Bradwell Nuclear Power StationFED Retrieval Crane

To facilitate the decommissioning of part of Bradwell Nuclear Power Station, SCX Special Projects provided a semi-automatic FED (Fuel Element Debris) Retrieval Crane.

The crane facilitates waste handling throughout the plant: removing drums containing waste from a cross-site transporter and transporting them to and from a tipper and sorting table; transferring baskets containing the sorted waste to and from a dissolution vessel; and stacking trays containing the remaining waste following dissolution into a Mosaic ready for export.

The crane control system design utilises semi-automatic positional control. The operator is able to select one of 19 pre-determined automatic pathways via the push of a button, within pre-set sequence parameters. Manual operation then enables the operator to accurately couple the crane with each of the various load types.

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Semi-automatic control is facilitated from a SCADA system connected to the crane’s PLC controller over a dedicated communications network, supported by safety interlocks and a dedicated hardwired Engineered Protection System. The operator is simply required to select the required

crane sequence from the screen menu.

In semi-automatic mode, the crane travels at 4m/min on the long travel motion and 2m/min on both cross travel and hoisting, but is

restricted to 0.2m/min to ensure fine control when in manual mode.

The modified standard hook block features a pintle adapter, enabling the crane to couple with and lift the drum grab, baskets and trays.

The use of manual control for coupling the modified hook block and pintle to the loads, overcomes any positional inaccuracies that may occur when the loads are manipulated by the sorting machinery or cross-site transporter.

The control desk is remotely located in a separate building to ensure containment and the operations are monitored by CCTV. Additional CCTV cameras mounted to the underside of the hoist provide the operator with the ideal view of the pintle and load for accurate positioning.

Bullet systems provide independent recovery on both the cross-travel and long travel motions. Using a wire rope and winch arrangement, the bullet triggers a paddle to release the crane’s brakes and then interlocks to recover it back to a safe area.

The MotoSuiveur (MS) hoist safety system mounted directly to the drum provides independent failsafe protection against overload, overspeed and load drop, as well as incorporating the MS units own independent hoist recovery option.

A rotary encoder and switch mounted on the MS unit provides continual feedback on the position of the hoist.