RESUMEN
Estimation of terrestrial external radiation is essential for assessment of public exposure to natural radiation. During national survey of natural radionuclide in soil in Iran, 979 soil samples were collected from different locations, in the same time ambient dose equivalent rate was measured by a scintillator detector. In this work, terrestrial radiation was estimated by direct measurement of ambient dose equivalent rate of background radiation. The response of dose measuring instrument to cosmic radiation at ground level was measured and other components were discussed and estimated. For verification, terrestrial radiation derived from this method was compared with those calculated from activity concentration of natural radionuclides in soil. The averages of ambient dose equivalent rate derived from activity concentration of by natural radionuclide in soil and from direct measurement are 55.07 and 62.57 nSv/h, respectively. The source of statistical and systematic uncertainties are introduced and discussed.
