ДЄlthough molybdenum can be recovered from both uranyl nitrate and uranyl sulfate solutions, the task is easier from nitrate media. Ferrous and ferric sulfate, cupric sulfate, potassium iodide, 304 stainless steel turnings, and Zr metal have been tested as potential catalysts for peroxide destruction during irradiation of uranyl sulfate solutions. Uranyl peroxide precipitated during irradiation of uranyl sulfate solutions that did not contain catalysts. The pH of a uranyl sulfate solution decreased postirradiation due to water loss from radiolysis. As a result, nitric acid will need to be added periodically to the uranyl nitrate MIPS fuel solution during operation to prevent large pH increases that may lead to the precipitation of some fission products and eventually uranium. Uranium and fission product precipitation becomes a concern when the pH rises above 3. The effect of a high radiation field caused significant pH changes in a uranyl nitrate solution, which resulted from the radiolysis of nitrate to form a variety of reduced nitrogen species from nitrite to gases and to ammonia. Uranyl nitrate and uranyl sulfate solutions have been irradiated at the Argonne 3вЂ‰MeV Van de Graaff accelerator to study the effects of a high radiation field on solution chemistry, specifically related to pH changes, peroxide formation, and molybdenum and iodine redox chemistry. The differences in procedures will be discussed in more detail below. Solution preparation is much easier for MIPS compared to SHINE. For these systems, Argonne has developed a Mo-recovery process for either the irradiated uranyl sulfate or uranyl nitrate solution using a titania sorbent.

SHINE Medical Technologies is developing Subcritical Hybrid Intense Neutron Emitter (SHINE), which is an accelerator-driven process that will use an LEU uranyl sulfate target solution for Mo-99 production.

Their system is referred to as MIPS (Medical Isotope Production System). Babcock and Wilcox Technical Services Group (BWTSG) is developing an aqueous homogeneous reactor (AHR) for Mo-99 production, which will utilize an LEU fuel (19.75% U-235) as uranyl nitrate. IntroductionДЄrgonne is assisting two potential domestic suppliers of Molybdenum-99, and both plan to use a fissioning LEU solution as either uranyl nitrate or uranyl sulfate to produce Mo-99. A titania sorbent can be used to recover Mo-99 from a highly concentrated uranyl nitrate or uranyl sulfate solution however, different approaches must be taken to prevent precipitation during Mo-99 production. Uranyl sulfate solutions are more difficult to prepare, and enough peroxide is generated during irradiation to cause precipitation of uranyl peroxide, but this can be prevented by adding a catalyst to the solution. Uranyl nitrate solutions are easier to prepare and do not generate detectable amounts of peroxide upon irradiation, but a high radiation field can lead to a large increase in pH, which can lead to the precipitation of fission products and uranyl hydroxides. Argonne National Laboratory is assisting two potential domestic suppliers of Mo-99 by examining the effects of a uranyl nitrate versus a uranyl sulfate target solution configuration on Mo-99 production. There are currently no US producers of Mo-99, and NRU is scheduled for shutdown in 2016, which means that another Mo-99 shortage is imminent unless a potential domestic Mo-99 producer fills the void. The medical community has been plagued by Mo-99 shortages due to aging reactors, such as the NRU (National Research Universal) reactor in Canada.

Molybdenum-99 is the parent of Technetium-99m, which is used in nearly 80% of all nuclear medicine procedures.

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