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Title: Novel Zoned Waste-forms for High-Priority Radionuclide Waste Streams.

Abstract

This report describes the potential of a novel class of materials--a-ZrW 2 0 8 , Zr 2 WP 2 0 12 , and related compounds that contract upon amorphization as possible radionuclide waste-forms. The proposed ceramic waste-forms would consist of zoned grains, or sintered ceramics with center- loaded radionuclides and barren shells. Radiation-induced amorphization would result in core shrinkage but would not fracture the shells or overgrowths, maintaining isolation of the radionuclide. In this report, we have described synthesis techniques to produce phase-pure forms of the materials, and how to fully densify those materials. Structural models for the materials were developed and validated using DFPT approaches, and radionuclide substitution was evaluated; U(IV), Pu(IV), Tc(IV) and Tc(VII) all readily substitute into the material structures. MD modeling indicated that strain associated with radiation-induced amorphization would not affect the integrity of surrounding crystalline materials, and these results were validated via ion beam experimental studies. Finally, we have evaluated the leach rates of the barren materials, as determined by batch and flow-through reactor experiments. ZrW 2 0 8 leaches rapidly, releasing tungstate while Zr is retained as a solid oxide or hydroxide. Tungsten release rates remain elevated over time and are highly sensitive tomore » contact times, suggesting that this material will not be an effective waste-form. Conversely, tungsten releases rates from Zr2WP2012 rapidly drop, show little dependence on short-term changes in fluid contact time, and in over time, become tied to P release rates. The results presented here suggest that this material may be a viable waste-form for some hard-to-handle radionuclides such as Pu and Tc. ACKNOWLEDGEMENTS The authors acknowledge the contributions to this report from Sandia National Laboratories researchers Steven Meserole, Mark Rodriguez, Clay Payne, Tim Boyle, Nate Padilla, Khalid Hattar, Anthony Monterrosa, Trevor Clark, and Daniel Perry.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1569156
Report Number(s):
SAND2019-11295
679697
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English

Citation Formats

Bryan, Charles R., Gordon, Margaret Ellen, Greathouse, Jeffery A., Weck, Philippe F, and Kim, Eunja. Novel Zoned Waste-forms for High-Priority Radionuclide Waste Streams.. United States: N. p., 2019. Web. doi:10.2172/1569156.
Bryan, Charles R., Gordon, Margaret Ellen, Greathouse, Jeffery A., Weck, Philippe F, & Kim, Eunja. Novel Zoned Waste-forms for High-Priority Radionuclide Waste Streams.. United States. doi:10.2172/1569156.
Bryan, Charles R., Gordon, Margaret Ellen, Greathouse, Jeffery A., Weck, Philippe F, and Kim, Eunja. Sun . "Novel Zoned Waste-forms for High-Priority Radionuclide Waste Streams.". United States. doi:10.2172/1569156. https://www.osti.gov/servlets/purl/1569156.
@article{osti_1569156,
title = {Novel Zoned Waste-forms for High-Priority Radionuclide Waste Streams.},
author = {Bryan, Charles R. and Gordon, Margaret Ellen and Greathouse, Jeffery A. and Weck, Philippe F and Kim, Eunja},
abstractNote = {This report describes the potential of a novel class of materials--a-ZrW 2 0 8 , Zr 2 WP 2 0 12 , and related compounds that contract upon amorphization as possible radionuclide waste-forms. The proposed ceramic waste-forms would consist of zoned grains, or sintered ceramics with center- loaded radionuclides and barren shells. Radiation-induced amorphization would result in core shrinkage but would not fracture the shells or overgrowths, maintaining isolation of the radionuclide. In this report, we have described synthesis techniques to produce phase-pure forms of the materials, and how to fully densify those materials. Structural models for the materials were developed and validated using DFPT approaches, and radionuclide substitution was evaluated; U(IV), Pu(IV), Tc(IV) and Tc(VII) all readily substitute into the material structures. MD modeling indicated that strain associated with radiation-induced amorphization would not affect the integrity of surrounding crystalline materials, and these results were validated via ion beam experimental studies. Finally, we have evaluated the leach rates of the barren materials, as determined by batch and flow-through reactor experiments. ZrW 2 0 8 leaches rapidly, releasing tungstate while Zr is retained as a solid oxide or hydroxide. Tungsten release rates remain elevated over time and are highly sensitive to contact times, suggesting that this material will not be an effective waste-form. Conversely, tungsten releases rates from Zr2WP2012 rapidly drop, show little dependence on short-term changes in fluid contact time, and in over time, become tied to P release rates. The results presented here suggest that this material may be a viable waste-form for some hard-to-handle radionuclides such as Pu and Tc. ACKNOWLEDGEMENTS The authors acknowledge the contributions to this report from Sandia National Laboratories researchers Steven Meserole, Mark Rodriguez, Clay Payne, Tim Boyle, Nate Padilla, Khalid Hattar, Anthony Monterrosa, Trevor Clark, and Daniel Perry.},
doi = {10.2172/1569156},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2019},
month = {9}
}