High temperatures, irradiation, mechanical stresses, corrosive environments, etc. The materials used in nuclear power plants are subjected to extreme conditions. Guaranteeing the safety, lifespan and performance levels of current reactors, while designing and qualifying new materials capable of resisting the specific constraints of future nuclear systems, are the main issues investigated at the CEA in the field of nuclear materials. To meet these requirements, researchers have access to a wealth of feedback, skills and unparalleled experimental facilities.