A new generation of superconducting magnets are vital for producing the magnetic fields for both fusion machines and particle accelerators. Nb3Sn is a low temperature superconductor which has been chosen for the upgrade of the Large Hadron Collider and as the magnetic coils for the next generation of fusion reactor, ITER. The next challenge for Nb3Sn is the Future Circular Collider, which will operate at 16 T, well beyond the 11.8 T specification of ITER. In order to engineer better performing wires it is vital to understand how the microstructure of Nb3Sn affects the superconducting properties. Atom Probe Tomography is an ideal technique to analyse atomic scale spatial-chemical composition of the grain boundaries and the variation in composition at different regions of the wire. Supporting work using Transmission Kikuchi Diffraction to analyse orientation and crystal structure variation within wires will be used to assess homogeneity across the wires. Samples with additions such as Ta, Ti, Zr and Hf have been provided by Florida State University for analysis. Furthermore, neutron irradiated samples will be analysed to see the differences in grain boundary structure and composition under irradiation, vital for a fusion reactor!