The project simulates releases of atmospheric radioactivity from various sources, as well as the response from measurement systems. In the context of detecting releases of radioactive substances into the atmosphere, simulations of the transport of particles from some point of release to a detection point are needed. Utilizing atmospheric transport modelling tools, the dispersion of particles from an arbitrary selected release point to some other selected location on the surface of earth is planned to be simulated. The results of the calculations will be the basis for a large-scale library to be used for further studies.