Development and Characteristics of a New Porous Glass Crystalline Matrix (Gubka) for Stabilizing Radioactive and Hazardo
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Development and Characteristics of a New Porous Glass Crystalline Matrix (Gubka) for Stabilizing Radioactive and Hazardous Solutions A. G. Anshits1, A. S. Aloy2, A. A. Tretyakov3, D. A. Knecht4, T. J. Tranter4, O. M. Sharonova1, T. A. Vereshchagina1, I. D. Zykova1, M. V. Burdin3, N.V. Sapozhnikova2, A. V. Strelnikov2 and J. Macheret4 1 Institute Chemistry and Chemical Technology, Siberian Branch of the Russian Academy of Sciences (ICCT SB RAS), 42 K. Marx St., Krasnoyarsk 660049, Russia; 2 V. G. Khlopin Radium Institute (KRI), 28 2-nd Murinskiy Ave., St. Petersburg, 194021, Russia; 3 Federal State Unitary Enterprise “Mining and Chemical Combine” (FSUE MCC), 53 Lenin St., Zheleznogorsk, Krasnoyarsk Region, 662990, Russia; 4 Idaho National Engineering and Environmental Laboratory, P. O. Box 1625, Idaho Falls, ID 83415 ABSTRACT This paper describes the results of a joint research program of Russian institutes at St. Petersburg, Krasnoyarsk and Zheleznogorsk and the Idaho National Engineering and Environmental Laboratory to develop a new material for stabilizing radioactive solutions and other uses, such as high-temperature catalysis. An open-cell glass crystalline porous material, Gubka, or “sponge” in Russian, having an open-cell porosity of up to 90 %, was produced from hollow glass crystalline microspheres (cenospheres) formed in fly ash from coal combustion. The cenospheres were separated into fractions based on grain size, density, magnetic properties, and whether or not they were perforated. Selected fractions were molded and agglomerated by sintering with or without a binder at high temperatures. Depending on the cenosphere fractions selected, sintering conditions and additional treatments, Gubka was formed with an open-cell porosity ranging from 40-90 %. The porous material has a bulk density of 0.3-0.6 g/cm3, and two types of porous openings: 0.1-30 micrometer flow-through pores in the cenosphere walls and 20-100 micrometer interglobular pores between the cenospheres. Examples of Gubka application described in this paper include stabilization of different surrogate radioactive waste solutions containing 0.0001 to 0.7 M nitric/hydrochloric acid and 0 to 1.2 M sodium nitrate. Waste solid loadings of 46-55 wt.% nitrate salts, or 26-37 wt.% oxides after calcination, were achieved in those tests. INTRODUCTION Different types of open-cell porous inorganic materials studied previously as a primary matrix for radioactive waste immobilization include porous glasses [1, 2], silica gel [3, 4] and foam corundum [5-8]. Khlopin Radium Institute has also studied porous fireclay (chamotte) and diatomite for this purpose. However, after loading with radioactive waste solution, these materials generally require drying at high temperatures close to the boiling point of the solution, and this can increase processing complexity. In addition, some of these materials have nonuniform porous structures and a wide range of pore sizes, which can affect the waste form loading and stability.
Open-cell porous materials formed from granul
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