| Technetium-99m is currently the most widely used nuclear isotope in the medical field. Globally, more than 20 million samples are used annually to diagnose many different forms of cancer. Despite this, there are only four main nuclear reactors worldwide that produce molybdenum-99, the parent isotope of technetium-99m. In an attempt to address the growing demand, as well as to motivate the current reactors to stop using high-enriched uranium, the University of Missouri Research Reactor (MURR) has begun to produce molybdenum-99 using low-enriched uranium.;The fission of uranium-235, for which one of the products is molybdenum-99, generates approximately 2 kW of heat per 4-gram target. Continually removing this heat from the fission reaction is the limiting factor in the high-volume production process. The objective of this report is to find a reactor wedge setup with maximum rate of heat removal, thereby maximizing the amount of molybdenum-99 that can be created in the reactor.;To determine the best heat transfer, a quasi 1-D analytic model, calibrated numerically, is created to hydraulically and thermally model the coolant flow through the current reactor setup. Using flow network modeling (FNM), this analytic model is expanded to analyze other potential geometries that could maximize heat transfer. The findings show that for a single channel under the existing reactor configuration, a maximum of 19.18 kW can be dispersed. By opening the drain and slightly shrinking the channel diameter, this can be improved to 22.77 kW. When the system is expanded to 10 parallel channels, the rate of heat transfer for the current drain and target geometries tops out at 47 kW. With changes to these parameters, this value can be raised to over 250 kW, though the neutronics of the MURR reactor may limit this. The final setup that is examined uses 8 plate targets in each of 3 parallel channels. The optimum rate of heat transfer for this configuration is 190 kW. |
