Characterization of nuclear materials in solid particles or particles in liquid slurry, particularly in high level waste, can establish the elemental, organic, and isotopic compositions that effect the properties of the materials during nuclear fuel cycle activities and processes. Techniques to evaluate such detailed information, even at small concentrations, can support nuclear materials and science programs by increasing our ability to manage and control nuclear materials. However, radioactive materials analysis in liquids and slurries can be challenging using bulk approaches. We have developed a vacuum compatible microfluidic interface, system for analysis at the liquid vacuum interface (SALVI), to enable surface analysis of liquids and liquid-solid interactions using scanning electron microscopy (SEM). In this work, we illustrate the initial results from the in operando analysis of liquid samples of importance in the geologic disposal of uranium dioxide (UO2) spent nuclear fuel in a repository environment using in situ liquid SEM. A SALVI electrochemical cell, or E-cell, containing UO2 as the working electrode (WE) and platinum as reference and counter electrodes is prepared to study the corrosion potential in depository relevant conditions. The UO2 WE is prepared by SEM-FIB liftout. To make the WE in small dimension in micrometers within the E-cell, wet etching is used to prepare the gold substrate and conductive layer. A multiport feed-through is used to permit connections between the E-cell inside the SEM main chamber and the external electrochemical work station. Our results demonstrate that multimodal analysis of UO2 materials is possible using the SALVI Ecell and in situ SEM imaging. In operando and in situ liquid SEM enabled by SALVI can be used as a new approach to analyze radioactive materials in liquid and slurry forms of high level nuclear wastes. 

Analysis of radioactive materials using <i>in operando</i> and <i>in situ</i> liquid SEM

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

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Analysis of radioactive materials using in operando and in situ liquid SEM