Global climate change, record-high oil prices and the deceasing availability of fossil fuels are forcing us to rethink the way we deal with our energy needs. In response to this growing concern, and as an indication of the seriousness of these issues, the current administration of Tunisia is executing strategic plans to increase green energy sources. Nuclear energy is one such alternative source. The evaluation of the transport in the atmosphere of radioactive substance discharged from a nuclear power plant under normal operational or accidental conditions is a requirement of design and licensing. The atmosphere is a major exposure pathway by which radioactive materials that are either routinely discharged under authorization or accidentally released from a nuclear power plant could be dispersed in the environment and transported to locations where they may reach the public. In this paper, the development plan for nuclear energy in Tunisia will be introduced, and the atmospheric dispersion model of radioactive substance for the two sites in Tunisia will be presented. The meteorological parameters for specific site will be illustrated with the evaluation of the meteorological investigation. Contamination in the air and on the ground over short and long time periods will be described in the atmospheric dispersion models. Several related issues will be discussed, including the suitability of the meteorological investigation, appropriateness of the dispersion models, etc.