Design modification of plasma facing component and cassette body for ITER divertor

The ITER divertor design, as originally conceived, required further optimisation to overcome the critical issue still remaining after the first assessment and to reduce the redundancies of some feature. In particular, the analyses carried out on the cassette body (CB) and the divertor plasma facing component (PFC) showed substantially high stress due both to thermal and fast-vertical displacement event (VDE) loads to be reduced by modifying the attachment system and making provisions for reducing the electromagnetic loads (EM). On the other hand, it has been demonstrated that a large margin exist in the shielding capability of the proposed design as well as in the required stiffness of the CB. The reduction of the CB thickness allow for a reduction of the thermal stresses. The design revision required many scope analyses to find the best configuration from the EM standpoint, neutronic analysis to assess the minimum shield thickness and a thermal-mechanical analysis on the modified attachment system. The results of the new set of analyses show the soundness of the modified divertor system.