Federal Center for Nuclear and Radiation Safety

Moscow, Russia

Federal Center for Nuclear and Radiation Safety

Moscow, 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.

Alekseenko V.N.,Federal Center for Nuclear and Radiation Safety | Dvoeglazov K.N.,HIGH-TECH | Marchenko V.I.,HIGH-TECH | Alekseenko S.N.,Federal State Unitary Enterprise | And 2 more authors.
Journal of Radioanalytical and Nuclear Chemistry | Year: 2015

The possibility of using carbohydrazide as a reducing agent for plutonium in Purex process was examined. Kinetics of the reaction between Pu(IV) and carbohydrazide in HNO3 aqueous solution was studied spectrophotometrically, the rate law was established, and the rate constant and activation energy values were calculated. Plutonium stripping efficiency by carbohydrazide as defined is higher in the two-phase system: 30 % TBP with Pu(IV) nitric acid aqueous solution, in the presence of glycine. A laboratory scale counter-current experiment performed with the use of simulated WWER-1000 SNF reprocessing solutions demonstrated the possibility of carbohydrazide–glycine mixture using for plutonium concentrating back-extraction process. © 2015, Akadémiai Kiadó, Budapest, Hungary.

Mazokin V.A.,Moscow Power Engineering Institute | Vasilyev A.P.,Moscow Power Engineering Institute | Vasukhno V.P.,Moscow Power Engineering Institute | Shishkin V.A.,Moscow Power Engineering Institute | Pimenov A.O.,Federal Center for Nuclear and Radiation Safety
Atomic Energy | Year: 2012

The results of an analysis of the salvaging of nuclear submarines and rehabilitation of radiation hazardous objects are presented. The principal design and technological problems and nuclear, radiation and ecological safety control as well as innovative technologies for handling spent fuel on naval objects are examined. The results of the R&D work and the main problems for the upcoming period are presented. © 2012 Springer Science+Business Media New York.

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

Marchenko V.I.,HIGH-TECH | Alekseenko V.N.,Federal Center for Nuclear and Radiation Safety | Dvoeglazov K.N.,HIGH-TECH
Radiochemistry | Year: 2015

Scientific, technical, and patent information on the use of organic compounds as reductants of Pu and Np ions in wet technology for spent nuclear fuel reprocessing is summarized and correlated. Organic derivatives of hydrazine and hydroxylamine, and also oximes and urea derivatives at relatively low acidities and temperatures reduce Np(VI) to Np(V) and Pu(IV) to Pu(III). As the acidity and temperature are increased, Np(V) is slowly reduced to Np(IV). Alcohols, aldehydes, hydrocarbons, and acetic acid were identified among products of oxidation of the organic compounds in nitric acid medium. The above-named organic reductants can be used in different steps of the PUREX process: separation of Pu and Np from U in the first extraction cycle, purification of U to remove Np in the second cycle of uranium purification, and Pu stripping in the step of its final purification. Laboratory experiments performed on countercurrent extraction installations of mixer-settlers and of centrifugal contactors demonstrated the possibility of reaching high separation factors of U from Pu and/or Np and high degrees of plutonium concentration to obtain Pu strips containing up to 150 g L-1 Pu. © 2015 Pleiades Publishing, Inc.

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