A project to assess and trial remote handling maintenance on tokamak components – similar to those which will be inside ITER – has seen experts visit UKAEA to assess the work.
The ITER Robotics Test Facility (IRTF) project – coordinated by Mickael Thery from RACE – saw the workhall of K3 filled with a mix of remote handling maintenance equipment.
In February, representatives from ITER visited to study the tools and mock up test rigs and to find out more details from the engineers involved in the 12 month-long project.
The project related firstly to maintenance activities around the tokamak and were focused on the vacuum flanges which are widely used around the ITER machine. It will be necessary to disconnect these flanges in order to remove components for maintenance.
The second aspect which the IRTF team demonstrated was the feasibility of remotely cutting and welding small bore pipes which are the source of cooling to the diagnostic first wall.
Remote capability will be needed for maintenance of ITER regarding tasks such as the replacing of a port plug. Once removed, the components are transferred to the hot cell facility ahead of either maintenance work or replacing them.
This use of remote maintenance mitigates the risk of exposing humans to radioactive parts of the vessel. In addition to a component’s removal, the project was also required to show that replacement of components does not compromise the integrity of the vacuum.
Remote work is performed using a Master-Slave Manipulator (MSM) – one of the most common remote handling tools in the nuclear industry. An MSM has two arms, namely a master arm and a slave arm. The latter is placed in the radioactive or ‘hot’ area, and the master arm in the operating area. The arms are on either side of a thick wall but connected with a tube; this allows the slave arm to reproduce the movement of the master arm. A secondary option to this is a powered manipulator where the arms are connected electronically and not mechanically – similar to MASCOT. This means the master arms can be located up to 100 meters away from the slave arms.
One of the key tasks for the manipulator was to successfully unfasten and fasten the bolts holding a flange together. In addition, it was required to undertake small bore pipe cutting and welding. A multipurpose tool is needed to perform such a range of operations, including the cutting and welding of pipes, and the lifting, rotating, tilting and fastening of components.
Mickael Thery, Project Manager for IRTF, said the project was well received: “The tasks we were demonstrating as part of the IRTF remote maintenance were essential to make sure similar work to this can be carried out safely, and remotely, on ITER.
“Our engineers have worked extremely hard to meet the challenges of demonstrating the relevant remote maintenance over the last few months, and it was satisfying to be able to demonstrate to ITER the success of this trial project.”