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Medical Isotope Production without Highly Enriched Uranium
of alkaline dissolution, uranium precipitation rates and filtration rates can also be determined.
Many of the important back-end uncertainties can be assessed through tracer testing (“slightly hot” testing) using only very small amounts of radioactive material. These tests could use stable Mo-98 that is spiked with tracer amounts of Mo-99 and radioactive impurities of concern for target processing to determine Mo-99 recovery efficiencies and purity. Because only tracer amounts are used, these tests could probably be carried out in hoods.
Of course, full-scale testing with irradiated LEU targets would be required to demonstrate that the process works as designed. Additionally, some process uncertainties that can only be resolved through full-scale testing with irradiated LEU targets, for example, product purity testing. These tests could probably be carried out in a single hot cell over a period of a few weeks to months.
To the committee’s knowledge, none of the major producers are doing much actual development work17 on LEU targets and process, including the use of cold or slightly hot testing as part of their conversion strategies. The committee views this as a missed opportunity.
Several important technical considerations for converting Mo-99 production from HEU targets to LEU targets were described and discussed in this chapter. Based on this information, the committee finds that:
There are three basic approaches for converting HEU targets to LEU: Direct replacement of HEU in the target with LEU; increasing the mass in U-235 in the target by increasing target size; or increasing the mass of U-235 in the target by changing target composition. Each approach has advantages and disadvantages.
There are no technical barriers to conversion of Mo-99 production from HEU targets to LEU targets. Production using LEU targets is technically feasible and in fact is being carried out by CNEA in Argentina and shortly will be applied by the Australian National Nuclear Science and Technology Organisation (ANSTO) using CNEA technology (see Chapter 3). The committee sees no technical barriers to scaling up to large-scale
HEU-based producers did not provide details of any development work aimed at conversion, either in presentations to the committee or in discussions during site visits. On this basis the committee assumes that development work such as is described above has not been done. The committee is aware of a conversion feasibility study that was carried out by Atomic Energy of Canada Limited (AECL), but that organization was unwilling to share the results of that study with the committee.