Flowsheet Evaluation for the Processing of U-Mo Materials in H-Canyon

Abstract

H-Canyon Engineering (HCE) is evaluating the feasibility of processing material containing 90% uranium (20% 235 U enrichment) alloyed with 10% molybdenum (Mo). The objective is to dissolve the material in nitric acid (HNO 3 ) in the H-Canyon dissolvers to a U concentration of 17-22 g/L (3-4 g/L 235 U) without the formation of precipitates. Following dissolution, the dissolved material will be processed through 1 st and 2 nd Cycle solvent extraction and the U sent to the U blend down program. The flowsheet must also consider any aqueous waste processing and solvent recycle issues.HCE requested that the Savannah River National Lab (SRNL) define a flowsheet for safely and efficiently processing the U-10Mo material. The flowsheet definition will occur in two phases. The first phase involves the evaluation of all available data related to the dissolution and solvent extraction of U-Mo materials to determine if a viable flowsheet can be developed, and to assess if there are additional data that must be obtained.Adequate data are available to conclude with confidence that a flowsheet is viable with sufficient operating margins. Data on the flowsheet development and processing of U-Mo fuels at Savannah River during the 1970's and 1980's provide the best information. Based on the data, the U-10Mo material can be dissolved in boiling 4.5-5.0 M HNO 3 to a U concentration of 17-22 g/L and a corresponding Mo concentration of 1.7-2.2 g/L. Any nickel (Ni) cladding associated with the material will dissolve readily. After dissolution is complete, traditional solvent extraction flowsheets can be used to recover and purify the U. Evaporation of the resulting 1AW waste stream may be limited by Mo solubility. Although the flowsheet is fairly well-characterized, it should be noted that the material to be processed during this campaign is different than those previously processed in that it does not have aluminum cladding. As a result, some additional work is recommended to verify important flowsheet parameters for the specific material to be processed.