The present invention relates to nuclear fuel compositions including uranium dioxide with integral fuel burnable absorber, and triuranium disilicide and a composite of uranium mononitride and triuranium disilicide with or without integral fuel burnable absorber, and methods of sintering these compositions. The sintering is conducted using SPS/FAST apparatus and techniques. The sintering time and temperature is reduced using SPS/FAST as compared to conventional sintering methods for nuclear fuel compositions. The nuclear fuel compositions of the present invention are particularly useful in light water reactors.