PNNL

Abstract

Production of the important 99mTc medical isotope parent, Molybdenum-99 (99Mo), via the fissioning of high- and low-enriched uranium (HEU / LEU) targets followed by target dissolution in acid and solution-phase purification of 99Mo is time-consuming, generates quantities of corrosive radioactive waste, and can result in the release of an array of radionuclides to the atmosphere. An alternative 99Mo purification method has been devised that has the potential to alleviate many of these issues. Herein, we demonstrate the feasibility of Mo / Tc gas-phase separation from UO2 using the thermo-gravimetric technique. Conditions are identified that make possible the volatilization of Mo / Tc fluorides using the fluorinating gas NF3 within a furnace; under these conditions, UO2 to UO2F2 conversion is observed, without formation of gaseous UF6. Next, a simple proof-of-concept experiment was performed to demonstrate the gas-phase separation of [99Mo]Mo as [99Mo]MoO2 that was homogeneously mixed with UO2. The results indicate that volatilized [99Mo]Mo can be captured downstream of the reacted mixture on a column bed (trap) of alumina; the majority of the captured [99Mo]Mo can be subsequently eluted from the alumina trap with a few milliliters of water. While the initial U:Mo mole ratio in the solid sample mixture was 7.5:1, the U:Mo ratio in the recovered [99Mo]Mo fraction was <1. this="" represented="" a="">