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Sample records for bedrock uranium 238u

  1. 238U, and its decay products, in grasses from an abandoned uranium mine

    Science.gov (United States)

    Childs, Edgar; Maskall, John; Millward, Geoffrey

    2016-04-01

    Bioaccumulation of radioactive contaminants by plants is of concern particularly where the sward is an essential part of the diet of ruminants. The abandoned South Terras uranium mine, south west England, had primary deposits of uraninite (UO2) and pitchblende (U3O8), which contained up to 30% uranium. When the mine was active uranium and radium were extracted but following closure it was abandoned without remediation. Waste rock and gangue, consisting of inefficiently processed minerals, were spread around the site, including a field where ruminants are grazed. Here we report the activity concentrations of 238U, 235U 214,210Pb, and the concentrations of selected metals in the soils, roots and leaves of grasses taken from the contaminated field. Soil samples were collected at the surface, and at 30 cm depth, using an auger along a 10-point transect in the field from the foot of a waste heap. Whole, individual grass plants were removed with a spade, ensuring that their roots were intact. The soils and roots and grass leaves were freeze-dried. Activity concentrations of the radionuclides were determined by gamma spectroscopy, following 30 days incubation for development of secular equilibrium. Dried soils, roots and grasses were also digested in aqua regia and the concentrations of elements determined by ICP techniques. Maximum activity concentrations of 238U, 235U, 214Pb and 210Pb surface soils were 63,300, 4,510, 23,300 and 49,400 Bq kg-1, respectively. The mean 238U:235U ratio was 11.8 ± 1.8, an order of magnitude lower than the natural value of 138, indicating disequilibrium within the decay chain due to mineral processing. Radionuclides in the roots had 5 times lower concentration and only grass leaves in the vicinity of the waste heap had measureable values. The mean soil to root transfer factor for 238U was 36%, the mean root to leaf was 3% and overall only 0.7% of 238U was transferred from the soil to the leaves. The roots contained 0.8% iron, possibly as

  2. Determination of the isotopic ratio {sup 234} U/{sup 238} U and {sup 235} U/{sup 238} U in uranium commercial reagents by alpha spectroscopy; Determinacion de la relacion isotopica {sup 234} U/{sup 238} U y {sup 235} U/{sup 238} U en reactivos comerciales de uranio por espectrometria alfa

    Energy Technology Data Exchange (ETDEWEB)

    Iturbe G, J.L

    1990-02-15

    In this work the determination of the isotope ratio {sup 234} U/{sup 238} U and {sup 235} U/{sup 238} U obtained by means of the alpha spectroscopy technique in uranium reagents of commercial marks is presented. The analyzed uranium reagents were: UO{sub 2} (*) nuclear purity, UO{sub 3} (*) poly-science, metallic uranium, uranyl nitrate and uranyl acetate Merck, uranyl acetate and uranyl nitrate Baker, uranyl nitrate (*) of the Refinement and Conversion Department of the ININ, uranyl acetate (*) Medi-Lab Sigma of Mexico and uranyl nitrate Em Science. The obtained results show that the reagents that are suitable with asterisk (*) are in radioactive balance among the one {sup 234} U/{sup 238} U, since the obtained value went near to the unit. In the case of the isotope ratio {sup 235} U/{sup 238} U the near value was also obtained the one that marks the literature that is to say 0.04347, what indicates that these reagents contain the isotope of {sup 235} U in the percentage found in the nature of 0.71%. The other reagents are in radioactive imbalance among the {sup 234} U/{sup 238} U, the found values fluctuated between 0.4187 and 0.1677, and for the quotient of activities {sup 235} U/{sup 238} U its were of 0.0226, and the lowest of 0.01084. Also in these reagents it was at the {sup 236} U as impurity. The isotope of {sup 236} U is an isotope produced artificially, for what is supposed that the reagents that are in radioactive imbalance were synthesized starting from irradiated fuel. (Author)

  3. Investigation of the {sup 236}U/{sup 238}U isotope abundance ratio in uranium ores and yellow cake samples

    Energy Technology Data Exchange (ETDEWEB)

    Srncik, M. [Vienna Univ. (Austria). Dept. of Inorganic Chemistry; European Commission, Joint Research Centre, Karlsruhe (Germany). Institute for Transuranium Elements; Mayer, K.; Hrnecek, E.; Wallenius, M.; Varga, Z. [European Commission, Joint Research Centre, Karlsruhe (Germany). Institute for Transuranium Elements; Steier, P. [Vienna Univ. (Austria). VERA Lab.; Wallner, G. [Vienna Univ. (Austria). Dept. of Inorganic Chemistry

    2011-07-01

    Uranium ores and yellow cake samples of known geographic origin were investigated for their n({sup 236}U)/n({sup 238}U) isotope abundance ratio. Samples from four different uranium mines in Australia, Brazil and Canada were selected. Uranium was separated by UTEVA {sup registered} Resin and was measured by Accelerator Mass Spectrometry (AMS) at the Vienna Environmental Research Accelerator (VERA). The measurement of the isotope abundance ratio n({sup 236}U)/n({sup 238}U) will be used to investigate possible correlations between the original mineral (uranium ore) and the intermediate product (yellow cake). Such correlations are useful indicators for nuclear forensic or for non-proliferation purposes. (orig.)

  4. 238U and 235U isotope fractionation upon oxidation of uranium-bearing rocks by fracture waters

    Science.gov (United States)

    Chernyshev, I. V.; Golubev, V. N.; Chugaev, A. V.; Mandzhieva, G. V.

    2016-10-01

    The variations in 238U/235U values accompanying mobilization of U by fracture waters from uranium-bearing rocks, in which U occurs as a fine impregnation of oxides and silicates, were studied by the high-precision (±0.07‰) MC-ICP-MS method. Transition of U into the aqueous phase in the oxidized state U(VI) is accompanied by its isotope fractionation with enrichment of dissolved U(VI) in the heavy isotope 238U up to 0.32‰ in relation to the composition of the solid phases. According to the sign, this effect is consistent with the tendency of the behavior of 238U and 235U upon interaction of river waters with rocks of the catchment areas [11] and with the effect observed during oxidation of uraninite by the oxygen-bearing NaHCO3 solution [12].

  5. Measurement and analysis of the 238U(n, 2n) reaction rate in depleted uranium/polyethylene shells

    Institute of Scientific and Technical Information of China (English)

    YAN Xiao-Song; LIU Rong; LU Xin-Xin; JIANG Li; WEN Zhong-Wei; HAN Zi-Jie

    2012-01-01

    In order to check the conceptual design of the subcritical blanket in a fnsion-fission hybrid reactor,a depleted uranium/polyethylene simulation device with alternate shells has been established.The measurement of the 238U(n,2n) reaction rate was carried out using an activation technique,by measuring the 208 keV γ rays emitted from 237 U.The self-absorption of depleted uranium foils with different thicknesses was experimentally corrected.The distribution of the 238U(n,2n) reaction rate at 90° to the incident D+ beam was obtained,with uncertainty between 5.3% and 6.0%.The experiment was analyzed using MCNP5 code with the ENDF/BVI library,and the calculated results are all about 5% higher than the measured results.

  6. (234)U/(238)U signatures associated with uranium ore bodies: part 1 Ranger 3.

    Science.gov (United States)

    Lowson, Richard T; McIntyre, Mark G

    2013-04-01

    The Ranger 3 ore body is an early Proterozoic U ore body in the Alligator Rivers U province, Northern Territory, Australia. It has surface expression with a redox front located between 30 and 50 m below the surface. The ground water U concentration and (234)U/(238)U AR signature in the top 10 m of the weathered zone are reported for 357 samples collected over 4 wet seasons, at 5 depths, along a transect in-line with the hydraulic gradient and along the centre line of the ore body and its associated dispersion halo. The results show that the weathered zone displays a general U isotope feature for this type of ore body with the (234)U/(238)U AR for the ground water and amorphous phase of the solid matrix being less than 1. The ground water (234)U/(238)U AR is independent of the annual monsoonal climate and depth within the range surface to 10 m. In the vicinity of the U ore body the ground water (234)U/(238)U AR is 0.75 and is very similar to the (234)U/(238)U AR of the amorphous phase of the solid (0.76). The (234)U/(238)U ARs of the amorphous phase and ground water rise and separate to values of 0.88 and 1.02 at the end of the transect. The rise and separation in (234)U/(238)U AR are interpreted as evidence that the source of the U in the ground water is from the water-soluble sub-phase of the amorphous phase and that the ground water flow is too fast to allow the processes occurring across the solid-water interface to reach chemical equilibrium. The data set is a robust characterisation of the coarse and fine detail of the (234)U/(238)U AR signature in the weathered zone of U ore bodies.

  7. Uranium stable isotope fractionation in the Black Sea: Modern calibration of the 238U/235U paleo-redox proxy

    Science.gov (United States)

    Rolison, John M.; Stirling, Claudine H.; Middag, Rob; Rijkenberg, Micha J. A.

    2017-04-01

    The isotopic compositions of redox-sensitive metals, including uranium (U), in marine sediments have recently emerged as powerful diagnostic tracers of the redox state of the ancient ocean-atmosphere system. Reliable interpretation of sedimentary isotopic information requires a thorough understanding of the environmental controls on isotopic fractionation in modern anoxic environments before being applied to the paleo-record. In this study, the relationship between ocean anoxia and the isotopic fractionation of U was investigated in the water column and sediments of the Black Sea, the world's largest anoxic basin. Paired measurements of 238U/235U and U concentration, supported by other redox parameters, were obtained for water column and sediment samples collected during the 2013 GA04N GEOTRACES expedition to the Black Sea. Removal of U from the water column occurs during the redox transition of soluble U(VI) to relatively insoluble U(IV), resulting in up to 43% of U being removed from solution in euxinic bottom waters. Uranium reduction and removal is accompanied by a progressive shift in 238U/235U towards isotopically light values in the water column as heavier 238U is preferentially exported to sediments over lighter 235U. This gives rise to apparent isotope enrichment factors of ε = -0.63 ± 0.09‰ and ε = -0.84 ± 0.11‰ when U removal is modelled by Rayleigh and closed system equilibrium isotope fractionation, respectively. These ε values fall within the range determined for bacterial U reduction experiments, and together with a striking correlation between the distributions of U and H2S, implicate microbially-mediated U(VI)-U(IV) reduction as the primary mechanism controlling U isotopic shifts in the Black Sea. The 238U/235U of underlying sediments is related to the the 238U/235U of Black Sea bottom waters through the isotope enrichment factor of the U reduction reaction but the relationship between sedimentary and water column 238U/235U is complicated

  8. Uranium concentrations and 234U/238U activity ratios in fault-associated groundwater as possible earthquake precursors

    Science.gov (United States)

    Finkel, R. C.

    In order to assess the utility of uranium isotopes as fluid phase earthquake precursors, uranium concentrations and 234U/238U activity ratios have been monitored on a monthly or bimonthly basis in water from 24 wells and springs associated with Southern California fault zones. Uranium concentrations vary from 0.002 ppb at Indian Canyon Springs on the San Jacinto fault to 8.3 ppb at Lake Hughes well on the San Andreas fault in the Palmdale area. 234U/238U activity ratios vary from 0.88 at Agua Caliente Springs on the Elsinore fault to 5.4 at Niland Slab well on the San Andreas fault in the Imperial Valley. There was one large earthquake in the study area during 1979, the 15 October 1979 M=6.6 Imperial Valley earthquake. Correlated with this event, uranium concentrations varied by a factor of more than 60 and activity ratios by a factor of 3 at the Niland Slab site, about 70 km from the epicenter. At the other sites monitored, uranium concentrations varied in time, but with no apparent pattern, while uranium activity ratios remained essentially constant throughout the monitoring period.

  9. (234)U/(238)U signatures associated with uranium ore bodies: part 3 Koongarra.

    Science.gov (United States)

    Lowson, Richard T

    2013-04-01

    The Koongarra ore body is an early Proterozoic U ore body in the Alligator Rivers U province, Northern Territory, Australia. It has surface expression with a redox front located ∼30 m below the surface. The (234)U/(238)U activity ratios (AR) for the ground water and the amorphous phase of the solid have been analysed for the ore zone and dispersion halo as a function of depth. The results display a (234)U/(238)U AR signature with depth which may be common to all U ore bodies. The (234)U/(238)U AR is depressed below secular equilibrium in the weathered material above the redox front; rises significantly above secular equilibrium in the vicinity of the redox front; and is followed by a gradual decrease with depth below the redox front. The amplitude of the profile is a function of local conditions. A model is proposed for the signature in which oxidising waters preferentially leach the (234)U sites at the redox front due to preconditioning of the (234)U sites by α recoil during the decay of (23)(8)U to (23)(4)U. Mass balance requires the solid material left behind the redox front to have a (234)U/(238)U AR reduced below 1. Local second order effects may be superimposed on the signature. The signature may have application to calibrating scenarios for nuclear waste repositories, assisting in understanding historical climates, economic evaluation of U ore bodies and U exploration.

  10. (234)U/(238)U signatures associated with uranium ore bodies: part 2 Manyingee.

    Science.gov (United States)

    Lowson, Richard T; McIntyre, Mark G

    2013-04-01

    The Manyingee ore body is a roll-front U ore body located at depth in the Cretaceous sandstone sediments of a Proterozoic palaeo valley. It is located in a confined aquifer. The aquifer is recharged 4 km upstream by the Ashburton River. Groundwater samples were collected at and up to 4.7 km downstream of the ore body. The ground water (234)U/(238)U activity ratios (AR) were elevated to 1.86 in the vicinity of the ore body and then declined to 1.06 over the 4.7 km transect. The elevated (234)U/(238)U ARs are attributed to selective leaching of (234)U sites by oxidising waters, with α recoil as a necessary precursor to produce activated (234)U sites. Direct ejection into another phase following α recoil is considered to be a minor contributor to (234)U -(238)U disequilibrium in this environment. The profile is considered to be typical of the (234)U/(238)U AR profile at and down gradient of the redox front of a U ore body.

  11. Polonium 210Po, uranium (234U, 238U and plutonium (238Pu, 239+240Pu bioaccumulation in marine birds

    Directory of Open Access Journals (Sweden)

    Strumińska-Parulska D. I.

    2013-04-01

    Full Text Available The aim of this work was the determination of 210Po, 234U, 238U, 238Pu and 239+240Pu concentration in marine birds which permanently or temporally live in the southern Baltic Sea coast. We chose 11 species of seabirds: three species permanently residing at southern Baltic Sea, four species of wintering birds and three species of migrating birds. The results show that analyzed radionuclides are non-uniformly distributed in the marine birds. The highest activities of 210Po were observed in feathers, muscles and liver. The highest uranium content was found in liver, rest of viscera and feathers, while plutonium in the digestion organs and feathers. Omnivore seabirds accumulated more polonium, plutonium than species that feed on fish, while herbivore seabirds accumulated more uranium than carnivore.

  12. Reactive transport of uranium in a groundwater bioreduction study: Insights from high-temporal resolution 238U/235U data

    Science.gov (United States)

    Shiel, A. E.; Johnson, T. M.; Lundstrom, C. C.; Laubach, P. G.; Long, P. E.; Williams, K. H.

    2016-08-01

    We conducted a detailed investigation of U isotopes in conjunction with a broad geochemical investigation during field-scale biostimulation and desorption experiments. This investigation was carried out in the uranium-contaminated alluvial aquifer of the Rifle field research site. In this well-characterized setting, a more comprehensive understanding of U isotope geochemistry is possible. Our results indicate that U isotope fractionation is consistently observed across multiple experiments at the Rifle site. Microbially-mediated reduction is suggested to account for most or all of the observed fractionation as abiotic reduction has been demonstrated to impart much smaller, often near-zero, isotopic fractionation or isotopic fractionation in the opposite direction. Data from some time intervals are consistent with a simple model for transport and U(VI) reduction, where the fractionation factor (ε = +0.65‰ to +0.85‰) is consistent with experimental studies. However, during other time intervals the observed patterns in our data indicate the importance of other processes in governing U concentrations and 238U/235U ratios. For instance, we demonstrate that departures from Rayleigh behavior in groundwater systems arise from the presence of adsorbed species. We also show that isotope data are sensitive to the onset of oxidation after biostimulation ends, even in the case where reduction continues to remove contaminant uranium downstream. Our study and the described conceptual model support the use of 238U/235U ratios as a tool for evaluating the efficacy of biostimulation and potentially other remedial strategies employed at Rifle and other uranium-contaminated sites.

  13. A study on possible use of Urtica dioica (common nettle) plants as uranium ((234)U, (238)U) contamination bioindicator near phosphogypsum stockpile.

    Science.gov (United States)

    Olszewski, Grzegorz; Boryło, Alicja; Skwarzec, Bogdan

    The aim of this study was to determine uranium concentrations in common nettle (Urtica dioica) plants and corresponding soils samples which were collected from the area of phosphogypsum stockpile in Wiślinka (northern Poland). The uranium concentrations in roots depended on its concentrations in soils. Calculated BCF and TF values showed that soils characteristics and air deposition affect uranium absorption and that different uranium species have different affinities to U. dioica plants. The values of (234)U/(238)U activity ratio indicate natural origin of these radioisotopes in analyzed plants. Uranium concentration in plants roots is negatively weakly correlated with distance from phosphogypsum stockpile.

  14. Determination of 238u/235u, 236u/238u and uranium concentration in urine using sf-icp-ms and mc-icp-ms: an interlaboratory comparison.

    Science.gov (United States)

    Parrish, Randall R; Thirlwall, Matthew F; Pickford, Chris; Horstwood, Matthew; Gerdes, Axel; Anderson, James; Coggon, David

    2006-02-01

    Accidental exposure to depleted or enriched uranium may occur in a variety of circumstances. There is a need to quantify such exposure, with the possibility that the testing may post-date exposure by months or years. Therefore, it is important to develop a very sensitive test to measure precisely the isotopic composition of uranium in urine at low levels of concentration. The results of an interlaboratory comparison using sector field (SF)-inductively coupled plasma-mass spectrometry (ICP-MS) and multiple collector (MC)-ICP-MS for the measurement of uranium concentration and U/U and U/U isotopic ratios of human urine samples are presented. Three urine samples were verified to contain uranium at 1-5 ng L and shown to have natural uranium isotopic composition. Portions of these urine batches were doped with depleted uranium (DU) containing small quantities of U, and the solutions were split into 100 mL and 400 mL aliquots that were subsequently measured blind by three laboratories. All methods investigated were able to measure accurately U/U with precisions of approximately 0.5% to approximately 4%, but only selected MC-ICP-MS methods were capable of consistently analyzing U/U to reasonable precision at the approximately 20 fg L level of U abundance. Isotope dilution using a U tracer demonstrates the ability to measure concentrations to better than +/-4% with the MC-ICP-MS method, though sample heterogeneity in urine samples was shown to be problematic in some cases. MC-ICP-MS outperformed SF-ICP-MS methods, as was expected. The MC-ICP-MS methodology described is capable of measuring to approximately 1% precision the U/U of any sample of human urine over the entire range of uranium abundance down to <1 ng L, and detecting very small amounts of DU contained therein.

  15. Bioaccumulation of polonium ({sup 210}Po) and uranium ({sup 234}U, {sup 238}U) in plants around phosphogypsum waste heap in Wislinka (northern Poland)

    Energy Technology Data Exchange (ETDEWEB)

    Borylo, A.; Skwarzec, B. [Gdansk Univ. (Poland). Faculty of Chemistry

    2011-07-01

    In the study the activities of polonium {sup 210}Po and uranium {sup 234}U, {sup 238}U in plants, collected near phosphogypsum waste heap in Wis'linka (northern Poland), were determined by using the alpha spectrometry. The obtained results revealed that the concentrations of {sup 210}Po, {sup 234}U, and {sup 238}U in the analyzed plants were differentiated. In the analyzed flora organisms the highest amounts of polonium and uranium were found in ruderal plant samples as well as willow samples (Salix viminalis) from protection zone of phosphogypsum waste heap. The concentrations of {sup 210}Po, {sup 234}U and {sup 238}U in the analyzed plants were higher in roots than in green parts of plants. The higher concentrations of {sup 210}Po and {sup 238}U radionuclides were estimated for hydrophyte (common sedge Carex nigra Reichard), the favourite habitat of which is particularly wet meadow and for plants collected in the vicinity of phosphogypsum waste heap. The major source of polonium and uranium in analyzed plants is root system. The values of {sup 234}U/ {sup 238}U activity ratio in all analyzed plants are closed to one, what indicated that source of uranium in analyzed plants is phosphogypsum. The highest uranium and polonium concentrations were characterized for plants, which are covered with tomentose. The comparability polonium and uranium contents were confirmed in edible plants, but higher accumulation was determined in ripe species than immature species of vegetables. The higher polonium and uranium concentrations were noticed in green parts of plant, the lower in roots. Polonium concentration in cultivated plants samples was not species diverse. Therefore, the significant source of polonium and uranium in analyzed plants is wet and dry atmospheric falls gathering the soil and air dust from phosphogypsum waste dump. The maximum {sup 210}Po and {sup 238}U radionuclides concentrations were found in green parts of red beet (Beta vulgaris esculenta), the

  16. Investigating Uranium Mobility Using Stable Isotope Partitioning of 238U/235U and a Reactive Transport Model

    Science.gov (United States)

    Bizjack, M.; Johnson, T. M.; Druhan, J. L.; Shiel, A. E.

    2015-12-01

    We report a numerical reactive transport model which explicitly incorporates the effectively stable isotopes of uranium (U) and the factors that influence their partitioning in bioactive systems. The model reproduces trends observed in U isotope ratios and concentration measurements from a field experiment, thereby improving interpretations of U isotope ratios as a tracer for U reactive transport. A major factor contributing to U storage and transport is its redox state, which is commonly influenced by the availability of organic carbon to support metal-reducing microbial communities. Both laboratory and field experiments have demonstrated that biogenic reduction of U(VI) fractionates the stable isotope ratio 238U/235U, producing an isotopically heavy solid U(IV) product. It has also been shown that other common reactive transport processes involving U do not fractionate isotopes to a consistently measurable level, which suggests the capacity to quantify the extent of bioreduction occurring in groundwater containing U using 238U/235U ratios. A recent study of a U bioremediation experiment at the Rifle IFRC site (Colorado, USA) applied Rayleigh distillation models to quantify U stable isotope fractionation observed during acetate amendment. The application of these simplified models were fit to the observations only by invoking a "memory-effect," or a constant source of low-concentration, unfractionated U(VI). In order to more accurately interpret the measured U isotope ratios, we present a multi-component reactive transport model using the CrunchTope software. This approach is capable of quantifying the cycling and partitioning of individual U isotopes through a realistic network of transport and reaction pathways including reduction, oxidation, and microbial growth. The model incorporates physical heterogeneity of the aquifer sediments through zones of decreased permeability, which replicate the observed bromide tracer, major ion chemistry, U concentration, and U

  17. Bioaccumulation of polonium (210Po, uranium (234U, 238U isotopes and trace metals in mosses from Sobieszewo Island, northern Poland

    Directory of Open Access Journals (Sweden)

    Boryło A.

    2013-04-01

    Full Text Available The objective of this study was determination of the polonium (210Po, uranium (234U and 238U radionuclides and trace metals (Pb, Fe, Zn, Cu, Ni, Cd, Hg concentrations in mosses samples from Sobieszewo Island near the phosphogypsum waste dump in Wiślinka (northern Poland. The obtained results revealed that the concentrations of 210Po, 234U, and 238U in the two analyzed kinds of mosses: Pleurozium schreberi and Dicranum scoparium were similar. Among the analyzed trace metals the highest concentration in mosses was recorded for iron, while the lowest for nickel, cadmium and mercury. The obtained studies showed that the sources of polonium and uranium isotopes, as well as trace metals in analyzed mosses are air city contaminations transported from Gdańsk and from existing in the vicinity the phosphogypsum waste heap in Wiślinka (near Gdańsk.

  18. Uranium ((234)U, (235)U and (238)U) contamination of the environment surrounding phosphogypsum waste heap in Wiślinka (northern Poland).

    Science.gov (United States)

    Olszewski, Grzegorz; Boryło, Alicja; Skwarzec, Bogdan

    2015-08-01

    The aim of this work was to determine the uranium concentration ((234)U, (235)U and (238)U) and values of the activity ratio (234)U/(238)U in soil samples collected near phosphogypsum waste heap in Wiślinka (northern Poland). On the basis of the studies it was found that the values of the (234)U/(238)U activity ratio in the analyzed soils collected in the vicinity of phosphogypsum dump in Wiślinka are in most cases close to one and indicate the phosphogypsum origin of the analyzed nuclides. The obtained results of uranium concentrations are however much lower than in previous years before closing of the phosphogypsum stockpile. After this process and covering the phosphogypsum stockpile in Wiślinka with sewage sludge, phosphogypsum particles are successfully immobilized. In the light of the results the use of phosphate fertilizers seems to be a major problem. Prolonged and heavy rains can cause leaching accumulated uranium isotopes in the phosphogypsum stockpile, which will be washed into the Martwa Wisła and on the fields in the immediate vicinity of this storage.

  19. 238U series isotopes and 232Th in carbonates and black shales from the Lesser Himalaya: implications to dissolved uranium abundances in Ganga-Indus source waters.

    Science.gov (United States)

    Singh, S K; Dalai, Tarun K; Krishnaswami, S

    2003-01-01

    238U and (232)Th concentrations and the extent of (238)U-(234)U-(230)Th radioactive equilibrium have been measured in a suite of Precambrian carbonates and black shales from the Lesser Himalaya. These measurements were made to determine their abundances in these deposits, their contributions to dissolved uranium budget of the headwaters of the Ganga and the Indus in the Himalaya and to assess the impact of weathering on (238)U-(234)U-(230)Th radioactive equilibrium in them. (238)U concentrations in Precambrian carbonates range from 0.06 to 2.07 microg g(-1). The 'mean' U/Ca in these carbonates is 2.9 ng U mg(-1) Ca. This ratio, coupled with the assumption that all Ca in the Ganga-Indus headwaters is of carbonate origin and that U and Ca behave conservatively in rivers after their release from carbonates, provides an upper limit on the U contribution from these carbonates, to be a few percent of dissolved uranium in rivers. There are, however, a few streams with low uranium concentrations, for which the carbonate contribution could be much higher. These results suggest that Precambrian carbonates make only minor contributions to the uranium budget of the Ganga-Indus headwaters in the Himalaya on a basin wide scale, however, they could be important for particular streams. Similar estimates of silicate contribution to uranium budget of these rivers using U/Na in silicates and Na* (Na corrected for cyclic and halite contributions) in river waters show that silicates can contribute significantly (approximately 40% on average) to their U balance. If, however, much of the uranium in these silicates is associated with weathering resistant minerals, then the estimated silicate uranium component would be upper limits. Uranium concentration in black shales averages about 37 microg g(-1). Based on this concentration, supply of U from at least approximately 50 mg of black shales per liter of river water is needed to balance the average river water U concentration, 1.7 microg L

  20. Non-destructive field measurement of the ratio /sup 235/U//sup 238/U in depleted to moderately enriched uranium

    Energy Technology Data Exchange (ETDEWEB)

    Balagna, J.P.; Cowan, G.A.

    1977-01-01

    The exploration of a natural reactor site is expedited by prompt measurement of /sup 235/U to /sup 238/U ratios near the mining operation. An instrument has been constructed which uses the relative fission rates of /sup 235/U and /sup 238/U in fast and moderated neutron spectra to measure the isotopic ratio. This device can be placed in the field and allows continuous monitoring of ore as a rich deposit of uranium is mined. With rapid return of isotopic information to the operator it is possible to locate a fossil reactor before it has been destroyed. The relative fast neutron and slow neutron fission rates induced in uranium which is depleted to moderately enriched in /sup 235/U may be used to measure the isotopic ratio /sup 235/U//sup 238/U quickly and nondestructively with a relative error of a few percent. When a neutron source such as /sup 252/Cf is used, the measurements may be made in the field.

  1. Activity ratios of (234)U/(238)U and (226)Ra/(228)Ra for transport mechanisms of elevated uranium in alluvial aquifers of groundwater in south-western (SW) Punjab, India.

    Science.gov (United States)

    Kumar, A; Karpe, R K; Rout, S; Gautam, Y P; Mishra, M K; Ravi, P M; Tripathi, R M

    2016-01-01

    The concentrations of total dissolved uranium (U), its isotopic composition ((234)U, (235)U, (238)U) and two long lived Ra isotopes ((226)Ra and (228)Ra) in alluvial aquifers of groundwater were determined to investigate the groundwater flow pattern in the south-western (SW) Punjab, India. Particular attention was given to the spatial variability of activity ratios (ARs) of (234)U/(238)U and (226)Ra/(228)Ra to predict the possible sources and supply process of U into the water from the solid phase. The measured groundwater (234)U/(238)U ARs were ∼1 or >1 in the shallow zone (depth  30 m) with relatively low U concentration. The simultaneous elevated U concentration and (234)U/(238)U ARs in waters were possibly due to differences in imprints of rock-water interactions under hydrologic conditions. However, (234)U/(238)U ARs aquifers.

  2. Recent measurements of 234U/238U isotope ratio in spring waters from the Hadzici area.

    Science.gov (United States)

    Vidic, Alfred; Ilić, Zorana; Benedik, Ljudmila

    2013-06-01

    The Hadzici area has become interesting for investigation since depleted uranium ammunition had been employed in 1995 during the NATO air strike campaign in Bosnia and Herzegovina. The purpose of this study is to determine uranium concentration and (234)U/(238)U activity ratio in the spring waters of this area and to investigate their relationship, as well as spatial variations. The spring water samples were taken at 18 sites in total. For the determination of uranium radioisotopes, radiochemical separation procedure followed by alpha-particle spectrometry was applied. Uranium concentration in analyzed waters range from 0.15 to 1.12 μg/L. Spring waters from carbonate based sediments have a lower uranium concentration of between 0.15 and 0.43 μg/L, in comparison to waters sampled within sandstone-based sediments ranging from 0.53 to 1.12 μg/L. Dissolved uranium shows significant spatial variability and correlation with bedrock type confirmed by Principal Component Analysis and Hierarchical Cluster Analysis. The majority of the analyzed waters have a (234)U/(238)U activity ratio ranging from 1.02 to 1.90, of which half of the results range between 1.02 and 1.16. No apparent depleted uranium (DU) contamination was observed, as (234)U/(238)U activity ratio is dependent on geochemical conditions in the environment. Even though the tested spring waters demonstrate significant variability in uranium concentration, (234)U/(238)U activity ratio and (234)U excess, waters with similar uranium isotopic signatures are observable within the region. The guidelines on the spatial redistribution of dissolved uranium (corresponding to (238)U mass concentration), along with (234)U/(238)U activity ratios were provided by the Inverse Distance Weighting (IDW) method. Waters having similar isotopic signature have been delineated.

  3. Field analyses of (238)U and (226)Ra in two uranium mill tailings piles from Niger using portable HPGe detector.

    Science.gov (United States)

    Déjeant, Adrien; Bourva, Ludovic; Sia, Radia; Galoisy, Laurence; Calas, Georges; Phrommavanh, Vannapha; Descostes, Michael

    2014-11-01

    The radioactivities of (238)U and (226)Ra in mill tailings from the U mines of COMINAK and SOMAÏR in Niger were measured and quantified using a portable High-Purity Germanium (HPGe) detector. The (238)U and (226)Ra activities were measured under field conditions on drilling cores with 600s measurements and without any sample preparation. Field results were compared with those obtained by Inductive Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) and emanometry techniques. This comparison indicates that gamma-ray absorption by such geological samples does not cause significant deviations. This work shows the feasibility of using portable HPGe detector in the field as a preliminary method to observe variations of radionuclides concentration with the aim of identifying samples of interest. The HPGe is particularly useful for samples with strong secular disequilibrium such as mill tailings.

  4. Ground water contamination with (238)U, (234)U, (235)U, (226)Ra and (210)Pb from past uranium mining: cove wash, Arizona.

    Science.gov (United States)

    Dias da Cunha, Kenya Moore; Henderson, Helenes; Thomson, Bruce M; Hecht, Adam A

    2014-06-01

    The objectives of the study are to present a critical review of the (238)U, (234)U, (235)U, (226)Ra and (210)Pb levels in water samples from the EPA studies (U.S. EPA in Abandoned uranium mines and the Navajo Nation: Red Valley chapter screening assessment report. Region 9 Superfund Program, San Francisco, 2004, Abandoned uranium mines and the Navajo Nation: Northern aum region screening assessment report. Region 9 Superfund Program, San Francisco, 2006, Health and environmental impacts of uranium contamination, 5-year plan. Region 9 Superfund Program, San Franciso, 2008) and the dose assessment for the population due to ingestion of water containing (238)U and (234)U. The water quality data were taken from Sect. "Data analysis" of the published report, titled Abandoned Uranium Mines Project Arizona, New Mexico, Utah-Navajo Lands 1994-2000, Project Atlas. Total uranium concentration was above the maximum concentration level for drinking water (7.410-1 Bq/L) in 19 % of the water samples, while (238)U and (234)U concentrations were above in 14 and 17 % of the water samples, respectively. (226)Ra and (210)Pb concentrations in water samples were in the range of 3.7 × 10(-1) to 5.55 × 102 Bq/L and 1.11 to 4.33 × 102 Bq/L, respectively. For only two samples, the (226)Ra concentrations exceeded the MCL for total Ra for drinking water (0.185 Bq/L). However, the (210)Pb/(226)Ra ratios varied from 0.11 to 47.00, and ratios above 1.00 were observed in 71 % of the samples. Secular equilibrium of the natural uranium series was not observed in the data record for most of the water samples. Moreover, the (235)U/(total)U mass ratios ranged from 0.06 to 5.9 %, and the natural mass ratio of (235)U to (total)U (0.72 %) was observed in only 16 % of the water samples, ratios above or below the natural ratio could not be explained based on data reported by U.S. EPA. In addition, statistical evaluations showed no correlations among the distribution of the radionuclide concentrations

  5. Gamma-ray spectrometer measurement of 238U/235U in uranium ore from a natural reactor at Oklo, Gabon

    Science.gov (United States)

    Moxham, Robert M.

    1976-01-01

    About 20 years ago, Kuroda theorized that a high-grade uranium deposit emplaced about 2x109 years ago could achieve criticality and sustain a nuclear chain reaction, given a sufficient thickness of high-grade ore and an appropriate water content. Such a natural reactor was found in 1972 at the Oklo deposit, Gabon. The ore contains as much as 60 percent uranium, but the isotopic abundance of 235U is as little as 0.4 percent in contrast to the normal abundance of 0.7110 percent 235U. A sample from the Oklo deposit containing about 0.51 atom percent 235U (by mass spectrometer) was analyzed by a gamma-ray spectrometer system, using a high-purity planar germanium detector. The 235U was determined from its daughter's (234Th) 63.3 keV photopeak; the 235U was determined from its 143.8 and 163.4 keV photopeaks. The ratios of these photopeaks were compared with that from a standard having normal uranium isotopic content; the resulting calculations give a 235U abundance of 0.54 atom percent in the Oklo sample. The gamma-ray spectrum also contains lines from five other isotopes in the uranium series, which indicate the Oklo sample to be at or near secular equilibrium, as the time elapsed since the nuclear reaction ended was sufficient to permit the daughters to achieve equilibrium.

  6. 贫化铀球装置内的238U(n,2n)反应率实验研究%Measurement of 238 U(n,2n) Reaction Rate in Depleted Uranium Sphere

    Institute of Scientific and Technical Information of China (English)

    朱传新; 牟云峰; 郑普; 王新华; 郭海萍; 何铁

    2015-01-01

    采用两套不同尺寸的贫化铀球装置开展了装置内部的238 U (n ,2n)反应率实验研究,利用PD‐300加速器D‐T中子源辐照实验装置,源强变化采用伴随粒子法监测,238 U圆片放置在实验装置的45°孔道内,分布在距中子源不同距离处,辐照结束后,采用 HPGe探测器测量238 U圆片活化γ射线。实验结果与蒙特卡罗程序模拟计算结果进行了比较和分析。结果表明,238 U (n ,2n)反应率实验结果与模拟计算值较吻合,238 U (n ,2n)反应率随球体半径 r的增加,近似服从e- ar/r2分布规律。%The 238 U (n ,2n) reaction rates of two depleted uranium spheres were meas‐ured .The depleted uranium spheres were irradiated by D‐T neutron at PD‐300 accelera‐tor .The intensity of neutron source was monitored by the associated‐alpha particles from the T (d ,n)He reaction .After radiation ,the activated gamma rays of uranium foils in the 45° hole of uranium spheres were measured using HPGe detector .The 238 U(n ,2n) reaction rates of two depleted uranium spheres were calculated using Monte‐Carlo simu‐lation .It shows that the 238 U(n ,2n) reaction rates from experiments are agreed with the calculations .The change of 238 U(n ,2n) reaction rate with the radius r of depleted urani‐um sphere is obeyed approximately the distribution of e - ar/r2 .

  7. 234U/238U Disequilibrium along stylolitic discontinuities in deep Mesozoic limestone formations of the Eastern Paris basin: evidence for discrete uranium mobility over the last 1–2 million years

    Directory of Open Access Journals (Sweden)

    P. Deschamps

    2004-01-01

    Full Text Available The (234U/238 equilibrium state of borehole core samples from the deep, low-permeability limestone formations surrounding the target argilite layer of the Meuse/Haute-Marne experimental site of the French agency for nuclear waste management -ANDRA- (Agence nationale pour la gestion des déchets radioactifs was examined to improve understanding of naturally occurring radionuclide behaviour in such geological settings. Highly precise, accurate MC-ICP-MS measurements of the (234U/238U activity ratio show that limestone samples characterised by pressure dissolution structures (stylolites or dissolution seams display systematic (234U/238U disequilibria, while the pristine carbonate samples remain in the secular equilibrium state. The systematic feature is observed throughout the zones marked by pressure dissolution structures: (i the material within the seams shows a deficit of 234U over 238U ((234U/238U down to 0.80 and (ii the surrounding carbonate matrix is characterised by an activity ratio greater than unity (up to 1.05. These results highlight a centimetric-scale uranium remobilisation in the limestone formations along these sub-horizontal seams. Although their nature and modalities are not fully understood, the driving processes responsible for these disequilibria were active during the last 1–2 Ma. Keywords: uranium isotopes, multiple-collector ICP-MS, waste management, remobilisation, migration

  8. 234U/238U Disequilibrium along stylolitic discontinuities in deep Mesozoic limestone formations of the Eastern Paris basin: evidence for discrete uranium mobility over the last 1-2 million years

    Science.gov (United States)

    Deschamps, P.; Hillaire-Marcel, C. E.; Michelot, J.-L.; Doucelance, R.; Ghaleb, B.; Buschaert, S.

    The (234U/238) equilibrium state of borehole core samples from the deep, low-permeability limestone formations surrounding the target argilite layer of the Meuse/Haute-Marne experimental site of the French agency for nuclear waste management -ANDRA- (Agence nationale pour la gestion des déchets radioactifs) was examined to improve understanding of naturally occurring radionuclide behaviour in such geological settings. Highly precise, accurate MC-ICP-MS measurements of the (234U/238U) activity ratio show that limestone samples characterised by pressure dissolution structures (stylolites or dissolution seams) display systematic (234U/238U) disequilibria, while the pristine carbonate samples remain in the secular equilibrium state. The systematic feature is observed throughout the zones marked by pressure dissolution structures: (i) the material within the seams shows a deficit of 234U over 238U ((234U/238U) down to 0.80) and (ii) the surrounding carbonate matrix is characterised by an activity ratio greater than unity (up to 1.05). These results highlight a centimetric-scale uranium remobilisation in the limestone formations along these sub-horizontal seams. Although their nature and modalities are not fully understood, the driving processes responsible for these disequilibria were active during the last 1-2 Ma.

  9. Uranium isotopic ratio measurements ({sup 235}U/{sup 238}U) by laser ablation high resolution inductively coupled plasma mass spectrometry for environmental radioactivity monitoring - {sup 235}U/{sup 238}U isotope ratio analysis by LA-ICP-MS-HR for environmental radioactivity monitoring

    Energy Technology Data Exchange (ETDEWEB)

    David, K.; Mokili, M.B.; Rousseau, G.; Deniau, I.; Landesman, C. [SUBATECH, Ecole des Mines de Nantes, Universite de Nantes, CNRS/IN2P3, 4 rue Alfred Kastler, 44307 Nantes cedex 3 (France)

    2014-07-01

    The protection of the aquatic and terrestrial environments from a broad range of contaminants spread by nuclear activities (nuclear plants, weapon tests or mining) require continuous monitoring of long-lives radionuclides that were released into the environment. The precise determination of uranium isotope ratios in both natural and potential contaminated samples is of primary concern for the nuclear safeguards and the control of environmental contamination. As an example, analysis of environmental samples around nuclear plants are carried out to detect the traces in the environment originating from nuclear technology activities. This study deals with the direct analysis of {sup 235}U/{sup 238}U isotope ratios in real environmental solid samples performed with laser ablation (LA)-HR-ICP-MS. A similar technique has already been reported for the analysis of biological samples or uranium oxide particles [1,2] but to our knowledge, this was never applied on real environmental samples. The high sensitivity, rapid acquisition time and low detection limits are the main advantages of high resolution ICP-MS for accurate and precise isotope ratio measurements of uranium at trace and ultra-trace levels. In addition, the use of laser ablation allows the analysis of solid samples with minimal preparation. A a consequence, this technique is very attractive for conducting rapid direct {sup 235}U/{sup 238}U isotope ratio analysis on a large set of various matrix samples likely to be encountered in environmental monitoring such as corals, soils, sands, sediments, terrestrial and marine bio-indicators. For the present study, LA-ICP-MS-HR analyses are performed using a New Wave UP213 nano-second Nd:YAG laser coupled to a Thermo Element-XR high resolution mass spectrometer. Powdered samples are compacted with an hydraulic press (5 tons) in order to obtain disk-shaped pellet (10-13 mm in diameter and 2 mm in thickness). The NIST612 reference glass is used for LA-ICP-MS-HR tuning and as

  10. Nondestructive determination of the 238U content in mental uranium sample by using the activation method%用活化法无损测定金属铀样品中238U的含量

    Institute of Scientific and Technical Information of China (English)

    汪超; 肖军; 王攀; 李映映; 李子越; 罗小兵

    2016-01-01

    238U 作为一种重要的裂变材料,其含量的准确测定在裂变产额数据测量中具有重要意义。在四川大学2.5 MeV质子静电加速器上,利用T(p,n)3He反应产生的483 keV单能中子照射金属铀样品,对照射后生成放射性核素239Np的特征γ射线进行测量,利用已知的238U(n,γ)俘获截面数据实现了对238U含量的准确测量。对影响测量结果准确性的因素做了细致分析,采用蒙特卡罗方法应用软件 MCNPX (Monte Carlo N-Particle eXtended)对中子的多次散射效应和中子注量衰减效应进行了修正,对γ射线在样品中的自吸收也进行了修正,修正后的实验结果是2.8842 g金属铀含5.7128×1021个238U原子,实验结果的不确定度是4.1%。%Background: As a kind of important fission material, the accurate quantification of 238U is of great significance in the measurement of fission yield data. Purpose:The aim is to nondestructively measure the content of 238U by using the activation method. Methods:Neutron of 483-keV produced by the reaction of T(p,n)3He induces 238U occurring radiative capture reaction on the 2.5-MeV electrostatic accelerator of Sichuan University. The atomic number of 238U in uranium samples is measured by using 278-keV gamma ray of 239Np on the detector of high purity germanium (HPGe) and the data of capture cross section. Results: The deflections which were caused by multiple scattering and self-shielding of the target and sample in the experiment were corrected with MCNPX (Monte Carlo N-Particle eXtended). The result of the experiment is that the atomic number of 238U in the 2.884 2-g metal uranium is 5.712 8×1021. Conclusion:The uncertainty of the experimental result is 4.1%. We can reduce the effect of multiple scattering effects and self-shielding by decreasing the thickness of the bottom lining, target tube, water layer and cladding material of the sample.

  11. Accurate fast method with high chemical yield for determination of uranium isotopes ({sup 234}U, {sup 235}U, {sup 238}U) in granitic samples using alpha spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Guirguis, Laila A., E-mail: lailagurgus@yahoo.com; Farag, Nagdy M.; Salim, Adham K.

    2015-03-21

    The present study aims to use the α-spectroscopy at Nuclear Materials Authority (NMA) of Egypt. A radiochemical technique for analysis uranium isotopes was carried out for ten mineralized granitic samples together with the International standards RGU-1 (IAEA) and St{sub 4} (NMA). Several steps of sample preparation, radiochemical separation and source preparation were performed before analysis. Uranium was separated from sample matrix with 0.2 M TOPO in cyclohexane as an extracting agent with a chemical yield 98.95% then uranium was purified from lanthanides and actinides present with 0.2 M TOA in xylene as an extracting agent. The pure fraction was electrodeposited on a mirror-polished copper disc from buffer solution (NaHSO{sub 4}+H{sub 2}SO{sub 4}+NH{sub 4}OH). Rectangle pt-electrode with an anode-cathode distance of 2 cm was used. Current was 900 mA and the electrodeposition time reach up to 120 min. The achieved results show that the chemical yield ranged between 87.9±6.8 and 98±8.6. - Highlights: • Radiochemical technique for analysis uranium isotopes. • Alpha-particle spectrometry is performed after a radiochemical procedure. • Electrodeposition conditions for preparation of alpha uranium source. • Using {sup 232}U (t{sub 1/2}=70.6a, E{sub α}=5320.24 keV, intensity=69.1%) as an internal tracer makes it a highly reliable technique.

  12. Accurate fast method with high chemical yield for determination of uranium isotopes (234U, 235U, 238U) in granitic samples using alpha spectroscopy

    Science.gov (United States)

    Guirguis, Laila A.; Farag, Nagdy M.; Salim, Adham K.

    2015-03-01

    The present study aims to use the α-spectroscopy at Nuclear Materials Authority (NMA) of Egypt. A radiochemical technique for analysis uranium isotopes was carried out for ten mineralized granitic samples together with the International standards RGU-1 (IAEA) and St4 (NMA). Several steps of sample preparation, radiochemical separation and source preparation were performed before analysis. Uranium was separated from sample matrix with 0.2 M TOPO in cyclohexane as an extracting agent with a chemical yield 98.95% then uranium was purified from lanthanides and actinides present with 0.2 M TOA in xylene as an extracting agent. The pure fraction was electrodeposited on a mirror-polished copper disc from buffer solution (NaHSO4+H2SO4+NH4OH). Rectangle pt-electrode with an anode-cathode distance of 2 cm was used. Current was 900 mA and the electrodeposition time reach up to 120 min. The achieved results show that the chemical yield ranged between 87.9±6.8 and 98±8.6.

  13. Accumulation of polonium 210Po, uranium (234U and 238U and plutonium (238Pu and 239+240Pu in tissues and organs of deer Carvidae from northern Poland

    Directory of Open Access Journals (Sweden)

    Strumińska-Parulska D. I.

    2013-04-01

    Full Text Available Livers, kidneys and muscles of large herbivorous animals: roe deer (Capreolus capreolus, red deer (Cervus elaphus and fallow deer (Dama dama, collected in northern Poland, were the subject of the investigation. Polonium, uranium and plutonium activities were measured using alpha spectrometry along with relevant radiochemical procedures. The average concentrations of 210Po ranged between 0.02±0.01 Bq kg−1 ww in muscles and 7.15±0.12 Bq kg−1 ww in kidneys. The concentration of 238U ranged widely between 2.49±0.18 and 69.37±5.45 mBq kg−1 ww. The average concentrations of 239+240Pu ranged between 0.18±0.04 mBq kg−1 ww in muscle and 2.77±0.60 mBq kg−1 ww in kidneys. Statistical analysis showed that the sampling location, sex, age and species did not influence on the radioisotope activities in the analyzed samples.

  14. Origin and geochemical behavior of uranium in marine sediments. Utilization of the {sup 234}U/{sup 238}U ratio in marine geochemistry; Origine et comportement geochimique de l`uranium dans les sediments marins. Utilisation du rapport ({sup 234}U/{sup 238}U) en geochimie marine

    Energy Technology Data Exchange (ETDEWEB)

    Organo, Catherine [Paris-11 Univ., 91 - Orsay (France)

    1997-01-20

    The first part of this thesis presents the current situation of knowledge of uranium in marine environment. The second part describes the methods of analysis as well as the material support of the study, i.e., the sediments and marine deposits investigated. The third part is dedicated to the study of uranium mobility in marine sediments characterized by detrital terrigenous composition (pelagic clays). This approach allowed quantifying the entering and leaving flux of uranium after the sediment settling and, to discuss, on this basis, the consequences on the uranium oceanic balance. In the third part the origin and behavior of uranium in zones of high surface productivity is studied. The uranium enrichments observed in the hemi-pelagic sediments of the EUMELI (J.G.O.F.S.-France) programme will constitute a material of study adequate for measuring the variations in the {sup 234}U/2{sup 38U} ratio in solid phase, in response to the oxido-reducing characteristics of the sediment. Thus establishing the origin of the trapped uranium has been possible. Also, the nature of the sedimentary phases related to uranium in bio-genetic sediments in the Austral Ocean was determined. Thus a relationship between the variations in the {sup 234}U/{sup 238} and the diagenetic transformations was possible to establish. Finally in the fifth part a study of the behavior of uranium in a polymetallic shell characteristic for deposits of hydrogenized origin 146 refs., 57 figs., 23 tabs.

  15. Experimental Determination of the Antineutrino Spectrum of the Fission Products of $^{238}$U

    CERN Document Server

    Haag, N; Hofmann, M; Oberauer, L; Potzel, W; Schreckenbach, K; Wagner, F M

    2013-01-01

    An experiment was performed at the scientific neutron source FRM II in Garching to determine the cumulative antineutrino spectrum of the fission products of $^{238}$U. This was achieved by irradiating target foils of natural uranium with a thermal and a fast neutron beam and recording the emitted $\\beta$-spectra with a gamma-suppressing electron-telescope. The obtained $\\beta$-spectrum of the fission products of $^{235}$U was normalized to the data of the magnetic spectrometer BILL of $^{235}$U. This method strongly reduces systematic errors in the $^{238}$U measurement. The $\\beta$-spectrum of $^{238}$U was converted into the corresponding antineutrino spectrum. The final $\\bar\

  16. Ocean mixing and ice-sheet control of seawater 234U/238U during the last deglaciation

    Science.gov (United States)

    Chen, Tianyu; Robinson, Laura F.; Beasley, Matthew P.; Claxton, Louis M.; Andersen, Morten B.; Gregoire, Lauren J.; Wadham, Jemma; Fornari, Daniel J.; Harpp, Karen S.

    2016-11-01

    Seawater 234U/238U provides global-scale information about continental weathering and is vital for marine uranium-series geochronology. Existing evidence supports an increase in 234U/238U since the last glacial period, but the timing and amplitude of its variability has been poorly constrained. Here we report two seawater 234U/238U records based on well-preserved deep-sea corals from the low-latitude Atlantic and Pacific Oceans. The Atlantic 234U/238U started to increase before major sea-level rise and overshot the modern value by 3 per mil during the early deglaciation. Deglacial 234U/238U in the Pacific converged with that in the Atlantic after the abrupt resumption of Atlantic meridional overturning. We suggest that ocean mixing and early deglacial release of excess 234U from enhanced subglacial melting of the Northern Hemisphere ice sheets have driven the observed 234U/238U evolution.

  17. The inflow of 234U and 238U from the River Odra drainage basin to the Baltic Sea

    Directory of Open Access Journals (Sweden)

    Bogdan Skwarzec

    2010-12-01

    Full Text Available In this study the activity of uranium isotopes 234U and 238U in Odra river water samples, collected from October 2003 to July2004, was measured using alpha spectrometry. The uranium concentrations were different in each of the seasons analysed; the lowest values were recorded in summer. In all seasons, uranium concentrations were the highest in Bystrzyca river waters (from 27.81 ± 0.29Bq m-3 of 234U and 17.82 ± 0.23 Bq m-3 of 238U in spring to 194.76 ± 3.43 Bq m-3 of 234U and 134.88 ± 2.85 Bq m-3 of 238U in summer. The lowest concentrations were noted in the Mała Panew (from 1.33 ± 0.02 Bq m-3 of 234U and 1.06 ± 0.02 Bq m-3 of 238U in spring to 3.52 ± 0.05 Bq m-3 of 234U and 2.59± 0.04 Bq m-3 of 238U in autumn. The uranium radionuclides 234U and 238U in the water samples were not in radioactive equilibrium. The 234U / 238U activity ratios were the highest in Odra water samples collected at Głogów (1.84 in autumn, and the lowest in water from the Noteć (1.03 in winter and spring. The 234U / 238U activity ratio decreases along the main stream of the Odra, owing to changes in the salinity of the river's waters. Annually, 8.19 tons of uranium (126.29 G Bq of 234U and 100.80 G Bq of 238U flow into the Szczecin Lagoon with Odra river waters.

  18. Phosphate fertilizer influence on {sup 238} U content in vegetables

    Energy Technology Data Exchange (ETDEWEB)

    Lauria D, C.; Rodrigues S, J.I. [Instituto de Radioprotecao e Dosimetria (IRD/CNEN), Av. Salvador Allende s/n, Rio de Janeiro-RJ (Brazil); Ribeiro, F.C.A. [Centro Regional de Ciencias Nucleares (CRCN/CNEN) Av. Prof. Luiz Freire 200 Cidade Universitaria Recife-PE (Brazil)]. e-mail: dejanira@ird.gov.br

    2006-07-01

    Uranium is a naturally radioactive element, which is usually found in soils, superficial and ground water, vegetables and animals. After ingestion by human beings, most is excreted in few days by feces and urine, without reaching the bloodstream. However, a small part circulates through the body, being accumulated in the soft tissues, as kidneys. A minor fraction can remain in bones per some years, being able through the radioactive decay to irradiate adjacent tissues. Phosphate fertilizers used in conventional crop management can present variable amounts of uranium. In accordance with origin and use, the fertilizer can raise the content of this element in vegetables, and consequently to increase the human exposure for radiation due the consumption of vegetables. It is estimated that the use of phosphate fertilizer has at least doubled the prolonged exposure of humans from ingestion of food. This work aims to evaluate the contribution of organic and chemical fertilizer on the concentration of {sup 238} U in vegetable samples. An experiment with black beans (a very important vegetable for Brazilian people) was conducted in a field which soil has never been fertilized with any sort of fertilizer, located near to the Rio de Janeiro city. On the organic management, bovine manure was used, while on conventional management urea, potassium chloride and superphosphate were used. Simultaneously, black bean samples from not fertilized management were collected. In addition, lettuce and carrot samples from organic and conventional managements were collected in Nova Friburgo farms (the most important vegetable supplier of Rio de Janeiro city market). The analyses of {sup 238} U have been carried out by conventional fluorimetric method. The geometric mean of {sup 238} U concentrations in the carrot and lettuce samples from conventional management were similar with those from organic management, while for beans the conventional samples had higher values than those ones found in

  19. The production of unknown neutron-rich isotopes in $^{238}$U+$^{238}$U collisions at near-barrier energy

    CERN Document Server

    Zhao, Kai; Zhang, Yingxun; Wang, Ning; Li, Qingfeng; Shen, Caiwan; Wang, Yongjia; Wu, Xizhen

    2016-01-01

    The production cross sections for primary and residual fragments with charge number from $Z$=70 to 120 produced in the collision of $^{238}$U+$^{238}$U at 7.0 MeV/nucleon are calculated by the improved quantum molecular dynamics (ImQMD) model incorporated with the statistical evaporation model (HIVAP code). The calculation results predict that about sixty unknown neutron-rich isotopes from element Ra ($Z$=88) to Db ($Z$=105) can be produced with the production cross sections above the lower bound of $10^{-8}$ mb in this reaction. And almost all of unknown neutron-rich isotopes are emitted at the laboratory angles $\\theta_{lab}\\leq$ 60$^\\circ$. Two cases, i.e. the production of the unknown uranium isotopes with $A\\geq$ 244 and that of rutherfordium with $A\\geq$ 269 are investigated for understanding the production mechanism of unknown neutron-rich isotopes. It is found that for the former case the collision time between two uranium nuclei is shorter and the primary fragments producing the residues have smaller...

  20. Neutrons production in thick targets of Be and {sup 238}U bombarded by 100 MeV/u deuterons and in a thick target of C bombarded by 95 MeV/u {sup 36}Ar. Attenuation in concrete and dose equivalent rate of the activated uranium; Neutrons produits dans des cibles epaisses de Be et {sup 238}U irradiees par des deutons de 100 MeV/u et dans une cible epaisse de C irradiee par des {sup 36}Ar de 95 MeV/u. Longueurs d'attenuation dans du beton et debit d'equivalent de dose resultant de l'activation de l'uranium

    Energy Technology Data Exchange (ETDEWEB)

    Pauwels, N.; Proust, J.; Clapier, F.; Gara, P.; Obert, J. [Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire; Mirea, M. [Institute of Physics and Nuclear Engineering, Bucharest (Romania); Belier, G.; Ethvignot, T.; Granier, T. [CEA/DAM-Ile de France, 91 - Bruyeres-Le-Chatel (France). Service de Physique Nucleaire; Liang, C.F. [Paris-11 Univ., 91 - Orsay (France). Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse; Bajard, M.; Leroy, R.; Villari, A.C.C. [Grand Accelerateur National d' Ions Lourds (GANIL), 14 - Caen (France)

    1999-09-01

    Neutrons production in thick targets of Be and {sup 238}U bombarded by 100 MeV/u deuterons and in a thick target of C bombarded by 95 MeV/u {sup 36}Ar. Attenuation in concrete and dose equivalent rate of the activated uranium. The yields of secondary neutrons produced by the interaction of a beam with thick target were determined with activation detectors. Three projectile-target couples have been studied: deuterons (100 MeV/u)+{sup 238}U, deuterons (100 MeV/u)+{sup 9}Be and {sup 36}Ar (95 MeV/u)+{sup 12}C. At 0 deg.. the yields were also measured after a piece of concrete and the corresponding attenuation length evaluated. The dose rate of the uranium target was monitored during several days after the end of the irradiation. (author)

  1. Neutron Induced Capture and Fission Processes on 238U

    Directory of Open Access Journals (Sweden)

    Oprea Cristiana

    2016-01-01

    Full Text Available Nuclear data on Uranium isotopes are of crucial interest for new generation of nuclear reactors. Processes of interest are the nuclear reactions induced by neutrons and in this work mainly the capture and the fission process on 238U will be analyzed in a wide energy interval. For slow and resonant neutrons the many levels Breit – Wigner formalism is necessary. In the case of fast and very fast neutrons up to 200 MeV the nuclear reaction mechanism implemented in Talys will be used. The present evaluations are necessary in order to obtain the field of neutrons in the design of nuclear reactors and they are compared with experimental data from literature obtained from capture and (n,xn processes.

  2. Study on the formation of the composite system of 238U+238U

    Institute of Scientific and Technical Information of China (English)

    WU Xi-Zhen; TIAN Jun-Long; ZHAO Kai; ZHANG Ying-Xun; LI Zhu-Xia

    2009-01-01

    Strongly damped reactions of 238U+238U, at Ecm = 680-1880 MeV have been studied based on the improved quantum molecular dynamics model. We find that at a certain energy region the entrance channel potential is weakly repulsive and the dissipation is very strong after touching configuration, these two effects make the time delay of re-separation for colliding system. The single particle potential well of the transiently formed composite system has Coulomb barrier about 15-20 MeV high at the surface, which makes the excited unbound protons being still embedded in the potential well and moving in a common mono-single particle potential for a period of time and thus restrains from quick decay of the composite system.

  3. Determination of sup 238 U in marine organisms by inductively coupled plasma mass spectrometry. Yudo ketsugo plasma shitsuryo bunsekiho ni yoru kaiyo seibutsuchu no sup 238 U no teiryo

    Energy Technology Data Exchange (ETDEWEB)

    Ishii, T.; Nakahara, M; Matsuda, M.; Ishikawa, M. (National Institute of Radiological Sciences, Ibaraki (Japan))

    1991-05-25

    Since the {sup 238} U concentration in seawater is about 3ng/ml at the element level and the activity concentration is 40 {mu} Bq/ml which are considerably higher that those of other {alpha} radioactive materials, it is necessary to study the concentration levels of many marine organisms. After confirming that the inductively coupled plasma mass spectrometry as a new high sensitive analysis for multi-elements is effective to analyze heavy elements such as rare earth elements or uranium, etc., this method was applied to determine {sup 238} U in 55 species of marine organism. The {sup 238} U concentration in soft tissues of marine animal ranged from 0.076 to 5000ng/g wet weight and large difference of concentration was observed depending on the kind of animal and the tissue. Especially, the branchial heart of cephalopod molluscs showed the specific accumulation of {sup 238} U. The concentration factor of branchial heart of Octopus vulgaris which showed the highest value was calculated to be about 10 {sup 3} by comparing it with the concentration of {sup 238} U in Japanese coastal waterseas. The concentration of {sup 238} U in 20 species of algae ranged from 10 to 3700ng/g dry weight. 11 refs., 2 figs., 9 tabs.

  4. Electron scattering from the octupole band in /sup 238/U

    Energy Technology Data Exchange (ETDEWEB)

    Hirsch, A.; Creswell, C.; Bertozzi, W.; Heisenberg, J.; Hynes, M.V.; Kowalski, S.; Miska, H.; Norum, B.; Rad, F.N.; Sargent, C.P.; Sasanuma, T.; Turchinetz, W.

    1978-03-06

    A simple model for nuclear surface vibrations in permanently deformed nuclei does well in reproducing electron scattering cross sections of rotational levels built on a K/sup ..pi../= 0/sup -/ intrinsic octupole vibration in /sup 238/U.

  5. 238U/235U variations in meteorites: extant 247Cm and implications for Pb-Pb dating.

    Science.gov (United States)

    Brennecka, G A; Weyer, S; Wadhwa, M; Janney, P E; Zipfel, J; Anbar, A D

    2010-01-22

    The 238U/235U isotope ratio has long been considered invariant in meteoritic materials (equal to 137.88). This assumption is a cornerstone of the high-precision lead-lead dates that define the absolute age of the solar system. Calcium-aluminum-rich inclusions (CAIs) of the Allende meteorite display variable 238U/235U ratios, ranging between 137.409 +/- 0.039 and 137.885 +/- 0.009. This range implies substantial uncertainties in the ages that were previously determined by lead-lead dating of CAIs, which may be overestimated by several million years. The correlation of uranium isotope ratios with proxies for curium/uranium (that is, thorium/uranium and neodymium/uranium) provides strong evidence that the observed variations of 238U/235U in CAIs were produced by the decay of extant curium-247 to uranium-235 in the early solar system, with an initial 247Cm/235U ratio of approximately 1.1 x 10(-4) to 2.4 x 10(-4).

  6. Influence of soil structure on the "Fv approach" applied to (238)U and (226)Ra.

    Science.gov (United States)

    Blanco Rodríguez, P; Vera Tomé, F; Lozano, J C

    2017-02-01

    The soil-to-plant transfer factors were determined in a granitic area for the two long-lived uranium series radionuclides (238)U and (226)Ra. With the aim to identify a physical fraction of soil whose concentration correlates linearly with the plant concentration, the soil compartment was analyzed in various stages. An initial study identified the soil compartments as being either bulk soil or its labile fraction. The bulk soil was subsequently divided into three granulometric fractions consisting of: coarse sand, fine sand, and silt and clay. The soil-to-plant transfer of radionuclides for each of these three texture fractions was analyzed. Lastly, the labile fraction was extracted from each textural part, and the activity concentration of the radionuclides (238)U and (226)Ra was measured. In order to assess the influence of soil texture on the soil-to-plant transfer process, we sought to identify possible correlations between the activity concentration in the plant compartment and those found in the different fractions within each soil compartment. The results showed that the soil-to-plant transfer process for uranium and radium depends on soil grain size, where the results for uranium showed a linear relationship between the activity concentration of uranium in the plant and the fine soil fraction. In contrast, a linear relation between the activity concentration of radium in the plant and the soil coarse-sand fraction was observed. Additionally, the presence of phosphate and calcium in the soil of all of the compartments studied affected the soil-to-plant transfer of uranium and radium, respectively.

  7. (238)U and total radioactivity in drinking waters in Van province, Turkey.

    Science.gov (United States)

    Selçuk Zorer, Özlem; Dağ, Beşir

    2014-06-01

    As part of the national survey to evaluate natural radioactivity in the environment, concentration levels of total radioactivity and natural uranium have been analysed in drinking water samples. A survey to study natural radioactivity in drinking waters was carried out in the Van province, East Turkey. Twenty-three samples of drinking water were collected in the Van province and analysed for total α, total β and (238)U activity. The total α and total β activities were counted by using the α/β counter of the multi-detector low background system (PIC MPC-9604), and the (238)U concentrations were determined by inductively coupled plasma-mass spectrometry (Thermo Scientific Element 2). The samples were categorised according to origin: tap, spring or mineral supply. The activity concentrations for total α were found to range from 0.002 to 0.030 Bq L(-1) and for total β from 0.023 to 1.351 Bq L(-1). Uranium concentrations ranging from 0.562 to 14.710 μg L(-1) were observed in drinking waters. Following the World Health Organisation rules, all investigated waters can be used as drinking water.

  8. Annual committed effective dose from olive oil (due to 238U, 232Th, and 222Rn) estimated for members of the Moroccan public from ingestion and skin application.

    Science.gov (United States)

    Misdaq, M A; Touti, R

    2012-03-01

    Olive oil is traditionally refined and widely consumed by Moroccan rural populations. Uranium (238U), thorium (232Th), radon (222Rn), and thoron (220Rn) contents were measured in various locally produced olive oil samples collected in rural areas of Morocco. These radionuclides were also measured inside various bottled virgin olive oils consumed by the Moroccan populations. CR-39 and LR-115 type II solid state nuclear track detectors (SSNTDs) were used. Annual committed effective doses due to 238U, 232Th, and 222Rn from the ingestion of olive oil by the members of the general public were determined. The maximum total committed effective dose due to 238U, 232Th, and 222Rn from the ingestion of olive oil by adult members of Moroccan rural populations was found equal to 5.9 µSv y-1. The influence of pollution due to building material dusts and phosphates on the radiation dose to workers from the ingestion of olive oil was investigated, and it was found that the maximum total committed effective dose due to 238U, 232Th, and 222Rn was on the order of 0.22 mSy y-1. Committed effective doses to skin due to 238U, 232Th, and 222Rn from the application of olive oil masks by rural women were evaluated. The maximum total committed effective dose to skin due to 238U, 232Th, and 222Rn was found equal to 0.07 mSy y-1 cm-2.

  9. Uranium Isotope Ratios in Modern and Precambrian Soils

    Science.gov (United States)

    DeCorte, B.; Planavsky, N.; Wang, X.; Auerbach, D. J.; Knudsen, A. C.

    2015-12-01

    Uranium isotopes (δ238U values) are an emerging paleoredox proxy that can help to better understand the redox evolution of Earth's surface environment. Recently, uranium isotopes have been used to reconstruct ocean and atmospheric redox conditions (Montoya-Pino et al., 2010; Brennecka et al., 2011; Kendall et al., 2013; Dahl et al., 2014). However, to date, there have not been studies on paleosols, despite that paleosols are, arguably better suited to directly tracking the redox conditions of the atmosphere. Sedimentary δ238U variability requires the formation of the soluble, oxidized form of U, U(VI). The formation of U(VI) is generally thought to require oxygen levels orders of magnitude higher than prebiotic levels. Without significant U mobility, it would have been impossible to develop isotopically distinct pools of uranium in ancient Earth environments. Conversely, an active U redox cycle leads to significant variability in δ238U values. Here we present a temporally and geographically expansive uranium isotope record from paleosols and modern soils to better constrain atmospheric oxygen levels during the Precambrian. Preliminary U isotope measurements of paleosols are unfractionated (relative to igneous rocks), possibly because of limited fractionation during oxidation (e.g., {Wang, 2015 #478}) or insufficient atmospheric oxygen levels to oxidize U(IV)-bearing minerals in the bedrock. Further U isotope measurements of paleosols with comparison to modern soils will resolve this issue.

  10. 234U/238U isotope data from groundwater and solid-phase leachate samples near Tuba City Open Dump, Tuba City, Arizona

    Science.gov (United States)

    Johnson, Raymond H.; Horton, Robert J.; Otton, James K.; Ketterer, Michael K.

    2012-01-01

    This report releases 234U/238U isotope data, expressed as activity ratios, and uranium concentration data from analyses completed at Northern Arizona University for groundwater and solid-phase leachate samples that were collected in and around Tuba City Open Dump, Tuba City, Arizona, in 2008.

  11. Electric and Magnetic Dipole States in ^238U

    Science.gov (United States)

    Hammond, S. L.; Adekola, A.; Angell, C. T.; Karwowski, H. J.; Howell, C. R.; Kwan, E.; Rusev, G.; Tonchev, A. P.; Tornow, W.; Kelley, J. H.

    2010-11-01

    An investigation of dipole states in ^238U is important for the fundamental understanding of its structure. Precise experimental information on the distribution of M1 and E1 transitions in ^238U has been obtained using the nuclear resonance fluorescence technique at the High-Intensity γ-ray Source at the Triangle Universities Nuclear Laboratory. Using 100% linearly-polarized, monoenergetic γ-ray beams between incident energies of 2.0 - 5.5 MeV, the spin, parity, width, and γ-strength of the ground-state deexcitations were determined. These measurements will form a unique data set that can be used for comparison with theoretical models of collective excitations in heavy, deformed nuclei. The data can also provide isotope-specific signatures to search for special nuclear materials.

  12. The importance of colloids and mires for the transport of uranium isotopes through the Kalix River watershed and Baltic Sea

    Science.gov (United States)

    Porcelli, D.; Andersson, P. S.; Wasserburg, G. J.; Ingri, J.; Baskaran, M.

    1997-10-01

    demonstrates that with efficient removal of uranium from solution, only small shifts in 234U/238U ratios can be generated in mirewater uranium. The measurements and model calculations show that mirewaters are not the primary source of the uranium in the river. Bedrock groundwaters with high 234U/238U ratios and uranium concentrations must be the dominant source of riverine uranium.

  13. Behaviour of {sup 238}U, {sup 234}U, {sup 228}Ra and {sup 226}Ra in rock alterations: study of Morungaba granitoids, SP-Brazil and ground water in its fractures; Comportamento de {sup 238}U, {sup 234}U, {sup 228}Ra e {sup 226}Ra na alteracao de rochas: estudo dos granitoides de Morungaba (SP) e aguas subterraneas de suas fraturas

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Rosana N. dos [Pontificia Univ. Catolica de Sao Paulo, SP (Brazil). Dept. de Fisica]. E-mail: rosana@pucsp.br; Marques, Leila S. [Sao Paulo Univ., SP (Brazil). Inst. de Astronomia, Geofisica e Ciencias Atmosfericas. Dept. de Geofisica]. E-mail: leila@iag.usp.br

    2005-07-01

    This work presents the first results obtained on the investigation of the behavior of uranium and radium radioisotopes in the processes of weathering and rock-water interaction of Morungaba granitoids belonging to Meridional Pluton (Valinhos Town-SP-Brazil). Specific activities of {sup 238}U, {sup 234}U, {sup 228}Ra and {sup 226}Ra were determined in non altered granitoids (Group A), as well as in those affected by different degrees of weathering (Groups B, C and D). The uranium specific activities were determined by alpha spectrometry method, whereas for the determination of radium isotopes high resolution gamma-ray spectrometry technique was employed. The data indicate that {sup 238}U and {sup 234}U are in radioactive equilibrium in the fresh analyzed granitoids, but show a slight depletion of {sup 234}U in relation to {sup 238}U in the weathered rocks. The ({sup 226}Ra/{sup 238}U) and ({sup 226}Ra/{sup 234}U) activity ratios of all investigated rocks are similar, showing a significant {sup 226}Ra depletion, which is probably caused by its preferential leaching. These results indicate that even samples macroscopically classified as fresh rocks, their systems have been opened for some geochemical changes. The high ({sup 234}U/{sup 238}U) activity ratios of groundwaters which are found in the fractures of these granitoids suggest their prolonged residence times in the aquifer and/or their percolation by other rocks presenting different geochemical properties. (author)

  14. Synthesis of superheavy nuclei with 238U target

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The production of superheavy nuclei with Z=108-116 via hot fusion reactions of the neutron-rich projectiles with 238U target is systematically studied.The results show that the production cross sections of superheavy nuclei do not decrease monotonously as the atomic number Z increasing.The cross sections of the superheavy nuclei at Z = 112 and 115 are enhanced as compared with the whole Z-trend in synthesis of the superheavy nuclei,which clearly illustrates that the reactions with large negative Q-value and shell correction are more favorable to synthesize superheavy nuclei.

  15. Synthesis of superheavy nuclei with 238U target

    Institute of Scientific and Technical Information of China (English)

    LIU ZuHua; BAO JingDong

    2009-01-01

    The production of superheavy nuclei with Z=108-116 via hot fusion reactions of the neutron-rich projectiles with 238u target is systematically studied.The results show that the production cross sections of superheavy nuclei do not decrease monotonously as the atomic number Z increasing.The cross sections of the superheavy nuclei at Z=112 and 115 are enhanced as compared with the whole Z-trend in synthesis of the superheavy nuclei,which clearly illustrates that the reactions with large negative Q-value and shell correction are more favorable to synthesize superheavy nuclei.

  16. 238 U, 232 Th and 40 K in wheat flour samples of Iraq markets

    Directory of Open Access Journals (Sweden)

    A. A.

    2014-09-01

    Full Text Available Introduction. Wheat flour is a nutritious type of food that is widely consumed by various age groups in Iraq. This study investigates the presence of long-lived gamma emitters in different type of wheat flour in Iraqi market. Materials and methods. Uranium ( 238 U, Thorium ( 232 Th and Potassium ( 40 K specific activity in (Bq/kg were measured in (12 different types of wheat flours that are available in Iraqi markets. The gamma spectrometry method with a NaI(Tl detector has been used for radiometric measurements. Also in this study we have calculated the internal hazard index, radium equivalent and absorbed dose rate in all samples. Results and discussion. It is found that the specific activity in wheat flour samples were varied from (1.086±0.0866 Bq/kg to (12.532±2.026 Bq/kg with an average (6.6025 Bq/kg for 238 U, For 232 Th From (0.126±0.066 Bq/kg to (4.298±0.388 Bq/kg with an average (1.9465Bq/kg and for 40 K from (41.842±5.875 Bq/kg to (264.729±3.843 Bq/kg with an average (133.097 Bq/kg. Also, it is found that the radium equivalent and the internal hazard index in wheat flour samples ranged from (3.4031 Bq/kg to (35.1523 Bq/kg with an average (19.6346 Bq/kg and from (0.0091 to (0.1219 with an average (0.0708 respectively. Conclusion. This study prove that the natural radioactivity and radiation hazard indices were lower than the safe.

  17. 238 U, 232 Th and 40 K in wheat flour samples of Iraq markets

    Directory of Open Access Journals (Sweden)

    Ali Abid Abojassim

    2015-05-01

    Full Text Available Introduction. Wheat flour is a nutritious type of food that is widely consumed by various age groups in Iraq. This study investigates the presence of long-lived gamma emitters in different type of wheat flour in Iraqi market. Materials and methods. Uranium (238 U, Thorium (232 Th and Potassium (40 K specific activity in (Bq/kg were measured in (12 different types of wheat flours that are available in Iraqi markets. The gamma spectrometry method with a NaI(Tl detector has been used for radiometric measurements. Also in this study we have calculated the internal hazard index, radium equivalent and absorbed dose rate in all samples. Results and discussion. It is found that the specific activity in wheat flour samples were varied from (1.086±0.0866 Bq/kg to (12.532±2.026 Bq/kg with an average (6.6025 Bq/kg for 238 U, For 232 Th From (0.126±0.066 Bq/kg to (4.298±0.388 Bq/kg with an average (1.9465Bq/kg and for 40 K from (41.842±5.875 Bq/kg to (264.729±3.843 Bq/kg with an average (133.097 Bq/kg. Also, it is found that the radium equivalent and the internal hazard index in wheat flour samples ranged from (3.4031 Bq/kg to (35.1523 Bq/kg with an average (19.6346 Bq/kg and from (0.0091 to (0.1219 with an average (0.0708 respectively. Conclusion. This study prove that the natural radioactivity and radiation hazard indices were lower than the safe.

  18. The activity concentrations of 40K, 226Ra, 232Th, 238U and 7Be in moss from spas in eastern Serbia in the period 2000-2012

    Directory of Open Access Journals (Sweden)

    Čučulović Ana

    2014-01-01

    Full Text Available In this work we present the activity concentrations of natural radionuclides 40K, 226Ra, 232Th, 238U and 7Be in mosses. One hundred and sixty-seven moss samples were collected between 2001 and 2012 from the territory of the Sokobanja, Banja Jošanica and Gamzigradska Banja spas. They were classified into 23 species. The activity concentrations (Bq/kg in moss from Sokobanja spa were: 40K 25-427; 226Ra 0.3-36; 232Th 1.0-37; 238U 0.4-28 and 7Be 29-210; from Banja Jošanica spa they were: 40K 90-242; 226Ra 2.4-11.7; 232Th 2.0-12.7; 238U 1.6-11.3 and 7Be 142-212; Gamzigradska Banja spa: 40K 95-351; 226Ra 8.0-21; 232Th 5.1-19; 238U 6.7-18 and 7Be 20-144. The activity concentrations of dominant natural radionuclides (potassium, radium, thorium and uranium in the moss samples were within the usual ranges for the territory of Serbia. [Projekat Ministarstva nauke Republike Srbije, br. III 43009

  19. Studying Nuclear Level Densities of 238U in the Nuclear Reactions within the Macroscopic Nuclear Models

    Science.gov (United States)

    Razavi, Rohallah; Rahmatinejad, Azam; Kakavand, Tayeb; Taheri, Fariba; Aghajani, Maghsood; Khooy, Asghar

    2016-02-01

    In this work the nuclear level density parameters of 238U have been extracted in the back-shifted Fermi gas model (BSFGM), as well as the constant temperature model (CTM), through fitting with the recent experimental data on nuclear level densities measured by the Oslo group. The excitation functions for 238U(p,2nα)233Pa, and 238U(p,4n)235Np reactions and the fragment yields for the fragments of the 238U(p,f) reaction have been calculated using obtained level density parameters. The results are compared to their corresponding experimental values. It was found that the extracted excitation functions and the fragment yields in the CTM coincide well with the experimental values in the low-energy region. This finding is according to the claim made by the Oslo group that the extracted level densities of 238U show a constant temperature behaviour.

  20. Determination of {sup 234}U/{sup 238}U isotope ratios in environmental waters by quadrupole ICP-MS after U stripping from alpha-spectrometry counting sources

    Energy Technology Data Exchange (ETDEWEB)

    Mas, Jose L.; Gonzalez-Labajo, Jesus [Universidad de Sevilla, Escuela Universitaria Politecnica, Departamento de Fisica Aplicada I, Sevilla (Spain); Ma, Renli [Northumbria University, School of Applied Sciences, Newcastle upon Tyne (United Kingdom); McLeod, Cameron; Cox, Alan [University of Sheffield, Department of Analytical Chemistry, Sheffield (United Kingdom); Watson, Paul [Elemental Scientific, Inc., Omaha, NE 68131 (United States)

    2006-09-15

    The {sup 234}U/{sup 238}U isotope ratio has been widely used as a tracer for geochemical processes in underground aquifers. Quadrupole-based inductively coupled plasma mass spectrometry (ICP-MS) equipped with a high-efficiency nebulizer and a membrane desolvator was employed for the determination of {sup 234}U/{sup 238}U isotope ratios in natural water samples. The instrumental limit of detection for {sup 234}U was at the low pg L{sup -1} level with very low sample consumption. Measurement precision ({sup 234}U/{sup 238}U) was 3-5% for bottled mineral water with elevated uranium concentration (>1 {mu}g L{sup -1}). For the analysis of groundwater samples from the Almonte-Marisma underground aquifer (Huelva, Spain), uranium was stripped from stainless steel planchets that had previously been used as radiometric counting sources for alpha-particle spectrometry. Potential spectral interferences from other metals introduced during the dissolution were investigated. Matrix-matched blank solutions were needed to subtract the background on {sup 234}U due to the formation of platinum argides, and to allow for mass bias correction and background correction. The Pt appears to be an impurity present in the stainless steel, either as a minor component by itself or after extraction from the anode and a subsequent uranium electrodeposition. The {sup 234}U/{sup 238}U isotope ratio data were in very good agreement with those of alpha spectrometry, while precision was improved by a factor of up to 10 and counting time was reduced down to {proportional_to}20 min (10 replicate measurements). (orig.)

  1. The metrological activity determination of {sup 238} U and {sup 230} Th by gamma spectrometry to industrial fuel-cycle application

    Energy Technology Data Exchange (ETDEWEB)

    Almeida M, M.C. de; Delgado, J.U.; Poledna, R. [Instituto de Radioprotecao e Dosimetria- IRD/SEMRA, CNEN, Av. Salvador Allende s/n, Recreio, CEP 22780-160, Rio de Janeiro (Brazil)]. e-mail: marcandida@yahoo.com.br

    2006-07-01

    This work describes the difficulty for determining the activity of {sup 238} U and {sup 230} Th using gamma spectrometry due to the low gamma-ray emission probabilities of 92 and 67 keV, and, mainly, the associated high uncertainties about 13 and 11%, respectively. {sup 230} Th is a {sup 238} U daughter and it is product from uranium mills and refineries. {sup 230} Th decays to {sup 226} Ra and this decay has to be measured because these radionuclides are not in secular equilibrium with their daughter products, besides the gamma-energies have high uncertainties in the emission probabilities. These radionuclides, mostly {sup 238} U, are important in the nuclear fuel-cycle, since the mining of uranium ore, where the nominal isotopic content of natural uranium is 99.27% of {sup 238} U, until the irradiated fuel reprocessing, where this isotope, a fertile material, is recovered to be used again. The uranium and thorium are considered safeguarded nuclear materials and the metrology tries to calibrate and standardize these materials to improve the activity determination techniques applied in different fuel-cycle scopes. The essential characteristics of the safeguarded materials are low gamma energies (less than 100 keV) and emission probabilities but with high uncertainties. In this way, the metrology can contribute to homeland security defense against illicit nuclear trafficking with the identification and quantification of the safeguarded radionuclides such as uranium and thorium, using specific gamma window energy and high resolution planar or coaxial germanium detector. The efficiency curve is obtained from the reference source spectrum considering the photopeak areas corresponding the standard activities. This curve depends on radiation energy, sample geometry, photon attenuation (sample absorption and material absorption between sample-detector), dead time and sample-detector position. The metrological activity determinations of {sup 238} U solid sources, and of

  2. Modeling the mobility of uranium from NORM-rich bedrock using multivariate statistical techniques - The mobility of uranium from U-containing bedrock materials as a function of pH: Implications for tunnel construction

    Energy Technology Data Exchange (ETDEWEB)

    Helmers, Tari; Fjermestad, Halldis; Salbu, Brit; Skipperud, Lindis [Norwegian University of Life Sciences, P.O. Box 5003, 1432 Aas (Norway); Meland, Sondre; Hagelia, Per [Norwegian Public Roads Administration, P.O. Box 8142, 0033 Oslo (Norway)

    2014-07-01

    According to amendments made to the Norwegian Pollution Control Act in 2011, naturally occurring radioactive material is now to be considered as an environmental contaminant, in addition to organic pollutants and trace metals. Environmental contamination is strongly correlated with the mobility and bioavailability of metals and radionuclides in natural systems. In order to determine the risk of environmental contamination from e.g. uranium (U) in alum shale areas, it is of particular importance to determine the mobility of U and trace metals found in the rock materials and their binding mechanisms. By determining the speciation and mobility of uranium and trace metals, better predictions can be made on the transport of contaminants in the environment from intervention like road and tunnel construction. The substrate media analyzed in this work was collected from a future tunnel construction site that is being built in the Gran municipality on National road Rv4 in Norway. The bedrock in the Gran municipality is rich in U-bearing minerals. Therefore, there is high potential for environmental contamination from the rock material removed for tunnel construction purposes. The present work focuses upon the effects of pH and the contact time (substrate media: solution) on the mobility of uranium. In order to identify the effects of pH and contact time on mobility, sample cores collected from an area rich in alum shale were subjected to an extended leaching experiment. In this experiment, the substrate materials were treated with five different pH solutions and were analyzed for different contact times. In addition, the results were compared to data from a sequential extraction experiment. In the leaching experiment, the mobilization of uranium in all of the substrate material was affected by the pH of solution. All of the samples were capable of quickly buffering pH solutions with a pH as low as 4 to neutral-alkaline conditions, attributed to the carbonate minerals

  3. Prospects of heavy and superheavy element production via inelastic nucleus-nucleus collisions - from 238U+238U to18O+254Es

    Science.gov (United States)

    Schädel, Matthias

    2016-12-01

    Multi-nucleon transfer reactions, frequently termed deep-inelastic, between heavy-ion projectiles and actinide targets provide prospects to synthesize unknown isotopes of heavy actinides and superheavy elements with neutron numbers beyond present limits. The 238U on 238U reaction, which revealed essential aspects of those nuclear reactions leading to surviving heavy nuclides, mainly produced in 3n and 4n evaporation channels, is discussed in detail. Positions and widths of isotope distributions are compared. It is shown, as a general rule, that cross sections peak at irradiation energies about 10% above the Coulomb barrier. Heavy target nuclei are essential for maximizing cross sections. Experimental results from the 238U on 248Cm reaction, including empirical extrapolations, are compared with theoretical model calculations predicting relatively high cross sections for neutron-rich nuclei. Experiments to test the validity of such predictions are proposed. Comparisons between rather symmetric heavy-ion reactions like 238U on 248Cm (or heavier targets up to 254Es) with very asymmetric ones like 18O on 254Es reveal that the ones with 238U as a projectile have the highest potential in the superheavy element region while the latter ones can be advantageous for the synthesis of heavy actinide isotopes. Concepts for highly efficient recoil separators designed for transfer products are presented.

  4. The estuarine chemistry and isotope systematics of 234,238U in the Amazon and Fly Rivers

    Science.gov (United States)

    Swarzenski, P.; Campbell, P.; Porcelli, D.; McKee, B.

    2004-01-01

    Natural concentrations of 238U and ??234U values were determined in estuarine surface waters and pore waters of the Amazon and Fly (Papua New Guinea) Rivers to investigate U transport phenomena across river-dominated land-sea margins. Discharge from large, tropical rivers is a major source of dissolved and solid materials transported to the oceans, and are important in defining not only oceanic mass budgets, but also terrestrial weathering rates. On the Amazon shelf, salinity-property plots of dissolved organic carbon, pH and total suspended matter revealed two vastly contrasting water masses that were energetically mixed. In this mixing zone, the distribution of uranium was highly non-conservative and exhibited extensive removal from the water column. Uranium removal was most pronounced within a salinity range of 0-16.6, and likely the result of scavenging and flocculation reactions with inorganic (i.e., Fe/Mn oxides) and organic colloids/particles. Removal of uranium may also be closely coupled to exchange and resuspension processes at the sediment/water interface. An inner-shelf pore water profile indicated the following diagenetic processes: extensive (???1 m) zones of Fe(III) - and, to a lesser degree, Mn(IV) - reduction in the absence of significant S(II) concentrations appeared to facilitate the formation of various authigenic minerals (e.g., siderite, rhodocrosite and uraninite). The pore water dissolved 238U profile co-varied closely with Mn(II). Isotopic variations as evidenced in ??234U pore waters values from this site revealed information on the origin and history of particulate uranium. Only after a depth of about 1 m did the ??234U value approach unity (secular equilibrium), denoting a residual lattice bound uranium complex that is likely an upper-drainage basin weathering product. This suggests that the enriched ??234U values represent a riverine surface complexation product that is actively involved in Mn-Fe diagenetic cycles and surface

  5. 206Pb-230Th-234U-238U and 207Pb-235U geochronology of Quaternary opal, Yucca Mountain, Nevada

    Science.gov (United States)

    Neymark, Leonid A.; Amelin, Yuri V.; Paces, James B.

    2000-01-01

    U–Th–Pb isotopic systems have been studied in submillimeter-thick outermost layers of Quaternary opal occurring in calcite–silica fracture and cavity coatings within Tertiary tuffs at Yucca Mountain, Nevada, USA. These coatings preserve a record of paleohydrologic conditions at this site, which is being evaluated as a potential high-level nuclear waste repository. The opal precipitated from groundwater is variably enriched in 234U (measured 234U/238U activity ratio 1.124–6.179) and has high U (30–313 ppm), low Th (0.008–3.7 ppm), and low common Pb concentrations (measured 206Pb/204Pb up to 11,370). It has been demonstrated that the laboratory acid treatment used in this study to clean sample surfaces and to remove adherent calcite, did not disturb U–Th–Pb isotopic systems in opal. The opal ages calculated from 206Pb∗/238U and 207Pb∗/235U ratios display strong reverse discordance because of excess radiogenic 206Pb∗ derived from the elevated initial 234U. The data are best interpreted using projections of a new four-dimensional concordia diagram defined by 206Pb∗/238U, 207Pb∗/235U, 234U/238Uactivity, and 230Th/238Uactivity. Ages and initial 234U/238U activity ratios have been calculated using different projections of this diagram and tested for concordance. The data are discordant, that is observed 207Pb∗/235U ages of 170 ± 32 (2σ) to 1772 ± 40 ka are systematically older than 230Th/U ages of 34.1 ± 0.6 to 452 ± 32 ka. The age discordance is not a result of migration of uranium and its decay products under the open system conditions, but a consequence of noninstantaneous growth of opal. Combined U–Pb and 230Th/U ages support the model of slow mineral deposition at the rates of millimeters per million years resulting in layering on a scale too fine for mechanical sampling. In this case, U–Pb ages provide more accurate estimates of the average age for mixed multiage samples than 230Th/U ages, because ages based on shorter

  6. Determination of {sup 234}U and {sup 238}U activity concentrations in groundwaters from three deep wells drilled in Itu Intrusive Suite (SP); Determinacao das concentracoes de atividade de {sup 234}U e {sup 238}U em aguas subterraneas de tres pocos perfurados em rochas da Suite Intrusiva de Itu (SP)

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Francisca de

    2006-07-01

    Activity concentrations of ({sup 234}U) and ({sup 238}U) were determined in groundwaters drawn from three deep wells drilled in rocks from Itu Intrusive Suite (SP), two located in Salto town (S and SY wells) and the other one in Itu (I well). Sampling was done from September, 2004 to December, 2005, and twelve samples of each well were collected monthly. For those determinations alpha spectrometry technique was used, providing high precision results, as shown by the very good agreement of the data obtained in the analyses of 23 duplicates. The waters from the three wells presented a considerable enrichment of {sup 234}U in relation to {sup 238}U, indicating an important radioactive disequilibrium of these isotopes. In well I, the activity concentrations of ({sup 238}U) varied from (1,06 +- 0,03) to (2,1+- 0,2) mBq/L and those of ({sup 234}U) spanned from (3,1 +- 0,2) to (6,0 +- 0,4) mBq/L, whereas ({sup 234}U/{sup 238}U) activity ratios did not present significant variation, during the sampling time interval, presenting an average of 2,8 +- 0,1. The S waters showed the lowest uranium concentrations and the largest diversity of ({sup 238}U) and ({sup 234}U) activity concentrations, which varied from (0,26 +- 0,02) to (1,07+- 0,08) mBq/L and from (1,8 +- 0,1) to (7,0 +- 0,5) mBq/L, respectively, and also presented variable ({sup 234}U/{sup 238}U) activity ratios, spanning from (2,79 +- 0,07) to (8,1+- 0,3). In SY well, ({sup 238}U) activities varied between (0,8 +- 0,1) and (4,2 +- 0,3) mBq/L and those ones of ({sup 234}U) from (14 +- 1) to (53 +- 4) mBq/L, whereas ({sup 234}U/{sup 238}U) ratios fell in the interval from 12,6 +- 0,3 to 18,3 +- 0,4, with the highest activities of both radioisotopes registered during the dry season and the lowest ones in the rainy time period. The ({sup 234}U/{sup 238}U) activity ratios, which were invariable during sampling period of well I, indicated the contribution of rainfall to recharge the aquifer. The observed correlation

  7. Uranium and radon in private bedrock well water in Maine: geospatial analysis at two scales

    Science.gov (United States)

    Yang, Qiang; Smitherman, Paul; Hess, C.T.; Culbertson, Charles W.; Marvinney, Robert G.; Zheng, Yan

    2014-01-01

    In greater Augusta of central Maine, 53 out of 1093 (4.8%) private bedrock well water samples from 1534 km2 contained [U] >30 μg/L, the U.S. Environmental Protection Agency’s (EPA) Maximum Contaminant Level (MCL) for drinking water; and 226 out of 786 (29%) samples from 1135 km2 showed [Rn] >4,000 pCi/L (148 Bq/L), the U.S. EPA’s Alternative MCL. Groundwater pH, calcite dissolution and redox condition are factors controlling the distribution of groundwater U but not Rn due to their divergent chemical and hydrological properties. Groundwater U is associated with incompatible elements (S, As, Mo, F, and Cs) in water samples within granitic intrusions. Elevated [U] and [Rn] are located within 5–10 km distance of granitic intrusions but do not show correlations with metamorphism at intermediate scales (100−101 km). This spatial association is confirmed by a high-density sampling (n = 331, 5–40 samples per km2) at local scales (≤10–1 km) and the statewide sampling (n = 5857, 1 sample per 16 km2) at regional scales (102–103 km). Wells located within 5 km of granitic intrusions are at risk of containing high levels of [U] and [Rn]. Approximately 48 800–63 900 and 324 000 people in Maine are estimated at risk of exposure to U (>30 μg/L) and Rn (>4000 pCi/L) in well water, respectively.

  8. Uranium and radon in private bedrock well water in Maine: geospatial analysis at two scales.

    Science.gov (United States)

    Yang, Qiang; Smitherman, Paul; Hess, C T; Culbertson, Charles W; Marvinney, Robert G; Smith, Andrew E; Zheng, Yan

    2014-04-15

    In greater Augusta of central Maine, 53 out of 1093 (4.8%) private bedrock well water samples from 1534 km(2) contained [U] >30 μg/L, the U.S. Environmental Protection Agency's (EPA) Maximum Contaminant Level (MCL) for drinking water; and 226 out of 786 (29%) samples from 1135 km(2) showed [Rn] >4,000 pCi/L (148 Bq/L), the U.S. EPA's Alternative MCL. Groundwater pH, calcite dissolution and redox condition are factors controlling the distribution of groundwater U but not Rn due to their divergent chemical and hydrological properties. Groundwater U is associated with incompatible elements (S, As, Mo, F, and Cs) in water samples within granitic intrusions. Elevated [U] and [Rn] are located within 5-10 km distance of granitic intrusions but do not show correlations with metamorphism at intermediate scales (10(0)-10(1) km). This spatial association is confirmed by a high-density sampling (n = 331, 5-40 samples per km(2)) at local scales (≤10(-1) km) and the statewide sampling (n = 5857, 1 sample per 16 km(2)) at regional scales (10(2)-10(3) km). Wells located within 5 km of granitic intrusions are at risk of containing high levels of [U] and [Rn]. Approximately 48 800-63 900 and 324 000 people in Maine are estimated at risk of exposure to U (>30 μg/L) and Rn (>4000 pCi/L) in well water, respectively.

  9. Neutron and fission yields from high-energy deuterons in infinite /sup 238/U targets

    Energy Technology Data Exchange (ETDEWEB)

    Canfield, E.

    1965-06-28

    Early work on the interaction of high energy deuterons with large /sup 238/U targets is reexamined and current theoretical study is discussed. Results of fission and neutron yield calculations are compared with experiment. (SDF)

  10. Experimental determination of the antineutrino spectrum of the fission products of {sup 238}U

    Energy Technology Data Exchange (ETDEWEB)

    Haag, Nils-Holger

    2013-10-09

    Fission of {sup 238}U contributes about 10 % to the antineutrino emission of a pressurized water reactor. In the present thesis, the beta spectrum of the fission products of {sup 238}U was determined in an experiment at the neutron source FRM II. This beta spectrum was subsequently converted into an antineutrino spectrum. This first measurement of the antineutrino spectrum supports all current and future reactor antineutrino experiments.

  11. The Application of 238U/235U as a Redox-Proxy for Past Ocean Chemistry

    Science.gov (United States)

    Andersen, M. B.; Westermann, S.; Bahniuk, A.; Vasconcelos, C.; McKenzie, J. A.; Föllmi, K. B.; Vance, D.

    2014-12-01

    The recent discovery of significant variation in 238U/235U caused by redox change at the surface Earth has led to its use to extract information on the oxygenation state of ancient oceans from marine sediments [e.g. 1]. Recent studies have focused on improving the understanding of the 238U/235U signature in modern marine carbonates [2] and black shales [3] to improve the robustness of this tracer. To further advance its use we have focused on improving our understanding of 238U/235U systematics in modern dolomite, another commonly occurring rock-type in the geological record, before turning to 238U/235U signatures in ancient sediments. The measured dolomite samples, precipitated in modern environments of coastal hypersaline lagoons in Brazil, all exhibit 238U/235U values that deviate from the seawater composition [3]. Observed values are both lighter (ca. 130 ppm; as also observed in dolomite from tidal-ponds on Bahamas [2]) and heavier (50-180 ppm). These distinct 238U/235U values for different dolomite-precipitates likely attest to the particular formation style, as well as early diagenetic processes. We use such modern settings to discuss the utility of 238U/235U in ancient sediments, the singularity of any observed 238U/235U signal, its relation to global ocean chemistry and potential diagenetic overprinting. These constraints are then used to evaluate a well-preserved marine carbonate section [4] and published black shale 238U/235U data [1], both deposited during the Oceanic Anoxic Event 2 (93 Ma). We discuss the capabilities of both the carbonate and black shale section for retaining information on the 238U/235U composition in the ocean during OAE 2. [1] Montoya-Pino et al. (2010) Geology, 38, 315-318 [2] Romaniello et al. (2013) 362, 305-316 [3] Andersen et al. (2014) EPSL, 400, 184-194 [4] Westermann et al. (2010) Cret. Res., 31, 500-514

  12. Influence of soil texture on the distribution and availability of {sup 238}U, {sup 230}Th, and {sup 226}Ra in soils

    Energy Technology Data Exchange (ETDEWEB)

    Blanco Rodriguez, P. [Departamento de Fisica, Facultad de Ciencias, Universidad de Extremadura, Avd. Elvas s/n, 06071 Badajoz (Spain); Vera Tome, F. [Departamento de Fisica Aplicada, Facultad de Ciencias, Universidad de Extremadura, Avd. Elvas s/n, 06071 Badajoz (Spain)], E-mail: fvt@unex.es; Lozano, J.C. [Laboratorio de Radiactividad Ambiental, Facultad de Ciencias, Universidad de Salamanca, 37008 Salamanca (Spain); Perez-Fernandez, M.A. [Area de Ecologia, Universidad Pablo Olavide, Carretera de Utrera km. 1, 41013 Sevilla (Spain)

    2008-08-15

    The influence of soil texture on the distribution and availability of {sup 238}U, {sup 230}Th, and {sup 226}Ra in soils was studied in soil samples collected at a rehabilitated uranium mine located in the Extremadura region in south-west Spain. The activity concentration (Bq kg{sup -1}) in the soils ranged from 60 to 750 for {sup 238}U, from 60 to 260 for {sup 230}Th, and from 70 to 330 for {sup 226}Ra. The radionuclide distribution was determined in three soil fractions: coarse sand (0.5-2 mm), medium-fine sand (0.067-0.5 mm), and silt and clay (<0.067 mm). The relative mobility of the natural radionuclides in the different fractions was studied by comparison of the activity ratios between radionuclides belonging to the same radioactive series. The lability of these radionuclides in each fraction was also studied through selective extraction from the soils using a one-step sequential extraction scheme. Significant correlations were found for {sup 238}U, {sup 230}Th, and {sup 226}Ra between the activity concentration per fraction and the total activity concentration in the bulk soil. Thus, from the determination of the activity concentration in the bulk soil, one could estimate the activity concentration in each fraction. Correlations were also found for {sup 238}U and {sup 226}Ra between the labile activity concentration in each fraction and the total activity concentration in bulk soil. Assuming that there is some particle-size fraction that predominates in the process of soil-to-plant transfer, the parameters obtained in this study should be used as correction factors for the transfer factors determined from the bulk soil in previous studies.

  13. The radiochemical contamination (210Po and 238U of zone around phosphogypsum waste heap in Wiślinka (northern Poland

    Directory of Open Access Journals (Sweden)

    Boryło A.

    2013-04-01

    Full Text Available The aim of this work was the determination of the impact of phosphogypsum waste heap in Wiślinka (northern Poland for radiological protection of zone around waste heap. The activity of 210Po, 234U, and 238U were measured using an alpha spectrometer. The values of uranium and polonium concentration in water with immediate area of waste heap are considerably higher than in the waters of the Martwa Wisła river. The values of activity ratio 234U/238U are approximately about one in the phosphogypsum (0.97±0.05 and in the water of retention reservoir and pumping station (0.92±0.01 and 0.99±0.08, while in the water from the Martwa Wisła river they are slightly higher than one (1.03±0.07 and 1.17±0.06. In the analyzed plants species the highest amounts of polonium and uranium were found in ruderal plants samples as well as hygrophilous plant samples. The more amounts of 210Po and 238U radionuclides were accumulated mainly in the roots of the analyzed plant species. The significant source of polonium and uranium in the natural environment is dry and wet atmospheric fallout in the immediate vicinity of phosphogypsum waste heap and the transfer via root for distant areas. The general conclusion of realized study is higher influence of phosphogypsum on radioactive contamination of environmental zone around heap waste in Wiślinka (northern Poland.

  14. EXCALIBUR-at-CALIBAN: a neutron transmission experiment for {sup 238}U(n,n'{sub continuum}γ) nuclear data validation

    Energy Technology Data Exchange (ETDEWEB)

    Bernard, David; Leconte, Pierre; Destouches, Christophe [CEA, DEN, DER, SPRC et SPEX, Cadarache F-13108 SAINT-PAUL-LEZ-DURANCE (France); Casoli, Pierre; Chambru, Laurent; Chanussot, Didier; Chateauvieux, Herve; Gevrey, Gaetan; Guilbert, Frederique; Lereuil, Hugues; Rousseau, Guillaume; Schaub, Muriel [CEA, DAM, Valduc F-21120 IS-SUR-TILLE (France); Heusch, Murielle; Meplan, Olivier; Ramdhane, Mourad [CNRS/IN2P3, 53 rue des Martyrs, F-38026 Grenoble, Cedex (France)

    2015-07-01

    Two recent papers justified a new experimental program to give a new basis for the validation of {sup 238}U nuclear data, namely neutron induced inelastic scattering and transport codes at neutron fission energies. The general idea is to perform a neutron transmission experiment through natural uranium material. As shown by Hans Bethe, neutron transmissions measured by dosimetric responses are linked to inelastic cross sections. This paper describes the principle and the results of such an experience called EXCALIBUR performed recently (January and October 2014) at the CALIBAN reactor facility. (authors)

  15. Biological availability of (238)U, (234)U and (226)Ra for wild berries and meadow grasses in natural ecosystems of Belarus.

    Science.gov (United States)

    Sokolik, G A; Ovsiannikova, S V; Voinikava, K V; Ivanova, T G; Papenia, M V

    2014-01-01

    This work is devoted to investigation of behavior of (234)U, (238)U and (226)Ra by determining the soil to plant transfer under different natural conditions such as forest or swamped areas and meadow lands with different soil types. The paper summarizes the data on investigation of uranium and radium uptake by wild berries and natural meadow grasses in the typical conditions of Belarus. Parameters characterizing the biological availability of (234)U, (238)U and (226)Ra for bilberry (Vaccinium myrtillus), lingonberry (Vaccinium viti-idaea), blueberry (Vaccinium iliginosum) and cranberry (Vaccinium oxycoccus palustris) as well as for widely occurring mixed meadow vegetation, which belongs to the sedge-grass or grass-sedge associations and forbs, have been established. In the sites under investigation, the deposition levels of (238+239+240)Pu were less than 0.37 kBq m(-2) and (137)Cs deposition ranged between less than 0.37 and 37 kBq m(-2). It was found that activity concentrations of radionuclides in berries varied in the ranges of 0.037-0.11 for (234)U, 0.036-0.10 for (238)U and 0.11-0.43 Bq kg(-1) for (226)Ra, but in the mixed meadow grasses they were 0.32-4.4, 0.24-3.9 and 0.14-6.9 Bq kg(-1) accordingly. The (234)U/(238)U activity ratios were 1.02 ± 0.01 for wild berries, 1.20 ± 0.09 for underground meadow grasses and 1.02 ± 0.02 for proper soils. The concentration ratios (CRs, dry weight basis) of (234)U and (238)U for mixed meadow grasses were 0.036-0.42 and 0.041-0.46 respectively. The correspondent geometric means (GM) were 0.13 and 0.15 with geometric standard deviations (GSD) of 2.4. The CRs of (226)Ra for meadow grasses were 0.031-1.0 with GM 0.20 and GSD 2.6. The CRs of (234)U, (238)U and (226)Ra for wild berries ranged within 0.0018-0.008 (GM is 0.0034, GSD is 1.8), 0.0018-0.008 (GM is 0.0035, GSD is 1.8) and 0.005-0.033 (GM is 0.016, GSD is 2.1) accordingly. The highest CR values of uranium for mixed meadow grasses were found in the

  16. Transmission Nuclear Resonance Fluorescence Measurements of 238U in Thick Targets

    Energy Technology Data Exchange (ETDEWEB)

    Quiter, Brian J.; Ludewigt, Bernhard A.; Mozin, Vladimir V.; Wilson, Cody; Korbly, Steve

    2010-08-31

    Transmission nuclear resonance fluorescence measurements were made on targets consisting of Pb and depleted U with total areal densities near 86 g/cm2. The 238U content n the targets varied from 0 to 8.5percent (atom fraction). The experiment demonstrates the capability of using transmission measurements as a non-destructive technique to identify and quantify the presence of an isotope in samples with thicknesses comparable to he average thickness of a nuclear fuel assembly. The experimental data also appear to demonstrate the process of notch refilling with a predictable intensity. Comparison of measured spectra to previous backscatter 238U measurements indicates general agreement in observed excited states. Two new 238U excited states and possibly a third state have also been observed.

  17. Arsenic, iron, lead, manganese, and uranium concentrations in private bedrock wells in southeastern New Hampshire, 2012-2013

    Science.gov (United States)

    Flanagan, Sarah M.; Belaval, Marcel; Ayotte, Joseph D.

    2014-01-01

    Trace metals, such as arsenic, iron, lead, manganese, and uranium, in groundwater used for drinking have long been a concern because of the potential adverse effects on human health and the aesthetic or nuisance problems that some present. Moderate to high concentrations of the trace metal arsenic have been identified in drinking water from groundwater sources in southeastern New Hampshire, a rapidly growing region of the State (Montgomery and others, 2003). During the past decade (2000–10), southeastern New Hampshire, which is composed of Hillsborough, Rockingham, and Strafford Counties, has grown in population by nearly 48,700 (or 6.4 percent) to 819,100. These three counties contain 62 percent of the State’s population but encompass only about 22 percent of the land area (New Hampshire Office of Energy and Planning, 2011). According to a 2005 water-use study (Hayes and Horn, 2009), about 39 percent of the population in these three counties in southeastern New Hampshire uses private wells as sources of drinking water, and these wells are not required by the State to be routinely tested for trace metals or other contaminants. Some trace metals have associated human-health benchmarks or nonhealth guidelines that have been established by the U.S. Environmental Protection Agency (EPA) to regulate public water supplies. The EPA has established a maximum contaminant level (MCL) of 10 micrograms per liter (μg/L) for arsenic (As) and a MCL of 30 μg/L for uranium (U) because of associated health risks (U.S. Environmental Protection Agency, 2012). Iron (Fe) and manganese (Mn) are essential for human health, but Mn at high doses may have adverse cognitive effects in children (Bouchard and others, 2011; Agency for Toxic Substances and Disease Registry, 2012); therefore, the EPA has issued a lifetime health advisory (LHA) of 300 μg/L for Mn. Recommended secondary maximum contaminant levels (SMCLs) for Fe (300 μg/L) and Mn (50 μg/L) were established primarily as

  18. Trace element distribution and 235U/238U ratios in Euphrates waters and in soils and tree barks of Dhi Qar province (southern Iraq).

    Science.gov (United States)

    Riccobono, Francesco; Perra, Guido; Pisani, Anastasia; Protano, Giuseppe

    2011-09-01

    To assess the quality of the environment in southern Iraq after the Gulf War II, a geochemical survey was carried out. The survey provided data on the chemistry of Euphrates waters, as well as the trace element contents, U and Pb isotopic composition, and PAH levels in soil and tree bark samples. The trace element concentrations and the (235)U/(238)U ratio values in the Euphrates waters were within the usual natural range, except for the high contents of Sr due to a widespread presence of gypsum in soils of this area. The trace element contents in soils agreed with the common geochemistry of soils from floodplain sediments. Some exceptions were the high contents of Co, Cr and Ni, which had a natural origin related to ophiolitic outcrops in the upper sector of the Euphrates basin. The high concentrations of S and Sr were linked to the abundance of gypsum in soils. A marked geochemical homogeneity of soil samples was suggested by the similar distribution pattern of rare earth elements, while the (235)U/(238)U ratio was also fairly homogeneous and within the natural range. The chemistry of the tree bark samples closely reflected that of the soils, with some notable exceptions. Unlike the soils, some tree bark samples had anomalous values of the (235)U/(238)U ratio due to mixing of depleted uranium (DU) with the natural uranium pool. Moreover, the distribution of some trace elements (such as REEs, Th and Zr) and the isotopic composition of Pb in barks clearly differed from those of the nearby soils. The overall results suggested that significant external inputs occurred implying that once formed the DU-enriched particles could travel over long distances. The polycyclic aromatic hydrocarbon concentrations in tree bark samples showed that phenanthrene, fluoranthene and pyrene were the most abundant components, indicating an important role of automotive traffic.

  19. Standard practice for the determination of 237Np, 232Th, 235U and 238U in urine by inductively coupled plasma-Mass spectrometry (ICP-MS) and gamma ray spectrometry.

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2005-01-01

    1.1 This practice covers the separation and preconcentration of neptunium-237 (237Np), thorium-232 (232Th), uranium-235 (235U) and uranium-238 (238U) from urine followed by quantitation using ICP-MS. 1.2 This practice can be used to support routine bioassay programs. The minimum detectable concentrations (MDC) for this method, taking the preconcentration factor into account, are approximately 1E-2Bq for 237Np (0.38ng), 2E-6Bq for 232Th (0.50ng), 4E-5Bq for 235U (0.50ng) and 6E-6Bq for 238U (0.48ng). 1.3 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  20. Transfer of {sup 238}U, {sup 230}Th, {sup 226}Ra, and {sup 210}Pb from soils to tree and shrub species in a Mediterranean area

    Energy Technology Data Exchange (ETDEWEB)

    Blanco Rodriguez, P. [Natural Radioactivity Group, Facultad de Ciencias, Universidad de Extremadura, Avda. de Elvas s/n, 06071 Badajoz (Spain); Vera Tome, F. [Natural Radioactivity Group, Facultad de Ciencias, Universidad de Extremadura, Avda. de Elvas s/n, 06071 Badajoz (Spain)], E-mail: fvt@unex.es; Lozano, J.C. [Natural Radioactivity Group, Facultad de Ciencias, Universidad de Extremadura, Avda. de Elvas s/n, 06071 Badajoz (Spain); Laboratorio de Radiaciones Ionizantes, Facultad de Ciencias, Universidad de Salamanca, 37008 Salamanca (Spain); Perez Fernandez, M.A. [Natural Radioactivity Group, Facultad de Ciencias, Universidad de Extremadura, Avda. de Elvas s/n, 06071 Badajoz (Spain); Area de Ecologia, Universidad Pablo Olavide, Carretera de Utrera km. 1, 41013 Sevilla (Spain)

    2010-06-15

    The soil-to-plant transfer factors of natural uranium isotopes ({sup 238}U and {sup 234}U), {sup 230}Th, {sup 226}Ra, and {sup 210}Pb were studied in a disused uranium mine located in the Extremadura region in the south-west of Spain. The plant samples included trees (Quercus ilex, Quercus suber, and Eucalyptus cameldulensis) and one shrub (Cytisus multiflorus). All of them are characteristic of Mediterranean environments. The activity concentrations in leaves and fruit were determined for the tree species at different stages of growth. For the shrub, the total above-ground fraction was considered in three seasons. For old leaves and fruit, the highest activity concentrations were found in Eucalyptus cameldulensis for all the radionuclides studied, except in the case of {sup 230}Th that presented similar activity concentrations in all of the tree species studied. In every case, the transfer to fruit was less than the transfer to leaves. In the shrub, the results depended on the season of sampling, with the highest value obtained in spring and the lowest in autumn. Important correlations were obtained for {sup 238}U and {sup 226}Ra between the activity ratio in soils with that in leaves or fruit.

  1. Study of fusion-fission dynamics in 19F+238U reaction

    Directory of Open Access Journals (Sweden)

    Dubey R.

    2016-01-01

    Full Text Available Mass angle distribution measurements for 19F+238U reaction were carried out around the sub barrier energies. Mass angle correlation has not been observed at above and below the fusion barrier in present reaction. This infer the minimal presence of non compound like events at these bombarding energies range.

  2. Energy dependence of 238U fission yields investigated in inverse kinematics

    Directory of Open Access Journals (Sweden)

    Veselsky M.

    2010-03-01

    Full Text Available The production cross sections of neutron-rich fission residues produced in reactions induced by a 238U beam impinging onto Pb and Be targets were investigated at the Fragment Separator (FRS at GSI using the inverse kinematic technique. These data allowed us to discuss the optimum energies in fission for producing the most neutron-rich residues.

  3. Magmatic Processes at Loihi Seamount Inferred From 226Ra-230Th-234U-238U Disequilibria

    Science.gov (United States)

    Pietruszka, A. J.; Hauri, E. H.; Garcia, M. O.

    2001-12-01

    We have conducted a detailed study of the U-series isotope geochemistry of young tholeiitic, transitional and alkalic Loihi basalts to examine the melt generation process during the preshield stage of a Hawaiian volcano. A previous study (Sims et al. 1999; GCA, v. 63) of two dredged lavas from the deep flanks of Loihi found a higher (230Th/238U) activity ratio in an alkalic basalt (1.07) compared to a tholeiitic basalt (1.04). This difference suggests that the tholeiitic basalt may have formed at a higher rate of mantle upwelling than the alkalic basalt. Our samples were collected from surface lava flows at Loihi's summit and along the volcano's south rift zone by submersible. Analyses were preformed using high-precision plasma ionization mass spectrometry. The samples display a relatively large range in the amount of excess 226Ra (0-13%) that extends to much lower values than observed at Kilauea Volcano (11-12%). The low (226Ra/230Th) ratios of Loihi lavas probably result from post-eruptive decay of 226Ra and imply eruption ages of 0-12 kyr. All of the Loihi samples (including the 1996 lava) have small amounts of excess 234U (0.2-0.8%). The most likely source for (234U/238U)>1 at Loihi is seawater, which has (234U/238U)=1.14. Since all of the samples were fresh, hand-picked glasses, these elevated (234U/238U) ratios may have resulted from the assimilation of a seawater-derived component within Loihi's magmatic plumbing system rather than post-eruptive U addition. The range of (230Th/238U) that we measured is 1.01-1.07, which is larger than the previous range known for Loihi. Mass balance calculations using the measured (234U/238U) ratios suggest that 1-6% of the U in the samples that we analyzed is ultimately derived from seawater. Correcting the 230Th-238U disequilibria of the Loihi lavas for this seawater-derived U results in a narrower range in the amount of excess 230Th (6-9%) with no significant differences between tholeiitic, transitional or alkalic basalts

  4. 238U-234U activity ratio as tracer of waterpathway within the watershed substratum: evidence of U data from the Strengbach and Ringelbach research catchments (Vosges , France)

    Science.gov (United States)

    Chabaux, F.; Schaffhausen, Th.; Pierret, M.-C.; Ambroise, B.

    2012-04-01

    U activity ratios were measured in spring and source waters collected in two small research watersheds developed on granitic bedrocks in Vosges Mountains (Eastern France), i.e., the Strengbach (http://ohge.u-strasbg.fr) and the Ringelbach catchments. The data indicates a clear relationship between the emerging altitude of sources/springs in each slope of the watersheds, and the intensity of 234U-238U activity ratios in the waters. Such a relationship can be readily explained through a scenario assuming that U mobilization in these waters and their 234U enrichment (consequence of the alpha recoil process) are controlled by the duration of the water-pathway within the substratum of the watershed: longer water pathway within the watershed, longer duration of water-rock interaction and hence higher 234U enrichment in the source/spring waters. The immediate consequence of such an interpretation is that (234U/238U) activity ratio in surface waters, at least at the scale of such small and elemental watersheds, might be a geochemical tracer useful to constrain a key hydrological parameter which controls, at least partly, the nature and the intensity of water-rock interactions in the watershed, namely the water pathway within the watershed substratum. The data also suggests that U activity ratios could be also very relevant to constrain the contribution of deep waters within surface waters. Future developments in this domain will certainly confirm the interest of U activity ratio as hydrological tracer of the water-rock interactions.

  5. Studying nuclear level densities of {sup 238}U in the nuclear reactions within the macroscopic nuclear models

    Energy Technology Data Exchange (ETDEWEB)

    Razavi, Rohallah; Aghajani, Maghsood; Khooy, Asghar [Imam Hossein Comprehensive Univ., Tehran (Iran, Islamic Republic of). Dept. of Physics; Rahmatinejad, Azam; Taheri, Fariba [Univ. of Zanjan (Iran, Islamic Republic of). Dept. of Physics; Kakavand, Tayeb [Imam Khomeini International Univ., Qazvin (Iran, Islamic Republic of). Dept. of Physics

    2016-05-01

    In this work the nuclear level density parameters of {sup 238}U have been extracted in the back-shifted Fermi gas model (BSFGM), as well as the constant temperature model (CTM), through fitting with the recent experimental data on nuclear level densities measured by the Oslo group. The excitation functions for {sup 238}U(p,2nα){sup 233}Pa, and {sup 238}U(p,4n){sup 235}Np reactions and the fragment yields for the fragments of the {sup 238}U(p,f) reaction have been calculated using obtained level density parameters. The results are compared to their corresponding experimental values. It was found that the extracted excitation functions and the fragment yields in the CTM coincide well with the experimental values in the low-energy region. This finding is according to the claim made by the Oslo group that the extracted level densities of {sup 238}U show a constant temperature behaviour.

  6. {sup 230}Th, {sup 232}Th and {sup 238}U determinations in phosphoric acid fertilizer and process products by ICP-MS

    Energy Technology Data Exchange (ETDEWEB)

    Nascimento, Marcos R.L. do; Guerreiro, Luisa M.R.; Bonifacio, Rodrigo L.; Taddei, Maria H.T., E-mail: pmarcos@cnen.gov.br [Comissao Nacional de Energia Nuclear (LAPOC/CNEN-MG), Pocos de Caldas, MG (Brazil). Laboratorio de Pocos de Caldas

    2015-07-01

    Through processing of Santa Quiteria-CE mine phosphate rock, Brazil has established a project for production of phosphoric acid fertilizer and uranium as a by-product. Under leaching conditions of phosphate rock with sulfuric acid, which is the common route for preparing phosphoric acid fertilizer, a large part of uranium, thorium and their decay products naturally present in the rock are solubilized. In order to assess the contamination potential in phosphoric acid and others process products, this paper describes a previous precipitation and direct methods for routine analysis of thorium and uranium isotopes by ICP-MS. In all samples, {sup 230}Th, {sup 232}Th and {sup 238}U were directly determined after dilution, except {sup 230}Th in phosphoric acid loaded with uranium sample, which to overcome equipment contamination effect, was determined after its separation by oxalate precipitation using lanthanum as a carrier. The results obtained by the proposed method by ICP-MS, were in good agreement when compared to alpha spectrometry for {sup 230}Th, and ICP-OES and spectrophotometry with arsenazo III for elementary uranium and thorium determinations. (author)

  7. Determination of 235U/238U Ratio on Urine by ICP-MS

    Energy Technology Data Exchange (ETDEWEB)

    Collins, L; Gobaleza, A; Langston, R; Radev, R; Than, C; Wong, C; Wood-Zika, A

    2011-10-19

    LLNL Internal Dosimetry Program - The new procedure satisfies the requirement to determine {sup 235}U/{sup 238}U ratio in bioassay urine samples. MDA - The L{sub C} and MDA{sub 95} for {sup 235}U are well below the required detection limit of 0.00035 {mu}g/L. Turn around time - Analysis of 10 samples plus 2 QCs can be completed in one work day (8 hours).

  8. An Analysis of 178Pb to 238U Isotopes with the Universal and Yukawa Proximity Potentials

    Science.gov (United States)

    Javadimanesh, E.; Hassanabadi, H.; Zarrinkamar, S.

    2013-07-01

    The alpha particle preformation and the penetration probability by the Yukawa proximity potential in the even-even nuclei from 178Pb to 238U are studied. Using the experimental values of the alpha decay half-lives and the decay energies, we extract the preformation factors and the penetration probabilities. We also calculate the assault frequencies and the decay constants. The obtained results are motivating.

  9. Measurement of neutron inelastic scattering cross section of {sup 238}U

    Energy Technology Data Exchange (ETDEWEB)

    Miura, Takako; Baba, Mamoru; Ibaraki, Masanobu; Sanami, Toshiya; Win, Than; Hirasawa, Yoshitaka; Matsuyama, Shigeo; Hirakawa, Naohiro [Tohoku Univ., Sendai (Japan)

    1998-03-01

    Neutron scattering from the 0{sup +}, 2{sup +} (1-st) and 4{sup +} (2nd) levels of {sup 238}U was measured for incident energies between 0.4 and 0.85 MeV at the Tohoku University 4.5 MV Dynamitron facility, using the time-of-flight (TOF) method with monoenergetic pulsed neutrons by the {sup 7}Li(p,n) reaction. The results are presented in comparison with other experimental data and evaluated data. (author)

  10. Measurement of Prompt Fission Neutron Spectrum of 238U at 2.8 MeV

    Institute of Scientific and Technical Information of China (English)

    HUANG; Han-xiong; RUAN; Xi-chao; REN; Jie; LI; Guang-wu; LUAN; Guang-yuan

    2015-01-01

    The prompt fission neutron spectrum(PFNS,Fig.1)of 238U was measured at 2.8MeV incident neutron energy by using the Cockcroft&Walton accelerator in China Institute of Atomic Energy(CIAE).The effect-to-background ratio was improved by increasing the amount of sample mass and adding an appropriate shielding.The final uncertainty of neutron energy spectrum is less than 20%below 10MeV region at an bin size

  11. Solubility of 238U radionuclide from various types of soil in synthetic gastrointestinal fluids using "US in vitro" digestion method

    Science.gov (United States)

    Rashid, Nur Shahidah Abdul; Sarmani, Sukiman; Majid, Amran Ab.; Mohamed, Faizal; Siong, Khoo Kok

    2015-04-01

    238U radionuclide is a naturally occuring radioactive material that can be found in soil. In this study, the solubility of 238U radionuclide obtained from various types of soil in synthetic gastrointestinal fluids was analysed by "US P in vitro" digestion method. The synthetic gastrointestinal fluids were added to the samples with well-ordered, mixed throughly and incubated according to the human physiology digestive system. The concentration of 238U radionuclide in the solutions extracted from the soil was measured using Induced Coupling Plasma Mass Spectrometer (ICP-MS). The concentration of 238U radionuclide from the soil samples in synthetic gastrointestinal fluids showed different values due to different homogenity of soil types and chemical reaction of 238U radionuclide. In general, the solubility of 238U radionuclide in gastric fluid was higher (0.050 - 0.209 ppm) than gastrointestinal fluids (0.024 - 0.050 ppm). It could be concluded that the US P in vitro digestion method is practicle for estimating the solubility of 238U radionuclide from soil materials and could be useful for monitoring and risk assessment purposes applying to environmental, health and contaminated soil samples.

  12. Studies of positron electron pair production in {sup 238}U + {sup 232}Th

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, I.; Back, B.B.; Betts, R.R. [and others

    1995-08-01

    Following the non-observation of sharp sum-energy lines in our earlier {sup 238}U + {sup 181}Ta measurements, it was decided to pursue measurements of the {sup 238}U + {sup 232}Th system which, in the previously published work, showed the most striking evidence for near-equal-energy back-to-back pairs leading to sharp sum-energy lines. Following the refurbishing of the APEX silicon arrays and extensive tests of the rotating target wheel assembly, a major positron run took place in November 1994. Rolled 1-mg/cm{sub 2} {sup 232}Th targets were bombarded with 5.95-MeV/u {sup 238}U. The target rotation allowed up to 2 pnA of beam to be used without serious deterioration of the targets. Over 300,000 pairs were accumulated, representing an order-of-magnitude improvement in statistics over the previously published results. Preliminary analysis shows no evidence for the sharp lines at a cross section level orders of magnitude below those previously reported. The analysis of these data is currently being completed in preparation for publication.

  13. Initial Design Calculations for a Detection System that will Observe Resonant Excitation of the 680 keV state in 238U

    Energy Technology Data Exchange (ETDEWEB)

    Pruet, J; Hagmann, C

    2007-01-26

    We present calculations and design considerations for a detection system that could be used to observe nuclear resonance fluorescence in {sup 238}U. This is intended as part of an experiment in which a nearly monochromatic beam of light incident on a thin foil of natural uranium resonantly populates the state at 680 keV in {sup 238}U. The beam of light is generated via Compton upscattering of laser light incident on a beam of relativistic electrons. This light source has excellent energy and angular resolution. In the current design study we suppose photons emitted following de-excitation of excited nuclei to be observed by a segmented array of BGO crystals. Monte Carlo calculations are used to inform estimates for the design and performance of this detector system. We find that each detector in this array should be shielded by about 2 cm of lead. The signal to background ratio for each of the BGO crystals is larger than ten. The probability that a single detector observes a resonant photon during a single pulse of the light source is near unity.

  14. Uranium and radium in groundwater and surface water samples in Morocco

    Science.gov (United States)

    Hakam, O. K.; Choukri, A.; Moutia, Z.; Chouak, A.; Cherkaoui, R.; Reyss, J.-L.; Lferde, M.

    2001-06-01

    Activities and activity ratios of uranium and radium isotopes ( 234U, 238U, 226Ra, 228Ra, 234U/ 238U, 226Ra/ 238U, 228Ra/ 226Ra) have been determined for 15 wells, 14 hot springs, 7 cold springs and 11 rivers. Activities of the radium isotopes were measured by ultra gamma spectrometry using a low background and high efficiency well type germanium detector whereas those of uranium were counted in an alpha spectrometer. The minimal, maximal and average values are reported here for each water source. The obtained results show that, unlike well waters, the thermal spring waters present relatively low 238U activities and elevated 226Ra activities and 234U/ 238U activity ratios. Uranium and radium activities are similar to those published for other non polluting regions of the world.

  15. Determination of 238 U,226 Ra and the Calculation of Equilibrium Coefficient in Rock of Gangdise Tectonic Belt,Tibet%西藏冈底斯构造带岩(矿)石中238U 、226Ra测定及铀镭平衡系数计算

    Institute of Scientific and Technical Information of China (English)

    齐玲

    2015-01-01

    通过对西藏冈底斯构造带岩矿石中铀、镭测定结果的初步研究发现,铀矿(化)体中铀、镭平衡系数趋于1,而区内铀含量较低的水系沉积物、花岗岩、酸性火山岩等显示较强的偏镭特征。%The Gangdise tectonic belt is an important part of the Tethyan tectonic domain ,preliminary study on the dctermination result of 238 U and 226 Ra in the rocks and ores from the belt found that equilib‐rium coefficient of the uranium‐radium tends to 1 in uranium mineralized bodies , but low uranium content rock of river sediments , granite and acid volcanic is characterized by rich radium .

  16. Monte Carlo and deterministic simulations of activation ratio experiments for 238U(n,f), 238U(n,g) and 238U(n,2n) in the Big Ten benchmark critical assembly

    Energy Technology Data Exchange (ETDEWEB)

    Descalle, M; Clouse, C; Pruet, J

    2009-07-28

    The authors have compared calculations of critical assembly activation ratios using 3 different Monte Carlo codes and one deterministic code. There is excellent agreement. Discrepancies between the different Monte Carlo codes are the 1-2% level. Notably, the deterministic calculations with 87 groups are also in good agreement with the continuous energy Monte Carlo results. The three codes underestimate the {sup 238}U(n,f) reaction, suggesting that there is room for improvement in the evaluation, or in the evaluations of other reactions influencing the spectrum in BigTen. Until statistical uncertainties are implemented in Mercury, they strongly advise long runs to guarantee sufficient convergence of the flux at high energies, and they strongly encourage comparing Mercury results to a well-developed and documented code such as MCNP5 and/or COG. It may be that ENDL2008 will be available for use in COG within a year. Finally, it may be worthwhile to add a 'standard' reaction rate tally similar to those implemented in COG and MCNP5, if the goal is to expand the central fission and activation ratios simulations to include isotopes that are not part of the specifications for the assembly material composition.

  17. Generation of 238U Covariance Matrices by Using the Integral Data Assimilation Technique of the CONRAD Code

    Directory of Open Access Journals (Sweden)

    Privas E.

    2016-01-01

    Full Text Available A new IAEA Coordinated Research Project (CRP aims to test, validate and improve the IRDF library. Among the isotopes of interest, the modelisation of the 238U capture and fission cross sections represents a challenging task. A new description of the 238U neutrons induced reactions in the fast energy range is within progress in the frame of an IAEA evaluation consortium. The Nuclear Data group of Cadarache participates in this effort utilizing the 238U spectral indices measurements and Post Irradiated Experiments (PIE carried out in the fast reactors MASURCA (CEA Cadarache and PHENIX (CEA Marcoule. Such a collection of experimental results provides reliable integral information on the (n,γ and (n,f cross sections. This paper presents the Integral Data Assimilation (IDA technique of the CONRAD code used to propagate the uncertainties of the integral data on the 238U cross sections of interest for dosimetry applications.

  18. Background reduction in {sup 236}U/{sup 238}U measurements

    Energy Technology Data Exchange (ETDEWEB)

    Buompane, Raffaele [CIRCE, Dipartimento di Matematica e Fisica, Seconda Università degli Studi di Napoli and INNOVA, Caserta (Italy); INFN sezione di Napoli (Italy); De Cesare, Mario [Department of Nuclear Physics, The Australian National University, ACT 2601 (Australia); De Cesare, Nicola [CIRCE, Dipartimento di Matematica e Fisica, Seconda Università degli Studi di Napoli and INNOVA, Caserta (Italy); INFN sezione di Napoli (Italy); Di Leva, Antonino [INFN sezione di Napoli (Italy); Dipartimento di Fisica, Università di Napoli “Federico II” (Italy); D’Onofrio, Antonio [CIRCE, Dipartimento di Matematica e Fisica, Seconda Università degli Studi di Napoli and INNOVA, Caserta (Italy); INFN sezione di Napoli (Italy); Fifield, L. Keith; Fröhlich, Michaela [Department of Nuclear Physics, The Australian National University, ACT 2601 (Australia); Gialanella, Lucio; Marzaioli, Fabio; Sabbarese, Carlo; Terrasi, Filippo [CIRCE, Dipartimento di Matematica e Fisica, Seconda Università degli Studi di Napoli and INNOVA, Caserta (Italy); INFN sezione di Napoli (Italy); Tims, Stephen; Wallner, Anton [Department of Nuclear Physics, The Australian National University, ACT 2601 (Australia)

    2015-10-15

    The measurements of actinide isotopic ratios, in particular {sup 236}U/{sup 238}U, in environmental samples requires high sensitivity. In particular, special effort must be devoted to the suppression of interfering nuclides, such as {sup 235,238}U, when measuring {sup 236}U. At the AMS facility of CIRCE, isotopic ratios down to ∼10{sup −10} are currently measured using a gas E − ΔE detector. In order to push this limit lower towards natural levels, a time-of-flight system is used, featuring a micro-channel plate start detector and a Si stop detector. As the mass resolution of the latter is limited by the layout, an attempt to reduce the abundant isotope interference by other means has been undertaken. In this study, we report preliminary results on the characterization of the presence of molecular interferences when using UO{sup −}, UC{sup −} and UC{sub 2}{sup −} as injected molecular ions. In particular the possibility to stabilize the current yield from carbide cathodes has been investigated: it was found that the best cathode preparation procedure is obtained pressing U salts baked at 800 °C mixed with graphite and Al powder. Moreover, the {sup 238}U background in {sup 236}U measurements is strongly reduced injecting UC{sup −} ions, as verified using a time-of-flight detection system. On the other hand, {sup 235}U interference is larger with respect to UO{sup −} injection, but this increase is smaller than expected on the basis of abundances of {sup 13}C and {sup 17}O in UC and UC{sub 2} molecules on one side and UO, on the other.

  19. Potential Energy Surfaces of the Even-Even 230-238 U Isotopes

    Directory of Open Access Journals (Sweden)

    Diab S. M.

    2008-07-01

    Full Text Available Nuclear structure of 230 - 238 U isotopes have been studied in the frame work of the in- teracting boson approximation model (IBM-I. The contour plot of the potential energy surfaces, V ( ; , shows that all nuclei are deformed and have rotational char- acters, SU (3 . Levels energy spectra belonging to the gsb , , bands, electromagnetic transition rates B ( E 1 and B ( E 2 , quadrupole moment Q 0 , deformation parameterare 2 and the strength of the electric monopole transitions X ( E 0 =E 2 are calculated. The calculated values are compared with the available theoretical and experimental data and show reasonable agreement.

  20. CREATING THE KULTUK POLYGON FOR EARTHQUAKE PREDICTION: VARIATIONS OF (234U/238U AND 87SR/86SR IN GROUNDWATER FROM ACTIVE FAULTS AT THE WESTERN SHORE OF LAKE BAIKAL

    Directory of Open Access Journals (Sweden)

    S. V. Rasskazov

    2015-12-01

    Full Text Available Introduction. Determinations of (234U/238U in groundwater samples are used for monitoring current deformations in active faults (parentheses denote activity ratio units. The cyclic equilibrium of activity ratio 234U/238U≈≈(234U/238U≈γ≈1 corresponds to the atomic ratio ≈5.47×10–5. This parameter may vary due to higher contents of 234U nuclide in groundwater as a result of rock deformation. This effect discovered by P.I. Chalov and V.V. Cherdyntsev was described in [Cherdyntsev, 1969, 1973; Chalov, 1975; Chalov et al., 1990; Faure, 1989]. In 1970s and 1980s, only quite laborious methods were available for measuring uranium isotopic ratios. Today it is possible to determine concentrations and isotopic ration of uranium by express analytical techniques using inductively coupled plasma mass spectrometry (ICP‐MS [Halicz et al., 2000; Shen et al., 2002; Cizdziel et al., 2005; Chebykin et al., 2007]. Sets of samples canbe efficiently analysed by ICP‐MS, and regularly collected uranium isotope values can be systematized at a new quality level for the purposes of earthquake prediction. In this study of (234U/238U in groundwater at the Kultuk polygon, we selected stations of the highest sensitivity, which can ensure proper monitoring of the tectonic activity of the Obruchev and Main Sayan faults. These two faults that limit the Sharyzhalgai block of the crystalline basement of the Siberian craton in the south are conjugated in the territory of the Kultuk polygon (Fig 1. Forty sets of samples taken from 27 June 2012 to 28 January 2014 were analysed, and data on 170 samples are discussed in this paper.Methods. Isotope compositions of uranium and strontium were determined by methods described in [Chebykin et al., 2007; Pin et al., 1992] with modifications. Analyses of uranium by ISP‐MS technique were performed using an Agilent 7500ce quadrapole mass spectrometer of the Ultramicroanalysis Collective Use Centre; analyses of

  1. Intermediate structure in the /sup 238/U neutron capture cross section

    Energy Technology Data Exchange (ETDEWEB)

    Perez, R.B.; de Saussure, G.

    1975-10-01

    Recent measurements of the /sup 238/U neutron capture cross section show large fluctuations in the unresolved resonance region. To test whether or not the observed long-range fluctuation of the neutron capture represent departures from the compound nuclear model, the Wald-Wolfowitz runs and correlation tests were applied to the /sup 238/U neutron capture data obtained at ORELA. The Wald-Wolfowitz runs test deals with the statistic, R, which is the number of unbroken sequences of data points above or below a given reference line. This statistic is to be compared with the expected value of runs E(R) +- sigma(R) arising from randomly distributed data. In the correlation test we have computed the first serial correlation coefficient of the data as well as its expected value and variance for a set of random data. In both tests one computes the probability, P, for the given statistical entity to depart from its expected value by more than epsilon standard deviations. Both tests confirm the presence of intermediate structure between 5 and 100 keV. The range of the structure far exceeds the width of the experimental resolution and level widths. 3 tables, 2 figures. (auth)

  2. Natural Activities of 238U, 232Th and 40K in Manganese Ore

    Directory of Open Access Journals (Sweden)

    H. A. Abel-Ghany

    2010-01-01

    Full Text Available Problem statement: Manganese ore is widely used in much industries. Such as ore contain natural radioactive nuclides at various concentrations. If this ore contain high concentrations of natural radioactive nuclides, workers handling them might be exposed to significant levels of radiation. Therefore it is important to determine the radioactive nuclides in this ore. Approach: The natural radionuclides (238U, 232Th and 40K contents of Manganese ore samples collected by Siani Manganese Company in Egypt-Cairo have been determined by low background spectroscopy using hyper-pure germanium (HPGe detector. Results: The mean activities due to the three radionuclides (238U, 232Th and40K were found to be 3543±106, 222±6.6 and 3483±104 Bqkg-1, respectively. The absorbed dose rate due to the natural radioactivity in samples under investigation ranged from 1522±45-1796±53 nGyh-1. The radium equivalent activity varied from 3807±114-4446±133 Bqkg-1. The representative external hazard index values for the corresponding samples are also estimated. Conclusion: The results of this assessment obtained by the gamma-ray spectroscopic analysis, have indicated that the levels of natural radioactivity were higher than the international recommended limits.

  3. The low-energy dipole structure of 232Th , 236U and 238U actinide nuclei

    Science.gov (United States)

    Kuliev, A. A.; Guliyev, E.; Ertugral, F.; Özkan, S.

    2010-03-01

    In this study, ensuremath I^{π} = 1+ and ensuremath I^{π} = 1- dipole mode excitations are systematically investigated within the rotational and translational + Galilean invariant quasiparticle random-phase approximation for 232Th , 236U , and 238U actinide nuclei. It is shown that the investigated nuclei reach a B( M1) strength structure, which corresponds to the scissors mode. The calculated mean excitation energies as well as the summed B( M1) value of the scissors mode excitations are consistent with the available experimental data. The results of calculations indicate large differences to the rare-earth nuclei as is the case for the experiment: a doubling of the observed dipole strengths and a shift of the energy centroid to the lower energies by about 800keV. The calculations indicate the presence of a few prominent negative-parity ensuremath K^{π} = 1- states in the 2.0-4.0MeV energy interval. The occurrence of the negative-parity dipole states with the rather high B( E1) value less than 4MeV shows the necessity of explicit parity measurements for the correct determination of the scissors mode strength in 232Th , 236U , and 238U isotopes.

  4. Analysis of the {sup 238}U resonance parameters using random-matrix theory

    Energy Technology Data Exchange (ETDEWEB)

    Courcelle, A. [CEA Cadarache, 13 - Saint Paul lez Durance (France); Derrien, H.; Leal, L.C.; Larson, N.M. [Oak Ridge National Laboratory, Oak Ridge, TN (United States)

    2005-07-01

    Random-matrix theories (RMTs) provide valuable statistical tools to analyze neutron-resonance data. The predictive power of the random-matrix theories, which do not contain any adjustable parameters, is striking, and the application is rather simple and fast. A new evaluation of {sup 238}U resonance parameters has recently been performed at the Oak Ridge National Laboratory; the objective of this paper is to illustrate the use of RMT in the field of resonance-parameter evaluation with the newly evaluated {sup 239}U energy levels and widths. Several statistics were computed using the s-wave resonances up to 20 keV and compared to the Gaussian Orthogonal Ensemble predictions. It is shown that a good agreement is observed between RMT and the experimental data up to 2.5 keV. The F-Dyson statistic was especially investigated because of its claimed ability to detect locally missed and spurious levels in the sample (p-resonances contamination or unresolved multiplets). As expected, the entire set of evaluated {sup 238}U s-wave resonances up to 20 keV disagrees significantly with the theory. There are two reasons for this: First, it is difficult to distinguish s- and p-wave resonances in the analysis. Secondly, especially above 10 keV, it is impossible to determine reliable resonance energies from the available experimental data. It is concluded that the use of RMT can help nuclear data specialists to improve their evaluations in the resonance range. (authors)

  5. The dependence of cumulative 238U(n,f) fission yield on incident-neutron energy

    Institute of Scientific and Technical Information of China (English)

    ZHENG Na; ZHONG Chunlai; MA Liyong; CHEN Zhongjing; LI Xiangqing; LIU Tingjin; CHEN Jinxiang; FAN Tieshuan

    2009-01-01

    This work is aim at studying the dependence of fission yields on incident neutron energy,so as to produce evaluated yield sets of the energy dependence.Experimental data at different neutron energies for gas fission products 85m,87,88Kr and 138Xe resulting from the 238U(n,f) reaction are processed using codes AVERAGE for weighed average and ZOTT for simultaneous evaluation.Energy dependence of the cumulative fission product yields on the incident neutron is presented.The evaluated curve of product yield is compared with the results calculated by the TALYS-0.64 code.The present evaluation is consistent with other main libraries in error permission.The fit curve of 87,88Kr can be recommended to predict the unmeasured fission yields.Comparisons of the evaluated energy dependence curves with theoretical calculated results show that the predictions using purely theoretical model for the fission process are not sufficiently accurate and reliable for the calculations of the cumulative fission yields for the 238U(n,f).

  6. Natural activities of {sup 238}U, {sup 232}Th and {sup 40}K in building materials

    Energy Technology Data Exchange (ETDEWEB)

    Ibrahim, N. [Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    1999-05-01

    Seven kinds of building materials were analysed for {sup 238}U, {sup 232}Th and {sup 40}K using a direct {gamma}-counting method. The activity concentrations measured for {sup 238}U (30-448 Bq kg{sup -1}) and {sup 40}K (328-7541 Bq kg{sup -1}) were greater than the world average activity for soil (25 and 370 Bq kg{sup -1}, respectively) for all building materials analysed, while the activity concentrations of {sup 232}Th were found to exceed the average of 25 Bq kg{sup -1} (soil) for red-clay brick (51 Bq kg{sup -1}) and ceiling asbestos sheet materials (162 Bq kg{sup -1}). The calculated Ra equivalent activities (Ra{sub eq}) for all materials are higher than the world average value for soil (89 Bq kg{sup -1}). For red-clay brick and ceiling asbestos, the Ra{sub eq} values are found to exceed the limit of 370 Bq kg{sup -1}, equivalent to a {gamma}-dose of 1.5 mSv yr{sup -1}. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  7. Photofission product yields of 238U and 239Pu with 22-MeV bremsstrahlung

    Science.gov (United States)

    Wen, Xianfei; Yang, Haori

    2016-06-01

    In homeland security and nuclear safeguards applications, non-destructive techniques to identify and quantify special nuclear materials are in great demand. Although nuclear materials naturally emit characteristic radiation (e.g. neutrons, γ-rays), their intensity and energy are normally low. Furthermore, such radiation could be intentionally shielded with ease or buried in high-level background. Active interrogation techniques based on photofission have been identified as effective assay approaches to address this issue. In designing such assay systems, nuclear data, like photofission product yields, plays a crucial role. Although fission yields for neutron-induced reactions have been well studied and readily available in various nuclear databases, data on photofission product yields is rather scarce. This poses a great challenge to the application of photofission techniques. In this work, short-lived high-energy delayed γ-rays from photofission of 238U were measured in between linac pulses. In addition, a list-mode system was developed to measure relatively long-lived delayed γ-rays from photofission of 238U and 239Pu after the irradiation. Time and energy information of each γ-ray event were simultaneously recorded by this system. Cumulative photofission product yields were then determined using the measured delayed γ-ray spectra.

  8. {sup 90}Sr, {sup 238}U, {sup 234}U, {sup 137}Cs, {sup 40}K and {sup 239/240}Pu in Emmental type cheese produced in different regions of Western Europe

    Energy Technology Data Exchange (ETDEWEB)

    Froidevaux, P. E-mail: pascal.froidevaux@inst.hospvd.ch; Geering, J.-J.; Pillonel, L.; Bosset, J.-O.; Valley, J.-F

    2004-07-01

    A method is presented for the determination of {sup 90}Sr and uranium in Emmental type cheese collected in dairy plants from different European countries. Results display a significant correlation (r=0.708, Student t-test=6.02) between the {sup 90}Sr content of the cheese and the altitude of grazing. The highest {sup 90}Sr activity is 1.13 Bq kg{sup -1} of cheese and the lowest is 0.29 Bq kg{sup -1}. Uranium activity is very low with a highest {sup 238}U value of 27 mBq kg{sup -1}. In addition, {sup 234}U/{sup 238}U ratio shows a large enrichment in {sup 234}U for every location. Without any significant indication of the geographic origin of the cheese, this enrichment is believed to be due to the geological features of the pasture, soil and underground water. These results tend to prove that the contamination of milk by uranium originates principally from the water that the cows drink instead of the forage. This finding may have a great importance in models dealing with dairy food contamination by radionuclides following a nuclear accident. Also, the {sup 90}Sr content and to a lesser extent the {sup 234}U/{sup 238}U ratio could be used to trace the authenticity of the origin of the cheese. {sup 137}Cs activity is lower than the detection limit of 0.1 Bq kg{sup -1} in all the samples collected (n=20). Based on natural {sup 40}K activity in cheese (15-21 Bq kg{sup -1}), the decontamination factor for the alkaline cations from milk to cheese is about 20. Plutonium activity stays below the detection limit of 0.3 mBq kg{sup -1}.

  9. Measurement of the 238U neutron-capture cross section and gamma-emission spectra from 10 eV to 100 keV using the DANCE detector at LANSCE

    Energy Technology Data Exchange (ETDEWEB)

    Ullmann, John L [Los Alamos National Laboratory; Couture, A J [Los Alamos National Laboratory; Keksis, A L [Los Alamos National Laboratory; Vieira, D J [Los Alamos National Laboratory; O' Donnell, J M [Los Alamos National Laboratory; Jandel, M [Los Alamos National Laboratory; Haight, R C [Los Alamos National Laboratory; Rundberg, R S [Los Alamos National Laboratory; Kawano, T [Los Alamos National Laboratory; Chyzh, A [NORTH CAROLINA STATE UNIV; Baramsai, B [NORTH CAROLINA STATE UNIV; Wu, C Y [LLNL; Mitchell, G E [NORTH CAROLINA STATE UNIV; Becker, J A [LLNL; Krticka, M [CHARLES UNIV

    2010-01-01

    A careful new measurement of the {sup 238}U(n,{gamma}) cross section from 10 eV to 100 keV has been made using the DANCE detector at LANSCE. DANCE is a 4{pi} calorimetric scintillator array consisting of 160 BaF{sub 2} crystals. Measurements were made on a 48 mg/cm{sup 2} depleted uranium target. The cross sections are in general good agreement with previous measurements. The gamma-ray emission spectra, as a function of gamma multiplicity, were also measured and compared to model calculations.

  10. Measurements of yields of fission products in the reaction of {sup 238}U with high-energy p, d and n beams

    Energy Technology Data Exchange (ETDEWEB)

    Nolen, J.A.; Ahmad, I.; Back, B.B. [and others

    1995-08-01

    An experiment was performed at the Michigan State University cyclotron to determine the yields of neutron-rich fission products in the reaction of {sup 238}U with 100-MeV neutrons, 200-MeV deuterons and 200-MeV protons. Several 1-mm-thick {sup 238}U foils were irradiated for 100-second intervals sequentially for each configuration and the ten spectra were added for higher statistics. The three successive spectra, each for a 40 s period, were accumulated for each sample. Ten foils were irradiated. Successive spectra allowed us to determine approximate half-lives of the gamma peaks. Several arrangements, which were similar to the setup we plan to use in our radioactive beam proposal, were used for the production of fission products. For the high-energy neutron irradiation, U foils were placed after a 5-inch-long, 1-inch-diameter Be cylinder which stopped the 200-MeV deuteron beam generating 100-MeV neutrons. Arrangements for deuteron irradiation included direct irradiation of U foils, placing U foils after different lengths of (0.5 inch, 1.0 inch and 1.5 inch) 2-inch diameter U cylinder. Since the deuteron range in uranium is 17 mm, some of the irradiations were due to the secondary neutrons from the deuteron-induced fission of U. Similar arrangements were also used for the 200-MeV proton irradiation of the {sup 238}U foils. In all cases, several neutron-rich fission products were identified and their yields determined. In particular, we were able to observe Sn in all the runs and determine its yield. The data show that with our proposed radioactive device we will be able to produce more than 10{sup 12} {sup 132}Sn atoms per second in the target. Assuming an overall efficiency of 1 %, we will be able to deliver one particle nanoampere of {sup 132}Sn beam at a target location. Detailed analysis of the {gamma}-ray spectra is in progress.

  11. Separation and quantification of {sup 238}U, {sup 232}Th and rare earths in monazite samples by ion chromatography coupled with on-line flow scintillation detector

    Energy Technology Data Exchange (ETDEWEB)

    Borai, E.H.; Mady, A.S

    2002-10-01

    An alternative procedure has been described for efficient separation and quantitative determination of uranium (U), thorium (Th) and rare earth elements (REEs) in monazite mineral by high performance ion chromatographic system (IC). Different variables affecting the distribution coefficient, the retention and hence separation efficiency such as eluent flow rate and concentrations of HCl and ammonium sulfate (NH{sub 4}){sub 2}SO{sub 4} containing the mobile phase were studied. The developed separation protocol of U, Th and REEs was optimized using an Ion Pac CS5 separation column followed by post-column derivatization reaction with Arsenaso III and UV-VIS spectrophotometeric detection. Comparative evaluation of U, Th and REEs concentration in monazite mineral was demonstrated using two different on-line detection modes including flow through cell scintillation detector (FSD) and UV-VIS spectrophotometer. Response of the FSD was found to be linear over the full range of activities investigated (4-100 Bq). The lower limits of detection (LLD) for the investigated radionuclides were 3.0{+-}0.1 Bq for {sup 238}U and 6.0{+-}0.1 Bq for {sup 232}Th. The detection of {sup 238}U and {sup 232}Th by FSD shows good agreement with the corresponding determination by UV-VIS spectrophotometer. The content of ThO{sub 2} and U{sub 3}O{sub 8} in monazite sample were found to be 4.7{+-}0.1% and 0.42{+-}0.04% using UV-VIS detector and 4.3{+-}0.1% and 0.45{+-}0.1% using FSD, respectively.

  12. Symmetric splitting for the system 32S+238U at energies near and below the barrier

    Science.gov (United States)

    Freifelder, R.; Braun-Munzinger, P.; Deyoung, P.; Schicker, R.; Sen, S.; Stachel, J.

    1987-06-01

    The total capture cross section for the system 32S+238U has been measured at energies from 0.93 to 1.08 times the s-wave interaction barrier by detecting coincident fission fragments following full momentum transfer reactions. The subbarrier cross section cannot be reproduced by a one-dimensional barrier penetration model. Using a quantum mechanical coupled channels model, good agreement is obtained. The measured angular distributions of fission fragments were compared to the predictions of saddle and scission point transition state theory. Saddle point transition state model calculations fail to reproduce the data, while scission point transition state calculations are in agreement with their qualitative trend. Evidence for nonequilibrium processes is presented.

  13. Studies of positron electron pair production in {sup 238}U + {sup 181}Ta

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, I.; Back, B.B.; Betts, R.R. [and others

    1995-08-01

    Following the completion of APEX in late 1993, a two-week run on the {sup 238}U + {sup 181}Ta system at 6.1 and 6.3 MeV/u with 1 mg/cm{sup 2} targets provided, for the first time, data in which the expected sharp sum-energy lines should appear. Data from previous experiments show evidence for sharp sum-energy lines at 625, 748 and 805 keV, observed at bombarding energies from 5.9 to 6.3 MeV/u. The 625- and 809-keV lines display the characteristics of equal-energy back-to-back emission whereas the 748-keV line shows a rather different behavior. In our measurements, average beam currents of 2-3 pnA from the ATLAS accelerator were used to bombard 1-mg/cm{sup 2} rolled {sup 181}Ta targets, the energy loss in which corresponds to the ranges of bombarding energies over which the sharp sum-energy lines were previously reported. A run at 5.95 MeV/u for {sup 238}U + {sup 181}Ta followed in May 1994. These data were analyzed extensively. Sum-energy spectra measured in coincidence with scattered ions in the range 20{degrees} < {theta} < 68{degrees}. No evidence is found for the sharp sum-energy lines reported previously and, depending on the scenario assumed for the production mechanism and kinematics of the pairs, upper limits on cross sections at the 90% confidence limit range from 10-100 times smaller than the values that can be deduced from the earlier reports. We are in the process of refining the data analysis and simulations of the apparatus in order to finalize these numbers for publication.

  14. Fluxes of 238U decay series radionuclides in a dicalcium phosphate industrial plant.

    Science.gov (United States)

    Casacuberta, N; Masqué, P; Garcia-Orellana, J

    2011-06-15

    The production of dicalcium phosphate (DCP) is part of the phosphate industry, which has been recently included in the positive list of the NORM industries defined in the revised version of the EU-BSS (Euratom 29/96). The objective of the present work is to study specific concentrations and fluxes of (238,234)U, (230)Th, (226)Ra, (210)Pb and (210)Po at the different stages of the DCP production. Results showed highest activities of (238)U and (210)Pb were found in DCP (1500-2000 Bq kg(-1)); (230)Th and (210)Po were released together with the sludges (1600-2000 Bq kg(-1)) and (226)Ra presented particularly high activities in water (48 × 10(3) Bq m(-3)) and in the reactor scales (115 × 10(3) Bq kg(-1)). Fluxes of radionuclides showed that (238)U outflows were equally distributed between sludges (16 × 10(3) kBq h(-1)) and dicalcium phosphate (20 × 10(3) kBq h(-1)); (230)Th and (210)Po were almost entirely released in the sludges (30 × 10(3)kBq h(-1)) and the greatest (210)Pb outflow was the DCP current (25 × 10(3) kBq h(-1)). (226)Ra was mainly discharged through the water effluent (12 × 10(3) kBq h(-1)). This work highlights the importance of studying the industrial processes involving NORM, as minor changes in the production steps lead to different radionuclide distribution in the process.

  15. Fluxes of {sup 238}U decay series radionuclides in a dicalcium phosphate industrial plant

    Energy Technology Data Exchange (ETDEWEB)

    Casacuberta, N., E-mail: Nuria.Casacuberta@uab.es [Institut de Ciencia i Tecnologia Ambientals - Departament de Fisica, Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain); Masque, P.; Garcia-Orellana, J. [Institut de Ciencia i Tecnologia Ambientals - Departament de Fisica, Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain)

    2011-06-15

    The production of dicalcium phosphate (DCP) is part of the phosphate industry, which has been recently included in the positive list of the NORM industries defined in the revised version of the EU-BSS (Euratom 29/96). The objective of the present work is to study specific concentrations and fluxes of {sup 238,234}U, {sup 230}Th, {sup 226}Ra, {sup 210}Pb and {sup 210}Po at the different stages of the DCP production. Results showed highest activities of {sup 238}U and {sup 210}Pb were found in DCP (1500-2000 Bq kg{sup -1}); {sup 230}Th and {sup 210}Po were released together with the sludges (1600-2000 Bq kg{sup -1}) and {sup 226}Ra presented particularly high activities in water (48 x 10{sup 3} Bq m{sup -3}) and in the reactor scales (115 x 10{sup 3} Bq kg{sup -1}). Fluxes of radionuclides showed that {sup 238}U outflows were equally distributed between sludges (16 x 10{sup 3} kBq h{sup -1}) and dicalcium phosphate (20 x 10{sup 3} kBq h{sup -1}); {sup 230}Th and {sup 210}Po were almost entirely released in the sludges (30 x 10{sup 3} kBq h{sup -1}) and the greatest {sup 210}Pb outflow was the DCP current (25 x 10{sup 3} kBq h{sup -1}). {sup 226}Ra was mainly discharged through the water effluent (12 x 10{sup 3} kBq h{sup -1}). This work highlights the importance of studying the industrial processes involving NORM, as minor changes in the production steps lead to different radionuclide distribution in the process.

  16. Neutron Capture Cross Sections and Gamma Emission Spectra from Neutron Capture on 234,236,238U Measured with DANCE

    Science.gov (United States)

    Ullmann, J. L.; Mosby, S.; Bredeweg, T. A.; Couture, A. J.; Haight, R. C.; Jandel, M.; Kawano, T.; O'Donnell, J. M.; Rundberg, R. S.; Vieira, D. J.; Wilhelmy, J. B.; Wu, C.-Y.; Becker, J. A.; Chyzh, A.; Baramsai, B.; Mitchell, G. E.; Krticka, M.

    2014-05-01

    A new measurement of the 238U(n, γ) cross section using a thin 48 mg/cm2 target was made using the DANCE detector at LANSCE over the energy range from 10 eV to 500 keV. The results confirm earlier measurements. Measurements of the gamma-ray emission spectra were also made for 238U(n, γ) as well as 234,236U(n, γ). These measurements help to constrain the radiative strength function used in the cross-section calculations.

  17. Combined 238U/235U and Pb Isotopics of Planetary Core Material: The Absolute Age of the IVA Iron Muonionalusta

    Science.gov (United States)

    Brennecka, G. A.; Amelin, Y.; Kleine, T.

    2016-08-01

    We report a measured 238U/235U for the IVA iron Muonionalusta. This measured value requires an age correction of ~7 Myr to the previously published Pb-Pb age. This has major implications for our understanding of planetary core formation and cooling.

  18. Vertical flux of particulate organic carbon in the central South China Sea estimated from 234Th-238U disequilibria

    Institute of Scientific and Technical Information of China (English)

    MA Hao; ZENG Zhi; HE Jianhua; CHEN Liqi; YIN Mingduan; ZENG Shi; ZENG Wenyi

    2008-01-01

    234Th-238u disequilibria were applied to examine the particle dynamics in the euphotic zone of the central South China Sea during the spring 2002 cruise. The particulate organic carbon (POC), 234Th (including both dissolved and particulate) and 238U in the water column at three stations were determined. The profiles of 234Th/238U activity ratio at the three stations all showed consistent 234Th deficit as compared to 238U in the upper 100 m water column. Based on the profiles of the dissolved and particulate 234Th and a steady state box model, the dissolved 234Th scavenging rates, the particulate 234Th removal rates and their resident times were quantified. It was found that the POC downward export fluxes out of the upper 100 m euphotic zone ranged from 9.40 to 14.78 mmol.m-2.d-1. The results from this study provide new information for our understanding of carbon biogeochemical cycle in the South China Sea.

  19. Mass yield distributions of fission products from photo-fission of {sup 238}U induced by 11.5-17.3 MeV bremsstrahlung

    Energy Technology Data Exchange (ETDEWEB)

    Naik, H.; Goswami, A. [Bhabha Atomic Research Centre, Radiochemistry Division, Mumbai (India); Carrel, Frederick; Laine, Frederic; Sari, Adrien [SAPHIR Facility, Gif-sur-Yvette (France); Kim, G.N. [Kyungpook National University, Department of Physics, Daegu (Korea, Republic of); Normand, S. [Laboratory of Sensors and Elctronics Architectures CEA, Gif-sur-Yvette (France)

    2013-07-15

    The yields of various fission products in the 11.5, 13.4, 15.0 and 17.3 MeV bremsstrahlung-induced fission of {sup 238}U have been determined by recoil catcher and an off-line {gamma}-ray spectrometric technique using the electron linac, SAPHIR at CEA, Saclay, France. The mass yield distributions were obtained from the fission product yields using charge-distribution corrections. The peak-to-valley (P/V) ratio, average light mass (left angle A{sub L} right angle) and heavy mass (left angle A{sub H} right angle) and average number of neutrons (left angle v right angle) in the bremsstrahlung-induced fission of {sup 238}U at different excitation energies were obtained from the mass yield data. From the present and literature data in the {sup 238}U ({gamma}, f) and {sup 238}U (n, f) reactions at various energies, the following observations were obtained: i) The mass yield distributions in the {sup 238}U ({gamma}, f) reaction at various energies of the present work are double-humped, similar to those of the {sup 238}U (n, f) reaction of comparable excitation energy. ii) The yields of fission products for A = 133-134, A = 138-140, and A = 143-144 and their complementary products in the {sup 238}U ({gamma}, f) reaction are higher than other fission products due to the nuclear structure effect. iii) The yields of fission products for A = 133-134 and their complementary products are slightly higher in the {sup 238}U ({gamma}, f) than in the {sup 238}U (n, f), whereas for A = 138-140 and 143-144 and their complementary products are comparable. iv) With excitation energy, the increase of yields of symmetric products and the decrease of the peak-to-valley (P/V ratio in the {sup 238}U ({gamma}, f) reaction is similar to the {sup 238}U (n, f) reaction. v) The increase of left angle v right angle with excitation energy is also similar between the {sup 238}U ({gamma}, f) and {sup 238}U (n, f) reactions. However, it is surprising to see that the left angle A{sub L} right angle and

  20. Mass yield distributions of fission products from photo-fission of 238U induced by 11.5-17.3 MeV bremsstrahlung

    Science.gov (United States)

    Naik, H.; Carrel, Frédérick; Kim, G. N.; Laine, Frédéric; Sari, Adrien; Normand, S.; Goswami, A.

    2013-07-01

    The yields of various fission products in the 11.5, 13.4, 15.0 and 17.3 MeV bremsstrahlung-induced fission of 238U have been determined by recoil catcher and an off-line γ-ray spectrometric technique using the electron linac, SAPHIR at CEA, Saclay, France. The mass yield distributions were obtained from the fission product yields using charge-distribution corrections. The peak-to-valley ( P/ V ratio, average light mass () and heavy mass () and average number of neutrons () in the bremsstrahlung-induced fission of 238U at different excitation energies were obtained from the mass yield data. From the present and literature data in the 238U ( γ, f ) and 238U ( n, f ) reactions at various energies, the following observations were obtained: i) The mass yield distributions in the 238U ( γ, f ) reaction at various energies of the present work are double-humped, similar to those of the 238U ( n, f ) reaction of comparable excitation energy. ii) The yields of fission products for A = 133-134, A = 138-140, and A = 143-144 and their complementary products in the 238U ( γ, f) reaction are higher than other fission products due to the nuclear structure effect. iii) The yields of fission products for A = 133-134 and their complementary products are slightly higher in the 238U ( γ, f ) than in the 238U ( n, f ) , whereas for A = 138-140 and 143-144 and their complementary products are comparable. iv) With excitation energy, the increase of yields of symmetric products and the decrease of the peak-to-valley ( P/ V ratio in the 238U ( γ, f) reaction is similar to the 238U ( n, f) reaction. v) The increase of with excitation energy is also similar between the 238U ( γ, f ) and 238U ( n, f) reactions. However, it is surprising to see that the and values with excitation energy behave entirely differently from the 238U ( γ, f ) and 238U ( n, f ) reactions.

  1. Correlation of the activity of the {sup 238} U in soil and {sup 222} Rn in domiciles, with the rocks of cities of the Estado de Chihuahua; Correlacion de la actividad del {sup 238} U en suelo y {sup 222} Rn en domicilios, con las rocas de ciudades del Estado de Chihuahua

    Energy Technology Data Exchange (ETDEWEB)

    Colmenero S, L.; Villalba, L.; Montero C, M.E. [Centro de Investigacion en Materiales Avanzados (CIMAV), Av. Miguel de Cervantes 120 C.P. 31109 Chihuahua (Mexico)]. e-mail: luis.colmenero@cimav.edu.mx

    2004-07-01

    The state of Chihuahua has numerous locations of uranium, being Pena Blanca the great and more important location of the country. Diverse rock types with important quantities of uranium are distributed by the whole state. The igneous extrusive acid rocks are those that have bigger quantity of uranium, like they are the rhyolites and dacites and these rocks are located in enough proportion by the whole state. Some of the main cities of the state are near to locations or uraniferous rocks, as Aldama, Nuevo Casas Grandes, Chihuahua, Jimenez and Bocoyna, other important cities are not near important locations. It was determined specific activity by gamma spectroscopy of the series of the {sup 238} U in soils and determination of the radon concentration in domiciles of the main cities of the state. They were found high specific activity values in soil in eight of the thirteen analyzed cities and important radon concentrations in three cities. It was found relationship among the specific activity in soil in near cities to uraniferous locations. (Author)

  2. Determination of {sup 234}U and {sup 238}U in seawater samples by alpha spectrometry after concentration of U(VI) onto hydrotalcite and co-precipitation with LaF{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Suc, N.V. [University of Technical Education Ho Chi Minh City (Viet Nam); Bich, T.T. [Center for Nuclear Techniques, Ho Chi Minh City (Viet Nam)

    2013-07-01

    This paper presents a simple and accurate method for determination of uranium isotopes ({sup 234}U and {sup 238}U) in seawater samples using alpha spectrometry. Uranium is pre-concentrated from seawater samples via adsorption on hydrotalcite at pH 6.5. The absorbent is dissolved into 50 ml of 8M HNO{sub 3}; then filtered through a Dowex-1 column. U(VI) in the elution solution is reduced to U(IV) using zinc metal in 4M solution of HCl and then co-precipitated with LaF{sub 3}. The chemical separation efficiency is found to be 97.12 {+-} 2.68%, eliminating the need of using {sup 232}U tracer in other published methods. This method is validated via comparison with results obtained using inductively coupled plasma mass spectrometry (ICP-MS) and neutron activation analysis (NAA) for three seawater samples. (orig.)

  3. 238U(n, γ reaction cross section measurement with C6D6 detectors at the n_TOF CERN facility.

    Directory of Open Access Journals (Sweden)

    Mingrone F.

    2014-03-01

    Full Text Available The radiative capture cross section of 238U is very important for the developing of new reactor technologies and the safety of existing ones. Here the preliminary results of the 238U(n,γ cross section measurement performed at n_TOF with C6D6 scintillation detectors are presented, paying particular attention to data reduction and background subtraction.

  4. 230Th/238U dating of hydrothermal sulfides from Duanqiao hydrothermal field, Southwest Indian Ridge

    Science.gov (United States)

    Yang, Weifang; Tao, Chunhui; Li, Huaiming; Liang, Jin; Liao, Shili; Long, Jiangping; Ma, Zhibang; Wang, Lisheng

    2016-11-01

    Duanqiao hydrothermal field is located between the Indomed and Gallieni fracture zones at the central volcano, at 50°28'E in the ultraslow-spreading Southwest Indian Ridge (SWIR). Twenty-eight subsamples from a relict chimney and massive sulfides were dated using the 230Th/238U method. Four main episodes of hydrothermal activity were determined according to the restricted results: 68.9-84.3, 43.9-48.4, 25.3-34.8, and 0.7-17.3 kyrs. Hydrothermal activity of Duanqiao probably started about 84.3 (±0.5) kyrs ago and ceased about 0.737 (±0.023) kyrs ago. The periodic character of hydrothermal activity may be related to the heat source provided by the interaction of local magmatism and tectonism. The estimated mean growth rate of the sulfide chimney is Dragon Flag field is much more recent than that of Duanqiao or Mt. Jourdanne fields. The massive sulfides are younger than the sulfides from other hydrothermal fields such as Rainbow, Sonne and Ashadze-2. The preliminarily estimated reserves of sulfide ores of Duanqiao are approximately 0.5-2.9 million tons.

  5. Observation of new microsecond isomers among fission products of 345 MeV/nucleon 238U

    CERN Document Server

    Kameda, D; Ohnishi, T; Kusaka, K; Yoshida, A; Yoshida, K; Ohtake, M; Fukuda, N; Takeda, H; Tanaka, K; Inabe, N; Yanagisawa, Y; Gono, Y; Watanabe, H; Otsu, H; Baba, H; Ichihara, T; Yamaguchi, Y; Takechi, M; Nishimura, S; Ueno, H; Yoshimi, A; Sakurai, H; Motobayashi, T; Nakao, T; Mizoi, Y; Matsushita, M; Ieki, K; Kobayashi, N; Tanaka, K; Kawada, Y; Tanaka, N; Deguchi, S; Satou, Y; Kondo, Y; Nakamura, T; Yoshinaga, K; Ishii, C; Yoshii, H; Miyashita, Y; Uematsu, N; Shiraki, Y; Sumikama, T; Chiba, J; Ideguchi, E; Saito, A; Yamaguchi, T; Hachiuma, I; Suzuki, T; Moriguchi, T; Ozawa, A; Ohtsubo, T; Famiano, M A; Geissel, H; Nettleton, A S; Tarasov, O B; Bazin, D; Sherrill, B M; Manikonda, S L; Nolen, J A

    2012-01-01

    A search for isomeric gamma-decays among fission fragments from 345 MeV/nucleon 238U has been performed at the RIKEN Nishina Center RI Beam Factory. Fission fragments were selected and identified using the superconducting in-flight separator BigRIPS and were implanted in an aluminum stopper. Delayed gamma-rays were detected using three clover-type high-purity germanium detectors located at the focal plane within a time window of 20 microseconds following the implantation. We identified a total of 54 microsecond isomers with half-lives of ~0.1 - 10 microseconds, including discovery of 18 new isomers in very neutron-rich nuclei: 59Tim, 90Asm, 92Sem, 93Sem, 94Brm, 95Brm, 96Brm, 97Rbm, 108Nbm, 109Mom, 117Rum, 119Rum, 120Rhm, 122Rhm, 121Pdm, 124Pdm, 124Agm and 126Agm, and obtained a wealth of spectroscopic information such as half-lives, gamma-ray energies, gamma-ray relative intensities and gamma-gamma coincidences over a wide range of neutron-rich exotic nuclei. Proposed level schemes are presented for 59Tim, 82...

  6. Angular distribution of fragments from neutron-induced fission of {sup 238}U in the intermediate energy region

    Energy Technology Data Exchange (ETDEWEB)

    Carlsson, Magnus

    2004-06-01

    Areas ranging from nuclear structure models to accelerator-driven systems benefit from improved neutron-induced fission data in the intermediate energy region. In this Master's degree thesis, the fragment angular distribution from fission of {sup 238}U, induced by 21-MeV neutrons, has been analysed from an experiment performed with the Medley/DIFFICILE setup at the The Svedberg Laboratory in Uppsala. The data have been corrected for low energy neutrons in the beam. The results agree with other experiments, as well as with model calculations. The data should be a starting point for further analysis with a goal to deduce the fission cross-section of {sup 238}U.

  7. Time-dependent Hartree-Fock calculations for multinucleon transfer and quasifission processes in $^{64}$Ni+$^{238}$U reaction

    CERN Document Server

    Sekizawa, Kazuyuki

    2016-01-01

    Background: Multinucleon transfer (MNT) and quasifission (QF) processes are dominant processes in low-energy collisions of two heavy nuclei. They are expected to be useful to produce neutron-rich unstable nuclei. Nuclear dynamics leading to these processes depends sensitively on nuclear properties such as deformation and shell structure. Purpose: We elucidate reaction mechanisms of MNT and QF processes involving heavy deformed nuclei, making detailed comparisons between microscopic TDHF calculations and measurements for $^{64}$Ni+$^{238}$U reaction. Methods: Three-dimensional Skyrme-TDHF calculations are performed. Particle-number projection method is used to evaluate MNT cross sections from the TDHF wave function after collision. Results: Fragment masses, total kinetic energy (TKE), scattering angle, contact time, and MNT cross sections are investigated for $^{64}$Ni+$^{238}$U reaction. They show reasonable agreements with measurements. At small impact parameters, collision dynamics depends sensitively on th...

  8. Estimation of uncertainties in resonance parameters of {sup 56}Fe, {sup 239}Pu, {sup 240}Pu and {sup 238}U

    Energy Technology Data Exchange (ETDEWEB)

    Nakagawa, Tsuneo; Shibata, Keiichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-05-01

    Uncertainties have been estimated for the resonance parameters of {sup 56}Fe, {sup 239}Pu, {sup 240}Pu and {sup 238}U contained in JENDL-3.2. Errors of the parameters were determined from the measurements which the evaluation was based on. The estimated errors have been compiled in the MF32 of the ENDF format. The numerical results are given in tables. (author)

  9. Fission Fragment Angular Distribution measurements of 235U and 238U at CERN n_TOF facility

    Directory of Open Access Journals (Sweden)

    Leal-Cidoncha E.

    2016-01-01

    In order to measure the FFAD of neutron-induced reactions, a fission detection setup based on parallel-plate avalanche counters (PPACs has been developed and successfully used at the CERN-n_TOF facility. In this work, we present the preliminary results on the analysis of new 235U(n,f and 238U(n,f data in the extended energy range up to 200 MeV compared to the existing experimental data.

  10. Solubility of {sup 238}U radionuclide from various types of soil in synthetic gastrointestinal fluids using “US in vitro” digestion method

    Energy Technology Data Exchange (ETDEWEB)

    Rashid, Nur Shahidah Abdul; Sarmani, Sukiman; Majid, Amran Ab.; Mohamed, Faizal; Siong, Khoo Kok, E-mail: khoo@ukm.edu.my [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia (UKM), 43600 Bangi, Selangor (Malaysia)

    2015-04-29

    238U radionuclide is a naturally occuring radioactive material that can be found in soil. In this study, the solubility of 238U radionuclide obtained from various types of soil in synthetic gastrointestinal fluids was analysed by “US P in vitro” digestion method. The synthetic gastrointestinal fluids were added to the samples with well-ordered, mixed throughly and incubated according to the human physiology digestive system. The concentration of 238U radionuclide in the solutions extracted from the soil was measured using Induced Coupling Plasma Mass Spectrometer (ICP-MS). The concentration of 238U radionuclide from the soil samples in synthetic gastrointestinal fluids showed different values due to different homogenity of soil types and chemical reaction of 238U radionuclide. In general, the solubility of 238U radionuclide in gastric fluid was higher (0.050 – 0.209 ppm) than gastrointestinal fluids (0.024 – 0.050 ppm). It could be concluded that the US P in vitro digestion method is practicle for estimating the solubility of 238U radionuclide from soil materials and could be useful for monitoring and risk assessment purposes applying to environmental, health and contaminated soil samples.

  11. Investigation of fission properties and evaporation residue measurement in the reactions using 238U target nucleus

    Directory of Open Access Journals (Sweden)

    Saro S.

    2011-10-01

    Full Text Available Fragment mass distributions for fission after full momentum transfer were measured in the reactions of 30Si,34,36 S,31P,40Ar + 238U at bombarding energies around the Coulomb barrier. Mass distributions change significantly as a function of incident beam energy. The asymmetric fission probability increases at sub-barrier energy. The phenomenon is interpreted as an enhanced quasifission probability owing to orientation effects on fusion and/or quasifission. The evaporation residue (ER cross sections were measured in the reactions of 30Si + 238U and 34S + 238U to obtain information on fusion. In the latter reaction, significant suppression of fusion was implied. This suggests that fission events different from compound nucleus are included in the masssymmetric fragments. The results are supported by a model calculation based on a dynamical calculation using Langevin equation, in which the mass distribution for fusion-fission and quasifission fragments are separately determined.

  12. Radioactivity of Natural Nuclides (40K, 238U, 232Th, 226Ra in Coals from Eastern Yunnan, China

    Directory of Open Access Journals (Sweden)

    Xin Wang

    2015-09-01

    Full Text Available The naturally occurring primordial radionuclides in coals might exhibit high radioactivity, and can be exported to the surrounding environment during coal combustion. In this study, nine coal samples were collected from eastern Yunnan coal deposits, China, aiming at characterizing the overall radioactivity of some typical nuclides (i.e., 40K, 238U, 232Th, 226Ra and assessing their ecological impact. The mean activity concentrations of 238U, 232Th, 40K and 226Ra are 63.86 (17.70–92.30 Bq· kg-1, 23.76 (11.10–37.10 Bq· kg-1, 96.84 (30.60–229.30 Bq· kg-1 and 28.09 Bq·kg-1 (3.10–61.80 Bq·kg-1, respectively. Both 238U and 232Th have high correlations with ash yield of coals, suggesting their inorganic origins. The overall environmental effect of natural radionuclides in studied coals is considered to be negligible, as assessed by related indexes (i.e., radium equivalent activity, air-adsorbed dose rate, annual effective dose, and external hazard index. However, the absorbed dose rates values are higher than the average value of global primordial radiation and the Chinese natural gamma radiation dose rate.

  13. Investigation of the 238U(d ,p ) surrogate reaction via the simultaneous measurement of γ -decay and fission probabilities

    Science.gov (United States)

    Ducasse, Q.; Jurado, B.; Aïche, M.; Marini, P.; Mathieu, L.; Görgen, A.; Guttormsen, M.; Larsen, A. C.; Tornyi, T.; Wilson, J. N.; Barreau, G.; Boutoux, G.; Czajkowski, S.; Giacoppo, F.; Gunsing, F.; Hagen, T. W.; Lebois, M.; Lei, J.; Méot, V.; Morillon, B.; Moro, A. M.; Renstrøm, T.; Roig, O.; Rose, S. J.; Sérot, O.; Siem, S.; Tsekhanovich, I.; Tveten, G. M.; Wiedeking, M.

    2016-08-01

    We investigated the 238U(d ,p ) reaction as a surrogate for the n +238U reaction. For this purpose we measured for the first time the γ -decay and fission probabilities of *239U simultaneously and compared them to the corresponding neutron-induced data. We present the details of the procedure to infer the decay probabilities, as well as a thorough uncertainty analysis, including parameter correlations. Calculations based on the continuum-discretized coupled-channels method and the distorted-wave Born approximation (DWBA) were used to correct our data from detected protons originating from elastic and inelastic deuteron breakup. In the region where fission and γ emission compete, the corrected fission probability is in agreement with neutron-induced data, whereas the γ -decay probability is much higher than the neutron-induced data. We have performed calculations of the decay probabilities with the statistical model and of the average angular momentum populated in the 238U(d ,p ) reaction with the DWBA to interpret these results.

  14. Uranium-series constraints on radionuclide transport and groundwater flow at the Nopal I uranium deposit, Sierra Pena Blanca, Mexico.

    Science.gov (United States)

    Goldstein, Steven J; Abdel-Fattah, Amr I; Murrell, Michael T; Dobson, Patrick F; Norman, Deborah E; Amato, Ronald S; Nunn, Andrew J

    2010-03-01

    Uranium-series data for groundwater samples from the Nopal I uranium ore deposit were obtained to place constraints on radionuclide transport and hydrologic processes for a nuclear waste repository located in fractured, unsaturated volcanic tuff. Decreasing uranium concentrations for wells drilled in 2003 are consistent with a simple physical mixing model that indicates that groundwater velocities are low ( approximately 10 m/y). Uranium isotopic constraints, well productivities, and radon systematics also suggest limited groundwater mixing and slow flow in the saturated zone. Uranium isotopic systematics for seepage water collected in the mine adit show a spatial dependence which is consistent with longer water-rock interaction times and higher uranium dissolution inputs at the front adit where the deposit is located. Uranium-series disequilibria measurements for mostly unsaturated zone samples indicate that (230)Th/(238)U activity ratios range from 0.005 to 0.48 and (226)Ra/(238)U activity ratios range from 0.006 to 113. (239)Pu/(238)U mass ratios for the saturated zone are 1000 times lower than the U mobility. Saturated zone mobility decreases in the order (238)U approximately (226)Ra > (230)Th approximately (239)Pu. Radium and thorium appear to have higher mobility in the unsaturated zone based on U-series data from fractures and seepage water near the deposit.

  15. Uranium-series constraints on radionuclide transport and groundwater flow at the Nopal I uranium deposit, Sierra Pena Blanca, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Goldstein, S.J.; Abdel-Fattah, A.I.; Murrell, M.T.; Dobson, P.F.; Norman, D.E.; Amato, R.S.; Nunn, A. J.

    2009-10-01

    Uranium-series data for groundwater samples from the Nopal I uranium ore deposit were obtained to place constraints on radionuclide transport and hydrologic processes for a nuclear waste repository located in fractured, unsaturated volcanic tuff. Decreasing uranium concentrations for wells drilled in 2003 are consistent with a simple physical mixing model that indicates that groundwater velocities are low ({approx}10 m/y). Uranium isotopic constraints, well productivities, and radon systematics also suggest limited groundwater mixing and slow flow in the saturated zone. Uranium isotopic systematics for seepage water collected in the mine adit show a spatial dependence which is consistent with longer water-rock interaction times and higher uranium dissolution inputs at the front adit where the deposit is located. Uranium-series disequilibria measurements for mostly unsaturated zone samples indicate that {sup 230}Th/{sup 238}U activity ratios range from 0.005-0.48 and {sup 226}Ra/{sup 238}U activity ratios range from 0.006-113. {sup 239}Pu/{sup 238}U mass ratios for the saturated zone are <2 x 10{sup -14}, and Pu mobility in the saturated zone is >1000 times lower than the U mobility. Saturated zone mobility decreases in the order {sup 238}U{approx}{sup 226}Ra > {sup 230}Th{approx}{sup 239}Pu. Radium and thorium appear to have higher mobility in the unsaturated zone based on U-series data from fractures and seepage water near the deposit.

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

    Energy Technology Data Exchange (ETDEWEB)

    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 ({sup 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 {sup 238}U can be found, and {sup 238}U behavior in the environment and in the human body.

  17. Tracing of natural radionuclides mobility in deep sedimentary environment using radioactive ({sup 234}U/{sup 238}U) disequilibria: application to the Mesozoic formations of the Eastern part of the Paris Basin; Tracage de la mobilite des radionucleides naturels en milieu sedimentaire profond a l'aide des desequilibres radioactifs ({sup 234}U/{sup 238}U): application aux formations mesozoiques de l'est du Bassin de Paris

    Energy Technology Data Exchange (ETDEWEB)

    Deschamps, P

    2003-11-01

    This thesis forms part of the geological investigations undertaken by the French agency for nuclear waste management, ANDRA, around the Meuse/Haute-Marne Underground Research Laboratory (URL) located in the Eastern part of the Paris Basin in order to evaluate the feasibility of high-level radioactive waste repository in deep argilite formations. The aim of the study is to examine the radionuclide migration in the deep Callovo-Oxfordian target argilite layer and its surrounding low- permeability Bathonian and Oxfordian limestone formations in order to assess the long term confining capacities of the sedimentary series. This study is based on measurement of radioactive disequilibria within U-series by Multiple- Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICP-MS). The high precision and accuracy achieved allowed to demonstrate the {sup 234}U/{sup 238}U radioactive equilibrium in the Callovo-Oxfordian argilites. This result shows the uranium immobility in the target formation and provides a strong evidence for the current chemical stability and closure of the system for uranium and most probably for the other actinides. This is a fundamental result with respect to the problematic of disposal of high level radioactive waste in deep geological formation since it provides a in situ indication of the confining capacities of the clayey target formation in the current settings. Conversely, ({sup 234}U/{sup 238}U) disequilibria are systematically observed within zones, located in the surrounding carbonate formations, that are characterized by pressure dissolution structures (stylolites or dissolution seams). These disequilibria provide evidence for a discrete uranium relocation during the last two million years in the vicinity of stylolitic structures. This is a surprising result since it is generally supposed that these deep, low permeability, compact formations behave as closed system at the time scale of the U-series. (author)

  18. Measurement of 238U muonic x-rays with a germanium detector setup

    Energy Technology Data Exchange (ETDEWEB)

    Esch, Ernst I [Los Alamos National Laboratory; Jason, Andrew [Los Alamos National Laboratory; Miyadera, Haruo [Los Alamos National Laboratory; Hoteling, Nathan J [Los Alamos National Laboratory; Heffner, Robert H [Los Alamos National Laboratory; Adelmann, Andreas [PAUL SCHERRER INSTITUT; Stocki, Trevor [HEALTH CANADA; Mitchell, Lee [NAVAL RESEARCH LAB

    2009-01-01

    In the field of nuclear non-proliferation muon interactions with materials are of great interest. This paper describes an experiment conducted at the Paul Scherrer Institut (PSI) in Switzerland where a muon beam is stopped in a uranium target. The muons produce characteristic muonic x-rays. Muons will penetrate shielding easily and the produced characteristic x-rays can be used for positive isotope identification. Furthermore, the x-rays for uranium isotopes lie in the energy range of 6-7 MeV, which allows them to have an almost optimal mean free path in heavy shielding such as lead or steel. A measurement was conducted at PSI to prove the feasibility of detecting muonic x-rays from a large sample of depleted uranium (several kilograms) with a germanium detector. In this paper, the experimental setup and analysis of the measurement itself is presented.

  19. Iowa Bedrock Geology

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — The bedrock geologic map portrays the current interpretation of the distribution of various bedrock stratigraphic units present at the bedrock surface. The bedrock...

  20. The study of equivalent dose of uranium in long bean (V. U. Sesquipedalis) and the effect on human

    Energy Technology Data Exchange (ETDEWEB)

    Rashid, Nur Shahidah Abdul; Yoshandi, Tengku Mohammad; Majid, Sukiman Sarmania Amran Ab.; Mohamed, Faizal; Siong, Khoo Kok, E-mail: khoo@ukm.edu.my [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia (UKM), 43600 Bangi, Selangor (Malaysia)

    2016-01-22

    In the case of accidental release of Uranium-238 ({sup 238}U) radionuclides in a nuclear facility or in the environment, internal contamination by either acute or chronic exposure has the potential to induce both radiological and chemical toxic effects. A study was conducted to estimate the {sup 238}U radionuclide concentration in the long beans using Induced Coupled Mass Plasma-Spectrometry (ICP-MS). {sup 238}U radionuclide is a naturally occurring radioactive material that can be found in soil and can be transferred to the long bean (Vigna unguiculata subsp. Sesquapedalis) directly or indirectly via water or air. Kidney and liver are the major sites of deposition of {sup 238}U radionuclide. The obtained dose exposed in the liver and kidney is used to assess the safety level for public intake of {sup 238}U radionuclide from the consumption of long beans. The concentration of {sup 238}U radionuclide measured in long bean samples was 0.0226 ± 0.0009 mg/kg. Total activity of {sup 238}U radionuclide was 0.0044 ± 0.0002 Bq/day with the daily intake of 0.3545 ± 0.0143 µg/day and the annual committed effective dose due to ingestion of {sup 238}U radionuclide in long beans was 0.2230 ± 0.0087 µSv/year. The committed equivalent dose of {sup 238}U radionuclide from the assessment in the liver and kidney are 0.4198 ± 0.0165 nSv and 10.9335 ± 0.4288 nSv. The risk of cancer of {sup 238}U radionuclide was determined to be (86.0466 ± 3.3748) × 10-9. Thus, the results concluded that {sup 238}U radionuclide in local long beans was in the permitted level and safe to consume without posing any significant radiological threat to population.

  1. The study of equivalent dose of uranium in long bean (V. U. Sesquipedalis) and the effect on human

    Science.gov (United States)

    Rashid, Nur Shahidah Abdul; Yoshandi, Tengku Mohammad; Majid, Sukiman Sarmania Amran Ab.; Mohamed, Faizal; Siong, Khoo Kok

    2016-01-01

    In the case of accidental release of Uranium-238 (238U) radionuclides in a nuclear facility or in the environment, internal contamination by either acute or chronic exposure has the potential to induce both radiological and chemical toxic effects. A study was conducted to estimate the 238U radionuclide concentration in the long beans using Induced Coupled Mass Plasma-Spectrometry (ICP-MS). 238U radionuclide is a naturally occurring radioactive material that can be found in soil and can be transferred to the long bean (Vigna unguiculata subsp. Sesquapedalis) directly or indirectly via water or air. Kidney and liver are the major sites of deposition of 238U radionuclide. The obtained dose exposed in the liver and kidney is used to assess the safety level for public intake of 238U radionuclide from the consumption of long beans. The concentration of 238U radionuclide measured in long bean samples was 0.0226 ± 0.0009 mg/kg. Total activity of 238U radionuclide was 0.0044 ± 0.0002 Bq/day with the daily intake of 0.3545 ± 0.0143 µg/day and the annual committed effective dose due to ingestion of 238U radionuclide in long beans was 0.2230 ± 0.0087 µSv/year. The committed equivalent dose of 238U radionuclide from the assessment in the liver and kidney are 0.4198 ± 0.0165 nSv and 10.9335 ± 0.4288 nSv. The risk of cancer of 238U radionuclide was determined to be (86.0466 ± 3.3748) × 10-9. Thus, the results concluded that 238U radionuclide in local long beans was in the permitted level and safe to consume without posing any significant radiological threat to population.

  2. 238U-230Th dating of chevkinite in high-silica rhyolites from La Primavera and Yellowstone calderas

    Science.gov (United States)

    Vazquez, Jorge A.; Velasco, Noel O.; Schmitt, Axel K.; Bleick, Heather A.; Stelten, Mark E.

    2014-01-01

    Application of 238U-230Th disequilibrium dating of accessory minerals with contrasting stabilities and compositions can provide a unique perspective on magmatic evolution by placing the thermochemical evolution of magma within the framework of absolute time. Chevkinite, a Th-rich accessory mineral that occurs in peralkaline and metaluminous rhyolites, may be particularly useful as a chronometer of crystallization and differentiation because its composition may reflect the chemical changes of its host melt. Ion microprobe 128U-230Th dating of single chevkinite microphenocrysts from pre- and post-caldera La Primavera, Mexico, rhyolites yields model crystallization ages that are within 10's of k.y. of their corresponding K-Ar ages of ca. 125 ka to 85 ka, while chevkinite microphenocrysts from a post-caldera Yellowstone, USA, rhyolite yield a range of ages from ca. 110 ka to 250 ka, which is indistinguishable from the age distribution of coexisting zircon. Internal chevkinite-zircon isochrons from La Primavera yield Pleistocene ages with ~5% precision due to the nearly two order difference in Th/U between both minerals. Coupling chevkinite 238U-230Th ages and compositional analyses reveals a secular trend of Th/U and rare earth elements recorded in Yellowstone rhyolite, likely reflecting progressive compositional evolution of host magma. The relatively short timescale between chevkinite-zircon crystallization and eruption suggests that crystal-poor rhyolites at La Primavera were erupted shortly after differentiation and/or reheating. These results indicate that 238U-230Th dating of chevkinite via ion microprobe analysis may be used to date crystallization and chemical evolution of silicic magmas.

  3. Gamma Emission Spectra from Neutron Resonances in 234,236,238U Measured Using the Dance Detector at Lansce

    Science.gov (United States)

    Ullmann, J. L.; Bredeweg, T. A.; Couture, A. J.; Haight, R. C.; Jandel, M.; Kawano, T.; Keksis, A. L.; O'Donnell, J. M.; Rundberg, R. S.; Vieira, D. J.; Wouters, J. M.; Wilhelmy, J. B.; Wu, C. Y.; Becker, J. A.; Chyzh, A.; Baramsai, B.; Mitchell, G. E.; Krticka, M.

    2013-03-01

    An accurate knowledge of the radiative strength function and level density is needed to calculate of neutron-capture cross sections. An additional constraint on these quantities is provided by measurements of γ-ray emission spectra following capture. We present γ-emission spectra from several neutron resonances in 234,236,238U, measured using the DANCE detector at LANSCE. The measurements are compared to preliminary calculations of the cascade. It is observed that the generalized Lorentzian form of the E1 strength function cannot reproduce the shape of the emission spectra, but a better description is made by adding low-lying M1 Lorentzian strength.

  4. Multi-modal calculations of prompt fission neutrons from 238U(n, f) at low induced energy

    Institute of Scientific and Technical Information of China (English)

    ZHENG Na; ZHONG Chun-Lai; FAN Tie-Shuan

    2011-01-01

    Properties of prompt fission neutrons from 238U(n,f) are calculated for incident neutron energies below 6 MeV using the multi-modal model,including the prompt fission neutron spectrum,the average prompt fission neutron multiplicity,and the prompt fission neutron multiplicity as a function of the fission fragment mass v(A) (usually named “sawtooth” data) The three most dominant fission modes are taken into account.The model parameters are determined on the basis of experimental fission fragment data.The predicted results are in good agreement with the experimental data.

  5. Extensive radioactive characterization of a phosphogypsum stack in SW Spain: {sup 226}Ra, {sup 238}U, {sup 210}Po concentrations and {sup 222}Rn exhalation rate

    Energy Technology Data Exchange (ETDEWEB)

    Abril, Jose-Maria, E-mail: jmabril@us.es [Dpto. Fisica Aplicada I, Universidad de Sevilla, EUITA, Ctra Utrera Km 1, 41013 Seville (Spain); Garcia-Tenorio, Rafael, E-mail: gtenorio@us.es [Dpto. Fisica Aplicada II, Universidad de Sevilla, ETSA, Avda. Reina Mercedes s/n, 41012 Seville (Spain); Manjon, Guillermo, E-mail: manjon@us.es [Dpto. Fisica Aplicada II, Universidad de Sevilla, ETSA, Avda. Reina Mercedes s/n, 41012 Seville (Spain)

    2009-05-30

    Phosphogypsum (PG) is a by-product of the phosphate fertilizer industries that contains relatively high concentrations of uranium series radionuclides. The US-EPA regulates the agriculture use of PG, attending to its {sup 226}Ra content and to the {sup 222}Rn exhalation rate from inactive stacks. Measurements of {sup 222}Rn exhalation rates in PG stacks typically show a large and still poorly understood spatial and temporal variability, and the published data are scarce. This work studies an inactive PG stack in SW Spain of about 0.5 km{sup 2} from where PG can be extracted for agriculture uses, and an agriculture soil 75 km apart, being representative of the farms to be amended with PG. Activity concentrations of {sup 226}Ra, {sup 238}U and {sup 210}Po have been measured in 30 PG samples (0-90 cm horizon) allowing for the construction of maps with spatial distributions in the PG stack and for the characterization of the associated PG inputs to agriculture soils. Averaged {sup 226}Ra concentrations for the stack were 730 {+-} 60 Bq kg{sup -1} (d.w.), over the US-EPA limit of 370 Bq kg{sup -1}. {sup 222}Rn exhalation rate has been measured by the charcoal canister method in 49 sampling points with 3 canisters per sampling point. Values in PG stack were under the US-EPA limit of 2600 Bq m{sup -2} h{sup -1}, but they were one order of magnitude higher than those found in the agriculture soil. Variability in radon emissions has been studied at different spatial scales. Radon exhalation rates were correlated with {sup 226}Ra concentrations and daily potential evapotranspiration (ETo). They increased with ETo in agriculture soils, but showed an opposite behaviour in the PG stack.

  6. Extensive radioactive characterization of a phosphogypsum stack in SW Spain: 226Ra, 238U, 210Po concentrations and 222Rn exhalation rate.

    Science.gov (United States)

    Abril, José-María; García-Tenorio, Rafael; Manjón, Guillermo

    2009-05-30

    Phosphogypsum (PG) is a by-product of the phosphate fertilizer industries that contains relatively high concentrations of uranium series radionuclides. The US-EPA regulates the agriculture use of PG, attending to its (226)Ra content and to the (222)Rn exhalation rate from inactive stacks. Measurements of (222)Rn exhalation rates in PG stacks typically show a large and still poorly understood spatial and temporal variability, and the published data are scarce. This work studies an inactive PG stack in SW Spain of about 0.5 km(2) from where PG can be extracted for agriculture uses, and an agriculture soil 75 km apart, being representative of the farms to be amended with PG. Activity concentrations of (226)Ra, (238)U and (210)Po have been measured in 30 PG samples (0-90 cm horizon) allowing for the construction of maps with spatial distributions in the PG stack and for the characterization of the associated PG inputs to agriculture soils. Averaged (226)Ra concentrations for the stack were 730+/-60 Bq kg(-1) (d.w.), over the US-EPA limit of 370 Bq kg(-1). (222)Rn exhalation rate has been measured by the charcoal canister method in 49 sampling points with 3 canisters per sampling point. Values in PG stack were under the US-EPA limit of 2600 Bq m(-2)h(-1), but they were one order of magnitude higher than those found in the agriculture soil. Variability in radon emissions has been studied at different spatial scales. Radon exhalation rates were correlated with (226)Ra concentrations and daily potential evapotranspiration (ETo). They increased with ETo in agriculture soils, but showed an opposite behaviour in the PG stack.

  7. Primordial radioactivity ((238)U, (232)Th and (40)K) measurements for soils of Ludhiana district of Punjab, India.

    Science.gov (United States)

    Badhan, K; Mehra, R

    2012-11-01

    The aim of the present work was to study the activity concentration and absorbed gamma dose rates due to primordial radionuclides ((238)U, (232)Th and (40)K) for the soil of different villages of Ludhiana district of Punjab, India using a high-purity germanium detector based on high resolution gamma-ray spectrometry. The average activity concentrations of (238)U, (232)Th and (40)K in the soil samples have been found to be 28.58, 50.95 and 569.59 Bq kg(-1), respectively, which gives the total gamma dose rate contribution of 68.50 nGy h(-1). To evaluate the radiological hazard of the natural radioactivity, the radium equivalent activity, the external hazard index, the absorbed dose rate and the effective dose rate have been calculated. The calculated radium equivalent activity values are on the lower side of the recommended safe limit value of 370 Bq kg(-1) by Organization of Economic and Control Department. The calculated value of external health hazard index is lower than unity.

  8. Photofission product yields of {sup 238}U and {sup 239}Pu with 22-MeV bremsstrahlung

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Xianfei; Yang, Haori, E-mail: haori.yang@oregonstate.edu

    2016-06-11

    In homeland security and nuclear safeguards applications, non-destructive techniques to identify and quantify special nuclear materials are in great demand. Although nuclear materials naturally emit characteristic radiation (e.g. neutrons, γ-rays), their intensity and energy are normally low. Furthermore, such radiation could be intentionally shielded with ease or buried in high-level background. Active interrogation techniques based on photofission have been identified as effective assay approaches to address this issue. In designing such assay systems, nuclear data, like photofission product yields, plays a crucial role. Although fission yields for neutron-induced reactions have been well studied and readily available in various nuclear databases, data on photofission product yields is rather scarce. This poses a great challenge to the application of photofission techniques. In this work, short-lived high-energy delayed γ-rays from photofission of {sup 238}U were measured in between linac pulses. In addition, a list-mode system was developed to measure relatively long-lived delayed γ-rays from photofission of {sup 238}U and {sup 239}Pu after the irradiation. Time and energy information of each γ-ray event were simultaneously recorded by this system. Cumulative photofission product yields were then determined using the measured delayed γ-ray spectra.

  9. Determination of specific concentrations of {sup 40}K, {sup 238}U and {sup 232}Th in mineral fertilizer samples

    Energy Technology Data Exchange (ETDEWEB)

    Garcez, Ricardo W.D.; Lopes, Jose M.; Silva, Ademir X., E-mail: r.w.o.g@fisica.if.uff.br, E-mail: ademir@nuclear.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear; Domingues, Alessandro M.; Lima, Marco F. [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil)

    2015-07-01

    The use of fertilizer is an established practice worldwide to promote agricultural productivity increased without increasing the planted area, resulting in native forests protection and increase of the food availability. Some kinds of fertilizer have in their chemical composition some radionuclides due the origin of its feedstock, such as {sup 238}U, the {sup 232}Th, and their descendants, beyond {sup 40}K. Knowledge of the radioactivity levels in the environment is great importance to know the gamma radiation dose that the human being is exposed. For identification and quantitation of radionuclides, it was used gamma spectrometry where HPGe detector was used to obtain the spectra, and LabSOCS software for calculating the detection efficiency for each energy. The values of {sup 232}Th specific concentrations ranged from 4.1 to 368.1 Bq.Kg{sup -1}, the values of {sup 238}U specific concentrations ranged from 16.0 to 647.7 Bq.Kg{sup -1} and {sup 40}K specific concentrations ranged from 19.1 to 12713 Bq.Kg{sup -1}. Concentrations of values are consistent with those found in literature. (author)

  10. Spectral interference corrections for the measurement of (238)U in materials rich in thorium by a high resolution gamma-ray spectrometry.

    Science.gov (United States)

    Yücel, H; Solmaz, A N; Köse, E; Bor, D

    2009-11-01

    In this study, the spectral interferences are investigated for the analytical peaks at 63.3 keV of (234)Th and 1001.0 keV of (234m)Pa, which are often used in the measurement of (238)U activity by the gamma-ray spectrometry. The correction methods are suggested to estimate the net peak areas of the gamma-rays overlapping the analytical peaks, due to the contribution of (232)Th that may not be negligible in materials rich in natural thorium. The activity results for the certified reference materials (CRMs) containing U and Th were measured with a well type Ge detector. The self-absorption and true coincidence-summing (TCS) effects were also taken into account in the measurements. It is found that ignoring the contributions of the interference gamma-rays of (232)Th and (235)U to the mixed peak at 63.3 keV of (234)Th ((238)U) leads to the remarkably large systematic influence of 0.8-122% in the measured (238)U activity, but in case of ignoring the contribution of (232)Th via the interference gamma-ray at 1000.7 keV of (228)Ac to the mixed peak at 1001 keV of (234m)Pa ((238)U) results in relatively smaller systematic influence of 0.05-3%, depending on thorium contents in the samples. The present results showed that the necessary correction for the spectral interferences besides self-absorption and TCS effects is also very important to obtain more accurate (238)U activity results. Additionally, if one ignores the contribution of (232)Th to both (238)U and (40)K activities in materials, the maximum systematic influence on the effective radiation dose is estimated to be ~6% and ~1% via the analytical peaks at 63.3 and 1001 keV for measurement of the (238)U activity, respectively.

  11. Trace metal cycling and 238U/235U in New Zealand's fjords: Implications for reconstructing global paleoredox conditions in organic-rich sediments

    Science.gov (United States)

    Hinojosa, Jessica L.; Stirling, Claudine H.; Reid, Malcolm R.; Moy, Christopher M.; Wilson, Gary S.

    2016-04-01

    Reconstructing the history of ocean oxygenation provides insight into links between ocean anoxia, biogeochemical cycles, and climate. Certain redox-sensitive elements respond to changes in marine oxygen content through phase shifts and concomitant isotopic fractionation, providing new diagnostic proxies of past ocean hypoxia. Here we explore the behavior and inter-dependence of a suite of commonly utilized redox-sensitive trace metals (U, Mo, Fe, and Mn) and the emerging "stable" isotope system of U (238U/235U, or δ238U) in New Zealand fjords. These semi-restricted basins have chemical conditions spanning the complete redox spectrum from fully oxygenated to suboxic to intermittently anoxic/euxinic. In the anoxic water column, U and Mo concentrations decrease, while Fe and Mn concentrations increase. Similarly, signals of past euxinic conditions can be found by U, Mo, Fe, and Mn enrichment in the underlying sediments. The expected U isotopic shift toward a lower δ238U in the anoxic water column due to U(VI)-U(IV) reduction is not observed; instead, water column δ238U profiles are consistent in fjords of all oxygen content, falling within previously reported ranges for open ocean seawater (δ238U = -0.42 ± 0.07‰). Additionally, surface sediment δ238U results show evidence for competing U isotope fractionation processes. One site indicates increased export of 238U from seawater to the underlying sediments (fractionation between aqueous seawater U and particulate sediment U, or ΔU(aq)-U(solid) = -0.25‰), consistent with redox-driven fractionation. Another site suggests potential U(VI) adsorption-driven fractionation, reflecting increased export of 235U from seawater to sediments (ΔU(aq)-U(solid) = 0.25‰). We discuss several potential factors that could alter δ238U in waters and sediments beyond redox-driven shifts, including adsorption to organic matter in waters of high primary productivity, reaction rates for competing processes of U adsorption and

  12. Variation of uranium isotopic composition in soil within the JCO grounds from the 30 September 1999 criticality accident at JCO, Tokai-mura, Japan.

    Science.gov (United States)

    Yamamoto, Masayoshi; Kawabata, Yoshiko; Murata, Yoshimasa; Komura, Kazuhisa

    2002-08-01

    Following the 30 September 1999 criticality accident at JCO, 29 surface and 3 core soil samples were collected inside and outside the JCO grounds to evaluate possible contamination by 235U-enriched uranium (18.8%) being handled at the time of the accident. Uranium (234U, 235U, and 238U) and thorium (228Th, 230Th, and 232Th) isotopes were determined by alpha-spectrometry and ICP-MS after radiochemical separation. Concentrations of 238U and 234U ranged from 11.3 to 63.5 and 11.6 to 360 mBq g(-1), respectively. Higher amounts of 238U and/or 234U were found in the vicinity of the uranium conversion building. The calculated 234U/235U activity ratios ranged from a 1.0 radioactive equilibrium value to an unusually high 5.7 value. Several of the soil samples showed considerably higher 235U/238U atomic ratios (1.06-4.37%) than 0.725% for natural uranium. Based on the assumption that measured U-series nuclides in soil samples taken from the JCO grounds were almost at radioactive equilibrium up to 230Th, excess uranium could be calculated for each sample. The results suggest that the excess uranium in the soils have lower 235U/238U atomic ratios (a few %) than the 18.8% enrichment of the precipitation tank uranium.

  13. Determination of uranium concentration in ground water samples of Northern Greece

    Directory of Open Access Journals (Sweden)

    Pashalidis I.

    2012-04-01

    Full Text Available The activity concentration of 238U and 234U has been determined in groundwater samples of hot springs and deep wells from the region of Northern Greece. The analysis was performed by alpha spectroscopy after pre-concentration and separation of uranium by cation exchange (Chelex 100 resin and finally its electro-deposition on stainless steel discs. The uranium concentration in deep wells and springs varies strongly between 0.15 and 7.66 μg l−1. Generally the springs present higher uranium concentration than the deep wells, except of the Apol-lonia spring, which has shown the lowest value of 0.15 mg l−1. 238U and 234U activity concentration ranged between 1.8–95.3 mBq l−1 and 1.7–160.1 mBq l−1, respectively. The obtained isotopic ratio 234U/238U varies between 0.95 and 1.74 which means that the two isotopes are not in radioactive equilibrium. The highest 234U/238U activity ratio values correspond to the Langada springs, indicating most probably old-type waters. On the other hand, ground waters from wells with relatively low uranium activity concentration and low 234U/238U isotopic ratios, point to the presence of younger waters with a stronger contribution of a local recharge component to the groundwater.

  14. The terrestrial uranium isotope cycle.

    Science.gov (United States)

    Andersen, Morten B; Elliott, Tim; Freymuth, Heye; Sims, Kenneth W W; Niu, Yaoling; Kelley, Katherine A

    2015-01-15

    Changing conditions on the Earth's surface can have a remarkable influence on the composition of its overwhelmingly more massive interior. The global distribution of uranium is a notable example. In early Earth history, the continental crust was enriched in uranium. Yet after the initial rise in atmospheric oxygen, about 2.4 billion years ago, the aqueous mobility of oxidized uranium resulted in its significant transport to the oceans and, ultimately, by means of subduction, back to the mantle. Here we explore the isotopic characteristics of this global uranium cycle. We show that the subducted flux of uranium is isotopically distinct, with high (238)U/(235)U ratios, as a result of alteration processes at the bottom of an oxic ocean. We also find that mid-ocean-ridge basalts (MORBs) have (238)U/(235)U ratios higher than does the bulk Earth, confirming the widespread pollution of the upper mantle with this recycled uranium. Although many ocean island basalts (OIBs) are argued to contain a recycled component, their uranium isotopic compositions do not differ from those of the bulk Earth. Because subducted uranium was probably isotopically unfractionated before full oceanic oxidation, about 600 million years ago, this observation reflects the greater antiquity of OIB sources. Elemental and isotope systematics of uranium in OIBs are strikingly consistent with previous OIB lead model ages, indicating that these mantle reservoirs formed between 2.4 and 1.8 billion years ago. In contrast, the uranium isotopic composition of MORB requires the convective stirring of recycled uranium throughout the upper mantle within the past 600 million years.

  15. Extreme fractionation of 234U /238U and 230Th /234U in spring waters, sediments, and fossils at the Pomme de Terre Valley, southwestern Missouri

    Science.gov (United States)

    Szabo, Barney J.

    1982-09-01

    Isotopic fractionation as great as 1600% exists between 234U and 238U in spring waters, sediments, and fossils in the Pomme de Terre Valley, southwestern Missouri. The activity ratios of 234U /238U in five springs range from 7.2 to 16 in water which has been discharged for at least the past 30,000 years. The anomalies in 234U /238U ratio in deep water have potential usefulness in hydrologic investigations in southern Missouri. Clayey units overlying the spring bog sediments of Trolinger Spring are enriched in 230Th relative to their parent 234U by as much as 720%. The results indicate that both preferential displacement via alpha recoil ejection and the preferential emplacement via recoiling and physical entrapment are significant processes that are occurring in the geologic environment.

  16. Extreme fractionation of 234U 238U and 230Th 234U in spring waters, sediments, and fossils at the Pomme de Terre Valley, southwestern Missouri

    Science.gov (United States)

    Szabo, B. J.

    1982-01-01

    Isotopic fractionation as great as 1600% exists between 234U and 238U in spring waters, sediments, and fossils in the Pomme de Terre Valley, southwestern Missouri. The activity ratios of 234U 238U in five springs range from 7.2 to 16 in water which has been discharged for at least the past 30,000 years. The anomalies in 234U 238U ratio in deep water have potential usefulness in hydrologic investigations in southern Missouri. Clayey units overlying the spring bog sediments of Trolinger Spring are enriched in 230Th relative to their parent 234U by as much as 720%. The results indicate that both preferential displacement via alpha recoil ejection and the preferential emplacement via recoiling and physical entrapment are significant processes that are occurring in the geologic environment. ?? 1982.

  17. Study of 236U/238U ratio at CIRCE using a 16-strip silicon detector with a TOF system

    Directory of Open Access Journals (Sweden)

    De Cesare M.

    2015-01-01

    Full Text Available Accelerator Mass Spectrometry (AMS is presently the most sensitive technique for the measurement of long-lived actinides, e.g. 236U and xPu isotopes. A new actinide AMS system, based on a 3-MV pelletron tandem accelerator, is operated at the Center for Isotopic Research on Cultural and Environmental Heritage (CIRCE in Caserta, Italy. In this paper we report on the procedure adopted to increase the 236U abundance sensitivity as low as possible. The energy and position determinations of the 236U ions, using a 16-strip silicon detector have been obtained. A 236U/238U isotopic ratio background level of about 2.9×10−11 was obtained, summing over all the strips, using a Time of Flight-Energy (TOF-E system with a 16-strip silicon detector (4.9×10−12 just with one strip.

  18. Isotopic Yield Distributions of Transfer- and Fusion-Induced Fission from 238U+12C Reactions in Inverse Kinematics

    CERN Document Server

    Caamaño, M; Farget, F; Derkx, X; Schmidt, K -H; Audouin, L; Bacri, C -O; Barreau, G; Benlliure, J; Casarejos, E; Chbihi, A; Fernandez-Dominguez, B; Gaudefroy, L; Golabek, C; Jurado, B; Lemasson, A; Navin, A; Rejmund, M; Roger, T; Shrivastava, A; Schmitt, C

    2013-01-01

    A novel method to access the complete identification in atomic number Z and mass A of fragments produced in low-energy fission of actinides is presented. This method, based on the use of multi- nucleon transfer and fusion reactions in inverse kinematics, is applied in this work to reactions between a 238U beam and a 12C target to produce and induce fission of moderately excited actinides. The fission fragments are detected and fully identified with the VAMOS spectrometer of GANIL, allowing the measurement of fragment yields of several hundreds of isotopes in a range between A ~ 80 and ~ 160, and from Z ~ 30 to ~ 64. For the first time, complete isotopic yield distributions of fragments from well-defined fissioning systems are available. Together with the precise measurement of the fragment emission angles and velocities, this technique gives further insight into the nuclear-fission process.

  19. Symmetric splitting for the system /sup 32/S+/sup 238/U at energies near and below the barrier

    Energy Technology Data Exchange (ETDEWEB)

    Freifelder, R.; Braun-Munzinger, P.; DeYoung, P.; Schicker, R.; Sen, S.; Stachel, J.

    1987-06-01

    The total capture cross section for the system /sup 32/S+/sup 238/U has been measured at energies from 0.93 to 1.08 times the s-wave interaction barrier by detecting coincident fission fragments following full momentum transfer reactions. The subbarrier cross section cannot be reproduced by a one-dimensional barrier penetration model. Using a quantum mechanical coupled channels model, good agreement is obtained. The measured angular distributions of fission fragments were compared to the predictions of saddle and scission point transition state theory. Saddle point transition state model calculations fail to reproduce the data, while scission point transition state calculations are in agreement with their qualitative trend. Evidence for nonequilibrium processes is presented.

  20. Determination of {sup 238}U and {sup 232}Th in geological samples by alpha and gamma spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Farias, Emerson E.G. de; Hazin, Clovis A., E-mail: chazin@cnen.gov.br [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear; Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil); Honorato, Eliane V.; Franca, Elvis J. De, E-mail: valentim@cnen.gov.br, E-mail: ejfranca@cnen.gov.br [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil)

    2011-07-01

    Alpha and gamma spectrometry are analytical techniques of great importance for the determination of natural radionuclides, especially for radioisotopes of the {sup 238}U and {sup 232}Th series. Due to the presence of completely different chemical elements in these series, with different gamma-ray abundances and decay branches, it is quite relevant to define consistent analytical approaches to be adopted in an environmental analysis routine basis. For the establishment of such protocol for the radiometric analysis of geological samples routinely analyzed in the Environmental Monitoring Division of the Northeastern Regional Center for Nuclear Sciences (CRCN-NE), reference materials of different geologic matrices prepared by the International Atomic Energy Agency - IAEA were analyzed through high resolution gamma-ray spectrometry by means of a Hyper Pure Germanium (HPGe) detector and high resolution alpha spectrometry using a surface barrier detector. Test portions of 2.5 g (for alpha analysis) and 50.0 g (for gamma analysis) of the reference materials IAEA-312 (soil), IAEA-314 (stream sediment), IAEA-375 (soil), and IAEA-135 (sea sediment) were analyzed. The concordance between the obtained values and the reference values for the specific activities of {sup 238}U and {sup 232}Th determined in the certified materials was considered quite satisfactory for both analytical techniques, since the relative errors were lower than 20 %, except for the results of gamma spectrometry using the line 93 keV, in which interference from the 93,35 keV gamma line of {sup 228}Ac (from the {sup 232}Th series) was detected. The results indicated a good degree of comparability for the radiometric analysis of geological samples. (author)

  1. Fission Product Yield Study of 235U, 238U and 239Pu Using Dual-Fission Ionization Chambers

    Science.gov (United States)

    Bhatia, C.; Fallin, B.; Howell, C.; Tornow, W.; Gooden, M.; Kelley, J.; Arnold, C.; Bond, E.; Bredeweg, T.; Fowler, M.; Moody, W.; Rundberg, R.; Rusev, G.; Vieira, D.; Wilhelmy, J.; Becker, J.; Macri, R.; Ryan, C.; Sheets, S.; Stoyer, M.; Tonchev, A.

    2014-05-01

    To resolve long-standing differences between LANL and LLNL regarding the correct fission basis for analysis of nuclear test data [M.B. Chadwick et al., Nucl. Data Sheets 111, 2891 (2010); H. Selby et al., Nucl. Data Sheets 111, 2891 (2010)], a collaboration between TUNL/LANL/LLNL has been established to perform high-precision measurements of neutron induced fission product yields. The main goal is to make a definitive statement about the energy dependence of the fission yields to an accuracy better than 2-3% between 1 and 15 MeV, where experimental data are very scarce. At TUNL, we have completed the design, fabrication and testing of three dual-fission chambers dedicated to 235U, 238U, and 239Pu. The dual-fission chambers were used to make measurements of the fission product activity relative to the total fission rate, as well as for high-precision absolute fission yield measurements. The activation method was employed, utilizing the mono-energetic neutron beams available at TUNL. Neutrons of 4.6, 9.0, and 14.5 MeV were produced via the 2H(d,n)3He reaction, and for neutrons at 14.8 MeV, the 3H(d,n)4He reaction was used. After activation, the induced γ-ray activity of the fission products was measured for two months using high-resolution HPGe detectors in a low-background environment. Results for the yield of seven fission fragments of 235U, 238U, and 239Pu and a comparison to available data at other energies are reported. For the first time results are available for neutron energies between 2 and 14 MeV.

  2. Coupling groundwater residence time and 234U/238U isotopic ratios in a granitic catchment (Vosges, Eastern France)

    Science.gov (United States)

    Viville, Daniel; Aquilina, Luc; Ackerer, Julien; Chatton, Eliot; Labasque, Thierry; Pierret, Marie-Claire; Granet, Mathieu; Perrone, Thierry; Chabaux, François

    2016-04-01

    Weathering processes are active in surface waters but groundwater also represents no neglectable chemical fluxes. As residence-time in groundwater are high, silicate weathering might take place and control Si, Ca and C fluxes. Weathering processes can be deduced from U isotopic ratios but the kinetics of these processes remain relatively poorly constrained. In order to better characterize these processes, we have coupled residence-times deduced from anthropogenic gases (CFC and SF6) analysis and 234U/238U isotopic ratios determination. Samples were collected in the Strengbach catchment (Hydro-geochemical Observatory OHGE, Vosges, eastern France). Two campaigns were carried out in May and August 2015 during two highly contrasted hydro-climatic periods. Both springs and boreholes down to 80 m depth have been sampled. A very clear geochemical distinction is observed between groundwater from surface springs and deeper groundwater from boreholes. Springs show much lower residence-time (few years) and specific chemical composition. Deeper groundwater have residence-time of several decades and different geochemical composition. A clear SF6 production is observed with increasing SF6 concentrations with residence-time. The campaign of May is characterized by highly groundwater levels and spring fluxes. All groundwater show very low residence time, except in the boreholes at depth greater than 40 m. Conversely, during low groundwater-level period in August, the residence times are much higher and CFC concentrations indicate a large mixing process between surface groundwater and deeper levels. The 234U/238U isotopic ratios confirm this vertical zonation in the boreholes, with much higher activity ratios in the deep ground-waters from borehole than in the surface and spring waters; Such high U activity ratios are indicative of long water-rock interactions, which is consistent with the long residence times deducted from the CFC and SF6 data.

  3. Uranium in vitro bioassay action level used to screen workers for chronic inhalation intakes of uranium mill tailings.

    Science.gov (United States)

    Reif, R H; Turner, J B; Carlson, D S

    1992-10-01

    A uranium in vitro bioassay (urinalysis) action level was derived for use at the Department of Energy's Uranium Mill Tailings Remedial Action Project sites to identify chronic inhalation intakes of uranium mill tailings causing 0.5 mSv (50 mrem) annual effective dose equivalent. All radionuclides in the 238U decay chain that contribute 1% or more to the annual effective dose equivalent from an inhalation intake of uranium mill tailings were included in the derivation of the urinalysis action level. Using a chronic inhalation intake model, the uranium urinalysis action level for a 24-h urine sample, collected on a quarterly schedule, was calculated to be 1.5 micrograms.

  4. Spectral interference corrections for the measurement of {sup 238}U in materials rich in thorium by a high resolution {gamma}-ray spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Yuecel, H. [Turkish Atomic Energy Authority (TAEA), Besevler Yerleskesi, Tandogan, 06100 Ankara (Turkey)], E-mail: alfa.haluky@gmail.com; Solmaz, A.N.; Koese, E.; Bor, D. [Institute of Nuclear Sciences of Ankara University (AU-INS), Tandogan, 06100 Ankara (Turkey)

    2009-11-15

    In this study, the spectral interferences are investigated for the analytical peaks at 63.3 keV of {sup 234}Th and 1001.0 keV of {sup 234m}Pa, which are often used in the measurement of {sup 238}U activity by the {gamma}-ray spectrometry. The correction methods are suggested to estimate the net peak areas of the {gamma}-rays overlapping the analytical peaks, due to the contribution of {sup 232}Th that may not be negligible in materials rich in natural thorium. The activity results for the certified reference materials (CRMs) containing U and Th were measured with a well type Ge detector. The self-absorption and true coincidence-summing (TCS) effects were also taken into account in the measurements. It is found that ignoring the contributions of the interference {gamma}-rays of {sup 232}Th and {sup 235}U to the mixed peak at 63.3 keV of {sup 234}Th ({sup 238}U) leads to the remarkably large systematic influence of 0.8-122% in the measured {sup 238}U activity, but in case of ignoring the contribution of {sup 232}Th via the interference {gamma}-ray at 1000.7 keV of {sup 228}Ac to the mixed peak at 1001 keV of {sup 234m}Pa ({sup 238}U) results in relatively smaller systematic influence of 0.05-3%, depending on thorium contents in the samples. The present results showed that the necessary correction for the spectral interferences besides self-absorption and TCS effects is also very important to obtain more accurate {sup 238}U activity results. Additionally, if one ignores the contribution of {sup 232}Th to both {sup 238}U and {sup 40}K activities in materials, the maximum systematic influence on the effective radiation dose is estimated to be {approx}6% and {approx}1% via the analytical peaks at 63.3 and 1001 keV for measurement of the {sup 238}U activity, respectively.

  5. Preliminary concepts: coordinated safeguards for materials management in a thorium--uranium fuel reprocessing plant

    Energy Technology Data Exchange (ETDEWEB)

    Hakkila, E.A.; Barnes, J.W.; Dayem, H.A.; Dietz, R.J.; Shipley, J.P.

    1978-10-01

    This report addresses preliminary concepts for coordinated safeguards materials management in a typical generic thorium--uranium-fueled light-water reactor (LWR) fuels reprocessing plant. The reference facility is designed to recover thorium and uranium from first-generation (denatured /sup 235/U) startup fuels, first-recycle and equilibrium (denatured /sup 233/U) thorium--uranium LWR fuels, and to recover the plutonium generated in the /sup 238/U denaturant as well. 12 figures, 3 tables.

  6. Influences of parameter uncertainties within the ICRP-66 respiratory tract model: regional tissue doses for 239PuO2 and 238UO2/238U3O8.

    Science.gov (United States)

    Farfán, Eduardo B; Huston, Thomas E; Bolch, W Emmett; Vernetson, William G; Bolch, Wesley E

    2003-04-01

    This paper extends an examination of the influence of parameter uncertainties on regional doses to respiratory tract tissues for short-ranged alpha particles using the ICRP-66 respiratory tract model. Previous papers examined uncertainties in the deposition and clearance aspects of the model. The critical parameters examined in this study included target tissue depths, thicknesses, and masses, particularly within the thoracic or lung regions of the respiratory tract. Probability density functions were assigned for the parameters based on published data. The probabilistic computer code LUDUC (Lung Dose Uncertainty Code) was used to assess regional and total lung doses from inhaled aerosols of 239PuO2 and 238UO2/238U3O8. Dose uncertainty was noted to depend on the particle aerodynamic diameter. Additionally, dose distributions were found to follow a lognormal distribution pattern. For 239PuO2 and 238UO2/238U3O8, this study showed that the uncertainty in lung dose increases by factors of approximately 50 and approximately 70 for plutonium and uranium oxides, respectively, over the particle size range from 0.1 to 20 microm. For typical exposure scenarios involving both radionuclides, the ratio of the 95% dose fractile to the 5% dose fractile ranged from approximately 8-10 (corresponding to a geometric standard deviation, or GSD, of about 1.7-2) for particle diameters of 0.1 to 1 microm. This ratio increased to about 370 for plutonium oxide (GSD approximately 4.5) and to about 600 for uranium oxide (GSD approximately 5) as the particle diameter approached 20 microm. However, thoracic tissue doses were quite low at larger particle sizes because most of the deposition occurred in the extrathoracic airways. For 239PuO2, median doses from LUDUC were found be in general agreement with those for Reference Man (via deterministic LUDEP 2.0 calculations) in the particle range of 0.1 to 5 microm. However, median doses to the basal cell nuclei of the bronchial airways (BB

  7. The uranium behaviour during rock-water interaction in the granites from the Itu complex (Sao Paulo, Brazil): a laboratory study

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Helen S.B. da; Marques, Leila S.; Kawauchi, Roberto K., E-mail: leila@iag.usp.br, E-mail: keiji@iag.usp.br [Instituto de Astronomia, Geofisica e Ciencias Atmosfericas. Universidade de Sao Paulo (USP), SP (Brazil)

    2011-07-01

    In order to elucidate the mechanisms involved in the process of uranium leaching due to the rock-water interaction in the granitic rocks from Itu Complex (Sao Paulo, Brazil), an experimental arrangement was developed and built. About 2.5kg of crushed rock fragments from Cabreuva and Indaiatuba Intrusions were maintained at room temperature within a glass flask filled with circulating water. The percolating water was removed periodically (from 10 to 30 days) for uranium analysis and then replaced by an equal volume of fresh water. Alpha spectrometry was used to determine the activity concentrations of {sup 234}U and {sup 238}U, and {sup 234}U/{sup 238}U activity ratios, of the waters as well as of the granites. The results for both samples showed that most of the uranium is leached in the first days after the contact between rock and water. The {sup 234}U/{sup 238}U activity ratios were significantly greater than unity, indicating radioactive disequilibrium between those isotopes, probably due to alpha recoil. Although the uranium activity concentrations in the water samples diminished with the increasing of time, it was not observed considerable variations of the {sup 234}U/{sup 238}U activity ratios. It was also noticed that, the amount of leached uranium as well as the {sup 234}U/{sup 238}U activity ratios are characteristics of each sample submitted to leaching, reflecting the differences of the granite facies mineralogy.(author)

  8. Depleted uranium analysis in blood by inductively coupled plasma mass spectrometry

    Science.gov (United States)

    Todorov, T.I.; Xu, H.; Ejnik, J.W.; Mullick, F.G.; Squibb, K.; McDiarmid, M.A.; Centeno, J.A.

    2009-01-01

    In this study we report depleted uranium (DU) analysis in whole blood samples. Internal exposure to DU causes increased uranium levels as well as change in the uranium isotopic composition in blood specimen. For identification of DU exposure we used the 235U/238U ratio in blood samples, which ranges from 0.00725 for natural uranium to 0.002 for depleted uranium. Uranium quantification and isotopic composition analysis were performed by inductively coupled plasma mass spectrometry. For method validation we used eight spiked blood samples with known uranium concentrations and isotopic composition. The detection limit for quantification was determined to be 4 ng L-1 uranium in whole blood. The data reproduced within 1-5% RSD and an accuracy of 1-4%. In order to achieve a 235U/238U ratio range of 0.00698-0.00752% with 99.7% confidence limit a minimum whole blood uranium concentration of 60 ng L??1 was required. An additional 10 samples from a cohort of veterans exposed to DU in Gulf War I were analyzed with no knowledge of their medical history. The measured 235U/ 238U ratios in the blood samples were used to identify the presence or absence of DU exposure within this patient group. ?? 2009 The Royal Society of Chemistry.

  9. Neutron capture cross section measurements of $^{238}$U, $^{241}$Am and $^{243}$Am at n_TOF

    CERN Multimedia

    Koehler, P E; Plag, R

    The increase of the world energy demand and the need of low carbon energy sources have triggered the renaissance and/or enhancement of nuclear energy in many countries. Fundamental nuclear physics can contribute in a practical way to the sustainability and safety of the nuclear energy production and the management of the nuclear waste. There exists a series of recent studies which address the most relevant isotopes, decay data, nuclear reaction channels and energy ranges which have to be investigated in more detail for improving the design of different advanced nuclear systems [1] and nuclear fuel cycles [2]. In this proposal, we aim at the measurement of the neutron capture cross sections of $^{238}$U, $^{241}$Am and $^{243}$Am. All three isotopes are listed in the NEA High Priority Request List [37], are recommended for measurements [1] and play an important role in the nuclear energy production and fuel cycle scenarios. The measurements will provide as well valuable nuclear structure data necessary for the...

  10. Gamma-Ray Emission Spectra as a Constraint on Calculations of 234 , 236 , 238U Neutron-Capture Cross Sections

    Science.gov (United States)

    Ullmann, J. L.; Krticka, M.; Kawano, T.; Bredeweg, T. A.; Baramsai, B.; Couture, A.; Haight, R. C.; Jandel, M.; Mosby, S.; O'Donnell, J. M.; Rundberg, R. S.; Vieira, D. J.; Wilhelmy, J. B.; Becker, J. A.; Wu, C. Y.; Chyzh, A.

    2015-10-01

    Calculations of the neutron-capture cross section at low neutron energies (10 eV through 100's of keV) are very sensitive to the nuclear level density and radiative strength function. These quantities are often poorly known, especially for radioactive targets, and actual measurements of the capture cross section are usually required. An additional constraint on the calculation of the capture cross section is provided by measurements of the cascade gamma spectrum following neutron capture. Recent measurements of 234 , 236 , 238U(n, γ) emission spectra made using the DANCE 4 π BaF2 array at the Los Alamos Neutron Science Center will be presented. Calculations of gamma-ray spectra made using the DICEBOX code and of the capture cross section made using the CoH3 code will also be presented. These techniques may be also useful for calculations of more unstable nuclides. This work was performed with the support of the U.S. Department of Energy, National Nuclear Security Administration by Los Alamos National Security, LLC (Contract DE-AC52-06NA25396) and Lawrence Livermore National Security, LLC (Contract DE-AC52-07NA2734).

  11. Fission-fragment properties in 238U(n ,f ) between 1 and 30 MeV

    Science.gov (United States)

    Duke, D. L.; Tovesson, F.; Laptev, A. B.; Mosby, S.; Hambsch, F.-J.; Bryś, T.; Vidali, M.

    2016-11-01

    The fragment mass and kinetic energy in neutron-induced fission of 238U has been measured for incident energies from 1 to 30 MeV at the Los Alamos Neutron Science Center. The change in mass distributions over this energy range were studied, and the transition from highly asymmetric to more symmetric mass distributions is observed. A decrease in average total kinetic energy (TKE ¯) with increasing excitation energy is observed, consistent with previous experimental work. Additional structure at multichance fission thresholds is present in the TKE ¯ data. The correlations between fragment masses and total kinetic energy and how that changes with excitation energy of the fissioning compound nucleus were also measured. The fission mass yields and average total kinetic energy are important for fission-based technologies such as nuclear reactors to understand nuclear waste generation and energy output when developing new and advanced concepts. The correlations between fragment mass and kinetic energy are needed both as input for theoretical calculations of the deexcitation process in fission fragments by prompt radiation emission and for validating advanced theoretical fission models describing the formation of the primordial fragments.

  12. Photo-fission Product Yield Measurements at Eγ=13 MeV on 235U, 238U, and 239Pu

    Science.gov (United States)

    Tornow, W.; Bhike, M.; Finch, S. W.; Krishichayan, Fnu; Tonchev, A. P.

    2016-09-01

    We have measured Fission Product Yields (FPYs) in photo-fission of 235U, 238U, and 239Pu at TUNL's High-Intensity Gamma-ray Source (HI γS) using mono-energetic photons of Eγ = 13 MeV. Details of the experimental setup and analysis procedures will be discussed. Yields for approximately 20 fission products were determined. They are compared to neutron-induced FPYs of the same actinides at the equivalent excitation energies of the compound nuclear systems. In the future photo-fission data will be taken at Eγ = 8 . 0 and 10.5 MeV to find out whether photo-fission exhibits the same so far unexplained dependence of certain FPYs on the energy of the incident probe, as recently observed in neutron-induced fission, for example, for the important fission product 147Nd. Work supported by the U. S. Dept. of Energy, under Grant No. DE-FG02-97ER41033, and by the NNSA, Stewardship Science Academic Alliances Program, Grant No. DE-NA0001838 and the Lawrence Livermore, National Security, LLC under Contract No. DE-AC52-07NA27344.

  13. Uranium isotope evidence for temporary ocean oxygenation in the aftermath of the Sturtian Snowball Earth

    Science.gov (United States)

    Lau, Kimberly V.; Macdonald, Francis A.; Maher, Kate; Payne, Jonathan L.

    2017-01-01

    The appearance and radiation of animals are commonly attributed to Neoproterozoic oceanic oxygenation, yet independent geochemical evidence for such an event remains equivocal. Strata deposited between the Sturtian and Marinoan Snowball Earth glaciations (660 to 640 Ma) contain the earliest animal biomarkers and possible body fossils. To quantify the extent of seafloor oxygenation during this critical interval, we present uranium isotope ratios (238U/235U denoted as δ238 U) from limestone of the Taishir Formation in Mongolia through two stratigraphic sections that are separated by ∼75 km within the same depositional basin. Above the Sturtian glacial deposits, through ∼150 m of stratigraphy, δ238 U compositions have a mean value of -0.47‰. This interval is followed by a ∼0.3‰ decrease in δ238 U, coincident with the Taishir negative carbon isotope excursion. Thereafter, δ238 U values remain relatively low until the erosional unconformity at the base of the Marinoan glacial deposits. Using a box model, we show that the best explanation for the higher δ238 U values of the post-Sturtian limestones is extensive-but temporary-oxygenation of the seafloor, and is inconsistent with a scenario involving only increased delivery of uranium to the oceans due to post-Snowball weathering. The decline in δ238 U in overlying strata, coincident with the Taishir negative δ13 C excursion, indicates a subsequent decrease in seafloor oxygenation. The U isotopic data, combined with modeling results, challenge the notion of a simple, unidirectional oxygenation of Neoproterozoic oceans.

  14. Activity concentrations of {sup 238}U and {sup 226}Ra in scales formed on pipes of industrial boilers in the state of Pernambuco, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Poggi, Claudia M.B.; Farias, Emerson E.G. de, E-mail: claudiapoggi04@gmail.com, E-mail: emersonemiliano@yahoo.com.br [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Departamento de Energia Nuclear; Franca, Elvis J.; Hazin, Clovis A., E-mail: chazin@cnen.gov.br [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil); Gazineu, Maria H.P., E-mail: helena@unicap.br [Universidade Catolica de Pernambuco (UNICAP), Recife, PE (Brazil). Centro de Ciencias e Tecnologia

    2015-07-01

    The procedures employed in the industry can generate significant amounts of solid, liquid and gaseous wastes that usually contain toxic or materials of difficulty degradation. One of the facts that contribute to the formation of such wastes is the generation of steam used in operating processes and industry segments. Currently, steam supplied by boilers is the most economical and practical mode of heat transfer in industrial processes. Due to the high temperature of water used in these processes, compounds which were previously soluble become insoluble, generating residues called scales. This material, which contains stable ions, can also present naturally occurring radionuclides such as {sup 238}U and {sup 226}Ra, which concentrate over time in piping and equipment surfaces. If not disposed correctly, this material also can contaminate the environment. The main origin of these radionuclides is the use of groundwater in industrial processes. Thus, in regions of naturally enriched in radionuclides such as the Region of Pernambuco, including the municipalities of Paulista and Goiana, there is a greater possibility of radioactive scale formation. Therefore, this study aimed to determine the activity concentrations of {sup 238}U and {sup 226}Ra present in the solid wastes generated by industries situated in Paulista and Goiana, in order to assess radionuclide disequilibrium. For the sake of comparison, scale samples collected from industries located in the municipality of Caruaru, far from the previous municipalities, were also analyzed. The determination of the activity concentrations for {sup 238}U and {sup 226}Ra was performed by High Resolution Gamma-Ray Spectrometry. Samples were collected, prepared, packed in plastic containers and set aside for a minimum time of 21 days, for the secular equilibrium to occur between {sup 226}Ra and its short lived descendants. The counting time was 80,000 seconds. Gamma energies used for determination of activity concentrations

  15. Uranium isotopes in carbonate aquifers of arid region setting

    DEFF Research Database (Denmark)

    Alshamsi, Dalal M.; Murad, Ahmed A.; Aldahan, Ala

    2013-01-01

    Groundwater in arid and semiarid regions is vital resource for many uses and therefore information about concentrations of uranium isotopes among other chemical parameters are necessary. In the study presented here, distribution of 238U and 235U in groundwater of four selected locations in the so......Groundwater in arid and semiarid regions is vital resource for many uses and therefore information about concentrations of uranium isotopes among other chemical parameters are necessary. In the study presented here, distribution of 238U and 235U in groundwater of four selected locations...... in the southern Arabian peninsula, namely at two locations within the United Arab Emirates (UAE) and two locations in Oman are discussed. The analyses of the uranium isotopes were performed using ICP-MS and the results indicated a range of concentrations for 235U and 238 U at 3–39 ng L-1 (average: 18 ng L-1......) and 429–5,293 ng L-1 (average: 2,508 ng L-1) respectively. These uranium concentrations are below the higher permissible WHO limit for drinking water and also comparable to averages found in groundwater from similar aquifers in Florida and Tunisia. Negative correlation between rainfall and uranium...

  16. The distribution of depleted uranium contamination in Colonie, NY, USA

    Energy Technology Data Exchange (ETDEWEB)

    Lloyd, N.S., E-mail: nsl3@alumni.leicester.ac.uk [Department of Geology, University of Leicester, University Road, Leicester, LE1 7RH (United Kingdom); Chenery, S.R.N. [British Geological Survey, Kingsley Dunham Centre, Keyworth, Nottingham, NG12 5GG (United Kingdom); Parrish, R.R. [Department of Geology, University of Leicester, University Road, Leicester, LE1 7RH (United Kingdom); NERC Isotope Geosciences Laboratory, Kingsley Dunham Centre, Keyworth, Nottingham, NG12 5GG (United Kingdom)

    2009-12-20

    Uranium oxide particles were dispersed into the environment from a factory in Colonie (NY, USA) by prevailing winds during the 1960s and '70s. Uranium concentrations and isotope ratios from bulk soil samples have been accurately measured using inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) without the need for analyte separation chemistry. The natural range of uranium concentrations in the Colonie soils has been estimated as 0.7-2.1 {mu}g g{sup -1}, with a weighted geometric mean of 1.05 {mu}g g{sup -1}; the contaminated soil samples comprise uranium up to 500 {+-} 40 {mu}g g{sup -1}. A plot of {sup 236}U/{sup 238}U against {sup 235}U/{sup 238}U isotope ratios describes a mixing line between natural uranium and depleted uranium (DU) in bulk soil samples; scatter from this line can be accounted for by heterogeneity in the DU particulate. The end-member of DU compositions aggregated in these bulk samples comprises (2.05 {+-} 0.06) x 10{sup -3235}U/{sup 238}U, (3.2 {+-} 0.1) x 10{sup -5236}U/{sup 238}U, and (7.1 {+-} 0.3) x 10{sup -6234}U/{sup 238}U. The analytical method is sensitive to as little as 50 ng g{sup -1} DU mixed with the natural uranium occurring in these soils. The contamination footprint has been mapped northward from site, and at least one third of the uranium in a soil sample from the surface 5 cm, collected 5.1 km NNW of the site, is DU. The distribution of contamination within the surface soil horizon follows a trend of exponential decrease with depth, which can be approximated by a simple diffusion model. Bioturbation by earthworms can account for dispersal of contaminant from the soil surface, in the form of primary uranium oxide particulates, and uranyl species that are adsorbed to organic matter. Considering this distribution, the total mass of uranium contamination emitted from the factory is estimated to be c. 4.8 tonnes.

  17. Isotope ratio measurement of uranium in safeguards environmental samples by inductively-coupled plasma mass spectrometry (ICP-MS)

    Energy Technology Data Exchange (ETDEWEB)

    Magara, Masaaki; Sakakibara, Takaaki; Kurosawa, Setsumi; Takahashi, Masato; Sakurai, Satoshi; Hanzawa, Yukiko; Esaka, Fumitaka; Watanabe, Kazuo; Usuda, Shigekazu [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2002-04-01

    In order to measure isotope ratio of uranium in safeguards environmental samples with ICP-MS precisely, production of polyatomic ions of IrAr, PtAr and AuAr was measured and mass bias of ICP-MS is investigated by using isotopic standards of uranium and lead. The intensities of IrAr, PtAr and AuAr relative to the atomic ions were found to be 1.8 x 10{sup -6}, 1.6 x 10{sup -5} and 4.1 x 10{sup -5}, respectively. The production of {sup 193}Ir{sup 40}Ar is too small to interfere with the measurement of {sup 233}U, if the concentration of Ir is the same level as that of {sup 233}U. However, there is possibility that the presence of Pt and Au interferes with the measurement of minor isotopes of uranium and {sup 237}Np. On the other hand, the mass biases of {sup 235}U/{sup 238}U and {sup 208}Pb/{sup 206}Pb were measured with the parameter of {sup 238}U{sup 16}O/{sup 238}U. Since unexpected change of the mass bias during measurements causes frequently erroneous results, the monitoring of {sup 238}U{sup 16}O/{sup 238}U is effective for the precise isotope ratio measurement. (author)

  18. 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)

  19. Internal tides and sediment dynamics in the deep sea—Evidence from radioactive 234Th/ 238U disequilibria

    Science.gov (United States)

    Turnewitsch, Robert; Reyss, Jean-Louis; Nycander, Jonas; Waniek, Joanna J.; Lampitt, Richard S.

    2008-12-01

    Residual flow, barotropic tides and internal (baroclinic) tides interact in a number of ways with kilometer-scale seafloor topography such as abyssal hills and seamounts. Because of their likely impact on vertical mixing such interactions are potentially important for ocean circulation and the mechanisms and the geometry of these interactions are a matter of ongoing studies. In addition, very little is known about how these interactions are reflected in the sedimentary record. This multi-year study investigates if flow/topography interactions are reflected in distributional patterns of the natural short-lived (half-life: 24.1 d) particulate-matter tracer 234Th relative to its conservative (non-particle-reactive) and very long-lived parent nuclide 238U. The sampling sites were downstream of, or surrounded by, fields of short seamounts and, therefore, very likely to be influenced by nearby flow/topography interactions. At the sampling sites between about 200 and 1000 m above the seafloor recurrent 'fossil' disequilibria were detected. 'Fossil' disequilibria are defined by clearly detectable 234Th/ 238U disequilibria (total 234Th radioactivity radioactivity, indicating a history of intense particulate 234Th scavenging and particulate-matter settling from the sampled parcel of water) and conspicuously low particle-associated 234Th activities. 'Fossil' disequilibria were centered at levels in the water column that correspond to the average height of the short seamounts near the sampling sites. This suggests the 'fossil' disequilibria are formed on the seamount slopes. Moreover, the magnitude of the 'fossil' disequilibria suggests that the slopes of the short seamounts in the study region are characterized by particularly vigorous fluid dynamics. Since 'fossil' disequilibria already occurred at ˜ O(1-10 km) away from the seamount slopes it is likely that these vigorous fluid dynamics rapidly decay away from the slopes on scales of O(1-10 km). These conclusions are

  20. Low-energy fission investigated in reactions of 750 AMeV {sup 238}U-ions with Pb and Be targets. Pt. 1. Nuclear charge distributions

    Energy Technology Data Exchange (ETDEWEB)

    Armbruster, P. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Bernas, M. [IPN Orsay, 91 Orsay (France); Czajkowski, S. [IPN Orsay, 91 Orsay (France); Geissel, H. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Aumann, T. [Mainz Univ. (Germany). Inst. fuer Kernchemie; Dessagne, P. [Strasbourg-1 Univ., 67 (France). Centre de Recherches Nucleaires; Donzaud, C. [IPN Orsay, 91 Orsay (France); Hanelt, E. [Technische Hochschule Darmstadt (Germany). Inst. fuer Kernphysik; Heinz, A. [Technische Hochschule Darmstadt (Germany). Inst. fuer Kernphysik; Hesse, M. [Tuebingen Univ. (Germany). Physikalisches Inst.; Kozhuharov, C. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Miehe, C. [Strasbourg-1 Univ., 67 (France). Centre de Recherches Nucleaires; Muenzenberg, G. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Pfuetzner, M. [Warsaw Univ. (Poland); Schmidt, K.H. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Schwab, W. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Stephan, C. [IPN Orsay, 91 Orsay (France); Suemmerer, K. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Tassan-got, L. [IPN Orsay, 91 Orsay (France); Voss, B. [Technische Hochschule Darmstadt (Germany). Inst. fuer Kernphysik

    1996-07-01

    Charge distributions of fragments from low energy nuclear fission are investigated in reactions of highly fissile {sup 238}U projectiles at relativistic energies (750 A.MeV) with a heavy (Pb) and a light (Be) target. The fully stripped fission fragments are separated by the fragment separator (FRS). Their high kinetic energies in the laboratory system allow the identification of all atomic numbers by using multiple-sampling ionization chambers (MUSIC). The elemental distributions of fragments observed at larger magnetic rigidities than the {sup 238}U projectiles show asymmetric break-up and odd-even effects. They indicate a low energy fission process, induced mainly by dissociation in the electro-magnetic field for the U/Pb-system, or by peripheral nuclear interactions for the U/Be-system. (orig.)

  1. Low energy fission investigated in reactions of 750 AMeV {sup 238}U-ions with Pb and Be targets

    Energy Technology Data Exchange (ETDEWEB)

    Armbruster, P. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Bernas, M. [Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire; Czajkowski, S. [Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire; Geissel, H. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Aumann, T. [Mainz Univ. (Germany). Inst. fuer Kernchemie; Dessagne, P. [Strasbourg-1 Univ., 67 (France). Centre de Recherches Nucleaires; Donzaud, C. [Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire; Hanelt, E. [Technische Hochschule Darmstadt (Germany). Inst. fuer Kernphysik; Heinz, A. [Technische Hochschule Darmstadt (Germany). Inst. fuer Kernphysik; Hesse, M. [Tuebingen Univ. (Germany). Physikalisches Inst.; Kozhuharov, C. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Miehe, C. [Strasbourg-1 Univ., 67 (France). Centre de Recherches Nucleaires; Muenzenberg, G. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Pfuetzner, M. [Warsaw Univ. (Poland); Schmidt, K.H. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Schwab, W. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Stephan, C. [Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire; Suemmerer, K. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Tassan-Got, L. [Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire; Voss, B. [Technische Hochschule Darmstadt (Germany). Inst. fuer Kernphysik

    1995-10-01

    Charge distributions of fragments from low energy nuclear fission are investigated in reactions of highly fissile {sup 238}U projectiles at relativistic energies (750 AMeV) with a heavy (Pb) and a light (Be) target. The fully stripped fission fragments are separated by the Fragment Separator (FRS). Their high kinetic energies in the laboratory system allow the identification of all atomic numbers by using Multiple-Sample Ionization Chambers (MUSIC). The elemental distributions of fragments observed at larger magnetic rigidities than the {sup 238}U projectiles show asymmetric break-up and odd-even effects. They indicate a low energy fission process, induced mainly by dissociation in the electromagnetic field for the U/Pb-system, or by peripheral nuclear interactions for the U/Be-system. (orig.)

  2. Low-energy fission investigated in reactions of 750 AMeV238U-ions with Pb and Be targets. I. Nuclear charge distributions

    Science.gov (United States)

    Armbruster, P.; Bernas, M.; Czajkowski, S.; Geissel, H.; Aumann, T.; Dessagne, Ph.; Donzaud, C.; Hanelt, E.; Heinz, A.; Hesse, M.; Kozhuharov, C.; Miehe, Ch.; Münzenberg, G.; Pfützner, M.; Schmidt, K.-H.; Schwab, W.; Stéphan, C.; Sümmerer, K.; Tassan-Got, L.; Voss, B.

    1996-12-01

    Charge distributions of fragments from low energy nuclear fission are investigated in reactions of highly fissile238U projectiles at relativistic energies (750 A·MeV) with a heavy (Pb) and a light (Be) target. The fully stripped fission fragments are separated by the Fragment Separator (FRS). Their high kinetic energies in the laboratory system allow the identification of all atomic numbers by using Multiple-Sampling Ionization Chambers (MUSIC). The elemental distributions of fragments observed at larger magnetic rigidities than the238U projectiles show asymmetric break-up and odd-even effects. They indicate a low energy fission process, induced mainly by dissociation in the electro-magnetic field for the U/Pb-system, or by peripheral nuclear interactions for the U/Be-system.

  3. A beta-alpha coincidence counting system for measurement of trace quantities of 238U and 232Th in aqueous samples at the Sudbury Neutrino Observatory.

    Science.gov (United States)

    Dawson, M.; Doucas, G.; Fergani, H.; Jelley, N. A.; Majerus, S.; O'Keeffe, H. M.; Peeters, S. J. M.; Perry, C.

    2016-08-01

    The Sudbury Neutrino Observatory experiment was built to measure the total flux of 8B solar neutrinos via the neutral current disintegration deuterium nuclei. This process can be mimiced by daughter isotopes of 232Th and 238U which can photodisintegrate the deuterium nucleus. Measurement of the concentration of such radioisotopes in the heavy water was critical to the success of the experiment. A radium assay technique using Hydrous Titanium Oxide coated filters was developed for this purpose and it was used in conjunction with a delayed beta-alpha coincidence counting system. The design, calibration and operation of this counting system are described in this paper. The counting efficiency for 232Th (224Ra) and 238U (226Ra) were measured to be 50 ± 5% and 62 ± 7%

  4. Towards the high-accuracy determination of the 238U fission cross section at the threshold region at CERN – n_TOF

    Directory of Open Access Journals (Sweden)

    Diakaki M.

    2016-01-01

    Full Text Available The 238U fission cross section is an international standard beyond 2 MeV where the fission plateau starts. However, due to its importance in fission reactors, this cross-section should be very accurately known also in the threshold region below 2 MeV. The 238U fission cross section has been measured relative to the 235U fission cross section at CERN – n_TOF with different detection systems. These datasets have been collected and suitably combined to increase the counting statistics in the threshold region from about 300 keV up to 3 MeV. The results are compared with other experimental data, evaluated libraries, and the IAEA standards.

  5. Study of the 238U(d,p) surrogate reaction via the simultaneous measurement of gamma-decay and fission probabilities

    CERN Document Server

    Ducasse, Q; Aïche, M; Marini, P; Mathieu, L; Görgen, A; Guttormsen, M; Larsen, A C; Tornyi, T; Wilson, J N; Barreau, G; Boutoux, G; Czajkowski, S; Giacoppo, F; Gunsing, F; Hagen, T W; Lebois, M; Lei, J; Méot, V; Morillon, B; Moro, A; Renstrøm, T; Roig, O; Rose, S J; Sérot, O; Siem, S; Tsekhanovich, I; Tveten, G M; Wiedeking, M

    2015-01-01

    We investigated the 238U(d,p) reaction as a surrogate for the n + 238U reaction. For this purpose we measured for the first time the gamma-decay and fission probabilities of 239U* simultaneously and compared them to the corresponding neutron-induced data. We present the details of the procedure to infer the decay probabilities, as well as a thorough uncertainty analysis, including parameter correlations. Calculations based on the continuum-discretized coupled-channels and distorted-wave Born approximations were used to correct our data from detected protons originating from elastic and inelastic deuteron breakup. The corrected fission probability is in agreement with neutron-induced data, whereas the gamma-decay probability is much higher than the neutron-induced data. The performed statistical-model calculations are not able to explain these results.

  6. Measurement of nuclides of uranium and thorium series of disequilibrium using γ-spectroscopy

    Institute of Scientific and Technical Information of China (English)

    刘广山; 黄奕普; 李静; 叶林

    2002-01-01

    The decay dynamic equations of two daughters were resolved as initial activities of daughters are not zero, and gave calculation formula of activities for measuring uranium and thorium series of disequilibrium using γ-spectroscopy. 238U, 234Th, 226Ra, 222Rn, 228Ra, 228Th, 224Ra, 212pb, 210pb and 40K in two sediment samples were determined as application.

  7. Determination of the isotopic composition of natural and slightly enriched uranium by alpha-spectrometry

    DEFF Research Database (Denmark)

    Kunzendorf, Helmar

    1968-01-01

    Determinations of the isotope contents of 238U, 235U and 234U in five uranium samples containing 0–5 at% 235U were carried out on the basis of a least-squares fit of the α-spectra from the samples, measured with a semiconductor detector, to the theoretically expected α-spectra. With a simple source...

  8. Distribution of uranium, thorium, and isotopic composition of uranium in soil samples of south Serbia: Evidence of depleted uranium

    Directory of Open Access Journals (Sweden)

    Sahoo Sarata Kumar

    2004-01-01

    Full Text Available Inductively coupled plasma mass spectrometry and thermal ionization mass spectrom - etry were used to measure concentration of uranium and thorium as well as isotopic composition of uranium respectively in soil samples collected around south Serbia. An analytical method was established for a routine sample preparation procedure for uranium and thorium. Uranium was chemically separated and purified from soil samples by anion exchange resin and UTEVA extraction chromatography and its isotopic composition was measured using a thermal ionization mass spectrometry. There was a little deviation of U/Th ratio from the average values in some soil samples. Presence of 236U as well as depleted uranium was observed in 235U/238U ratio measurement in the same soil sample.

  9. The Chemistry and Toxicology of Depleted Uranium

    Directory of Open Access Journals (Sweden)

    Sidney A. Katz

    2014-03-01

    Full Text Available Natural uranium is comprised of three radioactive isotopes: 238U, 235U, and 234U. Depleted uranium (DU is a byproduct of the processes for the enrichment of the naturally occurring 235U isotope. The world wide stock pile contains some 1½ million tons of depleted uranium. Some of it has been used to dilute weapons grade uranium (~90% 235U down to reactor grade uranium (~5% 235U, and some of it has been used for heavy tank armor and for the fabrication of armor-piercing bullets and missiles. Such weapons were used by the military in the Persian Gulf, the Balkans and elsewhere. The testing of depleted uranium weapons and their use in combat has resulted in environmental contamination and human exposure. Although the chemical and the toxicological behaviors of depleted uranium are essentially the same as those of natural uranium, the respective chemical forms and isotopic compositions in which they usually occur are different. The chemical and radiological toxicity of depleted uranium can injure biological systems. Normal functioning of the kidney, liver, lung, and heart can be adversely affected by depleted uranium intoxication. The focus of this review is on the chemical and toxicological properties of depleted and natural uranium and some of the possible consequences from long term, low dose exposure to depleted uranium in the environment.

  10. Fission Product Yields from 232Th, 238U, and 235U Using 14 MeV Neutrons

    Science.gov (United States)

    Pierson, B. D.; Greenwood, L. R.; Flaska, M.; Pozzi, S. A.

    2017-01-01

    Neutron-induced fission yield studies using deuterium-tritium fusion-produced 14 MeV neutrons have not yet directly measured fission yields from fission products with half-lives on the order of seconds (far from the line of nuclear stability). Fundamental data of this nature are important for improving and validating the current models of the nuclear fission process. Cyclic neutron activation analysis (CNAA) was performed on three actinide targets-thorium-oxide, depleted uranium metal, and highly enriched uranium metal-at the University of Michigan's Neutron Science Laboratory (UM-NSL) using a pneumatic system and Thermo-Scientific D711 accelerator-based fusion neutron generator. This was done to measure the fission yields of short-lived fission products and to examine the differences between the delayed fission product signatures of the three actinides. The measured data were compared against previously published results for 89Kr, -90, and -92 and 138Xe, -139, and -140. The average percent deviation of the measured values from the Evaluated Nuclear Data Files VII.1 (ENDF/B-VII.1) for thorium, depleted-uranium, and highly-enriched uranium were -10.2%, 4.5%, and -12.9%, respectively. In addition to the measurements of the six known fission products, 23 new fission yield measurements from 84As to 146La are presented.

  11. Evaluation of the Homogeneity of the Uranium Isotope Composition of NIST SRM 610/611 by MC-ICP-MS, MC-TIMS, and SIMS

    Directory of Open Access Journals (Sweden)

    Mindy M. Zimmer

    2014-06-01

    Full Text Available As analytical and microanalytical applications employing uranium isotope ratios increase, so does the need for reliable reference materials, particularly in the fields of geochemistry, geochronology, and nuclear forensics. We present working values for uranium isotopic data of NIST 610/611 glass, collected by multicollector inductively-coupled plasma mass spectrometry (MC-ICP-MS, multicollector thermal ionization mass spectrometry (MC-TIMS, and secondary ion mass spectrometry (SIMS. The presence of depleted U, and, in this case, measureable 236U, makes NIST 610/611 an ideal candidate for a uranium isotopic reference material for nuclear materials. We analyzed multiple chips of three different NIST 611 wafers and found no heterogeneity in 234U/238U, 235U/238U, and 236U/238U within or between the wafers, within analytical uncertainty. We determined working values and uncertainties (using a coverage factor of two using data from this study and the literature for the following U isotope ratios: 234U/238U = 9.45 × 10−6 ± 5.0 × 10−8; 235U/238U = 2.38555 × 10−3 ± 4.7 × 10−7; and 236U/238U = 4.314 × 10−5 ± 4.0 × 10−8. SIMS data show 235U/238U is reproducible to within 1% (within analytical uncertainty in a single wafer, at a scale of 25 μm. Multiple studies have demonstrated homogeneity between wafers of NIST 610 and NIST 611, thus the data reported here can be considered representative of NIST 610 as well.

  12. Report on scientist exchange program -analysis of uranium series nuclides in rocks and minerals-

    OpenAIRE

    1992-01-01

    This report mainly described the analysis of uranium series nuclidesin samples of rocks and minerials, giving detailed procedures about them. The related analytical methods and techniques included alpha spectrometry for U-238,U-234,Th-232 and Th-230, which employedanion exchange and TBP-tetrachloromethane extraction methods separating uranium and thorium from matrix and electrode position method preparing source disks, gamma spectrometry for Pb-210, Pb-214, Bi-214, Th-234 and Ra-226, oxine-ch...

  13. Uranium Isotope Fractionation during Adsorption, (Co)precipitation, and Biotic Reduction.

    Science.gov (United States)

    Dang, Duc Huy; Novotnik, Breda; Wang, Wei; Georg, R Bastian; Evans, R Douglas

    2016-12-06

    Uranium contamination of surface environments is a problem associated with both U-ore extraction/processing and situations in which groundwater comes into contact with geological formations high in uranium. Apart from the environmental concerns about U contamination, its accumulation and isotope composition have been used in marine sediments as a paleoproxy of the Earth's oxygenation history. Understanding U isotope geochemistry is then essential either to develop sustainable remediation procedures as well as for use in paleotracer applications. We report on parameters controlling U immobilization and U isotope fractionation by adsorption onto Mn/Fe oxides, precipitation with phosphate, and biotic reduction. The light U isotope ((235)U) is preferentially adsorbed on Mn/Fe oxides in an oxic system. When adsorbed onto Mn/Fe oxides, dissolved organic carbon and carbonate are the most efficient ligands limiting U binding resulting in slight differences in U isotope composition (δ(238)U = 0.22 ± 0.06‰) compared to the DOC/DIC-free configuration (δ(238)U = 0.39 ± 0.04‰). Uranium precipitation with phosphate does not induce isotope fractionation. In contrast, during U biotic reduction, the heavy U isotope ((238)U) is accumulated in reduced species (δ(238)U up to -1‰). The different trends of U isotope fractionation in oxic and anoxic environments makes its isotope composition a useful tracer for both environmental and paleogeochemical applications.

  14. Exploratory study of fission product yields of neutron-induced fission of 235U , 238U , and 239Pu at 8.9 MeV

    Science.gov (United States)

    Bhatia, C.; Fallin, B. F.; Gooden, M. E.; Howell, C. R.; Kelley, J. H.; Tornow, W.; Arnold, C. W.; Bond, E.; Bredeweg, T. A.; Fowler, M. M.; Moody, W.; Rundberg, R. S.; Rusev, G. Y.; Vieira, D. J.; Wilhelmy, J. B.; Becker, J. A.; Macri, R.; Ryan, C.; Sheets, S. A.; Stoyer, M. A.; Tonchev, A. P.

    2015-06-01

    Using dual-fission chambers each loaded with a thick (200 -400 -mg /c m2) actinide target of 235 ,238U or 239Pu and two thin (˜10 -100 -μ g /c m2) reference foils of the same actinide, the cumulative yields of fission products ranging from 92Sr to 147Nd have been measured at En= 8.9 MeV . The 2H(d ,n ) 3He reaction provided the quasimonoenergetic neutron beam. The experimental setup and methods used to determine the fission product yield (FPY) are described, and results for typically eight high-yield fission products are presented. Our FPYs for 235U(n ,f ) , 238U(n ,f ) , and 239Pu(n ,f ) at 8.9 MeV are compared with the existing data below 8 MeV from Glendenin et al. [Phys. Rev. C 24, 2600 (1981), 10.1103/PhysRevC.24.2600], Nagy et al. [Phys. Rev. C 17, 163 (1978), 10.1103/PhysRevC.17.163], Gindler et al. [Phys. Rev. C 27, 2058 (1983), 10.1103/PhysRevC.27.2058], and those of Mac Innes et al. [Nucl. Data Sheets 112, 3135 (2011), 10.1016/j.nds.2011.11.009] and Laurec et al. [Nucl. Data Sheets 111, 2965 (2010), 10.1016/j.nds.2010.11.004] at 14.5 and 14.7 MeV, respectively. This comparison indicates a negative slope for the energy dependence of most fission product yields obtained from 235U and 239Pu , whereas for 238U the slope issue remains unsettled.

  15. 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.

  16. Implications for soil environment from uranium isotopes of stalagmites

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    By analyzing U and Th isotopic compositions of 41 samples in two stalagmites from Hulu Cave, Nanjing, we first discovered that variations of 238U and d 234U0 along the stalagmite growth-sequence (covering a period from 75 to 18 kaBP) are in high similarity to summer insolation curve at 33°N and d 18O-based climate record of the studied stalagmites. The concentration of 238U is mainly controlled by content of organic matter in the soil above the cave. This mechanism can be used to explain our result that 238U curve of stalagmites is in phase with fluctuation of the d 18O record of the same stalagmites and summer insolation at cave locality. However, 238U concentration curve vs. age is, in amplitude, inconsistent with the climatic curves, possibly due to complex processes of soil-water-rock interaction. d 234U0 indicates pedogenic intensity of soil profile above the cave and sensitively reflects alternations of pedogenesis and aeolian accumulation processes of Xiashu loess in Nanjing. Consequently, uranium concentration and its isotope ratio in stalagmites may provide a new proxy for climate change.

  17. Accurate measurements of fission-fragment yields in 234,235,236,238U(γ,f with the SOFIA set-up

    Directory of Open Access Journals (Sweden)

    Chatillon A.

    2016-01-01

    Full Text Available SOFIA (Studies On Fission with Aladin is a new experimental set-up dedicated to accurate measurement of fission-fragments isotopic yields. It is located at GSI, the only place to use inverse kinematics at relativistic energies in order to study the (γ,f electromagnetic-induced fission. The SOFIA set-up is a large-acceptance magnetic spectrometer, which allows to fully identify both fission fragments in coincidence on the whole fission-fragment range. This paper will report on fission yields obtained in 234,235,236,238U(γ,f reactions.

  18. Comparison of the (p,xn) cross sections from /sup 238/U, /sup 235/U, and /sup 232/Th targets irradiated with 200-MeV protons

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Y.Y.; Zhou, M.L.

    1982-01-01

    We have measured absolute cross sections for (p,xn) reactions (x ranges from 0 to 8) from /sup 238/U, /sup 235/U, and /sup 232/Th targets irradiated with 200-MeV protons at the Brookhaven AGS Linac injector. Chemical yields were determined by using /sup 239/Np and /sup 233/Pa as tracers. Yield patterns obtained in this work can be compared to the experimental results and theoretical calculations from earlier work, and they are consistent within the framework of intranuclear cascade followed by neutron evaporation and fission competition.

  19. Evaluation of fission cross sections and covariances for {sup 233}U, {sup 235}U, {sup 238}U, {sup 239}Pu, {sup 240}Pu, and {sup 241}Pu

    Energy Technology Data Exchange (ETDEWEB)

    Kawano, Toshihiko [Kyushu Univ., Fukuoka (Japan); Matsunobu, Hiroyuki [Data Engineering, Inc. (Japan); Murata, Toru [AITEL Corporation, Tokyo (JP)] [and others

    2000-02-01

    A simultaneous evaluation code SOK (Simultaneous evaluation on KALMAN) has been developed, which is a least-squares fitting program to absolute and relative measurements. The SOK code was employed to evaluate the fission cross sections of {sup 233}U, {sup 235}U, {sup 238}U, {sup 239}Pu, {sup 240}Pu, and {sup 241}Pu for the evaluated nuclear data library JENDL-3.3. Procedures of the simultaneous evaluation and the experimental database of the fission cross sections are described. The fission cross sections obtained were compared with evaluated values given in JENDL-3.2 and ENDF/B-VI. (author)

  20. Investigations on the activity concentrations of 238U, 226RA, 228RA, 210PB and 40K in Jordan phosphogypsum and fertilizers.

    Science.gov (United States)

    Al-Jundi, J; Al-Ahmad, N; Shehadeh, H; Afaneh, F; Maghrabi, M; Gerstmann, U; Höllriegl, V; Oeh, U

    2008-01-01

    The activity concentrations of naturally occurring radionuclides ((238)U, (226)Ra, (228)Ra, (210)Pb and (40)K) in Jordanian phosphate ore, fertilizer material and phosphogypsum piles were investigated. The results show the partitioning of radionuclides in fertilizer products and phosphogypsum piles. The outcome of this study will enrich the Jordanian radiological map database, and will be useful for an estimation of the radiological impact of this industrial complex on the immediate environment. The activity concentration of (210)Pb was found to vary from 95 +/- 8 to 129 +/- 8 Bq kg(-1) with a mean value of 111 +/- 14 Bq kg(-1) in fertilizer samples, and from 364 +/- 8 to 428 +/- 10 Bq kg(-1) with a mean value of 391 +/- 30 Bq kg(-1) in phosphogypsum samples; while in phosphate wet rock samples, it was found to vary between 621 +/- 9 and 637 +/- 10 Bq kg(-1), with a mean value of 628 +/- 7 Bq kg(-1). The activity concentration of (226)Ra in fertilizer samples (between 31 +/- 4 and 42 +/- 5 Bq kg(-1) with a mean value of 37 +/- 6 Bq kg(-1)) was found to be much smaller than the activity concentration of (226)Ra in phosphogypsum samples (between 302 +/- 8 and 442 +/- 8 Bq kg(-1) with a mean value of 376 +/- 62 Bq kg(-1)). In contrast, the activity concentration of (238)U in fertilizer samples (between 1011 +/- 13 and 1061 +/- 14 Bq kg(-1) with a mean value of 1033 +/- 22 Bq kg(-1)) was found to be much higher than the activity concentration of (238)U in phosphogypsum samples (between 14 +/- 5 and 37 +/- 7 Bq kg(-1) with a mean value of 22 +/- 11 Bq kg(-1)). This indicates that (210)Pb and (226)Ra show similar behaviour, and are concentrated in phosphogypsum piles. In addition, both isotopes enhanced the activity concentration in phosphogypsum piles, while (238)U enhanced the activity concentration in the fertilizer. Due to the radioactivity released from the phosphate rock processing plants into the environment, the highest collective dose commitment for the lungs

  1. Potential impact of former Zn ore extraction activities on dissolved uranium distribution in the Riou-Mort watershed (France).

    Science.gov (United States)

    Saari, Hanna-Kaisa; Schmidt, Sabine; Coynel, Alexandra; Huguet, Stéphanie; Schäfer, Jörg; Blanc, Gérard

    2007-09-01

    The industrial basin of Decazeville (Riou-Mort watershed, South-West France) is well known for its heavy metal pollution and its subsequent environmental effects on the Lot-Garonne River system. The source of this pollution is the Riou-Mort River, which drains smelting waste areas. A first survey after remediation works has revealed elevated dissolved uranium (U(D)) concentrations in the outlet of the Riou-Mort River. The objective of this research is to identify the origin of U(D) in the Riou-Mort watershed and to evaluate the impact of industrial activities on this element. Uranium was measured at 10 water sampling sites, located upstream and downstream the industrial basin, and in three smelting waste deposits. Uranium concentrations in the smelting waste deposits reach up to 14.4 mg kg(-1) and (234U/238U) activity ratios (AR) are near unity. Dissolved U concentrations in the Riou-Mort River and its main tributaries ranges over two orders of magnitude from 0.02 to 6.1 microg L(-1). The highest levels were measured in a site with no anthropogenic pollution, upstream from the industrial area. This observation suggests that U(D) is mainly linked to weathering; the elevated U concentrations originate from the naturally occurring radioactive materials (NORM) located in the Permian bedrock and no significant U pollution exists, at present, in the Riou-Mort watershed. This work demonstrates that spatial monitoring coupled with a long time-series are an essential prerequisite in assessment of spatiotemporal variations of U(D), prior to a diagnostic of pollution in a small watershed.

  2. Polonium, uranium and plutonium radionuclides in aquatic and land ecosystem of Poland.

    Science.gov (United States)

    Skwarzec, Bogdan; Strumińska-Parulska, Dagmara I; Boryło, Alicja; Kabat, Krzysztof

    2012-01-01

    This article presents the results of study about distribution, inflow and accumulation of polonium, uranium and plutonium in aquatic and land environment of Poland and the southern Baltic Sea. Radionuclides of (210)Po, (234)U and (238)U as well as (239+240)Pu and (241)Pu are strongly accumulated in Baltic organisms and plants and transferred through the trophic chain. The values of bioconcentration factor (BCF) in Baltic plants and animals are higher for polonium and plutonium in comparison with uranium. The principal source of radionuclides in the southern Baltic Sea is their inflow with rivers. Total annual runoff of polonium, uranium and plutonium from the Vistula and the Odra as well as the Pomeranian rivers were calculated at 95 GBq of (210)Po, 750 GBq of (234+238)U and 160 MBq of (238+239+240)Pu. Seasonal and spatial variability of (210)Po, (238)U and (239+240)Pu levels in the Vistula and the Odra drainage basins were assessed by application of neural-network based classification, especially cluster analysis (CA), principal component analysis (PCA) and self-organizing maps (SOM). The result for the Vistula river indicated correlation between polonium and plutonium as well as polonium and uranium. In the Odra drainage basin, the biggest differences were observed in the case of (238)U. To assess if there are statistically significant differences in mean concentration values of (210)Po, (238)U and (239+240)Pu for the Vistula and the Odra rivers drainage basins were obtained by used of the non-parametric tests. Comparing to the Vistula catchment area, statistically differences concentration of (210)Po and (239+240)Pu in all year was observed for river samples collected on the Odra drainage basin.

  3. Iowa Bedrock Topography

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — The Map of the Elevation of the Bedrock Surface in Iowa was compiled using all available data, principally information from GEOSAM, supplemented with well and boring...

  4. Iowa Bedrock Surface Elevation

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — This Digital Elevation Model (DEM) of the bedrock surface elevation in Iowa was compiled using all available data, principally information from GEOSAM, supplemented...

  5. Ogallala Bedrock Data Enhancement

    Data.gov (United States)

    Kansas Data Access and Support Center — This data set provides an enhanced estimate of the bedrock elevation of the Ogallala Aquifer in Kansas based on lithologic logs from a variety of sources. The data...

  6. Origin of the {sup 238}U-{sup 230}Th disequilibrium in magmas from subduction zones: the Arenal example; Origine du desequilibre {sup 238}U-{sup 230}TH dans les magmas des zones de subduction: exemple de l`Arenal

    Energy Technology Data Exchange (ETDEWEB)

    Villemant, B. [Paris-6 Univ., 75 (France)

    1996-12-31

    The existence in some volcanic products of strong excess of {sup 238}U with respect to {sup 230}Th is one of the characteristics of volcanic arc magmas. These excesses are generally attributed to fluid additions inside mantellic sources before magma segregation, differentiation and eruption. These fluids should be linked to the dehydration of the subducted rocks. These hypotheses are essentially based on correlations between {sup 10}Be, {sup 87}Sr anomalies, Ba/La ratios and on the distribution of volcanic centers with respect to the subduction zone. Recent studies suggest an evolution of the composition of volcanic sources in Central America from a depleted mantle type (MORB) in the North (Nicaragua) to a less transformed enriched type (OIB) in the South (Costa Rica). The Arenal volcano belongs to a transition zone between these two types. The preliminary study of trace elements and {sup 238}U-{sup 230}Th disequilibria in recent volcanic products (1968-1993) indicates a more complex situation. At least two different mantle sources were successively involved characterized by different Th/La and La/Yb ratios and very different to the OIB type. Also most lavas are in equilibrium with {sup 238}U/{sup 232}Th ratios of about 1.2 to 1.3. However, in eruptive cycle, some lavas are characterized by a strong {sup 238}U excess with respect to {sup 230}Th with cannot be linked to the sources, even when modified by fluids in depth. These results are interpreted in terms of heterogeneities of mantle sources and low depths late interactions with hydrothermal fluids during eruptions. Abstract only. (J.S.). 2 refs.

  7. Determination of (238)U, (232)Th and (40)K activity concentrations in riverbank soil along the Chao Phraya river basin in Thailand.

    Science.gov (United States)

    Santawamaitre, T; Malain, D; Al-Sulaiti, H A; Bradley, D A; Matthews, M C; Regan, P H

    2014-12-01

    The activity concentrations of (238)U, (232)Th and (40)K in riverbank soil along the Chao Phraya river basin was determined through gamma-ray spectrometry measurements made using a hyper-pure germanium detector in a low background configuration. The ranges of activity concentrations of (238)U, (232)Th and (40)K were found to be 13.9 ↔ 76.8, 12.9 ↔ 142.9 and 178.4 ↔ 810.7 Bq kg(-1), respectively. The anthropogenic radionuclide, (137)Cs, was not observed in statistically significant amounts above the background level in the current study. The absorbed gamma dose rate in air at 1 m above the ground surface, the outdoor annual effective dose equivalent, the values of the radium equivalent activity and the external hazard index associated with all the soil samples in the present work were evaluated. The results indicate that the radiation hazard from primordial radionuclides in all soil samples from the area studied in this current work is not significant.

  8. Seasonal variations of total {sup 234}Th and dissolved {sup 238}U concentration activities in surface water of Bransfield Strait, Antarctica, from March to October 2011

    Energy Technology Data Exchange (ETDEWEB)

    Lapa, Flavia V.; Oliveira, Joselene de; Costa, Alice M.R., E-mail: fvlapa@ipen.br, E-mail: jolivei@ipen.br, E-mail: lice_mrc@hotmail.com [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Sao Paulo, SP (Brazil). Laboratorio de Radiometria Ambiental; Braga, Elisabete S., E-mail: edsbraga@usp.br [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Inst. Oceanografico. Lab. de Nutrientes, Micronutrientes e Tracos nos Oceanos

    2013-07-01

    In this study the naturally occurring radionuclides {sup 234}Th and {sup 238}U were used to investigate the magnitude of upper ocean particulate organic carbon export in Bransfield Strait, Southern Ocean. This region is the largest oceanic high-nitrate low-chlorophyll (HNLC) area in the world and is known to contribute to regulate of the atmospheric CO{sub 2} via the biological pump. Due to its different geochemical behavior in seawater, the resulting U/Th disequilibria can be easily used to constrain the transport rates of particles and reaction processes between solution and particulate phases. Sampling occurred during the summer (March and November) 2011. Total {sup 234}Th activities in surface seawater samples ranged from 1.3 to 3.7 dpm L{sup -1} (station EB 011) during March/11 campaign, while in October/11 total {sup 234}Th activity concentrations varied from 1.4 to 2.9 dpm L{sup -1}. Highest total {sup 234}Th activities were found late in the austral summer season. Activity concentrations of dissolved {sup 238}U in surface seawater varied from 2.1 to 2.4 dpm L{sup -1}. Taking into account all sampling stations established in March and October/11 the relative variability of total {sup 234}Th distribution was 22%. (author)

  9. Flow in bedrock canyons.

    Science.gov (United States)

    Venditti, Jeremy G; Rennie, Colin D; Bomhof, James; Bradley, Ryan W; Little, Malcolm; Church, Michael

    2014-09-25

    Bedrock erosion in rivers sets the pace of landscape evolution, influences the evolution of orogens and determines the size, shape and relief of mountains. A variety of models link fluid flow and sediment transport processes to bedrock incision in canyons. The model components that represent sediment transport processes are increasingly well developed. In contrast, the model components being used to represent fluid flow are largely untested because there are no observations of the flow structure in bedrock canyons. Here we present a 524-kilometre, continuous centreline, acoustic Doppler current profiler survey of the Fraser Canyon in western Canada, which includes 42 individual bedrock canyons. Our observations of three-dimensional flow structure reveal that, as water enters the canyons, a high-velocity core follows the bed surface, causing a velocity inversion (high velocities near the bed and low velocities at the surface). The plunging water then upwells along the canyon walls, resulting in counter-rotating, along-stream coherent flow structures that diverge near the bed. The resulting flow structure promotes deep scour in the bedrock channel floor and undercutting of the canyon walls. This provides a mechanism for channel widening and ensures that the base of the walls is swept clear of the debris that is often deposited there, keeping the walls nearly vertical. These observations reveal that the flow structure in bedrock canyons is more complex than assumed in the models presently used. Fluid flow models that capture the essence of the three-dimensional flow field, using simple phenomenological rules that are computationally tractable, are required to capture the dynamic coupling between flow, bedrock erosion and solid-Earth dynamics.

  10. A new series of uranium isotope reference materials for investigating the linearity of secondary electron multipliers in isotope mass spectrometry

    Science.gov (United States)

    Richter, S.; Alonso, A.; Aregbe, Y.; Eykens, R.; Kehoe, F.; Kühn, He; Kivel, N.; Verbruggen, A.; Wellum, R.; Taylor, P. D. P.

    2009-04-01

    A new series of gravimetrically prepared uranium isotope reference materials, the so-called IRMM-074 series, with the n(235U)/n(238U) isotope ratio held constant at unity and the n(233U)/n(238U) isotope ratios varying from 1.0 to 10-6 has been prepared and certified. This series is suited for calibration of secondary electron multipliers used widely in isotope mass spectrometry, in particular for techniques such as thermal ionization mass spectrometry (TIMS), inductively coupled plasma mass spectrometry (ICPMS), accelerator mass spectrometry (AMS) and resonance ionization mass spectrometry (RIMS). The new IRMM-074 was prepared as a replacement for the already exhausted IRMM-072 predecessor series. Uranium materials with high isotopic enrichments of 233U, 235U and 238U were purified using identical methods involving separation on anion and cation column followed by a precipitation as peroxide. The oxides were calcined to convert them to U3O8 simultaneously, in an oven installed in a glove-box that provided a controlled low-humidity environment. The oxides of 235U and 238U were weighed and mixed with a mole ratio n(235U)/n(238U) = 1.0 and then dissolved. The 233U oxide was dissolved to form a separate solution with the same concentration and 6rom this primary solution three dilutions were made by weighing. A weighed amount of the n(235U)/n(238U) solution and weighed amounts of the 233U solutions were mixed in various proportions in order to achieve n(233U)/n(238U) isotope ratios varying from 1.0 to 10-6. The methods for the preparation, the mixing and the mixing calculations are described. The expanded uncertainties (coverage factor k = 2) of the certified isotope ratios for the IRMM-074 series are 0.015% for the n(235U)/n(238U) ratio and 0.025% for the n(233U)/n(238U) ratios, which constitutes an improvement compared to those of the predecessor IRMM-072 series. In addition, recent observations regarding the linearity response of secondary electron multipliers (SEMs

  11. Overview of Uranium Isotopic Reference Materials at IRMM

    Science.gov (United States)

    Alonso-Munoz, A.; Richter, S.; Eykens, R.; Aregbe, Y.; Kuehn, H.; Verbruggen, A.

    2007-12-01

    For many applications in the geological sciences, in particular in geochemistry research, isotope ratio measurements play a significant role. For instance, in geochronology isotope abundances of uranium and its daughter products thorium and lead have been used since more than five decades to determine the age of various samples of geological interest. However, in order to validate mass spectrometric measurement procedures and to calibrate detector systems, suitable isotope reference materials are needed. IRMM is a well recognized provider for nuclear isotope reference materials to the nuclear industry and nuclear safeguards authorities, which can also be used for geological applications. This paper gives an overview of isotope reference materials for uranium prepared and certified at IRMM. These materials are synthetic isotope reference materials prepared based on proven methods of purifying and mixing highly enriched oxides. Firstly, a set of 10 mixtures of 233U, 235U and 238U was made in which the 235U/238U ratios were kept at 1:1 and the 233U/235U ratios varied from 1.0 to 10-6 (IRMM-072). This set is ideal for checking the linearity response of detectors used in isotope mass spectrometry. Recently, after the IRMM-072 series was exhausted, it has been replaced by the IRMM-073 and IRMM-074 series. Secondly the double spike IRMM-3636 with a 233U/236U ratio of 1:1 was prepared which allows internal mass fractionation correction for high precision 235U/238U ratio measurements. The 234U abundance of this double spike material is low enough to allow an accurate and precise correction of 234U/238U ratios, even for measurements of close to equilibrium uranium samples.

  12. SOME ASPECTS OF THE INFLUENCE OF URANIUM EXPLOITATION ON THE ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    Stefan DIMOVSKI

    2012-11-01

    Full Text Available Gamma-ray spectrometric measurements of samples of riverbed sediments and soil samples taken along the valley of a river, which runs very close to a uranium mine retaining dam are performed. The content of 238U, 226Ra, 210 Pb, 232Th, and 40K is analyzed. Up to a distance of about 6 km away from the retaining dam, 238U, 226Ra and 210Pb have high concentrations and the content in the sediments samples is consistently higher than the content in the soil samples. In the same interval are observed considerable fluctuations in the contents related to the swamping of the river. Receding at a greater distance from the retaining dam, the concentration of 238U, 226Ra and 210Pb decreases and has values close to the average ones. A very close correlation is established between the contents of the three radioactive nuclides. Regarding 232Th and 40K, the distribution characteristics along the profile are different in comparison with those of the 238U family members. The performed research contributes to the estimate of the radioactive contamination in a specific area situated in the vicinity of a uranium deposit exploited through underground mining.

  13. Bedrock geologic map of Vermont

    Science.gov (United States)

    Ratcliffe, Nicholas M.; Stanley, Rolfe S.; Gale, Marjorie H.; Thompson, Peter J.; Walsh, Gregory J.; With contributions by Hatch, Norman L.; Rankin, Douglas W.; Doolan, Barry L.; Kim, Jonathan; Mehrtens, Charlotte J.; Aleinikoff, John N.; McHone, J. Gregory; Cartography by Masonic, Linda M.

    2011-01-01

    The Bedrock Geologic Map of Vermont is the result of a cooperative agreement between the U.S. Geological Survey (USGS) and the State of Vermont. The State's complex geology spans 1.4 billion years of Earth's history. The new map comes 50 years after the most recent map of the State by Charles G. Doll and others in 1961 and a full 150 years since the publication of the first geologic map of Vermont by Edward Hitchcock and others in 1861. At a scale of 1:100,000, the map shows an uncommon level of detail for State geologic maps. Mapped rock units are primarily based on lithology, or rock type, to facilitate derivative studies in multiple disciplines. The 1961 map was compiled from 1:62,500-scale or smaller maps. The current map was created to integrate more detailed (1:12,000- to 1:24,000-scale) modern and older (1:62,500-scale) mapping with the theory of plate tectonics to provide a framework for geologic, tectonic, economic, hydrogeologic, and environmental characterization of the bedrock of Vermont. The printed map consists of three oversize sheets (52 x 76 inches). Sheets 1 and 2 show the southern and northern halves of Vermont, respectively, and can be trimmed and joined so that the entire State can be displayed as a single entity. These sheets also include 10 cross sections and a geologic structure map. Sheet 3 on the front consists of descriptions of 486 map units, a correlation of map units, and references cited. Sheet 3 on the back features a list of the 195 sources of geologic map data keyed to an index map of 7.5-minute quadrangles in Vermont, as well as a table identifying ages of rocks dated by uranium-lead zircon geochronology.

  14. Fission Product Yields of 233U, 235U, 238U and 239Pu in Fields of Thermal Neutrons, Fission Neutrons and 14.7-MeV Neutrons

    Science.gov (United States)

    Laurec, J.; Adam, A.; de Bruyne, T.; Bauge, E.; Granier, T.; Aupiais, J.; Bersillon, O.; Le Petit, G.; Authier, N.; Casoli, P.

    2010-12-01

    The yields of more than fifteen fission products have been carefully measured using radiochemical techniques, for 235U(n,f), 239Pu(n,f) in a thermal spectrum, for 233U(n,f), 235U(n,f), and 239Pu(n,f) reactions in a fission neutron spectrum, and for 233U(n,f), 235U(n,f), 238U(n,f), and 239Pu(n,f) for 14.7 MeV monoenergetic neutrons. Irradiations were performed at the EL3 reactor, at the Caliban and Prospero critical assemblies, and at the Lancelot electrostatic accelerator in CEA-Valduc. Fissions were counted in thin deposits using fission ionization chambers. The number of fission products of each species were measured by gamma spectrometry of co-located thick deposits.

  15. Experimental Neutron-Induced Fission Fragment Mass Yields of 232Th and 238U at Energies from 10 to 33 MeV

    CERN Document Server

    Simutkin, V D; Blomgren, J; Österlund, M; Bevilacqua, R; Ryzhov, I V; Tutin, G A; Yavshits, S G; Vaishnene, L A; Onegin, M S; Meulders, J P; Prieels, R

    2013-01-01

    Development of nuclear energy applications requires data for neutron-induced reactions for actinides in a wide neutron energy range. Here we describe measurements of pre-neutron emission fission fragment mass yields of 232Th and 238U at incident neutron energies from 10 to 33 MeV. The measurements were done at the quasi-monoenergetic neutron beam of the Louvain-la-Neuve cyclotron facility CYCLONE; a multi-section twin Frisch-gridded ionization chamber was used to detect fission fragments. For the peak neutron energies at 33, 45 and 60 MeV, the details of the data analysis and the experimental results have been published before and in this work we present data analysis in the low-energy tail of the neutron energy spectra. The preliminary measurement results are compared with available experimental data and theoretical predictions.

  16. Identification of 45 New Neutron-Rich Isotopes Produced by In-Flight Fission of a 238U Beam at 345 MeV/nucleon

    OpenAIRE

    Ohnishi, Tetsuya; Kubo*, Toshiyuki; Kusaka, Kensuke; Yoshida, Atsushi; Yoshida, Koichi; Ohtake, Masao; Fukuda, Naoki; Takeda, Hiroyuki; Kameda, Daisuke; Tanaka, Kanenobu; Inabe, Naohito; Yanagisawa, Yoshiyuki; Gono, Yasuyuki; Watanabe, Hiroshi; Otsu, Hideaki

    2010-01-01

    A search for new isotopes using in-flight fission of a 345 MeV/nucleon 238U beam has been carried out at the RI Beam Factory at the RIKEN Nishina Center. Fission fragments were analyzed and identified by using the superconducting in-flight separator BigRIPS. We observed 45 new neutron-rich isotopes: 71Mn, 73,74Fe, 76Co, 79Ni, 81,82Cu, 84,85Zn, 87Ga, 90Ge, 95Se, 98Br, 101Kr, 103Rb, 106,107Sr, 108,109Y, 111,112Zr, 114,115Nb, 115,116,117Mo, 119,120Tc, 121,122,123,124Ru, 123,124,125,126Rh, 127,12...

  17. Identification of 45 New Neutron-Rich Isotopes Produced by In-Flight Fission of a 238U Beam at 345 MeV/nucleon

    CERN Document Server

    Ohnishi, Tetsuya; Kusaka, Kensuke; Yoshida, Atsushi; Yoshida, Koichi; Ohtake, Masao; Fukuda, Naoki; Takeda, Hiroyuki; Kameda, Daisuke; Tanaka, Kanenobu; Inabe, Naohito; Yanagisawa, Yoshiyuki; Gono, Yasuyuki; Watanabe, Hiroshi; Otsu, Hideaki; Baba, Hidetada; Ichihara, Takashi; Yamaguchi, Yoshitaka; Takechi, Maya; Nishimura, Shunji; Ueno, Hideki; Yoshimi, Akihiro; Sakurai, Hiroyoshi; Motobayashi, Tohru; Nakao, Taro; Mizoi, Yutaka; Matsushita, Masafumi; Ieki, Kazuo; Kobayashi, Nobuyuki; Tanaka, Kana; Kawada, Yosuke; Tanaka, Naoki; Deguchi, Shigeki; Satou, Yoshiteru; Kondo, Yosuke; Nakamura, Takashi; Yoshinaga, Kenta; Ishii, Chihiro; Yoshii, Hideakira; Miyashita, Yuki; Uematsu, Nobuya; Shiraki, Yasutsugu; Sumikama, Toshiyuki; Chiba, Junsei; Ideguchi, Eiji; Saito, Akito; Yamaguchi, Takayuki; Hachiuma, Isao; Suzuki, Takeshi; Moriguchi, Tetsuaki; Ozawa, Akira; Ohtsubo, Takashi; Famiano, Michael A; Geissel, Hans; Nettleton, Anthony S; Tarasov, Oleg B; Bazin, Daniel P; Sherrill, Bradley M; Manikonda, Shashikant L; Nolen, Jerry A

    2010-01-01

    A search for new isotopes using in-flight fission of a 345 MeV/nucleon 238U beam has been carried out at the RI Beam Factory at the RIKEN Nishina Center. Fission fragments were analyzed and identified by using the superconducting in-flight separator BigRIPS. We observed 45 new neutron-rich isotopes: 71Mn, 73,74Fe, 76Co, 79Ni, 81,82Cu, 84,85Zn, 87Ga, 90Ge, 95Se, 98Br, 101Kr, 103Rb, 106,107Sr, 108,109Y, 111,112Zr, 114,115Nb, 115,116,117Mo, 119,120Tc, 121,122,123,124Ru, 123,124,125,126Rh, 127,128Pd, 133Cd, 138Sn, 140Sb, 143Te, 145I, 148Xe, and 152Ba.

  18. High accuracy determination of the $^{238}$U/$^{235}$U fission cross section ratio up to $\\sim$1 GeV at n_TOF (CERN)

    CERN Document Server

    Paradela, C; Tarrío, D; Leal-Cidoncha, E; Leong, L S; Tassan-Got, L; Naour, C Le; Duran, I; Colonna, N; Audouin, L; Mastromarco, M; Meo, S Lo; Ventura, A; Altstadt, S; Andrzejewski, J; Barbagallo, M; Bécares, V; Bečvář, F; Belloni, F; Berthoumieux, E; Billowes, J; Boccone, V; Bosnar, D; Brugger, M; Calviño, F; Cano-Ott, D; Carrapiço, C; Cerutti, F; Chiaveri, E; Chin, M; Cortés, G; Cortés-Giraldo, M A; Cosentino, L; Diakaki, M; Domingo-Pardo, C; Dressler, R; Eleftheriadis, C; Ferrari, A; Finocchiaro, P; Fraval, K; Ganesan, S; García, A R; Giubrone, G; Gómez-Hornillos, M B; Gonçalves, I F; González-Romero, E; Griesmayer, E; Guerrero, C; Gunsing, F; Gurusamy, P; Heinitz, S; Jenkins, D G; Jericha, E; Käppeler, F; Karadimos, D; Kivel, N; Kokkoris, M; Krtička, M; Kroll, J; Langer, C; Lederer, C; Leeb, H; Losito, R; Manousos, A; Marganiec, J; Martínez, T; Massimi, C; Mastinu, P; Mendoza, E; Mengoni, A; Milazzo, P M; Mingrone, F; Mirea, M; Mondalaers, W; Musumarra, A; Pavlik, A; Perkowski, J; Plompen, A; Praena, J; Quesada, J; Rauscher, T; Reifarth, R; Riego, A; Roman, F; Rubbia, C; Sarmento, R; Saxena, A; Schillebeeckx, P; Schmidt, S; Schumann, D; Tagliente, G; Tain, J L; Tsinganis, A; Valenta, S; Vannini, G; Variale, V; Vaz, P; Versaci, R; Vermeulen, M J; Vlachoudis, V; Vlastou, R; Wallner, A; Ware, T; Weigand, M; Weiß, C; Wright, T; Žugec, P

    2015-01-01

    The $^{238}$U to $^{235}$U fission cross section ratio has been determined at n_TOF up to $\\sim$1 GeV, with two different detection systems, in different geometrical configurations. A total of four datasets have been collected and compared. They are all consistent to each other within the relative systematic uncertainty of 3-4%. The data collected at n_TOF have been suitably combined to yield a unique fission cross section ratio as a function of the neutron energy. The result confirms current evaluations up to 200 MeV. A good agreement is also observed with theoretical calculations based on the INCL++/Gemini++ combination up to the highest measured energy. The n_TOF results may help solving a long-standing discrepancy between the two most important experimental dataset available so far above 20 MeV, while extending the neutron energy range for the first time up to $\\sim$1 GeV.

  19. (238)U/(235)U isotope ratios of crustal material, rivers and products of hydrothermal alteration: new insights on the oceanic U isotope mass balance.

    Science.gov (United States)

    Noordmann, Janine; Weyer, Stefan; Georg, R Bastian; Jöns, Svenja; Sharma, Mukul

    2016-01-01

    In this study, the U isotope composition, n((238)U)/n((235)U), of major components of the upper continental crust, including granitic rocks of different age and post-Archaean shales, as well as that of rivers (the major U source to the oceans) was investigated. Furthermore, U isotope fractionation during the removal of U at mid-ocean ridges, an important sink for U from the oceans, was investigated by the analyses of hydrothermal water samples (including low- and high-temperature fluids), low-temperature altered basalts and calcium carbonate veins. All analysed rock samples from the continental crust fall into a limited range of δ(238)U between -0.45 and -0.21 ‰ (relative to NBL CRM 112-A), with an average of -0.30 ± 0.15 ‰ (2 SD, N = 11). Despite differences in catchment lithologies, all major rivers define a relatively narrow range between -0.31 and -0.13 ‰, with a weighted mean isotope composition of -0.27 ‰, which is indistinguishable from the estimate for the upper continental crust (-0.30 ‰). Only some tributary rivers from the Swiss Alps display a slightly larger range in δ(238)U (-0.29 to +0.01 ‰) and lower U concentrations (0.87-3.08 nmol/kg) compared to the investigated major rivers (5.19-11.69 nmol/kg). These findings indicate that only minor net U isotope fractionation occurs during weathering and transport of material from the continental crust to the oceans. Altered basalts display moderately enriched U concentrations (by a factor of 3-18) compared to those typically observed for normal mid-ocean ridge basalts. These, and carbonate veins within altered basalts, show large U isotope fractionation towards both heavy and light U isotope compositions (ranging from -0.63 to +0.27 ‰). Hydrothermal water samples display low U concentrations (0.3-1 nmol/kg) and only limited variations in their U isotope composition (-0.43 ± 0.25 ‰) around the seawater value. Nevertheless, two of the investigated fluids display

  20. The cumulative effect of three decades of phosphogypsum amendments in reclaimed marsh soils from SW Spain: (226)Ra, (238)U and Cd contents in soils and tomato fruit.

    Science.gov (United States)

    Abril, José-María; García-Tenorio, Rafael; Enamorado, Santiago M; Hurtado, M Dolores; Andreu, Luis; Delgado, Antonio

    2008-09-15

    Phosphogypsum (PG), a by-product of the phosphate fertiliser industries, has been applied as soil amendment to reduce Na saturation in soils, as in the reclaimed marsh area from SW Spain, where available PG has a typical fingerprint of 710+/-40 Bq kg(-1) of (226)Ra, 165+/-15 Bq kg(-1) of (238)U and 2.8+/-0.4 mg kg(-1) of Cd. This work was focussed on the cumulative effects of PG amendments on the enrichment of these pollutants in cultivated soils and plants (Lycopersicum esculentum Mill L.) from the area studied, where PG has been applied since 1978 at recommended rates of 20-25 Mg ha(-1) every 2-3 years. A field experiment was conducted over three years to compare activity concentrations of (226)Ra ((214)Pb) and (238)U ((234)Th) in non-reclaimed soils, reclaimed soils with no additional PG application, and reclaimed soils with two additional PG applications. A non-significant effect of two PG amendments (in three years) was observed when compared with non-amended reclaimed plots. Nevertheless, a significant (p<0.05) enrichment of (226)Ra was observed in the surface horizon (0-30 cm) of reclaimed plots relative to deeper horizons and also when compared with the surface horizon of non-reclaimed soil (p<0.05), thereby revealing the cumulative effect of three decades of PG applications. Furthermore, the effect of a continuous application of PG was studied by analysing soils and tomato fruits from six commercial farms with different cumulative rates of PG applied. Cadmium concentrations in tomatoes, which were one order of magnitude higher than those found in tomatoes from other areas in South Spain, were positively correlated (r = 0.917) with (226)Ra-concentration in soils, which can be considered an accurate index of the cumulative PG rate of each farm.

  1. Uranium and radium in water samples around the Nikola Tesla B lignite-fired power plant - Obrenovac, Serbia

    Directory of Open Access Journals (Sweden)

    Žunić Zora S.

    2011-01-01

    Full Text Available This paper deals with the analysis of natural radionuclide content in 23 water samples collected in the vicinity of the Nikola Tesla B thermal power plant, Serbia. All samples were analyzed for 226Ra and uranium isotopes (238U, 234U activity using radiochemical methods and alpha spectrometry. Obtained results show that the activity concentrations for uranium and radium in the water around the thermal power plant are low when compared to those from areas across Serbia with their enhanced natural uranium and radium content. No important radiological hazard related to uranium and radium activity stored in heap was found.

  2. Plutonium, (137)Cs and uranium isotopes in Mongolian surface soils.

    Science.gov (United States)

    Hirose, K; Kikawada, Y; Igarashi, Y; Fujiwara, H; Jugder, D; Matsumoto, Y; Oi, T; Nomura, M

    2017-01-01

    Plutonium ((238)Pu and (239,240)Pu), (137)Cs and plutonium activity ratios ((238)Pu/(239,240)Pu) as did uranium isotope ratio ((235)U/(238)U) were measured in surface soil samples collected in southeast Mongolia. The (239,240)Pu and (137)Cs concentrations in Mongolian surface soils (surface soils (0.013-0.06) coincided with that of global fallout. The (235)U/(238)U atom ratios in the surface soil show the natural one. There was a good correlation between the (239,240)Pu and (137)Cs concentrations in the surface soils. We introduce the migration depth to have better understanding of migration behaviors of anthropogenic radionuclides in surface soil. We found a difference of the migration behavior between (239,240)Pu and (137)Cs from (137)Cs/(239,240)Pu - (137)Cs plots for the Mongolian and Tsukuba surface soils; plutonium in surface soil is migrated easier than (137)Cs.

  3. The influence of the nature of soil and plant and pollution on the 238U, 232Th, 222Rn and 220Rn concentrations in various natural honey samples using nuclear track detectors: Impact on the adult consumers

    Indian Academy of Sciences (India)

    M A Misdaq; A Mortassim

    2009-11-01

    238U and 232Th concentrations as well as 222Rn and 220Rn -activities per unit volume were measured in various natural honey samples collected from different regions in Morocco using CR-39 and LR-115 type II solid state nuclear track detectors (SSNTDs). These radionuclides were also measured in soils, plant flowers and nectar solutions corresponding to the honey samples studied. In addition, these radionuclides were measured in different imported honey samples. The measured 238U, 232Th, 222Rn and 220Rn concentrations ranged from (1.5 ± 0.1) mBq kg-1 to (10.6 ± 0.6) mBq kg-1, (1.1 ± 0.1) mBq kg-1 to (4.2 ± 0.2) mBq kg-1 , (1.5 ± 0.1) Bq kg-1 to (10.6 ± 0.6) Bq kg-1 and (1.1 ± 0.1) Bq kg-1 to (4.2 ± 0.2) Bq kg-1 for the honey samples studied, respectively. Annual 238U, 232Th and 222Rn intakes by Moroccan adults from the consumption of honey were assessed. The influence of the nature of soil and plant on the 238U and 232Th contents of the studied honey samples was investigated. These measurements were completed by an investigation of the 238U and 232 Th transfer between soils and plant flowers and that between plant flowers and honey, and also by the investigation of the influence of pollution due to different material dusts on 238U, 232Th and 222Rn in the honey samples studied. Committed equivalent doses due to the annual intake of 238U, 232Th and 222Rn were evaluated in the organs of adult members of the Moroccan rural population from the ingestion of the honey samples. The maximum total committed effective dose due to 238U, 232Th and 222Rn from the ingestion of natural honey by the Moroccan rural population was found to be equal to 0.64 Sv y-1 .

  4. CREATING THE KULTUK POLYGON FOR EARTHQUAKE PREDICTION: VARIATIONS OF (234U/238U) AND 87SR/86SR IN GROUNDWATER FROM ACTIVE FAULTS AT THE WESTERN SHORE OF LAKE BAIKAL

    OpenAIRE

    S. V. Rasskazov; E. P. Chebykin; A. M. Ilyasova; E. N. Vodneva; I. S. Chuvashova; Bornyakov, S. A.; A. K. Seminsky; S. V. Snopkov; V. V. Chechel'nitsky; N. A. Gileva

    2015-01-01

    Introduction. Determinations of (234U/238U) in groundwater samples are used for monitoring current deformations in active faults (parentheses denote activity ratio units). The cyclic equilibrium of activity ratio 234U/238U≈≈(234U/238U)≈γ≈1 corresponds to the atomic ratio ≈5.47×10–5. This parameter may vary due to higher contents of 234U nuclide in groundwater as a result of rock deformation. This effect discovered by P.I. Chalov and V.V. Cherdyntsev was described in [Cherdyntsev, 1969, 1973; ...

  5. Uranium isotopic data in uraninite spent fuel from the Bangombe natural nuclear reactor (Gabon) and its surroundings

    Science.gov (United States)

    Fernandez-Diaz; Quejido; Crespo; Perez del Villar L; Martin-Sanchez; Lozano

    2000-07-01

    In the framework of the "Oklo-Natural Analogue Phase II" Project, uraninite from the Bangombe natural reactor and samples from its host rock were analyzed to determine their uranium isotopic composition by thermal ionisation mass spectrometry, inductively coupled plasma mass spectrometry and alpha spectrometry. There were several objectives for this work: (i) to validate the 235U/238U isotopic ratios obtained by these techniques; (ii) to test the use of the 235U/238U ratio of uraninite as a tracer of migration/retention processes of uranium from the source term to the far field; (iii) to evaluate the most recent migration/retention processes of uranium in the system by U-series disequilibrium.

  6. Uranium isotopic data in uraninite spent fuel from the Bangombe natural nuclear reactor (Gabon) and its surroundings

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Diaz, M.; Quejido, A.J.; Crespo, M.T.; Villar, L.P. del; Martin-Sanchez, A. E-mail: ams@unex.es; Lozano, J.C

    2000-07-15

    In the framework of the 'Oklo-Natural Analogue Phase II' Project, uraninite from the Bangombe natural reactor and samples from its host rock were analyzed to determine their uranium isotopic composition by thermal ionisation mass spectrometry, inductively coupled plasma mass spectrometry and alpha spectrometry. There were several objectives for this work: (i) to validate the {sup 235}U/{sup 238}U isotopic ratios obtained by these techniques; (ii) to test the use of the {sup 235}U/{sup 238}U ratio of uraninite as a tracer of migration/retention processes of uranium from the source term to the far field; (iii) to evaluate the most recent migration/retention processes of uranium in the system by U-series disequilibrium.

  7. Use of LabSOCS for determination of specific concentrations of {sup 40}K, {sup 238}U and {sup 232}Th in fertilizer samples; Uso de LabSOCS no calculo da eficiencia de detecao para determinacao da concentracao especifica de {sup 40}K, {sup 238}U e {sup 232}Th em amostras de fertilizantes

    Energy Technology Data Exchange (ETDEWEB)

    Garcez, Ricardo Washington Dutra; Lopes, Jose Marques; Silva, Ademir Xavier da, E-mail: rgarcez@con.ufrj.br, E-mail: marqueslopez@yahoo.com.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear; Domingues, Alessandro Mariano; Lima, Marco Frota, E-mail: slessandrodomingues@fisica.if.uff.br, E-mail: marcofrotalima@yahoo.com.br [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Instituto de Biologia

    2015-07-01

    Use of fertilizer is an established practice worldwide to promote agricultural productivity increased without increasing the planted area, resulting in native forests protection and increase of the food availability. Some kinds of fertilizer have in their chemical composition some radionuclides due the origin of its feedstock, such as {sup 238}U, the {sup 232}Th, and their descendants, beyond {sup 40}K. Knowledge of the radioactivity levels in the environment is great importance to know the gamma radiation dose that the human being is exposed. For identification and quantitation of radionuclides, it was used gamma spectrometry where HPGe detector was used to obtain the spectra, and LabSOCS software for calculating the detection efficiency for each energy. The values of {sup 232}Th specific concentrations ranged from 4.1 to 368.1 Bq.Kg{sup -1} , the values of {sup 238}U specific concentrations ranged from 16.0 to 647.7 Bq.Kg{sup -1} and {sup 40}K specific concentrations ranged from 19.1 to 12713 Bq.Kg{sup -1} . Concentrations of values are consistent with those found in literature. (author)

  8. Transfer Rates of 238U and 232Th for E. globulus, A. mearnsii, H. filipendula and Hazardous Effects of the Usage of Medicinal Plants From Around Gold Mine Dump Environs

    Directory of Open Access Journals (Sweden)

    Victor M. Tshivhase

    2015-12-01

    Full Text Available Medicinal plant consumption can be a source of human exposure to radioactive elements such as 238U and 232Th, which can lead to internal radiation doses. The uptake of 238U and 232Th from soils to the leaf samples of three different medicinal plant species (Eucalyptus globulus, Acacia mearnsii and Hyparrhenia filipendula from the purlieu of the Princess gold mine dump, an abandoned contaminated tailings storage site (TSS, located at longitude 27°55′00″E and latitude 26°09′30″S in Davidsonville (Roodepoort, west of Johannesburg, South Africa was measured. This was done using ICP-MS spectrometry and substantial differences were observed in the soil-plant transfer factor (TF values between these radionuclides. The plant species E. globulus exhibited the highest uptake of 238U, with an average TF of 3.97, while that of H. filipendula was 0.01 and the lowest TF of 0.15 × 10−2 was measured for A. mearnsii. However, in the case of 232Th, the highest average TF was observed for A. mearnsii (0.29, followed by E. globulus (0.10 and lowest was measured for H. filipendula (0.27 × 10−2. The ratio of TF average value i.e., 238U to 232Th in the soil-plant leaves was 38.05 for E. globulus, 0.01 for A. mearnsii and 4.38 for H. filipendula.

  9. The study of the (α, α'f) reaction at 120 MeV on 232Th and 238U (II) : Fission barrier properties deduced from fission probabilities and angular distributions

    NARCIS (Netherlands)

    Plicht, J. van der; Harakeh, M.N.; van der Woude, Adriaan; David, P.; Debrus, J.; Janszen, H.; Schulze, J.

    1981-01-01

    The fission probabilities and angular distributions of the fission fragments for the (α, α'f) reaction on 232Th and 238U at a bombarding energy of 120 MeV have been measured from about 4 to 14 MeV excitation energy. Evidence for sub-barrier resonances has been found, the negative parity ones occurri

  10. The study of the (α, α’f) reaction at 120 MeV on 232Th and 238U (I) : Fission probabilities and angular distributions in the region of the giant quadrupole resonances

    NARCIS (Netherlands)

    Plicht, J. van der; Harakeh, M.N.; van der Woude, Adriaan; David, P.; Debrus, J.; Janszen, H.; Schulze, J.

    1980-01-01

    The fission decay channel of 232Th and 238U has been investigated, using the (α, α’f) reaction at 120 MeV bombarding energy. The angular distributions of the fission fragments and the fission probabilities up to around 15 MeV excitation have been measured. No evidence for the fission decay of the gi

  11. Chemical fertilizers as a source of (238)U, (40)K, (226)Ra, (222)Rn, and trace metal pollutant of the environment in Saudi Arabia.

    Science.gov (United States)

    Alshahri, Fatimh; Alqahtani, Muna

    2015-06-01

    The specific activities of (238)U, (226)Ra, (40)K, and (222)Rn in chemical fertilizers were measured using gamma ray spectrometer and Cr-39 detector. In this study, 21 chemical fertilizers were collected from Eastern Saudi Arabian markets. The specific activities of (238)U ranged from 23 ± 0.5 to 3900 ± 195 Bq kg(-1); (226)Ra ranged from 5.60 ± 2.80 to 392 ± 18 Bq kg(-1); and (40)K ranged from 18.4 ± 3 to 16,476 ± 820 Bq kg(-1). The radon concentrations and the radon exhalation rates were found to vary from 3.20 ± 1.20 to 1532 ± 160 Bq m(-3) and from 1.60 to 774 mBq m(-2) h(-1), respectively. Radium equivalent activities (Raeq) were calculated for the analyzed samples to assess the radiation hazards arising due to the use of these chemical fertilizers in the agriculture soil. The Raeq for six local samples (nitrogen, phosphorous, and potassium (NPK) and single superphosphate (SSP)) and one imported sample (Sulfate of Potash (SOP)) were greater than the acceptable value 370 Bq kg(-1). The total air absorbed doses rates in air 1 m above the ground (D) were calculated for all samples. All samples, except one imported granule sample diammonium phosphate (DAP), were higher than the estimated average global terrestrial radiation of 55 nGy h(-1). The highest annual effective dose was in triple super phosphate (TSP) fertilizers (2.1 mSv y(-1)). The results show that the local TSP, imported SOP, and local NPK (sample 13) fertilizers were unacceptable for use as fertilizers in agricultural soil. Furthermore, the toxic elements and trace metals (Pb, Cd, Cr, Co, Ni, Hg, and As) were determined using atomic absorption spectrometer. The concentrations of chromium in chemical fertilizers were higher than the global values.

  12. RAPID QUANTITATION OF URANIUM FROM MIXED FISSION PRODUCT SAMPLES

    Energy Technology Data Exchange (ETDEWEB)

    Haney, Morgan M.; Seiner, Brienne N.; Finn, Erin C.; Friese, Judah I.

    2016-03-09

    Chemical similarities between U(VI) and Mo(VI) create challenges for separation and quantification of uranium from a mixed fission product sample. The purpose of this work was to demonstrate the feasibility of using Eichrom’s® UTEVA resin in addition to a tellurium spontaneous deposition to improve the quantitation of 235U using gamma spectroscopy. The optimized method demonstrated a consistent chemical yield of 74 ± 3 % for uranium. This procedure was evaluated using 1.41x1012 fissions produced from an irradiated HEU sample. The uranium was isotopically yielded by HPGe, and the minimum detectable activity (MDA) determined from the gamma spectra. The MDA for 235U, 237U, and 238U was reduced by a factor of two. The chemical isolation of uranium was successfully achieved in less than four hours, with a separation factor of 1.41x105 from molybdenum.

  13. Uranium isotopic fractionation factors during U(VI) reduction by bacterial isolates

    Science.gov (United States)

    Basu, Anirban; Sanford, Robert A.; Johnson, Thomas M.; Lundstrom, Craig C.; Löffler, Frank E.

    2014-07-01

    We experimentally determined the magnitude of uranium isotopic fractionation induced by U(VI) reduction by metal reducing bacterial isolates. Our results indicate that microbial U(VI) reduction induces isotopic fractionation; heavier isotopes (i.e., 238U) partition into the solid U(IV) products. The magnitudes of isotopic fractionation (expressed as ε = 1000‰ * (α-1)) for 238U/235U were 0.68‰ ± 0.05‰ and 0.99‰ ± 0.12‰ for Geobacter sulfurreducens strain PCA and strain IFRC-N, respectively. The ε values for Anaeromyxobacter dehalogenans strain FRC-W, strain FRC-R5, a novel Shewanella isolate, and Desulfitobacterium sp. strain Viet1 were 0.72‰ ± 0.15‰, 0.99‰ ± 0.12‰, 0.96‰ ± 0.16‰ and 0.86‰ ± 0.06‰, respectively. Our results show that the maximum ε values of ∼1.0‰ were obtained with low biomass (∼107 cells/mL) and low electron donor concentrations (∼500 μM). These results provide an initial assessment of 238U/235U shifts induced by microbially-mediated U(VI) reduction, which is needed as 238U/235U data are increasingly applied as redox indicators in various geochemical settings.

  14. Uranium and radium-226 in the environment of the post-uranium mining areas in Poland

    Energy Technology Data Exchange (ETDEWEB)

    Kardas, M.; Suplinska, M.; Ciupek, K. [Central Laboratory for Radiological Protection (Poland)

    2014-07-01

    The work carried out under the project NCBiR - 'Technologies Supporting Development of Safe Nuclear Power Engineering'; Task 3: Meeting the Polish nuclear power engineering's demand for fuel - fundamental aspects. Depending on location, environmental components may have different concentration levels of radionuclides. Main source of uranium and radium in the natural environment is atmospheric precipitation of the material resulting weathering and erosion of older rocks, enhanced due to human activity by fertilizers used in agriculture and fossil fuel combustion. The waste heaps and dumps, especially derived from post-uranium mining and phosphate fertilizer industry are the another source of uranium and radium in the environment. Our studies include post-uranium mining areas (inactive mines and waste dumps) and those adjacent meadows and grassland at the area of the Giant Mountains (Karkonosze Mountains) in the south-west Poland. Samples of soil and mineral material from mine shafts, water samples from ponds, streams and small rivers and vegetation samples (grass, alfalfa, birch leaves) were analyzed. Also, similar samples from agricultural regions of Poland were examined as a reference level. Uranium isotopes were determined by radiochemical method (ion exchange and extraction) and activity measurement using alpha spectrometry. Concentration of {sup 226}Ra was determined radiochemically using emanation method. For the validation of the method, determinations of uranium isotopes and radium-226 in reference samples were performed. Depending on location, the different levels of activity concentration of analyzed radionuclides were detected. Samples from the mine shafts and dumps, both water and soil, were characterized by the activity concentrations of {sup 238}U and {sup 226}Ra even by several orders higher than outside of those areas. The concentrations of the radionuclides in the areas located in further distances from mine and dumps are similar to

  15. Measurement and Analysis of Fission Rates in a Spherical Mockup of Uranium and Polyethylene

    CERN Document Server

    Tong-Hua, Zhu; Xin-Xin, Lu; Rong, Liu; Zi-Jie, Han; Li, Jiang; Mei, Wang

    2013-01-01

    Measurements of the reaction rate distribution were carried out using two kinds of Plate Micro Fission Chamber(PMFC). The first is a depleted uranium chamber and the second an enriched uranium chamber. The material in the depleted uranium chamber is strictly the same as the material in the uranium assembly. With the equation solution to conduct the isotope contribution correction, the fission rate of 238U and 235U were obtained from the fission rate of depleted uranium and enriched uranium. And then, the fission count of 238U and 235U in an individual uranium shell was obtained. In this work, MCNP5 and continuous energy cross sections ENDF/BV.0 were used for the analysis of fission rate distribution and fission count. The calculated results were compared with the experimental ones. The calculation of fission rate of DU and EU were found to agree with the measured ones within 10% except at the positions in polyethylene region and the two positions near the outer surface. Beacause the fission chamber was not co...

  16. Environmental consequences of uranium atmospheric releases from fuel cycle facility: II. The atmospheric deposition of uranium and thorium on plants.

    Science.gov (United States)

    Pourcelot, L; Masson, O; Renaud, P; Cagnat, X; Boulet, B; Cariou, N; De Vismes-Ott, A

    2015-03-01

    Uranium and thorium isotopes were measured in cypress leaves, wheat grains and lettuce taken in the surroundings of the uranium conversion facility of Malvési (South of France). The comparison of activity levels and activity ratios (namely (238)U/(232)Th and (230)Th/(232)Th) in plants with those in aerosols taken at this site and plants taken far from it shows that aerosols emitted by the nuclear site (uranium releases in the atmosphere by stacks and (230)Th-rich particles emitted from artificial ponds collecting radioactive waste mud) accounts for the high activities recorded in the plant samples close to the site. The atmospheric deposition process onto the plants appears to be the dominant process in plant contamination. Dry deposition velocities of airborne uranium and thorium were measured as 4.6 × 10(-3) and 5.0 × 10(-3) m s(-1), respectively.

  17. Uranium isotopes in groundwater from the continental intercalaire aquifer in Algerian Tunisian Sahara (Northern Africa).

    Science.gov (United States)

    Chkir, N; Guendouz, A; Zouari, K; Hadj Ammar, F; Moulla, A S

    2009-08-01

    The disequilibrium between (234)U and (238)U is commonly used as a tracer of groundwater flow. This paper aims to identify uranium contents and uranium isotopic disequilibria variation in groundwater sampled from deep Continental Intercalaire aquifer (southern Algeria and Tunisia). Large variations in both U contents (0.006-3.39ppb) and (234)U/(238)U activity ratios (0.4-15.38) are observed. We conduct a first assessment in order to verify whether the results of our investigation support and complete previous hydrogeological and isotopic studies. The dissolved U content and (234)U/(238)U activity ratio data were plotted on a two-dimensional diagram that was successfully utilized on sharing the CI aquifer into different compartments submitted to different oxidising/reducing conditions and leads also to distinguished two preferential flow paths in the Nefzaoua/Chott Fejej discharge area. Uranium isotopes disequilibrium indicate that ranium chemistry is mainly controlled by water-rock interaction enhanced by long residence time recognised for this aquifer.

  18. Determination of Fission Product Yields of 235U, 238U and 239Pu for Neutron Energies from 0.5 to 14.8 MeV

    Science.gov (United States)

    Gooden, Matthew; Arnold, Charles; Becker, John; Bhatia, Chitra; Bhike, Megha; Fowler, Malcolm; Howell, Calvin; Kelley, John; Stoyer, Mark; Tonchev, Anton; Tornow, Werner; Vieira, Dave; Wilhelmy, Jerry

    2014-03-01

    A joint TUNL-LANL-LLNL collaboration has been formed to study the issue of possible energy dependences for certain fission product isotopes. Work has been carried out at the TUNL 10 MV Tandem accelerator which produces nearly mono-energetic neutrons via either 2H(d,n)3He,3H(d,n)4He,or3H(p,n)3He reactions. Three dual fission ionization chambers dedicated to 235U, 238U and 239Pu thick target foils and thin monitor foils respectively, were exposed to the neutron beams. After irradiation, thick target foils were gamma counted over a period of 1-2 months and characteristic gamma rays from fission products were recorded using HPGe detectors at TUNL's low background counting area. Using the dual fission chambers, relative fission product yield were determined at a high precision of 2-3 % as well as absolute fission product yields at a lower precision of 5-6 %. Preliminary results will be presented for a number of fission product isotopes over the incident neutron energy range of 0.5 to 14.8 MeV.

  19. Energy Dependence of Neutron-Induced Fission Product Yields of 235U, 238U and 239Pu Between 0.5 and 14.8 MeV

    Science.gov (United States)

    Gooden, Matthew; Tornow, Werner; Tonchev, Anton; Vieira, Dave; Wilhelmy, Jerry; Arnold, Charles; Fowler, Malcolm; Stoyer, Mark

    2014-09-01

    Under a joint collaboration between TUNL-LANL-LLNL, a set of absolute fission product yield measurements have been performed. The energy dependence of a number of cumulative fission products between 0.5 and 14.8 MeV have been measured using quasi-monoenergetic neutron beams for three actinide targets, 235U, 238U and 239Pu, between 0.5 and 14.8 MeV. The FPYs were measured by a combination of activation utilizing specially designed dual-fission chambers and γ-ray counting. The dual-fission chambers are back-to-back ionization chambers encasing a target with thin deposits of the same target isotope in each chamber. This method allows for the direct measurement of the fission rate in the activation target with no reference to the fission cross-section, reducing uncertainties. γ-ray counting was performed on well-shield HPGe detectors over a period of 2 months per activation to properly identify fission products. Reported are absolute cumulative fission product yields for incident neutron energies of 0.5, 1.37, 2.4, 4.6 and 14.8 MeV.

  20. Capture and Fission rate of 232-Th, 238-U, 237-Np and 239-Pu from spallation neutrons in a huge block of lead.

    CERN Document Server

    Vlachoudis, Vasilis

    2000-01-01

    The study is centered on the research of the incineration possibility of nuclear waste, by the association of a particle accelerator with a multiplying medium of neutrons, in the project "Energy Amplifier" of C. Rubbia. It consists of the experimental determination of the rates of capture and fission of certain elements (232-Th, 238-U, 237-Np and 239-Pu) subjected to a fluence of fast spallation neutrons. These neutrons are produced by the interaction of high kinetic energy protons (several GeV) provided by the CERN-PS accelerator, on a large lead solid volume. The measurement techniques used in this work, are based on the activation of elements in the lead volume and the subsequent gamma spectroscopy of the activated elements, and also by the detection of fission fragment traces. The development, of a Monte Carlo code makes it possible, on one hand, to better understand the relevant processes, and on the other hand, to validate the code, by comparison with measurements, for the design and the construction of...

  1. Vertical and horizontal distribution of radionuclides ({sup 232}Th, {sup 238}U and {sup 40}K) in sediment from Manjung coastal water area Perak, Malaysia

    Energy Technology Data Exchange (ETDEWEB)

    Abdullah, Anisa, E-mail: coppering@ymail.com; Hamzah, Zaini; Wood, Ab. Khalik [Faculty of Applied Sciences, Universiti Teknologi MARA, 40450, Shah Alam, Selangor (Malaysia); Saat, Ahmad [Faculty of Applied Sciences, Universiti Teknologi MARA, 40450, Shah Alam, Selangor (Malaysia); Institute of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia)

    2016-01-22

    Distribution of radionuclides from anthropogenic activities has been widely studied in marine coastal area. Due to rapid population growth and socio-economic development in Manjung area such as coal fired power plant, iron foundries, port development, waste discharged from factories and agriculture runoff may contribute to increase in pollution rate. The radioactive materials from anthropogenic activities could deteriorate the quality of the marine ecosystem and thus lead to possible radiological health risk to the population. Radionuclides ({sup 232}Th, {sup 238}U and {sup 40}K) content in surface and profile sediment from Manjung coastal area was determined in this study. Radionuclides in sediment from seven locations were collected using sediment core sampling and measurements were carried out using Energy Dispersive X-ray Fluorescence (EDXRF) spectroscopy. The results show that the concentration of radionuclides in surface sediment and distribution trend of depth vertical profile sediment generally varies depending on locations. Enrichment factors (EF), geo-accumulation index (I{sub geo}) and pollution index (PI) were applied to determine level of pollution of this study area. The radiological risks related to human exposure were evaluated based on external hazard index (H{sub ex})

  2. Vertical and horizontal distribution of radionuclides (232Th, 238U and 40K) in sediment from Manjung coastal water area Perak, Malaysia

    Science.gov (United States)

    Abdullah, Anisa; Hamzah, Zaini; Saat, Ahmad; Wood, Ab. Khalik

    2016-01-01

    Distribution of radionuclides from anthropogenic activities has been widely studied in marine coastal area. Due to rapid population growth and socio-economic development in Manjung area such as coal fired power plant, iron foundries, port development, waste discharged from factories and agriculture runoff may contribute to increase in pollution rate. The radioactive materials from anthropogenic activities could deteriorate the quality of the marine ecosystem and thus lead to possible radiological health risk to the population. Radionuclides (232Th, 238U and 40K) content in surface and profile sediment from Manjung coastal area was determined in this study. Radionuclides in sediment from seven locations were collected using sediment core sampling and measurements were carried out using Energy Dispersive X-ray Fluorescence (EDXRF) spectroscopy. The results show that the concentration of radionuclides in surface sediment and distribution trend of depth vertical profile sediment generally varies depending on locations. Enrichment factors (EF), geo-accumulation index (Igeo) and pollution index (PI) were applied to determine level of pollution of this study area. The radiological risks related to human exposure were evaluated based on external hazard index (Hex).

  3. On an Increase of Critical Current in High Temperature Superconductors Doped with $^{238}U$ Due to the Production of Nuclear Photofission Fragment Tracks

    CERN Document Server

    Goncharov, I N

    2001-01-01

    The effect of appreciable increasing J_c(B,T) in HTSC (especially at liquid nitrogen temperatures of 62-78 K and magnetic fields of above 0.5 T) due to the production of fast heavy ion tracks, including those of doped U nuclear fission fragments, is known. The tracks are additional effective pinning-centers. The results described in the literature have been obtained for {235}U doped HTSC after reactor thermal neutron irradiations. Disadvantages of such a method are analyzed in this paper, in particular in case of its use for current-carrying Bi-2223/Ag tape, because a very high radioactivity level slowly decreasing in time arises. The author has suggested to use {238}U nuclear photofission in over a giant resonance energy range (E_gamma ~10-20 MeV). The experimental results obtained after tape irradiation with gamma-quanta (E_gamma \\leq 24 MeV), including a time dependence of radioactivity level, are presented. Possibilities of practical realization of this method are discussed.

  4. Observation of new neutron-rich micro-second isomers among fission products of ^238U at 345 MeV/u

    Science.gov (United States)

    Kameda, Daisuke; Nakao, Taro; Kubo, Toshiyuki; Ohnishi, Tetsuya; Takeda, Hiroyuki; Fukuda, Naoki; Kusaka, Kensuke; Yoshida, Atsushi; Yoshida, Koichi; Ohtake, Masao; Inabe, Naohito; Yanagisawa, Yoshiyuki; Tanaka, Kanenobu; Gono, Yasuyuki

    2009-10-01

    In the production of the radioactive isotope (RI) beam using projectile fragment separators, γ rays emitted from metastable states, isomers, of the reaction products can be used as a fingerprint of the isotope that is analyzed in the separator. In the operation of the superconducting in-flight RI beam separator BigRIPS [1] at RIKEN RI Beam Factory, the detection of such γ rays plays important roles not only in the identification of the RI beam [2] but also in searching for new isomers, providing valuable spectroscopic information on the isotopes. In the recent new-isotope production experiment with BigRIPS using in-flight fission of 345 MeV/nucleon ^238U at the beam intensity around 0.3 pnA, we have observed a number of short-lived isomeric decays which include unknown decays from more than 10 isotopes, using three clover-type Ge detectors with a beam stopper of aluminum. The primal result of the observations will be reported. [1] T. Kubo: Nucl. Instr. and Meth. B 204 (2003) 97. [2] T. Ohnishi et al.: J. Phys. Soc. Japan, 77 (2008) 083201.

  5. Investigating uranium distribution in surface sediments and waters: a case study of contamination from the Juniper Uranium Mine, Stanislaus National Forest, CA.

    Science.gov (United States)

    Kayzar, Theresa M; Villa, Adam C; Lobaugh, Megan L; Gaffney, Amy M; Williams, Ross W

    2014-10-01

    The uranium concentrations and isotopic compositions of waters, sediment leachates and sediments from Red Rock Creek in the Stanislaus National Forest of California were measured to investigate the transport of uranium from a point source (the Juniper Uranium Mine) to a natural surface stream environment. The ((234)U)/((238)U) composition of Red Rock Creek is altered downstream of the Juniper Mine. As a result of mine-derived contamination, water ((234)U)/((238)U) ratios are 67% lower than in water upstream of the mine (1.114-1.127 ± 0.009 in the contaminated waters versus 1.676 in the clean branch of the stream), and sediment samples have activity ratios in equilibrium in the clean creek and out of equilibrium in the contaminated creek (1.041-1.102 ± 0.007). Uranium concentrations in water, sediment and sediment leachates are highest downstream of the mine, but decrease rapidly after mixing with the clean branch of the stream. Uranium content and compositions of the contaminated creek headwaters relative to the mine tailings of the Juniper Mine suggest that uranium has been weathered from the mine and deposited in the creek. The distribution of uranium between sediment surfaces (leachable fraction) and bulk sediment suggests that adsorption is a key element of transfer along the creek. In clean creek samples, uranium is concentrated in the sediment residues, whereas in the contaminated creek, uranium is concentrated on the sediment surfaces (∼70-80% of uranium in leachable fraction). Contamination only exceeds the EPA maximum contaminant level (MCL) for drinking water in the sample with the closest proximity to the mine. Isotopic characterization of the uranium in this system coupled with concentration measurements suggest that the current state of contamination in Red Rock Creek is best described by mixing between the clean creek and contaminated upper branch of Red Rock Creek rather than mixing directly with mine sediment.

  6. Using Uranium-series isotopes to understand processes of rapid soil formation in tropical volcanic settings: an example from Basse-Terre, French Guadeloupe

    Science.gov (United States)

    Ma, Lin

    2015-04-01

    Lin Ma1, Yvette Pereyra1, Peter B Sak2, Jerome Gaillardet3, Heather L Buss4 and Susan L Brantley5, (1) University of Texas at El Paso, El Paso, TX, United States, (2) Dickinson College, Carlisle, PA, United States, (3) Institute de Physique d Globe Paris, Paris, France, (4) University of Bristol, Bristol, United Kingdom, (5) Pennsylvania State University Main Campus, University Park, PA, United States Uranium-series isotopes fractionate during chemical weathering and their activity ratios can be used to determine timescales and rates of soil formation. Such soil formation rates provide important information to understand processes related to rapid soil formation in tropical volcanic settings, especially with respect to their fertility and erosion. Recent studies also highlighted the use of U-series isotopes to trace and quantify atmospheric inputs to surface soils. Such a process is particularly important in providing mineral nutrients to ecosystems in highly depleted soil systems such as the tropical soils. Here, we report U-series isotope compositions in thick soil profiles (>10 m) developed on andesitic pyroclastic flows in Basse-Terre Island of French Guadeloupe. Field observations have shown heterogeneity in color and texture in these thick profiles. However, major element chemistry and mineralogy show some general depth trends. The main minerals present throughout the soil profile are halloysite and gibbsite. Chemically immobile elements such as Al, Fe, and Ti show a depletion profile relative to Th while elements such as K, Mn, and Si show a partial depletion profile at depth. Mobile elements such as Ca, Mg, and Sr have undergone intensive weathering at depths, and an addition profile near the surface, most likely related to atmospheric inputs. (238U/232Th) activity ratios in one soil profile from the Brad David watershed in this study ranged from 0.374 to 1.696, while the (230Th/232Th) ratios ranged from 0.367 to 1.701. A decrease of (238U/232Th) in the

  7. Determination of concentrations and isotopic ratio of uranium in groundwaters drawn from two deep wells drilled in granitic rocks belonging to Itu intrusive suite; Determinacao das concentracoes e razoes isotopicas de uranio em aguas subterraneas extraidas de pocos perfurados em rochas da suite intrusiva de Itu (SP)

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Francisca de; Reyes, Erika; Marques, Leila Soares [Sao Paulo Univ., SP (Brazil). Inst. de Astronomia, Geofisica e Ciencias Atmosfericas. Dept. de Geofisica]. E-mail: francisca@iag.usp.br; erika@iag.usp.br; leila@iag.usp.br

    2005-07-01

    This paper presents the first results obtained in the determination of dissolved uranium concentrations and ({sup 234}U/{sup 238}U) activity ratios of groundwaters drawn from two deep wells drilled in granitic rocks belonging to Itu Intrusive Suite, which is located at eastern Sao Paulo State. One of the wells, whose groundwaters have been analyzed, is located in Salto Town, while the other one is located in Itu Town. The groundwater sampling is monthly and begun on September, 2004, in order to investigate possible sazonal variations. The alpha spectrometry technique, associated with isotopic dilution method, has been used for these determinations. The data obtained up to now show that the groundwaters from Salto present uranium concentrations significantly lower ((0.098 {+-} 0.007) - (0.17 {+-} 0.01) ng/g) than those from Itu ((0.22 {+-} 0.02) - (0.31 {+-} 0.02) ng/g). The {sup 234}U and {sup 238}U isotopes of the investigated groundwaters from both wells are in radioactive disequilibrium, with ({sup 234}U/{sup 238}U) activity ratios systematically higher than unity. Although the groundwaters from Salto well are characterized by low {sup 234}U and {sup 238}U specific activities they present higher ({sup 234}U/{sup 238}U) activity ratios than those from Itu. The observed differences on the behavior of uranium concentrations and ({sup 234}U/{sup 238}U) activity ratios in the groundwaters from the two wells are very probably due to the large variety of granitic rocks from Itu Intrusive Suite, which are characterized by distinct uranium abundances. (author)

  8. Isotopic characterization of uranium in soils of the Ipanema National Forest (FLONA-Ipanema); Caracterizacao isotopica de uranio em solos da Floresta Nacional de Ipanema (FLONA-Ipanema)

    Energy Technology Data Exchange (ETDEWEB)

    Silva, F.B.; Marques, F.H., E-mail: fernandobaliani@yahoo.com.br, E-mail: fernando_henrique06@hotmail.com [Laboratorio de Pocos de Caldas (LAPOC/CNEN-MG), Pocos de Caldas, MG (Brazil); Enzweiler, J.; Ladeira, F.S.B., E-mail: Jacinta@ige.unicamp.br, E-mail: fsbladeira@ige.unicamp.br [Universidade Estadual de Campinas (UNICAMP), Campinas, SP (Brazil). Instituto de Geociencias

    2015-07-01

    The National Forest of Ipanema (FLONA) is situated on a geological anomaly, known as 'Domo de Aracoiaba'. The soils of the area include Oxisols, Inceptsols and Alfisols. The amount of uranium and respective isotope activities in a soil depend on the parental rock and on the pedologic processes. The aim of this study was to investigate the activities for uranium isotopes ({sup 238}U, {sup 234}U, {sup 235}U) and the activity ratio (AR) {sup 234}U/ {sup 238}U or secular equilibrium for different soil types of the area collected at horizons A and B. The amount of uranium showed no significant differences for soils generated from alkaline intrusive rocks and sandstone, however, secular equilibrium was observed for Oxisol (RA = 1), while Inceptsol presented RA> 1 and the other soils, Alfisols, presented RA values <1. (author)

  9. Uranium Isotope Evidence for Temporary Ocean Oxygenation Following the Sturtian Glaciation

    Science.gov (United States)

    Lau, K. V.; Maher, K.; Macdonald, F. A.; Payne, J.

    2015-12-01

    The link between widespread ocean oxygenation in the Neoproterozoic and the rise of animals has long been debated, largely because the timing and nature of oxygenation of the oceans remain poorly constrained. Strata deposited during the Cryogenian non-glacial interlude (660 to 635 Ma), between the Sturtian and Marinoan Snowball Earth glaciations, contain the earliest fossil evidence of animals. To quantitatively estimate patterns of seafloor oxygenation during this critical interval, we present uranium isotope (δ238U) data from limestone of the Taishir Formation (Fm) in Mongolia in two stratigraphic sections that are separated by ~75 km across the basin. The Taishir Fm hosts two large δ13C excursions that co-vary in total organic and inorganic (carbonate) carbon: a basal carbonate δ13C excursion to -4‰ in the Sturtian cap carbonate, followed by a rise to enriched values of +8‰, a second negative δ13C excursion to -7‰ referred to as the Taishir excursion, followed by a second rise to +10‰. Above the Sturtian glacial deposits, in the stratigraphic interval below the Taishir excursion, δ238U compositions have a mean value that is similar to that of modern seawater. After the Taishir excursion, the δ238U record exhibits a step decrease of ~0.3‰, and δ238U remains approximately constant until the erosional unconformity at the base of the Marinoan glacial deposits. We use a box model to constrain the uranium cycle behavior that best explains our observations. In the model, the best explanation for the less negative post-Sturtian values of δ238U is extensive oxygenation of the seafloor. Moreover, the model demonstrates that the higher δ238U values of the post-Sturtian limestones are inconsistent with an increased flux of uranium to the oceans due to post-Snowball weathering as the primary driver of the excursion. Thus, we favor a scenario in which there was a rise in oxygen levels following the Sturtian glaciation followed by a decrease in seafloor

  10. Distribution of uranium isotopes in surface water of the Llobregat river basin (Northeast Spain)

    Energy Technology Data Exchange (ETDEWEB)

    Camacho, A.; Devesa, R.; Valles, I.; Serrano, I.; Soler, J.; Blazquez, S.; Ortega, X.; Matia, L. [University of Politecn Cataluna, Barcelona (Spain)

    2010-12-15

    A study is presented on the distribution of U-234, U-238, U-235 isotopes in surface water of the Llobregat river basin (Northeast Spain), from 2001 to 2006. Sixty-six superficial water samples were collected at 16 points distributed throughout the Llobregat river basin. Uranium isotopes were measured by alpha spectrometry (PIPS detectors). The test procedure was validated according to the quality requirements of the ISO17025 standard. The activity concentration for the total dissolved uranium ranges from 20 to 261 mBq L{sup -1}. The highest concentrations of uranium were detected in an area with formations of sedimentary rock, limestone and lignite. A high degree of radioactive disequilibrium was noted among the uranium isotopes. The U-234/R-238 U activity ratio varied between 1.1 and 1.9 and the waters with the lowest uranium activity registered the highest level of U-234/U-238 activity ratio. Correlations between uranium activity in the tested water and chemical and physical characteristics of the aquifer were found.

  11. The effect of pH and time on the extractability and speciation of uranium(VI) sorbed to SiO2.

    Science.gov (United States)

    Ilton, Eugene S; Wang, Zheming; Boily, Jean-François; Qafoku, Odeta; Rosso, Kevin M; Smith, Steven C

    2012-06-19

    The effect of pH and contact time on uranium extractability from quartz surfaces was investigated using either acidic or carbonate (CARB) extraction solutions, time-delayed spikes of different U isotopes ((238)U and (233)U), and liquid helium temperature time-resolved laser-induced fluorescence spectroscopy (TRLFS). Quartz powders were reacted with (238)U(VI) bearing solutions equilibrated with atmospheric CO(2) at pH 6, 7, and 8. After 42 days, the suspensions were spiked with (233)U(VI) and reacted for an additional 7 days. Sorbed U was then extracted with either dilute nitric acid or CARB. For the CARB, but not the acid, extraction there was a systematic decrease in extraction efficiency for both isotopes from pH 6 to 8, which was mimicked by less desorption of (238)U, after the (233)U spike, from pH 6 to 8. The efficiency of (233)U extraction was consistently greater than that of (238)U, indicating a strong temporal component to the strength of U association with the surface that was accentuated with increasing pH. TRLFS revealed a strong correlation between CARB extraction efficiency and sorbed U speciation as a function of pH and time. Collectively, the observations show that aging and pH are critical factors in determining the form and strength of uranium-silica interactions.

  12. Estimation of uranium migration parameters in sandstone aquifers.

    Science.gov (United States)

    Malov, A I

    2016-03-01

    The chemical composition and isotopes of carbon and uranium were investigated in groundwater samples that were collected from 16 wells and 2 sources in the Northern Dvina Basin, Northwest Russia. Across the dataset, the temperatures in the groundwater ranged from 3.6 to 6.9 °C, the pH ranged from 7.6 to 9.0, the Eh ranged from -137 to +128 mV, the total dissolved solids (TDS) ranged from 209 to 22,000 mg L(-1), and the dissolved oxygen (DO) ranged from 0 to 9.9 ppm. The (14)C activity ranged from 0 to 69.96 ± 0.69 percent modern carbon (pmC). The uranium content in the groundwater ranged from 0.006 to 16 ppb, and the (234)U:(238)U activity ratio ranged from 1.35 ± 0.21 to 8.61 ± 1.35. The uranium concentration and (234)U:(238)U activity ratio increased from the recharge area to the redox barrier; behind the barrier, the uranium content is minimal. The results were systematized by creating a conceptual model of the Northern Dvina Basin's hydrogeological system. The use of uranium isotope dating in conjunction with radiocarbon dating allowed the determination of important water-rock interaction parameters, such as the dissolution rate:recoil loss factor ratio Rd:p (a(-1)) and the uranium retardation factor:recoil loss factor ratio R:p in the aquifer. The (14)C age of the water was estimated to be between modern and >35,000 years. The (234)U-(238)U age of the water was estimated to be between 260 and 582,000 years. The Rd:p ratio decreases with increasing groundwater residence time in the aquifer from n × 10(-5) to n × 10(-7) a(-1). This finding is observed because the TDS increases in that direction from 0.2 to 9 g L(-1), and accordingly, the mineral saturation indices increase. Relatively high values of R:p (200-1000) characterize aquifers in sandy-clayey sediments from the Late Pleistocene and the deepest parts of the Vendian strata. In samples from the sandstones of the upper part of the Vendian strata, the R:p value is ∼ 24, i.e., sorption processes are

  13. Natural uranium and thorium isotopes in sediment cores off Malaysian ports

    Science.gov (United States)

    Yusoff, Abdul Hafidz; Sabuti, Asnor Azrin; Mohamed, Che Abd Rahim

    2015-06-01

    Sediment cores collected from three Malaysian marine ports, namely, Kota Kinabalu, Labuan and Klang were analyzed to determine the radioactivities of 234U, 238U, 230Th, 232Th and total organic carbon (TOC) content. The objectives of this study were to determine the factors that control the activity of uranium isotopes and identify the possible origin of uranium and thorium in these areas. The activities of 234U and 238U show high positive correlation with TOC at the middle of sediment core from Kota Kinabalu port. This result suggests that activity of uranium at Kota Kinabalu port was influenced by organic carbon. The 234U/238U value at the upper layer of Kota Kinabalu port was ≥1.14 while the ratio value at Labuan and Klang port was ≤ 1.14. These results suggest a reduction process occurred at Kota Kinabalu port where mobile U(VI) was converted to immobile U(IV) by organic carbon. Therefore, it can be concluded that the major input of uranium at Kota Kinabalu port is by sorptive uptake of authigenic uranium from the water column whereas the major inputs of uranium to Labuan and Klang port are of detrital origin. The ratio of 230Th/232Th was used to estimate the origin of thorium. Low ratio value (lt; 1.5) at Labuan and Klang ports support the suggestion that thorium from both areas were come from detrital input while the high ratio (> 1.5) of 230Th/232Th at Kota Kinabalu port suggest the anthropogenic input of 230Th to this area. The source of 230Th is probably from phosphate fertilizers used in the oil-palm cultivation in Kota Kinabalu that is adjacent to the Kota Kinabalu port.

  14. The Role of Plants in the 238U-234U Disequilibria of Stream Waters: The Example of the Strengbach Watershed (Vosges, France)

    Science.gov (United States)

    Pierret, M.; Chbaaux, F.

    2004-12-01

    Recent TIMS or MC ICPMS analyses of U disequilibria in the dissolved load of stream and river waters have confirmed the potential of the U activity ratio in river waters as a specific tracer of chemical fluxes coming from rocks and soils (e.g., 1). These precise measurements have also outlined that occurrence of U activity ratios lower than one in dissolved load of river waters is not exceptional, especially at the scale of small watersheds. Such U values pose in turn the question of the real mechanisms controlling the supply of 234U-238U isotopes to the freshwaters. In order to address this question U activity ratios, Sr isotope ratios and the concentrations of major and some trace elements were analyzed in the different compartments of a small granitic watershed: the Strengbach environmental observatory (Vosges, France) ( http://ohge.u-strasbg.fr). In addition of the different streamwaters draining this watershed, the main horizons of weathering profiles, the associated soil solutions and the main tree species growing around were analyzed. The data confirm that the Strengbach stream water samples have generally U activity ratios lower than one and point out that soils solutions display a similar range of U and Sr variations. By contrast, tree and plant samples define different trends of variation in a plot of U activity ratios against Sr isotope ratios with, above all, U activity ratios systematically greater than one. These data show that trees and plants collected during this work cannot directly pomp their nutriments from soils and soil solutions sampled here, i.e. gravity solutions. They also suggest that, in this watershed, the plants, especially trees, play a central role in the weathering processes of rocks and minerals, and control a large part of the geochemical signature of the water samples collected on this watershed, including their U activity ratios. 1Riotte J and Chabaux F. (1999) GCA 63, 1263-1275.

  15. Measurement of 238U and 232Th in Petrol, Gas-oil and Lubricant Samples by Using Nuclear Track Detectors and Resulting Radiation Doses to the Skin of Mechanic Workers.

    Science.gov (United States)

    Misdaq, M A; Chaouqi, A; Ouguidi, J; Touti, R; Mortassim, A

    2015-10-01

    Workers in repair shops of vehicles (cars, buses, truck, etc.) clean carburetors, check fuel distribution, and perform oil changes and greasing. To explore the exposure pathway of (238)U and (232)Th and its decay products to the skin of mechanic workers, these radionuclides were measured inside petrol, gas-oil, and lubricant material samples by means of CR-39 and LR-115 type II solid state nuclear track detectors (SSNTDs), and corresponding annual committed equivalent doses to skin were determined. The maximum total equivalent effective dose to skin due to the (238)U and (232)Th series from the application of different petrol, gas-oil, and lubricant samples by mechanic workers was found equal to 1.2 mSv y(-1) cm(-2).

  16. Radioecology studies in the vicinity of a closed uranium mine

    Directory of Open Access Journals (Sweden)

    Černe M.

    2012-04-01

    Full Text Available Although the influential area of the former uranium mine at Zirovski vrh, Slovenia has been under continuous radiological monitoring, more detailed radioecology studies, focused on assessing mobility and bioavailability of deposited radionuclides, were initiated about five years ago. The mobility of 238U, 234U, 230Th and 226Ra was studied applying two sequential extraction protocols. The results revealed that both sequential extraction protocols are not comparable as the data obtained are protocol- and radionuclide-dependent. It was found that the most mobile ones were uranium isotopes, followed by 226Ra and 230Th. In addition, uptake of particular radionuclides by the wetland plants (Molinia arundinacea, Juncus effusus and Caltha palustris grown in soils contaminated with seepage waters from the tailings was studied. The plants contained higher levels of 238U, 226Ra and 230Th compared to the plants from the control site. Activity concentration of 226Ra was the highest for all three plant species. Activity concentration of natural radionuclides in milk collected from the area of Zirovski vrh was comparable to the reference location, except for uranium where the content was higher. The combined annual effective dose for adults consuming milk from the Zirovski vrh area is 13 ± 2 μSv yr−1.

  17. Development of U isotope fractionation as an indictor or U(VI) reduction in uranium plumes

    Energy Technology Data Exchange (ETDEWEB)

    Lundstrom, Craig [Univ. of Illinois, Urbana-Champaign, IL (United States); Johnson, Thomas [Univ. of Illinois, Urbana-Champaign, IL (United States)

    2016-02-16

    This is the final report for a university research project that advanced development of a new technology for identifying chemical reduction of uranium contamination in groundwater at the Rifle Field Challenge site. Reduction changes mobile hexavalent uranium into immobile U(IV). The stable isotope ratio (238U/235U) measurements of U using multicollector ICP-mass spectrometry were performed to understand the chemical reduction and sorption processes during various field experiments. In addition laboratory experiments were performed to better understand the isotopic fractionations. The main objectives of this project were completed during the project period and two peer-reviewed articles were published to disseminate the information gained.

  18. Origin of uranium isotope variations in early solar nebula condensates.

    Science.gov (United States)

    Tissot, François L H; Dauphas, Nicolas; Grossman, Lawrence

    2016-03-01

    High-temperature condensates found in meteorites display uranium isotopic variations ((235)U/(238)U), which complicate dating the solar system's formation and whose origin remains mysterious. It is possible that these variations are due to the decay of the short-lived radionuclide (247)Cm (t 1/2 = 15.6 My) into (235)U, but they could also be due to uranium kinetic isotopic fractionation during condensation. We report uranium isotope measurements of meteoritic refractory inclusions that reveal excesses of (235)U reaching ~+6% relative to average solar system composition, which can only be due to the decay of (247)Cm. This allows us to constrain the (247)Cm/(235)U ratio at solar system formation to (1.1 ± 0.3) × 10(-4). This value provides new clues on the universality of the nucleosynthetic r-process of rapid neutron capture.

  19. Origin of uranium isotope variations in early solar nebula condensates

    CERN Document Server

    Tissot, Francois L H; Grossman, Lawrence

    2016-01-01

    High temperature condensates found in meteorites display uranium isotopic variations (235U/238U) that complicate dating of the formation of the Solar System and whose origin remains mysterious. It is possible that these variations are due to decay of the short-lived radionuclide 247Cm (t1/2=15.6 Myr) into 235U but they could also be due to uranium kinetic isotopic fractionation during condensation. We report uranium isotope measurements of meteoritic refractory inclusions that reveal excesses of 235U reaching ~+6 % relative to average solar system composition, which can only be due to decay of 247Cm. This allows us to constrain the 247Cm/235U ratio at Solar System formation to (1.1 +- 0.3) x 10-4. This value provides new clues on the universality of nucleosynthetic r-process of rapid neutron capture.

  20. A rapid method for determination of the isotopic composition of uranium samples by alpha spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Martin Sanchez, A.; Tome, F.V.; Diaz Bejarano, J.; Jurado Vargas, M. (Dept. de Fisica, Univ. Extremadura, Badajoz (Spain))

    1992-03-01

    A simple method of analyzing alpha spectra from natural and enriched or depleted uranium samples is developed. The procedure is non-iterative, and takes into consideration low-energy tail and branching-ratio corrections to accurately calculate the area corresponding to each uranium isotope ({sup 234}U, {sup 235}U, {sup 236}U, {sup 238}U) in the spectrum, and then the isotopic composition of the sample. A BASIC computer program, called ENURA, has been developed to perform all the necessary calculations to give the results together with their uncertainties. Several samples were prepared with different uranium concentrations made from standard solutions with known compositions, and the method was checked against the experimental measurements from these samples. Other series of uranium spectra were theoretically constructed using a given line shape in order to cover the required range of enriched or depleted uranium. (orig.).

  1. Natural Radioactivity in Soil and Water from Likuyu Village in the Neighborhood of Mkuju Uranium Deposit

    Directory of Open Access Journals (Sweden)

    Najat K. Mohammed

    2013-01-01

    Full Text Available The discovery of high concentration uranium deposit at Mkuju, southern part of Tanzania, has brought concern about the levels of natural radioactivity at villages in the neighborhood of the deposit. This study determined the radioactivity levels of 30 soil samples and 20 water samples from Likuyu village which is 54 km east of the uranium deposit. The concentrations of the natural radionuclides 238U, 232Th, and 40K were determined using low level gamma spectrometry of the Tanzania Atomic Energy Commission (TAEC Laboratory in Arusha. The average radioactivity concentrations obtained in soil samples for 238U (51.7 Bq/kg, 232Th (36.4 Bq/kg, and 40K (564.3 Bq/kg were higher than the worldwide average concentrations value of these radionuclides reported by UNSCEAR, 2000. The average activity concentration value of 238U (2.35 Bq/L and 232Th (1.85 Bq/L in water samples was similar and comparable to their mean concentrations in the control sample collected from Nduluma River in Arusha.

  2. Alpha and gamma spectrometry for natural radioactive nuclides around uranium mines and nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, A.M.; Tome, F.V.; Bejarano, J.D.; Aparicio, A.G. (Universidad de Extremadura, Badajoz (Spain). Dept. de Fisica)

    1992-01-01

    Concentration of uranium and [sup 234]U/[sup 238]U and [sup 235]U/[sup 238]U activity ratios were studied in water samples taken in the neighbourhood of two uranium mines ('El Lobo' and 'El Pedregal', Badajoz, Spain), and around two nuclear power plants and their cooling reservoirs (the Central Nuclear de Almaraz, which is working today, and the Central Nuclear de Valdecaballeros, which is in the construction phase), using alpha spectrometry with semiconductor detectors. The Valdecaballeros data were taken to check for comparison with those of the Central Nuclear de Almaraz and with future values after the start of operation. Measurements were also made of all soluble gamma emitting nuclides using a shielded coaxial high purity germanium detector. The data suggest that the mechanisms responsible for the changes in the concentrations and in the [sup 234]U/[sup 238]U activity ratios in surface waters are principally dilution and leaching. (author).

  3. Solubility of uranium and thorium from a healing earth in synthetic gut fluids: a case study for use in dose assessments.

    Science.gov (United States)

    Höllriegl, Vera; Li, Wei Bo; Leopold, Karsten; Gerstmann, Udo; Oeh, Uwe

    2010-11-01

    The aim of this case study was to estimate the bioaccessibility of uranium ((238)U) and thorium ((232)Th) from a healing earth by analysing the solubility of these radionuclides in synthetic gastric and intestinal fluids. An easy applicable in vitro test system was used to investigate the fractional mobilization of the soil contaminants being potentially available for absorption under human in vivo conditions. These findings provided the basis for a prospective dose assessment. The solubility experiments were performed using two different in vitro digestion methods. The concentrations of (238)U and (232)Th in the solutions extracted from the soil were measured by inductively coupled plasma mass spectrometry (ICP-MS). The dissolved fractions in the synthetic gastrointestinal fluid ranged in average from 10.3% to 13.8% for (238)U and from 0.3% to 1.6% for (232)Th, respectively, depending on the digestion method. Subsequently, the committed effective doses from intake of (238)U and (232)Th after ingestion of the healing earth during 1 year were evaluated for adult persons. Thereby ingestion dose coefficients calculated as a function of bioaccessibility were used. The dose assessments ranged between 4.3 × 10(-7)-1.9 × 10(-6) Sv y(-1) for (238)U and 5.6 × 10(-7)-3.3 × 10(-6) Sv y(-1) for (232)Th, respectively. On the basis of the assumptions and estimations made, the present work indicates a relatively low radiation risk due to (238)U and (232)Th after internal exposure of the healing earth.

  4. Uranium pollution in an estuary affected by pyrite acid mine drainage and releases of naturally occurring radioactive materials.

    Science.gov (United States)

    Villa, M; Manjón, G; Hurtado, S; García-Tenorio, R

    2011-07-01

    After the termination of phosphogypsum discharges to the Huelva estuary (SW Spain), a unique opportunity was presented to study the response of a contaminated environmental compartment after the cessation of its main source of pollution. The evolution over time of uranium concentrations in the estuary is presented to supply new insights into the decontamination of a scenario affected by Naturally Occurring Radioactive Material (NORM) discharges. The cleaning of uranium isotopes from the area has not taken place as rapidly as expected due to leaching from phosphogypsum stacks. An in-depth study using various techniques of analysis, including (234)U/(238)U and (230)Th/(232)Th ratios and the decreasing rates of the uranium concentration, enabled a second source of uranium contamination to be discovered. Increased uranium levels due to acid mine drainage from pyrite mines located in the Iberian Pyrite Belt (SW Spain) prevent complete uranium decontamination and, therefore, result in levels nearly twice those of natural background levels.

  5. Eruption and magma crystallization ages of Las Tres Vírgenes (Baja California) constrained by combined 230Th/ 238U and (U-Th)/He dating of zircon

    Science.gov (United States)

    Schmitt, Axel K.; Stockli, Daniel F.; Hausback, Brian P.

    2006-11-01

    Las Tres Vírgenes volcano is a calc-alkaline composite cone located near the main Gulf of California escarpment on the E coast of the Baja California peninsula. High-sensitivity ion microprobe U-series ( 230Th/ 238U) ages for zircon from La Vírgen tephra average 121 - 10 + 12 ka (1σ; MSWD = 2.7), with discrete age peaks at ˜ 100 and 160 ka. The noble gas mass spectrometric (U-Th)/He zircon age, corrected for disequilibrium and pre-eruptive storage, is 36 ± 3 ka. This result for the eruption age of La Vírgen tephra is significantly older than previously postulated historic or Holocene ages that were based on an 18th century map reference and 14C dating of accidental charcoal, respectively. The new (U-Th)/He zircon age is consistent with a > 26 ± 4 ka age derived from cosmogenic He exposure dating of an overlying basaltic lava flow [Hausback, B.P. and Abrams, M.J., 1996. Plinian eruption of La Virgen Tephra, Volcán Las Tres Virgenes, Baja California Sur, Mexico. Eos, Transactions, American Geophysical Union, 77(46, Suppl.): 813-814.]. U-Pb zircon analysis of ignimbrites erupted from the adjacent Early Pleistocene La Reforma and El Aguajito calderas yielded ages of 1.38 ± 0.03 Ma ( n = 12; MSWD = 1.0) and 1.17 ± 0.07 Ma ( n = 23; MSWD = 1.3), respectively. No evidence for these ages is found among La Vírgen zircons, whereas pre-Quaternary zircon xenocrysts are common. The La Vírgen magma, therefore, evolved unrelated to Early Pleistocene magmatism in adjacent calderas, but assimilated local basement rocks. A gap between average Th-U and (U-Th)/He zircon ages suggests that zircon crystallization was discontinuous in the La Vírgen magma chamber. In addition, partial resorption of zircon suggests episodic thermal rejuvenation, most likely by basaltic recharge. Based on the zircon record, the > 100 ka lifetime of the thermal anomaly that sustained repeated intrusive pulses significantly exceeds the age of the last eruption. This strengthens the view that Tres

  6. Discriminating assimilants and decoupling deep- vs. shallow-level crystal records at Mount Adams using 238U-230Th disequilibria and Os isotopes

    Science.gov (United States)

    Jicha, B.R.; Johnson, C.M.; Hildreth, W.; Beard, B.L.; Hart, G.L.; Shirey, S.B.; Singer, B.S.

    2009-01-01

    A suite of 23 basaltic to dacitic lavas erupted over the last 350??kyr from the Mount Adams volcanic field has been analyzed for U-Th isotope compositions to evaluate the roles of mantle versus crustal components during magma genesis. All of the lavas have (230Th/238U) > 1 and span a large range in (230Th/232Th) ratios, and most basalts have higher (230Th/232Th) ratios than andesites and dacites. Several of the lavas contain antecrysts (crystals of pre-existing material), yet internal U-Th mineral isochrons from six of seven lavas are indistinguishable from their eruption ages. This indicates a relatively brief period of time between crystal growth and eruption for most of the phenocrysts (olivine, clinopyroxene, plagioclase, magnetite) prior to eruption. One isochron gave a crystallization age that is ~ 20-25??ka older than its corresponding eruptive age, and is interpreted to reflect mixing of older and juvenile crystals or a protracted period of magma storage in the crust. Much of the eruptive volume since 350??ka consists of lavas that have small to moderate 230Th excesses (2-16%), which are likely inherited from melting of a garnet-bearing intraplate ("OIB-like") mantle source. Following melt generation and subsequent migration through the upper mantle, most Mt. Adams magmas interacted with young, mafic lower crust, as indicated by 187Os/188Os ratios that are substantially more radiogenic than the mantle or those expected via mixing of subducted material and the mantle wedge. Moreover, Os-Th isotope variations suggest that unusually large 230Th excesses (25-48%) and high 187Os/188Os ratios in some peripheral lavas reflect assimilation of small degree partial melts of pre-Quaternary basement that had residual garnet or Al-rich clinopyroxene. Despite the isotopic evidence for lower crustal assimilation, these processes are not generally recorded in the erupted phenocrysts, indicating that the crystal record of the deep-level 'cryptic' processes has been

  7. Assessment of natural radionuclides concentration from {sup 238}U and {sup 232}Th series in Virginia and Burley varieties of Nicotiana tabacum L; Avaliacao da concentracao dos radionuclideos naturais das series do {sup 238}U e {sup 232}Th nas variedades Burley e Virginia da Nicotiana tabacum L.

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Carolina Fernanda da

    2015-07-01

    Brazil is the largest exporter and second largest producer of tobacco worldwide, according to the crop production of 2013/2014. The tobacco plant (Nicotiana tabacum L.) is used to manufacture all derivatives and the chemical composition of the resulting tobacco products varies with the type of tobacco leaves, how they are grown, the region where they are cultivated, the characteristics of preparation (compression, filter and paper) and the temperature variations resulting from the incomplete combustion of tobacco. Tobacco products are extensively used throughout the world, and the most consumed are cigarettes, cigars and narghile. The damaging effects that these products cause to human health are discussed globally, and many surveys are performed with the aim of relating the use of these products with various illnesses. There is a lack of information about the radiological characterization of the tobacco plant both in international and Brazilian literature. The objective of this study was to determine the concentration of radionuclides {sup 238}U, {sup 234}U, {sup 230}Th, {sup 22}'6Ra, {sup 210}Pb and {sup 210}Po, members from the {sup 238}U decay series, and the radionuclides {sup 232}Th and {sup 228}Ra members of the {sup 232}Th decay series in the varieties Burley and Virginia, which are the most cultivated in Brazil. Plants from these varieties were cultivated in pots with organic substrate and fertilizer and also acquired from the producers and analyzed by alpha spectrometry for U and Th isotopes and {sup 210}Po determination, and gross alpha and beta counting, {sup 228}Ra, {sup 226}Ra and {sup 210}Pb determination. The whole plant, from both places, was analyzed; root, stem, leaves, as well as the organic substrate, the fertilizers, and the soil. The results for U and Th isotopes presented values below the detection limits of the methods to the leaves and stems of all plants analyzed, with measurable results only in roots, soil, and substrate. The

  8. Investigation of uranium geochemistry along groundwater flow path in the Continental Intercalaire aquifer (Southern Tunisia).

    Science.gov (United States)

    Dhaoui, Z; Chkir, N; Zouari, K; Ammar, F Hadj; Agoune, A

    2016-06-01

    Environmental tracers ((2)H, (18)O, isotopes of Uranium) and geochemical processes occurring within groundwaters from the Continental Intercalaire (CI) in Southern Tunisia were used to understand the hydrodynamics and the recharge conditions of this aquifer. This study investigates the chemical and isotopic compositions of the CI groundwater. The water types are dominated by Na(+), SO4(2-), Cl(-) throughout most of the basin with a general increase in total dissolved solids from the Saharan Platform margins towards the Chotts region. Large scale groundwater flow paths are toward the Chotts region. The stable isotopes composition of the analyzed groundwater ranges from -8.8 to -6‰ vs V-SMOW for δ(18)O and from -67 to -40‰ vs V-SMOW for δ(2)H. The relatively enriched stable isotopes contents suggest the contribution of the Dahar sandstones outcrops in the current recharge of the CI aquifer in an arid context. However, the most depleted values in heavy isotopes indicate a paleorecharge of the aquifer under wetter conditions revealing a long residence time of groundwaters. The results from water samples using alpha spectrometry method indicate a range in (238)U concentrations and (234)U/(238)U activity ratios (AR) of 0.044-1.285 μg kg(-1) and 1.2 to 8.84 respectively. The geochemistry of uranium isotopes in groundwater is controlled by many factors, essentially, the influence of water rock interactions, the preferential dissolution of (234)U relative to (238)U due to alpha recoil and the mixing processes between different waters with distinct AR as well as (238)U concentrations.

  9. Standard test method for analysis of urine for uranium-235 and uranium-238 isotopes by inductively coupled plasma-mass spectrometry

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This test method covers the determination of the concentration of uranium-235 and uranium-238 in urine using Inductively Coupled Plasma-Mass Spectrometry. This test method can be used to support uranium facility bioassay programs. 1.2 This method detection limits for 235U and 238U are 6 ng/L. To meet the requirements of ANSI N13.30, the minimum detectable activity (MDA) of each radionuclide measured must be at least 0.1 pCi/L (0.0037 Bq/L). The MDA translates to 47 ng/L for 235U and 300 ng/L for 238U. Uranium– 234 cannot be determined at the MDA with this test method because of its low mass concentration level equivalent to 0.1 pCi/L. 1.3 The digestion and anion separation of urine may not be necessary when uranium concentrations of more than 100 ng/L are present. 1.4 Units—The values stated in picoCurie per liter units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. 1....

  10. Study on transfers of uranium, thorium and decay products from grain, water and soil to chicken meat and egg contents.

    Science.gov (United States)

    Jeambrun, M; Pourcelot, L; Mercat, C; Boulet, B; Loyen, J; Cagnat, X; Gauthier-Lafaye, F

    2012-08-01

    Activity concentrations of the uranium and thorium series radionuclides were determined in chicken meat and eggs as well as in soil, water and other dietary intakes of poultry at five sites of the French territory. These data allow the calculation of transfer coefficients which enrich the database given by the technical report series no. 472 of the IAEA. In egg contents, the highest activity concentrations (in mBq kg(-1) fresh weight) are for (226)Ra, ranging between 136 and 190 and are much lower for uranium (between 0.51 and 1.30 for (238)U). In chicken meat, (238)U activity concentration is higher than in egg contents and ranges between 1.7 and 9.7. Concerning (232)Th, its activity concentration is lower than uranium and ranges between 0.5 and 4.9. Daily ingested activity concentration by the animals was assessed taking into account the activity concentrations measured in the grains, in the soil and in the drinking water. The activity concentration in grains and the daily intakes allow the calculation of concentration ratios and transfer coefficients for chicken meat and egg contents. In chicken meat the transfer coefficients (d kg(-1)) range between 0.0018 and 0.0073 for (238)U and between 0.0008 and 0.0028 for (232)Th. In egg contents they range from 0.00018 to 0.0018 for (238)U and are much higher for radium isotopes (0.10-0.23 for (226)Ra and 0.07-0.11 for (228)Ra).

  11. 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.

  12. Geochemistry of natural radionuclide in soils surrounding a mining and plant uranium concentration;Geoquimica de radionuclindeos naturais em solos de areas circunvizinhas a uma unidade de mineracao e atividade de uranio

    Energy Technology Data Exchange (ETDEWEB)

    Cardoso, Gildevan Viana, E-mail: gildevan.cardoso@vta.incra.gov.b [Instituto Nacional de Colonizacao e Reforma Agraria (INCRA), Rio de Janeiro, RJ (Brazil); Amaral Sobrinho, Nelson Moura Brasil do; Mazur, Nelson, E-mail: nelmoura@ufrrj.b, E-mail: nelmazur@ufrrj.b [Universidade Federal Rural do Rio de Janeiro (UFRRJ), Seropedica, RJ (Brazil). Inst. de Agronomia. Dept. de Solos; Wasserman, Maria Angelica Vergara, E-mail: angelica@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2009-11-15

    The environmental impacts resulting from uranium exploration and processing are to a great extent identical to those caused by extractive mining activities in general. This study aimed to determine the geochemical partitioning of the natural radionuclides {sup 238}U, {sup 226}Ra and {sup 210}Pb in areas surrounding the Uranium Mining and Concentration Plant (URA) of the Brazilian Nuclear Industries S.A., in the uranium deposit region of Lagoa Real, in Caetite, southwestern Bahia state. Representative soil samples of the main regional soil classes were collected from the layer 0-20 cm, in five areas around the URA. The level of total activity and geochemical fractionation (F1 slightly acidic, F2 reducible, F3 oxidisable, F4 alkaline, and F5 residual) were determined for the five areas. The average total radioactivity levels were, in Bq kg{sup -1} soil: 50 for {sup 238}U, 51 for {sup 226}Ra, and 159 for {sup 210}Pb. During the potentially bioavailable phase (F1) 11 % were extracted for {sup 238}U, 13 % for {sup 226}Ra and 3 % for {sup 210}Pb. The bioavailability of {sup 238}U was higher in more acidic soils and the affinity for iron oxides was greater, unlike in the case of {sup 226}Ra, with the greatest bioavailability. {sup 210}Pb was predominantly associated with F5. The high percentage of {sup 238}U, {sup 226}Ra and {sup 210}Pb in the geochemical fraction F5 indicates that the concentrations observed in the five soils are predominantly associated to the parent material of these soils, rather than to an artificial contamination caused by the URA activity. (author)

  13. Dependency of renal thorium and uranium excretion from age and gender in non-exposed persons; Abhaengigkeit der renalen Thorium- und Uranausscheidung von Geschlecht und Alter bei nicht-exponierten Personen

    Energy Technology Data Exchange (ETDEWEB)

    Werner, E.; Roth, P.; Wendler, I.; Schramel, P. [GSF - Forschungszentrum fuer Umwelt und Gesundheit GmbH, Neuherberg (Germany)

    1998-12-31

    For the assessment of an occupational incorporation of thorium or uranium it is essential to know which portion of the measured activity is caused by natural sources. In the present study the daily urinary excretion of {sup 232}Th and {sup 238}U was measured in 76 healthy volunteers. None of them had a previous history of occupational exposure to thorium or uranium. The data show no difference in the excretion between male and female subjects. Whereas in adolescents only little excretion of {sup 232}Th and {sup 238}U is found, a significantly increasing variation of thorium and uranium in urine is observed with progressing age. From the data obtained an age-related upper limit of {sup 232}Th and {sup 238}U urinary excretion can be derived, which may be useful for the interpretation of a measured value due to the occupational exposure. (orig.) [Deutsch] Fuer die Beurteilung einer beruflich bedingten Inkorporation von Thorium oder Uran ist es wichtig zu wissen, welcher Artikel am gemessenen Wert auf natuerliche Quellen zurueckzufuehren ist. In der vorliegenden Studie wurde die taegliche Ausscheidung von{sup 232}Th und {sup 238}U im Urin bei 76 gesunden Personen im Alter von 7 bis 84 Jahren mit der ICP-MS gemessen. Keine dieser Personen hatte vorher beruflichen Umgang mit Thorium oder Uran gehabt. Die Daten zeigen keinen Unterschied zwischen Frauen und Maennern. Waehrend bei Jugendlichen nur geringe Ausscheidungswerte beobachtet werden, tritt mit zunehmendem Lebensalter eine erhebliche Vergroesserung des Variationsbereichs ein. Aus den erhobenen Daten ergibt sich eine altersbezogene Obergrenze fuer die {sup 232}Th- und {sup 238}U-Ausscheidung im Urin, die fuer die Interpretation eines Messwertes bei beruflicher Exposition herangezogen werden kann. (orig.)

  14. Uranium enrichment measurement task with a connectionist architecture

    Energy Technology Data Exchange (ETDEWEB)

    Vigneron, V.; Martinez, J.M. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. de Mecanique et de Technologie; Morel, J.; Lepy, M.C. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. des Applications et de la Metrologie des Rayonnements Ionisants

    1995-12-31

    Layered Neural Networks, which are a class of models based on neural computation, are applied to the measurement of uranium enrichment, i.e. the isotope ration {sup 235} U/({sup 235} U+{sup 236} U+{sup 238} U). The usual methods consider a limited number of {gamma}-ray and X-ray peaks, and requires previously calibrated instrumentation for each sample. But, in practice, the source-detector ensemble geometry conditions are critically different, thus a means of improving the above conventional methods is to reduce the region of interest: this is possible by focusing on the region called K{sub {alpha}}X where the three elementary components are present. The measurement of these components in mixtures leads to the desired ratio. Real data are used to study its performance. Training is done with a Maximum Likelihood method. We show the encoding of data by Neural Networks is a promising method to measure uranium {sup 235} U and {sup 238} U quantities in infinitely thick samples. (authors). 7 refs., 2 figs., 1 tab.

  15. Improved 206Pb/238U microprobe geochronology by the monitoring of a trace-element-related matrix effect; SHRIMP, ID-TIMS, ELA-ICP-MS and oxygen isotope documentation for a series of zircon standards

    Science.gov (United States)

    Black, L.P.; Kamo, S.L.; Allen, C.M.; Davis, D.W.; Aleinikoff, J.N.; Valley, J.W.; Mundil, R.; Campbell, I.H.; Korsch, R.J.; Williams, I.S.; Foudoulis, C.

    2004-01-01

    Precise isotope dilution-thermal ionisation mass spectrometry (ID-TIMS) documentation is given for two new Palaeozoic zircon standards (TEMORA 2 and R33). These data, in combination with results for previously documented standards (AS3, SL13, QGNG and TEMORA 1), provide the basis for a detailed investigation of inconsistencies in 206Pb/238U ages measured by microprobe. Although these ages are normally consistent between any two standards, their relative age offsets are often different from those established by ID-TIMS. This is true for both sensitive high-resolution ion-microprobe (SHRIMP) and excimer laser ablation-inductively coupled plasma-mass spectrometry (ELA-ICP-MS) dating, although the age offsets are in the opposite sense for the two techniques. Various factors have been investigated for possible correlations with age bias, in an attempt to resolve why the accuracy of the method is worse than the indicated precision. Crystallographic orientation, position on the grain-mount and oxygen isotopic composition are unrelated to the bias. There are, however, striking correlations between the 206Pb/238U age offsets and P, Sm and, most particularly, Nd abundances in the zircons. Although these are not believed to be the primary cause of this apparent matrix effect, they indicate that ionisation of 206Pb/238U is influenced, at least in part, by a combination of trace elements. Nd is sufficiently representative of the controlling trace elements that it provides a quantitative means of correcting for the microprobe age bias. This approach has the potential to reduce age biases associated with different techniques, different instrumentation and different standards within and between laboratories. Crown Copyright ?? 2004 Published by Elsevier B.V. All rights reserved.

  16. Determination of traces of uranium and thorium in titanium and copper used for the construction of the Russian Emission Detector 100 by inductively coupled plasma mass spectrometry.

    Science.gov (United States)

    Poteshin, Sergey S; Sysoev, Alexey A; Lagunov, Sergey S; Sereda, Andrei; Sosnovtsev, Valery V; Bolozdynya, Alexander I; Efremenko, Yuriy B

    2015-01-01

    The Russian Emission Detector 100 (RED-100) under construction at the National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) is designed to detect the presently undiscovered effect of coherent neutrino scattering. One of the factors limiting the sensitivity of the detector is the spontaneous decay of uranium and thorium in the detector materials. Radioactive impurities in detector materials at levels of parts per billion can significantly affect the sensitivity. Five random samples of titanium and one of copper from materials used in the construction of the detector were selected for assay. The concentration of (232)Th and (238)U were measured by inductively coupled plasma mass spectrometry (ICP- MS) in solid titanium using both: solutions in acids and direct sampling by laser ablation (LA-ICP-MS). The LA- ICP-MS method allowed us to determine (238)U and (232)Th at subnanogram per gram levels. This method is much faster than ICP-MS with liquid injection. The titanium samples studied have impurities in the range between 1 ng g(-1) and 21 ng g(-1) for (238)U and 3 ng g(-1) and 31 ng g(-1) for (232)Th. In copper we set upper limits of 0.4 ng g(-1) for (238)U and 1 ng g(-1)for (232)Th. The total activity of the cryostat constructed from materials studied was estimated to be 43 Bq.

  17. Measurement of neutron-induced fission cross-sections of Th232, U238, U233 and Np237 relative to U235 from 1 MeV to 200 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Shcherbakov, O.A.; Laptev, A.B.; Petrov, G.A. [Petersburg Nuclear Physics Inst., Gatchina, Leningrad district (Russian Federation); Fomichev, A.V.; Donets, A.Y.; Osetrov, O.I.

    1998-11-01

    The measurements of neutron-induced cross-section ratios for Th232, U238, U233 and Np237 relative to U235 have been carried out in the energy range from 1 MeV up to 200 MeV using the neutron time-of-flight spectrometer GNEIS based on 1 GeV proton synchrocyclotron. Below 20 MeV, the results of present measurements are roughly in agreement with evaluated data though there are some discrepances to be resolved. (author)

  18. Uncertainty analyses in the resolved resonance region of {sup 235}U, {sup 238}U, and {sup 239}Pu with the Reich-Moore R-matrix theory for JENDL-3.2

    Energy Technology Data Exchange (ETDEWEB)

    Kawano, Toshihiko [Kyushu University, Interdisciplinary Graduate School of Engineering Sciences, Kasuga, Fukuoka (Japan); Shibata, Keiichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2002-08-01

    A simple method to estimate covariances for resolved resonance parameters was developed. Although a large number of resolved resonances are observed for major actinides, uncertainties in averaged cross sections are more important than those in resonance parameters in reactor calculations. The method developed here derives a covariance matrix for the resolved resonance parameters which gives an appropriate uncertainty of the averaged cross sections. The method was adopted to evaluate the covariance data for {sup 235}U, {sup 238}U, and {sup 239}Pu resonance parameters in JENDL-3.2, with the Reich-Moore R-matrix formula. (author)

  19. Nucleogenic {sup 36}Cl, {sup 236}U and {sup 239}Pu in uranium ores

    Energy Technology Data Exchange (ETDEWEB)

    Wilcken, K.M. [Department of Nuclear Physics, RSPhysSE, Australian National University, Canberra, ACT 0200 (Australia); Scottish Universities Environmental Research Centre, Scottish Enterprise Technology Park, Rankine Avenue, East Kilbride G75 0QF (United Kingdom)], E-mail: K.Wilcken@suerc.gla.ac.uk; Fifield, L.K.; Barrows, T.T.; Tims, S.G.; Gladkis, L.G. [Department of Nuclear Physics, RSPhysSE, Australian National University, Canberra, ACT 0200 (Australia)

    2008-08-15

    The nucleogenic isotopes {sup 36}Cl, {sup 236}U and {sup 239}Pu are produced naturally in subsurface environments via neutron capture of thermal and epithermal neutrons. Concentrations are, however, very low and accelerator mass spectrometry (AMS) is required for quantitative measurements. A particular challenge is presented by the measurement of {sup 236}U/{sup 238}U ratios down to the level of 10{sup -13} that is expected from rocks with low uranium concentration. Here, we present the AMS methodology that has been developed at the ANU for measuring {sup 236}U/{sup 238}U ratios at this level. The more established methodologies for {sup 36}Cl and {sup 239}Pu measurements are also summarised. These capabilities are then used to characterize the {sup 36}Cl, {sup 236}U and {sup 239}Pu concentrations in a range of uranium ores. A simple model of the neutron production and capture processes in subsurface environments has been developed and is presented. It is shown that nucleogenic {sup 36}Cl, {sup 236}U and {sup 239}Pu can be used to determine both thermal and epithermal neutron fluxes in subsurface environments. Potential applications include uranium exploration and monitoring of the environmental impact of uranium mining.

  20. Nucleogenic 36Cl, 236U and 239Pu in uranium ores

    Science.gov (United States)

    Wilcken, K. M.; Fifield, L. K.; Barrows, T. T.; Tims, S. G.; Gladkis, L. G.

    2008-08-01

    The nucleogenic isotopes 36Cl, 236U and 239Pu are produced naturally in subsurface environments via neutron capture of thermal and epithermal neutrons. Concentrations are, however, very low and accelerator mass spectrometry (AMS) is required for quantitative measurements. A particular challenge is presented by the measurement of 236U/ 238U ratios down to the level of 10 -13 that is expected from rocks with low uranium concentration. Here, we present the AMS methodology that has been developed at the ANU for measuring 236U/ 238U ratios at this level. The more established methodologies for 36Cl and 239Pu measurements are also summarised. These capabilities are then used to characterize the 36Cl, 236U and 239Pu concentrations in a range of uranium ores. A simple model of the neutron production and capture processes in subsurface environments has been developed and is presented. It is shown that nucleogenic 36Cl, 236U and 239Pu can be used to determine both thermal and epithermal neutron fluxes in subsurface environments. Potential applications include uranium exploration and monitoring of the environmental impact of uranium mining.

  1. Measurement system analysis (MSA) of the isotopic ratio for uranium isotope enrichment process control

    Energy Technology Data Exchange (ETDEWEB)

    Medeiros, Josue C. de; Barbosa, Rodrigo A.; Carnaval, Joao Paulo R., E-mail: josue@inb.gov.br, E-mail: rodrigobarbosa@inb.gov.br, E-mail: joaocarnaval@inb.gov.br [Industrias Nucleares do Brasil (INB), Rezende, RJ (Brazil)

    2013-07-01

    Currently, one of the stages in nuclear fuel cycle development is the process of uranium isotope enrichment, which will provide the amount of low enriched uranium for the nuclear fuel production to supply 100% Angra 1 and 20% Angra 2 demands. Determination of isotopic ration n({sup 235}U)/n({sup 238}U) in uranium hexafluoride (UF{sub 6} - used as process gas) is essential in order to control of enrichment process of isotopic separation by gaseous centrifugation cascades. The uranium hexafluoride process is performed by gas continuous feeding in separation unit which uses the centrifuge force principle, establishing a density gradient in a gas containing components of different molecular weights. The elemental separation effect occurs in a single ultracentrifuge that results in a partial separation of the feed in two fractions: an enriched on (product) and another depleted (waste) in the desired isotope ({sup 235}UF{sub 6}). Industrias Nucleares do Brasil (INB) has used quadrupole mass spectrometry (QMS) by electron impact (EI) to perform isotopic ratio n({sup 235}U)/n({sup 238}U) analysis in the process. The decision of adjustments and change te input variables are based on the results presented in these analysis. A study of stability, bias and linearity determination has been performed in order to evaluate the applied method, variations and systematic errors in the measurement system. The software used to analyze the techniques above was the Minitab 15. (author)

  2. Predicting equilibrium uranium isotope fractionation in crystals and solution

    Science.gov (United States)

    Schauble, E. A.

    2015-12-01

    Despite the rapidly growing interest in using 238U/235U measurements as a proxy for changes in oxygen abundance in surface and near-surface environments, the present theoretical understanding of uranium isotope fractionation is limited to a few simple gas-phase molecules and analogues of dissolved species (e.g., 1,2,3). Understanding uranium isotope fractionation behavior in more complicated species, such as crystals and adsorption complexes, will help in the design and interpretation of experiments and field studies, and may suggest other uses for 38U/235U measurements. In this study, a recently developed first-principles method for estimating the nuclear volume component of field shift fractionation in crystals and complex molecular species (4) is combined with mass-dependent fractionation theory to predict equilibrium 38U/235U fractionations in aqueous and crystalline uranium compounds, including uraninite (UO2). The nuclear field shift effect, caused by the interaction of electrons with the finite volume of the positive charge distribution in uranium nuclei, is estimated using Density Functional Theory and the Projector Augmented Wave method (DFT-PAW). Tests against relativistic electronic structure calculations and Mössbauer isomer shift data indicate that the DFT-PAW method is reasonably accurate, while being much better suited to models of complex and crystalline species. Initial results confirm previous predictions that the nuclear volume effect overwhelms mass depdendent fractionation in U(VI)-U(IV) exchange reactions, leading to higher 238U/235U in U(IV) species (i.e., for UO2 xtal vs. UO22+aq, ln αNV ≈ +1.8‰ , ln αMD ≈ -0.8‰, ln αTotal ≈ +1.0‰ at 25ºC). UO2 and U(H2O)94+, are within ~0.4‰ of each other, while U(VI) species appear to be more variable. This suggests that speciation is likely to significantly affect natural uranium isotope fractionations, in addition to oxidation state. Tentatively, it appears that uranyl-type (UO22

  3. Field Measurement of Am241 and Total Uranium at a Mixed Oxide Fuel Facility with Variable Uranium Enrichments Ranging from 0.3% to 97% U235

    Energy Technology Data Exchange (ETDEWEB)

    Conway, K. C.

    2002-02-28

    The uranium and transuranic content of site soils and building rubble can be accurately measured using a NaI(Tl) well counter, without significant soil preparation. Accurate measurements of total uranium in uranium-transuranic mixtures can be made, despite a wide range (0.3% to 97%) of uranium enrichment, sample mass, and activity concentrations. The appropriate uranium scaling factors needed to include the undetected uranium isotopes, particularly U 234 can be readily determined on a sample by sample basis as a part of the field analysis, by comparing the relative response of the U 235 186 keV peak versus the K shell X rays of U 238 , U 235, and their immediate ingrowth daughters. The ratio of the two results is a sensitive and accurate predictor of the uranium enrichment and scaling factors. The case study will illustrate how NaI(Tl) gamma spectrometry was used to provide rapid turnaround uranium and transuranic activity levels for soil and building rubble with sample by sample determination of the appropriate scaling factor to include the U234 and Uranium238 content.

  4. Determination of relative krypton fission product yields from 14 MeV neutron induced fission of 238U at the National Ignition Facility

    Science.gov (United States)

    Edwards, E. R.; Cassata, W. S.; Velsko, C. A.; Yeamans, C. B.; Shaughnessy, D. A.

    2016-11-01

    Precisely-known fission yield distributions are needed to determine a fissioning isotope and the incident neutron energy in nuclear security applications. 14 MeV neutrons from DT fusion at the National Ignition Facility induce fission in depleted uranium contained in the target assembly hohlraum. The fission yields of Kr isotopes (85m, 87, 88, and 89) are measured relative to the cumulative yield of 88Kr and compared to previously tabulated values. The results from this experiment and England and Rider are in agreement, except for the 85mKr/88Kr ratio, which may be the result of incorrect nuclear data.

  5. 235U, 238U, 232Th, 40K and 137Cs activity concentrations in marine sediments along the northern coast of Oman Sea using high-resolution gamma-ray spectrometry.

    Science.gov (United States)

    Zare, Mohammad Reza; Mostajaboddavati, Mojtaba; Kamali, Mahdi; Abdi, Mohammad Reza; Mortazavi, Mohammad Seddigh

    2012-09-01

    The natural radioactivity levels in sediment samples of the northern coast of Oman Sea, covering the coastal strip from Hormoz canyon to Goatr seaport, as the first time has been determined. The results of measurements will serve as background reference level for Oman Sea coastlines. Sediments from 36 coastal and near shore locations were collected for analysis. Analysis on the collected samples were carried out to determine (235)U, (238)U, (232)Th, (40)K and (137)Cs using two high purity germanium detectors with 38.5% and 55% relative efficiencies. The concentration of (235)U, (238)U, (232)Th, (40)K and (137)Cs in sediment samples ranged between 1.01 and 2.87 Bq/kg, 11.83 and 22.68 Bq/kg, 10.7 and 25.02 Bq/kg, 222.89 and 535.07 Bq/kg and 0.14 and 2.8 Bq/kg, respectively. The radium equivalent activity was well below the defined limit of 370 Bq/kg. The external hazard indices were found to be less than 1, indicating a low dose.

  6. Neutron capture cross section measurement of 238U at the n TOF CERN facility with C6D6 scintillation detectors in the energy region from 1 eV to 700 keV

    CERN Document Server

    Mingrone, F.; Vannini, G.; Colonna, N.; Gunsing, F.; Žugec, P.; Altstadt, S.; Andrzejewski, J.; Audouin, L.; Barbagallo, M.; Bécares, V.; Bečvář, F.; Belloni, F.; Berthoumieux, E.; Billowes, J.; Bosnar, D.; Brugger, M.; Calviani, M.; Calviño, F.; Cano-Ott, D.; Carrapiço, C.; Cerutti, F.; Chiaveri, E.; Chin, M.; Cortés, G.; Cortés-Giraldo, M.A.; Diakaki, M.; Domingo-Pardo, C.; Duran, I.; Dressler, R.; Eleftheriadis, C.; Ferrari, A.; Fraval, K.; Ganesan, S.; García, A.R.; Giubrone, G.; Gonçalves, I.F.; González-Romero, E.; Griesmayer, E.; Guerrero, C.; Hernández-Prieto, A.; Jenkins, D.G.; Jericha, E.; Kadi, Y.; Käppeler, F.; Karadimos, D.; Kivel, N.; Koehler, P.; Kokkoris, M.; Krtička, M.; Kroll, J.; Lampoudis, C.; Langer, C.; Leal-Cidoncha, E.; Lederer, C.; Leeb, H.; Leong, L.S.; Lo Meo, S.; Losito, R.; Mallick, A.; Manousos, A.; Marganiec, J.; Martínez, T.; Mastinu, P.F.; Mastromarco, M.; Mendoza, E.; Mengoni, A.; Milazzo, P.M.; Mirea, M.; Mondalaers, W.; Paradela, C.; Pavlik, A.; Perkowski, J.; Plompen, A.; Praena, J.; Quesada, J.M.; Rauscher, T.; Reifarth, R.; Riego, A.; Robles, M.S.; Rubbia, C.; Sabaté-Gilarte, M.; Sarmento, R.; Saxena, A.; Schillebeeckx, P.; Schmidt, S.; Schumann, D.; Tagliente, G.; Tain, J.L.; Tarrío, D.; Tassan-Got, L.; Tsinganis, A.; Valenta, S.; Variale, V.; Vaz, P.; Ventura, A.; Vermeulen, M.J.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Ware, T.; Weigand, M.; Weiß, C.; Wright, T.

    2016-01-01

    The aim of this work is to provide a precise and accurate measurement of the 238U(n,g) reaction cross section in the energy region from 1 eV to 700 keV. This reaction is of fundamental importance for the design calculations of nuclear reactors, governing the behaviour of the reactor core. In particular, fast reactors, which are experiencing a growing interest for their ability to burn radioactive waste, operate in the high energy region of the neutron spectrum. In this energy region most recent evaluations disagree due to inconsistencies in the existing measurements of up to 15%. In addition, the assessment of nuclear data uncertainty performed for innovative reactor systems shows that the uncertainty in the radiative capture cross-section of 238U should be further reduced to 1-3% in the energy region from 20 eV to 25 keV. To this purpose, addressed by the Nuclear Energy Agency as a priority nuclear data need, complementary experiments, one at the GELINA and two at the n_TOF facility, were proposed and carrie...

  7. Neutron capture cross section measurement of $^{238}$U at the n_TOF CERN facility in the energy region from 1 eV to 700 keV

    CERN Document Server

    Mingrone, F; Vannini, G; Colonna, N; Gunsing, F; Zugec, P; Altstadt, S; Andrzejewski, J; Audouin, L; Barbagallo, M; Becares, V; Becvavr, F; Belloni, F; Berthoumieux, E; Billowes, J; Bosnar, D; Brugger, M; Calviani, M; Calvino, F; Cano-Ott, D; Carrapico, C; Cerutti, F; Chiaveri, E; Chin, M; Cortes, G; Cortes-Giraldo, M A; Diakaki, M; Domingo-Pardo, C; Duran, I; Dressler, R; Eleftheriadis, C; Ferrari, A; Fraval, K; Ganesan, S; Garcia, A R; Giubrone, G; Goncalves, I F; Gonzalez-Romero, E; Griesmayer, E; Guerrero, C; Hernandez-Prieto, A; Jenkins, D G; Jericha, E; Kadi, Y; Kappeler, F; Karadimos, D; Kivel, N; Koehler, P; Kokkoris, M; Krticka, M; Kroll, J; Lampoudis, C; Langer, C; Leal-Cidoncha, E; Lederer, C; Leeb, H; Leong, L S; Lo Meo, S; Losito, R; Mallick, A; Manousos, A; Marganiec, J; Martinez, T; Mastinu, P F; Mastromarco, M; Mendoza, E; Mengoni, A; Milazzo, P M; Mirea Horia, M; Mondalaers, W; Paradela, C; Pavlik, A; Perkowski, J; Plompen, A; Praena, J; Quesada, J M; Rauscher, T; Reifarth, R; Riego, A; Robles, M S; Rubbia, C; Sabate-Gilarte, M; Sarmento, R; Saxena, A; Schillebeeckx, P; Schmidt, S; Schumann, D; Tagliente, G; LTain, J; Tarrio, D; Tassan-Got, L; Tsinganis, A; Valenta, S; Variale, V; Vaz, P; Ventura, A; Vermeulen, M J; Vlachoudis, V; Vlastou, R; Wallner, A; Ware, T; Weigand, M; Weiss, C; Wright, T

    2016-01-01

    The aim of this work is to provide a precise and accurate measurement of the $^{238}$U(n,$\\gamma$) reaction cross section in the energy region from 1 eV to 700 keV. This reaction is of fundamental importance for the design calculations of nuclear reactors, governing the behaviour of the reactor core. In particular, fast reactors, which are experiencing a growing interest for their ability to burn radioactive waste, operate in the high energy region of the neutron spectrum. In this energy region most recent evaluations disagree due to inconsistencies in the existing measurements of up to 15%. In addition, the assessment of nuclear data uncertainty performed for innovative reactor systems shows that the uncertainty in the radiative capture cross-section of $^{238}$U should be further reduced to 1-3% in the energy region from 20 eV to 25 keV. To this purpose, addressed by the Nuclear Energy Agency as a priority nuclear data need, complementary experiments, one at the GELINA and two at the n_TOF facility, were pr...

  8. 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

  9. Uranium and plutonium in anoxic marine sediments of the Santiago River mouth (Eastern Pacific, Mexico).

    Science.gov (United States)

    Almazán-Torres, María Guadalupe; Ordóñez-Regil, Eduardo; Ruiz-Fernández, Ana Carolina

    2016-11-01

    The uranium (U) and plutonium (Pu) content with depth in a sediment core collected in the continental shelf off the mouth of the Santiago River in the Mexican Pacific was studied to evaluate the contamination effects of the effluent of the Santiago-Lerma River as it moves into the sea. The large mass of terrestrial detritus delivered by the river influences the physicochemical and geochemical processes in the seafloor. Abnormal concentrations of U and Pu in sediments were examined as indicative of the effects of anoxic conditions. One of the indicators of pollution of seawater is the bacterial activity of the shallow seabed layer; and among the prevailing bacteria, the magnetotactic ones induce the formation of euhedral and framboidal shapes (pyrite). These pyrite entities are by-products of anoxic environments loaded with decomposing detrital material and are very abundant in the surface layers of the sediment core analyzed. The pyrite formation is the result of a biochemical reaction between iron and organic sulphur reduced by bacteria, and the pyrite entities precipitate to the seafloor. In the same upper zone of the profile, (238)U is readily immobilized, while (234)U is oxidized and dissolved in seawater by the effect of hot atom chemistry. This may cause the activity ratio (AR) (234)U/(238)U disequilibrium (near 0.41). Furthermore, in the shallow layer of the sediment core, an abnormally high concentration of (239+240)Pu was detected. In this upper layer, the activity concentrations found were 3.19 Bq kg(-1) for (238)U, 1.32 kg(-1) for (234)U and 2.78 Bq kg(-1) for (239+240)Pu. In the lower fractions of the sediment core, normal values of AR (234)U/(238)U (≈1) were found, with traces of (239+240)Pu.

  10. Influence of soil parameters on the linearity of the soil-to-plant transfer process of {sup 238}U and {sup 226}Ra

    Energy Technology Data Exchange (ETDEWEB)

    Blanco Rodriguez, P.; Vera Tome, F. [Natural Radioactivity Group. Universidad de Extremadura, 06071 Badajoz (Spain); Lozano, J.C. [Laboratorio de Radiactividad Ambiental. Universidad de Salamanca, 37008 Salamanca (Spain)

    2014-07-01

    Transfer from soil to plant is an important input of radionuclides into the food chain. Also, the mobility of radionuclides in soils is enhanced through their passage into the plant compartment. Thus, the soil-to-plant transfer of radionuclides raises the potential human dose. In radiological risk assessment models, this process is usually considered to be an equilibrium process such that the activity concentration in plants is linearly related to the soil concentration through a constant transfer factor (TF). However, the large variability present by measured TF values leads to major uncertainties in the assessment of risks. One possible way to reduce this variability in TF values is to parametrize their determination. This paper presents correlations of TF with the major element concentrations in soils. The findings confirm the major influence of the chemical environment of a soil on the assimilation process. The variability of TF might be greatly reduced if only the labile fraction were considered. Experiments performed with plants (Helianthus annuus L.) growing in a hydroponic medium appear to confirm this suggestion, showing a linear correlation between the plant and the soil solution activity concentrations. Extracting the labile fraction of a real soil is no trivial task, however. A possible operationally definable method is to consider the water-soluble together with the exchangeable fractions of the soil. Studies performed in granitic soils showed that the labile concentration of uranium and radium strongly depended on the soil's textural characteristics. In this sense, a parametrization is proposed of the labile uranium and radium concentration as a function of the soil's granulometric parameters. (authors)

  11. Elemental bio-imaging of thorium, uranium, and plutonium in tissues from occupationally exposed former nuclear workers.

    Science.gov (United States)

    Hare, Dominic; Tolmachev, Sergei; James, Anthony; Bishop, David; Austin, Christine; Fryer, Fred; Doble, Philip

    2010-04-15

    Internal exposure from naturally occurring radionuclides (including the inhaled long-lived actinides (232)Th and (238)U) is a component of the ubiquitous background radiation dose (National Council on Radiation Protection and Measurements. Ionizing radiation exposure of the population of the United States; NCRP Report No. 160; NCRP: Bethesda, MD, 2009). It is of interest to compare the concentration distribution of these natural alpha-emitters in the lungs and respiratory lymph nodes with those resulting from occupational exposure, including exposure to anthropogenic plutonium and depleted and enriched uranium. This study examines the application of laser ablation-inductively coupled plasma-mass spectrometry (LA-ICPMS) to quantifying and visualizing the mass distribution of uranium and thorium isotopes from both occupational and natural background exposure in human respiratory tissues and, for the first time, extends this application to the direct imaging of plutonium isotopes. Sections of lymphatic and lung tissues taken from deceased former nuclear workers with a known history of occupational exposure to specific actinide elements (uranium, plutonium, or americium) were analyzed by LA-ICPMS. Using a previously developed LA-ICPMS protocol for elemental bio-imaging of trace elements in human tissue and a new software tool, we generated images of thorium ((232)Th), uranium ((235)U and (238)U), and plutonium ((239)Pu and (240)Pu) mass distributions in sections of tissue. We used a laboratory-produced matrix-matched standard to quantify the (232)Th, (235)U, and (238)U concentrations. The plutonium isotopes (239)Pu and (240)Pu were detected by LA-ICPMS in 65 mum diameter localized regions of both a paratracheal lymph node and a sample of lung tissue from a person who was occupationally exposed to refractory plutonium (plutonium dioxide). The average (overall) (239)Pu concentration in the lymph node was 39.2 ng/g, measured by high purity germanium (HPGe) gamma

  12. Dating by fission track method: study of neutron dosimetry with natural uranium thin films; Datacao com o metodo dos tracos de fissao: estudo da dosimetria de neutrons com filmes finos de uranio natural

    Energy Technology Data Exchange (ETDEWEB)

    Iunes, P.J.

    1990-06-01

    Fission track dating is described, focalizing the problem of the decay constant for spontaneous fission of {sup 238} U and the use of neutron dosimetry in fission track analysis. Experimental procedures using thin films of natural uranium as neutron dosimeters and its results are presented. The author shows a intercomparison between different thin films and between the dosimetry with thin film and other dosimetries. (M.V.M.). 52 refs, 12 figs, 9 tabs.

  13. Uranium mill ore dust characterization

    Energy Technology Data Exchange (ETDEWEB)

    Knuth, R.H.; George, A.C.

    1980-11-01

    Cascade impactor and general air ore dust measurements were taken in a uranium processing mill in order to characterize the airborne activity, the degree of equilibrium, the particle size distribution and the respirable fraction for the /sup 238/U chain nuclides. The sampling locations were selected to limit the possibility of cross contamination by airborne dusts originating in different process areas of the mill. The reliability of the modified impactor and measurement techniques was ascertained by duplicate sampling. The results reveal no significant deviation from secular equilibrium in both airborne and bulk ore samples for the /sup 234/U and /sup 230/Th nuclides. In total airborne dust measurements, the /sup 226/Ra and /sup 210/Pb nuclides were found to be depleted by 20 and 25%, respectively. Bulk ore samples showed depletions of 10% for the /sup 226/Ra and /sup 210/Pb nuclides. Impactor samples show disequilibrium of /sup 226/Ra as high as +-50% for different size fractions. In these samples the /sup 226/Ra ratio was generally found to increase as particle size decreased. Activity median aerodynamic diameters of the airborne dusts ranged from 5 to 30 ..mu..m with a median diameter of 11 ..mu..m. The maximum respirable fraction for the ore dusts, based on the proposed International Commission on Radiological Protection's (ICRP) definition of pulmonary deposition, was < 15% of the total airborne concentration. Ore dust parameters calculated for impactor duplicate samples were found to be in excellent agreement.

  14. Evidence of isotopic fractionation of natural uranium in cultured human cells

    Science.gov (United States)

    Paredes, Eduardo; Avazeri, Emilie; Malard, Véronique; Vidaud, Claude; Reiller, Pascal E.; Ortega, Richard; Nonell, Anthony; Isnard, Hélène; Chartier, Frédéric; Bresson, Carole

    2016-12-01

    The study of the isotopic fractionation of endogen elements and toxic heavy metals in living organisms for biomedical applications, and for metabolic and toxicological studies, is a cutting-edge research topic. This paper shows that human neuroblastoma cells incorporated small amounts of uranium (U) after exposure to 10 µM natural U, with preferential uptake of the 235U isotope with regard to 238U. Efforts were made to develop and then validate a procedure for highly accurate n(238U)/n(235U) determinations in microsamples of cells. We found that intracellular U is enriched in 235U by 0.38 ± 0.13‰ (2σ, n = 7) relative to the exposure solutions. These in vitro experiments provide clues for the identification of biological processes responsible for uranium isotopic fractionation and link them to potential U incorporation pathways into neuronal cells. Suggested incorporation processes are a kinetically controlled process, such as facilitated transmembrane diffusion, and the uptake through a high-affinity uranium transport protein involving the modification of the uranyl (UO22+) coordination sphere. These findings open perspectives on the use of isotopic fractionation of metals in cellular models, offering a probe to track uptake/transport pathways and to help decipher associated cellular metabolic processes.

  15. Solid-phase data from cores at the proposed Dewey Burdock uranium in-situ recovery mine, near Edgemont, South Dakota

    Science.gov (United States)

    Johnson, Raymond H.; Diehl, Sharon F.; Benzel, William M.

    2013-01-01

    This report releases solid-phase data from cores at the proposed Dewey Burdock uranium in-situ recovery site near Edgemont, South Dakota. These cores were collected by Powertech Uranium Corporation, and material not used for their analyses were given to the U.S. Geological Survey for additional sampling and analyses. These additional analyses included total carbon and sulfur, whole rock acid digestion for major and trace elements, 234U/238U activity ratios, X-ray diffraction, thin sections, scanning electron microscopy analyses, and cathodoluminescence. This report provides the methods and data results from these analyses along with a short summary of observations.

  16. The effect of uranium migration on radionuclide distributions for soil samples at the El-Gor area, Sinai, Egypt.

    Science.gov (United States)

    Nada, A; Aly, H A S

    2014-02-01

    The concentrations and distributions of the activity of natural radionuclides in soil samples were investigated in fifteen soil samples at El-Gor area representing two profiles (A and B) using a HP-Ge detector and alpha counting by SSNTD (CR-39), respectively. The average concentrations of the radionuclides (238)U, (226)Ra, (235)U, (232)Th and (40)K are 203.4, 177.23, 9.77, 43.33 and 386.22 Bq kg(-1) (dry weight), respectively, and profile A and (238)U, (226)Ra, (235)U, (232)Th and (40)K have average concentrations of 232.58, 246, 11.7, 31.7, and 277.07 Bq kg(-1) for profile B, respectively. The eTh and eU were estimated to detect the migration process of uranium into or out of an area or uranium to or from the studied profiles. The results indicate a migration of uranium by 29% for profile A and 65.37% for profile B. The activity ratio ((238)U/(226)Ra) was found to be 0.9 in profile A and 1.15 in profile B. These ratios coincide with the uranium migration processes. The responsible mass corresponding to the measured (226)Ra activity was also calculated. The radon activity concentrations for the two profiles are nearly 300 Bq m(-3). The emanation coefficient (η) was calculated from the ratio of the expected radon activity to the measured radon for the studied soil samples. The value of η was found to depend only on the radium activity regardless to soil formation.

  17. Derivation and implementation of an annual limit on intake and a derived air concentration value for uranium mill tailings.

    Science.gov (United States)

    Reif, R H; Andrews, D W

    1995-06-01

    Monitoring workers and work areas at the Department of Energy Uranium Mill Tailings Remedial Action Project sites is complex because all radionuclides in the 238U and 235U decay chains may be present in an airborne uranium mill tailings matrix. Previous monitoring practices involved isotopic analysis of the air filter to determine the activity of each radionuclide of concern and comparing the results to the specified derived air concentration. The annual limit on intake and derived air concentration values have been derived here for the uranium mill tailings matrix to simplify the procedure for evaluation of air monitoring results and assessment of the need for individual monitoring. Implementation of the derived air concentration for uranium mill tailings involves analyzing air samples for long-lived gross alpha activity and comparing the activity concentration to the derived air concentration. Health physics decisions regarding assessment of airborne concentrations is more cost-effective because isotopic analysis of air samples is not necessary.

  18. Uranium isotopes determination in urine samples using alpha spectrometry and ICP-MS

    Energy Technology Data Exchange (ETDEWEB)

    Rosa, Mychelle M.L.; Maihara, Vera A. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Tine, Fernanda D.; Santos, Sandra M.C.; Bonifacio, Rodrigo L.; Taddei, Maria HelenaT. [Comissao Nacional de Energia Nuclear (LAPOC/CNEN-MG), Pocos de Caldas, MG (Brazil). Laboratorio de Pocos de Caldas

    2015-07-01

    The action of determining the concentration of uranium isotopes in biological samples, 'in vitro' bioassay, is an indirect method for evaluating the incorporation and quantification of these radionuclides internally deposited. When incorporated, these radionuclides tend to be disposed through excretion, with urine being the main source of data because it can be easily collected and analyzed. The most widely used methods for determination of uranium isotopes ({sup 234}U, {sup 235}U and {sup 238}U) are Alpha Spectrometry and ICP-MS. This work presents a comparative study for the determination of uranium isotopes using these two methodologies in real samples from occupationally exposed workers. In order to validate the methodology, a sample of the intercomparison exercise organized by PROCORAD (Association pour la Promotion du Controle de Qualite des Analyses de Biologie Medicale em Radiotoxicologie) was used, and the results were statistically compared applying the Student's t-test. (author)

  19. Contamination by depleted uranium (Du) in South Serbia

    Energy Technology Data Exchange (ETDEWEB)

    Popovic, L. [Faculty of Veterinary Medicine, Dept. of Physics and Biophysics, Belgrade, Serbia and Montenegro (Serbia); Todorovic, J. [Environmental And Radiation Protection Laboratory, Institute Of Nuclear Sciences Vinca, Belgrade, Serbia and Montenegro (Serbia); Bozic, P.; Stevanovic, Z. [Faculty of Veterinary Medicine, Belgrade, Dept. Of Pathology And Biochemistry, Serbia and Montenegro (Serbia)

    2006-07-01

    The paper present the results of the study on D.U. (depleted uranium) contamination in the environment and possible effects on animal healths in the region o f Bujanovac. Samples of soil, feed, leaves, grass, lichen, moss, honey and water were collected randomly in 2003/2004 in the vicinity of the target area (500-1000 m) and 5 km from the target area. Activity of the radionuclides ({sup 226}Ra, {sup 232}Th, {sup 40}K, {sup 210}Pb, {sup 238}U, {sup 235}U, {sup 137}Cs, {sup 7}Be) in soils, grass, lichen, moss and honey was determined on Hp Ge detector (Canberra, relative efficiency 23%) by standard gamma spectrometry. Total alpha and beta activity in water was determined on proportional alpha/beta counter (Canberra 2400, efficiency for alpha emitters 11%, efficiency for beta emitters 30%). Non significantly higher values of concentrations of {sup 226}Ra, {sup 232}Th, {sup 238}U and {sup 235}U were measured in the immediate vicinity of the targeted site, but {sup 235}U/{sup 238}U activity ratio in soils indicated the natural origin of uranium. On both sites the contents of radionuclides in soils were in the range of values measured in soils in Belgrade (2002-2005), at the mountain Stara Planina (1999) and in the region. The soil was found to be poor in potassium. In mosses and lichen, high concentrations of {sup 137}Cs, {sup 7}Be, {sup 226}Ra and {sup 210}Pb were found, while in leaves and grass there were lower concentrations of K, due to soil poor in K. As for uranium, there were no significant variations due to the sites, and {sup 235}U/{sup 238}U activity ratios were close to values measured in vegetation in the vicinity of power plants 0.07-0.08. In honey, both {sup 238}U and {sup 235}U were below the minimal detectable concentrations. Total alpha and total beta activities measured in water showed no significant differences between the sites, and the obtained values were in range of the permissible values for drinking water in S.M.N. (total alpha activity <0

  20. Sorption behavior of U(VI), 234U(VI) and 238U(VI) onto fracture-filling clays in Beishan granite, Gansu: Application to selecting the site of high-level radwaste repository in China

    Institute of Scientific and Technical Information of China (English)

    MIN; Maozhong; LUO; Xingzhang; WANG; Ju; JIN; Yuanxin; WAN

    2005-01-01

    The first results of sorption experiments of U(VI), 234U(VI) and 238U(VI) onto original (unpurified) fracture-filling clays from No.1 monzonitic granite intrusion, Beishan area, Gansu Province, China are reported. The monzonitic granite intrusion is a potential location for a high-level radwaste (HLW) repository in China. The present experimental results show that the maximum U(VI) sorption reached 92% at near-neutral Ph and the distribution coefficient (Kd) was 1226 Ml/g. A high sorption capacity of the fracture-filling clays in host rock on radioactive elements is necessary for HLW deep geological disposal repository. No preferential sorption of 234U onto the clays was found. Finally, the sorption of U(VI) onto the clays was also modeled using a surface complexation model.

  1. Spin-alignment and g-factor measurement of the I{sup {pi}}=12{sup +} isomer in {sup 192}Pb produced in the relativistic-energy fragmentation of a {sup 238}U beam

    Energy Technology Data Exchange (ETDEWEB)

    Kmiecik, M.; Maj, A.; Ciemala, M.; Grebosz, J.; Lach, M.; Maier, K.H.; Mazurek, K.; Meczynski, W.; Myalski, S.; Styczen, J.; Zieblinski, M. [H. Niewodniczanski Inst. of Nuclear Physics PAN, Krakow (Poland); Gerl, J.; Becker, F.; Caceres, L.; Doornenbal, P.; Gorska, M.; Grawe, H.; Kojuharov, I.; Prokopowicz, W.; Saito, N.; Saito, T.R.; Wollersheim, H.J. [GSI, Darmstadt (Germany); Neyens, G.; Mallion, S.; Vermeulen, N. [Inst. voor Kern- en Stralingsfysica, K.U. Leuven (Belgium); Atanasova, L.; Detistov, P. [Univ. of Sofia ' St. Kl. Ohridski' (Bulgaria). Faculty of Physics; Balabanski, D.L. [Univ. degli Studi di Camerino (Italy); INFN sez. Perugia, Dipt. di Fisica, Camerino (Italy); Bulgarian Academy of Sciences, Inst. for Nuclear Research and Nuclear Energy, Sofia (Bulgaria); Bednarczyk, P. [H. Niewodniczanski Inst. of Nuclear Physics PAN, Krakow (Poland); GSI, Darmstadt (Germany); Benzoni, G.; Blasi, N.; Brambilla, S.; Million, B.; Wieland, O. [INFN Sez. di Milano (Italy); Bracco, A.; Camera, F.; Crespi, F.C.L.; Leoni, S.; Montanari, D. [INFN Sez. di Milano (Italy); Univ. degli Studi di Milano (Italy); Chamoli, S.K.; Hass, M.; Lakshmi, S. [Weizman Inst. of Science, Rehovot (Israel); Chmel, S. [Fraunhofer INT, Euskirchen (Germany); Daugas, J.M. [CEA, DAM, DIF, Arpajon Cedex (France); Georgiev, G. [Univ. Paris-Sud 11, CNRS/IN2P3, CSNSM, Orsay-Campus (France); Gladnishki, K. [Univ. of Sofia ' St. Kl. Ohridski' (Bulgaria). Faculty of Physics; Univ. degli Studi di Camerino (Italy); INFN sez. Perugia, Dipt. di Fisica, Camerino (Italy); Hoischen, R.; Rudolph, D. [Lund Univ., Dept. of Physics, Lund (Sweden); Ilie, G. [Univ. zu Koeln, Inst. fuer Kernphysik, Koeln (Germany); National Inst. for Physics and Nuclear Engineering, Bucharest (Romania); Ionescu-Bujor, M. [National Inst. for Physics and Nuclear Engineering, Bucharest (Romania); Jolie, J. [Univ. zu Koeln, Institut fuer Kernphysik, Koeln (Germany)] [and others

    2010-08-15

    The feasibility of measuring g -factors using the TDPAD method applied to high-energy, heavy fragmentation products is explored. The 2623keV I{sup {pi}}=12{sup +} isomer in {sup 192}Pb with {tau}=1.57{mu}s has been produced using the fragmentation of a 1A GeV {sup 238}U beam. The results presented demonstrate for the first time that such heavy nuclei produced in a fragmentation reaction with a relativistic beam are sufficiently well spin-aligned. Moreover, the rather large value of the alignment, 28(10)% of the maximum possible, is preserved during the separation process allowing the determination of magnetic moments. The measured values of the lifetime, {tau}=1.54(9) {mu}s, and the g-factor, g=-0.175(20), agree with the results of previous investigations using fusion-evaporation reactions. (orig.)

  2. Geochemical hosts of solubilized radionuclides in uranium mill tailings

    Science.gov (United States)

    Landa, E.R.; Bush, C.A.

    1990-01-01

    The solubilization and subsequent resorption of radionuclides by ore components or by reaction products during the milling of uranium ores may have both economic and environmental consequences. Particle-size redistribution of radium during milling has been demonstrated by previous investigators; however, the identification of sorbing components in the tailings has received little experimental attention. In this study, uranium-bearing sandstone ore was milled, on a laboratory scale, with sulfuric acid. At regular intervals, filtrate from this suspension was placed in contact with mixtures of quartz sand and various potential sorbents which occur as gangue in uranium ores; the potential sorbents included clay minerals, iron and aluminum oxides, feldspar, fluorspar, barite, jarosite, coal, and volcanic glass. After equilibration, the quartz sand-sorbent mixtures were separated from the filtrate and radioassayed by gamma-spectrometry to determine the quantities of 238U, 230Th, 226Ra, and 210Pb sorbed, and the radon emanation coefficients. Sorption of 238U was low in all cases, with maximal sorptions of 1-2% by the bentonite- and coal-bearing samples. 230Th sorption also was generally less than 1%; maximal sorption here was observed in the fluorspar-bearing sample and appears to be associated with the formation of gypsum during milling. 226Ra and 210 Pb generally showed higher sorption than the other nuclides - more than 60% of the 26Ra solubilized from the ore was sorbed on the barite-bearing sample. The mechanism (s) for this sorption by a wide variety of substrates is not yet understood. Radon emanation coefficients of the samples ranged from about 5 to 30%, with the coal-bearing samples clearly demonstrating an emanating power higher than any of the other materials. ?? 1990.

  3. New Concept For Calculating The Age Of A Fossil Bone By Uranium-Series Method

    Directory of Open Access Journals (Sweden)

    Samer Farkh

    2015-05-01

    Full Text Available Abstract The age of a fossil bone can be determined based on the chain of radioactive uranium as far as it behaves like a closed system. Uranium is incorporated into the bone after its death and disintegrates into thorium. The calculation of age is based on the assumption that living tissue does not contain uranium and at the entrance of uranium in the dead tissue it did not contain thorium. Uranium is soluble in water and easily enters the bone while the thorium adsorbs on the clay soil particles since it is insoluble in water. In this work we determined the equations needed to calculate the age of a bone sample. We have shown that age cannot be determined from the activity ratio between uranium-234 and its source uranium-238 because ratio had to be 1 from 3.5 million years before they both entered the bone. Thus we used the activity ratio of thorium-230 and its source uranium-234 which allowed us to go backward up to 350 000 years. In the case where 234U238U is greater than 1 an amount of exogenous 234U should be deducted.

  4. Lead abundance in the uranium star CS 31082-001

    CERN Document Server

    Plez, B; Cayrel, R; Spite, M; Barbuy, B; Beers, T C; Bonifacio, P; Primas, F; Nordström, B

    2004-01-01

    In a previous paper we were able to measure the abundance of uranium and thorium in the very-metal poor halo giant BPS CS 31082-001, but only obtained an upper limit for the abundance of lead (Pb). We have got from ESO 17 hours of additional exposure on this star in order to secure a detection of the minimum amount of lead expected to be present in CS 31082-001, the amount arising from the decay of the original content of Th and U in the star. We report here this successful detection. We find an LTE abundance log(Pb/H)+12=-0.55 \\pm 0.15 dex, one dex below the upper limits given by other authors for the similar stars CS 22892-052 and BD +17d3248, also enhanced in r-process elements. From the observed present abundances of Th and U in the star, the expected amount of Pb produced by the decay of 232Th, and 238U alone, over 12-15 Gyr is -0.73\\pm 0.17 dex. The decay of 235U is more difficult to estimate, but is probably slightly below the contribution of 238U, making the contribution of the 3 actinides only slight...

  5. Carbon export fluxes and export efficiency in the central Arctic during the record sea-ice minimum in 2012: a joint 234Th/238U and 210Po/210Pb study

    Science.gov (United States)

    Roca-Martí, Montserrat; Puigcorbé, Viena; Rutgers van der Loeff, Michiel M.; Katlein, Christian; Fernández-Méndez, Mar; Peeken, Ilka; Masqué, Pere

    2016-07-01

    The Arctic sea-ice extent reached a record minimum in September 2012. Sea-ice decline increases the absorption of solar energy in the Arctic Ocean, affecting primary production and the plankton community. How this will modulate the sinking of particulate organic carbon (POC) from the ocean surface remains a key question. We use the 234Th/238U and 210Po/210Pb radionuclide pairs to estimate the magnitude of the POC export fluxes in the upper ocean of the central Arctic in summer 2012, covering time scales from weeks to months. The 234Th/238U proxy reveals that POC fluxes at the base of the euphotic zone were very low (2 ± 2 mmol C m-2 d-1) in late summer. Relationships obtained between the 234Th export fluxes and the phytoplankton community suggest that prasinophytes contributed significantly to the downward fluxes, likely via incorporation into sea-ice algal aggregates and zooplankton-derived material. The magnitude of the depletion of 210Po in the upper water column over the entire study area indicates that particle export fluxes were higher before July/August than later in the season. 210Po fluxes and 210Po-derived POC fluxes correlated positively with sea-ice concentration, showing that particle sinking was greater under heavy sea-ice conditions than under partially ice-covered regions. Although the POC fluxes were low, a large fraction of primary production (>30%) was exported at the base of the euphotic zone in most of the study area during summer 2012, indicating a high export efficiency of the biological pump in the central Arctic.

  6. Potential human health risk by metal(loid)s, 234,238U and 210Po due to consumption of fish from the "Luis L. Leon" Reservoir (Northern México).

    Science.gov (United States)

    Luna-Porres, Mayra Y; Rodríguez-Villa, Marco A; Herrera-Peraza, Eduardo F; Renteria-Villalobos, Marusia; Montero-Cabrera, María E

    2014-06-25

    Concentrations of As, Cu, Fe, Hg, Pb and Zn and activity concentrations from 234,238U and 210Po in water, fillet, liver and gills were determined in three stocked fish species from the Luis L. Leon reservoir, located in Northern Mexico. The considered species were Lepomis cyanellus, Cyprinus carpio and Ictalurus furcatus. 238U and 234U activity concentration (AC) in fillet samples showed values of 0.007-0.014 and 0.01-0.02 Bq∙kg-1 wet weight (ww), respectively. Liver samples for L. cyanellus, C. carpio and I. furcatus present 210Po AC of 1.16-3.26, 0.70-1.13 and 0.93-1.37 Bq∙kg-1 ww. Arsenic, mercury and lead concentration intervals in fillet samples were 0.13-0.39, 0.005-0.126 and 0.009-0.08 mg∙kg-1 ww, respectively, while in gill samples they were 0.11-0.43, 0.002-0.039 and 0.02-0.26 mg∙kg-1 ww. The elemental Bioaccumulation Factor (BAF) for fish tissues with respect to their concentrations in water was determined. L. cyanellus showed the highest BAF values for As and total U, being BAFAs = 37 and 40 L∙kg-1 in fillet and gills, respectively, and BAFU total = 1.5 L∙kg-1 in fillet. I. furcatus showed the highest BAF values for Hg and Pb, being BAFHg = 40 and 13 L∙kg-1 in fillet and gills, and BAFPb = 6.5 and 22 L∙kg-1 in fillet and gills, respectively. Some metal(loid) concentrations are slightly higher than European regulations for fish fillets. The difference in concentrations of metal(loid)s in fillet among the studied species is probably due to their differences in diet and habitat.

  7. Distribution of uranium and radium isotopes in an aquifer of a semi-arid region (Manouba-Essijoumi, Northern Tunisia)

    Energy Technology Data Exchange (ETDEWEB)

    Added, A. [Departement de Geologie, Faculte des Sciences de Tunis, Campus Universitaire, 1088 Tunis (Tunisia); Ben Mammou, A. [Departement de Geologie, Faculte des Sciences de Tunis, Campus Universitaire, 1088 Tunis (Tunisia); Fernex, F. [Departement des Sciences de la Terre, Universite de Nice, Valrose, F - 06108 - Nice Cedex 02 (France); Rezzoug, S. [Laboratoire de Radiochimie, Chimie analytique et Environnement, Universite de Nice, Valrose, F - 06108 - Nice Cedex 02 (France); Bernat, M. [Departement des Sciences de la Terre, Universite de Nice, Valrose, F - 06108 - Nice Cedex 02 (France)

    2005-07-01

    Groundwaters from the Sebkhet Essijoumi drainage basin, situated in northern Tunisia, West of the city of Tunis, were sampled and analyzed for uranium and radium isotopes. Low {sup 234}U/{sup 238}U activity ratios coupled with relatively high {sup 228}Ra and {sup 238}U concentrations were found in the Manouba plain phreatic aquifer, at the northern part of the basin, where remote sensing has indicated that this plain corresponds to the main humid zone of the area. Low {sup 234}U/{sup 238}U ratios probably reflected short residence time for waters in the Manouba plain, and high ratios longer residence time in the south, where water reaching the phreatic aquifer seems to have previously circulated in rocks constituting the southern hills. Assuming that, in the Manouba plain aquifer, the groundwater flows downstream from the Oued Lill pass area to the South-West of the Sebkha, the difference in the {sup 228}Ra/{sup 226}Ra activity ratio suggests that the residence time of water has been 2.8 years longer near the Sebkha than upstream.

  8. Distribution of uranium and radium isotopes in an aquifer of a semi-arid region (Manouba-Essijoumi, Northern Tunisia).

    Science.gov (United States)

    Added, A; Ben Mammou, A; Fernex, F; Rezzoug, S; Bernat, M

    2005-01-01

    Groundwaters from the Sebkhet Essijoumi drainage basin, situated in northern Tunisia, West of the city of Tunis, were sampled and analyzed for uranium and radium isotopes. Low (234)U/(238)U activity ratios coupled with relatively high (228)Ra and (238)U concentrations were found in the Manouba plain phreatic aquifer, at the northern part of the basin, where remote sensing has indicated that this plain corresponds to the main humid zone of the area. Low (234)U/(238)U ratios probably reflected short residence time for waters in the Manouba plain, and high ratios longer residence time in the south, where water reaching the phreatic aquifer seems to have previously circulated in rocks constituting the southern hills. Assuming that, in the Manouba plain aquifer, the groundwater flows downstream from the Oued Lill pass area to the South-West of the Sebkha, the difference in the (228)Ra/(226)Ra activity ratio suggests that the residence time of water has been 2.8 years longer near the Sebkha than upstream.

  9. Review and interpretation of previous work and new data on the hydrogeology of the Schwartzwalder Uranium Mine and vicinity, Jefferson County, Colorado

    Science.gov (United States)

    Caine, Jonathan Saul; Johnson, Raymond H.; Wild, Emily C.

    2011-01-01

    (2007), which was to be used as a basis for eventual mine site closure. In 2010 the U.S. Geological Survey was asked by the State of Colorado to provide an objective and independent review of the Wyman and Effner (2007) report and to identify gaps in knowledge regarding the hydrogeology of the mine site. Key findings from the U.S. Geological Survey assessment include geological structural analysis indicating that although the primary uranium-hosting fault likely does not cross under Ralston Creek, many complex subsidiary faults do cross under Ralston Creek. It is unknown if any of these faults act as conduits for mine pool water to enter Ralston Creek. Reported bedrock permeabilities are low, but local hydraulic gradients are sufficient to potentially drive groundwater flow from the mine pool to the creek. Estimated average linear velocities for the full range of reported hydraulic conductivities indicate groundwater transit times from the mine pool to the creek on the order of a few months to about 3,800 years or 11 to 65 years using mean reported input values. These estimates do not account for geochemical reactions along any given flow path that may differentially enhance or retard movement of individual dissolved constituents. New reconnaissance data including 34S isotope and 234U/238U isotopic activity ratios show potentially distinctive signatures for the mine pool compared to local groundwater and Ralston Creek water above the mine site. Although the mine pool may be near an equilibrium elevation, evidence for groundwater recharge transients indicates inflow to the workings that are greater than outflow. There is not enough hydraulic head data adjacent to the mine workings to adequately constrain a final equilibrium elevation or to predict how several wet years in succession might affect variations in mine pool elevation. Although ground level adits are sealed with bulkheads, if the mine pool elevation were to rise slightly to the elevation of or abo

  10. 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

  11. Repository criticality control for {sup 233}U using depleted uranium

    Energy Technology Data Exchange (ETDEWEB)

    Forsberg, C.W.; Elam, K.R.; Hopper, C.M.

    1999-07-01

    The US is evaluating methods for the disposition of excess weapons-usable {sup 233}U, including disposal in a repository. Isotopic dilution studies were undertaken to determine how much depleted uranium (DU) would need to be added to the {sup 233}U to minimize the potential for nuclear criticality in a repository. Numerical evaluations were conducted to determine the nuclear equivalence of different {sup 235}U enrichments to {sup 233}U isotopically diluted with DU containing 0.2 wt% {sup 235}U. A homogeneous system of silicon dioxide, water, {sup 233}U, and DU, in which the ratio of each component was varied, was used to determine the conditions of maximum nuclear reactivity. In terms of preventing nuclear criticality in a repository, there are three important limits from these calculations. 1. Criticality safe in any nonnuclear system: The required isotopic dilution to ensure criticality under all conditions, except in the presence of man-made nuclear materials (beryllium, etc.), is {approximately}1.0% {sup 235}U in {sup 238}U. The equivalent {sup 233}U enrichment level is 0.53 wt% {sup 233}U in DU. 2. Critically safe in natural systems: The lowest {sup 235}U enrichment found in a natural reactor at shutdown was {approximately}1.3%. French studies, based on the characteristics of natural uranium ore bodies, indicate that a minimum enrichment of {approximately}1.28% {sup 235}U is required for criticality. These data suggest that nuclear criticality from migrating uranium is not realistic unless the {sup 235}U enrichments exceed {approximately}1.3%, which is a result that is equivalent to 0.72% {sup 233}U in DU. 3. Criticality safety equivalent to light water reactor (LWR) spent nuclear fuel (SNF): The {sup 233}U can be diluted with DU so that the uranium criticality characteristics match SNF uranium. Whatever repository criticality controls are used for SNF can then be used for {sup 233}U. The average LWR SNF assay (after decay of plutonium isotopes to uranium

  12. 贫铀/聚乙烯交替球壳中裂变反应率的测量与分析%Measurement and Analysis of Fission Rate in Alternate Depleted Uranium/Polyethylene Shells

    Institute of Scientific and Technical Information of China (English)

    严小松; 羊奕伟; 朱通华; 刘荣; 鹿心鑫; 蒋励

    2013-01-01

    In order to check the conceptual design of the subcritical blanket in fusion-fission hybrid reactor, an integral experiment was carried out in alternate depleted uranium/polyethylene shells with 14 MeV neutron using activation technique. The 238U(n,f) and 235U(n,f) reaction rates at 90?direction to the incident D beam were determined by measuring the 293. 3 keV y ray emitted from I43Ce which is generated by 238U(n,f) and 235U(n,f) reactions. The experiment was simulated using MCNP5 code with ENDF/B-Ⅵ library, and the calculated 238U(n,f) and 235U(n,f) reaction rates are generally 5% higher than experimental results.%为校验次临界能源堆的概念设计,采用活化法在贫铀/聚乙烯球壳交替装置上开展14 MeV中子学积分实验.用HPGe探测器测量238U(n,f)及235U(n,f)反应的裂变碎片143Ce衰变产生的293.3 keV特征γ射线,得到装置中与入射D粒子束成90°方向上的238U(n,f)及235U(n,f)反应率分布,相对不确定度为5.1%~6.9%.采用MCNP5程序在ENDF/B-Ⅵ库下进行模拟计算,计算结果较实验结果高约5%.

  13. Radionuclides from past uranium mining in rivers of Portugal.

    Science.gov (United States)

    Carvalho, Fernando P; Oliveira, João M; Lopes, Irene; Batista, Aleluia

    2007-01-01

    During several decades and until a few years ago, uranium mines were exploited in the Centre of Portugal and wastewaters from uranium ore milling facilities were discharged into river basins. To investigate enhancement of radioactivity in freshwater ecosystems, radionuclides of uranium and thorium series were measured in water, sediments, suspended matter, and fish samples from the rivers Vouga, Dão, Távora and Mondego. The results show that these rivers carry sediments with relatively high naturally occurring radioactivity, and display relatively high concentrations of radon dissolved in water, which is typical of a uranium rich region. Riverbed sediments show enhanced concentrations of radionuclides in the mid-section of the Mondego River, a sign of past wastewater discharges from mining and milling works at Urgeiriça confirmed by the enhanced values of (238)U/(232)Th radionuclide ratios in sediments. Radionuclide concentrations in water, suspended matter and freshwater fish from that section of Mondego are also enhanced in comparison with concentrations measured in other rivers. Based on current radionuclide concentrations in fish, regular consumption of freshwater species by local populations would add 0.032 mSv a(-1) of dose equivalent (1%) to the average background radiation dose. Therefore, it is concluded that current levels of enhanced radioactivity do not pose a significant radiological risk either to aquatic fauna or to freshwater fish consumers.

  14. Beam dynamics design for uranium drift tube linear accelerator

    Science.gov (United States)

    Dou, Wei-Ping; He, Yuan; Lu, Yuan-Rong

    2014-07-01

    KONUS beam dynamics design of uranium DTL with LORASR code is presented. The 238U34+ beam, whose current is 5.0 emA, is accelerated from injection energy of 0.35 MeV/u to output energy of 1.30 MeV/u by IH-DTL operated at 81.25 MHz in HIAF project at IMP of CAS. It achieves a transmission efficiency of 94.95% with a cavity length of 267.8 cm. The optimization aims are the reduction of emittance growth, beam loss and project costs. Because of the requirements of CW mode operation, the designed average acceleration gradient is about 2.48 MV/m. The maximum axial field is 10.2 MV/m, meanwhile the Kilpatrick breakdown field is 10.56 MV/m at 81.25 MHz.

  15. KONUS Beam Dynamics Design of Uranium DTL for HIAF

    CERN Document Server

    Dou, W P; Lu, Y R

    2013-01-01

    KONUS beam dynamics design of uranium DTL with LORASR code is presented. The 238U34+ beam, whose current is 5.0emA, is accelerated from injection energy of 0.35MeV/u to output energy of 1.3MeV/u by IH-DTL operated at 81.25MHz in HIAF project at IMP of CAS. It achieves transmission efficiency of 94.95% with the cavity length 267.8cm. Optimization aims are the reduction of emittance growth, of beam loss and of project costs. Because of the requirements of CW mode operation,the designed average acceleration gradient is about 2.48MV/m. Maximum axial filed is 10.2MV/m, meanwhile Kilpatrick breakdown field is 10.56MV/m at 81.25MHz.

  16. Geoquímica de radionuclídeos naturais em solos de áreas circunvizinhas a uma Unidade de Mineração e Atividade de Urânio Geochemistry of natural radionuclide in soils surrounding a Mining and Plant Uranium Concentration

    Directory of Open Access Journals (Sweden)

    Gildevan Viana Cardoso

    2009-12-01

    Full Text Available Os impactos ambientais advindos da exploração e do beneficiamento de U são, em grande parte, idênticos àqueles causados por atividades minero-extrativistas em geral. Este trabalho teve o objetivo de determinar a partição geoquímica dos radionuclídeos naturais 238U, 226Ra e 210Pb em áreas circunvizinhas à Unidade de Mineração e Atividade de Urânio (URA das Indústrias Nucleares do Brasil S.A., localizada na Província Uranífera de Lagoa Real, no município de Caetité, na região sudoeste do Estado da Bahia. Foram coletadas amostras de solo em cinco áreas circunvizinhas à URA, representando as principais classes de solos da região, na profundidade de 0-20 cm. Nas cinco áreas, foram determinados o teor de atividade total e o fracionamento geoquímico nas frações: F1 - levemente ácida, F2 - reduzível, F3 - oxidável, F4 - alcalina e F5 - residual. As atividades totais médias foram, em Bq kg-1 de solo, de 50 para 238U, 51 para 226Ra e 159 para 210Pb. Os extraídos na fase potencialmente biodisponível (F1 foram: 11 % para 238U, 13 % para 226Ra e 3 % para 210Pb. O 238U apresentou maior biodisponibilidade nos solos mais ácidos e maior afinidade pelos óxidos de Fe, o que não ocorreu para o 226Ra, tendo este apresentado a maior biodisponibilidade. O 210Pb apresentouse predominantemente associado a F5. As percentagens elevadas de 238U, 226Ra e 210Pb na fração geoquímica F5 indicam que as atividades observadas nos cinco solos estão, predominantemente, associadas ao material que deu origem a esses solos, e não a um processo de contaminação artificial em função da atividade da URA.The environmental impacts resulting from uranium exploration and processing are to a great extent identical to those caused by extractive mining activities in general. This study aimed to determine the geochemical partitioning of the natural radionuclides 238U, 226Ra and 210Pb in areas surrounding the Uranium Mining and Concentration Plant (URA

  17. Bedrock Geologic Map of Woodstock, Vermont

    Data.gov (United States)

    Vermont Center for Geographic Information — Digital Data from VG06-4 Thompson, P. J., 2006, Bedrock Geologic Map of Woodstock, Vermont: VGS Open-File Report VG06-4, scale 1:24,000. The bedrock geologic map...

  18. The determination of minor isotope abundances in naturally occurring uranium materials. The tracing power of isotopic signatures for uranium

    Energy Technology Data Exchange (ETDEWEB)

    Ovaskainen, R

    1999-11-01

    The mass spectrometric determination of minor abundant isotopes, {sup 234}U and {sup 236}U in naturally occurring uranium materials requires instruments of high abundance sensitivity and the use of highly sensitive detection systems. In this study the thermal ionisation mass spectrometer Finnigan MAT 262RPQ was used. It was equipped with 6 Faraday cups and a Secondary Electron Multiplier (SEM), which was operated in pulse counting mode for the detection of extremely low ion currents. The dynamic measurement range was increased considerably combining these two different detectors. The instrument calibration was performed carefully. The linearity of each detector, the deadtime of the ion counting detector, the detector normalisation factor, the baseline of each detector and the mass discrimination in the ion source were checked and optimised. A measurement technique based on the combination of a Gas Source Mass Spectrometry (GSMS) and a Thermal Ionisation Mass Spectrometry (TIMS) was developed for the accurate determination of isotopic composition in naturally occurring uranium materials. Because the expected ratio of n({sup 234}U)/n({sup 238}U) exceeded the dynamic measurement range of the Faraday detectors of the TIMS instrument, an experimental design using a combination of two detectors was developed. The n({sup 234}U)/n({sup 235}U) and n({sup 236}U)/n({sup 235}U) ratios were determined using ion counting in combination with the decelerating device. The n({sup 235}U)/n({sup 238}U) ratio was determined by the Faraday detector. This experimental design allowed the detector cross calibration to be circumvented. Precisions of less than 1 percent for the n({sup 234}U)/n({sup 235}U) ratios and 5-25 percent for the n({sup 236}U)/n({sup 235}U) ratios were achieved. The purpose of the study was to establish a register of isotopic signatures for natural uranium materials. The amount ratio, and isotopic composition of 18 ore concentrates, collected by the International

  19. 1.4MeV-5MeV中子诱发238U裂变产额测量%Fission Product Yield Measurement of 238 U Induced by 1.4-5 MeV Neutrons

    Institute of Scientific and Technical Information of China (English)

    李映映; 肖军; 王攀; 李子越; 汪超; 罗小兵

    2016-01-01

    238 U fission yield measurement has a significant meaning in nuclear data measurement .This thesis a-dopts1.4 MeV-5 MeV mono -energetic neutrons generated by 2.5 MeV proton electrostatic accelerator to stimulate 238U fission, and then measures the yield of fission product nuclide 135I、133I、105Ru and 91Sr through measuring fission product radioactivity .Neutron flux during irradiation process is determined by activation meth-od .Subsequently , this thesis analyzes multiple components influencing experiment measurement , including cor-rection on neutron′s multiple scattering and self -shielding effect in target head and sample on the basis of MC-NPX program as well as correction on sample′s self-absorption of γ-ray.Typical deviation of yield data is concluded as 3.5%.Finally, this thesis compares measurement consequences with existing fission yield data .%238 U裂变产额测量工作在核数据测量中有着重要意义,本工作利用2.5MeV质子静电加速器产生的1.4MeV-5MeV单能中子诱发238 U裂变,通过对裂变产物放射性的测量对裂变产物核素135 I、133 I、105 Ru和91 Sr的产额进行了测定。照射过程中中子通量用活化法确定。分析了影响实验测量的多个因素,包括用MCNPX程序对中子在靶头及样品中的多次散射和自屏蔽效应进行了修正,对γ射线在样品中的自吸收进行修正等。得到产额数据典型误差为3.5%,最后把测量结果与已有的裂变产额数据进行比对。

  20. Potential Human Health Risk by Metal(loid)s, 234,238U and 210Po due to Consumption of Fish from the “Luis L. Leon” Reservoir (Northern México)

    Science.gov (United States)

    Luna-Porres, Mayra Y.; Rodríguez-Villa, Marco A.; Herrera-Peraza, Eduardo F.; Renteria-Villalobos, Marusia; Montero-Cabrera, María E.

    2014-01-01

    Concentrations of As, Cu, Fe, Hg, Pb and Zn and activity concentrations from 234,238U and 210Po in water, fillet, liver and gills were determined in three stocked fish species from the Luis L. Leon reservoir, located in Northern Mexico. The considered species were Lepomis cyanellus, Cyprinus carpio and Ictalurus furcatus. 238U and 234U activity concentration (AC) in fillet samples showed values of 0.007–0.014 and 0.01–0.02 Bq∙kg−1 wet weight (ww), respectively. Liver samples for L. cyanellus, C. carpio and I. furcatus present 210Po AC of 1.16–3.26, 0.70–1.13 and 0.93–1.37 Bq∙kg−1 ww. Arsenic, mercury and lead concentration intervals in fillet samples were 0.13–0.39, 0.005–0.126 and 0.009–0.08 mg∙kg−1 ww, respectively, while in gill samples they were 0.11–0.43, 0.002–0.039 and 0.02–0.26 mg∙kg−1 ww. The elemental Bioaccumulation Factor (BAF) for fish tissues with respect to their concentrations in water was determined. L. cyanellus showed the highest BAF values for As and total U, being BAFAs = 37 and 40 L∙kg−1 in fillet and gills, respectively, and BAFU total = 1.5 L∙kg−1 in fillet. I. furcatus showed the highest BAF values for Hg and Pb, being BAFHg = 40 and 13 L∙kg−1 in fillet and gills, and BAFPb = 6.5 and 22 L∙kg−1 in fillet and gills, respectively. Some metal(loid) concentrations are slightly higher than European regulations for fish fillets. The difference in concentrations of metal(loid)s in fillet among the studied species is probably due to their differences in diet and habitat. PMID:24968208

  1. Potential Human Health Risk by Metal(loids, 234,238U and 210Po due to Consumption of Fish from the “Luis L. Leon” Reservoir (Northern México

    Directory of Open Access Journals (Sweden)

    Mayra Y. Luna-Porres

    2014-06-01

    Full Text Available Concentrations of As, Cu, Fe, Hg, Pb and Zn and activity concentrations from 234,238U and 210Po in water, fillet, liver and gills were determined in three stocked fish species from the Luis L. Leon reservoir, located in Northern Mexico. The considered species were Lepomis cyanellus, Cyprinus carpio and Ictalurus furcatus. 238U and 234U activity concentration (AC in fillet samples showed values of 0.007–0.014 and 0.01–0.02 Bq∙kg−1 wet weight (ww, respectively. Liver samples for L. cyanellus, C. carpio and I. furcatus present 210Po AC of 1.16–3.26, 0.70–1.13 and 0.93–1.37 Bq∙kg−1 ww. Arsenic, mercury and lead concentration intervals in fillet samples were 0.13–0.39, 0.005–0.126 and 0.009–0.08 mg∙kg−1 ww, respectively, while in gill samples they were 0.11–0.43, 0.002–0.039 and 0.02–0.26 mg∙kg−1 ww. The elemental Bioaccumulation Factor (BAF for fish tissues with respect to their concentrations in water was determined. L. cyanellus showed the highest BAF values for As and total U, being BAFAs = 37 and 40 L∙kg−1 in fillet and gills, respectively, and BAFU total = 1.5 L∙kg−1 in fillet. I. furcatus showed the highest BAF values for Hg and Pb, being BAFHg = 40 and 13 L∙kg−1 in fillet and gills, and BAFPb = 6.5 and 22 L∙kg−1 in fillet and gills, respectively. Some metal(loid concentrations are slightly higher than European regulations for fish fillets. The difference in concentrations of metal(loids in fillet among the studied species is probably due to their differences in diet and habitat.

  2. The cumulative effect of three decades of phosphogypsum amendments in reclaimed marsh soils from SW Spain: {sup 226}Ra, {sup 238}U and Cd contents in soils and tomato fruit

    Energy Technology Data Exchange (ETDEWEB)

    Abril, Jose-Maria [Dpto. Fisica Aplicada I, Universidad de Sevilla, EUITA, Ctra Utrera Km 1, 41013 Seville (Spain); Garcia-Tenorio, Rafael [Dpto. Fisica Aplicada II, Universidad de Sevilla, ETSA, Avda. Reina Mercedes s/n, 41012 Seville (Spain); Enamorado, Santiago M. [Dpto. Fisica Aplicada I, Universidad de Sevilla, EUITA, Ctra Utrera Km 1, 41013 Seville (Spain); Hurtado, M. Dolores; Andreu, Luis; Delgado, Antonio [Dpto. Ciencias Agroforestales, Universidad de Sevilla, EUITA, Ctra Utrera Km 1, 41013, Seville (Spain)

    2008-09-15

    Phosphogypsum (PG), a by-product of the phosphate fertiliser industries, has been applied as soil amendment to reduce Na saturation in soils, as in the reclaimed marsh area from SW Spain, where available PG has a typical fingerprint of 710 {+-} 40 Bq kg{sup -1} of {sup 226}Ra, 165 {+-} 15 Bq kg{sup -1} of {sup 238}U and 2.8 {+-} 0.4 mg kg{sup -1} of Cd. This work was focussed on the cumulative effects of PG amendments on the enrichment of these pollutants in cultivated soils and plants (Lycopersicum esculentum Mill L.) from the area studied, where PG has been applied since 1978 at recommended rates of 20-25 Mg ha{sup -1} every 2-3 years. A field experiment was conducted over three years to compare activity concentrations of {sup 226}Ra ({sup 214}Pb) and {sup 238}U ({sup 234}Th) in non-reclaimed soils, reclaimed soils with no additional PG application, and reclaimed soils with two additional PG applications. A non-significant effect of two PG amendments (in three years) was observed when compared with non-amended reclaimed plots. Nevertheless, a significant (p < 0.05) enrichment of {sup 226}Ra was observed in the surface horizon (0-30 cm) of reclaimed plots relative to deeper horizons and also when compared with the surface horizon of non-reclaimed soil (p < 0.05), thereby revealing the cumulative effect of three decades of PG applications. Furthermore, the effect of a continuous application of PG was studied by analysing soils and tomato fruits from six commercial farms with different cumulative rates of PG applied. Cadmium concentrations in tomatoes, which were one order of magnitude higher than those found in tomatoes from other areas in South Spain, were positively correlated (r = 0.917*) with {sup 226}Ra-concentration in soils, which can be considered an accurate index of the cumulative PG rate of each farm.

  3. 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

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Fernando Brenha E-mail: brenha@iag.usp.br; Roque, Arnaldo; Boggiani, Paulo Cesar; Flexor, J.-M

    2001-01-15

    Activities of gamma-ray emitting members of the uranium ({sup 238}U) and thorium ({sup 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 {sup 238}U/{sup 226}Ra and {sup 228}Th/{sup 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.

  4. Uranium isotope composition of a laterite profile during extreme weathering of basalt in Guangdong, South China

    Science.gov (United States)

    Huang, J.; Zhou, Z.; Gong, Y.; Lundstrom, C.; Huang, F.

    2015-12-01

    Rock weathering and soil formation in the critical zone are important for material cycle from the solid Earth to superficial system. Laterite is a major type of soil in South China forming at hot-humid climate, which has strong effect on the global uranium cycle. Uranium is closely related to the environmental redox condition because U is stable at U(Ⅳ) in anoxic condition and U(Ⅵ) as soluble uranyl ion (UO22+) under oxic circumstance. In order to understand the behavior of U isotopes during crust weathering, here we report uranium isotopic compositions of soil and base rock samples from a laterite profile originated from extreme weathering of basalt in Guangdong, South China. The uranium isotopic data were measured on a Nu Plasma MC-ICP-MS at the University of Illinois at Urbana-Champaign using the double spike method. The δ238U of BCR-1 is -0.29±0.03‰ (relative to the international standard CRM-112A), corresponding to a 238U/235U ratio of 137.911±0.004. Our result of BCR-1 agrees with previous analyses (e.g., -0.28‰ in Weyer et al. 2008) [1]. U contents of the laterite profile decrease from 1.9 ppm to 0.9 ppm with depth, and peak at 160 - 170 cm (2.3 ppm), much higher than the U content of base rocks (~0.5 ppm). In contrary, U/Th of laterites is lower than that of base rock (0.27) except the peak at the depth of 160-170 cm (0.38), indicating significant U loss during weathering. Notably, U isotope compositions of soils show a small variation from -0.38 to -0.28‰, consistent with the base rock within analytical error (0.05‰ to 0.08‰, 2sd). Such small variation can be explained by a "rind effect" (Wang et al., 2015) [2], by which U(Ⅳ) can be completely oxidized to U(VI) layer by layer during basalt weathering by dissolved oxygen. Therefore, our study indicates that U loss during basalt weathering at the hot-humid climate does not change U isotope composition of superficial water system. [1] Weyer S. et al. (2008) Natural fractionation of 238U/235

  5. Bedrock Hydrogeology - Site investigation SFR

    Energy Technology Data Exchange (ETDEWEB)

    Oehman, Johan [Geosigma AB, Stockholm (Sweden); Bockgaard, Niclas [Golder Assoes AB, Stockholm (Sweden); Follin, Sven [SF GeoLogic AB, Taeby (Sweden)

    2012-06-15

    The Swedish Nuclear Fuel and Waste Management Company (SKB) has conducted site investigations for a planned extension of the existing final repository for short-lived radioactive waste (SFR). This report presents an integrated analysis and interpretation of the historic data from the existing SFR (1980 - 1986), as well as, from the recent investigations for the planned extension of SFR (2008 - 2009). The primary objective is to establish a conceptual hydrogeological model of the bedrock for safety assessment and design analyses. Analyses and interpretations of all (old and new) hydraulic data are analysed with regard to the recently developed geological deformation zone model of the SFR model domain (Curtis et al. 2011). The methodology used by Curtis et al. (2011) has focussed on magnetic anomalies and deformation zone intercepts with ground surface greater than 300 m. In the hydrogeological modelling, however, it has been considered important to also explore the occurrence and characteristics of shallow horizontal to sub-horizontal structures (sheet joints) inside the SFR model domain. Such structures are of considerable importance for the hydrogeology in the uppermost c. 150 m of bedrock in SDM-Site Forsmark; hence the term Shallow Bedrock Aquifer was used to emphasise their hydraulic significance. In this study, the acronym SBA-structure is used for horizontal structures identified in the hydrogeological modelling. In addition to the predominantly steeply dipping geological deformation zones, eight so-called SBA-structures are modelled deterministically in the hydrogeological model. The SBA-structures are envisaged as hydraulically heterogeneous and composed of clusters of minor gently dipping to horizontal fractures rather than extensive single features. A type of structures that is partly included in the definition of the SBA-structures is the Unresolved Possible Deformations Zone (Unresolved PDZ) intercepts identified by Curtis et al. (2011). The Unresolved

  6. Environmental isotopes as a useful tool for studies at mixed uranium mill tailings sites.

    Science.gov (United States)

    Helling, C

    2000-01-01

    Groundwaters in the area of a mixed landfill (domestic waste above uranium mill tailings) in Dresden (Saxony, Germany) were investigated for their isotope signatures to distinguish between different groundwater types. To determine between the two contamination sources (waste and uranium mill tailings) a multi parameter interpretation was done using both, the main hydrochemical parameters the radionuclides 234U, 238U, 226Ra and 222Rn as well as the environmental isotopes of the elements hydrogen, oxygen, sulphur and carbon. The seepage water from the landfill shows higher delta34S, delta18O and tritium values as the inflow. The tritium values give an idea about water movement in the dump and mean residence time of the groundwater. The water in the dump shows varying delta13C values which indicate different processes occurring in the dump.

  7. Neutron Resonance Parameters of 238U and the Calculated Cross Sections from the Reich-Moore Analysis of Experimental Data in the Neutron Energy Range from 0 keV to 20 keV

    Energy Technology Data Exchange (ETDEWEB)

    Derrien, H

    2005-12-05

    The neutron resonance parameters of {sup 238}U were obtained from a SAMMY analysis of high-resolution neutron transmission measurements and high-resolution capture cross section measurements performed at the Oak Ridge Electron Linear Accelerator (ORELA) in the years 1970-1990, and from more recent transmission and capture cross section measurements performed at the Geel Linear Accelerator (GELINA). Compared with previous evaluations, the energy range for this resonance analysis was extended from 10 to 20 keV, taking advantage of the high resolution of the most recent ORELA transmission measurements. The experimental database and the method of analysis are described in this report. The neutron transmissions and the capture cross sections calculated with the resonance parameters are compared with the experimental data. A description is given of the statistical properties of the resonance parameters and of the recommended values of the average parameters. The new evaluation results in a slight decrease of the effective capture resonance integral and improves the prediction of integral thermal benchmarks by 70 pcm to 200 pcm.

  8. Beta and gamma decay heat measurements between 0.1s-50,000s for neutron fission of {sup 235}U, {sup 238}U and {sup 239}Pu. Progress report, March 1, 1993--January 31, 1994

    Energy Technology Data Exchange (ETDEWEB)

    Schier, W.A.; Couchell, G.P.

    1994-06-01

    Decay heat measurements following the fast fission of {sup 238}U are well underway. The He-jet system and spectrometers were moved to the 1 MW research reactor to gain sufficient fast neutron flux for these measurements. On the Van de Graaff accelerator, the He-jet capillary has been shortened so that beta and gamma measurements following the thermal neutron fission of {sup 235}U could be made down to delay times near 0.1 s. Gamma-ray response functions are now well characterized for gamma energies up to 1.5 MeV for our large Nal spectrometer. Such response functions out to high energies are needed to extract energy distributions of our measured gamma spectra. The response function unfolding program, FERD-PC, has been operated successfully with trial spectra. Comparisons of individual fission products for {sup 235}U(n{sub th}f) with ENDF/B-VI at short delay times suggest several improvements to the data base particularly in production probabilities. The new data acquisition and data analysis systems have arrived and will soon be brought on line extending considerably the capabilities of our research group.

  9. Estimation of covariances of {sup 16}O, {sup 23}Na, Fe, {sup 235}U, {sup 238}U and {sup 239}Pu neutron nuclear data in JENDL-3.2

    Energy Technology Data Exchange (ETDEWEB)

    Shibata, Keiichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Nakajima, Yutaka; Kawano, Toshihiko; Oh, Soo-Youl; Matsunobu, Hiroyuki; Murata, Toru

    1997-10-01

    Covariances of nuclear data have been estimated for 6 nuclides contained in JENDL-3.2. The nuclides considered are {sup 16}O, {sup 23}Na, Fe, {sup 235}U, {sup 238}U, and {sup 239}Pu, which are regarded as important for the nuclear design study of fast reactors. The physical quantities for which covariances are deduced are cross sections, resolved and unresolved resonance parameters, and the first order Legendre-polynomial coefficient for the angular distribution of elastically scattered neutrons. As for {sup 235}U, covariances were obtained also for the average number of neutrons emitted in fission. The covariances were estimated by using the same methodology that had been used in the JENDL-3.2 evaluation in order to keep a consistency between mean values and their covariances. The least-squares fitting code GMA was used in estimating covariances for reactions of which JENDL-3.2 cross sections had been evaluated by taking account of measurements. In nuclear model calculations, the covariances were calculated by the KALMAN system. The covariance data obtained were compiled in the ENDF-6 format, and will be put into the JENDL-3.2 Covariance File which is one of JENDL special purpose files. (author). 193 refs.

  10. Estimation of multi-group cross section covariances for {sup 235,238}U, {sup 239}Pu, {sup 241}Am, {sup 56}Fe, {sup 23}Na and {sup 27}Al

    Energy Technology Data Exchange (ETDEWEB)

    De Saint Jean, C.; Archier, P.; Noguere, G.; Litaize, O.; Vaglio-Gaudard, C.; Bernard, D.; Leray, O. [CEA, DEN, DER, Cadarache, F-13108 Saint-Paul-lez-Durance (France)

    2012-07-01

    This paper presents the methodology used to estimate multi-group covariances for some major isotopes used in reactor physics. The starting point of this evaluation is the modelling of the neutron induced reactions based on nuclear reaction models with parameters. These latest are the vectors of uncertainties as they are absorbing uncertainties and correlation arising from the confrontation of nuclear reaction model to microscopic experiment. These uncertainties are then propagated towards multi-group cross sections. As major breakthroughs were then asked by nuclear reactor physicists to assess proper uncertainties to be used in applications, a solution is proposed by the use of integral experiment information at two different stages in the covariance estimation. In this paper, we will explain briefly the treatment of all type of uncertainties, including experimental ones (statistical and systematic) as well as those coming from validation of nuclear data on dedicated integral experiment (nuclear data oriented). We will illustrate the use of this methodology with various isotopes such as {sup 235,238}U, {sup 239}Pu, {sup 241}Am, {sup 56}Fe, {sup 23}Na and {sup 27}Al. (authors)

  11. Uranium Bio-accumulation and Cycling as revealed by Uranium Isotopes in Naturally Reduced Sediments from the Upper Colorado River Basin

    Science.gov (United States)

    Lefebvre, Pierre; Noël, Vincent; Jemison, Noah; Weaver, Karrie; Bargar, John; Maher, Kate

    2016-04-01

    Uranium (U) groundwater contamination following oxidized U(VI) releases from weathering of mine tailings is a major concern at numerous sites across the Upper Colorado River Basin (CRB), USA. Uranium(IV)-bearing solids accumulated within naturally reduced zones (NRZs) characterized by elevated organic carbon and iron sulfide compounds. Subsequent re-oxidation of U(IV)solid to U(VI)aqueous then controls the release to groundwater and surface water, resulting in plume persistence and raising public health concerns. Thus, understanding the extent of uranium oxidation and reduction within NRZs is critical for assessing the persistence of the groundwater contamination. In this study, we measured solid-phase uranium isotope fractionation (δ238/235U) of sedimentary core samples from four study sites (Shiprock, NM, Grand Junction, Rifle and Naturita, CO) using a multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS). We observe a strong correlation between U accumulation and the extent of isotopic fractionation, with Δ238U up to +1.8 ‰ between uranium-enriched and low concentration zones. The enrichment in the heavy isotopes within the NRZs appears to be especially important in the vadose zone, which is subject to variations in water table depth. According to previous studies, this isotopic signature is consistent with biotic reduction processes associated with metal-reducing bacteria. Positive correlations between the amount of iron sulfides and the accumulation of reduced uranium underline the importance of sulfate-reducing conditions for U(IV) retention. Furthermore, the positive fractionation associated with U reduction observed across all sites despite some variations in magnitude due to site characteristics, shows a regional trend across the Colorado River Basin. The maximum extent of 238U enrichment observed in the NRZ proximal to the water table further suggests that the redox cycling of uranium, with net release of U(VI) to the groundwater by

  12. SFR site investigation. Bedrock Hydrogeochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Nilsson, Ann-Chatrin [Geosigma AB, Uppsala (Sweden); Tullborg, Eva-Lena [Terralogica AB, Graabo (Sweden); Smellie, John [Conterra AB, Uppsala (Sweden); Gimeno, Maria J.; Gomez, Javier B.; Auque, Luis F. [Univ. of Zaragoza, Zaragoza (Spain); Sandstroem, Bjoern [WSP Sverige AB, Goeteborg (Sweden); Pedersen, Karsten [Micans AB, Moelnlycke (Sweden)

    2011-11-15

    There are plans that the final repository for low and intermediate level radioactive waste, SFR, located about 150 km north of Stockholm, will be extended. Geoscientific studies to define and characterise a suitable bedrock volume for the extended repository have been carried out from 2007 to 2011, and have included the drilling and evaluation of seven new core drilled and four percussion boreholes. These new data, together with existing data extending back to 1985, have been interpreted and modelled in order to provide the necessary information for safety assessment and repository design. This report presents the final hydrogeochemical site description for the SFR site, and will constitute a background report for the integrated site description (the SFR Site Descriptive Model version 1.0) together with corresponding reports from the geological and hydrogeological disciplines. Most of the hydrogeochemical data from the field investigations consist of major ions and isotopes together with sporadic gas, microbe and measured redox data. Despite the close proximity of the Forsmark site, few data from this source are of relevance because of the shallow nature of the SFR site, the fact that SFR is located beneath the Baltic Sea and also the drawdown/upconing impacts of its construction on the hydrogeochemistry. This artificially imposed dynamic flow system is naturally more prevalent along major deformation fracture zones of higher transmissivity, whilst lower transmissive fractures together with the less transmissive bedrock masses between major deformation zones, still retain some evidence of the natural groundwater mixing patterns established prior to the SFR construction. The groundwaters in the SFR dataset cover a depth down to -250 m.a.s.l. with single sampling locations at -300 and -400 m.a.s.l. and represent a relatively limited salinity range (1,500 to 5,500 mg/L chloride). However, the {delta}{sup 18}O values show a wide variation (-15.5 to -7.5 per mille V

  13. Depth to Bedrock: Isopach of Unconsolidated Materials

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — This vector dataset gives the approximate depth to bedrock (in feet) from Iowa's current land surface. This 50 foot isopach data was derived from the Digital...

  14. Uranium and Sm isotope studies of the supergiant Olympic Dam Cu-Au-U-Ag deposit, South Australia

    Science.gov (United States)

    Kirchenbaur, Maria; Maas, Roland; Ehrig, Kathy; Kamenetsky, Vadim S.; Strub, Erik; Ballhaus, Chris; Münker, Carsten

    2016-05-01

    The Olympic Dam Cu-U-Au-Ag deposit in the Archean-Proterozoic Gawler Craton (South Australia) is a type example of the iron oxide-copper-gold (IOCG) spectrum of deposits and one of the largest Cu-U-Au resources known. Mineralization is hosted in a lithologically and texturally diverse, hematite-rich breccia complex developed within a granite of the 1.59 Ga Gawler Silicic Province. Emerging evidence indicates that both the breccia complex and its metal content developed over ∼1000 Ma, responding to major tectonic events, e.g., at 1300-1100, 825 and 500 Ma. However, metal sources and exact mechanism/s of ore formation remain poorly known. New high-precision 238U/235U data for a set of 40 whole rock samples representing all major lithological facies of the breccia complex show a narrow range (δ238UCRM112a = -0.56‰ to +0.04‰). At the scale of sampling, there is no correlation of δ238U with lithology, degree of alteration or U mineralogy, although ores with U > 5 wt.% have subtly higher δ238U values (-0.20‰ to 0.00) than the majority of samples (5 wt.% U, U/Sm ≫ 500) Olympic Dam ores define a neutron capture line, with correlated depletions in 149Sm (up to ∼2ε units) and excesses in 150Sm (up to ∼ 4ε units), but fission fragment contributions to Sm are below detection. These observations provide evidence for small-scale neutron-capture effects, with calculated neutron fluences of 1015 to 1016 n cm-2, similar to those observed in several Proterozoic and Phanerozoic U deposits. The apparent lack of fission fragment contributions in Olympic Dam high-grade ores can be explained with an age of U deposition, or re-deposition that is substantially younger than the initial 1.59 Ga age of the oldest IOCG-style mineralization. The results presented here thus (i) suggest uranium sources in common (likely igneous) upper crustal lithologies, (ii) support geochronological evidence for gradual addition of U in several stages over 1000 Ma at elevated temperatures of

  15. Uranium partition coefficients (Kd) in forest surface soil reveal long equilibrium times and vary by site and soil size fraction.

    Science.gov (United States)

    Whicker, Jeffrey J; Pinder, John E; Ibrahim, Shawki A; Stone, James M; Breshears, David D; Baker, Kristine N

    2007-07-01

    The environmental mobility of newly deposited radionuclides in surface soil is driven by complex biogeochemical relationships, which have significant impacts on transport pathways. The partition coefficient (Kd) is useful for characterizing the soil-solution exchange kinetics and is an important factor for predicting relative amounts of a radionuclide transported to groundwater compared to that remaining on soil surfaces and thus available for transport through erosion processes. Measurements of Kd for 238U are particularly useful because of the extensive use of 238U in military applications and associated testing, such as done at Los Alamos National Laboratory (LANL). Site-specific measurements of Kd for 238U are needed because Kd is highly dependent on local soil conditions and also on the fine soil fraction because 238U concentrates onto smaller soil particles, such as clays and soil organic material, which are most susceptible to wind erosion and contribute to inhalation exposure in off-site populations. We measured Kd for uranium in soils from two neighboring semiarid forest sites at LANL using a U.S. Environmental Protection Agency (EPA)-based protocol for both whole soil and the fine soil fraction (diametersKd values, which are those specified in the EPA protocol, ranged from 276-508 mL g-1 for whole soil and from 615-2249 mL g-1 for the fine soil fraction. Unexpectedly, the 30-d Kd values, measured to test for soil-solution exchange equilibrium, were more than two times the 7-d values. Rates of adsorption of 238U to soil from solution were derived using a 2-component (FAST and SLOW) exponential model. We found significant differences in Kd values among LANL sampling sites, between whole and fine soils, and between 7-d and 30-d Kd measurements. The significant variation in soil-solution exchange kinetics among the soils and soil sizes promotes the use of site-specific data for estimates of environmental transport rates and suggests possible differences in

  16. 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 238U/235U isotopic composition of uranium in seawater can provide important insights into the modern U budget of the oceans. Using the double spike technique and a new data reduction method, we analyzed an array of seawater samples and 41 geostandards covering a broad range of geological settings relevant to low and high temperature geochemistry. Analyses of 18 seawater samples from geographically diverse sites from the Atlantic and Pacific oceans, Mediterranean Sea, Gulf of Mexico, Persian Gulf, and English Channel, together with literature data (n = 17), yield a δ238U value for modern seawater of -0.392 ± 0.005‰ relative to CRM-112a. Measurements of the uranium isotopic compositions of river water, lake water, evaporites, modern coral, shales, and various igneous rocks (n = 64), together with compilations of literature data (n = 380), allow us to estimate the uranium isotopic compositions of the various reservoirs involved in the modern oceanic uranium budget, as well as the fractionation factors associated with U incorporation into those reservoirs. Because the incorporation of U into anoxic/euxinic sediments is accompanied by large isotopic fractionation (ΔAnoxic/Euxinic-SW = +0.6‰), the size of the anoxic/euxinic sink strongly influences the δ238U value of seawater. Keeping all other fluxes constant, the flux of uranium in the anoxic/euxinic sink is constrained to be 7.0 ± 3.1 Mmol/yr (or 14 ± 3% of the total flux out of the ocean). This translates into an areal extent of anoxia into the modern ocean of 0.21 ± 0.09% of the total seafloor. This agrees with independent estimates and rules out a recent uranium budget estimate by Henderson and Anderson (2003). Using the mass fractions and isotopic compositions of various rock types in Earth's crust, we further calculate an average δ238U isotopic composition for the continental crust of -0.29 ± 0.03‰ corresponding to a 238U/235U isotopic ratio of 137.797 ± 0.005. We discuss the implications of

  17. Simulated fissioning of uranium and testing of the fission-track dating method

    Science.gov (United States)

    McGee, V.E.; Johnson, N.M.; Naeser, C.W.

    1985-01-01

    A computer program (FTD-SIM) faithfully simulates the fissioning of 238U with time and 235U with neutron dose. The simulation is based on first principles of physics where the fissioning of 238U with the flux of time is described by Ns = ??f 238Ut and the fissioning of 235U with the fluence of neutrons is described by Ni = ??235U??. The Poisson law is used to set the stochastic variation of fissioning within the uranium population. The life history of a given crystal can thus be traced under an infinite variety of age and irradiation conditions. A single dating attempt or up to 500 dating attempts on a given crystal population can be simulated by specifying the age of the crystal population, the size and variation in the areas to be counted, the amount and distribution of uranium, the neutron dose to be used and its variation, and the desired ratio of 238U to 235U. A variety of probability distributions can be applied to uranium and counting-area. The Price and Walker age equation is used to estimate age. The output of FTD-SIM includes the tabulated results of each individual dating attempt (sample) on demand and/or the summary statistics and histograms for multiple dating attempts (samples) including the sampling age. An analysis of the results from FTD-SIM shows that: (1) The external detector method is intrinsically more precise than the population method. (2) For the external detector method a correlation between spontaneous track count, Ns, and induced track count, Ni, results when the population of grains has a stochastic uranium content and/or when the counting areas between grains are stochastic. For the population method no correlation can exist. (3) In the external detector method the sampling distribution of age is independent of the number of grains counted. In the population method the sampling distribution of age is highly dependent on the number of grains counted. (4) Grains with zero-track counts, either in Ns or Ni, are in integral part of

  18. Modeling non-steady state radioisotope transport in the vadose zone--A case study using uranium isotopes at Pena Blanca, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Ku, T. L.; Luo, S.; Goldstein, S. J.; Murrell, M. T.; Chu, W. L.; Dobson, P. F.

    2009-06-01

    Current models using U- and Th-series disequilibria to study radioisotope transport in groundwater systems mostly consider a steady-state situation. These models have limited applicability to the vadose zone (UZ) where the concentration and migratory behavior of radioisotopes in fluid are often transitory. We present here, as a first attempt of its kind, a model simulating the non-steady state, intermittent fluid transport in vadose layers. It provides quantitative constraints on in-situ migration of dissolved and colloidal radioisotopes in terms of retardation factor and rock-water interaction (or water transit) time. For uranium, the simulation predicts that intermittent flushing in the UZ leads to a linear relationship between reciprocal U concentration and {sup 234}U/{sup 238}U ratio in percolating waters, with the intercept and slope bearing information on the rates of dissolution and {alpha}-recoil of U isotopes, respectively. The general validity of the model appears to be borne out by the measurement of uranium isotopes in UZ waters collected at various times over a period during 1995-2006 from a site in the Pena Blanca mining district, Mexico, where the Nopal I uranium deposit is located. Enhanced {sup 234}U/{sup 238}U ratios in vadose-zone waters resulting from lengthened non-flushing time as prescribed by the model provide an interpretative basis for using {sup 234}U/{sup 238}U in cave calcites to reconstruct the regional changes in hydrology and climate. We also provide a theoretical account of the model's potential applications using radium isotopes.

  19. Modeling non-steady state radioisotope transport in the vadose zone - A case study using uranium isotopes at Peña Blanca, Mexico

    Science.gov (United States)

    Ku, T. L.; Luo, S.; Goldstein, S. J.; Murrell, M. T.; Chu, W. L.; Dobson, P. F.

    2009-10-01

    Current models using U- and Th-series disequilibria to study radioisotope transport in groundwater systems mostly consider a steady-state situation. These models have limited applicability to the vadose zone (UZ) where the concentration and migratory behavior of radioisotopes in fluid are often transitory. We present here, as a first attempt of its kind, a model simulating the non-steady state, intermittent fluid transport in vadose layers. It provides quantitative constraints on in-situ migration of dissolved and colloidal radioisotopes in terms of retardation factor and rock-water interaction (or water transit) time. For uranium, the simulation predicts that intermittent flushing in the UZ leads to a linear relationship between reciprocal U concentration and 234U/ 238U ratio in percolating waters, with the intercept and slope bearing information on the rates of dissolution and α-recoil of U isotopes, respectively. The general validity of the model appears to be borne out by the measurement of uranium isotopes in UZ waters collected at various times over a period during 1995-2006 from a site in the Peña Blanca mining district, Mexico, where the Nopal I uranium deposit is located. Enhanced 234U/ 238U ratios in vadose-zone waters resulting from lengthened non-flushing time as prescribed by the model provide an interpretative basis for using 234U/ 238U in cave calcites to reconstruct the regional changes in hydrology and climate. We also provide a theoretical account of the model's potential applications using radium isotopes.

  20. Measurement of the isotopic composition of uranium micrometer-size particles by femtosecond laser ablation-inductively coupled plasma mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Hubert, Amélie, E-mail: amelie.hubert@cea.fr [CEA, DAM, DIF, F-91297 Arpajon (France); Claverie, Fanny [Laboratoire de Chimie Analytique Bio-Inorganique et Environnement, UMR 5254, Hélioparc Pau-Pyrénées, 2 Avenue du Président Angot, 64053 Pau (France); Novalase SA, ZI de la Briqueterie, 6 Impasse du Bois de la Grange, 33610 Canejan (France); Pécheyran, Christophe [Laboratoire de Chimie Analytique Bio-Inorganique et Environnement, UMR 5254, Hélioparc Pau-Pyrénées, 2 Avenue du Président Angot, 64053 Pau (France); Pointurier, Fabien [CEA, DAM, DIF, F-91297 Arpajon (France)

    2014-03-01

    In this paper, we will describe and indicate the performance of a new method based on the use of femtosecond laser ablation (fs-LA) coupled to a quadrupole-based inductively coupled plasma mass spectrometer (ICP-QMS) for analyzing the isotopic composition of micrometer-size uranium particles. The fs-LA device was equipped with a high frequency source (till 10 kHz). We applied this method to 1–2 μm diameter-uranium particles of known isotopic composition and we compared this technique with the two techniques currently used for uranium particle analysis: Secondary Ionization Mass Spectrometry (SIMS) and Fission Track Thermal Ionization Mass Spectrometry (FT-TIMS). By optimizing the experimental conditions, we achieved typical accuracy and reproducibility below 4% on {sup 235}U/{sup 238}U for short transient signals of only 15 s related to 10 to 200 pg of uranium. The detection limit (at the 3 sigma level) was ∼ 350 ag for the {sup 235}U isotope, meaning that {sup 235}U/{sup 238}U isotope ratios in natural uranium particles of ∼ 220 nm diameter can be measured. We also showed that the local contamination resulting from the side deposition of ablation debris at ∼ 100 μm from the ablation crater represented only a small percentage of the initial uranium signal of the ablated particle. Despite the use of single collector ICP-MS, we were able to demonstrate that fs-LA-ICP-MS is a promising alternative technique for determining uranium isotopic composition in particle analysis. - Highlights: • An infrared femtosecond laser ablation device coupled to an ICP-MS is used. • The isotopic composition of micrometer-size U particles is measured. • Results are in good agreement with the ones obtained by other relevant techniques. • Detection limit is 350 attograms for the {sup 235}U isotope • {sup 235}U/{sup 238}U ratios can be measured in 220 nm diameter natural uranium particles.

  1. Characterization of uranium bearing material using x-ray fluorescence and direct gamma-rays measurement techniques

    Energy Technology Data Exchange (ETDEWEB)

    Mujaini, M., E-mail: madihah@uniten.edu.my; Chankow, N. [Faculty of Engineering, Chulalongkorn University Phyathai Rd., Wang Mai, Patumwan, Bangkok 10330 (Thailand); Yusoff, M. Z.; Hamid, N. A. [College of Engineering, Universiti Tenaga Nasional 43000 Kajang, Selangor (Malaysia)

    2016-01-22

    Uranium ore can be easily detected due to various gamma-ray energies emitted from uranium daughters particularly from {sup 238}U daughters such as {sup 214}Bi, {sup 214}Pb and {sup 226}Ra. After uranium is extracted from uranium ore, only low energy gamma-rays emitted from {sup 235}U may be detected if the detector is placed in close contact to the specimen. In this research, identification and characterization of uranium bearing materials is experimentally investigated using direct measurement of gamma-rays from {sup 235}U in combination with the x-ray fluorescence (XRF) technique. Measurement of gamma-rays can be conducted by using high purity germanium (HPGe) detector or cadmium telluride (CdTe) detector while a {sup 57}Coradioisotope-excited XRF spectrometer using CdTe detector is used for elemental analysis. The proposed technique was tested with various uranium bearing specimens containing natural, depleted and enriched uranium in both metallic and powder forms.

  2. Cogenetic late Pleistocene rhyolite and cumulate diorites from Augustine Volcano revealed by SIMS 238U-230Th dating of zircon, and implications for silicic magma generation by extraction from mush

    Science.gov (United States)

    Coombs, Michelle L.; Vazquez, Jorge A.

    2014-12-01

    Volcano, a frequently active andesitic island stratocone, erupted a late Pleistocene rhyolite pumice fall that is temporally linked through zircon geochronology to cumulate dioritic blocks brought to the surface in Augustine's 2006 eruption. Zircon from the rhyolite yield a 238U-230Th age of ˜25 ka for their unpolished rims, and their interiors yield a bimodal age populations at ˜26 ka and a minority at ˜41 ka. Zircon from dioritic blocks, ripped from Augustine's shallow magmatic plumbing system and ejected during the 2006 eruption, have interiors defining a ˜26 ka age population that is indistinguishable from that for the rhyolite; unpolished rims on the dioritic zircon are dominantly younger (≤12 ka) indicating subsequent crystallization. Zircon from rhyolite and diorite overlap in U, Hf, Ti, and REE concentrations although diorites also contain a second population of high-U, high temperature grains. Andesites that brought dioritic blocks to the surface in 2006 contain zircon with young (≤9 ka) rims and a scattering of older ages, but few zircon that crystallized during the 26 ka interval. Both the Pleistocene-age rhyolite and the 2006 dioritic inclusions plot along a whole-rock compositional trend distinct from mid-Holocene-present andesites and dacites, and the diorites, rhyolite, and two early Holocene dacites define linear unmixing trends often oblique to the main andesite array and consistent with melt (rhyolite) extraction from a mush (dacites), leaving behind a cumulate amphibole-bearing residue (diorites). Rare zircon antecrysts up to ˜300 ka from all rock types indicate that a Quaternary center has been present longer than preserved surficial deposits.

  3. 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)

  4. SFR site investigation. Bedrock Hydrogeochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Nilsson, Ann-Chatrin [Geosigma AB, Uppsala (Sweden); Tullborg, Eva-Lena [Terralogica AB, Graabo (Sweden); Smellie, John [Conterra AB, Uppsala (Sweden); Gimeno, Maria J.; Gomez, Javier B.; Auque, Luis F. [Univ. of Zaragoza, Zaragoza (Spain); Sandstroem, Bjoern [WSP Sverige AB, Goeteborg (Sweden); Pedersen, Karsten [Micans AB, Moelnlycke (Sweden)

    2011-11-15

    There are plans that the final repository for low and intermediate level radioactive waste, SFR, located about 150 km north of Stockholm, will be extended. Geoscientific studies to define and characterise a suitable bedrock volume for the extended repository have been carried out from 2007 to 2011, and have included the drilling and evaluation of seven new core drilled and four percussion boreholes. These new data, together with existing data extending back to 1985, have been interpreted and modelled in order to provide the necessary information for safety assessment and repository design. This report presents the final hydrogeochemical site description for the SFR site, and will constitute a background report for the integrated site description (the SFR Site Descriptive Model version 1.0) together with corresponding reports from the geological and hydrogeological disciplines. Most of the hydrogeochemical data from the field investigations consist of major ions and isotopes together with sporadic gas, microbe and measured redox data. Despite the close proximity of the Forsmark site, few data from this source are of relevance because of the shallow nature of the SFR site, the fact that SFR is located beneath the Baltic Sea and also the drawdown/upconing impacts of its construction on the hydrogeochemistry. This artificially imposed dynamic flow system is naturally more prevalent along major deformation fracture zones of higher transmissivity, whilst lower transmissive fractures together with the less transmissive bedrock masses between major deformation zones, still retain some evidence of the natural groundwater mixing patterns established prior to the SFR construction. The groundwaters in the SFR dataset cover a depth down to -250 m.a.s.l. with single sampling locations at -300 and -400 m.a.s.l. and represent a relatively limited salinity range (1,500 to 5,500 mg/L chloride). However, the {delta}{sup 18}O values show a wide variation (-15.5 to -7.5 per mille V

  5. Standard test method for analysis of total and isotopic uranium and total thorium in soils by inductively coupled plasma-mass spectrometry

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 This test method covers the measurement of total uranium (U) and thorium (Th) concentrations in soils, as well as the determination of the isotopic weight percentages of 234U, 235U, 236U, and 238U, thereby allowing for the calculation of individual isotopic uranium activity or total uranium activity. This inductively coupled plasma-mass spectroscopy (ICP-MS) method is intended as an alternative analysis to methods such as alpha spectroscopy or thermal ionization mass spectroscopy (TIMS). Also, while this test method covers only those isotopes listed above, the instrumental technique may be expanded to cover other long-lived radioisotopes since the preparation technique includes the preconcentration of the actinide series of elements. The resultant sample volume can be further reduced for introduction into the ICP-MS via an electrothermal vaporization (ETV) unit or other sample introduction device, even though the standard peristaltic pump introduction is applied for this test method. The sample preparatio...

  6. Study of the uranium availability through the research method Th/U

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, Zahily Herrero; Santos Junior, Jose Araujo dos; Amaral, Romilton dos Santos; Santos, Josineide Marques do Nascimento; Damascena, Kennedy Francys Rodrigues; Medeiros, Nilson Vicente da Silva; Maciel Neto, Jose de Almeida, E-mail: zahily1985@gmail.com, E-mail: jaraujo@ufpe.br, E-mail: romilton@ufpe.br, E-mail: neideden@hotmail.com, E-mail: kennedy.eng.ambiental@gmail.com, E-mail: nvsmedeiros@gmail.com, E-mail: profjosemaciel@gmail.com [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Centro de Tecnologia e Geociencias. Departamento de Energia Nuclear; Alvarez, Juan Reinaldo Estevez, E-mail: jestevez@ceaden.cu [Centro de Aplicaciones Tecnologicas y Desarrollo Nuclear (CEADEN), Havana (Cuba); Silva, Alberto Antonio da, E-mail: alberto.silva@barreiros.ifpe.edu.br [Instituto Federal de Educacao, Ciencia e Tecnologia de Pernambuco (IFPE), Barreiros, PE (Brazil)

    2015-07-01

    The uranium and thorium, precursors of the main natural radioactive series, have different concentrations in the Earth's crust. The ratio Th/U has been used as an indicator of oxidizing and reducing conditions, whose factors suggest availability of uranium to displacement in the environment and incorporations in different matrices. This parameter become essential to determine possible conditions of availability by the chemical form and incorporation in the food chain. The state of Paraiba, in northeastern Brazil, has a uranium deposits located in Sao Jose de Espinharas, where there are agricultural practices in areas surrounding the deposit of natural uranium. The Environmental Monitoring Program and Radioecological, making it an area that offers all the features for research mobility of uranium, chemical form and availability of incorporation, in addition to understanding the kinetics and transport of this natural radionuclide in the environment. Soil samples were collected from agricultural areas, close to the uraniferous occurrences where the samples were analyzed in the Laboratorio de Radioecologia e Controle Ambiental (LARCA) of the Departamento de Energia Nuclear at the Universidade Federal de Pernambuco (UFPE) by High Resolution Gamma Spectrometry, obtaining the experimental activities of {sup 238}U and {sup 232}Th using indirect gamma measures. The obtained findings show that the ratio Th/U varied from 0.11 to 1.33, with an average of 0.69. (author)

  7. Distribution of uranium in marine sediments; Distribucion de uranio en sedimentos marinos

    Energy Technology Data Exchange (ETDEWEB)

    Ordonez R, E.; Ramirez T, J.J.; Lopez M, J.; Aspiazu, J. [ININ, 52750 La Marquesa, Estado de Mexico (Mexico); Ruiz F, A.C. [U. Academica Mazatlan, ICML, UNAM (Mexico); Valero C, N. [CONALEP, 52000 Lerma, Estado de Mexico (Mexico)

    2008-07-01

    The marine sediments obtained by means of a sampling nucleus in the Gulf of Tehuantepec, Mexico, they have been object of crystallographic and morphological characterization. The PIXE analysis of some samples in study is shown. The normal methodology to carry out the alpha spectroscopy indicates that the sample should be dissolved, but due to the nature of the marine sediments, it thinks about the necessity to make a fractional separation of the sample components. In each stratum of the profile it separates the organic part and the mineral to recover the uranium. It was observed that in the organic phase, the uranium is in two oxidation states (IV and Vl), being necessary the radiochemical separation with a liquid/liquid column chromatographic that uses the di-2-ethyl hexyl phosphoric acid as stationary phase. The uranium compounds extracts are electrodeposited in fine layers on stainless steel disks to carry out the analysis by alpha spectroscopy. The spectroscopic analysis of the uranium indicates us that for each stratum one has a difference marked in the quotient of activities of {sup 234}U/{sup 238}U that depends on the nature of the studied fraction. These results give us a clear idea about how it is presented the effect of the uranium migration and other radioelements in the biosphere, with what we can determine which are the conditions in that these have their maximum mobility and to know their diffusion patterns in the different media studied. (Author)

  8. 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)

  9. Flow Structure in a Bedrock Canyon (Invited)

    Science.gov (United States)

    Venditti, J. G.; Rennie, C. D.; Church, M. A.; Bomhof, J.; Lin, M.

    2013-12-01

    Bedrock canyon incision is widely recognized as setting the pace of landscape evolution. A variety of models link flow and sediment transport processes to the bedrock canyon incision rate. The model components that represent sediment transport processes are quite well developed in some models. In contrast, the model components that represent fluid flow remain rudimentary. Part of the reason is that there have been relatively few observations of flow structure in a bedrock canyon. Here, we present observations of flow obtained using an array of three acoustic Doppler current profilers during a 524 km long continuous centerline traverse of the Fraser River, British Columbia, Canada as it passes through a series of bedrock canyons. Through this portion of the river, the channel alternates between gravel-bedded reaches that are deeply incised into semi-consolidated glacial deposits and solid bedrock-bound reaches. We present observations of flow through 41 bedrock bound reaches of the river, derived from our centerline traverses and more detailed three-dimensional mapping of the flow structure in 2 canyons. Our observations suggest that flow in the most well-defined canyons (deep, laterally constrained, completely bedrock bound) is far more complex than that in a simple prismatic channel. As flow enters the canyon, a high velocity core plunges from the surface to the bed, causing a velocity inversion (high velocities at the bed and low velocities at the surface). This plunging flow then upwells along the canyon wall, resulting in a three-dimensional flow with counter-rotating, along-stream eddies that diverge near the bed. We observe centerline ridges along the canyon floors that result from the divergence and large-scale surface boils caused by the upwelling. This flow structure causes deep scour in the bedrock channel floor, and ensures the base of the canyon walls are swept of debris that otherwise may be deposited due to lower shear stresses abutting the walls. The

  10. Structure of Flow in a Bedrock Canyon

    Science.gov (United States)

    Venditti, J. G.; Rennie, C. D.; Church, M. A.; Bomhof, J.; Lin, M.

    2012-12-01

    Bedrock canyon incision is widely recognized as setting the pace of landscape evolution. A variety of models link flow and sediment transport processes to the bedrock canyon incision rate. The model components that represent sediment transport processes are quite well developed in some models. In contrast, the model components that represent fluid flow remain rudimentary. Part of the reason is that there have been relatively few observations of flow structure in a bedrock canyon. Here, we present observations of flow obtained using an array of three acoustic Doppler current profilers during a 524 km long continuous centerline traverse of the Fraser River, British Columbia, Canada as it passes through a series of bedrock canyons. Through this portion of the river, the channel alternates between gravel-bedded reaches that are deeply incised into semi-consolidated glacial deposits and solid bedrock-bound reaches. We present observations of flow through 41 bedrock bound reaches of the river, derived from our centerline traverses and more detailed three-dimensional mapping of the flow structure in 2 canyons. Our observations suggest that flow in the most well-defined canyons (deep, laterally constrained, completely bedrock bound) is far more complex than that in a simple prismatic channel. As flow enters the canyon, a high velocity core plunges from the surface to the bed, causing a velocity inversion (high velocities at the bed and low velocities at the surface). This plunging flow then upwells along the canyon wall, resulting in a three-dimensional flow with counter-rotating, along-stream eddies that diverge near the bed. We observe centerline ridges along the canyon floors that result from the divergence and large-scale surface boils caused by the upwelling. This flow structure causes deep scour in the bedrock channel floor, and ensures the base of the canyon walls are swept of debris that otherwise may be deposited due to lower shear stresses abutting the walls. The

  11. {sup 230}Th/U-dating of a late Holocene low uranium speleothem from Cuba

    Energy Technology Data Exchange (ETDEWEB)

    Fensterer, Claudia; Mangini, Augusta [Forschungsstelle Radiometrie, Heidelberg Academy of Sciences, Im Neuenheimer Feld 229, 69120 Heidelberg (Germany); Scholz, Denis; Hoffmann, Derik [School of Geographical Sciences, University of Bristol, University Road, BS8 1SS, Bristol (United Kingdom); Pajon, Jesus M, E-mail: Claudia.Fensterer@iup.uni-heidelberg.d [Department of Archaeology, Cuban Institute of Anthropology, Amargura No. 203, e/n Habana y Aguiar, Ciudad de La Habana, CP: 10 100 (Cuba)

    2010-03-15

    We present 22 U-series ages for a stalagmite from north-western Cuba based on multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) and thermal ionisation mass spectrometry (TIMS). Our results reveal that the stalagmite continuously grew within the last {approx}1400a. Low uranium content of the sample and thus, extremely low {sup 230}Th concentrations limit the precision and accuracy of {sup 230}Th/U-dating by TIMS. Samples measured by MC-ICPMS show a high variability of {sup 232}Th content along the growth axis with some sections significantly affected by initial {sup 230}Th from a detrital phase. An a-priori bulk earth ratio for ({sup 238}U/{sup 232}Th) cannot be used to accurately account for this initial {sup 230}Th. Using an age model based on the {sup 230}Th/U ages determined on samples with low or negligible {sup 232}Th concentration, we find that the ({sup 238}U/{sup 232}Th) activity ratio of the detrital phase is an order of magnitude larger than the bulk earth value, indicating the importance of an accurately determined correction factor.

  12. Migration behavior of naturally occurring radionuclides at the Nopal I uranium deposit, Chihuahua, Mexico

    Science.gov (United States)

    Prikryl, James D.; Pickett, David A.; Murphy, William M.; Pearcy, English C.

    1997-04-01

    Oxidation of pyrite at the Nopal I uranium deposit, Peña Blanca district, Chihuahua, Mexico has resulted in the formation of Fe-oxides/hydroxides. Anomalous U concentrations (i.e. several hundred to several thousand ppm) measured in goethite, hematite, and amorphous Fe-oxyhydroxides in a major fracture that crosscuts the deposit and the absence of U minerals in the fracture suggest that U was retained during secondary mineral growth or sorbed on mineral surfaces. Mobilization and transport of U away from the deposit is suggested by decreasing U concentrations in fracture-infilling materials and in goethite and hematite with distance from the deposit. Greater than unity {234U}/{238U} activity ratios measured in fracture-infilling materials indicate relatively recent ( < 1 Ma) U uptake from fluids that carried excess 234U. Systematic decreases in {234U}/{238U} activity ratios of fracture materials with distance from the deposit suggest a multistage mobilization process, such as remobilization of U from 234U-enriched infill minerals or differential or diminished transport of U-bearing solutions containing excess 234U.

  13. Detection and analysis of the microdistribution of uranium in the gills of freshwater Corbicula fluminea by SIMS technique

    Energy Technology Data Exchange (ETDEWEB)

    Tessier, C. [IRSN, Direction de la RadioProtection de l' Homme, Service de Dosimetrie Interne, Laboratoire de RadioChimie, IRSN, BP 17, F-92262 Fontenay aux Roses Cedex (France)], E-mail: christine.tessier@irsn.fr; Suhard, D. [IRSN, Direction de la RadioProtection de l' Homme, Service de Dosimetrie Interne, Laboratoire de RadioChimie, IRSN, BP 17, F-92262 Fontenay aux Roses Cedex (France); Simon, O.; Floriani, M. [IRSN, Direction de l' Environnement et de l' Intervention, Service d' Etude du Comportement des Radionucleides dans les ecosystemes, Laboratoire de Radioecologie et d' ecotoxicologie, IRSN, BP F6 Cadarache (France); Rebiere, F.; Jourdain, J.-R. [IRSN, Direction de la RadioProtection de l' Homme, Service de Dosimetrie Interne, Laboratoire de RadioChimie, IRSN, BP 17, F-92262 Fontenay aux Roses Cedex (France)

    2009-06-01

    The microdistribution of uranium in the gills of freshwater bivalve Corbicula fluminea following chronic direct exposure to this radioelement has been investigated using the SIMS technique. Different exposure levels and exposure durations have been studied. The SIMS mass spectra and {sup 238}U{sup +} ion images produced with a SIMS CAMECA 4F-E7 show an U accumulation with the lower aqueous U concentration (20 {mu}g/L) and the influence of the exposure levels on the bioaccumulation capacities. Furthermore, the ionic images display a heterogeneous distribution of uranium within the gill structure whatever the exposure conditions are. This study, in keeping with the ENVIRHOM French research program, was led to the conclusion that ion microscopy is an appropriate analytical method for trace elements and can give elemental cartography in a biological tissue section.

  14. Determination of Depleted Uranium in Environmental Bio-monitor Samples and Soil from Target sites in Western Balkan Region

    Science.gov (United States)

    Sahoo, Sarata K.; Enomoto, Hiroko; Tokonami, Shinji; Ishikawa, Tetsuo; Ujić, Predrag; Čeliković, Igor; Žunić, Zora S.

    2008-08-01

    Lichen and Moss are widely used to assess the atmospheric pollution by heavy metals and radionuclides. In this paper, we report results of uranium and its isotope ratios using mass spectrometric measurements (followed by chemical separation procedure) for mosses, lichens and soil samples from a depleted uranium (DU) target site in western Balkan region. Samples were collected in 2003 from Han Pijesak (Republika Srpska in Bosnia and Hercegovina). Inductively coupled plasma mass spectrometry (ICP-MS) measurements show the presence of high concentration of uranium in some samples. Concentration of uranium in moss samples ranged from 5.2-755.43 Bq/Kg. We have determined 235U/238U isotope ratio using thermal ionization mass spectrometry (TIMS) from the samples with high uranium content and the ratios are in the range of 0.002097-0.002380. TIMS measurement confirms presence of DU in some samples. However, we have not noticed any traces of DU in samples containing lesser amount of uranium or from any samples from the living environment of same area.

  15. Energy Dependence of Fission Product Yields from 235U, 238U and 239Pu for Incident Neutron Energies Between 0.5 and 14.8 MeV

    Science.gov (United States)

    Gooden, M. E.; Arnold, C. W.; Becker, J. A.; Bhatia, C.; Bhike, M.; Bond, E. M.; Bredeweg, T. A.; Fallin, B.; Fowler, M. M.; Howell, C. R.; Kelley, J. H.; Krishichayan; Macri, R.; Rusev, G.; Ryan, C.; Sheets, S. A.; Stoyer, M. A.; Tonchev, A. P.; Tornow, W.; Vieira, D. J.; Wilhelmy, J. B.

    2016-01-01

    Fission Product Yields (FPY) have historically been one of the most observable features of the fission process. They are known to have strong variations that are dependent on the fissioning species, the excitation energy, and the angular momentum of the compound system. However, consistent and systematic studies of the variation of these FPY with energy have proved challenging. This is caused primarily by the nature of the experiments that have traditionally relied on radiochemical procedures to isolate specific fission products. Although radiochemical procedures exist that can isolate all products, each element presents specific challenges and introduces varying degrees of systematic errors that can make inter-comparison of FPY uncertain. Although of high importance in fields such as nuclear forensics and Stockpile Stewardship, accurate information about the energy dependence of neutron induced FPY are sparse, due primarily to the lack of suitable monoenergetic neutron sources. There is a clear need for improved data, and to address this issue, a collaboration was formed between Los Alamos National Laboratory (LANL), Lawrence Livermore National Laboratory (LLNL) and the Triangle Universities Nuclear Laboratory (TUNL) to measure the energy dependence of FPY for 235U, 238U and 239Pu. The measurements have been performed at TUNL, using a 10 MV Tandem Van de Graaff accelerator to produce monoenergetic neutrons at energies between 0.6 MeV to 14.8 MeV through a variety of reactions. The measurements have utilized a dual-fission chamber, with thin (10-100 μg/cm2) reference foils of similar material to a thick (100-400 mg) activation target held in the center between the chambers. This method allows for the accurate determination of the number of fissions that occurred in the thick target without requiring knowledge of the fission cross section or neutron fluence on target. Following activation, the thick target was removed from the dual-fission chamber and gamma

  16. GeologicBedrock100k Dikes

    Data.gov (United States)

    Vermont Center for Geographic Information — The bedrock geology was last mapped at a statewide scale 50 years ago at a scale of 1:250,000 (Doll and others, 1961). The 1961 map was compiled from 1:62,500-scale...

  17. Distribution and potential health risk of groundwater uranium in Korea.

    Science.gov (United States)

    Shin, Woosik; Oh, Jungsun; Choung, Sungwook; Cho, Byong-Wook; Lee, Kwang-Sik; Yun, Uk; Woo, Nam-Chil; Kim, Hyun Koo

    2016-11-01

    Chronic exposure even to extremely low specific radioactivity of natural uranium in groundwater results in kidney problems and potential toxicity in bones. This study was conducted to assess the potential health risk via intake of the groundwater containing uranium, based on the determination of the uranium occurrence in groundwater. The groundwater was investigated from a total of 4140 wells in Korea. Most of the groundwater samples showed neutral pH and (sub-)oxic condition that was influenced by the mixing with shallow groundwater due to long-screened (open) wells. High uranium contents exceeding the WHO guideline level of 30 μg L(-1) were observed in the 160 wells located mainly in the plutonic bedrock regions. The statistical analysis suggested that the uranium component was present in groundwater by desorption and re-dissolution processes. Predominant uranium phases were estimated to uranyl carbonates under the Korean groundwater circumstances. These mobile forms of uranium and oxic condition facilitate the increase of potential health risk downgradient. In particular, long-term intake of groundwater containing >200 μg U L(-1) may induce internal exposure to radiation as well as the effects of chemical toxicity. These high uranium concentrations were found in twenty four sampling wells of rural areas in this study, and they were mainly used for drinking. Therefore, the high-level uranium wells and neighboring areas must be properly managed and monitored to reduce the exposure risk for the residents by drinking groundwater.

  18. Preparation, characterization and certification of uranium isotope reference materials; Preparacao, Caracterizacao e certificacao de materiais de referencia isotopicos de uranio

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira Junior, Olivio Pereira de

    2006-07-01

    This work describes the preparation, characterization and certification of a set of uranium isotope reference materials ranging from 0.5 to 20.0 % of {sup 235}U in mass. The most important concepts of metrology in chemical measurements were applied so that the certified quantities in these materials could be directly traceable to the International System of Units (SI). As a consequence of this approach, these materials can be used in the instruments calibration, estimation of measurement uncertainty, method validation, assessment of performance of analysts, quality control routines and interlaboratory comparison programmes. The most advanced methods and techniques in mass spectrometry, that is, gas source mass spectrometry (GSMS), thermal ionisation mass spectrometry (TIMS) and inductively coupled plasma mass spectrometry (ICPMS) were investigated to identify which are the dominant components in the uncertainty and to quantify its contribution to the final value of the measurement uncertainty of the isotopic ratio. The results obtained were then compared to verify which are the methods and techniques associated to the lowest measurement uncertainty values. The isotope amount ratio n({sup 235}U)/n({sup 238}U) was certified in the materials produced to expanded uncertainties ranging from 0.02 to 0.10 % and the ratios n({sup 234}U)/n({sup 238}U) and n({sup 236}U)/n({sup 238}U), to uncertainties ranging from 0.03 to 2.20 %. These values fully comply to the requirements of the isotopic characterization of nuclear fuel as well as the analysis of environmental samples for nuclear safeguards. (author)

  19. Assessment of radiation exposure around abandoned uranium mining area of Stara planina Mt., Serbia

    Directory of Open Access Journals (Sweden)

    Tanić Milan N.

    2014-01-01

    Full Text Available The aim of this work was to estimate the health and radiation hazard due to external irradiation from terrestrial radionuclides in the Stara planina Mt. region, which is important because of past uranium mining activities on the mountain. Soil samples were collected inside the flotation processing facilities, their surroundings and more distant locations, i.e. from areas considered certainly affected, potentially affected, and unaffected by former mining and uranium ore processing activities. The radiological and health risk assessments were done by calculating the six main parameters, based on the activity concentration of 238U, 232Th, and 40K in soil samples as determined by gamma-ray spectrometry. Increased values of the risk parameters were observed only for sites where uranium ore was processed, while the location surrounding these compounds showed values that are usual for this mountain or slightly above them. Calculations of the risk parameters for the background area showed no radiation risk for the local and seasonal population. The presence of U and Th was detected in all water samples from creeks surrounding the facilities, but only in the water from the facility drainage pipe did their concentration exceed the limits given for the uranium content in drinking water. In conclusion, the results obtained in this study fall within the range of values in similar studies conducted worldwide and are below the values which can cause a significant radiation hazard. [Projekat Ministarstva nauke Republike Srbije, br. III43009 i br. III41005

  20. Radionuclide migration at the Koongarra uranium deposit, Northern Australia Lessons from the Alligator Rivers analogue project

    Science.gov (United States)

    Payne, Timothy E.; Airey, Peter L.

    The Koongarra uranium deposit in Northern Australia provides a ‘natural analogue’ for processes that are of relevance for assessing the safety of radioactive waste disposal. In an international project extending over two decades, the Koongarra ore body was studied to increase the understanding of radionuclide migration and retention mechanisms that might occur in the vicinity of a geological repository. The research effort included extensive characterisation of the geological, hydrological and geochemical conditions at the site. Patterns of the distribution of radionuclides (predominantly members of the 238U decay chain, but also the rare isotopes 239Pu, 99Tc and 129I) were studied in both solid and groundwater phases. The project included detailed studies of uranium adsorption on mineral surfaces, and of subsequent processes that may lead to long-term uranium immobilisation. Numerous models for uranium migration were developed during the project. This paper provides a comprehensive review of the research at Koongarra, and assesses the value of the site for integrating the results of a complex series of laboratory, modelling and field studies. The insights gained from this review of the Koongarra project may assist in maximising the potential scientific benefit of future natural analogue studies.

  1. Bedrock Geologic Map of the Hinesburg Quadrangle, Vermont

    Data.gov (United States)

    Vermont Center for Geographic Information — Digital Data from Thompson, P., Thompson, T.B., and Doolan, B., 2004, Bedrock Geology of the Hinesburg quadrangle, Vermont. The bedrock geologic map data at a scale...

  2. Behaviour of {sup 210}Po in fresh water ecosystem located in high rainfall area around proposed uranium mining site in India

    Energy Technology Data Exchange (ETDEWEB)

    Jha, S.K. [Environmental Radioactivity measurement Section, Health Physics Division, Bhabha Atomic Research Centre, Mumbai-400085 (India)

    2014-07-01

    Several naturally occurring alpha or beta emitting radionuclides such as {sup 238}U, {sup 226}Ra, {sup 210}Pb, {sup 228}Ra and others are frequently dissolved in water supplies and their concentrations vary over an extremely wide range, mainly depending upon the amount of radio elements present in bedrock and soil with which the water comes in contact. In Meghalaya, Kylleng-Pyndensohiong, Mawthabah (KP Mawthabah Domiasiat) in West Khasi Hills District and adjoining region receives highest rainfall, and is situated near a proposed uranium mineralization zone, therefore these regions can be considered as potential sources of naturally occurring radionuclides of uranium series to the biosphere via different media. The population of the region depends mainly on different surface water sources for drinking water and also for agricultural purposes. Under these conditions some Po can be allochthonous i.e. coming with rainwater as water supply comes from the naturally formed small storage basin between the rocks which accumulate rainwater. Apart from cultivation, the occupation of the local tribal people is production of wood charcoal. This leads to excess deforestation, escalating the erosion of soil exposing the uranium bearing rock at some places, may enhance the natural radioactivity levels in nearby water bodies. The physico chemical parameter, Fe, Mn, gross alpha and {sup 210}Po activities were estimated for radiological assessment of surface water quality and behavior of {sup 210}Po. The measurement of {sup 210}Po was carried out using the {sup 208}Po tracers. A tracer recovery of 85% was observed in the case of biological samples. Recovery in the range of 90% to 95% was observed in the case of water sample. The {sup 210}Po concentration ranged from 10 to 64 mBq L{sup -1}. The lowest concentrations of {sup 210}Po were detected in water samples from Wakhaji (10±0.03) and the highest concentration of {sup 210}Po was observed in the water bodies of Nongtynger (64±0

  3. 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.

  4. A ground radiometric study of uranium, thorium and potassium in Isparta, Turkey

    Directory of Open Access Journals (Sweden)

    Osman Uyanik

    2010-06-01

    Full Text Available The radioelement concentrations of uranium (238U, thorium (232Th and potassium (40K, as their radionuclides eU, eTh and K, of Cünür Hill in the city of Isparta (Turkey and its surroundings were measured using gamma-ray spectrometry with a NaI(Tl detector. The measurements were performed over an area of 2 km × 8 km around Cünür Hill, which forms part of the Isparta volcanic region that has a trachyandesitic composition, and which included the limestone outcrops east of Cünür. The results are mapped as combined radioelement concentrations. The radioelement concentrations of eU, eTh and K measured for Cünür Hill are high because of its trachyandesitic composition, while those measured in the limestone area were low, as would be expected.

  5. Levels of potassium, uranium, thorium and rate of radiogenic heat production in the bedrock adjacent to Camamu and Almada sedimentary basins, Bahia, Brazil; Teores de potassio, uranio, torio e taxa de producao de calor radiogenico no embasamento adjacente as bacias sedimentares de Camamu e Almada, Bahia, Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Sapucaia, Najara Santos; Barbosa, Johildo Salomao Figueiredo [Instituto de Geociencias, Universidade Federal da Bahia, Salvador, BA (Brazil); Argollo, Roberto Max de, E-mail: nss@cpgg.ufba.br, E-mail: johildo@cpgg.ufba.br, E-mail: robmax@ufba.br [Laboratorio de Fisica Nuclear Aplicada, Instituto de Fisica, Universidade Federal da Bahia, Salvador, BA (Brazil)

    2005-10-15

    The bedrock adjacent to Camamu and Almada sedimentary basins is characterized mainly by rocks of granulite and amphibolite facies, with archaean and paleoproterozoic ages, which belong to orogen Itabuna-Salvador-Curaca. The units in major proportion in this context are the metatonalites associated with basic and metamonzonites belonging to Itabuna belt. In smaller area occur the Teolandia granite and the Moenda granodiorite associated with the Ipiau band amphibolites, the charnockites and charnoenderbites of Jequie bloc, the neoproterozoic sienites and the mafic dikes. The K, U and Th contents of the rocks vary from 0,02 to 6,33% for K, from < 0,2 to 9,10 ppm for U and from < 0,4 to 64,38 ppm for Th. These contents are higher in the charnockites, Moenda granodiorite, Teolandia granite and sienites, intermediate in the metatonalites and metamonzonites and lower in the basic granulites. The heat production rates are higher in the lithologies where K, U and Th are also higher, varying from 0,58 to 5,57 {mu}W m{sup -3}. The coverage areas of such lithologies are, however, small compared with that of the metatonalitic granulites, metamonzonitic granulites and sienites where the rates vary from 0,10 to 1,44 {mu}W m{sup -3}, 0,23 to 5,55 {mu}W m{sup -3} and 0,60 to 2,24 {mu}W m{sup -3}, respectively. In this case, the heat production rates vary from 0,10 to 1,44 {mu}W m{sup -3}. The basic granulites have the smaller rates, from 0,06 to 0,36 {mu}W m-3. The observation of the lithologies in the margins of the two basins suggest that, in the bedrock under the younger sediments, may predominate the metatonalites, followed by the metamonzonites, with some significant participation of sienites in the Almada basin. In those lithologies, the volumetric heat production rates, with one standard deviation range, are 0,41 +- 0,30 {mu}W m{sup -3} for metatonalites, 0,71 +- 0,57 {mu}W m{sup -3} for metamonzonites and 1,20 +- 0,51 {mu}W m{sup -3} for sienites. (author)

  6. Image segmentation for uranium isotopic analysis by SIMS: Combined adaptive thresholding and marker controlled watershed approach

    Energy Technology Data Exchange (ETDEWEB)

    Willingham, David G.; Naes, Benjamin E.; Heasler, Patrick G.; Zimmer, Mindy M.; Barrett, Christopher A.; Addleman, Raymond S.

    2016-05-31

    A novel approach to particle identification and particle isotope ratio determination has been developed for nuclear safeguard applications. This particle search approach combines an adaptive thresholding algorithm and marker-controlled watershed segmentation (MCWS) transform, which improves the secondary ion mass spectrometry (SIMS) isotopic analysis of uranium containing particle populations for nuclear safeguards applications. The Niblack assisted MCWS approach (a.k.a. SEEKER) developed for this work has improved the identification of isotopically unique uranium particles under conditions that have historically presented significant challenges for SIMS image data processing techniques. Particles obtained from five NIST uranium certified reference materials (CRM U129A, U015, U150, U500 and U850) were successfully identified in regions of SIMS image data 1) where a high variability in image intensity existed, 2) where particles were touching or were in close proximity to one another and/or 3) where the magnitude of ion signal for a given region was count limited. Analysis of the isotopic distributions of uranium containing particles identified by SEEKER showed four distinct, accurately identified 235U enrichment distributions, corresponding to the NIST certified 235U/238U isotope ratios for CRM U129A/U015 (not statistically differentiated), U150, U500 and U850. Additionally, comparison of the minor uranium isotope (234U, 235U and 236U) atom percent values verified that, even in the absence of high precision isotope ratio measurements, SEEKER could be used to segment isotopically unique uranium particles from SIMS image data. Although demonstrated specifically for SIMS analysis of uranium containing particles for nuclear safeguards, SEEKER has application in addressing a broad set of image processing challenges.

  7. Bedrock hydrogeochemistry Forsmark. Site descriptive modelling SDM-Site Forsmark

    Energy Technology Data Exchange (ETDEWEB)

    Laaksoharju, Marcus (Geopoint AB, Sollentuna (Sweden)); Smellie, John (Conterra AB, Partille (Sweden)); Tullborg, Eva-Lena (Terralogica, Graabo (Sweden)); Gimeno, Maria (Univ. of Zaragoza, Zaragoza (Spain)); Hallbeck, Lotta (Microbial Analytics, Goeteborg (Sweden)); Molinero, Jorge (Amphos XXI Consulting S.L., Barcelona (Spain)); Waber, Nick (Univ. of Bern, Bern (Switzerland))

    2008-12-15

    generally a high confidence in the description and understanding of the current spatial distribution of groundwater composition, mainly due to the consistency between different analyses and modelling of the chemical data, but also due to the agreement with the hydrogeological understanding of the area. The existence of a near-surface redox reaction zone appears to be plausible, but this is still unclear from uncertainties in data interpretation. Nevertheless, the abundance of calcite suggests there is active buffering capacity on dilute groundwaters low in calcite. Furthermore, even though quantification of the bedrock buffering capacity is not yet achieved, general indications from the Forsmark area as a whole point to a bedrock which has a sufficiently large buffering capacity to maintain pH values in the range 7 to 8.5 and Eh values lower than -140 mV. One important remaining uncertainty concerns the increase in sulphide concentrations measured in the on-going monitoring programme. Initial drilling and pumping may have disturbed the system or may have facilitated sulphate reduction, but this issue remains to be resolved. The monitoring programme will also support the overall understanding of the long term behaviour of other groundwater parameters such as uranium, DOC (dissolved organic carbon) and tritium

  8. 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.

  9. Characterization of a hydraulically induced bedrock fracture

    OpenAIRE

    2014-01-01

    Hydraulic fracturing is a controversial practice because of concerns about environmental impacts due to its widespread use in recovering unconventional petroleum and natural gas deposits. However, water-only hydraulic fracturing has been used safely and successfully for many years to increase the permeability of aquifers used for drinking and irrigation water supply. This process extends and widens existing bedrock fractures, allowing groundwater storage to increase. Researchers have studied ...

  10. Fixation and mobilisation of uranium and its radioactive decay products in C-richwater sediments; Festlegung und Mobilisierung von Uran und seinen radioaktiven Zerfallsprodukten in kohlenstoffreichen Gewaessersedimenten

    Energy Technology Data Exchange (ETDEWEB)

    Nassour, Mohammad

    2014-05-27

    The main aim of this work was to investigate the extent of uranium and radium -fixation and mobilization at the interface of mining influenced surface water and sub-hydric soils, sediment and plant detritus. A freshwater ecosystem (stream channels in an alder swamp forest - Alno-Lemnetum with low residence time shallow ponds) developed directly below a mining site (Neuensalz) and influenced by uranium containing water served as investigation site for the identification of possible fixation and mobilization mechanisms. In addition, investigations were carried out on sediments in a water reservoir downstream of the examined abandoned mining site. It could be shown, that radium concentrations of the examined surface water (2001 - 2004) are only slightly higher compared to the range of geogenic levels for German surface waters, and that its activity concentrations decreased along the investigated flow path. In contrast, uranium concentrations are well above geogenic levels and the concentration level stays high along the whole water pathway through the study area. The {sup 238}U:{sup 226}Ra ratio of the examined surface water from the spring to a pond outflow significantly increased. The uranium chain activity concentrations in the sediments determined in this study partly exceeded considerably the regional geogenic level. For the sediment water the {sup 238}U:{sup 226}Ra ratio in the first part of the flow path is significantly shifted in favor of radium while in the second part the ratio is shifted in favor of uranium. There were indications that the dissolved uranium is transported in the form of soluble carbonate complexes. Radium however is rather fixed under dominantly oxidizing conditions along the mainly turbulent mixed shallow water pathway. The fixation of uranium and radium in the upper section of the pathway (direct below the spring) was found to be inorganically, whereas in the second part organic bonds are more indicated. The influence of allochthonous

  11. The Neutron Spectrum in a Uranium Tube

    Energy Technology Data Exchange (ETDEWEB)

    Johansson, E.; Jonsson, E.; Lindberg, M.; Mednis, J.

    1963-10-15

    A series of experimental and theoretical investigations on neutron spectra in lattice cells has been started at the reactor R1. This report gives the results from the first one of these cells - one with a tube of natural -uranium surrounded by heavy water. In the measurements the cell was placed in the central, vertical channel of the reactor. The neutron spectrum from a lead scatterer in the uranium tube - outer diameter 49.2 mm, inner diameter 28.3 mm - was measured with a fast chopper in the energy region 0.01 to 100 eV. Subsidiary measurements indicated that the spectrum in the beam from the lead piece corresponds to the spectrum of the angular flux integrated over all angles. This correspondence is important for the interpretation of the experimental data. The thermal part of the spectrum was found to deviate significantly from a Maxwellian. However, the deviation is not very large, and one could use a Maxwellian, at least to give a rough idea of the hardness of the spectrum. For the present tube the temperature of this Maxwellian was estimated as 90 to 100 deg C above the moderator temperature (33 deg C). In the joining region the rise of the spectrum towards the thermal part is slower than for the cell boundary spectrum, measured earlier. In the epithermal region the limited resolution of the chopper has affected the measurements at the energies of the uranium resonances. However, the shape of the spectrum on the flanks of the first resonance in {sup 238}U (6.68 eV) has been obtained accurately. In the theoretical treatment the THERMOS code with a free gas scattering model has been used. The energy region was 3.06 - 0.00025 eV. The agreement with the measurements is good for the thermal part - possibly the theoretical spectrum is a little softer than the experimental one. In the joining region the results from THERMOS are comparatively high - probably due to the scattering model used.

  12. Uranium industry in Canada

    Energy Technology Data Exchange (ETDEWEB)

    1983-01-01

    Current state of uranium industry in Canada has been considered. It is shown that in Canada, which is the major supplier of uranium, new methods of prospecting, mining and processing of uranium are developed and the old ones are improved. Owing to automation and mechanization a higher labour productivity in uranium ore mining is achieved. The uranium industry of Canada can satisfy the future demands in uranium but introduction of any new improvement will depend completely on the rate of nuclear power development.

  13. [Regularities of lateral distribution of uranium and thorium decay series radionuclides in the anthropogenically changed soils from the area of radium production waste storage].

    Science.gov (United States)

    Evseeva, T I; Belykh, E S; Maĭstrenko, T A; Geras'kin, S A; Taskaev, A I; Vakhrusheva, O M

    2012-01-01

    Cartographical investigations of the territory of radium production waste storage has shown some changes in lateral differentiation of radionuclides of uranium and thorium decay series to occur during 27 years (1981-2008). Those changes are caused mostly by flat denudation typical for fluvial terrace. At present radionuclides of uranium and thorium decay series are concentrated mostly in flood lands and relief depressions. At the same time, decrease in the radionuclide activity concentration in 0-20 cm soil layer is observed with changes in lateral distribution. Total stocks of 226Ra, 210Pb and 210Po within catena soils studied in the northern and southern parts of the waste storage decreased 3-6 times, 238U - 2 times, and did not significantly change in case of 232Th during 27 years. Nonetheless, most of the samples studied are referred to radioactive waste both according to Russian standards (SPORO-2002) and IAEA safety norms (IAEA, 2004).

  14. Standard test method for analysis of isotopic composition of uranium in nuclear-grade fuel material by quadrupole inductively coupled plasma-mass spectrometry

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2000-01-01

    1.1 This test method is applicable to the determination of the isotopic composition of uranium (U) in nuclear-grade fuel material. The following isotopic weight percentages are determined using a quadrupole inductively coupled plasma-mass spectrometer (Q-ICP-MS): 233U, 234U, 235U, 236U, and 238U. The analysis can be performed on various material matrices after acid dissolution and sample dilution into water or dilute nitric (HNO3) acid. These materials include: fuel product, uranium oxide, uranium oxide alloys, uranyl nitrate (UNH) crystals, and solutions. The sample preparation discussed in this test method focuses on fuel product material but may be used for uranium oxide or a uranium oxide alloy. Other preparation techniques may be used and some references are given. Purification of the uranium by anion-exchange extraction is not required for this test method, as it is required by other test methods such as radiochemistry and thermal ionization mass spectroscopy (TIMS). This test method is also described i...

  15. Uptake of radionuclides by a common reed (Phragmites australis (Cav.) Trin. ex Steud.) grown in the vicinity of the former uranium mine at Zirovski vrh

    Energy Technology Data Exchange (ETDEWEB)

    Cerne, Marko, E-mail: marko.cerne@ijs.s [Jozef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); Smodis, Borut, E-mail: borut.smodis@ijs.s [Jozef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); Strok, Marko, E-mail: marko.strok@ijs.s [Jozef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia)

    2011-04-15

    From uranium mining areas, in particular, the radionuclides are usually discharged to the environment during the mining and milling process. At the former uranium mine Zirovski vrh, Slovenia, mine waste and mill tailings were deposited at the Jazbec site and the Borst site, respectively. Plants grown in soils contaminated with the seepage waters from tailings may represent radiological concern if radionuclides from the uranium decay chain are transferred into the food chain. Uranium is usually accumulated in the roots and translocated to the shoots in limited amounts. Uranium plant accumulators are usually plants from Brassicaceae and Poaceae families. A common reed (Phragmites australis (Cav.) Trin. ex Steud.), a tall perennial grass, growing in a wetland habitats, accumulates metals in the above-ground parts. It may be used for phytoremediation of uranium-contaminated soils, because of high biomass production and high metal-accumulation potential. Preliminary results of radionuclide contents measured in such plants, growing on the deposit tailings are presented. A common reed, that was grown on the Borst tailings pile accumulated 8.6 {+-} 8 mBq/g dry weight (d.w.) and 2.4 {+-} 2 mBq/g dry weight (d.w.) of {sup 238}U in leaves and stems, respectively. In the paper, activity concentrations of other nuclides, i.e. {sup 226}Ra, {sup 210}Pb and {sup 40}K are also shown and discussed.

  16. 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.

  17. Determination of elemental impurities and U and O isotopic compositions with a view to identify the geographical and industrial origins of uranium ore concentrates

    Science.gov (United States)

    Salaun, A.; Hubert, A.; Pointurier, F.; Aupiais, J.; Pili, E.; Richon, P.; Fauré, A.; Diallo, S.

    2012-12-01

    First events of illicit trafficking of nuclear and radiological materials occurred 50 years ago. Nuclear forensics expertise are aiming at determining the use of seized material, its industrial history and provenance (geographical area, place of production or processing), at assisting in the identification and dismantling of illicit trafficking networks. This information is also valuable in the context of inspections of declared facilities to verify the consistency of operator's declaration. Several characteristics can be used to determine the origin of uranium ore concentrates such as trace elemental impurity patterns (Keegan et al., 2008 ; Varga et al., 2010a, 2010b) or uranium, oxygen and lead isotopic compositions (Tamborini et al., 2002a, 2002b ; Wallenius et al., 2006; Varga et al., 2009). We developed analytical procedures for measuring the isotopic compositions of uranium (234U/238U and 235U/238U) and oxygen (18O/16O) and levels of elemental impurities (e.g. REE, Th) from very small amounts of uranium ore concentrates (or yellow cakes). Micrometer particles and few milligrams of material are used for oxygen isotope measurements and REE determination, respectively. Reference materials were analyzed by mass spectrometry (TIMS, SF-ICP-MS and SIMS) to validate testing protocols. Finally, materials of unknown origin were analyzed to highlight significant differences and determine whether these differences allow identifying the origin of these ore concentrates. References: Keegan, E., et al. (2008). Applied Geochemistry 23, 765-777. Tamborini, G., et al. (2002a). Analytical Chemistry 74, 6098-6101. Tamborini, G., et al. (2002b). Microchimica Acta 139, 185-188. Varga, Z., et al. (2009). Analytical Chemistry 81, 8327-8334. Varga, Z., et al. (2010a). Talanta 80, 1744-1749. Varga, Z., et al. (2010b). Radiochimica Acta 98, 771-778 Wallenius, M., et al. (2006). Forensic Science International 156, 55-62.

  18. Sequential determination of natural ({sup 232}Th, {sup 238}U) and anthropogenic ({sup 137}Cs, {sup 90}Sr, {sup 241}Am, {sup 239+240}Pu) radionuclides in environmental matrix

    Energy Technology Data Exchange (ETDEWEB)

    Michel, H.; Levent, D.; Barci, V.; Barci-Funel, G.; Hurel, C. [Laboratoire de Radiochimie, Sciences Analytiques et Environnement (LRSAE), Universite de Nice Sophia-Antipolis 06108 Nice Cedex (France)

    2008-07-01

    A new sequential method for the determination of both natural (U, Th) and anthropogenic (Sr, Cs, Pu, Am) radionuclides has been developed for application to soil and sediment samples. The procedure was optimised using a reference sediment (IAEA-368) and reference soils (IAEA-375 and IAEA-326). Reference materials were first digested using acids (leaching), 'total' acids on hot plate, and acids in microwave in order to compare the different digestion technique. Then, the separation and purification were made by anion exchange resin and selective extraction chromatography: Transuranic (TRU) and Strontium (SR) resins. Natural and anthropogenic alpha radionuclides were separated by Uranium and Tetravalent Actinide (UTEVA) resin, considering different acid elution medium. Finally, alpha and gamma semiconductor spectrometer and liquid scintillation spectrometer were used to measure radionuclide activities. The results obtained for strontium-90, cesium-137, thorium-232, uranium- 238, plutonium-239+240 and americium-241 isotopes by the proposed method for the reference materials provided excellent agreement with the recommended values and good chemical recoveries. (authors)

  19. URANIUM-SERIES DISEQUILIBRIUM IN TUFF AND GRANITE:HYDROGEOLOGICAL IMPLICATIONS

    Energy Technology Data Exchange (ETDEWEB)

    M. Gasscoyne; N.H. Miller

    2000-10-27

    Uranium occurs naturally at trace levels in the major rock-forming minerals (quartz, feldspars, micas) in volcanic and plutonic rocks and is concentrated in accessory minerals (zircon, sphene, apatite). It may attain concentrations as high as 1000 ppm in the accessory minerals. Radiometric age determinations on zircon and sphene have shown that uranium migration from these minerals is generally negligible over prolonged periods of geologic time. Zircon grains separated from highly weathered igneous rocks have been found to retain most of their uranium. In contrast, the uranium fixed onto mineral grain boundaries or present in less-resistant minerals such as biotite or hornblende can be readily leached by groundwater. The ubiquitous presence of uranium in a rock makes it an ideal ''natural analogue'' for understanding the mobility of uranium at a potential site for nuclear fuel waste disposal and one that is easily overlooked in the search for suitable analogues for a disposal site. Several of the intermediate radionuclides in the decay series of the two long-lived isotopes of uranium ({sup 238}U and {sup 235}U) have half-lives greater than one year and are, therefore, of geological interest. In a sealed rock mass with no water-rock interactions, all intermediate radionuclides attain radioactive equilibrium with one another within a maximum 1-2 million years. Because rocks of the Yucca Mountain area and the Canadian Shield (both potential sites for nuclear waste disposal in the United States and Canadian programs, respectively) are considerably older, this condition (known as secular equilibrium) should exist in these rocks, and all daughter/parent radionuclide activity ratios should equal unity (1.000). If the ratios are found not to equal unity, then the rock has been disturbed, probably by groundwater transport of more soluble radionuclides into or away from the rock. How recently this migration has occurred can be determined from the half

  20. Radionuclides in waters and soil near the Lagoa Real uranium mine

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Susana Oliveira de; Freire, Fabinara Dantas, E-mail: sosouza@ufs.br [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil). Departamento de Fisica; Kozlowska, Beata; Walencik-Lata, Agata, E-mail: beata.kozlowska@us.edu.pl [University of Silesia, Institute of Physics, Katowice (Poland); Dias, Dario M., E-mail: engenheirodario@gmail.com [Secretaria Municipal de Meio Ambiente e Turismo, Andarai, BA (Brazil); Veiga, Artur Jose Pires, E-mail: tk1@ibest.com [Universidade Estadual do Sudoeste da Bahia (UESB), Itapetinga, BA (Brazil). Departamento de Ciencias Exatas e Tecnologicas

    2015-07-01

    Uranium mining generates fuel for the nuclear power plants and it is the main source of income for the region of Caetite-BA. However, Non-Governmental Organizations claim that mining pollutes the environment and jeopardizes human health and safety. Besides uranium, the ground contains significant concentrations of thorium and of all radionuclides of its family, such as radium isotopes. In this framework, we carried out an independent study analyzing the concentration of the radionuclides activities {sup 226,} {sup 228}Ra and {sup 234,238}U in water samples and radionuclides {sup 226}Ra, {sup 232}Th and {sup 40}K in soil samples using different techniques of nuclear spectrometry. The selection criteria for the collection points were their proximity to the uranium processing plant and to affluent rivers. The soil samples presented very low concentration of activity for radionuclides investigated, compared to the limits established of the exclusion, exemption and impartiality for radiation protection requirement given by the Regulator Position established by CNEN. The amount of radioisotopes appears consistent with a natural origin, thus it is not possible to state that the mining process in Caetite increases pollution or radiation exposure in a significant way. (author)

  1. 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.

  2. Uranium processing and properties

    CERN Document Server

    2013-01-01

    Covers a broad spectrum of topics and applications that deal with uranium processing and the properties of uranium Offers extensive coverage of both new and established practices for dealing with uranium supplies in nuclear engineering Promotes the documentation of the state-of-the-art processing techniques utilized for uranium and other specialty metals

  3. Distribution and transport of radionuclides in a boreal mire--assessing past, present and future accumulation of uranium, thorium and radium.

    Science.gov (United States)

    Lidman, Fredrik; Ramebäck, Henrik; Bengtsson, Åsa; Laudon, Hjalmar

    2013-07-01

    The spatial distribution of (238)U, (226)Ra, (40)K and the daughters of (232)Th, (228)Ra and (228)Th, were measured in a small mire in northern Sweden. High activity concentrations of (238)U and (232)Th (up to 41 Bq (238)U kg(-1)) were observed in parts of the mire with a historical or current inflow of groundwater from the surrounding till soils, but the activities declined rapidly further out in the mire. Near the outlet and in the central parts of the mire the activity concentrations were low, indicating that uranium and thorium are immobilized rapidly upon their entering the peat. The (226)Ra was found to be more mobile with high activity concentrations further out into the mire (up to 24 Bq kg(-1)), although the central parts and the area near the outlet of the mire still had low activity concentrations. Based on the fluxes to and from the mire, it was estimated that approximately 60-70% of the uranium and thorium entering the mire currently is retained within it. The current accumulation rates were found to be consistent with the historical accumulation, but possibly lower. Since much of the accumulation still is concentrated to the edges of the mire and the activities are low compared to other measurements of these radionuclides in peat, there are no indications that the mire will be saturated with respect to radionuclides like uranium, thorium and radium in the foreseen future. On the contrary, normal peat growth rates for the region suggest that the average activity concentrations of the peat currently may be decreasing, since peat growth may be faster than the accumulation of radionuclides. In order to assess the total potential for accumulation of radionuclides more thoroughly it would, however, be necessary to also investigate the behaviour of other organophilic elements like aluminium, which are likely to compete for binding sites on the organic material. Measurements of the redox potential and other redox indicators demonstrate that uranium possibly

  4. Airborne Plutonium and non-natural Uranium from the Fukushima DNPP found at 120 km distance a few days after reactor hydrogen explosions.

    Science.gov (United States)

    Shinonaga, Taeko; Steier, Peter; Lagos, Markus; Ohkura, Takehisa

    2014-04-01

    Plutonium (Pu) and non-natural uranium (U) originating from the Fukushima Daiichi Nuclear Power Plant (FDNPP) were identified in the atmosphere at 120 km distance from the FDNPP analyzing the ratio of number of atoms, following written as n(isotope)/n(isotope), of Pu and U. The n((240)Pu)/n((239)Pu), n((241)Pu)/n((239)Pu), n((234)U)/n((238)U), n((235)U)/n((238)U) and n((236)U)/n((238)U) in aerosol samples collected before and after the FDNPP incident were analyzed by accelerator mass spectrometry (AMS) and inductively coupled plasma mass spectrometry (ICPMS). The activity concentrations of (137)Cs and (134)Cs in the same samples were also analyzed by gamma spectrometry before the destructive analysis. Comparing the time series of analytical data on Pu and U obtained in this study with previously reported data on Pu, U, and radioactive Cs, we concluded that Pu and non-natural U from the FDNPP were transported in the atmosphere directly over a 120 km distance by aerosol and wind within a few days after the reactor hydrogen explosions. Effective dose of Pu were calculated using the data of Pu: (130 ± 21) nBq/m(3), obtained in this study. We found that the airborne Pu contributes only negligibly to the total dose at the time of the incident. However the analytical results show that the amount of Pu and non-natural U certainly increased in the environment after the incident.

  5. Fractal Character of China Bedrock Coastline

    Institute of Scientific and Technical Information of China (English)

    朱晓华

    2004-01-01

    Fractal theory was applied to a preliminary discussion of the fractal character and formation mechanism of the coastline of the bedrock coast of China on the basis of GIS (Geographical Information System). Some significant conclusions were drawn:(1) The fractal dimensions of the coastline and linear structures of Liaodong Peninsula are 1.0093 and 1.0246 respectively, those of Shandong Peninsula are 1.019 and 1.021 respectively, etc.(2) The fractal dimensions of coastlines of Liaodong Peninsula, Shandong Peninsula, Zhejiang and Fujian-Guangdong tend to increase with the spatial change from north to south.(3)The regional linear structures(including faults)control the basic trends and fractal dimensions of coastlines as a whole in the regions of the bedrock coast of China:the more the controlling effect of linear structures, the smaller the fractal dimensions of coastlines.(4)The substantial constituents of coast and biologic function both play an important role in affecting the fractal dimensions of coastlines of Liaodong Peninsula, Shandong Peninsula, Zhejiang, Fujian-Guangdong and Taiwan Island.

  6. An alternative procedure for uranium analysis in drinking water using AQUALIX columns: application to varied French bottled waters.

    Science.gov (United States)

    Bouvier-Capely, C; Bonthonneau, J P; Dadache, E; Rebière, F

    2014-01-01

    The general population is chronically exposed to uranium ((234)U, (235)U, and (238)U) and polonium ((210)Po) mainly through day-to-day food and beverage intake. The measurement of these naturally-occurring radionuclides in drinking water is important to assess their health impact. In this work the applicability of calix[6]arene-derivatives columns for uranium analysis in drinking water was investigated. A simple and effective method was proposed on a specific column called AQUALIX, for the separation and preconcentration of U from drinking water. This procedure is suitable for routine analysis and the analysis time is considerably shortened (around 4h) by combining the separation on AQUALIX with fast ICP-MS measurement. This new method was tested on different French bottled waters (still mineral water, sparkling mineral water, and spring water). Then, the case of simultaneous presence of uranium and polonium in water was considered due to interferences in alpha spectrometry measurement. A protocol was proposed using a first usual step of spontaneous deposition of polonium on silver disc in order to separate Po, followed by the uranium extraction on AQUALIX column before alpha spectrometry counting.

  7. Gamma-ray characterization of uranium-series nuclides and its application to the study of the Pena Blanca natural analogue site, Chihuahua, Mexico

    Science.gov (United States)

    Wong, Virgina

    Two natural analogue sites located in the Pena Blanca Uranium District, Chihuahua, Mexico were characterized for radionuclide mobility. Analogue I is used to assess the long-term behavior of uranium-series nuclides in a host rock and geochemical environment that is similar to the proposed high-level waste repository at Yucca Mountain, Nevada. Analogue II represents a former dump site to assess short-term radionuclide mobility. Gamma-ray spectroscopy analysis was used to measure radioactivity of the U-series nuclides. Samples analyzed from Analogue I consist of: (1) fracture-infillings associated with different alteration assemblages collected within and outside the breccia pipe from various levels of the deposit and (2) fracture-infillings collected along an east-west trending fracture which intersects the breccia pipe and extends into the host rock. Alteration mineralogy, established via X-ray diffraction analysis, consists of pure kaolinite, a mixture of Fe-oxyhydroxide (goethite, hematite) With inclusions of jarosite and alunite, and carbonates. Results from activity ratios of 230Th/238U versus 226Ra/230Th indicate that majority of the Fe-oxyhydroxides from the breccia zone show a slight disequilibrium with respect to Ra enrichment and U depletion. This observation is modeled as requiring a multiple-event history of U mobility. An amorphous Fe sample distal to the breccia zone shows similar behavior but to a greater extent. This extreme behavior is ascribed to initially low U content and greater late-stage U removal. Two Fe-oxyhydroxide samples from Within the breccia pipe also display multiple-event stages but exhibit both Ra and U leaching. This behavior is shared by Fe-oxyhydroxide samples collected inside and peripheral to the breccia zone from the east-west trending fracture. Finally, three samples, two Fe phase samples outside the breccia zone and a kaolinite inside the breccia zone, show Ra and U enrichment. Also, a distal Fe-oxyhydroxide sample from the

  8. Bioaccessibility of U, Th and Pb in particulate matter from an abandoned uranium mine

    Science.gov (United States)

    Millward, Geoffrey; Foulkes, Michael; Henderson, Sam; Blake, William

    2016-04-01

    Currently, there are approximately 150 uranium mines in Europe at various stages of either operation, development, decommissioning, restoration or abandonment (wise-uranium.com). The particulate matter comprising the mounds of waste rock and mill tailings poses a risk to human health through the inadvertent ingestion of particles contaminated with uranium and thorium, and their decay products, which exposes recipients to the dual toxicity of heavy elements and their radioactive emissions. We investigated the bioaccessibility of 238U, 232Th and 206,214,210Pb in particulate samples taken from a contaminated, abandoned uranium mine in South West England. Sampling included a mine shaft, dressing floor and waste heap, as well as soils from a field used for grazing. The contaminants were extracted using the in-vitro Unified Bioaccessibility Research Group of Europe Method (UBM) in order to mimic the digestion processes in the human stomach (STOM) and the combined stomach and gastrointestinal tract (STOM+INT). Analyses of concentrations of U, Th and Pb in the extracts were by ICP-MS and the activity concentrations of radionuclides were determined on the same particles, before and after extraction, using gamma spectroscopy. 'Total' concentrations of U, Th and Pb for all samples were in the range 57 to 16,200, 0.28 to 3.8 and 69 to 4750 mg kg-1, respectively. For U and Pb the concentrations in the STOM fraction were lower than the total and STOM+INT fractions were even lower. However, for Th the STOM+INT fractions were higher than the STOM due to the presence of Th carbonate species within the gastrointestinal fluid. Activity concentrations for 214Pb and 210Pb, including total, STOM and STOM+INT, were in the range 180 to <1 Bq g-1 for the dressing floor and waste heap and 18 to <1 Bq g-1 for the grazing land. Estimates of the bioaccessible fractions (BAFs) of 238U in the most contaminated samples were 39% and 8% in the STOM and STOM+INT, respectively, whereas the respective

  9. Localized bedrock aquifer distribution explains discharge from a headwater catchment

    Science.gov (United States)

    Kosugi, Ken'ichirou; Fujimoto, Masamitsu; Katsura, Shin'ya; Kato, Hiroyuki; Sando, Yoshiki; Mizuyama, Takahisa

    2011-07-01

    Understanding a discharge hydrograph is one of the leading interests in catchment hydrology. Recent research has provided credible information on the importance of bedrock groundwater on discharge hydrographs from headwater catchments. However, intensive monitoring of bedrock groundwater is rare in mountains with steep topography. Hence, how bedrock groundwater controls discharge from a steep headwater catchment is in dispute. In this study, we conducted long-term hydrological observations using densely located bedrock wells in a headwater catchment underlain by granitic bedrock. The catchment has steep topography affected by diastrophic activities. Results showed a fairly regionalized distribution of bedrock aquifers within a scale of tens of meters, consisting of upper, middle, and lower aquifers, instead of a gradual and continuous decline in water level from ridge to valley bottom. This was presumably attributable to the unique bedrock structure; fault lines developed in the watershed worked to form divides between the bedrock aquifers. Spatial expanse of each aquifer and the interaction among aquifers were key factors to explain gentle and considerable variations in the base flow discharge and triple-peak discharge responses of the observed hydrograph. A simple model was developed to simulate the discharge hydrograph, which computed each of the contributions from the soil mantle groundwater, from the lower aquifer, and from the middle aquifer to the discharge. The modeling results generally succeeded in reproducing the observed hydrograph. Thus, this study demonstrated that understanding regionalized bedrock aquifer distribution is pivotal for explaining discharge hydrograph from headwater catchments that have been affected by diastrophic activities.

  10. Spatial distribution of gamma radiation levels in surface soils from Jaduguda uranium mineralization zone, Jharkhand, India, using γ-ray spectrometry, and determination of outdoor dose to the population

    Directory of Open Access Journals (Sweden)

    Maharana Mandakini

    2010-01-01

    Full Text Available The concentrations of natural radionuclides in surface soil samples around selected villages of Jaduguda were investigated and compared with the radioactivity level in the region. Concentrations of 238 U, 232 Th, and 40 K were determined by a gamma ray spectrometer using the HPGe detector with 50% relative efficiency, and the radiation dose to the local population was estimated. The average estimated activity concentrations of 238 U, 232 Th, and 40 K in the surface soil were 53.8, 44.2 and 464.2 Bq kg -1 respectively. The average absorbed dose rate in the study area was estimated to be 72.5 nGy h-1, where as the annual effective dose to the population was 0.09 mSv y-1. A correlation analysis was made between measured dose rate and individual radionuclides, in order to delineate the contribution of the respective nuclides towards dose rate. The radio-elemental concentrations of uranium, thorium and potassium estimated for the soils, in the study area, indicated the enrichment of uranium series nuclide. The results of the present study were subsequently compared with international and national recommended values.

  11. Elemental hydrochemistry and hydro geochemistry of the uranium isotopes in Alter do Chao formation, Manaus (Amazon - Brazil); Hidroquimica elementar e dos isotopos de uranio em aguas subterraneas da Formacao Alter do Chao, Manaus (AM)

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Marcio Luiz da [Instituto Nacional de Pesquisas da Amazonia (INPA), Manaus, AM (Brazil). Coordenacao de Pesquisas]. E-mail: marciols@inpa.gov.br; Bonotto, Daniel Marcos [UNESP, Rio Claro, SP (Brazil). Inst. de Geociencias e Ciencias Exatas. Dept. de Petrologia e Metalogenia]. E-mail: dbonotto@rc.unesp.br

    2006-09-15

    The water exploitation at Manaus city, Amazonas State, Brazil, takes place from Negro River and tubular wells, being performed by a private company. This paper evaluates the hydrochemistry and geochemical behavior of uranium isotopes ({sup 238}U and {sup 234}U) in groundwaters from Manaus city, with the aim to characterize the contaminants or pollutants that possibly are affecting the quality of the underground hydrological resources, as well as to evaluate the potential use of the natural U-isotopes as hydrological tracers in the aquifer studied. The U-isotopes analysis allowed to determine {sup 234}U/{sup 238}U activity ratios of 1.2-4.4, and dissolved uranium concentration of 0.003-1.1 {mu}g.L{sup -1} (ppb). These results and those concerning the others parameters indicated that the waters are appropriate for human consumption, permitting to classify the hydrological system as acid-reducing, and to say that the waters leach minerals in strata containing low U content.(author)

  12. Investigation of Space and Energy Distributions of Neutrons Generated in Lead Target and Uranium Blanket of the Electronuclear System "Energy plus Transmutation" under Irradiation with Protons at 1.5 GeV

    CERN Document Server

    Zhuk, I V; Krivopustov, M I; Sosnin, A N; Chultem, D; Vestmaer, V; Tumendelger, T; Zaveryukha, O S; Pavlyuk, A B

    2002-01-01

    The work contains the results of space-energy distributions of neutrons in U/Pb assembly, consisting of extended lead target and the model of natural uranium blanket irradiated with relativistic protons at 1.5 GeV. The research is carried out in the framework of a series of experiments using the model of subcritical heterogeneous electronuclear system at the Laboratory of High Energies, JINR, Dubna ("Investigation of Physical Aspects of Electronuclear Method of Energy Production and Transmutation of Radioactive Waste Using Beams from JINR Synchrophasotron/Nuclotron" - project "Energy plus Transmutation"). The results of measurements and calculations of ^{235}U, ^{238}U and ^{232}Th fission rate distributions as well as threshold spectral indexes {\\bar\\sigma_f^{^{232}Th}}/{\\bar\\sigma_f^{^{235}U}} and {\\bar\\sigma_f^{^{238}U}}/{\\bar\\sigma_f^{^{235}U}} along the radius of the target and model uranium blanket are presented. The results of measurements and calculations of ^{234}U, ^{236}U and ^{237}Np fission rate ...

  13. Preliminary study of a radiological survey in an abandoned uranium mining area in Madagascar

    Science.gov (United States)

    N, Rabesiranana; M, Rasolonirina; F, Solonjara A.; Andriambololona., Raoelina; L, Mabit

    2010-05-01

    The region of Vinaninkarena located in central Madagascar (47°02'40"E, 19°57'17"S), is known to be a high natural radioactive area. Uranium ore was extracted in this region during the 1950s and the early 1960s. In the mid-1960s, mining activities were stopped and the site abandoned. In the meantime, the region, which used to be without any inhabitants, has recently been occupied by new settlers with presumed increase in exposure of the local population to natural ionizing radiation. In order to assess radiological risk, a survey to assess the soil natural radioactivity background was conducted during the year 2004. This study was implemented in the frame of the FADES Project SP99v1b_21 entitled: Assessment of the environmental pollution by multidisciplinary approach, and the International Atomic Energy Agency Technical Cooperation Project MAG 7002 entitled: Effects of air and water pollution on human health. Global Positioning System (GPS) was used to determine the geographical coordinates of the top soil samples (0-15cm) collected. The sampling was performed using a multi integrated scale approach to estimate the spatial variability of the parameters under investigation (U, Th and K) using geo-statistical approach. A total of 205 soil samples was collected in the study site (16 km2). After humidity correction, the samples were sealed in 100 cm3 cylindrical air-tight plastic containers and stored for more than 6 months to reach a secular equilibrium between parents and short-lived progeny (226Ra and progeny, 238U and 234Th). Measurements were performed using a high-resolution HPGe Gamma-detector with a 30% relative efficiency and an energy resolution of 1.8 keV at 1332.5 keV, allowing the determination of the uranium and thorium series and 40K. In case of secular equilibrium, a non-gamma-emitting radionuclide activity was deduced from its gamma emitting progeny. This was the case for 238U (from 234Th), 226Ra (from 214Pb and 214Bi) and 232Th (from 228Ac, 212Pb or

  14. Morphology Characterization of Uranium Particles From Laser Ablated Uranium Materials

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    In the study, metallic uranium and uranium dioxide material were ablated by laser beam in order to simulate the process of forming the uranium particles in pyrochemical process. The morphology characteristic of uranium particles and the surface of

  15. Natural fractionation of uranium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Noordmann, Janine

    2015-01-24

    The topic of this thesis was the investigation of U (n({sup 238}U) / n({sup 235}U)) isotope variations in nature with a focus on samples (1) that represent the continental crust and its weathering products (i.e. granites, shales and river water) (2) that represent products of hydrothermal alteration on mid-ocean ridges (i.e. altered basalts, carbonate veins and hydrothermal water) and (3) from restricted euxinic basins (i.e. from the water column and respective sediments). The overall goal was to explore the environmental conditions and unravel the mechanisms that fractionate the two most abundant U isotopes, n({sup 238}U) and n({sup 235}U), on Earth.

  16. Uranium Provinces in China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Three uranium provinces are recognized in China, the Southeast China uranium province, the Northeast China-lnner Mongolia uranium province and the Northwest China (Xinjiang) uranium province. The latter two promise good potential for uranium resources and are major exploration target areas in recent years. There are two major types of uranium deposits: the Phanerozoic hydrothermal type (vein type) and the Meso-Cenozoic sandstone type in different proportions in the three uranium provinces. The most important reason or prerequisite for the formation of these uranium provinces is that Precambrian uranium-enriched old basement or its broken parts (median massifs) exists or once existed in these regions, and underwent strong tectonomagmatic activation during Phanerozoic time. Uranium was mobilized from the old basement and migrated upwards to the upper structural level together with the acidic magma originating from anatexis and the primary fluids, which were then mixed with meteoric water and resulted in the formation of Phanerozoic hydrothermal uranium deposits under extensional tectonic environments. Erosion of uraniferous rocks and pre-existing uranium deposits during the Meso-Cenozoic brought about the removal of uranium into young sedimentary basins. When those basins were uplifted and slightly deformed by later tectonic activity, roll-type uranium deposits were formed as a result of redox in permeable sandstone strata.

  17. Uranium industry annual 1994

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-07-05

    The Uranium Industry Annual 1994 (UIA 1994) provides current statistical data on the US uranium industry`s activities relating to uranium raw materials and uranium marketing during that survey year. The UIA 1994 is prepared for use by the Congress, Federal and State agencies, the uranium and nuclear electric utility industries, and the public. It contains data for the 10-year period 1985 through 1994 as collected on the Form EIA-858, ``Uranium Industry Annual Survey.`` Data collected on the ``Uranium Industry Annual Survey`` (UIAS) provide a comprehensive statistical characterization of the industry`s activities for the survey year and also include some information about industry`s plans and commitments for the near-term future. Where aggregate data are presented in the UIA 1994, care has been taken to protect the confidentiality of company-specific information while still conveying accurate and complete statistical data. A feature article, ``Comparison of Uranium Mill Tailings Reclamation in the United States and Canada,`` is included in the UIA 1994. Data on uranium raw materials activities including exploration activities and expenditures, EIA-estimated 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 purchases of uranium and enrichment services, and uranium inventories, enrichment feed deliveries (actual and projected), and unfilled market requirements are shown in Chapter 2.

  18. Uranium industry annual 1998

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-04-22

    The Uranium Industry Annual 1998 (UIA 1998) provides current statistical data on the US uranium industry`s activities relating to uranium raw materials and uranium marketing. It contains data for the period 1989 through 2008 as collected on the Form EIA-858, ``Uranium Industry Annual Survey.`` Data provides a comprehensive statistical characterization of the industry`s activities for the survey year and also include some information about industry`s plans and commitments for the near-term future. Data on uranium raw materials activities for 1989 through 1998, 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 2008, including purchases of uranium and enrichment services, enrichment feed deliveries, uranium fuel assemblies, filled and unfilled market requirements, and uranium inventories, are shown in Chapter 2. The methodology used in the 1998 survey, including data edit and analysis, is described in Appendix A. The methodologies for estimation of resources and reserves are described in Appendix B. A list of respondents to the ``Uranium Industry Annual Survey`` is provided in Appendix C. The Form EIA-858 ``Uranium Industry Annual Survey`` is shown in Appendix D. For the readers convenience, metric versions of selected tables from Chapters 1 and 2 are presented in Appendix E along with the standard conversion factors used. A glossary of technical terms is at the end of the report. 24 figs., 56 tabs.

  19. URANIUM RECOVERY PROCESS

    Science.gov (United States)

    Bailes, R.H.; Long, R.S.; Olson, R.S.; Kerlinger, H.O.

    1959-02-10

    A method is described for recovering uranium values from uranium bearing phosphate solutions such as are encountered in the manufacture of phosphate fertilizers. The solution is first treated with a reducing agent to obtain all the uranium in the tetravalent state. Following this reduction, the solution is treated to co-precipitate the rcduced uranium as a fluoride, together with other insoluble fluorides, thereby accomplishing a substantially complete recovery of even trace amounts of uranium from the phosphate solution. This precipitate usually takes the form of a complex fluoride precipitate, and after appropriate pre-treatment, the uranium fluorides are leached from this precipitate and rccovered from the leach solution.

  20. Uranium comparison by means of AMS and ICP-MS and Pu and 137Cs results around an Italian Nuclear Power Plant

    Directory of Open Access Journals (Sweden)

    De Cesare M.

    2015-01-01

    Full Text Available Italy built and commissioned 4 nuclear power plants between 1958-1978, which delivered a total of 1500 MW. All four were closed down after the Chernobyl accident following a referendum in 1987. One of the plants was Garigliano, commissioned in 1959. This plant used a 160 MW BWR1 (SEU of 2.3 % and was operational from 1964 to 1979, when it was switched off for maintenance. It was definitively stopped in 1982, and is presently being decommissioned. We report here details on the chemistry procedure and on the measurements for soil samples, collected up to 4.5 km from the Nuclear Plant. A comparison between uranium (238U concentration as determined by means of AMS (Accelerator Mass Spectrometry and by ICP-MS (Inductively Coupled Plasma-Mass Spectrometry techniques respectively at the ANU (Australian National University and at the Ecowise company in Canberra, Australia, is reported, as well as 236U and 239;240Pu concentration results detected by AMS. 236U/238U and 240Pu/239Pu isotopic ratios by means of AMS are also provided. A contamination from Chernobyl is visible in the 137Cs/239+240Pu activity ratio measurements.

  1. Uranium comparison by means of AMS and ICP-MS and Pu and 137Cs results around an Italian Nuclear Power Plant

    Science.gov (United States)

    De Cesare, M.; Tims, S. G.; Fifield, L. K.

    2015-04-01

    Italy built and commissioned 4 nuclear power plants between 1958-1978, which delivered a total of 1500 MW. All four were closed down after the Chernobyl accident following a referendum in 1987. One of the plants was Garigliano, commissioned in 1959. This plant used a 160 MW BWR1 (SEU of 2.3 %) and was operational from 1964 to 1979, when it was switched off for maintenance. It was definitively stopped in 1982, and is presently being decommissioned. We report here details on the chemistry procedure and on the measurements for soil samples, collected up to 4.5 km from the Nuclear Plant. A comparison between uranium (238U) concentration as determined by means of AMS (Accelerator Mass Spectrometry) and by ICP-MS (Inductively Coupled Plasma-Mass Spectrometry) techniques respectively at the ANU (Australian National University) and at the Ecowise company in Canberra, Australia, is reported, as well as 236U and 239;240Pu concentration results detected by AMS. 236U/238U and 240Pu/239Pu isotopic ratios by means of AMS are also provided. A contamination from Chernobyl is visible in the 137Cs/239+240Pu activity ratio measurements.

  2. Geology, Bedrock - BEDROCK_TOPOGRAPHY_MM36_IN: Bedrock Topography Contours, Indiana (Indiana Geological Survey, 1:500,000, Line Shapefile)

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — Bedrock topography was converted from the original published map, Indiana Geological Survey Miscellaneous Map 36. The contours define the elevation/topography of the...

  3. Uranium Processing Facility

    Data.gov (United States)

    Federal Laboratory Consortium — An integral part of Y‑12's transformation efforts and a key component of the National Nuclear Security Administration's Uranium Center of Excellence, the Uranium...

  4. Cathodoluminescence of uranium oxides

    Energy Technology Data Exchange (ETDEWEB)

    Winer, K.; Colmenares, C.; Wooten, F.

    1984-08-09

    The cathodoluminescence of uranium oxide surfaces prepared in-situ from clean uranium exposed to dry oxygen was studied. The broad asymmetric peak observed at 470 nm is attributed to F-center excitation.

  5. Uranium industry annual 1995

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-05-01

    The Uranium Industry Annual 1995 (UIA 1995) provides current statistical data on the U.S. uranium industry`s activities relating to uranium raw materials and uranium marketing. The UIA 1995 is prepared for use by the Congress, Federal and State agencies, the uranium and nuclear electric utility industries, and the public. It contains data for the period 1986 through 2005 as collected on the Form EIA-858, ``Uranium Industry Annual Survey``. Data collected on the ``Uranium Industry Annual Survey`` provide a comprehensive statistical characterization of the industry`s plans and commitments for the near-term future. Where aggregate data are presented in the UIA 1995, care has been taken to protect the confidentiality of company-specific information while still conveying accurate and complete statistical data. Data on uranium raw materials activities for 1986 through 1995 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 2005, 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. The methodology used in the 1995 survey, including data edit and analysis, is described in Appendix A. The methodologies for estimation of resources and reserves are described in Appendix B. A list of respondents to the ``Uranium Industry Annual Survey`` is provided in Appendix C. For the reader`s convenience, metric versions of selected tables from Chapters 1 and 2 are presented in Appendix D along with the standard conversion factors used. A glossary of technical terms is at the end of the report. 14 figs., 56 tabs.

  6. Separation Of Uranium And Plutonium Isotopes For Measurement By Multi Collector Inductively Coupled Plasma Mass Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Martinelli, R E; Hamilton, T F; Williams, R W; Kehl, S R

    2009-03-29

    Uranium (U) and plutonium (Pu) isotopes in coral soils, contaminated by nuclear weapons testing in the northern Marshall Islands, were isolated by ion-exchange chromatography and analyzed by mass spectrometry. The soil samples were spiked with {sup 233}U and {sup 242}Pu tracers, dissolved in minerals acids, and U and Pu isotopes isolated and purified on commercially available ion-exchange columns. The ion-exchange technique employed a TEVA{reg_sign} column coupled to a UTEVA{reg_sign} column. U and Pu isotope fractions were then further isolated using separate elution schemes, and the purified fractions containing U and Pu isotopes analyzed sequentially using multi-collector inductively coupled plasma mass spectrometer (MCICP-MS). High precision measurements of {sup 234}U/{sup 235}U, {sup 238}U/{sup 235}U, {sup 236}U/{sup 235}U, and {sup 240}Pu/{sup 239}Pu in soil samples were attained using the described methodology and instrumentation, and provide a basis for conducting more detailed assessments of the behavior and transfer of uranium and plutonium in the environment.

  7. Investigating Uranium Isotopic Distributions in Environmental Samples Using AMS and MC-ICPMS

    Energy Technology Data Exchange (ETDEWEB)

    Buchholz, B A; Brown, T A; Hamilton, T F; Hutcheon, I D; Marchetti, A A; Martinelli, R E; Ramon, E C; Tumey, S J; Williams, R W

    2005-12-09

    Major, minor, and trace uranium isotopes were measured at Lawrence Livermore National Laboratory in environmentally acquired samples using different instruments to span large variations in concentrations. Multi-collector inductively-coupled plasma mass spectrometry (MC-ICPMS) can be used to measure major and minor isotopes: {sup 238}U, {sup 235}U, {sup 234}U and {sup 236}U. Accelerator mass spectrometry (AMS) can be used to measure minor and trace isotopes: {sup 234}U, {sup 236}U, and {sup 233}U. The main limit of quantification for minor or trace uranium isotopes is the abundance sensitivity of the measurement technique; i.e., the ability to measure a minor or trace isotope of mass M in the presence of a major isotope at M{+-}1 mass units. The abundance sensitivity for {sup 236}U/{sup 235}U isotope ratio measurements using MC-ICPMS is around {approx}2x10{sup -6}. This compares with a {sup 236}U/{sup 235}U abundance sensitivity of {approx}1x10{sup -7} for the current AMS system, with the expectation of 2-3 orders of magnitude improvement in sensitivity with the addition of another high energy filter. Comparing {sup 236}U/{sup 234}U from MC-ICPMS and AMS produced agreement within {approx}10% for samples at {sup 236}U levels high enough to be measurable by both techniques.

  8. Assessing potential risks from exposure to natural uranium in well water

    Energy Technology Data Exchange (ETDEWEB)

    Hakonson-Hayes, A.C.; Fresquez, P.R. E-mail: fresquezp@lanl.gov; Whicker, F.W

    2002-07-01

    Over 50% of the wells in the Nambe region of northern New Mexico exceed the US Environmental Protection Agency's recommended drinking water standard of 20 {mu}g l{sup -1} for {sup 238}U; the highest in the area was measured at 1200 {mu}g U l{sup -1}. Uranium uptake was estimated in tomato (Lycopersicon esculentum), squash (Cucurbita pepo), lettuce (Lactuca scarriola), and radish (Raphanus sativus) irrigated with Nambe well water containing <1, 150, 500, and 1200 {mu}g U l{sup -1}. Plant uptake and human dose and toxicity associated with ingestion of water and produce and inhalation of irrigated soil related to gardening activities were evaluated. Uranium concentration in plants increased linearly with increasing U concentration in irrigation water, particularly in lettuce and radish. The estimated total committed effective dose for 70 years of maximum continuous exposure, via the three pathways to well water containing 1200 {mu}g U l{sup -1}, was 0.17 mSv with a corresponding kidney concentration of 0.8 {mu}g U g{sup -1} kidney.

  9. A procedural manual for measurement of uranium and thorium isotopes utilizing the USGS-Stanford Finnegan Mat 262

    Science.gov (United States)

    Shamp, Donald D.

    2001-01-01

    Over the past several decades investigators have extensively examined the 238U-234U- 230Th systematics of a variety of geologic materials using alpha spectroscopy. Analytical uncertainty for 230Th by alpha spectroscopy has been limited to about 2% (2σ). The advantage of thermal ionization mass spectroscopy (TIMS), introduced by Edwards and co-workers in the late 1980’s is the increased detectability of these isotopes by a factor of ~200, and decreases in the uncertainty for 230Th to about 5‰ (2σ) error. This report is a procedural manual for using the USGS-Stanford Finnegan-Mat 262 TIMS to collect and isolate Uranium and Thorium isotopic ratio data. Chemical separation of Uranium and Thorium from the sample media is accomplished using acid dissolution and then processed using anion exchange resins. The Finnegan-Mat262 Thermal Ionization Mass Spectrometer (TIMS) utilizes a surface ionization technique in which nitrates of Uranium and Thorium are placed on a source filament. Upon heating, positive ion emission occurs. The ions are then accelerated and focused into a beam which passes through a curved magnetic field dispersing the ions by mass. Faraday cups and/or an ion counter capture the ions and allow for quantitative analysis of the various isotopes.

  10. Study on Removing Micro-neptunium From Milligramme Uranium

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>In the production of radioisotopes and neutron activation analysis, it is very important to know the fast neutron densities, so that the yields of the radioistopes can be estimated. The 238U (n, 2n) 237U reactor

  11. 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....

  12. Forsmark site investigation. Bedrock geology - overview and excursion guide

    Energy Technology Data Exchange (ETDEWEB)

    Stephens, Michael B. (Geological Survey of Sweden, Uppsala (Sweden))

    2010-09-15

    Bearing in mind the significance of the bedrock data from the ground surface for the geological 3D modelling work, SKB decided to present excursion guides that serve in the demonstration of the bedrock geology at the ground surface in both the Forsmark (this guide) and Laxemar-Simpevarp areas. An excursion guide is also available for the Olkiluoto area in south-western Finland, which has been selected for the construction of a repository for the disposal of highly radioactive, spent nuclear fuel in Finland. The current excursion guide presents the bedrock geology and describes in detail the character of the bedrock at ten representative outcrops or outcrop areas at the ground surface in the site investigation area at Forsmark. All localities are located within or immediately adjacent to the proposed repository volume selected by SKB

  13. Oskarshamn site investigation. Bedrock geology - overview and excursion guide

    Energy Technology Data Exchange (ETDEWEB)

    Wahlgren, Carl-Henric (Geological Survey of Sweden, Uppsala (Sweden))

    2010-09-15

    Bearing in mind the significance of the bedrock data from the ground surface for the geological 3D modelling work, SKB decided to present excursion guides that serve in the demonstration of the bedrock geology at the ground surface in both the Forsmark and Laxemar-Simpevarp (this guide) areas. An excursion guide is also available for the Olkiluoto area in south-western Finland, which has been selected for the construction of a repository for the disposal of highly radioactive, spent nuclear fuel. The current excursion guide presents the bedrock geology and describes in detail the character of the bedrock at eight representative outcrops or outcrop areas at the ground surface in the site investigation area at Laxemar-Simpevarp and at one locality north of this area, i.e. at a total of nine localities

  14. Digital bedrock geologic map of the Andover quadrangle, Vermont

    Data.gov (United States)

    Vermont Center for Geographic Information — Digital Data from VG96-31A Ratcliffe, N.M., 1996, Digital bedrock geologic map of the Andover quadrangle, Vermont: USGS Open-File Report 96-31-A, 2 plates, scale...

  15. Digital compilation bedrock geologic map of the Milton quadrangle, Vermont

    Data.gov (United States)

    Vermont Center for Geographic Information — Digital Data from VG95-8A Dorsey, R, Doolan, B, Agnew, PC, Carter, CM, Rosencrantz, EJ, and Stanley, RS, 1995, Digital compilation bedrock geologic map of the Milton...

  16. Bedrock Geologic Map of Charlotte, Vermont

    Data.gov (United States)

    Vermont Center for Geographic Information — Digital Data from VG09-5 Gale, M., Kim, J., Earle, H., Clark, A., Smith, T., and Petersen, K., 2009, Bedrock Geologic Map of Charlotte, Vermont: VGS Open-File Report...

  17. Bedrock Geologic Map of the Bristol, VT Quadrangle

    Data.gov (United States)

    Vermont Center for Geographic Information — Digital data from VG13-1 Kim, J, Weber, E, and Klepeis, K, 2013, Bedrock Geologic Map of the Bristol, VT Quadrangle: Vermont Geological Survey Open File Report...

  18. Digital bedrock geologic map of the Johnson quadrangle, Vermont

    Data.gov (United States)

    Vermont Center for Geographic Information — Digital Data from VG98-2 Thompson, PJ and Thompson, TB, 1998, Digital bedrock geologic map of the Johnson quadrangle, Vermont: VGS Open-File Report VG98-2, 2 plates,...

  19. Bedrock Geologic Map of the Underhill quadrangle, Vermont

    Data.gov (United States)

    Vermont Center for Geographic Information — Digital Data from VG03-4B Doolan, B., Cherchetti, L., Holt, J., Ryan, J., Hengstenburg, C., and Rosencrantz, E., 2003, Bedrock Geologic Map of the Underhill...

  20. Digital bedrock geologic map of the Eden quadrangle, Vermont

    Data.gov (United States)

    Vermont Center for Geographic Information — Digital Data from VG98-3 Kim, J, Springston, G, and Gale, M, 1998, Digital bedrock geologic map of the Eden quadrangle, Vermont: VGS Open-File Report VG98-3, 2...

  1. Digital bedrock geologic map of the Cavendish quadrangle, Vermont

    Data.gov (United States)

    Vermont Center for Geographic Information — Digital Data from VG95-203A Ratcliffe, NM, 1995, Digital bedrock geologic map of the Cavendish quadrangle, Vermont: USGS Open-File Report 95-203, 2 plates, scale...

  2. Digital compilation bedrock geologic map of the Warren quadrangle, Vermont

    Data.gov (United States)

    Vermont Center for Geographic Information — Digital Data from VG95-4A Walsh, GJ, Haydock, S, Prewitt, J, Kraus, J, Lapp, E, O'Loughlin, S, and Stanley, RS, 1995, Digital compilation bedrock geologic map of the...

  3. Digital bedrock geologic map of the Saxtons River quadrangle, Vermont

    Data.gov (United States)

    Vermont Center for Geographic Information — Digital Data from VG96-52A Ratcliffe, NM and Armstrong, TR, 1996, Digital bedrock geologic map of the Saxtons River quadrangle, Vermont, USGS Open-File Report...

  4. Bedrock geologic map of the town of Williston, Vermont

    Data.gov (United States)

    Vermont Center for Geographic Information — Digital Data from VG07-4, Kim, J., Gale, M., Thompson, P.J. and Derman, K., 2007, Bedrock geologic map of the town of Williston, Vermont: Vermont Geological Survey...

  5. Bedrock Geologic Map of the Essex Junction Quadrangle, Vermont

    Data.gov (United States)

    Vermont Center for Geographic Information — Digital data from VG12-3, Gale, M., Kim. J., and Ruksznis, A., 2012, Bedrock Geologic Map of the essex Junction Quadrangle: Vermont Geological Survey Open File...

  6. Digital bedrock geologic map of the Rochester quadrangle, Vermont

    Data.gov (United States)

    Vermont Center for Geographic Information — Digital Data from VG96-33A Walsh, GJ and Falta, CK, 1996, Digital bedrock geologic map of the Rochester quadrangle, Vermont: USGS Open-File Report 96-33-A, 2 plates,...

  7. Digital bedrock geologic map of the Weston quadrangle, Vermont

    Data.gov (United States)

    Vermont Center for Geographic Information — Digital Data from VG96-526A Ratcliffe, NM and Burton, WC, 1996, Digital bedrock geologic map of the Weston quadrangle, Vermont: USGS Open-File Report 96-526, 2...

  8. Digital compilation bedrock geologic map of the Lincoln quadrangle, Vermont

    Data.gov (United States)

    Vermont Center for Geographic Information — Digital Data from VG95-5A Stanley, R, DelloRusso, V, Haydock, S, Lapp, E, O'Loughlin, S, Prewitt, J,and Tauvers, PR, 1995, Digital compilation bedrock geologic map...

  9. Digital bedrock geologic map of the Chester quadrangle, Vermont

    Data.gov (United States)

    Vermont Center for Geographic Information — Digital Data from VG95-576A Ratcliffe, N.M., 1995, Digital bedrock geologic map of the Chester quadrangle, Vermont: USGS Open-File Report 95-576, 2 plates, scale...

  10. Standard test method for isotopic abundance analysis of uranium hexafluoride and uranyl nitrate solutions by multi-collector, inductively coupled plasma-mass spectrometry

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2014-01-01

    1.1 This test method covers the isotopic abundance analysis of 234U, 235U, 236U and 238U in samples of hydrolysed uranium hexafluoride (UF6) by inductively coupled plasma source, multicollector, mass spectrometry (ICP-MC-MS). The method applies to material with 235U abundance in the range of 0.2 to 6 % mass. This test method is also described in ASTM STP 1344. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  11. Uranium in well drinking water of Kabul, Afghanistan and its effective, low-cost depuration using Mg-Fe based hydrotalcite-like compounds.

    Science.gov (United States)

    Kato, Masashi; Azimi, Mohammad Daud; Fayaz, Said Hafizullah; Shah, Muhammad Dawood; Hoque, Md Zahirul; Hamajima, Nobuyuki; Ohnuma, Shoko; Ohtsuka, Tomomi; Maeda, Masao; Yoshinaga, Masafumi

    2016-12-01

    Toxic elements in drinking water have great effects on human health. However, there is very limited information about toxic elements in drinking water in Afghanistan. In this study, levels of 10 elements (chromium, nickel, copper, arsenic, cadmium, antimony, barium, mercury, lead and uranium) in 227 well drinking water samples in Kabul, Afghanistan were examined for the first time. Chromium (in 0.9% of the 227 samples), arsenic (7.0%) and uranium (19.4%) exceeded the values in WHO health-based guidelines for drinking-water quality. Maximum chromium, arsenic and uranium levels in the water samples were 1.3-, 10.4- and 17.2-fold higher than the values in the guidelines, respectively. We next focused on uranium, which is the most seriously polluted element among the 10 elements. Mean ± SD (138.0 ± 1.4) of the (238)U/(235)U isotopic ratio in the water samples was in the range of previously reported ratios for natural source uranium. We then examined the effect of our originally developed magnesium (Mg)-iron (Fe)-based hydrotalcite-like compounds (MF-HT) on adsorption for uranium. All of the uranium-polluted well water samples from Kabul (mean ± SD = 190.4 ± 113.9 μg/L; n = 11) could be remediated up to 1.2 ± 1.7 μg/L by 1% weight of our MF-HT within 60 s at very low cost (water from Kabul. Since our depurative is effective for remediation of arsenic as shown in our previous studies, its practical use in Kabul may be encouraged.

  12. Uranium hexafluoride public risk

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, D.R.; Hui, T.E.; Yurconic, M.; Johnson, J.R.

    1994-08-01

    The limiting value for uranium toxicity in a human being should be based on the concentration of uranium (U) in the kidneys. The threshold for nephrotoxicity appears to lie very near 3 {mu}g U per gram kidney tissue. There does not appear to be strong scientific support for any other improved estimate, either higher or lower than this, of the threshold for uranium nephrotoxicity in a human being. The value 3 {mu}g U per gram kidney is the concentration that results from a single intake of about 30 mg soluble uranium by inhalation (assuming the metabolism of a standard person). The concentration of uranium continues to increase in the kidneys after long-term, continuous (or chronic) exposure. After chronic intakes of soluble uranium by workers at the rate of 10 mg U per week, the concentration of uranium in the kidneys approaches and may even exceed the nephrotoxic limit of 3 {mu}g U per gram kidney tissue. Precise values of the kidney concentration depend on the biokinetic model and model parameters assumed for such a calculation. Since it is possible for the concentration of uranium in the kidneys to exceed 3 {mu}g per gram tissue at an intake rate of 10 mg U per week over long periods of time, we believe that the kidneys are protected from injury when intakes of soluble uranium at the rate of 10 mg U per week do not continue for more than two consecutive weeks. For long-term, continuous occupational exposure to low-level, soluble uranium, we recommend a reduced weekly intake limit of 5 mg uranium to prevent nephrotoxicity in workers. Our analysis shows that the nephrotoxic limit of 3 {mu}g U per gram kidney tissues is not exceeded after long-term, continuous uranium intake at the intake rate of 5 mg soluble uranium per week.

  13. Geology, Bedrock - BEDROCK_GEOLOGY_RGM_250K_IN: Bedrock geology of Indiana, from the Regional Geologic Map Series of the Indiana Geological Survey (Indiana Geological Survey, 1:250,000, Polygon Shapefile)

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — BEDROCK_GEOL_RGM_IN is a polygon shapefile that shows the bedrock geology of the state of Indiana, produced from the Indiana Geological Survey Regional Geologic Map...

  14. Bioremediation of uranium contamination with enzymatic uranium reduction

    Science.gov (United States)

    Lovley, D.R.; Phillips, E.J.P.

    1992-01-01

    Enzymatic uranium reduction by Desulfovibrio desulfuricans readily removed uranium from solution in a batch system or when D. desulfuricans was separated from the bulk of the uranium-containing water by a semipermeable membrane. Uranium reduction continued at concentrations as high as 24 mM. Of a variety of potentially inhibiting anions and metals evaluated, only high concentrations of copper inhibited uranium reduction. Freeze-dried cells, stored aerobically, reduced uranium as fast as fresh cells. D. desulfuricans reduced uranium in pH 4 and pH 7.4 mine drainage waters and in uraniumcontaining groundwaters from a contaminated Department of Energy site. Enzymatic uranium reduction has several potential advantages over other bioprocessing techniques for uranium removal, the most important of which are as follows: the ability to precipitate uranium that is in the form of a uranyl carbonate complex; high capacity for uranium removal per cell; the formation of a compact, relatively pure, uranium precipitate.

  15. Uranium isotopes (U-234/U-238) in rivers of the Yukon Basin (Alaska and Canada) as an aid in identifying water sources, with implications for monitoring hydrologic change in arctic regions

    Science.gov (United States)

    Kraemer, Thomas F.; Brabets, Timothy P.

    2012-01-01

    The ability to detect hydrologic variation in large arctic river systems is of major importance in understanding and predicting effects of climate change in high-latitude environments. Monitoring uranium isotopes (234U and 238U) in river water of the Yukon River Basin of Alaska and northwestern Canada (2001–2005) has enhanced the ability to identify water sources to rivers, as well as detect flow changes that have occurred over the 5-year study. Uranium isotopic data for the Yukon River and major tributaries (the Porcupine and Tanana rivers) identify several sources that contribute to river flow, including: deep groundwater, seasonally frozen river-valley alluvium groundwater, and high-elevation glacial melt water. The main-stem Yukon River exhibits patterns of uranium isotopic variation at several locations that reflect input from ice melt and shallow groundwater in the spring, as well as a multi-year pattern of increased variability in timing and relative amount of water supplied from higher elevations within the basin. Results of this study demonstrate both the utility of uranium isotopes in revealing sources of water in large river systems and of incorporating uranium isotope analysis in long-term monitoring of arctic river systems that attempt to assess the effects of climate change.

  16. Environmental behaviour and bioavailability of Depleted Uranium (DU) material

    Energy Technology Data Exchange (ETDEWEB)

    Oeh, U.; Gerstmann, U.; Schimmack, W.; Szymczak, W.; Li, W.B.; Hoellriegl, V.; Roth, P.; Paretzke, H.G. [GSF - National Research Center for Environment and Health, Inst. of Radiation Protection, Neuherberg (Germany)

    2005-07-01

    This work was performed to assess a possible health risk of depleted uranium (DU) for residents and KFOR personnel serving on the Balkans. Therefore, the environmental behaviour and bioavailability of DU material have been explored. In order to investigate the environmental impact of DU ammunition, leaching experiments were carried out. DU penetrators were buried in soil filled in columns. The soil was irrigated (16 mm/week) and the uranium isotopes {sup 238}U and {sup 235}U which were washed out and transported into the eluate were determined by inductively coupled plasma mass spectrometry (ICP-MS). After one year, an average of 1.7% of the original DU material corroded. About 40% of the corrosion products were located on the surface of the penetrator, 60% were recovered in the soil. On the other hand, only very small amounts of the DU material could be found in the eluate (about 1 ppm per year) suggesting a low solubility of DU and the corrosion products and/or a strong sorption to the soil. In another part of the study, the solubility of DU material in human body fluids was investigated to assess the bioavailability after oral intake and inhalation of DU particles. Therefore, DU corrosion products were powdered and incubated in artificial gastric juice and simulated lung fluid. About three-fourths of the DU material was dissolved in artificial gastric juice after 30 minutes. This fraction could not be increased, even when the incubation time was extended to 120 minutes. The dissolution of DU material in artificial lung fluid showed a distinct bi-phasic course with a readily soluble fraction and a fraction of very low solubility. These findings suggest that the DU corrosion products consist mainly of two types of uranium oxides, hexavalent and fast soluble compounds and tetravalent compounds with low solubility. Additional measurements with time-of-flight secondary ion mass spectrometry (TOF-SIMS) of DU corrosion material support this conclusion. The resulting

  17. CHEMICAL TOXICITY OF URANIUM

    Directory of Open Access Journals (Sweden)

    Sermin Cam

    2007-06-01

    Full Text Available Uranium, occurs naturally in the earth’s crust, is an alpha emitter radioactive element from the actinide group. For this reason, U-235 and U-238, are uranium isotopes with long half lives, have got radiological toxicity. But, for natural-isotopic-composition uranium (NatU, there is greater risk from chemical toxicity than radiological toxicity. When uranium is get into the body with anyway, also its chemical toxicity must be thought. [TAF Prev Med Bull 2007; 6(3.000: 215-220

  18. METHOD OF ROLLING URANIUM

    Science.gov (United States)

    Smith, C.S.

    1959-08-01

    A method is described for rolling uranium metal at relatively low temperatures and under non-oxidizing conditions. The method involves the steps of heating the uranium to 200 deg C in an oil bath, withdrawing the uranium and permitting the oil to drain so that only a thin protective coating remains and rolling the oil coated uranium at a temperature of 200 deg C to give about a 15% reduction in thickness at each pass. The operation may be repeated to accomplish about a 90% reduction without edge cracking, checking or any appreciable increase in brittleness.

  19. PRODUCTION OF URANIUM

    Science.gov (United States)

    Ruehle, A.E.; Stevenson, J.W.

    1957-11-12

    An improved process is described for the magnesium reduction of UF/sub 4/ to produce uranium metal. In the past, there have been undesirable premature reactions between the Mg and the bomb liner or the UF/sub 4/ before the actual ignition of the bomb reaction. Since these premature reactions impair the yield of uranium metal, they have been inhibited by forming a protective film upon the particles of Mg by reacting it with hydrated uranium tetrafluoride, sodium bifluoride, uranyl fluoride, or uranium trioxide. This may be accomplished by adding about 0.5 to 2% of the additive to the bomb charge.

  20. The use of the uranium isotopic model on the study of aquifers at Morro do Ferro, Pocos de Caldas, Minas Gerais State, Brazil; Utilizacao de modelo isotopico de uranio no estudo de aquiferos do Morro do Ferro, Pocos de Caldas (MG)

    Energy Technology Data Exchange (ETDEWEB)

    Bonotto, Daniel M. [UNESP, Rio Claro, SP (Brazil). Inst. de Geociencias e Ciencias Exatas

    1994-03-01

    Uranium isotopic analyses were performed in groundwaters from several boreholes drilled at the thorium and rare earth deposit located at Morro do Ferro, near the centre of the Pocos de Caldas Plateau, Minas Gerais State, Brazil. The samples were collected during dry and wet periods, proceeding from aquifers developed in the weathered mantle due to in situ intense alteration, with the weathered zone establishing an argillaceous laterite greater than 100 m thick. The {sup 234} U/{sup 238} U activity ratio and U content measured for each sample by alpha spectrometry were used to evaluate the applicability in the area of the model developed to deduce proportions of groundwaters in a mixture. The influence of the rainfall on the utilization of the uranium isotopic model was considered, and also it was possible to suggest which boreholes would be able to supply samples representing different systems of circulation of groundwaters. (author). 5 figs., 2 tabs.

  1. Hydrogeology - AQUIFER_SYSTEMS_BEDROCK_IDNR_IN: Bedrock Aquifer Systems of Indiana (Indiana Department of Natural Resources, 1:500,000, Polygon Shapefile)

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — AQUIFER_SYSTEMS_BEDROCK_IDNR_IN is a polygon shapefile that shows bedrock aquifer systems of the State of Indiana. The source scale of the map depicting the aquifers...

  2. Evaluation of (n,n') scatteriung cross sections from 0. 8 to 2. 5 MeV for higher collective bands of /sup 232/Th and /sup 238/U in ''standard'' (CN + DI) and ''unified'' (Weidenmerller s-matrix) formalisms

    Energy Technology Data Exchange (ETDEWEB)

    Sheldon, E.; Chan, D.W.S.

    1982-01-01

    Angle-integrated cross sections for inelastic scattering of fast neutrons from 0.8 to 2.5 MeV on /sup 232/Th and /sup 238/U, proceeding to higher collective (quadrupole and octupole vibrational) states in the residual nuclei, have been computed in a standard and a unified approach; the resulting excitation functions have been compared with the experimental data of the Lowell group. In all calculations, a consistent set of optical potential and deformation parameters, as derived by Haouat and Lagrange of the Bruyeres group, was used. The standard formalism employed an incoherent sum of compound-nucleus (CN) and coupled-channels direct-interaction (DI) cross section, evaluated with the programs CINDY and KARJUP (Karlsruhe version of JUPITOR) respectively. Provision was made for the effect of level-width fluctuations and for competing neutron exit channels. The results in general compared well with the measured values, but in several instances disagreed significantly with the ENDF/B-V evaluated data. Still better agreement ensued from the use of the unified formalism based upon energy-averaged second moments of transformed S-matrix elements in a statistical approach developed by Weidenmueller at al. and embodied within a new fluctuation program NANCY with coupled channels and competing channels to generate and manipulate the grand ensemble of S-matrix elements. With only the coupling strengths as adjustable parameters, this offers a promising, reliable means of analysis well suited to the interpretation of neutron scattering on deformed actinide nuclei.

  3. Bedrock Channels: Towards a Process-Based Understanding

    Science.gov (United States)

    Parsons, D. R.; Darby, S. E.; Hackney, C. R.; Leyland, J.; Best, J.; Nicholas, A. P.; Aalto, R. E.; Horn, C. A. P. T., III; Thy, M. R.

    2014-12-01

    Most previous studies on the genesis and evolution of bedforms in large rivers have focused on aggradational bedforms within alluvial sediments, with very few investigations that concern either erosive bedform evolution or bedrock channel abrasion processes. Detailed understanding of the processes within bedrock reaches of river channels is vital if an improved understanding of formation and evolution of bedrock scours and bedforms are to be elucidated. The paper presents high-resolution bathymetry and sidescan derived from multibeam sonar (MBES) and detailed flow mapping by acoustic Doppler current profiling (ADCP) to illustrate, in intricate detail, relations between morphology, flow and sediment transport processes through a bedrock reach of the Mekong River (Cambodia) during a large flood event. A 2 by 5 km reach of the Mekong river near Sambor was surveyed with a RESON 7125 MBES system revealing incredible >40 m scour features within the bedrock substrate, with sidescan imagery also revealing the routing of alluvial sediment through the scours. A series of ADCP transects were obtained, both transverse and perpendicular to the primary downstream flow, that map the flows into, around and within these scour features. The paper will conclude by looking at how advances in measurement capability have permitted the detailed processes in such channels to be investigated for the first time at this scale.

  4. Uranium industry annual 1993

    Energy Technology Data Exchange (ETDEWEB)

    1994-09-01

    Uranium production in the United States has declined dramatically from a peak of 43.7 million pounds U{sub 3}O{sub 8} (16.8 thousand metric tons uranium (U)) in 1980 to 3.1 million pounds U{sub 3}O{sub 8} (1.2 thousand metric tons U) in 1993. This decline is attributed to the world uranium market experiencing oversupply and intense competition. Large inventories of uranium accumulated when optimistic forecasts for growth in nuclear power generation were not realized. The other factor which is affecting U.S. uranium production is that some other countries, notably Australia and Canada, possess higher quality uranium reserves that can be mined at lower costs than those of the United States. Realizing its competitive advantage, Canada was the world`s largest producer in 1993 with an output of 23.9 million pounds U{sub 3}O{sub 8} (9.2 thousand metric tons U). The U.S. uranium industry, responding to over a decade of declining market prices, has downsized and adopted less costly and more efficient production methods. The main result has been a suspension of production from conventional mines and mills. Since mid-1992, only nonconventional production facilities, chiefly in situ leach (ISL) mining and byproduct recovery, have operated in the United States. In contrast, nonconventional sources provided only 13 percent of the uranium produced in 1980. ISL mining has developed into the most cost efficient and environmentally acceptable method for producing uranium in the United States. The process, also known as solution mining, differs from conventional mining in that solutions are used to recover uranium from the ground without excavating the ore and generating associated solid waste. This article describes the current ISL Yang technology and its regulatory approval process, and provides an analysis of the factors favoring ISL mining over conventional methods in a declining uranium market.

  5. Radioactive contamination of the environment as a result of uranium production: a case study at the abandoned Lincang uranium mine, Yunnan Province, China

    Institute of Scientific and Technical Information of China (English)

    徐乐昌; 王焰新; 吕俊文; 卢学实; 刘耀驰; 刘晓阳

    2002-01-01

    The distribution of radioactive pollutants, such as 222Rn, U, Th and 226Ra in the air, surface waters, soils and crops around the Lincang uranium mine, Yunnan Province, China, is studied. The mechanical, geochemical and biogeochemical processes responsible for the transport and fate of the radioactive elements are discussed based on the monitoring data. The pollutants concentrations of effluents from the mine tunnels were dependent on pH and which were controlled by biochemical oxidation of sulfide in the ore/host rocks. Radon anomalies in air reached 4 km from the tailings pile depending on radon release from the site, topography and climate. 238U and 226Ra abnormities in stream sediments and soil were 40-90 cm deep and 790-800 m away downstream. Anomalies of radioactive contaminants of surface watercourses extended 7.5-13 km from the discharge of effluents of the site mainly depending on mechanical and chemical processes. There were about 2.86 ha rice fields and 1.59 km stream sediments contaminated. Erosion of tailings and mining debris with little or no containment or control accelerated the contamination processes.

  6. Distribution of natural radionuclides and uranium activity ratio in Gulf of Thailand sediments as base line data

    Energy Technology Data Exchange (ETDEWEB)

    Sahoo, S.K.; Hideki, A. [National Institute of Radiological Sciences (Japan); Kritsananuwat, R.; Fukushi, M. [Tokyo Metropolitan University (Japan); Chanyotha, S.; Pangza, K. [Chulalongkorn University (Thailand)

    2014-07-01

    This paper reports distribution of naturally occurring radionuclides and uranium activity ratio in marine sediments from selected coast, along the Gulf of Thailand to establish baseline data. Thailand has a plan to construct nuclear power plants (NPPs) as well as coal-fired thermal power plants to generate adequate and reliable electricity supply for rapid growth of industrialization. Therefore, it is important to focus not only on security and adequacy of power system but also on environmental protection and monitoring and risk assessment. To carry out environmental monitoring, baseline data plays a significant role. These data should be established and available before set up of mega projects that could impact the environment and health. Therefore, we have collected samples from five areas in the Gulf of Thailand, which are proposed as potential sites, to set up power plants by Thailand government. A total number of fifty-four marine sediment samples were collected. Gamma spectroscopy was used to determine the concentration of natural radionuclides e.g. {sup 226}Ra, {sup 228}Ac and {sup 40}K. Activity concentrations of {sup 226}Ra, {sup 228}Ac and {sup 40}K vary from 2.91-67.17 Bq/kg with an average of 26.64±14.57 Bq/kg, 4.42-109.17 Bq/kg with an average of 43.79±23.92 Bq/kg and 3.36-1004.56 Bq/kg with an average of 393.56±208.04 Bq/kg, respectively. The radiation hazard parameters including absorbed dose rate (D), annual effective dose equivalent (AEDE), radium equivalent activity (AGDE) and external hazard index (Hex) were calculated and compared with the international recommended values. We have noticed that sediments from two sites characterized by similar geological nature of landforms with a rocky coast have higher concentration of natural radionuclides. Concentration of uranium was determined using the inductively coupled plasma mass spectrometry (ICP-MS) and isotopic composition of {sup 234}U/{sup 238}U and {sup 235}U/{sup 238}U were determined using

  7. Uranium: abundance or shortage?

    Energy Technology Data Exchange (ETDEWEB)

    Steyn, J. [Energy Resources International, Inc., Washington, DC (United States)

    1997-09-01

    With large uranium stockpiles, particularly in the form of HEU, continuing to be the dominant factor in the world uranium market, buyers should be able to enter into attractive long-term commitments for the future. Nevertheless, producers are now able to see forward with some degree of certainty and are expected to meet their planned levels of production and demand. (author).

  8. Uranium triamidoamine chemistry.

    Science.gov (United States)

    Gardner, Benedict M; Liddle, Stephen T

    2015-07-01

    Triamidoamine (Tren) complexes of the p- and d-block elements have been well-studied, and they display a diverse array of chemistry of academic, industrial and biological significance. Such in-depth investigations are not as widespread for Tren complexes of uranium, despite the general drive to better understand the chemical behaviour of uranium by virtue of its fundamental position within the nuclear sector. However, the chemistry of Tren-uranium complexes is characterised by the ability to stabilise otherwise reactive, multiply bonded main group donor atom ligands, construct uranium-metal bonds, promote small molecule activation, and support single molecule magnetism, all of which exploit the steric, electronic, thermodynamic and kinetic features of the Tren ligand system. This Feature Article presents a current account of the chemistry of Tren-uranium complexes.

  9. Uranium dioxide electrolysis

    Science.gov (United States)

    Willit, James L.; Ackerman, John P.; Williamson, Mark A.

    2009-12-29

    This is a single stage process for treating spent nuclear fuel from light water reactors. The spent nuclear fuel, uranium oxide, UO.sub.2, is added to a solution of UCl.sub.4 dissolved in molten LiCl. A carbon anode and a metallic cathode is positioned in the molten salt bath. A power source is connected to the electrodes and a voltage greater than or equal to 1.3 volts is applied to the bath. At the anode, the carbon is oxidized to form carbon dioxide and uranium chloride. At the cathode, uranium is electroplated. The uranium chloride at the cathode reacts with more uranium oxide to continue the reaction. The process may also be used with other transuranic oxides and rare earth metal oxides.

  10. Mechanisms and Rates of Plucking of Experimental Bedrock Blocks

    Science.gov (United States)

    Harbor, D. J.; Wilkinson, C.; Helgans, E.; Kuehner, J. P.

    2015-12-01

    Plucking in bedrock channels can be the dominant erosional mechanism but is difficult to predict numerically due to variation in block shape and orientation in the flow, and the general lack of experimental data compared to alluvial sediments. In a 250 cm-long, 14 cm-wide flume, we modeled bedrock channels using a bedrock test zone consisting of flow over an upstream step of 0 to 1.6 cm, a bed slope of 0.5 to1.24%, and a changing downstream backwater control on the location of a hydraulic jump. With flow velocity from 50 to 100 cm/s and depth from 3 to 10 cm, the low-density bedrock may well characterize natural bedrock plucking events in larger rivers in flood. Plucking initiated in critical to supercritical flow near hydraulic jumps. The first blocks to move lift from both the upstream and downstream sides and then other blocks slide both up- and downstream or laterally once neighbors are removed. Initiation of motion from each new bedrock slab began with different size and shape of blocks exhibiting no protrusion relative to the surrounding bed. Block erodibility increased with step height and channel slope and following the removal of the first block. A pressure gradient within the block mass near the jump and velocity differential within the channel margin set the stage for block uplift, but flow structures likely provide the variability that initiates lift. Preliminary flow visualization using Particle Image Velocimetry aids the understanding of flow structures contributing to blocks lift. Negative and positive feedback to further plucking was observed by erosion and deposition of plucked blocks. After their initial removal, blocks can accumulate downstream and slow the flow over the eroded reach or the position of jumps and jets shift with block removal to promote further plucking.

  11. The assessment of human exposure to radionuclides from a uranium mill tailings release and mine dewatering effluent.

    Science.gov (United States)

    Ruttenber, A J; Kreiss, K; Douglas, R L; Buhl, T E; Millard, J

    1984-07-01

    This study provides an assessment of human exposure to radiation from a river system contaminated by radionuclides of the 238U decay series released through a dam break at a uranium mill tailings pond and by the continuous discharge of dewatering effluent from 2 uranium mines. The in vivo analyses of radionuclides in 6 Navajo Indians who lived near the river indicate no detectable elevations above background concentrations. Dose estimates for inhalation of suspended river sediment indicate a maximum annual 50-yr dose commitment of 204 mrem to the endosteum. Estimates of doses (50-yr dose commitments) from the ingestion of livestock range between 1 mrem (to liver) and 79 mrem (to bone) suggest that the major contribution to human exposure is from mine dewatering effluent that has been continuously released into the river system for many years. Although the estimated exposures do not exceed existing state or federal regulations, their magnitude justifies further measurement of radionuclides in animals and in the natural environment and the consideration of strategies to reduce radiation exposure to humans and animals.

  12. Uranium and radium activities measurements and calculation of effective doses in some drinking water samples in Morocco

    Directory of Open Access Journals (Sweden)

    Oum Keltoum Hakam

    2015-09-01

    Full Text Available Purpose: As a way of prevention, we have measured the activities of uranium and radium isotopes (234U, 238U, 226Ra, 228Ra for 30 drinking water samples collected from 11 wells, 9 springs (6 hot and 3 cold, 3 commercialised mineral water, and 7 tap water samples. Methods: Activities of the Ra isotopes were measured by ultra-gamma spectrometry using a low background and high efficiency well type germanium detector. The U isotopes were counted in an alpha spectrometer.Results: The measured Uranium and radium activities are similar to those published for other non-polluting regions of the world. Except in one commercialised gaseous water sample, and in two hot spring water samples, the calculated effective doses during one year are inferior to the reference level of 0.1 mSv/year recommended by the International Commission on Radiological Protection. Conclusion: These activities don't present any risk for public health in Morocco. The sparkling water of Oulmes is occasionally consumed as table water and waters of warm springs are not used as main sources of drinking water.  

  13. Determination of trace element concentrations and stable lead, uranium and thorium isotope ratios by quadrupole-ICP-MS in NORM and NORM-polluted sample leachates.

    Science.gov (United States)

    Mas, J L; Villa, M; Hurtado, S; García-Tenorio, R

    2012-02-29

    This work focuses on the monitoring of the potential pollution in scenarios that involve NORM-related industrial activities (environmental or in-door scenarios). The objective was to develop a method to determine extent and origin of the contamination, suitable for monitoring (i.e. simple, fast and economical) and avoiding the use of too many different instruments. It is presented a radiochemical method that allows the determination of trace element concentrations and 206Pb/207Pb/208Pb, 238U/234U and 232Th/230Th isotope ratios using a single sample aliquot and a single instrument (ICP-QMS). Eichrom UTEVA® extraction chromatography minicolumns were used to separate uranium and thorium in sample leachates. Independent ICP-MS determinations of uranium and thorium isotope ratios were carried out afterwards. Previously a small aliquot of the leachate was used for the determination of trace element concentrations and lead isotope ratios. Several radiochemical arrangements were tested to get maximum performances and simplicity of the method. The performances of the method were studied in terms of chemical yields of uranium and thorium and removal of the potentially interfering elements. The established method was applied to samples from a chemical industry and sediments collected in a NORM-polluted scenario. The results obtained from our method allowed us to infer not only the extent, but also the sources of the contamination in the area.

  14. Uranium and thorium in soils, mineral sands, water and food samples in a tin mining area in Nigeria with elevated activity.

    Science.gov (United States)

    Arogunjo, A M; Höllriegl, V; Giussani, A; Leopold, K; Gerstmann, U; Veronese, I; Oeh, U

    2009-03-01

    The activity concentrations of uranium and thorium have been determined in soils and mineral sands from the Nigerian tin mining area of Bisichi, located in the Jos Plateau, and from two control areas in Nigeria (Jos City and Akure) using high-purity germanium detectors (HPGe). High resolution sector field inductively coupled plasma mass spectroscopy (HR-SF-ICP-MS) was used to determine uranium and thorium in liquids and foodstuffs consumed locally in the mining area. The activities of uranium and thorium measured in the soils and mineral sands from Bisichi ranged from 8.7 kBq kg(-1) to 51 kBq kg(-1) for (238)U and from 16.8 kBq kg(-1) to 98 kBq kg(-1) for (232)Th, respectively. These values were significantly higher than those in the control areas of Jos City and Akure and than the reference values reported in the literature. They even exceeded the concentrations reported for areas of high natural radioactive background. Radionuclide concentrations in samples of the local foodstuffs and in water samples collected in Bisichi were found to be higher than UNSCEAR reference values. The results reveal the pollution potential of the mining activities on the surrounding areas.

  15. The use of ICP-MS and LA-ICP-MS techniques for uranium analysis in real-life swipe samples for safeguards purposes

    Energy Technology Data Exchange (ETDEWEB)

    Pestana, Rafael C.B.; Sarkis, Jorge E.S.; Carvalho, Elita F.U., E-mail: rcbpestana@gmail.com, E-mail: jesarkis@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Abreu Junior, Cassio H. [Centro de Energia Nuclear na Agricultura (CENA/USP), Piracicaba, SP (Brazil)

    2013-07-01

    Environmental swipe sampling for safeguards purposes is a powerful tool to detect undeclared materials and activities, and has been used by the International Atomic Energy Agency since 1997. This work describes the utilization of the inductively coupled plasma mass spectrometry (ICP-MS) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for determining uranium isotopic ratios in a real-life swipe samples collected in a conversion plant at IPEN/CNEN, Brazil. Uncertainties were estimated by following the International Organization for Standardization - Guide to the Expression of Uncertainties in Measurement (ISO GUM), with a confidence level of 95%. The major uncertainties percentage for n({sup 235}U)/n({sup 238}U) ratio for ICP-MS was 3% and for LA-ICP-MS was 30% The values of uranium isotopic ratios obtained for each technique demonstrate the viability of these analytical techniques as an alternative tool for uranium analysis in swipe samples for safeguards purposes. (author)

  16. Direct determination of uranium in human urine by Icp-SFMS; Determinacion directa de uranio en orina humana por ICP-SFMS

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez M, H. [ININ, Departamento de Quimica, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Yllera de Ll, A., E-mail: hector.hernandez520@gmail.com [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas, Departamento de Medio Ambiente, Av. Complutense 22, 28040 Madrid (Spain)

    2013-10-15

    The success of the measurement and the evaluation of the internal exposure are highly dependent of the effective capacities for the radiation measurement in biological samples (mainly urine and the feces). Usually, during the samples bioassay of human urine, a pre-concentration and purification of the radionuclides is carried out previously to the quantitative analysis. These stages, as the analysis time are the main source of uncertainty in the measurement process. In the uranium case, this is not necessary when are used mass spectrometry techniques, in particular, Mass Spectrometry of Magnetic Sector with Inductively Coupled Plasma (Icp-SFMS). This work presents the results obtained for the uranium analysis in samples of human urine during the participation in the inter-comparison exercises of the Association pour la Promotion de Controle de Qualite des Analyses de Biologie Medicale en Radiotoxicologie (PROCORAD) in the period 2010 and 2011. The analyses were realized directly in the diluted urine samples (dilution factor 1:20) in 5% of HNO{sub 3}. The obtained results, were normalized to the total urine sample (V = 0.5 L), these values coincide with the waited reference values of uranium in the urine sample. Additionally, were calculated the detection limits of {sup 235}U= 0.049 x 10{sup -3} μg L{sup -1} and {sup 238}U= 7.37 x 10{sup -3} μg L{sup -1}. (author)

  17. Modern Measurements of Uranium Decay Rates

    Science.gov (United States)

    Parsons-Moss, T.; Faye, S. A.; Williams, R. W.; Wang, T. F.; Renne, P. R.; Mundil, R.; Harrison, M.; Bandong, B. B.; Moody, K.; Knight, K. B.

    2015-12-01

    It has been widely recognized that accurate and precise decay constants (λ) are critical to geochronology as highlighted by the EARTHTIME initiative, particularly the calibration benchmarks λ235U and λ238U. [1] Alpha counting experiments in 1971[2] measured λ235U and λ238U with ~0.1% precision, but have never been independently validated. We are embarking on new direct measurements of λ235U, λ238U, λ234Th, and λ234U using independent approaches for each nuclide. For the measurement of λ235U, highly enriched 235U samples will be chemically purified and analyzed for U concentration and isotopic composition by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). Thin films will be electrodeposited from these solutions and the α activity will be measured in an α-γ coincidence counting apparatus, which allows reduced uncertainty in counting efficiency while achieving adequate counting statistics. For λ238U measurement we will measure ingrowth of 234Th in chemically purified, isotopically enriched 238U solutions, by quantitatively separating the Th and allowing complete decay to 234U. All of the measurements will be done using MC-ICP-MS aiming at 0.05% precision. This approach is expected to result in values of λ238U with less than 0.1% uncertainty, if combined with improved λ234Th measements. These will be achieved using direct decay measurements with an E-∆E charged particle telescope in coincidence with a gamma detector. This system allows measurement of 234Th β-decay and simultaneous detection and identification of α particles emitted by the 234U daughter, thus observing λ234U at the same time. The high-precision λ234U obtained by the direct activity measurements can independently verify the commonly used values obtained by indirect methods.[3] An overarching goal of the project is to ensure the quality of results including metrological traceability in order to facilitate implementation across diverse disciplines. [1] T

  18. Application of the grey system theory for forecasting the content of238U in soil near a uranium mine exhaust outlet%用灰色系统理论预测某铀矿排风井周边土壤中铀的质量分数

    Institute of Scientific and Technical Information of China (English)

    叶勇军; 丁德馨; 李向阳; 周星火; 刘栋

    2008-01-01

    为预测铀矿排风井周边土壤中铀的质量分数,基于灰色系统的建模、关联度分析和残差辨识理论,建立了常规GM(1,1)预测模型.根据2001-2006年某铀矿排风井周边土壤中铀质量分数的监测数据,证实该模型预测结果与实际监测结果吻合较好,并且预测精度等级较高;同时外推预测了2007年该铀矿排风井周边土壤中铀质量分数,预测结果与实际监测结果的相对误差为4.54%,表明GM(1,1)预测模型具有较高的实用价值,为铀矿排风井周边土壤中铀质量分数的预测提供了一种方便有效的方法.

  19. GeologicBedrock100K Units - color definitions

    Data.gov (United States)

    Vermont Center for Geographic Information — The bedrock geology was last mapped at a statewide scale 50 years ago at a scale of 1:250,000 (Doll and others, 1961). The 1961 map was compiled from 1:62,500-scale...

  20. GeologicBedrock100K Geochronology Sample Locations

    Data.gov (United States)

    Vermont Center for Geographic Information — The bedrock geology was last mapped at a statewide scale 50 years ago at a scale of 1:250,000 (Doll and others, 1961). The 1961 map was compiled from 1:62,500-scale...

  1. GeologicBedrock100K-Faults and Contacts

    Data.gov (United States)

    Vermont Center for Geographic Information — The bedrock geology was last mapped at a statewide scale 50 years ago at a scale of 1:250,000 (Doll and others, 1961). The 1961 map was compiled from 1:62,500-scale...

  2. Digital bedrock geologic map of the Plymouth quadrangle, Vermont

    Data.gov (United States)

    Vermont Center for Geographic Information — Digital Data from VG94-654A Walsh, G.J., and Ratcliffe, N.M., 1994, Digital bedrock geologic map of the Plymouth quadrangle, Vermont: USGS Open-File Report 94-654, 2...

  3. Bedrock hydrogeology Forsmark. Site descriptive modelling, SDM-Site Forsmark

    Energy Technology Data Exchange (ETDEWEB)

    Follin, Sven (SF GeoLogic AB, Taeby (Sweden))

    2008-12-15

    The Swedish Nuclear Fuel and Waste Management Company (SKB) has conducted site investigations at two different locations, the Forsmark and Laxemar-Simpevarp areas, with the objective of siting a final repository for spent nuclear fuel according to the KBS-3 concept. Site characterisation should provide all data required for an integrated evaluation of the suitability of the investigated site and an important component in the characterisation work is the development of a hydrogeological model. The hydrogeological model is used by repository engineering to design the underground facility and to develop a repository layout adapted to the site. It also provides input to the safety assessment. Another important use of the hydrogeological model is in the environmental impact assessment. This report presents the understanding of the hydrogeological conditions of the bedrock at Forsmark reached following the completion of the surface-based investigations and provides a summary of the bedrock hydrogeological model and the underlying data supporting its development. It constitutes the main reference on bedrock hydrogeology for the site descriptive model concluding the surface-based investigations at Forsmark, SDM-site, and is intended to describe the hydraulic properties and hydrogeological conditions of the bedrock at the site and to give the information essential for demonstrating understanding

  4. Bedload transport controls bedrock erosion under sediment-starved conditions

    Science.gov (United States)

    Beer, A. R.; Turowski, J. M.

    2015-07-01

    Fluvial bedrock incision constrains the pace of mountainous landscape evolution. Bedrock erosion processes have been described with incision models that are widely applied in river-reach and catchment-scale studies. However, so far no linked field data set at the process scale had been published that permits the assessment of model plausibility and accuracy. Here, we evaluate the predictive power of various incision models using independent data on hydraulics, bedload transport and erosion recorded on an artificial bedrock slab installed in a steep bedrock stream section for a single bedload transport event. The influence of transported bedload on the erosion rate (the "tools effect") is shown to be dominant, while other sediment effects are of minor importance. Hence, a simple temporally distributed incision model, in which erosion rate is proportional to bedload transport rate, is proposed for transient local studies under detachment-limited conditions. This model can be site-calibrated with temporally lumped bedload and erosion data and its applicability can be assessed by visual inspection of the study site. For the event at hand, basic discharge-based models, such as derivatives of the stream power model family, are adequate to reproduce the overall trend of the observed erosion rate. This may be relevant for long-term studies of landscape evolution without specific interest in transient local behavior. However, it remains to be seen whether the same model calibration can reliably predict erosion in future events.

  5. Comparison of femtosecond and nanosecond laser ablation inductively coupled plasma mass spectrometry for uranium isotopic measurements

    Energy Technology Data Exchange (ETDEWEB)

    Havrilla, George Joseph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); McIntosh, Kathryn Gallagher [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Judge, Elizabeth [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dirmyer, Matthew R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Campbell, Keri [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Gonzalez, Jhanis J. [Applied Spectra Inc., Fremont, CA (United States)

    2016-10-20

    Feasibility tests were conducted using femtosecond and nanosecond laser ablation inductively coupled plasma mass spectrometry for rapid uranium isotopic measurements. The samples used in this study consisted of a range of pg quantities of known 235/238 U solutions as dried spot residues of 300 pL drops on silicon substrates. The samples spanned the following enrichments of 235U: 0.5, 1.5, 2, 3, and 15.1%. In this direct comparison using these particular samples both pulse durations demonstrated near equivalent data can be produced on either system with respect to accuracy and precision. There is no question that either LA-ICP-MS method offers the potential for rapid, accurate and precise isotopic measurements of U10Mo materials whether DU, LEU or HEU. The LA-ICP-MS equipment used for this work is commercially available. The program is in the process of validating this work for large samples using center samples strips from Y-12 MP-1 LEU-Mo Casting #1.

  6. Dynamic response of Antarctic ice shelves to bedrock uncertainty

    Directory of Open Access Journals (Sweden)

    S. Sun

    2014-01-01

    Full Text Available Bedrock geometry is an essential boundary condition in ice sheet modelling. The shape of the bedrock on fine scales can influences ice sheet evolution, for example through the formation of pinning points that alter grounding line dynamics. Here we test the sensitivity of the BISICLES adaptive mesh ice sheet model to small amplitude height fluctuations on different spatial scales in the bed rock topography provided by bedmap2 in the catchments of Pine Island Glacier, the Amery Ice Shelf, and a region of East Antarctica including the Denman and Totten Glaciers. We generate an ensemble of bedrock topographies by adding random noise to the bedmap2 data with amplitude determined by the accompanying estimates of bedrock uncertainty. Lower frequency coherent noise, which generates broad spatial scale (over 10s of km errors in topography with relatively gently slopes, while higher frequency noise has steeper slopes over smaller spatial scales. We find that the small amplitude fluctuations result in only minor changes in the way these glaciers evolve. However, lower frequency noise is more important than higher frequency noise even when the features have the same height amplitudes and the total noise power is maintained. This provides optimism for credible sea level rise estimates with presently achievable densities of thickness measurements. Pine Island Glacier appears to be the most sensitive to errors in bed topography, while Lambert–Amery is stable under the present day observational data uncertainty. Totten–Denman region may undergo a retreat around Totten ice shelf, where the bedrock is lower than the sea level, especially if basal melt rates increase.

  7. Quaternary deposits and weathered bedrock material as a source of dangerous radon emissions in Estonia

    Directory of Open Access Journals (Sweden)

    Petersell Valter

    2015-06-01

    Full Text Available The risk of dangerous radon emissions in Estonia is high, being among the highest in Europe. In almost 33 per cent of Estonian land area, the content of radon in soil-contained air exceeds the safe limit for unrestricted construction (50 kBq/m3. In such high radon-risk areas the concentration of radon in soil-contained air ranges from 50 to 400 kBq/m3, in a few cases reaching up to 2,100 kBq/m3 exceeding the permitted level for residential areas. The situation is particularly serious in the northernmost part of the country, where uranium-rich graptolite argillite (Dictyonema shale and the Obolus phosphorite are close to ground surface and their particles are constituent pa