On Friday, Eadon Consulting completed the design of an overhead travelling crane for use in a nuclear decommissioning role, culminating in the issue of detailed manufacturing drawings, substantiation calculations and other documentation.

Due to radioactive contamination in the area where the crane will carry out most of its lifting operations, no personnel are able to enter once work has started. Therefore, a key requirement of the design was to provide a reliable means of recovering the crane into the maintenance cell where it could be decontaminated and repaired if necessary. The hoist gearbox is equipped with an auxiliary input, which can be driven by hand using a tool deployed through strategically positioned ports in the ceiling above the crane. This allows manual raising and lowering of the suspended load in order to deposit it in a safe position. A pair of manually operated back-up winches can then be used for long-travel motion to tow the crab back into the maintenance cell.

Space was another key limitation of the design: the need to interface with a pair of shield doors meant that only a small aperture was available to route cables and recovery ropes to the crab. In addition, the maintenance cell is cramped, with only limited access available to the top of the crab. The hoist was slung underneath the crab in order to maximise the accessibility of items that could feasibly require maintenance or repair.

We are now looking forward to seeing how manufacture and testing progresses in the coming months before it is put into service on site.