The world’s largest and most ambitious fusion energy project has reached a turning point as Westinghouse Electric Company begins assembling the heart of ITER’s fusion reactor in Cadarache, southern France. The international effort, designed to replicate the energy of the sun, could one day provide humanity with an endless supply of clean, sustainable power.
Westinghouse leads final assembly of ITER’s tokamak core
In August 2025, the ITER fusion project entered one of its most technically demanding phases — the final assembly of the reactor’s tokamak core. Westinghouse, a global leader in nuclear technology, secured a €168 million contract to oversee the installation and welding of nine giant steel sectors that will form the tokamak’s vacuum vessel, the central chamber where fusion will occur.
This donut-shaped vessel must be perfectly circular and hermetically sealed, as it will contain plasma heated to over 150 million degrees Celsius—hotter than the core of the sun. Each sector, weighing about 400 tons, requires millimeter-level precision to ensure the system’s stability and safety during operation.
Westinghouse’s experience spans over a decade of work with Ansaldo Nucleare and Walter Tosto through the AMW consortium, which produced five of the nine reactor sectors. Their expertise ensures precision in both construction and integration, as the vessel must endure enormous magnetic and thermal stresses.
As former ITER Director-General Bernard Bigot once said, “Assembling this is like putting together a three-dimensional puzzle on an industrial scale.” Every weld, joint, and component must perform flawlessly to contain a process capable of replicating stellar reactions on Earth.
Global collaboration of unprecedented scale
ITER (International Thermonuclear Experimental Reactor) represents one of the greatest examples of scientific collaboration in history. Bringing together 35 nations—including the European Union, the United States, China, Japan, Russia, India, and South Korea—the project unites over half the world’s population and 85% of global GDP toward a common goal: sustainable energy.
Each participating country contributes precision-built components manufactured across four continents, shipped to France for assembly. This global supply chain transforms ITER into a model for future international cooperation in large-scale science and technology projects.
The result is more than just a reactor—it’s a demonstration of how humanity can coordinate resources and knowledge to solve planetary challenges, setting a precedent for future global energy innovations.
Technical ambitions and timeline challenges
ITER’s goal is to produce 500 megawatts of fusion power from just 50 megawatts of input—a tenfold return that would confirm the commercial viability of nuclear fusion. Achieving this would redefine global energy systems and represent a technological breakthrough comparable to the invention of electricity itself.
However, progress hasn’t come without challenges. Since construction began in 2010, ITER’s timeline has been extended multiple times due to technical complexity, supply chain coordination, and the unprecedented scale of the project. Originally scheduled for first plasma by 2018, the target now stands at 2035 for the first deuterium-tritium fusion experiments.
This delay underscores fusion’s enduring difficulty: creating and maintaining the extreme conditions necessary for sustained reaction. As the saying goes in the industry, “Fusion is always 30 years away”—a reminder of both the ambition and patience required for such pioneering work.
| ITER Component | Technical Challenge | Current Status |
|---|---|---|
| Vacuum Vessel | Perfect welding of 5,000-ton circular structure | Assembly underway under Westinghouse supervision |
| Superconducting Magnets | Building the world’s largest superconducting magnet system | Manufacturing complete, installation phase beginning |
| Cryogenic System | Maintaining -269°C for magnets while plasma exceeds 150M°C | All major components delivered, integration scheduled |
Beyond ITER : The roadmap to fusion power
ITER is not designed to power homes directly—it’s a scientific experiment paving the way for future commercial reactors like DEMO, which will produce electricity for the grid. The knowledge gained from ITER’s decades-long research will guide these next-generation systems, bridging the gap between theory and real-world application.
Fusion energy holds tremendous promise: it produces no long-lived radioactive waste, poses no risk of meltdown, and relies on abundant hydrogen isotopes found in seawater. A single liter of seawater contains enough deuterium to generate enormous amounts of energy when fused under proper conditions.
Although the path from ITER to commercial fusion may span several decades, the pursuit continues because the reward—a clean, virtually infinite power source—could transform civilization. Parallel research on other designs, including stellarators and inertial confinement systems, ensures a diverse ecosystem of fusion technologies pushing progress forward.
As Westinghouse meticulously assembles ITER’s core, the world edges closer to achieving what once seemed impossible: harnessing the power of the stars. This milestone not only marks a triumph of engineering but also demonstrates how international collaboration can turn visionary science into reality.