Characteristic Changes of (U, Ce)O2 Pellet Sintered by Addition of MO2 or M3O8 Scrap Powder and Different Sintering Processes

Abstract

MO2 scrap powder was recovered by the mechanical crushing-milling or by the oxidation-reduction of a (U, Ce)O2 pellet, and M3Q5 powder by the oxidation of the pellet. The MQ2 or M3O8 scrap powder was reused up to 30wt% by adding it to UO2+5wt%CeO2 with two different powder treatment routes. The morphology and the addition effects of each scrap powder on sinterability were investigated with the powder routes and the sintering processes. Densification behaviors of the scrap-added powders were studied in an oxidizing atmosphere. A step was observed in each shrinkage curve between 900 and 1060°C as a result of shrinkage measurement up to 1500°C in CO2. Both the sintered density and the pore distribution could be controlled by the powder treatment method and the adding amount of scrap powder. Grain size of the pellet does not depend mainly on the powder process but on the sintering process.