The fusion reactor ARC proposed by MIT is a concept of high-magnetic field reactor, using high temperature superconductors (HTS), with an innovative liquid breeding blanket (BB) made of a molten salt (FLiBe). The plasma chamber and the vacuum vessel are contained in the liquid blanket and the FLiBe is used also for the cooling of the vacuum vessel and of the divertor. The lithium (isotopically enriched with 90% 6Li) contained in the molten salt has the aim of producing tritium after the interaction with the neutrons released by the fusion reactions. FLiBe is then extracted from the breeding blanket andsent to a heat exchanger to finally produce electricity with a traditional thermodynamic cycle.