VTT has reached an important objective in
the development of ITER fusion reactor remote control, when the divertor
cassette was replaced for the first time using remote control in the research
facility for remote controlled maintenance. This operation is one of the most
demanding measures in the forthcoming ITER fusion reactor, the construction of
which is proceeding rapidly in Gadarache, Southern France.
The requirements for the technologies used in ITER, are high, since they are
used to control the fusion plasma burning at a temperature of hundred million
degrees centigrade. Once the ITER comes into use, its core is activated when
bombed by neutrons. Therefore, all maintenance, inspection and repair measures
are performed using remote operation.
Located in the lower part of the ITER reactor chamber, the 54 cassettes of the
reactor component, or the divertor, measuring 3.4 m x 2.3 m x 0.6 m and
weighing approximately 10 tonnes each, need to be handled at tolerances of a
few millimetres. The divertor cassette is like a giant ashtray, into which the
hot ashes and impurities settle.
In remote operation, the 54 divertor 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. According to the plan, the parts will be replaced three times
during the 20-year service life of the reactor.
For the cassette replacement operation, the lights of the Divertor Test
Platform, or the DTP2 facility located in a VTT research facility were dimmed
to correspond with the prevailing conditions in ITER, and the whole operation
was performed from a control room with the assistance of virtual models and
camera views. The DTP2 is a full scale mock-up of the bottom part of the
fusion reactor, its so-called divertor area. The actual test platform is
approximately 20 metres long and weighs some 65 tonnes.
The successful operation was also witnessed by representatives from Fusion for
Energy (F4E), responsible for European coordination of the ITER project, and
also from the ITER organisation. Work related to remote operation and
maintenance operations has not yet reached completion and will continue.
Components for the reactor are being produced in different parts of the world.
In Finland, VTT collaborates with Tampere University of Technology to perform
R&D related to remote maintenance of the ITER reactor divertor part.
In the ITER reactor maintenance, remote operation and virtual technologies
play a key role, and they have extensive opportunities for application in
other industrial sectors as well. Similar technologies are being used, for
example, on space flights and in underground operations. The system combines
robotics, advanced technological tools, powerful computers, and virtual