Zheleznogorsk, Russia
Zheleznogorsk, Russia

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Leshok D.Y.,Siberian Federal University | Alekseenko V.N.,Federal Center for Nuclear and Radiation Safety | Gavrilov P.M.,Mining and Chemical Combine | Alekseenko S.N.,Mining and Chemical Combine | And 4 more authors.
Radiochimica Acta | Year: 2015

Uranyl tris-(carbohydrazide) nitrate [UO2((N2H3)2CO)3](NO3)2 was prepared by the reaction of water solution of dioxouranium(VI) nitrate UO2(NO3)2(H2O)6 with ethanol solution of carbohydrazide (N2H3)2CO in a molar ratio of 1 to 3 in an neutral medium. The substance was characterized by elemental, thermal analysis and IR and 15N MAS CP NMR spectroscopy. Ab initio crystal structure determination was carried out using X-ray powder diffraction techniques. The compound crystallizes in monoclinic lattice with unit cell parameters: a = 15.193(1) Å, b = 12.005(1) Å, c = 10.842(1) Å, β = 109.15(1)°, V = 1868.11Å3, Z = 4, SG = Cc. The type of carbohydrazide coordination was additionally confirmed by 15N MAS CP NMR and IR spectroscopy. In the complex ion [UO2((N2H3)2CO)3]2+ three carbohydrazide ligands coordinate to UO22+ through oxygen and nitrogen forming three five-membered chelate rings. The carbohydrazide rings are tuned to the equatorial plane of complex. The crystal structure consists of zig-zag chains of [UO2((N2H3)2CO)3]2+ cations stretched along c-axis. The cations in the chain are linked by the hydrogen bonds between the cations themselves. The anions are located in the pores between chains and participate in hydrogen bonding between adjacent chains and additionally link the chain sections. The length of the chain section is 5.768Å and the angle between sections is 140°. The substance [UO2((N2H3)2CO)3](NO3)2 is thermally stable up to 215°C and then decomposes with an explosion. © 2015 Walter de Gruyter Berlin/Boston.

Volk V.I.,Russia Research Institute of Inorganic Materials | Veselov S.N.,Russia Research Institute of Inorganic Materials | Dvoeglazov K.N.,Russia Research Institute of Inorganic Materials | Arseenkov L.V.,Russia Research Institute of Inorganic Materials | And 3 more authors.
Atomic Energy | Year: 2016

New and modified technological and hardware solutions for reprocessing spent nuclear fuel from thermal reactors are described. The solutions developed form the foundation for a new technological scheme for reprocessing, termed the EKSKhROM-process. Verification data on the reprocessing of spent VVER-1000 fuel are presented and the characteristics of the products of reprocessing are presented. It is shown that the uranium and plutonium products are suitable for recycling in a closed nuclear fuel cycle. © 2016 Springer Science+Business Media New York

Antonenko M.V.,Mining and Chemical Combine | Chubreev D.O.,Mining and Chemical Combine | Kuznetsov G.V.,Tomsk Polytechnic University
Atomic Energy | Year: 2015

A mathematical model of the diffusion of radionuclides through engineered safety barriers is developed for 14C in order to determine the long-term safety conditions and characteristics of a decommissioned commercial uranium-graphite reactor. Dry and wet mixtures and concrete are used as the barrier materials. Diffusion is studied as the dominant mechanism for the transport of the radionuclides. The 14C concentration at the boundary between the radwaste storage site and the environment is determined computationally and the effect of the modeling conditions on the specific activity of the radionuclide is analyzed. The decomposition sequence of the safety barriers for which the 14C concentration is much lower than the admissible value is determined. © 2015 Springer Science+Business Media New York

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