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Nuclear Science User Facilities 116 high-quality orientation data.The effects of irradiation damage on the orientation data are not determined in this study and may be an area of consideration for future research work. Irradiation damage can introduce significant numbers of defects into the SiC lattice as well as generate residual stresses that may adversely affect the PED pattern and the resulting crystallo- graphic orientation determination e.g. lowering the Index parameter. Summary of Phase 2 resultsCrystal- lographic characterization of grain boundaries and triple junctions in the SiC layer by PED utilizingASTAR ASTAR data has been collected in every area previously analyzed with STEM and energy dispersive x-ray spectroscopy EDS on FIB lamellae from coated particleAGR1-632-035 enabling examination of the crystallo- graphic relationships on approximately 929 grain boundaries. Of these only 179 boundaries and triple junctions contained fission products and trans- uranic elements.Analyses of these grain boundary characteristics are in the final stages of interpretation and preliminary work already shows that using a high- angle annular dark-field scanningTEM HAADF-STEM is expedient to identify grain boundaries containing fission products. EDS was used to analyze at least qualitatively the composition of those fission products and PED was used to evaluate the grain boundary parameters in the SiC layer of irradiated TRISO particles. The final interpretation of these results and the integration of combined crystallographic and chemical analysis data still need to be completed to fully determine critical insight into the migration of fission products and transuranic elements through the SiC diffusion barrier layer.As an example of the level of information obtained one specific area Area B Sample IE 4 and an overview of the cumulative results from all areas are discussed in the following sections Area Bsample IEA total of 446 grain boundaries were analyzed in the five areas A to E of the IE sample Figure 4. However only results specific to the analysis of the grain boundaries inArea B are shown.The characteristics of these 51 grain boundaries were determined and reported in a 2015 summary paper for theAmerican Nuclear Society ANS 4. The crystallographic parameters of the grains surrounding the grain boundary fission product were collected using ASTAR. PED patterns were collected in a square grid with a 10 nm step size and spot size of