredandassessed,identifiedbythismethodologyandthesubsequentreviewbyNRA,areshowninTable3.2.Table3.2.RADIONUCLIDESINCLUDEDinTEPCO’sALPSTREATEDWATERSOURCETERM3H79Se125mTe151Sm238Pu14C90Sr129I154Eu239Pu54Mn90Y134Cs155Eu240Pu55Fe99Tc137Cs234U241Pu60Co106Ru144Ce238U241Am63Ni125Sb147Pm237Np244Cm57Thepotentialpresenceofprogeniesinthesourceterm,eventhosewithveryshorthalf-lives,wasassessedbyTEPCOusingthemethodologydescribedabove.ThedecayproductsoftheradionuclidesthatareincludedinthesourcetermaregiveninTable3.3.Mostwereeliminatedatstep4but90Y(2.6dhalf-life,progenyof90Sr)and125mTe(57dhalf-life,progenyof125Sb)werenotandhavebeenincludedbyTEPCOinitssourcemonitoringplan.Accordingtothisplan,levelsofbothradionuclideswillbeassessedthroughmeasurementoftheirrespectiveparentsandassumingequilibrium.Table3.3.DecayproductsoftheradionuclidesincludedinthesourcetermRadionuclideDecayproductHalf-lifeofdecayproductRadionuclideDecayproductHalf-lifeofdecayproduct3Hstable-137Cs137mBa2.6min14Cstable-144Ce144Pr17.3min54Mnstable-147Pm147Sm1.06E11a55Festable-151Smstable-60Costable-154Eustable-63Nistable-155Eustable-79Sestable-234U230Th75400a90Sr90Y2.66d238U234Th24.1d90Ystable-237Np233Pa26.98d99Tcstable-238Pu234U245500a106Ru106Rh30.1s239Pu235U7.03E8a125Sbstable-240Pu236U2.34E7a125mTestable-241Pu241Am432a129Istable-241Am237Np2.1E6a134Csstable-244Cm240Pu6561aTEPCOhasalsoidentifiedadditionalradionuclidesthatwillbemonitoredroutinelytoensureaconservativeapproachisadopted.TheseradionuclideswereexcludedbythemethodologydescribedabovebutarenotsubjecttoremovalbyALPS(withtheexceptionof113mCd)andhavebeendetectedpreviouslyinsamplesofcontaminatedwaterfromFDNPS.Therefore,whileunlikelytobepresentinsignificantquantities,TEPCOnonethelesswillmonitorforthepresenceoftheseradionuclidesonaperiodicbasis(e.g.,noteverybatch).TheseadditionalradionuclidesarelistedinTable3.4.Table3.4.Radionuclidestobemonitoredatintervals36Cl93mNb94Nb93Mo113mCd133BaTheefficiencyofALPSandtheothersystemsdesignedtoreduceactivityconcentrationsofradionuclidesincontaminatedwateratFDNPSisnotconsidereddirectlyatanypointinthismethodologythough,undoubtedly,theactivityconcentrationsofradionuclidestargetedforremovalbyALPSwouldbeexpectedtobelowerfollowingtreatment.Furthermore,theTaskForcenotedthatconsideringtheefficiencyoreffectivenessoftheALPSsystemwasunnecessaryaseverybatchisanalysedforallradionuclidesinthesourceterm(seeTable3.2)plusadditionalradionuclidestoensureaconservativeapproach;therefore,thecontrolforthesystemisnotontheperformanceoftheALPSprocessbutrathera100%verificationofallbatchespriortotheirdischarge.58ThismethodologytocharacterizetheALPStreatedwatersourcetermhasbeenreviewedandapprovedbytheNRA.Someminorchangeswereimplementedbasedonthisreview,forexample55Fe,animportantactivationproductinnuclearwasteintheinitialperiodaftershutdown,which,alongwith129I,14Cand79Se,hasbeenidentifiedintheREIAasanimportantcontributortoingestiondosesforchildrenandinfants(relativelyspeakingconsideringthattheannualcommittedeffectiveingestiondoseisverylowforallagegroups,andlessthan0.04µSvperyear),wasaddedand113mCdand243Cmwereremoved.ThesourcecharacterisationwasfundamentallyrevisedoverthecourseoftheIAEAreview,inpartinresponsetofeedbackfromtheTaskForce.PreviouslytheapproachadoptedbyTEPCOwasoverlyconservativeinanunrealisticmanner–afterconsideringTaskForcefeedback,analternative,appropriatelyconservativeapproachwasadopted.Mostsignificantly,TEPCOchangedtheunderlyingphilosophy,fromidentifyingthe“selectionofradionuclidessubjecttoremovalbyALPS”toselectingthosethatshouldbe“subjecttomeasurementandassessmentwithvigorousverification”.ThisisconsistentwiththerequirementsforcharacterizationofdischargessetoutintherelevantIAEAInternationalSafetyStandards(e.g.,GSG-9para5.20).Thus,thecharacterizationofthesourcedirectlyinformsTEPCO’splanforsourcemonitoringandtheselectionofanalyticalmethodsforeachidentifiedradionuclide(seeSection3.5).NRAprovidedevidencetotheTaskForcethat,fromtheirperspective,nosignificantradionuclideshavebeenexcludedfromthecurrentALPStreatedwatersourceterm.TheevidenceprovidedbytheNRAincludedindependentcalculationsofdosesassociatedwiththeexposurepathwaysusedtosettheregulatoryconcentrationlimitsandexposurepathwaysconsideredintheREIAandcomparisonsoftheresultsofthosetwocalculations.TheTaskForcediscussedwithNRAalternativecharacterizationapproachesthatcouldbeconsideredfordeterminingthesourceterm,ifTEPCOmakesfurtherrevisionsinthefuture.TheexposurepathwayusedtosettheregulatoryconcentrationlimitsbyNRAwasexplainedtotheTaskForceas:“Regulatoryconcentrationlimitisthestandardforthereleaseofradioactivewasteintotheenvironment,whichisspecifiedforeachradionuclideinthe“NotificationEstablishingDoseLimits,etc.BasedontheProvisionsoftheRegulations,etc.ConcerningtheRefiningBusinessofNuclearSourceMaterialorNuclearFuelMaterial.”Itisspecifiedthatifwaterequaltoregulatoryconcentrationlimitiscontinuedtobe[consumed]daily2Lforalifetime(70yearsinadults),themeanexposuredosewillbe1mSv/year.”Furthermore,throughitsownindependentsamplingandanalysisactivities,neithertheIAEA,northeparticipatingthird-partylaboratories,detectedanyadditionalradionuclides(i.e.,radionuclidesbeyondwhatisincludedinthesourceterm)atsignificantlevels.PartIVofthisreporthasadditionalinformationregardingthecurrentresultsoftheIAEA’scorroborationactivities.3.3.3ConclusionsTheIAEAhasconcludedthattheapproachandactivitiesundertakenbyTEPCOandNRAareconsistentwiththerelevantinternationalsafetystandardsincludedunderthissectionofthereport.Furtherdetailedfindingsareincludedbelow:•TheIAEAhasacceptedtherationalepresentedbyTEPCOforasufficientlyconservative,yetrealistic,sourceterm.TEPCO’sapproachincharacterizingthesourcewasatypicalinthatitdidnotusetheradionuclidespotentiallycontributingmosttodoseasastartingpoint.However,asnotedpreviouslyallrelevantradionuclideswerestillincludedandgiventheactivitiesinvolveditisfitforpurpose.59•Theunderlyingphilosophychangedduringtheperiodofitsreview,fromidentifyingthe“selectionofradionuclidessubjecttoremovalbyALPS”toselectingthosethatshouldbe“subjecttomea-surementandassessmentwithvigorousverification”–thisnewapproachisconsistentwiththerequirementsforcharacterizationofdischargessetoutintherelevantIAEAInternationalSafetyStandards(e.g.,GSG-9para5.20).•IAEAnotesthatmanyradionuclidesincludedinthesourcetermwillneverbedetectedinALPStreatedwater.Onlythe“7majorradionuclides”(134Cs,137Cs,60Co,125Sb,106Ru,90Sr,129I)plustritium,14Cand99TccanberoutinelydetectedinsamplesofALPStreatedwater.Therewouldthereforeappeartobeamplescopetorelaxtheconservativismofthesourceterminthefutureasoperationalexperienceisgained.•Theimportanceofmaintainingastrongconnectionbetweenthecharacterizationofthesourceandsourceandenvironmentalmonitoringprogrammeshasalreadybeenstated.Importantinformationwillbecomeavailableasthemonitoringdatabasegrows,whichwillensurethataprioriassumptionscanbeverifiedandthattheREIA,includingthecharacterizationofthesourcecanberefinedasappropriate.3.4.RadiologicalEnvironmentalImpactAssessment3.4.1BackgroundAprospectiveRadiologicalEnvironmentalImpactAssessment(REIA)isanimportanttoolinhelpinglicenseesandregulatorybodiesestimateandcontroltheradiologicaleffectsonthepublicandtheenvironmentfromradioactivedischarges2fromactivitiesandfacilities.AREIAcanservemultiplepurposes,includingestablishingtheinitialbasisforauthorizationwithrespecttotheprotectionofthepublicandtheenvironment,andasanimportantinputintotheprocessofauthorizingcontrolleddischarges.TheaimofaprospectiveREIAistodeterminewhethertheplannedfacilityoractivitycomplieswithcurrentlegislativeandregulatoryrequirementsontheprotectionofthepublicandtheenvironmentunderallreasonablyforeseeablecircumstances.Suchaprospectiveassessmentincludestheconsiderationofexposuresexpectedtooccurinnormaloperationandpotentialexposuresduetoaccidentsthatareidentified.TheREIAshouldbeassimpleaspossible,butascomplexasnecessarytoachievethisaim.GSRPart3[8]setsrequirementsforestablishingagovernmental,legalandregulatoryframeworkforsafetyfortheregulationofactivitiesthatgiverisetoradiationrisks.Theserequirementsareapplicabletoboththeregulatorybodyandregistrantsorlicensees.Theserequirementsincludetheestablishmentofdoselimitsforworkersandthepublic,optimizationofprotectionandsafetyofthepublic,includingdoseconstraintsappliedtopublicexposureinplannedexposuresituations,establishmentofanauthorizationprocess,aswellasrequirementsforoperationalperformance.Theconceptofradiologicalenvironmentalimpactassessmentisincludedaspartofthesafetyassessmentforfacilitiesandactivities.Paragraph3.31ofGSRPart3[8]statesthat:2Adischargeisaplannedandcontrolledreleaseofgaseous,aerosolorliquidradioactivesubstancetotheenvironment60“Safetyassessmentsshallbeconducted…soas:(a)Toidentifythewaysinwhichexposurescouldbeincurred...;(b)Todeterminetheexpectedlikelihoodandmagnitudesofexposuresinnormaloperationsand,totheextentreasonableandpracticable,tomakeanassessmentofpotentialexposures”TheresponsibilitiesplacedontheregistrantsorlicenseeswhenapplyingforanauthorizationfordischargestotheenvironmentaregiveninGSRPart3[8].Paragraph3.9ofGSRPart3[8]statesthat:“Anypersonororganizationapplyingforauthorization:(e)Shall,asrequiredbytheregulatorybody,haveanappropriateprospectiveassessmentmadeforradiologicalenvironmentalimpacts,commensuratewiththeradiationrisksassociatedwiththefacilityoractivity”andparagraph3.15ofGSRPart3[8]statesthat:“Registrantsandlicensees:(d)Shall,forthesourcesforwhichtheyareauthorizedandforwhichtheregulatorybodyrequiresaprospectiveassessmenttobemadeforradiologicalenvironmentalimpacts,conductsuchanassessmentandkeepituptodate;“Aspartoftheprocessoftheauthorizationofdischarges,Paragraph5.43ofGSG-9[9]statesthat,forsettingdischargelimits,theresultsofaprospectiveenvironmentalimpactassessmentconducedinaccordancewiththerequirementsoftheregulatorybodyarerequiredtobeconsidered.GuidanceonREIAforfacilitiesandactivitiesthatshouldbeconductedduringorpriortositing,designandconstructionstagesisgivenininternationalsafetystandardsSeriesNo.GSG-10.Aspartofundertakingaprospectiveassessmentoftheradiologicalenvironmentalimpacts,paragraph3.132ofGSRPart3[8]states:”Registrantsandlicensees,incooperationwithsuppliers,inapplyingforanauthorizationfordischarges,asappropriate:(a)Shalldeterminethecharacteristicsandactivityofthematerialtobedischarged,andthepossiblepointsandmethodsofdischarge;(b)Shalldeterminebyanappropriatepre-operationalstudyallsignificantexposurepathwaysbywhichdischargedradionuclidescouldgiverisetoexposureofmembersofthepublic;(c)Shallassessthedosestotherepresentativepersonduetotheplanneddischarges;(d)Shallconsidertheradiologicalenvironmentalimpactsinanintegratedmannerwithfeaturesofthesystemofprotectionandsafety,asrequiredbytheregulatorybody;(e)Shallsubmittotheregulatorybodythefindingsof(a)–(d)aboveasaninputtotheestablishmentbytheregulatorybody,…ofauthorizedlimitsondischargesandconditionsfor61theirimplementation.”Inapplyingtheprincipleofoptimizationofprotectionandsafetyinthedesign,planning,operatinganddecommissioningofasource,paragraph3.126ofGSRPart3[8]states:“Registrantsandlicensees…,shalltakeintoaccount:(a)Possiblechangesinanyconditionsthatcouldaffectexposureofmembersofthepublic,suchaschangesinthecharacteristicsanduseofthesource,changesinenvironmentaldispersionconditions,changesinexposurepathwaysorchangesinvaluesofparametersusedforthedeterminationoftherepresentativeperson;(c)Possiblebuildupandaccumulationintheenvironmentofradioactivesubstancesfromdischargesduringthelifetimeofthesource;(d)Uncertaintiesintheassessmentofdoses,especiallyuncertaintiesincontributionstodosesifthesourceandtherepresentativepersonareseparatedinspaceorintime.”GSG-9[9]andGSG-10[11]providerecommendationsonundertakingaREIAtomeettherequirementsestablishedinGSRPart3[8].Figure3ofGSG-9(seeSection3.1),showsthestepsintheprocessforauthorizationofdischarges.Thisincludesaprospectiveassessmentofdosestothepublic;suchanassessmentisusuallycalledaRadiologicalEnvironmentalImpactAssessment(REIA).Paragraph5.13ofGSG-9[9]statesthat:“Theregulatorybodyshouldestablishtheprocesstobefollowedbyanapplicantseekinganauthorizationfordischargesoncetheneedforanauthorizationfordischargeshasbeenestablished.Thestepsoftheauthorizationprocessmaybeasfollows:(d)Theapplicantshouldassessthedosestotherepresentativeperson.Thismayinvolveanumberofiterations,startingwithasimple,cautiousgenericassessmentand,ifnecessary,amoredetailed,site-specificstudy.(e)Theapplicantshouldsubmittheresultsoftheassessmenttotheregulatorybody.Theregulatorybodyshouldevaluatewhetherthemodelsandassumptionsusedbytheapplicantareappropriate,shouldcomparetheresultsoftheassessmentwithdoselimitsanddoseconstraints,andshouldevaluatewhethertheassesseddosesareinaccordancewiththeneedtoprovideoptimizedprotectionofthepublic.”GSG-10[11]goesontosay‘Ingeneral,theauthorizationofanuclearfacilitywillrequireahighdegreeofcomplexity,whereforanactivityorfacilityoperatingwithasmallinventoryofradionuclides,asimpleranalysismaybejustified.’Table3.5givesexamplesofthefactorstobeconsideredwhenconsideringthelevelofcomplexityneededforaREIA.GSG-10providesaframeworkforundertakingaREIAandprovidesinformationonthefactorsthatareimportantindeterminingtheneedforandthecomplexityoftheREIAwithinanauthorizationprocess.GSG-10statesthat‘Theapplicantshouldconsiderthesefactorswhensubmittinganapplicationtotheregulatorybodyforreviewandagreement.Forcertainfacilitiesandactivities,thelevelofdetailoftheassessmentcanbedefinedaprioribytheregulatorybody.’62Table3.5.ExamplesofthefactorstobeconsideredwhenconsideringthelevelofcomplexityneededforanREIA(reproductionofFigure1inGSG-10[11]).FactorElementCharacteristicsofthefacilityoractivitySourceterm—Radionuclides—Quantity(bothactivityandmass/volume)—Form(chemical/physicalmake-up)—Geometry(size,shape,heightofrelease)—Potentialforrelease:thesourcetermdifferssignificantlyfornormaloperationandforaccidentsExpecteddosesfromnormaloperationorprojecteddosesfrompotentialexposures—PreliminaryassessmentsorpreviousassessmentsforsimilarfacilitiesSafetycharacteristicsoftheactivityorfacility—Typesofsafetybarrierandengineeringfeaturepresentinthedesign—PotentialforsevereaccidentsCharacteristicsofthelocationCharacteristicsofthefacilitysiterelatingtodispersionofradionuclidesintheenvironment(e.g.geology,hydrology,meteorology,morphology,biophysicalcharacteristics)Presenceandcharacteristicsofreceptors(e.g.demography,livinghabitsandconditions,floraandfauna)ExposurepathwaysLanduseandotheractivities(e.g.agriculture,foodprocessing,otherindustries)Characteristicsofotherinstallationsinthevicinityandpossiblenaturalandhumaninducedexternalevents(e.g.earthquakes,flooding,industrialaccidents,transportaccidents)CharacteristicsoftheauthorizationprocessfortheparticularactivityorfacilityRequirementsorregulations(licensingrequirements)StageoftheauthorizationprocessaThelistprovidedhereisnotexhaustive,andjudgementonthesignificanceofthesefactorswhenselectingthetypeofassessmentwillneedtobemadebyexpertsinnuclearandradiationsafetyintheapplicant’sorganizationandbythenationalregulatorybody.PotentialexposuresUnderRequirement9inGSRPart3[8]ontheresponsibilitiesofregistrantsandlicenseesforprotectionandsafetyinplannedexposuresituations,paragraph3.15states:“Registrantsandlicensees:(e)Shallassessthelikelihoodandmagnitudeofpotentialexposures,theirlikelyconsequencesandthenumberofindividualswhomaybeaffectedbythem…”63ProtectionoftheenvironmentParagraph2.4ofGSG-8[10]expandsonthisrequirementwiththerecommendationthat“Inplannedexposuresituations,exposureatsomelevelcanbeexpectedtooccur.Ifexposureisnotexpectedtooccurwithcertaintybutcouldresultfromananticipatedoperationaloccurrenceoraccidentorowingtoaneventorasequenceofeventsthatmaypotentiallyoccurbutisnotcertaintooccur,thisisreferredtoas‘potentialexposure’.Themagnitudeandextentofpotentialexposurecanusuallybepredicted.Bothexposuresexpectedtooccur,andpotentialexposurescanandshouldbetakenintoaccountattheplanningordesignstage.”TherequirementsonthesystemofprotectionandsafetyinGSRPart3[8]generallyprovideforappropriateprotectionoftheenvironmentfromharmfuleffectsofradiation.Paragraph1.32ofGSRPart3[8]statesthat:“Inaglobalandlongtermperspective,protectionofpeopleandtheenvironmentagainstradiationrisksassociatedwiththeoperationoffacilitiesandtheconductofactivities–andinparticular,protectionagainstsuchrisksthatmaytranscendnationalbordersandmaypersistforlongperiodsoftime–isimportantforachievingequitableandsustainabledevelopment”.Paragraph1.33ofGSRPart3[8]statesthat:“…internationaltrendsinthisfieldshowanincreasingawarenessofthevulnerabilityoftheenvironment.Trendsalsoindicatetheneedtobeabletodemonstrate(ratherthantoassume)thattheenvironmentisbeingprotectedagainsteffectsofindustrialpollutants,includingradionuclides,inawiderrangeofenvironmentalsituations,irrespectiveofanyhumanconnection.Thisisusuallyaccomplishedbymeansofaprospectiveenvironmentalassessmenttoidentifyimpactsontheenvironment,todefinetheappropriatecriteriaforprotectionoftheenvironment,toassesstheimpactsandtocomparetheexpectedresultsoftheavailableoptionsforprotection.Methodsandcriteriaforsuchassessmentsarebeingdevelopedandwillcontinuetoevolve.”Inmanyinstances,itcanbeconcluded,onthebasisofevidencesuchasexperienceorsimplifiedanalysis,thatspecificconsiderationofeffectsintheenvironmentisnotnecessary.Thismaynotbethecaseinallsituations,andtheexplicitconsiderationoftheprotectionoftheenvironmentmayberequiredbytheregulatorybodyanddependsonthecharacteristicsofthefacilityoractivityandtheenvironmentalconditionsunderconsideration(paragraphI-2inGSG-10[11]).Inothercases,explicitconsiderationoftheprotectionoftheenvironmentiscapturedinnationallegislation.Amethodologyfortheexplicitassessmentoftheradiationimpactsonfloraandfauna,whichcanbeusedinaccordancewithnationalorinternationalregulatoryframeworksfortheprotectionoftheenvironment,ispresentedasanexampleinAnnexIofGSG-10[11].Theneedfortheexplicitassessmentoftheprotectionoffloraandfaunaissubjecttothenationalregulations.3.4.2ReviewandAssessmentInlinewiththeBasicPolicyissuedbytheGovernmentofJapaninApril2021,TEPCOundertookaREIA3forthedischargeofALPStreatedwater.Assessmentsofdosestothepublicandtofloraandfaunahavebeenperformed.TheREIAformspartoftheImplementationPlansubmittedtoNRAasitsapplicationforauthorizationofthedischargesofALPStreatedwater.3Unlessotherwisespecified,anyreferencetotheREIAinthissectionreferstothelatestversionsubmittedbyTEPCOinFebruary2023andapprovedbytheNRAinMay2023.64ThereviewoftheREIAwasconsideredwithintheframeworkoftheauthorizationprocessfordischargesdescribedinSection3.1andillustratedinFigure3.1.Thisprocessincludestheapplicant“presentingthemeasurestobeusedfortheoptimizationofprotectionandsafetyofthepublic,havinggivenconsiderationtomeasuresforkeepingtheexposuresaslowasreasonablyachievableandhavingtakenintoaccountallrelevantfactors”asstatedinparagraph5.13inGSG-9.DuringthetwomissionstoTEPCO(seeAnnex1),theTaskForcehelddetaileddiscussionsaboutallaspectsoftheworkundertakenbyTEPCOinproducingtheREIAtosupporttheirapplicationforauthorizationofthedischargeofALPStreatedwater,includingtheresults.FollowingthereviewoftheinitialdraftREIAduringthefirstmissiontoTEPCOinFebruary2022,theTaskForceacknowledgedtheextensiveworkundertakenbyTEPCO.SeveralkeyassumptionsintheREIAregardingthebehaviourofradionuclidesintheenvironmentandtheprospectiveestimatesofthedosetomembersofthepublicwerediscussed.TheTaskForceidentifiedthatamoredetailedandthoroughwrittendescriptionofthemodelling,assumptions,anddatawasneededtoprovideevidencethattheassumptionsmadeareappropriateandsufficientlyconservative.TheTaskForcediscussedwithTEPCOtheimportanceofdocumentingtheirapproachfortheoptimizationofprotection,theparameterstobevariedandthefactorstobeconsidered,andthatTEPCOnoteshowinterestedpartiesareengagedintheprocess.TheTaskForceemphasizedthatTEPCOshouldexplaintheimpactofreducingdoses(topublicandenvironment)onotherfactorsvaluedbyinterestedparties(economic,societalandenvironmentalfactors).TEPCOshouldalsomakeitclearwhytheproposedapproachisoptimalatthispointintime.TheTaskForcenotedthatthisclaritycouldhelpTEPCOwhenengagingwithinterestedpartiesinthefutureandcommunicatingaboutanypotentialchangeswiththedischargeapproach.Itwasdiscussedthatunderstandingtheimpactofvaryingdifferentkeyparameters,suchasthedischargerate,onrelevantfactorsconsideredintheoptimizationofprotectionfortheFDNPSsitewouldhelptoidentifytheoptimalparametersforthedischargeofALPStreatedwaterandthustheoptimaldosetomembersofthepublic.InlinewithSF-1,GSRPart3andGSG-9,theTaskForcerequestedTEPCOtodraftachapterintheREIAdescribingtheoptimizationofprotectioninaqualitativemannerforthedischargeofALPStreatedwater.Thechapterwouldideallyincludeawrittenexplanationofannualdischargesthatmeetthedoseconstraint;optionsforreducingdosebelowthedoseconstraint;andimpactsonotherfactorsfromreducingdoses(topublicandenvironment).TheTaskForcenotedtheoverridingimportanceplacedoncurrentsocietalconcernsintheBasicPolicyforthedischargeofALPStreatedwater.TheTaskForcealsosuggestedthatTEPCOcalculatesandincludesupperlimitsofannualdischarges(correspondingtothedoseconstraint)intheirqualitativedescriptionoftheoptimizationprocess.Inresponse,TEPCOperformedthesecalculationsandshowedthatasignificantlyhigherdischargeratecouldbeusedwhilestillremainingwithinthedoseconstraintestablishedbyNRA.InJuly2022,TEPCOpublishedarevisedREIAthataddressedmanyofthecommentsmadebytheTaskForcebuthadnotyetincorporatedarevisiontothesourcetermwhichwasbeingfurtherdevelopedatthattime(seeSection3.3).InFebruary2023,TEPCOpreparedafinalversionoftheREIAtakingintoaccountanewsourceterm:thisversionalsoaddressedtheadditionalrelevantcommentsmadebytheTaskForceduringthe2ndmissioninNovember2022.TEPCOhasincludedachapterintheREIAthatprovidesadescriptionofoptimizationofprotectionandsafetyinrelationtothedischargeofALPStreatedwater.InFebruary2023,therevisedversionoftheREIAwassubmittedtoNRAaspartofanamendedImplementationPlanandwasapprovedbytheNRAinMay2023.65ApproachadoptedbyTEPCOfortheREIAforthedischargeofALPStreatedwaterFigure3.12summarizesthecomponentsofaREIAforthepublicfornormaloperationofafacilityoractivity.Ingeneralterms,thefirstelementoftheassessmentistocharacterizethesourceofradiationasitrelatestopublicexposure.Next,thedispersionandtransferofradionuclidesintheenvironmentisconsideredtoestimateactivityconcentrationsinfoodandtheenvironment.Dosesareassessedforarepresentativeperson,whoisagenericpersonthatrepresentsthemorehighlyexposedindividualsinthepopulation,takingintoaccountallrelevantpathwaysofradiationexposure.SelectionofthesourcetermModellingofdirectirradiation,dispersionandtransferintheenvironmentAssessmentofthedosetotherepresentativepersonComparisonofestimateddoseswithdoseconstraintsFigure3.12.ComponentsofaREIAforthepublicfornormaloperationofafacilityoractivity(takenfromGSG-10)Thedosetotherepresentativepersoniscomparedwithadoseconstraintforaspecificfacilityoractivity.Thedoseconstraintisusedasastartingpointwithintheprocessofoptimizationandtofindalevelofdischargesthatisoptimalintermsofprotectionofthepublic(asdiscussedinSection3.1).AgenericmethodologyforassessingexposureoffloraandfaunaisprovidedinGSG-10[11]anditisbasedontheICRPapproachfortheprotectionoftheenvironment[12,13].(Figure3.13(fig.I-2ofIAEAGSG-10[11])showsthecomponentsofagenericassessmentforprotectionoffloraandfaunatoillustratetheelementsoftheassessment,theendpointbeingtheassessmentofdoseratestoreferenceanimalsandplantsforcomparisonwithDerivedConsiderationReferenceLevels(DCRL)[12].TheDCRLsdefinebandsofdoserateswithinwhichcertaineffectshavebeennoted,ormightbeexpected,thevaluesarespecifiedinmGyperdaywithaloweranduppervalueforeachreferenceanimalandplant.Asfortheassessmentofdosestothepublic,thebehaviourofradionuclidesintheenvironmentandtheestimationofactivityconcentrationsintheenvironmentareneeded.Inaccordancewiththeconceptofrepresentativeorganisms,thedoseratetobeestimatedintheassessmentoftheimpactonpopulationsoffloraandfaunaisthedoseratethatischaracteristicofthedoseratesreceivedbyagroupofindividualorganismslocatedinareferenceareaaroundthesource,normallyaroundthedischargepoint,wherethehighestexposuresmaytypicallyoccur.Thedoseratecharacteristicsforthisgroupareestimatedusing,forexample,theaverageactivityconcentrationswithinthisreferencearea.GSG-10[11]statesthat“Althoughecologicalcharacteristicsmaydiffer,ingeneral,anareasurroundingthedischargepointoftheorderof100–400km2couldbeusedformostexposurescenariosrelatingtonormaloperationofactivitiesorfacilities”.TEPCOhasusedaseaareaof10x10kmaroundthedischargepointforitscalculationsintheREIA(i.e.,100km2)andtheaverageactivityconcentrationintheseainthisarea.66SelectionofthesourcetermModellingofdispersionandtransferintheenvironmentSelectionofthereferenceanimalsandplantsAssessmentofthedoseratestoreferenceanimalsandplantsComparisonofestimateddosesrateswithderivedconsiderationreferencelevelsFig3.13.Componentsofagenericassessmentforprotectionoffloraandfaunainnormaloperation(takenfromGSG-10[11])Thedoseratestoreferenceanimalsandplants(RAP)arecomparedwithDerivedConsiderationReferenceLevels(DCRL).TheREIA4undertakenbyTEPCOforthedischargeofALPStreatedwaterhasbeenundertakeninlinewiththemethodologydescribedinIAEAGSG-10[11].Assessmentsofdosestothepublicandtofloraandfaunahavebeenperformed.ThemodellingapproachusedintheREIA[15]isnotidenticalbutissimilartothemethodologydescribedinIAEA[26].Asimilargeneric-typemodelisappliedintheREIA.Somesite-specificmodelshavebeenintroduced,inparticularamarinedispersionmodelforthecoastalwatersaroundtheFDNPS,aswellascountry-specificlifestyledata,suchasoccupancyofbeachesandseafoodintakes.Thegeneric-typeapproachinIAEA[25]wasdevelopedsuchthattheestimateddosesaregenerallylikelytobeoverestimated.EachstepoftheREIA[15]performedbyTEPCOisdiscussedinmoredetailbelow.SelectionofasourcetermThefirststepoftheREIAistheselectionofthesourceterm.ThecharacterizationofthesourcetermisdiscussedinSection3.3.ThesourcetermshouldreflecttheradionuclidesthatarereasonablyexpectedtobepresentintheALPStreatedwateratthetimeoftheactualdischarge.AsinputtotheREIA,IAEAinternationalsafetystandardsrecommendthatdischargesbeexpressedintermsofBq/yearforeachradionuclide.TEPCOdescribedtheprocedures,methodologiesandassumptionsusedtoselectthesourcetermsusedintheREIAandtocharacterizethedischarge;thisiscoveredindetailinSection3.3.TEPCOconsidered3sourcetermsbasedonthenuclidecompositionandactivityconcentrationsin3tankgroups,namelyK4(beforeagitationinstallation),J1-CandJ1-G.ThewaterintheK4tankgrouphasbeentreatedbyonetreatmentprocessusingtheperformanceofALPStomakethesumoftheratiostoregulatoryconcentrationslimitslessthan1.Ontheotherhand,thewaterintheJ1-CandJ1-Gtankgroupshavebeentreatedtwicetoreachtherequirementsofthesumoftheratiostotheregulatoryconcentrationlimitbeinglessthan1.Thecompositionsoftheradionuclidesofthethreetankgroupsareconsideredtypicalofthecomposition4Unlessotherwisespecified,anyreferencetotheREIAinthissectionreferstothelatestversionsubmittedbyTEPCOinFebruary2023andapprovedbytheNRAon10May2023.67ofconcentrationsinALPStreatedwater.ThesourcetermcharacterizationisdescribedinmoredetailinSection3.3andintheREIA.ThesourcetermhasbeencalculatedbyTEPCOintermsoftheBqperyearofeachradionuclidedischarged.TherehavebeenseveraliterationsofthesourcetermwhiletheIAEA’ssafetyreviewhasbeenconducted;thisisexpectedandencouragedandisconsistentwithaniterativeapproachasnotedabove.TheTaskForcenotedthatTEPCOshouldassesswhethertherelatedassumptionsintheREIA(i.e.,assumptionsthataredependentonthesourceterm)remainvalidaftereachrevision.TEPCOhasconfirmedthattherevisedsourcetermhasnothadanimpactontheassumptionsmadeintheREIAandthereforetheassumptionsremainvalid.TheTaskForcenotedthatasaconsequenceofrevisingthesourceterminNovember2022,theradionuclidescontributingmosttothedosetothepublicchanged.Inparticular,14Cand129IarenowinthetopthreeradionuclidescontributingmosttotheoveralldosetotherepresentativepersonfromthedischargeoftheALPStreatedwater.Whiletheoverallestimateddosefromthesourcetermremainsextremelylow,TEPCOhasincludedfurtherinformationontheradiologicalimpactof14Cand129IfromthedischargesofALPStreatedwaterandaspecificdiscussiononthebehaviourof14Cand129IintheenvironmentintheREIA.ThisinformationisincludedintheFebruary2023revisionoftheImplementationPlan.BehaviourofreleasedradionuclidesintheaquaticenvironmentThesecondmainstepoftheREIAisthemodellingofdispersionandtransferofradionuclidesintheenvironment.TheREIAprovidesadescriptionofhowTEPCOhasconsideredthetransferoftheradionuclidesreleasedintothemarineenvironment,themodelsandparametervaluesusedandtheassumptionsmadeinthisregard.Importantaspectsofthebehaviourofradionuclidesinthemarineenvironmentaredispersioninthesea,accumulationintheseabedandbeachsedimentsovertheplannedperiodoftheALPStreatedwaterdischarge,andtransfertomarineorganismsandfoods.IntheREIA[15],TEPCOhasusedamarinedispersionmodeltakingintoaccountthemeteorologicalandhydrologicalconditionsinthevicinityofthesite.ThemodeliscalledRegionalOceanModellingSystem(ROMS,www.myroms.org),anditwasvalidatedusingenvironmentalmonitoringmeasurementsforthecaesiumconcentrationsinseawateraftertheFDNPSaccident.Thismodelvalidationisinaccordancewithparagraphs5.2and5.3ofGSG-10[11]thatstatethatthemodelsusedfordispersionandtransferofradionuclidesintheenvironmentshouldbeappropriateforthesituationinwhichtheyarebeingapplied.Themodelsshouldalsobevalidated,whenpossible,comparingtheresultsofmodelcalculationswithactualdataresultingfrommeasurementsforsimilarexposurescenarios.TEPCOusedtheROMSmodeltocalculatetheactivityconcentrationsintheseabasedonthemeteorologicalandoceanographicconditionsin2014and2019.Althoughthereisnolargedifferencebetweentheresultsforthe2years,TEPCOchosetousetheresultsbasedonthe2019dataasthepredictedconcentrationsaroundtheFDNPSwereslightlyhigher.Inrunningthediffusionsimulation,noaccountwastakenofremovalprocesses,suchassedimentation.TEPCOstatesthatthesimulationsofdispersionintheseaweremadefortritium,thencalculationsfortheconcentrationsoftheotherradionuclidesinthesourcetermwereconductedusingtherelativeratiosoftheradionuclidesineachsourcetermconsidered.ThisapproachisbasedontheassumptionthatalltheradionuclidesinthedischargedALPStreatedwaterarewatersolubleandwilldispersetogether.TheTaskForcehadseveraldetaileddiscussionswithTEPCOaboutthemodellingapproachithasadoptedfortheaccumulationofradionuclidesinsedimentsandhowtheactivityconcentrationspredictedareusedtoassessdosestothepublicandfloraandfauna.68Whenradionuclidesarecontinuouslydischargedtothesea,theycanbeabsorbedbysuspendedmatteranddepositedontheseabed.Thisisacontinuousprocessthatcanleadtoanaccumulationofradionuclidesintheseabedsedimentsovertime.Atsomepointtheyaccumulateintheseaenvironmentovertimeuptothepointatwhichequilibriumconditionscanbeassumedbetweentheseawaterandtheseabedsediments(illustratedinFigure3.14).Thetimewhenthisequilibriumwillbeapproachedwilldifferforeachradionuclideandmayoccurshortlyafterthestartofdischargesornotuntilmanyyearslater.Paragraph5.22ofGSG-10[11]explainsthatestimatesofradiationdosesfromthedischargestotheenvironmentshouldbecalculatedforthetimeatwhichthehighestradiationexposureisexpected.Theactivityconcentrationsinenvironmentalmediathatareusedtoestimatetheseradiationdosesneedtoberepresentativeoftheconditionswhenaccumulationcanbeassumedtobeamaximum.Thiswillbethetimewhenequilibriumhasbeenreachedbetweentheseawaterandtheseabedforalltheradionuclidesthataccumulateinseabedsediments.Thisaccumulationinmarinesedimentsisoftenconsideredusingadynamicmodelthatisrunovertheperiodofthedischargesfromanuclearfacilityandthedosefrommarineexposurepathwaysiscalculatedinthelastyearofdischargewhichisconsideredtobethehighestoverthedischargeperiod.However,fortheassessmentoftheradiologicalimpactofaccumulationofradionuclidesinseabedsediments,:TEPCOhasappliedrelativelysimplemodelsintheREIA.Thebuild-upofradionuclidesinsedimentswithtimeisnotexplicitlysimulated;however,theapproachtakenensuresthattheresultingdosesarenotunderestimated.Fortheestimationofactivityconcentrationinsediments,TEPCOhasassumedthatthereisadirectequilibriumbetweenradionuclideconcentrationinseawaterandsedimentsfromthestartofthedischarges,whichisaconservativeassumptionwithrespecttotheassessmentofexternalexposuresfromsediments.AdsorptionanddesorptionequilibriumisreachedBedsedimentWatercolumnSuspendedsedimentRadionuclidesareinthesedimentandalsoinwaterandsuspendedsedimentFig3.14:Behaviourofradionuclidesinseawaterandsediments69TEPCOhasalsobuiltinotherconservativeassumptionsintothedosecalculationsfrommarineexposurepathways.Fordosepathwayslinkeddirectlytoseawater,TEPCOexplainedthatithasbeenassumedthattheconcentrationinseawaterisnotdepletedbytransfertothesediments,anditstaysatthislevelthroughoutthedischargeperiod.Fordosepathwaysrelatingtosediments,TEPCOhasconservativelyassumedthatthereisdynamicequilibriumbetweenseawaterandsedimentsfromthefirstyearthatdischargesstart,eventhoughequilibriumwouldnotactuallybeexpectedtooccurforanumberofyearsafterdischargesstart,asdiscussedabove.Fortheestimationofexternalexposurefrombeachsediments,itisassumedthattheexposureisfroma15cmthicksedimentlayerwithhomogeneousconcentrationsofeachradionuclide.Thisassumptionimpliesthebuild-upofradionuclidesinthesedimentlayerwithtime.Theassumptionofasedimentlayerof15cmensuresthattheexternalexposureisnotunderestimated.Anyradionuclidesatdepthsgreaterthan15cmdonotcontributetotheexternalexposureduetotheshieldingeffectoftheoverlyingsedimentlayers.Insummary,theapproachappliedintheREIAforestimatingexternalexposuresduetooccupancyonbeachsandisconsistentwiththeapproachusedinIAEASRS-19[26].Thedosecalculatedforthefirstyearofdischargeisthereforerepresentativeofthehighestcommittedeffectivedosethatwilloccuroverthedischargeperiod.Bytakingthisconservativeapproach,noassumptionneedstobemadeoftheactualperiodofdischarge.Thedosecalculatedisthecommittedeffectivedosefromexposuresinayear;itiscomparedtothedoseconstraintwhichisalsoexpressedasthecommittedeffectivedosefromexposuresinoneyear.TheapproachtakenbyTEPCOresultsinahighlyconservativeapproachthatislikelytooverestimatetheannualdosesfromboththeconsumptionofseafoodandexternaldosesfrommarinesediments.Therefore,theIAEAnotesthatTEPCOhascalculatedthehighestcommittedeffectivedosethatwouldoccuroverthedischargeperiodassumingthatdischargeswillbereasonablysimilareveryyearandcontinuous.TheapproachadoptedisdescribedindetailintheREIA[25].Aspartofthediscussionsonaccumulationofradionuclidesinsediments,duringthemissionstoTEPCO,theTaskForcehighlightedin-growthofradioactiveprogenyinthesedimentsintheREIA.Anevaluationoftheapproachtakenfortheconsiderationofin-growthofprogenyradionuclidesbyTEPCOisgiveninthetextboxbelow.Insummary,theIAEAconsiderthattheapproachadoptedintheassessmentofdosesofhumansandbiotaintheREIAisappropriate.Whilethiswillnotmakeanynoticeablechangeintheoverallcommittedeffectivedosesgiventheradionuclidesinthedischargesandtheexceedinglylowlevelsofradionuclidesintheseabedsediment,theTaskForcehavesuggestedthatthiscouldbedescribedmoreclearlyintheREIAinthefutureaspartofitsperiodicreview.BehaviourofradioactiveprogenyradionuclidesinthemarineenvironmentSomeradionuclidesinthesourcetermdecaytoradioactiveprogenynuclides(seeSection3.3).TheREIAdoesnotconsiderthetransferofradioactiveprogenynuclidesintheenvironment.However,radioactiveprogenynuclides,ifgenerated,donotcontributeinarelevantwaytotheexposureduringtheperiodofthedischargeofALPStreatedwater.Thiscanbeexplainedasfollows:•Foranyoftheprogenyradionuclidesinthesourcetermwithhalf-livesmuchshorterthanthoseoftheparentradionuclide,suchas90Sr,106Ru,137Cs,144Ce,theenvironmentaltransferisnotrelevantbecausetheprogenyradionuclidesdecayrapidly.However,inthedosecoefficientforestimating70thedosesfromaparticularradionuclide,thecontributionofshort-livedprogenynuclidetotheradiationdoseisproperlyconsidered.•Forlong-livedprogenyradionuclides-suchas147Pm,234U,238U,237Np,238Pu,239Pu,240Pu,241Pu,241Am,244Cm,theingrowthoftheprogenyradionuclidesintoenvironmentalcompartmentsduringthedischargeperiodisnegligible.•Thedosecoefficientsforinhalationandingestionofradionuclidesarecalculatedtotakeaccountofthecommitteddosefromintakesofradionuclidesinayearintegrateduntiltheindividual70yearsold.Duringthistime,theingrowthofradioactivedecayproductsinthehumanbodyiscon-sidered.•Forexample,anadultisassumedtobeage20,forthepurposesofcalculatingdosecoefficients,atthetimeofintakeandthedosecoefficienttakesintoaccounttheradiationdosetothebodyoveraperiodof50years(i.e.,toage70).TEPCOhasusedconcentrationfactorsintheirassessmentoftransfertomarinefoodsintheaquaticenvironmentwhichisaconservativeapproach.Theconcentrationfactorsusedarefrominternationalliterature,inparticular,datacompiledbyIAEA[29]ThisapproachissimilartothatusedinIAEA[26].andiscommonlyusedtoassessactivityconcentrationsinmarinefoodsfromdischargesofradionuclidestotheenvironment.Aspecificactivity5modelprovidesanalternativeestimateunderequilibriumforthelong-livednuclides14Candtritiuminseafood.Inthespecificactivitymodel,thereleaseoftheradionuclideisassumedtoresultinaconstantratiobetweenthereleasedisotopeandthestableisotopeoftheelementintheenvironmentandthebehaviouroftheradionuclideintheenvironmentisassumedtobethesameasthatofthestableisotope.Theconcentrationfactorsusedfor14CandtritiumintheREIA[15]areconsistentwiththeconcentrationspredictedusingaspecificactivitymodel.SpeciationoftritiumintheenvironmentGSG-10paragraph5.9statesthatthe“….physicalproperties…….andchemicalpropertiesrelevantforenvironmentaltransfersanddosimetryofradionuclides”shouldbeselected.Forestimatingthedosestotherepresentativepersonfromingestingtritium,TEPCOinitiallyassumedthatalltritiumisintheformoftritiatedwater(HTO).TheTaskForceadvisedthatitisalsoimportanttoincludetritiuminitsorganicallyboundform(OBT)withrespecttoconsumptionoffood,evenifthedosesfromtritiumarenotanimportantcontributortotheoveralldose.TheTaskForcefurthernotedthatthisislikelytobeatopicofinteresttomanyinterestedpartiesandsuggestedthatTEPCObetterexplainstheuncertaintiesinOBTformationandtheassociateddoses.FollowingthediscussionswiththeTaskForce,TEPCOtookaccountofafractionofOBT(10%)intheenvironmentbasedonICRP56.ICRP56[17]saysthattheexactproportionsofOBTinthevariousmolecularcomponentsofthehumandietareunknownandthereareuncertaintiesassociatedwiththedosesreceivedfollowingtheintakeoftritium.Inordertoaddressthisuncertainty,andwhilerecognizingthatbasedontheresultsoftheREIAtheconsiderationoforganicallyboundtritiumintheestimatesofdosesisunlikelytoimpacttheoveralldosesestimated,theTaskForcehighlightedthatitisimportantthatTEPCOdemonstratesthatithasconsideredthedifferentchemicalformsoftritiumintheenvironmentintheREIA.Followingthesediscussions,TEPCOhasincludedamoredetaileddiscussionofhoworganicallyboundtritiumisaddressedintheREIAandhasincludedtheconservativeassumptionthat100%ofthetritiumin5Thespecificactivityisdefinedastheactivityperunitmassofthecorrespondingstableelement.71consumedfishandseafoodisintheformoforganicallyboundtritium.ThishasnothadanimpactontheestimateddosestothepublicasexplainedfurtherbelowwhentheresultsoftheREIAarepresentedanddiscussed.Forprotectionoffloraandfauna,theICRPapproachdoesnotexplicitlyconsiderthedosefromOBT.ICRP148[18]containsareviewofdatafromstudiesoftherelativebiologicaleffectiveness(RBE)oflow-energybetaparticleemissionsfromtritium.Thereviewofexperimentaldatashowednoclearpatternofdifferencesbetweentritiumspeciesand,forradiationprotectionpurposes,itwasconsideredreasonableonthebasisofcurrentknowledgethatRBEweightedabsorbeddoseratesforRAPsshouldbecalculatedusingvaluesof1foralllow-LETradiationsforcomparisonwiththerelevantDCRL.AcaveatismadeinICRP148[19]that,ifexposurestotritiumbetaparticlesarewithinorclosetotheDCRLband,additionalreviewandpossiblemodificationofRBEweightingmightbewarranted.ThedoseratescalculatedforthemarineRAPsintheREIA(seebelow)areordersofmagnitudebelowtheDCRLs,andsothereisnoneedforadditionalspecificconsiderationsofOBT.TEPCOconsideredtheuncertaintyintheconcentrationofOBTinfishandseafoodintheREIA(AttachmentIIIoftheREIA).TEPCOhasreportedthatinitsmonitoringoffishsince2014aroundtheFukushimaDaiichiNuclearPowerStation,OBThasneverbeenobservedinthe83samplesmeasuredsofar.TEPCOalsoreferstomonitoringoftheconcentrationratiobetweenHTOandOBTintheenvironmentaroundtheLaHaguereprocessingplantinFrancewhichisthesamefortheseafoodspeciesmeasured,includingfishandseaweed.AdditionalinformationontritiumandhowitbehavesintheenvironmentisprovidedinAnnex5.IdentificationofExposurePathwaysThenextstepintheREIAistheidentificationofexposurepathwaysandthechoiceoftherepresentativepersonforwhomthedosesareestimated.ThemaintransferprocessesinthemarineenvironmentandexposurepathwaysforhumansareillustratedinFigure3.15.DischargeDispersionintheoceanSedimentationAquaticfoodsSeasprayinhalationExternalirradiationHabitsegbeachoccupancyAquaticfoodintakesIndividualdoseMainExposurePathwaysFig.3.15.IllustrationofmaintransferprocessesandexposurepathwaysforhumansinthemarineenvironmentInaREIA,theexposurepathwaysthatareconsideredrelevantfordischargestotheenvironmentforaparticularscenarioandtherelativeimportanceofdifferentexposurepathwaysshouldbeidentified.In72thecaseofdischargestothesea,considerationneedstobegiventotheexposurepathwaysarisingfromusesoftheseawater,suchasproductionofaquaticfoods,fishingindustriesandrecreation(paragraph5.27ofGSG-10[11]).Inparagraph5.30ofGSG-10[11],itisexplainedthat,dependingontheexposurescenariosandthesitecharacteristics,notallthepossibleexposurepathwaysmayneedtobeincludedintheassessmentbecausethecontributionofanexposurepathwaytotheoveralldosedependsontheradionuclidesinvolved,thehabitdata,thetimespentatalocationandothercharacteristicsofthepopulationbeingconsidered.Therefore,someexposurepathwaysmaybeexcludedfromtheassessmentonthegroundsthatthedosesassociatedwiththemareevaluatedtobenon-existentornegligible.However,paragraph5.30inGSG-10[11]clarifiesthatthedecisiontoexcludeparticularexposurepathwaysfromconsiderationshouldbejustified.IntheREIApresentedbyTEPCO,anumberofinternalandexternalexposurepathwayswereinitiallyidentifiedasrelevantfortheALPStreatedwaterdischargestothesea.DuringthefirstmissiontoTEPCO,theTaskForcenotedthatalthoughthedominantexposurepathwayisexpectedtobeingestionofseafood,itisgoodpracticetodemonstrateintheREIAthatallplausibleexposurepathwayshavebeenconsidered,evenifthedosesareexpectedtobeverylow.Thisisnecessarytojustifyexcludingexposurepathwaysthatmakeaminorcontributiontothedoses.TheTaskForceidentifiedtheminorexposurepathwaysofinhalationofresuspendedmaterials(e.g.,sea-spray,beachsediments),betadosestotheskinfromhandlingfishingnetsandinadvertentingestionofsediments,thatcouldbeconsideredforcompleteness.FollowingthediscussionswiththeTaskForce,TEPCOincludedotherminorexposurepathwaysinaccordancewithGSG-10[11]andconsideredotherpotentialexposurepathwayslistedinothernationalorinternationalguidelines.ThelistofexposurepathwaysconsideredintheREIAisgiveninTable3.6.TEPCOhasdocumenteditsassessmentofthedosesfromtheminorexposurepathwaysintheFebruary2023versionoftheREIAforcompleteness;apresentationanddiscussionoftheresultsisgivenlaterinthisSection.TABLE3.6.EXPOSUREPATHWAYSCONSIDEREDBYTEPCOINTHEREIA(majorexposurepathwaysinbold)ExternalexposurepathwaysInternalexposurepathwaysExternalexposurereceivedfrom:•Seasurface•Hullofship•Immersioninwater(swimming)•Beachsediments•FishingnetsIngestionofseafood(fish,molluscsandsea-weed)Inadvertentingestionofseawaterwhileswim-mingInhalationofseasprayAssessmentofthedosetotheRepresentativePersonHavingidentifiedthepathwaysbywhichapersoncanbeexposedtoradionuclidesintheenvironmentfollowingthedischargestosea,thenextstepintheREIAistoassessthedosestotherepresentativeperson.Therepresentativepersonisselectedtohavethecharacteristicsofindividualswhoarelikelytobemorehighlyexposed.Animportantcharacteristicwhenassessingdosestotherepresentativepersonistheassumedlocationoftherepresentativeperson(e.g.,hisorherdistanceanddirectionfromthepointofdischargeofradionuclides)asdescribedinparagraph5.34ofGSG-10[11].Thelocationwheretherepresentativepersonlivescanbebasedonanactualpersonoragroupofpersons,oronapostulatedpersonorgroupofpersonslivingatalocationselectedusingcautiousassumptions(e.g.,atapointwherethehighestconcentrationsintheareacanbeexpected).73TEPCOstatedintheREIAreportthatthecharacteristicsoftherepresentativepersonweresetinaccordancewith“Publicdoseassessmentguidelineforsafetyreviewofnuclearpowerlightwaterreactor”.Habitdata,suchasconsumptionratesoffoodfortherepresentativeperson,usedintheassessmentwerebasedonnationalstatisticaldatasets(NationalHealthandNutritionSurveyinJapan).Table3.7summarizesthecharacteristicsoftherepresentativepersonasdescribedbyTEPCOintheREIAreport.TEPCOconsideredthehabitsofthreeagegroups;adults,childrenandinfantsintheassessmentofdosesintheREIA.TABLE3.7.HABITDATAUSEDINTHEREIA[17]BYTEPCOFORTHEREPRESENTATIVEPERSONParameterAdultChildInfantIngestionrates[gd-1]aFish58(190)b29(97)12(39)Invertebrate10(62)5.1(31)2(12)Seaweed11(52)5.3(26)2.1(10)Occupanciesfortherepresentativeperson[hry-1]Beach500Fishing2880Handlingfishingnets1920Swimming96aIngestionratesofseafoodfortherepresentativepersonarebasedonnationalstatisticaldatasetsforJapan.bTwoscenarioswereconsideredintheassessment:oneforapersonwhoingestsseafoodattheaveragevaluesandtheotherforapersonwhoingestsalargeamountofseafood(mean+2σ).Forestimatingdosestotherepresentativepersonfromalltheexposurepathwaysconsidered,TEPCOusedthemarinedispersionmodeltocalculateactivityconcentrationsinseawaterina10kmx10kmareaaroundthedischargepoint(seeFig.3.16).Theseactivityconcentrationsinseawaterwereusedasthebasisforallthedosescalculatedfortherepresentativeperson.TheTaskForcediscussedwithTEPCOwhethertheaverageconcentrationusedisconservativegiventhehigherconcentrationsintheseapredictedusingthemarinedispersionmodelalongthecoastduetotheseacurrentsbothwithinthe‘difficulttoreturnzone’andjustoutsideit.ThesehigherconcentrationsintheseaweretakenintoconsiderationinthefurtheriterationsoftheREIAwithrespecttoidentifyinginmoredetailthecharacteristicsandlocationoftherepresentativeperson.Inparticular,theTaskForcediscussedwithTEPCOthatnoaccountwasbeingtakenofmembersofthepublicusinglocalbeachesforrecreationalpurposes.TEPCOexplainedthatthiswasaconservativeassumptionasmembersofthepubliccannotliveorundertakeactivitiesclosetothecoastlinewithinthe‘difficulttoreturnzone’orthe‘noclaimforfishingzone’;howeverTEPCOalsorecognizedthatwhilsttherearecurrentlynoinhabitants3kmnorthofthesite,therepresentativepersoncouldtraveltothebeach.TEPCOsubsequentlyusedthislocation(3kmnorthofthesite)tocalculateexternaldosesintherevisedversionsoftheREIA(seeFig.3.16).Additionally,TEPCOrecognizedthatindividualscouldalsocatchasmallproportionoftheirfishandseafoodconsumptionfromlocalbeachesatsomepointinthefutureandincludedascopingcalculationintheREIAtoincludethis.Thecalculationindicatedthatthedosetoanadultfromingestionoffishandseafoodcouldincreasebyabout20%if10%oftheirconsumptionwascaughtlocally.74UkedoportDifficult-to-ReturnZonesInterimstoragefacilitysitePointofdischargeAreawherefishingisnotroutinelyconducted10kmby10kmrangeofthestationAssessmentpointforexposureduringswimming,frombeachsand,fromingestionofwater,andfrominhalationofseawaterspray10km10kmAssessmentareaforexposurefromseasurface,fromhulls,fromfishingnet,andfromingestionofseafoodFig3.16.LocationoftherepresentativepersonfornormaloperationofdischargeofALPStreatedwaterintheREIA(takenfromTEPCO[15])Paragraph5.36ofGSG-10[11]explainsthattheindividualeffectivedosetotherepresentativepersonisthesumofthecommittedeffectivedosefromintakesofradionuclides(i.e.,frominternalexposurebyingestionandinhalation)andtheeffectivedosefromexternalexposure.Dosesfrominternalexposurearecalculatedusingdosecoefficientsfromintakesofradionuclidesbyingestionandinhalation,whichprovidethecommittedeffectivedoseperunitactivityofintake,expressedinunitsofsievertsperbecquerel(Sv/Bq).TabulatedvaluesofdosecoefficientsapplicableformembersofthepublicareavailableinGSRPart3[8].Standardmodelsexisttocalculatetheeffectivedosefromexternalexposure,aswellascompilationsofdosecoefficients.Thecommittedeffectivedose(calculatedfortherepresentativeperson)isanannualdose.Thisannualdoseiscomparedwiththedoseconstraintof0.05mSvperyear.Asdiscussedabove,theannualcommittedeffectivedosecalculatedintheREIA,isthehighestannualdosethatcouldbeexpectedovertheperiodofthedischarges.Assumingthatthisdoseisreceivedannuallyovertheperiodofthedischargesisthereforeaconservativeassessment.AssessmentofdosestofloraandfaunaandendpointsThegenericmethodologyforassessingexposureoffloraandfaunabasedontheICRPapproachinGSG-10[11]usesrepresentativeorganismsselecteddirectlyfromtheICRPreferenceanimalsandplants[12;13].Theserepresentativeorganismsareselectedtobethoserelevantforthespecificmajorecosystem(e.g.,terrestrial,marine,freshwater)assumedtobelocatedintheareawheretheexposureconditionsleadtothehighestdoses.TheICRPapproachusestheconceptofreferenceplantsandanimals[12].TheICRPdefinesthreespeciestobeusedasreferencesfortheprotectionofthemarineenvironment.Theconceptualapproachisthat,75ifthecriteriaforthosethreereferencespeciesisnotexceeded,thenallthespeciescanbeassumedtobeequallywellprotected,attheleveloftheirpopulations(particularlyforplannedexposuresituation).Thethreespecieswereidentifiedbasedontheirwideglobaldistributionandtheexistenceofactualdataontheeffectsofverylowincrementsofradiationdoses(incrementscomparablewiththevariationofnaturalradiationindifferentscenarios).TEPCOhascalculateddoseratesforthethreereferencemarinespeciesinICRP,namelyflatfish,crabandbrownseaweed.Figure3.17showstheexposurepathwaysandthecalculationundertakentocalculatedoserates(mGyperdayforthe3representativemarineorganisms).DoseCoefficientsSourceofRadionuclidesActivityconcentrationsinRAPs(flatfish,crab&brownseaweed)DoseratesinRAPsExposurePathways:Ingestion:seawater&sedimentExternalexposure:seawater&sedimentTransferintheMarineEnvironmentFigure3.17.Exposurepathwaysandassessmentofdose(mGy/day)ratestofloraandfaunaintheREIATheexposurepathwaysconsidered,inlinewiththeapproachdescribedinGSG-10were:•Internalexposurefromradioactivematerialsingestedbyanimalsorabsorbedbyplants•Externalexposurefromthesurroundingseawater•ExternalexposurefromthesurroundingseabedsedimentsResultsoftheREIATEPCOhaspresentedtheannualcommittedeffectivedosescalculatedintheREIAtotherepresentativepersonforthedifferentexposurepathwaysanddifferentagegroupsconsidered.Theagegroupsanddosecoefficientsusedforcalculatingcommittedeffectivedosesforadults,children,andinfantswereinaccordancewiththoseprovidedinGSRPart3[8].76ADULTTotaldose=0.008µSvExternal8.1%Internal91.9%Ingestionofwater4.6%Inhalationseaspray1.3%Ingestionseafood94.1%CHILDTotaldose=0.009µSvExternal7.1%Internal92.9%Ingestionofwater6.9%Inhalationseaspray0.7%Ingestionseafood92.4%INFANTTotaldose=0.008µSvExternal8.5%Internal91.5%Ingestionofwater0.0%Inhalationseaspray0.7%Ingestionseafood99.4%Figure3.18:Contributionofexposurepathwaytothecommittedeffectivedoseforhighseafoodconsumersasafunctionofagegroup(K4ALPStreatedwatertankgroup)Figure3.18showsthecontributionofexposurepathwaystothecommittedeffectivedoseforhighseafoodconsumersasafunctionofagegroup.TheFigureshowsthatthecontributionfrominternalexposurecontributesabout90%ofthetotaldoseforallagegroupsandthattheingestionofseafoodcontributesbetween92%and99%oftheinternaldose.Figure3.19presentsinformationforthecommittedeffectivedosescalculatedasafunctionofageandmainexposurepathwaysbasedonthesourcetermfortheK4ALPStreatedwatertankgroup.Theresultsfortheothertwotankgroupsconsideredareverysimilar.770,0000000,0000050,0000100,0000150,0000200,0000250,0000300,0000350,000040TotalInternalExternalTotalInternalExternalTotalInternalExternalADULTCHILDINFANTmSvperyearFigure3.19:Committedeffectivedoseasafunctionofageandexposurepathway(K4ALPStreatedwatertankgroup)Table3.8alsoshowsthattheannualcommittedeffectivedoseissimilaracrossthethreeALPStreatedwatertankgroupsourcetermsforadults.Table3.8showsthattherelativecontributionsoftheradionuclidestotheingestiondosevariesbetweenthethreesourcetermsbutinallcasesthedosesareverylowandmorethan1000timeslowerthanthedoseconstraintof0.05mSvperyear.Carbon-14,129Iand55Fearethelargestcontributorstotheinternaldoseandthetotaldose.Thisisalsothecaseforchildrenandinfants.Tritiumtypicallycontributesnomorethanafewpercentofthetotalcommittedeffectivedose.Thehighestcontributionfromtritiumisfromtheinadvertentingestionofseawaterwhileswimming(adultsandchildren);itisnotedthatTEPCOassumesaconservativeconsumptionrateof0.2l/hofseawaterwhileswimming.AgegroupSeafoodintakeStoragetankDose(mSv/y)StoragetankDose(mSv/y)StoragetankDose(mSv/y)K4J1-CJ1-GAdultsHigh129I1.8E-05129I2.0E-0614C4.4E-0614C7.1E-0614C1.6E-0655F2.5E-0655F3.8E-0655F8.5E-07129I1.6E-0679Se1.6E-063H5.0E-0779Se9.5E-0760Co5.8E-0779Se3.2E-073H5.0E-073H5.0E-0760Co1.2E-07240Pu3.0E-07137Cs1.8E-07240Pu1.2E-07239Pu3.0E-0799Tc1.1E-07239Pu1.2E-07241Am2.8E-07125Sb2.8E-08241Am1.1E-07238Pu2.7E-07155Eu2.7E-08238Pu1.1E-0760Co2.6E-07Allothers1.2E-07Allothers3.6E-07Allothers8.9E-07Total3.2E-05Total6.2E-06Total1.2E-05Table3.8.AnnualcommittedeffectivedoseforanadulthighseafoodconsumersasafunctionofradionuclideandALPStreatedwatertankgroup78Asdiscussedabove,theingestionofseafoodisthehighestcontributiontothecommittedeffectivedoseforallagegroupsandforthethreeALPStreatedwatersourcetermsconsideredintheREIA.Figure3.20showstherelativecontributionsofradionuclidestotheingestiondoseforallthreeagegroupsforahighseafoodconsumer.TheFigureshowsthattheradionuclidescontributingmosttotheingestiondoseare129I,14C,55Feand79Sewhichcontributeover90%ofthedose.Fe-55and79Searerelativelymoreimportantforchildrenandinfantsduetothehigherdosecoefficients(SvperBqofintake).ItisnotedthatTEPCOhasnotdetected55Feand79SeintheALPStreatedwaterandtheestimatedcommittedeffectivedosesarebasedonlevelsoftheseradionuclidesinthedischargebeingatthedetectionlimitsfortheanalyticaltechniqueused.ItisnotexpectedthattheseradionuclideswillbedetectedintheenvironmentandinseafoodbuttheyareincludedintheCRMP(seeSection3.5).However,itshouldbestressedthattheannualcommittedeffectiveingestiondoseisstillverylowforallagegroups,andlessthan0.04µSvperyear.Totaladultingestiondose=0.03µSvI-129TotalChildIngestiondose=0.04µSvTotalInfantIngestionDose=0.03µSv129I129I129I14C14C14C55Fe55Fe55Fe79Se79Se79Se60Co60Co99Tc137Cs60CoTritiumTritiumOthersOthersOthersFigure3.20.Committedeffectivedosefromingestionforhighseafoodconsumerasafunctionofagegroup:percentagecontributionofradionuclides(K4tankgroup)79Figure3.21showstheradionuclidecontributiontotheannualexternaldosefortherepresentativeperson.TheexternaldoseisthesumoveralltheexternalexposurepathwaysconsideredintheREIAbutisdominatedbytheexposuretooccupancyonthebeach(about85%fortheradionuclidescontributingmosttotheexternaldose).Theexternaldoseisonlycalculatedforanadult,asitisassumedthatchildrenonlyspendtimeonthebeachwhenaccompaniedbyadultsandthatthereisnosignificantdifferenceintheeffectiveexternaldosereceivedbythedifferentagegroups.Figure3.21showsthatthetworadionuclidescontributingmosttotheeffectiveexternaldoseare60Coand137Cs.60Co155Eu137Cs154Eu241Pu134Cs125Sb106RuAllothers34.5%24.4%15.7%8.3%7.4%4.0%2.6%1.7%1.4%60Co155Eu154Eu241Pu137Cs106Ru134Cs125SbAllothers34.8%34.8%6.6%6.5%6.2%3.5%3.1%3.0%1.4%Adult(J1-Ctankgroup)Totalexternaldose=0.002µSvAdult(J1-Gtankgroup)Totalexternaldose=0.0005µSv60Co137Cs155Eu125Sb121I134Cs154Eu106RuAllothers60.8%25.5%4.1%4.1%1.5%1.3%1.0%1.0%0.5%Adult(K4tankgroup)Totalexternaldose=0.002µSvFigure3.21.EffectiveexternaldoseasafunctionofradionuclideandALPStreatedwatertankgroup(theexternaldoseisassumedtobethesameforallagegroupsintheREIA)ThedosestomembersofthepublicestimatedintheREIAasaresultofdischargesofALPStreatedwateraremorethan1000timeslowerthanthedoseconstraintsetbyNRAof0.05mSv/y.Subsequently,usingtheapproachofagenericmethodologyinconjunctionwithsite-specifichabitdataisinlinewiththeguidanceinGSG-10[11]andthereisnoneedtorefinethedoseassessmentwithmorecomplexmodelsandsite-specificparametervaluesonradiologicalprotectiongrounds.However,toaddresstheinternationalinterestintheradiologicalimpactoftheproposeddischarges,intheREIAundertakenbyTEPCO,asite-specificmarinedispersionmodelandafullrangeofexposurepathwayshasalreadybeenconsidered.TheREIAalsocontainsanassessmentofdosestofloraandfaunausingtheapproachgiveninGSG-10[11],whichisin-linewiththeICRPapproach[12;13].ThehighestdoseratestofloraandfaunaovertheperiodofdischargesofALPStreatedwaterareestimatedbyTEPCOtobe<110-6mGyperday(0.000001mGyperday).Thecalculateddoseratestothethreereferenceorganisms(flatfish,crabsandseaweed)aremorethanamilliontimeslowerthatthelowestderivedconsiderationreferencelevel(DCRL)of1mGyperday,whichisforflatfish.80TransboundaryimpactsoftheALPStreatedwaterdischargeInparagraph5.24ofGSG-9[9]itisidentifiedthatifadischargecouldcausesignificantpublicexposureoutsidetheterritoryorotherareaunderthejurisdictionorcontroloftheStateinwhichthedischargetakesplace,theoperatingorganizationshouldmakeanassessmentoftheradiologicalimpactsofthedischargesonthepublicandtheenvironmentintheseareas.TheTaskForcediscussedwithTEPCOthatthereareradionuclidesinthesourcetermthatcouldhaveanimpactforglobalcirculationintheoceans(e.g.,129I,14C,99Tc,3H)andthat,eventhoughdosesfromglobaldispersionandcirculationintheoceansarelikelytobeverysmall,oreffectivelyzero,dosestoneighbouringcountriesfromglobalcirculationareofinteresttotheinternationalcommunity.Therefore,thistopicshouldbeconsideredandexplainedintheREIA.TEPCOnotedthattheflowofseacurrentswastakenintoaccountwithinthemodelandtheestimatedactivityconcentrationsoftritiumintheoceanwerelowand,thatitwouldbedifficult,orimpossible,todetecttritiumfromtheALPStreatedwateratlargedistancesfromthepointofdischarge.TheTaskForcenotedthatthecalculationalareaofsimulationsforthemarinedispersionmodelis490kmnorth-southand270kmeast-westandhadencouragedTEPCOtouselongerdistancedispersioncalculationstoshowclearlythatdosestoneighbouringcountriesarenegligible.TEPCOexplainedthatbasedonmeteorologicalandoceanographicconditionsovera7-yearperiodfrom2014to2020,themarinedispersionmodelpredictsverylowconcentrationsoftritiumthatwillbeundetectableattheboundaryofthesimulationarea(490kmnorth-southand270kmeast-westoftheFDNPS);therefore,extendingtherangeoftheexistingmodelboundarywouldnotaddanytechnicalvalueforassessmentoftheradiologicalimpactoftheALPStreatedwaterdischarges.TheTaskForceacceptedTEPCO’sreasoningthatconcentrationsoftritiumbeyondthisareawillbeevenlowerandthereforethereisnoscientificjustificationforredoingthecalculationsforalargerarea.TheTaskForcerecommendedthatincludingestimatesofactivityconcentrationsof14Cand129Iinseawaterattheboundaryofthesimulationareacouldalsodemonstratethattheconcentrationsoftheseradionuclidesarenegligibleandthatthiswouldprovideausefulcomparisonforcommunicationwithinterestedparties.TEPCOaddedthisintotherevisedREIAinresponsetotheTaskForces’views.TEPCOalsostatedintheREIAthattheyearlyradioactivedischargeof14Cand129IfromALPStreatedwaterisaverysmallamount,thereforeitsimpactatglobalscaleisnegligible.BasedontheresultsofthemarinedispersionmodelusedbyTEPCO,activityconcentrationsininternationalwaterswillnotbeinfluencedbythedischargeofALPStreatedwaterintotheseaandthetransboundaryimpactsarethereforenegligible.However,thebaselineenvironmentalmonitoringinplacearoundtheFDNPSandinthesurroundingareaofthePacificOcean,aswellasthatplannedbyTEPCOandtheGovernmentofJapanafterthestartofdischarges(seeSection3.5)isextremelyimportanttoascertainanylevelsofradionuclidesintheseaduetothedischargeofALPStreatedwaterandtoverifythefindingsoftheREIA.TEPCOstatedintheREIAthattheyearlyradioactivedischargeof14Cand129IfromALPStreatedwaterisaverysmallamount,thereforeitsimpactatglobalscaleisnegligible.TEPCOpredictionsofactivityconcentrationsoftritiuminthePacificOceanIntheREIAsubmittedbyTEPCO,theestimatedactivityconcentrationsintheoceanbasedonthemarinedispersionmodelshowthat:81•Estimatedtritiumconcentrationsofseawaterabove1Bq/Lislimitedtoanareaofupto3kmaroundFDNPS.•Theestimatedaveragetritiumconcentrationsforthearea10kmx10kmforallwaterlayersis0.056Bq/Land0.12Bq/Lforthesurfacelayer.Forestimatingexposuresduetooccupancyonthebeachandfrominhalationofseaspray,theunderlyingtritiumactivityconcentrationinwateris0.88Bq/L.Thesimulatedtritiumactivityconcentrationattheeasternboundaryofthesimulationareaisbetween0.0001and0.0003Bq/L.Forcomparison,theaverageH-3concentrationintheNorthPacificOceanbetweenlatitudes30Nand45Nisabout0.04Bq/L1andbackgroundactivityconcentrationsintheseaaroundtheFDNPSareintherangeof0.1–1.0Bq/l.ThismeansthatthetritiumconcentrationintheseafromthedischargeofALPStreatedwaterattheboundaryofJapaneseterritorialwaterswillalreadybelowerthanthebackgroundconcentrationoftritiumintheNorthPacificbetweenlatitudes30Nand45N.1.Oms,P.E.,BaillyDuBois,P.,Dumas,F.,Lazure,P.,Morillon,M.,Voiseux,C.,LeCorre,C.,Cossonnet,C.,Solier,l.,Morin,P.:Inventoryanddistributionoftritiumintheoceansin2016.ScienceoftheTotalEnvironment,Elsevier,2019,656,pp.1289-1303.‌10.1016/j.scitotenv.2018.11.448‌.‌hal-02336283‌AssessmentofdosesfrompotentialexposuresAspartofthesafetyassessmentforfacilitiesandactivities,varioustypesofaccidentarepostulatedtoidentifyengineeredsafetyfeaturesandoperationalactionstoreducetheirlikelihoodand,ifanaccidentdoesoccur,tomitigateitsconsequences(paragraph5.44ofGSG-10[11]).InaccordancewiththerecommendationsprovidedinGSG-10[11],aprospectiveassessmentofpotentialexposurestomembersofthepublicshouldbeperformedforexposurescenariosresultingfrompostulatedaccidentsidentifiedonthebasisofthesafetyassessment.Therepresentativepersonforpotentialexposuresneedstobeidentified,notingthattherepresentativepersonmaynotbethesameasthatselectedfornormaloperations,andanassessmentofthedosetotherepresentativepersonestimatedandcomparedwiththeapplicableestablisheddosecriteria.TEPCOhasincludedintheREIA[15]anassessmentofthepotentialdosestoarepresentativepersonfromtwoidentifiedaccidentscenariosaffectingthedischargeofALPStreatedwater.Theseare:Case1–LeakagefrompipingInthisscenario,TEPCOassumedthataleakagefromapipeoccurredthatcausedundiluted,treatedwater,toflowdirectlyintothesea.Whilecountermeasuresareinplacetodetectanincidentofthisnaturewithin24hoursorless,itisassumedthatthisscenariocontinuedundetectedover20daysresultinginthelossofanentiretankgroup(10tanksintotal),oraround10,000m3oftreatedwater.Case2–LeakagefromtanksInthisscenario,TEPCOassumedaworst-caseaccidentwheretherewasacatastrophicandimmediateruptureofalltanksinthemeasurementandconfirmationfacilitywhichresultedinallofthetreatedwaterbeingdischargeddirectlyintotheseawithoutanyfurtherdilution.Thisworst-casescenariowouldresultinallthreetankgroups(30tanksintotal),around30,000m3oftreatedwater,beingdirectlydischargedintotheseawithoutdilution.TEPCOhasusedadosecriterionof5mSv/yearinlinewiththerecommendationsinGSG-10[11].TheTaskForcediscussedtheassumptionsmadebyTEPCOinitsinitialcalculationoftheimpactofthesepotentialexposurescenarios.ItwasagreedthatitisimportanttocalculatethedosesfromallexposurepathwaysandtothethreeagegroupsconsideredintheREIA(adults,childrenandinfants),82withoutconsiderationofprotectivemeasuresormitigationmeasuresthatcouldbeimplementedifsuchanaccidentoccurred.Inparticular,theTaskForceemphasizedthattheREIAneedstoincludemarinefoodconsumption,evenifitisexpectedthatmarineproductsintherestrictedzonewouldinpracticebebanned,andallradionuclidesinthepotentialsourcetermneedtobeconsideredorrepresentedintherelevantcalculations.TEPCOstatedthattherepresentativepersonforthepotentialexposureassessmentisanadultfishermanwhoconsumesalargeamountofseafood;thelocationusedforallexposurepathwaysisfrom3kmnorthofthesite.Inaddition,potentialdosesfrominternalexposurepathwaysforchildrenandinfantshavebeencalculated(inhalationofseaspray,ingestionofseafoodandinadvertentingestionofwater(childrenonly)).Theexposuretimesassumedfortheadultfisherman(representativeperson)isgiveninTable3.9.Table3.9.Exposuretimesusedfortherepresentativepersonfortheassessmentofpotentialexposures(takenfromREIA)ItemCase1(27days)Case2(8days)Operationhoursonaship210hours63hoursSwimmingtime7.1hours2.1hoursCoastlinestaytime37hours11hoursOperationhoursnearfishingnets140hours42hoursIngestionofseafoodIngestionofpersonswhoconsumealargeamountofseafoodin27daysIngestionofpersonwhoconsumealargeamountofseafoodin8daysForpotentialexposures,GSG-10[11]statesthattheeffectivedoseresultingfromthesumofthecommittedeffectivedosefrominternalexposurepathwaysandtheeffectivedosefromexternalexposureshouldbecalculated.However,italsostatesthattheequivalentdosetocertainorgans(e.g.,thyroid)canbeconsidered;theTaskForcesuggestedthatTEPCOcouldclarifythatithadconsideredequivalentdosesintheREIA.TEPCOexplainedthat,althoughahigherconcentrationofradionuclideswouldbereleasedintheeventofanaccident,theradionuclidesarethesameandthebehaviourintheenvironmentandexposurepathwaysarethesame.TEPCOstatedthatthepredictedeffectivedosesareverylow,includingthehighestdosefrom129I(approx.0.01mSvforCase2)andthattheassessmentofequivalentdose(e.g.,tothethyroidforinfants)isnotneededattheseverylowlevelsofeffectivedose.TherangeofpotentialcommittedeffectivedosescalculatedfortherepresentativepersonforCase1(pipingrupture)consideringthethreetankgroups(K4,J1-CandJ1-G)is0.0002-0.0003mSv.ForCase2(tankdamage)therangeofpotentialcommittedeffectivedosesis0.008-0.01mSv.Theonlysignificantexposurepathwayforallagegroupsistheingestionofseafoodwhichcontributesmorethan99%ofthecommittedeffectivedose.Thedosesforchildrenandinfantsareslightlyhigherthanthoseforadultsbutforbothaccidentcasesarelessthan0.02mSv.ConsiderationofUncertaintiesandSensitivityanalysisInChapter8oftheREIA,varioussourcesofuncertaintiesareconsideredandthepossibleimpactontheresultsisestimated.TEPCOhasconsideredthefollowingitemsintheREIAaspartoftheirassessmentofuncertainties.Detailsoftheuncertainty,asdescribedbyTEPCO,aregiveninparentheses.•Selectionofthesourceterms(ThecompositionofradionuclidesofALPStreatedwaterisunknownuntilsecondarytreatmentandmeasurementiscompleted.Thereisuncertaintyassociatedwiththemeasuredvalues).83•Modellingofdiffusionandtransferintheenvironment.(Themeteorologicalandoceanographicdatahasannualvariations.Thereisuncertaintyassociatedwiththediffusionsimulationmodel).•Migrationofradionuclidesfromseawatertobeachsediments.(Themigrationfactorfromwatertobeachsedimentsforthecalculationofexternaldoseisnotelementdependent,sothereisuncertaintyassociatedwiththedoseconversionfactor).•Transferofradionuclidesfromseawatertoaquaticfoods.(Theconcentrationfactorforfishisuncertain,particularlyforsomeelements,duetoinsufficientdata).•Selectionofexposurepathways.(Thereareuncertaintiesassociatedwithnotnecessarilyhavingcoveredallpossibleexposurepathways).•Selectionoftherepresentativeperson.(TheareaaroundtheFDNPSisundergoingreconstruction,sohabitdatafrombeforetheaccidenthavebeenused.Asaresult,thereareuncertaintiesduetotheactualhabitsatthecurrenttimenotbeingknownindetail.Thereisuncertaintyassociatedwiththeseaareachosenasbeingrepresentativeofwhereseafoodconsumedbytherepresentativepersoniscaught).Ineachcase,detailsoftheassessmentandthecalculationscarriedouttoshowthesensitivityoftheresultsoftheREIAaregiven.Takingaccountofuncertainties,theestimateddosestotherepresentativepersonduetothedischargesofALPS-treatedwaterwillbefarbelowthedoseconstraint.RegulatoryReviewoftheREIAAsdescribedinSection3.1,priortoapprovaloftheImplementationPlanandtheauthorizationofdischarges,NRAreviewstheImplementationPlan,includingtheREIAanddocumentsitsfindingsinthe‘ReviewResultsDocument’.ThedraftresultsofitsreviewoftheREIAarediscussedwithTEPCOinpublicmeetings.TheTaskForcewasinformedatbothNRAmissionsthatduringthereviewmeetingswithTEPCO,anumberoftopicshadbeendiscussedwithTEPCOthatrequiredchangesandupdatestobemadetotheREIAandthatithadbeenaniterativeprocess.NRAalsopublishesitsdraftReviewResultsDocumentfor30daysofpublicreviewandcommentaspartoftheprocess.AnoverviewofthemajormilestonesinthisprocessisincludedinAnnex3.TheNRApresentedtotheTaskForcethemainpointsraisedinthediscussionswithTEPCOandtheirrequestsforclarificationsandfurtherworkontheREIA.TheTaskForcenotedthattheinternationalsafetystandardsstatethattheregulatorybody‘shouldagreethatthemethodologyadoptedisadequateforitsproposedpurpose’indiscussionwiththeapplicant(GSG-9),whichNRAhasdone.NRAexplainedthatithadundertakenanindependentverificationofTEPCO’smarinedispersionmodelandtheypresentedtheresultstotheTaskForce.NRAalsopresenteddetailsandupdatesregardingitsongoing(atthetimeofthemissionheldinJanuary2023)reviewoftheNovember2022versionoftheImplementationPlanandREIA.TheTaskForcespecificallynotedthatNRAhasreviewedTEPCO’sapproachforcalculatingactivityconcentrationsintheaquaticenvironmentwhichisanimportanttopicraisedbytheTaskForceandotherinterestedparties.3.4.3ConclusionsTheIAEAhasconcludedthattheapproachtakenbyTEPCOandtheNRAisconsistentwiththerelevantinternationalsafetystandardsincludedunderthissectionofthereport.Furtherdetailedfindingsareincludedbelow:•AREIAhasbeenproducedandiscompliantwiththeinternationalsafetystandards.TheREIAfollowstheassessmentapproachgiveninIAEAGSG-10[11]forprotectionofthepublicin84normaloperations.Theresultingdosesareatleastafactorof1000lowerthanthedoseconstraintof0.05mSvperyear.•Fortheassessmentoftheradiologicalimpactofaccumulationofradionuclidesinseabedsediments,relativelysimplemodelsareappliedintheREIA.However,theapproachtakenensuresthattheresultingannualdosesovertheperiodoftheplanneddischargearenotunderestimated.•TheREIAcontainsanassessmentofdosestofloraandfaunausingtheapproachgiveninGSG-10,whichisin-linewiththeICRPapproach[12;13].Theestimateddoseratestothethreemarinerepresentativeanimalsandplantsconsidered(flatfish,crabandseaweed)aremorethan1milliontimeslowerthanthederivedconsiderationreferencelevelssetbyICRP.•IntheREIA,TEPCOhasincludedanassessmentofthepotentialdosestoarepresentativepersonfromtwoidentifiedscenariosresultingintheunintendeddischargeofALPStreatedwater.Consideringallagesandtankgroupstheresultingpotentialdosesaremorethanafactorof100lowerthantherecommendedcriterionsetbyNRAof5mSv.•TheREIAincludesthesensitivityofthedosesestimatedtotherepresentativepersonandtoreferenceanimalsandplantsforrelevantassumptionsmadebyTEPCO.Takingaccountofuncertainties,theannualdosestotherepresentativeperson(adult,childrenandinfants)willbefarbelowthedoseconstraintof0.05µmSvperyear.•NRAhasaniterativeprocessforreviewingtheREIAwithTEPCO.Thereviewprocessincludesopportunityforthepublictocomment.3.5.SourceandEnvironmentalMonitoring3.5.1BackgroundTherearetwogeneraltypesofmonitoringthatareappropriateinthecontextofcontrollingdischargesandtherelatedpublicexposure.AsnotedinGSG-9[9],paragraph5.75,theseare:a)Monitoringofthesource,whichinvolvesmeasuringactivityconcentrationsordoseratesatthedischargepoint.b)Monitoringoftheenvironment,whichinvolvesthemeasurementofradionuclideconcentrationsinenvironmentalmedia(includingfoodstuffanddrinkingwater)andofdosesordoseratesduetosourcesintheenvironment.”Requirement14ofGSRPart3[8]onmonitoringforverificationofcompliancestatesthat“Registrantsandlicenseesandemployersshallconductmonitoringtoverifycompliancewiththerequirementsforprotectionandsafety.”Inaddition,Paragraph3.54ofGSG-8[10]statesthat“Suchmonitoringshouldprovidesufficientinformationtodeterminewhetherthelevelsofpublicexposurescomplywiththedoselimitsandtodemonstratethatprotectionandsafetyisoptimized.”Paragraph3.37ofGSRPart3[8]states:“Theregulatorybodyshallestablishrequirementsthatmonitoringandmeasurementsbeperformedtoverifycompliancewiththerequirementsforprotectionandsafety.Theregulatorybodyshallberesponsibleforreviewandapprovalofthemonitoringandmeasurementprogrammesofregistrantsandlicensees.”85Inaccordancewithparagraph3.38ofGSRPart3[8],allmonitoringactivitiesarerequiredtoadheretoestablishedcriteriaforqualityassurancecovering,interalia,thedesignandimplementationofthemonitoringprogrammes,includingproperlymaintainedandcalibratedequipment,samplinglocations,suitablyqualifiedandtrainedpersonnelanddocumentedprocedures.Inaccordancewithparagraph3.137ofGSRPart3[8],thelicenseeisrequiredtodothefollowing:•Establishandimplementmonitoringprogrammestoensurethatpublicexposureduetothedischargesisadequatelyassessedandthattheassessmentissufficienttoverifyanddemonstratecompliancewiththeauthorization;•Maintainappropriaterecordsoftheresultsofthemonitoringprogrammes;•Reportormakeavailabletotheregulatorybodytheresultsofthemonitoringprogrammeatapprovedintervals;•Reportpromptlytotheregulatorybodyanylevelsexceedingtheoperationallimitsandconditionsrelatingtopublicexposure,includingauthorizedlimitsondischarges,inaccordancewithreportingcriteriaestablishedbytheregulatorybody;•Reportpromptlytotheregulatorybodyanysignificantincreaseindoserateorconcentrationsofradionuclidesintheenvironmentthatcouldbeattributedtothedischarges,inaccordancewithreportingcriteriaestablishedbytheregulatorybody;•Establishandmaintainacapabilitytoconductmonitoringinanemergencyintheeventofunexpectedincreasesinradiationlevelsorinconcentrationsofradionuclidesintheenvironmentduetoanaccidentorotherunusualeventattributedtothedischarges;•Verifytheadequacyoftheassumptionsmadefortheassessmentofpublicexposureandtheassessmentforradiologicalenvironmentalimpacts.InaccordancewithGSG-9[9],itisrecommendedtodeterminetherequirementsformonitoring,includingfrequency,bytheassessedlevelofriskofradiologicalimpact.Withregardtoenvironmentalmonitoring,GSG-9[9]providesrecommendationsonconductingapreoperationalanalysis(beforethedischargesstart)todeterminetheexistinglevelsofbackgroundradiationintheenvironmentsurroundingthefacilitypriortothefirstdischargeandtoestablishabaseline.InaccordancewithRS-G-1.8[16],morefrequentanddetailedenvironmentalmeasurementsmaybeneededintheearlystagesofoperationandallmonitoringprogrammesarerecommendedtobesubjecttoperiodicreviewtoensurethatmeasurementscontinuetoberelevantfortheirpurposes.Theregulatorybodyplacesrequirementsontheoperatorforthefrequencyforreportingofresultsandtheformandrequiredcontentofthereports.Paragraph5.76ofGSG-9[9]statesthat“Therequirementsforsourcemonitoringandenvironmentalmonitoringshouldbespecifiedintheauthorizationfordischargesbytheregulatorybody.Thenecessityforandfrequencyofmonitoringshouldbedeterminedbytheassessedlevelofriskofradiologicalimpact.”Theregulatorybodyisalsoresponsibleforreviewandapprovalofmonitoringprogrammes,forensuringtheirproperimplementationandforrecordingandmakingavailabletheresults.Theregulatorybodyalsoneedstoperiodicallyperformanindependentreviewofthelicensees’orregistrants’source(andenvironmental)monitoringprogrammesandmakeprovisionforindependentmonitoring.Paragraph5.74ofGSG-9[9]statesthat“Theoperatingorganizationshouldmakeavailable,onrequest,resultsfromsourcemonitoring.Thisrequestmaybeincorporatedwithintheoperationallimitsandconditionsoftheauthorizationorspecifiedinotherregulatorydocuments.”Paragraphs5.84–5.85ofGSG-9[9]providerecommendationsforindependentmonitoringtotheregulatorybody.Paragraph5.85statesthat;“Thepurposeofsuchindependentmonitoringmaybeoneormoreofthefollowing:86a)Toverifythequalityoftheresultsprovidedbytheoperatingorganization;b)Toverifytheassessmentofdosestotherepresentativeperson”Paragraph5.6ofRS-G-1.8[16]statesthat‘Oneofthemaingoalsofthemonitoringprogrammeistochecktheassumptionsandvalidatetheresultsofthesafetyassessment.Thus,themonitoringprogrammeshouldpayparticularattentiontothecritical[exposure]pathwaysandcriticalradionuclides.”3.5.2ReviewandAssessmentSourcemonitoringTEPCO’sapproachforsourcemonitoringisbasedonsamplingandlaboratorymeasurementsofactivityconcentrationsinthesample(‘batchdischarges’)andsubsequentconfirmationthattheresultsdemonstratecompliancewiththeauthorizeddischargelimits.ThisisinlinewithSafetyGuideRS-G-1.8para5.18[16]whichstates:“Inthecaseofbatchdischarges,thematerialfordischargeisadequatelycharacterizedbythevolumeofthebatchandtheradionuclidecompositionofasampletakenatthereservoirfromthehomogenizedbatchpriortodischarge”.DischargemethodologyTEPCOhasprovideddetailsofitsdischargemethodology,thedischargefacilitythatithasconstructedatFDNPSanditssourcemonitoringplaninitsImplementationPlanandtheREIAcontainedtherein.Priortoagivendischargeoccurring,ALPStreatedwaterwillbetransferredfromindividualtanksattheFDNPSsiteintothemeasurementandconfirmationfacilities.ThemeasurementandconfirmationfacilityisshownwithinthecontextofthebroaderALPSprocessing,storageanddischargefacilitatesinFigure3.20.Themeasurementandconfirmationfacilitiesarecomprisedofthreegroupsoftanks,witheachtankgroupcontaining10interconnectedtanks.IfneededthewaterwillbefirsttreatedagainusingasecondaryALPStreatment,beforebeingtransferredtothemeasurementandconfirmationfacilities.CirculationandagitationwillbeappliedineachtankgrouptoensurehomogeneityoftheALPStreatedwaterpriortocollectingrepresentativesamplesandperformingconfirmatorymeasurementstoensurethatthesumofratiosofthelegallyrequiredactivityconcentrationsofradionuclidesotherthantritiumislessthanone(seeSection3.3).ThetotalvolumeofALPStreatedwatercontainedinasingletankgroupcanberegardedasa‘batch’(accordingtoRS-G-1.8para5.18).Thetotalradionuclidecontentofallbatchesdischargedperannumdefinesthesourcewhichiscomparedtoauthorizedlimitsondischarges(inBqperyear).TheproposedmethodologyformeasurementandconfirmationthateachbatchofALPStreatedwatercomplieswiththeregulatoryconcentrationlimitspriortodischargecanbesummarized(foreachgroupof10tanksinthemeasurementandconfirmationfacility)asfollows:1.Anemptytankgroupinthemeasurementandconfirmationfacilityisfilled.2.Homogeneityisachievedthroughagitation(intra-tank)andcirculation(inter-tank)[20].3.Asinglesampleistakenforconfirmatoryanalysesforall30radionuclidesintheALPSsourceterm.4.Ifthedataindicatescompliancewiththedischargeauthorization,valvesareopenedtoallowtheALPStreatedwatertobetransferredfordilutionanddischarge.SamplescollectedfromthemeasurementandconfirmationfacilityarethefocusoftheIAEA’scorroborationofsourcemonitoring.87Dischargeverticalshaft(upper-streamstorage)DischargetunnelsUnit5intakechannelWasteSrremovedWater,etc.ALPSALPStreatedWater,etc.ALPStreatedWaterSampletankofALPSorALPStreatedwaterstoragetankStoragewatertransferpumpSecondarytreatmentfacilitySumofratiosoftheconcentrationofeachradionuclideothertantritiumtotheregulatorystandardofeachislessthanoneALPStreatedwaterdilution/dischargefacilityMeasurement/confirmationfacilityMeasurement/confirmationtanksSamplingandanalysisTransferpumpforALPStreatedwaterTransferpump150m3/dayormoreTransferFacilityEmergencyisolationvalveTritiumconcentrationafterdilutionlessthan1,500Bq/LDilutionFacilityDischargefacilityOutletThewaterismixedanddilutedwithseawatertakenfromtheseaandtransformedtothedischargeverticalshaftDischargeverticalsaft(down-streamstorage)SumofratiosoftheconcentrationofeachradionuclideotherthanktritiumtotheregulatorystandardofeachismorethanoneSeawatertransferpumpSeawaterpipheaderFigure3.20.ALPSprocessing,storageanddischargefacilitiesGroupA(10TANKS)GroupB(10tanks)GroupC(10tanks)(5tanks)K4-A1K4-A2K4-A3K4-A4K4-A5K4-A10K4-A9K4-A8K4-A7K4-A6K4-B1K4-B2K4-B3K4-B4K4-B5K4-B10K4-B9K4-B8K4-B7K4-B6K4-C1K4-C2K4-C3K4-C4K4-C5K4-D10K4-D9K4-D8K4-D7K4-D6K4-E1K4-E2K4-E3K4-E4K4-E5K4areatankgroup:35tanksAgitationdemonstrationtest:PerformedinNovember2021Circulationandagitationdemonstrationtest:PerformedinFebruary2022Temporarycirculationpump(B)Temporarycirculationpump(B)Circulationlinesamplingpoint(B)Circulationlinesamplingpoint(B)ChargetribasicsodiumphosphateK4-B2K4-B2K4-B3K4-B4K4-B5K4-B6K4-B8K4-B9K4-B10AgitatorK4-B7Figure3.21.InfrastructureusedbyTEPCOtoensurehomogeneityofALPStreatedwaterinthemeasurementandconfirmationfacility88HomogeneityandrepresentativesamplingToensurethatsamplestakenfromeachbatcharerepresentative,achievinghomogeneityinthemeasurementandconfirmationtanksisfundamental.TEPCOhascarriedoutanexperimenttodemonstratehowitintendstoachievehomogeneitythroughagitation(intra-tank)andcirculation(inter-tank).Theexperimentwasbasedontheadditionofaknownconcentrationofastable,easytomeasuretracer–tribasicsodiumphosphate–intothetankgroupcontents(seeFigure3.21).Circulationandagitationwasthenperformed.Samplesofthephosphatetracerweretakenbeforehand,whilecirculationandagitationwasinprogressandafter144hours(6days)hadpassedwhentherewasindicationthatsufficienthomogeneitywithinthetankgroupcontentshadbeenachieved.Analysisofthelattersamples,30intotaltakenatthreelocations–upper(10m),middle(5m)andlower(1m)–fromeachofthe10individualtanksdemonstratedarelativestandarddeviationinphosphateconcentrationsof10.5%.Therewasalsoconsistency,withinmeasurementuncertainty,betweentheknownvolumeofphosphateaddedandthatdeterminedfollowingdilutioninthetankgroupcontentsfromthesemeasurements.TEPCOalsoanalysedthe30samplesforactivityconcentrationsoftritiumandotherradionuclidesthatcouldbedetected(60Co,90Sr,129I,137Cs)andcomparedthemtoresultsfrombeforethehomogeneitytest[19].Therelativestandarddeviationfortritiumwas1.9%,reducedfrom8.1%.Thedegreeofheterogeneityinactivityconcentrationsmeasuredateachpointineachindividualtankwasalsodemonstratedtobelowerfortheotherradionuclides,withtheexceptionof60Cowhicheffectivelyremainedthesame.Therelativestandarddeviationsfortheseradionuclidesfollowingcirculationandagitationrangedfrom4.5%to14.9%.Onthebasisofthisexperiment,TEPCOconcludedthatanadequatedegreeofhomogeneitythatwouldallowforrepresentativesamplestobetakenhadbeenachieved.Equivalentequipmentforcirculationandagitationhasbeenincorporatedintoitsoperationalplanformanagingthedischarges.Toensuretheongoingeffectivenessofthisprocess,themaintenanceofthisequipmentisincludedinthegeneralmaintenanceplanforthemeasurementandconfirmationfacilitiesthatTEPCOhasdeveloped.TEPCOsharedthismaintenanceplanwiththeIAEAandhassubmittedittotheNRAforapprovalaspartoftheNRA’sinspectionprogramme.MeasurementandconfirmationTheradionuclidestobemeasuredandconfirmedasbeingbelowregulatorylimitspriortodischargeofeachbatchofALPStreatedwaterarethoseidentifiedinthesourceterm(seeSection3.3).Thedetectionlimitofeachmethodisinformedbytheregulatorylimitfordischargeofeachrespectiveradionuclide–TEPCO’stargetfordetectionlimitsis<1%oftherespectiveregulatorylimit.TheresultsofthefirstILCforcorroborationofsourcemonitoring[1]showedthattheyhaveachievedthisdetectionlimitforall30radionuclidesintheALPStreatedwatersourceterm(seeTable3.10).Alotofradionuclide-specificmeasurementdataexist–overmanyyearssince2011,fromdifferentpointsintheprocessingstream,coveringabroadrangeofradionuclides.Theseincludelong-lived,high-yieldfissionandneutronactivationproducts,andisotopesofuraniumandtransuranics,includingisotopesofNp,Pu,Am,andCm.89TABLE3.10.COMPARISONOFTEPCO’SDETECTIONLIMITSWITHRESPECTIVEJAPANESEREGULATORYLIMITSFORDISCHARGE(Table9[1])Regulatorylimit(RL)(Bq/L)Detectionlimit(DL)(Bq/L)DLrelativetoRL(%)3H600002100.3514C20001.60.08054Mn10000.0470.004755Fe2000190.9460Co2000.0280.01463Ni60008.10.1379Se2000.850.4390Sr300.0690.2399Tc10000.430.043106Ru1000.420.41125Sb8000.100.013129I90.0260.29134Cs600.0570.10137Cs900.0360.040144Ce2000.590.30147Pm30000.320.011151Sm80000.0120.00015154Eu4000.0720.018155Eu30000.190.0063234U200.0310.15238U200.0310.15237Np90.0310.34238Pu40.0310.76239Pu40.0310.76240Pu40.0310.76241Pu2000.840.42241Am50.0310.61244Cm70.0310.44TEPCOhasputsignificanteffortintocharacterizingthesourcetermand,becausethisisalreadymorethansufficientlyconservative,theIAEAsupportsusingthelistofradionuclidesidentifiedasabasisforsourcemonitoring.IAEAdoesnotrecommendmonitoringforadditionalradionuclides,especiallythoseidentifiedinearlyiterationsofthemethodology.Theseincludeshort-livedradionuclides.Monitoringfortheseradionuclidesthatcouldnotpossiblybepresentinthewatermorethan12yearsaftercoldshutdowncouldresultinconfusion.TEPCOhasestablishedaqualitymanagementsystem(QMS)fortheanalysisofradionuclides(forbothsourceandenvironmentalmonitoring).TheNRAinspectsthisandotherlaboratoryandqualitymanualsbeforethestartofoperation,andasnecessaryoncethedischargesareinoption.TheaspectsofTEPCO’sQMSsubjecttoinspectionincludeprocurement,analyticalmethoddevelopment,humanresourcesandtraining,maintenanceandcalibrationofinstruments,anddocumentmanagementandrecordkeeping.EachofthesehasbeenlinkedtorelevantclausesofISO9001[20]andISO/IEC17025[21]asevaluationcriteriathatareutilisedduringNRA’sinspections.90TEPCO’ssamplingandanalyticalmethodsforbothsourceandenvironmentalmonitoringrelatedtoALPStreatedwaterhavealsobeenreviewedbytheIAEA.Thisinvolvedbothdesktopandonsitecomponents(atechnicalreviewofTEPCO’slaboratoriesatFDNPSwasconductedMarch2023),inwhicharepresentativeexampleofrelevanttechnicalrecordsatTEPCO’sFDNPSlaboratorieswereassessed.ALPStreatedwaterhasbeencharacterizedforalphaemittersasperthesourceterm.Reportedactivityconcentrationsareoften<1/100thoftheregulatorylimit.Toensureeffectiveuseofresourcesandoptimizationofanalysistimewhilstremainingfitforpurpose,theutilizationofagrossalphascreeningmethodisjustified.Apre-definedactionlimitisset,andifitisexceeded,astructuredresponseplanisinplace.Whendischargesareoperational,dailymonitoringoftritiuminsamplesofdilutedALPStreatedwatercollectedfromthedischargepipingafterdilutionwillalsobeundertakenbyTEPCOtoensurethatthereiscompliancewiththedischargelimitof1,500Bq/Lfortritium.Thissamplingpointwillbeclosesttothedischargepointand,beingdiluted,thesampleswillbeidenticaltotheALPStreatedwateractuallyreleasedintotheenvironment.IndependentmonitoringbyNRAGSG-9requiresthatindependentmonitoringshouldbeundertakenbytheregulatorybodyoronbehalfoftheregulatorybodybyanotherorganizationthatisindependentoftheoperatingorganization.TheNRAhasundertakenaverificationofTEPCO’ssourcemonitoring.ItcontractedaTechnicalSupportOrganization(TSO)laboratory(JAEA,NuclearSafetyResearchCentre)toanalyseasampleofALPStreatedwatertakenpriortothestartofdischargesforasubsetofradionuclides:tritium,14C,36Cl,55Fe,60Co,79Se,90Sr,99Tc,106Ru,125Sb,129I,134Cs,137Cs.ThesamplewastakenatthesametimeasthoseusedfortheIAEA’s1stILCforcorroborationofsourcemonitoring[1];TEPCOreportedidenticalresultsforbothexercises.ForradionuclidesforwhichactivityconcentrationsabovedetectionlimitswerereportedbybothTEPCOandJAEA,theresultswerecomparedagainstTEPCO’sresultsusingscores[22].Allsuchresults(tritium,14C,60Co,90Sr,99Tc,129I,137Cs)werefoundtobeinagreement,althoughJAEAwererequiredtore-analysethesamplefor14C.Additionally,NRArequiresthatcertainradionuclidesareanalysedfortheirpresenceinALPStreatedwater(separatefromtheanalyticalcomparisonwithTEPCOresults)asanadditionallevelofindependentassessment.TheanalyticalresultspreparedforNRAincludetheidentificationofanydiscrepanciesandtheirpotentialcause.NRAexplainedtheprocessforrespondingtodiscrepanciesbetweentheindependentmonitoringandTEPCOmeasurementsandthattheinformationrequiredforarootcauseanalysis(e.g.,qualityassuranceandcontrolprocesses,analyticalmethod/instrumentationused)shouldbedefinedinadvance.SamplescollectedfromtheK4-BtankgroupwerethefocusoftheIAEA’sfirstInterlaboratoryComparison(ILC)forcorroborationofsourcemonitoring[1]andSection4.TheresultsofthisILCconfirmedtheappropriatenessofTEPCO’sanalyticalmethodsandsamplecollectionprocedures,includingthetechniquesusedtoensurehomogeneityandthustoobtainrepresentativesamples.EnvironmentalmonitoringMonitoringofthemarineenvironmentinvolvesthemeasurementofradionuclideconcentrationsinenvironmentalmedia(includingseawater,sediments,seafoodandfloraandfauna).Theobjectives91ofenvironmentalmonitoringaretoverifytheresultsofsourcemonitoringandtheadequacyoftheassumptionsmadefortheassessmentofpublicexposureandtheassessmentofradiologicalenvironmentalimpacts.Additionalreasonsforenvironmentalmonitoringaretodetectanyunpredictedchangesinactivityconcentrationsandtoevaluatelongtermtrends;toprovidedatatoenabletheassessmentofactualorprospectivedosestothereferenceperson;andtoprovideinformationtothepublic.Environmentalmonitoringisconductedoff-site.Theactivityconcentrationsdetectedinenvironmentalmonitoringarenormallylowerthanthoseestimatedbyconservativemodels,and,consequently,retrospectivedosecalculationsareoftenbasedonsourcemonitoringdataandappropriatemodelling.TheGovernmentofJapan’sComprehensiveRadiationMonitoringPlan(CRMP)[7]isacoordinatedinitiativeundertakenbygovernmentagenciesaimedatmonitoringandmanagingradiationlevelsthroughoutthecountry.ItiscoordinatedjointlybytheMinistryofEnvironmentandNRA.ItwasdevelopedinApril2011inresponsetotheaccidentatFDNPSandhasbeenreviewedandrevisedasnecessaryeachyearsince[7].TheobjectivesoftheCRMPinclude:MonitorRadiationLevels:TheCRMPhasestablishedacomprehensivemonitoringsystemtocontinuouslymeasureradiationlevelsinenvironmentalmedia,includingair,soil,water,andfood.AssessHealthRisksandPlanandEvaluateInterventions:Thecollecteddataareanalyzedtoassessthepotentialhealthrisksassociatedwithradiationexposure.Thisincludesevaluatingtheimpactonindividuals,communities,andtheenvironment,andidentifyinganyareasorpopulationsthatmayrequirespecificattentionorinterventionsuchasdecontaminationorre-evaluationofevacuationzones.EnsureTransparencyandCommunication:TheCRMPemphasizeseffectivecommunicationoferesultsofmonitoringtothepublic.Byprovidingaccurateandaccessibleinformation,theplanaimstoenhancepublicawareness,understanding,andconfidenceinradiationmonitoringefforts.EnvironmentalProtection:TheCRMPfocusesonsafeguardingtheenvironment,includingmarineecosystems,fromthepotentialimpactsofradiation.Itincludesmonitoringandassessingthetransferofradioactivitybetweendifferentenvironmentalcompartments,forexampleseawater,marinesedimentsandbiotasuchasfish,shellfishandseaweed.ThemarinemonitoringcomponentoftheCRMPdefinessamplinglocations,frequencyofsampling,detectionlimitsandresponsibilitiesoftheorganizationsinvolved.Monitoringcomprisessamplingandanalysisofseawatertodifferentdepths,sedimentandmarinebiota(fish,shellfishandseaweed)andisseparatedintozonesatvaryingdistancesfromtheFDNPSsitewhichare:theseaareaclosetoFDNPS;thecoastalarea;theoff-shorearea;andtheouterseaarea.Theaimofthisplanincludesensuringacomprehensiveoverviewoftheradiologicalsituationinthemarineenvironmentandprovidinganadequatebasisforassessmentsofradiationexposuresfrommarinepathways.WithaviewtoassistingtheGovernmentofJapaninitsobjectiveofmakingthemarinemonitoringcomponentoftheCRMPcomprehensive,credibleandtransparent,theIAEA,throughitsMarineEnvironmentLaboratories,ishelpingtoensurethehighqualityofdataandtoprovethecomparabilityoftheresults.Aproject‘MarineMonitoring:ConfidenceBuildingandDataQualityAssurance’wasinitiatedin2014asafollow-upactivitytorecommendationsmadeonmarineradioactivitymonitoringinareportissuedbytheIAEAin2013whichreviewedJapan’seffortstoplanandimplementthedecommissioningoftheFDNPS.Theprojecthasbeenextendedseveraltimessince.Sofar,10samplingmissionsandinterlaboratorycomparisons(ILCs)and7proficiencytests(PTs)havebeencompletedandtheprojectisongoing.92TodatetheresultsoftheILCs,publishedasIAEAreports,forexample[26;27],haveconcludedthatJapan’ssamplecollectionproceduresfollowtheappropriatemethodologicalstandardsrequiredtoobtainrepresentativesamplesandthatJapaneselaboratoriesinvolvedintheanalysesofradionuclidesinmarinesamplesfortheCRMPdemonstrateahighlevelofaccuracyandcompetence.TheseresultsarebackedupupbytheconclusionsofthePTs.Moreinformationonthisworkisavailablethroughadedicatedwebsite6.TheIAEAisalsocorroboratingtheresultsofenvironmentalmonitoringundertakenspecificallytoaddressthedischargesofALPStreatedwater(seePart4.2andthisSection).Thelocationsatwhichsamplesarecollectedforanalysisininterlaboratorycomparisonsforthenearshoreseaarea,coastalseaareaandoffshoreseaarea[28].RevisionofJapan’sComprehensiveRadiationMonitoringPlanJapan’sComprehensiveRadiationMonitoringPlan(CRMP)has,sinceMarch2022,beenrevisedtoaddressALPStreatedwaterdischarges.Anexpertgroup(nominatedbytheGovernmentofJapan)providedguidanceontheenhancementoftheCRMPtoaddresstheALPStreatedwaterdischargesandwillcontinuetobeutilizedtoprovideadviceondetailsoftheenvironmentalmonitoringtakingplacearoundFDNPS.AnoverviewoftheinteractionoftheexpertgroupwiththeMOE(coordinatorofmarinemonitoringwithintheCRMP),theNRAandTEPCOasadataproviderisschematizedinFigure3.22.Theexpertgrouphasconsideredtheparameterssetregardinglocationandfrequencyofenvironmentalsamplingandwillalsobeinvolvedinreviewingthemonitoringdata.ThecoordinationoftheorganisationscontributingtotheCRMPandtheexpertgroupispresentedinFigure3.22.TEPCORegulationDataAdviceandconfirmationExpertmeetingNRAMOEFUKUSHIMAPref.FAJFigure3.22:TheinteractionoftheexpertgroupwiththeMOE(coordinatorofmarinemonitoringwithintheCRMP),theNRAandTEPCOTherevisedplanincludesmonitoringoftritiuminseawateratanincreasedfrequencyplustheidentified“sevenmajorradionuclides”inseawaterquarterly.Monitoringoforganicallyboundtritium(OBT),free-watertritium(FWT)and14Cinfishand129Iinseaweedhasalsobeenundertaken.AsalreadystatedinSection3.4,theradionuclidescontributingmosttoingestiondoses-over90%ofthetotal–are129I,14C,55Feand79Se.TheseradionuclidesareincludedintheCRMP:125Iismeasuredinseaweed(asabioindicator);14C(infish);and55Feand79Seinseawateronceayear.6https://www.iaea.org/about/organizational-structure/department-of-nuclear-sciences-and-applications/division-of-iaea-marine-environment-laboratories/marine-monitoring-confidence-building-and-data-quality-assurance)93BaselinemonitoringBaselinemonitoringhasstartedandisinlinewithGSG-9recommendationsonconductingapreoperationalanalysis(beforethedischargesstart)todeterminetheexistinglevelsofbackgroundradiationintheenvironmentsurroundingthefacilitypriortothefirstdischargeandtoestablishabaseline.ItisalsoinaccordancewiththepossibleneedformorefrequentanddetailedenvironmentalmeasurementssuggestedbyRS-G-1.8[16],whichmaybeneededintheearlystagesofoperation.Themonitoringprogrammesshouldbereviewedperiodicallytoensurethatitcontinuestoberelevantforitspurposes.Thebaselinemonitoring,alongwithmeasurementsmadeinthevicinityofJapanandthewiderAsiaPacificregionisimportanttoestablish‘background’levelsofradionuclidesintheoceansandmarinebiotaandseafood.TheactivityconcentrationsinthemarineenvironmentestimatedintheREIAareverylowcomparedtotheavailablemeasuredvaluesintheregion[24].ItisexpectedthattheresultsfromthemonitoringundertakenbyTEPCOandwithintheCRMPwillnotbestatisticallydistinguishablefromthe‘background’values,atdistancesofafewkmfromtheFDNPS.Therefore,anymeasurableconcentrationsoftritium,orotherradionuclidesintheAsiaPacificregion(orbeyond)shouldnotautomaticallybeattributedtothedischargedwaterfromtheFDNPS.IndependentmonitoringbyNRAGSG-9alsorequiresthatindependentmonitoringshouldbeundertakenbytheregulatorybodyoronbehalfoftheregulatorybodybyanotherorganizationthatisindependentoftheoperatingorganization.TheNRAhasprovideddetailsonhowtheresultsofTEPCO’smonitoringwillbeassessedandcomparedagainstthosefromtheorganizationsindependentofTEPCOundertheCRMP[7].NRA’srequirementsonTEPCOforidentifyingandresolvingdiscrepanciesbetweenTEPCO’smonitoringresultsandthosefromindependentmonitoring(CRMP)havealsobeendescribed.Thisinvolvesstatisticalanalysisofthetime-seriesofmeasurementresultsforeachradionuclidefromeachsamplinglocationbyNRA.Anydiscrepancieswillbeevaluatedagainsttheresultsfromneighbouringsamplinglocations.FurtherinformationontheIAEA’sindependentcorroborationofenvironmentalmonitoringcanbefoundinPartIVofthisreport.LinkofmonitoringprogrammetoREIATheTaskForcediscussedwithTEPCOandNRAtheimportanceofusingtheenvironmentalmonitoringprogrammetohelpverifytheimpactofdischargesonenvironmentalconcentrationsanddosesthathavebeencalculatedintheREIA;thisisoneoftherolesofenvironmentalmonitoringdescribedintheinternationalSafetyStandards.TheimportanceoflinkingreviewsoftheenvironmentalmonitoringprogrammetotheresultsoftheREIAisvitallyimportantandwasalsodiscussed.Thiswillensurethatenvironmentalmonitoringisfocussedonthemostimportantradionuclidesandexposurepathwayscontributingtothedosestothepublic.943.5.3ConclusionsTheIAEAhasconcludedthattheactivitiesandapproachtakenbyTEPCOandNRAareconsistentwiththerelevantinternationalsafetystandardsincludedunderthissectionofthereport.Furtherdetailedfindingsareincludedbelow:•TheIAEAacknowledgesthatclearlydefinedplansforsourcemonitoringcoveringsamplingandanalysisatthemeasurementandconfirmationfacilityisinplace.Additionallyplansforsamplingofwaterafterdilutionarealsonoted.•TEPCOhasputsignificanteffortintocharacterizingthesourcetermand,becausethisisalreadysufficientlyconservative,theIAEAsupportsusingthelistofradionuclidesidentifiedasabasisforsourcemonitoring.•IAEAhasfoundTEPCO’smethodologytoachievehomogeneityandthusrepresentativesamplestobeappropriate.•QualitycriteriaforbothsourceandenvironmentalmonitoringhavebeenclearlydefinedbytheNRAandobservedtohavebeenmetbyTEPCO.•ArrangementsforindependentmonitoringbytheNRA,forsourcemonitoring,werefoundtoadheretotherequirementsoftheinternationalsafetystandards.•AclearlydefinedplanforenhancedenvironmentalmonitoringbyTEPCOandtheGovernmentofJapantoaddressthedischargesofALPStreatedwaterisinplace.•TheactivityconcentrationsinthemarineenvironmentestimatedintheREIAareverylowcomparedtotheavailablemeasuredvaluesintheregionandthesewillnotbedistinguishablefromthe‘background’values,atdistancesofafewkilometresfromtheFDNPS.•DuetotheuniquenatureofJapan’sCRMP,governmentagencies(suchasNRA)andTEPCOconductmonitoringindependentlybutaccordingtoacommonplan.Arrangementsforcheckingdataforconsistencyandtheidentificationandinvestigationofdiscrepanciesareinplace.3.6.InvolvementofInterestedParties3.6.1BackgroundInaccordancewithGSRPart3[8],thegovernmentortheregulatorybodyarerequiredtoprovideinformationto,andengageinconsultationwith,partiesaffectedbyitsdecisionsand,asappropriate,thepublicandotherinterestedparties.IntheIAEAinternationalsafetystandards,theterminterestedpartiesisusedinabroadsensetomeanapersonorgrouphavinganinterestintheactivitiesandperformanceofanorganization.Inthecontextofradioactivedischargestotheenvironment,‘interestedparties’typicallyincludeindividualsororganizationsrepresentingmembersofthepublic;industry;governmentagenciesordepartmentswhoseresponsibilitiescoverpublichealth,nuclearenergyandtheenvironment;scientificbodies;thenewsmedia;environmentalgroups;andgroupsinthepopulationwithparticularhabitsthatmightbeaffectedsignificantlybythedischarges,suchaslocalproducersandindigenouspeopleslivinginthevicinityofthefacilityoractivityunderconsideration.GSRPart3[8]states:95“3.124.WhenasourcewithinapracticecouldcausepublicexposureoutsidetheterritoryorotherareaunderthejurisdictionorcontroloftheStateinwhichthesourceislocated,thegovernmentortheregulatorybody:…(c)ShallarrangewiththeaffectedStatethemeansfortheexchangeofinformationandconsultations,asappropriate.”Paragraph5.99ofGSG-9[9]states:“Becausetheregulatorycontrolofradioactivedischargestakesintoaccountbothoperationalandsocietalaspects,suchasradioactivewastemanagementinthefacilityandtheoptimizationofthelevelofprotectionofthepublic,thereareanumberofdifferentinterestedpartieswhoseviewsshouldbeconsidered,asappropriate.Aprocessresultinginthegrantingofanauthorizationfordischargesislikelytonecessitateanexchangeofinformationbetweentheregulatorybody,theapplicant,andotherinterestedparties.SomeinterestedpartiesmaybelocatedinotherStates,especiallyinneighbouringStates.”Paragraph5.101ofGSG-9[9]furthernotesthat:“Insomecases,theremaybespecificrequirementsfortheexchangeofinformationwithinterestedpartiesbeforetheauthorizationfordischargeshasbeenfinalized.Onemeansofdoingthisisthroughtheestablishmentofagroupreflectinglocalpublicconcernsforliaisonwithboththeoperatingorganizationandtheregulatorybody.Amongotherthings,theresultsoftheprospectiveradiologicalenvironmentalimpactassessmentshouldbeafocalpointofthediscussions.”Anyexchangeofinformationrelatingtothecontrolofdischargesmayformpartofotherdecisionmakingprocesses.Suchexchangeofinformationshouldincludeconsiderationofsocietalaspects,forexamplepublicconcernovertherisksassociatedwithradiationexposure,andconsiderationofthedosestothepublicthatmightresultfromdischargesduringoperation.3.6.2ReviewandAssessmentThroughoutthesafetyreview,theTaskForcecarefullyconsideredhowtheGovernmentofJapan,andTEPCO,involvedinterestedpartiesintheiractivitiesandplanningforthedischargeofALPStreatedwater.Ingeneral,theTaskForceusedtheissuanceoftheBasicPolicybytheGovernmentofJapanasthestartingpointforconsiderationofthistopic,butwhenavailable,theTaskForceappreciatedadditionalmorehistoricaldataprovidedbyMETI,TEPCO,orNRAthatwouldhelptoprovideusefulbackgroundinformation.METIprovidedanoverviewoftheprimarymeansthroughwhichMETI,MOFA,andTEPCOengagewithinterestedparties.TheseincludebriefingsessionsfordiplomaticmissionsinTokyo(morethanahundredsuchsessionshadbeenheldsince2011),bilateralinteractionsthroughvariousformsofcommunicationwithotherGovernmentsorauthorities,includingthoseofneighbouringcountriesandregions,conductofsitetours,presentationsattechnicalconferences,publicreportsthatdetailtheprogressofthesitedecommissioningandpresentationofenvironmentalmonitoringresults,publishinginformationininternationalperiodicalstoensurethepublicismadeawareofdevelopments.METInotedthattheGovernmentofJapanhasbeenengagingwiththepublicontheissueofhandlingALPStreatedwaterformanyyears;however,thepasttwotothreeyearshaveseenmanyopportunitiestosharerelevantupdatesanddevelopmentswithinterestedparties.METIalsonotedthatsomeoutreachto96neighbouringcountrieshasbeenconductedinthenativelanguageofthosecountriestofacilitateabetterunderstandingandexchangeofviews.METIfurtherhighlightedthatowingtointensecommunicationeffortsoverthepast10years,thepublicisreasonablyfamiliarwithsafetyconceptsandhowtheserelatetothedecommissioningoftheFukushimaDaiichiNuclearPowerStation.However,morenuancedconceptssuchasriskreductionandoptimizationofdecommissioning,whicharealsorelevanttothehandlingofALPStreatedwater,arestillnotwidelyunderstoodbythegeneralpublic.TheTaskForcenotedthattheinvolvementofinterestedpartiescanimprovetheunderstandingofthecharacteristicsoftherepresentativepersonandtheacceptabilityofresultingestimateddosewithsite-specifichabitdataprovidedbyrelevantinterestedparties,andthatinvolvementofinterestedpartiesisseenasanimportantinputtotheoptimizationprocess.TheTaskForcealsonotedthatthelong-termnatureoftheproposeddischargecouldpresentuniqueordifferentcommunicationneedsandTEPCOcouldconsiderelaboratingaplantodescribetheinvolvementoftheinterestedpartiesthroughoutthedurationoftheproject.Inparticular,theTaskForcestressedtheimportanceofmaintainingawarenessofchangesinthelocalarea(e.g.,useoftheland)andpopulationhabitsasthatcouldhaveadirectimpacttotheassumptionsintheREIAandthedefinitionoftherepresentativeperson.TheTaskForcealsohighlightedthecriticalroleofaregulatorybodyinensuringinterestedpartiesareinvolvedandtheirviewsconsideredaspartoftheauthorizationprocess.Throughoutthereview,theNRAprovidedperiodicupdatesoftheirprogressandhowtheinvolvementofinterestedpartieswasfactoredin.Thisprimarilyconsiderstwodifferentapproaches:1)publiccommentperiodsforkeyregulatorydocumentsandmilestones,and2)outreachandengagementactivitiesconductedspecificallybytheregulatorybodyforinterestedpartiesinlocal,national,andinternationalsettings.TheNRAprovidedanoverviewoftheactionsundertakenforpubliccommunicationandinvolvementofinterestedparties.TheNRAhighlightedthattheirmainmessagetothepubliconALPSTreatedWaterDischargeis:“ALPStreatedwaterdischargedoesnothavesubstantialadversaryeffectstohealthandtheenvironmentasfarassatisfyingtheregulatoryrequirementsanditisnecessarytoprogressthedecommissioningoftheFDNPS.”AfterTEPCOsubmittedamendmentstotheirimplementationplantofacilitatethedischargeofALPStreatedwateratFDNPS,theNRAandTEPCOhavebeenparticipatinginregularreviewmeetingstodiscussTEPCO’splan.Thesereviewmeetingsareopentothepublic,bothforin-personattendanceandviaweb-streaming.Allmaterials,includingtheminutesofthemeetings,arepostedontheNRAwebsite,andarealsomadeavailableinEnglish.TheNRAexplainedthattheyintendtopublishthedraftresultoftheirreview,solicitpubliccommentsandreflectsuchcommentstothedraftasappropriate.Morespecifically,thedraftresultswillbepostedontheGovernmentwebsiteinJapanese,andtheEnglishversionwillalsobeprovidedforreference.Theperiodforreceivingcommentsfromthepublicisgenerallysetatonemonth.ForthefirstreviewoftherevisedImplementationPlan,asanexample,theNRAnotedthatthereviewresultswereavailablefor30daysandafterthisperiodclosedtheyreport1,233receivedcomments.AspartofitssecondmissiontoNRA,theTaskForcerequestedfurtherinformationabouthowthepubliccommentsarehandled.NRAnotedthattheyarefirstreviewedfortechnicalrelevancetothetopicathand(i.e.,dischargeofALPStreatedwater)thenfurtherorganizedintokeytopicsandduplicatecomments/questionsarecondensed.TheNRAissueditsregulatoryapprovaloftherevisedImplementationPlanon10May2023onlyafterfullyconsideringthefeedbackreceived.TheNRAhighlightedtotheTaskForcetheircommunicationframeworkatthenationallevelthatconsistsofthefollowingcomponents:•LocalgovernmentmeetingsheldinprefecturesaroundFukushima;97•ExplanationsprovidedtopoliticalpartiesandinterestedgroupsaftertheadoptionoftheBasicPolicy;•Nationaldiet7sessionswherethestatusofNRA’sreviewandfuturescheduleshavebeenraised;•Regularpressconferencesfortheprovisionofupdatedinformationtothepublic;•NRA’swebsitewhereNRApoststhematerialsandminutesofthereviewmeetings.Attheinternationallevel,theNRAhasheldmeetingswithothercountriesandorganizationsandexplainedtheup-to-datestatusaroundtheALPStreatedwaterdischarge.TheNRAhasprovidedandindicatedtheirwillingnesstocontinuetoprovideinformationtoneighbouringstatesasappropriate,includingthroughtheframeworkforcooperationamongregulatorybodies,andtheNRAresponsetoquestionssubmittedbyothercountries.TheTaskForcecommentedpositivelyontheeffortsundertakenbytheNRAandnotedthattheNRAisfollowingacomprehensiveapproachintheircommunicationwithinterestedparties.InfutureengagementstheTaskForcenotedtheimportanceof:•Usingappropriatelanguageandpresentationmeanswhencommunicatingwiththepublic.•ClarifyingthedifferenceinrisksassociatedwithALPStreatedwaterdischargefromthoseassociatedwithoveralldecommissioningofthesite.•EnsuringthattheactionsundertakenbytheNRAarepresentedinanopenandtransparentmannerandcanbereviewedbyinterestedpartiesinthefuture.3.6.3ConclusionsTheIAEAhasconcludedthattheactivitiesandapproachtakenbyTEPCOandNRAareconsistentwiththerelevantinternationalsafetystandardsincludedunderthissectionofthereport.Furtherdetailedfindingsareincludedbelow:•Theapproachesforengagementwithlocal,nationalandinternationalinterestedpartieswilldiffer,howevertheneedtoaddresstheviewsofinterestedpartiesovertheentirelengthoftheproposeddischargewillremainanimportantfactorforsustainability.•TheidentificationofinterestedpartiesbytheGovernmentofJapan,andTEPCO,wasconductedinsuchawaytoensurethatawiderangeofinterestedpartieshavebeenincludedintheassociatedoutreachandcommunicationefforts.•TheGovernmentofJapan,TEPCO,andNRAhaveprovidedinformationtoandengagedinconsultationswiththepartiesthatareaffectedbytheplanneddischargeofALPStreatedwater.Thisincludesbothinternational,anddomestic,interestedparties.•TheinvolvementofinterestedpartiesinthedomesticregulatoryauthorizationprocessmanagedbyNRAhasbeenclearlydemonstrated.•TEPCOandMETIhaveconductedsignificantoutreachactivitiestoensuretransparency.7TheNationalDietisJapan’sbicamerallegislatureanditisthehighestorganofStatepower.983.7.OccupationalRadiationProtection3.7.1BackgroundControl,monitoring,assessmentandrecordingofoccupationalexposureareessentialforpropermanagementofradiationprotectionofworkersinanyworkplace.GSRPart3[8]setsrequirementsapplicabletotheregulatorybodyaswellastoregistrantsorlicensees.Theserequirementsincludetheestablishmentofdoselimitsforworkers,optimizationofprotectionandsafetyofworkers,includingdoseconstraintsappliedtooccupationalexposurecontrolinplannedexposuresituationsthroughalicensingprocess.OccupationalradiationprotectionhasastrongoperationalemphasisandGSRPart3alsosetsrequirementsforestablishingandmaintainingorganizational,proceduralandtechnicalarrangementsforthedesignationofcontrolledareasandsupervisedareas,forlocalrulesandformonitoringoftheworkplace,inaradiationprotectionprogrammewithnecessaryguidanceprovidedbyGSG-7[23].Paragraph5.3ofGSG-7statesthat:“Contaminationofareascanarisefromfacilitiesandactivitiesthataresubjecttoregulatorycontrolintermsoftherequirementsforplannedexposuresituations,asaresultofauthorizedactivitiessuchasdischarges,themanagementofradioactivewasteanddecommissioning.Anexposuresituationresultingfromsuchcontaminationiscontrolledaspartoftheoverallpracticeandis,therefore,aplannedexposuresituationandnotanexistingexposuresituation.”TheresponsibilitiesoftheregulatorybodyspecifictooccupationalexposureinplannedexposuresituationsarelaidoutinRequirement19andparas3.69–3.73ofGSRPart3[8].Theregulatorybodyisrequiredtoestablishandenforcerequirementstoensurethatprotectionandsafetyisoptimizedandisrequiredtoenforcecompliancewiththeapplicabledoselimits.Further,theregulatorybodyisresponsiblefortheestablishmentandenforcementofrequirementsforthemonitoring,recordingandcontrolofoccupationalexposuresinplannedexposuresituationsinaccordancewiththerequirement25ofGSRPart3[8],andforthereviewofmonitoringprogrammesofregistrantsandlicensees.Requirement21ofGSRPart3[8]statesthat:“Employers,registrantsandlicenseesshallberesponsiblefortheprotectionofworkersagainstoccupationalexposure.Employers,registrantsandlicenseesshallensurethatprotectionandsafetyisoptimizedandthatthedoselimitsforoccupationalexposurearenotexceeded.”Inplannedexposuresituations,employers,registrantsandlicenseesareresponsibleforensuringthatappropriateradiationprotectionprogrammesareestablishedandimplementedinaccordancewiththerequirement24ofGSRPart3[8],includingorganizationofradiationprotection(management),radiationdoseandmedicalsurveillanceofoccupationallyexposedworkers(radiationworkcategories&surveillance),areaandzoningbasedonradiationexposureconditions/pathways,workpermit,training,proceduresandcontrolarrangements.Requirement22ofGSRPart3[8]statesthat:“Workersshallfulfiltheirobligationsandcarryouttheirdutiesforprotectionandsafety.”Thisrequirementreflectsthatworkerscanbytheirownactionscontributetotheprotectionandsafetyofthemselvesandothersatwork.Forcontractorsprovidingspecializedservices(inthecaseofALPS,entireoperationisconductedbycontractors),legislativearrangementsarerequiredforemployerstoensurethatworkersofcontractors,includingsubcontractors,areprovided99withthenecessaryinformationonradiologicalcharacteristicsoftheworkplaceandthemanagementoffacilitiesshouldensurethatcontractorscarryoutworkwithcompetentpersonnel.InaccordancewiththeGSRPart3[8]andGSG-7[23],specialattentionshouldbegiventotheestablishmentandmaintenanceofanationaldoseregistryasacentralpointforthecollectionandmaintenanceofdoserecords.Thestorageofinformationatthenationaldoseregistryshouldbedesignedtoallowworkers,duringandaftertheirworkinglife,toretrieveinformationonthedosestheyreceivedwhilebeingoccupationallyexposed.CoordinationofdifferentauthoritieswithresponsibilitiesforsafetywithintheregulatoryframeworkincludingsafetyofworkersisrequiredbyGSRPart1(Rev.1)andarrangementsforprotectionofworkersisconsideredintheprocessofapplyinggradedapproachtoreviewandassessmentofthefacilityoractivity[14,8].Radiationprotectionofworkersisonlyoneelementinensuringtheoverallhealthandsafetyofworkersandshouldbeestablishedandimplementedinclosecooperationwiththoseresponsibleforotherareasofhealthandsafetysuchasindustrialhygiene,industrialsafetyandfiresafety(para3.50ofGSG-7[23]).3.7.2IAEAReviewandAssessmentArrangementsundertheRadiationProtectionProgrammeTheNuclearRegulationAuthority(NRA)andtheMinistryofHealth,LaborandWelfare(MHLW)aretheprimarygovernmentalauthoritiesresponsiblefortheimplementationofthelegislativerequirementsconcerningoccupationalexposurethrough“theReactorRegulationAct”(whichincludesprovisionsfortheestablishmentofcontrolledareas,measuringandrecordingofairdoseratesofcontrolledareas,measurestocontrolexposureofradiationworkersandspecialeducation)and“theIndustrialSafetyandHealthAct”(whichincludesprovisionsformedicalexaminationsanddeliveringexposurerecordstothedesignatedinstitution),respectively.TheNRAdescribedtheirroleduringtheMarch2022missionintheestablishmentofdoselimitsforoccupationalexposure,andalsointheapprovalofanoperationalsafetyprogramme(includingarrangementsformonitoringandrecordingofoccupationalexposures).TheNRAexplainedthatoptimizationoftheradiationprotectionofworkersatFukushimaDaiichiNuclearPowerStation(FDNPS)isconductedusingdoselimitsandconcentrationlimitsforradioactivematerialsintheairinhaledbyworkerswithlimitsprescribedbytheNRA.TheTokyoElectricPowerCompany(TEPCO)explainedduringthefirstmissionthattheentiresiteisdesignatedasacontrolledareaandarrangementsareinplaceforindividualandworkplacemonitoringofoccupationalexposureaccordingto“theRadiationControlledAreaMeasuringGuide”and“theGuideforManagementofSetting,ReleasingandChangingofControlledAreasandManagedAreas”.RadiationProtectionProgramme(RPP)Registrantsandlicenseesareresponsibleforprotectionandsafety.Theseresponsibilitiesincludetheperformanceofanappropriatesafetyassessmentandtheestablishmentandmaintenanceofasystemofprotectionandsafetytoprotectworkersagainstexposure.TheRPPforoccupationalexposure,whichisacombinationofgooddesign,highqualityconstructionandproperoperation,primarilyincludes,asappropriate(Paragraph3.60ofGSG-7):100a)Themaintenanceoforganizational,proceduralandtechnicalarrangementsforthedesignationofcontrolledareasandsupervisedareas,forlocalrulesandformonitoringoftheworkplace;b)Theassessmentandrecordingofoccupationalexposure;c)Workers’healthsurveillance;d)Provisionofadequateinformation,instructionandtraining.References:[8;24]AssessmentandRecordingofOccupationalExposureandWorkers’HealthSurveillanceSpecifictoALPStreatedwaterdischargefacility,occupationalexposuresareassociatedwiththeconstruction,operationandmaintenanceofsystemsrequiredforthedischarge.TEPCOexplainedintheNovember2022missionthatallworkersenteringthemanagementareaofFDNPS(theentiresiteisconsideredacontrolledarea)arerequiredtousepersonalprotectiveequipment(PPE)andindividualpassive/activedosimetersprovidedbyauthorizedtechnicalserviceprovidersoperatedunderaqualitymanagementsystem,regardlessofthemagnitudeoftheexposure.Additionally,allworkersaremonitoredperiodicallybyin-vivoradiobioassayforinternalexposuredueto137Cs,usingawholebodycounterwithplasticscintillationdetectors.Nasalcavitysamplingandmonitoringfor90SrisconductedatFDNPS,andasoftwarecalled“MonitoringtoDoseCalculation”(MONDAL)isusedforinternaldoseassessment.TEPCOprovidedinformationontheindividualmonitoringprogrammeforexposuresfromintakesofradionuclideswhichisconductedforidentifiedworkerswhoareexposedoverrecordinglevelsduetocontaminationaswellasthosewhouserespiratoryprotectiveequipment.TEPCOexplainedthatoccupationalexposuredataforworkers,includingcontractors,isgathered,stored,andmaintainedbyTEPCOandsubmittedtoacentraldatabase.Also,aprogrammeforworkers’healthsurveillanceisconductedintheFDNPS,consistingofmedicalchecksevery6monthswithnecessaryrecordkeepingarrangementsbasedonthe“HealthMonitoringManual”andthe“Long-termHealthcareManual”.TEPCOprovidedinformationexplainingthattherequirementfordoseassessmentandoptimizationappliesonlywherethedosesofworkersarelikelytoexceedcertainlevelsandthereforeonlyasmallproportionoftheworkforcewouldneedtobeassessed.TEPCOwillcarryoutfurtherworkplaceandindividualmonitoringprogrammes,asappropriate,fordoseassessmentpurposesandforprovidingwarningofchangingexposureconditions.TEPCOexplainedthatforallworkconductedinthefacility,thereareradiationcontrolplansinplace,submittedbytheresponsibleorganization(includingcontractors)andvalidatedbyTEPCO.Meetingstodiscussthecontrolofexposureinworkplans(so-called‘ALARA’meetings)areorganizedinadvanceattheplanningstage.Inaddition,TEPCOexplainedthatinternaldosesduetotritiumarelow.TritiumismeasuredasHTOinwaterandthenitsconcentrationintheairisestimated.TEPCOaddedthatallworkerswearappropriatepersonalprotectiveequipmentalthoughexposureduetoinhalationisnotexpected.TheNRAprovideddetailedinformationduringtheJanuary2023missionaboutthebasisforregulatoryoversightwithregardtomonitoringrequirements(e.g.,implementationofinvestigationlevelsandrecordinglevels)throughtheimplementationoftheNRAOrdinanceforFDNPS,andNRANotificationforFDNPS.Regardingoccupationalexposurerecordkeeping,theNRAexplainedthattheRadiationEffectsAssociation(RadiationDoseRegistryCenter,RADREC)istheregistryinstitutionofdoserecordsofradiationworkers(i.e.,nuclearworkers,radioisotopeworkers,anddecontaminationworkers)asstipulatedintheNRAOrdinanceforFDNPS.101MonitoringandrecordingofoccupationalexposureThepersonal(individual)monitoringofworkersforoccupationallyexposedworkersandtherecordingoftheradiationdosesreceivedbyworkersforproperoccupationalexposurecontrolareimportantaspectsofanyRadiationProtectionProgramme.Paragraph3.105ofGSRPart3statesthat:“Recordsofoccupationalexposureshallinclude:a)Informationonthegeneralnatureoftheworkinwhichtheworkerwassubjecttooccupationalexposure;b)Informationondoseassessments,exposuresandintakesatorabovetherelevantrecordinglevelsspecifiedbytheregulatorybodyandthedatauponwhichthedoseassessmentswerebased;c)Whenaworkerisorhasbeenexposedwhileintheemployofmorethanoneemployer,informationonthedatesofemploymentwitheachemployerandonthedoses,exposuresandintakesineachsuchemployment;d)Recordsofanyassessmentsmadeofdoses,exposuresandintakesduetoactionstakeninanemergencyorduetoaccidentsorotherincidents,whichshallbedistinguishedfromassessmentsofdoses,exposuresandintakesduetonormalconditionsofworkwhichshallincludereferencestoreportsofanyrelevantinvestigations.”GSG-7providesguidanceforthecollection,analysis,anddisseminationofoccupationalradiationexposureinformationintheformofnationaldoseregistryasacentralpointforthecollectionandmaintenanceofdoserecords.OptimizationofoccupationalexposureTheNRAexplainedthatoptimizationoftheradiationprotectionofworkersatFDNPSisconductedusingdoselimitsandconcentrationlimitsforradioactivematerialsintheairinhaled.SomeTaskForcemembershighlightedthatthereisnosinglewaytoimplementoptimizationofoccupationalexposureandaddedthattheapproachfollowedbytheNRAiswelldocumented.TEPCObenefitsfromtheimplementationofoptimizationofprotectionandtheuseofdoseconstraintsfortheradiationprotectionofworkersinadditiontotheirownlong-termoperationalexperience.TEPCOeffectivelyutilizessafetymeasuressuchastargetvalues,dailydosefollow-ups,andworkpermitsrelatedtoworkplacecharacteristics(includingALPStreatedwaterdischargefacility).OptimizationofprotectionandsafetyForoccupationalexposure,optimizationofprotectionandsafetyshouldbeconsideredatallstagesinthelifetimeofequipmentandinstallations,inrelationtobothexposuresfromnormaloperationsandpotentialexposures.Optimizationisanobligationofmeans,andnotanobligationofresultsinthesensethattheresultofoptimizationdependsonprocesses,procedures,andjudgementsandisnotagivenvalueofdoseorexposure.Theresultofoptimizationdependsonprocesses,procedures,andjudgementsandisnotrepresentedbyagivenvalueforexposure.Paragraph1.23ofGSRPart3[8]statesthat:“…Foroccupationalexposure,thedoseconstraintisatooltobeestablishedandusedintheoptimizationofprotectionandsafetybythepersonororganizationresponsibleforafacilityoranactivity....Afterexposureshaveoccurred,thedoseconstraintmaybeusedasabenchmarkforassessingthesuitabilityoftheoptimizedstrategyforprotectionandsafety...thathasbeenimplementedandfor102makingadjustmentsasnecessary.Thesettingofthedoseconstraintneedstobeconsideredinconjunctionwithotherhealthandsafetyprovisionsandthetechnologyavailable.”3.7.3ConclusionsTheIAEAhasconcludedthattheactivitiesandapproachtakenbyNRAandTEPCOareconsistentwiththerelevantinternationalsafetystandardsincludedunderthissectionofthereport.Furtherdetailedfindingsareincludedbelow:•RelevantregulatoryarrangementsinJapanforoccupationalradiationprotectionareconsistentwiththerelevantinternationalsafetystandards.TheIAEAconfirmsthatNRA’sapproachtoenforcetheoccupationalexposurecontrol,monitoring,assessmentandrecordingissufficient.•TEPCOhasareliableandsustainableradiationprotectionprogramme.TheIAEAobservedclearevidenceofself-regulationbyTEPCOforanadvanceddesignandimplementationofoccupationalexposurecontrolmeasuresandmonitoringarrangementsrelatedtotheoperationofALPStreatedwaterdischargefacility.•OccupationallyexposedworkersworkingatFDNPSincludingworkersinvolvedinactivitiesassociatedwiththeplanneddischargesofALPStreatedwater,regardlessofwhethertheyarecontractorsorstaff,areunderthesameoccupationalradiationprotectionregime.103MONITORING,ANALYSIS,ANDCORROBORATION4.1.OverviewofCorroborationActivitiesTheIAEA’ssafetyreviewofthehandlingofALPStreatedwateratFDNPSincludesthefollowingthreecomponents:theassessmentofprotectionandsafety;thereviewofregulatoryactivitiesandprocesses;andindependentsampling,datacorroboration,andanalysisactivities.ThethirdcomponentisincludedintheoverallsafetyreviewtoprovideconfidenceintheaccuracyofdataprovidedbyTEPCOandtheJapaneseauthorities.Additionally,thesecorroborationactivitiesprovideanotherlayerofassurancethatTEPCOandtheGovernmentofJapanareadheringtorelevantinternationalsafetystandards.TheIAEA’scorroborationwillnotbeexhaustivebutratherisintendedtoallowinterestedpartiestoinfertheaccuracyofalltheavailabledatabyvalidatingthekeydataprovidedbythelaboratoriesinJapanresponsibleforproducingandpublishinganalyticalresultsfromtheALPStreatedwaterdischargeprocess.TheIAEA’scorroborationactivitieswillcomplementthebroadermonitoringandverificationregimethatistheresponsibilityoftheGovernmentofJapanwhomaintainstheoverallresponsibilityforthesafetyofitsnuclearfacilitiesandactivities.TheIAEA’sinvolvementisacriticalelementfordemonstratingtheaccuracyandvalidityofdatabeingreportedbyJapaneseauthoritiesrelatedtothedischargeofALPStreatedwater,andthereforebuildingconfidenceintheoverallIAEAsafetyreview.Currently,theIAEA’sindependentsampling,datacorroboration,andanalysisactivitiesincludethreemajorcomponents:•Sampling,analysisandinterlaboratorycomparisonforALPStreatedwaterfromtheFDNPS.•Sampling,analysisandinterlaboratorycomparisonforenvironmentalsamples(e.g.,seawater,fish)fromthesurroundingenvironmentofFDNPS.•AssessmentofthecapabilitiesofdosimetryserviceprovidersinvolvedinthemonitoringofinternalandexternalradiationexposureofworkersatFDNPS.PART4104CorroborationofSourceandEnvironmentalMonitoringTheIAEAcorroborationofsourceandenvironmentalmonitoringrelatedtodischargesofALPStreatedwaterfromFDNPSiscomprisedofthreedistinctelements(seealsoFigure4.1):•ReviewofsamplingandanalyticalmethodsforsourceandenvironmentalmonitoringrelatedtoALPStreatedwateratFDNPSusedbyTEPCOandrelevantJapaneseauthorities8.•CorroborationofsourcemonitoringundertakenbyTEPCO,includingacomprehensiveradiologicalcharacterizationofALPStreatedwatersamples.•CorroborationofenvironmentalmonitoringundertakenbyTEPCOandrelevantJapaneseauthorities.2.Corroborationofsourcemonitoring1.Reviewofsamplingandanalyticalmethods3.CorroborationofenvironmentalmonitoringCorroborationofexternalexposuremonitoringcapabilitiesCorroborationofinternalexposuremonitoringcapabilitiesReviewofanalyticalmethodsCorroborationofindividualmonitoring+CorroborationofradiologicaldataFigure4.1:AschematicoverviewoftheelementsofthecorroborationbeingundertakenbytheIAEAlaboratoriesandthelinksbetweentheseelements.Thecorroborationofsourceandenvironmentalmonitoringwillbebasedoninterlaboratorycomparisons(ILCs).ILCs,alongwithproficiencytests(PTs),arestandardmethodsforlaboratoriestoassessthequalityoftheirmeasurementresultsincomparisonwiththoseofotherparticipatinglaboratories,andtoidentifyanypotentialimprovements.PTsinvolvetheevaluationofperformanceagainstpre-establishedcriteriawhereasILCsinvolvetheorganization,performanceandevaluationofmeasurementsonthesameorsimilaritemsbytwoormorelaboratoriesinaccordancewithpredeterminedconditions.Forthecorroborationofsourcemonitoring,samplesofALPStreatedwaterthatisconsideredbyTEPCOtobereadyfordilutionanddischarge–pendingfinalconfirmationbyanalyses–arebeingcollectedfromtanksatFDNPS.Forthecorroborationofenvironmentalmonitoring,samplesofseawater,sedimentandmarinebiotaarebeingcollectedfromlocationsontheeastcoastofJapanaroundFDNPS.Samplecollectionandpre-treatmentactivitiesundertakenbyTEPCO,andrelevantJapaneseauthoritieswillbefacilitatedandobservedbytheIAEA.Thehomogeneityofallsampleswillbeensured.Thesesampleswillbesplit,andsub-sampleswillbeprovidedtothelaboratoriesparticipatingintheILCsfortheanalysisoftheactivityconcentrationsofarangeofrelevantradionuclides.CorroborationofOccupationalRadiationProtectionAnindividualmonitoringprogrammeisdesignedtoassessradiationdosestoworkersarisingfromexposureduetoexternalsourcesofradiationandfromexposureduetointakesofradionuclides.TheIAEA’scorroborationforoccupationalradiationprotectioncapabilitiesiscomprisedofthreedistinctelements(seealsoFigure4.2):8TEPCOhassoleresponsibilityforsourcemonitoringatFDNPS.AllenvironmentalmonitoringrelatedtothenuclearaccidentatFDNPSisconductedaccordingtotheComprehensiveRadiationMonitoringPlan(CRMP).TEPCOandotherrelevantJapaneseauthoritieshaveresponsibilitiesundertheCRMP.Inpractice,samplingandanalysisareoftencarriedoutbycontractedlaboratories.WithinthisreportitisassumedthatTEPCOandtheotherrelevantJapaneseauthoritiesasdefinedintheCRMPhaveresponsibilityforreportingtheresultsofthemonitoringforwhichtheyareresponsible.However,theparticipantsintheILCscouldbethelaboratoriesthathavecontractsinplacetoundertakeanalyses.1051.CorroborationofrelevantJapaneseindividualmonitoringservices(IMS)capabilitiesformonitoringandassessingexternalexposure;2.CorroborationofrelevantJapaneseIMScapabilitiesformonitoringandassessinginternalexposure;and3.ReviewofanalyticalmethodsinexternalandinternaldosimetryusedbytherelevantJapaneseIMS.2.Corroborationofsourcemonitoring1.Reviewofsamplingandanalyticalmethods3.CorroborationofenvironmentalmonitoringCorroborationofexternalexposuremonitoringcapabilitiesCorroborationofinternalexposuremonitoringcapabilitiesReviewofanalyticalmethodsCorroborationofindividualmonitoring+CorroborationofradiologicaldataFigure4.2.Schematicoverviewofthecorroborationofindividualmonitoring.First,theIAEAwillcorroboratethecapabilitiesofIMSusedbyTEPCOfortheassessmentofoccupationalexposureofworkersfromexternalsourcesofradiation.Aninterlaboratorycomparison(ILC)willbetheprinciplemeansofaccomplishingthiscorroboration,whichwillfocusonTEPCO’smonitoringprogrammeforassessingtheoccupationalexposureofworkersinvolvedinhandlingALPS-treatedwater.PersonaldosimetrysystemswithintegratedpassivedetectorswillbeprovidedbyandevaluatedattheIAEARadiationSafetyTechnicalServicesLaboratory(RSTSL)andrelevantJapaneseIMS.Irradiationofdosimeterswillbecarriedoutintwophasesforwhole-bodyandextremitydosimeters,respectively,atprimaryorsecondarystandardsdosimetrylaboratories.TheIAEAwillalsoconductareviewofanalyticalmethodsrelevanttoexternaldosimetryusedbytherelevantJapaneseIMS.Theresultsofthisreviewwillcontributetoensuringthevalidityofthedatageneratedaspartoftheabove-mentionedILC.Second,theIAEAwillcorroboratethecapabilitiesofIMSusedbyTEPCOfortheassessmentofoccupationalexposureofworkersduetointakeofradionuclides.AnILCwillbetheprinciplemeansofaccomplishingthiscorroborationforin-vitroandin-vivoradiobioassayandwillfocusonTEPCO’scapabilitiestodetectradionuclideactivitiesinurinereferencesamplesandinphantomsemulatingthehumanbody.Inthefirstphase,urinereferencesampleswillbepreparedbyaccreditedlaboratoriesanddistributedforcomparativeanalysisattheIAEARSTSLandrelevantJapaneseIMS.Inasecondphase,asolid,leak-proofslicedbottlemannequinabsorption(BOMAB)phantomcontainingexemptlaminatedplanarradionuclidesourcesinsertedbetweenlayersofpolyethylenewillbemeasuredatbodycountersinFukushimaDaiichiandatIAEAHeadquartersinaround-robintest.TheIAEAwillalsoconductareviewofanalyticalmethodsrelevanttointernaldosimetryusedbytherelevantJapaneseIMS.Theresultsofthisreviewwillcontributetoensuringthevalidityofthedatageneratedaspartoftheabove-mentionedILC.ParticipatingLaboratoriesTheIAEAwillinvolveseveralofitsownlaboratoriesandthird-partylaboratoriesaspartofthesecorroborationactivities.AlistoftherelevantIAEAlaboratoriesisincludedbelow:•IAEAMarineEnvironmentLaboratories,RadiometricLaboratory(RML),Monaco.TheRadiometricsLaboratory(RML)inMonacofostersexpertiseinmarineradioactivitymeasurement,monitoringandassessmentandintheapplicationofradiotracersformarinepollution,climatechangeandoceanographicstudies.RMLoperatesspecialisedradiochemistry106laboratoriesandanundergroundcountingfacilityfortheanalysisoflowlevelsofradionuclidesinmarineandatmosphericsamplesandenvironmentalforensicsapplications.Thelaboratorymaintainsanopenaccessmarineradioactivitydataportal(MARIS[24])andassistsMemberStatestopreparefornuclearandradiologicalincidentsoremergenciesthatcouldimpactthemarineenvironment.BysupportingdataqualityinMemberStatesforanalysesofradionuclidesinseawater,sedimentandmarinebiota,includingthroughproductionofreferencematerialsaccordingtoanaccreditedqualitysystemandPTsandILCs,RMLcontributestothecredibilityofmonitoringandresearchresults.•IAEATerrestrialEnvironmentalRadiochemistryLaboratory(TERC),Seibersdorf,Austria.TheTerrestrialEnvironmentalRadiochemistry(TERC)laboratoryinSeibersdorf(Austria)assistsMemberStatesinassuringthequalityofperformedanalyticalworkbysupportingrespectivelaboratoriesactiveinthefieldsofenvironmentalradioactivity,stableisotopeandtraceelementanalysis.TERCprovidestechnicalsupporttoMemberStatelaboratoriesbyprovidingsuitablecertifiedreferencematerialsforcalibrationandqualitycontrol,byorganisingPTstofacilitatechecksofanalyticalquality,byprovidingthoroughlytestedandpublishedanalyticalmethods,andbytraininglaboratoriesintheirsetupandoperation.•IAEAIsotopeHydrologyLaboratory(IHL),Vienna,Austria.TheIsotopeHydrologyLaboratory(IHL)inViennaprovidesanalyticalservices,training,andexperttechnicaladvicetoMemberStatestodeveloptheirownanalyticalfacilitiesandtohelpensurethequalityofisotopemeasurementsconductedintheirlaboratories.TheIHLhousesstate-of-the-artanalyticalequipmentforthecollectionandmeasurementofstableandradiogenicisotopesandnoblegasesfromwaterandhydrologicalsamplesandprovidesanalyticalsupporttotheIAEA’sWaterResourceProgramme’sglobalhydrologymonitoringnetworks,includingtheglobalnetworkofisotopesinprecipitation(GNIP),andtheglobalnetworkofisotopesinrivers(GNIR).IsotopicdataproducedbytheIHLareincludedintheGNIPandGNIRdatabases,andaremadeavailablecost-freetoMemberStatesviatheinternet.•IAEARadiationSafetyTechnicalServicesLaboratory(RSTSL),Vienna,Austria.TheRadiationSafetyTechnicalServicesLaboratory(RSTSL)providesradiationprotectionservices,includingindividualmonitoringofworkers(e.g.,IAEAstaff)foroccupationalexposureduetoexternalandinternalsourcesofradiation.Since2006,RSTSLholdsaccreditationtoISO/IEC17025[21],demonstratingthetechnicalcompetenceandtheimpartialityofthelaboratoryinprovidingvalidresults.UnderthecoordinationoftheparticipatingIAEAlaboratories,selectedthird-partylaboratories,membersofthenetworkofAnalyticalLaboratoriesfortheMeasurementofEnvironmentalRadioactivity(ALMERA)withdemonstrablecompetenceinthemethodsrequired,arealsoconductinganalysesofsamplesasparticipantsintheILCs.ALMERAisanetworkcomprising190memberlaboratoriesgloballythatiscoordinatedjointlybyRMLandTERC.Itprovidesaplatformformaintaininganddevelopingcapabilityonthedeterminationofradionuclidesinair,water,soil,sedimentandvegetationthatcanbeusedforbothroutineandenvironmentalemergencymonitoringintheIAEAMemberStates.1074.2.UpdateonCorroborationofSourceMonitoringForthefirstILCundertheIAEA’sALPSsafetyreview,theALPStreatedwatersamplesweretakeninMarch2022fromtheK4-BtankgroupatFDNPS.ThewatercontainedintheK4-BtankgroupisexpectedtobethefirstbatchofALPStreatedwaterthatwillbedischarged,onlyonceTEPCOreceivesallregulatoryapprovalsfromNRA.ThefocusoftheanalysiseffortsforthisILCwereontheradionuclidesinthesourcetermwhichareincludedintheradiologicalenvironmentalimpactassessmentconductedbyTEPCO.Participatinglaboratorieswerealsoencouragedtoanalyseforadditionalradionuclidesbeyondthesourceterm.AnalyseswereundertakenbyTEPCOandbythefollowingthreeparticipatingIAEANuclearSciencesandApplicationsLaboratories:•IAEAMarineEnvironmentLaboratories,RadiometricsLaboratory(RML),Monaco;•TerrestrialEnvironmentalRadiochemistryLaboratory(TERC),Seibersdorf,Austria;•IsotopeHydrologyLaboratory(IHL),Vienna,Austria.Additionally,underthecoordinationoftheparticipatingIAEAlaboratories,selectedthird-partylaboratories,membersofthenetworkofAnalyticalLaboratoriesfortheMeasurementofEnvironmentalRadioactivity(ALMERA)withdemonstrablecompetenceinthemethodsrequired,alsoconductedanalysesofsamplesasparticipantsintheILCs.ThelaboratoriesparticipatinginthisILCwere:•SpiezLaboratory(LS–LaborSpiez),Switzerland•InstitutdeRadioprotectionetdeSûretéNucléaire(IRSN),France•LosAlamosNationalLaboratory(LANL),UnitedStatesofAmerica•KoreaInstituteofNuclearSafety(KINS),RepublicofKoreaTheresultsoftheanalysesundertakenateachlaboratorywerereportedtotheIAEA.Forresultsthatcouldbeintercompared(i.e.,forradionuclidesforwhichactivityconcentrationsabovedetectionlimitswerereportedbyatleasttwolaboratories)astatisticalevaluationtoassessagreementwascarriedoutbytheIAEA.ThemethodusedforthestatisticalevaluationwasbasedontechniquescurrentlyusedbytheInternationalBureauofWeightsandMeasures’(BIPM)ConsultativeCommitteeforIonizingRadiation,SectionII:MeasurementofRadionuclides,CCRI(II)and,thus,adheredtobestinternationalpractice.Forotherradionuclides,thedetectionlimitsreportedbyparticipatinglaboratorieswerecomparedtoevaluatewhethertheanalyticalmethodsusedbyTEPCOwerebroadlyequivalentandthusappropriateandfitforpurpose.On31May2023theIAEApublishedadetailedreportincludingtheresultsfromthisILC[1].Theresultsarepresentedintablesandchartsinthisreport.Referenceismadetotherelevantregulatorylimitfordischargetoseaforeachradionuclideasappropriate.ThekeyfindingsofthisILCare:•TEPCOhasdemonstratedahighlevelofaccuracyintheirmeasurementsandtechnicalcompetence.•TEPCO’ssamplecollectionproceduresfollowtheappropriatemethodologicalstandardsrequiredtoobtainrepresentativesamples.•TheselectedanalyticalmethodsutilizedbyTEPCOfordifferentradionuclideswereappropriateand108fitforpurpose.•NeithertheIAEA,northeparticipatingthird-partylaboratories,detectedanyadditionalradionuclides(i.e.,radionuclidesbeyondwhatisincludedinthesourceterm)atsignificantlevels.Inthereport,theIAEAnotesthatthesefindingsprovideconfidenceinTEPCO’scapabilityforundertakingaccurateandprecisemeasurementsrelatedtothedischargeofALPStreatedwater.Furthermore,basedontheobservationsoftheIAEA,TEPCOhasdemonstratedthattheyhaveasustainableandrobustanalyticalsysteminplacetosupporttheongoingtechnicalneedsatFDNPSduringthedischargeofALPStreatedwater.InOctober2022,theIAEAwitnessedthecollectionoftwoadditionalbatchesofsamplesofALPStreatedwater.ThesesamplesarebeingusedinthesecondandthirdILCstosupportthecorroborationofsourcemonitoring.ThesampleswerecollectedfromtheG4S-B10andtheG4S-C8tanks.IncontrasttothesamplescollectedforthefirstILCforthecorroborationofsourcemonitoring,thesearestandardtanksforstorageofALPStreatedwaterandnotinterconnectedorsubjecttocirculationandagitation.Toensureinter-samplehomogeneityineachcase,ALPStreatedwaterwasfirsttransferredtoa300Lplastictank,thentoasecond300Lplastictankand,finally,backtothefirst300Lplastictank.Samplecontainers(3L)werethenfilledandpreparedforshippingtoeachparticipatinglaboratory.ThesamplevolumewassmallerforthesecondandthirdILCsasrobustnesstestingwillnotbecarriedoutforthesesamples,havingalreadybeencompletedfortheearliersamples.AswellasTEPCOandtheIAEAlaboratories,theALMERAlaboratoryKoreaInstituteofNuclearSafety(KINS)willparticipateintheseILCs.TheIAEA’ssampleswerereceivedbyTERCinNovember2022.KINSalsoreceiveditssamplesininNovember2022.Areportincludingtheanalysisofthesesamplesisexpectedtobepublishedlaterin2023.4.3.UpdateonCorroborationofEnvironmentalMonitoringInNovember2022theIAEAparticipatedinasamplingmissioninJapantocollectenvironmentalsamples(e.g.,seawater,marinesediment,fish,seaweed)forthefirstILCtocorroborateenvironmentalmonitoringrelatedtodischargesofALPStreatedwater.ThesesampleswerecollectedjointlywithexpertsfromJapanaccordingtomethodsmirroringexistingsamplingpracticesutilizedbytheIAEAforILCsorganizedwithintheprojectNA3/38(MarineMonitoring:ConfidenceBuildingandDataQualityAssurance)overthepastnineyears.ParticipatinglaboratorieshavebeeninstructedtosubmitresultsaccordingtoasimilarprotocoltothatusedforthefirstILCforthecorroborationofsourcemonitoring.Followingtheevaluationofallsubmitteddata,theresultsoftheILCwillbemadeavailablebytheIAEAinthesecondhalfof2023.TheresultsoffuturemonitoringofenvironmentalsampleswillbecomparedagainstthisbaselinetoassessanymeasurableimpactsfromthefuturedischargesofALPStreatedwater.1094.4.UpdateonCorroborationofOccupationalRadiationProtectionTheresultsfromthefirstILCforoccupationalradiationprotectionwillbeavailablelaterin2023.ThisfirstILCwillfocusonexternaldosimetryforwhole-bodyexposure,whereasfutureILCsforoccupationalradiationprotectionwillfocusonexternaldosimetryforextremityexposureandinternalmonitoringforradionuclideintakes.ILCsforoccupationalradiationprotectionwillbeconductedbetweentheIAEA’sRadiationSafetyTechnicalServicesLaboratoryandtheindividualmonitoringservicesusedbyTEPCOforFDNPSworkers.Inthefirsthalfof2023,theIAEAinitiatedthecorroborationforexternaldosimetry.TheIAEAhasissuedacontracttoasecondarystandardsdosimetrylaboratorytohavedosimetersirradiatedunderreferenceconditionsinsupportofthecorroborationofexternaldosimetry.TheirradiateddosimeterswillthenbereturnedtorelevantJapaneseIMSandtheIAEA’sRSTSLforanalysis.AftertherelevantJapaneseIMSandRSTSLhavecompletedtheiranalysisinthesecondhalfof2023,theIAEAwillcollectandanalysetheresults.TheIAEAwillcollecttheresultsfromallparticipatinglaboratoriesandconductascreeningtoensurethatalllaboratorieshavesubmittedacompleteassessmentpackagewithallnecessarydocumentation.TheIAEAwilldraftareporthighlightingtheresults,whichwillbepublishedbytheendof2023.Furthermore,inthesecondhalfof2023,theIAEAwillinitiatethestepstoconductthecorroborationforin-vitroandin-vivointernalmonitoring.TheIAEAwillidentifyvendorsfortheurinesamplesspikedwithcertifiedreferencematerialsandwillshiptheurinesamplesforin-vitroandareferencephantomforin-vivobioassaytoTEPCOaspartoftheILC.RSTSLwillalsoconductanalysesofthespikedurinesamplesandthephantomthroughout2024.110111FUTUREACTIVITIESAsnotedpreviously,thiscomprehensivereportisasynthesisofnearlytwoyearsofworkbytheIAEATaskForceandincludesexplanationsandinsightsoverabroadrangeoftopicsthatareimportanttounderstandingtheoverallsafetyofthisprocess.ThepurposeofthiscomprehensivereportistopresenttheIAEA’sfinalconclusionsandfindingsofthetechnicalreviewtoassesswhethertheplannedoperationtodischargetheALPStreatedwaterintothePacificOceanoverthecomingdecadesisconsistentwithrelevantinternationalsafetystandards.However,onceanydischargesbegin,manyofthetechnicaltopicsreviewedandassessedbytheTaskForcewillneedtoberevisitedatvarioustimestoassesstheconsistencyofactivitiesduringtheoperationoftheALPStreatedwaterdischargeswithrelevantinternationalsafetystandardsSofar,thefocusoftheIAEA’sreviewhasbeenonensuringconsistencywithwithrequirementsintheinternationalsafetystandardsthatapplyduringthepre-operationalphaseoftheplanneddischargeofALPStreatedwater(i.e.,priortobeginningthewaterdischarges).However,inthecomingmonthstheTaskForcewillshiftitsfocustorequirementsfortheoperatorortheregulatorybodythatcanonlybeassessedduringoperations.Additionally,theTaskForcehasnotedthatmanyofthesetechnicaltopicsthatarebeingassessedbeforeoperationsbegin,shouldalsobereviewedperiodicallyinthefuturetoensurecontinuedconsistencywiththerelevantinternationalsafetystandards.Regardingfutureactivities,afterthepublicationofthisreport,theIAEAwillcontinueimplementingitssafetyreviewusingtheoverallthreeelementshighlightedbelow.ComponentsofIAEA’sReviewAssessmentofProtectionandSafety•ReviewTEPCO’simplementationplanandsupportingdocumentation.•Focusontechnicalconsiderationssuchassourcecharacterization,safetyrelatedaspectsoftheapproach,occupationalradiationexposure,radiologicalenvironmentalimpactassessment.RegulatoryActivitiesandProcess•ReviewNRAactionsandprocessesrelevanttotheproject•Focusonsafetyobjectives,regulatoryrequirements,regulatoryassessment,regulatoryinspections.IndependentSampling,DataCorroborationandAnalysis•IndependentsamplingandanalysistocorroboratedatafromJapan.•Performanalysisofsourcetermandenvironmentalsamples.•Corroboratemonitoringresultsforoccupationalexposure.Figure5.1ComponentsoftheIAEAreviewPART5112Additionally,theIAEAhasestablishedapresenceattheFDNPSwiththeestablishmentofanIAEAsiteoffice.IAEAexpertswillmaintainaconstantpresenceonsiteforanumberofweeksbeforeandaftertheplanneddischargesofALPStreatedwater.Outsideofthistimeframe,theIAEAexpertswillbeonsiteformajoractivitiesandwillconductingmonitoringasneeded.5.1.ReviewMissionsForthefirsttwoelements,namelytheassessmentofprotectionandsafety,andregulatoryactivitiesandprocesses,theIAEAwillutilizeasimilarmodelofconductingperiodicreviewmissionstoJapanusingtheTaskForcemodelwithtechnicalexpertsfromtheIAEASecretariatandindependentexternalexperts.However,unlikeinthepast,futurereviewmissionswillbecombinedgiventhestrongconnectionbetweentechnicalandregulatorytopics.ThesefuturereviewmissionswillbeguidedbythemaintechnicalconsiderationsthatarehighlightedinPart3ofthisreport.BelowisalistofexampletopicsthatwillbereviewedbytheTaskForceinduecourse,afterthedischargesofALPStreatedwaterhavebegun.RegulatoryControlandAuthorization•NRA’sapproachtoencourageoptimizationofprotectionandsafetyduringfuturereviewsoftheauthorization.•NRA’sapproachtoreviewingandpotentiallyrevisingdischargelimitsinresponsetoTEPCO’songoingoptimisationofprotectionandsafety.•NRA’sapproachtoidentify“unusualvalues”andrefineactionlimitsbasedonincomingenvironmentalmonitoringdataandotheroperationalexperience.SafetyRelatedAspectsofSystemsandProcessesforControllingDischarges•TheimplementationofmaintenanceplansforthevariousequipmentandstructuresthatmakeuptheALPSdischargeprocess.•Operationalorenvironmentalchangesthatwouldrequireareassessmentofthesafetyandpotentiallythechangeofanyengineeredaspectsoftheprocess.•IdentificationandreviewofanyabnormaloccurrencesandthesubsequentactionstakenbyTEPCOandtheirinteractionswithNRAconsistentwithdomesticregulatoryrequirements.CharacterizationoftheSource•TEPCO’sandNRA’sreviewofthesourcetermas1)thedecommissioningprocessatFDNPScontinuesandastheradionuclidecontentandotherpropertiesofcontaminatedwaterpotentiallychangeand2)theoperationalALPStechnologyatFDNPSpotentiallyevolves.•TEPCO’sconsiderationofchangestothesourcecharacterizationasthesizeoftheALPS-relatedmonitoringdatabase–bothsourceandenvironmental–grows.Thiswillbehelpfulinensuring113thereisastrongconnectionbetweenthecharacterizationofthesourceandenvironmentalmonitoringprogrammes.RadiologicalEnvironmentalImpactAssessment•CheckingwhetherTEPCOandNRAhaveundertakenaperiodicreviewofREIA.•ReviewingTEPCO’sapproachtoupdatingtheREIAifinformationchanges,includingthesourceterm,habitsofthepopulationovertimeandresultsoftheenvironmentalmonitoringindicatethattheREIAresultsneedrevising.•TheTaskForcewillreviewtheimplementationoftheprocessputinplacebytheNRAtoperiodicallyreviewtheauthorizationofthedischargesofALPStreatedwater(seeSection3.1)inthefuture.SourceandEnvironmentalMonitoring•HowfutureresultsfromsourceandenvironmentalmonitoringpublishedbyTEPCO,andbyindependentorganizationsundertheCRMP,arebeingusedtoverifyanddemonstratecompliancewiththedischargeauthorizationandrequirementsforthecontrolofpublicexposures.•Howenvironmentalmonitoringresultsarebeingusedtoverifytheassumptionsmadefortheassessmentofpublicexposureandradiologicalenvironmentalimpacts•ObservationoftheprocessutilizedbytheGovernmentofJapan,NRA,andTEPCOtorespondtoanypotentialabnormalresultsfrommonitoringprogrammes.InvolvementofInterestedParties•TheinvolvementofinterestedpartiesinfurtherregulatorystepsrelatedtotheALPStreatedwaterdischarges.•Theinvolvementofinterestedpartiesinpotentialfuturechangestokeyaspectsofthedischargesuchasthedischargelimitsordesignforthedischarge.•PeriodicupdatesontheActionPlanfortheContinuousImplementationoftheBasicPolicyonHandlingofALPSTreatedWaterasitrelatestotheinvolvementofinterestedparties.•Howinterestedpartiesareinvolvedovertimetoensurethatup-to-datehabitdataisconsideredaspartoffuturereviewsoftheREIAandmonitoringprogrammes.•Informationexchangeandcommunication,asneeded,withtheGovernmentsofneighbouringcountriesthroughouttheentiretimewhendischargesofALPStreatedwaterareoccurring.OccupationalRadiationProtection•ReviewingwhenTEPCOreassessesALPStreatedwaterdischargefacilityonaperiodicbasiswhiletakingintoaccounttheevolutionoftheradiologicalconditions(includingoccupational114exposuredataforexternalandinternalexposuresofTEPCOworkers&contractorsincludingsub-contractors)intherelevantareasandduringnormaloperationinthefuture.5.2.IAEA’sIndependentSampling,DataCorroboration,andAnalysisTheactivitiesrelatedtothecorroborationofsourcemonitoring,thecorroborationofenvironmentalmonitoring,andthecorroborationofoccupationalradiationprotection;thesewillcontinueasdescribedinPartIVaboveandinpreviousreports.CorroborationofSourceandEnvironmentalMonitoringTheIAEAcorroborationofsourceandenvironmentalmonitoringrelatedtodischargesofALPStreatedwaterfromFDNPSiscomprisedofthreedistinctelements:•ReviewofsamplingandanalyticalmethodsforsourceandenvironmentalmonitoringrelatedtoALPStreatedwateratFDNPSusedbyTEPCOandrelevantJapaneseauthorities.•CorroborationofsourcemonitoringundertakenbyTEPCO,includingacomprehensiveradiologicalcharacterizationofALPStreatedwatersamples.•CorroborationofenvironmentalmonitoringundertakenbyTEPCOandrelevantJapaneseauthorities.OnMay2023,theIAEApublishedareport[1]detailingtheresultsofthefirstinterlaboratorycomparisonconductedforthedeterminationofradionuclidesinsamplesofALPStreatedwater.ThesefindingsprovideconfidenceinTEPCO’scapabilityforundertakingaccurateandprecisemeasurementsrelatedtothedischargeofALPStreatedwater.Furthermore,basedontheobservationsoftheIAEA,TEPCOhasdemonstratedthatithasasustainableandrobustanalyticalsysteminplacetosupporttheongoingtechnicalneedsatFDNPSduringthedischargeofALPStreatedwater.Additionalsamplingforthecorroborationofsourceandenvironmentalmonitoringwilloccurthroughouttheyearandondifferentfrequenciesdependingonoperationalconsiderations.FutureILCsareplannedforthecorroborationofsourcemonitoringin2024,andfutureILCsareplannedforthecorroborationofenvironmentalmonitoringlaterin2023afterthedischargesofALPStreatedwaterhavebegun.TheILCswillinvolvethirdpartylaboratoriesandtheIAEAiscurrentlyconsideringadditionalthird-partylaboratoriestoincludeinthesefutureILCs.CorroborationofOccupationalRadiationProtectionAnindividualmonitoringprogrammeisdesignedtoassessradiationdosestoworkersarisingfromexposureduetoexternalsourcesofradiationandfromexposureduetointakesofradionuclides.TheIAEA’scorroborationforoccupationalradiationprotectioncapabilitiesiscomprisedofthreedistinctelements:1151.CorroborationofrelevantJapaneseindividualmonitoringservices(IMS)capabilitiesformonitoringandassessingexternalexposure;2.CorroborationofrelevantJapaneseIMScapabilitiesformonitoringandassessinginternalexposure;and3.ReviewofanalyticalmethodsinexternalandinternaldosimetryusedbytherelevantJapaneseIMS.Inthefirsthalfof2023,theIAEAinitiatedthecorroborationforexternaldosimetry.TheIAEAhasissuedacontracttoasecondarystandardsdosimetrylaboratorytohavedosimetersirradiatedunderreferenceconditionsinsupportofthecorroborationofexternaldosimetry.TheirradiateddosimeterswillthenbereturnedtorelevantJapaneseIMSandtheIAEA’sRSTSLforanalysis.AftertherelevantJapaneseIMSandRSTSLhavecompletedtheiranalysisinthesecondhalfof2023,theIAEAwillcollectandanalysetheresults.TheIAEAwillcollecttheresultsfromallparticipatinglaboratoriesandconductascreeningtoensurethatalllaboratorieshavesubmittedacompleteassessmentpackagewithallnecessarydocumentation.TheIAEAwilldraftareporthighlightingtheresults,whichwillbepublishedbytheendof2023.Furthermore,inthesecondhalfof2023,theIAEAwillinitiatethestepstoconductthecorroborationforin-vitroandin-vivointernalmonitoring.TheIAEAwillidentifyvendorsfortheurinesamplesspikedwithcertifiedreferencematerialsandwillshiptheurinesamplesforin-vitroandareferencephantomforin-vivobioassaytoTEPCOaspartoftheILC.RSTSLwillalsoconductanalysesofthespikedurinesamplesandthephantomthroughout2024.5.3.RealTimeMonitoringTheIAEAhasalsochosentodisplaydataprovidedbyTEPCOonareal-timeornearreal-timebasissharethestatusoftheALPSdischargefacilitiesformembersofthepublic.ManyofthedatapointsincludedinthisrealtimemonitoringapproacharekeyoperationalparametersorcontrolsinplaceandthereforeprovidetheIAEAwithinsightsastotheongoingreliabilityoftheALPSdischargefacilities;thiswillbecombinedwiththeinsightsandobservationsgainedthroughotherTaskForceactivitiesanticipatedtooccurin2023andbeyond.ThedatafromTEPCOwillbedisplayedgraphicallyontheIAEA’swebsitealongwithashortexplanationtohelpthereaderunderstandthedifferentdatapoints.ExamplesofdatatheIAEAplanstodisplayinclude:•ALPStreatedwaterflowrates•Seawaterflowratesfordilution•Onlineradiationmonitorsinstalledinmultiplelocationsasscreeningmeasures•ConcentrationoftritiumafterdilutionAdditionally,overtime,theIAEAwilldisplaytheresultsofitsindependentcorroborationofsourceandenvironmentalmonitoring,aswellastheresultsofitscorroborationofthecapabilitiesofrelevantJapaneseindividualmonitoringservicesforoccupationalradiationprotectiononthiswebsitetoenhancetheavailabilityofrelevantdataforinterestedparties.1165.4.IAEAContinuousPresenceattheFDNPSTheIAEA,consistentwithitscommitmenttobeinginvolvedbefore,during,andaftertheALPStreatedwaterdischarges,hasacontinuouspresenceattheFDNPSfromsummer2023.TheIAEAhasadedicatedofficeattheFDNPS.Themainaspectstoconsiderinthatpresenceareto:•ObservethesafetyaspectsrelatedtotheTEPCO’sImplementationPlan•WitnessthewatersamplingactivitiesandtheprocessfordispatchingsamplestotheIAEAcorroborationandthirdpartieslaboratories.•ObservepreparatoryactivitiestakenbyTEPCOleadinguptothestartofwaterdischarges.•PeriodicallymeetwithNRAandobservetheirregulatoryinspections,theactivitiesrelatedtothedischargesofALPStreatedwaterandtheirfindings.•RoutinelyvisitthemaintechnicalequipmentandstructuresassociatedwiththeALPSwaterdischarges.•LiaisewithTEPCOifanyabnormalities,deviationsorchangesoccurduringtheimplementationandcoordinatebetweenFDNPSandIAEAHQ.•TocoordinatefutureTaskForcemeetingsattheFDNPS,asrequired.117REFERENCES1.INTERNATIONALATOMICENERGYAGENCY,IAEAReviewofSafetyRelatedAspectsofHandlingALPS-TreatedWateratTEPCO’sFukushimaDaiichiNuclearPowerStation,FirstInter-laboratoryComparisonontheDeterminationofRadionuclidesinALPSTreatedWater,IAEA,Vien-na,2023.first_interlaboratory_comparison_on_the_determination_of_radionuclides_in_alps_treat-ed_water.pdf(iaea.org)2.SecretariatoftheTeamforCountermeasuresforDecommissioning,ContaminatedWaterandTreat-edWat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19LISTOFCONTRIBUTORSCaruso,G.InternationalAtomicEnergyAgencyFreeman,E.InternationalAtomicEnergyAgencyNikolaki,M.InternationalAtomicEnergyAgencyClark,A.InternationalAtomicEnergyAgencyBrown,J.InternationalAtomicEnergyAgencyTelleria,D.InternationalAtomicEnergyAgencyOkyar,B.InternationalAtomicEnergyAgencyCruzSuarez,R.InternationalAtomicEnergyAgencyHajek,M.InternationalAtomicEnergyAgencyMelhem,S.InternationalAtomicEnergyAgencyProehl,G.InternationalAtomicEnergyAgencyAbraham-Ponti,C.InternationalAtomicEnergyAgencyBartocci,J.InternationalAtomicEnergyAgencyBlinova,O.InternationalAtomicEnergyAgencyCamin,F.InternationalAtomicEnergyAgencyCook,M.InternationalAtomicEnergyAgencyCopia,L.InternationalAtomicEnergyAgencyDeneke,M.InternationalAtomicEnergyAgencyDescroix-Comanducci,F.InternationalAtomicEnergyAgencyDioszeghy,A.InternationalAtomicEnergyAgencyFujak,M.InternationalAtomicEnergyAgencyGroening,M.InternationalAtomicEnergyAgencyHorsky,M.InternationalAtomicEnergyAgencyKim,S.-B.,InternationalAtomicEnergyAgencyLevy,I.InternationalAtomicEnergyAgencyMatsumoto,T.InternationalAtomicEnergyAgencyMcGinnity,P.InternationalAtomicEnergyAgencyMiller,J.InternationalAtomicEnergyAgencyMurphy,N.InternationalAtomicEnergyAgencyNadalut,B.InternationalAtomicEnergyAgencyOsvath,I.InternationalAtomicEnergyAgencyPatterson,S.InternationalAtomicEnergyAgencyPham,M.K.InternationalAtomicEnergyAgencyPommé,S.EuropeanCommissionJointResearchCentre,Geel,BelgiumRovan,L.InternationalAtomicEnergyAgencySeel,P.J.InternationalAtomicEnergyAgencySeslak,B.InternationalAtomicEnergyAgencySobiech-Matura,K.InternationalAtomicEnergyAgencyTucakovic,I.InternationalAtomicEnergyAgencyUlanowski,A.InternationalAtomicEnergyAgency120IndependentExternalExpertsGonzalez,A.ArgentinaTinker,R.AustraliaGregoire,M-C.CanadaLiu,S.ChinaLachaume,J-L.FranceKim,H-S.Korea,RepublicofGauvis,C.MarshalIslandsShinkarev,S.RussianFederationNettleton,J.UnitedKingdomBoyd,M.UnitedStatesofAmericaNguyenQ.H.VietNamAllindependentexpertsserveintheirindividualcapacity121ANNEX1SummaryofIAEAReviewMissionsandPublishedTechnicalReportsTheIAEAhascarriedoutfivereviewmissionstoJapansincethebeginningoftheIAEA’ssafetyreviewin2021.MembersoftheIAEATaskForceparticipatedinthesemissionsandeachmissionfocusedoninteractionswithparticularJapaneseauthoritiesorTEPCO.Aftereachofthefirstfourreviewmissions,theIAEAhaspublishedatechnicalreportthatreflectsthediscussionsbetweentheTaskForceandJapa-neseauthoritiesorTEPCO,asindicated,andwhichdocumentstheobservationsandfindingsmadebytheTaskForce.•13-19February2022:ReviewMissiontoTEPCOandMETIo29April2022:Report1published.•21-25March2022:ReviewMissiontoNRAo16June2022:Report2published.•14-18November2022:ReviewMissiontoTEPCOandMETIo5April2023:Report4ispublished.•16-20January2023:ReviewMissiontoNRAo4May2023:Report5published•29May–12June2023:ComprehensiveReviewMissionoNoreportwasissuedafterthecomprehensivereviewmission.Inaddition,theIAEAhaspublishedareportonthestatusoftheIAEA’sindependentsampling,datacor-roborationandanalysis,aswellasareportonthefirstinterlaboratorycomparisononthedeterminationofradionuclidesinALPStreatedwater.•29December2022:Report3ontheStatusofIAEA’sIndependentSampling,DataCorroboration,andAnalysisispublished.•31May2023:ReportontheFirstInterlaboratoryComparisonontheDeterminationofRadionu-clidesinALPSTreatedWaterispublished.CopiesofthesereportscanbedownloadedfromthatIAEAwebpagededicatedtotheIAEA’sALPSsafetyreview:https://www.iaea.org/topics/response/fukushima-daiichi-nuclear-accident/fukushima-daiichi-alps-treat-ed-water-discharge/reports122ANNEX2SummaryofrelevantinternationalsafetystandardsusedintheIAEAsafetyreview1.[SF-1]EUROPEANATOMICENERGYCOMMUNITY,FOODANDAGRICULTUREORGA-NIZATIONOFTHEUNITEDNATIONS,INTERNATIONALATOMICENERGYAGENCY,INTERNATIONALLABOURORGANIZATION,INTERNATIONALMARITIMEORGANI-ZATION,OECDNUCLEARENERGYAGENCY,PANAMERICANHEALTHORGANIZA-TION,UNITEDNATIONSENVIRONMENTPROGRAMME,WORLDHEALTHORGANI-ZATION,FundamentalSafetyPrinciples,IAEASafetyStandardsSeriesNo.SF-1,IAEA,Vienna(2006).2.[GSG-9]INTERNATIONALATOMICENERGYAGENCY,UNITEDNATIONSENVIRON-MENTPROGRAMME,RegulatoryControlofRadioactiveDischargestotheEnvironment,IAEASafetyStandardsSeriesNo.GSG-9,IAEA,Vienna(2018).3.[GSG-10]INTERNATIONALATOMICENERGYAGENCY,UNITEDNATIONSENVIRON-MENTPROGRAMME,ProspectiveRadiologicalEnvironmentalImpactAssessmentforFacili-tiesandActivities,IAEASafetyStandardsSeriesNo.GSG-10,IAEA,Vienna(2018).4.[GSRPart1]INTERNATIONALATOMICENERGYAGENCY,Governmental,LegalandReg-ulatoryFrameworkforSafety,IAEASafetyStandardsNo.GSRPart1(Rev.1),IAEA,Vienna(2016).5.[GSRPart2]INTERNATIONALATOMICENERGYAGENCY6.[GSRPart3]EUROPEANCOMMISSION,FOODANDAGRICULTUREORGANIZATIONOFTHEUNITEDNATIONS,INTERNATIONALATOMICENERGYAGENCY,INTERNA-TIONALLABOURORGANIZATION,OECDNUCLEARENERGYAGENCY,PANAMER-ICANHEALTHORGANIZATION,UNITEDNATIONSENVIRONMENTPROGRAMME,WORLDHEALTHORGANIZATION,RadiationProtectionandSafetyofRadiationSources:InternationalBasicSafetyStandards,IAEASafetyStandardsSeriesNo.GSRPart3,IAEA,Vi-enna(2014).7.[RS-G-1.8]INTERNATIONALATOMICENERGYAGENCY,EnvironmentalandSourceMonitoringforPurposesofRadiationProtection,IAEASafetyStandardsSeriesNo.RS-G-1.8,IAEA,Vienna20058.[GSG-7]INTERNATIONALATOMICENERGYAGENCY,INTERNATIONALLABOUROF-FICE,OccupationalRadiationProtection,IAEASafetyStandardsSeriesNo.GSG-7,IAEA,Vi-enna(2018).9.INTERNATIONALATOMICENERGYAGENCY,GenericModelsforUseinAssessingtheImpactofDischargesofRadioactiveSubstancestotheEnvironment,IAEASafetyReportSeriesNo.19,IAEA,Vienna(2001).10.[GSG-8]INTERNATIONALATOMICENERGYAGENCY,UNITEDNATIONSENVIRON-MENTPROGRAMME,RadiationProtectionofthePublicandtheEnvironment,IAEASafetyStandardsSeriesNo.GSG-8,IAEA,Vienna(2018).11.[IAEASafetyGlossary]INTERNATIONALATOMICENERGYAGENCY,IAEANuclearSafetyandSecurityGlossary,2022InterimEdition,IAEA,Vienna,(2022).123ANNEX3ListofupdatesandamendmentstoTEPCO’sImplementationPlanandNRARegulatoryReviewMilestones1.ListofupdatesandamendmentstoTEPCO’sImplementationPlan,includingtheREIA•November2021ohttps://www.tepco.co.jp/en/hd/newsroom/press/archives/2021/20211117_01.html•December2021ohttps://www.tepco.co.jp/en/hd/newsroom/press/archives/2021/20211221_02.html•April2022ohttps://www.tepco.co.jp/en/hd/newsroom/press/archives/2022/20220428_03.html•May2022ohttps://www.tepco.co.jp/en/hd/newsroom/press/archives/2022/20220513_01.html•July2022ohttps://www.tepco.co.jp/en/hd/newsroom/press/archives/2022/20220715_01.html•November2022ohttps://www.tepco.co.jp/en/hd/newsroom/press/archives/2022/20221114_01.html•February2023o(14th)https://www.tepco.co.jp/en/hd/newsroom/press/archives/2023/20230214_01.htmlo(20th)https://www.tepco.co.jp/en/hd/newsroom/press/archives/2023/20230220_01.html•April2023ohttps://www.tepco.co.jp/en/hd/newsroom/press/archives/2023/20230424_02.html2.NRARegulatoryReviewMilestones•24December2021oPublicreviewmeetingbetweenNRAandTEPCO•11December2021oPublicreviewmeetingbetweenNRAandTEPCO•20December2021oPublicreviewmeetingbetweenNRAandTEPCO•27December2021oPublicreviewmeetingbetweenNRAandTEPCO•1January2022oPublicreviewmeetingbetweenNRAandTEPCO•7January2022oPublicreviewmeetingbetweenNRAandTEPCO•15January2022oPublicreviewmeetingbetweenNRAandTEPCO•25January2022oPublicreviewmeetingbetweenNRAandTEPCO•1February2022oPublicreviewmeetingbetweenNRAandTEPCO•10February2022oPublicreviewmeetingbetweenNRAandTEPCO•18February2022oPublicreviewmeetingbetweenNRAandTEPCO•11March2022oPublicreviewmeetingbetweenNRAandTEPCO•15April2022oPublicreviewmeetingbetweenNRAandTEPCO124•19May–17June2022oNRAestablishesapubliccommentperiodforfirstregulatoryreviewresults•22July2022oFirstregulatoryreviewresultsapprovedbyNRACommission•21November2022oPublicreviewmeetingbetweenNRAandTEPCO•7December2022oPublicreviewmeetingbetweenNRAandTEPCO•21December2022oPublicreviewmeetingbetweenNRAandTEPCO•27December2022oPublicreviewmeetingbetweenNRAandTEPCO•17February2023oPublicreviewmeetingbetweenNRAandTEPCO•23February–24March2023oNRAestablishesapubliccommentperiodforsecondregulatoryreviewresults•10May2023oSecondregulatoryreviewresultsapprovedbyNRACommission125ANNEX4#JapanlegalandregulatoryprovisionsappliedtotheFDNPS1.ActontheRegulationofNuclearSourceMaterial,NuclearFuelMaterialsReactors“ReactorRegu-lationAct”Thedocumentisrelatedtotherequirementsforlicensingofnuclearfacilitiesinordertopreventaccidentre-sultingfromi)nuclearfuelmaterial,ii)materialcontaminatedbynuclearfuelmaterial,iii)reactors,andiv)toprotectspecifiednuclearfuelmaterial,andv)ifnecessary,todesignatefacilitiesthatrequirespecialmeasuresfortheoperationalsafetyorphysicalprotectionofthespecifiednuclearfuel.Thefollowingtopicsareexplicitlyincluded:•Therequirementforthepreparationofanimplementationplanfornuclearfacilitiesincludingmeasuresoperationalsafetyorphysicalprotectionofthespecifiednuclearfuel.•Ifafacilityisnolongerclassifiedasanuclearfacility,theobligationtosubmitanimplementationplanexpires.•Ithastobeannouncedofficiallyi)ifafacilityisclassifiedanuclearfacilityorii)revokedtheclassifica-tionasnuclearfacility.•Alicenseeofthenuclearfacilityshallcreateanimplementationplantogetthepermissionforoperation.•Themodificationofanapprovedimplementationplanrequirestheapprovaloftheregulatorybody.•Ifdeemednecessarybytheregulatorybody,theregulatorybodymayrequestanamendmentoftheim-plementationplan.•Anylicenseeofthenuclearfacilityshallimplementmeasuresforoperationalsafetyandphysicalprotec-tionofnuclearfuelmaterialincompliancewiththeimplementationplan.•Thelicenseeofanuclearfacilityshallundergoaninspectionconductedbytheregulatorybodyforcheckcompliancewiththeimplementationplan.2.CabinetorderonspecialprovisionsoftheActontheRegulationofNuclearSourceMaterialNuclearFuelandReactorsabouttheNuclearReactorsatTEPCO’sFukushimaDaiichiNuclearReactorsThedocumentssummarizestheapplicationofspecificparagraphsofthe“ActontheRegulationofNuclearSourceMaterialNuclearFuelandReactors”toincludealsotheworksfordecommissioningoftheFukushimaDaiichiNuclearPowerStation.3.NRAOrdinanceforOperationalSafetyandProtectionofSpecifiedNuclearFuelMaterialsoftheNu-clearReactorsatTEPCO’sFukushimaDaiichiNPSOrdinanceoftheNuclearRegulationAuthorityNo.2onApril,12,2013Thedocumentdealswithaspectsonoperationalsafetyandthesafehandlingoffuelmaterials.Ithas42articles,thearticles6-8,11,21,23,30,32,34-41havenocontent.Article16isthemostimportantarticleregardingthedischargeofALPStreatedwater.Itincludesthepossiblemeasurestoreduceradionuclideconcentrationsbeforethedischarge(e.g.:filtering,evaporation,adsorptionbytheion-exchangeresins,storage,dilutionwithlargevolumesofwater).TheradionuclideconcentrationsshallcomplywiththeconcentrationlimitspecifiedbytheNuclearRegulationAuthority.5.NotificationtoEstablishRequirementsforOperationalSafetyandPhysicalProtectionofSpecifiedNuclearFuelMaterialsoftheNuclearReactorsatTEPCO’sFukushimaDaiichiNPS126NotificationNo.3oftheNuclearRegulatoryAuthorityonApril12,2013Thedocumentdealswithrequirementsforoperationalsafetyandthesafehandlingoffuelmaterials.Ithas13articles,thearticles11and12havenocontent.Thedocumentprovidesregulatorycriteriafor:•Surfacedensitylimits•DoseLimitsforRadiationWorkers•DoseLimitsforRadiationWorkersduringEmergencyWork•ConcentrationLimitsRadionuclidesinAiratWorkplaces•ConcentrationLimitsforRadionuclidestobedischargedtotheatmosphereandtowaterbodies.•GeneralguidanceoncalculationofdosesforWorkers•LimitsofradioactivityconcentrationsthatdonotrequireencapsulationincontainersArticle1RecordofDoseEquivalentRate,etcArticle2DesignationofanuclearfacilityArticle3StandardstobeEndeavouredtoObserveintheCaseofStoragebyElectromagneticMethodsArticle4SurfaceDensityLimitArticle5DoseLimitsforRadiationWorkersArticle6ConcentrationLimitforRadiationWorkersArticle7DoseLimitforRadiationWorkersPertainingtoEmergencyWorkArticle8ConcentrationLimitOutsidetheSurroundingMonitoringArea,etcArticle9CalculationofDose,etc.PertainingtoExternalRadiationArticle10CriteriaPertainingtoPersonResponsibleforOperationArticle13LimitofRadioactivityConcentrationofSubstancesContaminatedbyNuclearFuelMaterialsNotRequiredtoBeEncapsulatedinContainersArticle13-2ApplicationFormforApprovalofMeasuresConcerningTransportofSubstancesSignificantlyDifficulttobeEncapsulatedinContainersArticle13-3DoseEquivalentRateforLoadandTransportEquipmentArticle13-4HazardousMaterialsArticle13-5SignArticle13-6ApplicationFormforApprovalofSpecialMeasuresArticle13-7DoseEquivalentRatePertainingtoLoadSubjecttoSpecialMeasuresArticle13-8CalculationofDoseEquivalentRatePertainingtoTransportofNuclearFuelMaterial,etc.atFactoryorPlaceofActivityArticle14AuthorityofOfficialsWhoConductInspections6.NotificationtoEstablishDoseLimitsinAccordancewiththeProvisionsoftheNRAOrdinanceonActivitiesofRefiningNuclearSourceorNuclearFuelMaterials,etc.NotificationNo.8oftheNuclearRegulatoryAuthorityonAugust31,2015Thisdocumentisreferredinthe“NotificationtoEstablishRequirementsforOperationalSafetyandPhysi-calProtectionofSpecifiedNuclearFuelMaterialsoftheNuclearReactorsatTEPCO’sFukushimaDaiichiNPS”(NotificationNo.3oftheNuclearRegulatoryAuthorityonApril12,2013).DoselimitsThedocumentdefinesadoselimitsforthepublicforeffectivedoseof1mSv/a;ifapprovedbytheNuclearRegulationAuthority,theeffectivedoselimitmaybe5mSv/a.Limitsfortheequivalentdoseforskinandlensoftheeyeare50mSv/aand15mSv/arespectively.127Theselimitsareappliedinthefollowingrulesandregulations:•RulesforSmelting•RulesforTestReactor•RulesforNuclearRawMaterialUse•RulesforNuclearFuelMaterialUse•RulesforProcessing•RulesforReprocessing•RulesforCommercialReactor•RulesforResearchandDevelopmentReactor•RulesforCategory1RadioactiveWasteDisposal•RulesforCategory2RadioactiveWasteDisposal•RulesforRadioactiveWasteManagement•RulesforStorage•RulesforStorageContract•RegulationsonTechnicalStandardsforDesignandConstructionMethodsofProcessingFacility•RegulationsonTechnicalStandardsforDesignandConstructionMethodsforSpecifiedWasteDisposalFacilityorSpecifiedManagementFacility•RegulationsonTechnicalStandardsforPerformanceofProcessingFacility•RegulationsonTechnicalStandardsforPerformanceofReprocessingFacility•RegulationsonTechnicalStandardsforCommercialPowerReactorsandtheirAffiliatedFacilities•RegulationsonTechnicalStandardsforPerformanceofSpecifiedWasteDisposalFacilityorSpecifiedManagementFacility•RegulationsonTechnicalStandardsforDesignandConstructionMethodsofSpentFuelStorageFacility•RegulationsonTechnicalStandardsforPerformanceofSpentFuelStorageFacility•RegulationsonTechnicalStandardsforNuclearPowerReactorunderResearchandDevelopmentStageanditsAffiliatedFacilitiesLimitsforaverageradionuclideconcentrationsThedocumentprovidesforallradioisotopesrelevantforexposureonworkplacesandfordischargesofradionuclidestotheenvironmentthefollowingquantities:1.Dosecoefficientsforeffectivedoseforinhalation[mSv/Bq]2.Dosecoefficientsforeffectivedoseforingestion[mSv/Bq]3.Limitsforradionuclideconcentrationinairatworkingplaces[Bq/cm³]4.Limitforradionuclideconcentrationsinairtobedischargedfromnuclearfacilitiestotheatmo-sphere[Bq/cm³]5.Limitforradionuclideconcentrationsinwatertobedischargedfromnuclearfacilitiestowaterbodies[Bq/cm³]Formanyisotopes,thevaluesaregivenforvariouschemicalforms.Guidanceisprovidedhowtoevaluatecompliancewithlimits.Thesevaluesformaximalradionuclideconcentrationsareusedinthefollowingrulesandregulations:6.RulesforTestReactor7.RulesforNuclearFuelMaterialUse8.RulesforProcessing9.RulesforNuclearRawMaterialUse10.RulesforCommercialReactor11.RulesforCategory1RadioactiveWasteDisposal12.RulesforCategory2RadioactiveWasteDisposal12813.RulesforRadioactiveWasteManagement14.RulesforStorage15.RegulationsonTechnicalStandardsforDesignandConstructionMethodsofReactors,etc.usedforResearchReactor16.RegulationsonTechnicalStandardsforPerformanceofReactors,etc.UsedforResearch17.RegulationsonTechnicalStandardsforDesignandConstructionMethodsofProcessingFacility18.RegulationsonTechnicalStandardsforPerformanceofReprocessingFacility19.RegulationsonTechnicalStandardsforCommercialPowerReactorsandTheirAffiliatedFacili-ties20.RegulationsonTechnicalStandardsforDesignandConstructionMethodsforSpecifiedWasteDisposalFacilityorSpecifiedManagementFacility,21.RegulationsonTechnicalStandardsforPerformanceofSpecifiedWasteDisposalFacilityorSpecifiedManagementFacility22.RegulationsonTechnicalStandardsforDesignandConstructionMethodsofSpentFuelStorageFacility23.RegulationsonTechnicalStandardsforPerformanceofSpentFuelStorageFacility,24.RulesforResearchandDevelopmentReactor25.RegulationsonTechnicalStandardsforNuclearPowerReactorunderResearchandDevelopmentStageandItsAffiliatedFacilities6.ItemsrequiredforMeasureswhichshouldbetakenatTokyoElectricPowerCo.,Inc.’sFukushi-maDaiichiNuclearPowerStationinlinewiththeDesignationastheSpecifiedNuclearFacilityDecisionofNRACommission,7November2012ThedocumentsummarizestheworkareastobeconsideredduringdecommissioningofthedamagedFDNPP.Thefollowingaspectsshouldbetakenintoaccountandthefollowingmeasuresshouldbetakenduringthedecommissioningwork:•MeasurestobeTakenwithregardtotheOverallProcessandRiskAssessment•ItemsconcerningMeasurestobetakenforDesignandEquipment—Monitoringofreactors—Removalofresidualheat—Monitoringofprimarycontainmentatmosphere—Maintenanceofaninertatmosphere—Fuelremovaland,appropriatestorageandmanagementofremovedfuel—Ensuringpowersource—Designconsiderationsforlossofpower—Treatment,storage,andmanagementofradioactivesolidwaste—Treatment,storage,andmanagementofradioactiveliquidwaste—Radiationprotection,etc.intheareasurroundingthesitebyrestrictingreleaseofradioactivematerials,etc.—Management,etc.ofworkers’exposuredose—Emergencymeasures—Designconsiderations•Measuresforsecurityofthespecifiednuclearfacility•Measuresforphysicalprotectionofspecifiednuclearfuelmaterials•Measuresforretrievaloffueldebrisandreactordecommissioning•Considerationsfordevelopingtheimplementationplan•Effortstofacilitatetheunderstandingoftheimplementationplan•Reviewprocedurefortheimplementationplan129ANNEX5TritiumintheenvironmentTritiumisaradioactivehydrogenisotopewithoneprotonandtwoneurons,itistheheaviestisotopeofhydrogen.Thephysicalhalf-lifeoftritiumis12.3years.Tritiumisalow-energy-beta-emitter,themeanbeta-energyisonly5.7keV.Tritiumisproducedbynaturalandartificialprocesses.Naturally,tritiumisgeneratedmainlyintheupperlayersoftheatmosphereasaresultofreactionsofcosmicradiationwithnitrogenandoxygen.Tritiumisproducedinnuclearfacilities,especiallyinnuclearpowerplantsandreprocessingplants.Fortheperiod1998to2002,inUNSCEAR[1],theaverageannualreleaseoftritiumfromnuclearfacilitieswasestimatedtobe12PBqand16PBqtotheat-mosphereandtheaquaticenvironment,respectively.Fromnuclearinstallations,tritiumisreleasedpredominantlyastritiatedwater(HTO)orelementalhydrogen,whichreactsquicklywithoxygentoformHTO,whichthenenterstheglobalhydrologicalcycle.Furthermore,anthropogenictritiumwasgeneratedduringatmospherictestofnuclearweapons.AccordingtoUN-SCEAR[2],during504atmospherictestsconductedintheperiodfrom1945to1980,about200000PBqoftritiumwerereleased.Approximately,95%ofalltritiumreleasesfromatmospherictestsoccurredintheperiodfrom1952to1962.DataontritiumconcentrationsinoceanswerecompiledandanalysedbyOmsetal.[3].Fromthesedata,averagetri-tiumconcentrationsfortheupper500moftheoceanswereestimatedfor21compartmentsoftheAtlanticOcean,In-dianOcean,andPacificOcean.Becauseatmosphericnuclearweaponstestswereconductedprimarilyinthenorthernhemisphere,thevaluesarehighernorthoftheequatorthansouthoftheequator.Thetritiumconcentrations—decaycorrectedforJanuary1,2016—areintherangeof0.006-0.12Bq/L.Standarddeviationsfortritiumconcentrationsvaryforthedifferentoceaniccompartments,witharangeofabout15-90%ofthemean.IntheNorthPacific,tritiumconcentrationsarereportedintherangeof0.027-0.057Bq/L,andameantritiumconcentrationof0.057±0.015Bq/Lisreportedfortheareabetweenlatitudes30Nto45N.Inmarinewaters,mosttritiumisboundinthewaterasHTO.However,becausetritiumatomsareinterchangeablewithnormalhydrogenatoms,someofthetritiumingestedbymarineorganismscanbeincorporatedintoorganiccompoundssuchascarbohydrates,fats,proteins,andotherorganiccompounds;thistritiumfractionisreferredtoasorganicallyboundtritium(OBT)[1].AtritiumatominOBTthatisboundtoacarbonatomisessentiallyfixeduntilthecompoundismetabolized(i.e.,thetritiumisnotexchangeable).Tritiumboundtooxygen,sulphur,nitrogen,orphosphorusatomsisconsideredreadilyexchangeablewithhydrogeninwater,sotritiuminsuchbindingsisnotconsideredasOBT.Inthehumanbody,theturnoveroftritiumboundtoHTOismuchfasterthanthatofOBTtritium.Thisisalsore-flectedinthedosecoefficientsforHTOandOBT1.IntheICRPmodel[4]forestimatingdosecoefficientsforuptakeoftritium,itisassumedthat97%ofHTOtakenupintothebloodisdistributedinbodywaterand3%ofHTOisconvertedtoOBT.Thebiologicalhalf-lifeoftritiuminhumansis10and40daysforHTOandOBT,respectively.ThedosecoefficientsforingestionforallagegroupsconsideredinICRPareaboutafactorof3higherforOBTcomparedtoHTO[4].1The‘dosecoefficient’isthecommittedeffectivedosefromanintakeofaradionuclide(ingestionorinhalation)foraunitintakeofradioactivity.TheunitisSv/Bq.Dosecoefficientsaregivenfordifferentagegroupsin[4]134INTERNATIONALATOMICENERGYAGENCYVIENNA
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