Contract awarded for Dounreay NaK removal

29 August 2018

Nuvia (UK) has won a “multi-million-pound” contract from Dounreay Site Restoration Limited (DSRL) to design, procure, install and commission plant and equipment to remove the residual sodium-potassium (NaK) remaining in the Dounreay Fast Reactor’s (DFR) piping network. The DFR started operating in 1959 using sodium-potassium coolant.

The Dounreay Fast Reactor (Image: DSRL)

Nuvia said today that the NaK is to be removed using an existing Water Vapour Nitrogen process - “essentially steam” - that will react with the residue, producing sodium hydroxide, potassium hydroxide and hydrogen. The resultant products will be collected and processed using existing gas filtration systems and the existing Ion Exchange Plant to make them safe for disposal, the company said.

David Craig, Nuvia’s Dounreay business manager, said: “This is an important contract win. Over many years Nuvia has a number of decommissioning activities at DFR. We are delighted to continue our relationship. This is an excellent opportunity to pass some of our knowledge and expertise onto the next generation”.

The works will be engineered in Nuvia’s design offices, from where the first stage procurement and manufacturing of pipework and equipment will also be managed. Installation and commissioning will be undertaken on the Dounreay site and will be managed utilising Nuvia’s local staff with support from the local Caithness and Sutherland supply chain.

The contract started last month and is to be completed within three years.

The dome-shaped experimental reactor closed in 1977 and then most of the core fuel was removed, but follow-up work stopped when some of the metallic casings in the zone surrounding the core were found to be swollen and jammed. According to the Nuclear Decommissiong Authority (NDA), which is responsible for the DFR, almost 1000, or two-thirds of the total, were left in place.

The NDA says decommissioning the 50-year-old reactor is one of the most technically challenging projects in its estate and removing the breeder elements has been a top priority. The removal work is expected to take fewer than three years, it said in September last year, and dismantling of the landmark reactor can then begin.

Researched and written by World Nuclear News