DOE OSTI2014
An irradiation experiment was designed for the production of 100 mCi of medical isotope Mo-99 from a Low Enriched Uranium (LEU) solution. 300 mL of 150 gU/L LEU sulfate solution (pH1) was prepared and irradiated at the LANSCE Blue Room facility. The apparatus designed for the irradiation included a gas handling system, in which safe operation could be controlled by monitoring change in gas pressure. The gas handling system also contained a hydrogen oxygen recombiner, to recombine the gases generated through radiolysis of water, and an iodine trap, primarily for I-131. Pressure transients were observed during irradiation, which could be controlled by increasing the flow rate of the circulating pump. After irradiation the LEU solution was transferred to a hot cell facility for subsequent Mo-99 recovery using a titania column separation process, with samples also subsequently shipped to a radiochemical laboratory for further analysis. Gamma spectroscopy analysis revealed that ca. 70 mCi of Mo-99 was present at end of beam, in good agreement with the predicted value when actual beam history was included into the calculation. There was 80-85 % recovery of Mo-99 through a titania column separation, excluding losses through radioactive decay. The % Mo-99 recovery was lower than observed previously for the 1 mCi Mo-99 production (Target 4) experiments undertaken at LANL using the same separation apparatus, with on this occasion evidence of lower oxidation state molybdenum remaining irreversibly bound to the titania column. Subsequent postmortem analysis of the Blue room apparatus revealed that there had been no leaks in the gas handling system, the hydrogen and oxygen recombination appeared to work efficiently, and recovery of irradiated uranium trapped in the system allowed for >99% uranium mass balance.
07 ISOTOPE AND RADIATION SOURCES↗