Energy use, especially in the form of electricity is an essential requirement for modern life, and one that most of us could not even contemplate living without. From transport and travel to computers and televisions, the global demand for energy is on the increase. The drawback of recent technological advances however, is that greenhouse gases, in particular CO2 are emitted during the production of energy. Growing public awareness of climate change and its future impacts on the world as we know it have recently shifted the focus from fossil fuel usage to alternative energy sources, and legislation is now in place for reducing the carbon footprint. Among the alternative options, nuclear energy remains the most viable in the short term since the technology is already in place for proficient energy production. Nuclear electricity generation currently supplies around 17 % of the worldwide energy demand (18.4 % in the U.K.) and has already created a legacy of environmental problems due to high level radioactive wastes associated with waste storage and production. This proposal concentrates on the chemistry of the radioactive actinide ions (uranium, plutonium and neptunium) used in the nuclear fuel industry, ways to identify and 'clean up' toxic wastes from the environment and methods to eliminate the need for storing high level wastes in the future. Since the actinides used in current reactors are generated under conditions that are dissimilar to the natural environment, the chemistry of these metals outside of the reactor is completely different and they often exist in unusual oxidation states for a certain period of time before being further altered or reacting. In order to reduce the detrimental impact these radiotoxic wastes have on the environment, it is imperative that we understand their chemistry in full. This can only be achieved by studying the chemistry of these metals in their reactive unstable oxidation states in controlled laboratory conditions using specially designed chemistry. By doing this, we can identify methods of stabilizing these oxidation states and ways for selectively removing them from contaminated sites so that they can ultimately be recycled and used for further energy production. This project will initially examine the chemistry of uranium in the +V oxidation state by synthesizing a range of complexes stabilized by different organic groups under anaerobic conditions, and study the way the chemical groups around them inhibit or enhance reactivity. This chemistry will then be applied to the stabilization of the more radiotoxic elements plutonium and neptunium. At the core of the project is the development of a spectroscopic fingerprint (using time resolved luminescence spectroscopy) of unstable (and stable) oxidation states of these elements in order to develop a non-invasive method of identifying such species in the environment that may exist on a timescale that is too fast using current radiometric and chemical methods.

One of the most pressing problems facing society today is the management of existing and future waste forms arising from nuclear energy production. Here, the redox chemistry of the actinide elements plays a crucial role in many aspects of nuclear fission including safe disposal strategies and new recovery and recycling routes. Understanding the chemistry of actinides in engineered environments is imperative for the management of existing and future fission products (nuclear waste) arising from nuclear power production, particularly for underground geological disposal. In particular, the redox chemistry of neptunium, a key radionuclide found in appreciable quantities in high level waste is complex, changeable and currently not well understood. Over the lifespan of the proposed geological disposal facility, one of the principal hazards is a change in chemistry of neptunium that may result in leaching from the repository, breaching primary containment and entering the engineered environment. Due to the particular complex redox and chemical speciation of neptunium, crucial mechanistic information on redox chemistry and speciation that affects its interactions with engineered and natural encapsulating materials including the host rock and backfill material is lacking and remains one of the principal chemical challenges facing this field. In this feasibility study, we will address the prospect of using one and two photon fluorescence and phosphorescence spectroscopy and microscopy as a non-destructive technique to address this problem. We aim to visualise, locate and spatially map the different oxidation states of neptunyl that can co-exist in solution in model conditions using well defined complexes and aqua ions in with the ubiquitous geologically relevant minerals silica, alumina and calcite at previously unseen levels of detail (sub micrometer resolution). We have recently demonstrated that neptunyl(V) and (VI) emission occurs in the green and blue regions of the electromagnetic spectrum and are equally as intense as the uranyl(VI) ion, whose optical properties are well known and have been used by us for fluorescence and phosphorescence microscopy imaging. This means that both oxidation states can be detected simultaneously so that highly sensitive, informative three-dimensional imaging can be used to understand neptunyl geochemistry below the micron scale. This will add much needed important information to the safety case for nuclear waste disposal in a range of heterogeneous systems.

The safe decommissioning of facilities used in the nuclear fuel cycle (nuclear fuel reprocessing, research and development and energy production) is a major socio-economic challenge facing the UK, with a predicted total cost of £120bn over the next 120 years. The decommissioning process will generate large volumes of water-based waste (effluent) which is radioactive and must be treated. As well as a number of specific challenges associated with the current materials and processes used to treat effluent, many new challenges are likely arise in the near future as decommissioning activity gathers pace. Overcoming these challenges is critical in the context of establishing public confidence in the management of radioactive waste as well as underpinning the UK's long-term energy strategy. Graphene oxide, a derivative of graphene with a high oxygen content, has exceptional properties which have already been demonstrated in other fields (e.g. desalination), and may be able to overcome the limitations faced by the materials currently used in effluent treatment. Graphene oxide could be used to treat effluents in two separate ways. Firstly, graphene oxide flakes could be added to the effluent and used to directly bind radioactive species (adsorption). Alternatively, a semi-permeable membrane, fabricated from individual graphene oxide flakes, could be used to sieve out the radioactive species (filtration). In this innovative and ambitious project, the science underpinning the use of graphene oxide in nuclear effluent treatment will be developed using a methodology led by computer simulation. Firstly, the development of new 'coarse-grained' models of graphene oxide will significantly extend the length and time scales accessible to simulation and open up the possibility of investigating the stability of graphene oxide membranes and dispersions. Using the new models, the efficacy of graphene oxide for the treatment of effluents containing some of the most problematic and dangerous radioactive species (e.g. uranium, plutonium, caesium and strontium) will be assessed, delivering the relevant physical and thermodynamic data required for the next stage of process development. The design and performance of graphene oxide will be optimised to improve decontamination factors for specific effluent treatment challenges. As a result, the project has the potential to revolutionise the techniques used in the treatment of radioactive effluent.

This project aims to develop wireless technology to support the internal monitoring of industrial processes involving conducting liquids (e.g. water). Such processes are common in many sectors including the chemical, pharmaceutical and nuclear industries. The technology will be based on wireless sensor networks (WSN) which consist of collections of 'nodes' containing sensors, communications transceivers and an embedded computer system. Nodes organise themselves into a computer network, which is used to send sensor readings to a base station. The present proposal seeks to establish the UK as a centre of excellence for the development and application of this technology, and will significantly extend the work that we are currently carrying out in its application to grain processing.The project will research the technologies necessary to construct a network of small nodes that can be immersed within a process enclosure and which can sense local conditions and communicate readings through the network to a base station outside the vessel. An important and novel aspect of this work is the use of acoustic techniques, in a confined space, for communications and the determination of node position. The nodes will contain small scale buoyancy and propulsion systems enabling them to be manoeuvred to selected positions for measurement purposes. Software will also be developed to enable nodes to explore the process, a capability that is very important in a demonstrator system that will be developed with one of our industrial collaborators (Nexia).The use of a demonstrator system provides a focus to the generic research that will be carried out within the project. It is concerned with measuring the conditions within nuclear waste storage ponds, providing crucial information that will enable a carefully planned material removal and disposal programme to be carried out. This is clearly a timely application, given increasing public concern about the long-term storage of nuclear waste. However, the motivation for the research goes beyond a single application, and stems from the desire to overcome the limitations of current process measurement technology, and to provide much more accurate and detailed information about process dynamics than can be obtained at present. Access to such information will provide opportunities for increased plant agility, reduced raw materials uptake, reduced energy usage, reduced environmental impact, reduced waste generation and reduced occupational exposure via improved knowledge of the process.The key research challenges include the use of acoustic techniques within confined and potentially cluttered underwater environments, the development of very small scale buoyancy and propulsion systems, energy husbandry, and efficient exploration strategies. Clearly this requires a broad range of expertise. The team making the proposal includes three academic investigators from the University of Manchester, and one from the University of Oxford. The Manchester academics are from two research groups in the School of Electrical & Electronic Engineering: Microwave and Communication Systems and Sensing, Imaging and Signal Processing . They provide skills in communications (physical layers and protocols), embedded systems, sensing, and electronic systems. In addition, the lead investigator has experience in mechanical engineering. The investigator from Oxford is a member of the Software Engineering Group in the Computing Laboratory, and provides expertise in exploration algorithms and protocols. Four postdoctoral research assistants will be employed to support the work and to deliver the demonstrator. In addition two research students will explore the areas of mobility and power management, and exploration algorithms. Four support staff will contribute about three years of effort to the project.

Green rust is an iron oxyhydroxide mineral phase which forms in natural soils under reducing conditions. In addition, this mineral is an important product of iron metal corrosion in permeable zero-valent iron barriers, which are a novel remediation technology being used to decontaminate groundwaters of radionuclide, toxic metal and organic contaminants. Green rust generally consists of minute particles - nanoparticles - that have a very high surface area which gives them the ability to absorb a high concentration of species from solution. The formation of green rust can occur via both abiotic and biotic pathways forming a mineral structure containing both the reduced and oxidised forms of iron i.e. Fe(II) and Fe(III). The high surface area and presence of reduced iron within its structure make green rust an important reducing agent of both inorganic (e.g. uranium) and organic (e.g. tetrachloroethene) species within reducing and sub-oxic environments. This is particularly important for contaminant species which can be immobilised during such a reduction process (e.g. chromium). However, despite the hypothesised importance of green rust in natural and contaminated systems the contribution of green rusts to the biogeochemical cycle of iron has so far not been quantified. This is primarily due to the highly reactive nature of green rust, which means that the mineral breaks down within minutes when in contact with air. The characterisation of this phase has therefore been problematic using conventional analytical techniques. The aim of this project is to obtain quantitative data on the kinetics and mechanisms of GR formation and oxidative transformation using state-of-the-art in situ synchrotron-based techniques. In conjunction with this we will examine how the speciation i.e. oxidation state and nature of binding to the mineral, of trace elements (e.g. U and Cr) changes as the mineral particles growth and then transform during oxidation. By application of novel synchrotron based techniques we will be able for the first time to monitor these reactions in situ. This will provide high quality novel data on the reactions and also minimise the need to prepare the material for off-line analysis, which may cause oxidation artefacts to occur. During the project we will answer the following questions: 1. How does green rust nucleate and grow? 2. What controls the transformation of green rust to Fe3+-oxyhydroxides during oxidation? 3. What determines the speciation of trace elements associated with green rust as it forms and transforms during oxidation? 4. How do biogenic processes affect green rust formation and trace element speciation? 5. Under what environmental conditions does green rust form and how does this effect trace element and contaminant mobility in the environment? The first 4 objectives will consist of extensive experimental studies examining green rust under a variety of conditions analogous to those found in the natural environment. To answer question 5, the data from the experimental programme will be incorporated into geochemical computer modelling packages which will allow us to predict how green rust behaves in both natural system and contaminated land scenarios. For example, it will allow us to perform modelling under the conditions that green rust will form within a simulated nuclear waste repository so we can quantify the affect this phase will have on the mobility and bioavailability of uranium.