Iraqi Journal of Chemical and Petroleum Engineering Vol.17 No.2 (June 2016) 25- 35 ISSN: 1997-4884 Radiological Assessment and Mechanical Separation of NORM Contaminated Soil from Iraqi Oil Fields Yousif M. Zayir * , Nada. S. Ahmedzeki ** , Takrid M. Nafae *** , Wssam Zaidan *** , O.El Samad *** and Rola Bou Khozam *** * Ministry of Science and Technology, Baghdad, Iraq, ** University of Baghdad,Collage of Engineering, Chemical Engineering Dept. Baghdad, Iraq, *** Lebanese Atomic Energy Commission, Lebanon.. Abstract Naturally occurring radioactive materials (NORM) contaminated sites at Al- Rumaila Iraqi oil fields have been characterized as a part of soil remediation project. Activity of radium isotopes in contaminated soil have been determined using gamma spectrometer High Purity Germanium detector (HPGe) and found to be very high for Al-Markezia, Al-Qurainat degassing stations and storage area at Khadhir Almay region. The activity concentration of samples ranges from 6474.11±563.8 Bq/kg to 1232.5±60.9 Bq/kg with mean value of 3853.3 Bq/kg for 226 Ra, 843.59±8.39 Bq/kg to 302.2±9.2 Bq/kg with mean value of 572.9 Bq/kg for 232 Th and 294.31±18.56 Bq/kg to 156.64±18.1 Bq/kg with mean value of 225.5 for 40 K. Six hazard indexs radium equivalent, representative level index, adsorbed dose rate in air, annual effective dose equivalent, external hazard index, and internal hazard indexes were calculated to estimate the potential radiological health risk in soil and dose rate associated with it and found to be high. Screening of contaminated soil was performed to evaluate the feasibility of particle size separation. The fractions obtained varied between 75 µm (200 mesh) to 300µm (48 mesh).The results show that the largest weight percent in fine particle size cut ( -75, -125+75, -250+125) µm is 73.9% and all radium isotopes are concentrated in 37.5µm particle size while small fluctuations are observed in the other particle size cuts. Key Words: NORM, Radium isotopes, radiological assessment, mechanical separation Introduction Radium is the heaviest alkaline earth metal belonging to Group IIA of the periodical table. It has 25 isotopes with mass numbers between 206 and 230, all of them are radioactive. The most abundant among the naturally occurring isotopes are 226 Ra with a half-life of 1620 years from the uranium series ( 238 U), and 228 Ra with a half-life of 5.8 years from thorium series ( 232 Th). These two isotopes of radium are also the most radiotoxic and very significant from a radiological protection viewpoint due to their relatively presence in nature, Iraqi Journal of Chemical and Petroleum Engineering University of Baghdad College of Engineering Radiological Assessment and Mechanical Separation of NORM Contaminated Soil from Iraqi Oil Fields 26 IJCPE Vol.17 No.2 (June 2016) -Available online at: www.iasj.net long half-lives, and high dose conversion factors. In the 1950s radium was identified as a pollutant of the environment, caused by uranium mining and milling in the USA. Other, non-nuclear branches of industry have also been identified as significant sources of environmental pollution due to radium release as– phosphate fertilizer production, oil and gas exploitation, underground mining of different raw materials (heavy sands, coal, gold etc.).[1] Naturally occurring radioactive materials (NORM) containing 232 Th 238 U- series nuclides can be accumulated and concentrated in surface equipment and tubing in the form of sludge and scale as a consequence of chemical and physical processes associated with the oil and gas industry [2]. In addition, produced water (brine water) associated with oil is typically separated from oil and disposed of by one of these methods, like down an injection well or discharged into the environment for evaporation [3]. In some cases, produced water amount is greater than the amount of oil produced. Therefore, it may be considered the largest volume of radioactive waste produced by the oil and gas industry [2]. Most Middle East operating companies dispose their wastes water into unlined pits and lagoons. Subsequently, the projection water is drained to underground leaving radioactive precipitate within the soil that finally required remedial or treatment action in accordance with radiation protection principles. Therefore, the remediation projects to take away and treat contaminated soil have been started in order to reduce the hazard to workers and public. [2,4]. In Iraqi oil field ( Rumaila), produced water is discharged into the environment for evaporation. Uncontrolled disposal of this type of waste could lead to pollute the environmental and, therefore, finally lead to radiation exposure of workers in this field and members of the public. The goal of the present study is the assessment of the radiation exposure of the existing contamination of land areas from oil and gas industry in Iraqi oil fields. Radiological assessment for Al-Markezia and Al-Qurainat degassing stations and, mechanical separation are made to reduce the cost of disposal by reducing the volume of NORM contaminated soil. Experimental Work 1- Mechanical Separation Three different soil samples from Al- Markezia and Al-Qurainat Degassing stations and Khadhir almay region were identified for radiological assessment. These soil samples are mixed and separated for different particle size ((+300), (-300+250), (- 250+125) , (-125+75), (-75)) using the test sieve shaker ( Impact, SV003). The material held on each of the sieves or the fraction of each particle size was separated, collected, weighed, and percentage of each weight fraction was calculated. The analysis was also carried out regarding average size, mass fractions, and cumulative mass fraction. This step was made in laboratories of Radiological and Nuclear Safety Directorate (RNSD) / Al-Tuwaitha site / Ministry of Science and Technology. 2- Sample Preparation The sample preparation depends on type and quantity of samples under investigation. The soil samples were dried and then moved to spatial container. 100 or 200 ml of each soil sample was placed in standard plastic container then was sealed and stored for 3-4 weeks prior to measurement to permit the decay daughter 214 Bi, 214 Pb, Yousif M. Zayir, Nada. S. Ahmedzeki, Takrid M. Nafae, Wssam Zaidan, O.El Samad and Rola Bou Khozam -Available online at: www.iasj.net IJCPE Vol.17 No.2 (June 2016) 27 212 Bi, 212 Pb, 228 Ac to establish an equilibrium with 226 Ra, 228 Ra and 224 Ra and counting by Gamma spectrometer[5]. The analytical measurements were made in the laboratories of the Environmental Radiation Control Department at the Lebanese Atomic Energy Commission (LAEC) in Lebanon. 3- Measurement of Sample Particle Size Radionuclide activity concentration was analyzed using Gamma spectrometer from Canberra equipped with extended range low-level coaxial High Purity Germanium (HPGe) detector with high resolution (2.1 keV at 1332 keV) and 50% relative efficiency was utilized in this study. In order to reduce the background radiation, the detector was surrounded with a 10-cm-thick lead shield and by a 0.5 cm copper layer to attenuate the X- rays emitted by the lead shield. The detector was linked to standard integrated data processor DSA 1000 desktop inspector electronics from Canberra and the spectra were accumulated in 8K MCA. A standard multigamma radioactive source from Isotope Products Laboratories (ISO) used to the energy calibration. This was done by preparation standard sample in the same geometry as the samples to be analyzed, this step occurred once in week or when needed, the efficiency calibration is estimated. Moreover, efficiency curves were corrected for attenuation and absorption. The background spectra were measured regularly under the same conditions used for the sample and applied to correct the calculated sample activities. The linearity and the resolution of the detector were checked using a standard 152 Eu point source. The time counted for each sample ranged between 3 to 48 hr and spectra were analyzed off- line using Genie 2000 software from Canberra Version V3.1.a, including peak search, nuclide identification, activity and uncertainty calculation, and MDA calculation modules.[5] The method allowed to determine NORM nuclides as summarized in table (1) 226 Ra activities was calculated at 186.2 keV after correction for 235 U [7]. If interference of the 186.2 keV photon from 235 U cannot be excluded, 226 Ra activities in the samples were then measured by determining its gamma emitted daughters ( 214 Pb or 214 Bi) after equilibrium[6]. 228 Ra was determined from the gamma line of its daughter 228 Ac at (911.2 keV), as well as 224 Ra was determined from gamma line of its daughter 212 Pb, and 212 Bi at (238.63, and 727.33) respectively because the emanation rate of the 226 Ra progeny 222 Rn from scales and sludges is typically very low, 226 Ra may be measured directly by its γ energy 186.2 keV in all samples with low concentrations of uranium [7]. Table 1, Summary of Gamma spectrometry on NORM counting solids [2] isotope Isotopes heuristics Energy (keV) Gamma Emissions probability (%) 226 Ra 226 Ra 186.2 3.56 214 Pb 351.93 35.6 214 Bi 609.31 45.49 228 Ra 228 Ac 911.2 26.2 224 Ra 212 Pb 238.63 43.6 212 Bi 727.33 6.65 Radiological Assessment and Mechanical Separation of NORM Contaminated Soil from Iraqi Oil Fields 28 IJCPE Vol.17 No.2 (June 2016) -Available online at: www.iasj.net The two radium isotopes identified to be of primary concern are 226 Ra and 228 Ra because of potential carcinogenic impact. Results and Discussion 1- Hazard Assessment for Soil Sample It is reasonable to develop as many as possible identified radiation health hazard indices analysis to obtain effective conclusion on the human health and environment. Six values have been calculated to assess the radiation health hazards associated with the soil samples as described below [8&9]. Calculation of Radium Equivalent Activity The distributions of 226 Ra, 232Th, and 40 K in samples are not uniform therefore, to represent their specific activities by a single quantity to take into calculation the radiation hazards related with them. To define Raeq activity, it can be assumed that 1 Bq/kg of 226 Ra, 0.7 Bq/kg of 232 Th or 13 Bq/kg of 40 K give the same dose of gamma ray. Radium equivalent has been used as radiological index (Raeq) in Bq/kg which is calculated using Eq. (1) [10] … (1) Where : The activity concentrations of 226Ra in Bq/kg : The activity concentrations of 232Th in Bq/kg : The activity concentrations of 40K in Bq/kg Calculation of Representative level index (Iγ) The representative level index (Iγ) is the second hazard index used in this study for the calculation of gamma radiation related with the natural radioactive materials in the soil. It is calculated using Eq. (2). The safety value for this index is [11] … (2) Calculation of air absorbed radiation dose rate Gamma radiation effects are usually expressed in terms of adsorbed dose rate in air. At a height of about 1 meter above the ground surface the external terrestrial absorbed dose rate of γ- radiation in air was calculated for 226 Ra, 232 Th and 40 K radionuclides, using Eq. (3). The conversion factor of 0.462 nGy h -1 /Bq kg -1 for 226 Ra, 0.621 nGy h -1 /Bq kg -1 for 232 Th, and 0.0417 nGy h -1 /Bq kg -1 for 40 K, equilibrium is assumed between 226 Ra and 232 Th series with all their daughter and the effect of 90 Sr, 137 Cs, and 235 U decay series can be neglected because of their small contribution to the whole dose from background. [11] ( ) … (3) Calculation of Annual Effective Dose The annual effective dose equivalent outdoor predictable to be absorbed by the human due to the radioactivity in soil was calculated using Eq. (4). To convert absorbed rate in air to effective dose using a conversion factor of 0.7 Sv Gy -1 , with an outdoor occupancy factor of 20 and 80% for indoor [11]. ( ⁄ ) ( ) … (4) Calculation of External and Internal Hazard Index [10] The external hazard index (Hex) is widely used to reflect to external exposure and can be calculated by Eq. (5): Yousif M. Zayir, Nada. S. Ahmedzeki, Takrid M. Nafae, Wssam Zaidan, O.El Samad and Rola Bou Khozam -Available online at: www.iasj.net IJCPE Vol.17 No.2 (June 2016) 29 … (5) And the internal hazard indexes (Hin) used to reflect to internal exposure to radon and its daughter … (6) In order to keep the radiation hazard to be insignificant the value of external and internal radiation hazard index must be less than unity. The data in Table (2) are summarized of measurements of natural radionuclide ( 226 Ra, 232 Th, and 40 K) concentration in the collected soil samples from Markezia (M1and M2) and Qurainat (Q1) degassing station, and Khidhr-almay (KH1) where mean value of samples (S7 to S11) were taken. The world average concentrations for 226 Ra, 232 Th, and 40 K in soil sample are 35, 30, 400 Bq/kg respectively. Table (2) shows that, The activity concentration of 226 Ra and 232 Th in selected soil of degassing station are higher than the world value reported in [10] and these concentration are more than 150 and 44 times for 226 Ra and 232 Th respectively. The concentration for 40 K is lower as compared with the world figures. The value of radium equivalent activity, representative level index, absorbed gamma radiation dose, annual effective dose equivalent outdoor, internal and external hazard index are shown in Table (3). Radium equivalent is calculated from Eq. (1) values of contaminated samples range from 7593.83Bq/kg (Markezia ) to 1679.93Bq/kg (Qurainat) with mean value 4636.88 Bq/kg which is higher than the safe limit (370 Bq/kg) recommended by Organization for Economic Cooperation and Development (OECD)[8]. The recommended value of annual effective dose equivalent is 1 mSv/year for the personal of the public and 20 mSv/year for the workers in the radiation field. This is fixed by the International Commission on Radiological protection (ICRP). From table (3) it is clear that the absorbed dose rate calculated by Eq. (3) ranges from 3478.59 (Markezia) to 765.36 (Qurainat) nGyhr -1 with an average value of 2121.98 nGyhr -1 . The world wide average annual effective dose is approximately 0.5 mSv. The annual effective dose of these samples is higher than the acceptable value except Q1. The values of internal and external hazard index are higher than unity therefore, according to the report of radiation protection 112; the soil isn't safe and can't be used as a building material without any significant radiological hazard to population [9]. 2- Particle Size Distribution Particle size measurement was made using sieve analysis.After sieving, each particle size cut was collected, weighted and measured. Fig. 1, Histogram presentation of screen analysis Radiological Assessment and Mechanical Separation of NORM Contaminated Soil from Iraqi Oil Fields 30 IJCPE Vol.17 No.2 (June 2016) -Available online at: www.iasj.net The results are shown in Table (4) and Figure (1 and 2), plotted as a histogram, and cumulative distribution. The fractional or acumulative distribution curves are made by assuming the material between two screens to have a particle diameter that is the arithmetic average of the two screen openings. Table 2, the activity concentrations of 226 Ra, 232 Th, and 40 K in Bq/kg measured in contaminated soil Sample No. A.Conc. of 226 Ra Bq/kg A.Conc. of 232 Th Bq/kg A.Conc. of 40 K Bq/kg M1 6474.11±563.8 774.59±9.19 156.64±18.1 M2 4073.91±141.12 843.59±8.39 170.05±13.01 Q1 1232.5±60.9 302.2±9.2 198.5±14.6 KH1 3619.4±12.9 843.3±9.9 294.31±18.56 S7-S11 5508.3±217.6 1363±69.2 315.5±24.5 Table 3, calculated values of hazard assessment Sample No. Radium equ. activity (Bq/kg) Raeq Representative level index (Iγ) Absorbed dose rate D (nGy hr -1 ) Annual effective dose rate mSv AEDE External hazard index Hex Internal hazard index Hin M1 7593.83 51.01 3478.59 4.27 20.52 38.02 M2 5293.34 35.71 2413.11 2.96 14.30 25.31 Q1 1679.93 11.37 765.36 0.94 4.54 7.87 KH1 4847.98 32.76 2208.12 2.71 13.10 22.88 S7-S11 7481.95 50.56 3404.52 4.18 20.22 35.10 Fig. 2, Cumulative distribution curve The results were obtained for five fractions with different mesh size and their weight percent in the samples. The fractions obtained varied between 75 µm (200 mesh) to 300µm (48 mesh). Figures above show that the largest weight percent in fine particle size ( -75, -125+75, -250+125) µm is 73.9% . The average diameter d50 was determined from Fig(2) and was equal to112 µm. The surface mean diameter of soil samples was calculated from Eq. (7) and found to be equal to 48 µm. This value ensures the high contribution of the fines in the soil sample, considering the surface mean in the calculations. Yousif M. Zayir, Nada. S. Ahmedzeki, Takrid M. Nafae, Wssam Zaidan, O.El Samad and Rola Bou Khozam -Available online at: www.iasj.net IJCPE Vol.17 No.2 (June 2016) 31 √ ∑ ∑ ( ) … (7) Radioactivity Distribution with Soil Particle Size Each particle size soil sample was analyzed for the exposure dose rates by portable instrument to select the dealing method. The results are presented in table (5). It can be seen that high values of exposure rate for all samples are observed, and greater than three times of the background (BG) value, therefore, personal protection equipment was used. Furthermore the work area was carefully prepared to reduce the contamination of the area and equipments Table 4, Results of typical screen analysis Sample No. Mesh No. particle size µm Mean particle size Dp (µm) Weight of sample (g) Weight % Cumulative S1 -200 -75 37.5 544.8 22.8 0.228266 S2 -115 + 200 -125 +75 100 543 22.8 0.455778 S3 - 60 + 115 -250 +125 187.5 676.6 28.3 0.739267 S4 - 48 + 60 -300 +250 275 228 9.6 0.834796 S5 48 300 300 394.29 16.5 1 Table 5, Exposure rate measurement for soil samples Sample No. particle size µm Mean particle size µm Exposure rate nSv/hr S1 -75 37.5 677 S2 -125 +75 100 397 S3 -250 +125 187.5 313 S4 -300 +250 275 225 S5 300 300 393 BG 60 Table 6, Activity concentrations for radium isotopes and potassium of contaminated soil for Particle size distribution Sample No. A.Conc. of 226 Ra Bq/kg A.Conc. of 228 Ra Bq/kg A.Conc. of 224 Ra Bq/kg A.Conc. of 40 K Bq/kg 186.2 keV 351.93 keV 609.31 keV 911.2 kev 238.63 keV 727.33 keV 1460 keV S1 14520±279.2 13290±222.8 12850±211 3367±116.5 3935±81.7 4545±75.4 245.5±9 S2 5759±119.2 5398±91.4 5202±86.5 1549±55 1751±36.9 1984±43.6 339.8±20.7 S3 5160±208.9 4694±188.1 4330±174.2 1234±62.2 1503±62.6 1623±66.3 332.8±17.7 S4 7038±289.9 6267±251.5 5714±230.4 1672±85.5 2072±86.6 2336±101 240.9±39 S5 7669±313 6903±276.8 6344±255.5 2007±101.7 2407±100.4 2596±108.7 223±43 Radiological Assessment and Mechanical Separation of NORM Contaminated Soil from Iraqi Oil Fields 32 IJCPE Vol.17 No.2 (June 2016) -Available online at: www.iasj.net After that all these samples were measured by gamma spectrometer techniqe and the results are shown in table (6). 226 Ra, 228 Ra, and 224 Ra activities were determined in different particle size soil samples from the contaminated area in al-Rumaila oil field. The results of samples are presented in table (6) and Fig. (3, 4, and 5). It was observed that all radium isotopes are concentrated in 37.5µm particle size and small fluctuations in other particle size. Furthermore, The activity concentrations of radium isotopes ( 226 Ra, 228 Ra, and 224 Ra) with small particle size is higher than the activity concentration with large particles. For that, determination of radium isotopes distribution with particle size is more important for volume reduction of radioactive waste [12]. Fig. 3, Particle Size distribution with Activity Concentrations for 226 Ra Fig. 4), particle size distribution with activity concentrations for 228 Ra Fig. 5, particle size distribution with activity concentrations for 224 Ra 3- Evaluation of the Homogeneity of the Contaminated Soil To insure that all contaminated soil was completely homogenized the five random samples were taken, as shown in Fig. (6). Fig. 6, Scheme for the Preparation and Homogeneity Test The analytical results of the homogenized contaminated soil sample of 226 Ra, 228 Ra, 224 Ra, and 40 K are shown in table (7) & Figure (7, 8, 9 and 10). The mean value for 226 Ra , 228 Ra , 224 Ra , and 40 K are 6088, 1363.4, 1785.8, and 315.46 Bq/kg with standard deviation as 138.51, 18.28, 30.69, and 32.6 respectively. The results show that the higher standard deviation occurs for 40 K while the standard deviation for 226 Ra, 228 Ra, 224 Ra is approximately the same for that the aggregate may be regarded as Yousif M. Zayir, Nada. S. Ahmedzeki, Takrid M. Nafae, Wssam Zaidan, O.El Samad and Rola Bou Khozam -Available online at: www.iasj.net IJCPE Vol.17 No.2 (June 2016) 33 homogenous because all values were distributed on the mean values. Fig. 7, Representation of homogeneity test results for 226 Ra concentration in contaminated soil Fig. 8, Representation of homogeneity test results for 228 Ra concentration in contaminated soil Fig. 9, Representation of homogeneity test results for 224 Ra concentration in contaminated soil Fig. 10, Representation of homogeneity test results for 40 K concentration in contaminated soil Table 7, Activity concentration for radium isotopes and potassium in homogenized contaminated soil Sample No. A.conc. of 226 Ra Bq/kg A. conc. of 228 Ra Bq/kg A.conc. of 224 Ra Bq/kg A.conc. of 40 K Bq/kg 186.2 keV 351.93 keV 609.31 keV 911.2 keV 238.63 keV 727.33 keV 1460 keV S7 5875±244.3 5213±209.9 4918±198.6 1341±69.2 1655±69.3 1885±84.5 322.3±24.5 S8 6247±253.1 5562±222.8 5110±205.6 1391±70.2 1721±71.7 1864±76.5 322.7±16.5 S9 6141±257.6 5493±220.9 5087±205.7 1368±71.2 1722±72.3 1916±88.7 362.9±29 S10 6048±253.7 5362±215.7 4926±199.2 1360±70.7 1668±70.1 1815±84.6 286.9±25.9 S11 6129±253.8 5488±220.4 5021±202.6 1357±69.8 1713±71.7 1899±84.2 282.5±22.6 Radiological Assessment and Mechanical Separation of NORM Contaminated Soil from Iraqi Oil Fields 34 IJCPE Vol.17 No.2 (June 2016) -Available online at: www.iasj.net Conclusions 1- The activity concentrations of radium isotopes ( 226 Ra, 228 Ra, and 224 Ra) with small particle size are higher than the activity concentration with large particles. 2- The activity concentration of 226 Ra and 232 Th in selected soil of degassing station are higher than the world value reported in [10] and these concentrations are more than 150 and 44 times for 226 Ra and 232 Th respectively. While the concentration for 40 K is lower as compared with the world figures. 3- The largest weight percent in fine particle size ( -75, -125+75, - 250+125) µm is 73.9% . Nomenclature AEDE Annual effective dose rate The activities concentration of 226Ra The activities concentration of 232Th D Absorbed dose rate of γ-radiation in air d50 Mean particle diameter Hex The external hazard index Hin The internal hazard indexes Iγ The representative level index A.conc Activity concentrations IAEA International Atomic Energy Agency KH1 Soil sample from Khidhr-almay region M1,M2 Soil samples from Markezia degassing station MCA Multi channel analyzer MOST Ministry Of Science and Technology NORM Naturally occurring radioactive materials Q1 Soil sample from Qurainat degassing station S1,S2,,S11 Soil samples References 1- IAEA International Atomic Energy Agency, 1990. "The Environmental behaviour of radium". Technical Reports Series No. 310, Volume 1. 2- IAEA International Atomic Energy Agency, 2003. "Extent of Environmental Contamination by Naturally Occurring Radioactive Material (NORM) and Technological Options for Mitigation". Technical Reports Series No. 419, Vienna. 3- Mohammad Saied Al-Masri, Abdul- aziz Aba, 2007. "First proficiency test for the determination of NORM in contaminated soil from the oil field". Accred Qual Assur 12, 249- 256. 4- Othman I., Al-masri M.S., 2004. Disposal strategy for NORM waste generated by the Syrian oil industry. A paper presented at the international symposium on the disposal of low activity waste. 13- 17 December 2004, Cordoba, Spain. 5- Samad O. El., M. Aoun, B. Nsouli, G. khalaf, M. Hamze, 2014. “Investigation of the radiological impact on the coastal environment surrounding a fertilizer plant". Journal of Environmental Radioactivity, Vol. 133, pp. 69-74. 6- OGP International Association of Oil& Gas Producers. 2008. "Guidelines for the management of Naturally Occurring Radioactive Material (NORM) in the oil & gas industry". OGP, Report No.412. 7- Ebaid Y.Y., 2010. "Use of Gamma- Ray spectrometry for uranium isotopic analysis in environmental samples" Rom. Journ. Phys., V 55, Nos. 1-2, P. 69-74, Bucharest. 8- Rahman S.U., Matiullah, Malik F., Rafique M., Anwar J., Ziafat M., Jabbar A., 2011. "Measurement of naturally occurring/fallout radioactive elements and assessment of annual effective dose in soil Yousif M. Zayir, Nada. S. Ahmedzeki, Takrid M. Nafae, Wssam Zaidan, O.El Samad and Rola Bou Khozam -Available online at: www.iasj.net IJCPE Vol.17 No.2 (June 2016) 35 samples collected from four districts of the Punjab Province, Pakistan". J. Radioanal Nucl. Chem., V 287, P 647-655. 9- Rohit M., Surinder S., Kulwant S., Rajendra S., 2007. " 226 Ra, 232 Th and 40 K analysis in soil samples from some areas of Malwa resion, Punjab, India using gamma ray spectrometry". Environ Monit Asses. V 134, P 333-342. 10- UNSCEAR [2000]. Sources and Effects of Ionizing Radiation. United Nations Scientific Committee on the effect of atomic radiation. New York: United Nations. 11- UNSCEAR [1993]. Sources and Effects of Ionizing Radiation. United Nations Scientific Committee on the effect of atomic radiation. New York: United Nations. 12- Othman I., Al-masri M.S., 2002. Characterization of NORM contaminated sites at the Syrian oil-field: sampling, analysis and data management. Conference, February 24-28.