Nuclear Science User Facilities 14 Electron Probe Micro-Analyzer The EPMA is an electron beam instru- ment used primarily for high accuracy, in situ nondestructive chemical analysis of full cross sections of solid fuel and structural material samples.The EPMA acquires quantitative elemental analyses on relatively large samples at high spatial resolution (as little as one to two microns) using wavelength- dispersive spectroscopy.This informa- tion is used to understand elemental redistribution, the chemical behavior and migration of solid fission prod- ucts, fission gas behavior, and the impact of these phenomenon on fuel behavior and fission product release. Focused Ion Beam (FIB) and Scanning Electron Microscope (SEM) One of IMCL’s most versatile instru- ments is its combined FIB and SEM. The combination of the FIB and SEM allows three-dimensional reconstruc- tion that is important for under- standing material structure at the micrometer scale. The SEM uses a focused beam of high-energy electrons to generate a variety of signals at the surface of solid specimens.The signals that derive from electron-sample interactions reveal information about the sample including external morphology (texture), chemical composition, crys- talline structure and grain orientation. The primary use of the FIB is as a high-precision “knife” used to cut out small samples from areas identi- fied using SEM. By using the FIB, features often lost using traditional metallurgical sample preparation are preserved.These small samples are then subject to further analysis using a variety of methods. Electron Probe Micro-Analyzer Focused Ion Beam and Scanning Electron Microscope