Cold-cap formation from a slurry feed during nuclear waste vitrification. Issue 5 (1st April 2019)

• Record Type: Journal Article
• Authors: Hujová, Miroslava; Klouzek, Jaroslav; Cutforth, Derek A.; Lee, SeungMin; Miller, Micah D.; McCarthy, Benjamin; Hrma, Pavel R.; Kruger, Albert A.; Pokorný, Richard
• Is Part Of: Ceramics international. Volume 45:Issue 5(2019)
• Page Start: 6405
• Page End: 6412
• Publication Date: 2019-04-01
• Subjects: X-ray methods -- Cold-cap -- Chemical properties -- Thermal conductivity -- Nuclear applications -- Glass; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2018.12.127
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: The time-temperature history of waste slurry feed during melting strongly affects various kinetic processes, such as reaction or dissolution rates, and, consequently, the melting rate. To analyze the time-temperature history of the feed in a cold-cap during nuclear waste vitrification, this work focuses on understanding how the main cold-cap body forms, how the aqueous feed slurry interacts with the cold-cap, and estimating the cold-cap heat conductivity. To simulate the conditions during cold-cap formation, samples were prepared by rapid water evaporation from slurry feed. After water evaporated from the sample, a fresh slurry with tracer was poured onto the dry sample. X-ray fluorescence was then used to investigate the degree of penetration and/or mixing between the incoming slurry and the original sample. We show that the slurry does not interact or mix with the previously dry cold-cap crust, but that water-soluble components concentrate at the bottom of the boiling pools, where most of the water evaporates. Further, using the rate of water evaporation, the heat conductivity of the cold-cap was calculated from the measured temperature profile. The resulting conductivity is significantly higher than the values obtained in previous studies. We discuss the implications of the results for the cold-cap formation in the melter and for the development of the cold-cap mathematical model.