PNNL

The International Atomic Energy Agency obtains uranium samples from nuclear power plants across the globe. Each sample contains key information about the types of nuclear activity occurring at the collection site. Trace materials within the samples can indicate activities like peaceful power generation or even potential nuclear proliferation.  

The samples can be challenging to obtain and are often very small. This makes each sample valuable in terms of maximizing the information gleaned from the contents. With limited quantities, there is interest in retaining as much of the samples as possible. The most used testing process involves sample destruction composition analyses.

The Science

To sidestep sample destruction during environmental and nuclear processing plant sample analysis, researchers at the Pacific Northwest National Laboratory (PNNL) applied a technique that is nearly non-destructive, faster, and requires a smaller sample size. The patented approach, known as in situ liquid secondary ion mass spectrometry, or liquid SIMS, allows samples to be retained for additional analyses in the future.

The Impact

This research fills a technical need to facilitate a fast analysis of complex liquid uranium samples or environmental slurries collected from the nuclear processing facilities. With this technique, minimal amounts of a sample, as small as a drop, are used for analysis.

Summary

Researchers demonstrated the use of a unique microfluidic vacuum compatible sample holder named SALVI (System for Analysis at the Liquid Vacuum Interface) to conduct in situ liquid time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) analysis of UO₂‐containing solutions. Dr. Xiao-Ying Yu and Dr. Edgar Buck led this research. Their initial result provides a promising approach in determining the signature chemical species in nuclear materials and environmental samples without the need of elaborate sample preparation steps (e.g., lengthy chemical separation before alpha spectrometry analysis). For instance, desiccating the liquid sample would cause the loss of valuable organic information that could be utilized to identify the source of the nuclear materials. The time‐consuming and labor‐intensive sample preparation in other techniques makes it difficult to analyze the large volume of samples quickly. Moreover, microfluidic analysis needs a very small quantity of liquid, that is a tiny droplet, significantly reducing the sample volume yet retaining measurement precision. The team demonstrated that the in situ liquid SIMS enabled by microfluidic reactors can facilitate fast analysis of complex liquid uranium samples, offering a new approach for environmental slurries collected from the nuclear processing facilities with much reduced sample volume and the potential for multimodal analysis.

Funding

Support for this work was provided by the Tactical Opportunity Pool from the National Security Directorate of PNNL. Additional programmatic support was provided by the Department of Energy Office of Nuclear Energy’s Spent Fuel Waste Science Technology program. The research was performed partially in the W. R. Wiley Environmental Molecular Sciences Laboratory, a national scientific user facility at PNNL. PNNL is operated by Battelle under the contract DE‐AC05‐76RL01830.