Accession Number : AD0664759

Title :   EFFECTS OF SURFACE IRREGULARITIES ON RADIATION LEVELS,

Corporate Author : PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF NUCLEAR ENGINEERING

Personal Author(s) : Foderaro, A ; Kenney, E. ; Luckow, T. ; Simon, J.

Report Date : DEC 1967

Pagination or Media Count : 121

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)

Descriptors :   (*NUCLEAR RADIATION, DOSE RATE), (*DOSE RATE, SURFACE PROPERTIES), RADIATION DOSAGE, SURFACE ROUGHNESS, EXPOSURE(PHYSIOLOGY), RADIATION MEASURING INSTRUMENTS, SOILS, SPECTROMETERS, PAVEMENTS, SNOW, ASPHALT, CONCRETE, MONTE CARLO METHOD, THICKNESS, DETECTORS, GLASS, ICE, SHIELDING, TEST METHODS.

Subject Categories : Radioactiv, Radioactive Wastes & Fission Prod

Distribution Statement : APPROVED FOR PUBLIC RELEASE