The impact of aging on life cycle cost: techniques for analysis and optimization

Systems, structures and components in a nuclear power plant are undergoing a variety of age-related degradation mechanisms (ARDMs) due to the severe environmental and operational conditions. Incorporating these recognizable, yet highly uncertain effects into a decision making or asset management process in a methodical way clearly requires a risk-based approach. This paper examines the impact of aging in the context of life cycle cost (LCC) analysis. Aging components generally experience higher failure rates which will have a direct influence on expected costs, and hence on overall system risk. The impact of aging can be modelled using the Weibull distribution, however, it must be modified in the context of life cycle cost analysis for consistent comparison of decision making alternatives. The results of this study demonstrate how age-based failure rates can have a significant influence on the net present value, and should therefore not be ignored, particularly for operational planning and asset management decisions related to end-of-life and refurbishment. The benefits of the developed methodology are demonstrated by integrating it with the life cycle planning of the main generator system. (author)