Electromagnetic analysis of electrical connections for ITER blanket module attachment

Each blanket module of International Thermonuclear Experimental Reactor (ITER) will be electrically connected to the vacuum vessel (VV) through two electrical straps. The electrical straps will carry the eddy currents and halo currents from the blanket to the vessel minimising the current affecting the hydraulic connection. 3-D electromagnetic FEM models have been implemented to analyse the electromagnetic transients during the different phases of a disruption. The analysed transients include: eddy currents induced by a variation of all the magnetic field components, during both the thermal and the current quench phases and halo currents flowing from the plasma to the vessel during vertical displacement events (VDEs). The electromagnetic transients have been simulated by means of appropriate boundary conditions and harmonic analyses, at frequencies related to the time constant of each electromagnetic transient, have been carried out instead of transient analyses. The electrodynamic pressure, the resulting global forces and torques on the critical components of the electrical straps and on the branch pipes of hydraulic connection have been evaluated. As a result, it was assessed that the electrical straps convey more than 99% of the total current flowing from the blanket to the vessel. The maximum current in the electrical straps is always within the halo current value, which was used to design the component. The EM forces on the hydraulic pipes are acceptable.