National Technical Reports Library

The National Technical Information Service acquires, indexes, abstracts, and archives the largest collection of U.S. government-sponsored technical reports in existence. The NTRL offers online, free and open access to these authenticated government technical reports. Technical reports and documents in its repository may be available online for free either from the issuing federal agency, the U.S. Government Publishing Office’s Federal Digital System website, or through search engines.

Details

Oxidation and Volatilization from Tantalum Alloy T-222 During Air Exposure.

DE2001776430

Publication Date	2000
Personal Author	Smolik, G. R.; Petti, D. A.; Sharpe, J. P.; Schuetz, S. T.
Page Count	35
Abstract	Tantalum alloys are one of the refractory metals with renewed consideration for high temperatures in fusion reactor applications. Tantalum alloys perform well in protective environments but oxidized readily in gases containing higher oxygen levels. In addition, the radioactive isotope Ta-182 would be produced in tantalum and could be a significant contributor to dose if mobilized. Other isotopes of importance are produced from tungsten and hafnium. Mobilization of activated products during an accident with air ingress is therefore a safety issue. In this study, we measured the extent of oxidation and mobilization from tantalum alloy T-222 oxidized in flowing air between 500 and 1200 C. This alloy nominally contains 10 wt% tungsten, 2.5 wt% hafnium and 0.01 wt% carbon. We found that the mobilization of Ta and Hf was closely linked to the occurrence of oxide spalling. These elements showed no migration from the test chamber. Some W was mobilized by volatilization as evidenced by transport from the chamber. Tungsten volatilization could occur primarily during initial stages of oxidation before an oxide scale forms and impedes the process. The mobilization of Ta and W are presented in terms of the mass flux (g/m 2 -h) as a function of test temperature. These measurements along with specific designs, activation calculations, and accident scenarios provide information useful for dose calculations of future fusion devices.
Keywords	Air Oxidation Tantalum alloys Alloys Carbon Evaporation Hafnium Tantalum Thermonuclear reactors Tungsten Fusion reactors Refractory metals Exposure
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	Idaho Operations Office (AEC), Idaho Falls.; Department of Energy, Washington, DC.
Document Type	Technical Report
NTIS Issue Number	200125
Contract Number	AC07-99ID13727

Oxidation and Volatilization from Tantalum Alloy T-222 During Air Exposure.

Oxidation and Volatilization from Tantalum Alloy T-222 During Air Exposure.
DE2001776430

Publication Date	2000
Personal Author	Smolik, G. R.; Petti, D. A.; Sharpe, J. P.; Schuetz, S. T.
Page Count	35
Abstract	Tantalum alloys are one of the refractory metals with renewed consideration for high temperatures in fusion reactor applications. Tantalum alloys perform well in protective environments but oxidized readily in gases containing higher oxygen levels. In addition, the radioactive isotope Ta-182 would be produced in tantalum and could be a significant contributor to dose if mobilized. Other isotopes of importance are produced from tungsten and hafnium. Mobilization of activated products during an accident with air ingress is therefore a safety issue. In this study, we measured the extent of oxidation and mobilization from tantalum alloy T-222 oxidized in flowing air between 500 and 1200 C. This alloy nominally contains 10 wt% tungsten, 2.5 wt% hafnium and 0.01 wt% carbon. We found that the mobilization of Ta and Hf was closely linked to the occurrence of oxide spalling. These elements showed no migration from the test chamber. Some W was mobilized by volatilization as evidenced by transport from the chamber. Tungsten volatilization could occur primarily during initial stages of oxidation before an oxide scale forms and impedes the process. The mobilization of Ta and W are presented in terms of the mass flux (g/m 2 -h) as a function of test temperature. These measurements along with specific designs, activation calculations, and accident scenarios provide information useful for dose calculations of future fusion devices.
Keywords	Air Oxidation Tantalum alloys Alloys Carbon Evaporation Hafnium Tantalum Thermonuclear reactors Tungsten Fusion reactors Refractory metals Exposure
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	Idaho Operations Office (AEC), Idaho Falls.; Department of Energy, Washington, DC.
Document Type	Technical Report
NTIS Issue Number	200125
Contract Number	AC07-99ID13727