Ijctt v8p137

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 m3 )  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]

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