Radioactive anomalies in a northeastern Brazilian town

Abstract
The Brazilian town of Santana do Matos is located in a region which is rich in granites and other pre‐Cambrian rocks. Radiological measurements performed in 43 dwellings by a hand‐held scintillometer, gave a mean value of 148 ± 44 nGy h‐1. Readings in downtown streets ranged from 200 to 330 nGy h‐1. Several radiocative anomalies with high γ‐background were also located in the surroundings of that town, where a value of 900 nGy h‐1 was recorded in a small cave used as a shelter by some shepherds. Concentrations of naturally occurring radionuclides in seven samples of building materials utilized at Santana do Matos, were determined by a gamma spectrometer. The following mean values were obtained: 226Ra: 40.1 Bq kg‐1; 232Th: 68.8 Bq kg‐1; 40K: 736 Bq kg‐1.

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