Oak Ridge National Laboratory researchers used the nation’s fastest supercomputer to map the molecular vibrations of an important but little-studied uranium compound produced during the nuclear fuel cycle for results that could lead to a cleaner, safer world.

The study by researchers from ORNL, Savannah River National Laboratory and the Colorado School of Mines used simulations conducted on ORNL’s Summit supercomputer and state-of-the-art neutron spectroscopy experiments conducted at the Spallation Neutron Source to identify key spectral features of uranium tetrafluoride hydrate, or UFH, a little-studied byproduct of the nuclear fuel cycle. The findings may enable better detection of this environmental pollutant and better understanding of how environmental conditions influence the chemical behavior of fuel cycle materials.

“In this kind of work, we don’t have the luxury of choosing what kinds of materials we work with,” said Andrew Miskowiec, an ORNL physicist and lead author of the study. “We’re often dealing with small quantities or even just particles of byproducts and degraded material that no one intended to make of compounds that we don’t know much about. We need to know: If we found this material in the field, how would we recognize it?”

UFH forms when uranium tetrafluoride, a radioactive salt routinely used in producing uranium metal, begins to break down after immersion in water for 12 hours or longer. Even though scientists have studied uranium and its power to split the atom for nearly a century, most of those studies have focused on intentional results rather than unintended byproducts like UFH.

“From World War II through the Cold War, we have decades of study, but the main concern was making things work from a production standpoint, like building bombs and powering reactors,” Miskowiec said. “UFH wasn’t considered valuable for those purposes. That means it hasn’t been studied as closely and isn’t as well understood. We need to know as much as we can about these materials in order to know what to look for when we discover them in the wild.”