Would it be Japan or Europe? Few scientific events attract the media attention that surrounded the announcement, in 2005, of the international agreement on the construction of the International Thermonuclear Experimental Reactor – otherwise known as ITER. On the day, the final choice was the Cadarache site, in France, which had been the European Union’s preference. A public debate is now being launched in the region to present the project as the international scientific teams come together and the seven project partners put the finishing touches to the project. All in all, this is the ideal moment to take a look at the progress of operations and the scientific and technological challenges ITER will be facing.
The ITER construction site in Cadarache
In the face of the inevitable increase in global electricity demand between now and the latter half or end of the 21st century, the importance for society of mastering the industrial techniques of nuclear fusion are well known. After 20 years of reflection, the project to build the International Thermonuclear Experimental Reactor – better known as ITER – has now entered its implementation phase, bringing with it the promise of a solution.
Possessing none of the drawbacks in terms of fossil fuel consumption, greenhouse gas emissions, danger of explosion, production of radioactive waste that must be stored or of fissile material that could proliferate, this potential energy source could offer a genuine revolution in the face of a looming energy crisis. The world population is continuing to grow inexorably towards the 9 billion mark and it will not be possible to meet the energy needs of these individuals either through recourse to renewable energy sources alone or through fossil fuels, which are too polluting and will be exhausted sooner or later, in any event.
Prototypes of the central and toroidal superconducting components that ensure plasma confinement.
Providing a solution to the problem now is an obligation towards future generations that is incumbent not just upon science, but also upon contemporary society as a whole. The response has been an unprecedented international mobilisation in the form of a total investment of €10 billion over 40 years and an international organisation bringing together the European Union, Japan, the United States, South Korea, Russia, China and India.
The partners are currently finalising agreements on the sharing of costs (see box) and putting into place the ITER international organisation that will build and operate the device. A treaty is due to be signed later this year that must then be ratified by each of the partners before it enters into force. The organisation of a public debate (see A new exercise in technical democracy) in the region of the ITER construction site is also required under French legislation before the final green light can be given.
A complex exercise in assembly As the negotiations enter the final stages, the provisional international organisation – currently headed by Kaname Ikeda of Japan and based in Garching (Germany), Naka (Japan) and Cadarache (France) – is putting the finishing touches to the ITER technical specifications and its installation at the selected site. Akko Maas, a Dutch researcher and member of the team, explains that “the contribution of each of the partners is essentially a contribution in kind, in the form of subsystems supplied to the international team that then assembles them to create ITER”. This construction process will last several years, from the casting of the initial concrete in 2008/2009 to start-up in 2016. Akko Maas gives some idea of the scale of the project: “The quantity of cables needed to produce the superconducting coils is equivalent to the global annual production of this type of element.”
For Europe, a joint company is to be set up with its headquarters in Barcelona. Serge Paidassi of the European Commission’s Research Directorate-General explains: “The joint company will have the principal task of managing the European contribution to the ITER international organisation. Calls for tenders will be issued to European industry to supply the major components.”
Uniting the ‘big brothers’ The purpose of the ITER tokamak, a reactor in the form of a torus, is to produce, for the first time anywhere in the world, a magnetically confined fusion plasma that is self-sustaining and stable, thereby validating fusion as a potential energy source. The scientific and technological knowledge needed for its construction is based on patient research programmes carried out over the past three decades, with the support of the EU in particular.
With JET (Joint European Torus), which has been in service in the UK since 1983, the scientific community mastered the technique of fusion reactions within a plasma in the form of an ionised gas maintained at a temperature of over 100 million degrees. This plasma consists of a mixture of two kinds of hydrogen: deuterium – the component of ‘heavy water’ – and radioactive tritium, obtained from lithium.
Other experimental installations in Europe have contributed to the excellence of European research in the field of fusion: Tore Supra in France is the first large tokamak which uses superconductive magnets in plasmas of high energy and long duration. ASDEX Upgrade in Germany works with plasmas of the same form as ITER and highlighted modes of plasma containment which will be studied at ITER. FTU in Italy studies the intense magnetic fields, while the potential of spherical tokamaks is being studied in the United Kingdom at MAST. Stellarators, an alternative to the tokamaks, are being studied in Germany with the construction of W7-X and TJII in Spain. The results of the research undertaken in the European programme, combined with the contribution of the other international partners, provides the confidence and the expertise necessary to begin the construction of ITER and to take the next decisive step towards fusion energy.
One of ITER’s innovations is the way it is bringing together the technologies of its ‘big brothers’ within a single facility. “The international scientific community considered that the time had come to stop research on any one fusion parameter using specialised devices and to bring together all the constraints within a single machine. ITER is the necessary step to make this transition in a minimum of time and to prepare for the next stage, that is, an industrial tool rather than a scientific tool – that has already been given the name ‘DEMO’”, confirms Michel Chatelier, Head of the Fusion Department at the French Atomic Energy Commissariat (CEA).
The crucial coefficient of one
Cut-away of the ITER reactor.
ITER represents a major qualitative advance. It increases the power amplification coefficient – that is, the ratio between the energy needed to maintain the fusion conditions and the energy produced by the reaction – in favour of the latter. The fusion of the deuterium and tritium nuclei produces alpha particles (helium nuclei), neutrons and 17.6 MV of energy. The neutrons, which contain 80% of this energy, escape from the reactor core and subsequently make it possible to produce electricity. But the fusion only takes place if the environment is maintained at a sufficiently hot temperature and confined magnetically by means of energy-sapping devices. The operation only becomes profitable from the moment the plasma becomes self-sustaining, that is, when the energy transmitted to the plasma by the alpha particles produced at the time of the reaction participates in maintaining its temperature.
No device has yet achieved this performance. The record is held by JET, which achieved a fusion peak of 16 MW during one second in 1997, with a power amplification of 0.64. This is still considerably short of the crucial coefficient of one! To produce such a plasma, this critical threshold must be reached. Chatelier picks up the story: “In terms of volume, ITER is eight times bigger than today’s machines. The scientific goal is to produce ten times more power than will be necessary for its own heating, which means producing 500 MW of thermal power for 50 MW of heating power. And this on a time scale of 400 seconds that is seen as necessary for the scientific demonstration.”
Challenges and unknown factors
Prototypes of the central and toroidal superconducting components that ensure plasma confinement.
But how does steady-state plasma behave? It is only post-ITER that we will have the answer. Serge Paidassi stresses that ITER “will also be the first machine in which such plasma will last a sufficient length of time to know what effect the build-up of helium in the deuterium-tritium mix will have. We will have to see how to evacuate the ash produced by the fusion reaction with the diverter, a device located at the base of the facility. ITER is an essential tool for testing a fusion energy plasma under real conditions.”
The other major unknown factor that must be learned before a nuclear fusion reactor can be produced on an industrial scale is the behaviour of the materials that constitute its shell. These are severely tested by the fusion temperature and radiation. ITER will be used to test the materials that come into direct contact with the plasma, as well as the tritigenous blankets. Placed around the reactor and bombarded with the high-energy neutron flows coming from the shell, these will contain lithium, from which the radioactive tritium that fuels the reactor will be produced.
ITER cannot be a prototype reactor supplying electricity or function over long periods as the materials used in its construction are not yet low activation. According to Serge Paidassi: “The European joint company must also manage the fusion technology programme that we are going to initiate to prepare for the post-ITER stage and the construction of the Demo demonstration reactor. For that, we must develop a testing plant (International Fusion Materials Irradiation Facility – IFMIF) for the 14 MeV neutron flows to check their behaviour when subjected to prolonged periods of radiation. Europe will work on this in partnership with the Japanese. This is one of the projects within the broader approach.”
The ITER operating stage is scheduled to last for 20 years, until it is dismantled in around 2040. The creation of Demo, the prototype fusion reactor that actually produces electricity, will then be the next technological challenge facing the international scientific community. While the Promethean dream of harnessing the Sun’s energy remains a distant prospect for humankind, ITER (which owes its name to the Latin iter, meaning ‘way’) aims to be one of the avenues through which this is ultimately achieved.
The cost of ITER
The total cost of ITER is shared between the seven project partners, with 50% falling to the European Union, which is responsible for costs linked to installation, and around 10% for each of the other participants. These figures are the admission ticket to the organisation. They provide the basis for ...
A new exercise in technical democracy
Avignon, February 2006. "The layperson is perfectly entitled to speak about the implications and aims of scientific projects. All contributions are legitimate, provided they respect the rules of dialogue and are well reasoned,” announced Patrick Legrand, President of the ITER Commission particulière ...
The total cost of ITER is shared between the seven project partners, with 50% falling to the European Union, which is responsible for costs linked to installation, and around 10% for each of the other participants. These figures are the admission ticket to the organisation. They provide the basis for international negotiations, but are subject to change as minority partners (such as Brazil, Argentina or Canada) could contribute to the project at a later date. Most of the contributions will be in the form of the supply of subsystems, provided by agencies located in each country. The EU’s agency will be based in Barcelona (ES).
A new exercise in technical democracy
Avignon, February 2006. "The layperson is perfectly entitled to speak about the implications and aims of scientific projects. All contributions are legitimate, provided they respect the rules of dialogue and are well reasoned,” announced Patrick Legrand, President of the ITER Commission particulière du débat public (CPDP) in Provence. RTD info reports on a citizen’s debate held in a town located less than ten kilometres from the Cadarache site.
About 80 people were present on the day for the debate held in Avignon. The aim of the organisers was to encourage dialogue between the scientific community responsible for the project, members of the public, elected representatives and associations. It was just one of a series of debates planned through to the month of May. Two debates had already been held, at which the militancy of associations opposed to the ITER project somewhat upset the proceedings. The Avignon debate proved to be a much calmer affair. After a presentation of the project by Michel Chatelier, Head of the Fusion Department at the Atomic Energy Commission (CEA)/Cadarache, it was time for questions. Will ITER stimulate the regional economy? What impact will building and operating the facility have on the environment? Is there any risk of radioactive emissions? Are the expected scientific results realistic? Is fusion the miracle cure? Should the emphasis not be placed on renewable energies? Why is the scientific community divided on whether or not to build ITER?
"The public debate can provide the opportunity to discuss ITER’s goals and the energy option nuclear fusion represents. ITER is about building a device, but it is also an institution in the making and involves relationships between the international research, technological and operating structures that are being set up. The facility is not just a technical device, it is a socio-technical object,” explains Legrand.
The architects of ITER, including representatives of the French Government, the European Commission and the CEA as spokesperson for the partners, came to defend the project and explain its scientific, economic and social dimensions. Eisuke Tada of Japan, Director of the international team at Cadarache, was also present at the debate. Team member Akko Maas, a Dutch researcher, spoke on behalf of foreign scientists who will be working at Cadarache: “We are here to hear what the local people think of ITER and how they see its implantation in their environment and to learn of their fears and their expectations. We do not want to impose anything. We want to set up in the region and live as good neighbours with the local population.”
The coexistence of different cultures (20% of ITER workers will be Japanese) is an aspect of the project that had received little attention prior to this meeting. “This public debate is about the social acceptability and utility of the ITER project,” continued Legrand. “When it comes to major projects of this kind we see two legitimacies come into conflict: that of the major geostrategic treaties of the Euratom variety and another legitimacy born of the notion of good governance that originated at the UN Conference in Rio. These are two different geopolitical masses that are coming together.”
The public debate is no doubt the least scientific of the events planned by ITER and constitutes a new exercise in ‘technical democracy’ that has been incorporated in French legislation since 2002. According to sociologist Michel Callon,(1) "because they shape a treble inventory, that of the stakeholders, the problems and the solutions, controversies are a very effective way of exploring possible worlds in a situation of uncertainty.”
(1) Michel Callon, Pierre Lascoumes, Yannick Barthe, Agir dans un monde incertain. Essai sur la démocratie technique, Paris, Le Seuil, 2001.