IAEAInternational Atomic Energy Agency

Roger Seitz

Addressing Future Human Actions for

Safety Assessment

Summary from CSM on Human Action

And Intrusion in Disposal Facilities

IAEA

Overview

• Background• General Approach• Representative Categories• Site- and Repository-Specific Factors

• Regional Practices• Timing and Countermeasures

• Decision-making

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Position paper – Summary

Summary of the Position Paper

• General recommendations based on international publications and experiences in MSs

• Considerations and initial suggestions on the development of stylised representations of future human action

• Suggestions for a methodology to develop stylised inadvertent human intrusion scenarios and implementation for specific disposal site

• Identification of topics for a future working group

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Background - Perspective

Radioactive waste management is conducted in a manner that considers factors not addressed in other industries in respect of potential impacts on future generations

Consideration of future human actions after loss of institutional controls (not considered for hazardous waste)

Consideration of very long time frames

“Concentrate and Contain” philosophy Need to maintain perspective regarding the overall benefits of this approach relative to the potentially greater hazards that could result from intrusion

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Background - Expectations

IAEA, ICRP and OECD/NEA• Protect inadvertent intruder, not advertent

intruder• Limited stylized scenarios, current habits• Intrusion considered in the context of

intervention and optimization

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Potential Concept for Methodology

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General identification of Human actions

Analysis of human actions considering Site conditions (Societal, hydro-Geological, climate, geography …)

Analysis of human actions considering Repository design (Including natural and engineered barriers, safety functions,

time-frames …)

Preliminary « qualitative » Screening of scenarios (Simple calculations, intermediate indicators …)

Representative human actions categories (Drillings, excavation works …)

List of « site specific inadvertent human intrusion scenarios » (Simple quantitative description, depth and diameter, location …)

Reduced list of scenarios (Recommandations for performance assessment)

(

Performance assessment process

Input from the general performance assessment

process (« Covering scenarios »,

biosphere data …)

Chapter 3

Chapter 4

Not developped in this paper

Set of possible human actions (Assumptions made regarding rationale and technical means)

New iterarion within the safety case developpment

Conclusions possibly giving steering indications on the siting, on the design and on the WACs

IAEA

Potential Concept for Methodology

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General identification of Human actions

Analysis of human actions considering Site conditions (Societal, hydro-Geological, climate, geography …)

Analysis of human actions considering Repository design (Including natural and engineered barriers, safety functions,

time-frames …)

Preliminary « qualitative » Screening of scenarios (Simple calculations, intermediate indicators …)

Representative human actions categories (Drillings, excavation works …)

List of « site specific inadvertent human intrusion scenarios » (Simple quantitative description, depth and diameter, location …)

Reduced list of scenarios (Recommandations for performance assessment)

(

Performance assessment process

Input from the general performance assessment

process (« Covering scenarios »,

biosphere data …)

Chapter 3

Chapter 4

Not developped in this paper

Set of possible human actions (Assumptions made regarding rationale and technical means)

New iterarion within the safety case developpment

Conclusions possibly giving steering indications on the siting, on the design and on the WACs

IAEA

Representative Categories of Intrusion

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Drilling and Excavation/Construction

Considerations for those categories

Direct exposure and/or exposure through groundwater ??

Based on current technologies and human habits

Scenarios should be

o illustrative indicators of safety

x predictions of safety based on what is expected to occur

Not intended to obtain “yes or no” conclusion, rather to bring

additional information for improvements to siting, design or WAC

IAEA

Site and Facility Considerations

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Site Considerations

Natural resources

Groundwater quantity and composition

Soil, rock properties

Land use (role of passive controls)

Design considerations

Effectiveness of barriers (waste, container, facility, site) against

intrusion (delay or preclude)

Effect of intrusion (penetration, cuttings, water contamination, etc.)

Source term depletion

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Draft Report from WASSC Subgroup

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Draft prepared but never published

Addressed many of the topics

discussed in March meeting

Systematic approach, Stylized

scenarios, Countermeasures

Identified issues related to intrusion

Time scales, Intrusion as a separate

event, Probabilities, Inhomogeneities,

Overcautiousness

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Decision-Making

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Not “yes or no”, inform siting, design and WAC

(optimisation)

Caution to not create a situation where overly cautious

intrusion scenario could cast doubt on a very good

site/design

Maintain perspective relative to expectations in other

industries

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Perspective on Cautious Assumptions

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Assume loss of control (unique to RW disposal??)

Assume intrusion will occur (unique to RW disposal??)

Assume intrusion occurs immediately following loss of active control?

Assume occurs within footprint of facility rather than outside footprint?

Assume direct contact with waste (or probability of hitting waste)?

Assume contact with higher activity waste (or average)?

Assume barrier is compromised (or assume delay before intrusion)?

Assume drill will not deflect around barrier, container or waste form?

Assume driller/construction worker will not recognize that something is wrong?

Assume resident establishes home/garden in cuttings?

Assume all cuttings are respirable?

Assume cuttings will behave like soil for uptake in plants?

Extreme exposure assumptions rather than similar to typical remediation

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Practical Considerations

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Identify areas where consensus can be reached

Expected to be difficult to obtain consensus on details

regarding scenarios because of existing precedents

Focus on efforts that will contribute to a safety report

Capture considerations related to countries working to

implement new disposal capability

Geologic and near surface

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…Thank you for your attention

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Potential Discussion Topics

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Geologic or Near-Surface

Effectiveness of Institutional Controls (land use)

Effectiveness of Barriers (timing)

Use of Stylized Scenarios

Probabilities of Intrusion

Inhomogeneities

Overcautiousness

Interpretation of results (“yes or no”, design support, etc.)

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Potential Working Groups from March

Topical areas for a future WG• WG1: Technical Conditions

– to address specifics on possible human actions based on site conditions (e.g. type of drilling, well diameter and depth, etc.)

• WG2: Societal Aspects – to address societal context of future human action scenarios (e.g. considerations on the level of development of a country, etc.)

• WG3: Linking Technical and Societal Conditions with Design – to consider the synthesis of site and societal considerations with the actual repository design to develop the full scenarios to be considered (e.g. considerations on timing of the intrusion activity)

• WG4: Practical application of results from analyses considering future human actions – to consider how scenarios regarding future human actions are used in the process of siting, designing and developing WAC – Regulatory and public perception considerations

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Additional Ideas

• Divide by geologic and near-surface disposal• Combine technical and societal aspects• Update draft IAEA document into Safety Report

• Considerations:• Limit number of groups• Focus on areas where consensus can be reached• Practical expectations, achievable goals• Want to have product(s) that will contribute to a safety report at the

end of the project

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