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Title: Low-temperature lithium diffusion in simulated high-level boroaluminosilicate nuclear waste glasses

Ion exchange is recognized as an integral, if underrepresented, mechanism influencing glass corrosion. However, due to the formation of various alteration layers in the presence of water, it is difficult to conclusively deconvolute the mechanisms of ion exchange from other processes occurring simultaneously during corrosion. In this work, an operationally inert non-aqueous solution was used as an alkali source material to isolate ion exchange and study the solid-state diffusion of lithium. Specifically, the experiments involved contacting glass coupons relevant to the immobilization of high-level nuclear waste, SON68 and CJ-6, which contained Li in natural isotope abundance, with a non-aqueous solution of 6LiCl dissolved in dimethyl sulfoxide at 90 °C for various time periods. The depth profiles of major elements in the glass coupons were measured using time-of-flight secondary ion mass spectrometry (ToF-SIMS). Lithium interdiffusion coefficients, DLi, were then calculated based on the measured depth profiles. The results indicate that the penetration of 6Li is rapid in both glasses with the simplified CJ-6 glass (D6Li ≈ 4.0-8.0 × 10-21 m2/s) exhibiting faster exchange than the more complex SON68 glass (DLi ≈ 2.0-4.0 × 10-21 m2/s). Additionally, sodium ions present in the glass were observed to participate in ion exchange reactions; however,more » different diffusion coefficients were necessary to fit the diffusion profiles of the two alkali ions. Implications of the diffusion coefficients obtained in the absence of alteration layers to the long-term performance of nuclear waste glasses in a geological repository system are also discussed.« less
Authors:
; ; ; ; ;
Publication Date:
OSTI Identifier:
1170086
Report Number(s):
PNNL-SA--104115
Journal ID: ISSN 0022-3093; 47580; AF5805010; TRN: US1500012
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Non-Crystalline Solids; Journal Volume: 405
Publisher:
Elsevier
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (United States). Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; LITHIUM; LITHIUM IONS; INDIUM IONS; SODIUM IONS; AQUEOUS SOLUTIONS; HIGH-LEVEL RADIOACTIVE WASTES; RADIOACTIVE WASTE DISPOSAL; MASS SPECTROSCOPY; ION MICROPROBE ANALYSIS; BOROSILICATE GLASS; BORON SILICATES; ALUMINIUM SILICATES; TEMPERATURE RANGE 0065-0273 K; DIFFUSION; DMSO; CORROSION; DEPTH; LAYERS; SIMULATION; WATER; ION EXCHANGE; TIME-OF-FLIGHT METHOD; ABUNDANCE; COMPLEXES; INTEGRALS; PERFORMANCE; SOLIDS; RADIOACTIVE WASTE FACILITIES lithium diffusion, nuclear waste glass, long-term corrosion, isotope tracking; Environmental Molecular Sciences Laboratory