621.039.736 During the operation of a nuclear power plant, large volumes of medium-level radioactive liquid wastes are formed. These radionuclides must be incorporated into an insoluble matrix prior to final burial. The wastes consist of solutions containing sodium salts (predominantly nitrates and borates), different impurities, and organic compounds. At the present time, liquid wastes from nuclear power plants are bitumenized and cemented.An effective method of solidification is fixing wastes into a glass-like matrix which is highly stable chemically and mechanically strong. Solidification in borosilicate glass gives 0.2-0.3 m 3 of solid material per 1 m 3 of liquid; this is 3.6 times smaller than in the case of solidification of a corresponding volume in bitumen and 10 times smaller than solidification in concrete. The leach rate of radionuclides decreases by 100 and 10,000 times, respectively. Moreover, compared with bitumenization, this method does not present a fire hazard during reprocessing, transport, and storage of the wastes.Successful long-term operation of the vitrification apparatus in the Industrial Association "Mayak" in the case of reprocessing of high-level wastes made it possible to recommend vitrification and the basic technical solutions for the construction of the equipment and for medium-level wastes from nuclear power plants.The vitrification apparatus developed at the Joint-Stock Company "Sverdlovsk Scientific-Research Institute of Chemical Machinery" for a nuclear power plant (Fig. I) includes a flow-through pipe-inside-pipe type evaporator, flux dispensing units, gas purification unit, a packaging unit, and an electric furnace. The setup is equipped with water and electricity supply systems and a system for automating and monitoring the technological process. The flux dispensing unit consists of a bunker for storing and dispensing the glass-forming components. The gas-purification unit contains a bubble-tank condenser, a condensate collector, an absorption column, and rough and t-me purification filters. The packaging unit includes a circular conveyor with an electric drive extended outside the radiation shielding, containers for filling with the glass mass, devices for monitoring the glass mass flowing into the container from the furnace, and an off-loading system for transporting the glass-filled containers to the storage location.The electric furnace (Fig. 2) consists of a ceramic bath placed inside a water-cooled metal case. To prevent the calcinated material, which has not been completely melted, from entering the pouring apparatus, the bath is separated by a water-cooled barrier with a submerged channel into two zones --founding and pouring. Founding is performed by means of heat released during the passage of electric current through the melted glass mass. Electricity is supplied to the melt from vertically positioned bottom metal electrodes, secured into thewater-cooled current leads.The electrical furnace operates in a continuous mode: Electricity continues to flow to the e...