Preparation of UO2 Pellets with Large Grain Containing Chromium
The UO2 pellets with large grain and high thermal conductivity is an ideal nuclear fuel pellets with high burnup.Ac-cording to the design requirements,trace substances Al2 O3 and Cr2 O3 should be added in UO2 powder and then the fuel pellet is prepared in a powder metallurgy manner so as to ensure that the grain size is over 30μm and the density is 96.5%～97%T.D.At the same time,the residual amount of Cr in the pellet should be 0.06 wt%～0.1wt%in order to improve the thermal conductivity of the pellet.In the preparation process,the optimal addition amount of the two substances is determined by single addition method,and then the appropriate powder pretreatment technology is selected for the mixed addition test.The results show that by adding 0.008wt%～0.01wt%Al2 O3 powder and 0.2wt%～0.3wt%Cr2 O3 powder respectively,and using the method of coating Cr2 O3 with the pelletizing powder,the UO2 pellets with large grain containing chromium can be obtained,whose grain size can reach 43.3 μm,the density is 96.8%T.D,and the residual amount of Cr is 0.0864wt%.
NETL
NSTL
万方数据
