Carbon composites fusion reactor applications

Applied Sciences, Inc. has, in the past few years, used the fixed catalyst fiber to fabricate and analyze VGCF-reinforced composites which could be candidate materials for thermal management substrates in high density, high power electronic devices and space power system radiator fins and high performance applications such as plasma facing components in experimental nuclear fusion reactors. These composites include carbon/carbon (CC) composites, polymer matrix composites, and metal matrix composites (MMC). Measurements have been made of thermal conductivity, coefficient of thermal expansion (CTE), tensile strength, and tensile modulus. Representative results are described below. 

Carbon matrices are more suitable than polymers ones for applications at temperatures of 250 to 600°C. Above 600°C they are, however, (as are the C-fibers as such) only utilizable in inert atmospheres. C-fiber reinforced carbon matrix composites are particularly used in aircraft brakes, in fusion reactors and as a substitute for monolithic graphite. In addition they are utilized in the medical sector (implants), in furnace construction (heaters) and in energy conversion (heat exchangers). The market for carbon fiber/carbon matrix composites in 1993 was estimated to be ca. 250 t. 

Carbon-based materials have been shown to be compatible with molten salts at temperatures of 1000°C, and for graphite up to 1400°C. Carbon-carbon composites which are currently being considered for fusion and for high-temperature reactors (e.g., in-core applications such as control rods, straps, etc.) are therefore also an option for the MSR and MSFR. For these materials there are nevertheless uncertainties in the joining technology and large-scale development work and demonstrations would be needed for their application in safety-related components. 

In Japan, the studies were facilitated by the access to the fusion (JT-60) and fission neutron reactor (JMTR, HTTR), for quite large samples, and by the know-how of Japanese industry in the field of carbon fibers and composites. PAN-based C fibers, instead of pitch-based ones (for 2D composites, with an ex-pitch C matrix), were chosen for irradiation tests (for fission application), since a larger fracture load and deformation could be obtained [34]. By the end of the 1990s, the main material studied in Japan was a 2D PAN-based C fiber/mix (ex-phenolic - - ex-pitch) C matrix material... 

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