Contribution to the study of Portuguese population exposure to gamma radiation

The initiation and development of a programme of surveying gamma radiation in Portugal is reported. Outdoor measurements of gamma radiation levels were carried out all over the country, contributing first estimates towards the establishment of a radiological map. Three specific regions were studied in more detail. One of them is well known as a high background area where uranium mines are in operation and the other two are related to sites selected for the installation of nuclear power plants. Indoor measurements in dwellings were made in two specific areas. Distrito de Viseu and Distrito de Braganca, respectively, of high and medium radiation levels. These values are insufficient to give a complete picture of the population exposure but they give an overview of the average dose rates in the country and an estimate of the average population doses for two particular regions. (author)