الفهرس يوجد فقط 14 صفحة متاحة للعرض العام
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المستخلص
The principal aim of this thesis is to investigate the radiological hazard for cement samples and measure the heavy elements and toxic substances in them. Using Þ spectrometry, the concentration of natural radionuclides 238U, 232Th and 40K has been determined in cement and its raw materials which are utilized as construction materials in Egypt. Twenty three samples of raw materials and final products utilized in the cement factories were collected for study. Thirteen samples were obtained from (Limestone, Clay, Slag, Clinker, gypsum) which represent the raw materials utilized in cement industry and ten samples of final products of commercial cement were obtained from (Portland, El-Mohands and White cement). The activity concentration of 238U, 232Th and 40K in raw materials were observed to be ranged from (56.32 to 615.59) Bq/kg, (11.47 to 77.05) Bq/kg and (68.36 to 948.07) Bq/kg with mean value 134.07, 35.97 and 403.48 Bq/kg for 238U, 232 40 238 232 40 Th and K, respectively. The activity concentration of U, Th and K in final products were observed to be ranged from (62.93 to 234.73 Bq/kg), (20.10 to 38.07 Bq/kg) and (200.53 to 306.58 Bq/kg) with mean value 93.49,29.64 and 257.90 Bq/kg for 238U, 232Th and 40K, respectively. The permissible activity levels of building materials are (50, 50 and 500) Bq/kg for 226Ra, 232Th and 40K, respectively [NEA-OECD, 1979 and UNSCEAR, 1993]. All concentration values of 238U in raw materials and final products are higher than recommended value. The concentration values of 232Th in raw materials and final products are lower than recommended value except sample S1, S3, S8, S10 and S13. The concentration values of 40K in raw materials and final products are lower than recommended value except samples S3, S8 and S13. The results of concentration levels are compared with other measurements from different parts of the world