Investigation of Foaming in Liquid‐Fed Melting of Simulated Nuclear Waste Glass

Abstract

Melt foaming in alkali‐iron borosilicate glasses considered for nuclear waste disposal was investigated to identify the causative reactions and stabilizing mechanisms. Foaming is attributed to the release of oxygen and water vapor from the melt. The oxygen is suggested to originate from oxidation‐reduction reactions of species other than iron. Foaming problems are largely solved under reducing conditions, which result in less stable foams. The results suggest that a greater proportion of water vapor is released into the foam under more reducing conditions. The water destabilizes the foam by viscosity or surface tension effects and causes the bubbles to rupture on the melt surface.