Researchers at the U.S. Department of Energy’s Argonne National Laboratory have created a new way to measure how nuclear fuel moves heat. The microscale technique helps predict fuel behavior under extreme conditions and could lead to safer reactor designs.
Understanding thermal conductivity is critical for nuclear reactor safety. Thermal conductivity measures how well a material transfers heat. In nuclear fuel, radiation damage reduces this property over time, making accurate predictions essential.
Yinbin Miao, a principal materials scientist at Argonne , explained the importance. “Thermal conductivity dictates how effectively heat is transferred within nuclear fuel. It helps us make sure the fuel doesn’t get too hot and stays safe to use.”
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The new method, called the suspended bridge technique, uses two tiny microfabricated platforms connected by an ultrathin sample. The samples are hundreds of times thinner than a human hair. Measurements take place in a vacuum.
This small scale allows researchers to measure individual components within complex fuel systems without interference from surrounding materials. The results are highly accurate.
The team tested their method on materials with well-known thermal conductivity, including stainless steel and uranium-molybdenum alloys. They used a focused ion beam to prepare samples and tested rods of different lengths. The results matched existing data, confirNming the method’s reliability. Computer simulations showed that the tiny sample size does not affect the results for most nuclear materials.
The technique offers several advantages. It can measure radioactive materials, including those already used in reactors. It works on samples as small as a few micrometers, making handling easier. Currently, it measures at temperatures from 5 to 400 kelvins (about -450°F to 260°F) . The team plans to expand this range up to 1,000 kelvins (about 1,340°F) , making it useful for advanced nuclear fuels.
Knowing how thermal conductivity changes during reactor operation helps scientists design safer fuels and predict when fuel needs replacement. Beyond nuclear energy, the method can also measure electrical properties, which could aid research in thermoelectric materials.
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Abdellatif Yacout, a senior researcher at Argonne , called it a big step forward. “It not only enhances reactor safety but also supports the design of next-generation nuclear systems.”
The research was supported by DOE’s National Nuclear Security Administration. The suspended bridge method was initially developed in collaboration with the University of Illinois at Urbana-Champaign.
