Full-Scale In-Can Melting for Vitrification of Nuclear Wastes

A full-scale nonradioactive in-can melter became operational at Pacific Northwest Laboratory in April of 1977. The furnace has six independently controlled hot zones capable of providing 30 kW each at 1200°C and is able to accommodate cans up to 710 mm (28 in.) in diameter and 2.3 m (7ft) tall. New design concepts such as placing the entire can inside the furnace, supporting the can from the bottom, and charging the in-can melter through a water-cooled spout were demonstrated with this equipment. These new concepts have resulted in the elimination both of accumulations of the materials to be melted (batch) on top of the heat-transfer plates in the cans and of unvitrified waste in the top of the can. Melting rates of 100 kg/h (220 lb/h) were attained in 610-mm-diam (24-in.-diam) cans using test batches composed of calcined simulated waste from a nitric acid solution combined with borosilicate glass-forming frit. A 10-day continuous run was made in conjunction with a heated-wall spray calciner to demonstrate the reliability and operability of the equipment. Control of the in-can melting process using only remote monitoring equipment not attached to the can was also demonstrated.