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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

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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).

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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).

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