Analysis of Inspection Methods for Power Spectral Density in Seismic Qualification Test of Equipment in Nuclear Power Plants

In order to meet the power spectral density (PSD) requirements of the input motion in the seismic qualificaiton test of equipments for nuclear power plants, the inspection method of PSD is analyzed and evaluated in this paper, based on the study on the background of the standards and the target PSD algorithm and the comparative analysis of typical examples. The results show that the most intuitive method of PSD check is to compare the PSD for input motion with the target PSD. According to the accuracy and conservativeness of the results of different types of methods for developing target PSD, it is recommended to use the synthetic time-history method in Appendix B of U.S. NRC SRP 3.7.1(2014) to calculate the target PSD. Although this method is generally applicable to the site-specific response spectra of nuclear power plants, it is also applicable to the test response spectra (TRS) for seismic qualification by replacing the target response spectra with TRS in the process of the synthetic time history. When using the proposed method to calculate the target PSD, the PSD check for the seismic identification input motion should be consistent with SRP 3.7.1, which envelops 70% of the target PSD between 0.3Hz and the upper bound frequency of the target response spectra.