SEISMIC EVALUATION OF COUPLING EFFECTS BETWEEN PRIMARY AND SECONDARY SYSTEM BY USING MODIFIED BNL BENCHMARK MODEL

摘要

Base isolation is considered as a seismic protective system in the design of next generation Nuclear Power Plants. Nuclear structures, secondary systems and components must remain undamaged during and after the Safe Shutdown Earthquake(SSE) event. The seismic events will cause the high seismic response in the stiff structural systems and extremely high demands on the safety-related secondary systems like piping components. Seismic isolation of primary systems like containment building substantially mitigates these high demands on its own components and also secondary system components such as main piping systems by reducing the natural frequency of the Nuclear Power Plants. Many studies have been conducted on the base isolation as a seismic protective measure to structures. Most previous studies showed significant reductions in the seismic response of secondary systems through the use of properly designed seismic isolation systems [Huang et al. (2010)]. This paper presents the inelastic analysis results of coupled and uncoupled system that the piping systems connected to the base isolated primary structure with a conventional isolation bearing. Inelastic seismic response evaluation is performed for seismic fragility analysis of NPP piping system.