Uranium from Africa has long been a major source of fuel for nuclear power and atomic weapons, including the bomb dropped on Hiroshima. In 2002, George W. Bush claimed that Saddam Hussein had "sought ...significant quantities of uranium from Africa" (later specified as the infamous "yellowcake from Niger"). Africa suddenly became notorious as a source of uranium, a component of nuclear weapons. But did that admit Niger, or any of Africa's other uranium-producing countries, to the select society of nuclear states? Does uranium itself count as a nuclear thing? In this book, Gabrielle Hecht lucidly probes the question of what it means for something--a state, an object, an industry, a workplace--to be "nuclear." Hecht shows that questions about being nuclear--a state that she calls "nuclearity"--lie at the heart of today's global nuclear order and the relationships between "developing nations" (often former colonies) and "nuclear powers" (often former colonizers). Nuclearity, she says, is not a straightforward scientific classification but a contested technopolitical one.Hecht follows uranium's path out of Africa and describes the invention of the global uranium market. She then enters African nuclear worlds, focusing on miners and the occupational hazard of radiation exposure. Could a mine be a nuclear workplace if (as in some South African mines) its radiation levels went undetected and unmeasured? With this book, Hecht is the first to put Africa in the nuclear world, and the nuclear world in Africa. Doing so, she remakes our understanding of the nuclear age.
Graphitic carbon nitride (g-C.sub.3N.sub.4) has been paid increasingly attentions in U(VI) removal due to the visible-light response, whereas the high recombination of photogenerated electron and ...holes limited the actual environmental application. Herein, Z-scheme MoS.sub.2/g-C.sub.3N.sub.4 heterojunction was fabricated to enhance removal of U(VI) from aqueous solution. The microscopic and spectroscopic characterizations showed that addition of MoS.sub.2 on surface of g-C.sub.3N.sub.4 increased separation efficiency of photogenerated charge, decreased the bandgap and improved the intensity of light adsorption. Approximate 82% of UO.sub.2.sup.2+ was photo-reduced by MoS.sub.2/g-C.sub.3N.sub.4 after 1 h of light irradiation at pH 4.5. The high effective photocatalytic reduction of U(VI) on MoS.sub.2/g-C.sub.3N.sub.4 was attributed to ·O.sub.2.sup.- radials according to quenching experiments. XPS analysis showed that the adsorbed U(VI) was photo-reduced into U(IV). These findings are crucial for the design of C.sub.3N.sub.4-based composites with high efficient photocatalytic performance and exclusive selectivity into actual environmental cleanup.
The MoS.sub.2@TiO.sub.2 hollow sphere heterostructures (MoS.sub.2@THS) were synthesized and used for photocatalytic reduction of U(VI) from wastewater under visible light. The optimum ...MoS.sub.2@THS-12 shows the highest photocatalytic reduction rate (irradiated for 80 min) with excellent recyclability and stability, which is approximately 4.1 times as much as the pure MoS.sub.2. The improved photocatalytic activity of MoS.sub.2@THS-12 is mainly due to the II-types heterojunction formed between MoS.sub.2 and THS. Meanwhile, the photogenerated electrons and superoxide radical are important active species in the photoreduction U(VI) process. The results provide an effective strategy for uranium resource utilization and pollution abatement.
In this study, an investigation has been carried out on the potential of radon, thoron and natural radioactive content by collecting soil samples from the Deccan land of Kolhapur district, India. The ...mean value of radon mass exhalation rates is 12.66 ± 1.07 mBqkg.sup.-1h.sup.-1 and mean thoron surface exhalation rate is 2300 ± 261 Bqm.sup.-2h.sup.-1. The mean value of Radon emanation factor is 5.18%. The mean activity concentrations of .sup.238U, .sup.232Th and .sup.40K in the soil samples are 9.33 ± 0.45 Bqkg.sup.-1, 16.60 ± 0.77 Bqkg.sup.-1 and 66.15 ± 4.33 Bqkg.sup.-1 respectively and well below the value recommended by UNSCEAR 2000.
In this work, a direct determination of .sup.238Pu determination using reactive gases, CO.sub.2 and H.sub.2 in triple quadrupole ICP-MS without prior radiochemical separation resins has been ...established. Quantification of 0.25 pg/mL .sup.238Pu sample mixture (1.18 pg of .sup.238Pu) yielded satisfactory results (> 95% accuracy), uncertainties of less than 15% and in the presence of spiked natural U (0.5 ng/mL). Additional verification of this method was performed using certified ratio materials (IRMM-086, Belgium) and experimental .sup.238Pu/.sup.239Pu and .sup.240Pu/.sup.239Pu values are analogous to the certified values provided.
This article describes the features and migration patterns of natural long-lived heavy radionuclides sup.238U and sup.226Ra in the major components of the environment including rocks, river waters, ...soils, and vegetation of permafrost taiga landscapes of Southern Yakutia, which helped us to understand the scale and levels of their radioactive contamination. Different methods have been used in this study to determine the content of sup.238U and sup.226Ra in various samples, including gamma-ray spectrometry, X-ray spectroscopy, laser excited luminescence, and emanation method. It was determined that the main source of radioactive pollution of soil and vegetation cover, as well as surface waters in these technogenic landscapes, are the dumps of radioactive rock that were formed here as the result of geological exploration carried out in this area during the last third of the 20th century. The rocks studied were initially characterized by a coarse, mainly stony gravelly composition and contrasting radiation parameters, where the gamma radiation exposure rate varied between 1.71 and 16.7 µSv/h, and the contents of sup.238U and sup.226Ra were within the range 126–1620 mg/kg and 428–5508 × 10sup.−7 mg/kg, respectively, and the sup.226Ra: sup.238U ratio was 1.0. This ratio shifted later on from the equilibrium state towards the excess of either sup.238U or sup.226Ra, due to the processes of air, water, and biogenic migration. Two types of sup.238U and sup.226Ra radionuclides migration were observed in studied soils, namely aerotechnogenic and hydrotechnogenic, each of which results in a different intraprofile radionuclide distribution and different levels of radioactive contamination. In this study, we also identified plants capable of selective accumulation of certain radionuclides, including Siberian mountain ash (Sorbus sibiricus), which selectively absorbs sup.226Ra, and terrestrial green and aquatic mosses, which accumulate significant amounts of sup.238U.
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![Migration of [sup.238]U and...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/2073-4441/small "Migration of [sup.238]U and [sup.226]Ra Radionuclides in Technogenic Permafrost Taiga Landscapes of Southern Yakutia, Russia")