MATERIAL LIFE EXTENSION

Material reduction, product life extension, material life extension, process improvements and product management are cill best achieved by consulting all relevant parties before the final architecture of a product has been settled. 

To enable these computational tools to be physically relevant, they will be integrated with experimental efforts focused on the provision of accurate physical descriptions of new materials systems to increase the fidelity of predictive models, and critical validation of predictions. The integrated set of computational tools will significantly reduce extensive testing schedules and inspection procedures, and will contribute not only to development and optimization of new and existing materials within acceptable costs and time frames but also to component life extension programs. 

It is also possible to carry out a probabilistic analysis for subsea pipelines in relation to the requirements of fitness for service or life extension. This approach is supported by Hopkins et al. (2001) where the uncertainty values in relation to the inspection data, material strength, and so forth are accounted for The statistics of the input parameters and the engineering models then determine, by probabilistic analysis, the failure probability for each failure mode or mechanism and the variation of the failure probability over time. Once the uncertainty of each input value has been described statistically, a Monte Carlo simulation can be used to predict the growth rate of known defects over time. 

C J Bolton, W Charnock and R H Priest, The effect of irradiation on fracture toughness transition temperature of Magnox reactor pressure vessel materials, Proceedings of the International Conference on Nuclear Power Plant Life Extension, Snowbird, UT, USA, July 1988. American Nuclear Society, IL, USA, pp. 197-203. 

Galea, S.C. and Rajic, N. Structural Health Monitoring and Life Extension of Military Aerostructures using Smart Materials. Proc. 15th Intemat. Conf. on Adaptive Structures (ICAST), Bar Harbour, Maine, USA (2004)... 

Silicon-based anode materials Several manufacturers claim progress in pure Si and Si-based composite areas (mostly, Si-caibons). The challenges ace mostly related to sceile-up of Si-based anodes, development of compatible electrolytes and cycle life extension... 

MCFC components are limited by several technical considerations (31), particularly those described in Section 6.1.1. Even though present approaches function properly in full size cells at atmospheric pressure, research is addressing alternate cathode materials and electrolytes, performance improvement, life extension beyond the commercialization goal of five years, and cost reduction (32). The studies described in recent literature provide updated information on promising development of the electrodes, the electrolyte matrix, and the capability of the cell to tolerate trace contaminants in the fuel supply. Descriptions of some of this work follow. 

The BWR pilot plant life extension study [6.31, 6.32] recommended that at least one jet pump inlet mixer subassembly should be disassembled, dye penetrant tested, and examined for erosion effects following 30 to 40 years of operation. The stainless steel material of the jet pump together with favorable inspection results to date indicates that... 

F. P. Ford, P. L. Andresen, M. G. Benz, and D. Weinstein, On-line BWR materials monitoring plant component lifetime prediction, Proceedings, Nuclear Power Plant Life Extension, Snowbird, Utah, American Nuclear Society, June 1988, Vol. 

J.R. Nicholls, Life Extension of alumina forming alloys - background, objectives and achievements of the BRITE/EURAM Programme LEAFA, in Lifetime Modelling of High Temperature Corrosion Processes, EFC Monograph No. 34, The Institute of Materials, London, 3-15 (2001). 

A more extensive comparison of many potential turbine blade materials is available (67). The refractory metals and a ceramic, sHicon nitride, provide a much higher value of 100 h stress—mpture life, normalised by density, than any of the cobalt- or nickel-base aHoys. Several intermetaHics and intermetaUic matrix composites, eg, aHoyed Nb Al and MoSi —SiC composites, also show very high creep resistance at 1100°C (68). Nevertheless, the superaHoys are expected to continue to dominate high temperature aHoy technology for some time. 

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