Estimation of Rn-222 exhalation rate and assessment of radiological risk from activity concentration of Ra-226, Th-232 and K-40

摘要

The activity concentration of natural radionuclides and Rn-222 (Radon) exhalation rate in soil samples were determined using NaI gamma detector and Scintillation based Smart Radon Monitor (SRM). Soil samples were collected from different geological formations of the same area. The concentration of three radionuclides (Ra-226, Th-232 and K-40) in the studied area has been varied from 25 Bq kg(-1) to 48 Bq kg(-1), 28 Bq kg(-1) to 47 Bq kg(-1) and 356 Bq kg(-1) to 598 Bq kg(-1) respectively. The average value of Ra-226 (Radium) equivalent activity in soil samples of the studied area was 125 Bq kg(-1). The Ra-226 equivalent activities of soil samples have been calculated to assess the radiation hazards arising due to the use of these soils in the construction of dwellings. The exhalation of Rn-222 from the earth's crust and building material are the main source of Rn-222 in indoor environment. The Rn-222 exhalation rate in the studied area was varied from 16.9 +/- 0.5 mBq Kg(-1) h(-1) to 38.2 +/- 0.9 mBq Kg(-1) h(-1). A weak correlation was obtained between the Ra-226 and Rn-222 exhalation rate. The annual effective doses for different organs and radiation hazards have been also calculated in the studied area. The overall average annual effective dose in the studied is lower than the world recommended value of 1.0 mSva(-1).