The results of nondestructive and destructive examination of the SUPERFACT 1 experiment carried out by both the Transuranium Institute (TUI) and the French Commissariat à I’Energie Atomique (CEA) are reported. This experiment aimed to study the behavior of fuels made up with neptunium or americium (from 2 wt% up to 45 wt% of heavy atoms) under irradiation in the Phénix French fast reactor (FR). Posttest examinations, jointly performed by the CEA and TUI, allowed comparison of this behavior with the standard oxide fuel reference. The experiment’s main results are reviewed. Then, the real interest in the FRs for a high rate of transmutation of actinides is examined, and also, some limitations are discussed.