Dose needed to observe a 50 μm radius void at one sigma in a 10 g/cm2 urania sample (dotted) and a 4 g/cm2 urania sample (dashed) as a function of x-ray energy (left axis). (Solid line) X-ray mean free path, λ, in uranium oxide (right axis).
Schematic of an x-ray geometry. The x-ray position resolution is determined by simple geometry to be a function of the source spot size and the detector resolution. A collimator can shield the detector from radiation from the object but also reduces the field of view to narrow slices of the object. Tomographic images may be taken by shifting the object and performing rotations for each slice. Δx S is the x-ray source size and Δx D is the detector resolution.
Proton flux required to observe a 50 μm radius void in a 1 cm thick thoria or urania fuel rod (dashed line) and resolution (solid line) as a function of collimator angle.
Schematic layout of a proton radiography system.
Proton radiography system. Picture at top shows the proton radiography system. (Bottom left) The graded degraded, goniometer, and the lead rod object. (Bottom right) A schematic representation of how an object could be mounted in a cast to provide radiation shielding.
Areal density (left) proton radiography and (right) X-ray radiography. The rotation between the feature in the second pellet from the top is an assembly difference between the two experiments.
Comparable slices measured with proton (left), x-ray (center), and background corrected x-ray tomography. We note that no background correction is needed for the proton data.
Densities for lineouts along a horizontal line in the center of the center pellet in Figure 7 (solid line) and through the diagonal defect in the fourth pellet from the bottom (dashed line). (Left) Proton tomography, (center) X-ray tomography with no background correction, (right) x-ray tomography with background correction.
x-y cross section through the center of the reconstructed densities for pRad (left) and xrad (right) for one of the unania pellets. The bottom panels show density, the top panels show the edge function. This section is taken through the crack visible in the lower part of the third pellet from the bottom in Figure 7 .
Slice through a tomographic reconstruction of part of the throria test assembly. The two vertical strips extending through the object are reconstruction artifacts.
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