- •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
62 |
I.G. McKinley et al. |
is still an order of magnitude higher than typical costs for geological disposal. In particular due to the risks of explosion during takeoff, any protection system would have to be extremely robust – which would increase costs considerably. This is unthinkable for the thousands of tonnes of spent fuel produced each year and hence presumes an efficient (and expensive) reprocessing programme to concentrate the most ‘‘problematic’’ isotopes and immobilise them for disposal. In addition, a space programme to dispose of all problematic waste from the global nuclear power industry would certainly also have significant environmental detriments from the effects of the launches themselves.
Paper studies of future space transportation systems have considered more exotic alternatives to rockets, such as rail-gun launchers and space elevators (e.g., Cosman, 1985). Apart from requirements for major advances in materials technology, such novel concepts must inevitably be associated with high costs and risks of catastrophic failure. In theory, at least, a space elevator combined with an electro-magnetic rail-gun could provide an option for firing waste packages beyond earth’s orbit. Further speculation involves so many assumptions about ‘‘possible’’ future developments that it falls into the realms of science fiction rather than technical analysis. As such, space disposal is no longer a serious option for any national programme (see also comments in Dutton et al., 2004).
3.4.3.3. Icesheets and permafrost
This is another option which has a certain amount of popular appeal due to the images of remote ‘‘frozen deserts’’ – including icecaps, glaciers and permafrost (Fig. 3.8). These have been studied for a long time (e.g., Philberth, 1959; Schneider and Platt, 1974) and, indeed, permafrost disposal has been implemented for some waste types and can, if deep enough, be considered a variant of geological disposal (section 3.3.2). Due to the high transport and handling costs, study of this option generally focuses on higher activity wastes. Such heat-emitting wastes would be ‘‘self-sinking’’ in ice, eventually ending up on the bedrock under the icecap if not actually anchored from the surface (Fig. 3.9).
As noted in section 3.4.2, this option is excluded by the Antarctic Treaty, leaving only sites in Greenland and certain Canadian and Russian islands as alternative options. As the basis of such disposal is the permanence of the icesheet over timescales of interest, these are now seen as less credible due to concerns raised by global warming. Massive retreat of ‘‘permanent’’ continental icesheets and melting of permafrost over the last decades make predictions of future behaviour completely impossible on the basis of existing climatic models – which have such ranges of uncertainty that even complete melting of the Antarctic icesheet over coming centuries cannot be precluded. It seems unlikely that any technological development within the near future will reduce such uncertainties to the point that a credible safety case could be produced. They are thus not presently considered to be credible for implementation in any national programme, despite a recent patent for such a concept (Valfells, 2002).
3.4.4. Non-options; long-term surface storage
There is often a grey area between storage and disposal – as even disposal sites may be actively controlled and monitored (often termed ‘‘institutional control’’) for a time period long enough for activity to decay to some ‘‘negligible’’ level (typically several hundred
Development of geological disposal concepts |
63 |
Fig. 3.9. Placing waste below icecaps. The heat from the waste package should melt the ice, allowing the packages to ‘‘self-sink’’ to the bedrock below if not anchored from the surface.
years). Storage here is taken to mean holding waste in a facility that is not only controlled and monitored but is also fully inspectable and the waste is easily retrievable at any time. For both disposal with institutional control and storage, a particular concern is the longevity of the institutions charged with this work. Such institutional stability is, however, much more critical for storage as, in effect, there are no other safety barriers of the type included in a disposal facility. Also, after institutional control, a disposal site can, in principle, be abandoned. After storage, the waste still needs to be disposed of and, though its radiological hazard should then be negligible, it still may need to be treated as chemotoxic waste.
In either case, the IAEA (IAEA, 1992, 2002, 2003) feels that true institutional control is only realistic for wastes dominated by short-lived isotopes and, given the volatility of human history over the last century, achieving confidence in the longevity of institutions (and funding) for such periods is particularly difficult for most countries (see also the discussion in Nagra, 1997, on societal stability versus geological stability). Nevertheless, storage variants over ‘‘indefinite’’ time periods have also been seriously proposed for long-lived waste. Strange as it seems, this is not without precedent – e.g., the chemotoxic waste depot at Teuftal (Canton Berne) is specified to require supervision for ‘‘as long as Switzerland remains a populated country’’ (Nagra, 1997). Similarly, contaminated sites in the USA may simply be set aside for restricted access ‘‘indefinitely.’’