Modification of targets and processes for conversion of Mo-99 production from high- to low-enriched uranium

As part of the U.S. nonproliferation effort, Ne are investigating the conve rsion of the production of fission-product Mo-99 from use of high-enriched uranium (HEU) to low-enriched uranium (LEU). Successful conversion from HEU to LEU (<20% U-235) requires an irradiation target that contains 5 times m ore uranium but minimizes changes to target geometry and processing. The LE U target being developed uses thin foils of uranium metal that can be remov ed from the target hardware for dissolution and processing. This paper desc ribes our recent successes in target fabrication, irradiation, and processi ng. Target fabrication has been improved by (1) heat-treating the uranium f oil to produce a random, small-grain structure and (2) electrodepositing zi nc and nickel fission-fragment barriers onto the foil. These fission-fragme nt barriers have been found to be stable during transport of the targets fo llowing irradiation. Recent irradiation tests have shown that the concept i s sound. Progress was also made in broadening international cooperation in our development activities.