Design of an overhead crane for the ITER NB cell remote handling maintenance operations

In the neutral beam cell of ITER all the maintenance operations on the neutral beam components (BLCʹs) must be performed by an overhead crane of large payload capability (30–50 tonnes). A crane system is presented consisting of a monorail, a carriage, and a lifting mechanism. The monorail must give access to the BLCʹs in the beam line vessel, the front components connecting the NB vessel with the Tokamak, and a storage area at the north end of the NB cell. Rail switching points are required at the intersections between radial and toroidal branches. A translational switching mechanism is proposed. The crane carriage consists of two independent sub-carriages, each composed of four wheels. A set of four secondary wheels attached to the main carriage prevents the crane tilting due to the CoG misalignment of some loads. The elevation system proposed consists of an electromechanical crane of four independent drums and 50 tonnes payload. In parallel with the crane design, a logistics and space availability study has been carried out, leading to the detection of clearance or transport problems that could be taken into account in the final crane design.