Recommended dispersing conditions for broths used in the preparation of uranium microspheres with carbon

•Adequate carbon dispersion in uranium spheres from the internal gelation process.•Use of viscosity to determine appropriate dispersion conditions for carbon blacks.•Recommended dispersion conditions for several carbon blacks prior to gelation.

Early preparations of uranium fuel kernels with carbon demonstrated the need for better dispersion of the carbon black in the aqueous feed solutions and in the subsequent microspheres. Therefore, the dispersing conditions for various carbon blacks were evaluated. A rheometer has proven to be a very useful tool in evaluation of dispersion conditions for carbon blacks (Black Pearl L and Raven 1000) with Tamol SN in the uranium and hexamethylenetetramine–urea feed solutions. The recommended dispersion conditions for Tamol SN were then used to make uranium microspheres with two carbon blacks. Optical images of these microspheres confirmed that the carbon was adequately dispersed, which supports the use of the viscosity measurements to determine appropriate carbon dispersion conditions.