Alternative reductants for foam control during vitrification of high-iron High Level Waste (HLW) feeds

RIGBY, Jessica, DIXON, Derek, KLOUZEK, Jaroslav, POKORNY, Richard, THOMPSON, Paul, SCRIMSHIRE, Alex, KRUGER, Albert, BELL, Anthony and BINGHAM, Paul (2023). Alternative reductants for foam control during vitrification of high-iron High Level Waste (HLW) feeds. Journal of Non-Crystalline Solids, 608: 122240.

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Abstract

Foaming during vitrification of radioactive waste in Joule-Heated Ceramic Melters (JHCM) is exacerbated by trapping of evolving gases, such as CO2, NOx and O2, beneath a viscous reaction layer. Foaming restricts heat transfer during melting. Sucrose is employed as the baseline additive at the Hanford site in Washington State, USA to reduce foaming. Alternative carbon-based reductant additives were explored in simulated, inactive Hanford high-iron HLW-NG-Fe2 feeds, for both their effect on foaming and to give insight to the behaviour of multivalent species in glass melts under different redox conditions. Graphite, coke (93% C), formic acid and HEDTA additives were compared with sucrose, and a feed with no additive. Graphite and coke additions proved most effective in reducing the maximum foam volume by 51 ± 3% and 54 ± 2%, respectively, compared with 24 ± 5% for sucrose. Lower foaming could result in more efficient vitrification in JHCMs. Reductants also affected redox ratios in the multivalent species present in the feed. The order of reduction, Mn3+/Mn2+ > Cr6+/Cr3+ > Ce3+/Ce4+ > Fe3+/Fe2+ was as predicted on the basis of their redox potentials. There is less reduction overall, particularly in the Fe3+ → Fe2+, than predicted by the calculations, attributed to the oxygenated atmosphere of the experiments.

Item Type:	Article
Uncontrolled Keywords:	0204 Condensed Matter Physics; 0912 Materials Engineering; Applied Physics; 3403 Macromolecular and materials chemistry; 4016 Materials engineering; 5104 Condensed matter physics
Identification Number:	https://doi.org/10.1016/j.jnoncrysol.2023.122240
SWORD Depositor:	Symplectic Elements
Depositing User:	Symplectic Elements
Date Deposited:	27 Feb 2023 16:45
Last Modified:	10 Mar 2023 12:47
URI:	https://shura.shu.ac.uk/id/eprint/31558

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