Abstract: Biomass is a generic term for a wide range of organic materials, including wood, which is used to generate electricity and/or heat. Waste wood is just one form of biomass for which there is rapidly growing interest in the UK. An overview is provided of the issues involved in the generation, processing and use of wood waste as biomass.

Abstract: The Parsons 500 and 660 MW single line steam turbines designed in 1962 and 1967 respectively were the first operational machines in their class in the UK and became the proving ground for the forms of construction used across the Parsons fleet over the following 40 years. The 500 MW units employed classical Parsons construction. The 660 MW units were the first machine type to be designed after Parsons took over the steam turbine generator business of GEC and were hybrid designs combining the technologies of both companies. The operating experience and lessons learned with these machines are described. Since the turbines achieved record UK efficiency levels for over 20 years, withstood both prolonged two-shifting and base load operation, have completed up to 300 000 running hours on lead units and with a further potential life of 15+ years ahead, the designs are considered to be a great success. Nevertheless, there have been some notable lessons learned along the way which are described.

Abstract: Overestimation of creep life is a serious problem that happens in long term creep of welded joints made of 9–12%Cr ferritic steels. Creep rupture data of welded joints made of grades 91, 92 and 122 steels were subjected to multiregion analyses paying attention to change in activation energy Q for creep rupture life. A region with a low Q value was found in long term creep of the welded joints. Therefore, long term creep rupture life of the welded joints can be overestimated when it is evaluated by temperature acceleration tests based on a high Q value of short term data. The decrease in activation energy was closely related to the change in fracture location from base metal to heat affected zone. Activation energy and stress exponent for creep rupture life take similar values both in base metal and in the welded joint, though the transition to the low Q region starts at shorter time in cross-welded joints. This fact suggests that creep rupture life can be formulated in a unified manner irrespectiv...

Abstract: An overview is given of the significant materials aging issues for nuclear power reactors. Despite the fact that many of these issues were not anticipated at the design stage, the development of active management techniques, backed by improved understanding and modelling of the underlying processes, has permitted many nuclear plants to run safely and efficiently well beyond their design lifetime. The mechanisms of aging are reviewed and management strategies for aging plant assessed. In conclusion, the requirements and options for future nuclear plant are considered.

Abstract: Residual stresses in a circumferentially butt welded steel pipe have been measured and numerically predicted. The pipe, containing the circumferential weld, has an outer diameter of 290 mm and a wall thickness of 55 mm, typical of components in power generation plants. An axisymmetric thermomechanical finite element (FE) simulation has been performed to obtain the residual stress field induced by the fusion welding of the pipe, taking solid state phase transformation effects into account and using temperature dependent material property data. Residual stresses have been measured using the X-ray diffraction and deep hole drilling techniques. Good correlation has been demonstrated with the predictions of the FE model. The paper demonstrates that a mixed experimental and numerical approach is useful for determining the residual stress distribution in welded joints.

Abstract: The thermal properties of paraffin/graphite composite phase change materials for power nickel metal hydride batteries were experimentally investigated. Two different modes for heat dissipation were designed in this experimental study: air cooling and cooling with phase change materials. Paraffin/graphite composite phase change thermal energy storage materials were prepared and tested by differential scanning calorimetry. It appeared that the battery thermal management system with phase change materials had better performance than air cooling, especially when the scale of paraffin/graphite composite material approximates 4:1.

Abstract: The dominant crack initiation and growth mechanisms for reheat steam pipes include creep and creep–fatigue, and the seam welds are particularly vulnerable. With historical data consisting of operating temperatures, pressures, average operating time between starts and stops, etc., and an extensive database of relevant material properties, an accurate model can be created that can be used to assess the risk of fracture in critical components and subsequent inspection strategies that mitigate the risks and lower them to acceptable levels. Physics based model predictions for material degradation combined with service experience based predictive approaches that constantly correct the model predictions using the experience base on specific machines can be used to create an approach that can produce highly reliable predictions. Such an approach requires the capability to solve inverse problems. This paper presents the capabilities of such a hybrid approach using reheat seam welded steam pipes as an examp...

Abstract: The effect of alloying elements on the mechanical properties and weldability of wrought gamma prime strengthened nickel based superalloys is well known. An understanding of the basic guidelines concerning alloying additions has led to the invention and development of HAYNES 282 alloy for applications in aircraft and land based gas turbines and other high performance high temperature environments. The alloy combines exceptional high temperature properties with good weldability and fabricability. At high temperatures (∼900°>C), the alloy is stronger in creep strength than Waspaloy alloy (UNS N07001) and it approaches the creep strength of R-41 alloy (UNS N07041). Because the alloy has better thermal stability, fabricability and weldability than Waspaloy and R-41 alloys, it is currently being considered as a candidate universal consumable for welding/repair welding of gamma prime strengthened nickel based superalloys and it is also being considered as a suitable replacement for applications where R-4...