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Bakr W.F.,National Center for Nuclear Safety and Radiation Control
Journal of Environmental Radioactivity | Year: 2010

The field of radiation protection and corresponding national and international regulations has evolved to ensure safety in the use of radioactive materials. Oil and gas production processing operations have been known to cause naturally occurring radioactive materials (NORMs) to accumulate at elevated concentrations as by-product waste streams. A comprehensive radiological study on the oil refining industry in Egypt was carried out to assess the radiological impact of this industry on the workers. Scales, sludge, water and crude oil samples were collected at each stage of the refining process. The activity concentration of 226Ra, 232Th and 40K were determined using high-resolution gamma spectrometry. The average activity concentrations of the determined isotopes are lower than the IAEA exempt activity levels for NORM isotopes. Different exposure scenarios were studied. The average annual effective dose for workers due to direct exposure to gamma radiation and dust inhalation found to be 0.6μSv and 3.2mSv, respectively. Based on the ALARA principle, the results indicate that special care must be taken during cleaning operations in order to reduce the personnel's exposure due to maintenance as well as to avoid contamination of the environment. © 2009 Elsevier Ltd. Source


Zaki A.A.,Egypt Atomic Energy Authority | El-Zakla T.,Egypt Atomic Energy Authority | Geleel M.A.E.,National Center for Nuclear Safety and Radiation Control
Journal of Membrane Science | Year: 2012

Removal of Cs + and Eu 3+ ions using cellulose acetate (CA) and modified CA was studied. Cellulose acetate was modified using acrylamide (AAm) and polyethylene glycol (PEG). Specifically, CA, CA/AAm, and CA/PEG were used to remove Cs + and Eu 3+ from aqueous waste solutions. The CA-metal and modified CA-metal interactions were studied under different conditions such as concentration of metal ions and temperature in the range 298K-333±1K. Experimental equilibrium sorption data were analyzed using Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm models. These data were better fitted to both Langmuir and D-R isotherms compared to Freundlich model. On the other hand the sorption processes were better represented by pseudo-second order kinetic model. The sorption processes were endothermic with ΔH o values 16.20, 23.55, and 21.70 (kJ/mol) for sorbed Cs + ions onto CA, CA/AAm, CA/PEG, whereas that for sorbed Eu 3+ are 21.79, 23.87 and 75.34 (kJ/mol), respectively. The entropy values ΔS o for Cs + ion sorbed onto CA, CA/AAm, and CA/PEG are 50.72, 80.15, and 77.10 (J/molK), whereas that for the sorbed Eu 3+ ion are 75.0, 87.30 and 256.10 (J/molK) respectively. The activation energy, E a, for Cs + and Eu 3+ ions sorbed onto all studied sorbent materials lies in the range 8.73-26.32 (kJ/mol) and 24.27-78.11 (kJ/mol), respectively. The negative values of Gibbs free energy, ΔG o, confirm the feasibility and the spontaneous nature of both Cs + and Eu 3+ ions sorption removal using CA and AAm and PEG modified CA and indicating that the sorption processes are chemi-sorption mechanisms. The sorption removal capacities of both Cs + and Eu 3+ were in the order CA/PEG>CA/AAm>CA. The batch and dynamic sorption results show that the modified CA/PEG, CA/AAm, and CA membranes can be used to remove Cs + and Eu 3+ ions from wastewater. © 2012. Source


Madani M.,National Center for Radiation Research And Technology | Aly R.A.,National Center for Nuclear Safety and Radiation Control
Materials and Design | Year: 2010

Polymeric materials are widely used as insulation and jacketing materials in wire and cable. When such materials are used for long-term applications, they undergo thermal oxidation aging in the environment. It is necessary to develop an in situ and non-destructive condition monitoring (CM) method to follow the aging of cable materials. The main objective of this work was to investigate polymer composites as potential sensor materials for this purpose. Rubber/carbon black composites with a carbon black loading below the percolation threshold underwent accelerated thermal oxidation aging experiments. The results indicated that the substantial resistivity decreases of the composites could be directly related to the increases in volume fraction of the conductive carbon black, which was mainly caused by the mass loss of polymer matrix and sample shrinkage during the thermal oxidation aging process. Compared to existing CM method based on density change, the electrical resistivity is more explicit regarding its absolute changes throughout the thermal oxidation aging. The change in resistivity spanned over two orders of magnitude, whereas the composite density only increased 5%. The results offer strong evidence that resistivity measurements, which reflect property changes under thermal aging conditions, could represent a very useful and non-destructive CM approach as well as a more sensitive method than density CM approach. Source


Ahmed M.A.,National Center for Nuclear Safety and Radiation Control | Samie S.G.A.,National Center for Nuclear Safety and Radiation Control | El-Maghrabi H.M.,Egyptian Petroleum Research Institute
Environmental Earth Sciences | Year: 2011

Hydrochemical and isotopic researches were conducted in El-Sadat City groundwater system to identify groundwater alteration, recharge, residence time and extent of pollution. The groundwater salinity gradually increases as the groundwater moves from northeastern to southwestern parts of the city. Groundwater generally shows mineralization decreasing with depth, indicating that the possibility of recent water penetration far below the surface is limited. Shallow groundwater has an elevated level of nitrate, which is attributed to anthropogenic sources due to intensive agricultural activity. The limit of high nitrate water may mark the maximum penetration of groundwater from the surface, which is found in depths < 100 m. The northeastern and southwestern industrial areas are highly contaminated by some heavy metals, which may originate from some local industrial effluents. The sewage oxidation ponds seem to show no effect on groundwater; hence, these ponds are not a point source for these heavy metals. Dissolved ions depict five different hydrochemical facies, and stable isotopes define the recharge mechanisms, the origin of groundwater and the hydraulic confinement of deep groundwater. The deep groundwater is untritiated and has long residence times (in the order of thousands of years). Three different hydrochemical groups have been recognized and mapped in El-Sadat City, based on the chemical and isotopic information of the groundwater. These groups have different levels of contamination. The deep groundwater samples are significantly less impacted by surface activities and it appears that these important water resources have very low recharge rates and would, therefore, be severely impacted by overabstraction. The extensive exploitation of groundwater for drinking water supply would shortly be reflected by a gradual decline of the groundwater table in El-Sadat City. Amelioration of groundwater quality requires further management strategies and efforts in the forthcoming years. © 2010 Springer-Verlag. Source


Ramadan A.B.A.,National Center for Nuclear Safety and Radiation Control
Biotechniques for Air Pollution Control - Proceedings of the 3rd International Congress on Biotechniques for Air Pollution Control | Year: 2010

Aerosol samples for PM10 were collected by high volume samplers from September 2006 until July 2008 at three aerosol stations located in greater Cairo area in the north-south direction. Instrumental Neutron Activation Analysis and Atomic Absorption Spectrophotometer techniques were used to measure the concentration of about 35 elements, while a Liquid Chromatography was used to measure ions (SO 4, NO 3 and NH 4). PM10 mass concentrations are generally high through the greater Cairo area. PM10 values obtained for all sampling events at the three monitoring sites are generally high and exceeded the Governmental Egypt's (GOE) Low Number 4 of 1994 limit of 70 μg/m 3 (24-hour average). PM 10 concentrations maximize in spring associated with sand storms during Khamseen conditions and in autumn with longer duration due to trapping of pollutant emissions within a shallow planetary boundary layer. A number of sources including traffic and also biomass/waste burning contribute to the formation of the pollution episodes. The analysis of PM10 samples has shown wide variation in toxic pollutants. The results reveal that the concentrations of several pollutant elements in dust samples from these three sites are highly variable. Some elements showed a dependence on the day of the week, while others did not. The highest mean concentrations of organic carbon (18.6 μg/m 3) and elemental carbon (11.3 μg/m 3) in PM10 were found at Shoubra Kheima among the three sites. The major fractions of sulfate at the three monitoring sites are non-sea-salts sulfate. The monitoring results suggest that control of particulate matter in greater Cairo area may be a difficult problem. Source

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