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J o u r n a l o f R a d i a t i o n R e s e a r c h and A p p l i e d S c i e n c e s 8 ( 2 0 1 5 ) 5 6 2e5 6 9
HOSTED BY Available online at ww
ScienceDirectJournal of Radiation Research and Applied
Sciencesjournal homepage: ht tp: / /www.elsevier .com/locate/ j r ras
Depth determination of the subsurface uraniumdeposits using CR-39 cylindrical technique inGneissoic granitic rocks, Abu Rushied area,Southeastern Desert, Egypt
Sayed F. Hassan*
Nuclear Materials Authority, P.O. Box:530, El Maadi, Cairo, Egypt
a r t i c l e i n f o
Article history:
Received 26 April 2015
Received in revised form
17 June 2015
Accepted 24 June 2015
Available online 7 July 2015
Keywords:
Cylindrical technique
Gneissoic granitic rocks concentra-
tion gradient
* Corresponding author. Tel.: þ201156754301E-mail address: said_fahmy_nma@yahoo
Peer review under responsibility of The Ehttp://dx.doi.org/10.1016/j.jrras.2015.06.0091687-8507/Copyright© 2015, The Egyptian Socopen access article under the CC BY-NC-ND li
a b s t r a c t
Using solid state nuclear track detectors and employing CR-39 cylindrical technique, the
depth of the subsurface uranium deposits were determined. This techniques depends
mainly on the nuclear track detector situated in zigzag form inside a polyethylene cylinder
of 65 cm length and 7 cm diameter. This technique was applied on a borehole in a granite
mass Abu Rushied area, southeast area desert. The obtained results revealed that, the
depth of U -ore deposited reached about 89 m with thickness nearly 24 m. The obtained
data for radon concentrations were also used for the determination of the exhalation rates,
the measured values for exhalation rate (mBqm�2h�1) varies between 6.14E-03 at h ¼ 50 cm
and 4.53E-02 at h ¼ 10 cm, The obtained values are comparable with that recorded for the
granite type of rock.
Copyright © 2015, The Egyptian Society of Radiation Sciences and Applications. Production
and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/).
1. Introduction
Radon atoms are continuously generated in the rock matrix
and emanate into the air-filled pore space, from where some
of them reach the ground surface and escape into the atmo-
sphere (Anjos et al., 2010a; Estellita et al., 2010; Steinitz,
Piatibratova, & Kotlarsky, 2011). The generation of radon de-
pends on the uranium concentration and the nature of the
parent mineral. However, the transmission to atmosphere is
largely independent of these.Most of the uranium in rocks can
be attributed to discrete uranium bearingminerals evenwhen
there is only a few parts per million of uranium present (Anjos
et al., 2006; Veiga et al., 2006).
..com.
gyptian Society of Radiat
iety of Radiation Sciencescense (http://creativecom
Clearly, as radon is a gas with a short half-life, its chance to
escape from the mineral matrix to the environment is higher
when it is generated near the superficial margin of that min-
eral. The openness and imperfections in the lattice are
important controls, as is the specific surface area of the min-
eral. Once the radon is released from the parentmineral to the
intergranular region several factors take over, such as the fluid
transmission features of the rock, the nature of fractures and
disaggregation features. Measurement of temporal variation
of radon in soil or water has given evidence that the emana-
tion of radon can be related to tectonic disturbances in the
Earth's crust (Planinilc et al., 2001; Chyi et al., 2002). These
special characteristics make the Rn-222 isotope useful in
ion Sciences and Applications.
and Applications. Production and hosting by Elsevier B.V. This is anmons.org/licenses/by-nc-nd/4.0/).
J o u rn a l o f R a d i a t i o n R e s e a r c h and A p p l i e d S c i e n c e s 8 ( 2 0 1 5 ) 5 6 2e5 6 9 563
earthquake prediction, geological and tectonic studies; the
location of uranium and oil deposits (Singh, Sharma, Sunil, &
Randhawa, 2006; Bossew, 2003).
Radon detection and measurement has several useful ap-
plications, for example, as a pointer to buried uranium de-
posits, as a tracer of moving air and groundwater masses, as
an indicator of geological faults and, more recently, as a
possible tool for earthquake prediction. There are many re-
ports which suggest that measurements of radon concentra-
tions in groundwater or soil gas, or both, may provide a useful
early warning of imminent seismic activity. Radon in the
ground is studied for the locations of uranium ores,
geothermal resources, and hydrocarbon deposits and for the
prediction of earth-quakes or volcanic eruptions. The impor-
tance of radon in uranium exploration is due to its radioac-
tivity, its relation to uranium and its inertness. The
connection with uranium makes it useful as a pathfinder
element when searching for uranium ores. Owing to its
inertness, radon can travel long distance within the earth'scrust, which makes it an effective tracer for understanding
geophysical processes. Themobility of radon can be helpful in
providing useful information concerning the possible exis-
tence of subsurface uranium mineralization. Therefore, if
there exists someuraniummineralization at a certain depth, a
fraction of radon is produced and reaching the earth's surface
before being lost in the process of natural decay. Thus, if some
convenient and accurate method is employed for measure-
ment of radon gas, an area showing high anomalous radon
signals could be delineated and presence of uranium miner-
alization is outlined (King, 1980; Gingrich, 1984) This work
aims to estimate the depth of the uranium deposits before
drilling using CR-39 cylindrical technique employing Solid
State Nuclear Track Detector, and determination of the
exhalation rates in the selected site.
2. General geology of the tested area
Abu Rushied area is located about 45 km west the mouth of
Wadi El Gemal which lies south of Marsa Alam City on the Red
Sea coast. It is rugged topographywithmoderate to high relief,
the area is characterized by several rock varieties that
dissected by strike slip faults represented by ENE-WSW, NeS,
EeW, NEeSW and NWeSE with sinistral and dextral move-
ments. Fig. 1 shows the detailed geologic map of Abu Rushied
area, Southeastern Desert, Egypt.
The main rock units of Abu Rusheid area are: 1) layered
metagabbros 2) ophiolitic m�elange 3) cataclastic rocks; 4)
granitic rocks (porphyritic biotite monzogranites, biotite
monzogranites and two mica monzogranites) and 5) post-
granite dykes and veins.
2.1. Field spectrometry
Gamma-ray survey of the Abu Rushied area has been carried
out in the field using RS-230 BGO Super-Spec portable radia-
tion detector, handheld unit spectrometer survey meter with
high accuracy (Probable measurement errors about 5%). This
detector is full assay capability with data in K%, eU (ppm), Ra
(ppm) and eTh (ppm), no radioactive sources required for
proper operation. The detector is independent private com-
pany (Radiation Solutions Inc, 386 Watline Ave, Mississauga,
Ontario, Canada, L4Z 1X2). The data obtained are summarized
in Table 1.
2.2. Mineralogical and geochemical studies
According to (Ibrahim, Saleh, Rashed, & Watanabe, 2007;
Darwish, 2013), the Abu Rushied rock units are characterized
by an economically poly-metals mineralization especially the
uraniumminerals (uraninite, kasolite, uranophane andmeta-
autunite), thorium minerals (thorite and uranothorite) and
niobiumetantalum mineral assemblage. Also the accessory
minerals recordedwithin the studied rock varieties are zircon,
monazite, cassiterite, pyrite and fluorite.
The cataclastic rocks and lamprophyres in Abu Rushied
area are mainly affected by the diagenetic and hydrothermal
alteration respectively. The geochemical distribution of trace
elements revealed that, the rocks are mostly enriched in U,
Th, Nb, Pb, Y, Zr, Zn, Ga, Cu, Sr and Rb (Saleh et al., 2013).
The preliminary estimation of average ore grade (%) of
uranium mineralization and rare metals in cataclastic rocks
are; U (0.067%), Th (0.0669%), Nb (0.22%), Y (0.1725%), Zr
(0.353%), Pb (0.27%), Zn (0.1725%), Ga (0.009%) and Cu (0.029%)
(Ibrahim et al., 2007).
3. Uranium exploration in the area
The uranium exploration techniques have serious concen-
tration for deeply buried and/or remobilized uranium ore
bodies. For such deposits extensive drilling and complicated
instrumentation are required, which makes the venture very
expensive (Fleischer and Mogro-Comero, 1981).
The exploration techniques based on gamma measure-
ments are ineffective when target is deep mineralization or
when there has been remobilization of ore. Also, these
methods are expensive and time consuming.
On the other hand, methods based on radon measure-
ments provide a potential opportunity to locate uranium de-
posit buried hundred meters deep without involving
expensive equipment, time consuming and much finance
(Qureshi, Samad Beg, & AhmedKhan, 1988).
Random movement of the radon atoms, in soil, air space
and rock fractures result in the migration of radon atoms
along the concentration gradient, which is known as diffusion
in a molecular basis. The concentration gradient and the flux
of the radon atoms is linked to D and is described by Fick's law(Crank, 1975)
Jb ¼ �DbvCvx
Or (1)
Je ¼ �DevCvx
Or (2)
Where J is the activity flux densitymeasured in Bq/m2s and
x is the one dimensional direction into the soil. As the diffu-
sion process arises in the opposite direction of the increasing
concentration so, the negative sign is arises (Khan, Varshney,
Parsed, Tyagi, & Ramachandran, 1990).
Fig. 1 e Detailed geologic map of Abu Rushied area, South Eastern Desert (Ibrahim et al., 2004).
J o u r n a l o f R a d i a t i o n R e s e a r c h and A p p l i e d S c i e n c e s 8 ( 2 0 1 5 ) 5 6 2e5 6 9564
De, effective diffusion coefficient, relates the interstitial
concentration to the flux density across pore area, Je.
Db bulk diffusion coefficient relates the interstitial con-
centration of radon to the flux density across a geometric area,
Jb.The relation between them is written as Db ¼ εDe where ε is
the total soil porosity (Nazaroff, Moed, & Sextro, 1988).
Table 1 e Radiometric levels of Uranium and Thorium.
Zone eU ppm eTh ppm
Very low <2 <5Low 2e8 5e30
Medium 8e25 39e80
High 25e200 80e300
Very high >200 >300
3.1. Determination of subsurface radioactive depositsusing alpha track CR-39 detector
In this case, the diffusion process of radon in a cylinder of
65 cm length and 7 cm in diameter has been determined by
radon concentration gradient across the cylindrical chamber
(Fig. 2 a & b). The fig. a, shows how the tube was fixed in the
Lithology
Wadi deposits and ophiolitic m�elange
Mylonitic two mica granite
Ultracataclastic Cataclastic rocks
Cataclastic & protocataclastic
Mineralized zone
Silicified ultracataclastic
J o u rn a l o f R a d i a t i o n R e s e a r c h and A p p l i e d S c i e n c e s 8 ( 2 0 1 5 ) 5 6 2e5 6 9 565
measuring station, while fig. b, showing in details the ar-
rangements of the solid state nuclear track detector type CR-
39 inside the diffusion chamber (tube).
Radon transported to the surface detector chamber mainly
by diffusion and dispersion process as from the point of origin
following alpha-decay of 226 Radium atoms from the under-
ground rock surface. In this case the diffused radon can be
measured using a group of CR-39 detector sets presented at
different heights from surface boundary. It is typically
assumed that radon flow is due to pressure e driven flow in
enclosed chamber. After 10 days the detectors were collected
and etched at the optimum conductions 6.25 Normal NaOH,
70 �C and 8 h for etching time (Malmqvist & Kristiansson,
1980), then dried and counted using an optical microscope of
magnification 400�. The track density was converted to radon
concentration in Bq/m3using priveously determined calibra-
tion factor (Said et al., 2009).
When radium atom decays to radon, the energy generated
is strong enough to move the radon atom at a distance about
40 nm, this is known as alpha recoil (Aly et al., 2012). For a
radon atom to escape from the soil grain, the radium atom
must be within the recoil distance from the grain surface
(which varies somewhat depending on the density of the
material) and direction of recoil must move the radon atom
towards the outside of the grain.
DRock*XRock ¼ DAir*XAir (3)
In this work, a detector chamber for studying radon diffu-
sion has been developed and applied to estimate the radio-
activity risk for location, containing various unknown
amounts of radionuclide. By drawing curves between the
radon gas concentration at y-axis and distance of the detector
from the contact layers in cm at x-axis
The slope of the obtained curves can be represented by the
following equation
CRn ¼ ax2 þ bxþ c
By differentiating the above equation to get the maximum
concentration gradient, we get
Fig. 2 e a) Cylinder fixed on trench No.
vCvx
¼ aXþ C (4)
Equaling this value by zero, to get the inversion point of the
curve, maximum value, then vCvx ¼ 0 and hence the value of X Air
was then calculated.
Since the radon diffusion coefficient in air is
Dair ¼ 1.2*10�5 m2s�1., and by deducing the values of the
diffusion coefficient of the rock type under investigation then
the value of the Drock was then obtained. In general this value
in soil generally ranges (10�8e10�5 m2s�1).
Finally the depth of the ore deposit XRock can be calculated
in meter from equation;
XRock ¼ ðDAir*XAirÞ=DRock (5)
Table 2 represent some measured values for the effective
radon diffusion coefficient De(m2s�1) for some porous
materials.
3.1.1. Geological features of the studied trenchTheUTM location for the studied trench is (678967, 2725249) it is
located along Khour Abalea in the southern part at periphery of
Wadi Abu Rushied contacted m�elange rocks (Fig. 2). The di-
mensions of this trench are 1.4 (face) � 4.4m (left wall) � 2m
(Right wall) and total excavated rocks are 13 m3. The geological
rock units within the trench aremainly fine tomediumgrained
cataclastic rocks. The common sets of joints dissecting the
cataclastic rocks are NNW-SSE and ENE-WSW trends The
hematitization and silicification processes are the common
alteration process in this trench. Visible uranium mineraliza-
tion is associated with the hematitization and Mn, Cu-
mineralization indicating hydrothermal solution origin. The
mineralization is found as fine grains coated the joints and
fractures planes. The high readings are recorded in this trench
associatedwith cataclastics especially at the southof right limb.
The ranges of the spectrometric measurements in the trench
including (face, floor and right limbs) are shown in Table 3.
Fig. 3 shows the geological map as well as, Dose rate
(nSvh�1), K (%), eU (ppm) and eTh (ppm) concentration for the
studied trench.
T-28. b) Radon diffusion chamber.
Table 2 e Effective diffusion coefficient for radon inunconsolidated soil materials and concrete (Nazaroffet al., 1988).
Porous material Effective radon diffusioncoefficient, De(m
2s�1)
Compacted silty sands (3.0 ± 1.3)� 10�6
(3.2 ± 1.5)� 10�6
Compacted clay sands (2.5 ± 1.0)� 10�6
Compacted inorganic clays 2.7 � 10�6
2.5 � 10�7
Silty sandy clay 6.0 � 10�8
(5.4e7.2)� 10�6
Uranium mill tailings 8 � 10�7
Loams 5.7 � 10�10
Mud (1.1e4.0)� 10�7
Concrete 1.2 � 10�8
3.4 � 10�8
3.3 � 10�8
(0.8e8.4)� 10�8
Other materials e
Brick (0.8e3.0)� 10�7
Gypsum (1.0e4.0)� 10�6
Granite 0.053 � 10�6
Polymer concrete PCC <10�6
limestone 0.34 � 10�6
J o u r n a l o f R a d i a t i o n R e s e a r c h and A p p l i e d S c i e n c e s 8 ( 2 0 1 5 ) 5 6 2e5 6 9566
3.2. Rn- gas concentration measurements usingcylindrical tube technique
A hard plastic tube of 65 cm length and 7 cm in diameter was
used (Fig. 3b). The measurements were done during summer
season; the tube was fixed tightly at the top of the bore hole
between the radon source (radium ore presented at the tested
location) and the surrounding air. Radon inflow (which
occurred from deeply buried deposits) canmigrate to the used
cylindrical chamber. The detectors (eleven) were mounted
and fixed in the tube at different heights 5 cm between each
two detectors. The structure of the passive dosimeter was
described by several workers (Hafez, Hussein, & Rasheed,
2001; Aly et al., 2012). The tube was then immersed on the
ground which contains uranium and radium source. The
alpha particles emitted due to the presence of radon were
recorded by the solid detectors. After an exposure time of 10
days the detectors were then collected, etched under the
Table 3 e Spectrometric measurements of the studiedtrench, Abu Rushied area.
Dose rate (Gy/h) K% eU(ppm) eTh(ppm)
Floor
Min. 2100 5.3 124 364
Max. 4100 8.1 330 732
Aver. 2957 6.9 185 505
Right limb
Min. 715 3.6 61 65
Max. 6200 8.3 479 903
Aver. 2013 5.85 152 282
Face
Min. 878 4.1 84 80
Max. 3500 7.8 295 531
Aver. 2162 5.71 154 330
previously mentioned optimum conditions and then counted
under optical microscope of magnification 400�. The track
density was converted into radon gas concentration in Bq/m3
using the calibration factor previously mentioned.
Radon gas concentration calculations: The radon gas con-
centration (Bq.m�3) at each monitoring station can be calcu-
lated from the formula (Qureshi et al., 1988; Malmqvist &
Kristiansson, 1980).
CRn
�Bq:m�3
� ¼ r
K(6)
Where (r) is the corrected track density (number of tracks
per cm2), (K) ¼ 0.2217 ± 0.035 (Said et al., 2009), is the cali-
bration factor ((tracks. cm2.d�1). (pCi/l)�1). The radon con-
centrations in KBq.m�3 were calculated by using the relation:
C�KBq
�m3
� ¼ 0:037*CPðPCi=LÞ (7)
The obtained results were presented in Table 3, from these
data we can get that; the diffusion of radon is markedly
exponentially changed as height from the boundary surface;
the effect of weathering conditions is evaluated in field of
experiments to be neutral pressure and neutral temperature
350C in summer time. The recorded track density (and hence
radon concentration) is decreased by increasing the height
from the source until a certain height (40e45 cm), then
increased again until 50 cm height after that it decreased
again till 60 cm.
3.3. Exhalation rate measurements
The same configuration as described above in Fig. 2b was used
formeasuring the exhalation rates in (Bqm�2 h�1). In this case
the exhalation rates were measured from the obtained date
for the recorded track densities on the exposed detector sur-
faces, by considering that the exposed tube is a cylinder of
radios (d) 7 cm and height h¼ 10,15,20,25,30,35,40,45,50,55and
60 cm, respectively.
The lower sensitive part of the detector was exposed freely
to the emergent a-particle due to radon decay from the sam-
ples in the can (tube) so that it could record it. The exhalation
rate of radon is obtained from the expression (Khan, Prasad,&
Tyagi, 1992).
Ex ¼ CVlA½Tþ 1=lðe�lt�1Þ� (8)
Where
Ex ¼ radon exhalation rate (Bq m�2 h�1).
C ¼ the measured values for the integrated radon exposure as
measured by CR-39 detector (Bq m�3) in Table 3,
V¼ effective volume of the can (m3);
l ¼ decay constant for radon (h�1);
T ¼ exposure time (h) and
A ¼ area of the can (m2).
4. Results and discussions
i) For track density and radon concentration: Table 4. Shows
the measured track density (Track density/cm2/day) as
Fig. 3 e View showing the geological map as well as, Dose rate (nSvh¡1), K (%), eU (ppm) and eTh (ppm) concentration map
for the studied trench, Abu Rushied.
J o u rn a l o f R a d i a t i o n R e s e a r c h and A p p l i e d S c i e n c e s 8 ( 2 0 1 5 ) 5 6 2e5 6 9 567
obtained from the exposed detectors at different height as
well as the calculated values for the radon concentration
using equation (6) From the table we can get that: the
recorded track density decreases as the height of the de-
tector from the surfaces increases until it reaches a
smallest value then increases again.
ii) Depth of the subsurface radioactive anomalies
Table 5 shows the average track density for the studied
trench after omitting the last four points from the table in
which the readings increased and again decreased indicating
two layers of anomalies.
From Fig. (4) we get:
CRn ¼ 0:126x2 � 10xþ 231:5 (9)
dc=dx ¼ 0:252x� 10
dc=dxðx ¼ 0Þ¼ 39:683 (10)
Table 4 e Values of track density/cm2/day and Rn gasconcentration Bq/m3.
Distance/cm Trackdensity/cm2/day
Rn gasconcentration Pci/l
10 36.5 ± 5.76 146.1 ± 23.06
15 26.29 ± 4.9 105.3 ± 19.62
20 21.05 ± 3.27 84.28 ± 13.09
25 15.56 ± 3.12 62.3 ± 12.49
30 10.94 ± 1.96 43.8 ± 7.848
35 9.07 ± 2.27 36.32 ± 9.089
40 6.13 ± 1.06 24.54 ± 4.244
45 5.23 ± 1.69 20.94 ± 6.767
50 3.92 ± 1.28 15.7 ± 5.125
55 5.18 ± 2.19 20.74 ± 8.769
60 3.95 ± 1.33 15.82 ± 5.325
Where C is the radon concentration, X is the depth of the
rock. The radon concentration variation stop at path length of
radon movement into air, from equation (dc/dx second) we
get;
Xair ¼ 39.683 cm
Since
DRock*XRock ¼ DAir*XAir
Where, XRock is the depth of the source of radioactivity in
natural rock
For the studied trench
DRock ¼ ðDAir*XAirÞ=XRock
¼ ð1:2*10�2ðmÞ*39:683*10�2ðm��0:053*10�6ðm=sÞ
DRock ¼ 89:847 meter(11)
(Case two):
From the obtained data for the Rn gas concentration and
the distance of the detector from the ground as Table 4 we can
get the equation that describes the radon gas concentration
gradient, From the obtained data for the Rn gas concentration
and the distance of the detector from the ground as Table 4,
we can get the equation that describes the radon gas con-
centration gradient. This is accomplished by drawing a curve
which describes this relation between radon concentration
Table 5 e Values of Track density/cm2/day and Rn gasconcentration Bq/m3(after cutting)Trench 28.
S.No Track density/cm2/day Rn gas concentration Pci/l
10 36.5 ± 5.76 146.1 ± 23.06
15 26.29 ± 4.9 105.3 ± 19.62
20 21.05 ± 3.27 84.28 ± 13.09
25 15.56 ± 3.12 62.3 ± 12.49
30 10.94 ± 1.96 43.8 ± 7.848
35 9.07 ± 2.27 36.32 ± 9.089
Fig. 4 e Rn concentration gradient for the studied trench (case one).
J o u r n a l o f R a d i a t i o n R e s e a r c h and A p p l i e d S c i e n c e s 8 ( 2 0 1 5 ) 5 6 2e5 6 9568
and the distance of the detector from the contact layer (see
Fig. 5).
CRn¼ 0:075x2 � 7:605xþ 208 (12)
By differentiating the above equation to get the maximum
concentration gradient we get;
vCvx
¼ 0:15x� 7:605 (13)
Equaling this value by zero, then
vCvx
¼ 0 (14)
Then 0.15x ¼ 7.605
X ¼ 7.605/0.15
X ¼ 50:7 cm (15)
This value is called Xair
Where C, is the radon concentration, X is the depth for the
rock. The radon concentration variation stop at path length of
radon movement into air, from equation (dc/dx second) we
can get
Fig. 5 e Rn concentration gradi
Xair ¼ 50:7cm (16)
Where
Xairis the distance that traveled by radon in air. The diffused
concentration decreases exponentially with the increase of soil
thickness (Shweikani, Giaddui, & Durrani, 1995).
DRock*XRock ¼ DAir*XAir (17)
Where, XRock is the depth of the source of radioactivity in natural
rock.
For the studied trench
DRock ¼ ðDAir � XAirÞ=XRock
¼ ð1:2 � 10�2ðmÞ � 50:7 � 10�2ðmÞ�0:053 � 10�6ðm=sÞDRock ¼ 114:79meter
(18)
The above two results obtained from case 1 and case 2,
reflecting that, the thickness layer of the rock bearing ura-
nium deposits are nearly 25 m.
4.1. Exhalation rate mBqm�2s�1
Table 6 presents the measured values for exhalation rate
(mBqm�2h�1) of the studied trench which, from the table we
get that the exhalation rates were ranges between 6.14E-03 at
ent for the studied trench.
Table 6 e Values of Track density/cm2/day and Rn gas concentration Bq/m and Exhalation rate.
S.No High from ground(cm) Rn gas concentration Bq/m3 Volume in m3 Exhalation ratemBqm�2h�1
1 10 146.1 ± 23.06 0.0004 4.53E-02 ± 7.15E-03
2 15 105.3 ± 19.62 0.0006 3.57E-02 ± 6.65E-03
3 20 84.28 ± 13.09 0.0008 3.00E-02 ± 4.66E-03
4 25 62.3 ± 12.49 0.001 2.29E-02 ± 4.58E-03
5 30 43.8 ± 7.848 0.0012 1.64E-02 ± 2.94E-03
6 35 36.32 ± 9.089 0.0013 1.38E-02 ± 3.46E-03
7 40 24.54 ± 4.244 0.0015 9.44E-03 ± 1.63E-03
8 45 20.94 ± 6.767 0.0017 8.13E-03 ± 2.63E-03
9 50 15.7 ± 5.125 0.0019 6.14E-03 ± 2.00E-03
10 55 20.74 ± 8.77 0.0021 8.16E-03 ± 3.45E-03
11 60 15.82 ± 5.33 0.0023 6.25E-03 ± 2.11E-03
J o u rn a l o f R a d i a t i o n R e s e a r c h and A p p l i e d S c i e n c e s 8 ( 2 0 1 5 ) 5 6 2e5 6 9 569
h¼ 50 cm and 4.53E-02 at h ¼ 10 cm, with increase at lower
positions (small volume) and decreasing at higher positions
(large values). The obtained values are comparable with that
recorded for the granite type of rock (Ching Jiang, Pao Shan, &
Tieh Chi, 1993).
r e f e r e n c e s
Aly, H. A. S., Hegazy, T. M., Abdel-Ghany, H. A., Abu-Zied, H. M.,EL Aassy, I. E., & Shaaban, D. H. (2012). Determination ofsubsurface radioactive anomalies using alpha particlemeasurements of diffused radon. Isotope & Radiation Research,44(1), 89e101.
Anjos, R. M., Umisedo, N., da Silva, A. A. R., Estellita, L.,Rizzotto, M., Yoshimura, E. M., et al. (2010a). Occupationalexposure to radon and natural gamma radiation in the LaCarolina, a former gold mine in San Luis Province, Argentina.Journal of Environmental Radioactivity, 101, 153e158.
Anjos, R. M., Veiga, R., Macario, K., Carvalho, C., Sanches, N.,Bastos, J., et al. (2006). Radiometric analysis of Quaternarydeposits from the southeastern Brazilian coast.Marine Geology,229, 29e43.
Bossew, P. (2003). The radon emanation power of buildingmaterials, soils and rocks. Applied Radiation and Isotopes, 59,389e392.
Ching Jiang, C., Pao Shan, W., & Tieh Chi, C. (1993). Radonexhalation rate from various building materials. Health Physics,64, 613e619.
Chyi, L. L., Chou, C. Y., Yang, F. T., & Chen, C. H. (2002). Geofis. Int,41, 507.
Crank, J. (1975). The mathematics of diffusion. Oxford: ClarendonPress.
Darwish, M. E. (2013). Petrologenesis and mineralogicalcharacterization of pegmatites from Khour Abalea, South EasternDesert, Egypt (in press).
Estellita, L., Santos, A. M. A., Anjos, R. M., Yoshimura, E. M.,Velasco, H., daSilva, A. A. R., et al. (2010). Analysis and riskestimates to workers of Brazilian granitic industries andsandblasters exposed to respirable crystalline silica andnatural radionuclides. Radiation Measurements, 45, 196e203.
Fleischer, R. L., & Mogro-Comero, A. (1981). Radon Transport in theEarth, a tool for uranium exploration and earthquake prediction.General Electric Report 81 CRD 208.
Gingrich, J. E. (1984). Radon as geochemical exploration tool.Journal of Geophysical Exploration, 21, 19e39.
Hafez, A. F., Hussein, A. S., & Rasheed, N. M. (2001). AppliedRadiation and Isotopes, 54, 291e298.
Ibrahim, I., Saleh, G. M., Amer, T., Mahmoud, F., Abu El-Hassan, A., Ali, M., et al. (2004). Uranium and associated raremetals potentialities of Abu Rusheid brecciated shear zone II, southEastern Desert, Egypt. Cairo, Egypt: Nuclear Materials Authority.
Ibrahim, M., Saleh, G., Rashed, M., & Watanabe, K. (2007). c: Basemetal mineralization in lamprophyre dykes at Abu Rusheid area,south Eastern Desert, Egypt (pp. 31e40). The 10th Inter. Min.Petrol., and Metall. Eng. Conf., Assuit Univ.
Khan, A. J., Prasad, R., & Tyagi, R. K. (1992). Measurement of radonexhalation rate from some building materials. Nuclear Tracksand Radiation Measurements, 20, 609e610.
Khan, A. J., Varshney, A. K., Parsed, R., Tyagi, R. K., &Ramachandran, T. V. (1990). Nuclear Tracks and RadiationMeasurements, 17, 497e502.
King, C. (1980). Episodic radon changes in subsurface soil gasalong active fault and possible relation to earthquakes. Journalof Geophysical Research, 85(B6), 3065e3078.
Malmqvist, E. L., & Kristiansson, K. (1980). Measuring radon belowground level. Swedish Patent 007, 337, 801, 020.
Nazaroff, W., Moed, B. A., & Sextro, R. G. (1988). In W. Nazaroff, &A. Nero (Eds.), Radon and its decay products in indoor air (p. 60).John Wiley and Sons, Inc.
Planinilc, J., Radolilc, V., & Lazanin, Z. (2001). Applied Radiation andIsotopes, 55, 267.
Qureshi, A. A., Samad Beg, M. A., Ahmed, F., & Khan, H. A. (1988).Uranium exploration in Pakistan using alpha sensitive plasticfilm.Nuclear Tracks and RadiationMeasurements, 15(1e4), 735e739.
Said, A. F., Hassan, S. F., Orabi, F. M., Abdel Razek, Y. A.,Mahmoud, M. A. M., & Ibrahim, I. H. (2009). Uranium Prospectingusing CR-39 Etch track detector at Abu Rusheid Area, South EasternDesert, Egypt. internal report NMA.
Saleh, G. M., Mahmoud, F. O., Abu El Hassan, A. A., Rashed, M. A.,Khaleal, F. M., Mahmoud, M. A., et al. (2013). Mineral resourcesestimations in the cataclastic rocks of Abu Rusheid area, SouthEastern Desert, Egypt (Internal report).
Shweikani, R., Giaddui, T. G., & Durrani, S. A. (1995). RadiationMeasurements, 25, 581e584.
Singh, S., Sharma, D. K., Sunil, D., & Randhawa, S. S. (2006).Geological significance of soil gas radon: a case study ofNurpur area, district Kangra, Himachal Pradesh, India.Radiation Measurements, 41, 482e485.
Steinitz, G., Piatibratova, O., & Kotlarsky, P. (2011). Possible effectof solar tides on radon signals. Journal of EnvironmentalRadioactivity, 102, 749e765.
Veiga, R., Sanches, N., Anjos, R. M., Macario, K., Bastos, J.,Iguatemy, M., et al. (2006). Measurement of naturalradioactivity in Brazilian beach sands. Radiation Measurements,41, 189e196.