Addressing Future Human Actions for
Safety Assessment
Summary from CSM on Human Action
And Intrusion in Disposal Facilities
Roger Seitz
IAEA
International Atomic Energy Agency
Overview
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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
Chapter 3
General identification of Human actions
Representative human actions categories
(Drillings, excavation works …)
Chapter 4
Analysis of human actions considering Site conditions
(Societal, hydro-Geological, climate, geography …)
Set of possible human actions (Assumptions made
regarding rationale and technical means)
Analysis of human actions considering Repository design
(Including natural and engineered barriers, safety functions,
time-frames …)
List of « site specific inadvertent human intrusion scenarios »
(Simple quantitative description, depth and diameter, location …)
Input from the general
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performance assessment
Preliminary « qualitative » Screening of scenarios
(Simple calculations, intermediate indicators …)
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(Including natural and engineered barriers, safety functions,
time-frames …)
Potential Concept for Methodology
List of « site specific inadvertent human intrusion scenarios »
(Simple quantitative description, depth and diameter, location …)
Input from the general
performance assessment
process
(« Covering scenarios »,
biosphere data …)
Preliminary « qualitative » Screening of scenarios
(Simple calculations, intermediate indicators …)
Reduced list of scenarios
(Recommandations for performance assessment)
(
Not developped
in this paper
Performance assessment process
Conclusions possibly giving steering indications
on the siting, on the design and on the WACs
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New iterarion within the
safety case developpment
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Representative Categories of Intrusion
 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
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Site and Facility Considerations
 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
 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
 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
 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
 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
 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.)
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WG2: Societal Aspects
– to address societal context of future human action scenarios
(e.g. considerations on the level of development of a country, etc.)
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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)
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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:
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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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