ITER

Coordinates: 43°42′30″N 5°46′39″E / 43.70831°N 5.77741°E / 43.70831; 5.77741

ITER

Eight participating members
Formation	24 October 2007
Headquarters	Saint-Paul-lès-Durance, France
Membership	China  European Union  India  Japan  Russia  South Korea  United States Others:  Australia  Canada  Kazakhstan  Thailand  United Kingdom (under the EU's Fusion for Energy)   Switzerland (as member of EURATOM)
Director-General	Bernard Bigot
Website	www.iter.org

ITER

Small-scale model of ITER
Device type	Tokamak
Location	Saint-Paul-lès-Durance, France
Technical specifications
Major radius	6.2 m (20 ft)
Plasma volume	840 m3
Magnetic field	11.8 T (peak toroidal field on coil) 5.3 T (toroidal field on axis) 6 T (peak poloidal field on coil)
Heating power	50 MW
Fusion power	500 MW
Discharge duration	up to 1000 s
History
Date(s) of construction	2013 – 2025

ITER (initially the International Thermonuclear Experimental Reactor, "iter" meaning "the way" or "the path" in Latin^[1][2][3]) is an international nuclear fusion research and engineering megaproject aimed at replicating the fusion processes of the Sun to create energy on earth. Upon completion of construction and first plasma, planned for late 2025,^[4] it will be the world's largest magnetic confinement plasma physics experiment and the largest experimental tokamak nuclear fusion reactor, which is being built next to the Cadarache facility in southern France.^[5][6] ITER will be the largest of more than 100 fusion reactors built since the 1950s, with ten times the plasma volume of any other tokamak operating today.^[7][8]

The purpose of ITER is to demonstrate the scientific and technological feasibility of fusion energy for future electricity generation.^[9][7] ITERs goals are: to achieve enough fusion to produce 10 times as much output power as input for short time periods; to demonstrate and test technologies that would be needed to operate a fusion power plant including cryogenics, heating, control, and diagnostics systems, including remote maintenance; to achieve and learn from a burning plasma; to test tritium breeding; and to demonstrate the safety of a fusion plant.^[8][6]

ITER's thermonuclear fusion reactor will attempt to use 50 MW of heating power to create a plasma of 500 MW (thermal) for periods of 400 to 600 seconds.^[10] This would mean a ten-fold gain of plasma heating power or, as measured by heating input to thermal output, Q ≥ 10.^[11] The current record for energy production using nuclear fusion is held by the Joint European Torus reactor, which injected 24 MW of heating power to create a 16 MW plasma, for a Q of 0.67, in 1997.^[12] Beyond just heating the plasma, the total electricity consumed by the reactor and facilities will range from 110 MW up to 620 MW peak for 30-second periods during plasma operation.^[13] As a research reactor, the heat energy generated will not be converted to electricity, but simply vented.^[6][14][15]

ITER is funded and run by seven member parties: the European Union, China, India, Japan, Russia, South Korea, and the United States; the United Kingdom and Switzerland participate through Euratom, while the project has cooperation agreements with Australia, Kazakhstan, and Canada.^[16]

Construction of the ITER complex started in 2013,^[17] and assembly of the tokamak began in 2020.^[18] The initial budget was close to €6 billion, but the total price of construction and operations is projected to be €18 to €22 billion;^[19][20] other estimates place the total cost between $45 billion and $65 billion, though these figures are disputed by ITER.^[21][22] Regardless of the final cost, ITER has already been described as the most expensive science experiment of all time,^[23] the most complicated engineering project in human history,^[24] and one of the most ambitious human collaborations since the development of the International Space Station (€100 billion budget) and the Large Hadron Collider (€7.5 billion budget).^[25][26]

ITER's planned successor, the EUROfusion-led DEMO, is expected to be one of the first fusion reactors to produce electricity in an experimental environment.^[27]

Background[]

ITER will produce energy by fusing deuterium and tritium to helium.

Fusion power has the potential to provide sufficient energy to satisfy mounting demand, and to do so sustainably, with a relatively small impact on the environment. One gram of deuterium-tritium mixture in the process of nuclear fusion produces an amount of energy equivalent to burning eight tonnes of oil.^[28]

Nuclear fusion uses a different approach to traditional nuclear energy. Current nuclear power stations rely on nuclear fission with the nucleus of an atom being split to release energy. Nuclear fusion takes multiple nuclei and uses intense heat to fuse them together, a process that also releases energy.^[29]

Fusion aims to replicate the process that takes place in stars where the intense heat at the core fuses together nuclei and produces massive amounts of energy in the form of heat and light. Harnessing fusion power in terrestrial conditions would provide sufficient energy to satisfy mounting demand, and to do so in a sustainable manner that has a relatively small impact on the environment. One gram of deuterium-tritium fuel mixture in the process of nuclear fusion produces 90,000-kilowatt hours of energy, or the equivalent of 11 tonnes of coal.^[30]

Nuclear fusion has many potential attractions. The fuel is relatively abundant or can be produced in a fusion reactor. After preliminary tests with deuterium, ITER will use a mix of deuterium-tritium for its fusion because of the combination's high energy potential.^[31] The first isotope, deuterium, can be extracted from seawater, which means it is a nearly inexhaustible resource.^[32] The second isotope, tritium, only occurs in trace amounts in nature and the estimated world's supply (mainly produced by the heavy-water CANDU fission reactors) is just 20 kilograms per year, insufficient for power plants.^[33] ITER will be testing tritium breeding blanket technology that would allow a future fusion reactor to create its own tritium and thus be self-sufficient.^[34][35] Furthermore, a fusion reactor would produce virtually no CO₂ emissions or atmospheric pollutants, there would be no chance of a meltdown, and its radioactive waste products would mostly be very short-lived compared to those produced by conventional nuclear reactors (fission reactors).^[36]

On 21 November 2006, the seven project partners formally agreed to fund the creation of a nuclear fusion reactor.^[37] The program is anticipated to last for 30 years – 10 years for construction, and 20 years of operation. ITER was originally expected to cost approximately €5 billion.^[38] However, delays, the rising price of raw materials, and changes to the initial design have seen the official budget estimate rise to between €18 billion and €20 billion.^[39][40]

The reactor was expected to take 10 years to build and ITER had planned to test its first plasma in 2020 and achieve full fusion by 2023, however the schedule is now to test first plasma in 2025 and full fusion in 2035.^[41] Site preparation has begun in Cadarache, France, and French President Emmanuel Macron launched the assembly phase of the project at a ceremony in 2020.^[42] Under the revised schedule, work to achieve the first hydrogen plasma discharge is now 70% complete and considered on track.^[43]

When the fusion experiments begin, the stated objective of ITER is to become the first fusion device to produce net energy.^[44] The official calculations state that 50MW of heating power will be injected into the plasma to create fusion power of 500MW for 400-second pulses. With nuclear fusion, the fusion energy gain factor is expressed with the symbol Q, where Q = 1 is a breakeven situation. This means that ITER's goal is to achieve a minimum fusion energy of Q=10. This compares to the current fusion record achieved by JET's when it injected 24MW of heating energy to create a fusion energy output of 16 MW, which meant a Q of 0,67.^[45]

However, there is an alternative calculation for fusion energy, the 'engineering' Q that takes into account all of the energy required to operate the fusion reactor and not just the energy used to heat the plasma. As explained in the book ITER: The Giant Fusion Reactor, written by former ITER communication director Michel Claessens, 'some observers have calculated that ITER will use 300 MW of electrical power to produce the equivalent of 500 MW of thermal power, or an engineering Q of 1,6. (Using the engineering Q, JET's total energy consumption was 700 MW of electrical power to create a peak thermal output of 16 MW.)^[6]

ITER will not produce enough heat to produce net electricity and therefore is not equipped with turbines to generate electricity. Instead, the heat produced by the fusion reactions will be vented. The DEMO-class reactors that follow ITER are intended to demonstrate the net production of electricity.^[46] Because of inefficiencies in generating electricity and other factors, some nuclear engineers consider a Q of 100 – a hundred-fold energy output – is required for commercial fusion power stations to be viable.^[47]

Organisation history[]

Ronald Reagan and Mikhail Gorbachev at the Geneva Summit in 1985

The initial international cooperation for a nuclear fusion project that was the foundation of ITER began in 1979 with the International Tokamak Reactor, or INTOR, which had four partners: the Soviet Union, the European Atomic Energy Community, the United States, and Japan. However, the INTOR project stalled until Mikhail Gorbachev became general secretary of the Communist Party of the Soviet Union in March 1985. Gorbachev first revived interest in a collaborative fusion project in an October 1985 meeting with French President François Mitterrand, and then the idea was further developed in November 1985 at the Geneva Summit with Ronald Reagan.^[48][49][50]

Preparations for the Gorbachev-Reagan summit showed that there were no tangible agreements in the works for the summit. However, the ITER project was gaining momentum in political circles due to the quiet work being by two physicists, the American scientist Alvin Trivelpiece who served as Director of the Office of Energy Research in the 1980s and the Russian scientist Evgeny Velikhov who would become head of the Kurchatov Institute for nuclear research. The two scientists both supported a project to construct a demonstration fusion reactor. At the time, magnetic fusion research was ongoing in Japan, Europe, the Soviet Union and the US, but Trivelpiece and Velikhov believed that taking the next step in fusion research would be beyond the budget of any of the key nations and that collaboration would be useful internationally.^[51]

Dr. Michael Robert, who is the director of International Programs of the Office of Fusion Energy at the US Department of Energy, explains that, 'In September 1985, I led a US science team to Moscow as part of our bilateral fusion activities. Velikhov proposed to me at lunch one day his idea of having the USSR and USA work together to proceed to a fusion reactor. My response was 'great idea', but from my position, I have no capability of pushing that idea upward to the President.' ^[52]

This push for cooperation on nuclear fusion is cited as a key moment of science diplomacy, but nonetheless a major bureaucratic fight erupted in the US government over the project. One argument against collaboration was that the Soviets would use it to steal US technology and expertise. A second was symbolic and involved American criticism of how the Soviet physicist Andrei Sakharov was being treated. Sakharov was an early proponent of the peaceful use of nuclear technology and along with Igor Tamm he developed the idea for the tokamak that is at the heart of nuclear fusion research.^[53] However, Sakharov also supported broader civil liberties in the Soviet Union, and his activism earned him both the 1975 Nobel peace prize and internal exile in Russia, which he opposed by going on multiple hunger strikes.^[54] The United States National Security Council convened a meeting under the direction of William Flynn Martin to discuss the nuclear fusion project that resulted in a consensus that the US should go forward with the project.

This led to nuclear fusion cooperation begin discussed at the Geneva summit and release of a historic joint statement from Reagan and Gorbachev that emphasized, "the potential importance of the work aimed at utilizing controlled thermonuclear fusion for peaceful purposes and, in this connection, advocated the widest practicable development of international cooperation in obtaining this source of energy, which is essentially inexhaustible, for the benefit of all mankind."^[55][56] For the fusion community, this statement was a breakthrough, and it was reinforced when Reagan evoked the possibilities of nuclear fusion in a Joint Session of Congress later in the month.^[52]

As a result, collaboration on an international fusion experiment began to move forward. In October 1986 at the Reykjavik Summit, the so-called 'Quadripartite Initiative Committee' (Europe through the Euratom countries, Japan, USSR, and the USA) was formed to oversee the development of the project.^[57] The year after, in March 1987, the Quadripartite Initiative Committee met at the International Atomic Energy Agency (IAEA) headquarters in Vienna. This meeting marked the launch of the conceptual design studies for the experimental reactors as well the start of negotiations for operational issues such as the legal foundations for the peaceful use of fusion technology, the organizational structure and staffing, and the eventual location for the project. This meeting in Vienna was also where the project was baptized the International Thermonuclear Experimental Reactor, although it was quickly referred to by its abbreviation alone and its Latin meaning of 'the way'.^[52]

Conceptual and engineering design phases were carried out under the auspices of the IAEA.^[58] The original technical objectives were established in 1992 and the original Engineering Design Activities (EDA) were completed in 1998.^[59] An acceptable, detailed design was validated in July 2001 to complete the extended EDA period, and the validated design then went through a Design Review that began November 2006 and concluded in December 2007.^[60][61] The design process was difficult with arguments over issues such as whether there should be circular cross sections for magnetic confinement or 'D' shaped cross sections. These issues were partly responsible for the United States temporarily exiting the project in 1999 before rejoining in 2003.^[57]

At this same time, the group of ITER partners was expanding, with China and South Korea joining the project in 2003 and India formally joined in 2005.^[62][63][64]

There was a heated competition to host the ITER project with the candidates narrowed down to two possible sites: France and Japan. Russia, China, and the European Union supported the choice of Cadarache in France, while the United States, South Korea, and Japan support the choice of Rokkasho in Japan.^[57] In June 2005, it was officially announced that ITER would be built in the South of France at the Cadarache site.^[65] The negotiations that led to the decision ended in a compromise between the EU and Japan, in that Japan was promised 20% of the research staff on the French location of ITER, as well as the head of the administrative body of ITER. In addition, it was agreed that 8% of the ITER construction budget would go to partner facilities that would be built in Japan.^[66]

On 21 November 2006, at a ceremony hosted by French President Jacques Chirac at the Élysée Palace in Paris, an international consortium signed a formal agreement to build the reactor.^[67] Initial work to clear the site for construction began in Cadarache in March 2007 and, once this agreement was ratified by all partners, the ITER Organization was officially established on 24 October 2007.^[68]

In 2016, Australia became the first non-member partner of the project. ITER signed a technical cooperation agreement with the Australian Nuclear Science and Technology Organisation (ANSTO), granting this country access to research results of ITER in exchange for the construction of selected parts of the ITER machine.^[69][70] In 2017, Kazakhstan signed a cooperation agreement that laid the groundwork for technical collaboration between the National Nuclear Center of the Republic of Kazakhstan and ITER.^[71] Most recently, after collaborating with ITER in the early stages of the project, Canada signed a cooperation agreement in 2020 with a focus on tritium and tritium-related equipment.^[72]

The project began its five-year assembly phase in July 2020, launched by the French President, Emmanuel Macron in the presence of other members of the ITER project.^[73]

Directors-General[]

ITER is supervised by a governing body known as the ITER Council that is composed of representatives of the seven signatories to the ITER Agreement. The ITER Council is responsible for the overall direction of the organization and decides such issues as the budget.^[74] The ITER Council also appoints the director-general of the project. There have been three directors-general so far:

• 2005–2010: Kaname Ikeda
• 2010–2014: Osamu Motojima
• 2015–current: Bernard Bigot

The current director-general, Bernard Bigot, was appointed to reform the management and governance of the ITER project.^[75] In January 2019, the ITER Council voted unanimously to reappoint Bigot for a second five-year term.^[76]

Objectives[]

ITER's stated mission is to demonstrate the feasibility of fusion power as a large-scale, carbon-free source of energy.^[77] More specifically, the project has aims to:

• Momentarily produce a fusion plasma with thermal power ten times greater than the injected thermal power (a Q value of 10).
• Produce a steady-state plasma with a Q value greater than 5. (Q = 1 is scientific breakeven, as defined in fusion energy gain factor.)
• Maintain a fusion pulse for up to 8 minutes.
• Develop technologies and processes needed for a fusion power station — including superconducting magnets and remote handling (maintenance by robot).
• Verify tritium breeding concepts.
• Refine neutron shield / heat conversion technology (most of the energy in the D+T fusion reaction is released in the form of fast neutrons).

The objectives of the ITER project are not limited to creating the nuclear fusion device but are much broader, including building necessary technical, organizational, and logistical capabilities, skills, tools, supply chains, and culture enabling management of such megaprojects among participating countries, bootstrapping their local nuclear fusion industries.^[78][6]

Timeline and status[]

Aerial view of the ITER site in 2018

ITER construction status in 2018

Aerial view of the ITER site in 2020

As of May 2021 ITER is over 78% complete toward first plasma.^[79] Start is scheduled for late 2025.^[80][4]

The start of the project can be traced back to 1978 when the European Commission, Japan, United States, and USSR joined together for the International Tokamak Reactor (INTOR) Workshop. This initiative was held under the auspices of the International Atomic Energy Agency and its goals were to assess the readiness of magnetic fusion to move forward to the experimental power reactor (EPR) stage, to identify the additional R&D that must be undertaken, and to define the characteristics of such an EPR by means of a conceptual design. From 1978 to the middle of the 1980s, hundreds of fusion scientists and engineers in each participating country took part in a detailed assessment of the tokamak confinement system and the design possibilities for harnessing nuclear fusion energy.^[81][82]

In 1985, at the Geneva summit meeting in 1985, Mikhail Gorbachev suggested to Ronald Reagan that the two countries jointly undertake the construction of a tokamak EPR as proposed by the INTOR Workshop. The ITER project was initiated in 1988.^[83]

Ground was broken in 2007^[84] and construction of the ITER tokamak complex started in 2013.^[85]

Machine assembly was launched on 28 July 2020.^[86] The construction of the facility is expected to be completed in 2025 when commissioning of the reactor can commence and initial plasma experiments are scheduled to begin at the end of that year.^[87] When ITER becomes operational, it will be the largest magnetic confinement plasma physics experiment in use with a plasma volume of 840 cubic meters,^[88] surpassing the Joint European Torus by a factor of 8.

Reactor overview[]

When deuterium and tritium fuse, two nuclei come together to form a helium nucleus (an alpha particle), and a high-energy neutron.^[109]

²
₁D
+ ³
₁T
→ ⁴
₂He
+ ¹
₀n
+ 17.59 MeV

While nearly all stable isotopes lighter on the periodic table than iron-56 and nickel-62, which have the highest binding energy per nucleon, will fuse with some other isotope and release energy, deuterium and tritium are by far the most attractive for energy generation as they require the lowest activation energy (thus lowest temperature) to do so, while producing among the most energy per unit weight.^[110]

All proto- and mid-life stars radiate enormous amounts of energy generated by fusion processes.^[111] Mass for mass, the deuterium–tritium fusion process releases roughly three times as much energy as uranium-235 fission, and millions of times more energy than a chemical reaction such as the burning of coal.^[112] It is the goal of a fusion power station to harness this energy to produce electricity.

Activation energies (in most fusion systems this is the temperature required to initiate the reaction) for fusion reactions are generally 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 100 femtometers (1 × 10⁻¹³ meter) of each other, where the nuclei are increasingly likely to undergo quantum tunneling past the electrostatic barrier and the turning point where the 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. ITER uses cooling equipment like a cryopump to cool the magnets to close to absolute zero.^[113] 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 higher than 100 million °C.^[114] At ITER, the plasma will be heated to 150 million °C (about ten times the temperature at the core of the Sun)^[115] by ohmic heating (running a current through the plasma). Additional heating is applied using neutral beam injection (which cross magnetic field lines without a net deflection and will not cause a large electromagnetic disruption) and radio frequency (RF) or microwave heating.^[116]

At such high temperatures, particles have a large 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 a long enough time for much of the plasma to fuse.^[117] In ITER and many other magnetic confinement reactors, the plasma, a gas of charged particles, is confined using magnetic fields. A charged particle moving through a magnetic field experiences a force perpendicular to the direction of travel, resulting in centripetal acceleration, thereby confining it to move in a circle or helix around the lines of magnetic flux.^[118] ITER will use four types of magnets to contain the plasma: a central solenoid magnet, poloidal magnets around the edges of the tokamak, 18 D-shaped toroidal-field coils, and correction coils.^[119]

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.^[120] The containment vessel is subjected to a barrage of very energetic particles, where electrons, ions, photons, alpha particles, and neutrons constantly bombard it and degrade the structure. The material must be designed to endure this environment so that a power station would be economical. Tests of such materials will be carried out both at ITER and at IFMIF (International Fusion Materials Irradiation Facility).^[121]

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.^[122] Ideally, alpha particles will expend their energy in the plasma, further heating it.^[123]

The inner wall of the containment vessel will have 440 blanket modules that are designed to slow and absorb neutrons in a reliable and efficient manner and therefore protect the steel structure and the superconducting toroidal field magnets.^[124] At later stages of the ITER project, experimental blanket modules will be used to test breeding tritium for fuel from lithium-bearing ceramic pebbles contained within the blanket module following the following reactions:

¹
₀n
+ ⁶
₃Li
→ ³
₁T
+ ⁴
₂He

¹
₀n
+ ⁷
₃Li
→ ³
₁T
+ ⁴
₂He
+ ¹
₀n

where the reactant neutron is supplied by the D-T fusion reaction.^[125]

Energy absorbed from the fast neutrons is extracted and passed into the primary coolant. This heat energy would then be used to power an electricity-generating turbine in a real power station; in ITER this electricity generating system is not of scientific interest, so instead the heat will be extracted and disposed of.^[126]

Technical design[]

Drawing of the ITER tokamak and integrated plant systems

Vacuum vessel[]

Cross-section of part of the planned ITER fusion reaction vessel.

The vacuum vessel is the central part of the ITER machine: a double-walled steel container in which the plasma is contained by means of magnetic fields.

The ITER vacuum vessel will be twice as large and 16 times as heavy as any previously manufactured fusion vessel: each of the nine torus-shaped sectors will weigh approximately 500 tons for a total weight of 5000 tons. When all the shielding and port structures are included, this adds up to a total of 5,116 tonnes. Its external diameter will measure 19.4 metres (64 ft), the internal 6.5 metres (21 ft). Once assembled, the whole structure will be 11.3 metres (37 ft) high.^[120]

The primary function of the vacuum vessel is to provide a hermetically sealed plasma container. Its main components are the main vessel, the port structures and the supporting system. The main vessel is a double-walled structure with poloidal and toroidal stiffening ribs between 60-millimetre-thick (2.4 in) shells to reinforce the vessel structure. These ribs also form the flow passages for the cooling water. The space between the double walls will be filled with shield structures made of stainless steel. The inner surfaces of the vessel will act as the interface with breeder modules containing the breeder blanket component. These modules will provide shielding from the high-energy neutrons produced by the fusion reactions and some will also be used for tritium breeding concepts.^[127]

The vacuum vessel has a total of 44 openings that are known as ports – 18 upper, 17 equatorial, and 9 lower ports – that will be used for remote handling operations, diagnostic systems, neutral beam injections and vacuum pumping. Remote handling is made necessary by the radioactive interior of the reactor following a shutdown, which is caused by neutron bombardment during operation.^[128]

Vacuum pumping will be done before the start of fusion reactions to remove all molecules and to create the necessary low density that is about one million times lower than the density of air.^[129]

Breeder blanket[]

ITER will use a deuterium-tritium fuel, and while deuterium is abundant in nature, tritium is much rarer because it is a hydrogen isotope with a half-life of just 12.3 years and there is only approximately 3.5 kilograms of natural tritium on earth.^[130] Owing to this limited terrestrial supply of tritium, a key component of the ITER reactor design is the breeder blanket. This component, located adjacent to the vacuum vessel, serves to produce tritium through reaction with neutrons from the plasma. There are several reactions that produce tritium within the blanket.^[131] Lithium-6 produces tritium via (n,t) reactions with moderated neutrons, while Lithium-7 produces tritium via interactions with higher energy neutrons via (n,nt) reactions.^[132][133]

Concepts for the breeder blanket include helium-cooled lithium lead (HCLL), helium-cooled pebble bed (HCPB), and water-cooled lithium lead (WCLL) methods.^[134] Six different tritium breeding systems, known as Test Blanket Modules (TBM), will be tested in ITER and will share a common box geometry.^[135] Materials for use as breeder pebbles in the HCPB concept include lithium metatitanate and lithium orthosilicate.^[136] Requirements of breeder materials include good tritium production and extraction, mechanical stability and low levels of radioactive activation.^[137]

Magnet system[]

ITER is based on magnetic confinement fusion that uses magnetic fields to contain the fusion fuel in plasma form. The magnet system used in the ITER tokamak will be the largest superconducting magnet system ever built.^[138] The system will use four types of magnets to achieve plasma confinement: a central solenoid magnet, poloidal magnets, toroidal-field coils, and correction coils.^[119] The central solenoid coil will be 18 meters tall, 4.3 meters wide, and weigh 1000 tons.^[139] It will use superconducting niobium-tin to carry 45 kA and produce a peak field of more than 13 teslas.^[140][141]

The 18 toroidal field coils will also use niobium-tin. They are the most powerful superconductive magnets ever designed with a nominal peak field strength of 11.8 teslas and a stored magnetic energy of 41 gigajoules.^[142] Other lower field ITER magnets (poloidal field and correction coils) will use niobium-titanium for their superconducting elements.^[143]

Additional heating[]

To achieve fusion, plasma particles must be heated to temperatures that reach as high as 150 million °C and to achieve these extreme heats multiple heating methods must be used.^[144] Within the tokamak itself, changing magnetic fields produce a heating effect but external heating is also required. There will be three types of external heating in ITER:^[145]

• Two one-million volt heating neutral beam injectors (HNB) that will each provide about 16.5MW to the burning plasma, with the possibility to add a third injector. The beams generate electrically charged deuterium ions that are accelerated through five grids to reach the required energy of 1MV and the beams can operate for the entire plasma pulse duration, a total of up to 3600 seconds.^[146] The prototype is being built at the Neutral Beam Test Facility (NBTF),^[147] which was constructed in Padua, Italy. There is also a smaller neutral beam that will be used for diagnostics to help detect the amount of helium ash inside the tokamak.^[148]
• An ion cyclotron resonance heating (ICRH) system that will inject 20 MW of electromagnetic power into the plasma by using antennas to generate radio waves that have the same rate of oscillation as the ions in the plasma.^[149]
• An electron cyclotron resonance heating (ECRH) system that will heat electrons in the plasma using a high-intensity beam of electromagnetic radiation.^[150]

Cryostat[]

The ITER cryostat is a large 3,850-tonne stainless steel structure surrounding the vacuum vessel and the superconducting magnets, with the purpose of providing a super-cool vacuum environment.^[151] Its thickness (ranging from 50 to 250 millimetres (2.0 to 9.8 in)) will allow it to withstand the stresses induced by atmospheric pressure acting on the enclosed volume of 8,500 cubic meters.^[152] On 9 June 2020, Larsen & Toubro completed the delivery and installation of the cryostat module.^[153] The cryostat is the major component of the tokamak complex, which sits on a seismically isolated base.^{[154][155][156]}

Divertor[]

The divertor is a device within the tokamak that allows for removal of waste and impurities from the plasma while the reactor is operating. At ITER, the divertor will extract heat and ash that are created by the fusion process, while also protecting the surrounding walls and reducing plasma contamination.^[157]

The ITER divertor, which has been compared to a massive ashtray, is made of 54 pieces of stainless-steel parts that are known as cassettes. Each cassette weighs roughly eight tonnes and measures 0.8 meters x 2.3 meters by 3.5 meters. The divertor design and construction is being overseen by the Fusion For Energy agency.^[158]

When the ITER tokamak is in operation, the plasma-facing units endure heat spikes as high as 20 megawatts per square metre, which is more than four times higher than what is experienced by a spacecraft entering Earth's atmosphere.^[159]

The testing of the divertor is being done at the ITER Divertor Test Facility (IDTF) in Russia. This facility was created at the Efremov Institute in Saint Petersburg as part of the ITER Procurement Arrangement that spreads design and manufacturing across the project's member countries.^[160]

Cooling systems[]

The ITER tokamak will use interconnected cooling systems to manage the heat generated during operation. Most of the heat will be removed by a primary water cooling loop, itself cooled by water through a heat exchanger within the tokamak building's secondary confinement.^[161] The secondary cooling loop will be cooled by a larger complex, comprising a cooling tower, a 5 km (3.1 mi) pipeline supplying water from the Canal de Provence, and basins that allow cooling water to be cooled and tested for chemical contamination and tritium before being released into the Durance River. This system will need to dissipate an average power of 450 MW during the tokamak's operation.^[162] A liquid nitrogen system will provide a further 1300 kW of cooling to 80 K (−193.2 °C; −315.7 °F), and a liquid helium system will provide 75 kW of cooling to 4.5 K (−268.65 °C; −451.57 °F). The liquid helium system will be designed, manufactured, installed and commissioned by Air Liquide in France.^[163][164]

Location[]

Location of Cadarache in France

The process of selecting a location for ITER was long and drawn out. Japan proposed a site in Rokkasho, Aomori.^[165] Two European sites were considered, the Cadarache site in France and the Vandellòs site in Spain, but the European Competitiveness Council named Caderache as its official candidate in November 2003.^[166] Additionally, Canada announced a bid for the site in Clarington in May 2001, but withdrew from the race in 2003.^[167][168]

From this point on, the choice was between France and Japan. On 3 May 2005, the EU and Japan agreed to a process which would settle their dispute by July. At the final meeting in Moscow on 28 June 2005, the participating parties agreed to construct ITER at Cadarache with Japan receiving a privileged partnership that included a Japanese director-general for the project and a financial package to construct facilities in Japan.^[169]

Fusion for Energy, the EU agency in charge of the European contribution to the project, is located in Barcelona, Spain. Fusion for Energy (F4E) is the European Union's Joint Undertaking for ITER and the Development of Fusion Energy. According to the agency's website:

F4E is responsible for providing Europe's contribution to ITER, the world's largest scientific partnership that aims to demonstrate fusion as a viable and sustainable source of energy. [...] F4E also supports fusion research and development initiatives [...]^[170]

The ITER Neutral Beam Test Facility aimed at developing and optimizing the neutral beam injector prototype, is being constructed in Padova, Italy.^[171] It will be the only ITER facility out of the site in Cadarache.

Most of the buildings at ITER will or have been clad in an alternating pattern of reflective stainless steel and grey lacquered metal. This was done for aesthetic reasons to blend the buildings with their surrounding environment and to aid with thermal insulation.^[172]

Participants[]

Eight members participate in the ITER project.

Currently there are seven signatories to the ITER Agreement: the European Union (through the legally distinct organization Euratom), China, India, Japan, Russia, South Korea, and the United States.^[16]

As a consequence of Brexit, the United Kingdom formally withdrew from Euratom on 31 January 2020. However, under the terms of the EU-UK Trade and Cooperation Agreement, the United Kingdom remains a member of ITER as a part of Fusion for Energy following the end of the transition period on 31 December 2020.^[173]

In 2007, the ITER signed a Cooperation Agreement with Kazakhstan.^[71][174] In March 2009, Switzerland, an associate member of Euratom since 1979, also ratified the country's accession to the European Domestic Agency Fusion for Energy as a third country member.^[175]

In 2016, ITER announced a partnership with Australia for "technical cooperation in areas of mutual benefit and interest", but without Australia becoming a full member.^[70]

Thailand also has an official role in the project after a cooperation agreement was signed between the ITER Organization and the Thailand Institute of Nuclear Technology in 2018. The agreement provides courses and lectures to students and scientists in Thailand and facilitates relationships between Thailand and the ITER project.^[176]

Canada was previously a full member pulled out due to a lack of funding from the federal government. The lack of funding also resulted in Canada's withdrawing from its bid for the ITER site in 2003. Canada rejoined the project in 2020 via a cooperation agreement that focused on tritium and tritium-related equipment.^[72]

ITER's work is supervised by the ITER Council, which has the authority to appoint senior staff, amend regulations, decide on budgeting issues, and allow additional states or organizations to participate in ITER.^[177] The current Chairman of the ITER Council is Won Namkung,^[178] and the ITER Director-General is Bernard Bigot.

Members[]

•  China
•  European Union
  •   Switzerland (as a member of Euratom and Fusion for Energy)^[179]
  •  United Kingdom (as a part of Fusion for Energy)^[173]
•  India
•  Japan
•  Russia
•  South Korea
•  United States

Non-members[]

•  Australia (through the Australian Nuclear Science and Technology Organisation (ANSTO) in 2016)^[180]
•  Kazakhstan (through Kazakhstan's National Nuclear Center in 2017)^[180]
•  Thailand (through the Thailand Institute of Nuclear Technology (TINT) in 2018)^[181]
•  Canada (through the Government of Canada in 2020, mostly on the grounds of tritium)^[182]

Domestic agencies[]

Each member of the ITER project – China, the European Union, India, Japan, Korea, Russia, and the United States – has created a domestic agency to meet its contributions and procurement responsibilities. These agencies employ their own staff, have their own budget, and directly oversee all industrial contracts and subcontracting.^[183]

ITER China[]

China's contribution to ITER is managed through the China International Nuclear Fusion Energy Program or the CNDA. The Chinese agency is working on components such as the correction coil, magnet supports, the first wall, and shield blanket.^[184] China is also running experiments on their HL-2M tokamak in Chengdu to help support ITER research.^[185]

Fusion for Energy[]

Fusion for Energy, often referred to as F4E, is the European Union agency that is responsible for the European contribution to ITER. F4E was founded in 2007 and its headquarters based in Barcelona, Spain, with further offices in Cadarache, France, Garching, Germany, and Rokkasho, Japan.^[186] F4E is responsible for contributing to the design and manufacture of components such as the vacuum vessel, the divertor, and the magnets.^[187]

ITER-India[]

ITER-India is a special project run by India's Institute for Plasma Research.^[188] ITER-India's research facility is based in Ahmedabad in the Gujarat state. India's deliverables to the ITER project include the cryostat, in-vessel shielding, cooling and cooling water systems.^[189]

ITER Japan[]

Japan's National Institutes for Quantum and Radiological Sciences and Technology, or QST, is now the designated Japanese domestic agency for the ITER project. The organization is based in Chiba, Japan.^[190] Japan collaborates with the ITER Organization and ITER members to help design and produce components for the tokamak, including the blanket remote handling system, the central solenoid coils, the plasma diagnostics systems, and the neutral beam injection heating systems.^[191]

ITER Korea[]

ITER Korea was established in 2007 under Korea's National Fusion Research Institute and the organization is based in Daejeon, South Korea. Among the procurement items that ITER Korea is responsible for are four sectors of the vacuum vessel, the blanket shield block, thermal shields, and the tritium storage and delivery system.^[192]

ITER Russia[]

Russia occupies one of the key positions in the implementation of the international ITER Project.^[193] The Russian Federation's contribution to the ITER project lies in the manufacture and supply of high-tech equipment and basic reactor systems. The Russian Federation's contribution is being made under the aegis of Rosatom or the State Atomic Energy Corporation.^[194] The Russian Federation has multiple obligations to the ITER project, including the supply of 22 kilometers of conductors based on 80 tons of superconducting Nb3Sn strands for winding coils of a toroidal field and 11 km of conductors based on 40 tons of superconducting NbTi strands for windings of coils of a poloidal field of the ITER magnetic system. Russia is responsible for the manufacture of 179 of the most energy-intensive (up to 5 MW / sq.m) panels of the First Wall. The panels are covered with beryllium plates soldered to CuCrZr bronze, which is connected to a steel base. Panel size up to 2 m wide, 1.4 m high; its mass is about 1000 kg. The obligation of the Russian Federation also includes conducting thermal tests of ITER components that are facing the plasma.^[195] Today, Russia, thanks to its participation in the Project, has the full design documentation for the ITER reactor.

US ITER[]

US ITER part of the US Department of Energy and is managed by the Oak Ridge National Laboratory in Tennessee.^[196] US ITER is responsible for both the design and manufacturing of components for the ITER project and American involvement includes contributions to the tokamak cooling system, the diagnostics systems, the electron and ion cyclotron heating transmission lines, the toroidal and central solenoid magnet systems, and the pellet injection systems.^[197]

Funding[]

In 2006, the ITER Agreement was signed on the basis of an estimated cost of €5.9 billion over a ten-year period. In 2008, as a result of a design review, the estimate was revised upwards to approximately €19 billion.^[198] As of 2016, the total price of constructing and operating the experiment is expected to be in excess of €22 billion,^[19] an increase of €4.6 billion of its 2010 estimate,^[199] and of €9.6 billion from the 2009 estimate.^[200]

At the June 2005 conference in Moscow the participating members of the ITER cooperation agreed on the following division of funding contributions for the construction phase: 45.5% by the hosting member, the European Union, and the rest split between the non-hosting members at a rate of 9.1% each for China, India, Japan, South Korea, the Russian Federation and the USA.^{[201][202][203]} During the operation and deactivation phases, Euratom will contribute to 34% of the total costs,^[204] Japan and the United States 13 percent, and China, India, Korea, and Russia 10 percent.^[205]

Ninety percent of contributions will be delivered 'in-kind' using ITER's own currency, the ITER Units of Account (IUAs).^[205] Although Japan's financial contribution as a non-hosting member is one-eleventh of the total, the EU agreed to grant it a special status so that Japan will provide for two-elevenths of the research staff at Cadarache and be awarded two-elevenths of the construction contracts, while the European Union's staff and construction components contributions will be cut from five-elevenths to four-elevenths.

The American contribution to ITER has been the subject to debate. The U.S. Department of Energy has estimated the total construction costs to 2025, including in-kind contributions, to be $65 billion, although ITER disputes this calculation.^[22] After having reduced funding to ITER in 2017, the United States ended up doubling its initial budget to $122 million in-kind contribution in 2018.^[206] It is estimated the total contribution to ITER for the year 2020 was $247 million, an amount that is part of the U.S. Department of Energy's Fusion Energy Sciences program.^[207] Under a strategic plan to guide American fusion energy efforts that was approved in January 2021, the U.S. Department of Energy directed the Fusion Energy Sciences Advisory Committee to assume that the U.S. will continue to fund ITER for a ten-year period.^[208]

Support for the European budget for ITER has also varied over the course of the project. It was reported in December 2010 that the European Parliament had refused to approve a plan by member states to reallocate €1.4 billion from the budget to cover a shortfall in ITER building costs in 2012–13. The closure of the 2010 budget required this financing plan to be revised, and the European Commission (EC) was forced to put forward an ITER budgetary resolution proposal in 2011.^[209] In the end, the European contribution to ITER for the 2014 to 2020 period was set at €2.9 billion.^[210] Most recently, in February 2021, the European Council approved ITER financing of €5.61 billion for the period of 2021 to 2027.^[211]

Criticism[]

Protest against ITER in France, 2009. Construction of the ITER facility began in 2007, but the project has run into delays and budget overruns. In 2005, the World Nuclear Association said that fusion "presents so far insurmountable scientific and engineering challenges".^[212]

The ITER project has been criticized for issues such as its design and the fact that its budget diverted resources from other energy projects.

In 1999, an early technical concern arose that the 14.1 MeV neutrons produced by the fusion reactions will damage the materials from which the reactor is built.^[213] The question was to determine whether and how reactor walls can be designed to last long enough to make a commercial power station economically viable in the presence of the intense neutron bombardment. Research using materials such as tungsten to resist the effects of the neutrons better is currently being conducted at the Belgian nuclear research lab SCK CEN. For two years, various materials were tested under ITER-like environments. The post-irradiation studies should be completed by 2022.^[214] A related problem for a future commercial fusion power station is that the neutron bombardment will induce radioactivity in the reactor material itself.^[215] Maintaining and decommissioning a commercial reactor may thus be difficult and expensive. Another question was whether superconducting magnets would be damaged by neutron fluxes.^[216] A new special research facility, IFMIF, is planned to investigate this problem.^[217]

Another source of concern comes from the 2013 tokamak parameters database interpolation that revealed that the power load on tokamak divertors will be five times the previously expected value for ITER and much more for actual electricity-generating reactors. Given that the projected power load on the ITER divertor will already be very high, these new findings led to new design testing initiatives.^[218] One such test facility, the Divertor Tokamak Test (DTT) facility in Italy, is moving ahead;^[219] however, another facility, the Advanced Divertor eXperiment (ADX), has not yet received any funding.^[220]

A number of fusion researchers working on non-tokamak systems, such as the independent fusion scientist Eric Lerner, have argued that other fusion projects would be a fraction of ITER's cost and could be a potentially more viable and/or cost-effective path to fusion power.^[221] Many critics, such as Daniel Jassby, accuse ITER researchers of being unwilling to face up to the technical and economic potential problems posed by tokamak fusion schemes.^[222] The expected cost of ITER has risen from €5.9 billion to more than €20 billion, and the timeline for operation at full power was moved from the original estimate of 2016 to 2025. The project, however, was significantly delayed at the design stage as result of purposeful decision to decentralize its design and manufacturing among 35 participating states, which resulted in complexity that was unprecedented but consistent with the initial ITER goals of creating knowledge and expertise rather than merely producing energy.^[6]

One French anti-nuclear association, Sortir du nucléaire (Get Out of Nuclear Energy), which has had its founding charter signed by more than 900 other groups, has 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.^[223] However, another French environmental association Association des Ecologistes Pour le Nucléaire (AEPN) welcomes the ITER project as an important part of the response to climate change.^[6]

When France was announced as the site of the ITER project in 2005, several prominent European environmentalists expressed their opposition to the project. Rebecca Harms, Green/EFA member of the European Parliament's Committee on Industry, Research and Energy, told Euractiv in July 2005 that, "In the next 50 years, nuclear fusion will neither tackle climate change nor guarantee the security of our energy supply." In the same 2005 article, French Green party lawmaker Noël Mamère claimed that more concrete efforts to fight present-day global warming would 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 euros towards a project that has a term of 30–50 years when we're not even sure it will be effective."^[224]

Responses to criticism[]

Proponents believe that much of the ITER criticism is misleading and inaccurate, 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 should be hundreds of times less than that of a fission reactor, and that it should produce no long-lived radioactive waste, and that it is impossible for any such reactor to undergo a large-scale runaway chain reaction.^[225] A direct contact of the plasma with ITER inner walls would contaminate it, causing it to cool immediately and stop the fusion process. In addition, the amount of fuel contained in a fusion reactor chamber (one half gram of deuterium/tritium fuel^[226]) is only sufficient to sustain the fusion burn pulse from minutes up to an hour at most, whereas a fission reactor usually contains several years' worth of fuel.^[227] Moreover, some detritiation systems will be implemented, so that, at a fuel cycle inventory level of about 2 kg (4.4 lb), ITER will eventually need to recycle large amounts of tritium and at turnovers orders of magnitude higher than any preceding tritium facility worldwide.^[228]

In the case of an accident (or sabotage), it is expected that a fusion reactor would release far less radioactive pollution than would an ordinary fission nuclear station. Furthermore, ITER's type of fusion power has little in common with nuclear weapons technology, and does not produce the fissile materials necessary for the construction of a weapon. Proponents note that large-scale fusion power would be able to produce reliable electricity on demand, and with virtually zero pollution (no gaseous CO₂, SO₂, or NO_x by-products are produced).

According to researchers at a demonstration reactor in Japan, a fusion generator should be feasible in the 2030s and no later than the 2050s. Japan is pursuing its own research program with several operational facilities that are exploring several fusion paths.^[229]

In the United States alone, electricity accounts for US$210 billion in annual sales.^[230] Asia's electricity sector attracted US$93 billion in private investment between 1990 and 1999.^[231] These figures take into account only current prices. Proponents of ITER contend that an investment in research now should be viewed as an attempt to earn a far greater future return and a 2017-18 study of the impact of ITER investments on the EU economy have concluded that 'in the medium and long-term, there is likely to be a positive return on investment from the EU commitment to ITER.'^[232] Also, worldwide investment of less than US$1 billion per year into ITER is not incompatible with concurrent research into other methods of power generation, which in 2007 totaled US$16.9 billion.^[233]

Supporters of ITER emphasize that the only way to test ideas for withstanding the intense neutron flux is to subject materials experimentally to that flux, which is one of the primary missions of ITER and the IFMIF,^[226] and both facilities will be vitally important to that effort.^[234] The purpose of ITER is to explore the scientific and engineering questions that surround potential fusion power stations. It is nearly impossible to acquire satisfactory data for the properties of materials expected to be subject to an intense neutron flux, and burning plasmas are expected to have quite different properties from externally heated plasmas.^[235] Supporters contend that the answer to these questions requires the ITER experiment, especially in the light of the monumental potential benefits.^[236]

Furthermore, the main line of research via tokamaks has been developed to the point that it is now possible to undertake the penultimate step in magnetic confinement plasma physics research with a self-sustained reaction. In the tokamak research program, recent advances devoted to controlling the configuration of the plasma have led to the achievement of substantially improved energy and pressure confinement, which reduces the projected cost of electricity from such reactors by a factor of two to a value only about 50% more than the projected cost of electricity from advanced light-water reactors.^[237] In addition, progress in the development of advanced, low activation structural materials supports the promise of environmentally benign fusion reactors and research into alternate confinement concepts is yielding the promise of future improvements in confinement.^[238] Finally, supporters contend that other potential replacements to the fossil fuels have environmental issues of their own. Solar, wind, and hydroelectric power all have very low surface power density compared to ITER's successor DEMO which, at 2,000 MW, would have an energy density that exceeds even large fission power stations.^[239]

Safety of the project is regulated according to French and EU nuclear power regulations. In 2011, the French Nuclear Safety Authority (ASN) delivered a favorable opinion, and then, based on the French Act on Nuclear Transparency and Safety, the licensing application was subject to public enquiry that allowed the general public to submit requests for information regarding safety of the project. According to published safety assessments (approved by the ASN), in the worst case of reactor leak, released radioactivity will not exceed 1/1000 of natural background radiation and no evacuation of local residents will be required. The whole installation includes a number of stress tests to confirm efficiency of all barriers. The whole reactor building is built on top of almost 500 seismic suspension columns and the whole complex is located almost 300 m above sea level. Overall, extremely rare events such as 100-year flood of the nearby Durance river and 10,000-year earthquakes were assumed in the safety design of the complex and respective safeguards are part of the design.^[6]

Between 2008 and 2017, the project has generated 34,000 job-years in the EU economy alone. It is estimated that in the 2018–2030 period, it will generate a further 74,000 job-years and €15.9 billion in gross value.^[6]

Similar projects[]

Precursors to ITER were EAST, SST-1, KSTAR, JET,^[240] and Tore Supra.^[241] Similar reactors include the Wendelstein 7-X.^[242] Russia is developing the T-15MD tokamak in parallel with its participation in the ITER. Other planned and proposed fusion reactors include DEMO,^[243] NIF,^[244] HiPER,^[245] MAST,^[246] SST-2,^[247] CFETR (China Fusion Engineering Test Reactor), a 200 MW tokamak,^{[248][249][250][251]} and other 'DEMO-phase' national or private-sector fusion power plants.^[252][253]

See also[]

• Atoms for Peace (US Cold War-era science diplomacy strategy)
• Baruch Plan (post-War US attempt to internationalize fission)
• COLEX process (isotopic separation)
• Fusenet, European Fusion Education Network, 2008-2013
• Fusion for Energy, the Domestic Agency in charge of managing EU contributions to the ITER project
• International Fusion Materials Irradiation Facility, proposed, construction not started
• ITER Neutral Beam Test Facility, the facility dedicated to the development of the ITER neutral beam injector prototype
• JT-60, Japan's magnetic fusion program
• Nuclear power in France
• Science diplomacy
• Spherical Tokamak for Energy Production

References[]

Further reading[]

Claessens, Michel. (2020). ITER: The giant fusion reactor: Bringing a Sun to Earth. Springer.

Clery, Daniel. (2013). A Piece of the Sun. Gerald Duckworth & Co. Ltd.

ITER. (2018). ITER Research Plan within the Staged Approach (Level III - Provisional Version). ITER.

Wendell Horton, Jr, C., and Sadruddin Benkadda. (2015). ITER physics. World Scientific.

External links[]

Wikimedia Commons has media related to ITER.

• Official website
• Fusion for Energy website
• US ITER website
• ITER-India website
• ITER Korea website
• ITER Japan website
• ITER China website
• The New Yorker, 3 March 2014, Star in a Bottle, by Raffi Khatchadourian
• Archival material collected by Prof. McCray relating to ITER's early phase (1979–1989) can be consulted at the Historical Archives of the European Union in Florence
• "Way to New Energy" video (23:24) at YouTube, by RT, on 6 May 2014.
• The roles of the Host and the non-Host for the ITER Project. June 2005 The broader approach agreement with Japan.
• Fusion Electricity - A roadmap to the realisation of fusion energy EFDA 2012 - 8 missions, ITER, project plan with dependencies, ...