Radioactivity from medical isotope production facilities, nuclear power plants and nuclear research reactors has accumulated in the atmosphere. Observations from ground-based instruments indicate that the levels can vary significantly, in part due to seasonal changes in weather patterns and regional differences in sources. Atmospheric Transport Modelling (ATM) is often used to study the transport and dilution of atmospheric radioactivity from known sources. In this project, we request computational time to study meteorological uncertainties in ATM simulations used for radioxenon background estimation by performing a model intercomparison of two commonly used transport models for atmospheric radioactivity.