Analogous materials for studying spent nuclear fuel: The influence of particle size distribution on the specific surface area of irradiated nuclear fuel

Knowledge of the reactive surface that a given material presents to reactive species is one of the fundamental factors for the discussion of experimental data from the alteration of a solid at laboratory scale, or the extrapolation to different environmental conditions. The reactive surface depends on several factors such as the origin of the solid, for example, history of irradiation, the particle size distribution and the history of its reactive surface. Here we discuss the relation between the particle size distribution and the specific surface area for different uranium oxides, namely, irradiated fuel, SIMFUEL and several fresh – non-irradiated – uranium oxides. The analysis is made comparing our own data with values reported in the literature. Our analysis strongly suggests that it is necessary to establish the surface area time evolution in order to model its behaviour in different scenarios where the alteration process will happen. Moreover, this is required in both, dry and wet conditions. A first step to get this function is the determination of the particle size distribution dependence of the specific surface area.