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No description available.

A significant proportion of the UK energy needs are currently serviced by a fleet of ageing nuclear reactors. Ensuring that these reactors are operated safely is the highest priority and the structural health of their cores, that provide channels for control rods and coolant gas, is a key aspect. This thesis focuses on the application of structuralhealth monitoring to the graphite reactor cores used in the UK and presents a specification for the use of structural health monitoring (SHM) techniques already es- tablished in bridge and aircraft monitoring, with data obtained through existing reactor monitoring processes. This approach utilises statistical and clustering techniques on monitoring data that can be acquired during online operation of the plant. The use of existing monitoring processes to complement the established inspection regime for nuclear reactors is a novel contribution from this work. As part of proving the SHM approach, this thesis reports on work undertaken to identify suitable data and numerical limits for the cluster analysis. This analysis considers the data with respect to the stated aim of detectin~ core distortion and demonstrates that the chosen data and values are acceptable and conservative in the context of reactor condition monitoring. An assessment of the SHM solution is presented describing the im- plementation of the SHM approach using a multi-agent system (MAS), IMAPS. This implementation required consideration of using MAS tech- nology for condition monitoring, and the novel contribution of a technique for storing and retrieving historical data in a manner concomitant with both MAS and relational database theory is presented.ij The thesis concludes that condition monitoring is feasible on the graphite cores, and that multi-variate analysis through SHM implemented within a MAS offers a storage and analysis platform that can both handle the data volumes and accommodate further extensions as required.

Atomic scale simulations have been carried out on three systems that are being considered for use in future nuclear energy applications, both fission and fusion based. Uranium dioxide and chromium doped fuel are considered in the early chapters in order to understand the processes important in high burnup nuclear fuel. The oxygen stoichiometry of the uranium dioxide lattice was found to have a large effect on both fission product solution and crystal swelling. Predictions were found to replicate experimental data well. Transport properties of cations via uranium vacancies in hyperstoichiometic UO2+x have been studied for the first time on the atomic scale. Understanding the arrangement of U5+ cations around a migrating species has proved important for identifying low energy migration process. Zirconium diboride and beryllium have also been studied. Zirconium diboride is of interest due to its use as a burnable poison for some advanced fuel types and also because of its ability to resist very high temperatures. The variation in stoichiometry of ZrB2 was found to accommodate excess boron but very little excess zirconium. The accommodation of the boron-10 transmutation products, lithium and helium, are also studied with helium being released from the lattice via a low energy process. Beryllium is of importance as a potential cladding for fission fuel and in fusion reactors. The intrinsic defect behaviour has been discussed for the first time in this thesis while extrinsic species present in beryllium alloys through alloying, manufacturing processes or environmental exposure have also been studied. Again, helium was found to be readily released from the lattice but only as an interstitial species and not as a substitutional defect.

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A conceptual model for the determination of the effect of specimen size on the strength of nuclear graphites was developed using abstraction techniques and finite element Analysis (FEA). The model was designed to be able to predict the response of nuclear graphites (primarily IM1-24 graphite) using fixed material properties under defined loading conditions and model constraints. Employing custom written C++ programs, randomly generated microstructural representations of IM1-24 graphite at a number of differing sizes were produced and subsequently had the stresses and strains through the model analysed using ANSYS FEA software. In conjunction with the conceptual modelling, a comprehensive testing programme was designed and developed to gain a data set for the validation of the model outputs. Two types of graphite were selected for the testing programme. Logically, IM1-24 graphite and a control graphite R4340. A large number of varying sizes of specimen were tested to failure under compression, 3-point and 4-point flexural loading and all results recorded and analysed. On completion of both programmes it was found that the modelling programme proved to be successful, in particular, the microstructural response of the virtual material when compared to the testing results. An issue of constant strain inherent in the models due to the loading conditions rendered the numerical results difficult to compare to the testing programme, but the data obtained for the testing programme has expanded the knowledge of the response of IM1-24 graphite at differing scales and loading conditions.

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No description available.

No description available.

This work offers a comparative economic study of the development and commercialisation of the LWR technology and an analysis of the thermoelectromechanical and nuclear equipment industry, with special reference to France, Germany and Italy. It takes the view that a nuclear power plant cannot be analysed as a technical good independent of the relevant technological environment and industrial structure. The chief contribution of the study lies in combining the analysis of a technology and the reasons underlying its selection and the grounds for success or failure of national technology paths, with investigation of the relation between the technology and structure and organisation of the industry. Major emphasis is laid on the evolutionary nature of nuclear technological change, and its incremental rather than radical innovation path, dictated by criteria of technological-industrial continuity. The study thus focuses on the interplay between technology, market structure and state intervention, and the effects of these factors on national nuclear systems and international trade. The work is divided into three separate but interrelated parts. The first is concerned with economic aspects of technological change and, in particular, the role, instruments and extent of state intervention in the industrial economy and technology policy. Part II is devoted to the development and co •• ercialisation of LWRs. The approach adopted combines historical and economic analysis. An account is provided of the early stages of growth of the US nuclear industry and its establishment on the world market. The growth paths of the main European industries are examined with emphasis on the transition from independent technologies, to US licensees, to the successful autonomous implementation of the LWR, and the problems encountered by further nuclear expansion. Rere - as in Part III which provides a more detailed analysis of the development and present situation of the Italian nuclear system - stress is laid on the institutional frameworks in promoting innovation and technical change, and in providing adequate export support.