ITER Project

The International Thermonuclear Experimental Reactor (ITER) is a scientific and engineering endeavor aimed at reproducing on Earth the nuclear fusion process that powers stars under controlled conditions. The project’s primary objective is to establish the scientific evidence and technological infrastructure necessary to demonstrate the future viability of fusion energy as a sustainable, safe, and environmentally friendly power source.

In this context, ITER encompasses the construction of a fusion reactor of the tokamak type, one of the most advanced magnetic confinement systems ever designed. This reactor will confine high-temperature plasma using powerful magnetic fields, enabling the observation and measurement of energy released from the fusion of hydrogen isotopes. This experimental system aims to generate comprehensive data in physics, engineering, and materials science essential for the design and operation of future commercial fusion power plants.

Carried out in the Cadarache region of southern France, the project is one of the largest international scientific collaborations in the world. Led by the European Union, this initiative is supported by joint contributions from major economic and scientific actors including China, India, Japan, South Korea, Russia, and the United States. These countries share broad responsibilities across the project, from manufacturing engineering components and providing research infrastructure to supplying financial resources and scientific expertise.

In conclusion, ITER can be regarded not merely as a reactor design but as a large-scale research initiative to assess the feasibility of fusion energy. The project serves as an example of how international cooperation can be organized to achieve long-term scientific and technological goals. At the same time, it functions as a critical test platform for analyzing the potential contributions of fusion-based energy production to energy security and the reduction of carbon emissions.

Difference Between Fusion and Fission

Nuclear energy is based on two fundamental physical processes occurring in atomic nuclei: fission and fusion reactions. These two processes are the core nuclear mechanisms that convert mass into energy; however, they differ significantly in their operation, technical requirements, and environmental impacts.

Fission is the process underlying current nuclear power plants. In this reaction, a heavy atomic nucleus such as uranium or plutonium becomes unstable upon interaction with a neutron and splits into two smaller nuclei. This splitting releases large amounts of energy, additional neutrons, and radioactive byproducts. Although this process can be sustained through a chain reaction mechanism and is efficient for energy production, it generates long-lived radioactive waste, posing serious environmental and safety concerns. Additionally, potential loss of control in fission reactors carries the risk of high-consequence accidents.

Fusion, by contrast, is a process observed in nature, particularly in Sun and other stars. In this reaction, light atomic nuclei such as deuterium and tritium fuse under extreme temperature and pressure conditions to form a heavier nucleus like helium. The energy released during fusion is much greater per unit mass than that from fission. Therefore, fusion is theoretically viewed as a clean, safe, and nearly limitless energy source. Fusion reactions do not carry the risk of a chain reaction and therefore cannot undergo uncontrolled runaway, nor do they produce long-lived radioactive waste.

However, achieving practical fusion requires overcoming extraordinarily complex physical conditions. Creating strong magnetic fields capable of stably confining plasma at millions of degrees and sustaining this plasma without significant energy loss represents a major challenge in engineering and materials science. For this reason, despite being theoretically possible, fusion has not yet reached the stage of commercial-scale energy production. Current research in this field is primarily conducted through magnetic confinement systems such as tokamaks and stellarators; international projects like ITER aim to develop the fundamental scientific and technological infrastructure needed for fusion to become a viable energy source in the future.

Project Objectives and Goals

The primary objective of the International Thermonuclear Experimental Reactor (ITER) project is not to build a direct commercial fusion power plant but to scientifically and technologically demonstrate that fusion energy can be produced on a large scale and sustainably. This goal seeks to establish the engineering, materials science, and plasma physics foundations necessary to pave the way for future industrial fusion power plants.

To this end, ITER is structured around a series of strategic and experimental goals. The primary goal is to achieve net energy gain, meaning the reactor must produce more energy from fusion reactions than the energy used to heat the plasma. In this way, the system will function for the first time as an “energy-producing” fusion reactor at experimental scale. This success will demonstrate that fusion is not only feasible in laboratory conditions but also as a viable method for energy production.

A second critical goal is to reach the “burning plasma” state, in which the plasma is sustained largely by its own internal energy. At this stage, the plasma’s temperature is maintained by its own fusion reactions without external energy input, marking a pivotal milestone toward achieving natural energy balance in fusion.

Additionally, ITER aims to experimentally validate several key technologies required for the operation of future fusion reactors. These include:

• Production and recovery of tritium fuel within the reactor for the fusion process,
• Stable control of fusion power,
• Efficient removal of excess heat generated at the reactor walls and its transfer to electricity generation systems,
• Testing of material durability under prolonged radiation conditions,

The achievement of these goals represents a critical step toward moving fusion energy from a theoretical option to a viable energy production method. The technical and scientific outcomes of ITER will serve as a foundational reference for the engineering, materials performance, and plasma control requirements of future commercial fusion plants such as DEMO.

Tokamak Reactor and Operating Principle

At the heart of the ITER project lies a large-scale magnetic confinement system known as the tokamak, which forms the core of fusion research. The term “tokamak” is an abbreviation of the Russian phrase “toroidalnaya kamera s magnitnymi katushkami,” meaning “toroidal chamber with magnetic coils.” Developed by Soviet physicists in the 1950s, this design has become the most widely used reactor architecture in fusion research due to its ability to stably confine plasma.

The tokamak is designed to contain plasma—the ionized state of matter consisting of atomic nuclei stripped of their electrons—within a closed magnetic field. The structure comprises a toroidal vacuum chamber, powerful superconducting magnets, heating systems, and a complex cooling infrastructure.

The fusion process in ITER occurs in several key stages: First, the two hydrogen isotopes, deuterium and tritium, are injected into the toroidal vacuum chamber. Then, a strong electric current passed through the gas ionizes it and transforms it into plasma. The plasma is further heated to extremely high temperatures using specialized heating systems—temperatures far exceeding those at the core of the Sun. At this point, deuterium and tritium nuclei fuse together, initiating fusion reaction.

Superconducting magnets surrounding the tokamak create an extraordinarily powerful magnetic cage that prevents the plasma from contacting the walls. This magnetic field simultaneously confines the plasma at the center and shapes it into the desired geometry. High-energy neutrons produced by fusion pass unaffected through the magnetic field and strike the reactor walls, transferring their energy as heat. This heat is carried away by circulating fluids in the reactor’s cooling systems.

In future commercial fusion reactors, this thermal energy will be used to generate electricity via steam turbines, as in conventional thermal power plants. Thus, the tokamak is not merely an experimental device but the most advanced physical system developed to achieve practical and sustainable fusion energy. ITER’s tokamak structure is regarded as the most concrete engineering expression of humanity’s effort to replicate the energy production process of stars on Earth.

Technical Features and Components

The ITER project is one of the most comprehensive and technically complex engineering endeavors in human history. This massive structure consists of tens of thousands of integrated components and is being constructed through a multinational supply chain. At the center of the project, the tokamak stands out for its extraordinary dimensions and technological complexity. With a mass of more than 23,000 tons, this system is a colossal engineering structure designed to stably confine fusion plasma.

The most critical components of the tokamak are the superconducting magnets. This magnet system comprises nineteen toroidal field coils encircling the plasma and a central solenoid, regarded as the “heart” of the reactor. The toroidal coils maintain the plasma’s toroidal geometry, while the central solenoid initiates and sustains the electric current within the plasma. Each magnet possesses extraordinary engineering properties in terms of mechanical strength and electromagnetic performance.

These magnets are manufactured from advanced superconducting materials such as niobium-tin (Nb₃Sn) and niobium-titanium (NbTi). To achieve superconductivity, the system is cooled to temperatures near absolute zero using liquid helium. This enables the magnets to generate extraordinarily powerful magnetic fields capable of controlling plasma currents of millions of amperes and providing the magnetic confinement necessary for fusion reactions to occur.

The reactor’s fuel cycle also constitutes a major part of ITER’s research objectives. Deuterium, the primary fuel for fusion, is naturally abundant in seawater and easily obtainable. However, the other isotope required for fusion, tritium, exists in only trace quantities in nature and must be continuously produced due to its short half-life. Therefore, ITER will test a method of producing its own tritium using lithium-containing modules placed in the reactor walls, which capture neutrons released during fusion to breed tritium.

This technology aims to ensure the the energy cycle's sustainability of future fusion power plants by enabling fuel self-sufficiency. Thus, ITER will not only demonstrate the scientific feasibility of fusion energy but also shape the infrastructure necessary for fusion to become economically and technically viable at an industrial scale.

History and International Cooperation

The idea of establishing global cooperation in fusion energy research first emerged in 1985 during a summit between U.S. President Ronald Reagan and Soviet General Secretary Mikhail Gorbachev. This meeting marked the beginning of an effort to create a foundation for peaceful technological collaboration through scientific diplomacy during the Cold War. Following years of technical assessments and diplomatic negotiations, the ITER project was formally launched in 2006 with the participation of the European Union, the United States, Russia, China, South Korea, India, and Japan. The construction site was chosen as Cadarache in southern France, a region with a long-standing legacy in nuclear research.

ITER operates on a unique “in-kind contribution” model, in which each member country produces and delivers specific components of the project rather than making direct cash payments. This model mobilizes the scientific capacity of each nation while enabling shared technical responsibility within the project. For example, the United States is responsible for manufacturing the central solenoid, the heart of the reactor; the European Union undertakes critical components such as the vacuum vessel and cooling systems; Russia is responsible for developing superconducting materials and gyrotron heating systems; Japan and South Korea handle the production of magnet structures and plasma support equipment; and India provides key elements of the cryogenic systems, power supplies, and control infrastructure.

Because of this structure, ITER is regarded as a unique example of scientific cooperation that transcends geopolitical differences. The project has been one of the most advanced applications of science diplomacy, contributing to the rebuilding of international trust in the post-Cold War era. Over time, Canada withdrew from the project for financial reasons, while Kazakhstan expressed interest by formally applying for participation.

In conclusion, ITER not only reveals the potential of fusion energy but also demonstrates how countries with different political and cultural systems can unite around a common scientific goal. In this sense, the project is both a harbinger of a new era in energy production and a symbol of international cooperation at the engineering level.

Cost, Timeline, and Challenges

The ITER project has faced unprecedented challenges due to its scale, technical complexity, and multinational structure. Launched in 2006 with an estimated budget of approximately 5 billion euros and a 10-year construction schedule, the project has since experienced significant delays and cost overruns due to unforeseen technical and administrative issues, production setbacks, and escalating expenses. Current estimates indicate that the total cost of ITER has risen to several times the original projection, and the first plasma generation has been postponed far beyond the initial timeline.^【1】

Major causes of these delays include the technical difficulties encountered in developing and manufacturing components that are the first of their kind. Each component is produced with micrometer-level precision and fabricated in different countries before being assembled at the construction site in France. This creates complex logistical and quality control challenges. Additionally, manufacturing defects identified in some equipment have necessitated rework, resulting in further time losses.

Furthermore, the global COVID-19 pandemic caused severe disruptions to construction and supply chains, and travel restrictions significantly hampered coordination among international teams. During the same period, French nuclear safety authorities introduced new technical requirements regarding radiation safety, material durability, and emergency protocols. These additional regulations have necessitated revisions to both engineering plans and testing procedures.^【2】

Current projections estimate that ITER’s first plasma experiments will begin around 2035. These delays and cost increases have made ITER one of the longest-running and most expensive scientific infrastructure projects in history. Nevertheless, member countries remain committed to continuing the project and continue to view ITER as a pivotal turning point in shaping the future of fusion energy.

This situation also demonstrates that the project is not only a scientific endeavor but also a test of political and strategic resilience: ITER remains one of the rare examples proving that long-term international scientific collaboration can endure despite all setbacks.

The Future of Energy and Environmental Impacts

Fusion energy holds significant potential in terms of environmental, safety, and sustainability considerations. In this context, the ITER project is viewed not merely as a scientific experiment but as a strategic milestone in the transition to a carbon-free energy future.

The most striking feature of fusion energy is its ability to generate large amounts of energy without emitting carbon. This is of great importance for reducing global greenhouse gas emissions and combating climate change. Moreover, unlike fission reactors, fusion does not produce long-lived, high-level radioactive waste; the byproducts are short-lived and have limited environmental impact.

In terms of safety, fusion offers distinct advantages over current nuclear technologies. Fusion reactions can only be sustained under extremely precise conditions of temperature, pressure, and magnetic field. If any of these conditions are disrupted, the reaction ceases spontaneously. Therefore, fusion reactors carry no risk of chain reactions or nuclear meltdown.

Fusion is also an extremely sustainable energy source in terms of fuel supply. Deuterium is a hydrogen isotope naturally abundant in seawater; tritium can be produced from lithium. This means fusion energy is based on a fuel source that is virtually inexhaustible. Moreover, fusion fuel offers energy density millions of times greater than fossil fuels.

Successfully achieving ITER’s goals will enable this technology to move beyond theoretical possibility and become a permanent option in the global energy supply. Because fusion energy can provide uninterrupted baseload power for large cities and industrial regions, it is also regarded as a strategic solution in terms of energy security and sustainable development.

In this sense, ITER is not merely an effort to build a reactor; it represents the technological foundation of a future vision in which dependence on fossil fuels is reduced, environmental risks are minimized, and global equity in energy production is strengthened.