Nickel-based alloys are structural materials of choice for Molten Salt Reactors (MSRs). They offer excellent mechanical properties and good corrosion resistance. In these materials, helium production, mainly caused by the transmutation of nickel by fast neutrons, can reach levels sufficient to strongly embrittle the material or cause it to swell under irradiation. Helium is hardly soluble in the material, and condenses in the form of bubbles or segregates at grain boundaries. To limit these phenomena and successfully trap the helium, one solution is to introduce into the material to be irradiated a high density of nanoprecipitates, whose interfaces will serve as germination sites for nanometric bubbles capable of trapping the helium atoms, preventing the latter from migrating to the grain boundaries and degrading the material's performance. Corrected transmission electron microscopy will be used to study the precipitation kinetics of the thermodynamically expected phases, as well as the atomic structure of the interfaces formed between the precipitates and the matrix. A phase-field simulation of precipitation will also be considered. Finally, the He trapping mechanisms at the interfaces will be studied using electron energy loss spectroscopy (EELS).