Radiological impacts of the usability of clay and kaolin as raw material in manufacturing of structural building materials in Turkey

NATURAL RADIOACTIVITY AND ASSESSMENT OF HAZARD INDICES OF THE SOIL FOUND AT SUNG VALLEY, MEGHALAYA

In this work, the variation of the radioactivity at different depth of the soil found at the Sung Valley in West Jaiñtia Hills District of Meghalaya in India is estimated by using the gamma-ray spectroscopy. The average activity concentration of 226Ra, 232Th and 40K for soil samples at different depths are measured to be 57, 156 and 352 Bq kg-1, respectively. The radiological hazard indices for the soil samples are calculated using standard models in order to determine the safe utility of these materials that are being used to manufacture domestic products by the locals. Values of all the radiological hazard indices are observed to be within the internationally recommended values as proposed by the European Commission and the United Nations Scientific Committee on the Effects of Atomic Radiation. The present study ensures that the soil analysed presents a negligible radiation hazard, and produced poetries and artefacts radiological incidence will stay within the allowed natural limit.

Evaluation of natural radioactivity levels and potential radiological hazards of common building materials utilized in Mediterranean region, Turkey

Radiometric measurement of building materials is very important to assess the internal and external exposure caused by the ionizing radiation emitted from terrestrial radionuclides in building materials. The activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K in fifty-eight samples of fifteen different structural and covering building materials commonly used in Osmaniye province located in the Mediterranean region of Turkey were measured by using gamma-ray spectroscopy. The activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K varied from 2.5 ± 0.1 (marble) to 145.7 ± 4.4 (clay brick), 1.3 ± 0.1 (marble) to 154.3 ± 4.1 (marble), and 8.6 ± 0.2 (sand) to 1044.1 ± 70.3 (granite), respectively. Radiological parameters (activity concentration index, alpha index, indoor absorbed gamma dose rate and the corresponding annual effective dose rate, and excess lifetime cancer risk) were estimated to evaluate the health hazards associated with these building materials. Since the estimated values of these parameters are within the recommended safety limits or criteria values, the use of the studied building materials in the construction of dwellings can be considered to be safe for the residents of the region.

Radiometric analysis of micas used in many industries and evaluation of radiological hazards

Mica group minerals have been utilized in various industries such as paint, cement, rubber, plastic, paper, automotive, cosmetics, textile, etc. due to their unique electrical, thermal, and mechanical properties. In this study, the radiometric properties of 58 mica samples collected from three quarries operated commercially in Turkey were investigated using gamma-ray spectroscopy with an HPGe detector. The average activity concentrations of 226Ra, 232Th, and 40K analyzed in mica samples were found as 12, 44, and 2763 Bq kg−1, respectively. The radon emanation coefficient and radon mass exhalation rate of mica samples varied from 4 to 22% with an average of 10% and 0.4–5.9 µBq kg−1 s−1 with an average of 2.6 µBq kg−1 s−1, respectively. The radiological hazard caused by the utilization of mica samples as raw materials in the cement and concrete industry was evaluated for adults by calculating the gamma index and annual effective dose due to external exposure indoor. The study results revealed that there are no significant radiological hazards associated with the utilization of mica samples as building raw materials.

Dating the historical old city walls of Songkhla Thailand using thermoluminescence technique

The Old Historical Wall, located in Bo Yang, Songkhla Province, Thailand, is an archaeological icon believed to have been constructed during the reign of Rama III, as indicated in the royal archives, around 1837–1840 CE. However, the recorded age is the result of unofficial documentation. The establishment was based on speculation from circumstantial evidence and local stories. The wall is made of bricks that underwent a heating process before being used for the construction. We therefore propose the use of the thermoluminescence technique for dating the wall. The samples include brick rubble from three excavation sites next to the wall. To determine the age, we estimate the radiation dose rate and the accumulated dose for each sample. The dose rate of the sample is determined using gamma spectroscopy with a high-purity germanium detector. For the accumulated dose, we employ the additive dose method using Co-60 with a dose range of 0–100 Gy. Glow curves are then deconvoluted using the general-order kinetics model. The results yield three superposition glow peaks at three different temperature ranges. Plateau tests are also carried out to find a proper temperature for dating purposes. Comparing the plateau test and the result of deconvolution, we find that the glow curve temperature suitable for dating was within 200–310 °C. The accumulated doses are then evaluated using the area under the curve of the peak temperature. The date is then determined as the ratio between the accumulated dose and the dose rate. The results indicate that the age is approximately 174–192 years, so that the wall was built around 1827–1841 CE, with one standard deviation interval. The duration is in agreement with the recorded age of the wall inscribed in the country's historical archives.

Radioactivity levels and transfer factor for granite mining field in Asa, North-central Nigeria

Natural radioactivity measurement and dose assessment are important aspects of radiation protection. The goal of this study is to validate the previous results obtained from the in-situ measurements in the study area in order to ascertain the level of radiation hazards to the populaces living around the mining site.A3 × 3-inch lead-shielded NaI(Tl) detector was used to measure the activity concentrations of 40 K, 238 U and 232 Thin soil, water and guinea corn grain samples collected from a granite mining field in Asa, Kwara State, North-central Nigeria. The overall mean activity concentrations of 40 K, 238 U and 232 Th are 441.06, 11.51 and 15.42 Bqkg-1for the soil samples, 20.67, 0.66, and 0.88 BqL-1 for the water samples and 214.31, 5.25 and 8.86 Bqkg-,1respectively for the grain samples. The bioaccumulation/transfer factors are 0.49, 0.46 and 0.58 for 40 K, 238 U and 232 Th respectively. The mean values of all the radiological hazard parameters are within the permissible limit recommended by the United Nations Scientific Committee on the Effects of Atomic Radiation. Consequently, the risk of indoor and outdoor gamma radiation exposure is comparatively less for these Granite soils. Hence, the results in this study will reference future studies in terms of basic radiological data.

Radiological evaluation of the use of clay brick and pumice brick as a structural building material

In this study, clay brick (CBRICK) and pumice brick (PBRICK) samples used as structural material in the construction of dwellings, schools, workplaces and factories in Turkey were compared with each other from a radiological viewpoint. The activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K naturally occurring in CBRICK and PBRICK samples collected from different regions of Turkey were determined by using a gamma-ray spectrometer with a high purity germanium detector (HPGe). The average activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in CBRICK and PBRICK samples were found as 35.4 ± 3.3, 37.5 ± 2.4 and 593.7 ± 42.7 Bq kg^-1 and 81.9 ± 2.5, 65.8 ± 6.0 and 1066.0 ± 46.6 Bq kg^-1, respectively. The radon surface exhalation rate (EX_S) and radon mass exhalation rate (EX_M) of CBRICK and PBRICK samples were measured by using an active radon gas analyzer with an accumulation container. The average value of EX_S and EX_M of CBRICK and PBRICK samples found as 45.9 ± 2.9 mBq m^-2 h^-1 and 3.7 ± 2.9 mBq kg^-1 h^-1 and 100.9 ± 4.7 mBq m^-2 h^-1 and 9.9 ± 0.5 mBq kg^-1 h^-1, respectively. Radiological parameters related to external and internal exposure to members of the public such as the radiation protection index, alpha index, and indoor absorbed gamma radiation dose rate and the corresponding annual effective dose from external exposure, annual effective dose from inhalation of radon, and the lifetime cancer risk were estimated for CBRICK and PBRICK samples. The results were compared with each other and with the international recommended limits or criteria. The results reveal that the average values measured and estimated for CBRICK samples are approximately two times lower than those measured and estimated for PBRICK samples. Thus, from the radiological viewpoint, clay brick is preferable to pumice brick as a structural material in the building sector.

Radioactivity and radiological hazards from a kaolin mining field in Ifonyintedo, Nigeria

The concentrations of the radionuclides in the subsurface formation (soils and rocks) solely depend on their geological origin, which enables its variation from point to point on the Crust. Construction materials can possess elevated concentrations of radioactivity if their byproducts are mined from contaminated radionuclide sources. In this article, results of in situ measurements of radioactivity concentrations of ⁴⁰K, ²³²Th, and ²³⁸U as well as gamma doses and radiological hazards from kaolin mining field were presented and evaluated. Eleven stations were randomly occupied in order to cover the upper axis of a kaolin mining field in Ifonyintedo. The radiometric survey was achieved using Super-Spec (RS-125), equipment capable of measuring activity concentrations and gamma doses. For each location, measurements were taken four times, while its mean and standard deviation values were estimated for better accuracy. The overall mean activity concentrations (for ⁴⁰K, ²³²Th and ²³⁸U) and gamma dose were estimated as 93.9 Bq kg^-1, 65.1 Bq kg^-1, 38.2 Bq kg^-1, and 59.6 nGyh^-1 respectively. The estimated radiological hazards from the measured parameters showed that the overall mean concentrations of Radium Equivalent, External and Internal Hazards, Annual Effective Dose, Gamma and Alpha Indices, and Representative Level index are 138.5 Bq kg^-1, 0.37 0.48, 0.29 mSvyr^-1, 0.48, 0.19, and 0.97 respectively. By comparing the mean values of the activity concentrations and their radiological risks with the several world standards from the literature, kaolin deposits in Ifonyintedo are highly rich in thorium.

Data on the radiometric survey over a kaolinitic terrain in Dahomey Basin, Nigeria

This article consists the in situ data sets of activity concentrations of radionuclides (K-40, Th-232 and U-238) and gamma radiation dose rates measured about 1 m above a kaolinitic terrain in Ifonyintedo, Dahomey Basin, SW Nigeria. Nineteen (19) data points were randomly occupied at the lower axis of the kaolin field using a hand-held detector known as Super-Spec (RS 125). At each data point, the measurements were taken four times, while their averages and standard deviations were estimated in order to ensure accuracy. The radiometric survey was carried out between December, 2017 and January, 2018. The data sets were processed and analyzed via a descriptive statistics. The data can be explored further by estimating the radiological risks to the miners on the field, and to correlate the activity concentrations of the data with the activity concentrations of the tiles that are produced from the kaolin deposits in Ifonyintedo. Furthermore, the data from this article could be compared with other data acquired over a kaolinitic terrain across the globe.

Radioactivity in building materials in Iraq

Activity concentrations of (226)Ra, (232)Th and (40)K in 45 samples of different building materials used in Iraq were measured using gamma-spectroscopy system based on high-purity germanium detector with an efficiency of 40 %. Radium equivalent activity, air-absorbed dose rate, annual effective dose, external and internal hazard indices and alpha index due to radon inhalation originating from building materials were measured to assess the potential radiological hazard associated with these building materials. The activity concentrations of the natural radionuclides (226)Ra, (232)Th and 40K were found to range from below detection limit (BDL) to 223.7 ± 9, BDL to 93.0 ± 3 and BDL to 343.1 ± 12, respectively. Values of average radium equivalent activity, air-absorbed dose rate, indoor and outdoor annual effective doses, external and internal hazard indices and alpha index ranged from 6.5 to 124.9, 16.2 to 89.5 (nGy h(-1)), 0.08 to 0.44 mSv, 0.02-0.11 mSv, 0.09 to 0.53, 0.13 to 0.69 and 0.03 to 0.62, respectively. These values indicate a low dose. Therefore, the building materials used in the current study are quite safe to be used as building materials.

Natural radioactivity of materials used in industry and construction in Serbia

Four different kinds of materials (feldspar, gypsum, clay and kaolin) commonly used in building construction and industry in Serbia were analyzed for their natural radioactivity, using gamma spectrometry. The radium equivalent activity, Ra(eq), the absorbed dose rate, D, the annual effective dose, D(E), and the external hazard index, H(ex), were evaluated to assess the radiation hazard for people living in dwellings made of the materials studied. The radium equivalent activities calculated in all samples are lower than the maximum admissible value 370 Bq kg(-1) set in the UNSCEAR report. The absorbed dose rate in air was found to vary from 0.02 to 0.19 μGy h(-1). Considering the fact that the average gamma dose rate indoors in Europe is 0.07 μGy h(-1), gamma dose rate calculated for feldspar, clay and kaolin samples exceed this limit. The obtained results for annual effective dose exceed limits of 0.41 mSv for feldspar, clay and kaolin samples. If the H(ex) exceeds unity, we might conclude that the potential external dose(s) to exposed individual(s) will exceed the acceptable level, and some action may be required. The obtained values of H(ex) are lower than unity for all investigated samples. All samples were measured immediately after preparation, except 10 samples of feldspar, because a comparative analysis were made between 215 samples which were measured immediately after preparation and 10 samples which were measured after radioactive equilibrium was reached in order to detect differences in the obtained concentrations.