The huge volume of Naturally Occurring Radioactive Materials (NORM) wastes produced annually by the oil and gas industry in Libya deserves the attention of the national environmental protection authority, radioactive waste management and regulatory bodies. An investigation was carried out to find out the concentration of (NORMs) in evaporation ponds sludge in south eastern oilfield (A/100) of Libya. Twenty soil samples were collected from five evaporation ponds sludge. Activity concentrations of 226Ra, 232Th and 40K in soil generated during oil production operations were determined using a gamma spectroscopy system based on High Purity Germanium (HPGe) detector. Concentrations ranged from 83 to 1000 Bq kg–1 for 226Ra, 59 to 315 Bq kg–1 for 232Th and 109 to 304 Bq kg–1 for 40K. To evaluate the radiological effects, radium equivalent activity and external hazard are calculated. The magnitude of these results demonstrates the need of screening oil residues for their radionuclide content in order to decide about possibility of minimize the environmental impact of NORM and their final disposal. Disposal of NORM waste has to be in accordance with national regulations, environmental policy and international agreements and conventions. The researchers recommend limits for clearance and disposal, based on best international practice. arabic 18 English 82
Usama Elghawi (1-2021)

There are three main aims that make this study particularly important and interesting to radiometric studies. Firstly, it will provides information on the concentration composition of natural and the associated man-made radioactivity of imported dental porcelain materials to be used by most dental laboratories in Great Jamahiriya. Since these materials do not pass radiation inspection tests before their entry or use and there is a large variety of supply source of these dental materials to be used for all dental works on Libyan patients, anomalies can be identified easily. Secondly, the analysis of selective elemental abundance (U, Th, and K ) and dose rate calculations may be used to calculate effective dose rates to dental laboratory technicians and also to the patient who will be using these specific materials. This research project will provide the first results of such measurements and the corresponding average annual effective dose rates equivalent to the patients using these materials and also to the dental technician and doctors work in the various dental laboratories that make use of these materials in their daily work. A total number of 30 dental powder samples were collected from a number of dental laboratories around Tripoli area will be analyzed. In this research project, the results from this preliminary survey regarding Th, U and K elemental concentrations in a wide variety of dental materials by means of high-resolution X-ray spectrometry will be presented. Further results from these investigations concerning activity concentrations and the associated dose rates, effective dose and the committed dose due to the use of these materials are going to be calculated and compared with other published data elsewhereandrecommendationoftheirusewillbederivedaccordingly. arabic 10 English 74
Karima Mohamed Ali Elmasri, Nouri A. Droughi(9-2010)

Abstract: In this study, a three dimensional computer code based on the so called SIMPLE algorithm (which stands for Semi-Implicit Method for Pressure-Linked Equations) developed by McGill University-Montréal-Canada is used for the numerical solution of a laminar fluid flow and heat transfer of impinging four jets in the presence of crossflow with constant temperature boundary condition on the impingement surface. The governing equations solved by the computer code are the continuity equation, three components of the momentum equation and the energy equation. The finite volume method is adopted for the discretisation of the governing equation. In the computer program, the finite difference equations are solved via the primitive pressure-velocity approach where the hybrid difference scheme, which is a combination of the central and upwind differences, is used to represent the convective and diffusive fluxes over the control volume surfaces. The results obtained show that in general, for multiple jets, the induced and imposed crossflow have significant effects on both the flow and temperature fields near the impingement surface. A strong crossflow deflects the jet and prevents it from impinging on the surface resulting in lower heat transfer rates and hence lower temperatures difference.The results also show that reducing the jet separation distances causes an increase of the temperature of the flow, and hence better cooling of impingement surface.
إبتسام عمارة (2008)