Method of manufacturing nuclear fuel pellet

It has been difficult to manufacture nuclear fuel pellets having a sufficiently great crystal grain size and soft crystal grain boundary, that is, to attain low nuclear fission products releasing rate and improvement for PCI (pellet-cladding tube mechanical interaction) characteristics simultaneously. Then, intermetallic compounds or mixed oxides having a lower eutectic point than the higher sintering temperature are heated at a temperature higher than the eutectic point with a predetermined composition ratio, to form mono-liquid phase eutectics. Homogeneous powders obtained by cooling and pulverizing them are added to nuclear fuel oxide powders. After molding dust cores, when they are sintered at a temperature higher than the eutectic temperature of the added mixture, surface reactions between fuel powders are promoted by a liquid phase sintering mechanism, to promote the growth of crystal grains. Diffusion distance to the crystal grain boundary is increased and creep characteristics can be improved due to the increase of the grain size and softening, to decrease the releasing rate of nuclear fission products from the pellets. (N.H.)