Select Committee on Science and Technology Appendices to the Minutes of Evidence

Annex: 2002-03 Fusion Income to Culham (£M, approx)


National Programme
JET: Operations, Miscellaneous



  Deuterium and tritium are isotopes of hydrogen in which, in addition to the proton in normal hydrogen, the nucleus has one or two neutrons respectively. Deuterium combining with tritium (to produce helium, neutrons and energy) is the most likely fusion reaction to be used in future fusion power plants as it occurs at the lowest temperatures—around 100 million degrees Centigrade. D-T fuel has been used in JET and in a US tokamak TFTR which has now been dismantled.

  Very large quantities of deuterium are available from seawater. Tritium does not occur naturally, because it is unstable to radioactive decay. In a power plant, tritium would be produced by the escaping neutrons reacting with a blanket containing a lithium compound.


  European Atomic Energy Community. Most of the funding for JET is from EURATOM. Approximately one quarter of the funding for the UK national programme is from EURATOM (the remainder is from OST/EPSRC), though this fraction will decline as the EURATOM programme focuses on ITER construction.


  Until recently it has been envisaged that fusion will be developed in a sequential manner from JET, through ITER and then a device that demonstrates electricity generation and tests power plant components (DEMO) to a prototype power plant (PROTO). This would have taken about 50 years. However, growing environmental and security of supply concerns have led to pressure for development of fusion as an energy source on a more rapid timescale. In November 2001 a group of European experts, chaired by the Chief Scientific Adviser to the UK Government, examined for the Council of Ministers a "fast track" to fusion power. In this DEMO and PROTO would be combined, reducing the timescale by about 20 years. This would require increased focus on electricity generation technologies in the latter stages of ITER and, in parallel to ITER, testing in IFMIF of how materials respond to the sustained doses of fusion-energy neutrons typical of a power plant.


  The International Fusion Materials Irradiation Facility (IFMIF) is a proposed device that would test the structural integrity of fusion power plant materials under appropriate neutron irradiation damage conditions. The required fluence of high energy neutrons would be produced by a beam of deuterium reacting with a lithium target. A conceptual design has been produced. In the Fast Track, IFMIF is built and operated in parallel to ITER, and not at a later stage.


  International Thermonuclear Experimental Reactor. A project funded under IAEA auspices, initially by four parties (EU, USA, Japan, Russia), to design a sustained burning tokamak plasma for physics and technological demonstration of fusion power. When the Engineering Design Activities were extended by three years in 1998, the US reduced its involvement and then withdrew, and the focus shifted to a design with reduced technical objectives and therefore reduced construction cost (- 4 Billion Euro). This design was completed in 2001. At the time of writing, the US is expected to rejoin, and China and Korea have both shown strong interest in joining. Negotiations on how ITER would be built and operated as an international project are nearing completion. There are candidate sites in France, Spain, Japan and Canada. Decisions on whether and if so where to build ITER are expected in 2003.


  Joint European Torus, sited at Culham. The world's largest tokamak, capable of mimicking the geometry of ITER, and associated facilities such as the tritium handling plant. Exploitation of the JET Facilities was by a separate legal entity, the JET Joint Undertaking, until this terminated on 31 December 1999. Since then JET has been operated by UKAEA, under contract to EURATOM, as a user facility for Task Forces of visiting European (including British) scientists.


  Mega Amp Spherical Tokamak at Culham. Experiments started in December 1999 and as well as addressing the feasibility of the spherical tokamak as a fusion device, help refine understanding of the physics of ITER operating regimes.


  Electrically neutral particles. High energy (14 MeV) neutrons are products of deuterium-tritium fusion reactions; in a power plant they would be used to produce tritium from lithium compounds and they would be the energy source for electricity generation.


  A very compact form of the tokamak in which the plasma appears almost spherical—it resembles a cored apple. Pioneered at Culham through first the START and now the MAST experiment. Several other countries have now built spherical tokamaks following the very successful experiments on START.


  Small Tight Aspect Ratio Tokamak at Culham. Holder of the world record plasma ß for a tokamak, where ß measures the ratio of plasma to magnetic energy. Experiments ceased in 1998, for completion of its successor, MAST.


  The most successful device yet found for magnetic confinement of plasma. Its magnetic field is made up from helical lines of force on toroidal surfaces, and is generated by currents in both external coils and in the plasma itself. In this magnetic bottle the very hot ionised gas required for fusion, the "plasma", is contained without minimal contact with materials surfaces (contact would cool the plasma and damage the materials). START, MAST, JET and ITER are all tokamaks.

Why Has Fusion Taken So Long?

  It is occasionally reported, most recently in the Economist, that the goal of achieving fusion as an operating electricity production system is never brought any nearer in spite of the R&D work that is done. This is used to discredit fusion R&D and imply that no progress is being made.

  These sentiments are so at odds with the observed continuous progress in fusion, especially in the last decade, and the positive outcomes of serious analysis of fusion R&D, most recently in the UK in reviews by A D Little and a panel of physics professors, that some look at what lies behind these statements is necessary.

  It is clear that when the time-scale to develop fusion is estimated, people form a view of how much work remains to be done and how long it would take to complete that work with foreseeable levels of R&D budget. This immediately gives one reconciliation between the actual major progress in fusion and the claims that it is not brought any closer in time. Assuming the rate of progress is given by the number of man years invested, then the time-scale for fusion development has two components: not only does it depend on the success of the research, it also depends on the rate at which the research is carried out, that is the R&D budget. Obviously, a declining budget will delay the development.

  In fact, world fusion expenditure has declined over the last 20 years. The reduction in the UK fusion R&D budget is one of the most extreme (a factor three in real terms; it is now, as a fraction of GDP, one of the lowest in the developed world), but other programmes such as the US have also reduced substantially. This in itself is sufficient to delay fusion development by many years.

  A related issue, particularly in the light of the strong international dimension of the fusion research programme, is the decision making progress. A natural outcome of declining budgets is a lack of firm decisions to fund the move on to the next stage in development because such decisions oppose declining budgets. Although this effect is harder to quantify, it is clear that the present decision process to build ITER, the next fusion device, conceived as a world-wide venture, could have taken place 10 years ago[23]. Similarly with JET, the existing European device, years were lost in the decision making process even after the machine was designed. Without these delays, we would probably already be running a large scale fusion facility producing very high levels of fusion power, and we would now be discussing the siting of a demonstration power plant.

  Overall then it is possible to estimate the delays introduced into the fusion development programme, in the last 20 years, by the declining budgets and the associated lack of strong decisions to move on to the next stage of R&D. The estimates are given below, although it is perhaps difficult to separate out these two sources of delay since they are coupled together.

Cause of delay
Resulting delay

Declinging budgets
20 years
Decision delays
10-15 years

  It appears then, that there is no imcompatibility between the progress in fusion on the one hand, and the length of the development process. At the same time that progress has been made, the rate of progress has been slowed by a reducing R&D budget. This has a compounding effect of discouraging strong decisions to move on to the next stage. Achieving fusion was brought closer by increased investment prompted by the oil crisis in the 1970's, but during the 1990's the time-scale has been allowed to increase again by reducing funding levels. Although it is difficult to be precise with this analysis, it appears that the way to delay fusion development is to cut the R&D funding—that is not a very surprising result!

December 2002

23   It should be remembered that environmental and security of supply concerns were much less a decade ago, so there was understandably much less pressure then to get on with fusion development and build ITER. Back

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