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Sample records for actinide level density

  1. Level Densities in the actinide region and indirect n,y cross section measurements using the surrogate method

    Wiedeking M.

    2012-02-01

    Full Text Available Results from a program of measurements of level densities and gamma ray strength functions in the actinide region are presented. Experiments at the Oslo cyclotron involving the Cactus/Siri detectors and 232Th(d,x and 232Th(3He,x reactions were carried out to help answer the question of which level density model is the most appropriate for actinide nuclei, since it will have an impact on cross section calculations important for reactor physics simulations. A new technique for extracting level densities and gamma ray strength functions from particle-gamma coincidence data is proposed and results from the development of this technique are presented. In addition, simultaneous measurements of compound nuclear gamma decay probabilities have been performed for the key thorium cycle nuclei 233Th, 231Th and 232Pa up to around 1MeV above the neutron binding energy and have enabled extraction of indirect neutron induced capture cross sections for the 232Th, 231Pa and 230Th nuclei using the surrogate reaction method. Since the neutron capture cross section for 232Th is already well known from direct measurements a comparison provides a stringent test of the applicability of the surrogate technique in the actinide region.

  2. Level Densities in the actinide region and indirect n,y cross section measurements using the surrogate method

    Wilson, J. N.; Gunsing, F.; Bernstein, L.; Bürger, A.; Görgen, A.; Thompson, I. J.; Guttormssen, M.; Larsen, A.-C.; Mansouri, P.; Renstrøm, T.; Rose, S. J.; Siem, S.; Wiedeking, M.; Wiborg, T.

    2012-02-01

    Results from a program of measurements of level densities and gamma ray strength functions in the actinide region are presented. Experiments at the Oslo cyclotron involving the Cactus/Siri detectors and 232Th(d,x) and 232Th(3He,x) reactions were carried out to help answer the question of which level density model is the most appropriate for actinide nuclei, since it will have an impact on cross section calculations important for reactor physics simulations. A new technique for extracting level densities and gamma ray strength functions from particle-gamma coincidence data is proposed and results from the development of this technique are presented. In addition, simultaneous measurements of compound nuclear gamma decay probabilities have been performed for the key thorium cycle nuclei 233Th, 231Th and 232Pa up to around 1MeV above the neutron binding energy and have enabled extraction of indirect neutron induced capture cross sections for the 232Th, 231Pa and 230Th nuclei using the surrogate reaction method. Since the neutron capture cross section for 232Th is already well known from direct measurements a comparison provides a stringent test of the applicability of the surrogate technique in the actinide region.

  3. Self-interaction corrected local spin density calculations of actinides

    Petit, Leon; Svane, Axel; Szotek, Z;

    2010-01-01

    We use the self-interaction corrected local spin-density approximation in order to describe localization-delocalization phenomena in the strongly correlated actinide materials. Based on total energy considerations, the methodology enables us to predict the ground-state valency configuration of the...

  4. Actinides and fission products partitioning from high level liquid waste

    The presence of small amount of mixed actinides and long-lived heat generators fission products as 137Cs and 90Sr are the major problems for safety handling and disposal of high level nuclear wastes. In this work, actinides and fission products partitioning process, as an alternative process for waste treatment is proposed. First of all, ammonium phosphotungstate (PWA), a selective inorganic exchanger for cesium separation was chosen and a new procedure for synthesizing PWA into the organic resin was developed. An strong anionic resin loaded with tungstate or phosphotungstate anion enables the precipitation of PWA directly in the resinous structure by adding the ammonium nitrate in acid medium (R-PWA). Parameters as W/P ratio, pH, reactants, temperature and aging were studied. The R-PWA obtained by using phosphotungstate solution prepared with W/P=9.6, 9 hours digestion time at 94-106 deg C and 4 to 5 months aging time showed the best capacity for cesium retention. On the other hand, Sr separation was performed by technique of extraction chromatography, using DH18C6 impregnated on XAD7 resin as stationary phase. Sr is selectively extracted from acid solution and >99% was recovered from loaded column using distilled water as eluent. Concerning to actinides separations, two extraction chromatographic columns were used. In the first one, TBP(XAD7) column, U and Pu were extracted and its separations were carried-out using HNO3 and hydroxylamine nitrate + HNO3 as eluent. In the second one, CMP0-TBP(XAD7) column, the actinides were retained on the column and the separations were done by using (NH4)2C2O4 , DTPA, HNO3 and HCl as eluent. The behavior of some fission products were also verified in both columns. Based on the obtained data, actinides and fission products Cs and Sr partitioning process, using TBP(XAD7) and CMP0-TBP(XAD7) columns for actinides separation, R-PWA column for cesium retention and DH18C6(XAD7) column for Sr isolation was performed. (author)

  5. Tables of nuclear level density parameters

    The Renormalized Gas Model (RGM) has been used to calculate single particle level density parameters for more than 2000 nucleides over the range 9<=Z<=126 (15<=A<=338). Three separate tables present the elements on or near the valley of beta stability, neutron-rich fission fragment nucleides, and transitional nuclei, actinides and light-mass super heavy elements. Each table identifies the nucleus in terms of Z and N and presents the RGM deformation energy of binding, the total RGM structural energy correction over the free gas Fermi surface, and the level density parameter

  6. Nuclear level density predictions

    Bucurescu Dorel; von Egidy Till

    2015-01-01

    Simple formulas depending only on nuclear masses were previously proposed for the parameters of the Back-Shifted Fermi Gas (BSFG) model and of the Constant Temperature (CT) model of the nuclear level density, respectively. They are now applied for the prediction of the level density parameters of all nuclei with available masses. Both masses from the new 2012 mass table and from different models are considered and the predictions are discussed in connection with nuclear regions most affected ...

  7. Nuclear level density

    Experimental data show that the number of nuclear states increases rapidly with increasing excitation energy. The properties of highly excited nuclei are important for many nuclear reactions, mainly those that go via processes of the compound nucleus type. In this case, it is sufficient to know the statistical properties of the nuclear levels. First of them is the function of nuclear levels density. Several theoretical models which describe the level density are presented. The statistical mechanics and a quantum mechanics formalisms as well as semi-empirical results are analysed and discussed. (Author)

  8. Selective extraction of actinides from high level liquid wastes. Study of the possibilities offered by the Redox properties of actinides

    Partitioning of high level liquid wastes coming from nuclear fuel reprocessing by the PUREX process, consists in the elimination of minor actinides (Np, Am, and traces of Pu and U). Among the possible processes, the selective extraction of actinides with oxidation states higher than three is studied. First part of this work deals with a preliminary step; the elimination of the ruthenium from fission products solutions using the electrovolatilization of the RuO4 compound. The second part of this work concerns the complexation and oxidation reactions of the elements U, Np, Pu and Am in presence of a compound belonging to the insaturated polyanions family: the potassium phosphotungstate. For actinide ions with oxidation state (IV) complexed with phosphotungstate anion the extraction mechanism by dioctylamine was studied and the use of a chromatographic extraction technic permitted successful separations between tetravalents actinides and trivalents actinides. Finally, in accordance with the obtained results, the basis of a separation scheme for the management of fission products solutions is proposed

  9. Fission level density and barrier parameters for actinide neutron-induced cross section calculations. Final report of research contract 8832/RB. Time period covered: 15 December 1995 - 14 June 1998

    Fission and total level densities modelling approach was developed. Neutron-induced fission cross section data for incident energies from 10 keV up to emissive fission threshold were employed to extract level density and fission barrier parameters. In particular, fission barrier parameters (inner barrier height, outer barrier height, curvatures) were extracted for altogether 49 isotopes of Th, Pa, U, Np, Pu, Am, Cm, Bk, and Cf. The adopted level density modelling approach and fission barrier parametrization was supported by calculations of fission cross section data above the emissive fission threshold, up to 20 MeV neutron incident energy. (author)

  10. Partial level densities

    Methods for calculating partial level densities for use in pre-equilibrium model calculations are described. The RIPL Starter File includes a Fortran code avrigeanu.for by M. Avrigeanu for using various equidistant and Fermi-gas single-particle models, including models that incorporate pairing and shell effects within closed-form treatments and a Fortran code capote-micro.for by R. Capote, which uses a microscopic theory based on a convolution of shell-model single-particle states with BCS pairing. (author)

  11. Density functional theory calculations of the redox potentials of actinide(VI)/actinide(V) couple in water

    The measured redox potential of an actinide at an electrode surface involves the transfer of a single electron from the electrode surface on to the actinide center. Before electron transfer takes place, the complexing ligands and molecules of solvation need to become structurally arranged such that the electron transfer is at its most favorable. Following the electron transfer, there is further rearrangement to obtain the minimum energy structure for the reduced state. As such, there are three parts to the total energy cycle required to take the complex from its ground state oxidized form to its ground state reduced form. The first part of the energy comes from the structural rearrangement and solvation energies of the actinide species before the electron transfer or charge transfer process; the second part, the energy of the electron transfer; the third part, the energy required to reorganize the ligands and molecules of solvation around the reduced species. The time resolution of electrochemical techniques such as cyclic voltammetry is inadequate to determine to what extent bond and solvation rearrangement occurs before or after electron transfer; only for a couple to be classed as reversible is it fast in terms of the experimental time. Consequently, the partitioning of the energy theoretically is of importance to obtain good experimental agreement. Here we investigate the magnitude of the instantaneous charge transfer through calculating the fast one electron reduction energies of AnO2(H2O)n2+, where An = U, Np, and Pu, for n = 4-6, in solution without inclusion of the structural optimization energy of the reduced form. These calculations have been performed using a number of DFT functionals, including the recently developed functionals of Zhao and Truhlar. The results obtained for calculated electron affinities in the aqueous phase for the AnO2(H2O)52+/+ couples are within 0.04 V of accepted experimental redox potentials, nearly an order of magnitude

  12. Isopiestic density law of actinide nitrates applied to criticality calculations

    Up to now, criticality safety experts used density laws fitted on experimental data and applied them in and outside the measurement range. Depending on the case, such an approach could be wrong for nitrate solutions. Seven components are concerned: UO2(NO3)2, U(NO3)4, Pu(NO3)4, Pu(NO3)3, Th(NO3)4, Am(NO3)3 and HNO3. To get rid of this problem, a new methodology based on the thermodynamic concept of binary electrolytes solutions mixtures at constant water activity, so called 'isopiestic' solutions, has been developed by IRSN to calculate the nitrate solutions density. This article shortly presents the theoretical aspects of the method, its qualification using benchmarks and its implementation in IRSN graphical user interface. (author)

  13. Experimental level-structure determination in odd-odd actinide nuclei

    The status of experimental determination of level structure in odd-odd actinide nuclei is reviewed. A technique for modeling quasiparticle excitation energies and rotational parameters in odd-odd deformed nuclei is applied to actinide species where new experimental data have been obtained by use of neutron-capture gamma-ray spectroscopy. The input parameters required for the calculation are derived from empirical data on single-particle excitations in neighboring odd-mass nuclei. Calculated configuration-specific values for the Gallagher-Moszkowski splittings are used. Calculated and experimental level structures for 238Np, 244Am, and 250Bk are compared, as well as those for several nuclei in the rare-earth region. The agreement for the actinide species is excellent, with bandhead energies deviating 22 keV and rotational parameters 5%, on the average. Applications of this modeling technique are discussed

  14. Strontium and Actinide Separations from High Level Nuclear Waste Solutions using Monosodium Titanate - Actual Waste Testing

    Peters, T.B.; Barnes, M.J.; Hobbs,D.T.; Walker, D.D.; Fondeur, F.F.; Norato, M.A.; Pulmano, R.L.; Fink, S.D.

    2005-11-01

    Pretreatment processes at the Savannah River Site will separate {sup 90}Sr, alpha-emitting and radionuclides (i.e., actinides) and {sup 137}Cs prior to disposal of the high-level nuclear waste. Separation of {sup 90}Sr and alpha-emitting radionuclides occurs by ion exchange/adsorption using an inorganic material, monosodium titanate (MST). Previously reported testing with simulants indicates that the MST exhibits high selectivity for strontium and actinides in high ionic strength and strongly alkaline salt solutions. This paper provides a summary of data acquired to measure the performance of MST to remove strontium and actinides from actual waste solutions. These tests evaluated the effects of ionic strength, mixing, elevated alpha activities, and multiple contacts of the waste with MST. Tests also provided confirmation that MST performs well at much larger laboratory scales (300-700 times larger) and exhibits little affinity for desorption of strontium and plutonium during washing.

  15. Actinide chemistry using singlet-paired coupled cluster and its combinations with density functionals

    Garza, Alejandro J; Scuseria, Gustavo E

    2015-01-01

    Singlet-paired coupled cluster doubles (CCD0) is a simplification of CCD that relinquishes a fraction of dynamic correlation in order to be able to describe static correlation. Combinations of CCD0 with density functionals that recover specifically the dynamic correlation missing in the former have also been developed recently. Here, we assess the accuracy of CCD0 and CCD0+DFT (and variants of these using Brueckner orbitals) as compared to well-established quantum chemical methods for describing ground-state properties of singlet actinide molecules. The $f^0$ actinyl series (UO$_2^{2+}$, NpO$_2^{2+}$, PuO$_2^{2+}$), the isoelectronic NUN, and Thorium (ThO, ThO$^{2+}$) and Nobelium (NoO, NoO$_2$) oxides are studied.

  16. Level densities in nuclear physics

    In the independent-particle model nucleons move independently in a central potential. There is a well-defined set of single- particle orbitals, each nucleon occupies one of these orbitals subject to Fermi statistics, and the total energy of the nucleus is equal to the sum of the energies of the individual nucleons. The basic question is the range of validity of this Fermi gas description and, in particular, the roles of the residual interactions and collective modes. A detailed examination of experimental level densities in light-mass system is given to provide some insight into these questions. Level densities over the first 10 MeV or so in excitation energy as deduced from neutron and proton resonances data and from spectra of low-lying bound levels are discussed. To exhibit some of the salient features of these data comparisons to independent-particle (shell) model calculations are presented. Shell structure is predicted to manifest itself through discontinuities in the single-particle level density at the Fermi energy and through variatons in the occupancy of the valence orbitals. These predictions are examined through combinatorial calculations performed with the Grover [Phys. Rev., 157, 832(1967), 185 1303(1969)] odometer method. Before the discussion of the experimenta results, statistical mechanical level densities for spherical nuclei are reviewed. After consideration of deformed nuclei, the conclusions resulting from this work are drawn. 7 figures, 3 tables

  17. STRONTIUM AND ACTINIDE SEPARATIONS FROM HIGH LEVEL NUCLEAR WASTE SOLUTIONS USING MONOSODIUM TITANATE 1. SIMULANT TESTING

    HOBBS, D. T.; BARNES, M. J.; PULMANO, R. L.; MARSHALL, K. M.; EDWARDS, T. B.; BRONIKOWSKI, M. G.; FINK, S. D.

    2005-04-14

    High-level nuclear waste produced from fuel reprocessing operations at the Savannah River Site (SRS) requires pretreatment to remove {sup 137}Cs, {sup 90}Sr and alpha-emitting radionuclides (i.e., actinides) prior to disposal. Separation processes planned at SRS include caustic side solvent extraction, for {sup 137}Cs removal, and ion exchange/sorption of {sup 90}Sr and alpha-emitting radionuclides with an inorganic material, monosodium titanate (MST). The predominant alpha-emitting radionuclides in the highly alkaline waste solutions include plutonium isotopes {sup 238}Pu, {sup 239}Pu and {sup 240}Pu. This paper provides a summary of data acquired to measure the performance of MST to remove strontium and actinides from simulated waste solutions. These tests evaluated the influence of ionic strength, temperature, solution composition and the oxidation state of plutonium.

  18. New density functional theory approaches for enabling prediction of chemical and physical properties of plutonium and other actinides.

    Mattsson, Ann Elisabet

    2012-01-01

    Density Functional Theory (DFT) based Equation of State (EOS) construction is a prominent part of Sandia's capabilities to support engineering sciences. This capability is based on amending experimental data with information gained from computational investigations, in parts of the phase space where experimental data is hard, dangerous, or expensive to obtain. A prominent materials area where such computational investigations are hard to perform today because of limited accuracy is actinide and lanthanide materials. The Science of Extreme Environment Lab Directed Research and Development project described in this Report has had the aim to cure this accuracy problem. We have focused on the two major factors which would allow for accurate computational investigations of actinide and lanthanide materials: (1) The fully relativistic treatment needed for materials containing heavy atoms, and (2) the needed improved performance of DFT exchange-correlation functionals. We have implemented a fully relativistic treatment based on the Dirac Equation into the LANL code RSPt and we have shown that such a treatment is imperative when calculating properties of materials containing actinides and/or lanthanides. The present standard treatment that only includes some of the relativistic terms is not accurate enough and can even give misleading results. Compared to calculations previously considered state of the art, the Dirac treatment gives a substantial change in equilibrium volume predictions for materials with large spin-orbit coupling. For actinide and lanthanide materials, a Dirac treatment is thus a fundamental requirement in any computational investigation, including those for DFT-based EOS construction. For a full capability, a DFT functional capable of describing strongly correlated systems such as actinide materials need to be developed. Using the previously successful subsystem functional scheme developed by Mattsson et.al., we have created such a functional. In

  19. Investigations of actinides in the context of final disposal of high-level radioactive waste - trivalent actinides in aqueous solution

    This contribution presents a small piece of research work at KIT-INE dealing with the speciation of redox sensitive trivalent actinides like Pu(III), Np(III), and U(III) in aqueous solution. The redox preparation, stabilization, and speciation of trivalent actinide in aqueous systems are discussed here. The reductants investigated were rongalite, HYA (hydroxylamine hydrochloride), and AHA (acetohydroxamic acid). The time dependence of An(III) stability at different pH values was investigated. The An(III) species in aqueous solution have been characterized by UV-Vis and XANES spectroscopy. A broader overview of the work at KIT-INE is given in the oral presentation at the NUCAR2013 conference. (author)

  20. Investigations of actinides in the context of final disposal of high-level radioactive waste. Trivalent actinides in aqueous solution

    The speciation of redox sensitive trivalent actinides Pu(III), Np(III), and U(III) has been studied in aqueous solution. The redox preparation, stabilization, and speciation of these trivalent actinides in aqueous systems are discussed here. The reductants investigated were rongalite, hydroxylamine hydrochloride, and acetohydroxamic acid and the An(III) species have been characterized by UV-Vis and XANES spectroscopy. The results show that the effectiveness of stabilization decreases generally in the order Pu(III) > Np(III) > U(III) and that the effectiveness of each reducing agent depends on the experimental conditions. More than 80 % of Pu(III) aquo species have been stabilized up to pH 5.5, whereas the Np(III) aquo ion could be stabilized in a pH range 0-2.5, and U(III) aquo ion is sufficiently stable at pH 1.0 and below over time periods suitable for experiments. However, this study gives a basis for the characterisation of the trivalent lighter actinides involved in complexation, sorption, and solid formation reactions in the future. (author)

  1. R and D for actinide partitioning and recovery of valuables from high level waste using radiotracers

    In the context of growing world population with rapidly increasing energy needs and the threat of global warming due to CO2 emission (caused by fossil fuel burning), the nuclear energy may be an attractive option particularly in the developing countries. Recycling of fuel is a unique feature of nuclear power technology which makes it a favourable choice with respect to conservation of energy resources. Steady growth of global fuel reprocessing activities (6000 tHM/annum) implies a vital role of separation science in developing efficient procedures for the separation and purification of actinides and in devising safe procedures for the management of nuclear waste arising at different stages of the PUREX process. High Level Waste (HLW) comprising of the concentrate of the raffinate of the co-extraction cycle (with over 95% of the total radioactivity produced in the burn up process in reactor) need to be isolated from the biosphere. There is a consensus among the waste management technologists that the safest route to achieve this, is to deposit it in a stable geological formation after it's immobilization in suitable glass/Synroc matrix. It ensures that any risk from exposure due to accidental intervention or natural disturbance is minimized. Risk perception is essentially due to the large radiological toxicity associated with alpha emitters like 237Np, 241Am, 243Am and 245Cm. Isotopes of Pu (left unrecovered) present in HLW also contribute towards radiological toxicity. In view of the high cost involved and the need for continuous surveillance, several countries are considering modifying their reprocessing schemes to partition (isolate) long-lived actinides from HLW. Since the volume of the actinide oxides (which retain major fraction of the radio toxicity of HLW) is significantly lower as compared to the other metal oxides present in HLW, such an approach is expected to reduce the cost of immobilization as well as of disposal (in geological repository) and

  2. Evaluation of chelation concentration and cation separation of actinides at ultra-trace levels in urine matrix

    The feasibility of measuring picogram levels of actinides in a urine matrix using ion chromatography coupled on-line to an inductively coupled plasma quadrupole mass spectrometer (IC-Q-ICPMS) was investigated. A chelation column for separation of matrix ions and preconcentration of the actinides was combined with a cation-exchange column for separation of the actinides. Sample preparation required simple addition of ammonium acetate to adjust the pH of the urine matrix. Spike solutions containing 232Th, 237Np, 238U, 239Pu, and 241Am were added to undiluted urine, diluted urine (1 : 9) and water. This approach enhanced the signal sensitivities of all the tested actinides over two orders of magnitude in the water matrix, while certain elements (especially Am) can still be effectively concentrated in undiluted urine. (author)

  3. Partitioning of actinides from high-level waste streams of Purex process using mixtures of CMPO and TBP in dodecane

    The extraction of actinides from high active aqueous raffinate waste (HAW) as well as high-level waste (HLW) solutions arising from Purex processing of thermal reactor fuels has been studied using a mixture of octyl(phenyl)-N,N-diisobutylcarbamoyl-methylphosphine oxide (CMPO) and TBP in dodecane. The results on the extraction and stripping of actinides, lanthanides, and other fission products are discussed. Optimum conditions are proposed for the efficient recovery of residual actinides from HAW and HLW streams by CMPO extraction followed by their selective stripping with suitable reagents. Experiments on the extraction and separation of actinides and lanthanides by CMPO in the presence of TBP in dodecane have also been carried out with U(VI) and Nd(III) to arrive at the limiting conditions for avoiding third-phase formation

  4. Extraction of actinides from high level waste streams of purex process using mixtures of CMPO and TBP in dodecane

    The extraction of actinides from high-active aqueous raffinate waste (HAW) as well as high level waste (HLW) solutions arising from Purex processing of thermal reactor fuels has been studied using a mixture of octyl(phenyl)-N, N-diisobutylcarbamoylmethylphosphine oxide (CMPO) and TBP in dodecane. The results on the extraction and striping of actinides, lanthanides and other fission products have been discussed in this report and optimum conditions have been proposed for the efficient recovery of residual actinides from HAW and HLW streams by CMPO extraction and for their selective stripping with suitable reagents. Experiments on the extraction and separation of actinides and lanthanides by CMPO in the presence of TBP in dodecane have also been carried out with U(VI) and Nd(III) to arrive at the limiting conditions for avoiding third phase formation. (author). 18 refs., 5 figs., 10 tabs

  5. Plutonium, americium and other actinides on Belarus territory: source, levels, risks

    For Belarus it was showed that in result of falling during nuclear trials happened contamination of upper soil layer by transuranium elements with medium level of contamination for 239,240Pu 53±17 Bq/m2. After Chernobyl accident this characteristic equal 1.1· Bq/m2 on the south of Belarus. In result accident it was revealed 17 actinides. For Chernobyl falling was determined big contents of 241Pu that will lead to maximum value of 241Am in 2059, which will be more in 2,5 times than 239,240Pu

  6. Radium institute research on actinide separation from high-level waste. Review

    Development of efficient technologies for recovery of long-lived radionuclides from high-level wastes (HLW) is urgent for implementation of the promising management methods (transmutation and disposal), as well as for existing practice of HLW management. In Russia at 'Mayak' radiochemical plant since 1996 there has been in operation the industrial facility UE-35 which provides the recovery of cesium and strontium from HLW. The next stage is aimed at development and implementation of actinide separation technology from HLW. For this purpose the following four processes are studied and tested: processes based on chlorinated cobalt dicarbollide (ChCoDiC-process), isoamyldialkyl-phosphine oxide (POR-process), diphenyldibutylcarbamoylphosphine oxide (modified TRUEX-process) and mixture of ChCoDiC, carbamoylphosphine oxide (CMPO) and polyethylene glycol (PEG) (UNEX-process). After comprehensive study of extraction, physico-chemical and operational properties of selected extraction systems, testing of processes was conducted at test facilities with the use of actual or simulated HLW. Mixer-settlers and centrifugal contactors were used as extraction equipment in these tests. The test results show that the ChCoDiC-process can afford recovery of transplutonium and rare-earth elements (TPE and REE) from HLW and separation of them into fractions. POR-process and modified TRUEX-process enable to recover from HLW uranium, neptunium, plutonium, TPE, REE and technetium with the possibility for production of individual fractions. UNEX-process permits to attain simultaneous recovery of actinides, REE, cesium and strontium from HLW. During tests the potentialities of UNEX-process for obtaining such fractions as cesium, cesium+strontium and actinides+REE at stripping stage were demonstrated as well. (author)

  7. Actinide separation of high-level waste using solvent extractants on magnetic microparticles

    Polymeric-coated ferromagnetic particles 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 and plutonium from nuclear waste solutions. Due to their chemical nature, these extractants selectively complex americium and plutonium contaminants onto the particles, which can be recovered from the waste solution using a magnet. The effectiveness of the extractant-absorbed particles at removing transuranics (TRU) from simulated solutions and various nitric acid solutions was measured by gamma and liquid scintillation counting of plutonium and americium. The HNO3 concentration range was 0.01 M to 6M. The partition coefficients (Kd) for various actinides at 2M HNO3 were determined to be between 3,000 and 30,000. These values are larger than those projected for TRU recovery by traditional liquid/liquid extraction. Results from transmission electron microscopy indicated a large dependence of Kd on relative magnetite location within the polymer and the polymer surface area. Energy disperse spectroscopy demonstrated homogeneous metal complexation on the polymer surface with no metal clustering. The radiolytic stability of the particles was determined by using 60Co gamma irradiation under various conditions. The results showed that Kd more strongly depends on the nitric acid dissolution rate of the magnetite than the gamma irradiation dose. Results of actinide separation from simulated high-level waste representative of that at various DOE sites are also discussed

  8. Experimental level densities of atomic nuclei

    It is almost 80 years since Hans Bethe described the level density as a non-interacting gas of protons and neutrons. In all these years, experimental data were interpreted within this picture of a fermionic gas. However, the renewed interest of measuring level density using various techniques calls for a revision of this description. In particular, the wealth of nuclear level densities measured with the Oslo method favors the constant-temperature level density over the Fermi-gas picture. From the basis of experimental data, we demonstrate that nuclei exhibit a constant-temperature level density behavior for all mass regions and at least up to the neutron threshold. (orig.)

  9. Experimental level densities of atomic nuclei

    Guttormsen, M.; Bello Garrote, F.L.; Eriksen, T.K.; Giacoppo, F.; Goergen, A.; Hagen, T.W.; Klintefjord, M.; Larsen, A.C.; Nyhus, H.T.; Renstroem, T.; Rose, S.J.; Sahin, E.; Siem, S.; Tornyi, T.G.; Tveten, G.M. [University of Oslo, Department of Physics, Oslo (Norway); Aiche, M.; Ducasse, Q.; Jurado, B. [University of Bordeaux, CENBG, CNRS/IN2P3, B.P. 120, Gradignan (France); Bernstein, L.A.; Bleuel, D.L. [Lawrence Livermore National Laboratory, Livermore, CA (United States); Byun, Y.; Voinov, A. [Ohio University, Department of Physics and Astronomy, Athens, Ohio (United States); Gunsing, F. [CEA Saclay, DSM/Irfu/SPhN, Cedex (France); Lebois, L.; Leniau, B.; Wilson, J. [Institut de Physique Nucleaire d' Orsay, Orsay Cedex (France); Wiedeking, M. [iThemba LABS, P.O. Box 722, Somerset West (South Africa)

    2015-12-15

    It is almost 80 years since Hans Bethe described the level density as a non-interacting gas of protons and neutrons. In all these years, experimental data were interpreted within this picture of a fermionic gas. However, the renewed interest of measuring level density using various techniques calls for a revision of this description. In particular, the wealth of nuclear level densities measured with the Oslo method favors the constant-temperature level density over the Fermi-gas picture. From the basis of experimental data, we demonstrate that nuclei exhibit a constant-temperature level density behavior for all mass regions and at least up to the neutron threshold. (orig.)

  10. Bulk separation of actinides and lanthanides from actual high level liquid waste of PUREX origin using tetra-(2-ethylhexyl) diglycolamide

    Partitioning and transmutation of minor actinides is emerging as one of the preferred options for the management of high level liquid waste (HLLW) generated during the reprocessing of spent nuclear fuel. Various processes viz., DIAMEX process, TRUEX process etc. have been developed and are being tested for their use in actual application. Of late, a new class of extractant, diglycolamides, with good radiation and chemical stability and complete incinerability has emerged as the front runner for partitioning. This paper deals with the testing of indigenous and bulk synthesized N,N,N',N' tetra-(2-ethylhexyl) diglycolamide (TEHDGA) for the bulk separation of actinides and lanthanides (An and Ln) from actual HLLW

  11. Actinide recycle

    A multitude of studies and assessments of actinide partitioning and transmutation were carried out in the late 1970s and early 1980s. Probably the most comprehensive of these was a study coordinated by Oak Ridge National Laboratory. The conclusions of this study were that only rather weak economic and safety incentives existed for partitioning and transmuting the actinides for waste management purposes, due to the facts that (1) partitioning processes were complicated and expensive, and (2) the geologic repository was assumed to contain actinides for hundreds of thousands of years. Much has changed in the few years since then. A variety of developments now combine to warrant a renewed assessment of the actinide recycle. First of all, it has become increasingly difficult to provide to all parties the necessary assurance that the repository will contain essentially all radioactive materials until they have decayed. Assurance can almost certainly be provided to regulatory agencies by sound technical arguments, but it is difficult to convince the general public that the behavior of wastes stored in the ground can be modeled and predicted for even a few thousand years. From this point of view alone there would seem to be a clear benefit in reducing the long-term toxicity of the high-level wastes placed in the repository

  12. Extraction chromatographic separation of minor actinides from PUREX high-level wastes using CMPO

    An extraction chromatographic technique using octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) adsorbed on chromosorb-102 (CAC) has been tested as an alternative to the TRUEX solvent extraction process, where CMPO has been used as the extracting agent to recover minor actinides from high-activity waste (HAW) solutions of PUREX origin. The batchwise uptake behavior of U(VI), Pu(IV), Am(III), Eu(III), Zr(IV), Fe(III), Ru(III), and TcO4- from a nitric acid medium by CAC has been studied. The uptake of actinides and lanthanides are higher than those of other fission products and inert materials. The batchwise loading experiments in the presence of Nd(III)/U(VI) have shown that at lower concentrations of these metal ions, the uptake of Pu(IV), U(VI), and Am(III) are reasonably high. Studies on loading of Nd(III), U(VI), and Pu(IV) on a column containing 1.7 g of CAC have shown that Nd(III) (30 mg) and U(VI) (90 mg) could be loaded, while Pu(IV) (∼0.6) was loaded on a small column containing 100 mg of CAC without any break-through. Further, a synthetic HAW solution as such and the actual PUREX HAW solution, after depleting the uranium content by a 30% tributyl-phosphate contact, were loaded on a CAC column. The effluents did not contain any alpha activity above the background level. The activities could subsequently be eluted with 0.0.4 M HNO3 (americium and rare earths), 0.01 M oxalic acid (plutonium), and 0.25 M Na2CO3 [U(VI)]. The recoveries of these metal ions were found to be >99%

  13. Partial level densities for nuclear data calculations

    Avrigeanu, M

    1998-01-01

    The main formalisms of partial level densities (PLD) used in preequilibrium nuclear reaction models, based on the equidistant spacing model (ESM), are considered. A collection of FORTRAN77 functions for PLD calculation by using 14 formalisms for the related partial-state densities is provided and 28 sample cases (73 versions) are described. The results are given in graphic form too. Composite (recommended) formulas, which include the optional use of various corrections, i.e. the advanced pairing and shell correction in addition to the Pauli effect, and average energy-dependent single-particle level densities for the excited particles and holes, are also given. The formalism comprises the density of particle-hole bound states, and the effects of an exact correction for the Pauli-exclusion principle are considered. Keywords: Partial nuclear level density; Nuclear level density; Single-particle level density; Equidistant-spacing model; Preequilibrium emission; Nuclear reactions

  14. The effects of actinide separation on the radiological consequences of geologic disposal of high-level waste

    It has often been suggested that the potential hazard to man from the disposal of high-level radioactive waste could be reduced by removing a substantial fraction of the actinide elements. In this report the effects of actinide separation on the radiological consequences of one of the disposal options currently under consideration, that of burial in deep geologic formations, are examined. The results show that the potential radiological impact of geologic disposal of high-level waste arises from both long-lived fission products and actinides (and their daughter radionuclides). Neither class of radionuclides is of overriding importance and actinide separation would therefore reduce the radiological impact to only a limited extent and over limited periods. There might be a case for attempting to reduce doses from 237Np. To achieve this it appears to be necessary to separate both neptunium and its precursor element americium. However, there are major uncertainties in the data needed to predict doses from 237Np; further research is required to resolve these uncertainties. In addition, consideration should be given to alternative methods of reducing the radiological impact of geologic disposal. The conclusions of this assessment differ considerably from those of similar studies based on the concept of toxicity indices. Use of these indices can lead to incorrect allocation of research and development effort. (author)

  15. Actinides geochemical database for performance analysis of high-level radioactive waste repositories and the program to increase its confidence

    Japan Nuclear Cycle Development Institute (JNC) published a second progress report (H12 report) in 1999 to clarify the technical confidence of the concept and technical bases for site selection and safety standards for high-level radioactive waste (HLW) geological disposal and Japan. A law for HLW final disposal was legislated based on the knowledge of the H12 report and an implementing body was established in 2000 by the law. Thus the HLW disposal program in Japan has been entered into the implementation phase. The thermodynamic database (TDB) and the sorption database (SDB) for actinides have been developed in performance analysis of the H12 report. The TDB for actinides are based on reliable measurement data, a thermodynamic models and chemical analogy. The SDB for actinides was developed and selection of distribution coefficient (Kd) was carried out under consideration of repository conditions. The validity of these databases was checked through individual migration experiments. JNC has started the work program using the QUALITY' (Quantitative Assessment Radionuclide Migration Experiment Facility) since 1999, in which we have systematically obtained migration data for radionuclides including actinides under reducing conditions. This facility enables to supply the reliable migration data widely applicable in Japanese geological conditions. (author)

  16. Vibrational state contribution to nuclear level density

    The different simple methods for evaluation of vibrational enhancement factor of nuclear level density with allowance for collective state damping are considered and compared. A practical method for calculation of nuclear level density is recommended taking into account quadrupole and octupole vibrational states. (author)

  17. Uncertainties in exposures, contamination level and doses after inhalation of actinides

    In France, after occupational exposure to radioactive aerosols, committed doses are currently calculated by an ascending approach from biological data to estimate the initial contamination using dose per unit intake (DPUI). Specific DPUI can be calculated depending on the contamination. This paper is an overview on uncertainties in exposure level, biokinetics of radionuclides and doses after inhalation exposure to aerosol containing actinides. Data reported in the literature and those obtained in studies which are still in progress are described. A comparison of the uncertainties has been done after an ascending and a descending approach. In this later case, aerosol deposition within the respiratory tract is estimated from air sampling at the work place (estimate of the activity of the aerosol). The largest uncertainties were calculated after a descending application of the models. The results here reported pointed out the need of the knowledge of the uncertainties for a realistic interpretation of the results obtained after dose calculation, as well as the application limits of some ICRP models. Moreover, difficulties to estimate risk of cancer from doses are pointed out, which are mainly associated with the heterogeneity of the distribution of alpha dose within the different target regions of the respiratory tract. (authors)

  18. Decay calculations on medium-level and actinide-containing wastes from the LWR fuel cycle. Pt. 1

    A number of basic data on medium-level and actinide-containing waste streams from the LWR fuel cycle were evaluated and the activity and thermal decay power were calculated for the nuclide inventories of cladding hulls and fuel assembly structural materials, for feed clarification sludge, medium-level aqueous process waste, low-level solid transuranium waste and for medium-level reactor operating waste. The activity as a function of decay time of the medium-level wastes decreases within 500 to 600 years by 1 to 3 orders of magnitude and is at the same time about 1 to 2 orders of magnitude lower than the activity of the high-level waste. The thermal decay power of the medium-level wastes decreases after 10 to 100 years by about 3 orders of magnitude and is about a factor of 10 to 100 less than that of high-level waste. In the very long term the residual activity (and thermal power) decreases only slowly due to the long halflives of the dominant actinides. The activity after more that 1000 years is about 1 to 2 orders of magnitude lower than that of high-level waste, the low-level transuranium waste by a factor 10 to 4, respectively. The activity per unit volume of the packaged waste of the medium-level and actinide-containing wastes because of the bigger volume of the conditioned wastes is lower by 2 to 4 orders of magnitude up to about 500 years. After more than 1000 years the activities per unit volume are lower by a factor of 20 to 200 than that of high-level waste. (orig.)

  19. Nuclear level density: Shell-model approach

    Sen'kov, Roman; Zelevinsky, Vladimir

    2016-06-01

    Knowledge of the nuclear level density is necessary for understanding various reactions, including those in the stellar environment. Usually the combinatorics of a Fermi gas plus pairing is used for finding the level density. Recently a practical algorithm avoiding diagonalization of huge matrices was developed for calculating the density of many-body nuclear energy levels with certain quantum numbers for a full shell-model Hamiltonian. The underlying physics is that of quantum chaos and intrinsic thermalization in a closed system of interacting particles. We briefly explain this algorithm and, when possible, demonstrate the agreement of the results with those derived from exact diagonalization. The resulting level density is much smoother than that coming from conventional mean-field combinatorics. We study the role of various components of residual interactions in the process of thermalization, stressing the influence of incoherent collision-like processes. The shell-model results for the traditionally used parameters are also compared with standard phenomenological approaches.

  20. Collective enhancement in nuclear level densities

    Empirical estimations of the rotational and vibrational enhancement in the nuclear level density obtained from the analysis of the fragmentation cross sections for 238U projectile are discussed. (author)

  1. Actinide environmental chemistry

    In order to predict release and transport rates, as well as design cleanup and containment methods, it is essential to understand the chemical reactions and forms of the actinides under aqueous environmental conditions. Four important processes that can occur with the actinide cations are: precipitation, complexation, sorption and colloid formation. Precipitation of a solid phase will limit the amount of actinide in solution near the solid phase and have a retarding effect on release and transport rates. Complexation increases the amount of actinide in solution and tends to increase release and migration rates. Actinides can sorb on to mineral or rock surfaces which tends to retard migration. Actinide ions can form or become associated with colloidal sized particles which can, depending on the nature of the colloid and the solution conditions, enhance or retard migration of the actinide. The degree to which these four processes progress is strongly dependent on the oxidation state of the actinide and tends to be similar for actinides in the same oxidation state. In order to obtain information on the speciation of actinides in solution, i.e., oxidation state, complexation form, dissolved or colloidal forms, the use of absorption spectroscopy has become a method of choice. The advent of the ultrasensitive, laser induced photothermal and fluorescence spectroscopies has made possible the detection and study of actinide ions at the parts per billion level. With the availability of third generation synchrotrons and the development of new fluorescence detectors, X-ray absorption spectroscopy (XAS) is becoming a powerful technique to study the speciation of actinides in the environment, particularly for reactions at the solid/solution interfaces. (orig.)

  2. Geochemistry of actinides. Application to the storage of high level radioactive wastes. Under the supervision of Mr Michel Treuil

    This collective research report first addresses the chemistry of actinides with a description of their atomic orbitals and the study of their behaviour in solution. The author addresses several aspects: historical overview on actinides, radioactivity, chemical reactions in aqueous solution, redox chemistry, speciation in solution with respect to water characteristics in deep storage conditions. The second part gathers several studies performed on a natural laboratory (the Oklo site in which nuclear reactions occurred about 2 billions years ago) and reports the modelling of radionuclide transfer within a geological system (the model is applied to the Oklo site). The third part addresses issues related to the nuclear fuel cycle, and the storage modes and materials envisaged and involved regarding the storage of high level radioactive wastes, notably in France

  3. Parity dependence of nuclear level densities

    High resolution proton resonance data have been examined for a possible parity dependence of nuclear level densities. Five spin-parity combinations--1/2+, 1/2-, 3/2-, 3/2+, and 5/2+--have been analyzed for three datasets--44Ca(p,p), 48Ti(p,p), and 56Fe(p,p). Much of the uncertainty in the level density arises from the determination of the fraction of levels that are not observed. The missing fraction of levels was determined by (a) the standard width analysis method that assumes a Porter-Thomas distribution for the reduced widths and (b) a recently developed method that analyzes the spacing distribution and assumes the Wigner distribution for the nearest-neighbor spacings. There are indications of parity dependence of the level densities for several of the spin-parity combinations

  4. Combinatorial nuclear level-density model

    A microscopic nuclear level-density model is presented. The model is a completely combinatorial (micro-canonical) model based on the folded-Yukawa single-particle potential and includes explicit treatment of pairing, rotational and vibrational states. The microscopic character of all states enables extraction of level-distribution functions with respect to pairing gaps, parity and angular momentum. The results of the model are compared to available experimental data: level spacings at neutron separation energy, data on total level-density functions from the Oslo method, cumulative level densities from low-lying discrete states, and data on parity ratios. Spherical and deformed nuclei follow basically different coupling schemes, and we focus on deformed nuclei

  5. Combinatorial nuclear level-density model

    Uhrenholt, H. [Mathematical Physics, Lund University, P.O. Box 118, S-221 00 Lund (Sweden); Åberg, S., E-mail: sven.aberg@matfys.lth.se [Mathematical Physics, Lund University, P.O. Box 118, S-221 00 Lund (Sweden); Dobrowolski, A. [Institut Fizyki, UMCS Lublin, ul. Radziszewskiego 10, 20-031 Lublin (Poland); Døssing, Th. [Niels Bohr Institute, Blegdamsvej 17, Copenhagen (Denmark); Ichikawa, T. [Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502 (Japan); Möller, P. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2013-09-02

    A microscopic nuclear level-density model is presented. The model is a completely combinatorial (micro-canonical) model based on the folded-Yukawa single-particle potential and includes explicit treatment of pairing, rotational and vibrational states. The microscopic character of all states enables extraction of level-distribution functions with respect to pairing gaps, parity and angular momentum. The results of the model are compared to available experimental data: level spacings at neutron separation energy, data on total level-density functions from the Oslo method, cumulative level densities from low-lying discrete states, and data on parity ratios. Spherical and deformed nuclei follow basically different coupling schemes, and we focus on deformed nuclei.

  6. Spectral properties of actinide materials: Charge density self-consistent LDA+Hubbard I method in FP-LAPW basis

    We provide a numerically efficient procedure to perform LDA+Hubbard I calculations including self-consistency over the charge density in the FP-LAPW basis. The method is applied to Pu, Am, and PuAm and PuCe alloys. Our results for valence photoemission spectra (PES) agree with experimental data and with previous LDA+DMFT calculations. Analysis of the J=5/2 and J=7/2 contributions to the f-occupation supports the intermediate-coupling picture of f-states in heavy actinides. The electronic specific heat coefficient is calculated for PuAm and PuCe alloys in reasonable agreement with recent experiments. We show that Pu atoms keep their mixed-valence character in these alloys. Next, we study electronic and spectral properties of Pu-based superconductor PuCoGa5 and obtain good agreement with experimental PES. Finally, we analyze surface effects. In Pu monolayer, we find substantial modification of PES due to 5f-electron localization consistent with experimental observations.

  7. Contribution of the ''simple solutions'' concept to estimate density of actinides concentrated solutions

    In order to calculate criticality parameters of nuclear fuel solution systems, number density of nuclides are needed and they are generally estimated from density equations. Most of the relations allowing the calculation of the density of aqueous solutions containing the electrolytes HNO3-UO2(NO3)2-Pu(NO3)4, usually called 'nitrate dilution laws' are strictly empirical. They are obtained from a fit of assumed polynomial expressions on experimental density data. Out of their interpolation range, such mathematical expressions show discrepancies between calculated and experimental data appearing in the high concentrations range. In this study, a physico-chemical approach based on the isopiestic mixtures rule is suggested. The behaviour followed by these mixtures was first observed in 1936 by Zdanovskii and expressed as: 'Binary solutions (i.e. one electrolyte in water) having a same water activity are mixed without variation of this water activity value'. With regards to this behaviour, a set of basic thermodynamic expressions has been pointed out by Ryazanov and Vdovenko in 1965 concerning enthalpy, entropy, volume of mixtures, activity and osmotic coefficient of the components. In particular, a very simple relation for the density is obtained from the volume mixture expression depending on only two physico-chemical variables: i) concentration of each component in the mixture and in their respectively binary solutions having the same water activity as the mixture and ii), density of each component respectively in the binary solution having the same water activity as the mixture. Therefore, the calculation needs the knowledge of binary data (water activity, density and concentration) of each component at the same temperature as the mixture. Such experimental data are largely published in the literature and are available for nitric acid and uranyl nitrate. Nevertheless, nitric acid binary data show large discrepancies between the authors and need to be revised. In the

  8. DENSITY-FUNCTIONAL STUDY OF Zr-BASED ACTINIDE ALLOYS: 2. U-Pu-Zr SYSTEM

    Landa, A; Soderlind, P; Turchi, P; Vitos, L; Ruban, A

    2009-02-09

    Density-functional theory, previously used to describe phase equilibria in the U-Zr alloys [1], is applied to study ground state properties of the bcc U-Pu-Zr solid solutions. Calculated heats of formation of the Pu-U and Pu-Zr alloys are in a good agreement with CALPHAD assessments. We found that account for spin-orbit coupling is important for successful description of Pu-containing alloys.

  9. Computational Study of Covalency and Complexation in Actinides using Static and Dynamic Simulation and Topological Density Analysis

    Kirker, I. D. J.

    2013-01-01

    The separation of minor actinides such as americium and curium from other actinide and lanthanide-bearing components of used nuclear fuel is a necessary part of post-processing and recycling this fuel into storable components and new fuel material. Separation ratios can be optimised using a comprehensive understanding of the differences between these elements and their aqueous chemistry. This work uses computational simulation to investigate bonding behaviour and covalency differences between...

  10. Statistical nuclear properties (level densities, spin distributions)

    A general overview is given on the phenomenological methods used to describe the level densities in nuclei. Two well-known two-parameter formulas of level densities, the Back-Shifted Fermi Gas (BSFG) model and the Constant Temperature (CT) model, were used. A common ingredient of both is the spin distribution function, which contains in Ericsons's parametrization the spin-cutoff parameter σ. A realistic description of the parameters of both spin distribution function and the two level density models has been obtained by fitting the experimental data of 310 nuclei between 18F and 251Cf, consisting of the complete level schemes at low excitation energies and the s-wave neutron resonance spacings at the neutron binding energy. We determine a simple formula for the spin-cutoff parameter as a function of mass number and excitation energy. Also, an even-odd spin staggering in the spin distribution of the even-even nuclei was observed, and described with a simple formula. Using this newly defined spin distribution function, an empirical set of parameters of the BSFG and CT models was determined by fitting both the low-energy levels and the neutron resonance spacings. For these parameters, simple formulas were proposed that involve only quantities available from the mass tables, and allow reasonable estimations of the level density parameters for nuclei far from stability. Both the BSFG and CT models describe equally well the level densities at energies up to at least the neutron binding energy. Finally, we discuss recent experimental evidence that the CT model is the more correct description of the nuclei in the low-excitation energy (pairing) regime.

  11. Level density parameters for Fermi gas model

    Zhuang Youxiang; Wang Cuilan; Zhou Chunmei; Su Zongdi

    1986-08-01

    Nuclear level densities are crucial ingredient in the statistical models, for instance, in the calculations of the widths, cross sections, emitted particle spectra, etc. for various reaction channels. In this work 667 sets of more reliable and new experimental data are adopted, which include average level spacing D/sub 0/, radiative capture width GAMMA/sup 0//sub ..gamma../ at neutron binding energy and cumulative level number N/sub 0/ at the low excitation energy. They are published during 1973 to 1983. Based on the parameters given by Gilberg--Cameron and Cook the physical quantities mentioned above are calculated. The calculated results have the deviation obviously from experimental values. In order to improve the fitting, the parameters in the G--C formula are adjusted and a new set of level density parameters is obtained. The parameters in this work are more suitable to fit new measurements.

  12. Solubility and speciation of actinides in salt solutions and migration experiments of intermediate level waste in salt formations

    A comprehensive study into the solubility of the actinides americium and plutonium in concentrated salt solutions, the release of radionuclides from various forms of conditioned ILW and the migration behaviour of these nuclides through geological material specific to the Gorleben site in Lower Saxony is described. A detailed investigation into the characterization of four highly concentrated salt solutions in terms of their pH, Eh, inorganic carbon contents and their densities is given and a series of experiments investigating the solubility of standard americium(III) and plutonium(IV) hydroxides in these solutions is described. Transuranic mobility studies for solutions derived from the standard hydroxides through salt and sand have shown the presence of at least two types of species present of widely differing mobility; one migrating with approximately the same velocity as the solvent front and the other strongly retarded. Actinide mobility data are presented and discussed for leachates derived from the simulated ILW in cement and data are also presented for the migration of the fission products in leachates derived from real waste solidified in cement and bitumen. Relatively high plutonium mobilities were observed in the case of the former and in the case of the real waste leachates, cesium was found to be the least retarded. The sorption of ruthenium was found to be largely associated with the insoluble residues of the natural rock salt rather than the halite itself. (orig./RB)

  13. The effects of actinide separation on the radiological consequences of disposal of high-level radioactive waste on the ocean bed

    One option in the management of high-level radioactive wastes is to separate the actinides prior to vitrification and disposal. This option is examined in the context of disposal of high-level wastes on the deep ocean bed. The initial quantity of waste corresponds to the generation of 1000 GW(e)y of nuclear energy, and the actinide-separation process is assumed to remove 99% of all elements of atomic number greater than that of actinium. The models used to describe the dispersion of activity from a single disposal site on the bed of the Atlantic Ocean represent both local dispersion and long-term mixing. Collective doses and doses to individuals are calculated for six potential pathways: ingestion of fish, crustacea, molluscs, plankton and seaweed, and external irradiation from contaminated beach sediments. The period from 400 to 1,000,000 years after disposal is considered. The potential radiological impact from disposal of high-level waste without separation of actinides on the ocean bed arises from the actinides; isotopes of americium, neptunium and plutonium give the highest doses. Actinide separation would reduce these doses in proportion to the effectiveness of the separation process, until doses become determined by fission products rather than actinides: the achievable dose reduction would be a factor of approximately a hundred, or less for certain pathways. This reduction applies only to doses to the public from waste disposal: no account was taken of doses arising from the separation process itself or from the management of the separated actinides. The results of the assessment are contrasted with those of similar studies based on toxicity indices. Major deficiencies are identified in the use of toxicity indices as a basis for decision-making. (author)

  14. Separation of actinides and long-lived fission products from high-level radioactive wastes (a review)

    The management of high-level radioactive wastes is facilitated, if long-lived and radiotoxic actinides and fission products are separated before the final disposal. Especially important is the separation of americium, curium, plutonium, neptunium, strontium, cesium and technetium. The separated nuclides can be deposited separately from the bulk of the high-level waste, but their transmutation to short-lived nuclides is a muchmore favourable option. This report reviews the chemistry of the separation of actinides and fission products from radioactive wastes. The composition, nature and conditioning of the wastes are described. The main attention is paid to the solvent extraction chemistry of the elements and to the application of solvent extraction in unit operations of potential partitioning processes. Also reviewed is the behaviour of the elements in the ion exchange chromatography, precipitation, electrolysis from aqueous solutions and melts, and the distribution between molten salts and metals. Flowsheets of selected partitioning processes are shown and general aspects of the waste partitioning are shortly discussed. (orig.)

  15. Studies on actinide partitioning of high level waste solutions by technical scale solid phase extraction

    The twin column concept is designed to enhance the field of application of front chromatography. Operating in that mode, we could demonstrate, that the concentration curve of the chromatographic column effluent is composed of two fractions, the wall and interior fraction, having each a breakthrough volume at CBT/Cfeed = 50 % for the interior fraction (VBT) and CBO/Cfeed = φP/φC for the wall fraction (VBO). The corresponding volume ratio amounts to π/(π+2) = 0.61. On this basis, we established a chromatographic array composed of feed tank - 1. column - detector - 2. column - product tank and loaded the 1. column, until 1.22 VBT of feed has been conveyed through the column set. Then, CBO has been reached in the 2. column effluent. We can, thus, control the process below the detection limits of commercially available monitors. We employed the concept, to investigate the long-term behaviour of extractants recommended for the HLW partitioning. We could demonstrate, that CMPO appears to be an adequate extractant for partitioning HLW solutions in an actinide/lanthanide fraction and a fission/corrosion product fraction. However, we could not confirm, that (C1-C6H4)2=PS2H is sufficiently stable to maintain the chemical properties required for an actinide/lanthanide fractionation. We used one column filling with 10 g CMPO to process in total 1001 feed, thus economizing our studies. (author)

  16. Leaching of actinides and technetium from simulated high-level waste glass

    Leach tests were conducted using a modified version of the IAEA procedure to study the behavior of glass waste-solution interactions. Release rates were determined for Tc, U, Np, Pu, Am, Cm, and Si in the following solutions: WIPP B salt brine, NaCl (287 g/l), NaCl (1.76 g/1), CaCl2 (1.66 g/l), NaHCO3 (2.52 g/l), and deionized water. The leach rates for all elements decreased an order of magnitude from their initial values during the first 20 to 30 days leaching time. The sodium bicarbonate solution produced the highest elemental release rates, while the saturated salt brine and deionized water in general gave the lowest release. Technetium has the highest initial release of all elements studied. The technetium release rates, however, decreased by over four orders of magnitude in 150 days of leaching time. In the prepared glass, technetium was phase separated, concentrating on internal pore surfaces. Neptunium, in all cases except CaCl2 solution, shows the highest actinide release rate. In general, curium and uranium have the lowest release rates. The range of actinide release rates is from 10-5 to 10-8 g/cm2/day. 25 figures, 7 tables

  17. Actinides-1981

    1981-09-01

    Abstracts of 134 papers which were presented at the Actinides-1981 conference are presented. Approximately half of these papers deal with electronic structure of the actinides. Others deal with solid state chemistry, nuclear physic, thermodynamic properties, solution chemistry, and applied chemistry.

  18. Actinides-1981

    Abstracts of 134 papers which were presented at the Actinides-1981 conference are presented. Approximately half of these papers deal with electronic structure of the actinides. Others deal with solid state chemistry, nuclear physic, thermodynamic properties, solution chemistry, and applied chemistry

  19. Actinide partitioning by TODGA hollow fiber supported liquid membrane: a cold test with simulated high level waste

    Transport behaviour of lanthanides from PHWR-Simulated High Level Waste (SHLW) was investigated using hollow fibre supported liquid membrane (HFSLM) containing 0.1M TODGA (N,N,N',N'-tetraoctyl diglycolamide) + 0.5M DHOA (N,N-dihexyl octanamide) as the carrier. The transport studies were conducted on 20 litres scale as a cold test with PHWR-SHLW. All the lanthanides could be quantitatively transported into the strip phase in 18hrs. None of the other elements were transported except small quantities of Sr and Mo. The system showed reasonably good stability studied up to 72 hrs of continuous operation. The results suggested the possible application of TODGA-HFSLM system for the recovery of minor actinides from high level wastes. (author)

  20. Thermal-hydraulics of actinide burner reactors

    As a part of conceptual study of actinide burner reactors, core thermal-hydraulic analyses were conducted for two types of reactor concepts, namely (1) sodium-cooled actinide alloy fuel reactor, and (2) helium-cooled particle-bed reactor, to examine the feasibility of high power-density cores for efficient transmutation of actinides within the maximum allowable temperature limits of fuel and cladding. In addition, calculations were made on cooling of actinide fuel assembly. (author)

  1. Optimization of parameters of alpha spectrometry with silicon detector for low level measurements of actinides in environmental samples

    Determination of actinides in environmental and biological samples is an important activity of radiation protection program at nuclear energy facilities. High resolution alpha spectrometry with passivated ion implanted Silicon detectors is widely used for the determination of actinides concentration. Low levels of activity concentrations in these samples often require long counting duration of a few days to obtain accurate and statistically significant data for further impact assessment. In alpha spectrometry, the chamber in which Si detector operated is a critical component and maintained at a desired vacuum for minimizing the alpha particle attenuation. Experimental evaluation of variations in energy resolution and tailing of alpha spectra was investigated under different chamber air pressures from about 6.7 Pa to more than 2700 Pa under the chamber hold mode and pump electrically switched off conditions. As part of validation, data collected on an IAEA inter-comparison exercise sample are presented under short and long counting durations with pump operating and switched off conditions respectively. It has been observed that the FWHM values do not significantly degrade, to impact the low and medium level concentration alpha spectra, for variations in vacuum chamber pressures from about 6.7 Pa to 2700 Pa. - Highlights: ► Several parameters relevant to low level alpha spectrometry have been investigated and appropriately optimized. ► The most important parameter has been the influence of chamber pressure on resolution when the chamber is in hold mode while the vacuum pump is electrically switched off for more than 40 h. ► Samples were counted for about 4 day for low levels of detection. Efficiency, tail length, detector size and other parameters were evaluated.

  2. Subsurface Biogeochemistry of Actinides

    Kersting, Annie B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Univ. Relations and Science Education; Zavarin, Mavrik [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Glenn T. Seaborg Inst.

    2016-06-29

    A major scientific challenge in environmental sciences is to identify the dominant processes controlling actinide transport in the environment. It is estimated that currently, over 2200 metric tons of plutonium (Pu) have been deposited in the subsurface worldwide, a number that increases yearly with additional spent nuclear fuel (Ewing et al., 2010). Plutonium has been shown to migrate on the scale of kilometers, giving way to a critical concern that the fundamental biogeochemical processes that control its behavior in the subsurface are not well understood (Kersting et al., 1999; Novikov et al., 2006; Santschi et al., 2002). Neptunium (Np) is less prevalent in the environment; however, it is predicted to be a significant long-term dose contributor in high-level nuclear waste. Our focus on Np chemistry in this Science Plan is intended to help formulate a better understanding of Pu redox transformations in the environment and clarify the differences between the two long-lived actinides. The research approach of our Science Plan combines (1) Fundamental Mechanistic Studies that identify and quantify biogeochemical processes that control actinide behavior in solution and on solids, (2) Field Integration Studies that investigate the transport characteristics of Pu and test our conceptual understanding of actinide transport, and (3) Actinide Research Capabilities that allow us to achieve the objectives of this Scientific Focus Area (SFA and provide new opportunities for advancing actinide environmental chemistry. These three Research Thrusts form the basis of our SFA Science Program (Figure 1).

  3. The many-body level density

    We investigate the many-body level density ρMB for fermion and boson gases. We establish its behavior as a function of the temperature and the number of particles. We deal with correction terms due to finite number of particles effects for ρMB: for fermions, it seems that it exists only one behavior. We propose a semiclassical expression of ρMB for two types of particles with an angular momentum. It is decomposed into a smooth part coming from the saddle point method plus corrective terms due to the expansion of the number of partitions for two types of particles and an oscillating part coming from the fluctuations of the single-particle level density. Our model is validated by a numerical study. For the case of the atomic nucleus, the oscillating part of ρMB is controlled by a temperature factor which depends on the chaotic or integrable nature of the system and on the fluctuation of the ground state energy. This leads to consider in more detail this last quantity. For an isolated system, we give the general expression of the mean value for fixed potentials. We treat the self-bound system case through the example of the three dimensional harmonic oscillator (3DHO). Furthermore we study the oscillating part of ρMB for bosons in the low temperature regime for billiards and for isotropic 3DHO. We note the oscillations disappear leading to a power law correction. In the case of the isotropic 3DHO, these corrections have the same order of magnitude as the smooth part. In the same way, for the high temperature regime we show the oscillating part of ρMB is exponentially negligible compared to the smooth part. (author)

  4. Decay calculations on medium-level and actinide-containing wastes from the LWR fuel cycle. Pt. 2

    1. The radiotoxicity index as inherent property of the radionuclide inventory was calculated for medium-level and actinide-containing wastes. The calculations were based on the annual limits of intake of the German Radiation Protection Ordinance as well as the new values of annual limits of intake from ICRP-30. The latter imply a higher rating of the toxicity of transuranium nuclides and a lower rating of Sr-90, Tc-99, and Ra-226. Thus, the annual radiotoxicity index is controlled by the transuranics after 10 to 100 years. 2. From the comparison of the radiotoxicity index of conditional and packed wastes with the same volume of uranium ore, it was evaluated that the relative radiotoxicity of the medium-level wastes decreases below the level of pitchblende after less than 100 years and below a 3% uranium ore after less than 2000 of decay. However, based on ICRP-30, the relative radiotoxicity index decreases below the level of pitchblende after 1000 years and decays to the level of the 3% uranium ore at about 105 years. 3. The comparison of the radiotoxicity concentration of the total disposal layer with a uranium ore deposit shows that the radiotoxicity concentration based on ICRP-30 of the self-heating wastes placed in single boreholes decays within 2000 years (high level waste within 3000 years) below the level of a uranium ore deposit of 0.2% uranium. The radiotoxicity concentration of the medium-level process waste and the alpha-waste disposed off in disposal chambers decreases to the level of a uranium ore deposit with 0.4 to 6% uranium after about 104 years, and 1% after about 105 years. (orig./HP)

  5. Management-retrieval system of the level density parameter library

    The level density parameter sub-library of Chinese evaluated nuclear parameter library (CENPL) contains eight sets of the level density parameters commonly used in the nuclear data evaluations and calculations, and some important experimental data related to the level density. The author presents an introduction to the management-retrieval system of the library

  6. Demonstration of modifier-free trivalent actinide partitioning from simulated high-level liquid waste using unsymmetrical diglycolamide

    Partitioning of trivalent lanthanides and actinides from fast-reactor (FR) simulated high-level liquid waste (SHLLW) has been demonstrated, for the first time, using a modifier-free unsymmetrical diglycolamide, N,N,-didodecyl-N',N'-dioctyl- 3-oxapentane-1,5-diamide (D3DODGA), in n-dodecane (n-DD). The extraction behavior of various metal ions present in the FR-SHLLW was studied using a solution of 0.1 M D3DODGA/n-DD. The extraction of Am(III) was accompanied by the co-extraction of all lanthanides and unwanted metal ions such as Zr(IV), Y(III), and Pd(II) from FR-SHLLW. The coextraction of unwanted metal ions was minimized by adding suitable aqueous soluble complexing agents. The stripping of Am(III) and Ln(III) from the loaded organic phase was studied using dilute nitric acid. Based on those results, a counter-current mixer-settler run was performed in a 20-stage mixer-settler. (author)

  7. Nuclear Level Density at High Spin and Excitation Energy

    A.N. Behkami; Z. Kargar

    2001-01-01

    The intensive studies of equilibrium processes in heavy-ion reaction have produced a need for information on nuclear level densities at high energies and spins. The Fermi gas level density is often used in investigation of heavy-ion reaction studies. Some papers have claimed that nuclear level densities might deviate substantially from the Fermi gas predications at excitations related to heavy-ion reactions. The formulae of calculation of the nuclear level density based on the theory of superconductivity are presented, special attention is paid to the dependence of the level density on the angular momentum. The spin-dependent nuclear level density is evaluated using the pairing interaction. The resulting level density for an average spin of 52h is evaluated for 155Er and compared with experimental data. Excellent agreement between experiment and theory is obtained.``

  8. Research on GSM level density formula and its parameters

    The Generalized Superfluid Model (GSM) level density formula has been studied. On the basis of the average neutron resonance level spacing D0 and cumulative level number N0 which were evaluated by ourselves, a set of GSM level density parameters has been obtained. These parameters have been included in the initial data file of IAEA's Reference Input Parameter Library (RIPL)

  9. Studies on the separation of minor actinides from high-level wastes by extraction chromatography using novel silica-based extraction resins

    Wei, Y.; Kumagai, M; Takashima, Y.; Modolo, G.; R. Odoj

    2000-01-01

    To develop an advanced partitioning process by extraction chromatography using a minimal organic solvent and compact equipment to separate minor actinides such as Am and Cm from nitrate acidic high-level waste (HLW) solution, several novel silica-based extraction resins have been prepared by impregnating organic extractants into the styrene-divinylbenzene copolymer, which is immobilized in porous silica particles (SiO2-P). The extractants include octyl(phenyl)-N, N-diisobutylcarbamoylmethylph...

  10. Adaptation of ICP-AES in lead cell facility in Chemistry Group, IGCAR and analysis of simulated high level waste as a part of the studies on minor actinide partitioning

    The spent fuel discharged from the nuclear reactor contains unused uranium and plutonium, and Np, Am, Cm called as minor actinides and fission products. Spent fuel is dissolved in nitric acid. U and Pu are recovered by a solvent extraction process known as PUREX process using 1.1 M TBP as extractant. The raffinate rejected is known as High Level Liquid Waste which is a complex mixture of minor actinides, corrosion products, and fission products. Partitioning of minor actinides (MA) and its transmutation is a viable strategy for the safe management of high level liquid waste (HLLW)

  11. New developments and methodology for actinide measurements at ultra trace levels using ICP-MS

    For safeguards purposes, there is a real need for accurate and reliable measurements of plutonium isotopes at the lowest level in environmental samples. It is of prime necessity to detect the ultra-trace levels with the best confidence in order to avoid any false positive or negative detection. To do this, an analytical methodology devoted to plutonium measurements at femtogram levels in environmental samples has been optimised. This methodology is based on the combination of an efficient radiochemistry and of a very sensitive ICP-MS detection. This work first identifies and quantifies the polyatomic interferences that occur at m/z = 239. Heavy elements like mercury can generate 199Hg40Ar+ at a rate ranging from 10-4 to 10-3. These interfering elements concentrations in purified solutions have been determined at trace (pg.ml-1) levels but their contributions need anyway to be corrected. Then, our method for determining plutonium detection limits on real samples is described. It is based on the combination of standard deviations over uranium hydride, abundance sensitivity, impurities from 242Pu isotopic dilution tracer corrections, and standard deviation over count rates of selected neighbouring (241-247) masses acquired during the measurements of the samples. The specific radiochemistry, devoted to ultra-trace measurements is presented. The different sources of contamination have been quantified. The crucial step for uranium elimination from purified solution has been identified to be the rinsing of anionic chromatography column with adequate volume of 8M HNO3. Micro-nebulisers can be used, down to 50μl.min-1 in operational conditions. Metrological settings of ICP-MS have to be optimised, especially dead time and mass bias correction. Finally we investigated the potentialities of the coupling of femtosecond laser ablation system and ICP-MS as an alternative to TIMS with respect to particle analysis. Preliminary results appear to be very promising because LA

  12. Increased indoor Rn levels due to actinide containing mineral collections displayed in living areas

    Collection of crystals ranging from quartz to U or Th containing minerals is a widespread spare time activity in Switzerland. Radon emanation from stones displayed in showcases in the living area may contribute considerably to elevated Rn levels in the indoor air. Time-averaged Rn gas measurements in 35 homes of subscribers to a journal for mineral collectors showed an unexpected statistically significant increase of 98 Bq m-3 in the Rn level of the room containing the collections compared to the levels measured in a control room on the same floor. Using ICRP Publication 50 conversion factors for indoor exposure to Rn decay products, the additional effective dose equivalent contracted was estimated to amount to an average of 2.7 mSv y-1. Although the 220Rn emanation rate, as measured in the display cases, was considerable in several cases, the dose from 220Rn decay products in the living area remained always a small fraction of the Rn dose. Remedial actions for crystal collections containing considerable amounts of U- or Th-based minerals are suggested

  13. Rotational modes contribution to the observed level density

    Attempt is made to apply the level density systematics within the framework of the generalized superfluid model to the A<150 region. The analysis of some properties of these nuclei (e.g. deformation energy, neutron resonance density, neutron evaporation spectra) shows the existence of large groups of nuclei, for which the contribution of rotational modes to their level density is considerable (in spite of the traditional classification according to low-lying discrete level spectra). (author)

  14. New developments and methodology for actinide measurements at ultra trace levels

    Full text: The methodology developed in our laboratory is based on the combination of radiochemistry conducted in the cleanest laboratories, prior to measurements using mass spectrometers with detection limits in the sub femtogram range. The work describes first the different radiochemical procedures that are needed to completely purify a sample. When femtogram levels of 239Pu or 240Pu have to be measured, the matrix and uranium have to be completely removed. First to avoid the interferences generated on 239Pu by uranium hydrides i.e. 238UH and secondly to avoid the interferences of polyatomics generated by lead, bismuth, mercury...The contribution of 199Hg40Ar, 204Hg35Cl or 202Hg37Cl on 239Pu have been quantified and it is close to 10-6. Consequently, the radiochemistry, mainly based on anionic chromatography performed using ultra-pure reagents at crucial steps is detailed, leading to blanks with no more than ppt levels of 238U, lead, bismuth and mercury. Then, the way to improve the performance of mass spectrometers, ICP-MS and TIMS is described. Very low ICP-MS detection limits are a combination of very high sensitivity, low backgrounds and very low sample consumption. Low consumption is achieved by using micro nebulisers with a flow rate which doesn't exceed 50μl.min-1 without decreasing sensitivity. Enhancement of sensitivity with micro nebulisers is then possible by using desolvating systems that completely remove water from the sample, resulting in an increase in sensitivity by a factor of ten. Better performance of ICP-MS is also achievable when a collision cell is added, in order to decrease uranium hydrides and other polyatomics. Concerning TIMS, which generally suffers from a lack in sensitivity, total consumption of sample was studied in order to get better detection limits with respect to uranium isotopes and specifically 236U. The performance of TIMS and ICP-MS in terms of detection limits, precision, reliability, mass bias and isotopic fractionation

  15. Electronic structure and core-level spectra of light actinide dioxides in the dynamical mean-field theory

    Kolorenč, Jindřich; Shick, Alexander; Lichtenstein, A.I.

    2015-01-01

    Roč. 92, č. 8 (2015), "085125-1"-"085125-10". ISSN 1098-0121 R&D Projects: GA ČR GC15-05872J Institutional support: RVO:68378271 Keywords : electronic-structure calculations * dynamical mean-field theory * Mott insulators * actinides * oxides * photoemission Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.736, year: 2014

  16. Research on the chemical speciation of actinides

    A demand for the safe and effective management of spent nuclear fuel and radioactive waste generated from nuclear power plant draws increasing attention with the growth of nuclear power industry. The objective of this project is to establish the basis of research on the actinide chemistry by using advanced laser-based highly sensitive spectroscopic systems. Researches on the chemical speciation of actinides are prerequisite for the development of technologies related to nuclear fuel cycles, especially, such as the safe management of high level radioactive wastes and the chemical examination of irradiated nuclear fuels. For supporting these technologies, laser-based spectroscopies have been performed for the chemical speciation of actinide in an aqueous solutions and the quantitative analysis of actinide isotopes in spent nuclear fuels. In this report, results on the following subjects have been summarized. (1) Development of TRLFS technology for chemical speciation of actinides, (2) Development of LIBD technology for measuring solubility of actinides, (3) Chemical speciation of plutonium complexes by using a LWCC system, (4) Development of LIBS technology for the quantitative analysis of actinides, (5) Development of technology for the chemical speciation of actinides by CE, (6) Evaluation on the chemical reactions between actinides and humic substances, (7) Chemical speciation of actinides adsorbed on metal oxides surfaces, (8) Determination of actinide source terms of spent nuclear fuel

  17. Limits of thermodynamic models for nuclear level densities

    The current status of thermodynamic models as applied to nuclear level densities is reviewed. Considerable refinement has taken place during the last fifteen years, with the result that some of the undesirable assumptions originally required by the model are no longer necessary. Some problems remain, however, particularly in calculating level densities for deformed nuclei. Furthermore, some related parameters, such as the positive-parity negative-parity ratio for levels and the spin cutoff parameter are more sensitive to the presence of two-body interactions than the total level density. Improvement in characterization of nuclear level densities will require use of techniques which can incorporate the effects of two-body interactions in the level density calculation. 25 references

  18. Actinide recovery techniques utilizing electromechanical processes

    Under certain conditions, the separation of actinides using electromechanical techniques may be an effective means of residue processing. The separation of granular mixtures of actinides and other materials discussed in this report is based on appreciable differences in the magnetic and electrical properties of the actinide elements. In addition, the high density of actinides, particularly uranium and plutonium, may render a simultaneous separation based on mutually complementary parameters. Both high intensity magnetic separation and electrostatic separation have been investigated for the concentration of an actinide waste stream. Waste stream constituents include an actinide metal alloy and broken quartz shards. The investigation of these techniques is in support of the Integral Fast Reactor (IFR) concept currently being developed at Argonne National Laboratory under the auspices of the Department of Energy

  19. Actinide production in 136Xe bombardments of 249Cf

    The production cross sections for the actinide products from 136Xe bombardments of 249Cf at energies 1.02, 1.09, and 1.16 times the Coulomb barrier were determined. Fractions of the individual actinide elements were chemically separated from recoil catcher foils. The production cross sections of the actinide products were determined by measuring the radiations emitted from the nuclides within the chemical fractions. The chemical separation techniques used in this work are described in detail, and a description of the data analysis procedure is included. The actinide production cross section distributions from these 136Xe + 249Cf bombardments are compared with the production cross section distributions from other heavy ion bombardments of actinide targets, with emphasis on the comparison with the 136Xe + 248Cm reaction. A technique for modeling the final actinide cross section distributions has been developed and is presented. In this model, the initial (before deexcitation) cross section distribution with respect to the separation energy of a dinuclear complex and with respect to the Z of the target-like fragment is given by an empirical procedure. It is then assumed that the N/Z equilibration in the dinuclear complex occurs by the transfer of neutrons between the two participants in the dinuclear complex. The neutrons and the excitation energy are statistically distributed between the two fragments using a simple Fermi gas level density formalism. The resulting target-like fragment initial cross section distribution with respect to Z, N, and excitation energy is then allowed to deexcite by emission of neutrons in competition with fission. The result is a final cross section distribution with respect to Z and N for the actinide products. 68 refs., 33 figs., 6 tabs

  20. Ultra-low level (pg/L) actinide determinations and superior isotope ratio precisions by quadrupole ICP-MS

    A very high sensitivity, quadrupole-based inductively coupled plasma mass spectrometer (ICP-MS) has been developed and employed to measure very low concentrations (pg/L) of various actinides in solution. The detection capabilities of the instrument are shown using a variety of sample introduction methods, including simple direct sample nebulization, higher efficiency sample nebulization, and column preconcentration. This allowed three sigma detection limits in the range from 33 to 0.07 pg/L to be achieved, using short integration times, for a number of actinides. In addition, the improved sensitivity allowed isotope ratio measurements to be undertaken with good precision, (0.05 to 0.2%) at low concentrations (0.5 to 5 microg/L), without requiring long acquisition times. The results of isotope ratio measurements on silver, lead, and NIST natural lead standard SRM 981 will be reported

  1. Systematic study of neutron induced reactions of the actinide nuclei

    Maslov, V.M. [Akadehmiya Navuk Belarusi, Minsk (Belarus). Inst. Radyyatsyjnykh Fizika-Khimichnykh Prablem; Kikuchi, Yasuyuki

    1996-06-01

    A statistical theory is used for the calculation of the neutron-induced reaction cross sections of actinide nuclides from 10 keV up to 20 MeV. Available experimental data bases for major actinides were extensively used to develop theoretical tools for consistent evaluation of neutron data of minor actinides. The approach employed up to the second chance fission threshold is based on the full-scale Hauser-Feshbach theory, a phenomenological modelling of level densities, the giant dipole resonance model for gamma-ray emission, the double-humped fission barrier model and the coupled channel optical model calculations. The pairing, collective and shell effects are introduced into the level density model for equilibrium and saddle point deformations. Step-like structures observed in fission cross section of {sup 235}U around 1 MeV incident neutron energies are interpreted as due to pairing effects. Pairing correlation parameters are adjusted to fit the fission cross section slope in the first plateau region. The level density collective effect inclusion influences drastically the extracted experimental fission barrier parameters due to the inner saddle point asymmetry. The shell effects dumping is manifested as a consistent fit of fission data above the second chance fission threshold. In case of minor actinides, fission data fits are used as a constraint for capture and inelastic scattering cross section predictions. The capture cross sections were analyzed with the allowance for (n,{gamma}n`) and (n,{gamma}f) reactions. To fit the high-energy tails in the (n,2n) reaction, the pre-equilibrium processes in the neutron channel were included. All these effects were modelled, and the model parameters were obtained using major actinides neutron data. The resulted parameter systematics were applied for analysis of available data and prediction of capture, inelastic scattering, (n,2n), (n,3n) reaction and fission cross sections. (J.P.N.). 87 refs.

  2. Actinides recycling assessment in a thermal reactor

    Highlights: • Actinides recycling is assessed using BWR fuel assemblies. • Four fuel rods are substituted by minor actinides rods in a UO2 and in a MOX fuel assembly. • Performance of standard fuel assemblies and the ones with the substitution is compared. • Reduction of actinides is measured for the fuel assemblies containing minor actinides rods. • Thermal reactors can be used for actinides recycling. - Abstract: Actinides recycling have the potential to reduce the geological repository burden of the high-level radioactive waste that is produced in a nuclear power reactor. The core of a standard light water reactor is composed only by fuel assemblies and there are no specific positions to allocate any actinides blanket, in this assessment it is proposed to replace several fuel rods by actinides blankets inside some of the reactor core fuel assemblies. In the first part of this study, a single uranium standard fuel assembly is modeled and the amount of actinides generated during irradiation is quantified for use it as reference. Later, in the same fuel assembly four rods containing 6 w/o of minor actinides and using depleted uranium as matrix were replaced and depletion was simulated to obtain the net reduction of minor actinides. Other calculations were performed using MOX fuel lattices instead of uranium standard fuel to find out how much reduction is possible to obtain. Results show that a reduction of minor actinides is possible using thermal reactors and a higher reduction is obtained when the minor actinides are embedded in uranium fuel assemblies instead of MOX fuel assemblies

  3. Recovering actinide values

    Actinide values are recovered from sodium carbonate scrub waste solutions containing these and other values along with organic compounds resulting from the radiolytic and hydrolytic degradation of neutral organophosphorus extractants such as tri-n butyl phosphate (TBP) and dihexyl-N, N-diethyl carbamylmethylene phosphonate (DHDECMP) which have been used in the reprocessing of irradiated nuclear reactor fuels. The scrub waste solution is made acidic with mineral acid, to form a feed solution which is then contacted with a water-immiscible, highly polar organic extractant which selectively extracts the degradation products from the feed solution. The feed solution can then be processed to recover the actinides for storage or recycled back into the high-level waste process stream. The extractant can be recycled after stripping the degradation products with a neutral sodium carbonate solution. (author)

  4. Nuclear Level Density: Shell Model vs Mean Field

    Sen'kov, Roman

    2015-01-01

    The knowledge of the nuclear level density is necessary for understanding various reactions including those in the stellar environment. Usually the combinatorics of Fermi-gas plus pairing is used for finding the level density. Recently a practical algorithm avoiding diagonalization of huge matrices was developed for calculating the density of many-body nuclear energy levels with certain quantum numbers for a full shell-model Hamiltonian. The underlying physics is that of quantum chaos and intrinsic thermalization in a closed system of interacting particles. We briefly explain this algorithm and, when possible, demonstrate the agreement of the results with those derived from exact diagonalization. The resulting level density is much smoother than that coming from the conventional mean-field combinatorics. We study the role of various components of residual interactions in the process of thermalization, stressing the influence of incoherent collision-like processes. The shell-model results for the traditionally...

  5. Nuclear shape transitions, level density, and underlying interactions

    Karampagia, S

    2016-01-01

    The configuration interaction approach to nuclear structure uses the effective Hamiltonian in a finite orbital space. The various parts of this Hamiltonian and their interplay are responsible for specific features of physics including the shape of the mean field and level density. This interrelation is not sufficiently understood. We intend to study phase transitions between spherical and deformed shapes driven by different parts of the nuclear Hamiltonian and to establish the presence of the collective enhancement of the nuclear level density by varying the shell-model matrix elements. Varying the interaction matrix elements we define, for nuclei in the sd and pf shells, the sectors with spherical and deformed shapes. Using the moments method that does not require the full diagonalization we relate the shape transitions with the corresponding level density. Enhancement of the level density in the low-energy part of the spectrum is observed in clear correlation with a deformation phase transition induced main...

  6. Actinide Waste Forms and Radiation Effects

    Ewing, R. C.; Weber, W. J.

    Over the past few decades, many studies of actinides in glasses and ceramics have been conducted that have contributed substantially to the increased understanding of actinide incorporation in solids and radiation effects due to actinide decay. These studies have included fundamental research on actinides in solids and applied research and development related to the immobilization of the high level wastes (HLW) from commercial nuclear power plants and processing of nuclear weapons materials, environmental restoration in the nuclear weapons complex, and the immobilization of weapons-grade plutonium as a result of disarmament activities. Thus, the immobilization of actinides has become a pressing issue for the twenty-first century (Ewing, 1999), and plutonium immobilization, in particular, has received considerable attention in the USA (Muller et al., 2002; Muller and Weber, 2001). The investigation of actinides and

  7. Combinatorial nuclear level density by a Monte Carlo method

    Cerf, N.

    1993-01-01

    We present a new combinatorial method for the calculation of the nuclear level density. It is based on a Monte Carlo technique, in order to avoid a direct counting procedure which is generally impracticable for high-A nuclei. The Monte Carlo simulation, making use of the Metropolis sampling scheme, allows a computationally fast estimate of the level density for many fermion systems in large shell model spaces. We emphasize the advantages of this Monte Carlo approach, particularly concerning t...

  8. Pairing effect on nuclear level density parameters in 116Sn

    Pairing correlations have a special importance for many fermion systems. Pairing correlations have been successfully described by the Bardeen-Cooper-Schrieffer (BCS) theory of superconductivity. In this work, the pairing gap parameters as a function of nuclear temperature for 116Sn have been evaluated. Then the nuclear level density and entropy have been determined using BCS Hamiltonian with inclusion of pairing effects. Also temperature dependence of level density parameters has been investigated.

  9. Parity dependence of level densities in 49V

    In this research, we have studied 48Ti(p, p1) and 48(p, p1γ) in an effort to determine the dependence of level densities on parity in the compound nucleus 49V. This nuclide was chosen because of the high level density of the 49V system (leading to good statistical accuracy) and because the target is zero spin (making the assignment of J easier). 5 refs., 3 figs

  10. PWRs potentialities for minor actinides burning

    In the frame of the SPIN program at CEA, the impacts of the minor actinides (MA) incineration in PWRs are analysed. The aim is to reduce the mass, the potential radiotoxicity level. The recycling of all actinide elements is evaluated in a PWR nuclear yard. A sensitivity study is done to evaluate the incineration for each minor actinide element. This gives the most efficient way of incineration for each MA elements in a PWR and helps to design a PWR burner. This burner is disposed in a PWR nuclear system in which the actinides are recycled until equilibrium. (author)

  11. Unified model of nuclear mass and level density formulas

    The objective of present work is to obtain a unified description of nuclear shell, pairing and deformation effects for both ground state masses and level densities, and to find a new set of parameter systematics for both the mass and the level density formulas on the basis of a model for new single-particle state densities. In this model, an analytical expression is adopted for the anisotropic harmonic oscillator spectra, but the shell-pairing correlation are introduced in a new way. (author)

  12. Unified model of nuclear mass and level density formulas

    Nakamura, Hisashi

    2001-03-01

    The objective of present work is to obtain a unified description of nuclear shell, pairing and deformation effects for both ground state masses and level densities, and to find a new set of parameter systematics for both the mass and the level density formulas on the basis of a model for new single-particle state densities. In this model, an analytical expression is adopted for the anisotropic harmonic oscillator spectra, but the shell-pairing correlation are introduced in a new way. (author)

  13. Applications of inductively coupled plasma-mass spectrometry to the determination of actinides and fission products in high level radioactive wastes at the Savannah River Site

    Four years of experience in applying inductively coupled plasma-mass spectrometry (ICP-MS) to the analysis of actinides and fission products in high level waste (HLW) samples at the Savannah River Site has led to the development of a number of techniques to aid in the interpretation of the mass spectral data. The goal has been to develop rapid and reliable analytical procedures that provide the necessary chemical and isotopic information to answer the process needs of the customers. Techniques that have been developed include the writing of computer software to strip the experimental data from the instrumental data files into spreadsheets or into a spectral data processing package so that the raw mass spectra can be overlain for comparison or plotted with higher output resolution. These procedures have been applied to problems ranging from the analysis of the high level waste tanks to reactor moderator water as well as environmental samples. Criticality safety analyses in some HLW waste treatment processes depend upon actinide concentration and isotopic information generated by ICP-MS, particularly in tanks with high concentrations of 137Cs and 90Sr. Experimental results for a number of these applications will be presented. These procedures represent a considerable saving in time and expense as compared to conventional chemical separation followed by radiochemical analyses, as well as decreased radiation exposure for the analysts

  14. Semi-empirical nuclear level density formula with shell effects

    A semi-empirical nuclear level density formula is proposed, which takes into account the influence of nuclear shell structure on level densities and the excitation energy dependence of shell effects. The ground state shell and pairing energies enter directly into this formula, which involves three mass-independent parameters characterizing the average single-particle level density near the Fermi level and the wave length of shell oscillations. The present formulation is shown not only to give a good fit to the experimental data on neutron resonance spacings of spherical nuclei, but also provide a reliable extrapolation to higher excitation energies. The present analysis has also brought out the need to include the dependence of level density parameter 'a(underlined)' on the surface to volume ratio of nuclei. The analysis of the data for deformed nuclei with the present formulation does not indicate an enhancement of the level densities of the magnitude suggestive of a rotation degree of freedom completely decoupled from intrinsic degrees at the excitation energy equal to neutron binding energies. (author)

  15. Level density of radioactive doubly-magic nucleus 56Ni

    In this work the single particle energies are obtained by diagonalising the Nilsson Hamiltonian in the cylindrical basis and are generated up to N =11 shells for the isotopes of Ni from A = 48-70, emphasizing the three magic nuclei viz, 48Ni, 56Ni and 68Ni. The statistical quantities like excitation energy, level density parameter and nuclear level density which play the important roles in the nuclear structure and nuclear reactions can be calculated theoretically by means of the Statistical or Partition function method. Hence the statistical model approach is followed to probe the dynamical properties of the nucleus in the microscopic level

  16. Research on the chemical speciation of actinides

    A demand for the safe and effective management of spent nuclear fuel and radioactive waste generated from nuclear power plant draws increasing attention with the growth of nuclear power industry. The objective of this project is to establish the basis of research on the actinide chemistry by using highly sensitive and advanced laser-based spectroscopic systems. Researches on the chemical speciation of actinides are prerequisite for the development of technologies related to nuclear fuel cycles, especially, such as the safe management of high level radioactive wastes and the chemical examination of irradiated nuclear fuels. For supporting these technologies, laser-based spectroscopies have been applied for the chemical speciation of actinide in aqueous solutions and the quantitative analysis of actinide isotopes in spent nuclear fuels. In this report, results on the following subjects have been summarized. Development of TRLFS technology for the chemical speciation of actinides, Development of laser-induced photo-acoustic spectroscopy (LPAS) system, Application of LIBD technology to investigate dynamic behaviors of actinides dissolution reactions, Development of nanoparticle analysis technology in groundwater using LIBD, Chemical speciation of plutonium complexes by using a LWCC system, Development of LIBS technology for the quantitative analysis of actinides, Evaluation on the chemical reactions between actinides and humic substances, Spectroscopic speciation of uranium-ligand complexes in aqueous solution, Chemical speciation of actinides adsorbed on metal oxides surfaces

  17. Road Density and Levels of Development in West Bengal

    Shamshad; Dr. Jabir Hasan Khan

    2012-01-01

    The present paper is an attempt to analyse the spatial patterns of road density, variations in the level of development and casual relationship between road density (dependent variable) and selected variables of socio-economic development (independent variables) among the districts of the state of West Bengal. The entire research work is based on secondary sources of data, collected from Census of India publications (2001), New Delhi and Bureau of Applied Economics and Statistics, West Bengal...

  18. Development of Todga extraction process for high-level liquid waste preliminary evaluation of actinide separation by calculation

    Extraction process for actinide separation from HLLW with N,N,N',N'-tetra-octyl-3-oxa-pentane-diamide (TODGA) was preliminarily evaluated by calculation of Am and Sr behaviors. Results of the calculation showed that it is possible to establish an extraction process with 0.1 M or 0.2 M TODGA in n-dodecane, where Am is extracted in a very high yield of more than 99.99% and Sr is kept in the aqueous phase in a yield of more than 99.95%. The solution volume required for the treatment of an unit amount of HLLW was also evaluated using data on extraction capacity as the first step for the estimation of the process scale. (author)

  19. Application of the triaxial quadrupole-octupole rotor to the ground and negative-parity levels of actinide nuclei

    Nadirbekov, M. S.; Minkov, N.; Strecker, M.; Scheid, W.

    2016-03-01

    In this work, we examine the possibility to describe yrast positive- and negative-parity excitations of deformed even-even nuclei through a collective rotation model in which the nuclear surface is characterized by triaxial quadrupole and octupole deformations. The nuclear moments of inertia are expressed as sums of quadrupole and octupole parts. By assuming an adiabatic separation of rotation and vibration degrees of freedom, we suppose that the structure of the positive- and negative-parity bands may be determined by the triaxial-rigid-rotor motion of the nucleus. By diagonalizing the Hamiltonian in a symmetrized rotor basis with embedded parity, we obtain a model description for the yrast positive- and negative-parity bands in several actinide nuclei. We show that the energy displacement between the opposite-parity sequences can be explained as the result of the quadrupole-octupole triaxiality.

  20. Application of the triaxial quadrupole-octupole rotor to the ground and negative-parity levels of actinide nuclei

    Nadirbekov, M S; Strecker, M; Scheid, W

    2016-01-01

    In this work we examine the possibility to describe yrast positive- and negative-parity excitations of deformed even-even nuclei through a collective rotation model in which the nuclear surface is characterized by triaxial quadrupole and octupole deformations. The nuclear moments of inertia are expressed as sums of quadrupole and octupole parts. By assuming an adiabatic separation of rotation and vibration degrees of freedom we suppose that the structure of the positive- and negative- parity bands may be determined by the triaxial-rigid-rotor motion of the nucleus. By diagonalizing the Hamiltonian in a symmetrized rotor basis with embedded parity we obtain a model description for the yrast positive- and negative-parity bands in several actinide nuclei. We show that the energy displacement between the opposite-parity sequences can be explained as the result of the quadrupole-octupole triaxiality.

  1. Signature of collective enhancement in nuclear level density

    In nuclei, coupling of collective rotation and vibration with the single particle excitations causes an enhancement in the level density. For nuclei with appreciable ground state deformation, most significant contribution to the collective enhancement comes from the rotational excitations, whereas in case of spherical nuclei, the collective enhancement is likely to be due to vibrational excitations. In this paper to independently verify the status of collective enhancement, a new experiment is reported where 169Tm, 185Re, and 201Tl compound nuclei having widely different ground state deformations have been populated. The experiment was done at two energies to observe the variation, if any, of the level density parameter with energy

  2. Nuclear level density formula with shell-pairing correlation terms

    The systematics of parameters for the level density formula based on the SPC model is studied by using the neutron and the proton resonance spacings over a wide range of mass number A=40-254. The present model prediction for the level densities is superior compared with those of the traditional Fermi-gas and the KRK-model. The present improvement seems to be due to considering the shell-pairing correlation terms in the analytic expression of single-particle state, and also to no use of the prescription for the effective excitation energy by using the so-called odd-even correction energy. (author)

  3. Ground-state electronic structure of actinide monocarbides and mononitrides

    Petit, Leon; Svane, Axel; Szotek, Z.;

    2009-01-01

    The self-interaction corrected local spin-density approximation is used to investigate the ground-state valency configuration of the actinide ions in the actinide monocarbides, AC (A=U,Np,Pu,Am,Cm), and the actinide mononitrides, AN. The electronic structure is characterized by a gradually...... the localization transition. The calculated valence electron densities of states are in good agreement with photoemission data....

  4. Parity dependence of the nuclear level density at high excitation

    The basic underlying assumption ρ(l+1, J)=ρ(l, J) in the level density function ρ(U, J, π) has been checked on the basis of high quality data available on individual resonance parameters (E0, Γn, Jπ) for s- and p-wave neutrons in contrast to the earlier analysis where information about p-wave resonance parameters was meagre. The missing level estimator based on the partial integration over a Porter-Thomas distribution of neutron reduced widths and the Dyson-Mehta Δ3 statistic for the level spacing have been used to ascertain that the s- and p-wave resonance level spacings D(0) and D(1) are not in error because of spurious and missing levels. The present work does not validate the tacit assumption ρ(l+1, J)=ρ(l, J) and confirms that the level density depends upon parity at high excitation. The possible implications of the parity dependence of the level density on the results of statistical model calculations of nuclear reaction cross sections as well as on pre-compound emission have been emphasized. (orig.)

  5. Effect of interstitial low level laser stimulation in skin density

    Jang, Seulki; Ha, Myungjin; Lee, Sangyeob; Yu, Sungkon; Park, Jihoon; Radfar, Edalat; Hwang, Dong Hyun; Lee, Han A.; Kim, Hansung; Jung, Byungjo

    2016-03-01

    As the interest in skin was increased, number of studies on skin care also have been increased. The reduction of skin density is one of the symptoms of skin aging. It reduces elasticity of skin and becomes the reason of wrinkle formation. Low level laser therapy (LLLT) has been suggested as one of the effective therapeutic methods for skin aging as in hasten to change skin density. This study presents the effect of a minimally invasive laser needle system (MILNS) (wavelength: 660nm, power: 20mW) in skin density. Rabbits were divided into three groups. Group 1 didn't receive any laser stimulation as a control group. Group 2 and 3 as test groups were exposed to MILNS with energy of 8J and 6J on rabbits' dorsal side once a week, respectively. Skin density of rabbits was measured every 12 hours by using an ultrasound skin scanner.

  6. The level density parameters for fermi gas model

    Nuclear level densities are crucial ingredient in the statistical models, for instance, in the calculations of the widths, cross sections, emitted particle spectra, etc. for various reaction channels. In this work 667 sets of more reliable and new experimental data are adopted, which include average level spacing DD, radiative capture width Γγ0 at neutron binding energy and cumulative level number N0 at the low excitation energy. They are published during 1973 to 1983. Based on the parameters given by Gilbert-Cameon and Cook the physical quantities mentioned above are calculated. The calculated results have the deviation obviously from experimental values. In order to improve the fitting, the parameters in the G-C formula are adjusted and new set of level density parameters is obsained. The parameters is this work are more suitable to fit new measurements

  7. Level density parameters for the Fermi gas model

    Zhuang Youxiang; Wang Cuilan; Zhou Chunmei; Su Zongdi

    1988-07-01

    Nuclear level densities are a crucial ingredient in the statistical models, for instance, in the calculations of the widths, cross sections, emitted particle spectra, etc. for various reaction channels. In this work 667 sets of more reliable and new experimental data are adopted, which include average level spacing D/sub 0/, radiative capture width GAMMA/sup 0//sub ..gamma../ at neutron binding energy, and cumulative level number N/sub 0/ at low excitation energy. They were published during 1973 to 1983. Based on the parameters given by Gilbert-Cameron and Cook the physical quantities mentioned above are calculated. The calculated results have the obvious deviations from the experimental values. In order to improve the fitting, the parameters in the G-C formula are adjusted and a new set of level density parameters is obtained. The parameters in this work are more suitable to fit new measurements.

  8. Level density parameters for the Fermi gas model

    Nuclear level densities are a crucial ingredient in the statistical models, for instance, in the calculations of the widths, cross sections, emitted particle spectra, etc. for various reaction channels. In this work 667 sets of more reliable and new experimental data are adopted, which include average level spacing D0, radiative capture width Γ0/sub γ/ at neutron binding energy, and cumulative level number N0 at low excitation energy. They were published during 1973 to 1983. Based on the parameters given by Gilbert-Cameron and Cook the physical quantities mentioned above are calculated. The calculated results have the obvious deviations from the experimental values. In order to improve the fitting, the parameters in the G-C formula are adjusted and a new set of level density parameters is obtained. The parameters in this work are more suitable to fit new measurements

  9. Microscopic Description of Nuclear Fission: Fission Barrier Heights of Even-Even Actinides

    McDonnell, J; Schunck, N; Nazarewicz, W.

    2013-01-01

    We evaluate the performance of modern nuclear energy density functionals for predicting inner and outer fission barrier heights and energies of fission isomers of even-even actinides. For isomer energies and outer barrier heights, we find that the self-consistent theory at the HFB level is capable of providing quantitative agreement with empirical data.

  10. Experimental studies of actinides in molten salts

    Reavis, J.G.

    1985-06-01

    This review stresses techniques used in studies of molten salts containing multigram amounts of actinides exhibiting intense alpha activity but little or no penetrating gamma radiation. The preponderance of studies have used halides because oxygen-containing actinide compounds (other than oxides) are generally unstable at high temperatures. Topics discussed here include special enclosures, materials problems, preparation and purification of actinide elements and compounds, and measurements of various properties of the molten volts. Property measurements discussed are phase relationships, vapor pressure, density, viscosity, absorption spectra, electromotive force, and conductance. 188 refs., 17 figs., 6 tabs.

  11. Experimental studies of actinides in molten salts

    This review stresses techniques used in studies of molten salts containing multigram amounts of actinides exhibiting intense alpha activity but little or no penetrating gamma radiation. The preponderance of studies have used halides because oxygen-containing actinide compounds (other than oxides) are generally unstable at high temperatures. Topics discussed here include special enclosures, materials problems, preparation and purification of actinide elements and compounds, and measurements of various properties of the molten volts. Property measurements discussed are phase relationships, vapor pressure, density, viscosity, absorption spectra, electromotive force, and conductance. 188 refs., 17 figs., 6 tabs

  12. Actinide burning and waste disposal

    Here we review technical and economic features of a new proposal for a synergistic waste-management system involving reprocessing the spent fuel otherwise destined for a U.S. high-level waste repository and transmuting the recovered actinides in a fast reactor. The proposal would require a U.S. fuel reprocessing plant, capable of recovering and recycling all actinides, including neptunium americium, and curium, from LWR spent fuel, at recoveries of 99.9% to 99.999%. The recovered transuranics would fuel the annual introduction of 14 GWe of actinide-burning liquid-metal fast reactors (ALMRs), beginning in the period 2005 to 2012. The new ALMRs would be accompanied by pyrochemical reprocessing facilities to recover and recycle all actinides from discharged ALMR fuel. By the year 2045 all of the LWR spent fuel now destined f a geologic repository would be reprocessed. Costs of constructing and operating these new reprocessing and reactor facilities would be borne by U.S. industry, from the sale of electrical energy produced. The ALMR program expects that ALMRs that burn actinides from LWR spent fuel will be more economical power producers than LWRs as early as 2005 to 2012, so that they can be prudently selected by electric utility companies for new construction of nuclear power plants in that era. Some leaders of DOE and its contractors argue that recovering actinides from spent fuel waste and burning them in fast reactors would reduce the life of the remaining waste to about 200-300 years, instead of 00,000 years. The waste could then be stored above ground until it dies out. Some argue that no geologic repositories would be needed. The current view expressed within the ALMR program is that actinide recycle technology would not replace the need for a geologic repository, but that removing actinides from the waste for even the first repository would simplify design and licensing of that repository. A second geologic repository would not be needed. Waste now planned

  13. ALMR potential for actinide consumption

    The Advanced Liquid Metal Reactor (ALMR) is a US Department of Energy (DOE) sponsored fast reactor design based on the Power Reactor, Innovative Small Module (PRISM) concept originated by General Electric. This reactor combines a high degree of passive safety characteristics with a high level of modularity and factory fabrication to achieve attractive economics. The current reference design is a 471 MWt modular reactor fueled with ternary metal fuel. This paper discusses actinide transmutation core designs that fit the design envelope of the ALMR and utilize spent LWR fuel as startup material and for makeup. Actinide transmutation may be accomplished in the ALMR core by using either a breeding or burning configuration. Lifetime actinide mass consumption is calculated as well as changes in consumption behavior throughout the lifetime of the reactor. Impacts on system operational and safety performance are evaluated in a preliminary fashion. Waste disposal impacts are discussed. (author)

  14. Methods for the determination of low-level actinide concentrations and their behaviour in the aquatic environment

    Intentional and accidental releases have contaminated the environment with radionuclides, posing a potential health hazard to populations of the polluted regions. Low concentrations of the actinides in the environment and complex sample matrices have made their determination a time consuming and complicated task. Separation methods based on anion exchange and extraction chromatography were developed, and subsequently modified, for analysis of different sample matrices in this work. These methods were used for the investigations of the behaviour of actinides in the environment. Chemical properties play an important role in the phenomena affecting the migration of radionuclides. The method based on anion exchange was used to study the behaviour of U in a small U-Th deposit and also the behaviour of Pu, Am and Cm in a lake system after the Chernobyl accident. The speciation of U and Pu in natural waters has also been investigated. A trend of higher 234U/238U activity ratios with lower 238U concentrations was seen in the ground waters in the Palmottu analogue study site in southern Finland. This indicates chemical leaching of U(VI) in oxidising conditions and preferable dissolution of 234U due to the recoil effects of the alpha decay in reducing conditions. The factors affecting the distribution of U concentrations and the 234U/238U activity ratios in filtered ground water and the particulate fraction in the Palmottu are also discussed. The concentrations of Pu, Am and Cm in filtered water, particulate and surface sediment samples in Lake Paeijaenne in southern Finland have been determined. Pu, Am and Cm fallout from the Chernobyl accident was minor compared to global fallout from atmospheric nuclear weapon tests. Based on the 238Pu/239,240Pu isotopic ratio, only 10 % of the Pu in the surface layer of the bottom sediment derived from the Chernobyl accident. Three months after the accident, 73 % of the total 239,240Pu concentration was in the surface layer of the bottom

  15. Methods for the determination of low-level actinide concentrations and their behaviour in the aquatic environment

    Pilvioe, R

    1998-12-31

    Intentional and accidental releases have contaminated the environment with radionuclides, posing a potential health hazard to populations of the polluted regions. Low concentrations of the actinides in the environment and complex sample matrices have made their determination a time consuming and complicated task. Separation methods based on anion exchange and extraction chromatography were developed, and subsequently modified, for analysis of different sample matrices in this work. These methods were used for the investigations of the behaviour of actinides in the environment. Chemical properties play an important role in the phenomena affecting the migration of radionuclides. The method based on anion exchange was used to study the behaviour of U in a small U-Th deposit and also the behaviour of Pu, Am and Cm in a lake system after the Chernobyl accident. The speciation of U and Pu in natural waters has also been investigated. A trend of higher {sup 234}U/{sup 238}U activity ratios with lower {sup 238}U concentrations was seen in the ground waters in the Palmottu analogue study site in southern Finland. This indicates chemical leaching of U(VI) in oxidising conditions and preferable dissolution of {sup 234}U due to the recoil effects of the alpha decay in reducing conditions. The factors affecting the distribution of U concentrations and the {sup 234}U/{sup 238}U activity ratios in filtered ground water and the particulate fraction in the Palmottu are also discussed. The concentrations of Pu, Am and Cm in filtered water, particulate and surface sediment samples in Lake Paeijaenne in southern Finland have been determined. Pu, Am and Cm fallout from the Chernobyl accident was minor compared to global fallout from atmospheric nuclear weapon tests. Based on the {sup 238}Pu/{sup 239,240}Pu isotopic ratio, only 10 % of the Pu in the surface layer of the bottom sediment derived from the Chernobyl accident. Three months after the accident, 73 % of the total {sup 239

  16. Combinatorial Level Densities from a Microscopic Relativistic Structure Model

    Pezer, R.; Ventura, A.; Vretenar, D.

    2002-01-01

    A new model for calculating nuclear level densities is investigated. The single-nucleon spectra are calculated in a relativistic mean-field model with energy-dependent effective mass, which yields a realistic density of single-particle states at the Fermi energy. These microscopic single-nucleon states are used in a fast combinatorial algorithm for calculating the non-collective excitations of nuclei. The method, when applied to magic and semi-magic nuclei, such as $^{60}$Ni, $^{114}$Sn and $...

  17. Generalized Freud's equation and level densities with polynomial potential

    Boobna, Akshat; Ghosh, Saugata

    2013-08-01

    We study orthogonal polynomials with weight $\\exp[-NV(x)]$, where $V(x)=\\sum_{k=1}^{d}a_{2k}x^{2k}/2k$ is a polynomial of order 2d. We derive the generalised Freud's equations for $d=3$, 4 and 5 and using this obtain $R_{\\mu}=h_{\\mu}/h_{\\mu -1}$, where $h_{\\mu}$ is the normalization constant for the corresponding orthogonal polynomials. Moments of the density functions, expressed in terms of $R_{\\mu}$, are obtained using Freud's equation and using this, explicit results of level densities as $N\\rightarrow\\infty$ are derived.

  18. Actinides analysis by accelerator mass spectrometry

    At the ANTARES accelerator at ANSTO a new beamline has been commissioned, incorporating new magnetic and electrostatic analysers, to optimise the efficiency for Actinides detection by Accelerator Mass Spectrometry (AMS). The detection of Actinides, particularly the isotopic ratios of uranium and plutonium, provide unique signatures for nuclear safeguards purposes. We are currently engaged in a project to evaluate the application of AMS to the measurement of Actinides in environmental samples for nuclear safeguards. Levels of certain fission products, Actinides and other radioactive species can be used as indicators of undeclared nuclear facilities or activities, either on-going or in the past Other applications of ultra-sensitive detection of Actinides are also under consideration. neutron-attenuation images of a porous reservoir rock

  19. The lanthanides and actinides

    This paper relates the chemical properties of the actinides to their position in the Mendeleev periodic system. The changes in the oxidation states of the actinides with increasing atomic number are similar to those of the 3d elements. Monovalent and divalent actinides are very similar to alkaline and alkaline earth elements; in the 3+ and 4+ oxidation states they resemble d elements in the respective oxidation states. However, in their highest oxidation states the actinides display their individual properties with only a slight resemblance to d elements. Finally, there is a profound similarity between the second half of the actinides and the first half of the lanthanides

  20. Superconductivity in rare earth and actinide compounds

    Rare earth and actinide compounds and the extraordinary superconducting and magnetic phenomena they exhibit are surveyed. The rare earth and actinide compounds described belong to three classes of novel superconducting materials: high temperature, high field superconductors (intermetallics and layered cuprates); superconductors containing localized magnetic moments; heavy fermion superconductors. Recent experiments on the resistive upper critical field of high Tc cuprate superconductors and the peak effect in the critical current density of the f-electron superconductor CeRu2 are discussed. (orig.)

  1. Level density and shape changes in excited sd shell nuclei

    S Santosh Kumar

    2008-07-01

    In the present calculation we have used the Monte Carlo method of generating collective spin and total energy of the nucleus for various configurations of the system with 0 single particle states available for n number of particles. The different configurations (arrangements of occupied single particle states) leading to a particular energy and spin are then collected to get the density of states for the given energy and spin . We find that if we use the cranked Nilsson model single particle states for the rotational frequency = 0.0ħω, 0.05ħω and 0.1ħω there is a shift in the maximum density of states max with a tendency for the system to become more oblate or prolate depending on the shift in the maximum density of states as the angular momentum decreases or increases. The change in nuclear level density with collectivity, i.e. with the use of cranked Nilsson model single particle levels has been noticed.

  2. Systematics of nuclear mass and level density formulas

    Nakamura, Hisashi [Fuji Electric Co. Ltd., Kawasaki, Kanagawa (Japan)

    1998-03-01

    The phenomenological models of the nuclear mass and level density are close related to each other, the nuclear ground and excited state properties are described by using the parameter systematics on the mass and level density formulas. The main aim of this work is to provide in an analytical framework the improved energy dependent shell, pairing and deformation corrections generalized to the collective enhancement factors, which offer a systematic prescription over a great number of nuclear reaction cross sections. The new formulas are shown to be in close agreement with not only the empirical nuclear mass data but the measured slow neutron resonance spacings, and experimental systematics observed in the excitation energy dependent properties. (author)

  3. Preparation of actinide targets by electrodeposition

    Trautmann, N.; Folger, H.

    1989-10-01

    Actinide targets with varying thicknesses on different substrates have been prepared by electrodeposition either from aqueous solutions or from solutions of their nitrates in isopropyl alcohol. With these techniques the actinides can be deposited almost quantitatively on various backing materials within 15 to 30 min. Targets of thorium, uranium, neptunium, plutonium, americium, curium and californium with areal densities from almost carrier-free up to 1.4 mg/cm 2 on thin beryllium, carbon, titanium, tantalum and platinum foils have been prepared. In most cases, prior to the deposition, the actinides had to be purified chemically and for some of them, due to the limited amount of material available, recycling procedures were required. Applications of actinide targets in heavy-ion reactions are briefly discussed.

  4. Evaluation of prompt neutron spectra for minor actinide nuclei

    Ohsawa, Takaaki [Kinki Univ., Higashi-Osaka, Osaka (Japan). Atomic Energy Research Inst.

    1997-03-01

    Measurement data on fission prompt neutron spectra of minor actinide (MA) is much little, and its accuracy is also unsufficient. Therefore, conventional evaluation value of fission spectra of MA was assumed for its nuclear temperature by using a method of determining from its systemicity owing to assumption of the Maxwell type distribution, but it can be said that this method consider fully to features of MA isotopes. In this paper, some evaluation calculation results are shown by adopting an evaluation method developed by authors and based on modified Madland Nix model and are conducted by concept of physical properties on target nuclei. As a result, by adopting the level density parameter of fission fragments, the inverse process cross section, the fission product yield distribution and the total release energy, effect of inverse process cross section, mass distribution of fission product, calculation results of Cm isotope and systemicity of fission spectra of actinide isotope were investigated. (G.K.)

  5. Decay rates of resonance states at high level density

    Rotter, Ingrid; Gorin, Thomas; Persson, E

    2010-01-01

    The time dependent Schrödinger equation of an open quantum mechanical system is solved by using the stationary bi-orthogonal eigenfunctions of the non-Hermitean time independent Hamilton operator. We calculate the decay rates at low and high level density in two different formalism. The rates are, generally, time dependent and oscillate around an average value due to the non-orthogonality of the wavefunctions. The decay law is studied disregarding the oscillations. In the one-channel case, it...

  6. Study of nuclear level densities for exotic nuclei

    M Nasri Nasrabadi

    2012-06-01

    Full Text Available Nuclear level density (NLD is one of the properties of nuclei with widespread applications in astrophysics and nuclear medicine. Since there has been little experimental and theoretical research on the study of nuclei which are far from stability line, studying NLD for these nuclei is of crucial importance. Also, as NLD is an important input for nuclear research codes, hence studying the methods for calculation of this parameter is essential. Besides introducing various methods and models for calculating NLD for practical applications, we used exact spectra distribution (SPDM for determining NLD of two neutron and proton enriched exotic nuclei with the same mass number.

  7. Nuclear level density parameter with Yukawa folded potential

    The average dependence of the single-particle level-density parameter on mass number A, isospin and deformation is determined using the Yukawa folded mean-field potential for spherical and deformed nuclei at temperatures 0 ≤ T ≤ 5 MeV and elongations ranging from oblate shapes to the scission configuration of fissioning nuclei. The results are compared with similar estimates obtained previously using the relativistic mean-field theory, the Skyrme Hartree-Fock and the Thomas-Fermi approach. (author)

  8. Quantum-Mechanical Analysis of Single-Particle Level Density

    Stetcu, I

    1997-01-01

    A quantum-mechanical calculation of the single-particle level (s.p.l.) density $g(\\epsilon)$ is carried on by using the connection with the single-particle Green's function. The relation between the imaginary part of Green's function and single-particle wave functions is used separately for the discrete and continuous states. Within the bound-states region the imaginary part of the Green's function is calculated by using the wronskian theorem. The Green's function corresponding to the continuum is written by using the regular and Jost solutions of the radial Schrodinger equation. The smooth part of the rapidly fluctuating s.p.l. density is calculated by means of the Strutinski procedure. The continuum component of the s.p.l. density has rather close values within either exact quantum-mechanical calculations with the Woods-Saxon (WS) potential, or Thomas-Fermi approximation with WS as well as finite-square potential wells, provided that the free-gas contribution is subtracted. A similar trend is obtained by me...

  9. Statistical inference of level densities from resolved resonance parameters

    Level densities are most directly obtained by counting the resonances observed in the resolved resonance range. Even in the measurements, however, weak levels are invariably missed so that one has to estimate their number and add it to the raw count. The main categories of missinglevel estimators are discussed in the present review, viz. (I) ladder methods including those based on the theory of Hamiltonian matrix ensembles (Dyson-Mehta statistics), (II) methods based on comparison with artificial cross section curves (Monte Carlo simulation, Garrison's autocorrelation method), (III) methods exploiting the observed neutron width distribution by means of Bayesian or more approximate procedures such as maximum-likelihood, least-squares or moment methods, with various recipes for the treatment of detection thresholds and resolution effects. The language of mathematical statistics is employed to clarify the basis of, and the relationship between, the various techniques. Recent progress in the treatment of resolution effects, detection thresholds and p-wave admixture is described. (orig.)

  10. Constraining the level density using fission of lead projectiles

    Rodríguez-Sánchez, J. L.; Benlliure, J.; Álvarez-Pol, H.; Audouin, L.; Ayyad, Y.; Bélier, G.; Boutoux, G.; Casarejos, E.; Chatillon, A.; Cortina-Gil, D.; Gorbinet, T.; Heinz, A.; Kelić-Heil, A.; Laurent, B.; Martin, J.-F.; Paradela, C.; Pellereau, E.; Pietras, B.; Ramos, D.; Rodríguez-Tajes, C.; Rossi, D. M.; Simon, H.; Taïeb, J.; Vargas, J.; Voss, B.

    2015-10-01

    The nuclear level density is one of the main ingredients for the statistical description of the fission process. In this work, we propose to constrain the description of this parameter by using fission reactions induced by protons and light ions on 208Pb at high kinetic energies. The experiment was performed at GSI (Darmstadt), where the combined use of the inverse kinematics technique with an efficient detection setup allowed us to measure the atomic number of the two fission fragments in coincidence. This measurement permitted us to obtain with high precision the partial fission cross sections and the width of the charge distribution as a function of the atomic number of the fissioning system. These data and others previously measured, covering a large range in fissility, are compared to state-of-the-art calculations. The results reveal that total and partial fission cross sections cannot unambiguously constrain the level density at ground-state and saddle-point deformations and additional observables, such as the width of the charge distribution of the final fission fragments, are required.

  11. Noninvasive liquid level/density measurement in pressure vessels

    This research investigated and demonstrated the principles of noninvasive detection of liquid level/density variations in a nuclear reactor pressure vessel. The noninvasive signal detection technique is based on using ex-vessel fast neutron detectors to sense variations in the escape rate of fast neutrons with changes in level/density in the pressure vessel. A prototype instrumentation package, deploying four fission chambers in a string, was developed and tested at the Penn State Breazeale Nuclear Reactor, as well as in six loss-of-coolant experiments at the Loss of Fluid Test Facility of the Idaho National Engineering Laboratory, Idaho Falls, Idaho. The six loss of coolant experiments consisted of two large break and four small break simulations. The prototype instrumentation package was microcomputer based, and was designed to operate in both current and pulse models. It tracked, accurately and quickly, the hydraulic conditions in the pressure vessel during these experiments. Analysis of its response data showed clear identification of: (a) downcomer voiding and refilling, (b) core voiding and refilling, (c) combined core and downcomer voiding and refilling, (d) top-down voiding and refilling of the core, (e) bottom-up voiding and refilling of the core, and (f) boiling and frothing in the pressure vessel. A set of algorithms for online detection and tracking of departure from normal hydraulic conditions is presented

  12. Actinide production in /sup 136/Xe bombardments of /sup 249/Cf

    Gregorich, K.E.

    1985-08-01

    The production cross sections for the actinide products from /sup 136/Xe bombardments of /sup 249/Cf at energies 1.02, 1.09, and 1.16 times the Coulomb barrier were determined. Fractions of the individual actinide elements were chemically separated from recoil catcher foils. The production cross sections of the actinide products were determined by measuring the radiations emitted from the nuclides within the chemical fractions. The chemical separation techniques used in this work are described in detail, and a description of the data analysis procedure is included. The actinide production cross section distributions from these /sup 136/Xe + /sup 249/Cf bombardments are compared with the production cross section distributions from other heavy ion bombardments of actinide targets, with emphasis on the comparison with the /sup 136/Xe + /sup 248/Cm reaction. A technique for modeling the final actinide cross section distributions has been developed and is presented. In this model, the initial (before deexcitation) cross section distribution with respect to the separation energy of a dinuclear complex and with respect to the Z of the target-like fragment is given by an empirical procedure. It is then assumed that the N/Z equilibration in the dinuclear complex occurs by the transfer of neutrons between the two participants in the dinuclear complex. The neutrons and the excitation energy are statistically distributed between the two fragments using a simple Fermi gas level density formalism. The resulting target-like fragment initial cross section distribution with respect to Z, N, and excitation energy is then allowed to deexcite by emission of neutrons in competition with fission. The result is a final cross section distribution with respect to Z and N for the actinide products. 68 refs., 33 figs., 6 tabs.

  13. Benchmarking mean-field approximations to level densities

    Alhassid, Y.; Bertsch, G. F.; Gilbreth, C. N.; Nakada, H.

    2016-04-01

    We assess the accuracy of finite-temperature mean-field theory using as a standard the Hamiltonian and model space of the shell model Monte Carlo calculations. Two examples are considered: the nucleus 162Dy, representing a heavy deformed nucleus, and 148Sm, representing a nearby heavy spherical nucleus with strong pairing correlations. The errors inherent in the finite-temperature Hartree-Fock and Hartree-Fock-Bogoliubov approximations are analyzed by comparing the entropies of the grand canonical and canonical ensembles, as well as the level density at the neutron resonance threshold, with shell model Monte Carlo calculations, which are accurate up to well-controlled statistical errors. The main weak points in the mean-field treatments are found to be: (i) the extraction of number-projected densities from the grand canonical ensembles, and (ii) the symmetry breaking by deformation or by the pairing condensate. In the absence of a pairing condensate, we confirm that the usual saddle-point approximation to extract the number-projected densities is not a significant source of error compared to other errors inherent to the mean-field theory. We also present an alternative formulation of the saddle-point approximation that makes direct use of an approximate particle-number projection and avoids computing the usual three-dimensional Jacobian of the saddle-point integration. We find that the pairing condensate is less amenable to approximate particle-number projection methods because of the explicit violation of particle-number conservation in the pairing condensate. Nevertheless, the Hartree-Fock-Bogoliubov theory is accurate to less than one unit of entropy for 148Sm at the neutron threshold energy, which is above the pairing phase transition. This result provides support for the commonly used "back-shift" approximation, treating pairing as only affecting the excitation energy scale. When the ground state is strongly deformed, the Hartree-Fock entropy is significantly

  14. Benchmarking mean-field approximations to level densities

    Alhassid, Y; Gilbreth, C N; Nakada, H

    2015-01-01

    We assess the accuracy of finite-temperature mean-field theory using as a standard the Hamiltonian and model space of the shell model Monte Carlo calculations. Two examples are considered: the nucleus $^{162}$Dy, representing a heavy deformed nucleus, and $^{148}$Sm, representing a nearby heavy spherical nucleus with strong pairing correlations. The errors inherent in the finite-temperature Hartree-Fock and Hartree-Fock-Bogoliubov approximations are analyzed by comparing the entropies of the grand canonical and canonical ensembles, as well as the level density at the neutron resonance threshold, with shell model Monte Carlo (SMMC) calculations, which are accurate up to well-controlled statistical errors. The main weak points in the mean-field treatments are seen to be: (i) the extraction of number-projected densities from the grand canonical ensembles, and (ii) the symmetry breaking by deformation or by the pairing condensate. In the absence of a pairing condensate, we confirm that the usual saddle-point appr...

  15. Spin Hamiltonians for actinide ions

    The breakdown of Russel Saunders coupling for correlated f-levels of actinide ions is due to both spin orbit coupling and the crystalline electric field (CEF). Experiments on curium, an S-state ion in the metal for which the CEF is weak indicate a g-factor close to the Russel-Saunders value. Spin-orbit coupling is therefore too weak to produce jj coupling. This suggests a model for magnetic actinide ions in which the CEF ground multiplet is well separated from higher levels, completely determining thermodynamic magnetic properties. On this basis simplified spin Hamiltonians are derived for GAMMA1-GAMMA5 ground states in order to interpret thermodynamic measurements and ordering phenomena. (author)

  16. Research in actinide chemistry

    This research studies the behavior of the actinide elements in aqueous solution. The high radioactivity of the transuranium actinides limits the concentrations which can be studied and, consequently, limits the experimental techniques. However, oxidation state analogs (trivalent lanthanides, tetravalent thorium, and hexavalent uranium) do not suffer from these limitations. Behavior of actinides in the environment are a major USDOE concern, whether in connection with long-term releases from a repository, releases from stored defense wastes or accidental releases in reprocessing, etc. Principal goal of our research was expand the thermodynamic data base on complexation of actinides by natural ligands (e.g., OH-, CO32-, PO43-, humates). The research undertakes fundamental studies of actinide complexes which can increase understanding of the environmental behavior of these elements

  17. PWRs potentialities for minor actinides burning

    In the frame of the SPIN program at CEA, the impacts of the Minor Actinides (MA) incineration in PWRs are analysed. The aim is to reduce the mass and the potential radiotoxicity level. This study is done separately one on the Plutonium recycling. But the plutonium is essential. Thus, the recycling of all Actinide elements is evaluated in a PWR nuclear yard. A sensitivity study is done to evaluate the incineration for each Minor Actinide element. This gives us the most efficient way of incineration for each MA element in a PWR and help us to design a PWR burner. This burner is disposed in a PWR nuclear system in which the Actinides are recycled until equilibrium. (authors). 2 refs

  18. Density and wave function analysis of actinide complexes: What can fuzzy atom, atoms-in-molecules, Mulliken, Löwdin, and natural population analysis tell us?

    Clark, Aurora E.; Sonnenberg, Jason L.; Hay, P. Jeffrey; Martin, Richard L.

    2004-08-01

    Recent advances in computational methods have made it possible to calculate the wave functions for a wide variety of simple actinide complexes. Equally important is the ability to analyze the information contained therein and produce a chemically meaningful understanding of the electronic structure. Yet the performance of the most common wave function analyses for the calculation of atomic charge and bond order has not been thoroughly investigated for actinide systems. This is particularly relevant because the calculation of charge and bond order even in transition metal complexes is known to be fraught with difficulty. Here we use Mulliken, Löwdin, natural population analysis, atoms-in-molecules (AIM), and fuzzy atom techniques to determine the charges and bond orders of UO22+, PuO22+, UO2, UO2Cl42-, UO2(CO)52+, UO2(CO)42+, UO2(CN)53-, UO2(CN)42-, UO2(OH)53-, and UO2(OH)42-. This series exhibits a clear experimental and computational trend in bond lengths and vibrational frequencies. The results indicate that Mulliken and Löwdin populations and bond orders are unreliable for the actinyls. Natural population analysis performs well after modification of the partitioning of atomic orbitals to include the 6d in the valence space. The AIM topological partitioning is insensitive to the electron donating ability of the equatorial ligands and the relative atomic volume of the formally U(VI) center is counterintuitively larger than that of O2- in the UO22+ core. Lastly, the calibrated fuzzy atom method yields reasonable bond orders for the actinyls at significantly reduced computational cost relative to the AIM analysis.

  19. Evaluation of actinide partitioning and transmutation

    After a few centuries of radioactive decay the long-lived actinides, the elements of atomic numbers 89-103, may constitute the main potential radiological health hazard in nuclear wastes. This is because all but a very few fission products (principally technetium-99 and iodine-129) have by then undergone radioactive decay to insignificant levels, leaving the actinides as the principal radionuclides remaining. It was therefore at first sight an attractive concept to recycle the actinides to nuclear reactors, so as to eliminate them by nuclear fission. Thus, investigations of the feasibility and potential benefits and hazards of the concept of 'actinide partitioning and transmutation' were started in numerous countries in the mid-1970s. This final report summarizes the results and conclusions of technical studies performed in connection with a four-year IAEA Co-ordinated Research Programme, started in 1976, on the ''Environmental Evaluation and Hazard Assessment of the Separation of Actinides from Nuclear Wastes followed by either Transmutation or Separate Disposal''. Although many related studies are still continuing, e.g. on waste disposal, long-term safety assessments, and waste actinide management (particularly for low and intermediate-level wastes), some firm conclusions on the overall concept were drawn by the programme participants, which are reflected in this report

  20. Molecular cluster theory of chemical bonding in actinide oxide

    The electronic structure of actinide monoxides AcO and dioxides AcO2, where Ac = Th, U, Np, Pu, Am, Cm and Bk has been studied by molecular cluster methods based on the first-principles one-electron local density theory. Molecular orbitals for nearest neighbor clusters AcO10-6 and AcO12-8 representative of monoxide and dioxide lattices were obtained using non-relativistic spin-restricted and spin-polarized Hartree-Fock-Slater models for the entire series. Fully relativistic Dirac-Slater calculations were performed for ThO, UO and NpO in order to explore magnitude of spin-orbit splittings and level shifts in valence structure. Self-consistent iterations were carried out for NpO, in which the NpO6 cluster was embedded in the molecular field of the solid. Finally, a ''moment polarized'' model which combines both spin-polarization and relativistic effects in a consistent fashion was applied to the NpO system. Covalent mixing of oxygen 2p and Ac 5f orbitals was found to increase rapidly across the actinide series; metal s,p,d covalency was found to be nearly constant. Mulliken atomic population analysis of cluster eigenvectors shows that free-ion crystal field models are unreliable, except for the light actinides. X-ray photoelectron line shapes have been calculated and are found to compare rather well with experimental data on the dioxides

  1. Anthropogenic Actinides in the Environment

    The use of nuclear energy and the testing of nuclear weapons have led to significant releases of anthropogenic isotopes, in particular a number of actinide isotopes generally not abundant in nature. Most prominent amongst these are 239Pu, 240Pu, and 236U. The study of these actinides in nature has been an active field of study ever since. Measurements of actinides are applied to nuclear safeguards, investigating the sources of contamination, and as a tracer for a number of erosion and hydrology studies. Accelerator Mass Spectrometry (AMS) is ideally suited for these studies and generally offers higher sensitivities than competing techniques, like ICP-MS or decay counting. Recent advances in AMS allow the study of “minor” plutonium isotopes (241Pu, 242Pu, and 244Pu). Furthermore, 236U can now be measured at the levels expected from the global stratospheric fall-out of the atmospheric nuclear weapon tests in the 1950s and 1960s. Even the pre-anthropogenic isotope ratios could be within reach. However, the distribution and abundance levels of these isotopes are not well known yet. I will present an overview of the field, and in detail two recent studies on minor plutonium isotopes and 236U, respectively.(author)

  2. Level Density Parameter: A Tool to Study the Particle Spectra

    The compound nucleus 76Kr* is formed in the heavy-ion fusion reactions by an asymmetric entrance channel 12C+64Zn and the symmetric entrance channel 31P+45Sc at the excitation energy of 75 MeV and angular momentum of 39 η. Neutron energy spectra of the asymmetric system (12C+64Zn) at different angles are well described by the statistical model predictions using the normal value of the level density parameter a = A/8 MeV-1. However, in the case of the symmetric system (31P+45Sc), the statistical model interpretation of the data requires the change in the value of a = A/10 MeV-1. The delayed evolution of the compound system in case of the symmetric 31P+45Sc system may lead to the formation of a temperature equilibrated dinuclear complex, which may be responsible for the neutron emission at higher temperature, while the protons and alpha particles are evap orated after neutron emission when the system is sufficiently cooled down and the higher λ-values do not contribute in the formation of the compound nucleus for the symmetric entrance channel in case of charged particle emission.

  3. Separation of trivalent actinides and lanthanides from simulated high-level waste using cobalt bis(dicarbollide) ion derivate substituted with diphenyl-N-tert.octyl-carbamoylmethylphosphine oxide

    Selucký, P.; Lučaníková, M.; Grüner, Bohumír

    2012-01-01

    Roč. 100, č. 3 (2012), s. 179-183. ISSN 0033-8230 R&D Projects: GA MŠk LC523; GA ČR GA104/09/0668 Institutional research plan: CEZ:AV0Z40320502 Keywords : dicarbollide * CMPO * liquid-liquid extraction * actinides * lanthanides Subject RIV: CA - Inorganic Chemistry Impact factor: 1.373, year: 2012

  4. Research in actinide chemistry

    1991-01-01

    This report contains research results on studies of inorganic and organic complexes of actinide and lanthanide elements. Special attention is given to complexes of humic acids and to spectroscopic studies.

  5. A Laplace-like formula for the energy dependence of the nuclear level density parameter

    Canbula, Bora; Canbula, Deniz; Babacan, Halil

    2014-01-01

    Collective effects in the level density are not well understood, and including these effects as enhancement factors to the level density does not produce sufficiently consistent predictions of observables. Therefore, collective effects are investigated in the level density parameter instead of treating them as a final factor in the level density. A new Laplace-like formula is proposed for the energy dependence of the level density parameter, including collective effects. A significant improvement has been achieved in agreement between observed and predicted energy levels. This new model can also be used in both structure and reaction calculations of the nuclei far from stability, especially near the drip lines.

  6. A Laplace-like formula for the energy dependence of the nuclear level density parameter

    Collective effects in the level density are not well understood, and including these effects as enhancement factors to the level density does not produce sufficiently consistent predictions of observables. Therefore, collective effects are investigated in the level density parameter instead of treating them as a final factor in the level density. A new Laplace-like formula is proposed for the energy dependence of the level density parameter, including collective effects. A significant improvement has been achieved in agreement between observed and predicted energy levels. This new model can also be used in both structure and reaction calculations of the nuclei far from stability, especially near the drip lines

  7. Work within the coordinated programme on environmental evaluation and hazard assessment of the separation of the actinides from the high-level waste from fuel reprocessing followed by either transmutation of separate disposal

    Reduction of plutonium losses in non-high-level wastes streams from fuel reprocessing is important in the conventional post-fission operations and would be essential in any actinide partitioning alternatives. The balance of input process streams and output waste streams in present reprocessing technology is compared to the balance after process modifications based on recent experimental developments. The results are showing that by the introduction of new electrochemical redox processes and non-salt-forming process chemicals the routinely generated intermediate-level waste streams from PUREX reprocessing can be avoided. Plutonium-bearing waste streams can be extensively recycled within the chemical processing

  8. Use of organophosphorus extractants impregnated on silica gel for the extraction chromatographic separation of minor actinides from high level waste solutions

    Silica-gel has been used as an inert support for the extraction chromatographic separation of actinides and lanthanides from HNO3 and synthetic high level waste (HLW) solutions. Silica-gel was impregnated with tri-butyl phosphate (TBP), to yield STBP; 2-ethylhexyl phosphonic acid, mono 2-ethylhexyl ester (KSM-17, equivalent to PC-88A), SKSM; octyl(phenyl)-N,N-diisobutyl carbamoylmethylphosphine oxide (CMPO), SCMPO; and trialkylphosphine oxide (Cyanex-923), SCYN and sorption of Pu(IV), Am(III) and Eu(III) from HNO3 solutions was studied batchwise. Several parameters, like time of equilibration, HNO3 and Pu(IV) concentrations were varied. The uptake of Pu(IV) from 3.0M HNO3 followed the order SCMPO>SCYN>SKSM>STBP. With increasing HNO3 concentration, DPu increased up to 3.0M of HNO3 for STBP, SKSM and SCMPO and then decreased. In the case of Am and Eu with SCMPO, the D values initially increased between 0.5 to 1.0M of HNO3, remained constant up to 5.0M and then slightly decreased at 7.5M. Also, the effects of NaNO3, Nd(III) and U(VI) concentrations on the uptake of Am(III) from HNO3 solutions were evaluated. With increasing NaNO3 concentration up to 3.0M, DAm remained almost constant while it was observed that it decreases drastically by adding Nd(III) or U(VI). The uptake of Pu and Am from synthetic pressurized heavy water reactor high level waste (PHWR-HLW) in presence of high concentrations of uranium and after depleting the uranium content, and finally extraction chromatographic column separation of Pu and Am from U-depleted synthetic PHWR-HLW have been carried out. Using SCMPO, high sorption of Pu, Am and U was obtained from the U-depleted HLW solution. These metal ions were subsequently eluted using various reagents. The sorption results of the metal ions on silica-gel impregnated with several phosphorus based extractants have been compared. The uptake of Am, Pu and rare earths by SCMPO has been compared with those where CMPO was sorbed on Chromosorb-102

  9. Waste disposal aspects of actinide separation

    Two recent NRPB reports are summarized (Camplin, W.C., Grimwood, P.D. and White, I.F., The effects of actinide separation on the radiological consequences of disposal of high-level radioactive waste on the ocean bed, Harwell, National Radiological Protection Board, NRPB-R94 (1980), London, HMSO; Hill, M.D., White, I.F. and Fleishman, A.B., The effects of actinide separation on the radiological consequences of geologic disposal of high-level waste. Harwell, National Radiological Protection Board, NRPB-R95 (1980), London, HMSO). They describe preliminary environmental assessments relevant to waste arising from the reprocessing of PWR fuel. Details are given of the modelling of transport of radionuclides to man, and of the methodology for calculating effective dose equivalents in man. Emphasis has been placed on the interaction between actinide separation and the disposal options rather than comparison of disposal options. The reports show that the effects of actinide separation do depend on the disposal method. Conditions are outlined where the required substantial further research and development work on actinide separation and recycle would be justified. Toxicity indices or 'toxic potentials' can be misleading and should not be used to guide research and development. (U.K.)

  10. Use of fast reactors for actinide transmutation

    The management of radioactive waste is one of the key issues in today's discussions on nuclear energy, especially the long term disposal of high level radioactive wastes. The recycling of plutonium in liquid metal fast breeder reactors (LMFBRs) would allow 'burning' of the associated extremely long life transuranic waste, particularly actinides, thus reducing the required isolation time for high level waste from tens of thousands of years to hundreds of years for fission products only. The International Working Group on Fast Reactors (IWGFR) decided to include the topic of actinide transmutation in liquid metal fast breeder reactors in its programme. The IAEA organized the Specialists Meeting on Use of Fast Breeder Reactors for Actinide Transmutation in Obninsk, Russian Federation, from 22 to 24 September 1992. The specialists agree that future progress in solving transmutation problems could be achieved by improvements in: Radiochemical partitioning and extraction of the actinides from the spent fuel (at least 98% for Np and Cm and 99.9% for Pu and Am isotopes); technological research and development on the design, fabrication and irradiation of the minor actinides (MAs) containing fuels; nuclear constants measurement and evaluation (selective cross-sections, fission fragments yields, delayed neutron parameters) especially for MA burners; demonstration of the feasibility of the safe and economic MA burner cores; knowledge of the impact of maximum tolerable amount of rare earths in americium containing fuels. Refs, figs and tabs

  11. Actinide isotopic analysis systems

    This manual provides instructions and procedures for using the Lawrence Livermore National Laboratory's two-detector actinide isotope analysis system to measure plutonium samples with other possible actinides (including uranium, americium, and neptunium) by gamma-ray spectrometry. The computer program that controls the system and analyzes the gamma-ray spectral data is driven by a menu of one-, two-, or three-letter options chosen by the operator. Provided in this manual are descriptions of these options and their functions, plus detailed instructions (operator dialog) for choosing among the options. Also provided are general instructions for calibrating the actinide isotropic analysis system and for monitoring its performance. The inventory measurement of a sample's total plutonium and other actinides content is determined by two nondestructive measurements. One is a calorimetry measurement of the sample's heat or power output, and the other is a gamma-ray spectrometry measurement of its relative isotopic abundances. The isotopic measurements needed to interpret the observed calorimetric power measurement are the relative abundances of various plutonium and uranium isotopes and americium-241. The actinide analysis system carries out these measurements. 8 figs

  12. The coupling of capillary electrophoresis-inductively coupled plasma mass spectrometer as a speciation instrument for actinides at trace level; Le couplage electrophorese capillaire-spectrometre de masse a source plasma en tant qu'instrument de speciation des actinides a l'etat de traces

    Delorme, A

    2004-07-01

    An interface between the separation technique (capillary electrophoresis) and the analytical technique (Inductively Coupled Plasma - Mass Spectrometer) was developed. In that sense, bibliographic and parametric studies allowed to define necessary conditions for the good working of both techniques. The results obtained led to the realisation of an interface capillary electrophoresis / ICP-MS (CE / ICP-MS). This one was experimentally validated on classical separations (alkalis / earth-alkalis and lanthanides) and the detection limit of the analytical system was determined equal to 4 x 10{sup -11} mol.L{sup -1} for plutonium. This result exhibits a gain in detection limit of a factor higher than 10{sup 4} compared to the capillary electrophoresis in standard detection (UV). The studies were made in order to check the capacity of the CE / ICP-MS coupling as a speciation instrument for actinides at trace level and to define the associated analytical procedures. The coupling turned out to be a suited instrument for the determination of absolute electrophoretic mobilities at infinite dilution (physico-chemical property which allows to predict the migration time of an ion under an electrical field in a given electrolyte), for the determination of thermodynamic constants and for the separation of different actinide oxidation states in solution. (author)

  13. Actinides and Life's Origins.

    Adam, Zachary

    2007-12-01

    There are growing indications that life began in a radioactive beach environment. A geologic framework for the origin or support of life in a Hadean heavy mineral placer beach has been developed, based on the unique chemical properties of the lower-electronic actinides, which act as nuclear fissile and fertile fuels, radiolytic energy sources, oligomer catalysts, and coordinating ions (along with mineralogically associated lanthanides) for prototypical prebiotic homonuclear and dinuclear metalloenzymes. A four-factor nuclear reactor model was constructed to estimate how much uranium would have been required to initiate a sustainable fission reaction within a placer beach sand 4.3 billion years ago. It was calculated that about 1-8 weight percent of the sand would have to have been uraninite, depending on the weight percent, uranium enrichment, and quantity of neutron poisons present within the remaining placer minerals. Radiolysis experiments were conducted with various solvents with the use of uraniumand thorium-rich minerals (metatorbernite and monazite, respectively) as proxies for radioactive beach sand in contact with different carbon, hydrogen, oxygen, and nitrogen reactants. Radiation bombardment ranged in duration of exposure from 3 weeks to 6 months. Low levels of acetonitrile (estimated to be on the order of parts per billion in concentration) were conclusively identified in 2 setups and tentatively indicated in a 3(rd) by gas chromatography/mass spectrometry. These low levels have been interpreted within the context of a Hadean placer beach prebiotic framework to demonstrate the promise of investigating natural nuclear reactors as power production sites that might have assisted the origins of life on young rocky planets with a sufficiently differentiated crust/mantle structure. Future investigations are recommended to better quantify the complex relationships between energy release, radioactive grain size, fissionability, reactant phase, phosphorus

  14. Electronic structure and ionicity of actinide oxides from first principles

    Petit, Leon; Svane, Axel; Szotek, Z.;

    2010-01-01

    The ground-state electronic structures of the actinide oxides AO, A2O3, and AO2 (A=U, Np, Pu, Am, Cm, Bk, and Cf) are determined from first-principles calculations, using the self-interaction corrected local spin-density approximation. Emphasis is put on the degree of f-electron localization, which...... actinide dioxides is discussed, and it is found that the dioxide is the most stable oxide for the actinides from Np onward. Our study reveals a strong link between preferred oxidation number and degree of localization which is confirmed by comparing to the ground-state configurations of the corresponding...

  15. Radiochemistry and actinide chemistry

    The analysis of trace amounts of actinide elements by means of radiochemistry, is discussed. The similarities between radiochemistry and actinide chemistry, in the case of species amount by cubic cm below 1012, are explained. The parameters which allow to define what are the observable chemical reactions, are given. The classification of radionuclides in micro or macrocomponents is considered. The validity of the mass action law and the partition function in the definition of the average number of species for trace amounts, is investigated. Examples illustrating the results are given

  16. Sorption Speciation of Lanthanides/Actinides on Minerals by TRLFS, EXAFS and DFT Studies: A Review

    Xiaoli Tan

    2010-11-01

    Full Text Available Lanthanides/actinides sorption speciation on minerals and oxides by means of time resolved laser fluorescence spectroscopy (TRLFS, extended X-ray absorption fine structure spectroscopy (EXAFS and density functional theory (DFT is reviewed in the field of nuclear disposal safety research. The theoretical aspects of the methods are concisely presented. Examples of recent research results of lanthanide/actinide speciation and local atomic structures using TRLFS, EXAFS and DFT are discussed. The interaction of lanthanides/actinides with oxides and minerals as well as their uptake are also of common interest in radionuclide chemistry. Especially the sorption and inclusion of radionuclides into several minerals lead to an improvement in knowledge of minor components in solids. In the solid-liquid interface, the speciation and local atomic structures of Eu(III, Cm(III, U(VI, and Np(IV/VI in several natural and synthetic minerals and oxides are also reviewed and discussed. The review is important to understand the physicochemical behavior of lanthanides/actinides at a molecular level in the natural environment.

  17. The electronic structure of the lanthanides and actinides, a comparison

    Full text: Optical spectra of the two f-element series (the lanthanides and actinides) are comparable in many respects. For the trivalent ions isolated in single crystals, both series exhibit rich, narrow line spectra. These data can be analysed in terms of a parametric model based on a free-ion Hamiltonian plus the addition of a crystal field Hamiltonian. For most systems the agreement between the calculated and experimental energy levels is quite good. In the actinide series there appears to be a correlation between the magnitude of the crystal field and the inadequacy of the fits. The early actinides exhibit multiple oxidation states for which there is no precedent in the lanthanide series. The parametric model mentioned earlier has been utilized for some tetravalent actinide systems with reasonably good results. A selective survey of results describing the similarities and differences of various lanthanide and actinide systems will be given

  18. Stochastic estimation of nuclear level density in the nuclear shell model: An application to parity-dependent level density in 58Ni

    Noritaka Shimizu

    2016-02-01

    Full Text Available We introduce a novel method to obtain level densities in large-scale shell-model calculations. Our method is a stochastic estimation of eigenvalue count based on a shifted Krylov-subspace method, which enables us to obtain level densities of huge Hamiltonian matrices. This framework leads to a successful description of both low-lying spectroscopy and the experimentally observed equilibration of Jπ=2+ and 2− states in 58Ni in a unified manner.

  19. Feasibility studies of actinide recycle in LMFBRs as a waste management alternative

    A strategy of actinide burnup in LMFBRs is being investigated as a waste management alternative to long term storage of high level nuclear waste. This strategy is being evaluated because many of the actinides in the waste from spent-fuel reprocessing have half-lives of thousands of years and an alternative to geological storage may be desired. From a radiological viewpoint, the actinides and their daughters dominate the waste hazard for decay times beyond about 400 years. Actinide burnup in LMFBRs may be an attractive alternative to geological storage because the actinides can be effectively transmuted to fission products which have significantly shorter half-lives. Actinide burnup in LMFBRs rather than LWRs is preferred because the ratio of fission reaction rate to capture reaction rate for the actinides is higher in an LMFBR, and an LMFBR is not so sensitive to the addition of the actinide isotopes. An actinide target assembly recycle scheme is evaluated to determine the effects of the actinides on the LMFBR performance, including local power peaking, breeding ratio, and fissile material requirements. Several schemes are evaluated to identify any major problems associated with reprocessing and fabrication of recycle actinide-containing assemblies. The overall efficiency of actinide burnout in LMFBRs is evaluated, and equilibrium cycle conditions are determined. It is concluded that actinide recycle in LMFBRs offers an attractive alternative to long term storage of the actinides, and does not significantly affect the performance of the host LMFBR. Assuming a 0.1 percent or less actinide loss during reprocessing, a 0.1 percent loss of less during fabrication, and proper recycle schemes, virtually all of the actinides produced by a fission reactor economy could be transmuted in fast reactors

  20. Level density fluctuations at the bottom of a potential well

    We evaluate trace formulas for various perturbations of two-dimensional harmonic oscillators. Such systems arise naturally in the expansion of generic potentials about local minima. For large enough perturbations, the usual theory for isolated orbits applies and we can reproduce the long and medium-range oscillators in the density of states in terms of the shortest periodic orbits. For small perturbations or low energies, the Gutzwiller amplitudes diverge due to the approaching degeneracy of the harmonic oscillator. We employ a perturbative analysis of the classical dynamics to give a treatment of the trace formula that is valid near the degenerate harmonic regime. First order perturbation theory works for generic cases. For certain potentials, such as Henon-Heiles, discrete symmetries lead to a null result at first order and second order calculations are necessary to capture the dominant features. (authors)

  1. Actinides in Solution: Disproportionation, Strong Correlations, and Emergence

    Marston, Brad; Horowitz, Steven

    2010-03-01

    Plutonium in acid solutions can be found in oxidation states III through VI. There is a striking near perfect degeneracy of the reduction-oxidation (redox) potentials, each being about 1 volt. Neptunium is the only other element that approaches this degree of degeneracy. One consequence of the redox degeneracy is a marked tendency of plutonium ions to disproportionate; up to four different oxidation states can coexist simultaneously in the same solution, greatly complicating the environmental chemistry of the element. While the degeneracy could simply be a coincidence, it could also be the manifestation of a higher-level organizing principle at work. Other systems that exhibit disproportionation raise the possibility of an emergent negative-U attractive interaction. The hypothesis is tested by combining first-principles relativistic density-functional calculations using the Amsterdam Density Functional (ADF) package with exact diagonalizations of Hubbard-like models of the strong correlations between the actinide 5f electrons.

  2. Actinide separative chemistry

    Actinide separative chemistry has focused very heavy work during the last decades. The main was nuclear spent fuel reprocessing: solvent extraction processes appeared quickly a suitable, an efficient way to recover major actinides (uranium and plutonium), and an extensive research, concerning both process chemistry and chemical engineering technologies, allowed the industrial development in this field. We can observe for about half a century a succession of Purex plants which, if based on the same initial discovery (i.e. the outstanding properties of a molecule, the famous TBP), present huge improvements at each step, for a large part due to an increased mastery of the mechanisms involved. And actinide separation should still focus R and D in the near future: there is a real, an important need for this, even if reprocessing may appear as a mature industry. We can present three main reasons for this. First, actinide recycling appear as a key-issue for future nuclear fuel cycles, both for waste management optimization and for conservation of natural resource; and the need concerns not only major actinide but also so-called minor ones, thus enlarging the scope of the investigation. Second, extraction processes are not well mastered at microscopic scale: there is a real, great lack in fundamental knowledge, useful or even necessary for process optimization (for instance, how to design the best extracting molecule, taken into account the several notifications and constraints, from selectivity to radiolytic resistivity?); and such a need for a real optimization is to be more accurate with the search of always cheaper, cleaner processes. And then, there is room too for exploratory research, on new concepts-perhaps for processing quite new fuels- which could appear attractive and justify further developments to be properly assessed: pyro-processes first, but also others, like chemistry in 'extreme' or 'unusual' conditions (supercritical solvents, sono-chemistry, could be

  3. Level density of $^{56}$Fe and low-energy enhancement of $\\gamma$-strength function

    Voinov, A. V.; Grimes, S. M.; Agvaanluvsan, U.; Algin, E.; Belgya, T.; Brune, C. R.; Guttormsen, M.; Hornish, M. J.; T. Massey; Mitchell, G. E.; Rekstad, J.; Schiller, A.; Siem, S.

    2006-01-01

    The $^{55}$Mn$(d,n)^{56}$Fe differential cross section is measured at $E_d=7$ MeV\\@. The $^{56}$Fe level density obtained from neutron evaporation spectra is compared to the level density extracted from the $^{57}$Fe$(^3$He,$\\alpha\\gamma)^{56}$Fe reaction by the Oslo-type technique. Good agreement is found between the level densities determined by the two methods. With the level density function obtained from the neutron evaporation spectra, the $^{56}$Fe $\\gamma$-strength function is also de...

  4. Shampoo, Soy Sauce, and the Prince's Pendant: Density for Middle-Level Students

    Chandrasekhar, Meera; Litherland, Rebecca

    2006-01-01

    In this article, the authors describe a series of activities they have used with middle-level students. The first set of lessons explores density through the layering of liquids. In the second set, they use some of the same liquids to explore the density of solids. The third set investigates how temperature affects the density of…

  5. IAEA advisory group meeting on basic and applied problems of nuclear level densities

    Bhat, M.R. (ed.)

    1983-06-01

    Separate entries were made in the data base for 17 of the 19 papers included. Two papers were previously included in the data base. Workshop reports are included on (1) nuclear level density theories and nuclear model reaction cross-section calculations and (2) extraction of nuclear level density information from experimental data. (WHK)

  6. IAEA advisory group meeting on basic and applied problems of nuclear level densities

    Separate entries were made in the data base for 17 of the 19 papers included. Two papers were previously included in the data base. Workshop reports are included on (1) nuclear level density theories and nuclear model reaction cross-section calculations and (2) extraction of nuclear level density information from experimental data

  7. The role of the nuclear level density in spallation neutron studies

    The influence of the nuclear level density parameters of the various nuclides determined recently on the neutron yields, produced by 0.8--1.4 GeV proton bombardments of thick tungsten target, was investigated. The results show that better agreement between measurements and LAHET calculations is achieved on the basis of a new set of level density parameters

  8. A general iteration scheme for the calculation of level densities, and results using a semiclassical approximation

    A general scheme is derived to calculate m-particle n-hole fermion level densities for any single particle Hamiltonian taking into account Pauli exclusion. This technique is applied to obtain level densities of the three dimensional isotropic Harmonic Oscillator semiclassically in the Thomas-Fermi approach

  9. Photochemistry of the actinides

    It has been found that all three major actinides have a useful variety of photochemical reactions which could be used to achieve a separations process that requires fewer reagents. Several features merit enumerating: (1) Laser photochemistry is not now as uniquely important in fuel reprocessing as it is in isotopic enrichment. The photochemistry can be successfully accomplished with conventional light sources. (2) The easiest place to apply photo-reprocessing is on the three actinides U, Pu, and Np. The solutions are potentially cleaner and more amenable to photoreactions. (3) Organic-phase photoreactions are probably not worth much attention because of the troublesome solvent redox chemistry associated with the photochemical reaction. (4) Upstream process treatment on the raffinate (dissolver solution) may never be too attractive since the radiation intensity precludes the usage of many optical materials and the nature of the solution is such that light transmission into it might be totally impossible

  10. Recent advances in the microscopic calculations of level densities by the shell model Monte Carlo method

    The shell model Monte Carlo (SMMC) method enables calculations in model spaces that are many orders of magnitude larger than those that can be treated by conventional methods, and is particularly suitable for the calculation of level densities in the presence of correlations. We review recent advances and applications of SMMC for the microscopic calculation of level densities. Recent developments include (1) a method to calculate accurately the ground-state energy of an odd-mass nucleus, circumventing a sign problem that originates in the projection on an odd number of particles, and (2) a method to calculate directly level densities, which, unlike state densities, do not include the spin degeneracy of the levels. We calculated the level densities of a family of nickel isotopes 59-64Ni and of a heavy deformed rare-earth nucleus 162Dy and found them to be in close agreement with various experimental data sets. (author)

  11. Recent Advances in the Microscopic Calculations of Level Densities by the Shell Model Monte Carlo Method

    Alhassid, Y; Liu, S; Mukherjee, A; Nakada, H

    2014-01-01

    The shell model Monte Carlo (SMMC) method enables calculations in model spaces that are many orders of magnitude larger than those that can be treated by conventional methods, and is particularly suitable for the calculation of level densities in the presence of correlations. We review recent advances and applications of SMMC for the microscopic calculation of level densities. Recent developments include (i) a method to calculate accurately the ground-state energy of an odd-mass nucleus, circumventing a sign problem that originates in the projection on an odd number of particles, and (ii) a method to calculate directly level densities, which, unlike state densities, do not include the spin degeneracy of the levels. We calculated the level densities of a family of nickel isotopes $^{59-64}$Ni and of a heavy deformed rare-earth nucleus $^{162}$Dy and found them to be in close agreement with various experimental data sets.

  12. Status report on actinide and fission product transmutation studies

    The management of radioactive waste is one of the key issues in today's political and public discussions on nuclear energy. One of the fields that looks into the future possibilities of nuclear technology is the neutronic transmutation of actinides and of some most important fission products. Studies on transmutation of actinides are carried out in various countries and at an international level. This status report which gives an up-to-date general overview of current and planned research on transmutation of actinides and fission products in non-OECD countries, has been prepared by a Technical Committee meeting organized by the IAEA in September 1995. 168 refs, 16 figs, 34 tabs

  13. Actinide interactions at microbial interfaces: an interdisciplinary challenge

    An overview on the current state of knowledge of microbial actinide interaction processes is presented. Several detailed examples of the interaction of aerobic soil bacteria (Pseudomonas, Bacillus and Deinococcus strains) with uranium and plutonium are discussed. Details of the nature of the bacterial functional groups involved in the interfacial actinide interaction process are reported. Based on time-resolved laser-induced fluorescence spectroscopy (TRLFS) and synchrotron X-ray absorption spectroscopy (XANES and EXAFS) studies, molecular-level mechanistic details of the different interaction processes are discussed. Areas of this emerging field in actinide research are outlined where additional information and integrated interdisciplinary research is required

  14. Separating the Minor Actinides Through Advances in Selective Coordination Chemistry

    Lumetta, Gregg J.; Braley, Jenifer C.; Sinkov, Sergey I.; Carter, Jennifer C.

    2012-08-22

    This report describes work conducted at the Pacific Northwest National Laboratory (PNNL) in Fiscal Year (FY) 2012 under the auspices of the Sigma Team for Minor Actinide Separation, funded by the U.S. Department of Energy Office of Nuclear Energy. Researchers at PNNL and Argonne National Laboratory (ANL) are investigating a simplified solvent extraction system for providing a single-step process to separate the minor actinide elements from acidic high-level liquid waste (HLW), including separating the minor actinides from the lanthanide fission products.

  15. Fast neutron scattering on actinide nuclei

    More and more sophisticated neutron experiments have been carried out with better samples in several laboratories and it was necessary to intercompare them. In this respect, let us quote for example (n,n'e) and (n,n'#betta#) measurements. Moreover, high precision (p,p), (p,p') and (p,n) measurements have been made, thus supplementing neutron experiments in the determination of the parameters of the optical model, still widely used to describe the neutron-nucleus interaction. The optical model plays a major role and it is therefore essential to know it well. The spherical optical model is still very useful, especially because of its simplicity and of the relatively short calculation times, but is obviously insufficient to treat deformed nuclei such as actinides. For accurate calculations about these nuclei, it is necessary to use a deformed potential well and solve a set of coupled equations, hence long computational times. The importance of compound nucleus formation at low energy requires also a good knowledge of the statistical model together with that of all the reaction mechanisms which are involved, including fission for which an accurate barrier is necessary and, of course, well-adjusted level densities. The considerations form the background of the Scientific Programme set up by a Programme Committee whose composition is given further on in this book

  16. On the universality of the long-/short-range separation in multiconfigurational density-functional theory. II. Investigating f0 actinide species

    Fromager, Emmanuel; Réal, Florent; Wåhlin, Pernilla; Wahlgren, Ulf; Jensen, Hans Jørgen Aagaard

    2009-01-01

    investigation of a universal range separation. The accuracy of the currently best MC-srDFT (μ=0.3 a.u.) approach has also been tested for equilibrium geometries. Though it performs as well as wave function theory and DFT for static-correlation-free systems, it fails in describing the neptunyl (VII) ion NpO23......+ where static correlation is significant; bending is preferred at the MC-srDFT (μ=0.3 a.u.) level, whereas the molecule is known to be linear. This clearly shows the need for better short-range functionals, especially for the description of the short-range exchange. It also suggests that the bending...... tendencies observed in DFT for NpO23+ cannot be fully explained by the bad description of static correlation effects by standard functionals. A better description of the exchange seems to be essential too....

  17. Actinides: why are they important biologically

    The following topics are discussed: actinide elements in energy systems; biological hazards of the actinides; radiation protection standards; and purposes of actinide biological research with regard to toxicity, metabolism, and therapeutic regimens

  18. Photoelectron spectra of actinide compounds

    A brief overview of the application of photoelectron spectroscopy is presented for the study of actinide materials. Phenomenology as well as specific materials are discussed with illustrative examples

  19. Separation of actinides from spent nuclear fuel: A review.

    Veliscek-Carolan, Jessica

    2016-11-15

    This review summarises the methods currently available to extract radioactive actinide elements from solutions of spent nuclear fuel. This separation of actinides reduces the hazards associated with spent nuclear fuel, such as its radiotoxicity, volume and the amount of time required for its' radioactivity to return to naturally occurring levels. Separation of actinides from environmental water systems is also briefly discussed. The actinide elements typically found in spent nuclear fuel include uranium, plutonium and the minor actinides (americium, neptunium and curium). Separation methods for uranium and plutonium are reasonably well established. On the other hand separation of the minor actinides from lanthanide fission products also present in spent nuclear fuel is an ongoing challenge and an area of active research. Several separation methods for selective removal of these actinides from spent nuclear fuel will be described. These separation methods include solvent extraction, which is the most commonly used method for radiochemical separations, as well as the less developed but promising use of adsorption and ion-exchange materials. PMID:27427893

  20. Gas core reactors for actinide transmutation. [uranium hexafluoride

    Clement, J. D.; Rust, J. H.; Wan, P. T.; Chow, S.

    1979-01-01

    The preliminary design of a uranium hexafluoride actinide transmutation reactor to convert long-lived actinide wastes to shorter-lived fission product wastes was analyzed. It is shown that externally moderated gas core reactors are ideal radiators. They provide an abundant supply of thermal neutrons and are insensitive to composition changes in the blanket. For the present reactor, an initial load of 6 metric tons of actinides is loaded. This is equivalent to the quantity produced by 300 LWR-years of operation. At the beginning, the core produces 2000 MWt while the blanket generates only 239 MWt. After four years of irradiation, the actinide mass is reduced to 3.9 metric tonnes. During this time, the blanket is becoming more fissile and its power rapidly approaches 1600 MWt. At the end of four years, continuous refueling of actinides is carried out and the actinide mass is held constant. Equilibrium is essentially achieved at the end of eight years. At equilibrium, the core is producing 1400 MWt and the blanket 1600 MWt. At this power level, the actinide destruction rate is equal to the production rate from 32 LWRs.

  1. Nuclear level densities with pairing and self-consistent ground-state shell effects

    Nuclear level density calculations are performed using a model of fermions interacting via the pairing force, and a realistic single particle potential. The pairing interaction is treated within the BCS approximation with different pairing strength values. The single particle potentials are derived in the framework of an energy-density formalism which describes self-consistently the ground states of spherical nuclei. These calculations are extended to statically deformed nuclei, whose estimated level densities include rotational band contributions. The theoretical results are compared with various experimental data. In addition, the level densities for several nuclei far from stability are compared with the predictions of a back-shifted Fermi gas model. Such a comparison emphasizes the possible danger of extrapolating to unknown nuclei classical level density formulae whose parameter values are tailored for known nuclei. (orig.)

  2. A comparative simulation study of data-driven methods for estimating density level sets

    Saavedra-Nieves, Paula; González-Manteiga, Wenceslao; Rodríguez-Casal, Alberto

    2014-01-01

    Density level sets are mainly estimated using one of three methodologies: plug-in, excess mass, or a hybrid approach. The plug-in methods are based on replacing the unknown density by some nonparametric estimator, usually the kernel. Thus, the bandwidth selection is a fundamental problem from a practical point of view. Recently, specific selectors for level sets have been proposed. However, if some a priori information about the geometry of the level set is available, then excess mass algorit...

  3. Microscopic calculation of level densities: the shell model Monte Carlo approach

    The shell model Monte Carlo (SMMC) approach provides a powerful technique for the microscopic calculation of level densities in model spaces that are many orders of magnitude larger than those that can be treated by conventional methods. We discuss a number of developments: (i) Spin distribution. We used a spin projection method to calculate the exact spin distribution of energy levels as a function of excitation energy. In even-even nuclei we find an odd-even staggering effect (in spin). Our results were confirmed in recent analysis of experimental data. (ii) Heavy nuclei. The SMMC approach was extended to heavy nuclei. We have studied the crossover between vibrational and rotational collectivity in families of samarium and neodymium isotopes in model spaces of dimension approx. 1029. We find good agreement with experimental results for both state densities and 2> (where J is the total spin). (iii) Collective enhancement factors. We have calculated microscopically the vibrational and rotational enhancement factors of level densities versus excitation energy. We find that the decay of these enhancement factors in heavy nuclei is correlated with the pairing and shape phase transitions. (iv) Odd-even and odd-odd nuclei. The projection on an odd number of particles leads to a sign problem in SMMC. We discuss a novel method to calculate state densities in odd-even and odd-odd nuclei despite the sign problem. (v) State densities versus level densities. The SMMC approach has been used extensively to calculate state densities. However, experiments often measure level densities (where levels are counted without including their spin degeneracies.) A spin projection method enables us to also calculate level densities in SMMC. We have calculated the SMMC level density of 162Dy and found it to agree well with experiments

  4. Actinides: from heavy fermions to plutonium metallurgy

    The actinide elements mark the emergence of 5f electrons. The f electrons possess sufficiently unusual characteristics that their participation in atomic binding often result in dramatic changes in properties. This provides an excellent opportunity to study the question of localization of electrons; a question that is paramount in predicting the physical and chemical properties of d and f electron transition metals. The transition region between localized (magnetic) and itinerant (often superconducting) behavior provides for many interesting phenomena such as structural instabilities (polymorphism), spin fluctuations, mixed valences, charge density waves, exceptional catalytic activity and hydrogen storage. This region offers most interesting behavior such as that exhibited by the actinide compounds UBe13 and UPt3. Both compounds are heavy-fermion superconductors in which both magnetic and superconducting behavior exist in the same electrons. The consequences of f-electron bonding (which appears greatest at Plutonium) show dramatic effects on phase stability, alloying behavior, phase transformations and mechanical behavior

  5. Landau theory of nuclear level density and its application in description of nuclear level density in the region of discrete and s-wave neutron resonance energies

    Elmas, A; Gonul, B

    2016-01-01

    In this work, the reliability of the Landau expression for the nuclear level density calculations is tested, for the first-time, to describe nuclear level densities of some light, intermediate mass and heavy nuclei at excitations corresponding to discrete and s-wave neutron resonance energies. The chi-2 minimizing method is used in treatment of the experimental data for the two suggested energy range of discrete energies given by Nuclear Data Sheet [1] and by the systematic for nuclear level density parametrization in [2]. Our comparison with the related data in the discrete energy range has shown that the results obtained by the Landau expression are better than those of back-shifted Fermi-gas model and constant temperature approximation. This result is also valid for some nuclei of interest when the s-wave neutron resonance level density is included to check theoretical prescriptions in the energy range from initial bound states to unbound states near the neutron binding energy.

  6. Beyond High-Density Lipoprotein Cholesterol Levels: Evaluating High-Density Lipoprotein Function as Influenced by Novel Therapeutic Approaches

    deGoma, Emil M.; deGoma, Rolando L.; Rader, Daniel J.

    2008-01-01

    A number of therapeutic strategies targeting high-density lipoprotein (HDL) cholesterol and reverse cholesterol transport are being developed to halt the progression of atherosclerosis or even induce regression. However, circulating HDL cholesterol levels alone represent an inadequate measure of therapeutic efficacy. Evaluation of the potential effects of HDL-targeted interventions on atherosclerosis requires reliable assays of HDL function and surrogate markers of efficacy. Promotion of macr...

  7. Actinide recovery from pyrochemical residues

    We demonstrated a new process for recovering plutonium and americium from pyrochemical waste. The method is based on chloride solution anion exchange at low acidity, or acidity that eliminates corrosive HCl fumes. Developmental experiments of the process flow chart concentrated on molten salt extraction (MSE) residues and gave >95% plutonium and >90% americium recovery. The recovered plutonium contained 62- from high-chloride low-acid solution. Americium and other metals are washed from the ion exchange column with lN HNO3-4.8M NaCl. After elution, plutonium is recovered by hydroxide precipitation, and americium is recovered by NaHCO3 precipitation. All filtrates from the process can be discardable as low-level contaminated waste. Production-scale experiments are in progress for MSE residues. Flow charts for actinide recovery from electro-refining and direct oxide reduction residues are presented and discussed

  8. Bone density and hemoglobin levels in older persons: results from the InCHIANTI study.

    Cesari, Matteo; Pahor, Marco; Lauretani, Fulvio; Penninx, Brenda W H J; Bartali, Benedetta; Russo, Roberto; Cherubini, Antonio; Woodman, Richard; Bandinelli, Stefania; Guralnik, Jack M; Ferrucci, Luigi

    2005-06-01

    Hypoxemia has been recognized as a risk factor for bone loss. The aim of the present study is to investigate the relationship of bone mass and density measures with anemia and hemoglobin levels in a large sample of older community-dwelling persons. The study is based on data from 950 participants enrolled in the "Invecchiare in Chianti" (Aging in the Chianti area, InCHIANTI) study. All the analyses were performed considering continuous hemoglobin levels as well as the dichotomous anemia variable (defined according to WHO criteria as hemoglobin < 12 g/dl in women and < 13 g/dl in men). A peripheral quantitative computerized tomography (pQCT) scan of the right calf was performed in all participants to evaluate total bone density, trabecular bone density, cortical bone density, and the ratio between cortical and total bone area. Linear regression analyses were used to assess the multivariate relationship of pQCT bone measures with anemia and hemoglobin levels after adjustment for demographics, chronic conditions, muscle strength and biological variables. Participants were 75.0 (SD 6.9) years old. In our sample, 101 participants (10.6%) were anemic. In women, coefficients from adjusted linear regression analyses evaluating the association between pQCT bone measures (per SD increase) and hemoglobin levels/anemia showed significant associations of anemia with total bone density (beta = -0.335, SE = 0.163; P = 0.04) and cortical bone density (beta = -0.428, SE = 0.160; P = 0.008). Relationships with borderline significance were found for the associations of anemia with trabecular bone density and the ratio between cortical and total bone area. Significant associations were found between hemoglobin levels and trabecular bone density (beta = 0.112, SE = 0.049; P = 0.02), total bone density (beta = 0.101, SE = 0.046; P = 0.03), cortical bone density (beta = 0.100, SE = 0.046; P = 0.03) and the ratio between cortical bone and total area (beta = 0.092, SE = 0.045; P = 0

  9. Leaching of actinides from nuclear waste glass: French experience

    The activity concentration versus time of a typical LWR glass shows that after 300 years most of the activity is attributable to three actinides (Np, Pu and Am) and to 99Tc. This activity decreases slowly, and some 50.000 years are necessary before the activity concentration drops to the level of the richest natural ores. This paper reviews the current state of knowledge concerning the kinetics of actinide release from glass subjected to aqueous leaching

  10. Level densities and $\\gamma$-ray strength functions in Sn isotopes

    Toft, H. K.; Larsen, A.C.; Agvaanluvsan, U.; Bürger, A.; Guttormsen, M.; Mitchell, G. E.; Nyhus, H. T.; Schiller, A.; Siem, S.; Syed, N. U. H.; Voinov, A.

    2010-01-01

    The nuclear level densities of $^{118,119}$Sn and the $\\gamma$-ray strength functions of $^{116,118,119}$Sn below the neutron separation energy are extracted with the Oslo method using the ($^3$He, \\,$\\alpha \\gamma$) and ($^3$He,$^3$He$^\\prime\\gamma$) reactions. The level density function of $^{119}$Sn displays step-like structures. The microcanonical entropies are deduced from the level densities, and the single neutron entropy of $^{119}$Sn is determined to be $(1.7 \\pm 0.2)\\,k_B$. Results ...

  11. Study on Subcritical System Disposing Plutonium and High-level Actinides%次临界系统处理钚及高放锕系元素的概念研究

    沈姚崧; 刘成安

    2000-01-01

    对加速器驱动的次临界反应堆处理反应堆级钚和高放锕系废物进行了概念性设计的研究.建立了以液态铋系合金金属为载热剂的次临界堆芯模型,利用ADVBISON程序对该问题进行了数值计算,得到了满意的中子学、燃耗和放射性衰变等结果.%Disposition of the reactor-plutonium and high-level actinides by usingaccelerator-driven subcritical reactor was studied theoretically and the corresponding core model using liquid Bi-alloy as the reactor coolant was proposed. The satisfied numerical results of neutronics, burn-up and radioactivity were obtained by the ADVBISON code.

  12. Library of Recommended Actinide Decay Data, 2011

    A major objective of the nuclear data programme within the IAEA is to devise and promote improvements in the quality of nuclear data used in science and technology. Work of this nature was performed by participants in an IAEA coordinated research project (CRP) formulated in 2005 to produce an updated decay data library of important actinides recommended for adoption in various nuclear applications. The specific objectives of this project were to improve the accuracy of heavy element and actinide decay data in order to: determine more accurately the effects of these recommended data on fission reactor fuel cycles; aid in improved assessments of nuclear waste management procedures; provide more reliable decay data for nuclear safeguards; assess with greater confidence the environmental impact of specific actinides and other heavy element radionuclides generated through their decay chains; and extend the scientific knowledge of actinide decay characteristics for nuclear physics research and non-energy applications. Some CRP participants were able to perform a number of highly precise measurements, based on the availability of suitable source materials, and systematic in depth evaluations of the requested decay data. These requested data consisted primarily of half-lives, and α, β-, EC/β+, Auger electron, conversion electron, X ray and γ ray energies and emission probabilities, all with uncertainties expressed at the 1σ confidence level. The IAEA established a CRP entitled Updated Decay Data Library for Actinides in mid-2005. During the course of discussions at the coordinated research meetings, the participants agreed to undertake work programmes of measurements and evaluations, to be completed by the end of 2010. The results of the evaluation studies undertaken by the CRP are presented in Annex I. Annexes II-V include descriptions of the sources of the evaluated decay data and each individual evaluation process in detail, as well as data files in the Evaluated

  13. Optical techniques for actinide research

    In recent years, substantial gains have been made in the development of spectroscopic techniques for electronic properties studies. These techniques have seen relatively small, but growing, application in the field of actinide research. Photoemission spectroscopies, reflectivity and absorption studies, and x-ray techniques will be discussed and illustrative examples of studies on actinide materials will be presented

  14. Evaluation study on silica/polymer-based CA-BTP adsorbent for the separation of minor actinides from simulated high-level liquid wastes

    A silica/polymer-based CA-BTP/SiO2-P adsorbent was prepared to separate minor actinides and some key radionuclides from HLLW. The adsorption properties of CA-BTP/SiO2-P toward 238U(VI), 239Pu(IV), 241Am(III), 99Tc(VII), 152Eu(III), and some typical fission products were studied. CA-BTP/SiO2-P stability against c-radiation was also evaluated. It found CA-BTP/SiO2-P showed very poor adsorption abilities toward U(VI) and most experimental FPs, while CA-BTP/SiO2-P exhibited higher adsorption abilities toward 241Am(III), 239Pu(IV), and 99Tc(VII) in 0.5-1 M HNO3 solution. Moreover, dry CA-BTP/SiO2-P demonstrated no instability when the radiation dose was up to 161 kGy. CA-BTP/SiO2-P adsorbent is a potential candidate for separating 241Am(III), 239Pu(IV), and 99Tc(VII) from HLLW. (author)

  15. At last, competitive microscopic predictions of nuclear masses and nuclear level densities

    A microscopic HF-BCS formula for nuclear masses, and a new nuclear level density formula within the microscopic statistical approach and based on the above mentioned HF-BCS method, are briefly presented

  16. Level density of $^{56}$Fe and low-energy enhancement of $\\gamma$-strength function

    Voinov, A V; Agvaanluvsan, U; Algin, E; Belgya, T; Brune, C R; Guttormsen, M; Hornish, M J; Massey, T; Mitchell, G E; Rekstad, J; Schiller, A; Siem, S

    2006-01-01

    The $^{55}$Mn$(d,n)^{56}$Fe differential cross section is measured at $E_d=7$ MeV\\@. The $^{56}$Fe level density obtained from neutron evaporation spectra is compared to the level density extracted from the $^{57}$Fe$(^3$He,$\\alpha\\gamma)^{56}$Fe reaction by the Oslo-type technique. Good agreement is found between the level densities determined by the two methods. With the level density function obtained from the neutron evaporation spectra, the $^{56}$Fe $\\gamma$-strength function is also determined from the first-generation $\\gamma$ matrix of the Oslo experiment. The good agreement between the past and present results for the $\\gamma$-strength function supports the validity of both methods and is consistent with the low-energy enhancement of the $\\gamma$ strength below $\\sim 4$ MeV first discovered by the Oslo method in iron and molybdenum isotopes.

  17. Studying nuclear level densities of 238U in the nuclear reactions within the macroscopic nuclear models

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

  18. Use of fast-spectrum reactors for actinide burning

    Finally, Integral Fast Reactor (IFR) pyroprocessing has been developed only in recent years and it appears to have potential as a relatively uncomplicated, effective actinide recovery process. In fact, actinide recycling occurs naturally in the IFR fuel cycle. Although still very much developmental, the entire IFR fuel cycle will be demonstrated on prototype-scale in conjunction with the EBR-II and its refurbished Fuel Cycle Facility starting in late 1991. A logical extension to this work, therefore, is to establish whether this IFR pyrochemical processing can be applied to extracting actinides from LWR spent fuel. This paper summarizes current thinking on the rationale for actinide recycle, its ramifications on the geologic repository and the current high-level waste management plans, and the necessary development programs. 4 figs., 4 tabs

  19. A High Power Density Three-level Parallel Resonant Converter for Capacitor Charging

    Sheng, Honggang

    2009-01-01

    This dissertation proposes a high-power, high-frequency and high-density three-level parallel resonant converter for capacitor charging. DC-DC pulsed power converters are widely used in military and medical systems, where the power density requirement is often stringent. The primary means for reducing the power converter size has been to reduce loss for reduced cooling systems and to increase the frequency for reduced passive components. Three-level resonant converters, which combine the mer...

  20. The shell model Monte Carlo approach to level densities: recent developments and perspectives

    Alhassid, Y

    2016-01-01

    We review recent advances in the shell model Monte Carlo approach for the microscopic calculation of statistical and collective properties of nuclei. We discuss applications to the calculation of (i) level densities in nickel isotopes, implementing a recent method to circumvent the odd-particle sign problem; (ii) state densities in heavy nuclei; (iii) spin distributions of nuclear levels; and (iv) finite-temperature quadrupole distributions.

  1. Study Of Cascade Intensity And Level Density Of 52V By (n, 2γ) Reaction

    The cascade intensity and level density in neutron capture reaction are reviewed cross section and gamma strength function of nuclear. This newspaper showed some results the cascade intensity and level density are reviewed cross section and gamma strength function in the lower binding energy of neutron (Bn) with 52V by Summation of Amplitudes of Coinciding Pulses method (SACP). This experiment was measured on channel 3 of the Dalat nuclear reactor. (author)

  2. The shell model Monte Carlo approach to level densities: Recent developments and perspectives

    Alhassid, Y. [Yale University, Center for Theoretical Physics, Sloane Physics Laboratory, New Haven, Connecticut (United States)

    2015-12-15

    We review recent advances in the shell model Monte Carlo approach for the microscopic calculation of statistical and collective properties of nuclei. We discuss applications to the calculation of i) level densities in nickel isotopes, implementing a recent method to circumvent the odd-particle sign problem; ii) state densities in heavy nuclei; iii) spin distributions of nuclear levels; and iv) finite-temperature quadrupole distributions. (orig.)

  3. The shell model Monte Carlo approach to level densities: Recent developments and perspectives

    Alhassid, Y.

    2015-12-01

    We review recent advances in the shell model Monte Carlo approach for the microscopic calculation of statistical and collective properties of nuclei. We discuss applications to the calculation of i) level densities in nickel isotopes, implementing a recent method to circumvent the odd-particle sign problem; ii) state densities in heavy nuclei; iii) spin distributions of nuclear levels; and iv) finite-temperature quadrupole distributions.

  4. Effects of level density parameter on the superheavy production in cold fusion

    Pahlavani, M. R.; Alavi, S. A.

    2014-12-01

    By using semiclassical method and considering Woods-Saxon and Coulomb potentials, the level density parameter a was calculated for three superheavy nuclei 270110, 278112 and 290116. Obtained results showed that the value of level density parameter of these nuclei is near to the simple relation a ≈ A/10. In framework of the dinuclear system model, the effects of level density parameter on the probability of the formation of a compound nucleus, the ratio of neutron emission width and fission width, and evaporation residue cross-section of three cold fusion reactions 62Ni+208Pb, 70Zn+208Pb and 82Se+208Pb, leading to superheavy elements were investigated. The findings indicate that the level density parameter play a significant role in calculations of heavy-ion fusion-fission reactions. The obtained results in the case of a = A/12 have larger values in comparison with calculated level density parameter with Woods-Saxon potential (aWS) and a = A/10. The theoretical results of the evaporation residue cross-section are very sensitive to the choice of level density parameter. The calculated values with aWS are in good agreement with experimental values.

  5. Strength of Coriolis alignment in actinide nuclei

    Analysis of aligned angular momenta i/sub α/(ω) in different rotational bands extracted from experimental data with a linear spin term approx.BI in the formulas for E/sub rot/(I) reveal that, in actinide nuclei in the levels with modest spin I< or =23, i/sub α/(ω) usually is very small (< or approx. =0.7), i.e., is much smaller than in rare earth nuclei

  6. Thermal properties of minor actinide targets

    Staicu, Dragos; Somers, Joseph; FERNANDEZ CARRETERO Asuncion; KONINGS Rudy

    2014-01-01

    The thermal properties of minor actinides targets for the management of high level and long lived radioactive waste are investigated. The microstructure, thermal diffusivity and specific heat of (Pu,Am)O2, (Zr,Pu,Am)O2, (Zr,Y,Am)O2, (Zr,Y,Pu,Am)O2 and CERMETS with Mo matrix are characterised in order to assess the safety limits of these materials.

  7. ACTINEX Programme: experimental results and conceptual solvent extraction processes for minor actinide partitioning

    An improvement in the management of high level nuclear wastes, generated by nuclear fuel reprocessing operations, may be expected by decreasing the amount of long-lived alpha emitter minor actinide (Np, Am and Cm) radionuclides contained in these wastes. This goal can be achieve by chemical and nuclear processes designed to: 1/ extract the minor actinides from the high level liquid waste; 2/ incinerate the recovered actinides into short lived radionuclides. This present paper deals with recent results obtained at the CEA in the field of minor actinide partitioning. (author). 17 refs., 2 figs

  8. Evaluation of average neutron resonance parameters of actinides with the account of experimental resolution and discrimination threshold. Final report for the period 15 December 1996 - 14 December 1997

    New evaluation of average resonance parameters for 32 isotopes of the actinide region (229Th-252Cf) was completed. Obtained values of average level spacings produce a smooth systematics of the main level density parameter. The results were included into the Starter File of the Reference Input Parameter Library (segment Average Neutron Resonances) and officially released on 15 May 1998. The numerical results are available from the Internet (http://iaeand.iaea.or.at/ripl) and on CD-ROM. (author)

  9. Characterization of actinides in simulated alkaline tank waste sludges and leach solutions

    Current plans call for an alkaline scrub of actinide-bearing sludges in the Hanford Waste tanks prior to their incorporation in glass waste forms. Though it is assumed that actinides will remain in the sludge phase during this procedure, this assumption is based on insufficient supporting thermodynamic and kinetic data. In this project the authors will investigate the fundamental chemistry of actinides in strongly alkaline solution and solid phases to strengthen the foundation and identify potential limitations of this approach. They will focus on the characterization of the leaching of actinides from simulated BiPO4, REDOX, and PUREX sludges, the identification of actinide mineral phases in the sludge simulants, and the possible solubilization of actinides by complexation and radiolysis effects. This program will provide new fundamental information on the chemical behavior and speciation of uranium, neptunium, plutonium, and americium in simulated alkaline tank waste sludges and alkaline scrub liquors. Sludge simulants will be prepared from the appropriate matrix components using published data for guidance. Actinide ions will be introduced in the oxidation states pertinent to process conditions. The authors will characterize the speciation of the actinides in the sludges using a variety of techniques. In parallel studies, they will address the chemistry of actinide ions in alkaline solutions, principally those containing chelating agents. The third critical element of this research will be to assess the impact of radiolysis on actinide behavior. By correlating actinide speciation in the solid and solution phases with sludge composition, it will be possible to predict conditions favoring mobilization (or immobilization) of actinide ions during sludge washing. The new information will increase predictability of actinide behavior during tank sludge washing, and so contribute to minimization of the volume of high level waste created

  10. Cell density related gene expression: SV40 large T antigen levels in immortalized astrocyte lines

    Jacobberger James W

    2002-04-01

    Full Text Available Abstract Background Gene expression is affected by population density. Cell density is a potent negative regulator of cell cycle time during exponential growth. Here, we asked whether SV40 large T antigen (Tag levels, driven by two different promoters, changed in a predictable and regular manner during exponential growth in clonal astrocyte cell lines, immortalized and dependent on Tag. Results Expression and cell cycle phase fractions were measured and correlated using flow cytometry. T antigen levels did not change or increased during exponential growth as a function of the G1 fraction and increasing cell density when Tag was transcribed from the Moloney Murine Leukemia virus (MoMuLV long terminal repeat (LTR. When an Rb-binding mutant T antigen transcribed from the LTR was tested, levels decreased. When transcribed from the herpes thymidine kinase promoter, Tag levels decreased. The directions of change and the rates of change in Tag expression were unrelated to the average T antigen levels (i.e., the expression potential. Conclusions These data show that Tag expression potential in these lines varies depending on the vector and clonal variation, but that the observed level depends on cell density and cell cycle transit time. The hypothetical terms, expression at zero cell density and expression at minimum G1 phase fraction, were introduced to simplify measures of expression potential.

  11. Study of the parity ratio of nuclear level density near neutron binding energy

    Now much new improved data on the s- and p- wave level spacings D0 and D1 based on neutron resonances have been accumulated and it seems quite worthwhile to check the aspect of parity dependence of nuclear level density in view of its great significance to nuclear reaction theories

  12. Managing Inventories of Heavy Actinides

    The Department of Energy (DOE) has stored a limited inventory of heavy actinides contained in irradiated targets, some partially processed, at the Savannah River Site (SRS) and Oak Ridge National Laboratory (ORNL). The 'heavy actinides' of interest include plutonium, americium, and curium isotopes; specifically 242Pu and 244Pu, 243Am, and 244/246/248Cm. No alternate supplies of these heavy actinides and no other capabilities for producing them are currently available. Some of these heavy actinide materials are important for use as feedstock for producing heavy isotopes and elements needed for research and commercial application. The rare isotope 244Pu is valuable for research, environmental safeguards, and nuclear forensics. Because the production of these heavy actinides was made possible only by the enormous investment of time and money associated with defense production efforts, the remaining inventories of these rare nuclear materials are an important part of the legacy of the Nuclear Weapons Program. Significant unique heavy actinide inventories reside in irradiated Mark-18A and Mark-42 targets at SRS and ORNL, with no plans to separate and store the isotopes for future use. Although the costs of preserving these heavy actinide materials would be considerable, for all practical purposes they are irreplaceable. The effort required to reproduce these heavy actinides today would likely cost billions of dollars and encompass a series of irradiation and chemical separation cycles for at least 50 years; thus, reproduction is virtually impossible. DOE has a limited window of opportunity to recover and preserve these heavy actinides before they are disposed of as waste. A path forward is presented to recover and manage these irreplaceable National Asset materials for future use in research, nuclear forensics, and other potential applications.

  13. Orthometric corrections from leveling, gravity, density and elevation data: a case study in Taiwan

    Hwang, C.; Hsiao, Y.-S.

    2003-08-01

    A new orthometric correction (OC) formula is presented and tested with various mean gravity reduction methods using leveling, gravity, elevation, and density data. For mean gravity computations, the Helmert method, a modified Helmert method with variable density and gravity anomaly gradient, and a modified Mader method were used. An improved method of terrain correction computation based on Gaussian quadrature is used in the modified Mader method. These methods produce different results and yield OCs that are greater than 10 cm between adjacent benchmarks (separated by sim2 km) at elevations over 3000 m. Applying OC reduces misclosures at closed leveling circuits and improves the results of leveling network adjustments. Variable density yields variation of OC at millimeter level everywhere, while gravity anomaly gradient introduces variation of OC of greater than 10 cm at higher elevations, suggesting that these quantities must be considered in OC. The modified Mader method is recommended for computing OC.

  14. Nuclear level densities and gamma-ray strength functions in 44,45Sc

    Larsen, A C; Chankova, R; Lönnroth, T; Messelt, S; Ingebretsen, F; Rekstad, J; Schiller, A; Siem, S; Syed, N U H; Voinov, A

    2007-01-01

    The scandium isotopes 44,45Sc have been studied with the 45Sc(3He,alpha gamma)44Sc and 45Sc(3He,3He' gamma)45Sc reactions, respectively. The nuclear level densities and gamma-ray strength functions have been extracted using the Oslo method. The experimental level densities are compared to calculated level densities obtained from a microscopic model based on BCS quasiparticles within the Nilsson level scheme. This model also gives information about the parity distribution and the number of broken Cooper pairs as a function of excitation energy. The experimental gamma-ray strength functions are compared to theoretical models of the E1, M1, and E2 strength, and to data from (gamma,n) and (gamma,p) experiments. The strength functions show an enhancement at low gamma energies that cannot be explained by the present, standard models.

  15. Concentration of actinides in the food chain

    Considerable concern is now being expressed over the discharge of actinides into the environment. This report presents a brief review of the chemistry of the actinides and examines the evidence for interaction of the actinides with some naturally-occurring chelating agents and other factors which might stimulate actinide concentration in the food chain of man. This report also reviews the evidence for concentration of actinides in plants and for uptake through the gastrointestinal tract. (author)

  16. Calorimetric assay of minor actinides

    Rudy, C.; Bracken, D.; Cremers, T.; Foster, L.A.; Ensslin, N.

    1996-12-31

    This paper reviews the principles of calorimetric assay and evaluates its potential application to the minor actinides (U-232-4, Am-241, Am- 243, Cm-245, Np-237). We conclude that calorimetry and high- resolution gamma-ray isotopic analysis can be used for the assay of minor actinides by adapting existing methodologies for Pu/Am-241 mixtures. In some cases, mixtures of special nuclear materials and minor actinides may require the development of new methodologies that involve a combination of destructive and nondestructive assay techniques.

  17. Calorimetric assay of minor actinides

    This paper reviews the principles of calorimetric assay and evaluates its potential application to the minor actinides (U-232-4, Am-241, Am- 243, Cm-245, Np-237). We conclude that calorimetry and high- resolution gamma-ray isotopic analysis can be used for the assay of minor actinides by adapting existing methodologies for Pu/Am-241 mixtures. In some cases, mixtures of special nuclear materials and minor actinides may require the development of new methodologies that involve a combination of destructive and nondestructive assay techniques

  18. Level Densities and Radiative Strength Functions in 56FE and 57FE

    Tavukcu, E

    2002-12-10

    Understanding nuclear level densities and radiative strength functions is important for pure and applied nuclear physics. Recently, the Oslo Cyclotron Group has developed an experimental method to extract level densities and radiative strength functions simultaneously from the primary {gamma} rays after a light-ion reaction. A primary {gamma}-ray spectrum represents the {gamma}-decay probability distribution. The Oslo method is based on the Axel-Brink hypothesis, according to which the primary {gamma}-ray spectrum is proportional to the product of the level density at the final energy and the radiative strength function. The level density and the radiative strength function are fit to the experimental primary {gamma}-ray spectra, and then normalized to known data. The method works well for heavy nuclei. The present measurements extend the Oslo method to the lighter mass nuclei {sup 56}Fe and {sup 57}Fe. The experimental level densities in {sup 56}Fe and {sup 57}Fe reveal step structure. This step structure is a signature for nucleon pair breaking. The predicted pairing gap parameter is in good agreement with the step corresponding to the first pair breaking. Thermodynamic quantities for {sup 56}Fe and {sup 57}Fe are derived within the microcanonical and canonical ensembles using the experimental level densities. Energy-temperature relations are considered using caloric curves and probability density functions. The differences between the thermodynamics of small and large systems are emphasized. The experimental heat capacities are compared with the recent theoretical calculations obtained in the Shell Model Monte Carlo method. Radiative strength functions in {sup 56}Fe and {sup 57}Fe have surprisingly high values at low {gamma}-ray energies. This behavior has not been observed for heavy nuclei, but has been observed in other light- and medium-mass nuclei. The origin of this low {gamma}-ray energy effect remains unknown.

  19. Correlation of vitamin D, bone mineral density and parathyroid hormone levels in adults with low bone density

    Sunil Kota

    2013-01-01

    Full Text Available Background: Bone mineral densiy (BMD is known to be affected by serum 25-hydroxyvitamin D (25(OH D levels, intact parathyroid hormone (iPTH levels. Indian data pertinent to above observation is scant. Our study aimed to investigate the relationships between serum 25-hydroxyvitamin D (25(OH D levels, intact parathyroid hormone (iPTH levels and bone mineral density (BMD in a cohort of Indian patients. Materials and Methods: Adults with or without fragility fractures with low BMD at the hip or lumbar spine were evaluated clinically along with laboratory investigations. T-scores of the hip and spine were derived from BMD-DEXA (dual-energy X-ray absorptiometry. Multivariate regression models were used to investigate the relationships between serum 25(OH D, iPTH and BMD. Results: Total of 102 patients (male:female = 38:64 with a mean age of 62.5 ± 6.4 years were included in the study. Forty-four patients had osteopenia. Osteoporosis was present in 58 patients. The mean values for serum 25(OH D and iPTH levels were 21.3 ± 0.5 ng/ml and 53.1 ± 22.3 pg/ml, respectively. In 84.3% of patients, serum 25(OH D levels were below 30 ng/ml (Normal = 30-74 ng/ml, confirming vitamin D deficiency. There was no association between 25(OH D levels and BMD at the hip or lumbar spine (P = 0.473 and 0.353, respectively. Both at the hip and lumbar spine; iPTH levels, male gender, body mass index (BMI and age were found to be significant predictors of BMD. Patients with higher BMI had significantly lower BMD and T-score. At levels <30 ng/ml, 25(OH D was negatively associated with iPTH (P = 0.041. Conclusion: Among our cohort of patients with low BMD, no direct relationship between serum 25(OH D levels and BMD was observed. However, a negative correlation between iPTH and 25(OH D at serum 25(OH D concentrations <30 ng/ml. Serum iPTH levels showed a significant negative association with BMD at the hip and lumbar spine. Our findings underscore the critical role of

  20. Actinides and the environment

    The book combines in one volume the opinions of experts regarding the interaction of radionuclides with the environment and possible ways to immobilize and dispose of nuclear waste. The relevant areas span the spectrum from pure science, such as the fundamental physics and chemistry of the actinides, geology, environmental transport mechanisms, to engineering issues such as reactor operation and the design of nuclear waste repositories. The cross-fertilization between these various areas means that the material in the book will be accessible to seasoned scientists who may wish to obtain an overview of the current state of the art in the field of environmental remediation of radionuclides, as well as to beginning scientists embarking on a career in this field. refs

  1. Calculated Bulk Properties of the Actinide Metals

    Skriver, Hans Lomholt; Andersen, O. K.; Johansson, B.

    1978-01-01

    Self-consistent relativistic calculations of the electronic properties for seven actinides (Ac-Am) have been performed using the linear muffin-tin orbitals method within the atomic-sphere approximation. Exchange and correlation were included in the local spin-density scheme. The theory explains t...... the variation of the atomic volume and the bulk modulus through the 5f series in terms of an increasing 5f binding up to plutonium followed by a sudden localisation (through complete spin polarisation) in americium...

  2. Population-Level Density Dependence Influences the Origin and Maintenance of Parental Care

    Reyes, Elijah; Thrasher, Patsy; Bonsall, Michael B.; Klug, Hope

    2016-01-01

    Parental care is a defining feature of animal breeding systems. We now know that both basic life-history characteristics and ecological factors influence the evolution of care. However, relatively little is known about how these factors interact to influence the origin and maintenance of care. Here, we expand upon previous work and explore the relationship between basic life-history characteristics (stage-specific rates of mortality and maturation) and the fitness benefits associated with the origin and the maintenance of parental care for two broad ecological scenarios: the scenario in which egg survival is density dependent and the case in which adult survival is density dependent. Our findings suggest that high offspring need is likely critical in driving the origin, but not the maintenance, of parental care regardless of whether density dependence acts on egg or adult survival. In general, parental care is more likely to result in greater fitness benefits when baseline adult mortality is low if 1) egg survival is density dependent or 2) adult mortality is density dependent and mutant density is relatively high. When density dependence acts on egg mortality, low rates of egg maturation and high egg densities are less likely to lead to strong fitness benefits of care. However, when density dependence acts on adult mortality, high levels of egg maturation and increasing adult densities are less likely to maintain care. Juvenile survival has relatively little, if any, effect on the origin and maintenance of egg-only care. More generally, our results suggest that the evolution of parental care will be influenced by an organism’s entire life history characteristics, the stage at which density dependence acts, and whether care is originating or being maintained. PMID:27093056

  3. Population-Level Density Dependence Influences the Origin and Maintenance of Parental Care.

    Reyes, Elijah; Thrasher, Patsy; Bonsall, Michael B; Klug, Hope

    2016-01-01

    Parental care is a defining feature of animal breeding systems. We now know that both basic life-history characteristics and ecological factors influence the evolution of care. However, relatively little is known about how these factors interact to influence the origin and maintenance of care. Here, we expand upon previous work and explore the relationship between basic life-history characteristics (stage-specific rates of mortality and maturation) and the fitness benefits associated with the origin and the maintenance of parental care for two broad ecological scenarios: the scenario in which egg survival is density dependent and the case in which adult survival is density dependent. Our findings suggest that high offspring need is likely critical in driving the origin, but not the maintenance, of parental care regardless of whether density dependence acts on egg or adult survival. In general, parental care is more likely to result in greater fitness benefits when baseline adult mortality is low if 1) egg survival is density dependent or 2) adult mortality is density dependent and mutant density is relatively high. When density dependence acts on egg mortality, low rates of egg maturation and high egg densities are less likely to lead to strong fitness benefits of care. However, when density dependence acts on adult mortality, high levels of egg maturation and increasing adult densities are less likely to maintain care. Juvenile survival has relatively little, if any, effect on the origin and maintenance of egg-only care. More generally, our results suggest that the evolution of parental care will be influenced by an organism's entire life history characteristics, the stage at which density dependence acts, and whether care is originating or being maintained. PMID:27093056

  4. A theoretical study of actinide and lanthanide extraction with carbamoylmethylphosphine oxide ligands

    With the development of nuclear energy, safe disposal of the spent nuclear fuel especially high level liquid waste (HLLW) generated during the PUREX (Plutonium Uranium Extraction) process has become the key factors affecting the sustainable development of nuclear energy. The n-octyl(phenyl)-N,N-diisobutylmethylcarbamoyl phosphine oxide (CMPO) used in the so-called TRUEX (Transuranium Extraction) process was found to possess excellent extracting ability for actinide and lanthanide cations in acidic media. In this work, The UO22+, NpO2+, Pu4+, Am3+ and Eu3+ extraction complexes with CMPO and diphenyl-N,N-diisobutyl carbamoyl phosphine oxide (Ph2CMPO) have been investigated by density functional theory (DFT) in conjunction with relativistic small-core pseudopotentials. For most extraction complexes, the CMPO and Ph2CMPO molecules are coordinated as bidentate chelating ligands through the carbonyl oxygen and phosphoric oxygen atoms. The metal-ligand bonding is mainly ionic for all of these complexes. The neutral UO2L2(NO3)2, NpO2L2(NO3), PuL2(NO3)4, AmL3(NO3)3 and EuL3(NO3)3 complexes are predicted to be the most thermodynamically stable molecules according to the metal-ligand complexation reactions. As reported in the literature, the extractability of these actinides decrease in the order of Pu4+ > UO22+ > Eu3+ ≈ Am3+ > NpO2+. In addition, hydration energies may play an important role in the extractability of CMPO and Ph2CMPO for these actinide ions. In most cases, the complexes with CMPO and Ph2CMPO ligands have comparable metal-ligand binding energies, i.e., the substitution of a phenyl ring for the n-octyl at the phosphoryl group of CMPO has little influence on the extraction of these actinides and lanthanides. (author)

  5. Particle-hole state densities with non-equidistant single-particle levels

    Harangozo, A; Avrigeanu, M; Avrigeanu, V

    1998-01-01

    The correct use of energy-dependent single-particle level (s.p.l.) densities within particle-hole state densities based on the equidistant spacing model (ESM) is analysed. First, an analytical expression is obtained following the convolution of energy-dependent excited-particle and hole densities. Next, a comparison is made with results of the ESM formula using average s.p.l. densities for the excited particles and holes, respectively. The Fermi-gas model (FGM) s.p.l. densities calculated at the corresponding average excitation energies are used in both cases. The analysis concerns also the density of particle-hole bound states. The pairing correlations are taken into account while the comparison of various effects includes the exact correction for the Pauli exclusion principle. Quantum-mechanical s.p.l. densities and the continuum effect can also match a corresponding FGM formula, suitable for use within the average energy-dependent partial state density in multistep reaction models.

  6. Nuclear level density as a tool for probing the inelastic scattering of 6He

    Canbula, Bora

    2014-01-01

    The cross sections are calculated for the both elastic and inelastic scattering of 6He from 12C and 4He. A phenomenological optical potential is used to describe the elastic scattering. 4He is taken as spherical and inelastic couplings to the first excited states of 6He and 12C are described with collective rotational model and coupled-channels method. Deformation lengths for 6He and 12C are determined from semi-classical nuclear level density model by using Laplace-like formula for the nuclear level density parameter. The comparison of the predicted and the measured cross sections are presented to test the applicability of nuclear level density model to the light exotic nuclei reactions. Good agreement is achieved between the predicted and measured cross sections.

  7. Level densities of heavy nuclei in the shell model Monte Carlo approach

    Alhassid, Y.; Bertsch, G. F.; Gilbreth, C. N.; Nakada, H.; Özen, C.

    2016-06-01

    Nuclear level densities are necessary input to the Hauser-Feshbach theory of compound nuclear reactions. However, the microscopic calculation of level densities in the presence of correlations is a challenging many-body problem. The configurationinteraction shell model provides a suitable framework for the inclusion of correlations and shell effects, but the large dimensionality of the many-particle model space has limited its application in heavy nuclei. The shell model Monte Carlo method enables calculations in spaces that are many orders of magnitude larger than spaces that can be treated by conventional diagonalization methods and has proven to be a powerful tool in the microscopic calculation of level densities. We discuss recent applications of the method in heavy nuclei.

  8. Evaluation of Phonon-level Density of UO2 by Molecular Dynamics Simulation

    Hui-fen Zhang; Gan Li; Xiao-feng Tian; Tao Gao

    2011-01-01

    Molecular dynamics calculation of UO2 in a wide temperature range are presented and discussed.The calculated lattice parameters,mean square displacements,and dynamic property of phonon-level density of the velocity auto-correlation functions for UO2 are provided.The Morelon potential and the Basak potential are employed.It confirms that the calculated lattice parameters using the Basak potential are in nearly perfect agreement with the reported values.The models successfully predict mean square displacement and Bredig transition.Furthermore,the phonon-level density of uranium dioxide are discussed.The intensity of phonon-level density increases with temperature,and the properties of UO2 are characterized by large thermal vibrations rather than extensive disorder.

  9. Environmental research on actinide elements

    The papers synthesize the results of research sponsored by DOE's Office of Health and Environmental Research on the behavior of transuranic and actinide elements in the environment. Separate abstracts have been prepared for the 21 individual papers

  10. Analysis of optical properties of actinide dioxides

    Ionic calculations, symmetry considerations, and detailed analysis of reflectivity experiments have been used to identify general features of the band structure of actinide dioxides with a fluorite lattice. The ionic calculations adjust atomic energy levels by the electrostatic energies arising from long range electric fields of the ionic lattice; the labelling of high lying energy bands is determined by symmetry; experimental analysis includes the use of appropriate sum rules. A combination of these considerations enable a tentative band scheme to be constructed. It is suggested that there are filled valence bands (GAMMA15,GAMMA'25) originating in oxygen 2p-states and empty conduction bands (GAMMA1,GAMMA12,GAMMA'25) originating in actinide 7s and 6d states. The mean band gap (Penn gap) is of the order of 14 eV. The actinide f-electron states, which lie approximately 5 eV below the conduction bands, are taken to be localized - at least in UO2. (author)

  11. BWR Assembly Optimization for Minor Actinide Recycling

    The Primary objective of the proposed project is to apply and extend the latest advancements in LWR fuel management optimization to the design of advanced boiling water reactor (BWR) fuel assemblies specifically for the recycling of minor actinides (MAs). A top-level objective of the Advanced Fuel Cycle Systems Analysis program element of the DOE NERI program is to investigate spent fuel treatment and recycling options for current light water reactors (LWRs). Accordingly, this project targets to expand the traditional scope of nuclear fuel management optimization into the following two complementary specific objectives: (1) To develop a direct coupling between the pin-by-pin within-bundle loading control variables and core-wide (bundle-by-bundle) optimization objectives, (2) to extend the methodology developed to explicitly encompass control variables, objectives, and constraints designed to maximize minor actinide incineration in BWR bundles and cycles. The first specific objective is projected to 'uncover' dormant thermal margin made available by employing additional degrees of freedom within the optimization process, while the addition of minor actinides is expected to 'consume' some of the uncovered thermal margin. Therefore, a key underlying goal of this project is to effectively invest some of the uncovered thermal margin into achieving the primary objective.

  12. Properties of minor actinide nitrides

    The present status of the research on properties of minor actinide nitrides for the development of an advanced nuclear fuel cycle based on nitride fuel and pyrochemical reprocessing is described. Some thermal stabilities of Am-based nitrides such as AmN and (Am, Zr)N were mainly investigated. Stabilization effect of ZrN was cleary confirmed for the vaporization and hydrolytic behaviors. New experimental equipments for measuring thermal properties of minor actinide nitrides were also introduced. (author)

  13. A 90 minute soccer match decreases triglyceride and low density lipoprotein but not high-density lipoprotein and cholesterol levels

    Nader - Rahnama

    2009-11-01

    Full Text Available

    • BACKGROUND: The association between the lipid profiles level and the incidence and severity of coronary heart disease (CHD is very pronounced in epidemiological studies, and an inverse relation between physical fitness and the incidence of coronary heart disease has been observed in many studies. The aim of this study was to investigate the impact of a soccer match on lipid parameters of professional soccer players.
    • METHODS: Twenty two professional soccer players participated in the study. Blood (10ml for determination of lipid profiles was obtained at rest and immediately after a 90 minute soccer match. Lipid parameters were measured using Boehringer Mannheim kits and Clinilab and BioMerieux analyser.
    • RESULTS: The results of this study showed that the triglyceride was significantly higher before the match than afterwards (159.09 ± 58.2 vs. 88.63 ± 34.1 mg/dl, p < 0.001, whereas the low-density lipoprotein (LDL was lower before the match than after it (98.04 ± 28.9 vs. 112.31 ± 30.5 mg/dl. Moreover, there were no significant differences in cholesterol concentration (171.4 ± 30.28 mg/dl vs. 173.18 ± 32.75 mg/dl and high-density lipoprotein (HDL concentration (34.04 ± 5.58 mg/dl vs. 34.4 ± 4.6 mg/dl between before and after the match.
    • CONCLUSIONS: Although the soccer competitive match has no favourable acute effect on lipid

    • Decreased high-density lipoprotein cholesterol levels in polyarticular juvenile idiopathic arthritis

      Roberta Gonçalves Marangoni

      2011-01-01

      Full Text Available OBJECTIVES: To investigate the prevalence of dyslipoproteinemia in a homogeneous cohort of polyarticular juvenile idiopathic arthritis patients. METHODS: Based on the National Cholesterol Education Program, fasting lipoprotein levels and risk levels for coronary artery disease were determined in 28 patients with polyarticular juvenile idiopathic arthritis. The exclusion criteria included diabetes, thyroid dysfunction, smoking, proteinuria, lipid-lowering drugs, and hormone/diuretic therapy. Disease activity, disease duration, and therapy with corticosteroids and/or chloroquine were defined at the time of lipid measurements. RESULTS: Dyslipoproteinemia was identified in 20 of the 28 (71% patients with polyarticular juvenile idiopathic arthritis. The primary lipoprotein risk factor was decreased high-density lipoprotein cholesterol (57%, followed by elevated levels of low-density lipoprotein cholesterol (18%, triglycerides (14%, and total cholesterol (7%. The male patients had decreased high-density lipoprotein cholesterol levels than the female patients (p5 years disease duration. CONCLUSIONS: Dyslipoproteinemia is highly prevalent in patients with polyarticular juvenile idiopathic arthritis and is primarily related to decreased high-density lipoprotein cholesterol levels; therefore, early intervention is essential.

    • Rapid determination of alpha emitters using Actinide resin.

      Navarro, N; Rodriguez, L; Alvarez, A; Sancho, C

      2004-01-01

      The European Commission has recently published the recommended radiological protection criteria for the clearance of building and building rubble from the dismantling of nuclear installations. Radionuclide specific clearance levels for actinides are very low (between 0.1 and 1 Bq g(-1)). The prevalence of natural radionuclides in rubble materials makes the verification of these levels by direct alpha counting impossible. The capability of Actinide resin (Eichrom Industries, Inc.) for extracting plutonium and americium from rubble samples has been tested in this work. Besides a strong affinity for actinides in the tri, tetra and hexavalent oxidation states, this extraction chromatographic resin presents an easy recovery of absorbed radionuclides. The retention capability was evaluated on rubble samples spiked with certified radionuclide standards (239Pu and 241Am). Samples were leached with nitric acid, passed through a chromatographic column containing the resin and the elution fraction was measured by LSC. Actinide retention varies from 60% to 80%. Based on these results, a rapid method for the verification of clearance levels for actinides in rubble samples is proposed. PMID:15177360

    • Production and measurement of minor actinides in the commercial fuel cycle

      Stanbro, W.D. [comp.

      1997-03-01

      The minor actinide elements, particularly neptunium and americium, are produced as a normal byproduct of the operation of thermal power reactors. Because of the existence of long-lived isotopes of these elements, they constitute the major sources of the residual radiation in spent fuel or in wastes resulting from reprocessing. This has led to examinations by some countries of the possibility of separating the minor actinides from waste products. The papers found in this report address the production of minor actinides in common thermal power reactors as well as approaches to measure these materials in various media. The first paper in this volume, {open_quotes}Production of Minor Actinides in the Commercial Fuel Cycle,{close_quotes} uses calculations with the ORIGEN2 reactor and decay code to estimate the amounts of minor actinides in spent fuel and separated plutonium as a function of reactor irradiation and the time after discharge. The second paper, {open_quotes}Destructive Assay of Minor Actinides,{close_quotes} describes a number of promising approaches for the chemical analysis of minor actinides in the various forms in which they are found at reprocessing plants. The next paper, {open_quotes}Hybrid KED/XRF Measurement of Minor Actinides in Reprocessing Plants,{close_quotes} uses the results of a simulation model to examine the possible applications of the hybrid KED/XRF instrument to the determination of minor actinides in some of the solutions found in reprocessing plants. In {open_quotes}Calorimetric Assay of Minor Actinides,{close_quotes} the authors show some possible extensions of this powerful technique beyond the normal plutonium assays to include the minor actinides. Finally, the last paper in this volume, {open_quotes}Environment Measurements of Transuranic Nuclides,{close_quotes} discusses what is known about the levels of the minor actinides in the environment and ways to analyze for these materials in environmental matrices.

    • Orbital-unrelaxed Lagrangian density matrices for periodic systems at the local MP2 level

      Usvyat, D; Schuetz, M [Institute of Physical and Theoretical Chemistry, University of Regensburg, Universitaetsstrasse 31, D-93040 Regensburg (Germany)], E-mail: denis.usvyat@chemie.uni-regensburg.de, E-mail: martin.schuetz@chemie.uni-regensburg.de

      2008-06-01

      In the present paper a method based on the Hylleraas functional is proposed in order to obtain correlated ground state density matrices for periodic systems at the level of local MP2. The general properties of these density matrices, namely size-extensivity, translational invariance, exponential decay of the off-diagonal elements, etc are discussed. As test examples we investigate the influence of the electron correlation on the density in diamond and strontium titanate (in the latter case via the Mulliken charges). The calculations reveal that in diamond the concentration of the electrons in the bond region decreases when the correlation is taken into account, but the change in the density relative to Hartree-Fock is small. In the case of SrTiO{sub 3}, this change is more significant and causes a lowering of the ionicity of this crystal.

    • Orbital-unrelaxed Lagrangian density matrices for periodic systems at the local MP2 level

      In the present paper a method based on the Hylleraas functional is proposed in order to obtain correlated ground state density matrices for periodic systems at the level of local MP2. The general properties of these density matrices, namely size-extensivity, translational invariance, exponential decay of the off-diagonal elements, etc are discussed. As test examples we investigate the influence of the electron correlation on the density in diamond and strontium titanate (in the latter case via the Mulliken charges). The calculations reveal that in diamond the concentration of the electrons in the bond region decreases when the correlation is taken into account, but the change in the density relative to Hartree-Fock is small. In the case of SrTiO3, this change is more significant and causes a lowering of the ionicity of this crystal

    • Characteristics of High-density Lipoprotein Subclasses Distribution for Subjects with Desirable Total Cholesterol Levels

      Xu Yanhua; Liu Yinghui; Fu Mingde; Long Shiyin; Tian Li; Jia Lianqun

      2011-01-01

      Abstract Background To investigate alteration of high density lipoproteins (HDL) subclasses distribution in different total cholesterol (TC) levels, mainly the characteristics of HDL subclasses distribution in desirable TC levels and analyze the related mechanisms. Methods ApoA-I contents of plasma HDL subclasses were determined by 2-dimensional gel electrophoresis coupled with immunodetection. 486 Chinese Adults subjects were assigned to different TC groups according to the third Report of N...

    • MOLECULAR SPECTROSCPY AND REACTIONS OF ACTINIDES IN THE GAS PHASE AND CRYOGENIC MATRICES

      Heaven, Michael C.; Gibson, John K.; Marcalo, Joaquim

      2009-02-01

      In this chapter we review the spectroscopic data for actinide molecules and the reaction dynamics for atomic and molecular actinides that have been examined in the gas phase or in inert cryogenic matrices. The motivation for this type of investigation is that physical properties and reactions can be studied in the absence of external perturbations (gas phase) or under minimally perturbing conditions (cryogenic matrices). This information can be compared directly with the results from high-level theoretical models. The interplay between experiment and theory is critically important for advancing our understanding of actinide chemistry. For example, elucidation of the role of the 5f electrons in bonding and reactivity can only be achieved through the application of experimentally verified theoretical models. Theoretical calculations for the actinides are challenging due the large numbers of electrons that must be treated explicitly and the presence of strong relativistic effects. This topic has been reviewed in depth in Chapter 17 of this series. One of the goals of the experimental work described in this chapter has been to provide benchmark data that can be used to evaluate both empirical and ab initio theoretical models. While gas-phase data are the most suitable for comparison with theoretical calculations, there are technical difficulties entailed in generating workable densities of gas-phase actinide molecules that have limited the range of species that have been characterized. Many of the compounds of interest are refractory, and problems associated with the use of high temperature vapors have complicated measurements of spectra, ionization energies, and reactions. One approach that has proved to be especially valuable in overcoming this difficulty has been the use of pulsed laser ablation to generate plumes of vapor from refractory actinide-containing materials. The vapor is entrained in an inert gas, which can be used to cool the actinide species to room

  1. Theory of gravity admitting arbitrary choice of the energy density level

    Cherkas, S L

    2016-01-01

    We suggest a five-vectors theory of gravity admitting arbitrary choice of the energy density level. This theory is formulated as the constraint theory of the second kind, where the concrete values of Lagrange multipliers are evaluated. Cosmological implications of the model could be that the residual vacuum fluctuations dominate over all the universe evolution that resembles the Milne's universe.

  2. Effects of shape differences in the level densities of three formalisms on calculated cross-sections

    Effects of shape differences in the level densities of three formalisms on calculated cross-sections and particle emission spectra are described. Reactions for incident neutrons up to 20 MeV on 58Ni are chosen for illustrations. Level density parameters for one of the formalisms are determined from the available neutron resonance data for one residual nuclide in the binary channels and from fitting the measured (n,n'), (n,p) and (n,α) cross-sections for the other two residual nuclides. Level density parameters for the other two formalisms are determined such that they yield the same values as the above one at two selected energies. This procedure forces the level densities from the three formalisms used for the binary pat of the calculation to be as close as possible. The remaining differences are in their energy dependences (shapes). It is shown that these shape differences alone are enough to cause the calculated cross-sections and particle emission spectra to be different by up to 60%. (author)

  3. Effects of shape differences in the level densities of three formalisms of calculated cross sections

    Effects of shape differences in the level densities of three formalisms on calculated cross sections and particle emission spectra are described. Reactions for incident neutrons up to 20 MeV on 58Ni are chosen for illustrations. Level-density parameters for one of the formalisms are determined from the available neutron resonance data for one residual nuclide in the binary channels and from fitting the measured (n, n'), (n, p), and (n, α) cross sections for the other two residual nuclides. Level-density parameters for the other two formalisms are determined such that they yield the same values as the above one at two selected energies. This procedure forces the level densities from the three formalisms used for the binary part of the calculation to be as close as possible. The remaining differences are in their energy dependences (shapes). It is shown that these shape differences alone are enough to cause the calculated cross sections and particle emission spectra to be different by up to 60%

  4. Separation of trivalent actinides and lanthanides from simulated high-level waste using cobalt bis(dicarbollide) (1{sup -}) ion derivate substituted with diphenyl-N-tert.octyl-carbamoylmethylphosphine oxide

    Selucky, P.; Lucanikova, M. [Nuclear Research Institute, Rez near Prague (Czech Republic); Gruener, B. [Academy of Sciences of the Czech Republic, Rez near Prague (Czech Republic). Inst. of Inorganic Chemistry

    2012-07-01

    A derivative with cobalt bis(dicarbollide)(1{sup -}) ion covalently bonded with diphenyl-N-tert.octyl-carbamoylmethylphosphine oxide with a formula [(8-Ph{sub 2}P(O))-CH{sub 2}C(O)N-t-C{sub 8}H{sub 17}-(CH{sub 2}-CH{sub 2}O){sub 2}-(1,2-C{sub 2}B{sub 9}H{sub 10})(1',2'-C{sub 2}B{sub 9}H{sub 11})-3,3'-Co]{sup -} (CMPO-COSAN) has been evaluated for actinides(III)/lanthanides(III) separation from high level liquid waste (HLLW) from PUREX reprocessing. The procedures for HLLW treatment by CMPO-COSAN dissolved in low polar mixture of hexylmethylketone and hydrogenated tetrapropylene (HMK/TPH, 1:1) or polar mixture of nitrobenzene/bromoform (NB/BF, 9:1) were proposed. The good separation of Am(III)/Ln(III) from bulk of fission products was achieved. The trivalent radionuclides were effectively stripped from the loaded organic phase by using ammonium citrate or mixture of ammonium citrate and ammonium diethylenetriamine pentaacetate (DTPA). The co-extraction of some undesirable elements as Zr, Mo, Pd was suppressed using oxalic acid and HEDTA in extraction and a scrub steps. However, co-extraction of Ag has to be solved, yet. (orig.)

  5. THERMODYNAMICS OF THE ACTINIDES

    Cunningham, Burris B.

    1962-04-01

    Recent work on the thermodynamic properties of the transplutonium elements is presented and discussed in relation to trends in thermodynamic properties of the actinide series. Accurate values are given for room temperature lattice parameters of two crystallographic forms, (facecentred cubic) fcc and dhcp (double-hexagonal closepacked), of americium metal and for the coefficients of thermal expansion between 157 and 878 deg K (dhcp) and 295 to 633 deg K (fcc). The meiting point of the metal, and its magnetic susceptibility between 77 and 823 deg K are reported and the latter compared with theoretical values for the tripositive ion calculated from spectroscopic data. Similar data (crystallography, meiting point and magnetic susceptibility) are given for metallic curium. A value for the heat of formation of americium monoxide is reported in conjunction with crystallographic data on the monoxide and mononitride. A revision is made in the current value for the heat of formation of Am/O/sub 2/ and for the potential of the Am(III)-Am(IV) couple. The crystal structures and lattice parameters are reported for the trichloride, oxychloride and oxides of californium. (auth)

  6. On angular momentum and parity dependence of nuclear level densities in a simple random sampling approach

    Based on simple random sampling (SRS), we propose a Monte Carlo method for the faster computation of the smoothed part of the density of nuclear states. To test the applicability of the SRS approach we study in this framework the excitation energy (E), angular momentum (J) and parity dependence of nuclear level densities for an independent particle system. As an illustrative example, we consider a pf-shell nucleus, 48Cr. It is found that the values of a few lower order moments for the state density I(E) calculated using SRS and combinatorial (or direct counting) methods are almost the same and a locally smoothed part of the state density can be constructed using these moments in a univariate Edgeworth expansion. We calculate the energy dependent spin-cutoff factor and parity asymmetry and find that for both cases the SRS approach works quite well. We use the SRS moments to construct different forms of the bivariate distribution for I(E,M) (M is the z-component of J) namely (a) a bivariate Edgeworth expansion, (b) a product of the univariate Edgeworth expansion (I(E)) and a Gaussian form for conditional M distribution I(M vertical stroke E) and (c) a product of the univariate Edgeworth expansions for both I(E) and I(M vertical stroke E) and compare the resulting fixed-J level density Il(E,J) with the corresponding combinatorial results. (orig.)

  7. Actinides in irradiated graphite of RBMK-1500 reactor

    Highlights: • Activation of actinides in the graphite of the RBMK-1500 reactor was analyzed. • Numerical modeling using SCALE 6.1 and MCNPX was used for actinide calculation. • Measurements of the irradiated graphite sample were used for model validation. • Results are important for further decommissioning process of the RBMK type reactors. - Abstract: The activation of graphite in the nuclear power plants is the problem of high importance related with later graphite reprocessing or disposal. The activation of actinide impurities in graphite due to their toxicity determines a particular long term risk to waste management. In this work the activation of actinides in the graphite constructions of the RBMK-1500 reactor is determined by nuclear spectrometry measurements of the irradiated graphite sample from the Ignalina NPP Unit I and by means of numerical modeling using two independent codes SCALE 6.1 (using TRITON-VI sequence) and MCNPX (v2.7 with CINDER). Both models take into account the 3D RBMK-1500 reactor core fragment with explicit graphite construction including a stack and a sleeve but with a different simplification level concerning surrounding graphite and construction of control roads. The verification of the model has been performed by comparing calculated and measured isotope ratios of actinides. Also good prediction capabilities of the actinide activation in the irradiated graphite have been found for both calculation approaches. The initial U impurity concentration in the graphite model has been adjusted taking into account the experimental results. The specific activities of actinides in the irradiated RBMK-1500 graphite constructions have been obtained and differences between numerical simulation results, different structural parts (sleeve and stack) as well as comparison with previous results (Ancius et al., 2005) have been discussed. The obtained results are important for further decommissioning process of the Ignalina NPP and other RBMK

  8. Systematic for parity distribution in nuclear level density near neutron separation energies

    The correct form of nuclear level density function ρ(U,J,π) is required to calculate nuclear cross-sections needed for various applications ranging from reactor designing, nuclear astrophysics, etc., to transmutation of nuclear waste. The asymmetrical statistical distribution of parity of nuclear levels at low energies poses an intriguing problem leading to larger uncertainties in the calculated values of cross-sections. On the basis of high resolution data available on individual resonance parameters (Eo,Jπ,Γn) for s- and p-wave neutrons, mass and energy dependence formulae for the parity distribution in the nuclear level density have been proposed which supports the fact of equipartition of parities at high excitation energies.

  9. Systematic for parity distribution in nuclear level density near neutron separation energies

    Singhal, S.K., E-mail: s_k_singhal@yahoo.co.u [Engineering Department, Ibra College of Technology, Ministry of Manpower (Oman); Agrawal, H.M. [Physics Department, G.B. Pant University of Agriculture and Technology, Pantnagar (India)

    2011-03-01

    The correct form of nuclear level density function {rho}(U,J,{pi}) is required to calculate nuclear cross-sections needed for various applications ranging from reactor designing, nuclear astrophysics, etc., to transmutation of nuclear waste. The asymmetrical statistical distribution of parity of nuclear levels at low energies poses an intriguing problem leading to larger uncertainties in the calculated values of cross-sections. On the basis of high resolution data available on individual resonance parameters (E{sub o},J{sup {pi},{Gamma}}{sub n}) for s- and p-wave neutrons, mass and energy dependence formulae for the parity distribution in the nuclear level density have been proposed which supports the fact of equipartition of parities at high excitation energies.

  10. On the relation between the statistical γ-decay and the level density in 162Dy

    The level density of low-spin states (0-10ℎ) in 162Dy has been determined from the ground state up to approximately 6 MeV of excitation energy. Levels in the excitation region up to 8 MeV were populated by means of the 163Dy(3He, α) reaction, and the first-generation γ-rays in the decay of these states has been isolated. The energy distribution of the first-generation γ-rays provides a new source of information about the nuclear level density over a wide energy region. A broad peak is observed in the first-generation spectra, and the authors suggest an interpretation in terms of enhanced M1 transitions between different high-j Nilsson orbitals. 30 refs., 9 figs., 2 tabs

  11. Generalized Freud’s equation and level densities with polynomial potential

    Akshat Boobna; Saugata Ghosh

    2013-08-01

    Orthogonal polynomials with weight exp[$−NV (x)$] are studied where $V (x) = \\sum_{k=1}^{d} a_{2k} x^{2k}$ is a polynomial of order 2. The generalized Freud’s equations for = 3, 4 and 5 are derived and using this $R_{} = h_{} / h{−1}$ is obtained, where $h_{}$ is the normalization constant for the corresponding orthogonal polynomials. Moments of the density functions, expressed in terms of $R_{}$ , are obtained using Freud’s equation and using this, explicit results of level densities as $N → ∞$ are derived using the method of resolvents. The results are compared with those using Dyson–Mehta method.

  12. The selective extraction of oxidized minor actinides: a possible route for the Actinex program

    In the SPIN programme, defined by CEA to improve the management of high level nuclear waste, a part called ACTINEX is specially devoted to the extraction of long-lived alpha emitters and fission products from high level liquid waste issuing from the PUREX process. Concerning the actinides elements, as U and Pu are already recovered, the main objective to reach is now the quantitative extraction of Np and Am. The transmutation of these recovered actinides into short-lived radionuclides is then forecast. This paper deals with the possibilities to define a minor actinides partitioning process based on the selective extraction of actinides oxidized to their oxidation states higher than three. It essentially focuses on americium chemistry. Finally, two general separation scheme for minor actinide partitioning are proposed and discussed. (authors). 5 figs., 13 refs

  13. Kinetics of actinide complexation reactions

    Though the literature records extensive compilations of the thermodynamics of actinide complexation reactions, the kinetics of complex formation and dissociation reactions of actinide ions in aqueous solutions have not been extensively investigated. In light of the central role played by such reactions in actinide process and environmental chemistry, this situation is somewhat surprising. The authors report herein a summary of what is known about actinide complexation kinetics. The systems include actinide ions in the four principal oxidation states (III, IV, V, and VI) and complex formation and dissociation rates with both simple and complex ligands. Most of the work reported was conducted in acidic media, but a few address reactions in neutral and alkaline solutions. Complex formation reactions tend in general to be rapid, accessible only to rapid-scan and equilibrium perturbation techniques. Complex dissociation reactions exhibit a wider range of rates and are generally more accessible using standard analytical methods. Literature results are described and correlated with the known properties of the individual ions

  14. 33rd Actinide Separations Conference

    McDonald, L M; Wilk, P A

    2009-05-04

    Welcome to the 33rd Actinide Separations Conference hosted this year by the Lawrence Livermore National Laboratory. This annual conference is centered on the idea of networking and communication with scientists from throughout the United States, Britain, France and Japan who have expertise in nuclear material processing. This conference forum provides an excellent opportunity for bringing together experts in the fields of chemistry, nuclear and chemical engineering, and actinide processing to present and discuss experiences, research results, testing and application of actinide separation processes. The exchange of information that will take place between you, and other subject matter experts from around the nation and across the international boundaries, is a critical tool to assist in solving both national and international problems associated with the processing of nuclear materials used for both defense and energy purposes, as well as for the safe disposition of excess nuclear material. Granlibakken is a dedicated conference facility and training campus that is set up to provide the venue that supports communication between scientists and engineers attending the 33rd Actinide Separations Conference. We believe that you will find that Granlibakken and the Lake Tahoe views provide an atmosphere that is stimulating for fruitful discussions between participants from both government and private industry. We thank the Lawrence Livermore National Laboratory and the United States Department of Energy for their support of this conference. We especially thank you, the participants and subject matter experts, for your involvement in the 33rd Actinide Separations Conference.

  15. Actinide behavior under final repository relevant conditions

    Experiments on the solubility behavior and the redox chemistry of actinides and long-living fission products under different geochemical boundary conditions, here on the Np(V) solubility in alkaline CaCl2 systems, provide basic information on processes that can occur in a nuclear final repository in case of water ingress. The thermodynamic constants derived from these experiments allow the geochemical modeling of these processes and a rough estimation of radionuclide solubility limits for different scenarios. Scientific research projects on this issue will reduce the uncertainties of long-term safety analyses for final repositories for high-level radioactive wastes significantly.

  16. Potential radiation dose from eating fish exposed to actinide contamination

    Emery, R.M.; Klopfer, D.C.; Baker, D.A.; Soldat, J.K.

    1980-01-01

    The purpose of this work is to establish a maximum potential for transporting actinides to man via fish consumption. The study took place in U-Pond, a nuclear waste pond on the Hanford Site. It has concentrations of /sup 238/U, /sup 238/Pu, /sup 239,240/Pu and /sup 241/Am that are approximately three orders of magnitude greater than background levels. Fish living in the pond contain higher actinide concentrations than those observed in fish from any other location. Experiments were performed in U-pond to determine maximum quantities of actinides that could accumulate in fillets and whole bodies of two centrarchid fish species. Doses to hypothetical consumers were then estimated by assuming that actinide behavior in their bodies was similar to that defined for Standard Man by the International Commission on Radiological Protection. Results indicate that highest concentrations occurring in bluegill or bass muscle after more than a year's exposure to the pond would not be sufficient to produce a significant radiation dose to a human consumer, even if he ate 0.5 kg (approx.1 lb) of these fillets every day for 70 years. Natural predators (heron or coyote), having lifetime diets of whole fish from U-Pond, would receive less radiation dose from the ingested actinides than from natural background sources. 34 refs., 5 figs., 4 tabs.

  17. Potential radiation dose from eating fish exposed to actinide contamination

    The purpose of this work is to establish a maximum potential for transporting actinides to man via fish consumption. The study took place in U-Pond, a nuclear waste pond on the Hanford Site. It has concentrations of 238U, 238Pu, /sup 239,240/Pu and 241Am that are approximately three orders of magnitude greater than background levels. Fish living in the pond contain higher actinide concentrations than those observed in fish from any other location. Experiments were performed in U-pond to determine maximum quantities of actinides that could accumulate in fillets and whole bodies of two centrarchid fish species. Doses to hypothetical consumers were then estimated by assuming that actinide behavior in their bodies was similar to that defined for Standard Man by the International Commission on Radiological Protection. Results indicate that highest concentrations occurring in bluegill or bass muscle after more than a year's exposure to the pond would not be sufficient to produce a significant radiation dose to a human consumer, even if he ate 0.5 kg (∼1 lb) of these fillets every day for 70 years. Natural predators (heron or coyote), having lifetime diets of whole fish from U-Pond, would receive less radiation dose from the ingested actinides than from natural background sources. 34 refs., 5 figs., 4 tabs

  18. Study on the Extraction of Actinides From Simulated High-level Liquid Waste by Mixture of DHDECMP and TBP in Kerosene

    2001-01-01

    The distribution ratios of U(VI), Np(V), Pu(IV) and Am(III) are measured by the single stage extraction experiments of simulated high-level liquid waste with 22%DHDECMP-42%TBP/OK. The extraction behavior of U, Np, Pu and Am in simulated high-level liquid waste is determined on miniature countercurrent centrifugal contactor cascade (6 stages for extraction, 2 stages for scrubbing, 6 stages for stripping, AF : AX : AS=1 : 1.5 : 0.5; BF : BX=1 : 1). The experimental results show that removal efficiency of U(VI), Np(V), Pu(IV) and Am(III) from simulated high-level liquid waste, all of them ,is equal or more than 99.9%. The stripping efficiency of U(VI),

  19. INTERACTIVE EFFECT OF CAGE DENSITY AND DIETARY BLACK CUMIN LEVEL ON PRODUCTIVE EFFICIENCY IN BROILER CHICKENS

    L. D. Mahfudz

    2015-09-01

    Full Text Available The present research was aimed to evaluate an interactive effect of cage density and level ofdietary black cumin (BC on productive efficiency of broiler chickens. A total of 270 broiler chickens(initial body weight of 163.12 ± 8.10g were allocated into a completely randomized design with a 3 x 3factorial pattern. The first factor was the cage density (bird/m2 namely, D1 = 8; D2 = 10, and D3 = 12.The second factor was BC level (%, namely, B1 = 1; B2 = 2, and B3 = 3. Feed consumption, bodyweight gain (BWG, feed conversion ratio (FCR, protein digestibility, and income over feed cost(IOFC were the parameters measured. Data were subjected to ANOVA and continued to Duncan test.No interaction between cage density and black cumin on all parameters was observed. Feedconsumption and FCR were increased, but BWG was lowered significantly (P<0.05 due to the cagedensities of 10 and 12 birds/m2 on weeks 2 and 3. Protein digestibility was significantly increased byfeeding 2 and 3% BC. IOFC decreased significantly (P<0.05 when cage densities were 10 and 12birds/m2. In conclusion, the improvement of productive efficiency of broiler chicken reared at the cagedensity of 12 birds /m2 can be sufficiently achieved by feeding 1% black cumin.

  20. Fermi level pinning effects at gate-dielectric interfaces influenced by interface state densities

    洪文婷; 韩伟华; 吕奇峰; 王昊; 杨富华

    2015-01-01

    The dependences of Fermi-level pinning on interface state densities for the metal–dielectric, ploycrystalline silicon–dielectric, and metal silicide–dielectric interfaces are investigated by calculating their effective work functions and their pinning factors. The Fermi-level pinning factors and effective work functions of the metal–dielectric interface are observed to be more susceptible to the increasing interface state densities, differing significantly from that of the ploycrystalline silicon–dielectric interface and the metal silicide–dielectric interface. The calculation results indicate that metal silicide gates with high-temperature resistance and low resistivity are a more promising choice for the design of gate materials in metal-oxide semiconductor (MOS) technology.

  1. Complete inclusion of parity-dependent level densities in the statistical description of astrophysical reaction rates

    Loens, Hans Peter; Martínez-Pinedo, Gabriel; Rauscher, Thomas; Thielemann, Friedrich-Karl

    2008-01-01

    Microscopic calculations show a strong parity dependence of the nuclear level density at low excitation energy of a nucleus. Previously, this dependence has either been neglected or only implemented in the initial and final channels of Hauser-Feshbach calculations. We present an indirect way to account for a full parity dependence in all steps of a reaction, including the one of the compound nucleus formed in a reaction. To illustrate the impact on astrophysical reaction rates, we present rates for neutron captures in isotopic chains of Ni and Sn. Comparing with the standard assumption of equipartition of both parities, we find noticeable differences in the energy regime of astrophysical interest caused by the parity dependence of the nuclear level density found in the compound nucleus even at sizeable excitation energies.

  2. Actinide cation-cation complexes

    The +5 oxidation state of U, Np, Pu, and Am is a linear dioxo cation (AnO2+) with a formal charge of +1. These cations form complexes with a variety of other cations, including actinide cations. Other oxidation states of actinides do not form these cation-cation complexes with any cation other than AnO2+; therefore, cation-cation complexes indicate something unique about AnO2+ cations compared to actinide cations in general. The first cation-cation complex, NpO2+·UO22+, was reported by Sullivan, Hindman, and Zielen in 1961. Of the four actinides that form AnO2+ species, the cation-cation complexes of NpO2+ have been studied most extensively while the other actinides have not. The only PuO2+ cation-cation complexes that have been studied are with Fe3+ and Cr3+ and neither one has had its equilibrium constant measured. Actinides have small molar absorptivities and cation-cation complexes have small equilibrium constants; therefore, to overcome these obstacles a sensitive technique is required. Spectroscopic techniques are used most often to study cation-cation complexes. Laser-Induced Photacoustic Spectroscopy equilibrium constants for the complexes NpO2+·UO22+, NpO2+·Th4+, PuO2+·UO22+, and PuO2+·Th4+ at an ionic strength of 6 M using LIPAS are 2.4 ± 0.2, 1.8 ± 0.9, 2.2 ± 1.5, and ∼0.8 M-1

  3. Causal independence and the energy-level density of states in local quantum field theory

    Within the general framework of local quantum field theory a physically motivated condition on the energy-level density of well-localized states is proposed and discussed. It is shown that any model satisfying this condition obeys a strong form of the principle of causal (statistical) independence, which manifests itself in a specific algebraic structure of the local algebras ('split property'). It is also shown that the proposed condition holds in a free field theory. (orig.)

  4. Microscopic Study of Nuclear Level Densities and Thermal Properties in 56,57Fe

    2007-01-01

    We calculate level densities for 56,57 Fe nuclei using BCS hamiltonian with inclusion of pairing interaction.The results of calculations show that the step structure observed experimentally has been supported by microscopic theory. Also the S-shaped energy and entropy as function of temperature have been obtained in theoretical calculations.Structures in the curves are interpreted as fingerprints of breaking Cooper pairs and quenching of pairing correlations.

  5. Density of States and Zero Landau Level Probed through Capacitance of Graphene

    Ponomarenko, L. A.; Yang, R.(Princeton University, 08544, Princeton, New Jersey, USA); Gorbachev, R.V.; Blake, P.; Mayorov, A. S.; K. S. Novoselov; Katsnelson, M. I.; Geim, A. K.

    2010-01-01

    We report capacitors in which a finite electronic compressibility of graphene dominates the electrostatics, resulting in pronounced changes in capacitance as a function of magnetic field and carrier concentration. The capacitance measurements have allowed us to accurately map the density of states D, and compare it against theoretical predictions. Landau oscillations in D are robust and zero Landau level (LL) can easily be seen at room temperature in moderate fields. The broadening of LLs is ...

  6. Radiometric determinations of linear mass, resin levels and density of composite materials

    A description is given of the principle, characteristics and performances of a gamma back-scattering gauge developed in cooperation between the CEA and SNPE. This instrument allows for on-line inspection of the linear mass and resin level of strips of composite materials whilst being produced. The industrial application involved boron, carbon and 'Kevlar' fibres. The performance of beta and gamma transmission gauges are also given for inspecting the density of panels and dense composite materials

  7. Orbital effects in actinide systems

    Actinide magnetism presents a number of important challenges; in particular, the proximity of 5f band to the Fermi energy gives rise to strong interaction with both d and s like conduction electrons, and the extended nature of the 5f electrons means that they can interact with electron orbitals from neighboring atoms. Theory has recently addressed these problems. Often neglected, however, is the overwhelming evidence for large orbital contributions to the magnetic properties of actinides. Some experimental evidence for these effects are presented briefly in this paper. They point, clearly incorrectly, to a very localized picture for the 5f electrons. This dichotomy only enhances the nature of the challenge

  8. Fabrication of actinide mononitride fuel

    Fabrication of actinide mononitride fuel in JAERI is summarized. Actinide mononitride and their solid solutions were fabricated by carbothermic reduction of the oxides in N2 or N2-H2 mixed gas stream. Sintering study was also performed for the preparation of pellets for the property measurements and irradiation tests. The products were characterized to be high-purity mononitride with a single phase of NaCl-type structure. Moreover, fuel pins containing uranium-plutonium mixed nitride pellets were fabricated for the irradiation tests in JMTR and JOYO. (author)

  9. Towards Synthesis and Usage of Actinide-Bearing REE Phosphate age Standards: A Progress Report

    Pyle, J. M.; Cherniak, D. J.

    2006-05-01

    Electron microprobe (EMP) dates result from a concentration-time unit conversion, so use of a concentration- based (rather than isotope-ratio based) fictive age standard is warranted. This observation has motivated our mineral synthesis program, aimed at producing actinide-doped REE phosphate EMP dating standards that meet the following criteria: 1) known concentrations of U, Th, and Pb; 2) homogeneous intragrain distribution of all components; 3) of suitable size, either as a single-crystal or polycrystalline sintered ceramic. Single-crystal synthesis of actinide-doped LaPO4 by flux-growth methods results in disproportionation of lanthanide and flux, alkali, and actinide components into phosphate and oxide phases, respectively, and flux- growth methods were abandoned. Actinide-doped La phosphate is successfully prepared by high-T annealing and hydrothermal processing of microcrystalline phosphate; both homogeneity and charge-balance of (Ca, Th, Pb)-bearing LaPO4 increase with increasing solvent acidity during cold-seal hydrothermal synthesis. A combination of pressing and high-T (1400° C) sintering transforms fine-grained (0.1-10 μm) run- products to ceramic pellets with 90-95% theoretical density. Our most recent runs focused on a target composition of La80(CaTh)17(CaU)2(PbTh)1PO4 processed with 6% 2M HCl at 820° C, 0.75 kbar for 1 week. The run products are 0.1-2 μm crystals identified by XRD as La-actinide phosphate solid solution. 2 μm grains (N=16) give a composition (mean±2 sd) of La79.77(1.26)(CaTh)17.87(1.00)(CaU)1.53(0.42)(PbTh)0.82(0.09)PO4. Th (8.07-9.13 wt. %) is homogeneous at the level of analytical precision, and the Pb concentration range (3500-4350 ppm) is restricted relative to untreated precipitate. Uranium concentration values are more variable (6500-10000 ppm). This run yields a fictive age of 702±4 Ma (mean±2 se), compared to the fictive age of 794 Ma for the target composition.

  10. New molecules for the separation of actinides (III): the picolinamides

    Minor actinide partitioning from high level liquid wastes produced during the reprocessing of nuclear fuels by the Purex process, requires the design of new extracting molecules. These new extractants must be able to separate, for example, actinides from lanthanides. This separation is very difficult, due to the similar chemical properties of these metallic species, but it can possibly be reached by using extractants with soft donor atoms (N or S). Some new molecules : the picolinamides are investigated in this way. The general chemical formula and the behaviour of these compounds in acidic media are given. (O.L.). 3 refs

  11. Serum oxidized low-density lipoprotein level and risk of cognitive impairment in older women

    Koyama, A; Stone, K.; Yaffe, K

    2012-01-01

    We investigated the association between serum level of oxidized low-density lipoprotein (oxLDL) and risk of cognitive impairment (dementia or mild cognitive impairment) among 572 nondemented community-dwelling women from a prospective cohort study of aging. After 5 years of follow-up, 228 (39.9%) developed cognitive impairment; and this did not differ by tertile of baseline oxLDL level (highest compared with lowest tertile 38.2% vs. 39.5%; odds ratio, 0.90; 95% confidence interval, 0.63-1.43)...

  12. Electronic structure of the actinide dioxides

    The electronic properties of the fluorite structured actinide dioxides have been investigated using the linear muffin tin orbital method in the atomic sphere approximation. CaF2 with the same structure was also studied because of the relative simplicity of its electronic structure and the greater amount of experimental data available. Band structures were calculated both non self consistently and self consistently. In the non self consistent calculations the effect of changing the approximation to the exchange-correlation potential and the starting atomic configurations was examined. Using the concepts of canonical bands the effects of hybridization were investigated. In particular the 5f electrons included in the band picture were found to mix more strongly into the valence band than indicated by experiment. On this basis the 5f electrons were not included in self consistent calculations which in the density functional formalism are capable of yielding ground state properties. Because of the non participation of the f electrons in the bonding UO2 only was considered as representative of the actinide dioxides. For comparison CaF2 was also examined. Using Pettifor's pressure formula to determine the equilibrium condition the lattice constants were calculated to be 0.5% and 5% respectively below the experimental values. (author)

  13. Realistic partial level densities with non-equidistant s.p.l

    Appropriate use of energy-dependent single-particle level (s.p.l.) densities of excited particles and holes within the equidistant spacing model (ESM) formula is analysed. Particle hole bound state density is obtained by means of recursive formula, for energy-dependent s.p.l. corresponding to the Fermi gas model (FGM). Secondly, we adopt the ESM formula but with s.p.l. densities for excited particles and holes calculated within FGM at the respective average single-particle excitation energies u bar also for particle-hole bound states. Corrections for finite nuclear-potential depth, and Pauli, pairing and shell effects are included within both formalisms of particle-hole state densities (PSD), the approximate Pauli correction being found to give results quite close to exact calculation of the Pauli-blocking effect. Comparison of the two approaches supports the use of the average-energy dependent s.p.l. densities within the latter PSD. Consideration of the 'continuum effect' i.e. the subtraction of the contribution of free gas states from the s.p.l. density g(ε) with s.p. energy ε in the continuum region. Quantum-mechanical calculation of the s.p.l. density is carried out by using its relation with the Green function but not the smearing procedure involved by Shlomo. Alternatively, the imaginary part of the Green function is calculated analytically. The smooth part of rapidly fluctuating s.p.l.. density is calculated by means of Strutinsky smoothing procedure. The Woods-Saxon potential has been considered in this frame as well as within semiclassical Thomas-Fermi (TF) formula, with close results. Familiar FGM shape is given by TF formula with infinite square-well potential, while the respective finite well illustrates the continuum effect. On the other hand, even the quantum-mechanically calculated s.p.l. density can be reproduced by simple FGM formula with the average Fermi energy F bar ≅ 20 MeV and subtracted contribution of free-gas states. (authors)

  14. Low energy level density and surface instabilities in heavy transition nuclei

    A statistical analysis of Au, Pt, Hg nuclear levels was performed with Ericson's method. The odd mass gold experimental number of levels distributions are compared to the theoretical distributions corresponding to vibrational (Alaga and Kisslinger-Sorensen) and rotational (Stephens, Meyer-ter-Vehn) models. The Alaga model gives the most complete description of 193Au, 195Au levels and fits the lowest part of Gilbert-Cameron high energy distributions (deduced from the statistical model and neutron capture data). The Ericson's method shows other interesting features of Pt and Hg isotopes (i.e. level density dependence on nuclear shape and pairing correlations, evidence for phase transitions). Consequently, this method is a useful tool for guiding experimental as well as theoretical investigations of transition nuclei

  15. Spin-dependent level density in interacting Boson-Fermion-Fermion model of the Odd-Odd Nucleus 196Au

    The level density of the odd-odd nucleus 196Au is investigated in the interacting boson-fermion-fermion model (IBFFM) which accounts for collectivity and complex interaction between quasiparticle and collective modes.The IBFFM spin-dependent level densities show high-spin reduction with respect to Bethe formula.This can be well accounted for by a modified spin-dependent level density formula. (authors)

  16. First pregnancy characteristics, postmenopausal breast density, and salivary sex hormone levels in a population at high risk for breast cancer

    Mary Mockus

    2015-06-01

    Conclusions and general significance: While reproductive characteristics, in particular parity, generally demonstrated independent associations with postmenopausal breast density and E, P and DHEA levels, T levels showed concordant inverse associations with age-at-first birth and breast density. These findings suggest that reproductive effects and later life salivary sex steroid hormone levels may have independent effects on later life breast density and cancer risk.

  17. Sequential determination of actinides in a variety of matrices

    A large number of analytical procedures for the actinides have been published, each catering for a specific need. Due to the bioassay programme in our laboratory, a need arose for a method to determine natural (Th and U) and anthropogenic actinides (Np, Pu and Am/Cm) together in a variety of samples. The method would have to be suitable for routine application: simple, inexpensive, rapid and robust. In some cases, the amount of material available is not sufficient for the determination of separate groups of actinides, and a sequential separation and measurement of the analytes would therefore be required. The types of matrices vary from aqueous samples to radiological surveillance (urine and faeces) to environmental studies (soil, sediment and fish), but the separation procedure should be able to service all of these. The working range of the method would have to cater for lower levels of the transuranium actinides in particular sample types containing higher levels of the natural actinides (U and Th). The first analytical problem to be discussed, is how to get the different sample types into the same loading solution required by a single separation approach. This entails sample dissolution or decomposition in some cases, and pre-concentration or pre-separation in others. A separation scheme is presented for the clean separation of all the actinides in a form suitable for alpha spectrometry. The development of a single column separation of the analytes of interest are looked at, as well as observations made during the development of the separation scheme, such as concentration effects. Results for test samples and certified reference materials are be presented. (author)

  18. Fast Burner Reactor Devoted to Minor Actinide Incineration

    This study proposes a new fast reactor core concept dedicated to plutonium and minor actinide burning by transmutation. This core has a large power level of ∼1500 MW(electric) favoring the economic aspect. To promote plutonium and minor actinide burning as much as possible, total suppression of 238U, which produces 239Pu by conversion, and large quantities of minor actinides in the core are desirable. Therefore, the 238U-free fuel is homogeneously mixed with a considerable quantity of minor actinides.From the safety point of view, both the Doppler effect and the coolant (sodium) void reactivity become less favorable in a 238U-free core. To preserve these two important safety parameters on an acceptable level, a hydrogenated moderator separated from the fuel and nuclides, such as W or 99Tc, is added to the core in the place of 238U. Tungsten and 99Tc have strong capture resonances at appropriate energies, and 99Tc itself is a long-lived fission product to be transmuted with profit.This core allows the achievement of a consumption rate of ∼100 kg/TW(electric).h of transuranic elements, ∼70 kg/TW(electric).h for plutonium (due to 238U suppression), and 30 to 35 kg/TW(electric).h for minor actinides. In addition, ∼14 kg/TW(electric).h of 99Tc is destroyed when this element is present in the core (the initial loading of 99Tc is >4000 kg in the core).The activity of newly designed subassemblies has also been investigated in comparison to standard fast reactor subassemblies (neutron sources, decay heat, and gamma dose rate). Finally, a transmutation scenario involving pressurized water reactors and minor actinide-burning fast reactors has been studied to estimate the necessary proportion of burner reactors and the achievable radiotoxicity reduction with respect to a reference open cycle

  19. Multidimensionally-constrained relativistic mean-field study of triple-humped barriers in actinides

    Zhao, Jie; Lu, Bingnan; Vretenar, Dario; Zhao, En-Guang; Zhou, Shan-Gui

    2014-01-01

    Potential energy surfaces (PES's) of actinide nuclei are characterized by a two-humped barrier structure. At large deformations beyond the second barrier the occurrence of a third one was predicted by Mic-Mac model calculations in the 1970s, but contradictory results were later reported. In this paper, triple-humped barriers in actinide nuclei are investigated with covariant density functional theory (CDFT). Calculations are performed using the multidimensionally-constrained relativistic mean...

  20. Improving the description of collective effects within the combinatorial model of nuclear level densities

    The combinatorial model of nuclear level densities has now reached a level of accuracy comparable to that of the best global analytical expressions without suffering from the limits imposed by the statistical hypothesis on which the latter expressions rely. In particular, it provides naturally, non Gaussian spin distribution as well as non equipartition of parities which are known to have a significant impact on cross section predictions at low energies. Our first global model developed in Ref. 1 suffered from deficiencies, in particular in the way the collective effects - both vibrational and rotational - were treated. We have recently improved this treatment using simultaneously the single particle levels and collective properties predicted by a newly derived Gogny interaction, therefore enabling a microscopic description of energy-dependent shell, pairing and deformation effects. In addition, for deformed nuclei, the transition to sphericity is coherently taken into account on the basis of a temperature-dependent Hartree-Fock calculation which provides at each temperature the structure properties needed to build the level densities. This new method is described and shown to give promising preliminary results with respect to available experimental data. (authors)

  1. Endurance training associated with slightly lowered serum estradiol levels decreases mineral density of canine skeleton.

    Puustjärvi, K; Karjalainen, P; Nieminen, J; Arokoski, J; Parviainen, M; Helminen, H J; Soimakallio, S

    1992-06-01

    The effects of long-term running exercise were studied in 20 beagle dogs. A total of 10 dogs ran from the age of 15 weeks to the age of 70 weeks in a progressive program for up to 40 km/day. A total of 10 sister dogs spent the study period in individual cages. When the dogs were 70 weeks old, bone mineral density of the vertebrae, hip, and radius was analyzed by dual-energy x-ray absorptiometry (DEXA; Lunar) and the vertebrae were also assessed by quantitative computed tomography (QCT; Siemens DR 1). Mineral density was lower in the running dogs than in the controls. The difference was greatest in the spine in the QCT analysis. Blood chemistry analyses revealed that the metabolism of the bone was significantly accelerated. The estradiol levels showed the trend to be reduced in the running group. The beneficial effect of exercise on mineral density has been shown in many earlier studies. However, in this study we demonstrate the possibility of adverse effects of long-term exercise on bone tissue. The change was associated with a decrease of serum estradiol level. PMID:1414479

  2. Environmental research on actinide elements

    Pinder, J.E. III; Alberts, J.J.; McLeod, K.W.; Schreckhise, R.G. (eds.)

    1987-08-01

    The papers synthesize the results of research sponsored by DOE's Office of Health and Environmental Research on the behavior of transuranic and actinide elements in the environment. Separate abstracts have been prepared for the 21 individual papers. (ACR)

  3. ENDF/B-V actinides

    This document summarizes the contents of the actinides part of the ENDF/B-V nuclear data library released by the US National Nuclear Data Center. This library or selective retrievals of it, are available from the IAEA Nuclear Data Section. (author)

  4. Excited-state quantum phase transitions in systems with two degrees of freedom: Level density, level dynamics, thermal properties

    Quantum systems with a finite number of freedom degrees f develop robust singularities in the energy spectrum of excited states as the system’s size increases to infinity. We analyze the general form of these singularities for low f, particularly f=2, clarifying the relation to classical stationary points of the corresponding potential. Signatures in the smoothed energy dependence of the quantum state density and in the flow of energy levels with an arbitrary control parameter are described along with the relevant thermodynamical consequences. The general analysis is illustrated with specific examples of excited-state singularities accompanying the first-order quantum phase transition. -- Highlights: •ESQPTs found in infinite-size limit of systems with low numbers of freedom degrees f. •ESQPTs related to non-analytical evolutions of classical phase–space properties. •ESQPT signatures analyzed for general f, particularly f=2, extending known case f=1. •ESQPT signatures identified in smoothened density and flow of energy spectrum. •ESQPTs shown to induce a new type of thermodynamic anomalies

  5. Evaluation study on properties of a macroporous silica-based CMPO extraction resin to be used forminor actinides separation from high level liquid waste

    Basic properties of a silica-based octyl (phenyl)-N, N-diisobutylcarbamoyl-methylphosphine oxide (CMPO) extraction resin (CMPO/SiO2-P) was investigated. Adsorption behavior for some rare earth elements (RE) which are constituents of high level liquid waste (HLLW) and the long-term stability of the extraction resin in nitric acid solution were examined. The CMPO extraction resin was significantly stable in 3 mol·L-1 HNO3 solution at 50 degree C. Furthermore, the RE (III) were efficiently separated from non-adsorptive fission product (FP) elements such as Sr (II) in a column experiment using a highly nitric acid solution. The separation behaviors of the elements are considered to result from the difference in their adsorption and elution selectivity based on the complex formation with CMPO. There was no strong dependency of RE (III) separation efficiency on feed solution flow rate. Only from the perspectives of the acid-resistant behavior of CMPO extraction resin and the elution kinetics for the metal ions with the extraction resin, the CMPO extraction resin can be used in the modified MAREC process for HLLW partitioning. (authors)

  6. Evaluation of the thermodynamics of a four level system using canonical density matrix method

    Awoga Oladunjoye A.

    2013-02-01

    Full Text Available We consider a four-level system with two subsystems coupled by weak interaction. The system is in thermal equilibrium. The thermodynamics of the system, namely internal energy, free energy, entropy and heat capacity, are evaluated using the canonical density matrix by two methods. First by Kronecker product method and later by treating the subsystems separately and then adding the evaluated thermodynamic properties of each subsystem. It is discovered that both methods yield the same result, the results obey the laws of thermodynamics and are the same as earlier obtained results. The results also show that each level of the subsystems introduces a new degree of freedom and increases the entropy of the entire system. We also found that the four-level system predicts a linear relationship between heat capacity and temperature at very low temperatures just as in metals. Our numerical results show the same trend.

  7. Level-density parameters for back-shifted Fermi-gas model

    On the base of evaluated experimental data and created systematics the parameters a and δeff for the back-shifted Fermi gas model are determined for ∼ 3000 nuclei. For 272 nuclei the parameters are determined from experimental data on cumulative numbers of low-lying levels and the average spacings between neutron resonances. For 952 nuclei the δeff parameter is determined from cumulative numbers of low-lying levels and values of a-parameter obtained by interpretation of data for 272 nuclei. For the rest nuclei parameters a and δeff are obtained from the systematics created. The formula for the account of the damping of the shell effect at high excitation energies is suggested. A comparison is given with previous results and different experimental data on the level densities

  8. Burning of actinides: A complementary waste management option?

    The TRU actinide are building up at a rate of about 90 tHM per year. Approximately 45 tHM will remain occluded in the spent fuel structures, leaving about 45 tHM available; 92% as recycled plutonium and 8% as minor actinides (neptunium, americium, curium) immobilized in vitrified waste. There is renewed interest in partitioning and transmutation (P and T), largely because of difficulties encountered throughout the world in finding suitable geologic formations in locations which are acceptable to the public. In 1988, the Japanese Atomic Energy Commission launched a very important and comprehensive R and D program. The general strategy of introducing Partitioning and Transmutation (P and T) as an alternative waste management option is based on the radiological benefit which is expected from such a venture. The selection of the actinides and long-lived fission products which are beneficial to eliminate by transmutation depends upon a number of technical factors, including hazard and decontamination factors, and the effect of geological confinement. There are two ways to approach the separation of minor actinides and long-lived fission products from reprocessing streams: by modifying the current processes in order to reroute the critical nuclides into a single solution, for example high-level liquid waste, and use this as a source for partitioning processes; and by extension of the conventional PUREX process to all minor actinides and long-lived fission products in second generation reprocessing plants. Prior to the implementation of one of these schemes, it seems obvious to improve the separation yield of plutonium from HLW within the presently running plants. Actinide P and T is not an alternative long-term waste management option. Rather, it is a complementary technique to geologic disposal capable of further decreasing the radiological impact of the fuel cycle over the very long term. 1 tab

  9. The Dirac equation in electronic structure calculations: Accurate evaluation of DFT predictions for actinides

    Wills, John M [Los Alamos National Laboratory; Mattsson, Ann E [Sandia National Laboratories

    2012-06-06

    Brooks, Johansson, and Skriver, using the LMTO-ASA method and considerable insight, were able to explain many of the ground state properties of the actinides. In the many years since this work was done, electronic structure calculations of increasing sophistication have been applied to actinide elements and compounds, attempting to quantify the applicability of DFT to actinides and actinide compounds and to try to incorporate other methodologies (i.e. DMFT) into DFT calculations. Through these calculations, the limits of both available density functionals and ad hoc methodologies are starting to become clear. However, it has also become clear that approximations used to incorporate relativity are not adequate to provide rigorous tests of the underlying equations of DFT, not to mention ad hoc additions. In this talk, we describe the result of full-potential LMTO calculations for the elemental actinides, comparing results obtained with a full Dirac basis with those obtained from scalar-relativistic bases, with and without variational spin-orbit. This comparison shows that the scalar relativistic treatment of actinides does not have sufficient accuracy to provide a rigorous test of theory and that variational spin-orbit introduces uncontrolled errors in the results of electronic structure calculations on actinide elements.

  10. Delayed Proton Emission in the A=70 Region, a Strobe for Level Density and Particle Width

    2002-01-01

    The delayed particle emission, which is a characteristic signature of the most exotic nuclei decay, provides a wide variety of spectroscopic information among which level density, and gives in some cases access to selected microscopic structures. In regard to these two aspects the $\\beta^+$-EC delayed proton emission in the A=70 neutron deficient mass region is of special interest to be investigated. Indeed, in this area located close to the proton drip line and along the N=Z line, the delayed proton emission constitutes an access to level density in the Q$_{EC}$-S$_p$ window of the emitting nucleus. Moreover, the unbound states populated by the EC process are expected to exhibit lifetimes in the vicinity of the K electronic shell filling time ($\\tau\\!\\sim\\!2\\times10^{-16}$s) and so the particle widths can be reached via proton X-ray coincidence measurements (PXCT). From theoretical approaches strongly deformed low-spin proton unbound levels which may be populated in the T$_Z$ = 1/2 precursors decay are predi...

  11. Increasing the maximally random jammed density with electric field to reduce the fat level in chocolate

    Tao, R.; Tang, H.

    Chocolate is one of the most popular food types and flavors in the world. Unfortunately, at present, chocolate products contain too much fat, leading to obesity. For example, a typical molding chocolate has various fat up to 40% in total and chocolate for covering ice cream has fat 50 -60%. Especially, as children are the leading chocolate consumers, reducing the fat level in chocolate products to make them healthier is important and urgent. While this issue was called into attention and elaborated in articles and books decades ago and led to some patent applications, no actual solution was found unfortunately. Why is reducing fat in chocolate so difficult? What is the underlying physical mechanism? We have found that this issue is deeply related to the basic science of soft matters, especially to their viscosity and maximally random jammed (MRJ) density φx. All chocolate productions are handling liquid chocolate, a suspension with cocoa solid particles in melted fat, mainly cocoa butter. The fat level cannot be lower than 1-φxin order to have liquid chocolate to flow. Here we show that that with application of an electric field to liquid chocolate, we can aggregate the suspended particles into prolate spheroids. This microstructure change reduces liquid chocolate's viscosity along the flow direction and increases its MRJ density significantly. Hence the fat level in chocolate can be effectively reduced. We are looking forward to a new class of healthier and tasteful chocolate coming to the market soon. Dept. of Physics, Temple Univ, Philadelphia, PA 19122.

  12. ON THE QUESTIONS OF THE NUCLEAR LEVEL DENSITY AND THE E1 PHOTON STRENGTH FUNCTIONS

    MUGHABGHAB,S.F.; DUNFORD,C.L.

    1999-11-15

    New results were derived from average level spacings of neutron resonances for the spin dispersion parameter of the nuclear level density, which demonstrated the influence of shell effects, as well as the interplay of nucleon pairing correlations for nuclei in the mass range from {sup 29}Si to {sup 241}Pu. The volume and surface components of the nuclear level density parameter, as well as the shell-damping factor, were determined as, a{sub v} = 0.076 {+-} 0.009 MeV{sup {minus}1} , a{sub s} = 0.180 {+-} 0.047 MeV{sup {minus}1}, and y{sub 0} = 0.047 {+-} 0.04 MeV{+-}, respectively. The effective nucleon mass at the Fermi surface is derived as m*/m = 1.09 {+-} 0.13. New evidence is presented for a dipole-quadrupole interaction term in the primary E1 transitions of average resonance capture data. This evidence is obtained by testing a proposed generalized Landau Fermi liquid model for spherical and deformed nuclei, which includes the effect of the dipole-quadrupole interaction. The Landau-Migdal interaction constant and the effective nucleon mass, are determined as F{sub 0}{prime} = 1.49 {+-} 0.08, and m*/m=1.04 {+-} 0.07, respectively.

  13. Density matrix reconstruction of three-level atoms via Rydberg electromagnetically induced transparency

    Gavryusev, V.; Signoles, A.; Ferreira-Cao, M.; Zürn, G.; Hofmann, C. S.; Günter, G.; Schempp, H.; Robert-de-Saint-Vincent, M.; Whitlock, S.; Weidemüller, M.

    2016-08-01

    We present combined measurements of the spatially resolved optical spectrum and the total excited-atom number in an ultracold gas of three-level atoms under electromagnetically induced transparency conditions involving high-lying Rydberg states. The observed optical transmission of a weak probe laser at the center of the coupling region exhibits a double peaked spectrum as a function of detuning, while the Rydberg atom number shows a comparatively narrow single resonance. By imaging the transmitted light onto a charge-coupled-device camera, we record hundreds of spectra in parallel, which are used to map out the spatial profile of Rabi frequencies of the coupling laser. Using all the information available we can reconstruct the full one-body density matrix of the three-level system, which provides the optical susceptibility and the Rydberg density as a function of spatial position. These results help elucidate the connection between three-level interference phenomena, including the interplay of matter and light degrees of freedom and will facilitate new studies of many-body effects in optically driven Rydberg gases.

  14. Density matrix reconstruction of three-level atoms via Rydberg electromagnetically induced transparency

    Gavryusev, V; Ferreira-Cao, M; Zürn, G; Hofmann, C S; Günter, G; Schempp, H; Robert-de-Saint-Vincent, M; Whitlock, S; Weidemüller, M

    2016-01-01

    We present combined measurements of the spatially-resolved optical spectrum and the total excited-atom number in an ultracold gas of three-level atoms under electromagnetically induced transparency conditions involving high-lying Rydberg states. The observed optical transmission of a weak probe laser at the center of the coupling region exhibits a double peaked spectrum as a function of detuning, whilst the Rydberg atom number shows a comparatively narrow single resonance. By imaging the transmitted light onto a charge-coupled-device camera, we record hundreds of spectra in parallel, which are used to map out the spatial profile of Rabi frequencies of the coupling laser. Using all the information available we can reconstruct the full one-body density matrix of the three-level system, which provides the optical susceptibility and the Rydberg density as a function of spatial position. These results help elucidate the connection between three-level interference phenomena, including the interplay of matter and li...

  15. On the questions of the nuclear level density and the E1 photon strength functions

    New results were derived from average level spacings of neutron resonances for the spin dispersion parameter of the nuclear level density, which demonstrated the influence of shell effects, as well as the interplay of nucleon pairing correlations for nuclei in the mass range from 29Si to 241Pu. The volume and surface components of the nuclear level density parameter, as well as the shell-damping factor, were determined as, av 0.076 ± 0.009 MeV-1, as = 0.180±0.047MeV-1, and γ0 = 0.047 ±0.04MeV-1, respectively. The effective nucleon mass at the Fermi surface is derived as m*/m = 1.09±0.13. New evidence is presented for a dipole-quadrupole interaction term in the primary E1 transitions of average resonance capture data. This evidence is obtained by testing a proposed generalized Landau Fermi liquid model for spherical and deformed nuclei, which includes the effect of the dipole-quadrupole interaction. The Landau-Migdal interaction constant and the effective nucleon mass, are determined as F0' = 1.49 ± 0.08, and m*/m = 1.04 ± 0.07, respectively. (author)

  16. On the questions of the nuclear level density and the E1 photon strength functions

    New results were derived from average level spacings of neutron resonances for the spin dispersion parameter of the nuclear level density, which demonstrated the influence of shell effects, as well as the interplay of nucleon pairing correlations for nuclei in the mass range from 29Si to 241Pu. The volume and surface components of the nuclear level density parameter, as well as the shell-damping factor, were determined as, av = 0.076 ± 0.009 MeV-1 , as = 0.180 ± 0.047 MeV-1, and y0 = 0.047 ± 0.04 MeV±, respectively. The effective nucleon mass at the Fermi surface is derived as m*/m = 1.09 ± 0.13. New evidence is presented for a dipole-quadrupole interaction term in the primary E1 transitions of average resonance capture data. This evidence is obtained by testing a proposed generalized Landau Fermi liquid model for spherical and deformed nuclei, which includes the effect of the dipole-quadrupole interaction. The Landau-Migdal interaction constant and the effective nucleon mass, are determined as F0prime = 1.49 ± 0.08, and m*/m=1.04 ± 0.07, respectively

  17. Solidification of simulated actinides by natural zircon

    YANG Jian-Wen; LUO Shang-Geng

    2004-01-01

    Natural zircon was used as precursor material to produce a zircon waste form bearing 20wt% simulated actinides (Nd2O3 and UO2) through a solid state reaction by a typical synroc fabrication process. The fabricated zircon waste form has relatively good physical properties (density 5.09g/cm3, open porosity 4.0%, Vickers hardness 715kg/mm2). The XRD, SEM/EDS and TEM/EDS analyses indicate that there are zircon phases containing waste elements formed through the reaction. The chemical durability and radiation stability are determined by the MCC-1method and heavy ion irradiation; the results show that the zircon waste form is highly leach resistance and relatively stable under irradiation (amorphous dose 0.7dpa). From this study, the method of using a natural mineral to solidify radioactive waste has proven to be feasible.

  18. The Hagedorn spectrum, nuclear level densities and first order phase transitions

    Moretto, Luciano G., E-mail: lgmoretto@lbl.gov [Department of Chemistry, University of California, Berkeley, Lawrence Berkeley National Laboratory 1 Cyclotron Road, Berkeley, CA 94720 (United States); Larsen, A. C.; Guttormsen, M.; Siem, S. [Department of Physics, University of Oslo, N-0316 Oslo (Norway)

    2015-10-15

    An exponential mass spectrum, like the Hagedorn spectrum, with slope 1/T{sub H} was interpreted as fixing an upper limiting temperature T{sub H} that the system can achieve. However, thermodynamically, such spectrum indicates a 1{sup st} order phase transition at a fixed temperature T{sub H}. A much lower energy example is the log linear level nuclear density below the neutron binding energy that prevails throughout the nuclear chart. We show that, for non-magic nuclei, such linearity implies a 1{sup st} order phase transition from the pairing superfluid to an ideal gas of quasi particles.

  19. LEVEL DENSITY AND FINITE-TEMPERATURE SPECIFIC HEATOF NUCLEUS 104pd UNDER MICROSCOPIC IBM

    石筑一; 刘庸; 桑建平

    2001-01-01

    By using the microscopic sdgIBM-Fmax approach, the procedure of canonical ensemble average and the saddle point approximation, the thermodynamics of the nucleus is established under microscopic IBM. Calculations of spectrum, level density and finite-temperature specific heat for the nucleus 104pd are carried out. The calculated values are coincident with the experimental data reported recently. The results predict that the shape phase transition in the groundstate band appears at about T ≈0.230MeV and the phase transition of the thermal excitation mode takes place at T ≈0.630 MeV for the nucleus 104pd.

  20. Level Density In Interacting Boson-Fermion-Fermion Model (IBFFM) Of The Odd-Odd Nucleus 196Au

    The level density of the odd-odd nucleus 196Au is investigated in the interacting boson-fermion-fermion model (IBFFM) which accounts for collectivity and complex interaction between quasiparticle and collective modes.The IBFFM total level density is fitted by Gaussian and its tail is also fitted by Bethe formula and constant temperature Fermi gas model

  1. Fusion-Fission Burner for Transuranic Actinides

    Choi, Chan

    2013-10-01

    The 14-MeV DT fusion neutron spectrum from mirror confinement fusion can provide a unique capability to transmute the transuranic isotopes from light water reactors (LWR). The transuranic (TRU) actinides, high-level radioactive wastes, from spent LWR fuel pose serious worldwide problem with long-term decay heat and radiotoxicity. However, ``transmuted'' TRU actinides can not only reduce the inventory of the TRU in the spent fuel repository but also generate additional energy. Typical commercial LWR fuel assemblies for BWR (boiling water reactor) and PWR (pressurized water reactor) measure its assembly lengths with 4.470 m and 4.059 m, respectively, while its corresponding fuel rod lengths are 4.064 m and 3.851 m. Mirror-based fusion reactor has inherently simple geometry for transmutation blanket with steady-state reactor operation. Recent development of gas-dynamic mirror configuration has additional attractive feature with reduced size in central plasma chamber, thus providing a unique capability for incorporating the spent fuel assemblies into transmutation blanket designs. The system parameters for the gas-dynamic mirror-based hybrid burner will be discussed.

  2. Transmutation of minor actinides in a Candu thorium borner

    flattening as well as long term reactivity have been found by mixing thoria with 14% minor actinides in form of MAO2 in the central fuel bundle and decreasing radially MAO2 content at discrete levels down to 2% at the periphery. Furthermore, as alternative fuel, 5% UO2 has been added to the mixed fuel for the sake of a higher degree of nuclear safeguarding through denaturing the 233U component with 238U. The temporal variation of the criticality k∞ and the burn-up values of the reactor have been calculated for a period of 10 years, operated at full power. The criticality starts at time zero near to k∞ = ∼ 1.24 for both fuel compositions. A sharp decrease of the criticality has been observed during the first year as a consequence of rapid plutonium burnout in the actinide fuel. The criticality becomes quasi constant after the 2nd year after sufficient 233U is accumulated and remains close to k∞,end ∼1.06 over ∼ 10 years. Quasi-uniform power generation density has been realized in the fuel bundle throughout the reactor operation

  3. Evaluation of Digestible lysine levels in diets with high energy density for finishing pigs

    Janeth Colina R

    2015-05-01

    Full Text Available ABSTRACT Objective. To evaluate the effects of different levels of digestible lysine in diets with high energy density on productive performance and carcass characteristics of finishing pigs. Materials and Methods. Seventy crossbred barrows (initial body weight of 83.36 kg were used and allotted in a randomized block design with five treatments, seven replications and two pigs per experimental unit. Pigs were fed ad libitum with diets containing 3.5 kcal/kg of ME and five levels of digestible lysine (0.46, 0.52, 0.58, 0.64 and 0.70% during four weeks. Final live weight (FLW, daily feed intake (DFI, daily weight gain (DWG, feed conversion (FC, daily lysine intake (DLI, and the amount of lysine per body weight gain (DLI/DWG, were evaluated. At the end of the experiment, blood samples were taken from each pig to determine urea nitrogen concentration (UN in serum and slaughtered to evaluate quantitative and qualitative carcass characteristics. Results. The FLW increased linearly (p<0.05.There were no differences among treatments for DFI, DWG, FC, carcass characteristics and UN. The DLI and DLI/DWG varied significantly (p<0.001 and increased linearly (p<0.001 with each lysine level. Pigs that consumed the limiting diet in lysine (0.46% showed less DLI and DLI/DWG (p<0.001 than pigs fed the other diets. Conclusions. The amount of DLI/DWG increased with the evaluated levels of digestible lysine in diets with high energy density, without effects on productive performance and carcass characteristics of finishing pigs.

  4. Evidence for low high-density lipoprotein cholesterol levels in Australian indigenous peoples: a systematic review

    2014-01-01

    Background Low plasma high-density lipoprotein cholesterol (HDL-C) levels are a strong, independent, but poorly understood risk factor for cardiovascular disease (CVD). Although this atherogenic lipid abnormality has been widely reported in Australia’s Indigenous peoples, Aboriginal and Torres Strait Islanders, the evidence has not come under systematic review. This review therefore examines published data for Indigenous Australians reporting 1) mean HDL-C levels for both sexes and 2) factors associated with low HDL-C. Methods PubMed, Medline and Informit ATSI Health databases were systematically searched between 1950 and 2012 for studies on Indigenous Australians reporting mean HDL-C levels in both sexes. Retrieved studies were evaluated by standard criteria. Low HDL-C was defined as: Australian Aborigines, mean HDL-C values ranged between 0.81-1.50 mmol/L in females and 0.76-1.60 mmol/L in males. Two of 15 studies reported HDL-C levels for Torres Strait Islander populations, mean HDL-C: 1.00 or 1.11 mmol/L for females and 1.01 or 1.13 mmol/L for males. Low HDL-C was observed only in rural/regional and remote settings - not in national or urban studies (n = 3) in either gender. Diabetes prevalence, mean/median waist-to-hip ratio and circulating C-reactive protein levels were negatively associated with HDL-C levels (all P Australian Indigenous populations living in rural and remote communities. Inverse associations between HDL-C and central obesity, diabetes prevalence and inflammatory markers suggest a particularly adverse CVD risk factor profile. An absence of sex dichotomy in HDL-C levels warrants further investigation. PMID:24888391

  5. Reduced Amylin Levels Are Associated with Low Bone Mineral Density in Women with Anorexia Nervosa

    Wojcik, Monica H; Meenaghan, Erinne; Lawson, Elizabeth A; Misra, Madhusmita; Klibanski, Anne; Miller, Karen K

    2009-01-01

    Context Anorexia nervosa, characterized by extreme low body weight due to reduced nutrient intake, is associated with severe bone loss. Peptide hormones, including amylin, GIP, and GLP2, are released immediately after nutrient intake and may be involved in the regulation of bone turnover. Objective To investigate fasting levels of amylin, GIP, and GLP2 and their relationships with bone mineral density (BMD) in women with anorexia nervosa compared to healthy controls. Design Cross-sectional Setting Clinical Research Center Study Participants 15 women with anorexia nervosa and 16 healthy controls Intervention None Main Outcome Measures Fasting serum amylin, GIP, and GLP2, and BMD Results Women with anorexia nervosa had significantly lower fasting serum amylin and GIP levels than healthy controls. Fasting serum GLP2 levels were not significantly different between groups. Fasting amylin levels were positively associated with BMD and Z-score at the PA spine, total hip, and femoral neck. Fasting amylin levels were also positively associated with weight and percent fat; after controlling for these variables, amylin was still a significant predictor of BMD and Z-score at the femoral neck and of Z-score at the total hip. In the anorexia nervosa group, there was a trend toward an inverse association between amylin and C-terminal telopeptide (CTX) levels (R = −0.47, p = 0.08). GIP and GLP2 levels did not predict BMD at any site. Conclusion Decreased secretion of amylin may be a mechanism through which reduced nutrient intake adversely affects BMD in anorexia nervosa. PMID:19931436

  6. Synergistic extraction of actinides : Part II. Tetra-and trivalent actinides

    A detailed discussion on the synergistic solvent extraction behaviour of tetra- and trivalent actinide ions is presented. Structural aspects of the natural donor adducts of the tetravalent actinide ion chelates involved in synergism are also discussed. (author)

  7. Actinide chemistry in ionic liquids.

    Takao, Koichiro; Bell, Thomas James; Ikeda, Yasuhisa

    2013-04-01

    This Forum Article provides an overview of the reported studies on the actinide chemistry in ionic liquids (ILs) with a particular focus on several fundamental chemical aspects: (i) complex formation, (ii) electrochemistry, and (iii) extraction behavior. The majority of investigations have been dedicated to uranium, especially for the 6+ oxidation state (UO2(2+)), because the chemistry of uranium in ordinary solvents has been well investigated and uranium is the most abundant element in the actual nuclear fuel cycles. Other actinides such as thorium, neptunium, plutonium, americium, and curiumm, although less studied, are also of importance in fully understanding the nuclear fuel engineering process and the safe geological disposal of radioactive wastes. PMID:22873132

  8. Study of Photon Strength Functions of Actinides: the case of U-235, Np-238 and Pu-241

    Guerrero, C; Cano-Ott, D; Martinez, T; Mendoza, E; Villamarin, D; Colonna, N; Meaze, M H; Marrone, S; Tagliente, G; Terlizzi, R; Belloni, F; Abbondanno, U; Fujii, K; Milazzo, P M; Moreau, C; Aerts, G; Berthoumieux, E; Dridi, W; Gunsing, F; Pancin, J; Perrot, L; Plukis, A; Alvarez, H; Duran, I; Paradela, C; Andriamonje, S; Calviani, M; Chiaveri, E; Gonzalez-Romero, E; Kadi, Y; Vicente, M C; Vlachoudis, V; Andrzejewski, J; Marganiec, J; Assimakopoulos, P; Karadimos, D; Karamanis, D; Papachristodoulou, C; Patronis, N; Audouin, L; David, S; Ferrant, L; Isaev, S; Stephan, C; Tassan-Got, L; Badurek, G; Jericha, E; Leeb, H; Oberhummer, H; Pigni, M T; Baumann, P; Kerveno, M; Lukic, S; Rudolf, G; Becvar, F; Krticka, M; Calvino, F; Capote, R; Carrillo De Albornoz, A; Marques, L; Salgado, J; Tavora, L; Vaz, P; Cennini, P; Dahlfors, M; Ferrari, A; Gramegna, F; Herrera-Martinez, A; Mastinu, P; Praena, J; Sarchiapone, L; Wendler, H; Chepel, V; Ferreira-Marques, R; Goncalves, I; Lindote, A; Lopes, I; Neves, F; Cortes, G; Poch, A; Pretel, C; Couture, A; Cox, J; O'brien, S; Wiescher, M; Dillman, I; Kappeler, F; Mosconi, M; Plag, R; Voss, F; Walter, S; Wisshak, K; Dolfini, R; Rubbia, C; Domingo-Pardo, C; Tain, J L; Eleftheriadis, C; Savvidis, I; Frais-Koelbl, H; Griesmayer, E; Furman, W; Konovalov, V; Goverdovski, A; Ketlerov, V; Haas, B; Haight, R; Reifarth, R; Heil, M; Igashira, M; Koehler, P; Kossionides, E; Lampoudis, C; Lozano, M; Quesada, J; Massimi, C; Vannini, G; Mengoni, A; Oshima, M; Papadopoulos, C; Vlastou, R; Pavlik, A; Pavlopoulos, P; Plompen, A; Rullhusen, P; Rauscher, T; Rosetti, M; Ventura, A

    2011-01-01

    The decay from excited levels in medium and heavy nuclei can be described in a statistical approach by means of Photon Strength Functions and Level Density distributions combined with the theory of the compound. The study of electromagnetic cascades following neutron capture by means of high efficiency detectors has been shown to be well suited for probing the properties of the Photon Strength Function of heavy (high level density) and/or radioactive (high background) nuclei. In this work we have investigated for the first time the validity of the recommended PSF for actinides, in particular 235U, 238Np and 241Pu. Our study includes the search for resonance structures in the PSF below Sn and draws conclusions regarding their existence and their characteristics in terms of energy, width and electromagnetic nature.

  9. Characteristics of High-density Lipoprotein Subclasses Distribution for Subjects with Desirable Total Cholesterol Levels

    Xu Yanhua

    2011-04-01

    Full Text Available Abstract Background To investigate alteration of high density lipoproteins (HDL subclasses distribution in different total cholesterol (TC levels, mainly the characteristics of HDL subclasses distribution in desirable TC levels and analyze the related mechanisms. Methods ApoA-I contents of plasma HDL subclasses were determined by 2-dimensional gel electrophoresis coupled with immunodetection. 486 Chinese Adults subjects were assigned to different TC groups according to the third Report of NCEP (ATP- III guidelines. Results The increase in contents of small preβ1-HDL, HDL3c, HDL3b, and HDL3a particles clustered and reduce in HDL2b with increased of TC. The distribution of HDL subclasses have shown abnormality characterized by the lower HDL2b (324.2 mg/L contents and the higher preβ1-HDL (90.4 mg/L contents for desirable TC Chinese subjects. Among 176 desirable TC subjects, 58.6% subjects with triglyceride (TG Conclusions The particles size of HDL subclasses shifted towards smaller with increased TC levels. The TC was liner with HDL2b contents and those can be reduced 17 mg/L for 0.5 mmol/L increment in TC levels. The HDL subclasses distribution phenotype was not expectation for Chinese Population with desirable TC levels. Thus, from the HDL subclasses distribution point, when assessing the coronary heart disease(CHD risk not only rely on the TC levels, but also the concentrations of TG, HDL-C and LDL-C must considered in case the potential risk for desirable TC subjects with other plasma lipids metabolism disorders.

  10. Relation of Vitamin B12 Levels to Bone Mineral Density of Postmenopausal Women - Original Investigation

    Nur Kesiktaş

    2009-04-01

    Full Text Available Aim: Although vitamin B12 (vit-B12 is known to influence the hemopoeitic and nervous systems, little is known about the skeletal effects of vit-B12. Researchs that demonstrated an association between serum vitamin B-12 concentration and osteoblastic function and its’ role in DNA synthesis, which suggesting a relationship between osteoporosis, this randomized controlled trial were planned. Material and Methods: Vit-B12 levels of 740 patients aged between 50-65 years, who were applied to our outpatient clinic because of chronic low back pain were examined and divided with vitamin B-12 levels over or below 400 pg/ml. 26 participant who met all inclusion criteria with vit-B12 level below 400pg/ml were assigned to case group. Among the patients that vit-B12 levels were over 400pg/ml, 20 participants were randomly selected to control group. Bone mineral density (BMD, biochemical measurements, causes of osteoporosis and vit-B12 defiencies were investigated. A computer program was used for statistic evaluation. Results: There was not statistically significant difference between BMD’s of case and control groups (p>0.05. When the vit-B12 levels were grouped with over 400 pg/ml, below 200 pg/ml and between 200-400 pg/ml, osteodensimetric examinations of femur neck BMD (p<0.05 were achieved statistically significant difference. Conclusion: The results of this trial highlight an association of vitamin B-12 status with osteoporosis. Vit-B12 defiency is an easy and cheap treatable condition so that reason we suggest that levels of vit-B12 should be investigated. (From the World of Osteoporosis 2009;15:1-6

  11. Actinide speciation bound to hydrous ferric oxide colloids in the near-field conditions of the waste pond at 'Mayak' facility (Russia)

    Full text of publication follows: 'Mayak' facility is a nuclear waste and spent nuclear fuel reprocessing plant located in Ural Mountains, Russia. The opened pond, Karachay Lake, was used for several decades for the discharge of low- and intermediate level waste solutions containing fission products and traces of actinides. Due to high salt concentration and high density of waste solutions, they are penetrating into the groundwater system that is represented by oxic Eh conditions. The speciation of actinides in groundwater samples collected close to Karachay Lake was studied by successive micro- and ultra-filtrations with subsequent SEM, TEM, nano-SIMS, membrane extraction and other techniques. It was established that U and Np were found in soluble fraction (pass through 10 kD ultra-filter) in the form of their bi- and tri-carbonate complexes that was supported by chemical thermodynamic calculations. In contrast, Pu and Am were bound to nano-colloids 10 kD - 50 nm in size. The SEM and TEM data indicate the presence of variety of different colloidal particles which relative concentration decrease in the row: hydrous ferric oxides (HFO) >> clays ≅ calcite > rutile ≅ hematite ≅ barite ≅ MnO2 > monazite > other phases. The SIMS with submicron resolution (Cameca nanoSIMS-50) was used to study local concentration of actinides. According to the obtained data among different colloids detected in the sample actinides were preferentially bound to HFO and MnO2 while other phases did not sorb actinides. In order to determine actinide speciation bound to HFO colloids XPS and An L3 edge XAFS measurements were done at Siberian Synchrotron Radiation Centre. The storage ring VEPP-3 with electron beam energy of 2 GeV and an average stored current of 80 mA was used as the source of radiation. Since the concentration of actinides in actual samples was too low for XAFS, the samples for measurements were prepared by contacting about 10-5 M solutions of Np(V) and Pu(V) with UFO

  12. ACTINET: Establishment of a network of excellence for actinide sciences

    During the past decades, the actinide sciences have stagnated and become less attractive for young scientists, particularly in European countries. The safety requirements for maintaining up-to-date experimental capacities for handling alpha-emitting compounds, such as actinides, have gradually made researches very costly, and many radiochemistry laboratories have restricted their activities largely to beta- and gamma-emitting materials. This trend has dramatically reduced basic research in actinide sciences in Europe, and at present, only few national research institutions and one institute of the Joint Research Centre (ITU) are able to maintain the necessary research infrastructure. Very few laboratories in Europe possess now the expertise, technical competence and tools at the scale required by the technical challenges faced by the European countries, and none of them alone covers the full spectrum required. Furthermore, there are only a few places in Europe that have the appropriate research facilities to support education in actinide sciences with the appropriate research experience. Because of its strategic importance, the research in actinide sciences must therefore be revitalized, and become attractive again to students so that a next generation of actinide scientists and engineers can rise from the radiochemistry laboratories of universities. To sustain and disseminate the indispensable knowledge and expertise, as well as to maintain the threshold level of research activity in actinide sciences in Europe, success can only be envisaged by the use of Europe-wide networking. This particular research area requires reinforced links between national nuclear research institutes, the JRC, and radiochemistry laboratories of a number of academic research organisations: networking will not only facilitate the coordination and utilization of available facilities, but will also consolidate, optimise, and give the necessary impetus to enliven the research and training

  13. Zirconium behaviour during electrorefining of actinide-zirconium alloy in molten LiCl-KCl on aluminium cathodes

    Meier, R.; Souček, P.; Malmbeck, R.; Krachler, M.; Rodrigues, A.; Claux, B.; Glatz, J.-P.; Fanghänel, Th.

    2016-04-01

    A pyrochemical electrorefining process for the recovery of actinides from metallic nuclear fuel based on actinide-zirconium alloys (An-Zr) in a molten salt is being investigated. In this process actinides are group-selectively recovered on solid aluminium cathodes as An-Al alloys using a LiCl-KCl eutectic melt at a temperature of 450 °C. In the present study the electrochemical behaviour of zirconium during electrorefining was investigated. The maximum amount of actinides that can be oxidised without anodic co-dissolution of zirconium was determined at a selected constant cathodic current density. The experiment consisted of three steps to assess the different stages of the electrorefining process, each of which employing a fresh aluminium cathode. The results indicate that almost a complete dissolution of the actinides without co-dissolution of zirconium is possible under the applied experimental conditions.

  14. The advanced liquid metal reactor actinide recycle system

    The current U.S. National Energy Strategy includes four key goals for nuclear policy: enhance safety and design standards, reduce economic risk, reduce regulatory risk, and establish an effective high-level nuclear waste program. The U.S. Department of Energy's Advanced Liquid Metal Reactor Actinide Recycle System is consistent with these objectives. The system has the ability to fulfill multiple missions with the same basic design concept. In addition to providing an option for long-term energy security, the system can be effectively utilized for recycling of actinides in light water reactor (LWR) spent fuel, provide waste management flexibility, including the reduction in the waste quantity and storage time and utilization of the available energy potential of LWR spent fuel. The actinide recycle system is comprised of (1) a compact liquid metal (sodium) cooled reactor system with optimized passive safety characteristics, and (2) pyrometallurgical metal fuel cycle presently under development of Argonne National Laboratory. The waste reduction of LWR spent fuel is accomplished by transmutation or fissioning of the longer-lived transuranic isotopes to shorter-lived fission products in the reactor. In this presentation the economical and environmental incentive of the actinide recycle system is addressed and the status of development including licensing aspects is described. 3 refs., 1 tab., 6 figs

  15. Potential radiation dose from eating fish exposed to actinide contamination

    The purpose of this work is to establish a maximum potential for transporting actinides to man via fish consumption. The study took place in U-pond, a nuclear waste pond on the Hanford Site. It has concentrations of 238U, 238Pu, sup(239,240)Pu and 241Am that are approx. 3 orders of magnitude greater than background levels. Fish living in the pond contain higher actinide concentrations than those observed in fish from any other location. Experiments were performed in U-Pond to determine maximum quantities of actinides that could accumulate in fillets and whole bodies of two centrarchid fish species. Doses to hypothetical consumers were then estimated. Results indicate that highest concentrations occurring in bluegill or bass muscle after more than a year's exposure to the pond would not be sufficient to produce a significant radiation dose to a human consumer, even if he ate 0.5 kg (of the order of 1 lb) of these fillets every day for 70 yr. Natural predators (heron or coyote), having lifetime diets of whole fish from U-Pond, would receive less radiation dose from the ingested actinides than from natural background sources. (author)

  16. Potential radiation dose from eating fish exposed to actinide contamination

    Emery, R.M.; Klopfer, D.C.; Baker, D.A.; Soldat, J.K. (Battelle Pacific Northwest Labs., Richland, WA (USA))

    1981-04-01

    The purpose of this work is to establish a maximum potential for transporting actinides to man via fish consumption. The study took place in U-pond, a nuclear waste pond on the Hanford Site. It has concentrations of /sup 238/U, /sup 238/Pu, sup(239,240)Pu and /sup 241/Am that are approx. 3 orders of magnitude greater than background levels. Fish living in the pond contain higher actinide concentrations than those observed in fish from any other location. Experiments were performed in U-Pond to determine maximum quantities of actinides that could accumulate in fillets and whole bodies of two centrarchid fish species. Doses to hypothetical consumers were then estimated. Results indicate that highest concentrations occurring in bluegill or bass muscle after more than a year's exposure to the pond would not be sufficient to produce a significant radiation dose to a human consumer, even if he ate 0.5 kg (of the order of 1 lb) of these fillets every day for 70 yr. Natural predators (heron or coyote), having lifetime diets of whole fish from U-Pond, would receive less radiation dose from the ingested actinides than from natural background sources.

  17. Review of the sorption of actinides on natural minerals

    Over the past few years, a large body of data concerning sorption of actinides on geologic media has been built in connection with high-level-waste disposal. The primary aim of the work has been to allow predictions of the migration behavior of these radionuclides in the case of a breach of the repository that allowed groundwater flow through the repository. As a result of this work, some new backfill materials specifically tailored for the actinides have also been designed. Several major mechanisms of sorption that appear to dominate the sorption of actinides have emerged from these studies. These mechanisms can be divided into solution reactions dominated by hydrolysis, chemisorption reactions, and oxidation-reduction reactions. Each of these mechanisms will be discussed in detail, with experimental examples. Surprisingly, one mechanism, cation exchange, does not play an important role; why it fails to operate in any significant way in the environmental pH region will be discussed. The implications of the sorption mechanisms for waste forms and backfill materials will be discussed in detail. These discussions will center primarily around the valence state of the actinide in various waste forms and the effect of various anions on leachability from waste forms and backfill materials

  18. Chemistry of actinides and fission products

    This task is concerned primarily with the fundamental chemistry of the actinide and fission product elements. Special efforts are made to develop research programs in collaboration with researchers at universities and in industry who have need of national laboratory facilities. Specific areas currently under investigation include: (1) spectroscopy and photochemistry of actinides in low-temperature matrices; (2) small-angle scattering studies of hydrous actinide and fission product polymers in aqueous and nonaqueous solvents; (3) kinetic and thermodynamic studies of complexation reactions in aqueous and nonaqueous solutions; and (4) the development of inorganic ion exchange materials for actinide and lanthanide separations. Recent results from work in these areas are summarized here

  19. Long-term plant availability of actinides

    Environmental releases of actinide elements raise issues about which data are very limited. Quantitative information is required to assess the long-term behavior of actinides and their potential hazards resulting from the transport through food chains leading to man. Of special interest is the effect of time on the changes in the availability of actinide elements for uptake by plants from soil. This study provides valuable information on the effects of weathering and aging on the uptake of actinides from soil by range and crop plants grown under realistic field conditions

  20. Hysteresis in Carbon Nanotube Transistors: Measurement and Analysis of Trap Density, Energy Level, and Spatial Distribution.

    Park, Rebecca Sejung; Shulaker, Max Marcel; Hills, Gage; Suriyasena Liyanage, Luckshitha; Lee, Seunghyun; Tang, Alvin; Mitra, Subhasish; Wong, H-S Philip

    2016-04-26

    We present a measurement technique, which we call the Pulsed Time-Domain Measurement, for characterizing hysteresis in carbon nanotube field-effect transistors, and demonstrate its applicability for a broad range of 1D and 2D nanomaterials beyond carbon nanotubes. The Pulsed Time-Domain Measurement enables the quantification (density, energy level, and spatial distribution) of charged traps responsible for hysteresis. A physics-based model of the charge trapping process for a carbon nanotube field-effect transistor is presented and experimentally validated using the Pulsed Time-Domain Measurement. Leveraging this model, we discover a source of traps (surface traps) unique to devices with low-dimensional channels such as carbon nanotubes and nanowires (beyond interface traps which exist in today's silicon field-effect transistors). The different charge trapping mechanisms for interface traps and surface traps are studied based on their temperature dependencies. Through these advances, we are able to quantify the interface trap density for carbon nanotube field-effect transistors (∼3 × 10(13) cm(-2) eV(-1) near midgap), and compare this against a range of previously studied dielectric/semiconductor interfaces. PMID:27002483

  1. Nuclear level density formula with energy-dependent shell and pairing corrections

    A new phenomenological level density formula is based on the analytical expression of the single-particle state density. The main features of the proposed formula is the existence of not only the excitation-dependent shell correction energy but also the excitation-dependent pairing correction with the shell-pairing correlations (thus called SPC model), so far considered only by means of the microscopic Fermi-gas model, and no need of independent shell and pairing correction energy tables as often used for the previous formulas. At the ground states the shell and pairing corrections with the shell-pairing correlation terms are computed by using 6 constants for each shell, values of which are determined as to fit the empirical mass excess data. The analyses by using the observed s-wave neutron and proton resonance spacings of the mass range A=41-67 show that the prediction of the SPC model and its parameters will be superior to those of the previous models of the traditional Fermi-gas. This improvement seems to be due to the prescriptions of the excitation-dependent correction energies both for the shell and for the pairing effects. (author)

  2. [Composition and Density of Soil Fauna in the Region with Enhanced Radioactivity Level (Komi Republic, Vodnyi)].

    Kolesnikova, A A; Kudrin, A A; Konakova, T N; Taskaeva, A A

    2015-01-01

    Studies on the influence of high levels of radiation on soil fauna were carried out in 2012 in the territory formed as a result of the activity of the enterprise for extraction and production of radium from reservoir water and waste of uranium ore from 1931 to 1956. At present the local radioactive pollution in this area is caused by the presence of heavy natural radionuclides 226Ra, 238U and products of their disintegration in soils. The oppression of soil invertebrate.fauna in pine forests and meadows with high levels of radionuclides and heavy metals is revealed. Also shown is the decrease in the number and density of different taxonomic groups of invertebrates, reduction of the diversity and spectrum of trophic groups and vital forms in the area with a high content of radionuclides in soil. Our results are in agreement with the results obtained by the similar studies showing negative influence of high-level ionizing radiation on soil fauna. PMID:26310020

  3. Estimation of loading density of underground well repositories for solid high-level radioactive wastes

    Malkovsky, V. I.; Pek, A. A.

    2007-06-01

    The convective transfer of radionuclides by subsurface water from a geological repository of solidified high-level radioactive wastes (HLW) is considered. The repository is a cluster of wells of large diameter with HLW disposed of in the lower portions of the wells. The safe distance between wells as a function of rock properties and parameters of well loading with wastes has been estimated from mathematical modeling. A maximum permissible concentration of radionuclides in subsurface water near the ground surface above the repository is regarded as a necessary condition of safety. The estimates obtained show that well repositories allow for a higher density of solid HLW disposal than shaft storage facilities. Advantages and disadvantages of both types of storage facilities are considered in order to estimate the prospects for their use for underground disposal of solid HLW.

  4. Density-matrix renormalization group algorithm with multi-level active space

    Ma, Yingjin; Wen, Jing; Ma, Haibo

    2015-07-01

    The density-matrix renormalization group (DMRG) method, which can deal with a large active space composed of tens of orbitals, is nowadays widely used as an efficient addition to traditional complete active space (CAS)-based approaches. In this paper, we present the DMRG algorithm with a multi-level (ML) control of the active space based on chemical intuition-based hierarchical orbital ordering, which is called as ML-DMRG with its self-consistent field (SCF) variant ML-DMRG-SCF. Ground and excited state calculations of H2O, N2, indole, and Cr2 with comparisons to DMRG references using fixed number of kept states (M) illustrate that ML-type DMRG calculations can obtain noticeable efficiency gains. It is also shown that the orbital re-ordering based on hierarchical multiple active subspaces may be beneficial for reducing computational time for not only ML-DMRG calculations but also DMRG ones with fixed M values.

  5. Cleanup of hydrochloric acid waste streams from actinide processes using extraction chromatography

    Extraction chromatography is under development as a method to lower actinide activity levels in hydrochloric acid (HCl) effluent steams. Successful application of this technique would allow recycle of the largest portion of HCl, while lowering the quantity and improving the form of solid waste generated. The extraction of plutonium and americium from HCl solutions was examined for several commercial and similar laboratory-produced resins coated with n-octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) and either tributyl phosphate (TBP), or diamyl amylphosphonate (DAAP). Distribution coefficients for Pu and Am were measured by contact studies in 1-10 M HCl, while varying REDOX conditions, actinide loading levels, and contact time intervals. Significant differences in the actinide distribution coefficients, and in the kinetics of actinide removal were observed as a function of resin formulation

  6. Physical Activity Level of Post-menopausal Women with Low Bone Mineral Density.

    Dallanezi, Glauber; Freire, Beatriz Funayama Alvarenga; Nahás, Eliana Aguiar Petri; Nahás-Neto, Jorge; Corrente, José Eduardo; Mazeto, Gláucia Maria Ferreira da Silva

    2016-05-01

    Introduction Proper physical activity is related to the prevention and the treatment of osteoporosis. Purpose To assess the level of physical activity (PA) in post-menopausal women with low bone mineral density (BMD). Methods This cross-sectional clinical study included 123 post-menopausal women. The inclusion criteria were: age of ≥ 45 years with last menses at least 12 months prior to the initiation of the study, and bone density scan (BDS) values measured over the preceding 12 months. Women with severe osteoarthritis were excluded. Women were allocated into three groups, according to BMD measured by BDS [osteoporosis (OP; 54 women), osteopenia (35 women), and normal bone density (NBD; 35 women)], and compared for general, clinical, and anthropometric data, and for PA level. The latter was assessed using the International Physical Activity Questionnaire (IPAQ), in metabolic equivalent of task (MET) units. Participants were classified as sedentary, active or very active. Quantitative variables were compared using ANOVA followed by Tukey's test. Associations between qualitative variables were tested by Chi-square (χ2) or Fisher's exact test. In order to check for differences among groups and IPAQ domains, a generalized linear model with Gamma distribution was adjusted for values in METs. Results The OP group differed from the NBD group regarding age (61.8 ± 10.1 and 52.9 ± 5.4 years), percentage of participants with self-declared white ethnicity (43.9 and 28.0%), body mass index (BMI - 25.7 ± 5.4 and 30.9 ± 5.1 kg/m(2)), and time since menopause (15.5 ± 7.5 and 5.8 ± 4.5 years). Smoking rates were higher in the OP (55.6%) and NBD groups (33.3%) than in the osteopenia group (11.1%). Within the OP group, the rate of subjects with sedentary lifestyles was higher (42.6%), and time spent sitting was greater (344.3 ± 204.8 METs) than in the groups with osteopenia (20.0% and 300.9 ± 230.6 METs) and NBD (17.7% and 303

  7. Effects of maximal doses of atorvastatin versus rosuvastatin on small dense low-density lipoprotein cholesterol levels

    Maximal doses of atorvastatin and rosuvastatin are highly effective in lowering low-density lipoprotein (LDL) cholesterol and triglyceride levels; however, rosuvastatin has been shown to be significantly more effective than atorvastatin in lowering LDL cholesterol and in increasing high-density lipo...

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

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

    2016-05-01

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

  9. Effect of planting methods, seed density and nitrogen phosphorus (NP) fertilizer levels on sweet corn (Zea maYs L.)

    A field experiment was conducted to evaluate the effect of planting methods, seed density and nitrogen phosphorus (NP) fertilizer levels on emergence m/sup -2/ growth and grain yield of sweet corn. The fertilizer and interaction of fertilizer x seed density had significant negative effect with increasing level while seed density had a positive effect with increased density on emergence per m/sup 2/. Increased seed density significantly reduced plant growth which increased with application of higher fertilizer dose. The grain yield was improves by ridge planting methods, increased seed density and increased fertilizer levels. The highest grain yield (3,553.50 kg ha/sup-1/) of sweet corn plants was recorded in ridge planting method with highest NP fertilizer level of 300:150 kg ha/sup 1/ and 4 seeds hill/sup -1/. The lowest grain yield (3,493.75 kg ha/sup -1/) of sweet corn was observed in flat sowing planting method with 120:75 NP level and 2 seeds hill/sup -1/ seed density. The ridge planting rank first then furrow and flat planting methods on basis of grain yield per hectare. The sweet corn plant yield was high with 4 seeds hill/sup -1/ compared with 2 seeds hill/sup -1/. (author)

  10. Extraction studies on the partitioning of actinides from HLW

    TRUEX process uses Octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) for the partitioning of actinides from acidic waste. CMPO is one of the most effective organophosphorus compounds. CMPO has drawbacks like third phase formation. A two-step process is developed using TBP and CMPO as extractants. The first step of the proposed process is a 'uranium depletion step' in which uranium in HLW is removed using 30% TBP in n-dodecane. Neptunium and plutonium, extracted in TBP, are recovered using a mixture of hydrogen peroxide (0.25 M) and ascorbic acid (0.05 M) in 2.0 M nitric acid medium. Neptunium and plutonium are reduced to Np(V) and Pu(III). Americium and curium as well as traces of uranium, neptunium and plutonium are partitioned in the second step. The separation of neptunium and plutonium from large quantities of uranium from loaded TBP will simplify their further separation. Use of citrate containing buffer solution for the recovery of actinides extracted in CMPO-TBP phase eliminates the problem of reflux of americium. This reduces the generation of secondary wastes. The process has been standardised based on the data generated in the batch and counter-current studies. Solvent extraction studies have also been carried out using a mixture of di-(2-ethylhexyl)phosphoric acid (HDEHP) and CMPO in n-paraffin. It is seen that the actinides can be extracted even from solutions of HLW at high acid concentration of 3 M using the mixed extractant. Plutonium is also stripped along with the trivalent actinides. This mixed solvent may find useful applications in the partitioning of actinides from waste solutions. Supported liquid membrane (SLM) technique for partitioning of actinides from high level waste of PUREX origin uses solution of CMPO in n-dodecane with polytetrafluoroethylene support and a mixture of citric acid, formic acid and hydrazine hydrate as a receiving phase. Studies indicated good transport of actinides across the membrane from nitric acid

  11. Radiochemical separation of actinides for their determination in environmental samples and waste products

    Gleisberg, B. [Nuclear Engineering and Analytics Rossendorf, Inc. (VKTA), Dresden (Germany)

    1997-03-01

    The determination of low level activities of actinides in environmental samples and waste products makes high demands on radiochemical separation methods. Artificial and natural actinides were analyzed in samples form the surrounding areas of NPP and of uranium mines, incorporation samples, solutions containing radioactive fuel, solutions and solids resutling from the process, and in wastes. The activities are measured by {alpha}-spectrometry and {gamma}-spectrometry. (DG)

  12. SACSESS – the EURATOM FP7 project on actinide separation from spent nuclear fuels

    Bourg Stéphane; Geist Andreas; Narbutt Jerzy

    2015-01-01

    Recycling of actinides by their separation from spent nuclear fuel, followed by transmutation in fast neutron reactors of Generation IV, is considered the most promising strategy for nuclear waste management. Closing the fuel cycle and burning long-lived actinides allows optimizing the use of natural resources and minimizing the long-term hazard of high-level nuclear waste. Moreover, improving the safety and sustainability of nuclear power worldwide. This paper presents the activities strivin...

  13. Highly absorptive curcumin reduces serum atherosclerotic low-density lipoprotein levels in patients with mild COPD

    Funamoto M

    2016-08-01

    and hemoglobin A1c and LDL-cholesterol, triglyceride, or high-density lipoprotein-cholesterol levels after treatment were similar for the two groups. However, the percent change in the AT-LDL level was significantly (P=0.020 lower in the Theracurmin® group compared with the placebo group.Conclusion: Theracurmin® reduced levels of atherosclerotic AT-LDL, which may lead to the prevention of future cardiovascular events in mild COPD subjects. Keywords: curcumin, AT-LDL, COPD, atherosclerosis

  14. Using Correlations to Understand Changes in Actinide Bonding

    An important issue in actinide science is the changing role of the 5f electrons, both when progressing across the series, as well as how experimental variables affect these roles in a particular element's chemistries and physics. The function of these 5f electrons can be changed by experimental conditions: temperature and pressure being two of many such variables. The 5f electrons of several actinide metals, their alloys and compounds are affected greatly by pressure, due to the very large decreases in interatomic distances encountered under pressure. The latter bring about significant changes in the total energy of the system and in the electronic energy levels, which in turn affect the potential for overlap/hybridization) of their orbitals, promotion of electrons to other orbitals, etc. The physical state, temperature, pressure, specific structures, magnetic interactions and spin polarization effects are all critical parameters for bonding. Often correlations of behavior with these parameters can provide unique insights and understanding into the bonding and the changes that occur in it. With the advancement of modern computation approaches using FPMTO, or other approaches, theory has enlightened greatly the understanding of not only the bonding behavior of these elements but also the understanding of changes observed experimentally. But these computational efforts have some complications and limitations, and at times experimental findings and theory are not always in full agreement. In contrast to the behaviors of the elements, changes observed with compounds often are not be linked directly to the involvement of 5f electrons, due in part to the presence and bonding role of non-actinide atoms. The latter affect both the actinide interatomic distances and the type of electronic orbitals that interact. Presented here is an overview of the pressure behavior several actinide elements, some insights into the bonding behavior of compounds under pressure and selected

  15. Genetically elevated apolipoprotein A-I, high-density lipoprotein cholesterol levels, and risk of ischemic heart disease

    Lundegaard, Christiane; Tybjærg-Hansen, Anne; Grande, Peer;

    2010-01-01

    Epidemiologically, levels of high-density lipoprotein (HDL) cholesterol and its major protein constituent, apolipoprotein A-I (apoA-I), are inversely related to risk of ischemic heart disease (IHD).......Epidemiologically, levels of high-density lipoprotein (HDL) cholesterol and its major protein constituent, apolipoprotein A-I (apoA-I), are inversely related to risk of ischemic heart disease (IHD)....

  16. HERMES: a personal-computer program for calculation of the Fermi-Gas Model parameters of nuclear level density

    A computer program, HERMES, that provides the quantities usually needed in nuclear level density calculations, has been developed. The applied model is the standard Fermi Gas Model (FGM) in which pairing correlations and shell effects are opportunely taken into account. The effects of additional nuclear structure properties together with their inclusion into the computer program are also considered. Using HERMES, a level density parameter systematics has been constructed for mass range 41 ≤ A ≤ 253. (author)

  17. Combining enhanced biomass density with reduced lignin level for improved forage quality.

    Gallego-Giraldo, Lina; Shadle, Gail; Shen, Hui; Barros-Rios, Jaime; Fresquet Corrales, Sandra; Wang, Huanzhong; Dixon, Richard A

    2016-03-01

    To generate a forage crop with increased biomass density that retains forage quality, we have genetically transformed lines of alfalfa (Medicago sativa L.) expressing antisense constructs targeting two different lignin pathway biosynthetic genes with a construct for down-regulation of a WRKY family transcription factor that acts as a repressor of secondary cell wall formation in pith tissues. Plants with low-level expression of the WRKY dominant repressor construct produced lignified cell walls in pith tissues and exhibited enhanced biomass and biomass density, with an increase in total sugars in the cell wall fraction; however, lines with high expression of the WRKY dominant repressor construct exhibited a very different phenotype, with loss of interfascicular fibres associated with repression of the NST1 transcription factor. This latter phenotype was not observed in transgenic lines in which the WRKY transcription factor was down-regulated by RNA interference. Enhanced and/or ectopic deposition of secondary cell walls was also seen in corn and switchgrass expressing WRKY dominant repressor constructs, with enhanced biomass in corn but reduced biomass in switchgrass. Neutral detergent fibre digestibility was not impacted by WRKY expression in corn. Cell walls from WRKY-DR-expressing alfalfa plants with enhanced secondary cell wall formation exhibited increased sugar release efficiency, and WRKY dominant repressor expression further increased sugar release in alfalfa down-regulated in the COMT, but not the HCT, genes of lignin biosynthesis. These results suggest that significant enhancements in forage biomass and quality can be achieved through engineering WRKY transcription factors in both monocots and dicots. PMID:26190611

  18. Assessment of Growth and Oxidized High-Density Lipoprotien Level in Children on Regular Hemodialysis

    Soheir Bahgat Fayed*, Manal Abd EL-Salam*, Iman Mouhamed El-Bagoury**,

    2013-04-01

    Full Text Available Background: The cause of growth failure in chronic kidney disease (CKD is multi-factorial with linear impairment being a final common pathway of various factors including malnutrition, increased catabolism, loss of nutrients and antioxidants, and aggressive dietary restrictions during dialysis .Anemia, metabolic acidosis and persistent micro inflammations are also causative factors.Objectives: To assess growth in children with CKD on regular hemodialysis and measure oxidized high density lipoprotein (OX-HDL, highly sensitive C-reactive protein (hsCRP and to discuss their roles as a risk factors of malnutrition among studied cases.Patients and Methods: The study included 25 children with end stage renal disease (ESRD on regular hemodialysis more than 6 months. Their ages ranged from 5-15 years with a mean of 10.76 years, also 25 of apparently healthy, age and sex matched were included. The study sample was selected from pediatric dialysis unit and outpatients clinic, of AL-Zahraa University hospital .Anthropometric measurements were assessed with determination of OX-HDL and hsCRP serum levels in both cases and the controls.Results: Anthropometry showed significant decrease in weight, height, body mass index, mid arm circumference and triceps skin fold thickness in patients when compared to the controls. 100% of patients had high level of OX-HDL and hsCRP, and positive correlation between OX-HDL and Z-score for Wt and Ht were detected.Conclusion: Malnutrition, and growth delay are common in children with chronic kidney disease on regular hemodialysis. High rate of inflammation in dialysis children as there were high level of hsCRP and OX HDL. HDL, in regular hemodialysis children loses its protective function as an anti-oxidant, anti-inflammatory and becomes pro-inflammatory factor

  19. Peptide YY (PYY) Levels and Bone Mineral Density (BMD) in Women with Anorexia Nervosa

    Utz, Andrea L.; Lawson, Elizabeth A.; Misra, Madhusmita; Mickley, Diane; Gleysteen, Suzanne; Herzog, David B.; Klibanski, Anne; Miller, Karen K.

    2008-01-01

    Introduction Anorexia nervosa is a psychiatric illness that results in significant bone loss. Studies examining the neuroendocrine dysregulation that occurs in AN may increase understanding of endocrine systems that regulate bone mass. PYY is an anorexigenic peptide derived primarily from the intestine, with actions mediated via activation of Y-receptors. We have previously shown that PYY levels are elevated in adolescents with AN. Y2 receptor knockout mice have increased bone mineral density (BMD) and thus PYY may play a role in regulating bone mass. We hypothesized that PYY levels would be inversely associated with BMD in women with AN. Methods This was a cross-sectional study performed in a General Clinical Research Center of 12 adult women with AN, (mean ± SEM) mean age 30.9 ± 1.8 years, BMI 17.1 ± 0.4 kg/m2, and % ideal body weight 77.5 ± 1.7%. PYY concentrations were measured hourly from 20:00 h to 08:00 h. BMD was measured using dual x-ray absorptiometry (DXA). Results In women with AN, mean overnight PYY levels strongly inversely correlated with BMD at the PA spine (r = −0.77, p = 0.003), lateral spine (r = −0.82, p = 0.002), total hip (r = −0.75, p = 0.005), femoral neck (r = −0.72, p = 0.009), total radius (r = −0.72, p = 0.009) and 1/3 distal radius (r = −0.81, p = 0.002). Body mass index was inversely correlated with PYY level (r = −0.64, p = 0.03). Multivariate stepwise regression analysis was performed to determine the contribution of age, duration of AN, BMI, fat-free mass, and PYY to BMD. For PA and lateral spine, PYY was the primary determinant of BMD, accounting for 59% and 67% of the variability, respectively. Fat-free mass and duration of anorexia nervosa were the primary determinants of BMD at other skeletal sites. Conclusions In women with anorexia nervosa, an elevated PYY level is strongly associated with diminished BMD, particularly at the spine. Therefore further investigation of the hypothesis that PYY may contribute to

  20. Calculated Atomic Volumes of the Actinide Metals

    Skriver, H.; Andersen, O. K.; Johansson, B.

    1979-01-01

    The equilibrium atomic volume is calculated for the actinide metals. It is possible to account for the localization of the 5f electrons taking place in americium.......The equilibrium atomic volume is calculated for the actinide metals. It is possible to account for the localization of the 5f electrons taking place in americium....

  1. Environmental chemistry of the actinide elements

    The environmental chemistry of the actinide elements is a new branch of science developing with the application of nuclear energy on a larger and larger scale. Various aspects of the environmental chemistry of the actinide elements are briefly reviewed in this paper, such as its significance in the nuclear waste disposal, its coverage of research fields and possible directions for future study

  2. PIE analysis for minor actinide

    Minor actinide (MA) is generated in nuclear fuel during the operation of power reactor. For fuel design, reactivity decrease due to it should be considered. Out of reactors, MA plays key role to define the property of spent fuel (SF) such as α-radioactivity, neutron emission rate, and criticality of SF. In order to evaluate the calculation codes and libraries for predicting the amount of MA, comparison between calculation results and experimentally obtained data has been conducted. In this report, we will present the status of PIE data of MA taken by post irradiation examinations (PIE) and several calculation results. (author)

  3. Study on the relationship between serum testosterone level and forearm distal bone density in post-menopausal women

    Objective: To study the relationship between the androgen level and bone density in post-menopausal women. Methods: Serum testosterone (T) level and forearm distal bone density (BMD) were measured in 39 past-menopausal women who had never taken any estrogen or calcium preparation. Their serum estradiol (E2) levels were about the same. According to their BMD, the 39 subjects were divided into normal (n = 22) and osteoporotic (n = 17) groups. Results: The mean serum testosterone (T) level in the normal group was significantly higher than that in the osteoporotic group (p 1 = 0.72, r20.75; p 1 and r2 was 0.14, suggesting similarity of the positive cor-relationship for both groups (p > 0.05). Conclusion: Serum testosterone level seems to bear close relationship with bone density and osteoporosis

  4. Actinide co-conversion by internal gelation

    Suitable microstructures and homogenous microspheres of actinide compounds are of interest for future nuclear fuel or transmutation target concepts to prevent the generation and dispersal of actinide powder. Sol-gel routes are being investigated as one of the possible solutions for producing these compounds. Preliminary work is described involving internal gelation to synthesize mixed compounds including minor actinides, particularly mixed actinide or mixed actinide-inert element compounds. A parameter study is discussed to highlight the importance of the initial broth composition for obtaining gel microspheres without major defects (cracks, craters, etc.). In particular, conditions are defined to produce gel beads from Zr(IV)/Y(III)/Ce(III) or Zr(IV)/An(III) systems. After gelation, the heat treatment of these microspheres is described for the purpose of better understanding the formation of cracks after calcination and verifying the effective synthesis of an oxide solid-solution. (authors)

  5. Actinide ion sensor for pyroprocess monitoring

    Jue, Jan-fong; Li, Shelly X.

    2014-06-03

    An apparatus for real-time, in-situ monitoring of actinide ion concentrations which comprises a working electrode, a reference electrode, a container, a working electrolyte, a separator, a reference electrolyte, and a voltmeter. The container holds the working electrolyte. The voltmeter is electrically connected to the working electrode and the reference electrode and measures the voltage between those electrodes. The working electrode contacts the working electrolyte. The working electrolyte comprises an actinide ion of interest. The reference electrode contacts the reference electrolyte. The reference electrolyte is separated from the working electrolyte by the separator. The separator contacts both the working electrolyte and the reference electrolyte. The separator is ionically conductive to the actinide ion of interest. The reference electrolyte comprises a known concentration of the actinide ion of interest. The separator comprises a beta double prime alumina exchanged with the actinide ion of interest.

  6. SACSESS – the EURATOM FP7 project on actinide separation from spent nuclear fuels

    Bourg Stéphane

    2015-12-01

    Full Text Available Recycling of actinides by their separation from spent nuclear fuel, followed by transmutation in fast neutron reactors of Generation IV, is considered the most promising strategy for nuclear waste management. Closing the fuel cycle and burning long-lived actinides allows optimizing the use of natural resources and minimizing the long-term hazard of high-level nuclear waste. Moreover, improving the safety and sustainability of nuclear power worldwide. This paper presents the activities striving to meet these challenges, carried out under the Euratom FP7 collaborative project SACSESS (Safety of Actinide Separation Processes. Emphasis is put on the safety issues of fuel reprocessing and waste storage. Two types of actinide separation processes, hydrometallurgical and pyrometallurgical, are considered, as well as related aspects of material studies, process modeling and the radiolytic stability of solvent extraction systems. Education and training of young researchers in nuclear chemistry is of particular importance for further development of this field.

  7. Pyrometallurgical processes for recovery of actinide elements

    Battles, J.E.; Laidler, J.J.; McPheeters, C.C.; Miller, W.E.

    1994-01-01

    A metallic fuel alloy, nominally U-20-Pu-lOZr, is the key element of the Integral Fast Reactor (IFR) fuel cycle. Metallic fuel permits the use of an innovative, simple pyrometallurgical process, known as pyroprocessing, (the subject of this report), which features fused salt electrorefining of the spent fuel. Electrorefining separates the actinide elements from fission products, without producing a separate stream of plutonium. The plutonium-bearing product is contaminated with higher actinides and with a minor amount of rare earth fission products, making it diversion resistant while still suitable as a fuel material in the fast spectrum of the IFR core. The engineering-scale demonstration of this process will be conducted in the refurbished EBR-II Fuel Cycle Facility, which has entered the start-up phase. An additional pyrometallurgical process is under development for extracting transuranic (TRU) elements from Light Water Reactor (LWR) spent fuel in a form suitable for use as a feed to the IFR fuel cycle. Four candidate extraction processes have been investigated and shown to be chemically feasible. The main steps in each process are oxide reduction with calcium or lithium, regeneration of the reductant and recycle of the salt, and separation of the TRU product from the bulk uranium. Two processes, referred to as the lithium and salt transport (calcium reductant) processes, have been selected for engineering-scale demonstration, which is expected to start in late 1993. An integral part of pyroprocessing development is the treatment and packaging of high-level waste materials arising from the operations, along with the qualification of these waste forms for disposal in a geologic repository.

  8. Pyrometallurgical processes for recovery of actinide elements

    A metallic fuel alloy, nominally U-20-Pu-lOZr, is the key element of the Integral Fast Reactor (IFR) fuel cycle. Metallic fuel permits the use of an innovative, simple pyrometallurgical process, known as pyroprocessing, (the subject of this report), which features fused salt electrorefining of the spent fuel. Electrorefining separates the actinide elements from fission products, without producing a separate stream of plutonium. The plutonium-bearing product is contaminated with higher actinides and with a minor amount of rare earth fission products, making it diversion resistant while still suitable as a fuel material in the fast spectrum of the IFR core. The engineering-scale demonstration of this process will be conducted in the refurbished EBR-II Fuel Cycle Facility, which has entered the start-up phase. An additional pyrometallurgical process is under development for extracting transuranic (TRU) elements from Light Water Reactor (LWR) spent fuel in a form suitable for use as a feed to the IFR fuel cycle. Four candidate extraction processes have been investigated and shown to be chemically feasible. The main steps in each process are oxide reduction with calcium or lithium, regeneration of the reductant and recycle of the salt, and separation of the TRU product from the bulk uranium. Two processes, referred to as the lithium and salt transport (calcium reductant) processes, have been selected for engineering-scale demonstration, which is expected to start in late 1993. An integral part of pyroprocessing development is the treatment and packaging of high-level waste materials arising from the operations, along with the qualification of these waste forms for disposal in a geologic repository

  9. Gold Nanocrystal Labeling Allows Low Density Lipoprotein Imaging From The Subcellular To Macroscopic Level

    Allijn, Iris E.; Leong, Wei; Tang, Jun; Gianella, Anita; Mieszawska, Aneta J.; Fay, Francois; Ma, Ge; Russell, Stewart; Callo, Catherine B.; Gordon, Ronald E.; Korkmaz, Emine; Post, Jan Andries; Zhao, Yiming; Gerritsen, Hans C.; Thran, Axel; Proksa, Roland; Daerr, Heiner; Storm, Gert; Fuster, Valentin; Fisher, Edward A.; Fayad, Zahi A.; Mulder, Willem J.M.

    2013-01-01

    Low density lipoprotein (LDL) plays a critical role in cholesterol transport and is closely linked to the progression of several diseases. This motivates the development of methods to study LDL behavior from the microscopic to whole-body level. We have developed an approach to efficiently load LDL with a range of diagnostically active nanocrystals or hydrophobic agents. We performed focused experiments on LDL labeled with gold nanocrystals (Au-LDL). The labeling procedure had minimal effect on LDL size, morphology or composition. Biological function was found to be maintained from both in vitro and in vivo experiments. Tumor bearing mice were injected intravenously with LDL, DiR-LDL, Au-LDL or a gold-loaded nanoemulsion. LDL accumulation in the tumors was detected with whole body imaging methods, such as computed tomography (CT), spectral CT and fluorescence imaging. Cellular localization was studied with transmission electron microscopy (TEM) and fluorescence techniques. In conclusion, this LDL labeling procedure should permit the study of lipoprotein biointeractions in unprecedented detail. PMID:24127782

  10. Reduction of minor actinides for recycling in a light water reactor

    The aim of actinide transmutation from spent nuclear fuel is the reduction in mass of high-level waste which must be stored in geological repositories and the lifetime of high-level waste; these two achievements will reduce the number of repositories needed, as well as the duration of storage. The present work is directed towards the evaluation of an advanced nuclear fuel cycle in which the minor actinides (Np, Am and Cm) could be recycled to remove most of the radioactive material; a reference of actinides production in standard nuclear fuel of uranium at the end of its burning in a BWR is first established, after a design of fuel rod containing 6% of minor actinides in a matrix of uranium from the enrichment lines is proposed, then 4 fuel rods of standard uranium are replaced by 4 actinides bars to evaluate the production and transmutation of them and finally the minor actinides reduction in the fuel is evaluated. In the development of this work the calculation tool are the codes: Intrepin-3, Casmo-4 and Simulate-3. (Author)

  11. Negative energy densities in integrable quantum field theories at one-particle level

    Bostelmann, Henning

    2015-01-01

    We study the phenomenon of negative energy densities in quantum field theories with self-interaction. Specifically, we consider a class of integrable models (including the sinh-Gordon model) in which we investigate the expectation value of the energy density in one-particle states. In this situation, we classify the possible form of the stress-energy tensor from first principles. We show that one-particle states with negative energy density generically exist in non-free situations, and we establish lower bounds for the energy density (quantum energy inequalities). Demanding that these inequalities hold reduces the ambiguity in the stress-energy tensor, in some situations fixing it uniquely. Numerical results for the lowest spectral value of the energy density allow us to demonstrate how negative energy densities depend on the coupling constant and on other model parameters.

  12. Electrochemical decontamination system for actinide processing gloveboxes

    Wedman, D.E.; Lugo, J.L.; Ford, D.K.; Nelson, T.O.; Trujillo, V.L.; Martinez, H.E.

    1998-03-01

    An electrolytic decontamination technology has been developed and successfully demonstrated at Los Alamos National Laboratory (LANL) for the decontamination of actinide processing gloveboxes. The technique decontaminates the interior surfaces of stainless steel gloveboxes utilizing a process similar to electropolishing. The decontamination device is compact and transportable allowing it to be placed entirely within the glovebox line. In this way, decontamination does not require the operator to wear any additional personal protective equipment and there is no need for additional air handling or containment systems. Decontamination prior to glovebox decommissioning reduces the potential for worker exposure and environmental releases during the decommissioning, transport, and size reduction procedures which follow. The goal of this effort is to reduce contamination levels of alpha emitting nuclides for a resultant reduction in waste level category from High Level Transuranic (TRU) to low Specific Activity (LSA, less than or equal 100 nCi/g). This reduction in category results in a 95% reduction in disposal and disposition costs for the decontaminated gloveboxes. The resulting contamination levels following decontamination by this method are generally five orders of magnitude below the LSA specification. Additionally, the sodium sulfate based electrolyte utilized in the process is fully recyclable which results in the minimum of secondary waste. The process bas been implemented on seven gloveboxes within LANL`s Plutonium Facility at Technical Area 55. Of these gloveboxes, two have been discarded as low level waste items and the remaining five have been reused.

  13. The ALMR actinide burning system

    The advanced liquid-metal reactor (ALMR) actinide burning system is being developed under the sponsorship of the US Department of Energy to bring its unique capabilities to fruition for deployment in the early 21st century. The system consists of four major parts: the reactor plant, the metal fuel and its recycle, the processing of light water reactor (LWR) spent fuel to extract the actinides, and the development of a residual waste package. This paper addresses the status and outlook for each of these four major elements. The ALMR is being developed by an industrial group under the leadership of General Electric (GE) in a cost-sharing arrangement with the US Department of Energy. This effort is nearing completion of the advanced conceptual design phase and will enter the preliminary design phase in 1994. The innovative modular reactor design stresses simplicity, economics, reliability, and availability. The design has evolved from GE's PRISM design initiative and has progressed to the final stages of a prelicensing review by the US Nuclear Regulatory Commission (NRC); a safety evaluation report is expected by the end of 1993. All the major issues identified during this review process have been technically resolved. The next design phases will focus on implementation of the basic safety philosophy of passive shutdown to a safe, stable condition, even without scram, and passive decay heat removal. Economic projections to date show that it will be competitive with non- nuclear and advanced LWR nuclear alternatives

  14. Serum vitamin D level and bone mineral density in premenopausal Egyptian women with fibromyalgia.

    Olama, Shereem Mohamed; Senna, Mohammed K; Elarman, Mohammed Mohamed; Elhawary, Galal

    2013-01-01

    Patients with fibromyalgia syndrome (FMS) have impaired mobility and therefore get less sunlight exposure, we postulated that they may be at increased risk of developing osteoporosis (OP). The aim of this study was to assess and compare serum vitamin D level and bone mineral density (BMD) value in patients with primary FMS (PFMS) and healthy controls. A total of 50 patients with PFMS participated in this case-control study, and 50 healthy females who were age-matched to the patients were used as the control group. Venous blood samples collected from all subjects were used to evaluate serum 25-hydroxyvitamin D3 (25-OHD). BMD was measured at the lumbar spine (L2-L4) anteroposterior, femoral neck and forearm by dual-energy X-ray absorptiometry. Patients with PFMS had significantly lower serum 25-OHD than controls (15.1 ± 6.1 and 18.8 ± 5.4 ng/ml, respectively, p = 0.0018). Apart from the BMD in the lumbar spine, which was significantly lower in the PFMS patients compared with controls (p = 0.0012), no significant difference was found in other measures of BMD. Compared to PFMS patients who had serum level of the 25-OHD >20 ng/ml, the patients with 25-OHD ≤20 ng/ml are more likely to have impaired short memory (46.4 vs. 13.6%, respectively, p = 0.0136), confusion (50 vs. 18.2%, respectively, p = 0.0199), mood disturbance (60.7 vs. 27.3%, respectively, p = 0.0185), sleep disturbance (53.6 vs. 22.7%, respectively, p = 0.0271), restless leg syndrome (57.1 vs. 27.3%, respectively, p = 0.0346) and palpitation (67.9 vs. 36.4%, respectively, p = 0.0265). Serum level of the 25-OHD is inversely correlated with visual analogue scale (VAS) of pain (p = 0.016), Beck score for depression (p = 0.020) and BMD at lumbar spine (p = 0.012). The lumbar BMD inversely correlated with VAS of pain (p = 0.013) and Beck score for depression (p = 0.016). This study confirmed high prevalence of hypovitaminosis D among in patients with PFMS. This study confirmed the concept that FMS is a risk

  15. Study on Method of Asphalt Density Measurement Using Low Level Radioactive Isotope

    The fundamental cause of damage to road pavement is insufficient management of asphalt density during construction. Currently, asphalt density in Korea is measured in a laboratory by extracting a core sample after construction. This method delays the overall time of measurement and therefore it is difficult to achieve real-time density management. Using a radioactive isotope for measuring asphalt density during construction reduces measuring time thus enabling realtime measurement. Also, it is provided reliable density measurement to achieve effective density management at work sites. However, existing radiological equipment has not been widely used because of management restrictions and regulations due to the high radiation dose. In this study, we employed a non-destructive method for density measurement. Density is measured by using a portable gamma-ray backscatter device having a radioactivity emission of 100 μCi or less (notice No. 2002-23, Ministry of Science and Technology, standards on radiation protection, etc.), a sealed radioactive source subject to declaration

  16. Intensity and the importance of country level differences: An analysis of the relationship between per capita emissions and population density

    Longden, Thomas

    2015-01-01

    Previous studies have found an inverse (or negative) correlation between urban population density and per capita emissions from land transport. In contrast, this paper finds a positive relationship between per capita CO2 emissions from transport and population density using a dataset of over 200 cities from 28 countries. This positive relationship holds when a range of variables are accounted for and the specification of the regression analysis captures the distinction between country level d...

  17. Vitamin D, parathyroid hormone levels and bone mineral density in community-dwelling older women: The Rancho Bernardo Study

    von Mühlen, Denise G; Greendale, Gail A.; Cedric F Garland; Wan, Lori; Barrett-Connor, Elizabeth

    2005-01-01

    Vitamin D (25(OH)D) increases the efficiency of intestinal calcium absorption. Low levels of serum calcium stimulate the secretion of parathyroid hormone (PTH), which maintains serum calcium levels at the expense of increased bone turnover, bone loss and increased risk of fractures. We studied the association between 25(OH)D and PTH levels, and their associations with bone mineral density (BMD), bone loss, and prevalence of hip fractures in 615 community-dwelling postmenopausal aged 50 - 97 y...

  18. Anomalous behavior of the level density parameter in neutron and charged particle evaporation

    The compound nucleus 76Kr* was populated at the excitation energy of 75 MeV and angular momentum of 39(ℎ/2π) in fusion reactions with two complementary, mass-symmetric (31P+45Sc) and mass-asymmetric (12C+64Zn) entrance channels. The neutron evaporation spectra were measured and compared with the predictions of statistical model calculations using the transmission coefficients for the spherical nuclei in the inverse absorption channel, the rotating liquid drop model moment of inertia, and the normal systematic value of A/8 for the level density parameter a. The results for the mass-asymmetric reaction are found to be consistent with the predictions of the statistical model calculations. However, for the mass-symmetric reaction (31P+45Sc), the experimental spectra are found to be harder than the theoretical neutron spectra and the statistical model calculations require a lower value of A/10 for the parameter a to reproduce the shape of the experimental spectra, indicating the neutron to be evaporated at higher temperature for the same excitation energy and angular momentum in symmetric system. According to the dynamical model, the formation time (37x10-22 sec) of the compound nucleus for the symmetric 31P+45Sc system is significantly higher than that (29x10-22 sec) for the asymmetric 12C+64Zn system. This may probably lead to the formation of a temperature-equilibrated dinuclear complex that may be responsible for neutron emission at higher temperature in the case of the symmetric system

  19. Impact of Diet Supplemented by Coconut Milk on Corticosterone and Acute Phase Protein Level under High Stocking Density

    Majid SHAKERI; Oskoueian, Ehsan; NAJAFI, Pardis

    2016-01-01

    The purpose of this study was to investigate effects of coconut milk supplementation on corticosterone and acute phase protein level under high stocking density. A total 300 Cobb 500 male chicks were placed in cages and stocked as 10 birds/cage (normal stocking density) and 15 birds/cage (high stocking density). The treatments were as (i) control diet and stocked at 10 and 15 birds/cage (ii) control diet + 3% coconut milk from 1-42 day and stocked at 10 and 15 birds/cage (iii) control diet + ...

  20. High flux transmutation of fission products and actinides

    Long-lived fission products and minor actinides accumulated in spent nuclear fuel of power reactors comprise the major part of high level radwaste. Their incineration is important from the point of view of radwaste management. Transmutation of these nuclides by means of neutron irradiation can be performed either in conventional nuclear reactors, or in specialized transmutation reactors, or in ADS facilities with subcritical reactor and neutron source with application of proton accelerator. Different types of transmutation nuclear facilities can be used in order to insure optimal incineration conditions for radwaste. The choice of facility type for optimal transmutation should be based on the fundamental data in the physics of nuclide transformations. Transmutation of minor actinides leads to the increase of radiotoxicity during irradiation. It takes significant time compared to the lifetime of reactor facility to achieve equilibrium without effective transmutation. High flux nuclear facilities allow to minimize these draw-backs of conventional facilities with both thermal and fast neutron spectrum. They provide fast approach to equilibrium and low level of equilibrium mass and radiotoxicity of transmuted actinides. High flux facilities are advantageous also for transmutation of long-lived fission products as they provide short incineration time

  1. Crystalline matrices for the immobilization of plutonium and actinides

    Anderson, E.B.; Burakov, E.E.; Galkin, Ya.B.; Starchenko, V.A.; Vasiliev, V.G. [V.G. Khlopin Radium Institute, St. Petersburg (Russian Federation)

    1996-05-01

    The management of weapon plutonium, disengaged as a result of conversion, is considered together with the problem of the actinide fraction of long-lived high level radioactive wastes. It is proposed to use polymineral ceramics based on crystalline host-phases: zircon ZrSiO{sub 4} and zirconium dioxide ZrO{sub 2}, for various variants of the management of plutonium and actinides (including the purposes of long-term safe storage or final disposal from the human activity sphere). It is shown that plutonium and actinides are able to form with these phases on ZrSiO{sub 4} and ZrO{sub 2} was done on laboratory level by the hot pressing method, using the plasmochemical calcination technology. To incorporate simulators of plutonium into the structure of ZrSiO{sub 4} and ZrO{sub 2} in the course of synthesis, an original method developed by the authors as a result of studying the high-uranium zircon (Zr,U) SiO{sub 4} form Chernobyl {open_quotes}lavas{close_quotes} was used.

  2. Retrieval of effective leaf area index (LAIe) and leaf area density (LAD) profile at individual tree level using high density multi-return airborne LiDAR

    Lin, Yi; West, Geoff

    2016-08-01

    As an important canopy structure indicator, leaf area index (LAI) proved to be of considerable implications for forest ecosystem and ecological studies, and efficient techniques for accurate LAI acquisitions have long been highlighted. Airborne light detection and ranging (LiDAR), often termed as airborne laser scanning (ALS), once was extensively investigated for this task but showed limited performance due to its low sampling density. Now, ALS systems exhibit more competing capacities such as high density and multi-return sampling, and hence, people began to ask the questions like-"can ALS now work better on the task of LAI prediction?" As a re-examination, this study investigated the feasibility of LAI retrievals at the individual tree level based on high density and multi-return ALS, by directly considering the vertical distributions of laser points lying within each tree crown instead of by proposing feature variables such as quantiles involving laser point distribution modes at the plot level. The examination was operated in the case of four tree species (i.e. Picea abies, Pinus sylvestris, Populus tremula and Quercus robur) in a mixed forest, with their LAI-related reference data collected by using static terrestrial laser scanning (TLS). In light of the differences between ALS- and TLS-based LAI characterizations, the methods of voxelization of 3D scattered laser points, effective LAI (LAIe) that does not distinguish branches from canopies and unified cumulative LAI (ucLAI) that is often used to characterize the vertical profiles of crown leaf area densities (LADs) was used; then, the relationships between the ALS- and TLS-derived LAIes were determined, and so did ucLAIs. Tests indicated that the tree-level LAIes for the four tree species can be estimated based on the used airborne LiDAR (R2 = 0.07, 0.26, 0.43 and 0.21, respectively) and their ucLAIs can also be derived. Overall, this study has validated the usage of the contemporary high density multi

  3. Characterization Of Actinides In Simulated Alkaline Tank Waste Sludges And Leachates

    In this project, both the fundamental chemistry of actinides in alkaline solutions (relevant to those present in Hanford-style waste storage tanks), and their dissolution from sludge simulants (and interactions with supernatants) have been investigated under representative sludge leaching procedures. The leaching protocols were designed to go beyond conventional alkaline sludge leaching limits, including the application of acidic leachants, oxidants and complexing agents. The simulant leaching studies confirm in most cases the basic premise that actinides will remain in the sludge during leaching with 2-3 M NaOH caustic leach solutions. However, they also confirm significant chances for increased mobility of actinides under oxidative leaching conditions. Thermodynamic data generated improves the general level of experiemental information available to predict actinide speciation in leach solutions. Additional information indicates that improved Al removal can be achieved with even dilute acid leaching and that acidic Al(NO3)3 solutions can be decontaminated of co-mobilized actinides using conventional separations methods. Both complexing agents and acidic leaching solutions have significant potential to improve the effectiveness of conventional alkaline leaching protocols. The prime objective of this program was to provide adequate insight into actinide behavior under these conditions to enable prudent decision making as tank waste treatment protocols develop.

  4. CHARACTERIZATION OF ACTINIDES IN SIMULATED ALKALINE TANK WASTE SLUDGES AND LEACHATES

    Nash, Kenneth L.

    2008-11-20

    In this project, both the fundamental chemistry of actinides in alkaline solutions (relevant to those present in Hanford-style waste storage tanks), and their dissolution from sludge simulants (and interactions with supernatants) have been investigated under representative sludge leaching procedures. The leaching protocols were designed to go beyond conventional alkaline sludge leaching limits, including the application of acidic leachants, oxidants and complexing agents. The simulant leaching studies confirm in most cases the basic premise that actinides will remain in the sludge during leaching with 2-3 M NaOH caustic leach solutions. However, they also confirm significant chances for increased mobility of actinides under oxidative leaching conditions. Thermodynamic data generated improves the general level of experiemental information available to predict actinide speciation in leach solutions. Additional information indicates that improved Al removal can be achieved with even dilute acid leaching and that acidic Al(NO3)3 solutions can be decontaminated of co-mobilized actinides using conventional separations methods. Both complexing agents and acidic leaching solutions have significant potential to improve the effectiveness of conventional alkaline leaching protocols. The prime objective of this program was to provide adequate insight into actinide behavior under these conditions to enable prudent decision making as tank waste treatment protocols develop.

  5. Enhancing the actinide sciences in Europe through hot laboratories networking and pooling: from ACTINET to TALISMAN

    Since 2004, Europe supports the strengthening of the European actinides sciences scientific community through the funding of dedicated networks: (i) from 2004 to 2008, the ACTINET6 network of excellence (6. Framework Programme) gathered major laboratories involved in nuclear research and a wide range of academic research organisations and universities with the specific aims of funding and implementing joint research projects to be performed within the network of pooled facilities; (ii) from 2009 to 2013, the ACTINET-I3 integrated infrastructure initiative (I3) supports the cost of access of any academics in the pooled EU hot laboratories. In this continuation, TALISMAN (Trans-national Access to Large Infrastructures for a Safe Management of Actinides) gathers now the main European hot laboratories in actinides sciences in order to promote their opening to academics and universities and strengthen the EU-skills in actinides sciences. Furthermore, a specific focus is set on the development of advanced cutting-edge experimental and spectroscopic capabilities, the combination of state-of-the art experimental with theoretical first-principle methods on a quantum mechanical level and to benefit from the synergy between the different scientific and technical communities. ACTINET-I3 and TALISMAN attach a great importance and promote the Education and Training of the young generation of actinides scientists in the Trans-national access but also by organizing Schools (general Summer Schools or Theoretical User Lab Schools) or by granting students to attend International Conference on actinide sciences. (authors)

  6. Nuclear Level Densities for Modeling Nuclear Reactions: An Efficient Approach Using Statistical Spectroscopy

    The general goal of the project is to develop and implement computer codes and input files to compute nuclear densities of state. Such densities are important input into calculations of statistical neutron capture, and are difficult to access experimentally. In particular, we will focus on calculating densities for nuclides in the mass range A ∼ 50-100. We use statistical spectroscopy, a moments method based upon a microscopic framework, the interacting shell model. Second year goals and milestones: Develop two or three competing interactions (based upon surface-delta, Gogny, and NN-scattering) suitable for application to nuclei up to A = 100. Begin calculations for nuclides with A = 50-70

  7. Shell Effect and Temperature Influence on Nuclear Level Density Parameter: the role of the effective mass interaction

    The level density parameter is a very important ingredient in statistic study of nuclear reaction, it has been studied to low energies excitation E < 2MeV where it values is approximately constant, experimental results to energies of excitation more than 2 MeV has been obtained of evaporation spectrum, to nuclei with A=160. In this work we present a calculation of densities level parameter, for a wide range of mass and temperature, taking in accounts the shell effects and the mass effective interaction. The result has been carried out within the semi classical approximation, for the single particle level densities. We results have a reasonable agreement with the experimental data available. (Author)

  8. Electronic structure and magnetic properties of actinides

    The study of the actinide series shows the change between transition metal behavior and lanthanide behavior, between constant weak paramagnetism for thorium and strong Curie-Weiss paramagnetism for curium. Curium is shown to be the first metal of the actinide series to be magnetically ordered, its Neel temperature being 52K. The magnetic properties of the actinides depending on all the peripheral electrons, their electronic structure was studied and an attempt was made to determine it by means of a phenomenological model. Attempts were also made to interrelate the different physical properties which depend on the outer electronic structure

  9. Actinide chemistry in the far field

    The environmental chemistry of the actinides is complicated due both to the extensive redox and coordination chemistry of the elements and also to the complexity of the reactive phases encountered in natural environments. In the far field, interactions with reactive surfaces, coatings and colloidal particles will play a crucial role in controlling actinide mobility. By virtue of both their abundance and reactivity; clays and other layer aluminosilicate minerals, hydrous oxides and organic matter (humic substances) are all identified as having the potential to react with actinide ions and some possible modes of interaction are described, together with experimental evidence for their occurrence. (author)

  10. Spin and orbital moments in actinide compounds

    Lebech, B.; Wulff, M.; Lander, G.H.

    1991-01-01

    -electron band-structure calculations, is that the orbital moments of the actinide 5f electrons are considerably reduced from the values anticipated by a simple application of Hund's rules. To test these ideas, and thus to obtain a measure of the hybridization, we have performed a series of neutron scattering...... experiments designed to determine the magnetic moments at the actinide and transition-metal sublattice sites in compounds such as UFe2, NpCo2, and PuFe2 and to separate the spin and orbital components at the actinide sites. The results show, indeed, that the ratio of the orbital to spin moment is reduced as...

  11. Chemical properties of the heavier actinides and transactinides

    The chemical properties of each of the elements 99 (Es) through 105 are reviewed and their properties correlated with the electronic structure expected for 5f and 6d elements. A major feature of the heavier actinides, which differentiates them from the comparable lanthanides, is the increasing stability of the divalent oxidation state with increasing atomic number. The divalent oxidation state first becomes observable in the anhydrous halides of californium and increases in stability through the series to nobelium, where this valency becomes predominant in aqueous solution. In comparison with the analogous 4f electrons, the 5f electrons in the latter part of the series are more tightly bound. Thus, there is a lowering of the 5f energy levels with respect to the Fermi level as the atomic number increases. The metallic state of the heavier actinides has not been investigated except from the viewpoint of the relative volatility among members of the series. In aqueous solutions, ions of these elements behave as a normal trivalent actinides and lanthanides (except for nobelium). Their ionic radii decrease with increasing nuclear charge which is moderated because of increased screening of the outer 6p electrons by the 5f electrons. The actinide series of elements is completed with the element lawrencium (Lr) in which the electronic configuration is 5f147s27p. From Mendeleev's periodicity and Dirac-Fock calculations, the next group of elements is expected to be a d-transition series corresponding to the elements Hf through Hg. The chemical properties of elements 104 and 105 only have been studied and they indeed appear to show the properties expected of eka-Hf and eka-Ta. However, their nuclear lifetimes are so short and so few atoms can be produced that a rich variety of chemical information is probably unobtainable

  12. Chemical properties of the heavier actinides and transactinides

    Hulet, E.K.

    1981-01-01

    The chemical properties of each of the elements 99 (Es) through 105 are reviewed and their properties correlated with the electronic structure expected for 5f and 6d elements. A major feature of the heavier actinides, which differentiates them from the comparable lanthanides, is the increasing stability of the divalent oxidation state with increasing atomic number. The divalent oxidation state first becomes observable in the anhydrous halides of californium and increases in stability through the series to nobelium, where this valency becomes predominant in aqueous solution. In comparison with the analogous 4f electrons, the 5f electrons in the latter part of the series are more tightly bound. Thus, there is a lowering of the 5f energy levels with respect to the Fermi level as the atomic number increases. The metallic state of the heavier actinides has not been investigated except from the viewpoint of the relative volatility among members of the series. In aqueous solutions, ions of these elements behave as a normal trivalent actinides and lanthanides (except for nobelium). Their ionic radii decrease with increasing nuclear charge which is moderated because of increased screening of the outer 6p electrons by the 5f electrons. The actinide series of elements is completed with the element lawrencium (Lr) in which the electronic configuration is 5f/sup 14/7s/sup 2/7p. From Mendeleev's periodicity and Dirac-Fock calculations, the next group of elements is expected to be a d-transition series corresponding to the elements Hf through Hg. The chemical properties of elements 104 and 105 only have been studied and they indeed appear to show the properties expected of eka-Hf and eka-Ta. However, their nuclear lifetimes are so short and so few atoms can be produced that a rich variety of chemical information is probably unobtainable.

  13. Endohedral Fullerenes with Actinide-Actinide Bonds: Unwilling Bonding in U2@C80

    Foroutan-Nejad, C.; Patzschke, M.; Straka, Michal

    Opole: -, 2014. [MMNB 2014. Polish-Taiwanese Conference. From Molecular Modeling to Nano- and Biotechnology . 04.09.2014-06.09.2014, Opole] R&D Projects: GA ČR(CZ) GA14-03564S Grant ostatní: European Social Fund(XE) CZ.1.07/2.3.00/30.009 Institutional support: RVO:61388963 Keywords : endohedral actinide fullerene * U-U bonding * actinide-actinide bonding Subject RIV: CF - Physical ; Theoretical Chemistry

  14. Multidimensionally constrained relativistic mean-field study of triple-humped barriers in actinides

    Zhao, Jie; Lu, Bing-Nan; Vretenar, Dario; Zhao, En-Guang; Zhou, Shan-Gui

    2015-01-01

    Background: Potential energy surfaces (PES's) of actinide nuclei are characterized by a two-humped barrier structure. At large deformations beyond the second barrier, the occurrence of a third barrier was predicted by macroscopic-microscopic model calculations in the 1970s, but contradictory results were later reported by a number of studies that used different methods. Purpose: Triple-humped barriers in actinide nuclei are investigated in the framework of covariant density functional theory (CDFT). Methods: Calculations are performed using the multidimensionally constrained relativistic mean field (MDC-RMF) model, with the nonlinear point-coupling functional PC-PK1 and the density-dependent meson exchange functional DD-ME2 in the particle-hole channel. Pairing correlations are treated in the BCS approximation with a separable pairing force of finite range. Results: Two-dimensional PES's of 226,228,230,232Th and 232,235,236,238U are mapped and the third minima on these surfaces are located. Then one-dimensional potential energy curves along the fission path are analyzed in detail and the energies of the second barrier, the third minimum, and the third barrier are determined. The functional DD-ME2 predicts the occurrence of a third barrier in all Th nuclei and 238U . The third minima in 230 ,232Th are very shallow, whereas those in 226 ,228Th and 238U are quite prominent. With the functional PC-PK1 a third barrier is found only in 226 ,228 ,230Th . Single-nucleon levels around the Fermi surface are analyzed in 226Th, and it is found that the formation of the third minimum is mainly due to the Z =90 proton energy gap at β20≈1.5 and β30≈0.7 . Conclusions: The possible occurrence of a third barrier on the PES's of actinide nuclei depends on the effective interaction used in multidimensional CDFT calculations. More pronounced minima are predicted by the DD-ME2 functional, as compared to the functional PC-PK1. The depth of the third well in Th isotopes decreases

  15. PF-4 actinide disposition strategy

    The dwindling amount of Security Category I processing and storage space across the DOE Complex has driven the need for more effective storage of nuclear materials at LANL's Plutonium Facility's (PF-4's) vault. An effort was begun in 2009 to create a strategy, a roadmap, to identify all accountable nuclear material and determine their disposition paths, the PF-4 Actinide Disposition Strategy (PADS). Approximately seventy bins of nuclear materials with similar characteristics - in terms of isotope, chemical form, impurities, disposition location, etc. - were established in a database. The ultimate disposition paths include the material to remain at LANL, disposition to other DOE sites, and disposition to waste. If all the actions described in the document were taken, over half of the containers currently in the PF-4 vault would been eliminated. The actual amount of projected vault space will depend on budget and competing mission requirements, however, clearly a significant portion of the current LANL inventory can be either dispositioned or consolidated.

  16. Surface energy and work function of the light actinides

    Kollár, J.; Vitos, Levente; Skriver, Hans Lomholt

    1994-01-01

    We have calculated the surface energy and work function of the light actinides Fr, Ra, Ac, Th, Pa, U, Np, and Pu by means of a Green's-function technique based on the linear-muffin-tin-orbitals method within the tight-binding representation. In these calculations we apply an energy functional which...... combines the kinetic energy calculated within the atomic-sphere approximation with Coulomb- and exchange-correlation-energy terms calculated by means of the complete nonspherically symmetric charge density derived from the atomic-sphere potential within nonoverlapping and space-filling cells. The...... calculated surface energies and work functions are in good agreement with the limited experimental data....

  17. Regional lunar gravity anomaly recovery with the GRAIL Level-1b data, and pin-point crustal density estimation with the GRAIL Level-2 and LRO topography data

    Hashimoto, M.; Heki, K.

    2014-12-01

    We report the lunar gravity anomaly recovery using the GRAIL Level-1b and Level-2 data, downloaded from the PDS Geoscience Node at the Washington University. First, we used the GNV1b (satellite position data) and KBR1b (inter-satellite ranging data) files of the Level-1b data to estimate the surface mass distribution on the Moon following the method of Sugano and Heki (EPS 2004; GRL 2005). We confirmed that we could recover the gravity anomalies similar to the Level-2 data with spatial resolution of ~0.8 degrees using low altitude portions of the data. Next, we downloaded the GRAIL Level-2 data set (spherical harmonics with degree/order complete to 660) together with the topography data by LRO laser altimetry, and tried to estimate the pin-point surface crustal density. First, we selected a certain square as large as ~60 km, and compared the gravity and topography values at grid points within the square. They are roughly proportional, and the slope provides information on the density of the material making the topography. This method, however, causes apparent positive correlation between density and average topographic height of about 0.2 g/cm^3/km. We (wrongly) assume that the mass anomalies lie on the reference surface. Then, the mass above (below) the reference surface is interpreted heavier/lighter than its real density. We performed a-posteriori correction of the altitude-dependent errors in the estimated density. We finally focus on a few positive gravity anomalies on the nearside (such as those close to the Copernicus crater) that are not associated with any topographic high. We will try to constrain the subsurface structure of the dense material responsible for the anomaly using both Level-1b and -2 data.

  18. Subsurface interactions of actinide species and microorganisms. Implications for the bioremediation of actinide-organic mixtures

    By reviewing how microorganisms interact with actinides in subsurface environments, the way how bioremediation controls the fate of actinides is assessed. Actinides often are co-contaminants with strong organic chelators, chlorinated solvents, and fuel hydrocarbons. Bioremediation can immobilize the actinides, biodegrade the co-contaminants, or both. Actinides at the IV oxidation state are the least soluble, and microorganisms accelerate precipitation by altering the actinide's oxidation state or its speciation. The way how microorganisms directly oxidize or reduce actinides and how microbiological reactions that biodegrade strong organic chelators, alter the pH, and consume or produce precipitating anions strongly affect actinide speciation and, therefore, mobility is described. Why inhibition caused by chemical or radiolytic toxicities uniquely affects microbial reactions is explained. Due to the complex interactions of the microbiological and chemical phenomena, mathematical modeling is an essential tool for research on and application of bioremediation involving co-contamination with actinides. Development of mathematical models that link microbiological and geochemical reactions is described. Throughout, the key research needs are identified. (author)

  19. Subsurface interactions of actinide species and microorganisms : implications for the bioremediation of actinide-organic mixtures.

    Banaszak, J.E.; Reed, D.T.; Rittmann, B.E.

    1999-02-12

    By reviewing how microorganisms interact with actinides in subsurface environments, we assess how bioremediation controls the fate of actinides. Actinides often are co-contaminants with strong organic chelators, chlorinated solvents, and fuel hydrocarbons. Bioremediation can immobilize the actinides, biodegrade the co-contaminants, or both. Actinides at the IV oxidation state are the least soluble, and microorganisms accelerate precipitation by altering the actinide's oxidation state or its speciation. We describe how microorganisms directly oxidize or reduce actinides and how microbiological reactions that biodegrade strong organic chelators, alter the pH, and consume or produce precipitating anions strongly affect actinide speciation and, therefore, mobility. We explain why inhibition caused by chemical or radiolytic toxicities uniquely affects microbial reactions. Due to the complex interactions of the microbiological and chemical phenomena, mathematical modeling is an essential tool for research on and application of bioremediation involving co-contamination with actinides. We describe the development of mathematical models that link microbiological and geochemical reactions. Throughout, we identify the key research needs.

  20. Subsurface interactions of actinide species and microorganisms : implications for the bioremediation of actinide-organic mixtures

    By reviewing how microorganisms interact with actinides in subsurface environments, we assess how bioremediation controls the fate of actinides. Actinides often are co-contaminants with strong organic chelators, chlorinated solvents, and fuel hydrocarbons. Bioremediation can immobilize the actinides, biodegrade the co-contaminants, or both. Actinides at the IV oxidation state are the least soluble, and microorganisms accelerate precipitation by altering the actinide's oxidation state or its speciation. We describe how microorganisms directly oxidize or reduce actinides and how microbiological reactions that biodegrade strong organic chelators, alter the pH, and consume or produce precipitating anions strongly affect actinide speciation and, therefore, mobility. We explain why inhibition caused by chemical or radiolytic toxicities uniquely affects microbial reactions. Due to the complex interactions of the microbiological and chemical phenomena, mathematical modeling is an essential tool for research on and application of bioremediation involving co-contamination with actinides. We describe the development of mathematical models that link microbiological and geochemical reactions. Throughout, we identify the key research needs

  1. A first principles investigation of the electronic structure of actinide oxides

    Petit, Leon; Svane, Axel; Szotek, Zdzislawa;

    2010-01-01

    The ground state electronic structures of the actinide oxides AO, A2O3 and AO2 (A=U, Np, Pu, Am, Cm, Bk, Cf) are determined from first-principles calculations using the selfinteraction corrected local spin-density approximation. Our study reveals a strong link between preferred oxidation number a...

  2. Actinide research to solve some practical problems

    The following topics are discussed: generation of plutonium inventories by nuclear power plants; resettlement of the Marshallese Islanders into an actinide contaminated environment; high radiation background areas of the world; and radiation hazards to uranium miners

  3. Overview of actinide chemistry in the WIPP

    Borkowski, Marian [Los Alamos National Laboratory; Lucchini, Jean - Francois [Los Alamos National Laboratory; Richmann, Michael K [Los Alamos National Laboratory; Reed, Donald T [Los Alamos National Laboratory; Khaing, Hnin [Los Alamos National Laboratory; Swanson, Juliet [Los Alamos National Laboratory

    2009-01-01

    The year 2009 celebrates 10 years of safe operations at the Waste Isolation Pilot Plant (WIPP), the only nuclear waste repository designated to dispose defense-related transuranic (TRU) waste in the United States. Many elements contributed to the success of this one-of-the-kind facility. One of the most important of these is the chemistry of the actinides under WIPP repository conditions. A reliable understanding of the potential release of actinides from the site to the accessible environment is important to the WIPP performance assessment (PA). The environmental chemistry of the major actinides disposed at the WIPP continues to be investigated as part of the ongoing recertification efforts of the WIPP project. This presentation provides an overview of the actinide chemistry for the WIPP repository conditions. The WIPP is a salt-based repository; therefore, the inflow of brine into the repository is minimized, due to the natural tendency of excavated salt to re-seal. Reducing anoxic conditions are expected in WIPP because of microbial activity and metal corrosion processes that consume the oxygen initially present. Should brine be introduced through an intrusion scenario, these same processes will re-establish reducing conditions. In the case of an intrusion scenario involving brine, the solubilization of actinides in brine is considered as a potential source of release to the accessible environment. The following key factors establish the concentrations of dissolved actinides under subsurface conditions: (1) Redox chemistry - The solubility of reduced actinides (III and IV oxidation states) is known to be significantly lower than the oxidized forms (V and/or VI oxidation states). In this context, the reducing conditions in the WIPP and the strong coupling of the chemistry for reduced metals and microbiological processes with actinides are important. (2) Complexation - For the anoxic, reducing and mildly basic brine systems in the WIPP, the most important

  4. Electronic structure and correlation effects in actinides

    Albers, R.C.

    1998-12-01

    This report consists of the vugraphs given at a conference on electronic structure. Topics discussed are electronic structure, f-bonding, crystal structure, and crystal structure stability of the actinides and how they are inter-related.

  5. Advanced Aqueous Separation Systems for Actinide Partitioning

    Nash, Kenneth L.; Clark, Sue; Meier, G Patrick; Alexandratos, Spiro; Paine, Robert; Hancock, Robert; Ensor, Dale

    2012-03-21

    One of the most challenging aspects of advanced processing of spent nuclear fuel is the need to isolate transuranium elements from fission product lanthanides. This project expanded the scope of earlier investigations of americium (Am) partitioning from the lanthanides with the synthesis of new separations materials and a centralized focus on radiochemical characterization of the separation systems that could be developed based on these new materials. The primary objective of this program was to explore alternative materials for actinide separations and to link the design of new reagents for actinide separations to characterizations based on actinide chemistry. In the predominant trivalent oxidation state, the chemistry of lanthanides overlaps substantially with that of the trivalent actinides and their mutual separation is quite challenging.

  6. BWR Assembly Optimization for Minor Actinide Recycling

    G. Ivan Maldonado; John M. Christenson; J.P. Renier; T.F. Marcille; J. Casal

    2010-03-22

    The Primary objective of the proposed project is to apply and extend the latest advancements in LWR fuel management optimization to the design of advanced boiling water reactor (BWR) fuel assemblies specifically for the recycling of minor actinides (MAs).

  7. Development of PM2.5 density distribution visualization system using ground-level sensor network and Mie lidar

    Okumura, Hiroshi; Akaho, Taiga; Kojiro, Yu; Uchino, Osamu; Morino, Isamu; Yokota, Tatsuya; Nagai, Tomohiro; Sakai, Tetsu; Maki, Takashi; Yamazaki, Akihiro; Arai, Kohei

    2014-10-01

    Atmospheric particulate matters (PM) are tiny pieces of solid or liquid matter associated with the Earth's atmosphere. They are suspended in the atmosphere as atmospheric aerosol. Recently, density of fine particles PM2.5, diameter of 2.5 micrometers or less, from China is serious environmental issue in East part of Asia. In this study, the authors have developed a PM2.5 density distribution visualization system using ground-level sensor network dataset and Mie lidar dataset. The former dataset is used for visualization of horizontal PM2.5 density distribution and movement analysis, the latter dataset is used for visualization of vertical PM2.5 density distribution and movement analysis.

  8. Molecular Biology at the Quantum Level: Can Modern Density Functional Theory Forge the Path?

    Kolb, Brian; 10.1142/S1793984412300063

    2012-01-01

    Recent years have seen vast improvements in the ability of rigorous quantum-mechanical methods to treat systems of interest to molecular biology. In this review article, we survey common computational methods used to study such large, weakly bound systems, starting from classical simulations and reaching to quantum chemistry and density functional theory. We sketch their underlying frameworks and investigate their strengths and weaknesses when applied to potentially large biomolecules. In particular, density functional theory---a framework that can treat thousands of atoms on firm theoretical ground---can now accurately describe systems dominated by weak van der Waals interactions. This newfound ability has rekindled interest in using this tried-and-true approach to investigate biological systems of real importance. In this review, we focus on some new methods within density functional theory that allow for accurate inclusion of the weak interactions that dominate binding in biological macromolecules. Recent ...

  9. On the strength of coriolis coupling in actinide nuclei

    Coriolis Coupling Vsub(cor) plays an important role in deformed nuclei. Vsub(cor) is proportional to h/2π2/J[j(j + 1) -Ω(Ω + 1)]sup(1/2) and therefore is particularly significant in the nuclei with large j and low Ω Nilsson levels close to Fermi surface: n(isub(13/2)) in A = 150 - 170 rare-earth nuclei and p(isub(13/2)) and n(jsub(15/2)) in A>224 actinide nuclei. Because of larger j (n(jsub(15/2)) versus n(isub(13/2)) ) and smaller deformations (β asymptotically equals 0.22 versus β asymptotically equals 0.28) it was reasonable to expect that in actinide nuclei ''Coriolis'' effects are stronger than in the rare earth nuclei. Recently it was realized that the strength of observed ''Coriolis'' effects depends not only on the genuine Coriolis Coupling but also on the interplay between Coriolis and pairing forces which leads to an interference between the wave functions of two mixing rotational bands. As a consequence the effective interaction Vsub(eff) of both bands is an oscillating function of the degree of shell filling (or chemical potential lambda sub(F)). It was shown that in the rare earth nuclei this interference strongly influenced conclusions about the trends in the Coriolis coupling strength and explained many of the observed band-mixing features (the sharpness of back-banding curves, details of the blocking effect etc.). From theoretical analysis it was concluded that in the majority of actinide nuclei the effective interaction Vsub(eff), is strong and therefore the Coriolis band-mixing have to be very strong. In this paper we would like to demonstrate that contrary to these predictions experimental data suggest that Coriolis band-mixing in studied actinide nuclei is relatively weak and possibly significantly weaker than in rare earth nuclei. (J.P.N.)

  10. Lanthanides and actinides in ionic liquids

    Binnemans, Koen

    2007-01-01

    This lecture gives an overview of the research possibilities offered by combining f-elements (lanthanides and actinides) with ionic liquids [1] Many ionic liquids are solvents with weakly coordinating anions. Solvation of lanthanide and actinide ions in these solvents is different from what is observed in conventional organic solvents and water. The poorly solvating behavior can also lead to the formation of coordination compounds with low coordination numbers. The solvation of f-elements can...

  11. New molecules to separate actinides: the picolinamides

    The reprocessing of spent fuel is made with the Purex process, funded on liquid-liquid extraction of uranium nitrates(VI) and plutonium nitrates(IV) by the BTP (tributyl phosphate). To improve this proceeding, we look for extractants which allow, beyond U and Pu extractions, these of actinides (II) and allow separation of the whole actinides from the fission products, which have an important fraction of lanthanides. A new family seems to give good results: the picolinamides

  12. Lattice effects in the light actinides

    The light actinides show a variety of lattice effects that do not normally appear in other regions of the periodic table. The article will cover the crystal structures of the light actinides, their atomic volumes, their thermal expansion behavior, and their elastic behavior as reflected in recent thermal vibration measurements made by neutron diffraction. A discussion of the melting points will be given in terms of the thermal vibration measurements. Pressure effects will be only briefly indicated

  13. Final Report Full-Scale Test of DWPF Advanced Liquid-Level and Density Measurement Bubblers

    too labor intensive for practical use.All of the large diameter bubbler tubes tested could be readily cleaned in place by either blowing them down with justhigh pressure air or water (approx. 90 psig). While the use of both air and water produced the cleanest bubbler, using justair removed most of the slurry build-up, and the use of water resulted in basically a slurry free surface. For the smalldiameter bubbler tubes it was necessary to use high pressure air and water (approx. 90 psig) to effectively clean them. The water was only sent through the porous jacket and not introduced down the air line. However, even under these conditions there was one case where a plug was not removed when both air and water were used.Primary recommendation: The large diameter probe is the best choice since none of the three tested plugged during the2-mouth test period to the point which compromised liquid-level measure. However, after a week's operation at boilingtemperatures several inches of a soft sludge builds up within the tubes. This sludge can be easily removed in place witheither high pressure air or water (approx. 90 psig). A full-scale verifi-cation test should be carried out in S-area to confirm the conclusion.Secondary recommendation: The small-diameter porous tube bubbler is recommended when an access port cannot accommodate thelarger diameter probe. Bubbler number-sign 1 operated accurately during most of the test period. This probe had the highest water flowrate (approx. 1.6 gallons/day) and had the least distance from the slurry upper surface (37 inches). This probe can be made to accurately operate at lower depths if the 8-inch-long porous tube is made longer and the water flow rate made higher.Substituting the current level and density probes (Holledge) with bubbler probes will result in a significant cost savings (inexpensive materials, less labor to manufacture, less labor to maintain, less down time due to less frequent instrument replacement)

  14. Final Report Full-Scale Test of DWPF Advanced Liquid-Level and Density Measurement Bubblers

    Duignan, M.R. [Westinghouse Savannah River Company, AIKEN, SC (United States); Weeks, G.E.

    1999-07-01

    may be too labor intensive for practical use.All of the large diameter bubbler tubes tested could be readily cleaned in place by either blowing them down with justhigh pressure air or water (approx. 90 psig). While the use of both air and water produced the cleanest bubbler, using justair removed most of the slurry build-up, and the use of water resulted in basically a slurry free surface. For the smalldiameter bubbler tubes it was necessary to use high pressure air and water (approx. 90 psig) to effectively clean them. The water was only sent through the porous jacket and not introduced down the air line. However, even under these conditions there was one case where a plug was not removed when both air and water were used.Primary recommendation: The large diameter probe is the best choice since none of the three tested plugged during the2-mouth test period to the point which compromised liquid-level measure. However, after a week`s operation at boilingtemperatures several inches of a soft sludge builds up within the tubes. This sludge can be easily removed in place witheither high pressure air or water (approx. 90 psig). A full-scale verifi-cation test should be carried out in S-area to confirm the conclusion.Secondary recommendation: The small-diameter porous tube bubbler is recommended when an access port cannot accommodate thelarger diameter probe. Bubbler {number_sign}1 operated accurately during most of the test period. This probe had the highest water flowrate (approx. 1.6 gallons/day) and had the least distance from the slurry upper surface (37 inches). This probe can be made to accurately operate at lower depths if the 8-inch-long porous tube is made longer and the water flow rate made higher.Substituting the current level and density probes (Holledge) with bubbler probes will result in a significant cost savings (inexpensive materials, less labor to manufacture, less labor to maintain, less down time due to less frequent instrument replacement).

  15. A predictor of atheroma progression in patients achieving very low levels of low-density lipoprotein cholesterol

    Nozue, Tsuyoshi; Yamamoto, Shingo; Tohyama, Shinichi; Fukui, Kazuki; Umezawa, Shigeo; Onishi, Yuko; Kunishima, Tomoyuki; Hibi, Kiyoshi; Terashima, Mitsuyasu; Michishita, Ichiro

    2013-01-01

    An aggressive reduction in low-density lipoprotein cholesterol (LDL-C) with statins produces regression or stabilization of coronary artery plaques. However, after achieving very low levels of LDL-C, atheroma regression is not observed in all patients. The purpose of the present study was to evaluate the determinants of atheroma progression despite achieving very low levels of LDL-C. The effects of 8-month statin therapy on coronary atherosclerosis were evaluated using virtual histology intra...

  16. Reduced plasma adiponectin levels relative to oxidized low density lipoprotein and nitric oxide in coronary artery disease patients

    Gholam Basati; Morteza Pourfarzam; Ahmad Movahedian; Saed Ziaaldin Samsamshariat; Nizal Sarrafzadegan

    2011-01-01

    INTRODUCTION: Adiponectin is a circulating hormone that is produced exclusively by adipocytes and has antiinflammatory and anti-atherogenic properties. The hypothesis that there are differences in adiponectin levels between stable and unstable coronary-artery disease patients remains controversial. Furthermore, the potential relationships between the plasma adiponectin level and the inflammatory and non-inflammatory markers (oxidized low density lipoprotein and nitric oxide) in patients with ...

  17. The Effects of Text Density Levels and the Cognitive Style of Field Dependence on Learning from a CBI Tutorial

    Ipek, Ismail

    2011-01-01

    The purpose of this study was to investigate the effects of variations in text density levels and the cognitive style of field dependence on learning from a CBI tutorial, based on the dependent measures of achievement, reading comprehension, and reading rate, and of lesson completion time. Eighty college undergraduate students were randomly…

  18. Serum apolipoprotein(a) levels and its effect on the measured values of low density lipoprotein cholesterol.

    1995-01-01

    Serum low density lipoprotein cholesterl (LDL-C) and lipoprotein(a)[Lp(a)]levels were analyzed in 1032 sequential cases on routine physical check up, with special attention to the effect of Lp(a) on the LDL-C values. Since the determination of LDL-C by various

  19. Recent progress in actinide borate chemistry.

    Wang, Shuao; Alekseev, Evgeny V; Depmeier, Wulf; Albrecht-Schmitt, Thomas E

    2011-10-21

    The use of molten boric acid as a reactive flux for synthesizing actinide borates has been developed in the past two years providing access to a remarkable array of exotic materials with both unusual structures and unprecedented properties. [ThB(5)O(6)(OH)(6)][BO(OH)(2)]·2.5H(2)O possesses a cationic supertetrahedral structure and displays remarkable anion exchange properties with high selectivity for TcO(4)(-). Uranyl borates form noncentrosymmetric structures with extraordinarily rich topological relationships. Neptunium borates are often mixed-valent and yield rare examples of compounds with one metal in three different oxidation states. Plutonium borates display new coordination chemistry for trivalent actinides. Finally, americium borates show a dramatic departure from plutonium borates, and there are scant examples of families of actinides compounds that extend past plutonium to examine the bonding of later actinides. There are several grand challenges that this work addresses. The foremost of these challenges is the development of structure-property relationships in transuranium materials. A deep understanding of the materials chemistry of actinides will likely lead to the development of advanced waste forms for radionuclides present in nuclear waste that prevent their transport in the environment. This work may have also uncovered the solubility-limiting phases of actinides in some repositories, and allows for measurements on the stability of these materials. PMID:21915396

  20. Performance of a local electron density trigger to select extensive air showers at sea level

    Abbas, T.; Madani, J.; Ashton, F.

    1985-01-01

    Time coincident voltage pulses in the two closely space (1.6m) plastic scintillators were recorded. Most of the recorded events are expeted to be due to electrons in cosmic ray showers whose core fall at some distance from the detectors. This result is confirmed from a measurement of the frequency distribution of the recorded density ratios of the two scintillators.

  1. Glycated albumin and direct low density lipoprotein cholesterol levels in type 2 diabetes mellitus

    Diabetes mellitus is a major risk factor for coronary heart disease (CHD), renal failure, retinopathy, and neuropathy. Lowering glycosylated hemoglobin (HbA1c) as well as low-density lipoprotein-cholesterol (LDL-C) has been associated with a decreased risk of these complications. We evaluated the ut...

  2. Solvent extraction and liquid membrane transport studies of actinides using novel extractants

    For the safe management of radioactive wastes, 'Partitioning and Transmutation' (P and T) is being proposed as a strategy for the mitigation of long term hazards due to minor actinides (MA) and long lived fission products. This requires selective recovery of minor actinides from acidic feeds and thus necessitates development of extractants for their preferential extraction from high level waste. Several 'green' extractants such as functionalized malonamides and diglycolamides (DGA) have shown highly encouraging results. Out of the malonamides, DMDBTDMA and DMDOHEMA have been extensively tested for their actinide partitioning behaviour. Several diglycolamide extractants such as TPDGA, THDGA, TODGA, T2EHDGA and TDDGA have also been evaluated for their extraction properties. Interesting extraction properties of TODGA has led to thorough investigation of this reagent for the development of 'actinide partitioning' flow sheets at various laboratories. Liquid membrane separation of actinides from synthetic high level waste (SHLW) solution has also been carried out and shown highly promising results at significantly lower VOC inventories. About 20 L SHLW has been processed using hollow fiber supported liquid membrane technique. Novel DGA functionalized tripodal and calix(4)arene ligands were also evaluated for the extraction of actinides and fission products. The extraction mechanism was found to be entirely different with the calix(4)arene based DGA ligands as compared to those observed with extractants such as TODGA. Room temperature ionic liquids containing diglycolamide extractants have shown exceptionally high distribution coefficients and the results indicate possibility of selective recovery of Am from acidic waste solutions. Task specific ionic liquids containing DGA functional group have also been evaluated for actinide extraction under varying experimental conditions. (author)

  3. Importance of nuclear triaxiality for electromagnetic strength, level density and neutron capture cross sections in heavy nuclei

    Grosse, Eckart; Massarczyk, Ralph

    2014-01-01

    Cross sections for neutron capture in the range of unresolved resonances are predicted simultaneously to level distances at the neutron threshold for more than 100 spin-0 target nuclei with A >70. Assuming triaxiality in nearly all these nuclei a combined parameterization for both, level density and photon strength is presented. The strength functions used are based on a global fit to IVGDR shapes by the sum of three Lorentzians adding up to the TRK sum rule and theory-based predictions for the A-dependence of pole energies and spreading widths. For the small spins reached by capture level densities are well described by only one free global parameter; a significant collective enhancement due to the deviation from axial symmetry is observed. Reliable predictions for compound nuclear reactions also outside the valley of stability as expected from the derived global parameterization are important for nuclear astrophysics and for the transmutation of nuclear waste.

  4. Static Frame Model Validation with Small Samples Solution Using Improved Kernel Density Estimation and Confidence Level Method

    ZHANG Baoqiang; CHEN Guoping; GUO Qintao

    2012-01-01

    An improved method using kernel density estimation (KDE) and confidence level is presented for model validation with small samples.Decision making is a challenging problem because of input uncertainty and only small samples can be used due to the high costs of experimental measurements.However,model validation provides more confidence for decision makers when improving prediction accuracy at the same time.The confidence level method is introduced and the optimum sample variance is determined using a new method in kernel density estimation to increase the credibility of model validation.As a numerical example,the static frame model validation challenge problem presented by Sandia National Laboratories has been chosen.The optimum bandwidth is selected in kernel density estimation in order to build the probability model based on the calibration data.The model assessment is achieved using validation and accreditation experimental data respectively based on the probability model.Finally,the target structure prediction is performed using validated model,which are consistent with the results obtained by other researchers.The results demonstrate that the method using the improved confidence level and kernel density estimation is an effective approach to solve the model validation problem with small samples.

  5. Level density parameters for the back-shifted Fermi gas model in the mass range 24 ≤ A ≤ 250

    The parameters a and δeff for the back-shifted Fermi gas model are determined for 1224 nuclei. For 272 nuclei the parameters are determined from experimental data on cumulative numbers of low-lying levels and the average spacings between neutron resonances. For the rest of the nuclei the δeff parameter was determined from cumulative numbers of low-lying levels and values of the a parameter obtained by interpolation using the data for the 272 nuclei. A formula is suggested to account for damping of the shell effect at high excitation energies. A comparison is made with previous results and different experimental data on level densities. (author)

  6. Effects of Changing Density and Food Level on Metamorphosis of a Desert Amphibian, Scaphiopus Couchii

    Newman, R.A.

    1994-01-01

    Amphibians that breed in temporary ponds provide a good opportunity to study the ecological and evolutionary consequences of environmental variability. Ephemeral aquatic habitats provide larval amphibians a transient and highly variable opportunity for growth. In the desert ponds used by Couch's spadefoot toad (Scaphiopus couchii), tadpole density varies considerably among ponds and often increases within a pond as it dries. Models of optimal size and timing of metamorphosis predict that, rel...

  7. Microbial transformations of actinides in the environment

    The diversity of microorganisms is still far from understood, although many examples of the microbial biotransformation of stable, pollutant and radioactive elements, involving Bacteria, Archaea and Fungi, are known. In estuarine sediments from the Irish Sea basin, which have been labelled by low level effluent discharges, there is evidence of an annual cycle in Pu solubility, and microcosm experiments have demonstrated both shifts in the bacterial community and changes in Pu solubility as a result of changes in redox conditions. In the laboratory, redox transformation of both U and Pu by Geobacter sulfurreducens has been demonstrated and EXAFS spectroscopy has been used to understand the inability of G. sufurreducens to reduce Np(V). Fungi promote corrosion of metallic U alloy through production of a range of carboxylic acid metabolites, and are capable of translocating the dissolved U before precipitating it externally to the hyphae, as U(VI) phosphate phases. These examples illustrate the far-reaching but complex effects which microorganisms can have on actinide behaviour.

  8. Radioecology of the actinide elements

    Research progress is reported in sections entitled: scope of studies supported by the Department of Energy; oxidation state diagrams are a potential tool for studying the redox chemistry of Pu in natural waters; studies are initiated to investigate the effect of pH and organic matter on the distribution coefficients of Cm with natural sediments; the relative distributions of resuspended and direct deposited Pu in a corn canopy are quantified; the retention of Pu surface contamination by corn plants is being studied; Pu concentrations in tobacco are being determined; concentrations of Pu per unit mass and per unit surface area are compared for subterranean crops; models of Pu behavior in agricultural crops are being validated; distribution of aerially released Pu in loblolly pine plantations is independent of deposition rate; investigation of the effects of chelate and redox potential of the uptake of Pu and Cm by rice is underway; studies of Cm cycling in a floodplain forest have been initiated; the effects of unusually large Pu deposition onto a wheat ecosystem are being studied using computer simulations; long-term kinetic models of Pu behavior in plant-soil systems are being developed; scope of studies supported by the Nuclear Regulatory Commission; growth form of broadleaf crop may affect Pu contents; root uptake of Pu and Cm measured for rice root uptake of Pu and Cm measured for rice; long-term actinide uptake study is continuing at SREL; and uranium cycling in major southeastern agricultural crops being studied

  9. Actinide transmutation in nuclear reactors

    An optimization method is developed to maximize the burning capability of the ALMR while complying with all constraints imposed on the design for reliability and safety. This method leads to a maximal transuranics enrichment, which is being limited by constraints on reactivity. The enrichment can be raised by using the neutrons less efficiently by increasing leakage from the fuel. With the developed optimization method, a metallic and an oxide fueled ALMR were optimized. Both reactors perform equally well considering the burning of transuranics. However, metallic fuel has a much higher heat conductivity coefficient, which in general leads to better safety characteristics. In search of a more effective waste transmuter, a modified Molten Salt Reactor was designed. A MSR operates on a liquid fuel salt which makes continuous refueling possible, eliminating the issue of the burnup reactivity loss. Also, a prompt negative reactivity feedback is possible for an overmoderated reactor design, even when the Doppler coefficient is positive, due to the fuel expansion with fuel temperature increase. Furthermore, the molten salt fuel can be reprocessed based on a reduction process which is not sensitive to the short-lived spontaneously fissioning actinides. (orig./HP)

  10. Interconnection between precipitation density, soil contamination levels and 90Sr and 137Cs content in food stuffs

    Presented are the data dynamically characterizing the density of radioactive fallout, contamination of soil and the main kinds of food stuffs with 137Cs and 90Sr. It is shown that 90Sr contamination of bakery products in the country within the whole period of observation is in direct dependence on the density of atmospheric fallouts as a whole in the northern hemisphere. In the reverse, 90Sr potato contamination primarily correlates with nuclide content in the soil. The dependence between milk contamination and fallout density has an intermediate character as compared with the above types of food stuffs. The same is true for 137Cs, but a clear tendency to a faster decrease in the level of food stuffs contamination is observed. The importance of the soil way in food stuffs contamination and peculiarities of nuclide migration in food stuffs from various types of soil are considered

  11. A Possible Mechanism Linking Hyperglycemia and Reduced High-density Lipoprotein Cholesterol Levels in Diabetes

    高峰; 严同; 赵艳; 尹凡; 胡翠宁

    2010-01-01

    This study investigated the role of glucose in the biogenesis of high-density lipoprotein cholesterol(HDL-C).Mouse primary peritoneal macrophages were harvested and maintained in Dulbecco's modified Eagle's medium(DMEM) containing glucose of various concentrations.The cells were divided into 3 groups in terms of different glucose concentrations in the cultures:Control group(5.6 mmol/L glucose),high glucose concentration groups(16.7 mmol/L and 30 mmol/L glucose).ATP-binding cassette transporter A1(ABCA1) mRN...

  12. Effect of underground working on vitamin D levels and bone mineral densities in coal miners: a controlled study

    Sarikaya, S.; Ozdolap, S.; Mungan, A.G.; Gumustas, S.; Koc, U.; Guven, B.; Begendik, F. [Zonguldak Karaelmas University, Zonguldak (Turkey)

    2006-07-15

    The aim of this study was to determine the effect of underground working on 25-hydroxyvitamin D (25-OHD) levels and bone mineral density (BMD) values in coal miners. Fifty coal miners working underground and 50 surface workers as controls, matched for age and body mass index, from Zonguldak, Turkey, were recruited to the study. Levels of 25-OHD, biochemical bone markers, and lumbar spine and femur BMD values were measured in all study participants. Lumbar spine and femur BMD values were significantly higher in underground workers compared with surface workers, but there was no significant difference in 25-OHD levels between the two groups. Duration of underground working, age, 25-OHD levels, cigarette consumption and dietary calcium intake were not correlated with BMD values. Underground physical working does not seem to be a significant risk factor for low 25-OHD levels or low BMD values.

  13. Local charge neutrality condition, Fermi level and majority carrier density of a semiconductor with multiple localized multi-level intrinsic/impurity defects

    Ken K. Chin

    2011-01-01

    For semiconductors with localized intrinsic/impurity defects,intentionally doped or unintentionally incorporated,that have multiple transition energy levels among charge states,the general formulation of the local charge neutrality condition is given for the determination of the Fermi level and the majority carrier density.A graphical method is used to illustrate the solution of the problem.Relations among the transition energy levels of the multi-level defect are derived using the graphical method.Numerical examples are given for p-doping of the CdTe thin film used in solar panels and semi-insulating Si to illustrate the relevance and importance of the issues discussed in this work.

  14. s-process stellar enhancement factors obtained within the statistical model with parity-dependent level densities

    In stellar environments the medium modifications of the neutron capture cross-sections required for s-process nucleosynthesis simulations are accounted for by the stellar enhancement factors. We have calculated these enhancement factors using the statistical model for compound reactions. Improving previous calculations we take the parity distribution of states at all stages of the reaction into account by using parity-dependent level densities. The effect of this improvement on the stellar enhancement factors is small, although not negligible if one attempts to describe the stellar capture rates with an accuracy of order 10%. We observe, however, that the uncertainties introduced by the insufficient knowledge of the total level densities are noticeably larger. (orig.)

  15. Solubility of actinide surrogates in nuclear glasses

    This paper discusses the results of a study of actinide surrogates in a nuclear borosilicate glass to understand the effect of processing conditions (temperature and oxidizing versus reducing conditions) on the solubility limits of these elements. The incorporation of cerium oxide, hafnium oxide, and neodymium oxide in this borosilicate glass was investigated. Cerium is a possible surrogate for tetravalent and trivalent actinides, hafnium for tetravalent actinides, and neodymium for trivalent actinides. The material homogeneity was studied by optical, scanning electron microscopy. Cerium LIII XANES spectroscopy showed that the Ce3+/Cetotal ratio increased from about 0.5 to 0.9 as the processing temperature increased from 1100 to 1400 deg. C. Cerium LIII XANES spectroscopy also confirmed that the increased Ce solubility in glasses melted under reducing conditions was due to complete reduction of all the cerium in the glass. The most significant results pointed out in the current study are that the solubility limits of the actinide surrogates increases with the processing temperature and that Ce3+ is shown to be more soluble than Ce4+ in this borosilicate glass

  16. TUCS/phosphate mineralization of actinides

    Nash, K.L. [Argonne National Lab., IL (United States)

    1997-10-01

    This program has as its objective the development of a new technology that combines cation exchange and mineralization to reduce the concentration of heavy metals (in particular actinides) in groundwaters. The treatment regimen must be compatible with the groundwater and soil, potentially using groundwater/soil components to aid in the immobilization process. The delivery system (probably a water-soluble chelating agent) should first concentrate the radionuclides then release the precipitating anion, which forms thermodynamically stable mineral phases, either with the target metal ions alone or in combination with matrix cations. This approach should generate thermodynamically stable mineral phases resistant to weathering. The chelating agent should decompose spontaneously with time, release the mineralizing agent, and leave a residue that does not interfere with mineral formation. For the actinides, the ideal compound probably will release phosphate, as actinide phosphate mineral phases are among the least soluble species for these metals. The most promising means of delivering the precipitant would be to use a water-soluble, hydrolytically unstable complexant that functions in the initial stages as a cation exchanger to concentrate the metal ions. As it decomposes, the chelating agent releases phosphate to foster formation of crystalline mineral phases. Because it involves only the application of inexpensive reagents, the method of phosphate mineralization promises to be an economical alternative for in situ immobilization of radionuclides (actinides in particular). The method relies on the inherent (thermodynamic) stability of actinide mineral phases.

  17. Final Report on Actinide Glass Scintillators for Fast Neutron Detection

    Bliss, Mary; Stave, Jean A.

    2012-10-01

    This is the final report of an experimental investigation of actinide glass scintillators for fast-neutron detection. It covers work performed during FY2012. This supplements a previous report, PNNL-20854 “Initial Characterization of Thorium-loaded Glasses for Fast Neutron Detection” (October 2011). The work in FY2012 was done with funding remaining from FY2011. As noted in PNNL-20854, the glasses tested prior to July 2011 were erroneously identified as scintillators. The decision was then made to start from “scratch” with a literature survey and some test melts with a non-radioactive glass composition that could later be fabricated with select actinides, most likely thorium. The normal stand-in for thorium in radioactive waste glasses is cerium in the same oxidation state. Since cerium in the 3+ state is used as the light emitter in many scintillating glasses, the next most common substitute was used: hafnium. Three hafnium glasses were melted. Two melts were colored amber and a third was clear. It barely scintillated when exposed to alpha particles. The uses and applications for a scintillating fast neutron detector are important enough that the search for such a material should not be totally abandoned. This current effort focused on actinides that have very high neutron capture energy releases but low neutron capture cross sections. This results in very long counting times and poor signal to noise when working with sealed sources. These materials are best for high flux applications and access to neutron generators or reactors would enable better test scenarios. The total energy of the neutron capture reaction is not the only factor to focus on in isotope selection. Many neutron capture reactions result in energetic gamma rays that require large volumes or high densities to detect. If the scintillator is to separate neutrons from gamma rays, the capture reactions should produce heavy particles and few gamma rays. This would improve the detection of a

  18. New reagents for actinide-lanthanide group separations

    Organic extractants which possess nitrogen or sulfur donor atoms preferentially complex the trivalent actinide. They are potential reagents for actinide lanthanide group separations, which can be performed at low pH without the addition of inorganic salts

  19. Advanced Silicon Carbide from Molecular Engineering and Actinide Fuels

    In the frame of nuclear fuels studies for generation IV, carbides or oxycarbides assemblies are one of the engaged material for high temperature reactors. The design of the fuels is not yet defined but some structures are actually considered with SiC as matrix for the actinide fuel. In this work we have studied the synthesis of a multi-scale structure controlled SiC matrix using molecular silicon organometallic precursors. The aim of this work was to develop a way to obtain multi-scale SiC matrix material which could be engineered to fit in any fuel structure defined for generation IV fuels. The control of this multi-scale structure was done using several simulation methods specific of the low temperature solution synthesis of the precursor. In a first step, we have focused our effort on the synthesis of the SiC material. A first level of template was successfully done by the use of solid silica 500 nm balls. A second level of template was studied by the use of meso-porous silica, structured at a 50 nm level. At least, supra-molecular simulation in non aqueous media was considered with the difficulty to build a molecular assembly (inverse micelles). In a second step, we have functionalized the primary silane phase with actinide complexing agent in order to blend directly the actinide inside this primary phase in a controlled way. During these studies, a new one pot synthesis route to obtain the functionalized primary silane phase was developed. (authors)

  20. Correlation test to assess low-level processing of high-density oligonucleotide microarray data

    Bergh Jonas

    2005-03-01

    Full Text Available Abstract Background There are currently a number of competing techniques for low-level processing of oligonucleotide array data. The choice of technique has a profound effect on subsequent statistical analyses, but there is no method to assess whether a particular technique is appropriate for a specific data set, without reference to external data. Results We analyzed coregulation between genes in order to detect insufficient normalization between arrays, where coregulation is measured in terms of statistical correlation. In a large collection of genes, a random pair of genes should have on average zero correlation, hence allowing a correlation test. For all data sets that we evaluated, and the three most commonly used low-level processing procedures including MAS5, RMA and MBEI, the housekeeping-gene normalization failed the test. For a real clinical data set, RMA and MBEI showed significant correlation for absent genes. We also found that a second round of normalization on the probe set level improved normalization significantly throughout. Conclusion Previous evaluation of low-level processing in the literature has been limited to artificial spike-in and mixture data sets. In the absence of a known gold-standard, the correlation criterion allows us to assess the appropriateness of low-level processing of a specific data set and the success of normalization for subsets of genes.

  1. CORRELATION OF BREAST CANCER AND SERUM HIGH DENSITY LIPOPROTEIN CHOLESTEROL LEVEL: A SINGLE CENTRE STUDY

    Anjali

    2015-12-01

    Full Text Available Breast cancer is the most common site specific cancer in women. Lots of etiological factors have been suggested regarding its causation. The risk is influenced by obesity, parity, exogenous and endogenous hormones, exposure to chemicals and radiation and many more. Various studies suggest that as HDL-C seems to be cardio protective, it is also protective for breast cancer. Serum HDL-C levels are found to be low in breast cancer patients. We studied this hypothesis in local population of Southern Rajasthan and nearby region to see if low serum HDL-C is associated with increased risk of breast cancer. We studied serum HDL-C level in 50 female patients of breast cancer along with their menopausal status and compared it to their respective controls. We found that breast cancer patients had significantly low level of serum HDL-C and presented in advanced stage of cancer. It supports that low serum HDL-C level is associated with increased risk of breast cancer. So one should think about those dietary and lifestyle measures, which maintain high serum HDL-C level so that it might become preventive measure for breast cancer.

  2. Immobilization of actinides and fission products in Synroc

    Synroc containing simulated JW-A waste decreased in density as it sustained radiation damage due to doping with 0.69 wt% of 244Cm. The rate of change in density with increasing α-fluence showed an increase beyond ∼9.5 x 1017 αg-1, and the increase may reflect the onset of intergranular cracking. This may also explain the increases in leach rates of many elements above about the same α-fluence. Additional leach rate increases were deduced to occur in the perovskite phase as a result of intragranular radiation damage. Leach rates of Np, Pu, Am, and Cm were found to be much lower than the matrix elements. Nd3+ and U4+ incorporation in the very durable zirconolite phase is extensive suggesting that it is suitable for actinide encapsulation. (author)

  3. On a fast reactor cycle scheme that incorporates a thoria-based minor actinide-containing cermet fuel

    A fast reactor cycle scheme that incorporates a thoria-based minor actinide-containing cermet fuel is given. The present cermet fuel consists of an oxide solid solution of Th and minor actinides and Mo-inert matrix. It has been proposed as a high-performance device that can enhance minor actinide incineration in a fast reactor cycle. It is used in an independent small sub-cycle, whereby dedicated cycle technologies are adopted. Two-step reprocessing process was proposed for the present cermet fuel; it consists of a pre-removal of Mo-inert matrix and an actinide recovery. A preliminary test for the pre-removal of Mo-inert matrix was carried out using a surrogate cermet fuel. Burnup characteristics of a fast reactor core loaded with the cermet fuel were investigated by using neutronic calculation codes. It was revealed that a heterogeneous composition of Mo-inert in inner and outer cores may lead to an effective transmutation of minor actinides and a flattered power density. It was concluded that the present cermet fuel was potentially promising as a high-performance incineration device of minor actinides for fast reactors. (author)

  4. In vitro studies of actinides and alveolar macrophages

    The toxicity of 239PuO2, 239Pu(NO3)4, and 241AmO2 to rabbit alveolar macrophages in culture was assessed. Comparison of toxicity of 239Pu(NO3)4 and 241AmO2 at the same radiation dose level indicates toxicity is due to radiation and not the chemical form of the actinide. Investigations were begun to determine the effect of serum macrophages and DTPA on 241AmO2 solubility

  5. Gastrointestinal absorption of actinides: a review with special reference to primate data

    Large scale geological burial of transuranic wastes from fission power production may expose segments of future generations to trace amounts of actinides in water and food, which, via gastrointestinal absorption, could result in internal doses of alpha radiation. Gastrointestinal absorption of actinide elements is a poorly understood process. Experimental studies, primarily using rodents, often produce ambiguous results with order of magnitude fluctuations in estimates of GI absorption. Since experimental conditions like the chemical form of the fed actinides or reducing and complexing capacity of the stomach content, influence the GI transfer factor in seemingly unpredictable ways, only a better understanding of events at the molecular level will enable more reliable predictions to be made of the organ burdens resulting from actinides passing through the digestive tract. From a review of the existing literature it is apparent that in vitro research data in the area of GI uptake mechanisms (i.e. transport mediated by ion carriers in body fluids and across cell membranes) are virtually non-existant. In view of the uncertainties linked to in vivo uptake experiment, models which approximate man, i.e. derived from non-human primate studies, should be the best choice of experimental systems in which to determine reliable estimates for gastrointestinal transfer factors of actinide elements. (Auth.)

  6. Status of development of actinide blanket processing flowsheets for accelerator transmutation of nuclear waste

    An accelerator-driven subcritical nuclear system is briefly described that transmutes actinides and selected long-lived fission products. An application of this accelerator transmutation of nuclear waste (ATW) concept to spent fuel from a commercial nuclear power plant is presented as an example. The emphasis here is on a possible aqueous processing flowsheet to separate the actinides and selected long-lived fission products from the remaining fission products within the transmutation system. In the proposed system the actinides circulate through the thermal neutron flux as a slurry of oxide particles in heavy water in two loops with different average residence times: one loop for neptunium and plutonium and one for americium and curium. Material from the Np/Pu loop is processed with a short cooling time (5-10 days) because of the need to keep the total actinide inventory, low for this particular ATW application. The high radiation and thermal load from the irradiated material places severe constraints on the separation processes that can be used. The oxide particles are dissolved in nitric acid and a quarternary, ammonium anion exchanger is used to extract neptunium, plutonium, technetium, and palladium. After further cooling (about 90 days), the Am, Cm and higher actinides are extracted using a TALSPEAK-type process. The proposed operations were chosen because they have been successfully tested for processing high-level radioactive fuels or wastes in gram to kilogram quantities

  7. Partitioning technologies and actinide science: towards pilot facilities in Europe (ACSEPT project)

    ACSEPT is an essential contribution to the demonstration, in the long term, of the potential benefits of actinide recycling to minimize the burden on the geological repositories. To succeed, ACSEPT is organized into three technical domains: (i) Considering technically mature aqueous separation processes, ACSEPT works to optimize and select the most promising ones dedicated either to actinide partitioning or to grouped actinide separation. A substantial review was undertaken either to be sure that the right molecule families are being studied, or, on the contrary, to identify new candidates. Results of the first hot tests allowed the validation of some process options. (ii) Concerning pyrochemical separation processes, ACSEPT is focused on the enhancement of the two reference cores of process selected within EUROPART with specific attention to the exhaustive electrolysis in molten chloride (quantitative recovery of the actinides with the lowest amount of fission products) and to actinide back-extraction from an An-Al alloy. R and D efforts are also brought to key scientific and technical issues compulsory for building a complete separation process (head-end steps, salt treatment for recycling and waste management). (iii) By integrating all the experimental results within engineering and systems studies, both in hydro and pyro domains, ACSEPT will deliver relevant flowsheets and recommendations to prepare for future demonstration at a pilot level, in relation with strategies developed through the SNE-TP. In addition, a training and education programme is implemented to share the knowledge among the partitioning community and the future generations of researchers

  8. Modelling energy level alignment at organic interfaces and density functional theory

    Flores, F.; Ortega, J.; Vazquez, Patricia

    2009-01-01

    qualitatively and semiquantitatively the barrier height formation at those interfaces. The IDIS model, governed by the organic CNL (charge neutrality level) and the interface screening includes: (a) charge transfer across the interface; (b) the "pillow'' (or Pauli) effect associated with the compression of the...

  9. Oxidized low density lipoprotein increases RANKL level in human vascular cells. Involvement of oxidative stress

    Highlights: •Oxidized LDL enhances RANKL level in human smooth muscle cells. •The effect of OxLDL is mediated by the transcription factor NFAT. •UVA, H2O2 and buthionine sulfoximine also increase RANKL level. •All these effects are observed in human fibroblasts and endothelial cells. -- Abstract: Receptor Activator of NFκB Ligand (RANKL) and its decoy receptor osteoprotegerin (OPG) have been shown to play a role not only in bone remodeling but also in inflammation, arterial calcification and atherosclerotic plaque rupture. In human smooth muscle cells, Cu2+-oxidized LDL (CuLDL) 10–50 μg/ml increased reactive oxygen species (ROS) and RANKL level in a dose-dependent manner, whereas OPG level was not affected. The lipid extract of CuLDL reproduced the effects of the whole particle. Vivit, an inhibitor of the transcription factor NFAT, reduced the CuLDL-induced increase in RANKL, whereas PKA and NFκB inhibitors were ineffective. LDL oxidized by myeloperoxidase (MPO-LDL), or other pro-oxidant conditions such as ultraviolet A (UVA) irradiation, incubation with H2O2 or with buthionine sulfoximine (BSO), an inhibitor of glutathione synthesis, also induced an oxidative stress and enhanced RANKL level. The increase in RANKL in pro-oxidant conditions was also observed in fibroblasts and endothelial cells. Since RANKL is involved in myocardial inflammation, vascular calcification and plaque rupture, this study highlights a new mechanism whereby OxLDL might, by generation of an oxidative stress, exert a deleterious effect on different cell types of the arterial wall

  10. Minior Actinide Doppler Coefficient Measurement Assessment

    Nolan E. Hertel; Dwayne Blaylock

    2008-04-10

    The "Minor Actinide Doppler Coefficient Measurement Assessment" was a Department of Energy (DOE) U-NERI funded project intended to assess the viability of using either the FLATTOP or the COMET critical assembly to measure high temperature Doppler coefficients. The goal of the project was to calculate using the MCNP5 code the gram amounts of Np-237, Pu-238, Pu-239, Pu-241, AM-241, AM-242m, Am-243, and CM-244 needed to produce a 1E-5 in reactivity for a change in operating temperature 800C to 1000C. After determining the viability of using the assemblies and calculating the amounts of each actinide an experiment will be designed to verify the calculated results. The calculations and any doncuted experiments are designed to support the Advanced Fuel Cycle Initiative in conducting safety analysis of advanced fast reactor or acceoerator-driven transmutation systems with fuel containing high minor actinide content.

  11. Separation of actinides with alkylpyridinium salts

    Various f-elements are separated as anionic complexes from both acidic and alkaline solutions by precipitation with alkylpyridinium salts. The precipitates are also cationic surfactants where the simple counter-ion (e.g. nitrate or chloride) is replaced by the negatively charged complex anion of an actinide or lanthanide. The low solubility of these precipitates is explained by a strong affinity of divalent complex counter-ions of f-elements to the quaternary nitrogen. Precipitations in solutions of nitric acid allow to separate tetravalent f-elements from other metals, in alkaline carbonate solutions tetravalent and hexavalent actinides are precipitated simultaneously. The last procedure yields precipitates, which are very intimate mixtures of hexavalent and tetravalent actinides. This allows to prepare mixed oxides in a simple way. (author) 6 refs.; 3 figs.; 3 tabs

  12. Neutron scattering studies of the actinides

    The electronic structure of actinide materials presents a unique example of the interplay between localized and band electrons. Together with a variety of other techniques, especially magnetization and the Mossbauer effect, neutron studies have helped us to understand the systematics of many actinide compounds that order magnetically. A direct consequence of the localization of 5f electrons is the spin-orbit coupling and subsequent spin-lattice interaction that often leads to strongly anisotropic behavior. The unusual phase transition in UO2, for example, arises from interactions between quadrupole moments. On the other hand, in the monopnictides and monochalcogenides, the anisotropy is more difficult to understand, but probably involves an interaction between actinide and anion wave functions. A variety of neutron experiments, including form-factor studies, critical scattering and measurements of the elementary excitations have now been performed, and the conceptual picture emerging from these studies will be discussed

  13. Coordination chemistry for new actinide separation processes

    The amount of wastes and the number of chemical steps can be decreased by replacing the PUREX process extractant (TBP) by, N.N- dialkylamides (RCONR'2). Large amounts of deep underground storable wastes can be stored into sub-surface disposals if the long lived actinide isotopes are removed. Spent nuclear fuels reprocessing including the partitioning of the minor actinides Np, Am, Cm and their transmutation into short half lives fission products is appealing to the public who is not favorable to the deep underground storage of large amounts of long half lived actinide isotopes. In this paper coordination chemistry problems related to improved chemical separations by solvent extraction are presented. 2 tabs.; 4 refs

  14. Research on Actinides in Nuclear Fuel Cycles

    The electrochemical/spectroscopic integrated measurement system was designed and set up for spectro-electrochemical measurements of lanthanide and actinide ions in high temperature molten salt media. A compact electrochemical cell and electrode system was also developed for the minimization of reactants, and consequently minimization of radioactive waste generation. By applying these equipment, oxidation and reduction behavior of lanthanide and actinide ions in molten salt media have been made. Also, thermodynamic parameter values are determined by interpreting the results obtained from electrochemical measurements. Several lanthanide ions exhibited fluorescence properties in molten salt. Also, UV-VIS measurement provided the detailed information regarding the oxidation states of lanthanide and actinide ions in high temperature molten salt media

  15. Level-density parameters in the back-shifted Fermi gas model

    The parameters a and δeff appearing in the back-shifted Fermi gas model are determined for about 3000 nuclei on the basis of modern estimated experimental data and the proposed systematics. For 272 of these nuclei, the parameters are deduced from experimental data on the cumulative numbers of low-lying levels and on mean spacings between S-wave neutron resonances at the neutron binding energy in the nuclei. For 952 nuclei, the parameter δeff is calculated by using the cumulative numbers of low-lying levels and values of the parameter a that were obtained via an interpolation from the points corresponding to the aforementioned 272 nuclei. For the remaining nuclei, the parameters a and δeff are obtained on the basis of the proposed systematics. An expression is constructed for taking into account the damping of shell effects with increasing excitation energy of nuclei. The results are compared with those from other studies

  16. Macular pigment optical density and its relationship with serum and dietary levels of lutein and zeaxanthin

    BEATTY, S; Nolan, John; Kavanagh, H.; O'Donovan, O. M.

    2004-01-01

    Observational evidence is accumulating that the onset of age-related maculopathy, the leading cause of legal blindness in the Western World, could be delayed, or even averted, with antioxidant supplements. Lutein (L) and zeaxanthin (Z) are two hydroxycarotenoids with antioxidant activity which accumulate at the macula, where they are collectively known as macular pigment (MP). It has been shown that MP is entirely of dietary origin, and that L and Z levels in serum, diet, and retina correlate...

  17. CORRELATION OF BREAST CANCER AND SERUM HIGH DENSITY LIPOPROTEIN CHOLESTEROL LEVEL: A SINGLE CENTRE STUDY

    Anjali; Deepak

    2015-01-01

    Breast cancer is the most common site specific cancer in women. Lots of etiological factors have been suggested regarding its causation. The risk is influenced by obesity, parity, exogenous and endogenous hormones, exposure to chemicals and radiation and many more. Various studies suggest that as HDL-C seems to be cardio protective, it is also protective for breast cancer. Serum HDL-C levels are found to be low in breast cancer patients. We studied this hypothesis in local population of South...

  18. Hot test of a TALSPEAK procedure for separation of actinides and lanthanides using recirculating DTPA-lactic acid solution

    Results are reported from a hot test of a TALSPEAK type process for separation of higher actinides (Am, Cm) from lanthanides. Actinides and lanthanides are extracted by 1 M HDEHP and separated by selective strip of the actinides, using a mixture of DTPA and lactic acid (reversed TALSPEAK process). In order to minimize the generation of secondary waste, a procedure using recirculating DTPA-Lactic acid solution has been developed. A separation factor between Am and Eu of 132 was achieved. In regard to separations of Am and Cm from commercial HLLW (high level liquid wastes), the factor corresponds to 1.5% of the lanthanide group remaining with the actinides. The loss of Am was about 0.2%. 9 figures, 3 tables

  19. Actinide elements in aquatic and terrestrial environments

    Progress is reported on the following research projects: water-sediment interactions of U, Pu, Am, and Cm; relative availability of actinide elements from abiotic to aquatic biota; comparative uptake of transuranic elements by biota bordering Pond 3513; metabolic reduction of 239Np from Np(V) to Np(IV) in cotton rats; evaluation of hazards associated with transuranium releases to the biosphere; predicting Pu in bone; adsorption--solubility--complexation phenomena in actinide partitioning between sorbents and solution; comparative soil extraction data; and comparative plant uptake data

  20. Sequential analysis of selected actinides in urine

    The monitoring of personnel by urinalysis for suspected contamination by actinides necessitated the development and implementation of an analytical scheme that will separate and identify alpha emitting radionuclides of these elements. The present work deals with Pu, Am, and Th. These elements are separated from an ashed urine sample by means of coprecipitation and ion exchange techniques. The final analysis is carried out by electroplating the actinides and counting in a α-spectrometer. Mean recoveries of these elements from urine are: Pu 64%, Am 74% and Th 69%. (auth)

  1. Spin-Orbit Coupling in Actinide Cations

    Bagus, Paul S.; Ilton, Eugene S.; Martin, Richard L.; Jensen, Hans Jorgen A.; Knecht, Stefan

    2012-09-01

    The limiting case of Russell-Saunders coupling, which leads to a maximum spin alignment for the open shell electrons, usually explains the properties of high spin ionic crystals with transition metals. For actinide compounds, the spin-orbit splitting is large enough to cause a significantly reduced spin alignment. Novel concepts are used to explain the dependence of the spin alignment on the 5f shell occupation. We present evidence that the XPS of ionic actinide materials may provide direct information about the angular momentum coupling within the 5f shell.

  2. Spin-orbit coupling in actinide cations

    Bagus, Paul S.; Ilton, Eugene S.; Martin, Richard L.; Jensen, Hans Jørgen Aa.; Knecht, Stefan

    2012-09-01

    The limiting case of Russell-Saunders coupling, which leads to a maximum spin alignment for the open shell electrons, usually explains the properties of high spin ionic crystals with transition metals. For actinide compounds, the spin-orbit splitting is large enough to cause a significantly reduced spin alignment. Novel concepts are used to explain the dependence of the spin alignment on the 5f shell occupation. We present evidence that the XPS of ionic actinide materials may provide direct information about the angular momentum coupling within the 5f shell.

  3. Actinide and fission product separation and transmutation

    NONE

    1993-07-01

    The second international information exchange meeting on actinide and fission product separation and transmutation, took place in Argonne National Laboratory in Illinois United States, on 11-13 November 1992. The proceedings are presented in four sessions: Current strategic system of actinide and fission product separation and transmutation, progress in R and D on partitioning processes wet and dry, progress in R and D on transmutation and refinements of neutronic and other data, development of the fuel cycle processes fuel types and targets. (A.L.B.)

  4. Actinide phosphonate complexes in aqueous solutions

    Complexes formed by actinides with carboxylic acids, polycarboxylic acids, and aminopolycarboxylic acids play a central role in both the basic and process chemistry of the actinides. Recent studies of f-element complexes with phosphonic acid ligands indicate that new ligands incorporating doubly ionizable phosphonate groups (-PO3H2) have many properties which are unique chemically, and promise more efficient separation processes for waste cleanup and environmental restoration. Simple diphosphonate ligands form much stronger complexes than isostructural carboxylates, often exhibiting higher solubility as well. In this manuscript recent studies of the thermodynamics and kinetics of f-element complexation by 1,1 and 1,2 diphosphonic acid ligands are described

  5. Actinide and fission product separation and transmutation

    The second international information exchange meeting on actinide and fission product separation and transmutation, took place in Argonne National Laboratory in Illinois United States, on 11-13 November 1992. The proceedings are presented in four sessions: Current strategic system of actinide and fission product separation and transmutation, progress in R and D on partitioning processes wet and dry, progress in R and D on transmutation and refinements of neutronic and other data, development of the fuel cycle processes fuel types and targets. (A.L.B.)

  6. Response of actinides to flux changes in high-flux systems

    When discussing the transmutation of actinides in accelerator-based transmutation of waste (ATW) systems, there has been some concern about the dynamics of the actinides under high transient fluxes. For a pure neptunium feed, it has been estimated that the 238Np/237Np ratio increase due to an increasing flux may lead to an unstable, positive reactivity growth. In this analysis, a perturbation method is used to calculate the response of the entire set of actinides in a general way that allows for more species than just neptunium. The time response of the system can be calculated; i.e., a plot of fuel composition and reactivity versus time after a change in flux can be made. The effects of fission products can also be included. The procedure is extremely accurate on short time scales (∼ 1000 s) for the flux levels we contemplate. Calculational results indicate that the reactivity insertions are always smaller than previously estimated

  7. Ultra-trace analytical techniques for internal dosimetry of actinides: an appraisal

    This paper briefly reviews and summarises the currently available analytical techniques employed in internal dosimetry for the determination of important actinides 232Th, 238U and 239,240Pu in bio-assay samples. The techniques covered are neutron activation analysis (NAA), delayed neutron activation analysis (DNAA), alpha spectrometry, spectrophotometry, fluorimetry, kinetic phosphorescence, solid state nuclear track detector (SSNTD), fission track analysis (FTA), inductively coupled plasma-mass spectrometry (ICP-MS) and anodic/adsorptive striping voltametry (ASV). A comparison is made for the detection limits of various techniques for individual actinides in terms of the fraction/multiple of the derived urinary excretion levels such as DRL and DIL. Advantages and limitations of each technique have been discussed and conclusions regarding the most suitable technique for each actinide are reported. (author). 20 refs., 3 tabs

  8. Engineering assessment studies on the JRC's actinides partitioning processes for transmutation

    Three conceptual processes have been studied and investigated for the feasibility of removing actinides from high active waste. Two of the flowsheets rely completely on counter current techniques for the actinides separation namely the TBP and HDEHP processes, whereas the third process OXAL, uses a precipitation technique in the first instance followed by dissolution of the actinides and rare-earths (RE) for further treatment using a modified HDEHP process. Many important factors such as 'direct' or 'delayed', concentrated or unconcentrated HAW, storage time, activity and heat release levels, solvent irradiation DF's, safety and steady-state recycling conditions for U-LWR, Pu-LWR and FBRs for possible transmutation scenarios have been taken into consideration

  9. Synthesis and Evaluation of new Polyfunctional Molecules for Group Actinide Extraction; Synthese et evaluation de Nouvelles Molecules Polyfonctionnelles pour la Separation Groupee des Actinides

    Marie, C.

    2009-10-15

    The aim of this project is to design new extracting molecules for spent nuclear fuel reprocessing. In order to minimize the long-term residual radiotoxicity of the waste, the GANEX process is an option based on homogeneous recycling of actinides. All actinides (U, Np, Pu, Am, Cm), present in a highly acidic aqueous solution, would be extracted together and separated from fission products (especially from lanthanides) using liquid-liquid extraction. In this context, twenty new bi-topic ligands constituted of a nitrogen poly-aromatic unit functionalized by amide groups were synthesized. Liquid-liquid extraction tests with these ligands dissolved alone in the organic phase show that N, N, N', N'-tetra-alkyl-6, 6''(2, 2':6', 2''-terpyridine)-diamides are able to selectively extract actinides at different oxidation states (Np(V et VI), U(VI), Pu(IV), Am(III), Cm(III)) from an aqueous solution 3M HNO{sub 3}. Nevertheless, actinides(III) are poorly extracted. According to crystallographic structures of complexes with Nd(III) and U(VI) determined by X-rays diffraction, these ligands are penta-dentate. In solution (methanol), complexes stoichiometries (1:1) of Nd(III), U(VI) and Pu(IV) were determined by electro-spray ionization mass spectrometry. Stability constants, evaluated by UV-visible spectrophotometry in MeOH/H{sub 2}O solutions, confirm the selectivity of ligands toward actinides(III) with respect to lanthanides(III). Associate to nuclear magnetic resonance experiments and DFT calculations (Density Functional Theory), a better knowledge of their coordination mode was achieved. (author)

  10. Microvessel density at different levels of normal or injured bile duct in dogs and its surgical implications

    LinGeng; DingLuo; Hao-ChunZhang; Liang-SongZhao; De-KeQing

    2011-01-01

    BACKGROUND: Ischemic recurrent stricture after surgical repair for iatrogenic bile duct injury (BDI) remains a challenge in clinical practice. The present study was designed to investigate whether ischemia is universal and of varied severity at different levels of the proximal bile duct after BDI. METHODS: A total of 30 beagle dogs were randomly divided into control, BDI, and BDI-repaired groups. The BDI animal model was established based on the classic pattern of laparoscopic cholecystectomy-related BDI. The animals were sacrificed on postoperative day 15, and bile duct tissue was harvested to assess microvessel density (MVD) at selected levels of the normal, post-BDI and BDI-repaired bile duct with the CD34 immunohistochemistry technique. RESULTS:  In the control group, MVD at level H (high level) was remarkably higher than that at level L (low level). No significant difference was found between MVDs at levels H and M (middle level), as well as at levels M and L. However, the tendency was noted that the closer the level to the hilus, the greater the MVD at that level. In both the BDI and BDI-repaired groups, MVDs at level H were generally greater than those at level L, despite the unremarkable differences between MVDs at neighboring levels. In these two groups, a similar tendency of MVD distribution to that in the control group was found; the closer the level to the injury site, the lower was the MVD at that level. Moreover, compared with the MDVs at the levels M and L in the control group, MVDs at the corresponding levels in the BDI and BDI-repaired groups were all remarkably reduced (P CONCLUSIONS: After BDI, universal ischemic damage in the injured proximal bile duct develops close to the injury site, while close to the hilus, ischemia is relatively slight. High hepaticojejunostomy, rather than low biloenterostomy or end-to-end duct anastomosis, should be recommended for BDI repair. Great care should be taken to protect the peribiliary plexus during

  11. Permanganate Reduction of Savannah River Site Actual Waste Samples for Strontium and Actinides Removal

    The authors investigated the performance of permanganate treatment for the removal of strontium and actinides from actual high-level waste. Researchers also conducted comparison tests with monosodium titanate (MST) as a means of evaluating the permanganate performance. Tests utilized a Tank 37H/44F composite waste solution. Personnel significantly increased the concentration of alpha emitting actinides in the waste by the addition of acidic americium/curium solution (F-Canyon Tank 17.1 solution), which contained a significant quantity of plutonium, and neptunium-237 stock solution. Tests examined three permanganate treatment options

  12. Optical spectra and electronic structure of actinide ions in compounds and in solution

    This report provides a summary of theoretical and experimental studies of actinide spectra in condensed phases. Much of the work was accomplished at Argonne National Laboratory, but references to related investigations by others are included. Spectroscopic studies of the trivlent actinides are emphasized, as is the use of energy level parameters, evaluated from experimental data, to investigate systematic trends in electronic structure and other properties. Some reference is made to correlations with atomic spectra, as well as with spectra of the (II), (IV), and higher valence states. 207 refs., 39 figs., 38 tabs

  13. Multiple diglycolamide functionalized ligands in room temperature ionic liquids: 'green' solvents for actinide partitioning

    Multiple-diglycolamide-functionalized ligands (MDGA) in room temperature ionic liquids (RTILs) were studied for extraction of actinides and lanthanides from aqueous acidic solutions. The extraction kinetics, separation behavior, associated thermodynamics of extraction, nature of the extracted species formed were studied. Luminescence spectroscopy was used to understand the nature of bonding between metal and ligands, formation of inner sphere/outer sphere complex etc. The radiolytic stability of solvent systems was studied and attempt was made to understand the degradation products. Finally, all the systems were evaluated for 'actinide partitioning' from synthetic high level liquid waste solution (HLLW). (author)

  14. Sensitivity of ICP-MS, PERALS and alpha spectrometry for the determination of actinides

    The purpose of this study was to compare the sensitivity of the three most popular techniques for the determination of minor actinides at environmental levels: ICP-MS, PERALS and solid state alpha spectrometry. For each method the limit of detection and the resolution were estimated in order to study the content and isotopic composition of the actinides. The sensitivities of the three determination techniques were compared. Two international reference materials, IAEA-135 (Irish Sea sediment) and IAEA-300 (Baltic Sea sediment) were analyzed for activity concentrations of 238Pu, 239Pu, 240Pu, 241Pu and 241Am. (authors)

  15. Spin Measurements of n+Sr-87 for Level Density Studies

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

    2014-01-01

    We have used the 4 pi BaF2 gamma-ray detector array at the n\\_TOF neutron time-of-flight facility at CERN for an experiment in order to determine the spins of resonances of n+Sr-87 by measuring the gamma-ray spectra and multiplicity distributions. The first results are presented here. We have assigned the orbital momentum l to all evaluated resonances on the basis of their neutron widths. Further we have assigned the spin J to 16 s-wave resonances on based the population of low-lying levels.

  16. Relation of Vitamin B12 Levels to Bone Mineral Density of Postmenopausal Women - Original Investigation

    Nur Kesiktaş; Nurten Eskiyurt; Ayşe Karan; Semih Akı; Halim İşsever

    2009-01-01

    Aim: Although vitamin B12 (vit-B12) is known to influence the hemopoeitic and nervous systems, little is known about the skeletal effects of vit-B12. Researchs that demonstrated an association between serum vitamin B-12 concentration and osteoblastic function and its’ role in DNA synthesis, which suggesting a relationship between osteoporosis, this randomized controlled trial were planned. Material and Methods: Vit-B12 levels of 740 patients aged between 50-65 years, who were applied to ou...

  17. Impact of serum amyloid A on high density lipoprotein composition and levels

    de Beer, Maria C.; Webb, Nancy R.; Joanne M. Wroblewski; Noffsinger, Victoria P.; Debra L Rateri; Ji, Ailing; van der Westhuyzen, Deneys R.; De Beer, Frederick C.

    2010-01-01

    Serum amyloid A (SAA) is an acute-phase protein mainly associated with HDL. To study the role of SAA in mediating changes in HDL composition and metabolism during inflammation, we generated mice in which the two major acute-phase SAA isoforms, SAA1.1 and SAA2.1, were deleted [SAA knockout (SAAKO) mice], and induced an acute phase to compare lipid and apolipoprotein parameters between wild-type (WT) and SAAKO mice. Our data indicate that SAA does not affect apolipoprotein A-I (apoA-I) levels o...

  18. The kinetics of alpha-decay-induced amorphization in zircon and apatite containing weapons-grade plutonium or other actinides

    Zircon and apatite form as actinide host phases in several high-level waste forms and have been proposed as host phases for the disposition of excess weapons-grade Pu and other actinides. Additionally, closely-related structure types appear as actinide-bearing phases among the corrosion products of spent nuclear fuel and high-level waste glasses. Self-radiation damage from α-decay of the incorporated Pu or other actinides can affect the durability and performance of these actinide-bearing phases. For both zircon and apatite, these effects can be modeled as functions of storage time and repository temperature and validated by comparison with data from natural occurrences. Natural zircons and apatites, with ages up to 4 billion years, provide abundant evidence for their long-term durability because of their wide spread use in geochronology and fission-track dating. Detailed studies of natural zircons and apatites, 238Pu-containing zircon, a 244Cm-containing silicate apatite, and ion-irradiated zircon, natural apatite and synthetic silicate apatites provide a unique basis for the analysis of α-decay effects over broad time scales. Models for α-decay effects in zircon and apatite are developed that show α-decay of Pu and other actinides will lead to a crystalline-to-amorphous transformation in zircon, but not in apatite, under conditions typical of a repository, such as the Yucca Mountain site. (orig.)

  19. Variation of DNA Fragmentation Levels During Density Gradient Sperm Selection for Assisted Reproduction Techniques

    Muratori, Monica; Tarozzi, Nicoletta; Cambi, Marta; Boni, Luca; Iorio, Anna Lisa; Passaro, Claudia; Luppino, Benedetta; Nadalini, Marco; Marchiani, Sara; Tamburrino, Lara; Forti, Gianni; Maggi, Mario; Baldi, Elisabetta; Borini, Andrea

    2016-01-01

    Abstract Predicting the outcome of in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) is one main goal of the present research on assisted reproduction. To understand whether density gradient centrifugation (DGC), used to select sperm, can affect sperm DNA integrity and impact pregnancy rate (PR), we prospectively evaluated sperm DNA fragmentation (sDF) by TUNEL/PI, before and after DGC. sDF was studied in a cohort of 90 infertile couples the same day of IVF/ICSI treatment. After DGC, sDF increased in 41 samples (Group A, median sDF value: 29.25% [interquartile range, IQR: 16.01–41.63] in pre- and 60.40% [IQR: 32.92–93.53] in post-DGC) and decreased in 49 (Group B, median sDF value: 18.84% [IQR: 13.70–35.47] in pre- and 8.98% [IQR: 6.24–15.58] in post-DGC). PR was 17.1% and 34.4% in Group A and B, respectively (odds ratio [OR]: 2.58, 95% confidence interval [CI]: 0.95–7.04, P = 0.056). After adjustment for female factor, female and male age and female BMI, the estimated OR increased to 3.12 (95% CI: 1.05–9.27, P = 0.041). According to the subgroup analysis for presence/absence of female factor, heterogeneity in the association between the Group A and B and PR emerged (OR: 4.22, 95% CI: 1.16–15.30 and OR: 1.53, 95% CI: 0.23–10.40, respectively, for couples without, n = 59, and with, n = 31, female factor). This study provides the first evidence that the DGC procedure produces an increase in sDF in about half of the subjects undergoing IVF/ICSI, who then show a much lower probability of pregnancy, raising concerns about the safety of this selection procedure. Evaluation of sDF before and after DGC configures as a possible new prognostic parameter of pregnancy outcome in IVF/ICSI. Alternative sperm selection strategies are recommended for those subjects who undergo the damage after DGC. PMID:27196465

  20. Changes of bone density and serum osteocalcin levels in mid and late pregnancy

    Single photon bone densitometer has been used to determine the bone mineral contents in 1521 cases of mid and late pregnant women. The results showed that the contents are significantly lower than the normal group (P<0.001). Varying degrees of bone mineral loss took place in 488 cases (32.1%) of pregnant women. Serum osteocalcin (BGP) levels in 40 cases of normal nonpregnant women and 41 cases of the bone mineral loss group of pregnant women have been measured simultaneously. The results showed that the contents of the bone mineral loss group of pregnant women are obviously lower than the normal group (P<0.001). This fact implies that the determinations of single photon bone densitometer and serum BGP RIA can be used as the indices for assessing the bone mineral loss in pregnant women

  1. Znf202 affects high density lipoprotein cholesterol levels and promotes hepatosteatosis in hyperlipidemic mice.

    Carlos L J Vrins

    Full Text Available BACKGROUND: The zinc finger protein Znf202 is a transcriptional suppressor of lipid related genes and has been linked to hypoalphalipoproteinemia. A functional role of Znf202 in lipid metabolism in vivo still remains to be established. METHODOLOGY AND PRINCIPAL FINDINGS: We generated mouse Znf202 expression vectors, the functionality of which was established in several in vitro systems. Next, effects of adenoviral znf202 overexpression in vivo were determined in normo- as well as hyperlipidemic mouse models. Znf202 overexpression in mouse hepatoma cells mhAT3F2 resulted in downregulation of members of the Apoe/c1/c2 and Apoa1/c3/a4 gene cluster. The repressive activity of Znf202 was firmly confirmed in an apoE reporter assay and Znf202 responsive elements within the ApoE promoter were identified. Adenoviral Znf202 transfer to Ldlr-/- mice resulted in downregulation of apoe, apoc1, apoa1, and apoc3 within 24 h after gene transfer. Interestingly, key genes in bile flux (abcg5/8 and bsep and in bile acid synthesis (cyp7a1 were also downregulated. At 5 days post-infection, the expression of the aforementioned genes was normalized, but mice had developed severe hepatosteatosis accompanied by hypercholesterolemia and hypoalphalipoproteinemia. A much milder phenotype was observed in wildtype mice after 5 days of hepatic Znf202 overexpression. Interestingly and similar to Ldl-/- mice, HDL-cholesterol levels in wildtype mice were lowered after hepatic Znf202 overexpression. CONCLUSION/SIGNIFICANCE: Znf202 overexpression in vivo reveals an important role of this transcriptional regulator in liver lipid homeostasis, while firmly establishing the proposed key role in the control of HDL levels.

  2. Reduced plasma adiponectin levels relative to oxidized low density lipoprotein and nitric oxide in coronary artery disease patients

    Gholam Basati

    2011-01-01

    Full Text Available INTRODUCTION: Adiponectin is a circulating hormone that is produced exclusively by adipocytes and has antiinflammatory and anti-atherogenic properties. The hypothesis that there are differences in adiponectin levels between stable and unstable coronary-artery disease patients remains controversial. Furthermore, the potential relationships between the plasma adiponectin level and the inflammatory and non-inflammatory markers (oxidized low density lipoprotein and nitric oxide in patients with stable and unstable coronary-artery disease relative to normal subjects have not been assessed. OBJECTIVES: To assess whether plasma adiponectin levels differ among patients with stable and unstable coronary-artery disease and among control subjects, and to correlate plasma adiponectin level with inflammatory and clinical risk factors (such as oxidized-LDL and nitric oxide in these patients. METHODS: This study included 50 control subjects, 50 stable angina patients and 50 unstable angina patients with angiographically documented coronary-artery disease. Plasma adiponectin and oxidized-LDL levels were determined using an enzyme immunoassay. Plasma nitric oxide, high sensitivity C-reactive protein and lipid profile levels were also measured. RESULTS: Plasma adiponectin levels were lower in the unstable angina patients (4.9 ± 1.30 µg/mL than in the stable angina patients (6.34 ± 1.0 µg/mL or in the controls (9.25 ± 1.8 µg/mL; these levels were also significantly lower in stable angina patients versus controls (p<0.001. Plasma adiponectin levels were negatively correlated with oxidized-LDL, high sensitivity C-reactive protein, lipid profile and other clinical risk factors but positively correlated with nitric oxide. CONCLUSION: Plasma adiponectin levels were found to be lower in both stable and unstable angina patients relative to control subjects, and the correlation between plasma adiponectin and cardiovascular markers is weakened in these patients.

  3. Chemical compatibility of HLW borosilicate glasses with actinides

    During liquid storage of HLLW the formation of actinide enriched sludges is being expected. Also during melting of HLW glasses an increase of top-to-bottom actinide concentrations can take place. Both effects have been studied. Besides, the vitrification of plutonium enriched wastes from Pu fuel element fabrication plants has been investigated with respect to an isolated vitrification process or a combined one with the HLLW. It is shown that the solidification of actinides from HLLW and actinide waste concentrates will set no principal problems. The leaching of actinides has been measured in salt brine at 230C and 1150C. (orig.)

  4. Actinide recycle in LMFBRs as a waste management alternative

    Beaman, S.L.

    1979-08-21

    A strategy of actinide burnup in fast reactor systems has been investigated as an approach for reducing the long term hazards and storage requirements of the actinide waste elements and their decay daughters. The actinide recycle studies also included plutonium burnup studies in the event that plutonium is no longer required as a fuel. Particular emphasis was placed upon the timing of the recycle program, the requirements for separability of the waste materials, and the impact of the actinides on the reactor operations and performance. It is concluded that actinide recycle and plutonium burnout are attractive alternative waste management concepts. 25 refs., 14 figs., 34 tabs.

  5. Actinide recycle in LMFBRs as a waste management alternative

    A strategy of actinide burnup in fast reactor systems has been investigated as an approach for reducing the long term hazards and storage requirements of the actinide waste elements and their decay daughters. The actinide recycle studies also included plutonium burnup studies in the event that plutonium is no longer required as a fuel. Particular emphasis was placed upon the timing of the recycle program, the requirements for separability of the waste materials, and the impact of the actinides on the reactor operations and performance. It is concluded that actinide recycle and plutonium burnout are attractive alternative waste management concepts. 25 refs., 14 figs., 34 tabs

  6. A calculation for radial expectation values of helium like actinide ions (Z=89-93)

    Ürer, G.; Arslan, M.; Balkaya, E.; Keçeli, A.

    2016-03-01

    Radial expectation values, , for helium like actinides (ZAc=89, ZTh=90, ZPa=91, ZU=92, and ZNp=93) are reported using the Multiconfiguration Hartree-Fock (MCHF) within the framework Breit-Pauli corrections. Atomic data as energy levels, wavelengths, weighted oscillator strengths, and transition probabilities for allowed and forbidden transitions need these calculations. The obtained results are compared available works.

  7. Triaxiality as essential feature for electromagnetic strength, level density and neutron capture cross sections in heavy nuclei

    Reliable predictions for compound nuclear processes leading to nuclides outside the valley of stability are of importance for nuclear astrophysics as well as for the transmutation of nuclear waste. Assuming triaxiality in nearly all nuclei with A>70 a combined parameterization is presented for level density and photon strength. For the strength functions a fit to IVGDR shapes by the sum of three Lorentzians adding up to the TRK sum rule is used. Only two global fit-parameters are needed and a third one suffices to also describe level densities sufficiently well, if the significant collective enhancement due to the loss of axial symmetry is accounted for. Predicted level distances for the small spins reached by capture at the neutron threshold agree well to observations for more than 100 spin-0 target nuclei. Simultaneously derived neutron capture cross sections in the range of unresolved resonances are in accord to experimental findings as well as to Maxwellian averages (kT=30 keV) of neutron capture cross sections compiled recently for simulations of nuclear reactions in AGB-stars.

  8. Correlation of Serum Leptin Level with Bone Mineral Density and Bone Turnover Markers in Chinese Adolescent Dancers

    LI-CHEN YANG; YAN LAN; JING HU; YAN-HUA YANG; QIAN ZHANG; JIAN-HUA PIAO

    2009-01-01

    Objective To investigate plasma leptin concentrations in adolescent female dancers and to determine whether leptin has some effects on their bone mineral density (BMD) and bone turnover markers. Methods Sixty dancers aged 15-17 years and 77 healthy controls were enrolled in the study. Bone mineral density (BMD) and body composition were detected by dual energy X-ray absorptiometry. Serum leptin concentrations were measured by radioimmunoassay (RIA). Two bone turnover markers, bone-specific alkaline phosphatase (BAP) and tartrate-resistant acid phosphatase(TRACP), were determined by ELISA. Results The dancers had a lower fat mass and a lower leptin level than the controls, while they had a relatively higher BMD of the total body and legs after adjustment for BMI and age. The levels of bone resorption and formation of markers were higher in the dancers than in the controls. Leptin was positively correlated with BMI, body weight, fat mass, and percentage of body fat. In dancers, Leptin was positively correlated with the BMD of the total body and the left leg. However, after adjustment for BMI, no correlation of serum leptin concentrations with BMD values was found in either dancers or controls. Nor correlation was found between leptin and bone turnover markers after adjustment for BMI. Conclusion The leptin profile is different between the controls and the dancers with a lower BMI and a lower fat mass. Circulating plasma leptin level depends on BMI and is not a direct determinant of BMD in Chinese adolescent dancers.

  9. Macular pigment optical density and its relationship with serum and dietary levels of lutein and zeaxanthin.

    Beatty, Stephen; Nolan, John; Kavanagh, Heather; O'Donovan, Orla

    2004-10-01

    Observational evidence is accumulating that the onset of age-related maculopathy, the leading cause of legal blindness in the Western World, could be delayed, or even averted, with antioxidant supplements. Lutein (L) and zeaxanthin (Z) are two hydroxy-carotenoids with antioxidant activity which accumulate at the macula, where they are collectively known as macular pigment (MP). It has been shown that MP is entirely of dietary origin, and that L and Z levels in serum, diet, and retina correlate. However, the nature of the relationships between L and Z in foodstuffs, blood, and macula is confounded by many variables including processes which influence digestion, absorption, and transport of the compounds in question, and accumulation and stabilization of the carotenoids in the tissues. If macular pigment is protective for age-related maculopathy, a clear understanding of the mechanisms whereby L and Z arrive at the target tissue (retina) from their source (foodstuff) is essential. In this paper, we review the literature germane to this growing area of interest. PMID:15325913

  10. Detection of the actinides and cesium from environmental samples

    Snow, Mathew Spencer

    Detection of the actinides and cesium in the environment is important for a variety of applications ranging from environmental remediation to safeguards and nuclear forensics. The utilization of multiple different elemental concentrations and isotopic ratios together can significantly improve the ability to attribute contamination to a unique source term and/or generation process; however, the utilization of multiple elemental "signatures" together from environmental samples requires knowledge of the impact of chemical fractionation for various elements under a variety of environmental conditions (including predominantly aqueous versus arid conditions). The research reported in this dissertation focuses on three major areas: 1. Improving the understanding of actinide-mineral interactions at ultra-low concentrations. Chapter 2 reports a batch sorption and modeling study of Np(V) sorption to the mineral goethite from attomolar to micromolar concentrations. 2. Improving the detection capabilities for Thermal Ionization Mass Spectrometry (TIMS) analyses of ultra-trace cesium from environmental samples. Chapter 4 reports a new method which significantly improves the chemical yields, purification, sample processing time, and ultimately, the detection limits for TIMS analyses of femtogram quantities of cesium from a variety of environmental sample matrices. 3. Demonstrating how actinide and cesium concentrations and isotopic ratios from environmental samples can be utilized together to determine a wealth of information including environmental transport mechanisms (e.g. aqueous versus arid transport) and information on the processes which generated the original material. Chapters1, 3 and 5 demonstrate these principles using Pu, Am, Np, and Cs concentrations and isotopic ratios from contaminated soils taken near the Subsurface Disposal Area (SDA) of Idaho National Laboratory (INL) (a low level radioactive waste disposal site in southeastern Idaho).

  11. Treatment of actinide-containing organic waste

    A method has been developed for reducing the volume of organic wastes and recovering the actinide elements. The waste, together with gaseous oxygen (air) is introduced into a molten salt, preferably an alkali metal carbonate such as sodium carbonate. The bath is kept at 7500 - 10000C and 0.5 - 10 atm to thermally decompose and partially oxidize the waste, while substantially reducing its volume. The gaseous effluent, mainly carbon dioxide and water vapour, is vented to the atmosphere through a series of filters to remove trace amounts of actinide elements or particulate alkali metal salts. The remaining combustion products are entrained in the molten salt. Part of the molten salt-combustion product mixture is withdrawn and mixed with an aqueous medium. Insoluble combustion products are then removed from the aqueous medium and are leached with a mixture of hydrofluoric and nitric acids to solubilize the actinide elements. The actinide elements are easily recovered from the acid solution using conventional techniques. (DN)

  12. Actinide measurements by AMS using fluoride matrices

    Cornett, R. J.; Kazi, Z. H.; Zhao, X.-L.; Chartrand, M. G.; Charles, R. J.; Kieser, W. E.

    2015-10-01

    Actinides can be measured by alpha spectroscopy (AS), mass spectroscopy or accelerator mass spectrometry (AMS). We tested a simple method to separate Pu and Am isotopes from the sample matrix using a single extraction chromatography column. The actinides in the column eluent were then measured by AS or AMS using a fluoride target matrix. Pu and Am were coprecipitated with NdF3. The strongest AMS beams of Pu and Am were produced when there was a large excess of fluoride donor atoms in the target and the NdF3 precipitates were diluted about 6-8 fold with PbF2. The measured concentrations of 239,240Pu and 241Am agreed with the concentrations in standards of known activity and with two IAEA certified reference materials. Measurements of 239,240Pu and 241Am made at A.E. Lalonde AMS Laboratory agree, within their statistical uncertainty, with independent measurements made using the IsoTrace AMS system. This work demonstrated that fluoride targets can produce reliable beams of actinide anions and that the measurement of actinides using fluorides agree with published values in certified reference materials.

  13. Trends in actinide processing at Hanford

    In 1989, the mission at the Hanford Site began a dramatic and sometimes painful transition. The days of production--as we used to know it--are over. Our mission officially has become waste management and environmental cleanup. This mission change didn't eliminate many jobs--in fact, budgets have grown dramatically to support the new mission. Most all of the same skilled crafts, engineers, and scientists are still required for the new mission. This change has not eliminated the need for actinide processing, but it has certainly changed the focus that our actinide chemists and process engineers have. The focus used to be on such things as increasing capacity, improving separations efficiency, and product purity. Minimizing waste had become a more important theme in recent years and it is still a very important concept in the waste management and environmental cleanup arena. However, at Hanford, a new set of words dominates the actinide process scene as we work to deal with actinides that still reside in a variety of forms at the Hanford Site. These words are repackage, stabilize, remove, store and dispose. Some key activities in each of these areas are described in this report

  14. Report of the panel on inhaled actinides

    Some topics discussed are as follows: assessment of risks to man of inhaling actinides; use of estimates for developing protection standards; epidemiology of lung cancer in exposed human populations; development of respiratory tract models; and effects in animals: dose- and effect-modifying factors

  15. Electronic Structure of the Actinide Metals

    Johansson, B.; Skriver, Hans Lomholt

    1982-01-01

    itinerant to localized 5f electron behaviour calculated to take place between plutonium and americium. From experimental data it is shown that the screening of deep core-holes is due to 5f electrons for the lighter actinide elements and 6d electrons for the heavier elements. A simplified model for the full...

  16. Actinide and fission product partitioning and transmutation

    The third international information exchange meeting on actinide and fission product partitioning and transmutation, took place in Cadarache France, on 12-14 December 1994. The proceedings are presented in six sessions : an introduction session, the major programmes and international cooperation, the systems studies, the reactors fuels and targets, the chemistry and a last discussions session. (A.L.B.)

  17. Actinide and fission product partitioning and transmutation

    NONE

    1995-07-01

    The third international information exchange meeting on actinide and fission product partitioning and transmutation, took place in Cadarache France, on 12-14 December 1994. The proceedings are presented in six sessions : an introduction session, the major programmes and international cooperation, the systems studies, the reactors fuels and targets, the chemistry and a last discussions session. (A.L.B.)

  18. Rapid determination of actinides in asphalt samples

    A new rapid method for the determination of actinides in asphalt samples has been developed that can be used in emergency response situations or for routine analysis. If a radiological dispersive device, improvised nuclear device or a nuclear accident such as the accident at the Fukushima Nuclear Power Plant in March, 2011 occurs, there will be an urgent need for rapid analyses of many different environmental matrices, including asphalt materials, to support dose mitigation and environmental clean-up. The new method for the determination of actinides in asphalt utilizes a rapid furnace step to destroy bitumen and organics present in the asphalt and sodium hydroxide fusion to digest the remaining sample. Sample preconcentration steps are used to collect the actinides and a new stacked TRU Resin + DGA Resin column method is employed to separate the actinide isotopes in the asphalt samples. The TRU Resin plus DGA Resin separation approach, which allows sequential separation of plutonium, uranium, americium and curium isotopes in asphalt samples, can be applied to soil samples as well. (author)

  19. Placental transfer of plutonium and other actinides

    The report is based on an extensive literature search. All data available from studies on placental transfer of plutonium and other actinides in man and animals have been collected and analysed, and the report presents the significant results as well as unresolved questions and knowledge gaps which may serve as a waypost to future research work. (orig./MG)

  20. ENDF/B-5 Actinides (Rev. 86)

    This document summarizes the contents of the Actinides part of the ENDF/B-5 nuclear data library released by the US National Nuclear Data Center. This library or selective retrievals of it, are available costfree from the IAEA Nuclear Data Section upon request. The present version of the library is the Revision of 1986. (author). Refs, figs and tabs

  1. Spin–orbit coupling in actinide cations

    Bagus, Paul S.; Ilton, Eugene S.; Martin, Richard L.;

    2012-01-01

    The limiting case of Russell–Saunders coupling, which leads to a maximum spin alignment for the open shell electrons, usually explains the properties of high spin ionic crystals with transition metals. For actinide compounds, the spin–orbit splitting is large enough to cause a significantly reduced...

  2. A predictor of atheroma progression in patients achieving very low levels of low-density lipoprotein cholesterol

    Nozue, Tsuyoshi; Yamamoto, Shingo; Tohyama, Shinichi; Fukui, Kazuki; Umezawa, Shigeo; Onishi, Yuko; Kunishima, Tomoyuki; Hibi, Kiyoshi; Terashima, Mitsuyasu; Michishita, Ichiro

    2013-01-01

    An aggressive reduction in low-density lipoprotein cholesterol (LDL-C) with statins produces regression or stabilization of coronary artery plaques. However, after achieving very low levels of LDL-C, atheroma regression is not observed in all patients. The purpose of the present study was to evaluate the determinants of atheroma progression despite achieving very low levels of LDL-C. The effects of 8-month statin therapy on coronary atherosclerosis were evaluated using virtual histology intravascular ultrasound in the TRUTH study. Of these, 33 patients who achieved an on-treatment LDL-C level of <70 mg/dl were divided into 2 groups according to increase in plaque volume (progressors, n= 16) or decrease in plaque volume (regressors, n= 17) during an 8-month follow-up period. At the 8-month follow-up, serum LDL-C and apolipoprotein B levels were significantly lower in progressors than in regressors; however, significant increases in high-density lipoprotein cholesterol and apolipoprotein AI and decreases in high-sensitivity C-reactive protein and oxidized LDL were observed only in regressors. The changes in the n-3 to n-6 polyunsaturated fatty acid ratios significantly differed between the 2 groups. Multivariate regression analysis showed that a decrease in the eicosapentaenoic acid + docosahexaenoic acid/arachidonic acid ratio was a significant predictor associated with atheroma progression (β= -0.512, p= 0.004). In conclusions, n-3 to n-6 polyunsaturated fatty acid ratios affected coronary artery plaque progression and regression in patients who achieved very low levels of LDL-C during statin therapy. PMID:24224137

  3. ACTINET: a European Network for Actinide Sciences

    Full text of publication follows: The research in Actinide sciences appear as a strategic issue for the future of nuclear systems. Sustainability issues are clearly in connection with the way actinide elements are managed (either addressing saving natural resource, or decreasing the radiotoxicity of the waste). The recent developments in the field of minor actinide P and T offer convincing indications of what could be possible options, possible future processes for the selective recovery of minor actinides. But they point out, too, some lacks in the basic understanding of key-issues (such as for instance the control An versus Ln selectivity, or solvation phenomena in organic phases). Such lacks could be real obstacles for an optimization of future processes, with new fuel compounds and facing new recycling strategies. This is why a large and sustainable work appears necessary, here in the field of basic actinide separative chemistry. And similar examples could be taken from other aspects of An science, for various applications (nuclear fuel or transmutation targets design, or migration issues,): future developments need a strong, enlarged, scientific basis. The Network ACTINET, established with the support of the European Commission, has the following objectives: - significantly improve the accessibility of the major actinide facilities to the European scientific community, and form a set of pooled facilities, as the corner-stone of a progressive integration process, - improve mobility between the member organisations, in particular between Academic Institutions and National Laboratories holding the pooled facilities, - merge part of the research programs conducted by the member institutions, and optimise the research programs and infrastructure policy via joint management procedures, - strengthen European excellence through a selection process of joint proposals, and reduce the fragmentation of the community by putting critical mass of resources and expertise on

  4. Evaluation of Interspecific Interaction Between Encarsia lutea and Eretomocerus near mundus, the Parasitoids of Cotton Whitefly (Bemisia tabaci) with Host Plants Density Levels and Preference

    Arshad Ullah, Muhammad; Abbasi, Khalida Hamid; Bano, Saadia; Khanum, Saeeda

    `Studies were carried out at CABI Biosciences Pakistan Centre, Rawalpindi to evaluate the effects of host plants and insects with host density levels and preference by both these species, i.e., Encarsia lutea and Eretomocerus separately as well as together in competitive situation. Preference of density levels by both parasitoids species showed that density level 20 (cotton leaf disc with 20 Bemisia tabaci nymphs and pupae) was contributed more (42%) preference than other density levels (5, 10, 40, 60 and 80). Different density levels had highly significant effect on settlement time of both species separately while in competitive situation the settlement time of both species was not significantly different from each other on different treatments.

  5. RELATIVISTIC EFFECTS ON THE EQUATION OF STATE OF THE LIGHT ACTINIDES

    Landa, A; Soderlind, P

    2005-11-04

    The effect of the relativistic spin-orbit (SO) interaction on the bonding in the early actinides has been investigated by means of electronic-structure calculations. Specifically, the equation of state (EOS) for the face-centered cubic (fcc) model systems of these metals have been calculated from the first-principles density-functional theory (DFT). Traditionally, the SO interaction in electronic-structure methods is implemented as a perturbation to the Hamiltonian that is solved for basis functions that explicitly do not depend on SO coupling. Here this approximation is shown to compare well with the fully relativistic Dirac treatment. It is further shown that SO coupling has a gradually increasing effect on the EOS as one proceeds through the actinides and the effect is diminished as density increases.

  6. Accumulation of Oxidized Low-Density Lipoprotein in Psoriatic Skin and Changes of Plasma Lipid Levels in Psoriatic Patients

    Nilgun Solak Tekin

    2007-01-01

    Full Text Available Background. Psoriasis is a chronic inflammatory skin disease characterized by an accelerated turnover of epidermal cells and an incomplete differentiation in epidermis with lesion. However, the exact etiology of psoriasis is unknown. Abnormalities in essential fatty acid metabolism, free radical generation, lipid peroxidation, and release of lymphokines have been proposed. Objective. Our purpose was to evaluate the plasma lipids and oxidized low-density lipoprotein accumulation in psoriatic skin lesion in order to ascertain the possible participation of oxidative stress and oxidative modification of lipids in pathogenesis of psoriasis. Methods. The study group included 84 patients with psoriasis, and 40 sex- and age-matched healthy volunteers. Blood lipid profile was determined. Psoriatic and nonlesional skin samples of psoriatic patients were evaluated for the presence of oxidized low-density lipoprotein by using an immune-fluorescent staining method. Results. The mean levels of lipids (total cholesterol, triglyceride, and LDL cholesterol in patients with psoriasis were found to be significantly higher than those of healthy subjects. Psoriatic skins were shown positive oxidized low-density lipoprotein staining. There was no staining in nonlesional skin samples of the same individuals. Conclusion. Lipid peroxidation mediated by free radicals is believed to be one of the important causes of cell membrane destruction and cell damage. This study shows for the first time the accumulation of oxidized low-density lipoprotein in psoriatic skin lesion. We believe that accumulation of ox-LDL in psoriatic skin may have an important role in the immune-inflammatory events that result in progressive skin damage.

  7. Road density

    U.S. Environmental Protection Agency — Road density is generally highly correlated with amount of developed land cover. High road densities usually indicate high levels of ecological disturbance. More...

  8. A comparison of nitrate level in spinach grown both under different densities in aquaponic system and under natural growth conditions

    Ştefan Mihai PETREA

    2013-12-01

    Full Text Available As bio-integrated systems that link both plants and fish culture, inside aquaponic systems, the processes of ammonia-oxidizing and nitrification in nitrite and nitrate are essential for growth and development of both fish and plants culture biomass. Plants with nearly the same nutritional requirements during their life cycle, like spinach in our case, are recommended to be grown under aquaponic conditions. Although nitrates concentrations up to 200 – 250mg/l are reported to be acceptable for fish growth, in the last years the toxic effect of long term exposure to high nitrate levels on fish and plants cultured biomass were highlighted. The main goal of the present study is to compare the nitrate level of spinach, grown in an aquaponic system, under three plant densities (V1 - 59 plants/m2, V2 - 48plants/m2 and V3 – 39 plants/m2. The second objective is to compare the results obtained, in term of nitrate content, for spinach grown in the integrated rainbow trout – spinach aquaponic system with those of marketable spinach, grown under conventional condition, in the field. The experimental design consists in a recirculating aquaculture system with 12 growing units, mechanical and biological water treatment units and four aquaponic units. Fish were fed with two types of feed with 41% and 50% protein, using 3 different feeding regimes. The results show a higher nitrate level on spinach grown in aquaponic system, compared to the one derived from field culture. Differences were observed also among the three variants grown in aquaponic conditions, under different plant densities. As a conclusion, it can be said that considering the nitrate level, spinach grown in aquaponic system is marketable.

  9. Metal ionophore treatment restores dendritic spine density and synaptic protein levels in a mouse model of Alzheimer's disease.

    Paul A Adlard

    Full Text Available We have previously demonstrated that brief treatment of APP transgenic mice with metal ionophores (PBT2, Prana Biotechnology rapidly and markedly improves learning and memory. To understand the potential mechanisms of action underlying this phenomenon we examined hippocampal dendritic spine density, and the levels of key proteins involved in learning and memory, in young (4 months and old (14 months female Tg2576 mice following brief (11 days oral treatment with PBT2 (30 mg/kg/d. Transgenic mice exhibited deficits in spine density compared to littermate controls that were significantly rescued by PBT2 treatment in both the young (+17%, p<0.001 and old (+32%, p<0.001 animals. There was no effect of PBT2 on spine density in the control animals. In the transgenic animals, PBT2 treatment also resulted in significant increases in brain levels of CamKII (+57%, p = 0.005, spinophilin (+37%, p = 0.04, NMDAR1A (+126%, p = 0.02, NMDAR2A (+70%, p = 0.05, pro-BDNF (+19%, p = 0.02 and BDNF (+19%, p = 0.04. While PBT2-treatment did not significantly alter neurite-length in vivo, it did increase neurite outgrowth (+200%, p = 0.006 in cultured cells, and this was abolished by co-incubation with the transition metal chelator, diamsar. These data suggest that PBT2 may affect multiple aspects of snaptic health/efficacy. In Alzheimer's disease therefore, PBT2 may restore the uptake of physiological metal ions trapped within extracellular β-amyloid aggregates that then induce biochemical and anatomical changes to improve cognitive function.

  10. A predictor of atheroma progression in patients achieving very low levels of low-density lipoprotein cholesterol.

    Nozue, Tsuyoshi; Yamamoto, Shingo; Tohyama, Shinichi; Fukui, Kazuki; Umezawa, Shigeo; Onishi, Yuko; Kunishima, Tomoyuki; Hibi, Kiyoshi; Terashima, Mitsuyasu; Michishita, Ichiro

    2013-01-01

    An aggressive reduction in low-density lipoprotein cholesterol (LDL-C) with statins produces regression or stabilization of coronary artery plaques. However, after achieving very low levels of LDL-C, atheroma regression is not observed in all patients. The purpose of the present study was to evaluate the determinants of atheroma progression despite achieving very low levels of LDL-C. The effects of 8-month statin therapy on coronary atherosclerosis were evaluated using virtual histology intravascular ultrasound in the TRUTH study. Of these, 33 patients who achieved an on-treatment LDL-C level of cholesterol and apolipoprotein AI and decreases in high-sensitivity C-reactive protein and oxidized LDL were observed only in regressors. The changes in the n-3 to n-6 polyunsaturated fatty acid ratios significantly differed between the 2 groups. Multivariate regression analysis showed that a decrease in the eicosapentaenoic acid + docosahexaenoic acid/arachidonic acid ratio was a significant predictor associated with atheroma progression (β= -0.512, p= 0.004). In conclusions, n-3 to n-6 polyunsaturated fatty acid ratios affected coronary artery plaque progression and regression in patients who achieved very low levels of LDL-C during statin therapy. PMID:24224137

  11. Systematic review of green tea epigallocatechin gallate in reducing low-density lipoprotein cholesterol levels of humans.

    Momose, Yuko; Maeda-Yamamoto, Mari; Nabetani, Hiroshi

    2016-09-01

    We conducted a systematic review of the literature for the ability of green tea epigallocatechin gallate (EGCG) to lower low-density lipoprotein cholesterol (LDL-C). Study subjects were limited to healthy individuals and randomized, controlled trials on human serum lipid levels, especially LDL-C, conducted. A total of 17 trials (n = 1356) met all of the inclusion criteria. According to weighted mean differences for changes from baseline with 95% confidence intervals (CI), 107-856 mg/d of EGCG for 4 to 14 weeks reduced LDL-C by -9.29 mg/dl (95% CI, -12.27 to -6.31). Sub-analysis was performed to compare the EGCG lowering effect on LDL-C between non-obese and obese subjects, EGCG dose, baseline of LDL-C levels, or BMI. We concluded that consumption of green tea EGCG resulted in a significant reduction of LDL-C at any baseline level and any dose between 107 and 856 mg/d, and the effect size was slightly dependent on the baseline lipid level of the subjects. PMID:27324590

  12. Energy level alignment and quantum conductance of functionalized metal-molecule junctions: Density functional theory versus GW calculations

    We study the effect of functional groups (CH3*4, OCH3, CH3, Cl, CN, F*4) on the electronic transport properties of 1,4-benzenediamine molecular junctions using the non-equilibrium Green function method. Exchange and correlation effects are included at various levels of theory, namely density functional theory (DFT), energy level-corrected DFT (DFT+Σ), Hartree-Fock and the many-body GW approximation. All methods reproduce the expected trends for the energy of the frontier orbitals according to the electron donating or withdrawing character of the substituent group. However, only the GW method predicts the correct ordering of the conductance amongst the molecules. The absolute GW (DFT) conductance is within a factor of two (three) of the experimental values. Correcting the DFT orbital energies by a simple physically motivated scissors operator, Σ, can bring the DFT conductances close to experiments, but does not improve on the relative ordering. We ascribe this to a too strong pinning of the molecular energy levels to the metal Fermi level by DFT which suppresses the variation in orbital energy with functional group

  13. Energy level alignment and quantum conductance of functionalized metal-molecule junctions: Density functional theory versus GW calculations

    Jin, Chengjun; Markussen, Troels; Thygesen, Kristian S., E-mail: thygesen@fysik.dtu.dk [Center for Atomic-scale Materials Design, Department of Physics, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark); Strange, Mikkel; Solomon, Gemma C. [Nano-Science Center and Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen Ø (Denmark)

    2013-11-14

    We study the effect of functional groups (CH{sub 3}*4, OCH{sub 3}, CH{sub 3}, Cl, CN, F*4) on the electronic transport properties of 1,4-benzenediamine molecular junctions using the non-equilibrium Green function method. Exchange and correlation effects are included at various levels of theory, namely density functional theory (DFT), energy level-corrected DFT (DFT+Σ), Hartree-Fock and the many-body GW approximation. All methods reproduce the expected trends for the energy of the frontier orbitals according to the electron donating or withdrawing character of the substituent group. However, only the GW method predicts the correct ordering of the conductance amongst the molecules. The absolute GW (DFT) conductance is within a factor of two (three) of the experimental values. Correcting the DFT orbital energies by a simple physically motivated scissors operator, Σ, can bring the DFT conductances close to experiments, but does not improve on the relative ordering. We ascribe this to a too strong pinning of the molecular energy levels to the metal Fermi level by DFT which suppresses the variation in orbital energy with functional group.

  14. Numerical analysis on reduction of radioactive actinides by recycling of nuclear fuel

    Worldwide, human growth has reached unparalleled levels historically, this implies a need for more energy, and just in 2007 was consumed in the USA 4157 x 109 kWh of electricity and there were 6 x 109 metric tons of carbon dioxide, which causes a devastating effect on our environment. To this problem, a solution to the demand for non-fossil energy is nuclear energy, which is one of the least polluting and the cheapest among non-fossil energy; however, a problem remains unresolved the waste generation of nuclear fuels. In this work the option of a possible transmutation of actinides in a nuclear reactor of BWR was analyzed, an example of this are the nuclear reactors at the Laguna Verde nuclear power plant, which have generated spent fuel stored in pools awaiting a decision for final disposal or any other existing alternative. Assuming that the spent fuel was reprocessed to separate useful materials and actinides such as plutonium and uranium remaining, could take these actinides and to recycle them inside the same reactor that produced them, so il will be reduced the radiotoxicity of spent fuel. The main idea of this paper is to evaluate by means of numeric simulation (using the Core Management System (CMS)) the reduction of minor actinides in the case of being recycled in fresh fuel of the type BWR. The actinides were introduced hypothetically in the fuel pellets to 6% by weight, and then use a burned in the range of 0-65 G Wd/Tm, in order to have a better panorama of their behavior and thus know which it is the best choice for maximum reduction of actinides. Several cases were studied, that is to say were used as fuels; the UO2 and MOX. Six different cases were also studied to see the behavior of actinides in different situations. The CMS platform calculation was used for the analysis of the cases presented. Favorable results were obtained, having decreased from a range of 35% to 65% of minor actinides initially introduced in the fuel rods, reducing the

  15. Low density lipoprotein cholesterol level inversely correlated with coronary flow velocity reserve in patients with Type 2 diabetes

    Jie Yu; Jiang-Li Han; Li-Yun He; Xin-Heng Feng; Wei-Hong Li; Jie-Ming Mao; Wei Gao; Guang Wang

    2013-01-01

    Objectives To evaluate the association of coronary artery endothelial function and plasma levels of low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) in patients with Type 2 Diabetes Mellitus (DM). Methods We investigated 90 participants from our institution between October 2007 to March 2010: non-DM (n = 60) and DM (n = 30). As an indicator of coronary endothelial dysfunction, we used non-invasive Doppler echocardiography to quantify coronary flow velocity reserve (CFVR) in the distal part of the left descending artery after rest and after intravenous adenosine administration. Results Plasma level of LDL-C was significantly higher in patients with DM than in non-DM (3.21 0.64 vs. 2.86 0.72 mmo/L, P < 0.05), but HDL-C level did not differ between the groups (1.01 0.17 vs. 1.05 0.19 mmo/L). Furthermore, the CFVR value was lower in DM patients than non-diabetics (2.45±0.62 vs. 2.98±0.68, P < 0.001). Plasma levels of LDL-C were negatively correlated with CFVR in all subjects (r = 0.35, P < 0.001; 95% confidence interval (CI): 0.52 -C0.15) and in the non-DM (r = 0.29, P < 0.05; 95% CI: 0.51–0.05), with an even stronger negative correlation in the DM group (r = 0.42, P < 0.05; 95% CI: 0.68 –0.06). Age (β = 0.019, s = 0.007, sβ = 0.435, 95% CI: 0.033 –0.005, P = 0.008), LDL-C (β = 0.217, s = 0.105, sβ = 0.282, 95% CI: 0.428 –0.005, P = 0.045) remained independently correlated with CFVR in the DM group. However, we found no correlation between HDL-C level and CFVR in any group. Conclusions Diabetes may contribute to coronary artery disease (CAD) by inducing dysfunction of the coronary artery endothelium. Increased LDL-C level may adversely impair coronary endothelial function in DM. HDL-C may lose its endothelial-protective effects, in part as a result of pathological conditions, especially under abnormal glucose metabolism.

  16. Synthesis of actinide nitrides, phosphides, sulfides and oxides

    Van Der Sluys, William G.; Burns, Carol J.; Smith, David C.

    1992-01-01

    A process of preparing an actinide compound of the formula An.sub.x Z.sub.y wherein An is an actinide metal atom selected from the group consisting of thorium, uranium, plutonium, neptunium, and americium, x is selected from the group consisting of one, two or three, Z is a main group element atom selected from the group consisting of nitrogen, phosphorus, oxygen and sulfur and y is selected from the group consisting of one, two, three or four, by admixing an actinide organometallic precursor wherein said actinide is selected from the group consisting of thorium, uranium, plutonium, neptunium, and americium, a suitable solvent and a protic Lewis base selected from the group consisting of ammonia, phosphine, hydrogen sulfide and water, at temperatures and for time sufficient to form an intermediate actinide complex, heating said intermediate actinide complex at temperatures and for time sufficient to form the actinide compound, and a process of depositing a thin film of such an actinide compound, e.g., uranium mononitride, by subliming an actinide organometallic precursor, e.g., a uranium amide precursor, in the presence of an effectgive amount of a protic Lewis base, e.g., ammonia, within a reactor at temperatures and for time sufficient to form a thin film of the actinide compound, are disclosed.

  17. Adventures in Actinide Chemistry: A Year of Exploring Uranium and Thorium in Los Alamos

    Pagano, Justin [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-01-08

    The first part of this collection of slides is concerned with considerations when working with actinides. The topics discussed in the document as a whole are the following: Actinide chemistry vs. transition metal chemistry--tools we can use; New synthetic methods to obtain actinide hydrides; Actinide metallacycles: synthesis, structure, and properties; and Reactivity of actinide metallacycles.

  18. Adventures in Actinide Chemistry: A Year of Exploring Uranium and Thorium in Los Alamos

    The first part of this collection of slides is concerned with considerations when working with actinides. The topics discussed in the document as a whole are the following: Actinide chemistry vs. transition metal chemistry--tools we can use; New synthetic methods to obtain actinide hydrides; Actinide metallacycles: synthesis, structure, and properties; and Reactivity of actinide metallacycles.

  19. Effects of actinide burning on waste disposal at Yucca Mountain

    Release rates of 15 radionuclides from waste packages expected to result from partitioning and transmutation of Light-Water Reactor (LWR) and Actinide-Burning Liquid-Metal Reactor (ALMR) spent fuel are calculated and compared to release rates from standard LWR spent fuel packages. The release rates are input to a model for radionuclide transport from the proposed geologic repository at Yucca Mountain to the water table. Discharge rates at the water table are calculated and used in a model for transport to the accessible environment, defined to be five kilometers from the repository edge. Concentrations and dose rates at the accessible environment from spent fuel and wastes from reprocessing, with partitioning and transmutation, are calculated. Partitioning and transmutation of LWR and ALMR spent fuel reduces the inventories of uranium, neptunium, plutonium, americium and curium in the high-level waste by factors of 40 to 500. However, because release rates of all of the actinides except curium are limited by solubility and are independent of package inventory, they are not reduced correspondingly. Only for curium is the repository release rate much lower for reprocessing wastes

  20. Hollow fibre supported liquid membrane based separations of actinides

    Renaissance in nuclear energy is poised to make a significant contribution to the diversification of clean energy resources and to reduce the burden of CO2 in atmosphere. Its sustainability lies in using nature's mineral resources in an efficient and environmentally friendly way. One of the major challenges in the nuclear energy programme has, however, been the management of radioactive waste in a manner which allays apprehensions about its adverse impact on the environment. Innovative approaches are being devised internationally to treat spent nuclear fuel as a source of valuables. Separation of long-lived radionuclides such as actinides and fission products from high level radioactive waste is a challenging task for the chemists working on the reprocessing and waste management processes involved at the tail end of nuclear fuel cycle. Amongst the various separation techniques, liquid membrane based separation methods are becoming increasingly popular due to factors such as ligand economy, high efficiency and low power consumption. Techniques such as emulsion liquid membrane and hollow fibre based non-dispersive solvent extraction methods are reported to be more efficient than the solvent extraction based separation methods which have limitations of emulsion/third phase or crud formation. In the present article, an attempt has been made to review the work carried out internationally as well as in the author's laboratory on liquid membrane based actinides separations during last few years with a particular focus on the use of hollow fibre supported liquid membranes. (author)