Thermal Conductivity of Beds of Coated Fuel Particles

The thermal conductivity of loose, pyrolytic carbon-coated fuel particles in helium was studied at temperatures from 1800 to 2700°F using a convenient comparative technique. The conductivities of coated particles with both 150- and 795-µm overall diameters were shown to rise and then remain constant as the helium pressure was increased to 4 atm. Measurements using particles with various coating thicknesses and structures indicated that bed conductivity was relatively insensitive to the properties of the coating.