Experimental study of the effective thermal conductivity of a packed bed as a temperature control mechanism for ITER ceramic breeder blanked designs

For an ITER (International Thermonuclear Experimental Reactor) ceramic breeding blanket, the breeder temperature must be kept above about 400 degrees C for adequate tritium release, while low coolant temperatures are desired to maximize reliability. A thermal resistance gap between the coolant and solid breeder to allow their operating temperatures to be optimized for the ITER is proposed. The concept provides operational flexibility to accommodate ITER power variation through control of the thermal conductance of the gap. The control mechanism provides the ability to maintain the breeder within the operating limits defined by the minimum temperature for tritium release and the maximum temperature, which is usually based on sintering. Sintering also retards tritium release, thereby increasing the blanket tritium inventory. Experimental studies of the effective thermal conductivity of a metallic packed bed are presented.<
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