In an age where oil prices are soaring, fossil fuels are being depleted and carbon emissions are subject to ever more stringent regulation, the hunt for a sustainable and non-polluting power source is on. The holy grail of this quest is nuclear fusion – harvesting power from the same reaction that occurs in the sun to create light and warmth.
Scientists have been working to experimentally create the reaction for more than 50 years. In the laboratory, fusion involves forcing two isotopes of hydrogen, deuterium and tritium, to collide and fuse with each other and release substantial amounts of energy in the process. This is done in a machine known as a tokamak, which uses magnetic fields to contain and control the hot plasma that harbours the isotopes.
An international collaboration based in Cadarache, southern France, is hoping to prove that fusion can be a clean and sustainable source of power. Known as Iter, it is one of the world’s biggest engineering projects. This year sees it move into an exciting new phase. With many of the designs now finalised, components of the fusion machinery are starting to be manufactured, bringing nuclear fusion one step closer to reality.
At this stage, 75% of the procurement arrangements have been signed. Ken Blackler, head of the assembly and operations division of Iter, says: “Essentially we have handed the ball over to the domestic agencies now and are starting to sign contracts and, in some cases, move into the manufacturing phase for the major components.” Deals are in place for all the key parts of the Iter machine, including the vacuum vessel, the magnets and the buildings.
The remaining 25% of contracts will provide the auxiliary systems that are less urgent and have yet to be designed. These include systems for measuring, diagnostics and data remote handling. Deals for these will be signed within the next two years.
“Everything is running to schedule,” says Blackler. Excavations for the tokamak complex, which will house the Iter machine, have been dug and the concrete base mat has been poured into place. The seismic isolation pads, that will protect the building in the event of an earthquake, are essentially complete. Work is now focused on the retaining walls and anti-seismic bearings that are scheduled to be place by March.
In April, the concrete for the basement of the building will be poured into place. Meanwhile, the 12,000-square-metre building that will house the poloidal field coil-winding machinery is completed. Six horizontal superconducting coils, from eight to 24 metres in diameter, will sit on the outside of one of the magnet structures that stabilises the plasma. These coils are the biggest components of the Iter project. Five of them are too big to be transported in one piece, so will be manufactured on site in the winding building.
Now most of the contracts have been arranged, Iter is moving from the design phase to the industrial stage. Tenders are out for the construction of the remaining 35 buildings on the site. Over the next two years, Blackler’s team will be tendering a further 40 contracts for the assembly and installation of the Iter machine.
Some engineering support contracts have already been signed with UK companies, including Oxford Technologies – which specialises in remote handling equipment, Assystem UK and Amec. Assembly of the tokamak is due to start in 2015, with the installation of the associated plants beginning the year before. The device is set to be finished by 2019.
Licensing of the fusion device with the French nuclear authority has been one of the biggest challenges for the project. “Previously, fusion has always been an experimental device, where you have different constraints. But now we are classified as a nuclear device,” says Blackler. The maturation of the field has meant that safety has become a critical component of the design. “That’s a new thing for fusion,” he adds. Iter hopes to get the decree from the French government to go ahead this year.
As the project moves forward, new skills will be required on site. When the assembly area becomes active, staff skills will have to adjust accordingly. The recruitment emphasis will move from design engineers to installation engineers.