MOJ ISSN: 2379-6294 MOJT

Toxicology
Research Article
Volume 3 Issue 1 - 2017
Radiation Survey of an Area Suspected to be Contaminated by Depleted Uranium Released from Industrial Radiography Camera
Hajo Idriss1,2*, Elsadig Gumaa3, Abbas Yassin1, Hatem Eltayeb1, Sahar Algadi1, Eisa MH4 and Isam Salih1,5
1Sudan Atomic Energy Commission, Sudan
2Committee on Radiation and Environmental Pollution Protection, College of Science, AI Imam Mohammad Ibn Saud Islamic University, Saudi Arabia
3Sudanese Nuclear & Radiological Regulatory Authority, Sudan
4Physics Department, College of Science, Sudan University of Science and Technology, Sudan
5Department of Physics, Taibah University, Saudi Arabia
Received: October 16, 2016 | Published: January 27, 2017
*Corresponding author: Hajo Idriss, Committee on Radiation and Environmental Pollution Protection, College of Science, AI Imam Mohammad Ibn Saud Islamic University, Riyadh, 11642, Saudi Arabia, Email:
Citation: Idriss H, Gumaa E, Yassin A, Eltayeb H, Algadi S, et al. (2017) Radiation Survey of an Area Suspected to be Contaminated by Depleted Uranium Released from Industrial Radiography Camera. MOJ Toxicol 3(1): 00041. DOI: 10.15406/mojt.2017.03.00041

Abstract

This case was undertaken to measure and identify radiation contamination in soil samples consist of waste generated from industrial radiography camera . Another aim of the present work is to raise awareness of the hazards of radiation among the public and worker of industrial radiography testing. Handheld radiation survey meters and gamma spectrometry based on high-purity germanium detectors (HPGe) have been used for radioactivity measurement. The survey has resulted in the detection of 238U, 235U and 137Cs in the samples. The values of 238U and 137Cs lie within the range 7.780-88.665 Bq/kg and 0.720-11.730 Bq/kg with an average value of 33.003 ± 21.023 Bq/kg and 3.719 ± 2.767 Bq/kg respectively. The average value of the 238U in the current investigation was found to be higher than the reported world-wide data35 Bq/kg. 235U was detected in 9 samples out of 18 samples and ranged from 5.23-104.160 with an average value of 23.199 ± 32.072 Bq/kg. On the other hand, depleted uranium (DU) was investigated and found to be in 9 samples out of 18 on the basis of the natural 235U/238U activity ratio that was determined to be 0.046. The presence of depleted uranium could be attributed to the depleted uranium which are used in shielding of 192Ir in industrial radiography cameras. Based on the results, it can be concluded that the waste generated from industrial radiography cameras constitutes a serious source of DU contamination.

Keywords: 238U; 235U; 137Cs; Radiographic cameras and soil

Introduction

Radiological pollution is an existence of undesirable radioactive materials into the environment (air, water, earth) as a result of human activity [1]. Such pollution presents risk due to the radioactive decay of the pollutants, that emit dangerous ionizing radiation [2]. The level of risk is evaluated by the concentration of the pollutants. It is significant to be clear that the contamination gives rise to the radiation hazard [3].The application of radiation technology in the Sudan has been growing rapidly since the beginning of oil extraction, because it has many uses in the petroleum industry (e.g. in well logging pipelines and quality-control tests for welding inspections). Industrial radiographic tests have recently become very popular in the Sudan in different industrial quality-control applications e.g. steel manufacturing, concrete construction etc. Such applications require highly stringent radiation protection programmes in order to protect the workers, the public and the environment due to the inherent health risks of such material. Many radiological pollution instant globally taken places have caused serious injury to workers and the public [4]. Cameras used in industrial radiography are shielded with depleted uranium for gamma ray attenuation, an ideal metal for such a task due to its high atomic number (92). Many workers have observed black waste coming loose from cameras during the cleaning process; however, this has raised no concerns. Over long times in which the industrial radiography cameras have been repeatedly cleaned, a considerable waste has been released and spread out in the soil over a wide area, and contamination monitors have indicated that high radiation background has observed. This work intends to identify the presence of depleted uranium that might be released from the industrial radiography cameras. Finally, this survey will help the radiation worker to conserve the safety and protection against DU.

Materials and Methods

Study area nd samples collection

Surface soil samples were collected from 20 points at a depth of 10 cm covering an area of 1000 m2 using a grab oil-sampler. The radiation survey meters Radiagem 4000 and RADOS-120 were used to identify the area of high radiation level. These dosimeters were previously calibrated at the Secondary Standard Dosimetry Laboratory (SSDL) of the Sudan Atomic Energy Commission. The calibration factor for Radiagem 4000 was 0.89 μSv/h, while that for RADOS-120 was 0.88 μSv/h. The background radiation was measured in three different environments, far away from any artificial source. The samples were collected in plastic bags, transported to the laboratory and stored in plastic bottles for analysis [5].

Radioativity measurement

Radioactvity concentrations in the samples were measured using the gamma-ray spectrometry system equipped with high-purity germanium detectors (HPGe) of 20% relative efficiency and 2 keV relative resolutions. The detector was calibrated in terms of energy and efficiency for 500 ml Marinelli geometry using custom mixed gamma standard with a serial number MW 651 and MW 652 from International Atomic Energy Egncy (IAEA). The samples were counted for 24 h and the spectra were saved in a computer hard disk for further analysis. The analysis of the gamma spectra was carried out using Gamma-200 software package provided by Silena International. The measurement has resulted in identified gamma-emitting radionuclide from 238U, 232Th, 40K and 137Cs The activity concentration of 228U and 232Th were calculated from their progeny photo peaks: 214Bi (609 keV) and 214Pb (352 keV), and 228Ac (911 keV), 208Tl (583 keV) respectively. 235U was determined from the photo-peaks of (143.77 keV) keV. The activity of 40K, and 137Cs was measured directly through their gamma-energies and 662 keV, 1461 respectively, for comperhinsive deitals of samples measurement see refernaces [6,7].

Results and Discussion

Table 1 presents the backround activity concentration of 238U and 137Cs. These measurement were measured before as baseline data for the area monitoring. In the currnt case the survey has resulted in identified gamma-emitting radionuclide from 238U, 235U and 137Cs as shown in Table 1. In these measurements, close observation at individual data site revealed that there are remarkable variations seem in activity concentrations of 238U and 137Cs. The values of 238U lie within the range 7.780-88.665 Bq/kg with an average value of 33.003 ± 21.023 Bq/kg Activity concentration of the anthorpoginc radionuclide 137Cs ranged from 0.720-11.730 Bq/kg with an average value of 3.719 ± 2.767 Bq/kg as shown in as shown in Table 1. It has been reported that the activity concentaration of 238U in the studied area before contamination ranged from 14.242 ± 4.919 Bq/kg with an average value of 14.242 ± 4.919 Bq/kg as shown in Table2. The Significant concentrations of 238U and 137Cs indicates the presence of contamination. The world average value for 238U in surface soils were 35 Bq/kg. Which means that the average value of 238U in this study is much higher than the reported world-wide data [8]. Upon comparing the results of 137Cs with global data it was found that the obtained values of 137Cs after contamination are far below the reported range investigated by many researcher around the world [9-11]. However, the range of 137Cs concentrations observed in this study is significantly high relative to similar data reported from Libya 0.9 - 1.7 Bq/kg [12]. 235U was detected in 9 samples out of 18 samples and ranged from 5.23 - 104.160 with an average value of 23.199 ± 32.072 Bq/kg.Moreover , depleted uranium (DU) was investigated on the basis of the natural 235U/238U activity ratio that was determined to be 0.046 . Only if the obtained ratio is higher than the given value can the presence of DU be recorded [6-13]. DU was detected at 9 ut of 18 samples see Table 1. The presence of depleted uranium coud be attrabited to the depeletd uranium which are used in shielding of 192Ir in industrial radiography cameras. Of course, DU has had a wide range of peaceful applications, such as the provision of radiation shielding for medical sources, industrial radiography cameras, or as counter weights in airplanes [14]. Contamination of soil with DU has increased public health concerns due to the chemical toxicity of DU at elevated dosages [15]. Inhalation of DU aerosols are recognized as a distinct human health hazard and have been suggested to be responsible in part for illnesses of populations that may exposed [16]. Thefore DU was removed from contaminated area using decontamination equipment, and transportation to a radioactive waste management facility for conditioning. The main problem associated with radioactive waste is the fact that it cannot be degraded or treated chemically or biologically. Therefore, the only options are to contain the waste by storing it in tightly closed containers shielded with radiation-protective materials such as lead [16]. For the more safety preventive measures were carried out to ensure that background radiation levels do not exceed the permissible limits .

Samples

238U

137Cs

235U

235U/238U

1

66.715

6.9

44.92

0.673

2

23.36

2.47

Not detected

Not detected

3

40.135

2.96

Not detected

Not detected

4

30.95

4.6

Not detected

Not detected

5

63.28

2.29

Not detected

Not detected

6

29.91

3.26

Not detected

Not detected

7

16.48

4.65

5.23

0.317

8

29.68

3.39

Not detected

Not detected

9

33.86

3.15

Not detected

Not detected

10

40.3

1.6

Not detected

Not detected

11

22.82

3.13

49.11

2.152

12

23.2

2.63

Not detected

Not detected

13

11.81

2.37

25.76

2.181

14

11.81

3.1

54.91

4.649

15

88.665

8

104.16

1.175

16

31.72

11.73

82.4

2.598

17

21.575

Not detected

32.4

1.502

18

7.78

0.72

18.7

2.404

Min

7.78

0.72

5.23

-

Max

88.665

11.73

104.16

-

Average

33.003

3.719

23.199

-

Std

21.023

2.767

32.072

-

Table 1: The average concentrations with associated standard deviations of 238U, 235U, 235U/ 238U and 137Cs in soil samples contaminated with waste from industrial radiography camera.

Location

238U

137Cs

1

23.91

2.04

2

8.9

< 0.720

3

14.24

< 0.720

4

11.496

< 0.720

5

21.72

< 0.720

6

10.91

< 0.720

7

10.92

< 0.720

8

11.13

< 0.720

9

14.26

< 0.720

10

14.93

< 0.720

Min

8.9

-

Maximum

23.91

-

Average

14.242

-

Std

4.919

-

Table 2: The background activity concentration around the industrial radiography unit before waste from industrial radiographic camera.

Conclusion

From the measurements of radionuclide activity concentrations in soils from aera contaminated by the waste from industrial radiographic camira , the external radiation exposure from the ground has been calculated. To sum up, the following conclusions canbe drawn:

  1. The waste generated by industrial radiography camera constitute a serious source for public and worker exposure to depleted uranium.
  2. The average value of 238U in this study is higher than the reported world-wide data (UNSCEAR) which is 35 Bq/kg.
  3. Depleted uranium was detected at 9 location base on 235U/238U.
  4. Legislation making radiation monitoring of maintenance of industrial radiography in the country mandatory in order to protect workers and the public from the dangers posed by DU contamination.

References

  1. United Nations Scientific Committee on the Effects of Atomic Radiation (2008) Sources and effects of ionizing radiation. Reports to general assembly, United Nations, New York, USA, pp. 221-463.
  2. Tae Ho Woo (2016) Nanoscopic designs of radiological protection in environmental scale for the Fukushima nuclear accident: Strategy by dispersion, dissolution, and filtration. Annals of Nuclear Energy 87: 569-574.
  3. Ravisankar R, Chandramohan J, Chandrasekaran A, Prince Prakash Jebakumar J, et al. (2015) Assessments of radioactivity concentration of natural radionuclides and radiological hazard indices in sediment samples from the East coast of Tamilnadu, India with statistical approach. Mar Pollut Bull 97(1-2): 419-430.
  4. Hajo Idriss, Isam S, Elsadig G, Abbas Yassin EH, Yousif, et al. (2012) Radiation survey of aircraft and heavy machinery scrap. Appl Radiat Isot 70(12): 2686-2688.
  5. Hajo Idriss, Isam Salih, Abdulaziz S, Alaamer, Eisac MH, et al. (2014) Investigation of radioactivity concentration in spent technetium generators. Radiation Physics and Chemistry 97: 346-348.
  6. Vukanac, Novkovic D, Kandic A, Djurasevic M, Milosevic Z (2009) A simple method for determination of natural and depleted uranium in surface soil samples Applied Radiation and Isotopes 68(7-8): 1433-1434.
  7. Ramebäck H, Vesterlunda A, Tovedal A, Nygren U, Wallberg L, et al. (2010) The jackknife as an approach for uncertainty assessment in gammaspectrometric measurements of uranium isotope ratios. Nuclear Instruments and Methods in Physics Research 268(16): 2535-2538.
  8. (2011) United Nations Scientific Committee on the Effects of Atomic Radiation. Effects and risks ofionizing radiation. Report to the General Assembly with Annexes 2: 47-205.
  9. Vukotic P, Borisov G, Kuzmic V, Antovic N, Dapcevic S, et al. (1998) Radioactivity on the Montenegrin Coast, Yugoslavia. J Radioanal Nucl Chem 235(1): 151-157.
  10. Alaamer AS (2012) Characterization of 137Cs in Riyadh Saudi Arabia Soil Samples, World Journal of Nuclear Science and Technology 2(4): 2161-6795.
  11. Thabayneh K, Jazzar M (2012) Natural Radioactivity Levels and Estimation of Radiation Exposure in Environmental Soil Samples from Tulkarem Province-Palestine. Open Journal of Soil Science 2(1): 7-16.
  12. Shenber MA (2001) Fallout 137Cs in Soils from North Western Libya. J Environ Radioact 250(1): 193-194.
  13. Jia G, Belli M, Sansone U, Rosamilia S, Gaudino S (2006) Concentration and characteristics of depleted uranium in biological and water samples collected in Bosnia and Herzegovina. J Environ Radioact 89(2): 172-187.
  14. (2009) IAEA Nuclear Energy Series, Locating and characterizing disused sealed radioactive sources in historical waste Austria NW-T-1.17 1-51.
  15. (2001) World Health Organization (WHO), Depleted uranium sources, exposure and health effects. Geneva 1-4.
  16. Choy C, Korfiatis G, Meng X (2006) Removal of depleted uranium from contaminated soils. J Hazard Mater 136(1): 53-60.
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