Improving the Performance of Advanced Technology Fuels

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The drive for change in nuclear fuel design is towards accident tolerance, which specifically relates to the absence or delay of high-temperature clad oxidation by coolant. Any replacement for UO2 fuel must offer a combination of safer operation with lower fuel cycle cost; either longer cycles or lower enrichment. The candidate material that offers the greatest combination of these properties with the potential for industrial scale-up is currently uranium mononitride, UN. However, there is a major behavioural draw-back in that water, and more importantly during operation, high T water/steam, is significantly more corrosive to UN than the UO2 oxide fuel currently employed in water moderated reactors.The proposed PhD project will specifically address the two key issues that are driving research of accident tolerant fuels (ATF): thermal conductivity degradation and corrosion behaviour, with the main focus on the fuel-water interaction. This interaction will be explored with relation to three key stages of the fuel life cycle, in operando (high temperature water/steam), in interim storage and in long-term waste storage scenarios. The project will require synthesis of both bulk and thin film samples; polycrystalline and single crystals, using UHV gas rigs and a dedicated actinide dc magnetron sputter system. Characterisation will be conducted using a range of surface analysis techniques, with particular emphasis on utilising x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS). We will make use of the Bristol Oxford Nuclear Research Centre (NRC) and employ the Oxford TEM suite to investigate the fuel surfaces on an atomic scale.The PhD is at the forefront of current UK research and development in nuclear fission. It will investigate potential avenues for improving fuel-water performance, including dopants and surface coatings, providing a comprehensive review of possible options