Processing of Low-Burnup LEU (Low Enriched Uranium) Silicide Targets.

摘要

Currently much of the world's supply of (sup 99m)Tc for medical purposes is produced from (sup 99)Mo derived from the fissioning of high enriched uranium (HEU). Substitution of low enriched uranium (LEU) silicide fuel for the HEU alloy and aluminide fuels used in current target designs will allow equivalent (sup 99)Mo yields with no change in target geometries. In these studies, targets were irradiated to low burnup (10(sup -5)%) to produce fission products and (sup 239)Np at concentrations conveniently measured by gamma spectroscopy. Processing was done by dissolution of LEU targets in acid or base followed by alumina column recovery (sup 99)Mo. Acid dissolution is more rapid, but precipitation of silica results in loss of (sup 99)Mo. Dissolution of U3 Si2 --Al targets in base requires more processing steps than the current process for UAlx--Al fuel. A two-step process of first dissolving the 6061Al cladding and fuel meat aluminum, and then dissolving the U3 Si2 fuel particles, has the advantage of eliminating the aluminum from further processing. Loss of (sup 99)Mo during the aluminum dissolution is attributed to recoil of (sup 99)Mo out of the silicide particles during irradiation. A larger particle size would decrease this (sup 99)Mo loss. 6 refs., 4 figs., 2 tabs. (ERA citation 14:013234)