Patent ID: 9679666
Date: 2017-06-13
CPC Classifications: G21C,Y02E

Claim:
1. A method of making a uranium dioxide nuclear fuel pellet, the method comprising: providing a mixture of uranium dioxide powder and additive powder consisting essentially of a Cr-containing compound or a Mo-containing compound; compressing the powder mixture to form a green pellet; and sintering the green pellet under reducing gas environment to convert at least part of the additive powder into liquid which permeates between grains of the uranium dioxide thereby forming micro-partitions consisting essentially of Cr or Mo and defining microcells in which the uranium dioxide is contained, the reducing gas environment comprising hydrogen gas and water vapor, wherein during sintering the green pellet is maintained to a first temperature under humid hydrogen gas and subsequently cooled to a second temperature under dry hydrogen gas having 0.1% moisture or less, the humid hydrogen gas containing more moisture than the dry hydrogen gas, the second temperature being lower than the first temperature.