International Journal of Engineering Trends and Technology (IJETT) – Volume 8 Number 4 - Feb 2014
Powder Milk Rn222 Exhalation Rate Measurements in Different Kinds Ali K. Alsaedi Department of Physics, College of Science, University of Kufa, Iraq
Abstract— The application of CR-39 SSNTD technique to the determination of radioactive contaminants in different kinds of milk can be very useful. Radon concentrations in animal milk samples collected from different countries were measured using the sealed-can technique based on the CR-39 SSNTDs. The average 222Rn and 226Ra concentrations are found to be 20.20 Bq m-3 and 0.15 Bq kg-1, respectively. The highest radon exhalation rate was found in sample AL-Mudhish, Oman. Keywords— Milk, radon, CR-39, exhalation rate
I. INTRODUCTION
h in an oven to ensure complete moisture removal. Dried samples were pulverized and sifted through a 2 mm sieve. The milk was stored at room temperature for about 90 d before counting to achieve equilibrium for 238U and 232Th with their respective progeny [2]. In the present calibration experiment was used to determine 222Rn gas concentration emanating from a 226Ra source with 3.3 kBq from the International Atomic Energy Agency in a close system. After exposure, the CR39 detector is removed and chemically etched as reported [3-10]. Alpha-particle track measurement per cm2 produced by the decay of 222Rn and its daughters was conducted using an optical microscope (NOVEL, China) of 40x magnification power with USB 2.0 Camera Application V 2.3 software. Radon concentration (CRn) was calculated by [11] Nt CRn ( Bq m3 ) o o , (1) ot
CR-39 used as the detector in the determination of the radioactive contaminants. This detector has a high sensitivity. The CR-39 detectors are used for long-term measurement of radon exhalation rate. Track-etch plastic detector is passive device. 222Rn and their short-lived decay products are primary contributors to the effective dose received by the population due to natural radiation [1]. Radon concentration is determined by measuring the emitted alpha particles that causes damage to the detector surface. Radon levels show important spatial variations on a regional or local scale. The where No = activity concentration for a standard track density, exposure time, and calibration factor are necessary for calculating the radon source (radium), to = exposure time for standard concentration. The aims of this study are to source, ρo = track density for a standard source ascertain the radon exhalation rate in milk samples. (track cm-2), ρ = track density for sample (track cmThis method could be be used to control the quality 2), and t = exposure time of the sample. The effective radium content of the milk samples of the milk consumed in Iraq. can be calculated by [12, 13]: II. MATERIALS AND METHODS hA 1 )( ) (2) A In this study, CR-39 detectors were placed at CRa ( Bq kg ) ( kTe M the closed top end of a plastic cup (6 cm x 7.5 cm). where M is the mass of the milk sample in kg, A The radon level was measured using TASTRAKTM _ is the area of a cross section of the cylindrical (m2) track etch detectors with chemical composition of C12H18O7, a density of 1.32 g cm-3, and size 1 cm2 and h is the distance between the detector and the purchased from Track Analysis Systems Ltd., top of the milk sample in m. ρ is the counted track Bristol, UK. The radon level was measured using density, k is the calibration factor of the CR-39 CR-39 detectors in milk samples from different track detector, and Te denotes the effective countries. Milk samples were dried at 100 °C for 3 exposure time.
ISSN: 2231-5381
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International Journal of Engineering Trends and Technology (IJETT) – Volume 8 Number 4 - Feb 2014 Regalac, Belgium
0.00325
0.17±0.03
M11
0.00263
0.13±0.03
0.00384
0.20±0.03
0.00258
0.13±0.03
0.00305
0.16±0.02
M15
Altunsa, Newzeland Lotte nido, Newzeland Al-Farasha, Newzeland Similac gain advance, Ireland Premier, Ireland
0.00374
0.19±0.03
M16
Dielac 2, Vettnam
0.00262
0.13±0.03
M17
Dielac, Vettnam, Oman Fresh, Oman
0.00322
0.16±0.03
0.00327
0.17±0.03
0.00411
0.21±0.02
M20
AL-Mudhish, Oman Amis, Oman
0.00222
0.11±0.03
M21
Nido, UEA
0.00261
0.13±0.03
M22
Five cows, UEA
0.00236
0.12±0.03
0.00298
0.15±0.03
M12 M13 M14
M18 M19
Avg.
±4.76 22.02 ±4.78 17.81 ±4.3 25.97 ±5.19 17.47 ±4.26 20.64 ±4.63 25.31 ±5.13 17.77 ±4.3 21.80 ±4.76 22.11 ±4.79 27.82 ±5.37 15.01 ±3.95 17.66 ±4.28 15.97 ±4.07 20.20 ±4.56
0.033 0.159± 0.033 0.128± 0.030 0.187± 0.036 0.126± 0.030 0.149± 0.032 0.182± 0.036 0.128± 0.030 0.157± 0.033 0.159± 0.033 0.200± 0.038 0.108± 0.027 0.127± 0.030 0.115± 0.028 0.145± 0.032
SC= Sample Code 30
25
-3
20
222
III. RESULTS AND DISCUSSION The calibration factor obtained from the experiments has mean 0.0107 track cm-2 d-1 per (Bq m-3). The 222Rn and 226 Ra concentrations in milk samples are presented in Table 1. The minimum and maximum radon and radium concentrations were found to be 13.46±3.74 Bq m-3 in M3 Sunny baby 2, France and 27.82±5.37 Bq m-3 in B19 AL-Mudhish, Oman as shown in Fig. 1. The present results show that the radon concentration in milk samples is below the limit recommended (International Commission of Radiation Protection) (ICRP). The mass exhalation rates in the collected milks samples are given in Table 1. The radon exhalation rate varied from 0.00199 Bq kg-1 d-1 to 0.00411 Bq kg-1 d-1.
M10
Rn (Bq m )
The exhalation rate was calculated using [14]: CV (3) Ex (e T 1) A(T ) where Ex is the radon exhalation rate (Bq kg-1 d 1 ), C is the measured radon concentration by the CR-39 detector (Bq m-3 d -1), λ is the decay constant of radon (d -1), T is the exposure time (d), V is the volume of the radon chamber (m3), and A is the mass of the sample. The annual effective dose (HE) was calculated [1]: HE (mSv y-1) = C × F × T × D (4) where C is the radon concentration in Bq m-3, F is the 222Rn indoor equilibrium factor (0.4), T is time (8760 h y-1), and D for dose conversion factor (9 x 10 -6 mSv y-1 (Bq m-3)-1 ).
15
TABLE I RN AND 226RA CONCENTRATIONS IN MILK SAMPLES
0.00315
0.16±0.03
M7
Lery 1, France
0.00309
0.16±0.03
M8
Tanoo 1, Belgium
0.00278
0.14±0.03
M9
Biomil 1, Belgium
0.00322
0.16±0.03
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M9 M1 0 M1 1 M1 2 M1 3 M1 4 M1 5 M1 6 M1 7 M1 8 M1 9 M2 0 M2 1 M2 2
0.15±0.03
0.05
0.00 M9 M1 0 M1 1 M1 2 M1 3 M1 4 M1 5 M1 6 M1 7 M1 8 M1 9 M2 0 M2 1 M2 2
0.00292
M6
Lait Celia 1, France Guigoz 2, France
M5
0.10
M8
0.17±0.03
M7 M8
0.00339
M4
M7
0.10±0.03
0.15
M6
0.00199
M3
M5 M6
0.17±0.02
M5
0.00326
0.20
M4
Sunny baby 1, France Sunny baby 2, France Nactalia 1, France
10 M3 M4
M2
HE (mSv y-1) ±St. error 0.114± 0.028 0.159± 0.033 0.097± 0.026 0.165± 0.034 0.142± 0.032 0.154± 0.033 0.151± 0.033 0.136± 0.031 0.157±
M3
0.00233
Rn (Bq m-3) ±St. error 15.80 ±4.05 22.10 ±4.79 13.46 ±3.74 22.96 ±4.88 19.76 ±4.53 21.33 ±4.71 20.96 ±4.66 18.84 ±4.42 21.79
M2
Lailac 1, France
222
M1 M2
M1
Effective radium content (Bq kg-1) ±St. error 0.12±0.03
M1
Ex (Bq kg-1 d-1)
-1
Name/Location
Ra (Bq kg )
SC
226
222
Fig. 1 Average 222Rn and 226Ra concentrations. The green bar represents low concentration, and the red bar represents high concentration.
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International Journal of Engineering Trends and Technology (IJETT) – Volume 8 Number 4 - Feb 2014 IV. CONCLUSIONS
[4]
222
The The Rn concentration in the milk samples varies from 13.46 Bq m-3 to 27.82 Bq m-3 with mean 20.20 Bq m-3. The highest radon exhalation rates are found in sample AL-Mudhish, Oman. The annual effective dose equivalent ranges from 0.097 mSv y-1 to 0.200 mSv y-1, with an average of 0.145 mSv y-1. The values of radium content in milk samples were found to be lower than the permissible value of 370 Bq kg-1 recommended by Organization for Economic Cooperation and Development [15].
[5]
[6]
[7]
[8]
ACKNOWLEDGMENT
The The author is grateful to Dr. Basim A. Almayahi, Department of Environment, College of Science, University of Kufa for assisting me throughout conducting the present research. Financial support was provided by the College of Science, University of Kufa.
[9]
REFERENCES
[12]
[1]
[2]
[3]
UNSCEAR. United Scientific Committee on the Effects of Atomic Radiation, The 2000 Report to the General Assembly with Scientific Annexes. New York: United Nations 2000. Myrick T., Berven B., Haywood F. Determination of concentrations of selected radionuclides in surface soil in the U.S. Health Phys 1983, 45: 631-642. Almayahi, B. A., Tajuddin, A. A., Jaafar, M.S, 2011. In-Situ radon level measurement for a tropical country. Proceedings of International Conference on Chemical, Biological and Environment Sciences (ICCEBS' 2011) in Thailand, 415-417.
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[10]
[11]
[13]
[14] [15]
Almayahi, B. A., Tajuddin, A. A., Jaafar, M.S, 2012. 210Pb, 235U, 137Cs, 40K, and 222Rn concentrations in soil samples after 2010 Thai and Malaysian floods. Advan. Biomed. Engin. 6, 593-598. Almayahi, B. A., Tajuddin, A. A., Jaafar, M.S., 2012. Measurements of alpha emission rates in bones using CR-39 track detector. Proceedings of 2nd International Conference on Ecological, Environmental and Biological Sciences (EEBS'2012), October 13-14, 2012 at Bali (Indonesia). Almayahi, B. A., Tajuddin, A. A., Jaafar, M.S., 2012. Measurements of naturally occurring 210Pb concentration in animals bones of Northern Malaysian Peninsula. Proceedings of International Conference on Agriculture, Chemical and Environmental Sciences (ICACES'2012) October 6-7, 2012 at Dubai (UAE), 189-191. Almayahi, B. A., Tajuddin, A. A., Jaafar, M.S., 2014, Radiobiological long-term accumulation of environmental alpha radioactivity in extracted human teeth and animal bones in Malaysia. Environmental Radioactivity, 129, 140-147. Ali K. Alsaedi, B.A. Almayahi, A.H. Alasadi, 2013, Cement 222Rn and 226Ra concentration measurements in selected samples from different companies. Asian Journal of Natural & Applied Sciences (AJSC), 2, 4, 95-100. Almayahi, B.A., Raad O. Hussein, Hayder H. Hussain, Ali K. Alsaedi, A.H. Alasadi, Azhar S. Ali, (2014). Bricks Rn222 Exhalation Rates in Some Samples from Different Countries. World Applied Sciences 6: 706-709. Almayahi, B.A., Asaad K. Alsaedi, Ali K. Alsaedi, A.H. Alasadi, Azhar S. Ali, Raad. O. Hussein, Hayder. H. Hussain, 2014. Ceramic Rn222 exhalation rates from different countries. International Journal of Scientific and Engineering Research 5, 2162-2164. Mayya, Y. S., Eappen, K. P., Nambi, K. S., 1998. Methodology for mixed field inhalation in monazite areas using a twin-cup dosimeter with three-track detector. Radiat Prot Dosim, 77, 177–184. Mahur AK, Khan MS, Naqvi AH, Prasad R, Azam A (2008). Measurement of effective radium content of sand samples collected from Chhatrapur beach, Orissa, India using track etch technique. Radiat Meas 43, S520–S522 Khan MS, Zubair M, Verma D, Naqvi AH, Azam A, Bhardwaj MK (2011) The study of indoor radon in the urban dwellings using plastic track detectors. Environ Earth Sci 63:279–282. Grasty R. Geophysics 1997, 62: 1379–1385. OECD, 1979. Report by a Group of Experts of the OECD, Nuclear Energy Agency. OECD, Paris, France.
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