EFFECT OF SEISMIC ISOLATION ON THE TOKAMAK IN ITER

The support structure of the International Thermonuclear Experimental Reactor (ITER) is suggested to have appropriate stiffness that accommo dates both thermal distortion of the system and a maximum ground accel eration of 0.2 G (1 G = 9.8 m s(-1)) due to earthquakes. For a site wi th earthquakes more severe than 0.2 G; the seismic isolation design is a possible candidate for keeping the seismic input low enough. The pr esent design of ITER assumes that only the Tokamak pit portion is isol ated, due to the whole building being very large and complex. In this study, dynamic analyses of the whole Tokamak building with a base-isol ated Tokamak pit were carried out, and the effect of the isolation of the pit structure was evaluated. As a possible input level, a 0.4 G ma ximum ground acceleration was assumed. Particular attention was paid t o the relative displacement between isolated and non-isolated portions , due to the smaller relative displacement being desirable for the des ign of pipes across the isolation gap. (C) 1998 Published by Elsevier Science S.A. All rights reserved.