Hunterston Nuclear SAWBR Facility - ILW Nirex Box Handling Crane

SCX Special Projects designed and installed a 10 tonne crane for handling 3m3 Nirex boxes containing intermediate level waste (ILW) at the SAWBR (Solid Active Waste Building Retrieval) facility at Hunterston A Nuclear Power Station in Scotland.

The empty Nirex boxes arrive at the building on an import wagon, where they must then be transported into and around the facility through a series of shield doors. They are then filled, sealed, swabbed and, once verified free of external contamination, must be accurately deposited into a cross-site transport (XST) vehicle in order to be removed from the facility and taken to a purpose built ILW store.

This project enabled SCX Special Projects to develop a modular crane design for use in the handling of nuclear ILW packages in both process plant applications and long-term storage solutions throughout the nuclear decommissioning arena. The system incorporates integrated back-up recovery systems for all motions to ensure safe package delivery in the unlikely event of an operations failure.

Primary and secondary braked motors of a nuclear crane

The hoist is fitted with primary and secondary braked motors. The brake systems are fitted with back-up actuators to ensure that in the event of failure of the primary hoisting system, the load can still be appropriately set down prior to removal of the crane from containment for maintenance.

Absolute laser measurement provides a positional resolution of ±1mm, and the installation incorporates a recovery winch system so it can be rescued from the containment area in the event of long travel failure.

Specially designed nuclear crane lifting grapple with four twist-locks

The specially designed lifting grapple, created by SCX Special Projects for the handing of both 3m3 Nirex ILW boxes and drums, incorporates four twist-locks that engage with the boxes. A main ‘floating’ actuator controls the twist locks, but in the event of a failure, a secondary recovery actuator overrides the first, ensuring the load can always be set down before the system is retrieved from the containment area. Four plungers detect whether the grapple is correctly seated before the twist locks can engage.

Visual flag indicators on top of the grapple plate for manual verification in the case of a malfunction

Operation of the grapple is fully remote and controlled and monitored by a series of limit and proximity switches. Both the plungers and twist locks activate visual flag indicators on the top of the grapple plate so that should the automation sensors malfunction, the operator can manually verify the positional status and use the override function to continue operation of the crane.

Electrical controls in an enclosure with radio control for a nuclear crane.

The crane is programmed to operate automatically from signals fed through from existing upstream control systems, whilst absolute encoders fully map the operating envelope of the crane and provide continuous positional feedback to the upstream controls. The entire process can be viewed from the safety of a remote control room complete with CCTV, whilst a radio remote controller enables the manual override operation for maintenance.

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SCX Special Projects Ltd

Roman Ridge Road, Sheffield, S9 1GA, United Kingdom

t:  +44 (0)114 262 6199