Nuclear fuel particles

Coated nuclear fuel particles are made by first pyrolytically depositing low density carbon onto fuel cores and thereafter depositing a fission-product retentive, higher density exterior coating. In the improvement, cores of uranium, thorium or plutonium oxides are coated by co-depositing silicon carbide or zirconium carbide along with the low density pyrocarbon to create a uniform dispersion. Silicon or zirconium is deposited in an amount equal to at least about one atom for each fission anticipated during the fuel lifetime