Determination of the dose rate from external irradiation. Geological considerations in sampling optimization

Dose rates received from natural external irradiation were evaluated with two techniques: using radiation measurements made in radiometric flights, and using gamma-emitter radioactivity levels in the soil. The zone of the study was the province of Cáceres (Spain), of some 20 000 km2 area. Because of its complicated geology, this zone has a great spatial variability in the concentrations of radionuclides present in the soil. The results allowed ratification of the two dose rate measurement techniques, and the establishment of criteria with which, using geology as a parameter, future sampling campaigns could be optimized through the determination of the minimum number of points to sample and their most suitable locations.