Removal of Ru from Simulated High-Level Waste Prior to the Final Vitrification into Borosilicate Glass Using Tin as the Alloying Element: Feasibility Study

Abstract

Ruthenium (Ru) was removed from molten borosilicate glass containing simulated radioactive waste by using tin as the solvent metal. The metal and glass phases were separated from each other and examined by X-ray diffraction (XRD), scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM-EDX). The composition of alloy and glass phases was analyzed by inductively coupled plasma optical emission spectroscopy (ICP-OES) and atomic absorption spectroscopy (AAS). The percent extraction fraction of Ru was found to be ~9%. Significant quantities of Fe, Te, Ni, and Mo were also found in the alloy phase. Formation of the Ru3Sn7 intermetallic compound was observed in the Sn-Ru alloy. The recovery of Ru was ~9%. Some amounts of Ni, Fe, Te, and Mo were found to migrate to the metal phase, leaving Cs, Sr, and Zr in the glass phase.