ITER Fusion Project Enters Critical Assembly Phase in France

A groundbreaking project aimed at harnessing the power of fusion energy has entered a pivotal stage in southern France. The International Thermonuclear Experimental Reactor (ITER) represents a colossal effort to recreate the sun’s energy production on Earth. Scientists aim to achieve nuclear fusion by fusing hydrogen isotopes, a process that occurs naturally in the sun’s core, where extreme heat and gravity facilitate fusion to create helium and release vast amounts of energy. Without the sun’s gravitational force, ITER will employ high temperatures to initiate fusion, marking a significant step toward clean energy solutions.

Final Assembly Begins for the Reactor Core

The current phase of ITER involves the meticulous assembly of its reactor core, a process marked by precision and extensive planning. The contract for this critical task was awarded to Westinghouse Electric Company for approximately $180 million. Engineers will weld together nine massive steel sectors, each weighing around 400 tons, to form the tokamak, a doughnut-shaped chamber designed to contain plasma heated to an astonishing 150 million degrees Celsius. The assembly requires pinpoint accuracy, with alignment tolerances as tight as 0.25 millimeters.

Given the extreme conditions the tokamak will face, its construction demands heat-resistant materials to prevent the structure from melting. Simultaneously, the heat generated must be contained within the tokamak long enough to facilitate nuclear fusion. To achieve this, scientists are developing a sophisticated 3,000-ton magnet system, which includes the Central Solenoid—a towering 60-foot stack of superconducting magnets. This magnet system, completed in April, is ready for installation and is capable of lifting an aircraft carrier, generating a magnetic field approximately 280,000 times stronger than the Earth’s own field. Such power is essential for controlling the plasma within the tokamak.

Additional Components and Future Goals

As the primary reactor vessel is being constructed, other significant components are also progressing. On October 2, 2025, Mitsubishi Heavy Industries and Japan’s National Institutes for Quantum Science and Technology announced the completion of the first Outer Vertical Target (OVT) for the divertor. This apparatus functions like an exhaust system, removing impurities such as helium ash and unburnt fuel from the plasma to maintain a stable fusion reaction. The divertor operates under extreme conditions, enduring heat loads that can peak at 20 megawatts per square meter. To withstand these harsh environments, it is constructed from materials like tungsten, known for its high melting point.

ITER’s ambitious goals distinguish it from similar projects, such as France’s WEST program, which set a world record for running a nuclear fusion reactor in February 2025. According to ITER’s official website, the facility intends to operate with “five times the plasma volume of the largest machine operating today.” Despite the monumental challenges it faces, the project has garnered collaboration from 33 nations, including some geopolitical rivals, united in the pursuit of a common goal.

The journey of ITER has not been without difficulties. Initially proposed in 1985, construction only commenced in 2010. The project’s budget has ballooned from an estimated $6 billion to over $20 billion, with delays attributed to various factors, including the COVID-19 pandemic and logistical challenges with international components. The planned start date for deuterium-tritium operation is now set for 2039.

As ITER progresses, it symbolizes not just a technological endeavor but also a global commitment to advancing nuclear energy. With ongoing developments, this project may pave the way for a sustainable energy future, contributing significantly to the world’s energy landscape.