Modal and response spectrum analyses of an ITER divertor module

Abstract The present study is to investigate resistance of an ITER divertor module against typical seismic loads. Two kinds of complex finite element (FE) models, which consists of cassette body, inner and outer vertical targets, dome and stabilizers, were developed; one is 1- or 2-layer simplified models without consideration of inner tubes. The other is a 3-layer detailed model with the inner tubes as well as cooling water. Modal analyses to predict dynamic characteristics were conducted in use of block-Lanczos algorithm for all the FE models. Subsequently, response spectrum analyses were performed by employing three modal combination techniques and taking into account different seismic magnitudes. Analysis results from the detailed model led to higher von-Mises stresses than those obtained from the simplified model. Moreover, calculated stress intensities at critical locations were compared with corresponding design stress intensities, according to ITER structural design criteria for in-vessel components, which satisfied sufficiently the structural assessment requirement.