Predictive modeling of crystal accumulation in high-level waste glass melters processing radioactive waste

• Published in: Journal of nuclear materials Vol. 495; no. C
• Main Authors: Matyáš, Josef, Gervasio, Vivianaluxa, Sannoh, Sulaiman E., Kruger, Albert A.
• Format: Journal Article
• Language: English
• Published: United States Elsevier 01.11.2017
• Subjects: Crystal accumulation; Empirical model; HLW Glass; Melter; Vitrification
• ISSN: 0022-3115; 1873-4820

The effectiveness of HLW vitrification is limited by precipitation/accumulation of spinel crystals [(Fe, Ni, Mn, Zn)(Fe, Cr)2O4] in the glass discharge riser of Joule-heated ceramic melters during idling. These crystals do not affect glass durability; however, if accumulated in thick layer, they can clog the melter and prevent discharge of molten glass into canisters. To address this problem, an empirical model was developed that can predict thicknesses of accumulated layers as a function of glass composition. This model predicts well the accumulation of single crystals and/or small-scale agglomerates, but, excessive agglomeration observed in high-Ni-Fe glass resulted in an under-prediction of accumulated layers, which gradually worsen over time as an increased number of agglomerates formed. Accumulation rate of ~53.8 ± 3.7 µm/h determined for this glass will result in ~26 mm thick layer in 20 days of melter idling.