Finnish researchers have managed to replace a divertor cassette of a simulated ITER fusion reactor using a remotely controlled maintenance capability for the first time, marking an important milestone on the way towards the launch of the world's largest fusion experiment.
The operation carried out at the VTT Technical Research Centre of Finland saw a team at the VTT’s Divertor Test Platform replace the cassette entirely from the control room with the assistance of virtual models and cameras.
The Divertor Test Platform, a full scale mock-up of the bottom part of the fusion reactor, also known as the divertor, is about 20 metres long and weighs approximately 65 tonnes. It is fitted with 54 divertor cassettes – giant ashtrays designed to collect hot ashes and impurities from the fusion reaction. Each of the 3.4m x 2.3m x 0.6m cassettes weighing 10 tonnes has to be handled with a precision of a few millimetres.
The cassettes are installed via three separate maintenance tunnels using a robot and a manipulator. When it is time to remove the divertors, they are unlocked and detached from the ITER reactor chamber, placed in a transport container and removed to be processed in a 'hot cell' facility.
Although needed only three times throughout the designed 20-year lifetime of the reactor, the replacement operation is critical for a safe progress of the experiment.
With extremely hot temperatures reaching up to one hundred million degrees centigrade, all inspection and maintenance on the reactor will have to be performed remotely.
The team developing the remote control capabilities for ITER believes the technology developed throughout the project will find a wide range of applications in other industrial sectors. Such capabilities can be handy in all locations with difficult access for human workers including underground operations or those in space.