Safety assessments are the main pillars of the analysis of the impact of storage of the spent nuclear fuel. There are many scenarios to describe what might happen during the storage and disposal time of the nuclear waste. Even though the main composition of the spent nuclear is UO2, the matrix contains transuranium elements and fission products, which have different chemical behaviour and lead to an altered physical state after the irradiation. Thus, the complex nature of the spent nuclear fuels requires understanding of several mechanisms through investigation of individual parameters and their effect on one and another. This is achieved by single effect studies, starting from simple systems to gradually more complex systems. In this thesis, thin films have been used as model systems to simulate the spent fuel in a systematic manner. The main focus was given to the actinide (mixed) oxides (Th, U, Np, Pu, and Ce as surrogate for Pu and as fission product). Throughout this thesis, the suitability of the use of thin films instead of bulk material has been demonstrated, and the investigation of redox properties of model systems for spent fuels using different methods is described.