Measurement of natural radioactivity and radium equivalent activity for pottery making clay samples in Paraíba and Rio Grande do Norte – Brazil

High levels of environmental radioactivity are caused by the composition of minerals in the earth’s crust and the impact of prospection and utilization of natural sources, mainly due to the presence of 40K and radionuclides of 238U and 232Th series. Radium equivalent activity (RaEq) was calculated to assess the risk associated with primordial radionuclides.