γ-Spectrometric determination of the content of natural radionuclides in natural waters

Mukhamedov, A. K.; Poteshkin, G. V.; Салихбаев, У. С.; Khazratov, T. Kh.; Dorofeev, A. A.; Muminov, T.M.; Rashidova, D. Sh.; Kholbaev, I.

doi:10.1007/bf02672932

Cited by 5 publications

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“…The low-intensity component 235 U in the spectrum can be determined from the difference of the spectra (1) and (2). The statistical and methodological errors in the determination of the radionuclides in the samples as a function of their activity are shown in Fig.…”

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Radioactivity of Natural Waters in Nurabad District of Samarkand Region

Azimov

Safarov

et al. 2015

At Energy

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The 222 Rn content in natural waters is determined, as a rule, according to the α-activity of the gas emitted from the water and all other radionuclides in the uranium-thorium families and 40 K by the gamma-spectrometric method and by radiochemical separation the isotopes being analyzed or evaporation of water samples to dry residue [1].In the present work, gamma spectrometry was used to investigate the content of natural radionuclides in water samples from springs, dug wells, boreholes, rivers, lakes, and water reservoirs in the Nurabad district of Samarkand region.Sample Preparation and Measurement Procedure. Samples were obtained from 43 natural sources located in different parts of the Nurabad district, which differ by the geophysical characteristics of the locale. To determine the specific activity of 222 Rn, the water samples were hermetically packed in a Marinelli vessel immediately after extraction (samples s).The evaporation losses of radon in the process of extraction and packaging of the samples s did not exceed 10% (Fig. 1) [2]. Concentrated samples prepared by evaporating water samples with volumes ranging from 10-50 liters to 1 liter at temperature ~70°C to a dry residue (samples p) were used to determine the specific activity of long-lived 226 Ra, 232 Th, and 40 K. The radioactive equilibrium of 226 Ra was restored in the p samples after a holding period of approximately 40 days. Samples ƒ of distilled water were prepared to determine the background component in the instrument spectra. All samples were packed in standard one-liter Marinelli vessels.The investigations were performed using a gamma spectrometer with a 63 × 63 mm NaI(Tl) detector, placed inside 10-cm thick lead shielding, with energy resolution ~7% on the 1332 keV line. The gamma spectrometer was calibrated in terms of efficiency using the standard 226 Ra, 232 Th, and 40 K sources from the OMASN set with filler density ρ 1 = 0.86-0.96 and ρ 2 = 1.64-1.86 kg/liter. The accumulation and processing of the instrument spectra were accomplished using standard spectrometric apparatus and software package. The γ-spectra were processed by the procedure of [3], which makes it possible to adjust the instability of the characteristics of the analog spectrometric apparatus.The determination of the activity of the natural radionuclides in the water samples by the gamma-spectrometric method is complicated by the fact that the instrument spectrum of the background component is formed by the same radionuclides as in the samples used for analysis. In addition, as a rule, the intensity of the background spectrum is much greater than that of the analyzed radionuclides. These difficulties can be overcome to a large extent by systematic decomposition of the initial spectra into individual components (Fig. 2).The γ-spectrum of the s samples is a superposition of the spectra of 226 Ra, 232 Th, 235 U, and 40 K as well as the background spectrum F: S 0 = S(Rn) + S(Ra) + S(U) + S(F) + S(K) + S(F).

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Radioactivity of Natural Waters in Nurabad District of Samarkand Region

Azimov

Safarov

et al. 2015

At Energy

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“…The spectrometer was calibrated with respect to the γ-ray detection efficiency using standard volume sources (OMASN) of 40 K, 137 Cs, 226 Ra, and 232 Th. The measurement procedure is described in detail in [5].…”

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Elemental composition and radioactivity of Turkestanian colcothar

et al. 2004

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Colcothar is a solid pitch-like substance with a shiny surface ranging in color from dark brown to black, with a specific smell and bitter taste. It is a mixture of organic and inorganic substances which are usually soluble in water. Since ancient times it has been used for treating many sicknesses, and its origin (animal, plant, petroleum, deep, excrement, bee, mineral, and so on) is still unknown [1,2].In the present work, the elemental composition of colcothar obtained from 10 samples of raw material taken from a cave in paleozoic rock on the northern slopes of the Turkestan mountain range was investigated. The samples were obtained by repeatedly extracting the initial material using water followed by evaporation. The organoleptic indicators of the samples -20-22.5% mineral, 71.1-77.9% organic, 2.1-6.4% moisture -are characteristic for many types of colcothar [2].Measurement Procedure. Results. The content of chemical elements (see Table 1) was determined by the following methods:• instrumental neutron-activation analysis with irradiation of the samples (50 mg) with thermal neutrons with flux density 6·10 12 sec -1 ·cm -2 in the VVR-SM reactor at the Institute of Nuclear Physics of the Academy of Sciences of the Republic of Uzbekistan [3]; • atomic-absorption analysis on a Hitachi (Japan) Z-8000 spectrophotometer;• emission-spectral analysis on a DFS 8 diffraction spectrograph; • chemical quantitative analysis used in geological practice [4]. These methods determined in 10 samples of colcothar, as a whole, the content of 44 elements to within 5-30%. The variance in the content of most elements in the samples does not exceed a factor of 3-4, but it reaches 10 for selenium and thorium.Since the content of natural radionuclides from the uranium-thorium series is low in colcothar, the radioactivity of colcothar was determined for a collection of all ten samples (total mass 1200 g). The specific activity of 40 K, 226 Ra, and 228 Ac in the sample is 2010, ≤1, ≤2 Bq/kg, respectively. The measurements were performed on a γ spectrometer with a Ge(Li) detector (V = 100 cm 3 , ∆E γ~ 6 keV at E γ = 1332 keV) in the geometry of a one-liter Marinelli vessel. In the γ spectrum of colcothar the total absorption peaks for γ radiation from 226 Ra ( 238 U series), 228 Ac ( 232 Th series), and their daughter radionuclides are comparable in intensity with the background spectrum, while the 1461 keV γ radiation from 40 K is more than 4 times higher than the background value. The spectrometer was calibrated with respect to the γ-ray detection efficiency using standard volume sources (OMASN) of 40 K, 137 Cs, 226 Ra, and 232 Th. The measurement procedure is described in detail in [5].

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