Land and Marine has resumed its search of the seabed near Dounreay for "significant" fragments of nuclear fuel.
The company is working with specialist radiation sub-contractor Nuvia to recover the remains of historic discharges from the site.
Its return to the seabed marks the third consecutive year of full-scale offshore clean-up and the fourth involving remotely-operated equipment on the seabed.
The 1500-tonne barge LM Constructor is now deployed off the site, providing a recovery platform for an underwater ROV and a team working around the clock for the rest of the summer.
The ROV is fitted with systems capable of detecting and recovering particles, similar in size to a grain of sand, in an area of seabed equivalent to 600 Olypmic swimming pools.
DSRL senior project manager Bill Thomson said this year’s work aims to:
• complete coverage of the 60-hectare plume where “significant” particles are concentrated
• repeat the most affected areas to recover more particles and understand better how the higher-activity particles have moved in the sediment
• gain more information about the spatial extent of the plume and drop-off rates at depth and distance.