[en] In the last years the demand of electricity is growing at high rates, particularly in the emerging countries, as a result of the industrial development process as well as by the improvement of the quality of life of the population, which is strongly linked to the increase of the per capita electricity consumption. Then, all forms of energy resources, technically feasible of use, economically viable and environmentally acceptable, should be explored for energy generation. MESSAGE (Model for Energy Supply Strategy Alternatives and Their General Environmental Impacts) is a dynamic linear programming model, currently disseminated by IAEA (International Atomic Energy Agency), for optimization of energy supply systems, development of scenarios and energy policy analysis [1]. This paper presents the main features of the model and a simplified case of system expansion, with the solely purpose of demonstrating operational aspects and the potential of the code version available at CDTN. Nowadays, the nuclear option is considered a preferential alternative, among several others, for the expansion of electricity supply, mainly due to its reduced greenhouse gas emissions. Among others factors, climate change constitutes one of the most serious threats for energy sustainability in the long term. In this context, CDTN intends to conduct or participate in studies using the MESSAGE model to evaluate the competitiveness of nuclear power plants considering different expansion scenarios for the Brazilian electric system. (author)