During a presentation at the Winter Conference on Plasma Spectrochemistry, Hunter Andrews, an R&D associate at the Oak Ridge National Laboratory (ORNL) spoke about advanced nuclear fuel analysis. Andrews and his team at the ORNL have been experimenting with the use of laser induced breakdown spectroscopy (LIBS) for rapid elemental imaging of surrogate tri-structural isotropic (TRISO) particles for nuclear reactors.
LIBS is a form of atomic spectroscopy that determines the elemental composition of materials using a laser pulse to create a micro-plasma on the surface of a sample, allowing the analysis of its elemental composition based on the emitted light spectrum. This spectrum is collected using an emission spectrometer. The resulting spectral lines are analyzed to identify and quantify the elements present in the sample based on their unique emission wavelengths. LIBS is a commonly used technique for solid nuclear fuel analysis in the energy industry.
“We can use LIBS as a technique to save us analytical time to locate regions of interest,” Andrews said. “Then look using higher resolution sensitivity.”
TRISO particles are the “most robust nuclear fuel on Earth” made up of uranium, carbon, and oxygen, according to the United States Department of Energy (1). TRISO fuels are structurally more resilient to neutron irradiation, corrosion, oxidation, and high temperatures, compared to other reactor fuels, according to the Department of Energy. These particles are proposed nuclear fuel alternative in high temperature reactors and are typically enclosed in a graphite compact in the reactor core. However, due to their robustness, elemental analysis of TRISO particles proves difficult.
LIBS, however, can analyze the sample surface and detect elements including carbon and oxygen, which can make it a useful method for analyzing small, multilayered particles, the team wrote in an abstract for the study (2). In their research, LIBS was “successfully used for discerning small layers (30–50 μm), detecting the location of carbon and oxygen layers, providing fast 2-D mapping (<5 min per particle) and rapid depth profiling (10 s per particle) (2).
“The versatility of LIBS sensitivity and its speed allow for high throughput measurements,” Andrews said.