Nuclear fuel pellet fabrication method

TiO2 powders which increase a sintering rate are mixed to UO2 powders having a high activity and they are pressed to form a columnar molding product. Then, SiO2-Al2O3 powders are mixed to UO2 powders having a low activity and they are pressed to form a cylindrical molding product. The columnar molding product is inserted to the cylindrical molding product and then they are pressed again to form a solid molding product, which is sintered in a reducing atmosphere. Since the crystal grains of powders mixed with TiO2 powders having a sintering promoting effect grow rapidly, the crystal grain size is increased. Since the crystal grain size at the center of the pellet is large, it takes much time for gaseous fissionable products that they are generated and reach the grain boundary, so that the amount of them released to the outside of the pellet can be decreased. Further, since the crystal grain size at the outer circumference is small and SiO2-Al2O3 is deposited, creep velocity is increased by boundary slipping. In this way, the performance in a high burnup degree region is improved. (N.H.)