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Oxidative Alteration of Spent Fuel in a Silica-Rich Environment: SEM/AEM Investigation and Geochemical Modeling.

DE2002752105

Publication Date	2000
Personal Author	Wang, Y.; Xu, H.
Page Count	9
Abstract	Correctly identifying the possible alteration products and accurately predicting their occurrence in a repository-relevant environment are the key for source-term calculations in a repository performance assessment. Uraninite in uranium deposits has long been used as a natural analog to spent fuel in a repository because of their chemical and structural similarity. In this paper, a SEIWAEM investigation has been conducted on a partially alterated uraninite sample from a uranium ore deposit .of Shinkolobwe of Congo. The mineral formation sequences were identified: uraninite yields uranyl hydrates yields uranyl silicates yields Ca-uranyl silicates or uraninite yields uranyl silicates yields Ca-uranyl silicates. Reaction-path calculations were conducted for the oxidative dissolution of spent fiel in a representative Yucca Mountain groundwater. The predicted sequence is in general consistent with the SEM observations. The calculations also show that uranium carbonate minerals are unlikely to become major volubility-controlling mineral phases in a Yucca Mountain environment. Some discrepancies between model predictions and field observations are observed. Those discrepancies may result from poorly constrained thermodynamic data for uranyl silicate minerals.
Keywords	Oxidative alteration Spent fuels Investigations Uraninite Geochemical modeling Silica-rich environments Repository-relevant environments Source-term calculations Repository performance assessments SEM/AEM
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	Sandia National Labs., Albuquerque, NM.; New Mexico Univ., Albuquerque. Dept. of Earth and Planetary Sciences.; Department of Energy, Washington, DC.
Supplemental Notes	Prepared in cooperation with New Mexico Univ., Albuquerque. Dept. of Earth and Planetary Sciences. Sponsored by Department of Energy, Washington, DC.
Document Type	Technical Report
NTIS Issue Number	200218

Oxidative Alteration of Spent Fuel in a Silica-Rich Environment: SEM/AEM Investigation and Geochemical Modeling.

Oxidative Alteration of Spent Fuel in a Silica-Rich Environment: SEM/AEM Investigation and Geochemical Modeling.
DE2002752105

Publication Date	2000
Personal Author	Wang, Y.; Xu, H.
Page Count	9
Abstract	Correctly identifying the possible alteration products and accurately predicting their occurrence in a repository-relevant environment are the key for source-term calculations in a repository performance assessment. Uraninite in uranium deposits has long been used as a natural analog to spent fuel in a repository because of their chemical and structural similarity. In this paper, a SEIWAEM investigation has been conducted on a partially alterated uraninite sample from a uranium ore deposit .of Shinkolobwe of Congo. The mineral formation sequences were identified: uraninite yields uranyl hydrates yields uranyl silicates yields Ca-uranyl silicates or uraninite yields uranyl silicates yields Ca-uranyl silicates. Reaction-path calculations were conducted for the oxidative dissolution of spent fiel in a representative Yucca Mountain groundwater. The predicted sequence is in general consistent with the SEM observations. The calculations also show that uranium carbonate minerals are unlikely to become major volubility-controlling mineral phases in a Yucca Mountain environment. Some discrepancies between model predictions and field observations are observed. Those discrepancies may result from poorly constrained thermodynamic data for uranyl silicate minerals.
Keywords	Oxidative alteration Spent fuels Investigations Uraninite Geochemical modeling Silica-rich environments Repository-relevant environments Source-term calculations Repository performance assessments SEM/AEM
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	Sandia National Labs., Albuquerque, NM.; New Mexico Univ., Albuquerque. Dept. of Earth and Planetary Sciences.; Department of Energy, Washington, DC.
Supplemental Notes	Prepared in cooperation with New Mexico Univ., Albuquerque. Dept. of Earth and Planetary Sciences. Sponsored by Department of Energy, Washington, DC.
Document Type	Technical Report
NTIS Issue Number	200218