ITER: A Great Success

by Aarush Mehta — 23rd December 2022

ITER (initially the International Thermonuclear Experimental Reactor, iter meaning “the way” or “the path” in Latin[2][3][4]) is an international nuclear fusion research and engineering megaproject aimed at creating energy by replicating, on Earth, the fusion processes of the Sun. Upon completion of construction of the main reactor and first plasma, planned for late 2025,[5] it will be the world’s largest magnetic confinement plasma physics experiment and the largest experimental tokamak nuclear fusion reactor. It is being built next to the Cadarache facility in southern France.[6][7] 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.[8][9]The long-term goal of fusion research is to generate electricity. ITER’s stated purpose is scientific research, and technological demonstration of a large fusion reactor, without electricity generation.[10][8] ITER’s goals are to achieve enough fusion to produce 10 times as much thermal output power as thermal power absorbed by the plasma 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, and remote maintenance; to achieve and learn from a burning plasma; to test tritium breeding; and to demonstrate the safety of a fusion plant.[9][7] ITER’s thermonuclear fusion reactor will use over 300 MW of electrical power to cause the plasma to absorb 50 MW of thermal power, creating 500 MW of heat from fusion for periods of 400 to 600 seconds.[11] This would mean a ten-fold gain of plasma heating power (Q), as measured by heating input to thermal output, or Q ≥ 10.[12] As of 2022, the record for energy production using nuclear fusion is held by the National Ignition Facility reactor, which achieved a Q of 1.5 in December 2022.[13] 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.[14] As a research reactor, the heat energy generated will not be converted to electricity, but simply vented. [7][15][16]ITER is funded and run by seven member parties: China, the European Union, India, Japan, Russia, South Korea and the United States. The United Kingdom participates through EU’s Fusion for Energy (F4E), Switzerland participates through Euratom and F4E, and the project has cooperation agreements with Australia, Canada, Kazakhstan and Thailand.[17]Construction of the ITER complex in France started in 2013,[18] and assembly of the tokamak began in 2020.[19] The initial budget was close to €6 billion, but the total price of construction and operations is projected to be from €18 to €22 billion;[20][21] other estimates place the total cost between $45 billion and $65 billion, though these figures are disputed by ITER.[22][23] Regardless of the final cost, ITER has already been described as the most expensive science experiment of all time,[24] the most complicated engineering project in human history,[25] and one of the most ambitious human collaborations since the development of the International Space Station (€100 billion or $150 billion budget) and the Large Hadron Collider (€7.5 billion budget).[note 1][26][27] 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.[29]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.[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] Also this fusion reaction is the easiest to run. 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 selfsufficient.[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.[30] 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.[37] 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.[38][39]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.[40] Site preparation has begun near Cadarache center, France, and French President Emmanuel Macron launched the assembly phase of the project at a ceremony in 2020.[41] Under the revised schedule, work to achieve the first hydrogen plasma discharge was 70% complete in the mid of 2020 and considered on track.[42]One of the ITER objectives is a Q-value (“fusion gain”) of 10. Q = 1 is called a breakeven. The best result achieved in a tokamak is 0.67 in the JET tokamak.[43] The best result achieved for fusion in general is Q = 1.5, achieved in an inertial confinement fusion (ICF) experiment by the National Ignition Facility in late 2022.[13]For commercial fusion power stations, engineering gain factor is important. Engineering gain factor is defined as the ratio of a plant electrical power output to electrical power input of all plant’s internal systems (tokamak external heating systems, electromagnets, cryogenics plant, diagnostics and control systems, etc.).[44] Commercial fusion plants will be designed with engineering breakeven in mind (see DEMO). Some nuclear engineers consider a Q of 100 is required for commercial fusion power stations to be viable.[45]ITER will not produce electricity. Producing electricity from thermal sources is a well known process (used in many power stations) and ITER will not run with significant fusion power output continuously. Adding electricity production to ITER would raise the cost of the project and bring no value for experiments on the tokamak. The DEMO-class reactors that are planned to follow ITER are intended to demonstrate the net production of electricity.[46]One of the primary ITER objectives is to achieve a state of “burning plasma”. Burning plasma is the state of the plasma when more than 50% of the energy received for plasma heating is received from fusion reactions (not from external sources). No fusion reactors had created a burning plasma until the competing NIF fusion project reached the milestone on 8 August 2021.[47][48] At higher Q values, progressively bigger parts of plasma heating power will be produced by fusion reactions.[49] This reduces the power needed from external heating systems at high Q values. The bigger a tokamak is, the more fusion reaction-produced energy is preserved for internal plasma heating (and the less external heating is required), which also improves its Q-value. This is how ITER plans for its tokamak reactor to scale. The initial international cooperation for a nuclear fusion project that was the foundation of ITER began in 1978[50][51] 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. [52][53][54] 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.’ [56]

Content: Wikipedia

Brought by: AnimScience (Aarush Mehta)