Experiences of Additive Manufacturing for Nuclear Fusion Applications: The Case of the Wishbone of the Divertor of DEMO Project

The aim of this work is to describe some experiences of additive manufacturing - AM - for nuclear fusion applications. In this paper, a first case study is introduced concerning the realization of a scale prototype of an in-vessel component for tokamak nuclear fusion reactors, a wishbone of the deflector made in Ti-6Al-4V alloy. The 3D model of the wishbone component was designed, optimized with simulation, and then fabricated using AM in collaboration with the Laboratory for Advanced Mechatronics - LAMA FVG - and researchers at the University of Udine. For the construction of the prototype, a SLM machine using powder bed metal laser melting was used. The design, simulation and fabrication activities of the AM mock-up are presented in this paper, discussing the main limitations and possibilities arising from the 3D printing of titanium alloy. In addition, a further scale prototype of the wishbone was produced using conventional milling techniques, allowing an economic comparison and evaluation of the two manufacturing processes. The prototypes will then be used for a future evaluation of the mechanical properties of this material (Ti-6Al-4V), first on material samples and then on the mock-ups, under irradiations conditions, due to nuclear fusion applications.