Browsing by Author "B. Wieland, Committee Member"

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    Advanced Thermosyphon Targets for Production of the 18F Radionuclide.
    (2007-03-26) Stokely, Matthew Hughes; M. Shearer, Committee Member; G. Bida, Committee Member; B. Wieland, Committee Member; J. Michael Doster, Committee Chair; M. Bourham, Committee Member
    Single phase and boiling batch water targets are the most common designs for the cyclotron production of 18F via the 18O(p,n)18F reaction. Thermosyphon targets have design and operating characteristics which enables higher power operation than conventional boiling targets of like size. Experiments and calculations were performed in order to characterize the performance of a 1.3 cc tantalum [18F]Target. The test target led to the development of a variety of computational techniques as well as experimental methods that will be used in future target design and optimization. Computational methods include several applications of Monte Carlo Radiation Transport as well as Finite Element Analysis. In addition, experimental thermal hydraulic and radiochemical analyses were performed.
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    High Capacity Heat Exchangers for Recirculating 18F Radionuclide Production Targets
    (2007-03-28) Newnam, Robert Pruett; J.M. Doster, Committee Chair; T. Gerig, Committee Member; M. Haider, Committee Member; B. Wieland, Committee Member; M. Bourham, Committee Member
    North Carolina State University in conjunction with Bruce Technologies Inc. is developing recirculating water targets for the cyclotron production of high yields of 18F fluoride for PET radiopharmaceuticals. Flourine-18 is commonly produced through proton irradiation of 18O enriched water by the 18O(p,n)18F reaction. Heat deposited in the target fluid by the proton beam is proportional to the 18F produced, thus production is often limited by the targets ability to reject heat. For power levels above 3 kW, boiling batch targets with local cooling can become impractical due to excessive 18O water volumes. One potential solution is a recirculating target system where the target water velocity is sufficient to prevent boiling. In this design the heated fluid travels through an external heat exchanger of sufficient capacity to remove the heat, and then through a pump which returns the cooled fluid to the target. A high-flow/low-volume pump and a high-capacity/low-volume heat exchanger are essential to the overall performance of the recirculating target. In this work, two different types of heat exchangers are considered. Laboratory testing was conducted on a small shell and tube heat exchanger that removed nearly 6 kW of heat at flows provided by a miniature regenerative turbine pump. Laboratory testing was also conducted on a small cross flow heat exchanger with measured performance of 7.4 kW and predicted peak performance approaching 10 kW.