An inverse method for the thermal fluxes during nuclear glass package cooling long-term analysis
Abstract
In the current work, we analyze the thermal behavior and thermo-mechanical response of a high-level nuclear waste (HLW) package. Based on a thermal vitrification experiment with inactive borosilicate glass, we report a method to model, simulate and predict the HLW thermal behavior over time-scales corresponding to the useful lifespan of a HLW, e.g. potentially in hundreds of thousands of years. The proposed thermal approach relies on an inverse method using homogenized fluxes at the surfaces of the HLW package during the whole vitrification process. The resulting thermal modeling and simulation is then used as input in a viscoelastic structural analysis of the thermal stress build-up inside the glass block. This inverse method then allows us to compare the residual stresses of two kinds of HLW package vitrification processes the experimental one with inactive glass; and a prediction of the cooling and solidification for a HLW with nuclear glass over the long term time-scale.