Prediction of the corrosion behavior of spent uranium oxide (UO2) fuel is needed for developing predictive performance assessment models for a geologic repository. Currently, the Fuel Matrix Dissolution Model (FMDM) is being used for modeling UO2 chemistry in the Engineered Barrier System (EBS) and includes the effects of oxidants, oxygen and hydrogen peroxide generated from radiolysis of the fuel in contact with water as well as the role of hydrogen on limiting corrosion.
The aim of this work is to investigate the corrosion of UO2 in situ in the Scanning Electron Microscope (SEM). The corrosion potential (Ecorr) is measured using an electrochemical workstation and a unique microfluidic reactor containing three-electrodes and compatible for multiple analytical platforms, termed System for Analysis at the Vacuum Liquid Interface (SALVI) electrochemical cell (E-cell) which has been developed at PNNL. This approach aims to provide real-time and in operando monitoring of UO2 electrode stability and morphological change and to study the UO2 corrosion process at the microscale. The results will be utilized to support the Mixed Potential Model (MPM) that has been developed for the repository program.