Vibration analysis in JT-60SU design

A dynamic analysis of the JT-60SU machine at emergency events such as an earthquake has been made. Superconducting coil systems and the vacuum vessel are modeled with beam and shell elements with a realistic weight distribution. It is found that a weight reduced design of TF coils, shear panel connection between two adjacent TF coils and favorable design of supporting system contribute to a higher eigenmode frequency for vibration. The fundamental eigenmode frequency of coil systems is 10.31 Hz and much higher than that of ITER. Dynamic response of the coil system using the acceleration (350–400 gal) of the floor of the machine room has indicated that the maximum displacement of the TF coil is within 2 mm and the acceleration of TF coil system is almost the same as that of the floor. A fundamental eigenmode frequency for the vibration of the vacuum vessel is 6.1 Hz and the maximum displacement is within 2.4 mm at the similar acceleration on the floor of the machine room. These results indicate sufficient robustness of JT-60SU system against an earthquake.