Semester of Graduation

Fall 2019


Master of Science (MS)


Health Physics

Document Type



Iodine 131 is a major fission product released during a nuclear incident. This isotope provides a serious health hazard for humans and the environment, therefore nuclear power plants must monitor releases using air sampling. The air sampling is accomplished using air filter cartridges using silver zeolite as a filter media. During an emergency situation, silver zeolite is useful for its affinity to I-131 without adsorbing other radioactive gases. After leaving the plume, these cartridges are counted in a low background area. This measurement does not take into account the distribution of radioiodine in the cartridge. This study explores two methods of quantifying and visualizing the radioiodine within a silver zeolite cartridge, conjugate counting and single photon emission computed tomography (SPECT) imaging. Two silver zeolite cartridges were used as phantoms, one with I-131 and one with Ba-133, in the conjugate counting setup. The barium cartridge was used for efficiency and attenuation measurements, while the iodine cartridge was used for activity measurements. The iodine cartridge was also imaged using a SPECT system to determine the visibility of a pattern of I-131 placed in the cartridge. We found that the conjugate counting method provides an average activity measurement 8.8% different than the actual activity, compared to 28.4% different and 25.1% different for the individual faces. We were able to identify the pattern placed into the silver zeolite cartridge using the SPECT system and could determine that imaging a real-life cartridge with a lower activity could be done within 25 hours with a reasonable spatial resolution. We determined that the conjugate counting method is a reasonable addition to normal air monitoring for more accurate activity measurements. We also determined that SPECT imaging can be used to image a lower activity cartridge in a real-life scenario within a reasonable amount of time.

Committee Chair

Matthews, Kenneth L II