No. Used CANDU nuclear fuel is not a liquid or a gas – it is a stable solid. Under Canadian and international regulations, it is not classified as flammable, explosive or fissile material.
Canada's Used Nuclear Fuel
Used CANDU fuel generates some heat from radioactive decay. However, when used fuel is moved to the repository, it will have cooled for several years in an interim storage facility. It can be air-cooled and will not generate enough heat to melt.
Used nuclear fuel pellets are made from uranium dioxide powder, baked in a furnace to produce a hard, high-density ceramic. Ceramics do not readily dissolve in water and are resistant to high temperatures.
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Used Nuclear Fuel