The map of natural radiation and dosimetric of Spain (MARNA project)

One the consequences of the Chernobyl accident (April 1986) was a great public and governmental concern on the incidence and effects of nuclear radiations in the environment. In order to determine the importance of a possible problem, two fundamental question immediately arose: 1) What is the amount of contamination produced and what is its incidence in the world fallout levels. 2) What is the natural radiometric background in the areas is which the affect population lived. In order to answer these two questions the experts looked at the already existing radiometric data banks. Those countries that in the past developed radiometric surveys, mainly related with Uranium prospecting actives, tried to use the data so generated. In the USA, for example, the spectrometric data produced by the project ''National Uranium Resources Evaluation'' (NURE) were employed to help producing national radiometric maps. In Spain, the data obtained in aerial prospections made during the thirty years of existence of the now finished Plan Nacional de Exploration e Investigation del Uranio (PNEIU), provided data for approximately 2/3 of the national territory. These data provided a continuous register for the total gamma radiation. In some cases additional discrimination of the contributions from Uranium, Thorium, Potassium, Cosmic radiation and Radon was also given. The aerial produced data were complemented in some areas by land measurements made using portable instruments carried either on foot or by car. (Author)