Measurements of Radon Concentrations and Dose Assessments in Physics Department-Science College-Al-Mustansiriyah University, Baghdad, Iraq

Abstract

Measurements of radon gas concentrations with their progeny and the annual effective dose indoor the building of Al-Mustansiriyah University College of Science-Physics Department have been carried out by using time-integrated passive radon dosimeters solid state nuclear track detector CR-39 technique. The detectors with 1cm x1cm have been distributed over 70 places and suspended for sitting (1m) and standing (1.75m) positions in each location under study. The dosimetric measurements are made over a period of 90 days from 30 January 2014 to 30 April 2014. The calibration process has been done using radium-226 source with known activity radiation. It has found that the indoor radon gas concentrations varing from 37.488±6.123Bg/m3 to 58.670±7.660Bg/m3 with an average value 51.398±7.156Bg/m3 at 1m , and varing from 35.964±5.997Bg/m3 to 56.994±7.549Bg/m3 with an average value 47.057±6.847Bg/m3 at 1.75m which are within the worldwide limits 148Bg/m3 (EPA, 2003) and 200-300Bg/m3 (ICRP, 2009). The annual effective dose of the inhalation exposure to radon gas has been estimated and this vary from 0.394mSv/y to 0.617mSv/y with an average value 0.540mSv/y at 1m, and varing from 0.378mSv/y to 0.599mSv/y with an average value 0.495mSv/y at 1.75m which are within the worldwide permissible limist 3-10mSv/y (ICRP, 1993). The potential alpha energy concentration found to vary from 4.053mWL to 6.343mWL with an average value 5.557mWL at 1m and vary from 3.888mWL to 6.162mWL with an average value 5.087mWL at 1.75m which are less than the recommended value 53.33mWL (UNSCEAR, 1993). The lung cancer cases per million person per year vary from 7.093 to 11.101 per million person per year with an average value 9.725 per million person per year at 1m and vary from 6.805 to 10.784 per million person per year with an average value 8.904 per million person per year which are less than the recommended range 170-230 per million person per year (ICRP, 1993). The number of decays per-minute using swabs measurements technique have been used for selected units within two swabs from building materials walls for each unite, with area of 100cm2 using Ludlum 3030, the average of three swabs measurements have been calculated. Hence, the effectiveness of emitted alpha particles from the walls has been calculated to be varied from 0.00000 to 0.02222Bq/cm2 with an average value 0.01169Bq/cm2 at 1m and 0.01015Bq/cm2 at 1.75m respectevily which are within the permissible limit 0.04Bq/cm2 (Danial, 2010).