- •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
41
Development of geological disposal concepts
Ian G. McKinleya, W. Russell Alexanderb, Petra C. Blaserc
aDepartment of Environmental Engineering and Architecture, Graduate School of Environmental Sciences, Nagoya University, Japan bBedrock Geosciences, Auenstein, Switzerland
cPetraconsult, Uetikon a.S., Switzerland
3.1. Introduction
In this chapter, the development of geological disposal concepts is examined in some detail, beginning with an introduction to the historical evolution of disposal of radioactive wastes (section 3.2), and a consideration of the range of options available. As indicated in Fig. 3.1, many different possibilities exist for the relatively small volumes involved, but this book focuses on those classed as geological disposal. The general international consensus of this being the best approach is explained in terms of the fundamental properties of the geological environments currently under consideration to host repositories (section 3.3), which includes illustrations of repository design evolution using examples from Sweden and Switzerland.
To put this in perspective, however, a short overview is given on the alternatives to geological disposal (section 3.4), which are classed as politically blocked options such as sub-seabed disposal (section 3.4.1), technically impractical options such as partitioning and transmutation (P&T) (section 3.4.2) and ‘‘non-options’’ such as long-term storage (section 3.4.3). Section 3.5 looks into alternatives to ‘‘conventional’’ mined repositories which are the current focus of most national programmes. Although quite novel, such options are receiving increasing attention as more national programmes move towards repository implementation and begin to realise the potential shortcomings in many of the conventional designs. Finally, the chapter concludes with section 3.6, which considers the prospects for future developments in this area.
3.2. Historical evolution of geological disposal concepts
All materials are naturally radioactive to some extent and so are all wastes. Wastes with enhanced levels of naturally occurring radionuclides have been produced by mining and industrial activities since prehistoric times, but significant quantities of wastes with
DEEP GEOLOGICAL DISPOSAL OF RADIOACTIVE WASTE |
2007 Elsevier Ltd. |
VOLUME 9 ISSN 1569-4860/DOI 10.1016/S1569-4860(06)09003-6 |
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Fig. 3.1. Radioactive waste management options.
radiologically meaningful activities of radionuclides began to arise only at the end of the nineteenth century. Despite the widespread interest in radioactivity following its discovery, there was no particular concern about wastes and, indeed, many applications of radionuclides in the early part of the twentieth century focussed on their assumed benefits to health. Identification of ‘‘radioactive waste’’ as a special category is related to the dramatic increase in the production of such material associated with the early nuclear weapons programmes and the subsequent growth of nuclear power. Nevertheless, ‘‘legacy wastes’’ requiring special handling are continually discovered from abandoned facilities which predate this period (e.g., factories which produced or used luminous ‘‘radium’’ paint).
The development of waste management options in the early days is best documented for the US, although the situation in the other nuclear powers of the time (the UK, USSR and France) was certainly similar. In the early days, atomic energy (as it was then called) was part of the military programme of the US and the first plants were, for security reasons, established in isolated places with few inhabitants so little heed was taken of waste problems (Fig. 3.2). As A.E.Gorman noted ‘‘. . . as problems of waste disposal arose they were not too difficult to take care of because of this isolation’’ (Gorman, 1955).
Most waste disposal was, in any case, rather basic. A 1952 USAEC-sponsored survey of radwaste producers found that ‘‘. . . about 41% of the users disposed of radioactive wastes by dilution and discharge into sewers. Although this may not be a hazardous procedure at present (owing to the limited quantities of isotopes currently in use), the procedure is not a wise one and should be discouraged’’ (Miller et al., 1954).
Development of geological disposal concepts |
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Fig. 3.2. Until 1970, solid low-level and transuranic waste at the Atomic Energy Commission’s nuclear weapons facilities (shown here is Hanford Reservation, circa 1950s) ‘‘was frequently disposed of in cardboard boxes. Once filled, this unlined trench would have been covered with dirt, leaving the cardboard to deteriorate . . .’’ (US Dept. of Energy, http://www.ocrwm.doe.gov/).
As the nuclear power industry began to develop after the second world war, it was accepted that such an approach could not continue and, in 1955, the USAEC signed a contract with the NRC to set up the Committee on Disposal of Radioactive Waste on Land, specifically to look into the problem with the aim of ‘‘Evaluating all suggestions and research to date on disposal methods that involve land surface or underground sites . . .’’ (NRC, 1957). A very early focus was on disposal in salt bodies (see section 3.3) and other deep rock formations and this approach has continued to the present day.
Nevertheless, it was also recognised at an early stage that there were a range of variants of this option and, indeed, possible alternatives to geological disposal on land (e.g., USAEC, 1974; Schneider and Platt, 1974). The latter studies were carried out in a fairly comprehensive manner and often form the basis for reviews of alternatives to national geological disposal concepts which seem to re-appear in the literature on a 5–10 year repeat cycle (recent examples being SKB, 2000; Nirex, 2002; Dutton et al., 2004; CoRWM, 2005). It is often forgotten, however, that socio-political and technical boundary conditions were very different three decades ago and hence the pros and cons of different options are now weighted in a very different manner.
A good illustration of this is provided by D&D (dilute and disperse) options which were extensively studied – and implemented – in particular association with nuclear weapons programmes (e.g., Fig. 3.3). It may seem incredible today that direct disposal (dumping) of MegaCuries (PBq-EBq) of radioactive waste into aquifers, rivers, lakes and seas was considered acceptable practice. This occurred, however, at a time when
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100-D
100-N
100-KE,KW
100-B,C Reactor
Areas
Central Plateau
200-East
200-West Area Area
0 2 4 6 8 10 kilometers
0 1 2 3 4 5 miles
Tritium (MCL 20,000 pCi/L)
90 Strontium (8 pCi/L)
Uranium (20 g/L)
99 Technetium (900 pCi/L)
129 lodine (1 pCi/L)
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Richland
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Fig. 3.3. Plumes of radionuclides in the groundwaters of the Hanford Reservation, mainly resulting from radionuclides disposed of into ‘‘soak-away’’ trenches.
atmospheric nuclear weapons tests were a significant source of both local and global radiation doses and when the Cold War threat of nuclear war made hazards associated with radwaste seem rather trivial by comparison. Although D&D should not be discounted out of hand as an important part of waste management strategies (it remains, in effect, standard practice for the disposal of many low-toxicity radioactive noble gases released during reactor operation or SF reprocessing and for the disposal of many chemotoxic wastes), it is clear that the previous cavalier approach to waste dumping would not be acceptable now and should not be considered in the future.
Here, it is valuable to overview the wide range of design options which could be considered for management of radioactive wastes (Fig. 3.1). This helps to clearly identify the justification for not considering particular options, so that they could be revisited should there be a change in critical boundary conditions. However, it is also important to allow the reasonable questions of the general public and other interested stakeholders to be answered (see also Chapter 9) – as such alternatives are always brought forward in general debates on geological disposal.