Macro and Micro seismic analysis of TFTR structure

Because of the special configuration and operational loading of the tokamaks, their supporting structures assume common architectural shapes and structural systems. These shapes and systems prove to be susceptible to seismic motions causing the tokamac supporting structure to respond vigorously. Studies done by the writer indicate that the Umbrella Roof type of structures tend to possess natural frequencies that match the dominant frequencies of the typical seismic motions, giving rise to quasi-resonant conditions. Indeed, for the case of the TFTR, seismic loads became a factor in the design of the upper PF coils supports, the Umbrella Roof and the center and the peripheral columns. This is in spite of the fact that the Princeton site is considered a seismically weak one with a ZPA of 0.065 g for the most probable earthquake. If the tokamak type of reactors will be built on larger scales and/or on sites that could have moderate to strong seismic motions, there is little doubt that the seismic forces will be a major concern, probably governing the design of some key components and many connections. This paper addresses such possibilities in light of the analysis performed for the TFTR. This paper addresses two types of seismic analysis, Macro and Micro. By Macro is meant the global analysis of the structure incorporated with the surrounding buildings and soil. This type of analysis serves to produce response spectra curves and other important data that are used by various disciplines to seismically design their components. Micro analysis on the other hand deals with the members and components of the individual structures by which deformations, bending moments and stresses can be evaluated. The results reported herein are expected to serve the designs of the supporting structures of tokamaks to come