An evaluation of the natural radioactivity in Andaman beach sand samples of Thailand after the 2004 tsunami

Following the 2004 ‘Boxing day’ tsunami, a determination has been made of the activity concentrations of 226Ra, 232Th and 40K in beach sand samples which have been collected from various locations along the Andaman coast of the Thai peninsula. Use has been made of a HPGe detector-based, low-background gamma-ray counting system. The natural radioactivity levels of 226Ra, 232Th and 40K measured from these samples was found to lie in the range 1.6–52.5, 0.3–73.9and 2.8–1111.9 Bq/kg respectively for the west coast and 3.5–83.1, 4.5–42.0, and 9.6–1376 Bq/kg respectively for the east coast. The radioactivity concentrations of 226Ra, 232Th and 40K along the Andaman coast are comparable to that of the east coast, which was not exposed to the tsunami. The corresponding annual effective dose varies from 1.6–105.9 μSv/y with a mean value of 59.1±0.3 μSv/y, significantly lower than the worldwide average as reported by United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) (2000).

► 226Ra, 232Th and 40K-levels were obtained from Andaman coast sand, Thailand.
► Differences between west and east-coast sand levels are insignificant.
► The annual outdoor effective dose is below the worldwide average value.
► The presence of artificial radionuclides was not detectable.
► The monitored areas are at the typical local level of natural radioactivity.