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Show LEXAN LUCIDITY DUE TO NEUTRON FLUENCE In Fission Track Analysis, samples of low-level concentrations of 239Pu are deposited onto solid-state nuclear track detectors and irradiated in a nuclear reactor to produce fission tracks. The tracks are then counted to determine the radionuclide concentration in the samples. During the irradiation procedure, energetic neutrons also collide with the detectors producing further damage that can impede the final detection process of fission tracks, especially when visually inspecting detectors such as Lexan polycarbonate beneath a microscope. This experiment compared the reduction in slide lucidity (transparency) due to fast and thermal neutrons with increasing neutron fluence conditions, where fluence denotes the number of neutrons impacted upon the Lexan surface area. Results show that in a thermal neutron irradiator with cadmium ratio of 7.623, the lucidity of a Lexan slide does not significantly decrease as the fluence is increased. However, as the fluence is increased in a fast neutron irradiator with a cadmium ratio of 3.560, the lucidity of the slide decreases significantly. A cadmium ratio represents the ratio of the total neutron population to the fast neutron population; therefore, a higher cadmium ratio signifies a higher population of thermal neutrons. It was determined that slide preparation, reactor temperature, and etching procedures were not significant in reducing the overall lucidity of the Lexan. Therefore, Lexan should be irradiated with thermal neutrons in order to minimize damage to the detector that would decrease slide transparency and incur track detection errors during visual inspection of the slides. John Darrell Bess Senior Chemical Engineering jdbess_phoenix@hotmail.com Faculty Sponsor: Melinda Krahenbuhl Center for Excellence in Nuclear Technology mpk@nuclear.utah.edu 13 |
