[SY-B9] Advances in X-ray Diffraction Line Profile Analysis of Dislocation Loops in Zr - Insights from Atomistic Modelling.
Irradiation-induced growth (IIG) of Zr-alloy nuclear fuel cladding can limit the service life of nuclear fuel. It involves a macroscopic shape change driven by the formation and growth of populations of dislocation loops.
Efforts to create Zr-alloys that are resistant to IIG thus rely on accurate determination of the size distribution and number density of dislocation loops in irradiated candidate alloys. X-ray diffraction (XRD) can, in principle, provide this information via an analysis of changes to the diffraction peak shapes. Such methods are well developed in the study of plastic deformation, but the different character of the defects formed under irradiation complicates the analysis. An improved understanding of the effect of dislocation loops on the diffraction peak shapes is therefore required.
We have constructed atomistic models of controlled defect populations in Zr and generated theoretical XRD profiles. We have compared these with experimental profiles and analysed changes in lineshape in terms of contributions from the strain fields of individual defects. In particular, we are able to explain the appearance of features in the experimental profiles that are peculiar to irradiated material. We show that these new features contain information about the character of the dislocation loops in irradiated material.
Efforts to create Zr-alloys that are resistant to IIG thus rely on accurate determination of the size distribution and number density of dislocation loops in irradiated candidate alloys. X-ray diffraction (XRD) can, in principle, provide this information via an analysis of changes to the diffraction peak shapes. Such methods are well developed in the study of plastic deformation, but the different character of the defects formed under irradiation complicates the analysis. An improved understanding of the effect of dislocation loops on the diffraction peak shapes is therefore required.
We have constructed atomistic models of controlled defect populations in Zr and generated theoretical XRD profiles. We have compared these with experimental profiles and analysed changes in lineshape in terms of contributions from the strain fields of individual defects. In particular, we are able to explain the appearance of features in the experimental profiles that are peculiar to irradiated material. We show that these new features contain information about the character of the dislocation loops in irradiated material.