Attachment F:
Joule Heated Melters
The DOE-EM program for immobilizing high-level waste currently utilizes Joule-heated melters (JHMs) to produce high-level waste waste glass. In Joule heating an electric current is passed through a material, in this case glass. The internal resistance of the material causes the electric currents to be dissipated as heat. A JHM is usually lined with refractory, and the glass is Joule heated by electricity transferred through the melt between nickel-chromium alloy electrodes, usually Inconel. The nominal melt temperature in JHMs is 1150ºC, which is only 200ºC lower than the melting point of the Inconel electrodes. These melters can be calcine fed or slurry fed and vitrification is a continuous or semi-continuous process.
JHM’s have been used for waste glass production in the United States, France, and Japan because of the high production rate and high glass quality. The size of these systems is limited only by the replacement crane capacity since all the structural support is provided by a stainless steel shell which contains the refractory. The Defense Waste Process Facility at Savannah River Site is the largest production melter of this type ever built. A larger one is under construction for use at the Waste Treatment Plant at the Hanford Site and replacement of this system (due to its size) is by rail instead of by crane.