Aqueous Dissolution Characteristics and Off-Gas of U-10Mo Scrap Material for Uranium Recovery

Low-enriched uranium–10% molybdenum (U-10Mo) fuel is fabricated from a dense U alloy that can potentially replace highly enriched uranium–aluminum alloy fuels or be used in advanced reactors. The fabrication of U-10Mo fuel results in scrap material in the forms of U-10Mo and U-10Mo-Zr foils, rejected Al-clad U-10Mo-Zr fuel plates, and U-10Mo skull oxide from casting operations.The objective of this work was to find a streamlined process to efficiently dissolve the U-10Mo scrap material with target U concentrations of 20 g/L and 50 g/L. While scoping studies have demonstrated that U can be recovered from U-10Mo scrap material in an aqueous dissolution process, there are several complications to consider. For instance, the use of fluoride is recommended to prevent the exothermic dissolution of an explosive UZr2 intermetallic compound. Sufficient nitric acid is needed to prevent precipitation of uranyl molybdate and other chemical species.Most importantly, this research used Raman spectroscopy to track the off-gas during the dissolution of the U-10Mo scrap material. Significant quantities of H2 were generated during the dissolution of the Al cladding and some from the dissolution of the U-10Mo-Zr foil and decladded U-10Mo-Zr mini-plates. The H2 concentrations could be managed by supplying an air purge to the dissolver to dilute the H2 concentration, the volume of air would then be dependent on how much material is dissolved at a time.