The safe storage of spent nuclear fuels in an underground repository requires the fundamental chemistry to be well understood so predictions of solubility behaviour over 100,000 years can be reliably made. However even simple data such as solution behaviour of uranium compounds has not been conclusively proven. For example, X-ray spectroscopy has been found to be model dependent and different conclusions can be found from very similar data. Solid state structures are known but this does not necessarily give solution phase structures. One are where hydration is important is in the separation of lanthanides and actinides in the Partition & Transmutation strategy for treating nuclear wastes. In this proposal the key objectives are to explore the solution phase structures of uranium in three different oxidation states using neutron diffraction at the Sandals beamline.