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Modelling and measuring reactor core graphite properties and performance
No full textGas-cooled, graphite-moderated nuclear reactors suffer ageing and degradation to the graphite during service posing a threat to the functionality of the core, and potentially, the safe operation of the reactor. Thus, the importance of modelling and measuring reactor core graphite properties and performance increases especially as continued use beyond the designed life time becomes significant. This book captures the proceedings from the third in a series of meetings addressing the extensive research and analysis performed to ensure the continuing safe performance of the graphite cores. Covering four broad themes: mechanistic; statistical; empirical; and, plant performance, this book should appeal to a wide range of readers from engineers and reactor operators to policy makers
Should subjective risk be taken into account in the design process for graphite disposal?
No full textThe effect of reactor parameters on AGR refuelling at Hinkley Point B
No full textIt has been proposed that various reactor parameters, including temperature and pressure, could affect the measured load of fuel assemblies during refueling at the Hinkley Point B Advanced Gas Cooled Reactor. After processing station logs and matching the appropriate parameter values to a specific refueling event it was found that there is no detectable correlation between deviations in the measured load and the vessel pressure or the temperatures of various core regions. There is however a strong correlation however between the Dome Differential Pressure and deviation in the measured load relative to the absolute assembly weight, of up to 100kg
Intelligent graphite core condition monitoring
Get PDFCondition monitoring of graphite cores has increased significantly in recent years, as the safety cases required to continue operation of Advanced Gas Cooled Reactors (AGR) have evolved. This paper describes the development and implementation of intelligent systems designed to automate and formalise the CM analyses and tasks performed within the remit of the Monitoring Assessment Panels, which are currently being rolled out across the AGR fleet. The implementation of such systems is found to depend crucially on the involvement of station staff at each step of design and implementation, which is highlighted by the successful deployment of second iterations of the IMAPS system for managing reactor observations and the BETA system for automatically analysing refuelling data. Though each system was initially based on an individual analysis or tasks, this paper describes more recent work to allow closer integration of the systems as they are developed, in order to maximise the use of the available data while minimising duplication of effort and required operator time
BETA : a system for automated intelligent analysis of fuel grab load trace data for graphite core condition monitoring
No full textA key leg of the safety case required for operation of the Advanced Gas-cooled Reactor (AGR) stations is monitoring, particularly relating to the graphite core. It is not sufficient just to gather the monitoring data, but it must be analysed to extract the necessary information relating to the current condition of the core. The British Energy Trace Analysis (BETA) system has been developed to provide automated intelligent support to the analysis of Fuel Grab Load Trace (FGLT) data. FGLT data is routinely gathered during reactor core refuelling and can provide some information relating to the condition of the reactor core in addition to the inspections carried out during planned reactor outages. The process of developing the BETA software from a research prototype into a support tool which is installed on the British Energy network and accessible from anywhere in the company is described. The particular issues which have been addressed include the design, implementation, verification and validation of the software in terms of the core functionality, but also in the knowledge it contains in order to undertake its automated assessment of new refuelling event data. The second version of BETA is also described, highlighting the move to a web-based system with all the information relating to FGLT stored in a single location and describing the enhanced analysis that the BETA software undertakes. Finally, a forward look to the next version of BETA is provided, one which will integrate with other sources of condition monitoring data, and one which will have the ability to learn automatically as it is presented with new data
A Novel Approach for Evaluating Surface Deposits on the Channel Wall Trepanned Graphite Samples
No full textSamples have been trepanned from the fuel and interstitial channel walls of PGA graphite reactor cores of two operating Magnox gas cooled power stations after a period of service. These samples have been considered explicitly for the presence of deposits on the channel facing surfaces. A combination of focused ion beam milling and imaging has been used to determine the presence of such deposits and where present to make measurements of the thickness. These thicknesses vary from a few nanometres to tens of micrometres. In addition, both the chemical composition and chemical state have been investigated using energy dispersive X-ray microanalysis in a scanning electron microscope and Raman spectroscopy respectively. The results are discussed by comparing the microstructure, composition, chemical state and origins of the deposits with the parent graphite
Issues of scale in nuclear graphite components
Get PDFA 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
Optimisation of manufacturing systems for plastic moulded products in the automotive industry
Get PDFThis thesis presents a study of process planning instabilities and inefficiencies within a plastic component manufacturing company. The company was increasingly pressurised by high customer expectations and competition from the global market. A series of tools were used to highlight some of the prominent issues within the organisation. To improve on production efficiencies several lean manufacturing tools such as Value Stream Maps, Production Flow Analysis and Systems Thinking were applied. This thesis proposes a methodology for processing product lines within a supplier in the off-highway and niche vehicle industry and focuses upon categorising product lines depending upon their ranking of volume and value. The methodology presents a logical procedure for categorising parts into five "broad categories" analogous to the classical ABC stock control theory. On completion of the categorisation process, product lines are processed by a set of practical rules within the context of an "expert system". These rules have been devised by using multi-criteria ABC analysis and further applied to process the product lines throughout the manufacturing system. These rules are based on product line activity and they are defined in order to maintain minimum inventory levels as well as ensure the stable implementation of the factory production plan (smoothed over the production period), to also achieve a low throughput time and increase delivery performance, all with the goal of 100% on-time delivery to the customer. The analysis of sales data and high volume-to-value product lines has shown that there are five classes of product lines (A1, A2, A3, B1 and B2) which vary in their requirements for planning and operations as outlined in this paper. Evidence is presented which shows that an empirical relationship results a new "merit" parameter that can be determined by fitting a response surface to volume and value quantities and this relationship holds for a wide range of organisations. Indeed the technique can indicate which product lines are behaving in the market as expected and which are asynchronous with the market demand. The methodology was further simulated using Arena (R) software. The simulation study compared the models (before and after methodology implementation) and the results were analysed to assess the impact of the methodology on the production system
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