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Title: Kinetics of oxyapatite [Ca2Nd8(SiO4)6O2] and powellite [(Ca,Sr,Ba)MoO4] dissolution in glass-ceramic nuclear waste forms in acidic, neutral, and alkaline conditions

Abstract

Solidification of chemically complex aqueous waste streams from used nuclear fuel reprocessing is achievable with glass ceramics. Glass ceramics are a desirable waste form because higher waste loading is achievable compared to borosilicate glasses. Additionally, crystalline phases with similar chemistry are more durable than their amorphous counterpart. However, during glass ceramic fabrication, mechanical stresses at crystal-glass interfaces, which are caused by thermal expansion mismatch during cooling, create locales where water is capable of accessing and reacting with the various phases in the glass ceramic and releasing radionuclides into the aqueous phase. In the present work, we build on previous chemical durability investigations of a glass-ceramic containing crystalline powellite [(Ca,Sr,Ba)MoO4] and oxyapatite [Ca2Nd8(SiO4)6O2] secondary phases. The individual crystalline and bulk glass phases have been fabricated separately and the corrosion behavior has been investigated with single-pass flow-through (SPFT) testing at 90 °C in buffered pH(RT) 4, 7, 9 and pH 11 solutions and with the static product consistency test – B (PCT-B). The results demonstrate the varying dissolution kinetics of the individual phases in the range of pH studies. The consequence of the varying dissolution kinetics are described with a conceptual model of glass-ceramic dissolution mechanisms.

Authors:
ORCiD logo; ORCiD logo; ; ; ORCiD logo;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1499218
Report Number(s):
PNNL-SA-138113
Journal ID: ISSN 0022-3115
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Journal of Nuclear Materials
Additional Journal Information:
Journal Volume: 515; Journal Issue: C; Journal ID: ISSN 0022-3115
Publisher:
Elsevier
Country of Publication:
United States
Language:
English

Citation Formats

Neeway, James J., Asmussen, R. Matthew, McElroy, Erin M., Peterson, Jacob A., Riley, Brian J., and Crum, Jarrod V. Kinetics of oxyapatite [Ca2Nd8(SiO4)6O2] and powellite [(Ca,Sr,Ba)MoO4] dissolution in glass-ceramic nuclear waste forms in acidic, neutral, and alkaline conditions. United States: N. p., 2019. Web. doi:10.1016/j.jnucmat.2018.12.043.
Neeway, James J., Asmussen, R. Matthew, McElroy, Erin M., Peterson, Jacob A., Riley, Brian J., & Crum, Jarrod V. Kinetics of oxyapatite [Ca2Nd8(SiO4)6O2] and powellite [(Ca,Sr,Ba)MoO4] dissolution in glass-ceramic nuclear waste forms in acidic, neutral, and alkaline conditions. United States. doi:10.1016/j.jnucmat.2018.12.043.
Neeway, James J., Asmussen, R. Matthew, McElroy, Erin M., Peterson, Jacob A., Riley, Brian J., and Crum, Jarrod V. Fri . "Kinetics of oxyapatite [Ca2Nd8(SiO4)6O2] and powellite [(Ca,Sr,Ba)MoO4] dissolution in glass-ceramic nuclear waste forms in acidic, neutral, and alkaline conditions". United States. doi:10.1016/j.jnucmat.2018.12.043.
@article{osti_1499218,
title = {Kinetics of oxyapatite [Ca2Nd8(SiO4)6O2] and powellite [(Ca,Sr,Ba)MoO4] dissolution in glass-ceramic nuclear waste forms in acidic, neutral, and alkaline conditions},
author = {Neeway, James J. and Asmussen, R. Matthew and McElroy, Erin M. and Peterson, Jacob A. and Riley, Brian J. and Crum, Jarrod V.},
abstractNote = {Solidification of chemically complex aqueous waste streams from used nuclear fuel reprocessing is achievable with glass ceramics. Glass ceramics are a desirable waste form because higher waste loading is achievable compared to borosilicate glasses. Additionally, crystalline phases with similar chemistry are more durable than their amorphous counterpart. However, during glass ceramic fabrication, mechanical stresses at crystal-glass interfaces, which are caused by thermal expansion mismatch during cooling, create locales where water is capable of accessing and reacting with the various phases in the glass ceramic and releasing radionuclides into the aqueous phase. In the present work, we build on previous chemical durability investigations of a glass-ceramic containing crystalline powellite [(Ca,Sr,Ba)MoO4] and oxyapatite [Ca2Nd8(SiO4)6O2] secondary phases. The individual crystalline and bulk glass phases have been fabricated separately and the corrosion behavior has been investigated with single-pass flow-through (SPFT) testing at 90 °C in buffered pH(RT) 4, 7, 9 and pH 11 solutions and with the static product consistency test – B (PCT-B). The results demonstrate the varying dissolution kinetics of the individual phases in the range of pH studies. The consequence of the varying dissolution kinetics are described with a conceptual model of glass-ceramic dissolution mechanisms.},
doi = {10.1016/j.jnucmat.2018.12.043},
journal = {Journal of Nuclear Materials},
issn = {0022-3115},
number = C,
volume = 515,
place = {United States},
year = {2019},
month = {3}
}