Evaluation of heterogeneity degree of U compounds to be used in intercomparison programs in the Brazilian nuclear facilities

The Brazilian nuclear facilities must dispose of measurement systems that allow the determination of their nuclear material inventories. The main goal of this work is the characterization of enriched uranium dioxide (UO₂) pellets to use as secondary standard to evaluate and verify these systems through the participation of the involved laboratories in interlaboratorial comparison programs. The programs are formed by a network of specialized laboratories in determining the material the nuclear fuel cycle. Therefore, before being sent to laboratories, the materials must have their homogeneity certified. The technique used was Davies and Gray/NBL titrimetric method. No statistical significant differences were observed in the results of total U concentration for two different batches. Therefore, the UO₂ pellets are considered homogeneous and can be used in an independent Brazilian measurement systems evaluation program.