This research aims to study the specific activity of natural radioactivity in groundwater samples taken in the area of Phra Nakhon Si Ayutthaya Province, Thailand. Totally, sixty groundwater samples collected from wells in eight districts were monitored and determined for radionuclides 226Ra, 232Th and 40K and gross alpha and beta were determined using high resolution gamma spectrometer and Canberra Tennelec Series 5 gas flow proportional counter, respectively. Most of the sixty wells serve for water consumption and some other wells for agricultural. The results showed that the average activity concentrations of the gross alpha and beta were 0.01±0.007 and 0.15±0.02 Bq L-1 and the specific activity of 226Ra, 232Th and 40K were averagely 0.77±0.13, 1.03±0.19 and 15.56±1.28 Bq L-1, and respectively. The activity concentrations of the gross alpha and beta and the specific activity of the radionuclides in these samples exhibited quite low as compared to the recommended reference level for human consumption reported by World Health Organization (WHO).
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.
Abstract. Thailand Institute of Nuclear Technology (TINT) has continuously monitored radiation exposure and radionuclide in workplaces specifically radon gas to estimate effective dose for workers. Radon exposure is the second leading cause of lung cancer in the world. In this study, radon in air and tap water at building no. 3, 7, 8, 9 and 18 on Ongkharak site of TINT have been measured for 5 years from 2012 to 2016. Radon level in air and tap water were investigated on 83 stations (workplaces) and 54 samples, respectively. Radon concentrations in air and tap water were measured by using the pulsed ionization chamber (ATMOS 12 DPX). Indoor radon concentrations in air were in the range of 12-138 Bq.m -3 with an average value of 30.13±17.05 Bq.m -3 . Radon concentrations in tap water were in the range of 0.10 to 2.89 Bq.l -1 with an average value of 0.51±0.55 Bq.l -1 . The results of radon concentrations at TINT were below the US Environmental Protection Agency (US EPA) safety limit of 148 Bq.m -3 and 150 Bq.l -1 , for, air and tap water, respectively. The average effective dose for TINT's workers due to indoor radon exposure was approximately 0.20±0.11 mSv.y -1 . The value is 100 times less than the annual dose limit for limit occupational radiation worker defined by the International Commission on Radiological Protection (ICRP). As a result, the TINT's workplaces are radiologically safe from radon content in air and tap water.
The radioactive nuclides were a cancer causing agent. They have a source of origin from nature and man-made. The natural radioactive elements were found in granite rock. The purpose of this research were analyze the activity of radioactive nuclides (226Ra, 232Th and 40K) in herbs and forage plant samples from Koh Phangan District, Surat Thani Province and to analyze the Annual external effective dose rate (E). A total of 20 species of plants, including medicinal plants and food chains plant were randomly sampled. The plant samples were analyzed by the gamma spectrometry system with high-purity germanium (HPGe) detector. It was found that the radioactive nuclides of 226Ra, 232Th and 40K were ranged from 6.75 ± 0.16 to 61.55 ± 0.48, 1.76 ± 0.15 to 34.24 ± 0.25 and 330.74 ± 0.37 to 1337.54 ± 0.64 Bq/kg, respectively. In addition, the Annual external effective dose rate (E) in all plants were lower than required (UNSCEAR, 2000).
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