ITER
Encyclopedia : I : IT : ITE : ITER
ITER is an international tokamak (magnetic confinement fusion) experiment, planned to be built in France and designed to show the scientific and technological feasibility of a full-scale fusion power reactor. It builds upon research conducted on devices such as DIII-D, TFTR, JET, JT-60, and T-15, and will be considerably larger than any of them. The program is anticipated to last for 30 years—10 years for construction, and 20 years of operation—and cost approximately €10 billion ($12.1 billion), making it the second most expensive scientific project after the International Space Station. After many years of deliberation, the participants announced in June 2005 that ITER will be built in Cadarache, France.
According to the ITER consortium, fusion power offers the potential of "environmentally benign, widely applicable and essentially inexhaustible"http://www.iter.org/Benefits.htm Advantages of fusion energy http://newenergytimes.com/PR/FusionAdvantages.htm electricity, properties that they believe will be needed as world energy demands increase while simultaneously greenhouse gas emissions must be reduced,http://www.iter.org/fr3.htm Energy Demand justifying the expensive research project.
ITER is designed to produce approximately 500 MW (500,000,000 watts) of fusion power sustained for up to 500 seconds (compared to JET's peak of 16 MW for less than a second). It is a significant amount of power for a fusion research project; a future fusion power plant would generate about 3000-4000 MW of thermal power. Although ITER will produce net power in the form of heat, the generated heat will not be used to generate any electricity.
ITER was originally an acronym standing for International Thermonuclear Experimental Reactor; that title was dropped to avoid the negative popular connotations of 'thermonuclear' and 'experimental'. 'Iter' also means 'the way' in Latin, and this double meaning reflects ITER's role in harnessing nuclear fusion as a peaceful power source.
ITER is intended to be an experimental step between today's studies of plasma physics and future electricity-producing fusion power plants. It is technically ready to start construction and the first plasma operation is expected in 2016.
![Technical Cutaway of the ITER Tokamak Torus encasing. Published [with permission of ITER.]](http://en.wikipedia.org/wiki/Image:ITER_Tokamak_Cutout.jpg "Technical Cutaway of the ITER Tokamak Torus encasing. Published [with permission of ITER.]")
Objectives
The official objective of ITER is to "demonstrate the scientific and technological feasibility of fusion energy for peaceful purposes". ITER has a number of specific objectives, all concerned with developing a viable fusion power reactor:
- To produce momentarily ten times more thermal energy from fusion heating than is supplied by auxiliary heating (a Q value of 10).
- To produce a steady-state plasma with a Q value of greater than 5.
- To maintain a fusion pulse for up to eight minutes.
- To ignite a 'burning' (self-sustaining) plasma.
- To develop technologies and processes needed for a fusion power plant—including superconducting magnets (pioneered on the Russian T-15) and remote handling (maintenance by robot).
- To verify tritium breeding concepts.
Reactor overview
- See also: nuclear fusion
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All proto and mid-life stars radiate enormous amounts of energy generated by fusion processes. In terms of fuel efficiency, the deuterium-tritium fusion process releases roughly three times as much energy as a uranium 235 fission event, and millions of times more energy than a chemical reaction such as the burning of coal. It is the goal of a fusion power plant to harness this energy to produce electricity.
The activation energy for fusion is so high because the protons in each nucleus will tend to strongly repel one another, as they each have the same positive charge. A heuristic for estimating reaction rates is that nuclei must be able to get within 1 femtometre (1 x 10-15 metre) of each other, where the nuclei are increasingly likely to undergo quantum tunnelling past the electrostatic barrier and the turning point where Strong nuclear force and the electrostatic force are equally balanced, allowing them to fuse. In ITER, this distance of approach is made possible by high temperatures and magnetic confinement. High temperatures give the nuclei enough energy to overcome their electrostatic repulsion (see Maxwell-Boltzmann distribution). For deuterium and tritium, the optimal reaction rates occur at temperatures on the order of 100,000,000 K. The plasma is heated to a high temperature by ohmic heating (running a current through the plasma). Additional heating is applied using neutral beams (which cross magnetic field lines without a net deflection and will not cause a large electromagnetic distruption) and radio-frequency (RF) or microwave heating.
At such high temperatures, particles have a vast kinetic energy, and hence velocity. If unconfined, the particles will rapidly escape, taking the energy with them, cooling the plasma to the point where net energy is no longer produced. A successful reactor would need to contain the particles in a small enough volume for long enough for much of the plasma to fuse. In ITER and many other magnetic confinement reactors, the plasma, a gas of charged particles, is confined using magnetic fields. A charged particle, when crossing a magnetic field, does not escape if left unperturbed. It simply spins around the magnetic field, in Larmor gyrorotation. The particle may move along the magnetic field unopposed by the field, but if the field is wrapped into a toroidal or doughnut shape, it is then confined.
A solid confinement vessel is also needed, both to shield the magnets and other equipment from high temperatures and energetic photons and particles, and to maintain a near-vacuum for the plasma to populate. The containment vessel is subjected to a barrage of very energetic particles, where electrons, ions, photons, alpha particles, and neutrons constantly bombard the surface and degrade the structure. The material must be designed to stand-up to this environment for long enough so that an entire powerplant would be economical. Tests of such materials will be carried out both at ITER and at IFMIF(International Fusion Materials Irradiation Facility).
Once fusion has begun, high energy neutrons will radiate from the reactive regions of the plasma, crossing magnetic field lines easily due to charge neutrality (see neutron flux). Since it is the neutrons that receive the majority of the energy, they will be ITER's primary source of energy output. Ideally, alpha particles will expend their energy in the plasma, further heating it.
Beyond the inner wall of the containment vessel one of several test blanket modules are to be placed. These modules are designed to slow and absorb neutrons in a reliable and efficient manner, limiting damage to the rest of the structure, and breeding tritium from lithium and the incoming neutrons for fuel. Energy absorbed from the fast neutrons is extracted and passed onto the primary coolant. This energy would then be used to power an electricity generating turbine in a real power plant, however in ITER this is not of scientific interest, and will simply be released.
History
ITER began in 1985 as a collaboration between the European Union (through EURATOM), the USA, the then Soviet Union and Japan. Conceptual and engineering design phases led to an acceptable, detailed design in 2001, underpinned by $650 million worth of research and development by the "ITER Parties" to establish its practical feasibility. These parties (with the Russian Federation replacing the Soviet Union and with the USA opting out of the project in 1999 and returning in 2003) were joined in negotiations on the future construction, operation and decommissioning of ITER by Canada (who then terminated their participation at the end of 2003), the People's Republic of China, and the Republic of Korea. India officially became part of ITER on December 6, 2005. The project is expected to cost about €10 billion ($12.1 billion) over its thirty year life.
On June 28, 2005 it was officially announced that ITER will be built in the European Union, in Southern France. The negotiations that led to the decision ended in a compromise between the EU and Japan, in that Japan was promised 20 percent of the research staff on the French location of ITER as well as the head of the administrative body of ITER. In addition another research facility for the project will be built in Japan and the European Union has agreed to contribute about 50% of the costs of this institution.http://www.asahi.com/english/Herald-asahi/TKY200506280351.html
ITER will run in parallel with a materials test facility, the International Fusion Materials Irradiation Facility (IFMIF), which will develop materials suitable for use in the extreme conditions that will be found in future fusion power plants. Both of these will be followed by a demonstration power plant, DEMO, which would generate electricity. DEMO would be the first to produce electric energy for commercial use.
Location
The process of selecting a location for ITER was long and drawn out. The most likely sites were Cadarache in Provence-Alpes-Côte-d'Azur, France and Rokkasho, Aomori, Japan. Additionally, Canada announced a bid for the site in Clarington in May 2001, but withdrew from the race in 2003. Spain also offered a site at Vandellos on April 17, 2002, but the EU decided to concentrate its support solely behind the French site in late November 2003. From this point on the choice was between France and Japan. On May 3 2005, the EU and Japan agreed to a process which would settle their dispute by July.
At the final meeting in Moscow on June 28, 2005 the participating parties agreed on the site in Cadarache in Provence-Alpes-Côte-d'Azur, France.
Construction of the ITER complex is planned to begin in 2008,http://www.iter.org/pics/constructionschedule.pdf while assembly of the tokamak itself is scheduled to begin in the year 2011. These dates are guides only however, and one could reasonably expect political, financial or even social issues to alter them substantially.
Participants
Currently there are seven national and supranational parties participating in the ITER program: the European Union, USA, Japan, Russia, India, China and South Korea. http://www.spacewar.com/news/nuclear-civil-05zzzx.html Members of the ITERFunding
As it stands now the proposed costs are €10 billion ($12.1 billion) for the construction of ITER, its maintenance and the research connected with it during its lifetime. At the June 2005 conference in Moscow the participating members of the ITER cooperation agreed on the following division of funding contributions: 50% by the hosting member, the European Union and 10% by each non-hosting member. http://www.itercad.org/pr_ministers_jun05.html According to sources at the ITER meeting at Jeju, Korea, the six non-host partners will now contribute 6/11th of the total cost - a little over half - while E.U. will put in the rest. As for the industrial contribution, China, India, Korea, Russia and the U.S. will contribute 1/11th each, Japan 2/11th and Europe 4/11th.http://www.flonnet.com/fl2301/stories/20060127003709900.htm A nuclear leap, Frontline, Vol 23, Iss 1, (Jan. 14 - 27, 2006)Note that although Japan's financial contribution as a non-hosting member is 1/11 of the total, the EU agreed to grant it a special status so that Japan will provide for 2/11 of the research staff at Cadarache and be awarded 2/11 of the construction contracts, while the European Union's staff and construction components contributions will be cut from 5/11 to 4/11.
Criticism
The project experienced large opposition from environmental groups such as Greenpeace. "Pursuing nuclear fusion and the ITER project is madness," said Bridget Woodman of Greenpeace. "Nuclear fusion has all the problems of nuclear power, including producing nuclear waste and the risks of a nuclear accident."http://www.eubusiness.com/press/EUPress.2003-11-26.3159 "Governments should not waste our money on a dangerous toy which will never deliver any useful energy," said Jan Vande Putte of Greenpeace International. "Instead, they should invest in renewable energy which is abundantly available, not in 2080 but today".http://www.greenpeace.org/international/press/releases/ITERprojectFranceFrench environmental groups slammed the project ITER, saying it was "dangerous", "costly", and "not a job generator". A French association including about 700 anti-nuclear groups, Sortir du nucléaire (Get Out of Nuclear Energy), also claimed that ITER was a hazard because scientists did not yet know how to manipulate the high-energy deuterium and tritium hydrogen isotopes used in the fusion process.http://www.dw-world.de/dw/article/0,1564,1631650,00.html
As of 2005, many scientists believe that the ITER project confronts numerous technically challenging issues. Pierre-Gilles de Gennes, French Nobel laureate in Physics (awarded the Prize for work unrelated to plasma or high-energy physics), is well known for saying "We say that we will put the sun into a box. The idea is pretty. The problem is, we don't know how to make the box". The box is a simplification of the general magnetic confinement fusion scheme in which a high energy ionized gas (a plasma) is confined in a magnetic field. The plasma and the magnetic field is then enclosed in a material structure which would be designed to handle the enormous temperatures, magnetic pressures, and particle fluxes from the hot confined plasma. ITER's first wall will be made of beryllium and tungsten, and its concrete containment structure will be designed to resist radioactive activation, similar to those used for fission reactors.
Masatoshi Koshiba, Japanese winner of a Nobel Prize in Physics expanded on the idea, stating that "Inside ITER, the fusion reaction produces high energy neutrons, of 14 MeV [...] Although scientists have already experienced the manipulation of low energy neutrons, these 14 MeV neutrons are totally new and at the present time, nobody knows how to manipulate them". When extremely energetic neutrons collide with material, such as the housing of the reactor, they have the propensity to cause energetic secondary radiation and greatly damage crystalline structures in solids. Furthermore, once the neutrons have slowed they can become captured by the nuclei of atoms, potentially 'activating' them, transforming them into radioactive isotopes. The activation risk is shared with fission power plants (but of a much lower magnitude), although the fusion process will not produce any of the long-lived radionuclides associated with fission. Also, it will be harder to control because the energetic neutrons will escape much further from the reactive core, on average, than low energy neutrons.
Voicing opposition to the project was Rebecca Harms, Green/EFA member of the European Parliament's Committee on Industry, Research and Energy, who said: "In the next 50 years nuclear fusion will neither tackle climate change nor guarantee the security of our energy supply." Arguing that the EU's energy research should be focused elsewhere, she said: "The Green/EFA group demands that these funds be spent instead on energy research that is relevant to the future. A major focus should now be put on renewable sources of energy." French Green party lawmaker Noël Mamère claims that more concrete efforts to fight present-day global warming will be neglected as a result of ITER: "This is not good news for the fight against the greenhouse effect because we're going to put ten billion euro towards a project that has a term of 30-50 years when we're not even sure it will be effective."http://www.euractiv.com/Article?tcmuri=tcm:29-141693-16&type=News
Response to criticism
Proponents believe that much of the ITER criticism is misleading and uneducated, in particular the allegations of the experiment's "inherent danger". The stated goals for a commercial fusion power station design are that the amount of radioactive waste produced will be hundreds of times less than that of a fission reactor, that it will produce no long-lived radioactive waste, and that it will be impossible for any fusion reactor to undergo a large-scale runaway chain reaction. This is because the amount of fuel planned to be contained in a fusion reactor chamber (half a gram of deuterium/tritium fuelhttp://www.iter.org/a/index_nav_2.htm (follow "why fusion power?" >> "safety")) is only enough to sustain the reaction for about a minute, whereas a fission reactor contains about a year's supply of fuel (100 tons of uranium and plutonium). Proponents note that large-scale fusion power - if it works - will be able to produce reliable electricity on demand and with virtually zero pollution (zero gaseous CO2 / SO2 / NOx by-products are made).Experts say that many reasonable estimates place the generation of electricity from fusion on a plant scale in the 2030s.http://www.iop.org/EJ/abstract/0029-5515/45/2/004 Nucl. Fusion 45 (2005) 96–109 "Demonstration tokamak fusion power plant for early realization of net electric power generation" These estimates are based on detailed knowledge of the areas in which advances need to be made, particularly in materials research for the plasma-facing components, and it would take an overly pessimistic estimate to overstate the measured expert guess by fifty years.
The cost of any scientific or engineering project must be weighed carefully against its possible benefit. In the United States alone, electricity accounts for $210 Billion in annual sales.http://www.eia.doe.gov/cneaf/electricity/chg_str_fuel/html/frontintr.html Asia's electricity sector attracted $93 billion in private investment between 1990 and 1999.http://www.findarticles.com/p/articles/mi_qa3650/is_200207/ai_n9093799 It should be pointed out that these figures take into account only current prices. With petroleum prices slated to rise, political pressure on carbon production, and steadily increasing demand, these figures will necessarily rise. An investment in research now should be viewed as an attempt to earn a far greater future return for the economy.
The assertion that ITER is "not a job generator" is both false and would not constitute a fair argument even if it were true. ITER will provide employment for hundreds of physicists, engineers, material scientists, construction workers and technicians in the short term, and likely thousands of power plant operators in the long term (as part of the global fusion effort). Whether it does or not, however, should not have a bearing on whether it is a worthwhile scientific investment, given the inestimable benefits that would accrue to humankind (and the planet) if fusion power could be harnessed for peaceful purposes.
Handling the energetic neutron flux is one of the primary missions of ITER, and the only reasonable experiment to test ideas for handling the intense neutron flux is to create a burning plasma. The purpose of ITER is to explore the scientific and engineering questions surrounding fusion power plants, such that it may be possible to build one intelligently in the future. It is nearly impossible to get satisfactory theoretical results regarding the properties of materials under an intense energetic neutron flux, and burning plasmas are expected to have quite different properties from externally heated plasmas. The point has been reached where answering these questions about fusion reactors by experiment (ITER) is an economical research investment, given the monumental potential benefit.
Many environmentalists who endorse ITER and fusion projects feel frustrated and isolated by comments such as "In the next 50 years nuclear fusion will neither tackle climate change nor guarantee the security of our energy supply". Worst among misgivings is the certainty implicit in such statements. If and when fusion is finally made commercially viable, the greenhouse gas emissions problem will be entirely reduced to an energy storage and transfer problem, as power generation will be done in a greenhouse gas-free manner. Whether this happens twenty, thirty, fifty, or a hundred years from now does not significantly affect whether or not pursuing it is worthwhile, because only fusion and fission power would be sufficient for projected demand. If renewables were supported while fusion and fission were not, the remaining power demand would have to be obtained from conventional power sources, further worsening climate change. Furthermore, renewable sources of energy often have environmental issues of their own (such as wind power or water power) and the power output of such installations is often ignored when compared to conventional sources of energy. For example large wind turbines can produce up to 5MW whereas a large fossil or nuclear fuelled power station can continuously produce 200-300 times that amount. Once fusion is available and widespread, there will be no natural fluctuations in the energy supply, because there will be no significant fuel bottleneck: a large component of future fusion-reactor fuel can be extracted from seawater.
External links
- [ITER home page], includes pictures and diagrams available to use for educational purposes
- [French Government ITER page]
- [CEA ITER page]
- [Commission particulière du débat public Projet ITER (French site)]
- [ITER Technical Objectives]
- [EFDA home page]
- [FIRE home page], with current news on ITER and other burning plasma developments
- [IFMIF home page].
- [Fusion Energy Educational Web Site] of the Princeton Plasma Physics Laboratory
- [The Fast Track To Fusion Power] by Chris Llewellyn Smith of the UK Atomic Energy Agency
- [Climate Change Chronicles article about France winning the ITER contract]
- [ITER and ORNL]
- [Reuters News Agency]
- [Fusion reactors explained by HowStuffWorks]
- [Unofficial ITER fan club]
Critical websites
- [Against ITER (French site)]
- [New Energy Times] Online news magazine with an emphasis on cold fusion
References
[[zh-min-nan:Kok-chè Jia̍t-hu̍t-chú Si̍t-giām Hoán-èng-lô·]]
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