AUTOMATION AND OPTIMIZATION SEARCHES IN THE SEISMIC DESIGN OF THE PIPELINES SUPPORT SYSTEM (PSS)

摘要

Pipeline design of any NPP needs significant efforts due to the complexity of the systems and their scope. The NPP safety depends directly on the reliable work of the main pipelines of operating and safety systems. Generally the pipeline support system (PSS) allows controlling the behavior of pipeline after determination of its configuration and sizes for pipe section. The most pipelines perform heat-transfer function and have the thermal expansion. Therefore, they need to be released to avoid excessive stresses due to the expansion between constraints. The desire to build NPPs on various sites yields to necessity to increase seismic resistance of the structures and components. It may be done generally by means of additional constraints. So, there is the clear contradiction between the solutions for PSS in operating mode and during the seismic events. The conventional design process of PSS is manual and, as the result, dramatically time-consuming. There are two possibilities to approve such a design process. They can be combined with each other. First one is using expensive special anti-seismic devices - snubbers and dampers which need periodical inspections, testing and service. Second one is to dedicate the automation into the design process. This paper presents the second approach. The efficiency of the automation has been proved by the numerous examples during two years. The two different methods have been used to determine the useful locations for supports installation: automatic enumeration of possibilities and automatic optimization search to get an optimal solution in terms of stress safety factor. First method allows getting the initial PSS configuration. Second method tunes the existing PSS to get the best results in terms of operating capacity and seismic resistance. The last method performs the mathematical optimization theory and can use the coupled criterion for operating and seismic capacity. The manual design method becomes more efficient being combined with automatic optimization tuning. Current investigation concerns the automatic optimal selection of stiffness and damping properties for the pipeline supports. It allows stiffness and damping components of supports to arise and to disappear on relevant cases and to adapt their characteristic values for their maximal efficiency. The special springs and dampers can be implemented on the base of such method to get the maximal operational and seismic safety.