Work has started to make safe one of the most hazardous materials left at Dounreay.
Highly radioactive liquid, known as raffinate, has been stored in tanks for around 20 years after being produced as a by-product of Prototype Fast Reactor (PFR) fuel reprocessing. Now a project to reduce the risk is underway with more than 30 drums, totalling 15,000 litres, filled with solid waste as part of an initial commissioning process.
Project Manager Stuart Andrew explained: “One reason this material is so hazardous is because it is in a mobile, liquid form. Now we are taking an exact amount from each tank to create a consistent blend. It is then mixed with cement, pulverised fuel ash and lime powders to create a solid, passively safe waste package.”
Dounreay Waste Director Sam Usher added: “With similar liquid waste from two of Dounreay’s reactors already made safe, this is the last piece of the jigsaw and probably our highest single remaining hazard. Safely and compliantly creating the first solid waste drums is a huge achievement for the team and a major step forward as we deal with the site’s legacy hazards.”
It has taken almost 2 years to modify plant and equipment after the same facilities were used to process more than 230m³ of Dounreay Fast Reactor raffinate until 2016. Now up to 100 drums, each taking around 70 minutes to be mixed in cement, are expected to be produced in the next few months as part of the first phase of this programme. All PFR raffinate is expected to have been processed within the next 5 years.
Mark Raffle, Lead Programme Manager from the Nuclear Decommissioning Authority, said: “Immobilisation of this highly radioactive liquid will be a significant step towards reducing the remaining hazards at Dounreay. Completion of this work will enable decommissioning of the major facility where the material is currently stored, moving the site closer towards its interim end state.”
Companies are currently being asked to express an interest in a contract to construct an extension to the facility where the waste packages will be stored in accordance with the Scottish Government’s higher activity radioactive waste policy. The multi-million pound construction project is expected to begin later this year.
Dounreay, once the UK’s centre of fast reactor research, is now Scotland’s largest nuclear decommissioning project and is widely recognised as Europe’s most complex nuclear closure programme. The work is being delivered by Dounreay Site Restoration Limited, a company owned by Cavendish Dounreay Partnership, on behalf of the Nuclear Decommissioning Authority.