International Nuclear Information System (INIS)

The reactor fuel cycle based on uranium is described. The various stages in the cycle include mining of uranium ores followed by crushing and grinding, leaching and purification of leach liquor by ion exchange resin process or solvent extraction process, refining of uranium concentrate (yellow cake) by digesting with HNO_3 and then solvent extracting uranyl nitrate with TBP, conversion of uranyl nitrate to uranium hexafluoride, production of uranium metal, uranium enrichment, fabrication of reactor fuel elements and reprocessing of the spent fuel. Chemical reactions wherever they are involved are explained. (M.G.B.).

International Nuclear Information System (INIS)

Processes of production and purification (necessary for fabricating fuel elements) of powdery uranium dioxide with particle size up to 1000 #mu#m and more have been studied. Developed is continuous process of UO_2 production with above particle size by converting uranium hexafloride into UO_2 solid particles in fluidized bed while their interaction with water vapor and hydrogen on the uranium dioxide nucleus material. The method allows to conduct continuous selection from the apparatus of UO_2 powder fraction with particle size near 1000 #mu#m without nucleus material additional feed.

Energy Technology Data Exchange (ETDEWEB)

The US DOE manages the safe storage of approximately 650,000 tons of depleted uranium hexafluoride remaining from the Cold War. This slightly radioactive, but chemically active, material is contained in more than 46,000 steel storage cylinders that are located at Oak Ridge, Tennessee; Paducah, Kentucky; and Portsmouth, Ohio. Some of the cylinders are more than 40 years old, and approximately 17,500 are considered problem cylinders because their physical integrity is questionable. These cylinders require an annual visual inspection. The remainder of the 46,000-plus cylinders must be visually inspected every four years. Currently, the cylinder inspection program is extremely labor intensive. Because these inspections are accomplished visually, they may not be effective in the early detection of leaking cylinders. The inspection program requires approximately 12--14 full-time-equivalent (FTE) employees. At the cost of approximately $125K per FTE, ...

UK PubMed Central (United Kingdom)

ObjectivesWe undertook a meta-analysis to assess outcomes for drug-eluting (DES) and bare metal stents (BMS) in percutaneous coronary intervention (PCI) for unprotected...Full Text Available

International Nuclear Information System (INIS)

Repassivation resulting from the bared metal surface is a critical process for judging whether or not material suffers from corroding or immunizing. Nickel based alloys with high chromium content were developed to increase the corrosion resistant to sulphur compounds. Active humps resulting from active dissolution of nickel were obtained by creating the bared metal surfaces in thiosulphate solutions. The lower the Cr content the higher is the dissolution rate. The passive films formed on the bared metal surface were examined by ac impedance. Results suggest the formation of multi-layers oxide which were affected by active dissolution reactions during repassivation. (author).

Energy Technology Data Exchange (ETDEWEB)

Progress is reported on: radon barrier systems for uranium mill tailings; liner evaluation for uranium mill tailings; revegetation/rock cover for stabilization of inactive U-tailings sites; and application of long-term chemical biobarriers for uranium tailings.

CERN Document Server

Safe management of wastes from the mining and milling of Uranium and Thorium ores

International Nuclear Information System (INIS)

Studied are the mechanical properties of welded joints and heat affected zones of the Kh8N10T steel and OT4 and VT1-2 titanium alloys on welding in Ar+deltaF_6 and Ar+CCl_2F_2 mixtures contributed to a decrease of porosity. Tensile and impact tests of welded joints have revealed that additions of sulfur hexafluoride into argon causes a decrease of impact strength in titanium alloy when the tensile strength does not depend on the composition of a halogen-containing atmosphere. Freon (CCl_2F_2) additions decrease only slightly the impact strength of the investigated alloys.

Energy Technology Data Exchange (ETDEWEB)

A method for the determination of different ''bare'' characteristics of the one-particle motion and one-particle basis in magic nuclei is described. The method is based on separating out the mixing with phonons from the phenomenological one-particle characteristics. By means of a generalization of the procedure for localization of the mass operator, relations linking the bare and phenomenological characteristics are obtained. The radial dependence of these characteristics in finite nuclei and the influence of the quasiparticle--phonon interaction on the phenomenological characteristics are studied. Calculations are performed for the neutrons in /sup 208/Pb.

Energy Technology Data Exchange (ETDEWEB)

Simulated atmospheric corrosion studies were performed to determine the corrosion protection provided by galvanized zinc coatings on depleted uranium, U-0.75 Ti alloy, and U-6 Nb alloys. The accelerated ASTM tests consisted of exposing the galvanized samples to aqueous and aqueous chloride environments. The test results showed that anodic protection was provided by the electronegative zinc coatings on uranium and uranium alloys. Treating zinc with chromate conversion coatings also provided more protection.

International Nuclear Information System (INIS)

The report is divided into six working group discussions on the following subjects: 1) Chemical and physical mechanisms in the formation of uranium mineralization, geochronology, isotope geology and mineralogy; 2) Sedimentary basins and sandstone-type uranium deposits; 3) Uranium in quartz-pebble conglomerates; 4) Vein and similar type deposits (pitchblende); 5) Other uranium deposits; 6) Relation of metallogenic, tectonic and zoning factors to the origin of uranium deposits. Each working group paper contains a short introductory part followed by a discussion by the working group members.

International Nuclear Information System (INIS)

The results of calculational comparative study into radiotoxicity and residual power release time dependences for spent uranium-plutonium and thorium-uranium nuclear fuels from the WWER-1000 reactors during ling- time (up to 300 thousand years) storage are discussed. It is shown that the total radiotoxicities for actinides from uranium, uranium-plutonium and thorium-uranium spent fuels at storage period begin amount to 5.2 x 10"1"4, 1.3 x 10"1"5 and 1.5 x 10"1"4 kg of water per 1 t of discharged fuel, respectively. Radiotoxicity of actinides in uranium-plutonium fuel is revealed to be by the factor of 2.5 greater than that for ordinary uranium fuel because of greater accumulation of "2"3"9Pu, "2"4"0Pu, "2"4"1Pu and "2"4"4Cm. Radiotoxicity of actinides for thorium-uranium fuel calculated taking into account "2"3"4U is ...

International Nuclear Information System (INIS)

Aerodynamic sound derived from bluff bodies can be considerably reduced by flow control. In this paper, the authors propose a new method in which porous material covers a body surface as one of the flow control methods. From wind tunnel tests on flows around a bare cylinder and a cylinder with porous material, it has been clarified that the application of porous materials is effective in reducing aerodynamic sound. Correlation between aerodynamic sound and aerodynamic force fluctuation, and a surface pressure distribution of cylinders are measured to investigate a mechanism of aerodynamic sound reduction. As a result, the correlation between aerodynamic sound and aerodynamic force fluctuation exists in the flow around the bare cylinder and disappears in the flow around the cylinder with porous material. Moreover, the aerodynamic force fluctuation of the cylinder with porous material is less than that of the bare cylinder. ...

International Nuclear Information System (INIS)

To compare clinical effectiveness of Viabil-covered stents versus uncovered metallic Wallstents, for palliation of malignant jaundice due to extrahepatic cholangiocarcinoma, 60 patients were enrolled in a prospective and randomized study. In half of the patients a bare Wallstent was used, and in the other half a Viabil biliary stent. Patients were followed up until death. Primary patency, survival, complication rates, and mean cost were calculated in both groups. Stent dysfunction occurred in 9 (30%) patients in the bare stent group after a mean period of 133.1 days and in 4 (13.3%) patients in the covered stent group after a mean of 179.5 days. The incidence of stent dysfunction was significantly lower in the covered stent group (P = 0.046). Tumor ingrowth occurred exclusively in the bare stent group (P = 0.007). Median survival was 180.5 days for the Wallstent and 243.5 days for the Viabil group (P = 0.039). Complications ...

British Library Electronic Table of Contents (United Kingdom)

Riparian agricultural environments in eastern Australia are widely used for cattle grazing, but are also preferred habitat for native, soil-disturbing mammals such as the bare-nosed wombat (Vombatus ursinus). We examined the effects of mound construction by wombats, and track development by cattle and wombats, on soil displacement in a riparian landscape at high and low levels of cattle usage. Splash erosion was measured on mounds and inter-mounds with splashboards, and changes in the profiles of cattle-wombat tracks were assessed using a profilemeter. Twice as much soil was detached by splash erosion from mounds than inter-mounds, irrespective of cattle usage, and about three-times more coarse sand and 40% more fine sand was detached from mounds and inter-mounds at the high cattle sites. ...

Energy Technology Data Exchange (ETDEWEB)

Tetracycline in solution of benzyl alcohol was used as an extracting agent to separate uranium from interfering elements in the determination of uranium and of isotopic ratio sup(235)U/sup(238)U by neutron activation analysis. Separation gives a recovery of 97% for uranium and the interferences from matrices of pitchblende and monazite are eliminated.

International Nuclear Information System (INIS)

... Hayashi, Shinichiro Japan Atomic Energy Agency, Tokai, Ibaraki (Japan)

International Nuclear Information System (INIS)

Daily exposures of adult beagle dogs to inhaled radon daughters and to uranium ore dust for 4-1/2 to 6 yr have produced respiratory tract carcinomas, at similar cumulative working level months (WLM) of exposures to those which induced carcinomas in uranium miners. Biological data from the beagle-dog experiments can therefore be used for prediction of carcinogenic risk under changing exposure conditions in future uranium miners.

International Nuclear Information System (INIS)

The potential use of uranium in the field of catalysis is presented in the first part of this paper. Numerous applications of uranium binary oxides, as well as mixed oxides, are reviewed with a special emphasis on the role of U-Sb-O catalysts in selective oxidation (and ammoxidation) processes. Attempts are made to correlate the electronic structure of uranium, and especially the role that 5f electrons play in bonding, with its promising catalytic properties. In the second part, new data are given for uranium-bismuth mixed oxides in the catalytic oxidation of CO by O_2. Kinetic tests performed in a flow microreactor allow a mechanism to be proposed that involves the direct participation of lattice oxygen of the catalyst in the chemical process (redox mechanism). The high activity can be related to the ability of uranium to change reversibly its oxidation state. (author).

International Nuclear Information System (INIS)

It is essential that alumina used for manufacturing electronic devices should contain an extremely low level of alpha-radiation. The principal source of alpha-radiation in alumina is uranium, a minor source being thorium. Uranium in bauxite dissolves into the liquor in the digestion process and is fixed to the red mud as the desilication reaction progresses. A part of uranium remaining in the liquor precipitates together with aluminum hydroxide in the precipitation process. The uranium content of aluminum hydroxide becomes lower as the precipitation velocity per unit surface area of the seed becomes slower. Organic matters in the Bayer liquor has an extremely significant impact on the uranium content of aluminum hydroxide. Aluminum hydroxide free of uranium is obtainable from the liquor that does not contain organic matters.

Science.gov (United States)

Investigations were conducted at Los Alamos National Laboratory to quantify the extent of migration of depleted uranium away from firing sites. Extensive sampling of air particles, soil, sediment, and water was conducted to establish the magnitude of uranium contamination throughout one watershed. The uranium source term was estimated, and mass balance calculations were performed to compare the percentage of migrated uranium with original expenditures. Mass balance calculations can be powerful in identification of the extent of waste migration and used as an aid in planning future waste investigations.

International Nuclear Information System (INIS)

The near-term availability of domestic and selected foreign uranium resources for use by United States electric utilities is considered in light of projected geopolitical and socioeconomic considerations. No attempt is made to analyze the impact on domestic uranium supply of inflation or cost-price considerations, the introduction of the breeder reactor, limitations in enrichment capacity, or the presently expanding uranium inventory. All data are current as of mid-1980. The period with which this research is concerned is 1980-1995. It is concluded that the United States must promote responsible, environmentally acceptable uranium resource exploration and development, if this nation is to remain self sufficient in this necessary energy commodity.

Energy Technology Data Exchange (ETDEWEB)

We report on the fouling of Focused Ion Beam (FIB)-fabricated silicon oxide nanopores after exposure to tap water for two weeks. Pore clogging was monitored by Scanning Electron Microscopy (SEM) on both bare silicon oxide and chemically functionalized nanopores. While fouling occurred on hydrophilic silicon oxide pore walls, the hydrophobic nature of alkane chains prevented clogging on the chemically functionalized pore walls. These results have implications for nanopore sensing platform design.

Energy Technology Data Exchange (ETDEWEB)

Corona from bare conductors of electrical overhead power lines is studied in this article. Its origin, as well as, its bad influences over communication systems are both studied, yet. Line`s models are defined, in order to be able the examination of Corona on line`s cables. Formulas for the surface electrical gradient calculations are shown. (author) 2 refs.

UK PubMed Central (United Kingdom)

BackgroundPaclitaxel-eluting stents decrease angiographic and clinical restenosis following percutaneous coronary intervention compared to bare metal stents. TAXUS Element is a third-generation...Full Text Available

International Nuclear Information System (INIS)

The total amount of uranium dissolved in seawater at a uniform concentration of 3 mg U/m3 in the world's oceans is 4.5 billion tons. An adsorption method using polymeric adsorbents capable of specifically recovering uranium from seawater is reported to be economically feasible. A uranium-specific nonwoven fabric was used as the adsorbent packed in an adsorption cage 16 m2 in cross-sectional area and 16 cm in height. We submerged three adsorption cages in the Pacific Ocean at a depth of 20 m at 7 km offshore of Japan. The three adsorption cages consisted of stacks of 52 000 sheets of the uranium-specific non-woven fabric with a total mass of 350 kg. The total amount of uranium recovered by the nonwoven fabric was >1 kg in terms of yellow cake during a total submersion time of 240 days in the ocean.

Science.gov (United States)

Oxydes d'Uranium et de Plutonium. J. Nucl. Mat., vol. 33, no. 1, Oct. 1969, pp. 40-51. 21. Hall, A. R.: Elastic Moduli and Internal Friction of Some Uranium ...

International Nuclear Information System (INIS)

Determination of the specific surface of uranium oxides: UO_2 and U_3O_8 using a simplified equation derived from the Brunauer, Emmett and Teller theory. The method is suitable for samples having a surface between 6 to 50 m"2.

International Nuclear Information System (INIS)

This report describes a field-test program to determine the effectiveness of a polymeric wall sealant to reduce the escape of naturally occurring radioactive gas radon from the walls of an underground uranium mine into the ventilation air.

Energy Technology Data Exchange (ETDEWEB)

The Lander Quadrangle, Wyoming, was evaluated to a depth of 1500 m to identify environments and delineate areas that exhibit characteristics favorable for the the occurrence of uranium deposits. The evaluation used criteria established for the National Uranium Resources Evaluation program. The methods of surface investigations included evaluation of aerial radiometric and hydrogeochemical stream-sediment reconnaissance data, verification of some reported uranium occurrences, and general field geology with rock, water, and sediment sampling. The subsurface evaluation was accomplished through the use of 230 various oil-well logs. The results of this investigation identified three environments favorable for sandstone uranium deposits in Eocene fluvial sediments. These environments are within the Battle Spring and upper Fort Union Formations of the northern Great Divide Basin and within the Wind River and ...

UK PubMed Central (United Kingdom)

The storage and distribution of copper, cadmium, and uranium and their effects on ionic contents in roots and shoots of Azolla filiculoides has been studied by x-ray microanalysis....Full Text Available

Energy Technology Data Exchange (ETDEWEB)

The desorption of uranium from the granular titanium-activated carbon composite adsorbent (concentration of uranium: 25.5 mg/l-Ad), which adsorbed uranium from natural sea water, was examined by the column process with acidic eluent at room temperature. The column operation was able to be carried out without destruction of the granular adsorbent by the generation of the carbon dioxide, and free from disturbance of the eluent flow by precipitate of calcium sulfate dihydrate with sulfuric acid eluent. The amount of acid consumption by the adsorbent was 0.87 eq/l-Ad. The alkaline earth metals were eluted in the range of elution volume below 2l/l-Ad, whereas uranium, iron, and titanium were eluted above 2l/l-Ad. Therefore, uranium was separable from the alkaline earth metals which were adsorbed in the most quantity in the adsorbent. In the range of elution volume 2 to 12l/l-Ad, the ...

International Nuclear Information System (INIS)

A method to reduce the fuel composition heterogeneity effect on the core performance parameters has been studied for the DUPIC fuel which is made of spent pressurized water reactor (PWR) fuels by a dry refabrication process. This study focuses on the reactivity control method which uses either slightly enriched, depleted, or natural uranium to minimize the cost rise effect on the manufacturing of DUPIC fuel, when adjusting the excess reactivity control by slightly enriched and depleted uranium, reactivity control by natural uranium for high reactivity spent PWR fuels, and reactivity control by natural uranium for linear reactivity spent PWR fuels. The results of this study have shown that the reactivity control by slightly enriched and depleted uranium, all the spent PWR fuels can be utilized as the DUPIC fuel and the fraction of fresh uranium feed is 3.4% on an ...

International Nuclear Information System (INIS)

... Oceanographic Institution, Mass. (USA) v. 8 p. 439-442. abundance

Energy Technology Data Exchange (ETDEWEB)

Radiological hazard in uranium mining and milling operations are primarily due to exposure to external beta and gamma radiation as well as to airborne radionuclides which consist of radon and its short-lived daughter products. In May 1981 a radiological survey programme was performed in order to make a general assessment of the radiation hazards associated with the uranium mines and the Uranium Pilot Plant operated by the M.T.A. Institute in the Koprubasi district of the Manisa province. In this paper a preliminary radiological risk evaluation attempt is presented based on the radiation and radioactivity measurements performed in this district in May 1981.

International Nuclear Information System (INIS)

The purpose of the present research is to find a suitable technique to measure trace amounts of uranium and thorium and to determine the surface #alpha#-flux in silicon compound (SiO) used for fabrication of integrated circuit packaging materials. Among several commonly-used detecting techniques, it was found that neutron activation analysis (NAA) was most promising. The results from NAA show a large difference in uranium and thorium concentrations when cadmium and boron carbide shields are used, whereas #alpha#-flux measurements show a low #alpha#-activity, which corresponds to the trace amounts of uranium and thorium expected to be present in these materials. (author) 13 refs.; 6 figs.

Energy Technology Data Exchange (ETDEWEB)

Selected samples of waste microbial biomass originating from various industrial fermentation processes and biological treatment plants have been screened for biosorbent properties in conjunction with uranium and thorium in aqueous solutions. Biosorption isotherms have been used for the evaluation of biosorptive uptake capacity of the biomass which was also compared to an activated carbon and the ion exchange resin currently used in uranium production processes. Determined uranium and thorium biosorption isotherms were independent of the initial U or Th solution concentration. Solution pH affected the exhibited uptake. 24 refs.

International Nuclear Information System (INIS)

Heyuan mineralization belt is a structure-magmatic activities belt which is charcterized by strong plastic deformation and shearing. The squeeze (overthrust) structure is formed early. Later stretch produced slide shovel-shaped normal fault which control the red basin and uranium mineralization. Comprehensive study shows that this area is of favorable uranium metallogenic condition due to the rich uranium source and higher degree of geology work, it is a target for the new round resources exploration. (authors)

International Nuclear Information System (INIS)

A series of experimental measurements of the yield of O_3 in nuclear-induced O_2 and O_2-SF_6 discharges are reported. The discharges were created by bombardment with energetic particles from the "1"0B(n,#alpha#)"7Li reaction. Continuous irradiation at dose rates of 10"1"5--10"1"7 eV cm"-"3 s"-"1 and pulsed irradiation (--10 ms FWHM) at a peak dose rate of --10"2"0 eV cm"-"3 s"-"1 were conducted. At the lower dose rates, the addition of SF_6 generally increased the ozone yield due to the slowing of ozone destruction by negative oxygen and ozone ions. In contrast, at the high dose rates, the ozone concentration decreased due to SF_6 suppression of atomic oxygen formation by ion--ion recombination. A numerical model was developed and tested against experimental conditions. This model indicates that the steady-state ozone concentration was limited by the reaction O"-_3+O_3#->#2O_2+O"-_2 with a rate coefficient of --1 x 10"-"1"2 cm"3 s"-"1. In addition to dose rate effects, pressure and ...

International Nuclear Information System (INIS)

Methods of preparation, stability in solutions and in the solid phase, composition of orthophosphate crystallohydrates and condensed uranyl- and uranium (4) phosphates, are considered. Structures of these compounds are discussed; it is shown that they are steric polymers with an uranylphosphate framework. The problem of phosphate-anion polymerization in the process of thermal decomposition is discussed. It is established that condensed uranyl polyphosphates are not stable during storage, capable of degradation, its degree increasing with the phosphate chain length and uranium content.

International Nuclear Information System (INIS)

Daily exposures of adult beagle dogs to inhaled radon daughters plus uranium ore dust, with and without concurrent cigarette smoking, for 2 to 5-1/2 yr have produced massive pulmonary fibrosis and severe emphysema. The cumulative exposure doses are similar to those associated with a 5-fold or greater increase in death rate of uranium miners due to chronic respiratory insufficiency, including pneumoconiosis, pulmonary fibrosis, and emphysema.

Energy Technology Data Exchange (ETDEWEB)

Guidelines for uranium residual radioactive material in soil were derived for the B&T Metals Company site in Columbus, Ohio. This site has been identified for remedial action under the US Department of Energy`s (DOE`s) Formerly Utilized Sites Remedial Action Program (FUSRAP). Single-nuclide and total-uranium guidelines were derived on the basis of the requirement that following remedial action, the 50-year committed effective dose equivalent to a hypothetical individual living or working in the immediate vicinity of the site should not exceed a dose constraint of 30 mrem/yr for the current use and likely future use scenarios or a dose limit of 100 n-mrem/yr for less likely future use scenarios. The DOE residual radioactive material guideline computer code, RESRAD, was used in this evaluation. RESRAD implements the methodology described in the DOE manual for establishing residual radioactive material guidelines. Three scenarios were ...

Energy Technology Data Exchange (ETDEWEB)

Biosorption of elements is a little understood phenomenon exhibited by some types of even nonliving microbial biomass. A common fungus Rhizopus arrhizus has been reportd to take up uranium from adqueous solutions to the extent of 180 mg U/sup 6 +//g. The mechanism of uranium sequestering by this type of biomass was studied by using experimental techniques such as electron microscopy, x-ray energy dispersion analysis, IR spectroscopy, and supporting evidence was obtained for a biosorption mechanism consisting of at least three processes. Uranium coordination and adsorption in the cell-wall chitin structure occur simultaneously and rapidly whereas precipitation of uranylhdroxide within the chitin microcrystalline cell-wall structure takes place at a lower rate. Interference of Fe/sup 2/ and Zn/sup 2 +/ coions with uranium biosorption is indicated.

Energy Technology Data Exchange (ETDEWEB)

A flowing bed kiln is a gas-solid reactor used in the civil nuclear fuel cycle for the successive conversion of uranium trioxide (UO{sub 3}) into uranium dioxide (UO{sub 2}) and then into uranium tetrafluoride (UF{sub 4}). A numerical model is developed which simulate the behaviour of this reactor in permanent regime. This model describes the physico-chemical phenomena involved, and combines a mechanistic approach in the vertical area of the kiln (resolution by the finite volumes method) and a systemic approach in the horizontal area, like in the model of cascade mixers. The first results have been obtained for reference operating conditions of the industrial kiln. Some possible improvements of the optimum temperature progression inside the kiln are evoked. (J.S.)

Science.gov (United States)

A process is described for the recovery of uranium values from phosphoric acid utilizing an alkyl pyrophosphoric acid (Appa) primary extractant. After extracting the uranium from the phosphoric acid, the appa extractant is deactivated by heating and the uranium values stripped into a phosphoric acid strip solution containing ferric ion as a salting agent. The uranium values may then be re-extracted directly from this stripping solution without adjustment of its concentration into a dialkyl phosphoric acid trialkyl phosphine oxide synergistic extractant from which a relatively pure yellow cake is precipitated. A new procedure for preparing the requisite appa primary extractants is also disclosed.

CERN Document Server

Three-flavor lattice QCD simulations and two-loop perturbation theory are used to make the most precise determination to date of the strange-, up-, and down-quark masses, $m_s$, $m_u$, and $m_d$, respectively. Perturbative matching is required in order to connect the lattice-regularized bare- quark masses to the masses as defined in the \\msbar scheme, and this is done here for the first time at next-to-next-to leading (or two-loop) order. The bare-quark masses required as input come from simulations by the MILC collaboration of a highly-efficient formalism (using so-called ``staggered'' quarks), with three flavors of light quarks in the Dirac sea; these simulations were previously analyzed in a joint study by the HPQCD and MILC collaborations, using degenerate $u$ and $d$ quarks, with masses as low as $m_s/8$, and two values of the lattice spacing, with chiral extrapolation/interpolation to the physical masses. With the new perturbation theory ...

Energy Technology Data Exchange (ETDEWEB)

From 1980 to 1993, the domestic production of uranium declined from almost 44 million pounds U{sub 3}O{sub 8} to about 3 million pounds. This retrenchment of the U.S. uranium industry resulted in the permanent closing of many uranium-producing facilities. Current low uranium prices, excess world supply, and low expectations for future uranium demand indicate that it is unlikely existing plants will be reopened. Because of this situation, these facilities eventually will have to be decommissioned. The Uranium Mill Tailings and Radiation Control Act of 1978 (UMTRCA) vests the U.S. Environmental Protection Agency (EPA) with overall responsibility for establishing environmental standards for decommissioning of uranium production facilities. UMTRCA also gave the U.S. Nuclear Regulatory Commission (NRC) the responsibility for licensing and ...

International Nuclear Information System (INIS)

Spent oxide fuels are reduced in a molten salt of CaCl_2-CaF_2 to convert them into metals, then melted in an Fe-U bath disposed in an electrolytic refining vessel and brought into contact with molten Mg, to extract transuranium elements and rare earth elements contained in the Fe-U bath as metals in the molten Mg. Then molten Mg is removed and the residue is brought into contact with KCl-LiCl molten salt and electrolyzed using the Fe-U as an anode. Then, uranium is recovered by deposition on an iron cathode disposed in chloride electrolytes of the electrolytic refining vessel. Uranium and transuranium elements can be thus separated and, for example, depleted uranium for use in blanket fuels can be recovered easily. This can greatly reduce the temporary storage amount of depleted uranium, to eliminate requirement for a large-scaled facility used exclusively for storing uranium and ...

CERN Document Server

A fundamental and very well studied region of the Erd\\"os-R\\'enyi process is the phase transition at n/2 edges in which a giant component suddenly appears. We examine the process beginning with an initial graph. We further examine the Bohman-Frieze process in which edges between isolated vertices are more likely. While the positions of the phase transitions vary, the three processes belong, roughly speaking, to the same universality class. In particular, the growth of the giant component in the barely supercritical region is linear in all cases.

Energy Technology Data Exchange (ETDEWEB)

The marine ram-type blowout preventer deployed from an offshore drilling rig has one serious disadvantage, its inaccessibility. A development to promote reliability of the subsea ram-type preventer and reduce the excess running and pulling to charge out rams, is the variable bare ram (VBR). Unlike the standard ram, the VBR has the ability to pack off a range of pipe sizes. Interest in VBR's has been revived and research and development in this equipment goes on at each of three manufacturer's facilities in Houston.

International Nuclear Information System (INIS)

A simple and rapid laser fluorometric determination of trace and ultra trace level of uranium in a wide variety of low uranium content materials like soil, basic and ultra basic rocks, plant ash, coal fly ash and red mud samples is described. Interference studies of some common major, minor and trace elements likely to be present in different geological materials on uranium fluorescence are studied using different fluorescence enhancing reagents like sodium pyrophosphate, orthophosphoric acid, penta sodium tri-polyphosphate and sodium hexametaphosphate. The accurate determination of very low uranium content samples which are rich in iron, manganese and calcium, is possible only after the selective separation of uranium. Conditions suitable for the quantitative single step extraction of 25 ng to 20 #mu#g uranium with tri-n-octylphosphine oxide and single step ...

Energy Technology Data Exchange (ETDEWEB)

A trans-uranium (TRU) fuel should be manufactured and loaded in transmutation systems in order to transmute the long-lived TRU nuclides into short-lived ones. However, since all of the TRU nuclides are not completely transmuted in one cycle lifetime in transmutation systems, the spent TRU fuel has to be treated to recover the long-lived radionuclides or fuel matrix materials. One concept to manufacture TRU fuel for transmutation is to recover uranium from TRU and molten salt. If this type of fuel is adopted for transmutation, uranium could also be an objective material to be recovered and recycled. Since electrowinning is a promising technology to be employed for the recovery of uranium from fuel materials, some experimental work of electrowinning using anode of Cd-Li alloy was carried out in this study. The basic salt chosen was a mixture of LiCl-KCl which has an eutectic point at 357 .deg. C.

Energy Technology Data Exchange (ETDEWEB)

The solubilities of plutonium and uranium have been determined for alkaline salt solutions having compositions which bound those which will be processed in the In-Tank Precipitation (ITP) process. Loadings of plutonium and uranium onto monosodium titanate (MST) have been determined at temperatures bounding those expected to occur during ITP and using a salt solution which was determined to have the maximum solubility for uranium and plutonium. Fissile loadings increase with decreasing amounts of MST in contact with the salt solutions saturated in plutonium and uranium. At MST concentrations bounding those which are planned for the ITP process, expressions for the maximum loadings (wt %) are determined to be 0.29 - 0.20x[MST] for plutonium and 1.8 - 0.29x[MST] for uranium, where [MST] is the concentration of MST in grams/liter. These expressions are valid over the range of MST ...

International Nuclear Information System (INIS)

High-resolution sequence stratigraphy taking base-level cycles as interface of reference was developed rapidly in recent years. Its greatest predominance lies in that it can be applied to multi-controled continental sedimentary basins and can effectively improve accuracy and distinguishability of sequence stratigraphy analysis. Principles of base-level cycles can also be applied to the research and practice of the exploration and exploitation of sandstone-type uranium deposits as they control the spatial distribution, porosity, the permeability and the sealing ability of sandstone and mudstone, and stacking patterns of strata configuration. Taking Dongsheng uranium deposits as an example, the application of base-level cycles to exploration and exploitation of sandstone uranium deposits was analyzed. It is suggested that favorable strata framework of sandstone and mudstone was developed very well in the fluctuation of ...

Energy Technology Data Exchange (ETDEWEB)

The technology developed here will exploit the ability of microorganisms to remove dissolved metals from aqueous solutions. Microbial sorbents for uranium will be immobilized biosorbents will be deployed ex situ within flow-through reactors for the continuous or semicontinuous treatment of recovered wastewaters. The proposed technology will primarily be applied within a pump-and-treat process using immobilized biosorbents for the large-scale, long-term remediation of uranium-laden surface water or groundwater impoundments (environmental restoration). The technology may be equally useful as an ``end-of-pipe`` treatment of process effluents (waste management). Successful operation of this process will achieve immobilization of the targeted waste and accompanying volume reduction.

Energy Technology Data Exchange (ETDEWEB)

Study of the rate of dissolution in simulated lung fluid of uranium from 3 different ore matrices and from refined uranium dioxide in an essentially all teflon extraction apparatus; the rate of dissolution of thorium from a nickel metal/2 percent thoria mixture; the effect of neutron irradiation of the studied materials upon the dissolution rates; and the adsorptions of the radioisotope tracers barium 133 (substitute for radium), lead 203 and thorium 234 upon the extraction system components.

Science.gov (United States)

Major contributions during this contract period have been in developing an analytical procedure for Pu measurement, and in applying the developed procedures to determining the plutonium concentration and distribution in coral from the Bikini Atoll. In conjunction with these contributions, measurements using the fission-track method have been made of the uranium distribution and concentrations in several carbonate samples from drill cores obtained from the Runit Island Enewetak Atoll. Petrographic studies on these drill core samples have been made to correlate the uranium data with the mineralogical data. (auth)

Energy Technology Data Exchange (ETDEWEB)

The Purex process and the fluorescence spectrometry are first recalled, then uranyl fluorescence is studied in a pure nitric medium without other elements to establish a theoretical model, allowing the description of uranium fluorescence signal with a general equation. The influence of different parameters (temperature, inhibitors, dynamic quenching of iron and cerium) is investigated to develop the model. A quantitative analysis method without addition of reagents is proposed to validate the model.

Science.gov (United States)

The US National Council on Radiation Protection and Measurements, in collaboration with the International Commission on Radiological Protection, has been developing a biokinetic and dosimetric model for radionuclide-contaminated wounds. The finalised model is described briefly in this paper, together with the scientific basis and application. The multicompartment model uses first-order linear biokinetics to describe the retention and clearance of a radionuclide deposited in a wound site using seven default retention categories. Examples using plutonium nitrate in colloidal form and uranium in metal fragments show the behaviour of the less soluble forms of radionuclides in wounds, in which long-term retention is predicted. Using uranium as an example, the wound model is coupled to a uranium International Commission on Radiological Protection systemic model to predict urinary excretion patterns for different physicochemical ...

International Nuclear Information System (INIS)

... p. 93 Russian Federation Rovnyj, SI Ufimtsev, VP Shevtsev, PP Nedelina,

Energy Technology Data Exchange (ETDEWEB)

Thin passive layers of uranium nitride were formed by nitriding pure metallic uranium in non-equilibrium, low pressure radio-frequency plasma of nitrogen. Plasma nitriding at low substrate temperature of 230 C-250 C was found to cause the formation of adherent layers of uranium sesquinitride ({alpha}-U{sub 2}N{sub 3}) which provide a considerable protection against hydrogen attack. The characteristics of these passivation layers were determined by X-ray diffraction and Auger electron spectroscopy. The incipient hydriding kinetics of the plasma-treated samples were compared with those of untreated and nitrogen-ion implantation ones, utilizing a hot-stage microscope that was monitored continuously with a TV camera and videotape. (orig.)

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Chronic exposure to uranium compounds such as UO{sub 2} and U{sub 3}O{sub 8} led to the development of a methodology, based on the recommendation of ICRP, involving four main steps: the measurement of the uranium concentration and the particle size distribution at the workstation, the assessment of physico-chemical properties of the compound, the study of in-vitro solubility using a chemical test and the monitoring of workers. Results and comments on UO{sub 2} and U{sub 3}O{sub 8} are given. (author)

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Evaluations were done to determine conditions that could permit nuclear criticality with fissile uranium in low-level waste (LLW) facilities and to estimate potential radiation exposures to personnel if there were such an accident. Simultaneous hydrogeochemical and nuclear criticality studies were done (1) to identity realistic scenarios for uranium migration and concentration increase at LLW disposal facilities, (2) to model groundwater transport of uranium and subsequent concentration via sorption or precipitation, (3) to evaluate the potential for nuclear criticality resulting from potential increases in uranium concentration over disposal limits, and (4) to estimate potential radiation exposures to personnel resulting from criticality consequences. This paper presents the details of the radiation exposure calculations relying on the conditions as determined from the preceding studies detailed in a ...

International Nuclear Information System (INIS)

The methods are described of determining natural radionuclides, viz., thorium, uranium, radium, radon, polonium, actinium, and protactinium. The analysis is also described of ores, rocks, minerals, water, air. (M.D.).

British Library Electronic Table of Contents (United Kingdom)

By means of ab-initio electronic structure calculation and one-dimensional Boltzmann transport equation solution, we investigate the size dependent thermoelectric (TE) properties of n-type ZnO nanowires (NWs) and surface passivation effects. As demonstrated by our calculations, largest figure of merit ZT achievable in thin NWs is larger than that in wide NWs, whereas being restrained by higher demand of n-type doping. Moreover, bare NWs are superior in TE application comparing with the passivated. To compete with conventional TE materials, lattice thermal conductivity of ZnO NWs should be at least 2 orders of magnitude lower than bulk value.

British Library Electronic Table of Contents (United Kingdom)

Background: Mechanisms underlying the association between myocardial bridge (MB)-stenting and in-stent restenosis (ISR) are still unclear. Objective: To assess the impact of MB on ISR using intravascular ultrasound (IVUS). Methods: In the Harmonizing Outcomes with Revascularization and Stents in Acute Myocardial Infarction (HORIZONS-AMI) trial, 100 left anterior descending artery (LAD) culprit lesions (79 treated with paclitaxel-eluting stents [PES] and 21 treated with bare metal stents) were imaged with serial IVUS immediately postprocedure and at 13 months. Results: At baseline the LAD stent extended into the MB segment beyond the culprit lesion in seven patients (MB-stent group). In the remaining 93 patients the LAD stent was implanted only in the culprit lesion without extending into t...

International Nuclear Information System (INIS)

Nuclear astrophysics seeks for a possible explanation of the observed abundance distribution of various elements and their isotopes in the universe. Most of the relevant nuclear reactions take place in thermally equilibrium environments with bare nuclei, rather than accelerated and head-on colliding situations with low ionisation states of reactant atoms and molecules that are emulated in the laboratories. Moreover, the temperature of the astrophysical environments is quite often low compared to the centre-of-mass energy of the projectile nuclides, that is required for the reaction to be meaningfully investigated in the laboratory. Therefore, an extrapolation of the data on the reaction cross sections to very low energies and to extremely high density situations is generally called for, which are substantially altered every now and then for a number of astrophysically important reactions. The radioactive ion beams will provide us important data on some of those ...

CERN Document Server

The Goldstone-Brueckner perturbation theory is extended to incorporate in a simple way correlations associated with large amplitude collective motions in nuclei. The new energy expansion making use of non-orthogonal vacua still allows to remove the divergences originating from the hard-core of the bare interaction. This is done through the definition of a new Brueckner matrix summing generalized Brueckner ladders. At the lowest-order, this formalism motivates variational calculations beyond the mean-field such as the Generator Coordinate Method (GCM) and the Projected Mean-Field Method from a perturbative point of view for the first time. Going to higher orders amounts to incorporate diabatic effects in the GCM and to extend the projection technique from product states to well-defined correlated states.

International Nuclear Information System (INIS)

The electron-phonon spectral distribution function #alpha#"2(#omega#) F (#omega#) has been calculated for niobium. The electron energy bands and wave functions were obtained from a self-consistent augmented-plane-wave muffin-tin potential, and the electron-phonon matrix elements were evaluated using the so-called rigid-ion approximation. With this approximation it is found that #alpha#"2(#omega#) is constant over the whole energy spectrum. The electron-phonon mass enhancement has also been calculated for local regions of the Fermi surface and found to be anisotropic. The calculated local values of the enhancement do not agree with experimental values available for different orbits from de Haas--van Alphen measurements. The discrepancy seems to arise because the bare-rigid-ion matrix elements are relatively small between states with nearly pure l = 2 character.

CERN Document Server

In this article we present the complete resummation of the leading chirally-enhanced corrections stemming from gluino-squark, chargino-sfermion and neutralino-sfermion loops in the MSSM with non-minimal sources of flavor-violation. We compute the finite renormalization of fermion masses and the CKM matrix induced by chirality-flipping self-energies. In the decoupling limit Msusy>>v, which is an excellent approximation to the full theory, we give analytic results for the effective gaugino(higgsino)-fermion-sfermion and the Higgs-fermion-fermion vertices. Using these vertices as effective Feynman rules, all leading chirally-enhanced corrections can consistently be included into perturbative calculations of Feynman amplitudes. We also give a generalized parametrization for the bare CKM matrix which extends the classic Wolfenstein parametrization to the case of complex parameters lambda and A.

Energy Technology Data Exchange (ETDEWEB)

An apparatus is described for measuring the total hemispherical emittance of pipes of a length suitable for use in a prototype solar collector. The calorimetric method used requires measurements of the temperatures of the surface of the test pipe and of a concentric outer cylinder and measurement of the electrical power used to heat the test pipe. Measurements were made of the total hemispherical emittance of black chrome, nickel, and bare steel pipes as a function of temperature. The emittance of the black chrome surfaces increased significantly from an extrapolated value of about 0.1 at 25 deg C to values on the order of 0.3-0.4 at 300 deg C. The extrapolated values for black chrome agreed with measurements made using other techniques at room temperature. The results for the nickel-plated pipe agreed with total emittance calculated from spectral reflectance data.

Science.gov (United States)

Hydrogen molecule adsorption on the (0001) surface of double hexagonal closed packed americium has been studied in detail within the framework of density functional theory. Weak molecular hydrogen adsorptions were observed. The most stable configuration corresponded to a Hor2 approach molecular adsorption at the one-fold top site where the molecule's approach is perpendicular to a lattice vector. Adsorption energies and adsorption geometries for different adsorption sites will be discussed. The change in work functions, magnetic moments, partial charges inside muffin-tins, difference charge density distributions and density of states for the bare Am slab and the Am slab after adsorption of the hydrogen molecule will be discussed. Reaction barrier for the dissociation of hydrogen molecule will be presented. The implications of adsorption on Am 5f electron localization-delocalization will be summarized.

Energy Technology Data Exchange (ETDEWEB)

Biosorption of uranium by residual biomass from The Old Bushmill`s Distillery Co. Ltd., Bushmills, Co. Antrim, Northern Ireland, following exposure to short and intense electric pulses has been examined. The biomass was prepared from the distillery spent wash and consisted of non-viable yeast and bacterial cells. As shown previously, untreated biomass had a maximum biosorption capacity of 170 mg uranium/g dry weight biomass. When biosorption reactions were placed between two electrodes and exposed to electric pulses with field strengths ranging from 1.25-3.25 kV/cm at a capacitance of 25 {mu}F, biosorption increased from 170 mg of uranium to 275 mg uranium/g dry weight biomass. The data were obtained from biosorption isotherm analyses and taken as the degree of biosorption at residual uranium concentrations of 3 mM. In addition, when the capacitance of the electric pulses increased ...

Science.gov (United States)

In response to a need of the safeguards community, we have begun an evaluation effort to upgrade the recommended values of the prompt neutron emission multiplicity distribution, P/sub nu/ and its average value, nubar. This paper will report on progress achieved thus far. The evaluation of the uranium, plutonium, americium and curium nuclide's nubar values will be presented. The recommended values will be given and discussed. 61 references.

Energy Technology Data Exchange (ETDEWEB)

This paper reviews the mill flowsheet applied at the COMINAK uranium mill (Compagnie Miniere d'Akouta) in Niger. For ore treatment, it focuses on the major improvements to the operations using sulfonitric pugging and solids/liquid separation using belt filter double filtration after leaching. The precipitation circuits have been improved with molybdenum elimination through caustic washing of the yellow cake. (author)

International Nuclear Information System (INIS)

The optical properties of uranium monochalcogenides and monopnictides are discussed in terms of their electronic structure. A comparison is made with corresponding rare earth compounds. It is shown that there are close similarities to mixed valence CeN. the results support the occurrence of a dip in the density of d states near Esub(F), where the f density of states has its maximum. Empirical energy level schemes are derived which are found to agree with the existing information from XPS measurements and recent theories. (orig.).

Energy Technology Data Exchange (ETDEWEB)

This ISB in conjunction with the new TSRs, will provide the required basis for interim operation or restrictions on interim operations and administrative controls for the Facility until a SAR is prepared in accordance with the new requirements. It is concluded that the risk associated with the current operational mode of the Facility, uranium closure, clean up, and transition activities required for permanent closure, are within Risk Acceptance Guidelines. The Facility is classified as a Moderate Hazard Facility because of the potential for an unmitigated fire associated with the uranium storage buildings.

Energy Technology Data Exchange (ETDEWEB)

Niger is the second poorest country in the world but it has natural resources underground in the form of uranium ores deposits. This uranium is currently mined by two companies incorporated under Nigerian law: Somair and Cominak, operated by the principal shareholder Areva (through its subsidiary Cogema). After a presentation of Somair and Cominak key figures, this document details the working conditions and radiological protection, the environmentally friendly operations, the production traceability, the local economic development, the strengthening of the health care system and the development of the infrastructure. (A.L.B.)

Science.gov (United States)

An advanced experimental technique has been developed to simulate two-phase flow behavior in a light water reactor (LWR). The technique applies three kinds of methods; (1) use of sulfur-hexafluoride (SF6) gas and ethanol (C2H5OH) liquid at atmospheric temperature and a pressure less than 1.0MPa, where the fluid properties are similar to steam-water ones in the LWR, (2) generation of bubble with a sintering tube, which simulates bubble generation on heated surface in the LWR, (3) measurement of detailed bubble distribution data with a bi-optical probe (BOP), (4) and measurement of liquid velocities with the tracer liquid. This experimental technique provides easy visualization of flows by using a large scale experimental apparatus, which gives three-dimensional flows, and measurement of detailed spatial distributions of two-phase flow. With this technique, we have carried out experiments simulating two-phase flow behavior in a single-channel geometry, a ...

International Nuclear Information System (INIS)

The purpose of this study is to investigate the possibility of verifying depleted uranium (DU), natural uranium (NU), low enriched uranium (LEU) and high enriched uranium (HEU) by a developed digital gamma-gamma coincidence spectroscopy. The spectroscopy consists of two NaI(Tl) scintillators and XIA LLC Digital Gamma Finder (DGF)/Pixie-4 software and card package. The results demonstrate that the spectroscopy provides an effective method of "2"3"5U and "2"3"8U quantification based on the count rate of their gamma-gamma coincidence counting signatures. The main advantages of this approach over the conventional gamma spectrometry include the facts of low background continuum near coincident signatures of "2"3"5U and "2"3"8U, less interference from other radionuclides by the gamma-gamma coincidence counting, and region-of-interest (ROI) imagine analysis for uranium enrichment ...

International Nuclear Information System (INIS)

A numerical investigation of the mixing of gaseous uranium and hydrogen inside an open-cycle gas core nuclear rocket engine (spherical geometry) is presented. The gaseous uranium fuel is injected near the centerline of the spherical engine cavity at a constant mass flow rate, and the hydrogen propellant is injected around the periphery of the engine at a five degree angle to the wall, at a constant mass flow rate. The main objective is to seek ways to minimize the mixing of uranium and hydrogen by choosing a suitable injector geometry for the mixing of light and heavy gas streams. Three different uranium inlet areas are presented, and also three different turbulent models (k-var-epsilon model, RNG k-var-epsilon model, and RSM model) are investigated. The commercial CFD code, FLUENT, is used to model the flow field. Uranium mole fraction, axial mass flux, and radial mass flux ...

Energy Technology Data Exchange (ETDEWEB)

The use of borated plaster to isolate uranium (93.2 wt % /sup 235/U) metal was studied in a series of subcritical experiments with uranium metal cylinders (7.0 in. diam, 2.0 in. thick) and slabs (approx.1.4 x approx.5.4 x approx.10.1 in. dimensions). In the cylindrical experiments, the thickness of borated plaster was varied up to 10 in. and the subcriticality measured using the /sup 252/Cf-source-driven neutron noise analysis method. In the experiments with the uranium slabs, an array of slabs 3 wide and 8 high was assembled in steps to demonstrate the subcriticality of this array with 3.75-in.-thick borated plaster as an isolating material between all uranium slabs. In the slab experiments, both noise analysis and source neutron multiplication measurements were performed. Before assembly of the slab array the presence of boron in the plaster was verified by neutron transmission and gamma-ray ...

International Nuclear Information System (INIS)

In the present work, a rapid deposition anodic stripping voltammetry (ASV) for determination of uranium is presented. For this purpose, the uranyl hexacyanoferrate (K2UO2[Fe(CN)6]) is deposited electrochemically on a thin palladium-aluminum electrode (Pd-Al) from a UO22+ solution in the presence of K3Fe(CN)6. Then, the well stable (K2UO2[Fe(CN)6]) on the electrode was stripped by anodic differential pulse voltammetry for measuring the UO22+ ion concentration. The effect of operational parameters, including: concentration of K3Fe(CN)6, solution pH, deposition potential, and deposition time were studied. In optimum conditions, the calibration graph was linear in the concentration range 105-7 x 10-4 mol L-1 with a detection limit of 6.2 x 10-6 mol L-1. The influence of some concomitant ions in K2UO2[Fe(CN)6] formation was investigated. The proposed method was used for the rapid determination of uranium in some uranium mineral ...

International Nuclear Information System (INIS)

Full text: Semiconductor detectors coated with boron or lithium compounds have been studied for neutron detection for decades but, until recently, have been limited to thermal neutron detection efficiencies of less than 5%. We reported previously on development and simulation studies of perforated detectors whose perforations are filled with neutron-reactive material in order to produce higher detection efficiencies. Incorporation of bare and cadmium-backed detectors into battery-powered devices with low-power electronics enables us to produce compact personal neutron dosimeters that provide LED readout of counts, which can be related approximately to neutron dose. We report here on experimental studies with such compact devices; devices capable of direct readout in dose units are anticipated. The thermal and epithermal neutron flux densities from the tangential beam tube of the TRIGA Mark II reactor at Kansas State University were measured. Then, thermoluminescent ...

International Nuclear Information System (INIS)

In Japan, the Ningyo-toge uranium deposit was discovered in 1955, and the Tono deposit in 1962. Geology of these mines is different from that of other metal mines developed in Japan. Therefore, it appeared that some changes were required in the usual mining methods applied to existing metal mines to mine uranium ore in these deposits. At the Ningyo-toge mine, effective methods were studied for mining the ore, such as the room and pillar method, long-wall method, slicing method, and the hydraulic method; as a result, it was determined that a modified long-wall method is the most useful and practicable for recovering uranium ore from this underground sedimentary deposit. Applicatons of in-place and microbiological leaching to these deposits are being studied to secure mine safety and decrease mine pollution. Since 1959, when the Ningyo-toge mine went into operation, no hazards for workers nor any pollution of the environment ...

Energy Technology Data Exchange (ETDEWEB)

Inactive cells of Rhizopus arrhizus have been documented to exhibit a high thorium biosorptive uptake (170 mg/g) from aqueous solutions. The mechanism of thorium sequestering by this biomass type was investigated following the same method as for the uranium biosorption emchanism. The thorium sequestering mechanism appeared somewhat different from that of uranium. Experimental evidence is presented which indicates that, at optimum biosorption pH (4), thorium coordinates with the nitroge of the chitin cell wall network and, in addition, more thorium is adsorbed by the external section of the fungal cell wall. At pH 2 the overall thorium uptake is reduced. The kinetic study of thorium biosorption revealed a very rapid rate of uptake. Unlike uranium at optimum solution pH, Fe/sup 2 +/ and Zn/sup 2 +/ did not interfere significantly with the thorium biosorptive uptake capacity of R. arrhizus.

International Nuclear Information System (INIS)

This study started with a comprehensive and critical review of the published information of relevance to the different methods to produce uranium dioxide from raw materials. we have chosen this method 'flame denitration' or flame process to produce Uo_2. from its compounds, uranyl nitrate Uo_2 ( NO_3) _2 .6H_2o) prepared from raw uranium 'yellow cake'. This method in short produces uranium dioxide from aqueous uranyl nitrate by contacting the atomized liquid which has 40 #mu# in diameter with hot reducing gases (butane and oxygen mixture) till we obtain a suitable and yellow red colour light for the flame and this is a prof that there is carbon monoxide and hydrogen, the temperature of the reactor at is least 950 degree C.

International Nuclear Information System (INIS)

Using the Laser-Fluorescence technique, an investigation was made, adopting the standard mix method, on trace uranium concentrations in hot spring water and geothermal water from Lishan region, and in tap water from some major cities in Shanxi province. Totally 40 samples from 27 sites were investigated. Measurement showed that the tap water contains around 10"-"6 g/L of uranium, whose concentrations in both hot spring water and geothermal water are 10"-"5 g/L. Most of samples are at normal radioactive background level, some higher contents were determined in a few samples

International Nuclear Information System (INIS)

The design, construction and operation of a pilot plant are often important stages in the development of a project for the production of uranium concentrates. Since building and operating a pilot plant is very costly and may not always be required, it is important that such a plant be built only after several prerequisites have been met. The main purpose of this guidebook is to discuss the objectives of a pilot plant and its proper role in the overall project. Given the wide range of conditions under which a pilot plant may be designed and operated, it is not possible to provide specific details. Instead, this book discusses the rationale for a pilot plant and provides guidelines with suggested solutions for a variety of problems that may be encountered. This guidebook is part of a series of Technical Reports on uranium ore processing being prepared by the IAEA's Division of Nuclear Fuel Cycle and Waste Management. 42 refs, 7 figs, 3 tabs.

International Nuclear Information System (INIS)

From their genesis by weathering and sedimentation, bauxites, the principal aluminium ores, contain appreciable amounts of uranium and thorium. High resolution gamma spectrometry with a high purity germanium detector was used for an analysis of four industrially used bauxites from Gondama, Sierra Leone; Boke, Guinea; Weipa, Queensland, Australia; Gove, Northern Territory, Australia. Significant differences in uranium to thorium ratios and in activities of the uranium and thorium daughters were observed for the four bauxites. It was found that the bauxite from Gondama, Sierra Leone has an activity of only 10% compared with the others. Red mud tailings from such a bauxite may well be used as an additive to bricks, which is now illegal for normal red mud from more active bauxites. (author).

International Nuclear Information System (INIS)

Categorization is complete. Samples 11-3-1 (NSR-F-270409-01) and 11-3-2 (NSR-F-270409-02) are depleted uranium powders of moderate purity (#approx#65-80 % U). The uranium feed stocks for 11-3-1 and 11-3-2 have both experienced a neutron flux (as demonstrated by the presence of "2"3"2U). Sample 11-3-3 is indistinguishable from a natural uranium ore concentrate of moderate purity (#approx#70-80% U). Two anomalous objects (11-3-1-4 and 11-3-2-5) were found in the material during aliquoting. These objects might be valuable for route attribution.

International Nuclear Information System (INIS)

Studies of asphalt emulsion sealants have demonstrated that the sealants are effective in containing radon and other potentially hazardous material within uranium tailings. The laboratory and field studies have further demonstrated that radon exhalation from uranium tailings piles can be reduced by greater than 99% to less than background levels. Field tests at the tailings pile in Grand Junction, Colorado confirmed that an 8-cm admix seal containing 22 wt % asphalt could be effectively applied with a cold-mix paver. Other techniques were successfully tested, including a soil stabilizer and a hot, rubberized asphalt seal that was applied with a distributor truck. After the seals were applied and conpacted, overburden was applied over the seal to protect the seal from ultraviolet degradation. 14 figures.

Energy Technology Data Exchange (ETDEWEB)

This book is based on a new method published in U.S. Geological Survey Circular 994 and is the second assessment made in accordance with the 1984 Memorandum of Understanding between the U.S. Department of the Interior and the U.S. Department of Energy. The first estimate was published as U.S. Geological Survey Open-File Report 80-2. The endowment estimates are reported for 26 areas in the following 1{degrees} {times} 2{degrees} guadrangles: Grand Canyon, Marble Canyon, Williams, Flagstaff, Prescott, Holbrook, and St. Johns, Ariz., and Cedar City, Utah. The total uranium endowment is about eight times larger than reported in 1980 by the Department of Energy. The Grand Canyon region has the potential of becoming the second most important domestic uranium producer after the most production San Juan Basin uranium region in New Mexico.

Energy Technology Data Exchange (ETDEWEB)

The ability of residual biomass from the thermotolerant ethanol-producing yeast strain Kluyveromyces marxianus IMB3 to function as a biosorbent for uranium has been examined. It was found that the biomass had an observed maximum biosorption capacity of 120 mg U/g dry weight of biomass. The calculated value for the biosorption maximum, obtained by fitting the data to the Langmuir model was found to be 130 mg U/g dry weight biomass. Maximum biosorption capacities were examined at a number of temperatures and both the observed and calculated values obtained for those capacities increased with increasing temperature. Decreasing the pH of the biosorbate solution resulted in a decrease in uptake capacity. When biosorption reactions were carried out using sea-water as the diluent it was found that the maximum biosorption capacity of the biomass increased significantly. Using transmission electron microscopy, uranium crystals were shown to be ...

International Nuclear Information System (INIS)

The production of the uranium mine Zirovski Vrh ceased in 1990. The main remaining problem of the remadiation are mine and mill tailings. The uranium mine Zirovski Vrh has one mill tailings site Borst and one waste pile Jazbec. According to the Act on protection against ionising radiation and nuclear safety which was adopted by the Parliament in 2002, they are classified as radiation facilities. Slovenian Nuclear Safety Administration (SNSA) is authorised for issuing a mandatory consent to mining work. The SNSA prepared the initial proposal of content of the safety report for the mine waste pile Jazbec. In 2005, according to the detailed content of this document, the public company Zirovski Vrh Ltd prepared the safety report which was examined by an authorised expert for radiation and nuclear safety. After a careful revision of the safety evaluation report, the consensus for mining work shall be issued by the SNSA. After finishing the mining ...

Energy Technology Data Exchange (ETDEWEB)

The storage of aluminum-clad fuel and target materials in the L-Disassembly Basin at the Savannah River Site for more than 5 years has resulted in extensive pitting corrosion of these materials. In many cases the pitting corrosion of the aluminum clad has penetrated in the uranium metal core, resulting in the release of plutonium, uranium, cesium-137, and other fission product activity to the basin water. In an effort to characterize the extent of corrosion of the Mark 31A target slugs, two unirradiated slug assemblies were removed from basin storage and sent to the Savannah River Technology Center for evaluation. This paper presents the results of the metallography and photographic documentation of this evaluation. The metallography confirmed that pitting depths varied, with the deepest pit found to be about 0.12 inches (3.05 nun). Less than 2% of the aluminum cladding was found to be breached resulting in less than 5% of the ...

Energy Technology Data Exchange (ETDEWEB)

The biological accumulation of heavy metals and cesium, strontium, and uranium in plants is discussed. The role of nutrient deficiencies and foliar treatments of manganese and iron compounds is described.

International Nuclear Information System (INIS)

A simple sample decomposition and laser fluorimetric determination of uranium at trace level is reported in certain refractory minerals, like ilmenite, rutile, zircon and monazite; environmental samples viz. soil and sediments; industrial waste materials, such as, coal fly ash and red mud. Ilmenite sample is decomposed by heating with ammonium fluoride. Rutile, zircon and monazite minerals are decomposed by fusion using a mixture of potassium bifluoride and sodium fluoride. Environmental and industrial waste materials are brought into solution by treating with a mixture of hydrofluoric and nitric acids. The laser induced fluorimetric determination of uranium is carried out directly in rutile, zircon and in monazite minerals and after separation in other samples. The determination limit was 1 #mu#g x g"-"1 for ilmenite, soil, sediment, coal fly ash and red mud samples, and it is 5 #mu#g x g"-"1 for rutile, zircon and monazite. The method is also ...

International Nuclear Information System (INIS)

Nuclear Fuel Plant (FCN) is a facility that produces fuel bundles of CANDU-6 type for the CANDU nuclear power plant. Only natural and depleted uranium in bulk and itemized form are present as nuclear materials in this facility. Uranium and wastes from the plant are handled, processed, treated and stored throughout the entire facility. The nuclear materials with natural and depleted uranium are entirely under nuclear safeguards. The amount of uranium present in the plant in different forms and activities together with zircaloy, beryllium and other hazardous substances, wastes, explosive materials at high temperatures, etc. lead to special measures undertaken by Nuclear Safety Department (DNS) to ensure nuclear safety. Different aspects of safety are continuously monitored in the plant: operational safety, industrial safety, radiological safety, labour safety, informational safety. The emergency ...

International Nuclear Information System (INIS)

Phosphoro-uraniferous deposit of Itataia is situated in Precambrian metamorphic terrains, into the litho-stratigraphic unit named Caico Complex. Regionally, the rocks are linearly folded, as a result of compressive tectonic that fits in the regmatic pattern. Rio Groairas' and Itatira's wrench faults form shearing couples in which the drag folds' climax are thrusting faults with axial plane dipping north. Uranium mineralization occurs into a phosphatic rock containing about 80% of collophane - 'collophanite - in association chiefly with marbles or feldsphatic rocks and gneisses. The ore (collophanite) occurs mainly as a stockwork, and it may be massive, (into big joints) or disseminated (impregnating the host rocks). Dark ore appears only in brecciated zones; it is richer in uranium content, but poorer in phosphorous. The highest grade ore is in a very fractured zone, associated to marbles. Supergene enrichment took place in this area. ...

International Nuclear Information System (INIS)

This regulatory guide describes methods acceptable to the NRC staff for calculating radon fluxes through earthen covers and for calculating the resulting minimum cover thickness needed to meet NRC and EPA standards. The guide also suggests methods for obtaining the various parameters used in calculating the radon fluxes and earthen cover thicknesses and suggests default values for certain parameters. This regulatory guide is applicable to active uranium tailings sites. The NRC staff is using the methods stated in this guide as a basis for review and concurrence of DOE remedial action plans for inactive sites. The guidance is intended to be used for calculating radon flux attenuation by earthen uranium mill tailings covers. The parameter values and examples presented are limited to earthen cover materials, but the diffusion theory and the methods presented are also applicable to man-made materials. Detailed supporting information for calculating ...

International Nuclear Information System (INIS)

A method of the correction for sample self attenuation used in segmented gamma scanner (SGS) is described. The method of calibration for assaying the uranium and plutonium contents of each category of heterogeneous process residues and wastes in nuclear facilities is studied. The effect of variable measurement parameter on measurement results is also studied. The measurement results of SGS assay is compared with that of the destructive assay (DA), which is aimed at evaluating SGS method for assaying uranium and plutonium content in process residues and wastes. The deviation of two assay results is 3.6%. The SGS assay results and DA assay results both are coincided well in error limits. Four category of heterogeneous process residues and wastes in nuclear facilities have assayed successfully in physical inventory. The uncertainty of measurement results for uranium and plutonium content in process residues and wastes is 5% ...

Energy Technology Data Exchange (ETDEWEB)

Magnetic coupling between two or more metal centers is an important facet of d- and f-block transition metal chemistry due to its implications in chemical bonding. With respect to actinide metals, magnetic coupling between polymetallic actinide centers is less well-known. Of the few documented examples, only one bimetallic uranium(V) complex, [(MeC{sub 5}H{sub 4}){sub 2}U]{sub 2}[{mu}-1,4-N{sub 2}C{sub 6}H{sub 4}] (1), has unequivocally demonstrated antiferromagnetic coupling. This complex employs a {pi}-conjugated 1,4-phenylenedimide ligand system which bridges the two f{sup 1}-metal centers and enables antiferromagentic coupling between unpaired f-e1ectrons residing in a {pi}-symmetry orbital. In this communication, we report the synthesis of a dimeric bis(imido) uranium(V) iodide complex and demonstrate with magnetic susceptibility measurements and density functional theory (DFT) calculations that the f{sup 1}-uranium ...

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A sensitivity study has been done to determine the composition of DUPIC fuel from the viewpoint of neutronics fuel design. The spent PWR fuel compositions were generated and fissile contents adjusted by blending fresh uranium after mixing two spent PWR fuel assemblies. The {sup 239}Pu and {sup 235}U enrichments of DUPIC fuel were adjusted by controlling the amount of fresh uranium feed and the ratio of slightly enriched and depleted uranium in the feed uranium. Based on the material balance calculation, it is recommended that DUPIC fuel composition be such that spent PWR fuel utilization is more than 90%. A sensitivity study on the temperature reactivity coefficient of DUPIC fuel and shown that it is desirable to increase the {sup 239}Pu and {sup 235}U contents to reduce both the fuel and coolant temperature coefficients. On the other hand, refueling simulations of the DUPIC core have shown that the ...

International Nuclear Information System (INIS)

Full text: The isotopic assay instrument under development at Pacific Northwest National Laboratory (PNNL) is capable of rapid prescreening to detect small and rare particles containing high concentrations of uranium in a heterogeneous sample. The isotopic measurement concept is based on laser vaporization of solid samples followed by sensitive isotope-specific detection using either uranium atomic fluorescence emission or uranium atomic absorbance. Both isotopes are measured concurrently, following a single ablation laser pulse using two external-cavity violet diode lasers. The simultaneous measurement of both isotopes enables the correlation of the fluorescence and absorbance signals on a shot-to-shot basis. This measurement approach demonstrated negligible channel crosstalk between isotopes. Scanning the heterogeneous samples provides high-resolution imagery of sample isotopic fluorescence and absorbance. Isotopically ...

International Nuclear Information System (INIS)

This paper discusses essentially the role of WDXRFS based multi element data in uranium exploration, with special reference to India. The state of art MagiX-PRO WDXRFS with 4 kW end window x-ray tubes has been used in the present study as an indispensable geo-analytical tool for the analysis of major and selected trace elements at ppm to percentage level, with high precision and relatively better accuracy

International Nuclear Information System (INIS)

The purpose of the Ocean FUSRAP Program, which began in March 1981, is to assess the technical, environmental, and institutional feasibility of disposing, in the ocean and on the ocean floor, of FUSRAP waste which contains traces of natural radioactive materials. The initial planning has focused on the Middlesex, New Jersey, Sampling Plant site and surrounding properties, which contain on the order of 100,000 metric tons of material. The Belgian Congo uranium ore and other uranium ores used by the United States were handled at the sampling plant site and have since been removed.

Energy Technology Data Exchange (ETDEWEB)

The fusion breeder is a fusion reactor designed with special blankets to maximize the transmutation by 14 MeV neutrons of uranium-238 to plutonium or thorium to uranium-233 for use as a fuel for fission reactors. Breeding fissile fuels has not been a goal of the US fusion energy program. This paper suggests it is time for a policy change to make the fusion breeder a goal of the US fusion program and the US nuclear energy program. The purpose of this paper is to suggest this policy change be made and tell why it should be made, and to outline specific research and development goals so that the fusion breeder will be developed in time to meet fissile fuel needs.

Energy Technology Data Exchange (ETDEWEB)

Five nomographs have been prepared that facilitate the estimation of cover thickness and cover material volume for the Uranium Mill Tailing Remedial Action Program. Key parameters determined include the cover thickness with either a surface radon flux or a boundary radon air concentration criterion and the total volume of cover material required for two different treatments of the edge slopes. Also included in the engineering guide are descriptions and representative values for the radon source term, the diffusion coefficients and the key meteorological parameters. 16 refs., 7 figs., 2 tabs.

International Nuclear Information System (INIS)

The Lake Charles and Port Arthur quadrangles cover approximately 10,950 square miles of land west of the Mississippi River delta area. The area overlies thick sections of the Gulf of Mexico Basin. Surficial exposures are dominated by Recent and Pleistocene sediment. A search of available literature revealed no known uranium deposits. A total of 82 uranium anomalies were detected and are discussed briefly in this report. None were considered significant and all appear to relate to cultural features. Magnetic data appear to be in agreement with existing structural interpretations of the area.

International Nuclear Information System (INIS)

This study was carried out mainly to produce uranium trioxide (UO_3), with the standard of commercial specifications from rock phosphate deposits in eastern part of Nuba mountains, south Kurdufan state. A simplified hydrometallurgical procedure has been adopted for production of yellow cake from the ore. Elemental analysis has shown that the ore is rich in Ca and deficient in elements of potential interest such as Fe, Cu and Zn. Uranium content in ore, phosphoric acid and purified yellow cake (UO_3) obtained with different precipitants was analyzed using alpha-spectrometry. On the average, the activity concentration of uranium in ore corresponds to 82 #+-# 24 ppm (0.10%). From the data of pregnant liquor, it was observed that the addition of KCIO_3 as an oxidant improves the dissolution of uranium from the ore by almost 20%. Data has also indicated that the yellow cake purified by hydrogen peroxide has ...

Energy Technology Data Exchange (ETDEWEB)

Accelerated aging tests on tin-oxide-coated anodized aluminium selective absorber surfaces have been performed. It is shown that the tin oxide layer provides excellent protection for the anodized surface. The thermal stability of the double layer is equal to, or better than, the stability of the bare anodized surface. Both surfaces degrade very slowly at 450deg C. The anodic layer is porous and therefore not very scratch resistant and it degrades when exposed to humidity, both acidic and alcaline. It is shown that the tin oxide film, which is hard and chemically very stable, almost completely protects the anodized surface from chemical degradation. The mechanical wear resistance is also considerably improved. The optical selectivity does not quite match that of the the anodized surface, but the remarkable stability together with the solar parameters of {alpha}=0.91 and hemispherical emittance {epsilon}= 0.16 (normal emittance {epsilon}{sub n}=0.12) make this ...

Energy Technology Data Exchange (ETDEWEB)

We tried to apply a quartz crystal as a sensor by using the resonant frequency and the resistance properties of quartz crystals. Four kinds of fatty acids that have the same head groups were coated on the surfaces of the quartz crystals, and the shift of the resonant frequency and the resistance were observed based on the lengths of the tail groups. Myristic acid (C{sub 14}), palmitic acid (C{sub 16}), stearic acid (C{sub 18}), and arachidic acid (C{sub 20}) were deposited on the surfaces of quartz crystals by using the Langmuir-Blodgett (LB) method. As a result, the resonant frequency change was more sensitive to high molecular-weight fatty acids than to low molecular-weight ones. We also observed the effect of temperature on stearic acid LB films, and the response properties of quartz crystals coated with stearic-acid LB films to organic gases were investigated. As a result, the sensitivity of quartz crystals to organic gases was higher for higher molecular-weight gas, and we found ...

International Nuclear Information System (INIS)

Spherical nanostructured Si/C composite was prepared by spray drying technique, followed by heat treatment, in which nanosized silicon and fine graphite particles were homogeneously embedded in carbon matrix pyrolyzed by phenol formaldehyde resin. Cyclic voltammetry tests showed two pairs of redox peaks corresponding to lithiation and delithiation of Si/C composite. The Si/C composite exhibited a reversible capacity of 635 mAh g"-"1 and good cycle performance used in lithium ion batteries. To improve cycle performance of this Si/C composite further, the carbon-coated Si/C composite was synthesized by the second spray drying and heat treatment processing. The cycle performance of carbon-coated Si/C composite was improved significantly, which was attributed to the formation of stable SEI passivation layers on the outer surface of carbon shell which protected the bared silicon from exposing to electrolyte directly.

International Nuclear Information System (INIS)

Data by Wiesmann et al. on the temperature coefficient of the upper critical field, dH/sub c/2(T)/dT, and the normal-state resistivity rho_0 near the superconducting transition temperature T/sub c/ are analyzed to estimate the bare density of states N (E/sub F/) as a function of structural disorder and T/sub c/ in various #alpha#-particle irradiated samples of A-15 Nb_3Ge and Nb_3Sn. By taking into account the change in the electron-phonon coupling strength with T/sub c/ and the effect of mass enhancement arising from the electron-phonon interaction, the results of the new analysis indicate that (i) the drop in N (E/sub F/) for Nb_3Ge is relatively small as T/sub c/ changes from approx. 21 to approx. 4 K, in agreement with a recent low-temperature specific-heat measurement; (ii) the value of N (E/sub F/) in Nb_3Sn decreases by a factor of approx. 4 as T/sub c/ varies from approx. 18 to approx. 3 K. The implication of these findings is discussed in terms of the ...

Energy Technology Data Exchange (ETDEWEB)

Infrainguinal peripheral occlusive disease is increasingly being treated by endovascular techniques. Bare metal stainless steel, self-expanding nitinol stents, drug-eluting and covered stents (stent grafts) are becoming increasingly more important adjuncts to percutaneous translumninal angioplasty in the treatment of peripheral artery disease. In this article the available evidence supporting the use of stents in the femoropopliteal and tibial arteries will be described as well as their limitations. Future stent developments will also be discussed. (orig.) [German] Die endovaskulaere Therapie spielt bei der Therapie der peripheren arteriellen Verschlusskrankheit (PAVK) eine wichtige Rolle. Unbeschichtete ballonexpandierbare Stahlstents, selbstexpandierende Nitinolstents sowie medikamentenbeschichtete und ''covered stents'' (Stentgrafts) haben eine zunehmende Bedeutung als Zusatztherapie zusammen mit der primaeren ...

International Nuclear Information System (INIS)

The hydrogen evolution reaction (HER) was studied on bare brass (B), nickel coated brass (B/Ni), nickel-zinc alloy coated brass (B/NiZn, leached Zn), nickel (under layer)/nickel-zinc alloy coated (top layer) brass electrodes (B/Ni/NiZn, leached Zn) in 1 M NaOH solution using electrolysis, cathodic polarization and electrochemical impedance spectroscopy (EIS) techniques. Long term tests were performed in order to evaluate the electrocatalytic activity and corrosion performance of the prepared electrodes with operation time. The results showed that leached electrodes, especially B/Ni/NiZn electrode, have a smaller overpotential than the others and a good electrocatalytic activity for the HER. Its electrocatalytic activity is also stable over electrolysis time. Contrary to the HER performance, B/NiZn cannot provide an adequate corrosion protection. However, when a thin Ni layer was coated under the NiZn alloy coating (B/Ni/NiZn), a greater electrocatalytic stability ...

Energy Technology Data Exchange (ETDEWEB)

The origin of natural gas in the Japanese oil and gas fields are geochemically studied. Samples are taken from structural natural gas, surface gas seepage, water-dissolved natural gas and coal-field gas of the Japan Sea coast area. The origins of primary hydrocarbons are classified into bacteria gas and thermogenic gas, the latter being subclassified into gas in oil production zone with the per million deviation of the carbon isotope (/sup 13/C/sup 1/) of methane less than -35 and those gases with maturity higher than this. Surface gas seepage is subjected to migration and bacterial oxidation. Coal gas is similar to oil gas. The CO/sub 2/ concentration is 0 - 2% and /sup 13/CO/sub 2/ deviations from -30 - +30. The origin can be barely estimated from the isotopic composition because of the wide secondary change in the composition. The origin and migration of gas from the gas field of northern Niigata are not similar to those in the southern area, which consist of a ...

Energy Technology Data Exchange (ETDEWEB)

The purpose of this text is to train engineers and technologists not just to understand corrosion but to control it. Materials selection, coatings, chemical inhibitors, cathodic and anodic protection, and equipment design are covered in separate chapters. High-temperature oxidation is discussed in the final two chapters ne on oxidation theory and one on controlling oxidation by alloying and with coatings. This book treats corrosion and high-temperature oxidation separately. Corrosion is divided into three groups: (1) chemical dissolution including uniform attack, (2) electrochemical corrosion from either metallurgical or environmental cells, and (3) stress-assisted corrosion. Corrosion is logically grouped according to mechanisms rather than arbitrarily separated into different types of corrosion as if they were unrelated. For those university students and industry personnel who approach corrosion theory very hesitantly, this text will present the electrochemical reactions responsible ...

Energy Technology Data Exchange (ETDEWEB)

Electrochemical noise generated during stress corrosion cracking (SCC) of type 304 stainless steel (UNS S30400) and {alpha}-brass were studied. Noise patterns showed common characteristics (i.e., a quick drop and slow recovery of the potential). The quick drop corresponded to the initiation of localized events where fresh metal was exposed. The slow recovery corresponded to the repassivation process of the exposed bare metal. The potential drop rate and recovery rate were almost constant during the SCC process for a given SCC system. For random noise, rates of potential rise and drop were similar. Frequency of the noise generated during SCC increased with an increase in applied stress. SCC initiation could be monitored and determined according to noise characteristics and distribution. Since the shift of background potentials had an obvious influence on characteristics of power spectrum density (PSD), the direct current (DC) component should be removed before ...

Energy Technology Data Exchange (ETDEWEB)

TNF-doped Mylar is a new radiation-hard dielectric that has recently been qualified as a viable substitute for Mylar in capacitors. The advantage of TNF-doped Mylar is that it satisfies both the nuclear safety and radiation hardness requirements of weapons. Mylar is not radiation-hard. Aging and compatibility studies were carried out to insure that (1) TNF does not diffuse from the film during fabrication of the capacitor or during storage; and (2) there are no compatibility problems with aluminum foil (the conductor) or Fluorinert (the secondary dielectric). Losses of TNF were barely detectable during the vacuum bakes used in fabricating capacitors or during accelerated aging tests carried out below T{sub g} (70C) over a two year period in air. In other accelerated tests, no compatibility problems were detected with aluminum or Fluorinert. TNF-doped Mylar is now being used in the MC-4109 capacitor that was called out for use in SRAM II. We anticipate no ...

Science.gov (United States)

Environmental monitoring data were collected at and around the Area 3 and Area 5 Radioactive Waste Management Sites (RWMSs) at the Nevada Test Site. These data are associated with radiation exposure, air, groundwater, meteorology, vadose zone, subsidence, and biota. This report summarizes the 2006 environmental data to provide an overall evaluation of RWMS performance and to support environmental compliance and performance assessment (PA) activities. Some of these data (e.g., radiation exposure, air, and groundwater) are presented in other reports (U.S. Department of Energy, 2006; Warren and Grossman, 2007; National Security Technologies, LLC, 2007). Direct radiation monitoring data indicate that exposure levels around the RWMSs are at or below background levels. Air monitoring data at the Area 3 and Area 5 RWMSs indicate that tritium concentrations are slightly above background levels. There is no detectable man-made radioactivity by gamma spectroscopy, and concentrations of americium ...

International Nuclear Information System (INIS)

In the case where uranium recovered by an advanced aqueous reprocessing is utilized in light water reactors (LWRs) with the thermal neutron spectrum, the effects of the decontamination factor (DF) of the reprocessing on core neutronic characteristics were examined. The amounts of transuranium (TRU) elements and fission products (FPs) contained in the recovered uranium depend on the DF of reprocessing, and also "2"3"6U is generated by neutron capture of "2"3"5U during a reactor operation. These all act as poisons in the fuel. Therefore, in this paper, the additional "2"3"5U enrichment necessary to compensate for the produced TRU elements, FPs, and "2"3"6U was evaluated for three representative DF values: 10"2, 10"3, and infinity. The low value of 10"2 corresponds to the advanced aqueous reprocessing investigated here. An APWR core with a discharge burnup of 49 GWd/t when the initial "2"3"5U enrichment is 4.6% was considered as the reference ...

International Nuclear Information System (INIS)

The environmental impacts of uranium mining and milling activities are of great concern in many countries for the last three decades. These impacts range from the creation of massive stockpiles of radioactive and toxic waste rock and sand-like tailings to serious contamination of surface and groundwater with radioactive and toxic pollutants, and releases of conventional, toxic and radioactive air pollutants. Uranium mining is also associated with high concentrations of highly toxic heavy metals, which are a major source of surface and groundwater contamination. Depending upon the hydraulic properties of the fractures involved, contaminated ground water may be transported many miles from its point of origin before feeding into an aquifer. Tailings pond may contaminate the groundwater regime by continuous seepage and leaching of radionuclides and other toxic metals due to interaction of rain water through the tailings ponds. The ...

International Nuclear Information System (INIS)

The principal types of uranium deposits in Ontario are carbonatites and fenites, alkalic volcanic rocks, pegiatites, calc-silicate rocks, pyritic quartz-pebble conglomerates, polymictic conglomerates and some pelitic rocks, and various 'pitchblende' deposits including late Precambrian unconformities, possibly late Precambrian diabase dikes, and other unconformities: carbonates, sandstones, lignites, and semi-pelitic rocks of middle and upper Precambrian age. Only red unzoned pegmatite and the pyritic quartz-pebble conglomerate have supported production. Ontario reasonably assured and estimated resources in the economic and subeconomic categories in 1977 amounted to 553 000 tonnes U, and 1977 production was 4000 tonnes U. Measured, indicated, and inferred resources in the Elliot Lake - Agnew Lake area are at least 400 000 tonnes U. The latter deposits are also a significant thorium resource. Geological features reflecting major changes in physics and chemistry are ...

International Nuclear Information System (INIS)

TRACI, a model based on the physical mechanisms governing the radon transport in unsaturated soils, has been developed to evaluate the radon flux density at Uranium Mill Tailings (UMT) covers surface. First, moisture contents in the soil, induced by weather conditions, are calculated. Then, radon concentrations in the air-filled pore space, and radon flux density at the soil surface, are deduced from a transport model which takes account for diffusion and convection in the pore space. To check the hypothesis used in TRACI and the efficiency of cover layers, an in situ study was launched in 1997 with the French uranium mining company, COGEMA. It consists of continuous measurements of moisture contents, suctions, radon concentrations at various depths inside an UMT cover, and flux density at its surface. The first analysis made on in situ observations shows that radon concentrations and flux density, calculated with a steady-state diffusion model ...

Energy Technology Data Exchange (ETDEWEB)

Rehabilitation of the abandoned uranium mining areas in Saxonia and Thuringia is a task posing also legal problems. The radiation protection laws of the former GDR continued to be effective to a great extent and proved to be a legal basis not ``perfect`` in formal terms, but suitably efficient in practice to tackle the manifold problems encountered in the land reclamation and waste disposal work. Originally intended to serve as a legal interim regime awaiting amendment at a later date, the body of laws available for the task proved to be a sufficient basis. (orig./HP) [Deutsch] Das fortgeltende Strahlenschutzrecht der frueheren DDR hat sich zwar nicht als formal `perfektes`, in der Sache aber strahlenschutzgerechtes und praktikables Instrument zur Loesung der anstehenden Sanierungsaufgaben erwiesen. Bei seiner Beurteilung darf nicht ausser Acht gelassen werden, dass die Ueberleitung dieses Rechts seinerzeit aus der Not eines kurzfristigen Regelungsbedearfs geboren ...

International Nuclear Information System (INIS)

In order to effectively recover uranium, rotation speed of solid cathode was examined, and effect of uranium concentration and current density on electrodeposition were confirmed. And the potentiostatic and galvanostatic electrorefining experiments were conducted. Element used in the experiments were Zr, Nd, La chlorides. The reduction potentials of chlorides metals on liquid Cd cathode were measured by cyclic voltammetry experiments. The electrowinning experiments were performed in order to recover small amounts of uranium in salt. Experimental set-up for the batch type reductive extraction experiments were developed and installed. On the base of experimental results of batch type, multi-stage extraction equipment was set-up, and optimum number of stage and recover yield were measured. In the oxidative extraction study is examine selective separation behavior of the rare earth metals from alloy composed of actinide and ...

Energy Technology Data Exchange (ETDEWEB)

To carry out studies on the radon behavior under controlled and stable conditions it was designed and constructed a system that consists of two parts: a container of mineral rich in Uranium and an experimentation chamber with radon united one to the other one by a step valve. The container of uranium mineral approximately contains 800 gr of uranium with a law of 0.28%; the radon gas emanated by the mineral is contained tightly by the container. When the valve opens up the radon gas it spreads to the radon experimental chamber; this contains 3 accesses that allow to install different types of detectors. The versatility of the system is exemplified with two experiments: 1. With the radon experimental chamber and an associated spectroscopic system, the radon and two of its decay products are identified. 2. The design of the system allows to couple the mineral container to other experimental geometries to demonstrate this fact ...

International Nuclear Information System (INIS)

Applying the theory of depositional system, the depositional facies and depositional systems of the Zhiluo Formation in Dongsheng area are systematically analysed, and the authors proposed that sediments of the Zhiluo Formation are of fluvial facies, and streams of the Zhiluo time experienced three evolution stages, namely: the early braided stream, the middle low sinuosity meandering stream and the late high sinuosity meandering stream. Based on features of paleoclimatic evolution, the Zhiluo Formation is divided into two lithological members. The lower lithological member consists of sediments of braided and low sinuosity meandering streams under humid-ward paleoclimatic conditions forming grey sedimentary formation. The upper member is composed of sediments of meandering streams under arid-hot paleoclimatic conditions representing complex-colored (mainly red) sedimentary formation. It is suggested that uranium mineralization in the study area is of channel ...

Energy Technology Data Exchange (ETDEWEB)

One option in establishing advanced technology for disposing of high-level radioactive waste (HLW) is to remove TRU elements from HLW and then transform them into short-lived radionuclides. Tertiary pyridine-type anion exchange resin was investigated as a separation medium for spent fuel reprocessing using a HCl solution. Distribution coefficients of typical elements, along with uranium, were measured in the pyridine resin--HCl solution system, where HCl concentration was varied from 1 to 9 M. The results reveal: elements of the alkali metal, alkaline earth and lanthanide groups are not adsorbed, the adsorption patterns of the transition metals differ according to HCl concentration, and uranium is adsorbed in the high HCl concentration region. Furthermore, the present report describes the experimental results obtained for the adsorption behaviour of uranium, americium, curium and various lanthanide elements on tertiary ...

International Nuclear Information System (INIS)

A biogenic method for the treatment of uranium mill effluents containing toxic amounts of Mn"2 and "2"2"6Ra is described. The acidic tailings from the uranium mills are generally neutralised with lime and the overflow waters from tailing ponds at the discharge point, consisting of Mn"2"+ (>10 mg l"-"1) and "2"2"6Ra (> 3.0 pCi l"-"1), need further treatment before disposing off to the public utility. Arthrobacter sp. has been used for precipitating Mn"2"+ as hydrous oxide of manganes (MnO_2#centre dot#nH_2O) and along with "2"2"6Ra also gets precipitated. The effluent after bacterial treatment consisted of Mn"2"+ and "2"2"6Ra within the range of allowed concentrations as per the I.C.R.P. (International Committee of Radiological Protection) and MPC (maximum permissible concentration) standards (Mn"2"+ 95% of "2"2"6Ra could be precipitated using this method. (author). 11 refs.; 4 figs.; 4 tabs.

Energy Technology Data Exchange (ETDEWEB)

In the framework of the search for a ceramic material usable in the radioactive waste storage, uranium and thorium phosphates have been investigated. Their experimental synthesis conditions have been entirely reviewed, they lead to the preparation of four new compounds: U(UO{sub 2})(PO{sub 4}){sub 2}, U{sub 2}O(PO{sub 4}){sub 2}, UCIPO{sub 4}, 4H{sub 2}O, and Th{sub 4}(PO{sub 4}){sub 4}P{sub 2}O{sub 7}. Experimental evidenced are advanced for non existent compounds such as: U{sub 3}(PO{sub 4}){sub 4}, U{sub 2}O{sub 3}P{sub 2}O{sub 7} and Th{sub 3} (PO{sub 4}){sub 4}. Characterization by several techniques (X-rays and neutron powder diffractions, UV-Visible and Infra-red spectroscopies, XPS,...) were performed. The ab initio structure determination of U(UO{sub 2})(PO{sub 4}){sub 2} has been achieved by X-rays and refined by neutron diffractions. Through its physico-chemical analysis, we found that this compound was a new mixed valence uranium ...

Energy Technology Data Exchange (ETDEWEB)

Polymeric coated ferromagnetic carriers with an absorbed layer of octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) diluted by tributyl phosphate (TBP) are being evaluated for application in the separation and the recovery of low concentrations of americium, plutonium, and uranium from nuclear waste solutions. Due to their chemical nature, these extractants selectively complex americium and plutonium contaminants onto the particles and the complexed particles can be recovered from the solution using a magnet. Physical and chemical characterization of the extractant-absorbed particles were performed by gamma and liquid scintillation counting, scanning electron microscopic (SEM) micrograph, and other physical measurements. Plutonium, americium, and uranium separations have been performed at various HNO{sub 3} and HCl concentrations. Parameters were studied to determine the limitations and capacity of the process. The status of the ...

Energy Technology Data Exchange (ETDEWEB)

Ford, Bacon, Davis Utah Inc. has reevaluated the Spook site in order to revise the December 1977 engineering assessment of the problems resulting from the existence of radioactive uranium mill tailings 48 mi northeast of Casper, in Converse County, Wyoming. This engineering assessment has included the preparation of topographic maps, the performance of core drillings and radiometric measurements sufficient to determine areas and volumes of tailings and radiation exposures of individuals and nearby populations, the investigations of site hydrology and meteorology, and the evaluation and costing of alternative corrective actions. Radon gas released from the 187,000 tons of tailings at the Spook site constitutes the most significant environmental impact, although windblown tailings and external gamma radiation also are factors.

International Nuclear Information System (INIS)

A new reagent 7-(6-Br-2-henzthiazolilazo)-8-oxyquinoline-5-sulphoacid has been studied spectrophotometrically. Dissociation constants have been determined in 50% acetone (pK_1=2.5 and pK_2=5.9) and 50% dioxane (pK_1=1.7 and pK_2=6.1) as well as molar extinction coefficients of the reagent dissociated form in the same solvents (71.1.10"3 and 72.4.10"3). The conditions have been studied of complexing the reagent with ions of uranium (6), zinc (2), and manganese (2) in 50% dioxane (pH 2.5-4.5) and the properties of the formed complexes.

Energy Technology Data Exchange (ETDEWEB)

A procedure was developed for separating rubidium from irradiated aluminum encapsulated uranium. The separations procedure produces a final ultra-high purity RbCl product for subsequent high performance mass spectrometric analysis. The procedure involves first removing most of the macro-components and fission products by strong base anion exchange using, first, concentrated HCl, then oxalic acid media and second, selectively separating rubidium from alkaline-earth ions and other alkali-metal ions, including cesium, using Bio-Rex-40 cation-exchange resin. The resultant RbCl is then put through a final vacuum sublimation step. Ultra-pure reagents and specially clean glassware are used throughout the procedure to minimize contamination by naturally-occurring rubidium.

British Library Electronic Table of Contents (United Kingdom)

Feasibility of using fixed bed column of conventional ion exchangers/sorbent and chemical precipitation based processes have been examined for the effective removal of the very low levels of 106Ru activity from NH4NO3 effluent generated during wet processing of rejected sintered depleted uranium fuel pellets. Based on the results, a simple process involving precipitation of cobalt sulphide along with ferric hydroxide was selected and further optimization of process variables was carried out. The optimized process has been found to be highly efficient in reducing 106Ru activity down to extremely low levels.

Energy Technology Data Exchange (ETDEWEB)

Three different fuels UO{sub 2}-only, UO{sub 2}-Gd{sub 2}O{sub 3}(5%), and UO{sub 2}-Gd{sub 2}O{sub 3}(10%) were produced by sol-gel technique. Their powder characteristics such as flowability, BET surface area, average pore diameter, and cumulative pore volume were determined. The pore size distributions of powders, green pellets, and sintered fuels were determined by using a mercury porosimeter. The theoretical densities of sintered fuels were found to be 98.01, 95.3, and 95.9 %, respectively. Their ruggedness fractal dimensions were 1.111, 1.044, and 1.042, while the fractal dimensions associated with the size distribution of grains were 1.44, 1.58, and 1.60, respectively. (orig.).

International Nuclear Information System (INIS)

We present a unified description of the imaginary part of the dynamical magnetic susceptibility #chi#"'"'(#omega#.T) and measurements of the static susceptibility #chi#(T) and electrical resistivity #rho#(T) in the uranium intermetallics UCu_5_-_xPd_x (x = 1.1.5). For temperatures T and excitation energies #omega# in the range 12 K < #omega#, T < 150 K, our analysis demonstrates that the dynamics of isolated uranium ions are responsible for the observed temperature and frequency scaling, although interion interactions may become important at lower temperatures and frequencies. We derive a strict criterion for single-ion scaling in the form of a universal scaling function, providing a model-independent description of the compiled experimental data. (orig.).

Energy Technology Data Exchange (ETDEWEB)

This report presents the results of an experimental programme to determine the mass transfer and sorptive properties of selected glacial sand and clays from the Drigg Disposal Site operated by British Nuclear Fuels plc. The hydraulic conductivity of both the sand and clay has been determined and the sensitivity of this parameter to changing water chemistry investigated. The hydrodynamic dispersion properties of the glacial sand were measured in order to aid the interpretation of column sorption experiments. The sorption of strontium and uranium from groundwater onto clay and sand samples has been studied using through-diffusion, column and batch techniques. Employing the batch technique, the effect of a series of humic acid concentrations on distribution ratios for uranium and plutonium has also been investigated. Groundwater and trench leachate were used with both clay and sand. (author).

CERN Document Server

The hyperfine interactions at the uranium site in the antiferromagnetic USb2 compound were calculated within the density functional theory (DFT) employing the augmented plane wave plus local orbital (APW+lo) method. We investigated the dependence of the nuclear quadruple interactions to the magnetic structure in USb2 compound. The investigation were performed applying the so called band correlated LDA+U theory self consistently. The self consistent LDA+U calculations were gradually added to the performed generalized gradient approximation (GGA) including scalar relativistic spin orbit interactions in a second variation scheme. The result, which is in agreement with experiment, shows that the 5f-electrons have the tendency to be hybridized with the conduction electrons in the ferromagnetic uranium planes.

International Nuclear Information System (INIS)

Being based on the Segal method, calculation was carried out for the natural uranium nuclear fuel cost with Zircaloy-4 cladding having design parameters of Wolsung Nuclear Power Plant, CANDU-PHWR (Unit 1), currently under construction in Korea aiming at its completion in 1982. An attempt was also made for the sensitivity analysis of each fuel component; i.e., depreciation of fuel manufacturing plant caused by its life time, its load factor, production scale expansion of plant facilities, variations of construction and operating costs of fuel manufacturing plant, fluctuation of interest rates, extent of uranium ore price increases and effect of learning factor. (author).

Energy Technology Data Exchange (ETDEWEB)

The US NRC, in its Generic Environmental Impact Statement on uranium milling has specified that the radon flux escaping a uranium mill tailings pile will be reduced to pCi/m/sup 2/ s by application of covering layers of soils and clays. These covers present a radon diffusion barrier, which sufficiently increases the time required for radon passage from the tailings to the atmosphere to allow for decay of /sup 222/Rn within the cover. The depth of cover necessary to reduce the escaping radon flux to the prescribed level is to be determined by calculation, and requires precise knowledge of the radon diffusion coefficient in the covering media. A Radon Attenuation Test Facility was developed to determine rates of radon diffusion through candidate cover materials. This paper describes this facility and its application for determining the influence of physical properties of the soil column on the radon diffusion coefficient.

International Nuclear Information System (INIS)

A Process for yellow cake production from local Euxenite was developed in Bench Scale by using sulphuric acid digestion with simultaneously ion-exchange and solvent extraction purification steps. Uranium was then precipitated as uranium diuranate by ammonia solution. Equipment used in this process includes : digestion vessels, columnar ion-exchange, solvent extraction and precipitation units Ore feed to the process could be adjusted up to 2 kilogram per day (8 hours operation) with yellow cake product purity meet the requirement of Usaec standard of about 10-50 gram per day. Included in this experiment are the leaching characteristics of the ore, the design and construction of continuous columnar 4-cycle ion exchange unit, determination of the extraction and stripping stages of a gravity flow mixer-settler and the design and construction of continuous yellow cake precipitation unit with large grain size and high density product

International Nuclear Information System (INIS)

The paper describes novel analytical methods developed for the detection of previous neutron irradiation and reprocessing of illicit nuclear materials, which is an important characteristic of nuclear materials of unknown origin in nuclear forensics. Alpha spectrometry and inductively coupled plasma sector-field mass spectrometry (ICP-SFMS) using solution nebulization and direct, quasi-non-destructive laser ablation as sample introduction were applied for the measurement of trace-level "2"3"2U, "2"3"6U and plutonium isotopes deriving from previous neutron irradiation of uranium-containing nuclear materials. The measured radionuclides and isotope ratios give important information on the raw material used for fuel production and enable confirm the supposed provenance of illicit nuclear material.

Energy Technology Data Exchange (ETDEWEB)

Biosorption of uranium (VI) ions by immobilized Aspergillus fumigatus beads was investigated in a batch system. The influences of solution pH, biosorbent dose, U (VI) concentration, and contact time on U (VI) biosorption were studied. The results indicated that the adsorption capacity was strongly affected by the solution pH, the biosorbent dose and initial U (VI) concentration. Optimum biosorption was observed at pH 5.0, biosrobent dose (w/v) 2.5%, initial U (VI) concentration 60 mg L{sup -1}. Biosorption equilibrium was established in 120 min. The adsorption process conformed to the Freunlich and Temkin isothermal adsorption models. The dynamic adsorption model conformed to pseudo-second order model.

Energy Technology Data Exchange (ETDEWEB)

This report presents the results of a study dealing with the homogeneous recycling of either Pu or Pu+Np or Pu+Np+Am or Pu+Np+Am+Cm in PWRs using MOX-UE fuel, i.e. standard MOX fuel with a U235 enriched uranium support instead of the standard tail uranium (0.25%) for standard MOX fuel. This approach allows to multirecycle Pu or TRU (Pu+MA) as long as U235 is available, by keeping the Pu or TRU content in the fuel constant and at a value ensuring a negative moderator void coefficient (i.e. the loss of the coolant brings imperatively the reactor to a subcritical state). Once this value is determined, the U235 enrichment of the MOX-UE fuel is adjusted in order to reach the target burnup (51 GWd/t in this study).

Energy Technology Data Exchange (ETDEWEB)

Volume one contains calculations for: embankment design--embankment material properties; Union Carbide site--bedrock contours; vicinity properties--origin of contamination; North Continent and Union Carbide sites contaminated materials--excavation quantities; and demolition debris--quantity estimate.

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The transverse flow of cohesive powders of uranium in a rotating kiln equipped with raising levers has been studied experimentally at ambient temperature and at the temperatures of the process. The simple laws obtained have permitted to calculate the average distribution of the powder in a straight section of the kiln. (J.S.)

International Nuclear Information System (INIS)

The article deals with the effects of various hazardous materials in the working environment. Some of these may be detrimental to the safety and health of the worker. The absorption of hazardous substances by the human body is discussed, as well as the effects of toxic substances. The hazardous substances are classified into the following categories: irritants, asphyxiants, anaesthetics and narcotics, carcinogens, mutagens, teratogens, systemic poisons, hazardous particulate matter and the biotransformation of toxic substances. Examples of hazardous substances include: industrial solvents, fumes and vapours, lead, mercury and uranium.

International Nuclear Information System (INIS)

As a new production technique of yellow cake, resorption with loaded resin-elution with acid ammonium nitrate-precipitation in two steps is studied. The results show that the produced yellow cake by the new production technique has better performance of settlement, filtration and dehydration. Each index of yellow cake accords with the first grade level issued by CNNC without washing, uranium and water content are 70% and 25%, respectively

International Nuclear Information System (INIS)

According to the data of drill cores, outcrops and well logging, two orders base-level cycles are recognized from Zhiluo Formation in Dongsheng area, which consist of 8-14 short-term base-level cycles and 3 mid-term base-level cycles, and their structural types and stacking patterns are discussed by using principles and methods of high-resolution sequence stratigraphic theory. Based on the correlation of mid-term base-level cycles, the control of the A/S (Accommodation/Sediment supply) ratio in mid-term base-level cycles on the scale of sand bodies and physical properties of reservoir is analysed. Studies show that the sand bodies of braided stream in MSC1 of Zhiluo Formation are favourable to uranium mineralization, however, the sand bodies of meandering river in MSC2 and MSC3 are not favourable to uranium mineralization. The change of the A/S results in the difference in characters of sand body, such as physical properties, continuity and so ...

International Nuclear Information System (INIS)

This rebuttal to a previous article provides new insight into the use of sprayed sealants in uranium mines. The author rejects the idea that the value of rock sealant on radon control is destroyed by changes in barometric pressure, showing that this is not necessarily true. The analyses described demonstrate that radon contamination resulting from changing barometric pressures is reduced by a rock coating. The overall use of coatings depends on their costs and effectiveness as compared with other radon control measures. 6 refs.

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This volume contains appendices D6 through D8 containing laboratory test data: from MK-F investigation, 1987, Old Rifle and New Rifle sites; on bentonite amended radon barrier material; and from MK-F investigation, 1987, riprap tests.

International Nuclear Information System (INIS)

Brief summaries are given of research carried out in the following areas: absorption spectroscopy of titanium, niobium, and molybdenum in uranium alloys; atomic absorption spectroscopy of selenium in stainless steel, computer program improvements for spectrophotometer control, and detection of beryllium in stack gases; electrolysis for inactivation of bacteria in cooling-tower water; improved solvent analysis by gas chromatography; sequential radionuclide separation for various sample matrices; progress on an electron microprobe analyzer; and miscellaneous projects.

International Nuclear Information System (INIS)

A variety of critical experiments were constructed of enriched uranium metal during the 1960s and 1970s at the Oak Ridge Critical Experiments Facility (ORCEF) in support of criticality safety operations at the Y-12 Plant. The purposes of these experiments included the evaluation of storage, casting, and handling limits for the Y-12 Plant and providing data for verification of calculation methods and cross-sections for nuclear criticality safety applications. These included solid cylinders of various diameters, annuli of various inner and outer diameters, two and three interacting cylinders of various diameters, and graphite and polyethylene reflected cylinders and annuli. Of the hundreds of delayed critical experiments, one experiment was comprised of a stack of approximately 7-inch-diameter metal discs. The bottom of the stack consisted of uranium with an approximate height of 4-1/8 inches. The top of the stack consisted of beryllium with an ...

Science.gov (United States)

Nuclear magnetic resonance results are presented for a number of NaCl-type compounds and cubic Laves-phase type compounds of uranium, neptunium, and plutonium. Special emphasis is placed on the Knight shift and spin-lattice relaxation time measurements and their interpretation in terms of localized or itinerant pictures of the 5Line integral electrons.

International Nuclear Information System (INIS)

Processing certain raw materials containing natural radioactive isotopes (e.g. U-238, Th-232 or K- 40) into products such as glas, abrasives, grinding materials or electrodes used for gasshielded tungsten-arc welding also leads to certain concentrations of industrial waste containing natural radioactive materials. Such industrial waste does not necessarily contain natural radioactive substances in concentrations exceeding the highest possible levels but nevertheless in significantly measurable quantities. This, however, frequently leads to confusion bordering on irritation by entities processing such substances as well as the general public, since they tend to believe natural radioactive substances in unobjectable concentration to cause similar or identical - health - consequences as man made radioactive substances in detrimental concentration. Radioactive materials may be incorporated intentionally or unintentionally into the product as main or additional ingredients. The recent ...

Energy Technology Data Exchange (ETDEWEB)

This investigation involves a study of the influence of key processing parameters on the heating of materials using microwave energy. Selective and localized heating characteristics of microwaves will be utilized in the sintering of ceramics without hydrostatic pressure. In addition, combustion synthesis will be studied for the production of powders, carbides, and nitrides by combining two or more solids or a solid and a gas to form new materials. The insight gained from the interaction of microwaves with various materials will be utilized in the mobilization and subsequent redeposition of uranium.

International Nuclear Information System (INIS)

The compound UC_2Si_2 has been found to be ferromagnetic at low temperatures with a Curie temperature of 101"0K. The magnetization follows a Curie-Weiss law in the paramagnetic region with an effective magneton number of 2.12 Bohr magnetons per uranium atom. Partial substitution of Th atoms for the U atoms results in an expansion of the lattice, a rapid drop in the Curie temperature, and a sizable increase in the coercive field.

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This ISB, in conjunction with the IOSR, provides the required basis for interim operation or restrictions on interim operations and administrative controls for the facility until a SAR is prepared in accordance with the new requirements or the facility is shut down. It is concluded that the risks associated with tha current and anticipated mode of the facility, uranium disposition, clean up, and transition activities required for permanent closure, are within risk guidelines.

CERN Document Server

The hyperfine interactions at the uranium site in the antiferromagnetic USb2 compound were calculated within the density functional theory (DFT) employing augmented plane wave plus local orbital (APW+lo) method. We investigated the dependence of the nuclear quadruple interaction to the magnetic structure in USb2 compound. The result shows that the 5f-electrons have the tendency to be hybridized with the conduction electrons.

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Biosorption means the storage of substances at the cell envelope. Different microbial biomasses were tested for the separation of radionuclides from mining waters. Results of a pilot plant demonstrate the ability of these techniques for water cleaning processes. An effluent concentration of lower than 1 mg/l (in most cases 0.1 mg/1) could be realized in a pilot plant by using pure cells of a methylotrophic strain of bacteria as well as using of a fungal mycelia.

Energy Technology Data Exchange (ETDEWEB)

The MEX-15 is a conceptual design of a Multipurpose Reactor with thermal power of 15 MW and this reactor is pool type with fuel plates U{sub 3}0{sub 8}-Al of low enrichment uranium. This report presents the static calculation for the MEX-15 reactor using SRAC code system and was developed under the collaboration agreement between ININ-JAERI in Research Reactor Technology Development Division of Department of Research Reactor in Tokai Research Establishment. (Author)

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The permeation of hydrogen through steam generator tubes at high temperatures ({approx} 300 degrees C) has been studied using an electrochemical technique. With this technique, hydrogen is generated on one side of the tube and monitored on the other side. The time for the hydrogen to reach the other side is used to determine the diffusion coefficient of hydrogen in the tube. Boundary conditions at the entry and exit sides have been investigated separately. Preliminary studies were performed on Stainless Steel 316 and Nickel Alloy 800 to better understand the influence of the solution chemistry on the electrochemical evolution of hydrogen. The surface phenomena effect and the trapping effect are discussed to account for differences observed in the permeation response. The hydrogen permeation through oxides at the exit side has been studied. Two nickel alloys (Alloy 800 and Alloy 600), materials widely used for steam generator tubes, have been investigated. The tubes were prefilmed using ...

Science.gov (United States)

The photopumped phonon-assisted laser operation (612 nm, 77 K) of a high-gapIn/sub 1/minus//ital y//(Al/sub /ital x//Ga/sub 1/minus//ital x//)/sub /ital y//P quantum wellheterostructure (QWH) lattice matched to GaAs (/ital y/approx.0.5) is identified usinga single rectangular sample that is shifted in its heat sinking from (a) low/ital Q/ when clamped onto Au (bare edges) to (b) high /ital Q/ when furthercompressed into Au with all four edges reflecting. For the low-/ital Q/ QWH samplephotopumped in a spot (partially photopumped), phonon-assisted laser operation(abrupt threshold, narrow spectrum) is observed on closely spaced end-to-endlaser modes ..delta../ital E/=/h bar/..omega../sub LO/approx.45--47 meV below the lowestconfined-particle transitions. For the /ital same/ sample shifted tohigh /ital Q/, edge-to-edge laser operation across the sample on confined-particletransitions is ''turned on'' also, thus providing an ...

International Nuclear Information System (INIS)

On the basis of soil losses records during 10 years, three levels of water erosion were established for two soil (Typical Hapludox and Oxic Dystropept) located on high and medium terraces of alluvial flat plain of piedmont in the Eastern Plains in La Libertad Research Center of CORPOICA. Eighteen 3 x 10 m"2 run-off plots were fitted out on a nonrandom arrangement of nine plots by landscape and three soil use and management treatments: zero grazing Brachiaria decumbens pasture for six years, up land rice, soybean and maize rotations for six years and bare soil for 10 years. Soil losses under these treatments allowed to define three degrees of erosion: slight (N_3 moderate (N_2) and severe (N_3) respectively. From each plot soil samples were taken at two depths for physical analyses. infiltration and resistance to cone penetration were measured in the field. Without exception water erosion produced a detrimental effect on soil physical properties and the hydrological ...

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Alloy 600 is commonly used in the primary systems of PWR plants because of its excellent resistance to a stress corrosion cracking and pitting. But a stress corrosion cracking and pitting corrosion are occasionally observed under PWR conditions, which may be correlated with the passive film on the Alloy 600 surface. There is little information on the composition of films growing on the surface of Alloy 600 at high temperature. Therefore, an understanding of the basic electrochemical behaviors about an anodic dissolution and the passivation of the bare surface of metals and alloys provides important information about localized corrosions like a SCC and pitting. Oxide on the steel surfaces in an aqueous solution above 100 .deg. C is composed of a duplex film structure. The inner layer of the oxide is dense and less porous, which is formed by a growth of the oxide layer on the metal surface. Outer layer of the oxide is less adhesive, which is formed by a dissolution ...

Energy Technology Data Exchange (ETDEWEB)

Chromium nitride/Cr coating has been deposited on surface of 316L stainless steel to improve conductivity and corrosion resistance by physical vapor deposition (PVD) technology. Electrochemical behaviors of the chromium nitride/Cr coated 316L stainless steel are investigated in 0.05 M H{sub 2}SO{sub 4}+2 ppm F{sup -} simulating proton exchange membrane fuel cell (PEMFC) environments, and interfacial contact resistance (ICR) are measured before and after potentiostatic polarization at anodic and cathodic operation potentials for PEMFC. The chromium nitride/Cr coated 316L stainless steel exhibits improved corrosion resistance and better stability of passive film either in the simulated anodic or cathodic environment. In comparison to 316L stainless steel with air-formed oxide film, the ICR between the chromium nitride/Cr coated 316L stainless steel and carbon paper is about 30 m{omega} cm{sup 2} that is about one-third of bare 316L stainless steel at the compaction ...

Energy Technology Data Exchange (ETDEWEB)

This study was undertaken during 1991 - 1998 to identify the origin of plutonium uranium in northern New Mexico Rio Grande and tributary stream sediments. Isotopic fingerprinting techniques help distinguish radioactivity from Los Alamos National Laboratory (LANL) and from global fallout or natural sources. The geographic area covered by the study extended from the headwaters of the Rio Grande in southern Colorado to Elephant Butte Reservoir in southern New Mexico. Over 100 samples of stream channel and reservoir bottom sediments were analyzed for the atom ratios of plutonium and uranium isotopes using thermal ionization mass spectrometry (TIMS). Comparison of these ratios against those for fallout or natural sources allowed for quantification of the Laboratory impact. Of the seven major drainages crossing LANL, movement of LANL plutonium into the Rio Grande can only be traced via Los Alamos Canyon. The majority of sampled locations within and ...

International Nuclear Information System (INIS)

Critical experiments have been analyzed to verify a nuclear analysis system for fast reactors used in Japan Nuclear Cycle Development Institute (JNC). The experiments were performed in a collaboration work between JNC and the Institute of Physics and Power Engineering of Russia to dispose Russian surplus weapons plutonium, focusing on the effect of the introduction of uranium-plutonium mixed-dioxide (MOX) fuel and stainless steel reflector into the current BN-600 core that is comprised of UO_2 fuel and blanket. The analysis results agreed well with measured values on most of the nuclear characteristics. The accuracies are comparable to those obtained for the conventional MOX fueled fast reactors. It suggests that the JNC analysis system can analyze accurately nuclear characteristics in uranium fueled cores as well. A significant improvement was achieved on the sodium void reactivity by employing an ultra fine group cell calculation system. A ...

International Nuclear Information System (INIS)

Uranium-aluminum alloys with a significant enrichment of uranium with "2"3"3U or "2"3"5U serve as nuclear fuels in research reactors. The quality assurance of this fuel requires, among other things, precise knowledge that all trace metal constituents that affect neutron economy, fuel integrity, and fuel fabrication process parameters are well within the specification limits. Trace metal characterization of "2"3"5U-Al alloy has been carried out by atomic spectrometry. The trace metal constituents of interest are grouped into common metals (silver, boron, calcium, cadmium, cobalt, chromium, copper, iron, magnesium, manganese, molybdenum, sodium, nickel, lead, silicon, tin, titanium, vanadium, tungsten, and zinc) and lanthanides (cerium, dysprosium, europium, gadolinium, holminium, lutetium, samarium, and terbium). The elements yttrium and zirconium are grouped with the latter in view of the chemical separation procedure used. The alloy samples ...

International Nuclear Information System (INIS)

This report primarily deals with three issues: the health consequences of the use of ammunition with depleted uranium cores; the health damage that radar staff may have suffered through stray X-radiation; and the way hazardous materials such as asbestos are handled in the German army. As regards uranium ammunition, the present findings suggest that there is neither reason for concern nor blame on anyone. The 31,000 American DU rounds that were fired over Kosovo in 1999 neither pose a health hazard to soldiers nor to the civil population. All that remains is a minimal risk of future groundwater contamination. The radar equipment currently in use in the German army poses no danger to operators, inspectors, service personnel or instructors provided that the relevant safety rules are observed. However, this cannot be said with the same degree of certainty with regard to the equipment used in the 1960s and 1970s. It is quite possible that ...

Energy Technology Data Exchange (ETDEWEB)

The untreated, heat- and alkali-treated Lentinus sajor-caju mycelia were used for the recovery of uranium from aqueous solutions. The effect of pH, temperature, initial concentration of UO{sub 2} {sup 2+} ions and contact time parameters were investigated in a batch system. The particles sizes of the fungal mycelia were ranging from 100 to 200 {mu}m. Biosorption equilibriums were established in about 30 min and the correlation regression coefficients show that the adsorption process can be well defined by the Freundlich equation. The alkali treated form had a high biosorption capacity (378 mg/g) than those of the untreated (268 mg/g) and heat-treated fungal mycelia (342 mg/g). Optimum biosorption was observed at pH 4.5 for all the tested fungal preparations and was independent of temperature (5-35 deg. C). In addition, the polarity and surface energy of the fungal biomass film preparations were determined by contact angle measurement. The fungal biomass could be ...

International Nuclear Information System (INIS)

In conducting aircraft surveys for uranium, it is found that temperature inversions can give spurious results because they promote accumulation of radon gas in the atmosphere. The "2"1"4Bi (daughter product of radon) gamma-rays detected from the atmosphere-borne radon are difficult to separate from the "2"1"4Bi gamma-rays originating from the ground, and providing a signature for uranium deposits. The purpose of the present study was to examine the feasibility of making remote temperature soundings of the atmosphere below a low-flying aircraft (140 m or less above ground) by the inversion of radiance measurements taken in the 15-micron carbon dioxide absorption band. Such measurements would identify those temperature inversion conditions possibly leading to an unacceptably large background of gamma-rays from the atmospheric radon. Thus, the incidence of spurious aerial survey data could be greatly reduced. An atmospheric model was set up and ...

International Nuclear Information System (INIS)

This study describes the mechanical compatibility of the direct use of spent pressurized water reactor (PWR) fuel in Canada deuterium uranium (CANDU) reactors (DUPIC) fuel, when it is loaded into a CANDU reactor. The mechanical compatibility can be assessed for the fuel management, primary heat transport system, fuel channel, and the fuel handling system in the reactor core by both the experimental and analytic methods. Because the physical dimensions of the DUPIC fuel bundle adopt the CANDU flexible (CANFLEX) fuel bundle design which has already been demonstrated for a commercial use in CANDU reactors, the experimental compatibility analyses focused on the generation of material property data and the irradiation tests of the DUPIC fuel, which are used for the computational analysis. The intermediate results of the mechanical compatibility analysis have shown that the integrity of the DUPIC fuel is mostly maintained under the high power and high burnup conditions ...

International Nuclear Information System (INIS)

LLNL is developing the nuclear fusion based Laser Inertial Fusion Energy (LIFE) power plant concept. The baseline design uses a depleted uranium (DU) fission fuel blanket with a flowing molten salt coolant (flibe) that also breeds the tritium needed to sustain the fusion energy source. Indirect drive targets, similar to those that will be demonstrated on the National Ignition Facility (NIF), are ignited at #approx#13 Hz providing a 500 MW fusion source. The DU is in the form of a uranium oxycarbide kernel in modified TRISO-like fuel particles distributed in a carbon matrix forming 2-cm-diameter pebbles. The thermal power is held at 2000 MW by continuously varying the "6Li enrichment in the coolants. There are many options to be considered in the engine design including target yield, U-to-C ratio in the fuel, fission blanket thickness, etc. Here we report results of design variations and compare them in terms of various figures of merit such as ...

Energy Technology Data Exchange (ETDEWEB)

Monitoring of groundwater quality from boreholes in and around the former Yotsugi open-pit mining site in the Ningyo-toge Environmental Engineering Center, JNC, have been carried out to estimate extent and quality of contaminated water plume from the buried heap-leaching residue. In this report, data collected from 1979 to 1998 fiscal year were listed and their spatial and time variation of physicochemical parameters, uranium and radium were also summarized. Additionally, groundwater sampler has been improved and analytical method has been modified. Some results from groundwater quality were; 1. Generally, electric conductivity and concentrations of uranium and radium outside of the site tend to lower than one from the inside area. 2. Data from borehole No. 13, installed outside of the site, exceptionally little higher than one from the inside area. (author)

Energy Technology Data Exchange (ETDEWEB)

Pacific Northwest Laboratory (PNL) is investigating the use of a rock armoring blanket (riprap) to mitigate wind and water erosion of an earthen radon suppression cover applied to uranium mill tailings. Because the radon suppression cover and the tailings must remain intact for up to 1000 years or longer, the riprap must withstand natural weathering forces. This report is a review of information on rock weathering and riprap durability. Chemical and physical weathering processes, rock characteristics related to durability, climatic conditions affecting the degree and rate of weathering, and testing procedures used to measure weathering susceptibilities have been reviewed. Sampling and testing techniques, as well as analyses of physical and chemical weathering susceptibilities, are necessary to evaluate rock durability. Many potential riprap materials may not be able to survive 1000 years of weathering. Available techniques for durability testing cannot adequately ...

International Nuclear Information System (INIS)

We provide a detailed overview of an on-going, multinational test programme that is developing aerosol data for some spent fuel sabotage scenarios on spent fuel transport and storage casks. Experiments are being performed to quantify the aerosolised materials plus volatilised fission products generated from actual spent fuel and surrogate material test rods, due to impact by a high-energy/density device. The programme participants in the United States plus Germany, France and the United Kingdom, part of the international Working Group for Sabotage Concerns of Transport and Storage Casks (WGSTSC) have strongly supported and coordinated this research programme. Sandia National Laboratories has the lead role for conducting this research programme; test programme support is provided by both the US Department of Energy and the US Nuclear Regulatory Commission. We provide a summary of the overall, multiphase test design and a description of all explosive containment and aerosol collection ...

International Nuclear Information System (INIS)

The authors provide a detailed overview of an on-going, multinational test program that is developing aerosol data for some spent fuel sabotage scenarios on spent fuel transport and storage casks. Experiments are being performed to quantify the aerosolized materials plus volatilized fission products generated from actual spent fuel and surrogate material test rods, due to impact by a high-energy-density device. The program participants in the United States plus Germany, France and the United Kingdom, part of the international Working Group for Sabotage Concerns of Transport and Storage Casks (WGSTSC) have strongly supported and coordinated this research program. Sandia National Laboratories has the lead role for conducting this research program; test program support is provided by both the US Department of Energy and the US Nuclear Regulatory Commission. The authors provide a summary of the overall, multiphase test design and a description of all explosive containment and aerosol ...

Energy Technology Data Exchange (ETDEWEB)

A series of experiments involving high explosives and radioactive materials were conducted at Los Alamos, New Mexico, primarily to understand certain safety aspects of operational nuclear weapons. The experiments were conducted underground in large diameter holes as deep as 120 ft. The location was selected because it had geologic and hydrologic characteristics that assured complete containment of the experiments and precluded any possible contamination of groundwater. Important features verified by the USGS included the absence of any recharge and about 1200 feet of dry rock above the groundwater aquifer. Residual materials dispersed by detonation of the high explosives remain at the bottom of the experimental holes. The materials of significance from an environmental standpoint include about 40 kg of plutonium, 93 kg of enriched uranium, at least 82 kg of depleted uranium, 13 kg of beryllium, and an undetermined amount of lead. Environmental ...

Energy Technology Data Exchange (ETDEWEB)

The fuel composition heterogeneity effect on reactor performance parameters was assessed by refueling simulations for three DUPIC fuel options of fuel composition heterogeneity control: the fissile content adjustment, the reactivity control by slightly enriched and depleted uranium, and the reactivity control by natural uranium. For each DUPIC fuel option, the simulations were performed using 30 heterogeneous fuel types which were determined by the agglomerative hierarchical clustering method. The heterogeneity effect was considered during the refueling simulation by randomly selecting fuel types for the refueling operation. The refueling simulations of the heterogeneous core have shown that the key performance parameters such as the maximum channel power (MCP), maximum bundle power (MBP), and channel power peaking factor (CPPF) are close to those of the core that has single fuel type. For the three DUPIC fuel options, the uncertainties of MCP, ...

Energy Technology Data Exchange (ETDEWEB)

The paper presents the preparation, X-ray powder diffraction data as well as some magnetic and spectroscopic properties of a new uranium(III) complex bromide of the formula NH{sub 4}UBr{sub 4}.1.5CH{sub 3}CN.6H{sub 2}O. The compound crystallizes in the monoclinic system with a=11.877 A, b=6.385 A, c=6.815 A, {beta}=101.29deg and Z=2. In the 60-240 K range it follows the Curie-Weiss law with {theta}=-37.24 K and {mu}{sub eff}=3.20 B.M. The IR and UV-VIS absorption spectra were recorded in the 80-4000 cm{sup -1} and 4000-26000 cm{sup -1} spectral ranges respectively. Thermal decomposition at a non-static high vacuum enabled the conversion of the compound into pure and anhydrous UBr{sub 3}. (orig.).

International Nuclear Information System (INIS)

This report presents a comparison of the characteristics of some prominent examples of independent government corporations and agencies with respect to the Department of Energy's (DOE) uranium enrichment enterprise. The six examples studied were: the Bonneville Power Administration (BPA); the Tennessee Valley Authority (TVA); the Synthetic Fuels Corporation (SYNFUELS); the Consolidated Rail Corporation (CONRAIL); the British Telecommunications Corporation (British TELECOM); and the Communications Satellite Organization (COMSAT), in order of decreasing levels of government ownership and control. They range from BPA, which is organized as an agency within DOE, to COMSAT, which is privately owned and free from almost all regulations common to government agencies. Differences in the degree of government involvement in these corporations and in many other characteristics serve to illustrate that there are no accepted standards for defining the characteristics of ...

Energy Technology Data Exchange (ETDEWEB)

The President`s budget request for FY 1994 included a construction project for the Advanced Neutron Source (ANS). However, the budget that emerged from the Congress did not, and so activities during this reporting period were limited to continued research and development and to advanced conceptual design. A significant effort was devoted to a study, requested by the US Department of Energy (DOE) and led by Brookhaven National Laboratory, of the performance and cost impacts of reducing the uranium fuel enrichment below the baseline design value of 93%. The study also considered alternative core designs that might mitigate those impacts. The ANS Project proposed a modified core design, with three fuel elements instead of two, that would allow operation with only 50% enriched uranium and use existing fuel technology. The performance penalty would be 15--20% loss of thermal neutron flux; the flux would still just meet the minimum design requirement ...

International Nuclear Information System (INIS)

Secondary ion mass spectrometry (SIMS), secondary electron microscopy (SEM) and X-ray analysis have been applied to the measurement of U-bearing particles with the intent of gleaning information concerning their history and/or origin. The lead isotopic abundances are definitive indicators that U-bearing particles have come from an ore-body, even if they have undergone chemical processing. SEM images and X-ray analysis can add further information to the study that may allude to the extent of chemical processing. The presence of 'common' lead that does not exhibit a radiogenic signature is clear evidence of anthropogenic origin. (author)

Energy Technology Data Exchange (ETDEWEB)

In acute intoxication, uranium (U) not only inhibits bone formation but its excretion in urine also causes renal damage. The former effect is ameliorated by tetracycline (TC), probably due to its chelation property, which might also prevent U deposition in bone. Chemical determination of U incorporated in bone and a histological study of the kidneys were performed on animals injected with U and then treated with TC. The results showed that TC was unable to prevent the binding of U to bone while it exacerbated U-induced renal damage.