RWMC Regulators' Forum (RWMC-RF)

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1 For Official Use NEA/RWM/RF(2008)3/PROV NEA/RWM/RF(2008)3/PROV For Official Use Organisation de Coopération et de Développement Economiques Organisation for Economic Co-operation and Development 13-Feb-2008 English - Or. English NUCLEAR ENERGY AGENCY RADIOACTIVE WASTE MANAGEMENT COMMITTEE RWMC Regulators' Forum (RWMC-RF) PRELIMINARY LITERATURE REVIEW ON: 'OPTIMISATION AND BEST AVAILABLE TECHNIQUES FOR GEOLOGICAL REPOSITORIES' This document supports Item 5.d of the RF meeting agenda of March The RF is asked to rereview/comment on it with a view to support the Japan workshop and possibly finalise the paper or a publication thereafter. The intention is to achieve, in due course, a common understanding of what is meant by the requirements of Optimisation and BAT as well as to reflect on possibilities and limits in their application during a repository development process. For any questions concerning this document please contact: claudio.pescatore@oecd.org English - Or. English JT Document complet disponible sur OLIS dans son format d'origine Complete document available on OLIS in its original format

2 TABLE OF CONTENTS EXECUTIVE SUMMARY INTRODUCTION Aim and outline of the present document The structure of the document INTERNATIONAL RECOMMENDATIONS Optimisation of Protection ICRP recommendations IAEA safety standards Joint Convention Best Available Techniques IPPC Directive ICRP ALARP Environmental Impact Assessment Lessons learnt from international recommendations NATIONAL REGULATION AND GUIDANCE Sweden SSI FS SSI FS United Kingdom Environment Agency regulation France Conclusions on national regulation and guidance IMPLEMENTATION OF BAT IN NATIONAL PROGRAMMES AND EXPERIENCE FEEDBACK Application of BAT in safety cases and individual programmes Feasibility of implementation as planned Demonstration that system can be implemented with existing technology - new development required? Experience feedback from practical implementation of optimisation and BAT in Sweden The recurrent risk calculations should consider alternative options BAT focuses on performances of individual components of the repository system Possible conflict between BAT and optimisation... 23

3 4.4.4 Difficulties to define a priori criteria for optimisation and BAT Role of the stepwise approach Societal and economical constraints for the application of optimisation and BAT BAT and future human action CONCLUSIONS KEY ISSUES FOR CONSIDERATION IN FUTURE WORK ON REGULATORY GUIDANCE

4 EXECUTIVE SUMMARY The evolution over time of the international guidance on geologic disposal of solid longlived radioactive waste demonstrates an evolving understanding of long term implications. This is related to the recognition that dose and risk, as measures of detriment, cannot be forecast with any certainty beyond a few hundred years and are therefore only indicators of protection afforded by the disposal system. Risk analyses for geological repositories will always be associated with uncertainties, especially for distant time periods after closure. There is therefore a need for a high level of shared confidence in the safety case (or license application) to convince the regulator and to support decision-making. In this context it is more and more recognised that the use of performance indicators in addition to dose and risk, the application of constrained optimisation and the demonstration of the use of Best Available Techniques (BAT), including sound engineering and managerial principles can all contribute to regulatory decision making and help guarantee the future acceptability of current decisions. There is a de facto lack of guidance on how optimisation requirements can be implemented during the stepwise decision making process accompanying the development of a disposal project that may take several decades to complete. Against this background, the Core Group of the RF has identified optimisation and BAT among the issues that present particular challenges in licensing. The IGSC and the LTSC group have reached similar conclusions. The present document aims at identifying the main issues that would present particular challenges to licensing and would deserve regulatory foresight and guidance. The analysis is supported by a literature review striving to scope the issues from regulator and implementer perspective, so that it can serve both communities. An extensive review of recommendations relative to the different forms of optimisation and BAT is documented, including the ICRP, the IAEA and the Integrated Prevention, Pollution and Control (IPPC) Directive of the European Commission. It is apparent that optimising protection of the environment and the public relies, in large part, on sound engineering and managerial principles and to the process of deciding between alternative sites and design options. It seems however that there is a need for additional guidance on the specific methods to be used in making these comparisons. As a result there is a considerable variability in how complementary indicators are required in regulation and applied in safety cases, and in how their relative importance and utility is seen to change with time scale. 4

5 As for the relative merits of the different forms of optimisation it is evident that the practical implementation of both constrained optimisation and BAT do not differ significantly. They both lead to a stepwise approach where objectives for optimisation are clarified along the process. Both constrained optimisation and BAT apply throughout the site selection and design development process. The main difference is that the use of best available techniques tends to focus on optimising each component of the system from the perspective of avoiding or delaying releases, whereas ALARA tends to focus more on the overall performance of the disposal system. This may lead to the introduction of specific requirements on the geological barriers and engineered barriers. Some difficulties may arise from the interpretation of the term best and how it can be applied for site and design selection. There is a danger that this may lead to an open-ended process leading to significant delays in decision-making. The priority given to considering optimisation and BAT in national programmes varies from country to country. Many programmes are at a stage where the focus is on demonstrating the existence of technical solutions, but do not want to irrevocably freeze them. As a result, and although safety is a major criterion, the process of optimisation is ongoing, even for those programmes that are most advanced. Depending on the progress made in knowledge, ways of improvement are possible and could be developed in later phases of the projects. Considering the international recommendations on the subject and the central role of optimisation for compliance in the long time frames it seems important that national regulations provide guidance based on these recommendations. Given the stepwise decision making process regulatory decisions about optimisation and BAT should be made at each important step of the programme and not only at the time of a license application. At earlier stages, the discussion of optimisation and BAT and how they are managed and documented is a framework for discussing feedback to remaining development needs. The difficult task of the regulator is to define, early before licensing, this regulatory framework. There are many recommendations on the subject at the international and national level. But the use of the terminology is not always consistent and there are significant gaps that remain in terms of how to implement and evaluate them in practice. In this context, future regulatory work on the subject may concentrate on the following issues: Can a standard definition for optimisation, BAT, and ALARA/ALARP be developed? What are the differences between these principles namely in their practical implementation? Is one a subset of the others, or do they have fundamentally different goals or measurement endpoints? Do these principles apply over the same timeframes and spatial scales? Are there differences (and what are they) in how these concepts are applied at different 5

6 phases in repository development (e.g., siting, design, construction, operation, monitored post-closure period )? Can they conflict, and if so, how should the conflict be resolved? How are they to be implemented in the course of a stepwise development (and stepwise licensing and review) process? Can optimisation ever be considered complete? When? At what point are decisions frozen? Can they be revisited? When and how? Which are the factors and criteria to consider in assessing competing options for design? What is the meaning of available in a project running over several decades? Should formal quantitative methods for optimisation be used? And in this case how to balance decisions on conflicting requirements coming from the need to reduce impacts associated with different types of scenarios? How to balance decisions that might have competing implications for long-term protection versus short-term protection including operational safety? How best to report on optimisation and BAT considerations in a safety case/license application? How to factor cost into the implementation of both BAT and optimisation? 6

7 1. INTRODUCTION The evolution over time of the international guidance on geological disposal of solid long-lived radioactive waste demonstrates an evolving understanding of long term implications. This is related to the recognition that dose and risk, as measures of detriment, cannot be forecast with any certainty beyond a few hundred years and are therefore only indicators of protection afforded by the disposal system. Risk analyses for geological repositories will always be associated with uncertainties, especially for distant time periods after closure. These uncertainties are related to evolution of climate, biosphere conditions and human society but also due to incomplete site data and the need for the extrapolation of today s measurements and models to these long time frames. Further it may not be possible to check the results of the performance assessment calculations thousands of years into the future nor to undertake remediation activities. There is therefore a need for a high level of shared confidence in the safety case (or license application) to convince the regulator and to support decision-making. In this context it is more and more recognised that the use of performance indicators in addition to dose and risk, the application of constrained optimisation and the demonstration of the use of Best Available Techniques (BAT), including sound engineering and managerial principles can all contribute to regulatory decision making and help guarantee the future acceptability of current decisions. There is, however, considerable variability in how these complementary approaches or indicators are applied, and in how their relative importance and utility is seen to vary with time scale. The regulator is typically faced with the following questions: How can we know that the proponent has done as good job as reasonably possible? Has the proponent taken into consideration all practicable means of improving the repository performance? It is in this context that the principles of optimisation and BAT are important regulatory (and societal) tools! This is an area where continued discussion and exchange of views would be enlightening. There is a de facto lack of guidance on how optimisation requirements can be implemented in practice in repository development. In particular, the implementation of a disposal project has come to be viewed as an incremental process, perhaps taking several decades to complete. This vision involves intermediate steps at which approval of the project is to be received by the authorities, which implies the protection of future generation, and also assumes their involvement in the process and a need to preserve their ability to exercise choice. How are then optimisation and BAT going to apply in the present decision making context? Against this background, the Core Group of the RF has identified optimisation and BAT among the issues that present particular challenges in licensing. The IGSC and the LTSC group have reached similar conclusions. The IGSC is asking the RF specifically to deal with these issues. (See Annex) 7

8 1.1 Aim and outline of the present document Given the high interest of the implementers and regulators in the topic of optimisation and BAT, there is a consensus to try to define better what would be the aspects of most relevance for developing regulation on this topic with input from a broad range of programmes. The present document aims at identifying the main issues that would present particular challenges to licensing and would deserve regulatory foresight and guidance. The document is supported by a literature review striving to scope the issues from regulator and implementer perspective, so that it can serve both communities. An extensive review of recommendations relative to the different forms of optimisation and BAT is documented, including the ICRP, the IAEA and the Integrated Prevention, Pollution and Control (IPPC) directive of the European Commission. Some examples of issues considered in the document are as follows: - Is there a common understanding of the international guidance used in the context of optimisation and BAT (constrained optimisation, sound engineering, BAT, ALARP ) and of its implications in practical terms? - Are there requirements or guidance associated to the different forms of optimisation and BAT in documents from international organisations (ICRP, IAEA, EC) and in national regulations? What is the practical distinction between optimisation and BAT? - What could be the role of optimisation and BAT in the stepwise decision making process and the expectations from the regulator to the implementer at key steps of the development process? - What could be the most critical challenges for the implementer? - How do experience feedback in other radiation protection and environmental protection fields and guidance on EIA and QA management contribute to implement optimisation and BAT in regulation and guidance for geological disposal? - Which are the key issues to consider in future work toward developing practical regulatory guidance. In particular what are the factors to consider for optimisation and how are they balanced? 1.2 The structure of the document The structure of the document is as follows: - Review and lessons learnt from international recommendations; - Review of national regulation and guidance; - Lessons learnt from implementation of national regulations; - Conclusions; - Key issues for consideration in future work and definition of priorities. 8

9 2. INTERNATIONAL RECOMMENDATIONS 2.1 Optimisation of Protection ICRP recommendations Definition of constrained optimisation and ALARA The ICRP has developed a system of radiological protection that applies to all practices involving radioactive material. This system is based on application of the principles of justification of a practice, of optimisation of protection and of limitation of doses. The principle of optimisation of protection is expressed as follows (ICRP 60): In relation to any particular source within a practice, the magnitude of individual doses, the number of people exposed and the likelihood of incurring exposures where these are not certain to be received should all be kept as low as reasonably achievable, economic and social factors being taken into account (ALARA principle). This procedure should be constrained by restrictions on the doses to individuals (dose constraints), or on the risks to individuals (risk constraints) so as to limit the inequity likely to result from the inherent economic and social judgments. (The optimisation of protection) Application to the disposal of solid radioactive waste In connection with the specific problems associated with the long term, the ICRP has then elaborated the application of the system of radiological protection to the disposal of solid radioactive waste in its publications 77 and 81 and has issued the following recommendations: - Constrained optimisation is the central approach to evaluating the acceptability of a disposal system of radioactive waste: Application of dose limits to long-lived solid radioactive waste disposals has intrinsic difficulties because of the potential public exposure in the long term. The principal means of achieving protection of the public is through a process of constrained optimisation that will obviate the direct use of the public exposure dose limits in the control of radioactive waste disposal. - Formal optimisation techniques for application to potential exposure remain to be developed: Optimisation of protection against potential exposure is still largely unresolved particularly when probabilities are low and consequences are big. - Optimisation is therefore a judgemental process: In the context of radioactive waste disposal, optimisation is a judgmental process with social and economic factors being taken into account and should be conducted in a structured essentially qualitative way. The optimisation principle should be applied in an 9

10 iterative manner during the disposal system development process and should particularly cover both the site selection and the repository design phases. - Optimisation is not an open-ended process and is connected to the issue of the application of technical and managerial principles: Judgment is required in the optimisation of protection and in the application of technical and managerial principles. More specifically, in the Commission s view provided that reasonable measures have been taken both to satisfy the constraints for natural processes and to reduce the probability or the consequences of inadvertent human intrusion and that technical and managerial principles have been followed, then radiological protection requirements can be considered to have been complied with. The ICRP elaborates on technical and managerial principles As indicated above, application of technical and managerial principles are part of the compliance requirements to judge on the radiation protection of the disposal system. ICRP 81 recommends that technical and managerial principles be used for potential exposure situations during the disposal system development process to enhance confidence that radiation safety will be maintained during post-closure. Complying with these principles includes application of: defence in depth, margins of safety, passive safety, multiple barriers, sound engineering principles and practices, codes and standards, comprehensive system of quality assurance, trained and qualified personnel, peer reviews, transparency and openness to public participation. They include as well requirements for the safety case: comprehensiveness, multiple lines of reasoning, good understanding, documentation on application of technical and managerial principles IAEA safety standards Safety fundamental SF 1 (2006) The safety fundamental SF1 elaborates on the requirement for optimisation, on the stepwise approach for optimisation and on the factors to take into account for optimisation. SF1 requires optimisation of protection in its principle 5: Principle 5: Optimisation of protection Protection must be optimized to provide the highest level of safety that can reasonably be achieved. Stepwise management is recommended: To determine whether radiation risks are as low as reasonably achievable, all such risks, whether arising from normal operations or from abnormal or accident conditions, must be assessed (using a graded approach) a priori and periodically reassessed throughout the lifetime of facilities and activities. Where there are interdependencies between related actions or between their associated risks (e.g. for different stages of the lifetime of facilities and activities, for risks to different groups or for different steps in radioactive waste management), these must also be considered. Account also has to be taken of uncertainties in knowledge. 10

11 The factors to consider for optimisation are listed : The optimisation of protection requires judgments to be made about the relative significance of various factors, including: The number of people (workers and the public) who may be exposed to radiation; The likelihood of their incurring exposures; The magnitude and distribution of radiation doses received; Radiation risks arising from foreseeable events; Economic, social and environmental factors. The optimisation of protection also means using good practices and common sense to avoid radiation risks as far as is practical in day to day activities. Safety requirements for geological disposal of radioactive waste WS-R-4 (2006) WS-R-4 elaborates on application of ICRP recommendations on geological disposal of radioactive wastes. Emphasis is given on use of sound technical and managerial principles and optimisation requirements for operational and post-closure safety. Sound technical and managerial principles: The safety of a geological disposal facility after closure relies on the combination of the site features and the quality of facilities design as well as that of the waste packages and on the proper implementation of the design. Ensuring the required level of safety and quality entails developing the geological disposal facility in an integrated manner, on the basis of sound scientific understanding, good engineering, the application of sound technical and managerial principles, thorough and robust safety assessments with the application of quality assurance to all of these elements. A stepwise approach allows the development of the understanding and of the assessment of uncertainties. Radiological protection and optimisation Operational period The primary goal is to ensure that radiation doses are as low as reasonably achievable. The optimisation of protection is required to be considered in the design of geological disposal facility and in the planning of operations above and below ground. These requirements are the same as of any licensed facility. Post-closure period Objective: Geological disposal facilities are to be sited, designed, constructed and closed so that protection in the post-closure period is optimized social and economic factors being taken into account and a reasonable assurance is given that doses and risks to members 11

12 of the public in the long term will not exceed the dose or risk level that was used as a design constraint. Constrained optimisation is the central approach adopted to ensure the radiological safety of a waste disposal facility (ICRP 81). In this context, the optimisation of protection is a judgmental process with social and economic factors being taken into account, and it should be conducted in a structured but essentially qualitative manner, supported by quantitative analysis. Close connection is made between optimisation and application of sound engineering and managerial techniques: The optimisation of protection for a geological disposal facility is a judgmental process that is applied to the decisions made during the development of the facility s design. Most important is that sound engineering and technical solutions are adopted and sound principles of quality management are applied throughout the development operation and closure of the geological disposal facility. Given these considerations, protection can then be considered optimized provided that: Due attention has been paid to the long term implications of various design options at each step in the development and operation of the geological facility ; There is a reasonable assurance that the assessed doses and/or risks resulting from the generally expected range of the natural evolution of the disposal system do not exceed the appropriate constraint, other time frames for which the uncertainties are not so large as to prevent meaningful interpretation of the results ; The likelihood of events that might disturb the performance of the geological disposal facility so as to give rise to higher doses or risks has been reduced as far as is reasonably possible by the siting or design. Understanding of the relevance and implication for safety Throughout the development of a geological disposal facility an appropriate understanding of the relevance and implication for safety of the available options shall be developed by the operator with the ultimate goal of providing an optimized level of operational and post-closure safety. Alternative management options Safety assessments support judgements with regard to alternative management options as an element of optimizing protection and safety Joint Convention The Joint Convention introduces a requirement on optimisation of protection: Each Contracting Party shall take the appropriate steps to ensure that during the operating lifetime of a spent fuel or radioactive waste management facility: 12

13 the radiation exposure of the workers and the public caused by the facility shall be kept as low as reasonably achievable, economic and social factors being taken into account. 2.2 Best Available Techniques This concept has been developed by the European legislation in the Integrated Prevention, Pollution and Control (IPPC) Directive and considered by the ICRP IPPC Directive In the general principles governing the basic obligations of the operator article 3 reads: Member States shall take the necessary measures to provide that the competent authorities ensure that installations are operated in such a way that all the appropriate preventive measures are taken against pollution, in particular through application of the best available techniques Best available technique is defined as follows: 'Best available techniques` shall mean the most effective and advanced stage in the development of activities and their methods of operation which indicate the practical suitability of particular techniques for providing in principle the basis for emission limit values designed to prevent and, where that is not practicable, generally to reduce emissions and the impact on the environment as a whole : 'techniques shall include both the technology used and the way in which the installation is designed, built, maintained, operated and decommissioned, 'available techniques shall mean those developed on a scale which allows implementation in the relevant industrial sector, under economically and technically viable conditions, taking into consideration the costs and advantages, whether or not the techniques are used or produced inside the Member State in question, as long as they are reasonably accessible to the operator, 'best shall mean most effective in achieving a high general level of protection of the environment as a whole ICRP The ICRP 77 mentions that the term best available technology under prevailing circumstances is often used in connection with optimisation. There has been increasing pressure for the adoption of policies described by labels such as best available technology or best available technology not entailing excessive cost. The term best available has usually implied best from the environmental viewpoint regardless of cost. Costs are involved when they are becoming excessive. ICRP thinks that these policies fall short of achieving the optimisation of protection. However, using the best available technology may turn out to be advantageous for specific purposes, such as reducing doses to the natural environment where no method for quantitative assessment of detriment is available. 13

14 2.3 ALARP ALARP stands for As Low As Reasonably Practicable, and is a term often used in the milieu of safety-critical and high-integrity systems. The ALARP principle is that the residual risk shall be as low as reasonably practicable. For a risk to be ALARP it must be possible to demonstrate that the cost involved in reducing the risk further would be grossly disproportionate to the benefit gained. The ALARP principle arises from the fact that it would be possible to spend infinite time, effort and money attempting to reduce a risk to zero. It should not be understood as simply a quantitative measure of benefit against detriment. It is more a best common practice of judgement of the balance of risk and societal benefit. The ALARP principle is mainly used in the UK. Outside the UK the ALARP principle is often not used; instead standards and 'good engineering practice' are adhered to. 2.4 Environmental Impact Assessment European Directive 97/11/EC This Directive shall apply to the assessment of the environmental effects of those public and private projects which are likely to have significant effects on the environment. The information to be provided by the developer shall include at least: a description of the project comprising information on the site, design and size of the project, a description of the measures envisaged in order to avoid, reduce and, if possible, remedy significant adverse effects, the data required to identify and assess the main effects which the project is likely to have on the environment, an outline of the main alternatives studied by the developer and an indication of the main reasons for his choice, taking into account the environmental effects, a non-technical summary of the information mentioned in the previous indents. 2.5 Lessons learnt from international recommendations From the above compilation one could ask the question how constrained optimisation ALARA, ALARP and application of best available technique differentiate from each other and complete each other. In the international texts derived from ICRP recommendations on radiological protection of human beings (including IAEA standards) the terms ALARA and optimisation (or constrained optimisation) are used. These requirements refer to the need to keep doses to human beings down to a level that is as low as reasonably achievable, economic and social factors being taken into account. Since there appears to exist, however, no comprehensive guidance on how best fulfil these requirements, it is difficult to differentiate them. 14

15 One should recognize first that application of these requirements to geological disposal programmes are central to providing confidence that protection of the public has been achieved because of intrinsic difficulties associated with the long term. These requirements will also contribute to regulatory decision making and help guarantee the future acceptability of current decisions. They are thus very much connected with the stepwise development of a waste disposal facility and introduce the necessary flexibility in considering concerns from members of the public. The optimisation of protection has the broad interpretation of doing all that is reasonable to reduce doses. This implies maximizing the margin of good over harm by reducing the harm. The basic role of optimisation of protection is to engender a state of thinking in everyone responsible for control of radiation exposures such that they are continually asking themselves the question: Have I done all that I reasonably can to reduce these radiation doses? BAT aims at fulfilling the same objective of protecting man and environment by identifying the best preventive measures to insure this protection. The first conclusion is therefore that even though they originate from different fields, protection of the environment on one side and radiation protection on the other, one can identify many common grounds between constrained optimisation and application of best available technique. They have the same overall objective of doing all what is reasonable to protect man and the environment. Concerning the implementation of optimisation, it is recognized by ICRP that the application of formal quantitative optimisation methods is not practical, especially in the long term. The same conclusions can be drawn for BAT since there are no precise rules on how BAT requirements can be implemented in practice in terms of both siting and design of repositories. ICPR thus emphasizes that the optimisation process relates to qualitative judgement. This explains the reason why both ICRP and IAEA associate the objective of constrained optimisation with the application of sound engineering and technical solutions as well as sound principles of quality management as detailed in ICRP 81. BAT also refers to application of sound siting and engineering as well as technical and management principles. One may foresee at this point that the implementation of both constrained optimisation and BAT would not differ significantly. They both lead to a stepwise approach where objectives for optimisation are clarified along the process. Both constrained optimisation and BAT apply throughout the site selection and design development process. BAT may thus lead to the introduction of specific requirements on the geological barriers and engineered barriers. Some difficulties may arise from the interpretation of the term best and how it can be applied for site and design selection. There is a danger that this may lead to an open-ended process and to delay decisions. ICRP and IAEA have provided pragmatic recommendations to overcome the difficulty and alleviate this potential difficulty. 15

16 3. NATIONAL REGULATION AND GUIDANCE Sweden, Finland and the United Kingdom give a large emphasis on constrained optimisation and BAT in their radioactive waste disposal regulations. The regulation for Sweden and the UK are thus presented in some detail. France also considers optimisation and BAT and some statements from the RFS III.2.f are quoted. The information on regulation of other countries involved in a geological disposal programme is derived from the INTESC study under the responsibility of IGSC. 3.1 Sweden The Swedish regulation (SSI FS 1998 and SSI FS 2005) is the most developed one on possible ways to implement constrained optimisation and best available techniques. In particular, the relative weight that should be given to either principle is also addressed SSI FS 1998 The Swedish Radiation Protection Institute has issued regulations on high level waste disposal in 1998 explicitly mentioning best available technique and optimisation. Optimisation must be performed and the best available technique shall be taken into consideration in the final management of spent nuclear fuel and nuclear waste. Best available technique is defined as the most effective measure available to limit the release of radioactive substances and the harmful effects of the releases on human health and the environment, which does not entail unreasonable costs Optimisation is defined as keeping the radiation doses to humans as low as reasonably achievable, economic and social factors taken into account SSI FS 2005 The Swedish Radiation Protection Authority s issued guidelines on the application of the regulations (SSI FS 1998:1) on spent fuel disposal in The regulations require that optimisation must be performed and that best available technique should be taken into account. Optimisation and best available technique should be applied in parallel with a view to improving the protective capability of the repository. Measures for optimisation of a repository should be evaluated on the basis of calculated risks. Application of best available technique in connection with final disposal means that the siting, design, construction, operation and closure of the repository and appurtenant system components should be carried out so as to prevent, limit and delay releases from both engineered and geological barriers as far as is reasonably possible. When striking balances between different measures, an overall assessment should be made of their impact on the protective capability of the repository. 16

17 In cases where considerable uncertainty is attached to the calculated risks, for instance, in analyses of the repository a long time after closure, or analyses made at an early stage of the development work with the repository system, greater weight should be placed on best available technique. In the event of any conflicts between application of optimisation and best available technique, priority should be given to best available technique. Experiences from recurrent risk analyses and the successive development work with the repository should be used in the application of optimisation and best available technique. Future human action: The consequences of the disturbance of the repository s protective capability should be illustrated by calculations of the doses for individuals in the most exposed group, and reported separately apart from the risk analysis for the undisturbed repository. The results should be used to illustrate conceivable countermeasures and to provide a basis for the application of best available technique. The assessment of the protective capability of the repository should instead be based on reasoning on the calculated risk together with several supplementary indicators of the protective capability of the repository such as barrier functions, radionuclide fluxes and concentrations in the environment. If the calculated risk exceeds the criterion of the regulations for individual risk or if there are other indications of substantial disruptions of the protective capability of the repository, the underlying causes of this should be reported on as well as possible measures to improve the protective capability of the repository. Summary of arguments for demonstrating compliance with the requirements of the regulations. The reporting should include an account of how the principles for optimisation and the best possible technique have been applied in the siting and design of the repository and appurtenant system components and how quality assurance has been used in the work with the repository and appurtenant risk analyses. The arguments for the protective capability of a repository should be evaluated and reported on in a systematic way. The reporting should include a logically structured argument for the protective capability of the repository with information on calculated risks, uncertainties in the calculations made and the credibility of the assumptions made. To provide a good understanding of the results of the risk analysis, it should be evident how individual scenarios contribute to the risk from the repository. 3.2 United Kingdom Environment Agency regulation The UK regulation, developed by the Environmental Agency, applies constrained optimisation and BAT using the concept of Best Practicable Environmental Option (BPEO) and Best Practical Means (BPM). 17

18 Consideration of BAT The Environmental Agency states that Best Available Techniques (BAT) are required to be considered (under EC Directive 96/61) in order to avoid or reduce emissions resulting from certain installations and to reduce the impact on the environment as a whole. Use of BAT is required when licensing the major potentially polluting industries under the IPPC legislative regime. BAT takes into account the balance between the costs and environmental benefits. Best Practicable Environmental Option (BPEO) Whilst BAT refers to installations, it may be more meaningful for certain plan makers undertaking SEA (Strategic Environmental Assessment) to consider the Best Practicable Environmental Option (BPEO). BPEO has been defined by the Royal Commission on Environmental Pollution as "the outcome of a systematic consultative and decision making procedure which emphasises the protection and conservation of the environment across land, air and water. The BPEO procedure establishes for a given set of objectives, the option that provides the most benefits or the least damage to the environment, as a whole, at acceptable cost, in the long term as well as in the short term". Best Practicable Means (BPM) (EA GRA 1997) Within a particular waste management option, the BPM is that level of management and engineering control that minimises, as far as practicable, the radiological impact of the option whilst taking account of a wider range of factors, including cost effectiveness, technological status, operational safety, and social and environmental factors. In determining whether a particular aspect of the proposal represents the BPM, the Agencies will not require the applicant to incur expenditure, whether in money, time or trouble, which is disproportionate to the benefits likely to be derived. Where it is demonstrated that BPM has been applied, doses or risks may be regarded as ALARA. Guidance on Requirements for Authorisation: GRA 1997 Principle No. 3 - Optimisation (as low as reasonably achievable) The radiological detriment to members of the public that may result from the disposal of radioactive waste shall be as low as reasonably achievable, economic and social factors being taken into account. In submissions related to the design and operation of a disposal facility, the applicant for authorisation should show that the best practicable means are being employed to ensure that the radiological detriment to members of the public, both before and after withdrawal of control over the facility, will be as low as reasonably achievable when viewed against wider perspectives, including recognition of competing claims on limited economic resources and that there is no risk-free option for managing radioactive waste. Demonstration of optimisation will entail showing that, among other things, the safety case has a sound 18

19 scientific and technical basis and that good engineering principles are being applied in facility design, construction, operation and closure. GRA 2007 An area where more detail may be required is optimisation. Optimisation is an issue at every stage of implementation, from site selection through to eventual closure of and withdrawal of control over a disposal facility. Optimisation sometimes entails options assessment and sometimes entails making the best of an option already selected. The guidance will need to describe how the environment agencies expect the developer to demonstrate that optimisation is being applied at each implementation stage liable to fall within the envisaged lifetime of the guidance. Topics that may require attention in the guidance because of the tension they may create are: optimisation for socio-economic wellbeing versus optimisation for health, safety and the environment; and optimisation for operational safety of the disposal facility versus optimisation for post-closure safety. These are potentially important topics for partnership working. The guidance needs to identify that, where changes are being considered to the design or operation of the facility for operational reasons, the effect of such changes on the post-closure safety case needs to be properly considered before the changes are implemented. 3.3 France The French Basic Safety Rule RFS III.2.f of 1991, which is presently under revision, refers both to ALARA, optimisation, BAT and the associated stepwise decision-making process. In particular, ALARA is introduced as follows: The repository design should allow keeping the level of the radiological impact as low as reasonably achievable, economic and social factors being taken into account. As for optimisation and BAT, the following quote applies: The quantitative objectives for the level of performance of the different barriers will only be able to be effectively defined after an iterative process, integrating the experience gained during the development of the repository programme. It is for this reason that a prudent approach is adopted, consisting of selecting or designing each barrier to be as efficient as is reasonably possible, taking into consideration its role in the overall safety of the repository as well as the state of knowledge, the available technology and economic factors. Thus the French rule sees perhaps optimisation as a post-hoc endeavour; BAT is the prudent approach in the absence of optimisation. 3.4 Conclusions on national regulation and guidance Best Available Techniques (not entailing excessive cost) (BAT) is a concept that is gaining ground in national regulations, with Sweden as the primary example. It is a concept already in use in other fields of environmental protection and impact assessment (the EC 19

20 integrated pollution prevention control directive can be cited as an example). BAT can be seen as a different means of optimisation. Here the optimisation is applied directly to the design and process elements, rather than based on the results of a dose or risk calculation as in constrained optimisation (ALARA). We may choose to insist on various design criteria (e.g. no loss of containment for 1000 years, a specified number of engineered barriers, restrictions on the geological setting). Unlike Sweden, Finland, U.K. and, to some extent, France, other national programmes do not seem to formally require the application of BAT but rather to show that the technologies being applied are sufficient to meet the safety and other criteria that do apply to the repository. In Sweden, requirements on the use of optimisation and BAT are a necessary supplement to a risk or dose standard. Both principles focus on the proponent s work on developing the repository system - rather than the end results of the safety calculations that should be compared with the standard. Optimisation and BAT are applicable to the whole process of developing a final repository, i.e. all steps from siting, design, construction, operation to closure of the repository. However, the application of these principles is subject to societal and economical constraints. Optimisation and BAT may be used either to supplement dose and risk criteria or, in some cases and at some time scales, to replace them. However, it is not clear how they should be interpreted in implementation and there is no consensus evident in the way different regulators use these criteria. This may originate on the fact that these concepts are not always well defined, the goals are not always the same, and there are large gaps remaining in terms of how to implement the requirements. Examining the practical experience in other fields could provide insights that might be useful to radioactive waste disposal. 4. IMPLEMENTATION OF BAT IN NATIONAL PROGRAMMES AND EXPERIENCE FEEDBACK 4.1 Application of BAT in safety cases and individual programmes As reported by the INTESC exercise initiated by RWMC in 2005, most programmes do not report the application of BAT in their safety case studies. The objective of the implementer is simply sufficiency of the chosen technologies towards meeting the applicable safety and other criteria. The focus is on demonstrating the existence of technical solutions, but not to irrevocably freeze them. As a result, and although safety is a major criterion, optimisation has not necessarily been accomplished until now. 20

21 The question is at what point should BAT be demonstrated? Decisions must be made along the way by the regulator and these decisions should be made in the framework of confidence that solutions are well founded. Regarding site selection, the question whether the best site (from the point of view of long-term safety) or a site that offers sufficient safety should be sought is still under debate in many countries. However, it may be noted that in Finland it was argued, and accepted, that the selected site (Olkiluoto) was at least as good a site as the other site alternatives studied. In Sweden, authorities accept the voluntary participation in SKB s site investigations on part of the municipalities as a societal boundary condition. Among countries developing a geological disposal programme Belgium, Canada, the Czech Republic, Germany and Switzerland do not require the application of best available technique. In Germany the proposal for the revision of the safety criteria requires that the repository has been designed in line with the state of the art in science and technology and that planning principles have been observed. In Finland, according to the General Safety Requirements (STUK-B-YTO 195, 1999) the planning shall take account the utilization of best available technology (BAT) and scientific knowledge. A part of the Environmental Impact Assessment carried out in was devoted to assessment of alternatives and in that context it was argued that geologic disposal by the KBS-3 concept (or its variant) was the best method to deal with spent fuel in Finland and Olkiluoto was at least as good a site as the other site alternatives studied. France is at the feasibility stage which focuses on the existence of technical solutions. However, as stated above, the basic safety rule RFS III.2.f considers explicitly the stepwise development of the programme and requires both optimisation and BAT. As the programme develops the implementer may thus be committed to comply with these requirements. Swedish regulation is described above. A decision whether or not the KBS-3 concept complies with the principle of best available technique has to be made after the evaluation of the application that SKB is expected to submit in In Switzerland the radiological consequences from the repository have to be reduced by appropriate measures as far as feasible and justifiable with current status of science and technology. Regarding site selection, the meaning of BAT should be further discussed. Specifically, the question whether the best site (from the point of view of long-term safety) or a site that offers sufficient safety should be sought is still under debate. A sectoral plan for geological disposal of radioactive waste has been established which objective is to set the rules and define criteria for site selection and present them to stakeholders. Safety related siting and design principles Generally, adequate siting and design are needed for ensuring safety. Some regulators accept that this is achieved by adequate design of multiple engineered barriers, or favourable site characteristics, or both, whereas others require that the principles of BAT and 21