Superior Accident Tolerant Fuel via Enhanced Technology (SAFETY)

Research Project, 2018 – 2023

Improved resilience of nuclear fuel to high temperatures will reduce dramatically the consequences of potential accidents. The two relevant components of the resulting accident tolerant fuel comprise the fuel itself and the cladding. Improvements of cladding tubes are sought by applying coatings. Here, a conventional cold spray chromium coating as well as novel candidate coatings will be studied. The fuel in turn can be improved by replacing traditional UO2 pellets by UN pellets. Besides high density and superior thermal conductivity, it can be designed to reduce the release of harmful substances, thus avoiding severe effects of any accidents. In addition, novel approaches to considerably enhance the corrosion resistance of UN will be explored to increase the safety margins even more. Coated fuel systems will be characterised both in the as-produced condition and after exposure to oxidizing conditions, including irradiation in the Halden reactor. Characterization will include electron microscopy, atom probe tomography and non-destructive gamma emission tomography. Experiments will be complemented by first-principle modelling to obtain mechanistic understanding of the oxidation phenomena including influence of irradiation. Performance under normal operation conditions as well as under simulated accident conditions will be evaluated. A level of understanding of the new fuel is sought, such that it can be implemented in a ten-year perspective produced by Swedish companies.