vitrifier

A vitrifier is a device or facility used to immobilize materials by vitrification, the process of turning them into a stable glass. In nuclear waste management, vitrifiers convert radioactive liquid wastes into borosilicate glass for long-term containment. The term can describe either the melting unit (melter) or the entire vitrification plant that performs the process.

In typical operation, the waste is pretreated to meet the glass-forming requirements and blended with glass-forming additives such as silica, boron oxide, and other oxides. The feed is fed into a high-temperature melter where it is melted at approximately 1,100 to 1,150°C. The molten glass is then poured into stainless steel canisters and cooled to form a solid waste form. The glass matrix encapsulates radionuclides, providing low leachability and protection against diffusion over decades to millennia.

Vitrifiers include different melter technologies, such as Joule-heated ceramic melters and induction melters. Vitrification plants incorporate off-gas treatment systems to remove volatile radionuclides and protect the environment. They can operate in batch or continuous modes and require remote handling and shielding to ensure safety.

Vitrification is used at facilities worldwide to stabilize high-level and some intermediate-level wastes. Examples include plants in operating or former reprocessing sites, where the resulting glass waste form is designed for disposal in geological repositories and subject to stringent regulatory oversight. The approach aims to minimize long-term environmental risk by converting liquid waste into a durable, leach-resistant solid.