Weak-acid ion-exchange resins have been found to provide a practical method for fabricating uranium-containing HTGR fuel kernels. Two steps, thermal decomposition or carbonization and carbothermic reduction of UO/sub 2/ or conversion, are required in the manufacture of these kernels. The property variations during carbonization of uranium-loaded weak-acid resin-derived fuel proceeds in a manner closely analogous to its thermogravimetric characteristics, particularly the weight loss, volume loss, carbon-to-uranium ratio, density, and particle size. The heating rate through the critical portion of the thermogravimetric curve closely controls the resultant weight loss, volume loss, density, carbon-to-uranium ratio, and subsequent thermal behavior. The optimum carbonization cycle derived dictates a heating rate of 2/sup 0/C/min from 350 to 440/sup 0/C, and the maximum practicable rate outside of this range. The conversion of the carbonized material is predictable from classical bulk thermodynamics for removal of carbon monoxide from UO/sub 2/ + C. Relative phase compositions of UO/sub 2/, UC/sub 2/ and UC/sub 1-x/O/sub x/ can be controlled by adjusting conversion conditions. Agglomeration during conversion can be controlled by lowering the carbonization rate and/or conversion temperature and increasing gas flow. During this process Duolite C-464 resin appears more resistant to sticking than does Amberlite IRC-72.
