ITER’s Vacuum Vessel, the massive steel container housing the fusion reaction, features a series of openings known as ports. There are 44 of them around the machine, at three different levels: 18 upper ports, 17 equatorial and 9 lower. These spaces provide a window into the heart of the machine for auxiliary systems like diagnostics, heating, maintenance or fuelling. Each port will be sealed with a plug, custom-made to protect and anchor the different equipment.
Transferring and inserting the plugs in and out of the machine is a heavy, delicate operation. Because the port plugs will ultimately become radioactive, they will be carried inside double-door casks, which resemble freight containers and can weigh up to 100 tonnes when fully loaded.
Europe is responsible for providing the Cask and Plug Remote Handling System. Fusion for Energy (F4E) has been working with various partners to develop this technology, which will initially come into play during the first assembly of ITER. In late 2023, F4E signed a contract with Ansaldo Nucleare for manufacturing the machines that make up the system for this first phase. One of them is the Cask Transport System (CTS), a semi-automated vehicle designed to carry the plugs from the Assembly Hall to the upper and equatorial port through the galleries surrounding the reactor.
Ansaldo Nucleare entrusted the CTS fabrication to Solving, a Finnish firm specialising in handling systems for heavy loads. Their clients range from the aviation to the steel or energy industries. But working for ITER was a first for them. “We collaborated closely with our suppliers from the outset, refining the design to ensure the machine would comply with the strict performance needs of ITER,” recounts Caroline Dremel, F4E Technical Officer. Besides carrying a payload of 80 tonnes, the CTS must manoeuvre through tight spaces with flawless accuracy.
How will it navigate the obstacles along its course? The CTS, an eight-meter-long wheeled platform, can be steered in full-manual or semi-manual mode with a remote controller. In areas with limited access, the machine will follow a high-contrast line marked on the floor thanks to built-in optical sensors.
The Final Acceptance Tests (FAT) took place last week, after Solving completed the vehicle’s assembly. Teams from F4E, ITER Organization and Ansaldo Nucleare travelled to the workshop in Finland to witness them. The CTS demonstrated its heavy-weight capacity by lifting an 80-tonne dummy load in place of a cask. The machine then moved through a fenced corridor shaped like the ITER galleries, mimicking the operations to install or remove the plugs from the port cell.
The teams on site were delighted to see years of work rewarded in a smooth dry run. Matias Nygård, Sales Manager at Solving, said: “The success of the tests makes us very proud. Solving has been involved in the project since the preliminary design stage, back in 2019. We are a small company and therefore it’s an honour to be involved in a huge project like ITER.”
“The huge efforts that we and our partners put in have come to fruition,” celebrates Darren Locke, F4E Project Manager. “But its value goes beyond this project. We have gained a wealth of know-how that will help future remote handling systems procured by F4E or the ITER Organization,” he adds.
In the coming months, the CTS will be shipped to Italy so Ansaldo Nucleare can take over: “Following the completion of the FAT and the resolution of all pending items, we will carry out tests integrating the CTS with the Equatorial Port Plug machine, which is currently undergoing assembly and internal testing,” described Emanuele Verdesio, Project Manager for Ansaldo Nucleare. Subsequently, the same integration will take place with the CTS and the similar Upper Port Plug machine.
The plan is to deliver the complete system by the end of the year. Once at ITER, the machines will take part in further rehearsals, including at the port plug test facility, which will soon be ready onsite. At a later stage, F4E will also provide a nuclear-grade version of the system, to replace and maintain plugs during research operation.
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