Select Committee on Science and Technology Third Report


PART C: OTHER WASTE MANAGEMENT ISSUES

CHAPTER 7: REPROCESSING, PLUTONIUM AND MOX

BACKGROUND

7.1 The United Kingdom faces complex challenges in nuclear waste management because of the variety and volume of wastes that must be dealt with. These wastes have resulted from the active role that the United Kingdom has played (and continues to play) in both civil and military developments since the Second World War. The United Kingdom has operated numerous different commercial and research reactor types (including submarine reactors), has had an active fuel reprocessing programme for military and commercial purposes since the 1950s, is a world leader in nuclear materials research and the application of nuclear materials for medical purposes, and operates facilities for fuel fabrication. The various programmes to clean up wastes from previous activities also generate their own waste, albeit in more manageable forms. Each operation often generates its own waste stream which may require a unique management solution because of the physical nature of the waste, or its chemistry, or its activity. The waste management task for the United Kingdom is thus comparable to that of the US, France, or the former Soviet Union, rather than to nations such as Sweden, Canada, the Netherlands and others which have only operated a limited number of different reactor types and have no nuclear weapons programme.

7.2 In this chapter we look at some of the issues for the United Kingdom which feed into the debate on longer-term solutions to nuclear waste. These include plutonium and its uses and the reprocessing of spent fuel. A description of the issues is given under each heading and this is followed by a review of what our witnesses told us. Our opinions are summarised at the end of the chapter.

REPROCESSING

7.3 Whether a country reprocesses spent fuel or not is a key factor in determining what types and volumes of waste have to be managed. This, in turn, may have a bearing on the long-term management strategy that can be used. Compared to a "once-through" fuel cycle, reprocessing reduces the volume of HLW, but increases the volume of ILW; this could have implications for the volumes of storage or repository space (or both) that will be required. Over the whole fuel cycle reprocessing can reduce the volume of LLW because if uranium and plutonium are recycled less uranium ore needs to be mined. This off-sets the small additional radioactive discharges to the air and sea at the reprocessing plant. The following table shows the volumes of LLW, ILW and HLW arising from 1 GW(e) year power generation for a fuel cycle with reprocessing and complete recycling of uranium and plutonium, and a once-through cycle[54]. If the uranium and plutonium produced by reprocessing are not recycled the situation is very different because of the large repository volume that is likely to be required to accommodate these fissile materials (see para 7.42).

Table 4 Waste arisings
Waste type
Waste volume (cubic metres)
     Reprocessing Once-through
LLW15,15220,060
ILW3611
HLW540

7.4 Reprocessing involves the chemical and physical separation of uranium and plutonium from spent nuclear fuel. The fuel rods are first removed from their support structure and are chopped into sections. These sections are then dissolved in nitric acid in order to separate the fuel from its cladding. The resulting liquor undergoes chemical processing (e.g. using ion-exchange and organic solvents) and physical techniques (e.g. filtering and centrifuging) to separate the plutonium and uranium, that can be re-used, from various waste streams containing the fission products and fuel cladding.

7.5 The initial impetus behind reprocessing was to supply plutonium for research and the manufacture of nuclear weapons. More recently, reprocessing has been linked with the more positive image of recycling (e.g. in advertisements on British television by BNFL) to show how nuclear power can be a sustainable alternative to fossil fuels. There is a variety of reasons for reprocessing spent nuclear fuel:

·  To produce plutonium (e.g. for weapons, fast reactors or mixed oxide fuel, MOX).

·  As a waste management strategy for dealing with otherwise unstable fuel or fuel assemblies (e.g. for dealing with Magnox fuel).

·  To reduce the environmental impact on uranium mining areas, by reducing uranium demand.

·  To recover uranium for use in the manufacture of new fuel (which conserves supplies of uranium, may give a degree of fuel supply security, may be cheaper if the price of mined uranium is high, and can save on fuel enrichment[55]).

·  To maintain a technological and commercial advantage over competitor nations.

·  To generate income, much of which could come from overseas customers.

·  To create employment.

7.6 The United Kingdom currently has three reprocessing plants: two major facilities at Sellafield for reprocessing uranium oxide fuels and Magnox fuel, and a minor facility at Dounreay for fuels containing a high proportion of plutonium or highly enriched uranium (see Box 3). The United Kingdom reprocesses spent fuel from its Magnox reactors, advanced gas-cooled reactors (AGRs) and some research reactors. As yet it has not reprocessed any spent fuel from submarine reactors or from the Sizewell B pressurised water reactor (PWR). BNFL Sellafield is reprocessing substantial quantities of fuel from overseas customers, particularly oxide fuels from PWRs and other light water reactors in countries such as Japan.

7.7 Because of the reprocessing programme, spent reactor fuel in the United Kingdom is not considered to be a waste. A similar policy in favour of reprocessing has also been adopted by other countries including Japan, France, Belgium and India. A number of eastern European countries also favoured reprocessing in the past, although most of their contracts were with the former Soviet Union and it is now not clear if or when reprocessing will be carried out. The two principal countries engaged in commercial reprocessing are now the United Kingdom and France.

7.8 Some countries (including Canada, Sweden, Finland, and Spain) have decided not to reprocess their spent fuel; the US does not reprocess the spent fuel from its civil reactor programme. With no re-use envisaged, the spent fuel is declared as waste. As it is not usually proposed to remove the spent fuel from its support structures, the whole of the fuel assembly becomes what in the United Kingdom would be termed high level waste (HLW).

7.9 For those countries which do reprocess, and regard plutonium as an asset, one advantage is the reduced volume of HLW that must be dealt with (see paragraph 7.3). Disadvantage are the intermediate level waste generated by reprocessing, the discharges of radioactive effluents to air and sea, and the effort that must be devoted to the storage of plutonium.


Box 3: Reprocessing in the United Kingdom

Magnox

Magnox reactors use un-enriched uranium metal fuel rods enclosed in a cladding of magnesium alloy. This fuel is reprocessed in the B205 plant at Sellafield. Reprocessing of Magnox fuel started at Sellafield in 1952 and more than 40,000 tonnes have been reprocessed since then. Reprocessing is likely to continue for at least another 10 years as the remaining Magnox power stations are not expected to close before 2007. One reason why the spent fuel is reprocessed is because of the technical problems which result from contact with water: the fuel cladding corrodes, and the fuel reacts with water to produce uranium hydride (which can ignite spontaneously in air). Contact with water occurs because the spent fuel is cooled under water after being removed from the reactor. Contact with water would also be likely in a repository. This suggests that reprocessing of Magnox spent fuel will have to continue until all of the fuel has been treated.

THORP

The Thermal Oxide Reprocessing Plant (THORP) treats uranium oxide fuel from advanced gas-cooled reactors (AGRs) and water-cooled reactors. The plant became operational in 1994 and it completed the final part of the regulatory approval process for commissioning in August 1997. After a steady build-up of activities, the aim is to achieve and maintain a through-put rate (the rate at which fuel is reprocessed) of 900 tonnes per year. It is expected that 7,000 tonnes of fuel will be reprocessed in the first ten years of operation. THORP cost £1.85 billion to build and is designed to have a 25 year lifespan (PP 286, 292).

The fuel for AGRs and water-cooled reactors is ceramic uranium oxide enriched with between 1.5 and 4 per cent fissionable uranium-235. AGR fuel rods are clad with stainless steel. The fuel for water-cooled reactors is clad in a zirconium alloy which, like the fuel itself, is very stable. Spent AGR fuel is more of a problem because of slow corrosion in the fuel rod cladding after exposure to water. It is technically difficult to completely dry the AGR fuel after immersion in water because the rods have graphite sleeves which retain moisture; it is also difficult to remove these sleeves without damaging the fuel itself (P 287, POST Report*, Sumerling 1997**).

Dounreay reprocessing

The UKAEA site at Dounreay includes a small commercial reprocessing facility. This deals with fuels from research reactors including the Materials Testing Reactor (MTR) and Prototype Fast Reactor at Dounreay, and MTRs owned by overseas customers. In March 1998, approximately 5 kg of highly enriched uranium and 9 kg of low enriched uranium were delivered to the site from a research reactor in Georgia (a former Soviet Republic). The transfer was made because of concerns over its safety in the light of political instability in the region. The material will be reprocessed and the Government announced that some of it could be used for medical purposes. Because of the circumstances of the transfer, the small amount of waste from reprocessing will not be returned to Georgia.

It was announced on 5 June 1998 that commercial reprocessing at the Dounreay site would cease once existing contracts had been completed. John Battle MP (then Minister for Science, Energy and Industry) told the House of Commons that the decision was being taken because there was no economic case for supporting commercial reprocessing at Dounreay in the long term (Commons Hansard, 5 June 1998, Col 385).

*Radioactive Waste-Where Next?, Parliamentary Office of Science and Technology, November 1997.

** Options for Disposal of Nuclear Fuel Waste: Alternatives Evaluated Abroad or Internationally,
TJ Sumerling, Safety Assessment Management Ltd., Report for SKB (Sweden), June 1997.


7.10

7.11 The discharges to the sea from Sellafield reached their peak in the mid-1970s as a result of corrosion in Magnox fuel assemblies which had been stored underwater for longer than desirable[56]. Since then, the introduction of new treatment plants has reduced the activity of discharges to sea by about a factor of one hundred[57]. The radiation doses from these discharges to the most exposed members of the public have decreased from a peak of about twice the national UK average natural background dose in the mid 1970s to about one tenth of the average natural background dose now[58]. At the 1998 Ministerial Meeting of the OSPAR Convention[59] in Portugal (22-23 July), the Government agreed to make further reductions in radioactive discharges to the sea by 2020.

7.12 Discharges of the fission product technetium-99 (a long half-life beta-emitter) have increased recently as a backlog at the Magnox reprocessing plant has been dealt with. BNFL are looking at technology for reducing these discharges, while technetium-99 from THORP is already stored with other HLW and will be vitrified (Commons Hansard, 28 July 1998, Col. 125).

Views of witnesses on reprocessing

7.13 Many witnesses, including the National Steering Committee for Local Authorities (p 220), Friends of the Earth (QQ 507, 526-529, pp 131-132, PP 319-321), Greenpeace (Q 417), Cumbrians Opposed to a Radioactive Environment (CORE, pp 106-107), the Consortium of Opposing Local Authorities (COLA, p 92), the Nuclear Control Institute (pp 231-232) and CND (p 55) said that reprocessing of spent fuel should be stopped. They argued that the products of reprocessing (i.e. separated plutonium and uranium) are not needed, and that reprocessing only compounds the existing problems because it generates more waste and environmental pollution. They also said that it creates further health and safety risks, is costly, and increases the possibility of nuclear proliferation. Greenpeace said, "The discharges from reprocessing to the air and to the sea are causing substantial problems...This is not a marginal problem. It is a major international problem and we should end it" (Q 418).

7.14 The Irish Government (pp 187-189) told us that it remained firmly opposed to any expansion of the nuclear industry and described the facilities at Sellafield as "part of an inexorable and increasing threat to Ireland's public health and environment" (p 187). They said that nuclear waste management policy should take more account of the effects on health and the environment beyond national borders, the precautionary principle should be observed at all times, and the polluters should pay for the burden placed on society and economy in Ireland (p 188).

7.15 A report by SERA (the Socialist Environment and Resources Association)[60] described reprocessing as a "powerful sacred cow within the British nuclear industry". The report stated that reprocessing creates over two thirds of Britain's annual arisings of ILW, large volumes of LLW and about 9 tonnes of plutonium a year (the latter requiring storage costing £1 million per tonne per year). SERA concluded: "The end result is we are shackled with high electricity bills and subsidies to support a process which has no economic or technical justification, which saddles us with more and more nuclear waste, which causes radioactive pollution throughout Europe, and which creates highly dangerous plutonium. It's time we stopped this nonsense." SERA's alternative to reprocessing would be dry storage of the spent fuel.

7.16 In general, the views of the nuclear industry are favourable towards reprocessing. British Nuclear Fuels told us that only about ten per cent of the volume of ILW expected to be accumulated by about 2050 would be avoided if nuclear power generation and fuel reprocessing were to stop immediately. Waste from past activities and decommissioning could not be avoided (pp 34-35). BNFL also argued that the product of reprocessing was useful: they told us that forty per cent of the fuel used in the AGRs had come from reprocessed Magnox fuel (Q 127).

7.17 When evaluating the benefits and impacts of reprocessing, BNFL and the Environment Agency said that the whole fuel cycle, from mining uranium to eventual disposal, should be considered. The Environment Agency added "one would be quite justified in considering the (impact of the) totality of a nuclear fuel cycle on the environment, not just your own environment but other people's environment" (Q 560). BNFL estimated that reprocessing resulted in only 75 percent of the LLW, and 80 per cent of the ILW and HLW, that would be generated if virgin materials were used and if spent fuel were disposed of directly (Q 127). Hence, BNFL regarded reprocessing as "a best environmental option" (Q 135).

7.18 The DETR told us that it was "not aware of any definitive study which clearly identifies either the reprocessing or direct disposal route for spent fuel management as being preferable from an environmental point of view". Those studies which had been undertaken depended on making a plethora of assumptions and were complicated by there being no single measure for environmental impact (PP 298-300). For AGR fuel, RWMAC compared the options of early reprocessing, delayed reprocessing and not reprocessing at all and concluded that "all three options have impacts which are small and comparable within the bounds of the uncertainties in the estimates" (11th Annual Report, 1990).

7.19 BNFL said that reprocessing gave various benefits for the natural environment of the United Kingdom (P 287, PP 292-293):

·  it allowed plutonium to be burnt in reactors (thus reducing the total inventory of plutonium in the world when compared to using fresh uranium fuel);

·  it reduced the volume of highly active waste that had to be disposed of;

·  it conditioned wastes in forms that are safe to dispose of or store;

·  through overseas contract income, reprocessing had substantially reduced the costs of treating the United Kingdom's historic and future nuclear waste.

7.20 BNFL also told us that it would be technically possible to construct a reprocessing plant which was designed for waste management purposes, rather than for the recovery of fuel quality uranium and plutonium. They said that a variety of technologies had already been researched, but further development would be needed if this were to be pursued. Such a plant would only require a one-stage chemical separation process and, if this was the desired objective, a new facility might make better economic and safety sense than making modifications to THORP (P 287).

7.21 The UKAEA agreed that reprocessing was still a safe and credible option for the United Kingdom and that it should continue to be used to convert Magnox fuel into a more stable form for the long term. The UKAEA also said: "in terms of modern power stations then clearly there are the equally credible options of either continuing to reprocess or to cease reprocessing and store the irradiated fuel" (UKAEA, Q 240).

7.22 Long-term dry storage of AGR fuel had been considered by Scottish Nuclear (now a subsidiary of the privatised British Energy) as an alternative waste management option to reprocessing. The company had started planning a storage site adjacent to its Torness power station in Scotland, but, for economic reasons, this was not pursued and Scottish Nuclear signed a contract with BNFL in 1995 for the management of all of its spent AGR fuel (Q 782). Nuclear Electric (the British Energy subsidiary in England) also made a similar deal. The combined contract is worth around £1.8 billion and will cover the reprocessing of approximately 4,700 tonnes of uranium fuel, ie all the spent fuel produced by AGRs over their expected lifetime (P 287, P 293). British Energy said that it was now for BNFL to decide whether to store or reprocess this fuel. The company was aware of the various arguments against reprocessing voiced by environmentalists and interest groups, but they had no reason to disagree with the original inquiry findings which had said that THORP was environmentally sound (QQ 777-784).

7.23 The economic arguments for continuing with reprocessing, and to continue operation of the THORP plant in particular, were presented by BNFL and the National Campaign for the Nuclear Industry. The economic base of west Cumbria is strongly linked to the fortunes of BNFL: it is the largest employer in the area and many of these jobs are linked to reprocessing activities (NCNI, pp 212-213). BNFL said that it thought there was a healthy future for THORP: the company said it has a 16 year order-book for THORP worth over £12 billion; there are good prospects that a further £5 billion of orders can be secured; and a nuclear renaissance was expected in the next century, led by countries such as China (Q 127, P 292). A profit of at least £500 million (in 1992 money) was expected in the first ten years of operation after accounting for all capital and decommissioning costs (P 286). BNFL concluded that THORP is justified on the basis of the economic benefits and lack of serious environmental disbenefits (QQ 130-135)[61].

7.24 An alternative view on the economics of THORP was published during the course of our enquiry: Future THORP Available Cash Flows, M.J. Sadnicki for the National Steering Committee of Nuclear Free Local Authorities, April 1998. In this paper it is calculated that THORP could only make a profit if several parameters such as the fuel through-put rate and contract prices were at the upper end of their possible range.

MIXED OXIDE FUEL

7.25 Mixed oxide fuel (MOX) is the principal means by which plutonium, separated from spent fuel during reprocessing, could be used for power generation. An alternative option, use in fast breeder reactors, is discussed briefly in the next section. MOX is important in waste management terms because it allows the re-use of some of the material in spent fuel that would otherwise be classified as waste. Using MOX could reduce the need for 'virgin' uranium in reactor fuel, and thus could have an important impact on those areas where uranium is mined. MOX could also have advantages for decreasing the risk of nuclear proliferation: locking up plutonium in MOX would make it less accessible for weapons production, although still accessible by chemical means to the most determined.

7.26 Typically, MOX contains 5-8 per cent of plutonium in oxide form mixed with uranium oxides. The isotope plutonium-239 is fissile and, like uranium-235 in standard reactor fuel, provides the driving force for the fission reactions needed to generate heat. A number of countries are operating reactors using MOX, although the United Kingdom has not yet done so (see Box 4). No reactors have yet been built with MOX specifically in mind from the outset, but it has been used successfully in some water-cooled reactors. Where MOX has been used it has been as part of a mixed fuel load with normal reactor fuel, with up to one third of the load being MOX. Extra safety procedures, and in some cases extra radiation shielding, are required when MOX is used because spent MOX fuel is more radioactive and more radiologically hazardous than spent uranium metal or spent uranium oxide fuel due to the presence of greater concentrations of actinides and fission products.

7.27 MOX can be used in a "once-through" fuel cycle or in a cycle with reprocessing. The number of times that MOX fuel can be reprocessed is limited by the build-up of the heavier actinide elements in the fuel and the maximum is three or four. Thus in both the once-through and reprocessing cycles spent MOX fuel arises as waste; in the reprocessing case there is also liquid HLW for solidification and disposal.

7.28 In 1996 the world-wide MOX fabrication capacity was estimated by the nuclear industry to be around 124 tonnes per year. Estimates for expected capacity in the year 2000 range from 439 tonnes per year (by industry) to 229 tonnes per year (by the World Information Service on Energy).[62]
Box 4: Some national policies for MOX
BelgiumTwo out of seven reactors are loaded with 20 per cent MOX. There is a commercial scale MOX fabrication plant at Dessel.
France16 out of 56 reactors are currently licensed to use MOX, and 12 of these have been loaded with 30 per cent MOX. France operates most of the world's capacity for MOX fabrication (including 'MELOX', the world's largest MOX plant). A further plant is planned.
Germany12 out of 20 reactors are licensed for MOX; seven of these are using this fuel. In January 1999 the coalition parties announced they would ban reprocessing fuel from January 2000 and would amend the existing law to allow a phasing out of nuclear power.
JapanTwo out of 53 reactors have been partly fuelled with MOX for demonstration purposes. It is expected that MOX will be used in three or four reactors by the year 2000, and ten reactors by year 2010. One small MOX fabrication plant is in operation and a larger plant planned.
SwitzerlandIt is expected that two out of Switzerland's five reactors will be partly loaded with MOX by the end of the century.
U.K.The UK has no present plans to use MOX. The Sellafield MOX fabrication plant is constructed but not yet licensed.
U.S.Investigating the possibility of using MOX in commercial reactors as a means of disposing of plutonium from their nuclear weapons programme.
OthersThe Netherlands, Sweden, and Canada have no plans to use MOX in their reactors.
Sources: International MOX Assessment, 1997; Foreign Press Centre, Japan, 20 February 1998.

Views of witnesses on MOX

7.29 BNFL is just completing a new MOX fabrication plant, the Sellafield MOX Plant (SMP), which is expected to have a production capacity of 120 tonnes of MOX per year. The Environment Agency has decided that its discharges should be authorised (ie that the plant can start operating) but the authorisation is awaiting ministerial decision. The Environment Agency told us that it had conducted a two month consultation exercise and had evaluated the technical case presented to it by BNFL. It had also contracted the PA Consulting Group to examine the economic case for the plant (QQ 577-587). The public version of the economics report concluded that the plant will produce significant levels of operational profit: "very unlikely to be less than £100 million, exceeds £300 million in many options, and on average amounts to £230 million"[63]. Friends of the Earth said that "the economic justification presented for this plant [the SMP] is based upon information withheld from the public domain and which does not consider alternatives" (p 320).

7.30 BNFL told us that Japan would like all of its plutonium from reprocessing returned in the form of MOX, and Germany was heading the same way (Q 139)[64]. MOX burnt in civil reactors might be a way of dealing with plutonium stocks in the former Soviet Union (Q 140), although it would take several decades to do so.

7.31 In the United Kingdom, British Energy said that it might consider using MOX at Sizewell B although a number of issues needed to be addressed. These included steps to minimise radiation dose from the fuel assemblies, appropriate security arrangements during fuel transport and handling, and addressing all of the regulatory matters involved in licensing (P 277). The short-term cost of using MOX at Sizewell would be higher (because MOX fabrication is expensive), but there would be long-term savings from reducing the amount of plutonium which would eventually require disposal (QQ 809-810). The Cumbria and North Lancashire Peace Groups disagreed, arguing that spent MOX posed greater problems for ultimate management because it contained a higher proportion of long-lived actinide elements (p 105)[65]. British Energy concluded that "the economics of MOX use in Sizewell B are not currently competitive with uranium fuel" (P 277). Utilisation of MOX in AGRs had also been reviewed but was not considered to be practicable (P 277).

7.32 Because of international agreements on nuclear proliferation and the transfer of plutonium, MOX that is intended for sale overseas can only be produced using plutonium supplied by the country wishing to use that fuel. BNFL told us that there would be a significant world market for nuclear power in the next century even if only the most conservative estimates of energy demand were to be met: "under these circumstances the plutonium would represent a valuable potential source of energy" and "the potential market [for MOX] exceeds the amount of plutonium that will be available" (P 289). In contrast, the IAEA estimates that under free market conditions for MOX the world stock of separated civil plutonium could be reduced from the current level of 170 tonnes to about 50 tonnes by 2013[66]. Without a free market IAEA expects the world-wide rate of production of plutonium and its rate of use as MOX to come into balance in a few years' time; until then stocks will continue to increase.

7.33 BNFL also said the environmental advantages of using MOX make it important when considering carbon dioxide and other emissions: one tonne of plutonium when recycled as MOX contains the same amount of energy as 2 million tonnes of coal (P 293). The BNFL web site states: "The Sellafield MOX Plant is a recycling plant. Using product from reprocessing, it will have the capability, during its 20 years lifetime, to produce around 2,000 tonnes of nuclear fuel creating the equivalent of 640 terawatt hours of electricity—enough to provide electricity to the whole of the United Kingdom for more than two years".

7.34 On the other hand the Royal Society report[67] noted that using MOX does not necessarily reduce the amount of plutonium in existence. New plutonium will be generated from uranium-238 in the fuel as it captures neutrons released during the fission of plutonium. The balance between consumption and creation would depend on the isotopic content of the fuel, the fraction of the fuel load that is MOX, and the fuel burn-up rate. Thus MOX fuel itself could be reprocessed to recover plutonium for future use (although the build up of higher mass actinide elements restricts the number of times that MOX can be reprocessed, see paragraph 7.26). The report also stated: "Reprocessing of spent fuel solely to produce plutonium for recycling as MOX is not economic. But given that reprocessing has been carried out and the plutonium is available, then the extra cost of fabricating MOX fuel (as compared with enriched uranium fuel) might be justified in view of the savings in uranium and enrichment costs"[68].

PLUTONIUM STOCKS

7.35 As discussed above, plutonium is one of the products of reprocessing spent nuclear fuel. In the United Kingdom, plutonium is separated out from the recovered uranium during reprocessing, it is converted into insoluble plutonium dioxide, and it is kept in secure storage at Sellafield.

7.36 The Royal Society estimated that the United Kingdom now has 53.5 tonnes of separated civil plutonium in stock. This includes plutonium held by BNFL for its overseas reprocessing customers (thought to be less than 5.5 tonnes). Most of the current stocks have been generated from the reprocessing of Magnox fuel. By 2010 the stock will have risen to over 100 tonnes and, at that time, the United Kingdom will hold about two thirds of the world's separated civil plutonium. The overall global inventory of plutonium by 2010 will be over 2,000 tonnes, but almost all of this will be locked up in spent fuel or MOX and thus it will not be readily accessible[69].

7.37 In terms of waste management, plutonium is a special case because of the nuclear proliferation risk that it poses. Also, if it were to be disposed of or stored indefinitely, there is a remote risk of a non-explosive critical nuclear reaction occurring should enough plutonium come together in the right physical configuration. Plutonium also presents a relatively high radiological hazard because of the damage it can cause (through alpha-particle radiation) if it is inhaled into the human body.

7.38 The United Kingdom does not categorise plutonium as a waste, but it is given a zero value in BNFL's balance sheet. The potential for using plutonium in MOX has already been discussed and there could be an even greater potential for future use in fast breeder reactors. Fast reactors use a fuel rich in plutonium (20-35 per cent)[70] plus non-fissile uranium-238. In theory, fast reactors are around sixty times more efficient than other reactors and, in the 1970s they were expected to be a major source of power for the future[71]. However, there have been a number of technical and economic problems with fast reactors which has made their future uncertain.

7.39 The United Kingdom shut down its prototype fast reactor at Dounreay in 1994. Development of fast reactors in Japan has hit problems following a sodium leak at the Monju prototype fast reactor in December 1995. In 1998 the new French Prime Minister, Lionel Jospin, confirmed that France was permanently shutting down its Superphenix fast reactor for "economic reasons"[72].

Views of witnesses on plutonium

7.40 BNFL told us that storage of separated plutonium for possible future use was not a problem. They spend £10 million annually on security and safeguards associated with plutonium on the Sellafield site and that, "guarding one tonne of plutonium is as costly as guarding 50 tonnes". Over 35 per cent of these costs were currently being met by overseas reprocessing customers. BNFL said, "The issue surrounding plutonium is not the quantity stored, but the international safeguards and security regime to which the stored material is subjected. The better funded the regime then the better the safeguards" (PP 292-293).

7.41 The UKAEA told us that it did not see fast reactors being required for the next 50 to 100 years (Q 291). This, and the fact that MOX is not yet used in the United Kingdom, means that currently there is no significant demand being placed on our plutonium stocks; indeed stocks are increasing. It has been argued that plutonium might therefore be more of a liability than an asset. Some witnesses, including Friends of the Earth, consider that plutonium is a waste product from reprocessing (P 319). The Science Policy Research Unit at the University of Sussex estimated that managing our plutonium stocks as HLW would cost the United Kingdom around £2.3 billion (in 1997 money) by the year 2105[73].

7.42 Again, if plutonium is regarded as a waste, and if disposal is advocated, then some witnesses suggested that this could cause problems. Sir John Knill and others told us that natural processes could re-concentrate plutonium, so the best option would be to distribute it as small particles within other wastes and then distribute these wastes throughout a repository. The amount of plutonium in normal wastes was not thought to present too much of a problem, but the safe disposal of separated stocks would be another matter entirely. Sir John thought that some special method of disposing of plutonium may be required in the future (Q 1033).

7.43 The DETR is also considering what the implications would be if plutonium is classified as a waste in the future. They have commissioned QuantiSci to conduct a study into the disposal of HLW, spent fuel and other materials, including plutonium and uranium from reprocessing. A concern that is being investigated is whether more than one deep repository would be required in order to cope with the potential waste volumes (Q 161). This could have significant implications for the United Kingdom's nuclear waste management strategy. The interim report from QuantiSci[74] states that if these materials are classified as wastes and are designated for disposal in a repository, then "there would be a substantial impact on the required repository design and thus size of the supporting R&D programme, particularly if safeguards and criticality issues become more important, due to the inclusion of more plutonium". QuantiSci added that, "Whilst it would be possible to include additional wastes late in a deep repository development programme, this could result in sub-optimal decisions being taken, so the types of waste to be included in the programme should be specified as early as possible".

7.44 In 1998 the United Kingdom became the first nuclear weapons state to declare the size of its defence-related stocks of fissile materials. Our stock of defence-related plutonium was said to be 7.6 tonnes. In the Strategic Defence Review, when these figures were released, it was announced that there was a surplus of 4.4 tonnes of plutonium including 0.3 tonnes of weapons-grade material[75].

7.45 In its report on The Management of Separated Plutonium, the Royal Society considered that there was an international consensus against having a large stock of separated civil plutonium because this posed a significant environmental and security risk, and left "an open-ended legacy for future generations". The Royal Society concluded that the Government should review its strategy and options for stabilising and then reducing the stocks of plutonium, subject the options to independent review, and maintain R&D capabilities so that competing options could be evaluated. The various options discussed included: use of MOX in current reactors, building new reactors specifically designed for MOX, using plutonium from United Kingdom stocks in MOX sent abroad, disposal of plutonium in a repository, and use as fuel in some advanced (fast) reactor whose fuel cycle eliminates plutonium.


54   From Butler, Gregg, Nuclear fuel: recycle or dispose? How? Where? When? Interdisciplinary Science Reviews Vol.23 No.3 p292-297 (1998). Back

55   Where reactor fuel enriched with uranium-235 is used, the spent fuel is still enriched relative to naturally occurring uranium. Thus, less re-enrichment is required to produce new fuel from this material. Back

56   RWMAC, 11th Annual Report, 1990. Back

57   BNFL Annual Report and Accounts, 1998. Back

58   MAFF and SEPA, Radioactivity in Food and the Environment in 1997, report RIFE-3, 1998.  Back

59   The Convention on the Protection of the Environment of the North-East Atlantic. Back

60   A Nuclear Waste: how ending reprocessing can benefit public health, protect the environment and save up to £6 billion. Report by SERA, Labour Environment Campaign, January 1998. Back

61   Evidence given in February 1998.  Back

62   The IMA Report: Comprehensive social impact assessment of MOX use in light water reactors. Final report of the International MOX Assessment, for the Citizens' Nuclear Information Centre, Japan, November 1997.  Back

63   Assessment of BNFL's Economic Case for the Sellafield MOX Plant, PA Consulting Group for the Environment Agency, December 1997. Back

64   Since taking that evidence, there has been a change of policy in Germany. Back

65   Spent MOX also has a higher thermal load than standard uranium spent fuel and thus requires a longer period of cooling before it can be reprocessed or put in storage. In addition, the beta and gamma activity is up to six times higher and the plutonium content five times higher than spent uranium fuel (Nuclear Fuel, Volume 23, No. 4, February 1998). Back

66   IAEA Bulletin 40/1/98.  Back

67   The Management of Separated Plutonium, The Royal Society, February 1998. Back

68   The Royal Society, ibid. Back

69   The Royal Society, ibidBack

70   Alternative fuel cycles using thorium and uranium could also be used. Back

71   Royal Commission on Environmental Pollution 6th Report, 1976, Nuclear Power and the Environment.  Back

72   General Policy Statement given by Lionel Jospin, 19 June 1998. Back

73   Managing United Kingdom Nuclear Liabilities, SPRU, October 1997. Back

74   QuantiSci, High-Level Waste and Spent Fuel Disposal Research Strategy: Project Status at the Half-Way Point, report DETR/RAS/98.006, May 1998. Back

75   UK stocks of other nuclear materials were also announced including highly enriched uranium (1.61 tonnes) and depleted, natural and low enriched uranium (84,000 tonnes). HC Hansard, 2 June 1998, col. 163-164. Cm 3999, Strategic Defence Review.  Back


 
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