الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 119 |  |  |
| | | from | 119 | | |
Abstract
Naturally Occurring Radioactive Materials (NORM) have been identified to be found in the atmosphere and in the terrestrial origins, and they contribute greatly to the radiation exposure of mankind either by living around such materials where NORM is contained or through using them in the different production processes. It has been reported in many publications that cement contains NORM. Hence with the fact that there is little awareness and information on NORM levels in Uganda, it was therefore necessary that the study is carried out. It is worth noting that this work represents the first of such studies in Uganda especially that there is a high increase in the use of cement as a construction material in the country. The aim of this research therefore was to assess the levels of naturally occurring radioactive materials (NORM) in Portland cement (CEM IV B (P) 32.5N) produced in Tororo and Hima Grinding cement industries in Uganda. Raw materials for Portland cement in these factories and the environmental soils around Tororo cement factory and some associated radiological hazards and risks were assessed. Gamma spectrometry was performed using High Pure Germanium (HPGe) N and P-type detectors to analyze the U/Th series and K-40 in the raw materials, cement products as well as the soils collected around Tororo cement factory. Results of the study were compared to the typical world average values. The measured mean activity concentrations for 238U, 232 Th and 40K were; 50.34±1.86, 38.01±1.48 and 331.59±13.19 Bq/kg respectively for the Portland cement raw materials, 31.15±1.49, 20.83±1.02 and 267.60 ± 8.65 Bq/kg respectively for the Portland cement products and 63.22 ± 2.13, 142.92 ± 4.43 and 180.71±6.18 Bq/kg respectively for the soil samples. The respective outdoor annual effective dose rates were found to be 0.07, 0.04 and 0.15 mSv/y. These were found to be within the world average of 0.07 mSv/y according to the UNSCEAR, 2000 report except for the environmental soils which were twice this value. Thus, the results for Portland cement and its raw materials indicated an insignificant exposure of the public and the workers from NORM in these materials while a significant exposure as a result of the environmental soils. The Radium equivalent activity (Raeq) as well as other measures like gamma and alpha indices were also carried out and the results were much comparable to the world averages with exception of the environmental soils around Tororo cement factory which exhibited higher values of about twice the permissible limits for most of the parameters apart from the Raeq which value was 281.51 Bq/kg which is less than the recommended limit of 370 Bq/kg. Therefore, the results of the cement raw materials and the Portland cement exhibited a low probability of radiological hazards and risks making it safe if used as construction materials. However, there was an observed high radiological risk associated with the environmental soils. Hence, it is important that adequate regulatory controls are put in place by the relevant Ugandan national authorities on the use of these soils as building materials, agricultural or industrial activities. The results from the study will be importantly added to the country database and used as a benchmark in the finalization of the draft of the National Regulations on NORM. It is recommended to conduct further studies on all cement raw materials and products in Uganda