High level vibration test of nuclear power piping

A series of seismic capacity tests of nuclear power piping have been performed to investigate elastic-plastic response characteristics and obtain additional data concerning the ultimate limit of a piping system subjected to earthquake excitations. The test model was designed by modifying the 1/2.5 scale model of a PWR primary coolant loop. Elastic and inelastic seismic response behavior of the test model was measured in a number of test runs with an increasing excitation input level up to the limit of the vibration table. In the maximum input condition, large dynamic plastic strains were obtained in the piping. Crack initiation was detected following the second maximum excitation run