Nuclear safety research programmes in the European Commission's Joint Research Centre cover aspects related to the behaviour of the reactor system, of the nuclear fuel during in-pile irradiation and of spent fuel thereafter. Several projects at JRC-ITU are dedicated to the study of properties and behaviour of nuclear fuel compounds under normal and off-normal conditions, including severe accident characterized by fuel rod degradation, core meltdown and radionuclide release. Safety relevant aspects associated with spent fuel during cooling and storage after discharge from the reactor, and for final disposal in a geologic repository are also studied. At JRC-IRMM a non-destructive method to determine the fissile content of melted fuel is under development. In 2012 JRC-IET established a new team, with strong expertise on nuclear accident modelling to contribute to European post-Fukushima efforts to update the Severe Accident Management strategies and practices. A major component of this team's work is the support to development and validation of the Reference European code ASTEC (Accident Source Term Evaluation Code) developed by IRSN (France) and GRS (Germany) for light water reactors severe accident analyses and source term evaluation.