JapaneseRegulationsforWasteManagement

NorikazuYAMADA

RegulatoryStandardandResearchDivision,SecretariatofNRA,NuclearRegulationAuthority,Japan

ICRP Workshop on Surface Disposal of Radioactive WasteNovember 6 2017, Fukushima, Japan

公開決裁完了まで機密性2

Category of radioactive waste disposal

ü Generic maximum radioactive concentrations are listed above for each type of repositories.

ü Specific radioactive concentrations should be decided so as to comply with the dose criteria, considering the site characteristics and the repository design.

ü Average concentrations of wastes are well below the generic maximum concentrations.

300m

100m

HLW

Trench disposal

Concrete vault disposal

Intermediate Depth Disposal

The burial of category 1 waste

ＴＲＵ wasteThe burial of category 2 waste

Geological disposal

Co-60 10 GBq/tSr-90 10 MBq/tCs-137 100 MBq/t

C-14 100 GBq/tCo-60 1 PBq/tNi-63 10 TBq/tSr-90 10 GBq/tCs-137 100 TBq/tα emitters 10 GBq/t

C-14 10 PBq/tCl-36 10 TBq/tTc-99 100 TBq/tI-129 1 TBq/tα emitters 100 GBq/t

Generic maximum concentrations for each waste package

2

3

SeaLandsurface

Disposal tunnel

Access Ramp

Connectingtunnel

Surfacefacility

Main tunnel

Cross section

approx.18m

approx.18m

approx.13m

approx.12m

approx.14mSupport

Backfill(soil,concrete)Bentonite

Mortar fillWaste packages

Reinforced concrete pitMortar

Concept of Intermediate Depth Disposal

Waste package

Waste

Main body of waste package

Additionalshield

Lid（welded)

Longitudinal section

*1: Figures are cited from the Federationof Electric Power Companies of Japan

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Regulatory procedures on LLW disposal

Operational activities

• Application of License

Pre-construction

activitiesConstruction activities

Closure

Stepwise control (about 300～400 y)

Post closure activities (Institutional control)

• Application of Decommissioning plan

Start of Operation

Safety Inspection(monitoring, PSR)

Safety Confirmation of Disposal Facility

Safety Confirmation of Radioactive Waste Package

Termination of license

Restriction of Land use (for Intermediate Depth Disposal)

After termination of license

4Construction and operation Post closure Passive safety

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

1.E+08

1.E+09

1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08

Relativeeffect

(nuclidecon

centration

(Bq/t)/CLlevel(Bq

/t))

YearRelative effects of wastes vs. time

HLW

ILW*1)

Rel

ativ

e ef

fect

s *2

)

(equ

ival

ent

to m

Sv/y

)

LLW

TerminationoflicenseRequiredisolationperiodfrombiosphere

Characteristics of Radioactive Wasteof Intermediate Level Disposal

*1)AveragevaluesforradioactivewastefromoperationanddecommissioningofBWR,PWR,andGCR*2)1mSv/ywhensumofnuclideconcentrationdividedbyclearancelevelequalsto100

ü Requirements for design and controls are related to the characteristics of wastes.ü Wastes containing longer half lives of radionuclides require longer time of control or

isolation. 5

河川等

Drinking river water, ingestion of agricultural products, ingestion of fish

Agricultural work

Radio Nuclides Pathway of Intermediate Depth Disposal

Drinking well water

6

Engineering barrier

WasteNatural barrier

Requirements for radioactive waste disposal

7

Category ID Requirements

Radiationprotection R1R2

DuringLicenseAfterlicensetermination

DesignNaturalprocess

A Locationofrepository

B Limitationonconcentrationsoflong-livednuclides

C Confinementofnuclidesuntilthetermination oflicense

D1D2

Containmentofnuclides• Engineeredbarriers• Naturalbarrier

Humanintrusion

E PreventionofhumanintrusionF Mitigationofconsequenceof humanintrusion

Control

G ConfirmationofbarrierfunctionH PeriodicsafetyreviewI Closureoftunnel

J Monitoring

K Confirmationofdecommissioning

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• Avoid direct hit by volcanic eruption during at least 100ka• Avoid direct hit by faulting during at least 100ka• Maintain minimum depth of 70m taking into account of uplift and

erosion at least 100ka • Away from significant known mineral resources

Requirements on Location of Repository(Exclusion Criteria)

Consider uplift and erosion in 100ka

ALARA (Optimizationofradiationprotection)TheprincipleofOptimizationisdefinedasthesourcerelatedprocesstokeeplikelihoodofincurringexposures(wherethesearenotcertaintobereceived),thenumberofpeopleexposed,andthemagnitudeofindividualdosesaslowasreasonablyachievable,takingeconomicandsocietalfactorsintoaccount.(ICRPPubl.103)

• Optimizationisaframeofmind,alwaysquestioningwhetherbesthasbeendoneintheprevailingcircumstances.

• Compareandselectpreferablemeasurefromavailableoptions.• Optimizationisaniterativeprocesstakingintoaccountboth

technicalandsocio-economicdevelopment.• Requirementnotforthesolutionbutfortheprocess.• Thegoalofaoptimizationofprotectionisnotamathematically

optimizedsolution.

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Radiation Protection Criteria for Waste Disposal (1/2)

BackgroundandspecificfeatureofALARAforradioactivewastedisposal

• Protectionaftertheterminationoflicensereliesonthecharacteristicsoftheselectedsiteandthedesignofthedisposalfacility.

• Estimateddoseandriskinthefarfuturearenottheabsolutemeasuretoensuresafety.

• Sitecharacteristics,elementofBestAvailableTechnique(BAT),conceptofgoodpractice,reliableengineering,etc.areimportant.

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Radiation Protection Criteria for Waste Disposal (2/2)

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Requirements on Disposal Design

START

END

Design Process① Design concept

③ Selection of location of disposal

② Engineering barrier design

④ Selection of disposal system

⑤ Dose assessment of public

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Barrier function Barrier Performance Related FeatureConfinementand Containment of Nuclide

ConfinementDuration of opening holes on waste package

Corrosion rate

Retardation Long travel time ofnuclide in barriers Kd value, solubility

Low ReleaseRate

Low release rate from engineered barrier

Diffusivity, width and numbers of cracks

Stable Condition

Restrictground water inflow

Low ground water inflow to engineered barrier

Permeability

Stabilize Mechanical Condition

Small deformation Young’s modulus, compression strength

Stabilize Geochemical Condition

Buffer of red-ox andchemical condition

Corrosion condition of metal, degradation condition of cement and clay material

Example of engineered barrier function

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Barrier Function Barrier Performance Related FeatureContainment

Retardation

Long travel time of ground water.Long travel time of nuclide.

Kd value, ground water velocity, distance from highly conductive geological feature.

StableCondition

StabilizeGeochemicalCondition

Stagnant ground water flow.Buffer of red-ox andchemical condition

Buffer capacity of minerals.Distribution of geological formation.Distribution of geochemical condition.

Example of Natural Barrier Function

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• NRAispreparingnewregulatoryframeworkfortheIntermediateDepthDisposal.- Disposalshouldbedesignedsoastoconfinenuclideswithintheengineeredbarrier,untiltheterminationofthelicense.- Disposalshouldbeisolatedfromnaturaldisruptiveeventsandhumanactivitiesforaperiodofatleast100Kyears.- DisposalshouldbedesignedandnaturalbarriershouldbeselectedsothatthereleaseofnuclidesfromthedisposalwouldbeAsLowAsReasonablyAchievable.Thedosefortherepresentativepersonshouldn’texceeddoseconstrain.- Inventoryoflong-livednuclidesshouldbelimitedbelowthelevelconsideringthedoseofpersonhypotheticallycontactingwithwastesat100Kyearsafterclosureshouldnotexceed20mSv/y.

• NRAisconsideringthewaytotaketheseregulationframeworktothatofshallowlanddisposal,eventhoughtheywouldn’thavemuchdesignoptionsandmostofradioactivitieswilldecaybythetimeofterminationoflicence.

Conclusion

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Thank you for your attention.