Effect of sucrose on technetium and rhenium retention during vitrification of low‐activity wastes. Issue 12 (17th August 2022)

• Record Type: Journal Article
• Authors: Lee, SeungMin; Jin, Tongan; Rivers, Eden; Kloužek, Jaroslav; Luksic, Steven; Marcial, Jose; George, Jaime; Dixon, Derek R.; Eaton, William C.; Kruger, Albert A.
• Is Part Of: Journal of the American Ceramic Society. Volume 105:Issue 12(2022)
• Page Start: 7321
• Page End: 7333
• Publication Date: 2022-08-17
• Subjects: low‐activity waste -- retention -- rhenium -- sucrose -- sulfur -- technetium; Ceramics -- Periodicals; 620.1405
• DOI: 10.1111/jace.18701
• Languages: English
• ISSNs: 0002-7820

Abstract

Abstract: Sucrose (C12 H22 O11 ) has been used in low‐activity waste (LAW) melter feeds containing large fractions of nitrates, nitrites, or both because it facilitates foam suppression and denitration. This study focused on the effect of sucrose in LAW feeds on technetium (Tc) and rhenium (Re) retention. The amount of sucrose added in feeds was varied to differentiate the carbon‐to‐nitrogen mole ratio (C/N ratio). The results show that larger sucrose addition (higher C/N ratio) enhances Tc and Re retention. Reducing conditions induced by sucrose decomposition and early chemical reactions between sucrose and NaNO3 /NaNO2 are expected to increase Tc and Re retention. However, high sucrose addition decreased sulfur (S) retention slightly because sodium sulfate decomposes in reducing conditions at lower temperature. This early sulfate decomposition can affect Tc and Re retention partly because these species can be soluble in sulfate phases. This correlation indicates that the decrease of sulfate phases in the glass by early decomposition can reduce the solubility of Tc and Re in the sulfate phases, which may increase Tc and Re retention in the glass. In addition, continuous gas evolution and vigorous foaming at the foaming temperature range of 700–900°C may influence Tc and Re retention process interrupting retention or facilitating volatilization.