Natural radiation exposure in the Campo Arañuelo region in the surroundings of Almaraz nuclear power station (Spain)

In order to make a more accurate assessment of the dose coming from radon in this area, a new and more extensive survey on indoor radon with a total of 380 measurements was carried out in 2000 in the Campo Arañuelo region around the Almaraz nuclear power station. From the results obtained in this survey, a population-weighted mean annual effective dose from radon exposure of 1.7 mSv y−1, 44% lower than that previously reported in 1998, was estimated for the whole Campo Arañuelo region. The maximum dose value due to radon exposure, about 4 mSv y−1, was reached in the so-called La Vera area located in the north of this region. The relationship between the indoor radon concentrations experimentally measured, the geological characteristics of this geographic area and the information provided by the radiation map of the Spanish MARNA Project is also analyzed, confirming that La Vera area should be considered as a high radon level area.