Fabrication of mixed uranium-plutonium carbide fuel pellets for FBTR from reject pellets and process scraps by dry route

Mixed uranium-plutonium carbide fuel pellets of compositions 70%PuC-30%UC (Mk I) and 55%PuC-45%UC (Mk II) encapsulated in stainless steel clad tubes are being used as driver fuel for Fast Breeder Test Reactor at Kalpakkam. In B.A.R.C., the manufacture of fuel pins is being carried out for almost twenty five years in several fabrication campaigns to meet the fuel requirements. Production of mixed uranium-plutonium carbide pellets are carried out in batches of one kilogram and the process flow sheet involves vacuum carbothermic reduction of UO₂, PuO₂ and graphite mixture tablets for synthesis of carbide clinkers followed by milling, cold compaction and sintering. The fabrication is carried out in glove boxes maintained in high purity nitrogen atmosphere with less than 25 ppm of oxygen and moisture impurities, since the carbide powders are pyrophoric in nature and are also susceptible to oxidation and hydrolysis