Conceptual design of DEMO breeding blanket in-vessel toroidal transporter

Abstract

The development of a viable maintenance strategy for the replacement of the Breeding Blanket (BB) segments of DEMO is a key aspect in the way for fusion energy. Previous work concerned the development of a BB vertical transporter to lift, tilt and handle the BB segment inside the remote handling (RH) ports. A potential solution for the replacement of the BB segments could consist in lifting all BB segments from four RH ports, by mean of BB vertical transporter coupled with a BB toroidal in-vessel transporter avoiding the opening of the remaining ports during maintenance. In this way, the activities concerning the removal and re-installation of the auxiliary components (BB feeding pipes, permanent structure for pipes handling, closure plate, port plug, etc.) inside the non-remote handling ports will be avoided, having a strong impact on the reduction of the remote maintenance times and hence on the overall availability of the machine. To assure the feasibility of the proposed strategy a dedicated tool, capable to move toroidally the huge BB segments, shall be developed. The main function of the tool will consist in lifting and toroidal translation of the BB segments that have to be aligned to the RH port, where they will be grabbed and lifted by the BB vertical transporter. The work here presented focuses on the conceptual design of a toroidal transporter to lift and toroidally translate the BB segments inside the Vacuum Vessel. The conceptual design of the BB Toroidal Transporter (BBTT) was developed to handle both the inboard and the outboard segments; a foldable lower foot, equipped with toroidal trucks and suspension system, has been designed to withstand the assumed loads and seismic loads. Preliminary FEM analysis has been carried out to check the structural integrity of the proposed design.