Organic ion exchange resins are utilised in many different areas of the civil nuclear fuel cycle, from uranium ore concentration and refinement and chemical control of coolant water composition in light water reactors and spent fuel storage ponds, to decontamination of radioactive element-containing effluents arising from fuel reprocessing and nuclear decommissioning operations. These materials are effective "sponges" for a wide range of radioactive elements, hence their widespread use. The UK has stockpiled approximately 600 m3 of spent (i.e., used) ion exchange resins (SIERs), which require disposal, and continues to produce between 2.5 to 13 m3 per year. The disposal of SIERs is problematic; there are several key issues, which include: 1. The 14C inventory of the materials. This isotope has a half life of 5,730 years and is incorporated as 14CO32- and H14CO3-, which, if allowed to enter the environment are extremely mobile and biologically available. Release of 14C gas in a disposal environment provides a rapid 14C migration pathway to the biosphere; 2. The degradation of SIERs in a disposal environment through radioactive decay processes produces organic complexant molecules, which may facilitate rapid transport of radioactive elements from SIERs to the biosphere; 3. The degradation of SIERs in a storage environment may also yield chemically toxic gases such as benzene, phenol and ammonia, which make storage extremely problematic. These issues require the SIERs to be treated so as to meet waste acceptance criteria for disposal. This is typically achieved by destruction using thermal or chemical processes. In this proposal, we aim to develop a promising chemical treatment route for the destruction of SIERs, known as wet oxidation. Wet oxidation has been successfully trialled elsewhere for the destruction of non-radioactive surrogates for SIERs, however, the specific methods previously utilised do not give rise to by-product residues that are amenable to immobilisation in a material suitable for disposal in the UK. We propose two novel approaches to wet oxidation processes that will not only generate by-products more suitable for immobilisation, but that also have a greater destruction efficiency than those previously trialled. Furthermore, we will develop and optimise tailored cement, ceramic and glass waste forms for the immobilisation of SIER degradation. We will provide a robust scientific underpinning of the chemical speciation and local distribution of radionuclides in SIERs and the immobilisation matrices we develop, and understand their behaviour in disposal environments, to support the safe and timely disposal of SIER wastes. A significant novelty of this research is the verification of our new treatment and immobilisation methods for SIERs using real radioactive materials. After optimisation of the processes described above using inactive SIERs, we will apply them to real radioactive SIER from the UK decommissioning programme. If successful, this work will be a significant step towards demonstrating an effective treatment option for the resin, allowing early site termination of a significant hazard.

Understanding the long-term durability of nuclear waste glass in the subsurface is important in the UK and internationally as many countries intend to dispose of vitrified radioactive waste in underground geological disposal facilities. In order to ensure safe disposal, we need to be confident that radioactive elements will remain isolated and immobilised for sufficient time to allow radioactivity to decay to safe levels. There will be multiple barriers in place (e.g. a metal container and engineered backfill) to delay groundwater from reaching the nuclear waste glass but eventually contact with water is expected. Although there are a number of laboratory tests currently used to determine the rate of glass dissolution in water all accelerate corrosion by increasing the temperature, surface area, or both and give very different predictions depending on the test conditions. Laboratory tests are also performed under simplified, stable, sterile conditions and using deionised water taking no account of how changing geochemical conditions will affect glass corrosion rates. This fellowship will combine materials science, geochemistry and geomicrobiology to study how glass corrodes in real-time in dynamic complex natural environments. I will improve understanding of key factors affecting corrosion (temperature, groundwater geochemistry, saturation, and microbiology) using the Ballidon long duration experiment, where glass samples have been buried for nearly 50 years. To predict the durability of nuclear waste glass thousands of years into the future I will study simulant nuclear waste glass's in conditions relevant to UK and US disposal concepts. The result of this novel investigation will be to critically evaluate, and improve, upon durability tests for glass, to build an improved model of glass corrosion and to establish further long duration experiments to inform the safety case for geological disposal in the UK and abroad.

As a result of 60 years of using nuclear energy in civil and defence operations, the UK has generated a large legacy of nuclear waste, with a total volume capable of filling Wembley Stadium (450,000m3). The hazards posed to the general public from the radiation arising from this waste make its disposal extremely challenging; any solution must be long-lived as the waste will be radioactive for more than 100,000 years. For this reason, the Governments of several countries, including the UK, propose that the long-term disposal of this waste should be in a deep geological facility, several hundreds of metres below the ground. The formal term for an engineered geological disposal site is a Geological Disposal Facility (GDF). This man-made facility will be used to isolate the waste from future populations by using multiple layers of containment carefully designed to prevent radioactive elements (radionuclides) from entering the underground rock environment and eventually reaching the surface. Arguably, the most important part of the GDF is the nuclear waste itself; the release of radionuclides to the environment is controlled by the interaction of groundwater with the waste - if this material can be shown to be particularly durable in the presence of ground water, the release of radionuclides will be very small and the risk to future populations from the GDF will be low. The focus of my Fellowship is on understanding the release of radionuclides from one particular type of nuclear waste, known as spent fuel, upon contact with groundwater. Many countries are planning to dispose of spent fuel in a GDF (e.g. Sweden, Finland), however the spent fuel in the UK is unique, because it originates from nuclear reactors that only exist in the UK. This is problematic because the potential behaviour of this material when it comes into contact with groundwater is poorly understood; this gives rise to uncertainty in the long-term safety of this material in a GDF. Therefore, the goal of this Fellowship is to develop an understanding of UK spent fuel, of how its structure and chemistry affect the release of radionuclides upon contact with water, and to evaluate its performance compared to other spent fuel types. Because real spent fuel is extremely hazardous, the Fellowship research team will develop an analogue for spent fuel, known as HIP-SIMFUEL, using state-of-the-art material processing technologies. The development of HIP-SIMFUEL, which will resemble spent fuel more closely than any other analogue currently available, represents a significant advancement for scientists working in the field of spent fuel research. Using HIP-SIMFUEL and a suite of advanced, high-resolution microscopy techniques, we will build the first ever atomic-scale understanding of the structure and chemistry of UK spent fuel, and we will develop novel imaging techniques to assess the role of these features in the mechanisms and rate of radionuclide release to groundwater. The results from experiments with HIP-SIMFUEL will be compared with those from real spent fuel particles; my team will examine particles of spent fuel that were discharged to the environment during the Chernobyl accident, which have subsequently been leached by natural groundwater for many years. My Fellowship is particularly timely, given the UK Government's ongoing task of selecting a site for the disposal facility. The research represents a significant step in the understanding of the long-term performance of nuclear waste in the GDF, will enhance predictive models of future GDF behaviour and will help optimise the design of the containment system. Ultimately, this will lead to enhanced safety of the long-term management of nuclear waste in the UK and worldwide, and will increase public confidence of geological disposal concepts.

UK government is committed to nuclear energy having an important role in delivering a secure, low-carbon and affordable energy future, with their aspirations for new build power stations and life extension of the existing fleet described in policy documents. Successful delivery of this policy recognises the need for research and development, skills development and international collaboration as key enablers. A central component is the need to demonstrate our ability to safely manage and dispose of civil nuclear waste. The Nuclear Decommissioning Authority is responsible for the delivery of policy aims with respect to legacy waste, with Radioactive Waste Management charged with the delivery of a geological disposal facility and waste management solutions. EPSRC strategy is to maintain investment in nuclear fission research, recognising nuclear power as having an important role in the future low-carbon energy mix, with a strategic focus being research underpinning the decommissioning, immobilisation and management of nuclear waste. Central components of all these strategies are "a joined-up approach to nuclear R&D across government, industry and academia which...benefit(s) the UK economy" and, of benefit to UK industry, that establishes it "as a global leader in waste management and decommissioning" (see Case for Support). The successful delivery of decommissioning, immobilisation and management of nuclear waste solutions also impacts on public acceptance of any new build programme. In relation to any geological disposal facility, there is a need to demonstrate an ability to safely manage and dispose of waste from legacy operations, with studies of public attitudes showing that acceptance of such a facility is directly linked to having viable routes for the safe clean-up and disposal of any waste. These strategies rely on further research and development being delivered over the next 10-20 years. The work of the consortium is part of the response to this need, providing support to an internationally leading group of researchers in this key area. The work will contribute to the health of nuclear fission research, and through developments within specific disciplines, to areas beyond nuclear. It addresses key societal challenges in relation to productive and resilient nation outcomes through the development of next generation technologies and by ensuring effective and affordable solutions for waste treatment. It will also contribute to the building of public confidence in waste management solutions, and assist the acceptance of nuclear power, as well as contributing to UK economic success by maintaining our position as a world leader in waste management research, and in assisting industry to maintain its world leading position. The consortium comprises key industry partners and leading academic researchers from 11 research intensive universities with significant expertise in nuclear research and development. The research proposed is multi-disciplinary and covers fundamental and applied topics, including 40 research projects clustered into 4 technical themes. The consortium is made up of established researchers from a diverse range of backgrounds, who are all leaders in their field, with a track-record of innovation and problem solving in the nuclear area. It also comprises many early career researchers who, as well as having relevant nuclear-related expertise, are included to provide them with invaluable experience of a large consortium project, and to further develop their profile and influence, as they mature into leaders in the field. The consortium builds upon and consolidates the work of the previous EPSRC-funded project DISTINCTIVE (Decommissioning, Immobilisation and Storage Solutions for Nuclear Waste Inventories, EP/L014041/1), bringing together researchers from a larger group of universities and increasing the multi-disciplinary nature of the group to extend and develop the academic skills base within the UK.

The EPSRC Centre for Doctoral Training (CDT) in Nuclear Energy Futures aims to train a new generation of international leaders, at PhD level, in nuclear energy technology. It is made up of Imperial College London (lead), Bristol University, Cambridge University, Open University and Bangor University. These institutions are some of the UK's leading institutions for research and teaching in nuclear power. The CDTs key focus is around nuclear fission i.e. that is the method of producing energy by splitting the atom, which currently accounts for 11% of the world's electricity and 20% of the UK's electricity, whilst producing very low levels of carbon emissions (at levels the same as renewable energy, such as wind). The CDT whilst focused on fission energy technologies will also have PhD projects related to fusion nuclear energy and projects needed or related to nuclear energy such as seismic studies, robotics, data analytics, environmental studies, policy and law. The CDT's major focus is related to the New Nuclear Build activities at Hinkley Point, Somerset and the Anglesey site in north Wales, where EDF Energy and Horizon, respectively, are building new fission power plants that will produce around 3.2 and 2.7 GWe of nuclear power (about 13% of the UK current electricity demand). The CDT will provide the skills needed for research related to these plants and potential future industry leaders, for nuclear decommissioning of current plants (due to come off-line in the next decade) and to lead the UK in new and innovative technologies for nuclear waste disposal and new reactor technologies such as small modular reactors (SMRs). The need for new talented PhD level people is very high as many of the UK's current technical experts were recruited in the 1970s and 80s and many are near retirement and skills sector studies have shown many more are needed for the new build projects. The CDT will champion teaching innovation and will produce a series of bespoke courses that can be delivered via on-line media by the very best experts in the field from across the CDT covering areas such as the nuclear fuel cycle; waste and decommissioning; small modular reactors; policy, economics and regulation; thermal hydraulics and reactor physics as well as leading on responsible research and innovation in the sector. The CDT is supported by a wide range of nuclear companies and stakeholders. These include those involved in the new build process in the UK such as EDF Energy, Hitachi-GE, Horizon and Rolls-Royce, the latter of which are developing a UK advanced modular reactor design. International nuclear stakeholders from countries such as the USA, UAE, Australia and France will support the student development and the CDT programme. The students in the CDT will cover a very broad training in all aspects of nuclear power and importantly for this sector will engage in both media training activities and public outreach to make nuclear power more open to the public, government and scientists and engineers outside of the discipline.