Nondeterministic method to analysis of the aging effects in PWR power plants components

This paper presents a contribution to the study of aging process of components in commercial plants of Pressurized Water Reactors (PWRs). The analysis is made through application of the Fault Trees Method, Monte Carlo Method and Fussell-Vesely Importance Measure. The approach of the study of aging in nuclear power plants, besides giving attention to the economic factors involved directly with the extent of their operational life, also provide significant data on security issues. In Brazil, for example, the Angra 1 Nuclear Power Plant invested $ 27 million to perform corrective actions in its network installation. This fact has generated an estimated operating life extension of Angra 1 in twenty years, offering great economy compared with building cost of a new plant and anterior decommissioning, if it had reached the time operating limit of forty years. The extension of the operating life of a nuclear power plant must be accompanied by a special attention to the components of the systems and their aging process. With the application of the methodology (aging analysis of the injection system of the containment spray) proposed in this paper, it can be seen the increase in the rate of component failure, due the aging process, generates the increase in the general unavailability of the system that containing these basic components. The final results obtained were as expected and may contribute to the maintenance policy, preventing premature aging process in Nuclear Plant Systems.