A robot dog has been sent into a potentially hazardous area of a nuclear power site to switch back on a mothballed piece of equipment.

The four-legged machine — called Spot — reactivated a crane needed for lifting containers of waste at Dounreay near Thurso.

Due to safety restrictions, workers are not allowed to go near a switchboard to power up the machine. The crane had not been operational for about two years.

Spot has an attachment that allowed it to grip a short pole which it used to push the “on” button and start the crane.

Dounreay was opened 70 years ago as an experimental nuclear power site and is now being decommissioned and the site shutdown.

Engineers from the Robotics and Artificial Intelligence Collaboration, which involves the University of Manchester, worked on the solution to powering up the crane.

A week of trials was held in a storeroom using a mock-up switchboard before Spot was deployed inside part of Dounreay called the fuel cycle area.

Nuclear Restoration Services (NRS), which runs the site, said there was an audible “clunk” noise when the switch was flipped.