Select Committee on Science and Technology Third Report


10 March 1999

By the Select Committee appointed to consider Science and Technology.

Ordered to Report

Management of Nuclear Waste

  1. With the rejection in 1997 of the Nirex planning application for a rock characterisation facility at Sellafield, as a step towards the development of a deep repository, the United Kingdom was left with no practical plan for the disposal of most of its nuclear waste. This prompted the Committee to enquire into the management of nuclear waste in the United Kingdom.
  2. The bulk of nuclear waste that exists now and is certain to arise in future originates from past military and civil nuclear programmes. The problem exists and has to be solved. It could not be avoided by deciding today to discontinue nuclear power production or the reprocessing of spent fuel (Chapter 2).
  3. A dominant characteristic of much nuclear waste is the period of hundreds of thousands of years over which it must be effectively isolated from people and the environment. This poses problems of technical assurance and public acceptance in a field which is unique in its demands (Chapter 2).
  4. The long time-scales involved might be thought to be a reason for postponing decisions. The contrary is the case, since existing storage arrangements have a limited life and will require replacement, and eventually the repackaging and transfer of stored waste. Reliance on supervision for very long periods increases the probability of human error (Chapter 3).
  5. We received a great deal of evidence on the technical issues and conclude that phased disposal in a deep repository is feasible and desirable. This view is shared by the authorities in other major nuclear nations facing the same problems and by the international agencies dealing with nuclear waste. The phased approach which we recommend would allow decisions to be taken in a considered way as technical confidence and experience develop, and would avoid premature decisions which may be difficult to reverse (Chapter 4).
  6. The future policy for nuclear waste management will require public acceptance. We examined ways in which this is being approached in other countries and we considered means to achieve it in the UK. Central to this is the need for widespread public consultation before a policy is settled by Government and presented to Parliament for endorsement. We believe that our report will provide a useful input to such a consultation process. We draw attention to the further need to secure local acceptance of a recognised national need and we suggest some ways of achieving this (Chapter 5).
  7. Present policy for nuclear waste management is fragmented. There are wastes for which no long term management option has yet been decided and there are a number of significant materials, for which no use is foreseen, which are not categorised as waste at all. This leads to uncertainties in the planning of future facilities and to the continued storage of hazardous materials in an essentially temporary state. Until the fate of these materials is settled, and the capacity of potential sites is identified and explored, it will not be possible to know whether one deep repository will suffice. In the case of plutonium we draw attention to the large and growing stock level and recommend the excess over foreseeable need be declared as waste (Chapter 7).
  8. These problems require changes in the present organisational structure for nuclear waste management. We recommend the establishment of a new body, a "Nuclear Waste Management Commission", charged with the development of a comprehensive strategy. This should be done through public consultation, with the object of defining a widely acceptable solution. If, as we recommend, phased geological disposal is adopted, there will be a need for a "Radioactive Waste Disposal Company" with the remit to design, construct, operate and eventually close the repository (or repositories). When these two organisations are established they will subsume the roles of Nirex and RWMAC. We believe it to be essential that Government takes a positive role in the development and implementation of such a strategy, and that Parliament endorses the strategy and renews its support regularly during implementation (Chapter 6).
  9. The problem is one for which no precedent exists. It requires a determined effort on the part of Government and the public to arrive at a solution without unnecessary delay—a solution which leaves a clear and manageable situation and protects future generations and their environment.


1.1 On 17 March 1997, the Secretary of State for the Environment upheld Cumbria County Council's refusal to grant Nirex planning permission for a Rock Characterisation Facility (RCF) at Sellafield. This "stopped dead in its tracks the search for a long-term disposal route for intermediate level radioactive waste" (POST Report 106)[1]. Since the 1976 report by the Royal Commission on Environmental Pollution (RCEP)[2], it has been Government policy to pursue the disposal of solid radioactive waste as the long-term solution to nuclear waste management problems. The purpose of our enquiry was to see where the rejection of the RCF planning application left that policy for the future management of radioactive wastes in the United Kingdom.


1.2 In 1976 the RCEP[3] stated, "there should be no commitment to a large programme of nuclear fission power until it has been demonstrated beyond reasonable doubt that a method exists to ensure the safe containment of long-lived highly radioactive waste for the indefinite future". The report continued, "We are clear that the responsibility for developing the best strategy for dealing with radioactive waste is one for the Government, and specifically for a department concerned to protect the environment". It recommended a statutory body, the Nuclear Waste Management Advisory Committee, to advise the Secretary of State. It also recommended an executive organisation to develop and manage the radioactive waste disposal facilities, the Nuclear Waste Disposal Corporation. This latter body would meet the cost of rendering wastes environmentally acceptable through charges levied on the nuclear industry. The Royal Commission concluded its discussion on nuclear waste with the words, "Radioactive waste management is a profoundly serious issue…There must be a clear, identifiable, policy centre and a means to ensure that the issues posed by waste management are fully considered at the outset of a nuclear programme, not dealt with many years after the decisions on developments that lead to the waste have been made and when options may have been effectively foreclosed".

1.3 Following the RCEP report, in 1978 the Government set up the Radioactive Waste Management Advisory Committee (RWMAC). In 1982 it established the Nuclear Industry Radioactive Waste Management Executive, which in 1985 became UK Nirex Ltd. Neither it nor RWMAC were the organisations envisaged by the RCEP report. In 1991, after several years of site evaluation and no little public controversy, Nirex selected Sellafield as its preferred option for the site of a deep repository for the disposal of radioactive waste. Nirex considered that a precursor of any such disposal facility should be the construction of a RCF to investigate in detail the conditions in the vicinity and to establish whether they were suitable. It was the planning permission for the construction of this research facility which was refused in 1997.

1.4 Between the report of 1976 and the events of 1997 waste management issues have been the subject of much study. One of the more recent reports is the Royal Society's "Disposal of Radioactive Wastes in Deep Repositories (November 1994). Prophetically, in the first of its principal recommendations, which dealt with the early stage of development of the science, was a warning that "the first exposure to alternative interpretations and to the inadequacies of supporting data could come in the confrontational climate of a public inquiry. This could set back the entire programme, with serious consequences for the achievement of satisfactory solutions to the problems of radioactive waste management and disposal in the UK". The report went on to argue the need for transparency and openness with data, an issue which has also been significant in our own enquiry. The Royal Society's latest report on nuclear issues, Management of Separated Plutonium, came out in February 1998 after the commencement of our enquiry. Again, this has been influential in our proceedings because the continuing production and storage of plutonium could have long-term implications for the United Kingdom's management strategy for nuclear waste. The House of Lords Select Committee on the European Communities report, Radioactive Waste Management, in 1988[4] identified the issues of public confidence and public acceptability as keys to future progress. It recommended that deep geological disposal be pursued with determination. "No better solution is discernible and it is impossible to wait any longer for some hoped-for unspecified alternative" (para 210). These reports, together with many others including in particular the POST Report published at the commencement of our enquiry and the many constructive reports produced before that by RWMAC, have all contributed greatly to our work.

1.5 Notwithstanding the many reports published in the intervening years, radioactive waste management is no less a profoundly serious issue now than it was when examined by the RCEP in 1976. Much time has been allowed to pass, many recommendations have not been acted upon, and more waste has been, and is still being, created. There is therefore a large legacy of existing waste that present a serious challenge. This is a major problem that has been dealt with in an ad hoc way for decades. Currently, delays in finding a long-term solution mean that new waste stores, intended as a temporary measure pending construction of a permanent facility, are having to be built. If the delays continue, even more will be needed and some existing stores will need to be replaced. In November 1998, towards the conclusion of our enquiry, the Health and Safety Executive published a report[5] which identified some current waste management issues. Our enquiry is not primarily concerned with issues affecting the safety of stored wastes but the HSE report serves to highlight the need for a coherent waste management strategy. Overall, from the standpoint of immediate safety, the present situation is under control, but the size of the task ahead and the time-scale of any foreseeable solution make a political decision on future strategy a matter of urgency.

This Report

1.6 Our report is divided into four parts. The first describes the present situation, giving some of the history and background to the current wastes in the United Kingdom's inventory. This part also outlines some of the ways of dealing with nuclear waste that have been used in the past or advocated to us. In the second part we analyse the options for waste management in the UK from the technical perspective, reaching conclusions on the preferred method. We then look more closely at the constraints on implementing this waste management strategy, in particular the question of public acceptability. We conclude this part with a review of policy and make recommendations for the future. In the third part we consider related but separate waste management issues, particularly reprocessing of spent nuclear fuel and the stock of plutonium. The report concludes with a summary of our recommendations.

1.7 A general introduction to radioactivity, nuclear fission and the problems they pose is given in Box 1. The membership of the Sub-Committee which produced this report is listed in Appendix 1 and the Call for Evidence we issued is set out in Appendix 2. The Enquiry was based on the assistance of a wide range of individuals and organisations who responded to the Call for Evidence: these are listed in Appendix 3. We are most grateful to them all for their time and effort. We also wish to express our thanks to those whom we visited, who made presentations or provided briefing: in particular British Nuclear Fuels plc (BNFL) Sellafield; the UKAEA, Dounreay; and the many people who were so generous with their time and hospitality during our visits to the US, Canada, Sweden and France (see Appendix 4). Thanks go also to the staff of the High Commission in Canada and Embassies in the other countries for their assistance with our overseas visits. Particular thanks go to our Specialist Adviser, Ms Marion Hill of W S Atkins, without whose experience, expertise, and all manner of assistance, the production of this report would have been immeasurably more difficult. We very much appreciate her help and that of everybody who has contributed to this Enquiry.

1.8 A glossary of terms and acronyms is in Appendix 5.

Box 1: An introduction to radioactivity

The nature of radioactivity

The nucleus of an atom may be considered to contain neutrons and protons, the number of which is called the atomic number. Radioactivity originates from the nuclei of atoms that are unstable because they contain too few or too many neutrons. In order to attain stability, these 'radionuclides' spontaneously eject nuclear matter (radiation) as either alpha-particles (nuclei of helium atoms), beta-particles (electrons), gamma-rays (electromagnetic radiation), or neutrons. The eventual result is that unstable atoms transform themselves into more stable atoms of the same or other elements. For example, when the naturally occurring radionuclide samarium-147 (with atomic number 147) ejects an alpha-particle (with atomic number 4), unstable samarium atoms are transformed into stable atoms of neodymium-143.

The transformation illustrated above is the process of radioactivity. In some cases (samarium-147 is an example) a radioactive 'parent' nuclide decays to a stable 'daughter' product. For the heavier radionuclides, however, a chain of daughter products may be involved, only the last of which will be stable. For example, in the naturally occurring uranium chain the parent is uranium-238, the radioactive daughter products include uranium-234, thorium-230, radium-226, lead-210 and polonium-210, and the end of the chain is a stable form of lead. The decay pattern of a single radionuclide is exponential with time, is characteristic of the particular radionuclide, and is precisely known.

A useful measure of the decay rate of a radionuclide is the 'half-life', which is the time taken for half the atoms in a sample of that radionuclide to transform themselves. For a given radionuclide, activity and half-life are inversely proportional. The more active the radionuclide, the shorter the half-life, so the faster the decay. After a sufficient time has passed, almost all of a radioactive sample will have decayed to stable products and be no longer radioactive. That time, however, may be very long, perhaps millions of years or more if the half-life is large enough, and in that case the radioactivity will be correspondingly weak.

For example, the radionuclide krypton-85 has a half-life of 3934.4 days and it decays to the stable nuclide rubidium-85 by ejecting a beta-particle (electron). After one period of 3934.4 days, 50% of the atoms in a sample of krypton-85 will have transformed themselves into rubidium-85; after 10 half-lives (107.8 years) the sample will contain just 0.1% krypton-85 and 99.9% rubidium-85, and the radioactivity of the sample will have decreased in proportion to the amount of krypton remaining.

The emission of alpha- and beta-particles is accompanied by a release of energy, most of which manifests itself in the rapid motion of the particles ejected. This radiation is so energetic that it can strip electrons from surrounding atoms, and so 'ionise' them. The ionisation eventually dissipates itself as heat and as damage to the surrounding material. Further energy can be lost as gamma radiation, similar to X-rays but more energetic, which is also ionising.

Nuclear fission

The emission of free neutrons only occurs in a process known as nuclear fission, Here the nuclei of certain very heavy 'fissile' atoms, such as those of uranium, which have a large excess of neutrons over protons (143 neutrons and 92 protons in uranium-235), when excited by the capture of a neutron, split into two nuclear fragments, themselves highly radioactive, with the emission of a few free neutrons. In the fission process large amounts of energy are released, mainly in the form of energy of motion of the heavily ionising fission fragments. Thus a mass of fissile material exposed to neutron irradiation rapidly develops an admixture of 'fission products', and is therefore highly radioactive, at least initially.

The free neutrons emitted in the process of fission in a suitable mass of fissile material may themselves excite further atoms to undergo fission. This process is enhanced if the neutrons are first slowed down in a 'moderator' of light materials such as water or graphite. If the neutrons emitted per fission cause on average one further nucleus to undergo fission, the result is a condition known as 'criticality', a self-sustaining chain reaction. This process, properly controlled, is the basis of energy production in the nuclear power industry. In a nuclear reactor heat is generated in the fuel elements and their cladding by the ionisation caused by the fission fragments, and by the slowing down of neutrons in the moderator.

Such fission reactions are known to have occurred in nature about two billion years ago, when the natural abundance of the fissile uranium-235 (which has a half-life of 703.8 million years) was much higher than it is today.

The large fragments resulting from the fission process are in fact the nuclei of medium weight atoms. They are unstable and they absorb further neutrons, but do not undergo fission. In a nuclear power reactor they are the principal waste product of the power generation process. Eventually, due to their ability to absorb

neutrons, they build up in the nuclear fuel to such an extent that the fission process is no longer efficient. At this point the fuel must be replaced. However it may still contain substantial quantities of fissile material, which may be recovered and re-used as fuel if it can be separated from the waste fission products, and this is known as reprocessing.

Problems with radioactivity

The energy released during radioactive decay causes ionisation in the matter through which the radiation passes. The concern over radioactivity arises from the resulting damage that this can cause to surrounding material, especially living tissue. The term used to describe and measure this damage is 'radiotoxicity': it depends upon the rate of decay, the type of radiation emitted (alpha-particle or beta-particle, for example), its energy, and the nature of the surrounding material. For example, some tissues are more sensitive than others. In living organisms, radiation can kill cells, can disrupt genetic material (leading to cancers) and, if the dose and dose rate are very high indeed, such as in a nuclear explosion, can kill outright. In medicine, on the other hand, these properties are used in controlled conditions to treat cancer, by preferentially killing off tumour cells.

As will be clear from the above, radionuclides can continue to emit radiation for considerable periods of time. Thus, when radionuclides are used, measures must be taken to isolate them from the environment so as to limit their potential for causing harm. This applies not only to nuclear material while in use, but also after use, and to the waste products that result. For some long-lived radionuclides the period of isolation required may be thousands or even millions of years.

The measures that have to be taken to shield against the effects of radiation depend on whether it mainly consists of alpha-particles, beta-particles, gamma radiation or neutrons, or some mixture of these. Alpha-particles can only penetrate a few centimetres of air and they can be stopped by a sheet of paper or an outer layer of skin. Because they lose all their energy in a very short distance, alpha-particles can be very damaging to soft tissue (eg in the lung or digestive system if inhaled or ingested). Beta-particles can penetrate somewhat further, although they can be stopped by a few millimetres of plastic or metal. Again, they are dangerous inside the body. Gamma radiation, which often accompanies beta-particles, will easily penetrate the human body, and can do both internal and external damage. It can only be sufficiently attenuated by thick or heavy shielding, such as lead, concrete, or some metres of water.

Neutrons can also penetrate moderate thicknesses of matter. In the course of doing so, they slow down by repeated collisions with atomic nuclei in the material through which they pass. When a neutron collides with a nucleus there will be a considerable release of energy as the nucleus recoils. This in turn causes ionisation and further damage similar to that caused by an alpha-particle. The neutron is finally stopped only when it is absorbed by an atomic nucleus, a process made more likely if it has first been slowed down. As the neutron is absorbed it may cause fission (as described above), or the release of intense gamma radiation, or some other process. In their slowing down and eventual absorption, neutrons cause damage to both living tissue and reactor components.

Water is often used as a shield for neutron radiation because it can both slow down and absorb neutrons and, if it is extensive enough, can attenuate the associated gamma radiation.

Natural background radiation

Natural background radiation includes cosmic rays, gamma radiation from rocks and soils, radon emitted into the air from rocks and soils, and radionuclides (eg potassium-40) in foods. The background radiation doses which people receive depend on where they live, their habits and their diet.

For most people in the United Kingdom natural background doses are much higher than the dose they receive from all man-made sources of radiation. The average natural background dose to an individual in this country is 2.2 millisieverts per year*. The range of background doses is from about 1 millisievert per year to about 100 millisieverts per year; the highest doses are in areas where radon levels are high, such as parts of Devon and Cornwall. The average dose to a member of the public from nuclear power is about 0.0004 millisieverts per year and the highest dose is about 0.2 millisieverts per year**.

*The unit of radiation dose is the sievert, which is defined in terms of the energy deposited per unit mass of body tissue, with weightings for the potential of the type of radiation to cause damage and for the sensitivity of tissues. A millisievert is one thousandth of a sievert.

**Data taken from National Radiological Protection Board report NRPB-R263 and MAFF/SEPA report RIFE-3.

Parliamentary Office of Science and Technology (POST) Report 106, 1997: Radioactive Waste - Where Next? Hereafter referred to as the POST Report. Back

2   Royal Commission on Environmental Pollution Sixth Report (1976); Chairman Sir Brian Flowers (as he then was): Nuclear Power and the Environment. Back

3   ibid.  Back

4   Session 1987-88, 19th Report, HL Paper 99, July 1988. Back

5   Health and Safety Executive Safety Directorate: Intermediate Level Radioactive Waste Storage in the UK: A Review. Back

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