Reference levels of natural radioactivity for the beach sands in a Brazilian southeastern coastal region

• Published in: Radiation measurements Vol. 40; no. 1; pp. 76 - 83
• Main Authors: Alencar, A.S., Freitas, A.C.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.09.2005; Elsevier
• Subjects: Beach sands; Brazil; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Gamma dose rate; Geochronology; Isotope geochemistry. Geochronology; Natural radioactivity; Pollution, environment geology; Reference levels; Brazil; Brazil, Ilha Grande; Brazil; Reference levels; Gamma dose rate; Natural radioactivity; Beach sands; South America; risk assessment; gamma rays; potassium; concentration; radionucleids; Natural radioactivity: Reference levels; in situ; beaches; sand; thorium; radioactive decay; uranium; K-40; U-238; Th-232; radioactivity
• ISSN: 1350-4487; 1879-0925
• DOI: 10.1016/j.radmeas.2004.08.003

Gamma dose rates of ten beaches in Ilha Grande, an island of Brazilian southeastern cost, were measured in situ using an environmental radiation detector. The values ranged from 62 nGy h - 1 at Dois Rios Beach to 126 nGy h - 1 at Preta Beach. The activity concentrations of radionuclides 232 Th series, 238 U series and 40 K in three different sand profiles (0–10, 10–20 and 20–30 cm) were measured using gamma ray spectrometry and the result is shown in Bq kg - 1 . In most of the cases, eight out of ten beaches, 40 K was the main contributor to the calculated local gamma dose rate. The annual effective doses were 0.15 ± 0.03 mSv yr - 1 for Preta and 0.10 ± 0.02 mSv yr - 1 for Caxadaço beaches, while in the others beaches the mean value of annual effective doses was 0.08 mSv yr - 1 . None of the beaches analysed were considered a radiological risk.