ITER’s Godzilla robot masters fusion assembly tools ahead of 2026 tokamak build

ITER’s Godzilla robot flexes its 5-metre arm in the Tokamak Assembly Preparation Building, fine-tuning tools for the vacuum vessel’s high-stakes fusion build.

(Image courtesy of ITER)

Inside the basement of ITER’s Tokamak Assembly Preparation Building, a 4-metre industrial robot nicknamed Godzilla is being calibrated by a small team of technicians. The machine, the most powerful commercially available robot of its kind, can extend its arm to 5 metres and heft loads up to 2.3 tonnes. It is not, however, going anywhere near the actual tokamak. Its job is to serve as a test bed for the tools and sensing systems that will eventually go inside one of the most inaccessible and hostile environments humans have ever engineered.

That environment is the inner wall of ITER’s vacuum vessel, where nearly 20,000 components need to be installed across roughly half a dozen concentric system layers. Working outward from the plasma-facing first-wall panels, through shield blocks, manifolds, and electromagnetic coils for vertical stabilisation and ELM suppression, each layer has to be installed in the correct sequence within a chamber that leaves very little room for error, repositioning, or damaged hardware.

The strategy developed to handle this is called Rolling Waves. Rather than completing one layer entirely before starting the next, specialised teams and their corresponding assembly robots advance through sections of the vessel in parallel, with one team installing a layer while another moves in behind to begin the next. Raphaël Hery, who previously worked on remote handling for the Laser Mégajoule inertial fusion facility and the IRIS deep-sea inspection system, describes the approach as a way to compress the overall installation timeline and reduce the risks that come from multiple teams working in close proximity.

The two primary machines that will carry out most of this work are the in-vessel tower crane, already produced and now being adapted and optimised, and the blanket assembly transporter, a 36-tonne machine currently in detailed design at Larsen and Toubro in India. Two of the transporters and one tower crane, with a second held in reserve, will run in parallel. Human operators working from bespoke mobile elevation platforms fitted with zero-gravity arms will handle tasks that robots cannot.

What makes the in-vessel robots different from standard industrial machines is that they need two capabilities that off-the-shelf systems simply do not have. The first is vision. A camera and alignment system developed by Europe’s Fusion for Energy domestic agency will allow them to precisely locate installation targets on the vessel wall. The second is force and torque sensing, which gives the robots a form of haptic feedback, letting them detect and control the loads being applied during bolting, welding, and component placement. In a space that dense, without the ability to feel what is happening at the tool tip, the risk of damaging adjacent components or the vessel structure itself would be unacceptably high.

Godzilla’s role through the coming months is to test these tools on mockups that replicate the geometry and interfaces of the in-vessel environment. One tool currently being validated is a prototype tool changer, designed to let assembly robots switch between more than 30 different end effectors, covering handling, bolting, welding, inspection, and cutting operations, without stopping work for manual reconfiguration.

On site, two full-scale steel mockups, each representing one third of the vacuum vessel, are being set up to let operators and robots rehearse the actual assembly sequences before touching the real machine. One is already installed in the former Cryostat Workshop. The adjacent building extension, currently under construction, will house the second, which will accommodate a blanket assembly transporter and the heavy equipment needed to ferry and position blanket modules.

When the full sequence eventually begins, it will run 24 hours a day, six days a week, for an anticipated two years.

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