As seismic motion level for seismic resistant designing has been increased, usual tolerance is no longer enough in the existing domestic PWR and BWR plants.
In this study, the authors had an eye on devices supported by four legs in the existing domestic PWR and BWR plants, and established a reasonable earthquake-proof evaluating safety method compared to the original method (JEAG4601.that is earthquake resistant design code for nuclear plants in Japan).
This was done by establishing an analytical method which premises elasto-plastic deformation of the support legs that do not associated with device’s function maintenance.
At first, the support leg’s configuration of the devices supported by four legs in the existing plants was organized, and for the typical legs, the elasto-plastic behavior of support leg itself was verified by element test. Then the authors have established an analytical method that would simulate with result in element test.
Secondly, main configuration (including support leg configuration) of the practical device was organized, and for the typical devices the elasto-plastic behavior of the practical test object was verified by seismic excitation test. Then, the authors have established an analytical method that would simulate with result in seismic excitation test.
By implementing the established analytical method to a few practical devices supported by four legs in the existing domestic PWR and BWR plants, this analytical method was a reasonable method compared to the original standard.