NATURAL RADIOACTIVITY AND EVALUATION OF RADIATION HAZARDS IN SOILS FROM GRANITOIDE-GRANITE GEOLOGICAL FORMATION IN CUBA

The natural radioactivity and the associated radiation hazards of soils from the Cumanayagua Granitoide-Granitic massif in the central south of Cuba have been studied. Mass activities of the natural radionuclides U-238, Th-232 and K-40 varied in the ranges 10.4-33, 4.6-21.7 and 381-1201 Bq kg(-1), respectively. The radium equivalent activity (91.4 +/- 22.1 Bq kg(-1)), absorbed dose rate (45.6 +/- 11.1 nGy h(-1)), annual effective dose rate (56.1 +/- 13.7 mu Sv y(-1)) and the external hazard index (0.25 +/- 0.06) have been calculated and compared with the internationally approved values. According to these results, the area can be regarded as an area with normal natural background radiation and may not pose radiological risks to the inhabitants owing to harmful effects of ionizing radiation from the natural radionuclides in soils. This study provides background radioactivity concentrations in Cumanayagua Granitoide area and generate a baseline data for radiological mapping of Cuba in the future.