Natural and man-made radionuclides in the soil of a nuclear facility site located in a coniferous forest in central Mexico

Abstract

137Cs, 226Ra, 40K and 235U in surface soil samples and 222Rn levels at different depths in the soil were studied at the Nuclear Centre of Mexico located in a forest at 3000 m altitude. The gamma emitters in the soil samples were measured with a low level counting gamma spectrometer and soil radon concentration was determined using Solid State Nuclear Track Detectors. The results indicate that the specific activities of 137Cs, 226Ra and 235U were in general below the recommended screening limits for surface soils from open fields and forested sites, except at one small area where a moderate punctual contamination was found. The 222Rn values confirm that 226Ra contamination in the soil was of low level and superficial.