The impact of polyacrylamide radiolytic and microbial degradation products on the interim and long term storage on radwaste

Polyacrylamide has been identified as a potential settling aid which can improve sludge settling operations by flocculating a range of legacy fuel materials on the Sellafield site. Microbes break down polymeric material into substrates which may potentially be consumed by methanogens, producing methane and carbon dioxide. Polyacrylamide is expected to increase the microbial population and increase the generation of such gases, while also providing radiolytic and biological degradation paths to produce material which could chelate and mobilse radionuclides sentenced to a long-term geological disposal. Understanding the radiolytic and microbial degradation products and kinetics will inform engineering design capability, and inform decommissioning and disposal stakeholders how to apply and manage risk regarding the application of such reagents in nuclear decommissioning operations.

This interdisciplinary research project will combine geomicrobiology, microbial genomics, organic chemistry, radiochemistry, and radiation science, and will study polyacrylamide (bio)degradation in batch laboratory incubations using state of the art techniques including microbial and DNA sequencing analysis, light and electron microscopy, XRF, XAS, confocal microscopy, ESEM, and TEM. The successful applicant will join a welcoming cohort of 40+ interdisciplinary researchers working in two recently refurbished and co-located centres in the Dept of Earth and Environmental Sciences, co-directed by the PI and co-supervisors (Lloyd, Morris, van Dongen and Shaw). The student will have access to a large suite of dedicated laboratories within the Williamson Research Centre for Molecular Environmental Sciences (WRC; directed by Lloyd), which houses state of the art equipment for molecular environmental studies and sits alongside the new £4M NNUF RADER labs (https://www.nnuf.ac.uk/rader) directed by Morris, offering unique complementary facilities for handling and analysing radionuclides in nuclear environmental systems. The student will also benefit from links to the Dalton Cumbrian Facility (DCF) for irradiation studies on polyacrylamide.