|Rendering of the ITER machine. The human figure (circled in white) provides a scale. Click to enlarge.|
Ministers from the seven Parties of the international nuclear fusion project ITER (China, European Union, India, Japan, the Republic of Korea, the Russian Federation and the United States of America) today signed the agreement to establish the international organization that will implement the project.
ITER (“the way” in Latin) will be the world’s largest experimental facility to demonstrate the scientific and technical feasibility of fusion power. The construction costs of ITER are estimated at €5 billion (US$6.4 billion) over ten years, most of which will be awarded in the form of contracts to industrial companies and fusion research institutions.
Europe will contribute roughly half of the costs of construction, while the other six parties to this joint international venture (Japan, China, the Republic of Korea, the Russian Federation, India, and the USA), will contribute equally to the rest.
|Two nuclei, here deuterium and tritium, fuse together to form helium, a neutron, and a large amount of energy. Click to enlarge. Source: ITER.|
When the nuclei of light atoms come together at very high temperatures, they fuse and produce enormous amounts of energy. In the core of the sun or a star, the huge gravitational pressure allows this to happen at temperatures of around 10 million degrees Celsius. At the much lower pressures that can be produced on Earth, temperatures to produce fusion need to be much higher—above 100 million degrees Celsius.
To reach these temperatures there must first be powerful heating, and thermal losses must be minimized by keeping the hot fuel particles away from the walls of the container. This is achieved by creating a magnetic cage made by strong magnetic fields, which prevent the particles from escaping. The development of the science and technology involved in this process is the basis of the European fusion program.
The fuel consumption of a fusion power station is projected to be extremely low. A 1 GW fusion plant will need about 100 kg of deuterium and 3 tonnes of natural lithium to operate for a whole year, generating about 7 billion kWh, with no greenhouse gas or other polluting emissions.
To generate the same energy, a coal-fired power plant (without carbon sequestration) requires about 1.5 million tonnes of fuel and produces about 4-5 million tonnes of CO2. The neutrons generated by the fusion reaction cause radioactivity in the materials surrounding the reaction: the walls of the container etc. A careful choice of the materials for these components in future power plants will allow them to be released from regulatory control and possibly recycled about 100 years after the power plant stops operating.
The first meeting of the Interim ITER Council took place at Ministerial level after the signing ceremony. This constituted the first act of the newly established ITER Organization. With the signature of the ITER Agreement and the first Council meeting, the ITER Organization can start its operation on a provisional basis pending the entry into force of the agreement which is expected in the course of 2007.
With the accomplishment of today's meeting, the ITER Organization is able to embark on its mission, as a worldwide international cooperation, to help create a new source of energy for humankind.—ITER Director General Nominee Kaname Ikeda
The international ITER Organization is responsible for and technically oversees all aspects of the project, from application for construction licenses from the nuclear authorities of the host country, through hardware procurements mostly provided in-kind by the Parties, through operation, expected to begin 10 years later and last 20 years, with its involvement of experimental physicists and engineers worldwide, and ultimately for decommissioning of the plant at its end of life.
Upon its entering into force, the ITER Agreement will have a duration initially of 35 years with the possibility of extension for up to 10 years.
Following on from the largest fusion experiments worldwide, ITER’s goal is to provide the know-how to build subsequently the first electricity-generating power station based on magnetic confinement of high temperature plasma.
ITER will test all the main new features needed for that device: high-temperature-tolerant components, large-scale reliable superconducting magnets, fuel-breeding blankets using high temperature coolants suitable for efficient electricity generation, and safe remote handling and disposal of all irradiated components. ITER’s operating conditions are close to those that will be experienced in a power reactor, and will show how they can be optimized, and how hardware design margins can be reduced to increase efficiency and control cost.
In ITER, scientists will study plasmas in conditions similar to those expected in a electricity-generating fusion power plant. It will generate 500 MW of fusion power for extended periods of time, ten times more then the energy input needed to keep the plasma at the right temperature. It will therefore be the first fusion experiment to produce net power. It will also test all the key technologies, including the heating, control, diagnostic and remote maintenance that will be needed for a real fusion power station.
ITER is a tokamak, in which strong magnetic fields confine a torus-shaped fusion plasma. The device’s main aim is to demonstrate prolonged fusion power production in a deuterium-tritium plasma. Compared with current conceptual designs for future fusion power plants, ITER will include most of the necessary technology, but will be of slightly smaller dimensions and will operate at about one-sixth of the power output level, and will not generate electricity.
The programmatic goal of ITER is “to demonstrate the scientific and technological feasibility of fusion power for peaceful purposes.” After extensive discussions with the scientific community at large, this general goal is now interpreted into three specific technical goals, all concerned with developing a viable fusion power reactor.
ITER should produce more power than it consumes. This is expressed in the value of Q, which represents the amount of thermal energy that is generated by the fusion reactions, divided by the amount of external heating. A value of Q smaller than 1 means that more power is needed to heat the plasma than is generated by fusion.
JET, presently the largest tokamak in the world, has reached Q=0.65, near the point of break even (Q=1). ITER has to be able to produce Q=10, or Q larger then 5 when pulses are stretched towards a steady state. This is done so that, in the burning plasma, most of the plasma heating comes from the fusion reactions themselves, and so that the plant efficiency can be sufficiently high to have a chance of leading to an economically viable power plant.
ITER should implement and test the key technologies and processes needed for future fusion power plants: including superconducting magnets, components able to withstand high heat loads, and remote handling.
ITER should test and develop concepts for breeding tritium from lithium-containing materials inside thermally efficient high temperature blankets surrounding the plasma. Tritium self-sufficiency of a fusion power plant is a necessary prerequisite, as tritium is not available in nature.