Implementationof International Safety Standards
for Radioactive Waste Management
into Japanese Regulations

Toshiso KOSAKOThe University of Tokyo,
Graduate School of Engineering,
Nuclear Professional School
1Conceptual Figure ofLow Level Radioactive Waste Disposal Facility

2Conceptual Figure of Step-Wise Control of LLW DisposalRadioactivity

1st Stage
25-30 yFrom A

2ndStage
25-30yFrom B

3rd Stage
300y
from BStage
Of nocontrol

TimeStart ofConstruction
AClosureB

End ofControl
3

Radiation Safety Standardfor Radioactive Waste
Disposal ？
It’s clear！
Why？

10μSv/y is a constitution！
Based on the decision of Radiation Council !

Other Countries：
USA 0.25mSv/y, France 0.25mSv/y, Germany 0.3mSv/yRadiation Council:
Recommendation to every Ministries on the Technical Issue
Related to Radiation Protection

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Radiation Council： General Administrative Group（Dec. 1987）
On Regulation Exclusion Dose to the Near Surface Disposal for
Solid Radioactive Waste
Dose limit to the individuals and Regulation Exclusion Dose tothe Japanese Near Surface Disposal(1) Dose limit to the individuals(2) ICRP’s view on the individual dose to the regulation
exclusion(3) Regulation exclusion dose to the Japanese near surface
disposal
Negligible low dose of radiation control: 10μSv/y(4) Remarks on the regulation exclusion doseBase：ICRP Pub.46 （July, 1985）: “ Radiation Protection
Principles for the Disposal of Solid Radioactive Waste”
5Base：ICRP Publ.46 （July, 1985)“Radiation Protection Principles for the Disposal of Solid
Radioactive Waste”
Points：3 Principles of Radiation Protection(Justification, Optimization, Dose limitation)
Rad. Waste Disposal, Long-term, Potential
Exposure, Risk Concept
Large Volume Waste > Concept of Exemption,
10μSv/y ( Optimization of Protection)
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Nuclear Safety Commission① Basic concept on safety judgment of radioactive waste repository(March, 1988, Rev. 1993, 2001)｢1988 Safety Judgment Guideline｣② Common important issue on safety regulation of Rad. Waste Disposal(June, 2004)③Basic concept on safety regulation of low level rad. waste repository(Intermediate report)(July, 2007)④ Near surface disposal of RI and laboratories waste
Basic concept on safety regulation of near surface disposal of solidradioactive waste from RI facilities(January, 2004)
Basic concept on safety regulation of near surface disposal of solidradioactive waste from research facilities(April, 2006)“ The guideline of radiation dose for post closure is the level of nocontrol from the view point of radiation control .”7Types of Radioactive Waste Disposal Facility0m

低Low
Near
Surface (Trench)
浅地中トレンチ処分

浅地中ピット処分
NEAR Surface (Pit)

10m

50m

100m

放射能レベルIntermediate Depth
余裕深度処分

300m

Geological
地層処分
High
高8

Categorization and Regulations of Radioactive Waste Disposal(NSC, AEC, MEXT, NISA etc.)
AEC

NSCRegulations

HLW

LLW

Clearance
9Radiation Protection Policy of Radioactive
Waste Disposal by ICRP
• Related ICRP Publications-Radiological Protection Policy for the Disposal ofRadioactive Waste（Publ.77, 1998）
Protection Policy for RW as a Whole-Radiation Protection Principles for the Disposal of Solid
Radioactive Waste（Publ.46, 1985）
Principle for Exemption, Solid Waste-Radiation Protection Recommendations as Applied to the
Disposal of Long-Lived Solid Radioactive Waste（Publ.81, 1999）
10Principle for Long-Lived Radioactive Waste Disposal

ICRP’s Principle of Radiation Protection✓3 Principles for Radiation Protection(Justification, Optimization, Dose Limit)✓Protection for PublicDose Limit：1mSv/y
Optimization（ALARA, Dose Constraint）
0.3ｍSv/yIntervention（Human Intrusion, around 10mSv）✓Adjustment to other guides
Exhaust, Draining Guides
Site Release standard IAEA-WS-G.5.1（0.3mSv/y: Unconditional Release) 11

Standard for Site Release
IAEA ： WS-G5.1------------------------------------------- 1mSv/yPublic Dose Limit

Possible: Conditional Site Release-------------------------------------------- 300Sv/ｙ

Doe Constraints

Possible: Unconditional Site Release12Policy of Radioactive Waste
Disposal：Dose Constraints• Control of Public Exposure：
Optimization of Protection using Dose Constraint→Prospective Use for Future Planning• Max. of Constraint ：1mSv/ｙModerate Value：about 0.3mSv/ｙ• Environmental Model, Metabolism Modelfor Dose Estimation
Seek for Representative & Realistic Model
Avoid to abuse Materials
13Choices of Risk Estimation Measures by ICRP Publ. 81

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Optimization under Long Term Situation：Natural Process１）Natural Process-Seismic Property, Retention capability,
Canister Design >> possible to reduce theprobability and the amount of exposure-Dose Constraint of 0.3mSv/yRisk Constraint of 10-5 order-Aggregated Approach
Dose/Probability Approach←more information
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Optimization under Long Term Situation：Human Intrusion
Human Intrusion-Inevitable under “Concentrate and retain” policy-Presence of natural resources, Institutional control
measures, Selection of repository depth>> Reduce the probability and/or magnitude of exposures-To use dose and risk constraint is not appropriate-Existing annual dose around 10mSv/y:generic reference level below which intervention is not
likely to be justifiable- Existing annual dose around 100mSv/y:generic reference level above which intervention should16be consideredSafety Standards by IAEA
Safety Requirement on Radioactive Waste Disposal
Safety Series No. 111-F “Principle of Radioactive Waste Management”○ Safety Standards Series No. WS-R-1 “Near Surface Disposal ofRadioactive Waste” （1999）
・do not exceed an appropriate fraction of Dose limit(1 mSv/y),or its risk equivalent.
・no more than about 0.3 mSv/y(Dose constraint by ICRP)
would be appropriate○ Safety Standards Series No. WS-R-4 “Geological Disposal ofRadioactive Waste” （2006）
・Dose limit of the Public is 1mSv/y for all practices.
・Do not exceed a dose constraint of not more than 0.3 mSv/yor of the order of 10－5/y risk constraint○ Unification of WS-R-1 and WS-R-4 (2009)
DS354 “Disposal of Radioactive Waste”
・Dose Constraint
below 0.3mSv／yor Risk Constraint 10－5／y order・Unintended Human Intrusion at the Stage of post Closure
below 20mSv／y17

Conclusion at Radiation
Council/General Administrative Group
Radiation Protection Standards for RadioactiveWaste Disposal☆ For Natural Process:
Dose Constraint below 0.3mSv/yor Risk Constraint of 10－5/y order☆ Post-Closure Stage:
Unintended Human Intrusion
below 20mSv/y18

Point Issue No.1
Q１．Change from 10μSv/y to 300μSv/y isa Relax of Restrictions. Dangerous？
A1: Base Line is 1mSv/y of Dose Limit forPublic. As a Dose Constraint, we have
300μSv/y.
Q2. Is it reasonable in comparison with 1mSv/y of
Natural Radiation (External)?
And, comparison with other environmental risk?
A2. The Reason of Dose Limit to the Public
1mSv/y19

Point Issue No.2
Q3．”Dose of No Control” is 10μSv/y.
So, it is wrong of 300μSv/y use!
A3. 10μSv/y is used in Exemption and Clearance.
The key word of controllability is important.
Property of Repository：number, over lap,barrier（artificial, natural）
Q4. Is it tolerable for the safety discussion on
Long-Term Uncertainty？
A4. Dose/Probability Approach, Aggregated Approach,
optimization of protection, Special case (Long-term)
・Isolation, Marker, Moderate institutional control

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Point Issue No.3
Q5． Harmonization to Other Protection Standards?
A5: ＋Site Release Dose Standard（Land, Building）
Application of Constraint（300μSv/y）＋Discharge as one of Rad. Waste Disposals（Exhaust, Draining）＋Consolidated Approach to Radioactive WasteDisposal Safety Standard System
Clearance etc. Graded Approach＋Natural Occurring Radioactive Material（NORM)＋Rad. Protection to the Public,Protection of the Environment
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What we need to do？
• Systematic Risk Expression on the Radiation Protection
Standard for Radioactive Waste Disposal• No need of always decrease of standards.
Rational, Scientific Change
Emergency： 100mSv ＞＞About 500mSv
Weight of Heredity： 0.5>0.25>0.20>0.08• Graded Risk Level (Big, Medium, Small)for Radiation Risk
• The Goal of Safety is NOT ZERO !
“As Low”＝”ZERO Goal”＝” No Use of Nuclear and Radiation”
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