Though it is a well-defined industrial product that has been duly tested over several decades, nuclear fuel nonetheless remains the focus of numerous innovations. It needs to be optimised on a regular basis not only to meet economic and industrial imperatives, but also to prepare for the future and any emerging issues. And for good reason, since nuclear fuel is a complex and complicated product to use, which requires reconciling ever-increasing performance and safety requirements. Researchers at the CEA are rising to this challenge, by bettering our control over the knowledge and skills accumulated in all fields from design to post-irradiation characterisation and numerical simulation.