Preliminary Analysis of the Uncertainty Effect on Seismic Parameters and Frequency Spectrum for Nuclear Power Plants

The Regulatory Guide has been recently revised to take the very high frequency range, i.e., 50 Hz ~ 100 Hz into account for analyzing the structural damage caused by earthquakes. From this, it can be easily expected that the high frequency effect on various seismic parameters will be considered in seismic analyses of NPPs in the near future. It should be noted that the very high frequencies (>50 Hz) are currently filtered out and thus they aren't used to analyze the structural damage. Our preceding paper focused on the uncertainty effect on frequency response spectrum to investigate the error propagation in the very high frequency range (50~100 Hz) using artificially generated seismic data. In this work, the research continues to further investigate the uncertainty effect on various seismic parameters, such as Peak Ground Acceleration (PGA), Peak Ground Velocity (PGV), Arias intensity (Ia), Characteristic Intensity (Ic), Cumulative Absolute Velocity (CAV), and frequency spectrum to evaluate or predict the damage caused by earthquake for NPPs. Especially, in the analysis of the frequency spectrum, the uncertainty effect caused by measurement errors is focused and mainly discussed. To investigate the effect of measurement error (or uncertainty) on the five seismic parameters, the seismic parameters were calculated and compared each other using the adjusted measured data by employing the various offset error and gain error at each sampling point. The frequency response spectrum was also calculated by considering the randomly generated uncertainties. The numerical results calculated with offset error say that the seismic sensor may misgauge and cause misanalysed seismic parameters.