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Bâtiment PF Atelier Cryostat Le Siège d'ITER Fosse du Tokamak Fondations du Tokamak Bâtiment d'Assemblage Bâtiment et emprise Assemblage de la machine Métrologie optique Des outils dédiés | ||||||||||||||
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 Operators Vesa Hämäläinen (left) and Jaakko Karjalainen observe—and if necessary steer—the moves of the actuated machine during a test run at VTT. The next morning the mercury hasn't budged. Dressed for an arctic expedition and equipped with tires that have spikes, the group of technical officers from the ITER Organization drives through Tampere for twenty minutes to reach VTT, the Technical Research Centre of Finland. It is here that ITER's European Domestic Agency has built the test-stand for the ITER Divertor, the component within the machine that will have to face the highest thermal loads during operations—the heat flux will be up to 20 MW/m². The fact that, of all the places in the world, the divertor is being tested here in Europe's "icehouse" is the standing joke. Engineer Karoliina Saminen welcomes the group by saying, "Yes, here in Tampere we are used to extreme conditions!"
On this morning in early February, the group is present to witness, once again, what "millimetre precision" truly means. As an electrical servo-motor actuates the giant structure, the DTP Cassette Multi Mover (CMM) transports a divertor cassette (3.5 m long x 2.5 m high) through the remote handling port and into the ITER-scale vacuum chamber. While the CMM is bedded on rails, the actual cassette is only county levered by a special end effector. Transport must be executed with pinpoint accuracy because the trajectory is such that delicate plasma-facing elements of the cassette have to pass within a couple of centimetres of the vacuum vessel surfaces. The cassette, which has been preloaded with a force of ten tons to withstand the electromagnetic forces acting on it, needs to be tilted, returned to vertical position, and pushed to one side before its knuckle can lock into its final position. "This is what I call an acrobatic design," says engineer Alex Martin, who has witnessed this procedure many times—and each time with fascination.  Inside the giant: the divertor cassette approaching the Vacuum Vessel through the remote handling port. The DTP test-stand is operated from a control room within the huge hall at VTT. From there, operators like Vesa Hämäläinen and Jaakko Karjalainen can observe and direct the moves of the actuated machine during the test runs. Operators rely upon virtual reality models, imitating future ITER operation when the remote handling operations will be conducted from a room located far from the vacuum chamber—and this with millimetre accuracy. Failure is not an option! Behind their commands, Vesa and Jaakko are busy calibrating and testing the software and the camera viewing systems that will help them "to push the camel through the eye of a needle" as this difficult task was once described.  There is not much headroom between the plasma-facing components and the vacuum vessel when the 10-ton divertor cassette is moved into position. Click to watch the ITER video Like pushing a camel through the eye of a needle. Click again to watch VTT-produced video shot of remote operations at the DTP2. << return to Newsline #170 |
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