Verification and Validation of Radiation Protection Factors from Monte Carlo Simulations
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 of 1.187 + or - 0.003, with statistically significant agreement between neutron MCNP6 models and experiments and a gamma protection factor (GPF) with statistically significant agreement to the measured GPF with a 95% confidence interval. Efforts to validate more complex enclosures using the Fast Burst Reactor (FBR) yielded the first-ever direct measurements of this reactors prompt gamma emission spectrum and revealed irreconcilable differences between the FBR facility-provided source spectrum and spectrometer measurements, resulting in modeled GPFs 27% to 106% higher than experimental GPFs. The use of a tallying annulus reduced the variance in simulations of the FBRs 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 in 36 hours using a laptop computer with an i7-4700MQ processor. The effects of different simulation and calculation methods on RPFs are examined and discussed, along with recommendations and lessons learned for future work.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 16, 2021
- Accession Number
- AD1161486
Entities
People
- William J. Erwin
Organizations
- Air Force Institute of Technology