Funded PhD research projects

Applications are invited from candidates interested in an NWS sponsored PhD project.

As an NWS RSO student you will be conducting world leading, high quality, and relevant research to underpin the NWS geological disposal programme.  Your PhD research will address gaps and uncertainties relevant to the design and development of a Geological Disposal Facility (GDF), potentially the most significant environmental infrastructure project in the UK. Throughout your research project you will be supported by the NWS RSO with professional networking opportunities, support to publish your work and opportunities to present at relevant conferences. If you want to undertake impactful research, consider one of the fully funded PhD projects below. More research projects will be added to this page regularly as funding becomes available. Sign up to our newsletter to be kept up to date.

PhD projects starting in 2022 mark the second cohort of NWS RSO research students. The NWS RSO will offer additional training and support, as well as access to a network of researchers working on all aspects of geological disposal.

If you are interested in one of the fully funded PhD projects below, click on the title of the project to get further details. Please get in touch with the supervisor for more information on how to apply.

A framework for modelling groundwater flow in deep heterolithic sedimentary sequences

Title: A framework for modelling groundwater flow in deep heterolithic sedimentary sequences

Description:

Energy security and climate change are two of the most import challenges of the 21st century. Nuclear energy and the safe disposal of radioactive waste will play a key role in meeting these challenges. Numerate geoscientists are needed to help manage the risk associated with the deep disposal of radioactive material. This will be achieved using an underground Geological Deposal Facility (GDF), which is based on the multiple barrier concept. One of these barriers is the geosphere or the geological environment of the host and surrounding rock formations. Therefore, understanding the movement of groundwater in these formations and its effect on radionuclide transport is vital to the development of operational and postclosure safety cases.

The Mercia Mudstone Group (MMG) is currently being considered as a potential host rock for a GDF. This formation, however, has not been investigated to the same extent as other potential host rocks. There is a need, therefore, to develop hydrogeological models of the MMG and adjacent rocks in the North East Irish Sea Basin (NEISB). This will be the focus of the PhD, which will use data collection to construct a conceptual 3D stratigraphic ground model. This, in turn, will be converted into a dynamic numerical model using the Imperial College Finite Element Reservoir Simulator (IC-FERST). This state-of-the-art numerical code will be used to explore the controls on groundwater flow in the context of radionuclide movement, along with the effects of data uncertainty under current and near future climates.

Institution: Imperial College London

Supervisor(s): Prof Adrian Butler, Dr James Lawrence and Prof Matt Jackson

Sponsor(s): Nuclear Waste Services and EPSRC CDT in Nuclear Energy Futures

Application of deep learning to characterise transport of waste-derived gas in Lower Strength Sedimentary Rocks (LSSRs)

Title: Application of deep learning to characterise transport of waste-derived gas in Lower Strength Sedimentary Rocks (LSSRs)

Description:

This is a 4-year PhD project funded by Nuclear Waste Services after a competitive call for PhD bursary. The topic of research is on use of machine learning for characterising the complex transport of gas in LSSRs. Hydrogen developed from anaerobic corrosion of the steel canisters and other iron-containing structures and from the radiolysis of water due to radioactive decay, will trigger a complex flow problem where hydrogen transports in water-saturated heterogeneous clay pore space. Different physical processes are incurred such as diffusion of H2, uptake or adsorption of the gas on rock surface, as well as interactions with clay host rock. Additionally, clays feature extensive level of mineralogical and physical (pore space) heterogeneity. Existing literature have showed that experiments and flow modelling (based on classical numerical methods) of these processes are computationally expensive. Therefore, we propose firstly to use machine learning and pattern recognition to construct a set of databases for various clay rock features. This will be done in tandem with x-ray microtomography and utilising existing literature images.

Main objectives:

  • Stochastic compilation of a large database of machine learning, pattern recognition and x-ray micro-CT based realisations of clay rock mineralogical and pore space maps for use in modelling.
  • Image based modelling of single and two-phase waste-derived gas transport in water for sedimentary rock samples.
  • Deep learning (Convoluted Neural Network)-based characterisation of regimes of gas transport (adsorption/uptake, diffusion and reactive with surrounding clay) in single- and two-phase conditions for varying rock minerals and pressure and temperature.
  • Machine learning-based risk analysis of long-term radionuclides fate within multiscale mineralogically heterogeneous clay systems with various pore features specific to clay.

Institution: University of Manchester

Supervisor(s): Dr Masoud Babaei, Dr L Ma

Sponsor(s): Nuclear Waste Services

Effects of Coastal Change in the selection of a Geological Disposal Facility

Title: Effects of Coastal Change in the selection of a Geological Disposal Facility

Description:

Geological disposal of radioactive waste is one of the UK’s largest environmental protection projects. It aims to provide a safe and secure long-term solution for the disposal of higher activity radioactive waste. As such, environmental change represents an important consideration regarding the siting process and post-closure safety.

More specifically, areas within or close to the coastal zone are subject to significant environmental forcing and are continuously evolving. Even within a single year, tidal and wave forcing can lead to significant changes in the location of the shoreline and seabed profile. Recent climate projections indicate that changes in the mean sea-level, ocean circulation and storminess will have a profound effect on coastal dynamics in the longer term. This means that many areas will experience considerable geographical modifications. Such effects are already becoming apparent through increased rates of erosion and more frequent occurrences of coastal flooding. These processes can potentially have a significant impact on the viability of a Geological Disposal Facility (GDF).

Present projections from the International Panel for Climate Change (IPCC) provide predictions on climate changes for the next hundred(s) years. These largely indicate that anthropogenic emissions have a dominant role in driving global warming, sea-level rise, and subsequent coastal erosion. Considering that the lifetime of a GDF extends to 100,000-200,000 years, present climate information represents only short-term effects. Over longer time scales additional considerations regarding the global state of the climate arise (e.g., land-level changes and global ocean circulation changes). These considerations require a deeper understanding of the physical system and a better description of the future state of the biosphere.

The purpose of the present project is to develop methodologies appropriate to the description of coastal evolution under a changing climate around the UK. This will be achieved by a combination of improved physical understanding of the coastal system and advanced statistical and numerical techniques. In integrating the detailed modelling of coastal processes into long-term climate prediction, the research outcomes will provide the necessary tools to predict coastal change in time scales ranging from 100s to 100,000s years. The main objectives of the project are summarised as follows:

• Develop process-based simulations of coastal change using dynamically downscaled global climate around UK coasts.

• Incorporate human interventions (coastal protection structures) and additional sediment source/sink terms in coastal evolution modelling.

• Dimensional reduction of morphodynamic loops using improved physical understanding and advanced statistical methods (surrogate modelling, storm sequencing).

• Provide am improved representation of coastal change in short-term time scales (100s of years) under climate change scenarios obtained from IPCC predictions. Integrate the short-term methodology into long-term predictions (100,000s of years). 

• Quantify the uncertainty in models.

This information will provide critical insights regarding the selection and assessment of coastal sites as potential Geological Disposal Facilities and provide a sound basis for assessing their safety in the long term.

Institution: Imperial College London

Supervisor(s): Dr Ioannis Karmpadakis, and Dr James Lawrence

Sponsor(s): Nuclear Waste Services, EPSRC NEF CDT

Effect of ground water composition on the design of a nuclear waste disposal facility

Title: Effect of ground water composition on the design of a nuclear waste disposal facility

Description:

Nuclear energy currently forms around 20% of UK’s electricity supply and will be one of the main clean energy sources to underpin the Government’s target of net zero carbon emission by 2050. The safe disposal of nuclear waste, comprising not only the newly created waste but also the existing 5 million tonnes of waste at different levels of radioactivity, is key to this strategy. The UK Government is committed to delivering a geological disposal facility (GDF) as an internationally accepted long-term solution for sustainable management of nuclear waste. This is envisaged to be one of the largest environmental projects ever undertaken, with a facility constructed 0.5 to 1 km below the ground surface and with an estimated 15-20 square kilometres footprint.

The GDF concept encompasses deposition of canisters of waste deep underground, in depositional holes excavated in a suitable geological formation. To manage the environmental risk associated with this disposal concept, the design of the disposal solution requires multiple barriers, one of which is emplaced between the canister and the host formation in the form of compacted unsaturated bentonite clay when initially installed in a deposition hole. Its purpose is to protect the canister from corrosion and to retard migration of contaminants that may leak from a failed canister. The nature of unsaturated soils is that their voids are infilled with both water and air. The function of a bentonite buffer is to become saturated during the GDF lifetime, by receiving water from the surrounding natural host environment. This process enables the bentonite to swell, promoting the sealing of any construction gaps and, ultimately, saturation and homogenisation of the buffer. The main challenge in this process is to quantify the long-term interplay between the dual porosity of compacted bentonite, comprising macro-porosity, as the void space between compacted clay aggregates, and micro-porosity, as the void space within the clay aggregates. Recent experimental research1, in particular using Mercury Intrusion Porosimetry (MIP), has demonstrated that the initial distribution of bentonite’s dual porosity depends on its initial state (stresses, dry density, suction), while the final state upon saturation can show either a single or a double porosity. Additional factors in this hydro-mechanical (HM) coupling are the temperature imposed by the energy generated in the canister, making it a thermo-hydro-mechanical (THM) process, and the composition of the ground water, which extends it to a THM-chemical process (THM-C). Most of the research conducted to date has examined the interaction of compacted bentonite with fresh water.

Proposed research and research methodology
To address the gap in knowledge of how different solutes in the ground water may affect the evolution of porosity in the bentonite barrier, advanced numerical modelling will be performed as part of this PhD research. The bespoke finite element (FE) software ICFEP2 (Imperial College Finite Element Program) will be employed, which is a world-class computational facility for state-of-the-art modelling of geo-materials. The software has a fully coupled THM formulation for saturated3 and unsaturated4 soils and a dual-porosity constitutive model5 (Imperial College Double Structure Model, ICDSM). This formulation has been successfully applied in the THM simulations of laboratory element tests and full-scale field experiments6 conducted at temperatures of up to 100oC in fresh water, as part of the Euratom BEACON project. This THM formulation is currently being extended to take account of vapour flow for the modelling of the HotBENT full-scale experiment, in which the bentonite buffer is exposed to temperatures of up to 200oC.

The THM-C development envisaged for the proposed project will be conducted in conjunction with the appropriate experimental data to characterise the behaviour of compacted bentonite exposed to different ground water composition. The data will be sourced from literature, from collaboration with the British Geological Survey (BGS, Dr Jon Harrington), from the BEACON project and at a later stage also from the HotBENT project. The project aim is to deliver a robust THM-C coupling procedure for predictive computational modelling of long-term bentonite barrier evolution, which will underpin the safe design of nuclear waste disposal facilities.

 

Institution: Imperial College London

Supervisor(s): Prof. Lidija Zdravkovic, Prof. David M. Potts, Dr Jon Harrington (BGS)

Sponsor(s): Nuclear Waste Services, EPSRC NEF CDT

Geological Fate and Impact of Isosaccharinic acid (Geo-FISA)

Title: Geological Fate and Impact of Isosaccharinic acid (Geo-FISA) 

Description:

The nuclear fuel cycle has generated higher-level radioactive wastes that will be disposed of in a deep geological facility (GDF) that will provide multiple barriers to the migration of radionuclides to the surface over prolonged timescales (tens of thousands of years). Isosaccharinic acid (ISA) is an organic ligand that is produced from the abiotic hydrolysis of cellulosic material found in Low Heat Generating (Intermediate Level Radioactive) Wastes (LHGW) [1]. Our studies showed that microbes can degrade ISA under GDF-relevant conditions [2] and this process can lead to the precipitation of priority radionuclides [3].

This is an interdisciplinary research project combining geomicrobiology, microbial genomics, radiochemistry and mineralogy, and will study ISA degradation in dynamic flowthrough systems using state of the art techniques including shotgun metagenomics, 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 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.

Academic background of candidates

Applicants are expected to hold, or about to obtain, a minimum upper second class undergraduate degree (or equivalent) in Chemistry, Environmental Chemistry, Geosciences, Microbiology or a closely related discipline. A Masters degree in a relevant subject is highly desirable and experience in handling and analysis of environmental samples is also desirable.

Application Enquiries

To apply please send a cover letter and CV to Jonathan Lloyd (Jon.lloyd@manchester.ac.uk), Naji Bassil (Naji.bassil@manchester.ac.uk)

To apply please visit: https://www.ees.manchester.ac.uk/study/postgraduate-research/how-to-apply/

Please search and select Environmental Science (academic programme) and PhD Environmental Science (academic plan)

Institution:  University of Manchester

Supervisor(s): Jonathan Lloyd, Naji Bassil, Sam Shaw, Katherine Morris, Tom Neill

Sponsor(s): Nuclear Waste Services, GREEN CDT

 

1. Glaus MA, Van Loon, LR. 2008. Degradation of cellulose under alkaline conditions: New insights from a 12 years degradation study. Sci. Technol. 42:2906-2911

2. Bassil NM, Bryan N, Lloyd JR. 2014. Microbial degradation of isosaccharinic acid at high pH. ISME J. 9:310-320

3. Kuippers G, Morris K, Townsend LT, Bots P, Kvashnina K, Bryan ND, Lloyd JR. 2021. Biomineralization of uranium-phosphates fueled by microbial degradation of isosaccharinic acid (ISA). Sci. Technol. 55:4597-4606

Lithologic, sedimentology, stratigraphic and diagenetic controls on the gas transport properties of the Mercia Mudstone Group

Title: Lithologic, sedimentology, stratigraphic and diagenetic controls on the gas transport properties of the Mercia Mudstone Group

Description:

Radiogenic gas escape from a Geological Disposal Facility (GDF) can happen in several ways, such as advectively via aqueous fluids, or as a separate gas phase. Consequently, fluid movement associated with any GDF must be understood before site selection is finalised. The Mercia Mudstone Group (MMG) is a target for a UK GDF; previous work at Liverpool has shown its low permeability is related to primary sedimentology and diagenetic history. Clay-rich horizons represent a better prospect for siting a GDF, but permeability has not yet been extensively measured, nor the principal controls on fluid migration established. This studentship will establish a quantitative understanding of the controls of gas and water permeability under conditions that are directly representative of those predicted for the GDF. It will determine how stratigraphy, sedimentology, mineralogy, petrography, pressure and temperature histories affect the flow characteristics (porosity, pore throat diameter, and gas and water permeability) of the non-evaporitic Mercia Mudstone Group, providing a firm basis to understand the pathways for radiogenic gas migration from a GDF that will affect the stress and temperature conditions in the subsurface.

The student will be trained in a range of techniques that will yield a full characterisation of the MMG rocks under a wide range of conditions. The controlling factors on the gas and water permeability of the MMG rocks will be identified by an integrated analysis of the datasets through principal component analysis. The following provides an overview of the various samples, techniques and datasets that will be assembled during the project.

The first objective will be to establish a set of samples that reflect the stratigraphic and geographic variability of the clay-rich horizons of the MMG. The petrography and mineralogy of the suite of samples will be fully characterised and quantified using a range of analytical facilities including light optics, XRD, SEM, and FTIR.

We will prepare samples to experimentally measure the permeability to gases. CO2, CH4 and Ar will be our initial targets, as CO2 and CH4 are carbon-bearing gases (significant for 14C flux) and Ar is a noble gas with parallels to radon. At very low gas permeabilities, Klinkenberg corrections may be needed but data from the range of gases proposed will allow this calculation for other, similar, gases including H2 and He. Water permeability will also be measured, as gas dissolved in ambient aqueous pore fluids can be advectively transported away from the GDF. For all permeability measurements, we will measure the permeability under varying (a) pressure and (b) temperature conditions. In the case of aqueous pore fluids, even small temperature changes can destabilise adsorbed water on clays in pore throats, significantly increasing overall fluid flux6. Permeability will be measured using the transient pulse and oscillating pore pressure techniques so that spot measurements can be taken as well as continuous measurement to monitor permeability evolution with temperature6. Experimental conditions will be tailored to the likely range of pressures and temperatures anticipated for the GDF, confining pressures up to 50 MPa and temperatures not exceeding 150°C.

The mean pore throat diameters of samples will be measured using mercury injection porosimetry. While the porosity of many MMG rocks seem to be similar, the permeability is often dictated by the mean pore throat diameter1,3. This key additional measurement will provide a better understanding of the fluid flow properties of the rocks.

The wide range of datasets produced will be integrated to provide a firm basis to quantitatively predict the permeability of the various stratigraphic intervals in the MMG (and linked to core sedimentology and wireline log data for context and up-scaling) according to not only the specific rock properties such as mineralogy, porosity, and pore throat diameter, but also the evolving environmental factors such as pore-fluid chemistry and temperature evolution. This will provide a solid basis for a quantitative prediction of the long-term fluid circulation around a GDF that will affect the stress and temperature conditions in the subsurface.

For any enquiries, please contact Professor Dan Faulkner on: 

To apply for this opportunity please visit: https://www.liverpool.ac.uk/study/postgraduate-research/how-to-apply/ and click on the ‘Ready to apply? Apply online’ button, to start your application.

Institution: University of Liverpool

Supervisor(s): Dan Faulkner, R Worden, Q Fisher

Sponsor(s): Nuclear Waste Services

Stress-induced creep and stability in Mercia Mudstone: influence on long term stability of underground excavations

Title: Stress-induced creep and stability in Mercia Mudstone: influence on long term stability of underground excavations

Description:

Engineering solutions for deep geological disposal of radioactive waste requires a challenging combination of knowledge: on one hand, how structures such as tunnels and caverns within a rock mass modify the local/regional stress state, and on the other hand, how these structures respond to in-situ stresses over century to millennium timescales. In all cases, pre-existing discontinuities (faults, fractures, interbedding and joints) and complex lithology (e.g. clay-rich zones and/or mudstone-halite interbeds) may significantly modify these responses which in turn are again modified by the presence of fluids and/or temperature. To design structures with long-term stability this project will test a series of natural Mercia Mudstone samples using high force hydraulics to simulate real-world stress fields. Samples will be monitored via strain meters and microseismic sensors in the presence of temperature and fluids. Data from these calibrations will build a new understanding of the short-term (weeks to months) to long-term (centuries) stability of structures by integrating these new data into an initial numerical model to incorporate the effect of destabilizing discontinuities and extrapolate to design scale and timescales. The project will also explore feedback(s) between rock mass damage evolution at elevated temperature/stress, and how water flows through the rock structure.

The project will be guided by a multidisciplinary team with expertise in rock physics, rock mechanics, geotechnical numerical modelling, and geological engineering. The team includes researchers at the University of Portsmouth, the BGS (providing access to recovered rock cores from the Mercia Mudstone Group), and engineering design experts at Ramboll.

Institution: University of Portsmouth

Supervisor(s): Dr Philip Benson, Dr Nick Koor, Dr Arash Azizi

Sponsor(s): Nuclear Waste Services, BGS and Ramboll

Understanding the consequences of steam formation for the sealing performance of barrier bentonites

Title: Understanding the consequences of steam formation for the sealing performance of barrier bentonites

Description: This project will investigate the effects of steam formation within partially saturated bentonite and its subsequent performance on the engineered barrier system. Maintaining and demonstrating an adequate Engineered Barrier System sealing performance will be of fundamental importance to safety assessments for the disposal of HHGWs. This PhD will specifically address two key questions: (i) whether the interaction between partially saturated bentonite and steam results in a marked reduction in the bentonite swelling capacity, and (ii) whether the bentonite permeability is increased as a consequence.

The PhD will answer these questions by conducting a series of experiments in bespoke testing apparatus at the British Geological Survey (BGS) to establish the swelling capacity and permeability of steam treated bentonites under a range of repository conditions. Laboratory experimentation will be conducted both within the Transport Properties Research Laboratories at the BGS and using the state-of-the-art facilities at the University of Bristol Interface Analysis Centre, at which the student will have membership.

Institution: British Geological Survey and University of Bristol

Supervisor(s): Dr Katherine Daniels and Prof Tom Scott

Sponsor(s): Nuclear Waste Services

Uranium and U-series radionuclide behaviour in phosphate-based cement systems – underpinning safe disposal of nuclear waste

Title: Uranium and U-series radionuclide behaviour in phosphate-based cement systems – underpinning safe disposal of nuclear waste

Description: 

Disposal of nuclear legacy waste is one of the biggest scientific and engineering challenges of the 21st Century. Geological disposal of nuclear waste in a repository 200-1000 m below ground is internationally considered to be the preferred long-term solution for radioactive waste disposal. A key feature of a geological disposal facility (GDF) is the backfill material which acts as both a physical and chemical barrier to the migration of radionuclides such as uranium. Research into backfill materials is essential for safe and efficient disposal of wastes. In this context, phosphate based cements (PBCs) are a novel and promising candidate for depleted, natural and low-enriched uranium waste disposal due to the likely formation of highly insoluble U(IV) and U(VI) phosphates. This fully funded experimental project will investigate the effectiveness of these PBC backfill materials for immobilising uranium by probing the reactions of key uranium species and uranium radioactive decay products with phosphate based cement leachates (PBCL).

This project will involve fundamental, interdisciplinary research combining radiochemistry, environmental radioactivity and mineralogy with cutting edge techniques in a state of art facility. The research project will be carried out in the University of Manchester’s RADER lab facility, and will include characterisation and development of PBCL, exploring the short and long term effects of PBCL on uranium speciation / solubility and reactivity using different disposal relevant uranium materials. The research will also apply thermodynamic modelling to compliment experimental findings. The successful applicant will join a welcoming, vibrant group of 20+ researchers examining environmental radioactivity research topics and receive training in a wide range of experimental techniques and methodologies including the handling of radioactive materials and X-ray absorption spectroscopy. They will also have the opportunity to present their research results to their nuclear industry supervisor, and at national and international research conferences. The PhD project will form part of a wider research portfolio on phosphate based cements.

Institution: University of Manchester

Supervisor(s): Prof Katherine Morris, Dr Thomas Neill, Prof Sam Shaw

Sponsor(s): Nuclear Waste Services

Ventilation of Hydrogen in a Geological Disposal Facility

Title: Ventilation of Hydrogen in a Geological Disposal Facility

Description: The aim of this project is to predict the behaviour of slowly-released buoyant gasses in a Geological Disposal Facility (GDF) and inform the design of ventilation for such facilities. Geological disposal involves isolating radioactive waste in a vault deep inside suitable bedrock to ensure that no harmful quantities of radioactivity ever reach the surface environment. A GDF will be a highly engineered structure consisting of multiple barriers designed to provide protection over hundreds of thousands of years.

Hydrogen gas – which is potentially flammable – can arise from the corrosion and degradation of certain types of radioactive waste. Ventilation of hydrogen is a significant engineering challenge for a GDF; new research is required to inform the design of the vaults themselves and size the mechanical ventilation for them. Passive safety in the event of a loss of power is a further consideration.

The release of dense and buoyant gases has been extensively studied, including several recently by the project supervisor (Dr Andrew Lawrie) on determining scaling laws for particular geometries. Here our focus will be to migrate existing understanding of special cases into the more general GDF context to predict the likely evolution of hydrogen concentrations. The key scientific challenge lies in estimating the rate of molecular mixing in a vault environment that will have thermal sources and may become density-stratified.

Laboratory experiments measuring vault circulation and release concentrations directly (primarily using non-invasive optical methods) will provide validation for Computational Fluid Dynamics models that will inform the design of GDF vaults and ventilation structures. A sensitivity analysis of the flow will guide suitable locations for a network of hydrogen leak sensors designed to solve the inverse problem of leak source-finding amongst the many individual radioactive waste packages that will be stored in the vault.

Candidate Requirements: Applicants must hold/achieve a minimum of a Masters degree (or international equivalent) in one of the following: Aerospace Engineering, Physical Sciences, Mechanical Engineering, Chemical/Process Engineering. Applicants without a Masters qualification may be considered on an exceptional basis, provided they hold a first-class undergraduate degree.

Some experience in programming in a compiled language relevant to the design of numerically intensive simulation is essential.

Institution: The University of Bristol

Supervisor(s): Dr Andrew Lawrie

Sponsor(s): Radioactive Waste Management Ltd