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[en] The Taquari River Basin, located in the Alkaline Complex of Poços de Caldas, in the south of Minas Gerais, Brazil, is situated in an old volcanic caldera. In the study area there are fields and pastures; agriculture with cultivation of vegetables; rose plantations; and native forest, in addition to the Mineral Treatment Unit of Caldas (UTM-Caldas), which is part of the Industrial Complex of Poços de Caldas (CIPC), a uranium mining and processing facility. The main objective of this work was to investigate the isotopic Pb signatures of river sediments, rocks, mining tailings and fertilizer samples collected in the region surrounding UTM-Caldas in order to identify environments with influences from geogenic and / or anthropogenic sources. The results showed that there is an anthropic contribution (fertilizers and mining tailings) in some sectors of the Taquari river basin, generating possible concerns about the amount of elements that can be transferred to the water bodies. In addition, there is a significant geogenic contribution of naturally enriched areas, which have distinct situations that also generate an increase in the concentration of chemical elements in water bodies. (author)
[en] Natural radioactivity is widespread in the terrestrial environment and is mostly related to the presence of radionuclides in the soil. The objective of this dissertation is to characterize the spatial distribution of natural radionuclides in the soil and to evaluate the potential risks associated with radiation exposure in an area of uranium mineralization in southwest Bahia. The study area called Caetité Experimental Basin (CEB), has an area of 75km2 and includes the only active uranium mining and milling installation (URA) in the country. The radionuclides 238U, 226Ra, 232Th, 228Ra and 40K were determined in 44 soil samples by non-destructive (gamma spectrometry) and destructive (radiochemical and ICP-MS) methods and the potential radiological risks were assessed using the absorbed dose, annual effective dose, excess lifetime cancer risk, radium equivalent activity (Raeq), and external hazard index (Hex). The results showed that the radionuclides from the 238U and 232Th decay series in soils are not in secular equilibrium. 40K is the dominant radionuclide and is associated with primary minerals from granitic and gneiss rocks, while radionuclides from the 238U and 232Th decay series occur mainly associated with accessory minerals or affiliated with uranium mineralization. Cambisol is the soil class where the highest concentrations of radionuclides of interest are observed. The activity concentration of radionuclides from the 238U and 232Th decay series in the sub-basins with uranium anomalies is significantly higher than those observed in the sub-basins without anomalies. It was not possible to observe the impact of the URA activities in increasing the concentration of radionuclides in soils. The average value of the gamma dose rate is higher than the world average, but still within the range. The average annual effective dose is 1.6 times higher than the world average and the estimated excess lifetime cancer risk is 0.397 × 10-3. Both the Raeq and Hex were below the reference values used internationally to assess radiation exposure due to the use of construction materials. Thus, it can be concluded that the distribution of the activity concentration of the radionuclides in the BEC soils is controlled by geology, with the values obtained being comparable to the values reported in soils from different countries. From the radiological point of view, the outdoor gamma radiation doses found are relatively low, and most soils in the region can be used as construction material, according to the radiological indexes (Raeq and Hex). (author)
[en] Conclusion: In conclusion, the assessment of the current third generation reactors with regard to low level of CO2 emission is already remarkable, and this energy is the most efficient in this field. The additional gain that fourth-generation reactors could bring to decrease the global level of CO2 emission would be first to be able to supplement the offer on the heat market to replace fossil fuels, in particular for some high-temperature industrial needs. The flexibility of SMR concept should be useful to help to replace some fossil fuels utilization. The other potential long-term gain is the possibility of being able to operate without the need for uranium mines and all subsequent CO2 production due to downstream activities from mining, transportation and enrichment.
[en] In this work, a total of twenty samples selected for investigation originate from South Africa and Namibia uranium mines. The aim of this study was to determine whether the lead ratios measured in particular samples could be used to attribute the uranium sample to the production or reprocessing plant. Measurements were carried out using an inductively coupled plasma mass spectrometer PerkinElmer NexION 2000. The precision obtained for the 208Pb/206Pb ratio, the 207Pb/206Pb ratio and the 204Pb/206Pb ratio values was considerably lower than 0.02% demonstrating the applicability of the technique for Pb isotope ratio studies. (author)
[en] In the context of proposed uranium mining area, it is very important to evaluate the presence of certain trace metals in groundwater around a proposed uranium mining area at Peddagattu and Seripally areas of Nalgonda district, Telangana (India). The concentrations of certain metals (Cu, Zn, Ni, Pb, Fe, Mn, Cd, Co, Sr, Ba, Cr, Cs and As) were measured in 37 groundwater locations and 10 surface water locations for seven times during 2 years around proposed uranium mining areas. The risk of the chemical toxicant [may be characterized using a hazard quotient (HQ)] is calculated by the results obtained during the study. The HQs of both groundwater (37) and surface water (10) all the considered trace metals were well below the threshold value of 1 as suggested by USEPA.
[en] In the 1990, radon and radon progeny was reported to contribute approximately 70% of the average 1.4 + 1.0-mSv annual dose across 26 Western Australian underground non-uranium mines. The Western Australian underground mining workforce has expanded significantly, and parameters used to calculate doses have changed significantly, warranting a review of the 1990's data. The review concludes that doses received by the contemporary mining workforce has increased on average, by 5.4%, with annual dose estimates ranging from 0.53 to 3.56 mSv, with a mean of 1.33 mSv. Doses in 12 of the 23 underground mines exceed 1 mSv and are required to comply with radiation safety legislation. It is estimated that 5400 underground workers will fall into the greater than 1-mSv category. The collective dose to the underground worker population has increased by 4.5 times from 3060 man mSv (2173 workers) to 13 669 man mSv (8597 workers). (authors)
[en] Rare earth elements (REE) are used for different applications worldwide in new technologies considered critical and strategic materials in the current globalized scenario and the concern about this resource is constantly gaining attention. The search for new sources of REE is a current issue and researchers are seeking for recycling and recovering REE from secondary sources. Acid mine drainage (AMD) is an important secondary source of REE because this effluent can contain a considerable amount of these precious elements. Furthermore, as AMD is a serious environmental issue and demands treatment before discharge, the union of metal recovery and pollution control is something desirable when sustainability is the goal. There is a closed uranium mine in the state of Minas Gerais-Brazil, with the occurrence of an REE-rich AMD. This peculiar site was selected due to its sui generis geochemical characteristics. In this scenario, this investigation aimed to evaluate the co-precipitation of REE from AMD effluents using oxyhydroxides of Al and Fe as the major co-precipitants. A geochemical model of the AMD system indicates that Ln3+, LnSO4+ and LnF2+ are the dominant REE species at pH 3.5. The neutralization of the AMD with KOH produced an amorphous precipitate containing 14% of REE oxides. The precipitate contains Al13-polymers and accounts for the REE removal when the pH is raised to 8, thus promoting adsorption and entrapment simultaneously. Sequential extraction revealed that 60% of the REE could be leached with the use of acetic acid. In sequence, the role of iron in the coprecipitation of REE and uranium by Fe-Al-precipitates in AMD was studied. It was concluded that the presence and the amount of Fe in the initial solution can positively influence the REE removal efficiency, especially at acidic environments. The influence caused by the addition of Fe was irrelevant when the pH of the AMD was raised to values equal to 7-8. The removal of U was not influenced by the addition of Fe to the AMD before pH neutralization. Sequential extraction results showed that precipitates containing higher amounts of Fe, the REE tend to be less labile. 57Fe Mössbauer spectroscopy studies revealed that the REE can occupy iron sites in the structure of the amorphous precipitates. Subsequently, the influence of soluble Ca and Zn over the co-precipitation of REE by amorphous aluminium precipitates was studied. It was concluded that Ca exerts a negative influence over the co-precipitation as well as over the adsorption of Pr and Eu on amorphous aluminium precipitates. On the other hand, the coprecipitation and adsorption of the elements Nd and Sm did not suffer any influence of the presence of Ca in the solution. Finally, a study concerning the recovery of REE by co-precipitation with Al13-polymers from AMD using Ca(OH)2 for pH control showed that about 90% of the REE present in the AMD sample could be recovered by co-precipitation with amorphous Al-precipitates. The precipitate contains about 7% of REE oxides. The results of the acid-leaching experiment show that about 60%, 65% and 85% of the REE can be extracted from the precipitates using 2 mol L-1 HCl, 1.7 mol L-1 H2SO4 and 2 mol L-1 CH3COOH, respectively. The economic potential of the REE-recovery considering an AMD sample from the studied site was also estimated, revealing the great potential of AMD treatment combined with REE production, in compliance with the United Nations sustainable development goals. (author)
[en] Fundamental estimates of radon-associated health risk have been provided by epidemiological studies of miners. In total, approximately 15 studies have been conducted worldwide since the 1960s. These results have contributed directly to radiological protection against radon. The present article summarises the main results, with a focus on analyses of miners exposed more recently, estimates of radon lifetime attributable risk, and interaction between radon and smoking. The potential for the upcoming Pooled Uranium Miner Analysis project to further improve our knowledge is discussed. (author)
[en] The town of Zhovti Vody is a 'capital' of uranium mining and processing industry of Ukraine. The mining and processing of uranium has been carried out in this area for more than 60 y. During this period, due to increasing production activities, the town has grown significantly. As a result of production activities and also due to the human factor, the territory of the town was contaminated by radioactive rocks. In addition, out of ignorance, radioactive rocks were used in the construction of houses and roads. To normalize the radiation situation in the town, a targeted State Programme was adopted in 2003 for a period of 10 y. In 2013, the Programme was subsequently extended until 2022. In accordance with this Programme, decontamination of the urban territory, measurements of radon isotopes in houses and anti-radon reconstructions of the premises have been performed. The results of these works are described in this article. (authors)
[en] Orano delivered solid results in 2019 with a return to revenue growth, an increase in the EBITDA supported by successful implementation of its performance plan and a positive net cash flow after a voluntary contribution enabling a return to 100% coverage of its dismantling liabilities. By improving its financial outlook for 2020, the Group is confirming its role as a major player in the low carbon nuclear energy industry, which has its part to play in the fight against climate change. Robust operating performance: Revenue of Euros 3,787 million, up +4.5% compared with 2018 (+3.7% like-for-like); EBITDA margin of 23.7% (22.7% in 2018) supported by the performance plan. Net cash flow from company operations very positive: Net cash flow of Euros 219 million, up compared with 2018 (Euros 158 million); A voluntary contribution of Euros 134 million to earmarked assets brought the coverage rate of end-of-life-cycle liabilities up to 100%. Big increase in net income attributable to owners of the parent: Net income attributable to owners of the parent of Euros 408 million (loss of Euros 544 million in 2018), reflecting the high return on earmarked assets and the good operating momentum; Adjusted net income attributable to owners of the parent of Euros 145 million loss (profit of Euros 72 million in 2018), penalized by the impact of the drop of the rates in 2019 and by the non-recurring cost of the debt refinancing transaction for a total of Euros 150 million. Improved 2020 financial outlook: Increase in the anticipated EBITDA margin to between 23% and 26% (vs. between 21% and 24%); Continued revenue growth