A comparison of glass reaction at high and low glass surface/solution volume

Journal Article · Wed Dec 01 04:00:00 EST 1993 · Nuclear Technology; (United States)

OSTI ID:5624737

Ebert, W L; Bates, J K ^[1]

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1. Argonne National Lab., IL (United States)

Static leach tests have been performed at glass surface area/leachant volume (SA/V) ratios of 10, 340, 2,000, and 20,000 m[sup [minus]1] to assess the effects of the SA/V on the mechanism and rate of the glass reaction. Tests were performed using actinide-doped borosilicate waste glasses [Savannah River Laboratory (SRL) 131 and SRL 202] to monitor the distribution of released radionuclides in tests at different SA/V. Solution results show the major effect of the SA/V to be dilution of reaction of products. Differences in the pH and silicic acid concentrations attained in tests at different SA/V then affect the reaction rate. Tests at low SA/V maintain leachate pH values similar to the initial leachant, while tests at higher SA/V result in higher leachate pH values being attained due to ion-exchange reactions. Transuranics released as the glass corrodes may exist in the leachate in concentrations far above their solubility limits by sorbing onto colloids, although the colloids may eventually settle out of solution. Transuranics also sorb onto the steel reaction vessel. The glass reaction progress can be characterized by three stages: (a) an initial stage where the reaction rate depends on the leachant pH, (b) an intermediate stage where the reaction slows toward a minimum rate as the leachate solution approaches saturation,'' and (c) a long-term stage where the reaction rate may be affected by the formation of secondary phases that control the solution chemistry. Tests at different SA/V cannot always be compared directly because the dominant reaction step and the observed reaction stage (initial, intermediate, or long-term) may not be the same.

• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 5624737
• Journal Information: Nuclear Technology; (United States), Journal Name: Nuclear Technology; (United States) Vol. 104:3; ISSN 0029-5450; ISSN NUTYBB
• Country of Publication: United States
• Language: English

Related Subjects

052001* -- Nuclear Fuels-- Waste Processing
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
BOROSILICATE GLASS
DISPERSIONS
DISSOLUTION
GLASS
HIGH-LEVEL RADIOACTIVE WASTES
ISOTOPES
LEACHATES
LEACHING
MATERIALS
MIXTURES
PERFORMANCE TESTING
PH VALUE
RADIOACTIVE MATERIALS
RADIOACTIVE WASTES
RADIOISOTOPES
SEPARATION PROCESSES
SOLUTIONS
SORPTION
SURFACE AREA
SURFACE PROPERTIES
TESTING
VITRIFICATION
WASTE FORMS
WASTES