Radioactivity measurement of primordial radionuclides in and dose evaluation from marble and glazed tiles used as covering building materials in Turkey

Evaluation of radiological health risk caused by the use of fly ash in cement and concrete production and its storage

As a result of firing pulverized coal in thermal power plants, enormous amounts of fly ash (FA) are produced as industrial waste. The release into the atmosphere and storage of this industrial waste remains one of the major environmental problems that threaten human health by contributing to air, water, and soil pollution. The recovery and reuse of FA in the construction industry is the only economic solution to the existing problem. In this study, the potential radiological risk caused by the usage of FA in concrete and cement production as a main component and its storage in landfill sites was evaluated for people and works by estimating radiological parameters (activity concentration and alpha index, annual effective doses, and the corresponding excess lifetime cancer risks) based on activity concentrations of terrestrial radionuclides in FA. Also, the radiological risk to the workers working in the FA landfill site was evaluated using the Residual Radioactivity Onsite 7.2 code. The average activity concentrations of terrestrial radionuclides in FA samples from the Tunçbilek lignite coal-fired thermal power plant at Kütahya province of Turkey were measured as 417, 156 and 454 Bq kg-1 for 226Ra, 232Th and 40K, respectively. When using up to 35% by mass of FA in cement and concrete, the average values of the radiological parameters revealed that they were within the recommended safety limits. However, code estimations showed that a regular worker in FA storage would be exposed to a total effective dose rate greater than 3 mSv y-1.

Radiological assessment of urban soil samples in the residents of a central Anatolian volcanic province, Turkey

The concentration of natural and anthropogenic radionuclides, emanation fraction (EF), and mass (χM) and area (χA) exhalation rate of 222Rn in urban soil samples collected from dwelling areas in Nevşehir city located in a region known as the central Anatolian volcanic province of Turkey were determined using gamma-ray spectroscopy. The average activity concentrations of 226Ra, 228Ra, 40K and 137Cs were measured as 60.2 ± 3.8, 50.1 ± 2.8, 631.0 ± 29.7 and 5.5 ± 0.4 Bq/kg, respectively. The average concentration of 222Rn in soil and air was estimated as 27 kBq/m3 and 84 Bq/m3, respectively. The average values of EF, χM and χA were found as 20%, 25.4 μBq/kg⋅s and 20.2 mBq/m2⋅s, respectively. The average values of outdoor absorbed gamma dose rate, external and internal annual effective dose and lifetime cancer risk estimated for radiological assessment were found as 85 nGy/h, 104 µSv/y, 797 µSv/y and 4.1 × 10-4, respectively.

Evaluation of terrestrial radionuclide levels and concomitant radiological risks of bentonites used in many industries

Bentonite is a soft, porous, easily shaped, and absorbent material rich in aluminum, sodium, and potassium. Bentonite is a mineral widely utilized as drilling mud, ore pelletizing, absorbent/adsorbent, bleaching agent, water impedance, coating, and raw material in various industries. In this study, radiometric measurements of 90 bentonite samples collected from 21 quarries in Turkey were performed using gamma-ray spectrometry. The radiological hazards caused by indoor exposure to adults due to the utilization of bentonites as raw materials in the construction industry and outdoor external exposures to quarry workers were evaluated by estimating the activity concentration index, annual effective doses, and lifetime cancer risk. The average activity concentrations of 226Ra, 232Th and 40K measured in bentonite samples were found as (50 ± 5) Bq/kg, (76 ± 4) Bq/kg and (373 ± 19) Bq/kg, respectively. The evaluation results reveal that the bentonites examined could be safely utilized as raw materials.

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.

Analytical evaluation of natural radionuclides and their radioactive equilibrium in raw materials and by-products

An investigation into the distribution of natural radionuclides and radioactive secular equilibrium in raw materials and by-products in a domestic distribution was conducted to deduce the optimum conditions for the analytical evaluation of natural radionuclides for (238)U, (226)Ra, and (232)Th using a gamma-ray spectrometer and inductively coupled plasma mass spectrometer (ICP-MS). The range of the specific activities of natural radionuclides was first evaluated by analyzing (228)Ac and (214)Bi, which are (232)Th and (226)Ra indicators, respectively, in about 100 samples of raw materials and by-products through a gamma-ray spectrometer. From further experiments using several samples selected based on the results of the distribution of natural radionuclides, the validation of their analytical evaluations for the indirect measurements using a gamma-ray spectrometer and direct measurements using ICP-MS was assured by comparing their results. Chemically processed products from the raw materials, such as Zr sand and ceramic balls, were generally shown for the type of bead and particularly analyzed showing a definite disequilibrium with above a 50% difference between (238)U and (226)Ra in the uranium series and (232)Th and (228)Ra in the thorium series.

Natural radioactivity and radiological hazard assessment of soil using gamma-ray spectrometry

Natural radioactivity in soil samples collected from different places of Bulandshahr, Hapur and Meerut city of Uttar Pradesh, India, using a low-level counting multichannel gamma-ray spectrometer system comprising an NaI(Tl) crystal. The range of (238)U, (232)Th and (40)K activity concentrations varied from 29.6 to 69.2, from 34.9 to 93.8 and from 438.2 to 719.9 , respectively. The activity concentrations of (232)Th are higher than those of (238)U in all the samples. The absorbed dose rate ranges from 53.18 to 110.95 . The values of the annual effective dose indoors are found to vary from 0.26 to 0.54 , whereas outdoors are found to vary from 0.07 to 0.14 . The annual effective dose is marginally below the international recommended value of 1 for the general public. The external and internal hazard indexes of the soil samples are below the recommended limits. The values of the gamma index in soil samples varied from 0.41 to 0.88. The values of the alpha index varied from 0.15 to 0.35. All these values of and are <1.0. It is observed from the results that there is no significant radiation hazard due to natural radionuclides of the soil samples in the studied areas.