Treatment of degraded nuclear fuels

This project will support the programme to immobilise the UK plutonium stockpile, through an investigation of natural analogue and synthetic actinide hosts, developing new insight utilising X-ray Absorption Spectroscopy, in three key respects. First, the speciation of uranium in pyrochlore related minerals will be investigated with spatial resolution XAS, combined with bulk average XAS, to establish the role of higher uranium oxidation states in charge compensation, and long term stability. Second, the evolution of the local structure, and uranium speciation, as a function of damage will be investigated through controlled recrystallization of metamict minerals, to understand the long term impact of radiation damage on actinide retention. Third, the hypothesis of radiogenic oxidation, associated with actinide alpha decay, will be probed using bulk and spatially resolved XAS characterisation of lead daughters, combined with Laser Ablation ICP-MS and EPMA analysis to date specimens and establish the radiogenic character of incorporated lead. The project will also explore the synthesis and characterisation of ceramic and glass-ceramic counterparts and compare their response to radiation damage by XAS studies of ion beam irradiated materials. The project will be undertaken in collaboration with synchrotron light sources (DLS, SLS, NSLS) and the Australian Nuclear Science & Technology Organisation.