99mTc is the most widely used radioisotope for imaging in nuclear medicine. It emerges via β-decay from is parent nuclide 99Mo, which for its part is generated to over 95 % from the fission of 235U. This process currently takes place in eight major research reactors worldwide, FRM II being the ninth providing additional 99Mo activity starting in 2021/2022. The exchange of the formerly used HEU irradiation targets in favor of LEU targets results in a decrease in volumetric 99Mo activity by as much as 60% as well as an increase in waste volume of up to 200 % for the currently used extraction routes. To counter these difficulties, FRM II has developed an advanced PVD-process for the fabrication of cylindrical monolithic LEU foil targets with a theoretical uranium loading of up to 16 g/cm3. This process is complemented by a dry-chemical extraction process for 99Mo based on the conversion of U and Mo to their corresponding hexafluorides as well as their subsequent photodissociative separation.
Dr. Christian Franz
Dr. Christian Lang