Natural Radionuclide Contents in Raw Materials and the Aggregate Finished Product from Dangote Cement Plc, Obajana, Kogi State, North Central Nigeria

摘要

Assessment of gamma ray activity in raw materials and the end product in Dangote Cement from Dangote Cement Plc, Obajana and Kogi State has been investigated in this study. Gamma ray spectrometry that possesses scintillation detector was used to analyze the samples collected from the company. Samples collected as raw materials are limestone, clay, gypsum and laterite and cement as finished product. The ~(40)K, ~(238)U, ~(232)Th activity concentration were detected. The concentration of ~(40)K range from 4649+-366 to 0+-65 Bq/Kg with highest value in limestone and lowest in laterite. The ~(238)U concentration is highest in gypsum range from 696+-233 to 41+-27 Bq/Kg in laterite. ~(232)Th activity is below detectable limit in all the raw materials but it has activity concentration of 40+-26 Bq/Kg in the finished product which may be traceable to the fact that some finished additives are present which are not in the basic raw materials of this cement under investigation. It is concluded that the natural radionuclide measured for ~(40)K, ~(238)U and ~(232)Th has mean activities of 2189.75+-219.5, 331.25+-132.25 and 0+-31 Bq/Kg respectively, while its corresponding mean absorbed dose rate in air at 1 m above the ground was calculated to be 235.61 nGy/h or 2.064 mSv/y and the aggregate finished product (cement) has absorbed dose rate of 342.22 nGy/h and an effective dose equivalent of 2.998 mSv/y. The calculated absorbed doses in nGy/h and mSv/y shows that Dangote cement under consideration has higher activities of the isotopes than the permissible level suggested by ICRP (80 nGy/h or 0.7 mSv/y)