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Title: Analytical electron microscopy study of surface layers formed on the french SON68 nuclear waste glass during vapor hydration at 200{degree}C.

Abstract

Extensive solid-state characterization (AEM/SEM/HRTEM) was completed on six SON68 (inactive R7T7) waste glasses which were altered in the presence of saturated water vapor (200{sup o}C) for 22, 91, 241, 908, 1000, 1013, and 1021 days. The samples were examined by AEM in cross-section (lattice-fringe imaging, micro-diffraction, and quantitative thin-film EDS analysis). The glass monoliths were invariably covered by a thin altered rind, and the surface layer thickness increased with increasing time of reaction, ranging from 0.5 to 30 {mu}m in thickness. Six distinctive zones, based on phase chemistry and microstructure, were distinguished within the well-developed surface layers. Numerous crystalline phases such as analcime, gyrolite, tobermorite, apatite, and weeksite were identified on the surfaces of the reacted glasses as precipitates. The majority of the surface layer volume was composed of two basic structures that are morphologically and chemically distinct: The A-domain consisted of well-crystallized fibrous smectite aggregates; and the B-domain consisted of poorly-crystallized regions containing smectite, possibly montmorillonite, crystallites and a ZrO{sub 2}-rich amorphous silica matrix. The retention of the rare-earth elements, Mo, and Zr mostly occurred within the B-domain; while transition metal elements, such as Zn, Cr, Ni, Mn, and Fe, were retained in the A-domain. The element partitioning amongmore » A-domains and B-domains and recrystallization of the earlier-formed B-domains into the A-domain smectites were the basic processes which have controlled the chemical and structural evolution of the surface layer. The mechanism of surface layer formation during vapor hydration are discussed based on these cross-sectional AEM results.« less

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
OSTI Identifier:
942399
Report Number(s):
ANL/CMT/JA-31036
Journal ID: ISSN 0022-3115; JNUMAM; TRN: US200915%%531
DOE Contract Number:  
DE-AC02-06CH11357
Resource Type:
Journal Article
Journal Name:
J. Nucl. Mater.
Additional Journal Information:
Journal Volume: 254; Journal Issue: 2-3 ; Apr. 1998; Journal ID: ISSN 0022-3115
Country of Publication:
United States
Language:
ENGLISH
Subject:
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; AUGMENTATION; CHEMISTRY; ELECTRON MICROSCOPY; ELEMENTS; EVOLUTION; GLASS; HYDRATION; LAYERS; MICROSTRUCTURE; MONTMORILLONITE; RADIOACTIVE WASTES; RECRYSTALLIZATION; RETENTION; SILICA; SMECTITE; SURFACES; THICKNESS; TRANSITION ELEMENTS; VAPORS; VOLUME; WASTES; WATER VAPOR; ZEOLITES

Citation Formats

Gong, W L, Wang, L M, Ewing, R C, Vernaz, E, Bates, J K, Ebert, W L, Chemical Engineering, Univ. of New Mexico, and CEA-VALRHO,. Analytical electron microscopy study of surface layers formed on the french SON68 nuclear waste glass during vapor hydration at 200{degree}C.. United States: N. p., 1998. Web. doi:10.1016/S0022-3115(97)00349-8.
Gong, W L, Wang, L M, Ewing, R C, Vernaz, E, Bates, J K, Ebert, W L, Chemical Engineering, Univ. of New Mexico, & CEA-VALRHO,. Analytical electron microscopy study of surface layers formed on the french SON68 nuclear waste glass during vapor hydration at 200{degree}C.. United States. https://doi.org/10.1016/S0022-3115(97)00349-8
Gong, W L, Wang, L M, Ewing, R C, Vernaz, E, Bates, J K, Ebert, W L, Chemical Engineering, Univ. of New Mexico, and CEA-VALRHO,. Wed . "Analytical electron microscopy study of surface layers formed on the french SON68 nuclear waste glass during vapor hydration at 200{degree}C.". United States. https://doi.org/10.1016/S0022-3115(97)00349-8.
@article{osti_942399,
title = {Analytical electron microscopy study of surface layers formed on the french SON68 nuclear waste glass during vapor hydration at 200{degree}C.},
author = {Gong, W L and Wang, L M and Ewing, R C and Vernaz, E and Bates, J K and Ebert, W L and Chemical Engineering and Univ. of New Mexico and CEA-VALRHO,},
abstractNote = {Extensive solid-state characterization (AEM/SEM/HRTEM) was completed on six SON68 (inactive R7T7) waste glasses which were altered in the presence of saturated water vapor (200{sup o}C) for 22, 91, 241, 908, 1000, 1013, and 1021 days. The samples were examined by AEM in cross-section (lattice-fringe imaging, micro-diffraction, and quantitative thin-film EDS analysis). The glass monoliths were invariably covered by a thin altered rind, and the surface layer thickness increased with increasing time of reaction, ranging from 0.5 to 30 {mu}m in thickness. Six distinctive zones, based on phase chemistry and microstructure, were distinguished within the well-developed surface layers. Numerous crystalline phases such as analcime, gyrolite, tobermorite, apatite, and weeksite were identified on the surfaces of the reacted glasses as precipitates. The majority of the surface layer volume was composed of two basic structures that are morphologically and chemically distinct: The A-domain consisted of well-crystallized fibrous smectite aggregates; and the B-domain consisted of poorly-crystallized regions containing smectite, possibly montmorillonite, crystallites and a ZrO{sub 2}-rich amorphous silica matrix. The retention of the rare-earth elements, Mo, and Zr mostly occurred within the B-domain; while transition metal elements, such as Zn, Cr, Ni, Mn, and Fe, were retained in the A-domain. The element partitioning among A-domains and B-domains and recrystallization of the earlier-formed B-domains into the A-domain smectites were the basic processes which have controlled the chemical and structural evolution of the surface layer. The mechanism of surface layer formation during vapor hydration are discussed based on these cross-sectional AEM results.},
doi = {10.1016/S0022-3115(97)00349-8},
url = {https://www.osti.gov/biblio/942399}, journal = {J. Nucl. Mater.},
issn = {0022-3115},
number = 2-3 ; Apr. 1998,
volume = 254,
place = {United States},
year = {1998},
month = {4}
}