PhD Projects at Manchester

These projects are run by The University of Manchester. Application information can be found in our how to apply section.  Please contact the relevant person below before applying. Click on the titles below to see contact details and more information.

  • Long-term interactions of radionuclides with iron oxyhydroxides in geodisposal and contaminated land environments: A combined abiotic and biological study. 

     

    Contact: Dr Sam Shaw

    The UK has a substantial legacy of nuclear wastes and its safe management is a national priority. Understanding the long-term fate of radionuclides in the environment is key to developing safe management of radioactive wastes and radioactively contaminated land. In radioactive waste disposal, during evolution of the repository, iron oxyhydroxides will be present in wastes and will also form from the corrosion of steel canisters and engineering iron. Recent studies have indicated that iron oxyhydroxides can incorporate a range of radionuclides, including actinides [1-3] and Tc [4]. These sequestration processes have the potential to act as a secondary barrier to radionuclide migration in waste disposal. However, changes in the abiotic and biologically driven processes that occur over the long-term within the environment will alter the biogeochemistry within and around the repository. In turn, this will influence the stability of the iron oxyhydroxide minerals formed and ultimately these changes will impact on the speciation and fate of the radionuclides with the potential for re-release to occur. This experimental study will focus on characterising the fate of key risk driving radionuclides (i.e. U, Tc and Np) associated with deep geological disposal relevant iron oxyhydroxides (e.g. magnetite and goethite) during conditions relevant to the long-term biogeochemical evolution of a repository. The project will examine the influence of both abiotic and biological processes on radionuclide speciation and fate, and utilise advanced geochemical, nanoscale characterisation and microbiological genomic techniques to probe the mechanisms of radionuclide interactions.

     

    Iron (oxyhydr)oxides are ubiquitous in radioactively contaminated environments including contaminated land and radioactive waste disposal systems. In addition, they are sorbent materials utilised within the nuclear industry for clean-up of waste streams, for example in the Sellafield Enhanced Actinide Removal Plant (EARP). Within these contaminated environments, a variety of phases can form as colloids or coatings on mineral surfaces including Fe(III) (oxyhydr)oxides (e.g. goethite) within oxic environments and microbially-mediated formation of Fe(II)/Fe(III) phases (e.g. magnetite) under anoxic conditions. Iron oxyhydroxides are also predicted to form within geodisposal facilities e.g. via corrosion of steel from waste canisters / engineering forming Fe(II)/Fe(III) bearing phases including magnetite, green rust and siderite. The speciation and transport of long-lived radionuclides (e.g. U, Tc and Np) in these systems are often controlled by interaction with iron oxyhydroxide nanoparticles. In particular, surface induced reduction (e.g. forming U(IV)O2), incorporation into particles (e.g. U(V) stabilised in Fe(II)/Fe(III) phases [1] and U(VI) incorporating into hematite [1]) and biological reduction processes (e.g. forming UO2 or non crystalline U(IV) [6]) have been observed in geological disposal relevant systems. However, the biogeochemical conditions within these environmental and engineered systems will fluctuate with time including, for example, changes in oxygen levels, fluid composition and microbial nutrients / electron acceptors. These changes could alter the stability of iron oxyhydroxides phases through abiotic and biologically driven redox processes leading to transformation reactions or dissolution. In particular, both abiotic and microbially driven redox processes can facilitate the atom exchange of Fe within minerals, and electron transfer between the solution and solid mineral particles. These processes are dynamic and can lead to significant amounts (up to 100%) of Fe within the solid phase being exchanged with the solution over time scales 

  • Development of a photoionization mass spectrometer for 85Kr detection

    Contact: Dr Kieran Flanagan

    The radioactive isotope 85Kr is continuously produced in civil nuclear power plants and plutonium breeding. This has made it extremely useful for monitoring reprocessing activity and the release of plutonium into the environment. Monitoring stations have relied on large gas volume sampling (10 m3). This requires cryogenic collection and further purification of gas over the space of week before enough activity is available for proportional counters to measure. Technology has now reduced the collection time to a period of 1 day and this improvement in resolution permits much smaller releases of 85Kr to be identified above the background level. Ideally a table top device that can continuously sample the atmosphere constantly would be desirable.

    This project would utilize the collinear resonance ionization spectroscopy (CRIS) that has been developed at CERN to detect exotic short-lived isotopes produced at rates of less than 1 atom/second. The work at CERN has demonstrated that the CRIS method represents a factor of more than 100 enhancement in sensitivity, compared to ICP-MS, with the capability to reach below 1 part in 1016. When combined with a modern ECR ion source (capable of >50% ionization efficiency), it is possible to continuously sample the atmosphere and detect changes in the concentration of 85Kr within 10 minute time intervals. Such an enhancement in time resolution would significantly improve the current detection limit on the release of Pu from reprocessing plants. It would also provide a powerful tool for detecting unreported Pu production. 

  • 2-dimensional material sensors for extreme environments encountered in nuclear fission

    Contact: Dr Aravind Vijayaraghavan 

    Nuclear fission technology critically relies on continuously monitoring the process environment by measuring parameters such as pressure and temperature. 2D materials have shown great potential for sensing in harsh environments due to their exceptional strength, high temperature stability and immunity to ionising radiation. In this project, we will develop sensors based on graphene and other related 2-dimensional materials that would function under the extreme operating conditions that are faced in nuclear fission technology. Pressure sensors are used in a nuclear reactor in various locations - pumps, protection systems, reactor core, fluid levels. The sensors will be engineered based on the principles of nano-electro-mechanical devices, or NEMS.  The student will design, model, fabricate and test 2D material NEMS devices as well as construct new testing equipment to simulate the harsh environment of the nuclear fission process. The fabrication of devices will involve extensive use of the National Graphene Institute and its state-of-the art clean-room facilities. The project will also involve a close contact with Atomic Mechanics, a sensor business specialising in 2D material NEMS, who will support the student with testing capabilities and sensor integration know-how. The student will require experience in experimental research with a focus on electronic devices and sensors. A background in graphene and 2D materials is preferred but not essential. A student undertaking this PhD project will acquire expertise in various monitoring systems in nuclear reactors, how such systems are linked to the operation and safety of the reactor, and in constructing robust sensor systems to operate under the extremes of pressure, temperature and radiation that are characteristic of nuclear fission reactors.

       

  • Porous metal-organic frameworks as emerging sorbents for nuclear wastes

    Contact: Dr Sihai Yang 

     

    During the nuclear waste disposal process, radioactive iodine in fission products can be released, posing significant health risks to humans through the respiratory system via both beta and gamma radiation.The widespread implementation of nuclear energy thus requires the development of efficient iodine stores that have simultaneously high capacity, stability and, more importantly, storage density (and hence minimised system volume). This is, however, a very challenging task and requires integrated materials solution. Herein, we propose to develop new robust metal-organic framework (MOF) materials as multi-functional scrubbers of nuclear wastes, particularly for iodine. Understanding the mechanism by which these porous MOFs bind guest molecules at a molecular level is of critical importance in designing and optimising successive generations of new materials with better storage capacities and selectivity. The proposed PhD project will: (i) synthesise and characterise a series of new MOFs showing high porosity, robust framework structures and decorated pore environments; (ii) systematically test the adsorption of iodine by these MOFs under varying conditions (e.g., liquid phase, vapour, mixture, high pressure/temperature); (iii) investigate the active binding sites of iodine and host-guest binding dynamics in nanoporous space (0-5 nm) of the best-behaving MOFs via synchrotron X-ray and neutron scattering techniques; (iv) develop a “structure-function” relationship to guide the design and discover of new generation of MOFs showing improved adsorption of iodine. This project will be complementary to our ongoing research at Diamond, ISIS, ESRF, ORNL and ALS studying porous MOFs for gas capture using X-ray and neutron scattering.

  • Radiation effects in bespoke glass formulations

    Contact: Dr Laura Leay

     

    The decommissioning of Sellafield site represents many technological challenges, including dealing with the radioactive waste that is generated. Tanks that contained highly radioactive waste will be washed out and the resulting liquid will be incorporated into glass. Although Sellafield has been using this method of waste immobilisation for decades, the waste generated from cleaning out these tanks will have different properties to the waste they have dealt with in the past. A new type of glass formulation has been developed by the National nuclear Laboratory to immobilise this waste. To date this has used non-radioactive surrogates to determine a suitable glass composition; the performance of this material under a radiation field is not yet known. This will be the focus of this project.

     

    Changes in the structure of the glass can be characterised and atomistic simulations can be used to provide an in-depth understanding of glass behaviour, validated using the experimental results. The non-radioactive samples that have been produced include large crystal structures so special attention can be given to the interface between the crystalline and glassy regions. In addition, the interplay of the different elements within the glass can be determined by creating samples with fewer components. The effect of radiation on corrosion of the glass can also be investigated and this information will be vital to underpin the safety assessment of a geological disposal facility.

     

    ***This project is based at the Dalton Cumbrian Facility near Whitehaven in west Cumbria; it is not based in Manchester***

  • Laser Induced Breakdown Spectroscopy – Assessing use in the Nuclear Industry

    Contact: Dr Gareth Law

    ***Please note that the closing date for applcations in connection to this project is 7th Dec 2017***

    Given the dose and cost implications associated with working with radioactive samples, there is a need for rapid, standoff analytical techniques in the nuclear industry that permit analysis of contaminants (e.g., radionuclides, organic complexants) on material surfaces. This can then aid plant operation, material sorting / sentencing, and decontamination practices during decommissioning and plant post operational clean out (POCO). Laser Induced Breakdown Spectroscopy (LIBS) is a candidate technique that permits elemental analysis from unprepared surfaces, as long as there is a line of sight between the sample and the LIBS machine. Further, when used in multi-pulse mode, LIBS can permit analysis of contaminant penetration into materials and recent work at Manchester and NNL has highlighted that LIBS can provide speciation information for select elements. The technique is also meant to be non-destructive. However, there is much to learn about LIBS use in the nuclear industry and this forms the basis of this NNL sponsored PhD project.

    Specifically, the PhD will work towards better defining what radioactive and organic species LIBS can analyse on/in a range of materials important to the nuclear industry (primarily varying grades of steel and different types of cement and plastics). The studentship will also seek to define whether LIBS analysis adversely affects the material being analysed such that it cannot be re-used in the nuclear industry. This will be assessed through materials characterisation and contamination studies conducted after LIBS analysis.

    The studentship builds on recent collaborative work between UoM, NNL, and Sellafield Ltd. where we have demonstrated use of LIBS for Cs and Sr characterisation on austenitic stainless steel, select U compounds, and graphite [e.g. 1]. The successful student will be trained in LIBS analysis, microscopy techniques, surface characterisation techniques, radiochemistry techniques. Applications are encouraged from students expecting to receive a 1stor 2.i in a physical science discipline. The project will be based out of the University of Manchester School of Chemistry Centre for Radiochemistry Research (Law, Heath), and Dr Gareth Law will be the primary supervisor. The student will also have access to laboratories and techniques in the Manchester School of Materials (Engelberg) and the NNL / University of Manchester PHAROS laboratory (Smith, Trivedi)

    [1] Lang et al., (in press). Analysis of Contaminated Nuclear Plant Steel by Laser-Induced Breakdown Spectroscopy. Journal of Hazardous Materials. NOTE: A copy of the accepted paper can be provided by Law on request.

     

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