DYNAMIC ANALYSIS OF THE TOKAMAK SUPPORT SYSTEM IN ITER

The ITER tokamak machine has a relatively flexible support structure a gainst horizontal loads as from an earthquake. Modal analyses and moda l transient analyses have been carried out by using the finite element analysis code NASTRAN to assess the response of the tokamak driven by a horizontal seismic load with the ITER design response spectra. Two types of three-dimensional models and a simplified mass/spring model h ave been used as structural models. The three-dimensional models have been used for modal analyses and modal transient analyses. The simplif ied mass/spring model has been used for parameter surveying of the tra nsient response. It has been shown in the analyses that the lowest nat ural frequency of the tokamak is about 2 cycles s(-1) and that the max imum relative response displacement between the magnet and the vacuum vessel is about 14 mm. (C) 1998 Published by Elsevier Science S.A. All rights reserved.