The BIGRAD project: Uranium nanoparticle formation under geological disposal relevant conditions

Beamtime at the Small Angle X-ray Scattering beamline (I22) at Diamond Light Source, funded through the Diamond - Manchester collaboration.

Abstract of research proposal:
The UK strategy for radioactive waste management is containment in a Geological Disposal Facility (GDF) in the deep sub-surface. Although U(IV) and U(VI) are insoluble in the alkaline environments surrounding a GDF, they can potentially be transported large distances as suspended nanoparticles, with implication for U containment. Here we will quantify the kinetics and mechanism of U(IV) and U(VI)- oxide nanoparticle nucleation and growth under relevant conditions. To achieve this, in situ time-resolved Small Angle X-ray Scattering experiments will be performed to:
(a) Quantify the mechanisms of the early stages of Ca-uranate (U(VI)) formation and growth from aqueous solutions across a range of relevant pH and ionic strength conditions;
(b) Study the precipitation of UO2 (U(IV)) and the effect of different reducing agents on the formation mechanism, kinetics and particle size.