The application of synchrotron micro-computed tomography to characterize the three-dimensional microstructure in irradiated nuclear fuel

4D evolution of Cr23C6 precipitates in neutron-irradiated and annealed HT-UPS steel observed via synchrotron micro-computed tomography

“…Synchrotron µ-CT imaging was performed at the Advanced Photon Source (APS) beamline 1-ID-E at Argonne National Laboratory. A comprehensive description of the beamline for analogous µ-CT measurements is given in Thomas et al [18] and Hunter et al [47]. The beam was attenuated by the sample and then captured by a QImaging Retiga or Point Gray Grasshopper3 camera with an objective lens (× 10 or × 5) looking at a turning mirror to a 25 µm thick lutetium scintillator.…”

“…The beam was attenuated by the sample and then captured by a QImaging Retiga or Point Gray Grasshopper3 camera with an objective lens (× 10 or × 5) looking at a turning mirror to a 25 µm thick lutetium scintillator. Propagation-based phase-contrast-enhanced tomography [18] was utilized with a sample-to-detector distance ranging from 50 to 70 mm. The pixel pitch is calculated from the camera sensor pixel pitch and the objective lens and verified through known distance measurements.…”

“…As the surface is reconstructed utilizing triangles rather than rounded edges, it overestimates the surface area. It is typically assumed that a sphericity value of greater than 0.6 is perfectly spherical when using the marching cubes method [57,58]. The adaptation of the Crofton method [55] does this differently by instead using the Crofton formula to express perimeter and area utilizing intersections of discrete lines onto a unit sphere projection [55].…”

“…In the current research, synchrotron-based X-ray microcomputed tomography (μ-CT) was employed to understand four-dimensional (4D) Cr 23 C 6 precipitate evolution in HT-UPS steel before and after low fluence neutron irradiations up to 0.3 dpa (1.08 × 10 21 n/cm 2 ) at 600 °C by evaluating precipitate spatial distributions and geometries within identical specimens. A propagation-based phase-contrast-enhanced μ-CT technique was utilized, which enhances the edges of the absorption contrast image by allowing the interference of X-rays with differing phases caused by local changes in the refractive indices in a material [18,19]. The refractive index is proportional to the electron density and mass density of the features in a material, thus enabling the effective characterization of precipitates.…”

3d Autoencoders For Feature Extraction In X-Ray Tomography

“…Deeplearning approaches to instance segmentation are also possible [6,7] and they avoid the connected component filter to reduce computation time but that is a minimal advantage when weighed against the cost of added complexity to the training process. In in-situ studies, the porosity metrics may be calculated over multiple spatial locations within each scan volume [8,9] or across a time-sequence of scans [10,11] to identify both where and when porosity changes within the sample. Developments in instrument automation and streaming tomographic reconstruction [12] are now enabling the acquisition of full-field 3D images within seconds at synchrotron facilities, with data-generation rates of 1-10 giga-voxels per scan.…”