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Studies of ionizing radiation shielding properties of silica-based commercial glasses used in Bangladeshi dwellings Sabina Yasmin, Bijoy SonkerBarua, Mayeen Uddin Khandaker, Michael Adekunle Olatunji, Masud Kamal, Faruque Uz Zaman Chowdhury, Md. Abdur Rashid
Presented by Sabina Yasmin Ph.D Student Chittagong University of Engineering & Technology Bangladesh
World Challenge Development of energy sector without releasing significant quantities of CO2 associated with fossil-fuel-fired power plants.
South Korea, France, USA, Japan, etc. are producing energy via nuclear power plants.
Nuclear power plants
Nuclear power plant in Bangladesh
Bangladesh has also taken an effort to build nuclear power station to boost up her rapid growing industrial economy.
Leakage of radiation
Probability of leakage of radiation and hazardous wastes cannot be neglected
Radiation Protection
The protection from radiation depends on-
[US Department of Defense 2005].
Radiation protection in houses
Radiation protection inside the houses should be given most priority as most people spend about 80% of their time inside houses and offices
Shielding materials
Shielding materials are to be selected based on their mechanical strength, easiness of production/ cost effectiveness and resistance to radiation damage. In general Lead, Steel, Concrete etc. are typically used to protect.
Glass is now a widely used material in modern building constructions due to its - - heat resistive capacity, - stiffness, - lesser weight, - transparent to visible light - but opaque to ultraviolet & infrared light.
Glass material
Following the rapid growing economy, the Bangladeshi dwellers are replacing their traditional (mud, bamboo, and wood-based) houses to modern multistoried buildings, where different types of glasses are being used as decorative as well as structural materials.
House of Bangladesh
Glass made building in Bangladesh
The assessment of the suitability of various kinds of glasses for shielding of ionizing radiation shows highly significant since the glasses used in Bangladesh have not been analyzed for this purpose.
Glass for shielding of ionizing radiation
A number of works in literature (building materials) showed: A material, which has high value of absorption coefficient, possesses high value of shielding effectiveness and vice versa.
Introduction (Cont’d)
However, the knowledge of basic radiological parameters (attenuation coefficient and effective atomic number) of glass used in building construction is important for the assessment of possible radiation exposure to the population and also to make a protective shielding design for both the artificial and natural radiation.
Introduction (Cont’d)
μ = τ (photoelectric) + σ (Compton) + κ (pair)
The photoelectric effect dominates at small values of gamma ray energy. Compton scattering dominates at intermediate energies, and The electron-positron pair production dominates at high energies.
Aim of this Work
In this study, the radiological parameters such as - linear attenuation coefficient, - mass attenuation coefficient, - half-value layer and - radiation protection efficiency of commercial glasses used in Bangladeshi dwellings were measured to assess residential safety.
Furthermore, the investigated glass samples were also assessed to know the probability for using as a thermoluminesence dosimeter (TLD) for environmental radiation monitoring purposes.
Thermoluminesence dosimeter (TLD)
List of samples
Name of Glass
Thickness Slice Area Manufactured
Rider
0.5 cm
10 cm2
China
Nasir Bangladesh
Usmania Bangladesh
PHP Bangladesh
Materials and Methods
p-type coaxial HPGe detector - ORTEC; GEM-25P: - 57.5 mm crystal diameter; - 51.5 mm thickness; - +2800V bias voltage. Detector energy resolution: - 1.678 keV at 1.3 MeV of 60Co line - 28.2% relative efficiency. A computer program: - Gamma Vision 5.0 software (EG&G Ortec).
Detector’s configuration
HPGe detector
The transmitted gamma-ray intensity is measured with or without placing the investigated glass samples in between the source and the detector.
Arrangement of sample placing
Before measurement, the detector was calibrated for energy and efficiency using a customize multinuclides gamma-ray standard source comprising of 109Cd, 57Co, 60Co, 137Cs and 88Y with initial activity of 5.046 µCi. Efficiency calibration was carried out for 86,400 s
y = 78.179x-1.043 R² = 0.9992
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Phot
o-pe
ak e
ffici
ency
(%)
Gamma-ray energy (keV)
Energy and efficiency calibration
During the measurement, the multinuclides gamma-ray standard source was placed on the upper surface of the studied glass samples (0.5 cm thickness), and the distance between the sample and detector surface was kept at 8.5 cm.
Sample placement
The values of µ, µ/ρ, HVL and RP for each sample were then calculated using those following equations.
µ = (1/t) ln (Io/I )……………………...(1) µ/ρ = (1/ρt) ln (Io/I)………………..…(2) HVL = ln2 / µ ………………………..(3) RP = (1- I/Io) x 100………………….(4)
The FWHM associated with the gamma-ray energies at 59 keV (241Am), 661 keV (137Cs), 1173 keV & 1332 keV ( 60Co) were selected for determining the incident (Io) and transmitted (I) photon intensities.
Effective atomic number is needed for identifying proper dosimetric properties of an absorber.
The fractional weight of each element of a glass sample were determined by using the EDX techniques.
Energy Dispersive X-ray Spectroscopy machine
Figure shows the electron image and spectrum for fractional weight of an investigated glass sample by EDX procedures.
Zeff = (a1Z1m + a2Z2
m+…………+ anZnm) 1/m…………(1)
a = Ne/Net …………………………………..…….….…(2) Ne = NA Z (Wi)/Aw……………….……………..….……(3)
The values of fractional weight of each element of a mixture the effective atomic number, the fractional contribution of electron number and electron number per gram for each sample were then calculated using those following equations.
Brand Name Element (Wi %)
Usmania
C 20.71 O 36.04 Na 0.79 Mg 0.83 Al 0.44 Si 1.92 Ca 39.13
Rider
C 14.1 O 41.85 Na 2.37 Mg 0.98 Al 0.27 Si 10.42 Ca 30.08
Brand Name Element (Wi %)
PHP
C 15.3 O 43.84 Na 2.64 Mg 1.31 Al 0.28 Si 10.07 Ca 26.51
Nasir
C 17.96 O 39.22 Na 4.6 Mg 1.44 Al 0.62 Si 13.7 Ca 22.23 K 0.47
0.000
0.200
0.400
0.600
0.800
1.000
59 keV 661 keV 1173 keV 1332 keV
0.97
0.46 0.39 0.38
0.90
0.42 0.36 0.33
0.84
0.39 0.35 0.32
0.71
0.35 0.31 0.28 Lin
ear
atte
neat
ion
coef
ficie
nt
Gamma energy
RiderPHPNasirOsmania
Results and discussion
µ59keV ˃ µ661, 1173,1332 keV
µ : Rider > PHP > Nasir > Usmania
Zeff : Usmania > Rider > PHP > Nasir
Compton scattering is weak dependence on Zeff and photoelectric effect is strong depends on Zeff this is this reason to get the similar values of µ at the higher energies (661 keV, 1173 keV, 1332 keV).
µ59keV ˃ µ661, 1173,1332 keV
Usmania brand did not follow the proportionality between the linear attenuation coefficient and effective atomic number. Reasons: a) Weight fraction - Usmania: (Si- 1.92%) and other brands: (Si- 10% to 14%). b) Density - Rider (2.03 g/cm3), PHP (2.3 g/cm3), Nasir (1.4 g/cm3), Usmania (1.8 g/cm3).
µ : Rider > PHP > Nasir > Usmania Zeff : Usmania > Rider > PHP > Nasir
0.000
0.100
0.200
0.300
0.400
0.500
0.600
0.700
59 keV 661 keV 1173 keV 1332 keV
0.48
0.23 0.19 0.19
0.39
0.18 0.16 0.14
0.61
0.28 0.26 0.24
0.39
0.19 0.17 0.16
Mas
s att
enua
tion
coef
ficie
nt
(cm
2 /g)
Gamma energy
RiderPHPNasirOsmania
µ : Rider > PHP > Nasir > Usmania
µ/ρ : Nasir > Rider > Usmania > PHP
This order of mass attenuation coefficient is followed by the physical density of the respective glass samples.
Therefore, it may be assumed that for nearer effective atomic numbers (in this study these were 13.6 to 15.0), the mass attenuation coefficients mostly depends on the density of the materials.
µ : Rider > PHP > Nasir > Usmania
µ/ρ : Nasir > Rider > Usmania > PHP
Density (g/cm3) : Usmania (1.8 ) > Rider (2.03) > PHP (2.3) > and Nasir (1.4)
0.000
1.000
2.000
3.000
59 keV 661 keV 1173 keV 1332 keV
0.71
1.50 1.79 1.83
0.77
1.64 1.94 2.09
0.83
1.77 1.96 2.14
0.98
1.99 2.26
2.46
Hal
f-va
lue
laye
r (c
m)
Gamma energy
RiderPHPNasirOsmania
HVL: Usmania > Nasir > PHP > Rider
µ : Rider > PHP > Nasir > Usmania
HVL increase with increasing photon energy
0.000
1.000
2.000
3.000
4.000
5.000
6.000
7.000
Rider PHP Nasir Osmania Steel Lead Concrete
1.81 2.02 2.05 2.36 2.16
1.25
6.05
HV
L du
e to
60C
o
HVL of the studied glass samples are comparable with Steel and Lead, and approximately one third that of Concrete.
HVL due to 60Co - Glass (1.79-2.46 cm), Concrete (6.05 cm), Steel (2.16 cm), Lead (1.25 cm), Tungsten (0.79 cm).
0.000
5.000
10.000
15.000
20.000
25.000
30.000
35.000
40.000
59 keV 661 keV 1173 keV 1332 keV
38.47
20.57 17.58 17.22
36.08
19.00 16.39 15.25
34.26
17.74 16.18 14.97
29.85
15.99 14.20 13.13
Rad
iatio
n pr
otec
tion
effic
ienc
y of
bu
ildin
g m
ater
ials
Gamma energy
RiderPHPNasirOsmania
RPE : Rider > PHP > Nasir > Usmania
µ : Rider > PHP > Nasir > Usmania
Higher linear attenuation of coefficient’s of material shows higher radiation protection efficiency.
RPE : Rider > PHP > Nasir > Usmania
µ : Rider > PHP > Nasir > Usmania
12.00
13.00
14.00
15.00
16.00
Osmania Rider PHP Nasir
15.05 14.34
13.90 13.55
Eff
ectiv
e at
omic
nu
mbe
r (Z
eff)
Brand name
Zeff : Usmania > Rider > PHP > Nasir
Zeff (13.548 - 15.048) ≠ TLD-100 with Zeff of 8.2 ≈ TLD-200 with Zeff of 16.3
Higher effective mass number of material can reduce the gamma rays more effectively due to the higher number of electrons per atom
Brand Name
Element (Wi %)
Usmania C 20.71 Si 1.92 Ca 39.13
Rider C 14.1 Si 10.42 Ca 30.08
PHP C 15.3 Si 10.07 Ca 26.51
Nasir C 17.96 Si 13.7 Ca 22.23
Zeff : Usmania > Rider > PHP > Nasir This order followed by the weight fractional contribution and density of each branded glass samples studied.
Conclusion The dosimetric and protective capability from ionizing
radiation of commercial glasses used in Bangladeshi dwellings have been investigated
The linear attenuation coefficients found in the
investigated four brands at 59 keV were almost double that of attenuations for 661 keV, 1173 keV and 1332 keV photon energies.
Photoelectric absorption at 59 keV and Compton
scattering at energies 661 keV, 1173 keV and 1332 keV were the predominant interaction mechanisms for gamma rays and took part in decreasing the attenuation of the studied materials with increasing photon energies.
According to the values of linear attenuation coefficients found in this study, the investigated brands of glasses can be arranged as Rider > PHP > Nasir > Usmania. Along with the effective atomic number, the contributing weight fraction of the constituents’ elements and density of the glass samples had a role for varying the order of attenuation coefficient of the four branded glass samples. The shielding property, half value layer in the investigated glass samples are found comparable with Steel and Lead.
Among the studied brands, Rider (China) shows relatively better indices to be used as ionizing radiation shielding material. In this investigation the measured range of effective atomic number (13.548 to 15.048) makes the glass samples strong candidates with the TLD-200 (Zeff =16.3). The study finally showed that the glass samples collected here will be more suitable for environmental dose measurements, and for shielding, these are comparable with steel and lead materials.
References
1) Ref: Half Value Layer- NDE/NDT Resource Center. Available at <https://www.ndeed.org/Education Resources/Community
College/Radiography/Physics/Half Value Layer.htm>
Acknowledgments The authors are grateful to the staffs of the Applied Radiation Laboratory of University of Malaya, Malaysia for their kind cooperation during sample measurements. Authors thank to the organizing committee of 6th Asia-Pacific Symposium on Radiochemistry, •ICC Jeju• Jeju Island, Korea.
Thank you
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