Natural radioactivity assessment by gamma spectrometry in some commercially-used granites from Paraná State, Brazil: Preliminary results

Environmental Radiometric Division, Instituto de Pesquisas Energéticas e Nucleares Av. Prof. Lineu Prestes, 2242, Cidade Universitária, 05508-000 São Paulo, SP, Brazil

Abstract

Natural radioactivity concentrations in commercially-used granites from Paraná state, Brazil, were measured in order to estimate the potential radiological hazard to mankind due to granite as an ornamental building material through the ²²⁶Ra, ²³²Th and ⁴⁰K activities concentrations measured in several samples by high-resolution gamma-ray spectroscopy. Preliminary results, without considering samples self-attenuation, show activities concentrations varying from 4 ± 1 Bq kg⁻¹ to 79 ± 3 Bq kg⁻¹ for ²²⁶Ra, 7 ± 1 Bq kg⁻¹ to 142 ± 6 Bq kg⁻¹ for ²³²Th and 214 ± 14 Bq kg⁻¹ to 1626 ± 77 Bq kg⁻¹ for ⁴⁰K. All results are within the range of literature values for similar rocks. Further, the annual effective dose, the radium equivalent activity and the external and internal hazard indexes will be assessed.