Browsing by Subject "Neutron generator"
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Item 14 MeV neutron generator dose modeling(2013-12) McConnell, Kristen Alycia; Biegalski, Steven R.Modeling and understanding the doses around the neutron generator provides insightful data in regard to radiation safety and protection precautions. Published data can be used to predict doses, but realistic data for the Nuclear Engineering Teaching Laboratory’s Thermo MP 320 Neutron Generator helps health physicists more accurately predict dose rates and protect experimenters against exposure. The goal was to create a model inclusive of the entire setup and room where the neutron generator is housed. Monte Carlo N-Particle (MCNP) Code reigns as the preferred method for modeling radiation transport and was utilized to model the transport of neutrons within the current configuration of the 14 MeV neutron generator facility. This model took into account all shielding materials and their respective dimensions and locations within the concrete room. By utilizing tallies and tally modifiers, the model predicts dose rates that can be used with experimental factors such as irradiation time and flux to predict a dose in millirem. Validation experiments were performed in the current setup using Landauer Luxel®+ with Neutrak dosimeters placed in strategic locations to record the neutron dose vi received as well as a Ludlum Model 42-41 PRESCILA neutron probe to predict dose rates. The dosimeters and PRESCILA measurement locations matched the positions of the point detector tallies in MCNP. After laboratory analysis, a comparison was performed between the model output and the dosimeter and PRESCILA values to successfully validate the accuracy of the model.Item Development of fast pneumatic system for the study of 14 MeV fission product yields(2014-05) Montgomery, Matthew Taylor; Biegalski, Steven R.The use of fission product yield data is pervasive among nuclear calculations, particularly in the realm of nuclear forensics and active interrogation for special nuclear material. The capital source of fission product yield data is the work of T.R. England and B.F. Rider, of Los Alamos National Laboratory, in the early 1990s. Though their work was certainly substantial, a great deal of data was generated computationally, in lieu of done empirically—particularly with low-yield, short-lived progeny. Due to this, relative uncertainties in the measurements can be as high as 64%, and vary wildly from database to database (oft times not even within one standard deviation of one another). The purpose of this work is to build a pneumatic system capable of cyclic irradiation coupled to a D-T neutron source, in order to cumulate proper counting statistics, by which one can backcalculate independent and cumulative fission yields. Beyond the design and control parameters of the pneumatic system, a precise flux characterization of the facility is presented, and finally, proof-of-concept is demonstrated by causing 14 MeV neutron-induced fission and identifying every observed fission product photopeak.