Ion Beam Irradiation for High Level Nuclear Waste Form Development (INWARD)

The safe long term disposal of high level nuclear waste from reprocessing has proven to be problematic worldwide with few countries having a long term strategy. This may be due to a range of reasons, ranging from technical to socio-political in nature. Issues remain, including the fabrication and the long term behaviour of high level waste forms during geological storage. This project addresses the nature of such challenges, focusing on the long term behaviour of proposed waste forms and the impacts arising from induced radiation damage, through alpha and beta decays.  Radiation damage induces change over long timescales, i.e. hundreds to millions of years, making long term effects difficult to examine. However, the accelerated damage produced by ion beams provides a method for developing predictive models that can then be verified and tested; conditions such as temperature, rate of damage, in situ testing can all be controlled during ion beam irradiation. Materials of interest include the international standard glass and pure silica glass; zircon; pyrochlore–fluorite ceramics and a representative glass composite. Where available, the results will be validated using synthetic and natural samples that have undergone differing degrees of damage due to self-irradiation. The knowledge will be used to identify and quantify mechanisms of material transformations, and the long term predictability required for geological repositories. The results will define the source terms for waste forms in evolving repository designs, enhancing the design and reducing uncertainty and costs.