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problematic component of their entire fuel cycle, and often also export wide ranges of chemical wastes of greater toxicity and potential environmental impact.
Many international projects have been proposed over the years, as either commercial (e.g., Pangea) or state-run (e.g., Russia) initiatives. With increasing support from the EU and the IAEA (e.g., IAEA, 2004), cooperative ventures between small countries appear to be moving forward with desk studies (see the discussion in section 7.5.3), but the difficulty of finding a suitable host country remains the main limit on progress.
At a more technical level, the way in which the safety of repository projects is assessed and presented to stakeholders is showing signs of change. The old SAs, which focussed on quantification of idealised model systems, are being replaced with ‘‘Safety Cases,’’ which present a wider range of qualitative and quantitative arguments. Such safety cases reflect a move towards greater realism and more open discussion of the limitations of the assessment. Possibly the area where this is most critical is the discussion of the ability to assess performance over very long timescales: although this has long been a concern for some programmes, in others the topic was avoided by simply defining an arbitrary time cut-off for the analysis. Simple cut-off times are increasingly questioned and this has, for example, led to considerable disruption of the US HLW project at Yucca Mountain. Even for L/ILW, however, past assumptions of repository systems being unchanged over time is seen as unacceptable, particularly for coastal facilities (e.g., Drigg, in the UK) in the light of global warming.
Finally, in terms of the design of facilities, there is also a trend towards practicality – moving away from idealised concepts which considered only post-closure performance towards those which place more weighting on constructability, operational safety, quality assurance, etc. The Japanese HLW programme is particularly advanced in this regard, but such ideas can now be seen to be gaining greater support throughout Europe and Asia. Due to a focus on ‘‘sustainability’’, indeed, there is a growing interest in project optimisation from the viewpoint of total system analysis which considers not only tangibles such as safety and cost, but also other critical factors for success such as public acceptability.
10.3. Priorities for future efforts
In Chapter 8, current (and historical) R&D priorities were described and explained but, here, following on the wave of recent changes noted in Chapters 1 and 7, it was felt appropriate to look at the more novel areas which will need to be studied in detail in the near future. Although it may be decades before operations commence in some repositories, the very high performance levels required and the consequences of potential failure are such that development and testing of many of the processes noted below need to be started immediately.
10.3.1. Waste characterisation
The point has already been made in Chapter 2 that a fully characterised waste inventory is crucial for all national programmes. Added to this is an area that has had scant attention to date (in any waste programme), namely characterisation of ‘‘unusual’’ wastes. In some national programmes this will include unusual (or unique) military
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wastes1 but, in most cases, it will include wastes from research, industry and medicine. Although much of such material is LLW, consisting of slightly contaminated rubbish or contains predominantly very short-lived isotopes, large volumes and heterogeneity give considerable characterisation problems.
Often forgotten, however, are the wastes which certainly fall into the ILW – HLW range arising from such sources – especially in programmes which explicitly focus on power reactor wastes (e.g., Japan). A major source of such waste is research reactors. In particular, in large countries there may be many such reactors (e.g., 16 in Japan) which may result in more waste than some of the smaller nuclear power programmes. Research reactors have a very wide range of designs (e.g., liquid metal cooled fast reactors, pebble beds, high temperature gas cooled, etc.) and thus result in rather exotic waste streams. Experimental fusion reactors and high-energy physics accelerators and the waste produced by these range from the mundane – fire extinguishers, fluorescent light tubes, radioactive cables etc., – to the exotic – radioactive asbestos, magnets, beam dumps (dense blocks of iron used to stop the high-energy beams). The problems here include the fact that existing wastes are generally poorly characterised (e.g., how much metal is present in a drum which was sealed up 25 years ago?) and there are many one-off items which will have to be characterised individually, meaning a large workload.
In addition, many items from such facilities are large (e.g., 20–40 tonne magnets which guide the high-energy particle beams) and will require special transportation and handling systems, again at relatively high cost due to the low number of items involved. Finally, some of the waste will prove to be highly problematic for the SA modellers – e.g., how can the release of 59Ni from a copper beam target (produced as a by-product of the high-energy particles colliding with the copper nuclei of the target) be modelled with existing codes? To the wide range of highly active and/or long-lived waste resulting from current research, medicine and industry must be added the legacy wastes from past activities. Particularly hazardous material may date back to the early twentieth century (e.g., from ‘‘radium paint’’ works, ‘‘radium needles’’ used in early radiotherapy) and may be difficult to even find due to lack of records. When such waste has been dumped, developing an inventory will be a key step in the planning of site remediation and the reconditioning of waste for disposal. This kind of problem is greatest, however, in countries where the waste resulted from military weapons development and testing though, worldwide, this problem has been little addressed to date.
10.3.2. Operational safety
Even in this book, operational safety has barely been mentioned (e.g., once each in Chapters 6 and 7), but it is slowly gaining recognition as being of as great importance to repository implementation as it is in other construction and process industries. To date, in the radwaste industry, it has been little studied in a geological disposal context and, in those few programmes where repositories are actually functioning, has been little
1 For example, the 127 Russian nuclear-powered submarines (with a total of 231 reactor cores) waiting to be dismantled in Arctic Russia (NW, 2006).
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reported2. This is strange when it is clear that a massive construction project such as a repository will certainly have safety issues not dissimilar to those of mining and underground construction. This, in itself, is daunting enough but, as this will be carried out under the close public scrutiny which is inevitably associated with anything to do with nuclear, the task seems a significant one.
Two recent, quite different, incidents clearly indicate the importance of operational safety. In the first, an accident at the Gorleben waste facility in Germany in May 1987, where a shaft liner failed, falling to the bottom of the shaft and fatally injuring a construction worker, stopped all further work until January 1989 – a full 20 months delay (see Jessberger, 1995, for details). In the second, during the preliminary phase of shaft construction at Andra’s Bure URL, a fatal accident in May, 2002 when a construction worker fell from scaffolding in the shaft caused such public uproar in France that the entire project was delayed by a year and was almost derailed completely. The important point here is that both incidents were ‘‘normal’’ construction industry accidents and had no radiation safety implications – but the public felt very insecure, nevertheless. How then would they react to an accident in a repository full of actual radwaste?
It is clear that now is the time for the radwaste industry to address this particular issue before a significant construction programme begins worldwide. As a guide, it is suggested that the following general principles and objectives (after McKinley et al., 2004) be implemented at the preliminary planning stages:
Advance planning: using a structured methodology where safety-relevant issues are identified in advance and steps are taken to avoid/mitigate the consequences
Keep it simple: minimise the number of processes, equipment and moving components
Design robustly: design for safety (e.g., ‘‘fail safe’’ equipment) and develop systems which are relatively insensitive to perturbations and/or which can be recovered/remediated in case of failure
Establish operational zoning: separate incompatible activities (e.g., ‘‘active’’ and ‘‘inactive’’ handling) by spatial and temporal zoning
Avoid degradation of key characteristics of the site: avoid presence of flammable/ explosive materials, minimise staff presence in sensitive areas, reduce time and operational activity between construction and emplacement/sealing
Idiot-proof: give special consideration to human actions and avoid these (e.g., by automating safety-critical operations) whenever possible
Implement an integrated safety and quality approach from the beginning: design procedures so that monitoring of safety is not compromised by working conditions underground, have a clear procedure for stopping/reversing operations in the case of non-conformity to specifications, etc.
None of the above processes can be described as ‘‘rocket science’’ and that may well be their weakness – namely that they are not glamorous enough to be at the forefront of planning. However, as the main objective will be to ease the quality assurance process, these principles really should be the cornerstones of the quality management philosophy of any given implementation programme. It is recommended that the international
2 Although not specifically covering repository implementation, currently the best available overview of relevance is a wide range of papers in the six-volume proceedings of the PSAM7-ESREL ’04 conference of 2004 (Spitzer et al., 2004a–f ).
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radwaste industry, perhaps prompted by international organisations such as the IAEA or WANO, need to establish and enforce a code of practice as soon as possible – and not wait for the first accidents to occur.
10.3.3. Emplacement technologies
For reasons of safety (radioprotection for HLW, SF and MOX) and ‘‘idiot-proofing’’ (for all waste forms), as many waste emplacement steps as possible should be conducted by remote control (or, more correctly, tele-handling). This is already recognised within the radwaste industry (e.g., in the SFR repository in Sweden the L/ILW packages are transported from the surface to the repository level down an inclined ramp by a remotecontrolled truck), but needs to be studied in more depth before moving to actual repository environments.
In particular, handling of HLW/SF packages will be problematic due to both the dimensions/mass of the containers and the high activity of the waste. Although the waste will be shielded to some extent by the package materials, the activity will still be too high to allow direct handling by repository staff and various means of tele-handling are currently under consideration. For example, in Fig. 5.8, a potential method for transferring a waste canister from a shielded transport flask onto a pre-formed repository transport/emplacement system is illustrated.
To date, several inactive tests of various handling/emplacement techniques have been carried out in URLs (e.g., FEBEX – see Huertas et al., 2000, for details) and have already highlighted areas where improvements can be made. Arguably, however, the real test will come when actual (active) waste canisters are used in in situ demonstration projects, as any problems that arise cannot be fixed by simply sending in engineers and a tool box.
10.3.4. Knowledge management
As has been noted elsewhere in this book, deep geological disposal of radwaste differs from most aspects of human endeavour due to the very long timescales involved and this poses certain problems that are unique to this field. The main problem is how to maintain continuity in projects which will run over several generations without, as discussed in Chapter 3, going to the extremes of developing an ‘‘atomic priesthood’’ along the lines suggested by Buser (1998). Currently, two closely linked solutions are under discussion and it is strongly recommended that both be pursued with alacrity in the immediate future.
The first is an area which is already used in other industries, but has seen little application in the radwaste industry to date, namely ‘‘knowledge management’’. If ‘‘knowledge’’ can be taken to encompass all of the science and technology (implicitly including social science, economics, medicine, etc.) which underpins a repository project3, then the term ‘‘knowledge management’’ (KM) can be assumed to cover all aspects of the development, integration, quality assurance, communication and maintenance/ archiving of knowledge – including data, information, understanding and experience.
3 As noted in JNC (2005), ‘‘It is also important to note that knowledge includes not only the ‘explicit’ information which can be rigorously documented but also the ‘tacit’ understanding and experience which exists within expert manpower.’’ This leads automatically to the second point discussed above.
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It is an active process, which is focused by specific programme or project requirements (themselves developed and structured by a requirements management system). Knowledge is not static, but evolves with time in line with the general progress in science. In addition, experience is associated directly with individual staff and accumulates with time.
In repository implementation, KM should aim to provide a common resource which is applicable to the needs of, and accessible to, all involved stakeholders. Particularly difficult is identifying gaps in knowledge and carrying out the R&D required to fill these in advance. To ensure that the required knowledge is available when the need arises, it may be necessary to complement existing requirements lists by attempts to anticipate future requirements – such planning is commonplace in the military, where think-tanks are tasked with foreseeing potential future weapons developments and recommending steps to develop countermeasures in a timely fashion.
The military are not alone in utilising the KM approach: the aerospace industry faces similar problems, where planning and developing a new aircraft may take several decades with the operational lifetime adding another couple of decades on top. Given that the number of components may lie in the millions (a Boeing 747 ‘‘Jumbo’’, for example, contains over 6 million individual parts; West et al., 2002) and that many are safety-critical, a sound KM system is obviously a must – and proves that the problem is also solvable for repository implementation.
Indeed, JAEA recently proposed (JNC, 2005) developing a system along the lines of:
a formal requirements management system (RMS)4 to guide and document the decisionmaking process
a coupled knowledge management system (KMS), to ensure that all knowledge needed to support these decisions is available as and when required
an associated system to assure quality (QMS), possibly with integrated documentation management.
To function properly, the knowledge base, and the associated KMS, should ideally have the following attributes:
Content: comprehensively covering all knowledge required by all stakeholders, which may necessitate timely initiation of work in anticipation of future requirements
Autonomic maintenance: allowing constantly expanding external databases to be utilised in a data mining process
Reliability: fully quality-assured with automatic processes to ensure the consistency of the expanding knowledge base
Active initiatives to keep both the content and the KMS structures at the state of the art
Openness and accessibility to all stakeholders, at technical levels appropriate to their needs
A robust process for ensuring the long-term conservation and archiving of knowledge of all types.
4 For any project, a hierarchy of requirements, which develop with time, can be derived directly from a project and, if this is done formally in a requirements management system (RMS), this will automatically structure the underlying knowledge base.