Journal of Environmental Protection, 2010, 1, 10-14
doi:10.4236/jep.2010.11002 Published Online March 2010 (
Copyright © 2010 SciRes JEP
Assessment of Radiological Contamination of Soils Due to
Shipbreaking Using HPGe Digital Gamma-Ray
Spectrometry System
Mohammad Kamal Hossain1, Syed Mohammod
Hossain2, Rezaul Azim1, AKM Moinul Haque Meaze1*
1Department of Physics, University of Chittagong, Chittagong, Bangladesh; 2Institute of Nuclear Science and Technology (INST),
Atomic Energy Research Establishment (AERE), Savar, Dhaka, Bangladesh; *Corresponding Author.
Email: *
Received December 6th, 2009; revised February 1st, 2010; accepted February 3rd, 2010.
A systematic study of the distribution of the Naturally Occurring Radioactive Materials as well as the anthropogenic
radionuclide in the working environment of the Shipbreaking yards of Sitakunda, Chittagong, Bangladesh, has been
carried out with an objective of establishing reliable base line data on the radiation level and hence to measure the
radiation dose expose to the workers and to the inhabitants of the studied area. Fifteen Soil samples have been col-
lected from five different Shipbreaking yards. Three sampling spots in each yard have been selected for having repre-
sentative samples for the assessment of radioactivity releasing from 226Ra (238U), 232Th and their daughters and 40K us-
ing the Digital Gamma-ray Spectrometry system coupled with a High Purity Germanium (HPGe; Canberra, 40% rela-
tive efficiency, 1.8 keV resolution at 1332 keV of 60Co) detector and PC based Multichannel Analyzer (MCA, upto 16k
channel). The software Genie 2000 (Canberra) and Hypermet PC have been used for data acquisition and gamma peak
analysis, respectively. Each of fifteen soils (~200g) and two standards (IAEA-Soil-6 and 800Bq liquid 226Ra sprayed in
Al2O3) were counted in cylindrical plastic pot using gamma spectrometry system for 20000 sec for the determination of
activity concentrations of the radionuclides. The samples and standards were kept in air tied condition at least for 4
weeks before gamma counting to attain the radioactive equilibrium between daughters and parents of 226Ra (238U) and
232Th decay series. The Al2O3 based 226Ra standard was used for the construction of efficiency curve covering the wide
gamma energy range. The IAEA-Soil-6 was used for quality control (QC) of the analysis. The homogeneity test and
density corrections of Al2O3 based 226Ra standard were performed and implemented for the analysis. The results of ac-
tivity concentrations have been used to assess the radium equivalent activities (Raeq) and the representative level index
(Iγr) values in the experimental soil samples. The results have been compared with other global radioactivity measure-
ments and evaluations.
Keywords: Shipbreaking Yards, HPGe Detector, Radionuclides, Activity Concentrations, Dose Rates, Radium
Equivalent Activity, Representative Level Index
1. Introduction
The world is naturally radioactive and hence human be-
ing on earth evolved in a radioactive environment. About
90% of the human radiation exposure arises from natural
sources such as terrestrial radiation, cosmic radiation,
and radon gas. Natural radionuclides of concern are tho-
rium (232Th) and uranium (238U) with their radioactive
decay chains and potassium (40K). Emanation of radon
gas (222Rn and 220Rn) into air occurs as a product of ura-
nium (238U) and thorium (232Th) decay chain respectively.
Like all other materials soil can also be the source of
radon gas [1].
Assessment of any release of radioactivity to the envi-
ronment is important for the protection of public health;
especially if the released radioactivity is a matter of di-
rect population exposure and can enter into the food
chain [2], which is a matter of indirect exposure. In the
case of the workers of the shipbreaking yards and the
peoples living round the yards, peoples are subjected to
both direct and indirect radiation exposures.
The whole activities of shipbreaking in Banglade sh are
done in an unhygienic environment with the violation of
the safety regulations. During the dismantling of the
ships different chemicals, gases, oils, ballast water, etc.,
fall in the sea water which pollute the marine environ-
Assessment of Radiological Contamination of Soils Due to Shipbreaking Using HPGe Digital Gamma-Ray Spectrometry System
Copyright © 2010 SciRes JEP
ment. Also after dismantling of the ships the scraps car-
rying the poisonous materials like chemicals, gases, oils
etc., radioactive materials, and heavy metals in its paints
and electric equipments-pollute the soil and the sur-
rounding environment where they are stored. As a result
of these, today, shipbreaking becomes a threat to the en-
vironment and hence to human health.
Now from the point of view of natural risk, it is nec-
essary to measure the environmental radiation level for
the estimation of the exposures of natural radiation
sources and to know the dose limit of public exposure.
Therefore the main object of this study is to assess the
environmental radioactive contamination in the working
environment of the shipbreaking yards of Sitakunda,
Chittagong, Bangladesh, through finding out the types
and concentrations of the radionuclides in the soil of the
yards. With the above considerations and with a view to
ensure the significant contribution of the shipbreaking to
the national economy of Bangladesh, fifteen (15) soil
samples have been collected from 5 different shipbreak-
ing yards of Sitak unda, Chittagong, with 3 samples from
each. The samples were analyzed by the HPGe detector
coupled with computer based digital gamma spectrome-
try system and sophisticated data acquisition and gamma
peak analysis software in the NAA laboratory of the In-
stitute of Nuclear Science & Technology (INST), Atomic
Energy Research Establishment (AERE), Savar, Dhaka,
2. Materials and Methods
2.1 Sample Collection and Processes
Most of the shipbreaking yards of Bangladesh are situ-
ated in different locations (Fultola, Baro Awlia, Kadam
rasul, Jahanabad, Kumira, Kattoli, etc.) under Sitakunda
thana of Chittagong District. That is why for the present
research five different shipbreaking yards of Sitakunda,
Chittagong, Bangladesh are selected as sites for sample
After cleaning the surface, soil was collected from
0-30 cm depth by auguring. Three soil samples were col-
lected in cleaned polyethylene bag from each of five
shipbreaking yards. The samples were marked separately
by giving the identification (ID) number carefully. The
name and addresses of the shipyards with soils identity
are quoted in Table 1. It is noted that in the Table 1 the
letters A, B, C are given for three different locations of
each yard.
The collected soil samples were taken in a pre-cleaned
pyrex beaker and then allowed to dry in the oven at 70C
until having constant weight. The dried soil samples were
taken then powdered by the use of an agate mortar. Fif-
teen (15) cleaned cylindrical plastic pots having the same
geometry were filled with about 200g dried powered
samples and kept in air tied condition. All the air tied
pots were remained undisturb at least for 4 weeks before
counting to attain parents-daughter equilibrium in the
238U and 232Th decay series. For example, the 222Rn from
238U decay series can easily be escaped by diffusion from
the samples during preparation. As the half-life of 222Rn
is 3.84 days, once the 222Rn escaped from the sample it is
needed at least 7 half-lives to attain equilibrium.
For measuring the natural radioactivity two standards
were used. One was IAEA Soil-6 and the other was
226Ra (liquid) sprayed into Al2O3. The Al2O3 standard
was prepared in the INST laboratory. For the prepara-
tion of Al2O3 standard 226Ra liquid having an initial ac-
tivity 800 Bq was sprayed into the Al2O3 powder. The
liquid was sprayed carefully and mixed homogeneously.
The homogeneity test of Al2O3 standard was performed
by splitting it into 6 equal folds and measured them in
the sample geometry of HPGe detector. Both the stan-
dards were also packed in the plastic pots having the
same geometry and height as that of samples. The
IAEA-Soil-6 and samples have almost the same packing
density, whereas has lower packing density. The density
corrections were performed and taken into account for
the calculation.
The accuracy of any experimental analysis depends
mainly on the performance of the detection system. On
the other, the performance of any detection system de-
pends on some parameters of the experimental set up.
Therefore in the present experiment some useful pa-
rameters of the HPGe detector were determined to ensure
the accuracy of the analysis. We have performed energy
calibration, resolution, countin g efficiencies of the HPGe
detector, Quality Control Chart (QC) for Instrumental
Quality, etc. and details of these parameters analyses
techniques are almost same as on Reference [3].
Table 1. Name and addresses of investigated shipyards with
soils identity
Name and Address of the yard Sample ID
Rising Steel Ltd.
(Ship Breaking Unit)
Fultola, Baro Aulia, Sitakunda, Chittagong.
Ziri Subader Steel
Re-Rolling Mills
(Ship Breaking Unit),
BaroAulia, Sitakunda, Chittagong.
Muhib & Sakib Steel Industries
(Ship Breaking Unit),
Kadam Rasul, Vatiary, Sitakunda, Chittagong.
M/S. Sultana Ship Breaking
Kadam Rasul, Vatiary, Sitakunda, Chittagong.
M/S. Six Star Corporation (Ship Breaking Yard),
Jahanabad, Sitakunda, Chittagong.
Assessment of Radiological Contamination of Soils Due to Shipbreaking Using HPGe Digital Gamma-Ray Spectrometry System
Copyright © 2010 SciRes JEP
2.2 Counting of the Samples and Standards
In counting system a count was taken for 20000 seconds
for each of the samples and standards of interest. The
standards for homogeneity testing were counted for 7200
second each. The spectra in all cases were saved in the
PC. A background count for the time 20000 seconds was
taken to get the background contribution in the samples
and standards.
2.3 Analysis of the Spectra
The spectra collected for the samples and standards were
analyzed in two ways: manually and by the use of analyz-
ing software Hypermet PC version –5.12. The area under
the peak of a certain gamma ray energy spectrum repre-
sents the number of counts collected only for that gamma
ray energy. For the manual evaluation of the peak area,
equal numbers of channels were taken on each side of the
peak. Hypermet PC version –5.12 gave the area automati-
cally. Both the peak analysis methods yielded almost con-
sistent peak area for the int erested radionucli de.
2.4 Interference Correction
The interference corrections have been performed in
some cases. 232Th and 226Ra have gamma peaks at 240.98
keV and at 241.98 keV energies, respectively. It is diffi-
cult for any detector to show the peaks separately, so
there is always a spectral interference between them.
Hence to calculate the correct peak area from the inter-
fered peaks, interference correction was made in the cur-
rent experiment.
The conversion of the measured to the correct peak
area [Np] is performed as:
[][][ ]
p aCorrectp abp ref
I is the gamma ray intensity, “a” denotes the
interfered peak, “b” the interfering peak, “ref” is an un-
disturbed peak from the interfering radionuclide and “
the efficiency.
2. 5 Density Corrections
In the present work density correction was made to de-
termine how the gamma rays are affected by the density
and composition of the samples & standards. For this,
IAEA-Soil-6, Al2O3 standards and gamma emitting point
sources of 60Co, 133Ba, 137Cs and 152Eu covering the low
and high energies were used. The CPS ratio of various
gamma energies emitting from point sources and passing
through both the standards were determined and plotted
as in Figure 1.
It is seen that at very low energy (80.99 keV) the
gamma-rays passing through the IAEA soil-6 standard is
10% affected compared to that through the Al2O3 stan-
dard. But at high energies there was no effect at all; the
CPS ratio is around 1.
0200 400 600 800100012001400
Gamma Energy (KeV)
CPS Ratio (IAEA-Soil-6/Al2O3)
CPS Ra tio (IAEA -So il-6/A l
Figure 1. The effect of packing density and composition of
the sample on gamma ray energies
2.6 Homogeneity Testing
The homogeneity of the Al2O3 (226Ra) standard was tested
by measuring the specific count rate (CPS/g) for six folds
for particular gamma energy. It was found that the CPS’s
were the same at 768.36 keV of 226Ra. This confirmed
the homogeneity of the Al2O3 standard (Figure 2).
3. Calculations of Activity Concentrations,
Dose Rate, Radium Equivalent Activity
and Representative Index
Soil samples were collected to determine the activity
concentrations, their corresponding dose rates and other
radioactivity indices e.g., radium equivalent activity and
representative level index, etc. The activity concentra-
tions were measured from the following relation:
1000 (2)
where A is the activity in, CPS is the net counts
per second of the experimental sample, W is the weight
of the sample in gm,
(abs) is the absolute gamma peak
detection efficiency,
I(abs) is the absolute gamma in-
tensity of the corresponding gamma ray energy.
Figure 2. Homogeneity testing of the Al2O3 standard
Assessment of Radiological Contamination of Soils Due to Shipbreaking Using HPGe Digital Gamma-Ray Spectrometry System
Copyright © 2010 SciRes JEP
To determine the activity concentrations of 226Ra
(238U), the
-ray lines 295.21, 351.92 keV (214Pb) ; 609.31
and 1120.29 keV (214Bi) were used. To determine the
activity concentrations of 232 Th, the
-ray lines 911.07,
969.11 keV (228Ac); 238.63 keV (212Pb); 583, 2614.66
keV (208Tl) were used.
The dose rate in the studied area was calculated from
the formula reported in Reference [2] as:
D=(0.0427) CRa-226 + 0.0662 CTh-232+
0.00432 CK-40) (10-8Gy.h-1) (3)
where, D-the dose rate (equivalent to the external dose
rate), CRa-226, CTh-232 and CK-40 are the average activity
concentrations of 226Ra, 232Th and 40K contents respec-
tively in the experimental soil.
The internal dose rate is assumed to be 1.2 times
higher than the external dose rate [4]
Dinternal = Dexternal 1.2 (nGy.h-1) (4)
The transformation of activity into the radium equivalent
activity, Raeq, was performed according to Reference [5] as:
 
KThRaeq CCCRa 130/107/10
 (5)
Another radiation index, named representative level index
can be de fined as per rec omm endation s of Refe rence [ 6],
KThRar CCCI 1500/1100/1150/1 
where in both cases CRa, CTh and CK are the specific ac-
tivities of 226Ra, 232Th and 40K in, respectively.
4. Results
The range and mean values of activity concentration,
dose rates, Radium Equivalent Activities (Raeq), Repre-
sentative Level Index (Iγr) and a comparative study are
shown in the Tables (2–4), respectively:
The quoted uncertainties were calculated based on the
total uncertainty budget considering 1 σ. A comparative
study was performed for the activity concentrations and
the corresponding dose rates obtained in the present work
with other previous measurements (Table 5).
The mean activity of 226Ra (238U), 232Th and 40K in fif-
teen soils samples were found to be 31.39 ± 1.77, 63.34 ±
3.27 and 364.47 ± 15.32, dry weight, respectively,
which contributes to an average gamma dose of 71.08 ±
3.64 nGy.h-1, in air, at a height of one meter above the
Table 2. The range and average values of the activity con-
Table 3. The range and average values of the dose rate
In nGy.h-1
Dose Rates Minimum Maximum Average
External (Dex) 26.06±1.81 159.79±7.00 71.08±3.64
Internal (Din) 31.27±2.17 191.75±8.40 85.30±4.37
Table 4. The range and average values of the Radium Equiva-
lent Activities (Raeq) and Representative Level Index (Iγr)
Index Minimum Maximum Average
Raeq 55.91±3.89 349.85±13.33 149.91±7.62
Iγr 0.40±0.03 2.43±0.09 1.09±0.05
Table 5. Comparisons of the activity concentrations of 226Ra,
232Th and 40K and the corresponding dose ra tes
Mean Activity
Mean Dose
Rate in
226Ra 232Th 40K D
(Ship yards) 31.3963.34 364.47 71.08 Present
Bangladesh(Dhaka)33.00016.00 574.00 81.0 [7]
India(Kotagiri) 41.00102.00 229.00 86.0 [8]
USA (California) 39.40045.60 420.00 23.0 [9]
Greece 49.00024.00 760.00 42.0 [10]
Taiwan 30.00044.00 653.00 56.6 [11]
World Average 25.00025.00 370.00 55.0 [12]
ground surface of th e yards. The activity concentration of
the anthropogenic radionuclide 137Cs was below the de-
tection limit. The results of activity concentrations have
been used to assess the radium equivalent activities (Raeq)
and the representative level index (Iγr) values in the ex-
perimental soil samples. The observed mean value of
Raeq and Iγr in soil is found to be 149.91 ± 7.62 and 1.09
± 0.05, respectively.
5. Conclusions
For the radiation protection, the accumulation of infor-
mation on natural radiation is of great importance.
Therefore the present work may be important to carry out
an approximately designed program on environmental
radioactivity monitoring-aimed at minimizing popu lation
exposure which will ensure a proper working environ-
ment in the ship breaking yards and also help to save
peoples inside and outside the yards.
Comparison of activity concentrations of different radio-
nuclides and their corresponding dose rates with world
wide references revealed that there is no anomaly ob-
served in Chittagong Shipbreaking yard in radiological
point of view. However, the created baseline data in the
present work will help to assess any radiological con-
tamination due to ship breaking activities in the study
area in future.
Activity Concentrations in
nuclides Minimum Maximum Average
226Ra 9.88±0.86 86.95±3.47 31.39±1.77
232Th 24.07±1.69 178.07±6.57 63.34±3.27
40K 68.01±4.80 792.68±29.80 364.47±15.32
137Cs ND ND ND
Assessment of Radiological Contamination of Soils Due to Shipbreaking Using HPGe Digital Gamma-Ray Spectrometry System
Copyright © 2010 SciRes JEP
6. Acknowledgement
The corresponding author A. K. M. Moinul Haque
Meaze would like to express his sincere thanks and ac-
knowledge to the Bangladesh University Grants Com-
mission (UGC) for providing fund to carry out this Project
in the fiscal year 2008–2009. The corresponding author
and Project Director also would like to thanks to the Au-
thority of the University of Chittagong, Bangladesh to
select his project for obtaining grants from the UGC. The
authors would like to thanks to the authorities of different
shipbreaking yards for their excellent cooperation.
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