Characteristics of Seismic Floor Motions

Abstract

<p>The overall objective of this study is to obtain characteristics of seismic floor motions in a nuclear reactor structure in order to examine current procedures used in seismic qualification of nuclear power plant equipment. The study incorporates seismic data from real earthquake events and uses these records as inputs to a mathematical model of a CANDU nuclear reactor building. Seismic floor responses at typical equipment locations are calculated by standard techniques of structural dynamic analysis. Six mathematical techniques are applied to develop characterizations of each seismic floor response record. From this data a set of parameters are evolved to qualitatively and quantitatively describe the characteristics of the ensemble of floor motions. Results of a theoretical study on sine beat, limited-duration sine, and decaying sinusoidal motions are compared to the characteristics of the seismic floor motions to evaluate the realism afforded by current single frequency seismic qualification test procedures. It is concluded that single frequency test motions have a valid application in seismic qualification test programs and can realistically simulate many seismic floor motion characteristics provided that the specific type of test motion and the test procedures are well defined. Recommendations are presented for the selection of single frequency test motions and for developing the test procedures.</p>