Nuclear Power - vitrification

Vitrification (from Latin vitreum, "glass" ) is a process that allows the conversion of waste into a large glass block.

The waste is mixed with glass-forming chemicals in a 'melter' to form molten glass that then is poured into in canisters, solidifying and immobilizing the waste. The final waste form resembles obsidian (a black volcanic glass) and is a non-leaching, durable material that effectively traps the waste inside.

It is believed that the waste can be stored for relatively long periods in this form without concern for air or groundwater contamination. Pacific Northwest National Labs says that "Vitrification locks dangerous materials into a stable glass form that will last for thousands of years."

The nuclear power plant at Sellafield has a vitrification plant that enables reprocessed high level waste to be solidified into such glass blocks. These are then sealed in stainless steel cans and placed in a carefully controlled storage facility.