Characterization and modeling of chemical reactions taking place during the vitrification of high level waste in cold crucible

International audienceSeveral chemical reactions take place during the vitrification of high-level nuclear waste. The integration of these chemical aspects in CFD codes is today one of the key points in the process of improving the prediction capabilities of numerical tools. In this study, based on simultaneous differential thermal analysis-thermogravimetry (DTA–TGA) and run/rerun method, we propose a modeling of the kinetics of chemical reactions taking place when the nuclear glass precursors are subject to constant heating rates. For the mathematical modeling, a weighted sum of n-order reactions is used to describe the overall mechanism. A hybrid approach coupling Kissinger and least squares method is performed to identify the apparent kinetic parameters. Along with the thermal characterization, we also propose a qualitative analysis of the reactions phenomenology through microstructural evolution and evolved gaz analysis based respectively on scanning electron microscope (SEM) and thermogravimetry–mass spectrometry (TGA–MS)