Phase separation of molybdenum, cesium and selenium from the borosilicate glass containing simulated nuclear wastes under a CO2-rich heating atmosphere

Abstract Molybdenum, cesium and selenium along with potassium-rich materials were phase-separated onto the surface from the borosilicate glass containing simulated high level radioactive wastes by heat treatment under a CO 2 -containing atmosphere. The phase separation behaviors of potassium, molybdenum, cesium and selenium were characterized by FE-SEM, EDS, XPS and Raman analysis. These elements could be further extracted by leaching for recovery. The leaching results show that the extraction efficiencies of these elements under CO 2 -containing atmosphere were much higher than that under air atmosphere. Attempts were further made to investigate the effects of the melting temperature, melting time, the concentration of CO 2 gas and the amount of potassium carbonate flux on the extraction efficiencies of molybdenum, cesium and selenium from the glass phase under the CO 2 -containing atmosphere. As a result, more than ca. 80% molybdenum, almost 100% selenium and ca. 50% cesium were extracted in the leachate from the highly simulated borosilicate glass under the CO 2 -containing heat treatment. It is expected that this technique can be extended to study the separation of other fission products by optimizing the process parameters in the future research.