The site selection process for the UK GDF(s) is outlined in the MRWS White Paper.1 The process is based upon community volunteerism, which is coupled to published geological sub-surface screening criteria (SSSC) that provide an initial assessment of the geological suitability for hosting a GDF. Furthermore, underpinning the volunteerism approach is the principle of “participation

without commitment”; here, host communities taking part in the GDF siting process can exercise a right of withdrawal up to the point where GDF under­ground observation and construction activities are due to begin. Currently, the UK government has extended an invitation to communities to submit expres­sions of interest in hosting the UK GDF. As of autumn 2010, two communities in west Cumbria have entered non-committal negotiations with the government and this process is ongoing. As part of this development, the British Geological Survey have been asked to apply the SSSC to the potential host communities, thus indentifying sites with unsuitable geology at an early stage.1 The primary exclusion criteria are the presence of: (i) fossil fuel deposits; (ii) major areas of sub-surface waste or gas storage; (iii) potable water aquifers; (iv) extensive shallow (<500 m) permeable formations; or (v) complex hydrogeological environments (deep karstic formations or known source rocks for thermal springs).1 If potential sites pass the SSSC, the host communities can then submit a formal ‘‘decision to participate” in the siting process. Thereafter, the site(s) will be subject to increased levels of scrutiny. This will initially involve desk based studies, and if appropriate, sub-surface investigations, until a decision can be made regarding the final host location. Importantly, the out­come of this process means that there can be no assumption that the GDF will be built in ‘‘ideal’’ geology; instead, the GDF host geology will depend upon the geological setting of the participating communities.

Benchmarks, or some form of usually numeric criteria, allow the outputs of environmental assessments to be placed into context and aid decisions on the need for further assessment or regulatory/remedial action. Historically, the derivation of radiological benchmarks for environmental assessment has relied upon expert judgement.

A benchmark relates to a protection goal which, in contrast to humans, is usually considered to be at the population level even though the data under­pinning the benchmark relates to individuals. It can be legally binding criteria or a standard linked to a regulation where exceeding the values may result in legal or regulatory action. Alternatively, a benchmark can be a conservatively derived screening value, which aims to screen out sites where there is no cause for concern and identify those where further consideration is needed. The latter are frequently linked to tiered risk assessment schemes and serve primarily as a trigger for further investigation. Screening values in radiological assessments are often referred to as the Predicted No Effect Dose Rate (PNEDR). The methods used to derive PNEDRs are outlined in the following section; these approaches are often consistent with those used in the risk assessment of chemicals. Currently, there is no agreement on what to do if refined assessments estimate dose rates in excess of screening benchmarks.

Purex (Plutonium URanium EXtraction) separation has been the predominant process used for industrial scale nuclear fuel reprocessing in France and the United Kingdom, two countries which have devoted much effort to closing the civil nuclear fuel cycle. In principle, Purex chemistry is based on solvent

extraction and is straightforward. The irradiated fuel is dissolved in HNO3 and the oxidation states of uranium and plutonium are controlled to vi and iv, respectively. The fuel solution is contacted with tri-n-butyl phosphate in an inert solvent, such as kerosene, and the uranium and plutonium are extracted into the solvent phase, leaving almost all fission products in the aqueous phase, which forms the high level liquid waste stream. The plutonium is then separated by reduction to oxidation state iii and stripped into dilute HNO3. Finally a uranium stream is separated by back extraction into dilute HNO3.

Contaminants are treated by electrokinetic remediation through the applica­tion of a low intensity electric current between a cathode and an anode placed within the contaminated soil. Through this process, organic, inorganic and radioactive contaminants can be separated and extracted from clay-rich soils, sludges and sediments. Application of the electric field creates an acidic front around the anode, due to an excess of H1 ions, and an alkaline front at the cathode, due to an excess of OH~ ions. The electric gradient created initiates the movement of water, charged chemicals and charged particles through the processes of electro-osmosis, electromigration and electrophoresis, respectively, moving anions towards the positive electrode and cations towards the negative. The contaminants can then be removed through electroplating or precipitation at the electrodes, the use of ion exchange resins or pumping the waste to the surface.99 Complexing agents, surfactants and other reagents can be used to increase the efficiency of treatment.100

A paper by Lageman examines the processes involved in electrokinetic remediation and examines numerous sites where inorganic and organic con­taminants have been treated through this technique.101 Work by Cundy examines the use of electrokinetics to generate a Ferric Iron Remediation and Stabilisation (FIRS) barrier. By applying a low, direct electric potential between two or more sacrificial Fe-rich electrodes placed in the contaminated soil, a strong pH/Eh gradient can be generated in the soil column. This forces the precipitation of an Fe-rich barrier between the electrodes.102 Soil samples were taken from the Ravenglass estuary, Cumbria, UK, containing artificial radionuclides from the nearby Sellafield plant and placed into a Perspex cell. Cast iron electrodes were embedded into the soil and a potential of 1.5 V was applied between them for 17 days. After this time, a 30% reduction in 60Co was observed in the anode zone with a 50% enrichment in the iron band. Man­ganese, calcium and strontium were also depleted in the anode zone and enriched on, or around, the iron band. Arsenic, which was desorbed at the high pH found in the cathode zone, was found to be 100% enriched in the iron band. The radionuclides, plutonium and americium, were not found to be sig­nificantly mobilised over the this time frame.102 The use of electrodes as a potential electron donor for microorganisms resulted in the removal of U(VI) from solution in a study by Gregory and Lovley. When the electrodes were poised at -500 mV in the absence of microorganisms, U(vi) was removed from solution but was returned to solution when the poise at the electrodes was removed. If Geobacter sulfurreducens was present on the electrode, then U(vi) did not return to solution suggesting the uranium was reduced from U(vi) to

U(iv).103 A review on the electrical stimulation of microbes is provided by Thrash and Coates.104

Electrokinetic remediation offers advantages as a treatment method through: the ability to treat both inorganic and organic contaminants at the same time; being able to treat contaminants in areas of low hydraulic flow by inducing movement of water, ions and colloids through an electric field; and competitive cost and effectiveness. However, the process can be ineffective when target ions are in much lower concentrations than non-target ions, and corrosion of the anodes in acidic conditions presents in situ treatment problems.

The behaviour and mobility of any radionuclide depends on its chemical spe — ciation,60 which will control properties such as solubility and reactivity with respect to surfaces.15 Chemical speciation is critically dependent on the bio­geochemical conditions; factors such as pH, Eh, the presence of complexants and the nature of mineral surfaces present in the system, and the interplay between these factors, will all affect the partitioning of radionuclides between the solid and solution phases.15,61,62 Figure 3 illustrates the key geochemical processes controlling radionuclide speciation and some of the factors affecting these processes. Processes such as sorption and (co-)precipitation may retard radionuclide migration, whilst dissolution, complexation and colloid formation may enhance migration by retaining the radionuclide in the solution phase.

Waters in the environment have varying biogeochemical signatures. Surface waters can be subdivided into fresh water and saline environments, with areas of mixing (brackish or estuarine zones). Within the fresh water environments, rivers and streams are likely to be of neutral pH, low ionic strength and oxi­dizing conditions. In such systems, within significant flow, advection (transport

of a solute due to the overall water flow) is the dominant transport process. However, as hydraulic conductivity of the system decreases, such as in ground water systems, advection has less impact on solute migration,63 and chemical gradient-driven processes and diffusion processes become increasingly more important.64 Within lakes and reservoirs or estuarine environments, mixing can be limited and zones of different pH and Eh conditions can develop.43,65 In such environments, regions of more reducing conditions can promote retardation processes, such as microbial reduction of redox-sensitive radionuclides, which can limit radionuclide migration. In the subsurface, radionuclides are trans­ported as solutes by groundwater flow, but the prevailing biogeochemical conditions will significantly affect migration. Groundwater environments are typically reducing due to the low oxygen penetration in such zones.

The principal doses received by workers are associated with exposure to X-rays and gamma rays together with, but to a lesser extent, beta particles and neutrons. Doses at the body surface are usually estimated by the use of personal dosimeters, but assessments are also made in relation to internal exposures where relevant. Measurements are usually made to ensure compliance with legal or adminis­trative dose limits. Workers employed by the nuclear industries are involved in many different aspects of the nuclear fuel cycle; fuel fabrication; reactor opera­tion; the care, maintenance and decommissioning of reactors; and the restoration of nuclear sites. A variety of other workers may be exposed to radiation sources in the course of their work, as well as those involved in military defence and its associated industries, and those in nuclear medicine and radiography.

Annual dose rates received by nuclear workers are typically of a few mSv or less. What is of particular interest, however, is their long term collective dose, and how this relates to their general health, and particularly to the incidence of cancer amongst them. Several studies have been made, the most recent being that conducted by the Health Protection Agency.20 This study involved the data from some 174 500 workers from pre-1976 (back to the end of the Second World War) up to 2001. About 68% of them had a lifetime dose of 10mSv or less, about 20% had a lifetime dose of 10 to 50 mSv, 6% lifetime doses up to 100 mSv, and the remaining 6% lifetime doses in excess of 100 mSv.

The results of the study showed that, as in previous analyses, total mortality and mortality from major causes were less than expected from rates for England and Wales. This ‘‘healthy worker effect’’ remains even after adjust­ment for social class. The only cause for which mortality was statistically significantly greater than that expected from national rates was pleural cancer, and this probably reflected exposure to asbestos.

Mortality and incidence from both leukaemia (excluding chronic lymphatic leukaemia), and the grouping of all malignant neoplasms other than leukaemia, increased to a statistically significant extent with increasing external radiation dose. The corresponding central estimates of the trend in risk with dose were similar to those for the survivors of the atomic bombings of Hiroshima and Nagasaki. And whilst there was some evidence of an increasing trend with dose in mortality from all circulatory diseases combined, the irregular pattern in risk with dose and similarities with the corresponding pattern for lung cancer suggest that this finding may, at least in part, be due to confounding by smoking. In contrast, both for mortality and incidence, the trend with dose in the risk of all malignant neoplasms (other than leukaemia) would not appear to be an artifact due to smoking, because the relationship remanis the same if the data for lung and pleural cancer (which are related to smoking) are excluded.

In the 21st century several factors have combined to revive the prospects for nuclear power. First is the realisation of the scale of projected increased demand for electricity worldwide, but particularly in rapidly developing countries, for which nuclear is increasingly seen as part of the solution. Secondly, there is a raised awareness of the importance of energy security and thirdly, the urgent need to encourage low carbon energy generation technolo­gies to mitigate the threat of dangerous climate change. Over the last decade the increasing arguments for nuclear and the pace of new orders for nuclear reactors has led talk of a ‘‘nuclear renaissance’’.64 At the turn of the millennium the nuclear industry and its supporters recognised that a more proactive approach was necessary to ensure public acceptance, as well as the need to promote nuclear as an attractive option for policymakers. Books such as Preparing the Ground for Renewal of Nuclear Power65 reflected the growing confidence of the nuclear industry.66 A confidence which increased with the public support of prominent environmentalists, ‘‘nuclear power is the only green solution’’,67,xxx and, moreover, that ‘‘the worst possible nuclear disasters are not as bad as the worst climate change disasters’’.68 A raft of government sponsored studies such as Options for a Low Carbon Future reinforced the march of nuclear, viewing nuclear as a potential weapon in the struggle to reduce carbon emissions in the battle against climate change. One prominent report argued that:

“The present study has confirmed the Royal Commission on Environmental Pollution (RCEP) conclusion that the replacement of the current nuclear power stations by new nuclear stations and an expansion of nuclear power could help the UK reduce its CO2 emissions by 60% or more by 2050’’.69

The attractiveness of nuclear power then, as the Intergovernmental Panel on Climate Change (IPCC) suggests, is because ‘‘the life cycle GHG emissions per kWh from nuclear power plants are two orders of magnitude lower than fossil-fuelled electricity generation and comparable to most renewables’’.70

If we are to shift from a reliance on coal and gas which are the dominant sources of electricity across the globe, what are we to use? Demand reduction in the form of energy conservation can play an important role here but we are still left with replacing supplies from fossil fuels. xxxl

France is often held up as an example of what can be achieved in terms of emissions reductions when nuclear power forms a large part of the [27] [28] electricity supply, for it generates 75% of its electricity from nuclear power and emits 6.6 tonnes of CO2 per capita, compared with 10.4 tonnes per capita for Germany.71 A recent report from the MIT on the Future of Nuclear suggests that nuclear-generating capacity be increased almost three­fold, to 1000 billion Watts by 2050, thereby avoiding 1.8 billion tonnes of carbon emissions annually from coal plants (about 25% of the increment in carbon emissions otherwise expected in a business-as-usual scenario).72,xxx11 From a strict climate change perspective, nuclear power is an improvement over conventional coal-burning power plants. A nuclear power plant does not directly produce greenhouse gas emissions (unless it is running idle, being refuelled or operating on backup generators) and it emits about one-tenth to one-twentieth the carbon dioxide emissions over the course of its lifecycle as compared with a comparatively sized conventional, fossil — fuelled power plant.74,75 Still, reprocessing and enriching uranium requires a substantial amount of electricity, often generated from fossil fuel-fired power plants, and uranium milling, mining, plant construction and decommissioning all generate greenhouse gas. A recent review which assessed the most cost effective low carbon base load electricity-generating technology concluded that ‘‘nuclear energy is the cheapest option and best able to meet the IPCC timetable for GHG abatement’’.76 Whilst there would be large financial costs involved in any new nuclear programme, proponents argue that all of these potential costs are insignificant compared with the risks posed by climate change.77

As a result of these debates we have witnessed a change in the nature of the public discourse around nuclear power over the past decade. Those factors which previously led people to reject nuclear power (such as costs, waste dis­posal, accidents, proliferation concerns, etc.) are being discounted because of the way in which nuclear power has been reframed and repackaged as a solution to climate change, energy security78 and as a means of meeting the increasing demand for electricity in developing countries.79 All of which is reflected in the more positive public attitudes toward nuclear power that are shown in opinion polls.

Surveys conducted in the UK in 2005 (ref. 80) and 2006 (YouGov), found that 35% and 40% of the respondents, respectively, were in favour of new nuclear. This rose to 62% and 68% if nuclear new build was coupled with a concerted policy of promoting renewables.81 The latest opinion poll in the UK shows the highest level of public support for nuclear power in over a decade, with 40% of people favourable to nuclear (up seven points from 2009), while 17% are unfavourable (down three points).82 In 2008, 43% of Finns supported new nuclear build, while 25% wanted to phase out [29] nuclear.83 Public support as monitored by the Eurobarometer polls suggests that in 8 out of 25 countries of the EU there is a majority in favour of nuclear power.[30] However this increase in optimism and support for nuclear power has been negatively impacted by the Disaster that occurred at the Fukushima nuclear power plant in Japan during March 2011. (As the author received proofs for this paper the devastating Tsunami hit Japan on March 11th 2011, thereby setting in train a sequence of events that led to the catastrophic loss of coolant in a number of nuclear reactors at the Fukushima Daichi nuclear plant, on the west coast of Japan, leading to contamination of the site and surrounding area. The disaster has now been classified as a 7 on the severity scale for nuclear accidents, the same as Chernobyl.) Whilst the medium and longer term impacts on public per­ceptions of nuclear energy are unknown, the immediate response has been stark. In the week following the disaster a Gallup poll found that ‘‘support for nuclear energy worldwide has fallen from 57 percent before Japan’s nuclear disaster to 49 percent now, but supporters still outnumber oppo­nents’’. However there are large regional and country differences. In America for example a recent poll found that 44% of the public were in favour and 47% opposed to ‘‘the construction of nuclear power plants in the United States’’,167 this is down from a high of 62% from just a year earlier.168

Within the EU a recent poll found that whilst the Fukushima nuclear disaster has led to greater worry across the European Union about the safety of nuclear power plants, with the exception of Germany — citizens were broadly confident about the management of nuclear plants in their own country. Indeed, ‘‘66% of Germans now oppose nuclear power, while just 19 per cent support it. The French are evenly split on the matter, at 36 per cent each, while the British are in favour by a margin of 35 per cent to 30 per cent’’.169

Worldwide there are 60 new nuclear plants under construction with 131 more proposed, a number of which are in countries which do not have nuclear power e. g. United Arab Emirates, Bangladesh, Vietnam, Egypt, Indonesia, Thailand and Turkey (Montgomery 2010).[31] The global recession has dented the hopes of some countries who have decided not to press ahead with further nuclear expansion after initial investment, e. g. Turkey.[32] The new build programme in Europe (excluding Russia)[33] amounts to just six reactors in four countries: Finland, France, Romania and Slovakia. The new build programme in Europe began in 2004 when the first of the late third-generation units was ordered for Finland — a 1600 MWe European PWR (EPR). A similar unit is being built in Flamenville, France, with another on order as part of the replacement for the PWRs built in France during the 1970s and 1980s. There are plans for a new build programme in a number of countries such as the UK, Bulgaria, Czech Republic and Slovenia. Prior to the Fukushima disaster there were countries (such as Italy and Sweden)xxx™ who were considering the revival of mothballed nuclear programmes. Even in what has become a staunchly anti nuclear country such as Germany, who only a decade ago pledged a “comprehensive and irreversible” end to nuclear power, had pledged to extend the life of its existing reactors by an average of 12 years. Nuclear power is to act as a bridge in order to allow renewable energy to eventually provide most of the country’s energy needs by 2050 (up from 16% today). From this perspective, nuclear buys time for renewable energy to fully develop and mature, ‘‘while slowing down the worst effects of global warming’’.86

However as a result of the Fukushima disaster a number of countries have imposed some limits to prolonging the operating life of existing nuclear plants and/or placing limits on future new build proposals. Germany for example, one of the most anti-nuclear countries in Europe, has imposed a 3-month mor­atorium on the reactor lifespan extension passed in 2010. Moreover, Germany has also decided to temporarily shut down 7 of its 17 reactors, with Italy imposing a one year moratorium on the construction of new nuclear power plants. A number of other countries have tasked their regulatory authorities to investigate the disaster in order to learn lessons that can be applied to increasing the safety of domestic nuclear plants (UK, USA and France) with a small number content to proceed with new build proposals such as Slovakia with China announcing a pared back nuclear expansion programme. A recent report issued by UBS suggests that at the very least around 30 nuclear plants may have to close as a result of Fukushima, in particular those in seismic zones or close to national boundaries.170

Plans in Europe and North America are overshadowed, however, by those in China, India, Japan and South Korea. The centre of gravity in building new nuclear plants has shifted toward Asia87 and to China in particular. China alone plans a six-fold increase in nuclear power capacity by 2020, and has more than one hundred further large units proposed and backed by political deter­mination and popular support. A large portion of these are the latest western design, expedited by modular construction. One can say that the history of nuclear power starts with science in Europe, blossoms in UK and USA with the latter’s technological might, languishes for a few decades, then has a new growth spurt in East Asia. China and India, with nearly half the world’s population and determined policies to increase electricity and decrease poverty, have led the way in new build. China has 17 third-generation reactors under construction with 124 planned or proposed.

Recently it has become official policy in China to transform nuclear energy development from ‘‘active’’ to ‘‘aggressive’’.88 The economic boom has ensured that there are sufficient funds to cover the capital costs of building nuclear plants, with preferential tax policies available for the companies involved.89 The large sums of money that the three state owned companies are looking to invest ($117 billion in the case of the Chinese National Nuclear Corporation alone) has meant that at least one of them is looking to launch an initial public offering (IPO) in order to raise funds on the international markets. The move to build new nuclear plants was inspired in part by the experiences of 2002, when ‘‘blackouts rolled in and factory lights flickered; the grid sucked dry by a decade of breakneck industrialization. Oil and natural gas were running low’’.90

China’s electricity consumption quadrupled between 1980 and 2000. The cumulative impact of air pollution as a result of burning fossil fuels is estimated to kill 750000 people a year and economic loss is put at 6% of GDP.91 Moreover, around 30% of China is polluted by acid rain due to the large amounts of sulfur dioxide produced by coal-fired power stations,92 with three coal-fired stations coming online each week in China.94,xxxviu A recent study by BP suggests that ‘‘China can only continue at current rates of production for 38 years before its coal reserves are exhausted. That compares with 245 years in the USA and 105 years in India’’.95

In order to try and mitigate the problems of energy security, environmental pollution and climate change, China is seeking to acquire security of supply from a variety of sources, recognising that coal will remain the dominant source of energy, with nuclear only supplementing this. The transport of coal is major headache as the coal reserves are mainly located in the north or northwest, with nearly half the country’s rail capacity being used to transport coal.96

This situation contrasts with that of the USA, the leader in the first wave of nuclear energy production, where there have been 17 applications to the Nuclear Regulatory Commission (NRC) for joint construction and operating

mvmChina has approximately 25 000 coal mines employing 3.4 million people. Observers have suggested of the decline in availability of coal after 2020 that ‘‘no fossil fuel other than coal will be able to provide sufficient energy to sustain current economic growth rates in the years ahead, and non-fossil sources will require unprecedented and perhaps unachievable levels of investment just to make up for declines in coal production — never mind providing enough to fuel continued annual energy growth of seven to ten percent per year’’.93

licences for about 25 new nuclear power reactors. However, these plans seem rather ambitious given the recent announcements from key private sector partners in the new build programme that they have withdrawn due to pro­jected overruns in project costs. Only one reactor is actually being built, at Watts Bar in Tennessee.

In fact one of the main obstacles to an ambitious new build programme in North America and Europe is the cost of financing nuclear plants. This consideration over finance has led to private sector contractors pulling out of proposals in America, to states such as Bulgaria unable to find companies willing to invest in nuclear plants at proposed rates to the reactors being built in France and Finland which are over time and cost. The response has been for governments to implement direct or indirect subsidies to facilitate investment which has drawn criticism from civil society groups and other energy providers. There are also concerns over the price and availability of uranium to power nuclear plants, and in shortages of skilled labour and reactor vessels. In what follows, we explore a number of the barriers to the future of the nuclear renaissance and the implications for nuclear power in the transition to a low carbon energy system.

1.2 Events Leading to the Accident

The explosion, on the 29th of September 1957, of a high-level waste tank at the Mayak plutonium production and reprocessing facility in Siberia was, until Chernobyl, the World’s most severe nuclear accident. Since the Mayak site and associated town Ozyorsk were secret and as such were not found on Soviet maps, the accident was named after the next nearest town of Kyshtym. The first official acknowledgement of the accident by the Soviet Union was in June 1989 (ref. 15). The stored wastes had been treated to remove radiocaesium, but contained various other fission products. The concrete storage tank had a volume of 300 m3 and contained, at the time of the explosion, 70-80 tonnes of liquid waste.16 The cause of the accident was the failure of the tank’s cooling system, which caused the waste to heat up. The high temperature and the evaporation of water from the tank resulted in a chemical explosion of nitrate and acetate compounds in the waste. It is believed that all of the 740 PBq of waste was released from the tank, 90% of which remained within the site, the remaining 10% being dispersed to the environment in a plume of aerosols which reached a height of one kilometre,16 as illustrated in Figure 2.

Radioactive wastes comprise materials that are contaminated by, or incorporate, radioactivity above threshold levels defined in UK legislation, and for which there is no further economic use. It is important to note that the UK radioactive waste legacy is complex and varied because of the diverse history of power reactors and nuclear weapons development. The HAWs destined for geodisposal in the UK are identified as items that: (i) cannot be managed under the policy for the long term management and storage of solid low level radioactive waste in the United Kingdom, and (ii) are not managed under the Scottish Executive’s emerging policy for radioactive waste.1 These HAWs are broadly categorised depending on their radioactive content as either heat-generating high level waste (HLW), or non heat-generating intermediate level waste (ILW). In addition to HLW and ILW, some small volume items of low level waste (LLW), a range of materials that are currently not declared as waste such as spent fuels and stockpiles of uranium and plutonium, and any wastes from any new nuclear reactors, may be managed via geodisposal. Each waste type is described in detail in sections 2.1-2.4.

Radionuclides can be transferred to plants via stomatal uptake and cuticular absorption, often referred to as ‘‘foliar uptake’’. For many radionuclides, however, ‘‘root uptake’’ is more important than foliar uptake, although the
latter can be significant for some radionuclides if there is a continuous aerial discharge. After foliar or root uptake, radionuclides are translocated via the phloem to different parts of plants.

The processes in soil described above lead to variation in plant uptake due to the differing proportions of radionuclides available in the soil solution. For example, the transfer of radiocaesium from soil to many plants follows the order: clay <loam < sand < organic soils, but there is considerable variation within, and overlap between, the four soil groups. Plant uptake of americium is generally ten-fold higher than that of plutonium.26

The uptake of radionuclides by plants (fungi and microbes) also varies between different species, as well as with the soil type.