Evaluation of Solid Geologic Reference Materials for Uranium-Series Measurements via LA-ICPMS

Science.gov (United States)

Matthews, K. A.; Goldstein, S. J.; Norman, D. E.; Nunn, A. J.; Murrell, M. T.

2008-12-01

Uranium-series geochemistry and geochronology have a wide range of applications in paleoclimatology, volcanology and other disciplines. To further explore these fields, the geoanalytical community has now begun to exploit recent advances in in situ, micron-scale sampling via laser ablation-ICPMS. Unfortunately, improvements in instrumentation have generally outpaced development of the appropriate geologic reference materials required for in situ U-series work. We will report results for uranium and thorium isotopic ratios and elemental concentrations measured in a suite of solid standards from the USGS (e.g., BCR-2G, BHVO-2G, GSD-1G, MACS-1, NKT-2G), as well as those from the MPI-DING series (e.g., ATHO-G, T1-G, StHs6/80-G). Specifically created for microanalysis, two of these standards are synthetic (GSD-1G, MACS-1) and the remainder are naturally-sourced glasses. They cover a range of compositions, ages (± secular equilibrium), elemental concentrations and expected isotopic ratios. The U-series isotopics of some powdered source materials have been characterized (e.g., BCR-2, BHVO-2), although there is no confirmation of the same ratios in the glass. Bulk measurement of these solid standards via TIMS and solution multicollector-ICPMS can then be used to assess the performance of LA-ICPMS techniques which require matrix-matched solid standards for correction of U-series elemental and isotopic ratios. These results from existing, widely-available reference materials will also facilitate quantification and comparison of U-series data among laboratories in the broader geoscience community.

Behaviour of uranium series radionuclides in surface water (Crouzille, Limousin). Geochemical implications

International Nuclear Information System (INIS)

Moulin, J.

2008-06-01

Understanding natural radionuclides behaviour in surface water is a required step to achieve uranium mine rehabilitation and preserve water quality. The first objective of this thesis is to determine which are the radionuclides sources in a drinking water reservoir. The second objective is to improve the knowledge about the behaviour of uranium series radionuclides, especially actinium. The investigated site is a brook (Sagnes, Limousin, France) which floods a peat bog contaminated by a former uranium mine and which empties into the Crouzille lake. It allows studying radionuclides transport in surface water and radionuclides retention through organic substance or water reservoir. Radionuclides distribution in particulate, colloidal and dissolved phases is determined thanks to ultra-filtrations. Gamma spectrometry allows measuring almost all natural radionuclides with only two counting stages. However, low activities of 235 U series radionuclides impose the use of very low background well-type Ge detectors, such as those of the Underground Laboratory of Modane (France). Firstly, this study shows that no or few radionuclides are released by the Sagnes peat bog, although its radioactivity is important. Secondly, it provides details on the behaviour of uranium series radionuclides in surface water. More specifically, it provides the first indications of actinium solubility in surface water. Actinium's behaviour is very close to uranium's even if it is a little less soluble. (author)

Analyses of uranium series nuclides by alpha spectrometer on the uranium deposit

International Nuclear Information System (INIS)

Wismawati, T.

2000-01-01

The research is one of the program which was planned by PNC (Power Reactor and Nuclear Fuel Development Corporation). In this research the analyses of the uranium series nuclide of rock samples from uranium Tono deposit, Japan have been carried out. The 17 samples were collected from Tsukiyoshi Fault, at Gallery X on Shaft 2 consist of granite, sedimentary rocks and fault area. The aim of the research is to determine the area of U accumulation, equilibrium and leaching. The samples were treated by chemical reagent, separated by ion exchange resin and extracted by organic compounds. The uranium and thorium were deposited on the stainless steel plate surface by the electrolysis process. The activity of uranium and thorium was determined by alpha spectrometer. From the analyses data have been obtained that shows that the maximum activity of 238 U is 3.6798±0.1873 Bq/g, activity 234 U is 3.5450±0.1805 Bq/g and activity 230 Th is 3.6720±0.1868 Bq/g. The ratio figure 234 U/ 238 U versus 2 34 U / 2 30 T h has been drawn. As the conclusion, 6 samples point (No.3, 5, 8, 11, 13 and 16) lied in or on the boundary of the uranium accumulation area, 7 samples (No. 4, 6, 9, 10, 12, 15 and 17) are very close to the equilibrium position, 4 points (No. 1, 2, 7, and 14) in the leaching process. (author)

Uranium, thorium and potassium contents and radioactive equilibrium states of the uranium and thorium series nuclides in phosphate rocks and phosphate fertilizers

Energy Technology Data Exchange (ETDEWEB)

Komura, K; Yanagisawa, M; Sakurai, J; Sakanoue, M

1985-10-01

Uranium, thorium and potassium contents and radioactive equilibrium states of the uranium and thorium series nuclides have been studied for 2 phosphate rocks and 7 phosphate fertilizers. Uranium contents were found to be rather high (39-117 ppm) except for phosphate rock from Kola. The uranium series nuclides were found to be in various equilibration states, which can be grouped into following three categories. Almost in the equilibrium state, 238U approximately 230Th greater than 210Pb greater than 226Ra and 238U greater than 230Th greater than 210Pb greater than 226Ra. Thorium contents were found to be, in general, low and appreciable disequilibrium of the thorium series nuclides was not observed except one sample. Potassium contents were also very low (less than 0.3% K2O) except for complex fertilizers. Based on the present data, discussions were made for the radiation exposure due to phosphate fertilizers.

Radiometric dating by alpha spectrometry on uranium series nuclides

NARCIS (Netherlands)

Wijk, Albert van der

1987-01-01

De Engelse titel van dit proegschrift \\"Radiometric Dating by Alpha Spectometry on Uranium Series Nuclides\\" kan in het Nederlands wellicht het best worden weergegeven door \\"ouderdomsdbepalingen door stralingsmeting aan kernen uit de uraniumreeks met behulp van alfaspectometrie\\". In dit laatste

High resolution analysis of uranium and thorium concentration as well as U-series isotope distributions in a Neanderthal tooth from Payre (Ardèche, France) using laser ablation ICP-MS

Science.gov (United States)

Grün, Rainer; Aubert, Maxime; Joannes-Boyau, Renaud; Moncel, Marie-Hélène

2008-11-01

We have mapped U ( 238U) and Th ( 232Th) elemental concentrations as well as U-series isotope distributions in a Neanderthal tooth from the Middle Palaeolithic site of Payre using laser ablation ICP-MS. The U-concentrations in an enamel section varied between 1 and 1500 ppb. The U-concentration maps show that U-migration through the external enamel surface is minute, the bulk of the uranium having migrated internally via the dentine into the enamel. The uranium migration and uptake is critically dependent on the mineralogical structure of the enamel. Increased U-concentrations are observed along lineaments, some of which are associated with cracks, and others may be related to intra-prismatic zones or structural weaknesses reaching from the dentine into the enamel. The uranium concentrations in the dentine vary between about 25,000 and 45,000 ppb. Our systematic mapping of U-concentration and U-series isotopes provides insight into the time domain of U-accumulation. Most of the uranium was accumulated in an early stage of burial, with some much later overprints. None of the uranium concentration and U-series profiles across the root of the tooth complied with a single stage diffusion-adsorption (D-A) model that is used for quality control in U-series dating of bones and teeth. Nevertheless, in the domains that yielded the oldest apparent U-series age estimates, U-leaching could be excluded. This means that the oldest apparent U-series ages of around 200 ka represent a minimum age for this Neanderthal specimen. This is in good agreement with independent age assessments (200-230 ka) for the archaeological layer, in which it was found. The Th elemental concentrations in the dental tissues were generally low (between about 1 and 20 ppb), and show little relationship with the nature of the tissue.

Uranium in fossil bones

International Nuclear Information System (INIS)

Koul, S.L.

1978-01-01

An attempt has been made to determine the uranium content and thus the age of certain fossil bones Haritalyangarh (Himachal Pradesh), India. The results indicate that bones rich in apatite are also rich in uranium, and that the radioactivity is due to radionuclides in the uranium series. The larger animals apparently have a higher concentration of uranium than the small. The dating of a fossil jaw (elephant) places it in the Pleistocene. (Auth.)

Uranium and thorium series disequilibrium in quaternary carbonate deposits from the Serra da Bodoquena and Pantanal do Miranda, Mato Grosso do Sul State, central Brazil

International Nuclear Information System (INIS)

Ribeiro, Fernando Brenha; Roque, Arnaldo; Boggiani, Paulo Cesar; Flexor, J.-M.

2001-01-01

Activities of gamma-ray emitting members of the uranium ( 238 U) and thorium ( 232 Th) series were measured in a quaternary limestone deposit that outcrops in the southeastern Pantanal Matogrossense Basin and in quaternary tufas deposited at the drainage of the Serra da Bodoquena. It is a first step in a study of the mobilization of uranium and thorium series and its relation to surface hydrology, in a region where carbonate deposits are being continuously dissolved and reprecipitated. The obtained results show that all these deposits are characterized by very low concentrations of uranium and thorium. The 238 U/ 226 Ra and 228 Th/ 228 Ra activity ratios are significantly different than 1.0, indicating that both series are in radioactive disequilibrium. Although the Serra da Bodoquena deposits seem to be very recent, their very fine granulation and high porosity suggest that they behave as open systems for geochemical exchanges of uranium and thorium series members. The Pantanal do Miranda limestone has a radiocarbon age of 3900 yr BP. Since the thorium series is in disequilibrium it is also concluded that this deposit behaves as an open system for geochemical exchanges

Research on geochronology and uranium source of sandstone-hosted uranium ore-formation in major uranium-productive basins, Northern-China

International Nuclear Information System (INIS)

Xia Yuliang; Liu Hanbin; Lin Jinrong; Fan Guang; Hou Yanxian

2004-12-01

A method is developed for correcting uranium content in uranium ore samples by considering the U-Ra equilibrium coefficient, then a U-Pb isochron is drawn up. By performing the above correction ore-formation ages of sandstone-hosted uranium mineralization which may be more realistic have been obtained. The comparative research on U-Pb isotopic ages of detritic zircon in ore-hosting sandstone and zircon in intermediate-acid igneous rocks in corresponding provenance area indicates that the ore-hosting sandstone is originated from the erosion of intermediate-acid igneous rocks and the latters are the material basis for the formation of the uranium-rich sandstone beds. On the basis of the study on U-Pb isotopic system evolution of the provenance rocks and sandstones from ore-hosting series, it is verified that the uranium sources of the sandstone-hosted uranium deposit are: the intermediate-acid igneous rocks with high content of mobile uranium, and the sandstone bodies pre-concentrated uranium. (authors)

Geochemical behaviour of natural uranium-series nuclides in geological formation

International Nuclear Information System (INIS)

Yamakawa, Minoru

1991-01-01

Recent research and investigation show that the Tono uranium deposit and its natural uranium-series nuclides have been preserved, without any significant changes like re-migration or reconcentration, throughout geological events such as upheaval-submergence, marine transgression-regression, and faulting which can readily change geological, hydrogeological, and geochemical conditions. This situation might have come about as a result of being kept in a geometrical closure system, with reducing and milk alkalic geochemical conditions, from the hydrogeological and geochemical point of view. (author)

URANIUM-SERIES CONSTRAINTS ON RADIONUCLIDE TRANSPORT AND GROUNDWATER FLOW AT NOPAL I URANIUM DEPOSIT, SIERRA PENA BLANCA, MEXICO

Energy Technology Data Exchange (ETDEWEB)

S. J. Goldstein, S. Luo, T. L. Ku, and M. T. Murrell

2006-04-01

Uranium-series data for groundwater samples from the vicinity of the Nopal I uranium ore deposit are used to place constraints on radionuclide transport and hydrologic processes at this site, and also, by analogy, at Yucca Mountain. Decreasing uranium concentrations for wells drilled in 2003 suggest that groundwater flow rates are low (< 10 m/yr). Field tests, well productivity, and uranium isotopic constraints also suggest that groundwater flow and mixing is limited at this site. The uranium isotopic systematics for water collected in the mine adit are consistent with longer rock-water interaction times and higher uranium dissolution rates at the front of the adit where the deposit is located. Short-lived nuclide data for groundwater wells are used to calculate retardation factors that are on the order of 1,000 for radium and 10,000 to 10,000,000 for lead and polonium. Radium has enhanced mobility in adit water and fractures near the deposit.

URANIUM-SERIES CONSTRAINTS ON RADIONUCLIDE TRANSPORT AND GROUNDWATER FLOW AT NOPAL I URANIUM DEPOSIT, SIERRA PENA BLANCA, MEXICO

International Nuclear Information System (INIS)

S. J. Goldstein, S. Luo, T. L. Ku, and M. T. Murrell

2006-01-01

Uranium-series data for groundwater samples from the vicinity of the Nopal I uranium ore deposit are used to place constraints on radionuclide transport and hydrologic processes at this site, and also, by analogy, at Yucca Mountain. Decreasing uranium concentrations for wells drilled in 2003 suggest that groundwater flow rates are low (< 10 m/yr). Field tests, well productivity, and uranium isotopic constraints also suggest that groundwater flow and mixing is limited at this site. The uranium isotopic systematics for water collected in the mine adit are consistent with longer rock-water interaction times and higher uranium dissolution rates at the front of the adit where the deposit is located. Short-lived nuclide data for groundwater wells are used to calculate retardation factors that are on the order of 1,000 for radium and 10,000 to 10,000,000 for lead and polonium. Radium has enhanced mobility in adit water and fractures near the deposit

Pleistocene apparent ages by U-Pb isotope and U-series methods for uranium ore in Dakota Sandstone near Gallup, New Mexico

International Nuclear Information System (INIS)

Ludwig, K.R.; Szabo, B.J.; Granger, H.C.

1977-01-01

Radiometric dates of a high-grade uranium ore from the Hogback No. 4 mine in Dakota Sandstone near Gallup, N. Mex., indicate a late Pleistocene age of mineralization. The 206 Pb/ 238 U and 207 Pb/ 235 U apparent ages of about 70,000 y and 100,000 y, respectively, are discordant, but are in broad agreement with the discordant 230 Th/ 238 U and 230 Pa/ 235 U apparent ages of 130,000 y and 78,000 y, respectively. Although it is not clear how the analyzed sample relates to the main period of mineralization at this mine, these dates are consistent with previous age limits suggested for Dakota Sandstone uranium ores

Basis for the ICRP's age-specific biokinetic model for uranium

International Nuclear Information System (INIS)

Leggett, R.W.

1994-01-01

In an effort motivated largely by the Chernobyl nuclear accident, the International Commission on Radiological Protection (ICRP) is developing age-specific biokinetic models and dose coefficients for environmentally important radionuclides. This paper describes the ICRP's age-specific biokinetic model for uranium. The model is constructed within a physiologically based framework originally developed for application to the alkaline earth elements but sufficiently general to apply to the larger class of bone-volume-seeking elements. Transfer rates for a reference adult are based mainly on: (1) measurements of uranium in blood and excreta of several human subjects who were intravenously injected with uranium; (2) postmortem measurements of uranium in tissues of some of those subjects; (3) postmortem measurements of uranium in tissues of occupationally and non-occupationally exposed subjects; (4) data on baboons, dogs, and smaller laboratory animals exposed to uranium for experimental purposes; and (5) consideration of the physiological processes thought to control retention and translocation of uranium in the body. Transfer rates for the adult are extended to children by application of a set of generic assumptions applied by the ICRP to calcium-like elements. These assumptions were derived mainly from observations of the age-specific biokinetics of the alkaline earth elements and lead in humans and laboratory animals but are consistent with available age-specific biokinetic data on uranium. 82 refs., 17 figs., 8 tabs

Soiled-based uranium disequilibrium and mixed uranium-thorium series radionuclide reference materials

International Nuclear Information System (INIS)

Donivan, S.; Chessmore, R.

1988-12-01

The US Department of Energy (DOE) Office of Remedial Action and Waste Technology has assigned the Technical Measurements Center (TMC), located at the DOE Grand Junction Colorado, Projects Office and operated by UNC Geotech (UNC), the task of supporting ongoing remedial action programs by providing both technical guidance and assistance in making the various measurements required in all phases of remedial action work. Pursuant to this task, the Technical Measurements Center prepared two sets of radionuclide reference materials for use by remedial action contractors and cognizant federal and state agencies. A total of six reference materials, two sets comprising three reference materials each, were prepared with varying concentrations of radionuclides using mill tailings materials, ores, and a river-bottom soil diluent. One set (disequilibrium set) contains varying amounts of uranium with nominal amounts of radium-226. The other set (mixed-nuclide set) contains varying amounts of uranium-238 and thorium-232 decay series nuclides. 14 refs., 10 tabs

Discussion on uranium ore-formation age in Xiazhuang ore-field, northern Guangdong

International Nuclear Information System (INIS)

Wu Lieqin; Tan Zhengzhong; Liu Ruzhou; Huang Guolong

2003-01-01

There exist two genetic types of granite-type uranium deposits, i.e. the early-stage one, and the late-stage one. The early-stage uranium deposits are characterized by ore-formation ages of 122-138 Ma, and are high-grade uranium deposits of postmagmatic hydrothermal origin. The late-stage uranium deposits have ore-formation ages of 54-96 Ma. They mostly are low-grade uranium deposits, and of hydrothermal-regeneration origin with the uranium source derived from the mobilization of consolidated rocks. The early-stage uranium deposits should be the main target of further prospecting for high-grade uranium deposits in the region

Uranium-series dated authigenic carbonates and Acheulian sites in southern Egypt

International Nuclear Information System (INIS)

Szabo, B.J.; McHugh, W.P.; Schaber, G.G.; Breed, C.S.; Haynes, C.V.

1989-01-01

Field investigations in southern Egypt have yielded Acheulian artifacts in situ in authigenic carbonate deposits (CaCO 3 -cemented alluvium) along the edges of now-aggraded paleovalleys (Wadi Arid and Wadi Safsaf). Uranium-series dating of 25 carbonate samples from various localities as far apart as 70 kilometers indicates that widespread carbonate deposition occurred about 45, 141 and 212 ka (thousand years ago). Most of the carbonate appears to have been precipitated from groundwater, which suggests that these three episodes of deposition may be related to late Pleistocene humid climates that facilitated human settlement in this now hyperarid region. Carbonate cements from sediments containing Acheulian artifacts provide a minimum age of 212 ka for early occupation of the paleovalleys. 16 refs., 3 figs., 2 tabs

The feasibility and prospect of uranium-gas in black rock series of joint exploration and development

International Nuclear Information System (INIS)

Xu Guochang; Zhang Dehua; Zhang Hongjian

2014-01-01

By the analysis and contrast of existing form of gas-uranium, correlation between gas-uranium and organic matter, distribution characteristics and control factors of mineralization (bosom) in the sedimentary formation of shale gas and black uranium bearing rock series, the authors come to the conclusion that: in the carbonate-siliceous-pelitic of black rock series the uranium and gas (oil) is essentially equipped coenosarc of the same homology, syngenetic, reservoir. They are ore source beds of carbonate-siliceous-pelitic rock uranium deposit, and also the hydrocarbon source beds in which the shale gas form. In black shales, uranium largely exist in the form of the ion adsorption (acetyl ion/uranyl ion). Under fracturing conditions, we can realize desorption mode of chemical solvents of adding acid or alkali, and extract uranium by concentrating liquid (the same as in-situ mimng technology). Therefore, the fracturing technology (clear water fracturing techniques, repeat fracturing techniques, synchronization fracturing techniques, multistage fracturing techniques, network fracturing techniques and so on) of shale gas exploitation lay a foundation for black shale uranium-gas joint development. The mature and corollary use of fracturing techniques and in-situ mining technology of low grade uranium will undoubtedly further increase the industrial resource extent of uranium and gas, improve guaranteeing degree of resource, reform of promote energy production structure and provide a large number of economical and effective clean energy. (authors)

Uranium-series growth history of a Quaternary phosphatic crust from the Peruvian continental margin

International Nuclear Information System (INIS)

Kim, Kee Hyun; Burnett, W.C.

1986-01-01

A 20-mm-thick oriented phosphatic crust recovered together with its overlying (14 cm) and underlying (4 cm) associated sediment from the Peruvian sea floor has been analyzed in detail for uranium-series radionuclides in an attempt to determine its rate and direction of growth. Growth curves based upon 226 Ra and 230 Th ages show that this crust grew upward toward the sediment-water interface. Calculated growth rates in the range of 12-13 mm ka -1 are slightly higher but comparable to values previously reported. Crystallographical analyses of this phosphatic crust show a trend of decreasing unit-cell dimension a with sample age. The upward growth of a buried crust toward the sediment-water interface is consistent with results from recent pore-water studies of fluoride and phosphate in Peru shelf sediments. (orig.)

Uranium Age Determination by Measuring the 230Th / 234U Ratio

International Nuclear Information System (INIS)

LAMONT, STEPHEN P.

2004-01-01

A radiochemical isotope dilution mass spectrometry method has been developed to determine the age of uranium materials. The amount of 230Th activity, the first progeny of 234U, that had grown into a small uranium metal sample was used to determine the elapsed time since the material was last radiochemically purified. To preserve the sample, only a small amount of oxidized uranium was removed from the surface of the sample and dissolved. Aliquots of the dissolved sample were spiked with 233U tracer and radiochemically purified by anion-exchange chromatography. The 234U isotopic concentration was then determined by thermal ionization mass spectrometry. Additional aliquots of the sample were spiked with 229Th tracer, and the thorium was purified using two sequential anion-exchange chromatography separations. The isotopic concentrations of 230Th and 232Th were determined by TIMS. The lack of any 232Th confirmed the assumption that all thorium was removed from the uranium sample at the time of purification. The 230Th and 234U mass concentrations were converted to activities and the 230Th/234U ratio for the sample was calculated. The experimental 230Th/234U ratio showed the uranium in this sample was radiochemically purified in about 1945. Isotope dilution thermal ionization mass spectrometry has sufficient sensitivity to determine the age of 100 samples of uranium. This method could certainly be employed as a nuclear forensic method to determine the age of small quantities of uranium metal or salts. Accurate determination of the ultra-trace 230Th radiochemically separated from the uranium is possible due to the use of 229Th as an isotope dilution tracer. The precision in the experimental age of the uranium could be improved by making additional replicate measurements of the 230Th/234U isotopic ratio or using a larger initial sample

Aspects of uranium/thorium series disequilibrium applications to radionuclide migration studies

International Nuclear Information System (INIS)

Ivanovich, M.

1989-11-01

The aim of this paper is to consider the contribution which the uranium/thorium series disequilibrium concept can make to understanding the retardation and transport of radionuclides in the far-field of a radioactive waste repository. In principle, naturally occurring isotopes of uranium, thorium and radium can be regarded as geochemical analogues of the divalent radionuclides and multivalent actinides expected to be present in the radioactive waste inventory. The study of their retardation and/or transport in real rock/water systems which have taken place over geological timescales, can make an important contribution to establishing a rational basis for long-term predictive modelling of radionuclide transport required for safety assessments. (author)

Rubidium-strontium and uranium-lead isotopic age studies

International Nuclear Information System (INIS)

Loveridge, W.D.

1980-01-01

Rubidium-strontium whole rock isochron ages and initial 87 Sr/ 86 Sr ratios and uranium-lead ages on zircon from suites of samples selected from localities across Canada are presented. Descriptions of the geological probelms and interpretations of the measured ages are included. Laboratory age determination methods and techniques are described or referenced. (auth)

Unconventional uranium resources in China

International Nuclear Information System (INIS)

Qi Fucheng; Zhang Zilong; Li Zhixing; Wang Zhiming; He Zhongbo; Wang Wenquan

2011-01-01

Unconventional uranium resources in China mainly include black-rock series, peat, salt lake and evaporitic rocks. Among them, uraniferous black-rock series, uraniferous phosphorite and uranium-polymetallic phosphorite connected with black-rock series are important types for the sustainable support of uranium resources in China. Down-faulting and epocontinental rift in continental margin are the most important and beneficial ore-forming environment for unconventional uranium resources of black-rock series in China and produced a series of geochemistry combinations, such as, U-Cd, U-V-Mo, U-V-Re, U-V-Ni-Mo and U-V-Ni-Mo-Re-Tl. Unconventional uranium resources of black-rock series in China is related to uranium-rich marine black-rock series which are made up of hydrothermal sedimentary siliceous rocks, siliceous phospheorite and carbonaceous-siliceous-pelitic rock and settled in the continental margin down-faulting and epicontinental rift accompanied by submarine backwash and marine volcano eruption. Hydrothermal sedimentation or exhalation sedimentary is the mechanism to form unconventional uranium resources in black-rock series or large scale uranium-polymetallic mineralization in China. (authors)

Analysis of the gamma spectra of the uranium, actinium, and thorium decay series

International Nuclear Information System (INIS)

Momeni, M.H.

1981-09-01

This report describes the identification of radionuclides in the uranium, actinium, and thorium series by analysis of gamma spectra in the energy range of 40 to 1400 keV. Energies and absolute efficiencies for each gamma line were measured by means of a high-resolution germanium detector and compared with those in the literature. A gamma spectroscopy method, which utilizes an on-line computer for deconvolution of spectra, search and identification of each line, and estimation of activity for each radionuclide, was used to analyze soil and uranium tailings, and ore

Uranium series geochemistry in aquifers: quantification of transport mechanisms of uranium and daughter products: the chalk aquifer (Champagne, France)

International Nuclear Information System (INIS)

Hubert, A.

2005-09-01

With the increase of contaminant flux of radionuclides in surface environment (soil, river, aquifer...), there is a need to understand and model the processes that control the distribution of uranium and its daughter products during transport within aquifers. We have used U-series disequilibria as an analogue for the transport of uranium and its daughter products in aquifer to understand such mechanisms. The measurements of uranium ( 234 U et 238 U), thorium ( 230 Th et 232 Th), 226 Ra and 222 Rn isotopes in the solid and liquid phases of the chalk aquifer in Champagne (East of France) allows us to understand the processes responsible for fractionation within the uranium decay chain. Fractionations are induced by physical and chemical properties of the elements (leaching, adsorption) but also by radioactive properties (recoil effect during α-decay). For the first time a comprehensive sampling of the solid phase has been performed, allowing quantifying mechanisms responsible for the long term evolution of the aquifer. A non steady state 1D model has been developed which takes into account leaching, adsorption processes as well as radioactive filiation and α-recoil effect. Retardation coefficients have been calculated for uranium, thorium and radium. The aquifer is characterised by a double porosity, and the contribution of fracture and matrix porosity on the water/rock interaction processes has been estimated. (author)

New age constraints on the Middle Stone Age occupations of Kharga Oasis, Western Desert, Egypt.

Science.gov (United States)

Smith, Jennifer R; Hawkins, Alicia L; Asmerom, Yemane; Polyak, Victor; Giegengack, Robert

2007-06-01

Spring-deposited carbonate rocks, or tufas, exposed along the flanks of the Libyan Plateau near Kharga Oasis, Western Desert, Egypt, can provide a directly datable stratigraphic context for Middle Stone Age/Middle Paleolithic (MSA/MP) archaeological material, if such material can be found in situ within tufa strata. Two such localities (Mata'na Site G and Bulaq Wadi 3 Locus 1) described by Caton-Thompson were revisited and sampled for uranium-series analysis. At Mata'na Site G (KH/MT-02), Middle Stone Age ("Upper Levalloisian") material is underlain by tufa with a uranium-series age of 127.9+/-1.3 ka, and overlain by tufa with an age of 103+/-14 ka. At Bulaq Wadi 3 Locus 1, a uranium-series age of 114.4+/-4.2 ka on tufa capping a small collection of Middle Stone Age artifacts also provides a minimum age constraint on that material. Tufa underlying an MSA workshop (KH/MD-10) indicates that this assemblage, characterized by use of several Levallois reduction methods, was deposited after approximately 124 ka. Furthermore, uranium-series ages averaging approximately 133 ka on a Wadi Midauwara tufa (WME-10) without associated archaeological material suggest that one period of spring flow in the region began during the Marine Isotope Stage 6/5e transition, prior to the warmest portion of the last interglacial period. The dated archaeological material suggests that the distinction that has been identified between Nubian and non-Nubian complexes in the Nile Valley may hold for the Western Desert, although local complexity has yet to be fully described.

Evaluation of mass transport property using natural uranium-series and thorium-series nuclides in the Toki Granite

International Nuclear Information System (INIS)

Hama, Katsuhiro

2016-07-01

The Mizunami Underground Research Laboratory (MIU) project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant disposal technologies through investigations of the deep geological environment within the host crystalline rock at Mizunami City in Gifu Prefecture, central Japan. The project proceeds in three overlapping phases, 'Phase I: Surface-based investigation Phase', 'Phase II: Construction Phase' and 'Phase III: Operation Phase'. As a part of the Phase III investigation, the mass transport property has been evaluated by using natural uranium-series and thorium-series nuclides in the Toki Granite. In this report, the compilation of existing data and preliminary evaluation was carried out. (author)

Uranium series disequilibrium: application to studies of the groundwater regime of the Harwell region

International Nuclear Information System (INIS)

Ivanovich, M.; Alexander, J.

1985-03-01

Regional groundwater systems incorporating argillaceous formations beneath the Harwell site have been studied as part of a national research programme of investigation into the feasibility of disposal of low and intermediate radioactive wastes into argillaceous rocks. The principal aim of the programme is to establish the groundwater flow patterns using hydrogeological and geochemical methods in association with isotope contents and uranium series disequilibrium and thus provide an independent approach to the study of effective permeabilities of clay lithologies in a sedimentary sequence. Thirty four groundwater samples derived from the high permeability formations in the Harwell region have been analysed for uranium and thorium content and 234 U/ 238 U, 230 Th/ 234 U and 230 Th/ 232 Th activity ratios. The uranium isotopic signatures have been interpreted in terms of the regional groundwater circulation and mixing patterns. The most significant zones of groundwater mixing determined from uranium isotopic data are situated just beneath the edge of the confined strata. These zones coincide with the locations of hydraulic lows in the Great Oolite and the Corallian formations towards which the regional groundwaters move. It is concluded that the uranium isotopic signatures can be used to identify water masses and to evaluate mixing of groundwaters in a sedimentary sequence on a regional scale. (author)

Radiochronological Age of a Uranium Metal Sample from an Abandoned Facility

Energy Technology Data Exchange (ETDEWEB)

Meyers, L A; Williams, R W; Glover, S E; LaMont, S P; Stalcup, A M; Spitz, H B

2012-03-16

A piece of scrap uranium metal bar buried in the dirt floor of an old, abandoned metal rolling mill was analyzed using multi-collector inductively coupled plasma mass spectroscopy (MC-ICP-MS). The mill rolled uranium rods in the 1940s and 1950s. Samples of the contaminated dirt in which the bar was buried were also analyzed. The isotopic composition of uranium in the bar and dirt samples were both the same as natural uranium, though a few samples of dirt also contained recycled uranium; likely a result of contamination with other material rolled at the mill. The time elapsed since the uranium metal bar was last purified can be determined by the in-growth of the isotope {sup 230}Th from the decay of {sup 234}U, assuming that only uranium isotopes were present in the bar after purification. The age of the metal bar was determined to be 61 years at the time of this analysis and corresponds to a purification date of July 1950 {+-} 1.5 years.

Radiochronological age of a uranium metal sample from an abandoned facility

International Nuclear Information System (INIS)

Meyers, L.A.; Stalcup, A.M.; Glover, S.E.; Spitz, H.B.

2013-01-01

A piece of scrap uranium metal bar buried in the dirt floor of an old, abandoned metal rolling mill was analyzed using multi-collector inductively coupled plasma mass spectroscopy (MC-ICP-MS). The mill rolled uranium rods in the 1940 and 1950s. Samples of the contaminated dirt in which the bar was buried were also analyzed. The isotopic composition of uranium in the bar and dirt samples were both the same as natural uranium, though a few samples of dirt also contained recycled uranium; likely a result of contamination with other material rolled at the mill. The time elapsed since the uranium metal bar was last purified can be determined by the in-growth of the isotope 230 Th from the decay of 234 U, assuming that only uranium isotopes were present in the bar after purification. The age of the metal bar was determined to be 61 years at the time of this analysis and corresponds to a purification date of July 1950 ± 1.5 years. (author)

Radiochronological Age of a Uranium Metal Sample from an Abandoned Facility

International Nuclear Information System (INIS)

Meyers, L.A.; Williams, R.W.; Glover, S.E.; LaMont, S.P.; Stalcup, A.M.; Spitz, H.B.

2012-01-01

A piece of scrap uranium metal bar buried in the dirt floor of an old, abandoned metal rolling mill was analyzed using multi-collector inductively coupled plasma mass spectroscopy (MC-ICP-MS). The mill rolled uranium rods in the 1940s and 1950s. Samples of the contaminated dirt in which the bar was buried were also analyzed. The isotopic composition of uranium in the bar and dirt samples were both the same as natural uranium, though a few samples of dirt also contained recycled uranium; likely a result of contamination with other material rolled at the mill. The time elapsed since the uranium metal bar was last purified can be determined by the in-growth of the isotope 230 Th from the decay of 234 U, assuming that only uranium isotopes were present in the bar after purification. The age of the metal bar was determined to be 61 years at the time of this analysis and corresponds to a purification date of July 1950 ± 1.5 years.

Separation of uranium in bone rest for their dating

International Nuclear Information System (INIS)

Garcia R, G.; Ordonez R, E.; Tenorio, D.; Cordoba, L.

2001-01-01

The uranium (U) and thorium (Th) recovery, as fundamental part of the 'uranium serie' technique is an alternative method for dating of bone rests in Mexico. That so is how it has been possible its application for dating geological material and in this research it has been determined the age of some mammoth samples from the basin of Mexico valley. (Author)

Fission track ages and uranium concentration of apatites of different rocks of South India

International Nuclear Information System (INIS)

Nand Lal; Nagpaul, K.K.; Nagpal, M.K.

1975-01-01

The uranium concentration and ages of apatite grains of various rocks of South India have been measured by fission track technique. The ages range from 100 m.y. to 730 m.y. whereas uranium concentrations vary from 0.5 to 23.8 atom/million atoms of the apatite mineral. The ages agree well with the Deccan volcanic and Ocean Cycle activities. (author)

Uranium age determination - Separation and analysis of 230Th and 231Pa

International Nuclear Information System (INIS)

Morgenstern, A.; Apostolidis, C.; Mayer, K.; Wallenius, M.

2002-01-01

Full text: In recent years several incidents involving illicit trafficking and smuggling of nuclear material, radioactive sources and radioactively contaminated materials have raised growing public concern about criminal acts involving nuclear materials. Consequently, research efforts in nuclear forensic science have been intensified in order to develop and improve methods for the identification of the nature and origin of seized materials. Information obtained from the analysis of unknown nuclear materials is of key importance in order to aide authorities that are in charge of developing fast and appropriate response action. For the identification of nuclear materials various sample characteristics are of relevance, including isotopic composition, the content of chemical impurities, material properties and the date of production. Information on the production date, respectively the 'age' of nuclear materials, will also be of key importance in other fields of nuclear science, i.e. for the verification of a Fissile Materials Cut-Off Treaty (FMCT) in order to distinguish freshly produced materials from 'old' excess weapons materials. The age of nuclear materials may also be of relevance under a strengthened safeguards regime to reveal clandestine production of weapons usable materials, i.e. the separation of plutonium or production of highly enriched uranium (HEU). The age dating of plutonium samples has been described in detail for bulk samples as well as for particles. In this work we focused on the age determination of uranium materials of different uranium enrichment. The radioactive decay of the uranium isotopes provides a chronometer that is inherent to the material, in particular the mother/daughter pairs 234 U/ 230 Th and 235 U/ 231 Pa can be advantageously used. Due to the relatively long half-lives of 234 U (2.46·10 5 years) and 235 U (7.04·10 8 years) only minute amounts of daughter nuclides are growing in, therefore both separation of Th and Pa from

Study of the subduction-related magmatism and of the continental erosion, by uranium-series: constraints on the processes and the timescale

International Nuclear Information System (INIS)

Dosseto, A.

2003-01-01

(The first part of this research thesis in geochemistry proposes an overview of knowledge and a description of the contribution of uranium-series to the magmatism in subduction zones. The second part addresses the continental erosion, and more particularly the alteration regimes and the dynamics of transfer of sediments constrained by uranium-series. Already published articles complete this report: U-Th-Pa-Ra study of the Kamchatka arc: new constraints on genesis of arc basalts; Dehydration and partial melting in subduction zones: constraints from U-series disequilibria; Timescale and conditions of chemical weathering under tropical climate: study of the Amazon basin with U-series; Timescale and conditions of chemical weathering in the Bolivian Andes and their fore-land basin

National low-level waste management program radionuclide report series, Volume 15: Uranium-238

International Nuclear Information System (INIS)

Adams, J.P.

1995-09-01

This report, Volume 15 of the National Low-Level Waste Management Program Radionuclide Report Series, discusses the radiological and chemical characteristics of uranium-238 ( 238 U). The purpose of the National Low-Level Waste Management Program Radionuclide Report Series is to provide information to state representatives and developers of low-level radioactive waste disposal facilities about the radiological, chemical, and physical characteristics of selected radionuclides and their behavior in the waste disposal facility environment. This report also includes discussions about waste types and forms in which 238 U can be found, and 238 U behavior in the environment and in the human body

LA-ICPMS zircon U-Pb age of Maofeng pluton of uranium deposit No.337 and its significance

International Nuclear Information System (INIS)

Zhang Zhanshi; Hua Renmin; Yao Junmin; Gu Shengyan; Deng Ping; Wu Lieqin

2007-01-01

Maofeng pluton is the most important uranium-host granite in Xiazhuang uranium orefield. The accurate granite formation age and its evolution history is crucial for understanding the mineralization in this district. LA-ICPMS zircon dating was applied in this paper and found the formation age of Maofeng pluton is 238.2 ± 2.3 Ma which suggests that Maofeng pluton was produced in the Indosinian magmatic event. Uranium mineralization age of No.337 deposit is commonly recognized to be 138 Ma. Therefore No.337 uranium deposit was not the typical magma hydrothermal deposit due to the long time gap between the pluton formation and the uranium mineralization. (authors)

Age specific interactions between smoking and radon among United States uranium miners

International Nuclear Information System (INIS)

Steenland, K.

1994-01-01

United States uranium miners who smoked have death rates from lung cancer that are intermediate between the rates predicted by the additive and multiplicative models (on a ratio scale) across all age groups. Age specific patterns of interaction have not been thoroughly examined, and most analyses have been internal ones in which there was no truly non-exposed group. Here age specific death rates of lung cancer among ever smoking uranium miners have been examined for conformity with the additive and multiplicative models. The multiplicative model fits well for the youngest and oldest categories, but poorly for the middle age ranges. In the middle age range, predicted rates under the multiplicative model were quite high, surpassing the corresponding United States death rates for all causes combined. (Author)

Uranium-series disequilibrium studies in phosphorite nodules from the west coast of South America

International Nuclear Information System (INIS)

Burnett, W.C.; Veeh, H.H.

1977-01-01

Sedimentary phosphorites occurring on the sea floor off Peru and Chile have been analyzed for U and Th isotopes, to establish their ages and hence obtain clues for their mode of formation. Fission-track distribution studies indicate that the U is primarily associated with the apatite fraction. Uranium-series disequilibrium methods, therefore, should be applicable, if the U incorporation is syngenetic with the apatite. The fractionation of U isotopes between oxidation states in the relatively young phosphorites from South America is low compared to that in older deposits. This supports the contention of Kolodny et al., (Geochim.Cosmochim.Acta;34:3 (1970)) that the major mechanism of 234 U/ 238 U fractionation is displacement of 234 U atoms into sites where they are more 'oxidizable' than the 238 U parent. Age estimates based on 234 U(IV) and 230 Th contents are internally consistent and range from late Pleistocene to Recent. The results indicate that marine phosphorites are currently forming in this area of intense oceanic upwelling. The age pattern during the last 150,000 yr suggests a correlation with eustatic high sea level stands and implies that conditions were more favourable for apatite genesis in this area during interglacials rather than during glacial times. (author)

Uranium series disequilibrium dating of coral and shell fragments dredged around islands and seamounts during the 1986 HMNZS Tui cruises

International Nuclear Information System (INIS)

McCabe, W.J.; Ditchburn, R.G.; Glasby, G.P.

1996-01-01

Nine coral and two shell samples dredged from the flanks of various islands and seamounts in the subtropical SW Pacific were processed through the uranium series analysis system and ages calculated. Although there is a tendency for sample ages to increase with water depth, the presence of corals less than 1000 years old at water depths of 400 to almost 1100 m indicates the influence of recent slumping rather than crustal warping or eustatic changes as reasons for their present position. This phenomenon is related to mass wasting of material down slope. It is possible that samples collected systematically down the slopes of these islands would enable the frequency and times of slumping to be determined. (author). 7 refs., 2 figs., 7 tabs

Gas Generation from K East Basin Sludges and Irradiated Metallic Uranium Fuel Particles Series III Testing

International Nuclear Information System (INIS)

Schmidt, Andrew J.; Delegard, Calvin H.; Bryan, Samuel A.; Elmore, Monte R.; Sell, Rachel L.; Silvers, Kurt L.; Gano, Susan R.; Thornton, Brenda M.

2003-01-01

The path forward for managing of Hanford K Basin sludge calls for it to be packaged, shipped, and stored at T Plant until final processing at a future date. An important consideration for the design and cost of retrieval, transportation, and storage systems is the potential for heat and gas generation through oxidation reactions between uranium metal and water. This report, the third in a series (Series III), describes work performed at the Pacific Northwest National Laboratory (PNNL) to assess corrosion and gas generation from irradiated metallic uranium particles (fuel particles) with and without K Basin sludge addition. The testing described in this report consisted of 12 tests. In 10 of the tests, 4.3 to 26.4 g of fuel particles of selected size distribution were placed into 60- or 800-ml reaction vessels with 0 to 100 g settled sludge. In another test, a single 3.72-g fuel fragment (i.e., 7150-mm particle) was placed in a 60 ml reaction vessel with no added sludge. The twelfth test contained only sludge. The fuel particles were prepared by crushing archived coupons (samples) from an irradiated metallic uranium fuel element. After loading the sludge materials (whether fuel particles, mixtures of fuel particles and sludge, or sludge-only) into reaction vessels, the solids were covered with an excess of K Basin water, the vessels closed and connected to a gas measurement manifold, and the vessels back-flushed with inert neon cover gas. The vessels were then heated to a constant temperature. The gas pressures and temperatures were monitored continuously from the times the vessels were purged. Gas samples were collected at various times during the tests, and the samples analyzed by mass spectrometry. Data on the reaction rates of uranium metal fuel particles with water as a function of temperature and particle size were generated. The data were compared with published studies on metallic uranium corrosion kinetics. The effects of an intimate overlying sludge layer

Budgets and behaviors of uranium and thorium series isotopes in the Santa Monica Basin off the California Coast

Energy Technology Data Exchange (ETDEWEB)

Yu, Lei.

1991-12-16

Samples from three time-series sediment traps deployed in the Santa Monica Basin off the California coast were analyzed to study the flux and scavenging of uranium and thorium series isotopes. Variations of uranium and thorium series isotopes fluxes in the water column were obtained by integrating these time-series deployment results. Mass and radionuclide fluxes measured from bottom sediment traps compare favorably with fluxed determined from sediment core data. This agreement suggests that the near-bottom sediment traps are capable of collecting settling particles representative of the surface sediment. The phase distributions of {sup 234}Th in the water column were calculated by an inverse method using sediment trap data, which help to study the variations of {sup 234}Th scavenging in the water column. Scavenging and radioactive decay of {sup 234}Th are the two principal processes for balancing {sup 234}Th budget in the water column. The residence times of dissolved and particulate {sup 234}Th were determined by a {sup 234}Th scavenging model.

Budgets and behaviors of uranium and thorium series isotopes in the Santa Monica Basin off the California Coast

Energy Technology Data Exchange (ETDEWEB)

Yu, Lei [Oregon State Univ., Corvallis, OR (United States)

1991-12-16

Samples from three time-series sediment traps deployed in the Santa Monica Basin off the California coast were analyzed to study the flux and scavenging of uranium and thorium series isotopes. Variations of uranium and thorium series isotopes fluxes in the water column were obtained by integrating these time-series deployment results. Mass and radionuclide fluxes measured from bottom sediment traps compare favorably with fluxed determined from sediment core data. This agreement suggests that the near-bottom sediment traps are capable of collecting settling particles representative of the surface sediment. The phase distributions of ²³⁴Th in the water column were calculated by an inverse method using sediment trap data, which help to study the variations of ²³⁴Th scavenging in the water column. Scavenging and radioactive decay of ²³⁴Th are the two principal processes for balancing ²³⁴Th budget in the water column. The residence times of dissolved and particulate ²³⁴Th were determined by a ²³⁴Th scavenging model.

230Th-234U Model-Ages of Some Uranium Standard Reference Materials

International Nuclear Information System (INIS)

Williams, R.W.; Gaffney, A.M.; Kristo, M.J.; Hutcheon, I.D.

2009-01-01

The 'age' of a sample of uranium is an important aspect of a nuclear forensic investigation and of the attribution of the material to its source. To the extent that the sample obeys the standard rules of radiochronometry, then the production ages of even very recent material can be determined using the 230 Th- 234 U chronometer. These standard rules may be summarized as (a) the daughter/parent ratio at time=zero must be known, and (b) there has been no daughter/parent fractionation since production. For most samples of uranium, the 'ages' determined using this chronometer are semantically 'model-ages' because (a) some assumption of the initial 230 Th content in the sample is required and (b) closed-system behavior is assumed. The uranium standard reference materials originally prepared and distributed by the former US National Bureau of Standards and now distributed by New Brunswick Laboratory as certified reference materials (NBS SRM = NBL CRM) are good candidates for samples where both rules are met. The U isotopic standards have known purification and production dates, and closed-system behavior in the solid form (U 3 O 8 ) may be assumed with confidence. We present here 230 Th- 234 U model-ages for several of these standards, determined by isotope dilution mass spectrometry using a multicollector ICP-MS, and compare these ages with their known production history

Uptake of uranium and thorium series radionuclides by the waterlily, Nymphaea violacea

International Nuclear Information System (INIS)

Pettersson, H.B.L.

1993-01-01

The waterlily Nymphaea violacea is a major aquatic macrophyte in the waters of the Alligator Rivers Region, Northern Territory, Australia. It is also a traditional Aboriginal diet item, and is considered to be potentially one of the main contributors to the effective dose equivalent arising from consumption of so called bush food in the region. Because of the proximity of the Ranger Uranium Mine (RUM), the activity concentrations of the U and Th series radionuclides have been studied in water, sediment and waterlily during different seasons at five sites downstream of the mine site. The objectives of the study are: 1. To identify the major source of radionuclide uptake by the plant; i.e. water or sediment; 2. To assess the concentration factors/ratios needed for predicting the radiation exposure of the critical group resulting from any discharge of water to the aquatic environment from the Ranger uranium mine; 3. To estimate the natural radiation exposure of the public arising from consumption of waterlilies. (Author)

The structure environment, rock-magma system, mineral-forming series and pattern of volcanic mineral-forming of uranium deposit in southeast of China

International Nuclear Information System (INIS)

Yu Dagan

1992-01-01

The Volcanic uranium deposit of rock-magma belt-the Mid-Cz Volcano in the Southeast of China mainly formed around 120 ∼ 130 Ma and 90 ∼ 100 Ma Which is in harmony with the two rock magma activities of k within the region. The rock-magma system of this period formed around the turning period from pressure to tension in the continent margin of southeast China, which is mainly characterized by the appearance of A-type granite and alkaline, sub-alkaline rocks (trachyte, trachyandensite, trachybasalt, basic rock alkaline basalt). The uranium deposit is controlled by the base rift of dissection to the mantle, the volcanic basin is of the double characteristics of transversal rift valley basin (early period) ad tension rift valley basin (laster period). The leading role of the deep source is stressed in terms of internal-forming series of volcanic uranium deposits is considered to exist; and also in terms of internal-forming series of volcanic uranium deposits is considered to exist; and also in terms of mineral-forming patterns, the multi-pattern led by the deep-source is stressed, including the mineral-forming pattern of uranium deposit of continental thermos, repeated periphery mineral-forming pattern of uranium deposit and the mineral-forming pattern of uranium deposit of rising pole-like thermos. Ten suggestions are put forward to the next mineral-search according to the above thoughts

Uranium series geochemistry in aquifers: quantification of transport mechanisms of uranium and daughter products: the chalk aquifer (Champagne, France); Desequilibres des series de l'uranium dans les aquiferes: quantification des mecanismes de transport de l'uranium et de ses descendants: cas de l'aquifere de la craie (Champagne, France)

Energy Technology Data Exchange (ETDEWEB)

Hubert, A

2005-09-15

With the increase of contaminant flux of radionuclides in surface environment (soil, river, aquifer...), there is a need to understand and model the processes that control the distribution of uranium and its daughter products during transport within aquifers. We have used U-series disequilibria as an analogue for the transport of uranium and its daughter products in aquifer to understand such mechanisms. The measurements of uranium ({sup 234}U et {sup 238}U), thorium ({sup 230}Th et {sup 232}Th), {sup 226}Ra and {sup 222}Rn isotopes in the solid and liquid phases of the chalk aquifer in Champagne (East of France) allows us to understand the processes responsible for fractionation within the uranium decay chain. Fractionations are induced by physical and chemical properties of the elements (leaching, adsorption) but also by radioactive properties (recoil effect during {alpha}-decay). For the first time a comprehensive sampling of the solid phase has been performed, allowing quantifying mechanisms responsible for the long term evolution of the aquifer. A non steady state 1D model has been developed which takes into account leaching, adsorption processes as well as radioactive filiation and {alpha}-recoil effect. Retardation coefficients have been calculated for uranium, thorium and radium. The aquifer is characterised by a double porosity, and the contribution of fracture and matrix porosity on the water/rock interaction processes has been estimated. (author)

Possible uranium sources of Streltsovsky uranium ore field

International Nuclear Information System (INIS)

Zhang Lisheng

2005-01-01

The uranium deposit of the Late Jurassic Streltsovaky caldera in Transbaikalia of Russia is the largest uranium field associated with volcanics in the world, its uranium reserves are 280 000 t U, and it is the largest uranium resources in Russia. About one third of the caldera stratigraphic pile consists of strongly-altered rhyolites. Uranium resources of the Streltsovsky caldera are much larger than any other volcanic-related uranium districts in the world. Besides, the efficiency of hydrothermal alteration, uranium resources appear to result from the juxtaposition of two major uranium sources; highly fractionated peralkaline rhyolites of Jurassic age in the caldera, and U-rich subalkaline granites of Variscan age in the basement in which the major uranium-bearing accessory minerals were metamict at the time of the hydrothermal ore formation. (authors)

Age-dependent radiation dose due to intake of uranium through drinking water in India

International Nuclear Information System (INIS)

Sahoo, S.K.; Mohapatra, S.; Chakrabarty, A.; Sumesh, C.G.; Tripathi, R.M.; Puranik, V.D.

2009-01-01

In the present study, an attempt has been made to estimate the content of uranium in drinking water in various states of India by laser fluorimetry. Depending upon the rate of water intake for the different age groups, the associated radiation dose was calculated. The concentration of uranium varied between 0.1 ± 0.01 and 19.6 ± 1.8 ppb which is much lower than the drinking water guideline value of 60 ppb. The total radiation dose due to ingestion of uranium through drinking water for various age groups is found to vary from 0.14 μSv/y to 48 μSv/y. (author)

230Th-234U Model-Ages of Some Uranium Standard Reference Materials

Energy Technology Data Exchange (ETDEWEB)

Williams, R W; Gaffney, A M; Kristo, M J; Hutcheon, I D

2009-05-28

The 'age' of a sample of uranium is an important aspect of a nuclear forensic investigation and of the attribution of the material to its source. To the extent that the sample obeys the standard rules of radiochronometry, then the production ages of even very recent material can be determined using the {sup 230}Th-{sup 234}U chronometer. These standard rules may be summarized as (a) the daughter/parent ratio at time=zero must be known, and (b) there has been no daughter/parent fractionation since production. For most samples of uranium, the 'ages' determined using this chronometer are semantically 'model-ages' because (a) some assumption of the initial {sup 230}Th content in the sample is required and (b) closed-system behavior is assumed. The uranium standard reference materials originally prepared and distributed by the former US National Bureau of Standards and now distributed by New Brunswick Laboratory as certified reference materials (NBS SRM = NBL CRM) are good candidates for samples where both rules are met. The U isotopic standards have known purification and production dates, and closed-system behavior in the solid form (U{sub 3}O{sub 8}) may be assumed with confidence. We present here {sup 230}Th-{sup 234}U model-ages for several of these standards, determined by isotope dilution mass spectrometry using a multicollector ICP-MS, and compare these ages with their known production history.

Distribution of natural radionuclides of uranium and thorium series in the process of artesian water treatment for drinking consumption

International Nuclear Information System (INIS)

Grashchenko, S.M.; Gritchenko, Z.G.; Shishkunova, L.V.

1997-01-01

Distribution of natural radionuclides of uranium and thorium series during the treatment of artesian water for drinking consumption is studied using vacuum-emanation and gamma spectrometry methods. During the water treatment hydroxide precipitates are produced at the station, which are isolated using a sand filter, radium isotopes being coprecipitated alongside with them. As a result of this radioactive waste is accumulated at the station, radium isotope concentration in it being equivalent to radium isotope concentration in uranium-thorium ores with 0:11% uranium and 0.56% thorium content. radium isotope concentration in water, delivered to the user do not exceed the established domestic normatives do not exceed the established domestic normatives

Na, K, Ca, Mg, and U-series in fossil bone and the proposal of a radial diffusion–adsorption model of uranium uptake

International Nuclear Information System (INIS)

Cid, A.S.; Anjos, R.M.; Zamboni, C.B.; Cardoso, R.; Muniz, M.; Corona, A.; Valladares, D.L.

2014-01-01

Fossil bones are often the only materials available for chronological reconstruction of important archeological sites. However, since bone is an open system for uranium, it cannot be dated directly and therefore it is necessary to develop models for the U uptake. Hence, a radial diffusion–adsorption (RDA) model is described. Unlike the classic diffusion–adsorption (D–A) model, RDA uses a cylindrical geometry to describe the U uptake in fossil bones. The model was applied across a transverse section of a tibia of an extinct megamammal Macrauchenia patachonica from the La Paz Local Fauna, Montevideo State, Uruguay. Measurements of spatial distribution of Na, K, Ca, and Mg were also performed by neutron activation analysis (NAA). Gamma-ray spectrometric U-series dating was applied to determine the age of the bone sample. From U concentration profile, it was possible to observe the occurrence of a relatively slow and continuous uranium uptake under constant conditions that had not yet reached equilibrium, since the uranium distribution is a ∪-shaped closed-system. Predictions of the RDA model were obtained for a specific geochemical scenario, indicating that the effective diffusion coefficient D/R in this fossil bone is (2.4 ± 0.6)10 −12 cm 2 s −1 . Mean values of Na, K, Ca, and Mg contents along the radial line of the fossil tibia are consistent with the expected behavior for spatial distributions of these mineral elements across a modern bone section. This result indicates that the fossil tibia may have its mineral structure preserved. - Highlights: • The Radial diffusion–adsorption (RDA) model is described. • RDA uses a cylindrical geometry to describe the U uptake in fossil bones. • We show new data for an extinct Macrauchenia patachonica from Uruguay. • Spatial distributions of Na, K, Ca, Mg, and U across a fossil bone section. • Gamma-ray spectrometric U-series dating was applied to determine its age

Graphic and algebraic solutions of the discordant lead-uranium age problem

Science.gov (United States)

Stieff, L.R.; Stern, T.W.

1961-01-01

Uranium-bearing minerals that give lead-uranium and lead-lead ages that are essentially in agreement, i.e. concordant, generally are considered to have had a relatively simple geologic history and to have been unaltered since their deposition. The concordant ages obtained on such materials are, therefore, assumed to approach closely the actual age of the minerals. Many uranium-bearing samples, particularly uranium ores, give the following discordant age sequences; Pb206 U238 generation of radiogenic lead. The evaluation of discordant lead isotope age data may be separated into two operations. The first operation, with which this paper is concerned, is mechanical in nature and involves the calculation of the different possible concordant ages corresponding to the various processes assumed to have produced the discordant ages. The second operation is more difficult to define and requires, in part, some personal judgement. It includes a synthesis of the possible concordant age solutions with other independent geologic and isotopic evidence. The concordant age ultimately chosen as most acceptable should be consistent not only with the known events in the geologic history of the area, the age relations of the enclosing rocks, and the mineralogic and paragenetic evidence, but also with other independent age measurements and the isotopic data obtained on the lead in related or associated non-radioactive minerals. The calculation of the possible concordant ages from discordant age data has been greatly simplified by Wetherill's graphical method of plotting the mole ratios of radiogenic Pb206 U238 ( N206 N238) vs. radiogenic Pb207 U235 ( N207 N235) after correcting for the contaminating common Pb206 and Pb207. The linear relationships noted in this graphical procedure have been extended to plots of the mole ratios of total Pb206 U238 ( tN206 N238) vs. total Pb207 U235 ( tN207 N235). This modification permits the calculation of concordant ages for unaltered samples using

U-Pb isotopic evidence pertaining to the age and genesis of uranium mineralisation in Karoo sediments

International Nuclear Information System (INIS)

Allsopp, H.L.; Welke, H.J.; Armstrong, R.A.; Clough, W.; Evans, I.B.

1984-01-01

Preliminary investigations have been carried out, using the uranium-lead isotopic method, on the uranium mineralisation that occurs within the Karoo sediments. Two occurences were studied, namely the lower Beaufort sediments (Adelaide Subgroup) in the Beaufort West area and the Molteno Formation sediments in the Ficksburg area. The objective were to determine the age of the mineralisation and to study the mode of formation of the ores. The pattern of U-Pb apparent ages for all the Karoo samples is 207 Pb/ 206 Pb age >> 207 Pb* 235 U age > 206 Pb* 238 U age

Evaluating the effectiveness of dilution of the recovered uranium with depleted uranium and low-enriched uranium to obtain fuel for VVER reactors

International Nuclear Information System (INIS)

Smirnov, A Yu; Sulaberidze, G A; Dudnikov, A A; Nevinitsa, V A

2016-01-01

The possibility of the recovered uranium enrichment in a cascade of gas centrifuges with three feed flows (depleted uranium, low-enriched uranium, recovered uranium) with simultaneous dilution of U-232,234,236 isotopes was shown. A series of numerical experiments were performed for different content of U-235 in low-enriched uranium. It has been demonstrated that the selected combination of diluents can simultaneously reduce the cost of separative work and the consumption of natural uranium, not only with respect to the previously used multi-flow cascade schemes, but also in comparison to the standard cascade for uranium enrichment. (paper)

Uranium-series dating of the Mousterian occupation at Abric Romani, Spain

Energy Technology Data Exchange (ETDEWEB)

Bischoff, J L; Julia, R; Mora, R

1988-03-03

The precise evolutionary position of the Neanderthal people continues to be a major uncertainty in human evolution. Their origin and their relationship to anatomically modern people are unclear and are clouded by poor chronology. Lithic artefacts of the Mousterian type, found throughout Europe and the Mediterranean Basin, are believed to be the tool kit of the Neanderthals, but dates within Mousterian-bearing deposits are extremely rare. We report here on 20 high-quality uranium-series dates from Mousterian beds at Abric Romani, a rock shelter near Barcelona, Spain. The dates range from 39 to 60 kyr before present in an orderly stratigraphic succession and provide precise chronological control on an important Mousterian archaeological site.

Phospholyl-uranium complexes

International Nuclear Information System (INIS)

Gradoz, Philippe

1993-01-01

After having reported a bibliographical study on penta-methylcyclopentadienyl uranium complexes, and a description of the synthesis and radioactivity of uranium (III) and (IV) boron hydrides compounds, this research thesis reports the study of mono and bis-tetramethyl-phospholyl uranium complexes comprising chloride, boron hydride, alkyl and alkoxide ligands. The third part reports the comparison of structures, stabilities and reactions of homologue complexes in penta-methylcyclopentadienyl and tetramethyl-phospholyl series. The last part addresses the synthesis of tris-phospholyl uranium (III) and (IV) complexes. [fr

Development of an aging integrator for uranium-0.75 weight percent titanium alloy part aging control

International Nuclear Information System (INIS)

Howington, L.C.

1977-12-01

An instrumentation system (Aging Integrator) has been developed to provide more precise control of the heat-treatment process used on uranium-0.75 wt.% titanium alloy material. The Aging Integrator calculates the integral of a predetermined aging function to control the aging period in the heat-treatment process. This control was employed to compensate for discrepancies caused by variations in heatup times, furnace-control fluctuations, and disagreement as to the temperature at which aging actually starts. Although the Aging Integrator hardware has been installed and satisfactorily tested on a production-area furnace, sufficient data to estimate a statistically sound aging integration function will not be available for approximately one year

Review on the application of electron microprobe chemical dating method in the age research of uranium/pitchblende

International Nuclear Information System (INIS)

Ge Xiangkun; Qin Mingkuan; Fan Guang

2011-01-01

Different micro dating methods have been developed in recent years, the advantages and disadvantages are simply introduced at first. The recent development of electron microprobe chemical dating method in the age research of uraninite/pitchblende and the used analytical conditions by the precurser are presented in detail by stages. Finally, the application foreground of this method in the age research of uraninite/pitchblende and the possible problems are systematically investigated and discussed. It is believed that this method will play a big role in the age research of uranium minerals, especially in the micro dating research of tiny uranium minerals (φ < 10 μm) and uranium micro-ores of multi-stage. (authors)

Possible application of underground leaching of uranium in ''sandstone'' deposits by drilling method

International Nuclear Information System (INIS)

Bareja, E.

1988-01-01

Underground leaching as the method for excavation of uranium from its sandstone deposits is applied in many countries. A preliminary examination of a possible use of this method to sandstone deposits in Poland suggests it to be analysed against the uranium mineralization, noted within sediments of the Lower Triassic age in the Peribaltic Syneclise in the Krynica Morska - Paslek area. Before a definite decision on such exploitation of uranium, geologic and hydrogeologic conditions should be studied of individual uranium-bearing beds, particularly their permeability and insulation by impermeable claystone series as well as extraction of uranium from its bearing sandstones. The depth at which uranium-bearing beds occur, forms a very important item. The depth at which uranium ores described in literature and exploited by this method occur, does not exceed 700 m. 7 refs. (author)

Uranium disequilibrium dating of phosphate deposits from the Lau Group, Fiji

International Nuclear Information System (INIS)

Roe, K.K.; Burnett, W.C.

1983-01-01

A determination of the absolute age of two phosphate deposits in the Lau Group, Fiji by uranium-series disequilibrium techniques is reported. These measurements were undertaken in order to assist in the evaluation of their origin in terms of known palaeoclimatic information. (U.K.)

Uranium geochemistry and dating of Pacific island apatite

Energy Technology Data Exchange (ETDEWEB)

Roe, K K; Burnett, W C [Florida State Univ., Tallahassee (USA). Dept. of Oceanography

1985-07-01

Uranium-series disequilibrium dating of island phosphate deposits is evaluated in terms of known associated coral ages, uranium geochemistry, and stratigraphic sequences as well as the concordance between the geochronometers /sup 234/U//sup 238/U, /sup 230/Th//sup 234/U and /sup 226/Ra//sup 238/U. U(VI) is the predominant oxidation state of uranium in island phosphorites and by analogy to the youngest surficial deposits, most of the uranium initially bound is in the form of U(VI) sorbed by surfaces from seawater. Insular deposits contain more organic matter than even very young ocean floor samples and this leads to a greater probability of reduction of available recoil uranium than occurs in marine deposits. As a consequence, R(VI) <= R(T) <= R(VI), where R represents the /sup 234/U//sup 238/U activity ratio. This situation is completely opposite from that observed for marine-origin phosphorites. We determined that a fraction of U(VI) in ancient insular phosphorites is very labile and lost to alkaline carbonate solutions with a uranium activity ratio even more depleted in /sup 234/U than the bulk R(VI). The results are discussed.

How much uranium

International Nuclear Information System (INIS)

Kenward, M.

1976-01-01

Comment is made on the latest of a series of reports on world uranium resources from the OECD's Nuclear Energy Agency and the UN's International Atomic Energy Agency (Uranium resources, production and demand (including other nuclear fuel cycle data), published by the Organisation for Economic Cooperation and Development, Paris). The report categories uranium reserves by their recovery cost and looks at power demand and the whole of the nuclear fuel cycle, including uranium enrichment and spent fuel reprocessing. The effect that fluctuations in uranium prices have had on exploration for new uranium resources is considered. It is stated that increased exploration is essential considering the long lead times involved but that thanks to today's higher prices there are distinct signs that prospecting activities are increasing again. (U.K.)

Age of uranium ores at Ranger and Jabiluka unconformity vein deposits, Northern Territory, Australia

International Nuclear Information System (INIS)

Ludwig, K.R.; Grauch, R.I.; Nutt, C.J.; Frishman, D.; Nash, J.T.; Simmons, K.R.

1985-01-01

The Ranger and Jabiluka uranium deposits are the largest in the Alligator Rivers Uranium Field (ARUF), which contains at least 20% of the world's low-cost uranium reserves. Ore occurs in early Proterozoic metasediments, below an unconformity with sandstones of the 1.65 Ga Kombolgie Formation. This study uses U-Pb isotope data from over 60 whole-rock drill core samples that contained a variety of mineral assemblages and textures. Data for Ranger samples indicate a well-defined age of 1.74 +/-.02 Ga. This 1.74 Ga age is distinctly pre-Kombolgie, so the Ranger deposit cannot have been formed by processes requiring its presence. This Ranger age is consistent, however, with mineralization related to heating associated with either the emplacement of early post-metamorphic granites, or possibly with intrusion of the nearby Oenpelli Dolerite. In contrast, data for the least-altered Jabiluka ores yield a concordia-intercept age of 1.44 +/-.02 Ga--significantly younger than the Ranger age, and also younger than the Komobolgie. This age may correspond to a regional thermal event, as indicated both by mafic dikes of roughly this age and a zircon lower-intercept age from a nearby granite-gneiss. Thus, together with the well-defined ∼900 Ma age of ores at the Nabarlek deposit, there are at least 3 distinct periods of major U-mineralization in the ARUF. Data for both Ranger and Jabiluka indicate the same, profound isotopic disturbance at some time in the interval of 0.4-0.6 Ga. Possibly this time corresponds to the development of basins and associated basalt flows to the W and SW, a suggested by Crick et. al. (1980)

Measurement of radionuclide activities of uranium-238 series in soil samples by gamma spectrometry: case of Vinaninkarena

International Nuclear Information System (INIS)

Randrianantenaina, F.R.

2017-01-01

The aim of this work is to determine the activity level of radionuclides of uranium-238 series. Eight soil samples are collected at Rural Commune of Vinaninkarena. After obtaining secular equilibrium, these samples have been measured using gamma spectrometry system in the Nuclear Analyses and Techniques Department of INSTN-Madagascar, with HPGe detector (30 % relative efficiency) and a Genie 2000 software. Activities obtained vary from (78±2)Bq.kg -1 to (49 231 ± 415)Bq.kg -1 . Among these eight samples, three activity levels are shown. Low activity is an activity which has value lower or equal to (89±3)Bq.kg -1 . Average activity is an activity which has value between (186± 1)Bq.kg -1 and (1049 ±7)Bq.kg -1 . And high activity is an activity which has value higher or equal to (14501±209)Bq.kg -1 . According to UNSCEAR 2000, these value are all higher than the world average value which is 35 Bq.kg -1 .It is due to the localities of sampling points. The variation of the activity level depends on radionuclide concentration of uranium-238 series in the soil. [fr

Age, sedimentary environments, and other aspects of sandstone and related host rocks for uranium deposits

International Nuclear Information System (INIS)

1983-01-01

Project II of the Uranium Geology Working Group was assigned to the study of sedimentary basins and sandstone - type uranium deposits. About 40% of the worlds's uranium resources are contained in sandstone-type deposits, which has led to extensive research. The research was carried out mainly by correspondence, and the results reported by 21 geologists from 10 nations are summarized in this report. It investigated five topics dealing with important aspects of the geology of uranium ores in sandstone host formations: age of host rock; partitioning of uranium between continental and marine sediments; latitude limitation on formation of sandstone deposits; effect of rock formation dip on sandstone ores; usefulness of stable isotope and fluid inclusion studies. The results of studies on these subjects form part of a wider programme of the Working Group, whose final results will be presented at the 27th International Geological Congress in Moscow in 1984

Uranium series isotopes concentration in sediments at San Marcos and Luis L. Leon reservoirs, Chihuahua, Mexico

Science.gov (United States)

Méndez-García, C.; Renteria-Villalobos, M.; García-Tenorio, R.; Montero-Cabrera, M. E.

2014-07-01

Spatial and temporal distribution of the radioisotopes concentrations were determined in sediments near the surface and core samples extracted from two reservoirs located in an arid region close to Chihuahua City, Mexico. At San Marcos reservoir one core was studied, while from Luis L. Leon reservoir one core from the entrance and another one close to the wall were investigated. 232Th-series, 238U-series, 40K and 137Cs activity concentrations (AC, Bq kg-1) were determined by gamma spectrometry with a high purity Ge detector. 238U and 234U ACs were obtained by liquid scintillation and alpha spectrometry with a surface barrier detector. Dating of core sediments was performed applying CRS method to 210Pb activities. Results were verified by 137Cs AC. Resulting activity concentrations were compared among corresponding surface and core sediments. High 238U-series AC values were found in sediments from San Marcos reservoir, because this site is located close to the Victorino uranium deposit. Low AC values found in Luis L. Leon reservoir suggest that the uranium present in the source of the Sacramento - Chuviscar Rivers is not transported up to the Conchos River. Activity ratios (AR) 234U/overflow="scroll">238U and 238U/overflow="scroll">226Ra in sediments have values between 0.9-1.2, showing a behavior close to radioactive equilibrium in the entire basin. 232Th/overflow="scroll">238U, 228Ra/overflow="scroll">226Ra ARs are witnesses of the different geological origin of sediments from San Marcos and Luis L. Leon reservoirs.

Uranium series isotopes concentration in sediments at San Marcos and Luis L. Leon reservoirs, Chihuahua, Mexico

International Nuclear Information System (INIS)

Méndez-García, C.; Montero-Cabrera, M. E.; Renteria-Villalobos, M.; García-Tenorio, R.

2014-01-01

Spatial and temporal distribution of the radioisotopes concentrations were determined in sediments near the surface and core samples extracted from two reservoirs located in an arid region close to Chihuahua City, Mexico. At San Marcos reservoir one core was studied, while from Luis L. Leon reservoir one core from the entrance and another one close to the wall were investigated. 232 Th-series, 238 U-series, 40 K and 137 Cs activity concentrations (AC, Bq kg −1 ) were determined by gamma spectrometry with a high purity Ge detector. 238 U and 234 U ACs were obtained by liquid scintillation and alpha spectrometry with a surface barrier detector. Dating of core sediments was performed applying CRS method to 210 Pb activities. Results were verified by 137 Cs AC. Resulting activity concentrations were compared among corresponding surface and core sediments. High 238 U-series AC values were found in sediments from San Marcos reservoir, because this site is located close to the Victorino uranium deposit. Low AC values found in Luis L. Leon reservoir suggest that the uranium present in the source of the Sacramento – Chuviscar Rivers is not transported up to the Conchos River. Activity ratios (AR) 234 U/ 238 U and 238 U/ 226 Ra in sediments have values between 0.9–1.2, showing a behavior close to radioactive equilibrium in the entire basin. 232 Th/ 238 U, 228 Ra/ 226 Ra ARs are witnesses of the different geological origin of sediments from San Marcos and Luis L. Leon reservoirs

Method of fabricating a uranium-bearing foil

Science.gov (United States)

Gooch, Jackie G [Seymour, TN; DeMint, Amy L [Kingston, TN

2012-04-24

Methods of fabricating a uranium-bearing foil are described. The foil may be substantially pure uranium, or may be a uranium alloy such as a uranium-molybdenum alloy. The method typically includes a series of hot rolling operations on a cast plate material to form a thin sheet. These hot rolling operations are typically performed using a process where each pass reduces the thickness of the plate by a substantially constant percentage. The sheet is typically then annealed and then cooled. The process typically concludes with a series of cold rolling passes where each pass reduces the thickness of the plate by a substantially constant thickness amount to form the foil.

Sequential extraction of uranium metal contamination

International Nuclear Information System (INIS)

Murry, M.M.; Spitz, H.B.; Connick, W.B.

2016-01-01

Samples of uranium contaminated dirt collected from the dirt floor of an abandoned metal rolling mill were analyzed for uranium using a sequential extraction protocol involving a series of five increasingly aggressive solvents. The quantity of uranium extracted from the contaminated dirt by each reagent can aid in predicting the fate and transport of the uranium contamination in the environment. Uranium was separated from each fraction using anion exchange, electrodeposition and analyzed by alpha spectroscopy analysis. Results demonstrate that approximately 77 % of the uranium was extracted using NH 4 Ac in 25 % acetic acid. (author)

Discussion on the genesis and mineralization of sandstone type uranium deposit in the southern-central Longchuanjiang basin, western Yunnan province

International Nuclear Information System (INIS)

Cai Yuqi; Li Mangen

2002-01-01

The author mainly discusses the character of the depositional systems, geological structures and ore-bearing series in the south-central Longchuanjiang basin, and points out that the uranium mineralization is closely related to the two depositional discontinuities caused by the tectonic evolution. Based on the characteristics of uranium mineralization in the area, pitchblende, uranium blacks and phosphuranylite are discovered in No. 382 uranium deposit and radiometric super-micro-minerals in No. 381 deposit. The research on the uranium mineralization age in No. 382 deposit shows that the mineralization in the south-central part of the basin has genetically multi-staged

Measuring small time periods in earth sciences by uranium series disequilibrium

International Nuclear Information System (INIS)

Choudhary, A.K.

2008-01-01

During the last three decades mass spectrometry in India has seen its application in almost every field of science. In particular, TIMS has revolutionized geological sciences by taking it from a mainly descriptive to modern quantitative Earth Sciences. It has largely contributed in measurement of precise time scales of geological processes. During the last decade, focus has primarily been on measurement of time scales of these fundamental processes. Some of the radiometric methods initially developed for measuring shorter time-scales have their own problems. The intermediate nuclides in the uranium and thorium decay series having much shorter half lives compared to their parents, provide a useful tool to measure intermediate time scales. These isotopes had earlier been ignored due to analytical difficulties associated with their measurement. The development of new generation mass spectrometers with very high abundance sensitivity has now made it possible to measure these isotopic ratios. Consequently U-series isotopic measurements have put unique and at times the only quantitative constraints on the processes taking place in the interior of the Earth. Since such mass spectrometers have recently been installed in some of the laboratories in India, scientific investigation may now be taken up in some of the unexplored areas of Earth Sciences in our country

Retrospective - the beginnings of the uranium industry

International Nuclear Information System (INIS)

Anon.

1994-01-01

This article is a historical perspective of the uranium industry, from the discovery of uranium in 1789 to the discovery of fission in 1939. It is the first in a series of articles. In this part of the series, the initial discovery of uranium is mentioned. Early ore discoveries, especially in the USA, are also noted, and the market conditions at the end of the 19th century are reviewed. Shortly after the discovery of radium in 1898 and natural radioactivity, the connection between uranium and radium was noted, and this is outlined in the article. Due to the intimate relationship between the two elements, radium product and radium markets are also reviewed

REIMEP-22 inter-laboratory comparison: "U Age Dating - Determination of the production date of a uranium certified test sample"

OpenAIRE

VENCHIARUTTI CELIA; VARGA ZSOLT; RICHTER Stephan; JAKOPIC Rozle; MAYER Klaus; AREGBE Yetunde

2015-01-01

The REIMEP-22 inter-laboratory comparison aimed at determining the production date of a uranium certified test sample (i.e. the last chemical separation date of the material). Participants in REIMEP-22 on "U Age Dating - Determination of the production date of a uranium certified test sample" received one low-enriched 20 mg uranium sample for mass spectrometry measurements and/or one 50 mg uranium sample for D-spectrometry measurements, with an undisclosed value for the production date. They ...

Na, K, Ca, Mg, and U-series in fossil bone and the proposal of a radial diffusion-adsorption model of uranium uptake.

Science.gov (United States)

Cid, A S; Anjos, R M; Zamboni, C B; Cardoso, R; Muniz, M; Corona, A; Valladares, D L; Kovacs, L; Macario, K; Perea, D; Goso, C; Velasco, H

2014-10-01

Fossil bones are often the only materials available for chronological reconstruction of important archeological sites. However, since bone is an open system for uranium, it cannot be dated directly and therefore it is necessary to develop models for the U uptake. Hence, a radial diffusion-adsorption (RDA) model is described. Unlike the classic diffusion-adsorption (D-A) model, RDA uses a cylindrical geometry to describe the U uptake in fossil bones. The model was applied across a transverse section of a tibia of an extinct megamammal Macrauchenia patachonica from the La Paz Local Fauna, Montevideo State, Uruguay. Measurements of spatial distribution of Na, K, Ca, and Mg were also performed by neutron activation analysis (NAA). Gamma-ray spectrometric U-series dating was applied to determine the age of the bone sample. From U concentration profile, it was possible to observe the occurrence of a relatively slow and continuous uranium uptake under constant conditions that had not yet reached equilibrium, since the uranium distribution is a ∪-shaped closed-system. Predictions of the RDA model were obtained for a specific geochemical scenario, indicating that the effective diffusion coefficient D/R in this fossil bone is (2.4 ± 0.6)10(-12) cm(2)s(-1). Mean values of Na, K, Ca, and Mg contents along the radial line of the fossil tibia are consistent with the expected behavior for spatial distributions of these mineral elements across a modern bone section. This result indicates that the fossil tibia may have its mineral structure preserved. Copyright © 2014 Elsevier Ltd. All rights reserved.

Accelerated aging tests of liners for uranium mill tailings disposal

International Nuclear Information System (INIS)

Barnes, S.M.; Buelt, J.L.; Hale, V.Q.

1981-11-01

This document describes the results of accelerated aging tests to determine the long-term effectiveness of selected impoundment liner materials in a uranium mill tailings environment. The study was sponsored by the US Department of Energy under the Uranium Mill Tailings Remedial Action Project. The study was designed to evaluate the need for, and the performance of, several candidate liners for isolating mill tailings leachate in conformance with proposed Environmental Protection Agency and Nuclear Regulatory Commission requirements. The liners were subjected to conditions known to accelerate the degradation mechanisms of the various liners. Also, a test environment was maintained that modeled the expected conditions at a mill tailings impoundment, including ground subsidence and the weight loading of tailings on the liners. A comparison of installation costs was also performed for the candidate liners. The laboratory testing and cost information prompted the selection of a catalytic airblown asphalt membrane and a sodium bentonite-amended soil for fiscal year 1981 field testing

ALPHA SPECTROMETRIC EVALUATION OF SRM-995 AS A POTENTIAL URANIUM/THORIUM DOUBLE TRACER SYSTEM FOR AGE-DATING URANIUM MATERIALS

Energy Technology Data Exchange (ETDEWEB)

Beals, D.

2011-12-06

Uranium-233 (t{sub 1/2} {approx} 1.59E5 years) is an artificial, fissile isotope of uranium that has significant importance in nuclear forensics. The isotope provides a unique signature in determining the origin and provenance of uranium-bearing materials and is valuable as a mass spectrometric tracer. Alpha spectrometry was employed in the critical evaluation of a {sup 233}U standard reference material (SRM-995) as a dual tracer system based on the in-growth of {sup 229}Th (t{sub 1/2} {approx} 7.34E3 years) for {approx}35 years following radiochemical purification. Preliminary investigations focused on the isotopic analysis of standards and unmodified fractions of SRM-995; all samples were separated and purified using a multi-column anion-exchange scheme. The {sup 229}Th/{sup 233}U atom ratio for SRM-995 was found to be 1.598E-4 ({+-} 4.50%) using recovery-corrected radiochemical methods. Using the Bateman equations and relevant half-lives, this ratio reflects a material that was purified {approx} 36.8 years prior to this analysis. The calculated age is discussed in contrast with both the date of certification and the recorded date of last purification.

Separation of uranium in bone rest for their dating; Separacion de uranio en restos oseos para la datacion de estos

Energy Technology Data Exchange (ETDEWEB)

Garcia R, G.; Ordonez R, E.; Tenorio, D.; Cordoba, L. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, Mexico D.F. (Mexico)

2001-07-01

The uranium (U) and thorium (Th) recovery, as fundamental part of the 'uranium serie' technique is an alternative method for dating of bone rests in Mexico. That so is how it has been possible its application for dating geological material and in this research it has been determined the age of some mammoth samples from the basin of Mexico valley. (Author)

Recovery and purification of uranium-234 from aged plutonium-238

International Nuclear Information System (INIS)

Keister, P.L.; Figgins, P.W.; Watrous, R.M.

1978-01-01

The current production methods used to recover and purify uranium-234 from aged plutonium-238 at Mound Laboratory are presented. The three chemical separation steps are described in detail. In the initial separation step, the bulk of the plutonium is precipitated as the oxalate. Successively lower levels of plutonium are achieved by anion exchange in nitrate media and by anion exchange in chloride media. The procedures used to characterize and analyze the final U 3 O 8 are given

U uranium. Suppl. Vol. D3

International Nuclear Information System (INIS)

Haug, H.O.

1982-01-01

This volume of the uranium series of the Gmelin handbook deals with the anion exchange of uranium. Compounds of the valence states of III, IV, V and VI of uranium in halide, nitrate, sulfate, phosphate, and carbonate media as well as in media containing organic complexing agents are treated. The literature cited covers the period from about 1947 to the end of 1980. (RB) [de

Uranium series isotopes concentration in sediments at San Marcos and Luis L. Leon reservoirs, Chihuahua, Mexico

Energy Technology Data Exchange (ETDEWEB)

Méndez-García, C.; Montero-Cabrera, M. E., E-mail: elena.montero@cimav.edu.mx [Centro de Investigación en Materiales Avanzados, CIMAV, Miguel de Cervantes 120, 31109, Chihuahua, Chihuahua (Mexico); Renteria-Villalobos, M. [Facultad de Zootecnia y Ecología Universidad Autónoma de Chihuahua, Periferico Francisco R. Almada Km 1, 31410, Chihuahua (Mexico); García-Tenorio, R. [Applied Nuclear Physics Group, University of Seville, ETS Arquitectura, Avda. Reina Mercedes s/n, 41012 Seville (Spain)

2008-01-01

Spatial and temporal distribution of the radioisotopes concentrations were determined in sediments near the surface and core samples extracted from two reservoirs located in an arid region close to Chihuahua City, Mexico. At San Marcos reservoir one core was studied, while from Luis L. Leon reservoir one core from the entrance and another one close to the wall were investigated. ²³²Th-series, ²³⁸U-series, ⁴⁰K and ¹³⁷Cs activity concentrations (AC, Bq kg⁻¹) were determined by gamma spectrometry with a high purity Ge detector. ²³⁸U and ²³⁴U ACs were obtained by liquid scintillation and alpha spectrometry with a surface barrier detector. Dating of core sediments was performed applying CRS method to ²¹⁰Pb activities. Results were verified by ¹³⁷Cs AC. Resulting activity concentrations were compared among corresponding surface and core sediments. High ²³⁸U-series AC values were found in sediments from San Marcos reservoir, because this site is located close to the Victorino uranium deposit. Low AC values found in Luis L. Leon reservoir suggest that the uranium present in the source of the Sacramento – Chuviscar Rivers is not transported up to the Conchos River. Activity ratios (AR) ²³⁴U/²³⁸U and ²³⁸U/²²⁶Ra in sediments have values between 0.9–1.2, showing a behavior close to radioactive equilibrium in the entire basin. ²³²Th/²³⁸U, ²²⁸Ra/²²⁶Ra ARs are witnesses of the different geological origin of sediments from San Marcos and Luis L. Leon reservoirs.

Improvements on heap leaching process for a refractory uranium ore and yellow cake precipitation process

International Nuclear Information System (INIS)

Feng Jianke

2013-01-01

Some problems such as formed harden matrix, ore heap compaction, poor permeability, and agglomeration of absorption resin occur during extracting uranium from a refractory uranium ore by heap leaching process. After some measures were taken, i.e. spraying a new ore heap by low concentration acid, two or more ore heaps in series leaching, turning ores in ore heap, the permeability was improved, acid consumption was reduced. Through precipitate circulation and aging, the yellow cake slurry in amorphous or microlite form was transformed to crystal precipitate, thus uranium content in yellow cake was improved, and water content in yellow cake was lowered with good economic benefits. (author)

The relational of Mesozoic volcanism to uranium mineralization in Guyuan-Hongshanzi area

International Nuclear Information System (INIS)

Wu Rengui; Xu Zhe; Yu Zhenqing; Jiang Shan; Shen Kefeng

2011-01-01

Based on the time of Mesozoic volcanism,the characteristic of major and trace element, and REE pattern of the volcanic rocks in Guyuan-Hongshanzi area, The Mesozoic volcanism can be divided into the early cycle and later cycle during the Early Cretaceous, and it's magma series is classified in two sub-series, one is alkaline series of trachyte dominated and another is subalkaline series of rhyolite dominated. The relations between Mesozoic volcanism and uranium mineralization is mainly shown in four aspects: (1) Uranium mineralization controlled by the coexist of two magma series; (2) Uranium mineralization controlled by superhypabyssal porphyry body in later cycle volcanism during the Early Cretaceous; (3) The porphyry body close to uranium mineralization,bearing the genesis characteristics of crust-mantle action; and (4) High Si and K content in the chemical composition of the mineralization volcanic rocks. (authors)

EPR of uranium ions

International Nuclear Information System (INIS)

Ursu, I.; Lupei, V.

1984-02-01

A review of the electron paramagnetic resonance data on the uranium ions is given. After a general account of the electronic structure of the uranium free atoms and ions, the influence of the external fields (magnetic field, crystal fields) is discussed. The main information obtained from EPR studies on the uranium ions in crystals are emphasized: identification of the valence and of the ground electronic state, determination of the structure of the centers, crystal field effects, role of the intermediate coupling and of the J-mixing, role of the covalency, determination of the nuclear spin, maqnetic dipole moment and electric quadrupole moment of the odd isotopes of uranium. These data emphasize the fact that the actinide group has its own identity and this is accutely manifested at the beginning of the 5fsup(n) series encompassed by the uranium ions. (authors)

Calculation and analysis for a series of enriched uranium bare sphere critical assemblies

International Nuclear Information System (INIS)

Yang Shunhai

1994-12-01

The imported reactor fuel assembly MARIA program system is adapted to CYBER 825 computer in China Institute of Atomic Energy, and extensively used for a series of enriched uranium bare sphere critical assemblies. The MARIA auxiliary program of resonance modification MA is designed for taking account of the effects of resonance fission and absorption on calculated results. By which, the multigroup constants in the library attached to MARIA program are revised based on the U.S. Evaluated Nuclear Data File ENDF/B-IV, the related nuclear data files are replaced. And then, the reactor geometry buckling and multiplication factor are given in output tapes. The accuracy of calculated results is comparable with those of Monte Carlo and Sn method, and the agreement with experiment result is in 1%. (5 refs., 4 figs., 3 tabs.)

Radiological chronometry of uranium metal samples

International Nuclear Information System (INIS)

Meyers, L.A.; Stalcup, A.M.; Glover, S.E.; Spitz, H.B.; LaMont, S.P.

2014-01-01

Radiological chronometry is an important tool in nuclear forensics that uses several methods to determine the length of time that has elapsed since a material was last purified. One of the chronometers used in determining the age of metallic uranium involves measuring the fractional ingrowth of 230 Th from its parent 234 U with the assumption that the uranium metal contained no impurities, especially thorium, when it was purified. The affects of different etching procedures were evaluated for the removal of surface oxidation with three different types of uranium metal samples to determine whether the etching procedure affects the radiological age. The sample treated with a rigorous etching procedure had exhibited the most reliable radiological age while less rigorous etching yields a radiological age from 15 years to hundreds of years older than the known age. Any excess thorium on the surface of a uranium metal sample presents a bias in age determination and the sample will appear older than the true age. Although this research demonstrates the need for rigorous surface etching, a bias in the radiological age could have arisen if the uranium in the metal was heterogeneously distributed. (author)

Uranium distribution in Brazilian granitic rocks. Identification of uranium provinces

International Nuclear Information System (INIS)

Tassinari, C.G.G.

1993-01-01

The research characterized and described uranium enriched granitoids in Brazil. They occur in a variety of tectonic environments and are represented by a variety granite types of distinct ages. It may be deduced that in general they have been generated by partial melting process of continental crust. However, some of them, those with tonality composition, indicate a contribution from mantle derived materials, thus suggesting primary uranium enrichment from the upper mantle. Through this study, the identification and characterization of uranium enriched granite or uranium provinces in Brazil can be made. This may also help identify areas with potential for uranium mineralization although it has been note that uranium mineralization in Brazil are not related to the uranium enrichment process. In general the U-anomalous granitoids are composed of granites with alkaline composition and granite ''sensu strictu'' which comprise mainly of syenites, quartz-syenites and biotite-hornblende granites, with ages between 1,800 - 1,300 M.a. The U-anomalous belongings to this period present high Sr initial ratios values, above 0.706, and high Rb contents. Most of the U-enriched granitoids occur within ancient cratonic areas, or within Early to Mid-Proterozoic mobile belts, but after their cratonization. Generally, these granitoids are related to the border zones of the mobile belts or deep crustal discontinuity. Refs, 12 figs, 3 tabs

Sedimentary uranium deposits in France and French Union

International Nuclear Information System (INIS)

Kervella, F.

1958-01-01

The author gives the actual state of our knowledge on uranium deposits found in recent years. Till now in precambrian formations only one important deposit has been found, at Mounana (Gabon) in a series of conglomeratic sandstones belonging to the 'Francevillien'. The observed mineralization is of the uranium-vanadium type. To the carboniferous formations corresponds in France a series of deposits, among which the most important ones are located at Saint-Hippolyte. Uranium as carburans, organic-bound complexes, is contained in lacustrine schists of Westphalian or lower Stephanian formations. A number of occurrences are also known in permo-triassic formations, particularly in the Vanoise Alps, in the Maritime Alps and in the Herault, where important occurrences have recently been found not far from Lodeve. The cretaceous and tertiary systems contain uranium deposits in phosphate rocks (Morocco, Senegal, Togo, Middle-Congo). Two sedimentary oligocene deposits are known in France. Lastly, the Vinaninkarena deposit in Madagascar, known for a long time, is the only important one reported in the quaternary series. (author) [fr

Similarity estimators for irregular and age uncertain time series

Science.gov (United States)

Rehfeld, K.; Kurths, J.

2013-09-01

Paleoclimate time series are often irregularly sampled and age uncertain, which is an important technical challenge to overcome for successful reconstruction of past climate variability and dynamics. Visual comparison and interpolation-based linear correlation approaches have been used to infer dependencies from such proxy time series. While the first is subjective, not measurable and not suitable for the comparison of many datasets at a time, the latter introduces interpolation bias, and both face difficulties if the underlying dependencies are nonlinear. In this paper we investigate similarity estimators that could be suitable for the quantitative investigation of dependencies in irregular and age uncertain time series. We compare the Gaussian-kernel based cross correlation (gXCF, Rehfeld et al., 2011) and mutual information (gMI, Rehfeld et al., 2013) against their interpolation-based counterparts and the new event synchronization function (ESF). We test the efficiency of the methods in estimating coupling strength and coupling lag numerically, using ensembles of synthetic stalagmites with short, autocorrelated, linear and nonlinearly coupled proxy time series, and in the application to real stalagmite time series. In the linear test case coupling strength increases are identified consistently for all estimators, while in the nonlinear test case the correlation-based approaches fail. The lag at which the time series are coupled is identified correctly as the maximum of the similarity functions in around 60-55% (in the linear case) to 53-42% (for the nonlinear processes) of the cases when the dating of the synthetic stalagmite is perfectly precise. If the age uncertainty increases beyond 5% of the time series length, however, the true coupling lag is not identified more often than the others for which the similarity function was estimated. Age uncertainty contributes up to half of the uncertainty in the similarity estimation process. Time series irregularity

Similarity estimators for irregular and age-uncertain time series

Science.gov (United States)

Rehfeld, K.; Kurths, J.

2014-01-01

Paleoclimate time series are often irregularly sampled and age uncertain, which is an important technical challenge to overcome for successful reconstruction of past climate variability and dynamics. Visual comparison and interpolation-based linear correlation approaches have been used to infer dependencies from such proxy time series. While the first is subjective, not measurable and not suitable for the comparison of many data sets at a time, the latter introduces interpolation bias, and both face difficulties if the underlying dependencies are nonlinear. In this paper we investigate similarity estimators that could be suitable for the quantitative investigation of dependencies in irregular and age-uncertain time series. We compare the Gaussian-kernel-based cross-correlation (gXCF, Rehfeld et al., 2011) and mutual information (gMI, Rehfeld et al., 2013) against their interpolation-based counterparts and the new event synchronization function (ESF). We test the efficiency of the methods in estimating coupling strength and coupling lag numerically, using ensembles of synthetic stalagmites with short, autocorrelated, linear and nonlinearly coupled proxy time series, and in the application to real stalagmite time series. In the linear test case, coupling strength increases are identified consistently for all estimators, while in the nonlinear test case the correlation-based approaches fail. The lag at which the time series are coupled is identified correctly as the maximum of the similarity functions in around 60-55% (in the linear case) to 53-42% (for the nonlinear processes) of the cases when the dating of the synthetic stalagmite is perfectly precise. If the age uncertainty increases beyond 5% of the time series length, however, the true coupling lag is not identified more often than the others for which the similarity function was estimated. Age uncertainty contributes up to half of the uncertainty in the similarity estimation process. Time series irregularity

The discovery and character of Pleistocene calcrete uranium deposits in the Southern High Plains of west Texas, United States

Science.gov (United States)

Van Gosen, Bradley S.; Hall, Susan M.

2017-12-18

This report describes the discovery and geology of two near-surface uranium deposits within calcareous lacustrine strata of Pleistocene age in west Texas, United States. Calcrete uranium deposits have not been previously reported in the United States. The west Texas uranium deposits share characteristics with some calcrete uranium deposits in Western Australia—uranium-vanadium minerals hosted by nonpedogenic calcretes deposited in saline lacustrine environments.In the mid-1970s, Kerr-McGee Corporation conducted a regional uranium exploration program in the Southern High Plains province of the United States, which led to the discovery of two shallow uranium deposits (that were not publicly reported). With extensive drilling, Kerr-McGee delineated one deposit of about 2.1 million metric tons of ore with an average grade of 0.037 percent U3O8 and another deposit of about 0.93 million metric tons of ore averaging 0.047 percent U3O8.The west-Texas calcrete uranium-vanadium deposits occur in calcareous, fine-grained sediments interpreted to be deposited in saline lakes formed during dry interglacial periods of the Pleistocene. The lakes were associated with drainages upstream of a large Pleistocene lake. Age determinations of tephra in strata adjacent to one deposit indicate the host strata is middle Pleistocene in age.Examination of the uranium-vanadium mineralization by scanning-electron microscopy indicated at least two generations of uranium-vanadium deposition in the lacustrine strata identified as carnotite and a strontium-uranium-vanadium mineral. Preliminary uranium-series results indicate a two-component system in the host calcrete, with early lacustrine carbonate that was deposited (or recrystallized) about 190 kilo-annum, followed much later by carnotite-rich crusts and strontium-uranium-vanadium mineralization in the Holocene (about 5 kilo-annum). Differences in initial 234U/238U activity ratios indicate two separate, distinct fluid sources.

A rapid in situ method for determining the ages of uranium oxide minerals: Evolution of the Cigar Lake deposit, Athabasca Basin

International Nuclear Information System (INIS)

Fayek, M.; Harrison, T.M.; Grove, M.; Coath, C.D.

2000-01-01

The authors present a rapid and accurate technique for making in situ U-Pb isotopic measurements of uranium oxide minerals that utilizes both electron and ion microprobes. U and Pb concentrations are determined using an electron microprobe, whereas the isotopic composition of Pb for the same area is measured using a high-resolution ion microprobe. The advantages of this approach are: mineral separation and chemical digestion are unnecessary; homogeneous uranium oxide standards, which are difficult to obtain, are not required; and precise and accurate U-Pb ages on ∼10 microm spots can be obtained in a matter of hours. The authors have applied their method to study the distribution of U-Pb ages in complexly intergrown uranium oxides from the unconformity-type Cigar Lake uranium deposit, Saskatchewan, Canada. In situ U-Pb results from early formed uraninite define a well-correlated array on concordia with upper and lower intercepts of 1,467 ± 63 Ma and 443 ± 96 Ma (±1σ), respectively. The 1,467 Ma age is interpreted as the minimum age of mineralization and is consistent with the age of clay-mineral alteration (approximately1477 Ma) and magnetization of diagenetic hematite (1,650 to 1,450 Ma) that is associated with these unconformity-type uranium deposits and early diagenesis of the Athabasca Basin sediments. In situ U-Pb isotopic analysis of uraninite and coffinite can document the Pb*/U heterogeneities that can occur on a scale of 15 to 30 microm, thus providing relatively accurate information regarding the timing of fluid interactions associated with the evolution of these deposits

Manual on laboratory testing for uranium ore processing

International Nuclear Information System (INIS)

1990-01-01

Laboratory testing of uranium ores is an essential step in the economic evaluation of uranium occurrences and in the development of a project for the production of uranium concentrates. Although these tests represent only a small proportion of the total cost of a project, their proper planning, execution and interpretation are of crucial importance. The main purposes of this manual are to discuss the objectives of metallurgical laboratory ore testing, to show the specific role of these tests in the development of a project, and to provide practical instructions for performing the tests and for interpreting their results. Guidelines on the design of a metallurgical laboratory, on the equipment required to perform the tests and on laboratory safety are also given. This manual is part of a series of Technical Reports on uranium ore processing being prepared by the IAEA's Division of Nuclear Fuel Cycle and Waste Management. A report on the Significance of Mineralogy in the Development of Flowsheets for Processing Uranium Ores (Technical Reports Series No. 196, 1980) and an instruction manual on Methods for the Estimation of Uranium Ore Reserves (No. 255, 1985) have already been published. 17 refs, 40 figs, 17 tabs

Dating of the Francevillian sedimentary series and mineralogic and isotopic (Sm, Nd, Rb, Sr, K, Ar, U, O and C) characterization of the gangue of the reactors 10 and 13. Preliminary report

International Nuclear Information System (INIS)

Gautier-Lafaye, F.; Stille, P.; Bros, R.; Taieb, R.

1993-01-01

This paper summarizes the various ages reported for the diagenetic events in the Francevillian sedimentary series (Precambrian era) and the fission reactors of Oklo. Obviously, differences exist between the ages obtained on the silicate minerals and the ages obtained on the Uranium ores and on the reactors. Clay minerals which crystallized during the fission reactions yield younger ages than the reactors themselves. Similarly, the diagenetic clays (1870 Ma) show younger ages than the Uranium ores (2000 Ma). This is in contrast to mineralogical and field evidence indicating that Uranium mineralization occurred during diagenesis of the Francevillian sediments. These antithetical results give rise to several questions. Does the age obtained on the diagenetic clays date a late thermal event or does the age of the Uranium mineralization reflect a multistage U-Pb history. This work tries to bring answers with the help of new isotopic analysis and studies mineralogy of the gangue of reactors and isotopic compositions in Uranium ores. 8 refs., 4 figs

Surficial uranium deposits in Somalia

International Nuclear Information System (INIS)

Briot, P.

1984-01-01

Surficial uranium deposits in Somalia are of the valley-fill calcrete type and occur in the arid Mudugh Province of the Dusa Mareb-El Bur region. They are located in a belt about 240 km in length which is orientated parallel to the north-south regional tectonic framework. The uranium resources of the region amount to about 5,000 t U 3 O 8 at an average grade of 0.1% U 3 O 8 . Basement rocks constitute a 7,000 m thick succession of Jurassic to Quaternary sediments of the Somalian Basin. Uranium mineralization in the form of carnotite occurs in the uppermost Mercia Series. The origin of the uranium and vanadium is unclear due to a shortage of the favourable source rocks. (author)

Short-term uranium price formation: a methodology

International Nuclear Information System (INIS)

Hsieh, L.Y.; de Graffenried, C.L.

1987-01-01

One of the major problems in analyzing the short-term uranium market is the lack of a well-defined spot market price. The two primary sources of price data covering the US uranium market are the series published by the US Dept. of Energy (DOE) and by the Nuclear Exchange Corporation (NUEXCO), a private brokerage firm. Because of the differences in both definition and coverage, these two series are not directly comparable. In this study, an econometric model was developed for analyzing the interrelationship between short-term uranium price (NUEXCO exchange value), supply, demand, and future price expectations formed by market participants. The validity of this model has been demonstrated by the fact that all simulation statistics derived are highly significant. Three forecasting scenarios were developed in this study

A device for uranium series leaching from glass fiber in HEPA filter

International Nuclear Information System (INIS)

Gye-Nam Kim; Hye-Min Park; Wang-Kyu Choi; Jei-Kwon Moon

2012-01-01

For the disposal of a high efficiency particulate air (HEPA) glass filter into the environment, the glass fiber should be leached to lower its radioactive concentration to the clearance level. To derive an optimum method for the removal of uranium series from a HEPA glass fiber, five methods were applied in this study. That is, chemical leaching by a 4.0 M HNO 3 -0.1 M Ce(IV) solution, chemical leaching by a 5 wt% NaOH solution, chemical leaching by a 0.5 M H 2 O 2 -1.0 M Na 2 CO 3 solution, chemical consecutive chemical leaching by a 4.0 M HNO 3 solution, and repeated chemical leaching by a 4.0 M HNO 3 solution were used to remove the uranium series. The residual radioactivity concentrations of 238 U, 235 U, 226 Ra, and 234 Th in glass after leaching for 5 h by the 4.0 M HNO 3 -0.1 M Ce(IV) solution were 2.1, 0.3, 1.1, and 1.2 Bq/g. The residual radioactivity concentrations of 238 U, 235 U, 226 Ra, and 234 Th in glass after leaching for 36 h by 4.0 M HNO 3 -0.1 M Ce(IV) solution were 76.9, 3.4, 63.7, and 71.9 Bq/g. The residual radioactivity concentrations of 238 U, 235 U, 226 Ra, and 234 Th in glass after leaching for 8 h by a 0.5 M H 2 O 2 -1.0 M Na 2 CO 3 solution were 8.9, 0.0, 1.91, and 6.4 Bq/g. The residual radioactivity concentrations of 238 U, 235 U, 226 Ra, and 234 Th in glass after consecutive leaching for 8 h by the 4.0 M HNO 3 solution were 2.08, 0.12, 1.55, and 2.0 Bq/g. The residual radioactivity concentrations of 238 U, 235 U, 226 Ra, and 234 Th in glass after three repetitions of leaching for 3 h by the 4.0 M HNO 3 solution were 0.02, 0.02, 0.29, and 0.26 Bq/g. Meanwhile, the removal efficiencies of 238 U, 235 U, 226 Ra, and 234 Th from the waste solution after its precipitation-filtration treatment with NaOH and alum for reuse of the 4.0 M HNO 3 waste solution were 100, 100, 93.3, and 100%. (author)

Recovery of uranium values

International Nuclear Information System (INIS)

Rowden, G.A.

1982-01-01

A process is provided for the recovery of uranium from an organic extractant phase containing an amine. The extractant phase is contacted in a number of mixing stages with an acidic aqueous stripping phase containing sulphate ions, and the phases are passed together through a series of mixing stages while maintaining a dispersion of droplets of one phase in the other. Uranium is precipitated from the final stage by raising the pH. An apparatus having several mixing chambers is described

The acid aging as alternative process for uranium recovery from silicated ores

International Nuclear Information System (INIS)

Cipriani, M.; Della Testa, A.

1984-01-01

The influence of different variables on the extraction uranium efficiency and on the silicate solubility by means of acid aging is studied. The variables studied in bench scale were: acid/ore, oxidizing/ore and liquid/solid relationships; reaction time; temperature and recovery time. The results are discussed and compared with the ones of continuous operation of a semi-pilot plant. A flowsheet of the industrial process application is presented. (M.A.C.) [pt

Application of the 226Ra-230Th-234U and 227Ac-231Pa-235U radiochronometers to uranium certified reference materials

International Nuclear Information System (INIS)

Rolison, J.M.; Treinen, K.C.; McHugh, K.C.; Gaffney, A.M.; Williams, R.W.

2017-01-01

Uranium certified reference materials (CRM) issued by New Brunswick Laboratory were subjected to dating using four independent uranium-series radiochronometers. In all cases, there was acceptable agreement between the model ages calculated using the 231 Pa- 235 U, 230 Th- 234 U, 227 Ac- 235 U or 226 Ra- 234 U radiochronometers and either the certified 230 Th- 234 U model date (CRM 125-A and CRM U630), or the known purification date (CRM U050 and CRM U100). The agreement between the four independent radiochronometers establishes these uranium certified reference materials as ideal informal standards for validating dating techniques utilized in nuclear forensic investigations in the absence of standards with certified model ages for multiple radiochronometers. (author)

Uranium mine ventilation

International Nuclear Information System (INIS)

Katam, K.; Sudarsono

1982-01-01

Uranium mine ventilation system aimed basically to control and decreasing the air radioactivity in mine caused by the radon emanating from uranium ore. The control and decreasing the air ''age'' in mine, with adding the air consumption volume, increasing the air rate consumption, closing the mine-out area; using closed drainage system. Air consumption should be 60m 3 /minute for each 9m 2 uranium ore surfaces with ventilation rate of 15m/minute. (author)

Different periods of uranium and thorium occurrence in Madagascar (1960)

International Nuclear Information System (INIS)

Moreau, M.

1960-01-01

In Madagascar, the first typical occurrences of thorium and uranium are about 500 million years old. Previously thorium and uranium were rather concentrated in the granitic and charnockitic zones, chiefly in minerals such as monazite, apatite and zircon. At the end of the Precambrian period, metasomatic granites occur especially in the anticlinal series (Andriba orthite granite). The granitization is followed by the formation of the main pegmatitic areas in the Island with Th-U niobotantalates, uraninite and beryl. The pegmatites are well developed in the synclinal series with a poor migmatization or no migmatization at all. In the same time a large uranium and thorium province with uranothorianite deposits appears within the calcomagnesian series of the Southern part of Madagascar. Later, large amounts of monazite were carried down to the detritic Karroo sediments during tile erosion of the metamorphic precambrian rocks. Monazite has been concentrated again by frequent marine incursions, till the present time. In the medium Karroo, near Folakara, uranium minerals occur in direct relation with carbonaceous material. Finally we must note the uranium occurrence in the pleistocene carbonaceous shales of Antsirabe basin, in contact with crystalline rocks. (author) [fr

The fracture mechanism of uranium-niobium alloys near hypoeutectoid composition aged at low temperature

International Nuclear Information System (INIS)

Wang Xiaoying; Ren Dapeng; Yang Jianxiong; Jiang Guifen

2006-01-01

The microstructures and the crack propagation of uranium-niobium alloys near hypoeutectoid composition aged at temperature 200 degree C for 2 hours during a tension was investigated by means of in situ tension tests using TEM. The results show that the twinning planes inside and between the martensite laths move and merge, and then disintegrate in uranium-niobium alloys with monoclinic α structure during the tension. The crack propagation can be described as follows. Under the tension, the thinning zone which is locally plastically deformed emerges in the front of the crack tip. After the process of nucleation, growth and conjunction, the microvoids connect with the main crack, which results in the fracture. Neither of emission, propagation and movement of dislocation was observed during the tension. (authors)

Study on geochronology and uranium source of sandstone-type uranium deposit in Dongsheng area

International Nuclear Information System (INIS)

Liu Haibin; Xia Yuliang; Tian Shifeng

2007-01-01

This paper studied the geochronology of sandstone-type uranium deposit in the Dongsheng area of Ordos Basin. In eastern segment, ages of mineralization at the wing of the ore-roll are found to be 120 ± 5 Ma and 80 ± 5 Ma, and at the front of the ore-roll are 20 ± 2 Ma and 8 ± 1 Ma; While in middle segment, ages of mineralization are 124 ± 6 Ma and 80 ± 5 Ma. This means that the main mineralization in Dongsheng area were formed at early Jurassic and late Cretaceous, and correspondent to the time of structure uplift. Mineralization of roll-front (rich ore) which formed in Miocene and Pliocene may related to tectonic-thermal event taken place at that time and reformed the early mineralization in this area. The isochron line age of sample with uranium grade 0 ) in the sandbody is 24.64 x 10 -6 also shows the uranium pre-concentration in the strata. The even value of ΔU of rocks in Zhiluo formation is -70.2%, this shows that non-mineralized rocks have migrated uranium and acted as important metallogenic uranium sources. (authors)

The quaternary evolution of the British south pennines from uranium series and palaeomagnetic data

International Nuclear Information System (INIS)

Rowe, P.; Austin, T.; Atkinson, T.

1988-01-01

Analyses of uranium and thorium isotopes in calcite samples from thick flowstones within a high level relict cave remnant (Elder Bush Cave) indicated that the formations were beyond the range of the uranium-thorium dating technique (350 ka). 234 U/ 238 U isotope activity ratios approached unity, suggesting that the flowstones may have formed a considerable time before 350 ka. Palaeomagnetic samples taken from cores drilled through the flowstones showed the presence of both normally and reversely magnetized calcite. In some cases reversely magnetized layers overlie normally magnetized layers. This evidence, taken in conjunction with the uranium isotope data, is interpreted as indicating an Olduvai age (1.66-1.87 Ma) for some of the flowstone horizons. It is suggested that the cave became vadose by or soon after 2.0 MA. The position of the cave near the valley rim enables an estimate to be made of the maximum rate at which the present valley has been excavated. This is calculated to be 5.5 cm/ka. Remnants of old valley floors preserved within the existing valley suggest that downcutting has been a continuous process. Flowstone from a cave on one of the lower valley floor remnants (Darfur Ridge Cave) has been dated to 284 +34/-27ka allowing a maximum downcutting rate since that time of 11.2 cm/ka. The proximity of Elder Bush Cave to the valley crest suggests that its abandonment marked the onset of the incision of the present system of dales that characterize the English Peak District, presumably initiated by epeirogenic uplift or tilting. (Author)

Chemical thermodynamics of uranium

International Nuclear Information System (INIS)

Grenthe, I.; Fuger, J.; Lemire, R.J.; Muller, A.B.; Nguyen-Trung Cregu, C.; Wanner, H.

1992-01-01

A comprehensive overview on the chemical thermodynamics of those elements that are of particular importance in the safety assessment of radioactive waste disposal systems is provided. This is the first volume in a series of critical reviews to be published on this subject. The book provides an extensive compilation of chemical thermodynamic data for uranium. A description of procedures for activity corrections and uncertainty estimates is given. A critical discussion of data needed for nuclear waste management assessments, including areas where significant gaps of knowledge exist is presented. A detailed inventory of chemical thermodynamic data for inorganic compounds and complexes of uranium is listed. Data and their uncertainty limits are recommended for 74 aqueous complexes and 199 solid and 31 gaseous compounds containing uranium, and on 52 aqueous and 17 solid auxiliary species containing no uranium. The data are internally consistent and compatible with the CODATA Key Values. The book contains a detailed discussion of procedures used for activity factor corrections in aqueous solution, as well as including methods for making uncertainty estimates. The recommended data have been prepared for use in environmental geochemistry. Containing contributions written by experts the chapters cover various subject areas such a s: oxide and hydroxide compounds and complexes, the uranium nitrides, the solid uranium nitrates and the arsenic-containing uranium compounds, uranates, procedures for consistent estimation of entropies, gaseous and solid uranium halides, gaseous uranium oxides, solid phosphorous-containing uranium compounds, alkali metal uranates, uncertainties, standards and conventions, aqueous complexes, uranium minerals dealing with solubility products and ionic strength corrections. The book is intended for nuclear research establishments and consulting firms dealing with uranium mining and nuclear waste disposal, as well as academic and research institutes

Thermal stress relieving of dilute uranium alloys

International Nuclear Information System (INIS)

Eckelmeyer, K.H.

1980-01-01

The kinetics of thermal stress relieving of uranium - 2.3 wt. % niobium, uranium - 2.0 wt. % molybdenum, and uranium - 0.75 wt. % titanium are reported and discussed. Two temperature regimes of stress relieving are observed. In the low temperature regime (T 0 C) the process appears to be controlled by an athermal microplasticity mechanism which can be completely suppressed by prior age hardening. In the high temperature regime (300 0 C 0 C) the process appears to be controlled by a classical diffusional creep mechanism which is strongly dependent on temperature and time. Stress relieving is accelerated in cases where it occurs simultaneously with age hardening. The potential danger of residual stress induced stress corrosion cracking of uranium alloys is discussed. It is shown that the residual stress relief which accompanies age hardening of uranium - 0.75% titanium more than compensates for the reduction in K/sub ISCC/ caused by aging. As a result, age hardening actually decreases the susceptibility of this alloy to residual stress induced stress corrosion cracking

Advances in Airborne and Ground Geophysical Methods for Uranium Exploration

International Nuclear Information System (INIS)

2013-01-01

One of the IAEA's statutory objectives is to 'seek to accelerate and enlarge the contribution of atomic energy to peace, health and prosperity throughout the world'. One way this objective is achieved is through the publication of a range of technical series. Two of these are the IAEA Nuclear Energy Series and the IAEA Safety Standards Series. According to Article III.A.6 of the IAEA Statute, the safety standards establish 'standards of safety for protection of health and minimization of danger to life and property.' The safety standards include the Safety Fundamentals, Safety Requirements and Safety Guides. These standards are written primarily in a regulatory style, and are binding on the IAEA for its own programmes. The principal users are the regulatory bodies in Member States and other national authorities. The IAEA Nuclear Energy Series comprises reports designed to encourage and assist R and D on, and application of, nuclear energy for peaceful uses. This includes practical examples to be used by owners and operators of utilities in Member States, implementing organizations, academia, and government officials, among others. This information is presented in guides, reports on technology status and advances, and best practices for peaceful uses of nuclear energy based on inputs from international experts. The IAEA Nuclear Energy Series complements the IAEA Safety Standards Series. According to current estimates, after 2050 available resources and cumulative uranium demand are expected to be balanced. Recent annual uranium production constitutes 65-75% of annual nuclear energy uranium requirements worldwide. With typical timeframes of between 15 and 40 years from the commencement of uranium exploration activities until uranium production, together with increasingly favourable uranium prices, many countries have seen a rise in uranium exploration activities since 2005. This experience and assessment of global energy needs support continued uranium exploration

Age estimates for the late quaternary high sea-stands

Science.gov (United States)

Smart, Peter L.; Richards, David A.

A database of more than 300 published alpha-counted uranium-series ages has been compiled for coral reef terraces formed by Late Pleistocene high sea-stands. The database was screened to eliminate unreliable age estimates ( {230Th }/{232Th } 5%) and those without quoted without quoted errors, and a distributed error frequency curve was produced. This curve can be considered as a finite mixture model comprising k component normal distributions each with a weighting α. By using an expectation maximising algorithm, the mean and standard deviation of the component distributions, each corresponding to a high sea level event, were estimated. Eight high sea-stands with mean and standard deviations of 129.0 ± 33.0, 123.0 ± 13.0, 102.5 ± 2.0, 81.5 ± 5.0, 61.5 ± 6.0, 50.0 ± 1.0, 40.5 ± 5.0 and 33.0 ± 2.5 ka were resolved. The standard deviations are generally larger than the values quoted for individual age estimates. Whilst this may be due to diagenetic effects, especially for the older corals, it is argued that in many cases geological evidence clearly indicates that the high stands are multiple events, often not resolvable at sites with low rates of uplift. The uranium-series dated coral-reef terrace chronology shows good agreement with independent chronologies derived for Antarctic ice cores, although the resolution for the latter is better. Agreement with orbitally-tuned deep-sea core records is also good, but it is argued that Isotope Stage 5e is not a single event, as recorded in the cores, but a multiple event spanning some 12 ka. The much earlier age for Isotope Stage 5e given by Winograd et al. (1988) is not supported by the coral reef data, but further mass-spectrometric uranium-series dating is needed to permit better chronological resolution.

Characterization of low concentration uranium glass working materials

Energy Technology Data Exchange (ETDEWEB)

Eppich, G. R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Wimpenny, J. B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Leever, M. E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Knight, K. B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Hutcheon, I. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Ryerson, F. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2016-03-22

A series of uranium-doped silicate glasses were created at (Lawrence Livermore National Laboratory) LLNL, to be used as working reference material analogs for low uranium concentration research. Specifically, the aim of this effort was the generation of well-characterized glasses spanning a range of concentrations and compositions, and of sufficient homogeneity in uranium concentration and isotopic composition, for instrumentation research and development purposes. While the glasses produced here are not intended to replace or become standard materials for uranium concentration or uranium isotopic composition, it is hoped that they will help fill a current gap, providing low-level uranium glasses sufficient for methods development and method comparisons within the limitations of the produced glass suite. Glasses are available for research use by request.

Synthesis, structure, spectroscopy and redox energetics of a series of uranium(4) mixed-ligand metallocene complexes

Energy Technology Data Exchange (ETDEWEB)

Thomson, R.K.; Scott, B.L.; Morris, D.E.; Kiplinger, J.L. [Los Alamos National Laboratory, Los Alamos, NM (United States)

2010-06-15

A series of uranium(IV) mixed-ligand amide-halide/pseudo-halide complexes (C{sub 5}Me{sub 5}){sub 2}U[N(SiMe{sub 3}){sub 2}](X) (X = F (1), Cl (2), Br (3), I (4), N{sub 3} (5), NCO (6)), (C{sub 5}Me{sub 5}){sub 2}U(NPh{sub 2})(X) (X = Cl (7), N{sub 3} (8)), and (C{sub 5}Me{sub 5}){sub 2}U[N(Ph)(SiMe{sub 3})](X) (X Cl (9), N{sub 3} (10)) have been prepared by one electron oxidation of the corresponding uranium(III) amide precursors using either copper halides, silver iso-cyanate, or triphenylphosphine gold(I)azide. Agostic U---H-C interactions and {eta}{sub 3}-(N,C,C') coordination are observed for these complexes in both the solid-state and solution. There is a linear correlation between the chemical shift values of the C{sub 5}Me{sub 5} ligand protons in the {sup 1}H NMR spectra and the U(IV)/U(III) reduction potentials of the (C{sub 5}Me{sub 5}){sub 2}U[N(SiMe{sub 3}){sub 2}](X) complexes, suggesting that there is a common origin, that is overall {sigma}-/{pi}-donation from the ancillary (X) ligand to the metal, contributing to both observables. Optical spectroscopy of the series of complexes 1-6 is dominated by the (C{sub 5}Me{sub 5}){sub 2}U[N(SiMe{sub 3}){sub 2}] core, with small variations derived from the identity of the halide/pseudo-halide. The considerable {pi}-donating ability of the fluoride ligand is reflected in both the electrochemistry and UV-visible-NIR spectroscopic behavior of the fluoride complex (C{sub 5}Me{sub 5}){sub 2}U[N(SiMe{sub 3}){sub 2}](F) (1). The syntheses of the new trivalent uranium amide complex, (C{sub 5}Me{sub 5}){sub 2}U[N(Ph)(SiMe{sub 3})](THF), and the two new weakly-coordinating electrolytes, [Pr{sub 4}N][B{l_brace}3,5-(CF{sub 3}){sub 2}C{sub 6}H{sub 3{r_brace}4}] and [Pr{sub 4}N][B(C{sub 6}F{sub 5}){sub 4}], are also reported. (authors)

Dietary intake and body content of natural uranium

International Nuclear Information System (INIS)

Anon.

1984-01-01

The members of the uranium series found in the body that arise primarily from dietary intake are 238 U, 234 U, 226 Ra and 210 Pb. Lead 210, the predominant series radionuclide in the body, decays to the alpha emitter 210 Po, while the others are alpha emitters themselves. While 210 Pb primarily enters the body through diet, inhalation must also be considered, especially in smokers. The primary site of deposition for these nuclides is the skeleton and the dose to bone is the critical factor. In this section, the average background, elevated natural and enhanced dietary intakes of the uranium series radionuclides are discussed. Human skeletal levels and consequent alpha doses are summarized

Irradiation Stability of Uranium Alloys at High Exposures

International Nuclear Information System (INIS)

McDonell, W.R.

2001-01-01

Postirradiation examinations were begun of a series of unrestrained dilute uranium alloy specimens irradiated to exposures up to 13,000 MWD/T in NaK-containing stainless steel capsules. This test, part of a program of development of uranium metal fuels for desalination and power reactors sponsored by the Division of Reactor Development and Technology, has the objective of defining the temperature and exposure limits of swelling resistance of the alloyed uranium. This paper discusses those test results

Uranium extraction technology

International Nuclear Information System (INIS)

1993-01-01

In 1983 the Nuclear Energy Agency of the Organisation for Economic Co-operation and Development (OECD/NEA) and the IAEA jointly published a book on Uranium Extraction Technology. A primary objective of this report was to document the significant technological developments that took place during the 1970s. The purpose of this present publication is to update and expand the original book. It includes background information about the principle of the unit operations used in uranium ore processing and summarizes the current state of the art. The publication also seeks to preserve the technology and the operating 'know-how' developed over the past ten years. This publication is one of a series of Technical Reports on uranium ore processing that have been prepared by the Division of Nuclear Fuel Cycle and Waste Management at the IAEA. A complete list of these reports is included as an addendum. Refs, figs and tabs

Distribution of uranium series radionuclides in upland vegetation of northern Saskatchewan

International Nuclear Information System (INIS)

Sheard, J.W.

1986-01-01

Multivariate methods are used to explore patterns of accumulation of radionuclides and stable elements among 10 plant species at four localities in northern Saskatchewan. Principal components analysis and canonical correlation analysis of the radionuclides and stable elements showed that lead-210 and polonium-210 are correlated with crustal elements distributed in the atmoshpere and therefore are accumulated more abundantly by lichen and moss species than by vascular plants. Uranium showed a similar trend. Neither these radionuclides nor radium-226 showed strong correlations with other stable elements. The highest accumulation of uranium was in the Wollaston Lake region, especially for the nonvascular plants, where the soil levels are lowest. This tends to substantiate previous suggestions that uranium available for uptake by vascular plants is associated with groundwater rather than soil particles. Canonical variates analysis on radionuclide levels in vegetation by species group shows that trees, shrubs, lichens, and moss all have significantly different patterns of accumulation. The vascular and nonvascular groups are separated primarily by lead-210 and polonium- 210 accumulation. The trees and shrubs are separated by radium-226 levels. A similar analysis by locality showed significant differences in radionuclide accumulation by vegetation in all possible pairs of localities, except between the two Wollaston Lake localities. The largest distances were between regions and were based primarily on uranium accumulation in the nonvascular plants. Differences in radium-226 levels among the shrub species are responsible for the significant difference between the two localities in the Churchill River region

Uranium concentration in fossils

International Nuclear Information System (INIS)

Okano, J.; Uyeda, C.

1988-01-01

Recently it is known that fossil bones tend to accumulate uranium. The uranium concentration, C u in fossils has been measured so far by γ ray spectroscopy or by fission track method. The authors applied secondary ion mass spectrometry, SIMS, to detect the uranium in fossil samples. The purpose of this work is to investigate the possibility of semi-quantitative analyses of uranium in fossils, and to study the correlation between C u and the age of fossil bones. The further purpose of this work is to apply SIMS to measure the distribution of C u in fossil teeth

DYNAMIC PROPERTIES OF SHOCK LOADED THIN URANIUM FOILS

International Nuclear Information System (INIS)

Robbins, D.L.; Kelly, A.M.; Alexander, D.J.; Hanrahan, R.J.; Snow, R.C.; Gehr, R.J.; Rupp, Ted Dean; Sheffield, S.A.; Stahl, D.B.

2001-01-01

A series of spall experiments has been completed with thin depleted uranium targets, nominally 0.1 mm thick. The first set of uranium spall targets was cut and ground to final thickness from electro-refined, high-purity, cast uranium. The second set was rolled to final thickness from low purity uranium. The impactors for these experiments were laser-launched 0.05-mm thick copper flyers, 3 mm in diameter. Laser energies were varied to yield a range of flyer impact velocities. This resulted in varying degrees of damage to the uranium spall targets, from deformation to complete spall or separation at the higher velocities. Dynamic measurements of the uranium target free surface velocities were obtained with dual velocity interferometers. Uranium targets were recovered and sectioned after testing. Free surface velocity profiles were similar for the two types of uranium, but spall strengths (estimated from the magnitude of the pull-back signal) are higher for the high-purity cast uranium. Velocity profiles and microstructural evidence of spall from the sectioned uranium targets are presented.

Uranium-enriched granites in Sweden

International Nuclear Information System (INIS)

Wilson, M.R.; Aakerblom, G.

1980-01-01

Granites with uranium contents higher than normal occur in a variety of geological settings in the Swedish Precambrian, and represent a variety of granite types and ages. They may have been generated by the anatexis of continental crust or processes occurring at a much greater depth. They commonly show enrichment in F, Sn, W and/or Mo. Only in one case is an important uranium mineralization thought to be directly related to a uranium-enriched granite, while the majority of epigenetic uranium mineralizations with economic potential are related to hydrothermal processes in areas where the bedrock is regionally uranium-enhanced. (author)

Uranium enriched granites in Sweden

International Nuclear Information System (INIS)

Wilson, M.R.; Aakerblom, G.

1980-01-01

Granites with uranium contents higher than normal occur in a variety of geological settings in the Swedish Precambrian, and represent a variety of granite types and ages. They may have been generated by (1) the anatexis of continental crust (2) processes occurring at a much greater depth. They commonly show enrichement in F, Sn, W and/or Mo. Only in one case is an important uranium mineralization thought to be directly related to a uranium-enriched granite, while the majority of epigenetic uranium mineralizations with economic potential are related to hydrothermal processes in areas where the bedrock is regionally uranium-enhanced. (Authors)

Principle of natural and artificial radioactive series equivalency

International Nuclear Information System (INIS)

Vasilyeva, A.N.; Starkov, O.V.

2001-01-01

In the present paper one approach used under development of radioactive waste management conception is under consideration. This approach is based on the principle of natural and artificial radioactive series radiotoxic equivalency. The radioactivity of natural and artificial radioactive series has been calculated for 10 9 - years period. The toxicity evaluation for natural and artificial series has also been made. The correlation between natural radioactive series and their predecessors - actinides produced in thermal and fast reactors - has been considered. It has been shown that systematized reactor series data had great scientific significance and the principle of differential calculation of radiotoxicity was necessary to realize long-lived radioactive waste and uranium and thorium ore radiotoxicity equivalency conception. The calculations show that the execution of equivalency principle is possible for uranium series (4n+2, 4n+1). It is a problem for thorium. series. This principle is impracticable for neptunium series. (author)

Uranium. Suppl. Vol. C7

International Nuclear Information System (INIS)

Keim, R.; Keller, C.

1982-01-01

In this supplement volume C7 the nitrogen compounds of uranium-anides, imides, nitrides, nitrites, nitrates are dealt with. Whereas amides, imides and nitrates have only been of scientific interest up to now, uranium nitride and uranylnitrate are of great technological importance. Therefore the description of the chemical and physical characteristics of UN as a potential fuel for future reactors already comprises about 1/4 of this volume. Also the description of uranyl nitrate - as one of the most important commercial forms of uranium and because of its importance in the chemistry of nuclear fuel element reprocessing - comprises many pages. This is supplemented by further uranium nitrides, ternary and polynary nitrides, oxide nitrides, double nitrides of the various valence steps as well as nitrate complexes and ternary and quarternary systems containing uranyl nitrate. The radiation behaviour of UN, and its distribution (liquid/liquid, liquid solid) as well as the complex formation of the uranyl ion with nitrate are described in other volumes of the uranium series. (RB) [de

Uranium isotopic compositions of the crust and ocean: Age corrections, U budget and global extent of modern anoxia

Science.gov (United States)

Tissot, François L. H.; Dauphas, Nicolas

2015-10-01

the variability of the 238U/235U ratio on Pb-Pb and U-Pb ages and provide analytical formulas to calculate age corrections as a function of the age and isotopic composition of the sample. The crustal ratio may be used in calculation of Pb-Pb and U-Pb ages of continental crust rocks and minerals when the U isotopic composition is unknown. In cosmochemistry, the search for 247Cm (t1/2 = 15.6 Myr), an extinct short-lived radionuclide that decays into 235U, is important for understanding how r-process nuclides were synthesized in stars and learning about the astrophysical context of solar system formation (Chen and Wasserburg, 1981; Wasserburg et al., 1996; Nittler and Dauphas, 2006; Brennecka et al., 2010b; Tissot et al., 2015). In both terrestrial and extraterrestrial samples, variations in the 238U/235U ratio affect Pb-Pb ages (and depending on the analytical protocols, U-Pb ages). Therefore, samples dated by these techniques need to have their U isotopic compositions measured (Stirling et al., 2005, 2006; Weyer et al., 2008; Amelin et al., 2010; Brennecka et al., 2010b; Brennecka and Wadhwa, 2012; Connelly et al., 2012; Goldmann et al., 2015) or uncertainties on the U isotopic composition should be propagated into age calculations. In low temperature aqueous geochemistry, U isotopic fractionation between U4+ and U6+ (driven in part by nuclear field shift effects; Bigeleisen, 1996; Schauble, 2007; Abe et al., 2008), makes U isotopes potential tracers of paleoredox conditions (Montoya-Pino et al., 2010; Brennecka et al., 2011a; Kendall et al., 2013, 2015; Asael et al., 2013; Andersen et al., 2014; Dahl et al., 2014; Goto et al., 2014; Noordmann et al., 2015). The present paper aims at constraining some aspects of the global budget of uranium in the modern oceans using 238U/235U isotope variations, which involves characterizing the U isotopic composition of seawater and several reservoirs involved in the uranium oceanic budget. Uranium can exist in two oxidation states

REIMEP-22 inter-laboratory comparison. ''U Age Dating - determination of the production date of a uranium certified test sample''

Energy Technology Data Exchange (ETDEWEB)

Venchiarutti, Celia; Richter, Stephan; Jakopic, Rozle; Aregbe, Yetunde [European Commission, Joint Research Centre (JRC), Geel (Belgium). Institute for Reference Materials and Measurements (IRMM); Varga, Zsolt; Mayer, Klaus [European Commission, Joint Research Centre (JRC), Karlsruhe (Germany). Institute for Transuranium Elements (ITU)

2015-07-01

The REIMEP-22 inter-laboratory comparison aimed at determining the production date of a uranium certified test sample (i.e. the last chemical separation date of the material). Participants in REIMEP-22 on ''U Age Dating - Determination of the production date of a uranium certified test sample'' received one low-enriched 20 mg uranium sample for mass spectrometry measurements and/or one 50 mg uranium sample for a-spectrometry measurements, with an undisclosed value for the production date. They were asked to report the isotope amount ratios n({sup 230}Th)/n({sup 234}U) for the 20 mg uranium sample and/or the activity ratios A({sup 230}Th)/A({sup 234}U) for the 50 mg uranium sample in addition to the calculated production date of the certified test samples with its uncertainty. Reporting of the {sup 231}Pa/{sup 235}U ratio and the respective calculated production date was optional. Eleven laboratories reported results in REIMEP-22. Two of them reported results for both the 20 mg and 50 mg uranium certified test samples. The measurement capability of the participants was assessed against the independent REIMEP-22 reference value by means of z- and zeta-scores in compliance with ISO 13528:2005. Furthermore a performance assessment criterion for acceptable uncertainty was applied to evaluate the participants' results. In general, the REIMEP-22 participants' results were satisfactory. This confirms the analytical capabilities of laboratories to determine accurately the age of uranium materials with low amount of ingrown thorium (young certified test sample). The Joint Research Centre of the European Commission (EC-JRC) organised REIMEP-22 in parallel to the preparation and certification of a uranium reference material certified for the production date (IRMM-1000a and IRMM-1000b).

Evaluation of new geological reference materials for uranium-series measurements: Chinese Geological Standard Glasses (CGSG) and macusanite obsidian.

Science.gov (United States)

Denton, J S; Murrell, M T; Goldstein, S J; Nunn, A J; Amato, R S; Hinrichs, K A

2013-10-15

Recent advances in high-resolution, rapid, in situ microanalytical techniques present numerous opportunities for the analytical community, provided accurately characterized reference materials are available. Here, we present multicollector thermal ionization mass spectrometry (MC-TIMS) and multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) uranium and thorium concentration and isotopic data obtained by isotope dilution for a suite of newly available Chinese Geological Standard Glasses (CGSG) designed for microanalysis. These glasses exhibit a range of compositions including basalt, syenite, andesite, and a soil. Uranium concentrations for these glasses range from ∼2 to 14 μg g(-1), Th/U weight ratios range from ∼4 to 6, (234)U/(238)U activity ratios range from 0.93 to 1.02, and (230)Th/(238)U activity ratios range from 0.98 to 1.12. Uranium and thorium concentration and isotopic data are also presented for a rhyolitic obsidian from Macusani, SE Peru (macusanite). This glass can also be used as a rhyolitic reference material, has a very low Th/U weight ratio (around 0.077), and is approximately in (238)U-(234)U-(230)Th secular equilibrium. The U-Th concentration data agree with but are significantly more precise than those previously measured. U-Th concentration and isotopic data agree within estimated errors for the two measurement techniques, providing validation of the two methods. The large (238)U-(234)U-(230)Th disequilibria for some of the glasses, along with the wide range in their chemical compositions and Th/U ratios should provide useful reference points for the U-series analytical community.

The Oklo natural nuclear reactors: neutron parameters, age and duration of the reactions, uranium and fission products migrations

International Nuclear Information System (INIS)

Ruffenach, J.-C.

1979-09-01

Mass spectrometry and isotopic dilution technique are used in order to carry out, on various samples from the fossil nuclear reactors at Oklo, Gabon, isotopic and chemical analyses of some particular elements involved in the nuclear reactions: uranium, lead, bismuth, thorium, rare gases (krypton, xenon), rare earths (neodymium, samarium, europium, gadolinium, dysprosium), ruthenium and palladium. Interpretations of these analyses lead to the determination of many neutron parameters such as the neutron fluence received by the samples, the spectrum index, the conversion coefficient, and also the percentages of fissions due to uranium-238 and plutonium-239 and the total number of fissions relative to uranium. All these results make it possible to determine the age of the nuclear reactions by measuring the amounts of fission rare earths formed, i.e. 1.97 billion years. This study brings some informations to the general problem of radioactive wastes storage in deep geological formations, the storage of uranium, plutonium and many fission products having been carried out naturally, and for about two billion years [fr

Uranium-lead age determinations on granitic rocks from the eastern Bushveld Complex

International Nuclear Information System (INIS)

Faurie, J.N.

1978-08-01

Uranium-lead age determinations were carried out on four types of granitic rocks from the eastern Bushveld Complex. The oldest rocks in the area are gneisses and felsites - 2604 plus minus 100 m.y. old - which form the centre of the Dennilton dome. The Rooiberg felsites could not be dated directly because of the absence of zircon, however a porphyritic granite sill, which shows intrusive relations with the Rooiberg felsites, was dated at 2090 plus minus 40 m.y., an age which can also be regarded as a minimum age for the Rooiberg felsites. No reliable age could be determined for the granophyres because of the large amount of lead-loss reflected in the zircon. The majority of zircons from these granophyres showed a peculiar hieroglyphic texture, a phenomena which has not yet been recorded in literature. The samples collected from the granites gave an age of 1950 plus minus 80 m.y. and thus form part of the Nebo Granite. Attempts have been made to obtain more concordant zircon ages throughout the present study. Although some success was achieved by analysing different size fractions of a zircon population, the non-magnetic fractions gave the most promising results [af

Sorption of uranium on rocks in anaerobic groundwater

International Nuclear Information System (INIS)

Hakanen, M.

1992-12-01

Spent nuclear fuel contains substantial amounts of long lived isotopes of actinoide elements, the most abundant of which is the oxide from uranium in the fuel matrix. The behaviour of uranium, also present in small concentrations in natural rocks and waters, is redox sensitive. The concentration controlling mechanisms in groundwaters of uranium are not well-known. In this work a series of laboratory experiments was made to study the redox and sorption behaviour of uranium under anaerobic conditions. The experiments indicated that a part of uranium(VI) was reduced to uranium(IV). The sorbed uranium was of mixed oxidation states. The redox potential of water was not an appropriate indicator of the U(IV)/U(VI) ratio. Spiking of the water with the U(IV) was followed by very strong sorption. The derived lower limit (conservative) and the realistic mass distribution ratios (R d ) for U(IV) are 0.7 m 3 /kg and 3.5 m 3 /kg. (orig.)

Report on the second uranium-series intercomparison project workshop, Harwell, 23 to 24, June 1980

International Nuclear Information System (INIS)

Ivanovich, M.; Warchal, R.M.

1981-03-01

The second Uranium-series Intercomparison Project Workshop was held on June 23 and 24, 1980 at Harwell. The aim of the Workshop was to analyse the results of Phase III of the Project and to define the future aims of the Project, if any. This report is an account of the matters raised and discussed during the two day workshop. A detailed report of a statistical analysis of USIP results - Phases I, II, and III is included. A final report submitted to USIP by CBNM, Euratom Laboratory, Geel, on the determination of the alpha activity ratio 228 Th/ 232 U in the Harwell spike solution used in USIP Phase III is reproduced in full. An account of an investigation into suitability of a limestone specimen for a geologic standard carried out at Koeln University is also given. (author)

Capstone Depleted Uranium Aerosols: Generation and Characterization

Energy Technology Data Exchange (ETDEWEB)

Parkhurst, MaryAnn; Szrom, Fran; Guilmette, Ray; Holmes, Tom; Cheng, Yung-Sung; Kenoyer, Judson L.; Collins, John W.; Sanderson, T. Ellory; Fliszar, Richard W.; Gold, Kenneth; Beckman, John C.; Long, Julie

2004-10-19

In a study designed to provide an improved scientific basis for assessing possible health effects from inhaling depleted uranium (DU) aerosols, a series of DU penetrators was fired at an Abrams tank and a Bradley fighting vehicle. A robust sampling system was designed to collect aerosols in this difficult environment and continuously monitor the sampler flow rates. Aerosols collected were analyzed for uranium concentration and particle size distribution as a function of time. They were also analyzed for uranium oxide phases, particle morphology, and dissolution in vitro. The resulting data provide input useful in human health risk assessments.

Uranium in a recent phosphorite formation process

Energy Technology Data Exchange (ETDEWEB)

Baturin, G N; Dubinchuk, V I; Kochenov, A V

1986-01-01

Uranium behaviour in the process of nowadays phosphorite formation in the sediments of Namibia shelf is considered. The material collected during the 3-d trip of the research vessel ''Akademik Kurchatov'' and 26-th trip of the research vessel ''Mikhail Lomonosov'' is used. The samples from three geological stations 2046, 2047 and 2048 from the depths of 78-87 m have been investigated. Each sample (mass from 0.2 to 0.3 kg) is composed of several samples representing unified genetic series: holocene diatomic silts enclosing phosphorites - phosphatized silts - phosphorite concretions. Uranium has been determined by the X-ray spectral method; phosphorus, organic carbon and other components - by the chemical analysis. Uranium forms investigated by the combination of methods of electron microscopy, microdiffraction, microradioautography and microsounding. Uranium content in nowadays phosphorites at the shelf is 3-106 g/t. Uranium accumulation in phosphorites at the initial stages of their formation is controlled by its content in host sediments. In the course of litification of diagenetic phosphate concretions the uranium content in them varies from 40 to 80 g/t. The uranium concentration process in phosphorites is accompanied by formation of independent mineral phases of uranium oxide and ningyoite type.

Genetic types of uranium deposits of Ukraine

International Nuclear Information System (INIS)

Anysimov, V.A.

1997-01-01

There are three genetic classes of uranium deposits in Ukraine. Eight types of uranium deposits are described with reference to their genesis, age and geological position. The attributes of uranium concentration in Precambrian and Proterozoic periods of activization are shown. (author). 1 fig., 1 tab

The evolutionary characteristics and study of uranium mineralization conditions of early precambrian basement and old granitoids in Northern Hebei province of China

International Nuclear Information System (INIS)

Xia Yuliang; Rong Jiashu; Lin Jinrong; Zheng Maogong; Wen Xiyuan

1993-05-01

Based on the systematic studies of petrology, geochemistry and isotope geochronology, the Early Precambrian metamorphic complex in Northern Hebei province of China can be divided into three different series, i.e. granulite series, khondalite series and amphibolitic-felsic rock series. The so called 'magmatic granitoids' in that area are actually some magmagranites with different ages and different geneses, and they are not formed by migmatization. Up to now, the discovered Huaian complex which was formed in 3.5 Ga ago is the oldest nuclear area in the northern margin of North-China Platform. The granulite series, khondalite series and amphibolitic-felsic rock series belong to Early Archaean (>3.0 +- 0.1 Ga), Middle Archaean (>2.7 +- 0.1 Ga) and Later Archaean (>2.4 +- 0.1 Ga) respectively. The geological time scale of the Early Precambrian for Northern Hebei Province has been built. According to the synthetic analyses of various factors there is no prospect of uranium mineralization in the ancient terrain. However, the Mesozoic volcanic basins covering over the Hercynian Period granites would be main goal for looking for large uranium deposits in north part in that area

Utilization of BSS-Safety Series 115 in facilities for mining ore with uranium and thorium associated to it

International Nuclear Information System (INIS)

Matta, Luiz Ernesto S. de C.; Ferreira, Paulo R. Rocha; Mouco, Charles D. do C.L.

1999-01-01

During the year of 1995, the Brazilian Nuclear Energy Commission, started a investigation program called Mining Project. The main objective of this program was to create a integrated study of environmental and occupational conditions of mining ores with uranium and thorium associated to it. Several technical visits were done at four different types of mines: coal, phosphate, niobium and gold. This work presents the area monitoring results obtained by the occupational radiation protection group. The data found in these inspections were compared to limits established by national rules. A special assessment of the data obtained was done for a future adoption of the BSS-Safety Series 115 recommendations. (author)

Uranium-series radionuclides in native fruits and vegetables of northern Australia

International Nuclear Information System (INIS)

Ryan, B.; Martin, P.; Iles, M.

2005-01-01

Wild fruits and vegetables play an important part in a traditional Aboriginal diet in northern Australia. Radionuclide uptake by these foods is important for radiological impact assessment of uranium mining operations in the region, particularly after minesite rehabilitation. Data are presented for concentrations in several fruits and root vegetables, and associated soils. In terms of radiological dose, 210 Po, 226 Ra and, to a lesser extent, 210 Pb were found to be of greater importance than the uranium and thorium isotopes. Other important factors that have emerged include food preparation and consumption habits of Aboriginal people which could potentially affect radionuclide intake estimates. (author)

Speciation and spectrophotometric determination of uranium in seawater

Directory of Open Access Journals (Sweden)

M. KONSTANTINOU

2004-06-01

Full Text Available A series of ion-exchange and extraction procedures for the separation of uranium from seawater samples and subsequent spectrophotometric determination of uranium in seawater by means of arsenazo(III is described. According to the measurements performed by means of traced samples at every stage of separation, the yield of the pre-analytical procedures is generally over 90% and the separation of uranium very selective. The mean uranium concentration in seawater samples collected from five different coastal areas in Cyprus was found to be 3.2 ± 0.2 & micro; g L-1. Uranium in seawater is stable in its hexavalent oxidation state and UO2 (CO334- is the predominant species under normal coastal conditions (pH ≥ 8, EH ≥ 0.35 mV, 1 atm and 0.03% CO2.

Granite-related hypothermal uranium mineralization in South China

International Nuclear Information System (INIS)

Liu, X.; Wu, J.; Pan, J.; Zhu, M.

2014-01-01

As one of the important geological types, granite-related uranium deposits account for about 29% of the total discovered natural uranium resources in China. Most of the granite-related uranium deposits located in Taoshan - Zhuguang uranium metallogenic belt, South China. In addition to the typical pitchblende vein-type uranium mineralization of epithermal metallogenic system, a new type of granite-related uranium mineralization with characteristics of hypothermal matallogenic system was discovered in South China by current studies. However, hypothermal is contact thermal to epithermal mineralization, and not the conventional intrusive high temperature mineralization. Hypothermal uranium mineralization is presented by disseminated uraninite or pitchblende stockwork in fissures in granites normally with extensive alkaline alteration. The high temperature mineral assemblage of uraninite associate with scheelite and tourmaline was identified in hypothermal uranium mineralization. Fluid inclusion studies on this type mineralization indicated the middle to high temperature (>250℃) mineralization with the mixing evidence of ore forming solution derived from deep level, and the boiling and mixing of ore forming solution are regarded as the dominant mineralization mechanism for the precipitating of uranium. In contrast to the mineralization ages of 67 Ma to 87 Ma for typical pitchblende vein mineralization of epithermal metallogenic system, the mineralization age is older than 100 Ma for hypothermal uranium mineralization in granite. In the Shituling deposit, Xiazhuang uranium ore field, uraninite and pitchblende micro veins with extensive potassic alteration, chloritization and sericitization are hosted in fissures of Indo-Chinese epoch granites with the uranium mineralization age of 130 Ma to 138 Ma with a mineralization temperature of 290℃ to 330℃ indicated. Other examples sharing the similar characters of hypothermal uranium mineralization have been recognized in

Exploration and uranium mining in Niger

International Nuclear Information System (INIS)

Moussa, M.

2014-01-01

Niger is a Sahelian country bordered by Algeria and Libya to the north, Mali and Burkina Faso to the west, Benin and Nigeria to the south and Chad to the east. Niger has approximately 17 million habitants in the last census (2013) and covers an area of 1.27 million km"2. Niger’s climate is very hot and dry (45-50°C in the hot season, 30°C in the winter), daily ranges of temperature vary from 20 to 30°C. There is a rainy season with light rain fall (40 mm) extending from June to September. Niger’s economy is centered on subsistence agriculture, animal husbandry and uranium production. Uranium exports accounted for 70% of the national export economy during the 1970s, but falling prices have caused the contribution from uranium to shrink substantially in recent years. Uranium ore deposits in the Niger Republic are located in the western part of the country, west of the Aïr Mountains. The Arlit site is located 250 km north of Agadez, and 1200 km north-west of Niamey, the capital of Niger. After the discovery of the first uranium occurrences in 1956, systematic exploration programmes were conducted between 1960 and 1968 along the western sedimentary margin of Aïr Mountains, in North Central Niger by French company CEA. These programmes led to the discovery of several uranium deposits including the Arlit and Akouta deposits which are presently being mined respectively by SOMAIR and Cominak. Further works by CEA and its 100% subsidiary COGEMA and other companies consisted basically in follow up of the different targets outlined by the above programmes. The rocks hosting the uranium mineralisation are commonly arenites of the Carboniferous age Guezouman and Tarat Formations. Some beds within the Tchirozerine Formation of Jurassic age and the Irhazer Formation of Cretaceous age also contain uranium. The depositional environment of these formations was fluvial to deltaic. Apparently uranium was leached from the basement. Tectonic, lithological and geochemical

U-Pb ages related to uranium mineralization of Lagoa Real, Bahia - Brazil: tectonic implications

Energy Technology Data Exchange (ETDEWEB)

Chaves, Alexandre O.; Rios, Francisco J.; Oliveira, Lucilia A.R.; Alves, James V.; Fuzikawa, Kazuo; Neves, Jose M.C.; Chaves, Adriana M.D.V.; Prates, Sonia P. [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)]. E-mail: aoc@cdtn.br; Tubrett, Michael [Memorial University of Newfoundland, NL (Canada). Inco Innovation Centre. MicroAnalysis Facility; Matos, Evando C. [Industrias Nucleares do Brasil S.A. (INB), Rio de Janeiro, RJ (Brazil)

2007-07-01

The uranium from Lagoa Real (Bahia/Brazil) is associated with syenitic magmatism (1904 {+-}44 Ma minimum age from upper intercept of zircon U-Pb discordia by LA-ICP-MS) belonging to a mafic/ felsic lithologic association linked to the final stages of 2.05-1.80 Ga Orosirian Orogeny, which acted in the Paramirim Block. These syenitic rocks are rich not only in albite, but also in U-rich titanite (source of uranium). In association with the development of the Orosirian ductile shear zones, the syenites were crystallized and deformed. The metamorphic reactions, which include intense recrystallization of magmatic minerals, led uraninite to precipitate (1868 {+-} 69 Ma; U-Pb by LA-ICP MS) under Redox control. A second population of uraninites was also generated by shear zones reactivation during 0.6-0.5 Ga Brasiliano Orogeny (605 {+-} 170 Ma; U-Pb by LA-ICP-MS). The geotectonic implications are: a) the importance of the Orosirian event in the Paramirim Block during paleoproterozoic Sao Francisco/Congo Craton edification and b) the influence of the Brasiliano event in the Paramirim Block during the West-Gondwana assembly processes, indicated by the 605 {+-} 170 Ma uraninite (second population) age and by the 483 {+-} 100 Ma lower intercept of the metamorphosed syenite U-Pb discordia. (author)

Sedimentary uranium deposits in France and French Union; Les gisements uraniferes dans les formations sedimentaires en France et dans l'Union francaise

Energy Technology Data Exchange (ETDEWEB)

Kervella, F [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1958-07-01

The author gives the actual state of our knowledge on uranium deposits found in recent years. Till now in precambrian formations only one important deposit has been found, at Mounana (Gabon) in a series of conglomeratic sandstones belonging to the 'Francevillien'. The observed mineralization is of the uranium-vanadium type. To the carboniferous formations corresponds in France a series of deposits, among which the most important ones are located at Saint-Hippolyte. Uranium as carburans, organic-bound complexes, is contained in lacustrine schists of Westphalian or lower Stephanian formations. A number of occurrences are also known in permo-triassic formations, particularly in the Vanoise Alps, in the Maritime Alps and in the Herault, where important occurrences have recently been found not far from Lodeve. The cretaceous and tertiary systems contain uranium deposits in phosphate rocks (Morocco, Senegal, Togo, Middle-Congo). Two sedimentary oligocene deposits are known in France. Lastly, the Vinaninkarena deposit in Madagascar, known for a long time, is the only important one reported in the quaternary series. (author) [French] L'auteur fait le point des connaissances acquises sur les gisements decouverts dans les formations sedimentaires en France et dans l'Union francaise au cours des dernieres annees. Les gisements sont classes selon l'age de la formation dans laquelle on les observe. Les terrains precambriens n'ont pour l'instant fourni qu'un seul gisement notable; situe a Mouana (Gabon). C'est en decembre 1956 que cet important gisement fut decouvert dans une serie de gres conglomeratiques appartenant au Francevillien. La mineralisation observee est du type vanadium-uranium. Au carbonifere correspond en France metropolitaine une serie de gisements d'interet variable. Les plus importants sont ceux de Saint-Hippolyte (Haut-Rhin) ou l'uranium est contenu dans des schistes lacustres du Westphalien ou du Stephanien inferieur. L'uranium n'y existe pas sous forme

U/Pb dating: brioverian age of the Erquy series (Armorican massif, France)

International Nuclear Information System (INIS)

Cocherie, A.; Chantraine, J.; Egal, E.; Fanning, C.M.; Dabard, M.P.; Paris, F.; Le Herisse, A.

2001-01-01

New U/Pb analyses obtained with a high-resolution ion microprobe (SHRIMP) fix an age of 608 ± 7 Ma for spilites of the Erquy series, in Cadomian rocks of the Armorican massif, France. This Neo-proterozoic age re-integrates this unit into the Brioverian, the age it was initially assigned to. A Rb/sr whole-rock dating in the 1970's had undermined the regional Cadomian model, by suggesting an Ordovician age for these rocks; this was apparently further supported by the discovery of organic remains, interpreted as Paleozoic micro-fossils. The reassessment of this paleontologic attribution and the new isotope dating are a final confirmation of the age of this series. (authors)

Typomorphism and isomorphism of uranium hydroxides of the woelsendorfite group

International Nuclear Information System (INIS)

Belova, L.N.; Ryzhov, V.I.; Fedorov, O.V.; Lyubomilova, G.V.

1985-01-01

In oxidation zone of uranium deposit uranium hydroxides of the wolsendorfite group: calcuranoite, bauranoite, wolsendorfite and their varieties are studied. Chemical and microprobe analyses are carried out. It is established, that the minerals are encountered in the form of two generations. Early generation forms partial or complete pseudomorphosis over rich contrast pitchblende ores. The late one is encountered in the form of redeposited crystal aggregates in calcite-pitchblende streaks. Study in details of chemical composition of the group minerals permitted to establish the existence of a continuous isomorphous series with ultimate members calcuranoite and wolsendorfite with regular change in chemical and physical properties within the series. Existence of bauranoite-calcuranoite and bauranoite-wolsendorfite isomorphous series is assumed

Uranium concentrations in fossils measured by SIMS

International Nuclear Information System (INIS)

Uyeda, Chiaki; Okano, Jun

1988-01-01

Semiquantitative analyses of uranium in fossil bones and teeth were carried out by SIMS. The results show a tendency that uranium concentrations in the fossils increase with the ages of the fossils. It is noticed that fossil bones and teeth having uranium concentration of more than several hundred ppm are not rare. (author)

Ligand influences on properties of uranium coordination complexes. Structure, reactivity, and spectroscopy

International Nuclear Information System (INIS)

Kosog, Boris

2012-01-01

In this thesis several different aspects of uranium chemistry are presented. It was shown that terminal uranium(V) oxo and imido complexes [(( R ArO) 3 tacn)U V (O)] and [(( R ArO) 3 tacn)U V (NSiMe 3 )] (R = t Bu, Ad) can be oxidized by silver(I) hexafluoro-antimonate to the uranium(VI) oxo and imido complexes [(( R ArO) 3 tacn)U VI (O)]SbF 6 and [(( R ArO) 3 tacn)U VI (NSiMe 3 )]SbF 6 . While for the t Bu-derivative of the oxo complex an equatorial coordination is observed due to stabilization by the inverse trans-influence, normal axial coordination is observed for the Ad-derivative and both imido complexes. The inverse trans-influence was thus proven to be a key factor for the coordination mode of a terminal ligand on high valent uranium complexes. L III XANES was shown to be a great tool for the determination of oxidation states of uranium complexes. Therefore, a series of uranium complexes in all stable oxidation states for uranium, +III to +VI was prepared, and their spectra analyzed. All compounds bear only O-donor ligands in addition to the chlating trisaryloxide-tacn-ligand. A separation of 1.5 to 3 eV in the white line energy is observed between the different oxidation states. This series can be used as reference for compounds, where oxidation state assignment is not obvious, such as a ketyl radical complex [(( t-Bu Ar)O 3 tacn)U(O-C( t-Bu Ph) 2 .- )]. For this complex, the oxidation state of +IV could be assigned. Moreover, a series of isostructural uranium(IV) complexes was prepared. The influence of different ligands according to the spectrochemical series on the electronic and magnetic properties could be shown using UV/vis/NIR spectroscopy and variable temperature SQUID measurements. Calculations of uranium L III XANES spectra show a variation in the shape of the spectra and thus high resolution PFY-XANES would be a great tool to determine the electronic influence of these different axial ligands. Using the single N-anchored ligand system, the first

International Uranium Resources Evaluation Project (IUREP) orientation phase mission report: Cameroon. Draft

International Nuclear Information System (INIS)

Trey, Michel de; Leney, George W.

1983-05-01

Geology Branch with mapping and exploration services. Most of CAMEROON is underlain by Precambrian granites , anatexites, migmatites, gneisses, and schists. The NTEM complex in the south is Archean age. Most other areas are probably Lower Proterozoic, with some Middle Proterozoic inliers of the LOM, POLI, and MBALMAYO-BENGBIS, and the DJA series in the southeast. The DJA tillite is probably Upper Proterozoic. There are small remnant basins of Paleozoic volcanics, and larger basins and grabens of Middle-Upper Cretaceous. Tertiary rocks are present in the Coastal basins and the southeast. The Lake Chad depression is covered with Quaternary sands. All of the older rocks except the NTEM complex and the DJA series are within the Panafrican Mobile Belt. The border faults of the Cretaceous BENOUE graben are throughgoing crustal features. Tertiary intrusives and plateau basalts are found along the 'LINE OF CAMEROON', and volcanism has continued to present. Uranium exploration from 1950 to present has produced mostly negative results. Only one important prospect has been found at GOBLE-KITONGO, and has been the subject of repeated exploration from 195 8 to present. An enriched zone in syenite at LOLODORF is also under investigation. Anomalies on an airborne survey of the DJA series are being checked for mineralization similar to the FRANCEVILLIAN of GABON. Total expenditures that may be assigned to uranium are on the order of $10 million (U.S.). There are no uranium ore reserves or reasonably assured resources in CAMEROON. Speculative resources of 10,000 tonnes have been assigned to the LOLODORT syenite, and 5000 tonnes to the GOBLE-KITONGO prospect and Paleozoic volcanics at $130/kg. (U.S.). Favorable areas are the DJA series, syenites of the Panafrican granite and 'granites ultimes', Mesozoic-Cenozoic basins (especially DOUALA), LOM and MBALMAYO-BENGBIS series, POLI-MAROUA, and Lower Proterozoic/Archean gneiss and granite. Recommendations have been made for topical studies of

Thermal stress relieving of dilute uranium alloys

International Nuclear Information System (INIS)

Eckelmeyer, K.H.

1981-01-01

The kinetics of thermal stress relieving of uranium - 2.3 wt % niobium, uranium - 2.0 wt % molybdenum, and uranium - 0.75 wt % titanium are reported and discussed. Two temperature regimes of stress relieving are observed. In the low temperature regime (T 0 C) the process appears to be controlled by an athermal microplasticity mechanism which can be completely suppressed by prior age hardening. In the high temperature regime (300 0 C 0 C) the process appears to be controlled by a classical diffusional creep mechanism which is strongly dependent on temperature and time. Stress relieving is accelerated in cases where it occurs simultaneously with age hardening. The potential danger of residual stress induced stress corrosion cracking of uranium alloys is discussed

Impact of aging on the solid phase chemical fractionation of uranium in soil

International Nuclear Information System (INIS)

Rout, Sabyasachi; Ajay Kumar; Ravi, P.M.; Tripathi, R.M.

2015-01-01

A distinction should be made between persistence of total uranium (U) in soil and persistence of its bioavailable forms. As U age in soil, there is a change in bioavailability. The aging process is partially reversible if environmental parameters change, although a portion of the U ion will be securely entrapped in the soil particle lattice and not available to be re-solubilized. A study was carried out to reveals the impact of aging on chemical fractionation of U in amended soils from three different origin (Soil A: Metamorphic; Soil B: Sedimentary and Soil C: Ingenious basalt). For the study, 5g from each soil were amended with the 50 ml of water containing 100.0 mg/L of U in a falcon tube. After 7 days the supernatant was removed by centrifugation and the soil was allowed to air dry at room temperature

Radiochemistry of uranium

Energy Technology Data Exchange (ETDEWEB)

Gindler, J.E.

1962-03-01

This volume which deals with the radiochemistry of uranium is one of a series of monographs on radiochemistry of the elements. There is included a review of the nuclear and chemical features of particular interest to the radiochemist, a discussion of problems of dissolution of a sample and counting technique, and finally, a collection of radiochemical procedures for the element as found in the literature.

U-Pb ages of uraniferous opals and implications for the history of beryllium, fluorine, and uranium mineralization at Spor Mountain, Utah

Science.gov (United States)

Ludwig, K. R.; Lindsey, D.A.; Zielinski, R.A.; Simmons, K.R.

1980-01-01

The U-Pb isotope systematics of uraniferous opals from Spor Mountain, Utah, were investigated to determine the suitability of such material for geochronologic purposes, and to estimate the timing of uranium and associated beryllium and fluorine mineralization. The results indicate that uraniferous opals can approximate a closed system for uranium and uranium daughters, so that dating samples as young as ???1 m.y. should be possible. In addition, the expected lack of initial 230Th and 231Pa in opals permits valuable information on the initial 234U/238U to be obtained on suitable samples of ???10 m.y. age. The oldest 207Pb/235U apparent age observed, 20.8 ?? 1 m.y., was that of the opal-fluorite core of a nodule from a beryllium deposit in the Spor Mountain Formation. This age is indistinguishable from that of fission-track and K-Ar ages from the host rhyolite, and links the mineralization to the first episode of alkali rhyolite magmatism and related hydrothermal activity at Spor Mountain. Successively younger ages of 13 m.y. and 8-9 m.y. on concentric outer zones of the same nodule indicate that opal formed either episodically or continuously for over 10 m.y. Several samples of both fracture-filling and massive-nodule opal associated with beryllium deposits gave 207Pb/235U apparent ages of 13-16 m.y., which may reflect a restricted period of mineralization or perhaps an averaging of 21- and <13-m.y. periods of opal growth. Several samples of fracture-filling opal in volcanic rocks as young as 6 m.y. gave 207Pb/235U ages of 3.4-4.8 m.y. These ages may reflect hot-spring activity after the last major eruption of alkali rhyolite. ?? 1980.

Ecological considerations of natural and depleted uranium

International Nuclear Information System (INIS)

Hanson, W.C.

1980-01-01

Depleted 238 U is a major by-product of the nuclear fuel cycle for which increasing use is being made in counterweights, radiation shielding, and ordnance applications. This paper (1) summarizes the pertinent literature on natural and depleted uranium in the environment, (2) integrates results of a series of ecological studies conducted at Los Alamos Scientific Laboratory (LASL) in New Mexico where 70,000 kg of depleted and natural uranium has been expended to the environment over the past 34 years, and (3) synthesizes the information into an assessment of the ecological consequences of natural and depleted uranium released to the environment by various means. Results of studies of soil, plant, and animal communities exposed to this radiation and chemical environment over a third of a century provide a means of evaluating the behavior and effects of uranium in many contexts

Electrochemical investigation of tetravalent uranium β-diketones for active materials of all-uranium redox flow battery

International Nuclear Information System (INIS)

Yamamura, Tomoo; Shiokawa, Yoshinobu; Ikeda, Yasuhisa

2002-01-01

For active materials of the all-uranium redox flow battery for the power storage, tetravalent uranium β-diketones were investigated. The electrode reactions of U(ba) 4 and U(btfa) 4 were examined in comparison with that of U(acac) 4 , where ba denotes benzoylacetone, btfa benzoyltrifluoroacetone and acac acetylacetone. The cyclic voltammograms of U(ba) 4 and U(btfa) 4 solutions indicate that there are two series of redox reactions corresponding to the complexes with different coordination numbers of four and three. The electrode kinetics of the U(IV)/U(III) redox reactions for btfa complexes is examined. The obtained result supports that the uranium β-diketone complexes examined in the present study will serve as excellent active materials for negative electrolyte in the redox flow battery. (author)

Lithofacies-paleo-geography and uranium sedimentary facies in Hailar basin

International Nuclear Information System (INIS)

Qi Fucheng

1992-01-01

Cretaceous-Tertiary sedimentary paleo-structure and lithofacies-paleo-geography in Hailar Basin are described. Taking Chenqi coal field as an example, the sedimentary facies pattern of coal-bearing series characterized by alternating sedimentation of fluviatile and lacustrine-swampy facies is reconstructed. It is pointed out that this sedimentary facies not only controls the sedimentation and distribution of syngenetic uranium mineralization, but also is a favourable place that converges uranium-bearing solution and reduces and precipitates uranium for the second time in epigenetic mineralization

The importance of speculative uranium deposits

International Nuclear Information System (INIS)

Kaiser, H.; Roth-Seefrid, H.

1980-01-01

Since current known uranium deposits (5 million t U) will either have been exhausted by the end of the century, or must be held in reserve for the thermal converter reactors which will be in operation by that time, the development of nuclear energy after the year 2000 will depend to a large extent on the early availability of speculative uranium deposits. The speculative deposits represent, by definition, the quantities of uranium which are presumed to exist in addition to the 'known' deposits and which can ultimately be exploited according to current technical-economic and ecological standpoints. When viewed critically, however, the US-DOE model used for this purpose projects an over-optimistic picture of uranium supplies and was, therefore, only accepted by the INFCE with a series of limitations and reservations. Overall the model represents a well-founded reassurance for future uranium exploration - nothing more and nothing less. The model clearly shows that due to the long lead-in times considerable expenditure will be required for uranium exploration in the coming years. It is probable that this level of investment will have to be increased several times over in the 1990s as the search moves to greater depths and to less-accessible regions. (orig./UA) [de

Reactivity of uranium(IV) bridged chalcogenido complexes UIV–E–UIV (E = S, Se) with elemental sulfur and selenium: synthesis of polychalcogenido-bridged uranium complexes

OpenAIRE

Franke, Sebastian M.; Heinemann, Frank W.; Meyer, Karsten

2014-01-01

We report the syntheses, electronic properties, and molecular structures of a series of polychalcogenido-bridged dinuclear uranium species. These complexes are supported by the sterically encumbering but highly flexible, single N-anchored tris(aryloxide) chelator (AdArO)3N3−. Reaction of an appropriate uranium precursor, either the U(III) starting material, [((AdArO)3N)U(DME)], or the dinuclear mono-chalcogenido-bridged uranium(IV/IV) compounds [{((AdArO)3N)U(DME)}2(μ-E)] (E = S, Se), with el...

Lung Cancer in uranium miners

International Nuclear Information System (INIS)

Zhou Chundi; Fan Jixiong; Wang Liuhu; Huang Yiehan; Nie Guanghua

1987-01-01

This paper analyese the clinical data of 39 uranium miners with lung cancer and of 20 patients with lung cancer who have not been exposed to uranium as control. The age of uranium miners with lung cancer was 36∼61 with an average of 48.8, nine years earlier than that of the control group (57.3). In the uranium miner patients the right lung was more susceptible to cancer than the left, the ratio being 2.5:1. However, in the control group the right lung had an equal incidence of cancer as the left lung. The relative frequency of small cell anaplastic carcinoma in uranium miner was higher than that in the control group. In the miner patients the mean occupation history was 11.1 ± 5.2 years; the exposure dose to radon and its daughters in 50% patients was 0.504J(120 WLM). The etiologic factor of lung cancer in uranium miners is strongly attributed, in addition to smoking, to the exposure to radon and its daughters in uranium mines

Uranium: biokinetics and toxicity; Biocinetique et toxicite de l'uranium

Energy Technology Data Exchange (ETDEWEB)

Menetrier, F.; Renaud-Salis, V.; Flury-Herard, A

2000-07-01

This report was achieved as a part of a collaboration with the Fuel Cycle Direction. Its aim was to give the state of the art about: the behaviour of uranium in the human organism (biokinetics) after ingestion, its toxicity (mainly renal) and the current regulation about its incorporation. Both in the upstream and in the downstream of the fuel cycle, uranium remains, quantitatively, the first element in the cycle which is, at the present time, temporarily disposed or recycled. Such a considerable quantity of uranium sets the problem of its risk on the health. In the long term, the biosphere may be affected and consequently the public may ingest water or food contaminated with uranium. In this way, radiological and chemical toxicity risk may be activated. This report emphasizes: the necessity of confirming some experimental and epidemiological biokinetic data used or not in the ICRP models. Unsolved questions remain about the gastrointestinal absorption according to chemical form (valency state, mixtures...), mass and individual variations (age, disease) further a chronic ingestion of uranium. It is well established that uranium is mainly deposited in the skeleton and the kidney. But the skeleton kinetics following a chronic ingestion and especially in some diseases has to be more elucidated; the necessity of taking into account uranium at first as a chemical toxic, essentially in the kidney and determining the threshold of functional lesion. In this way, it is important to look for some specific markers; the problem of not considering chemical toxicity of uranium in the texts regulating its incorporation.

Biosolubilization of uranyl ions in uranium ores by hydrophyte plants

International Nuclear Information System (INIS)

Cecal, Alexandru; Calmoi, Rodica; Melniciuc-Puica, Nicoleta

2006-01-01

This paper investigated the bioleaching of uranyl ions from uranium ores, in aqueous medium by hydrophyte plants: Lemna minor, Azolla caroliniana and Elodea canadensis under different experimental conditions. The oxidation of U(IV) to U(VI) species was done by the atomic oxygen generated in the photosynthesis process by the aquatic plants in the solution above uranium ores. Under identical experimental conditions, the capacity of bioleaching of uranium ores decreases according to the following series: Lemna minor > Elodea canadensis > Azolla caroliniana. The results of IR spectra suggest the possible use of Lemna minor and Elodea canadensis as a biological decontaminant of uranium containing wastewaters. (author)

Operating conditions of T.B.P. line uranium purification plant, for uranium dioxide production

International Nuclear Information System (INIS)

Vardich, R.N.; La Gamma, A.M.; Anasco, R.; Soler, S.M.G. de; Isnardi, E.; Gea, V.; Chiaraviglio, R.; Matyjasczyk, E.; Aramayo, R.

1992-01-01

In this contribution are presented the operative conditions and the results obtained step of the Uranium dioxide production plant of Argentina. The refining step involve the Uranium concentrate dissolution, the silica ageing, the filtration and liquid - liquid extraction with n-tributyl phosphate solution in kerosene. The established operative conditions allow to obtain Uranyl nitrate solutions of nuclear purity in industrial scale. (author)

Radiation risk assessment of reprocessed uranium

International Nuclear Information System (INIS)

Cardenas, Hugo R.; Perez, Aldo E.; Luna, Manuel F.; Becerra, Fabian A.

1999-01-01

Reprocessed uranium contains 232 U, which is not found in nature, as well as 234 U which is present in higher proportion than in natural uranium. Both isotopes modify the radiological properties of the material. The paper evaluates the increase of the internal and external radiation risk on the base of experimental data and theoretical calculations. It also suggests measures to be taken in the production of fuel elements with slightly enriched uranium.The radiation risk of reprocessed uranium is directly proportional to the content of 232 U and 234 U as well as to the aging time of the material

Prospects of uranium in Baluchistan

International Nuclear Information System (INIS)

Aslam, M.; Rehman, M.A.

1981-01-01

A review of the geology of Baluchistan indicates that sedimentary rocks consisting of sandstones and conglomerates ranging from Paleocene to Miocene age were formed under the fluviatile conditions. The region underwent Late Cretaceous-Early Cenozic continent to continent collision resulting in varied metallogenic environments. Considering the criteria of favourability for the environments of uranium deposition, it is found that these rocks and the acidicigneous rocks of Cretaceous age are favourable for the occurrence of uranium. A radiometric prospecting programme is suggested to locate possible mineralization in the region. (author)

Uranium occurrences of the Thunder Bay-Nipigon-Marathon area

International Nuclear Information System (INIS)

Scott, J.F.

1987-01-01

During the 1981, 1982 and 1983 field seasons an inventory of all known uranium occurrences in the North Central Region of Ontario was undertaken. Three major categories of uranium occurrences were identified: uranium associated with the rocks of the Quetico Subprovince; uranium associated with the Proterozoic/Archean unconformity; and uranium associated with alkalic and carbonatite rocks of Late Precambrian age. Occurrences associated with the Quetico Belt are in white, albite-quartz-muscovite pegmatites. Occurrences associated with the Proterozoic/Archean unconformity are usually of high gradee (up to 12% U 3 O 8 ), nearly always hematized and are related to fault or shear zones proximal to the unconformity. Although of high grade, many of the unconformity related occurrences are very narrow (<1 m). Alkalic and carbonatite rocks of Late Precambrian age are an important source of uranium but possible metallurgical problems might downgrade their potential. The Quetico Subprovince is anomalously high in background uranium, and therefore contains important source rocks for uranium. Areas that have the highest potential for uranium deposits in the North Central Region are the Nipigon Basin area, and the areas underlain by the Gunflint and Rove Formations. All the high grade vein-type uranium deposits related to the unconformity are found within the Nipigon Basin. 126 refs

Proceedings of the JOWOG 22C (uranium) meeting

Energy Technology Data Exchange (ETDEWEB)

Nelson, T; Talaber, C; Wood, D H [eds.

1987-01-01

Lawrence Livermore National Laboratory was pleased to be host to the JOWOG 22C Meeting on June 9-11, 1987. This meeting was one of a continuing series on the subject of uranium and uranium alloys held between representatives of the United Kingdom and the United States under a treaty signed July 3, 1958. These, and similar meetings on other subjects, are controlled by the Department of Energy and the Joint Atomic Information Exchange Group (a combined agency of the Departments of Energy and Defense). The following topics were covered in the meeting: Use of Computers to Simulate Uranium; Corrosion and Chemical Stability; Superplasticity; Bonding, Corrosion, Etc.; Thermomechanical Properties and Fabrication; U-Ti Alloys; Uranium-Niobium Alloys; Physical Metallurgy and Testing; Miscellaneous Subjects; and Production and Facilities/Production Technology.

Uranium-series dating of some lake and dune deposits in south-east Australia

International Nuclear Information System (INIS)

Herczeg, A.L.

1987-01-01

A correction scheme developed over many years was used to obtain reliable dates for impure carbonates and gypsum from uranium disequilibrium analyses. The materials analyzed thus far and their sources are described. The results indicated that reliable dating can be obtained provided that there is no post-depositional alteration in the sample and that sufficient uranium is present. The object is to investigate further sites in order to reconstruct palaeohydrology and environments in Australia over the last 400000 years. 4 refs

Practical aspects of monitoring and dosimetry of long-lived dust in uranium mines and mills - determination of the annual limit on intake for uranium and uranium/thorium ore dust

International Nuclear Information System (INIS)

Duport, P.; Horvath, F.

1989-01-01

Based on the recommendations of ICRP Publication 26, the dosimetric and metabolic data of ICRP Publication 30, and using available information on the physical and solubility characteristics of uranium and uranium/thorium ore, the ALI values for airborne ore dust were calculated. Four hypothetical types of ore were considered: uranium ore with no radon emanation, uranium ore with 50% radon emanation, uranium/thorium ore with neither 222 Rn nor thoron emanation, and uranium/thorium ore with 50% 22 Rn and 220 Rn emanation. Furthermore, the ALI values were calculated assuming the radionuclides present in the ore were all: (a) solubility class Y: (b) solubility class W; and (c) equal parts of classes Y and W. The ALI values were also calculated for Activity Median Aerodynamic Diameters (AMAD) ranging from 1 to 10 μm. The results of the calculations show that the solubility class of the radionuclides is the single most important factor that governs ALI values. The ALI value for uranium and uranium-thorium ore dust is proportional to (AMAD) 0.5 for class Y materials, (AMAD) 0.2 for a mixture of equal parts of class Y and class W materials, and is independent of the AMAD for class W materials. A series of graphs is given from which it is possible to evaluate the ALI for airborne ore dust when the AMAD of the dust and the solubility characteristics are known approximately. (author)

The Streltsovskoye uranium district

International Nuclear Information System (INIS)

Ischukova, L.P.

1997-01-01

This paper describes the geology of the Streltsovskoye uranium district located in south-eastern Zabaikalie region, Chita Province, Siberia, Russia. This district hosts Russia's only currently active uranium production centre. The uranium ore was discovered from 1963 to 1967 by drilling below fluorite veins which had minor associated uranium mineralization and radioactive anomalies. The uranium occurs as large scale vein stockwork deposits of hydrothermal origin within a volcano-tectonic caldera formed by continental volcanism of Late Mesozoic age. Rocks occurring in the caldera include basalt and trachydacite, overlain by rhyolite, and with associated interbedded sediments. The ore bodies occur in steeply dipping faults, with the greatest concentrations located where faults along the margins of the caldera intersect steeply dipping, cross cutting, northeasterly and northwesterly striking faults. The Streltsovskoye caldera extends over an area of 150 km 2 and is underlain by a large batholith. The 19 identified uranium deposits occurred in structural features that cut through the caldera sequence and extend into the basement rocks. The caldera has a maximum thickness of 1400 metres. Details of several deposits are given, including descriptions of mineralization and associated alteration. (author). 10 figs

U-Th series nuclides in the Gulf of Mexico

International Nuclear Information System (INIS)

Scott, M.R.

1981-01-01

A study of U and Th series nuclides is being conducted on sediments from the Gulf of Mexico. Uranium concentrations as a function of depth have been determined, as well as changes in the 234 U/ 238 U activity ratio. The geochemical behavior of uranium in shelf sediments is discussed

Uranium potentialities of precambrian from Goias State

International Nuclear Information System (INIS)

Danni, J.C.M.; Marini, O.J.; Faria, A. de; Dardenne, M.A.

1983-01-01

A chrono-stratigraphy synthesis of geological unities from Precambrian, with emphasis on characterization of its depositional region, tectonics and or lithology is presented. The main ideas relating to uranium metallogeny in precambrian ages referring to geologic situation in Goias is described. The uranium occurrence associated to precambrian unities from region and some interpretations for evaluation the potentialities of uranium metallotect are also cited. (C.G.C.)

Fractal characters and hurst exponent of radon exhalation rate from uranium Tailings

International Nuclear Information System (INIS)

Hu Hanqiao; Tan Kaixuan; Li Chunguang; Lv Junwen; Liu Dong

2010-01-01

The uranium tailings radon exhalation is an important environmental problem. The change of the radon exhalation rate of uranium tailings with the time through laboratory experiments is measured, and the results show that the radon exhalation rate of the tailings change obviously with time in non-periodic oscillations. Applying fractal analysis to the radon exhalation rate time-series data by R/S method, the Hurst exponent of the entire time series data is 0.83, the fractal dimension is 1.17. Mobile Hurst exponent is between 0.5 and 0.8 in most cases. The Hurst exponent of the experiments in the later part are below 0.5. The exhalation rate of uranium tailings radon does not meet the long-term trend of random walk theory, the radon exhalation rate has long-term memory, but the short-term memory is not distinct. The radon exhalation from uranium tailings is a deterministic chaotic dynamics. (authors)

Sedimentary uranium deposits in France and French Union; Les gisements uraniferes dans les formations sedimentaires en France et dans l'Union francaise

Energy Technology Data Exchange (ETDEWEB)

Kervella, F. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1958-07-01

The author gives the actual state of our knowledge on uranium deposits found in recent years. Till now in precambrian formations only one important deposit has been found, at Mounana (Gabon) in a series of conglomeratic sandstones belonging to the 'Francevillien'. The observed mineralization is of the uranium-vanadium type. To the carboniferous formations corresponds in France a series of deposits, among which the most important ones are located at Saint-Hippolyte. Uranium as carburans, organic-bound complexes, is contained in lacustrine schists of Westphalian or lower Stephanian formations. A number of occurrences are also known in permo-triassic formations, particularly in the Vanoise Alps, in the Maritime Alps and in the Herault, where important occurrences have recently been found not far from Lodeve. The cretaceous and tertiary systems contain uranium deposits in phosphate rocks (Morocco, Senegal, Togo, Middle-Congo). Two sedimentary oligocene deposits are known in France. Lastly, the Vinaninkarena deposit in Madagascar, known for a long time, is the only important one reported in the quaternary series. (author) [French] L'auteur fait le point des connaissances acquises sur les gisements decouverts dans les formations sedimentaires en France et dans l'Union francaise au cours des dernieres annees. Les gisements sont classes selon l'age de la formation dans laquelle on les observe. Les terrains precambriens n'ont pour l'instant fourni qu'un seul gisement notable; situe a Mouana (Gabon). C'est en decembre 1956 que cet important gisement fut decouvert dans une serie de gres conglomeratiques appartenant au Francevillien. La mineralisation observee est du type vanadium-uranium. Au carbonifere correspond en France metropolitaine une serie de gisements d'interet variable. Les plus importants sont ceux de Saint-Hippolyte (Haut-Rhin) ou l'uranium est contenu dans des schistes lacustres du Westphalien ou du

Time averaging, ageing and delay analysis of financial time series

Science.gov (United States)

Cherstvy, Andrey G.; Vinod, Deepak; Aghion, Erez; Chechkin, Aleksei V.; Metzler, Ralf

2017-06-01

We introduce three strategies for the analysis of financial time series based on time averaged observables. These comprise the time averaged mean squared displacement (MSD) as well as the ageing and delay time methods for varying fractions of the financial time series. We explore these concepts via statistical analysis of historic time series for several Dow Jones Industrial indices for the period from the 1960s to 2015. Remarkably, we discover a simple universal law for the delay time averaged MSD. The observed features of the financial time series dynamics agree well with our analytical results for the time averaged measurables for geometric Brownian motion, underlying the famed Black-Scholes-Merton model. The concepts we promote here are shown to be useful for financial data analysis and enable one to unveil new universal features of stock market dynamics.

A Record of Uranium-Series Transport in Fractured, Unsaturated Tuff at Nopal I, Sierra Peña Blanca, Chihuahua, Mexico

Science.gov (United States)

Denton, J.; Goldstein, S. J.; Paviet, P.; Nunn, A. J.; Amato, R. S.; Hinrichs, K. A.

2015-12-01

In this study we utilize U-series disequilibria measurements to investigate mineral fluid interactions and the role fractures play in the geochemical evolution of an analogue for a high level nuclear waste repository, the Nopal I uranium ore deposit. Samples of fracture-fill materials have been collected from a vertical drill core and surface fractures. High uranium concentrations in these materials (12-7700 ppm) indicate U mobility and transport from the deposit in the past. U concentrations generally decrease with horizontal distance away from the ore deposit but show no trend with depth. Isotopic activity ratios indicate a complicated geochemical evolution in terms of the timing and extent of actinide mobility, possibly due to changing environmental (redox) conditions over the history of the deposit. 234U/238U activity ratios are generally distinct from secular equilibrium and indicate some degree of open system U behavior during the past 1.2 Ma. However, calculated closed system 238U-234U-230Th model ages are generally >313 ka and >183 ka for the surface fracture and drill core samples respectively, suggesting closed system behavior for U and Th over this most recent time period. Whole rock isochrons drawn for the drill core samples show that at two of three depths fractures have remained closed with respect to U and Th mobility for >200 ka. However, open system behavior for U in the last 350 ka is suggested at 67 m depth. 231Pa/235U activity ratios within error of unity suggest closed system behavior for U and Pa for at least the past 185 ka. 226Ra/230Th activity ratios are typically <1 (0.7-1.2), suggesting recent (<8 ka) radium loss and mobility due to ongoing fluid flow in the fractures. Overall, the mainly closed system behavior of U-Th-Pa over the past ~200 ka provides one indicator of the geochemical immobility of these actinides over long time-scales for potential nuclear waste repositories sited in fractured, unsaturated tuff.

Some characteristics of uranium oxides in China

International Nuclear Information System (INIS)

Xu, Guoqing; Wang, Aizhen; Gu, Qifang; Zhang, Jingyi; Zhang, Zhaoming; Huang, Yuzhu

1981-01-01

According to the analytical data of seventy-seven samples from several tens of uranium ore deposits and occurrences in China, chemical properties, cell dimensions and reflectance of uranium oxides are studied. Chemical properties of uranium oxides from different types of uranium ore deposits and the influence of various mineralization ages and hosts on the compositions of uranium oxides are presented. The influence of these factor such as mineralization temperatures, the compositions of hosts and geochemical background on the compositions of uranium oxides are evident. Lead in proterozoic uranium oxides is relatively enriched by the decay of radio-active elements. Cell dimensions have positive correlation with mineralization ages, formation temperatures and concentration of rare earths and Pb, and negative correlation with the oxidation coefficient. The cell size is an exponential function of the content in CaO. It is suggested that among the factors of influence the most important is the mineralization temperature. The size of ionic radius of elements substituted U 4 + and autooxidation of U 4 + during the process of the decay of radioactive elements are of secondary importance. The reflectance is independent of the content of CaO and SiO 2 . The reflectance is positively correlative with the cell size and negatively correlative with oxidation coefficient. The relation between the reflectance and the content of PbO is logarithmic

Estimation of uranium GI absorption fractions for children and adults

International Nuclear Information System (INIS)

Chen, J.; Lariviere, D.; Timmins, R.; Verdecchia, K.

2011-01-01

Uranium is ubiquitously found in drinking water and food. The gastrointestinal tract absorption fraction (f 1 ) is an important parameter in risk assessment of uranium burdens from ingestion. Although absorption of uranium from ingestion has been studied extensively in the past, human data concerning children and adults are still limited. In a previous study based on measurements of uranium concentration in 73 bone-ash samples collected by Health Canada, the absorption fractions for uranium ingestion were determined to be 0.093 ± 0.113 for infants, and 0.050 ± 0.032 for young children ranging from 1 to 7 y of age. To extend the study, a total of 69 bone-ash samples were selected for children and adults ranging from 7 to 25 y of age and residing in the same Canadian community that is known to have an elevated level of uranium in its drinking water supply. For each bone-ash sample, the total uranium concentration was measured by inductively coupled plasma mass spectrometry. To solve uranium transfer in the biokinetic model for uranium given in International Commission of Radiological Protection (ICRP) Publication 69 with estimated daily uranium intake, the program WinSAAM v3.0.1 was used. The absorption fractions were determined to be 0.030 ± 0.022 for children (7-18 y) and 0.021 ± 0.015 for adults (18-25 y). For anyone more than 18 y of age, the estimated f 1 value for uranium agree well with the ICRP recommended value of 0.02. Published by Oxford Univ. Press on behalf of the Canadian Government 2010. (authors)

Effect of aging on the general corrosion and stress corrosion cracking of uranium--6 wt % niobium alloy

International Nuclear Information System (INIS)

Koger, J.W.; Ammons, A.M.; Ferguson, J.E.

1975-11-01

Mechanical properties of the uranium-6 wt percent niobium alloy change with aging time and temperature. In general, the ultimate tensile strength and hardness reach a peak, while elongation becomes a minimum at aging temperatures between 400 and 500 0 C. The first optical evidence of a second phase was in the 400 0 C-aged alloy, while complete transformation to a two-phase structure was seen in the 600 0 C-aged alloy. The maximum-strength conditions correlate with the minimum stress corrosion cracking (SCC) resistance. The maximum SCC resistance is found in the as-quenched and 150, 200, and 600 0 C-aged specimens. The as-quenched and 300 0 C-aged specimens had the greatest resistance to general corrosion in aqueous chloride solutions; the 600 0 C-aged specimen had the least resistance

Depending on scientific and technological progress to prospect for superlarge uranium deposits. Across-century target for uranium resources exploration work in China

International Nuclear Information System (INIS)

Shen Feng

1995-01-01

After over 30 years' development, uranium resources exploration work in China has resulted in the discovery of more than 10 economic types of uranium deposits in 23 provinces (regions) of the whole country and large quantities of uranium reserves have been submitted which guarantee the development of nuclear industry in China. However, characteristics such as smaller size of deposits and ore bodies, and lower ore grade of discovered China's uranium deposits have brought about a series of problems on how to economically exploit and utilize these uranium resources. To prospect for superlarge uranium deposits is a guarantee of making uranium resources essentially meet the demand for the long-term development of nuclear industry in China, and is an important way of improving economic benefits in mining China's uranium resources. It is an important mark for uranium geological exploration work to go up a new step as well. China exhibits the geological environment in which various types of superlarge uranium deposits can be formed. Having the financial support from the state to uranium resources exploration work, having professional uranium exploration teams well-experienced in ore prospecting, having modernized uranium exploration techniques and equipment and also having foreign experience in prospecting for superlarge uranium deposits as reference, it is entirely possible to find out superlarge uranium deposits in China at the end of this century and at the beginning of next century. In order to realize the objective, the most important prerequisite is that research work on metallogenetic geological theory and exploration techniques and prospecting methodology for superlarge uranium deposits must be strengthened, and technical quality of the geological teams must be improved. Within this century, prospect targets should be selected and located accurately to carry out the emphatic breakthrough in exploration strategy

Initial process development for uranium bioprecipitation

International Nuclear Information System (INIS)

Truex, M.; Peyton, B.; Gorby, Y.; Valentine, N.

1994-01-01

Some bacteria can destabilize soluble metal complexes by enzymatically reducing the metal to a valence state where insoluble compounds are formed. For instance, oxidized uranium (VI) is highly soluble, but it precipitates from solution as the U(IV) oxide uraninite after microbial reduction. The advantage of this technology is that the uranium is easily separated from the aqueous phase, resulting in a small volume of relatively pure uraninite waste. A dissimilatory iron-reducing bacterium capable of uranium reduction was found to have a maximum growth rate of 0.142/hr, a Monod half-saturation constant of 3.4 mg/L, and a cellular yield of 0.071 mg-biomass/mg-iron for iron reduction at 30 C and pH 6.8. The kinetics of iron reduction were used to predict the performance of several reactor configurations for reduction of metals of interest such as uranium. A stirred-tank reactor in series with a plug-flow reactor was determined to be the best configuration for application of the bioprecipitation technology in a continuous-flow process

REIMEP-22 U age dating - Determination of the production date of a uranium certified test sample Inter-laboratory comparison, Report to participants

OpenAIRE

VENCHIARUTTI CELIA; VARGA ZSOLT; RICHTER Stephan; NICHOLL Adrian; KRAJKO JUDIT; JAKOPIC Rozle; MAYER Klaus; AREGBE Yetunde

2015-01-01

The REIMEP-22 inter-laboratory comparison (ILC) "U Age Dating - Determination of the production date of a uranium certified test sample" was organised by JRC-IRMM as support to the Nuclear Forensics International Technical Working Group (ITWG) This ILC was organised prior to the release of the candidate certified reference material IRMM-1000, produced in cooperation with JRC-ITU. The aim of REIMEP-22 was to determine the production date of the uranium certified test sample (i.e. the last chem...

National Uranium Resource Evaluation. Volume 1. Summary of the geology and uranium potential of Precambrian conglomerates in southeastern Wyoming

Energy Technology Data Exchange (ETDEWEB)

Karlstrom, K.E.; Houston, R.S.; Flurkey, A.J.; Coolidge, C.M.; Kratochvil, A.L.; Sever, C.K.

1981-02-01

A series of uranium-, thorium-, and gold-bearing conglomerates in Late Archean and Early Proterozoic metasedimentary rocks have been discovered in southern Wyoming. The mineral deposits were found by applying the time and strata bound model for the origin of uranium-bearing quartz-pebble conglomerates to favorable rock types within a geologic terrane known from prior regional mapping. No mineral deposits have been discovered that are of current (1981) economic interest, but preliminary resource estimates indicate that over 3418 tons of uranium and over 1996 tons of thorium are present in the Medicine Bow Mountains and that over 440 tons of uranium and 6350 tons of thorium are present in Sierra Madre. Sampling has been inadequate to determine gold resources. High grade uranium deposits have not been detected by work to date but local beds of uranium-bearing conglomerate contain as much as 1380 ppM uranium over a thickness of 0.65 meters. This project has involved geologic mapping at scales from 1/6000 to 1/50,000 detailed sampling, and the evaluation of 48 diamond drill holes, but the area is too large to fully establish the economic potential with the present information. This first volume summarizes the geologic setting and geologic and geochemical characteristics of the uranium-bearing conglomerates. Volume 2 contains supporting geochemical data, lithologic logs from 48 drill holes in Precambrian rocks, and drill site geologic maps and cross-sections from most of the holes. Volume 3 is a geostatistical resource estimate of uranium and thorium in quartz-pebble conglomerates.

National Uranium Resource Evaluation. Volume 1. Summary of the geology and uranium potential of Precambrian conglomerates in southeastern Wyoming

International Nuclear Information System (INIS)

Karlstrom, K.E.; Houston, R.S.; Flurkey, A.J.; Coolidge, C.M.; Kratochvil, A.L.; Sever, C.K.

1981-02-01

A series of uranium-, thorium-, and gold-bearing conglomerates in Late Archean and Early Proterozoic metasedimentary rocks have been discovered in southern Wyoming. The mineral deposits were found by applying the time and strata bound model for the origin of uranium-bearing quartz-pebble conglomerates to favorable rock types within a geologic terrane known from prior regional mapping. No mineral deposits have been discovered that are of current (1981) economic interest, but preliminary resource estimates indicate that over 3418 tons of uranium and over 1996 tons of thorium are present in the Medicine Bow Mountains and that over 440 tons of uranium and 6350 tons of thorium are present in Sierra Madre. Sampling has been inadequate to determine gold resources. High grade uranium deposits have not been detected by work to date but local beds of uranium-bearing conglomerate contain as much as 1380 ppM uranium over a thickness of 0.65 meters. This project has involved geologic mapping at scales from 1/6000 to 1/50,000 detailed sampling, and the evaluation of 48 diamond drill holes, but the area is too large to fully establish the economic potential with the present information. This first volume summarizes the geologic setting and geologic and geochemical characteristics of the uranium-bearing conglomerates. Volume 2 contains supporting geochemical data, lithologic logs from 48 drill holes in Precambrian rocks, and drill site geologic maps and cross-sections from most of the holes. Volume 3 is a geostatistical resource estimate of uranium and thorium in quartz-pebble conglomerates

Uranium resources and supply - demand to 2030

International Nuclear Information System (INIS)

Vance, R.

2010-01-01

Recent fluctuations in the market price for uranium have resulted in more activity in this sector over the past few years than in the preceding 20 years. Amidst this background, uranium demand is increasing. Construction of nuclear reactors is proceeding in some countries, ambitious expansion plans have been announced in others and the development of nuclear power programs to meet electricity demand and minimize greenhouse emissions in a cost effective manner is under consideration in many others. This paper reviews projections of nuclear growth and uranium demand and assesses the challenges faced by the uranium mining sector in meeting rising demand. Since the mid-1960 s, an international expert committee (the 'Uranium Group') formed by the OECD Nuclear Energy Agency and the International Atomic Energy Agency has published biennially comprehensive updates on global uranium resources, production and demand (the 'Red Book'). The most recent in this series, based on 2007 data and published in June 2008, includes a supply/demand projection to 2030. However, much has changed since the data were collected for this projection and an assessment of these changes and their impact on uranium production is included in this presentation. It is concluded that world identified uranium resources (5.45 million t U recoverable at costs up to US$130/kg U, or US$50/lb U 3 O 8 ) are adequate to meet projected future high case nuclear power requirements. However, recent financial market turmoil and lower uranium prices, the opaque nature of the uranium market itself, increased regulatory requirements, a scarcity of the required specialized labour and the fluctuating costs of raw materials makes the process of turning uranium resources in the ground into yellowcake in the can increasingly more challenging, particularly for new entrants. Considerable investment and expertise will be required to bring about the substantial increase in mine production required to meet future demand

Geological and geochemical aspects of uranium deposits: a selected, annotated bibliography

International Nuclear Information System (INIS)

Thomas, J.M.; Garland, P.A.; White, M.B.; Daniel, E.W.

1980-09-01

This bibliography, a compilation of 474 references, is the fourth in a series compiled from the National Uranium Resource Evaluation (NURE) Bibliographic Data Base. This data base was created for the Grand Junction Office of the Department of Energy's National Uranium Resource Evaluation Project by the Ecological Sciences Information Center, Oak Ridge National Laboratory. The references in the bibliography are arranged by subject category: (1) geochemistry, (2) exploration, (3) mineralogy, (4) genesis of deposits, (5) geology of deposits, (6) uranium industry, (7) geology of potential uranium-bearing areas, and (8) reserves and resources. The references are indexed by author, geographic location, quadrangle name, geoformational feature, and keyword

Radionuclides in sheep grazing near old uranium mines

Energy Technology Data Exchange (ETDEWEB)

Carvalho, Fernando P.; Oliveira, Joao M.; Malta, M. [Instituto Superior Tecnico/Campus Tecnologico e Nuclear/ (IST/CTN), Universidade de Lisboa, Estrada Nacional 10 - ao km 139,7, - 2695-066 Bobadela LRS (Portugal); Lemos, M.E. [Servicos de Alimentacao e Veterinaria da Regiao Centro, Bairro Na Sra dos Remedios, 6300 Guarda (Portugal); Vala, H.; Esteves, F. [Escola Superior Agraria de Viseu, Quinta da Alagoa, Estrada de Nelas, Ranhados,3500-606 Viseu (Portugal)

2014-07-01

During the past century extensive uranium mining took place in Portugal for radium and uranium production. Many uranium deposits were mined as open pits and after ore extraction and transportation to milling facilities, mining wastes were left on site. One uranium ore mining site, Boco Mine, was extracted in the 1960's and 70's and mining waste and open pits were left uncovered and non-remediated since closure of uranium mining activities. During the nineties a quarry for sand extraction was operated in the same site and water from a local stream was extensively used in sand sieving. Downstream the mine areas, agriculture soils along the water course are currently used for cattle grazing. Water from this stream, and water wells, soil, pasture and sheep meat were analyzed for radionuclides of the uranium series. The U- series radionuclide {sup 226}Ra was generally the highest in concentrations especially in soil, pasture, and in internal organs of sheep. Ra-226 concentrations averaged 1093±96 Bq/kg (dry weight) in soil, 43±3 Bq/kg (dw) in pasture, and 0.76±0.41 Bq/kg (dw) in muscle tissue of sheep grown there. Other sheep internal organs displayed much higher {sup 226}Ra concentrations, such as the brain and kidneys with 7.7±2.3 Bq/kg (dw) and 28±29 Bq/kg (dw), respectively. Results of tissue sample analysis for sheep grown in a comparison area were 2 to 11 times lower, depending on the tissue. Absorbed radiation doses for internal organs of sheep were computed and may exceed 20 mSv/y in the kidney. Although elevated, this absorbed radiation dose still is below the threshold for biological effects on mammals. Nevertheless, enhanced environmental radioactive contamination mainly due to radium was observed in the area of influence of this legacy uranium mine and there is potential food chain transfer for humans (authors)

Joint analysis of French and Czech uranium miners: lung cancer risk at low radon exposure rates and modifying effects of time since exposure and age at exposure

International Nuclear Information System (INIS)

Ladislav Tomasek; Agnes Rogel; Margot Tirmarche; Dominique Laurier

2006-01-01

The present analysis was conducted in the frame of European project 'Quantification of lung cancer risk after low radon exposure and low exposure rate: synthesis from epidemiologic and experimental data'. The overall goal of the project related to uranium miners was the evaluation of lung cancer dose-response relationship and of dose rate effects among European uranium miners exposed to low doses and low dose rates of radon decay products. In addition, modifying factors like attained age, age at exposure and time since exposure were investigated. The joint analysis of French and Czech uranium miners was conducted mainly in order to increase the statistical power and to allow a more detailed description of the variation of dose-response relationship in time. (N.C.)

Joint analysis of French and Czech uranium miners: lung cancer risk at low radon exposure rates and modifying effects of time since exposure and age at exposure

Energy Technology Data Exchange (ETDEWEB)

Ladislav Tomasek [National Radiation Protection Institute, Prague (Czech Republic); Agnes Rogel; Margot Tirmarche; Dominique Laurier [Institut de Radioprotection et de Surete Nucleaire, Fontenay-aux-Roses (France)

2006-07-01

The present analysis was conducted in the frame of European project 'Quantification of lung cancer risk after low radon exposure and low exposure rate: synthesis from epidemiologic and experimental data'. The overall goal of the project related to uranium miners was the evaluation of lung cancer dose-response relationship and of dose rate effects among European uranium miners exposed to low doses and low dose rates of radon decay products. In addition, modifying factors like attained age, age at exposure and time since exposure were investigated. The joint analysis of French and Czech uranium miners was conducted mainly in order to increase the statistical power and to allow a more detailed description of the variation of dose-response relationship in time. (N.C.)

Study of uranium content in drinking water, its; associated age-dependent radiation dose and water; quality parameters in four districts of NE-Punjab

International Nuclear Information System (INIS)

Sharma, Tanu; Sharma, Arvesh; Bajwa, B.S.; Mahajan, R.K.; Inderpreet Kaur

2017-01-01

Exposure due to natural uranium is of significant importance because of its largest contribution (nearly 85%) to the total collective dose of the world population. In the present study an attempt has been made to study the distribution of uranium in groundwater samples of some districts of NE-Punjab, India along with the estimation of radiation dose due to intake of uranium for different age groups. This study was carried out in a systematic manner in a grid pattern where 83, 91, 40 and 20 samples of drinking water have been collected from the Amritsar, Gurdaspur, Kapurthala and Pathankot districts which have been divided into small grids of 6 × 6 system

Lung cancer among workers at a uranium processing plant

International Nuclear Information System (INIS)

Cookfair, D.L.; Beck, W.L.; Shy, C.; Lushbaugh, C.C.; Sowder, C.L.

1983-01-01

This study examined the risk of dying from lung cancer among white males who received radiation to the lung as a result of inhaling uranium dust or the dust of uranium compounds. Cases and controls were chosen from a cohort of workers employed in a uranium processing plant during World War II. Cumulative radiation lung dose among study population members ranged from 0 to 75 rads. Relative risk was found to increase with increasing level of exposure even after controlling for age and smoking status, but only for those who were over the age of 45 when first exposed. A statistically significant excess in risk was found for men in this age group with a cumulative lung dose of 20 rads of more. These data suggest that older age groups may be more susceptible to radiation-induced lung cancer than younger age groups

Uranium

International Nuclear Information System (INIS)

Hamdoun, N.A.

2007-01-01

The article includes a historical preface about uranium, discovery of portability of sequential fission of uranium, uranium existence, basic raw materials, secondary raw materials, uranium's physical and chemical properties, uranium extraction, nuclear fuel cycle, logistics and estimation of the amount of uranium reserves, producing countries of concentrated uranium oxides and percentage of the world's total production, civilian and military uses of uranium. The use of depleted uranium in the Gulf War, the Balkans and Iraq has caused political and environmental effects which are complex, raising problems and questions about the effects that nuclear compounds left on human health and environment.

Uranium: biokinetics and toxicity

International Nuclear Information System (INIS)

Menetrier, F.; Renaud-Salis, V.; Flury-Herard, A.

2000-01-01

This report was achieved as a part of a collaboration with the Fuel Cycle Direction. Its aim was to give the state of the art about: the behaviour of uranium in the human organism (biokinetics) after ingestion, its toxicity (mainly renal) and the current regulation about its incorporation. Both in the upstream and in the downstream of the fuel cycle, uranium remains, quantitatively, the first element in the cycle which is, at the present time, temporarily disposed or recycled. Such a considerable quantity of uranium sets the problem of its risk on the health. In the long term, the biosphere may be affected and consequently the public may ingest water or food contaminated with uranium. In this way, radiological and chemical toxicity risk may be activated. This report emphasizes: the necessity of confirming some experimental and epidemiological biokinetic data used or not in the ICRP models. Unsolved questions remain about the gastrointestinal absorption according to chemical form (valency state, mixtures...), mass and individual variations (age, disease) further a chronic ingestion of uranium. It is well established that uranium is mainly deposited in the skeleton and the kidney. But the skeleton kinetics following a chronic ingestion and especially in some diseases has to be more elucidated; the necessity of taking into account uranium at first as a chemical toxic, essentially in the kidney and determining the threshold of functional lesion. In this way, it is important to look for some specific markers; the problem of not considering chemical toxicity of uranium in the texts regulating its incorporation

Isotopic feature and uranium dating of the volcanic rocks in the Okinawa Trough

Institute of Scientific and Technical Information of China (English)

无

2006-01-01

Volcanic rocks from the northern and middle Okinawa Trough were dated by uranium-series dating method. Differential fractions using magnetic procedure were designed to separate samples. New report on the ages and isotopic data of rocks in the northern trough (especially black pumice) was discussed. Based on the uranium dates and Sr-Nd isotopic ratio, magmatic evolution process of the Okinawa Trough was noted. Firstly, there have been wide silicic volcanic activities in the Okinawa Trough from late Pleistocene to present, and the volcanic rocks can be divided into three subgroups. Secondly, magma generally came from PREMA source area under the Okinawa Trough. Magmatic evolution in the northern trough was similar to the middle, but different to the south. Finally, volcanic activities indicated that opening of the southern Okinawa Trough did not happen due to the collision between Luson Arc and Eurasian Plate until the early Pleistocene.

Uranium extraction from gold-uranium ores

Energy Technology Data Exchange (ETDEWEB)

Laskorin, B.N.; Golynko, Z.Sh.

1981-01-01

The process of uranium extraction from gold-uranium ores in the South Africa is considered. Flowsheets of reprocessing gold-uranium conglomerates, pile processing and uranium extraction from the ores are presented. Continuous counter flow ion-exchange process of uranium extraction using strong-active or weak-active resins is noted to be the most perspective and economical one. The ion-exchange uranium separation with the succeeding extraction is also the perspective one.

Separation and Recovery of Uranium Metal from Spent Light Water Reactor Fuel via Electrolytic Reduction and Electrorefining

International Nuclear Information System (INIS)

Herrmann, S.D.; Li, S.X.

2010-01-01

A series of bench-scale experiments was performed in a hot cell at Idaho National Laboratory to demonstrate the separation and recovery of uranium metal from spent light water reactor (LWR) oxide fuel. The experiments involved crushing spent LWR fuel to particulate and separating it from its cladding. Oxide fuel particulate was then converted to metal in a series of six electrolytic reduction runs that were performed in succession with a single salt loading of molten LiCl - 1 wt% Li2O at 650 C. Analysis of salt samples following the series of electrolytic reduction runs identified the diffusion of select fission products from the spent fuel to the molten salt electrolyte. The extents of metal oxide conversion in the post-test fuel were also quantified, including a nominal 99.7% conversion of uranium oxide to metal. Uranium metal was then separated from the reduced LWR fuel in a series of six electrorefining runs that were performed in succession with a single salt loading of molten LiCl-KCl-UCl3 at 500 C. Analysis of salt samples following the series of electrorefining runs identified additional partitioning of fission products into the molten salt electrolyte. Analyses of the separated uranium metal were performed, and its decontamination factors were determined.

Combined ESR and U-series isochron dating of fossil tooth from Longgupo cave

International Nuclear Information System (INIS)

Han Fei; Yin Gongming; Liu Chunru; Jean-Jacques Bahain

2012-01-01

Background: In ESR and luminescence archaeological dating, the assessment of external radiation dose rate is one of the constant sources of uncertainty because of its variation in the past time and it cannot be determined accurately using the present-day measurements. Purpose: ESR isochron protocol was proposed to solve this uncertainty for the tooth samples. This protocol is applicable wherever multiple samples with different internal doses have all experienced a common external dose. The variable uranium concentration of tooth samples makes it possible to plot the equivalent dose versus the internal dose rate of each sample, and the slope of isochron line gives hence the age. For isochron dating of teeth, combined ESR/U-series dating analysis must be done together with isochron protocol. Methods: In this study, we try to use combined ESR/U-series isochron method on 5 tooth samples collected from immediate adjacent square in layer C Ⅲ'6 of Longgupo archaeological site, Chongqing, China. Combined ESR/U-series analysis with in situ external dose rate shows recent uranium uptake of all the samples. Results: The time-averaged external dose rate was iterative calculated by isochron protocol, and gives an isochron age of 1.77±0.09 Ma for layer C Ⅲ'6, which consistent with the mean US-ESR ages of 5 samples (1.64+0.16/-0.21 Ma) in the error range. The calculated time-averaged external dose rate(∼807 μGy/a) was basically in agreement with the in situ measured gamma dose rate value (8.50 μGy/a) in 2006, indicating the geochemical alterations may not occurred or do not affect the environmental dose rate obviously during the burial history. Conclusions: This study indicates the potential of solving both internal and external dose rate problems of ESR dating of fossil teeth by combining with U-series analysis and isochron protocol. (authors)

Uranium measurement by airborne gamma-ray spectrometry

International Nuclear Information System (INIS)

Grasty, R.L.

1975-01-01

In the airborne measurement of uranium, window type gamma-ray spectrometers are used and it is necessary to correct for scattered high energy radiation from thallium 208 in the thorium decay series. This radiation can be scattered in the crystal, in the ground, and in the air. A theory, analogous to the theory of radioactive decay, is developed; it can adequately explain the spectrum buildup in the uranium window for a point source of thorium oxide immersed to different depths in water and for a detector above the water. The theory is extended to predict the buildup as a function of altitude for detectors of different sizes and shows that errors in the airborne measurement of uranium can be significant if no allowance is made for radiation scattered in the ground and in the air

Uranium-Series Disequilibria in the Groundwater of the Shihongtan Sandstone-Hosted Uranium Deposit, NW China

Directory of Open Access Journals (Sweden)

Xinjian Peng

2015-12-01

Full Text Available Uranium (U concentration and the activities of 238U, 234U, and 230Th were determined for groundwaters, spring waters, and lake water collected from the Shihongtan sandstone-hosted U ore district and in the surrounding area, NW China. The results show that the groundwaters from the oxidizing aquifer with high dissolved oxygen concentration (O2 and oxidation-reduction potential (Eh are enriched in U. The high U concentration of groundwaters may be due to the interaction between these oxidizing groundwaters and U ore bodies, which would result in U that is not in secular equilibrium. Uranium is re-precipitated as uraninite on weathered surfaces and organic material, forming localized ore bodies in the sandstone-hosted aquifer. The 234U/238U, 230Th/234U, and 230Th/238U activity ratios (ARs for most water samples show obvious deviations from secular equilibrium (0.27–2.86, indicating the presence of water-rock/ore interactions during the last 1.7 Ma and probably longer. The 234U/238U AR generally increases with decreasing U concentrations in the groundwaters, suggesting that mixing of two water sources may occur in the aquifer. This is consistent with the fact that most of the U ore bodies in the deposit have a tabular shape originati from mixing between a relatively saline fluid and a more rapidly flowing U-bearing meteoric water.

Hydrogeologic and stratigraphic data pertinent to uranium mining, Cheyenne Basin, Colorado. Information series 12

International Nuclear Information System (INIS)

Kirkham, R.M.; O'Leary, W.; Warner, J.W.

1980-01-01

Recoverable low-grade uranium deposits occur in the Upper Cretaceous Fox Hills Sandstone and Laramie Formation in the Cheyenne Basin, Colorado. One of these deposits, the Grover deposit, has been test mined on a pilot scale using in-situ solution-mining techniques. A second deposit, the Keota deposit, is currently being licensed and will produce about 500,000 lb/yr (227,000 kg/yr) of yellowcake also using in-situ solution-mining techniques. Other uranium deposits exist in this area and will also probably be solution mined, although open-pit mining may possibly be employed at a few locations in the Cheyenne Basin. One of the principal environmental impacts of this uranium-mining activity is the potential effect on ground-water quality and quantity. In order to fully assess potential ground-water impacts, regulatory agencies and mine planners and operators must be familiar with regional geologic and hydrologic characteristics of the basin. The Oligocene White River Group and Upper Cretaceous Laramie Formation, Fox Hills Sandstone, and Pierre Shale contain important aquifers which supply water for domestic, stock-watering, irrigation, and municipal purposes in the study area. Should uranium mining seriously impact shallower aquifers, the upper Pierre and lower Fox Hills aquifers may become important sources of water. Water samples collected and analyzed from over 100 wells during this investigation provide baseline water-quality data for much of the study area. These analyses indicate water quality is highly variable not only between aquifers, but also within a particular aquifer. Many of the wells yield water that exceeds US Public Health drinking water standards for pH, TDS, sulfate, manganese, iron and selenium. Uranium, molybdenum, and vanadium concentrations are also high in many of these wells. 8 figures

New development stage of China's uranium industry

International Nuclear Information System (INIS)

Zhang Rong

2001-01-01

From the early 1980s China adjusted its uranium industry to better meet the market economy requirements. Until 1997, the adjustment has been completed. The technical and managerial improvements result in a more efficient uranium production. In 1996 a series of events related to the nuclear power development of China manifests very favorable situation for the uranium industry. The first two nuclear power plants with a total installed capacity of 2100 MW in the mainland of China have been operating safely and steadily for several years. The additional nuclear power projects to be constructed for the rest of this century are implemented in an all-round way. Four plants with eight reactors of a total of 6900 MW have entered their construction period in succession. In 1996 a commercial ISL mine in Xinjiang with annual capacity 100 tU was completed, and the larger scale of ISL mine is expected to be constructed by 2000. The Benxi uranium mine in northeast China was put into production. It applies some new mining and processing technologies and improved management, which might serve as a new model of uranium mines in China. (author)

Method for converting uranium oxides to uranium metal

International Nuclear Information System (INIS)

Duerksen, W.K.

1988-01-01

A method for converting uranium oxide to uranium metal is described comprising the steps of heating uranium oxide in the presence of a reducing agent to a temperature sufficient to reduce the uranium oxide to uranium metal and form a heterogeneous mixture of a uranium metal product and oxide by-products, heating the mixture in a hydrogen atmosphere at a temperature sufficient to convert uranium metal in the mixture to uranium hydride, cooling the resulting uranium hydride-containing mixture to a temperature sufficient to produce a ferromagnetic transition in the uranium hydride, magnetically separating the cooled uranium hydride from the mixture, and thereafter heating the separated uranium hydride in an inert atmosphere to a temperature sufficient to convert the uranium hydride to uranium metal

The Age of the 20 Meter Solo River Terrace, Java, Indonesia and the Survival of Homo erectus in Asia

Science.gov (United States)

Indriati, Etty; Swisher, Carl C.; Lepre, Christopher; Quinn, Rhonda L.; Suriyanto, Rusyad A.; Hascaryo, Agus T.; Grün, Rainer; Feibel, Craig S.; Pobiner, Briana L.; Aubert, Maxime; Lees, Wendy; Antón, Susan C.

2011-01-01

Homo erectus was the first human lineage to disperse widely throughout the Old World, the only hominin in Asia through much of the Pleistocene, and was likely ancestral to H. sapiens. The demise of this taxon remains obscure because of uncertainties regarding the geological age of its youngest populations. In 1996, some of us co-published electron spin resonance (ESR) and uranium series (U-series) results indicating an age as young as 35–50 ka for the late H. erectus sites of Ngandong and Sambungmacan and the faunal site of Jigar (Indonesia). If correct, these ages favor an African origin for recent humans who would overlap with H. erectus in time and space. Here, we report 40Ar/39Ar incremental heating analyses and new ESR/U-series age estimates from the “20 m terrace" at Ngandong and Jigar. Both data sets are internally consistent and provide no evidence for reworking, yet they are inconsistent with one another. The 40Ar/39Ar analyses give an average age of 546±12 ka (sd±5 se) for both sites, the first reliable radiometric indications of a middle Pleistocene component for the terrace. Given the technical accuracy and consistency of the analyses, the argon ages represent either the actual age or the maximum age for the terrace and are significantly older than previous estimates. Most of the ESR/U-series results are older as well, but the oldest that meets all modeling criteria is 143 ka+20/−17. Most samples indicated leaching of uranium and likely represent either the actual or the minimum age of the terrace. Given known sources of error, the U-series results could be consistent with a middle Pleistocene age. However, the ESR and 40Ar/39Ar ages preclude one another. Regardless, the age of the sites and hominins is at least bracketed between these estimates and is older than currently accepted. PMID:21738710

Overview of Qatecalovo-Kulaming uranium metallogenic region

International Nuclear Information System (INIS)

Zhao Fengmin

2011-01-01

Qatecalovo-Kulaming uranium metallogenic region is the earliest discovered volcanic-type uranium metallogenic region in the world, which which is located in the Kulaming uplift of Middle Tianshan Variscan orogenic belt. Ten deposits have been discovered in the mine area, over 20000 t metallic uranium has been mined out. Uranium deposits mainly occurred in Late Palaeozoic volcanic depression, and the volcanic rocks are characterized by the great lithologic change from andesite to rhyolite. Mineralization age is from 260 to 270 Ma. The tectonic unit in which the metallogenic region is located can extend eastward into China. Therefore, the ore-forming condition study on this tectonic unit can be used to guide the prospection for Palaeozoic volcanics uranium deposit in northwestern China. (author)

The challenge of dating Early Pleistocene fossil teeth by the combined uranium series-electron spin resonance method: the Venta Micena palaeontological site (Orce, Spain)

International Nuclear Information System (INIS)

Duval, M.; Falgueres, Ch.; Bahain, J.J.; Shao, Q.; Grun, R.; Aubert, M.; Hellstrom, J.; Dolo, J.M.; Agusti, J.; Martinez-Navarro, B.; Palmqvist, P.; Toro-Moyano, I.

2011-01-01

The palaeontological site of Venta Micena (Orce, Andalusia, Spain) lies in the eastern sector of the Guadix-Baza basin, one of the best documented areas in Europe for Plio-Pleistocene bio-stratigraphy. The combination of bio-chronological and palaeo-magnetic results, combined with the radiometric data obtained for Atapuerca Sima del Elefante, indicated that the Venta Micena stratum was formed between the Jaramillo and Olduvai palaeo-magnetic events, most likely between 1.22 and 1.77 Ma. Five fossil teeth from two outcrops (sites A and B) were selected to assess the potential of combined uranium series-electron spin resonance (US-ESR) dating of Early Pleistocene sites. Although the US-ESR results of the first outcrop showed a large scatter between the three teeth, the mean age of 1.37 ± 0.24 Ma can be considered a reasonable age estimate for Venta Micena. The mean ESR age of 0.62 ± 0.03 Ma obtained for site B seems to be a severe underestimation when compared with the independent age control. This underestimation is attributed to a relative recent U-mobilization event that led to some U-leaching. The results show that any ESR age calculations of old samples are extremely sensitive to variations in the measured 230 Th/ 234 U ratios in dental tissues. Although the results demonstrate that ESR can in principle be applied to Early Pleistocene sites, they also reveal the complexity of dating such old teeth. It is necessary to continue research in several directions, such as study of the behaviour of ESR signals in old teeth and understanding recent U-mobilization processes, to improve the reliability of the combined US-ESR dating method applied to Early Pleistocene times, a period for which the number of available numerical dating techniques is very limited. (authors)

Temperature Dependence of Uranium and Vanadium Adsorption on Amidoxime-Based Adsorbents in Natural Seawater

Energy Technology Data Exchange (ETDEWEB)

Kuo, Li-Jung [Marine Sciences Laboratory, Pacific Northwest National Laboratory, Sequim WA 98382 USA; Gill, Gary A. [Marine Sciences Laboratory, Pacific Northwest National Laboratory, Sequim WA 98382 USA; Tsouris, Costas [Oak Ridge National Laboratory, Oak Ridge TN 37831 USA; Rao, Linfeng [Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley CA 94720 USA; Pan, Horng-Bin [Department of Chemistry, University of Idaho, Moscow ID 83844 USA; Wai, Chien M. [Department of Chemistry, University of Idaho, Moscow ID 83844 USA; Janke, Christopher J. [Oak Ridge National Laboratory, Oak Ridge TN 37831 USA; Strivens, Jonathan E. [Marine Sciences Laboratory, Pacific Northwest National Laboratory, Sequim WA 98382 USA; Wood, Jordana R. [Marine Sciences Laboratory, Pacific Northwest National Laboratory, Sequim WA 98382 USA; Schlafer, Nicholas [Marine Sciences Laboratory, Pacific Northwest National Laboratory, Sequim WA 98382 USA; D' Alessandro, Evan K. [Rosensteil School of Marine and Atmospheric Chemistry, University of Miami, Miami FL 33149 USA

2018-01-16

The apparent enthalpy and entropy of the complexation of uranium (VI) and vanadium (V) with amidoxime ligands grafted onto polyethylene fiber was determined using time series measurements of adsorption capacities in natural seawater at three different temperatures. The complexation of uranium was highly endothermic, while the complexation of vanadium showed minimal temperature sensitivity. Amidoxime-based polymeric adsorbents exhibit significantly increased uranium adsorption capacities and selectivity in warmer waters.

Uranium and thorium migration under dislocative metamorphism

International Nuclear Information System (INIS)

Titov, V.K.; Bilibina, T.V.; Dashkova, A.D.; Il'in, V.K.; Makarova, L.I.; Shmuraeva, L.Ya.

1978-01-01

Investigated were peculiarities of uranium and thorium behaviour in the process of dislocation metamorphism on the basis of regional fracture zones of early-proterozoic embedding of Ukrainian, Aldan and Baltic shields. The studied zones correspond to tectonite of green-shale and almandin-amphibolite facies of regional metamorphism according to mineral associations. The most peculiar feature of the tectonites of green-shale facies is uranium presence in migrationally able forms, which can be involved afterwards into the ore process by hydrothermal solutions. Adsorved forms of uranium on the crystal surface or separate grains and in the cracks, as well as microinclusions of uranium minerals, selectively timed to mineral structure defects prevail among easily mobile uranium compounds. Dissolved uranium is present, evidently in gas-liquid inclusions in minerals and pore waters. There forms of uranium presence are peculiar for epidote-chlorite mylonites, as well as cataclasites and diaphthorites related to them by blastomylonites of almandin-amphibolite facies. Wide range of manifestation of this process, caused by multikilometer extension of deep fracture zones permit to consider the formations of green-shale facies of dislocation metamorphism as one of the main uranium sources in deposit formation in different uranium-ore associations different age

Perilaku kekuatan fatigue paduan aluminium seri 2014 akibat proses termomekanikal aging

Directory of Open Access Journals (Sweden)

Sujita -

2012-11-01

Full Text Available Aluminium alloy seri 2014 is material which is often used in industry. Because excellence of mechanic properties. But also have the weakness at properties of strength fatigue. Though fatigue strength is important parameter in desain, especially if application at condition of dinamic loading, so that need the treatment to improve it. Fatigue strength go together the micro structure and mode of failure of failure of effect of stress concentration. Aging treatment ordinary done not yet given the influence which even on the contrary. Inconsistence of fatigue strength alluminium alloy show the phenomenon which must be research instructing at repair of fatigue strength , so that need the advanced treatment in the form of termomechanical aging. The research conducted by using alluminium alloy series 2014 formed by specimen fatigue test of the size diameter 8 mm and long 87 mm relate at standart (ASTM E 513, continued treatment of termomechanical aging, tested the fatigue, and monitoring microstructure of change. By structure micro, the treatmentTMA have the effect which sicnificant to improvement of Alluminium alloy series 2104 fatigue strength. Generally entire process TMA improve of limit fatigue from specimen at condition early of limit fatigue 48.3 N / mm2 (48.3 MPA, mounting to become 50 until MPA, or mount 3.4 % until 44.9%. With the process of termomechanical aging TMA I, happened the increasing of cycle number equal to, 26.3 %, at treatment of TMA II go up equal to 62 % and 89.8% at process of TMA III, at maximal loading (180 Mpa.

Uranium in the black schists of Goesan (Ogcheon, Korea): relationships between organic matter and uranium

International Nuclear Information System (INIS)

Trichet, J.; Chun-Hyuck, O.

1990-01-01

The uranium deposit of Goesan is polyphased: its genesis resulted from sedimentary, diagenetic and metamorphic processes which occurred from late Proterozoic (presumed age of the deposition of the black shales) to late Trias. By its geochemical characters, this deposit resulted from the affinity existing between uranium and organic matter. The latter had a role both through the formation of organo-metallic complexes and as a reducing agent of the metal during the diagenetic evolution. Beside these factors favourable to metal accumulation, the possible development of evaporitic conditions and tectono-metamorphic processes can also have played an important role in the reconcentration of uranium as well as other metals [fr

Method for converting uranium oxides to uranium metal

Science.gov (United States)

Duerksen, Walter K.

1988-01-01

A process is described for converting scrap and waste uranium oxide to uranium metal. The uranium oxide is sequentially reduced with a suitable reducing agent to a mixture of uranium metal and oxide products. The uranium metal is then converted to uranium hydride and the uranium hydride-containing mixture is then cooled to a temperature less than -100.degree. C. in an inert liquid which renders the uranium hydride ferromagnetic. The uranium hydride is then magnetically separated from the cooled mixture. The separated uranium hydride is readily converted to uranium metal by heating in an inert atmosphere. This process is environmentally acceptable and eliminates the use of hydrogen fluoride as well as the explosive conditions encountered in the previously employed bomb-reduction processes utilized for converting uranium oxides to uranium metal.

The importance of the radioactive decay study on prospecting, research and plough of uranium

International Nuclear Information System (INIS)

Juliao, B.

1990-01-01

A radioactive decay series such as that of U-238 is said to be in a state of secular equilibrium when the number of atoms of each daughter being produced in the series is equal to the number of atoms of that daughter being lost be radioactive decay. When this condition exists, it is possible to determine the amount of the parent of the decay series by measuring the radiation from daughter element. Radioactive disequilibrium is quite a common occurrence in roll-front or sandstone-type uranium deposits. The reason is that uranium may be mobile when oxidized and daughter products formation lags behind. This leads to a distribution of radioelements wherein the daughter products (e.g. Bi - 214) are left behind, creating a daughter excess or parent-deficiency state, with strong gamma ray activity. Miners should receive from geologists a precise and sufficiently detailed geological report, including all the informations about disequilibrium problems of the uranium, deposits. (author)

Uranium

International Nuclear Information System (INIS)

Cuney, M.; Pagel, M.; Leroy, J.

1992-01-01

First, this book presents the physico-chemical properties of Uranium and the consequences which can be deduced from the study of numerous geological process. The authors describe natural distribution of Uranium at different scales and on different supports, and main Uranium minerals. A great place in the book is assigned to description and classification of uranium deposits. The book gives also notions on prospection and exploitation of uranium deposits. Historical aspects of Uranium economical development (Uranium resources, production, supply and demand, operating costs) are given in the last chapter. 7 refs., 17 figs

National Uranium Resource Evaluation: Newcastle Quadrangle, Wyoming and South Dakota

International Nuclear Information System (INIS)

Santos, E.S.; Robinson, K.; Geer, K.A.; Blattspieler, J.G.

1982-09-01

Uranium resources of the Newcastle 1 0 x2 0 Quadrangle, Wyoming and South Dakota were evaluated to a depth of 1500 m (5000 ft) using available surface and subsurface geologic information. Many of the uranium occurrences reported in the literature and in reports of the US Atomic Energy Commission were located, sampled and described. Areas of anomalous radioactivity, interpreted from an aerial radiometric survey, were outlined. Areas favorable for uranium deposits in the subsurface were evaluated using gamma-ray logs. Based on surface and subsurface data, two areas have been delineated which are underlain by rocks deemed favorable as hosts for uranium deposits. One of these is underlain by rocks that contain fluvial arkosic facies in the Wasatch and Fort Union Formations of Tertiary age; the other is underlain by rocks containing fluvial quartzose sandstone facies of the Inyan Kara Group of Early Cretaceous age. Unfavorable environments characterize all rock units of Tertiary age above the Wasatch Formation, all rock units of Cretaceous age above the Inyan Kara Group, and most rock units of Mesozoic and Paleozoic age below the Inyan Kara Group. Unfavorable environments characterize all rock units of Cretaceous age above the Inyan Kara Group, and all rock units of Mesozoic and Paleozoic age below the Inyan Kara Group

National Uranium Resource Evaluation: Newcastle Quadrangle, Wyoming and South Dakota

Energy Technology Data Exchange (ETDEWEB)

Santos, E S; Robinson, K; Geer, K A; Blattspieler, J G

1982-09-01

Uranium resources of the Newcastle 1/sup 0/x2/sup 0/ Quadrangle, Wyoming and South Dakota were evaluated to a depth of 1500 m (5000 ft) using available surface and subsurface geologic information. Many of the uranium occurrences reported in the literature and in reports of the US Atomic Energy Commission were located, sampled and described. Areas of anomalous radioactivity, interpreted from an aerial radiometric survey, were outlined. Areas favorable for uranium deposits in the subsurface were evaluated using gamma-ray logs. Based on surface and subsurface data, two areas have been delineated which are underlain by rocks deemed favorable as hosts for uranium deposits. One of these is underlain by rocks that contain fluvial arkosic facies in the Wasatch and Fort Union Formations of Tertiary age; the other is underlain by rocks containing fluvial quartzose sandstone facies of the Inyan Kara Group of Early Cretaceous age. Unfavorable environments characterize all rock units of Tertiary age above the Wasatch Formation, all rock units of Cretaceous age above the Inyan Kara Group, and most rock units of Mesozoic and Paleozoic age below the Inyan Kara Group. Unfavorable environments characterize all rock units of Cretaceous age above the Inyan Kara Group, and all rock units of Mesozoic and Paleozoic age below the Inyan Kara Group.

Uranium

International Nuclear Information System (INIS)

Poty, B.; Cuney, M.; Bruneton, P.; Virlogeux, D.; Capus, G.

2010-01-01

With the worldwide revival of nuclear energy comes the question of uranium reserves. For more than 20 years, nuclear energy has been neglected and uranium prospecting has been practically abandoned. Therefore, present day production covers only 70% of needs and stocks are decreasing. Production is to double by 2030 which represents a huge industrial challenge. The FBR-type reactors technology, which allows to consume the whole uranium content of the fuel, is developing in several countries and will ensure the long-term development of nuclear fission. However, the implementation of these reactors (the generation 4) will be progressive during the second half of the 21. century. For this reason an active search for uranium ores will be necessary during the whole 21. century to ensure the fueling of light water reactors which are huge uranium consumers. This dossier covers all the aspects of natural uranium production: mineralogy, geochemistry, types of deposits, world distribution of deposits with a particular attention given to French deposits, the exploitation of which is abandoned today. Finally, exploitation, ore processing and the economical aspects are presented. Contents: 1 - the uranium element and its minerals: from uranium discovery to its industrial utilization, the main uranium minerals (minerals with tetravalent uranium, minerals with hexavalent uranium); 2 - uranium in the Earth's crust and its geochemical properties: distribution (in sedimentary rocks, in magmatic rocks, in metamorphic rocks, in soils and vegetation), geochemistry (uranium solubility and valence in magmas, uranium speciation in aqueous solution, solubility of the main uranium minerals in aqueous solution, uranium mobilization and precipitation); 3 - geology of the main types of uranium deposits: economical criteria for a deposit, structural diversity of deposits, classification, world distribution of deposits, distribution of deposits with time, superficial deposits, uranium

Valence-associated uranium isotope fractionation of uranium enriched phosphate in a shallow aquifer, Lee County, Florida

International Nuclear Information System (INIS)

Weinberg, J.M.; Levine, B.R.; Cowart, J.B.

1993-01-01

The source of anomalously high concentrations of uranium, characterized by U-234/U-238 activity ratios significantly less than unity, in shallow groundwaters of Lee County, Florida, was investigated. Uranium in cores samples was separated into U(IV) and U(VI) oxidation state fractions, and uranium analyses were conducted by alpha spectrometry. Uranium mobility was also studied in selected leaching experiments. Results indicate that mobilization of unusually soluble uranium, present in uranium enriched phosphate of the Pliocene age Tamiami Formation at determined concentrations of up to 729 ppm, is the source for high uranium concentrations in groundwater. In leaching experiments, approximately one-third of the uranium present in the uranium enriched phosphate was mobilized into the aqueous phase. Results of previous investigations suggest that U-234, produced in rock by U-238 decay, is selectively oxidized to U(VI). The uranium enriched phosphate studied in this investigation is characterized by selective reduction of U-234, with a pattern of increasing isotopic fractionation with core depth. As a consequence, U-234/U-238 activity ratios greater than 1.0 in the U(IV) fraction, and less than 1.0 in the U(VI) fraction have developed in the rock phase. In leaching experiments, the U(VI) fraction from the rock was preferentially mobilized into the aqueous phase, suggesting that U-234/U-238 activity ratios of leaching groundwaters are strongly influenced by the isotopic characteristics of the U(VI) fraction of rock. It is suggested that preferential leaching of U(VI), present in selectivity reduced uranium enriched phosphate, is the source for low activity ratio groundwaters in Lee County

Results of geochemical and mineralogical studies on uranium in Zechstein copper-bearing strata from Lubin-Polkowice area

International Nuclear Information System (INIS)

Bareja, E.

1977-01-01

The paper presents the results of geochemical and mineralogical studies on uranium in Zechstein copper-bearing strata from the Lubin-Polkowice area. It was found that particular lithofacial varietes of Zechstein copper-bearing strata are characterized by different concentration of uranium. The mineralogical studies made possible determination of the nature of uranium mineralization and the interdependence between uranium and lithology of copper-bearing strata. An interesting uranium mineralization was found in tectonic breccias which yield black blende and schroeckingerite as well as calcite, gypsum, pyrite, hematite and geothite. Secondary minerals such as schroeckingerite and geothite evidence intense weathering processes acting in the copper deposit. The highest value of geochemical background of uranium in the copper-bearing series is displayed by basel copper-bearing shales (so called pitch-black shales) - 68.10 x 10 -40 /0 U. Statistical distribution of that element is unimodal. Distribution of uranium is polymodal in basal sandstones of the copper-bearing series. The geochemical background of red-coloured sandstones (Rotliegendes) is low, equalling 0.39 x 10 40 /0 U, whilst that of gray-coloured sandstones (Zechstein) - 2.32 x 10 -40 /0 U. An anomallous population (344.0 x 10 -40 /0 U) found in the case of gray sandstones of the Lubin-Polkowice area evidences the effects of secondary processes on concentration of uranium. In sandstones occur black blende, carburanes as well as calcite, hematite and goethite. A bimodal distribution of uranium was found in carbonate series. Limestones are characterized by low value of geochemical background (Dsub(x1) = 0.78 x 10 -40 /0 U) whilst dolomites by markedly higher values of the background (Dsub(x2) = 2.73 x 10 -40 /0 U). (author)

Uranium enrichment

International Nuclear Information System (INIS)

1991-11-01

This paper analyzes under four different scenarios the adequacy of a $500 million annual deposit into a fund to pay for the cost of cleaning up the Department of Energy's (DOE) three aging uranium enrichment plants. These plants are located in Oak Ridge, Tennessee; Paducah, Kentucky; and Portsmouth, Ohio. In summary the following was found: A fixed annual $500 million deposit made into a cleanup fund would not be adequate to cover total expected cleanup costs, nor would it be adequate to cover expected decontamination and decommissioning (D and D) costs. A $500 million annual deposit indexed to an inflation rate would likely be adequate to pay for all expected cleanup costs, including D and D costs, remedial action, and depleted uranium costs

Uranium in spring water and bryophytes at Basin Creek in central Idaho

International Nuclear Information System (INIS)

Shacklette, H.T.; Erdman, J.A.

1982-01-01

Arkosic sandstones and conglomerates of Tertiary age beneath the Challis Volcanics of Eocene age at Basin Creek, 10 km northeast of Stanley, Idaho, contain uranium-bearing vitrainized carbon fragments. The economic potential of these sandstones and conglomerates is currently being assessed. Water from 22 springs and associated bryophytes were sampled; two springs were found to contain apparently anomalous concentrations (normalized) of uranium. Water from a third spring contained slightly anomalous amounts of uranium, and two species of mosses at the spring contained anomalous uranium and high levels of both cadmium and lead. Water from a fourth spring was normal for uranium, but the moss from the water contained a moderate uranium level and highly anomalous concentrations of lead, germanium, and thallium. These results suggest that, in the Basin Creek area, moss sampling at springs may give a more reliable indication of uranium occurrence than would water sampling. (Auth.)

Early cretaceous zircon SHRIMP U-Pb age of the trachyte and its significances of the Gan-Hang belt

International Nuclear Information System (INIS)

Liu Feiyu; Wu Jianhua; Liu Shuai

2009-01-01

The Shixi basin was located at Gan-Hang tectonic volcanic uranium deposit of rock-magma belt which belong to a part of the Mesozoic volcanic rocks in the northeastern of China. The appearance of the trachyte in Shixi basin have the majoy elements characteristic of the shoshonite series volcanic rocks. To determine the geological age of trachyte have very important significance on the geodynamics research and the study on the cause of uranium mineralization. The zircons of the trachyte have clear ring and high Th/U ratio which belong to the typical magmatic zircons. The zircon SHRIMP U-Pb dating resules show that 14points' age range is very smaller is 132-144 Ma and the weighted average age is (137.00±0.94)Ma which represents the diagenetic age of volcanic rocks. Accronding to the latest International Stratigraphic Chart the boundary of Jurassic and Cretaceous is (145.4±4.0)Ma. So the trachyte of Shixi Group belong to early Cretaceous. The large-scale acidic volcanic activity occurred in the Early Cretaceous in Southeastern China, and the Volcanic uranium deposit of Gan-Hang tectonic belt relate to Alkali metasomatism Uranium mineralization also occurred in the Early Cretaceous (120-130 Ma). The determined of trachyte in Shixi Group in the Early Cretaceous show that the acidic volcanic activity have connection with magma activity and the early Uranium mineralization consistent with the Alkali magma activity. (authors)

Preferential adsorption of uranium ions in aqueous solutions by polymers

International Nuclear Information System (INIS)

Sakuragi, Masako; Ichimura, Kunihiro; Fujishige, Shoei; Kato, Masao

1981-01-01

Amidoxime fiber and triazine fiber were prepared by chemical modification of commercially available polyacrylonitril fiber. It was found that the Amidoxime fiber is efficient to adsorb uranium ions in the artificial sea water. The efficiency of the preferential adsorption decreases by treatment the material with an acid-or an alkaline-solution. The triazine fiber adsorbs uranium ions only in aqueous solutions of such uranyl acetate, in the absence of other ions. In the artificial sea water, it adsorbs other ions instead of uranium. The preferential adsorption of uranium ions was further investigated with a series of polystyrenesulfonamides. Among the polystyrene derivatives, those having carboxyl groups, derived from imino diacetic acid (PSt-Imi), β-alanine (PSt-Ala), glycine (PSt-Gly), and sarcosine (PSt-Sar) were qualified for further discussion. However, it was found that the amount of adsorption of uranium ions by PSt-Imi decreases with increasing the volume of the artificial sea water and/or the duration of the treatment. Taking into account the facts, the preferential adsorption of uranium ions by PSt-Imi in aqueous solution was discussed in detail. (author)

Present exploration status of the Lianshanguan uranium deposit, Northeast China

International Nuclear Information System (INIS)

Fei, Q.; Shaokang, H.

1980-01-01

During recent years surface radiometry has revealed a series of anomalies and uranium occurrences in the Lianshanguan region of Northeast China which are present in Proterozoic Formations. Several significant uranium occurrences were tested by trenching and core drilling which resulted in the discovery of the Lianshanguan uranium deposit in 1978. The ore bodies of economic significance are located at a depth of 38-250m. Potential reserves are 1000 tons of U 3 O 8 . The geological setting of the Lower Proterozoic Lianshanguan uranium deposit has a certain similarity to the Alligator Rivers Region, Northern Territory, Australia. However, the Lianshanguan deposit occurs in detrital formations (in the lower part of the Lower Proterozoic sequence), adjacent to a migmatitic zone; it is overlain by carbonate argillitic rocks. The discovery of the Lianshanguan deposit indicates a potential for further uranium discoveries in northeast China, where Proterozoic sequences are well developed. The Lianshanguan uranium deposit is located approximately 100km south of Shenyang at 40 0 59'N and 123 0 30'E

Preliminary discussion on deep-sourced uranium metallogenesis and deep prospecting

International Nuclear Information System (INIS)

Huang Shijie

2006-01-01

Prospecting for hydrothermal type uranium deposits should be aimed at medium-to large-sized deposits, and be guided by mantle-sourced, superimposed, deep-sourced metallogenic theory and the establishment of a multifactor, composite, deep-sourced metallogenic model. The author suggests that hydrothermal uranium deposits may be classified into three genetic types, i.e. hydrothermal circulation concentration, postmagmatic hydrothermal and mantle fluid concentration. These types of uranium deposits are characterized by their own metallogenic features and are concentrated in the same mineralization-concentrated area forming a metallogenic series. Large-sized uranium ore fields and rich-large uranium deposits are usually closely associated with mantle-sourced metallogenesis and the formation of such uranium ore fields and deposits is characterized by specific and unique regional geologic environments. Recognition criteria of mantle-sourced metallogenesis are preliminarily proposed in the paper. It is pointed out that prospecting in the future should follow the metallogenic model proper for the specific genetic type, and the establishment of operable prospecting model to realize the model-guided prospecting. (authors)

Uranium price forecasting methods

International Nuclear Information System (INIS)

Fuller, D.M.

1994-01-01

This article reviews a number of forecasting methods that have been applied to uranium prices and compares their relative strengths and weaknesses. The methods reviewed are: (1) judgemental methods, (2) technical analysis, (3) time-series methods, (4) fundamental analysis, and (5) econometric methods. Historically, none of these methods has performed very well, but a well-thought-out model is still useful as a basis from which to adjust to new circumstances and try again

Uranium and thorium determination in water samples taken along River Kura

International Nuclear Information System (INIS)

Ahmadov, M.M.; Ibadov, N.A.; Safarova, K.S.; Humbatov, F.Y.; Suleymanov, B.A.

2014-01-01

Full text : In the present investigation, uranium and thorium concentration in rivers water of Azerbaijan has been measured using inductively coupled plasma mass spectrometry. The Agilent 7700x series ICP-MS applied for analysis of water samples. This method is based on direct introduction of samples, without any chemical pre-treatment, into an inductively coupled plasma plasma mass spectrometer. Uranium and thorium was determined at the mass mass numbers of 238 and 232 respectively using Bi-209 as internal standard. The main purpose of the study is to measure the level of uranium and thorium in water samples taken along river Kura

Moving to world's best uranium address

International Nuclear Information System (INIS)

Noakes, Frank

2006-01-01

Most exploration dollars spent in South Australia are focused on exploiting uranium. This is for good reason as South Australia is the world's best address for uranium. Pressure to cut CO 2 emissions and the ballistic growth of the Chinese and Indian economies has heightened expectations that the worldwide use of uranium for power generation will mushroom beyond its current 17% market share. The recent Australia-China deal only seems to confirm this; hence uranium's growing popularity among miners and explorers. Such is the attractiveness of uranium-related floats, when Toro Energy sought $18m in March it was swamped with more than three times share application volume. In the north west, Southern Gold and Hindmarsh Resources are expectantly drilling for commercial uranium deposits all around the acreage that hosts the Challenger gold mine in the Gawler Craton. The first exploration drilling for uranium in quaternary-age river channels will take place in South Australia's far north in May. Red Metal says while older and deeper tertiary river channels in the area that host the Beverley uranium mine were explored for uranium, the younger near-surface channel has not had a single hole drilled for uranium. This is despite the area being one of the 'hottest radiogenic terrains in South Australia'. The company will target calcrete-style uranium mineralisation similar to the Yerrlirrie deposit in Western Australia (52,000t U308). Tasman Resources will start drilling to test seven uranium targets within 30km of Olympic Dam, the world's largest known uranium deposit, later this year. Tasman also holds tenements adjoining the Warrior uranium deposit near Tarcoola that contains known radiometric anomalies within the 40km-long Wynbring paleochannels. They are the fourth largest uranium explorer in South Australia. Alliance Resources and its JV partner Quasar Resources are exploring the Beverley 4 Mile uranium prospect at Arkaroola. Quasar is an affiliate of Heathgate Resources

The uranium resources and production of Namibia

International Nuclear Information System (INIS)

Palfi, A.G.

1997-01-01

The promulgation of the Minerals (Prospecting and Mining) Act, 1992, on 1 April 1994 and the simultaneous repeal of restrictive South African legislation on reporting uranium exploration and production results, allowed the Namibian Government for the first time to present information for publication of the report ''Uranium 1995 - Resource, Production and Demand'', by the OECD Nuclear Energy Agency and the IAEA. Namibia, one of the youngest independent nations in Africa, has a large number of uranium occurrences and deposits in several geological environments. The total estimated uranium resource amounts to about 299 thousand tonnes recoverable uranium at a cost of less than US$ 130/kg U, within the known conventional resources category. The most prominent geological type of these is the unique, granite-related uranium occurrences located in the central part of the Namib Desert. Permo-Triassic age Karoo sandstone-hosted uranium deposits were subject to only limited exploration due to the down-turn of uranium prices in the latter part of 1980s, despite they very encouraging exploration results. As only limited Karoo sandstone-covered areas were tested there is still great potential for further discoveries. The planned output of Roessing Uranium Mine at 40,000 tonnes of ore per day which results in an annual production of 4536 tonnes of uranium oxide, was achieved in 1979. In case of improved uranium market conditions, Namibia is in a strong position to increase uranium production and open up new production centres to strengthen the country's position as an important uranium producer in the world. 6 figs, 2 tabs

Uranium conversion

International Nuclear Information System (INIS)

Oliver, Lena; Peterson, Jenny; Wilhelmsen, Katarina

2006-03-01

FOI, has performed a study on uranium conversion processes that are of importance in the production of different uranium compounds in the nuclear industry. The same conversion processes are of interest both when production of nuclear fuel and production of fissile material for nuclear weapons are considered. Countries that have nuclear weapons ambitions, with the intention to produce highly enriched uranium for weapons purposes, need some degree of uranium conversion capability depending on the uranium feed material available. This report describes the processes that are needed from uranium mining and milling to the different conversion processes for converting uranium ore concentrate to uranium hexafluoride. Uranium hexafluoride is the uranium compound used in most enrichment facilities. The processes needed to produce uranium dioxide for use in nuclear fuel and the processes needed to convert different uranium compounds to uranium metal - the form of uranium that is used in a nuclear weapon - are also presented. The production of uranium ore concentrate from uranium ore is included since uranium ore concentrate is the feed material required for a uranium conversion facility. Both the chemistry and principles or the different uranium conversion processes and the equipment needed in the processes are described. Since most of the equipment that is used in a uranium conversion facility is similar to that used in conventional chemical industry, it is difficult to determine if certain equipment is considered for uranium conversion or not. However, the chemical conversion processes where UF 6 and UF 4 are present require equipment that is made of corrosion resistant material

Mineralization mechanism and geodynamic setting of No. 337 deposit in Xiazhuang uranium orefield

International Nuclear Information System (INIS)

Zhang Zhanshi; Wu Jianhua; Liu Shuai; Hua Renmin

2009-01-01

Uranium deposit No.337 in Xiazhuang uranium orefield has been regarden as a representative of the earliest forming, relatively high temperature and short time gap between the formation of pluton and the mineralization. But the latest study revealed that the formation age of the Maofeng pluton, which is the most important uranium host granite in Xiazhuang uranium orefield, is 206-238.2 Ma by LA-ICP-MS zircon dating, while the secondary origin muscovite in Maofeng pluton has the age of 131-136 Ma by 40 Ar/ 39 Ar dating which correspond to the main mineralization age of 130.3-138 Ma in uranium deposit No.337. In Guidong granitic complex, Maofeng pluton shown some unique characteristics. It has the Al 2 O 3 /TiO 2 ratio that infers the lowest forming temperature, the lowest ΣREE and it is the only pluton which presents typical tetrad effects of REE, it is also shown a varying δ 18 O values and the lowest( 87 Sr/ 86 Sr) i values. According to the above findings, a concept model of uranium mineralization and geodynamic setting for No.337 uranium deposit might be presented: in late or post-collision stage of Indosinian orogeny, strongly peraluminous granite of Maofeng pluton formed from partial melting of uranium rich formations. Intrusion of maficdyke in late Yanshanian Period(<140 Ma), caused large fluid movement. Uranium was reactivated and extracted from the altered granite,and precipitated in some favorite places to form uranium ore bodies. Uranium deposit No.337 is the typical representative of the first stage uranium mineralization in Xiazhuang uranium orefield. (authors)

Test operation of the uranium ore processing pilot plant and uranium conversion plant

International Nuclear Information System (INIS)

Suh, I.S.; Lee, K.I.; Whang, S.T.; Kang, Y.H.; Lee, C.W.; Chu, J.O.; Lee, I.H.; Park, S.C.

1983-01-01

For the guarantee of acid leaching process of the Uranium Ore Processing Pilot Plnat, the KAERI team performed the test operation in coorperation with the COGEMA engineers. The result of the operation was successful achieving the uranium leaching efficiency of 95%. Completing the guarentee test, a continuous test operation was shifted to reconform the reproducibility of the result and check the functions of every units of the pilot plant feeding the low-grade domestic ore, the consistency of the facility was conformed that the uranium can easily be dissolved out form the ore between the temperature range of 60degC-70degC for two hours of leaching with sulfuric acid and could be obtained the leaching efficiency of 92% to 95%. The uranium recovery efficiencies for the processes of extraction and stripping were reached to 99% and 99.6% respectively. As an alternative process for the separation of solid from the ore pulp, four of the Counter Current Decanters were shifted replacing the Belt Filter and those were connected in a series, which were not been tested during the guarantee operation. It was found out that the washing efficiencies of the ore pulp in each tests for the decanters were proportionally increased according to the quantities of the washing water. As a result of the test, it was obtained that washing efficiencies were 95%, 85%, 83% for the water to ore ratio of 3:1, 2:1, 1.5:1 respectively. (Author)

Machining of uranium and uranium alloys

International Nuclear Information System (INIS)

Morris, T.O.

1981-01-01

Uranium and uranium alloys can be readily machined by conventional methods in the standard machine shop when proper safety and operating techniques are used. Material properties that affect machining processes and recommended machining parameters are discussed. Safety procedures and precautions necessary in machining uranium and uranium alloys are also covered. 30 figures

Evaluation of the LASL automated spectrophotometer for uranium determination at submilligram levels

International Nuclear Information System (INIS)

Hollen, R.M.; Jackson, D.D.; Rein, J.E.

1977-07-01

The LASL automated spectrophotometer, designed for determination of 1 to 14 mg of uranium and 0.5 to 14 mg of plutonium, has been evaluated for determination of lower levels of uranium to 0.12 mg. The essentially linear response of absorbance is maintained and the standard deviation for a single measurement is constant at about 0.013 mg of uranium, corresponding to a maximum uncertainty of about 10 percent at the 0.12-mg limit. The instrument was applied to the analysis of a series of low-level-concentration, 0.07- to 0.8-mg/ml uranium samples. The results were not statistically different from those obtained by a manual spectrophotometric method

Uranium recovery from slags of metallic uranium

International Nuclear Information System (INIS)

Fornarolo, F.; Frajndlich, E.U.C.; Durazzo, M.

2006-01-01

The Center of the Nuclear Fuel of the Institute of Nuclear Energy Research - IPEN finished the program of attainment of fuel development for research reactors the base of Uranium Scilicet (U 3 Si 2 ) from Hexafluoride of Uranium (UF 6 ) with enrichment 20% in weight of 235 U. In the process of attainment of the league of U 3 Si 2 we have as Uranium intermediate product the metallic one whose attainment generates a slag contend Uranium. The present work shows the results gotten in the process of recovery of Uranium in slags of calcined slags of Uranium metallic. Uranium the metallic one is unstable, pyrophoricity and extremely reactive, whereas the U 3 O 8 is a steady oxide of low chemical reactivity, what it justifies the process of calcination of slags of Uranium metallic. The calcination of the Uranium slag of the metallic one in oxygen presence reduces Uranium metallic the U 3 O 8 . Experiments had been developed varying it of acid for Uranium control and excess, nitric molar concentration gram with regard to the stoichiometric leaching reaction of temperature of the leaching process. The 96,0% income proves the viability of the recovery process of slags of Uranium metallic, adopting it previous calcination of these slags in nitric way with low acid concentration and low temperature of leaching. (author)

National Uranium Resource Evaluation: Albuquerque Quadrangle, New Mexico

International Nuclear Information System (INIS)

Green, M.W.

1982-09-01

Areas and formations within the Albuquerque 1 0 x 2 0 Quadrangle, New Mexico designated as favorable, in order of decreasing relative favorability, include: (1) the Westwater Canyon and Brushy Basin Members of the Morrison Formation; (2) the Todilto Limestone of Late Jurassic age; (3) the Dakota Sandstone of Early and Late Cretaceous age; (4) the Ojo Alamo Sandstone of Tertiary age on the eastern side of the San Juan Basin; (5) the Galisteo Formation of Tertiary age within the Hagan Basin, in the eastern part of the Albuquerque Quadrangle; and (6) the Menefee Formation of Late Cretaceous age in the eastern part of the San Juan Basin. Favorability of the Westwater Canyon and Brushy Basin is based on the presence of favorable facies and sandstone-to-shale ratios, the presence of large masses of detrital and humic organic matter in sandstone host rocks, low to moderate dip of host beds, high radioactivity of outcropping rocks, numerous uranium occurrences, and the presence of large subsurface uranium deposits. The Todilto Limestone is considered favorable because of the presence of numerous medium to small uranium deposits in association with intraformational folds and with detrital and humic organic matter. The Dakota Sandstone is considered favorable only in areas within the Grants mineral belt where Tertiary faulting has allowed movement of uranium-bearing groundwater from the underlying Morrison Formation into organic-rich sandstone in the basal part of the Dakota. The Menefee Formation is locally favorable in the area of La Ventana Mesa where the control for known uranium deposits is both structural and stratigraphic. The Ojo Alamo Sandstone and the Galisteo Formations are considered favorable because of favorable facies, the presence of organic matter and pyrite; and low- to medium-grade mineral occurrences

Uranium, depleted uranium, biological effects; Uranium, uranium appauvri, effets biologiques

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-07-01

Physicists, chemists and biologists at the CEA are developing scientific programs on the properties and uses of ionizing radiation. Since the CEA was created in 1945, a great deal of research has been carried out on the properties of natural, enriched and depleted uranium in cooperation with university laboratories and CNRS. There is a great deal of available data about uranium; thousands of analyses have been published in international reviews over more than 40 years. This presentation on uranium is a very brief summary of all these studies. (author)

Uranium series disequilibrium: Concepts and applications

International Nuclear Information System (INIS)

Ivanovich, M.

1994-01-01

During the past four decades it has been recognized that natural disruption of the U and Th decay chains, resulting in the separation of parent and daughter nuclides, occurs as a consequence of geochemical processes acting in the near-surface environment. This realization has lead to a rapid growth in the application of the naturally occurring radioactive disequilibria diversifying broadly to touch upon a wide spectrum of problems in earth sciences. This paper is a brief review of the subject and addresses a number of issues concerning (1) physico-chemical processes responsible for fractionation of radionuclides in the decay series, (2) the range of observed radioactive disequilibrium in nature, (3) implications in terms of relative mobilities of U, Th, Ra and their daughters in the geosphere, and (4) examples of the application of these concepts to studies of paleoclimate, dating of old groundwaters, and rock/water interaction processes. This review concludes that the concept of radioactive disequilibrium in naturally occurring decay series is a powerful isotopic tool with applications in both terrestrial and marine environments over timescales of up to one million years. (orig.)

Recent activities and trend in the uranium market

International Nuclear Information System (INIS)

Kwasny, R.; Aul, F.; Lohrey, K.

2007-01-01

Concerns about the impact of hydrocarbon use on climate and global warming are significantly growing. Furthermore, we are all well aware that security of supply is increasingly an issue. In this context, it is now principally recognised that nuclear energy has to be back on the agenda. All in all, the prospects for the nuclear power industry and thus for the uranium activities is very positive for the coming years. The changes that have taken place in the international uranium market during the past several years are remarkable. Since 2002, the uranium prices have increased more than tenfold. The spot market price of uranium began an increase from about USD 9/lb U 3 O 8 in mid 2001 following a fire at the Olympic Dam mill (Australia) in October 2001 and was propelled in subsequent years by a series of interrupting events, such as the mine shaft flooding at the McArthur River mine (Canada) in April 2003, the threat of the early shutdown of the Roessing mine (Namibia) and the Ranger mine (Australia) in 2003, the decision of Techsnabexport (Tenex, Russia) in October 2003 to terminate sales of UF6 to the US trading company Globe Nuclear Services and Supply GNSS Ltd. (GNSS), and finally the complete flooding at the developing Cigar Lake mine (Canada) in October 2006. With the emergence of hedge funds and investors, that began in late 2004, increased uranium demand and upward pressure on market prices were further stimulated. What about the recent events and trends in the uranium industry? Are the uranium producers and the utilities well prepared to meet all the challenges associated with developments in the uranium business? And what about the risks, uncertainties and other factors that could affect the developments in the uranium industry and uranium markets? (orig.)

Geological and geochemical aspects of uranium deposits: a selected, annotated bibliography. [474 references

Energy Technology Data Exchange (ETDEWEB)

Thomas, J.M.; Garland, P.A.; White, M.B.; Daniel, E.W.

1980-09-01

This bibliography, a compilation of 474 references, is the fourth in a series compiled from the National Uranium Resource Evaluation (NURE) Bibliographic Data Base. This data base was created for the Grand Junction Office of the Department of Energy's National Uranium Resource Evaluation Project by the Ecological Sciences Information Center, Oak Ridge National Laboratory. The references in the bibliography are arranged by subject category: (1) geochemistry, (2) exploration, (3) mineralogy, (4) genesis of deposits, (5) geology of deposits, (6) uranium industry, (7) geology of potential uranium-bearing areas, and (8) reserves and resources. The references are indexed by author, geographic location, quadrangle name, geoformational feature, and keyword.

Uranium exploration planning and strategy

International Nuclear Information System (INIS)

Smith, A.Y.; Tauchid, M.

1991-01-01

A country may decide to begin uranium exploration for any of the following three reasons: 1. To meet the needs of a domestic nuclear power programme; 2. To supply uranium as a commodity to the world market in order to earn foreign exchange; 3. To acquire national information on the country's mineral resource planning. In any of these cases, a country must make some basic decisions regarding the means and modes whereby the uranium exploration will be carried out - by national organizations exclusively; by state organizations in joint venture with outside interests by foreign interests under the control of national regulations. Most uranium exploration is carried out following an exploration strategy in which the programme is divided into a series of steps or stages. Each of the phases is designed to eliminate areas of low potential to contain uranium deposits, while focusing attention on areas of higher potential that will be explored in greater detail at higher cost in the subsequent phase. The methods used in each phase are selected to provide the maximum information at the minimum cost so that at the end of each phase a decision can be made whether to continue to the next phase of stop. Because uranium exploration is a high cost high risk activity, governments must make decisions at the outset whether they wish to carry our the work alone and whether they can support the costs involved, or whether they wish to attract foreign investors to help absorb the costs and therefore the risks. In either case, major policy decisions are required to be made to establish the legal and fiscal environment in which the programm will be carried out. (author). 4 refs, 4 figs

Study of the age of uranium-containing mineral deposits in the Limouzat, the bois-noir mountains (12963)

International Nuclear Information System (INIS)

Durand, G.

1963-01-01

The present work is concerned with 7 different samples taken at various levels in the Limouzat mine in the Bois-Noirs mountains. It has been possible to show that the uranium dates from 265 M.Y. and that a rearrangement occurred 65 M.Y. ago. A γ-spectrometer study which was originally intended to show the existence of the lack of balance in the radon circulation, has made it possible to show that the γ spectra recorded on various samples could be erroneous. We observed in effect that the presence of lead, iron, etc., had a strong influence on the γ spectrum of the radium family, whereas all research workers have considered that concentrations in the uranium ore were negligible and had no significant effect on the study of the γ spectra of the samples. It is obvious that an interesting study has to be undertaken on the screen effects of the different cations existing in the ores. We believe that it is possible to show the presence of certain elements directly by γ-spectrometry. The ages measured with the mass spectrometer present two types of disagreement but these have been explained by considering that there occurred a first arrival of lead followed by a rearrangement and, at certain points, a second arrival at this date. Finally, the deposit studied undergoes a circulation of uranium and of radon. (author) [fr

Geochemical connection of uranium with scattered organic matter components in clay of the Maikop series (Western-Kuban foredeep)

International Nuclear Information System (INIS)

Mityushin, M.V.; Filonov, V.A.

1975-01-01

A study of a core sample of maikop clays showed that in a homogeneous stratum of maikop clays in the western Kuban depression there is a considerable variation in the uranium content (from 0.2 to 11.9x10 -4 %). The average uranium content of the clays investigated is 4.7x10 -4 %. The average content of Csub(org) for the clay samples investigated is 1.36% (Clark value 0.8%). When the data for the U and Csub(org) content of maikop clays were compared, a good correlation was found between these components (γ=0.82). This dependence is well in agreement with the data in the literature. The material presented and considered in the article permits the following conclusions: 1. A geochemical link is shown between uranium and the components of the dispersed organic substance in the clays of the maikop deposits of the western Kuban depression; 2. A direct correlative link is established between uranium and the Csub(org) of alcohol-benzol bitumoid DSBB (A) as a result of the presence of asfaltenes - polycyclic compounds where the uranium is in the form of a metallo-organic complex; 3. No direct correlational dependence is established between uranium and the alcohol-benzol bitumoid DSBB (S). Uranium was determined by the luminescence method, Csub(org) by the gasometric method with a Wirtz-Strohlein burette; the alcohol-benzol bitumoid DSBB (A) was extracted with chloroform and alcohol-benzol consecutively, and DSBB (S) with alcohol-benzol. (E.G.)

Nonlinear estimation of weathering rate parameters for uranium in surface soil near a nuclear facility

International Nuclear Information System (INIS)

Killough, G.G.; Rope, S.K.; Shleien, B.; Voilleque, P.G.

1999-01-01

A dynamic mass-balance model has been calibrated by a nonlinear parameter estimation method, using time-series measurements of uranium in surface soil near the former Feed Materials Production Center (FMPC) near Fernald, Ohio, USA. The time-series data, taken at six locations near the site boundary since 1971, show a statistically significant downtrend of above-background uranium concentration in surface soil for all six locations. The dynamic model is based on first-order kinetics in a surface-soil compartment 10 cm in depth. Median estimates of weathering rate coefficients for insoluble uranium in this soil compartment range from about 0.065-0.14 year -1 , corresponding to mean transit times of about 7-15 years, depending on the location sampled. The model, calibrated by methods similar to those discussed in this paper, has been used to simulate surface soil kinetics of uranium for a dose reconstruction study. It was also applied, along with other data, to make confirmatory estimates of airborne releases of uranium from the FMPC between 1951 and 1988. Two soil-column models (one diffusive and one advective, the latter similar to a catenary first-order kinetic box model) were calibrated to profile data taken at one of the six locations in 1976. The temporal predictions of the advective model approximate the trend of the time series data for that location. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

Sediment residence times constrained by uranium-series isotopes: A critical appraisal of the comminution approach

Science.gov (United States)

Handley, Heather K.; Turner, Simon; Afonso, Juan C.; Dosseto, Anthony; Cohen, Tim

2013-02-01

Quantifying the rates of landscape evolution in response to climate change is inhibited by the difficulty of dating the formation of continental detrital sediments. We present uranium isotope data for Cooper Creek palaeochannel sediments from the Lake Eyre Basin in semi-arid South Australia in order to attempt to determine the formation ages and hence residence times of the sediments. To calculate the amount of recoil loss of 234U, a key input parameter used in the comminution approach, we use two suggested methods (weighted geometric and surface area measurement with an incorporated fractal correction) and typical assumed input parameter values found in the literature. The calculated recoil loss factors and comminution ages are highly dependent on the method of recoil loss factor determination used and the chosen assumptions. To appraise the ramifications of the assumptions inherent in the comminution age approach and determine individual and combined comminution age uncertainties associated to each variable, Monte Carlo simulations were conducted for a synthetic sediment sample. Using a reasonable associated uncertainty for each input factor and including variations in the source rock and measured (234U/238U) ratios, the total combined uncertainty on comminution age in our simulation (for both methods of recoil loss factor estimation) can amount to ±220-280 ka. The modelling shows that small changes in assumed input values translate into large effects on absolute comminution age. To improve the accuracy of the technique and provide meaningful absolute comminution ages, much tighter constraints are required on the assumptions for input factors such as the fraction of α-recoil lost 234Th and the initial (234U/238U) ratio of the source material. In order to be able to directly compare calculated comminution ages produced by different research groups, the standardisation of pre-treatment procedures, recoil loss factor estimation and assumed input parameter values

International Uranium Resources Evaluation Project (IUREP) orientation phase mission summary report: Cameroon

International Nuclear Information System (INIS)

1985-01-01

A report has recently been published which describes the findings of the International Uranium Resources Evaluation Project (IUREP) Mission to Cameroon. The IUREP Orientation Phase Mission to Cameroon estimates the Speculative Resources of that country to be in the order of 10 000 tonnes uranium for syenite-associated U-deposits in southern Cameroon, and in the order of 5 000 tonnes uranium for uranium deposits associated with albitized and desilicified late tectonic Panafrican granites (episyenite) and Paleozoic volcanics in northern Cameroon. No specific tonnage is given for Francevillian equivalents (DJA-Series) and for Mesozoic and Cenozoic sedimentary basins, which are thought to hold limited potential for sandstone hosted uranium. However the Douala basin, consisting of mixed marine and continental sequences merits some attention. No specific budget and programme for uranium exploration are proposed for Cameroon. Instead specific recommendations concerning specific potential environments and general recommendation concerning the methodology of exploration are made. (author)

Khanneshin uranium deposit at the carbonatite volcano margin (Afghanistan)

International Nuclear Information System (INIS)

Pakul'nis, G.V.; Komarnitskij, G.M.

1995-01-01

Results of investigation of the Khanneshin uranium deposit (Afghanistan) are presented. It is shown that this deposit is the first example of true uranium mineralization, related with carbonatities, which doesn't contain thorium, titanium, niobium. The deposit is of early-quaternary age and is presented by uranyl-silicate minerals. Minerals and rocks, composing the deposit are described. Attention is paid to geochemical aspects of uranium mineralization. 6 refs.; 6 figs

Process for continuous production of metallic uranium and uranium alloys

Science.gov (United States)

Hayden, Jr., Howard W.; Horton, James A.; Elliott, Guy R. B.

1995-01-01

A method is described for forming metallic uranium, or a uranium alloy, from uranium oxide in a manner which substantially eliminates the formation of uranium-containing wastes. A source of uranium dioxide is first provided, for example, by reducing uranium trioxide (UO.sub.3), or any other substantially stable uranium oxide, to form the uranium dioxide (UO.sub.2). This uranium dioxide is then chlorinated to form uranium tetrachloride (UCl.sub.4), and the uranium tetrachloride is then reduced to metallic uranium by reacting the uranium chloride with a metal which will form the chloride of the metal. This last step may be carried out in the presence of another metal capable of forming one or more alloys with metallic uranium to thereby lower the melting point of the reduced uranium product. The metal chloride formed during the uranium tetrachloride reduction step may then be reduced in an electrolysis cell to recover and recycle the metal back to the uranium tetrachloride reduction operation and the chlorine gas back to the uranium dioxide chlorination operation.

Process for continuous production of metallic uranium and uranium alloys

Science.gov (United States)

Hayden, H.W. Jr.; Horton, J.A.; Elliott, G.R.B.

1995-06-06

A method is described for forming metallic uranium, or a uranium alloy, from uranium oxide in a manner which substantially eliminates the formation of uranium-containing wastes. A source of uranium dioxide is first provided, for example, by reducing uranium trioxide (UO{sub 3}), or any other substantially stable uranium oxide, to form the uranium dioxide (UO{sub 2}). This uranium dioxide is then chlorinated to form uranium tetrachloride (UCl{sub 4}), and the uranium tetrachloride is then reduced to metallic uranium by reacting the uranium chloride with a metal which will form the chloride of the metal. This last step may be carried out in the presence of another metal capable of forming one or more alloys with metallic uranium to thereby lower the melting point of the reduced uranium product. The metal chloride formed during the uranium tetrachloride reduction step may then be reduced in an electrolysis cell to recover and recycle the metal back to the uranium tetrachloride reduction operation and the chlorine gas back to the uranium dioxide chlorination operation. 4 figs.

Direct dating of fossils by the helium-uranium method

International Nuclear Information System (INIS)

Schaeffer, O.A.

1967-01-01

The He-U method has been found to be applicable to the dating of fossil carbonates. This method furnishes a new dating technique particularly applicable to the Pleistocene and the Tertiary periods, especially the Late Tertiary, for which other methods of age dating either fail or are difficult to correlate with the fossil record. The method has been checked for possible losses of helium and uranium from or to the surroundings. It has been found that, while a calcite lattice does not appear to retain helium, if the lattice is aragonite there is good evidence that helium leakage is not a problem. This is true at least for times up to 20 m. y. For corals where the uranium is apparently uniformly distributed within the lattice as a trace element, the uranium does not exchange or undergo concentration changes. As a result aragonite corals yield reliable He-U ages. On the other hand, the uranium in mollusc fossils is apparently mainly in the grain boundaries and is not always a tight system as far as uranium exchange or concentration changes are concerned. To obtain a reliable age for a mollusc one needs additional evidence to ensure lack of changes in uranium concentration. If the measurement of U and He is combined with 238 U, 234 U and 230 Th determinations, it appears that many mollusc shells will also be datable by the method. The resulting evidence for secular equilibrium in the 238 U chain is good evidence for a closed system as far as U concentration changes are concerned. (author)

Uranium deposits of the Commonwealth of Independent States: Principal economic-genetic types and their distribution

International Nuclear Information System (INIS)

Laverov, N.P.; Velichkin, V.I.; Shumilin, M.V.

1992-01-01

For the first time, an uncensored overview of the main economic-genetic types of uranium deposits in the countries of the former Soviet Union can be presented. The uranium regions are briefly characterized and the characteristic features and conditions of formation of the most important deposits are discussed. Eight types of deposits are described, of which those of the endogenic series (deep metasomatic and hydrothermal) contain about 60% of the total reserves of 1.2 million tons and those of the exogenic series (mostly sandstone deposits related to stratal oxidation) contain about 40%. These appear to have been five main examples of uranium mineralization, with primarily endogenic deposits formed in the early Proterozoic through Mesozoic epochs and primarily exogenic deposits in the Cenozoic epoch. 27 refs., 7 figs., 2 tabs

Harnessing redox activity for the formation of uranium tris(imido) compounds

Science.gov (United States)

Anderson, Nickolas H.; Odoh, Samuel O.; Yao, Yiyi; Williams, Ursula J.; Schaefer, Brian A.; Kiernicki, John J.; Lewis, Andrew J.; Goshert, Mitchell D.; Fanwick, Phillip E.; Schelter, Eric J.; Walensky, Justin R.; Gagliardi, Laura; Bart, Suzanne C.

2014-10-01

Classically, late transition-metal organometallic compounds promote multielectron processes solely through the change in oxidation state of the metal centre. In contrast, uranium typically undergoes single-electron chemistry. However, using redox-active ligands can engage multielectron reactivity at this metal in analogy to transition metals. Here we show that a redox-flexible pyridine(diimine) ligand can stabilize a series of highly reduced uranium coordination complexes by storing one, two or three electrons in the ligand. These species reduce organoazides easily to form uranium-nitrogen multiple bonds with the release of dinitrogen. The extent of ligand reduction dictates the formation of uranium mono-, bis- and tris(imido) products. Spectroscopic and structural characterization of these compounds supports the idea that electrons are stored in the ligand framework and used in subsequent reactivity. Computational analyses of the uranium imido products probed their molecular and electronic structures, which facilitated a comparison between the bonding in the tris(imido) structure and its tris(oxo) analogue.

Uranium content and fission track ages of some basalts from the FAMOUS area

International Nuclear Information System (INIS)

Storzer, Dieter; Selo, Madeleine

1976-01-01

The uranium contents of basalts from the rift valley in the Atlantic ocean near 37 deg N range between 75 ppb and 450 ppb. The fission track ages of these basalts range between 3x10 3 years and 6x10 5 years. They increase with distance from the axis of the median valley. Therefore, the locus of accretion of new crust seems to be restricted to a relatively narrow zone along the valley floor. In addition, the ages indicate that during the last 10 5 years the rate of accretion has been slower to the west than to the east. This indicates a migration of the active spreading center to the west by at least 1 km. the sea-floor spreading rates are high, up to 9cm/year, near the center of actual magmatic activity. They decrease with distance from the valley axis to 0.7 cm/year at about 2 km in the west respectively 1.5 cm/year at about 4 km in the east

Sedimentary uranium occurrences in Eastern Europe with special reference to sandstone formations

International Nuclear Information System (INIS)

Barthel, F.; Hahn, L.

1985-01-01

Sedimentary uranium deposits, especially in sandstones, play an important role in uranium mining in Eastern Europe. The paper reviews recent publications on uranium occurrences in sandstone formations in the German Democratic Republic, Poland, CSSR, Hungary, Romania, Bulgaria and Albania. The uranium deposits in sandstones in Yugoslavia are described in a separate paper in this volume. Sandstone deposits of the USSR are not reviewed. Uranium mineralizations occur in sandstones from Ordovician to Tertiary age. Major deposits are developed in Upper Carboniferous sandstones in association with coal (GDR, Poland), in Permian strata (CSSR, Hungary, Romania), in Cretaceous sandstones (GDR, CSSR), and in Tertiary sediments (CSSR). The Permian deposits can be compared with deposits of similar age in Northern Italy and Northern Yugoslavia. Roll-type orebodies are developed in some of the Cenomanian sandstones. Tertiary deposits are mainly associated with lignites. Uranium deposits in sandstones of Albania and Bulgaria are not described in the literature. Geologic similarities with sandstone basins in adjacent countries suggest the presence of uranium mineralizations in Permian, Lower Triassic, and Tertiary sandstones. (author)

Study of a proposed method of uranium concentration determination using low-energy γ-ray spectroscopy

International Nuclear Information System (INIS)

Rossiter, K.G.; Tang, J.C.N.

1980-01-01

The problems associated with in-situ uranium assaying are discussed, especially in relation to the secular disequilibrium between the parent uranium and its radioactive daughters. A detailed study of the gamma-spectra of some natural uranium bearing ore and mineral samples was performed using a high resolution Ge(Li) detector. A method of spectroscopic analysis of the low energy gamma-rays of U-238 and its daughter Th-234, using a proportional counter and a series of Ross filters, was found to be feasible. The application of such a method to uranium assaying in natural ore bodies is discussed

Durability of adhesive bonds to uranium alloys, tungsten, tantalum, and thorium

International Nuclear Information System (INIS)

Childress, F.G.

1975-01-01

Long-term durability of epoxy bonds to alloys of uranium (U-Nb and Mulberry), nickel-plated uranium, thorium, tungsten, tantalum, tantalum--10 percent tungsten, and aluminum was evaluated. Significant strengths remain after ten years of aging; however, there is some evidence of bond deterioration with uranium alloys and thorium stored in ambient laboratory air

Radionuclide migration around uranium ore bodies: analogue of radioactive waste repositories. Annual report, July 1982-June 1983

International Nuclear Information System (INIS)

Airey, P.L.

1984-10-01

A number of uranium ore bodies in the Northern Territory of Australia have been evaluated as geochemical analogues of high-level radioactive waste repositories. The aim of the study is to contribute to the understanding of the scientific basis for the long-term prediction of the transport of radionuclides. Particular attention is being paid to investigations of (i) mechanisms of mobilization and subsequent retardation of uranium series nuclides following the weathering of metamorphic host rocks, (ii) the role of iron minerals in the retardation of uranium and thorium, (iii) the role of groundwater colloids in the transport of radionuclides, (iv) experimental methods for studying the time dependence of adsorption coefficients, and (v) conceptual methods for studying the effect of transport of uranium series nuclides through crystalline host rocks over geological time. The possibility of incorporating certain transuranic and fission product elements into the analogue is discussed. 29 figures, 36 tables

Automated spectrophotometer for plutonium and uranium determination

International Nuclear Information System (INIS)

Jackson, D.D.; Hodgkins, D.J.; Hollen, R.M.; Rein, J.E.

1975-09-01

The automated spectrophotometer described is the first in a planned series of automated instruments for determining plutonium and uranium in nuclear fuel cycle materials. It has a throughput rate of 5 min per sample and uses a highly specific method of analysis for these elements. The range of plutonium and uranium measured is 0.5 to 14 mg and 1 to 14 mg, respectively, in 0.5 ml or less of solution with an option to pre-evaporate larger volumes. The precision of the measurements is about 0.02 mg standard deviation over the range corresponding to about 2 rel percent at the 1-mg level and 0.2 rel percent at the 10-mg level. The method of analysis involves the extraction of tetrapropylammonium plutonyl and uranyl trinitrate complexes into 2-nitropropane and the measurement of the optical absorbances in the organic phase at unique peak wavelengths. Various aspects of the chemistry associated with the method are presented. The automated spectrophotometer features a turntable that rotates as many as 24 samples in tubes to a series of stations for the sequential chemical operations of reagent addition and phase mixing to effect extraction, and then to a station for the absorbance measurement. With this system, the complications of sample transfers and flow-through cells are avoided. The absorbance measurement system features highly stable interference filters and a microcomputer that controls the timing sequence and operation of the system components. Output is a paper tape printout of three numbers: a four-digit number proportional to the quantity of plutonium or uranium, a two-digit number that designates the position of the tube in the turntable, and a one-digit number that designates whether plutonium or uranium was determined. Details of the mechanical and electrical components of the instrument and of the hardware and software aspects of the computerized control system are provided

Old age in Polish and American tv series

Directory of Open Access Journals (Sweden)

JOANNA ANIOŁ

2013-12-01

Full Text Available The educational and socialization role of the media is not the latest novelty, however there are niches that have not been developed yet. Realizing the opinion-forming role of the mass media, which may be reflected in social behaviours, the authors of this article will analyse the content of chosen media products. The image of elderly people presented by the most popular Polish and American series will be examined. The research aims to find whether Desperate Housewives and Colours of happiness (original title: Barwy szczęścia adjust the image of old age to the social-demographic situation, which is constantly changing in the majority of countries. Does the colossus – television promote stereotypes which make age discrimination morally approved – or just the opposite – a well thought out image, shaping the recognition and respect for people in their “third age”?

International Uranium Resources Evaluation Project (IUREP) national favourability studies: Bahrain

International Nuclear Information System (INIS)

1977-11-01

Bahrain consists of limestone, sandstone and marl of Cretaceous and Tertiary ages. The potential for discoveries of uranium is very limited and thus the Speculative potential is placed in the category of less than 1000 tonnes uranium. (author)

Urinary excretion of uranium in adult inhabitants of the Czech Republic

International Nuclear Information System (INIS)

Malátová, Irena; Bečková, Věra; Kotík, Lukáš

2016-01-01

The main aim of this study was to determine and evaluate urinary excretion of uranium in the general public of the Czech Republic. This value should serve as a baseline for distinguishing possible increase in uranium content in population living near legacy sites of mining and processing uranium ores and also to help to distinguish the proportion of the uranium content in urine among uranium miners resulting from inhaled dust. The geometric mean of the uranium concentration in urine of 74 inhabitants of the Czech Republic was 0.091 mBq/L (7.4 ng/L) with the 95% confidence interval 0.071–0.12 mBq/L (5.7–9.6 ng/L) respectively. The geometric mean of the daily excretion was 0.15 mBq/d (12.4 ng/d) with the 95% confidence interval 0.12–0.20 mBq/d (9.5–16.1 ng/d) respectively. Despite the legacy of uranium mines and plants processing uranium ore in the Czech Republic, the levels of uranium in urine and therefore, also human body content of uranium, is similar to other countries, esp. Germany, Slovenia and USA. Significant difference in the daily urinary excretion of uranium was found between individuals using public supply and private water wells as a source of drinking water. Age dependence of daily urinary excretion of uranium was not found. Mean values and their range are comparable to other countries, esp. Germany, Slovenia and USA. - Highlights: • Urinary uranium content of the inhabitants was experimentally determined. • Significant difference was found between inhabitants and uranium miners. • Higher uranium urinary content was found at users of private wells. • Dependence of urinary content on the age was not found. • The mean value and range of uranium daily excretion is similar to other countries.

Natural uranium toxicology - evaluation of internal contamination in man

International Nuclear Information System (INIS)

Chalabreysse, J.

1968-01-01

After reminding the physical and chemical properties of natural uranium which might affect its toxicology, a comprehensive investigation upon natural uranium metabolism and toxicity and after applying occupational exposure standards to this particular poison, it has been determined, from accident reports and human experience reported in the related literature, a series of formulae obtained by theoretical mathematical development giving principles for internal contamination monitoring and disclosure by determining uranium in the urine of occupationally exposed individuals. An assay is performed to determine individual internal contamination according to the various contamination cases. The outlined purposes, mainly practical, required some options and extrapolations. The proposed formula allows a preliminary approach and also to determine shortly a contamination extent or to discuss the systematical urinalysis results as compared with individual radio-toxicology monitoring professional standards. (author) [fr

Innovative industry alignment at RMIT to develop skills for uranium industries

International Nuclear Information System (INIS)

Bhargava, S.K.

2010-01-01

'Full text:' RMIT University has recently introduced new teaching and research training programs on uranium processing technology at both undergraduate and postgraduate level. These programs have been implemented to improve young scientists and engineers' awareness of Australia's uranium processing industry, and to help provide future employees with improved background knowledge to the industry. The teaching program involves joint course development and lectures delivered by the leading scientists from ANSTO (Dr Suzanne Burling and Dr Chris Griffith) and Rio Tinto (Dr Stephen Grocott). This lecture series, which is offered to final year applied science and chemical engineering students, covers a range of topics and issues related to uranium processing including uranium mining, methods for chracterising uranium ores, extraction of uranium, the nuclear fuel cycle, waste and safety. The research training program involves honours and PhD students undertaking research projects on uranium mineralogy and uranium extraction. Research students are also provided with extensive training on how to conduct research safely using radioactive materials. The research programs are undertaken in RMIT's new EPA approved, low level radiation laboratory which has been dedicated to research projects on uranium processing. An extended overview of both of these new programs will be presented. This program is unique in Australia and is designed to address the issue of skill shortage in the ever growing Uranium industry world wide. International collaborators in this program will be most welcomed. (author)

International Uranium Resources Evaluation Project (IUREP) national favourability studies: Israel

International Nuclear Information System (INIS)

1977-12-01

The geology of Israel is relatively simple. Most of the country is underlain by sedimentary rocks of Secondary and Tertiary age. As far as the IAEA is aware no systematic exploration has been done for conventional type uranium deposits. Israel has no uranium deposits, and no high or low-grade uranium ores. However, there are uranium 'sources' which are mainly phosphate rock.Proven phosphate reserves in Israel are estimated at about 220 million tons in five different locations. The average uranium concentration is between 100 and 170 ppm. This makes the uranium content in the proven phosphate reserves of Israel to be about 25,000 tons. Together with the possibility of additional discoveries and on the assumption that the economic conditions for the production of both phosphate and uranium become favourable the Speculative Potential is placed in the 10,000 to 50,000 tonnes uranium category. (author)

Biosorption of uranium and lead by Streptomyces longwoodensis

International Nuclear Information System (INIS)

Friis, N.; Myers-Keith, P.

1986-01-01

Biosorption of uranium and lead by lyophilized cells of Streptomyces longwoodensis was examined as a function of metal concentration, pH, cell concentration, and culture age. Cells harvested from the stationary growth phase exhibited an exceptionally high capacity for uranium (0.44 g U/g dry weight) at pH 5. Calculated values of the distribution coefficient and separation factor indicated a strong preference of the cell mass for uranyl ions over lead ions. The specific uranium uptake was similar for the cell wall and the cytoplasmic fraction. Uranium uptake was associated with an increase in hydrogen ion concentration, and phosphorus analysis of whole cells indicated a simple stoichiometric ratio between uranium uptake and phosphorus content. It is proposed that metal ions are bound to phosphodiester residues present both in the cell wall and cytoplasmic fractions. Based on this model, it was shown that uranium accumulation exhibits a maximum at pH 4.6 that is supported by experimental data from previous investigations

Orientation geochemical survey for uranium exploration using 230Th

International Nuclear Information System (INIS)

Xia Dingliang.

1985-01-01

The distribution of 230 Th in soils, rocks and ores and its relationship with respect to uranium ore formation are discussed for its possible use in geochemical exploration for U. 230 Th, U and Ra, being members of the same decay series, are different in their geochemical behavior upon which the study is orientated. Twenty uranium deposits and occurrences located in western and southern Hunan province are tested. Geochemical data obtained are comprehensively correlated. It is suggested that 230 Th is useful not only in U-Ra disequilibrium study but also in understanding the geochemical evolution of U ores. The data aid to interpret the genesis of uranium deposits and to assess the radioactive anomalies and uranium-bearing zones. Therefore, it can be adopted as a tool for searching in deep-buried uranium ores. The field procedure is rather simple and flexible to meet any geological environment. It is easy to read out and is less influnced by any kind of interference. In case of disequilibrium caused by oxidation and reduction during the period of ore formation it still gives good indication compared with that of radiometry, radonmetry and geochemical sampling for U

Uranium Elemental and Isotopic Constraints on Groundwater Flow Beneath the Nopal I Uranium Deposit, Pena Blanca, Mexico

International Nuclear Information System (INIS)

S.J. Goldstein; M.T. Murrell; A.M. Simmons

2005-01-01

The Nopal I uranium deposit in Chihuahua, Mexico, is an excellent analogue for evaluating the fate of spent fuel, associated actinides, and fission products over long time scales for the proposed Yucca Mountain high-level nuclear waste repository. In 2003, three groundwater wells were drilled directly adjacent to (PB-1) and 50 m on either side of the uranium deposit (PB-2 and PB-3) in order to evaluate uranium-series transport in three dimensions. After drilling, uranium concentrations were elevated in all of the three wells (0.1-18 ppm) due to drilling activities and subsequently decreased to ∼5-20% of initial values over the next several months. The 234 U/ 238 U activity ratios were similar for PB-1 and PB-2 (1.005 to 1.079) but distinct for PB-3 (1.36 to 1.83) over this time period, suggesting limited mixing between groundwater from these wells over these short time and length scales. Regional groundwater wells located up to several km from the deposit also have distinct uranium isotopic characteristics and constrain mixing over larger length and time scales. We model the decreasing uranium concentrations in the newly drilled wells with a simple one-dimensional advection-dispersion model, assuming uranium is introduced as a slug to each of the wells and transported as a conservative tracer. Using this model for our data, the relative uranium concentrations are dependent on both the longitudinal dispersion as well as the mean groundwater flow velocity. These parameters have been found to be correlated in both laboratory and field studies of groundwater velocity and dispersion (Klotz et al., 1980). Using typical relationships between velocity and dispersion for field and laboratory studies along with the relationship observed from our uranium data, both velocity (1-10 n/yr) and dispersion coefficient (1E-5 to 1E-2 cm 2 /s) can be derived from the modeling. As discussed above, these relatively small flow velocities and dispersivities agree with mixing

Improvement Of The U-Th Method For Dating Of Impure Calcite Having A Large Amount Of Clay And Very Low Uranium Content

Directory of Open Access Journals (Sweden)

Samer Farkh

2015-01-01

Full Text Available Abstract The U-Th method also called series method of uranium is improved by a new experimental protocol and successfully applied to the impure calcite with uranium concentration 005 dpmg which was previously difficult to be dated accurately. Our experiments performed on 15 calcite samples taken from France and Morocco have highlighted the importance of this methodological improvement by enabling i the elimination of 100 of clay residues ii the reduction of calcite quantity necessary to the chemical manipulation from 20g to 5g iii the analysis of calcite samples poor in uranium and on the other hand rich with clay and iiii the reduction of the lower limit of the U-Th method from 10 Kyrs to 6 Kyrs. The optimization of U-Th method in this work provided a better dating of the accurate age of calcite. Thus this technique is important for the chemical analysis of stalagmite floors of different caves in the region of the Near East.

Case history of natural analogue research on sandstone type uranium occurrences, Japan

International Nuclear Information System (INIS)

Sakamaki, Y.; Kanai, Y.

1991-01-01

Previous fundamental studies on the ore genesis of uranium occurrences chiefly in Cenozoic sandstone formations in Japan, have been re-examined as the case history on natural analogue of radionuclides in high-level radioactive wastes (HLRW). Two principal mode of occurrences have been distinguished among Cenozoic uranium localities in Japan. In the Setouchi (Inland Sea) subregion, hot-spots are found in lacustrine to shallow sea facies of calm environment, corresponding to the first stage of formation of tectonic basins. As observed in Ningyo-toge and Tono area, stratabound ore bodies are generally arranged into paleo-channels. Another type of sporadic uranium indications are found within collapse basins in the 'Green-tuff' subregion, where intense volcanisms and block movements had been taken places throughout Middle miocene age. Well-developed fractures were to be favorable paths for uraniferous groundwater, as well as the suitable site for deposition of uranium. In both cases, the source material of uranium is granitic basement. Under oxidizing environment, uranium anomalies have been occasionally detected in surface- or fracture waters which passing through decomposed granite. In contrast to the behavior of uranium, one of the adequate analogues for mobile nuclides, thorium and REE are relatively immobile even under the same geologic and geochemical circumstances. In ore horizon, where reducing condition has still been kept, geochronological age of tetravalent uranium mineral is in concordance with the age of the host rock. Analysis of structural control shows that the principal factors for uranium concentration are the layout of redox front related to paleo-water tables. 234U/238U disequilibrium method has been proved to be the powerful tool for detecting mobility of uranium in the host rock throughout diagenesis and weathering process. The result of field and laboratory works on this is reported as an example. (author)

Uranium and radium geochemistry. Radioactive disequilibrium in natural waters

International Nuclear Information System (INIS)

Beaucaire, C.

1987-09-01

Rock-water interactions play a primary part in uranium-series disequilibrium either by different chemical behavior or by recoiling alpha emitting nuclei in solution. Three series of thermal water containing CO 2 (Vichy, Vals and Cezallier) and one from Lodeve uranium deposit are studied to define parameters (pH, Eh, pCO 2 , T,...) controlling studied nuclei. For U complexation by carbonates is in competition with redox conditions. Ra is coprecipitated by barium. For thermal waters keeping their deep characteristics there is a low disequilibriums 234 U- 238 U between 1 and 2. On the contrary important disequilibrium (up to 12) in Vichy Saint Yorre water are due to secondary remobilization. In the same way for these waters 234 U and 226 Ra are correlated. Then leaching is essential for the radioactive disequilibrium but alpha recoil of 234 Th is of secondary importance in this case [fr

Recovery of uranium from crude uranium tetrafluoride

Energy Technology Data Exchange (ETDEWEB)

Ghosh, S K; Bellary, M P; Keni, V S [Chemical Engineering Division, Bhabha Atomic Research Centre, Mumbai (India)

1994-06-01

An innovative process has been developed for recovery of uranium from crude uranium tetrafluoride cake. The process is based on direct dissolution of uranium tetrafluoride in nitric acid in presence of aluminium hydroxide and use of solvent extraction for removal of fluorides and other bulk impurities to make uranium amenable for refining. It is a simple process requiring minimum process step and has advantage of lesser plant corrosion. This process can be applied for processing of uranium tetrafluoride generated from various sources like uranium by-product during thorium recovery from thorium concentrate, first stage product of uranium recovery from phosphoric acid by OPPA process and off grade uranium tetrafluoride material. The paper describes the details of the process developed and demonstrated on bench and pilot scale and its subsequent modification arising out of bulky solid waste generation. The modified process uses a lower quantity of aluminium hydroxide by allowing a lower dissolution of uranium per cycle and recycles the undissolved material to the next cycle, maintaining the overall recovery at high level. This innovation has reduced the solid waste generated by a factor of four at the cost of a slightly larger dissolution vessel and its increased corrosion rate. (author). 4 refs., 1 fig., 3 tabs.

Recovery of uranium from crude uranium tetrafluoride

International Nuclear Information System (INIS)

Ghosh, S.K.; Bellary, M.P.; Keni, V.S.

1994-01-01

An innovative process has been developed for recovery of uranium from crude uranium tetrafluoride cake. The process is based on direct dissolution of uranium tetrafluoride in nitric acid in presence of aluminium hydroxide and use of solvent extraction for removal of fluorides and other bulk impurities to make uranium amenable for refining. It is a simple process requiring minimum process step and has advantage of lesser plant corrosion. This process can be applied for processing of uranium tetrafluoride generated from various sources like uranium by-product during thorium recovery from thorium concentrate, first stage product of uranium recovery from phosphoric acid by OPPA process and off grade uranium tetrafluoride material. The paper describes the details of the process developed and demonstrated on bench and pilot scale and its subsequent modification arising out of bulky solid waste generation. The modified process uses a lower quantity of aluminium hydroxide by allowing a lower dissolution of uranium per cycle and recycles the undissolved material to the next cycle, maintaining the overall recovery at high level. This innovation has reduced the solid waste generated by a factor of four at the cost of a slightly larger dissolution vessel and its increased corrosion rate. (author)

First-principles study on oxidation effects in uranium oxides and high-pressure high-temperature behavior of point defects in uranium dioxide

Science.gov (United States)

Geng, Hua Y.; Song, Hong X.; Jin, K.; Xiang, S. K.; Wu, Q.

2011-11-01

Formation Gibbs free energy of point defects and oxygen clusters in uranium dioxide at high-pressure high-temperature conditions are calculated from first principles, using the LSDA+U approach for the electronic structure and the Debye model for the lattice vibrations. The phonon contribution on Frenkel pairs is found to be notable, whereas it is negligible for the Schottky defect. Hydrostatic compression changes the formation energies drastically, making defect concentrations depend more sensitively on pressure. Calculations show that, if no oxygen clusters are considered, uranium vacancy becomes predominant in overstoichiometric UO2 with the aid of the contribution from lattice vibrations, while compression favors oxygen defects and suppresses uranium vacancy greatly. At ambient pressure, however, the experimental observation of predominant oxygen defects in this regime can be reproduced only in a form of cuboctahedral clusters, underlining the importance of defect clustering in UO2+x. Making use of the point defect model, an equation of state for nonstoichiometric oxides is established, which is then applied to describe the shock Hugoniot of UO2+x. Furthermore, the oxidization and compression behavior of uranium monoxide, triuranium octoxide, uranium trioxide, and a series of defective UO2 at 0 K are investigated. The evolution of mechanical properties and electronic structures with an increase of the oxidation degree are analyzed, revealing the transition of the ground state of uranium oxides from metallic to Mott insulator and then to charge-transfer insulator due to the interplay of strongly correlated effects of 5f orbitals and the shift of electrons from uranium to oxygen atoms.

Potential supply system for uranium based upon a crustal abundance model

International Nuclear Information System (INIS)

Chavez-Martinez, M.L.

1982-01-01

The design of a computerized system for the estimation of uranium potential supply in the US was the primary objective of this study. Once completed, this system performs for various levels of economic variables, such as prices and estimation of potential uranium supply, without requiring the appraisal by geologists, area by area, of undiscovered uranium endowment. The main components that form the system are explicit models of endowment, exploration, and production. These component models are derived from engineering and geological data, and together, they comprise the system. This system is unique in that it likes physical attributes of endowment to time series of price and production. This linkage is made by simulating the activities of the US uranium industry, activities (exploration, mine development, and production) that are involved in the transformation of endowment to potential supply

MOD-AGE - an algorithm for age-depth model construction; U-series dated speleothems case study

Science.gov (United States)

Hercman, H.; Pawlak, J.

2012-04-01

We present MOD-AGE - a new system for chronology construction. MOD-AGE can be used for profiles that have been dated by different methods. As input data, the system uses the following basic measurements: activities, atomic ratios or age, as well as depth measurement. Based on probability distributions describing the measurement results, MOD-AGE estimates the age~depth relation and its confidence bands. To avoid the use of difficult-to-meet assumptions, MOD-AGE uses nonparametric methods. We applied a Monte Carlo simulation to model age and depth values based on the real distribution of counted data (activities, atomic ratios, depths etc.). Several fitting methods could be applied for estimating the relationships; based on several tests, we decide to use LOESS method (locally weighted scatterplot smoothing). The stratigraphic correction procedure applied in the MOD-AGE program uses a probability calculus, which assumes that the ages of all the samples are correctly estimated. Information about the probability distribution of the samples' ages is used to estimate the most probable sequence that is concordant according to the superposition rule. MOD-AGE is presented as a tool for the chronology construction of speleothems that have been analyzed by the U-series method, and it is compared to the StalAge algorithm presented by D. Scholtz and D.L Hoffmann (2011). Scholtz, D., Hoffmann, D. L., 2011. StalAge - An algorithm designed for construction of speleothem age models. Quaternary Geochronology 6, 369-382.

Renal thorium and uranium excretion in non-exposed subjects: influence of age and gender

International Nuclear Information System (INIS)

Werner, E.; Roth, P.; Wendler, I.; Schramel, P.

1998-01-01

The excretion of 238 U and 232 Th was investigated by ICP-MS in a group of 30 males (mean age 41 ± 18 years, range 7 to 73 years) and 33 females (43 ± 21 years, 11 to 84 years). For the thorium excretion, the geometric mean is 34 μBq/day (SD 1.90) for the whole group, 40 μBq/day (SD 2.01) for the males and 30 μBq/day (SD 1.78) for the females. The difference between the males and females is statistically insignificant. A certain increase in the excretion was observed with increasing age but the correlation coefficient of the linear relationship is statistically insignificant. For uranium, the geometric means (SD) for the whole group, the male subgroup, and the female subgroup, in μBq/day, are 237 (2.50), 287 (2.09), and 200 (2.81). The difference between the two subgroups is statistically insignificant. The excretion increases slightly with age; the correlation coefficient of the linear relationship is statistically significant. The day-to-day fluctuations in the excretion of both Th and U are considerable. (P.A.)

Increased Concentrations of Short-Lived Decay-Series Radionuclides in Groundwaters Underneath the Nopal I Uranium Deposit at Pena Blanca, Mexico

Science.gov (United States)

Luo, S.; Ku, T.; Todd, V.; Murrell, M. T.; Dinsmoor, J. C.

2007-05-01

The Nopal I uranium ore deposit at Pena Blanca, Mexico, located at > 200 meters above the groundwater table, provides an ideal natural analog for quantifying the effectiveness of geological barrier for isolation of radioactive waste nuclides from reaching the human environments through ground water transport. To fulfill such natural analog studies, three wells (PB1, PB2, and PB3 respectively) were drilled at the site from the land surface down to the saturated groundwater zone and ground waters were collected from each of these wells through large- volume sampling/in-situ Mn-filter filtration for analyses of short-lived uranium/thorium-series radionuclides. Our measurements from PB1 show that the groundwater standing in the hole has much lower 222Rn activity than the freshly pumped groundwater. From this change in 222Rn activity, we estimate the residence time of groundwater in PB1 to be about 20 days. Our measurements also show that the activities of short-lived radioisotopes of Th (234Th), Ra (228Ra, 224Ra, 223Ra), Rn (222Rn), Pb (210Pb), and Po (210Po) in PB1, PB2, and PB3 are all significantly higher than those from the other wells near the Nopal I site. These high activities provide evidence for the enrichment of long-lived U and Ra isotopes in the groundwater as well as in the associated adsorbed phases on the fractured aquifer rocks underneath the ore deposit. Such enrichment suggests a rapid dissolution of U and Ra isotopes from the uranium ore deposit in the vadose zone and the subsequent migration to the groundwater underneath. A reactive transport model can be established to characterize the in-situ transport of radionuclides at the site. The observed change of 222Rn activity at PB1 also suggests that the measured high radioactivityies in ground waters from the site isare not an artifact of drilling operations. However, further studies are needed to assess if or to what extent the radionuclide migration is affected by the previous mining activities at

Uranium districts in South Greenland

International Nuclear Information System (INIS)

Armour-Brown, A.; Tukiainen, T.; Wallin, B.

1981-01-01

A short review is given of reconnaissance work in South Greenland. The work has demonstrated that there are areas in the Motzfeldt centre of at least 1 km 2 with continuously high radioactivity. If the uranium content of these radioactive zones are sufficiently high, then potential ore tonnages could prove to be substantial. The reconnaissance exploration has proved that uranium mineralization is widely distributed in the Narssaq-Narssarssuaq district. It is, no doubt, responsible for the high uranium values in the exploration geochemical samples. Although the size of the pitchblende occurences which have been found so far are small, the high grade of the mineralisation, the great frequency of the fracturing and the evidence for an all pervasive mineralising event over a wide area indicate that there is a good possibility of finding economic mineralisation within the Narssaq-Narssarssuaq area. The area as a whole may, perhaps, be termed a ''uranium mineral district''. As the potential targets are small, only detailed follow-up exploration will establish this. At the same time more detailed work on individual showings, and geological mapping to demonstrate the relative ages of the various petrological and mineralising events, will establish the possible origin of this uranium mineralisation. (author)

Determination of the radioactive aerosols transport coefficients generated in open pit uranium mining areas

International Nuclear Information System (INIS)

Azevedo Py Junior, D. de.

1978-01-01

The classical atmospheric transport model is applied to uranium mining operations. Among the transport parameters there is one concerned with radioactive decay, but it does not include the radioactive decay series which is the specific case for uranium. Therefore, an extension of the transport theory is developed and tested, giving results greater than the ones obtained with the classical model, as expected. (author)

Tectono-sedimentary evolution of Erlian basin since late mesozoic and sandstone-hosted uranium metallogenesis

International Nuclear Information System (INIS)

Wei Sanyuan; Qin Mingkuan; Li Yuexiang; He Zhongbo; Chen Anping; Shen Kefeng; Cao Jianying

2006-01-01

Various mineral resources in a basin are associated with its tectono-sedimentary evolution. Based on the analysis of the tectono-sedimentary evolution of Erlian basin, three evolutional stages of Erlian basin are classified, they are: the continental extensional down-faulting stage, the transitional stage from down-faulting to down-warping in Early Cretaceous, and slightly compressional differentiated uplifting-subsidence since Late Cretaceous. According to the mechanism of sandstone-hosted uranium metallogenesis it is suggested that the grey clastic rock series deposited at the stage of down-faulting down-warping transition must be the important target for uranium prospecting, and the differentiated uplifting-subsidence offers necessary conditions for sandstone-hosted uranium ore-formation. Then, types of uranium mineralization that could occur in Erlian basin are discussed, and uranium metallogenic model has been preliminarily summarized. (authors)

Analytical method of uranium (IV) and uranium (VI) in uranium ores and uranium-bearing rocks

International Nuclear Information System (INIS)

Shen Zhuqin; Zheng Yongfeng; Li Qingzhen; Zhong Miaolan; Gu Dingxiang

1995-11-01

The best conditions for keeping the original valences of uranium during the dissolution and separation procedure of geological samples (especially those micro uranium-bearing rock) were studied. With the exist of high concentration protectants, the sample was decomposed with concentration HF at 40 +- 5 degree C. The U(VI) was dissolved completely and formed stable complex UO 2 F 2 , the U(IV) was precipitated rapidly and carried by carrier. Quantitative separation was carried out immediately with suction. The decomposition of sample and separation of solid/liquid phases was completed within two minutes. After separation, the U(IV) and U(VI) were determined quantitatively with laser fluorescence or voltametry respectively according to the uranium content. The limit of detection for this method is 0.7 μg/g, RSD is 10.5%, the determinate range of uranium is 2 x 10 -6 ∼10 -1 g/g. The uranium contents and their valence state ratio were measured for more than one hundred samples of sand stone and granite, the accuracy and precision of these results are satisfactory for uranium geological research. (12 tabs.; 11 refs.)

Reduction of uranium hexafluoride to uranium tetrafluoride

International Nuclear Information System (INIS)

Chang, I.S.; Do, J.B.; Choi, Y.D.; Park, M.H.; Yun, H.H.; Kim, E.H.; Kim, Y.W.

1982-01-01

The single step continuous reduction of uranium hexafluoride (UF 6 ) to uranium tetrafluoride (UF 4 ) has been investigated. Heat required to initiate and maintain the reaction in the reactor is supplied by the highly exothermic reaction of hydrogen with a small amount of elemental fluorine which is added to the uranium hexafluoride stream. When gases uranium hexafluoride and hydrogen react in a vertical monel pipe reactor, the green product, UF 4 has 2.5g/cc in bulk density and is partly contaminated by incomplete reduction products (UF 5 ,U 2 F 9 ) and the corrosion product, presumably, of monel pipe of the reactor itself, but its assay (93% of UF 4 ) is acceptable for the preparation of uranium metal with magnesium metal. Remaining problems are the handling of uranium hexafluoride, which is easily clogging the flowmeter and gas feeding lines because of extreme sensitivity toward moisture, and a development of gas nozzel for free flow of uranium hexafluoride gas. (Author)

Uranium deposition in bones of Wistar rats associated with skeleton development.

Science.gov (United States)

Rodrigues, G; Arruda-Neto, J D T; Pereira, R M R; Kleeb, S R; Geraldo, L P; Primi, M C; Takayama, L; Rodrigues, T E; Cavalcante, G T; Genofre, G C; Semmler, R; Nogueira, G P; Fontes, E M

2013-12-01

Sixty female Wistar rats were submitted to a daily intake of ration doped with uranium from weaning to adulthood. Uranium in bone was quantified by the SSNTD (solid state nuclear track detection) technique, and bone mineral density (BMD) analysis performed. Uranium concentration as a function of age exhibited a sharp rise during the first week of the experiment and a drastic drop of 70% in the following weeks. Data interpretation indicates that uranium mimics calcium. Results from BMD suggest that radiation emitted by the incorporated Uranium could induce death of bone cells. © 2013 Elsevier Ltd. All rights reserved.

Precise coulometric titration of uranium in a high-purity uranium metal and in uranium compounds

International Nuclear Information System (INIS)

Tanaka, Tatsuhiko; Yoshimori, Takayoshi

1975-01-01

Uranium in uranyl nitrate, uranium trioxide and a high-purity uranium metal was assayed by the coulometric titration with biamperometric end-point detection. Uranium (VI) was reduced to uranium (IV) by solid bismuth amalgam in 5M sulfuric acid solution. The reduced uranium was reoxidized to uranium (VI) with a large excess of ferric ion at a room temperature, and the ferrous ion produced was titrated with the electrogenerated manganese(III) fluoride. In the analyses of uranium nitrate and uranium trioxide, the results were precise enough when the error from uncertainty in water content in the samples was considered. The standard sample of pure uranium metal (JAERI-U4) was assayed by the proposed method. The sample was cut into small chips of about 0.2g. Oxides on the metal surface were removed by the procedure shown by National Bureau of Standards just before weighing. The mean assay value of eleven determinations corrected for 3ppm of iron was (99.998+-0.012) % (the 95% confidence interval for the mean), with a standard deviation of 0.018%. The proposed coulometric method is simple and permits accurate and precise determination of uranium which is matrix constituent in a sample. (auth.)

31 CFR 540.317 - Uranium feed; natural uranium feed.

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Uranium feed; natural uranium feed... (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS General Definitions § 540.317 Uranium feed; natural uranium feed. The...

Uranium exploration

International Nuclear Information System (INIS)

De Voto, R.H.

1984-01-01

This paper is a review of the methodology and technology that are currently being used in varying degrees in uranium exploration activities worldwide. Since uranium is ubiquitous and occurs in trace amounts (0.2 to 5 ppm) in virtually all rocks of the crust of the earth, exploration for uranium is essentially the search of geologic environments in which geologic processes have produced unusual concentrations of uranium. Since the level of concentration of uranium of economic interest is dependent on the present and future price of uranium, it is appropriate here to review briefly the economic realities of uranium-fueled power generation. (author)

Uranium

International Nuclear Information System (INIS)

1982-01-01

The development, prospecting, research, processing and marketing of South Africa's uranium industry and the national policies surrounding this industry form the headlines of this work. The geology of South Africa's uranium occurences and their positions, the processes used in the extraction of South Africa's uranium and the utilisation of uranium for power production as represented by the Koeberg nuclear power station near Cape Town are included in this publication

Influence of uranium hydride oxidation on uranium metal behaviour

International Nuclear Information System (INIS)

Patel, N.; Hambley, D.; Clarke, S.A.; Simpson, K.

2013-01-01

This work addresses concerns that the rapid, exothermic oxidation of active uranium hydride in air could stimulate an exothermic reaction (burning) involving any adjacent uranium metal, so as to increase the potential hazard arising from a hydride reaction. The effect of the thermal reaction of active uranium hydride, especially in contact with uranium metal, does not increase in proportion with hydride mass, particularly when considering large quantities of hydride. Whether uranium metal continues to burn in the long term is a function of the uranium metal and its surroundings. The source of the initial heat input to the uranium, if sufficient to cause ignition, is not important. Sustained burning of uranium requires the rate of heat generation to be sufficient to offset the total rate of heat loss so as to maintain an elevated temperature. For dense uranium, this is very difficult to achieve in naturally occurring circumstances. Areas of the uranium surface can lose heat but not generate heat. Heat can be lost by conduction, through contact with other materials, and by convection and radiation, e.g. from areas where the uranium surface is covered with a layer of oxidised material, such as burned-out hydride or from fuel cladding. These rates of heat loss are highly significant in relation to the rate of heat generation by sustained oxidation of uranium in air. Finite volume modelling has been used to examine the behaviour of a magnesium-clad uranium metal fuel element within a bottle surrounded by other un-bottled fuel elements. In the event that the bottle is breached, suddenly, in air, it can be concluded that the bulk uranium metal oxidation reaction will not reach a self-sustaining level and the mass of uranium oxidised will likely to be small in relation to mass of uranium hydride oxidised. (authors)

Influence of uranium hydride oxidation on uranium metal behaviour

Energy Technology Data Exchange (ETDEWEB)

Patel, N.; Hambley, D. [National Nuclear Laboratory (United Kingdom); Clarke, S.A. [Sellafield Ltd (United Kingdom); Simpson, K.

2013-07-01

This work addresses concerns that the rapid, exothermic oxidation of active uranium hydride in air could stimulate an exothermic reaction (burning) involving any adjacent uranium metal, so as to increase the potential hazard arising from a hydride reaction. The effect of the thermal reaction of active uranium hydride, especially in contact with uranium metal, does not increase in proportion with hydride mass, particularly when considering large quantities of hydride. Whether uranium metal continues to burn in the long term is a function of the uranium metal and its surroundings. The source of the initial heat input to the uranium, if sufficient to cause ignition, is not important. Sustained burning of uranium requires the rate of heat generation to be sufficient to offset the total rate of heat loss so as to maintain an elevated temperature. For dense uranium, this is very difficult to achieve in naturally occurring circumstances. Areas of the uranium surface can lose heat but not generate heat. Heat can be lost by conduction, through contact with other materials, and by convection and radiation, e.g. from areas where the uranium surface is covered with a layer of oxidised material, such as burned-out hydride or from fuel cladding. These rates of heat loss are highly significant in relation to the rate of heat generation by sustained oxidation of uranium in air. Finite volume modelling has been used to examine the behaviour of a magnesium-clad uranium metal fuel element within a bottle surrounded by other un-bottled fuel elements. In the event that the bottle is breached, suddenly, in air, it can be concluded that the bulk uranium metal oxidation reaction will not reach a self-sustaining level and the mass of uranium oxidised will likely to be small in relation to mass of uranium hydride oxidised. (authors)

Different periods of uranium and thorium occurrence in Madagascar (1960); Cycles uraniferes et thoriferes a Madagascar (1960)

Energy Technology Data Exchange (ETDEWEB)

Moreau, M [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

1960-07-01

In Madagascar, the first typical occurrences of thorium and uranium are about 500 million years old. Previously thorium and uranium were rather concentrated in the granitic and charnockitic zones, chiefly in minerals such as monazite, apatite and zircon. At the end of the Precambrian period, metasomatic granites occur especially in the anticlinal series (Andriba orthite granite). The granitization is followed by the formation of the main pegmatitic areas in the Island with Th-U niobotantalates, uraninite and beryl. The pegmatites are well developed in the synclinal series with a poor migmatization or no migmatization at all. In the same time a large uranium and thorium province with uranothorianite deposits appears within the calcomagnesian series of the Southern part of Madagascar. Later, large amounts of monazite were carried down to the detritic Karroo sediments during tile erosion of the metamorphic precambrian rocks. Monazite has been concentrated again by frequent marine incursions, till the present time. In the medium Karroo, near Folakara, uranium minerals occur in direct relation with carbonaceous material. Finally we must note the uranium occurrence in the pleistocene carbonaceous shales of Antsirabe basin, in contact with crystalline rocks. (author) [French] A Madagascar, le premier cycle uranifere et thorifere bien caracterise se situe aux alentours de 500 millions d'annees. Auparavant, le thorium et l'uranium sont concentres de preference dans les zones granitiques et charnockites sous forme de monazite, apatite ou zircon. Vers la fin du Precambrien, se produisent des granitisations metasomatiques, surtout dans les zones anticlinales (type Andriba a orthite). La fin de cette granitisation s'accompagne de la formation des principaux champs pegmatitiques de l'Ile a niobotantalates uraniferes, uraninite et beryl, qui se developpent de preference dans les series synclinales peu ou pas migmatisees. A cette meme epoque s'individualise au sein des series

Natural uranium toxicology - evaluation of internal contamination in man; Toxicologie de l'uranium naturel - essai d'evaluation de la contamination interne chez l'homme

Energy Technology Data Exchange (ETDEWEB)

Chalabreysse, J [Commissariat a l' Energie Atomique, Pierrelatte (France). Centre d' Etudes Nucleaires

1968-07-01

After reminding the physical and chemical properties of natural uranium which might affect its toxicology, a comprehensive investigation upon natural uranium metabolism and toxicity and after applying occupational exposure standards to this particular poison, it has been determined, from accident reports and human experience reported in the related literature, a series of formulae obtained by theoretical mathematical development giving principles for internal contamination monitoring and disclosure by determining uranium in the urine of occupationally exposed individuals. An assay is performed to determine individual internal contamination according to the various contamination cases. The outlined purposes, mainly practical, required some options and extrapolations. The proposed formula allows a preliminary approach and also to determine shortly a contamination extent or to discuss the systematical urinalysis results as compared with individual radio-toxicology monitoring professional standards. (author) [French] Apres le rappel des caracteristiques physiques et des proprietes chimiques de l'uranium naturel pouvant avoir une influence sur sa toxicologie, l'etude detaillee de son metabolisme et de sa toxicite, puis l'application des normes professionnelles d'exposition au cas particulier de ce toxique, il est etabli, a partir des comptes rendus d'accidents et de l'experimentation humaine rapportes dans la litterature, une serie de formules obtenues par developpement mathematique theorique qui posent les principes de la surveillance et de la mise en evidence de la contamination interne par la recherche et le dosage de l'uranium dans les urines d'individus professionnellement exposes. Un essai d'evaluation de la contamination interne individuelle suivant les differents cas de contamination est effectue. Le formulaire propose permet de faire une premiere approximation et d'apprecier rapidement l'importance d'une contamination ou bien d'interpreter les resultats d

Uranium conversion; Urankonvertering

Energy Technology Data Exchange (ETDEWEB)

Oliver, Lena; Peterson, Jenny; Wilhelmsen, Katarina [Swedish Defence Research Agency (FOI), Stockholm (Sweden)

2006-03-15

FOI, has performed a study on uranium conversion processes that are of importance in the production of different uranium compounds in the nuclear industry. The same conversion processes are of interest both when production of nuclear fuel and production of fissile material for nuclear weapons are considered. Countries that have nuclear weapons ambitions, with the intention to produce highly enriched uranium for weapons purposes, need some degree of uranium conversion capability depending on the uranium feed material available. This report describes the processes that are needed from uranium mining and milling to the different conversion processes for converting uranium ore concentrate to uranium hexafluoride. Uranium hexafluoride is the uranium compound used in most enrichment facilities. The processes needed to produce uranium dioxide for use in nuclear fuel and the processes needed to convert different uranium compounds to uranium metal - the form of uranium that is used in a nuclear weapon - are also presented. The production of uranium ore concentrate from uranium ore is included since uranium ore concentrate is the feed material required for a uranium conversion facility. Both the chemistry and principles or the different uranium conversion processes and the equipment needed in the processes are described. Since most of the equipment that is used in a uranium conversion facility is similar to that used in conventional chemical industry, it is difficult to determine if certain equipment is considered for uranium conversion or not. However, the chemical conversion processes where UF{sub 6} and UF{sub 4} are present require equipment that is made of corrosion resistant material.

Principal types of precambrian uranium-gold deposits and their metallogenetic characteristics in China

International Nuclear Information System (INIS)

Liang Liang; Zhong Zhiyun.

1988-01-01

Principal types of Precambrian uranium-gold deposits are follows: paleo-conglomerate uranium-deposit, stratified or strata-bound uranium-gold deposit, unconformity-related uranium deposit (no or seldem gold) and greenstone gold deposit. The main types of gold deposits in China is greenstone one which is characterized by later age, high grade metamorphism and a large time difference between diagenesis of host rocks and gold metallogenesis. Gold deposits are spatially distributed in the uplift area, whereas uranium deposits are distributed in the downfaulted belt. Furthermore, both uranium and gold deposits are controlled by regional fractures

National Uranium Resource Evaluation: Providence Quadrangle, Connecticut, Rhode Island, and Massachusetts

International Nuclear Information System (INIS)

Zollinger, R.C.; Blauvelt, R.P.; Chew, R.T. III.

1982-09-01

The Providence Quadrangle, Connecticut, Rhode Island, and Massachusetts, was evaluated to a depth of 1500 m to identify environments and delineate areas favorable for uranium deposits. Criteria for this evaluation were developed by the National Uranium Resource Evaluation program. Environments were recognized after literature research, surface and subsurface geologic reconnaissance, and examination of known uranium occurrences and aeroradioactivity anomalies. Environments favorable for authigenic uranium deposits were found in the Quincy and Cowesett Granites. An environment favorable for contact-metasomatic deposits is in and around the borders of the Narragansett Pier Granite where it intrudes the Pennsylvanian sediments of the Narragansett Basin. An environment favorable for authigenic deposits in metamorphic rocks is in a migmatite on the eastern edge of the Scituate Granite Gneiss batholith. Environments favorable for contact-metasomatic deposits occur at the contacts between many of the granitic rocks and metamorphic rocks of the Blackstone Series. Results of this study also indicate environments favorable for sandstone-type uranium deposits are present in the rocks of the Narragansett Basin. Environments unfavorable for uranium deposits in the quadrangle include all granites not classified as favorable and the metamorphic rocks of eastern Connecticut. Glacial deposits and Cretaceous-Tertiary sediments remain unevaluated

IN-SITU RADIONUCLIDE TRANSPORT NEAR THE NOPAL I URANIUM DEPOSIT AT PENA BLANCA, MEXICO: CONSTRAINTS FROM SHORT-LIVED DECAY-SERIES RADIONUCLIDES

International Nuclear Information System (INIS)

Luo, S.; Ku, T.L.; Todd, V.; Murrell, M.; Pineda, J. Alfredo Rodriguez; Dinsmoor, J.; Mitchell, A.

2005-01-01

For nuclear waste management, an important mechanism by which radioactive waste components are isolated from returning to the human environment, the biosphere, is by the geological barrier in which the effectiveness of the barrier is characterized by in-situ retardation factor, i.e., the transport rate of a radionuclide relative to that of groundwater. As part of natural analog studies of the Yucca Mountain Project of the U. S. Department of Energy, we propose such characterization by using naturally-occurring decay-series radioisotopes as an analog. We collected large-volume (>1000 liters) groundwater samples from three wells (PB, Pozos, and PB4, respectively) near the Nopal I Uranium Ore site at Pena Blanca, Mexico, by using an in-situ Mn-cartridge filtration technique for analysis of short-lived decay-series radionuclides. Results show that the activities of short-lived radioisotopes ( 228 Ra, 224 Ra and 223 Ra) and activity ratios of 224 Ra/ 228 Ra and 224 Ra/ 223 Ra are higher at PB and Pozos than at PB4. In contrast, the 210 Po activity is much lower at PB and Pozos than at PB4. The high Ra activities and activities ratios at PB and Pozos are attributable to the high alpha-recoil input from the aquifer rocks, while the high 210 Po activity at PB4 is due to the enhanced colloidal transport. Based on a uranium-series transport model, we estimate that the in-situ retardation factor of Ra is (0.43 ± 0.02) x 10 3 at PB, (1.68 ± 0.08) x 10 3 at Pozos, and (1.19 ± 0.08) x 10 3 at PB4 and that the mean fracture width in the aquifer rocks is about 0.23 (micro)m at PB, 0.37 (micro)m at Posos, and 4.0 (micro)m at PB4, respectively. The large fracture width at PB4 as derived from the model provides an additional evidence to the inference from the Po measurements that particle-reactive radionuclides are transported mainly as colloidal forms through the large fractures in rocks. Our model also suggests that in addition to alpha recoil, decay of 226 Ra from the adsorbed

Uraniferous opal, Virgin Valley, Nevada: conditions of formation and implications for uranium exploration

International Nuclear Information System (INIS)

Zielinski, R.A.

1981-01-01

Fission-track radiography shows uranium to be homogeneously dispersed throughout the opal structure, suggesting coprecipitation of dissolved uranium and silica gel. Fluid inclusions preserved within opal replacements of diatomite have homogenization temperatures in the epithermal range and are of low salinity. Four samples of opal from one locality all have U-Pb apparent ages which suggest uraniferous opal precipitation in late Pliocene time. These ages correspond to a period of local, normal faulting, and high-angle faults may have served as vertical conduits for transport of deep, thermalized ground water to shallower levels. Lateral migration of rising solutions occurred at intersections of faults with permeable strata. Silica and some uranium were dissolved from silica-rich host strata of 5-20 ppm original uranium content and reprecipitated as the solutions cooled. The model predicts that in similar geologic settings, ore-grade concentrations of uranium will occur in permeable strata that intersect high-angle faults and that contain uranium source rocks as well as efficient reductant traps for uranium. In the absence of sufficient quantities of reductant materials, uranium will be flushed from the system or will accumulate in low-grade disseminated hosts such as uraniferous opal. (Auth.)

Uraniferous opal, Virgin Valley, Nevada: conditions of formation and implications for uranium exploration

Energy Technology Data Exchange (ETDEWEB)

Zielinski, R A [Geological Survey, Denver, CO (USA)

1981-01-01

Fission-track radiography shows uranium to be homogeneously dispersed throughout the opal structure, suggesting coprecipitation of dissolved uranium and silica gel. Fluid inclusions preserved within opal replacements of diatomite have homogenization temperatures in the epithermal range and are of low salinity. Four samples of opal from one locality all have U-Pb apparent ages which suggest uraniferous opal precipitation in late Pliocene time. These ages correspond to a period of local, normal faulting, and high-angle faults may have served as vertical conduits for transport of deep, thermalized ground water to shallower levels. Lateral migration of rising solutions occurred at intersections of faults with permeable strata. Silica and some uranium were dissolved from silica-rich host strata of 5-20 ppm original uranium content and reprecipitated as the solutions cooled. The model predicts that in similar geologic settings, ore-grade concentrations of uranium will occur in permeable strata that intersect high-angle faults and that contain uranium source rocks as well as efficient reductant traps for uranium. In the absence of sufficient quantities of reductant materials, uranium will be flushed from the system or will accumulate in low-grade disseminated hosts such as uraniferous opal.

Uranium/thorium dating of Late Pleistocene peat deposits in NW Europe, uranium/thorium isotope systematics and open-system behaviour of peat layers

NARCIS (Netherlands)

Heijnis, H.; Plicht, J. van der

1992-01-01

The possibility of dating peat by the uranium-series disequilibrium method is discussed. In principle, this method can be used to date peat to approximately 350 ka. The application of the U/Th disequilibrium method (UTD) on peat provides us with the probability of constructing a new chronology for

Ore-concentrating structures with telescoped uranium mineralization

International Nuclear Information System (INIS)

Shchetochkin, V.N.; Dmitriyev, V.I.; Tkachenko, I.I.

1986-01-01

Deep faults are the main controlling elements in uranium ore fields, although the immediate geologic environments may be quite varied. Within the fault zones, the uranium fields are usually associated with areas where major transverse and diagonal faults intersect or link, and with points of splitting or change in strike in disjunctive zones. Another distinctive feature of the mineralized structure is their long history, with a combination of tectonic elements differing in age and type, usually associated with retrograde dislocation metamorphism. The specific features of these structures control the uranium mineralization, which is usually localized in foci with telescoped tectonic, magmatic, hydrothermal, metasomatic, and sometimes exogenous processes. The unnamed area (in the Ukraine?) furnishes a good example of how successive stages of a complex geologic history affect the occurrence of such a highly mobile element as uranium. 12 references, 4 figures

Corrosion behavior, mechanical properties, and long-term aging of nickel-plated uranium

International Nuclear Information System (INIS)

Dini, J.W.; Johnson, H.R.; Schoenfelder, C.W.

1976-01-01

The behavior of nickel-plated uranium upon exposure to moist nitrogen was evaluated. Plating thicknesses of 0.051 mm (2 mil) were adequate to prevent corrosion. Specimens with thinner coats showed some corrosion and some reduction in mechanical properties during subsequent testing. Plated samples exposed to dry air at ambient pressure for 10 y showed no corrosion and no degradation of mechanical properties. Surface and bulk hydrogen content, as well as free hydrogen generated during the test, were measured to determine the extent of corrosion. Results support an earlier proposed mechanism for uranium corrosion at low humidities

Steps for preparing uranium production feasibility studies: A guidebook

International Nuclear Information System (INIS)

1996-06-01

Uranium exploration, development and eventual production, form a series of progressive and logical steps. Each step is part of a progression of activities with the objective of obtaining new or additional information from which a crucial decision is to be made. This guidebook is primarily aimed at mineral management personnel in developing countries who have little or no experience in preparing feasibility studies in uranium production. It is not a textbook which describes the geology, mining or processing of uranium. This guidebook deals with the philosophy, basic principles and important factors in the various stages of economic evaluation of the project. This guidebook is primarily concerned with small to medium sized mining projects. However, it can also provide useful guidance for the initial study of larger mining projects. More detailed studies of larger projects, however, should be left to well known experts in the field. While the mineral commodity in question is uranium, the procedures and approaches outlined in this guidebook are generally applicable to the study of other commodities. Refs, figs, tabs

Uranium mineralization in the Molteno and Elliot Formations

International Nuclear Information System (INIS)

Le Roux, J.P.

1990-01-01

To date very little has been published on the uranium deposits of the Molteno and Elliot Formations. Two selected deposits from these formations are described and compared to the uranium occurrences of the Beaufort Group. Whereas the latter are generally confined to channel zones due to the fine grain size and impermeable nature of the host sandstones, uranium in the Molteno and Elliot Formations seems to be concentrated in the less permeable 'island' areas. An apparent association with dolerite sills and dykes also suggests that the host sandstones were still sufficiently permeable after intrusion of the dolorite so that ground waters could remobilize the uranium. This agrees with recently published isotopic ages for the mineralization. There is a distinct possibility that roll-type uranium deposits may be present in the Molteno and Elliot Formations, and any future exploration should bear this in mind. 9 figs., 1 tab., 16 refs

Extraction of uranium from coarse ore and acid-curing and ferric sulphate-trickle leaching process

International Nuclear Information System (INIS)

Jin Suoqing

1994-01-01

On the basis of analysis of the problems in the technology of the traditional uranium hydrometallurgy and the limitations of thin layer leaching process (TLL), a new leaching system-acid-curing and ferric sulphate-trickle leaching (AFL) process (NGJ in Chinese) has developed for extraction of uranium from the coarse ore. The ferric sulphate solution was used for trickling the acid-cured uranium ore and the residual leaching reaction incomplete in TLL process can be improved in this process. And the AFL process has a wide applicability to China's uranium ores, being in competition with the traditional agitation leaching process for treating coarse ores. The uranium ore processing technology based on the AFL process will become one of the new basic technologies of uranium hydrometallurgy. A series of difficulties will be basically overcome associated with fine grinding because of its elimination in the presented process. Moreover, the situation of the present uranium hydrometallurgy can be also changed owing to without technological effluent discharge

Uranium hydrogeochemical and stream sediment reconnaissance of the thermopolis NTMS Quadrangle, Wyoming, including concentrations of forty-two additional elements

International Nuclear Information System (INIS)

Maassen, L.W.

1980-08-01

The Los Alamos Scientific Laboratory conducted a hydrogeochemical and stream sediment reconnaissance for uranium in the Thermopolis National Topographic Map Series quadrangle, Wyoming. Totals of 920 water and 1821 sediment samples were collected from 1977 locations at an average density of one sample location per 9 km 2 over an 18,000-km 2 area. Water samples were collected from streams, springs, and wells; sediment samples were collected from streams and springs. The uranium contents of water samples range from below the detection limit of 0.02 ppB to 307.98 ppB with a median of 0.56 ppB. Six clusters of anomalous water samples were delineated within the Wind River Basin and are associated predominantly with the Wind River formation. Two clusters of anomalous waters were collected on the southern margin of the Bighorn Basin and are associated with sandstone and shales of Permian through Cretaceous age. The uranium contents of sediment samples range from 0.43 to 94.65 ppM with a median of 2.90 ppM. Most sediment samples with uranium concentrations of greater than 12 ppM are underlain by Precambrian crystalline rocks of the Wind River Range; this area contains the highest uranium values found in sediments from the Thermopolis quadrangle. Other samples containing greater than 12 ppM uranium are found associated with the Wind River and Aycross formations along the northern margin of the Wind River Basin, and one sample was collected from Precambrian granitic terrain of the Owl Creek Mountains

Uranium

International Nuclear Information System (INIS)

Mackay, G.A.

1978-01-01

The author discusses the contribution made by various energy sources in the production of electricity. Estimates are made of the future nuclear contribution, the future demand for uranium and future sales of Australian uranium. Nuclear power growth in the United States, Japan and Western Europe is discussed. The present status of the six major Australian uranium deposits (Ranger, Jabiluka, Nabarlek, Koongarra, Yeelerrie and Beverley) is given. Australian legislation relevant to the uranium mining industry is also outlined

Czechoslovak uranium

International Nuclear Information System (INIS)

Pluskal, O.

1992-01-01

Data and knowledge related to the prospecting, mining, processing and export of uranium ores in Czechoslovakia are presented. In the years between 1945 and January 1, 1991, 98,461.1 t of uranium were extracted. In the period 1965-1990 the uranium industry was subsidized from the state budget to a total of 38.5 billion CSK. The subsidies were put into extraction, investments and geologic prospecting; the latter was at first, ie. till 1960 financed by the former USSR, later on the two parties shared costs on a 1:1 basis. Since 1981 the prospecting has been entirely financed from the Czechoslovak state budget. On Czechoslovak territory uranium has been extracted from deposits which may be classified as vein-type deposits, deposits in uranium-bearing sandstones and deposits connected with weathering processes. The future of mining, however, is almost exclusively being connected with deposits in uranium-bearing sandstones. A brief description and characteristic is given of all uranium deposits on Czechoslovak territory, and the organization of uranium mining in Czechoslovakia is described as is the approach used in the world to evaluate uranium deposits; uranium prices and actual resources are also given. (Z.S.) 3 figs

Uranium in Niger; L'uranium au Niger

Energy Technology Data Exchange (ETDEWEB)

Gabelmann, E

1978-03-15

This document presents government policy in the enhancement of uranium resources, existing mining companies and their productions, exploitation projects and economical outcome related to the uranium mining and auxiliary activities. [French] Le document presente la politique de l'Etat dans le cadre de la mise en valeur des ressources d'uranium, les societes minieres existantes et leurs productions, les projets d'exploitation d'uranium et les retombees economiques liees aux activites uraniferes et connexes.

Uranium-238 and thorium-232 series concentrations in soil, radon-222 indoor and drinking water concentrations and dose assessment in the city of Alameda, Chihuahua, Mexico

Energy Technology Data Exchange (ETDEWEB)

Colmenero Sujo, L.; Montero Cabrera, M.E. E-mail: elena.montero@cimav.edu.mx; Villalba, L.; Renteria Villalobos, M.; Torres Moye, E.; Garcia Leon, M.; Garcia-Tenorio, R.; Mireles Garcia, F.; Herrera Peraza, E.F.; Sanchez Aroche, D

2004-07-01

High-resolution gamma spectrometry was used to determine the concentration of {sup 40}K, {sup 238}U and {sup 232}Th series in soil samples taken from areas surrounding the city of Aldama, in Chihuahua. Results of indoor air short-time sampling, with diffusion barrier charcoal detectors, revealed relatively high indoor radon levels, ranging from 29 to 422 Bq/m{sup 3}; the radon concentrations detected exceeded 148 Bq/m{sup 3} in 76% of the homes tested. Additionally, liquid scintillation counting showed concentrations of radon in drinking water ranging from 4.3 to 42 kBq/m{sup 3}. The high activity of {sup 238}U in soil found in some places may be a result of the uranium milling process performed 20 years ago in the area. High radon concentrations indoor and in water may be explained by assuming the presence of uranium-bearing rocks underneath of the city, similar to a felsic dike located near Aldama. The estimated annual effective dose of gamma radiation from the soil and radon inhalation was 3.83 mSv.

Uranium-238 and thorium-232 series concentrations in soil, radon-222 indoor and drinking water concentrations and dose assessment in the city of Aldama, Chihuahua, Mexico.

Science.gov (United States)

Colmenero Sujo, L; Montero Cabrera, M E; Villalba, L; Rentería Villalobos, M; Torres Moye, E; García León, M; García-Tenorio, R; Mireles García, F; Herrera Peraza, E F; Sánchez Aroche, D

2004-01-01

High-resolution gamma spectrometry was used to determine the concentration of 40K, 238U and 232Th series in soil samples taken from areas surrounding the city of Aldama, in Chihuahua. Results of indoor air short-time sampling, with diffusion barrier charcoal detectors, revealed relatively high indoor radon levels, ranging from 29 to 422 Bq/m3; the radon concentrations detected exceeded 148 Bq/m3 in 76% of the homes tested. Additionally, liquid scintillation counting showed concentrations of radon in drinking water ranging from 4.3 to 42 kBq/m3. The high activity of 238U in soil found in some places may be a result of the uranium milling process performed 20 years ago in the area. High radon concentrations indoor and in water may be explained by assuming the presence of uranium-bearing rocks underneath of the city, similar to a felsic dike located near Aldama. The estimated annual effective dose of gamma radiation from the soil and radon inhalation was 3.83 mSv.

Characteristics of isotope geology of sandstone-type uranium deposit in Turpan-Hami Basin

International Nuclear Information System (INIS)

Liu Hanbin; Xia Yuliang; Lin Jinrong; Fan Guang

2003-01-01

This paper expounds the isotope characteristics of in-situ leachable sandstone-type uranium deposit of Shihongtan in the southwestern part of Turpan-Hami basin. The results suggest that uranium mineralization age of 48 ± 2 Ma and 28 ± 4 Ma are obtained. The ages of the porphyritic granite and gneissic granite from the southwestern area are 422 ± 5 Ma and 268 ± 23 Ma. The U-Pb age of clastic zircons from ore-bearing sandstone is 283 ± 67 Ma, which is corresponding to the age of gneissic granite of the provenance area indicating the material source of uraniferous sandstone.Based. The sources are uraniferous sandstone accumulated during the deposition and the uranium leached from provenance area rocks by weathering. (authors)

Uranium wars the scientific rivalry that created the nuclear age

CERN Document Server

Aczel, Amir D

2009-01-01

The author of Fermat's Last Theorem tackles the cause of the last century's most destructive event - the discovery of nuclear power. Aczel presents the fascinating story of the rival scientists who uncovered uranium's potential and reveals the ongoing tale of an element that is never far from today's headlines.

Descriptive documentation for New Mexico uranium milling model

International Nuclear Information System (INIS)

Bonem, G.; Livevano, R.J.

1981-01-01

The New Mexico Uranium Milling Model is a linear programming model. It can demonstrate how cost minimizing management can reduce the costs of milling uranium subject to a series of environmental, resource, and technological constraints. For example, if 15,000 tons were the targeted level of milling output, the model would provide the minimum cost of this production level, given certain levels of environmental, fuel, water, and technological constraints. The model was developed to allow state policymakers to assess the uranium industry from various standpoints. Through the use of the model, state policymakers can determine the effects of air and water discharge standards and limited capital availability on: milling costs of production; uses of electricity, fuel, and water; and levels of air and water emissions. The model covers the following: process technologies which are acid leach and carbonate leach; raw materials mix; air and water discharges; residual treatment process; and plant types

Radon problem in uranium industry

International Nuclear Information System (INIS)

Khan, A.H.; Raghavayya, M.

1991-01-01

Radon emission is invariably associated with the mining and processing of uranium ores. Radon (sup(222)Rn) enters mine atmosphere through diffusion from exposed ore body, fractures and fissures in the rocks and is also brought in by ground water. Being the progenitor of a series of short lived radioisotopes it contributes over 70% of the radiation dose to mine workers and thus accounts for nearly 30% of the total radiation doses received by workers in the whole nuclear industry. This paper summarises the data on radon emanation from the ore body, backfilled sands and mine water. Radon and its progeny concentrations in different haulage levels and stopes of the Jaduguda uranium mine are presented to emphasise the need for a well planned ventilation system to control radiation exposure of miners. Results of radon monitoring from a few exploratory uranium mines are included to indicate the need for a good ventilation system from inception of the mining operations. Relative contribution of mine exhaust and tailings surfaces to the environmental radon are also given. Some instruments developed locally for monitoring of radon and its progeny in mines and in the environment are briefly described to indicate the progress made in this field. (author). 17 refs., 2 figs., 6 tabs

Radionuclide migration around uranium ore bodies in the Alligator Rivers region of the Northern Territory, Australia - analogue of radioactive waste repositories

International Nuclear Information System (INIS)

Airey, P.L.; Roman, D.; Golian, C.; Short, S.; Nightingale, T.; Lowson, R.T.; Davey, B.G.; Gray, D.

1984-01-01

Appropriate geochemical analogues may be used to reduce the uncertainties in predicting the long-term transport of actinides, radium and fission products from laboratory adsorption and hydrological data. In this study the migration of uranium series nuclides within, and down-gradient of ore bodies in the Alligator Rivers uranium province of the Northern Territory of Australia is described. A mathematical framework was developed to permit calculation of the rate of leaching or deposition of uranium and radium between defined zones of the ore bodies, and the rate of loss of the nuclides due to groundwater transport and surface erosion. A detailed study was made of the distribution of uranium, thorium and radium isotopes within various minerals comprising the weathered ore assemblage. Uranium and thorium concentrate principally in the iron minerals and radium in the clay-quartz phases. Substantial disequilibria are observed, which are attributed to a combination of α-recoil and chemical effects. Evidence of the relative lability of iron phases is presented. The transport of uranium series nuclides in groundwater intersecting the deposits was investigated. Down-gradient of the Ranger One deposit, the maximum retardation factor of uranium is 250. The role of colloids in groundwater transport is being studied. Uranium is transported principally in solution. There appears to be an equilibrium between solute and articulate uranium

Uranium ores

International Nuclear Information System (INIS)

Poty, B.; Roux, J.

1998-01-01

The processing of uranium ores for uranium extraction and concentration is not much different than the processing of other metallic ores. However, thanks to its radioactive property, the prospecting of uranium ores can be performed using geophysical methods. Surface and sub-surface detection methods are a combination of radioactive measurement methods (radium, radon etc..) and classical mining and petroleum prospecting methods. Worldwide uranium prospecting has been more or less active during the last 50 years, but the rise of raw material and energy prices between 1970 and 1980 has incited several countries to develop their nuclear industry in order to diversify their resources and improve their energy independence. The result is a considerable increase of nuclear fuels demand between 1980 and 1990. This paper describes successively: the uranium prospecting methods (direct, indirect and methodology), the uranium deposits (economical definition, uranium ores, and deposits), the exploitation of uranium ores (use of radioactivity, radioprotection, effluents), the worldwide uranium resources (definition of the different categories and present day state of worldwide resources). (J.S.)

The uranium and thorium separation in the chemical reprocessing of the irradiated fuel of thorium and uranium mixed oxides

International Nuclear Information System (INIS)

Oliveira, E.F. de.

1984-09-01

A bibliographic research has been carried out for reprocessing techniques of irradiated thorium fuel from nuclear reactors. The Thorex/Hoechst process has been specially considered to establish a method for reprocessing thorium-uranium fuel from PWR. After a series of cold tests performed in laboratory it was possible to set the behavior of several parameters affecting the Thorex/Hoechst process. Some comments and suggestions are presented for modifications in the process flosheet conditions. A discussion is carried out for operational conditions such as the aqueous to organic flow ratio the acidity of strip and scrub solutions in the process steps for thorium and uranium recovery. The operation diagrams have been constructed using equilibrium experimental data which correspond to conditions observed in laboratory. (Author) [pt

Uranium Elemental and Isotopic Constraints on Groundwater Flow Beneath the Nopal I Uranium Deposit, Pena Blanca, Mexico

Energy Technology Data Exchange (ETDEWEB)

S.J. Goldstein; M.T. Murrell; A.M. Simmons

2005-07-11

The Nopal I uranium deposit in Chihuahua, Mexico, is an excellent analogue for evaluating the fate of spent fuel, associated actinides, and fission products over long time scales for the proposed Yucca Mountain high-level nuclear waste repository. In 2003, three groundwater wells were drilled directly adjacent to (PB-1) and 50 m on either side of the uranium deposit (PB-2 and PB-3) in order to evaluate uranium-series transport in three dimensions. After drilling, uranium concentrations were elevated in all of the three wells (0.1-18 ppm) due to drilling activities and subsequently decreased to {approx}5-20% of initial values over the next several months. The {sup 234}U/{sup 238}U activity ratios were similar for PB-1 and PB-2 (1.005 to 1.079) but distinct for PB-3 (1.36 to 1.83) over this time period, suggesting limited mixing between groundwater from these wells over these short time and length scales. Regional groundwater wells located up to several km from the deposit also have distinct uranium isotopic characteristics and constrain mixing over larger length and time scales. We model the decreasing uranium concentrations in the newly drilled wells with a simple one-dimensional advection-dispersion model, assuming uranium is introduced as a slug to each of the wells and transported as a conservative tracer. Using this model for our data, the relative uranium concentrations are dependent on both the longitudinal dispersion as well as the mean groundwater flow velocity. These parameters have been found to be correlated in both laboratory and field studies of groundwater velocity and dispersion (Klotz et al., 1980). Using typical relationships between velocity and dispersion for field and laboratory studies along with the relationship observed from our uranium data, both velocity (1-10 n/yr) and dispersion coefficient (1E-5 to 1E-2 cm{sup 2}/s) can be derived from the modeling. As discussed above, these relatively small flow velocities and dispersivities agree with

Discussion on the genesis of Zhongchuan uranium deposit

International Nuclear Information System (INIS)

Zhang Yulong; Zhang Chengzhong

2008-01-01

Through elaborating the geological setting, deposit and orebody geological charactors and hydrological features, the ore controlling factors are analysed and the genesis of Zhongchuan uranium deposit is discussed in the way of deposit occurrence, mineral asembleage and matalization ages. It is believed that uranium deposit was formed under the regional uplifting background with the exogenous mechanism and its genesis belongs to surface leaching. (authors)

Supply of enriched uranium for research reactors

Energy Technology Data Exchange (ETDEWEB)

Mueller, H. [NUKEM GmbH, Alzenau (Germany)

1997-08-01

Since the RERTR-meeting In Newport/USA in 1990 the author delivered a series of papers in connection with the fuel cycle for research reactors dealing with its front-end. In these papers the author underlined the need for unified specifications for enriched uranium metal suitable for the production of fuel elements and made proposals with regard to the re-use of in Europe reprocessed highly enriched uranium. With regard to the fuel cycle of research reactors the research reactor community was since 1989 more concentrating on the problems of its back-end since the USA stopped the acceptance of spent research reactor fuel on December 31, 1988. Now, since it is apparent that these back-end problem have been solved by AEA`s ability to reprocess and the preparedness of the USA to again accept physically spent research reactor fuel the author is focusing with this paper again on the front-end of the fuel cycle on the question whether there is at all a safe supply of low and high enriched uranium for research reactors in the future.

Supply of enriched uranium for research reactors

International Nuclear Information System (INIS)

Mueller, H.

1997-01-01

Since the RERTR-meeting In Newport/USA in 1990 the author delivered a series of papers in connection with the fuel cycle for research reactors dealing with its front-end. In these papers the author underlined the need for unified specifications for enriched uranium metal suitable for the production of fuel elements and made proposals with regard to the re-use of in Europe reprocessed highly enriched uranium. With regard to the fuel cycle of research reactors the research reactor community was since 1989 more concentrating on the problems of its back-end since the USA stopped the acceptance of spent research reactor fuel on December 31, 1988. Now, since it is apparent that these back-end problem have been solved by AEA's ability to reprocess and the preparedness of the USA to again accept physically spent research reactor fuel the author is focusing with this paper again on the front-end of the fuel cycle on the question whether there is at all a safe supply of low and high enriched uranium for research reactors in the future

Contribution to the study of nuclear fuel materials with a metallic uranium base

International Nuclear Information System (INIS)

Englander, M.

1957-11-01

In a power reactor destined to supply industrially recoverable thermal energy, the most economical source of heat still consists of natural metallic uranium. However, the nuclear fuel material, most often employed in the form of rods of 20 to 40 mm diameter, is subjected to a series of stresses which lead to irreversible distortions usually incompatible with the substructure of the reactor. As a result the fuel material must possess at the outset a certain number of qualities which must be determined. Investigations have therefore been carried out, first on the technological characters peculiar to each of the three allotropic phases of pure uranium metal, and on their interactions on the stabilisation of the material which consists of either cast uranium or uranium pile-treated in the γ phase. (author) [fr

Determination of uranium in industrial and environmental samples. Vol. 4

Energy Technology Data Exchange (ETDEWEB)

El-Sweify, F H; Shehata, M K; Metwally, E M; El-Shazly, E A.A.; El-Naggar, H A [Nuclear Chemistry Department, Hot Laborities Center, Atomic Energy Authority, Cairo (Egypt)

1996-03-01

The phosphate ores used at `Abu zaabal fertilizer and chemical company` for the production of some chemicals and fertilizers contain detectable amounts of uranium. In this study, the content of uranium in samples of different products of fertilizers, gypsum, and phosphate ore were determined using NAA, and gamma ray spectroscopy of the irradiated samples. Another method based on measuring the natural radioactivity of {sup 238} U series for non-irradiated samples using gamma-ray spectroscopy was also used for determine uranium content in the samples. In the NAA method, the content of U(ppm) in the samples was been computed from the photopeak activity of the lines = 106.1, 228.2, and 277.5 KeV of {sup 239} Np induced in the irradiated samples, and the uranium standard simultaneously irradiated. the gamma-ray spectra, and the decay curves are given. In the second method the gamma-ray spectra of the natural radioactivity of the samples and uranium standard were measured. The gamma-transition of energies 295.1, 251.9 KeV for {sup 214} Pb; 609.3, 768.4, 1120.3, 1238.1 KeV for {sup 214} Bi were determined. The uranium {sup 23U} traces in drainage water was also determined spectrophotometrically using arsenazo-III after preconcentration of uranium from the pretreated drainage water in column packed with chelex-100 resin. The recovery was found to be 90 {+-} 5%. 11 figs., 3 tabs.

In situ leaching of uranium: Technical, environmental and economic aspects

International Nuclear Information System (INIS)

1989-01-01

Within the framework of its activities in nuclear raw materials the International Atomic Energy Agency has convened a series of meetings to discuss various aspects of uranium ore processing technology, recovery of uranium from non-conventional resources and development of projects for the production of uranium concentrates including economic aspects. As part of this continuing effort to discuss and document important aspects of uranium production the IAEA convened a Technical Committee Meeting on Technical, Economic and Environmental Aspects of In-Situ Leaching. Although the use of this technique is limited by geological and economic constraints, it has a significant potential to produce uranium at competitive prices. This is especially important in the current uranium market which is mainly characterised by large inventories, excess production capability and low prices. This situation is not expected to last indefinitely but it is unlikely to change drastically in the next ten years or so. This Technical Committee Meeting was held in Vienna from 3 to 6 November 1987 with the attendance of 24 participants from 12 countries. Eight papers were presented. Technical sessions covered in-situ mining research, environmental and licensing aspects and restoration of leached orebodies; the technological status of in-situ leaching, the current status and future prospects of in-situ leaching of uranium in Member States, general aspects of planning and implementation of in-situ projects and the economics of in-situ leaching. Refs, figs and tabs

Pengaruh Kandungan Uranium Dalam Umpan Terhadap Efisiensi Pengendapan Uranium

OpenAIRE

Torowati

2010-01-01

PENGARUH KANDUNGAN URANIUM DALAM UMPAN TERHADAP EFISIENSI PENGENDAPAN URANIUM. Setiap aktivitas analisis di Laboratorium Kendali Kualitas, Bidang Bahan Bakar Nuklir selalu dihasilkan limbah radioaktif cair. Limbah radioaktif cair di laboratorium masih mengandung uranium yang cukup besar ± 0,600 g U/l dengan keasamaan yang cukup besar pula. Karena uranium mempunyai nilai ekonomis yang cukup tinggi maka perlu USAha untuk mengambil kembali uranium tersebut. Pada kegiatan ini telah dilak...

Summary of Adsorption Capacity and Adsorption Kinetics of Uranium and Other Elements on Amidoxime-based Adsorbents from Time Series Marine Testing at the Pacific Northwest National Laboratory

International Nuclear Information System (INIS)

Gill, Gary A.; Das, Sadananda; Mayes, Richard; Saito, Tomonori; Brown, Suree S.; Tsouris, Constantinos; Tsouris, Costas; Wai, Chien M.; Pan, Horng-Bin

2016-01-01

The Pacific Northwest National Laboratory (PNNL) has been conducting marine testing of uranium adsorbent materials for the Fuel Resources Program, Department of Energy, Office of Nuclear Energy (DOE-NE) beginning in FY 2012. The marine testing program is being conducted at PNNL's Marine Sciences Laboratory (MSL), located at Sequim Bay, along the coast of Washington. One of the main efforts of the marine testing program is the determination of adsorption capacity and adsorption kinetics for uranium and selected other elements (e.g. vanadium, iron, copper, nickel, and zinc) for adsorbent materials provided primarily by Oak Ridge National Laboratory (ORNL), but also includes other Fuel Resources Program participants. This report summarizes the major marine testing results that have been obtained to date using time series sampling for 42 to 56 days using either flow-through column or recirculating flume exposures. The major results are highlighted in this report, and the full data sets are appended as a series of Excel spreadsheet files. Over the four year period (2012-2016) that marine testing of amidoxime-based polymeric adsorbents was conducted at PNNL's Marine Science Laboratory, there has been a steady progression of improvement in the 56-day adsorbent capacity from 3.30 g U/kg adsorbent for the ORNL 38H adsorbent to the current best performing adsorbent prepared by a collaboration between the University of Tennessee and ORNL to produce the adsorbent SB12-8, which has an adsorption capacity of 6.56 g U/kg adsorbent. This nearly doubling of the adsorption capacity in four years is a significant advancement in amidoxime-based adsorbent technology and a significant achievement for the Uranium from Seawater program. The achievements are evident when compared to the several decades of work conducted by the Japanese scientists beginning in the 1980's (Kim et al., 2013). The best adsorbent capacity reported by the Japanese scientists was 3.2 g U/kg adsorbent for a 180

Summary of Adsorption Capacity and Adsorption Kinetics of Uranium and Other Elements on Amidoxime-based Adsorbents from Time Series Marine Testing at the Pacific Northwest National Laboratory

Energy Technology Data Exchange (ETDEWEB)

Gill, Gary A. [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Sciences Lab.; Kuo, Li-Jung [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Sciences Lab.; Strivens, Jonathan E. [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Sciences Lab.; Wood, Jordana R. [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Sciences Lab.; Schlafer, Nicholas J. [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Sciences Lab.; Janke, Christopher J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Das, Sadananda [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Mayes, Richard [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Saito, Tomonori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Brown, Suree S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Tsouris, Constantinos [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Tsouris, Costas [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wai, Chien M. [Univ. of Idaho, Moscow, ID (United States); LCW Supercritical Technologies, Seattle, WA (United States); Pan, Horng-Bin [Univ. of Idaho, Moscow, ID (United States)

2016-09-29

The Pacific Northwest National Laboratory (PNNL) has been conducting marine testing of uranium adsorbent materials for the Fuel Resources Program, Department of Energy, Office of Nuclear Energy (DOE-NE) beginning in FY 2012. The marine testing program is being conducted at PNNL’s Marine Sciences Laboratory (MSL), located at Sequim Bay, along the coast of Washington. One of the main efforts of the marine testing program is the determination of adsorption capacity and adsorption kinetics for uranium and selected other elements (e.g. vanadium, iron, copper, nickel, and zinc) for adsorbent materials provided primarily by Oak Ridge National Laboratory (ORNL), but also includes other Fuel Resources Program participants. This report summarizes the major marine testing results that have been obtained to date using time series sampling for 42 to 56 days using either flow-through column or recirculating flume exposures. The major results are highlighted in this report, and the full data sets are appended as a series of Excel spreadsheet files. Over the four year period (2012-2016) that marine testing of amidoxime-based polymeric adsorbents was conducted at PNNL’s Marine Science Laboratory, there has been a steady progression of improvement in the 56-day adsorbent capacity from 3.30 g U/kg adsorbent for the ORNL 38H adsorbent to the current best performing adsorbent prepared by a collaboration between the University of Tennessee and ORNL to produce the adsorbent SB12-8, which has an adsorption capacity of 6.56 g U/kg adsorbent. This nearly doubling of the adsorption capacity in four years is a significant advancement in amidoxime-based adsorbent technology and a significant achievement for the Uranium from Seawater program. The achievements are evident when compared to the several decades of work conducted by the Japanese scientists beginning in the 1980’s (Kim et al., 2013). The best adsorbent capacity reported by the Japanese scientists was 3.2 g U/kg adsorbent for a

The Dissolution of Uranium Oxides in HB-Line Phase 1 Dissolvers

International Nuclear Information System (INIS)

Gray, J.H.

2003-01-01

A series of characterization and dissolution studies has been performed to define flowsheet conditions for the dissolution of uranium oxide materials in dissolvers. The samples selected for analysis were uranium oxide materials. The selection of these uranium oxide materials for characterization and dissolution studies was based on high enriched uranium content and trace levels of plutonium. Test results from the characterization study identified ferric oxide (Fe2O3) and iron/chromium/nickel (Fe/Cr/Ni) particles as impurities along with the tri-uranium oxide (U3O8) and uranium trioxide (UO3). The weight percent uranium in this material was found to vary depending on the impurity content. The trace impurity plutonium appears to be associated with the Fe/Cr/Ni particles. A small amount of absorbed moisture and waters of hydration is present. Most of the uranium oxides easily dissolved in low-molar nitric acid solutions without fluoride within one to two hours at solution temperature s between 60-80 degrees C. A small amount of residue remained following this dissolution step. To assure complete dissolution of uranium from these oxide materials, an additional dissolution step at 90 degrees C to boiling for at least one to two hours has been suggested. Only trace amounts of iron associated with Fe2O3 and Fe/Cr/Ni particles will dissolve during the dissolution steps. Neither hydrogen nor heat will be generated during the dissolution of these uranium oxide materials in nitric acid solutions. Some brown nitrogen dioxide (NO2) fumes will be generated during the dissolution of U3O8

Mineralogical and paragenetical problems of the Mecsek uranium ore

International Nuclear Information System (INIS)

Vincze, J.; Fazekas, V.

1979-01-01

The latest results of the ore-mineralogical examination of the uranium ore of a deposit included in Permian sandstones in the Mecsek Mountains, southern Hungary, are presented. The phases of the minerals belonging to the uranium oxide series and their types of development, the post-coffinite nasturan pseudomorphs and the relationship between nasturan and coffinite are dealt with. Of the sulphide ore minerals associated with uranium ore mineralization the type determinant mineral is pyrite, i.e. the mineral forming their bulk and partly represented by characteristically finely aggregated ''bacteriopyrite'' and/or spherical pyrite and ''framboidal pyrite. The textural pattern of the ore mineralization is of typically matrix type. The matrix of sandstone is constituted by carbonate minerals, ''hydromicas'' and ore minerals. The matrix and, consequently, the ore minerals will corrode and consume the allothigenic detrital rockforming minerals, the feldspar, quartz-porphyry and quartz. (A.L.)

Glances on uranium. From uranium in the earth to electric power

International Nuclear Information System (INIS)

Valsardieu, C.

1995-01-01

This book is a technical, scientific and historical analysis of the nuclear fuel cycle from the origin of uranium in the earth and the exploitation of uranium ores to the ultimate storage of radioactive wastes. It comprises 6 chapters dealing with: 1) the different steps of uranium history (discovery, history of uranium chemistry, the radium era, the physicists and the structure of matter, the military uses, the nuclear power, the uranium industry and economics), 2) the uranium in nature (nuclear structure, physical-chemical properties, radioactivity, ores, resources, cycle, deposits), 3) the sidelights on uranium history (mining, prospecting, experience, ore processing, resources, reserves, costs), 4) the uranium in the fuel cycle, energy source and industrial product (fuel cycle, fission, refining, enrichment, fuel processing and reprocessing, nuclear reactors, wastes management), 5) the other energies in competition and the uranium market (other uranium uses, fossil fuels and renewable energies, uranium market), and 6) the future of uranium (forecasting, ecology, economics). (J.S.)

Determination of uranium in organic phase by flow injection spectrophotometric analysis

International Nuclear Information System (INIS)

Yu Yiyun

1998-01-01

Based on the use of merging zone circuit and simulating a series of standard solution of uranium in organic phase, uranium in unknown organic phase sample was determined by flow injection spectrophotometry. A linear calibration graph was obtained with correlation coefficient of 0.999 for uranium concentration in organic phase over 10∼200 mg/L. Isopropyl alcohol was used as carrier solution. Mixing colour solution contains isopropyl alcohol, triethanolamine, masking reagent and Br-PADAP. The relative standard deviation of the method was better than +-5%. Determination of each sample can be completed in one minute. The method characteristic is: (1) using merging zone and simulating standard solution of uranium in organic phase, the method is sensitive and reliable; (2) even if the determined solution was in turbid condition, it can be quantitatively determined; (3) by means of solution replace technique, the tube of peristaltic pump can be used over a long period of time

Safety Parameters for the Recycled Uranium Loaded into a CANDU Reactor

International Nuclear Information System (INIS)

Park, Chang Je; Kang, Kweon Ho; Na, Sang Ho; Kim, Young Hee; Ryu, Ho Jin; Park, Geun Il; Song, Kee Chan

2008-01-01

In order to recover uranium and TRU from spent nuclear fuels, a pyroprocessing has been developed through a dry and metallurgical reprocess technology using a series of electrolyses such as an electro-reduction, an electro-refining, and an electro-winning. When the spent fuel is being fed into the pyroprocess, most of the uranium is gathered in metallic form around a solid cathode during an electro-refining process. It is expected that the recovered uranium will be sent to a spent fuel storage site after converting it into a metal ingot form to reduce its storage space and transportation burden. However, the weight percent of U-235 in the recovered uranium is about 0.9 wt% and it is sufficiently re-utilized in a heavy water reactor which uses a natural uranium fuel. The reuse of recovered uranium will bring not only a huge economical profit and save of uranium resources but also an alleviation of burden on the management and disposal of the spent fuel. A previous research on recycling of recovered uranium was carried out and most of the recovered uranium was assumed to be imported from abroad at that time. The preliminary results showed there is a sufficient possibility to recycle recovered uranium in terms of a reactor's characteristics as well as the fuel performance. And the DUPIC (direct use of spent pressurized water reactor fuel into CANDU reactor) program has also been performed and demonstrated the fundamental technologies. The recovered uranium from a pyroprocess contains some TRU as an impurity and it will exhibit a slightly different behavior from the previous recycling options. In this paper, the reactor's characteristics including safety parameters are investigated based on the lattice calculations which are performed for the CANFELX bundle

Health concerns in uranium mining and milling

International Nuclear Information System (INIS)

Archer, V.E.

1981-01-01

Mortality of uranium miners form both lung cancer and other respiratory diseases is strongly dependent on exposure to radon daughters, cigarette smoking and height. Lung cancer among 15 different mining groups (uranium, iron, led, zinc) was analyzed to determine what factors influence incidence and the induction-latent period. At low exposure or exposure rates, alpha radiation is more efficient in inducing lung cancer, producing an upward convex exposure-response curve. The induction-latent period is shortened by increased age at start of mining, by cigarette smoking and by high exposure rates. For a follow-up period of 20 to 25 years, the incidence increases with age at start of mining, with magnitude of exposure and with amount of cigarette smoking. Instead of extrapolating downward from high exposures to estimate risk at low levels, it is suggested that it might be more appropriate to use cancer rates associated with background radiation as the lowest point on the exposure-response curve. Although health risks are much greater in uranium mines than mills, there is some health risk in the mills from long-lived radioactive materials

Hydrologic and environmental controls on uranium-series and strontium isotope ratios in a natural weathering environment

Science.gov (United States)

White, A. M.; Ma, L.; Moravec, B. G.; McIntosh, J. C.; Chorover, J.

2017-12-01

In a remote, volcanic headwater catchment of the Jemez River Basin Critical Zone Observatory (JRB-CZO) in NM, stable water isotopes and solute chemistry have shown that snowmelt infiltrates and is stored before later discharging into springs and streams via subsurface flowpaths that vary seasonally. Therefore, water-rock reactions are also expected to change with season as hydrologic flowpaths transport water, gases and solutes through different biogeochemical conditions, rock types and fracture networks. Uranium-series isotopes have been shown to be a novel tracer of water-rock reactions and source water contributions while strontium isotopes are frequently used as indicators of chemical weathering and bedrock geology. This study combines both isotopes to understand how U and Sr isotope signatures evolve through the Critical Zone (CZ). More specifically, this work examines the relationship between seasonality, water transit time (WTT), and U-series and Sr isotopes in stream and spring waters from three catchments within the JRB-CZO, as well as lithology, rock type and CZ structure in solid phase cores. Samples from ten springs with known WTTs were analyzed for U and Sr isotopes to determine the effect of WTT on the isotopic composition of natural waters. Results suggest that WTT alone cannot explain the variability of U and Sr isotopes in JRB-CZO springs. Stream samples were also collected across two water years to establish how seasonality controls surface water isotopic composition. U and Sr isotope values vary with season, consistent with a previous study from the La Jara catchment; however, this study revealed that these changes do not show a systematic pattern among the three catchments suggesting that differences in the mineralogy and structure of the deep CZ in individual catchments, and partitioning of water along deep vs surficial and fracture vs matrix flow paths, likely also control isotopic variability. The distribution of U-series and Sr isotopes in

Analysis of trace uranium in human urine by using the fission track method

International Nuclear Information System (INIS)

Chen Huailu; Yang Huazhang; Zhao Dongzhi; Wang Kaixue

1988-01-01

In order to know the contents of uranium in human urine, urine samples from 10 healthy persons with different ages and sexes in Lanzhou area were analysed with the fisson track method. The results, in contrast with the contents of uranium in Yellow River water (in Lanzhou section), tap-water and rainwater, indicated that the content of uranium in human urine was lower than that in tap-water. From the ratio of uranium in human urine to that in tap-water, the maximum excreted rate of uranium from urine is evaluated to be 42.2%

Uranium prospecting; La prospection de l'uranium

Energy Technology Data Exchange (ETDEWEB)

Roubault, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1955-07-01

This report is an instruction book for uranium prospecting. It appeals to private prospecting. As prospecting is now a scientific and technical research, it cannot be done without preliminary studies. First of all, general prospecting methods are given with a recall of fundamental geologic data and some general principles which are common with all type of prospecting. The peculiarities of uranium prospecting are also presented and in particular the radioactivity property of uranium as well as the special aspect of uranium ores and the aspect of neighbouring ores. In a third part, a description of the different uranium ores is given and separated in two different categories: primary and secondary ores, according to the place of transformation, deep or near the crust surface respectively. In the first category, the primary ores include pitchblende, thorianite and rare uranium oxides as euxenite and fergusonite for example. In the second category, the secondary ores contain autunite and chalcolite for example. An exhaustive presentation of the geiger-Mueller counter is given with the presentation of its different components, its functioning and utilization and its maintenance. The radioactivity interpretation method is showed as well as the elaboration of a topographic map of the measured radioactivity. A brief presentation of other detection methods than geiger-Mueller counters is given: the measurement of fluorescence and a chemical test using the fluorescence properties of uranium salts. Finally, the main characteristics of uranium deposits are discussed. (M.P.)

X-ray diffraction study of reversible deformation mechanisms in the aged uranium-6.5 niobium alloy

International Nuclear Information System (INIS)

Carpenter, D.A.

1985-01-01

The x-ray diffraction (XRD) data from 200 0 C/2h-aged uranium-6.5 wt % niobium (U-6.5Nb) alloys, taken under stress as a function of strain, revealed a gamma-zero (γ 0 )→ alpha prime-prime (α'') thermoelastic martensitic phase transformation. It was concluded that the primary reversible deformation modes consisted of the movement of γ 0 /α'' interphase interfaces and α'' intervariant interfaces. Specimen elasticity at low strains was associated with the retreat of interphase interfaces. At higher strains, interphase interfaces did not recover significantly on unloading, and elasticity was due primarily to the retreat of α'' intervariant interfaces

Geological exploration of uranium ores at Burgos' basin

International Nuclear Information System (INIS)

Cabrera Valdez, M.E.

1975-01-01

The outcrop sediments of the Burgos river basin cover the complete Cenozoic sequence from the Pallaeocene to recent date, and are arranged in the form of parallel strips with a regional dip towards the east, in which direction the sediments become steadily younger. Generally speaking they correspond to a regressive process the lithology of which is an alternation of shales, sandstones, tuffaceous material and conglomerates. The explorations and evaluations of sedimentary uranium deposits so far carried out in the north-east of Mexico show close relationships between the mineralization and the sedimentary processes of the enclosing rock. Analysis of the sedimentary-type uranium ore bodies in Mexico indicates characteristics very similar to those found in the deposits of the same type which were first studied and described in southern Texas and were used as a standard for the first exploratory studies. The uranium ore in the State of Texas is found in sands belonging mainly to the Jackson group of the Eocene and, to a lesser extent, the Catahoula formation of Miocene-Oligocene age. In the Burgos basin the existence of uranium deposits in the non-marine Frio formation of Oligocene age, with geological characteristics similar to the Texan deposits, has been demonstrated. This comparative analysis suggests very good prospects for uranium exploration in the region; it is recommended that priority be given to intensive study of the sediments of the non-marine member of the Frio formation, and the Jackson and Catahoula formations. (author)

Political economy of African uranium and its role in international markets. Final report. International energy studies program

International Nuclear Information System (INIS)

Lynch, M.C.; Neff, T.L.

1982-03-01

The history of uranium development in Africa is briefly summarized. Today there are 4 major uranium producing countries in Africa: Gabon, Niger, Namibia, and South Africa. These nations have the possibility of political instability. In addition, the uranium market has undergone a series of radical changes over the past decade. How these African nations have responded to this changing market, and how their roles in the international market relate to domestic political and economic factors are the topics of this report

A time-series phytoremediation experiment with sunflowers (Helianthus annuus on a former uranium mining site

Directory of Open Access Journals (Sweden)

Kötschau A.

2013-04-01

Full Text Available On a test field situated at a former uranium mining site near Ronneburg (Thuringia, Germany a small scale time-series field experiment with sunflowers (Helianthus annuus was carried out. This area ghas elevated contents for the heavy metals Cd, Co, Cr, Cu, Ni, Zn including the radionuclides U and Th. Over a time period of 24 weeks the sunflowers were cultivated on homogenized soil substrate and regularly harvested. The aim was to find the ideal moment to harvest the sunflowers, being defined as having the best balance between the extraction of the contaminants and a high biomass produced. The contents of the elements were determined in soil, roots and above-ground plant parts. The contents in the above-ground plant showed no clear increasing or decreasing trend over time, so they were not the appropriate values to determine the best moment to harvest. Instead the total extracted masses (content in μg/g x biomass in g of the contaminants in the above-ground plant parts were calculated. According to this the best moment to harvest the sunflower plants was reached after 24 weeks of vegetation, because the highest extracted masses for all contaminants were calculated to this time. Additionally the biomass, which could be used e.g. for bio-fuel production, was highest at this time.

Uranium

International Nuclear Information System (INIS)

Stewart, E.D.J.

1974-01-01

A discussion is given of uranium as an energy source in The Australian economy. Figures and predictions are presented on the world supply-demand position and also figures are given on the added value that can be achieved by the processing of uranium. Conclusions are drawn about Australia's future policy with regard to uranium (R.L.)

Uranium, depleted uranium, biological effects

International Nuclear Information System (INIS)

2001-01-01

Physicists, chemists and biologists at the CEA are developing scientific programs on the properties and uses of ionizing radiation. Since the CEA was created in 1945, a great deal of research has been carried out on the properties of natural, enriched and depleted uranium in cooperation with university laboratories and CNRS. There is a great deal of available data about uranium; thousands of analyses have been published in international reviews over more than 40 years. This presentation on uranium is a very brief summary of all these studies. (author)

The depositional and hydrogeologic environment of tertiary uranium deposits, South Texas uranium province

International Nuclear Information System (INIS)

Galloway, W.E.

1985-01-01

Uranium ore bodies of the South Texas Uranium Province occur within the most transmissive sand facies of coastal-plain fluvial and shore-zone depositional systems. Host strata range in age from Eocene through Miocene. Ore bodies formed at the fringes of epigenetic oxidation tongues near intrinsic organic debris or iron-disulfide mineral reductants. Mineralized Eocene units, which include the Carrizo and Whitsett Sandstones, subcropped beneath tuffaceous Oligocene through early Miocene coastal plain sediments. Roll-front mineralization occurred because of this direct hydrologic continuity between an aquifer and a uranium source. Most ore occurs within coarse, sand-rich, arid-region, bed-load fluvial systems of the Oligocene through Miocene Catahoula, Oakville, and Goliad Formations. Host sediments were syndepositionally oxidized and leached. Reductant consists predominantly of epigenetic pyrite precipitated from deep, sulfide-rich thermobaric waters introduced into the shallow aquifers along fault zones. Mineralization fronts are commonly entombed within reduced ground. Modern ground waters are locally oxidizing and redistributing some ore but appear incapable of forming new mineralization fronts. (author)

Solubility measurement of uranium in uranium-contaminated soils

International Nuclear Information System (INIS)

Lee, S.Y.; Elless, M.; Hoffman, F.

1993-08-01

A short-term equilibration study involving two uranium-contaminated soils at the Fernald site was conducted as part of the In Situ Remediation Integrated Program. The goal of this study is to predict the behavior of uranium during on-site remediation of these soils. Geochemical modeling was performed on the aqueous species dissolved from these soils following the equilibration study to predict the on-site uranium leaching and transport processes. The soluble levels of total uranium, calcium, magnesium, and carbonate increased continually for the first four weeks. After the first four weeks, these components either reached a steady-state equilibrium or continued linearity throughout the study. Aluminum, potassium, and iron, reached a steady-state concentration within three days. Silica levels approximated the predicted solubility of quartz throughout the study. A much higher level of dissolved uranium was observed in the soil contaminated from spillage of uranium-laden solvents and process effluents than in the soil contaminated from settling of airborne uranium particles ejected from the nearby incinerator. The high levels observed for soluble calcium, magnesium, and bicarbonate are probably the result of magnesium and/or calcium carbonate minerals dissolving in these soils. Geochemical modeling confirms that the uranyl-carbonate complexes are the most stable and dominant in these solutions. The use of carbonate minerals on these soils for erosion control and road construction activities contributes to the leaching of uranium from contaminated soil particles. Dissolved carbonates promote uranium solubility, forming highly mobile anionic species. Mobile uranium species are contaminating the groundwater underlying these soils. The development of a site-specific remediation technology is urgently needed for the FEMP site

Uranium Immobilization in Wetland Soils

Science.gov (United States)

Jaffe, Peter R.; Koster van Groos, Paul G.; Li, Dien; Chang, Hyun-Shik; Seaman, John C.; Kaplan, Daniel I.; Peacock, Aaron D.; Scheckel, Kirk

2014-05-01

In wetlands, which are a major feature at the groundwater-surface water interface, plants deliver oxygen to the subsurface to keep root tissue aerobic. Some of this oxygen leaches into the rhizosphere where it will oxidize iron that typically precipitates on or near roots. Furthermore, plans provide carbon via root exudates and turnover, which in the presence of the iron oxides drives the activity of heterotrophic iron reducers in wetland soils. Oxidized iron is an important electron acceptor for many microbially-driven transformations, which can affect the fate and transport of several pollutants. It has been shown that heterotrophic iron reducing organisms, such as Geobacter sp., can reduce water soluble U(VI) to insoluble U(IV). The goal of this study was to determine if and how iron cycling in the wetland rhizosphere affects uranium dynamics. For this purpose, we operated a series of small-scale wetland mesocosms in a greenhouse to simulate the discharge of uranium-contaminated groundwater to surface waters. The mesocosms were operated with two different Fe(II) loading rates, two plant types, and unplanted controls. The mesocosms contained zones of root exclusion to differentiate between the direct presence and absence of roots in the planted mesocosms. The mesocosms were operated for several month to get fully established, after which a U(VI) solution was fed for 80 days. The mesocosms were then sacrificed and analyzed for solid-associated chemical species, microbiological characterization, micro-X-ray florescence (µ-XRF) mapping of Fe and U on the root surface, and U speciation via X-ray Absorption Near Edge Structure (XANES). Results showed that bacterial numbers including Geobacter sp., Fe(III), as well as total uranium, were highest on roots, followed by sediments near roots, and lowest in zones without much root influence. Results from the µ-XRF mapping on root surfaces indicated a strong spatial correlation between Fe and U. This correlation was

Radium, uranium and metals in acidic or alkaline uranium mill

International Nuclear Information System (INIS)

Somot, St.

1997-01-01

Uranium mill study sites have been chosen in function of their different characteristics: deposits age, treatment nature (alkaline or acid), mill origin. The realization of specific drilling allowed the simultaneous study of the interstitial water and the solid fraction of samples, cut at determined deep. A radiation imbalance between 230 Th and 226 Ra is observed in the acid treatment residues. The trace elements concentration spectrum is directly bound to the nature of the ore. Diamagnetic evolutions are observed in residues. The uranium concentrations are higher in carbonated waters than in calcic sulfated waters. The selective sequential lixiviation showed that the 226 Ra activity of the interstitial water is controlled by the Gypsum in acid treatment residues. In other hand in the alkaline treatment waters, the carbonates occur. The Ra retention is largely bound to the Fe and Mn oxy-hydroxides. (A.L.B.)

Uranium complex recycling method of purifying uranium liquors

International Nuclear Information System (INIS)

Elikan, L.; Lyon, W.L.; Sundar, P.S.

1976-01-01

Uranium is separated from contaminating cations in an aqueous liquor containing uranyl ions. The liquor is mixed with sufficient recycled uranium complex to raise the weight ratio of uranium to said cations preferably to at least about three. The liquor is then extracted with at least enough non-interfering, water-immiscible, organic solvent to theoretically extract about all of the uranium in the liquor. The organic solvent contains a reagent which reacts with the uranyl ions to form a complex soluble in the solvent. If the aqueous liquor is acidic, the organic solvent is then scrubbed with water. The organic solvent is stripped with a solution containing at least enough ammonium carbonate to precipitate the uranium complex. A portion of the uranium complex is recycled and the remainder can be collected and calcined to produce U 3 O 8 or UO 2

Uranium occurence in California near Bucaramanga (Columbia)

International Nuclear Information System (INIS)

Heider Polania, J.

1980-01-01

The mining district of California, Bucaramanga, is on the west side of the Cordillera Oriental in the Santander massif region. The oldest rocks of the area form a complex of metamorphites and migmatites of the predevonic age. Amphibolite various types of paragneiss and orthogneiss are represented. Several stages of metamorphism can be documented in some rocks, as well as double anatexis. Triassic to jurassic quarz diorites and leukogranites show wide distribution. Porphyric rocks of granodioritic to granitic composition, to which the uranium mineralization is mainly bonded, intruded into the sediments of the lower cretaceous. Atomic absorption spectral analyses were carried out for the elements Cu, Zn and Li, as well as the uranium contents of some samples using fluorimetry. Uranium is primarily bonded to pitch blende and coffinite. The latter mostly occur in fine distribution grown in quarz and belong to the most recent mineralization phase. Autunite, meta-autunite, torbernite, meta-torbernite, zeunerite, meta-zeunerite and meta uranocircite detected as secondary uranium minerals. (orig./HP) [de

Occurrences of uranium at Clinton, Hunterdon County, New Jersey

Science.gov (United States)

McKeown, F.A.; Klemic, H.; Choquette, P.W.

1954-01-01

An occurrence of uranium at Clinton, Hunterdon County, N. J. was first brought to the attention of the U.S. Geological Survey when Mr. Thomas L. Eak of Avenel, N. J. submitted to the Survey a sample containing 0.068 percent uranium. Subsequent examinations of the area around Clinton indicated that detailed mapping and study were warranted. The uranium occurrences at Clinton are in or associated with fault zones in the Kittatinny limestone of Cambro-Ordovician age. The limestone generally light gray, thick bedded, and dolomitic; chert is common but not abundant. Regionally and locally, faults are the most significant structural features. The local faults at Clinton are the loci for most of the uranium. The largest fault can be traced for about 700 feet and is radioactive everywhere it crops out. Samples from this fault contain as much as 0.038 percent uranium; the average content is about 0.010 percent uranium. Uranium also occurs disseminated in two 4-inch layers of black feldspathic dolomite and in several zones of residual soil derived from the Kittatinny limestone. The black layers contain as much as 0.046 percent uranium and can be traced only about 20 feet along strike. They are cut by a small fault that is also radioactive. The radioactive soil zones are roughly elongated parallel to bedding. Soil from them contains up to 0.008 percent uranium. The uranium occurrences are best explained by a supergene origin. The sampling, mapping, and radioactivity testing of uranium occurrences at Clinton indicate they are too low grade to be of current economic interest.

Uranium

International Nuclear Information System (INIS)

Toens, P.D.

1981-03-01

The geological setting of uranium resources in the world can be divided in two basic categories of resources and are defined as reasonably assured resources, estimated additional resources and speculative resources. Tables are given to illustrate these definitions. The increasing world production of uranium despite the cutback in the nuclear industry and the uranium requirements of the future concluded these lecture notes

Natural uranium toxicology - evaluation of internal contamination in man; Toxicologie de l'uranium naturel - essai d'evaluation de la contamination interne chez l'homme

Energy Technology Data Exchange (ETDEWEB)

Chalabreysse, J. [Commissariat a l' Energie Atomique, Pierrelatte (France). Centre d' Etudes Nucleaires

1968-07-01

After reminding the physical and chemical properties of natural uranium which might affect its toxicology, a comprehensive investigation upon natural uranium metabolism and toxicity and after applying occupational exposure standards to this particular poison, it has been determined, from accident reports and human experience reported in the related literature, a series of formulae obtained by theoretical mathematical development giving principles for internal contamination monitoring and disclosure by determining uranium in the urine of occupationally exposed individuals. An assay is performed to determine individual internal contamination according to the various contamination cases. The outlined purposes, mainly practical, required some options and extrapolations. The proposed formula allows a preliminary approach and also to determine shortly a contamination extent or to discuss the systematical urinalysis results as compared with individual radio-toxicology monitoring professional standards. (author) [French] Apres le rappel des caracteristiques physiques et des proprietes chimiques de l'uranium naturel pouvant avoir une influence sur sa toxicologie, l'etude detaillee de son metabolisme et de sa toxicite, puis l'application des normes professionnelles d'exposition au cas particulier de ce toxique, il est etabli, a partir des comptes rendus d'accidents et de l'experimentation humaine rapportes dans la litterature, une serie de formules obtenues par developpement mathematique theorique qui posent les principes de la surveillance et de la mise en evidence de la contamination interne par la recherche et le dosage de l'uranium dans les urines d'individus professionnellement exposes. Un essai d'evaluation de la contamination interne individuelle suivant les differents cas de contamination est effectue. Le formulaire propose permet de faire une premiere approximation et d'apprecier rapidement l'importance d

Uranium and thorium nuclides series determined in medicinal plants commonly used in Brazil

Energy Technology Data Exchange (ETDEWEB)

Silva, P.; Francisconi, L.; Damatto, S. [IPEN/CNEN-SP, Sao Paulo (Brazil)

2014-07-01

In recent years the study of medicinal plants has become the focus of ever more extensive research all over the world due to their diversity and potential as source of medicinal products. According to the World Health Organization approximately 80% of world population makes use of medicinal herbs due to their believed therapeutic action. Besides being used as medicine, medicinal plants are also largely used as dietary supplements. The presence of radionuclides in plants constitutes one of the main pathways for their transfer to man. The amount of radioactive nuclides from U and Th series in edible vegetables are relatively well known since they have been the main concern of research conducted worldwide. Medicinal plants, on the other hand, have been neglected in these studies, possibly because the ingestion of radioactive material through their consumption has not been recognized or was considered insignificant. The objective of the present study was to determine the content of natural radionuclides from {sup 238}U and {sup 232}Th series in 25 species of medicinal plants used in Brazil, both as medicine and as dietary supplement. The medicinal plant samples were obtained in specialized pharmacies and drugstores. The raw plant and their extracts, produced as recommended by the National Agency for Sanitary Vigilance, were analyzed by Instrumental Neutron Activation Analyses for the determination of U and Th and by Total Alpha and Beta Counting after Radiochemical Separation for determination of {sup 226}Ra, {sup 228}Ra and {sup 210}Pb. In the raw plants the activity concentrations varied from 0,08 Bq kg{sup -1} to 8,0 Bq kg{sup -1} for thorium, from < LID to 22 Bq kg{sup -1} for uranium, from 1,8 Bq kg{sup -1} to 12 Bq kg{sup -1} for {sup 226}Ra, from 33 Bq kg{sup -1} to 74 Bq kg{sup -1} for {sup 228}Ra and from 10 Bq kg{sup -1} to 120 Bq kg{sup -1} for {sup 210}Pb. In the extracts, the activity concentrations varied from 9 mBq kg{sup -1} to 137 mBq kg{sup -1} for Th

Recovery of uranium from uranium bearing black shale

International Nuclear Information System (INIS)

Das, Amrita; Yadav, Manoj; Singh, Ajay K.

2016-01-01

Black shale is the unconventional resource of uranium. Recovery of uranium from black shale has been carried out by the following steps: i) size reduction, ii) leaching of uranium in the aqueous medium, iii) fluoride ion removal, iv) solvent extraction of uranium from the aqueous leach solution, v) scrubbing of the loaded solvent after extraction to remove impurities as much as possible and vi) stripping of uranium from the loaded organic into the aqueous phase. Leaching of black shale has been carried out in hydrochloric acid. Free acidity of the leach solution has been determined by potentiometric titration method. Removal of fluoride ions has been done using sodium chloride. Solvent extraction has been carried out by both tributyl phosphate and alamine-336 as extractants. Scrubbing has been tried with oxalic acid and sulphuric acid. Stripping with sodium carbonate solution has been carried out. Overall recovery of uranium is 95%. (author)

Current practices and options for confinement of uranium mill tailings

International Nuclear Information System (INIS)

1981-01-01

At the United Nations Conference on the Human Environment, which took place in Stockholm from 4 to 6 June 1972, national governments were asked to explore, with the International Atomic Energy Agency and other appropriate international organizations, international co-operation on radioactive waste matters including those of mining and tailings disposal. Since that time the IAEA has been active in the field of uranium and thorium mill tailings management. As part of this activity, the present report describes current practices and options for confinement of uranium mill tailings. It is addressed to technical and administrative personnel who are involved in planning and implementing national and industrial programmes on the management of such tailings. In 1974 and 1975 the IAEA convened meetings of experts to review matters of interest and importance in the management of uranium and thorium mine and mill tailings. These activities led to the publication in 1976 of Management of Wastes from the Mining and Milling of Uranium and Thorium Ores, a Code of Practice and Guide to the Code, IAEA Safety Series No. 44. As a continuation of this activity, the IAEA is here dealing more specifically with the design and siting considerations for the management of uranium mill tailings

Uranium resources, 1983

International Nuclear Information System (INIS)

1983-01-01

The specific character of uranium as energy resources, the history of development of uranium resources, the production and reserve of uranium in the world, the prospect regarding the demand and supply of uranium, Japanese activity of exploring uranium resources in foreign countries and the state of development of uranium resources in various countries are reported. The formation of uranium deposits, the classification of uranium deposits and the reserve quantity of each type are described. As the geological environment of uranium deposits, there are six types, that is, quartz medium gravel conglomerate deposit, the deposit related to the unconformity in Proterozoic era, the dissemination type magma deposit, pegmatite deposit and contact deposit in igneaus rocks and metamorphic rocks, vein deposit, sandstone type deposit and the other types of deposit. The main features of respective types are explained. The most important uranium resources in Japan are those in the Tertiary formations, and most of the found reserve belongs to this type. The geological features, the state of yield and the scale of the deposits in Ningyotoge, Tono and Kanmon Mesozoic formation are reported. Uranium minerals, the promising districts in the world, and the matters related to the exploration and mining of uranium are described. (Kako, I.)

IN-SITU RADIONUCLIDE TRANSPORT NEAR THE NOPAL I URANIUM DEPOSIT AT PENA BLANCA, MEXICO: CONSTRAINTS FROM SHORT-LIVED DECAY-SERIES RADIONUCLIDES

Energy Technology Data Exchange (ETDEWEB)

S. Luo; T.L. Ku; V. Todd; M. Murrell; J. Alfredo Rodriguez Pineda; J. Dinsmoor; A. Mitchell

2005-07-11

For nuclear waste management, an important mechanism by which radioactive waste components are isolated from returning to the human environment, the biosphere, is by the geological barrier in which the effectiveness of the barrier is characterized by in-situ retardation factor, i.e., the transport rate of a radionuclide relative to that of groundwater. As part of natural analog studies of the Yucca Mountain Project of the U. S. Department of Energy, we propose such characterization by using naturally-occurring decay-series radioisotopes as an analog. We collected large-volume (>1000 liters) groundwater samples from three wells (PB, Pozos, and PB4, respectively) near the Nopal I Uranium Ore site at Pena Blanca, Mexico, by using an in-situ Mn-cartridge filtration technique for analysis of short-lived decay-series radionuclides. Results show that the activities of short-lived radioisotopes ({sup 228}Ra, {sup 224}Ra and {sup 223}Ra) and activity ratios of {sup 224}Ra/{sup 228}Ra and {sup 224}Ra/{sup 223}Ra are higher at PB and Pozos than at PB4. In contrast, the {sup 210}Po activity is much lower at PB and Pozos than at PB4. The high Ra activities and activities ratios at PB and Pozos are attributable to the high alpha-recoil input from the aquifer rocks, while the high {sup 210}Po activity at PB4 is due to the enhanced colloidal transport. Based on a uranium-series transport model, we estimate that the in-situ retardation factor of Ra is (0.43 {+-} 0.02) x 10{sup 3} at PB, (1.68 {+-} 0.08) x 10{sup 3} at Pozos, and (1.19 {+-} 0.08) x 10{sup 3} at PB4 and that the mean fracture width in the aquifer rocks is about 0.23 {micro}m at PB, 0.37 {micro}m at Posos, and 4.0 {micro}m at PB4, respectively. The large fracture width at PB4 as derived from the model provides an additional evidence to the inference from the Po measurements that particle-reactive radionuclides are transported mainly as colloidal forms through the large fractures in rocks. Our model also suggests that

Uranium management activities

International Nuclear Information System (INIS)

Jackson, D.; Marshall, E.; Sideris, T.; Vasa-Sideris, S.

2001-01-01

One of the missions of the Department of Energy's (DOE) Oak Ridge Office (ORO) has been the management of the Department's uranium materials. This mission has been accomplished through successful integration of ORO's uranium activities with the rest of the DOE complex. Beginning in the 1980's, several of the facilities in that complex have been shut down and are in the decommissioning process. With the end of the Cold War, the shutdown of many other facilities is planned. As a result, inventories of uranium need to be removed from the Department facilities. These inventories include highly enriched uranium (HEU), low enriched uranium (LEU), normal uranium (NU), and depleted uranium (DU). The uranium materials exist in different chemical forms, including metals, oxides, solutions, and gases. Much of the uranium in these inventories is not needed to support national priorities and programs. (author)

Nephrotoxicity of uranium in drinking water from private drilled wells

International Nuclear Information System (INIS)

Selden, Anders I.; Lundholm, Cecilia; Edlund, Bror; Hoegdahl, Camilla; Ek, Britt-Marie; Bergstroem, Bernt E.; Ohlson, Carl-Goeran

2009-01-01

Objectives: To investigate the association between uranium in drinking water from drilled wells and aspects of kidney function measured by sensitive urine tests. Methods: Three hundred and one of 398 eligible subjects (75.6%) aged 18-74 years with daily drinking water supplies from private drilled wells located in uranium-rich bedrock (exposed group) volunteered to participate along with 153 of 271 local controls (56.4%) who used municipal water. Participants responded to a questionnaire on their water consumption and general health, and provided a morning urine sample and drinking water for analysis. Results: The uranium content of well water samples (n=153) varied considerably (range 100 μg/l), while uranium levels in all samples of municipal water (n=14) were below the limit of quantification (0.2 μg/l). Urinary levels of uranium were more than eight times higher in exposed subjects than in controls (geometric means 38 and 4.3 ng/l, respectively; p 2 =0.66). Levels of albumin, β 2 -microglobulin, protein HC as well as kappa and lambda immunoglobulin chains in urine from exposed and controls were similar. The N-acetyl-β-D-glucosaminidase (NAG) activity was significantly lower in the exposed group vs. controls, possibly secondary to differential storage duration of samples from the two groups. Even in regression models adjusting for gender, age and smoking no association of uranium in water and the kidney function parameters was observed. Using uranium in urine in the entire study group as a marker of exposure, however, a tendency of exposure-related increases of β 2 -microglobulin, protein HC and kappa chains were noted. This tendency was enhanced after exclusion of subjects with diabetes mellitus from the analysis. Conclusions: Uranium levels in urine were strongly correlated to levels in drinking water from drilled wells. There were no clear signs of nephrotoxicity from uranium in drinking water at levels recorded in this study, but some indications of an

Estimated dose to man from uranium milling via the terrestrial food-chain pathway

Energy Technology Data Exchange (ETDEWEB)

Rayno, D.R.

1982-01-01

One of the major pathways of radiological exposure to man from uranium milling operations is through the terrestrial food chain. Studies by various investigators have shown the extent of uptake and distribution of U-238, U-234, Th-230, Ra-226, Pb-210, and Po-210 in plants and animals. These long-lived natural radioisotopes, all nuclides of the uranium decay series, are found in concentrated amounts in uranium mill tailings. Data from these investigations are used to estimate the dose to man from consumption of beef and milk contaminated by the tailings. This dose estimate from this technologically enhanced source is compared with that from average normal dietary intake of these radionuclides from natural sources.

Estimated dose to man from uranium milling via the terrestrial food-chain pathway

International Nuclear Information System (INIS)

Rayno, D.R.

1982-01-01

One of the major pathways of radiological exposure to man from uranium milling operations is through the terrestrial food chain. Studies by various investigators have shown the extent of uptake and distribution of U-238, U-234, Th-230, Ra-226, Pb-210, and Po-210 in plants and animals. These long-lived natural radioisotopes, all nuclides of the uranium decay series, are found in concentrated amounts in uranium mill tailings. Data from these investigations are used to estimate the dose to man from consumption of beef and milk contaminated by the tailings. This dose estimate from this technologically enhanced source is compared with that from average normal dietary intake of these radionuclides from natural sources

Isotopic analysis of uranium by thermoionic mass spectrometry

International Nuclear Information System (INIS)

Moraes, N.M.P. de.

1979-01-01

Uranium isotopic ratio measurements by thermoionic spectrometry are presented. Emphasis is given upon the investigation of the parameters that directly affect the precision and accuracy of the results. Optimized procedures, namely, chemical processing, sample loading on the filaments, vaporization, ionization and measurements of ionic currents, are established. Adequate statistical analysis of the data for the calculation of the internal and external variances and mean standard deviation are presented. These procedures are applied to natural and NBS isotopic standard uranium samples. The results obtained agree with the certified values within specified limits. 235 U/ 238 U isotopic ratios values determined for NBS-U500, and a series of standard samples with variable isotopic compositon, are used to calculate mass discrimination factor [pt

Uraniferous opal, Virgin Valley, Nevada: conditions of formation and implications for uranium exploration

Science.gov (United States)

Zielinski, R.A.

1982-01-01

Uraniferous, fluorescent opal, which occurs in tuffaceous sedimentary rocks at Virgin Valley, Nevada, records the temperature and composition of uranium-rich solutions as well as the time of uranium-silica coprecipitation. Results are integrated with previous geologic and geochronologic data for the area to produce a model for uranium mobility that may be used to explore for uranium deposits in similar geologic settings. Uraniferous opal occurs as replacements of diatomite, or silicic air-fall ash layers in tuffaceous lakebeds of the Virgin Valley Formation (Miocene) of Merriam (1907). Fission-track radiography shows uranium to be homogeneously dispersed throughout the opal structure, suggesting coprecipitation of dissolved uranium and silica gel. Fluid inclusions preserved within opal replacements of diatomite have homogenization temperatures in the epithermal range and are of low salinity. Four samples of opal from one locality all have U-Pb apparent ages which suggest uraniferous opal precipitation in late Pliocene time. These ages correspond to a period of local, normal faulting, and highangle faults may have served as vertical conduits for transport of deep, thermalized ground water to shallower levels. Lateral migration of rising solutions occurred at intersections of faults with permeable strata. Silica and some uranium were dissolved from silica-rich host strata of 5-20 ppm original uranium content and reprecipitated as the solutions cooled. The model predicts that in similar geologic settings, ore-grade concentrations of uranium will occur in permeable strata that intersect high-angle faults and that contain uranium source rocks as well as efficient reductant traps for uranium. In the absence of sufficient quantities of reductant materials, uranium will be flushed from the system or will accumulate in low-grade disseminated hosts such as uraniferous opal. ?? 1982.

Provision by the uranium and uranium products

International Nuclear Information System (INIS)

Elagin, Yu.P.

2005-01-01

International uranium market is converted from the buyer market into the seller market. The prices of uranium are high and the market attempts to adapt to changing circumstances. The industry of uranium enrichment satisfies the increasing demands but should to increase ots capacities. On the whole the situation is not stable and every year may change the existing position [ru

Uranium industry framework

International Nuclear Information System (INIS)

Riley, K.

2008-01-01

The global uranium market is undergoing a major expansion due to an increase in global demand for uranium, the highest uranium prices in the last 20 years and recognition of the potential greenhouse benefits of nuclear power. Australia holds approximately 27% of the world's uranium resources (recoverable at under US$80/kg U), so is well placed to benefit from the expansion in the global uranium market. Increasing exploration activity due to these factors is resulting in the discovery and delineation of further high grade uranium deposits and extending Australia's strategic position as a reliable and safe supplier of low cost uranium.

High-temperature thermal conductivity of uranium chromite and uranium niobate

International Nuclear Information System (INIS)

Fedoseev, D.V.; Varshavskaya, I.G.; Lavrent'ev, A.V.; Oziraner, S.N.; Kuznetsova, D.G.

1979-01-01

The technique of determining thermal conductivity coefficient of uranium niobate and uranium chromite on heating with laser radiation is described. Determined is the coefficient of free-convective heat transfer (with provision for a conduction component) by means of a standard specimen. The thermal conductivity coefficients of uranium chromite and niobate were measured in the 1300-1700 K temperature range. The results are presented in a diagram form. It has been calculated, that the thermal conductivity coefficient for uranium niobate specimens is greater in comparison with uranium chromite specimens. The thermal conductivity coefficients of the materials mentioned depend on temperature very slightly. Thermal conductivity of the materials considerably depends on their porosity. The specimens under investigation were fabricated by the pressing method and had the following porosity: uranium chromite - 30 %, uranium niobate - 10 %. Calculation results show, that thermal conductivity of dense uranium chromite is higher than thermal conductivity of dense uranium niobate. The experimental error equals approximately 20 %, that is mainly due to the error of measuring the temperature equal to +-25 deg, with a micropyrometer

Study of reactions between uranium-plutonium mixed oxide and uranium nitride and between uranium oxide and uranium nitride; Etude des reactions entre l`oxyde mixte d`uranium-plutonium et le nitrure d`uranium et entre l`oxyde d`uranium et le nitrure d`uranium

Energy Technology Data Exchange (ETDEWEB)

Lecraz, C

1993-06-11

A new type of combustible elements which is a mixture of uranium nitride and uranium-plutonium oxide could be used for Quick Neutrons Reactors. Three different studies have been made on the one hand on the reactions between uranium nitride (UN) and uranium-plutonium mixed oxide (U,Pu)O{sub 2}, on the other hand on these between UN and uranium oxide UO{sub 2}. They show a sizeable reaction between nitride and oxide for the studied temperatures range (1573 K to 1973 K). This reaction forms a oxynitride compound, MO{sub x} N{sub y} with M=U or M=(U,Pu), whose crystalline structure is similar to oxide`s. Solubility of nitride in both oxides is studied, as the reaction kinetics. (TEC). 32 refs., 48 figs., 22 tabs.

Uranium rich granite and uranium productive granite in south China

Energy Technology Data Exchange (ETDEWEB)

Mingyue, Feng; Debao, He [CNNC Key Laboratory of Uranium Resource Exploration and Evaluation Technology, Beijing Research Institute of Uranium Geology (China)

2012-07-15

The paper briefly introduces the differences between uranium rich granite and uranium productive granite in the 5 provinces of South China, and discusses their main characteristics in 4 aspects, the uranium productive granite is highly developed in fracture, very strong in alteration, often occurred as two-mica granite and regularly developed with intermediate-basic and acid dikes. The above characteristics distinguish the uranium productive granite from the uranium rich granite. (authors)

Uranium rich granite and uranium productive granite in south China

International Nuclear Information System (INIS)

Feng Mingyue; He Debao

2012-01-01

The paper briefly introduces the differences between uranium rich granite and uranium productive granite in the 5 provinces of South China, and discusses their main characteristics in 4 aspects, the uranium productive granite is highly developed in fracture, very strong in alteration, often occurred as two-mica granite and regularly developed with intermediate-basic and acid dikes. The above characteristics distinguish the uranium productive granite from the uranium rich granite. (authors)

Analysis on uranium mineralization-formation condition and prospecting potential in Xidamingshan metallogenic belt

International Nuclear Information System (INIS)

Li Zhixing; Qi Fucheng; He Zhongbo; Zhang Zilong

2012-01-01

There are many different opinions about the source of uranium and metallogenic mechanism in Xidamingshan metallogenic belt. therefore it blocked uranium resources potential evaluation and ore exploration. Through absorb in- formation and investigate Daxin deposit and systematic analysis on samples. It is believed that uranium source mainly came from Cambrian System, a little came from the deep. The Devonian System is favorable room for saving ores in addition to be pre-concentrated room for uranium. Also, there are new cognition about uranium metallogenic mechanism, establish ore-forming series of Xidamingshan metallogenic belt, It is proposed that uranium mineralization have experienced 4 stages; It is cleared that hydrothermal fluid superposition transform type uranium deposit is main genetic type, ancient karst accumulate type is secondary genetic type, the later is formed by leaching the former and then precipitate, enrichment in ancient karst congeries, which is formed nearby faults and with the movement of Xishan structural movement. It is proven that metallogenic potential of Xidamingshan metallogenic belt is good. Tectonic rock controlled by subsidiary fracture nearby regional main fault, which connected with the Cambrian System and the Devonian System, and the deep of the deposit is guideline of mineral prospecting next stage. (authors)

Uranium industry annual 1996

International Nuclear Information System (INIS)

1997-04-01

The Uranium Industry Annual 1996 (UIA 1996) provides current statistical data on the US uranium industry's activities relating to uranium raw materials and uranium marketing. The UIA 1996 is prepared for use by the Congress, Federal and State agencies, the uranium and nuclear electric utility industries, and the public. Data on uranium raw materials activities for 1987 through 1996 including exploration activities and expenditures, EIA-estimated reserves, mine production of uranium, production of uranium concentrate, and industry employment are presented in Chapter 1. Data on uranium marketing activities for 1994 through 2006, including purchases of uranium and enrichment services, enrichment feed deliveries, uranium fuel assemblies, filled and unfilled market requirements, uranium imports and exports, and uranium inventories are shown in Chapter 2. A feature article, The Role of Thorium in Nuclear Energy, is included. 24 figs., 56 tabs

Uranium industry annual 1996

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-04-01

The Uranium Industry Annual 1996 (UIA 1996) provides current statistical data on the US uranium industry`s activities relating to uranium raw materials and uranium marketing. The UIA 1996 is prepared for use by the Congress, Federal and State agencies, the uranium and nuclear electric utility industries, and the public. Data on uranium raw materials activities for 1987 through 1996 including exploration activities and expenditures, EIA-estimated reserves, mine production of uranium, production of uranium concentrate, and industry employment are presented in Chapter 1. Data on uranium marketing activities for 1994 through 2006, including purchases of uranium and enrichment services, enrichment feed deliveries, uranium fuel assemblies, filled and unfilled market requirements, uranium imports and exports, and uranium inventories are shown in Chapter 2. A feature article, The Role of Thorium in Nuclear Energy, is included. 24 figs., 56 tabs.

Production of sized particles of uranium oxides and uranium oxyfluorides

International Nuclear Information System (INIS)

Knudsen, I.E.; Randall, C.C.

1976-01-01

A process is claimed for converting uranium hexafluoride (UF 6 ) to uranium dioxide (UO 2 ) of a relatively large particle size in a fluidized bed reactor by mixing uranium hexafluoride with a mixture of steam and hydrogen and by preliminary reacting in an ejector gaseous uranium hexafluoride with steam and hydrogen to form a mixture of uranium and oxide and uranium oxyfluoride seed particles of varying sizes, separating the larger particles from the smaller particles in a cyclone separator, recycling the smaller seed particles through the ejector to increase their size, and introducing the larger seed particles from the cyclone separator into a fluidized bed reactor where the seed particles serve as nuclei on which coarser particles of uranium dioxide are formed. 9 claims, 2 drawing figures

Uranium 2000 : International symposium on the process metallurgy of uranium

International Nuclear Information System (INIS)

Ozberk, E.; Oliver, A.J.

2000-01-01

The International Symposium on the Process Metallurgy of Uranium has been organized as the thirtieth annual meeting of the Hydrometallurgy Section of the Metallurgical Society of the Canadian Institute of Mining, Metallurgy and Petroleum (CIM). This meeting is jointly organized with the Canadian Mineral Processors Division of CIM. The proceedings are a collection of papers from fifteen countries covering the latest research, development, industrial practices and regulatory issues in uranium processing, providing a concise description of the state of this industry. Topics include: uranium industry overview; current milling operations; in-situ uranium mines and processing plants; uranium recovery and further processing; uranium leaching; uranium operations effluent water treatment; tailings disposal, water treatment and decommissioning; mine decommissioning; and international regulations and decommissioning. (author)

Analogue studies in the alligator rivers region. In-situ measurement of uranium series nuclides with SHRIMP

Energy Technology Data Exchange (ETDEWEB)

Nagano, Tetsushi; Yanase, Nobuyuki; Ohnuki, Toshihiko [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Sato, Tsutomu; Isobe, Hiroshi; Williams, I.S.; Zaw, M.; Payne, T.E.; Airey, P.L.

1999-03-01

The SHRIMP analyses have been conducted for rock samples from the Koongarra secondary ore deposit to obtain activity ratios of {sup 234}U/{sup 238}U and isotopic ratios of {sup 207}Pb/{sup 206}Pb and {sup 204}Pb/{sup 206}Pb. Target minerals for the analyses were iron minerals and kaolinite, which are the main weathering products in this area. The activity ratios of {sup 234}U/{sup 238}U were obtained based on counts at masses of uranium metal. The {sup 234}U/{sup 238}U activity ratios based on counts of uranium oxides were not appropriate, because count rates of {sup 234}U{sup 16}O were interfered by those of {sup 238}U{sup 12}C molecule. The activity ratios of {sup 234}U/{sup 238}U were approximately unity for crystalline iron nodules. This fact suggested that the mean residence time of uranium within the iron nodules was at least 1 million years. On the other hand, slightly higher values than unity were obtained for kaolinite. Lead isotopes were investigated and a positive relationship was recognized between {sup 207}Pb/{sup 206}Pb and {sup 204}Pb/{sup 206}Pb isotope ratios. (author)

Fission blanket benchmark experiment on spherical assembly of uranium and PE with PE reflector

Energy Technology Data Exchange (ETDEWEB)

Zhu, Tonghua; Lu, Xinxin; Wang, Mei; Han, Zijie, E-mail: neutron_integral@aliyun.com; Jiang, Li; Wen, Zhongwei; Liu, Rong

2016-04-15

Highlights: • The fission rate distribution on two depleted uranium assemblies was measured with plate fission chambers. • We do calculations using MCNP code and ENDF/B-V.0 library. • The overestimation of calculations to the measured fission rates was found. • The observed discrepancy are discussed. - Abstract: New concept of fusion-fission hybrid for energy generation has been proposed. To validate the nuclear performance of fission blanket of hybrid, as part of series of validation experiment, two types of fission blanket assemblies were setup in this work and measurements were made of the reaction rate distribution for uranium fission in the spherical assembly of depleted uranium and polyethylene by Plate Fission Chamber (PFC). There are two PFCs in experiment, one is depleted uranium chamber and the other is enriched uranium chamber. The Monte-Carlo transport code MCNP5 and continuous energy cross sections library ENDF/BV.0 were used for the analysis of fission rate distribution in the two types of assemblies. The calculated results were compared with the experimental ones. The overestimation of fission rate for depleted uranium and enriched uranium were found in the inner boundary of the two assemblies. However, the C/E ratio tends to decrease for the distance from the core slightly and the results for enriched uranium are better than that for depleted uranium.

Evolution of ore-bearing material sources of endogenous uranium deposits

International Nuclear Information System (INIS)

Kazansk, V.I.; Laverov, N.P.; Tugarinov, A.I.

1976-01-01

Considered are the regularities of changes in types and conditions of uranium deposit formation in connection with the general development of the earth crust tectonic structures. Out of pre-Kembrian uranium deposits considered are Vitwatersrand conglomerates, hydrothermal deposits in pre-Kembrian iron quartzites in the areas of regional fractures in exocontacts of big multiphase granitoid massifs of Proterozoic age and in the fundament folded structures. The hydrothermal-metamorphogen theory is supported of the origin of uranium-bearing sodium metasomatite of Proterozoic, including uranium deposits in the area of the Atabaska lake. Four genetic classes of Palaeozoic deposits are considered. Four periods are singled out in the development of Palaeozoic uranium provinces. Most of the Palaeozoic deposits are shown to be of polygenous origin. Mesozoic deposits are also polygenous, but the combination of ore substance sources in them is more complex

Meso-cenozoic extensional tectonics and uranium metallogenesis in southeast China

International Nuclear Information System (INIS)

Chen Yuehui; Chen Zuyi; Cai Yuqi; Fu Jin; Feng Quanhong; Shi Zuhai

1998-12-01

Through a systematic study on Meso-Cenozoic extensional tectonics in Southeast China, the authors point out that there are three major types of extensional tectonics such as taphrogenic thermo-upwelling, and gravitational extensional tectonics. The characteristics of structural forms, combination patterns, movement style and syn-tectonic magmatism of different extensional tectonics are studied. Then according to the known isotope age data of uranium mineralizations in the area, the relations between the process of extensional tectonics and regional uranium metallogenesis, as well as the corresponding relations in space and time between extensional tectonics and uranium deposits of different types are analyzed. In conclusion, the authors suggest that the uranium mineralizations of different types in Southeast China are characterized by an united ore-forming mechanism due to the apparent control of extensional tectonics to the regional uranium metallogenesis

Mobility of elevated levels of uranium in the environment

International Nuclear Information System (INIS)

Miera, F.R. Jr.; Hanson, W.C.; Gladney, E.S.; Jose, P.

1980-01-01

Studies of the long-term consequences of exposing terrestrial ecosystems to aged deposits of natural and depleted uranium at Los Alamos Scientific Laboratory (LASL) have been conducted over the past 3 years. The E-F explosive testing site at LASL was selected for intensive study of uranium redistribution during its 24-year use. The highest surface-soil (0 to 2.5 cm) uranium concentrations occurred 0 to 10 m from the detonation point and average 4500 μg/g. Concentrations in surface soil 50 and 200 m from the detonation point were generally less than 15% of that value. The uranium distribution to 30-cm depths for the 0- to 50-m distant sampling locations and to 10-cm depths at 50- to 200-m sampling distances showed significant penetration into the soil profile. Ratios of plant/soil uranium concentrations varied from 0.05 to 0.08. Internal tissues from two species of small mammals had tissue/soil ratios of 10 -3 and 10 -4

U-series dating of Paleolithic art in 11 caves in Spain.

Science.gov (United States)

Pike, A W G; Hoffmann, D L; García-Diez, M; Pettitt, P B; Alcolea, J; De Balbín, R; González-Sainz, C; de las Heras, C; Lasheras, J A; Montes, R; Zilhão, J

2012-06-15

Paleolithic cave art is an exceptional archive of early human symbolic behavior, but because obtaining reliable dates has been difficult, its chronology is still poorly understood after more than a century of study. We present uranium-series disequilibrium dates of calcite deposits overlying or underlying art found in 11 caves, including the United Nations Educational, Scientific, and Cultural Organization (UNESCO) World Heritage sites of Altamira, El Castillo, and Tito Bustillo, Spain. The results demonstrate that the tradition of decorating caves extends back at least to the Early Aurignacian period, with minimum ages of 40.8 thousand years for a red disk, 37.3 thousand years for a hand stencil, and 35.6 thousand years for a claviform-like symbol. These minimum ages reveal either that cave art was a part of the cultural repertoire of the first anatomically modern humans in Europe or that perhaps Neandertals also engaged in painting caves.

Forecasting sandstone uranium deposits in oil-and-gas bearing basins

International Nuclear Information System (INIS)

Pechenkin, I.

2014-01-01

The interrelation between oxidation and reduction processes in the carbonaceous strata of Paleogene age was first studied in the 1950s in deposit of the Fergana depression. The presence of pre-ore and post-ore epigenesis of petroleum series was established. Part of uranium mineralization was found to be covered with fluid oil. In the middle of the 1960s in the Sabirsay deposit (Uzbekistan) in primary red-coloured continental sediment of Cretaceous age were studied pre-ore reduction changes, which caused economic uranium mineralization in contrasting geochemical barrier. Further research showed that multidirectional epigenetic processes had changed repeatedly. Later, in the 1970s, American geologists studying uranium deposits in the oil-and-gas bearing Texas Plain reached similar conclusions. From their point of view, in the Benevides deposit the main zones of mineralization tend to be located near the boundary where the zones of oxidation in the strata wedge in, developing in epigenetically reduced formations. A second post-mineral reduction was registered in a number of rock bodies. The complexity of the processes is determined by the double role of hydrocarbon fluids and the products of their dissolution. On the one hand, bituminization of permeable strata as well as pyritization, chloritization, dolomitization and other alterations associated with it create favourable geochemical conditions of a reducing character for a subsequent concentration of ore and nonmetal raw materials. On the other hand, intrusion of bitumen and its dissolution in the aeration zone leads to the burial of the mineralization which formed earlier and disappearance of all traces of its formation (epigenetic oxidation zoning). Thus forecasting and subsequent prospecting become impeded. The established sequence of epigenetic alterations allows us to carry out specialized mapping in productive regions, uncovering hidden parts of epigenetic oxidation zoning and “buried” mineralization

Uranium Industry Annual, 1992

International Nuclear Information System (INIS)

1993-01-01

The Uranium Industry Annual provides current statistical data on the US uranium industry for the Congress, Federal and State agencies, the uranium and electric utility industries, and the public. The feature article, ''Decommissioning of US Conventional Uranium Production Centers,'' is included. Data on uranium raw materials activities including exploration activities and expenditures, resources and reserves, mine production of uranium, production of uranium concentrate, and industry employment are presented in Chapter 1. Data on uranium marketing activities including domestic uranium purchases, commitments by utilities, procurement arrangements, uranium imports under purchase contracts and exports, deliveries to enrichment suppliers, inventories, secondary market activities, utility market requirements, and uranium for sale by domestic suppliers are presented in Chapter 2

Uranium Industry Annual, 1992

Energy Technology Data Exchange (ETDEWEB)

1993-10-28

The Uranium Industry Annual provides current statistical data on the US uranium industry for the Congress, Federal and State agencies, the uranium and electric utility industries, and the public. The feature article, ``Decommissioning of US Conventional Uranium Production Centers,`` is included. Data on uranium raw materials activities including exploration activities and expenditures, resources and reserves, mine production of uranium, production of uranium concentrate, and industry employment are presented in Chapter 1. Data on uranium marketing activities including domestic uranium purchases, commitments by utilities, procurement arrangements, uranium imports under purchase contracts and exports, deliveries to enrichment suppliers, inventories, secondary market activities, utility market requirements, and uranium for sale by domestic suppliers are presented in Chapter 2.

Preliminary study of favorability for uranium resources in Juab County, Utah

International Nuclear Information System (INIS)

Leedom, S.H.; Mitchell, T.P.

1978-02-01

The best potential for large, low-grade uranium deposits in Juab County is in the hydrothermally altered vitric tuffs of Pliocene age. The lateral extent of the altered tuffs may be determined by subsurface studies around the perimeter of the volcanic centers in the Thomas Range and the Honeycomb Hills. Because the ring-fracture zone associated with collapse of the Thomas caldera was a major control for hydrothermal uranium deposits, delineation of the northern and eastern positions of the ring-fracture zone is critical in defining favorable areas for uranium deposits. A small, medium-grade ore deposit in tuffaceous sand of Pliocene age at the Yellow Chief mine in Dugway Dell is unique in origin, and the probability of discovering another deposit of this type is low. A deposit of this type may be present under alluvial cover in the northwestern Drum Mountains along the southern extension of the ring-fracture zone of the Thomas caldera. Festoonlike iron oxide structures and uranium deposition within permeable sandstone horizons indicate that the Yellow Chief deposit was formed by recent ground-water circulation. Granitic intrusive rocks in the Deep Creek Range and in Desert Mountain contain isolated epigenetic vein-type deposits. These rocks could be a source of arkosic sediments buried in adjacent valleys. The Pleistocene lacustrine sediments and playa lake brines may contain concentrations of uranium leached from uranium-rich rocks

Depleted uranium

International Nuclear Information System (INIS)

Huffer, E.; Nifenecker, H.

2001-02-01

This document deals with the physical, chemical and radiological properties of the depleted uranium. What is the depleted uranium? Why do the military use depleted uranium and what are the risk for the health? (A.L.B.)

Pyrophoric behaviour of uranium hydride and uranium powders

Science.gov (United States)

Le Guyadec, F.; Génin, X.; Bayle, J. P.; Dugne, O.; Duhart-Barone, A.; Ablitzer, C.

2010-01-01

Thermal stability and spontaneous ignition conditions of uranium hydride and uranium metal fine powders have been studied and observed in an original and dedicated experimental device placed inside a glove box under flowing pure argon. Pure uranium hydride powder with low amount of oxide (Oxidation mechanisms are proposed.

RECOVERY OF URANIUM FROM ZIRCONIUM-URANIUM NUCLEAR FUELS

Science.gov (United States)

Gens, T.A.

1962-07-10

An improvement was made in a process of recovering uranium from a uranium-zirconium composition which was hydrochlorinated with gsseous hydrogen chloride at a temperature of from 350 to 800 deg C resulting in volatilization of the zirconium, as zirconium tetrachloride, and the formation of a uranium containing nitric acid insoluble residue. The improvement consists of reacting the nitric acid insoluble hydrochlorination residue with gaseous carbon tetrachloride at a temperature in the range 550 to 600 deg C, and thereafter recovering the resulting uranium chloride vapors. (AEC)

R and D on laser uranium enrichment

International Nuclear Information System (INIS)

Anon.

1986-01-01

An AEC Advisory Committee on Uranium Enrichment has completed investigations into the actual condition of laser isotope separation. The working group set up for the purpose has issued a report on the series of investigations made on its development and measures for promoting it. The report says that the development of the process in Japan is at a fundamental stage. Noting that further efforts are needed before its future can be predicted, the report proposes a cource of research and development for the immediate future. For the atomic vapor laser isotope separation (AVLIS), government organizations are engaged in data base buildup and conducting basis engineering tests, and Japan Atomic Energy Research Institute will consider the re-enrichment of uranium recovered from reprocessing. Non-governmental unions of researchers will promote the combination of copper-vapor laser and dye laser. For the molecular laser isotope separation (MLIS), the Institute of Physical and Chemical Research will take up studies with the cooperation of the Power Reactor and Nuclear Fuel Development Corporation. In chapters covering the philosophy of laser uranium enrichment technology development, the report deals with its significance, actual conditions and tasks, and goals and measures for its promotion. (Nogami, K.)

Genesis of uranium deposits of the Tono Mine, Japan

International Nuclear Information System (INIS)

Katayama, N.; Kubo, K.; Hirono, S.

1974-01-01

The uranium deposits of the Tono mine, Gifu Prefecture, Japan, occur in the basal part of the Toki group of Miocene age, and are distributed in the tributaries or at the head of channels on the plane of unconformity under the formation. These features characterize the basal ground-water type of uranium deposit, and they are unique in that their typical ore mineral is a zeolite of the heulandite-clinoptilolite group, uranium being adsorbed in it. The paper presents the history of formation of the Tsukiyoshi deposits, the most intensely explored in the Tono mine. The matrices of conglomerates and sandstones of the Toki group usually contain tuffaceous material, which has been montmorillonitized or zeolitized diagenetically. The conduit of uranium-bearing ground waters that migrated from the basement granites into the Tertiary sediments was controlled by the impermeable barriers, which are rocks in which montmorillonite predominated, or by the Tsukiyoshi fault, as well as by channel structures. Where the waters became rather stagnant, uranium was adsorbed in zeolite from them. Enrichment of uranium further proceeded locally as follows. Pyrite was oxidized to produce sulphuric acid solution which leached the uranium that had been adsorbed in zeolite. The pH of the uranium-rich solution became higher and higher in the course of migration and, as soon as it reached about 4, the uranium in the solution was again adsorbed in zeolite, the uranium content of which may have been enriched up to 0.9%. Coffinites have been formed where uranium was accumulated over the adsorption capacity of zeolite or where strongly reducing conditions were maintained by carbonaceous matter. (author)

Recovery of uranium and molybdenum elements from gebel gattar raw material, eastern desert, Egypt. Vol. 3

Energy Technology Data Exchange (ETDEWEB)

El-Hazek, N T; Mahdy, M A; Mahmoud, H M.K. [Nuclear Materials Authority, Cairo, (Egypt)

1996-03-01

G. Gatter uranium mineralizations are located along the faults and fracture zones crossing G.Gattar granitic pluton and long the contact of the pluton with the hammamat sediments. Also, molybdenum id presented in more than one mode of occurrence. The molybdenum mineralization treated in this work is the dessimenated type. The uranium and molybdenum raw material was subjected to series of leaching experiments including acid and alkaline agitation, alkaline percolation, and acid heap leaching techniques. Recovery of uranium and molybdenum was achieved by anion-exchange method followed by their elution by acidified sodium chloride. Uranium precipitation was performed in the form of ammonium diuranate (Yellow Cake). On the other hand molybdenum was precipitated in the form of molybdenum oxide. A tentative flowsheet for the extraction of both uranium and molybdenum is proposed and discussed. 13 figs., 3 tabs.

Recovery of uranium and molybdenum elements from gebel gattar raw material, eastern desert, Egypt. Vol. 3

International Nuclear Information System (INIS)

El-Hazek, N.T.; Mahdy, M.A.; Mahmoud, H.M.K.

1996-01-01

G. Gatter uranium mineralizations are located along the faults and fracture zones crossing G.Gattar granitic pluton and long the contact of the pluton with the hammamat sediments. Also, molybdenum id presented in more than one mode of occurrence. The molybdenum mineralization treated in this work is the dessimenated type. The uranium and molybdenum raw material was subjected to series of leaching experiments including acid and alkaline agitation, alkaline percolation, and acid heap leaching techniques. Recovery of uranium and molybdenum was achieved by anion-exchange method followed by their elution by acidified sodium chloride. Uranium precipitation was performed in the form of ammonium diuranate (Yellow Cake). On the other hand molybdenum was precipitated in the form of molybdenum oxide. A tentative flowsheet for the extraction of both uranium and molybdenum is proposed and discussed. 13 figs., 3 tabs

New resin gel for uranium determination by diffusive gradient in thin films technique

International Nuclear Information System (INIS)

Gregusova, Michaela; Docekal, Bohumil

2011-01-01

A new resin gel based on Spheron-Oxin chelating ion-exchanger with anchored 8-hydroxyquinoline functional groups was tested for application in diffusive gradient in thin film technique (DGT) for determination of uranium. Selectivity of uranium uptake from model carbonate loaded solutions of natural water was studied under laboratory conditions and compared with selectivity of the conventional Chelex 100 based resin gel. The affinity of Spheron-Oxin functional groups enables determination of the overall uranium concentration in water containing carbonates up to the concentration level of 10 2 mg L -1 . The effect of uranium binding to the polyacrylamide (APA) and agarose diffusive gels (AGE) was also studied. Uranium is probably bound in both gels by a weak interaction with traces of acrylic acid groups in the structure of APA gel and with pyruvic and sulfonic acid groups in the AGE gel. These sorption effects can be eliminated to the negligible level by prolonged deployment of DGT probes or by disassembling probes after the 1-2 days post-sampling period that is sufficient for release of uranium from diffusive gel and its sorption in resin gel.

New resin gel for uranium determination by diffusive gradient in thin films technique

Energy Technology Data Exchange (ETDEWEB)

Gregusova, Michaela, E-mail: gregusova@iach.cz [Institute of Analytical Chemistry, Academy of Sciences of the Czech Republic v.v.i., Veveri 97, 602 00 Brno (Czech Republic); Docekal, Bohumil [Institute of Analytical Chemistry, Academy of Sciences of the Czech Republic v.v.i., Veveri 97, 602 00 Brno (Czech Republic)

2011-01-17

A new resin gel based on Spheron-Oxin chelating ion-exchanger with anchored 8-hydroxyquinoline functional groups was tested for application in diffusive gradient in thin film technique (DGT) for determination of uranium. Selectivity of uranium uptake from model carbonate loaded solutions of natural water was studied under laboratory conditions and compared with selectivity of the conventional Chelex 100 based resin gel. The affinity of Spheron-Oxin functional groups enables determination of the overall uranium concentration in water containing carbonates up to the concentration level of 10{sup 2} mg L{sup -1}. The effect of uranium binding to the polyacrylamide (APA) and agarose diffusive gels (AGE) was also studied. Uranium is probably bound in both gels by a weak interaction with traces of acrylic acid groups in the structure of APA gel and with pyruvic and sulfonic acid groups in the AGE gel. These sorption effects can be eliminated to the negligible level by prolonged deployment of DGT probes or by disassembling probes after the 1-2 days post-sampling period that is sufficient for release of uranium from diffusive gel and its sorption in resin gel.

Uranium prospecting; La prospection de l'uranium

Energy Technology Data Exchange (ETDEWEB)

Roubault, M. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1955-07-01

This report is an instruction book for uranium prospecting. It appeals to private prospecting. As prospecting is now a scientific and technical research, it cannot be done without preliminary studies. First of all, general prospecting methods are given with a recall of fundamental geologic data and some general principles which are common with all type of prospecting. The peculiarities of uranium prospecting are also presented and in particular the radioactivity property of uranium as well as the special aspect of uranium ores and the aspect of neighbouring ores. In a third part, a description of the different uranium ores is given and separated in two different categories: primary and secondary ores, according to the place of transformation, deep or near the crust surface respectively. In the first category, the primary ores include pitchblende, thorianite and rare uranium oxides as euxenite and fergusonite for example. In the second category, the secondary ores contain autunite and chalcolite for example. An exhaustive presentation of the geiger-Mueller counter is given with the presentation of its different components, its functioning and utilization and its maintenance. The radioactivity interpretation method is showed as well as the elaboration of a topographic map of the measured radioactivity. A brief presentation of other detection methods than geiger-Mueller counters is given: the measurement of fluorescence and a chemical test using the fluorescence properties of uranium salts. Finally, the main characteristics of uranium deposits are discussed. (M.P.)

Contribution to the study of nuclear fuel materials with a metallic uranium base; Contribution a l'etude des materiaux combustibles nucleaires a base d'uranium metallique

Energy Technology Data Exchange (ETDEWEB)

Englander, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1957-11-15

In a power reactor destined to supply industrially recoverable thermal energy, the most economical source of heat still consists of natural metallic uranium. However, the nuclear fuel material, most often employed in the form of rods of 20 to 40 mm diameter, is subjected to a series of stresses which lead to irreversible distortions usually incompatible with the substructure of the reactor. As a result the fuel material must possess at the outset a certain number of qualities which must be determined. Investigations have therefore been carried out, first on the technological characters peculiar to each of the three allotropic phases of pure uranium metal, and on their interactions on the stabilisation of the material which consists of either cast uranium or uranium pile-treated in the {gamma} phase. (author) [French] Dans un reacteur de puissance destine a fournir de l'energie thermique industriellement recuperable, la source de chaleur la plus economique reste constituee par de l'uranium metallique naturel. Or, le materiau combustible nucleaire, employe le plus souvent sous forme de barreaux de 20 a 40 mm de diametre, se trouve soumis a un ensemble de contraintes qui provoque des deformations irreversibles, le plus souvent incompatibles avec l'infrastructure du reacteur. Par consequent, le materiau combustible doit presenter a l'origine un certain nombre de qualites qu'il est necessaire de determiner. Aussi a-t-on d'abord etudie les caracteres technologiques propres a chacune des trois phases allotropiques de l'uranium-metal pur et leurs interactions sur la stabilisation du materiau constitue soit par de l'uranium coule, soit par de l'uranium traite en pile en phase {gamma}. (auteur)

National Uranium Resource Evaluation: Hutchinson Quadrangle, Kansas

International Nuclear Information System (INIS)

Fair, C.L.; Smit, D.E.; Gundersen, J.N.

1982-08-01

Surface reconnaissance and detailed subsurface studies were done within the Hutchinson Quadrangle, Kansas, to evaluate uranium favorability in accordance with National Uranium Resource Evaluation criteria. These studies were designed in part to follow up prior airborne radiometric, hydrogeochemical, and stream-sediment surveys. Over 4305 well records were examined in the subsurface phase of this study. The results of these investigations indicate environments favorable for channel-controlled peneconcordant sandstone deposits in rocks of Cretaceous age and for Wyoming and Texas roll-type deposits in sandstones of Pennsylvanian age. The Cretaceous sandstone environments exhibit favorable characteristics such as a bottom unconformity; high bedload; braided, fluvial channels; large-scale cross-bedding; and an anomalous outcrop. The Pennsylvanian sandstone environments exhibit favorable characteristics such as arkosic cross-bedded sandstones, included pyrite and organic debris, interbedded shales, and gamma-ray log anomalies. Environments considered unfavorable for uranium deposits are limestone and dolomite environments, marine black shale environments, evaporative precipitate environments, and some fluvial sandstone environments. Environments considered unevaluated due to insufficient data include Precambrian plutonic, metamorphic, and sedimentary rocks, even though a large number of thin sections were available for study

Uranium health physics

International Nuclear Information System (INIS)

1980-01-01

This report contains the papers delivered at the Summer School on Uranium Health Physics held in Pretoria on the 14 and 15 April 1980. The following topics were discussed: uranium producton in South Africa; radiation physics; internal dosimetry and radiotoxicity of long-lived uranium isotopes; uranium monitoring; operational experience on uranium monitoring; dosimetry and radiotoxicity of inhaled radon daughters; occupational limits for inhalation of radon-222, radon-220 and their short-lived daughters; radon monitoring techniques; radon daughter dosimeters; operational experience on radon monitoring; and uranium mill tailings management

Uranium supply and demand

Energy Technology Data Exchange (ETDEWEB)

Spriggs, M J

1976-01-01

Papers were presented on the pattern of uranium production in South Africa; Australian uranium--will it ever become available; North American uranium resources, policies, prospects, and pricing; economic and political environment of the uranium mining industry; alternative sources of uranium supply; whither North American demand for uranium; and uranium demand and security of supply--a consumer's point of view. (LK)

Sandstone-type uranium deposits. Summary and conclusions

International Nuclear Information System (INIS)

Finch, W.I.

1985-01-01

The similarity of most of the deposits described in this report is striking even though they occur in sandstone host rocks ranging in age from Carboniferous to Tertiary and on every continent outside the polar regions. Geologic environments of the uranium deposits consist of distinctive sets of tectonic and sedimentary-depositional systems, all of which have some common threads of favorable geologic processes. In this summary paper it is hoped that this report has sharpened an understanding of the deposit's ''home environment'' that will aid future exploration for these resource-important sandstone-type uranium ores

Uranium industry annual, 1991

International Nuclear Information System (INIS)

1992-10-01

In the Uranium Industry Annual 1991, data on uranium raw materials activities including exploration activities and expenditures, resources and reserves, mine production of uranium, production of uranium concentrate, and industry employment are presented in Chapter 1. Data on uranium marketing activities including domestic uranium purchases, commitments by utilities, procurement arrangements, uranium imports under purchase contracts and exports, deliveries to enrichment suppliers, inventories, secondary market activities, utility market requirements, and uranium for sale by domestic suppliers are presented in Chapter 2. A feature article entitled ''The Uranium Industry of the Commonwealth of Independent States'' is included in this report

Uranium isotopes and dissolved organic carbon in loess permafrost: Modeling the age of ancient ice

Science.gov (United States)

Ewing, Stephanie A.; Paces, James B.; O'Donnell, J.A.; Jorgenson, M.T.; Kanevskiy, M.Z.; Aiken, George R.; Shur, Y.; Harden, Jennifer W.; Striegl, Robert G.

2015-01-01

The residence time of ice in permafrost is an indicator of past climate history, and of the resilience and vulnerability of high-latitude ecosystems to global change. Development of geochemical indicators of ground-ice residence times in permafrost will advance understanding of the circumstances and evidence of permafrost formation, preservation, and thaw in response to climate warming and other disturbance. We used uranium isotopes to evaluate the residence time of segregated ground ice from ice-rich loess permafrost cores in central Alaska. Activity ratios of 234U vs. 238U (234U/238U) in water from thawed core sections ranged between 1.163 and 1.904 due to contact of ice and associated liquid water with mineral surfaces over time. Measured (234U/238U) values in ground ice showed an overall increase with depth in a series of five neighboring cores up to 21 m deep. This is consistent with increasing residence time of ice with depth as a result of accumulation of loess over time, as well as characteristic ice morphologies, high segregated ice content, and wedge ice, all of which support an interpretation of syngenetic permafrost formation associated with loess deposition. At the same time, stratigraphic evidence indicates some past sediment redistribution and possibly shallow thaw among cores, with local mixing of aged thaw waters. Using measures of surface area and a leaching experiment to determine U distribution, a geometric model of (234U/238U) evolution suggests mean ages of up to ∼200 ky BP in the deepest core, with estimated uncertainties of up to an order of magnitude. Evidence of secondary coatings on loess grains with elevated (234U/238U) values and U concentrations suggests that refinement of the geometric model to account for weathering processes is needed to reduce uncertainty. We suggest that in this area of deep ice-rich loess permafrost, ice bodies have been preserved from the last glacial period (10–100 ky BP), despite subsequent

230Th/U-dating of a late Holocene low uranium speleothem from Cuba