Assessment of natural radioactivity and gamma-ray dose in monazite rich black Sand Beach of Penang Island, Malaysia

Activity concentrations of primordial radionuclides in sand samples collected from the coastal beaches surrounding Penang Island have been measured using conventional gamma-ray spectrometry, while in-situ gamma-ray doses have been measured through use of a portable radiation survey meter. The mean activity concentrations for Ra-226, Th-232 and K-40 at different locations were found to be less than the world average values, while the Miami Bay values for Ra-226 and Th-232 were found to be greater, at 1023 +/- 47 and 2086 +/- 96 Bq kg(-1) respectively. The main contributor to radionuclide enrichment in Miami Bay is the presence of monazite-rich black sands. The measured data were compared against literature values and also recommended limits set by the relevant international bodies. With the exception of Miami Bay, considered an elevated background radiation area that would benefit from regular monitoring, Penang island beach sands typically pose no significant radiological risk to the local populace and tourists visiting the leisure beaches. (C) 2017 Elsevier Ltd. All rights reserved.