Environmental Radiation Dosimetry for school buildings, hospitals and health centers in Babil Governorate-Iraq using TL-technique

: The current research aims to evaluate the dose rate of gamma rays emitted from school buildings, hospitals and health centers in several locations in Babil Governorate using the TL method. To achieve the objectives of the research, measurements were taken at 49 school building sites and 29 hospital and health center sites using the thermal luminescence technique. The results of this study indicate that the inhabited areas within the environmental monitoring stations are places where the radiation is normal and the average dose rate in school buildings, hospitals and health centers to which humans are exposed is within the permissible limit.


Introduction
The thermoluminescence dosimeter is a useful method for determining ionizing radiation dosage.When the TL material is subjected to radiation, it absorbs the energy and stores it until it is heated.The TL glow curve shows the intensity of emitted light as a function of temperature.Most TL dosimeters respond linearly to dosages up to a few Grays (Azorín Nieto, 2004;Furetta, 2010).Physically, TL dosimeters are tiny.They are suitable for several medical applications (Akkurt, Gunoglu, & Arda, 2014;Al-Salihi, Salim, Alfahed, & Badran, 2020;Azorín Nieto, 2004).Environmental background radiation must be precisely assessed to identify exposures related to the emission of radioactivity from the nuclear site; the amount of environmental radiation must be evaluated to appropriately quantify population exposure.Many researchers have studied this subject to better understand the environmental radiation contamination in soil, water, air, salt, and food to safeguard the environment from the hazards of radiation exposure to people (Abualhail, Abbas, & Alsalihi, 2017;Alfahed, Imran, Majeed, & Badran, 2020;Alsalihi & Abualhiall, 2019;Bdran, Abul-Hail, & Obeed, 2020;Hail & Talib, 2020;Mollah, Husain, & Rahman, 1986;Rejah, Oraibi, & Al-Salihi, 2020;Salman, Al-Ahmad, Badran, & Emshary, 2015).The current study was conducted out in several areas of Babil Governorate, employing TL-dosimetry to conduct a radiation survey of 10 locations.Governorate Center, Al Emam, Al Mashrooa, Al-Qasim, Al Talee'a, Al Hashimiyah, Al Kifl, Al Nile, Al Showmali, Al Midhatiya, are the locations chosen.
In this paper it has included calculated the dos rate of emitted gamma-ray from school buildings, hospitals and health centers taken from different locations in Babil Governorate by using TL-technique.

Materials and Methods
The thermoluminescence dosimeter is more favorable than other approaches for detecting low radiation doses.This is because thermoluminescence dosimeters are tiny and inexpensive, need little field effort, are measured in a laboratory setting, and have acceptable sensitivity, accuracy, and reliability under harsh environmental conditions.Because of their higher degree of accuracy sensitivity, (TLD-200) chips were used for this work (Al-Salihi, Abul-Hail, Badran, & Alfahed, 2022;Alfahed et al., 2020;Alhiall & Alsalihi, 2019;Hassan, Abul-Hail, Badran, & Al-Salihi, 2022).A factory-produced metering container containing 20 dosimeters per batch was used for the calibration and determination of the TL response per m rad (Kellerer, Hahn, & Rossi, 1992).A full batch of dosimeters was annealed for 1 h at 400 degrees Celsius, followed by 2 h at 100 0 C (Al-Salihi et al., 2021;Alfahed et al., 2019;Bdran et al., 2020;Bujdosó, 1987;Ramadhan, Al-Salihi, & Khalaf, 2020).This treatment also improves the dosimeter's sensitivity.The three annealed TLD chips are contained in an opaque plastic container in each environmental dosimeter.For three months, the TLD is permanently stationed at various places under monitoring.The period of this research was from August 2022 to October 2022).There are 78 TLD monitoring stations spread out across100 kilometers, covering all of the province's major districts.A TLD reader (HARSHAW FIL TROL 2000-B/C) with a steady nitrogen flow rate (100 to 500 mL/min) was used to read out all TLD chips.To decrease fading, the chips were post-annealed for 10 min at 100°C just before reading.Chips were preand post-annealed according to established techniques (Harley, 1972).TLD from the same batch was irradiated at the thermoluminescence laboratory at the Department of Physics, College of Education for Pure Science, University of Basrah, using a 137 Cs gamma ray source manufactured by company J.L. Shepherd and Associates in California.Where the dose supplied by this source was approximately equal to (20 mrad/min) in 1985 AD and it decreased to approximately (8.362 mrad/min) in 2022 AD where t1/2 = 30.07y.The 78 sampling stations are located in ten zones.All zones comprise two to five stations in school buildings, hospitals and health centers.

Results and Discussions
The average environmental gamma-ray radiation rate for school buildings, hospitals and health centers AL-Diwaniyah Governorate was studied and measured using thermoluminescence technology.For this objective, 78 environmental stations were set up and implemented.Three months of monitoring were carried out.Table 1 and 2 summarize the result of average dose rates measured using TLD-200 chips for three months in the Babil Governorate (school buildings, hospitals and health).Table1 shows that the mean average environmental gamma-ray dose is from 4.54 µrad/h to 8.06 µrad/h with an average dose rate is 6.334µad/h in the school building.The minimum value obtained for sample code A4 (Al Emam) and the maximum for sample code B1 (Al Nile).The high value was recorded as, 8.06 µ rad/h.From figure 1 it can be seen that monthly values do not show any definite pattern, although a slight random variation in the period time three month was observed in school buildings stations, Also as can be seen in Table 2, the mean average environmental gamma-ray dose is quoted at 4.77 µrad/h up to 7.98 µrad/h with an average dose rate of 6.119µad/h in hospital, and health centers.The minimum value was obtained for sample code G2 (Governorate Center) and a maximum for sample code Sh2 (AL-Shafeih).The high value was recorded as, 7.98 µ rad/h.From figure 2, it can be seen that monthly values do not show any definite pattern, although a slight random variation in the period time three months was observed.This variation in measured dose values for different stations in Babil Governorate (school buildings, hospitals, and health) may be due to different in the building material used and the presence of laboratory equipment and presence of medical devices and radiology equipment and medicines and medical supplies at different sites as well as variability inherent in the placement of the dosimeter, and the preparation and calibration of the dosimeters (Burke, 1975).The results proved that the inhabited fields lying within the environmental monitoring states are the areas in which the radiation is natural and the rate that the human being exposed equals (1-20) mSv/y which is considered a natural exposure limit (OBEED & BADRAN, 2020;Protection, 2007).The contribution of radiation doses to the effect on the thermoluminescence signal from the regions listed in the tables 1 and 2, are shown in Figure 3 and Figure 4, respectively.It appears that some areas have high absorbed radiation doses, which have a direct effect on the thermal thermoluminescence signal.These results are in line with those of previous researchers, and they can be attributed to building materials' inherently radioactive constituents (Al-Salihi et al., 2022;Alhiall & Alsalihi, 2019;El-Taher, 2012;Hassan et al., 2022;Imani et al., 2021;Lewicka, Piotrowska, Łukaszek-Chmielewska, & Drzymała, 2022).

Figure 2 :
Figure 2: The dose rate of emitted gamma rays from different stations from hospitals and health centers.

Figure 3 :
Figure 3: A plot of a dose rate as a function of TLsignal for regions illustrated in table 1 .

Figure 4 :
Figure 4: A plot of a dose rate as a function of TL signal for regions illustrated in table 2.