R&D on Surrogate Kernel Fabrication in Support of Reaktor Daya Eksperimental (RDE) Project

Abstract R&D program on HTGR fuel to support the RDE project has been outlined and is aimed to develop national capabilities on nuclear fuel technology. The external sol-gel technology has been adopted for the fabrication of kernels. Laboratory scale work has been ongoing at the Center for Nuclear Fuel Technology (PTBBN) BATAN to study various parameters involved in the process of kernel fabrication including tuning of parameters related to droplet formation (feed flow rate, vibrator frequency, NH3 gas flow rate), optimizing chemical formulation in broth preparation, various treatments in aging, washing, drying process, and thermal treatment for densification of kernels. In this early stage, zirconium precursors were used to manufacture surrogate kernels of ytrria-stabilized zirconia. The steps for kernel fabrication include chemical formulation of broth and droplet casting, aging-washing-drying of gel microspheres, calcination and sintering, and characterization of sintered kernels (surface morphology, density, diameter/sphericity, solid phase). Stable cast of droplets from 1 mm nozzle diameter was optimized by adjusting feed flowrate at 30 ml/min, viscosity at 45-60 cP, and vibrating frequency at 100 Hz. Presolidification of gel skin was optimized at a working NH3 flow rate of 3.5 - 4 L/min. Addition of urea with mole ratio urea/metal 2.5/1.0 gave the most preferable results based on SEM examination for crack and morphological structure. Control the opaqueness of the sol can be done by portioning addition of urea, where a portion of urea was added at decomposing temperature around 85°C, while another portion was added at a lower temperature. Addition of urea has a desirable effect on crack reduction during heat treatment of gel microspheres. Increase in metal concentration results in an increase in kernel diameter when other sol-to-gel conversion parameters were kept unvaried. Phase determination by X-Ray Diffractometer indicates that solid phase for ceria-stabilized zirconia prepared with precursor composition of 16% yttrium in zirconium-yttrium sol results in yttria-stabilized zirconia 8YSZ with cubic phase.

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Effect of Deposition Conditions on Phase Content and Mechanical Properties of Yttria-Stabilized Zirconia Thin Films Deposited by Sol-Gel/Dip-Coating

Journal of Nanomaterials ◽

10.1155/2021/4449890 ◽

2021 ◽

Vol 2021 ◽

pp. 1-9

Author(s):

Francisco J. Cano ◽

Orlando Castilleja-Escobedo ◽

L. J. Espinoza-Pérez ◽

Cecilia Reynosa-Martínez ◽

Eddie Lopez-Honorato

Keyword(s):

Heat Treatment ◽

Wear Rate ◽

Adhesion Strength ◽

Surface Defects ◽

Sol Gel ◽

Dip Coating ◽

Yttria Stabilized Zirconia ◽

Cubic Phase ◽

Phase Content ◽

Stabilized Zirconia

The effect of yttria concentration (0-33.4 mol%), extraction rates (0.17, 0.33, 0.50, and 0.67 mm s-1), and the number of layers (up to four) on the phase content, surface defects, thickness, hardness, adhesion strength, and wear rate of yttria-stabilized zirconia coatings produced by sol-gel/dip-coating were studied for its use on thermolabile substrates. At 700°C, a metastable tetragonal phase ( t ″ ) was obtained even with 33.4 mol% yttria when heat treated for 24 hours; however, a fully cubic structure was attained by extending the heat treatment up to 48 hours as confirmed by Raman spectroscopy. Furthermore, it was necessary to use withdrawal speeds of at least 0.67 mm s-1 to produce defect-free coatings. Although the coatings were produced at low temperature, they showed 41% lower wear rate than steel and an adhesion strength of 30 MPa. Our work stresses the importance of the heat treatment history on the stabilization of the cubic phase in sol-gel YSZ coatings.

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Identification of tetragonal and cubic structures of zirconia using synchrotron x-radiation source

Journal of Materials Research ◽

10.1557/jmr.1991.1287 ◽

1991 ◽

Vol 6 (6) ◽

pp. 1287-1292 ◽

Cited By ~ 110

Author(s):

Ram Srinivasan ◽

Robert J. De Angelis ◽

Gene Ice ◽

Burtron H. Davis

Keyword(s):

Particle Size ◽

Radiation Source ◽

Sol Gel ◽

Yttria Stabilized Zirconia ◽

Tetragonal Structure ◽

Cubic Phase ◽

X Ray Diffraction ◽

Stabilized Zirconia ◽

Synchrotron Source ◽

Three Samples

X-ray diffraction from a synchrotron source was employed in an attempt to identify the crystal structures in zirconia ceramics produced by the sol-gel method. The particles of chemically precipitated zirconia, after calcination below 600 °C, are very fine, and have a diffracting particle size in the range of 7–15 nm. As the tetragonal and cubic structures of zirconia have similar lattice parameters, it is difficult to distinguish between the two. The tetragonal structure can be identified only by the characteristic splittings of the Bragg profiles from the “c” index planes. However, these split Bragg peaks from the tetragonal phase in zirconia overlap with one another due to particle size broadening. In order to distinguish between the tetragonal and cubic structures of zirconia, three samples were studied using synchrotron radiation source. The results indicated that a sample containing 13 mol% yttria-stabilized zirconia possessed the cubic structure with a0 = 0.51420 ± 0.00012 nm. A sample containing 6.5 mol% yttria stabilized zirconia was found to consist of a cubic phase with a0 = 0.51430 ± 0.00008 nm. Finally, a sample which was precipitated from a pH 13.5 solution was observed to have the tetragonal structure with a0 = 0.51441 ± 0.00085 nm and c0 = 0.51902 ± 0.00086.

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Pressure Drops in the Pneumatic Conveyance of Solids

Journal of Applied Mechanics ◽

10.1115/1.4010538 ◽

1952 ◽

Vol 19 (4) ◽

pp. 425-431

Author(s):

Oscar Pinkus

Keyword(s):

Flow Rate ◽

Pressure Loss ◽

Gas Flow ◽

Solid Phase ◽

Gas Velocity ◽

Air Velocity ◽

Pressure Drops ◽

Pneumatic Conveyance ◽

The Relationship ◽

Group D

Abstract With the object of studying the characteristics of the horizontal flow of a mixture of solids and air a theoretical analysis of the flow pattern was attempted. Experiments were performed whose object was to determine the relationship between pressure loss, solids flow rate, and air velocity, and to obtain values for the frictional constants involved in the analysis. A justification for the developed equations was sought. It was found that the presence of the solid phase causes an appreciable pressure loss which is a linear function of both solid and gas flow rate. This justified the theoretical equations which predicted such a relationship. Experiments with two sizes of the same sand showed a higher pressure drop for the larger particles, other conditions being equal. These experiments, however, question the validity of applying the Fanning equation to a solid phase. The equation holds for a given solid but does not take into account variations in its size. The introduction of the dimensionless group d/D is proposed. On the basis of this investigation, it is concluded that the drag coefficient C is a function of the Reynolds number. The ratio of solids velocity to gas velocity is 0.5–0.6 for the small and 0.3 for the large sand. Following results of this work it would seem desirable to operate pneumatic systems at low gas velocities and high solid rates. Recommendations for further investigations are made.

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Characterization of Calcia Stabilized Zirconia as a solid Electrolyte Made through a sol gel Method in Solid Oxide Fuel Cell

International Journal of Engineering and Advanced Technology - Regular Issue ◽

10.35940/ijeat.a1628.109119 ◽

2019 ◽

Vol 9 (1) ◽

pp. 3056-3060

Keyword(s):

Fuel Cell ◽

Solid Oxide Fuel Cell ◽

Solid Electrolyte ◽

Sol Gel ◽

Solid Oxide ◽

Cubic Phase ◽

Oxide Fuel ◽

Stabilized Zirconia ◽

Gel Method ◽

Sol Gel Method

Solid Oxide Fuel Cell (SOFC) is a solid-state energy conversion device which produces electricity through the conversion of chemical energy directly to electrical energy. The research was carried out to characterize Calcia Stabilized Zirconia (CSZ) that was made using sol gel method. In this study, the production of CSZ pellets consisted of three steps. First step was the extraction of ZOC (ZrOCl28H2O) and second step was the production of Zr(OH)4 and the last step was dissolution of ZrOH4 into HCl and then adding CaO to get CSZ powder. The CSZ powder was then pressed to form pellets, followed by sintering at 1200 oC for 3 hours. The characterization was conducted using X ray diffraction to analyze the presence of impurities as well as the formation of cubic phase and scanning electron microscope was used to observe the pores in the microstructure. From the XRD data and SEM analysis, it can be concluded that the Calcia Stabilized Zirconia as a solid electrolyte in SOFC using sol gel method gave promising results.

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SCIENTIFIC AND ENGINEERING PRINCIPLES OF EFFICIENT FUEL USE AND ENVIRONMENTALLY FRIENDLY GAS COMBUSTION IN STOVE PLATES. PART 1. MODERN STATE-OF-THE-ART AND DIRECTIONS FOR IMPROVEMENT THE GAS BURNING IN DOMESTIC GAS COOKERS

Energy Technologies & Resource Saving ◽

10.33070/etars.3.2017.01 ◽

2017 ◽

pp. 3-18 ◽

Cited By ~ 1

Author(s):

B.S. Soroka ◽

V.V. Horupa

Keyword(s):

Natural Gas ◽

Flow Rate ◽

Gas Flow ◽

Renewable Energy Sources ◽

Combustion Process ◽

Orifice Diameter ◽

Firing Process ◽

Gas Flow Rate ◽

Gas Combustion ◽

Gas Stoves

Natural gas NG consumption in industry and energy of Ukraine, in recent years falls down as a result of the crisis in the country’s economy, to a certain extent due to the introduction of renewable energy sources along with alternative technologies, while in the utility sector the consumption of fuel gas flow rate enhancing because of an increase the number of consumers. The natural gas is mostly using by domestic purpose for heating of premises and for cooking. These items of the gas utilization in Ukraine are already exceeding the NG consumption in industry. Cooking is proceeding directly in the living quarters, those usually do not meet the requirements of the Ukrainian norms DBN for the ventilation procedures. NG use in household gas stoves is of great importance from the standpoint of controlling the emissions of harmful components of combustion products along with maintenance the satisfactory energy efficiency characteristics of NG using. The main environment pollutants when burning the natural gas in gas stoves are including the nitrogen oxides NOx (to a greater extent — highly toxic NO2 component), carbon oxide CO, formaldehyde CH2O as well as hydrocarbons (unburned UHC and polyaromatic PAH). An overview of environmental documents to control CO and NOx emissions in comparison with the proper norms by USA, EU, Russian Federation, Australia and China, has been completed. The modern designs of the burners for gas stoves are considered along with defining the main characteristics: heat power, the natural gas flow rate, diameter of gas orifice, diameter and spacing the firing openings and other parameters. The modern physical and chemical principles of gas combustion by means of atmospheric ejection burners of gas cookers have been analyzed from the standpoints of combustion process stabilization and of ensuring the stability of flares. Among the factors of the firing process destabilization within the framework of analysis above mentioned, the following forms of unstable combustion/flame unstabilities have been considered: flashback, blow out or flame lifting, and the appearance of flame yellow tips. Bibl. 37, Fig. 11, Tab. 7.

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