overview of iaea's projects on safety goals and … of iaea's projects on safety goals and...
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International Atomic Energy Agency
Overview of IAEA's Projects on Safety Goals and
Integrated Risk Informed Decision Making
Presented by: Irina Kuzmina, PhD, Safety Officer
Safety Assessment Section/ Division of Nuclear Installation Safety/
Department of Nuclear Safety
1st Consultants’ Meeting on the INPRO Collaborative Project:
Review of Innovative Reactor Concepts for Prevention of Severe Accidents and Mitigation of
their Consequences (RISC)
31 March – 2 April 2014, IAEA, Vienna, Austria
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HIGHLIGHTS
■ Safety Goals
● Background, status, high-level overview of the
contents
■ Integrated Risk Informed Decision Making
(IRIDM)
● Background, status, high-level overview of the
contents
� IAEA-TECDOC publication series
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WHAT DO WE MEANT BY SAFETY GOALS?
� Safety Goals for nuclear installations: characteristics aimed to assist in answering the fundamental question: “How safe is safe enough?”
� Generally, Safety Goals provide a measure of sufficiency/adequacy of safety provisionsembedded in the design of a nuclear installation and its operational process
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Safety Margins
CHARACTERIZATION OF SAFETY GOALS
SAFETY
GOALS
Defense-in-Depth• Multiple barriers and
levels of protection
• Diversity and
redundancy within and
between safety
systems
• Single failure criterion
• Postulated initiating
events, etc.
QUALITATIVE
0.0E+00
1.0E-05
2.0E-05
3.0E-05
4.0E-05
5.0E-05
6.0E-05
7.0E-05
8.0E-05
9.0E-05
1.0E-04
QUANTITATIVE
Limits for
respective
RISK METRICS -
frequencies of
undesirable
consequences
(events/time unit)
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SAFETY FUNDAMENTALS (1/2)
The Fundamental Safety Objectiveis
to protect people and the environment from harmful
effects of ionizing radiation
� ‘Safety’ means the protection of people and the environment against radiation risks
�Ten safety principles have been formulated, on the basis of which safety requirements are developed and safety measures are to be implemented in order to achieve the fundamental safety objective
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SAFETY FUNDAMENTALS (2/2)
Principle 6: Limitation of risks to individuals
“Measures for controlling radiation risks must ensure that no individual bears an unacceptable risk of harm”
1) Risk associated with nuclear installations needs to be assessed
2) Guidance (criteria) for ‘unacceptable risk’ need to be established
3) Relevant measures (design features and procedures) provided
Implications:
SAFETY GOALS
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INSAG-12
Basic Safety Principles for Nuclear Power
Plants, 75-INSAG-3 Rev.1, INSAG-12, A
report by the International Nuclear Safety
Advisory Group, IAEA, Vienna, 1999
� Revision of the original 75-INSAG-3
(1988)
� Qualitative safety concepts,
Defense-in-Depth emphasized
� Current reference IAEA publication
for probabilistic safety goals
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ILLUSTRATION OF THE CONCEPT OF NUMERICAL SAFETY GOALS
CONSIDERED IN INSAG-12 & NS-G-1.2*
*Comment: NS-G-1.2 is superseded by SSG-2, where the consideration is not
included
0.0E+00
1.0E-05
2.0E-05
3.0E-05
4.0E-05
5.0E-05
6.0E-05
7.0E-05
8.0E-05
9.0E-05
1.0E-04CDF for
operating NPPs
CDF for new NPPs
0.0E+00
1.0E-06
2.0E-06
3.0E-06
4.0E-06
5.0E-06
6.0E-06
7.0E-06
8.0E-06
9.0E-06
1.0E-05LRF for operating
NPPs
Practical elimination of accident sequences
that could lead to large early radioactive
releases for new NPPs (NS-G-1.2)*
Core Damage Frequency (CDF) Large Release Frequency (LRF)
1/y
1/y
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CITATION FROM INSAG-12 ON SAFETY GOALS
25. For future NPPs, consideration of multiple failures and severe accidents will be achieved in a more systematic and complete way from the design stage. This will include improving accident prevention (for example, reduced common mode failures, reduced complexity, increased inspectability and maintainability, extended use of passive features, optimized human–machine interface, extended use of information technology) and further reducing the possibilities and consequences of off-site radioactive releases.
26. In the safety technology of nuclear power, overall risk is obtained by considering the entire set of potential events and their respective probabilities and consequences. The technical safety objective for accidents is to apply accident prevention, management and mitigation measures in such a way that overall risk is very low and no accident sequence, whether it is of low probability or high probability, contributes to risk in a way that is excessive in comparison with other sequences.
27. The target for existing NPPs L is a frequency of occurrence of severe core damage that is below about 10–4 events per plant operating year. Severe accident management and mitigation measures could reduce by a factor of at least ten the probability of large off-site releases requiring short term off-site response. Application of all safety principles and the objectives (of para. 25) to future plants could lead to the achievement of an improved goal of not more than 10–5 severe core damage events per plant operating year. Another objective for these future plants is the practical elimination of accident sequences that could lead to large early radioactive releases, whereas severe accidents that could imply late containment failure would be considered in the design process with realistic assumptions and best estimate analyses so that their consequences would necessitate only protective measures limited in area and in time.
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IAEA TECHNICAL MEETING ON
SAFETY GOALS IN APPLICATION
TO NUCLEAR INSTALLATIONS
TM Objective
● Provide international forum for presentations and discussions on the current practices in establishing and use of Safety Goals for nuclear installations
● To contribute to outlining the way forward
TM Summary
● Some 40 attendees from 23 countries and 5 international organizations -regulators, operators, designers, consultants, and TSOs
● 30 presentations and papers
● Two working groups:
WG1: General Framework for Safety Goals and Methodologies/Processes for Compliance Assessment
WG2: Process of Derivation of Low-Tier Quantitative Safety Goals and Qualitative and Quantitative Safety Goals Specification
● Questionnaire on national framework for Safety Goals with 20 responses
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OUTPUT
■ A formal TM report has
been produced
● Outputs of WGs
● Questionnaires responded
● Papers
● Conclusions and
recommendations for
IAEA activities
■ Producing guidance on
establishing and use of
Safety Goals recommended
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OBSERVATIONS
■ Surveys show that there is a variety of approaches
relating to establishment and use of Safety Goals in
Member States, which often include qualitative
considerations and quantitative risk metrics
■ Recent international projects on Safety Goals being
pursued by different expert groups [e.g. MDEP, WENRA,
Nordic PSA Group (NPSAG)] produced recommendations
■ Growing importance of establishing a technically
consistent holistic framework for Safety Goals for NPPs
and other nuclear installations on the basis of synergetic
consideration of qualitative concepts and quantitative risk
metrics
� Hierarchical structure
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RECOMMENDATIONS
Five areas were recommended by the TM where IAEA should
consider producing guidance (the formal TM report):
1. Develop a hierarchical approach for Safety Goals
2. Clarify interfaces between the Fundamental Safety
Objectives, Safety Principles, Safety Requirements and the
proposed framework for Safety Goals
3. Develop a methodology to derive lower-tier goals in a
consistent and coherent manner
4. Develop guidance on methods and approaches to assess the
degree of compliance with the full spectrum of Safety Goals and
a comprehensive review methodology
5. Develop an approach to using Safety Goals
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CONTINUED WORK AFTER TM APRIL 2011
■ A series of consultant meetings (2012-2013) to develop a draft
TECDOC -
“Development and Application of a Safety Goals Framework for
Nuclear Installations”
■ Overall Objective: to promote a greater harmonization of the use of
Safety Goals in Member States
■ Specific Objectives: to provide guidance for establishing a formal
framework for Safety Goals and compliance assessment______________
■ Drafting TECDOC - CM participants:• Irina Kuzmina (IAEA)
• Andy Ashworth (AECL, Canada)
• Heinz Peter Berg (BfS, Germany)
• Nigel Buttery (EdF Energy, UK)
• Michael Knochenhauer (Lloyd’s Register Scandpower, Sweden)
• Geoff Vaughan (ONR, UK)
• See-Meng Wong (NRC, USA)
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OUTLINE (1/2)
1. INTRODUCTION
2. DISCUSSION ON THE BACKGROUND AND BENEFITS OF A SAFETY GOALS
FRAMEWORK
● Safety Goals Definition
● A Framework for Safety Goals
● Relationship to IAEA Safety Standards
● Global Harmonisation
● Public Understanding and Communication
● Use of Safety Goals by Stakeholders
● Safety Goals Framework and Safety Performance Indicators
3. CHARACTERISTICS AND ASPECTS OF A SAFETY GOALS FRAMEWORK
● Considerations from the Technical Meeting, April 2011
● Safety Goals and IAEA Safety Standards Framework
● Safety Goals Framework Characteristics
● Aspects to be Considered in Developing a Safety Goals Framework
● Communication
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OUTLINE (2/2)
4. A GENERAL FRAMEWORK FOR SAFETY GOALS
● Basic Types of Safety Goals
● Hierarchical Approach to Safety Goals
5. DERIVATION OF SAFETY GOALS
● The Roles of Stakeholders Involved in the Definition of Safety Goals
● Safety Goals within the Framework
● Organising the Safety Goals defined within the Framework
6. APPLICATIONS OF A SAFETY GOALS FRAMEWORK
● Compliance Assessment
● Regulatory and Licensee Applications
● Use of the Safety Goals Framework in Integrated Risk Informed Decision Making
7. CONCLUDING REMARKS
APPENDIX 1 GLOSSARY
APPENDIX 2 SPECIFIC EXAMPLES OF SAFETY GOALS FRAMEWORK
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DEVELOPMENTS BY MULTINATIONAL DESIGN
EVALUATION PROJECT - MDEP
� The MDEP work attempted to set
out a hierarchical approach
● Top level = Fundamental Safety
Objective of the IAEA of protecting
people from radiation risks
● Second tier is based partly on the
basic defence-in-depth approach,
probably still to some extent
technology independent
● From the upper levels the
intention is to develop lower-level
goals, eventually technology
specific
Top
Level
Safety Goal
High Level Safety Goals
(DiD and Risk Goals)
Lower Level Safety Goals and Targets
(Deterministic and probabilistic)
Technology Specific Safety Targets
� Within MDEP, a group was tasked with considering how to harmonise Safety Goals
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HIERARCHY SUGGESTED IN NORDIC PSA GROUP
PROJECT - NPSAG
� As part of the NPSAG project on probabilistic Safety Goals, a hierarchy was suggested
� There are four levels :
● Society level (legislation expressing high-level requirements)
● Intermediate level (interpretation of legal requirements in a way that allows quantification)
● Technical level (quantitative requirements)
�High level (corresponding to PSA Level 1, 2 and 3)
� Low level (corresponding to safety systems and functions)
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HIERARCHICAL LEVELS OF SAFETY GOALS (1/4)
Level Formulation Notes
Top Level
Primary Safety Goal
Protecting people and the environment from harmful effect of ionizing radiation
Primary safety goal as set out in SF-1 (or society level safety goals as defined in national legislation or regulations)
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HIERARCHICAL LEVELS OF SAFETY GOALS (2/4)
Level Formulation Notes
Upper Level
Adequate Protection
Ensuring adequate protection in all operational modes of all facilities and installations at the site
Qualitative safety goals interpreting what is needed to ensure adequate protection
Includes interpretation of the top level safety goal in risk terms for accident conditions. This is often done by comparison with the levels of risks coming from other involuntary sources of risk
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HIERARCHICAL LEVELS OF SAFETY GOALS (3/4)
Level Formulation Notes
Intermediate Level
General Safety Provisions
Providing necessary safety provisions including technical and organizational measures based on proven approaches and good practices to ensure adequate protection
Technology-neutral site-wide safety goals based on proven approaches and good practices to achieve the upper level safety goals (e.g. definition of general requirements at site level)
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HIERARCHICAL LEVELS OF SAFETY GOALS (4/4)
Level Formulation Notes
Low Level
Specific Safety Provisions
Providing necessary specific safety provisions for all facilities and installations at the site
Technology and facility specific safety goals aimed at assuring that all nuclear installations/ facilities at the jointly meet the respective intermediate level safety goals
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An Example of Hierarchy of Safety Goals for Nuclear Installations
TOP LEVEL PRIMARY SAFETY GOAL: To protect people and the environment from harmful effects of ionizing radiation • Society-wide
UPPER LEVEL SAFETY GOALS: Ensuring adequate protection in all operational modes of all facilities and installations at the site • Society & site-wide
• Technology-neutral
Operational states Accident conditions
O1
To protect workers, the public and the environment
O2
To provide design
features for security
O3
To minimize
radioactive waste
O4
To provide design
features to facilitate
decommis-sioning
A1
Risk to life and health of people from the facilities and installations located at the site should be low comparing with
risk from other sources to which an individual is generally exposed
A2
Large off-site releases leading to land interdiction should be
practically eliminated
A3
Safety-security interface should be addressed
A4
Emergency response should be provided
INTERMEDIATE LEVEL SAFETY GOALS:
Providing necessary safety provisions including technical and organizational measures based on proven approaches and good practices to ensure adequate protection
• Site-wide
• Technology-neutral
Qualitative
O1-Q1 Management, leadership and safety culture
Deterministic quantitative
O1-D1 To meet ICRP
criteria for workers by providing adequate radiation protection
measures
K K K L Qualitative
A1-Q1 Maintaining effective
defence-in-depth
Deterministic quantitative
A1-D1 Maintaining
allowed doses for workers in DBAs
Probabilistic quantitative
A1-P1 Overall L(E)RF for the site for all events and
hazards
Qualitative
A2-Q1 Providing effective
SAM design features and SAMG
at the site level
Probabilistic quantitative
A2-P1 Probabilistic
interpretation of practically
eliminated for
land, site-level
A3-Q1 Vital area
identification at the
site level
A4-Q1 Detailed
emergency plan
O1-D2 To meet ICRP
criteria for discharges to the environment
by providing
adequate measures for controlling the
discharges
A1-Q2 Maintaining sufficient
safety margins
A1-D2 Maintaining
allowed discharges to the environment in
DBAs
A1-P2 Frequencies of external hazards/ magnitudes for design of site protective
features
A2-P2 Food ban
radioactivity levels and accepted
frequency
A4-D1 Food ban levels
A1-Q3 Providing sufficient
redundancy and diversity to comply with single failure criterion
A1-D3 Containment
withstanding the crash of a
specified size aircraft
A2-P3 Habitation
radioactivity levels and accepted frequency
A4-D2 Habitation
radioactivity levels
LOW LEVEL SAFETY GOALS: Providing necessary specific safety provisions for all facilities and installations at the site • Technology-specific
• Facility and installation-specific
K K K K Deterministic quantitative
A1-Q2-INST1(D1) – max fuel clad
temp. for INST1
A1-Q2-INST1(D2) – K for INST1
----------------------------------
A1-Q2-INST2(D1) – max fuel clad
temp. for INST2
A1-Q2-INST2(D2) – K for INST2
Probabilistic quantitative
• LERF for each installation:
A1-P1-INST1(LERF),
A1-P1-INST2(LERF),
• Supplemental goals on CDF as applicable:
A1-P1-INST1(CDF ),
Qualitative
A2-Q1-INST1(SAMG)
A2-Q1-INST2(SAMG)
Providing effective SAM design
measures and SAMG at the facility
level
A3-Q1-INST1
A3-Q1-INST12 K
Vital area identification at
facility level
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An Example of Hierarchy of Safety Goals for Nuclear Installations
TOP LEVEL PRIMARY SAFETY GOAL: To protect people and the environment from harmful effects of ionizing radiation • Society-wide
UPPER LEVEL SAFETY GOALS: Ensuring adequate protection in all operational modes of all facilities and installations at the site • Site-wide
• Technology-neutral
Operational states Accident conditions
O1
To protect workers, the public and the environment
O2
To provide design
features for security
O3
To minimize
radioactive waste
O4
To provide design
features to facilitate
decommis-sioning
A1
Risk to life and health of people from the facilities and installations located at the site should be low comparing with
risk from other sources to which an individual is generally exposed
A2
Large off-site releases leading to land interdiction should be
practically eliminated
A3
Safety-security interface should be addressed
A4
Emergency response should be provided
INTERMEDIATE LEVEL SAFETY GOALS:
Providing necessary safety provisions including technical and organizational measures based on proven approaches and good practices to ensure adequate protection
• Site-wide
• Technology-neutral
Qualitative
O1-Q1 Management, leadership and safety culture
Deterministic quantitative
O1-D1 To meet ICRP
criteria for workers by
providing adequate radiation protection
measures
K K K L Qualitative
A1-Q1 Maintaining effective
defence-in-depth
Deterministic quantitative
A1-D1 Maintaining
allowed doses for
workers in DBAs
Probabilistic quantitative
A1-P1 Overall L(E)RF for the site for all events and
hazards
Qualitative
A2-Q1 Providing effective
SAM design features and SAMG
at the site level
Probabilistic quantitative
A2-P1 Probabilistic
interpretation of
practically eliminated for land, site-level
A3-Q1 Vital area
identification at the site level
A4-Q1 Detailed
emergency plan
O1-D2 To meet ICRP
criteria for discharges to the environment
by providing adequate measures
for controlling the discharges
A1-Q2 Maintaining sufficient
safety margins
A1-D2 Maintaining
allowed discharges to the
environment in DBAs
A1-P2 Frequencies of external hazards/ magnitudes for design of site protective
features
A2-P2 Food ban
radioactivity levels and
accepted frequency
A4-D1 Food ban levels
A1-Q3 Providing sufficient
redundancy and diversity to comply with single failure criterion
A1-D3 Containment
withstanding the crash of a
specified size aircraft
A2-P3 Habitation
radioactivity levels and accepted frequency
A4-D2 Habitation
radioactivity levels
LOW LEVEL SAFETY GOALS: Providing necessary specific safety provisions for all facilities and installations at the site • Technology-specific
• Facility and installation-specific
K K K K Deterministic quantitative
A1-Q2-INST1(D1) – max fuel clad
temp. for INST1
A1-Q2-INST1(D2) – K for INST1
----------------------------------
A1-Q2-INST2(D1) – max fuel clad
temp. for INST2
A1-Q2-INST2(D2) – K for INST2
Probabilistic quantitative
• LERF for each installation:
A1-P1-INST1(LERF),
A1-P1-INST2(LERF),
• Supplemental goals on
CDF as applicable:
A1-P1-INST1(CDF ),
Qualitative
A2-Q1-INST1(SAMG)
A2-Q1-
INST2(SAMG)
Providing effective SAM design
measures and SAMG at the facility
level
A3-Q1-INST1
A3-Q1-INST12 K
Vital area
identification at facility level
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RECENT ACTIVITIES
■ Second Technical Meeting to review the preliminary draft TECDOC08-12 July 2013, Vienna, Austria
� A formal report produced
� The suggested structure is seen adequate + recommendations
� Helpful for developing countries (holistic view) & benchmarking the existing safety goals frameworks
� Wider informing the international community is useful
■ CMs: July 15-19, December 2-6, 2013� Addressing recommendations of the 2d TM
� Updated final draft soon
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ISSUES NEEDING FURTHER CONSIDERATION
‘Quantification’ is asked by Member States for the terms :
- Extremely unlikely
- High level of confidence
What should be the basis for these?
Practically eliminated:
The possibility of certain conditions occurring is
considered to have been practically eliminated if it is
physically impossible for the conditions to occur or if
the conditions can be considered with a high level of
confidence to be extremely unlikely to arise.
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Integrated Risk Informed Decision Making
• INSAG-25
• Guidance (TECDOC)
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� The Integrated Risk Informed Decision Making (IRIDM)
process is a structured process in which all the
insights and requirements relating to an operational,
safety or a regulatory issue are considered in reaching
a balanced and optimized decision
� The main goal of IRIDM is to ensure that any decision
which might affect nuclear safety is optimized without
unduly limiting the conduct of safe operation of the
nuclear power plant
IRIDM PROCESS
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EXAMPLES OF IRIDM APPLICATIONS
� An integrated approach can be applied to making decisions on operational and safety issues of a nuclear power plant
� These typically include
● Hardware Modifications & Procedural Changes
� Plant modifications and backfittings
� Emergency operating procedures
� Accident management measures, etc.
● Changes to Tech Specs (Operation Limits and Conditions)
� Optimization of on-line maintenance practices
� Changes to allowed outage times
� Optimization of testing intervals & arrangements
� Plant configuration management, etc.
● Exemptions from Tech Specs, etc.
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INSAG-25
INSAG-25 published in 2011
• Identifies the basic framework
• Sets out the principles for
application
• Define the key elements of
IRIDM
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IRIDM FRAMEWORK (INSAG-25)
Logical, reproducible, verifiable,
uncertainties addressed
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� Improved safety
● By taking each factor influencing safety into account in a
decision and its implementation
� Increased installation performance, operational
flexibility, cost effectiveness of operations
� Reduced radiation exposure
● By focusing maintenance on more risk-significant areas and
reducing unnecessary activities in high radiation areas
� Etc.
IRIDM BENEFITS
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TECDOC “IRIDM GUIDANCE”
� Objective: to suggest approaches to integrate the
results of DSA and PSA as well as other important
aspects to make sound, optimum, and safe decisions
● Follows the main principles presented in INSAG-25
● Provides detailed information/guidance on the key
elements of IRIDM and their integration
● Provides examples illustrating how the decisions can be
made or have been made using a structured IRIDM
process
● Explain issues not elaborated in the INSAG-25� Establishment of the IRIDM process
� Integration of inputs
� Treatment of uncertainties, etc.
� IAEA technical lead – A.Lyubarskiy, SAS/NSNI ([email protected])
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IRIDM FRAMEWORK (NEW TECDOC)
Examples (annexes)
Discussion on uncertainty
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IRIDM FRAMEWORK (NEW TECDOC)
Examples (annexes)
Discussion on unceratinty
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STRUCTURE OF THE TECDOC
1. INTRODUCTION
2. GENERAL OVERVIEW OF THE IRIDM PROCESS
3. DESCRIPTION OF THE IRIDM WORK FLOW
4. PREPARATION FOR THE ASSESSMENT OF THE INPUTS
5. ASSESSMENT, INTEGRATION AND DOCUMENTATION
6. APPROVAL, IMPLEMENTATION AND QUALITY ASSURANCE
7. SETTING UP A FORMAL IRIDM CAPABILITY
8. REFERENCES
ANNEXES 1 to 8 – EXAMPLES & DETAILED GUIDANCE
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SUMMARY
■ SAS/NSNI is currently developing two publications in
the IAEA-TECDOC series:
1. ‘Development and Application of a Safety Goals
Framework for Nuclear Installations’ and
2. ‘Integrated Risk Informed Decision Making Guidance’
■ Provide a structured, comprehensive and logical
framework and a process to promote making more
transparent and justifiable decisions to achieve
adequate protection of people and the environment
against radiation risks
■ Advanced development stage (publishing ~ end 2014)