Rhenium volatilization in waste glasses

Abstract

h i g h l i g h t sRe did not volatilize from a HLW feed until 1000°C. Re began to volatilize from LAW feeds at $600°C. The vigorous foaming and generation of gases from salts enhanced Re evaporation in LAW feeds. The HLW glass with less foaming and salts is a promising medium for Tc immobilization. a b s t r a c tWe investigated volatilization of rhenium (Re), sulfur, cesium, and iodine during the course of conversion of high-level waste melter feed to glass and compared the results for Re volatilization with those in low-activity waste borosilicate glasses. Whereas Re did not volatilize from high-level waste feed heated at 5 K min À1 until 1000°C, it began to volatilize from low-activity waste borosilicate glass feeds at $600°C, a temperature $200°C below the onset temperature of evaporation from pure KReO 4 . Below 800°C, perrhenate evaporation in low-activity waste melter feeds was enhanced by vigorous foaming and generation of gases from molten salts as they reacted with the glass-forming constituents. At high temperatures, when the glass-forming phase was consolidated, perrhenates were transported to the top surface of glass melt in bubbles, typically together with sulfates and halides. Based on the results of this study (to be considered preliminary at this stage), the high-level waste glass with less foaming and salts appears a promising medium for technetium immobilization.Published by Elsevier B.V.

Melter Feed Reactions at T ≤ 700°C for Nuclear Waste Vitrification

“…The knowledge gained will enhance our understanding of the conversion of melter feed to molten glass, and also elucidate the behavior of volatile components, such as T c and I. 31 In this study, we focused on batch reactions that occurred before the gas evolution was complete 28,30 and the volume of glass feed significantly shrank, 24,25 in particular during heating at a constant rate to 700°C. Above this temperature, significant changes occur with the formation of a connected melt, foaming and the dissolution of quartz.…”

Effect of V2O5 on crystallization tendency and chemical durability of Mo-bearing aluminoborosilicate glass

“…On account of the solubility of Na 2 MoO 4 in water, the yellow phase can severely decrease the chemical durability of nuclear waste forms. In addition, the yellow phase would also corrode melter liners and impede the vitrification process [10][11][12].…”

The structure of rhenium‐containing sodium alumino (iron) phosphate glasses

“…Thus, Re behavior in phosphate glasses is, in principle, similar to that in borosilicate glasses and slightly different from Tc behavior, in particular, no Re(IV) is formed. Formation of Re(0) was observed in Ref …”