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Implications of U(IV)-silicate core-shell colloids for radionuclide transport


EMSL Project ID
49774

Abstract

Here we will use a range of techniques to advance fundamental and predictive understanding of uranium colloids in the subsurface environment. Recent work has highlighted that U(IV)-silicate colloids can form under a range of scenarios relevant to spent nuclear fuel storage at nuclear mega sites such as Hanford, USA and Sellafield, UK, and contaminated land / geological disposal1,2 systems, and have the potential to enhance the mobility U(IV). This is particularly relevant in management and clean-up of nuclear facilities and in long-term radioactive waste disposal. Although U(IV)-silicate colloids have the potential to be a significant factor in radionuclide transport across multiple scenarios, their exact structure is not well understood, but will be essential in understanding and predicting their subsurface environmental behaviour.

Our recent work has indicated that U(IV)-silicate colloids may have a core-shell structure, with a uraninite-like UO2 core and amorphous silica coating. Here we propose to use EMSL facilities to undertake experimental investigations using 29Si MAS NMR, XPS and STEM coupled to DFT calculations to define the molecular scale structure of these colloids. The facilities and expertise at EMSL are essential to understanding this molecular structure. The molecular scale information provided by this application will be essential in predicting the physical and chemical properties of these colloids in a range of terrestrial subsurface environments including their transport behaviour and subsequent implications for contaminant fate.

Project Details

Project type
Large-Scale EMSL Research
Start Date
2017-12-08
End Date
2019-09-30
Status
Closed

Team

Principal Investigator

Samuel Shaw
Institution
University of Manchester

Co-Investigator(s)

Carolyn Pearce
Institution
Pacific Northwest National Laboratory

Team Members

Luke Townsend
Institution
University of Manchester

Katherine Morris
Institution
University of Manchester

Thomas Neill
Institution
University of Manchester

Kevin Rosso
Institution
Pacific Northwest National Laboratory

Related Publications

Neill T.S., K. Morris, C. Pearce, L. Abrahamsen-Mills, L. Kovarik, S. Kellet, and B. Rigby, et al. 2019. "Silicate stabilisation of colloidal UO2 produced by uranium metal corrosion." Journal of Nuclear Materials 526. PNNL-SA-146561. doi:10.1016/j.jnucmat.2019.151751