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Title: Evaluation of Solution Composition Aluminoborosilicate Waste Glass Dissolution at 40°C

Abstract

Single-pass flow-through experiments were conducted with aluminoborosilicate waste glasses to evaluate how changes in solution composition affect the dissolution rate (r) at 40°C and pH(23°C) = 9.0. The three prototypic low-activity waste (LAW) glasses; LAWE-1A, -95A, and -290A, used in these experiments span a wide range covering the expected processing composition of candidate immobilized low-activity waste (ILAW) glasses. Results suggest incongruent release of Al, B, Na, and Si at low flow-rate (q) to sample surface area (S) [log10 (q/S) < -8.9 (m/s)] whereas congruent release was observed at high q/S [log10 (q/S) > -7.9 (m/s)]. Forward dissolution rates, based on boron release, are the same irrespective of glass composition, evident by the dissolution rates being within the experimental error of one another [r1A = 0.0301 ±0.0153 g/(m2 d), r95A = 0.0248 ±0.0125 g/(m2 d), and r290A = 0.0389 ±0.0197 g/(m2 d)]. Finally these results support the use of a chemical affinity based rate law to describe glass dissolution as a function of solution composition.

Authors:
; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
910004
Report Number(s):
PNNL-SA-52923
14592; 830403000; TRN: US0704032
DOE Contract Number:
AC05-76RL01830
Resource Type:
Conference
Resource Relation:
Conference: Preprints of extended abstracts presented at the ACS National Meeting, American Chemical Society, Division of Environmental Chemistry, 2007, 47(1):125-134
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; 36 MATERIALS SCIENCE; BOROSILICATE GLASS; ALUMINIUM OXIDES; WASTE FORMS; DISSOLUTION; FLOW RATE; SURFACE AREA; CHEMICAL COMPOSITION; LOW-LEVEL RADIOACTIVE WASTES; CHEMICAL REACTION KINETICS; dissolution kinetics; low-activity waste glass; LAW; Environmental Molecular Sciences Laboratory

Citation Formats

Richards, Emily L., Davis, Aaron M., and Pierce, Eric M.. Evaluation of Solution Composition Aluminoborosilicate Waste Glass Dissolution at 40°C. United States: N. p., 2007. Web.
Richards, Emily L., Davis, Aaron M., & Pierce, Eric M.. Evaluation of Solution Composition Aluminoborosilicate Waste Glass Dissolution at 40°C. United States.
Richards, Emily L., Davis, Aaron M., and Pierce, Eric M.. Thu . "Evaluation of Solution Composition Aluminoborosilicate Waste Glass Dissolution at 40°C". United States. doi:.
@article{osti_910004,
title = {Evaluation of Solution Composition Aluminoborosilicate Waste Glass Dissolution at 40°C},
author = {Richards, Emily L. and Davis, Aaron M. and Pierce, Eric M.},
abstractNote = {Single-pass flow-through experiments were conducted with aluminoborosilicate waste glasses to evaluate how changes in solution composition affect the dissolution rate (r) at 40°C and pH(23°C) = 9.0. The three prototypic low-activity waste (LAW) glasses; LAWE-1A, -95A, and -290A, used in these experiments span a wide range covering the expected processing composition of candidate immobilized low-activity waste (ILAW) glasses. Results suggest incongruent release of Al, B, Na, and Si at low flow-rate (q) to sample surface area (S) [log10 (q/S) < -8.9 (m/s)] whereas congruent release was observed at high q/S [log10 (q/S) > -7.9 (m/s)]. Forward dissolution rates, based on boron release, are the same irrespective of glass composition, evident by the dissolution rates being within the experimental error of one another [r1A = 0.0301 ±0.0153 g/(m2 d), r95A = 0.0248 ±0.0125 g/(m2 d), and r290A = 0.0389 ±0.0197 g/(m2 d)]. Finally these results support the use of a chemical affinity based rate law to describe glass dissolution as a function of solution composition.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Mar 01 00:00:00 EST 2007},
month = {Thu Mar 01 00:00:00 EST 2007}
}

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  • Single-pass flow-through (SPFT) experiments were conducted with aluminoborosilicate waste glasses to evaluate how changes in solution composition affect the dissolution rate (r) at 40°C and pH(23°C) = 9.0. The three prototypic low-activity waste (LAW) glasses; LAWE-1A, -95A, and -290A, used in these experiments span a wide range covering the expected processing composition of candidate immobilized low-activity waste (ILAW) glasses. Results suggest incongruent release of Al, B, Na, and Si at low flow-rate (q) to sample surface area (S) [log10 (q/S) < -8.9 (m s-1)] whereas congruent release was observed at high q/S [log10 (q/S) > -7.9 (m s-1)]. Dissolution ratesmore » increase from log10 (q/S) ≈ -9.3 to -8.0 (m s-1) and then become constant at log10 (q/S) > -7.9 (m s-1). Forward (maximum) dissolution rates, based on B release, are the same irrespective of glass composition, evident by the dissolution rates being within the experimental error of one another (r1A = 0.0301 ±0.0153 g m-2 d-1, r95A = 0.0248 ±0.0125 g m-2 d-1, and r290A = 0.0389 ±0.0197 g m-2 d-1). Finally these results support the use of a chemical affinity based rate law to describe glass dissolution as a function of solution composition.« less
  • Our previous studies have found that the dissolution rates of West Valley high-level nuclear waste borosilicate glasses show a strongly non-linear dependence on glass composition. In certain composition ranges, near those of interest for nuclear waste disposal, very small changes in composition can produce drastic changes in leachate concentrations. In this paper we report on similar non-linear behavior found in fluorosilicate glasses developed for wastes from the DOE site at Fernald, Ohio. Glasses of each type have been extensively studied: for each type, a pair of glasses were chosen that are very close in composition but show drastically different dissolutionmore » kinetics, leached layer morphology, and precipitated crystalline phases.« less
  • In our previous studies on the optimization of glass compositions for high-level nuclear waste vitrification it was found that, over certain composition ranges, PCT leachate concentrations increased dramatically with very small changes in glass composition. The large differences that are observed between the leachate pH values for the {open_quotes}durable{close_quotes} and the {open_quotes}less-durable{close_quotes} glasses is one possible cause for this strongly non-linear glass composition effect; conversely, the pH difference may be merely another symptom. In this study, four simulated nuclear waste glasses (two of the less-durable and two of the durable types), were leached in both zwitterionic and inorganic buffer solutions,more » at fixed pH-values in the ranges of 7 to 12. The very different leaching behaviors of the two types of glasses persisted and, furthermore, different pH-dependence was found despite their very similar glass composition. This study suggests that the leachate pH difference observed between the less-durable and the durable glasses under uncontrolled pH conditions is not the major cause of the large difference of leaching behavior between those glasses. The normalized release ratios of soluble components (B, Li, Na) to Si show significant differences for the two types of glasses.« less
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