Safety aspects of oxide fuels for transmutation and utilization in accelerator driven systems

General safety aspects of fuels under development for accelerator driven systems (ADS) are reviewed and discussed. These fuels should allow a maximization of transmutation and incineration rates, which excludes fertile UO2 as a component or matrix. The accumulated knowledge on data, phenomena and scenarios of fast reactors with (U,Pu)O2 oxide fuels and sodium cooling serves as background for this review. For future ADS both the reactor system itself, the fuel and the coolant are innovative compared to traditional critical fast reactors. For the fuel, these boundary conditions lead to many open questions, starting from basic thermal physical, thermal mechanical and irradiation data to the behavior under transient conditions. The choice of fuel naturally has a significant impact on whole core behavior and safety too, including the influence on related neutronics parameters, on failure propagation and disruption behavior under accident conditions. Key safety issues are discussed and a first assessment of phenomena and scenarios is given. Areas of research and technology in which further work is required to resolve important safety issues are highlighted.