Forced vibration tests and analyses of nuclear power plants

Methods for conservatively predicting the response of a constructed nuclear power plant to earthquake excitations are presented. This approach is based on experimental testing of the reactor plant and using test results to develop a mathematical model of the system. First, steady state forced vibration tests are conducted using structural vibrators attached to the reactor structure to determine dynamic response characteristics. Second, modal analysis applied on a digital computer is used to create a linear multiple-degree-of-freedom model that has dynamic response characteristics nearly the same as the physical system for the experimental inputs. Finally, the input force levels are extrapolated from the levels of the inertial vibrators to earthquake levels and the response of the model is calculated for strong-motion earthquakes.Tests have been conducted on three nuclear power plants: the experimental gas-cooled reactor (EGCR) at Oak Ridge, Tennessee; the Carolinas-Virginia tube reactor (CVTR) at Parr, South Carolina; and the San Onofre Nuclear Generating Station (SONGS), San Onofre, California. Analyses in varying detail have been performed; the most extensive work has been done at San Onofre. This article summarizes test results, dynamic models, and the results of seismic response calculations for each plant.