International Thermonuclear Experimental Reactor

International Thermonuclear Experimental Reactor
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Name	International Thermonuclear Experimental Reactor
Caption	The ITER construction site in Cadarache, France, in 2020.
Device type	Tokamak
Location	Saint-Paul-lès-Durance, France
Affiliation	ITER Organization
Construction start	2013
Height	29 m
Diameter	28 m
Plasma volume	840 m³
Magnetic field	11.8 T (toroidal)
Heating power	73 MW
Fusion power goal	500 MW (Q ≥ 10)

International Thermonuclear Experimental Reactor is a major international nuclear fusion research and engineering project, representing the world's largest experimental tokamak reactor. Located at the Cadarache facility in Saint-Paul-lès-Durance, France, the project aims to demonstrate the scientific and technological feasibility of fusion power as a large-scale, carbon-free energy source. The initiative is a collaborative effort among seven major partners: the European Union, India, Japan, China, Russia, South Korea, and the United States.

Overview

The primary mission is to achieve a sustained fusion reaction producing significantly more energy than is required to initiate and maintain the hot plasma. Designed to produce a fusion power gain factor, or Q, of at least 10, the reactor aims to generate 500 megawatts of fusion power from 50 megawatts of input heating power. The device is a cornerstone of global efforts to develop practical fusion energy, building upon decades of research from preceding machines like Joint European Torus (JET) and the JT-60 in Japan. Its success is seen as a critical step toward the eventual construction of demonstration power plants, often referred to as DEMO-class reactors.

History and development

The concept originated from discussions between Mikhail Gorbachev of the Soviet Union and Ronald Reagan of the United States at the 1985 Geneva Summit, proposing international cooperation in fusion research. Conceptual design activities began in 1988, leading to the formation of the ITER Organization in 2007 after the signing of the ITER Agreement by the seven members. The site in Cadarache was selected in 2005 following a lengthy negotiation process that also considered Rokkasho in Japan. The project's history has been marked by complex political negotiations, budgetary revisions, and evolving technical designs, with formal construction commencing in 2013 after the approval of the final design.

Design and technology

The reactor is a massive tokamak device that will use powerful superconducting magnets, primarily made of niobium-tin and niobium-titanium, to confine a deuterium-tritium plasma within a toroidal vacuum vessel. Key technological components include the central solenoid, toroidal field coils, and divertor modules designed to handle extreme heat fluxes. The blanket system surrounding the plasma chamber will test breeding concepts for tritium, a fuel isotope. First plasma operations will utilize electron cyclotron resonance heating and ion cyclotron resonance heating, with future stages incorporating neutral beam injection systems developed by institutions like ITER India.

Participants and collaboration

The project is a unique model of global scientific cooperation, managed by the ITER Organization and funded and supplied by the seven member entities. The European Union, through Fusion for Energy, is the host party and contributes nearly half of the construction costs. Other members, including the United States Department of Energy, Japan Atomic Energy Agency, China National Nuclear Corporation, Korea Institute of Fusion Energy, Department of Atomic Energy (India), and Rosatom of Russia, are responsible for fabricating and delivering specific components. This in-kind procurement model involves thousands of scientists and engineers across hundreds of companies and research institutes like CERN and the Princeton Plasma Physics Laboratory.

Timeline and current status

Major assembly of the tokamak began in 2020, following the completion of the ITER Assembly Hall. Key milestones achieved include the delivery and installation of the first sector sub-assembly of the vacuum vessel and the lower cylinder of the cryostat manufactured by Larsen & Toubro in India. The project is working toward "First Plasma," currently scheduled for the late 2025 timeframe, which will mark the initiation of low-power operations. Full deuterium-tritium fusion experiments, aiming to demonstrate high fusion gain, are projected for the 2030s. The timeline has experienced several delays and cost increases since its inception, with the total estimated construction cost now exceeding several billion euros.

Scientific goals and challenges

The central scientific objective is to achieve a "burning plasma," where the heat from alpha particles produced by fusion reactions is sufficient to sustain the plasma temperature, minimizing external heating. It aims to investigate plasma stability at the scale of a power plant, integrate all essential fusion technologies, and test tritium breeding blanket modules. Major challenges include managing unprecedented plasma disruptions, mitigating intense neutron flux damage to materials, and demonstrating the reliable operation of complex superconducting magnet systems. Success would provide invaluable data for the design of subsequent reactors like the European-led DEMO and the CFETR in China.