Designs of Column Separation Processes for Recovery of Molybdenum from Dissolved High-Density LEU Target - Further Studies
The Global Threat Reduction Initiative (GTRI) Conversion Program develops technology necessary to convert civilian facilities that use high enriched uranium (HEU) to low enriched uranium (LEU) fuels and targets. The conversion of conventional HEU dispersion targets to LEU for the production of 99 Mo production requires approximately five times the uranium in a target to maintain the 99 Mo yield per target. Under GTRI, Argonne National Laboratory (Argonne) is developing two frontend options for the current processes to allow the use of LEU-foil targets. In both processes, the aim is to produce a product after the frontend that will be compatible with current purification operations and that will, with the same number of targets irradiated, provide the same or a higher yield of 99 Mo at the end of processing. The goal of the frontend process is to deliver a product solution that is of the same or higher Mo purity than the current solution and is of equal or better compatibility with current purification process. In the first frontend option, the LEU foil (contained in a thin [10–15 µm] Ni fission-recoil barrier) is removed from the annular target and dissolved in nitric acid. In the dissolution, the uranium, nickel, and all fission and activation products are dissolved; the solution will be ~7 mM Mo and ~450 g-U/L, and the nitricacid concentration after dissolution will be ~1 M. The resultant solution will then be run through a column to recover Mo from other target components; the Mo will be stripped from the column with a sodium hydroxide solution that will be compatible with the current purification processes used for dispersion targets. The volume of dissolved-foil solution is assumed to be 500 mL, and the pressure drop, ΔP, constraint of 0.8 atm is based on the use of vacuum/gravity fluid transfer system. Therefore pressure loss is limited to <1 atm; hence a value of 0.8 was chosen.