Corrosion Characteristics of Titanium Alloys in Multi-Ionic Environments

2003 ◽  
Author(s):  
Lana L. Wong ◽  
John C. Estill ◽  
David V. Fix ◽  
Rau´l B. Rebak
Keyword(s):  
Corrosion Rate ◽  
Nuclear Waste ◽  
Electrolyte Solutions ◽  
Localized Corrosion ◽  
Nuclear Waste Repository ◽  
Liquid Phases ◽  
High Level Nuclear Waste ◽  
Engineered Barriers ◽  
Titanium Grade ◽  
High Level

Yucca Mountain (Nevada) is designated as a high-level nuclear waste repository. The nuclear waste will be isolated by a series of engineered barriers. The metallic engineered barriers will consist of a double-wall container with a detached drip shield. The material for the external wall of the container is Alloy 22, a corrosion-resistant Ni-Cr-Mo alloy. Titanium grade 7 has been proposed for the drip shield. Ti alloys are highly resistant to all forms of corrosion due to the formation of a stable, protective and strongly adherent oxide film. The aim of this research was to characterize the general and localized corrosion behavior of Ti Gr 7, 16 and 12 in simulated concentrated ground waters. Welded and non-welded coupons were exposed for up to 5 years to the vapor and liquid phases of acidic and alkaline multi-ionic solutions at 60°C and 90°C. This paper describes the results obtained after approximately 2-1/2- to 5-1/2-year exposure to the testing electrolyte solutions. In general, the highest corrosion rate was obtained for Ti Gr 12; however, in all of the tested conditions, the corrosion rate was generally lower than 100 nm/yr. For all alloys, the highest corrosion rate was obtained in the concentrated alkaline solution.

Comparison of Granite, Tuff, and Basalt as Geologic Media for Long-Term Storage of High-Level Nuclear Waste

1990 ◽  
Vol 212 ◽  
Author(s):  
D. E. Grandstaff ◽  
V. J. Grassi ◽  
A. C. Lee ◽  
G. C. Ulmer
Keyword(s):  
Nuclear Waste ◽  
Nuclear Waste Repository ◽  
Long Term Storage ◽  
Hydrothermal Experiments ◽  
Ion Activity ◽  
Activity Ratios ◽  
High Level Nuclear Waste ◽  
High Level ◽  
Term Storage

ABSTRACTSystematic differences in pH, cation/proton ion activity ratios, and redox have been observed between solutions produced in rock-water hydrothermal experiments with tuff, granite, and basalt. Stable pH values in tuff-water experiments may be as much as 1.5 pH units more acidic than basalt-water experiments at the same temperature and ionic strength. Redox (log fO2) values in 300°C tuff experiments are 4–7 orders of magnitude more oxidizing than basalt experiments and ca. 4 log units more oxidizing than the magnetite-hematite buffer. Such fluid differences could significantly affect the performance of a high-level nuclear waste repository and should be considered in repository design and siting.

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