Murataite-based ceramics for actinide waste immobilization

1999 ◽  
Vol 556 ◽  
Author(s):  
S. V. Stefanovsky ◽  
S. V. Yudintse ◽  
B. S. Nikonov ◽  
B. I. Omelianenko ◽  
A. G. Ptashkin
Keyword(s):  
Rare Earth ◽  
Chemical Durability ◽  
Isomorphic Substitution ◽  
Cold Crucible ◽  
Hydrothermal Conditions ◽  
High Chemical ◽  
Ceramic Samples ◽  
Waste Immobilization ◽  
Very High ◽  
Xrd And Tem

AbstractStudying the Synroc, doped with a simulated HLW, we have found, along with conventional Synroc phases (zirconolite, perovskite, hollandite), an extra phase with a stoichiornetry (Ca, Mn, U, TR)4(U, TR, Zr, Ti) 2(AI, Ti)7O22. XRD and TEM study has shown this phase is related to a very rare mineral murataite. In the present work a ceramic based on murataite is studied. The ceramic samples in the system: Ca-Mn-Ti-Zr-U-Ce-AI-Fe-O were produced and examined in details using XRD, SEM/EDS, TEM, and optical microscopy. Total amount of actinide (U) and rare earth (Ce, Gd) elements in the murataite exceeds 20 wt%. Isomorphic substitution schemes in the structures of synthetic and natural murataites are discussed. High isomorphic capacity of the murataite structure towards actinides and REEs, flexibility of its composition, feasibility of synthesis by melting, including a cold crucible melting, and very high chemical durability under hydrothermal conditions make the murataite-based ceramics very promising for actinides and excess weapon Pu fixation.

Synroc for Immobilising Excess Weapons Plutonium

1994 ◽  
Vol 353 ◽  
Author(s):  
A. Jostsons ◽  
E. R. Vance ◽  
D. J. Mercer ◽  
V. M. Oversby
Keyword(s):  
Chemical Durability ◽  
National Academy Of Sciences ◽  
Hydrothermal Conditions ◽  
Process Flowsheet ◽  
Disposal Option ◽  
Demonstration Plant ◽  
Deep Boreholes ◽  
Academy Of Sciences ◽  
High Degree ◽  
Very High

AbstractThe immobilisation of excess weapons plutonium into Synroc can meet all of the important criteria discussed by the U.S. National Academy of Sciences (NAS)(1) for disposal, if the disposal option is pursued rather than options that exploit the energy value of plutonium. This paper summarises the relevant background of Pu incorporation into Synroc, the durability of Pu-containing Synroc and outlines a process flowsheet based on the experience with the 10 kg/hr Synroc Demonstration Plant at ANSTO. The extensive solid solubility of Pu in Synroc, coupled with a very high degree of chemical durability under hydrothermal conditions, makes Synroc ideal as a waste matrix for Pu disposal in deep boreholes to minimise diversion and proliferation risks.

Application of Mechanical Activation for Production of Zirconate Pyrochlore Ceramic Containing Simulated Rare-Earth: Actinide Fraction of HLW

2003 ◽  
Author(s):  
S. V. Stefanovsky ◽  
S. V. Chizhevskaya ◽  
O. I. Kirjanova ◽  
N. S. Mikhailenko ◽  
B. S. Nikonov
Keyword(s):  
Mechanical Properties ◽  
Rare Earth ◽  
Mechanical Activation ◽  
Chemical Durability ◽  
Cold Pressing ◽  
Oxide Powders ◽  
Sintering Time ◽  
Ceramic Samples ◽  
Plasma Melting ◽  
Preliminary Mechanical Activation

Samples of zirconate pyrochlore ceramic (Ln)2(Zr,U)2O7 (Ln - lanthanides) containing simulated REE-An fraction of HLW were synthesized by conventional cold pressing of oxide mixtures in pellets under pressure of 200 MPa and sintering of pellets at 1550 °C for 24 hours and using preliminary mechanical activation of oxide powders for 5 or 10 min with a reduced sintering time for 6 hours. One more sample was produced by plasma melting. All the ceramic samples sintered at 1550 °C were monolithic and dense with high mechanically activated powders had higher chemical durability and mechanical properties.

Preparation of Calcium Phosphate Glasses Containing Nb2O5 and TiO2

2018 ◽  
Vol 782 ◽  
pp. 47-52
Author(s):  
Patrícia Suemi Sato ◽  
Hirotaka Maeda ◽  
Akiko Obata ◽  
Toshihiro Kasuga
Keyword(s):  
Controlled Release ◽  
Calcium Phosphate ◽  
Calcium Titanate ◽  
Chemical Durability ◽  
Phosphate Glasses ◽  
Dissolution Test ◽  
Buffer Solution ◽  
High Chemical ◽  
Positive Effects ◽  
Tris Buffer Solution

60CaO-30P2O5-(10 ̶ x)Nb2O5-xTiO2 (x = 0 ~ 10, mol%) glasses were prepared in order to obtain biomaterials with high chemical durability and therapeutic ions releasability. Dissolution test of these glasses using Tris buffer solution showed the controlled release of niobate ions from Nb2O5-containing glasses and the formation of calcium titanate in some of them. These behavior might induce positive effects for bone regeneration.

Microstructure and Electrical Properties of ZnO-Pr6O11-Dy2O3-Based Varistor Ceramics Doped with La2O3

2007 ◽  
Vol 336-338 ◽  
pp. 680-683
Author(s):  
Jing Nan Cai ◽  
Yuan Hua Lin ◽  
Rong Juan Zhao ◽  
Ce Wen Nan ◽  
Jin Liang He
Keyword(s):  
Rare Earth ◽  
Phase Composition ◽  
Electrical Properties ◽  
Rare Earth Elements ◽  
Leakage Current ◽  
Breakdown Voltage ◽  
Intergranular Phase ◽  
Ceramic Method ◽  
Sem Micrographs ◽  
Ceramic Samples

ZnO-Pr6O11-Dy2O3-based varistor ceramics doped with 0~1.5 mol% La2O3 were fabricated by a conventional ceramic method. All the samples were sintered at 1350 oCfor 2 h. The phase composition and microstructure of the ceramic samples have been investigated by XRD, SEM and EDS. The results of SEM micrographs indicated that the La2O3 additives can promote ZnO grain’s growth, and the rare earth elements dispersed mainly in the intergranular phase observed by EDS. The electrical properties of the samples determined by the V-I curves revealed that the breakdown voltage of samples decreases from 508 V/mm to about 100 V/mm with the increase of La2O3, and the nonlinear exponent also decreases from 20.2 to 13.2. The typical leakage current is about 10.2 μA for the sample doped with 0.5 mol% La2O3.

scholarly journals XRD and TEM analyses of a simulated leached rare earth ore deposit: Implications for clay mineral contents and structural evolution

2021 ◽  
Vol 225 ◽  
pp. 112728
Author(s):  
Xiongwei Jin ◽  
Lingkang Chen ◽  
Haixia Chen ◽  
Lian Zhang ◽  
Wenjing Wang ◽  
...  
Keyword(s):  
Rare Earth ◽  
Clay Mineral ◽  
Structural Evolution ◽  
Mineral Contents ◽  
Ore Deposit ◽  
Xrd And Tem

HIPed Tailored Pyrochlore-Rich Glass-Ceramic Waste Forms for the Immobilization of Nuclear Waste

2008 ◽  
Vol 1124 ◽  
Author(s):  
Melody Lyn Carter ◽  
Hui Li ◽  
Yingjie Zhang ◽  
Andrew L Gillen ◽  
Eric R Vance
Keyword(s):  
Nuclear Waste ◽  
Glass Ceramic ◽  
Glass Ceramics ◽  
Spectroscopic Characterization ◽  
Chemical Durability ◽  
Intermediate Level ◽  
Crystalline Phases ◽  
Waste Forms ◽  
Ceramic Samples

AbstractHot isostatically pressed (HIPed) glass-ceramics for the immobilization of uranium-rich intermediate-level wastes and Hanford K-basin sludges were designed. These were based on pyrochlore-structured Ca(1-x)U(1+y)Ti2O7 in glass, together with minor crystalline phases. Detailed microstructural, diffraction and spectroscopic characterization of selected glass-ceramic samples has been performed, and chemical durability is adequate, as measured by both MCC-1 and PCT-B leach tests.

Low Temperature Hydrothermal Synthesis of Nanophase BaTiO3 and BaFe12O19 Powders

1996 ◽  
Vol 457 ◽  
Author(s):  
Fatih Dogan ◽  
Shawn O'rourke ◽  
Mao-Xu Qian ◽  
Mehmet Sarikaya
Keyword(s):  
Particle Size ◽  
Hydrothermal Reaction ◽  
Average Particle Size ◽  
Reaction Times ◽  
Nanocrystalline Powders ◽  
Molar Ratio ◽  
Average Particle ◽  
Hydrothermal Conditions ◽  
Processing Variables ◽  
Xrd And Tem

ABSTRACTNanocrystalline powders with an average particle size of 50 nm has been synthesized in two materials systems under hydrothermal conditions below 100°C. Processing variables, such as temperature, concentration and molar ratio of reactants and reaction time were optimized to obtain particles of reduced size and stoichiometric compositions. Hydrothermal reaction takes place between Ba(OH)2 solution and titanium/iron precursors in sealed polyethylene bottles in the BaTiO3 and BaFe12O19 systems, respectively. While crystalline BaTiO3 forms relatively fast within a few hours, formation of fully crystalline and stoichiometric BaFei20i9 require considerably longer reaction times up to several weeks and strongly dependent on the Ba:Fe ratio of the precursors. The structural and compositional evaluation of the nanophase powders were studied by XRD and TEM techniques.

Nuclear Waste Immobilization by Vitrification in a Cold Crucible Melter: 3D Magnetic Model of a Melter

2008 ◽  
Vol 1107 ◽  
Author(s):  
A. Bonnetier
Keyword(s):  
Hydraulic Properties ◽  
Cold Crucible ◽  
Nuclear Facilities ◽  
Electromagnetic Design ◽  
Waste Vitrification ◽  
3D Geometry ◽  
Waste Immobilization ◽  
Magnetic Model ◽  
Nuclear Waste Immobilization ◽  
Physical Phenomena

AbstractThe design and development of prototype cold crucible melters for waste vitrification are based on models of the basic physical phenomena, including electromagnetic induction and the thermal and hydraulic properties in natural or forced convection. The complexity of new nuclearized facilities results in significant errors on the results of predictive models based on 2D axisymmetric geometry that can only be resolved by modeling the device in 3D geometry. This document discusses the specification and electromagnetic design of a melter carried out using electromagnetic computation software, FLU3D, developed in 3D geometry by Cedrat. The principles and results of this study are directly applicable to nuclear facilities with allowance for the particular requirements of a nuclearized environment.

The Performance of the Cold Crucible Melting of Refractory Materials

2005 ◽  
Author(s):  
B. T. Min ◽  
J. H. Song ◽  
S. H. Chung
Keyword(s):  
Computational Model ◽  
Computational Analysis ◽  
Refractory Materials ◽  
Cold Crucible ◽  
Electro Magnetic Field ◽  
High Melting Temperature ◽  
Pure Zirconia ◽  
Electro Magnetic ◽  
Computational Analyses ◽  
Very High

To investigate the performance of a cold crucible employed for the melting of refractory material, which has a very high melting temperature of about 3000 K, a computational analysis of the coupled electro-magnetic field, heat transfer, and fluid flow is carried out. Governing differential equations, basic numerical methods, computational model, and the results of the simulation of cold crucible melting are discussed. Computational Analyses were performed for the melting of corium, which is a mixture of UO2 and ZrO2, and pure zirconia. By comparing the analysis results with the experimental data, it is shown that the proposed computational model reasonably predicts the fundamental characteristics of a cold crucible melting.

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