A very high intensity particle accelerator, built by INFN, has left the National Laboratories of Legnaro (LNL) of the INFN to Japan, for the prototype of the International Fusion Material Irradiation Facility. The accelerator, projected and realized by a team of physicists and engineers from LNL and INFN of Padua, Turin and Bologna, leaded by Andrea Pisent, will produce in Japan a flux of very intense neutrons to make a test of future nuclear fusion power plants.