Development of fuel-model interfaces: Investigations by XPS, TEM, SEM and AFM

The presented work aims to reproducibly prepare UO2–Pd thin film model systems for spent nuclear fuel in order to further investigate surface reactions of these films under relevant redox conditions. The sputter co-deposition of U and Pd (fission product) in the presence of O2 results in the homogenous distribution of Pd in a crystalline UO2 matrix. Heating the films causes the diffusion of film components. Hereby, the formation of ε-particles has to be clarified. First electrochemical studies show the influence of the nobel metal Pd on the redox behaviour of UO2. With increasing Pd concentration the matrix dissolution is decreased. However, we could demonstrate that blocked oxidation processes are of temporary nature. The passivation of the Pd reactive sites with increasing number of cycles finally induces the approximation of the mixed system to the redox behaviour of the pure UO2 system.