Specialised reactors, primarily used for research or marine propulsion, use highly enriched uranium (HEU), which contains >20% 235U, as fuel. This presents particular proliferation risks since the fuel contains weapons-usable uranium and, over the last 20 years, considerable efforts have been made to remove HEU from research reactors and to reconfigure them to use lower enriched fuel. HEU fuels typically contain lower plutonium contents than natural or LEU fuels, since they have a lower content of the 238U precursor. As well as the high fissile content, HEU fuels often have unusual compositions and structures which make them difficult to reprocess in a conventional plant.

Contamination from depleted uranium (DU) is an issue covering several sites worldwide. The properties of DU, such as its high density (19.05 gcm~3) and penetrating strength, have led to its use in a number of civil and military applications including munitions. Such munitions have been used in a number of conflicts over the past few decades with a summary provided in Table 4. Many of these rounds miss their target and can penetrate some distance into the ground.

The experimental test firing of depleted uranium munitions is also respon­sible for contamination at various firing ranges in both the UK and the USA. The UK Ministry of Defence (MOD) estimates that 15 tonnes of DU rounds were fired at an armour plate at the Eskmeals firing range in Cumbria between 1981 and 1995, with an additional 30 tonnes fired into the Solway Firth at Kirkcudbright, Scotland since 1982 (ref. 52). Experimental firing of DU rounds began in the USA at the Aberdeen and Yuma proving grounds in the early 1970s. More than 70 tonnes of DU have been deposited over 1500 acres at the Aberdeen Proving Ground, Maryland, into the sediments and the aquatic environment.53,54

Natural and depleted uranium share a similar chemotoxicity but the radio­toxicity is around 60% higher for the former. The low specific radioactivity combined with the dominance of alpha emissions means that no acute risk is associated with external exposure to DU but internal exposure presents serious health risks. Therefore, the main risk arises from DU dust generated from the impact of DU munitions on hard surfaces. Re-suspension of settled DU dust can occur if the particle size is sufficiently small. Traces of 236U and 239+240Pu have been found in DU penetrators collected in Kosovo55 and trace amounts of americium, neptunium and 99Tc are also thought to be present in DU.56

A review by the Royal Society57 estimates that in a worst case scenario for DU exposure in the battlefield, a soldier who experiences level I exposure to DU (exposure dominated by inhalation of aerosols generated by DU impact) has a increased risk of 1.2 per 1000 of death from lung cancer. However, they cite that poor data collection on battlefield exposure makes estimating such health risks very difficult. DU fragments left on the battlefield also pose a concern as a slightly increased risk of skin cancer is expected from long-term exposure to DU pene — trators. This is of particular concern for children who may be attracted to such objects. DU penetrators remaining in the ground also pose a longer term risk through potential migration to food sources or into water supplies. The mobility of the DU from the contaminated ‘‘hotspot’’ depends on a number of factors including corrosion rates, DU particle re-suspension, and proximity to surface soils and water sources. Although this form of radionuclide contamination has been the focus of much recent media interest, there is comparatively little work published on the scale of the problem, or strategies to decontaminate environ­ments contaminated by DU munitions. However, the reader is directed to a recent review on the environmental fate of DU for a more detailed critique.58

JOANNA C. RENSHAW,* STEPHANIE HANDLEY-SIDHU AND DIANA R. BROOKSHAW

ABSTRACT

The release and transport of radionuclides in the environment is a subject of great public concern. The primary sources of radionuclides in the environment are nuclear weapons testing and production, and the pro­cesses associated with the nuclear fuel cycle. Whilst nuclear weapons tests have been the main source of atmospheric contamination, resulting in global, low-level contamination, sites associated with weapon production and the nuclear fuel cycle can have localised high levels of contamination, and the spread of this contamination via aquatic pathways represents a significant environmental problem. Migration in the atmosphere will depend on the nature of the radioactive material and the prevailing meteorological conditions. Within surface water and groundwater environments, transport will be controlled by physical processes such as advection and the biogeochemical conditions in the system. In systems with significant flow, advection will be the dominant transport process, but as hydraulic conductivity decreases, chemical processes and condi­tions become increasingly important in controlling radionuclide migra­tion. Factors such as solution phase chemistry (e. g. ionic strength and ligand concentrations), Eh and the nature of mineral phases in the system have a critical effect on radionuclide speciation, controlling partitioning between solution and solid phases and hence migration. Understanding

* Corresponding author

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the complex interplay between these parameters is essential for predicting radionuclide behaviour and migration in the environment.

1 Introduction

The primary sources of radioactive contamination are the nuclear weapons and nuclear energy programmes over the past 70 years.1,2 In addition, other sources of radionuclides in the environment include the accidental release of radioactive material used in medicine and industry; the release of naturally occurring radionuclides through other industrial processes (primarily mining and mineral processing); and, more recently, the use of depleted uranium in weapons.2 In the environment, radionuclides can be transported via the atmosphere or aquatic systems, either as surface waters or through terrestrial systems in groundwater. Figure 1 summarises the main sources of radionuclides, the environmental pathways and the key processes controlling radionuclide migration. Whilst nuclear weapons tests have been the primary source of global, low-level con­tamination via the atmosphere, the other sources of radionuclides can cause localised high levels of contamination, and the spread of this contamination via aquatic pathways, and possible uptake into the food chain, represents a real environmental risk. In this chapter, the main pathways for radionuclide migration in the environment and factors controlling migration are reviewed, focusing mainly on geochemical factors controlling transport in aquatic systems.

hfMrtfKT1

Diffusion

Nuclear Weapons/Dl Munitions

Groundwater

Transport

<1 um Inorganic or organic

mol ft

Figure 1 Summary of main sources of radionuclides, the environmental pathways and the key processes controlling radionuclide migration.

The scientific framework that has evolved for the protection of humans from ionizing radiation is based on a number of related features, including the use of reference anatomical and physiological models for the assessment of radiation doses from external and internal sources; studies of radiation effects at the molecular and cellular level; a large range of experimental animal studies; plus epidemiological studies of exposed populations over many decades. Models and data have been used to derive tabulated, standardised data on the com­mitted ‘‘dose per unit intake’’ of different radionuclides for internal exposures, and ‘‘dose per unit air kerma or fluence’’ for external exposures of workers, patients and the public. Epidemiological and experimental studies have been used in the estimation of risks associated with external and internal radiation exposure. For biological effects, the data from human experience have been further supported by experimental biology. For cancer, and for heritable effects, the starting points are the results of epidemiological studies and of studies on animal and human genetics. These results are, in turn, supplemented by information from experimental studies on the mechanisms of carcinogenesis and heredity, in order to provide risk estimates at the low doses of interest in radiological protection.

In interpreting these data, certain balances have to be struck. With regard to radiation weighting factors, those for photons, electrons and muons are assigned a radiation weighting factor of 1. This is a simplification, particularly for photons, but is considered sufficient for their use in equivalent and effective dose terms because these are used for dose limitation, and assessment and control, in the low dose range. With regard to protons, external radiation sources are of most concern, and a radiation factor of 2 is used. A factor of 2 is also used for pions. These are particles of importance for exposures in aircraft, and for those involved with high-energy particle accelerators. Alpha particles are particularly important with regard to internal exposures, and a weighting value of 20 is used. A value of 20 is also used for fission fragments, which are also of importance with regard to internal exposures, and the same value is used for heavy ions, which are encountered in high altitude aviation and space exploration. Finally, neutrons are treated somewhat differently, and the radiation weighting factor for them differs in relation to energy over a range of about 2.5 to slightly over 20.

Similarly, balances have to be struck in view of the uncertainties surrounding the values of tissue weighting factors and the estimate of detriment. Thus it is currently considered appropriate, again for radiological protection purposes, to use age and sex averaged tissue weighting factors and numerical risk estimates. For stochastic effects, after exposure to radiation at low dose rates, nominal probability coefficients for detriment-adjusted cancer risk of 5.5 x 10 2 Sv [39] for the whole population and 4.1 x 10 2 Sv 1 for adult workers have been derived. For heritable effects, the detriment-adjusted nominal risk in the whole popu­lation is estimated at 0.2 x 10 2 Sv 1 and in adult workers at 0.1 x 10 2 Sv 1.

These risk estimates are called ‘‘nominal’’ by the ICRP because they relate to the exposure of a nominal population of males and females, with a typical age distribution, and are computed by averaging over age groups and both sexes. The dosimetric quantity recommended for radiological protection, the effective dose, is also computed by age and sex averaging. There are many uncertainties inherent in the definition of nominal factors to assess effective dose, but the estimates of fatality and detriment coefficients are considered adequate for radiological protection purposes. Nevertheless, as with all estimates derived from epidemiology, the nominal risk coefficients do not of course apply to specific individuals. For the estimation of the likely consequences of an expo­sure of a known individual, or of a known population, it is necessary to use specific data relating to that exposed individual or population.

In those situations in which the dose thresholds (100 mSv in a year) for deterministic effects in relevant organs could be exceeded, protective actions should be taken. At radiation doses below around 100 mSv in a year, the increase in the incidence of stochastic effects is assumed to occur with a small probability, and in proportion to the increase in radiation dose over the background dose.

In terms of managing exposure to radiation, it is also necessary to consider that, on the one hand, individuals may be simultaneously exposed to several sources, and thus an ‘‘individual-related’’ assessment of the total exposure has to be attempted; whereas, on the other hand, it is also necessary to consider all of the individuals exposed by a single radiation source or group of sources — a ‘‘source-related’’ assessment. Of the two, the primary importance, of course, is the source-related assessment, because action can be taken for a source to assure the protection of all individuals from that source.

In terms of presenting the scientific framework of radiological protection to a wider audience, the probabilistic nature of stochastic effects and the properties of the LNT model make it impossible to derive a clear distinction between ‘‘safe’’ and ‘‘dangerous’’. This inevitably creates some difficulties in explaining the control of radiation risks. The major policy implication of the LNT model is that some finite risk, however small, must be assumed, and a level of pro­tection therefore has to be established that is based upon what is deemed acceptable by society at any one time. This is the problem that the ICRP’s system of protection attempts to address.

RSC Publishing

It is often forgotten that the human species has evolved in an environment surrounded by natural sources of radioactivity. These sources are as diverse as cosmic ray particles from space, potassium-40 in igneous rocks and the radioactive decay products of radon, a gas emanating from the land beneath our feet. Indeed, for many people, the so-called ‘‘radon daughters’’ pose the largest health risk incurred by breathing air indoors. However, in the public mind, artificial radioactivity is far more important, and since the cessation of atmospheric nuclear weapon testing this is primarily the radiation associated with the nuclear fuel cycle. This has already caused major pollution issues and continues to have the potential to do so, unless handled with great compe­tence. The early years of nuclear power saw great enthusiasm for building nuclear power stations stimulated by lavish but unfulfilled promises of cheap electricity for all. This was followed by a period of disillusionment as the true costs of building nuclear power stations, generating the power and subsequent decommissioning became fully recognised, and the majority of investment went into fossil fuel sources of power. However, recent years have seen an increasing acceptance by politicians and the general public of the inevitability of damaging levels of climate change unless greenhouse gas emissions are curbed, and one of the few effective ways of doing so is through the adoption of nuclear power as a primary means of energy generation.

This volume is designed to provide an overview of some of the most important aspects of this field of science. In the first chapter, John Walls maps the technical and societal context in which nuclear power has existed since the first construction of experimental reactors. This serves to highlight many of the important issues which are taken up in later chapters, including issues such as the availability of uranium as a nuclear fuel, the consequences of fuel reprocessing, the economics of power generation and the costs of decommissioning. Other issues not explored elsewhere in depth within the volume, such as public attitudes to nuclear power, are also touched upon. The issue of nuclear fuel cycles and their by-products and consequences

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for the environment are expanded upon in the second chapter by Francis Livens, Clint Sharrad and Laurence Harwood. In particular, this chapter highlights the limitations posed by the availability of uranium as a fuel, and the advantages and disadvantages of fuel reprocessing. The latter was developed originally largely to generate plutonium for military purposes but has gained a rather poor reputation because of discharges to the environment, and most countries now plan to store rather than reprocess spent fuel.

One of the major drivers of public opinion on nuclear power is the occurrence of nuclear accidents. Some, such as Windscale, Three Mile Island and Chernobyl, are well known to all but others occurring in the former Soviet Union were kept secret from the general public, yet have generated contamination which persists to this day. In the third chapter, Jim Smith describes the causes and implications of these accidents and puts the topic into context. Both major and minor accidents and planned releases of radioactive materials have led to land contamination and have generated low-level wastes which need to be stored safely. In the fourth chapter, Jon Lloyd, Francis Livens and Rick Kimber outline the issues raised by such contamination and describe some of the consequences and the available remediation techniques. Perhaps the greatest Achilles’ heal of nuclear power generation is the fact that decommissioning of nuclear sites is required at the end of their active life, although interim ‘‘storage’’ may be used to allow cooling of the radioactivity by decay of the shorter-lived radionuclides. In Chapter 5, Anthony Banford and Richard Jarvis describe the legacy of contaminated nuclear sites and the approaches taken towards decontami­nation, and their positive and negative attributes.

The sixth chapter, by Katherine Morris, Gareth Law and Nick Bryan, deals with the geological disposal of higher activity wastes. This is currently a topical issue for many countries who have declared policies of con­structing deep geological repositories for high and intermediate level waste with a view to safe storage on a timescale of at least a million years. The many considerations which go into the siting and design of such a reposi­tory are considered in this chapter. In the seventh chapter, by Joanna Renshaw, Stephanie Handley-Sidhu and Diana Brookshaw, the pathways of radioactive substances in the environment are described. This highlights how the chemistry of the actinides and fission products determines their behaviour in the environment which, in turn, influences their mobility and ultimate potential to cause exposure of humans and other biota. Chapter 8, by Brenda Howard and Nick Beresford, describes how radioactive sub­stances translocate into biological organisms and the resultant dosimetry, and in Chapter 9, Richard (Jan) Pentreath describes the human con­sequences of exposure to environmental radioactivity. For many years, radiological protection was based upon the concept that measures adequate to protect human health would also be protective of the non-human biota. This paradigm has now shifted to one in which assessments are made of the dose to representative animals and plants and the likely consequences of those doses.

Overall, the volume provides a selective but broad overview of current issues in this long-standing but increasingly topical field, which we believe will be of immediate and lasting value, not only to practitioners in gov­ernment, consultancy and industry but also to environmentalists, policy­makers and students taking courses in environmental science, engineering and management.

After the receipt of chapters from authors but before proof correction, the Japanese tsunami caused damage to the Fukushima nuclear plant which went into partial meltdown. At the time of production of this volume this situation was continuing with very little definitive information available. Where possible, authors have included this in their chapters but it is clear that a more complete view of the incident will only emerge well after the production of this book.

Ronald E. Hester Roy M. Harrison

A modern uranium-fuelled PWR contains 400-600 tonnes of uranium in fuel, of which about a third is replaced on average each year. To support a global reactor fleet of 440, annual fuel production, at a typical enrichment of 3.5% 235U, will need to be about 8-10000 tonnes, implying uranium production of 60-70000 tonnes yr-1. Currently, about 25% of this need is being met by ‘‘blending down’’ surplus high enriched uranium from military programmes, but this will not continue over the long term.

Uranium is not a particularly rare element (crustal abundance 2.8 ppm) and in 2007, global uranium reserves were estimated at 5.5 x 106 tonnes.11 There is a "‘‘Resources’’ are the total quantity estimated to be available; ‘‘reserves’’ are that proportion of the resources which can be extracted economically. Clearly, the balance between resources and reserves varies with the uranium price. As price increases, more resources can be exploited eco­nomically and therefore become reserves. Also, a higher price prompts exploration and the identification of additional resources and reserves. Resources and reserves can also change as a result of better definition of deposits, or successful exploration. The data presented here are based on a uranium price of $130 kg-1. The uranium price in October 2010 was $138 kg-1.

comparable quantity of uranium in seawater (4.5 x 106 tonnes; mean seawater concentration 3 ppb) but it is presently difficult to envisage a cost effective, large scale process for extracting it. The current position is therefore that global reserves would provide about 100 years’ fuel at current consumption rates, but expansion even at the lower end of the scale projected will reduce this to a few decades, comparable to the lifetime of a modern reactor. However, there is a complex relationship between demand, price, exploration activity and size of reserves, so it is difficult to draw firm conclusions about the long term avail­ability of uranium.

Even so, given the very long lead times associated with nuclear technology, a debate about alternatives has to be conducted at some point over the next decades. An open uranium fuel cycle is arguably wasteful and appears not to be sustainable over more than a century or two. A closed fuel cycle, particularly if combined with fast reactors, offers a vast increase in energy availability, but at the cost of industrial scale fuel reprocessing, which is a difficult and costly technology, and the large scale creation of plutonium or other fissile materials, which brings with it major ethical and security issues. Other fission technolo­gies, such as thorium-fuelled reactors, would raise similar technical and ethical questions. Probably the most far-reaching question is therefore the role we see for nuclear fission? Is it a stopgap, lasting a few decades and bridging from a fossil fuel era to a renewable — or fusion-powered era, or is it a resource we will need to exploit over centuries? The answer to this question has substantial implications for the fuel cycle(s) we choose to develop, and the associated environmental impacts.

5 Conclusions

Nuclear fission potentially offers the prospect of very substantial amounts of energy from a low carbon source. However, all steps in the nuclear fuel cycle create wastes and have potentially major environmental impacts. The open fuel cycle creates smaller waste volumes and, at first sight wastes which are easier to manage, than a closed fuel cycle, but involves the dis­posal as waste of large quantities of potentially reusable material. The technology required for closed fuel cycles, for fast reactors, or for parti­tioning of long-lived waste components is particularly demanding and fast reactors, separations beyond Purex, and partitioning and transmutation in particular are far from mature. Likewise, many aspects of the conditioning and disposal of higher activity wastes remain challenging. In addition, the proliferation risks associated with the widespread production and use of fissile materials must be addressed. While the demand for nuclear energy appears to be growing substantially at present and is expected to do so in future, this raises complex questions for the long term, to which there are currently few clear answers.

Nuclear Fuel Cycles: Interfaces with the Environment 55

Decommissioning aims to take a plant which has been washed out at the end of operations and leave the site in its planned end state. End states could range from buildings containing waste entombed in concrete in their current location * Corresponding author

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Published by the Royal Society of Chemistry, www. rsc. org to completely clear sites available for another use. Intermediate states might include building foundations left in place while above ground structures are removed from the site.

Materials which are exported from the site must be treated to make them acceptable for final disposal. The UK presently has a near-surface, low level waste repository (LLWR) and is planning to build a Geological Disposal Facility (GDF) to contain intermediate and high level wastes. In some cir­cumstances materials will be sufficiently inactive that they are suitable for free- release and do not require disposal to one of these facilities. Disposal to one of the repositories typically requires wastes to be boxed and filled with grout, or other encapsulant. Waste boxes are stacked in the repository and then further material will be introduced to surround the boxes and provide a controlled local chemical environment. One goal of decommissioning is to minimise the amount of waste going to the GDF and LLWR.

The drivers for decommissioning are both varied and interrelated. Decom­missioning can therefore proceed for a number of reasons. These include:

• Reduction of the hazard associated with legacy radioactive inventory in ageing facilities.2

• Completion of decommissioning allows sale or reuse of the site.

• Continued existence of the site requires conformance to safety legislation and so requires care and maintenance that will incur ongoing costs that could be avoided by completion of decommissioning.

• There is a duty to future generations to avoid leaving them to clean up the waste generated by the current generation.

• To remove visual intrusion caused by large facilities.

Given that a facility is to be decommissioned, there is then a decision as to when this shall take place. The factors above will strongly influence the prioritisation of decommissioning but a number of other factors should also be considered: •

• Enhanced technology may be developed during the deferral period which improves the process.

Colloids are particles that are < 1 pm in at least one dimension, and with a high surface area, that remain suspended in the water column.135,136 Colloids con­taining radionuclides can form either through condensation of particular radionuclide species by a hydrolytic or precipitation process, degradation of nuclear waste (intrinsic colloids), or through sorption of radionuclides onto colloids of other (inorganic or organic) material, for example, iron oxyhydr — oxides or humic acids (extrinsic or carrier colloids).44,109,137

Colloidal transport of radionuclide will be affected by the geochemical and physical properties of the water system.135,138 Geochemical conditions will affect radionuclide sorption to colloids (as with sorption to mineral surfaces), colloid formation and colloid stability.44,45 For example, high ionic strength can increase colloid coagulation, causing precipitation of the colloids from the water column.139 Colloidal transport can be retarded by colloid deposition at solid — water and air-water interfaces, and by straining in pore systems, whilst shear and hydration forces can mobilise colloids.135,139 However, binding to colloids and/or the formation of colloids by radionuclides can have a significant effect on radionuclide transport, with colloid-mediated transport often being more rapid than solution phase.135,140 In studies investigating plutonium migration in groundwater at the Mayak site, Russia, plutonium was found to be both in solution and colloid-associated at distances up to 2.15 km; further afield (up to 3.9km), 70-90 mol% Pu was associated with 1-1.5nm colloids, suggesting a key role for colloid-facilitated transport to the far-field environment.141 Mori et al. (2003)142 investigated the effect of bentonite colloids on the transport of radionuclides through granodiorite at the Grimsel test site, Switzerland. In the absence of bentonite colloids, only 20-30% of the injected Am(iii) and Pu(iv) were recovered, whilst with bentonite colloids, 70-85% were recovered; in both cases transport was faster than that of dissolved species. Cs1 was found to be transported both as a colloidal fraction and in solution, with colloid-mediated transport being more rapid, but Sr21 migration was retarded by sorption to fracture surfaces and was not affected by the presence of colloids.

2 Conclusions

Radioactive contamination in the environment is mainly caused by nuclear weapons production and testing and the nuclear fuel cycle. Historically, emissions to the atmosphere have mainly arisen from weapons testing, causing low-level global contamination from the fallout. Migration in the atmosphere will depend on the nature of the radioactive material and the prevailing meteorological conditions. Within aquatic systems, both terrestrial and surface, a more significant environmental problem is caused by localised high levels of contamination from weapons production and nuclear power. Transport in such environments will be controlled by physical processes such as advection and biogeochemical conditions in the system. In systems with significant flow, advection will be the dominant transport process, but as hydraulic conductivity decreases, chemical processes and conditions become increasingly important in controlling radionuclide migration. Factors such as solution phase chemistry (e. g., ionic strength and ligand concentrations), Eh and the nature of mineral phases in the system have a critical effect on radionuclide speciation, control­ling partitioning between solution and solid phases and hence migration. Understanding the complex interplay between these parameters is essential for predicting radionuclide behaviour and migration in the environment.

Radioactive waste is created at all points in the nuclear fuel cycle: from ura­nium mining, fuel enrichment and discharges from plants, to the highly radioactive waste resulting from reprocessing spent fuel and decommissioning contaminated sites.130 The disposal of radioactive waste is one of the most difficult problems currently facing the nuclear power industry. High level waste and spent fuel disposal pose particularly acute problems given that it is the most toxic, long-lived and life-endangering wastes known to human kind.131

Earlier global planners did not consider the problem of nuclear waste until decades after nuclear power plants began operating. Perhaps oddly, the Inter­national Atomic Energy Agency did not hold its first meeting on decom­missioning and permanent waste storage until 1973 — 20 years after the first reactor was built.132 The waste problem is so technically difficult to handle and socially intractable with the public that in the past some countries got around the issue by dumping nuclear waste into the sea. France, for example, from 1967 to 1969 dumped more than 12000 cubic meters of nuclear waste from the repro­cessing plant at Marcoule into the ocean.133 The ocean dumping of low level radioactive waste began in 1946 and took place in 50 different sites in the Atlantic and Pacific oceans,134 but did not gather a great deal of disquiet until the 1970s, and was not halted until 1982 as a result of an international agreement. xlviu

From the 1970s onward, attempts were made to find a suitable way of dealing with radioactive waste — a problem highlighted in the sixth report of the UK Royal Commission on Environmental Pollution (RCEP) in 1976. One of the key recommendations to emerge from the so-called ‘‘Flowers Report’’ as it became known (after the chairman, Sir Brian Flowers) was that the UK should not embark on a programme of new nuclear power plants unless the question of waste disposal had been resolved. Waste slowly emerged as nuclear power’s ‘‘Achilles’ Heel’’.136

xlvmThe LLW was usually packaged in metal drums lined with a concrete and bitumen matrix. As one reviewer observes, ‘‘So far, samples of sea water, sediments, and deep sea organisms collected on the various sites have not shown any excess in the levels of radionuclides above those due to nuclear weapons fallout, except on certain occasions where caesium and plutonium were detected at higher levels in samples taken close to packages at the dumping site’’.135

Across a number of countries the failed attempt to find a site for the geological storage of nuclear waste initiated a period of reflection on the part of the nuclear industry and its governmental backers. As a result, a newer, tentative and more open governance style was proposed whereby the formerly closed, secretive decision-making process was opened up. Previously excluded stakeholders were drawn into the process with mixed results. This required a culture change within organisations and a search for inclusive democratic processes that could enable debate to occur between previously antagonistic groups.137,138 It was clear that without a solution for the long-term disposal of high level legacy wastes no new nuclear stations could be contemplated, a position reflected in many countries policy statements on nuclear energy.

Taking the UK as an example, after the rejection of a proposal to build a rock laboratory at Sellafield in order to test whether a geological disposal site would be geologically appropriate, the nuclear industry and government undertook a period of reflection that produced the Managing Radioactive Waste Safely (MRWS) process launched in 2001, which recognised that the closed decision-making process in the past had failed and sought a new open way forward based on stakeholder dialogue and deliberation.

As part of this ‘‘new transparency”, a new committee, the Committee on Radioactive Waste Management CoRWM was ushered into existence in 2003 and was composed of people from scientific, technical and social scientific backgrounds. The committee was novel in its plural composition and its ambition to integrate scientific analysis with public and stakeholder engage­ment (PSE). CoRWM was to inspire public trust in decision making, which had suffered not only because of the failures in nuclear waste policy, but also due to previous incidents such as the BSE crisis.139,140 The committee operated for three years, in which time it undertook the most ambitious public and stakeholder engagement process ever seen in the UK to date. In its final report in July 2006, one of the recommendations was to move forward with deep geological disposal of nuclear waste, but simultaneously called for an accompanying robust programme of research on interim storage and further R & D on deep geological storage.141 These findings mirror those of compre­hensive analyses published elsewhere which suggest that the science under­pinning long-term geological isolation is sound and that the deep geological storage of high level waste is the most appropriate option.142 Cost estimates for such a facility vary widely with a median figure of £12 billion. Whilst the majority of stakeholders supported the recommendations, a number of sta­keholders (such as Greenpeace) and devolved administrations (Scotland) rejected them in favour of above ground interim storage. A recent report develops the criticisms of CoRWM recommendations.143

The CoRWM process illustrated what can be achieved when previously antagonistic stakeholders work collectively on a common problem, with suffi­cient time, resources and good will. xlix Whilst a move toward greater openness

xlix The experience of working on previous stakeholder dialogue projects which began during the mid-1990s in the nuclear arena has persuaded people within and outside of the nuclear industry of the possibility and potential of this form of collaborative working.

and engagement became evident in relation to finding a solution to long-term nuclear waste in a number of countries,144 the picture in relation to pressing forward with new nuclear build is less reassuring. Contemporary policy dis­course with its emphasis upon securitisation, in this case, energy security, reintroduced a policy making style redolent of early nuclear policy making. As Blowers observes, ‘‘the style of governance is less inclusive and participative’’, in many ways reverting back to some of the characteristics of what Dryzek describes as the ‘‘actively exclusive state’’ that had been prevalent in the UK until the early 1990s.145 Whilst the government consultation during 2007 on new nuclear stations emphasised public participation, it was beset by a host of problems that led to it being successfully challenged in the courts by Green­peace UK. The judge in a damming verdict stated that the consultation was ‘‘seriously flawed’’ and “manifestly inadequate and unfair’’ given that insuffi­cient and ‘‘misleading’’ information had been made available by the govern­ment for consultees to make an “intelligent response”.14б, l

Similarly in France, the ‘‘Bataille Law’’ of 1991 on radioactive waste man­agement marked a step towards a more democratic decision-making process, designed to put an end to the ‘‘cult of secrecy’’ that had hitherto prevailed in nuclear policy questions, but also to facilitate the exploration of different policy options.148 European legislation on transparency and citizen participation also pushed the French nuclear establishment towards more openness. Whilst this new processes of consultation and discussion was beset by a number of problems, researchers have analysed the new arenas where experts and the public come together as revealing the limits of traditional representative democracy, suggesting the need to press forward with this emerging form of ‘‘technical democracy’’149 which, its been suggested, can increase public confidence and trust in the technical and organizational effectiveness of waste management and disposal.150

Although the cost of finding a solution to nuclear waste is eye watering, this is dwarfed by the price tag attached to the decommissioning of nuclear plants. Unlike a coal-fired power station, for example, a nuclear power plant cannot just be dismantled and the site used for other purposes. A complex process is initiated where radioactive parts, buildings and, on occasion, contaminated land must be carefully dismantled, treated and stored as nuclear waste. None of which is cheap. It is estimated that the final bill for decommissioning the UK’s current fleet of nuclear plants will be in excess of £100 billion.151 Much of the cost is attributable to the clean up of the oldest civilian and military plants.152 Until recently, most cost estimates of nuclear plants excluded decommissioning costs, which can equal or exceed construction costs.153 As a result the UK government is suggesting a levy will be imposed on electricity produced from [The Blair administration began openly flagging new nuclear stations as a solution to climate change from 2006 onwards, despite CoRWM’s clear statement that its conclusions should not be taken as either green or red light to new build; the alleged ‘‘solution’’ to the waste issue provided by CoRWM was used by the government in its arguments in favour of new build. This suggests that government can selectively and strategically deploy more open and transparent forms of decision making.147 nuclear plants to cover decommissioning and other back end costs, although there are concerns that this levy will not be sufficient.

For years the nuclear industry deferred decommissioning until as far as possible into the future. Even an official report published as late as 1995 sug­gested operators of nuclear plants in the UK could defer decommissioning for 100 years.154 It was not until the decommissioning of the Berkeley Magnox reactors had to be planned after they stopped operating in 1988 and 1999 that the problem of how to pay for decommissioning came to light. l‘ In coming to power in 1997 the New Labour administration began the process of searching for cost effective solutions to the decommissioning challenge, drawing on the experience of the US decommissioning effort in particular, which was based on contracting out decommissioning to private sector consortia. Rather than sell nuclear liabilities the government has “contractorised” them. As a result of the involvement of the private sector in more accurately capturing the true cost of decommissioning, liabilities increased by 16% alone in 2007.156 The hope is that the skills and experience of the private sector will lead to the use of innovative solutions thereby driving down costs and reducing the final bill to the taxpayer. This has yet to be proven.

For most countries the preferred approach is to dispose of nuclear waste in facilities built in rock formations hundreds of meters below the earth. To date only Finland is in the process of building such an underground disposal facility, with Sweden only having recently come to an agreement with a local com­munity as to where the facility will be built. On the other hand the country with the most nuclear waste, the USA, has just rejected a disposal site after inves­tigating it for 20 years. For campaigners this seriously impacts upon the jus­tification to expand the new build programme. For scientific and political reasons the Yucca Mountain site in Nevada, part of the Nevada nuclear test site, was chosen to store the nation’s radioactive waste (a decision ratified by Congress) after a period of intensive research and debate in which $3 billion was spent. It was set to open in 2010 but opposition by environmental groups and Nevada politicians have kept things on hold. The Obama administration cancelled the plans after coming to power. The USA now has nowhere to place the 70 000 tonnes of waste currently being stored on-site at nuclear power plants and other facilities scattered throughout the country.157

Insofar as the four accidents can be categorised, there is a clear dividing line between the circumstances leading to the early accidents at military facilities (Kyshtym and Windscale) and the later civilian nuclear power plant accidents (TMI and Chernobyl). In his review of Windscale and Kyshtym, Jones2 iden­tified the common factors in these accidents:

‘‘…both occurred at installations whose main purpose was to produce plutonium for their respective national weapons programmes, at a time when pressures to produce the necessary material quickly were extreme; moreover in both cases the processes involved were imperfectly understood and would not be considered safe by modern standards’’.

All four were failures both of equipment and management/operation of that equipment, but the latter two could both have been prevented had the opera­tors taken the appropriate actions in the build up to and during the accidents. In fact, at both TMI and Chernobyl, it appears that the operators’ actions, largely through no fault of their own, contributed significantly to the accident. An important contributing factor to the design and management failures leading to the TMI accident, identified by the President’s Commission,27 was an attitude that nuclear power plants were inherently safe; an attitude which also prevailed in the Soviet Union prior to Chernobyl. The President’s Commission on TMI concluded that:

“The Commission is convinced that this attitude must be changed to one that says nuclear power is by its very nature potentially dangerous, and, there­fore, one must continually question whether the safeguards already in place are sufficient to prevent major accidents’’.

“We are convinced that if the only problems were equipment problems, this Presidential Commission would never have been created. The equipment was sufficiently good that, except for human failures, the major accident at Three Mile Island would have been a minor incident. But, wherever we looked, we found problems with the human beings who operate the plant, with the management that runs the key organization, and with the agency that is charged with assuring the safety of nuclear power plants’’.27

Since both TMI and Chernobyl, major improvements have been made in power plant design and in the safety culture of the nuclear industry. But the recent accident at the Fukushima Daiichi nuclear power plant serves as a reminder that extreme events can and do happen. The nuclear industry and regulators must not allow the belief to take hold that major accidents are impossible. It was a major earthquake and Tsunami which caused the Fukushima accident, but a human planning failure player a important part.

In terms of environmental and human health impacts, it is obvious that releases of radioactive materials at Kyshtym and Chernobyl had major impacts on the human population both in terms of enhanced cancer risk and, impor­tantly, the social, psychological and economic impacts of permanent evacuation. Though many radiation-induced cancers, even from the Chernobyl accident, are never likely to be epidemiologically distinguishable from ‘‘natural’’ background cancers, it is possible to estimate the cancer effects from estimates of collective dose. Indicative estimates of collective doses from the four accidents is given in Table 4, though this comparison is far from comprehensive, partly because of the difficulty in estimating doses, and partly because different approaches were used in the different studies. Despite these limitations, it is clear the collective doses from Chernobyl were by far the most significant. It is important to note, however, that the influence of atmospheric nuclear weapons testing on the collective dose to the World population was much greater than that for Chernobyl. All of these collective doses are dwarfed by the much greater collective doses to the World population from natural and medical sources of radiation.

The damage to the ecosystem caused by these accidents was severe in small areas where organisms were exposed to extremely high doses in the period fol­lowing the releases. However, long-term environmental damage from chronic,

lower level, radiation is less clear. Evidence of long-term damage to organisms (at a genetic, individual or population level) from these studies is often contra­dictory, partly as a result of poor study design and methods in some studies, but also because of the confounding from other environmental and ecological vari­ables. At both Chernobyl and Kyshtym, the evacuated areas have, in the long term after the accident, been described by some as a ‘‘nature reserve’’ since the damage human influence has on ecosystems has been removed.