两步烧结制备细晶核燃料的研究

Study on Preparation of Fine Crystal Nuclear Fuel byTwo-Step Sintering

为制备高燃耗结构的细晶核燃料,以UO2陶瓷为研究对象,通过设置实验变量,探究了成型压力、烧结温度对UO2陶瓷性能的影响,探讨两步法制备细晶UO2陶瓷燃料的可行性。结果表明,采用两步烧结制备得到的UO2陶瓷晶粒尺寸相对于传统烧结工艺(平均晶粒尺寸约23.8μm)明显降低,部分晶粒已经达到了亚微米级别;试样晶粒尺寸分布不均匀,小晶粒尺寸小于500 nm,大晶粒尺寸在1~5μm之间;第一步烧结温度(T1)越低,晶粒尺寸越小,但同时晶粒尺寸分布越不均匀;成型压力与试样最终烧结密度成正相关关系,成型压力越大,试样密度提升幅度越大。

To prepare the fine grain nuclear fuel with high burnup structure,uranium dioxide was taking as the research object.By setting experimental variables,the effect of molding pressure and sintering temperature reactor on submicron UO2 fuel pellets was investigated.The feasibility of preparing fine crystal nuclear fuel by two-step method was explored.The results show that the grain size of the UO2 pellets prepared by the two-step process is significantly lower than that of the conventional UO2 sintering process(23.8μm).The grain size distribution of the sample is not uniform,the small grain size is less than 500 nm,and the large grain size is between 1~5μm.The lower the temperature of T1,the smaller the grain size,but more uneven the grain size distribution.The molding pressure is positively correlated with the sintered density of the pellet.The higher the molding pressure,the smaller the density increasing of the pellet.