Radiological significance of cement used in building construction in Turkey

The activity concentration of (226)Ra, (232)Th and (40)K in seven cement types from different factories and grinding plants were measured using a gamma ray spectrometry with HPGe detector. The average activity concentrations observed in the studied cement samples (all from 141 samples) were 40.0 +/- 27.1, 28.0 +/- 20.9 and 248.3 +/- 95.0 Bq kg(-1) for (226)Ra, (232)Th and (40)K, respectively. The radium equivalent activity (Ra(eq)), the representative level index, the indoor absorbed dose rate and the corresponding annual effective dose were estimated for the potential radiological hazard of the cement. The Ra(eq) values were compared with the corresponding values for cement of different countries. The mean indoor absorbed dose rate (87.4 +/- 48.5 nGy h(-1)) is slightly higher than the population-weighted average of 84 nGy h(-1), whereas the corresponding effective dose rate (0.4 +/- 0.2 mSv y(-1)) is lower than the dose criterion of 1 mSv y(-1). The obtained results indicate no significant radiological hazards arise from using Turkish cement in building construction.     

Radiological assessment of Abu-Tartur phosphate, Western Desert Egypt

The contents of natural radionuclides (²²⁶Ra, ²³²Th and ⁴⁰K)were measured in sedimentary phosphate rock samples (Abu-Tarturphosphate, Western Desert Egypt) by using gamma spectrometry(NaI (Tl) 3"x 3"). Phosphate and environmental samples werecollected from Abu-Tartur phosphate mine and the surroundingregion. The results are discussed and compared with the levelsin phosphate rocks from different countries. The activitiesof ²²⁶Ra, ²³²Th series and ⁴⁰K are between (14.9 ± 0.8and 302.4 ± 15.2), (2.6 ± 1.0 and 154.9 ±7.8) and (10.0 ± 0.5 and 368.4 ± 18.4) Bq kg^–1,respectively. The Abu-Tartur phosphate deposit was found tohave lower activity than many others exploited phosphate sedimentarydeposits, with its average total annual dose being only 114.6µSv y^–1. This value is about 11.46% of the 1.0 mSvy^–1 recommended by the International Commission on RadiologicalProtection (ICRP-60, 1990) as the maximum annual dose to membersof the public.     

Sorption profile of Cd(II) ions onto beach sand from aqueous solutions

Sorption of traces of Cd(II) ions onto beach sand is investigated as a function of nature and concentration of electrolyte (10(-4) to 10(-2)M nitric, hydrochloric and perchloric acids, pH 2-10 buffers and deionized water), shaking time 5-40min, shaking speed 50-200strokes/min, dosage of sand (50-1000mg/15cm(3)), concentration of sorbate (1.04x10(-6) to 1.9x10(-4)M) and temperature (293-323K). Maximum sorption of Cd(II) ions (approximately 66%) is achieved from deionized water using 300mg/15cm(3) sand in 20min. The data are successfully tested by Langmuir, Freundlich and Dubinin-Redushkevich (D-R) sorption isotherms. The values for characteristic Langmuir constants Q=13.31+/-0.20micromol/g and of b=(6.56+/-0.53)x10(3)dm(3)/mol, Freundlich constants A=2.23+/-1.16mmol/g and 1/n=0.70+/-0.05 of (D-R) constants beta=-0.005068+/-0.000328kJ(2)/mol(2), X(m)=46.91+/-11.91micromol/g and energy E=9.92+/-0.32kJ/mol have been estimated. Kinetics of sorption has been studied by applying Morris-Weber, Richenberg and Lagergren equations. The sorption follows first order rate equation resulting 0.182+/-0.004min(-1) The thermodynamic parameters DeltaH=32.09+/-2.92kJ/mol, DeltaS=111.0+/-9.5J/molK and DeltaG=-1.68+/-0.02kJ/mol are evaluated. The influence of common ions on the sorption of Cd(II) ions is also examined. Some common ions reduce the sorption while most of the ions have very little effect. It can be concluded that beach sand may be used as an alternative for the expensive synthetic sorbents.     

Measurement of natural radioactivity in beach sands from Rizhao bathing beach, China

The natural radioactivity of (226)Ra, (232)Th and (40)K was determined for beach sand samples collected from Rizhao bathing beach, China, using gamma ray spectrometry. The measured activity in beach sand ranges from 7.6 to 17.2, 7.8 to 25.1 and 883.4 to 1313.6 Bq kg(-1) for (226)Ra, (232)Th and (40)K with mean values of 12.0, 15.2 and 1079.2 Bq kg(-1), respectively. The activity concentrations of (226)Ra and (232)Th in beach sands are lower, while (40)K is higher than the world average. The radium equivalent activity in all beach sand samples is lower than the safe limit set in the OECD report (370 Bq kg(-1)). The values of the external hazard index are less than unity. The mean outdoor air absorbed dose rate is 59.8 nGy h(-1) and the corresponding outdoor effective dose rate is 0.073 mSv y(-1).     

Radiological significance of building bricks in Pakistan

Baked clay bricks samples were collected from both urban and rural areas of the North West Frontier Province of Pakistan and natural radioactivity due to 40K, 226Ra and 232Th has been measured in these samples. The specific absorbed dose rates due to natural radioactivity emanating from the walls, floors and ceilings of the typical model rooms made of these building bricks have been calculated applying the mesh size adaptive volume integral methodology. The occupancy factor, representing the weighted average of all the population in the country, was taken to be 0.3 in this study. The values of estimated annual effective dose rates for whole body were found to be 0.38 and 0.35 mSv.y(-1) for the two types of model rooms. These values are smaller than those predicted by UNSCEAR for normal background areas. Thus the building bricks analysed in this study do not pose any significant health problem to the population.     

Strength of reed from Egypt

A growing need for building materials and an increasing demand for the analytical calculation of structures mean that data are required about materials which were traditionally used on an empirical basis. This is true for Egyptian reed, and tests are reported on its uniaxial tensile and compressive strength, and its static and impact bending strength.     

Characterization of natural sand proppant used in hydraulic fracturing fluids

Natural sand was the first material introduced as a proppant to hydraulic fracturing operations to keep induced rock fractures both open and conductive. It has remained the most commonly used proppant for this process, since its economic advantages are obvious. In this context, the growth of the unconventional gas industry in Algeria has raised many environmental and economical concerns in terms of local sand valorization for a possible use as proppant agents. This paper deals with the physical analysis of 10 sand samples of two types: quarry sand samples and Aeolian dune sand samples, from different geographic locations in Algeria according to ISO 13503-2 which provides standard testing procedures for evaluating certain physical properties of proppants used in hydraulic fracturing and gravel packing operations. These assessments should enable to compare the physical characteristics of the various tested sands and to select the useful ones to evaluate their interaction with one chemical (SP breaker) in fracturing fluid system by sorption under several operating conditions (temperature, proppant dosage, SP breaker concentration).     

Diffusion tests of mercury through concrete, bentonite-enhanced sand and sand

The transport by diffusion of Hg(II) and Hg(0) through a barrier of concrete or bentonite-enhanced sand was examined under aerobic conditions. Sand was used as a reference system parallel to the two systems. Speciation of mercury was performed with a purge and trap method, where dissolved Hg(0) was purged with nitrogen gas from the sample, through a trap for volatile oxidized mercury species and finally trapped in an oxidative solution. The apparent diffusion coefficient (from Fick's second law of diffusion) for oxidized mercury was 1 x 10(-14)m(2)/s in Standard Portland concrete and 4 x 10(-13)m(2)/s in quartz sand. The diffusion of Hg(0) seemed to be faster than for Hg(II), Hg(0) was however oxidized to Hg(II) under aerobic conditions, and after 45 months only 1-10% of the total mercury concentration was Hg(0).     

Radiological impacts of natural radioactivity from soil in Montenegro

Soil samples from Montenegro were analysed by the HPGe detector with 40 % of relative efficiency, for radioactivity due to (226)Ra, (232)Th and (40)K. The average activity concentrations have been found to be 39.9, 43.5 and 437.6 Bq kg(-1), respectively, i.e. in accordance with those in the other South European countries. In order to evaluate the health hazard, radium equivalent activity, absorbed dose rate, annual effective dose rate, external hazard index, annual gonadal dose equivalent and excess lifetime cancer risk (CR) have been calculated. The excess lifetime CR (× 10(-3)) had a range from 0.12 to 0.79, with an arithmetic mean of 0.27, which is in accordance with the global average. Mean gonadal dose equivalent was higher than the world average, and one location was found with the radium equivalent activity >370 Bq kg(-1), i.e. with the external hazard index higher than unity, which means the radiation hazard is not negligible.     

Economical study for hydrogen production from seawater using renewable energy in Egypt

This study looks into the possibilities of hydrogen production in the north coast and red-sea Zone, Egypt, to conver renewable energy to hydrogen (power to gas). The main purpose is to estimate the power needed for each kg of hydrogen production from seawater using renewable energy and then the quantity of desalinated seawater needed to cover this cost. We will discuss different scenarios; the main two scenarios are photovoltaic (PV) solar with reverse osmosis (RO) desalination and concentrating solar power (CSP) with multi-effect desalination (MED).     

Shape optimization of geotextile tubes for sandy beach protection

This paper describes how to tackle new challenging coastal engineering problems related to beach erosion with a shape optimization approach. The method modifies the shape of the sea bottom in order to reduce beach erosion effects. Global optimization is shown to be necessary as the related functionals have several local minima. We describe the physical model used, the proposed protection devices against beach erosion and real case applications. Copyright © 2007 John Wiley & Sons, Ltd.     

Radon exhalation rate from the soil, sand and brick samples collected from NWFP and FATA, Pakistan

In order to characterise the building materials as an indoor radon source, knowledge of the radon exhalation rate from these materials is very important. In this regard, soil, sand and brick samples were collected from different places of the North West Frontier Province (NWFP) and Federally Administered Tribal Areas (FATA), Pakistan. The samples were processed and placed in plastic containers. NRPB radon dosemeters were installed in it at heights of 25 cm above the surface of the samples and containers were then hermetically sealed. After 40-80 d of exposure to radon, CR-39 detectors were removed from the dosemeter holders and etched in 25% NaOH at 80 degrees C for 16 h. From the measured radon concentration values, (222)Rn exhalation rates were determined. Exhalation rate form soil, sand and brick samples was found to vary from 114 +/- 11 to 416 +/- 9 mBq m(-2) h(-1), 205 +/- 16 to 291 +/- 13 mBq m(-2) h(-1) and 245 +/- 12 to 365 +/- 11 mBq m(-2) h(-1), respectively.     

Natural radionuclides and dose estimation in natural water resources from Elba protective area, Egypt

The concentrations of the natural radionuclides (226)Ra, (232)Th and (40)K in 15 different water samples from Elba protective area, south-eastern desert of Egypt, have been determined using NaI(Tl) detector. Gamma ray spectrometric analysis was performed and the concentrations obtained for each of the radionuclides expressed in Bq l(-1) ranging from 1.6 to 11.1 for (226)Ra, 0.21 to 0.97 for (232)Th and 9.1 to 23 for (40)K. A reasonable correlation was found between (226)Ra, (232)Th concentrations and pH, although no general trend was observed with conductivity and total dissolved solids. The mean effective doses of 0.56 mSv y(-1) for (226)Ra, 0.065 mSv y(-1) for (232)Th and 0.04 mSv y(-1) for (40)K were estimated for the ingestion of these waters by adults.     

浅析牙片机的辐射防护检测

随着牙片机在口腔诊所的普及和应用,其所产生的辐射也逐渐为人们所关注,人们如何认识到看不见摸不着的辐射,从事该职业的人员如何才能最大程度上减少射线的危害。通过在牙片机正常曝光时,分别测量职业人员操作位置辐射剂量和机房周围辐射剂量,将测量数据和辐射防护参考标准中的指导水平进行对比分析,得知无防护时危害性,针对目前牙片机应用现状,应该如何进行防护,才能使职业人员、患者和周围公众受到更少的辐射危害。     

Assessment of metals speciation in sewage sludge and stabilized sludge from different Wastewater Treatment Plants, Greater Cairo, Egypt

The metals speciation in all sludge samples from the different Wastewater Treatment Plants (WWTPs) indicated that, Mn, Ni and Zn were most abundant in the exchangeable, carbonate and Fe/Mn-oxide forms which are the easily assimilable fractions and showed the greatest degree of their mobility, while Cd, Cu, Cr and Fe were major in the organic and sulfide (exhibit some degree of mobility), and the residual form (inert phase) which, corresponds to the part of the metals which cannot be mobilized. Cement kiln dust significantly reduced the availability of metals by chemical modification of their chemical speciation into less available forms.