[en] This report presents the guiding principles of researches on nuclear systems of 4. generation, more particularly their ability to ensure a sustainable management of materials and wastes (stakes and market of fourth-generation fast breeder reactors), but also the different currently studied systems, and possible scenarios of progressive deployment of these systems in France. It also presents results obtained in the fields of plutonium multi-recycling and of separation-transmutation of long life radioactive elements. It presents choices proposed for the Astrid technological demonstrator (a sodium-cooled fast breeder reactor), research actions to be undertaken and the possible agenda for its realisation.