A study was initiated to determine the highest 235U enrichment that could be processed safely in a facility originally designed for refining natural uranium ores and concentrates. The equipment used in converting uranyl nitrate to uranium trioxide was determined to be the limiting factor. Calculations of neutron multiplication throughout the denitration cycle were made using data from the analysis of process material. It was determined that the maximum 235U enrichment could be safely increased to 2.0% from the previous limit of 1.25% 235U. Processing at the higher enrichment required slight changes in equipment to ensure against moderation of the material.