Study of Factors with Effects on the Grain Size in Gd₂O₃-UO₂ Pellets

The factors with effects on the grain size in Gd₂O₃-UO₂ pellets have been investigated by metalloscope and image analyzer. We have investigated the effects on the grain size in Gd₂O₃-UO₂ pellets due to the sintering atmosphere, blending methods, pellets position in sintering furnace, and additive U₃O₈, ammonium oxalate and oxides （Al, Ti, V） in Gd₂O₃-UO₂ pellets. The results have shown that grain growth and grain size distribution homogeneity of Gd₂O₃-UO₂ pellets were enhanced by mixing methods using ball process, additive of oxides （Al,Ti,V） and sintering of low oxidizing atmospheres. The effect of adding U₃O₈ and ammonium oxalate on the grain growth of pellets is not obvious.