Definition, Role and Documentation
of the Safety Case: Quick Review
Workshop on the Application of the
IAEA Methodology and Safety
Assessment Framework (SAFRAN)
Tool for the Safety Case and Safety
Assessment for Predisposal
Management of Disused Sealed
Radioactive Sources (DSRS)
Athens, Greece, 23-27 June 2014
Earl Fordham
Washington Department of Health, USA
([email protected])
IAEA
Outline of the Presentation
• Overview of Safety Case
• Specific issues
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Evolution of the safety case;
Graded approach;
Defense in depth;
Reliability;
Expected lifetime of the facility;
Long term storage;
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Overview: Purpose of safety case
• Demonstrate that all planned activities can be
carried out in a safe manner
 The SC concept will be of particular importance for
large predisposal waste management facilities such as
national centres for the processing and storage of
radioactive waste.
• Provide guidance for the design, engineering
and planning of operations to ensure safety
• Input to regulatory process, including
evidence of compliance and arguments for
confidence building
IAEA
International Course on Management of Waste, Clausthal-Zellerfeld, Germany, 6-15 October 2010
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Objectives and Roles of SC and SA (GSG-3)
 Integrating scientific and other information
 Demonstrating safety (incl. uncertainties)
 Demonstrating compatibilities with next
waste management steps (e.g. disposal)
 Aiding decision making on the
authorisation/ licensing of the facilities
 Other information and arguments that
support continued development, use or
eventual decommissioning of the facility
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Overview: What is a Safety Case?
 The collection of arguments and evidence, including
the outcome of safety assessment, in support of the
safety of a facility or activity (GSR-5, GSG-3)
 The basis for the safety considerations in respect of
siting and locating facilities, construction, operation
and decommissioning of the facility, including the
justification for changes
 The basis for interaction and dialogue between the
operating organization and the regulatory body
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Overview: What’s in the Safety Case?
• Normally includes the findings of a safety
assessment, together with:
• Consideration of the confidence level in these
findings,
• A written statement assessing the adequacy of the
assessment work for the decisions to be taken, and
• The need for any further work to reduce uncertainty.
• Components of the Safety Case can be found
in GSG-3
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Role of the Safety Case in
Ensuring Long Term Safety
• Interdependencies:
• Transfer of Ownership, Responsibilities, Information
• Long Term Strategies for management of DS, RW and SF
• Safety implications of delayed disposal
• Informing decision making (e.g., management of legacy
sites, considering new/expanded nuclear programmes)
Waste and materials
• Demonstration of Safety
Pretreatment
• Licensing and authorization
• Interactions w Stakeholders
Radioactive material
Exempt waste
Treatment
(for reuse/recycle)
and materials
• Engineering Barriers
• Management Systems
STORAGE
Conditioning
TRANSPORT
• Monitoring and Inspections
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Disposal
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Development and content of SC and SA
 Some countries do not use the term SC in a formal
way, but the approaches and processes to
demonstrate safety similar
 The operator shall prepare a safety case and a
supporting safety assessment. Do we have any
regulator/operators here today?
 In the event of a step by step site development or in
the event of the modification of the facility or activity,
the SC and its supporting SA shall be reviewed and
updated as necessary. Any one going beyond storage?
 Regulatory body is responsible to derive and
document in a clear and unambiguous manner the
criteria on which the regulatory decision making
process is based
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• SPECIFIC ISSUES (step 6):
- Evolution of the safety case
- Graded approach
- Defense in depth
- Reliability
- Expected lifetime of the facility
- Long term storage
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Introduction
During facility lifecycle, the safety
case will evolve in five main stages:
• Concept and siting;
• Design;
• Construction and commissioning;
• Operation and modifications;
• Shutdown and decommissioning.
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Concept and siting (cont.)
The output of the safety case at this stage of
development is justification that the facility
(or activity) is safe to be built.
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Design
• During the design development and construction, the safety
case will be further developed to provide a mature
assessment of the engineering and the impact of the
facility or activity;
• The safety case should demonstrate that:
 Likelihood of a component of the system failing is low,
 In the event of degradation, the loss of a safety function
of one component does not jeopardize the safety of the
whole system (defense in depth)
• Can be safely constructed and operated.
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Construction and commissioning (cont.)
• The safety case at this stage should demonstrate
that the as constructed facility meets the safety
requirements specified in the final design.
• This should include the impact of any modifications
to the design, which have been implemented
during the construction stage.
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Operation
• Must investigate and recertify any significant
differences between the actual and predicted
performance of the facility discovered during
commissioning testing.
• To recertify facility, perform PSR periodically,
when plant status or management changes,
or after regulatory changes.
• SC should document procedural changes for
safety, record tracking systems, and sufficient
expertise exists for operations and other
interdependencies, as needed.
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Operation (cont.)
The aim of the operational
safety case is to justify that
the facility can be operated
safely for a specific period
and can then be safely
decommissioned.
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• SPECIFIC ISSUES:
- Evolution of the safety case
- Graded approach
- Defense in depth
- Reliability
- Expected lifetime of the facility
- Long term storage
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Graded approach
• The scope/level of detail of the safety assessment for
a particular facility shall be consistent with the
magnitude of the possible radiation risks from the
facility (e.g., simple site; simple assessment),
• Expect greater efforts will be needed in developing SC
& SA for a large treatment facility than for a small lowlevel waste storage facility.
• Learn the degree of detail required for a SA by first
undertaking relatively simple SA’s that provide an
indication of the potential levels of risk.
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Graded approach: Criteria (cont.)
• Various criteria may be used in determining the level of
understanding that should be expected for a particular facility;
• Criteria may include:
 Safety significance (most important),
 Complexity,
 Maturity of plant operators/operations.
• Facility performance viewed in terms of:
 Releases from normal operation,
 Potential consequences of anticipated operational
occurrences and reasonably foreseeable accidents,
 Potential significance of low probability events with
potentially high consequences.
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• SPECIFIC ISSUES:
- Evolution of the safety case
- Graded approach
- Defense in depth
- Reliability
- Expected lifetime of the facility
- Long term storage
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Defense in depth: Concept
• The defense in depth concept is centered on several levels of
protection including successive barriers and other safety
functions preventing the release of radioactive material to the
environment and minimizing exposures;
• The concept includes:
 Maintaining the effectiveness of the barriers by averting
damage to the facility and to the barriers themselves;
 Further measures to protect the public and the environment
in case of unexpected malfunction or degradation of barriers
(up to & including infrequent design basis events).
• Example: combine passive engineered barriers (preferred) with
approved procedures.
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Scope of the safety case for predisposal RW
• Relevant facilities / activities:
 Processing of radioactive waste
 Clearance and Discharges
 Storage facilities
 Transport
 Intervention situations (e.g. old storage facilities)
• All types of wastes
 low level to high level waste
 disused sealed sources
 NORM
IAEA
International Course on Management of Waste, Clausthal-Zellerfeld, Germany, 6-15 October 2010
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Suggested SC Documentation Format
• No universal, but suggested format (Section 7):
• Executive Summary,
• Introduction & Context (e.g., why) for SC,
• Strategy for Safety (selection, location, barriers),
• Safety Assessment, and
• Synthesis and Conclusions.
• Minimum Safety Case is just the SA with
operating limits and conditions.
• Actual format is subject to your audience.
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Safety Case contents
The safety case (SC) shall:
 Include a description of how all the safety aspects of the
site, the design, operation, shutdown and
decommissioning of the facility, and the managerial
controls satisfy the regulatory requirements,
 Demonstrate the level of protection provided and shall
provide assurance to the regulatory body that safety
requirements will be met,
 Include arguments justifying the approaches taken in the
safety case on the basis of information that is traceable,
and
 Document the arguments at a level of detail and to a
quality sufficient to demonstrate safety.
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Safety Case contents con‘t
 Discussion of the various waste types and the rationale for the
chosen/proposed waste management options,
 Areas and the processes used at the site,
 Managerial structure and regulatory controls over the facilities,
 Plans regarding the development, operation and shutdown and
decommissioning of the facilities,
 Safety assessment (SA),
 Other information and arguments supporting the development
and use of a facility.
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Any questions?
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