First, in accordance with the traditional approach to the preparation
of nuclear fuel for pressurized water reactors, UO2 pellets
with the ration of O/U ¼ 2.10 are prepared with the raw material of
ammonium diuranate (ADU, 235U content ¼ 0.2 at%). The UO2
pellets are broken into UO2 powder with the particle size
1e2 mm.The UO2 powder was dried at 350 C for 2.5 h and 99.9%
Gd2O3 powder with the particle size 1 mm(Ganzhou holmium xin
new materials co.,LTD) was dried at 550 C for 2 h. Based on the
mass fractions of Gd2O3 in UO2-10 wt% Gd2O3 fuel pellets, a certain
amount of dry powder (90 g UO2 powder, 10 g Gd2O3 powder) was
put into the dissolving tank together with a certain amount
(450e500 ml) of deionized water. By rapid stirring, moderate
(95e105 ml) concentrated nitric acid was added into the dissolving
tank. After complete dissolution, insolubles were filtered out and
the remaining clear filtrate was mixed solution of UO2(NO3)2 and
Gd(NO3)3.