Measurement of the natural radioactivity at the international high energy stereoscopic system (HESS) project in Southern Africa

The concentrations of the natural radionuclides 40K, 238U, and 232Th in soil samples taken from the international high energy stereoscopic system (HESS) project in Namibia have been determined using an HPGe detector and found to vary from 10.8±1.4 to 26.4±1.8 Bq kg−1 for 238U, 12.8±2.4–52.3±3.7 Bq kg−1 for 232Th and 212.1±12.1–683.8±27.1 Bq kg−1 for 40K. The corresponding annual effective dose equivalent is 0.06±0.01 mSv y−1 which is less than the limit of 1 mSv y−1 recommended for the public by the ICRP.