Trawsfynydd Nuclear Power Station - MOTS System for Low-Level Waste Handling

Aerospace, Nuclear & Defence

The challenge

Trawsfynydd’s Sludge Solidification Building is a central part of the site’s decommissioning efforts where active waste is encapsulated into 3m³ Radioactive Waste Management (RWM) drums.

Safe handling of the drum linings, lids, and secondary containment vessels (SCV) necessitated a remotely operated nuclear handling solution incorporating a bespoke lifting grapple that could transport payloads from the process building, onto dedicated transfer vehicles for long-term storage elsewhere.

The solution

SCX supplied a modified-off-the-shelf (MOTS) system with a purpose-built latch plate that attaches itself via electrically operated twistlocks. This is operated in a control room through static mounted CCTV cameras that provide sight of procedures.

The solution has been designed and tested to cope with the high number of stops and starts associated with heavy duty industrial applications and benefits from increased reliability through use of standardised components.

Mitigating unwanted motion

  • The 10-tonne SWL overhead crane provides 9 metres of true vertical lift for the bespoke grab and is fitted with ultimate raise and lower limit switches

  • A fail-safe hoist brake arrangement sees the brake mounted directly onto the gearbox rather than the rear of the motors

  • Load cells are incorporated to disable the lowering function when a no load condition is detected on the ropes


Do the twist(lock)

  • The grab attaches to RWM drums via electrical twistlock devices, that prevent lifting if not fully engaged or released
  • The twistlocks can be driven from one of two linear  actuators that rotate on a central cam
  • The engage and disengage motions of the linear actuators are controlled by proximity limit switches, only operating when a no load condition is detected on the ropes and the lifting frame is secured


Mission control

  • The control system is tailored specifically to Trawsfynydd’s needs was developed in consultation with Magnox personnel
  • Ultimate travel stop limits prevent operators from accidentally driving the system beyond its safe envelope, with automatic slowdown on approach
  • All the terminals and electrical equipment within the control console have finger protection to a minimum of IP2X with the enclosure IP rated to at least IP54


Let's talk more about nuclear handling solutions

The nuclear sector demands levels of safety and integrity that requires special high-integrity equipment. As safety cases are revised and become increasingly demanding, handling solutions must evolve to keep up and remain fit-for-purpose.

We design some of the safest, most reliable mechanical handling systems in the sector. Talk to us today and discover the solution to your lifting and mechanical handling challenges.

Call us on +44 114 262 6199, email us at, or complete the contact form below and we'll be in touch.

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SCX Special Projects Ltd

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

t:  +44 (0)114 262 6199