Specialized robots, machine vision systems and force-sensing technologies are helping ITER tackle one of fusion’s toughest engineering challenges: assembling and eventually maintaining the interior of the tokamak. Giant robotic arms maneuvering multi-tonne components inside the ITER tokamak can resemble science fiction. Long, snake-like manipulators extend deep into the vacuum vessel through narrow ports, lifting and positioning bulky components inside one of the most constrained industrial environments ever constructed. But for the engineers responsible for in-vessel assembly, robotics is not futuristic experimentation. It is essential infrastructure for fusion construction and future maintenance.“We are preparing for the future while we are building this machine,” said ITER handling and robotics expert Raphael Hery in a dedicated session on the topic during the third ITER Public-Private Fusion Workshop in April. These developments are part of the overall strategy to prepare for the in-vessel component installation phase, during which a variety of components will have to fit inside the vessel within limited space.Because radiation levels inside the vacuum vessel will eventually make direct human access impractical during high-power operations, ITER’s in-vessel components were designed from the beginning for remote handling.  This 4-metre-tall FANUC M2300i robot—the heaviest commercial robot available on the market—has a payload of 2.3 tonnes. The ITER team is using it as a development platform to trial and integrate the tools and technologies planned for ITER's in-vessel assembly robots, for example the installation of blanket modules seen here. That requirement creates engineering challenges far beyond those found in conventional industry. Some blanket manifolds rise as high as 7.5 metres. Blanket shield blocks can weigh up to 4 tonnes, while divertor cassettes reach 9 tonnes. Many of these components must be maneuvered through narrow openings, transported to locations around the vessel and positioned with extreme precision in an environment tightly packed with structures, cooling systems and plasma-facing components. As a result, the robotic technologies being developed for today’s assembly activities are also laying the groundwork for future maintenance operations.Building robots for fusionTo meet these requirements, ITER and its industrial partners are developing a new generation of heavy-duty robotics adapted specifically for fusion environments. “Many of the systems we use do not have any equivalent on the market today,” says Hery.One example is the blanket assembly transporter, a long-reach robotic arm designed to install shield blocks and first-wall components inside the vessel (see the grey and black tool in the image, left). ITER is also developing specialized divertor assembly systems, remotely operated handling equipment and modular staging platforms that allow personnel to work safely alongside robotic operations during assembly phases.The robots themselves are only part of the challenge. ITER engineers also need systems capable of something closer to human perception. â€œWhat a typical robot lacks is the sense of touch and the sense of vision,” says Hery.That challenge has driven increasingly close collaboration between ITER, universities, startups and specialized industrial suppliers working together to adapt existing technologies—and in some cases invent entirely new ones—for fusion applications.Giving robots sightPhysical reach and lifting capacity are only part of the problem. Operators also need robots that can perceive and react to their surroundings with extreme precision. Workshop participant Olli Suominen described how machine-vision systems originally developed through academic research are now being adapted for ITER’s remote-handling operations.Suominen began the work as a researcher at Tampere University in Finland before later joining the spin-off company Operview, which now collaborates with ITER on robotic vision technologies.The challenge his team is trying to solve is deceptively simple. Operators controlling robots through camera feeds can generally see what they are doing, but precise alignment inside the vessel becomes far more difficult when handling large components over long distances.Large robotic arms naturally deform under heavy loads. Once multi-tonne components are attached, the robot’s actual position can differ from its theoretical one. Vision systems help compensate for those deviations, allowing operators to align components precisely using optical markers laser-etched directly onto stainless steel surfaces (see the Pi-Tag fiducial marker above)—a solution that is compatible with vacuum and radiation environments. â€œIf you add cameras that will behave as your eyes and your sense of sight, then the robot can use references in its environment to know where it is exactly,” says Hery, adding that tests have shown the vision systems can achieve positioning precision of roughly 0.06 millimetres—smaller than the thickness of a human hair.Giving robots touchITER engineers are also equipping assembly and maintenance robots with tactile feedback. Working with German measurement technology company HBK, ITER is developing specialized force-torque sensors that allow robotic systems to detect contact forces while manipulating shield blocks and first-wall components.“These sensors are able to provide a sense of touch,” company representative Tim Ahlswede said during the workshop.The sensors help the robot control system determine when a component has touched another surface, avoiding damaging collisions and adjusting the motion of the long robotic arm that extends into the vessel, according to Ahlswede. “When a heavy object is attached to a long arm it bends slightly, like a fishing rod when a fish is caught.”  In the basement of the Tokamak Assembly Preparation Building, operators are busy calibrating the Godzilla robot. The force and torque sensors seen on the tables (bottom right) will be tested on the end of Godzilla's robotic arm. Without force sensing, releasing the heavy load could trigger dangerous movement throughout the structure. The sensors allow the control system to gradually reduce tension from the payload before disengagement, minimizing vibration and improving positional stability inside the vessel.Fusion environments also impose unusual engineering requirements on the sensors themselves. One of the biggest challenges for the HBK team was ensuring the systems could tolerate radiation exposure while still maintaining precise measurement performance. The company tested specialized strain gauges, cabling and materials at irradiation facilities before selecting suitable components. ITER’s seismic requirements added another layer of complexity, requiring the sensors to tolerate loads far beyond normal operating conditions.Building an innovation ecosystemEngineers at ITER typically develop the initial concepts and preliminary designs internally before working with industrial partners to transform those ideas into operational systems. â€œWe push the design to its theoretical performance limits,” Hery says. â€œThen, to make it a reality, we liaise with expert companies.”In some cases, that means adapting existing industrial technologies to ITER’s specific requirements. In others, it means developing entirely new approaches.For Hery, that collaborative model is becoming central to ITER’s in-vessel assembly progress. â€œWe are developing robotic technologies at an unprecedented combination of size and payload capacity scale,” he says.The systems being developed for ITER are pushing industrial robotics into new territory and creating a new class of heavy-duty robotics adapted specifically for fusion environments.

The B1M—a video channel known for its coverage of construction, architecture and engineering projects—has published two features on ITER in the last four years that have attracted more than nine million views. Now, the channel's founder is featuring the ITER project in a new book. The B1M first visited ITER in 2022 to film We Went Inside the Largest Nuclear Fusion Reactor. A follow-up feature, This is the World's Most Complex Construction Project (2024), became the channel's most-watched video to date. "By far," the B1M founder Fred Mills notes.Last week, Mills was at the Royal Geographical Society in London to present Mega Builds, Ten Colossal Construction Projects That Will Change Our World, a book that charts the story of how ten colossal megaprojects, including ITER, are redefining what’s possible. “The trajectory of our civilization is being authored today, all around us, not in words on a page but in steel and concrete, and by an industry that most people completely overlook.” When choosing a prize giveaway for the launch of his book competition, he said the choice of a trip to ITER was an easy one.“From the first time I came here … I knew about it, I had researched it, I understood how it worked. But it’s not until you walk into that Assembly Hall and you see that environment around you that the goosebumps kind of come out on your skin. We were thinking about what would be a good prize giveaway for someone to enter the book competition and ITER was literally a no-brainer.”Winner Darren Williams, a structural engineer, travelled to ITER with Mills on 28 May. By chance, they met ITER Director-General Pietro Barabaschi in the Assembly Hall, who was pleased to receive a copy of the book.Mega Builds: Ten Colossal Construction Projects That Will Change Our World, ISBN 978-0-7535-6161-4

As ITER is actively installing the first wave-producing gyrotrons of its electron cyclotron heating system, the European Domestic Agency Fusion for Energy was featuring ITER technologies like launchers, gyrotrons and diagnostics in Barcelona at the 23rd Joint Workshop on Electron Cyclotron Emission and Resonance Heating (EC-23) from 18 to 22 May.Electron cyclotron (EC) waves will play a pivotal role in ITER, and in future fusion reactors more broadly, by providing reliable and efficient heating of the burning plasma. Achieving ITER's scientific objectives requires substantial electron cyclotron resonance heating power, making the development of high-power gyrotrons and robust wave transmission and injection systems a critical area of research and engineering.The workshop attracted 150 international experts, the highest turnout ever for this biennial scientific event created in 1979. A strong showing from early-career professionals was also a highlight.