Construction and inspection of the vacuum chamber in the neutral beam injector for the MITICA experiment (ITER project)|Costruzione e ispeziani della camera da vuoto dell’iniettore di neutri per l’esperimento MITICA (progetto ITER)

MITICA (Megavolt ITER Injector & Concept Advancement) is the full-scale prototype of the reactor’s neutral beam injector, for the fusion plasma auxiliary heating in the ITER project, under construction at Cadarache, France, and aimed at verifying the technical feasibility of controlled thermonuclear fusion as a source of power. The ITER objectives can be achieved thanks to the indispensable contribution of the neutral beam of two of these injectors, each of which transfers a power of 16.7 MW to the plasma for pulses lasting up to one hour. The MITICA experiment, under construction at the PRIMA facility (Padova Research on ITER Megavolt Accelerator) managed by the RFX Consortium of Padua, aims to test and optimize the prototype of the ITER neutral beam injector. The MITICA components will be installed in a vacuum chamber consisting of two 304L steel modules joined by a flanged joint: the Beam Source Vessel (cube-shaped with a side of approximately 5 m and mass 67 t) containing the ion source and the Beam Line Vessel (with a section of about 4.5 m × 4.5 m, length 11 m and mass 76 t) containing the components along the beam line. Both vacuum vessels have been manufactured and tested by De Pretto Industrie of Schio, Vicenza. This paper aims to highlight the project implementation in design and fabrication requirements of these large vacuum chambers produced by welding and machining; topics such as materials selection, manufacturing processes identified to meet requirements and inspections performed during manufacturing are touched on. For the BSV, the results of the final tests carried out at the manufacturer are also collected, since the construction of this double vacuum chamber is nearing its final stage.