Strain measurement in thin layer helium implanted polycristal using X-Ray micro diffraction
Abstract
The swelling of nuclear fuel (uranium dioxide, UO2) in storage conditions is partly due to the alpha decay (helium production) of radioactive fission products. In order to study the behaviour of spent fuel, helium ions are implanted at the surface of fresh UO2 polycrystalline disks. This technique allows the study of nuclear fuel in storage conditions while dealing with low radioactive samples. X-ray micro diffraction is used to measure the strain in the implanted layer at microscopic scale. A previous work [1,2] showed that the layer displacement depends on the depth z, perpendicular to the sample surface, and three components of the deformation gradient, ξzz, ξyz and ξxz are non-zero. Their values depend on the grain orientation. In this abstract, the sample preparation and image acquisition are first described. Then, an improved procedure for automatic Laue diffraction patterns analysis is presented. Finally a mapping of intragranular strain is shown on few adjacent grains.