EFFECTS OF SURFACE IRREGULARITIES ON RADIATION LEVELS,
Abstract
Scintillation spectrometer pulse height spectrums for surface roughness tests sponsored by the US Army Nuclear Defense Laboratory were unfolded by the method of N. E. Scofield. After adjusting the data to compensate for some irregularities, exposures as functions of height were computed for each of eight test surfaces. A Monte Carlo model was developed which used an equivalent ground overlayer thickness to simulate surface roughness effects. Monte Carlo results predicted that maximum dose occurs at a lower height than that of the experimental data. A modification of this Monte Carlo program, written to determine what angular dependence, if any, dose had away from a point source at or near the ground surface, showed dose to be roughly a function of the angle which the source-detector line made with the horizontal. Correction factors as functions of this angle were computed. Average doses at three feet height for all eight test surfaces were extrapolated out to infinite field doses using these angle correction factors and inverse square correction factors. The ratios of these infinite field doses to theoretical uncollided doses from a smooth infinite plane source in an infinite air medium were computed. Reductions of 20 to 25 percent were found for 'Bare, Sandy Soil' and 'Turf' surfaces. 'Macadam' and 'Snow' surfaces showed smaller reductions and 'Asphalt', 'Concrete', 'Ice', and 'Glass' show experimentally extrapolated doses to be virtually the same as theoretical uncollided doses. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1967
- Accession Number
- AD0664759
Entities
People
- A. Foderaro
- E. Kenney
- James B. Simon
- T. Luckow
Organizations
- Pennsylvania State University