[en] Very early in its history, nuclear industry has taken care of the future of its wastes. Cementation processes for medium-level activity wastes, vitrification processes for minor actinide solutions and fission products are now proven technologies. The conditioning of wastes is just one ink in the full chain of the waste management process. However, this link is of prime importance because the future of the waste depends on the way it is conditioned. Reciprocally, the storage and disposal largely rely on the confidence given to the behaviour of waste packages with time. The leading role of France in the domain of radioactive wastes conditioning is a strong and valorizable asset at the international industrial plan, but also in terms of social acceptance by showing to the public that technical solutions exist. This monograph takes stock of the conditioning of nuclear wastes and describes the researches in progress, the stakes and the recent results obtained by the CEA (French atomic energy commission). Content: 1 - introduction: waste volumes and fluxes, management strategy, conditioning; 2 - Decontamination and treatment processes for effluent and technological waste; 3 - Glass, a waste conditioning matrix for the long term: Glass packages and manufacturing processes; Nuclear glass formulation, structure and properties; Long-term behavior of glasses; Cold crucible vitrification; 4 - Current conditioning systems for low and intermediate level waste: Cements as confining materials; Bitumens; Metallic structure waste conditioning; 5 - Researching alternative matrices and processes for waste treatment and conditioning: Plasma benefits for incineration / vitrification waste treatment; The Shiva process; Alternative confining matrices; Confinement of waste from pyrochemical processes: status of research; 6 - Spent fuel: a possible confining matrix?: Spent fuel initial characteristics; Spent fuel evolution in a dry storage facility; Modelling the long-term spent fuel behavior; Spent fuel containers in long-term storage and direct disposal concepts; Spent fuel storage and direct disposal: results and outlooks; 7 - general conclusion: Conditioning: a major asset for nuclear waste management; Glossary; Index