Development of Industrial-Scale Fission 99Mo Production Process Using Low Enriched Uranium Target

Molybdenum-99 ( 99 Mo) is the most important isotope because its daughter isotope, technetium-99m ( 99m Tc), has been the most widely used medical radioisotope for more than 50 years, accounting for > 80% of total nuclear diagnostics worldwide. In this review, radiochemical routes for the production of 99 Mo, and the aspects for selecting a suitable process strategy are discussed from the historical viewpoint of 99 Mo technology developments. Most of the industrial-scale 99 Mo processes have been based on the fission of 235 U. Recently, important issues have been raised for the conversion of fission 99 Mo targets from highly enriched uranium to low enriched uranium (LEU). The development of new LEU targets with higher density was requested to compensate for the loss of 99 Mo yield, caused by a significant reduction of 235 U enrichment, from the conversion. As the dramatic increment of intermediate level liquid waste is also expected from the conversion, an effective strategy to reduce the waste generation from the fission 99 Mo production is required. The mitigation of radioxenon emission from medical radioisotope production facilities is discussed in relation with the monitoring of nuclear explosions and comprehensive nuclear test ban. Lastly, the 99 Mo production process paired with the Korea Atomic Energy Research Institute's own LEU target is proposed as one of the most suitable processes for the LEU target.