Engineering Commons^™

Modeling And Simulation Of Stochastic Neutron And Cumulative Deposited Fission Energy Distributions, Patrick O'Rourke

Nuclear Engineering ETDs

Methods of stochastic neutron transport are investigated and applied to novel formulations for the neutron number distribution and the cumulative fission energy deposition distribution. We utilize two Monte Carlo algorithms: the event-based Monte Carlo (EBMC) method and the Stochastic Simulation Algorithm (SSA) to benchmark and analyze systems. We show that the SSA outperforms the EBMC for the parameter space we are interested in. We then utilize the SSA to analyze systems composed of multiple spherical regions with fast and thermal neutrons with time-dependent reactivity insertions and determine whether group-dependent number distributions approach a gamma distribution. We develop two methods for …

Calculation And Tabulation Of Efficiencies For Tungsten Foil Positron Moderators, R. Alsulami, M. Albarqi, S. Jaradat, Shoaib Usman, Joseph T. Graham

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

Monte Carlo radiation transport simulations were used to calculate the positron stopping profiles in tungsten positron moderator foils. Stopping profiles were numerically integrated with efficiency kernels derived from Green's function solutions of the 3D diffusion equation to determine the moderation efficiency in both the backscattering and transmission geometries. Stopping profiles and efficiencies were calculated for positron energies from 10 keV to 10 MeV and incident angles from 0° to 75°. The resulting efficiencies agreed with other calculated and measured values in the literature, especially when similar values of the positron diffusion length and surface emission branching ratio were used. Large …

Hybrid K-Edge Densitometry As A Method For Materials Accountancy Measurements In Pyrochemical Reprocessing, Matthew Tyler Cook

Doctoral Dissertations

Pyrochemical reprocessing is a proven method to recover useful fissile material from spent nuclear fuel. The process requires high temperatures and an inert atmosphere thus complicating the prospect of making materials accountancy measurements. Development of a measurement method for materials accountancy measurements has become necessary since pyroprocessing is receiving more attention as a possible compliment to aqueous reprocessing methods. If pyroprocessing is to be adapted from the engineering scale to a commercially viable reprocessing method a comprehensive safeguards measurement method and strategy must be developed.

Hybrid k-edge densitometry (HKED) has been applied to aqueous reprocessing measurements in commercial facilities. This …