EFFECT OF PARTICLE-SHAPE AND DISTRIBUTION ON THERMAL AND ELECTRICAL CONDUCTIVITIES IN U3SI-AL DISPERSION FUELS

Two kinds of U3Si particles, longish-angular and spherical, have been prepared by comminution of a cast alloy and atomization of an inductio n melt, respectively. During the extrusion of U3Si-Al powder mixture t he longish-angular U3Si particles tend to align along the extrusion di rection and the spherical particles are randomly distributed. Along th e extrusion direction, the thermal diffusivity and electrical conducti vity of the comminution processed fuel are not much different from tho se of atomization processed fuel. Along the transverse direction, on t he other hand, the thermal diffusivity and electrical conductivity of the atomization processed fuel are appreciably higher than those of co mminution processed fuel. The conductivity difference between the two kinds of fuels has been explained by differences in microstructure, pa rticle shape and distribution, and compared with a theoretical analysi s based on a modified method of serial and parallel additions.