FRIENDS (Fleet of dRones for radIological inspEction, commuNication anD reScue) is a project of research and development that addresses the quick characterization of the geographic extent of radiological contamination by a fleet of drones equipped with advanced technologies of sensors. This project is supported by the FCT, Compete 2020 and Lisboa 2020 under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). Goals are real-time mapping of both the scenario and the contamination level of a given area, autonomous and cooperative navigation of a fleet of drones to cover this area in an optimal way, in closed-loop with the real-time construction of the contamination map, while maintaining radiation exposure of the drones at a safe level, and wireless data communication among the drones and the ground station. The advances in the state of the art that we expect to achieve in this project will be validated using real drones along with real (but low level) radiation sources.