| Summary: | 碩士 === 國立臺灣大學 === 土木工程學研究所 === 95 === Storage of spent fuel is very important for the operation of nuclear power plant (NPP). In Taiwan, the space of water pools for temporary storage of spent fuel in the 1st NPP is running out, and the site of final storage facility is not decided yet. Therefore, the installation of dry type interim storage facility is imperative. In most dry storage facilities, storage casks are free-standing on the foundation pad, leading to concerns of their stability such as excessive sliding and overturning when subjected excitations. Consequently, this research focuses on the seismic response of the spent fuel dry storage facility.
For analyzing the seismic responses, two types of method are often used. One is to establish a cask-pad-soil coupled model by which the effect of soil-structure interaction (SSI) effect and the nonlinear contact behavior between the cask and pad are simulated at once. The other includes two steps. A simplified model for SSI analysis is established first to deduce the pad motions. Then it is used as the input motion for a pad-cask model in which the contact behavior on the interface is considered. The former assesses accurately the seismic response of dry storage facility, but the computational cost is expensive; the latter reduces the cost apparently, yet the results may be unsatisfactory.
In this study, the computer program ABAQUS is adopted to establish a coupled model and a decoupled model to analyze the seismic response of dry storage facility. Base on the results obtained, it can be found the decoupled model will have unreasonable high frequency acceleration and unconservative sliding and rocking motion. To overcome this difficulty, a modified decoupled model is proposed, in which the equivalent soil impedance is introduced in the pad-cask model. It can reduce the high frequency responses substantially. However, when using this approach, it should noted that the interaction between the SSI effect and the contact behavior on interface is still not taken into account.
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