Actinides(3)/lanthanides(3) separation by nano-filtration assisted by complexation; Separation actinides(3)lanthanides(3) par nanofiltration assistee par complexation

Energy Technology Data Exchange (ETDEWEB)

Sorin, A

2006-07-01

In France, one of the research trend concerning the reprocessing of spent nuclear fuel consists to separate selectively the very radio-toxic elements with a long life to be recycled (Pu) or transmuted (Am, Cm, Np). The aim of this thesis concerns the last theme about actinides(III)/lanthanides(III) separation by a process of nano-filtration assisted by complexation. Thus, a pilot of tangential membrane filtration was designed and established in a glove box at the ATALANTE place of CEA-Marcoule. Physico-chemical characterisation of the Desal GH membrane (OSMONICS), selected to carry out actinides(III)/lanthanides(III) separation, was realized to determine the zeta potential of the active layer and its resistance to ionizing radiations. Moreover, a parametric study was also carried out to optimize the selectivity of complexation, and the operating conditions of complex retention (influences of the transmembrane pressure, solute concentration, tangential velocity and temperature). Finally, the separation of traces of Am(III) contained in a mixture of lanthanides(III), simulating the real load coming from a reprocessing cycle, was evaluated with several chelating agents such as poly-amino-carboxylic acids according to the solution acidity and the [Ligand]/[Cation(III)] ratio. (author)

Factors influencing the transport of actinides in the groundwater environment. Final report

International Nuclear Information System (INIS)

Sheppard, J.C.; Kittrick, J.A.

1983-01-01

This report summarizes investigations of factors that significantly influence the transport of actinide cations in the groundwater environment. Briefly, measurements of diffusion coefficients for Am(III), Cm(III), and Np(V) in moist US soils indicated that diffusion is negligible compared to mass transport in flowing groundwater. Diffusion coefficients do, however, indicate that, in the absence of flowing water, actinide elements will migrate only a few centimeters in a thousand years. The remaining investigations were devoted to the determination of distribution ratios (K/sub d/s) for representative US soils, factors influencing them, and chemical and physical processes related to transport of actinides in groundwaters. The computer code GARD was modified to include complex formation to test the importance of humic acid complexing on the rate of transport of actinides in groundwaters. Use of the formation constant and a range of humic acid, even at rather low concentrations of 10 -5 to 10 -6 molar, significantly increases the actinide transport rate in a flowing aquifer. These computer calculations show that any strong complexing agent will have a similar effect on actinide transport in the groundwater environment. 32 references, 9 figures

Remarkably High Stability of Late Actinide Dioxide Cations: Extending Chemistry to Pentavalent Berkelium and Californium.

Science.gov (United States)

Dau, Phuong D; Vasiliu, Monica; Peterson, Kirk A; Dixon, David A; Gibson, John K

2017-12-06

Actinyl chemistry is extended beyond Cm to BkO 2 + and CfO 2 + through transfer of an O atom from NO 2 to BkO + or CfO + , establishing a surprisingly high lower limit of 73 kcal mol -1 for the dissociation energies, D[O-(BkO + )] and D[O-(CfO + )]. CCSD(T) computations are in accord with the observed reactions, and characterize the newly observed dioxide ions as linear pentavalent actinyls; these being the first Bk and Cf species with oxidation states above IV. Computations of actinide dioxide cations AnO 2 + for An=Pa to Lr reveal an unexpected minimum for D[O-(CmO + )]. For CmO 2 + , and AnO 2 + beyond EsO 2 + , the most stable structure has side-on bonded η 2 -(O 2 ), as An III peroxides for An=Cm and Lr, and as An II superoxides for An=Fm, Md, and No. It is predicted that the most stable structure of EsO 2 + is linear [O=Es V =O] + , einsteinyl, and that FmO 2 + and MdO 2 + , like CmO 2 + , also have actinyl(V) structures as local energy minima. The results expand actinide oxidation state chemistry, the realm of the distinctive actinyl moiety, and the non-periodic character towards the end of the periodic table. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Kinetic of liquid-liquid extraction for uranyl nitrate and actinides (III) and lanthanides (III) nitrates by amide extractants; Cinetique d`extraction liquide-liquide du nitrate d`uranyle et des nitrates d`actinides (III) et de lanthanides (III) par des extractants a fonction amide

Energy Technology Data Exchange (ETDEWEB)

Toulemonde, V [CEA Centre d` Etudes Nucleaires de Saclay, 91 -Gif-sur-Yvette (France); [CEA Centre d` Etudes de la Vallee du Rhone, 30 -Marcoule (France). Dept. d` Exploitation du Retraitement et de Demantelement

1995-12-20

The kinetics of liquid-liquid extraction by amide extractants have been investigated for uranyl nitrate (monoamide extractants), actinides (III) and lanthanides (III) nitrates (diamide extractants). The transfer of the metallic species from the aqueous phase to the organic phase was studied using two experimental devices: ARMOLLEX (Argonne Modified Lewis cell for Liquid Liquid Extraction) and RSC (Rotating Stabilized Cell). The main conclusions are: for the extraction of uranyl nitrate by DEHDMBA monoamide, the rate-controlling step is the complexation of the species at the interface of the two liquids. Thus, an absorption-desorption (according to Langmuir theory) reaction mechanism was proposed; for the extraction of actinides (III) and lanthanides (III) nitrates in nitric acid media by DMDBTDMA diamide, the kinetic is also limited by interfacial reactions. The behavior of Americium and Europium is very similar as fare as their reaction kinetics are concerned. (author). 89 refs.

Complexation of f elements by tripodal ligands containing aromatic nitrogens. Application to the selective extraction of actinides(III)

International Nuclear Information System (INIS)

Wietzke, Raphael

1999-01-01

This work initiates a research project, whose aim is the actinides(lll)/lanthanides(III) separation by liquid-liquid extraction. We were interested in the study of the coordination chemistry of lanthanides(III) and uranium(III) (uranium(III) as model for the actinides(III)), with the aim to show differences between the two families and to better understand the coordination properties involved in the extraction process. We studied the lanthanide(III) and uranium(III) complexation with tripodal ligands containing aromatic nitrogens. Several tripodal ligands were synthesized varying the type and the number of the donor atoms. The lanthanide(III) complexes have been characterized in the solid state and in solution (by several techniques: "1H NMR, ESMS, luminescence, UV spectrophotometry, conductometry). Differences in the coordination were found depending on the nature of the donor atoms. The new ligands, tris(2-pyrazinylmethyl)amine (tpza) et tris(N,N-diethyl-2-carbamoyl-6- pyridylmethyl)amine (tpaa), have shown a selectivity for the actinides(III) with promising results in liquid-liquid extraction. The comparison between the lanthanum(III) and uranium(III) complexes with the ligand tpza showed differences in the bonding nature, which could be attributed to a covalent contribution to the metal-ligand bond. (author) [fr

Gas-Phase Energetics of Actinide Oxides: An Assessment of Neutral and Cationic Monoxides and Dioxides from Thorium to Curium

Science.gov (United States)

Marçalo, Joaquim; Gibson, John K.

2009-09-01

An assessment of the gas-phase energetics of neutral and singly and doubly charged cationic actinide monoxides and dioxides of thorium, protactinium, uranium, neptunium, plutonium, americium, and curium is presented. A consistent set of metal-oxygen bond dissociation enthalpies, ionization energies, and enthalpies of formation, including new or revised values, is proposed, mainly based on recent experimental data and on correlations with the electronic energetics of the atoms or cations and with condensed-phase thermochemistry.

Multiscale structural characterizations of mixed U(iv)-An(iii) oxalates (An(iii) = Pu or Am) combining XAS and XRD measurements.

Science.gov (United States)

Arab-Chapelet, B; Martin, P M; Costenoble, S; Delahaye, T; Scheinost, A C; Grandjean, S; Abraham, F

2016-04-28

Mixed actinide(III,IV) oxalates of the general formula M2.2UAn(C2O4)5·nH2O (An = Pu or Am and M = H3O(+) and N2H5(+)) have been quantitatively precipitated by oxalic precipitation in nitric acid medium (yield >99%). Thorough multiscale structural characterization using XRD and XAS measurements confirmed the existence of mixed actinide oxalate solid solutions. The XANES analysis confirmed that the oxidation states of the metallic cations, tetravalent for uranium and trivalent for plutonium and americium, are maintained during the precipitation step. EXAFS measurements show that the local environments around U(+IV), Pu(+III) and Am(+III) are comparable, and the actinides are surrounded by ten oxygen atoms from five bidentate oxalate anions. The mean metal-oxygen distances obtained by XAS measurements are in agreement with those calculated from XRD lattice parameters.

Spin–orbit coupling in actinide cations

DEFF Research Database (Denmark)

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...... 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....

Development and demonstration of a new SANEX Partitioning Process for selective actinide(III)/lanthanide(III) separation using a mixture of CyMe{sub 4}BTBP and TODGA

Energy Technology Data Exchange (ETDEWEB)

Modolo, G.; Wilden, A.; Daniels, H. [Forschungszentrum Juelich GmbH (Germany). Institute for Energy and Climate Research, IEK-6, Nuclear Waste Management and Reactor Safety; Geist, A.; Magnusson, D. [Karlsruher Institut fuer Technologie, Karlsruhe (Germany). Inst. fuer Nukleare Entsorgung; Malmbeck, R. [European Commission, JRC, Karlsruhe (Germany). Inst. for Transuranium Elements (ITU)

2013-05-01

Within the framework of the European collaborative project ACSEPT, a new SANEX partitioning process was developed at Forschungszentrum Juelich for the separation of the trivalent minor actinides americium, curium and californium from lanthanide fission products in spent nuclear fuels. The development is based on batch solvent extraction studies, single-centrifugal contactor tests and on flow-sheet design by computer code calculations. The used solvent is composed of 6,6{sup '}-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydrobenzo-[1,2-4]trizazin-3-yl)-[2,2{sup '}]-bipyridine (CyMe{sub 4}BTBP) and N,N,N{sup '},N{sup '}-tetraoctyldiglycolamide (TODGA) dissolved in n-octanol. A spiked continuous counter-current test was carried out in miniature centrifugal contactors with the aid of a 20-stage flow-sheet consisting of 12 extraction, 4 scrubbing and 4 stripping stages. A product fraction containing more than 99.9% of the trivalent actinides Am(III), Cm(III) and Cf(III) was obtained. High product/feed decontamination factors >1000 were achieved for these actinides. The trivalent lanthanides were directed to the raffinate of the process with the actinide (III) product stream being contaminated with less than 0.5 mass-% in the initial lanthanides. (orig.)

Advanced Aqueous Separation Systems for Actinide Partitioning

Energy Technology Data Exchange (ETDEWEB)

Nash, Ken [Washington State Univ., Pullman, WA (United States); Martin, Leigh [Idaho National Lab. (INL), Idaho Falls, ID (United States); Lumetta, Gregg [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2015-04-02

One of the most challenging aspects of advanced processing of used nuclear fuel is the separation of transplutonium actinides from fission product lanthanides. This separation is essential if actinide transmutation options are to be pursued in advanced fuel cycles, as lanthanides compete with actinides for neutrons in both thermal and fast reactors, thus limiting efficiency. The separation is difficult because the chemistry of Am3+ and Cm3+ is nearly identical to that of the trivalent lanthanides (Ln3+). The prior literature teaches that two approaches offer the greatest probability of devising a successful group separation process based on aqueous processes: 1) the application of complexing agents containing ligand donor atoms that are softer than oxygen (N, S, Cl-) or 2) changing the oxidation state of Am to the IV, V, or VI state to increase the essential differences between Am and lanthanide chemistry (an approach utilized in the PUREX process to selectively remove Pu4+ and UO22+ from fission products). The latter approach offers the additional benefit of enabling a separation of Am from Cm, as Cm(III) is resistant to oxidation and so can easily be made to follow the lanthanides. The fundamental limitations of these approaches are that 1) the soft(er) donor atoms that interact more strongly with actinide cations than lanthanides form substantially weaker bonds than oxygen atoms, thus necessitating modification of extraction conditions for adequate phase transfer efficiency, 2) soft donor reagents have been seen to suffer slow phase transfer kinetics and hydro-/radiolytic stability limitations and 3) the upper oxidation states of Am are all moderately strong oxidants, hence of only transient stability in media representative of conventional aqueous separations systems. There are examples in the literature of both approaches having been described. However, it is not clear at present that any extant process is sufficiently robust for application at the scale

TUCS/phosphate mineralization of actinides

Energy Technology Data Exchange (ETDEWEB)

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.

Actinide-Aluminate Speciation in Alkaline Radioactive Waste

International Nuclear Information System (INIS)

Clark, David L.; Fedosseev, Alexander M.

2001-01-01

Investigation of behavior of actinides in alkaline media containing AL(III) showed that no aluminate complexes of actinides in oxidation states (IIII-VIII) were formed in alkaline solutions. At alkaline precipitation IPH (10-14) of actinides in presence of AL(III) formation of aluminate compounds is not observed. However, in precipitates contained actinides (IIV)<(VI), and to a lesser degree actinides (III), some interference of components takes place that is reflected in change of solid phase properties in comparison with pure components or their mechanical mixture. The interference decreases with rise of precipitation PH and at PH 14 is exhibited very feebly. In the case of NP(VII) the individual compound with AL(III) is obtained, however it is not aluminate of neptunium(VII), but neptunate of aluminium(III) similar to neptunates of other metals obtained earlier

Study of the selectivity of poly-nitrogenous extracting molecules in the complexation of actinides (III) and lanthanides (III) in solution in anhydrous pyridine; Etude de la selectivite de molecules extractantes polyazotees dans la complexation des actinides (III) et des lanthanides (III) en solution dans la pyridine anhydre

Energy Technology Data Exchange (ETDEWEB)

Riviere, Ch

2000-10-05

The aim of this work is to better understand the factors which contribute to the separation of lanthanides(III) and actinides(III). Polydentate nitrogenous molecules present an interesting selectivity. A thermodynamic study of the complexation in pyridine of lanthanide and uranium by the bipyridine ligand (bipy) has been carried out. The formation constants and the thermodynamic values of the different complexes have been determined. It has been shown that the bipy complexes formation is controlled by the enthalpy and unfavored by the entropy. The conductometry has revealed too a significant difference in the uranium and lanthanides complexation by the bipyridine ligand. The use of the phenanthroline ligand induces a better complexation of the metallic ions but the selectivity is not improved. On the other hand, the decrease of the basicity and the increase of the ligand denticity (for instance in the case of the use of ter-pyridine) favour the selectivity without improving the complexation. The selectivity difference for the complexation of actinides(III) and lanthanides(III) by the different studied ligands (independent systems) has been confirmed by experiments of inter-metals competition. (O.M.)

Structural Characterization of Am(III)- and Pu(III)-DOTA Complexes.

Science.gov (United States)

Audras, Matthieu; Berthon, Laurence; Berthon, Claude; Guillaumont, Dominique; Dumas, Thomas; Illy, Marie-Claire; Martin, Nicolas; Zilbermann, Israel; Moiseev, Yulia; Ben-Eliyahu, Yeshayahu; Bettelheim, Armand; Cammelli, Sebastiano; Hennig, Christoph; Moisy, Philippe

2017-10-16

The complexation of 1,4,7,10-tetrazacyclodecane-1,4,7,10-tetraacetic acid (DOTA) ligand with two trivalent actinides (Am 3+ and Pu 3+ ) was investigated by UV-visible spectrophotometry, NMR spectroscopy, and extended X-ray absorption fine structure in conjunction with computational methods. The complexation process of these two cations is similar to what has been previously observed with lanthanides(III) of similar ionic radius. The complexation takes place in different steps and ends with the formation of a (1:1) complex [(An(III)DOTA)(H 2 O)] - , where the cation is bonded to the nitrogen atoms of the ring, the four carboxylate arms, and a water molecule to complete the coordination sphere. The formation of An(III)-DOTA complexes is faster than the Ln(III)-DOTA systems of equivalent ionic radius. Furthermore, it is found that An-N distances are slightly shorter than Ln-N distances. Theoretical calculations showed that the slightly higher affinity of DOTA toward Am over Nd is correlated with slightly enhanced ligand-to-metal charge donation arising from oxygen and nitrogen atoms.

Extraction characteristics of trivalent lanthanides and actinides in mixtures of dinonylnaphthalenesulfonic acid and carboxylic acids

International Nuclear Information System (INIS)

West, M.H.

1983-03-01

Dinonylnaphthalenesulfonic acid (HDNNS) has been shown to be an effective liquid cation exchanger for the extraction of metal ions. This extractant has proven to be successful in the extraction of trivalent lanthanides and actinides in the pH range of 2.0 to 3.0, although it shows little selectivity for individual ions because of its strong acid character. In an effort to improve the selectivity of HDNNS between trivalent lanthanides and actinides, carboxylic acids were added to the organic phase and the effects on the extraction characteristics of HDNNS were investigated. Three carboxylic acids - nonanoic, cyclohexanecarboxylic, and cyclohexanebutyric - were studied with the following metals: Am(III), Cm(III), Ce(III), Eu(III), and Tm(III). The distributions of the metal ions were studied holding the HDNNS concentration constant while varying the carboxylic acid concentrations over a range of 1.0 x 10 -5 M to 1.0 M. Results indicated that the greatest enhancement of the extraction occurred at a carboxylic acid concentration of 1.0 x 10 -2 M with negative effects occurring at 0.5 M and 1.0 M. The effects on the extraction of the trivalent lanthanides and actinides were interpreted in terms of the structural differences of the carboxylic acids, the effect of the carboxylic acids on the HDNNS extraction mechanism, and the ionic properties of the metals studied

Extraction of actinides from chloride medium using pentaalkylpropanediamides

International Nuclear Information System (INIS)

Cuillerdier, C.; Musikas, C.

1991-01-01

Pyrometallurgical processes for the purification of plutonium create waste solutions containing actinides, mainly americium, in chloride medium. Studies have been undertaken to study the extraction of actinides in chloride medium (hydrochloric acid mixed with concentrated salts such as LiCl, CaCl 2 , MgCl 2 , KCl) using pentaalkylpropanediamides as extractants. Plutonium (IV) is very easily extracted, Am (III) needs a salting out agent such as LiCl. Back extraction of trivalent cations is easy in HCl <5M. Plutonium(IV) and (VI) can be stripped by reduction either with ascorbic acid or hydroxylammonium salts in weak acid medium. Several diluents can be used (aromatic, chlorinated or even aliphatic) with addition of decanol to prevent third phase formation. In conclusion diamides can be used for various wastes declassification, they are potentially completely incinerable, and, as the synthesis has been optimized, they appear to be promising extractants

PRODUCTION OF ACTINIDE METAL

Science.gov (United States)

Knighton, J.B.

1963-11-01

A process of reducing actinide oxide to the metal with magnesium-zinc alloy in a flux of 5 mole% of magnesium fluoride and 95 mole% of magnesium chloride plus lithium, sodium, potassium, calcium, strontium, or barium chloride is presented. The flux contains at least 14 mole% of magnesium cation at 600-- 900 deg C in air. The formed magnesium-zinc-actinide alloy is separated from the magnesium-oxide-containing flux. (AEC)

Liquid-liquid extraction kinetics of uranyl nitrate and actinides (III)-lanthanides nitrates by extractants with amide function

International Nuclear Information System (INIS)

Toulemonde, V.

1995-01-01

Nowadays, the most important part of electric power is generated by fission energy. But spent fuels have then to be reprocessed. The production of these reprocessed materials separately and with a high purity level is done according to a liquid-liquid extraction process (Purex process) with the use of tributyl phosphate as solvent. Optimization studies concerning the extracting agent have been undertaken. This work gives the results obtained for the uranyl nitrate and the actinides (III)-lanthanides (III) nitrates extraction by extractants with amide function (monoamide for U(VI) and diamide for actinides (III) and lanthanides (III)). The extraction kinetics have been studied in the case of a metallic specie transfer from the aqueous phase towards the organic phase. The experiments show that the nitrates extraction kinetics is limited by the complexation chemical reaction of the species at the interface between the two liquids. An adsorption-desorption interfacial reactional mechanism (Langmuir theory) is proposed for the uranyl nitrate. (O.M.)

Molecular and electronic structure of actinide hexa-cyanoferrates; Structure moleculaire et electronique des hexacyanoferrates d'actinides

Energy Technology Data Exchange (ETDEWEB)

Bonhoure, I

2001-07-01

The goal of this work is to improve our knowledge on the actinide-ligand bond properties. To this end, the hexacyanoferrate entities have been used as pre-organized ligand. We have synthesized, using mild chemistry, the following series of complexes: An{sup IV}[Fe{sup II}(CN){sub 6}].xH{sub 2}O (An = Th, U, Np, Pu); Am{sup III}[Fe{sup III}(CN){sub 6}].xH{sub 2}O; Pu {sup III}[Co{sup III}(CN){sub 6}].xH{sub 2}O and K(H?)An{sup III}[Fe{sup II}(CN){sub 6}].xH{sub 2}O (An = Pu, Am). The metal oxidation states have been obtained thanks to the {nu}{sub CN}, stretching vibration and to the actinide L{sub III} absorption edge studies. As Prussian Blue, the An{sup IV}[Fe{sup II}(CN){sub 6}].xH{sub 2}O (An = Np, Pu) are class II of Robin and Day compounds. X-ray Diffraction has shown besides that these complexes crystallize in the P6{sub 3}/m space group, as the isomorphic LaKFe(CN){sub 6}.4H{sub 2}O complex used as structural model. The EXAFS oscillations at the iron K edge and at the An L{sub III} edge allowed to determine the An-N, An-O, Fe-C and Fe-N distances. The display of the multiple scattering paths for both edges explains the actinide contribution absence at the iron edge, whereas the iron signature is present at the actinide edge. We have shown that the actinide coordination sphere in actinides hexa-cyanoferrates is comparable to the one of lanthanides. However, the actinides typical behavior towards the lanthanides is brought to the fore by the An{sup IV} versus Ln{sup III} ions presence in this family of complexes. Contrarily to the 4f electrons, the 5f electrons influence the electronic properties of the compounds of this family. However, the gap between the An-N and Ln-N distances towards the corresponding metals ionic radii do not show any covalence bond evolution between the actinide and lanthanide series. (author)

Study of the selectivity of poly-nitrogenous extracting molecules in the complexation of actinides (III) and lanthanides (III) in solution in anhydrous pyridine

International Nuclear Information System (INIS)

Riviere, Ch.

2000-01-01

The aim of this work is to better understand the factors which contribute to the separation of lanthanides(III) and actinides(III). Polydentate nitrogenous molecules present an interesting selectivity. A thermodynamic study of the complexation in pyridine of lanthanide and uranium by the bipyridine ligand (bipy) has been carried out. The formation constants and the thermodynamic values of the different complexes have been determined. It has been shown that the bipy complexes formation is controlled by the enthalpy and unfavored by the entropy. The conductometry has revealed too a significant difference in the uranium and lanthanides complexation by the bipyridine ligand. The use of the phenanthroline ligand induces a better complexation of the metallic ions but the selectivity is not improved. On the other hand, the decrease of the basicity and the increase of the ligand denticity (for instance in the case of the use of ter-pyridine) favour the selectivity without improving the complexation. The selectivity difference for the complexation of actinides(III) and lanthanides(III) by the different studied ligands (independent systems) has been confirmed by experiments of inter-metals competition. (O.M.)

NMR and TRLFS studies of Ln(iii) and An(iii) C5-BPP complexes.

Science.gov (United States)

Adam, Christian; Beele, Björn B; Geist, Andreas; Müllich, Udo; Kaden, Peter; Panak, Petra J

2015-02-01

C5-BPP is a highly efficient N-donor ligand for the separation of trivalent actinides, An(iii), from trivalent lanthanides, Ln(iii). The molecular origin of the selectivity of C5-BPP and many other N-donor ligands of the BTP-type is still not entirely understood. We present here the first NMR studies on C5-BPP Ln(iii) and An(iii) complexes. C5-BPP is synthesized with 10% 15 N labeling and characterized by NMR and LIFDI-MS methods. 15 N NMR spectroscopy gives a detailed insight into the bonding of C5-BPP with lanthanides and Am(iii) as a representative for trivalent actinide cations, revealing significant differences in 15 N chemical shift for coordinating nitrogen atoms compared to Ln(iii) complexes. The temperature dependence of NMR chemical shifts observed for the Am(iii) complex indicates a weak paramagnetism. This as well as the observed large chemical shift for coordinating nitrogen atoms show that metal-ligand bonding in Am(C5-BPP) 3 has a larger share of covalence than in lanthanide complexes, confirming earlier studies. The Am(C5-BPP) 3 NMR sample is furthermore spiked with Cm(iii) and characterized by time-resolved laser fluorescence spectroscopy (TRLFS), yielding important information on the speciation of trace amounts of minor complex species.

Electrorecovery of actinides at room temperature

Energy Technology Data Exchange (ETDEWEB)

Stoll, Michael E [Los Alamos National Laboratory; Oldham, Warren J [Los Alamos National Laboratory; Costa, David A [Los Alamos National Laboratory

2008-01-01

There are a large number of purification and processing operations involving actinide species that rely on high-temperature molten salts as the solvent medium. One such application is the electrorefining of impure actinide metals to provide high purity material for subsequent applications. There are some drawbacks to the electrodeposition of actinides in molten salts including relatively low yields, lack of accurate potential control, maintaining efficiency in a highly corrosive environment, and failed runs. With these issues in mind we have been investigating the electrodeposition of actinide metals, mainly uranium, from room temperature ionic liquids (RTILs) and relatively high-boiling organic solvents. The RTILs we have focused on are comprised of 1,3-dialkylimidazolium or quaternary ammonium cations and mainly the {sup -}N(SO{sub 2}CF{sub 3}){sub 2} anion [bis(trif1uoromethylsulfonyl)imide {equivalent_to} {sup -}NTf{sub 2}]. These materials represent a class of solvents that possess great potential for use in applications employing electrochemical procedures. In order to ascertain the feasibility of using RTILs for bulk electrodeposition of actinide metals our research team has been exploring the electron transfer behavior of simple coordination complexes of uranium dissolved in the RTIL solutions. More recently we have begun some fundamental electrochemical studies on the behavior of uranium and plutonium complexes in the organic solvents N-methylpyrrolidone (NMP) and dimethylsulfoxide (DMSO). Our most recent results concerning electrodeposition will be presented in this account. The electrochemical behavior of U(IV) and U(III) species in RTILs and the relatively low vapor pressure solvents NMP and DMSO is described. These studies have been ongoing in our laboratory to uncover conditions that will lead to the successful bulk electrodeposition of actinide metals at a working electrode surface at room temperature or slightly elevated temperatures. The RTILs we

Extraction of lanthanides and actinides (III) by DI-2 ethyl dithiophosphoric acid and DI-2 ethyl hexyl monothiophosphoric acid. Structure of the complexes in the organic phase

International Nuclear Information System (INIS)

Pattee, D.; Musikas, C.; Faure, A.; Chachaty, C.

1986-09-01

To operate a trivalent actinide-lanthanide (III) group chemical separation from low pH nitric solutions we studied the extractive properties of the di-2 ethyl hexyl dithiophosphoric acid (HDEHDTP); this bidentate ligand which possesses a sulfur donor atom is a good extractant of soft acids. We so expect a better selectivity for the actinides (III) extraction. We also have investigated extractive properties of di-2 ethyl hexyl monothiophosphoric acid (HDEHTP) for trivalent actinides and lanthanides; HDEHDTP is a bidentate ligand with one oxygen donor atom and so is a better extractant for hard acids like actinides and lanthanides (III); but its selectivity is weak. The addition of TBP (tri-n butyl phosphate) to HDEHDTP deals to strong synergistic organic complexes with a great selectivity for Am(III). We explicited this phenomenon. When the metal is macroconcentrated the organic complexes aggregate and form inverted micelles

Complexation of the actinides (III, IV and V) with organic acids

International Nuclear Information System (INIS)

Leguay, S.

2012-01-01

A thorough knowledge of the chemical properties of actinides is now required in a wide variety of fields: extraction processes involved in spent fuel reprocessing, groundwater in the vicinity of radioactive waste packages, environmental and biological media in the case of accidental release of radionuclides. In this context, the present work has been focused on the complexation of Am(III), Cm(III), Cf(III), Pu(IV) and Pa(V) with organic ligands: DTPA, NTA and citric acid. The complexation of pentavalent protactinium with citric and nitrilotriacetic acids was studied using liquid-liquid extraction with the element at tracer scale (C Pa ≤ 10 -10 M). The order and the mean charge of each complex were determined from the analysis of the systematic variations of the distribution coefficient of Pa(V) as function of ligand and proton concentration. Then, the apparent formation constants related of the so-identified complexes were calculated. The complexation of trivalent actinides with DTPA was studied by fluorescence spectroscopy (TRLFS) and capillary electrophoresis (CE-ICP-MS). The coexistence of the mono-protonated and non-protonated complexes (AnHDTPA - and AnDTPA 2- ) in acidic media (1.5 ≤ pH ≤ 3.5) was shown unambiguously. Literature data have been reinterpreted by taking into account both complexes and a consistent set of formation constants of An(III)-DTPA has been obtained. The experimental study was completed by theoretical calculations (DFT) on Cm-DTPA system. The coordination geometry of Cm in CmDTPA 2- and CmHDTPA - including water molecules in the first coordination sphere has been determined as well as interatomic distances. Finally, a study on the complexation of Pu(IV) with DTPA was initiated in order to more closely mimic physiological conditions. A three-step approach was proposed to avoid plutonium hydrolysis: i/ complexation of Pu(IV) with (NTA) in order to protect Pu(IV) from hydrolysis (at low pH) ii/ increase of pH toward neutral conditions

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

International Nuclear Information System (INIS)

Banik, N.L.; Boris Brendebach; Marquardt, Ch.M.

2014-01-01

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)

Comparative Study of f-Element Electronic Structure across a Series of Multimetallic Actinide, Lanthanide-Actinide and Lanthanum-Actinide Complexes Possessing Redox-Active Bridging Ligands

Energy Technology Data Exchange (ETDEWEB)

Schelter, Eric J.; Wu, Ruilian; Veauthier, Jacqueline M.; Bauer, Eric D.; Booth, Corwin H.; Thomson, Robert K.; Graves, Christopher R.; John, Kevin D.; Scott, Brian L.; Thompson, Joe D.; Morris, David E.; Kiplinger, Jaqueline L.

2010-02-24

A comparative examination of the electronic interactions across a series of trimetallic actinide and mixed lanthanide-actinide and lanthanum-actinide complexes is presented. Using reduced, radical terpyridyl ligands as conduits in a bridging framework to promote intramolecular metal-metal communication, studies containing structural, electrochemical, and X-ray absorption spectroscopy are presented for (C{sub 5}Me{sub 5}){sub 2}An[-N=C(Bn)(tpy-M{l_brace}C{sub 5}Me4R{r_brace}{sub 2})]{sub 2} (where An = Th{sup IV}, U{sup IV}; Bn = CH{sub 2}C{sub 6}H{sub 5}; M = La{sup III}, Sm{sup III}, Yb{sup III}, U{sup III}; R = H, Me, Et) to reveal effects dependent on the identities of the metal ions and R-groups. The electrochemical results show differences in redox energetics at the peripheral 'M' site between complexes and significant wave splitting of the metal- and ligand-based processes indicating substantial electronic interactions between multiple redox sites across the actinide-containing bridge. Most striking is the appearance of strong electronic coupling for the trimetallic Yb{sup III}-U{sup IV}-Yb{sup III}, Sm{sup III}-U{sup IV}-Sm{sup III}, and La{sup III}-U{sup IV}-La{sup III} complexes, [8]{sup -}, [9b]{sup -} and [10b]{sup -}, respectively, whose calculated comproportionation constant K{sub c} is slightly larger than that reported for the benchmark Creutz-Taube ion. X-ray absorption studies for monometallic metallocene complexes of U{sup III}, U{sup IV}, and U{sup V} reveal small but detectable energy differences in the 'white-line' feature of the uranium L{sub III}-edges consistent with these variations in nominal oxidation state. The sum of this data provides evidence of 5f/6d-orbital participation in bonding and electronic delocalization in these multimetallic f-element complexes. An improved, high-yielding synthesis of 4{prime}-cyano-2,2{prime}:6{prime},2{double_prime}-terpyridine is also reported.

Research for actinides extractants from various wastes

International Nuclear Information System (INIS)

Musikas, C.; Cuillerdier, C.; Condamines, N.

1990-01-01

This paper is an overview of the actinides solvent extraction research undertaken in Fontenay-aux-Roses. Two kinds of extractants are investigated; those usable for the improvement of the nowadays nuclear fuels reprocessing and those necessary for advanced fuels cycles which include the minor actinides (Np, Am) recovery for a further elimination through nuclear reactions. In the first class the mono and diamides, alternative to the organophosphorus extractants, TBP and polyfunctional phosphonates, showed promising properties. The main results are discussed. For the future efficient extractants for trivalent actinides-lanthanides group separations are suitable. The point about the actinides (III) - lanthanides (III) group separation chemistry and the development of some of these extractants are given

Actinides and rare earths complexation with adenosine phosphate nucleotides

International Nuclear Information System (INIS)

Mostapha, Sarah

2013-01-01

Organophosphorus compounds are important molecules in both nuclear industry and living systems fields. Indeed, several extractants of organophosphorus compounds (such as TBP, HDEHP) are used in the nuclear fuel cycle reprocessing and in the biological field. For instance, the nucleotides are organophosphates which play a very important role in various metabolic processes. Although the literature on the interactions of actinides with inorganic phosphate is abundant, published studies with organophosphate compounds are generally limited to macroscopic and / or physiological approaches. The objective of this thesis is to study the structure of several organophosphorus compounds with actinides to reach a better understanding and develop new specific buildings blocks. The family of the chosen molecules for this procedure consists of three adenine nucleotides mono, bi and triphosphate (AMP, adenosine monophosphate - ADP, adenosine diphosphate - ATP, adenosine triphosphate) and an amino-alkylphosphate (AEP O-phosphoryl-ethanolamine). Complexes synthesis was conducted in aqueous and weakly acidic medium (2.8-4) for several lanthanides (III) (Lu, Yb, Eu) and actinides (U (VI), Th (IV) and Am (III)). Several analytical and spectroscopic techniques have been used to describe the organization of the synthesized complexes: spectrometric analysis performed by FTIR and NMR were used to identify the functional groups involved in the complexation, analysis by ESI-MS and pH-metric titration were used to determine the solution speciation and EXAFS analyzes were performed on Mars beamline of the SOLEIL synchrotron, have described the local cation environment, for both solution and solid compounds. Some theoretical approaches of DFT were conducted to identify stable structures in purpose of completing the experimental studies. All solid complexes (AMP, ADP, ATP and AEP) have polynuclear structures, while soluble ATP complexes are mononuclear. For all synthesized complexes, it has been

The nature of chemical bonding in actinide and lanthanide ferrocyanides determined by X-ray absorption spectroscopy and density functional theory.

Science.gov (United States)

Dumas, Thomas; Guillaumont, Dominique; Fillaux, Clara; Scheinost, Andreas; Moisy, Philippe; Petit, Sébastien; Shuh, David K; Tyliszczak, Tolek; Den Auwer, Christophe

2016-01-28

The electronic properties of actinide cations are of fundamental interest to describe intramolecular interactions and chemical bonding in the context of nuclear waste reprocessing or direct storage. The 5f and 6d orbitals are the first partially or totally vacant states in these elements, and the nature of the actinide ligand bonds is related to their ability to overlap with ligand orbitals. Because of its chemical and orbital selectivities, X-ray absorption spectroscopy (XAS) is an effective probe of actinide species frontier orbitals and for understanding actinide cation reactivity toward chelating ligands. The soft X-ray probes of the light elements provide better resolution than actinide L3-edges to obtain electronic information from the ligand. Thus coupling simulations to experimental soft X-ray spectral measurements and complementary quantum chemical calculations yields quantitative information on chemical bonding. In this study, soft X-ray XAS at the K-edges of C and N, and the L2,3-edges of Fe was used to investigate the electronic structures of the well-known ferrocyanide complexes K4Fe(II)(CN)6, thorium hexacyanoferrate Th(IV)Fe(II)(CN)6, and neodymium hexacyanoferrate KNd(III)Fe(II)(CN)6. The soft X-ray spectra were simulated based on quantum chemical calculations. Our results highlight the orbital overlapping effects and atomic effective charges in the Fe(II)(CN)6 building block. In addition to providing a detailed description of the electronic structure of the ferrocyanide complex (K4Fe(II)(CN)6), the results strongly contribute to confirming the actinide 5f and 6d orbital oddity in comparison to lanthanide 4f and 5d.

Actinide uptake by transferrin and ferritin metalloproteins

International Nuclear Information System (INIS)

Den Auwer, C.; Llorens, I.; Moisy, Ph.; Vidaud, C.; Goudard, F.; Barbot, C.; Solari, P.L.; Funke, H.

2005-01-01

In order to better understand the mechanisms of actinide uptake by specific biomolecules, it is essential to explore the intramolecular interactions between the cation and the protein binding site. Although this has long been done for widely investigated transition metals, very few studies have been devoted to complexation mechanisms of actinides by active chelation sites of metalloproteins. In this field, X-ray absorption spectroscopy has been extensively used as a structural and electronic metal cation probe. The two examples that are presented here are related to two metalloproteins in charge of iron transport and storage in eukaryote cells: transferrin and ferritin. U(VI)O 2 2+ , Np(IV) and Pu(IV) have been selected because of their possible role as contaminant from the geosphere. (orig.)

Advanced Extraction Methods for Actinide/Lanthanide Separations

International Nuclear Information System (INIS)

Scott, M.J.

2005-01-01

high level liquid wastes and a general actinide clean-up procedure. The selectivity of the standard extractant for tetravalent actinides, (N,N-diisobutylcarbamoylmethyl) octylphenylphosphineoxide (CMPO), was markedly improved by the attachment of three CMPO-like functions onto a triphenoxymethane platform, and a ligand that is both highly selective and effective for An(IV) ions was isolated. A 10 fold excess of ligand will remove virtually all of the 4+ actinides from the acidic layer without extracting appreciable quantities of An(III) and Ln(III) unlike simple CMPO ligands. Inspired by the success of the DIAMEX industrial process for extractions, three new tripodal chelates bearing three diglycolamide and thiodiglycolamide units precisely arranged on a triphenoxymethane platform have been synthesized for an highly efficient extraction of trivalent f-element cations from nitric acid media. A single equivalent of ligand will remove 80% of the Ln(III) ion from the acidic layer since the ligand is perfectly suited to accommodate the tricapped trigonal prismatic geometry preferred by the metal center. The ligand is perhaps the most efficient binder available for the heavier lanthanides and due to this unique attribute, the extraction event can be easily followed by 1H NMR spectroscopy confirming the formation of a TPP complex. The most lipophilic di-n-butyl tris-diglycolamide was found to be a significantly weaker extractant in comparison to the di-isopropyl analogs. The tris-thiodiglycolamide derivative proved to be an ineffective chelate for f-elements and demonstrated the importance of the etheric oxygens in the metal binding. The results presented herein clearly demonstrate a cooperative action of these three ligating groups within a single molecule, confirmed by composition and structure of the extracted complexes, and since actinides prefer to have high coordination numbers, the ligands should be particularly adept at binding with three arms. The use of such an

Advanced Extraction Methods for Actinide/Lanthanide Separations

Energy Technology Data Exchange (ETDEWEB)

Scott, M.J.

2005-12-01

high level liquid wastes and a general actinide clean-up procedure. The selectivity of the standard extractant for tetravalent actinides, (N,N-diisobutylcarbamoylmethyl) octylphenylphosphineoxide (CMPO), was markedly improved by the attachment of three CMPO-like functions onto a triphenoxymethane platform, and a ligand that is both highly selective and effective for An(IV) ions was isolated. A 10 fold excess of ligand will remove virtually all of the 4+ actinides from the acidic layer without extracting appreciable quantities of An(III) and Ln(III) unlike simple CMPO ligands. Inspired by the success of the DIAMEX industrial process for extractions, three new tripodal chelates bearing three diglycolamide and thiodiglycolamide units precisely arranged on a triphenoxymethane platform have been synthesized for an highly efficient extraction of trivalent f-element cations from nitric acid media. A single equivalent of ligand will remove 80% of the Ln(III) ion from the acidic layer since the ligand is perfectly suited to accommodate the tricapped trigonal prismatic geometry preferred by the metal center. The ligand is perhaps the most efficient binder available for the heavier lanthanides and due to this unique attribute, the extraction event can be easily followed by 1H NMR spectroscopy confirming the formation of a TPP complex. The most lipophilic di-n-butyl tris-diglycolamide was found to be a significantly weaker extractant in comparison to the di-isopropyl analogs. The tris-thiodiglycolamide derivative proved to be an ineffective chelate for f-elements and demonstrated the importance of the etheric oxygens in the metal binding. The results presented herein clearly demonstrate a cooperative action of these three ligating groups within a single molecule, confirmed by composition and structure of the extracted complexes, and since actinides prefer to have high coordination numbers, the ligands should be particularly adept at binding with three arms. The use of such an

Actinide partitioning-transmutation program final report. III. Transmutation studies

International Nuclear Information System (INIS)

Wachter, J.W.; Croff, A.G.

1980-07-01

Transmutation of the long-lived nuclides contained in fuel cycle wastes has been suggested as a means of reducing the long-term toxicity of the wastes. A comprehensive program to evaluate the feasibility and incentives for recovering the actinides from wastes (partitioning) and transmuting them to short-lived or stable nuclides has been in progress for 3 years under the direction of Oak Ridge National Laboratory (ORNL). This report constitutes the final assessment of transmutation in support of this program. Included are (1) a summary of recent transmutation literature, (2) a generic evaluation of actinide transmutation in thermal, fast, and other transmutation devices, (3) a preliminary evaluation of 99 Tc and 129 I transmutation, and (4) a characterization of a pressurized-water-reactor fuel cycle with and without provisions for actinide recovery and transmutation for use in other parts of the ORNL program. The principal conclusion of the report is that actinide transmutation is feasible in both thermal and fast reactors, subject to demonstrating satisfactory fuel performance, with relatively little impact on the reactor. It would also appear that additional transmutation studies are unwarranted until a firm decision to proceed with actinide transmutation has been made by the responsible authorities

Study of extraction kinetics of lanthanides(III) and actinides(III) nitrates by the molecule N, N'-dimethyl-N, N'-dibutyl, tetradecylmalonamide

International Nuclear Information System (INIS)

Daldon, M.

1999-01-01

The kinetics of extraction of lanthanides (III) and actinides (III) nitrates by the molecule N, N'-dimethyl - N, N'-dibutyl tetra-decyl malonamide has been investigated. This study was realised with a new constant interfacial-area-stirred cell. During the qualification step of the device it appears that the reduction of the device can lead to hydrolytic perturbations. The main conclusions are: - after the determination of conditions which provide kinetics regime (diffusion of species neglectable), partial orders of the kinetics law have been obtained and lead to the establishment of the law J = k [Nd 3+ ] [NO 3 - ] 3 [diamide] 1 , - interfacial tension measurements and kinetics study in presence of surface-active compounds proved that the chemical limiting reaction for Nd(III) is interfacial, - the results allow to propose an adsorption-desorption reaction mechanism, - a comprehensive study of the extraction kinetics of the lanthanides(III) series and also Am(III) and Cm(III) nitrates has been realised. The lighter lanthanides (La, Ce and Pr) exhibit higher kinetics rate of extraction than the others, which differs from the tendency observed with distribution coefficients which exhibit tetrad effect. The kinetics rate of extraction of Am(III) and Cm(III) is closed to the value of Eu(III). (author)

Combined techniques for studying actinide complexes in room temperature ionic liquids

International Nuclear Information System (INIS)

Gaillard, C.; Billard, I.; Mekki, S.; Ouadi, A.; Hennig, Ch.; Denecke, M.A.

2007-01-01

Room temperature ionic liquids (RTILs) are a new class of solvents. Their main interest is related to their 'green' properties (non-volatile, non-flammable, etc.), but also from the variability of their physico-chemical properties (stability, hydrophobicity, viscosity) as a function of the RTIL cationic and anionic components. In the frame of the nuclear fuel reprocessing, RTILs are particularly attractive in order to improve existing processes or to develop new ones for actinide and lanthanide partitioning, in replacement of toxic solvents used nowadays, for metal electrodeposition or for liquid/liquid extraction by the use of task specific ionic liquids. However, despite the increasing number of publications devoted to ionic liquids, the solvation effects, the solute-solvent and solvent-solvent interactions are still hardly known. These fundamental aspects are of tremendous importance to the understanding of the solvating properties of these new solvents. In this frame, we have undertaken studies on the solvation and complexation of lanthanides (III) and actinides in RTILs, by the use of spectroscopic techniques. Experiments were led in various ionic liquids in order to highlight the role of the anionic part of the RTILs on the reactivity of the studied cations. Results have clearly shown that solvation phenomena in RTILs are not as 'simple' as in classical solvents. The dissolution of a Ln/An salt, even if complete, does not imply dissociation and solvation of the metal cation by the RTILs anions only. The nature of first co-ordination sphere of Ln/An depends on the competition between its counter-anions and the RTIL anions, which, in turn, influence the complexation reaction with other added anions such as chlorides. (authors)

Environmentally-relevant concentrations of Al(III) and Fe(III) cations induce aggregation of free DNA by complexation with phosphate group.

Science.gov (United States)

Qin, Chao; Kang, Fuxing; Zhang, Wei; Shou, Weijun; Hu, Xiaojie; Gao, Yanzheng

2017-10-15

Environmental persistence of free DNA is influenced by its complexation with other chemical species and its aggregation mechanisms. However, it is not well-known how naturally-abundant metal ions, e.g., Al(III) and Fe(III), influence DNA aggregation. This study investigated aggregation behaviors of model DNA from salmon testes as influenced by metal cations, and elucidated the predominant mechanism responsible for DNA aggregation. Compared to monovalent (K + and Na + ) and divalent (Ca 2+ and Mg 2+ ) cations, Al(III) and Fe(III) species in aqueous solution caused rapid DNA aggregations. The maximal DNA aggregation occurred at 0.05 mmol/L Al(III) or 0.075 mmol/L Fe(III), respectively. A combination of atomic force microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy revealed that Al(III) and Fe(III) complexed with negatively charged phosphate groups to neutralize DNA charges, resulting in decreased electrostatic repulsion and subsequent DNA aggregation. Zeta potential measurements and molecular computation further support this mechanism. Furthermore, DNA aggregation was enhanced at higher temperature and near neutral pH. Therefore, DNA aggregation is collectively determined by many environmental factors such as ion species, temperature, and solution pH. Copyright © 2017 Elsevier Ltd. All rights reserved.

On-line separation of Pu(III) and Am(III) using extraction and ion chromatography

International Nuclear Information System (INIS)

Jernstroem, J.; Lehto, J.; Betti, M.

2007-01-01

An on-line method developed for separating plutonium and americium was developed. The method is based on the use of HPLC pump with three analytical chromatographic columns. Plutonium is reduced throughout the procedure to trivalent oxidation state, and is recovered in the various separation steps together with americium. Light lanthanides and trivalent actinides are separated with TEVA resin in thiocyanate/formic acid media. Trivalent plutonium and americium are pre-concentrated in a TCC-II cation-exchange column, after which the separation is performed in CS5A ion chromatography column by using two different eluents. Pu(III) is eluted with a dipicolinic acid eluent, and Am(III) with oxalic acid eluent. Radiochemical and chemical purity of the eluted plutonium and americium fractions were ensured with alpha-spectrometry. (author)

Study of extraction kinetics of lanthanides(III) and actinides(III) nitrates by the molecule N, N'-dimethyl-N, N'-dibutyl, tetradecylmalonamide; Etude des cinetiques d'extraction des nitrates de lanthanides (III) et d'actinides (III) par le malonamide N, N'-dimethyl-N, N'-dibutyl, tetradecylmalonamide

Energy Technology Data Exchange (ETDEWEB)

Daldon, M

1999-07-01

The kinetics of extraction of lanthanides (III) and actinides (III) nitrates by the molecule N, N'-dimethyl - N, N'-dibutyl tetra-decyl malonamide has been investigated. This study was realised with a new constant interfacial-area-stirred cell. During the qualification step of the device it appears that the reduction of the device can lead to hydrolytic perturbations. The main conclusions are: - after the determination of conditions which provide kinetics regime (diffusion of species neglectable), partial orders of the kinetics law have been obtained and lead to the establishment of the law J = k [Nd{sup 3+}] [NO{sub 3}{sup -}]{sup 3} [diamide]{sup 1}, - interfacial tension measurements and kinetics study in presence of surface-active compounds proved that the chemical limiting reaction for Nd(III) is interfacial, - the results allow to propose an adsorption-desorption reaction mechanism, - a comprehensive study of the extraction kinetics of the lanthanides(III) series and also Am(III) and Cm(III) nitrates has been realised. The lighter lanthanides (La, Ce and Pr) exhibit higher kinetics rate of extraction than the others, which differs from the tendency observed with distribution coefficients which exhibit tetrad effect. The kinetics rate of extraction of Am(III) and Cm(III) is closed to the value of Eu(III). (author)

Synthesis and Evaluation of new Polyfunctional Molecules for Group Actinide Extraction

International Nuclear Information System (INIS)

Marie, C.

2009-10-01

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 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 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)

Mechanisms for the reduction of actinide ions by Geobacter sulfurreducens

International Nuclear Information System (INIS)

Renshaw, J.C.; Livens, F.R.; May, I.; Lloyd, J.R.

2005-01-01

Full text of publication follows: Three of the most problematic radioactive contaminants are the actinide elements uranium, neptunium and plutonium. All three pose considerable long-term environmental risks. The most stable environmental oxidation states of uranium and neptunium are VI and V, respectively, as the di-oxo cations [UO 2 ] 2+ and [NpO 2 ] + ; both are highly soluble and so are relatively mobile and biologically available in the environment. In similar conditions, plutonium mainly exists as Pu(IV), which forms a highly insoluble hydrous oxide, although is also environmentally stable in the more soluble III, V and VI oxidation states. The bio-reduction of U(VI) by anaerobic subsurface microorganisms has been the focus of much recent interest. Both Fe(III)- and sulfate-reducing bacteria have been shown to reduce soluble [U VI O 2 ] 2+ to insoluble U IV O 2 , with c-type cytochromes involved in electron transfer to the actinide. Such transformations offer a strategy for the bio-remediation of uranium contaminated groundwater and a potential mechanism for the bio-deposition of uranium ores. The mechanism of U(VI). reduction has important implications for the potential microbial reduction of transuranic elements with environmentally stable lower oxidation states. Reduction of mobile 237 Np(V) to Np(IV) and subsequent precipitation may be advantageous whilst remobilization of immobile Pu(IV) as more soluble Pu(III) species could have important environmental implications. Conversely, selective reduction might allow targeting of particular radionuclide species. The model anaerobic bacterium Geobacter sulfurreducens is typical of those found in contaminated subsurface environments and has been shown to reduce soluble [U VI O 2 ] 2+ to insoluble U IV O 2 . In the course of this study we use X-ray absorption spectroscopy (XAS) to show that G. sulfurreducens reduces U(VI) by a one-electron reduction, forming an unstable [UO 2 ] + species which subsequently

Innovative SANEX process for trivalent actinides separation from PUREX raffinate

International Nuclear Information System (INIS)

Sypula, Michal

2013-01-01

Recycling of nuclear spent fuel and reduction of its radiotoxicity by separation of long-lived radionuclides would definitely help to close the nuclear fuel cycle ensuring sustainability of the nuclear energy. Partitioning of the main radiotoxicity contributors followed by their conversion into short-lived radioisotopes is known as partitioning and transmutation strategy. To ensure efficient transmutation of the separated elements (minor actinides) the content of lanthanides in the irradiation targets has to be minimised. This objective can be attained by solvent extraction using highly selective ligands that are able to separate these two groups of elements from each other. The objective of this study was to develop a novel process allowing co-separation of minor actinides and lanthanides from a high active acidic feed solution with subsequent actinide recovery using just one cycle, so-called innovative SANEX process. The conditions of each step of the process were optimised to ensure high actinide separation efficiency. Additionally, screening tests of several novel lipophilic and hydrophilic ligands provided by University of Twente were performed. These tests were aiming in better understanding the influence of the extractant structural modifications onto An(III)/Ln(III) selectivity and complexation properties. Optimal conditions for minor actinides separation were found and a flow-sheet of a new innovative SANEX process was proposed. Tests using a single centrifugal contactor confirmed high Eu(III)/Am(III) separation factor of 15 while the lowest SF Ln/Am obtained was 6,5 (for neodymium). In addition, a new masking agent for zirconium was found as a substitution for oxalic acid. This new masking agent (CDTA) was also able to mask palladium without any negative influence on An(III)/Ln(III). Additional tests showed no influence of CDTA on plutonium present in the feed solution unlike oxalic acid which causes Pu precipitation. Therefore, CDTA was proposed as a Zr

Innovative SANEX process for trivalent actinides separation from PUREX raffinate

Energy Technology Data Exchange (ETDEWEB)

Sypula, Michal

2013-07-01

Recycling of nuclear spent fuel and reduction of its radiotoxicity by separation of long-lived radionuclides would definitely help to close the nuclear fuel cycle ensuring sustainability of the nuclear energy. Partitioning of the main radiotoxicity contributors followed by their conversion into short-lived radioisotopes is known as partitioning and transmutation strategy. To ensure efficient transmutation of the separated elements (minor actinides) the content of lanthanides in the irradiation targets has to be minimised. This objective can be attained by solvent extraction using highly selective ligands that are able to separate these two groups of elements from each other. The objective of this study was to develop a novel process allowing co-separation of minor actinides and lanthanides from a high active acidic feed solution with subsequent actinide recovery using just one cycle, so-called innovative SANEX process. The conditions of each step of the process were optimised to ensure high actinide separation efficiency. Additionally, screening tests of several novel lipophilic and hydrophilic ligands provided by University of Twente were performed. These tests were aiming in better understanding the influence of the extractant structural modifications onto An(III)/Ln(III) selectivity and complexation properties. Optimal conditions for minor actinides separation were found and a flow-sheet of a new innovative SANEX process was proposed. Tests using a single centrifugal contactor confirmed high Eu(III)/Am(III) separation factor of 15 while the lowest SF{sub Ln/Am} obtained was 6,5 (for neodymium). In addition, a new masking agent for zirconium was found as a substitution for oxalic acid. This new masking agent (CDTA) was also able to mask palladium without any negative influence on An(III)/Ln(III). Additional tests showed no influence of CDTA on plutonium present in the feed solution unlike oxalic acid which causes Pu precipitation. Therefore, CDTA was proposed as

MICROBIAL IMPACTS ON THE MIGRATION OF ACTINIDES -EFFECTS OF EXUDATES ON ADSORPTION-

International Nuclear Information System (INIS)

OHNUKI, T.; OZAKI, T.; YOSHIDA, T.; NANKAWA, T.; KOZAI, N.; SAKAMOTO, F.; SUZUKI, Y.; FRANCIS, A.J.

2006-01-01

The interaction of actinides with microorganisms has been extensively studied to elucidate migration behavior of actinides in the environments. However, the mechanisms of interaction of microorganisms and actinides are poorly understood. They have been conducting basic science on microbial accumulation of actinides in order to elucidate the environmental behavior of actinides under relevant conditions. The effect of exudates from bacteria cells on the sorption of Eu(III) and Cm(III) by Chlorella vulgaris was studied by a batch method. The pH dependence of log K d of Eu(III) and Cm(III) for cellulose, major component of C. vulgaris cell, differed from that for C. vulgaris. On the contrary, log K d of Eu(III) and Cm(III) for cellulose in the solution containing exudates from C. vulgaris cells in a 0.5% NaCl solution showed a similar pH dependence to that by C. vulgaris. These results strongly suggested that exudates affect on the sorption of Eu(III) and Cm(III) on C. vulgaris. Effect of desferrioxamine B (DFO), one of exudates to chelate the insoluble Fe(III), on the sorption of Pu(IV), Th(IV) and Eu(III) by Pseudomonas fluorescens was studied. In the presence of DFO the sorption of Pu(IV), Th(IV) and Eu(III) on the cells increased with a decrease in pH from 7 to 4. In contrast, without DFO most of Pu(IV), Th(IV) and Eu(III) were precipitated from solution. Adsorption of DFO on the cells was negligible in the solution with and without metals. Adsorption of Pu(IV), Th(IV) and Eu(III) on P. fluorescens cells decreased in the order Eu(III) > Th(IV) > Pu(IV), which corresponds to increasing stability constant of the DFO complexes. These results indicate that Th(IV), Pu(IV) and Eu(III) dissociate when in contact with cells, after which the metals are adsorbed

Microbial impacts on the migration of actinides. Effects of exudates on adsorption

International Nuclear Information System (INIS)

Ohnuki, Toshihiko; Ozaki, Takuo; Nakawa, Takuya; Kozai, Naofumi; Sakamoto, Fuminori; Suzuki, Yosinori; Yoshida, Takahiro; Francis, Arokiasamy J.

2007-01-01

The interaction of actinides with microorganisms has been extensively studied to elucidate migration behavior of actinides in the environments. However, the mechanisms of interaction of microorganisms and actinides are poorly understood. We have been conducting basic science on microbial accumulation of actinides in order to elucidate the environmental behavior of actinides under relevant conditions. The effect of exudates from bacteria cells on the sorption of Eu(III) and Cm(III) by Chlorella vulgaris was studied by a batch method. The pH dependence of log K d of Eu(III) and Cm(III) for cellulose, major component of C. vulgaris cell, differed from that for C. vulgaris. On the contrary, log K d of Eu(III) and Cm(III) for cellulose in the solution containing exudates from C. vulgaris cells in a 0.5% NaCl solution showed a similar pH dependence to that by C. vulgaris. These results strongly suggested that exudates affect on the sorption of Eu(III) and Cm(III) on C. vulgaris. Effect of desferrioxamine B (DFO), one of exudates to chelate with insoluble Fe(III), on the sorption of Pu(IV), Th(IV) and Eu(III) by Pseudomonas fluorescens was studied. In the presence of DFO the sorption of Pu(IV), Th(IV) and Eu(III) on the cells increased with a decrease in pH from 7 to 4. In contrast, without DFO most of Pu(IV), Th(IV) and Eu(III) were precipitated from solution. Adsorption of DFO on the cells was negligible in the solution with and without metals. Adsorption of Pu(IV), Th(IV) and Eu(III) on P. fluorescens cells decreased in the order Eu(III) > Th(IV) > Pu(IV), which corresponds to increasing stability constant of the DFO complexes. These results indicate that Th(IV), Pu(IV) and Eu(III) dissociate when in contact with cells, after which the metals are adsorbed. (author)

Complexation of trivalent actinides and lanthanides with hydrophilic N-donor ligands for Am(III)/Cm(III) and An(III)/Ln(III) separation; Komplexierung von trivalenten Actiniden und Lanthaniden mit hydrophilen N-Donorliganden zur Am(III)/Cm(III)- bzw. An(III)/Ln(III)-Trennung

Energy Technology Data Exchange (ETDEWEB)

Wagner, Christoph

2017-07-24

The implementation of actinide recycling processes is considered in several countries, aiming at the reduction of long-term radiotoxicity and heat load of used nuclear fuel. This requires the separation of the actinides from the fission and corrosion products. The separation of the trivalent actinides (An(III)) Am(III) and Cm(III), however, is complicated by the presence of the chemically similar fission lanthanides (Ln(III)). Hydrophilic N-donor ligands are employed as An(III) or Am(III) selective complexing agents in solvent extraction to strip An(III) or Am(III) from an organic phase loaded with An(III) and Ln(III). Though they exhibit excellent selectivity, the complexation chemistry of these ligands and the complexes formed during solvent extraction are not sufficiently characterized. In the present thesis the complexation of An(III) and Ln(III) with hydrophilic N-donor ligands is studied by time resolved laser fluorescence spectroscopy (TRLFS), UV/Vis, vibronic sideband spectroscopy and solvent extraction. TRLFS studies on the complexation of Cm(III) and Eu(III) with the Am(III) selective complexing agent SO{sub 3}-Ph-BTBP (tetrasodium 3,3{sup '},3'',3{sup '''}-([2,2{sup '}-bipyridine]-6,6{sup '}-diylbis(1,2,4-triazine-3,5,6-triyl)) tetrabenzenesulfonate) revealed the formation of [M(SO{sub 3}-Ph-BTBP){sub n}]{sup (4n-3)-} complexes (M = Cm(III), Eu(III); n = 1, 2). The conditional stability constants were determined in different media yielding two orders of magnitude larger β{sub 2}-values for the Cm(III) complexes, independently from the applied medium. A strong impact of ionic strength on the stability and stoichiometry of the formed complexes was identified, resulting from the stabilization of the pentaanionic [M(SO{sub 3}-Ph-BTBP){sub 2}]{sup 5-} complex with increasing ionic strength. Thermodynamic studies of Cm(III)-SO{sub 3}-Ph-BTBP complexation showed that the proton concentration of the applied medium impacts

Liquid-solid extraction of metallic cations by cationic amphiphiles

International Nuclear Information System (INIS)

Mueller, Wolfram; Sievers, Torsten K.; Zemb, Thomas; Diat, Olivier; Sievers, Torsten K.; Dejugnat, Christophe

2012-01-01

In the field of selective metal ion separation, liquid-liquid extraction is usually conducted through an emulsion mixing of hydrophobic complexants dispersed in an organic phase and acidic water containing the ionic species. Recently, it has been shown that amphiphilic complexants could influence strongly extraction efficiency by enhancing the interfacial interaction between the metal ion in the aqueous and the complexant in the organic phase. Moreover, these amphiphiles can also substitute the organic phase if an appropriate aliphatic chain is chosen. The dispersion of such amphiphilic complexants in an aqueous solution of salt mixtures is not only attractive for studying specific interactions but also to better the understanding of complex formation in aqueous solution of multivalent metal ions, such as lanthanides and actinides. This understanding is of potential interest for a broad range of industries including purification of rare earth metals and pollute treatment e.g. of fission byproducts. This principle can also be applied to liquid-solid extraction, where the final state of the separation is a solid phase containing the selectively extracted ions. Indeed, a novel solid-liquid extraction method exploits the selective precipitation of metal ions from an aqueous salt mixture using a cationic surfactant, below its Krafft point (temperature below which the long aliphatic chains of surfactant crystallize). This technique has been proven to be highly efficient for the separation of actinides and heavy metal using long chain ammonium or pyridinium amphiphiles. The most important point in this process is the recognition of cationic metal ions by cationic surfactants. By computing the free energy of the polar head group per micelle as a function of the different counter-anions, we have demonstrated for the first time that different interactions exist between the micellar surface and the ions. These interactions depend on the nature of the cation but also on

Photochemical reactions of actinide ions

International Nuclear Information System (INIS)

Tomiyasu, Hiroshi

1995-01-01

This paper reviews the results of photochemical studies of actinide ions, which have been performed in our research group for past several years as follows: I) behavior of the excited uranyl(VI) ion; II) photo-reductions of the uranyl ion with organic and inorganic compounds; III) photo-oxidations of uranium(IV) and plutonium(III) in nitric acid solutions. (author)

Physico-chemistry of actinides and other radioelements in solutions and at the interfaces

International Nuclear Information System (INIS)

2000-01-01

This document provides the 61 papers (transparencies used during the presentations and posters) presented at the 1999 PRACTIS days, held February 17-18, 2000 in Villeneuve-les-Avignon. The content comprises 9 conferences dealing with 1)simulation of solvation, coordination and liquid-liquid extraction of rare earth and uranyl cations 2)overview on the complexation selectivity of actinides(III) and rare earths(III) by aromatic poly-nitrogenous ligands 3)detection, characterization and interaction between supramolecular aggregates of extractants: macroscopic consequences on the stability and on the macroscopic behaviour 4)chemistry of technetium in reducing medium: application to researches on radioactive waste management 5) separations by pyro-chemistry (CEA program) 6)overview on the Goethite operation 7)use of time-resolved luminescence spectroscopy to the determination of sorption sites at the interfaces 8)dissolution of uranium dioxide in an argillaceous water: results in oxidizing and reducing conditions 9)treatment and storage of radioactive wastes from weapon-grade plutonium production in Russia and other countries. A large part of the conference was devoted to poster sessions on the following topics: physico-chemistry in homogeneous solutions (22 posters), transfer kinetics of actinides and rare earths between liquid phases and separations (9 posters), physico-chemistry of the solid-solution interface (9 posters), simulation and molecular dynamics (5 posters), uranium dioxide and other oxides (1 poster), long-lived fission products (6 posters). (O.M.)

Methods for separating actinides from reprocessing and refabrication plant wastes

International Nuclear Information System (INIS)

Tedder, D.W.; Finney, B.C.; Blomeke, J.O.

1979-01-01

Chemical processing flowsheets have been developed to partition actinides from all actinide-bearing LWR fuel reprocessing and refabrication plant wastes. These wastes include high-activity-level liquids, scrap recovery liquors, HEPA filters and incinerator ashes, and chemical salt wastes such as sodium carbonate scrub solutions, detergent cleanup streams, and alkaline off-gas scrubber liquors. The separations processes that were adopted for this study are based on solvent extraction, cation exchange chromatography, and leaching with Ce 4+ -HNO 3 solution

Actinide metals

Energy Technology Data Exchange (ETDEWEB)

Brown, Paul L. [Geochem Australia, Kiama, NSW (Australia); Ekberg, Christian [Chalmers Univ. of Technology, Goeteborg (Sweden). Nuclear Chemistry/Industrial Materials Recycling

2016-07-01

All isotopes of actinium are radioactive and exist in aqueous solution only in the trivalent state. There have been very few studies on the hydrolytic reactions of actinium(III). The hydrolysis reactions for uranium would only be important in alkaline pH conditions. Thermodynamic parameters for the hydrolysis species of uranium(VI) and its oxide and hydroxide phases can be determined from the stability and solubility constants. The hydrolytic behaviour of neptunium(VI) is quite similar to that of uranium(VI). The solubility constant of NpO{sub 2}OH(am) has been reported a number of times for both zero ionic strength and in fixed ionic strength media. Americium can form four oxidation states in aqueous solution, namely trivalent, tetravalent, pentavalent and hexavalent. Desire, Hussonnois and Guillaumont determined stability constants for the species AmOH{sup 2+} for the actinides, plutonium(III), americium(III), curium(III), berkelium(III) and californium(III) using a solvent extraction technique.

Actinide metals

International Nuclear Information System (INIS)

Brown, Paul L.; Ekberg, Christian

2016-01-01

All isotopes of actinium are radioactive and exist in aqueous solution only in the trivalent state. There have been very few studies on the hydrolytic reactions of actinium(III). The hydrolysis reactions for uranium would only be important in alkaline pH conditions. Thermodynamic parameters for the hydrolysis species of uranium(VI) and its oxide and hydroxide phases can be determined from the stability and solubility constants. The hydrolytic behaviour of neptunium(VI) is quite similar to that of uranium(VI). The solubility constant of NpO 2 OH(am) has been reported a number of times for both zero ionic strength and in fixed ionic strength media. Americium can form four oxidation states in aqueous solution, namely trivalent, tetravalent, pentavalent and hexavalent. Desire, Hussonnois and Guillaumont determined stability constants for the species AmOH 2+ for the actinides, plutonium(III), americium(III), curium(III), berkelium(III) and californium(III) using a solvent extraction technique.

Recent progress in actinide and lanthanide solvent extraction

International Nuclear Information System (INIS)

Musikas, C.; Hubert, H.; Benjelloun, N.; Vitorge, P.; Bonnin, M.; Forchioni, A.; Chachaty, C.

1983-04-01

Work in progress on actinide solvent extraction is briefly reviewed in this paper. 1 H and 31 P NMR are used to elucidate several fundamental unsolved problems concerning organophosphorous extractants often used in actinides extraction: determination of site of dialkylthiophosphate protonation and addition of basic phosphine oxide to dibutylthiophosphoric acid dimer. Extraction of Am III and Eu from high radioactivity level wastes by tetrasubsituted methylene diamides is investigated. Trivalent actinide-lanthanide group are separated by solvent extraction using soft donor ligand complexes which are more stable. The synergism of dinonylnaphtalene sulfonic acid (HDNNS) associated with several neutral donors like TBP, TOPO, amides are examined in the trivalent and tetravalent actinide extraction

Solvation and complexation study by fluorescence spectroscopy of Eu(III) and Cm(III) ions in octanol solution and at the interface with water

International Nuclear Information System (INIS)

Vu, T.H.

2008-01-01

Polydentate N-donors ligands like bis-triazine-pyridine (BTP) and bis-triazine-bis-pyridine (BTBP) can selectively extract minor actinides (III) from lanthanides (III) ions and therefore have been studied in the field of nuclear waste reprocessing. The aim of the researches carried out during this thesis is a better description of this family in biphasic systems: speciation in the organic phase and around the interfacial area. After an exhaustive description of the solvation of europium(III) cation in mixed solutions n-octanol water with TRLIF spectrometry, the complexation with nitrogen ligands iPr-BTP, C5-BTBP and CyMe4-BTBP has been studied by TRLIF and ESI-MS techniques. For each compound, the inner sphere of europium has been described and the conditional stability constants determined. The composition of the organic medium, and particularly the hydration degree of n-octanol, has an impact on the nature and the ratio of species 'cation - counter ion - ligand - water'. With high water content (representative of extraction systems), the complexes observed with Cm(III) and Eu(III) have the same stoichiometry but the affinity towards the curium cation is higher and consistent to separation factors measured with biphasic systems. The method TIRF (total internal reflection fluorescence) was retained to study the behaviour of europium(III) inside the interfacial area. Fluorescence spectra of europium have been obtained but side signals and the high depth resolution of detection lead to difficulty in obtaining the signal of interfacial europium alone. The selected technique remains promising but some improvements need to be implemented for forthcoming measurement at liquid/liquid interface. (author) [fr

Synthesis and structural characterization of actinide oxalate compounds

International Nuclear Information System (INIS)

Tamain, C.

2011-01-01

Oxalic acid is a well-known reagent to recover actinides thanks to the very low solubility of An(IV) and An(III) oxalate compounds in acidic solution. Therefore, considering mixed-oxide fuel or considering minor actinides incorporation in ceramic fuel materials for transmutation, oxalic co-conversion is convenient to synthesize mixed oxalate compounds, precursors of oxide solid solutions. As the existing oxalate single crystal syntheses are not adaptable to the actinide-oxalate chemistry or to their manipulation constrains in gloves box, several original crystal growth methods were developed. They were first validate and optimized on lanthanides and uranium before the application to transuranium elements. The advanced investigations allow to better understand the syntheses and to define optimized chemical conditions to promote crystal growth. These new crystal growth methods were then applied to a large number of mixed An1(IV)-An2(III) or An1(IV)-An2(IV) systems and lead to the formation of the first original mixed An1(IV)-An2(III) and An1(IV)-An2(IV) oxalate single crystals. Finally thanks to the first thorough structural characterizations of these compounds, single crystal X-ray diffraction, EXAFS or micro-RAMAN, the particularly weak oxalate-actinide compounds structural database is enriched, which is essential for future studied nuclear fuel cycles. (author) [fr

A data base for thermodynamic modeling of +III actinide solubility in concentrated Na-Cl-SO4-CO3-PO4 electrolytes

International Nuclear Information System (INIS)

Novak, C.F.; Crafts, C.C.; Dhooge, N.J.

1995-01-01

The literature contains thermodynamic parameters for describing the chemical behavior of the following: Am(III) in dilute NaHCO 3 media; Nd(III) in dilute to concentrated Na 2 CO 3 and NaHCO 3 media; Pu(III) in dilute to concentrated NaCl media; Nd(III)/Am(III) in dilute to concentrated Na 2 SO 4 media; and Am(III) in NaH 2 PO 4 media. We have combined this information into a thermodynamic data base for the general +III actinide, An(III), using the analogy for chemical behavior of f-elements in the same oxidation state. This internally consistent data base is based on equilibrium thermodynamics and the specific ion interaction activity coefficient formalism of Pitzer. This data base forms the basis for the prediction of potential Am(III) and Pu(III) dissolved concentrations in the concentrated natural brines associated with the Waste Isolation Pilot Plant (WIPP) in Southeastern New Mexico, USA

NMR and TRLFS studies of Ln(iii) and An(iii) C5-BPP complexes† †Electronic supplementary information (ESI) available: LIFDI-MS spectra and additional NMR spectra. See DOI: 10.1039/c4sc03103b

Science.gov (United States)

Beele, Björn B.; Geist, Andreas; Müllich, Udo; Kaden, Peter; Panak, Petra J.

2015-01-01

C5-BPP is a highly efficient N-donor ligand for the separation of trivalent actinides, An(iii), from trivalent lanthanides, Ln(iii). The molecular origin of the selectivity of C5-BPP and many other N-donor ligands of the BTP-type is still not entirely understood. We present here the first NMR studies on C5-BPP Ln(iii) and An(iii) complexes. C5-BPP is synthesized with 10% 15N labeling and characterized by NMR and LIFDI-MS methods. 15N NMR spectroscopy gives a detailed insight into the bonding of C5-BPP with lanthanides and Am(iii) as a representative for trivalent actinide cations, revealing significant differences in 15N chemical shift for coordinating nitrogen atoms compared to Ln(iii) complexes. The temperature dependence of NMR chemical shifts observed for the Am(iii) complex indicates a weak paramagnetism. This as well as the observed large chemical shift for coordinating nitrogen atoms show that metal–ligand bonding in Am(C5-BPP)3 has a larger share of covalence than in lanthanide complexes, confirming earlier studies. The Am(C5-BPP)3 NMR sample is furthermore spiked with Cm(iii) and characterized by time-resolved laser fluorescence spectroscopy (TRLFS), yielding important information on the speciation of trace amounts of minor complex species. PMID:29560242

Molecular dynamics simulations of ter-pyridine and bis-triazinyl-pyridine complexes with lanthanide cations; Etude de dynamique moleculaire de complexes de la bis-triazinyl-pyridine (BTP) et de la terpyridine avec des lanthanides(3)

Energy Technology Data Exchange (ETDEWEB)

Guilbaud, Ph. [CEA Valrho, (DCC/DRRV/SEMP), 30 - Marcoule (France)

2000-07-01

The search for ligands which specifically separate actinides(III) from lanthanides(III) by liquid-liquid extraction has prompted considerable research in the Process Design and Modeling Department ('Service d'Etude et de Modelisation des Procedes'- SEMP). Ligands with soft donor atoms AS) that are able to perform this separation have already been investigated and research is currently under way to improve their performance for high acidic feeds. Theoretical chemistry research is conducted in the Theoretical and Structural Chemistry Laboratory ('Laboratoire de Chimie Theorique et Structurale') to improve our understanding of the complexation and extraction of these cations with such ligands. Theoretical studies were first carried out for the ter-pyridine (TPY) and bis-triazinyl-pyridine (BTP) ligands that display fairly good ability to separate and extract actinide(III) from lanthanide(III) ions. Molecular dynamics simulations were performed on ter-pyridine and bis-triazinyl-pyridine complexes with three lanthanide cations (La{sup 3+}, Eu{sup 3+} and Lu{sup 3+}) for vacuum and for water solutions. These calculations were carried out without counter-ions, with three nitrate (NO{sub 3}{sup -}) ions, and, in the case of ter-pyridine, with three {alpha}-bromo-caprate anions that are likely to be used experimentally as synergistic agents for the separation and extraction of An(III) from Ln(III). Molecular dynamics simulations were first performed for vacuum to evaluate the distances between nitrogen and lanthanide atoms (Ln{sup 3+},N) and intrinsic interaction energies to poly-nitrogenous ligands with or without NO{sub 3} ions, and for both ligands. The (Ln{sup 3+},N) distances decrease and the cation/ligand interaction energies increase along the La{sup 3+}, Eu{sup 3+}, Lu{sup 3+} series, with decreasing Ln(III) ion radii. The introduction of nitrate counter-ions makes the (Ln{sup 3+},N) distances slightly higher, and the TPY/Ln{sup 3+} and BTP

Research in actinide chemistry. Progress report, March 1, 1980-February 28, 1981

International Nuclear Information System (INIS)

1981-01-01

The primary purpose of this research is to study the behavior of actinide cations in aqueous solution. The interaction of trivalent actinides with a wide variety of both inorganic and organic ligands has been investigated with emphasis on the thermodynamics and kinetics of complexation at tracer concentrations using radiochemical techniques. In order to expand the scope of the experimental techniques, thereby obtaining additional understanding of the fundamental processes involved, non-radioactive experiments with the trivalent lanthanides have been conducted. Visible spectroscopy, nmr ( 1 1 H, 6 13 C, 57 139 La) spectroscopy, potentiometry, solvent extraction and calorimetry are examples of techniques for these lanthanide studies which have allowed much more thorough interpretation of the actinide tracer data due to the close chemical similarity of the lanthanide and actinide families of trivalent cations. The following were investigated: nmr shifts of 139 La for both halate and chloroacetate complexes; interaction of Pu(VI) with carbonates and bicarbonates; Ca +2 , UO 2 +2 , and Th +4 reactions with halate and chloroacetate anions; complexation of the lanthanides by benzoic acid; thermodynamic formation constants for trivalent lanthanide ions with succinic, glutaric, and adipic acids; complexation of benzene polycarboxylates with lanthanides; complexation of lanthanide ions by AMP (adenosine monophosphate), ADP (adenosine diphosphate) and ATP (adenosine triphosphate); interaction of the actinides ions with humic acid; measurements of water and benzoic acid concentrations in several organic solvents by potentiometric and spectral methods; and plutonium and neptunium redox behavior in the presence of organic complexing agents

Thermodynamic data for predicting concentrations of Pu(III), Am(III), and Cm(III) in geologic environments

Energy Technology Data Exchange (ETDEWEB)

Rai, Dhanpat; Rao, Linfeng; Weger, H.T.; Felmy, A.R. [Pacific Northwest National Laboratory, WA (United States); Choppin, G.R. [Florida State University, Florida (United States); Yui, Mikazu [Japan Nuclear Cycle Development Inst., Tokai Works, Tokai, Ibaraki (Japan)

1999-01-01

This report provides thermodynamic data for predicting concentrations of Pu(III), Am(III), and Cm(III) in geologic environments, and contributes to an integration of the JNC chemical thermodynamic database, JNC-TDB (previously PNC-TDB), for the performance analysis of geological isolation system for high-level radioactive wastes. Thermodynamic data for the formation of complexes or compounds with hydroxide, chloride, fluoride, carbonate, nitrate, sulfate and phosphate are discussed in this report. Where data for specific actinide(III) species are lacking, the data were selected based on chemical analogy to other trivalent actinides. In this study, the Pitzer ion-interaction model is mainly used to extrapolate thermodynamic constants to zero ionic strength at 25degC. (author)

Actinide extractants for the nuclear industry of the future

International Nuclear Information System (INIS)

Musikas, C.; Morisseau, J.C.; Hoel, P.; Guillaume, B.

1987-06-01

Non organo-phosphorus extractants properties regarding the extractions of actinides in nuclear fuels reprocessing are presented. N,N-dialkylamides are proposed as alternatives to TBP.N,N'-tetraalkylamides or pentaalkyl propane diamides properties are reported. They show that those bidentate extractants are alternatives to bidentate organophosphorus extractants for actinides (III) extraction from concentrated nitric acid. 11 figs, 15 refs

Seventeen-coordinate actinide helium complexes

Energy Technology Data Exchange (ETDEWEB)

Kaltsoyannis, Nikolas [School of Chemistry, The University of Manchester (United Kingdom)

2017-06-12

The geometries and electronic structures of molecular ions featuring He atoms complexed to actinide cations are explored computationally using density functional and coupled cluster theories. A new record coordination number is established, as AcHe{sub 17}{sup 3+}, ThHe{sub 17}{sup 4+}, and PaHe{sub 17}{sup 4+} are all found to be true geometric minima, with the He atoms clearly located in the first shell around the actinide. Analysis of AcHe{sub n}{sup 3+} (n=1-17) using the quantum theory of atoms in molecules (QTAIM) confirms these systems as having closed shell, charge-induced dipole bonding. Excellent correlations (R{sup 2}>0.95) are found between QTAIM metrics (bond critical point electron densities and delocalization indices) and the average Ac-He distances, and also with the incremental He binding energies. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

Investigation of the separation of americium(III) and europium(III) by high-speed countercurrent chromatography

International Nuclear Information System (INIS)

Wu, J.F.; Jin, Y.R.; Xu, Q.C.; Wang, S.L.; Zhang, L.X.

2005-01-01

The long-lived actinides are the important elements in the radioactive waste ;disposal. Because the ions semi diameter and chemical properties of trivalent actinides(III) and trivalent lanthanides(III) are very similar, the separation between them is very difficult. Yang Yu-Sheng put forward the actinides(III) are softer acid than the lanthanides(III), so the actinides(III) are more easily extracted by the soft extractant contain sulfur or nitrogen than the lanthanides(III). Some research have been done on the separation between actinides(III) and lanthanides(III) using the extractants contain sulfur or nitrogen. The results show that satisfactory separation efficiency was gained. Countercurrent Chromatography (CCC) have many specific advantages, such as free from solid support, permit large sample volume and high flow rate, which is useful in the preconcentration of inorganic solute and inorganic preparation. Some studies were done on the separation of lanthanides or-other inorganic elements by HSCCC, the high-purity reagents prepared by HSCCC or CPC turned out to be successful. In present paper, the investigation of separation between Americium (III) and Euricium (III) by High-Speed Countercurrent Chromatography (HSCCC) were made. The extractant used in the work was prepared by ourselves, which is of the soft extractant contrain sulfur. The effects of separation condition on the separation efficiency of Am and Eu by HSCCC were investigated using dichlorophenyl dithiophosphinic acid in xylene as the stationary phase and 0.1 mol/L NaClO4 as mobile phase, respectively. The results show that mutual separation between Am and Eu can be accomplished. The separation factor increases with the increasing of the concentration of extractant and the pH value of the mobile phase, further more, minishing the flow rate of the mobile phase can also improves the separation efficiency between Am and Eu. The nearly base separation was gained when the flow rate is 0.35 ml/min, the

Separation of lanthanides (III) and actinides (III) by calixarenes containing acetamide-phosphine oxides functions

International Nuclear Information System (INIS)

Garcia Carrera, A.; Dozol, J.F.; Rouquette, H.

2001-01-01

The carbamoyl methyl phosphine oxide CMPO is the well known extractant of the TRUEX process for extraction of actinides from highly salted acidic wastes. In the framework of an European research contract coordinated by CEA/DDCC. V. Boehmer (Mainz, Germany) synthesized calix(4)arenes bearing CMPO moieties either on the wide rim, or on the narrow rim. Some of these calixarenes used at a concentration 10 -3 M are more efficient than CMPO used at a two hundred fifty fold higher concentration. Moreover, calixarene skeleton leads to a strong selectivity among lanthanides, this selectivity is much less obvious for CMPO. Selectivity order is reversed according to whether CMPO unit is borne by the wide rim or the narrow rim. The most efficient calixarenes allow actinides to be separated from most of the lanthanides except the lightest ones. (authors)

Trivalent lanthanide/actinide separation in the spent nuclear fuel wastes' reprocessing

International Nuclear Information System (INIS)

Narbutt, J.; Krejzler, J.

2006-01-01

Separation of trivalent actinides, in particular americium and curium, from lanthanides is an important step in an advanced partitioning process for future reprocessing of spent nuclear fuels. Since the trivalent actinides and lanthanides have similar chemistries, it is rather difficult to separate them from each other. The aim of presented work was to study solvent extraction of Am(III) and Eu(III) in a system containing diethylhemi-BTP (6-(5,6-diethyl-1,2,4-triazin-3-yl)-2,2'-bipyridine) and COSAN (protonated bis(chlorodicarbollido)cobalt(III)). The system was chosen by several groups working in the integrated EC research Project EUROPART. Several physicochemical properties of the extraction system were analyzed and discussed

New insights into thorium and uranium oxo-arsenic (III/V) and oxo-phosphates (V) crystal chemistry

International Nuclear Information System (INIS)

Yu, Na

2015-01-01

The fundamental chemistry of actinides is of great interest owing to the diverse number of valence states and complex coordination chemistry of the actinides. The phases based on actinides and oxo-salt fragments have been under thorough investigation in the last decades. These compounds can be widely found in nature and they affect the migration process of actinides in nature. A better understanding of the fundamental coordination chemistry of actinide compounds with oxo-salts of group V elements is not only important for understanding the actinides behavior within the migration process but can also be used to understand actinide properties in phosphate ceramics. Concerning the radioactive issues, the less radioactive early actinides (i.e. U, Th) can be taken as modeling elements to study the crystal chemistry of the transuranic elements (Np, Pu) without the major handling problems. This can be done as Th(IV) has a very similar coordination chemistry with An(IV) and U(VI) can be chosen as a modeling element for transuranic elements in higher valence states. Therefore, a systematic research on the actinides (U, Th) bearing phases with tetrahedral oxo-anions such as phosphates and arsenates have been performed in this work. High temperature (HT) solid state reaction, High pressure high temperature (HP-HT) solid state reaction and the hydrothermal method were the methods of choice for synthesizing actinide bearing oxo-arsenic(III/V) and oxo- phosphorus(V) phases in the past three years. As a result, numerous novel compounds containing actinides were obtained. The structures of all compounds were determined using single crystal X-ray diffraction data. Raman spectroscopy, EDS, DSC and high temperature powder X-ray diffraction (HT-PXRD) measurements were implemented to characterize the chemical and physical properties of the obtained compounds. The core of this dissertation is a fundamental study of the crystal chemistry of actinides (Th, U) oxo-arsenic (III/V) and oxo

Complexation of Eu(III) with a polymeric cement additive as a potential carrier of actinides

Energy Technology Data Exchange (ETDEWEB)

Lippold, Holger; Becker, Michael [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Reactive Transport

2017-06-01

In the long term, cementitious materials in a final repository will be exposed to leaching processes generating highly alkaline solutions. Polymeric additives, so-called superplasticizers, are considered as potential mobilizing agents for released radionuclides, since it is uncertain whether complete degradation will take place under the evolving aqueous conditions. Regarding the complexing properties of superplasticizers, there are only indirect assessments so far. In this study, first systematic investigations on complexation with Eu(III) as an analogue of trivalent actinides were performed at variable pH and electrolyte content (NaCl, CaCl{sub 2}) using ultrafiltration as a separation method. A stability constant was derived according to the charge neutralization model. For this purpose, the proton exchange capacity was determined by potentiometric titration.

Rapid ion-exchange separations of actinides

International Nuclear Information System (INIS)

Usuda, Shigekazu

1988-01-01

For the purpose of studying short-lived actinide nuclides, three methods for rapid ion exchange separation of actinide elements with mineral acid-alcohol mixed media were developed: anion exchange with nitric acid-methyl alcohol mixed media to separate the transplutonium and rare earth elements from target material, U or Pu and Al catcher foils; anion exchange with hydrochloric acid-methyl alcohol media to separate Am+Cm, Bk and Cf+Fm from the target, catcher foils and major fission products; and cation exchange with hydrochloric acid-methyl alcohol media and with concentrated hydrochloric acid to separate the transplutonium elements as a group from the rare earths after eliminating the large amounts of U, Al, Cu, Fe etc. The methods enable one to perform rapid and effective separation at elevated temperature (90 deg C) and immediate source preparation for alpha-ray spectrometry. (author) 47 refs.; 10 figs

Actinide speciation in the environment

International Nuclear Information System (INIS)

Choppin, G.R.

2007-01-01

Nuclear test explosions and nuclear reactor wastes and accidents have released large amounts of radioactivity into the environment. Actinide ions in waters often are not in a state of thermodynamic equilibrium and their solubility and migration behavior is related to the form in which the nuclides are introduced into the aquatic system. Chemical speciation, oxidation state, redox reactions, and sorption characteristics are necessary in predicting solubility of the different actinides, their migration behaviors and their potential effects on marine biota. The most significant of these variables is the oxidation state of the metal ion as the simultaneous presence of more than one oxidation state for some actinides in a solution complicates actinide environmental behavior. Both Np(V)O 2 + and Pu(V)O 2 + , the most significant soluble states in natural oxic waters, are relatively noncomplexing and resistant to hydrolysis and subsequent precipitation. The solubility of NpO 2 + can be as high as 10 -4 M while that of PuO 2 + is much more limited by reduction to the insoluble tetravalent species, Pu(OH) 4 , (pK sp ≥56) but which can be present in the pentavalent form in aqautic phases as colloidal material. The solubility of hexavalent UO 2 2+ in sea water is relatively high due to formation of carbonate complexes. The insoluble trivalent americium hydroxocarbonate, Am(OH)(CO 3 ) is the limiting species for the solubility of Am(III) in sea water. Thorium(IV) is present as Th(OH) 4 , in colloidal form. The chemistry of actinide ions in the environment is reviewed to show the spectrum of reactions that can occur in natural waters which must be considered in assessing the environmental behavior of actinides. Much is understood about sorption of actinides on surfaces, the mode of migration of actinides in such waters and the potential effects of these radioactive species on marine biota, but much more understanding of the behavior of the actinides in the environment is

The structure of actinide ions exchanged into native and modified zeolites and clays

International Nuclear Information System (INIS)

Wasserman, S. R.; Soderholm, L.; Giaquinta, D. M.

2000-01-01

X-ray absorption spectroscopy (XAS) has been used to investigate the structure and valence of thorium (Th 4+ ) and uranyl (UO 2 2+ ) cations exchanged into two classes of microporous aluminosilicate minerals: zeolites and smectite clays. XAS is also employed to examine the fate of the exchanged cations after modification of the mineral surface using self-assembled organic films and/or exposure to hydrothermal conditions. These treatments serve as models for the forces that ultimately determine the chemical fate of the actinide cations in the environment. The speciation of the cations depends on the pore size of the aluminosilicate, which is fixed for the zeolites and variable for the smectites

Uranium (III)-Plutonium (III) co-precipitation in molten chloride

Science.gov (United States)

Vigier, Jean-François; Laplace, Annabelle; Renard, Catherine; Miguirditchian, Manuel; Abraham, Francis

2018-02-01

Co-management of the actinides in an integrated closed fuel cycle by a pyrochemical process is studied at the laboratory scale in France in the CEA-ATALANTE facility. In this context the co-precipitation of U(III) and Pu(III) by wet argon sparging in LiCl-CaCl2 (30-70 mol%) molten salt at 705 °C is studied. Pu(III) is prepared in situ in the molten salt by carbochlorination of PuO2 and U(III) is then introduced as UCl3 after chlorine purge by argon to avoid any oxidation of uranium up to U(VI) by Cl2. The oxide conversion yield through wet argon sparging is quantitative. However, the preferential oxidation of U(III) in comparison to Pu(III) is responsible for a successive conversion of the two actinides, giving a mixture of UO2 and PuO2 oxides. Surprisingly, the conversion of sole Pu(III) in the same conditions leads to a mixture of PuO2 and PuOCl, characteristic of a partial oxidation of Pu(III) to Pu(IV). This is in contrast with coconversion of U(III)-Pu(III) mixtures but in agreement with the conversion of Ce(III).

Titanium (III) cation selective electrode based on synthesized tris(2pyridyl) methylamine ionophore and its application in water samples

Science.gov (United States)

Rezayi, Majid; Karazhian, Reza; Abdollahi, Yadollah; Narimani, Leila; Sany, Seyedeh Belin Tavakoly; Ahmadzadeh, Saeid; Alias, Yatimah

2014-04-01

The introduction of low detection limit ion selective electrodes (ISEs) may well pave the way for the determination of trace targets of cationic compounds. This research focuses on the detection of titanium (III) cation using a new PVC-membrane sensor based on synthesized tris(2pyridyl) methylamine (tpm) ionophore. The application and validation of the proposed sensor was done using potentiometric titration, inductively coupled plasma atomic emission spectrometry (ICP-AES), and atomic absorption spectrometry (AAS). The membrane sensor exhibited a Nernstian response to the titanium (III) cation over a concentration range of 1.0 × 10-6-1.0 × 10-2 M and pH range from 1-2.5. The Nernstian slope, the lower of detection (LOD), and the response time (t95%) of the proposed sensor were 29.17 +/- 0.24 mV/dec, 7.9 × 10-7 M, and 20 s, respectively. The direct determination of 4-39 μg/ml of titanium (III) standard solution showed an average recovery of 94.60 and a mean relative standard deviation of 1.8 at 100.0 μg/ml. Finally, the utilization of the electrodes as end-point indicators for potentiometric titration with EDTA solutions for titanium (III) sensor was successfully carried out.

Synthesis and characterisation of nitrogen-containing poly heterocyclic molecules for the complexation of polluting metal cations; Synthese et caracterisation de molecules polyheterocycliques azotees pour la complexation de cations metalliques polluants

Energy Technology Data Exchange (ETDEWEB)

Leconte, N

2007-12-15

The recovery of actinides(III) from the mixture actinides(III)/lanthanides(III) is a great deal of the nuclear waste management. Experiences have shown that derivatives of 2,6- bis(1,2,4-triazine-3-yl)pyridine (BTP) are able to extract selectively actinides(III) from lanthanides(III). But the properties of these molecules need to be reinforced to exhibit best extraction performances and to resist to the harsh conditions of the extracting processes. Originally functionalized ligands were synthesized and tested in a radioactive medium. In a second part, this work focuses on the control and the detection of actinides(III). This could be done thanks to the use of a chemical sensor such as quartz crystal microbalance. The study of this apparatus required the preliminary synthesis of original complexing BTP-derived structures. The last part of this work deals with the study of new synthetic ways to afford the BTP moiety. The palladium-catalyzed cross-coupling reaction of 3-methylthio-1,2,4-triazine with various 2-stannylated pyridines have been explored. Our investigations have also allowed to develop a method for synthesizing unsymmetrical 1,2,4,5-tetrazine from the cross-coupling reaction between 3-methylthio-6-(morpholine-N-yl)-1,2,4,5-tetrazine and organoboron / organo-stannane derivatives. (author)

Angular overlap model in actinides

International Nuclear Information System (INIS)

Gajek, Z.; Mulak, J.

1991-01-01

Quantitative foundations of the Angular Overlap Model in actinides based on ab initio calculations of the crystal field effect in the uranium (III) (IV) and (V) ions in various crystals are presented. The calculations justify some common simplifications of the model and fix up the relations between the AOM parameters. Traps and limitations of the AOM phenomenology are discussed

Angular overlap model in actinides

Energy Technology Data Exchange (ETDEWEB)

Gajek, Z.; Mulak, J. (Polska Akademia Nauk, Wroclaw (PL). Inst. Niskich Temperatur i Badan Strukturalnych)

1991-01-01

Quantitative foundations of the Angular Overlap Model in actinides based on ab initio calculations of the crystal field effect in the uranium (III) (IV) and (V) ions in various crystals are presented. The calculations justify some common simplifications of the model and fix up the relations between the AOM parameters. Traps and limitations of the AOM phenomenology are discussed.

Interaction of selected actinides (U, Cm) with bacteria relevant to nuclear waste disposal

Energy Technology Data Exchange (ETDEWEB)

Luetke, Laura

2013-07-01

To assess the safety of a site destined for storage of nuclear waste enhanced research effort is demanded to investigate the complex interactions of released radionuclides with parts of the environment that includes indigenous microorganisms. This work aimed at assessing the interactions of two bacterial strains with the actinides uranium and curium with a focus on thermodynamics to provide stability constants of the actinide bacteria species formed usable for modelling the distribution of these actinides in the environment. The influences of Pseudomonas fluorescens (CCUG 32456A) isolated from the granitic aquifers at Aespoe(Sweden) and a novel isolate from Mont Terri Opalinus clay (Switzerland), Paenibacillus sp. MT-2.2, were investigated. A combined approach using microbiological and spectroscopic techniques as well as potentiometry was employed to characterize the U(VI) and Cm(III) binding onto the cell surface functional groups structurally and thermodynamically. Further, due to its similar ionic radius to Cm(III) also Eu(III) was studied as non-radioactive analog.

Recovery of actinides from actinide-aluminium alloys by chlorination: Part III - Chlorination with HCl(g)

Science.gov (United States)

Meier, Roland; Souček, Pavel; Walter, Olaf; Malmbeck, Rikard; Rodrigues, Alcide; Glatz, Jean-Paul; Fanghänel, Thomas

2018-01-01

Two steps of a pyrochemical route for the recovery of actinides from spent metallic nuclear fuel are being investigated at JRC-Karlsruhe. The first step consists in electrorefining the fuel in molten salt medium implying aluminium cathodes. The second step is a chlorination process for the separation of actinides (An) from An-Al alloys formed on the cathodes. The chlorination process, in turn, consists of three steps; the distillation of adhered salt (1), the chlorination of An-Al by HCl/Cl2 under formation of AlCl3 and An chlorides (2), and the subsequent sublimation of AlCl3 (3). In the present work UAl2, UAl3, NpAl2, and PuAl2 were chlorinated with HCl(g) in a temperature range between 300 and 400 °C forming UCl4, NpCl4 or PuCl3 as the major An containing phases, respectively. Thermodynamic calculations were carried out to support the experimental work. The results showed a high chlorination efficiency for all used starting materials and indicated that the sublimation step may not be necessary when using HCl(g).

2-(2′-Pyridyl)-4,6-diphenylphosphinine versus 2-(2′-Pyridyl)-4,6-diphenylpyridine: Synthesis, Characterization, and Reactivity of Cationic RhIII and IrIII Complexes Based on Aromatic Phosphorus Heterocycles

NARCIS (Netherlands)

de Krom, I.; Broeckx, L.E.E.; Lutz, M.; Müller, Christian

2013-01-01

The bidentate P,N hybrid ligand 1 allows access for the first time to novel cationic phosphinine-based RhIII and IrIII complexes, broadening significantly the scope of low-coordinate aromatic phosphorus heterocycles for potential applications. The coordination chemistry of 1 towards RhIII and IrIII

Adsorption of Cr(III) on ozonised activated carbon. Importance of Cpi-cation interactions.

Science.gov (United States)

Rivera-Utrilla, J; Sánchez-Polo, M

2003-08-01

The adsorption of Cr(III) in aqueous solution was investigated on a series of ozonised activated carbons, analysing the effect of oxygenated surface groups on the adsorption process. A study was carried out to determine the adsorption isotherms and the influence of the pH on the adsorption of this metal. The adsorption capacity and affinity of the adsorbent for Cr(III) increased with the increase in oxygenated acid groups on the surface of the activated carbon. These findings imply that electrostatic-type interactions predominate in the adsorption process, although the adsorption of Cr(III) on the original (basic) carbon indicates that other forces also participate in the adsorption process. Thus, the ionic exchange of protons in the -Cpi-H3O(+) interaction for Cr(III) accounts for the adsorption of cationic species in basic carbons with positive charge density. Study of the influence of pH on the adsorption of Cr(III) showed that, in each system, the maximum adsorption occurred when the charge of the carbon surface was opposite that of the species of Cr(III) present at the pH of the experiment. These results confirmed that electrostatic interactions predominate in the adsorption process.

Coordination chemistry of several radius-sensitive complexones and applications to lanthanide-actinide separations

Energy Technology Data Exchange (ETDEWEB)

Potter, M.W.

1981-10-01

The relationships between the lanthanide complex formation equilibria and the lanthanide-actinide separation application of three radius sensitive ligands have been studied. The consecutive stepwise formation constants of the 1:1, 2:1, and 3:1 chelate species formed by the interaction of DHDMB and the tripositive lanthanides and yttrium were determined potentiometrically at 0.1 M ionic strength and 25/sup 0/C. Results indicate that three different coordination modes, one tridentate and two bidentate are in evidence. Tracer level /sup 241/Am - /sup 155/Eu cation-exchange experiments utilizing DHDMB eluents indicate that this dihydroxycarboxylate does not form a sufficiently strong americium complex to elute that actinide ahead of europium. The overall stability of the americium 3:1 complex appears intermediate between samarium and europium. Cation-exchange elutions of /sup 241/Am, /sup 155/Eu, and /sup 160/Tb mixtures with EEDTA solutions prove that the EEDTA ligand is capable of eluting americium ahead of all of the tripositive lanthanide cations. The minimum separation occurs with terbium, where the Am-Tb separation factor is 1.71. 1,5-diaminopentane-N,N,N',N'-tetraacetic acid (PMDTA) was synthesized using cation exchange. A mathematical method was developed for the formation constants of the protonated and unprotonated lanthanide-PMDTA complexes from potentiometry. Cation-exchange elutions of tracer quantities of Am, Eu, and Tb revealed that terbium is eluted ahead of both americium and europium.

Minor actinide transmutation using minor actinide burner reactors

International Nuclear Information System (INIS)

Mukaiyama, T.; Yoshida, H.; Gunji, Y.

1991-01-01

The concept of minor actinide burner reactor is proposed as an efficient way to transmute long-lived minor actinides in order to ease the burden of high-level radioactive waste disposal problem. Conceptual design study of minor actinide burner reactors was performed to obtain a reactor model with very hard neutron spectrum and very high neutron flux in which minor actinides can be fissioned efficiently. Two models of burner reactors were obtained, one with metal fuel core and the other with particle fuel core. Minor actinide transmutation by the actinide burner reactors is compared with that by power reactors from both the reactor physics and fuel cycle facilities view point. (author)

Reversible optical sensor for the analysis of actinides in solution

International Nuclear Information System (INIS)

Lesage, B.; Picard, S.; Serein-Spirau, F.; Lereporte, J.P.

2007-01-01

In this work is presented a concept of reversible optical sensor for actinides. It is composed of a p doped conducing polymer support and of an anion complexing the actinides. The chosen conducing polymer is the thiophene-2,5-di-alkoxy-benzene whose solubility and conductivity are perfectly known. The actinides selective ligand is a lacunar poly-oxo-metallate such as P 2 W 17 O 61 10- or SiW 11 O 39 8- which are strong anionic complexing agents of actinides at the oxidation state (IV) even in a very acid medium. The sensor is prepared by spin coating of the composite mixture 'polymer + ligand' on a conducing glass electrode and then tested towards its optical and electrochemical answer in presence of uranium (IV). The absorption change due to the formation of cations complexes by poly-oxo-metallate reveals the presence of uranium (IV). After the measurement, the sensor is regenerated by anodic polarization of the support and oxidation of the uranium (IV) into uranium (VI) which weakly interacts with the poly-oxo-metallate and is then released in solution. (O.M.)

'Americium(III)/trivalent lanthanides' separation using organothiophosphinic acids

International Nuclear Information System (INIS)

Hill, C.; Madic, C.; Baron, P.; Ozawa, Masaki; Tanaka, Yasumasa.

1997-01-01

The present paper describes the extraction of neodymium and other lanthanides by saponified Cyanex 301 acid. The saponification of commercial Cyanex 301 acid favoured the extraction of macro concentrations of neodymium from sodium nitrate aqueous solutions (pH eq ∼ 4). The amount of lanthanide extracted in the organic phase always reached the third of the initial concentration of saponified Cyanex 301 acid, which assumed a cation exchange mechanism to occur during the extraction. No nitrate anion took part in the complex formation. This paper also compares the abilities of purified Cyanex 301, Cyanex 302 and Cyanex 272 acids to extract and separate 241 Am(III) from 152 Eu(III). Very high separation factors S.F. Am/Eu were observed in the case of purified Cyanex 301 acid. Finally some studies are presented herein using tri-n-butylphosphate (TBP) as a synergistic extractant with Cyanex 301 acid to separate actinides from trivalent lanthanide. (author)

Use of Electro-spray Ionization Mass Spectrometry (ESI-MS) for the characterization of complexes 'ligand - metallic cations' in solution

Energy Technology Data Exchange (ETDEWEB)

Berthon, Laurence; Zorz, Nicole; Lagrave, Stephanie; Gannaz, Benoit; Hill, Clement [CEA-Marcoule DEN-DRCP-SCPS-LCSE, BP 17171, 30207 Bagnols sur Ceze cedex (France)

2008-07-01

In the framework of nuclear waste reprocessing, separation processes of minor actinides from fission products are developed by Cea. In order to understand the mechanisms involved in the extraction processes, the 'ligand/metallic cation' complexes, formed in the organic phases are characterized by electro-spray-mass-spectrometry (ESI-MS). This paper deals with the extraction of lanthanides (III) and americium (III) cations by an organic phase composed of a malonamide or / and a dialkyl phosphoric acid, diluted in an aliphatic diluent. For the dialkyl phosphoric acid, Ln(DEHP){sub 3}(HDEHP){sub 3} complexes are observed and in the presence of a large excess of Ln(NO{sub 3}){sub 3}, dinuclear species are also observed. For the malonamide extractant, it appears that the complexes formed in the organic phase are of the Nd(NO{sub 3}){sub 3}D{sub x} type, with 2 {<=} x {<=} 4: their distributions depend on the ratio [Ln]/[DMDOHEMA]. When the two extractants are present in the organic phase, mixed 'Ln-malonamide-dialkyl phosphoric acid' species are observed. The influence of several parameters, such as extractant concentration, solute concentration, aqueous acidity and the nature of the cations (lanthanides or americium) are studied. (authors)

Pentachlorophenol radical cations generated on Fe(III)-montmorillonite initiate octachlorodibenzo-p-dioxin formation in clays: DFT and FTIR studies

Science.gov (United States)

Gu, Cheng; Liu, Cun; Johnston, Cliff T.; Teppen, Brian J.; Li, Hui; Boyd, Stephen A.

2011-01-01

Octachlorodibenzodioxin (OCDD) forms spontaneously from pentachlorophenol (PCP) on the surfaces of Fe(III)-saturated smectite clay (1). Here, we used in situ FTIR methods and quantum mechanical calculations to determine the mechanism by which this reaction is initiated. As the clay was dehydrated, vibrational spectra showed new peaks that grew and then reversibly disappeared as the clay rehydrated. First principle DFT calculations of hydrated Fe-PCP clusters reproduced these transient FTIR peaks when inner-sphere complexation and concomitant electron transfer produced Fe(II) and PCP radical cations. Thus, our experimental (FTIR) and theoretical (quantum mechanical) results mutually support the hypothesis that OCDD formation on Fe-smectite surfaces is initiated by the reversible formation of metastable PCP radical cations via single electron transfer from PCP to Fe(III). The negatively charged clay surface apparently selects for this reaction mechanism by stabilizing PCP radical cations. PMID:21254769

Review of the sorption of actinides on natural minerals

International Nuclear Information System (INIS)

Beall, G.W.

1981-01-01

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

Actinide immobilization in the subsurface environment by in-situ treatment with a hydrolytically unstable organophosphorus complexant: Uranyl uptake by calcium phytate

International Nuclear Information System (INIS)

Nash, K.L.; Jensen, M.P.; Schmidt, M.A.

1997-01-01

In addition to naturally occurring uranium and thorium, actinide ions exist in the subsurface environment as a result of accidental releases and intentional disposal practices associated with nuclear weapons production. These species present a significant challenge to cost-effective remediation of contaminated environments. An attractive approach to decreasing the probability of actinide migration in the subsurface is to transform the ions into a less mobile form by remote treatment. We have under development a process which relies on a polyfunctional organophosphorus complexant to sequester the mobile metal ions by complexation/cation exchange in the near term, and to subsequently decompose, transforming the actinides into insoluble phosphate mineral forms in the long term. Studies to date include identification of a suitable organophosphorus reagent, profiling of its decomposition kinetics, verification of the formation of phosphate mineral phases upon decomposition of the reagent, and extensive comparison of the actinide uptake ability of the calcium salt of the reagent as compared with hydroxyapatite. In this report, we briefly describe the process with focus on the cation exchange behavior of the calcium salt of the organophosphorus sequestrant

New insights into thorium and uranium oxo-arsenic (III/V) and oxo-phosphates (V) crystal chemistry

Energy Technology Data Exchange (ETDEWEB)

Yu, Na

2015-12-11

The fundamental chemistry of actinides is of great interest owing to the diverse number of valence states and complex coordination chemistry of the actinides. The phases based on actinides and oxo-salt fragments have been under thorough investigation in the last decades. These compounds can be widely found in nature and they affect the migration process of actinides in nature. A better understanding of the fundamental coordination chemistry of actinide compounds with oxo-salts of group V elements is not only important for understanding the actinides behavior within the migration process but can also be used to understand actinide properties in phosphate ceramics. Concerning the radioactive issues, the less radioactive early actinides (i.e. U, Th) can be taken as modeling elements to study the crystal chemistry of the transuranic elements (Np, Pu) without the major handling problems. This can be done as Th(IV) has a very similar coordination chemistry with An(IV) and U(VI) can be chosen as a modeling element for transuranic elements in higher valence states. Therefore, a systematic research on the actinides (U, Th) bearing phases with tetrahedral oxo-anions such as phosphates and arsenates have been performed in this work. High temperature (HT) solid state reaction, High pressure high temperature (HP-HT) solid state reaction and the hydrothermal method were the methods of choice for synthesizing actinide bearing oxo-arsenic(III/V) and oxo- phosphorus(V) phases in the past three years. As a result, numerous novel compounds containing actinides were obtained. The structures of all compounds were determined using single crystal X-ray diffraction data. Raman spectroscopy, EDS, DSC and high temperature powder X-ray diffraction (HT-PXRD) measurements were implemented to characterize the chemical and physical properties of the obtained compounds. The core of this dissertation is a fundamental study of the crystal chemistry of actinides (Th, U) oxo-arsenic (III/V) and oxo

Synthesis and evaluation structure/extracting and complexing properties of new bi-topic ligands for group actinides extraction

International Nuclear Information System (INIS)

Bisson, J.

2011-01-01

The aim of this project is to design and study new extractants for spent nuclear fuel reprocessing. To decrease the long-term radiotoxicity of the waste, the GANEX process is an option to homogeneously recycle actinides. All actinides (U, Np, Pu, Am, Cm) would be extracted together from a highly acidic media and separated from fission products (especially from lanthanides). In this context, fourteen new bi-topic ligands constituted of a nitrogen poly-aromatic unit from the dipyridyl-phenanthroline and dipyridyl-1,3,5-triazine families and functionalized by amid groups were synthesized. Extraction studies performed with some of these ligands confirmed their interest to selectively separate actinides at different oxidation states from an aqueous solution 3M HNO 3 . To determine the influence of ligands structure on cation complexation, a study in a homogenous media (MeOH/H 2 O) has been carried out. Electro-spray ionization mass spectrometry have been used to characterize the complexes stoichiometries formed with several cations (Eu 3+ , Nd 3+ , Am 3+ , Pu 4+ and NpO 2 + ). Stability constants, evaluated by UV-Visible spectrophotometry, confirm the selectivity of these ligands toward actinides. Lanthanides and actinides complexes have also been characterized in the solid state by infra-red spectroscopy and X-Ray diffraction. Associated to nuclear magnetic resonance experiments and DFT calculations (Density Functional Theory), a better knowledge of their coordination mode was achieved. (author) [fr

Lanthanides(3)/ actinides (3) separation by nano-filtration-complexation in aqueous medium

International Nuclear Information System (INIS)

Chitry, F.; Pellet-Rostaing, S.; Gozzi, C.; Lemaire, M.; Guy, A.; Foos, J.

2000-01-01

Lanthanides(III)/actinides(III) separation is a major research subject in matter of treatment of high activity liquid effluents. Liquid-liquid extraction actually gives the best results for this separation. In order to demonstrate that nano-filtration (NF) is a valuable alternative to liquid-liquid extraction, we tried to separate different lanthanides(III) with a nano-filtration process combined with a selective complexation step. At first DTPA (diethylene-triamine-pentaacetic acid) combined with a Sepa MG-17 (Osmonics) gave a 95% retention of Gd 3+ and a 50% retention of La 3+ . Then new hydrosoluble and more selective ligands derived from DTPA were synthesized. One of them combined with a Sepa MG-17 membrane allowed a 87% retention of Gd 3+ and a 5% retention of La 3+ . The same nano-filtration-complexation system was experimented with an equimolar aqueous solution of Gd 3+ , Pr 3+ and La 3+ . Other experiments in the field of actinides(III)/lanthanides(III) separation were also performed. (authors)

Partnew - New solvent extraction processes for minor actinides - final report; Partnew - Nouveaux procedes d'extraction par solvant pour les actinides mineurs - rapport final

Energy Technology Data Exchange (ETDEWEB)

Madic, C.; Testard, F.; Hudson, M.J.; Liljenzin, J.O.; Christiansen, B.; Ferrando, M.; Facchini, A.; Geist, A.; Modolo, G.; Gonzalez-Espartero, A.; Mendoza, J. de

2004-07-01

The objectives of the European project PARTNEW were to define solvent extraction processes for the partitioning of the minor actinides, Am and Cm, from the aqueous high active raffinate or high active concentrate issuing the reprocessing of nuclear spent fuels by the PUREX process. Eleven laboratories participated to the research: 1/ CEA-DEN (Marcoule), 2/ CEA-DSM (Saclay), 3/ UREAD (U.K.), 4/ CTU (Sweden), 5/ ITU (Germany), 6/ ENEA (Italy), 7/ PoliMi (Italy), 8/ FZK-INE (Germany), 9/ FZJ-ISR (Germany), 10/ CIEMAT (Spain) and 11/ UAM (Spain). The research was organised into eight work packages (WP): Basic and applied DIAMEX studies, using diamide extractants for the co-extraction of actinides(III) (An(III)) and lanthanides(III) (Ln(III)) nitrates (WP1 and WP2), Basic and applied SANEX studies based on the use of polydentate N-ligands for the An(III)/Ln(III) separation (WP3 and WP4), Basic and applied SANEX studies based on the use of synergistic mixtures made of bis-(chloro-phenyl)-di-thio-phosphinic acid + neutral O-bearing ligand, (WP5 and WP6), Basic SANEX studies for the An(III)/Ln(III) separation, based on the use of new S-bearing ligands, Basic and applied studies for the Am(III)/Cm(III) separation. The work done in the fundamental and applied domains was very fruitful. Several processes have been successfully tested with genuine high active raffinates and concentrate. (authors)

Molecular and supramolecular speciations of solvent extraction systems based on malonamide and/or dialkyl-phosphoric acids for An(III)/Ln(III); Speciations moleculaire et supramoleculaire de systemes d'extraction liquide-liquide a base de malonamide et/ou d'acides dialkylphosphoriques pour la separation An(III)/Ln(III)

Energy Technology Data Exchange (ETDEWEB)

Gannaz, B

2006-06-15

The solvent extraction system used in the DIAMEX-SANEX process, developed for the actinide(III)/lanthanide(III) separation, is based on the use of mixtures of the malonamide DMDOHEMA and a dialkyl-phosphoric acid (HDEHP or HDHP), in hydrogenated tetra-propylene. The complexity of these systems urges on a novel approach to improve the conventional methods (thermodynamics, solvent extraction) which hardly explain the macroscopic behaviors observed (3. phase, over-stoichiometry). This approach combines studies on both supramolecular (VPO, SANS, SAXS) and molecular (liquid-liquid extraction, ESI-MS, IR, EXAFS) speciations of single extractant systems (DMDOHEMA or HDHP in in n-dodecane) and their mixture. In spite of safety constraints due to the handling of radio-material, they were used in the studies as much as possible, like for SAXS measurements on americium-containing samples, a worldwide first-time. In each of the investigated systems, actinides(III) and lanthanides(III) are extracted to the organic phase in polar cores of reversed micelles, the inner and outer-sphere compositions of which are proposed. Thus, the 4f and 5f cations are extracted by reversed micelles such as [(DMDOHEMA){sub 2}M(NO{sub 3}){sub 3}]{sub inn} (DMDOHEMA){sub x}(HNO{sub 3}){sub z}(H{sub 2}O){sub w}]{sub out} and M(DHP){sub 3}(HDHP){sub y-3}(H{sub 2}O){sub w} with y = 3 to 6, for the single extractant systems. In the case of the two extractants system, the less concentrated one acts like a co-surfactant regarding the mixed aggregate formation [(DMDOHEMA){sub 2}M(NO{sub 3}){sub 3-v}(DHP){sub v}]{sub inn} [(DMDOFIEMA){sub x}(HDHP){sub y}(HNO{sub 3})z(H{sub 2}O){sub w}]{sub out}. (author)

Sequestering agents for the removal of actinides from waste streams

Energy Technology Data Exchange (ETDEWEB)

Raymond, K.N.; White, D.J.; Xu, Jide; Mohs, T.R. [Univ. of California, Berkeley, CA (United States)

1997-10-01

The goal of this project is to take a biomimetic approach toward developing new separation technologies for the removal of radioactive elements from contaminated DOE sites. To achieve this objective, the authors are investigating the fundamental chemistry of naturally occurring, highly specific metal ion sequestering agents and developing them into liquid/liquid and solid supported actinide extraction agents. Nature produces sideophores (e.g., Enterobactin and Desferrioxamine B) to selectivity sequester Lewis acidic metal ions, in particular Fe(III), from its surroundings. These chelating agents typically use multiple catechols or hydroxamic acids to form polydentate ligands that chelate the metal ion forming very stable complexes. The authors are investigating and developing analogous molecules into selective chelators targeting actinide(IV) ions, which display similar properties to Fe(III). By taking advantage of differences in charge, preferred coordination number, and pH stability range, the transition from nature to actinide sequestering agents has been applied to the development of new and highly selective actinide extraction technologies. Additionally, the authors have shown that these chelating ligands are versatile ligands for chelating U(VI). In particular, they have been studying their coordination chemistry and fundamental interactions with the uranyl ion [UO{sub 2}]{sup 2+}, the dominant form of uranium found in aqueous media. With an understanding of this chemistry, and results obtained from in vivo uranium sequestration studies, it should be possible to apply these actinide(IV) extraction technologies to the development of new extraction agents for the removal of uranium from waste streams.

Local Structure in Americium and Californium Hexa-cyanoferrates - Comparison with Their Lanthanide Analogues

International Nuclear Information System (INIS)

Dupouy, G.; Bonhoure, I.; Dumas, Th.; Moisy, Ph.; Petit, S.; Den Auwer, Ch.; Conradson, St.D.; Hennig, Ch.; Scheinost, A.C.; Le Naour, C.; Simoni, E.

2011-01-01

Metal hexa-cyanoferrates are well known molecular solids for a large variety of cations, although very little has been described for actinide adducts. Two new members of actinide(III) hexa-cyanoferrates were synthesized with the cations americium and californium. They were structurally characterized by infrared and X-ray absorption spectroscopy. Combined EXAFS data at the iron K edge and actinide L 3 edge provide evidence for a three-dimensional model for these two new compounds. Structural data in terms of bond lengths were compared to those reported for the parent lanthanide(III) compounds, neodymium and gadolinium hexa-cyanoferrates, respectively: the americium compound with (KNd(III)Fe(II)-Fe-III(CN) 6 .4H 2 O and the californium compound with (KGd(III)Fe(II)(CN) . 3.5H 2 O and (KGd(III)Fe(II)(CN) 6 .3H 2 O. This comparison between actinide and lanthanide homologues has been carried out on the basis of ionic radii considerations. The americium and neodymium environments appear to be very similar and are arranged in a tri-capped trigonal prism polyhedron of coordination number 9 (CN: 9), in which the americium atom is bonded to six nitrogen atoms and to three water molecules. For the californium adduct, a similar comparison and bond length and angle values derived from EXAFS studies suggest that the californium cation sits in a bi-capped trigonal prism (CN: 8) as in (KGd(III)Fe(II)(CN) 6 . 3H 2 O. This arrangement differs from that in the structure of (KGd(III)Fe(II)(CN) 6 .3.5H 2 O, in which the gadolinium atom is surrounded by 9 atoms. This is one of the rare pieces of information revealed by EXAFS spectroscopy for americium and californium in comparison to lanthanide atoms in molecular solid compounds. A discussion on the decrease in bond length and coordination number from americium to californium is also provided, on the basis of crystallographic results reported in the literature for actinide(III) and lanthanide(III) hydrate series. (authors)

Computer simulation of displacement cation exchange chromatography: separation of trivalent actinides and lanthanides

International Nuclear Information System (INIS)

Forsberg, C.W.

1980-05-01

A first-generation mathematical model of displacement cation exchange chromatography (CES) was constructed. The model incorporated the following phenomena: diffusion of cations up and down the column, diffusion of cations from the bulk liquid to the resin surface, and equilibrium of cations between liquid and solid resin beads. A limited number of experiments with rare earths using DTPA as the separation agent were undertaken to increase the current understanding of the processes involved in cation exchange chromatography. The numerical computer program based on the mathematical model was written in FORTRAN IV for use on the IBM 360 series of computers

Partnew - New solvent extraction processes for minor actinides - final report

International Nuclear Information System (INIS)

Madic, C.; Testard, F.; Hudson, M.J.; Liljenzin, J.O.; Christiansen, B.; Ferrando, M.; Facchini, A.; Geist, A.; Modolo, G.; Gonzalez-Espartero, A.; Mendoza, J. de

2004-01-01

The objectives of the European project PARTNEW were to define solvent extraction processes for the partitioning of the minor actinides, Am and Cm, from the aqueous high active raffinate or high active concentrate issuing the reprocessing of nuclear spent fuels by the PUREX process. Eleven laboratories participated to the research: 1/ CEA-DEN (Marcoule), 2/ CEA-DSM (Saclay), 3/ UREAD (U.K.), 4/ CTU (Sweden), 5/ ITU (Germany), 6/ ENEA (Italy), 7/ PoliMi (Italy), 8/ FZK-INE (Germany), 9/ FZJ-ISR (Germany), 10/ CIEMAT (Spain) and 11/ UAM (Spain). The research was organised into eight work packages (WP): Basic and applied DIAMEX studies, using diamide extractants for the co-extraction of actinides(III) (An(III)) and lanthanides(III) (Ln(III)) nitrates (WP1 and WP2), Basic and applied SANEX studies based on the use of polydentate N-ligands for the An(III)/Ln(III) separation (WP3 and WP4), Basic and applied SANEX studies based on the use of synergistic mixtures made of bis-(chloro-phenyl)-di-thio-phosphinic acid + neutral O-bearing ligand, (WP5 and WP6), Basic SANEX studies for the An(III)/Ln(III) separation, based on the use of new S-bearing ligands, Basic and applied studies for the Am(III)/Cm(III) separation. The work done in the fundamental and applied domains was very fruitful. Several processes have been successfully tested with genuine high active raffinates and concentrate. (authors)

Investigation of actinides speciation within the presence of ligands of interest for decorporation; Etude de la speciation des actinides vis-a-vis de ligands d'interet pour la decorporation

Energy Technology Data Exchange (ETDEWEB)

Bonin, L

2008-01-15

Data about the behaviour of actinides in biological media are required in order to investigate their decorporation. Those data are obtained through in vivo experiments and the study of chemical speciation of actinides within the presence of biological constituents. A part of this work consists in the development of a method leading to the determination of the speciation of actinides at the oxidation state +IV within the presence of a complexing species, as well as its structure. The method was applied to two types of ligands: 1) a constituent of blood plasma: the citrate anion. The various complexes formed were investigated and their formation constants were quantified. The coordination mode of the ligand was then clarified through a structural study of the complexes, underlining the role of only one carboxylic site and of the alcohol function. 2) chelating agents used for decorporation. The formation constants of complexes of An(IV) with NTA and DTPA were determined. The coordination number of the metallic cation in those complexes as well as the role of the nitrogen atom were proved. Lastly, the behaviour of Pu(IV) within the presence of LIHOPO was investigated. This chelating agent, more efficient than DTPA in the case of in vivo decorporation of Np, forms very stable complexes with the metallic cation. One of those complexes can be assumed to present a stoichiometry 2:3. (author)

Liquid-solid extraction of cationic metals by cationic amphiphiles

International Nuclear Information System (INIS)

Muller, W.

2010-01-01

In the field of selective separation for recycling of spent nuclear fuel, liquid-liquid extraction processes are widely used (PUREX, DIAMEX..) in industrial scale. In order to guarantee a sustainable nuclear energy for the forthcoming generations, alternative reprocessing techniques are under development. One of them bases on the studies from Heckmann et al in the 80's and consists in selectively precipitating actinides from aqueous waste solutions by cationic surfactants (liquid-solid extraction). This technique has some interesting advantages over liquid-liquid extraction techniques, because several steps are omitted like stripping or solvent washing. Moreover, the amount of waste is decreased considerably, since no contaminated organic solvent is produced. In this thesis, we have carried out a physico-chemical study to understand the specific interactions between the metallic cations with the cationic surfactant. First, we have analysed the specific effect of the different counter-ions (Cl - , NO 3 - , C 2 O 4 2- ) and then the effect of alkaline cations on the structural properties of the surfactant aggregation in varying thermodynamical conditions. Finally, different multivalent cations (Cu 2+ , Zn 2+ , UO 2 2+ , Fe 3+ , Nd 3+ , Eu 3+ , Th 4+ ) were considered; we have concluded that depending on the anionic complex of these metals formed in acidic media, we can observe either an adsorption at the micellar interface or not. This adsorption has a large influence of the surfactant aggregation properties and determines the limits of the application in term of ionic strength, temperature and surfactant concentration. (author) [fr

Structure and stability of hexa-aqua V(III) cations in vanadium redox flow battery electrolytes.

Science.gov (United States)

Vijayakumar, M; Li, Liyu; Nie, Zimin; Yang, Zhenguo; Hu, JianZhi

2012-08-07

The vanadium(III) cation structure in mixed acid based electrolyte solution from vanadium redox flow batteries is studied by (17)O and (35/37)Cl nuclear magnetic resonance (NMR) spectroscopy, electronic spectroscopy and density functional theory (DFT) based computational modelling. Both computational and experimental results reveal that the V(III) species can complex with counter anions (sulfate/chlorine) depending on the composition of its solvation sphere. By analyzing the powder precipitate it was found that the formation of sulfate complexed V(III) species is the crucial process in the precipitation reaction. The precipitation occurs through nucleation of neutral species formed through deprotonation and ion-pair formation process. However, the powder precipitate shows a multiphase nature which warrants multiple reaction pathways for precipitation reaction.

Rare earths and actinides

International Nuclear Information System (INIS)

Coqblin, B.

1982-01-01

This paper reviews the different properties of rare-earths and actinides, either as pure metals or as in alloys or compounds. Three different cases are considered: (i) First, in the case of 'normal' rare-earths which are characterized by a valence of 3, we discuss essentially the magnetic ordering, the coexistence between superconductivity and magnetism and the properties of amorphous rare-earth systems. (ii) Second, in the case of 'anomalous' rare-earths, we distinguish between either 'intermediate-valence' systems or 'Kondo' systems. Special emphasis is given to the problems of the 'Kondo lattice' (for compounds such as CeAl 2 ,CeAl 3 or CeB 6 ) or the 'Anderson lattice' (for compounds such as TmSe). The problem of neutron diffraction in these systems is also discussed. (iii) Third, in the case of actinides, we can separate between the d-f hybridized and almost magnetic metals at the beginning of the series and the rare-earth like the metals after americium. (orig.)

Actinide solubility in deep groundwaters - estimates for upper limits based on chemical equilibrium calculations

International Nuclear Information System (INIS)

Schweingruber, M.

1983-12-01

A chemical equilibrium model is used to estimate maximum upper concentration limits for some actinides (Th, U, Np, Pu, Am) in groundwaters. Eh/pH diagrams for solubility isopleths, dominant dissolved species and limiting solids are constructed for fixed parameter sets including temperature, thermodynamic database, ionic strength and total concentrations of most important inorganic ligands (carbonate, fluoride, phosphate, sulphate, chloride). In order to assess conservative conditions, a reference water is defined with high ligand content and ionic strength, but without competing cations. In addition, actinide oxides and hydroxides are the only solid phases considered. Recommendations for 'safe' upper actinide solubility limits for deep groundwaters are derived from such diagrams, based on the predicted Eh/pH domain. The model results are validated as far as the scarce experimental data permit. (Auth.)

Subtle interactions and electron transfer between U{sup III}, Np{sup III}, or Pu{sup III} and uranyl mediated by the oxo group

Energy Technology Data Exchange (ETDEWEB)

Arnold, Polly L.; Zegke, Markus; Hollis, Emmalina; Pecharman, Anne-Frederique; Love, Jason B. [EaStCHEM School of Chemistry, University of Edinburgh (United Kingdom); Dutkiewicz, Michal S. [EaStCHEM School of Chemistry, University of Edinburgh (United Kingdom); European Commission, Directorate for Nuclear Safety and Security, Joint Research Centre, Karlsruhe (Germany); Walter, Olaf; Apostolidis, Christos; Magnani, Nicola; Griveau, Jean-Christophe; Colineau, Eric; Caciuffo, Roberto [European Commission, Directorate for Nuclear Safety and Security, Joint Research Centre, Karlsruhe (Germany); Zhang, Xiaobin; Schreckenbach, Georg [Department of Chemistry, University of Manitoba, Winnipeg, MB (Canada)

2016-10-04

A dramatic difference in the ability of the reducing An{sup III} center in AnCp{sub 3} (An=U, Np, Pu; Cp=C{sub 5}H{sub 5}) to oxo-bind and reduce the uranyl(VI) dication in the complex [(UO{sub 2})(THF)(H{sub 2}L)] (L=''Pacman'' Schiff-base polypyrrolic macrocycle), is found and explained. These are the first selective functionalizations of the uranyl oxo by another actinide cation. At-first contradictory electronic structural data are explained by combining theory and experiment. Complete one-electron transfer from Cp{sub 3}U forms the U{sup IV}-uranyl(V) compound that behaves as a U{sup V}-localized single molecule magnet below 4 K. The extent of reduction by the Cp{sub 3}Np group upon oxo-coordination is much less, with a Np{sup III}-uranyl(VI) dative bond assigned. Solution NMR and NIR spectroscopy suggest Np{sup IV}U{sup V} but single-crystal X-ray diffraction and SQUID magnetometry suggest a Np{sup III}-U{sup VI} assignment. DFT-calculated Hirshfeld charge and spin density analyses suggest half an electron has transferred, and these explain the strongly shifted NMR spectra by spin density contributions at the hydrogen nuclei. The Pu{sup III}-U{sup VI} interaction is too weak to be observed in THF solvent, in agreement with calculated predictions. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Investigation of actinides speciation within the presence of ligands of interest for decorporation

International Nuclear Information System (INIS)

Bonin, L.

2008-01-01

Data about the behaviour of actinides in biological media are required in order to investigate their decorporation. Those data are obtained through in vivo experiments and the study of chemical speciation of actinides within the presence of biological constituents. A part of this work consists in the development of a method leading to the determination of the speciation of actinides at the oxidation state +IV within the presence of a complexing species, as well as its structure. The method was applied to two types of ligands: 1) a constituent of blood plasma: the citrate anion. The various complexes formed were investigated and their formation constants were quantified. The coordination mode of the ligand was then clarified through a structural study of the complexes, underlining the role of only one carboxylic site and of the alcohol function. 2) chelating agents used for decorporation. The formation constants of complexes of An(IV) with NTA and DTPA were determined. The coordination number of the metallic cation in those complexes as well as the role of the nitrogen atom were proved. Lastly, the behaviour of Pu(IV) within the presence of LIHOPO was investigated. This chelating agent, more efficient than DTPA in the case of in vivo decorporation of Np, forms very stable complexes with the metallic cation. One of those complexes can be assumed to present a stoichiometry 2:3. (author)

Actinide science. Fundamental and environmental aspects

International Nuclear Information System (INIS)

Choppin, Gregory R.

2005-01-01

Nuclear test explosions and reactor wastes have deposited an estimated 16x10 15 Bq of plutonium into the world's aquatic systems. However, plutonium concentration in open ocean waters is orders of magnitude less, indicating that most of the plutonium is quite insolvable in marine waters and has been incorporated into sediments. Actinide ions in waters often are not in a state of thermodynamic equilibrium and their solubility and migration behavior is related to the form in which the nuclides were introduced into the aquatic system. Actinide solubility depends on such factors as pH(hydrolysis), E H (oxidation state), reaction with complexants (e.g. carbonate, phosphate, humic acid, etc.) sorption to surfaces of minerals and/or colloids, etc., in the water. The most significant of these variables is the oxidation sate of the metal ion. The simultaneous presence of more than one oxidation state for some actinides (e.g. plutonium) in a solution complicates actinide environmental behavior. Both Np(V)O 2 + and Pu(V)O 2 + , the most significant soluble states in natural oxic waters are relatively noncomplexing and resistant to hydrolysis and subsequent precipitation but can undergo reduction to the Pu(IV) oxidation state with its different elemental behavior. The solubility of NpO 2 + can be as high as 10 -4 M while that of PuO 2 + is more limited by reduction to the insoluble tetravalent species, Pu(OH) 4 , (pK SP - 56). The net solubility of hexavalent UO 2 2+ in sea water is also limited by hydrolysis; however, it has a relatively high concentration due to formation of carbonate complexes. The insoluble trivalent americium hydroxocarbonate, Am(CO) 3 (OH), is the limiting species for the solubility of Am(III) in sea water. Thorium is found exclusively as the tetravalent species and its solubility is limited by the formation of quite insoluble Th(OH) 4 . The chemistry of actinide ions in the environment is reviewed to show the spectrum of reactions that can occur in

Interface reactions of actinides on muscovite; Grenzflaechenreaktionen von Actiniden an Muskovit

Energy Technology Data Exchange (ETDEWEB)

Hellebrandt, Stefan

2017-11-06

adsorbed U was detected at the muscovite interface according to all methods applied, despite the larger concentration of the adsorbate. This difference in the sorption behavior can be explained by the different redox behavior of U and Pu. U will stay mainly in its predominant oxidation state VI, due to its higher stability compared to Pu, while Pu will be present as Pu(VI), but also in a greater extent in its reduced oxidation states. Due to this difference Pu is able to form nanoparticles, whereas this is not the case for U. The third part compares the sorption of trivalent actinides Am(III) and Cm(III) and their homolog Eu(III) on alumino-silicates muscovite (phyllosilicate) and orthoclase (framework silicate). Under acidic conditions all elements adsorb as outer-sphere complexes, while the relative amount of inner-sphere sorption increases with increasing pH. At higher pH a transition from adsorbed aquoions to adsorbed hydrolysis-species and eventually a ternary sorption complex is observed. While TRLFS itself is a strong tool to investigate the speciation of metals in solution or in contact with a mineral surface the complementary use of SXS techniques is able to improve these findings. The results of this work, achieved by using modern methods such as X-ray scattering techniques (CTR/RAXR) and TRLFS, have afforded new insights into the surface reactivity of a wide range of actinides (Th, U, Pu, Am, and Cm) in contact with muscovite and orthoclase. New influence factors could be identified in the influence of the background electrolyte on the sorption behavior, where both cation and anion affect the actinide's retention. The different redox behavior of redox-active actinides like U and Pu also influenced the sorption behavior tremendously, even in contact with the redox-inactive mineral muscovite. The complementary use of surface X-ray diffraction and laser spectroscopic methods was instrumental to enable us to investigate the distribution, occupancy, and

Local structure near actinides and nucleating elements in borosilicate glass for nuclear industry: Results of X-ray absorption spectroscopy

International Nuclear Information System (INIS)

Petit-Maire, D.

1988-01-01

Possibilities and limits of X-ray absorption spectroscopy for cation site description in silicate glasses and possible applications for complex glasses, like glass for fission product containment, are examined. In borosilicate glasses two types of sites are evidenced for actinides at the valence 4: Coordinance 6 sites with a narrow radial distribution for the distance An-0; higher coordination (7, 8 or more) with a wider and asymmetrical radial distribution. Proportion of low coordinance sites increases when cation size decreases (Th > Np). U and Np VI and V are characterized as actinyles with a chain 0-An-0 practically linear, coordinance in a plane perpendicular to this complex is probably 5. X-ray absorption spectroscopy allows an accurate description of actinide sites in fission product glasses [fr

The complex formation of selected actinides (U, Np, Cm) with microbial ligands

International Nuclear Information System (INIS)

Glorius, Maja

2009-01-01

One of the urgent tasks in the field of nuclear technology is the final storage of radioactive substances. As a part of the safety requirements the protection of humans and the environment from the danger of radioactive substances in case of the release from the final storage is essential. For performing long-term safety calculations the detailed understanding of the physico-chemical effects and influences which cause the mobilisation and transport of actinides are necessary. The presented work was a discrete part of a project, which was focused on the clarification of the influence of microorganisms on the migration of actinides in case of the release of actinides from a final storage. The influence of microbial produced substances on the mobilisation of selected actinides was studied thereby. The microbial produced substances studied in this project were synthesized by bacteria from the Pseudomonas genus under special conditions. Fluorescent Pseudomonads secrete bacterial pyoverdin-type siderophores with a high potential to complex and transport metals, especially iron(III). The aim of the project was to determine how and under which conditions the bioligands are able to complex also radioactive substances and therefore to transport them. For this work the alpha-emitting actinides uranium, curium and neptunium were chosen because their long-life cycle and their radiotoxicity are a matter of particular interest. This work dealed with the interaction of the actinides U(VI), Np(V) and Cm(III) with model ligands simulating the functionality of the pyoverdins. So, such bioligands can essentially influence the behaviour of actinides in the environment. The results of this work contribute to a better understanding and assessment of the influence of the microbial ligands to the mobilisation and migration of the radionuclides. The outcomes could be used to quantify the actinide-mobilising effect of the bioligands, which are released, for example, in the vicinity of a

Synthesis and characterisation of nitrogen-containing poly heterocyclic molecules for the complexation of polluting metal cations

International Nuclear Information System (INIS)

Leconte, N.

2007-12-01

The recovery of actinides(III) from the mixture actinides(III)/lanthanides(III) is a great deal of the nuclear waste management. Experiences have shown that derivatives of 2,6- bis(1,2,4-triazine-3-yl)pyridine (BTP) are able to extract selectively actinides(III) from lanthanides(III). But the properties of these molecules need to be reinforced to exhibit best extraction performances and to resist to the harsh conditions of the extracting processes. Originally functionalized ligands were synthesized and tested in a radioactive medium. In a second part, this work focuses on the control and the detection of actinides(III). This could be done thanks to the use of a chemical sensor such as quartz crystal microbalance. The study of this apparatus required the preliminary synthesis of original complexing BTP-derived structures. The last part of this work deals with the study of new synthetic ways to afford the BTP moiety. The palladium-catalyzed cross-coupling reaction of 3-methylthio-1,2,4-triazine with various 2-stannylated pyridines have been explored. Our investigations have also allowed to develop a method for synthesizing unsymmetrical 1,2,4,5-tetrazine from the cross-coupling reaction between 3-methylthio-6-(morpholine-N-yl)-1,2,4,5-tetrazine and organoboron / organo-stannane derivatives. (author)

A literature review of actinide-carbonate mineral interactions

International Nuclear Information System (INIS)

Stout, D.L.

1993-10-01

Chemical retardation of actinides in groundwater systems is a potentially important mechanism for assessing the performance of the Waste Isolation Pilot Plant (WIPP), a facility intended to demonstrate safe disposal of transuranic waste. Rigorous estimation of chemical retardation during transport through the Culebra Dolomite, a water-bearing unit overlying the WIPP, requires a mechanistic understanding of chemical reactions between dissolved elements and mineral surfaces. This report represents a first step toward this goal by examining the literature for pertinent experimental studies of actinide-carbonate interactions. A summary of existing models is given, along with the types of experiments on which these models are based. Articles pertaining to research into actinide interactions with carbonate minerals are summarized. Select articles involving trace element-carbonate mineral interactions are also reviewed and may serve as templates for future research. A bibliography of related articles is included. Americium(III), and its nonradioactive analog neodymium(III), partition strongly from aqueous solutions into carbonate minerals. Recent thermodynamic, kinetic, and surface studies show that Nd is preferentially removed from solution, forming a Nd-Ca carbonate solid solution. Neptunium(V) is rapidly removed from solution by carbonates. Plutonium incorporation into carbonates is complicated by multiple oxidation states. Little research has been done on the radium(H) and thorium(IV) carbonate systems. Removal of uranyl ion from solution by calcite is limited to monolayer surface coverage

A novel dipicolinamide-dicarbollide synergistic solvent system for actinide extraction

Energy Technology Data Exchange (ETDEWEB)

Patil, Ajay Bhagwan [Bhabha Atomic Research Centre, Mumbai (India). Radiochemistry Div.; Pune Univ. (India). Garware Research Centre; Pathak, Priyanath; Mohapatra, Prasanta Kumar [Bhabha Atomic Research Centre, Mumbai (India). Radiochemistry Div.; Shinde, Vaishali Sanjay [Pune Univ. (India). Garware Research Centre; Alyapyshev, M.Yu.; Babain, Vasiliy A. [Federal Agency for Atomic Energy, St. Petersburg (Russian Federation). V.G. Khlopin Radium Institute

2014-09-01

Solvent extraction studies of several actinide ions such as Am(III), U(VI), Np(IV), Np(VI), Pu(IV) were carried out from nitric acid medium using a synergistic mixture of N,N'-diethyl-N,N'-di(para)fluorophenyl-2,6-dipicolinamide, (DEtD(p)FPhDPA, DPA), and hydrogen dicarbollylcobaltate (H{sup +}CCD{sup -}) dissolved in phenyltrifluoromethylsulphone (PTMS). The effects of different parameters such as aqueous phase acidity (0.01-3 M HNO{sub 3}), oxidation states of metal ions, ligand concentration, nature of diluent and temperature on the extraction behavior of metal ions were studied. The extracted Am(III) species was determined as H{sup +}[Am(DPA){sub 2}(CCD){sub 4}]{sup -} With increasing aqueous phase acidities, the extractability of both Am(III) and Eu(III) was found to decrease. The synergistic mixture showed better extraction in mM concentrations as compared to previously studied dipicolinamides. The thermodynamic studies were performed to calculate heat of extraction reaction and the extraction constants. The proposed synergistic mixture showed good extraction for all the metal ions, though lanthanide actinide separation results are not encouraging. (orig.)

Actinide chemistry research supporting the Waste Isolation Pilot Plant (WIPP): FY94 results

Energy Technology Data Exchange (ETDEWEB)

Novak, C.F. [ed.

1995-08-01

This document contains six reports on actinide chemistry research supporting the Waste Isolation Pilot Plant (WIPP). These reports, completed in FY94, are relevant to the estimation of the potential dissolved actinide concentrations in WIPP brines under repository breach scenarios. Estimates of potential dissolved actinide concentrations are necessary for WIPP performance assessment calculations. The specific topics covered within this document are: the complexation of oxalate with Th(IV) and U(VI); the stability of Pu(VI) in one WIPP-specific brine environment both with and without carbonate present; the solubility of Nd(III) in a WIPP Salado brine surrogate as a function of hydrogen ion concentration; the steady-state dissolved plutonium concentrations in a synthetic WIPP Culebra brine surrogate; the development of a model for Nd(III) solubility and speciation in dilute to concentrated sodium carbonate and sodium bicarbonate solutions; and the development of a model for Np(V) solubility and speciation in dilute to concentrated sodium Perchlorate, sodium carbonate, and sodium chloride media.

Actinide chemistry research supporting the Waste Isolation Pilot Plant (WIPP): FY94 results

International Nuclear Information System (INIS)

Novak, C.F.

1995-08-01

This document contains six reports on actinide chemistry research supporting the Waste Isolation Pilot Plant (WIPP). These reports, completed in FY94, are relevant to the estimation of the potential dissolved actinide concentrations in WIPP brines under repository breach scenarios. Estimates of potential dissolved actinide concentrations are necessary for WIPP performance assessment calculations. The specific topics covered within this document are: the complexation of oxalate with Th(IV) and U(VI); the stability of Pu(VI) in one WIPP-specific brine environment both with and without carbonate present; the solubility of Nd(III) in a WIPP Salado brine surrogate as a function of hydrogen ion concentration; the steady-state dissolved plutonium concentrations in a synthetic WIPP Culebra brine surrogate; the development of a model for Nd(III) solubility and speciation in dilute to concentrated sodium carbonate and sodium bicarbonate solutions; and the development of a model for Np(V) solubility and speciation in dilute to concentrated sodium Perchlorate, sodium carbonate, and sodium chloride media

Minor Actinide Separations Using Ion Exchangers Or Ionic Liquids

International Nuclear Information System (INIS)

Hobbs, D.; Visser, A.; Bridges, N.

2011-01-01

This project seeks to determine if (1) inorganic-based ion exchange materials or (2) electrochemical methods in ionic liquids can be exploited to provide effective Am and Cm separations. Specifically, we seek to understand the fundamental structural and chemical factors responsible for the selectivity of inorganic-based ion-exchange materials for actinide and lanthanide ions. Furthermore, we seek to determine whether ionic liquids can serve as the electrolyte that would enable formation of higher oxidation states of Am and other actinides. Experiments indicated that pH, presence of complexants and Am oxidation state exhibit significant influence on the uptake of actinides and lanthanides by layered sodium titanate and hybrid zirconium and tin phosphonate ion exchangers. The affinity of the ion exchangers increased with increasing pH. Greater selectivity among Ln(III) ions with sodium titanate materials occurs at a pH close to the isoelectric potential of the ion exchanger. The addition of DTPA decreased uptake of Am and Ln, whereas the addition of TPEN generally increases uptake of Am and Ln ions by sodium titanate. Testing confirmed two different methods for producing Am(IV) by oxidation of Am(III) in ionic liquids (ILs). Experimental results suggest that the unique coordination environment of ionic liquids inhibits the direct electrochemical oxidation of Am(III). The non-coordinating environment increases the oxidation potential to a higher value, while making it difficult to remove the inner coordination of water. Both confirmed cases of Am(IV) were from the in-situ formation of strong chemical oxidizers.

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

Directory of Open Access Journals (Sweden)

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.

Actinide metal processing

International Nuclear Information System (INIS)

Sauer, N.N.; Watkin, J.G.

1992-01-01

A process for converting an actinide metal such as thorium, uranium, or plutonium to an actinide oxide material by admixing the actinide metal in an aqueous medium with a hypochlorite as an oxidizing agent for sufficient time to form the actinide oxide material and recovering the actinide oxide material is described together with a low temperature process for preparing an actinide oxide nitrate such as uranyl nitrate. Additionally, a composition of matter comprising the reaction product of uranium metal and sodium hypochlorite is provided, the reaction product being an essentially insoluble uranium oxide material suitable for disposal or long term storage

Synthesis of tetravalent actinide chlorides. Versatile compounds for actinide chemistry

Energy Technology Data Exchange (ETDEWEB)

Maerz, Juliane [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Div. Chemistry of the F-Elements

2016-07-01

Anhydrous actinide tetrachlorides (AnCl{sub 4}) were synthesized under mild conditions to provide versatile compounds for actinide chemistry. They enable a direct access to actinide complexes with organic and inorganic ligands.

Subtle interactions and electron transfer between UIII, NpIII, or PuIII and uranyl mediated by the oxo group

International Nuclear Information System (INIS)

Arnold, Polly L.; Zegke, Markus; Hollis, Emmalina; Pecharman, Anne-Frederique; Love, Jason B.; Dutkiewicz, Michal S.; Walter, Olaf; Apostolidis, Christos; Magnani, Nicola; Griveau, Jean-Christophe; Colineau, Eric; Caciuffo, Roberto; Zhang, Xiaobin; Schreckenbach, Georg

2016-01-01

A dramatic difference in the ability of the reducing An III center in AnCp 3 (An=U, Np, Pu; Cp=C 5 H 5 ) to oxo-bind and reduce the uranyl(VI) dication in the complex [(UO 2 )(THF)(H 2 L)] (L=''Pacman'' Schiff-base polypyrrolic macrocycle), is found and explained. These are the first selective functionalizations of the uranyl oxo by another actinide cation. At-first contradictory electronic structural data are explained by combining theory and experiment. Complete one-electron transfer from Cp 3 U forms the U IV -uranyl(V) compound that behaves as a U V -localized single molecule magnet below 4 K. The extent of reduction by the Cp 3 Np group upon oxo-coordination is much less, with a Np III -uranyl(VI) dative bond assigned. Solution NMR and NIR spectroscopy suggest Np IV U V but single-crystal X-ray diffraction and SQUID magnetometry suggest a Np III -U VI assignment. DFT-calculated Hirshfeld charge and spin density analyses suggest half an electron has transferred, and these explain the strongly shifted NMR spectra by spin density contributions at the hydrogen nuclei. The Pu III -U VI interaction is too weak to be observed in THF solvent, in agreement with calculated predictions. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

TAILORING INORGANIC SORBENTS FOR SRS STRONTIUM AND ACTINIDE SEPARATIONS: MODIFIED MONOSODIUM TITANATE PHASE III FINAL REPORT

Energy Technology Data Exchange (ETDEWEB)

Taylor-Pashow, K.; Hobbs, D.

2010-09-01

This document provides a final report of Phase III testing activities for the development of modified monosodium titanate (mMST), which exhibits improved strontium and actinide removal characteristics compared to the baseline MST material. The activities included characterization of the crystalline phases present at varying temperatures, solids settling characteristics, quantification of the peroxide content; evaluation of the post-synthesis gas release under different conditions; the extent of desorption of {sup 85}Sr, Np, and Pu under washing conditions; and the effects of age and radiation on the performance of the mMST. Key findings and conclusions include the following. The peroxide content of several mMST samples was determined using iodometric titration. The peroxide content was found to decrease with age or upon extended exposure to elevated temperature. A loss of peroxide was also measured after exposure of the material to an alkaline salt solution similar in composition to the simulated waste solution. To determine if the loss of peroxide with age affects the performance of the material, Sr and actinide removal tests were conducted with samples of varying age. The oldest sample (4 years and 8 months) did show lower Sr and Pu removal performance. When compared to the youngest sample tested (1 month), the oldest sample retained only 15% of the DF for Pu. Previous testing with this sample indicated no decrease in Pu removal performance up to an age of 30 months. No loss in Np removal performance was observed for any of the aged samples, and no uptake of uranium occurred at the typical sorbent loading of 0.2 g/L. Additional testing with a uranium only simulant and higher mMST loading (3.0 g/L) indicated a 10% increase of uranium uptake for a sample aged 3 years and 8 months when compared to the results of the same sample measured at an age of 1 year and 5 months. Performance testing with both baseline-MST and mMST that had been irradiated in a gamma source to

Thermodynamics and Structure of Actinide(IV) Complexes with Nitrilotriacetic Acid

Energy Technology Data Exchange (ETDEWEB)

Bonin, L.; Guillaumont, D.; Jeanson, A.; Den Auwer, C.; Moisy, Ph. [CEA Marcoule, DEN, DRCP, SCPS, F-30207 Bagnols Sur Ceze (France); Grigoriev, M. [RAS, AN Frumkin Inst Phys Chem and Electrochem, Moscow 119991 (Russian Federation); Berthet, J.C. [CEA Saclay, DSM, IRAMIS, URA 331, Serv Chim Mol, CNRS, F-91191 Gif Sur Yvette (France); Hennig, C.; Scheinost, A. [Forschungszentrum Dresden Rossendorf, Inst Radiochem, D-01314 Dresden (Germany)

2009-05-15

Nitrilotriacetic acid, commonly known as NITA (N(CH{sub 2}CO{sub 2}H){sub 3}), can be considered a representative of the polyamino-carboxylic family. The results presented in this paper describe the thermodynamical complexation and structural investigation of An(IV) complexes with NTA in aqueous solution. In the first part, the stability constants of the An(IV) complexes (An = Pu, Np, U, and Th) have been determined by spectrophotometry. In the second part, the coordination spheres of the actinide cation in these complexes have been described using extended X-ray absorption fine structure spectroscopy and compared to the solid-state structure of (Hpy){sub 2}[U(NTA){sub 2}].H{sub 2}O. These data are further compared to quantum chemical calculations, and their evolution across the actinide series is discussed. In particular, an interpretation of the role of the nitrogen atom in the coordination mode is proposed. These results are considered to be model behavior of polyamino-carboxylic ligands such as diethylenetriamine pentaacetic acid, which is nowadays the best candidate for a chelating agent in the framework of actinide decorporation for the human body. (authors)

Development and demonstration of innovative partitioning processes (i-SANEX and 1-cycle SANEX) for actinide partitioning

International Nuclear Information System (INIS)

Wilden, Andreas; Modolo, Giuseppe; Geist, Andreas

2015-01-01

For the recovery of the trivalent actinides Am(III) and Cm(III) from PUREX raffinate, two innovative partitioning processes were developed within the European project ACSEPT. In the 'innovative-SANEX' concept, trivalent actinides (An(III)) and lanthanides (Ln(III)) are co-extracted by a TODGA-based solvent, which is then subjected to several stripping steps: selective stripping of An(III) with the hydrophilic ligand SO 3 -Ph-BTP, followed by subsequent stripping of Ln(III). A more challenging route studied also within our laboratories is the direct An(III) separation using a mixture of CyMe 4 BTBP and TODGA, the so-called '1-cycle SANEX' process. Both processes have been successfully demonstrated using spiked simulate solutions in laboratory-scale miniature annular centrifugal contactors using 32-stages flowsheets. The process development and results of the demonstration tests will be presented and discussed. Both processes showed a high recovery of An(III) with high fission-product decontamination factors. The safety of these processes is studied within the current European project SACSESS. (authors)

Effects of humic substances on the migration of radionuclides: Complexation of actinides with humic substances. 3. Progress report

International Nuclear Information System (INIS)

Kim, J.I.; Rhee, D.S.; Buckau, G.; Moulin, V.; Tits, J.; Decambox, P.; Franz, C.; Herrmann, G.; Trautmann, N.; Dierckx, A.; Vancluysen, J.; Maes, A.

1993-03-01

The aim of the present research programme is to study the complexation behaviour of actinide ions with humic substances in natural aquifer systems and hence to quantify the effect of humic substances on the actinide migration. Aquatic humic substances commonly found in all groundwaters in different concentrations have a strong tendency towards complexation with actinide ions. This is one of the major geochemical reactions but hitherto least quantified. Therefore, the effect of humic substances on the actinide migration is poorly understood. In the present research programme the complexation of actinide ions with humic substances will be described thermodynamically. This description will be based on a model being as simple as possible to allow an easy introduction of the resulting reaction constants into geochemical modelling of the actinide migration. This programme is a continuation of the activities of the COCO group in the second phase of the CEC-MIRAGE project. The programme consists of the following three main tasks: Task 1: Complexation reactions of actinide ions with well characterized reference and site-specific humic and fulvic acids; Task 2: Competition reactions with major cations in natural groundwaters; Task 3: Validation of the complexation data in natural aquatic systems by comparison of calculation with spectroscopic experiment. (orig./EF)

Simulations of the Thermodynamic and Diffusion Properties of Actinide Oxide Fuel Materials

International Nuclear Information System (INIS)

Becker, Udo

2013-01-01

Spent nuclear fuel from commercial reactors is comprised of 95-99 percent UO 2 and 1-5 percent fission products and transuranic elements. Certain actinides and fission products are of particular interest in terms of fuel stability, which affects reprocessing and waste materials. The transuranics found in spent nuclear fuels are Np, Pu, Am, and Cm, some of which have long half- lives (e.g., 2.1 million years for 237 Np). These actinides can be separated and recycled into new fuel matrices, thereby reducing the nuclear waste inventory. Oxides of these actinides are isostructural with UO 2 , and are expected to form solid solutions. This project will use computational techniques to conduct a comprehensive study on thermodynamic properties of actinide-oxide solid solutions. The goals of this project are to: Determine the temperature-dependent mixing properties of actinide-oxide fuels; Validate computational methods by comparing results with experimental results; Expand research scope to complex (ternary and quaternary) mixed actinide oxide fuels. After deriving phase diagrams and the stability of solid solutions as a function of temperature and pressure, the project team will determine whether potential phase separations or ordered phases can actually occur by studying diffusion of cations and the kinetics of potential phase separations or ordered phases. In addition, the team will investigate the diffusion of fission product gases that can also have a significant influence on fuel stability. Once the system has been established for binary solid solutions of Th, U, Np, and Pu oxides, the methodology can be quickly applied to new compositions that apply to ternaries and quaternaries, higher actinides (Am, Cm), burnable poisons (B, Gd, Hf), and fission products (Cs, Sr, Tc) to improve reactivity

Complexes of actinides with naturally occuring organic substances - Literature survey

International Nuclear Information System (INIS)

Olofsson, U.; Allard, B.

1983-02-01

Properties of naturally occurring humic and fulvic acids and their formation of actinide complexes are reviewed. Actinides in all the oxdation states III, IV, V and VI would form complexes with many humic and fulvic acids, comparable in strength to the hydroxide and carbonate complexes. Preliminary experiments have shown, that the presence of predominantly humic acid complexes would significantly reduce the sorption of americium on geologic media. This does not, however, necessarily lead to a potentially enhanced mobility under environmental conditions, since humic and fulvic acids carrying trace metals also would be strongly bound to e.g. clayish material. (author)

Actinide separation by electrorefining

International Nuclear Information System (INIS)

Fusselman, S.P.; Gay, R.L.; Grantham, L.F.; Grimmett, D.L.; Roy, J.J.; Inoue, T.; Hijikata, T.; Krueger, C.L.; Storvick, T.S.; Takahashi, N.

1995-01-01

TRUMP-S is a pyrochemical process being developed for the recovery of actinides from PUREX wastes. This paper describes development of the electrochemical partitioning step for recovery of actinides in the TRUMP-S process. The objectives are to remove 99 % of each actinide from PUREX wastes, with a product that is > 90 % actinides. Laboratory tests indicate that > 99 % of actinides can be removed in the electrochemical partitioning step. A dynamic (not equilibrium) process model predicts that 90 wt % product actinide content can be achieved through 99 % actinide removal. Accuracy of model simulation results were confirmed in tests with rare earths. (authors)

Swedish-German actinide migration experiment at ÄSPÖ hard rock laboratory

Science.gov (United States)

Kienzler, B.; Vejmelka, P.; Römer, J.; Fanghänel, E.; Jansson, M.; Eriksen, T. E.; Wikberg, P.

2003-03-01

Within the scope of a bilateral cooperation between Svensk Kärnbränslehantering (SKB) and Forschungszentrum Karlsruhe, Institut für Nukleare Entsorgung (FZK-INE), an actinide migration experiment is currently being performed at the Äspö Hard Rock Laboratory (HRL) in Sweden. This paper covers laboratory and in situ investigations on actinide migration in single-fractured granite core samples. For the in situ experiment, the CHEMLAB 2 probe developed by SKB was used. The experimental setup as well as the breakthrough of inert tracers and of the actinides Am, Np and Pu are presented. The breakthrough curves of inert tracers were analyzed to determine hydraulic properties of the fractured samples. Postmortem analyses of the solid samples were performed to characterize the flow path and the sorbed actinides. After cutting the cores, the abraded material was analyzed with respect to sorbed actinides. The slices were scanned optically to visualize the flow path. Effective volumes and inner surface areas were measured. In the experiments, only breakthrough of Np(V) was observed. In each experiment, the recovery of Np(V) was ≤40%. Breakthrough of Am(III) and Pu(IV) as well as of Np(IV) was not observed.

The interaction of actinide and lanthanide ions with hemoglobin and its relevance to human and environmental toxicology

Energy Technology Data Exchange (ETDEWEB)

Kumar, Amit, E-mail: amitk@barc.gov.in [Radiation Biology and Health Sciences Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Ali, Manjoor [Radiation Biology and Health Sciences Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Ningthoujam, Raghumani S. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Gaikwad, Pallavi [Department of Zoology, Savitribai Phule Pune University, Pune 411 007, Mumbai (India); Kumar, Mukesh [Solid State, Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Nath, Bimalendu B. [Department of Zoology, Savitribai Phule Pune University, Pune 411 007, Mumbai (India); Pandey, Badri N. [Radiation Biology and Health Sciences Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)

2016-04-15

Highlights: • The sites of Ln and An interaction in Hb depend upon their charge-to-ionic-radii ratio. • Th(IV), Ce(IV) and U(VI) altered structure and oxygen-binding of Hb. • Spectroscopic studies determined binding characteristics of actinides. • Metal–Hb interaction was tested in an environmentally-important aquatic midge, Chironomus. - Abstract: Due to increasing use of lanthanides/actinides in nuclear and civil applications, understanding the impact of these metal ions on human health and environment is a growing concern. Hemoglobin (Hb), which occurs in all the kingdom of living organism, is the most abundant protein in human blood. In present study, effect of lanthanides and actinides [thorium: Th(IV), uranium: U(VI), lanthanum: La(III), cerium: Ce(III) and (IV)] on the structure and function of Hb has been investigated. Results showed that these metal ions, except Ce(IV) interacted with carbonyl and amide groups of Hb, which resulted in the loss of its alpha-helix conformation. However, beyond 75 μM, these ions affected heme moiety. Metal–heme interaction was found to affect oxygen-binding of Hb, which seems to be governed by their closeness with the charge-to-ionic-radius ratio of iron(III). Consistently, Ce(IV) being closest to iron(III), exhibited a greater effect on heme. Binding constant and binding stoichiometry of Th(IV) were higher than that of U(VI). Experiments using aquatic midge Chironomus (possessing human homologous Hb) and human blood, further validated metal–Hb interaction and associated toxicity. Thus, present study provides a biochemical basis to understand the actinide/lanthanide-induced interference in heme, which may have significant implications for the medical and environmental management of lanthanides/actinides toxicity.

The interaction of actinide and lanthanide ions with hemoglobin and its relevance to human and environmental toxicology

International Nuclear Information System (INIS)

Kumar, Amit; Ali, Manjoor; Ningthoujam, Raghumani S.; Gaikwad, Pallavi; Kumar, Mukesh; Nath, Bimalendu B.; Pandey, Badri N.

2016-01-01

Highlights: • The sites of Ln and An interaction in Hb depend upon their charge-to-ionic-radii ratio. • Th(IV), Ce(IV) and U(VI) altered structure and oxygen-binding of Hb. • Spectroscopic studies determined binding characteristics of actinides. • Metal–Hb interaction was tested in an environmentally-important aquatic midge, Chironomus. - Abstract: Due to increasing use of lanthanides/actinides in nuclear and civil applications, understanding the impact of these metal ions on human health and environment is a growing concern. Hemoglobin (Hb), which occurs in all the kingdom of living organism, is the most abundant protein in human blood. In present study, effect of lanthanides and actinides [thorium: Th(IV), uranium: U(VI), lanthanum: La(III), cerium: Ce(III) and (IV)] on the structure and function of Hb has been investigated. Results showed that these metal ions, except Ce(IV) interacted with carbonyl and amide groups of Hb, which resulted in the loss of its alpha-helix conformation. However, beyond 75 μM, these ions affected heme moiety. Metal–heme interaction was found to affect oxygen-binding of Hb, which seems to be governed by their closeness with the charge-to-ionic-radius ratio of iron(III). Consistently, Ce(IV) being closest to iron(III), exhibited a greater effect on heme. Binding constant and binding stoichiometry of Th(IV) were higher than that of U(VI). Experiments using aquatic midge Chironomus (possessing human homologous Hb) and human blood, further validated metal–Hb interaction and associated toxicity. Thus, present study provides a biochemical basis to understand the actinide/lanthanide-induced interference in heme, which may have significant implications for the medical and environmental management of lanthanides/actinides toxicity.

EUROPART: an European integrated project on actinide partitioning

International Nuclear Information System (INIS)

Madic, C.; Baron, P.; Hudson, M.J.

2006-01-01

Full text of publication follows: The EUROPART project is a scientific integrated project between 24 European partners, from 10 countries, mostly funded by the European Community within the FP6, together with CRIEPI from Japan and ANSTO from Australia. EUROPART aims at developing chemical partitioning processes for the so-called minor actinides (MA) contained in nuclear wastes, i.e. from Am to Cf. In the case of the treatment of dedicated spent fuels or targets, the actinides to be separated also include U, Pu and Np. The techniques considered for the separation of these radionuclides belong to the fields of hydrometallurgy and pyrometallurgy, as in the previous European FP5 programs named PARTNEW, CALIXPART and PYROREP, respectively. The two main axes of research within EUROPART are: 1/ the partitioning of MA (from Am to Cf) from wastes issuing from the reprocessing of high burn-up UOX fuels and multi-recycled MOX fuels, 2/ the partitioning of the whole actinide family of elements for recycling, as an option for advanced dedicated fuel cycles (this work will be connected to the studies to be performed within the EUROTRANS European integrated project). In hydrometallurgy, the research is organized in five Work Packages (WP). Four are dedicated to the study of partitioning methods mainly based on the use of solvent extraction methods and of solid extractants, one WP is dedicated to the development of actinide co-conversion methods for fuel or target preparations. The research in pyrometallurgy is organized into four WPs, listed hereafter: (i) study of the basic chemistry of transuranium elements and of some fission products in molten salts (chlorides, fluorides), (ii) development of actinide partitioning methods, (iii) study of the conditioning of the salt wastes, (iv) system studies. Moreover, a strong management team is concerned not only with the technical and financial issues arising from EUROPART, but also with information, communication and benefits for Europe

Sigma Team for Advanced Actinide Recycle FY2015 Accomplishments and Directions

Energy Technology Data Exchange (ETDEWEB)

Moyer, Bruce A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2015-09-30

The Sigma Team for Minor Actinide Recycle (STAAR) has made notable progress in FY 2015 toward the overarching goal to develop more efficient separation methods for actinides in support of the United States Department of Energy (USDOE) objective of sustainable fuel cycles. Research in STAAR has been emphasizing the separation of americium and other minor actinides (MAs) to enable closed nuclear fuel recycle options, mainly within the paradigm of aqueous reprocessing of used oxide nuclear fuel dissolved in nitric acid. Its major scientific challenge concerns achieving selectivity for trivalent actinides vs lanthanides. Not only is this challenge yielding to research advances, but technology concepts such as ALSEP (Actinide Lanthanide Separation) are maturing toward demonstration readiness. Efforts are organized in five task areas: 1) combining bifunctional neutral extractants with an acidic extractant to form a single process solvent, developing a process flowsheet, and demonstrating it at bench scale; 2) oxidation of Am(III) to Am(VI) and subsequent separation with other multivalent actinides; 3) developing an effective soft-donor solvent system for An(III) selective extraction using mixed N,O-donor or all-N donor extractants such as triazinyl pyridine compounds; 4) testing of inorganic and hybrid-type ion exchange materials for MA separations; and 5) computer-aided molecular design to identify altogether new extractants and complexants and theory-based experimental data interpretation. Within these tasks, two strategies are employed, one involving oxidation of americium to its pentavalent or hexavalent state and one that seeks to selectively complex trivalent americium either in the aqueous phase or the solvent phase. Solvent extraction represents the primary separation method employed, though ion exchange and crystallization play an important role. Highlights of accomplishments include: Confirmation of the first-ever electrolytic oxidation of Am(III) in a

Synthesis of a 3D lanthanum(III) MOFs as a multi-chemosensor to Cr(VI)-containing anion and Fe(III) cation based on a flexible ligand

Science.gov (United States)

Ma, Yang-Min; Liu, Tong; Huang, Wen-Huan

2018-02-01

Based on La(NO3)3·6H2O and 4,4‧-((5-carboxy-1,3-phenylene)bis(oxy))dibenzoic acid (H3cpbda), a 3D porous MOFs, [La(cpbda)(H2O)1.5]n (1), was synthesized by hydrothermal method and further characterized by single-crystal X-ray diffraction, power X-ray diffraction, IR spectroscopy, thermal-gravimetric analysis and fluorescence spectroscopy. Owing to its good stabilities and fluorescence property, the sensing experiments on sixteen cations and eleven anions were implemented. Moreover, the further titration processes show 1 can sensitively detect the Fe(III) cation and Cr(VI)-containing anions by quenching responses.

Selective extraction of trivalent actinides with hard-soft mixed donor ligands: role of intra-ligand synergism

International Nuclear Information System (INIS)

Ghanty, Tapan K.

2016-01-01

In recent years, considerable attention has been given to understand the coordination chemistry of trivalent lanthanide (Ln) and actinide (An) with various ligands because of its close link with the nuclear waste management processes. It is well known that lanthanide-actinide separation is a challenging and difficult task because of very similar chemical properties of these two series of ions, which are associated with similar ionic radii and coordination numbers. Recently, we have introduced a new concept, 'intra-ligand synergism', where hard donor atom, such as, oxygen preferentially binds to trivalent actinides (An(III)) as compared to the valence iso-electronic trivalent lanthanides (Ln(III)) in presence of another soft donor centre. In the present work, the conventional concept of selective complexation of actinides with soft donor ligands (either S or N donor) has been modified through exploiting this concept, and thereby the higher selectivity of 1,10-phenanthroline-2,9-dicarboxylamide (PDAM) based ligands, namely PDAM and its isobutyl and decyl derivatives towards Am(III) ion has been predicted theoretically through density functional calculations. Subsequently, several such amide derivatives have been synthesized to optimize the solubility of the ligands in organic phase. Finally, solvent extraction experiments have been carried out to validate the theoretical prediction on the selectivity of oxygen donor ligands towards Am(III) as compared to Eu(III), and a maximum separation factor of about 51 has been achieved experimentally using 2,9-bis(N-decylaminocarbonyl)-1,10-phenanthroline ligand. The separation factor is increased with the decrease in pH, which is very interesting since extraction of the Am 3+ ion is considered to be important under highly acidic conditions from the nuclear waste management point of view. (author)

Modelling thermodynamic properties of lanthanide (LnL)3+ and actinide (AnL)3+ complexes with tridentate planar nitrogen ligands (L)

International Nuclear Information System (INIS)

Ionova, G.; Rabbe, C.; Charbonnel, M.C.; Hill, C.; Guillaumont, D.; Guillaumont, R.; Ionov, S.; Madic, C.

2004-01-01

We report here the results obtained from a systematic theoretical study on the thermodynamic properties of trivalent lanthanide (Ln) and actinide (An) complexes with chelating nitrogen tridentate ligands. The mechanism of chelation has been investigated and the role of cation dissolution is investigated through a comparison of the thermodynamic properties of solvated cations and complexes. The difference in thermodynamic properties of LnL and AnL complexes is analyzed. (authors)

Ordered perovskites with cationic vacancies. 9. Compounds of the type Sr/sub 2/Srsub(1/4)Bsub(1/2)sup(III)vacantsub(1/4)WO/sub 6/ equivalent to Sr/sub 8/SrB/sub 2/sup(III)vacantW/sub 4/O/sub 24/ (Bsup(III) = La, Pr, Nd, Sm - Tm, Y)

Energy Technology Data Exchange (ETDEWEB)

Kemmler-Sack, S; Ehmann, A [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

1981-08-01

The compounds Sr/sub 2/Srsub(1/4)Bsub(1/2)sup(III)vacantsub(1/4)WO/sub 6/ equivalent to Sr/sub 8/SrB/sub 2/sup(III)vacantW/sub 4/O/sub 24/ belong to the group of perovskites with octahedral cationic vacancies (cation/vacancy ratio (CN 6) = 7:1). For the larger Bsup(III) ions (La, Pr, Nd, Sm-Dy) different ordering effects are observed. The perovskites with Bsup(III) = Sm, Eu, Gd are polymorphic too (HT modification: higher ordered cubic perovskite (Bsup(III) = Gd: a = 2 x 8.23/sub 4/ A); LT modification: hexagonal perovskite stacking polytype (Bsup(III) = Gd: a = 9.95/sub 4/ A; c = 19.0/sub 4/ A)). With the smaller Bsup(III) ions (Ho, Er, Tm and Y) a cubic, 1:1 ordered perovskite type is observed.

Electro-spray Ionization Mass Spectrometry Investigation of BTBP - Lanthanide(III) and Actinide(III) Complexes

Energy Technology Data Exchange (ETDEWEB)

Retegan, T.; Ekberg, Ch. [Chalmers, Dept Chem and Biol Engn, SE-41296 Gothenburg, (Sweden); Berthon, L.; Zorz, N. [DEN DRCP SCPS LCSE, CEA Marcoule, Bagnols Sur Ceze, (France)

2009-07-01

In the framework of nuclear waste reprocessing, the separation processes of minor actinides from fission products are developed using liquid-liquid extraction. To gain an understanding of the mechanism involved in the extraction process, a complex formation of actinides and lanthanides with BTBPs (6, 6'-bis(5, 6-dialkyl-1, 2, 4-triazin-3-yl)-2, 2'-bipyridines) was characterized using the Electro-spray Ionization Mass Spectrometry (ESI-MS) technique. This study was carried out to compare the influence of diluents and side groups of the extractants on complex formation. Three different diluents, nitrobenzene, octanol and cyclohexanone, and two extractants, C5-BTBP and CyMe{sub 4}-BTBP, were selected for this experiment. It was found that the change of the diluent and of the substituent on the BTBP moiety does not modify the stoichiometry of the complexes which is L{sub 2}M(NO{sub 3}){sub 3}. It is proposed that one nitrate is directly coordinated to the metal ion, the two other anions probably remaining in the outer coordination sphere. The difference observed in extracting properties is probably due to the solvation of the complexes by the diluent. The noncovalent force that holds complexes together are likely to be largely governed by electrostatic interactions even if the hydrophobic exterior of the complexes plays an important role in the complexation/extraction mechanism. The study of the stability of the ions in the gas phase shows that the C5-BTBP ligand has a labile hydrogen atom, which is a fragility point of C5-BTBP. (authors)

Solid-state actinide acid phosphites from phosphorous acid melts

International Nuclear Information System (INIS)

Oh, George N.; Burns, Peter C.

2014-01-01

The reaction of UO 3 and H 3 PO 3 at 100 °C and subsequent reaction with dimethylformamide (DMF) produces crystals of the compound (NH 2 (CH 3 ) 2 )[UO 2 (HPO 2 OH)(HPO 3 )]. This compound crystallizes in space group P2 1 /n and consists of layers of uranyl pentagonal bipyramids that share equatorial vertices with phosphite units, separated by dimethylammonium. In contrast, the reaction of phosphorous acid and actinide oxides at 210 °C produces a viscous syrup. Subsequent dilution in solvents and use of standard solution-state methods results in the crystallization of two polymorphs of the actinide acid phosphites An(HPO 2 OH) 4 (An=U, Th) and of the mixed acid phosphite–phosphite U(HPO 3 )(HPO 2 OH) 2 (H 2 O)·2(H 2 O). α- and β-An(HPO 2 OH) 4 crystallize in space groups C2/c and P2 1 /n, respectively, and comprise a three-dimensional network of An 4+ cations in square antiprismatic coordination corner-sharing with protonated phosphite units, whereas U(HPO 3 )(HPO 2 OH) 2 (H 2 O) 2 ·(H 2 O) crystallizes in a layered structure in space group Pbca that is composed of An 4+ cations in square antiprismatic coordination corner-sharing with protonated phosphites and water ligands. We discuss our findings in using solid inorganic reagents to produce a solution-workable precursor from which solid-state compounds can be crystallized. - Graphical abstract: Reaction of UO 3 and H 3 PO 3 at 100 °C and subsequent reaction with DMF produces crystals of (NH 2 (CH 3 ) 2 )[UO 2 (HPO 2 OH)(HPO 3 )] with a layered structure. Reaction of phosphorous acid and actinide oxides at 210 °C produces a viscous syrup and further solution-state reactions result in the crystallization of the actinide acid phosphites An(HPO 2 OH) 4 (An=U, Th), with a three-dimensional network structure, and the mixed acid phosphite–phosphite U(HPO 3 )(HPO 2 OH) 2 (H 2 O) 2 ·(H 2 O) with a layered structure. - Highlights: • U(VI), U(IV) and Th(IV) phosphites were synthesized by solution

Impact of Eu(III) on mammalian cells as a function of its speciation

Energy Technology Data Exchange (ETDEWEB)

Sachs, Susanne; Heller, Anne; Geipel, Gerhard; Bernhard, Gert [Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology, Bautzner Landstr. 400, 01328 Dresden (Germany)

2014-07-01

In the case of the accidental release of long-lived radionuclides, e.g., actinides, into the environment, knowledge of their behavior in bio-systems is necessary to asses and to prevent radiological and chemical induced adverse health effects. This includes knowledge of the bioavailability and chemo-/radio-toxicity of these elements for/onto cells, which are governed to a large extent by their speciation [1,2]. In order to gain a better process understanding, we study the interaction of trivalent actinides/lanthanides with mammalian cells on a cellular level combining biochemical and analytical methods. Results of these studies can contribute to the estimation of low dose effects and the development of new decontamination strategies. The cellular tolerance of FaDu cells (human squamous cell carcinoma cell line) toward Eu(III) as an analog for trivalent actinides as well as its uptake into the cells has been studied as a function of the Eu(III) concentration and nutrient composition. To differentiate between chemo-toxic and radio-toxic effects of Eu(III), {sup 152}Eu (β{sup -}, ε) was applied as radioactive tracer besides europium with natural isotope composition. The Eu(III) speciation in the cell culture media has been investigated by time-resolved laser-induced fluorescence spectroscopy as well as by solubility studies in combination with ultrafiltration, ultracentrifugation, cation and anion analysis. These results are used to correlate cytotoxicity and uptake of Eu(III) on/into the cells with its chemical speciation in the nutrient. Presently, we are studying the interaction of Eu(III) with NRK-52E cells (rat kidney epithelial-like cells). The results of these studies will be discussed and compared to those obtained with FaDu cells. From the studies with FaDu cells it was concluded that the Eu(III) cytotoxicity onto these cells depends on the Eu(III) concentration and is influenced by its chemical speciation. This was also reported, for instance, for the

Energy Transfer between U(VI) and Eu(III) Ions Adsorbed on a Silica Surface

Energy Technology Data Exchange (ETDEWEB)

Park, K. K.; Cha, W.; Cho, H. R.; Im, H. J.; Jung, E. C.; Song, K. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2011-05-15

Understanding of chemical behavior of actinide in a groundwater flow is important for assessing the possibility of their migration with water flows in a radioactive waste disposal site. Uranium is ubiquitous in the environment and a major actinide in a nuclear fuel cycle. Americium and curium having isotopes of long half life are minor actinides in a spent fuel. If a minor actinide coexists with uranium in a groundwater flow, some interactions between them could be expected such as minor actinide adsorption onto uranium precipitates and competition with each other for an adsorption to a mineral surface site. Eu(III) ion is frequently used as a chemical analogue of Am(III) and Cm(III) ions in a migration chemistry. The luminescent spectra of U(VI) and Eu(III) ions show a dependency on the coordination symmetry around them, and the changes in intensity or bandwidth of spectra can yield valuable information on their local environment. The luminescent lifetime also strongly depends on the coordination environment, and its measurement is valuable in probe studies on micro-heterogeneous systems. The excited U(VI) ion can be quenched through Stern.Volmer process, hydrolysis of excited species, exciplex formation, electron transfer or energy transfer. In case of U(VI)-Eu(III) system, the interaction between two ions can be studied by measuring the effect of Eu(III) ion on the quenching of U(VI) ion luminescence. There are only a few investigations on the interaction between an excited U(VI) ion and a lanthanide(III) ion. In perchlorate solution, the energy transfer to Eu(III) ion occurred only in solutions of pH>3.87. In this study, the quenching of U(VI) luminescence by Eu(III) on a silica surface was measured. The results will be discussed on the basis of a chemical interaction between them

Actinide oxide photodiode and nuclear battery

Energy Technology Data Exchange (ETDEWEB)

Sykora, Milan; Usov, Igor

2017-12-05

Photodiodes and nuclear batteries may utilize actinide oxides, such a uranium oxide. An actinide oxide photodiode may include a first actinide oxide layer and a second actinide oxide layer deposited on the first actinide oxide layer. The first actinide oxide layer may be n-doped or p-doped. The second actinide oxide layer may be p-doped when the first actinide oxide layer is n-doped, and the second actinide oxide layer may be n-doped when the first actinide oxide layer is p-doped. The first actinide oxide layer and the second actinide oxide layer may form a p/n junction therebetween. Photodiodes including actinide oxides are better light absorbers, can be used in thinner films, and are more thermally stable than silicon, germanium, and gallium arsenide.

Thermodynamic Properties of Actinides and Actinide Compounds

Science.gov (United States)

Konings, Rudy J. M.; Morss, Lester R.; Fuger, Jean

The necessity of obtaining accurate thermodynamic quantities for the actinide elements and their compounds was recognized at the outset of the Manhattan Project, when a dedicated team of scientists and engineers initiated the program to exploit nuclear energy for military purposes. Since the end of World War II, both fundamental and applied objectives have motivated a great deal of further study of actinide thermodynamics. This chapter brings together many research papers and critical reviews on this subject. It also seeks to assess, to systematize, and to predict important properties of the actinide elements, ions, and compounds, especially for species in which there is significant interest and for which there is an experimental basis for the prediction.

Sol-gel chemistry applied to the synthesis of polymetallic oxides including actinides reactivity and structure from solution to solid state; Synthese par voie douce d'oxydes polymetalliques incluant des actinides: reactivite et structure de la solution au solide

Energy Technology Data Exchange (ETDEWEB)

Lemonnier, St

2006-02-15

Minor actinides transmutation is studied at present in order to reduce the radiotoxicity of nuclear waste and the assessment of its technical feasibility requires specific designed materials. When considering americium, yttria stabilized zirconia (Am{sup III} YII Zriv)Or{sub x} is among the ceramic phases that one which presents the required physico-chemical properties. An innovative synthesis of this mixed oxide by sol-gel process is reported in this manuscript. The main aim of this work is to adjust the reactivity of the different metallic cations in aqueous media using complexing agent, in order to initiate a favourable interaction for a homogeneous elements repartition in the forming solid phase. The originality of the settled synthesis lies on an in-situ formation of a stable and monodisperse nano-particles dispersion in the presence of acetylacetone. The main reaction mechanisms have been identified: the sol stabilisation results from an original interaction between the three compounds (Zrly, trivalent cations and acetylacetone). The sol corresponds to a structured system at the nanometer scale for which zirconium and trivalent cations are homogeneously dispersed, preliminary to the sol-gel transition. Furthermore, preliminary studies were carried out with a view to developing materials. They have demonstrated that numerous innovative and potential applications can be developed by taking advantage of the direct and controlled formation of the sol and by adapting the sol-gel transition. The most illustrating result is the preparation of a sintered pellet with the composition Am0,13Zro,73Yo,0901,89 using this approach. (author)

Heterogeneous all actinide recycling in LWR all actinide cycle closure concept

International Nuclear Information System (INIS)

Tondinelli, Luciano

1980-01-01

A project for the elimination of transuranium elements (Waste Actinides, WA) by neutron transmutation is developed in a commercial BWR with U-Pu (Fuel Actinides, FA) recycle. The project is based on the All Actinide Cycle Closure concept: 1) closure of the 'back end' of the fuel cycle, U-Pu coprocessing, 2) waste actinide disposal by neutron transmutation. The reactor core consists of Pu-island fuel assemblies containing WAs in target pins. Two parallel reprocessing lines for FAs and WAs are provided. Mass balance, hazard measure, spontaneous activity during 10 recycles are calculated. Conclusions are: the reduction in All Actinide inventory achieved by Heterogeneous All Actinide Recycling is on the order of 83% after 10 recycles. The U235 enrichment needed for a constant end of cycle reactivity decreases for increasing number of recycles after the 4th recycle. A diffusion-burnup calculation of the pin power peak factors in the fuel assembly shows that design limits can be satisfied. A strong effort should be devoted to the solution of the problems related to high values of spontaneous emission by the target pins

Actinides-1981

International Nuclear Information System (INIS)

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

Actinides-1981

Energy Technology Data Exchange (ETDEWEB)

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.

Sol-gel chemistry applied to the synthesis of polymetallic oxides including actinides reactivity and structure from solution to solid state; Synthese par voie douce d'oxydes polymetalliques incluant des actinides: reactivite et structure de la solution au solide

Energy Technology Data Exchange (ETDEWEB)

Lemonnier, St

2006-02-15

Minor actinides transmutation is studied at present in order to reduce the radiotoxicity of nuclear waste and the assessment of its technical feasibility requires specific designed materials. When considering americium, yttria stabilized zirconia (Am{sup III} YII Zriv)Or{sub x} is among the ceramic phases that one which presents the required physico-chemical properties. An innovative synthesis of this mixed oxide by sol-gel process is reported in this manuscript. The main aim of this work is to adjust the reactivity of the different metallic cations in aqueous media using complexing agent, in order to initiate a favourable interaction for a homogeneous elements repartition in the forming solid phase. The originality of the settled synthesis lies on an in-situ formation of a stable and monodisperse nano-particles dispersion in the presence of acetylacetone. The main reaction mechanisms have been identified: the sol stabilisation results from an original interaction between the three compounds (Zrly, trivalent cations and acetylacetone). The sol corresponds to a structured system at the nanometer scale for which zirconium and trivalent cations are homogeneously dispersed, preliminary to the sol-gel transition. Furthermore, preliminary studies were carried out with a view to developing materials. They have demonstrated that numerous innovative and potential applications can be developed by taking advantage of the direct and controlled formation of the sol and by adapting the sol-gel transition. The most illustrating result is the preparation of a sintered pellet with the composition Am0,13Zro,73Yo,0901,89 using this approach. (author)

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

International Nuclear Information System (INIS)

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

1999-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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.

Separation of minor actinides from a genuine MA/LN fraction

International Nuclear Information System (INIS)

Satmark, B.; Courson, O.; Malmbeck, R.; Pagliosa, G.; Romer, K.; Glatz, J.P.

2001-01-01

Separation of the trivalent Minor Actinides (MA), Am and Cm, has been performed from a genuine MA(III) + Ln(III) solution using Bis-Triazine-Pyridine (BTP) as organic extractant. The representative MA/Ln fraction was obtained from a dissolved commercial LWR fuel (45.2 GWd/tM) submitted subsequently too a PUREX process followed by a DIAMEX process. A centrifugal extractor set-up (16-stages), working in a continuous counter-current mode, was used for the liquid-liquid separation. In the nPr-BTP process, feed decontamination factors for Am and Cm above 96 and 65, respectively were achieved. The back-extraction was more efficient for Am (99.1% recovery) than for Cm (97.5%). This experiment, using the Bis-Triazine-Pyridine molecule is the first successful demonstration of the separation of MA from lanthanides in a genuine MA/Ln fraction with a nitric acid concentration of ca. 1 M. It represents an important break through in the difficult field of minor actinide partitioning of high level liquid waste. (author)

Lanthanides and actinides extraction by calixarenes containing CMPO groups

International Nuclear Information System (INIS)

Garcia Carrera, A.

2001-01-01

In the framework of the French program SPIN concerning the radioactive waste management, researches are performed to develop processes allowing the separation of long-lived radioisotopes in order to their transmutation or their specific conditioning. These studies deal with the extraction and the separation of trivalent lanthanides and actinides in acid solution. Many systems ''calixarene-diluent-aqueous phase'' are examined by extraction liquid-liquid and membrane transport. The extraction efficiency and the selectivity of the synthesized calixarene-CMPO and of the CMPO are compared with these cations, as the nitric acid extraction by these molecules. (A.L.B.)

New strategies in actinide separation - water-soluble complexing agents for the innovative SANEX process

International Nuclear Information System (INIS)

Ruff, Christian M.; Muelllich, Udo; Geist, Andreas; Panak, Petra J.

2012-01-01

Reduction of the radiotoxicity and thermal output of radioactive wastes prior to their permanent disposal is a topic of extreme interest for the issue of final nuclear waste disposal. One possibility to this end is a process referred to as actinide separation. This process can be optimised by means of a newly developed water-soluble molecule, as has been shown in studies on the molecule's complex chemistry using ultra-modern laser-based spectroscopy methods under process-relevant reaction conditions. Through the use of curium (III) and europium (III), which as members of the trivalent actinides and lanthanides family have excellent spectroscopic properties, it has been possible to generate spectroscopic and thermodynamic data which will facilitate our understanding of the complex chemistry and extraction chemistry of this molecule family.

The reprocessing-recycling of spent nuclear fuel. Actinides separation - Application to wastes management; Le traitement-recyclage du combustible nucleaire use. La separation des actinides - Application a la gestion des dechets

Energy Technology Data Exchange (ETDEWEB)

NONE

2008-07-01

After its use in the reactor, the spent fuel still contains lot of recoverable material for an energetic use (uranium, plutonium), but also fission products and minor actinides which represent the residues of nuclear reactions. The reprocessing-recycling of the spent fuel, as it is performed in France, implies the chemical separation of these materials. The development and the industrial implementation of this separation process represent a major contribution of the French science and technology. The reprocessing-recycling allows a good management of nuclear wastes and a significant saving of fissile materials. With the recent spectacular rise of uranium prices, this process will become indispensable with the development of the next generation of fast neutron reactors. This book takes stock of the present and future variants of the chemical process used for the reprocessing of spent fuels. It describes the researches in progress and presents the stakes and recent results obtained by the CEA. content: the separation of actinides, a key factor for a sustainable nuclear energy; the actinides, a discovery of the 20. century; the radionuclides in nuclear fuels; the aquo ions of actinides; some redox properties of actinides; some complexing properties of actinide cations; general considerations about treatment processes; some characteristics of nuclear fuels in relation with their reprocessing; technical goals and specific constraints of the PUREX process; front-end operations of the PUREX process; separation and purification operations of the PUREX process; elaboration of finite products in the framework of the PUREX process; management and treatment of liquid effluents; solid wastes of the PUREX process; towards a joint management of uranium and plutonium: the COEX{sup TM} process; technical options of treatment and recycling techniques; the fuels of generation IV reactors; front-end treatment processes of advanced fuels; hydrometallurgical processes for future fuel

Lanthanides and actinides extraction by calixarenes containing CMPO groups; Extraction des lanthanides et des actinides au moyen de calixarenes portant des groupements CMPO

Energy Technology Data Exchange (ETDEWEB)

Garcia Carrera, A

2001-07-01

In the framework of the French program SPIN concerning the radioactive waste management, researches are performed to develop processes allowing the separation of long-lived radioisotopes in order to their transmutation or their specific conditioning. These studies deal with the extraction and the separation of trivalent lanthanides and actinides in acid solution. Many systems ''calixarene-diluent-aqueous phase'' are examined by extraction liquid-liquid and membrane transport. The extraction efficiency and the selectivity of the synthesized calixarene-CMPO and of the CMPO are compared with these cations, as the nitric acid extraction by these molecules. (A.L.B.)

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

International Nuclear Information System (INIS)

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

1999-01-01

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)

The reprocessing-recycling of spent nuclear fuel. Actinides separation - Application to wastes management

International Nuclear Information System (INIS)

2008-01-01

After its use in the reactor, the spent fuel still contains lot of recoverable material for an energetic use (uranium, plutonium), but also fission products and minor actinides which represent the residues of nuclear reactions. The reprocessing-recycling of the spent fuel, as it is performed in France, implies the chemical separation of these materials. The development and the industrial implementation of this separation process represent a major contribution of the French science and technology. The reprocessing-recycling allows a good management of nuclear wastes and a significant saving of fissile materials. With the recent spectacular rise of uranium prices, this process will become indispensable with the development of the next generation of fast neutron reactors. This book takes stock of the present and future variants of the chemical process used for the reprocessing of spent fuels. It describes the researches in progress and presents the stakes and recent results obtained by the CEA. content: the separation of actinides, a key factor for a sustainable nuclear energy; the actinides, a discovery of the 20. century; the radionuclides in nuclear fuels; the aquo ions of actinides; some redox properties of actinides; some complexing properties of actinide cations; general considerations about treatment processes; some characteristics of nuclear fuels in relation with their reprocessing; technical goals and specific constraints of the PUREX process; front-end operations of the PUREX process; separation and purification operations of the PUREX process; elaboration of finite products in the framework of the PUREX process; management and treatment of liquid effluents; solid wastes of the PUREX process; towards a joint management of uranium and plutonium: the COEX TM process; technical options of treatment and recycling techniques; the fuels of generation IV reactors; front-end treatment processes of advanced fuels; hydrometallurgical processes for future fuel cycles

Actinide colloid generation in groundwater

International Nuclear Information System (INIS)

Kim, J.I.

1990-05-01

The progress made in the investigation of actinide colloid generation in groundwaters is summarized and discussed with particular examples relevant to an understanding of the migration behaviour of actinides in natural aquifer systems. The first part deals with the characterization of colloids: groundwater colloids, actinide real-colloids and actinide pseudocolloids. The second part concentrates on the generation processes and migration behaviour of actinide pseudocolloids, which are discussed with some notable experimental examples. Importance is stressed more on the chemical aspects of the actinide colloid generation in groundwater. This work is a contribution to the CEC project MIRAGE II, particularly, to research area: complexation and colloids. (orig.)

Study of the chemical interactions of actinide cations in solution at macroscopic concentrations

International Nuclear Information System (INIS)

Maurice, C.

1983-01-01

The aim of this work was to study the interactions of pentavalent neptunium in dodecane-diluted tributyl phosphate with other metallic cations, especially uranium VI and ruthenium present in reprocessing solutions. Pentavalent neptunium on its own was shown to exist in several forms complexed by water and TBP and also to dimerise. In the complex it forms with uranium VI the interaction via the neptunyl oxygen is considerably enhanced in organic solution. Dibutyl phosphoric acid strengthens the interaction between neptunium and uranium. The Np V-ruthenium interaction reveals the existence of a new cation-cation complex; the process takes place in two successive stage and leads to the formation, reinforced and accelerated by HDBP, of a highly to the formation, reinforced and accelerated by HDBP, of a highly stable complex. These results contribute towards a better knowledge of the behaviour of neptunium in the reprocessing operation [fr

Demonstration of innovative partitioning processes for minor actinide recycling from high active waste solutions

International Nuclear Information System (INIS)

Modolo, G.; Wilden, A.; Geist, A.; Malmbeck, R.; Taylor, R.

2014-01-01

The recycling of the minor actinides (MA) using the Partitioning and Transmutation strategy (P and T) could contribute significantly to reducing the volume of high level waste in a geological repository and to decreasing the waste's longterm hazards originating from the long half-life of the actinides. Several extraction processes have been developed worldwide for the separation and recovery of MA from highly active raffinates (HAR, e.g. the PUREX raffinate). A multi-cycle separation strategy has been developed within the framework of European collaborative projects. The multi-cycle processes, on the one hand, make use of different extractants for every single process. Within the recent FP7 European research project ACSEPT (Actinide reCycling by SEParation and Transmutation), the development of new innovative separation processes with a reduced number of cycles was envisaged. In the so-called 'innovative SANEX' concept, the trivalent actinides and lanthanides are co-extracted from the PUREX raffinate by a DIAMEX like process (e.g. TODGA). Then, the loaded solvent is subjected to several stripping steps. The first one concerns selectively stripping the actinides(III) with selective water-soluble ligands (SO3-Ph-BTB), followed by the subsequent stripping of trivalent lanthanides. A more challenging route studied also within our laboratories is the direct actinide(III) separation from a PUREX-type raffinate using a mixture of CyMe 4 BTBP and TODGA as extractants, the so-called One cycle SANEX process. A new approach, which was also studied within the ACSEPT project, is the GANEX (Grouped ActiNide EXtraction) concept addressing the simultaneous partitioning of all transuranium (TRU) elements for their homogeneous recycling in advanced generation IV reactor systems. Bulk uranium is removed in the GANEX 1st cycle, e.g. using a monoamide extractant and the GANEX 2nd cycle then separates the TRU. A solvent composed of TODGA + DMDOHEMA in kerosene has been shown to

Preparation of minor actinides targets or blankets by the means of Ionic Exchange Resin

Energy Technology Data Exchange (ETDEWEB)

Picart, S.; Mokhtari, H.; Ramiere, I.; Jobelin, I. [CEA, Nuclear Energy Division, RadioChemistry and Process Department, Actinides Chemistry Laboratory, BP17171, Bagnols-sur-Ceze, 30207 (France)

2009-06-15

The objective of our R and D work is the elaboration by the use of ionic exchange resin of minor actinide precursors for target or blanket dedicated to their transmutation in sodium fast reactor. From the beginning, the resin process called WAR (acronym of Weak Acid Resin) was developed in the 70's at the ORNL for the making of uranium carbide kernels for the high temperature gas reactor [1] [2]. By now, our aim is to extend this concept to the manufacturing of minor actinides oxide mixed with uranium oxides [3]. More precisely, this process can be divided in two major steps: the loading of the resin and the thermal treatment of the fully loaded resin driving either to oxide or carbide phases depending on the gas atmosphere. The difficulty stems from the preparation of the loading solutions which must fulfill precise conditions of pH in presence of actinides cations prone to hydrolysis. Furthermore, the proportions of uranium and minor actinides in solutions must be adjusted to fit the right ratio in the solid. The study presented here will then focus on the experiments and tests which enable us to optimize the fixing of minor actinides on ionic exchange resin and their carbonization in oxide. [1] G. W. Weber, R. L. Beatty et V. J. Tennery, Nuclear Technology, 35, 217-226, (1977), 'Processing and composition control of weak-acid-resin derived fuel microspheres'. [2] K. J. Notz, P. A. Haas, J. H. Shaffer, Radiochimica Acta, 25, 153-160, (1978). 'The preparation of HTGR Fissile Fuel Kernels by Uranium Loading of Ion Exchange Resin'. [3] S. Picart, H. Mokhtari, I. Ramiere, 'Plutonium Futures, The Science 2008', 7-11 july 2008, Dijon, France. 'Modelling of the ionic Exchange between a weak acid resin in its ammonium form and a minor actinide'. (authors)

Research in actinide chemistry

International Nuclear Information System (INIS)

Choppin, G.R.

1993-01-01

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 - , CO 3 2- , PO 4 3- , humates). The research undertakes fundamental studies of actinide complexes which can increase understanding of the environmental behavior of these elements

Actinide oxides synthesis in molten chloride. Structural studies and reaction mechanisms

International Nuclear Information System (INIS)

Vigier, J.F.

2012-01-01

Pyrochemical processes are studied as potential alternatives to hydrochemical processes for spent nuclear fuel treatment. The CEA pyrochemical process led to a molten LiCl-CaCl 2 (30-70% mol) salt at 700 C with solubilized actinides at the oxidation state (III). The study developed in this thesis concerns actinide oxides synthesis in this media for nuclear fuel re-fabrication. This synthesis was done by wet argon sparging. First, this conversion method is described for neodymium (III) and cerium (III) co-conversion. The conversion rates are around 99.9%. The obtained powders contain mixed oxychloride Ce 1-x Nd x OCl as main component, with a small amount of mixed oxide Ce 1-x Nd x O 2-0,5x for the high cerium ratio. A second oxychloride CeIV(Nd 0.7 Ce 0.3 ) III O 3 Cl is obtained in specific conditions and in very low quantity. The structure of this oxychloride is described in this study. The partially oxidative property of the conversion method induces the oxidation of a part of cerium (III) to oxidation state (IV). In the case of uranium (III) conversion by wet argon sparging, all the uranium is oxidized and give the oxide UO 2 as single compound. The conversion rate for this element is over 99.9% in the molten chloride, but significant amount of uranium is lost by volatilization during the conversion. The study shows the oxygen sensitivity of uranium during the conversion, inducing oxidation over the oxidation state (IV), and giving UO 2+x or uranate CaUO 4 . As a consequence, oxygen led to calcium pollution in the precipitate. Finally, the U(III) and Pu(III) co-conversion study shows the highest precipitation sensitivity of uranium (III) in comparison with plutonium (III), responsible of a successive conversion of the two elements, giving an oxide mixture of UO 2 et PuO 2 with quantitative conversion rate. Surprisingly, the conversion of Pu(III) in the same conditions led to a mixture of PuO 2 and PuOCl, characteristic of a partial oxidation from Pu (III) to Pu

Recovery of actinides from actinide-aluminium alloys by chlorination: Part I

Energy Technology Data Exchange (ETDEWEB)

Cassayre, L., E-mail: cassayre@chimie.ups-tlse.fr [Laboratoire de Genie Chimique (LGC), Departement Procedes Electrochimiques, CNRS-UMR 5503, Universite de Toulouse III - Paul Sabatier, 31062 Toulouse (France); Soucek, P.; Mendes, E.; Malmbeck, R.; Nourry, C.; Eloirdi, R.; Glatz, J.-P. [European Commission, JRC, Institute for Transuranium Elements, Postfach 2340, 76125 Karlsruhe (Germany)

2011-07-01

Pyrochemical processes in molten LiCl-KCl are being developed in ITU for recovery of actinides from spent nuclear fuel. The fuel is anodically dissolved to the molten salt electrolyte and actinides are electrochemically reduced on solid aluminium cathodes forming solid actinide-aluminium alloys. A chlorination route is being investigated for recovery of actinides from the alloys. This route consists in three steps: Vacuum distillation for removal of the salt adhered on the electrode, chlorination of the actinide-aluminium alloys by chlorine gas and sublimation of the formed AlCl{sub 3}. A thermochemical study showed thermodynamic feasibility of all three steps. On the basis of the conditions identified by the calculations, experiments using pure UAl{sub 3} alloy were carried out to evaluate and optimise the chlorination step. The work was focused on determination of the optimal temperature and Cl{sub 2}/UAl{sub 3} molar ratio, providing complete chlorination of the alloy without formation of volatile UCl{sub 5} and UCl{sub 6}. The results showed high efficient chlorination at a temperature of 150 deg. C.

Recovery of actinides from actinide-aluminium alloys by chlorination: Part I

International Nuclear Information System (INIS)

Cassayre, L.; Soucek, P.; Mendes, E.; Malmbeck, R.; Nourry, C.; Eloirdi, R.; Glatz, J.-P.

2011-01-01

Pyrochemical processes in molten LiCl-KCl are being developed in ITU for recovery of actinides from spent nuclear fuel. The fuel is anodically dissolved to the molten salt electrolyte and actinides are electrochemically reduced on solid aluminium cathodes forming solid actinide-aluminium alloys. A chlorination route is being investigated for recovery of actinides from the alloys. This route consists in three steps: Vacuum distillation for removal of the salt adhered on the electrode, chlorination of the actinide-aluminium alloys by chlorine gas and sublimation of the formed AlCl 3 . A thermochemical study showed thermodynamic feasibility of all three steps. On the basis of the conditions identified by the calculations, experiments using pure UAl 3 alloy were carried out to evaluate and optimise the chlorination step. The work was focused on determination of the optimal temperature and Cl 2 /UAl 3 molar ratio, providing complete chlorination of the alloy without formation of volatile UCl 5 and UCl 6 . The results showed high efficient chlorination at a temperature of 150 deg. C.

Leaching of irradiated polymers: solution characterization and actinides complexation

International Nuclear Information System (INIS)

Fromentin, Elodie

2017-01-01

The first aim of this work is to study the degradation of an industrial poly-esterurethane (PURm) by radio-oxidation and then by leaching in an alkaline aqueous solution. The second aim is to measure the complexing power of hydro-soluble degradation products (HDP) with actinides. To reach these goals, PURm was first characterized and then radio-oxidized at room temperature with γ rays up to 10 MGy. Second, it was leached at pH 13.3 at different temperature values. Numerous analytical techniques were employed in order to characterize the HDP which were obtained. Europium(III) was used as an analogue of actinides(III) and the behavior of HDP with europium(III) was analyzed by time-resolved luminescence spectroscopy (TRLS). Whatever the dose received by PURm, adipic acid and butane-1,4-diol are the two main HDP in leachates. The leaching data acquired at 40 and 60 C, on the 1 MGy radio-oxidized PURm, correlate with the model given by Yoon et al. (1997). However, the data at room temperature (22 C in average) are not in agreement with the model. Nevertheless, it seems that the plateau which was reached at long-term leaching is the same whatever the temperature used in this study. The results allow to conclude that the predominant mechanism occurring during the leaching of unirradiated and radio-oxidized PURm in an alkaline medium is the hydrolysis of the soft segments ester groups. The complexation of europium(III) by HDP in alkaline medium was demonstrated. The measurement of the complexing power and the identification of ligands was achieved under certain conditions. (author) [fr

New strategy for minor actinides partitioning preliminary results on the electrovolatilization of ruthenium and on the stabilization of Am(IV) in nitric acid with phosphotunsgstate ligand

International Nuclear Information System (INIS)

Adnet, J.M.; Madic, C.

1989-01-01

On problems related to the long term storage in deep geological repositories of high active wastes (H.A.W.) is due to the presence of minor actinide isotopes. Thus after the decay of the fission products (≅ 300 years) the toxicity of these H.A.W. is mainly due to the minor actinides. One solution is based on actinide partitioning followed by transmutation into fission products with short half-lives. A simpler processes than those developed previously, can be based on the possible oxidation of minor actinides to the + IV or + VI oxidation states and their selective extraction. The first step to study is the elimination of the ruthenium (whose presence would be detrimental to oxidize minor actinides) which can be done by electrovolatilization of Ru on the RuO 4 form. The rate of electrovolatilization can be increased by the use of the following electronic mediators, AgI/AgII(1); CeIII/Ce(2), and CoII/CoIII(3), the efficiency of which decreases in the order: 1 > 2 > 3. The effectiveness of that process has been proven when treating real H.A.W solution produced during the study of the reprocessing of a MOX fuel irradiated to as burn-up of 52 GWd/t in a LWR: complete Ru removal was obtained. The second part of the study concerns the electrochemical oxidation of AmIII in nitric acid solutions in the presence of a strong complexing agent: P 2 W 17 O 61 K 10 (P.W.).Total americium oxidation to AmIV can be obtained in nitric acid solution with a concentration up to 8 M. No particular drawback was induced by the presence of an amount of lanthanide III (NdIII) in 6 fold excess vs P.W. The stability of AmIV was studied. The other actinides will be present in these solutions, after the electrochemical oxidation step, in the + VI or+ IV oxidation states, thus a selective extraction (vs fission products) could be performed. A possible way to extract actinide IV/P.W complexes is to use dodecylamine nitrate as extractant

X-ray absorption spectroscopic study of trivalent and tetravalent actinides in solution at varying pH values

Energy Technology Data Exchange (ETDEWEB)

Brendebach, B.; Banik, N.L.; Marquardt, C.M.; Rothe, J.; Denecke, M.A.; Geckeis, H. [Forschungszentrum Karlsruhe (Germany). Inst. fuer Nukleare Entsorgung

2009-07-01

We perform X-ray absorption spectroscopy (XAS) investigations to monitor the stabilization of redox sensitive trivalent and tetravalent actinide ions in solution at acidic conditions in a pH range from 0 to 3 after treatment with holding reductants, hydroxylamine hydrochloride (NH{sub 2}OHHCl) and Rongalite (sodium hydroxymethanesulfinate, CH{sub 3}NaO{sub 3}S). X-ray absorption near edge structure (XANES) measurements clearly demonstrate the stability of the actinide species for several hours under the given experimental conditions. Hence, structural parameters can be accurately derived by extended X-ray absorption fine structure (EXAFS) investigations. The coordination structure of oxygen atoms belonging to water ligands surrounding the actinide ions does not change with increasing pH value (approximately 11 O atoms at 2.42 A in the case of U(IV) at pH 1, 9 0 atoms at 2.52 A for Np(III) at pH 1.5, and 10 O atoms at 2.49 A for Pu(III) up to pH 3), indicating that hydrolysis reactions are suppressed under the given chemical conditions. (orig.)

Study of interactions between lanthanides/actinides and humic substances by a steric exclusion chromatographic method

International Nuclear Information System (INIS)

Moulin, V.

1986-01-01

The knowledge of cation-humic matter interactions has a great importance in order to have a better understanding of the contribution of these substances to the possible transport of radioactive elements in the geosphere via groundwaters. The method chosen to study the formation of soluble species between lanthanides/actinides ions and humic acids from different origins is a chromatographic technique of gel filtration. This dynamic equilibrium method is based on the separation of the formed complex and the free cation by the porous packing gel. Different elements have been studied by this method: UO 2 2+ , Eu 3+ , Th 4+ and global interaction constants have been calculated. The application to transuranic elements is undertaken. (orig.)

Synthesis and characterisation of nitrogen poly-heterocyclic molecules using as selective complexing agents of metallic cations; Synthese et caracterisation de molecules polyheterocycliques azotees utilisables en tant que complexants selectifs de cations metalliques

Energy Technology Data Exchange (ETDEWEB)

Alphonse, F.A

2003-12-15

Separation of actinides (III) from lanthanides (III) is a crucial problem in the reprocessing of used nuclear fuels. Experimental results shown that soft donor extractants such as nitrogen polydentate heterocycles containing a NCCNCCN coordination site are potentials ligands for selective extraction of actinides (III). In those cases, two types of liquid-liquid extractions are employed: synergistic combination with lipophilic acid extractants and direct extraction. On the basis of the Hard and Soft Acids and Bases theory and basicity evaluation, new extractants were defined. We have first studied the synthesis of potential 1,3,5-triazine ligands designed for extraction in synergy with {alpha}-bromodecanoic acid. Secondly, we have examined the synthesis of bis-triazinyl-pyridine ligands for direct extraction studies. Extraction tests were carried out and perspectives of synthesis were deducted from those extraction results. (author)

Actinides

International Nuclear Information System (INIS)

Martinot, L.; Fuger, J.

1985-01-01

The oxidation behavior of the actinides is explained on the basis of their electronic structure. The actinide elements, actinium, thorium, protactinium, uranium, neptunium, plutonium, americium, curium, berkelium, californium, einsteinium, fermium, mendelevium, nobelium, and laurencium are included. For all except the last three elements, the points of discussion are oxidation states, Gibbs energies and potentials, and potential diagram for the element in acid solution; and thermodynamic properties of these same elements are tabulated. References are cited following discussion of each element with a total of 97 references being cited. 13 tables

A review of the demonstration of innovative solvent extraction processes for the recovery of trivalent minor actinides from PUREX raffinate

International Nuclear Information System (INIS)

Modolo, G.; Wilden, A.; Geist, A.; Magnusson, D.; Malmbeck, R.

2012-01-01

The selective partitioning (P) of long-lived minor actinides from highly active waste solutions and their transmutation (T) to short-lived or stable isotopes by nuclear reactions will reduce the long-term hazard of the high-level waste and significantly shorten the time needed to ensure their safe confinement in a repository. The present paper summarizes the on-going research activities at Forschungszentrum Juelich (FZJ), Karlsruher Institut fuer Technologie (KIT) and Institute for Transuranium Elements (ITU) in the field of actinide partitioning using innovative solvent extraction processes. European research over the last few decades, i.e. in the NEWPART, PARTNEW and EUROPART programmes, has resulted in the development of multi-cycle processes for minor actinide partitioning. These multi-cycle processes are based on the co-separation of trivalent actinides and lanthanides (e.g. by the DIAMEX process), followed by the subsequent actinide(III)/lanthanide(III) group separation in the SANEX process. The current direction of research for the development of innovative processes within the recent European ACSEPT project is discussed additionally. This paper is focused on the development of flow-sheets for recovery of americium and curium from highly active waste solutions. The flow-sheets are verified by demonstration processes, in centrifugal contactors, using synthetic or genuine fuel solutions. The feasibility of the processes is also discussed. (orig.)

A uranium-based UO_2"+-Mn"2"+ single-chain magnet assembled trough cation-cation interactions

International Nuclear Information System (INIS)

Mougel, Victor; Chatelain, Lucile; Hermle, Johannes; Pecaut, Jacques; Mazzanti, Marinella; Caciuffo, Roberto; Colineau, Eric; Tuna, Floriana; Magnani, Nicola; Geyer, Arnaud de

2014-01-01

Single-chain magnets (SCMs) are materials composed of magnetically isolated one-dimensional (1D) units exhibiting slow relaxation of magnetization. The occurrence of SCM behavior requires the fulfillment of stringent conditions for exchange and anisotropy interactions. Herein, we report the synthesis, the structure, and the magnetic characterization of the first actinide-containing SCM. The 5f-3d heterometallic 1D chains [{[UO_2(salen)(py)][M(py)_4](NO_3)}]_n, (M=Cd (1) and M=Mn (2); py=pyridine) are assembled trough cation-cation interaction from the reaction of the uranyl(V) complex [UO_2(salen)py][Cp"*_2Co] (Cp"*=pentamethylcyclopentadienyl) with Cd(NO_3)_2 or Mn(NO_3)_2 in pyridine. The infinite UMn chain displays a high relaxation barrier of 134±0.8 K (93±0.5 cm"-"1), probably as a result of strong intra-chain magnetic interactions combined with the high Ising anisotropy of the uranyl(V) dioxo group. It also exhibits an open magnetic hysteresis loop at T<6 K, with an impressive coercive field of 3.4 T at 2 K.

Sol-gel chemistry applied to the synthesis of polymetallic oxides including actinides reactivity and structure from solution to solid state

International Nuclear Information System (INIS)

Lemonnier, St.

2006-02-01

Minor actinides transmutation is studied at present in order to reduce the radiotoxicity of nuclear waste and the assessment of its technical feasibility requires specific designed materials. When considering americium, yttria stabilized zirconia (Am III YII Zriv)Or x is among the ceramic phases that one which presents the required physico-chemical properties. An innovative synthesis of this mixed oxide by sol-gel process is reported in this manuscript. The main aim of this work is to adjust the reactivity of the different metallic cations in aqueous media using complexing agent, in order to initiate a favourable interaction for a homogeneous elements repartition in the forming solid phase. The originality of the settled synthesis lies on an in-situ formation of a stable and monodisperse nano-particles dispersion in the presence of acetylacetone. The main reaction mechanisms have been identified: the sol stabilisation results from an original interaction between the three compounds (Zrly, trivalent cations and acetylacetone). The sol corresponds to a structured system at the nanometer scale for which zirconium and trivalent cations are homogeneously dispersed, preliminary to the sol-gel transition. Furthermore, preliminary studies were carried out with a view to developing materials. They have demonstrated that numerous innovative and potential applications can be developed by taking advantage of the direct and controlled formation of the sol and by adapting the sol-gel transition. The most illustrating result is the preparation of a sintered pellet with the composition Am0,13Zro,73Yo,0901,89 using this approach. (author)

Speciation of actinides in aqueous solution by time-resolved laser-induced fluorescence spectroscopy (TRLFS)

International Nuclear Information System (INIS)

Kimura, Takaumi; Kato, Yoshiharu; Meinrath, G.; Yoshida, Zenko; Choppin, G.R.

1995-01-01

Time-resolved laser-induced fluorescence spectroscopy (TRLFS) as a sensitive and selective method has been applied to the speciation of actinides in aqueous solution. Studies on hydrolysis and carbonate complexation of U(VI) and on determination of hydration number of Cm(III) are reported. (author)

Actinide recycle

Energy Technology Data Exchange (ETDEWEB)

Till, C; Chang, Y [Argonne National Laboratory, Argonne, IL (United States)

1990-07-01

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.

Actinide recycle

International Nuclear Information System (INIS)

Till, C.; Chang, Y.

1990-01-01

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

Lanthanide and actinide ion phytoextraction: investigations of biosorption chemistry

International Nuclear Information System (INIS)

Rayson, Gary D.; Serna, Debbie D.; Moore, Jessica L.

2009-01-01

Investigations of the chemical interactions responsible for passive biosorption of a lanthanide (Eu (III)) and an actinide (U (VI)) metal ion is described. Spectroscopic methods for the elucidation of chemical functionalities on cultured anther cell walls from the plant Datura innoxia include metal ion luminescence measurements. These have revealed the presence of distinctly different binding environments involving one, two, and three carboxylate moieties for Eu (III) and UO 2 2+ binding and sulfonates (or sulfates) and phosphates for sequestration of Eu (III) on the uranyl ion, respectively. Additional investigations of the apparent affinities of these metals to this material have revealed the presence of both low and high affinity sites for the binding of Eu (III) with weak electrostatic attractions proposed for binding at high metal concentrations (i.e., low affinities) and surface coordination interactions responsible for higher affinities. Conversely, total uranyl ion binding revealed only a single distribution of interactions based on apparent affinities. (author)

Actinide, lanthanide and fission product speciation and electrochemistry in high and low temperature ionic melts

Energy Technology Data Exchange (ETDEWEB)

Bhatt, Anand I.; Kinoshita, Hajime; Koster, Anne L.; May, Iain; Sharrad, Clint A.; Volkovich, Vladimir A.; Fox, O. Danny; Jones, Chris J.; Lewin, Bob G.; Charnock, John M.; Hennig, Christoph

2004-07-01

There is currently a great deal of research interest in the development of molten salt technology, both classical high temperature melts and low temperature ionic liquids, for the electrochemical separation of the actinides from spent nuclear fuel. We are interested in gaining a better understanding of actinide and key fission product speciation and electrochemical properties in a range of melts. Our studies in high temperature alkali metal melts (including LiCl and LiCl-KCl and CsCl-NaCl eutectics) have focussed on in-situ species of U, Th, Tc and Ru using X-ray absorption spectroscopy (XAS, both EXAFS and XANES) and electronic absorption spectroscopy (EAS). We report unusual actinide speciation in high temperature melts and an evaluation of the likelihood of Ru or Tc volatilization during plant operation. Our studies in lower temperature melts (ionic liquids) have focussed on salts containing tertiary alkyl group 15 cations and the bis(tri-fluor-methyl)sulfonyl)imide anion, melts which we have shown to have exceptionally wide electrochemical windows. We report Ln, Th, U and Np speciation (XAS, EAS and vibrational spectroscopy) and electrochemistry in these melts and relate the solution studies to crystallographic characterised benchmark species. (authors)

Actinide, lanthanide and fission product speciation and electrochemistry in high and low temperature ionic melts

International Nuclear Information System (INIS)

Bhatt, Anand I.; Kinoshita, Hajime; Koster, Anne L.; May, Iain; Sharrad, Clint A.; Volkovich, Vladimir A.; Fox, O. Danny; Jones, Chris J.; Lewin, Bob G.; Charnock, John M.; Hennig, Christoph

2004-01-01

There is currently a great deal of research interest in the development of molten salt technology, both classical high temperature melts and low temperature ionic liquids, for the electrochemical separation of the actinides from spent nuclear fuel. We are interested in gaining a better understanding of actinide and key fission product speciation and electrochemical properties in a range of melts. Our studies in high temperature alkali metal melts (including LiCl and LiCl-KCl and CsCl-NaCl eutectics) have focussed on in-situ species of U, Th, Tc and Ru using X-ray absorption spectroscopy (XAS, both EXAFS and XANES) and electronic absorption spectroscopy (EAS). We report unusual actinide speciation in high temperature melts and an evaluation of the likelihood of Ru or Tc volatilization during plant operation. Our studies in lower temperature melts (ionic liquids) have focussed on salts containing tertiary alkyl group 15 cations and the bis(tri-fluor-methyl)sulfonyl)imide anion, melts which we have shown to have exceptionally wide electrochemical windows. We report Ln, Th, U and Np speciation (XAS, EAS and vibrational spectroscopy) and electrochemistry in these melts and relate the solution studies to crystallographic characterised benchmark species. (authors)

Selective Media for Actinide Collection and Pre-Concentration: Results of FY 2006 Studies

Energy Technology Data Exchange (ETDEWEB)

Lumetta, Gregg J.; Addleman, Raymond S.; Hay, Benjamin P.; Hubler, Timothy L.; Levitskaia, Tatiana G.; Sinkov, Sergey I.; Snow, Lanee A.; Warner, Marvin G.; Latesky, Stanley L.

2006-11-17

In this work, we have investigated new materials for potential use in automated radiochemical separations. The work can be divided into three primary tasks: (1) synthesis of new ligands with high affinity for actinide ions, (2) evaluation of new materials for actinide ion affinity, and (3) computational design of advanced ligand architectures for highly selective binding of actinide ions. Ligand Synthesis Work was conducted on synthesizing Kl?ui ligand derivatives containing functionalized pendant groups on the cyclopentadienyl ring. The functionalized pendent groups would allow these ligands to be attached to organic and inorganic solid supports. This work focused on synthesizing the compound Na[Cp?Co(PO(OC2H5)2)3], where Cp?= C5H4C(O)OCH3. Synthesizing this compound is feasible, but the method used in FY 2006 produced an impure material. A modified synthetic scheme has been developed and will be pursued in FY 2007. Work was also initiated on synthesizing bicyclic diamides functionalized for binding to polymeric resins or other surfaces. Researchers at the University of Oregon are collaborators in this work. To date, this effort has focused on synthesizing and characterizing a symmetrically substituted bicyclic diamide ligand with the ?COOH functionality. Again, this synthetic effort will continue into FY 2007. Separations Material Evaluation Work was conducted in FY 2006 to provide a more extensive set of data on the selectivity and affinity of extraction chromatography resins prepared by sorption of Kl?ui ligand onto an inert macroreticular polymeric support. Consistent with previous observations, it was found that these materials strongly bind tetravalent actinides. These materials also adsorb trivalent actinides at low nitric acid concentrations, but the affinity for the trivalent actinides decreases with increasing nitric acid concentration. These materials have relatively low affinity for U(VI), but they do sorb U(VI) to a greater extent than Am(III) at [HNO

Selective Media for Actinide Collection and Pre-Concentration: Results of FY 2006 Studies

International Nuclear Information System (INIS)

Lumetta, Gregg J.; Addleman, Raymond S.; Hay, Benjamin P.; Hubler, Timothy L.; Levitskaia, Tatiana G.; Sinkov, Sergey I.; Snow, Lanee A.; Warner, Marvin G.; Latesky, Stanley L.

2006-01-01

In this work, we have investigated new materials for potential use in automated radiochemical separations. The work can be divided into three primary tasks: (1) synthesis of new ligands with high affinity for actinide ions, (2) evaluation of new materials for actinide ion affinity, and (3) computational design of advanced ligand architectures for highly selective binding of actinide ions. Ligand Synthesis Work was conducted on synthesizing Kl?ui ligand derivatives containing functionalized pendant groups on the cyclopentadienyl ring. The functionalized pendent groups would allow these ligands to be attached to organic and inorganic solid supports. This work focused on synthesizing the compound Na[Cp?Co(PO(OC2H5)2)3], where Cp?C5H4C(O)OCH3. Synthesizing this compound is feasible, but the method used in FY 2006 produced an impure material. A modified synthetic scheme has been developed and will be pursued in FY 2007. Work was also initiated on synthesizing bicyclic diamides functionalized for binding to polymeric resins or other surfaces. Researchers at the University of Oregon are collaborators in this work. To date, this effort has focused on synthesizing and characterizing a symmetrically substituted bicyclic diamide ligand with the ?COOH functionality. Again, this synthetic effort will continue into FY 2007. Separations Material Evaluation Work was conducted in FY 2006 to provide a more extensive set of data on the selectivity and affinity of extraction chromatography resins prepared by sorption of Kl?ui ligand onto an inert macroreticular polymeric support. Consistent with previous observations, it was found that these materials strongly bind tetravalent actinides. These materials also adsorb trivalent actinides at low nitric acid concentrations, but the affinity for the trivalent actinides decreases with increasing nitric acid concentration. These materials have relatively low affinity for U(VI), but they do sorb U(VI) to a greater extent than Am(III) at [HNO3

Monazite-type ceramics for the immobilization of minor actinides plutonium

International Nuclear Information System (INIS)

Heuser, Julia Maria

2015-01-01

The safe disposal of radioactive waste in deep geological formations is a challenging task of present and future generations. Innovative strategies as the conditioning of radionuclides in ceramic matrices can make a contribution here. This work points out monazite-type ceramics as potential waste forms for minor actinides and Pu. Several aspects concerning nuclear disposal as well as fundamental structural information were investigated. Lanthanide phosphate endmembers (LnPO 4 ) within the stability field of monazite (Ln = La-Gd) were synthesised within the scope of this work. To extend the knowledge of monazite phases, monoclinic TbPO 4 - and DyPO 4 -phases were prepared and characterised. Tb- and Dy-phosphates are situated in the xenotime stability field close to that of monazite. They can exist as metastable monazite phases. Structural characterisations of long- and short-range order were performed by X-ray diffraction, infrared (IR) and Raman spectroscopy. Structural data could be complemented, enhanced and gaps of knowledge could be filled by the first systematic consideration of the complete Ln-monazite-series (Ln = La-Dy). Furthermore, this work focuses on Sm-monazite phases. Samarium with an atomic number of 62 is located in the middle part of the lanthanides showing the monazite structure. Accordingly, it has a mean cationic radius within the Ln-monazite-series and hence shows a relative high flexibility regarding the incorporation of radionuclides with different radii. Sintering densities of SmPO 4 ceramics were optimised by varying process parameters like pressure and number of pressing steps. An irregular texture as well as densities of 94% of the theoretical value could be achieved. The resistance of Sm-monazite against ionising radiation were examined. Radiation damages caused by the α-decay of radionuclides incorporated in a ceramic matrix were simulated by computer calculations and experimentally by heavy ion bombardment of SmPO 4 . Thin layers of

Phosphonates as alternative to tributyl phosphate for the separation of actinides from fission products

International Nuclear Information System (INIS)

Vyas, Chirag K.; Joshirao, Pranav M.; Manchanda, Vijay K.; Rao, C.V.S. Brahmmananda; Jayalakshmi, S.

2015-01-01

The present work investigates the role of increase in the basicity of organophosphorus extractant (dialkylalkyl phosphonates) on the uptake of actinides and fission products vis-a-vis tributyl phosphate (TBP), currently employed as a universal extractant. Two dialkylalkyl phosphonates viz. dibutylpropyl phosphonate (DBPrP) and dibutylpentyl phosphonate (DBPeP) were synthesized, characterized and evaluated for their solvent extraction behavior towards U(VI), Th(IV), Eu(III) and Tc(VII) in nitric acid medium ranging from 0.01-6 M. It was observed that increasing the basicity of the phosphoryl oxygen enhanced the uptake of the actinides and the distribution coefficient values were significantly larger as compared to TBP. The limiting organic concentration (LOC) value was estimated for Th(IV) for these extractants and compared with the TBP system. The separation factors of actinides with phosphonates over Tc(VII) are distinctly better than that with TBP.

Galvanic reduction of uranium(III) chloride from LiCl-KCl eutectic salt using gadolinium metal

Science.gov (United States)

Bagri, Prashant; Zhang, Chao; Simpson, Michael F.

2017-09-01

The drawdown of actinides is an important unit operation to enable the recycling of electrorefiner salt and minimization of waste. A new method for the drawdown of actinide chlorides from LiCl-KCl molten salt has been demonstrated here. Using the galvanic interaction between the Gd/Gd(III) and U/U(III) redox reactions, it is shown that UCl3 concentration in eutectic LiCl-KCl can be reduced from 8.06 wt.% (1.39 mol %) to 0.72 wt.% (0.12 mol %) in about an hour via plating U metal onto a steel basket. This is a simple process for returning actinides to the electrorefiner and minimizing their loss to the salt waste stream.

Recent development in computational actinide chemistry

International Nuclear Information System (INIS)

Li Jun

2008-01-01

Ever since the Manhattan project in World War II, actinide chemistry has been essential for nuclear science and technology. Yet scientists still seek the ability to interpret and predict chemical and physical properties of actinide compounds and materials using first-principle theory and computational modeling. Actinide compounds are challenging to computational chemistry because of their complicated electron correlation effects and relativistic effects, including spin-orbit coupling effects. There have been significant developments in theoretical studies on actinide compounds in the past several years. The theoretical capabilities coupled with new experimental characterization techniques now offer a powerful combination for unraveling the complexities of actinide chemistry. In this talk, we will provide an overview of our own research in this field, with particular emphasis on applications of relativistic density functional and ab initio quantum chemical methods to the geometries, electronic structures, spectroscopy and excited-state properties of small actinide molecules such as CUO and UO 2 and some large actinide compounds relevant to separation and environment science. The performance of various density functional approaches and wavefunction theory-based electron correlation methods will be compared. The results of computational modeling on the vibrational, electronic, and NMR spectra of actinide compounds will be briefly discussed as well [1-4]. We will show that progress in relativistic quantum chemistry, computer hardware and computational chemistry software has enabled computational actinide chemistry to emerge as a powerful and predictive tool for research in actinide chemistry. (authors)

Actinide isotopic analysis systems

International Nuclear Information System (INIS)

Koenig, Z.M.; Ruhter, W.D.; Gunnink, R.

1990-01-01

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

Spectroscopic investigation of complexation of Cm(III) und Eu(III) with partitioning-relevant N-donor ligands

International Nuclear Information System (INIS)

Bremer, Antje

2014-01-01

The separation of trivalent actinides and lanthanides is an essential part of the development of improved nuclear fuel cycles. Liquid-liquid extraction is an applicable technique to achieve this separation. Due to the chemical similarity and the almost identical ionic radii of trivalent actinides and lanthanides this separation is, however, only feasible with highly selective extracting agents. It has been proven that molecules with soft sulphur or nitrogen donor atoms have a higher affinity for trivalent actinides. In the present work, the complexation of Cm(III) and Eu(III) with N-donor ligands relevant for partitioning has been studied by time-resolved laser fluorescence spectroscopy (TRLFS). This work aims at a better understanding of the molecular reason of the selectivity of these ligands. In this context, enormous effort has been and is still put into detailed investigations on BTP and BTBP ligands, which are the most successful N-donor ligands for the selective extraction of trivalent actinides, to date. Additionally, the complexation and extraction behavior of molecules which are structurally related to these ligands is studied. The ligand C5-BPP (2,6-bis(5-(2,2-dimethylpropyl)-1H-pyrazol-3-yl)pyridine) where the triazine rings of the aromatic backbone of the BTP ligands have been replaced by pyrazole rings is one of these molecules. Laser fluorescence spectroscopic investigation of the complexation of Cm(III) with this ligand revealed stepwise formation of three (Cm(C5-BPP) n ) 3+ complexes (n = 1 - 3). The stability constant of the 1:3 complex was determined (log β 3 = 14.8 ± 0.4). Extraction experiments have shown that, in contrast to BTP and BTBP ligands, C5-BPP needs an additional lipophilic anion source such as a 2-bromocarboxylic acid to selectively extract trivalent actinides from nitric acid solutions. The comparison of the stability constant of the (Cm(C5-BPP) 3 ) 3+ complex with the stability constant of the (Cm(nPr-BTP) 3 ) 3+ complex

Actinide recovery techniques utilizing electromechanical processes

International Nuclear Information System (INIS)

Westphal, B.R.; Benedict, R.W.

1994-01-01

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 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

Criteria for achieving actinide reduction goals

International Nuclear Information System (INIS)

Liljenzin, J.O.

1996-01-01

In order to discuss various criteria for achieving actinide reduction goals, the goals for actinide reduction must be defined themselves. In this context the term actinides is interpreted to mean plutonium and the so called ''minor actinides'' neptunium, americium and curium, but also protactinium. Some possible goals and the reasons behind these will be presented. On the basis of the suggested goals it is possible to analyze various types of devices for production of nuclear energy from uranium or thorium, such as thermal or fast reactors and accelerator driven system, with their associated fuel cycles with regard to their ability to reach the actinide reduction goals. The relation between necessary single cycle burn-up values, fuel cycle processing losses and losses to waste will be defined and discussed. Finally, an attempt is made to arrange the possible systems on order of performance with regard to their potential to reduce the actinide inventory and the actinide losses to wastes. (author). 3 refs, 3 figs, 2 tabs

Actinides: why are they important biologically

International Nuclear Information System (INIS)

Durbin, P.W.

1978-01-01

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

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

International Nuclear Information System (INIS)

Bourg, S.; Hill, C.; Ouvrier, N.

2010-01-01

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

Actinide recovery techniques utilizing electromechanical processes

International Nuclear Information System (INIS)

Westphal, B.R.; Benedict, R.W.

1994-01-01

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

Research on the chemical speciation of actinides

International Nuclear Information System (INIS)

Jung, Euo Chang; Park, K. K.; Cho, H. R.

2010-04-01

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

Actinide Separation Demonstration Facility, Tarapur

International Nuclear Information System (INIS)

Vishwaraj, I.

2017-01-01

Partitioning of minor actinide from high level waste could have a substantial impact in lowering the radio toxicity associated with high level waste as well as it will reduce the burden on geological repository. In Indian context, the partitioned minor actinide could be routed into the fast breeder reactor systems scheduled for commissioning in the near period. The technological breakthrough in solvent development has catalyzed the partitioning programme in India, leading to the setting up and hot commissioning of the Actinide Separation Demonstration Facility (ASDF) at BARC, Tarapur. The engineering scale Actinide Separation Demonstration Facility (ASDF) has been retrofitted in an available radiological hot cell situated adjacent to the Advanced Vitrification Facility (AVS). This location advantage ensures an uninterrupted supply of high-level waste and facilitates the vitrification of the high-level waste after separation of minor actinides

Interaction of Eu(III) and Cm(III) with mucin. A key component of the human mucosa

International Nuclear Information System (INIS)

Wilke, Claudia; Barkleit, Astrid

2017-01-01

To evaluate the potential health risks caused by the ingestion of lanthanides (Ln) and actinides (An), investigations into the chemical behavior of these metals in the human gastrointestinal tract are necessary. Mucin is an important part of the protective mucosa layer in the digestive system. We have recently reported that mucin interacts strongly with Eu(III) and Cm(III), representatives of Ln(III) and An(III), respectively, under in vivo conditions. In order to investigate the complexation behavior of this protein with Ln(III)/An(III), TRLFS measurements were performed on Eu(III)/Cm(III)-mucin solutions with different protein concentrations and at different pH. The results indicate the formation of at least two independent mucin species. At higher pH, the formation of hydroxide species was also observed.

Interaction of Eu(III) and Cm(III) with mucin. A key component of the human mucosa

Energy Technology Data Exchange (ETDEWEB)

Wilke, Claudia; Barkleit, Astrid [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Chemistry of the F-Elements

2017-06-01

To evaluate the potential health risks caused by the ingestion of lanthanides (Ln) and actinides (An), investigations into the chemical behavior of these metals in the human gastrointestinal tract are necessary. Mucin is an important part of the protective mucosa layer in the digestive system. We have recently reported that mucin interacts strongly with Eu(III) and Cm(III), representatives of Ln(III) and An(III), respectively, under in vivo conditions. In order to investigate the complexation behavior of this protein with Ln(III)/An(III), TRLFS measurements were performed on Eu(III)/Cm(III)-mucin solutions with different protein concentrations and at different pH. The results indicate the formation of at least two independent mucin species. At higher pH, the formation of hydroxide species was also observed.

Separation of Am(III) from Eu(III) by mixtures of triazynylbipyridine and bis(dicarbollide) extractants. The composition of the metal complexes extracted

International Nuclear Information System (INIS)

Narbutt, J.; Krejzler, J.

2006-01-01

Separation of trivalent actinides, in particular americium and curium, from lanthanides is an important step in an advanced partitioning process for future reprocessing of spent nuclear fuels. The use of soft donor (N and S) ligands makes it possible to separate the two groups of elements, probably because of the more covalent character in the complexes with actinides compared to the lanthanides. The aim of present work was to study solvent extraction of Am(III) and Eu(III) in a similar system with diethylhemi-BTP and COSAN: protonated bis(chlorodicarbollido)cobalt(III) or commo-3,3-cobalta-bis(8,9,12-trichlora-1,2-dicarbaclosododecaborane)ic acid. The present research was focused on both the determination of conditions for the separation of 241 Am(III) from 152 Eu in aqueous nitrate solution by using a synergistic extraction system and on the modelling of the process by slope analysis. Obtained values of the separation factors supported by the computer modelling permitted drawing the conclusions on the mechanism of the process and on the structure of extracted species

Partitioning of Minor Actinides from High Active Raffinates using Bis-Diglycol-amides (BisDGA) as new efficient Extractants

Energy Technology Data Exchange (ETDEWEB)

Modolo, G.; Vijgen, H. [Forschungszentrum Juelich GmbH, Institute for Energy Research, Safety Research and Reactor Technology, 52425 Juelich (Germany); Espartero, A.G. [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Avda. Complutense 22, 28040-Madrid (Spain); Prados, P. [Departamento de Quimica Organica, Facultad de Ciencias, Universidad Autonoma de Madrid - UAM, carretera de Colmenar Viejo km 15.3, 28049-Madrid (Spain); Mendoza, J. de [Departamento de Quimica Organica, Facultad de Ciencias, Universidad Autonoma de Madrid - UAM, carretera de Colmenar Viejo km 15.3, 28049-Madrid (Spain); Institut Catala d' Investigacio Quimica (ICIQ) Av. Paisos Catalans 16, 43007-Tarragona (Spain)

2008-07-01

Two new polyamide extractants has been selected, namely UAM-069 and UAM-081, both synthesized at the University of Madrid (UAM), to develop a new separation process. These two ligands are bis-diglycol-amides, consisting of two diglycol-amides moieties grafted on an aromatic platform (UAM-069) or on an aliphatic linker (UAM-081), respectively. The extraction of actinides and fission products was studied from synthetic PUREX raffinate. Actinides(III) and lanthanides(III) are highly extracted from acidities > 1 mol/L HNO{sub 3}. The extraction of Zr, Mo and Pd could be suppressed with complexing agents such as oxalic acid and HEDTA. In the present paper the results of the batch extraction results are presented which serve for the development of a new continuous counter current process to be tested in centrifugal contactors. (authors)

Actinides and environmental interfaces: striving for molecular-level understanding

International Nuclear Information System (INIS)

Heino Nitsche

2005-01-01

enhanced second harmonic generation can probe the electronic (UV-vis region) structure of metal species adsorbed at a surface or interface. Infrared-visible sum frequency generation spectroscopy probes the infrared vibrational spectrum of molecules adsorbed at the interface. SHG/SFG studies will greatly assist with understanding reactivity at interfaces of oxides and soil organic matter with heavy metals and radionuclides/actinides. Time-resolved Laser-fluorescence spectroscopy (TRLFS) is a highly sensitive tool for actinides that absorb light and de-excite by fluorescence emission, e.g., U(VI) and Cm(III), to probe changes in actinide speciation and coordination environment in solution. This method can also be used to differentiate whether adsorbed species form surface complexes or surface precipitates. Recently, it was shown that the intense synchrotron radiation can change the oxidation states of redox-sensitive actinide samples which may cause erroneous results, and low temperature measurements are now used to alleviate this shortcoming. X-ray Absorption Fine Structure (XAFS) Spectroscopy is composed of two component spectroscopies, X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) which provide element specific oxidation state and local structure information, respectively. EXAFS (Extended X-ray Absorption Fine Structure Spectroscopy) provides information on the chemical environment of particular actinide, in particular bond lengths and the number of neighboring atoms. Combining both methods, detailed knowledge of the different processes resulting from the interaction of the selected actinides with environmental interfaces can be gained. XANES and EXAFS measurements and TRLFS studies to obtain molecular-level mechanistic details of actinide interaction with common environmental solutions and interfaces will be presented together with first SHG/SFG characterization results of model systems for environmental interfaces

Synthesis and characterisation of nitrogen poly-heterocyclic molecules using as selective complexing agents of metallic cations

International Nuclear Information System (INIS)

Alphonse, F.A.

2003-12-01

Separation of actinides (III) from lanthanides (III) is a crucial problem in the reprocessing of used nuclear fuels. Experimental results shown that soft donor extractants such as nitrogen polydentate heterocycles containing a NCCNCCN coordination site are potentials ligands for selective extraction of actinides (III). In those cases, two types of liquid-liquid extractions are employed: synergistic combination with lipophilic acid extractants and direct extraction. On the basis of the Hard and Soft Acids and Bases theory and basicity evaluation, new extractants were defined. We have first studied the synthesis of potential 1,3,5-triazine ligands designed for extraction in synergy with α-bromodecanoic acid. Secondly, we have examined the synthesis of bis-triazinyl-pyridine ligands for direct extraction studies. Extraction tests were carried out and perspectives of synthesis were deducted from those extraction results. (author)

Experimental and theoretical studies on extraction of actinides and lanthanides by alicyclic H-phosphonates

Energy Technology Data Exchange (ETDEWEB)

Annam, Suresh; Sivaramakrishna, Akella; Vijayakrishna, Kari [VIT Univ., Tamil Nadu (India). Dept. of Chemistry; Gopakumar, Gopinadhanpillai; Rao, C.V.S. Brahmmananda; Sivaraman, N. [Indira Gandhi Centre for Atomic Research (IGCAR), Tamil Nadu (India). Chemistry Group

2017-06-01

Three different alicyclic substituents H-phosphonates, namely, dicyclopentyl H-phosphonate, dicyclohexyl H-phosphonate and dimenthyl H-phosphonate were synthesized and used for liquid-liquid extraction of actinide elements (U, Am and Th) and lanthanide (Gd) in n-dodecane from nitric acid medium. The physicochemical properties of the extractants, such as density, viscosity, solubility were determined. At lower acidities, these H-phosphonates exhibit higher distribution values and the extraction following cation exchange mechanism through P-OH group of tri-coordinated phosphite form. At higher acidities (2N), the extraction is primarily via solvation mechanism through P=O group of penta-coordinated phosphonate form. Amongst the three H-phosphonates, examined dimenthyl H-phosphonate showed the best results for the actinide extraction. Density functional theory (DFT) calculations were applied to understand the electronic structure of the ligands and the metal complexes. The calculated large complexation energy of UO{sub 2}(NO{sub 3}){sub 2}.@2DMnHP is in agreement with the observed trend in experimental distribution ratio data.

Subsurface Biogeochemistry of Actinides

Energy Technology Data Exchange (ETDEWEB)

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).

Comparative synergistic (technetium-actinide) extraction chemistry by tributylphosphate and some amide extractants

International Nuclear Information System (INIS)

Condamines, N.; Musikas, C.

1993-01-01

In nuclear fuel reprocessing, technetium (TcO 4 - ) leads to bad interferences in the extractions, being synergistically co-extracted with different actinide cations as Uranium (VI), Plutonium (IV) and Zirconium (IV). It destroys the hydrazine in the reductive partition of U and Pu, it decreases the decontamination of U and Pu from fission products. Thus, its extraction behaviour with new extractants as N,N-diakylamides is useful to be known. TcO 4 - extraction in nitric acid media is compared for TBP and different amides. The influence of nitric acidity is related to the amides formula

Concentration of actinides in the food chain

International Nuclear Information System (INIS)

Bulman, R.A.

1976-06-01

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)

Thermal-hydraulics of actinide burner reactors

International Nuclear Information System (INIS)

Takizuka, Takakazu; Mukaiyama, Takehiko; Takano, Hideki; Ogawa, Toru; Osakabe, Masahiro.

1989-07-01

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)

A uranium-based UO_2"+-Mn"2"+ single-chain magnet assembled trough cation-cation interactions

International Nuclear Information System (INIS)

Mougel, Victor; Chatelain, Lucile; Hermle, Johannes; Pecaut, Jacques; Mazzanti, Marinella; Caciuffo, Roberto; Colineau, Eric; Tuna, Floriana; Magnani, Nicola; Geyer, Arnaud de

2014-01-01

Single-chain magnets (SCMs) are materials composed of magnetically isolated one-dimensional (1D) units exhibiting slow relaxation of magnetization. The occurrence of SCM behavior requires the fulfillment of stringent conditions for exchange and anisotropy interactions. Herein, we report the synthesis, the structure, and the magnetic characterization of the first actinide-containing SCM. The 5f-3d heterometallic 1D chains [{[UO_2(salen)(py)][M(py)_4](NO_3)}]_n, (M=Cd (1) and M=Mn (2); py=pyridine) are assembled trough cation-cation interaction from the reaction of the uranyl(V) complex [UO_2(salen)py][Cp*_2Co] (Cp*=pentamethylcyclopentadienyl) with Cd(NO_3)_2 or Mn(NO_3)_2 in pyridine. The infinite UMn chain displays a high relaxation barrier of 134 ±0.8 K (93 ±0.5 cm"-"1), probably as a result of strong intra-chain magnetic interactions combined with the high Ising anisotropy of the uranyl(V) dioxo group. It also exhibits an open magnetic hysteresis loop at T <6 K, with an impressive coercive field of 3.4 T at 2 K. (Copyright copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Experimental findings on actinide recovery utilizing oxidation by peroxydisulfate followed by ion exchange: Fuel cycle research & development

Energy Technology Data Exchange (ETDEWEB)

Hobbs, D. T. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Shehee, T. C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2015-08-31

Our research seeks to determine if inorganic ion-exchange materials can be exploited to provide effective minor actinide (Am, Cm) separation from lanthanides. Previous work has established that a number of inorganic and UMOF ion-exchange materials exhibit varying affinities for actinides and lanthanides, which may be exploited for effective separations. During FY15, experimental work focused on investigating methods to oxidize americium in dilute nitric and perchloric acid with subsequent ion-exchange performance measurements of ion exchangers with the oxidized americium in dilute nitric acid. Ion-exchange materials tested included a variety of alkali titanates. Americium oxidation testing sought to determine the influence that other redox active components may have on the oxidation of Am^III. Experimental findings indicated that Ce^III, Np^V, and Ru^II are oxidized by peroxydisulfate, but there are no indications that the presence of Ce^III, Np^V, and Ru^II affected the rate or extent of americium oxidation at the concentrations of peroxydisulfate being used.

Determination of actinides using ICP-SFMS

International Nuclear Information System (INIS)

Nygren, Ulrika

2006-01-01

Interest in the determination of the actinides using ICP-MS has steadily increased with the development of systems capable of more sensitive and precise measurements. However, the analysis of less abundant actinides such as Pu and Am is not straightforward due to the need for chemical separation of these elements prior to determination. In many applications of mass-spectrometric actinide analysis, isotope ratio measurements are important, either for the analysis of the isotopic composition of, e.g., U or Pu in the sample, or for quantitative determinations using isotope dilution mass spectrometry. In order to achieve high precision and accuracy in an isotope ratio measurement, corrections for instrumentally induced systematic errors, e.g., due to dead-time and mass bias, need to be considered. In this thesis, different aspects of actinide analysis using ICP-SFMS have been addressed. In Papers I and III, separation procedures based on solid phase extraction for Pu, Am and U were developed and evaluated with respect to chemical yield and separation from elements causing spectral interferences. Applications of the analytical procedures developed comprised measurement of the 240 Pu/ 2 3 9Pu ratio in environmental reference materials, and age determination of Pu based on the 241 Pu/ 241 Am and 240 Pu/ 236 U ratios. In the application of different separation procedures for Pu, previously unidentified spectral interferences were discovered. In Paper II, these interferences were identified as lanthanide phosphate ions and the composition and formation of these species with respect to different instrumental parameters were further examined. Due to the importance of precise and accurate isotope ratio determination, a thorough investigation of the instrumental dead time of an ICP-SFMS system was performed. The dead time was evaluated via both isotope ratio and electronic measurements of the output from the detector amplifier. It was found that the overall uncertainty in ratio

ACSEPT-Partitioning technologies and actinide science: Towards pilot facilities in Europe

International Nuclear Information System (INIS)

Bourg, S.; Hill, C.; Caravaca, C.; Rhodes, C.; Ekberg, C.; Taylor, R.; Geist, A.; Modolo, G.; Cassayre, L.; Malmbeck, R.; Harrison, M.; Angelis, G. de; Espartero, A.; Bouvet, S.; Ouvrier, N.

2011-01-01

Highlights: → ACSEPT works at developing actinide separation processes for advanced fuel cycles. → ACSEPT develops both aqueous and pyrochemical actinide separation processes. → Homogeneous and heterogeneous recycling strategies are both considered in ACSEPT. → Training and education in actinide chemistry are important issues addressed by ACSEPT. - Abstract: Actinide recycling by separation and transmutation is considered worldwide and particularly in several European countries as one of the most promising strategies to reduce the inventory of radioactive waste and to optimise the use of natural resources. With its multidisciplinary consortium of 34 partners from 12 European countries plus Australia and Japan, the European Research Project ACSEPT (Actinide reCycling by SEParation and Transmutation) aims at contributing to the development of this strategy by studying both hydrometallurgical and pyrochemical partitioning routes. ACSEPT is organised into three technical domains: (i)Considering technically mature aqueous separation processes, ACSEPT works to optimise and select the most promising ones dedicated either to actinide partitioning (for the heterogeneous recycling of actinides in ADS target or specific actinide bearing blanket fuels in fast reactor) or to grouped actinide separation (for the homogeneous recycling of the actinides in fast reactor fuels). In addition, dissolution and conversion studies are underway taking into account the specific requirements of these specific fuels. (ii)Concerning pyrochemical separation processes, ACSEPT focuses on the enhancement of the two reference cores processes selected within FP6-EUROPART. R and D efforts are also devoted to key scientific and technical issues compulsory to set up a complete separation process (head-end steps, salt treatment for recycling and waste management). (iii)By integrating all the experimental results in engineering and system studies, both in hydro and pyro domains, ACSEPT will

Phase Behavior and Equations of State of the Actinide Oxides

Science.gov (United States)

Chidester, B.; Pardo, O. S.; Panero, W. R.; Fischer, R. A.; Thompson, E. C.; Heinz, D. L.; Prescher, C.; Prakapenka, V. B.; Campbell, A.

2017-12-01

The distribution of the long-lived heat-producing actinide elements U and Th in the deep Earth has important implications for the dynamics of the mantle and possibly the energy budget of Earth's core. The low shear velocities of the Large Low-Shear Velocity Provinces (LLSVPs) on the core-mantle boundary suggests that these regions are at least partially molten and may contain concentrated amounts of the radioactive elements, as well as other large cations such as the rare Earth elements. As such, by exploring the phase behavior of actinide-bearing minerals at extreme conditions, some insight into the mineralogy, formation, and geochemical and geodynamical effects of these regions can be gained. We have performed in situ high-pressure, high-temperature synchrotron X-ray diffraction experiments and calculations on two actinide oxide materials, UO2 and ThO2, to determine their phase behavior at the extreme conditions of the lower mantle. Experiments on ThO2 reached 60 GPa and 2500 K, and experiments on UO2 reached 95 GPa and 2500 K. We find that ThO2 exists in the fluorite-type structure to 20 GPa at high temperatures, at which point it transforms to the high-pressure cotunnite-type structure and remains thus up to 60 GPa. At room temperature, an anomalous expansion of the fluorite structure is observed prior to the transition, and may signal anion sub-lattice disorder. Similarly, UO2 exists in the fluorite-type structure at ambient conditions and up to 28 GPa at high temperatures. Above these pressures, we have observed a previously unidentified phase of UO2 with a tetragonal structure as the lower-temperature phase and the cotunnite-type phase at higher temperatures. Above 78 GPa, UO2 undergoes another transition or possible dissociation into two separate oxide phases. These phase diagrams suggest that the actinides could exist as oxides in solid solution with other analogous phases (e.g. ZrO2) in the cotunnite-type structure throughout much of Earth's lower mantle.

Actinide colloid generation in groundwater. Part 2

International Nuclear Information System (INIS)

Kim, J.I.

1991-01-01

The progress made in the investigation of actinide colloid generation in groundwater is summarized and discussed with particular examples relevant to an understanding of the migration behaviour of actinides in natural aquifer systems. The first part deals with the characterization of colloids: groundwater colloids, actinide real-colloids and actinide pseudocolloids. The second part concentrates on the generation processes and migration behaviour of actinide pseudo colloids, which are discussed with some notable experimental examples. Importance is stressed more on the chemical aspects of the actinide colloid generation in groundwater. This work is a contribution to the CEC Mirage II project, in particular the complexation and colloids research area

Creation, synthesis and characterisation of nitrogenous poly-heterocyclic new molecules for specific complexation of metallic cations; Conception, synthese et caracterisation de molecules polyheterocycliques azotees pour la complexation specifique de cations metalliques

Energy Technology Data Exchange (ETDEWEB)

Dupont, C.

2010-12-10

In France, the nuclear waste issued from the industrial reprocessing of spent nuclear fuels (by the PUREX process) are currently vitrified at the La Hague plant, waiting for a final disposal in a deep geological repository. The law voted in June 2006 on the management of highly active nuclear waste plans to look for solutions enabling the separation and transmutation of long-lived radionuclides so as to reduce the quantity and noxiousness of the final nuclear waste. To address this issue, the CEA investigates and elaborates advanced separation processes based on specially designed complexing or extracting molecules to selectively extract minor actinides from PUREX raffinates containing fission products like lanthanides, which are neutron scavengers. BTP or bis-triazinyl-pyridines have been extensively studied at the CEA (and in Europe) for actinides(III)/lanthanides(III) separation. They complex actinides(III) selectively. However, they are sensitive to degradation by hydrolysis and radiolysis. Besides, their separation mechanisms are not well understood, especially the influence of their substituting groups on their complexing and extracting properties. The first part of work reports the syntheses of various BTP and BTBP molecules, differently substituted, as well as a new family of poly-aromatic nitrogen-contained ligands: BPBT, presenting a pyridine/triazine sequence that has never been reported in the literature. The second part is devoted to the physico-chemistry studies of the synthesized molecules, such as the determination of their protonation and complexation constants to describe the influence of different substituting groups. Finally, the last part outlines solvent extraction studies by using these ligands either like extractants or like complexants. (author) [French] Resume: La loi du 6 juin 2006 sur la gestion des dechets radioactifs de haute activite et a vie longue prevoit la recherche de solutions permettant la separation et la transmutation des

Strategic Design and Optimization of Inorganic Sorbents for Cesium, Strontium and Actinides

International Nuclear Information System (INIS)

Maginn, Edward J.

2009-01-01

The primary objective of the Notre Dame component of the project was computational in nature. The goal was to provide a design tool for the synthesis of optimized sorbents for the removal of cesium, strontium and actinides from nuclear waste solutions. Molecular modeling enables us to observe and better understand the molecular level interactions that govern the selectivity of specific radionuclides in a particular sorbent. The research focused on the development and validation of a suitable and transferable model for all the cations and ion exchangers of interest, nd then subsequent simulations which determined the siting and mobility of water and cations. Speciic accomplishments include: (1) improving existing intermolecular force fields to accurately model the sorbents of interest; (2) utilizing energy-minimizations and molecular dynamics simulations for structural prediction of CST and niobium-substituted CST materials; (3) determining Na+/water positions in polyoxoniobate materials using molecular dynamics simulations; and (4) developing Hybrid Monte Carlo methods for improved structural prediction.

Extraction chromatogrpahy of actinides, ch. 7

International Nuclear Information System (INIS)

Mueller, W.

1975-01-01

This review on extraction chromatography of actinides emphasizes the important usage of neutral (Tributylphosphate), basic (substituted ammonium salts), and acidic (HDEHP) extractants, and their application to separations of actinides in the di-to hexavalent oxidation state. Furthermore, the actinide extraction by ketones, ethers, alcohols and β-diketones is discussed

Position of actinide elements in the periodic table : evolution of a generalised form (Preprint no. SSC-33)

International Nuclear Information System (INIS)

Nathaniel, T.N.

1991-01-01

All the actinides and lanthanides are placed in III group and are shown separately, in the most popular forms of the periodic table, including the latest version of IUPAC. This has been leading to an avoidable debate i.e. whether to place La and Ac or Lu and Lw below Sc and Y in the III-B group. Apart from this, the group characteristic nature of most of the actinides elements, demands that a more appropriate position is to be given to these f block elements. The situation is more complex in the higher periods, in which new elements belonging to g block, h block, ... are to be included. Also, there seems to be no consensus in following a uniform and acceptable subgroup notation. The author arrived at a new form of the periodic table to successfully sort out all these issues. The table is presented. (author). 10 refs., 1 fig

Minor actinide transmutation on PWR burnable poison rods

International Nuclear Information System (INIS)

Hu, Wenchao; Liu, Bin; Ouyang, Xiaoping; Tu, Jing; Liu, Fang; Huang, Liming; Fu, Juan; Meng, Haiyan

2015-01-01

Highlights: • Key issues associated with MA transmutation are the appropriate loading pattern. • Commercial PWRs are the only choice to transmute MAs in large scale currently. • Considerable amount of MA can be loaded to PWR without disturbing k eff markedly. • Loading MA to PWR burnable poison rods for transmutation is an optimal loading pattern. - Abstract: Minor actinides are the primary contributors to long term radiotoxicity in spent fuel. The majority of commercial reactors in operation in the world are PWRs, so to study the minor actinide transmutation characteristics in the PWRs and ultimately realize the successful minor actinide transmutation in PWRs are crucial problem in the area of the nuclear waste disposal. The key issues associated with the minor actinide transmutation are the appropriate loading patterns when introducing minor actinides to the PWR core. We study two different minor actinide transmutation materials loading patterns on the PWR burnable poison rods, one is to coat a thin layer of minor actinide in the water gap between the zircaloy cladding and the stainless steel which is filled with water, another one is that minor actinides substitute for burnable poison directly within burnable poison rods. Simulation calculation indicates that the two loading patterns can load approximately equivalent to 5–6 PWR annual minor actinide yields without disturbing the PWR k eff markedly. The PWR k eff can return criticality again by slightly reducing the boric acid concentration in the coolant of PWR or removing some burnable poison rods without coating the minor actinide transmutation materials from PWR core. In other words, loading minor actinide transmutation material to PWR does not consume extra neutron, minor actinide just consumes the neutrons which absorbed by the removed control poisons. Both minor actinide loading patterns are technically feasible; most importantly do not need to modify the configuration of the PWR core and

Effect of alkali cations on two-dimensional networks of two new quaternary thioarsenates (III) prepared by a facile surfactant-thermal method

Energy Technology Data Exchange (ETDEWEB)

Yan, Dongming [School of Civil and Architectural Engineering, Zhejiang University, Hangzhou 310058 (China); Hou, Peipei; Liu, Chang [State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Chai, Wenxiang [College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Zheng, Xuerong [State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Zhang, Luodong [School of Civil and Architectural Engineering, Zhejiang University, Hangzhou 310058 (China); Zhi, Mingjia; Zhou, Chunmei [State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Liu, Yi, E-mail: liuyimse@zju.edu.cn [State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

2016-09-15

Two new quaternary thioarsenates(III) NaAg{sub 2}AsS{sub 3}·H{sub 2}O (1) and KAg{sub 2}AsS{sub 3} (2) with high yields have been successfully prepared through a facile surfactant-thermal method. It is interesting that 2 can only be obtained with the aid of ethanediamine (en), which indicates that weak basicity of solvent is beneficial to the growth of 2 compared with 1. Both 1 and 2 feature the similar two-dimensional (2D) layer structures. However, the distortion of the primary honeycomb-like nets in 2 is more severe than that of 1, which demonstrates that Na{sup +} and K{sup +} cations have different structure directing effects on these two thioarsenates(III). Both experimental and theoretical studies confirm 1 and 2 are semiconductors with band gaps in the visible region. Our success in preparing these two quaternary thioarsenates(III) proves that surfactant-thermal technique is a powerful yet facile synthetic method to explore new complex chalcogenides. - Graphical abstract: Two new quaternary thioarsenates(III) NaAg{sub 2}AsS{sub 3}·H{sub 2}O (1) and KAg{sub 2}AsS{sub 3} (2) with high yields have been successfully prepared through a facile surfactant-thermal method. X-ray single crystal diffraction analyses demonstrate that Na{sup +} and K{sup +} cations have different structure directing effects on these two thioarsenates(III). Both experimental and theoretical studies confirm 1 and 2 are semiconductors with band gaps in the visible region. Display Omitted - Highlights: • NaAg{sub 2}AsS{sub 3}⋅H{sub 2}O (1) and KAg{sub 2}AsS{sub 3} (2) were prepared through surfactant-thermal method. • Crystal structures show Na{sup ±} and K{sup ±} have different structure directing effects. • The weak basicity of solvent is benefit to the growth of 2 compared with 1. • Experimental and theoretical studies confirm 1 and 2 are semiconductors.

Research on the chemical speciation of actinides

International Nuclear Information System (INIS)

Jung, Euo Chang; Park, K. K.; Cho, H. R.

2012-04-01

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

Safe actinide disposition in molten salt reactors

International Nuclear Information System (INIS)

Gat, U.

1997-01-01

Safe molten salt reactors (MSR) can readily accommodate the burning of all fissile actinides. Only minor compromises associated with plutonium are required. The MSRs can dispose safely of actinides and long lived isotopes to result in safer and simpler waste. Disposing of actinides in MSRs does increase the source term of a safety optimized MSR. It is concluded that the burning and transmutation of actinides in MSRs can be done in a safe manner. Development is needed for the processing to handle and separate the actinides. Calculations are needed to establish the neutron economy and the fuel management. 9 refs

The role of humic acid on the formation of HAS (hydroxy-aluminosilicate) colloid-borne actinides

Energy Technology Data Exchange (ETDEWEB)

Priemyshev, A.; Kim, M.A. [Inst. fuer Radiochemie, Technische Universitaet Muenchen, D-85748 Garching (Germany); Breban, D.; Panak, P.J.; Yun, J.I.; Kim, J.I.; Fanghanel, Th. [Inst. fuer Nukleare Entsorgung, Forschungszentrum Karlsruhe, D-76021 Karlsruhe (Germany); Mansel, A. [Inst. fuer Interdisziplinaere Isotopenforschung, Georadiochemie, Leipzig, D-04318 Leipzig (Germany)

2005-07-01

Full text of publication follows: One of the major unknowns in the process of actinide migration is the formation of their colloid-borne species. Previous studies have been directed to the incorporation of actinides into HAS (hydroxy-aluminosilicate) colloids generated by the nucleation of Si and Al. The present work further pursues the behaviour of actinides at HAS colloid formation but in the presence of humic acid that is known to be an ubiquitous groundwater constituent. The formation and degree of stability of the aluminosilicate binding for the generation of HAS colloids are investigated at first in the absence of actinides. Free and complexed Al resulting from ligand competitions reactions for the complexation of Al with mono-silicic acid, poly-silicic acid and EDTA are monitored spectroscopically by colour reaction. The second part of the study concentrates on the formation and stability of humic colloids using {sup 14}C-labeled humic acid. The activity distribution is ascertained in the ionic, colloidal and precipitated fractions under different conditions of colloid formation, e.g. as a function of pH, time, humic acid and Al concentration. The third part follows the appraisal of appropriate conditions under which stable HAS and humic colloids are formed, and their interaction with actinides, either separately or in competition. Trace actinides of different oxidation states {sup 241}Am(III), {sup 234}Th(IV) and {sup 233}U(VI) are taken for the purpose. HAS colloids generated from poly-silicic acid at neutral pH show EDTA-resistance, whereas HAS colloids formed from mono-silicic acid become EDTA-resistant only by aging (> one month). Humic acid appears to stabilize HAS colloids, unless the loading capacity of humic acid for the Al ion is exceeded. The incorporation of actinides into the colloidal phase is generally enhanced in the presence of humic acid. Synergic effects produce chimeric HAS-humic colloids into which tri-, tetra- and hexavalent actinides

Crystal structure of octakis(4-methoxypyridinium bis(4-methoxypyridine-κNtetrakis(thiocyanato-κNferrate(III bis[(4-methoxypyridine-κNpentakis(thiocyanato-κNferrate(III] hexakis(thiocyanato-κNferrate(III with iron in three different octahedral coordination environments

Directory of Open Access Journals (Sweden)

Aleksej Jochim

2018-03-01

Full Text Available The crystal structure of the title salt, (C6H8NO8[Fe(NCS4(C6H7NO2][Fe(NCS5(C6H7NO]2[Fe(NCS6], comprises three negatively charged octahedral FeIII complexes with different coordination environments in which the FeIII atoms are coordinated by a different number of thiocyanate anions and 4-methoxypyridine ligands. Charge balance is achieved by 4-methoxypyridinium cations. The asymmetric unit consists of three FeIII cations, one of which is located on a centre of inversion, one on a twofold rotation axis and one in a general position, and ten thiocyanate anions, two 4-methoxypyridine ligands and 4-methoxypyridinium cations (one of which is disordered over two sets of sites. Beside to Coulombic interactions between organic cations and the ferrate(III anions, weak N—H...S hydrogen-bonding interactions involving the pyridinium N—H groups of the cations and the thiocyanate S atoms of the complex anions are mainly responsible for the cohesion of the crystal structure.

Application of multi-step excitation schemes for detection of actinides and lanthanides in solutions by luminescence/chemiluminescence laser spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Izosimov, I. [Joint Institute for Nuclear Research, Joliot Curie 6, Dubna 141980 (Russian Federation)

2016-07-01

The use of laser radiation with tunable wavelength allows the selective excitation of actinide/lanthanide species with subsequent registration of luminescence/chemiluminescence for their detection. This work is devoted to applications of the time-resolved laser-induced luminescence spectroscopy and time-resolved laser-induced chemiluminescence spectroscopy for the detection of lanthanides and actinides. Results of the experiments on U, Eu, and Sm detection by TRLIF (Time Resolved Laser Induced Fluorescence) method in blood plasma and urine are presented. Data on luminol chemiluminescence in solutions containing Sm(III), U(IV), and Pu(IV) are analyzed. It is shown that appropriate selectivity of lanthanide/actinide detection can be reached when chemiluminescence is initiated by transitions within 4f- or 5f-electron shell of lanthanide/actinide ions corresponding to the visible spectral range. In this case chemiluminescence of chemiluminogen (luminol) arises when the ion of f element is excited by multi-quantum absorption of visible light. The multi-photon scheme of chemiluminescence excitation makes chemiluminescence not only a highly sensitive but also a highly selective tool for the detection of lanthanide/actinide species in solutions. (author)

QSAR studies of multidentate nitrogen ligands used in lanthanide and actinide extraction processes

International Nuclear Information System (INIS)

Drew, Michael G.B.; Hudson, Michael J.; Youngs, Tristan G.A.

2004-01-01

Quantitative structure activity relationships (QSARs) have been developed to optimise the choice of nitrogen heterocyclic molecules that can be used to separate the minor actinides such as americium(III) from europium(III) in the aqueous PUREX raffinate of nuclear waste. Experimental data on distribution coefficients and separation factors (SFs) for 47 such ligands have been obtained and show SF values ranging from 0.61 to 100. The ligands were divided into a training set of 36 molecules to develop the QSAR and a test set of 11 molecules to validate the QSAR. Over 1500 molecular descriptors were calculated for each heterocycle and the Genetic Algorithm was used to select the most appropriate for use in multiple regression equations. Equations were developed fitting the separation factors to 6-8 molecular descriptors which gave r 2 values of >0.8 for the training set and values of >0.7 for the test set, thus showing good predictive quality. The descriptors used in the equations were primarily electronic and steric. These equations can be used to predict the separation factors of nitrogen heterocycles not yet synthesised and/or tested and hence obtain the most efficient ligands for lanthanide and actinide separation

Liquid-liquid extraction of actinides by means of dibutil-N, N-diethylcarbamylphosphanate (DBDECP)

International Nuclear Information System (INIS)

Spezzano, P.; Giacomelli, R.; Sarzanini, C.; Volpe, P.; Benzi, P.

1988-01-01

The extraction of Th(IV), U(VI), Pu(IV), Am(III) and Cm(III) by dibutyl-N, N-diethilcarbamoylphosphonate (DBDECP) from notric, hydrochloric and perchloric acid solutions has been studies as a function of a number of parameters. The effect of size and structure of the extractant molecules has been investigated for lower homologues of carbamoyphosphonate. After evaluating the effect of the diluent, the extraction of inorganic acid HNO 3 , HCl and HClO 4 and the dipendence of the distribution ratios of the actinides from organic extractant concentration and aqueous acid concentration has been studied for the DBDECP-xilene system

Mechanistic role of citric acid in the sorption of Eu(III) at titania - water interface

International Nuclear Information System (INIS)

Kumar, Sumit; Kasar, Sharayu; Tomar, B.S.

2014-01-01

In view of the deep underground disposal strategy of nuclear high level waste, environmental behavior of long lived radionuclides, such as, trivalent actinides Am(III) and Cm(III), attract significant scientific attention. Interaction of trivalent actinides with anatase (TiO 2 ) in presence of citric acid has been investigated in the present work using Eu(III) batch sorption studies and the role of citric acid in influencing sorption of Eu(III) on anatase was delineated using surface speciation of Eu(III) and citric acid on anatase surface. Results from ATR-FTIR spectroscopic study have been invoked to determine the binding of citric acid on anatase surface. Eu(III) sorption on anatase increases sharply to quantitative value over pH 3- 6 and remains at 100% upto pH 10. In presence of citric acid, there is no change in Eu(III) sorption in the pH range 2-5 whereas significant lowering in Eu(III) sorption percentage was obtained in the pH range 5-8. Above pH 8 the sorption percentage reached quantitative value

Actinides burnup in a sodium fast reactor

Energy Technology Data Exchange (ETDEWEB)

Ramirez S, J. R.; Pineda A, R.; Martinez C, E.; Alonso, G., E-mail: ramon.ramirez@inin.gob.mx [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

2017-09-15

The burnup of actinides in a nuclear reactor is been proposed as part of an advanced nuclear fuel cycle, this process would close the fuel cycle recycling some of the radioactive material produced in the open nuclear fuel cycle. These actinides are found in the spent nuclear fuel from nuclear power reactors at the end of their burnup in the reactor. Previous studies of actinides recycling in thermal reactors show that would be possible reduce the amounts of actinides at least in 50% of the recycled amounts. in this work, the amounts of actinides that can be burned in a fast reactor is calculated, very interesting results surge from the calculations, first, the amounts of actinides generated by the fuel is higher than for thermal fuel and the composition of the actinides vector is different as in fuel for thermal reactor the main isotope is the {sup 237}Np in the fuel for fast reactor the main isotope is the {sup 241}Am, finally it is concluded that the fast reactor, also generates important amounts of waste. (Author)

Burning actinides in very hard spectrum reactors

International Nuclear Information System (INIS)

Robinson, A.H.; Shirley, G.W.; Prichard, A.W.; Trapp, T.J.

1978-01-01

The major unresolved problem in the nuclear industry is the ultimate disposition of the waste products of light water reactors. The study demonstrates the feasibility of designing a very hard spectrum actinide burner reactor (ABR). A 1100 MW/sub t/ ABR design fueled entirely with actinides reprocessed from light water reactor (LWR) wastes is proposed as both an ultimate disposal mechanism for actinides and a means of concurrently producing usable power. Actinides from discharged ABR fuel are recycled to the ABR while fission products are routed to a permanent repository. As an integral part of a large energy park, each such ABR would dispose of the waste actinides from 2 LWRs

Actinide separative chemistry

International Nuclear Information System (INIS)

Boullis, B.

2004-01-01

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

Actinides integral measurements on FCA assemblies

International Nuclear Information System (INIS)

Mukaiyama, Takehiko; Okajima, Shigeaki

1984-01-01

Actinide integral measurements were performed on eight assemblies of FCA where neutron energy spectra were shifted systematically from soft to hard in order to evaluate and modify the nuclear cross section data of major actinides. Experimental values on actinide fission rates and sample reactivity worths are compared with the calculated values using JENDL-2 and ENDF/B-V (or IV) data sets. (author)

Specific sequestering agents for iron and the actinides

Energy Technology Data Exchange (ETDEWEB)

Raymond, K.N.

1983-06-01

The transuranium actinide ions represent one unique environmental hazard associated with the waste of the nuclear power industry. A major component associated with that waste and a potential hazard is plutonium. The synthesis of metal-ion-specific complexing agents for ions such as Pu(IV) potentially represents a powerful new approach to many of the problems posed by waste treatment. This document is a progress report of a rational approach to the synthesis of such chelating agents based on the similarities of Pu(IV) and Fe(III), the structures of naturally-occurring complexing agents which are highly specific for Fe(III), and the incorporation of the same kinds of ligating groups present in the iron complexes to make octadentate complexes highly specific for plutonium. Both thermodynamic and animal test results indicate that a relatively high degree of success has already been achieved in this aim.

Theoretical study of the structure and the reactivity of lanthanides and actinides complexes: Activation of small molecules

International Nuclear Information System (INIS)

Castro, Ludovic

2012-01-01

This PhD thesis presents a theoretical study of the structure and the reactivity of organometallic complexes of lanthanides and actinides at the DFT level. After a general introduction of the methods of theoretical chemistry used for the modelling of organometallic reactivity, a study of the participation of 5f electrons in uranium(IV) reactivity is presented. The results show that the large core ECP can be used safely in order to treat the actinide and so that 5f electrons can be treated implicitly. Then, the reactivity of uranium(III) complexes with CO 2 and other analogous molecules is studied via multiple examples from the literature. These studies show that the steric nature of the ligands is very important and controls the reactivity. This study is then extended to samarium(II) complex. Eventually, the reactivity of a hydride complex of cerium(III) with MeOSO 2 Me is investigated and theoretical results are compared with experimental observations. (author) [fr

Actinide burning and waste disposal

Energy Technology Data Exchange (ETDEWEB)

Pigford, T H [University of California, Berkeley, CA (United States)

1990-07-01

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

Actinide burning and waste disposal

International Nuclear Information System (INIS)

Pigford, T.H.

1990-01-01

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

Aqueous complexes of lanthanides(III) and actinides(III) with the carbonate and sulphate ions. Thermodynamic study by time-resolved laser-induced fluorescence spectroscopy and electro-spray-ionisation mass spectrometry

International Nuclear Information System (INIS)

Vercouter, Th.

2005-03-01

The prediction of the environmental impact of a possible geological disposal of radioactive wastes is supported by the thermodynamic modelling of the radionuclides behaviour in the groundwater. In this framework, the analogy between lanthanides and actinides(III) is confirmed by a critical analysis of the literature and the comparison with experimental results obtained here. The limiting complex, Eu(CO 3 ) 3 3- , is identified by solubility measurements in Na 2 CO 3 solutions. Then the formation constants of the complexes Eu(CO 3 ) i 3-2i (i=1-3) and Eu(SO 4 ) i 3-2i (i=1-2) are measured by TRLFS. The formation of aqueous LaSO 4 + is studied by ESI-MS and is in good agreement with the expected speciation. The enthalpy and entropy of the reaction Cm(CO 3 ) 2 - + CO 3 2- ↔ Cm(CO 3 ) 3 3- are deduced from TRLFS measurements of the equilibrium constant between 10 and 70 C. The ionic strength effect is calculated using the SIT formula. (author)

Chemistry of actinides and fission products

International Nuclear Information System (INIS)

Pruett, D.J.; Sherrow, S.A.; Toth, L.M.

1988-01-01

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

An independent method for data selection of long-life radionuclides (actinides and fission products) in the geosphere

International Nuclear Information System (INIS)

Henry, M.; Merceron, T.

1994-01-01

An independent method for data selection of long-life radio-nuclides based on the electronegativity equalization principle is proposed to predict the speciation of metal cations as a function of the solution pH. Hydrolysis, condensation and complexation reactions of metal cations in aqueous media are, by this simple model, unified and can be analyzed in terms of electronegativities, oxidation states and coordination numbers with a specific PC software. This paper describes the thermodynamical basis and the underlying concepts of the model in relation to aqueous actinide chemistry of elements such as U and Tc. It is then shown that the model could provide a complementary approach to existing softwares based on thermodynamic data bases allowing to make intelligent and reasonnable choices for the various complexes to consider in complex geochemical codes. (orig.)

Catalytic Organic Transformations Mediated by Actinide Complexes

Directory of Open Access Journals (Sweden)

Isabell S. R. Karmel

2015-10-01

Full Text Available This review article presents the development of organoactinides and actinide coordination complexes as catalysts for homogeneous organic transformations. This chapter introduces the basic principles of actinide catalysis and deals with the historic development of actinide complexes in catalytic processes. The application of organoactinides in homogeneous catalysis is exemplified in the hydroelementation reactions, such as the hydroamination, hydrosilylation, hydroalkoxylation and hydrothiolation of alkynes. Additionally, the use of actinide coordination complexes for the catalytic polymerization of α-olefins and the ring opening polymerization of cyclic esters is presented. The last part of this review article highlights novel catalytic transformations mediated by actinide compounds and gives an outlook to the further potential of this field.

Burn of actinides in MOX fuel cells

International Nuclear Information System (INIS)

Martinez C, E.; Ramirez S, J. R.; Alonso V, G.

2017-09-01

The spent fuel from nuclear reactors is stored temporarily in dry repositories in many countries of the world. However, the main problem of spent fuel, which is its high radio-toxicity in the long term, is not solved. A new strategy is required to close the nuclear fuel cycle and for the sustain ability of nuclear power generation, this strategy could be the recycling of plutonium to obtain more energy and recycle the actinides generated during the irradiation of the fuel to transmute them in less radioactive radionuclides. In this work we evaluate the quantities of actinides generated in different fuels and the quantities of actinides that are generated after their recycling in a thermal reactor. First, we make a reference calculation with a regular enriched uranium fuel, and then is changed to a MOX fuel, varying the plutonium concentrations and determining the quantities of actinides generated. Finally, different amounts of actinides are introduced into a new fuel and the amount of actinides generated at the end of the fuel burn is calculated, in order to determine the reduction of minor actinides obtained. The results show that if the concentration of plutonium in the fuel is high, then the production of minor actinides is also high. The calculations were made using the cell code CASMO-4 and the results obtained are shown in section 6 of this work. (Author)

Solubility Determination of Uranium (IV) Oxalates U(C2O4)2.6H2O and M2U2(C2O4)5.nH2O (M = mono-charged cation)

International Nuclear Information System (INIS)

Costenoble, Sylvain; Grandjean, Stephane; Arab-Chapelet, Benedicte; Abraham, Francis

2008-01-01

The solubility of uranium (IV) oxalate compounds was studied in order to have a precise insight of the behaviour of An(IV)-An(III) (An(IV) = U, Np or Pu and An(III) = Pu or Am) mixed oxalate in the context of oxalic co-conversion for actinide co-management. Concepts of thermodynamics of aqueous-solid solution are reviewed by introducing LIPPMANN theory and THORSTENSON and PLUMMER 'stoichiometric saturation' model in a way to understand and model the system of interest. Different analytical techniques have been developed in order to titrate uranium and/or other actinides at trace levels in solution. This thorough investigation is the basis of further experiments on the solubility of mixed U(IV)- An(III) oxalate solid solutions as a function of the nature of the trivalent actinide and the An(III)/U(IV) ratio. (authors)

Minor actinide transmutation - a waste management option

International Nuclear Information System (INIS)

Koch, L.

1986-01-01

The incentive to recycle minor actinides results from the reduction of the long-term α-radiological risk rather than from a better utilization of the uranium resources. Nevertheless, the gain in generated electricity by minor actinide transmutation in a fast breeder reactor can compensate for the costs of their recovery and make-up into fuel elements. Different recycling options of minor actinides are discussed: transmutation in liquid metal fast breeder reactors (LMFBRs) is possible as long as plutonium is not recycled in light water reactors (LWRs). In this case a minor actinide burner with fuel of different composition has to be introduced. The development of appropriate minor actinide fuels and their properties are described. The irradiation experiments underway or planned are summarized. A review of minor actinide partitioning from the PUREX waste stream is given. From the present constraints of LMFBR technology a reduction of the long-term α-radiological risk by a factor of 200 is deduced relative to that from the direct storage of spent LWR fuel. Though the present accumulation of minor actinides is low, nuclear transmutation may be needed when nuclear energy production has grown. (orig.)

The development of a laser-induced photoacoustic facility for actinide speciation

International Nuclear Information System (INIS)

Ewart, F.T.; McMillan, J.W.; Pollard, P.M.; Thomason, H.P.; Liezers, M.

1987-09-01

A laser induced photoacoustic spectroscopy (LIPAS) facility has been developed at Harwell to measure actinide species in solution with the minimal disturbance of the species equilibria. The novel true dual beam system, which is based on an excimer laser driven dye laser and optical cells mounted on piezoelectric detectors, has high sensitivity and stability, and is capable of detecting Am(III) at ca 10 -8 M and Np(IV), (V) and (VI) at ca 10 -7 M. Samples can be measured in an inert atmosphere glove box which helps to maintain the anaerobic conditions expected in deep waste repositories. To date, LIPAS has been used to measure actinide species directly in solutions from waste programmes and to observe americium and neptunium species in solutions of varying Eh, pH and carbonate concentration. The information gained is being used to validate the data used in the geochemical/thermodynamic codes used to predict possible radionuclide species within a radioactive waste repository. (author)

The development of a laser-induced photoacoustic facility for actinide speciation

International Nuclear Information System (INIS)

Ewart, F.T.; McMillan, J.W.; Thomason, H.P.; Liezers, M.; Pollard, P.M.

1988-02-01

A laser induced photoacoustic spectroscopy (LIPAS) facility has been developed at Harwell to measure actinide species in solution with the minimal disturbance of the species equilibria. The novel true dual beam system, which is based on an excimer laser driven dye laser and optical cells mounted on piezoelectric detectors, has high sensitivity and stability, and is capable of detecting Am(III) at ca 10 -8 M and Np(IV), (V) and (VI) at ca 10 -7 M. Samples can be measured in an inert atmosphere glove box which helps to maintain the anaerobic conditions expected in deep waste repositories. To date, LIPAS has been used to measure actinide species directly in solutions from waste programmes and to observe americium and neptunium species in solutions of varying Eh, pH and carbonate concentration. The information gained is being used to validate the data used in the geochemical/thermodynamic codes used to predict possible radionuclide species within a radioactive waste repository. (author)

Ammonium diphosphitoindate(III

Directory of Open Access Journals (Sweden)

Farida Hamchaoui

2013-04-01

Full Text Available The crystal structure of the title compound, NH4[In(HPO32], is built up from InIII cations (site symmetry 3m. adopting an octahedral environment and two different phosphite anions (each with site symmetry 3m. exhibiting a triangular–pyramidal geometry. Each InO6 octahedron shares its six apices with hydrogen phosphite groups. Reciprocally, each HPO3 group shares all its O atoms with three different metal cations, leading to [In(HPO32]− layers which propagate in the ab plane. The ammonium cation likewise has site symmetry 3m.. In the structure, the cations are located between the [In(HPO32]− layers of the host framework. The sheets are held together by hydrogen bonds formed between the NH4+ cations and the O atoms of the framework.

Cobalt bis(dicarbollide) ions with covalently bonded CMPO groups as selective extraction agents for lanthanide and actinide cations from highly acidic nuclear waste solutions

International Nuclear Information System (INIS)

Gruner, B.; Plesek, J.; Baca, J.; Cisarova, I.; Dozol, J.F.; Rouquette, H.; Vinas, C.; Selucky, P.; Rais, J.

2002-01-01

A new series of boron substituted cobalt bis(dicarbollide)(1-) ion (1) derivatives of the general formula [(8-CMPO-(CH 2 -CH 2 O) 2 -1,2-C 2 B 9 H 10 )(1',2'-C 2 B 9 H 11 )-3,3'-Co] - (CMPO = Ph 2 P(O)-CH 2 C(O)NR, R = C 4 H 9 (3b), -C 12 H 25 (4b), -CH 2 -C 6 H 5 (5b)) was prepared by ring cleavage of the 8-dioxane-cobalt bis(dicarbollide) (2) bi-polar compound by the respective primary amines and by subsequent reaction of the resulting amino derivatives (3a-5a) with the nitrophenyl ester of diphenyl-phosphoryl-acetic acid. The compounds were synthesized with the aim to develop a new class of more efficient extraction agents for liquid/liquid extraction of polyvalent cations, i.e. lanthanides and actinides, from high-level activity nuclear waste. All compounds were characterized by a combination of 11 B NMR, 1 H high field NMR, Mass Spectrometry with Electro-spray and MALDI TOF ionisation, HPLC and other techniques. The molecular structure of the supramolecular Ln 3+ complex of the anion 5b was determined by single crystal X-ray diffraction analysis. Crystallographic results proved that the Ln(m) atom is bonded to three functionalized cobalt bis(dicarbollide) anions in a charge compensated complex. The cation is tightly coordinated by six oxygen atoms of the CMPO terminal groups (two of each ligand) and by three water molecules completing the metal coordination number to 9. Atoms occupying the primary coordination sphere form a tri-capped trigonal prismatic arrangement. Very high liquid-liquid extraction efficiency of all anionic species was observed. Moreover, less polar toluene can be applied as an auxiliary solvent replacing the less environmentally friendly nitro- and chlorinated solvents used in the current dicarbollide liquid-liquid extraction process. The extraction coefficients are sufficiently high for possible technological applications. (authors)

A uranium-based UO{sub 2}{sup +}-Mn{sup 2+} single-chain magnet assembled trough cation-cation interactions

Energy Technology Data Exchange (ETDEWEB)

Mougel, Victor; Chatelain, Lucile; Hermle, Johannes; Pecaut, Jacques; Mazzanti, Marinella [CEA-Grenoble (France). Lab. de Reconnaissance Ionique et Chimie de Coordination; Caciuffo, Roberto; Colineau, Eric [European Commission, Karlsruhe (Germany). Inst. for Transuranium Elements; Tuna, Floriana [Manchester Univ. (United Kingdom). School of Chemistry; Magnani, Nicola [KIT Karlsruhe (Germany). Inst. of Nanotechnology; Geyer, Arnaud de [CEA-Grenoble (France). Service General des Rayons X

2014-01-13

Single-chain magnets (SCMs) are materials composed of magnetically isolated one-dimensional (1D) units exhibiting slow relaxation of magnetization. The occurrence of SCM behavior requires the fulfillment of stringent conditions for exchange and anisotropy interactions. Herein, we report the synthesis, the structure, and the magnetic characterization of the first actinide-containing SCM. The 5f-3d heterometallic 1D chains [{[UO_2(salen)(py)][M(py)_4](NO_3)}]{sub n}, (M=Cd (1) and M=Mn (2); py=pyridine) are assembled trough cation-cation interaction from the reaction of the uranyl(V) complex [UO{sub 2}(salen)py][Cp{sup *}{sub 2}Co] (Cp{sup *}=pentamethylcyclopentadienyl) with Cd(NO{sub 3}){sub 2} or Mn(NO{sub 3}){sub 2} in pyridine. The infinite UMn chain displays a high relaxation barrier of 134±0.8 K (93±0.5 cm{sup -1}), probably as a result of strong intra-chain magnetic interactions combined with the high Ising anisotropy of the uranyl(V) dioxo group. It also exhibits an open magnetic hysteresis loop at T<6 K, with an impressive coercive field of 3.4 T at 2 K.

Plutonium Management, Minor Actinides Partitioning and Transmutation R and D in France

International Nuclear Information System (INIS)

Cavedon, Jean-Marc; Courtois, Charles

2003-01-01

Jean-Marc Cavedon (CEA, France) then presented the developments concerning Plutonium management and minor actinides P and T research and development in France. By the 1991 law on high-level long-lived radioactive waste a research programme was launched in the areas: (i) geological disposal, (ii) conditioning and long-term storage, and (iii) radiotoxicity reduction by P and T. The results of the work in these areas will be presented to the French Government and Parliament in 2006. The control of Plutonium stocks generated by the French PWRs is proposed to increase Plutonium consumption in reactors and minimise radioactive waste production, and requires the recycling of actinides, especially Plutonium. In the long term, CEA intends to develop a new technology based on gas cooled reactors and their associated fuel cycle, including multiple recycling of Plutonium. The advantages of this development consist in the optimisation of the use of natural resources and the concentration of Plutonium in limited quantities of fuel rods. If needed, the minor actinides could also be recycled. The planned CEA developments depend on new fuel types and will lead to novel waste types (light glasses) with a reduction of long-term radiotoxicity. Radiotoxicity reductions by a factor of 3 to 5 are expected for Plutonium recycling scenarios, and by up to a factor of a few hundreds for Plutonium and minor actinides recycling scenarios. This gain is nearly independent on the reactor type used, but needs about 100 years of application to become effective in terms of making a difference in the total waste inventory to be disposed of

Moessbauer effect studies with actinides

International Nuclear Information System (INIS)

Stone, J.A.

1966-01-01

Moessbauer resonance studies in the actinide elements offer a new technique for measuring solid-state properties to a region of the periodic chart where such information is relatively sparse. It is well known that the actinides, the elements with atomic numbers from 90 to 103, form a transition series due to filling of the 5f electron shell, analogous to the rare-earth series in which the 4f shell is filled. Like the rare earths, the actinide metals and compounds are expected to exhibit a variety of interesting magnetic properties, but, unlike the rare earths, there have been few studies of the magnetic behaviour of actinides, and these properties are largely unknown. The chemical properties of the actinides have been studied somewhat more extensively, and, in contrast to the rare earths, form a multiplicity of stable valence states, especially in the lighter members of the series. It is just these properties, magnetic and chemical, for which the Moessbauer effect is a valuable probe, sensitive to the magnetic and electric environment of an atom. The rare-earth series has been a particularly fruitful region in terms of the number of elements which have been shown to exhibit the Moessbauer effect, and for this reason the exploitation of the Moessbauer effect to yield new solid-state and chemical information on the rare earths is a highly active field of research today. There is every reason to believe that the actinides can be similarly studied by the Moessbauer effect. 43 refs, 6 figs, 4 tabs

Evaluation of actinide partitioning and transmutation

International Nuclear Information System (INIS)

1982-01-01

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

Complexation studies of actinides (U, Pu, Am) with linear polyamino-carboxylate ligands and sidero-chelates

International Nuclear Information System (INIS)

Nguyen, L.V.

2010-01-01

As part of our research endeavour aimed at developing and improving decontamination processes of wastewater containing alpha emitters, physico-chemical complexation studies of actinides (U, Pu, Am) with organic open-chain ligands such as poly-aminocarboxylic acids (H 4 EDTA) and sidero-chelates (di-hydroxamic acids and desferrioxamine B) have been carried out. Gaining a clear understanding of the coordination properties of the targeted actinides is an essential step towards the selection of the most appropriate chelating agents that will exhibit high uptake efficiencies. EXAFS (Extended X-ray Absorption Fine Structure) measurements at the ESRF synchrotron enabled to elucidate the coordination scheme of uranium and plutonium complexes. Solution thermodynamic investigations were intended to provide valuable information about the nature and the stability of the uranium(VI) and americium(III) complexes prevailing at a given pH in solution. The set of stability constants determined from potentiometric and UV-visible spectrophotometric titrations, allowed to predict the speciation of the selected actinides in presence of the aforementioned ligands and to determine the pH range required for achieving 'ultimate' decontamination. (author) [fr

Actinide-specific complexing agents: their structural and solution chemistry

International Nuclear Information System (INIS)

Raymond, K.N.; Freeman, G.E.; Kappel, M.J.

1983-07-01

The synthesis of a series of tetracatecholate ligands designed to be specific for Pu(IV) and other actinide(IV) ions has been achieved. Although these compounds are very effective as in vivo plutonium removal agents, potentiometric and voltammetric data indicate that at neutral pH full complexation of the Pu(IV) ion by all four catecholate groups does not occur. Spectroscopic results indicate that the tetracatecholates, 3,4,3-LICAMS and 3,4,3-LICAMC, complex Am(III). The Am(IV)/(III)-catecholate couple (where catecholate = 3,4,3-LICAMS or 3,4,3-LICAMC) is not observed, but may not be observable due to the large currents associated with ligand oxidation. However, within the potential range where ligand oxidation does not occur, these experiments indicate that the reduction potential of free Am(IV)/(III) is probably greater than or equal to + 2.6 V vs NHE or higher. Proof of the complexation of americium in the trivalent oxidation state by 3,4,3-LICAMS and 3,4,3-LICAMC elimates the possibility of tetracatholates stabilizing Am(IV) in vivo

Structural trends in a series of isostructural lanthanide-copper metallacrown sulfates (Ln(III) = Pr, Nd, Sm, Eu, Gd, Dy and Ho): hexaaquapentakis[μ3-glycinehydroxamato(2-)]sulfatopentacopper(II)lanthanide(III) heptaaquapentakis[μ3-glycinehydroxamato(2-)]sulfatopentacopper(II)lanthanide(III) sulfate hexahydrate.

Science.gov (United States)

Pavlishchuk, Anna V; Kolotilov, Sergey V; Fritsky, Igor O; Zeller, Matthias; Addison, Anthony W; Hunter, Allen D

2011-07-01

The seven isostructural complexes, [Cu(5)Ln(C(2)H(4)N(2)O(2))(5)(SO(4))(H(2)O)(6.5)](2)(SO(4))·6H(2)O, where Ln(III) = Pr, Nd, Sm, Eu, Gd, Dy and Ho, are representatives of the 15-metallacrown-5 family. Each dianion of glycinehydroxamic acid (GlyHA) links two Cu(II) cations forming a cyclic [CuGlyHA](5) frame. The Ln(III) cations are located at the centre of the [CuGlyHA](5) rings and are bound by the five hydroxamate O atoms in the equatorial plane. Five water molecules are coordinated to Cu(II) cations, and one further water molecule, located close to an inversion centre between two adjacent [Cu(5)Ln(GlyHA)(5)](2+) cations, is disordered around this inversion centre and coordinated to a Cu(II) cation of either the first or second metallacrown ether. Another water molecule and one of the two crystallographically independent sulfate anions are coordinated, the latter in a bidentate fashion, to the Ln(III) cation in the axial positions. The second sulfate anion is not coordinated to the cation, but is located in an interstitial position on a crystallographic inversion centre, thus leading to disorder of the O atoms around the centre of inversion. The Ln-O bond distances follow the trend of the lanthanide contraction. The apical Ln-O bond distances are very close to the sums of the ionic radii. However, the Ln-O distances within the metallacrown units are slightly compressed and the Ln(III) cations protrude significantly from the plane of the otherwise flat metallacrown ligand, thus indicating that the cavity is somewhat too small to accommodate the Ln(III) ions comfortably. This effect decreases with the size of the lanthanide cation from complex (I) (Ln(III) = Pr; 0.459) to complex (VII) (Ln(III) = Ho; 0.422), which indicates that the smaller lanthanide cations fit the cavity of the pentacopper metallacrown ring better than the larger ones. The diminished contraction of Ln-O distances within the metallacrown planes leads to an aniostropic contraction of the unit

Comparative studies of actinide and sub-actinide fission cross section calculation from MCNP6 and TALYS

International Nuclear Information System (INIS)

Perkasa, Y. S.; Waris, A.; Kurniadi, R.; Su'ud, Z.

2014-01-01

Comparative studies of actinide and sub-actinide fission cross section calculation from MCNP6 and TALYS have been conducted. In this work, fission cross section resulted from MCNP6 prediction will be compared with result from TALYS calculation. MCNP6 with its event generator CEM03.03 and LAQGSM03.03 have been validated and verified for several intermediate and heavy nuclides fission reaction data and also has a good agreement with experimental data for fission reaction that induced by photons, pions, and nucleons at energy from several ten of MeV to about 1 TeV. The calculation that induced within TALYS will be focused mainly to several hundred MeV for actinide and sub-actinide nuclides and will be compared with MCNP6 code and several experimental data from other evaluator

Influence of additives on the structure and microstructure of lanthanides and actinides oxalates

International Nuclear Information System (INIS)

Haidon, Blaise; Vitart, Anne-Lise; Rivenet, Murielle; Arab-Chapelet, Benedicte; Roussel, Pascal; Delahaye, Thibaud; Grandjean, Stephane; Abraham, Francis

2015-07-01

Oxalic conversion is a well-known process in the nuclear industry where it is used for precipitating plutonium as an oxalate thereafter calcinated into an oxide. As there is a strong relationship between the morphology of the oxalate precursor and that of the resulting oxide, it is of interest to control the oxalate structure and microstructure during the precipitation step. The influence of additives on the precipitation of neodymium (III) oxalates, non-radioactive analogs of actinides (III) oxalates, was explored. With the use of nitrilotri-methylphosphonic acid (NTMP), the structure and microstructure of the neodymium oxalates are different from that obtained without additive. (authors)

Liquid–liquid extraction of Pu(IV), U(VI) and Am(III) using malonamide in room temperature ionic liquid as diluent

International Nuclear Information System (INIS)

Rout, Alok; Venkatesan, K.A.; Srinivasan, T.G.; Vasudeva Rao, P.R.

2012-01-01

Highlights: ► Extraction of actinides using malonamide in room temperature ionic liquid. ► High distribution ratios of actinides in room temperature ionic liquid. ► Ion exchange mechanism. ► Stoichiometry of extraction. ► High separation factors of U(VI) and Pu(IV) over Am(III) and fission products. - Abstract: The extraction behavior of U(VI), Pu(IV) and Am(III) from nitric acid medium by a solution of N,N-dimethyl-N,N-dioctyl-2-(2-hexyloxyethyl)malonamide (DMDOHEMA) in the room temperature ionic liquid, 1–butyl–3–methylimidazolium bis(trifluoromethanesulfonyl)imide (C 4 mimNTf 2 ), was studied. The distribution ratio of these actinides in DMDOHEMA/C 4 mimNTf 2 was measured as a function of various parameters such as the concentration of nitric acid, DMDOHEMA, NTf 2 − , alkyl chain length of ionic liquid. The extraction of actinides in the absence of DMDOHEMA was insignificant and the distribution ratio achieved in conjunction with C 4 mimNTf 2 , was remarkable. The separation factor of U(VI) and Pu(IV) achieved with the use of DMDOHEMA, ionic liquid was compared with Am(III) and other fission products. The stoichiometry of the metal-solvate was determined to be 1:2 for U(VI) and Pu(IV) and 1:3 for Am(III).

Actinide nanoparticle research

International Nuclear Information System (INIS)

Kalmykov, Stepan N.; Denecke, Melissa A.

2011-01-01

This is the first book to cover actinide nano research. It is of interest both for fundamental research into the chemistry and physics of f-block elements as well as for applied researchers such as those studying the long-term safety of nuclear waste disposal and developing remediation strategies. The authors cover important issues of the formation of actinide nano-particles, their properties and structure, environmental behavior of colloids and nanoparticles related to the safe disposal of nuclear wastes, modeling and advanced methods of characterization at the nano-scale. (orig.)

Burning minor actinides in a HTR energy spectrum

International Nuclear Information System (INIS)

Pohl, Christoph; Rütten, H. Jochem

2012-01-01

Highlights: ► Burn-up analysis for varying plutonium/minor actinide fuel compositions. ► The influence of varying heavy metal fuel element loads is investigated. ► Significant burn-up via radiative capture and subsequently fission is observed. ► Difference observed between fuel element burn-up and total actinide burning rate. - Abstract: The generation of nuclear energy by means of the existing nuclear reactor systems is based mainly on the fission of U-235. But this comes along with the capture of neutrons by the U-238 faction and results in a build-up of plutonium isotopes and minor actinides as neptunium, americium and curium. These actinides are dominant for the long time assessment of the radiological risk of a final disposal therefore a minimization of the long living isotopes is aspired. Burning the actinides in a high temperature helium cooled graphite moderated reactor (HTR) is one of these options. The use of plutonium isotopes to sustain the criticality of the system is intended to avoid on the one hand highly enriched uranium because of international regulations and on the other hand low enriched uranium because of the build up of new actinides from neutron capture in the U-238 fraction. Because initial minor actinide isotopes are typically not fissionable by thermal neutrons the idea is to fission instead the intermediate isotopes generated by the first neutron capture. This paper comprises calculations for plutonium/minor actinides/thorium fuel compositions and their correlated final burn-up for a generic pebble bed HTR based on the reference design of the 400 MW PBMR. In particular the cross sections and the neutron balance of the different minor actinide isotopes in the higher thermal energy spectrum of a HTR will be discussed. For a fuel mixture of plutonium and minor actinides a significant burn-up of these actinides up to 20% can be achieved but at the expense of a higher residual fraction of plutonium in the burned fuel. Combining

Development of a system for simultaneous - sequential determinations of major and minor actinides (Th, Np, U, Pu, Am, Cm) by on-line extraction chromatography - ion concentration - inductively coupled plasma mass spectrometry

International Nuclear Information System (INIS)

Trivellone, E.; Mariani, M.; Carlos-Marquez, R.; Aldave de las Heras, L.; Betti, M.; )

2009-01-01

Full text: Because of the great complexity and time consuming of traditional methods for actinides determination, a procedure for their simultaneous and sequential separation and quantification was developed. A complete circuit constituted by three analytical chromatographic columns packed with TEVA, UTEVA and TRU resins (Eichrom Inc) for retention of tetra-, hexa- and tri-valent actinides and three cation concentrator columns TCC-II (from Dionex Corporation) connected by six (4-way and 6-way) valves is coupled on-line to an ICPMS detector. The use of TCC-II columns just prior of the ICPMS determination allows to improve sensitivity and detection limits down to the ng/l level. The use of a coupled HPLC to an ICPMS system enables the complete analysis of all the six actinides in almost 2 hours. (author)

Actinides reduction by recycling in a thermal reactor

International Nuclear Information System (INIS)

Ramirez S, J. R.; Martinez C, E.; Balboa L, H.

2014-10-01

This work is directed towards the evaluation of an advanced nuclear fuel cycle in which radioactive actinides could be recycled to remove most of the radioactive material; firstly a production reference of actinides in standard nuclear fuel of uranium at the end of its burning in a BWR reactor is established, after a fuel containing plutonium is modeled to also calculate the actinides production in MOX fuel type. Also it proposes a design of fuel rod containing 6% of actinides in a matrix of uranium from the tails of enrichment, then four standard uranium fuel rods are replaced by actinides rods to evaluate the production and transmutation thereof, the same procedure was performed in the fuel type MOX and the end actinide reduction in the fuel was evaluated. (Author)

Chemical interaction of tetravalent actinides simulators and the engineering barrier

International Nuclear Information System (INIS)

Chain, Pablo; Alba, Maria D.; Castro, Miguel A.; Pavon, Esperanza; Mar Orta, M.

2010-01-01

Document available in extended abstract form only. The Deep Geological Repository (DGR) is the most internationally accepted option for the storage of high radioactive wastes. This confinement is based on the Multi-barrier Concept where the engineered barrier is a crucial safety wise. Nowadays, bentonite is accepted as the best argillaceous material in the engineered barrier of DGR. Additionally to its well-known physical role, a chemical interaction between lutetium, as actinide simulator, and the smectite has been demonstrated. The existence of a reaction mechanism, which was not previously described, based on the chemical interaction between the lanthanide cations and the orthosilicate anions of the lamellar structure has been identified. This finding has aroused the interest of the scientific community because lanthanides are used as simulators of high activity radionuclide (HAR) in agreement with the guidelines established in the bibliography. It has been observed that in conditions of moderate temperature and pressure a chemical interaction exists between smectites and rare earth elements (RE) and phases of insoluble di-silicate, RE 2 Si 2 O 7 , which would immobilize RE, are generated. It is remarkable that the reaction extends to all the set of the smectites, although they do not display the same reactivity, the saponite being the most reactive. The main isotopes present in the HLW belong to the actinide elements Np, Pu, Am and Cm, in addition to uranium generated by neutron capture during the fuel combustion process. The study of the mobilization of actinide (IV) thorough the bentonite barrier is limited because of their radioactivity. However, U(IV), Np(IV), Pu(IV) and Th(IV) can be simulated by the stable isotopes of the Zr(IV) and Hf(IV), because they exhibit ionic radius and physicochemical properties very similar to those of the actinide elements. It is the main objective of this research to investigate the chemical interaction of Zr(IV) as actinide

Potential carcinogenic effects of actinides in the environment

International Nuclear Information System (INIS)

Harley, N.H.; Pasternack, B.S.

1979-01-01

Inhalation of alpha emitting actinides delivers a dose to critical cancer sites in the human body. These sites are the bronchial epithelium and cells near bone surfaces. Inhalation of the naturally occurring actinides uranium and thorium in resuspended soil in the air results in a continuous exposure for the global population of about 0.1 fCi/m 3 for each of these actinides. The highest dose is from the natural actinide 230 Th. Over 50 yr, the dose to bronchial epithelium is 0.05 mrad and to bone surfaces 0.4 mrad. In the case of accidental environmental contamination (e.g. near a nuclear fuel reprocessing plant) the man-made actinides plutonium, americium and curium could deliver about the same alpha dose to these sites if the soil is contaminated to the same level as the natural actinides (approximately 1 pCi/g). Two nuclear accidents have already produced contamination of about this level. Exposures in this case, however, are to small local populations compared with global exposure for the natural actinides. Significant enhancement of the natural radioactive actinide pollution by combustion of all types of fossil fuel is suspected but not enough data are available to estimate total population doses. (author)

End point control of an actinide precipitation reactor

International Nuclear Information System (INIS)

Muske, K.R.

1997-01-01

The actinide precipitation reactors in the nuclear materials processing facility at Los Alamos National Laboratory are used to remove actinides and other heavy metals from the effluent streams generated during the purification of plutonium. These effluent streams consist of hydrochloric acid solutions, ranging from one to five molar in concentration, in which actinides and other metals are dissolved. The actinides present are plutonium and americium. Typical actinide loadings range from one to five grams per liter. The most prevalent heavy metals are iron, chromium, and nickel that are due to stainless steel. Removal of these metals from solution is accomplished by hydroxide precipitation during the neutralization of the effluent. An end point control algorithm for the semi-batch actinide precipitation reactors at Los Alamos National Laboratory is described. The algorithm is based on an equilibrium solubility model of the chemical species in solution. This model is used to predict the amount of base hydroxide necessary to reach the end point of the actinide precipitation reaction. The model parameters are updated by on-line pH measurements

On the suitability of lanthanides as actinide analogs

International Nuclear Information System (INIS)

Raymond, Kenneth; Szigethy, Geza

2008-01-01

With the current level of actinide materials used in civilian power generation and the need for safe and efficient methods for the chemical separation of these species from their daughter products and for long-term storage requirements, a detailed understanding of actinide chemistry is of great importance. Due to the unique bonding properties of the f-elements, the lanthanides are commonly used as structural and chemical models for the actinides, but differences in the bonding between these 4f and 5f elements has become a question of immediate applicability to separations technology. This brief overview of actinide coordination chemistry in the Raymond group at UC Berkeley/LBNL examines the validity of using lanthanide analogs as structural models for the actinides, with particular attention paid to single crystal X-ray diffraction structures. Although lanthanides are commonly accepted as reasonable analogs for the actinides, these comparisons suggest the careful study of actinide materials independent of their lanthanide analogs to be of utmost importance to present and future efforts in nuclear industries. (authors)

Review of actinide decorporation with chelating agents

Energy Technology Data Exchange (ETDEWEB)

Ansoborlo, E. [CEA Valrho, Dir. de l' Energie Nucleaire (DEN/DRCP/CETAMA), 30 - Marcoule (France); Amekraz, B.; Moulin, Ch. [CEA Saclay, Dept. de Physico-Chimie (DEN/DPC/SECR), 91 - Gif sur Yvette (France); Moulin, V. [CEA Saclay, Dir. du Developpement et de l' Innovation Nucleares (DEN/DDIN/MR), 91 - Gif Sur Yvette (France); Taran, F. [CEA Saclay (DSV/DBJC/SMMCB), 91 - Gif-sur-Yvette (France); Bailly, Th.; Burgada, R. [Centre National de la Recherche Scientifique (CNRS/LCSB/UMR 7033), 93 - Bobigny (France); Henge-Napoli, M.H. [CEA Valrho, Site de Marcoule (INSTN), 30 (France); Jeanson, A.; Den Auwer, Ch.; Bonin, L.; Moisy, Ph. [CEA Valrho, Dir. de l' Energie Nucleaire (DEN/DRCP/SCPS), 30 - Marcoule (France)

2007-10-15

In case of accidental release of radionuclides in a nuclear facility or in the environment, internal contamination (inhalation, ingestion or wound) with actinides represents a severe health risk to human beings. It is therefore important to provide effective chelation therapy or decorporation to reduce acute radiation damage, chemical toxicity, and late radiation effects. Speciation governs bioavailability and toxicity of elements and it is a prerequisite tool for the design and success of new ligands or chelating agents. The purpose of this review is to present the state-of-the-art of actinide decorporation within biological media, to recall briefly actinide metabolism, to list the basic constraints of actinide-ligand for development, to describe main tools developed and used for decorporation studies, to review mainly the chelating agents tested for actinides, and finally to conclude on the future trends in this field. (authors)

Transmutation of waste actinides in light water reactors

International Nuclear Information System (INIS)

Gorrell, T.C.

1979-04-01

Actinide recycle and transmutation calculations were made for three irradiation options of a light water reactor (LWR). The cases considered were: all actinides recycled in regular uranium fuel assemblies; transuranic actinides recycled in separate MOX assemblies with 235 U enrichment of uranium; and transuranic actinides recycled in separate MOX assemblies with plutonium enrichment of natural uranium. When all actinides were recycled in a uniform lattice, the transuranic inventory after ten recycles was 38% of the inventory accumulated without recycle. When the transuranics from two regular uranium assemblies were combined with those recycled from a MOX assembly, the transuranic inventory was reduced 50% after five recycles

Chemical compatibility of HLW borosilicate glasses with actinides

International Nuclear Information System (INIS)

Walker, C.T.; Scheffler, K.; Riege, U.

1978-11-01

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 23 0 C and 115 0 C. (orig.) [de

Linear free energy relationship applied to trivalent cations with lanthanum and actinium oxide and hydroxide structure

International Nuclear Information System (INIS)

Ragavan, Anpalaki J.

2006-01-01

Linear free energy relationships for trivalent cations with crystalline M 2 O 3 and, M(OH) 3 phases of lanthanides and actinides were developed from known thermodynamic properties of the aqueous trivalent cations, modifying the Sverjensky and Molling equation. The linear free energy relationship for trivalent cations is as ΔG f,MvX 0 =a MvX ΔG n,M 3+ 0 +b MvX +β MvX r M 3+ , where the coefficients a MvX , b MvX , and β MvX characterize a particular structural family of MvX, r M 3+ is the ionic radius of M 3+ cation, ΔG f,MvX 0 is the standard Gibbs free energy of formation of MvX and ΔG n,M 3+ 0 is the standard non-solvation free energy of the cation. The coefficients for the oxide family are: a MvX =0.2705, b MvX =-1984.75 (kJ/mol), and β MvX =197.24 (kJ/molnm). The coefficients for the hydroxide family are: a MvX =0.1587, b MvX =-1474.09 (kJ/mol), and β MvX =791.70 (kJ/molnm).

Investigations on synthesis, coordination behaviour and actinide recovery of unexplored phosphine oxides

International Nuclear Information System (INIS)

Veerashekhar Goud, E.; Pavankumar, B.B.; Das, Dhrubajyothi

2016-01-01

The search for the development of an optimum extractant for effective separation of a particular metal from a mixture is an active field of research in both chemistry and chemical engineering. These extractants find extensive application in extractive metallurgy and in nuclear fuel cycle (for the separation of actinides from other fission products). In the case of the latter, solvent extraction and ion exchange are two widely employed separation techniques. In this connection, the present paper reports synthesis and structural characterization of various new phosphine oxide derivatives. The coordination behavior of these ligands is studied with some selected lanthanides and actinides shows the proposed structures of La(III) and Th(IV) metal complexes. The purity and structural characterization of the ligands and their corresponding metal complexes are analyzed by various analytical and spectroscopic techniques. Additionally, we have applied Density functional theory (DFT) calculations to understand the electronic structure of some metal complexes formed during the extraction process. (author)

Spectroscopic studies on the interaction of europium(III) and curium(III) with components of the human mucosa

Energy Technology Data Exchange (ETDEWEB)

Wilke, Claudia; Barkleit, Astrid [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Div. Chemistry of the F-Elements

2016-07-01

To evaluate the health risks of lanthanides (Ln) and radiotoxic actinides (An) in case of ingestion accidents etc., investigations into the chemical reactions of these metals in the human gastrointestinal tract are necessary. Our previous study revealed that mucin, an important part of the protective mucosa layer in the digestive system, shows a strong interaction with Eu(III). Based on these results, the present study focuses on the components of this glycoprotein and identified N-acetylneuraminic acid (NANA) as the dominant binding carbohydrate of mucin. TRLFS measurements suggest the formation of a 1: 1 complex with log β of 3.2 ± 0.1 for Eu(III) and 3.3 ± 0.1 for Cm(III), respectively.

Advances in computational actinide chemistry in China

Energy Technology Data Exchange (ETDEWEB)

Wang, Dongqi; Wu, Jingyi; Chai, Zhifang [Chinese Academy of Sciences, Beijing (China). Multidisciplinary Initiative Center; Su, Jing [Chinese Academy of Sciences, Shanghai (China). Div. of Nuclear Materials Science and Engineering; Li, Jun [Tsinghua Univ., Beijing (China). Dept. of Chemistry and Laboratory of Organic Optoelectronics and Molecular Engineering

2014-04-01

The advances in computational actinide chemistry made in China are reviewed. Several areas relevant to chemistry of actinides in gas, liquid, and solid phases have been explored. However, we limit the scope to selected contributions in the chemistry of molecular actinide systems in gas and liquid phases. These studies may be classified into two categories: treatment of relativistic effects, which cover the development of two- and four-component Hamiltonians and the optimization of relativistic pseudopotentials, and the applications of theoretical methods in actinide chemistry. The applications include (1) the electronic structures of actinocene, noble gas complexes, An-C multiple bonding compounds, uranyl and its isoelectronic species, fluorides and oxides, molecular systems with metal-metal bonding in their isolated forms (U{sub 2}, Pu{sub 2}) and in fullerene (U{sub 2} rate at C{sub 60}), and the excited states of actinide complexes; (2) chemical reactions, including oxidation, hydrolysis of UF{sub 6}, ligand exchange, reactivities of thorium oxo and sulfido metallocenes, CO{sub 2}/CS{sub 2} functionalization promoted by trivalent uranium complex; and (3) migration of actinides in the environment. A future outlook is discussed. (orig.)

Transmutation of minor actinide using thorium fueled BWR core

International Nuclear Information System (INIS)

Susilo, Jati

2002-01-01

One of the methods to conduct transmutation of minor actinide is the use of BWR with thorium fuel. Thorium fuel has a specific behaviour of producing a little secondary minor actinides. Transmutation of minor actinide is done by loading it in the BWR with thorium fuel through two methods, namely close recycle and accumulation recycle. The calculation of minor actinide composition produced, weigh of minor actinide transmuted, and percentage of reminder transmutation was carried SRAC. The calculations were done to equivalent cell modeling from one fuel rod of BWR. The results show that minor actinide transmutation is more effective using thorium fuel than uranium fuel, through both close recycle and accumulation recycle. Minor actinide transmutation weight show that the same value for those recycle for 5th recycle. And most of all minor actinide produced from 5 unit BWR uranium fuel can transmuted in the 6 t h of close recycle. And, the minimal value of excess reactivity of the core is 12,15 % Δk/k, that is possible value for core operation

Actinide recovery from waste and low-grade sources

International Nuclear Information System (INIS)

Navratil, J.D.; Schulz, W.W.

1982-01-01

Actinide and nuclear fuel cycle operations generate a variety of process waste streams. New methods are needed to remove and recover actinides. More interest is also being expressed in recovering uranium from oceans, phosphoric acid, and other low grade sources. To meet the need for an up-to-date status report in the area of actinide recovery from waste and low grade sources, these papers were brought together. The papers provide an authoritative, in-depth coverage of an important area of nuclear and industrial and engineering chemistry which cover the following topics: uranium recovery from oceans and phosphoric acid; recovery of actinides from solids and liquid wastes; plutonium scrap recovery technology; and other new developments in actinide recovery processes

Transmutation of LWR waste actinides in thermal reactors

International Nuclear Information System (INIS)

Gorrell, T.C.

1979-01-01

Recycle of actinides to a reactor for transmutation to fission products is being considered as a possible means of waste disposal. Actinide transmutation calculations were made for two irradiation options in a thermal (LWR) reactor. The cases considered were: all actinides recycled in regular uranium fuel assemblies, and transuranic actinides recycled in separate mixed oxide (MOX) assemblies. When all actinides were recycled in a uranium lattice, a reduction of 62% in the transuranic inventory was achieved after 10 recycles, compared to the inventory accumulated without recycle. When the transuranics from 2 regular uranium assemblies were combined with those recycled from a MOX assembly, the transuranic inventory was reduced 50% after 5 recycles

Actinide complexation kinetics: rate and mechanism of dioxoneptunium (V) reaction with chlorophosphonazo III

International Nuclear Information System (INIS)

Fugate, G.; Feil-Jenkins, J.F.; Sullivan, J.C.; Nash, K.L.

1996-12-01

Rates of complex formation and dissociation in NpO 2 + - Chlorophosphonazo III (2,7-bis(4-chloro-2-phosphonobenzeneazo)-1,8- dihydroxynapthalene-3,6-disulfonic acid)(CLIII) were investigated by stopped-flow spectrophotometry. Also, limited studies were made of the rates of reaction of La 3+ , Eu 3+ , Dy 3+ , and Fe 3+ with CLIII. Rate determining step in each system is an intramolecular process, the NpO 2 + -CLIII reaction proceeding by a first order approach to equilibrium in the acid range from 0.1 to 1.0 M. Complex formation occurs independent of acidity, while both acid dependent and independent dissociation pathways are observed. Activation parameters for the complex formation reaction are ΔH=46.2±0.3 kJ/m and ΔS=7± J/mK (I=1.0 M); these for the acid dependent and independent dissociation pathways are ΔH=38.8±0.6 kJ/m, ΔS=-96±18 J/mK, ΔH=70.0± kJ/m, and ΔS=17±1 J/mK, respectively. An isokinetic relationship is observed between the activation parameters for CLIII complex formation with NpO 2 + , UO 2 2+ , Th 4+ , and Zr 4+ . Rates of CLIII complex formation reactions for Fe 3+ , Zr 4+ , NpO 2 + , UO 2 2+ , Th 4+ , La 3+ , Eu 3+ , and Dy 3+ correlate with cation radius rather than charge/radius ratio

Solubility of actinides and surrogates in nuclear glasses

International Nuclear Information System (INIS)

Lopez, Ch.

2003-01-01

The nuclear wastes are currently incorporated in borosilicate glass matrices. The resulting glass must be perfectly homogeneous. The work discussed here is a study of actinide (thorium and plutonium) solubility in borosilicate glass, undertaken to assess the extent of actinide solubility in the glass and to understand the mechanisms controlling actinide solubilization. Glass specimens containing; actinide surrogates were used to prepare and optimize the fabrication of radioactive glass samples. These preliminary studies revealed that actinide Surrogates solubility in the glass was enhanced by controlling the processing temperature, the dissolution kinetic of the surrogate precursors, the glass composition and the oxidizing versus reducing conditions. The actinide solubility was investigated in the borosilicate glass. The evolution of thorium solubility in borosilicate glass was determined for temperatures ranging from 1200 deg C to 1400 deg C.Borosilicate glass specimens containing plutonium were fabricated. The experimental result showed that the plutonium solubility limit ranged from 1 to 2.5 wt% PuO 2 at 1200 deg C. A structural approach based on the determination of the local structure around actinides and their surrogates by EXAFS spectroscopy was used to determine their structural role in the glass and the nature of their bonding with the vitreous network. This approach revealed a correlation between the length of these bonds and the solubility of the actinides and their surrogates. (author)

Nuclear waste forms for actinides

Science.gov (United States)

Ewing, Rodney C.

1999-01-01

The disposition of actinides, most recently 239Pu from dismantled nuclear weapons, requires effective containment of waste generated by the nuclear fuel cycle. Because actinides (e.g., 239Pu and 237Np) are long-lived, they have a major impact on risk assessments of geologic repositories. Thus, demonstrable, long-term chemical and mechanical durability are essential properties of waste forms for the immobilization of actinides. Mineralogic and geologic studies provide excellent candidate phases for immobilization and a unique database that cannot be duplicated by a purely materials science approach. The “mineralogic approach” is illustrated by a discussion of zircon as a phase for the immobilization of excess weapons plutonium. PMID:10097054

Fusion barrier characteristics of actinides

Science.gov (United States)

Manjunatha, H. C.; Sridhar, K. N.

2018-03-01

We have studied fusion barrier characteristics of actinide compound nuclei with atomic number range 89 ≤ Z ≤ 103 for all projectile target combinations. After the calculation of fusion barrier heights and positions, we have searched for their parameterization. We have achieved the empirical formula for fusion barrier heights (VB), positions (RB), curvature of the inverted parabola (ħω) of actinide compound nuclei with atomic number range 89 ≤ Z ≤ 103 for all projectile target combinations (6 projectile target combinations. The values produced by the present formula are also compared with experiments. The present pocket formula produces fusion barrier characteristics of actinides with the simple inputs of mass number (A) and atomic number (Z) of projectile-targets.

Programme and Abstracts. 38. Journees des Actinides together with the 7. School on the Physics and Chemistry of the Actinides

Energy Technology Data Exchange (ETDEWEB)

NONE

2008-07-01

Journees des Actinides (JdA) is a traditional informal actinide forum, including physics, chemistry, and materials research. It regularly brings together experts from fields involved, taking place in a very informal way, emphasizing exchanges and discussions on current issues in actinide science. At the 38{sup th} JdA (10-15 April 2008; Wroclaw, Poland) scientific communications on the following topics on physics and chemistry of the actinides were presented: (a) inorganic and organometallic chemistry; (b) strongly correlated behaviour, superconductivity, quantum criticality; (c) materials science; (d) theory, electronic structure; (e) nuclear fuel cycle, environment.

Programme and Abstracts. 38. Journees des Actinides together with the 7. School on the Physics and Chemistry of the Actinides

International Nuclear Information System (INIS)

2008-01-01

Journees des Actinides (JdA) is a traditional informal actinide forum, including physics, chemistry, and materials research. It regularly brings together experts from fields involved, taking place in a very informal way, emphasizing exchanges and discussions on current issues in actinide science. At the 38 th JdA (10-15 April 2008; Wroclaw, Poland) scientific communications on the following topics on physics and chemistry of the actinides were presented: (a) inorganic and organometallic chemistry; (b) strongly correlated behaviour, superconductivity, quantum criticality; (c) materials science; (d) theory, electronic structure; (e) nuclear fuel cycle, environment

Extraction Separation of Am(III) and Eu(III) with Thermo-sensitive Gel introducing TPEN Derivatives

International Nuclear Information System (INIS)

Kenji Takeshita; Yoshio Nakano; Tatsuro Matsumura; Atsunori Mori

2008-01-01

A thermal-swing chromatographic process using a thermo-sensitive gel co-polymerized with NIPA (N-isopropyl-acrylamide) and TPPEN (N,N,N',N'-tetrakis(4-propenyl-oxy-2-pyridyl-methyl)ethylenediamine) was studied for the separation of Am(III) from Eu(III). First, the radiolysis of the TPPEN-NIPA gel was tested by the γ-ray irradiation and the α nuclide adsorption. The extraction separation of Am(III) was not influenced in the radioactive environment of the proposed process. Next, the TPPEN-NIPA gel was immobilized in porous silica particles and the applicability of the gel-immobilized silica to the proposed process was tested. Am(III) was extracted selectively in the gel-immobilized silica at 5 deg. C and the separation factor of Am(III) over Eu(III) was evaluated to be 3.7. The distribution ratio of Am(III) was reduced to less than 1/20 by increasing temperature from 5 deg. C to 40 deg. C. These results indicate that the TPPEN-NIPA gel is applicable to the thermal-swing chromatographic process for the minor actinide recovery. (authors)

Actinide Source Term Program, position paper. Revision 1

International Nuclear Information System (INIS)

Novak, C.F.; Papenguth, H.W.; Crafts, C.C.; Dhooge, N.J.

1994-01-01

The Actinide Source Term represents the quantity of actinides that could be mobilized within WIPP brines and could migrate with the brines away from the disposal room vicinity. This document presents the various proposed methods for estimating this source term, with a particular focus on defining these methods and evaluating the defensibility of the models for mobile actinide concentrations. The conclusions reached in this document are: the 92 PA open-quotes expert panelclose quotes model for mobile actinide concentrations is not defensible; and, although it is extremely conservative, the open-quotes inventory limitsclose quotes model is the only existing defensible model for the actinide source term. The model effort in progress, open-quotes chemical modeling of mobile actinide concentrationsclose quotes, supported by a laboratory effort that is also in progress, is designed to provide a reasonable description of the system and be scientifically realistic and supplant the open-quotes Inventory limitsclose quotes model

Limitations of actinide recycle and waste disposal consequences

International Nuclear Information System (INIS)

Baetsle, L.H.; Raedt, C. de

1994-01-01

The paper emphasizes the impact of Light Water Reactor - Mixed Oxides introduction on the subsequent actinide management and fate of reprocessed and depleted uranium. The spent fuel from LWR-MOX contains in principle 75% of the initially produced plutonium. This new source term has to be considered together with the minor actinides from the conventional reprocessing. Subsequent LWR-MOX reprocessing in the first step in a very long term Pu + minor actinides management. Recycling of Pu + minor actinides in fast reactors to significantly reduce the Pu and minor actinides inventory (e.g. a factor of 10) is a very slow process which requires the development and operation of a large park of actinide burner reactors during an extended period of time. The overall feasibility of the P and T option will greatly depend on the massive introduction during the next century of fast neutron reactors as a replacement to the present LWR generation of nuclear power plants. (authors). 11 refs., 6 tabs., 2 figs

33rd Actinide Separations Conference

Energy Technology Data Exchange (ETDEWEB)

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.

33rd Actinide Separations Conference

International Nuclear Information System (INIS)

McDonald, L.M.; Wilk, P.A.

2009-01-01

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.

Hydrothermal decomposition of actinide(IV oxalates: a new aqueous route towards reactive actinide oxide nanocrystals

Directory of Open Access Journals (Sweden)

Walter Olaf

2016-01-01

Full Text Available The hydrothermal decomposition of actinide(IV oxalates (An= Th, U, Pu at temperatures between 95 and 250 °C is shown to lead to the production of highly crystalline, reactive actinide oxide nanocrystals (NCs. This aqueous process proved to be quantitative, reproducible and fast (depending on temperature. The NCs obtained were characterised by X-ray diffraction and TEM showing their size to be smaller than 15 nm. Attempts to extend this general approach towards transition metal or lanthanide oxalates failed in the 95–250 °C temperature range. The hydrothermal decomposition of actinide oxalates is therefore a clean, flexible and powerful approach towards NCs of AnO2 with possible scale-up potential.

ACTINET - EU network of excellence for actinide sciences

International Nuclear Information System (INIS)

Gompper, K.

2006-01-01

ACTINET, the Network of Excellence for Actinide Sciences within the 6th EU Framework Program, was launched in March 2004 for an initial period of four years. A number of tools are available in ACTINET to serve the purposes of the project, i.e. stimulate and coordinate actinide research in Europe, promote integration, train young scientists and, in this way, ensure and enhance European competence. The large European actinide laboratories with their unique experimental and analytical equipment are available to scientists from Europe as so-called 'pool facilities' within the framework of joint research projects. Setting up a 'theoretical user lab' has turned out to be a promising way of exploiting the synergies of theory and experiment in various fields of actinide science. Joint research projects are supported within the network, working with actinides being made possible in the pool facilities. Training and instruction are ensured by seminars, workshops, and schools organized annually. In familiarizing young scientists with actinide work, ACTINET exercises training functions and contributes to ensuring and enhancing European competence in the field on the medium and long term. Even after only half of its term, ACTINET is developing into a live network, thus decisively contributing towards promoting, coordinating and integrating European actinide research. As actinides play a key role in the use of nuclear power, this benefits European industries, research centers, operators of nuclear power plants and nuclear facilities as well as licensing and regulatory authorities. (orig.)

Superconductivity in the actinides

International Nuclear Information System (INIS)

Smith, J.L.; Lawson, A.C.

1985-01-01

The trends in the occurrence of superconductivity in actinide materials are discussed. Most of them seem to show simple transition metal behavior. However, the superconductivity of americium proves that the f electrons are localized in that element and that ''actinides'' is the correct name for this row of elements. Recently the superconductivity of UBe 13 and UPt 3 has been shown to be extremely unusual, and these compounds fall in the new class of compounds now known as heavy fermion materials

A uranium-based UO{sub 2}{sup +}-Mn{sup 2+} single-chain magnet assembled trough cation-cation interactions

Energy Technology Data Exchange (ETDEWEB)

Mougel, Victor; Chatelain, Lucile; Hermle, Johannes; Pecaut, Jacques; Mazzanti, Marinella [Laboratoire de Reconnaissance Ionique et Chimie de Coordination, SCIB, UMR-E3 CEA-UJF, INAC, CEA-Grenoble (France); Caciuffo, Roberto; Colineau, Eric [European Commission, Joint Research Centre, Institute for Transuranium Elements, Karlsruhe (Germany); Tuna, Floriana [EPSRC UK EPR Facility, School of Chemistry and Photon Science Institute, The University of Manchester (United Kingdom); Magnani, Nicola [Institute of Nanotechnology, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen (Germany); Geyer, Arnaud de [Service General des Rayons X, SP2M, INAC, CEA-Grenoble (France)

2014-01-13

Single-chain magnets (SCMs) are materials composed of magnetically isolated one-dimensional (1D) units exhibiting slow relaxation of magnetization. The occurrence of SCM behavior requires the fulfillment of stringent conditions for exchange and anisotropy interactions. Herein, we report the synthesis, the structure, and the magnetic characterization of the first actinide-containing SCM. The 5f-3d heterometallic 1D chains [{[UO_2(salen)(py)][M(py)_4](NO_3)}]{sub n}, (M=Cd (1) and M=Mn (2); py=pyridine) are assembled trough cation-cation interaction from the reaction of the uranyl(V) complex [UO{sub 2}(salen)py][Cp*{sub 2}Co] (Cp*=pentamethylcyclopentadienyl) with Cd(NO{sub 3}){sub 2} or Mn(NO{sub 3}){sub 2} in pyridine. The infinite UMn chain displays a high relaxation barrier of 134 ±0.8 K (93 ±0.5 cm{sup -1}), probably as a result of strong intra-chain magnetic interactions combined with the high Ising anisotropy of the uranyl(V) dioxo group. It also exhibits an open magnetic hysteresis loop at T <6 K, with an impressive coercive field of 3.4 T at 2 K. (Copyright copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Extraction of Am (III) and Nd (III): comparison of TODGA and TEHDGA

International Nuclear Information System (INIS)

Gujar, R.B.; Murali, M.S.; Ansari, S.A.; Manchanda, V.K.

2009-01-01

Belonging to the class of extractants, diglycolamides which are recently explored and promising for actinide partitioning, two reagents (N, N, N', N'-tetraoctyl diglycolamide) TODGA and its isomerically substituted counterpart, (N, N, N', N'- tetraethylhexyl diglycolamide) TEHDGA after addition of suitable phase modifiers, Dihexyoctanamide and isodecanol respectively in dodecane have been compared in their extraction abilities for Am (III) and Nd (III) from nitric acid as well as simulated high-level waste solutions (SHLW) equivalent to HLW arising from PHWR fuel reprocessing. Both 0.1M TODGA + 0.5M DHOA and 0.2M TEHDGA + 30% isodecanol in dodecane display high distribution ratios for the trivalent metal ions of f-elements. Similarities and differences in their extraction are discussed. (author)

Reactor physics aspects of burning actinides in a nuclear reactor

International Nuclear Information System (INIS)

Hage, W.; Schmidt, E.

1978-01-01

A short review of the different recycling strategies of actinides other than fuel treated in the literature, is given along with nuclear data requirements for actinide build-up and transmutation studies. The effects of recycling actinides in a nuclear reactor on the flux distribution, the infinite neutron multiplication factor, the reactivity control system, the reactivity coefficients and the delayed neutron fraction are discussed considering a notional LWR or LMFBR as an Actinide Trasmutaton Reactor. Some operational problems of Actinide Transmutation reactors are mentioned, which are caused by the α-decay heat and the neutron sources of Actinide Target Elements

Actinide chemistry in the far field

International Nuclear Information System (INIS)

Livens, F.R.; Morris, K.; Parkman, R.; Moyes, L.

1996-01-01

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)

Atomistic modeling of the solid-state chemistry of actinide materials

Science.gov (United States)

Shuller, Lindsay C.

Materials that incorporate actinides are critical to the nuclear fuel cycle, either as nuclear fuels or nuclear waste forms. In this thesis, I examine four materials: i) ThO2-UO2 solid solutions, ii) binary ThO2-CeO2-ZrO2 solid solutions, iii) Np-doped studtite, iv) Np-doped boltwoodite. Computational methods, particularly density functional theory (DFT) calculations and Monte-Carlo (MC) simulations, are used to determine the energetics and structures of these actinide-bearing materials. The solid-solution behavior of nuclear fuels and nuclear waste forms indicate the thermodynamic stability of the material, which is important for understanding the in-reactor fuel properties and long-term stability of used fuel. The ThxU1-xO2 and ThxCe 1-xO2 binaries are almost completely miscible; however, DeltaGmix reveals a small tendency for the systems to exsolve (e.g., DeltaEexsoln(Th xU1-xO2) = 0.13 kJ/(mol cations) at 750 K). Kinetic hindrances (e.g., interfacial energy) may inhibit exsolution, especially at the low temperatures necessary to stabilize the nanoscale exsolution lamellae observed in the ThxU1-xO2 and Ce xZr1-xO2 binaries. Miscibility in the Zr-bearing binaries is limited. At 1400 °C, only 3.6 and 0.09 mol% ZrO2 is miscible in CeO2 and ThO2, respectively. The incorporation of minor amounts of Np5+,6+ into uranium alteration phases, e.g., studtite [UO2O2 (H2O)4] or boltwoodite [K(UO2)(SiO 3OH)(H2O)1.5] , may limit the mobility of aqueous neptunyl complexes released from oxidized nuclear fuels. Np6+-incorporation into studtite requires less energy than Np5+-incorporation (e.g., with source/sink = Np2O5/UO 3 DeltaEincorp(Np6+) = 0.42 eV and DeltaEincorp(Np5+) = 1.12 eV). In addition, Np6+ is completely miscible in studtite at room temperature with respect to a hypothetical Np6+-studtite. Electronic structure calculations provide insight into Np-bonding in studtite. The Np 5f orbitals are within the band gap of studtite, resulting in the narrowing of the band gap

Separations chemistry for actinide elements: Recent developments and historical perspective

International Nuclear Information System (INIS)

Nash, K.L.; Choppin, G.R.

1997-01-01

With the end of the cold war, the principal mission in actinide separations has changed from production of plutonium to cleanup of the immense volume of moderately radioactive mixed wastes which resulted from fifty years of processing activities. In order to approach the cleanup task from a proper perspective, it is necessary to understand how the wastes were generated. Most of the key separations techniques central to actinide production were developed in the 40's and 50's for the identification and production of actinide elements. Total actinide recovery, lanthanide/actinide separations, and selective partitioning of actinides from inert constituents are currently of primary concern. To respond to the modern world of actinide separations, new techniques are being developed for separations ranging from analytical methods to detect ultra-trace concentrations (for bioassay and environmental monitoring) to large-scale waste treatment procedures. In this report, the history of actinide separations, both the basic science and production aspects, is examined and evaluated in terms of contemporary priorities

1981 Annual Status Report. Plutonium fuels and actinide programme

International Nuclear Information System (INIS)

1981-01-01

In this 1981 report the work carried out by the European Institute for Transuranium elements is reviewed. Main topics are: operation limits of plutonium fuels: swelling of advanced fuels, oxide fuel transients, equation of state of nuclear materials; actinide cycle safety: formation of actinides (FACT), safe handling of plutonium fuel (SHAPE), aspects of the head-end processing of carbide fuel (RECARB); actinide research: crystal chemistry, solid state studies, applied actinide research

Ultratrace analysis of transuranic actinides by laser-induced fluorescence

Science.gov (United States)

Miller, S.M.

1983-10-31

Ultratrace quantities of transuranic actinides are detected indirectly by their effect on the fluorescent emissions of a preselected fluorescent species. Transuranic actinides in a sample are coprecipitated with a host lattice material containing at least one preselected fluorescent species. The actinide either quenches or enhances the laser-induced fluorescence of the preselected fluorescent species. The degree of enhancement or quenching is quantitatively related to the concentration of actinide in the sample.

Stabilization of actinides and lanthanides in unusually high oxidation states

International Nuclear Information System (INIS)

Eller, P.G.; Penneman, R.A.

1986-01-01

Chemical environments can be chosen which stabilize actinides and lanthanides in unusually high or low oxidation states and in unusual coordination. In many cases, one can rationalize the observed species as resulting from strong charge/size influences provided by specific sites in host lattices (e.g., Tb(IV) in BaTbO 3 or Am(IV) in polytungstate anions). In other cases, the unusual species can be considered from an acid-base viewpoint (e.g., U(III) in AsF 5 /HF solution or Pu(VII) in Li 5 PuO 6 ). In still other cases, an interplay of steric and redox effects can lead to interesting comparisons (e.g., instability of double fluoride salts of Pu(V) and Pu(VI) relative to U, Np, and Am analogues). Generalized ways to rationalize compounds containing actinides and lanthanides in unusual valences (particularly high valences), including the above and numerous other examples, will form the focus of this paper. Recently developed methods for synthesizing high valent f-element fluorides using superoxidizers and superacids at low temperatures will also be described. 65 refs., 8 figs., 9 tabs

Extraction chromatography of actinides

International Nuclear Information System (INIS)

Muller, W.

1978-01-01

Extraction chromatography of actinides in the oxidation state from 2 to 6 is reviewed. Data on using neutral (tbp), basic (substituted ammonium salts) and acidic [di-(2-ethylhexyl)-phosphoric acid (D2EHPA)] extracting agents ketones, esters, alcohols and β-diketones in this method are given. Using the example of actinide separation using D2EHPA, discussed are factors influencing the efficiency of their chromatography separation (nature and particle size of the carrier materials, extracting agents amount on the carrier, temperature and elution rate)

The Noah's Ark experiment: species dependent biodistributions of cationic 99mTc complexes

International Nuclear Information System (INIS)

Deutsch, Edward; Ketring, A.R.; Libson, Karen; Vanderheyden, J.-L.; Hirth, W.W.

1989-01-01

The time dependent biodistributions of three related 99m Tc complexes of 1, 2-bis(dimethylphosphino)ethane (DMPE) were evaluated in several animal species including humans: trans-[ 99m Tc v (DMPE) 2 O 2 ] + , trans-[ 99m Tc III (DMPE) 2 Cl 2 ] + and [ 99m Tc I (DMPE) 3 ] + . Imaging studies were performed in 10 animal species to evaluate these complexes as myocardial perfusion imaging agents. Animal models adequately predict the uninteresting behaviour of the Tc(V) cation in humans, predict to only a very limited extent the behaviour of the Tc(III) cation in humans and totally fail to predict the behaviour of the Tc(I) cation in humans. (U.K.)

Advanced Aqueous Separation Systems for Actinide Partitioning

Energy Technology Data Exchange (ETDEWEB)

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.

PREPARATION OF ACTINIDE-ALUMINUM ALLOYS

Science.gov (United States)

Moore, R.H.

1962-09-01

BS>A process is given for preparing alloys of aluminum with plutonium, uranium, and/or thorium by chlorinating actinide oxide dissolved in molten alkali metal chloride with hydrochloric acid, chlorine, and/or phosgene, adding aluminum metal, and passing air and/or water vapor through the mass. Actinide metal is formed and alloyed with the aluminum. After cooling to solidification, the alloy is separated from the salt. (AEC)

Actinide isotopes in the marine environment

International Nuclear Information System (INIS)

Holm, E.; Fukai, R.

1986-01-01

Studies of actinide isotopes in the environment are important not only from the viewpoint of their radiological effects on human life, but also from the fact that they act as excellent biochemical and geochemical tracers especially in the marine environment. For several of the actinide isotopes there is still a lack of basic data on concentration levels and further investigations on their chemical and physical speciation are required to understand their behaviour in the marine environment. The measured and estimated activity concentration levels of artificial actinides are at present in general a few orders of magnitude lower than those of the natural ones and their concentration factors in biota are relatively low, except in a few species of macroalgae and phytoplankton. The contribution from seafood to total ingestion of actinides by the world population is a few per cent and, therefore, the dose to man from these long-lived radionuclides caused by seafood ingestion is usually low. (orig.)

Incremental binding free energies of aluminum (III) vs. magnesium (II) complexes

International Nuclear Information System (INIS)

Mercero, Jose M.; Mujika, Jon I.; Matxain, Jon M.; Lopez, Xabier; Ugalde, Jesus M.

2003-01-01

A sequential ligand addition to the aluminum (III) cation has been studied using the B3LYP functional and a combined all-electron/pseudopotentials basis set. The aluminum complexes are compared with analogous magnesium (II) complexes. Different thermodynamical data, such as incremental binding energies, enthalpies, entropies and free energies, are presented for these addition reactions. While the magnesium (II) cation can only accommodate three negatively charged ligands, aluminum (III) accommodates four even after including bulk solvent effects. The main differences between both cations complexing with the neutral ligands, is that aluminum (III) is not able to form complexes with methanol until the number of methanol ligands is equal to 3. Magnesium (II) prefers to bind methanol and formamide when the number of ligands is small, while aluminum prefers formamide. For the largest complexes both cations prefer to bind water

Experimental studies and tests on An(III)/Ln(III) separation using the TODGA extractant

Energy Technology Data Exchange (ETDEWEB)

Heres, Xavier; Sorel, Christian; Miguirditchian, Manuel; Cames, Beatrice; Hill, Clement; Bisel, Isabelle; Espinoux, Denis; Viallesoubranne, Carole; Baron, Pascal; Lorrain, Brigitte [CEA/DEN/MAR/DRCP, Marcoule, BP17171, 30207 Bagnols/Ceze (France)

2009-06-15

Minor actinide recycling by separation and transmutation is worldwide considered as one of the most promising strategies to reduce the inventory of radioactive waste, thus contributing to make nuclear energy more sustainable. One of the different options investigated at the CEA Marcoule and within the ACSEPT project (a European collaborative project partly funded by the 7. EURATOM Framework Program) to separate trivalent minor actinide (Am(III)-Cf(III)) from the fission and activation products contained in PUREX raffinates is the TODGA process, which consists in: 1. Co-extracting trivalent 4f and 5f elements from highly acidic PUREX raffinates by a mixture of TODGA (tetraoctyl-diglycolamide) and TBP (tributyl-phosphate), dissolved in HTP (hydrogenated tetra-propene). 2. Selectively stripping the trivalent minor actinides by a hydrophilic poly-aminocarboxylic acid used as a complexing agent in a buffered aqueous solution, while the trivalent lanthanides are kept in the organic solvent thanks to a sodium nitrate salting-out effect. 3. Stripping the lanthanides in a diluted nitric acid solution. The major difficulty of this TODGA separation process is to tune the pH in a very narrow range of operating conditions in the second step, because of the high sensitivity of the performances of the flow-sheet vs pH. This difficulty was however overcome. This paper describes the development of the TODGA process from experimental studies to hot test implementation in shielded cells of the ATALANTE facility, including (i) the optimization of the extraction system (both the formulation of the organic solvent and those of the aqueous scrubbing and stripping solutions), (ii) the implementation of a cold test in small scale mixer-settlers in the G1 facility (MARCEL loop), using a surrogate feed composed of major fission products, (iii) the validation of some steps of the process, using a surrogate feed, spiked with Am-241 and Eu-152, and similar laboratory contactors (medium activity

Extraction of trivalent lanthanides and actinides by a synergistic mixture of thenoyltrifluoroacetone and a linear polyether

International Nuclear Information System (INIS)

Ensor, D.D.; Shah, A.H.

1984-01-01

Mixtures of a two component system, a linear polyether, 1,13-bis[8-quinolyl]-1,4,7,10,13-pentaoxatridecane, K-5, and thenoyltrifluoroacetone, HTTA, have been shown to exhibit synergistic character in the extraction of trivalent lanthanides and actinides. The effect of the addition of K-5 to the organic phase on the extractions of Ce(III), Eu(III), Tm(III), Am(III), Cm(III), Bk(III), and Cf(III) by HTTA in chloroform from 0.5M NaNO 3 at 25 0 C has been measured. These results indicate the extraction is enhanced by the formation of M(TTA) 3 K-5 adduct in the organic phase. The organic phase stability constants for the formation of these synergistic species have been calculated for all the metals studied. The magnitude of these organic phase stability constants for K-5 are similar to other common neutral donors. The order of stability does not follow the normal trend based on charge-to-radius ratio, but follows a pattern based on size, with Am(III) being the most stable

Actinide recycle in LMFBRs as a waste management alternative

International Nuclear Information System (INIS)

Beaman, S.L.

1979-01-01

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

Thin layers in actinide research

International Nuclear Information System (INIS)

Gouder, T.

1998-01-01

Surface science research at the ITU is focused on the synthesis and surface spectroscopy studies of thin films of actinides and actinide compounds. The surface spectroscopies used are X-ray and ultra violet photoelectron spectroscopy (XPS and UPS, respectively), and Auger electron spectroscopy (AES). Thin films of actinide elements and compounds are prepared by sputter deposition from elemental targets. Alloy films are deposited from corresponding alloy targets and could be used, in principle, as replicates of these targets. However, there are deviations between alloy film and target composition, which depend on the deposition conditions, such as pressure and target voltage. Mastering of these effects may allow us to study stoichiometric film replicates instead of thick bulk compounds. As an example, we discuss the composition of U-Ni films prepared from a UNi 5 target. (orig.)

Coprecipitation of the lanthanide and actinide elements with some carbonato and sulfato complexes

International Nuclear Information System (INIS)

Saito, A.; Morimoto, T.; Ueno, K.

1980-01-01

Coprecipitation of Eu(III), Th(IV), U(VI), Np(V), Am(III) and Cm(III) with carbonato and sulfato complexes of Nd(III), Th(IV) and U(VI) containing [Co(NH 3 ) 6 ] 3+ cation was investigated. Experiments were made using radioactive tracers. It is assumed that coprecipitation is mainly due to mixed crystal formation. The requirement for a large extent of coprecipitation is the similarity in ionic size, ionic charge and ionic species of the participating ions. In particular, Th(IV) sulfato complex carries tri- tetra- and hexavalent ions in quite high yields. (author)

Rapid determination of actinides in seawater samples

International Nuclear Information System (INIS)

Maxwell, S.L.; Culligan, B.K.; Hutchison, J.B.; Utsey, R.C.; McAlister, D.R.

2014-01-01

A new rapid method for the determination of actinides in seawater samples has been developed at the Savannah River National Laboratory. The actinides can be measured by alpha spectrometry or inductively-coupled plasma mass spectrometry. The new method employs novel pre-concentration steps to collect the actinide isotopes quickly from 80 L or more of seawater. Actinides are co-precipitated using an iron hydroxide co-precipitation step enhanced with Ti +3 reductant, followed by lanthanum fluoride co-precipitation. Stacked TEVA Resin and TRU Resin cartridges are used to rapidly separate Pu, U, and Np isotopes from seawater samples. TEVA Resin and DGA Resin were used to separate and measure Pu, Am and Cm isotopes in seawater volumes up to 80 L. This robust method is ideal for emergency seawater samples following a radiological incident. It can also be used, however, for the routine analysis of seawater samples for oceanographic studies to enhance efficiency and productivity. In contrast, many current methods to determine actinides in seawater can take 1-2 weeks and provide chemical yields of ∼30-60 %. This new sample preparation method can be performed in 4-8 h with tracer yields of ∼85-95 %. By employing a rapid, robust sample preparation method with high chemical yields, less seawater is needed to achieve lower or comparable detection limits for actinide isotopes with less time and effort. (author)

Investigation of the complexation and the migration of actinides and non-radioactive substances with humic acids under geogenic conditions. Complexation of humic acids with actinides in the ocidation state IV Th, U, Np

Energy Technology Data Exchange (ETDEWEB)

Sachs, S.; Schmeide, K.; Brendler, V.; Krepelova, A.; Mibus, J.; Geipel, G.; Heise, K.H.; Bernhard, G.

2004-03-01

Objective of this project was the study of basic interaction and migration processes of actinides in the environment in presence of humic acids (HA). To obtain more basic knowledge on these interaction processes synthetic HA with specific functional properties as well as {sup 14}C-labeled HA were synthesized and applied in comparison to the natural HA Aldrich. One focus of the work was on the synthesis of HA with distinct redox functionalities. The obtained synthetic products that are characterized by significantly higher Fe(III) redox capacities than Aldrich HA were applied to study the redox properties of HA and the redox stability of U(VI) humate complexes. It was confirmed that phenolic OH groups play an important role for the redox properties of HA. However, the results indicate that there are also other processes than the single oxidation of phenolic OH groups and/or other functional groups contributing to the redox behavior of HA. A first direct-spectroscopic proof for the reduction of U(VI) by synthetic HA with distinct redox functionality was obtained. The complexation behavior of synthetic and natural HA with actinides (Th, Np, Pu) was studied. Structural parameters of Pu(III), Th(IV), Np(IV) and Np(V) humates were determined by X-ray absorption spectroscopy (XAS). The results show that carboxylate groups dominate the interaction between HA and actinide ions. These are predominant monodentately bound. The influence of phenolic OH groups on the Np(V) complexation by HA was studied with modified HA (blocked phenolic OH groups). The blocking of phenolic OH groups induces a decrease of the number of maximal available complexing sites of HA, whereas complex stability constant and Np(V) near-neighbor surrounding are not affected. The effects of HA on the sorption and migration behavior of actinides was studied in batch and column experiments. Th(IV) sorption onto quartz and Np(V) sorption onto granite and its mineral constituents are affected by the pH value

Investigation of the complexation and the migration of actinides and non-radioactive substances with humic acids under geogenic conditions. Complexation of humic acids with actinides in the oxidation state IV Th, U, Np

International Nuclear Information System (INIS)

Sachs, S.; Schmeide, K.; Brendler, V.; Krepelova, A.; Mibus, J.; Geipel, G.; Heise, K.H.; Bernhard, G.

2004-03-01

Objective of this project was the study of basic interaction and migration processes of actinides in the environment in presence of humic acids (HA). To obtain more basic knowledge on these interaction processes synthetic HA with specific functional properties as well as 14 C-labeled HA were synthesized and applied in comparison to the natural HA Aldrich. One focus of the work was on the synthesis of HA with distinct redox functionalities. The obtained synthetic products that are characterized by significantly higher Fe(III) redox capacities than Aldrich HA were applied to study the redox properties of HA and the redox stability of U(VI) humate complexes. It was confirmed that phenolic OH groups play an important role for the redox properties of HA. However, the results indicate that there are also other processes than the single oxidation of phenolic OH groups and/or other functional groups contributing to the redox behavior of HA. A first direct-spectroscopic proof for the reduction of U(VI) by synthetic HA with distinct redox functionality was obtained. The complexation behavior of synthetic and natural HA with actinides (Th, Np, Pu) was studied. Structural parameters of Pu(III), Th(IV), Np(IV) and Np(V) humates were determined by X-ray absorption spectroscopy (XAS). The results show that carboxylate groups dominate the interaction between HA and actinide ions. These are predominant monodentately bound. The influence of phenolic OH groups on the Np(V) complexation by HA was studied with modified HA (blocked phenolic OH groups). The blocking of phenolic OH groups induces a decrease of the number of maximal available complexing sites of HA, whereas complex stability constant and Np(V) near-neighbor surrounding are not affected. The effects of HA on the sorption and migration behavior of actinides was studied in batch and column experiments. Th(IV) sorption onto quartz and Np(V) sorption onto granite and its mineral constituents are affected by the pH value and the

Radiochemistry and actinide chemistry

International Nuclear Information System (INIS)

Guillaumont, R.; Peneloux, A.

1989-01-01

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 10 12 , 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

Interaction between actinides and protein: the calmodulin

International Nuclear Information System (INIS)

Brulfert, Florian

2016-01-01

Considering the environmental impact of the Fukushima nuclear accident, it is fundamental to study the mechanisms governing the effects of the released radionuclides on the biosphere and thus identify the molecular processes generating the transport and deposition of actinides, such as neptunium and uranium. However, the information about the microscopic aspect of the interaction between actinides and biological molecules (peptides, proteins...) is scarce. The data being mostly reported from a physiological point of view, the structure of the coordination sites remains largely unknown. These microscopic data are indeed essential for the understanding of the interdependency between structural aspect, function and affinity.The Calmodulin (CaM) (abbreviation for Calcium-Modulated protein), also known for its affinity towards actinides, acts as a metabolic regulator of calcium. This protein is a Ca carrier, which is present ubiquitously in the human body, may also bind other metals such as actinides. Thus, in case of a contamination, actinides that bind to CaM could avoid the protein to perform properly and lead to repercussions on a large range of vital functions.The complexation of Np and U was studied by EXAFS spectroscopy which showed that actinides were incorporated in a calcium coordination site. Once the thermodynamical and structural aspects studied, the impact of the coordination site distortion on the biological efficiency was analyzed. In order to evaluate these consequences, a calorimetric method based on enzyme kinetics was developed. This experiment, which was conducted with both uranium (50 - 500 nM) and neptunium (30 - 250 nM) showed a decrease of the heat produced by the enzymatic reaction with an increasing concentration of actinides in the medium. Our findings showed that the Calmodulin actinide complex works as an enzymatic inhibitor. Furthermore, at higher neptunium (250 nM) and uranium (500 nM) concentration the metals seem to have a poison

Managing Zirconium Chemistry and Phase Compatibility in Combined Process Separations for Minor Actinide Partitioning

Energy Technology Data Exchange (ETDEWEB)

Wall, Nathalie [Washington State Univ., Pullman, WA (United States); Nash, Ken [Washington State Univ., Pullman, WA (United States); Martin, Leigh [Washington State Univ., Pullman, WA (United States)

2017-03-17

In response to the NEUP Program Supporting Fuel Cycle R&D Separations and Waste Forms call DEFOA- 0000799, this report describes the results of an R&D project focusing on streamlining separation processes for advanced fuel cycles. An example of such a process relevant to the U.S. DOE FCR&D program would be one combining the functions of the TRUEX process for partitioning of lanthanides and minor actinides from PUREX(UREX) raffinates with that of the TALSPEAK process for separating transplutonium actinides from fission product lanthanides. A fully-developed PUREX(UREX)/TRUEX/TALSPEAK suite would generate actinides as product(s) for reuse (or transmutation) and fission products as waste. As standalone, consecutive unit-operations, TRUEX and TALSPEAK employ different extractant solutions (solvating (CMPO, octyl(phenyl)-N,Ndiisobutylcarbamoylmethylphosphine oxide) vs. cation exchanging (HDEHP, di-2(ethyl)hexylphosphoric acid) extractants), and distinct aqueous phases (2-4 M HNO₃ vs. concentrated pH 3.5 carboxylic acid buffers containing actinide selective chelating agents). The separate processes may also operate with different phase transfer kinetic constraints. Experience teaches (and it has been demonstrated at the lab scale) that, with proper control, multiple process separation systems can operate successfully. However, it is also recognized that considerable economies of scale could be achieved if multiple operations could be merged into a single process based on a combined extractant solvent. The task of accountability of nuclear materials through the process(es) also becomes more robust with fewer steps, providing that the processes can be accurately modeled. Work is underway in the U.S. and Europe on developing several new options for combined processes (TRUSPEAK, ALSEP, SANEX, GANEX, ExAm are examples). There are unique challenges associated with the operation of such processes, some relating to organic phase chemistry, others arising from the

On the hazard accumulation of actinide waste in a Pu-fueled LMFBR power economy with and without by-product actinide recycling

International Nuclear Information System (INIS)

Anselmi, L.; Caruso, K.; Hage, W.; Schmidt, E.

1979-01-01

The actinide waste arisings in terms of hazard potential for ingestion and inhalation are given for a Pu-fueled LMFBR Power Economy as function of decay time. The data were assessed for two simplified fuel cycles, one considering the recycling of by-product actinides and the other their complete discharge to the high-level waste. Two durations of nuclear power and several loss fractions of actinides to the waste were considered. The major contributors in form of chemical elements or isotopes to the actinide waste hazard built up during the nuclear power duration were identified for various decay intervals

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

International Nuclear Information System (INIS)

Adnet, J.M.

1991-07-01

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

Chemical Interaction between U(VI) and Eu(III) ions on a Silica Surface

International Nuclear Information System (INIS)

Park, K. K.; Cha, W. S.; Cho, H. R.; Im, H. J.; Jung, E. C.

2010-01-01

Understanding the chemical behavior of actinide in groundwater flow is important for assessing the possibility of its migration with water flow in the radioactive waste disposal site. Precipitation/ dissolution in groundwater and adsorption/desorption onto a geological solid surface would determine its migration. The sorption in a geochemical system was expected to be a reaction on a naturally equilibrated surface. However, the construction of a waste disposal facility could disturb this equilibrium state, induce a new reaction environment and affect a nanoscopic surface reaction of actinide. Uranium is ubiquitous in the natural environment and a representative element in a nuclear fuel cycle and in a high level radioactive waste. In oxic environments, it is typically present as uranyl oxocation (UO 2 2+ ), which is easily adsorbed and thereby removed from a solution in the near neutral pH range. This adsorption would form a new surface condition to give an unexpected adsorption behavior for other actinide ions. Eu(III) frequently is used as a chemical analogue of Am(III) and Cm(III) in migration chemistry. The adsorption phenomena has been interpreted with the help of a SCM(surface complexation model). Some spectroscopic techniques such as EPR (Electron Paramagnetic Resonance), IR (InfraRed), EXAFS (Extended X-ray Absorption Fine Structure) and TRLFS (Time Resolved Laser Fluorescence Spectroscopy) have been used for the identification of a modeled adsorbing species. In the case of fluorescence elements, TRLFS has advantages over other techniques for its high sensitivity being proportional to laser source intensity and good selectivity depending on specific transition and lifetime. This technique can be applied to a species on a solid surface not absorbing light such as silica. U(VI) and Eu(III) have fluorescente properties reflecting their coordination structure. In this study, the interaction between U(VI) and Eu(III) on a silica surface was studied by a

Calculated investigation of actinide transmutation in the BOR-60 reactor

International Nuclear Information System (INIS)

Zhemkov, I.Yu.; Ishunina, O.V.; Yakovleva, I.V.

2000-01-01

One of the prospective actinide burner reactor type is the fast reactor with a 'hard' spectrum and small breeding factor, which is the BOR-60. The calculated investigations demonstrate that Loading up to 40% of minor-actinides to the BOR-60 reactor did not lead to the considerable change of neutron-physical characteristics. The performed calculations show that the BOR- 60 reactor possesses a high efficiency of the minor-actinide and plutonium bum-up (up to 37 kg/(TW · h)) hat is comparable with properties of the actinide burner-reactors under design. The BOR-60 reactor can provide a homogeneous minor-actinide Loading (minor-actinide addition to the standard fuel) to the core and heterogeneous Loading (as separate assemblies-targets with a high minor-actinide fraction) to the first rows of a radial blanket that allows the optimum usage of the reactor and its characteristics. (authors)

Autoradiographic study of actinide sorption on climax stock granite

International Nuclear Information System (INIS)

Beall, G.W.; O'Kelley, G.D.; Allard, B.

1980-06-01

An autoradiographic technique that employed an arrangement for placing in firm contact Polaroid sheet film, a scintillator screen, and the radioactive face of a specimen was applied to a study of the sorption of americium, neptunium, plutonium, and uranium on Climax Stock granite under varying conditions of pH and Eh. Qualitative agreement was found between the sorption of americium on crushed, pure minerals and on the minerals comprising the specimen of Climax Stock granite. The observations also supported a mechanism for reduction of Np(V) to Np(IV) and Pu(VI) to Pu(IV) by Fe(II)-containing minerals. There was no evidence for reduction of U(VI) by the Fe(II)-containing minerals, although the uranium, assumed to be present as UO 2 2+ , appeared to be the only actinide species to exhibit sorption by a simple, cation-exchange mechanism at particular mineral sites. Some implications of these results for nuclear waste isolation are discussed briefly

Interaction of trivalent lanthanides and actinides with aluminium oxides and hydroxides; Wechselwirkung von dreiwertigen Lanthaniden und Actiniden mit Aluminiumoxiden und -hydroxiden

Energy Technology Data Exchange (ETDEWEB)

Kupcik, Tomas

2011-10-28

The subject of the present work is the interaction of trivalent actinides Cm(III) and lanthanides (Eu(III) and Gd(III)) with aluminium oxides and -hydroxides, namely corundum/sapphire (α-Al{sub 2}O{sub 3}), gibbsite (α-Al(OH){sub 3}) and bayerite (β-Al(OH){sub 3}), as well as the polyoxocations ''Al{sub 13}'' (Al{sub 13}O{sub 4}(OH){sub 24}(H{sub 2}O){sub 12}{sup 7+}) and ''GaAl{sub 12}'' (GaO{sub 4}Al{sub 12}(OH){sub 24}(H{sub 2}O){sub 12}{sup 7+}). These investigations should contribute to a sound understanding of the solution-mineral-interface reactions relevant for the migration of radionuclides (in particular the actinides) in the near and far field of a repository for high-level radioactive waste in deep geological formations, e.g. adsorption and structural incorporation. Batch sorption studies show similar logK{sub d} values for Eu(III) sorption onto corundum and bayerite at low metal ion concentrations ([M(III)] ∝ 7.10{sup -7} M). These similarities can be related to the formation of Al-OH groups on the aluminium oxide surfaces. Comparable logK{sub d} values could be found in earlier investigations for Gd(III) sorbed onto γ-Al{sub 2}O{sub 3}. In agreement with the batch sorption results at trace metal ion concentrations, time resolved laser fluorescence spectroscopy (TRLFS) studies on the interaction of Cm(III) with corundum and bayerite suggest a similar Cm(III) speciation between pH = 3 and 13. Three different surface sorbed Cm(III) species can be distinguished for these mineral phases ([surface..Cm(OH){sub x}(H{sub 2}O){sub 5-x}]{sup 3-x} with x = 0, 1, 2). Comparable TRLFS results can also be found for Cm(III) sorbed on the sapphire (001) single crystal surface and on ''Al{sub 13}'' and ''GaAl{sub 12}''. In the Cm(III)/gibbsite system, spectroscopic results show clear differences in comparison to bayerite, corundum and γ-Al{sub 2}O{sub 3}, e.g. a Cm(III) species of

Solubility Determination of Uranium (IV) Oxalates U(C{sub 2}O{sub 4}){sub 2}.6H{sub 2}O and M{sub 2}U{sub 2}(C{sub 2}O{sub 4}){sub 5}.nH{sub 2}O (M = mono-charged cation)

Energy Technology Data Exchange (ETDEWEB)

Costenoble, Sylvain; Grandjean, Stephane; Arab-Chapelet, Benedicte [CEA, Nuclear Energy Division, Radiochemistry and Process Department, Actinide Chemistry Laboratory, CEA Marcoule, bat 399, BP17171, 30207 Bagnols sur Ceze cedex (France); Abraham, Francis [UCCS - Solid Chemistry Unit, UMR CNRS 8181, ENSCL-USTL, B.P. 108, 59652 Villeneuve d' Ascq cedex (France)

2008-07-01

The solubility of uranium (IV) oxalate compounds was studied in order to have a precise insight of the behaviour of An(IV)-An(III) (An(IV) = U, Np or Pu and An(III) = Pu or Am) mixed oxalate in the context of oxalic co-conversion for actinide co-management. Concepts of thermodynamics of aqueous-solid solution are reviewed by introducing LIPPMANN theory and THORSTENSON and PLUMMER 'stoichiometric saturation' model in a way to understand and model the system of interest. Different analytical techniques have been developed in order to titrate uranium and/or other actinides at trace levels in solution. This thorough investigation is the basis of further experiments on the solubility of mixed U(IV)- An(III) oxalate solid solutions as a function of the nature of the trivalent actinide and the An(III)/U(IV) ratio. (authors)

Actinide removal from aqueous solution with activated magnetite

International Nuclear Information System (INIS)

Kochen, R.L.; Thomas, R.L.

1987-01-01

An actinide aqueous waste treatment process using activated magnetite has been developed at Rocky Flats. The use and effectiveness of various magnetites in lowering actinide concentrations in aqueous solution are described. Experiments indicate that magnetite particle size and pretreatment (activation of the magnetite surface with hydroxyl ions greatly influence the effective use of magnetite as an actinide adsorbent. With respect to actinide removal, Ba(OH) 2 -activated magnetite was more effective over a broader pH range than was NaOH-activated magnetite. About 50% less Ba(OH) 2 -activated magnetite was required to lower plutonium concentration from 10 -4 to 10 -8 g/l. 7 refs., 8 tabs

Formation of actinides in irradiated HTGR fuel elements

Energy Technology Data Exchange (ETDEWEB)

dos Santos, A. M.

1976-03-15

Actinide nuclide concentrations of 11 spent AVR fuel elements were determined experimentally. The burnup of the spheres varied in the range between 10% and 100% fifa, the Th : U ratio was 5 : 1. The separation procedures for an actinide isolation were tested with highly irradiated ThO/sub 2/. Separation and decontamination factors are presented. Build-up of /sup 232/U was discussed. The AVR breeding rate was ascertained to be 0.5. The hazard potential of high activity waste was calculated. Actinide recovery factors were proposed in order to reduce the hazard potential of the waste by an actinide removal under consideration of the reprocessing technology which is available presently.

Ground-state electronic structure of actinide monocarbides and mononitrides

DEFF Research Database (Denmark)

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 increa...

Organometallic neptunium(III) complexes.

Science.gov (United States)

Dutkiewicz, Michał S; Farnaby, Joy H; Apostolidis, Christos; Colineau, Eric; Walter, Olaf; Magnani, Nicola; Gardiner, Michael G; Love, Jason B; Kaltsoyannis, Nikolas; Caciuffo, Roberto; Arnold, Polly L

2016-08-01

Studies of transuranic organometallic complexes provide a particularly valuable insight into covalent contributions to the metal-ligand bonding, in which the subtle differences between the transuranium actinide ions and their lighter lanthanide counterparts are of fundamental importance for the effective remediation of nuclear waste. Unlike the organometallic chemistry of uranium, which has focused strongly on U(III) and has seen some spectacular advances, that of the transuranics is significantly technically more challenging and has remained dormant. In the case of neptunium, it is limited mainly to Np(IV). Here we report the synthesis of three new Np(III) organometallic compounds and the characterization of their molecular and electronic structures. These studies suggest that Np(III) complexes could act as single-molecule magnets, and that the lower oxidation state of Np(II) is chemically accessible. In comparison with lanthanide analogues, significant d- and f-electron contributions to key Np(III) orbitals are observed, which shows that fundamental neptunium organometallic chemistry can provide new insights into the behaviour of f-elements.

Creation, synthesis and characterisation of nitrogenous poly-heterocyclic new molecules for specific complexation of metallic cations

International Nuclear Information System (INIS)

Dupont, C.

2010-01-01

In France, the nuclear waste issued from the industrial reprocessing of spent nuclear fuels (by the PUREX process) are currently vitrified at the La Hague plant, waiting for a final disposal in a deep geological repository. The law voted in June 2006 on the management of highly active nuclear waste plans to look for solutions enabling the separation and transmutation of long-lived radionuclides so as to reduce the quantity and noxiousness of the final nuclear waste. To address this issue, the CEA investigates and elaborates advanced separation processes based on specially designed complexing or extracting molecules to selectively extract minor actinides from PUREX raffinates containing fission products like lanthanides, which are neutron scavengers. BTP or bis-triazinyl-pyridines have been extensively studied at the CEA (and in Europe) for actinides(III)/lanthanides(III) separation. They complex actinides(III) selectively. However, they are sensitive to degradation by hydrolysis and radiolysis. Besides, their separation mechanisms are not well understood, especially the influence of their substituting groups on their complexing and extracting properties. The first part of work reports the syntheses of various BTP and BTBP molecules, differently substituted, as well as a new family of poly-aromatic nitrogen-contained ligands: BPBT, presenting a pyridine/triazine sequence that has never been reported in the literature. The second part is devoted to the physico-chemistry studies of the synthesized molecules, such as the determination of their protonation and complexation constants to describe the influence of different substituting groups. Finally, the last part outlines solvent extraction studies by using these ligands either like extractants or like complexants. (author) [fr

Experimental studies of actinides in molten salts

Energy Technology Data Exchange (ETDEWEB)

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.

Neutron nuclear data evaluation for actinide nucleic

International Nuclear Information System (INIS)

Chen Guochang; Yu Baosheng; Duan Junfeng; Ge Zhigang; Cao Wentian; Tang Guoyou; Shi Zhaomin; Zou Yubin

2010-01-01

The nuclear data with high accuracy for minor actinides are playing an important role in nuclear technology applications, including reactor design and operation, fuel cycle concepts, estimation of the amount of minor actinides in high burn-up reactors and the minor actinides transmutation. Through describe the class of nuclear data and nuclear date library, and introduce the procedure of neutron nuclear data evaluation. 234 U(n, f) and 237 Np(n, 2n) reaction experimental data evaluation was evaluated. The fission nuclear data are updated and improved. (authors)

Experimental studies of actinides in molten salts

International Nuclear Information System (INIS)

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

Interactions of Microbes found at Aespoe Underground Lab with Actinides such as Curium, Plutonium and Uranium

Energy Technology Data Exchange (ETDEWEB)

Moll, H.; Merroun, M.; Geipel, G.; Rossberg, A.; Hennig, C.; Selenska-Pobell , S.; Bernhard, G. [Forschungszentrum Dresden-Rossendorf e.V., Inst. fuer Radioc hemie, 01314 Dresden (Germany)]. e-mail: h.moll@fzd.de; Stumpf, Th. [Forschungszentru m Karlsruhe, Inst. fuer Nukleare Entsorgung, 76021 Karlsruhe (Germany)

2007-06-15

Sulfate-reducing bacteria (SRB) frequently occur in the deep granitic rock aquifers at the Aespoe Hard Rock Laboratory (Aespoe HRL), Sweden. The new SRB strain Desulfovibrio aespoeensis could be isolated. Results describing the basic interaction mechanisms of uranium, curium, and plutonium with cells of D. aespoeensis DSM 10631T will be presented. The interaction experiments with the actinides showed that the cells are able to remove all three actinides from the surrounding solution. The amount of removed actinide and the interaction mechanism varied among the different actinides. The main U(VI) removal occurred after the first 24 h. The contact time, pH and [U(VI)]initial influence the U removal efficiency. The presence of uranium caused a damaging of the cell membranes. TEM revealed an accumulation of U inside the bacterial cell. D. aespoeensis are able to form U(IV). A complex interaction mechanism takes place consisting of biosorption, bioreduction and bioaccumulation. In the case of {sup 242}Pu, solvent extractions, UV-vis- and XANES spectroscopy were used to determine the speciation of the Pu oxidation states. In the first step, the Pu(VI) and Pu(IV)-polymers are bound to the biomass. Solvent extractions showed that 97 % of the initially present Pu(VI) is reduced to Pu(V) due to the activity of the cells within the first 24 h. Most of the formed Pu(V) dissolves from the cell envelope back to the aqueous solution due to the weak complexing properties of this plutonium oxidation state. In the case of curium at a much lower metal concentration of 3x10{sup -7} M, a pure biosorption of Cm(III) on the cell envelope forming an inner-sphere surface complex most likely with organic phosphate groups was detected. To summarize, the strength of the interaction of D. aespoeensis with the selected actinides at pH 5 and actinide concentrations = 10 mg/L ([Cm] 0.07 mg/L) follows the pattern: Cm > U > Pu >> Np.

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

International Nuclear Information System (INIS)

Beaman, S.L.; Aitken, E.A.

1976-01-01

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

Multi-podant diglycolamides and room temperature ionic liquid impregnated resins: An excellent combination for extraction chromatography of actinides.

Science.gov (United States)

Gujar, R B; Ansari, S A; Verboom, W; Mohapatra, P K

2016-05-27

Extraction chromatography resins, prepared by impregnating two multi-podant diglycolamide ligands, viz. diglycolamide-functionalized calix[4]arene (C4DGA) and tripodal diglycolamide (T-DGA) dissolved in the room temperature ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide (RTIL: C4mimTf2N) on Chromosorb-W (an inert solid support), gave excellent results for the removal of trivalent actinides from acidic waste solutions. Distribution coefficient measurements on several metal ions showed selective sorption of Am(III) over hexavalent uranyl ions and other fission product elements such as strontium and cesium. The sorbed metal ions could be efficiently desorbed with a complexing solution containing guanidine carbonate and EDTA buffer. The sorption of Am(III) on both resins followed pseudo-second order rate kinetics with rate constants of 1.37×10(-6) and 6.88×10(-7)g/cpmmin for T-DGA and C4DGA resins, respectively. The metal sorption on both resins indicated the Langmuir monolayer chemisorption phenomenon with Eu(III) sorption capacities of 4.83±0.21 and 0.52±0.05mg per g of T-DGA and C4DGA resins, respectively. The results of column studies show that these resins are of interest for a possible application for the recovery of hazardous trivalent actinides from dilute aqueous solutions. Copyright © 2016 Elsevier B.V. All rights reserved.

Synthesis of zirconia sol stabilized by trivalent cations (yttrium and neodymium or americium): a precursor for Am-bearing cubic stabilized zirconia.

Science.gov (United States)

Lemonnier, Stephane; Grandjean, Stephane; Robisson, Anne-Charlotte; Jolivet, Jean-Pierre

2010-03-07

Recent concepts for nuclear fuel and targets for transmuting long-lived radionuclides (minor actinides) and for the development of innovative Gen-IV nuclear fuel cycles imply fabricating host phases for actinide or mixed actinide compounds. Cubic stabilized zirconia (Zr, Y, Am)O(2-x) is one of the mixed phases tested in transmutation experiments. Wet chemical routes as an alternative to the powder metallurgy are being investigated to obtain the required phases while minimizing the handling of contaminating radioactive powder. Hydrolysis of zirconium, neodymium (a typical surrogate for americium) and yttrium in aqueous media in the presence of acetylacetone was firstly investigated. Progressive hydrolysis of zirconium acetylacetonate and sorption of trivalent cations and acacH on the zirconia particles led to a stable dispersion of nanoparticles (5-7 nm) in the 6-7 pH range. This sol gels with time or with temperature. The application to americium-containing solutions was then successfully tested: a stable sol was synthesized, characterized and used to prepare cubic stabilized zirconia (Zr, Y, Am)O(2-x).

Band structure studies of actinide systems

International Nuclear Information System (INIS)

Koelling, D.D.

1976-01-01

The nature of the f-orbitals in an actinide system plays a crucial role in determining the electronic properties. It has long been realized that when the actinide separation is small enough for the f-orbitals to interact directly, the system will exhibit itinerant electron properties: an absence of local moment due to the f-orbitals and sometimes even superconductivity. However, a number of systems with the larger actinide separation that should imply local moment behavior also exhibit intinerant properties. Such systems (URh 3 , UIr 3 , UGe 3 , UC) were examined to learn something about the other f-interactions. A preliminary observation made is that there is apparently a very large and ansiotropic mass enhancement in these systems. There is very good reason to believe that this is not solely due to large electron--electron correlations but to a large electron--phonon interaction as well. These features of the ''non-magnetic'', large actinide separation systems are discussed in light of our results to date. Finally, the results of some recent molecular calculations on actinide hexafluorides are used to illustrate the shielding effects on the intra-atomic Coulomb term U/sub f-f/ which would appear in any attempt to study the formation of local moments. As one becomes interested in materials for which a band structure is no longer an adequate model, this screened U/sub ff/ is the significant parameter and efforts must be made to evaluate it in solid state systems

Properties of minor actinide nitrides

International Nuclear Information System (INIS)

Takano, Masahide; Itoh, Akinori; Akabori, Mitsuo; Arai, Yasuo; Minato, Kazuo

2004-01-01

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)

Behaviour of trivalent actinides and lanthanide elements in chloride solution; Comportement des lanthanides et transuraniens trivalents en milieu chlorhydrique

Energy Technology Data Exchange (ETDEWEB)

Marin, B [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1969-07-01

The aim of this work is to compare the complexation in chloride solutions of trivalent lanthanides and actinides. We have first studied the solvatation of these cations without complexation. We found a difference between Am, Cm and Rare Earths (we can separate lanthanides into Light and Heavy Rare Earths). For studying the complexation we choose the technic of electrophoresis on paper after establishing a simple theory of mobilities in complex solutions. The hydrolysis of these cations was studied and compared in chloride solutions. We have then studied the complexation with the Cl{sup -} ligand in some solutions: HCl, NH{sub 4}Cl, CaCl{sub 2}, CeCl{sub 3}, LiCl. We have established that the complexation is the same in dilute HCl solutions but in concentrated solutions the trivalent actinides are more complexed. This difference is sharper in LiCl solutions. We also proposed the different models of complex in these solutions. (author) [French] Le but de ce travail est de comparer les transuraniens et lanthanides trivalents au point de vue de leur complexation en solution chlorhydrique. Nous avons ete amenes tout d'abord a etudier la solvatation de ces cations non complexes. C'est ainsi que nous pouvons constater une difference entre Am, Cm et les lanthanides. Ces derniers pouvant se separer en lanthanides legers et lanthanides lourds. Pour etudier la complexation nous avons utilise l'electrophorese sur papier apres avoir donne une theorie simple des mobilites en milieu complexant. Apres avoir etudie et compare l'hydrolyse de ces divers cations en solution chlorhydrique, nous avons etudie leur complexation avec l'ion Cl{sup -} dans dans divers milieux: HCl, NH{sub 4}Cl, CaCl{sub 2}, CeCl{sub 3}, LiCl. ous avons note qu'en solution HCl les deux series se comportent de la meme facon pour des concentrations faibles en Cl{sup -} mais que les transuraniens se complexent plus fortement dans les solutions concentrees. Cette difference s'accroit encore dans les milieux

ALMR potential for actinide consumption

International Nuclear Information System (INIS)

Cockey, C.L.; Thompson, M.L.

1992-01-01

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)

Purification of Anthocyanins with o-Dihydroxy Arrangement by Sorption in Cationic Resins Charged with Fe(III

Directory of Open Access Journals (Sweden)

Araceli Castañeda-Ovando

2014-01-01

Full Text Available In the present work, a new purification method of anthocyanins with o-dihydroxy arrangement is proposed. This method is based on a ligand-exchange mechanism, using a cationic exchange resin loaded with metallic ions in order to increase the affinity of the resin to the anthocyanin(s with o-dihydroxy arrangement. This method was used to purify the main anthocyanin (cyanidin-3-glucoside; Cy-3-glc from the anthocyanic methanolic extract of blue corn. The best sorption result was using Fe(III in its ion form. The purification procedure begins with the formation of a metal-anthocyanin complex (Cy-3-glc-Fe which was optimal at pH 5, followed by a NaOH 0.1 M elution process in order to eliminate anthocyanins without o-dihydroxy arrangement, sugars, and organic acids. Finally, the pure anthocyanin is obtained by adding HCl 0.1 M which breaks the metal-anthocyanin complex.

Actinide recycle potential in the integral fast reactor

International Nuclear Information System (INIS)

Chang, Y.I.

1993-01-01

The Integral Fast Reactor (IFR) fuel cycle holds promise for substantial improvements in economics, diversion-resistance, and waste management. In the IFR pyroprocessing, minor actinides accompany plutonium product stream, and therefore, actinide recycle occurs naturally. The fast neutron spectrum of the IFR makes it an ideal actinide burner, as well. This paper discusses technical features of the IFR fuel cycle, its technical progress, the development status, and potential implications on long-term waste management

TRLIFS study of Eu(III) spectroscopic properties to obtain structural and thermodynamic informations on lanthanide-malonamide complexes in the Eu(III)/NaNO3/tetraethylmalonamide system

International Nuclear Information System (INIS)

Couston, L.; Charbonnel, M.C.; Flandin, J.L.; Rancier, F.; Moulin, C.

2004-01-01

Improvement of the nuclear fuel reprocessing involves separating the minor actinides (Am(III) and Cm(III)) from the fission products. In the French strategy, the first step consists in the separation of the trivalent actinides and lanthanides from high-level liquid waste, for which malonamides RR'NCO(CHR '' )CONRR' are promising ligands. These molecules have been optimized for reprocessing but still require basic chemical studies to describe the complexation mechanisms at a molecular scale. This paper discusses a thermodynamic and structural study of a Ln(III)-malonamide complex formed with the hydrosoluble tetraethylmalonamide ligand (TEMA = (C 2 H 5 ) 2 NCOCH 2 CON(C 2 H 5 ) 2 ) dissolved in a nitrate medium. Despite the simplified chemical system obtained with TEMA, its weak chemical affinity and its physical properties pushed the analytical techniques to their limits. The sensitivity of time-resolved laser-induced fluorescence spectroscopy (TRLIFS) combined with the major luminescent spectroscopic properties of Eu(III) (hypersensitive band and fluorescence lifetime) were successfully used to determine the equilibrium constant and hydration number in the Eu(III), TEMA, and NO 3 - system. Fluorescence lifetimes, connected with the first coordination sphere of the solvated metal, clearly show the inner-sphere location of nitrate in the Eu(NO 3 ) 2+ complex, the outer-sphere location of TEMA in the Eu(TEMA) 3+ complex, and the outer-sphere location of both ligands in the Eu(NO 3 )(TEMA) 2+ complex. (orig.)

A review of modelling the interaction between natural organic matter and metal cations

International Nuclear Information System (INIS)

Falck, W.E.

1989-01-01

This report reviews techniques available to model the interaction between natural organic matter (mainly fulvic and humic acids) and protons and metal cations. A concise definition of natural organic matter is given and their properties are outlined. These materials are macromolecules which exhibit a polyelectrolyte character owing to numerous dissociable functional groups which are attached to their carbon backbone or from integral parts of the structure. The polyelectrolyte character is thought to be responsible for their conformation, hydrogen bonding or bridging by metal cations between subunits being important mechanisms. Environmental parameters like pH and ionic strength thus will have profound effects on the conformation of natural organic matter, the properties of which can change from being a flexible polymer to being a rigid gel. Binding mechanisms and binding strengh are discussed and an overview of relevant techniques of investigation is given. This work is part of the Commission's Mirage project - Phase 2, research area Geochemistry of actinides and fission products in natural aquifer systems

The radiological impact of actinides discharged to the Irish Sea

International Nuclear Information System (INIS)

Hunt, G.J.; Smith, B.D.

1999-01-01

This paper describes the radiological effects of releases of actinides to the Irish Sea from Sellafield, the major source. Exposure pathways to man since the commencement of discharges in 1952 are reviewed; the importance of actinides began to increase with increased discharges in the 1970s. With the demise of the porphyra/laverbread pathway due to transport difficulties, the pathway due to fish and shellfish consumption became critical, particularly for actinides through molluscan shellfish. A reassessment on the current basis of effective dose shows that peak exposures to the critical group of about 2 mSv yr -1 were received in the mid-1970s, about 30% of which was due to actinides. Effective doses have since reduced but the relative importance of actinides is greater, due to the interplay of discharges of radionuclides from Sellafield and their behaviour in the environment. Additive doses through sea food due to releases of natural radionuclides from the Marchon phosphate plant at Whitehaven are also considered, although the actinide component from this source has been small. Exposures due to actinides from Sellafield via other pathways are shown to be much lower than those involving sea food. Collective doses are also considered; these peaked at about 300 man-Sv to the European population (including the UK) in 1979, with only a few percent due to actinides. As in the case of critical group doses, the relative importance of actinides has increased in recent years within the decreasing total collective dose. For both critical group and collective doses, therefore, the actinide component needs to be kept under review. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

Environmental chemistry of the actinide elements

International Nuclear Information System (INIS)

Rao Linfeng

1986-01-01

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

Actinide separations by supported liquid membranes

International Nuclear Information System (INIS)

Danesi, P.R.; Horwitz, E.P.; Rickert, P.; Chiarizia, R.

1984-01-01

The work has demonstrated that actinide removal from synthetic waste solutions using both flat-sheet and hollow-fiber SLM's is a feasible chemical process at the laboratory scale level. The process is characterized by the typical features of SLM's processes: very small quantities of extractant required; the potential for operations with high feed/strip volume ratios, resulting in a corresponding concentration factor of the actinides; and simplicity of operation. Major obstacles to the implementation of the SLM technology to the decontamination of liquid nuclear wastes are the probable low resistance of polypropylene supports to high radiation fields, which may prevent the application to high-level nuclear wastes; the unknown lifetime of the SLM; and the high Na content of the separated actinide solution

Analysis of large soil samples for actinides

Science.gov (United States)

Maxwell, III; Sherrod, L [Aiken, SC

2009-03-24

A method of analyzing relatively large soil samples for actinides by employing a separation process that includes cerium fluoride precipitation for removing the soil matrix and precipitates plutonium, americium, and curium with cerium and hydrofluoric acid followed by separating these actinides using chromatography cartridges.

Cation exchange process for recovery of plutonium from laboratory solutions containing chloride

International Nuclear Information System (INIS)

Gray, L.W.

1978-10-01

A cation exchange technique was developed for the separation of plutonium from laboratory solutions containing either Pu(III) or Pu(III)--Pu(IV) mixtures in acidic solutions containing chloride ions. The procedure consists of adjusting the acid concentration to less than one molar and adjusting the valence of the plutonium ion to the (III) state, if necessary. The adjusted solution is fed to a cation exchange column and washed with distilled water to remove residual chlorides from the column. Plutonium is then eluted from the column with 5M nitric acid containing 0.34M sulfamic acid. This procedure was used to separate plutonium from 1.2M chloride solution on a production-scale column. Typical plutonium recovery was 99.97%, while greater than 96% of the original chloride was rejected

Spin and orbital moments in actinide compounds

DEFF Research Database (Denmark)

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

1991-01-01

The extended spatial distribution of both the transition-metal 3d electrons and the actinide 5f electrons results in a strong interaction between these electron states when the relevant elements are alloyed. A particular interesting feature of this hybridization, which is predicted by single...... 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...

Evaluating the efficacy of a minor actinide burner

International Nuclear Information System (INIS)

Dobbin, K.D.; Kessler, S.F.; Nelson, J.V.; Omberg, R.P.; Wootan, D.W.

1993-06-01

The efficacy of a minor actinide burner can be evaluated by comparing safety and economic parameters to the support ratio. Minor actinide mass produced per unit time in this number of Light Water Reactors (LWRs) can be burned during the same time period in one burner system. The larger the support ratio for a given set of safety and economic parameters, the better. To illustrate this concept, the support ratio for selected Liquid Metal Reactor (LMR) burner core designs was compared with corresponding coolant void worths, a fundamental safety concern following the Chernobyl accident. Results can be used to evaluate the cost in reduced burning of minor actinides caused by LMR sodium void reduction efforts or to compare with other minor actinide burner systems

Production and measurement of minor actinides in the commercial fuel cycle

International Nuclear Information System (INIS)

Stanbro, W.D.

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

Trends in actinide processing at Hanford

International Nuclear Information System (INIS)

Harmon, H.D.

1993-09-01

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

Subcritical limits for special fissile actinides

International Nuclear Information System (INIS)

Clark, H.K.

1980-01-01

Critical masses and subcritical mass limits in oxide-water mixtures were calculated for actinide nuclides other than /sup 233/U, /sup 235/U, and /sup 239/Pu that have an odd number of neutrons in the nucleus; S/sub n/ transport theory was used together with cross sections, drawn from the GLASS multigroup library, developed to provide accurate forecasts of actinide production at Savannah River

Transmutation of actinides in power reactors.

Science.gov (United States)

Bergelson, B R; Gerasimov, A S; Tikhomirov, G V

2005-01-01

Power reactors can be used for partial short-term transmutation of radwaste. This transmutation is beneficial in terms of subsequent storage conditions for spent fuel in long-term storage facilities. CANDU-type reactors can transmute the main minor actinides from two or three reactors of the VVER-1000 type. A VVER-1000-type reactor can operate in a self-service mode with transmutation of its own actinides.

Separation of actinides and their transmutation

International Nuclear Information System (INIS)

Bouchard, M.; Bathelier, M.; Cousin, M.

1978-08-01

Neutron irradiation of long-half-life actinides for transmutation into elements with shorter half-life is investigated as a means to reduce the long-term hazards of these actinides. The effectiveness of the method is analysed by applying it to fission product solutions from the first extraction cycle of fuel reprocessing plants. Basic principles, separation techniques and transmutation efficiencies are studied and discussed in detail

Rare Earth element (REE) incorporation in natural calcite. Upper limits for actinide uptake in a secondary phase

International Nuclear Information System (INIS)

Stipp, S.L.S.; Christensen, J.T.; Waight, T.E.; Lakshtanov, L.Z.; Baker, J.A.

2006-01-01

Secondary minerals have the potential to sequester escaped actinides in the event of a radioactive waste repository failure, but currently, data to define their maximum uptake capacity are generally lacking. To estimate a maximum limit for solid solution in calcite, we took advantage of the behavioural similarities of the 4f-orbital lanthanides with some of the 5f-orbital actinides and used rare Earth element (REE) concentration as an analogue. A suite of 65 calcite samples, mostly pure single crystals, was assembled from a range of geological settings, ages and locations and analysed by isotope dilution MC-ICP-MS (multiple-collector inductively-coupled plasma mass spectroscopy). All samples were shown to contain significant lanthanide concentrations. The highest were in calcite formed from hydrothermal solutions and from carbonatite magma. Maximum total mole fraction of REE was 4.72 x 10 -4 , which represents one substituted atom for about 2000 Ca sites. In comparison, synthetic calcite, precipitated at growth rates slow enough to insure solid solution formation, incorporated 7.5 x 10 -4 mole fraction Eu(III). For performance assessment, we propose that 7.5 mmole substitution/kg calcite should be considered the upper limit for actinide incorporation in secondary calcite. The largest source of uncertainty in this estimate results from extrapolating lanthanide data to actinides. However, the data offer confidence that for waters in the hydrothermal temperature range, such as in the near-field, or at groundwater temperatures, such as in the far-field, if calcite formation is favoured and actinides are present, those with behaviour like the trivalent lanthanides, especially Am 3+ and Cm 3+ , will be incorporated. REE are abundant and widely distributed, and they have remained in calcite for millions of years. Thus, one can be certain that incorporated actinides will also remain immobilised in calcite formed in fractures and pore spaces, as long as solution conditions

Study on remain actinides recovery in pyro reprocessing

International Nuclear Information System (INIS)

Suharto, Bambang

1996-01-01

The spent fuel reprocessing by dry process called pyro reprocessing have been studied. Most of U, Pu and MA (minor actinides) from the spent fuel will be recovered and be fed back to the reactor as new fuel. Accumulation of remain actinides will be separated by extraction process with liquid cadmium solvent. The research was conducted by computer simulation to calculate the stage number required. The calculation's results showed on the 20 stages extractor more than 99% actinides can be separated. (author)

Use of fast-spectrum reactors for actinide burning

International Nuclear Information System (INIS)

Chang, Yoon I.

1991-01-01

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

3 and 4 oxidation state element solubilities in borosilicate glasses. Implement to actinides in nuclear glasses

International Nuclear Information System (INIS)

Cachia, J.N.

2005-12-01

In order to ensure optimal radionuclides containment, the knowledge of the actinide loading limits in nuclear waste glasses and also the comprehension of the solubilization mechanisms of these elements are essential. A first part of this manuscript deals with the study of the differences in solubility of the tri and tetravalent elements (actinides and surrogates) particularly in function of the melting temperature. The results obtained indicate that trivalent elements (La, Gd, Nd, Am, Cm) exhibit a higher solubility than tetravalent elements (Hf, Th, Pu). Consequently, it was planned to reduce plutonium at the oxidation state (III), the later being essentially tetravalent in borosilicate glasses. An innovating reduction process of multi-valent elements (cerium, plutonium) using silicon nitride has been developed in a second part of this work. Reduced plutonium-bearing glasses synthesized by Si 3 N 4 addition made it possible to double the plutonium solubility from 2 to 4 wt% at 1200 deg C. A structural approach to investigate the differences between tri and tetravalent elements was finally undertaken. These investigations were carried out by X-rays Absorption Spectroscopy (EXAFS) and NMR. Trivalent rare earth and actinide elements seem to behave as network modifiers while tetravalent elements rather present true intermediaries' behaviour. (author)

The effect of corrosion product colloids on actinide transport

International Nuclear Information System (INIS)

Gardiner, M.P.; Smith, A.J.; Williams, S.J.

1992-01-01

The near field of the proposed UK repository for ILW/LLW will contain containers of conditioned waste in contact with a cementious backfill. It will contain significant quantities of iron and steel, Magnox and Zircaloy. Colloids deriving from their corrosion products may possess significant sorption capacity for radioelements. If the colloids are mobile in the groundwater flow, they could act as a significant vector for activity transport into the far field. The desorption of plutonium and americium from colloidal corrosion products of iron and zirconium has been studied under chemical conditions representing the transition from the near field to the far field. Desorption R d values of ≥ 5 x 10 6 ml g -1 were measured for both actinides on these oxides and hydroxides when actinide sorption took place under the near-field conditions and desorption took place under the far-field conditions. Desorption of the actinides occurred slowly from the colloids under far-field conditions when the colloids had low loadings of actinide and more quickly at high loadings of actinide. Desorbed actinide was lost to the walls of the experimental vessel. (author)

Disposition of actinides released from high-level waste glass

International Nuclear Information System (INIS)

Ebert, W.L.; Bates, J.K.; Buck, E.C.; Gong, M.; Wolf, S.F.

1994-01-01

The disposition of actinide elements released from high-level waste glasses into a tuff groundwater in laboratory tests at 90 degrees C at various glass surface area/leachant volume ratios (S/V) between dissolved, suspended, and sorbed fractions has been measured. While the maximum release of actinides is controlled by the corrosion rate of the glass matrix, their solubility and sorption behavior affects the amounts present in potentially mobile phases. Actinide solubilities are affected by the solution pH and the presence of complexants released from the glass, such as sulfate, phosphate, and chloride, radiolytic products, such as nitrate and nitrite, and carbonate. Sorption onto inorganic colloids formed during lass corrosion may increase the amounts of actinides in solution, although subsequent sedimentation of these colloids under static conditions leads to a significant reduction in the amount of actinides in solution. The solution chemistry and observed actinide behavior depend on the S/V of the test. Tests at high S/V lead to higher pH values, greater complexant concentrations, and generate colloids more quickly than tests at low S/V. The S/V also affects the rate of glass corrosion

Research on the actinide chemistry in Nuclear Fuel Cycle

Energy Technology Data Exchange (ETDEWEB)

Song, Kyseok; Park, Yong Joon; Cho, Young Hwan; and others

2012-04-15

Fundamental technique to measure chemical behaviors and properties of lanthanide and actinide in radioactive waste is necessary for the development of pryochemical process. First stage, 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 equipments, 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. In the second stage, measurement system for physical properties at pyrochemical process such as viscosity, melting point and conductivity is established, and property database at different compositions of lanthanide and actinide is collected. And, both interactions between elements and properties with different potential are measured at binary composition of actinide-lanthanide in molten salt using electrochemical/spectroscopic integrated measurement system.

Analysis of the Gas Core Actinide Transmutation Reactor (GCATR)

Science.gov (United States)

Clement, J. D.; Rust, J. H.

1977-01-01

Design power plant studies were carried out for two applications of the plasma core reactor: (1) As a breeder reactor, (2) As a reactor able to transmute actinides effectively. In addition to the above applications the reactor produced electrical power with a high efficiency. A reactor subsystem was designed for each of the two applications. For the breeder reactor, neutronics calculations were carried out for a U-233 plasma core with a molten salt breeding blanket. A reactor was designed with a low critical mass (less than a few hundred kilograms U-233) and a breeding ratio of 1.01. The plasma core actinide transmutation reactor was designed to transmute the nuclear waste from conventional LWR's. The spent fuel is reprocessed during which 100% of Np, Am, Cm, and higher actinides are separated from the other components. These actinides are then manufactured as oxides into zirconium clad fuel rods and charged as fuel assemblies in the reflector region of the plasma core actinide transmutation reactor. In the equilibrium cycle, about 7% of the actinides are directly fissioned away, while about 31% are removed by reprocessing.

Nonaqueous method for dissolving lanthanide and actinide metals

International Nuclear Information System (INIS)

Crisler, L.R.

1975-01-01

Lanthanide and actinide beta-diketonate complex molecular compounds are produced by reacting a beta-diketone compound with a lanthanide or actinide element in the elemental metallic state in a mixture of carbon tetrachloride and methanol

Extraction chromatographic method for the separation of actinides and lanthanides using EDHBA grafted AXAD-16 polymer

Energy Technology Data Exchange (ETDEWEB)

Akhila Maheswari, M.; Subramanian, M.S. [Department of Chemistry, Indian Institute of Technology, Chennai (India)

2005-02-15

A new extraction chromatographic method has been developed by grafting chloromethylated polymer support with 4-ethoxy-N,N-dihexylbutanamide (EDHBA), for the selective extraction of U(VI), Th(IV), La(III) and Nd(III) from highly acidic matrices. The developed grafted polymer has been characterized using {sup 13}C-CPMAS NMR spectroscopy, FT-NIR spectroscopy and also by CHN elemental analysis. The water regaining capacity of the grafted polymer is studied by TGA measurements and the active participation of the amide moiety towards metal ion complexation has been confirmed by Far IR spectroscopy. For the quantitative extraction of metal ions to the resin phase, various physico-chemical parameters are optimized by both static and dynamic methods. The developed amide grafted polymeric matrix shows good distribution ratio values even at high acidities, with the maximum metal sorption capacity values being 0.36, 0.69, 0.32 and 0.42mmolg{sup -1} for U(VI), Th(IV), La(III) and Nd(III), respectively, at 6M HNO{sub 3} medium. The kinetics of metal ion phase equilibration is found to be moderately fast, with t{sub 1/2} values of <6min, for all the analytes of interest. The limits of analyte quantification (LOQ) using the developed method are in the range of 15-30{mu}gL{sup -1}. Moreover, the sequential separation of the sorbed actinides and lanthanides could be achieved by first eluting with 100mL of distilled water (for actinides) followed by elution with 20mL of 0.1M EDTA (for lanthanides). The selectivity behavior and the practical applicability of the developed resin are tested using synthetic low level nuclear reprocessing mixtures and also with monazite sand. The analytical data are within 3.8% relative standard deviation, reflecting the reproducibility and reliability of the developed method.

Pyridinium bis(pyridine-κNtetrakis(thiocyanato-κNferrate(III

Directory of Open Access Journals (Sweden)

Sergii I. Shylin

2013-06-01

Full Text Available In the title compound, (C5H6N[Fe(NCS4(C5H5N2], the FeIII ion is coordinated by four thiocyanate N atoms and two pyridine N atoms in a trans arrangement, forming an FeN6 polyhedron with a slightly distorted octahedral geometry. Charge balance is achieved by one pyridinium cation bound to the complex anion via N—H...S hydrogen bonding. The asymmetric unit consists of one FeIII cation, four thiocyanate anions, two coordinated pyridine molecules and one pyridinium cation. The structure exhibits π–π interactions between pyridine rings [centroid–centroid distances = 3.7267 (2, 3.7811 (2 and 3.8924 (2 Å]. The N atom and a neighboring C atom of the pyridinium cation are statistically disordered with an occupancy ratio of 0.58 (2:0.42 (2.

Biotransformation of uranium and other actinides in radioactive wastes

International Nuclear Information System (INIS)

Francis, A.J.

1998-01-01

Microorganisms affect the solubility, bioavailability, and mobility of actinides in radioactive wastes. Under appropriate conditions, actinides are solubilized or stabilized by the direct enzymatic or indirect nonenzymatic actions of microorganisms. Biotransformation of various forms of uranium (ionic, inorganic, and organic complexes) by aerobic and anaerobic microorganisms has been extensively studied, whereas limited information is available on other important actinides (Th, Np, Pu, and Am). Fundamental information on the mechanisms of biotransformation of actinides by microbes under various environmental conditions will be useful in predicting the long-term performance of waste repositories and in developing strategies for waste management and remediation of contaminated sites. (orig.)

Strategies for minority actinides transmutation in fast reactors

International Nuclear Information System (INIS)

Perez-Martin, S.; Martin-Fuertes, F.; Alvarez-Velarde, F.

2010-01-01

Presentation of the strategies that can be followed in fast reactors designed for the fourth generation to reduce the inventory of minority actinides generated in current light water reactors, as the actinides generation in fast reactor.

Actinide-handling experience for training and education of future expert under J-ACTINET

International Nuclear Information System (INIS)

Osaka, Masahiko; Sato, Isamu; Miwa, Shuhei; Konashi, Kenji; Li, Dexin; Homma, Yoshiya; Yamamura, Tomoo; Hayashi, Hirokazu; Minato, Kazuo; Sekimoto, Syun; Kubota, Takumi; Fukutani, Satoshi; Hori, Junichi; Okumura, Ryo; Uehara, Akihiro; Fujii, Toshiyuki; Yamana, Hajimu; Kurosaki, Ken; Muta, Hiroaki; Ohishi, Yuji; Yamanaka, Shinsuke; Uno, Masayoshi; Yaita, Tsuyoshi

2011-01-01

Summer schools for future experts have successfully been completed under Japan Actinide Network (J-ACTINET) for the purpose of development of human resources who are expected to be engaged in every areas of actinide-research/engineering. The first summer school was held in Ibaraki-area in August 2009, followed by the second one in Kansai-area in August 2010. Two summer schools have focused on actual experiences of actinides in actinide-research fields for university students and young researchers/engineers as an introductory course of actinide-researches. Many efforts were made to awaken interests into actinide-researches inside the participants during short periods of schools, 3 to 4 days. As actinides must be handled inside special apparatuses such as an air-tight globe-box with well-trained and qualified technicians, programs were optimized for effective experiences of actinides-handling. Several quasi actinide-handling experiences at the actinide-research fields have attracted attentions of participants at the first school in Ibaraki-area. The actual experiments using actinides-containing solutions have been carried out at the second school in Kansai-area. Future summer schools will be held every year for the sustainable human resource development in various actinide-research fields, together with other training and education programs conducted by the J-ACTINET. (author)

Actinide separation chemistry in nuclear waste streams and materials

International Nuclear Information System (INIS)

1997-12-01

The separation of actinide elements from various waste materials, produced either in nuclear fuel cycles or in past nuclear weapons production, represents a significant issue facing developed countries. Improvements in the efficiencies of the separation processes can be expected to occur as a result of better knowledge of the elements in these complex matrices. The Nuclear Science Committee of the OECD/NEA has established a task force of experts in actinide separation chemistry to review current and developing separation techniques and chemical processes. The report consist of eight chapters. In Chapter 1 the importance of actinide separation chemistry in the fields of waste management and its background are summarized.In Chapter 2 the types of waste streams are classified according to their relative importance, by physical form and by source of actinides. The basic data of actinide chemical thermodynamics, such as oxidation states, hydrolysis, complexation, sorption, Gibbs energies of formation, and volatility, were collected and are presented in Chapter 3. Actinide analyses related to separation processes are also mentioned in this chapter. The state of the art of actinide separation chemistry is classified in three groups, including hydrometallurgy, pyrochemical process and process based on fields, and is described in Chapter 4 along with the relationship of kinetics to separations. In Chapter 5 basic chemistry research needs and the inherent limitation on separation processes are discussed. Prioritization of research and development is discussed in Chapter 6 in the context of several attributes of waste management problems. These attributes include: mass or volume of waste; concentration of the actinide in the waste; expected difficulty of treating the wastes; short-term hazard of the waste; long-term hazard of the waste; projected cost of treatment; amount of secondary waste. Based on the priority, recommendations were made for the direction of future research

Actinide separation chemistry in nuclear waste streams and materials

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-12-01

The separation of actinide elements from various waste materials, produced either in nuclear fuel cycles or in past nuclear weapons production, represents a significant issue facing developed countries. Improvements in the efficiencies of the separation processes can be expected to occur as a result of better knowledge of the elements in these complex matrices. The Nuclear Science Committee of the OECD/NEA has established a task force of experts in actinide separation chemistry to review current and developing separation techniques and chemical processes. The report consist of eight chapters. In Chapter 1 the importance of actinide separation chemistry in the fields of waste management and its background are summarized.In Chapter 2 the types of waste streams are classified according to their relative importance, by physical form and by source of actinides. The basic data of actinide chemical thermodynamics, such as oxidation states, hydrolysis, complexation, sorption, Gibbs energies of formation, and volatility, were collected and are presented in Chapter 3. Actinide analyses related to separation processes are also mentioned in this chapter. The state of the art of actinide separation chemistry is classified in three groups, including hydrometallurgy, pyrochemical process and process based on fields, and is described in Chapter 4 along with the relationship of kinetics to separations. In Chapter 5 basic chemistry research needs and the inherent limitation on separation processes are discussed. Prioritization of research and development is discussed in Chapter 6 in the context of several attributes of waste management problems. These attributes include: mass or volume of waste; concentration of the actinide in the waste; expected difficulty of treating the wastes; short-term hazard of the waste; long-term hazard of the waste; projected cost of treatment; amount of secondary waste. Based on the priority, recommendations were made for the direction of future research

Impact of minor actinide recycling on sustainable fuel cycle options

Energy Technology Data Exchange (ETDEWEB)

Heidet, F.; Kim, T. K.; Taiwo, T. A.

2017-11-01

The recent Evaluation and Screening study chartered by the U.S. Department of Energy, Office of Nuclear Energy, has identified four fuel cycle options as being the most promising. Among these four options, the two single-stage fuel cycles rely on a fast reactor and are differing in the fact that in one case only uranium and plutonium are recycled while in the other case minor actinides are also recycled. The two other fuel cycles are two-stage and rely on both fast and thermal reactors. They also differ in the fact that in one case only uranium and plutonium are recycled while in the other case minor actinides are also recycled. The current study assesses the impact of recycling minor actinides on the reactor core design, its performance characteristics, and the characteristics of the recycled material and waste material. The recycling of minor actinides is found not to affect the reactor core performance, as long as the same cycle length, core layout and specific power are being used. One notable difference is that the required transuranics (TRU) content is slightly increased when minor actinides are recycled. The mass flows are mostly unchanged given a same specific power and cycle length. Although the material mass flows and reactor performance characteristics are hardly affected by recycling minor actinides, some differences are observed in the waste characteristics between the two fuel cycles considered. The absence of minor actinides in the waste results in a different buildup of decay products, and in somewhat different behaviors depending on the characteristic and time frame considered. Recycling of minor actinides is found to result in a reduction of the waste characteristics ranging from 10% to 90%. These results are consistent with previous studies in this domain and depending on the time frame considered, packaging conditions, repository site, repository strategy, the differences observed in the waste characteristics could be beneficial and help improve

Proceedings of the symposium Actinides 2006 - Basic Science, Applications and Technology

International Nuclear Information System (INIS)

Blobaum, Kerri J.M.; Chandler, Elaine A.; Havela, Ladislav; Maple, M. Brian; Neu, Mary P.

2007-01-01

These proceedings from the September 2006 symposium includes papers presented on experimental and modeling work with the intention of broadening understanding of the field of actinide research. Actinides have gained attention recently because of their roles in the threat of nuclear terrorism (e.g., 'dirty bombs') and the use of nuclear power to offset fossil fuel consumption. Actinide science is the study of the elements with atomic numbers in the range of 90 to 103, which includes uranium and plutonium. Beyond the well-known nuclear reactions of these heavy radioactive metals, the large electron clouds with 5f electrons in the outer shell yield fascinating and complex chemistries, crystal structures, and physical properties. Traditionally, actinide research has been divided among three scientific disciplines: chemistry (nuclear chemistry and radiochemistry); physics (condensed matter physics and electronic structure); and materials science (metallurgy). Modern actinide research, however, has become an interdisciplinary blend of these traditional fields, and it also incorporates developing fields such as environmental chemistry and superconductivity. Improved scientific understanding of actinides is needed for development of materials for actinide detection and nuclear fuels, and for safer management of nuclear waste. Recently, there has been a resurgence of actinide science at national laboratories and universities. The current multidisciplinary approach to actinide science lays the groundwork for understanding the connection between the 5f electronic structure and observed chemical reactions and physical properties such as structural phase transformations and novel ground states. This work provides many opportunities for new researchers in actinide science. These proceedings gather 25 selected papers among the 53 presentations given at this symposium

A contribution to the study of the extraction of mineral acids and of actinide (IV) and (VI) cations by N,N-dialkylamides

International Nuclear Information System (INIS)

Condamines, N.

1990-03-01

N,N-dialkylamides are alternate extractants to tributylphosphate, TBP, for the actinides separation in nuclear fuel reprocessing. N,N-di (2-ethyl hexyl) butyramide and N,N-di (2 ethyl hexyl) isobutyramide are selected for their sufficient extraction and partition ability towards actinides (IV) and (VI) without coextracting fission products. Mechanisms of HNO 3 , UO 2 2+ , Pu 4+ , Th 4+ are investigated. Nitric acid extraction is due to the competitive formation of the species (HNO 3 )L 2 , (HNO 3 )L, (HNO 3 ) 2 L (L: DOBA or DOiBA). An hydrogen bond is the driving force of the transfer. For low acidity media, amides are neutral extractants. Physical interactions, between free ligand and metallic complex, arise for high amide concentrations. Taking into account the non-ideality of the organic medium by a hard spheres mixture model, we estimate that such interactions are far from negligible and very specific to the amide group. Unlike TBP, when increasing acidity, amides behave as anionic extractants. DOBA and DOiBA appear to be satisfactory extractants for fuel reprocessing [fr

Casting of metallic fuel containing minor actinide additions

International Nuclear Information System (INIS)

Trybus, C.L.; Henslee, S.P.; Sanecki, J.E.

1992-01-01

A significant attribute of the Integral Fast Reactor (IFR) concept is the transmutation of long-lived minor actinide fission products. These isotopes require isolation for thousands of years, and if they could be removed from the waste, disposal problems would be reduced. The IFR utilizes pyroprocessing of metallic fuel to separate auranium, plutonium, and the minor actinides from nonfissionable constituents. These materials are reintroduced into the fuel and reirradiated. Spent IFR fuel is expected to contain low levels of americium, neptunium, and curium because the hard neutron spectrum should transmute these isotopes as they are produced. This opens the possibility of using an IFR to trnasmute minor actinide waste from conventional light water reactors (LWRs). A standard IFR fuel is based on the alloy U-20% Pu-10% Zr (in weight percent). A metallic fuel system eases the requirements for reprocessing methods and enables the minor actinide metals to be incorporated into the fuel with simple modifications to the basic fuel casting process. In this paper, the authors report the initial casting experience with minor actinide element addition to an IFR U-Pu-Zr metallic fuel

Calculated Atomic Volumes of the Actinide Metals

DEFF Research Database (Denmark)

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....

Citrate based ''TALSPEAK'' lanthanide-actinide separation process

International Nuclear Information System (INIS)

Del Cul, G.D.; Bond, W.D.; Toth, L.M.; Davis, G.D.; Dai, S.; Metcalf, D.H.

1994-09-01

The potential hazard posed to future generations by long-lived radionuclides such as the transuranic elements (TRU) is perceived as a major problem associated with the use of nuclear power. TRU wastes have to remain isolated from the environment for ''geological'' periods of time. The costs of building, maintaining, and operating a ''geological TRU repository'' can be very high. Therefore, there are significant economical advantages in segregating the relatively low volume of TRU wastes from other nuclear wastes. The chemical behavior of lanthanides and actinides, 4f and 5f elements respectively, is rather similar. As a consequence, the separation of these two groups is difficult. The ''TALSPEAK'' process (Trivalent Actinide Lanthanide Separations by Phosphorus-reagent Extraction from Aqueous Complexes) is one of the few means available to separate the trivalent actinides from the lanthanides. The method is based on the preferential complexation of the trivalent actinides by an aminopolyacetic acid. Cold experiments showed that by using citric acid the deleterious effects produced by impurities such as zirconium are greatly reduced

Research on Actinides in Nuclear Fuel Cycles

International Nuclear Information System (INIS)

Song, Kyu Seok; Park, Yong Joon; Cho, Young Hwan

2010-04-01

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

Research on Actinides in Nuclear Fuel Cycles

Energy Technology Data Exchange (ETDEWEB)

Song, Kyu Seok; Park, Yong Joon; Cho, Young Hwan

2010-04-15

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

Proposal for experiments with actinide elements

International Nuclear Information System (INIS)

Sanchez, R.G.

1994-01-01

An analytical study was conducted in which critical masses for some actinide isotopes were calculated with the Monte Carlo Neutron Photon (MCNP) Transport computer code. Different spherical computer models were used for even- and odd-neutron nuclides. Critical masses obtained are tabulated for Np-237, Pu-242, Am-241, Am-243, Pu-241, and Am-242m, together with indirect experimental data. Experimental data are needed for actinides with odd number of neutrons

complex formation of americium (III) with humic acid

International Nuclear Information System (INIS)

Zhang Yingjie; Zhao Xin; Wei Liansheng; Lin Zhangji

1998-01-01

The presence of humic substances in natural waters will modify the migration behavior of actinides in the geosphere due to the strong reaction properties of these ligands with actinides. Therefore, the possible reactions of humic acid with actinides have been studied widely in recent years. The complex formation of Am(III) with humic acid is studied with solvent extraction technique. The experiments are performed in the pH range from 4.0 to 8.0 in 0.1 mol/kg NaClO 4 solution at ambient temperature. Experimental results show that the complex formation constants of Am(III) with humic acid are varied with the variation of pH value in solution. 1:2 complex is obtained in the experiments and the complex formation constants determined at each pH are: lgβ 1 = 6.56 +- 0.05, lgβ 2 = 10.77 +- 0.31 at pH 4.0. lgβ 1 = 7.94 +- 0.11, lgβ 2 = 11.80 +- 0.21 at pH = 5.0. lgβ 1 = 10.74 +- 0.28, lgβ 2 = 12.88 +- 0.49 at pH = 6.0. lgβ 1 = 12.85 +- 0.30, lgβ 2 = 14.80 +- 0.62 at pH = 7.0. lgβ 1 = 14.88 +- 0.48, lgβ 2 = 15.65 +- 0.69 at pH = 8.0, respectively. The dependence of the complex formation constant on pH is: lgβ 1 = 2.16 (+-0.98)pH-2.34(+-0.93),lgβ 2 1.28(+-1.04)pH+5.52(+-1.21), respectively

Actinide science with soft x-ray synchrotron radiation

International Nuclear Information System (INIS)

Shuh, D.

2002-01-01

Several workshops, some dating back more than fifteen years, recognised both the potential scientific impact and opportunities that would be made available by the capability to investigate actinide materials in the vacuum ultraviolet (VUV)/soft X-ray region of the synchrotron radiation (SR) spectrum. This spectral region revolutionized the approach to surface materials chemistry and physics nearly two decades ego. The actinide science community was unable to capitalize on these SR methodologies for the study of actinide materials until recently because of radiological safety concerns. ,The Advanced Light Source (ALS) at LBNL is a third-generation light source providing state-of-the-art performance in the VUV/soft X-ray region. Along with corresponding improvements in detector and vacuum technology, the ALS has rendered experiments with small amounts of actinide materials possible. In particular, it has been the emergence and development of micro-spectroscopic techniques that have enabled investigations of actinide materials at the ALS. The primary methods for the experimental investigation of actinide materials in the VUV/soft X-ray region are the complementary photoelectron spectroscopies, near-edge X-ray absorption fine structure (NEXAFS) and X-ray emission spectroscopy (XES) techniques. Resonant photo-emission is capable of resolving the 5f electron contributions to actinide bonding and can be used to characterise the electronic structure of actinide materials. This technique is clearly a most important methodology afforded by the tunable SR source. Core level and valence band photoelectron spectroscopies are valuable for the characterisation of the electronic properties of actinide materials, as well as for general analytical purposes. High-resolution core-level photo-emission and resonant photo-emission measurements from the a (monoclinic) and δ (FCC) allotropic phases of plutonium metal have been collected on beam line 7.0 at the ALS and the spectra show

J-ACTINET activities of training and education for actinide science research

International Nuclear Information System (INIS)

Miato, Kazuo; Konashi, Kenji; Yamana, Hajimu; Yamanaka, Shinsuke; Nagasaki, Shinya; Ikeda, Yasuhisa; Sato, Seichi; Arita, Yuji; Idemitsu, Kazuya; Koyama, Tadafumi

2011-01-01

Actinide science research is indispensable to maintain sustainable development of innovative nuclear technology, especially advanced fuels, partitioning/reprocessing, and waste management. For actinide science research, special facilities with containment and radiation shields are needed to handle actinide materials since actinide elements are γ-, α- and neutron-emitters. The number of facilities for actinide science research has been decreased, especially in universities, due to the high maintenance cost. J-ACTINET was established in 2008 to promote and facilitate actinide science research in close cooperation with the facilities and to foster many of young scientists and engineers to be actively engaged in the fields of actinide science. The research program was carried out, through which young researchers were expected to learn how to make experiments with advanced experimental tools and to broaden their horizons. The summer schools and computational science school were held to provide students, graduate students, and young researchers with the opportunities to come into contact with actinide science research. In these schools, not only the lectures, but also the practical exercises were made as essential part. The overseas dispatch program was also carried out, where graduate students and young researchers were sent to the international summer schools and conferences. (author)

Protactinium and the intersection of actinide and transition metal chemistry

Energy Technology Data Exchange (ETDEWEB)

Wilson, Richard E.; De Sio, Stephanie; Vallet, Valérie

2018-02-12

The role of the 5f and 6d orbitals in the chemistry of the actinide elements has been of considerable interest since their discovery and synthesis. Relativistic effects cause the energetics of the 5f and 6d orbitals to change as the actinide series is traversed left to right imparting a rich and complex chemistry. The 5f and 6d atomic states cross in energy at protactinium (Pa), making it a potential intersection between transition metal and actinide chemistries. Herein, we report the synthesis of a Pa-peroxo cluster, A(6)(Pa4O(O-2)(6)F-12) [A = Rb, Cs, (CH3)(4)N], formed in pursuit of an actinide polyoxometalate. Quantum chemical calculations at the density functional theory level demonstrate equal 5f and 6d orbital participation in the chemistry of Pa and increasing 5f orbital participation for the heavier actinides. Periodic changes in orbital character to the bonding in the early actinides highlights the influence of the 5f orbitals in their reactivity and chemical structure.

Actinide removal from molten salts by chemical oxidation and salt distillation

Energy Technology Data Exchange (ETDEWEB)

McNeese, J.A.; Garcia, E.; Dole, V.R. [Los Alamos National Laboratory, NM (United States)] [and others

1995-10-01

Actinide removal from molten salts can be accomplished by a two step process where the actinide is first oxidized to the oxide using a chemical oxidant such as calcium carbonate or sodium carbonate. After the actinide is precipitated as an oxide the molten salt is distilled away from the actinide oxides leaving a oxide powder heel and an actinide free distilled salt that can be recycled back into the processing stream. This paper discusses the chemistry of the oxidation process and the physical conditions required to accomplish a salt distillation. Possible application of an analogous process sequence for a proposed accelerator driven transmutation molten salt process is also discussed.

Actinide removal from molten salts by chemical oxidation and salt distillation

International Nuclear Information System (INIS)

McNeese, James A.; Garcia, Eduardo; Dole, Vonda R.; Griego, Walter J.

1995-01-01

Actinide removal from molten salts can be accomplished by a two step process where the actinide is first oxidized to the oxide using a chemical oxidant such as calcium carbonate or sodium carbonate. After the actinide is precipitated as an oxide the molten salt is distilled away from the actinide oxides leaving a oxide powder heel and an actinide free distilled salt that can be recycled back into the processing stream. This paper discusses the chemistry of the oxidation process and the physical conditions required to accomplish a salt distillation. Possible application of an analogous process sequence for a proposed accelerator driven transmutation molten salt process is also discussed

Organometallic neptunium(III) complexes

Science.gov (United States)

Dutkiewicz, Michał S.; Farnaby, Joy H.; Apostolidis, Christos; Colineau, Eric; Walter, Olaf; Magnani, Nicola; Gardiner, Michael G.; Love, Jason B.; Kaltsoyannis, Nikolas; Caciuffo, Roberto; Arnold, Polly L.

2016-08-01

Studies of transuranic organometallic complexes provide a particularly valuable insight into covalent contributions to the metal-ligand bonding, in which the subtle differences between the transuranium actinide ions and their lighter lanthanide counterparts are of fundamental importance for the effective remediation of nuclear waste. Unlike the organometallic chemistry of uranium, which has focused strongly on UIII and has seen some spectacular advances, that of the transuranics is significantly technically more challenging and has remained dormant. In the case of neptunium, it is limited mainly to NpIV. Here we report the synthesis of three new NpIII organometallic compounds and the characterization of their molecular and electronic structures. These studies suggest that NpIII complexes could act as single-molecule magnets, and that the lower oxidation state of NpII is chemically accessible. In comparison with lanthanide analogues, significant d- and f-electron contributions to key NpIII orbitals are observed, which shows that fundamental neptunium organometallic chemistry can provide new insights into the behaviour of f-elements.

Use of fast reactors for actinide transmutation

International Nuclear Information System (INIS)

1993-03-01

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

The chemistry of the actinide elements. Volume I

International Nuclear Information System (INIS)

Katz, J.J.; Seaborg, G.T.; Morss, L.R.

1986-01-01

The Chemistry of the Actinide Elements is a comprehensive, contemporary and authoritative exposition of the chemistry and related properties of the 5f series of elements: actinium, thorium, protactinium, uranium and the first eleven. This second edition has been completely restructured and rewritten to incorporate current research in all areas of actinide chemistry and chemical physics. The descriptions of each element include accounts of their history, separation, metallurgy, solid-state chemistry, solution chemistry, thermo-dynamics and kinetics. Additionally, separate chapters on spectroscopy, magnetochemistry, thermodynamics, solids, the metallic state, complex ions and organometallic compounds emphasize the comparative chemistry and unique properties of the actinide series of elements. Comprehensive lists of properties of all actinide compounds and ions in solution are given, and there are special sections on such topics as biochemistry, superconductivity, radioisotope safety, and waste management, as well as discussion of the transactinides and future elements

Thermochemical and thermophysical properties of minor actinide compounds

International Nuclear Information System (INIS)

Minato, Kazuo; Takano, Masahide; Otobe, Haruyoshi; Nishi, Tsuyoshi; Akabori, Mitsuo; Arai, Yasuo

2009-01-01

Burning or transmutation of minor actinides (MA: Np, Am, Cm) that are classified as the high-level radioactive waste in the current nuclear fuel cycle is an option for the advanced nuclear fuel cycle. Although the thermochemical and thermophysical properties of minor actinide compounds are essential for the design of MA-bearing fuels and analysis of their behavior, the experimental data on minor actinide compounds are limited. To support the research and development of the MA-bearing fuels, the property measurements were carried out on minor actinide nitrides and oxides. The lattice parameters and their thermal expansions were measured by high-temperature X-ray diffractometry. The specific heat capacities were measured by drop calorimetry and the thermal diffusivities by laser-flash method. The thermal conductivities were determined by the specific heat capacities, thermal diffusivities and densities. The oxygen potentials were measured by electromotive force method.

Design and synthesis of some polyaminopolycarboxylic acids and the structural influence of their anions on the separation of actinides and lanthanides

International Nuclear Information System (INIS)

Tse, P.K.

1983-01-01

Investigation of some methods for the preparation of four polyaminopolycarboxylic acids: thiobis(ethylenenitrilo)-N,N,N',N'-tetraacetic acid, N,N-bis(2-aminoethyl)aniline-N',N',N'',N''-tetraacetic acid, bis(3-aminopropyl)ether-N,N,N',N'-tetraacetic acid and N,N-bis[N',N'-dicarboxymethyl-3-aminopropyl]-N-methylammonioacetate are reported. The coordinating properties of their anions with regard to lanthanide ions have been examined. Polyaminopolycarboxylates form 1:1 chelate species with trivalent lanthanide ions in aqueous media. The stability constants of their metal chelate species depend upon the size of the chelating rings formed, the basicity of the middle atom in the chain, and the number of coordination points between anion and metal cation. Tracer level 241 Am- 155 Eu cation-exchange experiments explore how the relative magnitude of the chelate stability constants affects the separation of members of the lanthanide and actinide series

A contribution to the study of the extraction of mineral acids and of actinide (IV) and (VI) cations by N,N-dialkylamides; Contribution a l'etude de l'extraction d'acides mineraux et de cations actinides aux degres d'oxydation (IV) et (VI) par des N,N-dialkylamides

Energy Technology Data Exchange (ETDEWEB)

Condamines, N

1990-03-15

N,N-dialkylamides are alternate extractants to tributylphosphate, TBP, for the actinides separation in nuclear fuel reprocessing. N,N-di (2-ethyl hexyl) butyramide and N,N-di (2 ethyl hexyl) isobutyramide are selected for their sufficient extraction and partition ability towards actinides (IV) and (VI) without coextracting fission products. Mechanisms of HNO{sub 3}, UO{sub 2}{sup 2+}, Pu{sup 4+}, Th{sup 4+} are investigated. Nitric acid extraction is due to the competitive formation of the species (HNO{sub 3})L{sub 2}, (HNO{sub 3})L, (HNO{sub 3}){sub 2}L (L: DOBA or DOiBA). An hydrogen bond is the driving force of the transfer. For low acidity media, amides are neutral extractants. Physical interactions, between free ligand and metallic complex, arise for high amide concentrations. Taking into account the non-ideality of the organic medium by a hard spheres mixture model, we estimate that such interactions are far from negligible and very specific to the amide group. Unlike TBP, when increasing acidity, amides behave as anionic extractants. DOBA and DOiBA appear to be satisfactory extractants for fuel reprocessing.

Spectroscopic and Kinetic Characterization of Peroxidase-Like π-Cation Radical Pinch-Porphyrin-Iron(III Reaction Intermediate Models of Peroxidase Enzymes

Directory of Open Access Journals (Sweden)

Samuel Hernández Anzaldo

2016-06-01

Full Text Available The spectroscopic and kinetic characterization of two intermediates from the H2O2 oxidation of three dimethyl ester [(proto, (meso, (deuteroporphyrinato (picdien]Fe(III complexes ([FePPPic], [FeMPPic] and [FeDPPic], respectively pinch-porphyrin peroxidase enzyme models, with s = 5/2 and 3/2 Fe(III quantum mixed spin (qms ground states is described herein. The kinetic study by UV/Vis at λmax = 465 nm showed two different types of kinetics during the oxidation process in the guaiacol test for peroxidases (1–3 + guaiacol + H2O2 → oxidation guaiacol products. The first intermediate was observed during the first 24 s of the reaction. When the reaction conditions were changed to higher concentration of pinch-porphyrins and hydrogen peroxide only one type of kinetics was observed. Next, the reaction was performed only between pinch-porphyrins-Fe(III and H2O2, resulting in only two types of kinetics that were developed during the first 0–4 s. After this time a self-oxidation process was observed. Our hypotheses state that the formation of the π-cation radicals, reaction intermediates of the pinch-porphyrin-Fe(III family with the ligand picdien [N,N’-bis-pyridin-2-ylmethyl-propane-1,3-diamine], occurred with unique kinetics that are different from the overall process and was involved in the oxidation pathway. UV-Vis, 1H-NMR and ESR spectra confirmed the formation of such intermediates. The results in this paper highlight the link between different spectroscopic techniques that positively depict the kinetic traits of artificial compounds with enzyme-like activity.

Lattice effects in the light actinides

International Nuclear Information System (INIS)

Lawson, A.C.; Cort, B.; Roberts, J.A.; Bennett, B.I.; Brun, T.O.; Dreele, R.B. von; Richardson, J.W. Jr.

1998-01-01

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

3 and 4 oxidation state element solubilities in borosilicate glasses. Implement to actinides in nuclear glasses; Solubilite des elements aux degres d'oxydation (3) et (4) dans les verres de borosilicate. Application aux actinides dans les verres nucleaires

Energy Technology Data Exchange (ETDEWEB)

Cachia, J.N

2005-12-15

In order to ensure optimal radionuclides containment, the knowledge of the actinide loading limits in nuclear waste glasses and also the comprehension of the solubilization mechanisms of these elements are essential. A first part of this manuscript deals with the study of the differences in solubility of the tri and tetravalent elements (actinides and surrogates) particularly in function of the melting temperature. The results obtained indicate that trivalent elements (La, Gd, Nd, Am, Cm) exhibit a higher solubility than tetravalent elements (Hf, Th, Pu). Consequently, it was planned to reduce plutonium at the oxidation state (III), the later being essentially tetravalent in borosilicate glasses. An innovating reduction process of multi-valent elements (cerium, plutonium) using silicon nitride has been developed in a second part of this work. Reduced plutonium-bearing glasses synthesized by Si{sub 3}N{sub 4} addition made it possible to double the plutonium solubility from 2 to 4 wt% at 1200 deg C. A structural approach to investigate the differences between tri and tetravalent elements was finally undertaken. These investigations were carried out by X-rays Absorption Spectroscopy (EXAFS) and NMR. Trivalent rare earth and actinide elements seem to behave as network modifiers while tetravalent elements rather present true intermediaries' behaviour. (author)

Non-compound nucleus fission in actinide and pre-actinide regions

Indian Academy of Sciences (India)

Data on the evaporation residue cross-sections, in addition to those on mass and angular distributions, are necessary for better understanding of the contribution from non-compound nucleus fission in the pre-actinide region. Measurement of mass-resolved angular distribution of fission products in 20Ne+232Th reaction ...

Special actinide nuclides: Fuel or waste?

International Nuclear Information System (INIS)

Srinivasan, M.; Rao, K.S.; Dingankar, M.V.

1989-01-01

The special actinide nuclides such as Np, Cm, etc. which are produced as byproducts during the operation of fission reactors are presently looked upon as 'nuclear waste' and are proposed to be disposed of as part of high level waste in deep geological repositories. The potential hazard posed to future generations over periods of thousands of years by these long lived nuclides has been a persistent source of concern to critics of nuclear power. However, the authors have recently shown that each and every one of the special actinide nuclides is a better nuclear fuel than the isotopes of plutonium. This finding suggests that one does not have to resort to exotic neutron sources for transmuting/incinerating them as proposed by some researchers. Recovery of the special actinide elements from the waste stream and recycling them back into conventional fission reactors would eliminate one of the stigmas attached to nuclear energy

Neutron scattering studies of the actinides

International Nuclear Information System (INIS)

Lander, G.H.

1979-01-01

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 UO 2 , 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

Critical analysis of the data on complexation of lanthanides and actinides by natural organic matter: particular case of humic substances

International Nuclear Information System (INIS)

Reiller, P.

2010-01-01

This document proposes a critical analysis of the models that describe the actinides and lanthanides complexation by natural organic matter in general and by humic substances in particular. In order to better delimit the particular properties of these substances the most influent physical and chemical properties on complexation are recalled as a preamble. Models as well as data that has been used are reviewed, compiled, and eventually compared to independent data in order to identify (i) their application domain, (ii) the possible simplifications which permit to obtain operational models, (iii) the conditions in which simplifications cannot be ascertained yet, and (iv) the data or fields of knowledge which are still too uncertain. A comparison between the different models is proposed in order to adapt parameters from one model to another minimising the experimental acquisitions, or at least to focus on missing data. Usually, data on the complexation of free ions M z+ are reliable; as soon as hydrolysis, or competition with another ligand in general, in at stake data are much less reliable. Predictions from models are much more uncertain: formation of mixed complexes with hydroxide or carbonate anions is not univocal whatever the modelling strategy. Hints for transfer functions between models which are believed to be incompatible could be explored in order to justify necessary simplifications for using operational modelling. Influence on the solubility of oxides could be quantified, but it is difficult to clearly separate it from colloidal particles stabilisation. The account of the competition between cations by the models has also been tested. In view of the small number of available experimental data there still lie some uncertainties especially for the media that are close to neutrality and in the case of competition with magnesium, but overall in the case of the competition with aluminium and iron. The influence of redox activity of humic substances is also

Successive change regularity of actinide properties with atomic number

International Nuclear Information System (INIS)

Yang Xuexian

1990-08-01

The development and achievements on chemistry of actinide elements are summarised. The relations of properties of actinides to their electronic configurations of valence electronic shells are discussed. Some anomalies of solid properties, the radius contraction, the stable state effect of f 7n -orbits (n = 0, 1, 2) and the tetrad effect of oxidation states, etc., with atomic number (Z) are described. 31 figures appended show directly the successive change regularity of actinide properties with Z

MICROBIAL TRANSFORMATIONS OF TRU AND MIXED WASTES: ACTINIDE SPECIATION AND WASTE VOLUME REDUCTION

Energy Technology Data Exchange (ETDEWEB)

Francis, A.J.; Dodge, C.J.

2006-06-01

The overall goals of this research project are to determine the mechanism of microbial dissolution and stabilization of actinides in Department of Energy’s (DOE) TRU wastes, contaminated sludges, soils, and sediments. This includes (i) investigations on the fundamental aspects of microbially catalyzed radionuclide and metal transformations (oxidation/reduction reactions, dissolution, precipitation, chelation); (ii) understanding of the microbiological processes that control speciation and alter the chemical forms of complex inorganic/organic contaminant mixtures; and (iii) development of new and improved microbially catalyzed processes resulting in immobilization of metals and radionuclides in the waste with concomitant waste volume reduction.

A Summary of Actinide Enrichment Technologies and Capability Gaps

Energy Technology Data Exchange (ETDEWEB)

Patton, Bradley D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Robinson, Sharon M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2017-01-01

The evaluation performed in this study indicates that a new program is needed to efficiently provide a national actinide radioisotope enrichment capability to produce milligram-to-gram quantities of unique materials for user communities. This program should leverage past actinide enrichment, the recent advances in stable isotope enrichment, and assessments of the future requirements to cost effectively develop this capability while establishing an experience base for a new generation of researchers in this vital area. Preliminary evaluations indicate that an electromagnetic isotope separation (EMIS) device would have the capability to meet the future needs of the user community for enriched actinides. The EMIS technology could be potentially coupled with other enrichment technologies, such as irradiation, as pre-enrichment and/or post-enrichment systems to increase the throughput, reduce losses of material, and/or reduce operational costs of the base EMIS system. Past actinide enrichment experience and advances in the EMIS technology applied in stable isotope separations should be leveraged with this new evaluation information to assist in the establishment of a domestic actinide radioisotope enrichment capability.

Spectroscopic and thermodynamic study of the complexation of Cm(III) and Eu(III) with hydrophilic bis-triazinyl pyridines

International Nuclear Information System (INIS)

Ruff, Christian

2013-01-01

In the present work the complexation of Cm(III) and Eu(III) with a hydrophilic 2,6-bis-(1,2,4-triazinyl)-pyridine (aq-BTP) is studied. Aq-BTP complexes actinides(III) selectively over lanthanides(III) in nitric acid solution. The object of this work is the identification and the spectroscopic and thermodynamic characterization of the Cm(III) and Eu(III) complex species present in solution. The results should contribute to a better fundamental understanding of the driving force behind BTPs selectivity towards trivalent actinides on a molecular level. Time-resolved laser fluorescence spectroscopy (TRLFS), luminescence and UV/Vis spectroscopy are applied. Information on the structure of M(III)-aq-BTP complex species is obtained from density functional theory. Three different M(III) complex species containing one, two or three aq-BTP ligands are identified in H 2 O at pH 3.0. Relative fluorescence intensity factors are determined for each of the [M(aq-BTP) n ] complexes (M = Cm(III)/Eu(III), n = 1 - 3). These factors are required to quantify the complexes. The stability constant logβ 3 of the [Cm(aq-BTP) 3 ] complex (which is the one relevant to extraction processes) is two orders of magnitude higher than that of the corresponding Eu(III) complex. This difference is in agreement with the separation factor (SF Am(III)/Eu(III) = 150) determined experimentally by liquid-liquid extraction. The difference in the stability constants originates from the different reaction enthalpies for the formation of the [M(aq-BTP) 3 ] complexes. These results represent the thermodynamic driving force for the aq-BTPs selectivity towards trivalent actinides over lanthanides. Comparing the stability constants of the [M(aq-BTP) n ] species (M = Cm(III)/Eu(III), n = 1 - 3) shows an increasing selectivity with increasing number of coordinated aq-BTP ligands. Hence, high selectivity is achieved if the f-element ions are fully coordinated by nine N-donor atoms (three aq-BTP ligands). A less

Nuclear fuel cycle-oriented actinides separation in China

Energy Technology Data Exchange (ETDEWEB)

Chen, Jing; He, Xihong; Wang, Jianchen [Tsinghua Univ., Beijing (China). Inst. of Nuclear and New Energy Technology

2014-04-01

In the last decades, the separation of actinides was widely and continuously studied in China. A few kinds of salt-free reductants to adjust Pu and Np valences have been investigated. N,N-dimethylhydroxylamine is a good reductant with high reduction rate constants for the co-reduction of Pu(IV) and Np(VI), and monomethylhydrazine is a simple compound for the individual reduction of Np(VI). Advanced PUREX based on Organic Reductants (APOR) was proposed. Trialkylphosphine oxide (TRPO) with a single functional group was found to possess strong affinity to tri-, tetra- and hexa-valent actinides. TRPO process has been first explored in China for actinides partitioning from high level waste and the good partitioning performance was demonstrated by the hot test. High extraction selectivity for trivalent actinides over lanthanides by dialkyldithiophosphinic acids was originally found in China. A separation process based on purified Cyanex 301 for the separation of Am from lanthanides was presented and successfully tested in a battery of miniature centrifugal contactors. (orig.)

Actinides in irradiated graphite of RBMK-1500 reactor

Energy Technology Data Exchange (ETDEWEB)

Plukienė, R., E-mail: rita@ar.fi.lt; Plukis, A.; Barkauskas, V.; Gudelis, A.; Gvozdaitė, R.; Duškesas, G.; Remeikis, V.

2014-10-01

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

Solubility of actinides and surrogates in nuclear glasses; Solubilite des actinides et de leurs simulants dans les verres nucleaires. Limites d'incorporation et comprehension des mecanismes

Energy Technology Data Exchange (ETDEWEB)

Lopez, Ch

2003-07-01

The nuclear wastes are currently incorporated in borosilicate glass matrices. The resulting glass must be perfectly homogeneous. The work discussed here is a study of actinide (thorium and plutonium) solubility in borosilicate glass, undertaken to assess the extent of actinide solubility in the glass and to understand the mechanisms controlling actinide solubilization. Glass specimens containing; actinide surrogates were used to prepare and optimize the fabrication of radioactive glass samples. These preliminary studies revealed that actinide Surrogates solubility in the glass was enhanced by controlling the processing temperature, the dissolution kinetic of the surrogate precursors, the glass composition and the oxidizing versus reducing conditions. The actinide solubility was investigated in the borosilicate glass. The evolution of thorium solubility in borosilicate glass was determined for temperatures ranging from 1200 deg C to 1400 deg C.Borosilicate glass specimens containing plutonium were fabricated. The experimental result showed that the plutonium solubility limit ranged from 1 to 2.5 wt% PuO{sub 2} at 1200 deg C. A structural approach based on the determination of the local structure around actinides and their surrogates by EXAFS spectroscopy was used to determine their structural role in the glass and the nature of their bonding with the vitreous network. This approach revealed a correlation between the length of these bonds and the solubility of the actinides and their surrogates. (author)

Self-interaction corrected local spin density calculations of actinides

DEFF Research Database (Denmark)

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 actinide ions in these compounds from first principles. Here we review a number of applications, ranging from electronic structure calculations of actinide metals, nitrides and carbides to the behaviour under pressure of intermetallics, and O vacancies in PuO2....

Separation and preconcentration of actinides from acidic media by extraction chromatography

International Nuclear Information System (INIS)

Horwitz, E. Philip; Chiarizia, Renato; Dietz, Mark L.; Diamond, Herbert; Nelson, Donald M.

1993-01-01

A systematic examination of the effect of nitric and hydrochloric acid concentrations and of macro levels of selected elements on the sorption of actinide ions by a novel extraction chromatographic resin comprised of a solution of octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide in tri-n-butyl phosphate supported on an inert polymeric substrate is described. Actinide sorption is demonstrated to be most efficient at high (>1 M) nitric acid concentrations, although tetra- and hexavalent actinides are strongly retained even from dilute (e.g., 0.05 M) nitric acid solutions. Macro concentrations of several common anions (e.g., PO 4 3- and SO 4 2- ) or complexing agents (e.g., oxalic acid) are shown not to adversely affect the sorption of trivalent actinides, while reducing the sorption of tetravalents. Such effects, together with oxidation state adjustments, are shown to provide a basis for the sequential elution of individual actinides and for actinide isolation from environmental and biological matrices

The electronic structure of the lanthanides and actinides, a comparison

International Nuclear Information System (INIS)

Edelstein, N.M.

1998-01-01

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

A spectroscopic screening of the chemical speciation of europium(III) in gastrointestinal tract. The intestine

Energy Technology Data Exchange (ETDEWEB)

Wilke, Claudia; Barkleit, Astrid [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Div. Chemistry of the F-Elements

2016-07-01

To evaluate the health risks of lanthanides (Ln) and radiotoxic actinides (An), investigations into the chemical reactions of these metals in the human gastrointestinal tract are necessary. In order to identify the dominant binding partners (i.e. counter ions and/or ligands) of An/Ln in the gastrointestinal tract, a spectroscopic screening was performed by Time-Resolved Laser-induced Fluorescence Spectroscopy (TRLFS) using artificial digestive juices containing Eu(III), a representative of Ln(III) and An(III). In the intestine, Eu(III) show a strong complexation especially with organic substances of the pancreatic and bile juice like the protein mucin.

Actinide distribution in the human skeleton

International Nuclear Information System (INIS)

Kathren, R.L.; McInroy, J.F.; Swint, M.J.

1985-05-01

Radiochemical analysis of two half skeletons donated to the United States Transuranium Registry, one from an individual with an occupationally incurred deposition of 241 Am and the other with a deposition of 239 Pu, revealed an inverse linear relationship between the concentration of actinide in the bone ash and the fraction of ash. Two distinct relationships were noted, one for the cranium and the other for the remainder of the skeleton. The results suggest that the actinide content of the skeleton as a whole, Q, can be obtained with an uncertainty of +-50% from analysis of a single sample of any bone (except the cranium) by Q = [(830 C/sub sample/)/(0.61 - f/sub sample/)], in which C/sub sample/ refers to the actinide content per g of ash and f/sub sample/ the fraction of ash (i.e., ratio of dry to wet weight) in the sample. 5 figs., 3 tabs

Mixer-settler performance evaluation in actinide extraction

International Nuclear Information System (INIS)

Camilo, R.L.; Goncalves, M.A.; Carvalho, E.I.; Nakazone, A.K.; Araujo, B.F. de; Araujo, J.A.

1988-07-01

This paper deals with four conceptions of mixer-settlers used for actinide purification and recovery. By means of the uranium concentration profiles in the organic and aqueous phases, the evaluation of each mixer-settler was made. The main purpose of this work is the data acquisition, for adapting the different contactor types to actinide recovery by liquid-liquid extraction, in the nuclear fuel cycle. (autor) [pt

New strategies for the chemical separation of actinides and lanthanides

International Nuclear Information System (INIS)

Hudson, M.J.; Iveson, P.B.

2002-01-01

A general model is proposed for the effective design of ligands for partitioning. There is no doubt that the correct design of a molecule is required for the effective separation by separation of metal ions such as lanthanides(III) and actinides(III). Heterocyclic ligands with aromatic rings systems have a rich chemistry, which is only now becoming sufficiently well understood, in relation to the partitioning process. The synthesis, characterisation and structures of some chosen molecules will be introduced in order to illustrate some important features. For example, the molecule N-butyl-2-amino-4,6-di (2-pyridyl)-1,3,5-triazine (BADPTZ), which is an effective solvent extraction reagent for actinides and lanthanides, has been synthesised, characterised and its interaction with metal ions studied. The interesting and important features of this molecule will be compared with those of other heterocyclic molecules such as 2,6-bis(5-butyl-1,2,4-triazol-3-yl) pyridine (DBTZP), which is a candidate molecule for the commercial separation of actinides and lanthanide elements. Primary Coordination Sphere. One of the most critical features concerning whether a molecule is a suitable extraction reagent is the nature of the binding and co-ordination in the primary co-ordination sphere. This effect will be considered in depth for the selected heterocylic molecules. It will be shown how the bonding of the heterocyclic and nitrate ligands changes as the complete lanthanide series is traversed from lanthanum to lutetium. For effective solvent extraction, the ligand(s) should be able completely to occupy the primary co-ordination sphere of the metal ion to be extracted. Interactions in the secondary co-ordination sphere are of less importance. Inter-complex Hydrogen Bonding Interactions. Another feature that will be considered is the intermolecular binding between ligands when bound to the metal ion. Thus the intermolecular structures between complex molecules will be considered

Synergistic extraction of actinides : Part I. Hexa-and pentavalent actinides

International Nuclear Information System (INIS)

Patil, S.K.; Ramakrishna, V.V.

1980-01-01

A detailed discussion on the reported literature on the synergistic extraction of hexa- and pentavalent actinide ions, by different combinations of extractants and from different aqueous media, is presented. Structural aspects of the various complexes involved in synergism also are reviewed. A short account of the applications based on synergistic extraction is also given. (author)

ACTINET: a European Network for Actinide Sciences

International Nuclear Information System (INIS)

Bernard Boullis; Pascal Chaix

2006-01-01

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

Adventures in Actinide Chemistry: A Year of Exploring Uranium and Thorium in Los Alamos

Energy Technology Data Exchange (ETDEWEB)

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.

Preliminary considerations concerning actinide solubilities

International Nuclear Information System (INIS)

Newton, T.W.; Bayhurst, B.P.; Daniels, W.R.; Erdal, B.R.; Ogard, A.E.

1980-01-01

Work at the Los Alamos Scientific Laboratory on the fundamental solution chemistry of the actinides has thus far been confined to preliminary considerations of the problems involved in developing an understanding of the precipitation and dissolution behavior of actinide compounds under environmental conditions. Attempts have been made to calculate solubility as a function of Eh and pH using the appropriate thermodynamic data; results have been presented in terms of contour maps showing lines of constant solubility as a function of Eh and pH. Possible methods of control of the redox potential of rock-groundwater systems by the use of Eh buffers (redox couples) is presented

Orbital effects in actinide systems

International Nuclear Information System (INIS)

Lander, G.H.

1983-01-01

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

Complexation of biological ligands with lanthanides(III) for MRI: Structure, thermodynamic and methods; Complexation des cations lanthanides trivalents par des ligands d'origine biologique pour l'IRM: Structure, thermodynamique et methodes

Energy Technology Data Exchange (ETDEWEB)

Bonnet, C

2006-07-15

New cyclic ligands derived from sugars and amino-acids form a scaffold carrying a coordination sphere of oxygen atoms suitable to complex Ln(III) ions. In spite of their rather low molecular weights, the complexes display surprisingly high relaxivity values, especially at high field. The ACX and BCX ligands, which are acidic derivatives of modified and cyclo-dextrins, form mono and bimetallic complexes with Ln(III). The LnACX and LnBCX complexes show affinities towards Ln(III) similar to those of tri-acidic ligands. In the bimetallic Lu2ACX complex, the cations are deeply embedded in the cavity of the ligand, as shown by the X-ray structure. In aqueous solution, the number of water molecules coordinated to the cation in the LnACX complex depends on the nature and concentration of the alkali ions of the supporting electrolyte, as shown by luminescence and relaxometric measurements. There is only one water molecule coordinated in the LnBCX complex, which enables us to highlight an important second sphere contribution to relaxivity. The NMR study of the RAFT peptidic ligand shows the complexation of Ln(III), with an affinity similar to those of natural ligands derived from calmodulin. The relaxometric study also shows an important second sphere contribution to relaxivity. To better understand the intricate molecular factors affecting relaxivity, we developed new relaxometric methods based on probe solutes. These methods allow us to determine the charge of the complex, weak affinity constants, trans-metallation constants, and the electronic relaxation rate. (author)

Formation of actinides in irradiated HTGR fuel elements

International Nuclear Information System (INIS)

Santos, A.M. dos.

1976-03-01

Actinide nuclide concentrations of 11 spent AVR fuel elements were determined experimentally. The burnup of the spheres varied in the range between 10% and 100% fifa, the Th : U ratio was 5 : 1. The separation procedures for actinide isolation were tested with highly irradiated ThO 2 . Separation and decontamination factors are presented. Actinide nuclide formation can be described by exponential functions of the type ln msub(nuclide) = A + B x % fifa. The empirical factors A and B were calculated performing a least squares analysis. Build-up of 232 U was discussed. According to the experimental results, 232 U is mainly produced from 230 Th, a certain amount (e.g. about 20% at a 10 5 MWd/t burnup) originated from a (n,2n) reaction of 233 U; a formation from 233 Th by a (n,2n) followed by a (n,γ) reaction was not observed. The AVR breeding rate was ascertained to be 0.5. The hazard potential of high activity waste was calculated. After a 1,000 years' storage time, the elements Pa, Am and Cm will no longer influence the total hazard index. Actinide recovery factors were proposed in order to reduce the hazard potential of the waste by an actinide removal in consideration of the reprocessing technology which is available presently. (orig.) [de

Room temperature electrodeposition of actinides from ionic solutions

Science.gov (United States)

Hatchett, David W.; Czerwinski, Kenneth R.; Droessler, Janelle; Kinyanjui, John

2017-04-25

Uranic and transuranic metals and metal oxides are first dissolved in ozone compositions. The resulting solution in ozone can be further dissolved in ionic liquids to form a second solution. The metals in the second solution are then electrochemically deposited from the second solutions as room temperature ionic liquid (RTIL), tri-methyl-n-butyl ammonium n-bis(trifluoromethansulfonylimide) [Me.sub.3N.sup.nBu][TFSI] providing an alternative non-aqueous system for the extraction and reclamation of actinides from reprocessed fuel materials. Deposition of U metal is achieved using TFSI complexes of U(III) and U(IV) containing the anion common to the RTIL. TFSI complexes of uranium were produced to ensure solubility of the species in the ionic liquid. The methods provide a first measure of the thermodynamic properties of U metal deposition using Uranium complexes with different oxidation states from RTIL solution at room temperature.

Technical requirements for the actinide source-term waste test program

Energy Technology Data Exchange (ETDEWEB)

Phillips, M.L.F.; Molecke, M.A.

1993-10-01

This document defines the technical requirements for a test program designed to measure time-dependent concentrations of actinide elements from contact-handled transuranic (CH TRU) waste immersed in brines similar to those found in the underground workings of the Waste Isolation Pilot Plant (WIPP). This test program wig determine the influences of TRU waste constituents on the concentrations of dissolved and suspended actinides relevant to the performance of the WIPP. These influences (which include pH, Eh, complexing agents, sorbent phases, and colloidal particles) can affect solubilities and colloidal mobilization of actinides. The test concept involves fully inundating several TRU waste types with simulated WIPP brines in sealed containers and monitoring the concentrations of actinide species in the leachate as a function of time. The results from this program will be used to test numeric models of actinide concentrations derived from laboratory studies. The model is required for WIPP performance assessment with respect to the Environmental Protection Agency`s 40 CFR Part 191B.

Technical requirements for the actinide source-term waste test program

International Nuclear Information System (INIS)

Phillips, M.L.F.; Molecke, M.A.

1993-10-01

This document defines the technical requirements for a test program designed to measure time-dependent concentrations of actinide elements from contact-handled transuranic (CH TRU) waste immersed in brines similar to those found in the underground workings of the Waste Isolation Pilot Plant (WIPP). This test program wig determine the influences of TRU waste constituents on the concentrations of dissolved and suspended actinides relevant to the performance of the WIPP. These influences (which include pH, Eh, complexing agents, sorbent phases, and colloidal particles) can affect solubilities and colloidal mobilization of actinides. The test concept involves fully inundating several TRU waste types with simulated WIPP brines in sealed containers and monitoring the concentrations of actinide species in the leachate as a function of time. The results from this program will be used to test numeric models of actinide concentrations derived from laboratory studies. The model is required for WIPP performance assessment with respect to the Environmental Protection Agency's 40 CFR Part 191B

Actinide production in 136Xe bombardments of 249Cf

International Nuclear Information System (INIS)

Gregorich, K.E.

1985-08-01

The production cross sections for the actinide products from 136 Xe bombardments of 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 136 Xe + 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 136 Xe + 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

Preparation, properties, and some recent studies of the actinide metals

International Nuclear Information System (INIS)

Haire, R.G.

1985-01-01

The actinide elements form a unique series of metals. The variation in their physial properties combined with the varying availability of the different elements offers a challenge to the preparative scientist. This article provides a brief review of selected methods used for preparing μg to kg amounts of the actinide metals and the properties of these metals. In addition, some recent studies on selected actinide metals are discussed. 62 refs

Complexation studies of actinides (U, Pu, Am) with linear polyamino-carboxylate ligands and sidero-chelates; Etudes de la chelation d'actinides (U, Pu, Am) par des ligands polyaminocarboxylate lineaires et des siderochelates d'interet environnemental

Energy Technology Data Exchange (ETDEWEB)

Nguyen, L.V.

2010-11-25

As part of our research endeavour aimed at developing and improving decontamination processes of wastewater containing alpha emitters, physico-chemical complexation studies of actinides (U, Pu, Am) with organic open-chain ligands such as poly-aminocarboxylic acids (H{sub 4}EDTA) and sidero-chelates (di-hydroxamic acids and desferrioxamine B) have been carried out. Gaining a clear understanding of the coordination properties of the targeted actinides is an essential step towards the selection of the most appropriate chelating agents that will exhibit high uptake efficiencies. EXAFS (Extended X-ray Absorption Fine Structure) measurements at the ESRF synchrotron enabled to elucidate the coordination scheme of uranium and plutonium complexes. Solution thermodynamic investigations were intended to provide valuable information about the nature and the stability of the uranium(VI) and americium(III) complexes prevailing at a given pH in solution. The set of stability constants determined from potentiometric and UV-visible spectrophotometric titrations, allowed to predict the speciation of the selected actinides in presence of the aforementioned ligands and to determine the pH range required for achieving 'ultimate' decontamination. (author) [French] Dans le cadre du developpement et de l'amelioration des procedes de decontamination d'effluents aqueux contamines par des radioelements emetteurs alpha, des etudes physico-chimiques sur la complexation des actinides (U, Pu, Am) avec des ligands organiques tels que des acides polyaminocarboxyliques lineaires (H{sub 4}EDTA) et des siderochelates (acides dihydroxamiques et desferrioxamine B) ont ete effectuees. La comprehension des proprietes de coordination est une etape essentielle pour selectionner les meilleurs agents chelatants qui se montreront efficaces dans le traitement des effluents. Les schemas de coordination des complexes d'uranium et de plutonium avec ces ligands ont ete determines a l

New solvent extraction processes for minor actinides: CIEMAT contribution to the partnew project: EU contract n. FIKW-CT2000-0087: first semestral period 2001 september 2000-february 2001

International Nuclear Information System (INIS)

2002-01-01

This report includes the work developed at CIEMAT into the partnew project: '' New solvent extraction processes for minor actinides, during the first semestral period (september 2000 to february 2001), CIEMAT is involved in the following task: the study of the actinides (AN) and lanthanides (LN) extracting properties of new compounds with chemical structure based on two malonamide groups linked to an aromatic platform. The study of new-bearing extractants with chemical structure similar to malonamides aforementioned, changing the 0 atoms by s atoms, and the determination of the selectivity of these new thiomalonamides for AN(III) extraction. (Author)

Complex formation of americium (III) with humic acid

International Nuclear Information System (INIS)

Zhang Yingjie; Zhao Xin; Wen Liansheng; Lin Zhangji

2004-01-01

The presence of humic substances in natural waters will modify the migration behavior of actinides in the geosphere due to the strong reaction properties of these ligands with actinides. Therefore, the possible reactions of humic acid with actinides have been studied widely in recent years. The complex formation of Am (III) with humic acid is studied with solvent extraction technique in this paper. The experiments are performed in the pH range from 4.0 to 8.0 in 0.1 M NaClO 4 solution at ambient temperature. Experimental results show that the complex formation constants of Am (III) with humic acid are varied with the variation of pH value in solution. 1:2 complex is obtained in the experiments and the complex formation constants determined at each pH are: lgβ 1 =6.56±0.05, lgβ 2 =10.77±0.31 at pH=4.0; lgβ 1 =7.94±0.11, lgβ 2 =11.80±0.21 at pH=5.0; lgβ 1 =10.74±0.28, lgβ 2 =12.88±0.49 at pH=6.0; lgβ 1 =12.85±0.30, lgβ 2 =14.80±0.62 at pH=7.0; lgβ 1 =14.88±0.48, lgβ 2 =15.65±0.69 at pH=8.0, respectively. The dependence of the complex of the complex formation constant on pH is: lgβ 1 =2.16(±0.98)pH-2.34(±1.03), lgβ 2 =1.28(±1.04)pH+5.52(±1.21), respectively. (author)

Rapid Separation Methods to Characterize Actinides and Metallic Impurities in Plutonium Scrap Materials at SRS

International Nuclear Information System (INIS)

Maxwell, S.L. III; Jones, V.D.

1998-07-01

The Nuclear Materials Stabilization and Storage Division at SRS plans to stabilize selected plutonium scrap residue materials for long term storage by dissolution processing and plans to stabilize other plutonium vault materials via high-temperature furnace processing. To support these nuclear material stabilization activities, the SRS Analytical Laboratories Department (ALD) will provide characterization of materials required prior to the dissolution or the high-firing of these materials. Lab renovations to install new analytical instrumentation are underway to support these activities that include glove boxes with simulated-process dissolution and high- pressure microwave dissolution capability. Inductively-coupled plasma atomic emission spectrometry (ICP-AES), inductively- coupled mass spectrometry (ICP-MS) and thermal-ionization mass spectrometry (TIMS) will be used to measure actinide isotopics and metallic impurities. New high-speed actinide separation methods have been developed that will be applied to isotopic characterization of nuclear materials by TIMS and ICP-MS to eliminate isobaric interferences between Pu-238 /U- 238 and Pu-241/Am-241. TEVA Resin, UTEVA Resin, and TRU Resin columns will be used with vacuum-assisted flow rates to minimize TIMS and ICP-MS sample turnaround times. For metallic impurity analysis, rapid column removal methods using UTEVA Resin, AGMP-1 anion resin and AG MP-50 cation resin have also been developed to remove plutonium and uranium matrix interferences prior to ICP-AES and ICP- MS measurements