This proposal presents a comprehensive approach for evaluating complex aging effects on systems performance and systems interaction. This approach consists of the combined application of an interactive modeling technique, the N-Square diagram, and systems engineering. The resulting methodology facilitates analysis of complex systems interaction. Emphasis is placed on evaluating the effects of component aging and service stress on functional and spatial systems interaction models representative of actual plant functions such as pressure and temperature control. The systems interaction methodology consists of development of several levels of N-Square diagrams to obtain a dynamic plant model. Consecutive levels of N-Square models are developed to reduce the system to the component level and then reduce the component to the lowest unit with aging significance (LUWAS). From here the effects of postulated and empircally generated age and service wear stress can be assessed, as potentially critical systems and component interactions are identified. The results of a comprehensive model of the systems and component interactions required to complete a plant function could be used to identify inspection, surveillance, and monitoring methods or corrective actions needed to assure plant performance.
Anticipated Results:As the existing plants age, environmental stress can combine to create unanticipated situations. Plant modifications and equipment replacements or substitutions have the potential to create unanticipated adverse systems interactions. A systems interaction model of the systems important to safety and operations provides an analytical and design tool to evaluate long term postulated conditions and determine the acceptability of necessary plant modifications and maintenance.
