MEASUREMENTS AND ANALYSIS OF LOW LEVEL NATURAL RADIOACTIVITY IN BUHDING MA1ERIAIS AND EVALUATION OF ITS ENVIRONMENTAL IMPACT

Abstract

Eighty nine samples of raw materials are collected from 49 quarries and 7 commercial companies which cover more than 95% of needs of the Egyptian towns in Cairo region and eighty eight samples of building products are collected from 60 of the largest Egyptian factories which provide more than 95% of all the building products used in this region. The concentration of the natt.nal radionuclides are measured in all the building materials (raw and industrial) used·in urban buildings in Cairo region in Egypt by Gamma Spectroscopy (GS) and Laser Fluorimetry (LF). The specific radioactivity of 226Ra (of 238U) and 232Th for all samples are determined

using a high resolution gamma-ray spectrometer based on HpGe-detector. In raw building materials (except granite), the values varies from 0.4-188 Bq.kg- 1 dry weight for2.0-18.5 Bq.kg-1 dry weight for 226Ra and 0.1-11.9 Bq.kg-1 dry weight for 132Th. For granite the values range between 806-1315 Bq.kg·1.dry weight for9.1-79.3 Bq.kg- 1 dry weight for 226Ra and

12.2-75.7 Bq.kg-1 dry weight for 232Th. In industrial building materials, the values range between 2.9-680 Bq.kg-1 dry weight for6.8-150 Bq.kg- 1 dry weight for 226Ra and 2.1-53.7 Bq.kg-1

dry weight for 132Th.

For comparison, the uranium concentrations in 80 samples of the raw and industrial building materials are determined using a uranium analyzer. The uranium concentrations for raw building materials range between 0.1-1.8 ppm (1.7-21.7 Bq.kg-1 dry weight), except in granite samples; it ranges between 0.4-7.8 ppm (4.4-96.3 Bq.kg-1 dry weight); while for industrial building materials, the uranium concentrations range between 0.5-3.4 ppm (5.6-42.1 Bq.kg-1 dry weight). The data obtained by the two techniques are in good agreement within the experimental error for most of the samples. The radiation hazard of the total natt.nal radioactivity in the studied samples are estimated by different approaches. First, the radium equivalent activity is calculated for all the samples. It ranges between 2.7-36.6 Bq.kg-1 dry weight in the samples of raw materials except in granite, it ranges between 97.9-241 Bq.kg-1 dry weight; while in the samples of industrial building materials, the values range between 13.0-180 Bq.kg·1 dry weight. Second, the e>.temal hazard index x reflecting the e>.ternal radiation level is calculated. The obtained values are less