The characterisation and long-term evolution of rock salt is of critical importance across the energy industry due to its extremely low permeability, high thermal conductivity, and self-sealing (creep) behaviour under stress. Moreover, the viscoplastic nature of rock salt enables it to deform and flow over time, promoting the closure and self-sealing of transient fluid flow pathways (e.g., fractures or joints) over relatively short geological timescales, typically within tens of years. Countries such as Germany, the USA, and the Netherlands are actively investigating rock salt formations as potential host environments for repositories of higher-activity radioactive waste. In these repository concepts, crushed rock salt is typically employed as a backfill material and sealing medium for drifts, shafts, and cavities, capitalising on its creep behaviour to promote long-term self-sealing and containment performance.
In the UK, the Mercia Mudstone Group (MMG), which is comprised of a mixture of lithologies (mudstones, siltstones, sandstones, and rock salt) is known to provide an effective seal to dozens of oil and gas fields and is the caprock of the Liverpool Bay HyNet CCUS project. The Mercia Mudstone Group is also a potential host-rock for a geological disposal facility (GDF), which will permanently isolate the UK’s higher-activity radioactive waste. However, the effectiveness of the salt-bearing MMG, and crushed rock salt as an engineered barrier, under representative repository conditions (e.g., considering thermal and chemical perturbations from the GDF itself) is currently unknown.
To address this fundamental knowledge gap, the PhD student will be embedded within a vibrant research community, guided by international experts, and key industry sponsors and stakeholders, to study the effectiveness of natural and engineered ‘salty seals’ under representative repository conditions. The experimental programme will also have strong links (including visits) to the international ‘MEASURES’ research programme, with partners located in the Netherlands, Germany, and the USA.
Specifically, the PhD student will conduct experimental studies to assess the microstructural evolution and deformation processes in salt under realistic high-temperature, high-pressure, chemical, and fluid conditions. To capture salt evolution in 4D (3D + time), the student will be trained in the latest microscopy and CT-imaging techniques using bespoke facilities at the University of Manchester, as well as state-of-the-art national facilities, including the Diamond Light Source synchrotron facilities, and the Henry Royce Institute. Further, the student will provide inputs to the wider cutting-edge research community who will help extrapolate experimental outputs over GDF timescales (100’s of thousands of years) using the latest modelling techniques.
We envisage this exciting and collaborative PhD project will be suitable for a keen scientist with an interest in fields such as environmental science, chemistry, materials science, and/or applied mathematics, who have an interest in the UK and international nuclear sector. This project is co-funded by EPSRC Saturn Nuclear CDT, United Kingdom National Nuclear Laboratory
[https://uknnl.com], Nuclear Waste Services
[https://www.nuclearwasteservices.uk], and the School of Engineering at
University of Manchester [https://www.manchester.ac.uk ].
This project aims to address a significant knowledge gap by image-based characterisation of the behaviour of salt under representative repository conditions, with a focus on its sealing ability over multiple length scale (nm- cm) and temporal scales (seconds to days). The research will include laboratory testing of three material types (in priority order): 1) Crushed salt (used as backfill material), 2) Salt–clay mixtures (considered for engineered barriers or alternative hosts), 3) Intact salt (relevant to host rock behaviour). It will use multi-scale imaging and 4D imaging (3D + time) to investigate microstructural evolution and deformation processes in salt under realistic high-temperature, high-pressure, chemical, and fluid conditions. This innovative approach will generate insights into the fundamental science behind the sealing process, supporting model development and validation.
This project is co-funded by EPSRC Saturn Nuclear CDT, UKNNL (https://uknnl.com), and School of Engineering at University of Manchester (https://www.manchester.ac.uk ).
Supervisors
Dr Lin Ma -The University of Manchester
Dr Masoud Babaei - The University of Manchester
Dr Vasileios Tsitsopoulos - UKNNL
Dr Aislinn Boylan - UKNNL
Eligibility
Applicants should have, or expect to achieve, at least a 2.1 honours degree or a master’s (or international equivalent) in a relevant science or engineering related discipline.
How to apply
Our application process can also be found on our website: Apply | EPSRC Centre for Doctoral Training in Skills And Training Underpinning a Renaissance in Nuclear (SATURN) If you have any questions, please contact saturn@manchester.ac.uk
Equality, diversity and inclusion is fundamental to the success of The University of Manchester, and is at the heart of all of our activities. We know that diversity strengthens our research community, leading to enhanced research creativity, productivity and quality, and societal and economic impact.
We actively encourage applicants from diverse career paths and backgrounds and from all sections of the community, regardless of age, disability, ethnicity, gender, gender expression, sexual orientation and transgender status.
We also support applications from those returning from a career break or other roles. We consider offering flexible study arrangements (including part-time: 50%, 60% or 80%, depending on the project/funder).
Saturn_Nuclear_CDT
