Development of seismic counter measures against cliff edges for enhancement of comprehensive safety of nuclear power plants, 8; Identification and assessment of cliff edges of NPP structural system

Nishida, Akemi  ; Choi, B.  ; Yamano, Hidemasa   ; Itoi, Tatsuya*; Takada, Tsuyoshi*  

In this research, the seismic safety of a nuclear power plant (NPP) is treated as a system in which the various cliff edge effects are identified and quantified based on the concepts of risk and defense in depth. An aim of this research is to develop a methodology for avoiding these cliff edge effects. In order to examine how the cliff edge state specified and evaluated in the seismic response analysis of the building system, we investigated the seismic isolation mechanism related to physical cliff edges and the modeling effects of the building system related to knowledge oriented cliff edges. In particular, with regard to knowledge-oriented cliff edges, we quantitatively evaluated the uncertainty within the same floor which is evaluated by a three-dimensional building model and tried to reflect it on the fragility evaluation. This paper presents and discusses these results.