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The activity concentrations of Th-232, Ra-226, and K-40 in different pumice samples have been determined by high-resolution gamma-ray spectrometry using a 110% HpGe detector. The radium equivalent activities (Ra-eq), external hazard index (H-in), and internal hazard index (H-in) associated with the natural radionuclides and representative level index (I-yr) are calculated to assess the radiation hazard of the natural radioactivity in the pumice samples. The mean values of the measured radioactivity concentrations of Th-232, Ra-226, and K-40 for pumice samples from the region of lakes (ROL) are 232.4 +/- 8.0, 196.9 +/- 7.8, and 1325.8 +/- 20.4Bq kg(-1) and for pumice samples from Cukurova region (CR) 16.3 +/- 4.0, 16.1 +/- 4.9, and 479.7 +/- 170.4Bq kg(-1), respectively. The calculated Ra-eq values vary from 435.9 +/- 12.5 to 883.6 +/- 41.5 Bq kg(-1) with a mean of 630.9 +/- 20.2 Bq kg(-1) for the ROL samples and from 49.7 +/- 3.3 to 101.9 +/- 7.2 Bq kg(-1) with a mean of 76.3 +/- 23.7 Bq kg(-1) for the CR samples. For the ROL samples, Ra-eq are above the limit of 370 Bq kg(-1), equivalent to external gamma dose of 1.5 mSv yr(-1), recommended for the safe use of construction materials by NEA-OECD, while for the CR samples, Ra-eq values are lower than the limit. (c) 2006 Elsevier Ltd. All rights reserved. |
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