Low-temperature sintering process for UO2 pellets in partially-oxidative atmosphere

Low-temperature sintering(LTS) experiments of UO2 pellets and their results were reported. Moreover, a routine process of LTS for UO2 pellets was primarily established. Being sintered at 1 400 °C for 3 h in a partially-oxidative atmosphere, the relative density of the pellet can be up to around 94%. Pellets with such a high density are of benefit for following-up reduction-sintering processes. Orthogonal test indicates that the importance of factors affecting the density decreases in the sequence of partial-oxidative sintering temperature and time, reduction-sintering time and temperature, and sintering atmosphere. It is found that it is helpful to introducing a small amount of water vapor into the sintering atmosphere during the latter stage. It is believed that it is the key factor to raise the O/U ratio of original powder in order to improve the properties of the low-temperature sintered pellets.