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Information for stakeholders - 5. International Best Practice
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Under the ARPANS Act the CEO must, in deciding whether to issue a facility licence, take into account international best practice in relation to radiation protection and nuclear safety.
International best practice is not defined in the ARPANS Act. It is interpreted by ARPANSA as having regard to international standards as well as concepts and technologies implemented during construction and operation of facilities in countries with well-developed infrastructure for safety. It also includes relevant experience from the licensing, construction and operation of such facilities.
ARPANSA maintains information on its website on documents published by relevant international organisations3, which form part of international best practice.
This section briefly reviews international best practice frameworks and principles aimed at protecting the health and safety of people, and of the environment, from the harmful effects of radiation, with special emphasis on radioactive waste management.
A primary source for international best practice is the safety standards and security guidance issued by the IAEA. ARPANSA participates in the development of the safety standards through membership in the subject specific safety standards committees on radioactive waste safety; radiation safety; transport safety; nuclear safety; and emergency preparedness and response. ARPANSA also has a seat in the Commission on Safety Standards, which oversees and provides guidance on the work program of the safety committees. The Nuclear Security Guidance Committee oversees the development of nuclear security guidance, with the participation of ASNO and ARPANSA.
At the request of Member States, IAEA coordinates international reviews of a Member State’s governmental, legal and regulatory framework for safety, benchmarking the national framework against the IAEA safety standards and security guidance. An example is the Integrated Regulatory Review Service, with missions carried out to the Commonwealth of Australia (ARPANSA) in 2007 and 20114, and with a new mission to the Commonwealth and most state/territory jurisdictions planned for 2018.
The IAEA takes into account recommendations of the International Commission on Radiological Protection5 (ICRP) in its development of safety standards, as well as the scientific evaluations carried out by the United Nations Scientific Committee on the Effects of Atomic Radiation6 . ARPANSA plays a significant role in both these fora.
The IAEA safety standards comprise three tiers of regulatory documents. The top tier is the Safety Fundamentals, which states the safety objective:
The fundamental safety objective is to protect people and the environment from harmful effects of ionizing radiation.
The second tier comprises the Safety Requirements, with which compliance is expected. These are divided into General Safety Requirements (GSR) and Specific Safety Requirements (SSR). The Safety Guides that form the third tier provide guidance on how to satisfy the requirements.
Figure 3: The hierarchy of IAEA safety standards outlining the three tiers: Fundamentals; Requirements; and, Guides. Adapted from IAEA’s Strategy and Processes for the Establishment of IAEA Safety Standards, version 2.2, November 2015.
Similar to the safety standards, the Nuclear Security Series (NSS) follows a tiered structure. The top tier publication is the Fundamentals, Objective and Essential Elements of a State’s Nuclear Security Regime (NSS 20), published in 2013. It states the objective of a State’s nuclear security regime as follows:
The objective of a State’s nuclear security regime is to protect persons, property, society, and the environment from harmful consequences of a nuclear security event.
The second tier comprises a suite of recommendations, effectively corresponding to the requirements in the safety standards series.
Australia has also formally committed, in 2004, to the IAEA Code of Conduct on the Safety and Security of Radioactive Sources. Requirements on source security have been implemented in Australia through the Code of Practice for the Security of Radioactive Sources (RPS 11), published in 2007. This Code is mandated as a licence condition under the ARPANS Regulations. ARPANSA is also implementing the Supplementary Guidance on the Import and Export of Radioactive Sources.
The Joint Convention on the Safety of Spent Fuel Management and on the Safety of Radioactive Waste Management (the ‘Joint Convention’) was ratified by Australia in 2003. The objectives of the Joint Convention are as follows:
The Joint Convention includes provisions on establishment and maintenance of a legislative and regulatory framework to govern the safety of spent fuel and radioactive waste management, and to ensure that individuals, society and the environment are adequately protected against radiological and other hazards. These obligations extend to appropriate siting, design and construction of waste storage and disposal facilities and ensuring the safety of facilities both during their operation and after their closure.
The Joint Convention imposes obligations on Australia in relation to the trans-boundary movement of spent fuel and radioactive waste, and an obligation to take appropriate steps to ensure that disused sealed radiation sources are managed safely.
Australia, through ARPANSA, submits reports to the Secretariat of the Convention every third year, as an input to the review meetings carried out under the terms of the Convention. These reports are available on ARPANSA’s website7.
5.3.1. The Fundamental Safety Principles
The IAEA published its Fundamental Safety Principles8 in 2006, which include 10 safety principles. ARPANSA, in collaboration with state and territory regulators through the Radiation Health Committee, promotes the 10 principles nationally in Australia in accordance with Fundamentals for Protection Against Ionising Radiation (RPS F-1).
The Fundamental Safety Principles (RPS F-1)
The prime responsibility for management of radiation risks must rest with the person or organisation responsible for facilities and activities that give rise to radiation risks.
Measures for controlling radiation risks must ensure that no individual bears an unacceptable risk of harm, and that the environment is protected.
An effective framework including legislation, regulation and guidance to promote management of radiation risks, including an independent regulatory body, must be established and sustained.
People and the environment, present and future, must be protected against radiation risks.
Effective leadership and management of radiation risks must be established and sustained in organisations concerned with, and facilities and activities that give rise to, radiation risks.
All practical efforts must be made to prevent and mitigate accidents, and acts with malicious intent, that may give rise to radiation risks.
Facilities and activities that give rise to radiation risks must yield an overall benefit.
Arrangements must be made for emergency preparedness and response for incidents, accidents and malicious acts that may give rise to radiation risks.
Protection must be optimised so that radiation risks are as low as reasonably achievable.
Protective actions to reduce existing or unregulated radiation risks must be justified and optimised.
5.3.2. Defence in Depth
The concept of defence in depth applies to the protective capability of a facility through a hierarchy of controls and engineering features that perform safety functions independently of each other. Failure of one component of the system should not jeopardise protection of the health and safety of people, and of the environment.
The defence in depth concept was introduced for nuclear facilities several decades ago, and comprises five levels of objectives and controls, as outlined in Table 1 (see the International Nuclear Safety Advisory Group [INSAG] publication Defence in Depth in Nuclear Safety, INSAG-10).
|Level of defence in depth||Safety objective||Essential means to achieve the objective|
|Level 1||Prevention of abnormal operation and failures||Conservative design and high quality in construction and operation|
|Level 2||Control of abnormal operation and detection of failures||Control, limiting and protection systems and other surveillance features|
|Level 3||Control of accidents within the design basis||Engineered safety features accident procedures|
|Level 4||Control of severe plant conditions, including prevention of accident progression and mitigation of the consequences of severe accidents||Complementary measures and accident management|
|Level 5||Mitigation of radiological consequences of significant release of radioactive materials||Off-site emergency response|
Table 1: The five levels of defence in depth. Based on INSAG-10.
Commonly, containment of waste is accomplished by multiple physical barriers where the barrier functions are associated with the physical and chemical properties of the waste matrix (e.g. concrete, glass or ceramics), the waste packages and overpacks, material used to backfill a disposal facility, and the environment surrounding the facility.
The importance of multiple safety functions is emphasised in the IAEA Specific Safety Requirements No. SSR-5 Disposal of Radioactive Waste.
Through application of the defence in depth concept to a facility for radioactive waste storage or disposal, the radioactive substances can be effectively contained and isolated from the surrounding environment. If properly designed, constructed and operated, this will reduce radiation exposure in the vicinity of the facility to extremely low levels.
5.3.3. Radiation Protection Principles
The international framework for radiation protection rests on three principles, justification, optimisation and dose limitation, outlined in the 2007 Recommendations of the International Commission on Radiological Protection in its Publication 103. These principles are also reflected in the IAEA’s General Safety Requirements No GSR Part 3: Radiation Protection and Safety of Radiation Sources: International Basic Safety Standards9 and are considered in licensing decisions under the ARPANS Act and Regulations.
Conclusions as to whether an activity is justified can sometimes be a professional judgement, for example when assessing whether the benefit from a medical procedure involving radiation outweighs its associated risks. In other cases, the benefit is a societal judgement where decisions on justification rest with government.
The overarching principle for protection (once an activity has been deemed justified), is that of optimisation, which provides an effective means of reduction of radiation exposures. Optimisation of protection in research facilities and industry will, other than in rare instances, lead to actual exposures that are far below the statutory limits for both workers and members of the public and will cause no harm to the health of the environment.
|Source of exposure||Percentage||mSv|
|Radon and progeny||6%||0.2|
|Potassium-40 in the body||6%||0.2|
|Uranium/Thorium in the body||6%||0.2|
The exposures in the above table are given in the quantity effective dose, which is a risk-related quantity used for radiation protection (not for detailed risk estimation) that takes into account the properties of different types of radiation and sensitivities of different organs in the human body. It is measured in the unit sievert (Sv), normally as millisievert (mSv).
The radiation protection framework applies to planned exposure situations (where radiation protection can be planned in advance to manage activities that may lead to radiation exposure), emergency exposure situations (loss of control of a source or facility due to accidents or acts with malicious intent) and existing exposure situations (where the exposure already exists at the time a decision on control has to be taken, including exposure during recovery from emergencies).
Storage and disposal of radioactive waste are managed as planned exposure situations. The justification of a waste management facility has to be judged in connection with the activity that generates the waste. However the justification for past activities that have generated waste currently in storage, whether these activities were carried out under a licence or not, cannot be reassessed when decisions have to be made regarding its management. The ICRP considers this aspect in Publication 122:
Under circumstances where barriers perform as planned, containment of the waste should provide for isolation of the waste from the surrounding environment for long periods of time which leads to exposure of members of the public that are very low or effectively zero. Actual measurements of exposure would be very difficult and would not allow separation of the (possible) exposure from the facility from exposure emanating from natural sources. Likewise, detection of radioactive substances in the environment may not be feasible.
For the purpose of radiation protection of the public, the exposure analysis will have to be based on simulations using a real or hypothetical representative individual (or person) as the subject of the exposure calculations, as detailed in ICRP Publication 101a.
In some cases human error, negligence or reckless behaviour; or events such as natural disruptive events, accidents or acts with malicious intent, may cause higher exposures. The defence in depth measures are intended to, as far as is reasonably practicable, reduce the likelihood that such potential exposures occur and limit the consequences should they occur.
The likelihood of harm from disruptive events and accidents may be best approached by using the concept of risk. The risk is made up of two components: the probability that an event occurs over a certain period of time; and the consequence in terms of health of people and the environment should this event occur. An event that has a high probability to occur but where the consequences are minor may carry a similar risk as an event that is very unlikely to occur but with more severe consequences.
For longer time periods credible analysis of actual radiation risks becomes increasingly difficult to perform. While an analysis over long-term is still useful and promotes an understanding of the protective capability of the facility, actual estimates of risk become uncertain. This is because of uncertainty in the long-term performance of the barriers and uncertainties in the assumptions on evolution of the site, including future land use, demographics and societal circumstances.
The effectiveness of protective measures in mitigating exposures is correspondingly difficult to estimate. The protective capability under such circumstances is promoted by the application of best available technique or BAT (see ICRP Publication 122). This is an internationally recognised practice in management and disposal of waste and particularly relevant when assessing long‑term safety under conditions where radiation risks are difficult to quantify or very uncertain. BAT refers to the preferred technology for managing and disposing of radioactive waste, selected from among others after taking into account factors related to technology, economics, public policy, and other parameters such as the nature of the site.
Radiation protection also considers protection of the environment, specifically the populations of organisms that inhabit the natural environment. There are no established dose limits for such organisms. Ranges of environmental dose rates have been identified, based on our knowledge of radiation effects, where there may be a risk of some detrimental effects on populations of organisms in the environment (ICRP Publications 108 and 124). These ‘environmental reference levels’ of exposure can guide optimisation efforts. Further guidance that builds on international best practice is available in ARPANSA’s Guide for Radiation Protection of the Environment (RPS G-1).
5.3.4. Safety Analysis and Safety Assessment
The understanding of safety of the facility is gained through performing a safety analysis. The safety analysis is the evaluation of the potential hazards associated with a facility or an activity. The formal safety analysis is part of the overall safety assessment, i.e. it is part of the systematic process that is carried out throughout the design process (and throughout the lifetime of the facility or the activity) to ensure that all the relevant safety requirements are met by the proposed (or actual) design.
This also requires analysis of uncertainties which may be large, in particular in relation to long‑term protective capability and sensitivities, i.e. what are the most significant elements of the safety analysis that determine our overall understanding of safety.
The relationship between the safety analysis and the safety assessment in understanding the performance of the facility is explained in the IAEA General Safety Requirements No. GSR Part 4 (Rev 1), Safety Assessment for Facilities and Activities, published in 2016.
Figure 4: Interaction between different elements of the safety assessment, illustrating the iterative nature of the process which allows for feedback and gradual refinement as a project evolves. Adapted from IAEA Safety Requirements No. GSR Part 4 (Rev 1), Safety Assessment for Facilities and Activities.
5.3.5. The Safety Case
The available knowledge and information on the performance of storage and disposal facilities will evolve with time and through the different licensing stages. In particular, successive safety assessments and the operational experience will be important for improved understanding of the performance of a disposal facility after closure, and after the period of active institutional control.
The information will be collated in a safety case for the facility. The safety case is the collection of scientific, technical, administrative and managerial arguments and evidence in support of the safety of a facility covering the suitability of the site and the design, construction and operation, the assessment of radiation risks, and assurance of the adequacy and quality of all of the safety related work that is associated with the facility.
The safety case, with its supporting safety assessment, provides the basis for demonstration of safety and for licensing. It will evolve with the development of the facility. For each of the principal stages of the licensing process, an updated safety case is required. The safety case must demonstrate that throughout the facility’s life, the facility will comply with the statutory radiation dose limits and explicitly describe how radiation exposures will be kept as low as reasonably achievable (ALARA). The safety case includes the operational limits and conditions within which the facility must operate, and a safety analysis that is documented in a safety analysis report.
For a disposal facility, the safety case provides an understanding of the behaviour of the facility under normal conditions and disruptive events over the time frames where the radioactive waste poses risks to the health and safety of people, and of the environment.
The safety case will be the main basis on which dialogue with interested parties will be conducted and on which confidence in the safety of the disposal facility will be based. Stakeholders can contribute valuable knowledge and input in developing the safety case. Their involvement and contributions during consultation form part of the safety case development process, and must be documented in the safety case.
The requirements for a safety case for predisposal facilities are stated in the IAEA General Safety Requirements No. GSR Part 5 Predisposal Management of Radioactive Waste, and for disposal facilities in the Specific Safety Requirements No. SSR-5 Disposal of Radioactive Waste.
Detailed guidance on the content of the safety case is given in the IAEA Specific Safety Guide No. SSG-23, The Safety Case and Safety Assessment for the Disposal of Radioactive Waste; and in the IAEA General Safety Guide No. GSG-3, The Safety Case and Safety Assessment for the Predisposal Management of Radioactive Waste.
5.3.6. Management System
The arrangements put in place to establish a facility, and the interdependencies between such arrangements, should be consolidated and documented in a management system. A management system designed to support the achievement of the object of the ARPANS Act will integrate safety, health, environmental, security, quality, societal and economic elements. The management system shall ensure that international best practice is taken into account in such arrangements and promote a culture of safety. The General Safety Requirements No. GSR Part 2, Leadership and Management for Safety sets out, among other things, the following:
One of the features of a management system is to allow for resources to be directed to areas where the safety outcome can be anticipated to be greatest. A graded approach to management of safety will ensure the efficient and effective use of available, and often limited, resources.
Human error is a main contributor to events that may be of safety significance or lead to accidents. A number of contributing factors to such errors can be identified. These include inadequate training, lack of managerial support, poor reporting practices, complacency, neglect and others.
Safety is not implemented effectively if managers and workers do not approach it with the right mindset. A culture of safety shall be an integral component of all activities. A good safety culture cannot be imposed but needs to be continually fostered, where the role modelling of managers is a prerequisite for success.
ARPANSA uses the concept of holistic safety (or systems safety) in order to analyse, and to provide advice on, integration of different components that contribute to overall safety. These include technology; the organisational elements of the operating organisation and the responsibilities that supports safety; and the approach and perceptions around safety of individual members of staff at all levels.
Figure 5: The components of holistic safety. Source: ARPANSA.
8 Jointly sponsored by the European Atomic Energy Community, the Food and Agriculture Organization of the United Nations, the International Atomic Energy Agency, the International Labour Organization and the International Maritime Organization.
9 Jointly sponsored by the European Commission, the Food and Agriculture Organization of the United Nations, the International Atomic Energy Agency, the International Labour Organization, the OECD Nuclear Energy Agency, the Pan American Health Organization, the United Nations Environment Programme and the World Health Organization.