Deep geological disposal concepts are preferred solutions for the long-term management of high- level radioactive waste (or higher activity waste) in many countries. Clays rich in smectite minerals (e.g. bentonite) are candidate material for the buffer, backfill and sealing systems in such concepts and play critical functions in the overall safety. The groundwater composition of the geological disposal facility (GDF) can undergo significant changes when it infiltrates through the clay barriers. Understanding the hydro-geochemical changes of groundwater and the clay-water interactions are critical to assess the performance of the barrier for various reasons (e.g. evaluating the re-saturation time, swelling pressure, hydraulic conductivity, and retardation of corrosive species).
A number of experimental studies and numerical investigations on hydro-geochemical evolution of clay-barriers have been presented in the last 15 years. However, there are still critical gaps which limit prediction capability and applicability of the experimental works for validation of reactive transport models. In this project, the hydro-geochemical modelling of pore water evolution of compacted bentonite will be fundamentally revisited and tested against new experimental data which will be generated in this PhD. The aim is to develop a new paradigm of modelling and set of robust experimental data that can capture processes involved in clay-water interactions more accurately. The emphasis is on reactive transport processes in clay barriers under saline groundwater infiltration and elevated temperature effects.
The work will include a series of experiments to reveal the behaviour of the representative volume element of bentonite under infiltration of saline solutions (at ambient and elevated isothermal temperature). The results will be combined with the theoretical advances in geochemical modelling to develop a new or improved reactive transport models.
The successful candidate will join the Geoenvironmental Engineering Research Group at the University of Manchester (https://www.manchester.ac.uk/). The project will jointly be supervised by a team based in the Department of Mechanical, Aerospace and Civil Engineering at the University of Manchester (https://www.mace.manchester.ac.uk/) and the National Nuclear Laboratory (https://www.nnl.co.uk/). The PhD will be hosted by the GREEN CDT based at the University of Manchester (https://www.nuclear-energy-cdt.manchester.ac.uk/). The successful candidate will also be affiliated to Research Support Office (RSO) of the UK’s Nuclear Waste Services (NWS) (https://www.research-support-office-gdf.ac.uk/); through which they will access RSO training and be part of the RSO Community supported by the experts from NWS.
The project is funded for 4 years and open to home and overseas students. This is a unique opportunity to develop a strong research profile, working closely with experts at the University of Manchester, National Nuclear Laboratory and Nuclear Waste Services.
Candidates with experimental or/and numerical research experiences in hydro-geochemistry, reactive transport processes, geo-environmental engineering and soil science or other relevant areas are particularly encouraged to apply.