International Atomic Energy Agency
Group 3
Moderator: Jack
Rapporteur: Joerg
Subjects to tackle
• Uncertainty and uncertainty management
• Make a link, place a hook towards
uncertainty (management)
• Understanding of the safety envelope.
• Clarification of difference between design
target and safety envelope. Involvement of
regulator in both aspects? Regulatory
requirements and safety envelope
• Verbalize concept of agreement between
operator and regulator
International Atomic Energy Agency
Subjects to tackle
• Term “initial state”  clarify, confusion
on evolution of initial state - discuss.
• ‘Initial conditions’
• Closure activities included to define initial
state
• Get rid of “assumed initial state”
• Uncertainty on initial state due to transients
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International Atomic Energy Agency
International Atomic Energy Agency
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Helpful
• PRISM
Outcomes of Task Group 4:
Managing Uncertainties
conducted by Roger Seitz
were included into the PRISM report (chapter 9).
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International Atomic Energy Agency
Task 4: Managing Uncertainties
Summary
Roger Seitz
05 December 2012
Rough Graphic for Types of Uncertainty
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Conclusions
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The need to address the performance of natural and engineered
systems and policy/governmental status over long time-scales
inevitably leads to complex uncertainties that pose challenges to
decision-makers.
Awareness is the first step towards managing uncertainties.
Five general classes of uncertainties were identified:
data/parameter, model, future/scenario, resources and contextual.
The first three categories are site specific, quantifiable to differing
degrees, and can be considered within a safety assessment.
These uncertainties have to be considered in the design
target/safety envelope.
The last two are difficult to quantify and are more relevant at the
Member State level and need to be considered when developing
waste management policies and as part of project planning.
These uncertainties can cause modifications/changes during the
operation period.
International Atomic Energy Agency
Options
Confidence Building
• Use of Management Systems (LOOP)
• Involvement of Interested parties
• Discussion of Options
• Passive Safety (Safety Envelope)
• Defence in Depth
• Robustness (Safety Envelope)
• Scientific and Technical / Engineering
Principles (Design Target)
• Understanding the Disposal System
• Monitoring (Design Target)
• Independent Peer Review
• Completeness of the Safety Case
(update due to loop result)
• Traceability and Transparency
• Complementary Safety Indicators
• Multiple Lines of Reasoning
• Plans for Addressing Significant
Unresolved Issues (Plan and
implementation as relevant to Design
Target/ Safety Envelope)
• Use of International Standards
Managing Uncertainties
• Sensitivity Analysis
• Uncertainty Analysis
• Quality assurance/Quality control
• Communication of confidence building
• Site Characterization
• Expert judgment/elicitation
• Verification/Validation of Models
• Plume matching/assimilation
• Decision analysis (multi criteria and multi
attribute, cost benefit)
• Waste acceptance criteria
• Laboratory experiments
• Reality check – simple calculation
• Demonstration analogues
• Alternative conceptual models
• Data estimation – inverse methods
• Alternative designs
• Balancing realism and conservativism
• Monitoring and surveillance
• Use of different types of models
(probabilistic/deterministic)
• Safety Functions and FEPs
• Concept of reasonable assurance
• Documentation of assumptions (regulatory
and resources)
International Atomic Energy Agency
Subjects to tackle
• Term “initial state”  clarify, confusion
on evolution of initial state - discuss.
• ‘Initial conditions’
• Closure activities included to define initial
state
• Get rid of “assumed initial state”
• Uncertainty on initial state due to transients
International Atomic Energy Agency
International Atomic Energy Agency
International Atomic Energy Agency
International Atomic Energy Agency
International Atomic Energy Agency
Not Helpful Necessary Modifications
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Title
Instead of preclosure safety please use operational safety
Page 1, Capter 1.1.1
It is not only the nuclear industry, which produces waste (MIR)
Thousands of years may be the wrong order for long term safety
Page 2, Chapter 1.1.3
civil engineering works is not the challenge but mining activities
Page 5 and 6
Handshake is misleading, propose to remove this term
Example on page 6/7
number of possible defective packages undetected should be
included into the Design Target
This example is not a good one.
Example on page 6
instead of “determines” influences or is an indicator
delete “sorption”
General: Terminology should be checked!!!
International Atomic Energy Agency
International Atomic Energy Agency