New generation high power hadron accelerators are more and more required to produce intense fluxes of secondary particles for various fields of science: radioactive ions for nuclear physics, muons and neutrinos for particle physics, and of course neutrons for many applications like condensed matter physics, solid-state physics, or irradiation tools. This paper will focus on the applications of such accelerators in support of nuclear energy, and in particular on the two following cases: the International Fusion Materials Irradiation Facility (IFMIF), which asks for a 10 MW, 40 MeV deuteron beam, and the ADS (Accelerator Driven System) application for transmutation of long-lived radioactive wastes, which typically requires a 600 MeV - 1 GeV proton beam of a few mA for demonstrators, and a few tens of mA for large industrial systems. In this respect, the status of the accelerator proposed for the European MYRRHA project will be detailed and discussed.