Dry recovery of ceramic uranium dioxide waste material

Three dry recovery routes of ceramic uranium dioxide waste material were studied: (a) calcination of waste material to U₃O₈ and blending with the original UO₂ powder; (b) calcination to U₃O₈, then reduction to UO₂ and blending with the original UO₂ powder; (c) grinding the waste material to a fine powder and blending with the original UO₂ powder. The first route resulted in an increased open porosity and decreased closed porosity of the sintered UO₂ pellets. The second recovery route had almost no effect on the quality of the sintered pellets, while the third route caused an increase in open porosity up to about 15-18 wt% of the added scrap material and increased closed porosity for higher concentrations of the added recovery material. Effects of sieving the recovered scrap powders were also investigated. No effects were observed for the first and second recovery routes, while for the third route more pronounced effects were obtained for coarsely ground powders.