Date of Award

9-2021

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Department of Engineering Physics

First Advisor

John W. McClory, PhD

Abstract

This dissertation describes the verification and validation of methods for producing radiation protection factors (RPFs) using experiments and Monte Carlo N-Particle 6 (MCNP6) simulations. RPF validation of a steel enclosure using a plutonium-beryllium source produced a validated RPF with statistically significant agreement between neutron MCNP6 models and experiments and a gamma protection factor (GPF) with statistically significant agreement to the measured GPF. Efforts to validate more complex enclosures using the Fast Burst Reactor (FBR) yielded the first-ever direct measurements of this reactor’s prompt gamma emission spectrum and revealed irreconcilable differences between the FBR facility-provided source spectrum and spectrometer measurements, resulting in modeled GPFs higher than experimental GPFs. The use of a tallying annulus reduced the variance in simulations of the FBR’s projected radiation field by three orders of magnitude. Annulus-based tallying enabled the demonstration of a nuclear weapon-like irradiation of a target at 1400 meters, yielding statistically significant gamma and neutron flux spectra. The effects of different simulation and calculation methods on RPFs are examined and discussed, along with recommendations and lessons learned for future work.

AFIT Designator

AFIT-ENP-DS-21-S-027

DTIC Accession Number

AD1161486

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