Amec Foster Wheeler, J Gunn and Sons and Street Cranes Special Projects Ltd will be involved in the design and construction of the facility.

Amec will design the waste store while J Gunn and Street Crane will handle the site enabling works and drum handling hoist design respectively.

Once finished, the storage unit will have capacity for up to 2,800 drums of radioactive waste.

The 500-litre drums contain raffinate – a highly radioactive nuclear byproduct – which is mixed with cement and sealed at the site’s cementing plant.

The decommissioning firm has estimated that 1,200 cubic metres of raffinate were produced at the plant before it stopped reprocessing spent nuclear fuels in 1996, which was stored in 21 underground tanks.

Meanwhile, other historic wastes in the form of radioactive solids, liquids and sludge will also be processed at the cementation plant for storage.

Highland Council granted planning permission for the store in March.

Leigh Wakefield, business unit director for Amec Foster Wheeler’s Clean Energy business, said: “The decommissioning of the Dounreay site is an extremely demanding and complex process and one that is well suited to the skills we have in Amec Foster Wheeler.

“The design of this state-of-the-art facility is a key element in the decommissioning strategy of the site and one that we are looking forward to delivering for this important client.”

Construction is expected to be complete by early 2018.