Source Normalization Constants for Ground Distributed Fallout Fields

Abstract

Five assumptions regarding a first order model developed to calculate dose rate at a detector above a fallout field are analyzed. The omission of scattering is relaxed by the method of successive scatters resulting in a build up factor of 1.1. The use of a single average photon energy to represent a fallout distribution is analyzed using the Oak Ridge National Laboratory Isotope Generator (ORIGEN) Fallout Analysis Tool. An average photon energy of 0.81MeV is calculated and shown to be an accurate approximation of the fallout field energy distribution. A Gaussian distribution is used to calculate the minimal impact of nonuniform activity density on the source normalization constant (SNC). The effects of time on the SNC are also examined by the ORIGEN Fallout Analysis Tool and shown to warrant an additional time correction factor. Finally, previous research accomplished by Herte reveals 2-5% self-shielding from terrain roughness. These findings are incorporated into an updated SNC value that is 25% greater than the value found from the first order model.

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Document Details

Document Type
Technical Report
Publication Date
Sep 01, 2011
Accession Number
ADA549218

Entities

People

  • Justin M. Smith

Organizations

  • Air Force Institute of Technology

Tags

DTIC Thesaurus Topics

  • Air Force
  • Blood Coagulation Factors
  • Department Of Homeland Security
  • Detectors
  • Distribution Functions
  • Dose Rate
  • Fissile Materials
  • Gamma Ray Spectra
  • Gamma Rays
  • Gaussian Distributions
  • Mean Free Path
  • Nuclear Weapons
  • Roughness
  • Scattering
  • Shielding
  • Slant Range
  • X Rays

Fields of Study

  • Physics

Readers

  • Computational Modeling and Simulation
  • Nuclear and Radiation Engineering.