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Our research on activation product mobilization and transport studies the influence of oxidation on the mobilization of neutron activated fusion materials and the subsequent transport behavior of the mobilized material. We perform experiments and analyses in the area of activation product research and are currently studying:

• The influence of air or steam oxidation of fusion materials on the mobilization of radioactive activation products,
• The transport behavior (e.g. aerosol particle size) of the mobilized material,

VAPOR

The Volatilization of Activation Product Oxides Reactor (VAPOR), Figure 1, is a test facility for measuring the mobilization and transport of activation products as a result of air or steam oxidation of fusion materials.

Figure 1: Schematic of VAPOR Facility

The facility features:

• Heating by either an induction furnace or a tube furnace,
• Quantitative measurement of the mobilization of various elements via Inductive Coupled Plasma - Emission Spectroscopy (ICP-ES) or ICP-MS (mass spectroscopy),
• Characterization of particle sizes and chemistry via a cascade impactor, a laser-based particle size analyzer, scanning electron microscopy, and scanning transmission electron microscopy,
• Measurement of product gases via volumetric and gas chromatography methods,
• Measurement of temperatures within the range of 300 to 1800 °C,
• Operating environments that include air, steam, CO2, argon, and helium,
• Heating rates from 2 to 400 °C per minute,
• Gas flow rates of 0.01 to 25 liters per minute,
• Samples of various geometries and powders.

Materials that have been tested in the VAPOR facility include graphite; carbon-carbon fiber composites; austenitic and ferritic stainless steel; alloys of tungsten (Figures 2 through 5), niobium, vanadium, and copper; and beryllium.

Figure 2: Air Exposure of Tungsten

Figure 3: Mobilization Rates of Tungsten Activation Products

Figure 4: Aerosols Produced During Tungsten Oxidation

Figure 5: Tungsten Aerosol Particle Size Distribution from Cascade Impactor

FAST

The Fusion Aerosol Source Test (FAST), Figure 6, is a larger version of the VAPOR facility. FAST was constructed to produce and measure aerosols from materials that are typically found in fusion reactor systems. The primary goal of FAST is to study the mass concentration and surface area levels that decrease the detection limits of the mobilized material from the test section.

Figure 6: Schematic of FAST Facility

The key features of FAST are:

• Similar characterization capabilities to the VAPOR facility,
• Measurements of temperatures within the range of 300 to 1200 °C,
• Operating environments that include air, steam, and argon,
• Gas flow rates from 1 to 50 liters per minute

Materials that have been tested in the FAST facility include austenitic stainless steel, tungsten, and copper alloys. Samples are cylindrical tubes of 1 to 6 inch (2.5 to 15 cm) diameter and 40 inch (100 cm) length.