- •Preface
- •Acronyms
- •Introduction
- •Background and objectives
- •Content, format and presentation
- •Radioactive waste management in context
- •Waste sources and classification
- •Introduction
- •Radioactive waste
- •Waste classification
- •Origins of radioactive waste
- •Nuclear fuel cycle
- •Mining
- •Fuel production
- •Reactor operation
- •Reprocessing
- •Reactor decommissioning
- •Medicine, industry and research
- •Medicine
- •Industry
- •Research
- •Military wastes
- •Conditioning of radioactive wastes
- •Treatment
- •Compaction
- •Incineration
- •Conditioning
- •Cementation
- •Bituminisation
- •Resin
- •Vitrification
- •Spent fuel
- •Process qualification/product quality
- •Volumes of waste
- •Inventories
- •Inventory types
- •Types of data recorded
- •Radiological data
- •Chemical data
- •Physical data
- •Secondary data
- •Radionuclides occurring in the nuclear fuel cycle
- •Simplifying the number of waste types
- •Radionuclide inventory priorities
- •Material priorities
- •Inventory evolution
- •Assumptions
- •Errors
- •Uncertainties
- •Conclusions
- •Acknowledgements
- •References
- •Development of geological disposal concepts
- •Introduction
- •Historical evolution of geological disposal concepts
- •Geological disposal
- •Definitions and comparison with near-surface disposal
- •Development of geological disposal concepts
- •Roles of the geosphere in disposal options
- •Physical stability
- •Hydrogeology
- •Geochemistry
- •Overview
- •Alternatives to geological disposal
- •Introduction
- •Politically blocked options: sub-seabed and Antarctic icecap disposal
- •Sea dumping and sub-seabed disposal
- •Antarctic icesheet disposal
- •Technically impractical options; partitioning and transmutation, space disposal and icesheet disposal
- •Partitioning and Transmutation
- •Space disposal
- •Icesheets and permafrost
- •Non-options; long-term surface storage
- •Alternatives to conventional repositories
- •Introduction
- •Alternative geological disposal concepts
- •Utilising existing underground facilities
- •Extended storage options (CARE)
- •Injection into deep aquifers and caverns
- •Deep boreholes
- •Rock melting
- •The international option: technical aspects
- •Alternative concepts: fitting the management option to future boundary conditions
- •Conclusions
- •References
- •Site selection and characterisation
- •Introduction
- •Prescriptive/geologically led
- •Sophisticated/advocacy led
- •Pragmatic/technically led
- •Centralised/geologically led
- •Conclusions to be drawn
- •Lessons to be learned (see Table 4.2)
- •Site characterisation
- •Can we define the natural environment sufficiently thoroughly?
- •Sedimentary environments
- •Hydrogeology
- •The regional hydrogeological model
- •More local hydrogeological model(s)
- •Crystalline rock environments
- •Lithology and structure
- •Hydrogeology
- •Hydrogeochemistry
- •Any geological environment
- •References
- •Repository design
- •Introduction: general framework of the design process
- •Identification of design requirements/constraints
- •Concept development
- •Major components of the disposal system and safety functions
- •A structured approach for concept development
- •Detailed design/specifications of subsystems
- •Near-field processes and design issues
- •Design approach and methodologies
- •Design confirmation and demonstration
- •Interaction with PA/SA
- •Demonstration and QA
- •Repository management
- •Future perspectives
- •References
- •Assessment of the safety and performance of a radioactive waste repository
- •Introduction
- •The role of SA and the safety case in decision-making
- •SA tasks
- •System description
- •Identification of scenarios and cases for analysis
- •Consequence analysis
- •Timescales for evaluation
- •Constructing and presenting a safety case
- •References
- •Repository implementation
- •Legal and regulatory framework; organisational structures
- •Waste management strategies
- •The need for a clear policy and strategy
- •Timetables vary widely
- •Activities in development of a geological repository
- •Concept development
- •Siting
- •Repository design
- •Licensing
- •Construction
- •Operation
- •Monitoring
- •Research and development
- •The staging process
- •Attributes of adaptive staging
- •The decision-making process
- •Status of geological disposal programmes
- •Overview
- •Status of geological disposal projects in selected countries
- •International repositories
- •Costs and financing
- •Cost estimates
- •Financing
- •Conclusions
- •Acknowledgements
- •References
- •Research and development infrastructure
- •Introduction: Management of research and development
- •Drivers for research and development
- •Organisation of R&D
- •R&D in specialised (nuclear) facilities
- •Introduction
- •Inventory
- •Release of radionuclides from waste forms
- •Solubility and sorption
- •Waste form dissolution
- •Colloids
- •Organic degradation products
- •Gas generation
- •Conventional R&D
- •Engineered barriers
- •Corrosion
- •Buffer and backfill materials
- •Container fabrication
- •Natural barriers
- •Geochemistry and groundwater flow
- •Gas transport and two-phase flow
- •Biosphere
- •Radionuclide concentration and dispersion in the biosphere
- •Climate change
- •Landscape change
- •Underground rock laboratories
- •URLs in sediments
- •Nature’s laboratories: studies of the natural environment
- •General
- •Corrosion
- •Cement
- •Clay materials
- •Degradation of organic materials
- •Glass corrosion
- •Radionuclide migration
- •Model and database development
- •Conclusions
- •References
- •Building confidence in the safe disposal of radioactive waste
- •Growing nuclear concerns
- •Communication systems in waste management programmes
- •The Swiss programme
- •The Japanese programme
- •Examples of communication styles in other countries
- •Finland
- •Sweden
- •France
- •United Kingdom
- •Comparisons between communication styles in Finland, France, Sweden and the United Kingdom
- •Lessons for the future
- •What is the way forward?
- •Acknowledgements
- •References
- •A look to the future
- •Introduction
- •Current trends in repository programmes
- •Priorities for future efforts
- •Waste characterisation
- •Operational safety
- •Emplacement technologies
- •Knowledge management
- •Alternative designs and optimisation processes
- •Materials technology
- •Novel construction/immobilisation materials: the example of low pH cement
- •Future SA code development
- •Implications for environmental protection: disposal of other wastes
- •Conclusions
- •References
- •Index
77
Site selection and characterisation
Tim McEwen
McEwen Consulting, Melton Mowbray, England, UK
4.1. Introduction
Radioactive waste can remain a hazard for a considerable time and repositories need to be found where such waste can be disposed of safely. To ensure that radioactive waste is managed in an appropriate manner, a suitable process needs to be followed to select any radioactive waste disposal site. Such a process needs to be both transparent and defensible, so that the community where a site is eventually located has confidence that it was selected properly.
The selection of sites for the disposal of long-lived radioactive waste is often the most contentious part of a disposal programme and the selection process can be very timeconsuming. There are several examples throughout the world where site selection programmes have had to be abandoned and only a few examples where the process of selection of deep disposal sites has proceeded in a relatively smooth manner and where a site has been selected for repository construction. The best example of a success story is
¨ ¨
that of the situation in Finland (McEwen and Aikas, 2000).
There is a variety of strategies that can be applied in selecting disposal sites. A previous review of such options is provided in Savage (1995), which is itself partly a summary of work presented in an earlier report to SKB by McEwen and Balch (1993). There have been further developments in site selection strategies since these reviews, to take account of the more inclusive approach that is now generally followed in making decisions regarding sensitive siting issues, with the result that there is now a greater emphasis on volunteerism in site selection and more interaction with the public and other stakeholders during the siting process (see also the discussions in Chapters 7 and 9).
Generally, the process of site selection can be defined in terms of two key factors: first, the extent to which an overtly rational, rather than a pragmatic, approach is adopted and, second, the extent to which satisfactory technical solutions are imposed rather than advocated and accepted by recipient communities. Another broad distinction can be made between geologically led and advocacy led approaches. In this context, geologically led means that the primary determinants in defining areas of search are related to geological and hydrogeological characteristics of the sites. In contrast, an
DEEP GEOLOGICAL DISPOSAL OF RADIOACTIVE WASTE |
2007 Elsevier Ltd. |
VOLUME 9 ISSN 1569-4860/DOI 10.1016/S1569-4860(06)09004-8 |
All rights reserved. |
78 |
T. McEwen |
advocacy led approach seeks to identify volunteer communities and, at this point, geological considerations would be taken into account to exclude those considered incapable of satisfying long-term safety criteria. Geologically led and advocacy led approaches can be combined; this is the approach being followed by NUMO in Japan, in that factors that would exclude an area from consideration (known as Evaluation Factors for Qualification), such as active faulting or volcanic activity, together with ‘‘favourable factors’’, have been published and municipalities that might be interested in volunteering are provided with this information (NUMO, 2002). These exclusion factors are incorporated into the Japanese legislation on the disposal of radioactive waste, whereas the favourable factors are not required by the legislation but need to be considered when selecting Preliminary Investigation Areas (PIAs). A similar approach, with the use of ‘‘geoscientific exclusion criteria’’ which define specific minimum requirements for a host geological environment, together with favourable geological factors that need to be considered to compare and contrast potential areas and to select those most promising, has been recommended by AkEnd for a future site selection programme in Germany (AkEnd, 2002). Socio-economic and planning criteria would also be taken into account during this analysis, with a ‘‘citizens’ forum’’ representing the local community being a central element in this process.
It is beneficial for any such criteria or guidelines applied at this stage of a site selection programme to be relatively simple, as for many areas or sites little is likely to be known about their geology and hydrogeology, except in the broadest terms. It is also likely to be counterproductive at this stage to set prescriptive criteria, with a few notable exceptions, and to make the selection process too formal, as this will result in a programme that will be rigid and unresponsive to change. Exceptions to this recommended lack of rigid criteria are provided by countries that have dynamic geological environments, e.g., Japan, where the existence of active faults, and the USA, where current igneous activity, provide obvious constraints on the location of a future repository1.
Table 4.1 illustrates the range of approaches that are possible in a site selection programme and where they have been followed. It is not possible to pigeonhole all site selection programmes within this simple four-part categorisation, as some of them would appear to straddle the categories listed. It is also unlikely that a current or future site selection programme in a country with a democratic government would follow the pragmatic/technical approach, as this has been shown to be unsuccessful in the past, mainly because of the lack of any proper consultation with the public or, in fact, the majority of the stakeholders that would be affected by the development of the proposed repository. Similarly, the centralised/geological approach that has been successfully applied in the past in France, at least for the disposal of LLW, is also unlikely to be applied in the future. This is because it relies on a high level of public acceptance of nuclear power, combined with a centralised government. There are countries, such as Finland, where the use of nuclear power is generally accepted; however, the approach adopted in Finland to site selection has been consensual, with a high level of both local and national public support for the development of a repository at Olkiluoto, where a new reactor is also being constructed.
1 AKEnd had some very detailed technical exclusion criteria which were rather surprising in context (e.g., criteria on hydraulic gradients would completely eliminate the potential HLW host formation in Switzerland, the Opalinus Clay).
Site selection and characterisation |
79 |
The strategy followed in any particular country may lie anywhere between these broad categories of strategies, which represent end-members of a continuous spectrum of possibilities. Examples are provided in Table 4.1 to illustrate the range of approaches that have been, or are currently being, followed and the extent to which they have been successful.
4.1.1. Prescriptive/geologically led
The USA possesses a well developed legislative framework for the assessment of potential repository sites. The open, decentralised style of government is also coupled with easy access to judicial review of the decision-making process. This environment encouraged the development during the 1980s of a sophisticated, if rather mechanistic and prescriptive, site selection methodology for a HLW disposal site, the aim of which was to meet objections head on in a rational and demonstrably equitable manner. The later stages of the site selection programme used Multi-attribute Utility Analysis (MUA; see also MAA or MADA), described by Merkhoffer and Keeney (1987), Keeney (1987) and Keeney and von Winterfeldt (1994), that led to the stepwise identification of three possible sites. MUA (Keeney and Raiffa, 1976) is a technique recommended by the ICRP for use in optimisation problems (ICRP, 1989).
The approach followed in the USA was, in fact, geologically led in that assumptions were made initially as to the most appropriate geological formations. The next stage was to define rigorous repository performance measures in terms of a range of health and safety, environmental, socio-economic and economic impacts and then to compare relative aggregate performance. In particular, the process was designed to make explicit assumptions, judgements, preferences and trade-offs in a systematic manner. The design of the selection process and the legislation that accompanied it made the selection programme complex and legalistic, in marked contrast to the situation in Sweden and Finland.
Having selected three potential sites (Hanford, Deaf Smith County and Yucca Mountain), site characterisation programmes were started at these sites. The final choice of Yucca Mountain was, however, political and this site was selected mainly because the State of Nevada had less political power in Congress than did the states of Texas and Washington (and perhaps, because of the proximity of the site to the Nevada Test Site, little opposition was expected). The original plan was also to develop a second repository for HLW in the eastern part of the USA but, due to political pressure, this programme was shelved before it had reached the stage of selecting a shortlist of potential sites (see also comments in Chapter 10).
4.1.2. Sophisticated/advocacy led
This approach has become more common over the last decade or two as problems with the use of other approaches to site selection have become apparent. The essential element of this approach that distinguishes it from others is substantial public participation in the selection process, which may include the use of volunteer sites – depending on the specific structure of the site selection programme, areas or sites are able to volunteer either during the early stages of the programme or later as the programme proceeds. A key characteristic is an emphasis on providing mechanisms for community
Table 4.1
Examples of the different approaches to site characterisation
Category |
Characteristics of environment |
Characteristics of methodology |
Examples |
||
|
|
|
|
||
Prescriptive/ |
Open government, easy access to |
Sophisticated, mechanistic site selection process, with |
Multi-attribute methodology adopted in USA |
||
geological |
|
judicial review of site selection process |
|
emphasis on procedural objectivity and considerations of |
(e.g., Merkhoffer and Keeney, 1987). |
|
Centralised decision-making |
|
wider socio-economic and environmental factors |
Similar, in part, to later stage of Nirex ILW |
|
|
|
Detailed technocratic legislative |
Initial site selection process governed by technical/ |
site selection programme (UK) |
|
|
|
|
|||
|
|
framework |
|
geological/hydrogeological criteria |
|
|
Sceptical public |
Public acceptance exercises engaged late in the day and |
|
||
|
|
|
|
focused at local level |
|
|
|
|
Siting imposed |
|
|
Sophisticated/ |
Open government |
Early consultation over whole of potential siting area |
Nagra siting programme (L/ILW – Nagra, |
||
advocacy |
|
Decentralised decision-making |
|
Sophisticated, objective site selection process and |
1983a,b, HLW – Nagra, 1994, 2002b) |
|
|
||||
|
Possibly sceptical public (at least |
|
consideration of wider socio-economic and environmental |
Co-operative Siting Process (Canada) |
|
|
|
initially) |
|
factors |
(SPTF, 1987; STF, 1990). |
|
|
|
Initial site selection process governed by degree of public |
Posiva siting programme (Finland) |
|
|
|
|
|
support |
¨ |
|
|
|
|
(McEwen and Aikas,¨ 2000) |
|
|
|
|
Siting voluntary/responsive |
SKB Siting Programme (Sweden) |
|
|
|
|
|
|
(e.g., Milnes, 2002). |
|
|
|
|
|
NUMO siting programme (Japan) |
|
|
|
|
|
(NUMO, 2002, 2004). |
Pragmatic/ |
Centralised government; little access to |
Initial site selection process geologically and |
Early stage of Nirex ILW site selection |
||
technical |
|
judicial review of selection process |
|
hydrogeologically led |
programme |
|
Sceptical public |
Public acceptance exercises engaged late in the day and |
|
||
|
Weak legislative control of selection |
|
focused at local level |
|
|
|
|
process |
Little emphasis on socio-economic considerations |
|
|
Centralised/ |
Centralised government |
Siting imposed |
Situation in France pre-Bataille |
||
geological |
High level of public acceptance of |
Site selection geologically and hydrogeologically led |
(e.g., Bataille, 1991, 1993) |
||
|
|
nuclear power (generation) |
Intensive local advocacy following the selection |
|
80
McEwen .T
Site selection and characterisation |
81 |
involvement and an exchange of information on risks and benefits at the earliest stage of the selection process. Another feature is that the costs to the local community are often explicitly recognised, either in being able to carry out their own independent analysis of the investigations or the proposed development of a repository (as has been the case in Sweden), or in making provision for compensation if a repository is developed (as is the situation in Switzerland and France). Examples of this volunteer approach are provided by the site selection programmes in Sweden (Milnes, 2002), Finland (McEwen and
¨ ¨
Aikas, 2000) and Japan (NUMO, 2002), with a somewhat different approach being followed in France, where a site has been selected not for a repository, but for a URL (e.g., Bataille, 1993), as part of a research programme on the management of radioactive waste (see also details on a variety of approaches in Chapter 9). Generally, it is agreed with the local community that no radioactive wastes can be disposed of in such a URL although, if the geological environment proves suitable for radioactive waste disposal, there is the possibility of selecting a nearby location, or a similar geological environment
¨ ¨
elsewhere, as a potential repository site (cf. the situation in SKB’s URL in Aspo in Sweden). A recent recommendation from AkEnd (AkEnd, 2002) regarding a future site selection programme in Germany also comes to the same conclusions regarding the desirability, or actually the necessity, of public participation at all stages. AkEnd introduced the concept of ‘‘willingness to participate’’, rather than volunteerism, to refer to the process of public involvement in selecting sites for investigation and possibility later for underground exploration.
Nagra in Switzerland began an extended process around three decades ago. For L/ILW, a set of 100 sites was originally selected based on predominantly geological considerations. MAA, using both geological and socio-economic criteria, was used to narrow this down to 20 and then three sites (note that the entire process was documented in openly available Nagra technical reports). A fourth site was added following a government recommendation (a late volunteer site that was, in fact, one of the original 100). Following detailed site characterisation at all four sites, Wellenberg was selected based on an extensive MAA, including a full SA and detailed logistical analyses. The selection procedure was widely publicised (e.g., Nagra, 1983a,b) and selection of the site was accepted by the government and regulatory authorities, only to be finally excluded in a local referendum. For HLW, siting focused on geological stability criteria due to a regulatory requirement to show safety ‘‘for all time’’ (HSK, 1993). Exclusion criteria eliminated much of the country, leaving only a band of possible host rocks, including both sediments and crystalline basement, in the north of the country. Stepwise, regional characterisation was initiated – first sequentially, then with sediment and crystalline host rock options running in parallel. As the aim was only to show the ‘‘feasibility of finding a site’’ (rather than actually defining a site, as in the L/ILW case), a decision was taken to focus on the sedimentary option (in particular, the Opalinus Clay) due to reasons of explorability.
SKB in Sweden started its site selection programme in the early 1990s, following research over the previous fifteen years at six ‘‘study sites’’, at other drilling sites and in two URLs (Milnes, 2002). This research allowed for the development of a country-wide feasibility study (SKB, 1995), covering geological and other aspects relevant to the disposal of spent fuel. However, this study drew considerable information from another study which had been carried out on the geology of Sweden for more general purposes (Fre´den, 1994). This was followed by feasibility studies in eight municipalities over a