An area of seabed equivalent in size to more than 10 football pitches is to be monitored over the summer during the next phase of implementation of Dounreay’s particle recovery programme.
The work will be carried out by a locally-based company, Fathoms, using a remotely-operated vehicle, known as TROL, in water up to 30 metres deep.
It will scan 75,000 sq metres of seabed near the old effluent discharge outlet and retrieve particles detected in the sediment.
A demonstration exercise last summer recovered 55 particles from a nearby area.
“We are focussing on a seabed area of 7.5 hectares to the north and west of the old discharge outlet where independent experts have assessed the most radioactive particles are located," said Phil Cartwright, the project manager at Dounreay Site Restoration Ltd responsible for the work.
"Our objective is to reduce the number of particles on the seabed and provide information that will assist planning of work in future years.
“Once we have covered this area, we will review the results with the Scottish Environment Protection Agency and the independent Particles Retrieval Advisory Group, before deciding what further work may be necessary before the weather turns in the autumn.”
A separate area of seabed between the old diffuser and Sandside Bay will be surveyed before and after the clean-up to provide ‘baseline’ information. This will assist in understanding the effect of the clean-up on the movement of particles over the next few years.
The work in the main area off Dounreay will begin once the first of these surveys has been completed in the next few days.
Monitoring of nearby Sandside Beach and areas of the Dounreay foreshore will be enhanced during the offshore work.
Recent, valuable consultations with the head of the company that owns Sandside Estate, Mr Geoffrey Minter, have led to changes in the approach to deployment of the beach monitoring equipment. There is greater focus on the low-tide area, leading to improved coverage of the beach. The effect of the changes will be kept under review.
Three particles were detected on Monday, one on Tuesday and another on Wednesday. All lay within the range of radioactivity of particles previously found at Sandside.