Structural and fracture mechanics analysis of ITER toroidal field coil

One of structural issues of toroidal field (TF) coil of a tokamak fusion device is a considerably large displacement due to out-of-plane electromagnetic loads induced by the interaction of TF coil current with magnetic fields. The displacement distributions and the structural integrity of TF coils are examined from the viewpoints of structural mechanics and fracture mechanics. The ITER TF coils without shear panels are investigated by Finite Element Method (FEM). Although the structural integrity is confirmed, there are large transverse displacements in the upper curved part of the TF coil. The effects of the TF coil displacements on the magnetic field distribution may be significant. Therefore, shear panels should be installed in order to reduce the transverse displacements. Assuming an initial crack in the maximum stress region of the TF coil case, the fatigue crack growth due to pulse operation is investigated. The stress intensity factor, K, is used in order to estimate the crack growth. The fracture mechanics analysis predicts no significant crack growth in the anticipated cycle of pulses in ITER