High background radiation areas: the case of Villar de la Yegua Town

Full text: The starting point of the Spanish experience in the study of High Background Radiation Areas is the development of a nationwide indoor radon survey carried out in 1988. This campaign, belonging to the first Spanish Radon Framework, consisted of about 2000 indoor radon measurements which represented a valuable basis to face rigorously the radon issue in Spain. Together with this, since 1991 the Spanish Nuclear Safety Council, the National Uranium Company and several Universities developed the so-called MARNA project with the aim of estimating potential radon emission from external gamma dose rates, radium concentrations in soil and geological parameters. After that, several regional surveys were conducted to determine exposure to natural sources of radiation in different populated high background radiation areas. Among them, Villar de la Yegua Town is the most important area of Spain from a radiological point of view, and the highest indoor radon concentrations, up to 25000 Bq m-3 have been found there. Until now, the main result in this area show a geometric mean radon concentration of 818 Bq m-3, which is 18 times higher than the national value. In this paper, the results coming from the last survey in the Villar de la Yegua Town, carried out during 2004 are summarized. Together with the main result, a geometric mean radon concentration of 1348 Bq m-3, a dose estimation coming from radon inhalation is shown as well as a discussion about the relationship between these results and those predicted by the MARNA project for this area. (author)