An Infiltration Manufacturing Process for Nuclear Fuels

The Infiltrated Kernel Nuclear Fuel (IKNF) process deposits nuclear fuel into the naturally occurring porosity in graphite. IKNF consists of infiltrating uranyl nitrate dissolved in an organic solvent into the graphite and then heat-treating the sample at low (<300°C) temperatures to remove the solvent and convert the uranyl nitrate to UO₂. Complete conversion to UC₂ can then be accomplished by heating to temperatures higher than 3000°C. IKNF is extremely flexible: it is appropriate for very high temperature applications and heating the infiltrated product to intermediate temperatures (higher than 900°C) produces nuclear fuel with a range of chemistries in the U-C-O system (similar to the current US TRISO fuel). It is probable that the process can also be used to produce fuel containing transuranics. It is believed that IKNF will be less expensive, more robust and more suitable for on-line quality monitoring than current fuel fabrication method. Graphite infiltration involves a few, easily measurable and controllable variables. It is reproducible and predictable.