How is radioactive waste managed now - High Level Waste (HLW)
Store for packaged HLW canisters
Cutaway showing simulated vitrified
HLW in stainless steel canister
At Sellafield high level liquid waste is being incorporated into borosilicate glass, using a process called vitrification. The waste is heated to dryness leaving a fine powder, which is mixed with crushed glass in a furnace to produce a molten product incorporating the waste. This is then poured into stainless steel canisters, which hold approximately 150 litres, and a stainless steel lid is welded on.
Fresh waste from reprocessing is being blended with existing stored liquid waste and vitrified to a programme that maintains liquid waste stock levels within a specification issued by the Health and Safety Executive.
To date nearly 770 cubic metres of vitrified HLW have been produced, and the resulting 5,100 canisters placed in a modern, engineered air-cooled store pending a disposal route being available in the UK (go to What is the long-term solution - Higher activity waste).
Current practice is for vitrified HLW to be stored for at least 50 years before disposal. This allows a significant proportion of the radioactivity to decay away, for the waste to become cooler, and so make it easier to transport and dispose of - this makes long-term management less complex.
