Probing Uranium's Mysteries

Posted: July 22, 2013 - 3:28pm | Y-12 Report | Volume 10, Issue 1 | 2013

Using a custom nuclear magnetic resonance probe, chemist Ashley Stowe explores previously unseen properties of uranium. He also aims to prevent illegal trafficking of that commodity through his semiconductor crystals research.

If you ask Ashley Stowe what he does for a living, he’ll tell you he makes toasters. Don’t believe him. What this Y‑12 chemist actually does is a bit more complicated. He’s not making kitchen appliances better; he’s making America safer.

“Y‑12 projects typically have homeland security relevance,” said Stowe, who jokingly uses the toaster line to avoid divulging sensitive information. “I have a sense of purpose that the research I do and the resulting solutions have a real impact on the safety of others.”

Two of his latest projects certainly fall into that category. He’s exploring previously unseen properties of uranium and developing new methods to detect nuclear materials.

No matter the project, though, Stowe relishes the opportunity to solve mysteries every day. “I have always been interested in how or why things happen,” he said. “I come to work, ask research questions and then work with a great group of people to answer them.” The answers to his latest questions might have broad implications for Y‑12’s nuclear nonproliferation, forensics and detection work.

MRI for Scientists

Most pharmaceutical labs and colleges in the country have a nuclear magnetic resonance, or NMR, instrument that allows their scientists to see certain chemical properties at the quantum level. What they don’t have is a good reason to use those instruments to explore uranium atoms.

Ashley Stowe does. He hopes to look at uranium process chemistry with the aid of NMR technology, which he describes as “MRI for scientists” because it operates on the same principles as the magnetic resonance imaging scanners that allow doctors to see cells in the human body. But first, he needed a special instrument.

“Uranium is unique in that its nuclear resonance occurs at very low frequencies, outside the range of a standard NMR probe,” Stowe said. He worked with an NMR manufacturer to make a custom probe designed specifically to look at uranium-235. “They said it’s the first one they’ve ever made.”

Other researchers have used NMR spectroscopy to understand uranium chemistry. But they do so secondhand, by evaluating the elements attached to a uranium atom in a compound and only inferring the properties of uranium from that — like trying to determine what’s happening in one house just from looking in all the other houses in the neighborhood. Stowe’s new tool gives him the ability to see things that no one has ever seen.

“The information I’m collecting with this new uranium probe is unique because we can look directly at the uranium atom within compounds,” Stowe said. “This allows us to remove some of the guesswork and better understand uranium chemistry — in ways that researchers never have before.”

Stowe is conducting baseline testing and building a database of uranium compounds. “I’m taking familiar materials and looking at them through a new lens,” he explained. “A historical catalog of compounds made by different chemical processes will give us unique NMR signatures.”

He is careful to stress the technology’s infancy but thinks a signatures database will ultimately help improve Y‑12’s nuclear forensics and nonproliferation efforts. “The goal is to understand the subtleties in uranium chemistry well enough that when we get an unknown sample, we’ll be able to analyze it and compare it against historical standards to learn more about it,” Stowe said.

While this technology bolsters Y‑12’s efforts to study uranium once it’s found, another of Stowe’s projects will help find uranium in the first place (Learn more).