Radionuclide alteration behaviour at the cement / subsurface interface: key controls on mobility

Nuclear Decommissioning Authority Bursary Studentship, Oct 2017. 3.5 years.

Katherine Morris, Sam Shaw and Jon Lloyd.
IntroductionThere is a substantial legacy of radioactively contaminated land at nuclear facilities in the UK (e.g. Sellafield, Figure 1). Options for its management and remediation include traditional dig and dump techniques which quickly become prohibitively expensive, or other innovative approaches. This PhD studentship is based around management of radioactively contaminated land and will focus on understanding the chemical form of radionuclides at the cement / subsurface interface – this is the critical zone where leaks from buildings interface with the natural environment. This will inform the long term fate of radionuclides on site, and also underpin whether concepts such as “in-situ disposal” of contaminated land are viable.
Project summaryThe project will focus on the behaviour of key radionuclides (Cs, Sr, U and Pu) in contaminated concrete matrices in the context of both their microstructural / mineralogical composition, and the speciation of radionuclides (RN) during their expected alteration. Experimental conditions will reflect real world contaminated land situations and will include relevant model minerals as well as materials from nuclear sites. Experiments will focus on radionuclide reactions during mineral alteration due to, for example, carbonation or redox alteration in the subsurface and latterly we will run targeted experiments examining radionuclide behaviour at the cement soil interface.
Wider contextThe PhD student will work as part of a vibrant team of 25+ researchers focussed on nuclear environmental sciences. They will receive state of the art training in radionuclide handling, chemical, mineralogical and biological analyses including aqueous chemistry, luminescence spectroscopy, electron microscopy, Raman, X-ray absorption spectroscopy including µ-focus fluorescence and diffraction techniques as well as microbial ecology techniques. Finally, the project is linked with collaborators (Wooyong Um and Carolyn Pearce) in the Geosciences Group at Pacific Northwest National Laboratory; there will be opportunities to visit PNNL as an Alternate Sponsored Fellow during the PhD.