|
چکیده
|
Natural radioactivity of 30 granite rock samples collected from Alvand plutonic complex was determined using a high‑resolution, high purity germanium gamma‑spectrometry system. The activity concentrations of 226 Ra, 232 Th and K varied from 8.4 ± 0.6 to 119.3 ± 1.9, i.e., minimum detectable activities (MDA) to 268.4 ± 3.3 and 62.9 ± 4.1 to 1602.6 ± 27.9 Bq/kg, respectively. 40 Cs ranged from MDA to 4.9 ± 0.7 Bq/kg. The radium equivalent activity varies between 35.7 and 624.2 Bq/kg that is lower than the permitted value (370 Bq/kg) except in three samples. The absorbed dose rate ranged from 17.9 to 282.8 nGy/h, and the effective dose rate outdoor was determined to be between 21.9 and 347.0 µSv/y. The annual effective dose rate indoor varied from 87.8 to 1388.2 µSv/y that is lower than the dose criterion, 1 mSv/y, except for PGG(W) and GRG(W) samples. The internal and external hazard indices values range from 0.1–2.0 to 0.1–1.7, respectively, only four out of 30 showed values higher than unity. 137
|