HTGR Fuel Recycle Development Program (189A OHO45). Fuel Refabrication, Task 500. Rate-Controlling Factors in the Carbothermic Preparation of UO sub 2 --UC Sub 2 --C Microspheres

摘要

Rate controlling factors in the conversion of UO sub 2 + C microspheres to UC sub 2 + C were investigated using a 13-cm-dia fluidized bed furnace. X-ray diffraction, ion microprobe, and microstructural examination revealed that the conversion of UO sub 2 to UC sub 2 began at the surface of the microsphere and progressed toward the central unreacted core. Kinetic models for solid state reactions in spheres were evaluated by using quantitative mass spectrometric data on the rae of evolution of carbon monoxide during conversion. This analysis revealed that the rate of conversion was controlled by reaction at the outer surface of the microsphere. Also, decreased partial pressures of carbon monoxide were found to accelerate the rate of reaction. (ERA citation 04:021693)