The design and operation of a 100-kg/h electric melter for nuclear waste vitrification

The vitrification of simulated nuclear waste calcines was studied in a ceramic-lined melter with a glass surface area of 0.76 m². The melter contained 0.25 m³ of glass heated by the flow of an AC current (ranging from 600-1200 A) between two Inconel-690 slab-type electrodes immersed directly in the glass at either end of the melter tank. The melter was maintained at operating temperatures for 13.5 months and produced 62000 kg of glass. The maximum sustained operating period was 122 h, during which glass was produced at the rate of 70 kg/h. The basis design features of the melter, and some of the operating experiences, are discussed. The proposed use of ceramic-lined electric-heated glass melters for the vitrification of nuclear wastes is feasible, but additional studies of the chemistry of the melting process and of the corrosion process of the complex nuclear waste glasses are indicated.