Abstract
Fabrication of uranium oxicarbide (UCO) microspheres, a component of TRISO fuel particles for high temperature nuclear power systems, is based on the internal gelation process of uranium salts in presence of carbon black. In order to obtain a high quality product, carbon black should remain dispersed during all phases of the gelation process. In this study, the surface and structural properties of several commercial carbon black materials, and their use in combination with ionic and non-ionic dispersing agents was examined with the goal of finding optimal conditions for stabilizing submicron-sized carbon black dispersions. Traditional methods for stabilizing dispersions, based on the use of dispersing agents, failed to stabilize carbon dispersions against large pH variations, typical for the internal gelation process. An alternate dispersing method was proposed, based on using surface-modified carbons functionalized with strongly ionizing surface groups (sodium sulfonate). With a proper choice of surface modifiers, these advanced carbons disperse easily to particles in the range of 0.15�V0.20 ��m and the dispersions remain stable during the conditions of internal gelation.
