A new plasma furnace system that can reduce the volume of nuclear intermediate level waste (ILW) by up to 90% could save the nuclear industry billions in waste storage costs, says Costain.
ILW results from nuclear waste management and decommissioning, and includes materials such as radioactive sludge and contaminated equipment. By reducing the volume of ILW the cost of packaging and storing the waste materials is minimised.
To trial the technology Costain collaborated with waste management firm Tectronics to adapt and enhance its existing plasma furnace technology to vitrify ILW. Tectronics built test facilities at Swindon over two years, with the trials taking two months.
The furnace operates at around 1000⁰C to 1400°C, taking between six and 12 hours to reduce waste to a glass-like substance.
Organic and carbonaceous material in the ILW is vaporised by the extreme heat produced by the plasma torches. This waste gas is cleaned via a filtration process and released, with any secondary waste collected from filtration fed back into the reaction chamber of the furnace for vitrification.
The inorganic material in the ILW, together with additives that reduce its melting point and increase fluidity, forms a pool of melted material in a water-cooled container. The material is cooled to form a stable, vitrified waste.
The solid material will be physically and chemically stable over thousands of years and, importantly, has demonstrated very low levels of leachability.
Costain said that the ability to greatly reduce the volume of ILW would “immediately ease the burden on the UK’s waste storage facilities” and could mean “considerable savings”, both in building future storage areas and in other areas of ILW treatment. Costain believes the technology could save the nuclear industry billions of pounds over the coming decades, with the added possibility of income through sale of the technology abroad.
Bryony Livesey, Costain's head of technology and consultancy, said: “We are now consulting with the nuclear industry on what the next steps should be. We’re seeking to develop this further.”
She added: “With the UK’s nuclear decommissioning process set to speed up in the near future, the project has enormous potential, both for the UK and globally.”
The project was supported by Innovate UK, the Department of Energy and Climate Change and the Nuclear Decommissioning Authority (NDA).