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Title: NUCLEAR WASTE VITRIFICATION EFFICIENCY COLD CAP REACTIONS

Abstract

The cost and schedule of nuclear waste treatment and immobilization are greatly affected by the rate of glass production. Various factors influence the performance of a waste-glass melter. One of the most significant, and also one of the least understood, is the process of batch melting. Studies are being conducted to gain fundamental understanding of the batch reactions, particularly those that influence the rate of melting, and models are being developed to link batch makeup and melter operation to the melting rate. Batch melting takes place within the cold cap, i.e., a batch layer floating on the surface of molten glass. The conversion of batch to glass consists of various chemical reactions, phase transitions, and diffusion-controlled processes. These include water evaporation (slurry feed contains as high as 60% water), gas evolution, the melting of salts, the formation of borate melt, reactions of borate melt with molten salts and with amorphous oxides (Fe{sub 2}O{sub 3} and Al{sub 2}O{sub 3}), the formation of intermediate crystalline phases, the formation of a continuous glass-forming melt, the growth and collapse of primary foam, and the dissolution of residual solids. To this list we also need to add the formation of secondary foam that originates frommore » molten glass but accumulates on the bottom of the cold cap. This study presents relevant data obtained for a high-level-waste melter feed and introduces a one-dimensional (1D) mathematical model of the cold cap as a step toward an advanced three-dimensional (3D) version for a complete model of the waste glass melter. The 1D model describes the batch-to-glass conversion within the cold cap as it progresses in a vertical direction. With constitutive equations and key parameters based on measured data, and simplified boundary conditions on the cold-cap interfaces with the glass melt and the plenum space of the melter, the model provides sensitivity analysis of the response of the cold cap to the batch makeup and melter conditions. The model demonstrates that batch foaming has a decisive influence on the rate of melting. Understanding the dynamics of the foam layer at the bottom of the cold cap and the heat transfer through it appears crucial for a reliable prediction of the rate of melting as a function of the melter-feed makeup and melter operation parameters. Although the study is focused on a batch for waste vitrification, the authors expect that the outcome will also be relevant for commercial glass melting.« less

Authors:
; ;
Publication Date:
Research Org.:
Hanford Site (HNF), Richland, WA (United States)
Sponsoring Org.:
USDOE Office of Environmental Management (EM)
OSTI Identifier:
1025335
Report Number(s):
ORP-49512-FP Rev 0
TRN: US1104834
DOE Contract Number:  
DE-AC27-08RV14800
Resource Type:
Conference
Resource Relation:
Journal Name: JOURNAL OF NON-CRYSTALLINE SOLIDS; Conference: THE 19 UNIVERSITY CONFERENCE ON GLASS SCIENCE -- GLASSES FOR ENERGY RENSSELAER POLYTECHNIC INSTITUTE & THE AMERICAN CERAMIC SOCIETY 08/02/2011 THRU 08/05/2011 TROY NY
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; BORATES; BOUNDARY CONDITIONS; CERAMIC MELTERS; CERAMICS; CHEMICAL REACTIONS; DISSOLUTION; EFFICIENCY; EVAPORATION; GLASS; HEAT TRANSFER; MATHEMATICAL MODELS; MELTING; MOLTEN SALTS; OXIDES; RADIOACTIVE WASTES; SENSITIVITY ANALYSIS; VITRIFICATION; WASTES

Citation Formats

KRUGER AA, HRMA PR, and POKORNY R. NUCLEAR WASTE VITRIFICATION EFFICIENCY COLD CAP REACTIONS. United States: N. p., 2011. Web.
KRUGER AA, HRMA PR, & POKORNY R. NUCLEAR WASTE VITRIFICATION EFFICIENCY COLD CAP REACTIONS. United States.
KRUGER AA, HRMA PR, and POKORNY R. Fri . "NUCLEAR WASTE VITRIFICATION EFFICIENCY COLD CAP REACTIONS". United States. doi:. https://www.osti.gov/servlets/purl/1025335.
@article{osti_1025335,
title = {NUCLEAR WASTE VITRIFICATION EFFICIENCY COLD CAP REACTIONS},
author = {KRUGER AA and HRMA PR and POKORNY R},
abstractNote = {The cost and schedule of nuclear waste treatment and immobilization are greatly affected by the rate of glass production. Various factors influence the performance of a waste-glass melter. One of the most significant, and also one of the least understood, is the process of batch melting. Studies are being conducted to gain fundamental understanding of the batch reactions, particularly those that influence the rate of melting, and models are being developed to link batch makeup and melter operation to the melting rate. Batch melting takes place within the cold cap, i.e., a batch layer floating on the surface of molten glass. The conversion of batch to glass consists of various chemical reactions, phase transitions, and diffusion-controlled processes. These include water evaporation (slurry feed contains as high as 60% water), gas evolution, the melting of salts, the formation of borate melt, reactions of borate melt with molten salts and with amorphous oxides (Fe{sub 2}O{sub 3} and Al{sub 2}O{sub 3}), the formation of intermediate crystalline phases, the formation of a continuous glass-forming melt, the growth and collapse of primary foam, and the dissolution of residual solids. To this list we also need to add the formation of secondary foam that originates from molten glass but accumulates on the bottom of the cold cap. This study presents relevant data obtained for a high-level-waste melter feed and introduces a one-dimensional (1D) mathematical model of the cold cap as a step toward an advanced three-dimensional (3D) version for a complete model of the waste glass melter. The 1D model describes the batch-to-glass conversion within the cold cap as it progresses in a vertical direction. With constitutive equations and key parameters based on measured data, and simplified boundary conditions on the cold-cap interfaces with the glass melt and the plenum space of the melter, the model provides sensitivity analysis of the response of the cold cap to the batch makeup and melter conditions. The model demonstrates that batch foaming has a decisive influence on the rate of melting. Understanding the dynamics of the foam layer at the bottom of the cold cap and the heat transfer through it appears crucial for a reliable prediction of the rate of melting as a function of the melter-feed makeup and melter operation parameters. Although the study is focused on a batch for waste vitrification, the authors expect that the outcome will also be relevant for commercial glass melting.},
doi = {},
journal = {JOURNAL OF NON-CRYSTALLINE SOLIDS},
number = ,
volume = ,
place = {United States},
year = {Fri Jul 29 00:00:00 EDT 2011},
month = {Fri Jul 29 00:00:00 EDT 2011}
}

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