ITER Project Advances with Critical Assembly Phase in France

The International Thermonuclear Experimental Reactor (ITER), located in southern France, is progressing into a pivotal phase of its ambitious mission to achieve nuclear fusion. This project aims to replicate the process that powers the sun, generating a clean and virtually limitless source of energy. Scientists believe that by successfully harnessing nuclear fusion, humanity could produce energy that is approximately four million times more efficient than coal, using fuel that can be extracted from seawater.

Key Developments in Reactor Core Assembly

As of now, ITER has officially commenced the final assembly of its reactor core, marking a significant milestone in the project’s timeline. The contract for this critical task has been awarded to Westinghouse Electric Company, an American nuclear firm, for a total of $180 million. Engineers will weld together nine massive steel sectors, each weighing around 400 tons, to construct the tokamak—a vacuum vessel designed to contain plasma heated to an astonishing 150 million degrees Celsius.

The assembly process demands meticulous precision, with some alignments requiring a maximum tolerance of just 0.25 millimeters. This level of accuracy is essential for maintaining the integrity of the tokamak, which must withstand extreme temperatures without the walls melting. Furthermore, a sophisticated magnet system, featuring a Central Solenoid comprised of superconducting magnets, is being constructed as an “invisible shield” around the tokamak. This magnet system, weighing 3,000 tons, produces a magnetic field approximately 280,000 times stronger than Earth’s gravitational pull to effectively control the plasma within.

Advancements in Supporting Technologies

While the main reactor vessel is under construction, other critical components are also nearing completion. On October 2, 2025, Mitsubishi Heavy Industries and the Japan National Institutes for Quantum Science and Technology announced the successful completion of the first Outer Vertical Target (OVT) of the divertor. This apparatus acts as an exhaust system, designed to extract impurities from the plasma and maintain stability during the fusion reaction. The divertor will endure extreme conditions, with heat loads reaching up to 20 megawatts per square meter, necessitating the use of advanced materials such as tungsten, known for its high melting point.

ITER stands out from similar projects due to its unprecedented scale. It plans to operate with a plasma volume that is five times larger than the largest existing nuclear fusion machine. Despite its ambitious goals, the project has faced significant challenges since its inception in 1985. Construction officially began in 2010, but the budget has surged from an initial estimate of $6 billion to over $20 billion. Delays have arisen from various issues, including the COVID-19 pandemic and difficulties in assembling components produced in different countries. The start of deuterium-tritium operations is now targeted for 2039.

Notably, ITER has united 33 nations, including geopolitical rivals, in pursuit of this common goal. The project’s progress mirrors a broader global interest in nuclear energy, as countries explore sustainable alternatives to fossil fuels. With its groundbreaking technologies and international collaboration, ITER represents a hopeful step towards a cleaner and more secure energy future.