Nuclear Science User Facilities 76 Figure 2. (a) STEM image; (b) precession electron diffraction derived ASTAR map, where the fission product precipitate highlighted in (a) with a red spot is located at a grain boundary indicated by a black line (the black line is drawn during ASTAR data analysis across the grain boundary so that the characteristics of the grain boundary are obtained); (c) EELS spectrum corresponding to the precipitate highlighted in (a); (d) zero-loss peak of the EELS spectrum corresponding to the precipitate highlighted in (a).