PNNL

Abstract

This paper reports the phase behavior of a multicomponent borosilicate glass melt with 0?3 mass% Cr2O3 at 800?1500°C in equilibrium with air. Both upper and lower liquidus temperatures were observed. When the temperature was between the upper and lower liquidus temperatures, eskolaite (Cr2O3) formed in melts with >2 mass% Cr2O3. Below the lower liquidus temperature, a dispersed chromate phase appeared in the melt that eventually became macroscopically segregated. The chemical durability of the glasses was virtually unaffected by chromium concentration. The particular glass studied was prototypic for the vitrification of high-Cr high-level radioactive wastes stored in underground tanks at the Hanford site. The results suggest a significant potential cost benefit for Hanford tank waste cleanup.