Briana Hiscox wanted to grow up to be just like her mother—and father. Raised by two engineers, Hiscox envisioned a similar career from a young age. She found the chemical and civil engineer paths of her parents enticing, but what fascinated her most was fission, the process of splitting an atom into two parts. When she stepped foot into college, she resolved she wouldn’t step back out until she received her Ph.D. in nuclear engineering.
“I decided that I wanted to be a nuclear engineer because I was captivated by it and I thought that nuclear power could help save the world by providing low carbon energy,” said Hiscox. “After spending the year actually involved in the nuclear industry, taking classes and doing research, I still wholeheartedly believe that nuclear energy can help our environment.”
This past summer, halfway to the finish line, Hiscox interned at one of the nation’s most renowned laboratories for nuclear technologies: Oak Ridge National Laboratory (ORNL). As a participant in the Nuclear Engineering Science Laboratory Synthesis (NESLS) program, Hiscox gained exclusive insight into the daily tasks of a federal nuclear engineer as well as the vast amounts of exemplary research conducted in the lab’s historic halls. Her own contributions as an intern in the Reactor Nuclear Systems Division helped lay the groundwork for a cleaner and safer nuclear future, one that could see several new reactors online by the time Hiscox obtains her doctorate in 2020.
“Nuclear engineering is widely affected by public opinion and politics,” said Hiscox, who received her bachelor’s in mechanical engineering from the University of Connecticut and is pursuing her master’s and doctorate in nuclear science and engineering at Massachusetts Institute of Technology (MIT). “For commercial nuclear engineering to remain in use, the public must be convinced that it is safe. While nuclear engineering is already very safe, I think it might soothe the public if researchers show we are working to make it even safer.”
The NESLS program is administered by the Oak Ridge Institute for Science and Education (ORISE) for the U.S. Department of Energy (DOE). It pairs students in nuclear engineering or related fields with national laboratory staff scientists on projects related to nuclear security technologies and other nuclear science disciplines. Hiscox applied to the program to explore accident-tolerant nuclear fuels, a research area she studies at MIT.
Nuclear fuel and cladding materials with potentially enhanced accident tolerance are being explored by the DOE Office of Nuclear Energy Advanced Fuels Campaign and the nuclear industry to reduce the potential impact of severe accidents like those that occurred at Fukushima Daiichi in 2011.
A wide variety of nuclear fuels including liquid, metal and oxide fuels are used in reactors, with uranium oxide the most common fuel, but Hiscox’ research focused on a type of ceramic fuel called fully ceramic microencapsulated fuel (FCM). Hiscox explained that the tri-isotopic (TRISO) particles in this fuel are spherical in shape and act as miniature pressure vessels, helping to contain fission products rather than allowing them to overheat. The silicon carbide matrix surrounding the TRISO particles is also a defense mechanism that enables very high fission product retention.
Scientists have been conducting research on TRISO fuels for years, but they are constantly investigating ways to make the fuels more efficient. Typical high temperature gas reactor fuels contain TRISO particles suspended in a graphite matrix, as graphite is known for its ability to withstand extremely high temperatures. Hiscox’s research on FCM fuel in high temperature gas reactors is focused on suspending the TRISO particles in a silicon carbide matrix instead.
“By the end of the internship, our results suggested that while adding silicon carbide decreased the reactivity by increasing the enrichment of the fuel to less than 20 percent, we were able to get comparable cycle lengths,” said Hiscox, who conducted research under her mentor Nicholas Brown, Ph.D., in the Advanced Reactor Systems and Safety group.
“My favorite part of the research was when I got the results back from a simulation and I thought, ‘Huh, I wonder what would happen if I changed this variable?’ And then I did, and I got to see the results of that. Sometimes the results didn’t turn out the way I anticipated they would. But, if I knew what was going to happen before it did all the time, it wouldn’t be good research. Learning new things is what makes it fun.”
Hiscox hopes to return to ORNL for full-time employment after she obtains her doctorate. She appreciates the lab’s robust and diverse scientific workforce and enjoys the lab’s location nestled in the hillsides of Oak Ridge, Tenn., but what compels her most to return is her childhood dream to change the world. At the lab, she feels she can.