scholarly journals Bitumen Coating as a Tool for Improving the Porosity and Chemical Stability of Simulated Cement-Waste Forms

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
H. M. Saleh
Keyword(s):  
Experimental Tests ◽  
Waste Form ◽  
X Ray Diffraction ◽  
Microscope Examination ◽  
X Ray ◽  
Bitumen Emulsion ◽  
Waste Forms ◽  
Surrounding Environment ◽  
Simulated Waste ◽  
Physical And Chemical

Coating of simulated cement-based waste form was investigated by performing physical and chemical experimental tests. Moreover, X-ray diffraction, Fourier transform infrared spectroscopy, and electron microscope examination were applied on coated and noncoated simulated waste forms. Experimental results indicated that coating process improved the characterizations of cement-based waste form such as porosity and leachability. Diffusion coefficients and leach indecies of coated specimens were calculated and showed acceptable values. It could be stated that by coating cemented-waste form by bitumen emulsion, the radioactive contaminants were isolated, thus reducing the back release to surrounding environment during flooding by groundwater and consequently, saving the environment.

Rietveld Analysis of Ceramic Nuclear Waste Forms

1993 ◽  
Vol 333 ◽  
Author(s):  
T.J. White ◽  
H. Mitamura
Keyword(s):  
Rietveld Method ◽  
Amorphous Material ◽  
Rietveld Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Waste Forms ◽  
Simulated Waste ◽  
Diffraction Patterns ◽  
Nuclear Waste Forms ◽  
Selection Of

ABSTRACTPowder X-ray diffraction patterns were collected from three titanate waste forms - a calcine powder, a prototype ceramic without waste, and a ceramic containing 10 wt% JW-A simulated waste - and interpreted quantitatively using the Rietveld method. The calcine consisted of fluorite, pyrochlore, rutile, and amorphous material. The prototype waste form contained rutile, hollandite, zirconolite and perovskite. The phase constitution of the JW-A ceramic was freudenbergite, loveringite, hollandite, zirconolite, perovskite and baddeleyite. Procedures for the collection of X-ray data are described, as are assumptions inherent in the Rietveld approach. A selection of refined crystal data are presented.

Monitoring of Fluctuations in the Physical and Chemical Properties of a High-Calcium Fly Ash

1987 ◽  
Vol 113 ◽  
Author(s):  
Scott Schlorholtz ◽  
Ken Bergeson ◽  
Turgut Demirel
Keyword(s):  
Fly Ash ◽  
Chemical Properties ◽  
Operating Conditions ◽  
Physical And Chemical Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Morphological Studies ◽  
High Calcium ◽  
Physical And Chemical ◽  
And Chemical Properties

ABSTRACTThe physical and chemical properties of fly ash produced at Ottumwa Generating Station have been monitored since April, 1985. The fly ash is produced from burning a low sulfur, sub-bituminous coal obtained from the Powder River Basin near Gillette, Wyoming. One-hundred and sixty samples of fly ash were obtained during the two year period. All of the samples were subjected to physical testing as specified by ASTM C 311. About one-hundred of the samples were also subjected to a series of tests designed to monitor the self-cementing properties of the fly ash. Many of the fly ash samples were subjected to x-ray diffraction and fluorescence analysis to define the mineralogical and chemical composition of the bulk fly ash as a function of sampling date. Hydration products in selected hardened fly ash pastes, were studied by x-ray diffraction and scanning electron microscopy. The studies indicated that power plant operating conditions influenced the compressive strength of the fly ash paste specimens. Mineralogical and morphological studies of the fly ash pastes indicated that stratlingite formation occurred in the highstrength specimens, while ettringite was the major hydration product evident in the low-strength specimens.

Fabrication of 239/238Pu-Zirconolite Ceramic Pellets by Natural Sintering

2003 ◽  
Vol 807 ◽  
Author(s):  
T. Advocat ◽  
F. Jorion ◽  
T. Marcillat ◽  
G. Leturcq ◽  
X. Deschanels ◽  
...  
Keyword(s):  
Grain Size ◽  
Radioactive Waste ◽  
Nuclear Waste ◽  
Chemical Stability ◽  
Minor Actinides ◽  
Loading Capacity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Physical And Chemical ◽  
Inorganic Matrix

ABSTRACTZirconolite is a potential inorganic matrix that is currently investigated in France, in the framework of the 1991 radioactive waste management law, with a view to provide durable containment of the trivalent and tetravalent minor actinides like neptunium, curium, americium and small quantities of unrecyclable plutonium separated from other nuclear waste. To confirm the actinide loading capacity of the zirconolite calcium site and to study the physical and chemical stability of this type of ceramic when subjected to alpha self-irradiation, zirconolite ceramic pellets were fabricated with 10 wt% plutonium oxide (isotope 239 or 238). The 55 pellets are dense (> 93.3% of the theoretical density on average) and free of cracks. They are characterized by a grain size of between 10 and 20 micrometers. X-ray diffraction analyses confirmed the presence of the zirconolite 2M crystalline structure.

Host Phases for Actinide Elements in the Metallic Waste Form

2002 ◽  
Vol 757 ◽  
Author(s):  
D. E. Janney
Keyword(s):  
Stainless Steel ◽  
Electron Microscope ◽  
Electron Diffraction ◽  
Transmission Electron Microscope ◽  
Waste Form ◽  
Dissolution Behavior ◽  
Release Rates ◽  
Waste Forms ◽  
Transmission Electron ◽  
Simulated Waste

ABSTRACTArgonne National Laboratory has developed an electrometallurgical process for conditioning spent sodium-bonded metallic reactor fuel prior to disposal. A waste stream from this process consists of stainless steel cladding hulls that contain undissolved metal fission products such as Tc, Ru, Rh, Pd, and Ag; a small amount of undissolved actinides (U, Np, Pu) also remains with the hulls. These wastes will be immobilized in a waste form whose baseline composition is stainless steel alloyed with 15 wt% Zr (SS-15Zr). Scanning electron microscope (SEM) observations of simulated metal waste forms (SS-15Zr with up to 11 wt% actinides) show eutectic intergrowths of Fe-Zr-Cr-Ni intermetallic phases with steels. The actinide elements are almost entirely in the intermetallics, where they occur in concentrations ranging from 1–20 at%. Neutron- and electron-diffraction studies of the simulated waste forms show materials with structures similar to those of Fe2Zr and Fe23Zr6.Dissolution experiments on simulated waste forms show that normalized release rates of U, Np, and Pu differ from each other and from release rates of other elements in the sample, and that release rates for U exceed those for any other element (including Fe). This paper uses transmission electron microscope (TEM) observations and results from energy-dispersive X-ray spectroscopy (EDX) and selected-area electron-diffraction (SAED) to characterize relationships between structural and chemical data and understand possible reasons for the observed dissolution behavior.Transmission electron microscope observations of simulated waste form samples with compositions SS-15Zr-2Np, SS-15Zr-5U, SS-15Zr-11U-0.6Rh-0.3Tc-0.2Pd, and SS-15Zr-10Pu suggest that the major actinide-bearing phase in all of the samples has a structure similar to that of the C15 (cubic, MgCu2-type) polymorph of Fe2Zr, and that materials with this structure exhibit significant variability in chemical compositions. Material whose structure is similar to that of the C36 (dihexagonal, MgNi2-type) polymorph of Fe2Zr was also observed, and it exhibits less chemical variability than that displayed by material with the C15 structure. The TEM data also demonstrate a range of actinide concentrations in materials with the Fe23Zr6 (cubic, Mn23Th6-type) structure.Microstructures similar to those produced during experimental deformation of Fe-10 at% Zr alloys were observed in intermetallic materials in all of the simulated waste form samples. Stacking faults and associated dislocations are common in samples with U, but rarely observed in those with Np and Pu, while twins occurred in all samples. The observed differences in dissolution behavior between samples with different actinides may be related to increased defect-assisted dissolution in samples with U.

scholarly journals Study of Chemical and Morphological Transformations during Ni2Mo3N Synthesis via an Oxide Precursor Nitration Route

Catalysts ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 436
Author(s):  
Denis Leybo ◽  
Dmitry Arkhipov ◽  
Konstantin Firestein ◽  
Denis Kuznetsov
Keyword(s):  
Weight Changes ◽  
X Ray Diffraction ◽  
X Ray ◽  
Oxide Precursor ◽  
Nitride Formation ◽  
Extended Surface ◽  
Temperature Programmed ◽  
Morphological Transformations ◽  
Physical And Chemical ◽  
Oxide Sample

Chemical and morphological transformations during Ni2Mo3N synthesis were studied in this work. Nitride samples were synthesized from oxide precursors in H2/N2 flow and were analyzed by thermogravimetry, X-ray diffraction analysis, scanning electron microscopy, and energy dispersive X-ray spectroscopy methods. In addition, physical and chemical adsorption properties were studied using low-temperature N2 physisorption and NH3 temperature-programmed desorption. It was shown that nitride formation proceeds through a sequence of phase transformations: NiMoO4 + MoO3 → Ni + NiMo + MoO2 → Ni + NiMo + Mo2N → Ni2Mo3N. The weight changes that were calculated from the proposed reactions were in agreement with the experimental data from thermogravimetry. The morphology of the powder changed from platelets and spheres for the oxide sample, to aggregates of needle-like particles for the intermediate product, to porous particles with an extended surface area for the nitride final product. The obtained results should prove useful for subsequent Ni2Mo3N based catalysts production process optimization.

Characterization of Shivirtui Zeolite Modified with Aluminum Oxyhydroxide Nanofibers

2019 ◽  
Vol 942 ◽  
pp. 40-49
Author(s):  
Yulia Murashkina ◽  
Olga B. Nazarenko
Keyword(s):  
Chemical Properties ◽  
Nitrogen Adsorption ◽  
X Ray Diffraction ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
X Ray ◽  
Physical And Chemical ◽  
And Chemical Properties ◽  
Aluminum Oxyhydroxide

Natural zeolite of Shivirtui deposit (Russia) was modified with nanofibers of aluminum oxyhydroxide AlOOH. Aluminum oxyhydroxide nanofibers were produced at the heating and oxidation of aluminum powder with water. The properties of modified zeolite were investigated by means of X-ray diffraction, transmission electronic microscopy, scanning electronic microscopy, low-temperature nitrogen adsorption, thermal analysis, and Fourier transform infrared spectroscopy. It was found that water content in the modified sample of zeolite was about 15 %. Based on the study of the physical and chemical properties, shivirtui zeolite modified with nanofibers of aluminum oxyhydroxide can be proposed for use as a flame-retardant additive to polymers.

Electric Resistivity as Phase Volume Fractions Indicator in Metastable Alloys

2013 ◽  
Vol 738-739 ◽  
pp. 56-61
Author(s):  
Luc Saint Sulpice ◽  
Mohamed Lakrit ◽  
Shabnam Arbab Chirani ◽  
Sylvain Calloch
Keyword(s):  
Volume Fraction ◽  
Experimental Tests ◽  
Transformation Kinetic ◽  
Stress And Strain ◽  
Electric Resistance ◽  
Thermomechanical Loading ◽  
X Ray Diffraction ◽  
X Ray ◽  
History Of ◽  
Metastable Alloys

The microstructure of metastable alloys varies with the thermomechanical history of the material. During a thermomechanical loading, different phases can be present in the material simultaneously. They can be at the origin of macroscopic stress and strain. Consequently, it is important to determine the proportion of each phase to understand the transformation kinetic. However, the techniques usually used to carry out these measurements such as magnetic properties measurements, neutron or X-ray diffraction, are heavy and require a lot of resources. This study, thanks to experimental tests based on electric resistance measurements, permits to determine the volume fraction of the different states present in the material. The study has been realized on a 301 stainless steel in order to take into account the effects of elasticity, transformation and plasticity. Then the volume fraction of the different phases of the material has been determined during transformation with the plasticity presence.

Mineralogy and Physical and Chemical Characteristics of Coal Ash from Yang Zonghai Power Plant

2010 ◽  
Vol 177 ◽  
pp. 497-501
Author(s):  
Feng Rui Zhai ◽  
Zhong Zhou Yi ◽  
Qun Cai ◽  
Huan Bin Song ◽  
Li Li Zhang ◽  
...  
Keyword(s):  
Power Plant ◽  
Particle Diameter ◽  
Coal Ash ◽  
Chemical Characteristics ◽  
Test Results ◽  
X Ray Diffraction ◽  
X Ray ◽  
Physical And Chemical Characteristics ◽  
Coal Ashes ◽  
Physical And Chemical

The modality, physical and chemical characteristics, mineralogy and distribution of particle size of coal ash were studied by modern analytic technology SEM, spectral analysis, X - ray Diffraction (XRD) and laser granularity analyzer. The test results show that the mineralogy of coal ashes is dominated mainly by mullite, quartz and hematite.The coal ash of Yang Zonghai power plant has lower content of calcium oxide and is low calcium ash.At the same time, the losing amount is low to burn.The particle diameter is small and mainly concentrates on the range of 1-40 m.

Preparation and Evaluation of Nano-Hydroxyapatite/β-Tricalcium Phosphate/Chitosan Composite Scaffolds for Bone Tissue Engineering

2007 ◽  
Vol 361-363 ◽  
pp. 463-466
Author(s):  
T. Lin ◽  
S.M. Zhang ◽  
J. Li ◽  
L. Zhang ◽  
Y.H. Liu ◽  
...  
Keyword(s):  
Chemical Properties ◽  
Physical And Chemical Properties ◽  
X Ray Diffraction ◽  
Composite Scaffolds ◽  
X Ray ◽  
Viable Cells ◽  
Physical And Chemical ◽  
Chitosan Composite ◽  
Preparation And Evaluation ◽  
And Chemical Properties

The composite scaffolds with nine different ratios of nano-HA and ß-TCP content were fabricated by using lyophilization method. Their microscopy, physical and chemical properties were investigated by using scanning electron microscopy (SEM), X-ray diffraction (XRD), and fourier transformed infrared (FTIR) spectroscopy. MTT test was applied to quantitatively assess the number of viable cells attached and grown on the scaffolds. And the result showed that the amount of cells on the scaffold containing 30% by mass of nano-HA was significantly higher than the other samples.

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