Search

This research has investigated the conditions necessary for atmospheric-induced stress corrosion cracking to occur in material taken from an intermediate level nuclear waste storage container by means of experiments in a humidity chamber. It has also characterised the residual stresses associated with the container welds by modelling and measurement. Based on the work conducted in this research, the major findings can be summarised as follows:• Deliquescence of salt particles is dependent on relative humidity but independent of the quantity of salt present.• The time to initiate cracking may be sensitive to temperature, getting longer as the temperature decreases, but the timeframe of work as not long enough to establish this conclusively.• AISCC can occur at a stress (residual or applied) of 400MPa (0.2% strain) or more if the other necessary conditions are present. While AISCC was not observed when no stress was present, the threshold of stress below which AISCC will definitely not occur has not been determined in this work.

In this thesis, current work carried out on analyzing the strategic behaviours in electricity trading is first reviewed. An intelligent decision-making and support technique, game theory, is often used in the market practice. Game theory is a discipline concerned with how individuals make decisions when they are partly aware of how their action might affect each other and when each individual might take this into account. Deficiencies and limitations of traditional game theory based methods developed for decision-making in electricity trading are also investigated. This research then explores to discover the impact of intelligent systems based trading strategies in the UK power markets. To model these behaviours and the New Electricity Trading Arrangements (NETA) system of the UK, traditional competitive and cooperative game theory strategies are taken into account in the work reported in this thesis. An improved methodology, “trigger price strategy”, is introduced to simulate power generation companies’ enhanced gaming strategies. Such modelling problem is, however, intractable and hence an extra-numerical search technique, Evolutionary Computation, is employed to solve the game theory based system modelling problem. An encoded Genetic Algorithm based technique is developed to search for an effective model for the complex decision-making process and to help decision-makers evaluate their strategies and bidding parameters. A novel and effective electricity trading simulation model is thus developed, where its design features are close to the NETA. The model scale is as close as possible to NETA. A complex and more realistic two-sided transaction mechanism with demand fully incorporated is incorporated in this model. These are a world first in this research area.