Thesis

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Browsing Thesis by Subject "Extraction"

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    New materials for selective separations at the back end of the nuclear fuel cycle
    (University of Sydney, 2016) Veliscek-Carolan, J
    Storage and recycling of nuclear waste are important issues that will increase in importance if nuclear power becomes more widely adopted worldwide. Recycling of used nuclear fuel is of benefit both in terms of increasing the nuclear lifetime (ie the number of years nuclear power will be a viable option for power generation) and decreasing the hazards (radiotoxicity, volume and longevity) of nuclear waste. Currently, most reprocessing of used nuclear fuel is performed using liquid-liquid extraction. However, use of solid sorbent materials has many advantages such the lack of organic solvent wastes. This research involves development of materials that are able to selectively remove specific target elements from solutions of used nuclear fuel. Once loaded with radionuclides, these materials may be utilised as transmutation matrices or wasteforms. Therefore, radiolytically and hydrolytically stable materials able to withstand the conditions of nuclear separations, such as titania and zirconia, have been targeted. Further, ordered porosity has been introduced into these titania and zirconia framework materials to improve their sorption capacity and kinetics. In order to impart selectivity to these materials, organic ligands are incorporated. Functional groups, including phosphonates, amines and peptides, have been chosen or designed based on their selectivity for elements relevant to the nuclear fuel cycle. Elements of interest include uranium, which constitutes >96% of used nuclear fuel and can be recycled; minor actinides, which contribute significantly to the radiotoxicity of nuclear waste and can also be recycled in fast neutron reactors; and lanthanides, which are targets for separation from the minor actinides as their high neutron absorption cross sections prevent transmutation of the minor actinides. Novel hybrid materials have been synthesized and their sorption characteristics, including selectivity, capacity and kinetics, evaluated. © 2016 The Author.