Fusion factory: assembling Iter, the most complex machine ever built

My last visit to the site of Iter, the international project to develop and build the world’s largest ever nuclear fusion reactor and a model for the powerplant of prospective fusion power stations, was three years ago. Then, there was comparatively little to see on-site, as the foundations that will support the enormous weight of the fusion machine were still under construction, and the concrete had yet to be poured. The situation now is very different.

The theoretical and design aspects of the Iter ‘fusion machine’ — as it is known within the organisation — have largely been finalised, and the contracts for construction of its components farmed out among its member states. The remaining task, to piece all 10 million components together, is essentially a programme of mechanical, electrical and process engineering; but what a programme.

It will be the most complex machine ever built — an accolade that’s been held at various times in past decades by the Boeing 747, the Apollo command module, The US nuclear missile submarines, and the Large Hadron Collider. Because of the level of instrumentation and the need to comply with existing nuclear regulations, Iter is currently seen as likely to be the most complex fusion reactor ever built.