文章基本信息

标题：Natural Radioactivity in Tanzania Cements and their Raw Materials
作者：Aloyce Isaya Amasi ; Kelvin Mark Mtei ; Ijumba Jasper Nathan 等
期刊名称：Research Journal of Environmental and Earth Sciences
印刷版ISSN：2041-0484
电子版ISSN：2041-0492
出版年度：2014
卷号：6
期号：10
页码：469-474
出版社：Maxwell Science Publications
摘要：This paper presents the study of natural radioactivity in Tanzania Portland cements and their raw materials. Samples collected as raw materials were pozzolan, sandstone, limestone, clay, gypsum and cement as finished products. The natural radioactivity due to the presence of radium ²²⁶Ra, thorium ²³²Th and potassium ⁴⁰K were measured by means of gamma spectrometer coupled with HPGe detector. The mean measured activity concentrations of ²²⁶Ra, thorium ²³²Th and potassium ⁴⁰K in the raw materials range from 2.6 to 93.2, 1.3 to 172.8 and 6.3 to 997 Bq/kg, respectively with higher activity concentrations in pozzolan and lower in gypsum. Activity concentrations of natural radionuclides in raw materials (excluding some materials from Songwe deposits in Mbeya region) are comparative with the worldwide average concentrations of these radionuclides in soil. The average activity concentration of ²²⁶Ra, thorium ²³²Th and potassium ⁴⁰K in the cements are 46, 28 and 228 Bq/kg, respectively. The calculated values of radiological indices are below 60% of the upper recommended values for building materials. The average annual effective dose to an occupant from use of these materials equals to 0.45 mSv. Average activity concentrations of the mentioned radionuclides in Tanzania cements are in the middle of the variability interval of the national averages.
关键词：Annual effective dose ; building materials ; gamma-ray spectrometry ; radium equivalent ; radiation hazard ;