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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Page 204
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
ISSN: 2231-5381
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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