The world’s most ambitious fusion energy initiative has reached a defining point as Westinghouse Electric Company takes the lead in assembling the heart of ITER’s reactor. Located in Cadarache, southern France, this international megaproject seeks to replicate the power of the sun through nuclear fusion—aiming to deliver an endless source of clean, sustainable energy for generations to come.
Westinghouse leads final assembly of ITER’s tokamak core
In August 2025, the ITER project entered one of its most technically demanding stages: the final assembly of the reactor’s core. U.S.-based nuclear pioneer Westinghouse secured a €168 million contract to oversee this milestone, which involves the precision alignment and welding of nine massive steel sectors that will form the tokamak’s vacuum vessel—the central chamber where fusion takes place.
The tokamak’s vacuum vessel is a doughnut-shaped enclosure designed to contain plasma heated to over 150 million degrees Celsius—hotter than the core of the sun. Each of the nine 400-ton sectors must be welded with exact millimeter precision to create an airtight, perfectly circular structure capable of withstanding immense thermal and magnetic forces.
Westinghouse brings extensive experience to this effort, having worked for over a decade on ITER alongside Italian partners Ansaldo Nucleare and Walter Tosto as part of the AMW consortium. Together, they have already fabricated five of the nine vessel sectors. As former ITER Director-General Bernard Bigot once said, assembling this component is “like solving a three-dimensional puzzle on an industrial scale.” The task demands unparalleled precision to maintain perfect conditions for plasma containment—one of the most complex engineering feats ever attempted.
Global collaboration of unprecedented scale
ITER is a model of international scientific cooperation, uniting 35 nations—including the European Union, United States, China, Russia, Japan, India, and South Korea—representing more than half of the world’s population and the majority of its economic output.
Each participating country contributes key components built to strict standards before shipment to France for final assembly. This global collaboration functions like a vast scientific supply chain, with parts produced across four continents before converging at the Cadarache site. The project’s scale surpasses even other landmark collaborations in modern science, setting a precedent for how global challenges can be addressed collectively through shared innovation.
Key ITER contributions include:
- Europe: Construction site, infrastructure, and 45.6% of all components
- United States: Central solenoid magnet system and cooling water networks
- China: Correction coils and power supply elements
- Japan: Toroidal field coils and solenoid conductor
- Russia: Poloidal field coils and advanced diagnostic instruments
Technical ambitions and timeline challenges
ITER’s primary objective is to prove that fusion power can be produced at a commercial scale. The reactor is designed to generate 500 megawatts of fusion power using only 50 megawatts of input—an energy gain that would confirm fusion’s feasibility as a global power source.
However, since construction began in 2010, ITER has experienced multiple schedule adjustments due to engineering complexities, supply chain constraints, and the challenges of coordinating contributions from dozens of countries. While initial projections targeted the first plasma by 2018, current estimates suggest significant fusion testing using deuterium-tritium fuel may begin around 2035.
This evolving timeline underscores the immense technical challenge of sustaining nuclear fusion—a process often described as perpetually “30 years away.”
| ITER Component | Technical Challenge | Current Status |
|---|---|---|
| Vacuum Vessel | Precision welding of a 5,000-ton structure | Assembly underway under Westinghouse supervision |
| Superconducting Magnets | Building the world’s largest superconducting magnet system | Manufacturing completed; installation phase upcoming |
| Cryogenic System | Maintaining -269°C near plasma heated to 150 million°C | Components delivered; integration in progress |
Beyond ITER : The roadmap to fusion power
ITER is not an endpoint but a vital stepping stone toward practical fusion energy. While it will not generate power for the grid, the insights gained will pave the way for the next generation of reactors, known as DEMO, which aim to demonstrate commercial-scale electricity production.
Fusion energy offers transformative benefits: it produces no long-lived radioactive waste, carries no risk of meltdown, and relies on abundant hydrogen isotopes found in seawater. With virtually limitless fuel supplies, fusion could sustain civilization’s energy demands for millions of years.
The journey from ITER to commercial fusion will likely span decades, but the long-term payoff—a clean, inexhaustible energy source—continues to drive investment and global cooperation. Experts predict that ITER’s success will inspire multiple approaches to fusion beyond the tokamak design, including stellarators, inertial confinement systems, and magnetic mirror concepts, accelerating the overall path to viable fusion power.
As Westinghouse begins the intricate process of assembling ITER’s core, humanity stands at the threshold of mastering the same power that fuels the stars. This moment marks not only a triumph of science and engineering but also a profound testament to what nations can achieve when united by a shared vision for the future.