Hunterston Nuclear Power Station – Wet ILW sludge retrieval systems

SCX designed and installed a range of handling solutions for the retrieval and handling of intermediate level waste at Hunterston Nuclear Power Station in Scotland.

The Challenge

The Magnox plant at Hunterston required high-integrity mechanical handling solutions for the safe and reliable retrieval, manipulation, packaging and transport of Intermediate Level Waste (ILW).

Various waste boxes and drums, each posing their own unique challenges, needed to be handled in a manner that met demanding Safety Cases. And all in processing environments that carry operator exposure risks, so automation and remote control was a prerequisite.

The Solution

SCX designed, built, tested and installed three handling solutions, each tailored to the differing requirements of Hunterston’s ILW packages and their processing environments.

Each crane has a bespoke motorised rotating grapple, with one carrying a remote-controlled mast for entering ILW sludge ponds to safely retrieve and package waste materials. The cranes demonstrate our capability to engineer and deliver safe, reliable handling solutions for nuclear licensed sites.

Technical Details

Precision positioning

The bespoke grapple engages with either ILW boxes or drums via four twist lock sockets

The package is then held in a preset position for swabbing, then lowered into a cross-site transporter vehicle for transfer to the storage facility

Limit switches, load cells, proximity switches and photocells provide advanced EC&I monitoring and millimetre precision

Ensuring repeatable accuracy

Fine electrical control, precise mechanical design and laser positioning ensure millimetre accuracy

Our bespoke grapple design interfaces with either Nirex boxes or drums, complete with a sophisticated locking detection system with visual confirmation flags for safety

The system uses semi-automated positioning presets, all controlled remotely via a CCTV-fed desk

Thoughtful engineering

The innovative latching and rotating grapple engages via twist locks into a common socket interface used on a range of ILW packages

The chassis of the crab is carefully planned to mount cabinets and cabling, and to provide easy maintenance access

SCX’s EC&I design employs load cells, encoders and limit switches, sending real time data back to the operator and detecting potential safety issues

Meeting the challenge

SCX engineered four bespoke systems for Hunterston’s wet ILW handling:

a 10-tonne main hoist with a 2-tonne auxiliary hoist;
a 3.2-tonne, crane-mounted sludge retrieval pumping rig;
a rig cleaning station;
an ILW box encapsulation process.

The systems work together along a 14-metre shielded ‘canyon’ to retrieve waste, fill and seal the ILW packages, then position them for site transfer

Fit-for-purpose solutions

Cranes for waste handling require shorter design working lives – five years in this case – enabling us to create more cost-effective, fit-for-purpose solutions

This is the main hoist for solid ILW handling, with a 10-tonne SWL, and four wire ropes to give true vertical lift

A 7-metre height of lift is inverter-controlled at speeds of 0.5 or 5m/min, long travel is 1 or 10m/min, while cross travel is 0.5m/min

Full system thinking

The process of packaging wet ILW materials through multiple, connected mechanical handling stages requires SCX’s ‘full system thinking’ approach

Interfaces between each stage require careful engineering to ensure smooth transitions and risk-free operation

Preset positions are detected and interlocked with neighbouring stages to prevent accidental movements

A tried and tested design

This latest design is an evolution of the solid and wet ILW hoists, giving true vertical lift and a 12-tonne SWL

With a 12-metre height of lift, raise speeds are 0.5 to 5m/min with long travel speeds of 1 to 10m/min

Inverter-controlled movements deliver smooth acceleration and deceleration, reducing shock loads and sway

Control from a safe distance

The crane is operated remotely via an HMI, which provides a CCTV feed and control over a range of semi-automated preset positions

Radio pendants are provided for closer control and maintenance, with operations protected by key interlocks

Diverse recovery mechanisms allow the load to be secured event in the event of a hoist failure or loss of power

Safety always first

The cranes are able to be recovered remotely in the event of a hoist or power failure, ensuring that no personnel need to access the area when an ILW package is present

Interlocks are used to restrict hoist and grapple operations outside of defined safe areas

Even with the complete failure of one rope, the load is held secure and level

Explore more specialist handling solutions from SCX

Hunterston Nuclear Power Station – Wet ILW sludge retrieval systems

The Challenge

The Solution

Technical Details

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