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S. V. Yudintsev
Institute of Geology of Ore Deposits, Petrography, Mineralogy and Geochemistry of Russian Academy of Sciences (IGEM RAS), 119017 Moscow, Russia

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Review
Published: 07 April 2021 in Sustainability
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Glass crystalline materials (GCM) are of increasing interest as advanced nuclear wasteforms combining the advantages of vitreous and crystalline matrices. The GCM are versatile wasteforms envisaged for a wider use to immobilise various types of both radioactive and chemically hazardous wastes. They can be produced either via low temperature sintering using precursors composed of glass frit, oxides, and crystalline phases or through conventional melting aiming to produce first a parent glass, which is then crystallised by a controlled thermal schedule to obtain target crystalline phases within the GCM. Utilization of GCM is highlighted as a perspective wasteform for immobilization of partitioned radionuclide streams.

ACS Style

Michael Ojovan; Vladislav Petrov; Sergey Yudintsev. Glass Crystalline Materials as Advanced Nuclear Wasteforms. Sustainability 2021, 13, 4117 .

AMA Style

Michael Ojovan, Vladislav Petrov, Sergey Yudintsev. Glass Crystalline Materials as Advanced Nuclear Wasteforms. Sustainability. 2021; 13 (8):4117.

Chicago/Turabian Style

Michael Ojovan; Vladislav Petrov; Sergey Yudintsev. 2021. "Glass Crystalline Materials as Advanced Nuclear Wasteforms." Sustainability 13, no. 8: 4117.

Journal article
Published: 01 March 2019 in Doklady Earth Sciences
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It is suggested to dispose of radioactive wastes of nuclear energetics with long-lived actinides in the form of titanates and zirconates in boreholes up to 5 km deep. The low leaching rate of the waste imitator (Nd) from samples is shown during their interaction with chloride brine at 200°C. The elements in the liquid phase mostly occur in soluble form, and the role of their colloidal form is insignificant. Our results allow substantiation of a choice of promising materials for actinide immobilization.

ACS Style

S. V. Yudintsev; V. I. Malkovsky; M. S. Nikolsky; B. S. Nikonov. Interaction of Actinide Matrices with Brine. Doklady Earth Sciences 2019, 485, 303 -307.

AMA Style

S. V. Yudintsev, V. I. Malkovsky, M. S. Nikolsky, B. S. Nikonov. Interaction of Actinide Matrices with Brine. Doklady Earth Sciences. 2019; 485 (1):303-307.

Chicago/Turabian Style

S. V. Yudintsev; V. I. Malkovsky; M. S. Nikolsky; B. S. Nikonov. 2019. "Interaction of Actinide Matrices with Brine." Doklady Earth Sciences 485, no. 1: 303-307.

Journal article
Published: 01 December 2018 in Doklady Physics
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High temperature behavior of sodium–aluminum fluorophosphate glass—a potential matrix for immobilisation of waste salt electrolyte from pyrochemical reprocessing of irradiated nuclear fuel (INF) has been studied. The glass crystallizes between 430 and 640°C with formation of phosphate phases, which dissolve above 640°C leading to homogenization of the glass. Similar transformations of the glass matrix due to heating from the decay of short-lived fission products may have a negative effect on properties of vitrified radioactive chloride wastes during storage in a repository.

ACS Style

S. V. Yudintsev; A. A. Shiryaev. Thermal Stability of Glass with Simulators of Chloride Highly Radioactive Wastes. Doklady Physics 2018, 63, 513 -516.

AMA Style

S. V. Yudintsev, A. A. Shiryaev. Thermal Stability of Glass with Simulators of Chloride Highly Radioactive Wastes. Doklady Physics. 2018; 63 (12):513-516.

Chicago/Turabian Style

S. V. Yudintsev; A. A. Shiryaev. 2018. "Thermal Stability of Glass with Simulators of Chloride Highly Radioactive Wastes." Doklady Physics 63, no. 12: 513-516.

Journal article
Published: 01 April 2017 in Doklady Earth Sciences
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In Russia, highly radioactive liquid wastes from recycling of spent fuel of nuclear reactors are solidified into Na–Al–P glass for underground storage. The properties of the matrix including the radionuclide fixation will change with time due to crystallization. This is supported by the results of study of the interaction between glassy matrices, products of their crystallization, and water. The concentration of Cs in a solution at the contact of a recrystallized sample increased by three orders of magnitude in comparison with an experiment with glass. This difference is nearly one order of magnitude for Sr, Ce, and Nd (simulators of actinides) and U due to their incorporation into phases with low solubility in water. Based on data on the compositional change of solutions after passing through filters of various diameters, it is concluded that Cs occurs in the dissolved state in runs with a glass and recrystallized matrix. At the same time, Sr, lanthanides, and U occur in the dissolved state and in the composition of colloids in runs with glass, and mostly in colloid particles after contact with the recrystallized sample. These results should be regarded for substantiation of safety for geological waste storage.

ACS Style

S. V. Yudintsev; A. M. Pervukhina; A. V. Mokhov; V. I. Malkovsky; S. V. Stefanovsky. Influence of phosphate glass recrystallization on the stability of a waste matrix to leaching. Doklady Earth Sciences 2017, 473, 427 -432.

AMA Style

S. V. Yudintsev, A. M. Pervukhina, A. V. Mokhov, V. I. Malkovsky, S. V. Stefanovsky. Influence of phosphate glass recrystallization on the stability of a waste matrix to leaching. Doklady Earth Sciences. 2017; 473 (2):427-432.

Chicago/Turabian Style

S. V. Yudintsev; A. M. Pervukhina; A. V. Mokhov; V. I. Malkovsky; S. V. Stefanovsky. 2017. "Influence of phosphate glass recrystallization on the stability of a waste matrix to leaching." Doklady Earth Sciences 473, no. 2: 427-432.

Journal article
Published: 01 March 2017 in Doklady Earth Sciences
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Three groups of industrial uranium deposits that differ in the distribution of lanthanides in U oxides have been recognized. A dependence of the REE distribution type on the Yttrium content and Yttrium index YI = (La + Ce)/Y that controls the formation of REE phases capable of selective accumulation of lanthanides has been discovered. This indicates the important role of crystal–chemical fractionation in the distribution of lanthanides. Preferable accumulation of Sm–Gd by U oxides has been found to occur at relatively low contents of Y. In Proterozoic uranium deposits, the yttrium specialization of oxides predominates, while in most Phanerozoic deposits the lanthanum–cerium specialization is typical. These results extend the possibilities of using REEs in ores for purposes of study of the genesis of various uranium deposits.

ACS Style

S. F. Vinokurov; V. N. Golubev; A. N. Trunova; S. V. Yudintsev. Distribution of rare earths in uranium oxides of the main types of uranium deposits: Causes and genetic meaning. Doklady Earth Sciences 2017, 473, 281 -285.

AMA Style

S. F. Vinokurov, V. N. Golubev, A. N. Trunova, S. V. Yudintsev. Distribution of rare earths in uranium oxides of the main types of uranium deposits: Causes and genetic meaning. Doklady Earth Sciences. 2017; 473 (1):281-285.

Chicago/Turabian Style

S. F. Vinokurov; V. N. Golubev; A. N. Trunova; S. V. Yudintsev. 2017. "Distribution of rare earths in uranium oxides of the main types of uranium deposits: Causes and genetic meaning." Doklady Earth Sciences 473, no. 1: 281-285.

Journal article
Published: 01 February 2017 in Journal of the European Ceramic Society
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ACS Style

S.V. Stefanovsky; S.V. Yudintsev; A.A. Shiryaev; V.Y. Murzin; Alexander Trigub. Phase partitioning and uranium speciation in brannerite-based ceramics. Journal of the European Ceramic Society 2017, 37, 771 -777.

AMA Style

S.V. Stefanovsky, S.V. Yudintsev, A.A. Shiryaev, V.Y. Murzin, Alexander Trigub. Phase partitioning and uranium speciation in brannerite-based ceramics. Journal of the European Ceramic Society. 2017; 37 (2):771-777.

Chicago/Turabian Style

S.V. Stefanovsky; S.V. Yudintsev; A.A. Shiryaev; V.Y. Murzin; Alexander Trigub. 2017. "Phase partitioning and uranium speciation in brannerite-based ceramics." Journal of the European Ceramic Society 37, no. 2: 771-777.

Journal article
Published: 01 July 2016 in Radiochemistry
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ACS Style

S. V. Yudintsev; S. V. Stefanovsky; M. S. Nikol’Skii; O. I. Stefanovskaya; B. S. Nikonov. Brannerite, UTi2O6: Crystal chemistry, synthesis, properties, and use for actinide waste immobilization. Radiochemistry 2016, 58, 333 -348.

AMA Style

S. V. Yudintsev, S. V. Stefanovsky, M. S. Nikol’Skii, O. I. Stefanovskaya, B. S. Nikonov. Brannerite, UTi2O6: Crystal chemistry, synthesis, properties, and use for actinide waste immobilization. Radiochemistry. 2016; 58 (4):333-348.

Chicago/Turabian Style

S. V. Yudintsev; S. V. Stefanovsky; M. S. Nikol’Skii; O. I. Stefanovskaya; B. S. Nikonov. 2016. "Brannerite, UTi2O6: Crystal chemistry, synthesis, properties, and use for actinide waste immobilization." Radiochemistry 58, no. 4: 333-348.

Journal article
Published: 01 July 2016 in Doklady Earth Sciences
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ACS Style

S. V. Yudintsev; S. V. Tomilin; T. S. Livshits; A. A. Lizin; I. A. Goryatchev. Curium-doped stannate pyrochlore: Durability under radiation and leaching in water. Doklady Earth Sciences 2016, 469, 732 -736.

AMA Style

S. V. Yudintsev, S. V. Tomilin, T. S. Livshits, A. A. Lizin, I. A. Goryatchev. Curium-doped stannate pyrochlore: Durability under radiation and leaching in water. Doklady Earth Sciences. 2016; 469 (1):732-736.

Chicago/Turabian Style

S. V. Yudintsev; S. V. Tomilin; T. S. Livshits; A. A. Lizin; I. A. Goryatchev. 2016. "Curium-doped stannate pyrochlore: Durability under radiation and leaching in water." Doklady Earth Sciences 469, no. 1: 732-736.

Journal article
Published: 01 November 2015 in Radiochemistry
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ACS Style

S. V. Yudintsev; S. V. Stefanovsky; O. I. Stefanovskaya; B. S. Novikov; M. S. Nikol’Skii. Phase distribution of uranium in matrices for immobilization of the rare earth–actinide fraction of high-level waste. Radiochemistry 2015, 57, 640 -651.

AMA Style

S. V. Yudintsev, S. V. Stefanovsky, O. I. Stefanovskaya, B. S. Novikov, M. S. Nikol’Skii. Phase distribution of uranium in matrices for immobilization of the rare earth–actinide fraction of high-level waste. Radiochemistry. 2015; 57 (6):640-651.

Chicago/Turabian Style

S. V. Yudintsev; S. V. Stefanovsky; O. I. Stefanovskaya; B. S. Novikov; M. S. Nikol’Skii. 2015. "Phase distribution of uranium in matrices for immobilization of the rare earth–actinide fraction of high-level waste." Radiochemistry 57, no. 6: 640-651.

Journal article
Published: 01 May 2015 in Radiochemistry
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The structure of eight samples containing simulated rare earth–actinide fraction of high-level waste was studied. Samples of weight from 0.2 to 6 kg were prepared by cold crucible induction melting followed by crystallization of the melt. The target phases (britholite, pyrochlore, zirconolite, rhombic and monoclinic rare earth titanates) prevail in all the matrices; glass, zirconolite, and rutile were detected as impurities, sometimes in significant amounts. These phases do not contain waste components (rutile) or are stable in solutions (zirconolite); therefore, their presence should not impair the properties of the matrix. The possibility of controlling the phase composition of the matrix by introducing zirconium or aluminum oxide into the charge was demonstrated.

ACS Style

S. V. Yudintsev; S. V. Stefanovsky; M. Yu. Kalenova; B. S. Nikonov; M. S. Nikol’Skii; A. M. Koshcheev; A. S. Shchepin. Matrices for immobilization of the rare earth–actinide waste fraction, synthesized by cold crucible induction melting. Radiochemistry 2015, 57, 321 -333.

AMA Style

S. V. Yudintsev, S. V. Stefanovsky, M. Yu. Kalenova, B. S. Nikonov, M. S. Nikol’Skii, A. M. Koshcheev, A. S. Shchepin. Matrices for immobilization of the rare earth–actinide waste fraction, synthesized by cold crucible induction melting. Radiochemistry. 2015; 57 (3):321-333.

Chicago/Turabian Style

S. V. Yudintsev; S. V. Stefanovsky; M. Yu. Kalenova; B. S. Nikonov; M. S. Nikol’Skii; A. M. Koshcheev; A. S. Shchepin. 2015. "Matrices for immobilization of the rare earth–actinide waste fraction, synthesized by cold crucible induction melting." Radiochemistry 57, no. 3: 321-333.

Journal article
Published: 01 March 2015 in Doklady Earth Sciences
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The behavior of samples of A2B2O7 composition under irradiation with 1-MeV Kr2+ ions was studied (A is a simulator of the REE-actinide fraction of the wastes of the treatment of used nuclear fuel and B is a quadrivalent cation of Zr, Sn, or Ti). Depending on the B elements, the samples are crystallized either in pyrochlore (Zr and Sn) or in the perovskite structural type (Ti). The matrices of the pyrochlore structure are radiation-resistant, which is shown by their high critical doses and low critical temperatures of amorphization. The phases of monocline REE titanate structure are characterized by low irradiation resistance and should be amorphized even within centuries of storage. To characterize the possibilities of their usage as matrices for waste immobilization, synthesis of materials containing short-living actinides and studies of the degree of the amorphization effect on their stability in aqueous solutions are required.

ACS Style

S. V. Yudintsev; T. S. Livshits; Jiaming Zhang; Rodney C Ewing. The behavior of rare-earth pyrochlores and perovskites under ion irradiation. Doklady Earth Sciences 2015, 461, 247 -253.

AMA Style

S. V. Yudintsev, T. S. Livshits, Jiaming Zhang, Rodney C Ewing. The behavior of rare-earth pyrochlores and perovskites under ion irradiation. Doklady Earth Sciences. 2015; 461 (1):247-253.

Chicago/Turabian Style

S. V. Yudintsev; T. S. Livshits; Jiaming Zhang; Rodney C Ewing. 2015. "The behavior of rare-earth pyrochlores and perovskites under ion irradiation." Doklady Earth Sciences 461, no. 1: 247-253.

Journal article
Published: 01 March 2015 in Radiochemistry
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ACS Style

S. V. Yudintsev; S. V. Stefanovsky; B. S. Nikonov; M. S. Nikol’Skii; T. S. Livshits. Potential matrices for immobilization of the rare earth-actinide fraction of high-level waste in the REE2Zr2O7-REE2Ti2O7 system. Radiochemistry 2015, 57, 187 -199.

AMA Style

S. V. Yudintsev, S. V. Stefanovsky, B. S. Nikonov, M. S. Nikol’Skii, T. S. Livshits. Potential matrices for immobilization of the rare earth-actinide fraction of high-level waste in the REE2Zr2O7-REE2Ti2O7 system. Radiochemistry. 2015; 57 (2):187-199.

Chicago/Turabian Style

S. V. Yudintsev; S. V. Stefanovsky; B. S. Nikonov; M. S. Nikol’Skii; T. S. Livshits. 2015. "Potential matrices for immobilization of the rare earth-actinide fraction of high-level waste in the REE2Zr2O7-REE2Ti2O7 system." Radiochemistry 57, no. 2: 187-199.

Journal article
Published: 01 February 2015 in Doklady Earth Sciences
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The samples on the basis of Ln2Ti2O7 and Ln4Ti9O24 lanthanide titanates were obtained by compacting-sintering and melting-crystallization processes. The substances as such are promising as immobilizing matrices for the rare earth-actinide fraction of wastes of the treatment of used nuclear fuel. The content of simulators of the rare earth-actinide fraction in the obtained phases was as high as 50 mass % or more. The phases were characterized by a narrow range of variations of their composition. The admixtures of zirconium and aluminum caused the formation of zirconolite; the excess of titanium resulted in the formation of rutile or rhombic titanate (in the cases of Ln4Ti9O24 and Ln2Ti2O7, respectively). The use of these crystalline matrices for immobilization of long-lived radionuclides should provide a considerable decrease in the volume of solidified radioactive wastes to be disposed in deep-seated storage.

ACS Style

S. V. Yudintsev. Lanthanide titanates as promising matrices for immobilization of actinide wastes. Doklady Earth Sciences 2015, 460, 130 -136.

AMA Style

S. V. Yudintsev. Lanthanide titanates as promising matrices for immobilization of actinide wastes. Doklady Earth Sciences. 2015; 460 (2):130-136.

Chicago/Turabian Style

S. V. Yudintsev. 2015. "Lanthanide titanates as promising matrices for immobilization of actinide wastes." Doklady Earth Sciences 460, no. 2: 130-136.

Journal article
Published: 01 September 2012 in Radiochemistry
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The possibility of preparing by self-propagating high-temperature synthesis (SHS) metal-ceramic (cermet) matrices with simulated wastes of REE-actinide fraction and Tc was examined. The specimens consist of oxide crystalline phases, glass, and melts. In the aluminate composite, the component (Sm) simulating the REE-actinide fraction is in the garnet and glass phases, and in the titanate composite, in the pyrochlore, titanosilicate of perrierite structure, and glass phases. Rhenium (Tc simulator) is incorporated in alloy phases. To evaluate the prospects for radioactive waste immobilization by SHS, it is necessary to synthesize matrices containing actinide isotopes (Am) and Tc and to study their structure and isolation properties.

ACS Style

N. P. Laverov; S. V. Yudintsev; E. E. Konovalov; M. S. Nikol’Skii; T. O. Mishevets; B. S. Nikonov; B. I. Omel’Yanenko. Self-propagating high-temperature synthesis and characteristics of cermet matrices for isolation of wastes with long-lived radionuclides. Radiochemistry 2012, 54, 511 -515.

AMA Style

N. P. Laverov, S. V. Yudintsev, E. E. Konovalov, M. S. Nikol’Skii, T. O. Mishevets, B. S. Nikonov, B. I. Omel’Yanenko. Self-propagating high-temperature synthesis and characteristics of cermet matrices for isolation of wastes with long-lived radionuclides. Radiochemistry. 2012; 54 (5):511-515.

Chicago/Turabian Style

N. P. Laverov; S. V. Yudintsev; E. E. Konovalov; M. S. Nikol’Skii; T. O. Mishevets; B. S. Nikonov; B. I. Omel’Yanenko. 2012. "Self-propagating high-temperature synthesis and characteristics of cermet matrices for isolation of wastes with long-lived radionuclides." Radiochemistry 54, no. 5: 511-515.

Journal article
Published: 23 June 2011 in Radiochemistry
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Matrices for actinide wastes, consisting of complex murataite-type oxides, were studied. The samples were prepared by sintering of the oxide charge at 1100–1400°C or by fusion at 1450–1600°C followed by crystallization. Along with the structural analog of the natural mineral (murataite 3C), appreciable role in the samples is played by the phases (hereinafter murataites 5C, 7C, and 8C) consisting of pyrochlore and murataite 3C units. The fraction of wastes in the samples is about 10 wt %, which is close to the values for the pyrochlore matrix for Pu immobilization. In the ceramics prepared from the melt, the murataite grains have a zonal structure. They are built of murataite 3C at edges and murataite 5C (rarely 7C) in the center where the actinide content is maximal. This fact accounts for their high capability to isolate radionuclides. Amorphization of the structure only slightly affects the stability of murataite in solution. The optimal procedure for the industrial production of the matrices is their melting by induction heating in cold crucible (IMCC) and crystallization.

ACS Style

N. P. Laverov; S. V. Yudintsev; S. V. Stefanovskii; B. I. Omel’Yanenko; B. S. Nikonov. Murataite matrices for actinide wastes. Radiochemistry 2011, 53, 229 -243.

AMA Style

N. P. Laverov, S. V. Yudintsev, S. V. Stefanovskii, B. I. Omel’Yanenko, B. S. Nikonov. Murataite matrices for actinide wastes. Radiochemistry. 2011; 53 (3):229-243.

Chicago/Turabian Style

N. P. Laverov; S. V. Yudintsev; S. V. Stefanovskii; B. I. Omel’Yanenko; B. S. Nikonov. 2011. "Murataite matrices for actinide wastes." Radiochemistry 53, no. 3: 229-243.

Journal article
Published: 01 January 2010 in Geochemistry International
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Complex oxides of the pyrochlore (space groups Fd3m, [8]A2 [6]B2O7) and garnet (Ia3d, [8]A3 [6]B2 [4]T3O12) structures (“A” = Ca2+, Ln3+/4+, An3+/4+; “B” = (Ti, Sn, Hf, and Zr)4+ in pyrochlore, and Al3+, Ga3+, and Fe3+ in garnet alone; “T” = (Al3+, Ga3+, and Fe3+) are promising matrices for actinide-bearing wastes. In order to identify optimal compositions of these phases, their isomorphic capacity with respect to REE, actinides, and other components of wastes was examined. The long-term behavior of the matrix at a repository was predicted based on data obtained on the behavior of pyrochlores and garnets under ion irradiation and 244Cm decay and on the determined leaching rates of REE from the matrices because of their interaction with aqueous solutions, including that after amorphization. In order to propose efficient synthesis techniques, samples prepared with the use of various methods were studied. The possibility of incorporating long-lived decay products of 99Tc into the crystalline matrices was analyzed.

ACS Style

N. P. Laverov; S. V. Yudintsev; T. S. Livshits; S. V. Stefanovsky; A. N. Lukinykh; R. C. Ewing. Synthetic minerals with the pyrochlore and garnet structures for immobilization of actinide-containing wastes. Geochemistry International 2010, 48, 1 -14.

AMA Style

N. P. Laverov, S. V. Yudintsev, T. S. Livshits, S. V. Stefanovsky, A. N. Lukinykh, R. C. Ewing. Synthetic minerals with the pyrochlore and garnet structures for immobilization of actinide-containing wastes. Geochemistry International. 2010; 48 (1):1-14.

Chicago/Turabian Style

N. P. Laverov; S. V. Yudintsev; T. S. Livshits; S. V. Stefanovsky; A. N. Lukinykh; R. C. Ewing. 2010. "Synthetic minerals with the pyrochlore and garnet structures for immobilization of actinide-containing wastes." Geochemistry International 48, no. 1: 1-14.

Conference paper
Published: 01 January 2010 in MRS Proceedings
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The blocks of glassy material at 55 wt.% SB4 waste loading produced in a demountable cold crucible and cooled to room temperature in cold crucible and glasses cooled in a resistive furnace by a canister centerline cooling (CCC) regime were sectioned to investigate phase composition and elemental distribution between various parts of the blocks. X-ray diffraction (XRD), optical microscopy, scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS) and infrared (IR) spectroscopy studies revealed some difference in the texture but not in phase composition of the materials sampled from various parts of the blocks. The glass samples were composed of vitreous and spinel structure phases. Spinel was present as both skeleton-type aggregates of fine (micron- or submicron-sized) crystals segregated at early stages of melt solidification and larger (up to tens of microns) individual more regular crystals formed during slow melt cooling. There was some tendency for elemental segregation in the glass block from the cold crucible with enrichment of the deeper zones with heavier transition metal ions and depletion of Na, Cs, Ca, Al and Si. Uranium was quite uniformly distributed within zones of the block and entered the vitreous phase.

ACS Style

Sergey Stefanovsky; Boris Nikonov; Boris Omelianenko; James C Marra. Phase Composition and Elemental Distribution in the Vitrified U-bearing HLW Surrogate. MRS Proceedings 2010, 1265, 1 .

AMA Style

Sergey Stefanovsky, Boris Nikonov, Boris Omelianenko, James C Marra. Phase Composition and Elemental Distribution in the Vitrified U-bearing HLW Surrogate. MRS Proceedings. 2010; 1265 ():1.

Chicago/Turabian Style

Sergey Stefanovsky; Boris Nikonov; Boris Omelianenko; James C Marra. 2010. "Phase Composition and Elemental Distribution in the Vitrified U-bearing HLW Surrogate." MRS Proceedings 1265, no. : 1.

Journal article
Published: 01 August 2009 in Geology of Ore Deposits
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Amongst fission products formed in atomic reactors, 99Tc is the most hazardous for the environment because of its long half-life (213000 yr), high content in spent nuclear fuel (SNF) (0.8–1.0 kg per ton of SNF), low sorption ability, and high mobility under aerobic conditions. The bulk of 99Tc (∼200 t) is incorporated into SNF. In the course of SNF reprocessing, this radioisotope is released as a separate fraction or along with actinides. More than 60 t of highly concentrated 99Tc have been accumulated to date. It is evident that isolation of 99Tc from the environment is a matter of great urgency. The immobilization of technetium in a highly stable and poorly soluble matrix is a necessary element in settling this problem. Ceramics composed of titanates with pyrochlore, perovskite, and rutile structures are proposed as matrices able to retain technetium along with actinides. The high chemical stability of these compounds has been corroborated by experiments. The difficulties in production of such matrices are related to the fugacity of Tc and the necessity of converting it into Tc(IV). To overcome this obstacle, self-propagating high-temperature synthesis (SHS), characterized by reductive conditions and a high reaction rate, is proposed. The charge for matrix synthesis consists of reducing agents (metallic powders with a strong affinity to oxygen, e.g., Ti and Zr), oxidants (MoO3, Fe2O3, CuO), and additives (TiO2, ZrO2, Y2O3, CaO, etc.), which taken together with other elements form target phases. Instead of Tc, Mo, close in chemical properties, is used in matrix synthesis as a simulator. Samples of Mo-bearing matrices have been synthesized with SHS; their phase compositions and Mo distribution therein are characterized. It has been shown that up to 40 wt % Mo can be incorporated into the synthesized matrices in the form of metal or structural admixtures in titanates. The titanate-zirconate pyrochlore-based matrices are the most appropriate for the joint immobilization of actinides, REEs, and 99Tc.

ACS Style

N. P. Laverov; S. V. Yudintsev; B. I. Omel’Yanenko. Isolation of long-lived technetium-99 in confinement matrices. Geology of Ore Deposits 2009, 51, 259 -274.

AMA Style

N. P. Laverov, S. V. Yudintsev, B. I. Omel’Yanenko. Isolation of long-lived technetium-99 in confinement matrices. Geology of Ore Deposits. 2009; 51 (4):259-274.

Chicago/Turabian Style

N. P. Laverov; S. V. Yudintsev; B. I. Omel’Yanenko. 2009. "Isolation of long-lived technetium-99 in confinement matrices." Geology of Ore Deposits 51, no. 4: 259-274.

Book chapter
Published: 14 March 2008 in Minerals as Advanced Materials I
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The reprocessing of irradiated fuel of nuclear power plants results in the formation of a great amount of radioactive wastes, including high-level radioactive wastes (HLW). Selection of suitable immobilizing materials is a key part of safe HLW management in the nuclear fuel cycle. The search for confinement matrices began in the 1950s with study of various glassy and crystalline materials containing silicates, phosphates, and titanates (Ewing and Lutze 1988). Only borosilicate and alumophosphate glasses are used for this purpose on an industrial scale (Hench et al. 1984; Vashman et al. 1997). These glasses are not capable of incorporating sufficient amounts of actinides (particularly, Pu) and have low resistance to chemical corrosion by water (Matzke and van Geel 1996; Laverov et al. 1997). Interaction of the vitreous matrices with underground waters will result in the formation of colloidal particles (Glass as a waste form ... 1996), which can carry actinides for very long distances. The glasses also easily crystallize on aging (Vashman et al. 1997), which significantly decreases stability of the waste forms due to appearance of various soluble phases, such as alkali and alkaline-earth silicates, phosphates, and molybdates.

ACS Style

Tatiana Livshits; Sergey Yudintsev. Natural and Synthetic Minerals — Matrices (Forms) for Actinide Waste Immobilization. Minerals as Advanced Materials I 2008, 193 -207.

AMA Style

Tatiana Livshits, Sergey Yudintsev. Natural and Synthetic Minerals — Matrices (Forms) for Actinide Waste Immobilization. Minerals as Advanced Materials I. 2008; ():193-207.

Chicago/Turabian Style

Tatiana Livshits; Sergey Yudintsev. 2008. "Natural and Synthetic Minerals — Matrices (Forms) for Actinide Waste Immobilization." Minerals as Advanced Materials I , no. : 193-207.

Journal article
Published: 01 October 2006 in Geology of Ore Deposits
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A new variety of matrices based on synthetic phases whose structure is close to that of murataite (a natural mineral) is proposed for immobilization of nuclear wastes. Murataite is Na, Ca, REE, Zn, and Nb titanate with a structure derived from the fluorite lattice. This very rare mineral was found in alkali pegmatites from Colorado in the United States and the Baikal region in Russia. The synthetic murataite-like phases contain manganese instead of zinc, as well as actinides and zirconium instead of sodium, calcium, and niobium. Varieties with threefold, as in the mineral, and five-, seven-, and eightfold repetition of the lattice relative to the fluorite cell have been established. Correspondingly, the structural varieties M3, M5, M7, and M8 are recognized among the synthetic murataites. A decrease in the contents of actinides, rare earth elements, and zirconium occurs in the series M7-M5-M8-M3, along with enrichment in Ti, Al, Fe, and Ga. Murataite-based ceramics are characterized by high chemical and radiation stability. The rate of U, Th, and Pu leaching with water at 90°C in static and dynamic tests is 10−6–10−5 g/m2 per day. These values are lower than the leaching rate of other actinide confinement matrices, for example, zirconolite-or pyrochlore-based. Murataite is close to other titanates in its radiation resistance. At 25°C, amorphization of its lattice is provided by a radiation dose of 2 × 1018 α decays/g, or 0.2 displacements/atom. Murataite-based matrices are synthesized within a few hours by cold compacting combined with sintering at 1300°C or by melting at 1500–1600°C and subsequent crystallization. The melting technology, including induction smelters with a cold crucible, makes it possible to produce samples with zonal murataite grains. The inner zone of such grains is composed of structural variety M5 or M7; the intermediate zone, of M8; and the outer zone, of M3. The contents of actinides, zirconium, and rare earth elements reach a maximum in the inner zone and drop to a minimum in the outer zone, while the amounts of nonradioactive elements—Ti, Al, Fe, and Ga—vary conversely. The U, Th, and Pu contents in the inner and outer zones differ by three to five times. Such a distribution precludes removal of actinides by interaction of the matrix with solution after its underground disposal. Individual actinides (Np, Pu, Am); the actinide-zirconium-rare earth fraction of high-level radioactive wastes (HLW); Am-Ga residues of weapons plutonium reprocessing with its conversion into U-Pu mixed oxide (MOX) fuel; and other sorts of HLW enriched in actinides, REE, and products of corrosion (Mn, Fe, Al, Zr) can be incorporated into a murataite-based matrix. As much as 350 kg of HLW components can be included in 1 t of such a ceramic. An actinide matrix that is composed of titanates with a pyrochlore structure is its nearest analogue. The advantage of murataite in comparison with pyrochlore consists in its universal character; i.e., a murataite-based matrix can be used for utilization of a wider range of actinide-bearing highly radioactive wastes.

ACS Style

N. P. Laverov; S. V. Yudintsev; S. V. Stefanovsky; B. I. Omel’Yanenko; B. S. Nikonov. Murataite as a universal matrix for immobilization of actinides. Geology of Ore Deposits 2006, 48, 335 -356.

AMA Style

N. P. Laverov, S. V. Yudintsev, S. V. Stefanovsky, B. I. Omel’Yanenko, B. S. Nikonov. Murataite as a universal matrix for immobilization of actinides. Geology of Ore Deposits. 2006; 48 (5):335-356.

Chicago/Turabian Style

N. P. Laverov; S. V. Yudintsev; S. V. Stefanovsky; B. I. Omel’Yanenko; B. S. Nikonov. 2006. "Murataite as a universal matrix for immobilization of actinides." Geology of Ore Deposits 48, no. 5: 335-356.