Measurement of Natural Radioactivity, Radon Exhalation Rate and Radiation Hazard Assessment in Indian Cement Samples

AbstractBuilding materials are assumed to be the second source of Radon inside buildings. Due to low level of radon emanation from these materials, long term measurements are needed. Radiation doses from the building materials vary depending upon the natural radionuclides 226Ra, 232Th and their daughter products and 40K present in them. Cement is the main and important component used in the construction of buildings in many countries. These radio nuclides pose exposure risk due to their gamma ray emission and internally due to radon and its progeny that emit alpha particles. In the present study radon exhalation rate and the activity concentration of 226Ra, 232Th and 40K radionuclides in cement samples used in Aligarh region (U.P.), India have been measured by “Sealed Can technique” using LR-115 type II detectors and a low level NaI (Tl) based gamma ray spectrometer, respectively. From the measurements activity concentration of radionuclides 226Ra, 232Th and 40K vary from 9 to 28 Bq kg-1, 21 to 43 Bq kg-1 and 280 to 554 Bq kg-1 with overall average value of 19 Bq kg-1,35 Bq kg-1 and 406.7 Bq kg -1 respectively. Radon equivalent activity (Raeq) and external hazard index (Hex) have been found to vary from 60.8 to 121 Bq kg-1 and 0.16 to 0.30 respectively. The values are lower than the recommended safe values

Natural Radioactivity, Radon Exhalation Rates and Radiation Doses in the Soil Samples Collected from the Vicinity of Kolaghat Thermal Power Plant, West Bengal, India

653-658Natural radioactivity has been determined by means of a highly efficient thallium-doped sodium iodide detector in soil sample from surface of from vicinage of “Kolaghat Thermal Power Plant” The activity concentration (specific activity) is found to vary from 23.70 ± 3.41 to 33.90 ± 4.33 Bqkg-1 for 226Ra, from 6.67 ± 2.01 to 21.60 ± 2.11 Bqkg-1 for 232Th and that for 40K from 461.01 ± 66.16 to 610.25 ± 80.87 Bqkg-1 with expected value of 29.26 ± 3.50, 4.86 ± 2.03 and 517.53 ± 71.61 Bqkg-1 of Radium-226, Thorium-232 and Potassium-40 correspondingly. The radon exhalation rates were also computed from all samples using the "Sealed Can Technique”. The activity due to radon fluctuates from 47.9 ± 6.2 to 157.6 ± 11.3 Bqm-3 having an arithmetic mean of 89.3 ± 7.9 Bqm-3. The surface exhalation rate and mass exhalation rates were estimated to fluctuate from17.3 ± 2.2 to 56.8 ± 4.1 mBqm-2h-1 with an expectation of 32.1 ± 3.0 mBqm-2h-1 and from 0.6 ± 0.1 to 2.1 ± 0.2 mBqkg-1h-1 averaged out to 1.2 ± 0.1 mBqkg-1h-1respectively. Radiation doses were also calculated in these samples. Indoor and outdoor annual effective doses, Absorbed dose rates, External Hazard index and Indoor inhalation exposure, also known as radon effective dose, was computed and varied from 0.19 to 0.25 mSv y-1, 39.30 to 51.61 nGyh-1, 0.048 to 0.063 mSvy-1, 0.21 to 0.28 and 0.29 to 0.36 and 2.04 to 6.70 μSvy-1 respectively. The values which were obtained in this study are found to be well below the allowed permissible limits, so the soil may be used as building construction material