Sao Paulo, Brazil PRESENT STATUS OF THE USE OF LEU IN AQUEOUS REACTORS TO PRODUCE MO-99

Abstract: An operating aqueous homogeneous reactor, the ARGUS at Kurchatov Institute, has been used to produce fission product molybdenum-99 (Mo-99), widely used in nuclear medicine to produce technetium-99m (Tc-99m). The Mo99 has been extracted from the sulfate solution using an organic sorbent after operation at 1 kW/liter. After purification, the material has been assayed and the result is well within required specification of the US Pharmacopaeia. Operation with LEU is planned to determine if any additional purification steps are required. Calculations are presented to show the sources and quantity of alpha activity when LEU is used. 1.0 BACKGROUND Nuclear medicine has relied on Tc-99m and its parent Mo-99 for diagnostics since its development at Brookhaven National Laboratory (USA) in 19641. Over 35,000 procedures per day using Tc-99ni created by Mo-99 are performed throughout the world. The major source of the Mo-99 is from fission of U-235. The uranium is formed into targets which are irradiated by neutrons from research or test reactors. These irradiated targets are dissolved and the fission product, Mo-99, is extracted from the solution