Liquid feed vitrification of high-level nuclear waste: Description and modeling of chemical reactions

• DOI: 10.1016/j.jnucmat.2025.155688
• Publication Date: 2025-02-10T16:09:35Z
• Authors: E. Sauvage; S. Schuller; Z. Nabyl; R. Podor; J. Lautru; P. Benigni; J. Klouzek; S. Mure; V. Benavent

In order to take into account the thermal effects associated with the decomposition of precursors(glass frit and waste, without prior calcination) in the multiphysics CFD (Computational FluidDynamics) simulations developed for cold crucible vitrification, mathematical modeling of denitrationkinetics is proposed. On the basis of a run-rerun method applied to DTA-TGA analysis carried outat different temperature ramps (10 to 40°C/minute), the degrees of conversion of the reactions havebeen determined and the kinetic parameters described by taking into account a weighted sum of 7elementary reactions of order n, whose rate constant follows an Arrhenius law. This global approachmakes it possible to describe the overall kinetics of each endothermic event satisfactorily, withouthaving to consider the complexity of the decomposition reactions of the initial pure compounds.However, analysis of the gases emitted during the reactions using thermogravimetric analysiscoupled with mass spectrometry (TGA-MS) and characterization by environmental scanning electronmicroscopy (ESEM) correlated with literature data enabled to describe the main chemical reactionsassociated with thermal events. This global approach can be transposed to other systems if thereactions are thermally activated.