[en] Because of the promised shutdown and decommissioning of the French Superphenix fast breeder reactor, the French research programs on transmutation will be reoriented towards the smaller Phenix reactor. This issue of 'DRN Actualites' brochure reports on the works carried out by the operator with the help of the Direction of Nuclear Reactors (DRN) of the CEA and Novatome company to satisfy the nuclear safety authorities requirements for the start-up of the Phenix reactor. Three aspects are developed: the 'Service life' project which concerns the non-destructive control of the reactor core and primary circuit, the seismic behaviour of the installation (diagnostic and reinforcement), and the renewal of the secondary circuit and steam generators. (J.S.)