Parametric fuzzy study for effects analysis of age on PWR containment cooling system

This paper presents an alternative parametric fuzzy study to subside aging impact analysis on the performance and availability of safety industrial systems. To this sense, a fuzzy fault tree computational system analysis, named of FuzzyFTA, was adopted. FuzzyFTA is a computing system that uses fault tree and fuzzy logic to determine fault event fuzzy importance and associated fuzzy uncertainty measures. The main goal of this approach makes possible, elapsed many years of plant operation, the gray determination of the system critical components and top event occurrence probability. A typical four loops pressurized water reactor (PWR) containment cooling system (CCS) was selected to examine the feasibility of the computational system approach in a real case study. Thus, a commonly found containment spray system and a fan cooler system were modeled. Failure rates, obtained from the operation of a PWR along 20 years, were accounted in the model. The bathtub curve characteristics presents in these failure rates permit the determination of the time-dependent effects of aging degradation more important to the general uncertainty of system. Thus, the system unavailability, considering the component failure rates increase by aging, can be calculated. (c) 2008 Elsevier B.V. All rights reserved.