Vitrification of Simulated Medium- and High-Level Canadian Nuclear Waste in a Continuous Transferred Arc Plasma Melter

A continuous, laboratory-scale, 40-kw, transferred arc plasma melter was designed and built for the vitrification of nuclear waste. Borosilicate glass, high silica glass and sphene glass-ceramic were successfully melted with the waste using argon and argon-oxygen transferred arcs. The use of both direct heating and indirect heating was examined. The loss of total glass weight and the elemental losses ofNa, Cs, U and Nd were examined as a function of operating conditions. The losses ofCs during melting were from 25 wt% to 73 wt% and depended on operating conditions. The loss of Cs during melting could be minimized by decreasing the plasma power, increasing the feed rate, using indirect heating rather than direct heating and choosing suitable waste compositions. The injection of oxygen and the addition of zeolite to the glass formers did not significantly reduce Cs losses.