Activity Concentrations Of Uranium Isotopes Research Articles

Uranium isotopes in food and effect on health of Southern Kazakhstan citizens

ABSTRACT Natural uranium isotopes were determined in food products of the Kyzylorda region in Kazakhstan. This region is characterised by the influence of the uranium industry, as up to 15% of the world uranium reserves are concentrated in this part of Kazakhstan and the adjacent territory of Kyrgyzstan. The food products most consumed by locals were selected for this survey. Special attention was paid to the analysis of edible and non-edible parts of food products and the assessment of a possible increase in risk due to consumption of non-edible parts. The highest content of uranium, of 80.2 µg/kg, was found in the edible part of the carrot. The highest activity concentrations of uranium isotopes are found in carrot, potato and onion, as edible parts of these vegetables are grown in the soil. All estimated cancer risks for uranium isotopes range from 10−14 to 10−12, which are insignificant values.

Uranium isotopes in groundwater in Ho Chi Minh City and related issues: Health risks, environmental effects, and mitigation methods

Groundwater is regularly used for many purposes, such as drinking and agricultural irrigation systems. Still, it contains high levels of radionuclides (e.g., 238U, 232Th, and 226Ra) that are potentially hazardous to humans and the environment. In this study, activity concentrations of uranium isotopes were analyzed in 15 groundwater samples taken from 15 bored wells in Thu Duc district, Ho Chi Minh City, Vietnam. Environmental effects of the irrigation system with groundwater on agricultural soil in the study area were assessed by models. It was found that the activity concentrations of 238U and 234U in groundwater samples were in the ranges of (13.5-268.7) mBq l-1 and (20.2-438.3) mBq l-1, respectively. The ratio 234U/238U values were ranged from 1.12 to 2, with an average value of 1.44. Based on the model prediction, 25years irrigation with the groundwater can inject 94.8Bq both uranium isotopes in 1kg topsoil. For investigated groundwater samples, the proposed removal method using K2FeO4 removed 74.28% and 81.04% for 234U and 238U, respectively.

Sample matrix influence on the efficiency function modeling for uranium isotopes determination by gamma spectrometry

The aim of the presented study was to explore the influence of precise determination of sample matrix in order to obtain reliable gamma spectrometry results. The test was done using two different approaches which have the same goal: quantifying the activity concentration of uranium isotopes in different samples found in the former uranium ore deposit Mazdreja. The first approach is based on iterative methodology, which utilizes the characteristic of a sample that can be quantified before gamma spectrometric measurement. Density of the sample and calculated mass fractions of its constituents (which vary in each iteration) can help to obtain the efficiency function from which activity concentrations of 235 U and 238 U can be derived and corresponding masses of uranium for the next iteration. In this approach LabSOCS software is used in order to obtain appropriate efficiency. The second approach that was tested represents semiempirical method which applies Monte-Carlo simulations through Geant4 and EFFTRAN software codes for the purposes of generating the detection efficiency functions needed for further calculations. The idea was to compare different methods for uranium activity concentration determination in sample matrices with high uranium mass content and also establish the need for precise calculation (described within the iterative method) by quantifying the relative deviation in activities, calculated by using different methods. From the obtained results, it can be seen that it is very important to adjust the sample matrix to correct composition if we need a precise gamma spectrometry result. But if there is a need to get results in a short period of time, then for the estimation of the activity concentration of the analyzed sample an approximate sample composition can be used. All three tested analyzed methods gave comparable results inside 15% of difference. The major difference was obtained by EFFTRAN software, but on the other side this software is user-friendly and the results can be obtained faster than by using other analysis methods presented in this study. • Testing the influence of precise determination of sample matrix. • The analyzed samples were from former uranium ore deposit Mazdreja. • One approach was Iteration method with LabSOCS software. • The second approach was GEANT4 and EFFTRAN software analysis. • Comparison of different methods for uranium activity concentration.

Radioactivity content in volcanic rocks and radionuclides transfer from rocks to groundwater at Mt. Etna volcano

The paper presents the results of a radiological survey carried out on the eastern flank of Mt. Etna over an area of approximately 120 km 2 . Activity concentrations of uranium isotopes 238,234 U, thorium isotopes 232,230,228 Th, two radium isotopes 226,228 Ra from 238 U and 232 Th decay chains and potassium 40 K were determined using the a- and g- nuclear spectrometry techniques. All rock samples presented activity concentrations of U, Th and Ra in the range between 20 Bq/kg to about 90 Bq/kg, showing a comparable radioactivity content in the whole investigated area. Based on their respective elemental concentrations, the isotopic ratios between different isotopes were studied to draw conclusions on the presence of radioactive equilibrium or disequilibrium in the decay chains. Moreover, an attempt to calculate radionuclide transfer factors from soil to water was made. On the basis of the evaluated concentrations, the radiological risk resulting from ingestion of these isotopes with drinking water was calculated. The obtained results were compared with the regulations currently in force regarding the quality of drinking water.

234U/238U activity ratios in groundwaters from two aquifers in Saudi Arabia, and correlation with water chemistry

Abstract The purpose of this study was to determine the activity concentrations of uranium isotopes (234U and 238U) and the 234U/238U activity ratios in groundwater wells from Saudi Arabia. These wells are located in two different regions and tapping different aquifers. The uranium isotopes were measured by alpha spectrometry. The uranium activity ratios (234U/238U) in the investigated samples had an average value of 1.38 and ranged from 1.0 to 2.17. The relationship between the activity concentrations of the combined uranium and the water chemical composition in the studied wells was also investigated. Good correlation was found with redox potential described by R2 value of 0.74. Also, a good negative correlation was observed between The TDS content of the groundwater samples and the uranium activities described by R2 value of 0.59. Finally, with twenty groundwater samples collected from two large areas, the presence of uranium isotopes in the Saq and Dammam aquifers can't be easy to judge but within the framework of this study, it can be concluded that the distribution of 238U and 234U in these two aquifers is more dependent on the mineralogical composition of the aquifer matrix and by the geochemical/hydrochemical conditions present.

Concentration of uranium in the drinking and surface water around the WIPP site

Activity concentration of uranium isotopes (238U, 234U and 235U) were analyzed in drinking and surface water samples collected in the vicinity of the WIPP site using alpha spectroscopy. The purpose of this study was to investigate the changes in uranium concentrations (if any) in the vicinity of the WIPP site and whether the February 14, 2014 radiation release event at the WIPP had any detectable impact on the water bodies around the WIPP.

Natural radioactivity content in groundwater of Mt. Etna’s eastern flank and gamma background of surrounding rocks.

<p>Waters of Mt. Etna are the main source of drinking water for the local population and are also distributed in municipal supply systems to neighbouring areas. Radioactivity in underground waters and surrounding rocks from the eastern flank of Mt.Etnawas investigated on the basis of 9 water and 8 rocks samples from 12 localities altogether. Three samples were from water drainage galleries and six from water wells. All water intakes are used for consumption. Activity concentration of uranium isotopes <sup>234,238</sup>U, radium isotopes <sup>226,228</sup>Ra and radon <sup>222</sup>Rn were determined with the use different nuclear spectrometry techniques. The determination of uranium isotopes was carried out with the use of alpha spectrometry. The measurements of radium and radon activity concentration in water were performed with the use of a liquid scintillation technique. Additionally, rocks surrounding the intakes were examined with gamma spectrometry. All water samples showed uranium concentration above Minimum Detectable Activity (MDA), with the highest total uranium (<sup>234</sup>U + <sup>238</sup>U) activity concentration equal to 149.2±6 mBq/L. Conversely, all samples showed radium isotopes activity concentrations below MDA. Radon activity concentration was within the range from 2.91±0.36 to 21.21±1.10 Bq/L, hence these waters can be classified as low – radon waters. Gamma natural background of the rocks surrounding the water sampling sites was found on the same levels as other volcanic rocks of Italy.</p>

Precipitation and purification of uranium from rock phosphate

This study was carried-out to leach uranium from rock phosphate using sulphuric acid in the presence of potassium chlorate as an oxidant and to investigate the relative purity of different forms of yellow cakes produced with ammonia, magnesia and sodium hydroxide as precipitants, as well as purification of the products with TBP and matching its impurity levels with specifications of the commercial products. Alpha-particle spectrometry was used for determination of activity concentration of uranium isotopes in rock phosphate, resulting phosphoric acid, and in different forms of the yellow cake. Likewise, atomic absorption spectroscopy was used for determination of impurities. On the average, the equivalent mass concentration of uranium was 119.38 ± 79.66 ppm (rock phosphate) and 57.85 ± 20.46 ppm (phosphoric acid) with corresponding low percent of dissolution (48 %) which is considered low. The isotopic ratio (234U:238U) in all stages of hydrometallurgical process was not much different from unity indicating lack of fractionation. Upon comparing the levels of impurities in different form of crude yellow cakes, it was found that the lowest levels were measured in hydrated trioxide (UO3·xH2O). This implies that saturated magnesia is least aggressive relative to other precipitants and gives relatively pure crude cake. Therefore, it was used as an index to judge the relative purity of other forms of yellow cakes by taking the respective elemental ratios. The levels of impurities (Fe, Zn, Mn, Cu, Ni, Cd and Pb) in the purified yellow cake were found comparable with those specified for commercial products.

Determination of uranium isotopes in environmental samples

The determination of isotopes of uranium by alpha spectrometry in different environmental components (sediments, soil, water, plants and phosphogypsum) is presented and discussed in this paper. The alpha spectrometry is a very convenient and good technique for activity concentration of natural uranium isotopes (234U, 235U, 238U) in environmental samples and provides the most accurate determination of isotopic activity ratios between 234U and 238U. The analysis were provided information about possible sources of high concentrations of uranium in the examined sites determined by anthropogenic sources. The calculation of values 234U/238U in all analyzed samples was applied to identifying natural or anthropogenic uranium origin. Activity concentration of uranium isotopes in analyzed environmental samples shows that measurement of uranium levels is of great importance for environmental and safety assessment especially in contaminated areas (phosphogypsum waste heap).

Radioanalytical investigations of uranium concentrations in natural spring, mineral, spa and drinking waters in Hungary

Within this work, the activity concentrations of uranium isotopes (234U, 235U, and 238U) were analyzed in some of the popular and regularly consumed Hungarian mineral-, spring-, therapeutic waters and tap waters. Samples were selected randomly and were taken from different regions of Hungary (Balaton Upland, Bukk Mountain, Somogy Hills, Mezőfold, and Lake Heviz). Concentration (mBq L−1) of 234U, 235U, and 238U in the waters varied from 1.1 to 685.2, from <0.3 to 7.9, and from 0.8 to 231.6 respectively. In general, the highest uranium concentrations were measured in spring waters, while the lowest were found in tap waters. In most cases radioactive disequilibrium was observed between uranium isotopes (234U and 238U). The activity ratio between 234U and 238U varies from 0.57 to 4.97. The calculated doses for the analyzed samples of spring water are in the range 0.07–32.39 μSv year−1 with an average 4.32 μSv year−1. This is well below the 100 μSv year−1 reference level of the committed effective dose recommended by WHO and the EU Council. The other naturally occurring alpha emitting radionuclides (226Ra and 210Po) will be analyzed later to complete the dose assessment. This study provides preliminary information for consumers and authorities about their internal radiological exposure risk due to annual intake of uranium isotopes via water consumption.

Radioactivity in waters of Mt. Etna (Italy)

Abstract Radioactivity in underground waters from Mt. Etna was investigated on the basis of 13 samples. The samples were collected from springs, wells and galleries around the volcano. Water from nine out of thirteen intakes is used for consumption. Activity concentration of uranium isotopes 234,238U, radium isotopes 226,228Ra and radon 222Rn were determined with the use different nuclear spectrometry techniques. The measurements of radium and radon activity concentration were performed with the use of a liquid scintillation counter. The determination of uranium isotopes was carried out with the use of alpha spectrometry. All samples show uranium concentration above Minimum Detectable Activity (MDA), with the highest total uranium (234U + 238U) activity concentration equal to 130 mBq/l. For radium isotopes, all samples except one showed the activity concentration below MDA. Radon activity concentration was within the range from 1 to 13 Bq/l, hence these waters can be classified as low-radon waters.

Analytical methods for the characterization and the leachability evaluation of a solid waste generated in a phosphoric acid production plant

Abstract Naturally Occurring Radioactive Materials (NORM) are present in the environment and can be concentrated by technical activities, particularly those involving natural resources. These NORM deposits are highly stable and very insoluble under environmental conditions at the earth's surface. However reducing or oxidant conditions or pH changes may enable a fraction of naturally occurring radionuclides to eventually be released to the environment. In this paper the analytical methods to determine the chemical and radiochemical composition of a solid waste generated in an acid phosphoric production plant was shown. The sample, analysed by gamma spectrometry and radiochemical methods, contained 210Pb and 210Po and a high activity concentration of uranium isotopes but it shows a very low quantity of 226Ra. Also a sequential extraction method consisting of five operationally-defined fractions was used to evaluate the leachability of uranium isotopes, 210Pb and 210Po. The average leaching potential observed in the sample is 97.6% for 238U, 93.2% for 210Pb and 82.4% for 210Po. Moreover the results show that 210Pb and 210Po are leachable under only extreme conditions, whereas uranium is very more soluble.

Uranium and its decay products in samples contaminated with uranium mine and mill waste

The routine determination of the activity concentrations of uranium isotopes ( 238 U, 235 U and 234 U), thorium isotopes ( 232 Th, 230 Th and 228 Th), 231 Pa, 226 Ra, 210 Pb and 210 Po in the environment is one of the most important tasks in uranium mining areas. Natural radionuclides contribute negligibly to the external radiation dose, but in the case of ingestion or inhalation can represent a very serious hazard. The objective of this study was to determine the activities of uranium and its decay products 230 Th, 231 Pa, 226 Ra, 210 Pb and 210 Po in sediments and water below sources of contamination (uranium mine, disposal sites and individual inflows) using gamma and alpha spectrometry, beta counting, the liquid scintillation technique and radiochemical neutron activation analysis.