Investigation of silver behavior in the glass melt and its effect on the IMCC conditions in an industrial-scale furnace
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MRS Advances © 2020 Materials Research Society DOI: 10.1557/adv.2020.146
Investigation of silver behavior in the glass melt and its effect on the IMCC conditions in an industrialscale furnace during vitrification of HLLW simulants 1
Abashkin A. Yu., 1,2Skrigan I. N., 1Ivanov E. Yu., 1Pleshakov A. O., 2Lopukh D.B., 2Vavilov A.V., 2Martynov A. P. 1
Khlopin Radium Institute, 2-i Murinskii av. 28, St. Petersburg, 194021 Russia
2
Saint Petersburg Electrotechnical University «LETI», Prof. Popova st. 5, St. Petersburg, 197376 Russian
ABSTRACT
The large-scale cold crucible induction melter (CCIM) with productivity of 12 kg/h was created for melting borosilicate glass containing 20 mass. % of high-level liquid wastes (HLLW) simulators. Tests were carried out to study the effect on the CCIM operating parameters during sedimentation of metallic silver, at the content of 3.8 mass. % Ag2O in glass. Post-test analyses of the glass shows the sedimentation of silver in the bottom layers of the molten pool. Experiments have confirmed that the presence of noble metals in the form of undissolved sediments in the bottom layers of furnace leads to a changes in the properties of the melt, the aggravation of its drain conditions, an increase in the thermal conductivity of the skull and heat losses during melting.
Introduction One of the promising methods of high - temperature processing of high-level liquid wastes from spent nuclear fuel (SNF) is induction melting in a cold crucible (IMCC) of HLLW together with glass-forming additives at 200-2000 kHz current frequencies. The target product of such processing is borosilicate glass, which has increased resistance to leaching and strong radiation fields. The CCIM method for vitrification of HLLW was first proposed in France in the 60s of last century and various designs of cold crucibles [1, 2] and facilities operating on a two-stage technologies, for example, with preliminary evaporation or calcination of HLLW, have been developed and tested to date. Due to the large diameters of the
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crucibles, the French version of the IMCC is equipped with an additional mechanical stirrer, which significantly complicates the design of the facility as a whole and reduces the reliability of its operation. In Russia, up to now, for more than 35 years, IMCC facilities have been developed with an oscillatory power of the generator feeding the furnace up to 160 kW and with a high current frequency of 1.76 MHz for HLLW solidification using one-stage and two-stage technologies [2-5]. Despite some successes in the use of such facilities in the synthesis of new refractory matrices on a laboratory scale including both model and radioactive materials, this technology has not been brought to realization at radiochemical plants [6]. An important task is to study the in
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