Numerical analysis of platinum group particle behavior in vitrification melter

Abstract

In the vitrification of high-level radioactive liquid wastes, platinum group particles originally included in the liquid wastes are mixed into molted glass and convected with the glass flow in vitrification melters. Though behaviors of the platinum group particles in the melters should be investigated to establish efficient melter operation methods, difficulties in observations or measurements of the particles in the actual melters due to high radioactivity have prevented enough investigation. In this paper, we present a numerical analysis method to evaluate the behaviors of the particles in the melters. Since the thermal convection field of the molten glass, electrical potential and particle distribution are formed by the interaction of the particles in the melters, we coupled these physical behaviors in the numerical method to evaluate the melter status with high accuracy. A numerical simulation was conducted and transient behaviors of the particles in the melters were determined. The results of simulation for ten batches of operation (each batch consists of melting, bottom heating and discharging operations) showed that an effective particle discharge can be achieved, as observed in mock-up experiments. These results imply that our numerical method can evaluate transient behaviors of the platinum group particles in vitrification melters. © Atomic Energy Society of Japan.