Application of X‐ray microcomputed tomography in the characterization of irradiated nuclear fuel and material specimens

Abstract

X-ray microcomputed tomography (μCT) was applied in characterizing the internal structures of a number of irradiated materials, including carbon-carbon fibre composites, nuclear-grade graphite and tristructural isotropic-coated fuel particles. Local cracks in carbon-carbon fibre composites associated with their synthesis process were observed with μCT without any destructive sample preparation. Pore analysis of graphite samples was performed quantitatively, and qualitative analysis of pore distribution was accomplished. It was also shown that high-resolution μCT can be used to probe internal layer defects of tristructural isotropic-coated fuel particles to elucidate the resulting high release of radioisotopes. Layer defects of sizes ranging from 1 to 5 μm and up could be isolated by tomography. As an added advantage, μCT could also be used to identify regions with high densities of radioisotopes to determine the proper plane and orientation of particle mounting for further analytical characterization, such as materialographic sectioning followed by optical and electron microscopy. In fully ceramic matrix fuel forms, despite the highly absorbing matrix, characterization of tristructural isotropic-coated particles embedded in a silicon carbide matrix was accomplished using μCT and related advanced image analysis techniques.

Unconventional Pathways to Carbide Phase Synthesis via Thermal Decomposition of UI4(1,4-dioxane)2

“…Since the penetration of X-rays (i.e., at the Cu Kα wavelength) through U-based solid compounds (e.g., UO 2 ) is only about 10 μm or less, 51 the sample was scraped to obtain bulk microparticles oriented along all directions uniformly and then analyzed by XRD to enable a better understanding of the sample as a whole. The data obtained from scraped samples showed less UO 2 content than the data taken on the sample surface.…”

3D Visualized Characterization of Fracture Behavior of Structural Metals Using Synchrotron Radiation Computed Microtomography

“…High photon flux and high-speed camera utilized at third-generation synchrotron X-ray sources mean that SR-µCT should be a powerful tool and provides a promising way to clarify the fracture behavior of the composites. The past decade has seen the progress in our understanding of MMC damage process [28][29][30]. Advances achieved in SR-µCT characterization technologies of materials, such as X-ray energy, and high spatial and temporal resolutions, largely benefit the MMC research.…”

Seeing through nuclear fuel: Three-dimensional, nondestructive X-ray microscopy and volumetric analyses of neutron-irradiated TRISO-coated fuel kernels

“…Several studies have employed micro-XCT to image unirradiated or neutron-irradiated TRISO particles bearing surrogate (e.g., Al 2 O 3 ) or fuel (i.e., uranium)-based kernels. Due to the high mass attenuation coefficient of uranium (relative to the typical X-ray energies available with common X-ray tube sources or synchrotron sources), these studies have been limited to characterization of surrogate kernels and surrounding coating layers or, in the case of fuel-bearing particles, only the coating layers [8][9][10][11][12][13][14][15].…”