| Abstract Scope |
Tristructural isotropic (TRISO) fuel is a leading candidate for next-generation high-temperature nuclear reactors due to its multilayered structure that enhances fission product retention. A key component is the carbon buffer layer, designed to be ~50% porous to accommodate fuel kernel swelling under irradiation and trap gaseous fission products. Accurate, per-particle measurement of buffer density is critical to ensuring fuel performance, yet conventional methods like mercury porosimetry are limited to bulk measurements and generate hazardous waste. Radiography has emerged as a promising alternative, but previous implementations have suffered from inaccuracies due to epoxy infiltration into buffer layer leading to significant overestimation of buffer layer density compared to the nominal value. This work presents an improved radiography method for measuring TRISO buffer density on a per-particle basis using x-ray attenuation principles. Additional calibrations were implemented, a new mounting procedure for spherical TRISO cross sections was established, and a modified approach to buffer layer segmentation was explored. These improvements reduced the variation in measured buffer densities and generated a large statistical sampling of TRISO, although infiltration of higher-density material (e.g., pyrolytic carbon fragments) into the buffer pore structure remains a challenge. The modified methodology demonstrates the potential for extracting quantitative information from the buffer layer, establishing a foundation for high-throughput evaluation of TRISO fuel. These findings not only improve buffer density characterization but also highlight opportunities for future work in refining layer-specific radiography analysis, supporting the development of safer and more reliable nuclear fuels.
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