[EPSRC - iCASE] Microbe – radionuclide interactions in legacy nuclear waste systems

Recent work in the Geomicrobiology Group at the University of Manchester has shown that microorganisms can have a controlling impact on the speciation (and hence mobility) of key radionuclides in a broad range of natural and engineered systems. Working closely with the iCASE sponsor NNL, this EPSRC iCASE project will examine the role of microbes in controlling the speciation and fate of radionuclides in high pH ILW waste sludge and fuel storage pond systems at nuclear sites such as Sellafield.

The inventory of Sellafield’s legacy pond and silos facilities is varied and complex, including a range of corroded metal sludges, spent fuel and other materials. Consequently, the chemistry of actinide species (originating from exposed spent fuel) in these ponds is complicated and will be subject to a range of biogeochemical processes. While it is known that a number of the legacy ponds contain active biological material, the influence of microbial species on actinide chemistry in these systems is currently not well understood. Microbial processes are known to affect actinide mobility through controlling their oxidation state and co-ordination chemistry, however, it is only recently that investigations of these processes have begun at high pH using bacteria that have evolved to survive under strongly alkaline conditions that are encountered in fuel storage systems.
The proposed PhD project will build on recent and ongoing research at the University of Manchester and NNL, including molecular-scale (multi-omics) microbial characterization, alongside recent advances in spectroscopic characterisation of actinides in biogeochemical systems. Recent collaborative research has also shown the importance of colloids (small, non-settling particulates) in controlling actinide behaviour in these systems, and this project will complement a number of ongoing research council and commercially-funded research programmes. The results will be of fundamental interest to the wider environmental community, and have direct relevance to a number of nuclear site operators in the UK and abroad.
The studentship will be under the supervision of Profs. Jon Lloyd, Kath Morris and Sam Shaw (School of Earth and Environmental Science, SEES) and Dr. Louise Natrajan (Centre for Radiochemistry Research, CRR). Industrial supervision will be provided by Dr Sean Woodall at NNL. The School of Earth and Environmental Sciences (SEES) at the University of Manchester supports cross-disciplinary education and research in the geosphere, biosphere, atmosphere and hydrosphere. With a staff of more than 300, SEES offers a vibrant postgraduate research environment, with approximately 200 registered PhD students. The student will be based primarily in Williamson Research Centre for Molecular Environmental Sciences (WRC) which is housed within SEES. The WRC has the UK’s only purpose designed suite of radiochemistry, geochemistry and environmental mineralogy and microbiology laboratories (and associated infrastructure), which will be available for the student. The student will also have access to specialized radionuclide imaging and spectroscopy facilities in the Centre for Radiochemistry Research, CRR. The Manchester group has extensive expertise in geomicrobiology, mineral and colloid analysis, geochemistry, X-ray absorption spectroscopy and its application to speciation of radionuclides / stable elements in complex environmental samples, and we expect to use all of these approaches for this study. The group has also pioneered the use of molecular ecology techniques for the analysis of complex biogeochemical experiments in radionuclide contaminated soils and water, and these approaches will be used for biomaterial analyses. We anticipate that the project would also include a placement at NNL Central Laboratory. This will allow the student to perform research on trans-uranic samples at NNL’s specialist facilities and potentially study highly active plant samples, a unique opportunity in the UK. It will also give them the opportunity to work in an industrial research environment. The student will also spend time with the NNL Effluents and Environmental Chemistry team to benefit from their experience in modelling techniques. Developing numerical models of biogeochemical processes is an important part in making predictions about long-term waste evolution.
This project would be well suited for candidates with an interest in multidisciplinary science and a strong background (BSc or MSc) in environmental science, (micro)biology, chemistry or related subjects. The training given will prepare the student for a career in academia or industry.