Microscale Electrochemical Corrosion of Uranium Oxide Particles

Area of Science:

• Nuclear Chemistry
• Materials Science
• Electrochemistry

Background:

• Spent nuclear fuel corrosion is critical for safe long-term storage.
• Radiation contamination poses significant challenges for experimental analysis of nuclear materials.
• Existing methods for studying spent fuel corrosion are limited by contamination risks and scale.

Purpose of the Study:

• To develop a miniaturized electrochemical system for studying uranium oxide (UO2) corrosion.
• To reduce radiation contamination risks associated with spent nuclear fuel analysis.
• To investigate the electrochemical oxidation of UO2 under conditions relevant to nuclear fuel storage.

Main Methods:

• Adapted the System for Analysis at the Liquid-Vacuum Interface (SALVI) to create a miniaturized working electrode (WE).
• Utilized a Nafion layer to protect UO2 particles within the miniature electrochemical cell.
• Employed Atomic Force Microscopy (AFM) to characterize the UO2 electrode surface.
• Used X-ray Photoelectron Spectroscopy (XPS) to analyze the oxidation states of uranium.

Main Results:

• AFM confirmed a dense UO2 layer participating in electrochemical reactions with minimal particle redistribution.
• XPS revealed distinct distributions of U(IV), U(V), and U(VI) on pristine and corroded UO2 electrodes.
• The presence of U(V)/U(VI) confirmed electrochemically driven UO2 oxidation.
• Observations of U(V) suggested interfacial water plays a key role, simulating water-lean storage conditions.

Conclusions:

• The developed microscale electrochemical platform offers a low-dose, reproducible method for spent fuel corrosion studies.
• The system provides design flexibility and separates the alpha-effect, crucial for accurate analysis.
• This approach enables detailed investigation of UO2 corrosion with minimal radiological material, paving the way for diverse configurations.