The safe storage of spent nuclear fuels is a complex challenge that belies a simple solution. The biggest scientific challenge is that storage must be over long periods of time, and knowledge of how the complex and interlinked chemistry changes is important to build robust safety cases for underground storage. One important uranium compound is studtite, [UO2(O2)(H2O)2].2H2O which dehydrates to metastudtite [UO2(O2)(H2O)2]. There are subtle structural changes that may impact on the chemical behaviour. In this project we aim to look at the dehydration using powder neutron diffraction to precisely locate the light atoms (oxygen and hydrogen) and explore these structural effects.