Oxidation and volatilization of a niobium alloy. Fusion Safety Program/Activation Products Task

Technical Report · Wed Jul 01 04:00:00 EDT 1992

DOI:https://doi.org/10.2172/10185771· OSTI ID:10185771

Smolik, G R; McCarthy, K A

This report presents the findings from a preliminary investigation into oxidation and volatilization characteristics of a niobium alloy. Niobium is a candidate alloy for use in plasma facing components (PFCS) in experimental fusion reactors like the Intemational Thermonuclear Experimental Reactor (ITER). An experimental alloy was tailored to simulate small changes in chemistry which could result from transmutations from irradiation. The alloy was exposed in air and steam between 800{degree}C and 1200{degree}C. Volatilized products and hydrogen were collected and measured. Post-test examinations were also performed on the samples to determine the amount of material loss during the exposures. The obtained measurements of volatilization flux (g/m{sup 2}-s), hydrogen generation rates (liters/m{sup 2}-s), and recession rates (mm/s) are data which can be used for safety analyses and material performance to predict consequences which may result from an accident involving the ingress of air or steam into the plasma chamber of fusion reactor. In our volatility tests, only molybdenum and niobium were found at release levels above the detection limit. Although molybdenum is present at only 0.12 wt%, the quantities of this element volatilized in air are nearly comparable to the quantities of niobium released. The niobium release in steam is only three to four times higher than that of molybdenum in steam. The hydrogen production of the niobium alloy is compared with other PFC materials that we have tested, specifically, beryllium, graphite, and a tunesten alloy. At high temperatures, the hydrogen production rate of the niobium alloy is among the lowest of these materials, significantly lower than beryllium. To understand what this means in an accident situation, modeling is necessary to predict temperatures, and therefore total hydrogen production. The INEL is currently doing this modeling.

• Research Organization: EG and G Idaho, Inc., Idaho Falls, ID (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC07-76ID01570
• OSTI ID: 10185771
• Report Number(s): EGG-FSP--10341; ON: DE93001927
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104
360105
360106
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700480
COMPONENT DEVELOPMENT
CORROSION AND EROSION
DIVERTORS
EVAPORATION
FIRST WALL
HYDROGEN PRODUCTION
ITER TOKAMAK
MATERIALS STUDIES
NIOBIUM BASE ALLOYS
OXIDATION
PHYSICAL PROPERTIES
PHYSICAL RADIATION EFFECTS
PRESSURE DEPENDENCE
RADIATION EFFECTS
SAFETY ANALYSIS
TEMPERATURE DEPENDENCE
THERMONUCLEAR REACTOR MATERIALS