Measurement of natural (40K, 226Ra and 232Th) and anthropogenic (137Cs) gamma radiation and radiological hazard assessment in beach sand samples collected from Ao Phrao at Koh Samet in Rayong province (Thailand)

Abstract

In the present research, the main objectives were to measure and analyze the specific activities of natural (40K, 226Ra and 232Th) radionuclides in 30 beach sand samples collected from Ao Phrao after the Rayong oil spill disaster. This huge Petroleum Authority of Thailand (PTT) oil spill occurred on July 27, 2013, in the Gulf of Thailand nearby Ao Phrao at Koh Samet in Rayong province in eastern region of Thailand. At the same time, anthropogenic (137Cs) radionuclides accumulated in the studied area was also studied and presented. High-purity germanium (HPGe) detector with a massive lead shield, some standard reference material sources and gamma spectrometry technique, were used to measure and analyze all of the experimental results. The frequency distribution of specific activities of 40K, 226Ra, 232Th and 137Cs were also evaluated and found to be the asymmetrical distribution. The median values of 40K, 226Ra, 232Th and 137Cs were 173.55 ± 67.04, 10.76 ± 1.71, 6.35 ± 0.75 and 0.24 ± 0.10 Bq/kg, respectively. Furthermore, the associated radiological hazard indices for the studied area were calculated and compared to nationally and internationally recommended values. It was found that the beach sand samples from the study area provide no excessive exposures created from the oil spill for inhabitants. Moreover, the radioactive contour maps of the investigated area were also imaged and presented in this study. The data presented in the study are importance since they create the baseline of the radiological hazard data and mapping of the investigated area in the future.