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Radiation shielding and effective atomic number studies in different types of shielding concretes, lead base and non-lead base glass systems for total electron interaction: A comparative study
Nuclear Engineering and Design 280 (2014) 440–448
Contents lists available at ScienceDirect
Nuclear Engineering and Design journal homepage: www.elsevier.com/locate/nucengdes
Radiation shielding and effective atomic number studies in different types of shielding concretes, lead base and non-lead base glass systems for total electron interaction: A comparative study Murat Kurudirek ∗ Faculty o f Science, Department of Physics, Ataturk University, 25240 Erzurum, Turkey
h i g h l i g h t s • Radiation shielding calculations for concretes and glass systems. • Assigning effective atomic number for the given materials for total electron interaction. • Glass systems generally have better shielding ability than concretes.
a r t i c l e
i n f o
Article history: Received 16 July 2014 Received in revised form 5 September 2014 Accepted 15 September 2014
a b s t r a c t Concrete has been widely used as a radiation shielding material due to its extremely low cost. On the other hand, glass systems, which make everything inside visible to observers, are considered as promising shielding materials as well. In the present work, the effective atomic numbers, Zeff of some concretes and glass systems (industrial waste containing glass, Pb base glass and non-Pb base glass) have been calculated for total electron interaction in the energy region of 10 keV–1 GeV. Also, the continuous slowing down approximation (CSDA) ranges for the given materials have been calculated in the wide energy region to show the shielding effectiveness of the given materials. The glass systems are not only compared to different types of concretes but also compared to the lead base glass systems in terms of shielding. Moreover, the obtained results for total electron interaction have been compared to the results for total photon interaction wherever possible. In general, it has been observed that the glass systems have superior properties than most of the concretes over the high-energy region with respect to the electron interaction. Also, glass systems without lead show better electron stopping than lead base glasses at some energy regions as well. Along with the photon attenuation capability, it is seen that Fly Ash base glass systems have not only greater electron stopping capability but also have greater photon attenuation especially in high energy region when compared with standard shielding concretes. © 2014 Elsevier B.V. All rights reserved.
1. Introduction Ionizing radiations such as energetic photons and charged particles such as electrons take place in nuclear technology applications such as reactors, nuclear power plants, nuclear medicine . . . etc. However, wherever the energetic photons or electrons take place in an application, there is always a safety issue coming down due to their health hazard potential. Therefore, proper shield design is of vital importance not only for protection of personnel working in
∗ Tel.: +90 442 2314167; fax: +90 442 2314109. E-mail address: [email protected] http://dx.doi.org/10.1016/j.nucengdes.2014.09.020 0029-5493/© 2014 Elsevier B.V. All rights reserved.
places where radiation takes place but also protection of laboratory equipment from radiation hazard. Concretes containing different aggregates have widely been used as shielding materials not only for photons but also for fast neutrons. It is widely available and is a low cost material when compared to other shielding materials. On the other hand, glass systems have some promising properties in terms of not only radiation shielding capability but also being visible to light, which makes it possible to observe and control the experimental conditions. Also, with the help of vitrification process glass plays an important role in reducing the hazards of different types of wastes by keeping them chemically stable for a long time. Calculating CSDA range is considered to be a very close approximation to the average path length traveled by a charged particle as
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Effective atomic number (Zeff)
it slows down to rest. In the continuous slowing down approximation, the rate of energy loss at every point along the track is assumed to be equal to the total stopping power (Berger et al., 1993). The Zeff on the other hand, is used in radiation response characterization of multi-element materials consisting of elements with different Z. Zeff is similar to the atomic number, Z of the elements and gives information on how radiation interact with the absorbing medium. Up to now, most efforts have been paid to investigate the radiation shielding properties of concretes and glass systems for photons and fast neutrons. The photons’ shielding parameters and effective atomic numbers have been studied in shielding glasses (Manohara et al., 2009; Kurudirek et al., 2010a; Singh et al., 2008; Kirdsiri et al., 2009; Kaewkhao et al., 2010; Singh et al., 2002), concretes (Rahimi et al., 2009; Bashter, 1997; El-Khayatt and Akkurt, 2013; Un and Demir, 2013; Demir and Keles¸, 2006) and some other shielding materials (Bas¸tu˘g et al., 2011; Yılmaz et al., 2011). To the best of the author’s knowledge, there is almost no study available to investigate Zeff of concretes and glass systems for electron interaction and CSDA ranges for different concretes and glasses. At this point, an effort has been made to study Zeff and radiation shielding properties in different concretes and glass systems with respect to the total electron interaction in the wide energy region 10 keV–1 GeV.
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Energy (MeV) Fig. 1. Effective atomic numbers of the concretes for total electron interaction from 10 keV to 1 GeV.
2. Materials and method
3. Results and discussion 3.1. Effective atomic number (Zeff ) The variation of Zeff with electron energy for concretes and glass samples has been shown in the Figs. 1–4. Significant variations have been observed in Zeff due to the dominance of different electron interaction processes. Generally, the value of Zeff increases as energy increases for the given materials. The variation of Zeff is less in concretes when compared to glass systems. Especially, in concretes that have relatively low-Z constituents, i.e. ordinary concrete have more or less the same Zeff in the entire energy region.
However, the concretes that have high-Z constituents, i.e. steel magnetite have not only higher Zeff values but also have greater variation in Zeff . The main partial electron interaction processes are collisional and radiative processes and they give different weight to the total electron interaction in different energy regions. As the energy increases, the radiative process starts dominating the total electron interaction and leads an increase in Zeff values. Also, the radiative process has higher Z-dependence than collisional process. This state clearly explains the higher Zeff values in the highenergy region especially for materials having high Z elements as constituents. Table 1 presents simple descriptive statistics for Zeff values of given materials in the energy region 10 keV–1 GeV. 3.2. CSDA range comparison between the concretes and glasses Calculating CSDA range is one of the convenient ways to estimate roughly the electron stopping in different materials since -2
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In the present work, the selected materials consist of seven types of concretes (Bashter, 1997) (Ordinary, Hematite-Serpentine, Ilmenite-Limonite, Basalt-Magnetite, Ilmenite, Steel-Scrap, SteelMagnetite), lead base glasses (PbO–B2 O3 ) (Kirdsiri et al., 2009) and non-lead base glasses; flyash (industrial waste) base glasses (BaO-flyash-B2 O3 ) (Singh et al., 2008) and bismuth base glasses (Bi2 O3 –B2 O3 ) (Singh et al., 2002). In order to calculate Zeff , mass stopping powers of the used materials for electrons have been calculated first using the ESTAR database (Berger et al., 1993). Then using the mass stopping power data for elements, stopping cross-sections (cm−1 , expressed per atom) of elements were obtained for Z = 1–35 to construct a matrix. Thereafter, the stopping cross-sections of materials have been interpolated between adjacent stopping cross-section data to obtain Zeff . The CSDA ranges of the materials have been calculated using ESTAR database (Berger et al., 1993). The total mass stopping power is the sum of two stopping powers namely collision stopping power and radiative stopping power corresponded to different electron interaction processes. It has been reported that the uncertainties of the calculated collision stopping powers for electrons are estimated to be 1% to 2% above 100 keV, 2% to 3% (in low-Z materials) and 5% to 10% (in high-Z materials) between 100 keV and 10 keV (International Commission on Radiation Units Measurements, 1984). The uncertainties of the radiative stopping powers are estimated to be 2% above 50 MeV, 2–5% between 50 MeV and 2 MeV, and 5% below 2 MeV (Berger et al., 1993).
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Energy (MeV) Fig. 2. Effective atomic numbers of the barium borate flyash glasses (G1–G5) for total electron interaction from 10 keV to 1 GeV.
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Fig. 3. Effective atomic numbers of the lead borate glasses (L1–L5) for total electron interaction from 10 keV to 1 GeV.
Fig. 4. Effective atomic numbers of the bismuth borate glasses (B1–B5) for total electron interaction from 10 keV to 1 GeV.
CSDA gives an approximate average path length traveled by the charged particle before it slows down to rest. At this point, the concretes and glass systems were compared in terms of CSDA in the continuous energy region (Figs. 5–7). Shown are the relative differences (%) in CSDA ranges between concretes and glass systems in Figs. 5–7. The positive values of the differences (%) indicate that concretes have higher values of CSDA range than glass systems. Thus, for better shielding the CSDA values should be as small as possible. The negative differences (%) clearly indicate the superiority of glass systems over the concretes in terms of shielding. It can be seen that the G1 glass sample has lower values of CSDA range than steel magnetite, steel scrap and ilmenite concretes from 10 keV to 10 MeV and it has lower values
than ilmenite-limonite concrete from 10 keV to 1 MeV (Fig. 5). After 30 MeV, the G1 glass sample shows better shielding than ordinary, basalt-magnetite and hematite-serpentine concretes. G2 glass has lower CSDA ranges than steel-magnetite, steel-scrap, ilmenite and ilmenite-limonite concretes for energy regions 10 keV–10 MeV, 10 keV–7 MeV, 10 keV–70 keV, >100 MeV, respectively. After 30 MeV, ordinary, basalt-magnetite, hematiteserpentine and ilmenite concretes have higher values of CSDA than G2 sample. For G3 sample, it has been found that the steel-magnetite, steel-scrap and ilmenite-limonite concretes have higher values of CSDA range in the energy regions 10 keV–10 MeV, 10 keV–1 MeV and >40 MeV, respectively. G3 sample has found to have lower CSDA ranges than ordinary, hematite-serpentine, basalt-magnetite and ilmenite concretes from 20 MeV to 1 GeV. G4
Table 1 Basic statistical values of Zeff for concretes and glass systems for total electron interaction in the energy region 10 keV–1 GeV. Concretes and glass systems
N
Mean
Ordinary Hematite-serpentine Basalt-magnetite Ilmenite-limonite Ilmenite Steel-scrap Steel-magnetite G1(BaO–flyash–B2 O3 )1 G2(BaO–flyash–B2 O3 )2 G3(BaO–flyash–B2 O3 )3 G4(BaO–flyash–B2 O3 )4 G5(BaO–flyash–B2 O3 )5 L1(PbO–B2 O3 )a L2(PbO–B2 O3 )b L3(PbO–B2 O3 )c L4(PbO–B2 O3 )d L5(PbO–B2 O3 )e B1(Bi2 O3 –B2 O3 )aa B2(Bi2 O3 –B2 O3 )ab B3(Bi2 O3 –B2 O3 )ac B4(Bi2 O3 –B2 O3 )ad B5(Bi2 O3 –B2 O3 )ae
81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81
8.38 9.25 10.10 11.97 12.13 13.64 15.68 10.02 10.58 10.96 11.59 12.02 9.67 11.20 13.01 15.26 18.30 9.55 10.24 11.02 11.85 13.74
a,b,c,d,e
refer to the, (x)PbO − (100 − x)B2 O3 where x = 30, 40, 50, 60, 70, respectively. refer to the, (x)Bi2 O3 − (100 − x)B2 O3 where x = 30, 35, 40, 45, 55, respectively. refer to the, (x)BaO − (0.6 − x)Flyash-(0.4)B2 O3 where x = 0.24, 0.30, 0.34, 0.40, 0.44, respectively.
aa,ab,ac,ad,ae 1,2,3,4,5
Zeff Min
Median
Max
7.83 8.22 9.25 10.79 11.02 12.04 14.03 8.87 9.15 9.36 9.70 9.93 7.60 8.27 9.28 10.62 12.29 7.57 7.85 8.22 8.65 9.78
8.24 8.72 9.61 11.20 11.39 12.98 15.12 9.23 9.56 9.79 10.19 10.65 8.30 9.49 11.43 13.67 16.34 8.15 8.68 9.32 9.95 12.15
9.50 11.27 11.82 13.78 13.90 15.76 17.99 12.33 13.20 13.80 14.73 15.39 13.27 15.65 18.30 21.55 25.65 13.12 14.23 15.38 16.62 19.43
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Fig. 5. (a–e) Differences (%) in CSDA ranges between G1–G5 glasses and different types of concretes in the energy region of 10 keV–1 GeV.
sample has found to have lower CSDA ranges thus superior shielding properties than steel-magnetite and steel-scrap concretes up to 10 MeV and 40 keV, respectively. Except for the steel-magnetite concrete, G4 have lower CSDA ranges than all the concretes from 20 MeV to 1 GeV. When it comes to the glass type G5, it should be
noted that it has lower values of CSDA ranges than steel-magnetite from 10 keV to 1 MeV. In the energy range of 20 MeV to 1 GeV, G5 have smaller CSDA ranges than all the concretes. B1 type glasses have smaller CSDA ranges than steel-magnetite and steel-scrap in the energy regions 10 keV–10 MeV and
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Fig. 6. (a–e) Differences (%) in CSDA ranges between B1–B5 glasses and different types of concretes in the energy region of 10 keV–1 GeV.
10 keV–1 GeV, respectively (Fig. 6). B2 and B3 glasses have lower values of CSDA ranges than steel-magnetite concrete in the entire energy region. After 20 MeV, all types of concretes have higher CSDA ranges than all B type glasses. L1 glass systems have superior shielding properties than steel-magnetite concrete before 20 MeV whereas it has superior
shielding properties than all the concretes after 20 MeV except for steel-magnetite (Fig. 7). It has to be noted that L1 glasses have lower CSDA ranges than steel-scrap in the entire energy region. L2, L3, L4 glasses have lower CSDA ranges than all types of concretes after 20 MeV whereas L5 glass has lower values of CSDA ranges than all concretes from 15 MeV to 1 GeV.
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Fig. 7. (a–e) Differences (%) in CSDA ranges between L1–L5 glasses and different types of concretes in the energy region of 10 keV–1 GeV.
3.3. CSDA range comparison between the lead base and non-lead base glasses The glass systems were also compared in themselves with respect to lead base and non-lead base. It is well known that
although lead is a good shield for photons as well as particle radiation it is not an environmentally friendly material. At this point, materials having shielding properties as effective as lead but at the same time having low environmental issues are have to be considered. G1, G2 and G3 glasses have superior properties than lead
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Fig. 8. (a–e) Differences (%) in CSDA ranges between G1–G5 glasses and L1–L5 glasses in the energy region of 10 keV–1 GeV.
based glasses (L1–L5) from 10 keV to 10 MeV (Fig. 8). Up to 10 MeV, G4 and G5 glasses have lower values of CSDA ranges than all the concretes except for the L1 glass, the G4 and G5 glasses seem to be as effective as L1 sample in terms of radiation shielding after 10 MeV
and 20 MeV, respectively. B1, B2, and B3 glasses have lower CSDA ranges than all the L glasses except for the L1 glass from 10 keV to 10 MeV (Fig. 9). It should be noted that B1 glass has more or less the same CSDA ranges with L1 in the entire energy region. All B glasses
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Fig. 9. (a–e) Differences (%) in CSDA ranges between B1–B5 glasses and L1–L5 glasses in the energy region of 10 keV–1 GeV.
except for B1 have lower CSDA ranges than L1 after 10 MeV. B4 has better shielding properties than L3, L4 and L5 glasses before 10 MeV and has lower CSDA ranges than L1 and L2 after 10 MeV. B5 has better shielding properties than L4 and L5 glasses before 10 MeV and has lower CSDA ranges than L1, L2 and L3 after 10 MeV.
3.4. Comparison of flyash based glass (G1–G5) with concretes for electron and photon shielding In a previous study, concretes and glass systems with and without lead have been studied with respect to the photon shielding
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Table 2 The energy regions that Fly Ash glasses (G1–G5) have better shielding properties than concretes for both photons and electrons. Concretes
G1
G2
G3
G4
G5
Ordinary Hem. serp. Bas. magn. Ilm. lim. Ilm. Ste-Scr.
30 MeV–1 GeV 30 MeV–1 GeV 30 MeV–1 GeV 30 keV–1 MeV 30 keV–200 keV 50 keV–200 keV
30 MeV–1 GeV 30 MeV–1 GeV 30 MeV–1 GeV 100 MeV–1 GeV 30 MeV–1 GeV 50 keV–200 keV
20 MeV–1 GeV 20 MeV–1 GeV 20 MeV–1 GeV 40 MeV–1 GeV 20 MeV–1 GeV 50 keV–200 keV
20 MeV–1 GeV 20 MeV–1 GeV 20 MeV–1 GeV 20 MeV–1 GeV 20 MeV–1 GeV 20 MeV–1 GeV
20 MeV–1 GeV 20 MeV–1 GeV 20 MeV–1 GeV 20 MeV–1 GeV 20 MeV–1 GeV 20 MeV–1 GeV
properties in the energy range of 1 keV–100 GeV (Kurudirek et al., 2010b). When it comes to photons, mean free path (mfp) is a similar parameter to CSDA range as it represents average distance between the two successive interactions of photons. In the present work, G type glass samples (G1–G5), which contain industrial waste (Fly Ash) as a constituent, have been compared with concretes considering photons and electrons together. Given are the energy regions that G type glasses show superior shielding properties than concretes for both electrons and photons in Table 2. It has been seen that most of the Fly Ash glass samples show better shielding properties than most of the shielding concretes in high-energy region. 4. Conclusions In the present work, the Zeff for total electron interaction has been calculated for some shielding concretes and glass systems in the energy region 10 keV–1 GeV for the first time. In general, the Zeff of the given materials has been found to increase as energy increases. The variation in Zeff seems to be less in materials which have relatively low Z constituents whereas the variation in Zeff becomes much more in materials having high Z elements as constituents. The lower the CSDA values of the materials, the better the shielding properties of the materials. When compared with some standard shielding concretes, it can be concluded that after 20 MeV most of the B type (Bi2 O3 –B2 O3 ) and L type (PbO–B2 O3 ) glass samples have lower values of CSDA ranges than most of the concretes and most of the G type (BaO-flyash-B2 O3 ) glasses have lower values of CSDA ranges than concretes except for steel-magnetite and steelscrap. When compared with lead base glasses (L1–L5), most of the G type glasses have superior shielding properties than lead base glasses in the energy region 10 keV–10 MeV. Also before 10 MeV, B1, B2 and B3 type glasses have better or nearly equal shielding properties than lead base glasses and B4 and B5 glasses have better shielding properties than lead base glasses except for L1, L2 glasses. It is interesting to note that B1, B2 and B3 glasses have lower CSDA ranges than L1 glasses and B4 has lower CSDA ranges than L1, L2
glasses and B5 has lower CSDA ranges than L1, L2 and L3 glasses. Finally, the G type glass samples have been compared with concretes in terms of both photon and electron shielding. It has been observed that especially for high-energy region the Fly Ash base glasses have superior shielding properties not only for electrons but also for photons. References Bashter, I.I., 1997. Ann. Nucl. Energy 24, 1389–1401. Bas¸tu˘g, A., I˙ c¸elli, O., Gürol, A., S¸ahin, Y., 2011. Ann. Nucl. Energy 38, 2283–2290. Berger, M.J., Coursey, J.S., Zucker, M.A., Chang, J., 2005. ESTAR, PSTAR, and ASTAR: Computer Programs for Calculating Stopping-Power and Range Tables for Electrons, Protons, and Helium Ions (version 1.2.3). National Institute of Standards and Technology, Gaithersburg, MD, Available: http://physics.nist.gov/Star (Originally published as: Berger, M.J., NISTIR 4999, National Institute of Standards and Technology, Gaithersburg, MD (1993)). Demir, D., Keles¸, G., 2006. Nucl. Instrum. Methods B 2, 501–504. El-Khayatt, A.M., Akkurt, I., 2013. Ann. Nucl. Energy 60, 8–14. International Commission on Radiation Units Measurements, 1984. Stopping Powers for Electrons and Positrons. ICRU Report 37. Kaewkhao, J., Pokaipisit, A., Limsuwan, P., 2010. J. Nucl. Mater. 399, 38–40. Kirdsiri, K., Kaewkhao, J., Pokaipisit, A., Chewpraditkul, W., Limsuwan, P., 2009. Ann. Nucl. Energy 36, 1360–1365. Kurudirek, M., Aygun, M., Erzeneo˘glu, S.Z., 2010a. Appl. Radiat. Isot. 68, 1006–1011. Kurudirek, M., Özdemir, Y., S¸ims¸ek, Ö., Durak, R., 2010b. J. Nucl. Mater. 407, 110–115. Manohara, S.R., Hanagodimath, S.M., Gerward, L., 2009. J. Nucl. Mater. 393, 465–472. Rahimi, R.A., Raisali, G., Sadrnezhaad, S.K., Alipour, A., 2009. J. Nucl. Mater. 385, 527–532. Singh, K., Singh, H., Sharma, V., Nathuram, R., Khanna, A., Kumar, R., Bhatti, S.S., Sahota, H.S., 2002. Nucl. Instrum. Methods B 194, 1–6. Singh, S., Kumar, A., Singh, D., Thind, S.K., Mudahar, S.G., 2008. Nucl. Instrum. Methods B 266, 140–146. Un, A., Demir, F., 2013. Appl. Radiat. Isot. 80, 73–77. Yılmaz, E., Baltas, H., Kırıs, E., Ustabas, I˙ ., Cevik, U., El-Khayatt, A.M., 2011. Ann. Nucl. Energy 38, 2204–2209. Dr. Kurudirek began working in Ataturk University, Faculty of Science and Department of Physics as Assist. Prof. Dr. in 2011 after finishing his Ph.D. in the same department. His research interests cover fundamental interaction of ionizing radiation with different types of materials. He has expertise on X-ray fundamental processes and photon-interaction cross-section data, the effective atomic number and related parameters in dosimetry and radiation protection and the photon buildup factor.
Contents lists available at ScienceDirect
Nuclear Engineering and Design journal homepage: www.elsevier.com/locate/nucengdes
Radiation shielding and effective atomic number studies in different types of shielding concretes, lead base and non-lead base glass systems for total electron interaction: A comparative study Murat Kurudirek ∗ Faculty o f Science, Department of Physics, Ataturk University, 25240 Erzurum, Turkey
h i g h l i g h t s • Radiation shielding calculations for concretes and glass systems. • Assigning effective atomic number for the given materials for total electron interaction. • Glass systems generally have better shielding ability than concretes.
a r t i c l e
i n f o
Article history: Received 16 July 2014 Received in revised form 5 September 2014 Accepted 15 September 2014
a b s t r a c t Concrete has been widely used as a radiation shielding material due to its extremely low cost. On the other hand, glass systems, which make everything inside visible to observers, are considered as promising shielding materials as well. In the present work, the effective atomic numbers, Zeff of some concretes and glass systems (industrial waste containing glass, Pb base glass and non-Pb base glass) have been calculated for total electron interaction in the energy region of 10 keV–1 GeV. Also, the continuous slowing down approximation (CSDA) ranges for the given materials have been calculated in the wide energy region to show the shielding effectiveness of the given materials. The glass systems are not only compared to different types of concretes but also compared to the lead base glass systems in terms of shielding. Moreover, the obtained results for total electron interaction have been compared to the results for total photon interaction wherever possible. In general, it has been observed that the glass systems have superior properties than most of the concretes over the high-energy region with respect to the electron interaction. Also, glass systems without lead show better electron stopping than lead base glasses at some energy regions as well. Along with the photon attenuation capability, it is seen that Fly Ash base glass systems have not only greater electron stopping capability but also have greater photon attenuation especially in high energy region when compared with standard shielding concretes. © 2014 Elsevier B.V. All rights reserved.
1. Introduction Ionizing radiations such as energetic photons and charged particles such as electrons take place in nuclear technology applications such as reactors, nuclear power plants, nuclear medicine . . . etc. However, wherever the energetic photons or electrons take place in an application, there is always a safety issue coming down due to their health hazard potential. Therefore, proper shield design is of vital importance not only for protection of personnel working in
∗ Tel.: +90 442 2314167; fax: +90 442 2314109. E-mail address: [email protected] http://dx.doi.org/10.1016/j.nucengdes.2014.09.020 0029-5493/© 2014 Elsevier B.V. All rights reserved.
places where radiation takes place but also protection of laboratory equipment from radiation hazard. Concretes containing different aggregates have widely been used as shielding materials not only for photons but also for fast neutrons. It is widely available and is a low cost material when compared to other shielding materials. On the other hand, glass systems have some promising properties in terms of not only radiation shielding capability but also being visible to light, which makes it possible to observe and control the experimental conditions. Also, with the help of vitrification process glass plays an important role in reducing the hazards of different types of wastes by keeping them chemically stable for a long time. Calculating CSDA range is considered to be a very close approximation to the average path length traveled by a charged particle as
M. Kurudirek / Nuclear Engineering and Design 280 (2014) 440–448 -2
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-1
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0
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1
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2
10
3
10
Ordinary Hematit-Serpentine Ilmenite-Limonit Basalt-Magnetite Ilmenite Steel-Scrap Steel-Magnetite
21 20 19
Effective atomic number (Zeff)
it slows down to rest. In the continuous slowing down approximation, the rate of energy loss at every point along the track is assumed to be equal to the total stopping power (Berger et al., 1993). The Zeff on the other hand, is used in radiation response characterization of multi-element materials consisting of elements with different Z. Zeff is similar to the atomic number, Z of the elements and gives information on how radiation interact with the absorbing medium. Up to now, most efforts have been paid to investigate the radiation shielding properties of concretes and glass systems for photons and fast neutrons. The photons’ shielding parameters and effective atomic numbers have been studied in shielding glasses (Manohara et al., 2009; Kurudirek et al., 2010a; Singh et al., 2008; Kirdsiri et al., 2009; Kaewkhao et al., 2010; Singh et al., 2002), concretes (Rahimi et al., 2009; Bashter, 1997; El-Khayatt and Akkurt, 2013; Un and Demir, 2013; Demir and Keles¸, 2006) and some other shielding materials (Bas¸tu˘g et al., 2011; Yılmaz et al., 2011). To the best of the author’s knowledge, there is almost no study available to investigate Zeff of concretes and glass systems for electron interaction and CSDA ranges for different concretes and glasses. At this point, an effort has been made to study Zeff and radiation shielding properties in different concretes and glass systems with respect to the total electron interaction in the wide energy region 10 keV–1 GeV.
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Energy (MeV) Fig. 1. Effective atomic numbers of the concretes for total electron interaction from 10 keV to 1 GeV.
2. Materials and method
3. Results and discussion 3.1. Effective atomic number (Zeff ) The variation of Zeff with electron energy for concretes and glass samples has been shown in the Figs. 1–4. Significant variations have been observed in Zeff due to the dominance of different electron interaction processes. Generally, the value of Zeff increases as energy increases for the given materials. The variation of Zeff is less in concretes when compared to glass systems. Especially, in concretes that have relatively low-Z constituents, i.e. ordinary concrete have more or less the same Zeff in the entire energy region.
However, the concretes that have high-Z constituents, i.e. steel magnetite have not only higher Zeff values but also have greater variation in Zeff . The main partial electron interaction processes are collisional and radiative processes and they give different weight to the total electron interaction in different energy regions. As the energy increases, the radiative process starts dominating the total electron interaction and leads an increase in Zeff values. Also, the radiative process has higher Z-dependence than collisional process. This state clearly explains the higher Zeff values in the highenergy region especially for materials having high Z elements as constituents. Table 1 presents simple descriptive statistics for Zeff values of given materials in the energy region 10 keV–1 GeV. 3.2. CSDA range comparison between the concretes and glasses Calculating CSDA range is one of the convenient ways to estimate roughly the electron stopping in different materials since -2
10
-1
10
0
10
1
10
2
10
3
10
G1 G2 G3 G4 G5
15
Effective atomic number (Zeff)
In the present work, the selected materials consist of seven types of concretes (Bashter, 1997) (Ordinary, Hematite-Serpentine, Ilmenite-Limonite, Basalt-Magnetite, Ilmenite, Steel-Scrap, SteelMagnetite), lead base glasses (PbO–B2 O3 ) (Kirdsiri et al., 2009) and non-lead base glasses; flyash (industrial waste) base glasses (BaO-flyash-B2 O3 ) (Singh et al., 2008) and bismuth base glasses (Bi2 O3 –B2 O3 ) (Singh et al., 2002). In order to calculate Zeff , mass stopping powers of the used materials for electrons have been calculated first using the ESTAR database (Berger et al., 1993). Then using the mass stopping power data for elements, stopping cross-sections (cm−1 , expressed per atom) of elements were obtained for Z = 1–35 to construct a matrix. Thereafter, the stopping cross-sections of materials have been interpolated between adjacent stopping cross-section data to obtain Zeff . The CSDA ranges of the materials have been calculated using ESTAR database (Berger et al., 1993). The total mass stopping power is the sum of two stopping powers namely collision stopping power and radiative stopping power corresponded to different electron interaction processes. It has been reported that the uncertainties of the calculated collision stopping powers for electrons are estimated to be 1% to 2% above 100 keV, 2% to 3% (in low-Z materials) and 5% to 10% (in high-Z materials) between 100 keV and 10 keV (International Commission on Radiation Units Measurements, 1984). The uncertainties of the radiative stopping powers are estimated to be 2% above 50 MeV, 2–5% between 50 MeV and 2 MeV, and 5% below 2 MeV (Berger et al., 1993).
14
15
14
13
13
12
12
11
11
10
10
9
9 -2
10
-1
10
0
10
1
10
2
10
3
10
Energy (MeV) Fig. 2. Effective atomic numbers of the barium borate flyash glasses (G1–G5) for total electron interaction from 10 keV to 1 GeV.
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26
0
10
1
2
10
10
3
22
20
18
18
16
16
14
14
12
12
10
10
8
8 -2
19
24 22
-1
10
0
10
1
2
10
10
3
10
-1
10 20
26
20
10
-2
10
L1 L2 L3 L4 L5
24
Effective atomic number (Zeff)
10
18
Effective atomic number (Zeff)
-2
10
17 16
10
0
10
1
10
2
10
3
10
20 19
B1 B2 B3 B4 B5
18 17 16
15
15
14
14
13
13
12
12
11
11
10
10
9
9
8
8
7 -2 10
-1
10
Energy (MeV)
0
10
1
10
2
10
7
3
10
Energy (MeV)
Fig. 3. Effective atomic numbers of the lead borate glasses (L1–L5) for total electron interaction from 10 keV to 1 GeV.
Fig. 4. Effective atomic numbers of the bismuth borate glasses (B1–B5) for total electron interaction from 10 keV to 1 GeV.
CSDA gives an approximate average path length traveled by the charged particle before it slows down to rest. At this point, the concretes and glass systems were compared in terms of CSDA in the continuous energy region (Figs. 5–7). Shown are the relative differences (%) in CSDA ranges between concretes and glass systems in Figs. 5–7. The positive values of the differences (%) indicate that concretes have higher values of CSDA range than glass systems. Thus, for better shielding the CSDA values should be as small as possible. The negative differences (%) clearly indicate the superiority of glass systems over the concretes in terms of shielding. It can be seen that the G1 glass sample has lower values of CSDA range than steel magnetite, steel scrap and ilmenite concretes from 10 keV to 10 MeV and it has lower values
than ilmenite-limonite concrete from 10 keV to 1 MeV (Fig. 5). After 30 MeV, the G1 glass sample shows better shielding than ordinary, basalt-magnetite and hematite-serpentine concretes. G2 glass has lower CSDA ranges than steel-magnetite, steel-scrap, ilmenite and ilmenite-limonite concretes for energy regions 10 keV–10 MeV, 10 keV–7 MeV, 10 keV–70 keV, >100 MeV, respectively. After 30 MeV, ordinary, basalt-magnetite, hematiteserpentine and ilmenite concretes have higher values of CSDA than G2 sample. For G3 sample, it has been found that the steel-magnetite, steel-scrap and ilmenite-limonite concretes have higher values of CSDA range in the energy regions 10 keV–10 MeV, 10 keV–1 MeV and >40 MeV, respectively. G3 sample has found to have lower CSDA ranges than ordinary, hematite-serpentine, basalt-magnetite and ilmenite concretes from 20 MeV to 1 GeV. G4
Table 1 Basic statistical values of Zeff for concretes and glass systems for total electron interaction in the energy region 10 keV–1 GeV. Concretes and glass systems
N
Mean
Ordinary Hematite-serpentine Basalt-magnetite Ilmenite-limonite Ilmenite Steel-scrap Steel-magnetite G1(BaO–flyash–B2 O3 )1 G2(BaO–flyash–B2 O3 )2 G3(BaO–flyash–B2 O3 )3 G4(BaO–flyash–B2 O3 )4 G5(BaO–flyash–B2 O3 )5 L1(PbO–B2 O3 )a L2(PbO–B2 O3 )b L3(PbO–B2 O3 )c L4(PbO–B2 O3 )d L5(PbO–B2 O3 )e B1(Bi2 O3 –B2 O3 )aa B2(Bi2 O3 –B2 O3 )ab B3(Bi2 O3 –B2 O3 )ac B4(Bi2 O3 –B2 O3 )ad B5(Bi2 O3 –B2 O3 )ae
81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81 81
8.38 9.25 10.10 11.97 12.13 13.64 15.68 10.02 10.58 10.96 11.59 12.02 9.67 11.20 13.01 15.26 18.30 9.55 10.24 11.02 11.85 13.74
a,b,c,d,e
refer to the, (x)PbO − (100 − x)B2 O3 where x = 30, 40, 50, 60, 70, respectively. refer to the, (x)Bi2 O3 − (100 − x)B2 O3 where x = 30, 35, 40, 45, 55, respectively. refer to the, (x)BaO − (0.6 − x)Flyash-(0.4)B2 O3 where x = 0.24, 0.30, 0.34, 0.40, 0.44, respectively.
aa,ab,ac,ad,ae 1,2,3,4,5
Zeff Min
Median
Max
7.83 8.22 9.25 10.79 11.02 12.04 14.03 8.87 9.15 9.36 9.70 9.93 7.60 8.27 9.28 10.62 12.29 7.57 7.85 8.22 8.65 9.78
8.24 8.72 9.61 11.20 11.39 12.98 15.12 9.23 9.56 9.79 10.19 10.65 8.30 9.49 11.43 13.67 16.34 8.15 8.68 9.32 9.95 12.15
9.50 11.27 11.82 13.78 13.90 15.76 17.99 12.33 13.20 13.80 14.73 15.39 13.27 15.65 18.30 21.55 25.65 13.12 14.23 15.38 16.62 19.43
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Fig. 5. (a–e) Differences (%) in CSDA ranges between G1–G5 glasses and different types of concretes in the energy region of 10 keV–1 GeV.
sample has found to have lower CSDA ranges thus superior shielding properties than steel-magnetite and steel-scrap concretes up to 10 MeV and 40 keV, respectively. Except for the steel-magnetite concrete, G4 have lower CSDA ranges than all the concretes from 20 MeV to 1 GeV. When it comes to the glass type G5, it should be
noted that it has lower values of CSDA ranges than steel-magnetite from 10 keV to 1 MeV. In the energy range of 20 MeV to 1 GeV, G5 have smaller CSDA ranges than all the concretes. B1 type glasses have smaller CSDA ranges than steel-magnetite and steel-scrap in the energy regions 10 keV–10 MeV and
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Fig. 6. (a–e) Differences (%) in CSDA ranges between B1–B5 glasses and different types of concretes in the energy region of 10 keV–1 GeV.
10 keV–1 GeV, respectively (Fig. 6). B2 and B3 glasses have lower values of CSDA ranges than steel-magnetite concrete in the entire energy region. After 20 MeV, all types of concretes have higher CSDA ranges than all B type glasses. L1 glass systems have superior shielding properties than steel-magnetite concrete before 20 MeV whereas it has superior
shielding properties than all the concretes after 20 MeV except for steel-magnetite (Fig. 7). It has to be noted that L1 glasses have lower CSDA ranges than steel-scrap in the entire energy region. L2, L3, L4 glasses have lower CSDA ranges than all types of concretes after 20 MeV whereas L5 glass has lower values of CSDA ranges than all concretes from 15 MeV to 1 GeV.
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Fig. 7. (a–e) Differences (%) in CSDA ranges between L1–L5 glasses and different types of concretes in the energy region of 10 keV–1 GeV.
3.3. CSDA range comparison between the lead base and non-lead base glasses The glass systems were also compared in themselves with respect to lead base and non-lead base. It is well known that
although lead is a good shield for photons as well as particle radiation it is not an environmentally friendly material. At this point, materials having shielding properties as effective as lead but at the same time having low environmental issues are have to be considered. G1, G2 and G3 glasses have superior properties than lead
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Fig. 8. (a–e) Differences (%) in CSDA ranges between G1–G5 glasses and L1–L5 glasses in the energy region of 10 keV–1 GeV.
based glasses (L1–L5) from 10 keV to 10 MeV (Fig. 8). Up to 10 MeV, G4 and G5 glasses have lower values of CSDA ranges than all the concretes except for the L1 glass, the G4 and G5 glasses seem to be as effective as L1 sample in terms of radiation shielding after 10 MeV
and 20 MeV, respectively. B1, B2, and B3 glasses have lower CSDA ranges than all the L glasses except for the L1 glass from 10 keV to 10 MeV (Fig. 9). It should be noted that B1 glass has more or less the same CSDA ranges with L1 in the entire energy region. All B glasses
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Fig. 9. (a–e) Differences (%) in CSDA ranges between B1–B5 glasses and L1–L5 glasses in the energy region of 10 keV–1 GeV.
except for B1 have lower CSDA ranges than L1 after 10 MeV. B4 has better shielding properties than L3, L4 and L5 glasses before 10 MeV and has lower CSDA ranges than L1 and L2 after 10 MeV. B5 has better shielding properties than L4 and L5 glasses before 10 MeV and has lower CSDA ranges than L1, L2 and L3 after 10 MeV.
3.4. Comparison of flyash based glass (G1–G5) with concretes for electron and photon shielding In a previous study, concretes and glass systems with and without lead have been studied with respect to the photon shielding
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Table 2 The energy regions that Fly Ash glasses (G1–G5) have better shielding properties than concretes for both photons and electrons. Concretes
G1
G2
G3
G4
G5
Ordinary Hem. serp. Bas. magn. Ilm. lim. Ilm. Ste-Scr.
30 MeV–1 GeV 30 MeV–1 GeV 30 MeV–1 GeV 30 keV–1 MeV 30 keV–200 keV 50 keV–200 keV
30 MeV–1 GeV 30 MeV–1 GeV 30 MeV–1 GeV 100 MeV–1 GeV 30 MeV–1 GeV 50 keV–200 keV
20 MeV–1 GeV 20 MeV–1 GeV 20 MeV–1 GeV 40 MeV–1 GeV 20 MeV–1 GeV 50 keV–200 keV
20 MeV–1 GeV 20 MeV–1 GeV 20 MeV–1 GeV 20 MeV–1 GeV 20 MeV–1 GeV 20 MeV–1 GeV
20 MeV–1 GeV 20 MeV–1 GeV 20 MeV–1 GeV 20 MeV–1 GeV 20 MeV–1 GeV 20 MeV–1 GeV
properties in the energy range of 1 keV–100 GeV (Kurudirek et al., 2010b). When it comes to photons, mean free path (mfp) is a similar parameter to CSDA range as it represents average distance between the two successive interactions of photons. In the present work, G type glass samples (G1–G5), which contain industrial waste (Fly Ash) as a constituent, have been compared with concretes considering photons and electrons together. Given are the energy regions that G type glasses show superior shielding properties than concretes for both electrons and photons in Table 2. It has been seen that most of the Fly Ash glass samples show better shielding properties than most of the shielding concretes in high-energy region. 4. Conclusions In the present work, the Zeff for total electron interaction has been calculated for some shielding concretes and glass systems in the energy region 10 keV–1 GeV for the first time. In general, the Zeff of the given materials has been found to increase as energy increases. The variation in Zeff seems to be less in materials which have relatively low Z constituents whereas the variation in Zeff becomes much more in materials having high Z elements as constituents. The lower the CSDA values of the materials, the better the shielding properties of the materials. When compared with some standard shielding concretes, it can be concluded that after 20 MeV most of the B type (Bi2 O3 –B2 O3 ) and L type (PbO–B2 O3 ) glass samples have lower values of CSDA ranges than most of the concretes and most of the G type (BaO-flyash-B2 O3 ) glasses have lower values of CSDA ranges than concretes except for steel-magnetite and steelscrap. When compared with lead base glasses (L1–L5), most of the G type glasses have superior shielding properties than lead base glasses in the energy region 10 keV–10 MeV. Also before 10 MeV, B1, B2 and B3 type glasses have better or nearly equal shielding properties than lead base glasses and B4 and B5 glasses have better shielding properties than lead base glasses except for L1, L2 glasses. It is interesting to note that B1, B2 and B3 glasses have lower CSDA ranges than L1 glasses and B4 has lower CSDA ranges than L1, L2
glasses and B5 has lower CSDA ranges than L1, L2 and L3 glasses. Finally, the G type glass samples have been compared with concretes in terms of both photon and electron shielding. It has been observed that especially for high-energy region the Fly Ash base glasses have superior shielding properties not only for electrons but also for photons. References Bashter, I.I., 1997. Ann. Nucl. Energy 24, 1389–1401. Bas¸tu˘g, A., I˙ c¸elli, O., Gürol, A., S¸ahin, Y., 2011. Ann. Nucl. Energy 38, 2283–2290. Berger, M.J., Coursey, J.S., Zucker, M.A., Chang, J., 2005. ESTAR, PSTAR, and ASTAR: Computer Programs for Calculating Stopping-Power and Range Tables for Electrons, Protons, and Helium Ions (version 1.2.3). National Institute of Standards and Technology, Gaithersburg, MD, Available: http://physics.nist.gov/Star (Originally published as: Berger, M.J., NISTIR 4999, National Institute of Standards and Technology, Gaithersburg, MD (1993)). Demir, D., Keles¸, G., 2006. Nucl. Instrum. Methods B 2, 501–504. El-Khayatt, A.M., Akkurt, I., 2013. Ann. Nucl. Energy 60, 8–14. International Commission on Radiation Units Measurements, 1984. Stopping Powers for Electrons and Positrons. ICRU Report 37. Kaewkhao, J., Pokaipisit, A., Limsuwan, P., 2010. J. Nucl. Mater. 399, 38–40. Kirdsiri, K., Kaewkhao, J., Pokaipisit, A., Chewpraditkul, W., Limsuwan, P., 2009. Ann. Nucl. Energy 36, 1360–1365. Kurudirek, M., Aygun, M., Erzeneo˘glu, S.Z., 2010a. Appl. Radiat. Isot. 68, 1006–1011. Kurudirek, M., Özdemir, Y., S¸ims¸ek, Ö., Durak, R., 2010b. J. Nucl. Mater. 407, 110–115. Manohara, S.R., Hanagodimath, S.M., Gerward, L., 2009. J. Nucl. Mater. 393, 465–472. Rahimi, R.A., Raisali, G., Sadrnezhaad, S.K., Alipour, A., 2009. J. Nucl. Mater. 385, 527–532. Singh, K., Singh, H., Sharma, V., Nathuram, R., Khanna, A., Kumar, R., Bhatti, S.S., Sahota, H.S., 2002. Nucl. Instrum. Methods B 194, 1–6. Singh, S., Kumar, A., Singh, D., Thind, S.K., Mudahar, S.G., 2008. Nucl. Instrum. Methods B 266, 140–146. Un, A., Demir, F., 2013. Appl. Radiat. Isot. 80, 73–77. Yılmaz, E., Baltas, H., Kırıs, E., Ustabas, I˙ ., Cevik, U., El-Khayatt, A.M., 2011. Ann. Nucl. Energy 38, 2204–2209. Dr. Kurudirek began working in Ataturk University, Faculty of Science and Department of Physics as Assist. Prof. Dr. in 2011 after finishing his Ph.D. in the same department. His research interests cover fundamental interaction of ionizing radiation with different types of materials. He has expertise on X-ray fundamental processes and photon-interaction cross-section data, the effective atomic number and related parameters in dosimetry and radiation protection and the photon buildup factor.