No abstract

In this study, systematic measurement of activity concentrations of 40 K, 226 Ra, and 232 Th and radon exhalation rate has been done in soil samples of Cauvery River environment. The activity was measured using HPGe gamma-ray spectrometer, and the mean values of 40 K, 226 Ra, and 232 Th in the soil samples were found to be 182 ± 4, 34 ± 2, and 19 ± 1 Bq kg −1 , respectively. The radon exhalation rate was measured by "Can technique" using SSNTD (LR-115) films. The mean values of radium concentration, surface exhalation, and mass exhalation rate were found to be 118.95, 293.61, and 108.53 mBq kg −1 h −1 , respectively. The radiological hazard indices due to natural radioactivity were calculated and compared with international recommended values, which are lower than the recommended level. The radon exhalation rate is lower than the recommended level.

The paper deals with the study of natural radioactivity in the rocks of Coorg district, Karnataka state. The samples were analyzed by NaI(Tl) based gamma ray spectrometer. The activity of 232 Th varies from 16.46 Bq kg À1 to 160.84 Bq kg À1 with mean value of 79.05 Bq kg À1. The activity of 40 K varies from 96.72 Bq kg À1 to 933.68 Bq kg À1 and that of 226 Ra was found to vary from BDL to 34.36 Bq kg À1. A correlation coefficient of R ¼ 0.81 was found between 232 Th activity and 40 K activity. The correlation between 226 Ra activity and 232 Th activity is R ¼ 0.59. The correlation between 40 K and 226 Ra is R ¼ 0.51. The Radium Equivalent Activity (Ra eq) ranges from 46.78Bq kg À1 to 315.55Bq kg À1. The absorbed gamma dose rate (D) ranges from 21.28 nGy h À1 to 141.45 nGy h À1 , with an average of 73.37 nGy h À1. The radionuclides activity was compared with world average values. The external Hazard index (H ex) varies from 0.12 to 0.84. The internal hazard index (H in) is in the range 0.15e0.89. The hazard indices were found to be within safety limits.

The paper presents the activity concentrations of Th,Ra and K in the sediments and river bank soil samples collected from the Kallada river environs of coastal Kerala. The radiological risks associated with these radionuclides were calculated. The samples were processed following standard procedure, and activity was counted using a high-efficiency 5″ × 5″ NaI (Tl) detector coupled to GSPEC gamma spectroscopy system. The mean values of measured activities ofTh, Ra andK in soil samples were found to be 98.1 ± 0.4, 60.3 ± 1.1 and 343.4 ± 1.8 Bq kg, respectively, which results in an average absorbed dose rate of 103 nGy h The corresponding values for sediment samples were found to be 88.0 ± 0.4, 48.6 ± 0.9 and 423.2 ± 2.0 Bq kg, respectively, with a resulting absorbed dose rate of 95 nGy h Radium equivalent activity, annual effective dose equivalent, the external and internal hazard indices were determined and compared with recommended limits. The results of the work provide background data on natural radioactive isotopes, which are useful in the assessment of human radiation exposure from natural environment. The accumulation of information on natural radiation is of great value for radiation protection.

Systematic studies were carried out to understand the distribution of natural radionuclides in sediments and radon in water in the riverine environs of Cauvery, one of the major rivers of South India. The activity of radionuclides in the sediment was measured by gamma ray spectrometry. The radon emanation from the sediment was measured by the sealed 'can technique' and the radon in the water was measured using the RAD-7 instrument. The mean values of K,Ra, and Th in the sediment samples were found to be 297.3 ± 4.16 Bq kg, 75.1 ± 2.64 Bq kg, and 85.5 ± 2.62 Bq kg, respectively. The mean activity of radon, radon exhalation rate, and radium content were found to be 135.68 Bq m, 327.1 mBq m h, and 133.03 mBq kg, respectively. The radon in the water ranged from 0.19 kBq m to 1.40 kBq m. The hyper pure germanium gamma spectroscopy measured via Ra activity and the radon activity measured by the passive can technique showed good correlation. The mean value of radon in the water was within the internationally recommended level. The sediment was considered safe for the purpose of construction, except for some extreme values, and the water was deemed safe for drinking.