• No results found

Measurements of Natural Radio activity Levels and Associated Health Hazard Indices in Some Portland Types of cement, Ethiopia

N/A
N/A
Protected

Academic year: 2020

Share "Measurements of Natural Radio activity Levels and Associated Health Hazard Indices in Some Portland Types of cement, Ethiopia"

Copied!
9
0
0

Loading.... (view fulltext now)

Full text

(1)

www.ijsred.com

Measurements of Natural Radioactivity Levels and

Associated Health Hazard Indices in Some Portland

Types of cement,

Ethiopia

Hailu Geremew

1

*, A. K. Chaubey

1

and Birhanu Turi

2 1Department of Physics, Addis Ababa University,

Addis Ababa, Arat kilo, Ethiopia

2Ethiopian Radiation Protection Authority (ERPA)

Addis Ababa, Ethiopia

*Email-

hailu.buze@gmail.com

---

************************

---

Natural radioactive materials are present everywhere in the environment by nature. Using environmental raw materials in factories can produce final products with naturally radioactive materials. The natural radioactivity and hazard indices like radium equivalent activity, absorbed dose rate, annual dose rate, external and internal hazard indices due to long-living radioactive materials, 238U, 232T h and 40K can be measured using gamma spectrometer. In this work, levels of natural radioactivity in intermediate products (clinker) and end products of cement were measured using a gamma-ray spectrometer with an HPGe detector. The specific radioactivity of 238U,232T h

and 40K in the analyzed intermediate and final products of cement samples were ranged from

20.53Bq/kg to 36.42Bq/Kg, 18.84Bq/kg to 45.87Bq/Kg and 101.96Bq/kg to 369.71Bq/Kg

respectively. In the same way, maximum hazard indices for radium equivalent activity, absorbed dose rate, annual dose rate, and external and internal hazard indices were measured as 118.79Bq/Kg,

54.67nGy/hr, 0.067mSv/yr, 0.32 and 0.40 respectively in PPC sample. These values are below the recommended levels and consistent with the results of other investigations in different parts of the world.

Keywords Activity, Cement, Clinker, Dose rate, Gamma spectrometry, Portland Cement, Radioactive materials.

---

************************

---

I. INTRODUCTION

Radiations from natural radionuclide and other sources are known as background radiation and it is a source of continuous exposure to human beings and the environment. The background radiation can be elevated if the environment is polluted either from man-made or natural activities like weathering [1]. Building materials, like cement, may contain various amounts of

background radiations, like cosmic background and primordial background which are originated from different atmospheric layers and Earth’s crust [2]. The cosmic background radiations which may happen in

(2)

www.ijsred.com

uranium (238U), thorium (232T h) and their decay products, and the radioactive isotope of potassium

(40K). The two sources of background radiations in cements can contribute to environmental radioactivity mainly in two ways, external and internal exposure. The external radiation exposure is caused by gamma radiation originating from (226Ra),

(232T h) and their progenies, a nd (40K). However,

the internal radiation exposure is due to the short-lived daughter product of radon (222Rn) a f t e r the decay of radium, (226Ra). This can be permanent sources of internal radiation by sticking and accumulating themselves in respiratory trucks and lung respectively. During inhalation, a part of (222Rn) may decay to (218P o) which sticks to the respiratory trucks and becomes a permanent source of internal radiation [2–4].

There has been an increasing demand for cement throughout the world due to the increase in human civilization. In the present study, the analyzed samples are mainly of Ordinary Portland Cement (OPC), Pozzolana Portland cement (PPC) and semi-processed cement called Clinker of brands seen in fig: 1. These were collected from the open market in the capital city, Addis Ababa (PPC of Derba and Mosobo cement) and from three cement factories, Mugher, Dangote and Habesha in West Shoa, Ethiopia.

(a) Mugher cement (b) Dangote cement

(c) Habesha cement (d) Mosobo cement

Figure 1: Brands of collected cements

and clinker samples from open markets and factories.

The products of these five (5) factories covers almost all parts of the country and exported to some of the neighbor countries, like Kenya, Somali and others. There are also other cement factories in the country, and all of them are producing Portland types of cement which are a basic ingredient of concrete, mortar, stucco and the like as construction materials [5]. In factories, cements are made from grinded clinker and some additive raw materials. Clinker is made by burning a mixture of limestone, clay, and sandstone at high temperatures, (1,3000C), [6], and additive raw materials are volcanic ash and gypsum, to increase the quantity and adhesive properties of the final products. All, the main and additive raw materials are from the earth crust that may contain fragments from igneous and metamorphic rocks. Such rocks are rich in radioactive materials and can be a factor for the presence of radioactive materials in types of cement. Additive raw materials, like volcanic ash and mica containing materials, are also rich in long-living radioactive nuclide and these can also increase the concentrations of radioactive materials in cement’s final product [5].

Therefore, keeping in view the natural risk of radiation, it is necessary to measure the natural environmental radiation levels and this study will measure the radiation levels in types of cement and semi-processed types of cement used for making of dwellings and other constructions. Samples of study were collected from the market in the capital city, Addis Ababa, and from Mugher, Dangote, Habesha, cement factories in Ethiopia. We also measured radioactivity of intermediate product, clinker, from the three factories. Gamma spectrometry based on HPGe was the spectrometer used to measure levels

of radio activities for 238U, 232U and 40K. Associated radiological hazard indices like radium equivalent activity, Internal hazard index, absorbed dose rate, and external hazard index, etc. were calculated from the measured activities. The results of concentration levels and radiological hazard indices obtained in this work were compared with similar studies carried out in other countries.

II.MATERIALS AND METHODS

(3)

www.ijsred.com

We collected samples of study, OPC, PPC and Clinker from the market, and three factories, Mugher Cement Factory (under chemical industry) Gov., Dangote Cement Factory (Ethiopia branch) Plc., and Habesha Cement Factory, SC, in West Shoa, Oromia regional state, Ethiopia. These factories are found in the north-western direction of the capital city, Addis Ababa, at distances of 90-KM, 83-KM, and 40-KM respectively as seen in fig: 2.

(a) The north-western direction of the Sampling area from AA.

(b) Cement at market (c) Mugher Cement Factory, Gov.

(d) Dangote cement (e) Habesha cement factory factory, Ethiopia

Figure 2: OPC, PPC, and Clinker sampling areas

Portland Cement (PC) is a finely grinded, soft, powdery-type substance, mainly used to bind fine sand and coarse aggregates together in concrete. PC can be named by different names based on the grade given for them on their pressure resisting strength. We used Ordinary PC and Pozzolana PC which is graded as 42.5N and 32.5N respectively. This is from rising

or lowering the amount of limestone (CaCo3) added as the main raw material, which means more limestone will take to OPC and other higher grade types of cement-like 52.5N, and low limestone will produce PPC and any other lower grade types of cement [7]. The intermediate product, clinker, is a mixture of limestone, sandstone, and clay according to the information we gathered from a factory laboratory group. These raw materials are mixed according to the cement grade they want to produce, and heated

by more than 1, 3000C.

b. Sampling and Sample preparations

A total of eleven (11) samples of study (OPC, PPC, and Clinker) had been collected fro m market and cement factories. The samples had been brought to Addis Ababa University nuclear physics laboratory by packing in polyethylene bags and

oven-dried to 600C to avoid moisture. The clinker samples were grinded to a fine powder to the optimum size of heavy minerals. This is helpful for the

reduction of self-absorption and sealed in

polyethylene bags seen in Fig. 3a, until we set Marinelli beakers.

(a) Packed samples (b) Sealed samples

Figure 3: Prepared samples for gamma

spectrometer measurement

(4)

www.ijsred.com

progeny [8, 9]. Finally, the samples were counted for 10-hours, compared with the measured standardized soil sample of the same geometry in the same conditions.

c. Experimental Setup and Measurements

The measurements were performed using p-type high purity germanium (HPGe) coaxial detector with a relative efficiency of 77% and a multichannel analyzer of 8192 channel performance.

Figure 4: HPGe-detector and its shielding (Pb+Cd+Cu)

To minimize the number of photons whose their sources are out of a sample of the study, a detector is covered in a lead of 100-mm thickness, cadmium of 2-mm thickness, and copper of 2.5-2-mm thickness, as tried to visualized in Fig. 4.

The 100 mm thick lead is used to reduce soft components of cosmic rays to a very low level. The copper layer suppresses the X-ray emitted from the lead (especially wi th energy 73.9 keV), by its interaction with external radiation. The cadmium layer absorbs thermal neutrons produced by an interaction of cosmic ray (Photo-neutron and alpha-neutron sources near Lab. set up). There is also an effect of scattered radiation from shielding materials. This can be controlled by fixing the detector at the center of the shielding materials itself. After fixing all, we connected the detector to an electronic circuit,

Figure 5: HPGe gamma spectrometer with DAC

Electronic circuits (ERPA Lab.

like a pre-amplifier, amplifier, analog to digital converter to set computer-user interface medium, so that we can see an output spectrum on a computer screen as tried to display in Fig.5.

The background radiation was also measured for an empty Marinelli beaker with the same counting time, and the effects of background radiation were subtracted from sample spectra [10, 11].

The spectra were analyzed for energies of 911 keV of

228Ac for 232Th radionuclide investigation, 351 keV

of 214Pb and 609 keV of 214Pb for 238U radionuclide investigation, and 1460.9 keV gamma energy for 40K activity concentration. Our set up reports more than 99% confidence for the existence of these photo peaks exactly at channel number used in calibration. Energies 238 keV, of 212P b and 727 keV, of 212Bi were not observed in the region of the spectrum according to our calibration data. Calibration of experimental set up was done using IAEA certified standard sources and points were seen on a straight line as seen from Fig. 6 [12]

Figure 6: Calibration curve by standard check sources in the region of interests.

After calibration, absolute efficiency of the detector was measured using the same standard sources for the same geometry as in eq: 1

ℰ =

(5)

www.ijsred.com

Where Ai is net peak area corresponding to Ei, Ci is deduced activity by certified radionuclide, Iγ indicates the probability of Ei photon emission per decay, and t is counting time. The efficiencies of energies used for activity investigation also coincide with the efficiency curve seen in Fig. 7.

Figure 7: Efficiency curve measured by the certified standard sources in the region of interest.

Following information that represents Uranium, Thorium, and Potassium, from the experimental output, activity was calculated according to eq: 2. The specific activity, CEi,(in Bq/kg) of a nuclide i for a photopeak at energy E, after rearranging eq: 1, is given by; [13]

=

ℰ ∗ ∗ ∗ ...(2)

d. Radiological Hazard Assessment

Exposure of the population to environmental radiation sources increases appreciably as industries and natural disasters increase. Therefore, it is important to assess the radiological risks of radiation sources from environments like building materials and buildings. The widely used radiation hazard indices for assessment are radium equivalent activity, absorbed dose rate, annual dose rate, internal and external hazard indices and other parameters that give information about radiation exposure to the population.

Radium Equivalent Calculation (Raeq )

A gamma radiation hazards caused by specific radionuclides found in our samples were evaluated using different indices. (Raeq), is the weighted sum

of activities of the three radionuclides based on the

supposition that 370Bq/kg of 238U, 259Bq/kg of 232T h, and 4810Bq/kg of 40K will produce the same gamma-ray dose rate. Therefore Raeq can be calculated from this concept as; [14]

Req=CRa+1.43CTh+0.077CK ...(3)

where CU, CTh and CK are activity concentrations

in Bq/Kg of 238U, 232T h and 40K respectively.

Absorbed Dose Rate in Air (DR)

This parameter, (DR) is measured at a distance of 1m above the surface that ensures a uniform distribution of the three radionuclides for almost the same activities. At this distance the absorbed Dose rate (DR) can be calculated as,

DR = 0.427CU + 0.623CT h + 0.043CK...(4)

Where the dose rate, DR is in nGy/h and C is

activity in Bq/Kg for U-238, Th-232, and K-40.

This dose rate indicates the received dose at outdoors

from radiation emitted by a radionuclide in

environmental materials. The limit for this dose is 59nGy/h [14, 15].

The Annual Effective Dose Rate (ADR)

An annual effective dose rate can be calculated to assess the health effects of the absorbed dose in a year. Mathematically it can be represented as;

ADR = DR(mGy/h) * 8760h/y * 0.2 * 0.7Sv/Gy

* 10−6...(5) where ADR is in mSv/y and 0.7SvG/y is to transform absorbed dose in the air to the effective dose received by humans at 1m hight, 0.2 is an outdoor occupancy of 20% and 80% for the indoors [9, 14]. This factor may be changed according to the patterns of life in the study area. The worldwide average annual effective dose is approximately 2.4mSv/y [14, 15].

External(Hex)and Internal(Hin) Hazard Index

The external radiation hazard index, Hex, corresponding to the investigated radionuclides is calculated using the following equation;

=

(6)

www.ijsred.com

The maximum value of Hex should be 1 corresponding to the maximum value of Raeq , which is 370Bq/Kg.

The hazard levels from the inhalation of alpha

particles emitted from the radon short-lived

radionuclides such as 222-Rn, the daughter product of 226-Ra, and 220-Rn, the daughter product of 224-Ra, can be quantified by the internal hazard index, Hin as; [16].

=

"! /

+

/

+

!" / . . . ( 7 )

III.

Results and Discussion

From the collected and prepared samples of Portland types of cement, spectra of each were recorded by using the HPGe detector cascaded with the necessary electronic devices. From the observed spectra, energies representing daughters of long-living radioactive materials and direct representing energy were identified.

Table 1: Activity concentrations of natural

radionuclides in Bq per Kg for Portland types of cement and Clinker samples, M for Mugher, D for Dangote and H for Habesha cement factory.

The activity concentration of 238U, 232T h and 40K in partially processed and final products of Portland cements presented in the table above shows

below the world average values given for building materials, 50Bq/Kg, 50Bq/Kg and 500Bq/Kg respectively [17]. To the environment, the certified world natural radioactivity concentration limit is

30Bq/Kg, 35Bq/Kg and 400Bq/Kg for 238U, 232T h and 40K respectively. Some of the activity concentrations measured in the collected samples crossed the permissible environmental activity values.

Figure 8: HPGe output Spectrums from some of the sample

Clinker, the partially processed Portland cement is a mixture of limestone, sa ndst one and clay rock after

heated by a temperature around 13000C. Therefore, the natural radioactivity concentration in clinker samples is the same as in the three main raw materials, lime, sand and clay. Out of these raw materials, the first two are under the category of sedimentary rock in which concentrations of the three natural radioactive materials are low [18,

ample Code

Sample Name

238U Bq Kg

232T h Bq Kg

40K Bq Kg

M01 Clinker 36.42 ± 1.51 32.19 ± 1.56 149.78 ± 6.68

M02 OPC 34.34 ± 1.65 31.18 ± 1.59 172 ± 7.98

M03 PPC 31.63 ± 1.46 39.49 ± 2.00 369.71 ± 16.94

D04 Clinker 22.58 ± 0.85 19.62 ± 0.98 101.96 ± 4.67

D05 OPC 20.53 ± 0.85 18.84 ± 0.99 102.35 ± 4.90

D06 PPC 27.54 ± 1.26 45.87 ± 2.30 333.25 ± 15.24

H07 Clinker 27.45 ± 0.95 30.51 ± 1.44 107.61 ± 4.79

H08 OPC 30.53 ± 1.45 34.14 ± 1.76 120.66 ± 5.90

H09 PPC 26.46 ± 1.11 30.60 ± 1.56 307.57 ± 13.91

Derba PPC 28.57 ± 1.34 41.19 ± 2.03 334.66 ± 14.97

(7)

www.ijsred.com

19]. So the concentrations of natural radioactive materials in clinker can be raised by clay rock since it is a part of igneous rock, which is rich in radioactive materials [18, 19]. In the measured value of activity in clinker samples, all recorded values were seen below the environmental permissible value listed above,

except for sample coded as M01. This may be from the more proportion of clay raw materials used during the processing. In fact, in the heating of the three main raw materials after mixing, coal used as an energy source, and its slag can be easily added to clinker samples. Therefore impurities in coal can also contribute to the concentrations of natural radioactivity in the clinker. Ordinary Portland Cement, (OPC) is a finally processed Portland cement by the factories listed in section 2.1. It is almost the same with clinker with a small amount of some additive raw materials. These additive raw materials, like volcanic ash, can increase the levels of natural radioactivity in OPC. In measured values, these facts were seen for some OPC samples in which the levels of activity concentration is slightly greater that of clinker. The three factories understudy has been using volcanic ash/pumice from the Great Rift Valley in east Africa. This region is full of active volcanos and radioactive materials easily come to the top surfaces of the earth. So taking raw materials for cement factories from such an area will increases the activity concentrations of final products.

Pozzolana Portland cement, (PPC) is lower grade cement produced in the factory under study. Its quality is lowered by adding more additive raw materials to the clinker. This is to increase the quantities of cement and it's adhesive property. The additive raw materials are mainly volcanic ash, gypsum, and slugs of coal. These materials are rich in radioactive materials from their geological and geochemical formations may be gypsum can show low radioactive concentrations due to its more water contents.

Figure 9: 238U, 232T h and 40K concentration in

sampled cement’s additive raw materials.

The natural radioactivity concentration in cement at Pakistan, Brazil, Greece, India, Iran and other countries [20], shows almost similar findings as presented in table 1 and fig 9.

In table 2, the maximum value of Raeq was recorded for the PPC cement sample. The more activity concentration will give more Raeq as seen in eq: 3. This value d i d not cross the world average value given by in UNSCEAR 2000, Annex B, at a distance of 1m from homogeneously distributed 238U, 232T h and 40K, 370Bq/Kg. In the same way, the induced dose rate from these radioactive materials was not above the limit, which was calculated using eq: 4 for almost the same activities of 238U,232T h and 40K.

(8)

www.ijsred.com

Table 2: Activity related radiological hazard

indices in Portland types of cement of one kilogram M for Mugher, D for Dangote and H for Habesha cement factory.

The annual dose rate presented in table 2, were calculated using eq: 5 considering the 20% outdoor

radiation exposure from 238U, 232T h and 40K. The remaining percent, 80% is a time considered for the indoor duration. The samples of study, cement materials are mainly used for the construction of dwellings and exposure can be raised to 80%. Therefore the calculated value of ADR i n table 2 can be increased by four, (4) times. So the maximum value of ADR for sample coded as D06, which is a PPC sample collected from Dangote cement factory, would be 0.27mSv/yr. The maximum annual value, the permissible value is 2.4mSv/yr as explained in section 2.4.3. External and internal hazard indices were not crossi n g the world average limit value, and maximum values were recorded 0.32 and 0.40 for Hex a n d Hin respectively. The internal hazard indices value is more

than that of external due to radon gas from 238U

decay series, which is 222Rn.

In general, the radiological hazard indices recorded in table 2 shows final products and semi-processed types of cement from factories explained in sec: 2.1 are safe to use for construction purposes

according to the limits given on [15]. As seen from PPC, slightly lower grade cement labeled as 32.5N, radiological hazard indices are higher than OPC and Clinker samples. This may be as a result of more additive raw materials like volcanic ash and slugs from coal. These parameters, presented in table 2 are almost the same as done before in different countries [20].

IV.

Conclusion

The activity concentrations and hazard indices measured in this paper are similar to those reported by other investigators [6, 13, 20] from different parts of the world. The main contributors to the overall specific activities in cement, especially PPC examined in this study are attributed to volcanic ash and slags from coal as we did in the previous study and [13]. If these additive raw materials are carefully monitored, the activity concentrations in the final product of cement can be safer for use as building materials. Hazard indices parameters measured in this work were seen below the world permissible value given by [15]. This study can be used as a baseline for the next similar works.

V.

Acknowledgments

The authors are thankful to Mr. Eshetu Tilahun for his collaboration in the laboratory, Ethiopian Radiation Protection Authority, for their laboratory and the chairman of Physics department, Addis Sample

Name

Sample Code

Req

in Kg Bq

DR

in nGy/hr

ADR

in mSv/yr

Hex Hin

M01 Clinker 93.98 ± 4.26 42.05 ± 1.90 0.052 ± 0.0023 0.26 ± 0.012 0.35 ± 0.016

M02 OPC 92.17 ± 4.54 41.48 ± 2.04 0.051 ± 0.0025 0.25 ± 0.012 0.34 ± 0.017

M03 PPC 116.57 ± 5.62 54.00 ± 2.60 0.066 ± 0.0032 0.31 ± 0.015 0.40 ± 0.019

D04 Clinker 58.42 ± 2.61 26.25 ± 1.17 0.032 ± 0.0014 0.16 ± 0.007 0.22 ± 0.009

D05 OPC 55.35 ± 2.64 24.90 ± 1.19 0.031 ± 0.0015 0.15 ± 0.007 0.20 ± 0.009

D06 PPC 118.79 ± 5.72 54.67 ± 2.63 0.067 ± 0.0032 0.32 ± 0.015 0.40 ± 0.019

H07 Clinker 79.36 ± 3.38 35.36 ± 1.51 0.043 ± 0.0012 0.21 ± 0.009 0.29 ± 0.012

H08 OPC 88.64 ± 4.42 39.49 ± 1.97 0.048 ± 0.0024 0.24 ± 0.012 0.32 ± 0.016

H09 OPC 93.90 ± 4.41 43.59 ± 2.04 0.054 ± 0.0025 0.25 ± 0.012 0.33 ± 0.015

Derba PPC 113.24 ± 5.40 52.25 ± 2.48 0.064 ± 0.0030 0.30 ± 0.014 0.38 ± 0.018

(9)

www.ijsred.com

Ababa University for his interest in the present work.

VI.

References

[1] Leonid L. Nkuba and Pendo B. Nyanda, (2017), Natural radioactivity levels and estimation of radiation exposure from soils in Bahi and Manyoni Districts in Tanzania, BRAZILIAN JOURNALL OF RADIATION SCIENCES, 05-03, 01-17.

[2] B. E. zdis, et. al, (2017), Assessment of natural radioactivity in types of cement used as building material in Turkey, J Radioanal Nucl Chem, 311:307316, DOI 10.1007/s10967-016-5074-0. [3] Estokova A., Palascakova L., 2013, Study of

Natural Radioactivity of Slovak Cements, Chemical Engineering transactions, 32,1675-1680.

[4] M. Nain, et. al, (2006), Alpha radioactivity in Indian cement samples, Iran. J. Radiat. Res. 3 (4):171-176.

[5] Faweya Ebenezer Babatope, (2009), Radiation dose estimation from the radioactivity analysis of cement used in Nigeria, Jurnal fizik malaysia, volume 30, number 1 - 4.

[6] D.O. Kpeglo, et. al, (2011), Natural Radioactivity and its Associated Radiological Hazards in

Ghanaian Cement, Research Journal of

Environmental and Earth Sciences 3(2): 160-166. [7] MUKTHA K, EERTHI GOWDA B S, (2016),

Comparative Study on OPC and PPC Composites with Foundry Sand as Partial Replacement for Fine Aggregate An Experimental Approach, Conference Paper, DOI: 10.13140/RG.2.1.1227.9448.

[8] Abd Hadi Kamel, Abdallah Ibrahim Abd El-mageed, Abd El-Bast Abbady, Shaban Harb, Imran

Issa Saleh (2012) Natural Radioactivity of

Environmental Samples and their Impact on the Population at Assalamia-Alhomira Area in Yemen, Scientific & Academic Publishing Yemen, DOI: 10.5923/j.geo.20120205.04

[9]Mohammed Mahmud, et. al., (2014), Measurement of activity concentration levels of radionu- clides in soil samples collected from Bethlehem Province, West Bank, Palestine, Turkish Journal of

Engineering & Environmental Sciences, 38:113-125, doi:10.3906/muh-1303-8.

[10] Pourimani R and Mortazavi Shahroodi M., (2018), Radiological Assessment of the Artificial and Natural Radionuclide Concentrations of Wheat and Barley Samples in Karbala, Iraq. Iran J Med Phys;15:126-131.

[11] CAEN Sys, (2017), Systems and Spectroscopy Solutions, www.caensys.com.

[12] A. Faanu, O. K. Adukpo, et al. (2016) Natural radioactivity levels in soils, rocks and water at a mining concession of Perseus gold mine and surrounding towns in Central Region of Ghana, a springer journal, DOI 10.1186/s40064-016-1716-5.

[13] T. Hosseini, et. al, (2006), Assessment of radionuclides in imported foodstuffs in Iran, Iran. J.Radiat. Res. pp. 149-153.

[14] Hosseini,A.A. Fathivand, H. Barati, M. Karimi, (2006), Assessment of radionuclides in im- ported foodstuffs in Iran, Iran. J. Radiat. Res. pp. 149-153.

[15] UNSCER (2000, Vol. I) SOURCES AND EFFECTS OF IONIZING RADIATION, United Na- tions Scientific Committee on the Effects of Atomic Radiation UNSCEAR 2000 Report to the General Assembly, Annex B.

[16] Ayham Assie, et. al., (2016) Determination of natural radioactivity by gamma spectroscopy in Balad soil, Iraq, Pelagia Research Library Advances in Applied Science Research, 7(1):35-41.

[17] A. El-Taher and S. Makhluf, (2011), Radiological significance of Egyptian limestone and al- abaster used for construction of dwellings, Indian Journal of Pure & Applied Physics, Vol. 49, pp. 157-161.

[18] http://weppi.gtk.fi/publ/foregsatlas/text/Th.pdf

[19] Stanley S. Johnson, (1991), Natural adiation, Virginia division of mineral resources, Volume 37, No. 2, pp. 1-8.

Figure

Figure 1: Brands of collected cements
Figure 3: Prepared samples for gamma
Figure 4: HPGe-detector and its shielding
Figure 7: Efficiency curve measured by the certified standard sources in the region of interest
+3

References

Related documents

The C terminus (about 40 amino acid residues) appears to be rather conserved and hydrophobic among all class I and II polyester synthases, suggesting that this region

The tool used consists of two parts; the first part consists of socio- demographic data (gender, residence, monthly income, occupation, education level, age group

may be clinically useful in the treatment of asthma, CP- 105,696 was evaluated in vitro, using chemotaxis and flow cytometry assays, and in vivo, using a primate

As part of its aim to promote all aspects of entomology, the Entomological Society of Southern Africa (ESSA) initiated the Young Entomologists’ Travel

Importantly, under race tube assay conditions with the levels of luc gene expression and luciferin used here, it is clear that the amount of light produced is less than the amount

This research finds significant parameters for Thai small and medium enterprises (SMEs) such as commitment to the product or service, enthusiasm for competition, passion

AAV, anti-neutrophil cytoplasmic antibody-associated vasculitis; ALPS, autoimmune lymphoproliferative syndrome; ANCA, anti-neutrophil cytoplasmic antibody; BEH, Behçet ’ s disease;

For record values from power function distribution, one is referred to Ahsanullah (2004), where distributional properties of upper record values from a three