A GIANT robotic crane is to be used to remove dangerous radioactive waste from a pit at the Dounreay nuclear complex in Caithness.

The remote-controlled machine will reach down into the 214.5ft pit as work to clean inside the shaft is accelerated.

Tenders are being sought for two contracts to design, build and install the robotic apparatus. The work for Dounreay Site Restoration Limited (DSRL) is worth a total of about £4 million.

The pit at Dounreay was built in the 1950s, close to the shore of the Pentland Firth. Radioactive waste was disposed there for 18 years between 1959 to 1977, when an explosion halted the practice.

The executive team at Dounreay said in May that work on cleaning up the pit, which is covered by a massive bunker-like structure, would continue.

It has been estimated that costs would exceed £180m, and the project take until 2025 to complete.

The robotic crane and grabber, which will be lowered inside to collect waste, will need to be able to cope with a challenging environment.

The pit has been the subject of local legend, including the claim that one worker dropped his mother-in-law's ashes inside.