- Richard Pokorny
- Jaroslav Klouzek
- Miroslava Hujova
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Technická 5
166 28 Prague 6 – Dejvice
IČO: 60461373 / VAT: CZ60461373
Czech Post certified digital mail code: sp4j9ch
Copyright: UCT Prague 2015
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Laboratory of Inorganic Materials is joint working place of the University of Chemistry and Technology Prague and the Institute of rock structure and mechanics ASCR, v.v.i. Laboratory activity evenly covers the area of education and both basic and applied research.
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Melting space for the vitrification of radioactive materials |
For students
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Bubble in glass containig Na2SO4 condensate |
Laboratory members are involved in the education within bachelor and master study programs Chemistry and Materials. Doctoral students of the study program Chemistry and Technology of Inorganic Materials work closely with us when assisting solved research projects, completing required coursework and writing and defending a dissertation about their research project. |
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The result of the mathematical model of the flow in the melting chamber - sectional view showing the formation of spiral flow, which allows to increase the efficiency of the melting process. |
Image analysis - measurement of the size of a bubble in the melt. |
Laboratory of Inorganic Materials was created from the original Laboratory for chemistry and technology of silicates and ICT Prague and ASCR founded in 1961. In 2012, the Laboratory was transformed into a Joint workplace of the University of Chemistry and Technology Prague UCT Prague) and the Institute of Rock Structure and Mechanics ASCR, v.v.i. The Laboratory cooperates with materials-oriented UCT Prague departments, especially the Department of glass and ceramics. In addition to the labs in UCT Prague (Building A, Room A04), we also work at the Institute of Rock Structure and Mechanics ASCR v.v.i., V Holešovičkách 41, 180 00 Prague 8.
Temperature distribution on the top melt level in a glass melting space
Postgraduate study programme: Chemistry and Technology of Materials
Field of study: Chemistry and technology of inorganic materials
Themes of the postgraduate studies
Supervisor: Prof. Ing. Lubomír Němec, DrSc.
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Supervisor: Doc. Ing. Jaroslav Kloužek, CSc.
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Supervisor: Doc. Ing. Jaroslav Kloužek, CSc. |
Supervisor: Prof. Ing. Lubomír Němec, DrSc.
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Research areas |
Glass melting processes and their modelling |
New glass melting concepts |
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Mathematical modeling is traditional tool for the analysis of glass melting process. CFD methods calculate velocity and temperature fiels ... |
New relative value – space utilization – quantitatively assesses melting processes in continuous melting space. The current industrial furnaces... | ||
Development of new types of glasses |
Materials for photonics and optoelectronics |
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The composition of the proposed glass is optimized in terms of the required properties. Colors affected by the redox state of the glass can be predicted ... |
The industrial development is coming with a requirement of new materials. In optic and optoelectronic ... |
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Research of processes for vitrification of nuclear waste |
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Solving the problem of immobilizing a large amount of nuclear waste coming from the production of plutonium is the actual question ... |
Experimental techniques
UCT Prague |
IRSM ASCR, v.v.i. |
University of Chemistry and Technology Prague Laboratory of Inorganic Materials Technická 5 166 28 Prague 6 Czech Republic
Tel. +420 22044 5192 (l. 4318, 5195) E-mail: Jaroslav.Klouzek@vscht.cz |
Institute of Rock Structure and Mechanics ASCR, v.v.i. Laboratory of Inorganic Materials V Holešovičkách 41 180 00 Prague 8 Czech Republic
Tel. +420 266009 421 (l. 423) |
Public transportation: |
Public transportation: Metro Line "C" to Holešovice station, exit to Kobylisy, Prosek, then by bus 102, 210 to Vychovatelna station. Metro Line "B" to Palmovka station, exit to Divadlo pod Palmovkou, then by tram 10, 24, 25 to Vychovatelna station. |
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As part of an international collaboration, we are working in our laboratory to develop a model for the melting of the glass batch/feed in the melter. Using our mathematical model, we will be able to predict the glass production rate and help to optimize the entire melting process.
Nuclear Waste vitrification
In Hanford, in the northwest of the US in Washington, more than 200,000 m3 of radioactive waste is stored in underground tanks, a result of the plutonium production during the II. World war and Cold war. This waste is stored in 177 aging underground tanks, which have problems with leakage that leads to the contamination of underground and threatens the nearby Columbia River, the second largest river on the Pacific coast of North America.
In order to process and stabilize the radioactive waste, a Waste Treatment Plant (WTP) is now being built at Hanford. The radioactive waste will be mixed with glass-forming and glass-modifying chemicals and melted at 1150 °C in an electric furnace. The resulting glass will be poured into stainless-steel canisters, where the glass will cool and solidify. In the form of glass, the radioactive waste will be stable and safe for a long-term storage in an underground repository.
Although the vitrification of radioactive waste is a proven technology that has been successfully employed for decades, it has never been used on such a large scale and for such complex nuclear waste, as is stored at Hanford. The vitrification plant is thus a huge engineering challenge and one of the world's most complex remediation projects. For example, only the waste pre-treatment and separation plant (dividing the waste into low-activity and high-level fractions) has a ground plan of 165 x 65 meters, and is 12 floors high.
Our group has a long-history working on various aspects of waste glass melting at Hanford. In 2018, another two-year grant from Department of Energy (DoE USA) was awarded to our laboratory to work on the nuclear waste vitrification project at Hanford.
Selected publications
- Lee S., Hrma P., Pokorny R., Klouzek J., VanderVeer B., Rodriguez C., Chun J., Schweiger M., Kruger A. (2017). Effects of alumina sources (gibbsite, boehmite, and corundum) on melting behavior of high-level radioactive waste melter feed. MRS ADVANCES. 2, 11, 603-608.
doi: 10.1557/adv.2016.644 - Lee S., Hrma P., Pokorny R., Klouzek J., VanderVeer B.J., Dixon D.., Luksic S.A., Rodriguez C.P., Chun J., Schweiger M.J., Kruger A.A. (2017). Effect of melter feed foaming on heat flux to the cold cap. Journal of Nuclear Materials. 496, 54-65. doi: 10.1016/j.jnucmat.2017.09.016
- Lee S., Hrma P., Kloužek J., Pokorný R., Hujová M., Dixon D.R., Schweiger M.J., Kruger A.A. (2017): Balance of oxygen throughout the conversion of a high-level waste melter feed to glass. Ceramics International. 43, 13113-13118. doi: 10.1016/j.ceramint.2017.07.002
- Hujova M., Pokorny R., Klouzek J., Dixon D.R., Cutforth A., Seungmin Lee, McCarthy B.P., Michael J. Schweiger M.J., Kruger A.A., Hrma P. (2017): Determination of Heat Conductivity of Waste Glass Feed and its Applicability for Modeling the Batch-to-Glass Conversion. Journal of the American Ceramic Society. 100, 5096-5106. doi: 10.1111/jace.15052
- Lee, S., VanderVeer, B. J., Hrma, P., Hilliard, Z. J., Heilman-Moore, J. S., Bonham, C. C., Pokorny, R., Dixon, D. R., Schweiger, M. J. and Kruger, A. A. (2017). Effects of Heating Rate, Quartz Particle Size, Viscosity, and Form of Glass Additives on High-Level Waste Melter Feed Volume Expansion. Jornal of the American Ceramic Society. doi:10.1111/jace.1462
- Pokorný R., Hilliard Z., Dixon D., Schweiger M., Guillen D., Kruger A., Hrma P. (2015). One-Dimensional Cold Cap Model for Melters with Bubblers. Journal of the American Ceramic Society, 98, 3112-3118.
- Richard Pokorny
- Jaroslav Klouzek
- Miroslava Hujova
E-mail: | richard.pokorny at vscht.cz |
Phone: |
+420 220 445 191 +420 220 444 318 |
Room: | A 04 |
- Preparation of glasses under defined conditions
- Visual observation of glass melting processes
- Solubilities of gases in melts
- Diffusion coefficients of gases in melts
- Image analysis
- Evolved gas analysis
- Oxygen partial pressure in melts
Determination of the solubility of gases in the glass melt consists of two steps. In the first step, the melt flows are saturated using the pure gas. After reaching equilibrium, the melt is rapidly cooled to room temperature. The concentration of dissolved gas is then determined by the gas chromatographic method described below. The principle of the determination of gases dissolved in the glass melt is the continuous extraction of the dissolved gas from the melt by the flow of inert gas and subsequent chromatographic analysis of the released gases. The analyzed glass sample in the form of a 5 x 5 x 10 mm rectangular block is placed in a quartz glass tube inserted in a laboratory tube furnace heated to 1500 ° C. At the bottom of the test tube, helium flows through quartz capillary. Released gases are captured in a concentration loop immersed in liquid nitrogen. After completion of the extraction (60 minutes), the loop is quickly heated by immersion in hot oil and transferred to the carrier gas circuit of the chromatograph. The determination method allows the simultaneous determination of carbon dioxide, oxygen, nitrogen, and sulfur dioxide. Other dissolved gases, such as water vapor or argon, cannot be determined in this arrangement. |
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Figure: Measuring instruments for gas analysis in melts |
Figure: Schematics of saturation of melt by gas |
Diagram of apparatus for determining gases in the melt
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The principle of the method is illustrated in Figure 1. The gas whose diffusion coefficient is measured is inserted through a platinum tube into a cylindrical quartz glass container just above the surface of the molten glass inside the optical cuvette located in the laboratory furnace. After filling with the gas, the container is pushed below the melt level. Gas absorption is measured by the rise of the melt inside the container, which is captured by the video camera through a special hole in the side of the laboratory furnace, see Figure 2. An image analyzer, measuring the distance between the gas-melt interface and the upper end of the container, is used to evaluate the measurement. |
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Figure: Schematics of the experimental setup: 1 - glass melt cuvette 2 - cylindrical quartz measuring vessel 3 - measuring cup holder 4 - moving gas-melt interface 5 - melt level inside the cuvette | Figure: The movement of the gas-melt interface when measuring the water vapor diffusion coefficient of sodium-calcium-silicate glass, temperature 1200 ° C. a) 15000 s, b) 20000 s, c) 40000 s, d) 60000 s |
We use LUCIA software (Laboratory Universal Computing Image Analysis) developed by Laboratory Imaging (currently part of NIS-elements). The image analyzer allows to directly capture video signals from your video camera. When processing images under a microscope or from high-temperature tracking in melt processes, we usually use length and number measurement and particle size distribution. |
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Figure: Measurement of the gas-melt interface displacement inside the quartz container during the determination of the diffusion coefficient of the gas in the melt. | |
Figure: Original image | Figure: Contrast adjustment |
Figure: Measurement of the field inside the measuring frame |
Figure: Results of analysis |
During the evolved gas analysis, the analyzed sample is placed in a quartz glass test tube and inserted in a tubular laboratory furnace. At the bottom of the test tube, a quartz glass capillary is used to insert the helium (carrier gas) flow. The furnace temperature increases at a defined linear rate. Helium carries the released gases into the gas chromatograph. The result of the analysis is the temperature dependence of the amount of released gases. The sensitivity of the used setup allows analyzing also a trace amount of gases evolving during final stages of the batch to glass conversion and during fining. |
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Figure: Measuring equipment | Figure: Results of analysis |
The Redox state expresses the relationship between the oxidation forms of transition metal present in the melt, mainly iron, chromium and other elements. The redox state controls the resulting glass color, the value of the effective thermal conductivity, and the bubble removal process (refining process). The redox state of the melt is also important in calculations of the distribution of oxidation-reducing components in glass melting furnaces or in bubble nucleation. The commercially available method of measuring the redox state of glass is the Rapidox system. The method is based on electrochemical measurement of the equilibrium voltage between the reference and the measuring electrode. The measuring electrode is a Pt or Ir wire. The reference electrode is located in a Ni / NiO mixture which guarantees a defined partial pressure of oxygen. From the measured value of electromotive voltage E (V), the partial pressure of oxygen is calculated using the Nernst equation. |
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Figure: RAPIDOX system | Figure: Measuring probe |