Impact of an alkaline microbiome on the mobility of uranium under conditions analogous to cementitious nuclear waste disposal

Radioactive Intermediate Level Waste (ILW) is heterogeneous, containing radionuclides and a range of organic and inorganic materials encapsulated in cement, destined for disposal in a deep geological disposal facility (GDF). A range of organic waste materials contained in ILW, e.g. gluconic acid or isosaccharinic acid (ISA), show chelating abilities with some radionuclides. Of particular interest uranium and its fate, as it forms water-soluble complexes with gluconic acid and ISA. The organic chelates also have the potential to be metabolised by alkaliphilic microbial communities, which can in turn influence the fate of radionuclides. Alkaline sediments were supplemented with gluconate or ISA and U(VI), to explore the fate of organics and uranium in a system analogous to an evolving GDF.