EFFECTS OF QUARTZ PARTICLE SIZE AND SUCROSE ADDITION ON MELTING BEHAVIOR OF A MELTER FEED FOR HIGH-LEVEL GLASS
The behavior of melter feed (a mixture of nuclear waste and glass-forming additives) during waste-glass processing has a significant impact on the rate of the vitrification process. We studied the effects of silica particle size and sucrose addition on the volumetric expansion (foaming) of a high-alumina feed and the rate of dissolution of silica particles in feed samples heated at 5 C/min up to 1200 C. The initial size of quartz particles in feed ranged from 5 to 195 {micro}m. The fraction of the sucrose added ranged from 0 to 0.20 g per g glass. Extensive foaming occurred only in feeds with 5-{micro}m quartz particles; particles {ge}150 {micro}m formed clusters. Particles of 5 {micro}m completely dissolved by 900 C whereas particles {ge}150 {micro}m did not fully dissolve even when the temperature reached 1200 C. Sucrose addition had virtually zero impact on both foaming and the dissolution of silica particles. Over 100 sites in the United States are currently tasked with the storage of nuclear waste. The largest is the Hanford Site located in southeastern Washington State with 177 subterranean tanks containing over fifty-million gallons of nuclear waste from plutonium production from 1944 through 1987. This waste will be vitrified at the Hanford Tank Waste Treatment and Immobilization Plant. In the vitrification process, feed is charged into a melter and converted into glass to be ultimately stored in a permanent repository. The duration of waste-site cleanups by the vitrification process depends on the rate of melting, i.e., on the rate of the feed-to-glass conversion. Foaming associated with the melting process and the rate of dissolution of quartz particles (silica being the major glass-forming additive) are assumed to be important factors that influence the rate of melting. Previous studies on foaming of high-alumina feed demonstrated that varying the makeup of a melter feed has a significant impact on foaming. The volume of feeds that contained 5-{micro}m quartz particles substantially increased because of foaming. The extent of foaming decreased as the particle size of quartz increased. Moreover, samples containing quartz particles 195 {micro}m formed agglomerates at temperatures above 900 C that only slowly dissolved in the melt. This study continues previous work on the feed-melting process, specifically on the effects of the size of silica particles on the formation of nuclear-waste glasses to determine a suitable range of silica particle sizes that causes neither excessive foaming nor undesirable agglomeration. Apart from varying the silica-particle size, carbon was added in the form of sucrose. Sucrose has been used to accelerate the rate of melting. In this study, we have observed its impact on feed foaming and quartz dissolution.
- Research Organization:
- Hanford Site (HNF), Richland, WA (United States)
- Sponsoring Organization:
- USDOE; USDOE Assistant Secretary for Environmental Management (EM)
- DOE Contract Number:
- DE-AC27-08RV14800
- OSTI ID:
- 991931
- Report Number(s):
- ORP-47257-FP Rev 0; TRN: US1007590
- Resource Relation:
- Conference: 51st ANNUAL MEETING INSTITUTE OF NUCLEAR MATERIALS MANAGEMENT (INMM) 07/11/2010 THRU 07/15/2010 BALTIMORE MD
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
ADDITIVES
AGGLOMERATION
CARBON
DISSOLUTION
GLASS
MELTING
MIXTURES
NUCLEAR MATERIALS MANAGEMENT
PARTICLE SIZE
PLUTONIUM
QUARTZ
RADIOACTIVE WASTES
SACCHAROSE
SILICA
STORAGE
TANKS
VITRIFICATION
WASTE PROCESSING
WASTES