«XVIII ÌÅÍÄÅËÅÅÂÑÊÈÉ ÑÚÅÇÄ ÏÎ ÎÁÙÅÉ È ÏÐÈÊËÀÄÍÎÉ ÕÈÌÈÈ Ìîñêâà, 23–28 ñåíòÿáðÿ 2007 ã. ÒÅÇÈÑÛ ÄÎÊËÀÄÎÂ Ìîñêâà – 2007 ÓÄÊ ...»
It is recommended after shutdown to continue the coolant circulation during 2 – 5 days for total coolant activity decreasing1. Usually the anion-exchange resins are used for decreasing of radioac tive iodine in the coolant at NPPs. Because of anion-exchange resins are capable to absorb only ionic forms of radioactive iodine, for prevention of I2 accumulation in the coolant it is necessary or to support constantly coolant pH is not lower 9.0, or to use the materials locating I2 from it. Use of such materials during shutdown will allow not only to decrease activity of the coolant, but also will sharply decrease emission of radioactive iodine in a gas phase. For this purpose it is desirable to use materials which are applied on the working NPPs to clearing coolant, for example ion-exchange resins.
In the Institute of Physical Chemistry and Electrochemistry of the Russian Academy of Science as a result on modifying of KU-2 cation-exchange resin the new materials was developed. These materials are capable to absorb 131I2 from a solution corresponding the coolant of the Russian WWER NPPs with factors of distribution more than 103 ml/g. It is established, that practically full I2 absorption is achieved for 15 min.
In summary, it is necessary to note, that use of the developed materials will not demand to change designs of NPPs and to bring essential changes in sites of coolant clearing. At the same time, the given materials will allow not only to decrease the content of radioactive iodine in the coolant, but also to reduce emissions of radioactive iodine in working rooms of NPPs, i.e. to de crease loading on the iodine filters during shutdown and an overload of the irradiated fuel.
References 1. Kritskii V.G., Rodionov Yu.A., Ampelogova N.I. "Behaviour of radioactive iodine isotopes in a contour of repeated compulsory circulation at RBMK" // Atomnaya Energiya (Russia). 2005. V. 99, no 2. P. 103 – 108.
2508 ÕVIII Ìåíäåëååâñêèé ñúåçä ïî îáùåé è ïðèêëàäíîé õèìèè, Ìîñêâà, BOROPHOSPHATE GLASSES FOR IMMOBILIZATION OF RADIOACTIVE WASTES Kuznetsov D.G., Ivanov V.V., Ershov B.G., Minaev A.A., Popov I.B.
A.N. Frumkin”s Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, Russia, Lenynsky prosp. 31, k. e-mail: email@example.com The immobilization of the radioactive wastes is important problem for atomic engineering and ra diochemical industry. Without its solution the further development of the atomic industry is impos sible. A number of the serious requirements are produced to materials for the immobilization and processes of them manufacturing: high chemical, mechanical, thermal and radiation stability. So dium-alumo-phosphate glass has the good cooking properties – they low melts, well flowed out at rather low temperature. Sodium-alumo-phosphate glassy system was investigated for the purposes of solidification of the radioactive waste. This system has a number of advantages before others – including: the capability of liquid fluxing of glass formation agent, lower temperature of cooking, capability of including of the significant amounts of different macro elements containing in waste.
These properties can supply the high efficiency of smelting equipment. Sodium-alumo-phosphate glass has high chemical stability in water in the optimal interval of compositions. Their leaching rate in water is ~10-5 –10-6g/cm2 day. The introducing of the boric anhydride does not increase the leaching rate of glasses. Under the data of PA “MAYAK” the composition of HLW is simulated and the glass formation in ultra phosphate area of the system Na2O-P2O5-SiO2-B2O3 (“model HLW”) is investigated at temperatures from 1000 up to 12000C. The composition steadily forming glasses are detected at different concentrations of the B2O3 and SiO2 additions.
The work has been carried out with financial support of ISTC (Project #2252).
ÕVIII Ìåíäåëååâñêèé ñúåçä ïî îáùåé è ïðèêëàäíîé õèìèè, Ìîñêâà, 2007 RESEARCH OF BOROSILICATE MATRIXES FOR IMMOBILIZATION OF RADIOACTIVE WASTES Kuznetsov D.G., Minaev A.A., Ershov B.G., Popov I.B., Ivanov V.V.
A.N. Frumkin”s Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, Russia, Lenynsky prosp. 31, k. e-mail: firstname.lastname@example.org The concept of fractionation of the radioactive wastes has been accepted in many countries. The idea consists in isolation of the most environmentally hazardous long-lived -active actinides, REE, cesium/strontium fractions, etc. Material used for RW immobilization should possess high thermal and radiation stability, mechanical strength, and low water solubility rate. Glassy matrixes of na trium – phosphate, natrium – fluorine-phosphate, natrium – boron-phosphate and natrium – boron – fluorine – phosphate matrix, and also different silica-alumina and lead-silicate compositions with a number of the additions have been investigated. As the effective additives were used: PbO, NaF, B2O3, Fe2O3, NaPO3, CaO, Na2O, CeO2 in quantity 5 – 20% wt. It has been shown that the concen tration of the boric anhydride about 15% wt. for boron-silicate systems is optimal from the point of view of the ratio of synthesizing temperature and chemical stability. The leaching rate of obtained glassy matrixes lies within the limits 10-6-5·10-7 g/cm2 day. The replacement of SiO2 and Al2O3 by stone casting (SC) improves the characteristics of the system, as in the case of cesium systems. The investigations presented in this work provide the conclusion that sodium-lead-silicate and boron basalt systems are most appropriate for the immobilization of the Cs – Sr fraction of RAW. The SC B2O3-SrO system provides practically the maximum chemical stability. On the basis of the investi gations, presented in this work, it is possible to make a conclusion, that the most reasonable for the purposes of the immobilization of Cs – Sr fraction of RAW are sodium-lead-silicate and boron basalt system.
The work has been carried out with financial support of ISTC (Project #2252).
2510 ÕVIII Ìåíäåëååâñêèé ñúåçä ïî îáùåé è ïðèêëàäíîé õèìèè, Ìîñêâà, RADIATION DAMAGES IN CRYSTALLINE ACTINIDE HOST PHASES Laverov N.P.a, Yudintsev S.V.a, Lukinykh A.N.b, Stefanovsky S.V.c, Livshits T.S.a a IGEM RAS, Staromonetny lane 35, Moscow 119017 Russia b FSUE SRC RF Institute of Nuclear Reactors, Dimitrovgrad-10, Ulyanovsk reg. 433510 Russia c SUE SIA Radon, 7th Rostovskii lane 2/14, Moscow 119121 Russia Immobilization of actinide wastes generated in nuclear fuel cycle in stable crystalline matrices to be disposed in underground repositories is an effective method of their long-term storage. Reliability of this method is confirmed by a high resistance of naturally-occurred radioactive minerals with age of up to hundreds of millions years. Based on the results of their study a number of synthetic phases capable to retain actinides strongly in crystal lattice have been proposed. Disordering of the struc ture of the actinide host phases will inevitably occur in time due to actinide decay that may affect their isolation properties.
To study alteration of the actinide host phases due to irradiation three techniques are applied:
study of naturally-occurred radioactive minerals – analogues;
ion-bombardment of synthetic phases with accelerated ions;
incorporation of short-lived actinides (238Pu, 244Cm) in the structure of the phases. The latter two are major techniques to study radiation resistance of the compounds not hav ing naturally-occurred analogues.
Cubic oxides with murataite and garnet type structure are considered as promising actinide host phases1,2. These phases doped with 244Cm have been established to be rendered amorphous at a dose of (1.6-2.4)1018 -decays/g or about 0.2 dpa. These data are consistent with values obtained at ir radiation of the same matrices with krypton ions1–4.
Radiation resistance of synthetic actinide-loaded phases and their natural analogues was com pared. The irradiation doses required to destroy synthetic phases were found to be lower than the values for radioactive minerals5,6. This is due to recovery of radiation damaged structure of the minerals with time. Heat-treatment of the amorphized samples recovers initial crystal structure.
Amorphization leads to slight reduction in durability of the phases to aqueous solutions – acti nide leach rates increase by no more than 5 times as compared with the initial samples.
The work was performed under support of the Russian Foundation for Basic Research (project 05-05-64005).
References 1. N.P. Laverov, S.V. Yudintsev, T.S. Yudintseva et al., Geol. Ore Deposits 2003, 45, 423.
2. N.P. Laverov, S.V. Yudintsev, S.V. Stefanovsky et al., Geol. Ore Deposits 2006, 48, 387.
3. S. Utsunomiya, S. Yudintsev, R. Ewing, J. Nucl. Materials 2005, 336, 251.
4. J. Lian, L. Wang, R. Ewing, S. Yudintsev, S. Stefanovsky, J. Appl. Physics 2005, 97, 5. S. Utsunomiya, S. Yudintsev, L. Wang, R. Ewing, J. Nucl. Materials 2003, 322, 180.
6. T.S. Livshits, Geol. Ore Deposits 2006, 48, 410.
ÕVIII Ìåíäåëååâñêèé ñúåçä ïî îáùåé è ïðèêëàäíîé õèìèè, Ìîñêâà, 2007 NEW SORBENTS FOR EXTRACTION OF CESIUM AND STRONTIUM RADIO NUCLIDES AND TOXIC METALS FROM THE LIQUID WASTES Levchenko L.M.a, Mitkin V.N.ab a Nikolaev Institute of Inorganic Chemistry SB RAS, 3, Acad. Lavrentiev Avenue, Novosibirsk, 630090,RUSSIA, e-mail email@example.com b Joint Stock Novosibirsk Chemical Concentrates Plant Inc., 94, Bogdan Khmelnitsky str., Novosibirsk, 630110,RUSSIA One of the most relevant problems of a modern industry is the neutralization of liquid radioactive wastage (LRW), and also liquid wastes, containing toxic metals (Hg, Pb, Ni etc.) in linkages with their high danger to ecosystems. The modern technologies of neutralization of LRW and drains are commonly based on combinations of various processes of the toxic metals concentrating in a mini mal sizes of condensed phases with the purpose of their subsequent burial place, and the best results are reached with application of sorption methods.
At the present R&D the variants of sorption technologies of extraction of toxic metals, Cs and Sr radio nuclides are developed and discussed. There are considered a most perspective nanocomposi tion “carbon-carbon” and “carbon-fluorocarbon” matrices NUMS-O, FS-OH, FUCM-OH and im pregnated sorbents on their base. It has been shown that immobilization of an amorphous and crys talline antimonic(V) acid on the carboniferous nanocomposition matrices has allowed to create a new types of sorbents, selective for extraction of alkali and alkali earth metals from water solutions (including LiOH and LiCl industrial solutions).
On the base of FTIR and Raman spectroscopy datas and also with diffraction study it was exhib ited, that the fixing of an antimonic(V) acid on a surface of mezo- and micropores of carbon matri ces is realized by interaction of functional surface groups sp3-C-OH, sp2-COO– with Sb-O or Sb OH-bonds of antimonic(V) acid, and an intensity of this interaction depends on temperature. There is offered a concept of mechanism of antimony(V) oxides fixation on the carboniferous matrices, based on the formation of oxide Sb(V) nanolayers, connected with a matrix surface by bridge bonds C-O-Sb.
There are studied the processes of cesium and strontium sorption from model solutions CsCl and SrCl2 (0.5 – 2000 mg/l) in static and dynamic conditions. The static capacitances of nanocomposi tion sorbents are defined. It was shown that the sorption Cs and Sr from water solutions on the hy drophilised fluorocarbon and on an oxidized carbon surface proceeds via chemisorption’s mecha nism.
With application of chemical modification and fixing of Sb(V) oxides onto the “carbon – car bon” and the “carbon – fluorocarbon” matrices is set up a new generation of sorbents NUMS-1, NUMS-2, NUMS-RS, NUMS-O, FS-RS and FUCM-RS, selective on Hg, Ni, Cs and Sr, perspec tive for toxic metals extraction from liquid wastes and deactivation of LRW.
The modification of the carboniferous matrix surfaces is increased their sorption ability, provides selectivity to the preselected components, characterizes by uniformity and allows to produce a nec essary sorbents for extraction of mercury, Cs and Sr radio nuclides, and also heavy metals from liq uid industrial wastes. The introduction of fluorocarbon into sorbent’s matrices allows sharply to rise their stability to oxidizing conditions.
The researches were fulfilled at the financial support of JS Novosibirsk Chemical Concentrates Plant Inc. and by the State Contract ¹ 02.434.11. 2512 ÕVIII Ìåíäåëååâñêèé ñúåçä ïî îáùåé è ïðèêëàäíîé õèìèè, Ìîñêâà, CORROSION BEHAVIOR OF THE REE-ACTINIDE GARNET BASED WASTE FORMS IN WATER SOLUTIONS Livshits T.S.a, Chae S.C.b a IGEM RAS, Staromonetny lane 35, 119017 Moscow, Russia b KIGAM, Kajung-Dong 30, 305-350 Taejon, Republic of Korea Ferrites with garnet structure (Ia3d) and stoichiometry (Ca,REE,An)(Zr,Fe)2Fe3O12 are considered as promising actinide waste forms.
Fig. 1. Leaching rate of Ce from sample G25 (left) and Gd from G25 and G21 (right) in various solutions.
The study was supported by the Russian Foundation for Basic Research (project 05-05-64005).
References 1. T.S. Yudintseva, Geol. of Ore Deposits 2005, 47, 444.
2. S. Yudintsev, A. Osherova, A. Dubinin et al., MRS Symp. Proceedings 2004, 824, 287.
ÕVIII Ìåíäåëååâñêèé ñúåçä ïî îáùåé è ïðèêëàäíîé õèìèè, Ìîñêâà, 2007 CONTROL OF TECHNOGENIC RADIONUCLIDES CONTENT IN ENVIRONMENTAL OBJECTS OF MEGALOPOLIS Marennyy A.M., Astafurov V.I., Marennyy M.A.
Group REI, JSC “Radiation and Ecology Investigations”, 123182 Moscow, Schukinskaya st., 40 e-mail firstname.lastname@example.org Wide application of radioactive isotopes and cases of uncontrolled management of active waste, particularly in the past, stimulate the need for reliable control of technogenic radionuclides content in environmental objects of megalopolis.
The largest number of revealed radioactive contaminations is exhibited in on areas allotted for novel buildings and areas intended for recreation purposes. Ecologic surveys of such areas rather often reveal non-sanctioned dumps of garbage also containing industrial waste with encountered local sources and zones of radioactive contamination of different nature. Intensity and radionuclide composition of contaminations might be quite different. In compliance with the effective standard documents all radioactive contaminations have to be found out, classified and removed from area before using it. As far as gamma-irradiating nuclide contaminations it is not difficult to reveal and classify them, they are subject to routine analysis. To determine beta- and alpha-radiating nuclides is, as a rule, a laborious and expensive analytic operation. This circumstance dictates specific re quirements for procedures of analytic control of technogenic radionuclides, the principal ones of them being selectivity and expressness.
The paper presents the results of development and application of a complex of analytic control procedures used to determine the content of technogenic radionuclides in environmental objects of megalopolis as applied to Moscow conditions, compares various methodological approaches to in vestigating radionuclide contents;
specific features of sampling are reviewed in inspecting large ter ritories and places of waste storing. In particular, the authors designed selective and highly sensitive procedures of radiochemical determination of technecium, uranium, neptunium, plutonium, ameri cium and curium in water, soil, bottom deposits, aerosols, ashes of plants as well as procedures of irradiation control of territory allotted for building, determination of volume alpha-activity of air, specific alpha- and beta-activities of solid waste and scrap metal, nuclide composition of radioac tive contamination of aerosols and materials.
To concentrate, separate and decontaminate determined radionuclides use is made of co precipitation, extraction and extraction chromatography methods. The latter method uses as extrac tants methyltrioctylammonium nitrate, trioctylphosphineoxide and di(2-ethylhexyl)phosphoric acid that are contained in matrix of co-polymer styrene with divinylbenzene (“solid extractants”) or coat ing surface of heat treated large-pore fluoroplastic-4. As alternative extractants allyltrialkylammo nium nitrate and butylisooctyloximethylene phosphonic acid are used.
Separated radionuclides are measured by methods of alpha- and beta-counting, alpha-, beta- and gamma-spectrometry.
2514 ÕVIII Ìåíäåëååâñêèé ñúåçä ïî îáùåé è ïðèêëàäíîé õèìèè, Ìîñêâà, URANIUM CARBIDE OXIDATION WITH NITRIOUS ACID IN ACID SOLUTIONS Maslennikov A.G.a, Moisy Ph.b, Vermeulen J.b, Genin X.b, Astier N.b a A.N. Frumkin Institute of Physical Chemistry and Electrochemistry RAS, 31, Leninsky prospect, 119991, Moscow Russian Federation b Centre de Recherche «VALRHO» Commisariat l’Energie Atomique, BP 17171, 30207 Bagnols sur Cze, France Uranium monocarbide (UC) and mixed (U,Pu)C carbides may be used as a fissile material of triso fuel in the reactors of the IVth generation. The development of the aqueous techniques for the car bide fuel reprocessing a special attention is paid to the achievement of the actinide recovery close to 100% at all steps of the process, including the fuel dissolution. The present investigation is an at tempt of the fundamental study of the UC dissolution kinetics and dissolution products in the solu tions HClO4 and HNO3.
In the solutions 0,5-6,0 M HClO4 UC dissolution was shown to be ineffective (U(VI) yield did not exceed 2,0%). Nitrous acid was chosen as an oxidizing agent providing the oxidation potentials exceeding 400 mV / SCE in the solutions HClO4. The increase of HNO2 concentration to 0,1 M re sulted in the increase of UC dissolution yield to the values 95%. The decrease of HNO2 concentra tion during UC dissolution could be described with 1sr order equation if its initial concentration was greater than 0.05 M.
In the solutions HNO3 4.0 M the UC dissolution was preceded by the induction period. Its du ration decreased with the increase of HNO3 concentration. During induction period the increase of HNO2 concentration was observed. When HNO2 concentration exceeded 0,005 M, the UC dissolu tion accelerated rapidly. 100% U(VI) yield during UC dissolution in 3,0-6,0 mol·L–1 HNO3 at a room temperature was achieved in 30-40 min. HNO2 concentration during UC oxidation increased rapidly in first 20 min to 0,02-0,2 M varying as a function of HNO3 concentration and initial S/L ratio and then decreased due to disproportionation reaction.
The kinetic model, describing UC oxidation in the solutions HClO4 and HNO3 and taking into account the contribution of UC reactions with the ions H+, NO3- and HNO2 into the total value of the dissolution rate was proposed. The effective dissolution rate constants and reaction orders for the UC oxidation with the mentioned oxidizing agents in 0,5 – 6,0 mol·L–1 HClO4 were calculated.
The rate of UC oxidation with HNO2 was shown to exceed 100 times the oxidation rates with H+ and NO3- ions.
UC oxidation with nitrous acid in 0,5 – 6,0 M HClO4 was shown to result in 60-85% carbon oxi dation to CO2. The residuary carbon was distributed between dissolver solution and insoluble resi due. C/U(VI) ratio in the dissolver solution decreased from 0,5 to 0,1 mg-eq/mol with the increase of HClO4 and HNO2 in the solution. At the same time the increase of C/U(VI) ratio in the insoluble residue from 3,0 to 15.0 was observed. In the dissolver solutions HNO3 2,0 – 5,0% carbon remained in the insoluble residue even when 100% U(VI) yield was observed. According to the data of scan ning electron microscopy of insoluble residue the carbon particle size was varying from 1.0 to 5. m. The measurements of IR spectra of the insoluble residue indicated the presence of –COOH and –OH groups.
ÕVIII Ìåíäåëååâñêèé ñúåçä ïî îáùåé è ïðèêëàäíîé õèìèè, Ìîñêâà, 2007 APPLICATION OF IONIC LIQUIDS FOR ACTINIDE RECOVERY FROM NITRIC ACID SOLUTIONS BY EXTRACTION AND SORPTION METHODS Molochnikova N.P., Pribylova G.A., Zakharchenko E.A., Myasoedova G.V.
V.I.Vernadsky Institute of Geochemistry and Analytical Chemistry, Moscow, Kosygin St, 19, email@example.com The great interest to ionic liquids is stipulated by their special physical and chemical properties: low melting temperature, hydrophobity, ionic character, etc. Application of ionic liquids which possess of small volatility and weak toxicity, instead of traditional organic solvents is perspective for ex traction of different ions and organic compounds from water solution. It was shown earlier that dis tribution coefficients of metal ions (actinides for example) may to be increased when ionic liquids of imidazolium type were added to extractant. The possibility of ionic liquids to keep on various solid supports due to hydrophobic and other interactions allows to apply ionic liquids for obtaining of sorption materials for metal ions recovery from solutions.
In this work we have studied the possibility of application of imidazolium and phosphonium type ionic liquids with various anions for actinide recovery from nitric acid solutions by extraction and sorption methods. Ionic liquids of phosphonium type have not been applied earlier for actinides ex traction. At the same time phosphonium ionic liquids are characterized with higher chemical and radiation stability in comparison with imidazolium ionic liquids. That is very important for their application in nitric acid solutions.
We have investigated extraction of actinide complexes with diphenyldibutylcarbamoylmethyl phosphin oxide from 3M nitric acid solution in dichloroethane contained ionic liquids. It was dem onstrated that in case if content of ionic liquids was 1-50 mass%, americium distribution coeffi cients were increased in 5-60 times (phosphonium type ionic liquid) or in 25-125 times (imida zolium type ionic liquid).
We have synthesized the sorption materials for actinides recovery from nitric acid solutions by fixing of ionic liquids and organophosphorus ligands in ionic liquids on different polymeric ma trixes, including fiber. Investigation of actinide sorption has been shown that the sorbents impreg nated by phosphonium ionic liquids can be used for actinide recovery in 0.5- 5M HNO3. These sor bents contain 0.1-0.2 g of ionic liquid per gram of solid phase. The distribution coefficients of plu tonium in 3M HNO3 are (1.6-1.7)103 mL/g. The obtained sorbents are characterized with high effi ciency of actinides recovery, good kinetic properties, stability in nitric acid solutions, possibility of regeneration and reuse.
The experimental data have shown that application of ionic liquids essentially expands possibili ties of exraction and sorption methods for plutonium, americium and other radionuclides recovery.
It allows to increase the efficiency of actinide extraction and to obtain perspective sorption materials for actinides recovery from nitric acid solutions.
The authors want to thank Russian Foundation for Basic Research for financial support (grant 05-03-33094) 2516 ÕVIII Ìåíäåëååâñêèé ñúåçä ïî îáùåé è ïðèêëàäíîé õèìèè, Ìîñêâà, ESTIMATION OF THE OPPORTUNITY OF THE NON-AQUEOUS LEACHING AND SEPARATION OF REE AND THORIUM FROM THE FUSION OF CHLORIDES OF SOLIKAMSK MAGNESIAN FACTORY Murinov Yu.I., Danilov V.T., Kolyadina O.A.
Institute of Organic Chemistry Ufa Scientific Center RAS At pyro- and hydrometallurgical processing of ores a plenty of semiproducts which contain com pounds of rare earth, alkaline and alkali earth elements, and also natural compounds of thorium, uranium, products of their radioactive disintegration which are undesirable impurity is formed and complicate processing these concentrates. Plenties of the corrosion-active sewage containing radio active compounds formed at it, demand additional expenses for their purification. Therefore other receptions and the methods are necessary allowing not only selectively and with small losses to iso late REE, but also to lead purification of radioactive elements with the purpose of their convenient recycling.
With the purpose of elimination of the lacks inherent in hydrometallurgical repartition, we offer and investigate process of a non-aqueous leaching (liquid-solid phase extraction – LSPE) chlorides of rare earth elements by petroleum sulfoxides (PSO). Process of a non-aqueous leaching in our case is considered as direct dissolution of chlorides of metals in the PSO. The received data have shown, that such factors, as a degree of hydration of chlorides of metals, a ratio of phases, temperature and the nature of organic diluent of the PSO render the greatest influence on process of LSPE. Changing the set forth above parameters, it is possible to operate effectively on the process of allocation and separation of metals chlorides. In practice it is the most expedient to apply LSPE for group separation of metals chlorides, for example, for separation of the sum of chlorides of lan thanides from the sum of alkaline and alkali earth elements, and also from chloride of thorium, or with the purpose of group separation of chlorides REE of yttric and ceric subgroups.
On the basis of the data on separation of artificial mixes of chlorides of metals with PSO in con ditions of LSPE in laboratory conditions the circuit of separation of industrial fusion chlorides of metals of Solikamsk magnesian factory have been tested. The laboratory rules is developed and the basic circuit of separation of thorium chloride and the sum of REE from given fusion is offered.
ÕVIII Ìåíäåëååâñêèé ñúåçä ïî îáùåé è ïðèêëàäíîé õèìèè, Ìîñêâà, 2007 SYNERGISTIC EXTRACTION OF LANTHANIDES AND ACTINIDES WITH A MIXTURE OF PICROLONIC ACID AND SULFOXIDES Murinov Yu.I.a, Nikitin Yu.E.a, Kuvatov Y.G.a, Kolyadina O.A.a, Molochnikova N.P.b, Myasoedov B.F.b a Institute of Organic Chemistry Ufa Scientific Center RAS b Vernadsky Institute of Geochemistry and Analytical Chemistry RAS In extraction chemistry of actinides and lanthanides the big attention is given research of properties of extraction systems on the basis of the extractants possessing synergistic effect. Comparing the general laws of metals extraction with sulfoxides and NPOC, it is possible to expect, that sulfoxides should show raising action as neutral donors in synergistic mixtures of extractants. In this connec tion we investigate extraction of lanthanides and actinides with a mixture of sulfoxide – acidic che lating agent. As acidic chelating agent we used picrolonic acid (1-p-nitrophenyl-3-methyl-4-nitro-5 pyrazolon), (PA-5). As have shown results of research, in system PA-5 – sulfoxide with ions of lan thanides and actinides are formed the strong mixed complexes, which stability at comparison with the literary data on an extraction of these elements with mixtures thenoyltrifluorineacetone – TBP or phenylmethylbenzoylpyrazolon – TBP on some orders is higher. It is established, that the extrac tion of lanthanides and actinides with a mixture of PA-5 and sulfoxides submits to the general laws of a synergistic extraction in system of chelating agent neutral donor. With increase of donors ba sicity the extraction grows, and at increase in dielectric permeability and polarity of diluent the ex traction decreases.
Constants of interphase distribution of picrolonates, and also constants of stability and extraction of f-element picrolonates with sulfoxides have been evaluated. Between constants of PADHSO as sociation complexation with the various solvents determined by methods of solubility and GLC, good correlation is observed. Abnormal reduction of acceptor properties of lanthanides picrolonates with increase in a serial number is revealed. Dependence of synergistic effect from acceptor and donor properties of extractable salt and sulfoxides is shown. The given system on the extraction properties considerably surpasses mixture used now « chelating agent + tributylphosphate » and al lows to quantitatively extract trans-plutonium and rare earth elements at acidity of water phase up to 5 mole/l HCI or HNO3.
2518 ÕVIII Ìåíäåëååâñêèé ñúåçä ïî îáùåé è ïðèêëàäíîé õèìèè, Ìîñêâà, DEVELOPMENT OF SCIENTIFIC BASIS OF THE RADIATION SAFETY OF NUCLEAR FUEL EXTRACTIVE REPROCESSING Nazin E.R.a, Zachinjaev G.M.a, Belova E.V.b, Tkhorznitskii G.P.b, Tananaev I.G.b a Scientific and technological centre of nuclear and radiation safety 5/2, st. Malaya Krasnoselskaya, Moscow,119991, Russia b A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences 31, Leninskii prospect, Moscow, 119991, Russia, e-mail: firstname.lastname@example.org At the present time, nuclear power engineering is the most perspective type of energy getting for both the U.S.A. and Russia. Development of large-scale nuclear energy production is oriented to wards closed fuel cycle that implies extraction of U and Pu from spent nuclear fuel (SNF). The most effective way of SNF reprocessing is extraction of the fuel components. Thus, improvement of the current schemes of SNF reprocessing, invention of new ones, and radiation security measures present the most important actual task.
The current and prospective extraction schemes of the SNF reprocessing include intercycle evaporation, nitric acid regeneration, thermal decomposition of uranium and plutonium nitrates, concentration of liquid radioactive wastes, etc. These operations may lead to the exothermic heat explosions that, unfortunately, have already happened several times (Savannah River 1953, 1975;
Oak Ridge 1959;
Tomsk 1993). Their analysis allows to subdivide three possible sources of danger:
(1) interactions of organic component (extractant) with oxidants (nitric acid) with active release of heat due to the irradiation of transuranium elements and fission products;
(2) radiolysis destruction of extractant and aqueous solutions with separation of flammable gases (in particular, hydrogen);
(3) formation of volatile and reactive components during radiolysis of organic and inorganic sub stances in particular, HN3.
In the framework of the expertise of explosives danger of radiochemical technology, we have in vestigated thermal stability of organic mixtures with nitric acid and uranyl nitrate, including both homogeneous and heterogeneous systems. It has been shown that, in the solutions of nitric acid that contain products of transformation and/or radiolysis of extractants and reduction agents, occurrence of exothermic processes is determined by the reactivity of organic components against HNO3. In the experiments, we have determined characteristics of exothermic processes in solutions of some re duction agents in HNO3 that allow to estimate volumetric parameters of gaseous products and their partial pressures. It has been proved that formation of organic extractants in evaporating solutions as a separate phase leads to the explosive oxidation reactions, when reaching critical temperatures of ~130oC in closed vessels. For irradiated systems, the critical temperature decreases to 90oC. The minimal temperatures achieved in these exothermic reactions are from 250 to 400oC, depending upon composition, whereas partial volumes are up to 1.5 L per 1 cm3 of extractant. We have found considerable effect of intensive exothermic reactions in the ‘extractant-HNO3’ systems even at 1 cm thin layer of organic component. This provides the evidence that the evaporation procedure is po tentially explosive already at trace amounts of organic components. The reactions are more inten sive in mixtures with UO2(NO3)2. Though the critical explosion temperatures are higher (170 – 180oC), the temperatures achieved are about 600 – 700oC and remind of the flammation of pyro technical stuff. It can be hypothesized that the irradiation would reduce the critical temperatures.
ÕVIII Ìåíäåëååâñêèé ñúåçä ïî îáùåé è ïðèêëàäíîé õèìèè, Ìîñêâà, 2007 ACTINIDE (III, IV) AND LANTHANIDE PHOSPHATES CHEMISTRY AND CRYSTAL CHEMISTRY. REVIEW AND PROSPECTS Orlova A.I.
Nizhegorodskyi State University, Nizhnyi Novgorod, Gagarin av., 23 Russia Investigation results in the field of synthesis, structure formation and properties of actinide (III, IV) and lanthanide anhydrous orthophosphates are summarized in the report. Interest for this theme is retained from the discovery of minerals as thorium, uranium, rare elements raw sources and is ex tended up today because of development of technology of reprocessing of irradiated nuclear fuel and conversion of “excess” weapons plutonium to mixed oxide fuel for new generation nuclear re actors. Phosphate methods are have appeal for specialists because of development of the concept of phosphate mineral like matrix as safe form of concentrating of dangerous high level wastes contain ing actinides and isolation them from biosphere. Such of current importance technological and eco logical problems may be solvent successfully on the base of fundamental knowledge in the field of chemistry and crystal chemistry of simple and complex chemical systems containing actinides to gether with various elements of nuclear fuel cycle.
Comparison of calculated (possible) formula compositions of orthophosphates of actinide and lanthanide elements, also their chemical analogues-compounds containing tetrahedral oxoanions (vanadates, arsenates and others) with known today ones was carried out. It was established that list of investigated phosphates is very small and includes a little portion from theoretical formula com positions. Also there was found that the main structure modifications were presented by some struc ture forms and among then mineral like structure forms are the most. These are monazite, zircon, glazerite, kosnarite, whitlockite, eulytite, langbeinite and some others. Lanthanide compounds are more representative. Such investigations are wider. They relate not only to radiochemical problems.
Coordinative neighborhood in MetOn-polyhedron varies from 10 up to 6. Each realized structure possesses wide isomorphism of cations and anions (iso- and heterovalent). At some cases polymor phous transitions take place, including transitions with full reconstruction of coordinative poly hedra.
New predicted compounds were synthesized by mean of improved methods: the stages of press ing including high temperature ones, sol-gel process including strong organic complex formation, precipitation, recrystallization into molten salts and others. The known and new data on thermal, thermal mechanical, radiation and chemical stability of actinide and lanthanide phosphates are dis cussed.
The regularity of influence of compositions, synthesis conditions on structure modification and crystallographic characteristics of f-element phosphates and regularity of their changes in the rows of analogues were determined.
On the base of crystal chemical forecast new phosphates of actinides (thorium, uranium, neptu nium, plutonium, americium, curium), lanthanides and solid solutions possessing the structure of NaZr2(PO4)3-type, monazite, langbeinite and whitlockite were designed and prepared recently. The characteristics of their stability on extreme conditions were determined. Behavior under influence over destroying factors of nature and technology types (heating, thermal “shocks ‘, radiation and chemical effects) were studied. These data are presented here.
2520 ÕVIII Ìåíäåëååâñêèé ñúåçä ïî îáùåé è ïðèêëàäíîé õèìèè, Ìîñêâà, IMPROVEMENT OF TECHNOLOGY FOR NITRIC-ACID EXTRACTION AFFINAGE OF URANIUM Ostrovsky Yu.V.a, Zabortsev G.M.b, Aleksandrov A.B.c, Saifutdinov S.Yu.c, Khlytin A.L.c a Russia, FGUP Novosibirsk State Design Research Institute «VNIPIET», b Russia, Novosibirsk, «EIDOS», c Russia, Novosibirsk, «NCCP, Inc.»
E-mail: email@example.com The process of extraction affinage of uranium at nuclear facilities results in generation of uranium containing liquid waste – extraction raffinates – with concentration of nitric acid from 60 g/l up to 240 g/l. Before discharge into the tailing pit, the solutions are neutralized by calcium hydroxide (ammonium) that ensures formation of poorly soluble compounds of non-ferrous, heavy and radio active metals.
So far, no acceptable methods for denitration of liquid waste have been developed. For instance, removal of nitric acid from the liquid waste has not become widely used because of noticeable cor rosion of structural materials due to the presence of the fluorine ion.
To reduce consumption of nitric acid and discharge of nitrite ions together with liquid waste, we have developed the low-waste technology for nitric-acid extraction affinage of uranium, which pre supposes use of urea nitrite as a recyclable salting-out agent. The said urea nitrate is obtained in the process of heat-free carbamide denitration of extraction raffinates.
The distinctive feature of a suggested technology is that dissolution of uranium concentrate is carried out with a minimal excess of nitric acid using currently available process equipment at tem peratures that are 10-150C above routine working temperatures. Urea nitrate obtained in the process of carbamide denitration of extraction raffinates, is added prior to extraction to the solution of uranyl nitrate to ensure concentration of free nitric acid at 1,5-2,0 mol/l.1 Extraction of uranium in the presence of urea nitrite proceeds without any complications.
Filtrate obtained after removal of the urea nitrate sediment from extraction raffinate, undergoes galvanochemical treatment in the vertical vibration reactors in a field of “iron – carbon” galvanic couple with separation of uranium-containing iron hydroxides and subsequent selective carbona ceous leaching of uranium which is then returned to the initial stage of the process;
this makes it possible to avoid irretrievable losses. Liquid tailings purified by galvanochemical method are not ranked as liquid radwaste and do not need special storage conditions.
To test the suggested technology, large-scale laboratory experiment has been performed at NCCP, Inc. It resulted in the production of ceramic uranium dioxide through precipitation of am monium polyuranate (ADU-process). The experiment has shown that the use of urea nitrate as a recyclable salting-out agent in the process of extraction affinage of uranium makes the total con sumption of the nitric acid 1.5-2.0 times less, considerably reduces saline nitrite-ion discharge into the tailing pit, saves alkaline reagent used for neutrolization with complete maintaining of all the quality properties of the final product.
References 1. Yu.V. Ostrovsky, G.M. Zabortsev, A.B. Aleksandrov, A.I. Drobyaz, S.Yu. Saifutdinov, A.L. Khlytin. Patent of the Russian Federation ¹ 2295168 dated 13.10.2005.
ÕVIII Ìåíäåëååâñêèé ñúåçä ïî îáùåé è ïðèêëàäíîé õèìèè, Ìîñêâà, 2007 PREPARATION OF THE HIGHER OXIDATION STATES OF COBALT AND THEIR IDENTIFICATION BY EMISSION MSSBAUER SPECTROSCOPY Perfil'ev Yu.D.
Chemical Department,Lomonosov Moscow State University, Moscow, Russia In most Mssbauer experiments the substance under investigation is the absorber which contains the resonant isotope (57Fe as an example) in its ground state. But the source substance may also be object of study for the parent radioactive isotope (57Co in the case of 57Fe) as it produces the daugh ter resonant isotope in the excited state (57mFe) which can provide information about the initial chemical state of the parent atom. This direction of emission Mssbauer spectroscopy was used with the intention of studying higher oxidation states of cobalt1.
Reliable evidence of obtaining exists only for tetravalent cobalt compounds. This was a reason for which the method matrix stabilization2 was used for the preparation of the compounds in which CoV and CoVI ions may be included. It consists in the following: an ion in unstable degree of oxida tion is isomorphically introduced into stable compound of an isovalent element (the pentavalent compounds of manganese or vanadium for example).
For comparative study the several matrices were simultaneuosly doped by iron 57Fe and carrier free 57Co. The transmission and emission spectra of the samples taking into account changes of source and absorber functions are similar. It leads to conclusion that the oxidation states of iron and cobalt are similar and they undoubtedly correspond to the forms of iron and cobalt from IV to VI as it is following from the values of the isomer shifts.
This work was supported by the Russian Foundation for Basic Research (project 05-03-33079).
References 1. L.A. Kulikov, Yu.D. Perfiliev, N.S. Kopelev, J.Phys.Chem.Solids, 1995, 56, 1089.
2. Yu.D. Perfiliev, Ros. him. zhournal, 1998, 17, 47.
2522 ÕVIII Ìåíäåëååâñêèé ñúåçä ïî îáùåé è ïðèêëàäíîé õèìèè, Ìîñêâà, COMPARATIVE STUDY OF COMPLEXING ABILITY OF 99MTC AND 188RE WITH POTASSIUM SALT OF HYDROXYETHILIDENEDIPHOSPHONIC ACID Petriev V.M.
4, Korolev St., Obninsk 249036, Kaluga region, Russia, State Institution – Medical Radiological Research Center RAMS (SU-MRRC RAMS) The given literatures testify that radiopharmaceuticals on a basis biphosphonate labeled 99mTc and Re are perspective for diagnostics and treatment of oncological diseases.
Chemical properties of technetium and rhenium are similar, but not identical. In particular, at re duction Tc(VII) up to Tc (IV) and Re(VII) up to Re (IV) oxidation-reduction potential of rhenium (510 mlV) is lower, than at technetium (738 mlV). It testifies that Re (VII) complexes in the maxi mum valence state thermodynamic are more stable steadier than analogues of Tc(VII). More stable state of perrhenat-ion make difficult its reduction up to 4-and a 5-valent state in comparison with pertechnetat-ion. The technetium and rhenium forms complex compounds with organic ligands in 4-and a 5-valent state.
The purpose of the present work is in carrying out of comparative investigations of regularity formation of complex compounds of 99mTc and 188Re with potassium salt hydroxyethylidenediphos phonic acid (KHEDP).
For reduction of 99ìTc and 188Re used Sn2+. Comparative investigations of regularity of 99mTc and 188Re bunding with KHEDP have shown, that reaction rate and efficiency of binding radionu clides with ligand substantially depends on conditions of carrying out of reaction. Regularity of formation of complex compounds of 99mTc and 188Re with KHEDP essentially differ at low concen tration of Sn2+ (in an interval of 0,008-0,84 microM/ml). For effective 99mTc binding with KHEDP (95% are higher) minimal Sn2+ concentration are 0,08 microM/ml. In an interval of Sn2+ concentra tion 0,08-0,84 microM/ml reaction rate of formation complex 99mTc-KHEDP is high and efficiency of binding technetium with ligand have no considerable differences. While formation complex compounds of 188Re-KHEDP in this interval of Sn2+ concentration occurs essentially to smaller rate and is significant with smaller efficiency.
As a result of studying of pharmacokinetic characteristics of 99mTc-KHEDP and 188Re-KHEDP in organism of rats it is shown, that these two complex compounds having identical structure, sub stantially differ on chemical properties. Character of their behaviour testifies to it in organism.
Re-KHEDP in higher concentration, than 99mTc-KHEDP, uptake in soft tissues, and rate of its removing from soft tissues is higher. In a bone tissue, on the contrary, values of accumulation of 99m Tc-KHEDP are higher, than 188Re-KHEDP, and it from a bone tissues much more slowly, than Re-KHEDP is eliminated.
ÕVIII Ìåíäåëååâñêèé ñúåçä ïî îáùåé è ïðèêëàäíîé õèìèè, Ìîñêâà, 2007 STUDY OF INFLUENCE OF CALCINATION TEMPERATURE ON U3O8 SAMPLES SOLUBILITY AND SORPTION BEHAVIOUR TOWARDS Np(V) Petrov V.G.a, Kalmykov St.N.a, Batuk O.N.a, Zakharova E.V.b a Chemistry Department of Lomonosov Moscow State University, Moscow 119992, Russia, b Frumkin Institute of Physical Chemistry and Electrochemistry of RAS, Moscow, Russia, Enriched uranium fuel production results in accumulation of huge amount of depleted uranium (DU), which is stored on a daylight surface in the form of uranium hexafluoride (UF6). One of the possible ways of DU utilization is to use its oxygen compounds as a component of barrier system in nuclear waste repositories. Earlier the possibility of DU utilization in the form of uranium dioxide was proposed and investigated. These studies showed that uranium dioxide samples synthesized at different temperature conditions demonstrate different solubility rates and sorption behavior toward neptunium (V).
Industrial production of UO2 is conducted through U3O8 production step. Therefore the study of U3O8 behavior in the environmental conditions is essential from the point of view of its application as a component of the barrier material.
The goal of our study was the investigation of calcination temperature influence on solubility of U3O8 samples and their sorption behaviour towards 237Np(V), which has long half-life and high mi gration ability under environmental conditions.
Studied U3O8 samples were synthesized by calcination of industry produced UO2 in air at 600oC, 700oC and 800oC. Specific free surface area of samples was determined by BET analysis. Average particle size was determined by dynamic light scattering. Surface morphology of samples was stud ied by scanning electron microscopy. Stoichiometry of the samples was determined by polarogra phy. Composition of samples was analyzed by XRD.
Solubility and sorption experiments were conducted under oxidizing conditions in simulated groundwater and in MilliQ water in batch conditions. Ratio of solid phase to solution in all experi ments was kept at 2.5 g/l.
Kinetics of solubility of the sample produced at high temperature was slower as compared to sample annealed at low temperature. All studied samples have the same composition, free surface area, porosity and average particle size. Within 100 days the solubility riches the same value for all samples. Neptunium sorption is higher for more soluble sample in simulated groundwater and in MilliQ. Maximal value of sorption was calculated from isotherms of Np(V) sorption.
Work was financially supported by ISTC (project 2694).
2524 ÕVIII Ìåíäåëååâñêèé ñúåçä ïî îáùåé è ïðèêëàäíîé õèìèè, Ìîñêâà, APPLICATION OF SPECTROELECTROCHEMISTRY FOR STUDING SPECIATION OF URANIUM AND NEPTUNIUM IN CHLORIDE MELTS Polovov I.B.a, Sharrad C.A.b, May I.b, Volkovich V.A.a, Vasin B.D.a a Department of Rare Metals and Nanomaterials, Ural State Technical University – UPI, Russia b Centre for Radiochemistry Research, The University of Manchester, Manchester, UK Molten salts have potential applications in innovative pyrochemical actinide processing and separa tions techniques. The development of safe and reliable technologies requires sound understanding of the key electrochemical processes occurring in molten salts. Direct information concerning coor dination properties of actinides can be obtained using electronic spectroscopy. Combination of elec trochemistry and spectroscopy in one spectro-electrochemical cell provides valuable information concerning speciation in studied systems.
In the present work we conducted in situ spectroscopic studies of anodic dissolution of uranium, electrochemical oxidation of U(III) and electrochemical reduction of U(IV), U(VI) and Np(IV) ions. All experiments were performed in LiCl-KCl eutectic melt at 450°C. All electrochemical measurements were performed vs. chlorine or silver/silver chloride reference electrodes. Uranium was introduced into the melt by anodic dissolution of the metal or by dissolving anhydrous uranium tetrachloride. Np(IV) containing samples were prepared by chlorinating hydrated Np(IV) oxide by HCl in the melt.
Anodic dissolution of metallic uranium results in the formation of UCl63- ions. Uranium(III) spe cies are also formed during prolonged contact of LiCl-KCl-UCl4 melt with U metal and cathodic reduction of such electrolyte. Several experiments involving spectro-electrochemistry of ura nium(VI) species were also successfully performed. These involved cathodic reduction of uranyl containing melts. The reduction of UO22+ is a complex process – together with the formation of uranium(V) ions, UO2+, some precipitation of solid UO2 was observed.
The spectral picture of neptunium electroreduction is presented in Fig. 1. Initial spectrum of Np(IV) corresponds to the chloride complex of neptunium(IV), NpCl62-. The spectral profile of the final obtained spectrum is typical of Np(III) complex, NpCl63-. There are five isobestic points at 625, 785, 822, 842 and 870 nm (Fig. 1) indicating that the only one reaction of reduction of NpCl62 into NpCl63- was taking place and the total concentration of neptunium in the melt remained un changed. After prolonged electroreduction the intensity of the final spectrum in the entire wave length range began to decrease due to the reduction of Np(III) to neptunium metal.
0. NpIV 0. NpIII NpIV Absorbance NpIV III Np NpIII 0. NpIV III Np 0. 0. 400 500 600 700 800 900 Wavelength, nm Fig. 1. Spectra recorded during electrochemical reduction of Np(IV) to Np(III) in LiCl-KCl eutec tic melt at 450°C. Initial concentration of neptunium (IV) – ca. 0.015 mol/l. Total time of reduction – 1280 sec, current – 5 mA.
IBP thanks INTAS (Grant No. 03-55-1453) for financial support.
ÕVIII Ìåíäåëååâñêèé ñúåçä ïî îáùåé è ïðèêëàäíîé õèìèè, Ìîñêâà, 2007 PROGNOSIS OF RADIONUCLIDES BEHAVIOR IN NATURAL WATER BASED UPON DETERMINATION PHYSICOCHEMICAL STATE OF THEIR STABLE CHEMICAL ANALOGS Polyakov E.V.a, Khlebnikiov N.A.a, Surikov V.T.a, Trapesnikov A.V.b, Udachin V.N.c a Institute of solid state chemistry, UD RAS, 620014, Ekaterinburg, Pervomajskaya, b Institute of plant and animal ecology, UD RAS, 624250, Sverdlovsk reg., Zarechny, a/b18, Biophysical Station c Institute of mineralogy UD RAS, 456301, Chelyabinsk reg., Miass Chemical elements behavior in heterogeneous media is governed by physicochemical rules of their phase partitioning and depends predominantly on the chemical state of these elements in the con tacting phases. This problem is being discussed in the presentation in connection with general topic of radionuclides sorption behavior prediction in river waters. Variation in the physicochemical state of radionuclides such as Cs, Sr, U and their natural analogs in the river Techya (Chelyabinsk reg.) is analyzed in the presentation in connection with seasonal variation of chemical composition of wa ter. Determination of the physicochemical state of natural isotopic mixture of Sr, U, REE and Th was fulfilled at the summer-autumn period of the year 2006, using fresh samples of river water. Ex perimental data on ultra-filtration of the water through membrane composites covered with TiN, raster electron microscopy of these membranes, multi-element ion-exchange partitioning of minor elements between the river water and strong cation-exchanger were obtained and analyzed. Using the experimental data together with results of thermodynamic simulation of the minor elements ion exchange behavior, an immediate correlation was estimated between seasonal variation of river wa ter chemical composition, the concentration of soluble CO2 in it and fractional composition of all known chemical species of Sr(II), U(VI), PÇÝ(III) and Th(IV). It is shown that chemical state of Sr(II) and U(VI) is strongly depends on the level of carbonate species in the river water. High level of the carbonate in the water leads to the formation colloid suspension of CaCO3 which is able to co-precipitate up to 10-15% Sr(II) and up to 20% U(VI). CaCO3 phase is supposed localized at the surface of mineral and biological suspensions and have the size 3 mkm. The rest of Sr(II) exists in the river water in the form of aqua-cations. Uranium (VI) is presented in the water as a set of hy droxo- and carbonate complexes which don’t interact with cation-exchanger (non- “sorbable” spe cies), and in the form Ca2UO2(CO3)3 which may be involved in the ion-exchange interaction (“sorbable” species). Th(IV) and REE are found exist in the water as a hydroxo-complexes (80%) and in the form of suspension (20%). The CO2 concentration in the river water descends to the level which is characteristic for autumn period, the suspended CaCO3 vanishes and fraction of Ca2UO2(CO3)3 in the water changes. Specific activity of Sr-90 correlates with this conclusions.
This work is supporting by an integrated project RD RAS – SD RAS – NAS of Ukraine, and also by grant of Scien tific school HØ-8380.2006.3.
Fig. Isotherm of U(VI) sorption by ÊÓ2(Na) in river water (big points) and results of semi quantitative modeling of the process (little points).
2526 ÕVIII Ìåíäåëååâñêèé ñúåçä ïî îáùåé è ïðèêëàäíîé õèìèè, Ìîñêâà, SOLUBILITY OF MONAZITE IN NATURAL HUMIC ACID CONTAINING SOLU-TIONS AND SORPTION BEHAVIOR OF THE SOLUTE Polyakov E.V.a, Khlebnikov N.A.a, Surikov V.T.a, Zhernakova Z.M.a, Volkov E.V.b a Institute Of Solid State Chemistry, UB RAS, 620014, Ekaterinburg, Pervomajskaya, b Chemical Department Of The Ural State University named after A.M. Gorky, 620083, Ekaterinburg, K-83, Lenin pr., Characteristic features of the monazite are high structural, chemical and radiation resis-tance. These properties of the monazite and of its synthetic analogs (for example, double Ti or Zr phosphates) attract attention of investigators as a characteristics of perspective materials for sorption barriers and for high level radioactive wastes immobilization. Chemical stability of these phases is usually being characterized by their solubility in dilute aqueous solutions and/or distilled water. Chemical behavior of monazite toward natural water with high level of organic matter, including humic and fulvous acids is unknown up to now. This unaccounted factor should nevertheless be of great im portance for prediction of accident consequences resulted from direct contact of monazite and monazite-like artificial materials with soil and ground waters and atmospheric precipitates during long-term storage of such a materials.
In the presentation are shown comparative results of the investigation of monazite (parti-cle size 0,2–0,4 mm) chemical solubility in samples of natural river water (with NaCl as an additive) and in the samples of natural water with high concentration of humic acids (97 mass.% of HA) as a func tion of pH. Overall concentration of spirit-soluble fraction of the HA in the water samples under investigation is 850–900 mg/L.
Investigation of ion-exchange behavior of the monazite dissolution products in HA solu-tion is carried out using ICP-MS, ultra-filtration and thermodynamic simulation pro-cedures. In the filtra tion experiments both ordinary nuclear membranes and composite ones (membranes covered with TiN films) are used.
It is shown that solubility of monazite in natural river water in conventional temperature condi tions rise up an order of magnitude in the presence of HA and varies with pH of liquid phase (see Figure). Sorption of the dissolved elements by a cation-exchanger is shown de-pend both on the formation of humic complexes by these elements and on chemical behavior of free HA. Acid ex traction from solid phase and ion-exchange behavior of principal constitu-ents of the monazite such as La, Ce, Pr, Th, U, Pb, Bi, Tl, Si, Fe, Al, Sr show that namely sorption of there HA complexes may be a process, responsible for blocking migration of these elements in soil. Recommendations for the monazite constituents migration prevention into soil and aquifer are formulated.
Figure. Example of solubility of monazite with regard to Ti in natural river water with (1) and without HA (2).
This work is carrying out in the framework of grant HØ-8380.2006.3.
ÕVIII Ìåíäåëååâñêèé ñúåçä ïî îáùåé è ïðèêëàäíîé õèìèè, Ìîñêâà, 2007 CHEMICAL STABLE ALLOYS OF ACTINIDES WITH NICKEL, THEAR SINTESIS AND PROPERTIS Popov I.B., Ivanov V.V., Kuznetsov D.G.
Institute of Physical Chemistry and Electrochemistry of the Russian Academy of Sciences.
Moscow, Leninskiy pr., 31.
Various materials have been proposed for immobilization of high-level radioactive radionuclides, i.e., their inclusion into the composition of matrices used during long-term storage of nuclear wastes. These are mainly ceramics, minerals or glassy compositions. However, thus far practically no body considered the application of alloys or intermetallides compounds of radionuclides for these pur poses though;
such systems have a number of advantages over nonmetal materials, particularly, in the case of actinides. This might be accounted for by the specific difficulties of producing actinide metals and alloys by routine metallurgical methods. Therefore, the utilization of metal matrices for a long-term storage of actinides largely depends on the development of a simple method of their synthesis.
The main advantages of metal matrices (alloys, intermetallides) are their high conductivity and as a consequence, the absence of the charging phenomena, namely, electroerrosion leading to destruction of dielectrics. These materials have high density (12 -16 g/cm3}, may contain as high as 85% mass.
of an actinide and have thermal conductivity typical of metals.
We propose the method of electrolysis of melts and chlorides in eutectic mixtures of alkali metals to produce foils of intermetallides of plutonium and americium compounds with nickel. Electrodepositing was carried out at the temperature of the electrolyte of 400- 500°C;
the electrode voltage was 2.9 -3.3 V at a current density of 10-100 mA/cm2.
In this variant, the process of producing intermetallics compounds does not imply the use of aqueous solutions and thus does not give additional liquid nuclear wastes.
At the initial stage of the electrolysis process, phase of AnNi2 is formed on either sides of the cathode.
Further gradual spread of this phase deep into the cathode-substrate leads to the formation of a con tinuous foil of this compound, and then a new intermetallic phase is formed inside this foil. This AnNi phase enriched with the deposited element keeps spreading toward the substrate surface. However, this does not lead to the formation of a continuous AnNi foil, because the spreading of this zone is accompanied by the formation inside the AnNi phase of the intermetallide An3Ni, which is still richer in the actiniae. These two zones (phases) keep spreading toward the cathode-substrate surface to form almost a continuous An3Ni foil.
The investigations performed show that the electrolytic method may provide the formation of inter metallides compounds of rare ease elements, americium and plutonium of various compositions and composites with a high chemically, thermal and radiation stable.
Elaborated the leaching rate, thermal stable and other physicochemical properties of the ameri cium-241 and plutonium-239-238 intermetallides containing up to 80% mass. of radionuclide.
2528 ÕVIII Ìåíäåëååâñêèé ñúåçä ïî îáùåé è ïðèêëàäíîé õèìèè, Ìîñêâà, PHYSICOCHEMICAL ASPECTS OF REMEDIATION PROCESSES IN RADIONUCLIDE CONTAMINATED GROUNDS AND WATERS Pshinko G.N.a, Spasonova L.N.a, Kornilovych B.Yu.b a A.V. Dumansky Institute of Colloid and Water Chemistry of NAS of Ukraine, Ukraine, 03680, Kyiv-142, Vernadsky av., b National Technical University of Ukraine “KPI”, Ukraine, 03056, Kyiv, Peremogy pr., 37, E-mail: firstname.lastname@example.org Contamination of the environment with the radionuclides is a negative consequence of the nuclear power engineering, and this essentially impacts the ecological conditions. The primary hazard of the radioactive precipitation is in close association with the active inclusion of the long-term toxic ra dionuclides of the man-caused and natural origins in the geochemical and biological cycles. These radionuclides are characterized with different mobility in the aqueous media and soils. Herein, there become apparent not only properties of the radionuclides but also the physicochemical features of the aqueous media and soils, in particular, both nature and concentration of the organic matter. This is of essential importance predominantly for the radionuclides forming the strong enough com plexes, mineralogical and granulometric composition of soils and suspended matter, pH, etc.
In the message given, an effect of the structure of the aluminosilicates, chemical nature of the ra dionuclides, the complexation reactions with the humic matter, EDTA, NTA, HAc, Na2CO3 on the Cs, 90Sr and U(VI) sorption-desorption processes in the natural silicate systems has been studied.
An effectiveness in purification of different aqueous media from the U(VI), 137Cs and 90Sr radionu clides by the sorption method using the natural aluminosilicates and the clay-containing slimes and soils as well as using different chemical reagents has been compared. An interaction of the cesium and strontium ions with the organic components of the surface waters and soils with the humic mat ter is shown is nonspecific one as opposed to the uranium. A stability of the complexes with the or ganic components of soils (both the fulvic and humic acids) is rather considerable. Based on the data reached with employment of the minerals differing in their structure and sorption capacity, the sorption mechanism has been characterized: an availability of the so-called ditrigonal holes formed with bases of the silicate-oxygenous tetrahedrons comparable with a radius of the cesium hydrated ions is an important factor causing an increase in selectivity of the laminated silicates to the cesium ions. This determines an opportunity of the intense interaction of the cesium ions with those of oxy gen composing the SiO4 tetrahedron up to their partial dehydration and immersion into the ditrigo nal holes, whereas such a mechanism is impossible for the hydrated strontium ions having a higher radius. As to U(VI), side by side with its ion-exchange capacity, the forms of its existence (deter mined based on the stability constants of the complexes of uranium in the solution in the presence of the complexing agents and in their absence), concentrations of humic and fulvic acids as well as other reactants in water and soil media, pH of medium have an essential importance. An availability of the complexing agents in the aqueous media (fulvic acids, EDTA, NTA, etc.) causes an essential reduction in absorption of the (VI) uranium with the clay minerals resulting, at their considerable concentrations, in an actually complete suppression of the sorption process. Based on the desorption data, it has been demonstrated an expediency to use the EDTA as a desorbing agent to purify the uranium-containing soils: both in the purification effectiveness and going from the ecological view point. At the same time, our desorption investigations from the 137Cs microquantities of the clay containing soils and sludges demonstrated their faster fixation on the highly-selective centers – as opposed to the 90Sr. Further, the purification effectiveness is determined first of all by the structure of a mineral. The mixed reactants of the acid and ammonium salts are the most effective ones.
ÕVIII Ìåíäåëååâñêèé ñúåçä ïî îáùåé è ïðèêëàäíîé õèìèè, Ìîñêâà, 2007 PRODUCTION OF METAL RUTHENIUM FROM IRRADIATED TECHNETIUM Rotmanov K.V.a, Lebedeva L.S.a, Radchenko V.M.a, Tarasov V.A.a, Romanov E.G.a, Toporov Yu.G.a, Peretroukhin V.F.b, Kozar A.A.b a Federal State Unitary Enterprise State Scientific Centre- Research Institute of Atomic Reactors, Dimitrov grad 10, Ulyanovsk region, 433510 RUSSIA, email@example.com b Institute for Physical Chemistry and Electrochemistry RAS, 31 Leninsky prosp., Moscow, 119991 Russia A number of experimental irradiations have been carried out during last two years within the on going research program. A set of technetium targets in the form of metal discs of 6 mm in diameter and 0.3 mm thick was irradiated in the neutron trap of the SM high flux reactor at RIAR. The tar gets were unloaded from the reactor in three batches after each of them had achieved a desirable burn-up value. The irradiated samples were found to be technetium alloys containing 19, 45, and 70% of ruthenium.
Results of chemical reprocessing of the irradiated targets and those of obtaining artificial ruthe nium metal are presented in the report. The targets were dissolved in the potassium hydroxide solu tions containing potassium periodate KIO4 followed by precipitation of ruthenium (IV) hydroxide by adding ethanol. To purify it from technetium impurity, ruthenium was distilled as RuO4 into the ethanol solution, where it was reduced and precipitated as ruthenium (IV) hydroxide.
To obtain metal ruthenium, Ru(IV) hydroxide precipitate was converted to dioxide RuO2 and re duced to the metal state in hydrogen atmosphere at 400 °C.
The isotopic composition of the prepared artificial metal ruthenium, depending on technetium burn-up was found to be as follows: 100Ru 98.93%,101Ru 0.54% for technetium burn-up of 19%, Ru 97.94%, 101Ru 1.35% for technetium burn-up of 45% and 100Ru 97.42%, 101Ru 1.79% for technetium burn-up of 70%.
Content of heavy ruthenium isotope, such as 102Ru and 104Ru, did not exceed 0.8%. So, ruthe nium metal prepared seems to be practically a mono-isotope. So it differs from natural ruthenium which has seven stable isotopes.
2530 ÕVIII Ìåíäåëååâñêèé ñúåçä ïî îáùåé è ïðèêëàäíîé õèìèè, Ìîñêâà, STUDY OF AMERICIUM-CUPRUM, CURIUM-FERRUM AND CURIUM-RUTHENIUM ALLOYS Ryabinin M.A., Radchenko V.M., Tomilin S.V., Pichuzhkina E.M., Chernakova T.A., Nagaytsev V.G., Yakovenko A.G.
Federal State Unitary Enterprise State Scientific Center-Research Institute of Atomic Reactors Dimitrovgrad 10, Ulyanovsk region, 433510 Russia, firstname.lastname@example.org Results of X-ray study of the crystal structure of the Am-Cu, Cm-Fe and Cm-Ru samples obtained by condensation of metal actinides vapors on the backplates of the corresponding metals are pre sented.
Intermetallic compound Cu5Au (Cu7Am) with a hexagonal lattice of the Cu5Ca (Cu7Tb)-type and the crystal lattice parameters a = 4,958(1), c = 4,175(2) was found in the Am-Cu system.
Intermetallic compounds Cm2Fe17 with a hexagonal lattice (a=8,406±0,003, c=8,122±0, ) and CmFe2 with a cubic lattice (a=7,213±0,002 ) were found in the Cm-Fe system.
Mutual solubility of the components was not found at room temperature.
Intermetallic compounds Ru2Cm with a hexagonal lattice and Ru3Cm with a cubic lattice were found in the Cm-Ru system. The parameters of their crystal lattices were calculated:
a = 5,279(1), c = 8,812(3) – for Ru2Cm;
a = 4,151(2) – for Ru3Cm.
Data on X-ray amorphization of the found intermetallic compound lattices under the influence of Am and 244Cm alpha decay were obtained.
ÕVIII Ìåíäåëååâñêèé ñúåçä ïî îáùåé è ïðèêëàäíîé õèìèè, Ìîñêâà, 2007 BEHAVIOUR OF Np(V), U(VI) AND Cs IN GEOCHEMICAL BARRIERS ON THE BASIS OF BENTONITE AND NATURAL CLAY MINERALS Sabodina M.N.ab, Kalmykov St.N.b, Artem'eva K.A.b, Zakharova E.V.a a Chemistry dept., Radiochemistry div., Lomonosov Moscow State University, Moscow, Russia b Frumkin Institute of Physical Chemistry of Russian Academy of Science, Moscow, Russia Low-level nuclear wastes containing transuranium elements (TRU nuclides) such as neptunium are generated in spent nuclear fuel treatment procedure. The safe disposal of radioactive waste in geo logical formations is based on what is known as multi-barrier concept. Bentonite is a natural clay mineral that has high sorption capacity towards cations and is proposed in several countries as a main component of isolation barriers at the nuclear waste repository sites. However, the possible use of sandy soils with high clay content is considered for this purpose as well.
The presence of colloid particles is essential for radionuclide transport and should be considered in design of such barriers. For bentonite pore waters that have reducing Eh values actinides could be present in the form of intrinsic hydroxocolloids or sorbed onto natural aquatic colloids forming so called pseudocolloids. Presence of surface coatings on colloidal particles may change their coagula tion properties (e.g. Fe(III) oxide coating or humic coating). The aim of this work was to study acti nide speciation in bentonite pore waters and sorption of 237Np(V), 137Cs, 238U(VI) by clayey soils including possible role of surface coatings on it.
For experiments with natural clayey sols, samples were fractionated granulometrically (0. 0.25mm;
50m 10m and 10m). For each fraction specific surface area and po rosity, were determined. For natural clayey soils the highest specific surface area correlated with Fe(III) content and was highest for the largest fraction (0.5 0.25 mm) and the finest fraction (10m). All samples were characterized by SEM and TEM. It was established by SEM, that Fe is present both in the form of separate hematite particles, and in the form of surface coatings. Chemi cal forms of iron in the sample were defined by a method of Electron Energy Loss Spectroscopy near-edge fine structure on L 2,3 edges of Fe.
The sorption of radionuclides was studied by initial clayey soil samples and by samples after ex traction of Fe amorphous compounds (by Tamm methods described by Vorob'eva, 1998). The high est sorption of actinides (Np and U) correlated with Fe(III) content. The extraction of Fe(III) from the samples result in significant decrease of actinide sorption. Indicating, that sorption of actinides is defined by presence of surface coatings of Fe(III) compounds. Presence of Fe(III) surface coat ings did not effect on Cs sorption.
On the basis of the received data recommendations on concerning the application of various clays, used for design of barriers in various repository of radioactive waste are given.
2532 ÕVIII Ìåíäåëååâñêèé ñúåçä ïî îáùåé è ïðèêëàäíîé õèìèè, Ìîñêâà, EXTRACTION PROPERTIES OF AMINOACID DERIVATIVED BASED LIGANDS REGARDING TO URANIUM (VI) AND EUROPIUM (III) IN TWO PHASE AQUEOUS SYSTEMS Safiulina A.M.a, Borisova N.E.b, Knizhnikov V.A.c, Misheliya A.L.d, Reshetova M.D.b, Tananaev I.G.d a Institute of Geochemistry and Analytical Chemistry of Russian Academy of Science, Moscow, Russia b Lomonosov Moscow State University, Chemical Department, Moscow, Russia c Institute of Physicoorganical chemistry of NAS Byelorussia, Minsk, Byelorussia d Institute of Physical Chemistry and Electrochemistry of Russian Academy of Science, Moscow, Russia Extraction of transuranium elements from complexing medium in high pH range (8 – 11) is an ac tual challenge of modern radiochemistry and radioecology. One of possible directions of its solution consists in the use of biphase water systems with water-soluble polymers in combination with effec tive complexing ligands. We have been carried out systematic research of extractive and complex ing properties of the large series of the new ligands based on aromatic and heteroaromatic dicar bonyl compounds and derivatives of amino acids (1).
H H N A N R R OH OH OH C C O O OH R =O NH = A NH2 N NH NH NH S N CH H c b OH a 1a 1b (1).
Research of uranium(VI) and europium(III) extraction from sulphate and carbonate medium al lowed to establish the rules of change of metal ions distribution factor depending on structure of complexing ligand. On the basis of the researches carried out is possible to conclude that extraction of highvalency actinides occurs selectively at use of the ligands, containing a phenolic fragment, while low-valency lanthanides selectively extract at presence of pyrrol derivatives. At that leading in extracting agent molecule aminoacid residue of methionine raises extraction ability. Change of the nature of the central fragment allows to vary the selectivity of extracting agents concerning ions of metals, and change of the nature aminoacid residue allows to raise the extraction degree.
ÕVIII Ìåíäåëååâñêèé ñúåçä ïî îáùåé è ïðèêëàäíîé õèìèè, Ìîñêâà, 2007 N-ORGANOPHOSPHORYLUREAS – THE NEW TYPE OF EXTRACTION AGENTS FOR CONCENTRATING AND SEPARATION OF 4f- AND 5f-ELEMENTS Safiulina A.M.a, Goryunov E.I.b, Baulina T.V.b, Goryunova I.B.b, Letushov A.A.c, Tananaev I.G.c, Nifant’ev E.E.b a Institute of Geochemistry and Analytical Chemistry of Russian Academy of Science, Moscow, Russia b Institute of Organoelement Compounds of Russian Academy of Science, Moscow, Russia c Institute of Physical Chemistry and Electrochemistry of Russian Academy of Science, Moscow, Russia With the purpose of search of new types effective, selective and cheap bidentate neutral organo phosphorus chelating agents for actinides and lanthanides extraction from acidic liquid radioactive waste solutions (LRW) simple, effective and practically feasible “one-pot” methods of synthesis of N-organophosphorylureas are developed and extraction ability of these compounds relative to 4f and 5f-elements was investigated.
The investigations have been focused on the potentially most interesting in practical point N-diphenylphosphorylureas – Ph2P(O)NHC(O)N. There has been established, that extraction abil ity of these phosphorylureas essentially depends on the nature of substituent at terminal nitrogen atom. Also, N-diphenyl-N’-n-alkyl(C6-C10)ureas Ph2P(O)NHC(O)NHCnH2n+1 (I, n = 6-10) possess high extraction ability in relation to uranium(VI), thorium(IV), americium(III) and to europium(III), and the greatest efficiency shows N’-n-octylurea (Ia). Meanwhile N-diphenylphosphoryl-N’ cyclooctylurea possessing enough high extraction ability in relation to uranium(VI), extracts euro pium(III) extremely bad. Similar behavior relative to this pair of elements exhibits N-diphenylphosphoryl-N’-(4-phenylbutyl)urea. It has unexpectedly appeared, that N diphenylphosphoryl-N’,N’-di-n-butylurea has low extraction ability in relation both to uranium(VI), and to europium(III). Influence on extraction ability of N-organophosphorylureas on the nature of substituent of phosphorus atom also has been studied. For this purpose synthesis of series of N’-n octylureas R(R’O)P(O)NHC(O)NHC8H17-n (where R = Me, Ph;
R’ = Et, Ph) has been carried out.
In all investigated cases it has appeared, that the replacement of one phenyl group at phosphorus atom on alkoxyl or aroxyl radical leads to sharp decrease of extraction ability of these ureas in rela tion to 4f- and to 5f-elements in comparison with diphenylphosphoryl analogue (Ia).
The opportunity of selective extraction of Eu(III) by urea (Ia) on a background of salts of other metals [Fe(III), Al(III), etc.], containing in significant amounts in LRW has been shown. On the basis of use of phosphorylurea (Ia) the scheme of division of six- and trivalent f-elements at extrac tion from nitrate medium is proposed.
This work is supported by RFBR (project number ¹ 05-03-08017-ofi_e) and Program # 8 of basic researches of Presidium of the Russian Academy of Science, Program “Development of methods of reception of chemical substances and creation of new materials“, subprogram “Development of organic synthesis methodology and formation of new organic compounds with valuable practical properties”. The project: “Development of methods of synthesis and study ing of properties of new mono- and polydentate organophosphorus compounds as applied to radioactive waste frac tionation processes“.
2534 ÕVIII Ìåíäåëååâñêèé ñúåçä ïî îáùåé è ïðèêëàäíîé õèìèè, Ìîñêâà, MICROBIOLOGICAL GAS PRODUSING IN THE DEEP REPOSITORY OF LIQUID RADIOACTIVE WASTES Safonov A.V.a, Savushkina M.K.a, Kosareva I.M.a, Ershov B.G.a, Nazina T.N.b a Institute of Microbiology of Russian Academy of Sciences, b Institute of Physical Chemistry of Russian Academy of Sciences, The problem of gas producing is very important for disposal of radioactive wastes in deep geologi cal formations for safety using and for temporary closing-down.
Investigations are carrying out for the second horizon of repository, situated at the depth of 190 210 meters and used for removal of low-level radioactive wastes.
Yearly samples of groundwater are collected, from wells located on the periphery or in the zone of penetration of wastes. The samples of formation waters are analysed for chemical and radio chemical components, acid-base characteristics and composition of dissolved and precipitated gases.
It was established early, that subsurface horizons of the repository “Severnyi” contain small but metabolically diverse microbial population, representing various physiological groups of microor ganisms, able to produce gases. This investigation is going on to the direction of: enumeration of bacteria, able to produce gases, studying the rates of sulphate reduction and methanogenesis, evaluation of impact of different physical-chemical conditions of repository (temperature, pH, salt concentrations, ionizing radiation) on biogenic gas producing.
Special emphasis is directed to studying denitrifying bacteria able to convert nitrate, one of mac rocomponent of the radioactive wastes, to nitrogen gas oxides and molecular nitrogen.
Established, that out of the periphery there was no changes in chemical, radiochemical and microbiological characteristics of ground water samples. In the zones of waste penetration there are modifications in chemical compounds and decrease the number and activity of microorganisms, that caused local gas appearance.