This document summarizes a study that measured levels of naturally occurring radioactive materials (NORM) in petroleum products and waste materials from Egypt and Kuwait. Samples of crude oil, scale, sludge, water and sand were collected from oil wells and tested using a gamma ray spectrometer to measure concentrations of uranium-238, thorium-232 and potassium-40. The average concentrations found in Egyptian samples were 21.1 Bq/kg for radium-226, 7.6 Bq/kg for thorium-232 and 88.4 Bq/kg for potassium-40. For Kuwaiti samples, the averages were 25.2 Bq/kg, 6.1 Bq/kg and
2. concentrations in Egyptian petroleum products and
their wastes were compared with their value in
Kuwaiti petroleum products and their wastes and
with the worldwide recommended limits as well.
Moreover, the radiological hazard indices of radium
equivalent activity (Raeq), external (Hex) and internal
hazard indices (Hin), alpha and gamma indices and
annual effective dose were calculated and compared
with the worldwide safety values recommended by
the United Nations Scientific Committee on the
Effects of Atomic Radiation (UNSCEAR) and
International Atomic Energy Agency (IAEA).
MATERIALS AND METHODS
Sample Preparation
The released amount of ionizing radiation from oil
products and their wastes is a very important issue
for radiation protection point of view since it varied
from the oil well to others, depending on the rocks
of the reservoir that have various quantities of nat-
ural radionuclides of 226
Ra (238
U), 232
Th and 40
K.
Several researchers highlight the varied level of
NORM (226
Ra (238
U), 232
Th and 40
K) in oil pro-
ducts and their wastes maintained high-level natural
radionuclides. For example, Abo-Elmagd et al.(9)
,
reported that oil products and their waste from the
South Sinai governorate, Egypt maintained a high
level of NORM, Mansour et al.(13)
, reported that oil
products and their wastes of the Eastern Desert of
Egypt maintained also a high level of natural radio-
nuclides. Also, Hassan et al.(16)
, reported that a high
level of emanated radon from oil products and their
wastes of the Eastern Desert of Egypt. Therefore, it
is very important to evaluate the level NORM in oil
products and wastes in all oil wells.
In the present work, eight samples of different types
of oil, one sample of water, three samples of sludge,
one sample of scale and four samples of sand were
collected from the oil wells of Greater Burgan, South
Fuwars and Ratqa located in Kuwait, as shown in
Table 1 and Figure 1. On the other hand, four samples
of different types of oil, one sample of water, five sam-
ples of sludge, one sample of liquid gas and one sam-
ple of sand were collected from the three main oil
provinces in Egypt (Western Desert, Nile Delta and
Gulf of Suez (Ras Gharib)), as shown in Table 2 and
Figure 2. The regions that the samples were collected
from the regions where oil production is actively con-
ducted by the government of Egypt and Kuwait. The
wells mentioned in the current study are used as a
baseline to investigate the radiation levels of all
regions. The work is a continuous work for the previ-
ously published papers for other regions(9, 13, 16)
.
The solid samples were crushed into a fine powder
and then were sieved through a 1-mm mesh size to
remove the larger grain size to be more homogenous.
These solid samples, then were dried in an oven at
110°C for 24 h to ensure complete dryness from
moisture. After moisture removal, the samples were
cooled down to room temperature in a desiccator.
The prepared samples were packed into airtight plas-
tic containers, (6-cm diameter and 8-cm height)
made from polyethylene. The liquid samples were
packed into the same geometry plastic containers.
Table 1. Specific activity concentrations of 226
Ra, 232
Th and 40
K in the Kuwaiti petroleum products and wastes materials.
Sample type Location Code Activity concentrations (Bq kg−1
)
226
Ra 232
Th 40
K
Heavy eocene oil Greater Burgan (KO1) ND ND 13.6 ± 1.1
Heavy crude oil Greater Burgan (KO2) 6.8 ± 3.2 4.8 ± 1.3 81.2 ± 10.2
Heavy crude oil South Fuwars (KO3) 17.0 ± 6.4 ND 126 ± 12
Crude oil South Fuwars (kO4) ND ND 56.6 ± 16.7
Crude oil Greater Burgan (KO5) 7.1 ± 4.3 10.5 ± 5.1 89.9 ± 10.2
Crude oil Ratqa (KO6) 16.3 ± 0.5 2.2 ± 0.6 84.9 ± 1.8
Oil Ratqa (KO7) 5.8 ± 1.3 4.1 ± 2.2 49.8 ± 5.5
Plankton oil Greater Burgan (KP1) 126 ± 3 ND 81.6 ± 6.9
Plankton oil Greater Burgan (KP2) 2.8 ± 0.1 ND 59.6 ± 1.0
Water Ratqa (KWO1) 3.9 ± 2.6 ND 54.2 ± 4.6
Sludge Greater Burgan (KSL1) 94.2 ± 5.3 27.7 ± 0.6 ND
Sludge Ratqa (KSL2) 42.4 ± 11.8 6.0 ± 2.5 81.8 ± 6.8
Sludge Ratqa (KSL3) 13.1 ± 1.7 1.5 ± 1.2 54.8 ± 5.8
Sand South Fuwars (KS1) 55.3 ± 8.9 3.9 ± 3.5 183 ± 14
Sand Greater Burgan (KS2) 3.8 ± 2.1 3.2 ± 2.5 43.4 ± 4.6
Sand Ratqa (KS3) 3.0 ± 1.8 ND 49.5 ± 4.4
Sand Ratqa (KS4) 28.8 ± 2.4 5.4 ± 0.5 69.9 ± 6.2
Average 25.2 ± 3.4 6.1 ± 2.2 67.8 ± 6.4
ND is a non-detectable value.
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3. All containers were carefully sealed with adhesive to
prevent any possibility of escaping of radon (222
Rn)
or thoron (220
Rn)(6, 17)
and stored for 1 month in
order to achieve radioactive secular equilibrium
between 226
Ra and 222
Rn. Simultaneously, an empty
same geometry container was sealed and left in the
same period to be applied for future background
measurement.
Measurement of Radionuclide Concentrations
The natural radionuclide concentrations of 226
Ra,
232
Th and 40
K in the samples of this study were mea-
sured using an High Purity Germanium detector of
vertical closed-end coaxial manufactured by
Canberra. This detector has an accurately measured
efficiency and an energy resolution of 2.1 keV at
Figure 1. The location map of oil fields in Kuwait.
Table 2. Specific activity concentrations of 226
Ra, 232
Th and 40
K in the Egyptian Petroleum products and wastes materials
ND is a non-detectable value.
Sample type Location Code Activity concentrations (Bq kg−1
)
226
Ra 232
Th 40
K
Crude oil The Nile Delta (EO1) 14.9 ± 1.2 3.4 ± 1.4 77.3 ± 3.0
Crude oil The Nile Delta (EO2) 10.2 ± 1.9 ND 66.5 ± 10.0
Crude oil Suez (EO3) 13.4 ± 4.4 6.2 ± 2.8 91.8 ± 7.1
Crude oil Suez (EO4) 21.3 ± 5.4 ND 121 ± 15
Liquid gas The Nile Delta (ELG1) 10.8 ± 6.5 ND 143 ± 16
Water Suez (EWO1) 3.7 ± 1.7 ND 50.2 ± 4.5
Sludge The Nile Delta (ESL1) 7.6 ± 2.4 8.4 ± 2.6 52.2 ± 8.7
Sludge The Nile Delta (ESL2) 12.9 ± 1.4 3.1 ± 1.6 54.5 ± 5.4
Sludge The Nile Delta (ESL3) 20.6 ± 2.1 4.4 ± 1.9 51.9 ± 4.9
Sludge Suez (ESL4) 11.3 ± 5.1 14.8 ± 2.8 73.4 ± 14.1
Sludge Suez (ESL5) 123 ± 5 48.3 ± 0.8 241 ± 3
Sand The Nile Delta (ES1) 3.4 ± 1.2 3.1 ± 1.8 37.8 ± 6.7
Average 21.1 ± 3.2 7.6 ± 1.3 88.4 ± 8.2
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4. 1.33 MeV of gamma ray line of 60
Co (located at the
Egyptian Atomic Energy Agency, Cairo, Egypt). In
order to reduce the effects of background measured
by the detector, it is shielded with a cylindrical lead
(Pb) of thickness 10 cm which contains an inner con-
centric cylinder of Cu with a thickness of 8 mm. The
detector is connected to a data acquisition system,
using a personal computer, which has a Multi-
Channel-Analyzer (8192 channels). The data ana-
lysis was carried out via gamma spectroscopy pro-
gram of Genie 2000 spectral analysis software. The
HPGe detector’s peak calibration and efficiency were
carried out using standard point source package (RSS-
8) of eight radionuclides of Cs-137, Ba-133, Cd-109,
Zn-65, Co-60, Co-57, Mn-54 and Na-22 supplied by
the IAEA. For bulk measurements, the 40
K in KCl
standard bulk solution was used as a normalizing fac-
tor. The bulk source was packaged in the same con-
tainer geometric as those used for samples.
The natural radionuclide concentrations of 238
U
(226
Ra), 232
Th and 40
K in each sample were detected
over a time frame of around 24 h. Since 226
Ra and
its progenies produce ~98.5% of radiological effects
of natural uranium series, the contribution of natural
238
U and the precursors of 226
Ra were ignored.
Thus, 226
Ra was considered to be the reference of the
238
U series instead of 238
U(17, 18)
. 226
Ra specific
activity was measured from the gamma rays lines at
the energies of 351.9 keV (36.6%) and 295.2 keV
(18.5%) associated with the decay 214
Pb, and at the
energies of 609.3 keV (46.1%) and 1120 keV (15%)
associated with the decay 214
Bi, as shown in
Figure 3. On the other hand, thorium (232
Th) spe-
cific activity was estimated from the gamma rays of
energies of 911.1 keV (29%) associated with the
decay of 228
Ac, 583.1 keV (84.5%) associated with
the decay of 208
Tl and 238.6 keV (43.6%) associated
with the decay of 212
Pb as shown in Figure 3.
Finally, potassium (40
K) specific activity was esti-
mated from the gamma ray of the energy of
1460.9 keV (10.67%) associated with the decay 40
K
itself(19, 20)
. The self-attenuation and coincidence
summing effects were ignored in this study. The
activity concentrations of natural radionuclides, A,
(Bq kg−1
) are calculated from Eq (1)(19, 21)
.
ρ ε
= ( )
A
C
wt
1
i i
where C is the net count above the background, pi is the
absolute emission probability of each gamma ray (men-
tioned in brackets after gamma rays energies), w is the
net dry sample weight (kg), The samples’ weights were
ranged between 350 and 500 g, t is the measurement
time and εi is the absolute efficiency of the detector is
associated with each gamma rays energy value.
Figure 2. The location map of oil fields in Egypt.
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5. RESULTS AND DISCUSSION
The goal of this work is to measure the activity con-
centrations of 226
Ra, 232
Th and 40
K in some ran-
domly selected materials of different types of oil,
scale, sludge, water and sand from oil wells located in
both Egypt and Kuwait. The results of this study
are summarized in Tables 1 and 2. The activity con-
centrations of 226
Ra, 232
Th and 40
K in petroleum
products and their wastes were varied from ND (non-
detectable value, KO4) to 123 ± 3 (KP1) Bq kg−1
with a
mean value of 25.2 ± 3.4 Bq kg−1
for 226
Ra, ND (KO1)
to 27.7 ± 0.6 (KSL1) Bq kg−1
with a mean value
of 6.1 ± 2.2 Bq kg−1
for 232
Th and ND (KSL1)
to 183.39 ± 13.73 (KS1) Bq kg−1
with a mean value
of 67.8 ± 6.4 Bq kg−1
for 40
K, in the selected samples
from Kuwait, as shown in Figures 4–6 and Tables 1.
On the other hand, the Egyptian samples were varied
from 3.4 ± 1.2 (ES1) to 123 ± 5 (ESL5) Bq kg−1
with a
mean value of 21.1 ± 3.2 Bq kg−1
for 226
Ra, ND
(EO2) to 48.3 ± 0.8 (ESL5) Bq kg−1
with a mean value
of 7.6 ± 1.3 Bq kg−1
for 232
Th and 37.8 ± 6.7
(ES1) to 241 ± 3 (ESL5) Bq kg−1
with a mean value
of 88.4 ± 8.2 Bq kg−1
for 40
K, respectively, as shown
in Figures 4–6 and Tables 2. The maximum activity
levels for all measured radionuclides in selected samples
were 126 ± 3 Bq kg−1
(KP1) of 226
Ra, 27.7 ± 0.6 (KSL1)
Bq kg−1
of 232
Th and 183 ± 14 (ESL5) Bq kg−1
of 40
K for Kuwaiti samples while for Egyptian sam-
ples, they were 123 ± 5 Bq kg−1
(ESL5) of 226
Ra,
48.3 ± 0.8 (ESL5) Bq kg−1
of 232
Th and 241 ± 3
(ESL5) Bq kg−1
of 40
K, respectively. The radionuclide
concentration of Egyptian and Kuwaiti petroleum
products and their wastes were comparable with
almost the same average values. However, specific
activities of 226
Ra, 232
Th and 40
K in sludge samples
were higher than their values in crude oil, water and
sand for Egyptian samples. Similarly, the Kuwaiti
radionuclide concentration of 226
Ra in the plankton
oil refinery of greater Burgan oil well was higher
than its value in all other samples, 232
Th in sludge of
greater Burgan oil well was higher than its value in
all other samples and 40
K in sand of south Fuwars
was higher than its value in all other samples. The
obtained results indicate that the specific activity
concentrations in all selected material from Egypt
and Kuwait were comparable or less than the
global median specific activity concentrations in
soil of 35, 30 and 400 Bq kg−1
for 226
Ra, 232
Th and
40
K, respectively, reported by UNSCEAR(21, 22)
.
Moreover, the radionuclide concentrations in the
studied materials were much lower than the exemp-
tion level for NORM of 1 Bq g−1
for uranium and
thorium and 10 Bq g−1
for 40
K recommended by the
IAEA basic safety standards(23, 24)
. Thus, there is no
radiological risk for worker or public dealing with
those materials so that the radiation exposure from
the selected material can be ignored. The values of
natural radionuclides in the present study were
compared with their values in the same material
previously described in the literature, as pictured in
Table 3.
In order to compute the radiation hazards asso-
ciated with materials maintained various levels of
226
Ra, 232
Th and 40
K in a single quantity, the radium
equivalent activity (Raeq) has been introduced by
UNSCEAR(21, 22, 34)
, Eq. 2.
= + + ( )
Ra A A A
1.43 0.077 2
eq Ra Th K
where, ARa, ATh and AK are activity concentrations
of 226
Ra, 232
Th and 40
K, respectively, in Bq kg−1
.
The radium equivalent index was calculated based
Figure 3. Typical gamma ray spectrum of natural radionuclides of Egyptian (ESL5) and Kuwait (KSL1) sludge waste
materials.
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6. on the assumption that 370 Bq kg−1
of 226
Ra,
259 Bq kg−1
of 232
Th and 4810 Bq kg−1
of 40
K produce
the same equivalent dose of gamma ray. For the
sake of safety, Raeq activity concentration of material
should be <370 Bq kg−1
to keep gamma ray dose below
1.5 mSv y−1(35–37)
. Radium equivalent concentration
in Egyptian petroleum products and wastes was ranged
from 7.5 ± 2.0 Bq kg−1
(EWO1) to 210 ± 7 Bq kg−1
(ESL5) with a mean value 38.8 ± 5.8 Bq kg−1
while for
Kuwaiti samples, it was ranged from 1.7 ± 1.0 Bq kg−1
(KO1) to 134 ± 6 Bq kg−1
(KSL1) with a mean value
of 34.4 ± 5.6 Bq kg−1
, as shown in Figure 7, and
Tables 4 and 5. The Radium equivalent of all investi-
gated petroleum products and wastes was less than the
recommended limit of 370 Bq kg−1
which implies that
these materials have no radiological hazards and can be
safely used in various industries.
Radiation hazard mainly comes from external
gamma rays emitted from natural radionuclides
of 226
Ra, 232
Th and 40
K. The external hazard of gamma
0
20
40
60
80
100
120
EO1 EO2 EO3 EO4 __ __ __ __ __ ELG1 EWO1 ESL1 ESL2 ESL3 ESL4 ESL5 ES1 __ __ __
KO1 KO2 KO3 KO4 KO5 KO6 KO7 KP1 KP2 __ KWO1 KSL1 KSL2 KSL3 __ __ KS1 KS2 KS3 KS4
Activity
Conc.
Bq/Kg
Sample Code
Ra-226 Activity
Egypt Kuwait
Figure 4. Specific activity concentrations of Ra-226 in Egyptian and Kuwaiti samples.
0
5
10
15
20
25
30
EO1 EO2 EO3 EO4 __ __ __
__ __ EWO1
EWG1 ESL2
ESL1 ESL3 ESL4 ESL5 ES1 __
__ __
KO1 KO2 KO3 KO4 KO5 KO6 KO7 KP1 KP2 __ KWO1 KSL1 KSL2 KSL3 __ __ KS1 KS2 KS3 KS4
Activity
Conc.
Bq/Kg
Sample Code
Th-232 Activity
Egypt Kuwait
Figure 5. Specific activity concentrations of Th-232 in Egyptian and Kuwaiti samples.
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7. rays can be expressed by the external hazard index
(Hex) which was determined from Eq. (3)(34)
;
= + + ( )
H
A A A
370 259 4810
3
ex
Ra Th K
where, ARa, ATh and AK are the activities of 226
Ra,
232
Th and 40
K, respectively, in Bq kg−1
. Normally,
the external hazard index of a material should be
less than unity in order to limit the external gamma
radiation dose to be <1.5 mSv y−1
. In this study, the
average calculated values of external hazard index
for Egyptian and Kuwaiti petroleum products and
wastes were of 0.11 ± 0.02 and 0.09 ± 0.02 (Tables 4
and 5). The external hazard index of all studied sam-
ples was less than the recommended limit which
implies the external radiation hazard could be
ignored.
In addition to the external hazard, another factor
should be taken into account because of radon, and
its progenies as they are hazardous to the respiratory
organs is called an internal hazard index. It is caused
by radionuclides of 226
Ra, 232
Th and 40
K in add-
itional to radon and its progenies of 218
Po, 214
Pb,
210
Pb and 210
Bi. The internal hazard index (Hin) can
be defined as(34)
;
= + + ( )
H
A A A
185 259 4810
4
in
Ra Th K
For the safe use of a material, Hin should be less
than unity in order to ignore the hazards of radon
and its products on the respiratory organs. The
average value of the internal hazard index was 0.16
± 0.03 (Table 5) for all of the Egyptian and Kuwaiti
samples, which are lower than the recommended
limit. Thus, the use of Egyptian and Kuwaiti materi-
als has insignificant radiation hazards.
Normally, the petroleum products and wastes,
maintained natural radionuclides; hence they could
be a possible source of radiation exposure for the
public and workers. Thus, regular assessment of their
radiation exposure would be beneficial for the public
and workers health and safety. Radiation exposure is
mainly due to gamma radiation emitted from those
materials. The absorbed dose rate (D) due to gamma
rays in the air at 1 m of air above the selected materi-
als which maintains a uniform distribution of nat-
ural radionuclides of 226
Ra, 232
Th and 40
K, can be
calculated from the following equation(21)
.
( ) = + +
( )
−
D nGy h A A A
0.462 0.621 0.042
5
Ra Th K
1
The absorbed dose rate was calculated for the
samples as shown in Tables 6 and 7. The radiation
absorbed dose rate was varied from 3.8 ± 1.0 nGy
h−1
(EWO1) to 96.4 ± 3.2 nGy h−1
(ESL5) with a
mean value of 18.1 ± 2.7 nGy h−1
for Egyptian pet-
roleum products and wastes. For Kuwaiti samples,
the absorbed dose varied from 0.87 ± 0.48 nGy h−1
(KO1) to 61.2 ± 1.6 nGy h−1
(KP1) with a mean
value of 16.1 ± 2.6 nGy h−1
. All the selected
Egyptian and Kuwaiti materials had an absorbed
radiation dose value lower than the recommended
value by UNSCEAR(21)
, of 59 nGy h−1
except two
0
50
100
150
200
250
EO1 EO2 EO3 __
__ __ __
__ __ EWO1
ELG1 ESL2 ESL3
ESL1 ESL4 ESL5 ES1 __
__ __
KO1 KO2 KO3 KO4 KO5 KO6 KO7 KP1 KP2 __ KWO1 KSL1 KSL2 KSL3 __ __ KS1 KS2 KS3 KS4
Activity
Conc.
Bq/Kg
Sample Code
K-40 Activity
Egypt Kuwait
Figure 6. Specific activity concentrations of K-40 in Egyptian and Kuwaiti samples.
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8. samples of KP1 (61.2 ± 1.6) nGy and KSL1 (60.5 ±
2.8) nGy from Kuwaiti samples and one sample of
ESL5 (96.4 ± 3.2) nGy from Egyptian samples, as
given in Tables 6 and 7. Thus, except for three sam-
ples of KP1, KSL1 and ESL5, all the Egyptian and
Kuwaiti samples have no pose of radiation exposure.
Furthermore, the annual effective dose (E) from
gamma rays emitted from 226
Ra, 232
Th and 40
k in
the samples was calculated from Eq. (6)(22, 34)
.
= ( × ( ) × × ( )
( )
− −
E D nGy h h y O C Sv Gy
8760 /
6
1 1
where, O is the occupancy factor and C is the
absorbed to the effective dose conversion factor of
0.7 Sv/Gy(38)
. The annual effective dose due to gam-
ma rays emitted from the radionuclides of 226
Ra,
232
Th and 40
K in the selected materials was calcu-
lated within two scenarios. The first scenario (effect-
ive and actual scenario) is that workers in fields (well
locations) and factories are exposed to petroleum
products/wastes maintained radionuclides of 226
Ra,
232
Th and 40
K, for 1753 hy−1
(outdoor occupancy
factor equals ~0.2, 1753 hy−1
= 0.2 × 8760 hy−1
),
while the other scenario is that a certain population
in houses is exposed for 7012 hy−1
(outdoor occu-
pancy factor equals ~0.8, 7012 hy−1
= 0.2 × 8760 h
y−1
). This scenario is not effective in the present
study, but it was used to show the possible highest
radiological risk.
In the first scenario (effective and actual scenario),
the annual effective dose from gamma rays emitted
by 226
Ra, 232
Th and 40
k in the samples varied from
4.6 ± 1.2 μSv y−1
(EWO1) to 118 ± 4 μSv y−1
(ESL5)
with a mean value of 22.2 ± 3.3 μSv y−1
for the
Egyptian samples. On the other side, the Kuwaiti
samples varied from 1.1 ± 0.6 μSv y−1
(KO1) to 75.0
± 2.0 μSv y−1
(KP1) with a mean value of 19.8 ± 3.1
μSv y−1
, as summarized in Tables 6 and 7 and
Figure 8. Whereas in the second scenario, the annual
effective dose ranged from 18.4 ± 4.8 μSv y−1
(EWO1) to 472.8 ± 15.6 μSv y−1
(ESL5) for the
Egyptian samples and from 4.4 ± 2.4 μSv y−1
(KO1)
to 300 ± 7.6 μSv y−1
(KP1) for the Kuwaiti samples,
as seen in Tables 6 and 7. The calculated annual
Table 3. Comparison of activity concentrations of 226
Ra, 232
Th and 40
K in petroleum products and wastes materials of
various countries.
Sample type Country Activity concentrations (Bq kg−1
) Reference
226
Ra 232
Th 40
K
Scale Brazil 18–22 19.2–21.9 417–432 (25)
Scale Saudi Arabia 1284–3613 12–27 — (12)
Scale Middle East 12–245.8 1.7–40.1 484.8–9850 (3)
Scale Egypt 9140–285 823 427–34 339 51–1031 (14)
Scale Syria 0.3–1520 0.6–868 — (1)
Scale Tunisia 59 ± 7 82 ± 12 64 ± 10 (26)
Sludge Nigeria 54.5–94.2 33.3–71.2 462.1–712.4 (2)
Sludge Egypt 5.5–1785.8 < LD–885 < LD–125.5 (11)
Sludge Brazil < LLD–413 400 < LLD–117 900 417 000–432 000 (15)
Sludge UK 1.70–8.20 0.03–0.51 — (20)
Sludge Malaysia 123–153 37–42 — (27)
Sludge Iraq 1.5 0.2 2.5 (28)
Sludge Turkey < 1–809.2 < 0.8–302.5 < 3.8–623 (29)
Sludge Egypt 18.032 13.257 1261 (30)
Sludge Albania 18–20 21–22 175–348 (31)
Oil Kuwait 1.8–2.5 1.6–1.8 16.1–27.1 (32)
Heavy oil Syria 77–135 24–42 — (1)
Crude oil Ghana < 0.12–10.14 < 0.11–12.45 < 0.15–34.39 (4)
Crude oil Saudi Arabia < LD 0.05–0.3 0.2–1.8 (5)
Crude oil Turkey < 1– < 5.6 < 1–4.8 < 1– < 11 (29)
Water Egypt 26.5–217 < LD–93 < LD–248.7 (11)
Water Iran 0.1–30 — — (33)
Oil Kuwait ND–17.0 ND–10.5 13.6–126 Present study
Oil Egypt 10.2–21.3 3.4–6.2 66.5–121 Present study
Sludge Kuwait Sludge 1.5–28 ND–54.8 Present study
Sludge Egypt Sludge 3.1–48.3 52–241 Present study
Sand Kuwait 3.8–55.3 3.2–5.4 43–183 Present study
Sand Egypt 3.4 ± 1.2 3.1 ± 1.9 37.8 ± 6.7 Present study
8
N. M. HASSAN ET AL.
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9. effective dose with both scenarios was less than the
worldwide average annual effective dose of 480 μSv
y−1(22)
. As well, it is much lower than 1 mSv for
the public or 20 mSv for workers recommended by
the International Commission on Radiological
Protection (ICRP-103)(35)
.
The gamma ray radiation hazards associated with
the natural radionuclides in materials can be evalu-
ated by means of the radioactivity level index called
gamma index (Iγ). According to the European
Commission guidelines, Iγ should be <1 for a
gamma radiation dose of 1 mSv y−1(23)
. The gamma
ray index (Iγ) can be calculated from Eq. (7).(39)
= + + ( )
γ
I
C C C
300 200 3000
7
Ra Th K
The Iγ of the Egyptian samples varied from 0.03
± 0.01 for (EWO1) to 0.73 ± 0.02 for (ESL5) with
a mean value of 0.14 ± 0.02. For the Kuwaiti sam-
ples, it varied from 0.007 ± 0.004 for (KO1) to
0
20
40
60
80
100
EO1 EO2 EO3 EO4 __ __ __
__ __ EWO1
ELG1 ESL2 ESL3
ESL1 ESL4 ESL5 ES1 __ __
__
KO1 KO2 KO3 KO4 KO5 KO6 KO7 KP1 KP2 __ KWO1 KSL1 KSL2 KSL3 __ __ KS1 KS2 KS3 KS4
Activity
Conc.
Bq/Kg
Sample Code
Specific activities concentrations of Radium Equivalent (Raeq)
Egypt Kuwait
Figure 7. Radium equivalent activity concentrations of Egyptian and Kuwaiti samples.
Table 4. Radium equivalent, external and internal hazard indices of Kuwaiti samples.
Sample code Radium equivalent (Raeq) (Bq Kg−1
) External index (Hex) Internal index (Hin)
(KO1) 1.7 ± 1.0 0.005 ± 0.003 0.006 ± 0.005
(KO2) 14.8 ± 10.9 0.040 ± 0.029 0.058 ± 0.038
(KO3) 26.7 ± 7.3 0.072 ± 0.020 0.118 ± 0.037
(kO4) 4.4 ± 1.3 0.012 ± 0.003 0.012 ± 0.003
(KO5) 29.0 ± 12.4 0.078 ± 0.034 0.098 ± 0.045
(KO6) 26.0 ± 1.4 0.070 ± 0.004 0.114 ± 0.005
(KO7) 15.5 ± 4.8 0.042 ± 0.013 0.058 ± 0.017
(KP1) 132 ± 3 0.356 ± 0.009 0.695 ± 0.017
(KP2) 8.7 ± 0.9 0.024 ± 0.002 0.031 ± 0.003
(KWO1) 8.1 ± 3.0 0.022 ± 0.008 0.032 ± 0.015
(KSL1) 134 ± 6 0.362 ± 0.017 0.616 ± 0.031
(KSL2) 57.2 ± 15.9 0.155 ± 0.043 0.269 ± 0.075
(KSL3) 19.5 ± 3.8 0.053 ± 0.010 0.088 ± 0.015
(KS1) 75.0 ± 14.9 0.203 ± 0.040 0.352 ± 0.064
(KS2) 11.8 ± 6.0 0.032 ± 0.016 0.042 ± 0.022
(KS3) 6.8 ± 2.1 0.018 ± 0.006 0.026 ± 0.010
(KS4) 41.8 ± 3.6 0.113 ± 0.010 0.191 ± 0.016
9
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11. 0.453 ± 0.021 for (KSL1) with a mean value of
0.121 ± 0.019, as can be seen in Tables 6 and 7. All
the measured samples had a radioactivity level
index <1 so that these samples can be used without
special precautions(39)
.
Alpha radiation due to the released radon from
samples is called alpha index (Iα) which can be com-
puted from Eq. (8),(39)
. The alpha index should be
less than unity to reflect a radium concentration
value <200 Bq kg−1
(the upper recommended value)
which leads to a maximum released radon concen-
tration <200 Bq m-3
.
= ( )
∝
I
A
200
8
Ra
Alpha index of the Egyptian samples varied from
0.017 ± 0.006 (ES1) to 0.613 ± 0.027 (ESL5) with a
mean value of 0.105 ± 0.016. For Kuwaiti samples,
it varied from the ND value (KO4) to 0.628 ± 0.014
(KP1) with a mean value of 0.119 ± 0.016, as seen in
Tables 6 and 7. Accordingly, the values of Alpha
index for Egyptian and Kuwaiti petroleum products
and wastes were much lower than unity which
implies that all the study materials do not have radi-
ation hazard for a worker and the general public.
CONCLUSION
Natural radioactivity concentrations of 226
Ra, 232
Th
and 40
K, in petroleum products and wastes of crude
oil, water, sludge and contaminated sand collected
various petroleum well fields located Egypt and
Kuwait, were ranged from 3.35 ± 1.22 to 122.55 ±
5.42 Bq kg−1
for 226
Ra, ND value to 48.28 ±
0.82 Bq kg−1
for 232
Th and 37.83 ± 6.70 to 240.59 ±
3.42 Bq kg−1
for 40
K Egyptian samples and from
ND to 125.52 ± 2.82 Bq kg−1
for 226
Ra, ND to 27.65 ±
0.63 Bq kg−1
for 232
Th and ND to 183.39 ±
13.73 Bq kg−1
for 40
K, for Kuwaiti samples. The
radionuclides concentrations of Egyptian and Kuwaiti
petroleum products and wastes were less than the
recommended limits of UNSCEAR and ICRP for
earth’s crust and the recommended values of IAEA as
well. Moreover, the radiological hazard indexes, of
radium equivalent activities (Raeq), external and
internal indexes, gamma and alpha indexes and
annual effective doses of the Egyptian and Kuwaiti
petroleum products and wastes were less than
the recommended values of 370 Bq kg−1
, 1, 1 and
480 μSv y−1
. The absorbed dose of all the studied
samples was less than the recommended value of
59 nGy h−1
except only three samples of KP1,
KEL1 and ESL5. Thus, we deduce that the selected
petroleum products and wastes (except KP1, KSL1
and ESL5) have not caused significant radiological
risk on the worker or the public but might need
monitoring for long-term effective evaluation.
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