Nuclear energy is a zero emission clean energy source with one of the smallest carbon footprints which produces more electricity on less land than any other clean energy source, such as windfarms. It is essential to our response to climate change and greenhouse gas emissions and meeting the energy gap. It currently provides almost a fifth of the UK’s electricity, generating waste that needs to be managed for safe, long term storage. While most radioactive waste comes from the generation of electricity, it is also a by-product of many medical and industrial activities that make use of radioactive materials. In a Geological Disposal Facility (GDF), higher-activity waste is stored hundreds of metres deep underground and GDF is internationally recognised as the safest long-term solution for this type of waste. There is an urgent need to understand how the cement grout used to contain waste interacts with the backfill material (called Nirex reference vault backfill) used to stabilise waste containers in the GDF in order to predict how the GDF will perform over thousands of years. This project investigates rare, aged samples (+10 years old) to determine how microstructural and physical characteristics of the Nirex reference vault backfill (NRVB): Portland cement grout interface will alter over time-scales applicable to deep geological disposal facilities. This project will use a combination of 2D X-ray diffraction and scattering, 3D/2D imaging and supporting analytical measurements to determine how the cements microstructure and porosity/permeability have developed over 10 years of hydrothermal ageing. Beamtime at Diamond Light Source, a national synchrotron facility, will be applied for to access a new small angle X-ray scattering technique called SAXS-Tensor Tomography for high resolution information on the microstructural changes. The results from this project will inform on further (future) work on radionuclide retention and reactive transport in NRVB, which requires a thorough understanding of porosity/permeability (and mineralogy) to support numerical/predictive models on radionuclide mobility. This project will directly inform on improving and developing the safety case for deep geological disposal of radioactive waste.

The successful candidate will be trained in and use techniques such as micro-(X-ray diffraction), electron probe micro-analysis, X-ray computed tomography and may access national facilities such as Diamond Light Source, to determine how mineralogy, micro-strain, porosity and permeability of the NRVB:cement grout interface have altered over 10 years. The student will be based in the Faculty of Engineering, one of the largest and most successful engineering faculties in the UK, and the largest in Scotland.