Module SCD 4: Safety Case
Segment SCD 4.3
Documentation and use of the safety case
Learning Objectives
The objectives of this segment are to consider:
• How to compile and draw together all the different
information comprising the safety case.
• How to use the safety case.
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Introduction
 In the previous presentations we studied the role of the
safety case, the development of the safety case and
components of the safety case and the Specific issues
important for the development of the safety case.
 The safety case is the basis for the safety considerations in
respect of siting and locating facilities, construction,
operation, decommissioning or closure 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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Learning Objectives
The objectives of this segment are to consider:
• How to compile and draw together the all of the
different information comprising the safety case.
• How to use the safety case.
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Documentation of the safety case
• The safety case provides a basis for decision making and is
presented to the relevant decision makers for their review and
consideration.
• The confidence of the interested parties in the findings of the
safety case should, however, be enhanced if the arguments and
evidence are presented in a manner that is open and
transparent, and all relevant results are fully disclosed and
subject to quality control and independent review.
• The structure and the documentation process are influenced by
the expectations of the intended audience.
• The documentation of the safety case should cover, at a
minimum, the safety assessment and the operating limits and
conditions.
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Documentation of the safety case
The main elements should be clearly documented
and presented, and should include:
• the executive summary;
• the introduction and context for the safety case (or safety
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assessment);
the strategy for safety;
the safety assessment;
synthesis and conclusions;
a plan for follow-up programmes and actions;
traceability and transparency of the documentation;
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Documentation of the safety case
The main elements should be clearly documented
and presented, and should include:
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•
•
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the executive summary;
the introduction and context for the safety case;
the strategy for safety;
the safety assessment;
synthesis and conclusions;
a plan for follow-up programmes and actions;
traceability and transparency of the documentation;
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Executive summary
• At the highest level, the documentation of the
safety case should contain an executive
summary that briefly describes:
– the project,
– the main safety related issues associated
with the project,
– the evidence, arguments and main
assessment results,
– the proposed follow-up and options for
mitigation that would address the safety
issues identified, and
– any uncertainties and concerns of interested
parties.
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Executive summary
• For most interested parties, the summary will provide the first
and most lasting impression of the project. Consequently, this
section should be clear, complete and concise.
• The use of summary tables, graphics and flow charts should be
considered as these are effective ways to present information
clearly and accurately.
• The use of complicated technical terminology should be avoided,
to the extent possible.
• The executive summary can be presented under a separate
cover and may be more widely distributed than the rest of the
documentation. It may also be presented in different languages
to meet the needs of local communities.
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Documentation of the safety case
The main elements should be clearly documented
and presented, and should include:
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•
•
•
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•
the executive summary;
the introduction and context for the safety case;
the strategy for safety;
the safety assessment;
synthesis and conclusions;
a plan for follow-up programmes and actions;
traceability and transparency of the documentation;
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Introduction and context for the safety case
In the introduction, the following main aspects should be
outlined:
• A brief description of the project that provides its specific
objectives, background, various stages involved and its
current status;
• The policy and regulatory contexts under which the safety
case has been prepared and presented;
• The roles and responsibilities of the various organizations
involved in the decision making process, including the
framework for public consultation and involvement;
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Introduction and context for the safety case
In the introduction, the following main aspects should be
outlined:
• A clear guide to the decision making process;
• A comparison with other similar projects (national and
international);
• A discussion of the status and maturity of development of
the technologies that will be used;
• A statement on the need for and importance of the project,
in order to support and justify the safety case;
• A discussion of alternatives that have been considered and
reasons for the preferred alternative;
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Introduction and context for the safety case
In the introduction, the following main aspects should be
outlined:
• The key decisions that have been and will have to be made
during the course of the proposed project;
• A description of critical timing considerations associated
with the project;
• An overview of how compliance with regulatory
requirements will be ensured by the operator and how
compliance will be verified by the regulatory body;
• An overview of the operator’s management system and its
ability to address the challenges associated with the project
adequately.
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Documentation of the safety case
The main elements should be clearly documented
and presented, and should include:
•
•
•
•
•
•
•
the executive summary;
the introduction and context for the safety case;
the strategy for safety;
the safety assessment;
synthesis and conclusions;
a plan for follow-up programmes and actions;
traceability and transparency of the documentation;
14
Strategy for safety
• Following the presentation of the purpose and context for
the safety case, the documentation of the safety case
should provide an overview of the high level approach that
will be used to achieve safety.
• The objective of the section on strategy for safety is to
demonstrate that the overall approach and methods
adopted to design, assess, construct, operate, shut down
and decommission the waste management facility or
activity are adequate to ensure safety.
• The section should also include confidence building
arguments that are relevant to the strategy for safety.
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Strategy for safety
The main aspects to be considered include the following:
• Strategy and approach to manage the different stages of
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development of the facility or activity (e.g. site evaluation,
construction, operation, shutdown, decommissioning);
How the adopted strategies apply good engineering principles
and practices;
Management and reduction of uncertainties;
The basis for making decisions;
Safety features embedded in the design of the facility and the
levels of defence in depth used;
Safety Strategy
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Strategy for safety
The main aspects to be considered include the following:
• The rationale for selecting the assessment methodology and
the time frame and time windows for the assessment,
including a discussion of the various assessment approaches
and the tools used to verify, confirm and compare
assessment findings;
• Peer reviews conducted and consistency with international
guidance and practices;
• Other high level arguments as appropriate.
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Documentation of the safety case
The main elements should be clearly documented
and presented, and should include:
•
•
•
•
•
•
•
the executive summary;
the introduction and context for the safety case;
the strategy for safety;
the safety assessment;
synthesis and conclusions;
a plan for follow-up programmes and actions;
traceability and transparency of the documentation;
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Safety assessment
• The section on safety assessment should document the
details of the safety assessment, which forms the scientific
and technical basis for the safety case procedure.
• This is the section that will be scrutinized by technical
reviewers and the regulatory body.
• Documenting the safety assessment involves a detailed
description of the context for the safety assessment, each
step of the assessment, the assessment findings and the
conclusions.
• Confidence building arguments should be documented at
each step of the safety assessment as well as for the
overall safety assessment.
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Safety assessment
• All relevant data, assumptions, models and the results of
the assessment should be fully documented.
• The level of confidence in the evaluation results or safety
margin and future actions should be identified.
• The quantitative and qualitative outcomes of the safety
assessment form the basis for the safety case.
• These should be supplemented by supporting evidence for
and reasoning about the robustness and reliability of the
safety assessment and its assumptions, including
information on the performance of individual system
components as appropriate.
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Documentation of the safety case
The main elements should be clearly documented
and presented, and should include:
•
•
•
•
•
•
•
the executive summary;
the introduction and context for the safety case;
the strategy for safety;
the safety assessment;
synthesis and conclusions;
a plan for follow-up programmes and actions;
traceability and transparency of the documentation;
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Synthesis and conclusions
This section on synthesis and conclusions should:
• Draw together the key findings from the safety assessment;
• Highlight the main evidence, analysis and arguments that
quantify and support the claim that the facility or activity is safe;
• Present an evaluation of uncertainties and unresolved issues
and discuss planned steps to resolve them;
• Describe complementary evidence for safety, e.g. evidence for
safety beyond the time frame for which quantitative assessment
has been performed;
• Present statements of confidence that take account of additional
evidence and arguments that complement the findings of the
safety assessment.
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Documentation of the safety case
The main elements should be clearly documented
and presented, and should include:
•
•
•
•
•
•
•
the executive summary;
the introduction and context for the safety case;
the strategy for safety;
the safety assessment;
synthesis and conclusions;
a plan for follow-up programmes and actions;
traceability and transparency of the documentation;
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Follow-up programmes and actions
• In particular when the safety case is developed in a step by
step approach, it is important to put each revision of the
safety case into the context of the overall development
process.
• Necessary activities for the subsequent stage of
development of the safety case should be described, such
as acquisition of additional data or planned improvement in
modelling.
• If certain activities can only proceed after decision points or
milestones have been reached (e.g. decisions on the site of
the facility or activity), these should be identified.
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Documentation of the safety case
The main elements should be clearly documented
and presented, and should include:
•
•
•
•
•
•
•
the executive summary;
the introduction and context for the safety case;
the strategy for safety;
the safety assessment;
synthesis and conclusions;
a plan for follow-up programmes and actions;
traceability and transparency of the documentation;
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Traceability and transparency of the documentation
• All documents produced in the context of the
safety case, should convey a consistent
message about safety issues. In other words,
the message should remain the same and not
be changed to suit the expectations of a
particular audience.
• The main documentation of the safety case
should provide sufficient information for the key
safety arguments and the evidence supporting
them to be clearly understandable.
• The documentation should show that the safety
case is based on sound scientific evidence and
arguments using established technical
experience and analyses.
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Traceability and transparency of the documentation
• The documentation should be clearly written and
uncertainties and limitations as well as their implications for
safety should be acknowledged.
• The documentation should be well structured, transparent
and traceable.
• The documentation should be transparent such that the
information is readily available to interested parties, by
being clear and understandable and by clearly presenting
the justification and rationale behind key assumptions.
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Traceability and transparency of the documentation
• The documentation should be such that the procedures followed and
the key decisions taken in the development of the facility or activity and
of the safety case are traceable.
• This should include showing how follow-up actions and programmes
are put forward at early stages to confirm assumptions made or how
unresolved uncertainties have been addressed and/or will continue to
be addressed.
• It should also be shown how key decisions have been documented and
recorded by including a clear referencing system.
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Traceability and transparency of the documentation
• The safety assessment methodology should be well
structured, transparent and traceable.
• It should enable the regulatory body and other technical
reviewers to follow the logic and understand the
assumptions used in the assessment easily and, where
desired, to reproduce the assessment results.
• The safety case should provide a full description of the
practical methods used to identify and reduce uncertainties
• The documentation should identify the assumptions and
uncertainties that impact the most on safety.
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Traceability and transparency of the documentation
• The documentation of the safety case should be updated
periodically in accordance with a systematic plan.
• The operator should implement proper controls over the
process for approval of the documentation of the safety
case and over updates to the set of data and parameter
values, models, scenarios and computer codes on which
the safety case is based and that are used in safety
assessment.
• Documents should be subject to formal review processes.
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Traceability and transparency of the documentation
• Traceability necessitates a clear and complete record
of the decisions and assumptions made, and of the
models, parameters and data used in arriving at the
results.
• The record should include information on when and
by whom various decisions and assumptions were
made, how these decisions and assumptions were
implemented, what versions of modelling tools were
used, and what the ultimate sources of the data are,
etc.
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Traceability and transparency of the documentation
• Traceability necessitates the highest standards of quality
assurance.
• Traceability necessitates a clear and complete record of the
decisions and assumptions made, and of the models,
parameters and data used in arriving at the results.
• Traceability further implies that the regulatory body or other
technical reviewers should be able to reproduce part or all
of the assessment results from the documentation of the
safety assessment.
• Traceability will be greatly increased by presenting the
safety case in a hierarchically structured set of documents.
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Learning Objectives
At the end of this segment the learner will be able to know:
• How to compile and draw together the all of the different
information comprising the safety case.
• How to use the safety case.
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Uses of the safety case
• The safety case may be used for several purposes
depending on the stage of the design, construction,
operation, shutdown and decommissioning of the facility or
activity.
• At an early stage, safety assessments should be used to
compare and assess the feasibility of different options.
• Later, the safety case should be used to inform the
licensing process and to provide for the establishment of
suitable limits and conditions on operation.
• The safety case should, at all times, be consistent with the
current stage in the lifetime of the facility.
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Uses of the safety case
The uses of the Safety Case compromises among
others:
• Comparison of options
• Prioritization of data acquisition and research and
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development
Facility design and operation
Licensing
Construction and commissioning
Operation
Monitoring
Management controls
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Comparison of options
The safety case may be used to provide a basis for the
comparison of disposal options, for example:
• Comparison between different sites for new facilities and
prioritization of site characterization, and related research
and development;
• Comparison of different types, designs for the facility;
• Comparison of different risk management and remediation
options for existing facilities;
• Comparison of different pretreatment options.
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Uses of the safety case
The uses of the Safety Case compromises among
others:
• Comparison of options
• Prioritization of data acquisition and research and
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development
Facility design and operation
Licensing
Construction and commissioning
Operation
Monitoring
Management controls
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Prioritization of data acquisition and research
and development
• The safety case should integrate existing knowledge on a
wide range of topics and should provide a means of judging
their relative importance.
• Initially, the safety case may be based largely on generic
data but, as the programme to develop the facility
progresses, the safety case will include more site specific
information.
• The safety case should be used to guide and prioritize the
acquisition of data and research and development
programmes so that they address important areas of
uncertainty as identified in the safety case.
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Uses of the safety case
The uses of the Safety Case compromises among
others:
• Comparison of options
• Prioritization of data acquisition and research and
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development
Facility design and operation
Licensing
Construction and commissioning
Operation
Monitoring
Management controls
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Facility design and operation
• The safety case should be used to assist in the design and
operation of the facility throughout its development.
• The construction and operation of the facility should, at all
times, be consistent with the safety case, so that
operational decisions do not cause unintentional effects on
performance of the system.
• Operational decisions relevant to safety should be
investigated and may require an update of the safety case
prior to their implementation.
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Uses of the safety case
The uses of the Safety Case compromises among
others:
• Comparison of options
• Prioritization of data acquisition and research and
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development
Facility design and operation
Licensing
Construction and commissioning
Operation
Monitoring
Management controls
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Licensing
• A principal function of the safety case is in the licence
application and approval process.
• The regulatory body may require that the safety case be
revised at various stages in the licensing process, including
for approval to construct, operate and shut down the facility,
and whenever there are significant changes in the facility or
activity.
• The safety case should anyway be updated periodically to
reflect new information acquired.
License
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Licensing
• The licence for predisposal waste management facilities
and activities located at other facilities, such as nuclear
power plants, may be granted within the framework of the
licensing procedure for the main facility.
License
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Uses of the safety case
The uses of the Safety Case compromises among
others:
• Comparison of options
• Prioritization of data acquisition and research and
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development
Facility design and operation
Licensing
Construction and commissioning
Operation
Monitoring
Management controls
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Construction and commissioning
• In conducting the safety assessment, a
number of assumptions will be made in
relation to the design, construction,
commissioning, operation and
decommissioning of the facility.
• It is important that these assumptions are
realized in practice.
• The plant should be built according to the
assessed design, and the structures,
systems and components that are important
to safety should undergo commissioning
tests to demonstrate that they perform as
expected.
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Uses of the safety case
The uses of the Safety Case compromises among
others:
• Comparison of options
• Prioritization of data acquisition and research and
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development
Facility design and operation
Licensing
Construction and commissioning
Operation
Monitoring
Management controls
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Operation
• The operating procedures for the facility should be drawn
up to ensure that the facility will be operated in accordance
with design specifications.
• Such procedures should be assessed for adequacy as part
of the overall safety assessment and safety case process.
• A formal procedure for control of modifications should be
established and maintained that will ensure that any
proposed changes to the facility or its proposed operations
remain within the assessed envelope.
• Additional assessment should be carried out to
demonstrate the acceptability of a modification.
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Uses of the safety case
The uses of the Safety Case compromises among
others:
• Comparison of options
• Prioritization of data acquisition and research and
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development
Facility design and operation
Licensing
Construction and commissioning
Operation
Monitoring
Management controls
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Monitoring
• The safety case should be used when
evaluating potential exposure
pathways and in establishing and
reviewing the environmental
monitoring programme for the site and
the surrounding area.
• Surveillance environmental monitoring
programmes should be established to
verify that the facility or activity is
performing as expected and that each
component is achieving its safety
function.
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Uses of the safety case
The uses of the Safety Case compromises among
others:
• Comparison of options
• Prioritization of data acquisition and research and
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•
development
Facility design and operation
Licensing
Construction and commissioning
Operation
Monitoring
Management controls
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Management controls
The safety case should demonstrate the necessary combination
of management controls, covering, for example:
• quality assurance,
• maintenance,
• surveillance testing,
• staff education and training,
• emergency preparedness,
• radiation protection,
• record keeping and industrial safety
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Overall Summary
This segment covered:
• How to compile and draw together all of the different information
comprising the safety case. Which are the main components of the safety
case
• How to use the safety case in different applications such as:
• Comparison of options
• Prioritization of data acquisition and research and development
• Facility design and operation
• Licensing
• Construction and commissioning
• Operation
• Monitoring
• Management controls
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