The Impact of Spectral Shapes of Ground Motions on Seismic Probabilistic Risk Assessment of Nuclear Power Plants
Date Issued
2014
Date
2014
Author(s)
Chen, Hong-Ming
Abstract
Seismic probabilistic risk assessment (SPRA) has been widely used to compute the core damage frequency of a nuclear power plant (NPP). In this study, seismic risk of a sample NPP is computed using a SPRA methodology proposed by Huang, Whittaker and Luco in 2011. The methodology requires response-history analysis, which often involves the selection and scaling of ground motions for a target spectrum. The use of artificial ground acceleration time series spectrum-matched to a uniform hazard spectrum (UHS) does not consider the correlation in spectral accelerations at different periods and has been criticized to be significantly conservative for some purpose.
In this thesis, the impact of spectral shape of a target response spectrum on the result of SPRA was studied. The seismic risk was defined as the occurrence of a sample accident sequence for the sample NPP. Four sets of ground motions were developed for this purpose:
(a) CS Group. The target spectrum for this group was developed using the Conditional-Spectrum (CS) concept. The distribution of spectral acceleration at a given period for the ground motions in the CS Group fits both the median and dispersion required in the target CS.
(b) CMS_A Group and (c) CMS_B Group. The target spectra for the two groups were developed using the Conditional-Mean-Spectrum (CMS) concept and are the same in the horizontal directions and different in the vertical direction. Each ground motion in the two groups is artificial time series spectrum-matched to the target CMS. A prediction model for correlation coefficients for spectral accelerations at different periods was proposed for ground motions recorded in Taiwan and used to develop the target CMS used in this study.
(d) UHS Group. Each ground motion in this group artificial time series spectrum-matched to a target UHS.
The dispersion in spectral acceleration of ground motions for the CS Group has significant impact on the dispersions in the structural responses and the risk of the sample NPP. The seismic risk of the sample NPP for the CS Group is higher than that for the other groups.
Subjects
核能電廠
機率式耐震風險評估
非線性動力分析
條件平均反應譜
相關係數
Type
thesis
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