Measurements of NORM in beach sand samples along the Andaman coast of Thailand after the 2004 tsunami

A hyper-pure germanium detector-based gamma-ray spectroscopy low background counting system was used to determine the levels of natural radioactivity from beach sand samples along the Andaman coast of Thailand following the 2004 tsunami. The activity concentrations of 226Ra, 232Th and 40K were found to lie in the range of 2.7±0.1↔23.5±0.4, 3.0±0.1↔34.6±0.6, 10.7±0.9↔654.3±21.6 Bq kg−1 respectively. The total gamma absorbed dose rate in air at 1 m above the ground surface ranges from 3.5±0.1 to 52.8±0.9 nGy h−1 with an average value of 31±1 nGy h−1 corresponding to annual effective dose of 0.038 mSv. The latter was found to be significantly lower than the world average value of 0.07 mSv y−1 for outdoor annual effective dose, as reported by UNSCEAR(2000) but consistent with values for sand found by others. The results from this study will be used to establish a radiological baseline map in Thailand and used as reference information to assess any alterations in the radioactivity background level due to the changes in the topography of the location, other developments around the area or any artficial influences on the environment.