The aim of this proposal is to develop a methodology to investigate multicomponent glass structure, combining neutron diffraction, XRD, NMR, ab initio MD, and RMC. We wish to use this methodology to investigate the relationship between structure and chemical durability of HLW glass. HLW (High Level Waste) glass is the internationally accepted means of immobilizing and storing high level radioactive nuclear waste. Glass is used for this purpose due to its ability to incorporate a wide spectrum of elements over a wide range of composition, its resistance to radiation damage, its long-term durability, and the relatively simple production process. For the long term safety assessment of HLW glass, it is essential to understand how the addition of modifier ions affects the structure and hence the chemical durability of the glass, and this is the ultimate aim of our study.